Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/23/14


AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
357 AM PDT THU AUG 21 2014 .SYNOPSIS... AN UPPER LEVEL LOW PRESSURE SYSTEM WILL SLOWLY MOVE EAST OVER EXTREME SOUTHERN CALIFORNIA THURSDAY. THERE IS A VERY SMALL CHANCE OF AN ISOLATED SHOWER OR THUNDERSTORM TONIGHT AND EARLY THURSDAY OVER MOST AREAS...THEN THE CHANCE OF THUNDERSTORMS WILL BE PRIMARILY OVER THE MOUNTAINS AND DESERTS BY THURSDAY AFTERNOON. TEMPERATURES WILL CONTINUE TO BE BELOW NORMAL THURSDAY. AFTER THE LOW EXITS TO THE EAST THURSDAY NIGHT...THERE WILL BE DRY AND WARMER WEATHER FRIDAY FOLLOWED BY SLIGHT COOLING OVER THE WEEKEND. HIGH PRESSURE ALOFT WILL BUILD NEXT WEEK AND BRING A WARMING TREND. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... THE CLOSED UPPER LOW IS LOCATED JUST WEST OF SAN DIEGO EARLY THIS MORNING AND CONTINUES TO WOBBLE SOUTH BUT IS ALSO BEGINNING TO MOVE TO THE EAST ATTM. ALL OF THE SHORT RANGE MODELS SHIFT THE CLOSED LOW TO THE EAST LATER TODAY AS IT GETS PICKED UP BY THE WESTERLIES...ACCELERATING IT EAST TO CENTRAL ARIZONA BY THIS TIME FRIDAY. FOR TODAY THE UPPER LOW SHOULDN`T HAVE MUCH OF AN IMPACT ON COASTAL SOCAL AT THIS POINT AS WE ARE QUICKLY GOING TO BE ON THE BACKSIDE OF THE LOW. HOWEVER THE UPPER CIRCULATION WILL BE INTERACTING WITH THE DIURNAL HEATING OF OUR MOUNTAIN AND DESERT REGIONS AND WILL HELP TO KICK OFF ANOTHER ROUND OF CONVECTION IN THOSE AREAS...PROBABLY AS QUICKLY AS MIDDAY OR EARLY AFTERNOON. MODEL SURFACE CAPE IS FORECAST TO REACH 1000+ J/KG ACCORDING TO THE LATEST 3KM HRRR AND THE HIGH RES NAM AS WELL. MOISTURE PROGS ARE SHOWING SOME MOISTURE ADVECTION TO THE MOUNTAIN AND DESERT AREAS ALTHOUGH NOT SIGNIFICANTLY ABOVE NORMAL VALUES WITH MODEL SOUNDINGS SHOWING PWAT VALUES INCREASING FROM ABOUT 3/4 OF AN INCH TO A LITTLE OVER 1 INCH IN THE SAN DIEGO COUNTY MOUNTAINS THIS AFTERNOON. WITH THIS IN MIND WE BELIEVE THERE WILL BE A MODERATE FLASH FLOOD POTENTIAL COINCIDENT WITH LIKELY POPS IN THE MOUNTAIN AREAS (EXCEPT ORANGE COUNTY MOUNTAINS). FOR TONIGHT THE CONVECTION SHOULD QUICKLY DIMINISH WITH THE LOSS OF HEATING. LIGHT ONSHORE FLOW WILL ALLOW THE MARINE LAYER TO DEEPEN ALONG THE COAST BUT INTRUSION SHOULD BE LIMITED TO THE NEAR COASTAL AREAS TONIGHT AND AT LEAST A PORTION OF THE COASTAL VALLEYS. DIURNAL MARINE INTRUSIONS SHOULD CONTINUE THROUGH THE WEEKEND BUT NOT PARTICULARLY DEEP. LOW CONFIDENCE IN THE SYNOPTIC PATTERN THROUGH MID NEXT WEEK AS SOLUTIONS DIVERGE ON WHETHER A TROUGH WILL DROP OUT OF THE PACNW AND AFFECT SOCAL. ALSO MOISTURE FROM TWO TROPICAL SYSTEMS...KARINA AND LOWELL...WILL HAVE THE POTENTIAL TO ADVECT INTO OUR REGION FOR THE NEXT SEVERAL DAYS ALTHOUGH I`VE NOT SCENE A SOLUTION THAT ACTUALLY BRINGS MUCH MOISTURE THAT FAR NORTH AT THIS TIME. SOMETHING TO KEEP AN EYE ON ANYWAY. && .AVIATION... 211000Z...PATCHY STRATUS...WITH BASES 1600-2100 FT MSL AND TOPS NEAR 2400 FT MSL...WILL CONTINUE TO DEVELOP OVER THE SAN DIEGO COUNTY VALLEYS AND COAST...AND OVER PORTIONS OF ORANGE COUNTY BY SUNRISE THIS MORNING. VISIBILITY WILL LOWER TO 1-3 SM DUE TO MIST AND FOG WHERE STRATUS NEARS HIGHER TERRAIN. LOW CLOUDS WILL CLEAR TOWARDS THE COAST LATE THIS MORNING...THEN REDEVELOP ALONG THE COAST LATE THIS EVENING. ISOLATED SHOWERS AND THUNDERSTORMS...WITH BASES AROUND 8000 FT MSL AND TOPS TO 35000 FT MSL...WILL BE POSSIBLE ACROSS THE REGION THIS MORNING...THEN MAINLY ACROSS THE MOUNTAINS AND DESERTS THIS AFTERNOON. GUSTY WINDS...STRONG UP/DOWNDRAFTS...SMALL HAIL AND LIGHTNING WILL BE POSSIBLE NEAR STORMS. FORECASTER CONFIDENCE IS MEDIUM. && .MARINE... 200 AM...NO MARINE WEATHER HAZARDS ARE EXPECTED THROUGH MONDAY. && .BEACHES... .BEACHES... A 4 TO 5 FOOT...12 SECOND SOUTHERLY SWELL WILL CREATE ELEVATED SURF AND STRONG RIP CURRENTS ALONG THE SAN DIEGO AND ORANGE COUNTY COAST THROUGH THIS WEEKEND. SURF OF 3 TO 5 FEET IS EXPECTED...WITH SETS TO 7 FEET POSSIBLE ALONG SOUTHERLY FACING BEACHES. ELEVATED SURF AND STRONG RIP CURRENTS WILL CREATE DANGEROUS SWIMMING CONDITIONS. A BEACH HAZARD STATEMENT FOR ELEVATED SURF AND STRONG RIP CURRENTS IS IN EFFECT FROM THIS MORNING THROUGH SUNDAY AFTERNOON. && .SKYWARN... SKYWARN ACTIVATION MAY BE REQUESTED LATER TODAY FOR THUNDERSTORMS IN THE MOUNTAINS AND DESERTS. WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...BEACH HAZARDS STATEMENT FROM 9 AM PDT THIS MORNING THROUGH SUNDAY AFTERNOON FOR THE ORANGE COUNTY COASTAL AREAS...SAN DIEGO COUNTY COASTAL AREAS. PZ...NONE. && $$ PUBLIC...BROTHERTON AVIATION/MARINE...JJT
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1104 PM MDT WED AUG 20 2014 .UPDATE... ISSUED AT 636 PM MDT WED AUG 20 2014 UPDATED FORECAST TO ADJUST FOR NR TERM TRENDS. LOOKS LIKE A FEW ISOLD SHOWERS/TS COULD HANG ON OVER THE MTS AND ERN PLAINS THIS EVE...BUT TREND IS DOWNWARD AND COVERAGE WILL BE MINIMAL SO HAVE DROPPED MOST OF THE POPS BELOW 10 PERCENT FOR TONIGHT. ROSE && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 238 PM MDT WED AUG 20 2014 UPR LEVEL LOW IS SITTING ALONG THE SRN CA COAST TODAY AND IS EXPECTED TO MOVE LITTLE IN THE NEXT 24 HOURS. WV SATELLITE IMAGES SHOWING DRIER AIR HAS WORKED IT WAY INTO WRN CO TODAY. HRRR AND RAP SHOWING MAINLY ISOLD PCPN COVERAGE THIS EVENING OVER WESTERN PORTIONS OF THE FORECAST AREA...WITH ISOLATED TO SCT COVERAGE OVR THE ERN MTS AND SERN PLAINS. A WEAK BOUNDARY IS FORECAST TO MOVE INTO THE PALMER DVD AREA EARLY THIS EVENING AND THEN WORK ITS WAY SOUTH. THIS BOUNDARY MAY HELP KICK OFF ADDITIONAL CONVECTION. THERE COULD BE A FEW LINGERING SHOWERS OR TSTMS OVR THE SERN PLAINS...BUT THINK THAT MOST OF THE PCPN SHOULD END BY 06Z. ON THU...IT DOES NOT LOOK ALL THAT MOIST OVR THE FORECAST AREA. PRECIPITABLE WATER VALUES OVR WRN AREAS ARE FORECAST TO BE SIMILAR TO TODAY...WITH DRIER CONDITIONS OVR ERN AREAS. AS A RESULT THE FORECAST MODELS SHOW MAINLY ISOLD TO SCT POPS OVR THE MTNS IN THE AFTERNOON HOURS...WITH POSSIBLY A FEW STORMS OVR THE LOWER ELEVATIONS. HIGH TEMPS FOR THU SHOULD BE AROUND AVERAGE IN THE HIGH VALLEYS...WITH SLIGHTLY ABOVE NORMAL READINGS OVR THE SERN PLAINS. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 238 PM MDT WED AUG 20 2014 NOT MUCH CHANGE TO THE FORECAST THINKING WITH THE GFS COMING INTO LINE WITH THE ECMWF AND NAM SOLUTIONS. ENSEMBLES ARE STILL DISPLAYING QUITE A BIT OF SPREAD BY EARLY NEXT WEEK...BUT CONFIDENCE IS A HIGHER THAN IT WAS YESTERDAY IN A FORECAST SOLUTION. AN UPPER LEVEL DISTURBANCE OVER SOUTHERN CALIFORNIA IS FORECAST TO EJECT NORTHEAST ACROSS COLORADO ON FRIDAY. EXPECT A FEW SHOWERS AND THUNDERSTORMS TO BE ONGOING THURSDAY EVENING AND DISSIPATING THROUGH MIDNIGHT OVER THE MOUNTAINS...WITH PERHAPS A FEW LINGERING SHOWERS OVER THE PALMER DIVIDE INTO NORTHEAST COLORADO INTO EARLY FRIDAY MORNING. FRIDAY HAS THE POTENTIAL TO BE INTERESTING. THE UPPER DISTURBANCE OVER ARIZONA WILL EJECT ACROSS COLORADO THROUGH FRIDAY EVENING. MODELS QUICK TO ADVECT MOISTURE NORTH ACROSS COLORADO...AND SHEAR LOOKS TO INCREASE TO AROUND 30 KTS OR SO BY THE AFTERNOON WITH MODEST INSTABILITY. EXPECT SHOWER AND THUNDERSTORM DEVELOPMENT BY MID MORNING FRIDAY ALONG THE CONTINENTAL DIVIDE...AND SPREADING EAST INTO THE I-25 CORRIDOR BY EARLY IN THE AFTERNOON. MODEL QPF FIELDS ARE INDICATING THAT HEAVY RAINFALL WILL BE POSSIBLE...ESPECIALLY OVER THE MOUNTAINS AND LOCATIONS OVER THE PALMER DIVIDE. FLASH FLOODING WILL BE POSSIBLE ON AREA BURN SCARS AND FLOOD PRONE AREAS FRIDAY AFTERNOON AND EVENING. SOME STORMS ACROSS THE PLAINS COULD BECOME STRONG...WITH SMALL HAIL AND GUSTY OUTFLOW WINDS ALSO POSSIBLE. MODELS IN GOOD AGREEMENT WITH THUNDERSTORMS SHIFTING EAST ACROSS THE PLAINS FRIDAY NIGHT WITH ALL ACTIVITY EXITING INTO KANSAS BY SATURDAY MORNING. SATURDAY WILL LIKELY BE A PRETTY QUIET DAY ACROSS SOUTHERN COLORADO GIVEN SUBSIDENCE BEHIND THE DEPARTING UPPER SYSTEM. A COUPLE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE OVER THE MOUNTAINS...BUT COVERAGE LOOKS TO BE MINIMAL. A BROAD TROUGH WILL PERSIST OVER THE WESTERN CONUS THROUGH THE MIDDLE OF NEXT WEEK WITH A COUPLE OF MORE DISTURBANCES MOVING ACROSS SOUTHERN COLORADO. THE NEXT ONE LOOKS TO MOVE ACROSS THE REGION ON SUNDAY. THIS WILL BRING ANOTHER UPTICK IN SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE STATE...WITH ACTIVITY STARTING OVER THE MOUNTAINS LATE SUNDAY MORNING AND SPREADING EAST THROUGH THE AFTERNOON AND EVENING. IN ADDITION...A COLD FRONT WILL MOVE SOUTH ACROSS THE PLAINS DURING THE AFTERNOON...TURNING LOW LEVEL FLOW UPSLOPE...WHICH WILL LIKELY AID PRECIPITATION DEVELOPMENT ACROSS THE PLAINS SUNDAY AFTERNOON AND EVENING. MODELS A BIT DIFFERENT ON THE ARRIVAL OF THE NEXT DISTURBANCE DROPPING ACROSS THE ROCKIES...WITH GFS HAS BEEN BRINGING IT THROUGH MONDAY EVENING...WITH THE ECMWF IS A BIT SLOWER ON TUESDAY. THIS WILL LIKELY LEAD TO ANOTHER ROUND OF DECENT PRECIPITATION FOR THE MOUNTAINS...AND SPREADING EAST INTO THE PLAINS SOMETIME IN THE MONDAY TO TUESDAY TIME FRAME. THIS SYSTEM LOOKS TO BE ACCOMPANIED BY A STRONG COLD FRONT WHICH SHOULD HELP THE PLAINS SEE ANOTHER SHOT FOR PRECIPITATION. MOZLEY && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1049 PM MDT WED AUG 20 2014 ...SIGNIFICANT IMPACT POSSIBLE ON FRIDAY... ISOLATED STORMS WILL DEVELOP OVER THE MOUNTAINS THURSDAY AFTERNOON. STORMS WILL BECOME MORE NUMEROUS AFTER 00Z AS A LOW PRESSURE SYSTEM MOVES INTO COLORADO. ISOLD-SCT STORMS WILL BE POSSIBLE THROUGH THU NIGHT...BUT THE MAIN AVN CONCERN WILL COME ON FRIDAY AS THE UPPER LEVEL STORM SYSTEM MOVES THROUGH. WIDESPREAD PRECIP AND STORMS WITH THE POTENTIAL FOR HEAVY RAIN AND PERSISTENT MVFR-IFR CIGS WILL BE POSSIBLE FROM FRI 15-18Z ON THROUGH FRI EVENING AND POSSIBLY INTO SAT MORNING...ESPECIALLY EAST OF THE SANGRES AND RAMPARTS. ROSE && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...ROSE SHORT TERM...28 LONG TERM...MOZLEY AVIATION...ROSE
AREA FORECAST DISCUSSION
NWS ALBANY NY
638 PM EDT THU AUG 21 2014 .SYNOPSIS... A SLOW MOVING UPPER LEVEL LOW OVER THE EASTERN GREAT LAKES REGION WILL CONTINUE TO BRING SHOWERS AND THUNDERSTORMS...SOME WITH LOCALLY HEAVY RAIN...AS IT DRIFTS EASTWARD THROUGH TONIGHT. THE UPPER LEVEL LOW WILL TRACK OFF THE COAST TOMORROW WITH A FEW LINGERING SHOWERS AND COOL TEMPERATURES OVER THE AREA. IMPROVING CONDITIONS ARE EXPECTED OVER THE WEEKEND AS HIGH PRESSURE BUILDS AT ALL LEVELS OF THE ATMOSPHERE FROM QUEBEC INTO THE NORTHEAST. IT WILL BRING INCREASING AMOUNTS OF SUNSHINE AND WARMER TEMPERATURES INTO NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS OF 357 PM EDT...AN UPPER LEVEL LOW IS CURRENTLY SITUATED WEST OF THE REGION JUST TO THE NORTH OF LAKE ONTARIO. WITH A MOIST AIR MASS IN PLACE...THERE IS PLENTY OF FORCING IN PLACE TO ALLOW FOR SHOWERS AND THUNDERSTORMS TO CONTINUE ACROSS THE REGION THROUGH THE EVENING HOURS.. WITH PLENTY OF CLOUD COVER IN PLACE...INSTABILITY IS LIMITED...WHICH IS HELPING KEEP THE THREAT FOR SEVERE WEATHER LOW. HOWEVER...WITH PWATS ABOVE NORMAL /AROUND 1.63 INCHES FROM THIS MORNINGS KALY SOUNDING/...DEW POINTS INTO THE 60S...AND HIGH FZL LEVELS /FZL LEVELS AROUND 12000 FT/....THE THREAT FOR HEAVY RAINFALL WILL BE POSSIBLE WITH ANY SHOWER OR THUNDERSTORM...AS WARM RAIN PROCESSES WILL DOMINATE. THE RADAR HAS ALREADY SHOWN SEVERAL SLOW MOVING LOW TOPPED STORMS...WITH HEAVY ECHOES LOCATED TOWARDS THE BOTTOMS OF THE STORM...INDICATING HEAVY RAINFALL. THIS WILL CONTINUE INTO THE EVENING HOURS...AS THE 3KM HRRR SHOWS DISORGANIZED...BUT LOCALLY HEAVY...SHOWERS/THUNDERSTORMS TO MOVE ACROSS THE REGION FROM WEST TO EAST THROUGH THE LATE EVENING HOURS. WE WILL CONTINUE TO MONITOR FOR THE POTENTIAL FOR LOCALIZED FLOODING. SEE OUR HYDRO DISCUSSION FOR MORE DETAILS. POPS GRADUALLY TAPER DOWN TO CHANCE FOR LATE TONIGHT AS THE CORE OF THE UPPER LEVEL LOW MOVES OVERHEAD...AND THE BEST FORCING STARTS TO SHIFT EAST OF THE AREA. HOWEVER...IT STILL LOOKS TO REMAIN CLOUDY THROUGH THE OVERNIGHT HOURS...WITH MIN TEMPS MAINLY IN THE UPPER 50S TO MID 60S. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... TOMORROW...THE UPPER LEVEL LOW WILL START TO SHIFT OFFSHORE. HOWEVER...CYCLONIC FLOW AROUND THIS SYSTEM WILL CONTINUE TO ALLOW FOR THE THREAT FOR SOME SCATTERED SHOWERS...ESP DURING DAYTIME HEATING. ANY RAINFALL WILL BE MUCH LIGHTER ON FRIDAY...AS THE BEST MOISTURE WILL BE STARTING TO SHIFT SOUTH AND EAST TOWARDS SOUTHERN NEW ENGLAND. IT STILL LOOKS TO STAY FAIRLY CLOUDY WITH THE UPPER LOW NEARBY...SO TEMPS WILL BE HELD DOWN. MAX TEMPS WILL ONLY BE IN THE UPPER 60S TO MID 70S. THE UPPER LEVEL LOW WILL CONTINUE TO MOVE AWAY FROM THE REGION BETWEEN FRIDAY NIGHT AND SATURDAY. A LINGERING SPRINKLE OR SHOWER CANNOT TOTALLY BE RULED OUT OVER THE HIGH TERRAIN...OTHERWISE IT LOOKS TO BE DRY. FINALLY...SOME BREAKS IN THE CLOUDS WILL START TO OCCUR...ESP BY SAT MORNING FROM NORTH TO SOUTH...AS DRIER AIR STARTS TO WORK IN FROM SOUTHERN CANADA. MIN TEMPS FRI NIGHT WILL BE IN THE 50S...WITH HIGHS ON SATURDAY IN THE 70S. UPPER LEVEL RIDGING WILL START TO BUILD INTO THE AREA FOR SATURDAY NIGHT FROM THE GREAT LAKES AND OHIO VALLEY. WITH CLEARING SKIES AND LIGHT WINDS...GOOD RADIATIONAL COOLING CAN BE EXPECTED...ALLOWING FOR TEMPS TO FALL EASILY. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 40S OVER THE ADIRONDACKS TO THE MID 50S IN THE CAPITAL REGION AND MID HUDSON VALLEY. && .LONG TERM /SUNDAY THROUGH THURSDAY/... HIGH PRESSURE DOMINATES THE WEATHER OVER THE REGION SUNDAY THROUGH WEDNESDAY WITH GRADUAL WARMING EACH DAY AS THE HIGH PRESSURE BUILDS OFFSHORE. HIGHS SUNDAY AND MONDAY IN THE MID 70S TO LOWER 80S. HIGHS TUESDAY AND WEDNESDAY IN THE LOWER TO MID 80S...WITH UPPER 70S TO LOWER 80S IN HIGHER TERRAIN. A WEAK COLD FRONT JUST BEGINS TO APPROACH WEDNESDAY NIGHT AND THURSDAY BUT THE LOW LEVEL THERMAL RIDGING SHOULD STILL BE IN PLACE. SO...JUST SOME ISOLATED SHOWERS AND THUNDERSTORMS WEDNESDAY NIGHT AND THURSDAY WITH HIGHS THURSDAY IN THE 80S. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... PRIMARY 500HPA SHORT WV IS MOVING INTO FCA W/ITS ASSOC WK SFC TROF...AND SCT -SHRA/TSTMS ARE EVOLVING INTO MORE WIDESPREAD -SHRA...AND EMBEDDED TSTMS AS THEY ARE MVNG INTO AREAS OF ELEVATED CAPE. CIGS AND OR VSBYS WILL BE MVFR DURING THIS EVENING...WITH AREAS IFR IN TSTMS THIS EVENING...BCMG IFR OVERNIGHT WITH LOWERING CIGS AND AREAS OF FOG FORMING. WINDS WILL BE LIGHT NORTHEAST TO SOUTHEAST THIS EVENING BCMG NEAR CALM OVERNIGHT. FRI THE SFC TROF WILL LINGER NR WESTERN PERIPHERY OF FCA...AS SVRL 500HPA SHORT WVS DROP SE IN WAKE OF THE DEPARTING 500HPA CUTOFF. SCT-BKN -SHRA WILL DIM THROUGH THE DAY AS DRIER AIR FILTERS IN LLVLS FROM HIGH PRESSURE BUILDING SOUTH UNDER 500HPA RIDGE OVER QB. WINDS WILL BCMG LIGHT NE. CIGS/VSBY WILL BE MVFR MUCH OF THE DAY...IMPVG TO VFR TWRDS EVNG. OUTLOOK... FRIDAY NIGHT: LOW OPERATIONAL IMPACT. NO SIG WX. SATURDAY: NO OPERATIONAL IMPACT. NO SIG WX. SATURDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. SUNDAY: NO OPERATIONAL IMPACT. NO SIG WX. SUNDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. MONDAY: NO OPERATIONAL IMPACT. NO SIG WX. MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. TUESDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .FIRE WEATHER... SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON INTO TONIGHT WILL KEEP FIRE WEATHER CONCERNS AT A MINIMUM. RH VALUES WILL BE NEAR 100 PERCENT IN MOST LOCATIONS TONIGHT. WITH CLOUDS AND SCATTERED SHOWERS AROUND TOMORROW...RH VALUES WILL REMAIN ABOVE 70 PERCENT THROUGH THE ENTIRE DAY...WITH LIGHT AND VARIABLE WINDS. && .HYDROLOGY... SHOWERS AND THUNDERSTORMS ARE CURRENTLY MOVING ACROSS THE REGION THANKS TO A SLOW MOVING UPPER LEVEL LOW. THESE SHOWERS AND THUNDERSTORMS ARE RATHER SLOW MOVING...AND WITH PWATS ABOVE NORMAL /1.63 INCHES ON THIS MORNINGS 12Z KALY SOUNDING/...THERE IS THE POTENTIAL FOR HEAVY RAIN IN A SHORT PERIOD OF TIME. SOME AREAS...GENERALLY FROM AROUND AMSTERDAM NORTHEAST ACROSS THE SACANDAGA LAKE AND INTO WESTERN SARATOGA COUNTY...SAW TWO TO FOUR INCHES OF RAIN LAST NIGHT. ELSEWHERE...GROUND CONDITIONS HAVE BEEN RATHER DRY...DUE TO A LACK OF RECENT RAINFALL. AS A RESULT...MOST AREAS WILL BE ABLE TO HANDLE SOME RAINFALL. HOWEVER...IF HEAVY RAIN OCCURS OVER THOSE AREAS THAT SAW RAINFALL LAST NIGHT OR IF RAINFALL REPEATEDLY MOVES OVER THE SAME LOCATION THIS AFTN INTO EVENING...THEN SOME MINOR FLOODING OF URBAN...POOR DRAINAGE AND LOW LYING AREAS MAY OCCUR. AN ISOLATED FLASH FLOOD CANNOT TOTALLY BE RULED OUT...ALTHOUGH ANY POSSIBLE FLOOD ISSUES WOULD LIKELY BE MORE OF THE POOR DRAINAGE/URBAN TYPE CONCERNS. THE THREAT FOR HEAVY RAINFALL WILL END TONIGHT...AS THE BEST FORCING STARTS TO SHIFT AWAY FROM THE AREA. EVEN THOUGH THERE MAY SOME LINGERING RAIN SHOWERS INTO TOMORROW...NO ADDITIONAL HEAVY RAINFALL IS EXPECTED. WHILE THERE MAY BE SOME RISES ON MAIN STREAM RIVERS DUE TO THE RAINFALL...NO FLOODING OF LARGER RIVERS IS EXPECTED. WITH DRY WEATHER RETURNING FOR SUNDAY INTO NEXT WEEK...RIVER LEVELS WILL RECEDE AND/OR HOLD STEADY INTO NEXT WEEK. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...FRUGIS/SNYDER NEAR TERM...FRUGIS SHORT TERM...FRUGIS LONG TERM...NAS AVIATION...IRL/SNYDER FIRE WEATHER...FRUGIS HYDROLOGY...FRUGIS
AREA FORECAST DISCUSSION
NWS ALBANY NY
357 PM EDT THU AUG 21 2014 .SYNOPSIS... A SLOW MOVING UPPER LEVEL LOW OVER THE EASTERN GREAT LAKES REGION WILL CONTINUE TO BRING SHOWERS AND THUNDERSTORMS...SOME WITH LOCALLY HEAVY RAIN...AS IT DRIFTS EASTWARD THROUGH TONIGHT. THE UPPER LEVEL LOW WILL TRACK OFF THE COAST TOMORROW WITH A FEW LINGERING SHOWERS AND COOL TEMPERATURES OVER THE AREA. IMPROVING CONDITIONS ARE EXPECTED OVER THE WEEKEND...WITH INCREASING AMOUNTS OF SUNSHINE AND WARMER TEMPERATURES INTO NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS OF 357 PM EDT...AN UPPER LEVEL LOW IS CURRENTLY SITUATED WEST OF THE REGION JUST TO THE NORTH OF LAKE ONTARIO. WITH A MOIST AIRMASS IN PLACE...THERE IS PLENTY OF FORCING IN PLACE TO ALLOW FOR SHOWERS AND THUNDERSTORMS TO CONTINUE ACROSS THE REGION THROUGH THE EVENING HOURS.. WITH PLENTY OF CLOUD COVER IN PLACE...INSTABILITY IS LIMITED...WHICH IS HELPING KEEP THE THREAT FOR SEVERE WEATHER LOW. HOWEVER...WITH PWATS ABOVE NORMAL /AROUND 1.63 INCHES FROM THIS MORNINGS KALY SOUNDING/...DEWPOINTS INTO THE 60S...AND HIGH FZL LEVELS /FZL LEVELS AROUND 12000 FT/....THE THREAT FOR HEAVY RAINFALL WILL BE POSSIBLE WITH ANY SHOWER OR THUNDERSTORM...AS WARM RAIN PROCESSES WILL DOMINATE. THE RADAR HAS ALREADY SHOWN SEVERAL SLOW MOVING LOW TOPPED STORMS...WITH HEAVY ECHOES LOCATED TOWARDS THE BOTTOMS OF THE STORM...INDICATING HEAVY RAINFALL. THIS WILL CONTINUE INTO THE EVENING HOURS...AS THE 3KM HRRR SHOWS DISORGANIZED...BUT LOCALLY HEAVY...SHOWERS/THUNDERSTORMS TO MOVE ACROSS THE REGION FROM WEST TO EAST THROUGH THE LATE EVENING HOURS. WE WILL CONTINUE TO MONITOR FOR THE POTENTIAL FOR LOCALIZED FLOODING. SEE OUR HYDRO DISCUSSION FOR MORE DETAILS. POPS GRADUALLY TAPER DOWN TO CHANCE FOR LATE TONIGHT AS THE CORE OF THE UPPER LEVEL LOW MOVES OVERHEAD...AND THE BEST FORCING STARTS TO SHIFT EAST OF THE AREA. HOWEVER...IT STILL LOOKS TO REMAIN CLOUDY THROUGH THE OVERNIGHT HOURS...WITH MIN TEMPS MAINLY IN THE UPPER 50S TO MID 60S. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... TOMORROW...THE UPPER LEVEL LOW WILL START TO SHIFT OFFSHORE. HOWEVER...CYCLONIC FLOW AROUND THIS SYSTEM WILL CONTINUE TO ALLOW FOR THE THREAT FOR SOME SCATTERED SHOWERS...ESP DURING DAYTIME HEATING. ANY RAINFALL WILL BE MUCH LIGHTER ON FRIDAY...AS THE BEST MOISTURE WILL BE STARTING TO SHIFT SOUTH AND EAST TOWARDS SOUTHERN NEW ENGLAND. IT STILL LOOKS TO STAY FAIRLY CLOUDY WITH THE UPPER LOW NEARBY...SO TEMPS WILL BE HELD DOWN. MAX TEMPS WILL ONLY BE IN THE UPPER 60S TO MID 70S. THE UPPER LEVEL LOW WILL CONTINUE TO MOVE AWAY FROM THE REGION BETWEEN FRIDAY NIGHT AND SATURDAY. A LINGERING SPRINKLE OR SHOWER CANNOT TOTALLY BE RULED OUT OVER THE HIGH TERRAIN...OTHERWISE IT LOOKS TO BE DRY. FINALLY...SOME BREAKS IN THE CLOUDS WILL START TO OCCUR...ESP BY SAT MORNING FROM NORTH TO SOUTH...AS DRIER AIR STARTS TO WORK IN FROM SOUTHERN CANADA. MIN TEMPS FRI NIGHT WILL BE IN THE 50S...WITH HIGHS ON SATURDAY IN THE 70S. UPPER LEVEL RIDGING WILL START TO BUILD INTO THE AREA FOR SATURDAY NIGHT FROM THE GREAT LAKES AND OHIO VALLEY. WITH CLEARING SKIES AND LIGHT WINDS...GOOD RADIATIONAL COOLING CAN BE EXPECTED...ALLOWING FOR TEMPS TO FALL EASILY. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 40S OVER THE ADIRONDACKS TO THE MID 50S IN THE CAPITAL REGION AND MID HUDSON VALLEY. && .LONG TERM /SUNDAY THROUGH THURSDAY/... HIGH PRESSURE DOMINATES THE WEATHER OVER THE REGION SUNDAY THROUGH WEDNESDAY WITH GRADUAL WARMING EACH DAY AS THE HIGH PRESSURE BUILDS OFFSHORE. HIGHS SUNDAY AND MONDAY IN THE MID 70S TO LOWER 80S. HIGHS TUESDAY AND WEDNESDAY IN THE LOWER TO MID 80S...WITH UPPER 70S TO LOWER 80S IN HIGHER TERRAIN. A WEAK COLD FRONT JUST BEGINS TO APPROACH WEDNESDAY NIGHT AND THURSDAY BUT THE LOW LEVEL THERMAL RIDGING SHOULD STILL BE IN PLACE. SO...JUST SOME ISOLATED SHOWERS AND THUNDERSTORMS WEDNESDAY NIGHT AND THURSDAY WITH HIGHS THURSDAY IN THE 80S. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... A MIXTURE OF VFR/MVFR FLYING CONDITIONS ARE GENERALLY EXPECTED AT THE TAF SITES THIS AFTERNOON BEFORE LOWERING TO MVFR/IFR TONIGHT. THIS AFTERNOON...AN AREA OF LOW PRESSURE AND ITS ASSOCIATED FRONTAL BOUNDARY WILL CONTINUE TO SLOWLY PUSH ACROSS THE REGION THIS AFTERNOON...WITH A MIXTURE OF VFR/MVFR CEILINGS AND VISIBILITIES EXPECTED. PERIODS OF SHOWERS AND A FEW ISOLATED THUNDERSTORMS WILL BE POSSIBLE...WITH TEMPO GROUPS INDICATING PERIODS OF PRIMARILY MVFR AT THE TAF SITES ASSOCIATED WITH THE SHOWERS/STORMS WITH EVEN SOME IFR CEILINGS POSSIBLE AT KGFL AND KPSF. THE GREATEST THREAT FOR SHOWERS/STORMS APPEARS TO BE BETWEEN 20Z AND 02Z THIS AFTERNOON/EARLY EVENING. WINDS WILL BE LIGHT AND VARIABLE GENERALLY LESS THAN 5 KNOTS. TONIGHT INTO FRIDAY...AS THE LOW PRESSURE SYSTEM CONTINUES TO SLOWLY MOVE ACROSS THE AREA...SHOWERS WILL CONTINUE TO LINGER INTO THE OVERNIGHT HOURS AS FLYING CONDITIONS FALL TO MVFR/IFR. AT THIS TIME THE GREATEST LIKELIHOOD FOR IFR IS AT KGFL AND KPSF...ALTHOUGH CANNOT RULE OUT A PERIOD OF IFR STRATUS AT KALB AND KPOU AFTER 06Z AS WELL. SHOWER ACTIVITY IS EXPECTED TO WANE AFTER 06Z AT KGFL AND KALB...BUT CONTINUE TO LINGER THROUGH THE REMAINDER OF THE NIGHT AT KPOU AND KPSF. KEPT IFR STRATUS OUT OF KALB AND KPOU FOR THIS TAF ISSUANCE AS CONFIDENCE WAS NOT HIGH ENOUGH TO INCLUDE IN TAFS. MVFR CEILINGS ARE EXPECTED TO LINGER THROUGH THE REMAINDER OF THE TAF PERIOD AFTER 12Z FRIDAY WITH A GRADUALLY DECREASING CHANCE FOR SHOWERS AS DRIER AIR BEGINS TO BUILD INTO THE REGION. WINDS TONIGHT WILL TREND TOWARDS CALM BEFORE BECOMING LIGHT AND VARIABLE FRIDAY AROUND 5 KNOTS. OUTLOOK... FRIDAY NIGHT: LOW OPERATIONAL IMPACT. NO SIG WX. SATURDAY: NO OPERATIONAL IMPACT. NO SIG WX. SATURDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. SUNDAY: NO OPERATIONAL IMPACT. NO SIG WX. SUNDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. MONDAY: NO OPERATIONAL IMPACT. NO SIG WX. MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. TUESDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .FIRE WEATHER... SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON INTO TONIGHT WILL KEEP FIRE WEATHER CONCERNS AT A MINIMUM. RH VALUES WILL BE NEAR 100 PERCENT IN MOST LOCATIONS TONIGHT. WITH CLOUDS AND SCATTERED SHOWERS AROUND TOMORROW...RH VALUES WILL REMAIN ABOVE 70 PERCENT THROUGH THE ENTIRE DAY...WITH LIGHT AND VARIABLE WINDS. && .HYDROLOGY... SHOWERS AND THUNDERSTORMS ARE CURRENTLY MOVING ACROSS THE REGION THANKS TO A SLOW MOVING UPPER LEVEL LOW. THESE SHOWERS AND THUNDERSTORMS ARE RATHER SLOW MOVING...AND WITH PWATS ABOVE NORMAL /1.63 INCHES ON THIS MORNINGS 12Z KALY SOUNDING/...THERE IS THE POTENTIAL FOR HEAVY RAIN IN A SHORT PERIOD OF TIME. SOME AREAS...GENERALLY FROM AROUND AMSTERDAM NORTHEAST ACROSS THE SACANDAGA LAKE AND INTO WESTERN SARATOGA COUNTY...SAW TWO TO FOUR INCHES OF RAIN LAST NIGHT. ELSEWHERE...GROUND CONDITIONS HAVE BEEN RATHER DRY...DUE TO A LACK OF RECENT RAINFALL. AS A RESULT...MOST AREAS WILL BE ABLE TO HANDLE SOME RAINFALL. HOWEVER...IF HEAVY RAIN OCCURS OVER THOSE AREAS THAT SAW RAINFALL LAST NIGHT OR IF RAINFALL REPEATEDLY MOVES OVER THE SAME LOCATION THIS AFTN INTO EVENING...THEN SOME MINOR FLOODING OF URBAN...POOR DRAINAGE AND LOW LYING AREAS MAY OCCUR. AN ISOLATED FLASH FLOOD CANNOT TOTALLY BE RULED OUT...ALTHOUGH ANY POSSIBLE FLOOD ISSUES WOULD LIKELY BE MORE OF THE POOR DRAINAGE/URBAN TYPE CONCERNS. THE THREAT FOR HEAVY RAINFALL WILL END TONIGHT...AS THE BEST FORCING STARTS TO SHIFT AWAY FROM THE AREA. EVEN THOUGH THERE MAY SOME LINGERING RAIN SHOWERS INTO TOMORROW...NO ADDITIONAL HEAVY RAINFALL IS EXPECTED. WHILE THERE MAY BE SOME RISES ON MAIN STREAM RIVERS DUE TO THE RAINFALL...NO FLOODING OF LARGER RIVERS IS EXPECTED. WITH DRY WEATHER RETURNING FOR SUNDAY INTO NEXT WEEK...RIVER LEVELS WILL RECEDE AND/OR HOLD STEADY INTO NEXT WEEK. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...FRUGIS NEAR TERM...FRUGIS SHORT TERM...FRUGIS LONG TERM...NAS AVIATION...IRL FIRE WEATHER...FRUGIS HYDROLOGY...FRUGIS
AREA FORECAST DISCUSSION
NWS ALBANY NY
135 PM EDT THU AUG 21 2014 .SYNOPSIS... A SLOW MOVING UPPER LEVEL LOW OVER THE GREAT LAKES REGION WILL IMPACT THE FORECAST AREA WITH SHOWERS AND THUNDERSTORM AS IT DRIFTS EASTWARD THROUGH TONIGHT. THE UPPER LEVEL LOW WILL TRACK OFF THE COAST TOMORROW WITH A FEW LINGERING SHOWERS AND COOL TEMPERATURES OVER THE AREA. IMPROVING CONDITIONS ARE EXPECTED OVER THE WEEKEND...WITH INCREASING AMOUNTS OF MORE SUNSHINE AND WARMER TEMPERATURES INTO NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 135 PM EDT...LATEST REGIONAL MOSAIC RADAR SHOWS AREAS OF MAINLY SCATTERED SHOWERS AND THUNDERSTORMS OVER THE REGION. THE BIGGEST CONCENTRATION IS WEST OF THE AREA TOWARDS CENTRAL NY...THE FINGER LAKES...AND THE SOUTHERN TIER. OVER THE NEXT FEW HOURS...THIS ACTIVITY WILL SPREAD ACROSS EASTERN NY AND EVENTUALLY WESTERN NEW ENGLAND FROM THE WEST TO EAST...AS SHOWN IN THE LATEST 3KM HRRR GUIDANCE. ANY THUNDERSTORMS MAY CONTAIN A BRIEF PERIOD OF HEAVY RAINFALL...AND IF THIS OCCURS OVER ANY AREAS THAT SAW SIGNIFICANT RAIN LAST NIGHT /SUCH AS THE SACANDAGA AREA/...THEN THERE MAY BE SOME MINOR FLOODING...ESP OF LOW LYING AND URBAN AREAS. OTHERWISE...OUTSIDE THE ON AND OFF SHOWERS/THUNDERSTORMS...IT WILL REMAIN FAIRLY CLOUDY OVER THE AREA THIS AFTERNOON WITH JUST A FEW BREAKS OR LIGHTENING UP OF THE SKIES...ALONG WITH CONTINUED MUGGY CONDITIONS. TEMPS ARE ALREADY CLOSE TO THEIR HIGHS FOR THE DAY AND WILL EITHER HOLD STEADY OR ONLY RISE A DEGREE OR TWO MORE. HIGHS ARE GENERALLY EXPECTED TO BE IN THE 70S...WITH UPPER 60S OVER THE HIGH TERRAIN OF NEW ENGLAND. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... THE SYSTEM WILL MOVE OFF THE COAST TONIGHT AND EARLY FRIDAY...WITH DRIER AIR WORKING SOUTHWESTWARD INTO THE REGION FROM A SPRAWLING HIGH PRESSURE SYSTEM OVER THE CANADIAN MARITIMES. POPS ARE SLOWLY FORECAST TO DECREASE TONIGHT AND FRIDAY...WITH MAINLY JUST SLIGHT CHANCE POPS ACROSS THE REGION BY FRIDAY AFTERNOON. AS THE DRIER AIR CONTINUES TO PUSH INTO THE REGION AND HIGH PRESSURE AT ALL LEVELS OF THE ATMOSPHERE BEGINS TO BUILD INTO THE REGION...CLOUDS WILL SLOWLY DECREASE LATE FRIDAY THROUGH FRIDAY NIGHT...WITH PARTLY SUNNY SKIES ON SATURDAY. LOWS TONIGHT WILL BE IN THE MID 50S TO LOWER 60S. HIGHS FRIDAY MID 60S TO LOWER 70S. LOWS FRIDAY NIGHT IN THE 50S. HIGHS SATURDAY IN THE 70S. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A NICE STRETCH OF WEATHER IS EXPECTED IN THE LONG TERM FROM THE WEEKEND INTO THE MIDDLE OF NEXT WEEK WITH TEMPS RISING TO SLIGHTLY ABOVE NORMAL LEVELS AS WE ENTER THE LAST WEEK OF AUGUST. WPC GUIDANCE/ECMWF/ENSEMBLES/GFS ARE IN PRETTY GOOD AGREEMENT HIGH PRESSURE WILL BUILD IN OVER NY AND NEW ENGLAND FROM SRN QUEBEC AND NRN NEW ENGLAND SAT NIGHT...AND BE CENTERED OVER THE NORTHEAST SUNDAY TO TUESDAY...AS A MID AND UPPER LEVEL RIDGE BUILDS IN FROM THE MS RIVER VALLEY AND PLAINS. AN UPPER LEVEL TROUGH SETS UP DOWN STREAM OVER THE CANADIAN MARITIMES...AND LARGE-SCALE SYNOPTIC SUBSIDENCE WILL INFLUENCE THE WEATHER OVER THE LONG TERM STRETCH. A WEAK COLD FRONTAL BOUNDARY WITH LIMITED LOW-LEVEL MOISTURE TO WORK WITH MAY MOVE ACROSS THE REGION WEDNESDAY AFTERNOON INTO THURSDAY. ONLY A SLIGHT CHC OF SHOWERS WAS ADDED TO THE GRIDDED FORECASTS WED PM INTO WED NIGHT NW OF THE CAPITAL REGION. TEMPS WILL START OUT COOLER THAN NORMAL FOR THE CLOSE OF THE WEEKEND WITH 50S FOR LOWS...AND HIGHS IN THE LOWER TO M70S IN THE VALLEYS...AND M60S TO L70S OVER THE HILLS AND MTNS. MONDAY INTO TUESDAY...H850 TEMP MODERATE TO +13C TO +14C WITH DECENT MIXING...AS SFC HIGH PRESSURE DRIFTS SLIGHTLY SOUTH AND WEST OF UPSTATE NY AND NEW ENGLAND. EXPECT HIGHS TO REACH THE U70S TO L80S IN THE VALLEY AREAS...AND LOWER TO M70S OVER THE MTNS. LOWS WILL BE IN THE 50S TO L60S. WEDNESDAY LOOKS LIKE THE WARMEST AFTERNOON WITH M70S TO L80S FOR HIGHS...AND HUMIDITY LEVELS CREEPING UP WITH SFC DEWPTS IN THE M50S TO L60S. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... A MIXTURE OF VFR/MVFR FLYING CONDITIONS ARE GENERALLY EXPECTED AT THE TAF SITES THIS AFTERNOON BEFORE LOWERING TO MVFR/IFR TONIGHT. THIS AFTERNOON...AN AREA OF LOW PRESSURE AND ITS ASSOCIATED FRONTAL BOUNDARY WILL CONTINUE TO SLOWLY PUSH ACROSS THE REGION THIS AFTERNOON...WITH A MIXTURE OF VFR/MVFR CEILINGS AND VISIBILITIES EXPECTED. PERIODS OF SHOWERS AND A FEW ISOLATED THUNDERSTORMS WILL BE POSSIBLE...WITH TEMPO GROUPS INDICATING PERIODS OF PRIMARILY MVFR AT THE TAF SITES ASSOCIATED WITH THE SHOWERS/STORMS WITH EVEN SOME IFR CEILINGS POSSIBLE AT KGFL AND KPSF. THE GREATEST THREAT FOR SHOWERS/STORMS APPEARS TO BE BETWEEN 20Z AND 02Z THIS AFTERNOON/EARLY EVENING. WINDS WILL BE LIGHT AND VARIABLE GENERALLY LESS THAN 5 KNOTS. TONIGHT INTO FRIDAY...AS THE LOW PRESSURE SYSTEM CONTINUES TO SLOWLY MOVE ACROSS THE AREA...SHOWERS WILL CONTINUE TO LINGER INTO THE OVERNIGHT HOURS AS FLYING CONDITIONS FALL TO MVFR/IFR. AT THIS TIME THE GREATEST LIKELIHOOD FOR IFR IS AT KGFL AND KPSF...ALTHOUGH CANNOT RULE OUT A PERIOD OF IFR STRATUS AT KALB AND KPOU AFTER 06Z AS WELL. SHOWER ACTIVITY IS EXPECTED TO WANE AFTER 06Z AT KGFL AND KALB...BUT CONTINUE TO LINGER THROUGH THE REMAINDER OF THE NIGHT AT KPOU AND KPSF. KEPT IFR STRATUS OUT OF KALB AND KPOU FOR THIS TAF ISSUANCE AS CONFIDENCE WAS NOT HIGH ENOUGH TO INCLUDE IN TAFS. MVFR CEILINGS ARE EXPECTED TO LINGER THROUGH THE REMAINDER OF THE TAF PERIOD AFTER 12Z FRIDAY WITH A GRADUALLY DECREASING CHANCE FOR SHOWERS AS DRIER AIR BEGINS TO BUILD INTO THE REGION. WINDS TONIGHT WILL TREND TOWARDS CALM BEFORE BECOMING LIGHT AND VARIABLE FRIDAY AROUND 5 KNOTS. OUTLOOK... FRIDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA. FRIDAY NIGHT-MONDAY: NO OPERATIONAL IMPACT. NO SIG WX. && .FIRE WEATHER... SCATTERED TO NUMEROUS SHOWERS WILL PERSIST THROUGH TONIGHT. IT WILL REMAIN MOSTLY CLOUDY AND DAMP FOR FRIDAY WITH A FEW LINGERING SHOWERS POSSIBLE. RH VALUES WILL BE ELEVATED THE NEXT COUPLE OF DAYS...GENERALLY OVER 60 PERCENT...SOMETIMES CLOSE TO 100 PERCENT...DUE TO THE WET WEATHER AND CLOUDY CONDITIONS. THE WIND WILL VARIABLE TO SOUTHEASTERLY AT 5-10 MPH TODAY THROUGH FRIDAY. && .HYDROLOGY... NO HYDRO PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS AT THIS TIME. A SLOW MOVING WEAK LOW PRESSURE SYSTEM OVER THE GREAT LAKES REGION WILL IMPACT THE FORECAST AREA WITH SHOWERS AND POSSIBLY A STRAY THUNDERSTORM AS IT DRIFTS EASTWARD OVERNIGHT INTO THURSDAY NIGHT. THE LOW WILL TRACK OFF THE COAST FRIDAY. AS OF 400 AM...RADAR INDICATES THAT LOCALIZED AMOUNTS OF UP TO THREE INCHES OF RAIN HAD FALLEN SINCE WEDNESDAY FROM THE MOHAWK VALLEY INTO THE SARATOGA REGION. GENERALLY A THIRD OF AN INCH TO ONE AND A HALF INCHES OF RAIN HAD FALLEN ACROSS THE NORTHWEST THIRD OF THE FORECAST AREA...WITH MUCH LOWER AMOUNTS ELSEWHERE. THIS SYSTEM WILL CONTINUE TO PRODUCE AREAS OF SHOWERS THROUGH TONIGHT...WITH ADDITIONAL RAINFALL AMOUNTS OF A HALF TO ONE INCH IN MANY AREAS...BUT LOCALIZED AMOUNTS OF ANOTHER TWO TO THREE INCHES ARE POSSIBLE. DUE TO LOW RIVER LEVELS AND FAIRLY DRY SOIL CONDITIONS BEFORE THE RAIN BEGAN...THE IMPACT ON AREA STREAMS AND RIVERS WILL GENERALLY BE MINOR AND NO RIVER FLOODING IS EXPECTED. BE. HOWEVER...ANY SHOWER OR THUNDERSTORM COULD PRODUCE LOCALIZED HEAVY RAINFALL AMOUNTS...WHICH COULD RESULT IN SIGNIFICANT PONDING OF WATER ON ROADWAYS AND MINOR FLOODING IN AREAS OF POOR DRAINAGE. THERE COULD BE SOME ADDITIONAL SHOWERS ON FRIDAY BUT THESE SHOULD BE LIGHT. DRY WEATHER RETURNS BY THE WEEKEND AND FOR MUCH OF NEXT WEEK. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...FRUGIS NEAR TERM...FRUGIS SHORT TERM...GJM LONG TERM...WASULA AVIATION...IRL FIRE WEATHER...GJM HYDROLOGY...GJM
AREA FORECAST DISCUSSION
NWS TAUNTON MA
140 AM EDT THU AUG 21 2014 .SYNOPSIS... WET WEATHER LIKELY IMPACTING WESTERN AND CENTRAL PORTIONS OF NEW ENGLAND BEGINNING TONIGHT AND CONTINUING THROUGH FRIDAY. DRIER AND COOLER WEATHER FOLLOWS INTO THE WEEKEND. A WARM-UP IS POSSIBLE INTO NEXT WEEK PRIOR TO AN UNSETTLED PATTERN AHEAD OF A FRONTAL BOUNDARY SWEEPING SOUTH OUT OF CANADA. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 130 AM UPDATE... MOST FORECAST PARAMETERS ON TRACK. ALTHOUGH SOME RAIN IS JUST BEGINNING TO BREAK THE WRN MOST BORDER OF BOX CWA. INCREASED POPS IN THIS REGION BY JUST A BIT. PREVIOUS DISCUSSION... PREVIOUS DISCUSSION... HEIGHTS FALL AS THE GREAT LAKES LOW SHIFTS INTO THE NE CONUS... TROUGHING TOWARDS THE W-E AXIS OF LOW PRESSURE AND INSTABILITY OFF THE MID-ATLANTIC. LABRADOR RIDGE OF HIGH PRESSURE ALONG WITH DRY AIR AND SUBSIDENCE WILL PERSIST INTO NEW ENGLAND...AHEAD OF WHICH THE COLLISION TOWARDS LOW PRESSURE AND HIGHER THETA-E AIR WILL RESULT IN A DEFINED AREA OF CONVERGENCE ACROSS PA/NY...AND POSSIBLY SE MA. TO THE W...INCREASING THETA-E MOISTURE LOADING THE MID- TO UPPER- LEVELS WILL LIKELY RESULT IN INCREASING AND THICKENING CLOUDS W TO E. BUT STILL A LOT OF DRY AIR TO OVERCOME BELOW H6-7 ESPECIALLY OVER E NEW ENGLAND WITH THE INVERTED RIDGE. NOTING THE WARM FRONT WELL W ACROSS PA/NY ALONG WITH PARENT DYNAMICS AND LOW-LEVEL CONVERGENCE... BEST CHANCES FOR SHOWERS WITHIN AREAS OF DEEP-LAYER ASCENT SHOULD BE NO FURTHER E OF THE CT-RIVER VALLEY. EXPECTING SPRINKLES. ITS LIKELY BETTER ACTIVITY WILL BE WELL N/W PARENT WITH BETTER MOISTURE CONVERGENT ALONG THE NOSE OF THE H925-85 JET INTO THE ADIRONDACKS ON UP INTO ONTARIO/QUEBEC AS DESTABILIZATION CONCLUDES. PREFER CHANCE POPS ONLY INTO THE CT-VALLEY. TO THE SE...TROUGHING SE BACKS LOW PRESSURE AND HIGHER THETA-E AIR OFF THE E-W STALLED FRONT OFF THE MID-ATLANTIC. THE CONVERGENCE OF AIR MASSES ALONG AN INVERTED-TROUGH TO THE AFOREMENTIONED LOW WILL BE THE FOCUS FOR POTENTIAL HEAVY RAIN...EVEN THUNDERSTORMS. MAINLY A WARM-RAIN PROCESS WITH PWATS UP TO 1.75 INCHES. WHILE A CONSISTENT SIGNAL AMONG FORECAST SOLUTIONS...OUTCOMES VARY SLIGHTLY LIKELY DUE TO THE STRENGTH OF INVERTED-RIDGE. WILL GO WITH LIKELY POPS FOR NANTUCKET WITH CHANCE POPS INTO THE CAPE AND SE MA. THE SETUP IS ALREADY COMING TOGETHER SEEN PER IR/VISIBLE SATELLITE...BUT A LOT OF UNCERTAINTY BETWEEN THE STRENGTH OF THE RIDGE AND THE ZONE SETUP OF CONVERGENCE. WRF/NAM THE MOST ROBUST WITH OUTCOMES. 17Z HRRR/18Z RAP HAS ACTIVITY MISSING NANTUCKET. NOT ENOUGH CONFIDENCE TO GO HIGH CATEGORICAL POPS. THICKER CLOUDS ACROSS THE REGION WILL LIMIT RADIATIONAL COOLING. ANTICIPATING A MORE MILD NIGHT OVER MUCH OF THE REGION WITH LOWS AROUND THE UPPER-50S. COOLEST CONDITIONS EXPECTED ACROSS E/SE MA UNDER LIGHT AND VARIABLE WINDS AND THE BETTER CHANCE OF RADIATING OUT...LOWS AROUND THE MID-50S. FOR SUCH AREAS THERE IS ALSO THE POSSIBILITY OF PATCHY GROUND FOG. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... THURSDAY INTO THURSDAY NIGHT... CLOSED LOW OUT OF THE GREAT LAKES GRADUALLY WOBBLES INTO NEW ENGLAND THROUGH THE FORECAST PERIOD. THE SYSTEM WEAKENS AS IT TRANSITIONS SW RE-EMERGING ALONG THE W-E FRONTAL BOUNDARY OFF THE MID-ATLANTIC TOWARDS THE BETTER THERMAL-INSTABILITY AXIS. SUBSEQUENT RISING HEIGHTS ALLOWS RIDGING TO BUILD SW THURSDAY NIGHT. WHILE HIGHER THETA-E AIR STREAMS ACROSS THE REGION WITHIN THE MID-LEVELS...E-FLOW WITHIN LOW-LEVELS FROM THE LABRADOR HIGH UNDERCUTS MOISTURE LOADING ALOFT KEEPING CONDITIONS FAIRLY STABLE AND DRY...LIKELY TO ERODE ACTIVITY S AND W. AS THE LOW TRANSITIONS AND WEAKENS...PRECIPITATION ACROSS THE CAPE AND ISLANDS CONCLUDES WITH THE STRENGTHENING INFLUENCE OF THE RIDGE. ENERGY AND MOISTURE PARENT TO THE LOW IS ANTICIPATED TO SWEEP MAINLY ACROSS SW NEW ENGLAND...PERHAPS SW OF A LINE FROM BOSTON TO KEENE NH. WILL KEEP THESE AREAS UNDER CHANCE POPS ACCORDINGLY WITH ASCENT AND LIKELY CONVERGENCE AGAINST THE SW BUILDING RIDGE. WITH THE UNDERCUTTING DRY AND STABLE AIRMASS OFF THE OCEAN WITH THE STRENGTHENING RIDGE LATE...AND CLOUDS THROUGH THE PERIOD LIMITING DESTABILIZATION...NOT EXPECTING ANY THUNDER. HIGHS AROUND THE MID- TO UPPER-70S DURING THE DAY WITH LOWS AROUND THE UPPER-50S. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... HIGHLIGHTS... * QUIET WEATHER EXPECTED THROUGH MUCH OF THE LONG TERM * UNCERTAINTY INCREASES MIDDLE OF NEXT WEEK WITH AN APPROACHING FRONT. MODELS ARE IN GOOD AGREEMENT THROUGH MUCH OF THE LONG TERM. A PERSISTENT UPPER LEVEL TROUGH OVER THE NORTHEAST WILL SLOWLY MAKE ITS WAY EAST...MOVING JUST OFFSHORE THIS WEEKEND AS AN UPPER LEVEL RIDGE TRIES TO PUSH NORTHEASTWARD FROM THE SOUTHERN U.S. THE UPPER TROUGH IS RATHER PERSISTENT THOUGH AND EACH MODEL RUN KEEPS THE TROUGH JUST OFFSHORE LONGER AND LONGER. COOLER...LESS SEASONABLE WEATHER IS EXPECTED WHILE HIGH PRESSURE IN QUEBEC WILL KEEP THINGS RELATIVELY DRY. MODELS ARE INDICATING SOME POTENTIAL FOR QPF EACH DAY THROUGH THE WEEKEND BUT GIVEN THE LACK OF ANY FORCING MECHANISM AND VERY LITTLE MOISTURE TO SPEAK OF... THINKING THIS COULD BE CONVECTIVE FEEDBACK RATHER THAN A DEPICTION OF ANYTHING LIKELY TO OCCUR. THE HIGH WILL SINK SOUTH THROUGH THE WEEKEND INTO EARLY NEXT WEEK...EVENTUALLY DROPPING SOUTH AND EAST OF SOUTHERN NEW ENGLAND AND RETURNING US TO A MORE WESTERLY FLOW. LOW PRESSURE IN ONTARIO MAY EVENTUALLY MOVE EASTWARD INTO QUEBEC BRINGING A COLD FRONT THROUGH SOUTHERN NEW ENGLAND WEDNESDAY OR THURSDAY. THIS IS WHERE MODELS START TO DIVERGE A BIT WITH THE ECMWF A BIT QUICKER THAN THE GFS WITH THE APPROACH OF THE FRONT. DEPENDING ON AVAILABLE MOISTURE THIS MAY INITIATE A FEW SHOWERS AND THUNDERSTORMS AHEAD OF THE FRONT. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM...THROUGH FRIDAY...MODERATE CONFIDENCE. THROUGH 12Z... MAINLY VFR EXCEPT SOME IFR/MVFR POSSIBLE AT SOME SITES ACROSS E MA IN FOG. SOME MVFR CIGS POSSIBLE MAINLY ACROSS ACK AND THE OUTER ARM OF CAPE COD. TODAY AND TONIGHT... MAINLY VFR. EXCEPT FOR ACK...MOST OF THE RAIN REMAINS TO THE W THROUGH THE DAY. THEN...BETTER CHANCE FOR SHOWERS ACROSS WRN MA/CT/NH OVERNIGHT ESPECIALLY...WITH OCCASIONAL MVFR CONDITIONS POSSIBLE. SOME LOW MVFR/IFR POSSIBLE MAINLY ACROSS THE E COAST. FRI... CONDITIONS IMPROVE THROUGH THE DAY. SOME MVFR/IFR POSSIBLE IN THE MORNING GIVES WAY TO VFR THROUGH THE DAY...BUT MAY TAKE MOST OF THE DAY ALONG THE E COAST. KBOS TERMINAL...MODERATE CONFIDENCE. MAIN CONCERN IS WHETHER A BRIEF PERIOD OF IFR CONDITIONS MOVE IN EARLY THIS MORNING BRIEFLY...AND THEN RETURNS LATE THU NIGHT. OTHERWISE VFR WITH E FLOW ASSISTED BY SEABREEZES EXPECTED. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. -RA CHANCES BEGIN TOWARDS THURSDAY MORNING ALONG WITH LOW-END VFR CIGS. MVFR CIGS POSSIBLE THOUGH MAINLY TONIGHT...BUT REMAINS LOW-CONFIDENCE AT THIS TIME. OUTLOOK...FRIDAY THROUGH MONDAY... MODERATE CONFIDENCE. MAINLY VFR. LOW PROBABILITY OF PATCHY MVFR/IFR FOG EACH NIGHT. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT-TERM...THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE. CLOSELY MONITORING THE SE WATERS. MAY SEE A SURGANCE OF RAIN ALONG WITH VISIBILITY IMPACTS DURING THE OVERNIGHT HOURS INTO THURSDAY ALONG WITH AN INCREASE IN E-NE FLOW AS AN AREA OF LOW PRESSURE DEVELOPS WELL OUT TO SEA. QUITE POSSIBLE WIND GUST UP TO 25 KTS...BUT WILL HOLD AROUND 20 KTS FOR NOW. WILL KEEP SEAS AROUND 3 TO 4 FEET. CONDITIONS RELAX INTO FRIDAY MORNING. OUTLOOK...FRIDAY THROUGH MONDAY... MODERATE TO HIGH CONFIDENCE. QUIET BOATING WEATHER IS EXPECTED THROUGH MUCH OF THE PERIOD WITH HIGH PRESSURE ACROSS THE REGION. LOW PROBABILITY OF PATCHY OVERNIGHT FOG LIMITING VISIBILITIES. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...RLG/SIPPRELL NEAR TERM...DOODY/SIPPRELL SHORT TERM...SIPPRELL LONG TERM...RLG AVIATION...KJC/DOODY/RLG MARINE...RLG/SIPPRELL
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
334 AM EDT THU AUG 21 2014 .SYNOPSIS... THE REGION WILL SEE AN ACTIVE WEATHER PATTERN FOR THE NEXT TWO DAYS AS ONE AREA OF HIGH PRESSURE REMAINS OVER THE DEEP SOUTH, WHILE ANOTHER IS SITUATED OVER THE HUDSON BAY. THE CANADIAN HIGH WILL EVENTUALLY BUILD SOUTH OVER THE REGION BY LATE THIS WEEKEND AND REMAIN THE THE MAIN WEATHER FEATURE FOR THE MID ATLANTIC THROUGH MID WEEK NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THERE ARE A COUPLE OF AREAS OF ISOLATED/SCATTERED SHOWERS AROUND THE AREA EARLY THIS MORNING, ALL ASSOCIATED WITH A FEW INDIVIDUAL VORTICITY IMPULSES MOVING THROUGH THE CYCLONIC FLOW ALOFT. THE FIRST IS EXITING OUR AREA TO THE NORTHEAST, AND WILL BRING WITH IT IT`S AREA OF SHOWERS. THE OTHERS ARE LOCATED ACROSS CENTRAL AND WESTERN PENNSYLVANIA. THE HRRR AND RUC HAVE THESE DRIFTING EASTWARD AND MOSTLY DRYING OUT OR LIFTING TO OUR NORTH BEFORE THEY GET HERE. AFTER THESE SHOWERS EARLY THIS MORNING, WE SHOULD GET A PERIOD FROM MID/LATE MORNING INTO THE EARLY AFTERNOON WHERE WE SHOULD BE MOSTLY SHOWER FREE. HOWEVER, AS WE MOVE INTO THE MID TO LATE AFTERNOON, WE EXPECT SHOWERS TO BEGIN TO INCREASE TO OUR WEST AND MOVE INTO OUR AREA. THESE WILL BE ASSOCIATED WITH ANOTHER SHORT WAVE/VORTICITY IMPULSE THAT WILL BE MOVING INTO OUR AREA AS THE MID/UPPER LOW SLOWLY DRIFTS EASTWARD. AT THE SURFACE, AN AREA OF LOW PRESSURE REMAINS ACROSS THE EASTERN GREAT LAKES, WHILE A WEAKENING FRONTAL BOUNDARY EXTENDS SOUTH OF THE LOW. ANOTHER FRONTAL BOUNDARY REMAINS SNAKED FROM WESTERN PENNSYLVANIA SOUTHWARD THROUGH VIRGINIA AND NORTH CAROLINA. NONE OF THESE FEATURES ARE EXPECTED TO MOVE INTO THE AREA TODAY AS THE LOW IS EXPECTED TO REMAIN TO OUR NORTH AND THE FRONTAL BOUNDARY TO OUR SOUTH IS EXPECTED TO REMAIN STATIONARY THROUGH THE DAY. THERE REMAINS SOME INSTABILITY FORECAST TODAY, ALTHOUGH THERE IS NOT MUCH SHEAR OR MUCH OF A WIND FIELD, SO WE DO NOT EXPECT SEVERE WEATHER AT THIS TIME. IF THERE ARE ANY THUNDERSTORMS LATER TODAY, AND IF THEY GROW TALL ENOUGH, SOME GUSTY WINDS COULD BE POSSIBLE AND WITH THE WETBULB AS LOW AS IT IS, SOME SMALL HAIL CANNOT BE RULED OUT. PW VALUES ARE GENERALLY FORECAST AROUND 1.5-1.75 INCHES, SO SOME SHOWERS/STORMS COULD PRODUCE A PERIOD MODERATE TO HEAVY RAINFALL. FOR HIGHS, USED A BLEND OF MAV/MET MOS, MOSGUIDE, AND MIXED 925 MB TEMPS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... WE EXPECT SHOWERS AND POSSIBLY THUNDERSTORMS TO BE ONGOING AT THE START OF THE SHORT TERM PERIOD AS THE VORTICITY IMPULSE WILL BE MOVING THROUGH THE AREA AS THE MID/UPPER LOW CONTINUES TO DRIFT EASTWARD INTO NEW ENGLAND. ALSO, A SECOND AREA OF SURFACE LOW PRESSURE IS FORECAST TO DEVELOP NEAR THE CHESAPEAKE BAY ALONG THE STATIONARY BOUNDARY TO OUR SOUTH AS IT TRIES TO LIFT NORTHWARD INTO OUR SOUTHERN AREAS. THIS MAY KEEP A FOCUS FOR PRECIPITATION OVERNIGHT ACROSS OUR SOUTHERN AREAS WHERE SHOWERS MAY LAST INTO THE EARLY MORNING HOURS OF FRIDAY. AS THE ENERGY FROM THE VORTICITY IMPULSE MOVES AWAY FROM THE AREA, SHOWERS SHOULD MOSTLY END BY DAYBREAK. FOR LOWS, USED A BLEND OF MAV/MET MOS AND MOSGUIDE. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... FRIDAY THROUGH SATURDAY...THE REGION REMAINS UNDER NORTHWEST FLOW AS THE STOUT RIDGE REMAINS OVER THE MISSISSIPPI VALLEY, AND THE OTHER HIGH REMAINS OVER EASTERN CANADA. WITH THE NORTHWEST FLOW, EXPECT A FEW EMBEDDED SHORT WAVE TROUGHS TO BRING CHANCES FOR THUNDERSTORMS THROUGH THIS PERIOD. HOWEVER, THE TIMING OF THE INDIVIDUAL SHORT WAVE TROUGHS REMAINS UNCERTAIN. SUNDAY THROUGH THURSDAY...THE HIGH OVER EASTERN CANADA BUILDS SOUTH. WITH THE ASSOCIATED COLD AIR ADVECTION, COULD SEE HIGHS ESPECIALLY EARLY IN THE WEEKEND 5 TO 10 DEGREES BELOW NORMAL. BY TUESDAY HOWEVER, THE HIGH STARTS TO SHIFT OFF SHORE, LEAVING THE REGION UNDER SOUTHERLY FLOW AND LEADING TO A MODEST WARMING TREND. HOWEVER, ALSO TOWARDS THE END OF THIS FORECAST PERIOD THE GFS AND ECMWF SOLUTIONS DIFFER GREATLY ON THE TIMING OF AN UPPER LEVEL TROUGH AND ASSOCIATED SURFACE COLD FRONT THAT WILL BE PROPAGATING EAST ON THE HEALS OF THE HIGH. STILL, BOTH SOLUTIONS SHOW THESE FEATURES JUST BEYOND THE SEVEN DAY FORECAST. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. OVERALL, WE EXPECT MOSTLY VFR CONDITIONS FOR THE TAF SITES TODAY, ALTHOUGH THERE IS THE POTENTIAL FOR LOWER CONDITIONS LATER TODAY INTO THIS EVENING. A PERIOD OF MVFR CIG AND/OR VSBY IS POSSIBLE EARLY THIS MORNING MAINLY FOR ABE/RDG/MIV, BUT THIS SHOULD RETURN TO VFR BY MID-MORNING. WE EXPECT SCATTERED SHOWERS, AND POSSIBLY THUNDERSTORMS, TO DEVELOP TO OUR WEST TROUGH THE DAY AND MOVE INTO OUR AREA LATER THIS AFTERNOON INTO THIS EVENING AS A DISTURBANCE ALOFT MOVES THROUGH THE AREA. CONFIDENCE IN THUNDERSTORM ACTIVITY OCCURRENCE AND TIMING IS LOW, SO THEY WERE NOT INCLUDED IN THE TAFS AT THIS TIME. THERE IS THE POTENTIAL FOR SOME MODERATE TO HEAVY SHOWERS, SO WE HAVE INCLUDED MODERATE SHOWERS WITH MVFR CONDITIONS LATER TODAY INTO THIS EVENING. ONE MODEL GIVES US VFR THROUGH THE PERIOD, WHILE THE OTHER BRINGS EVERYONE TO IFR. NOT CONFIDENT ON IFR, BUT THINK WE COULD GET SOME LOWER CONDITIONS TEMPORARILY WITH THE HEAVIER SHOWERS. WINDS TODAY SHOULD BE MOSTLY SOUTH TO SOUTHEAST AROUND 5 TO 10 KNOTS. OUTLOOK... FRIDAY AND SATURDAY...MOSTLY VFR. ISOLATED TO SCATTERED TSRA ARE POSSIBLE ACROSS THE REGION. UNDER ANY TSRA MVFR CEILINGS AND BRIEF IFR VISIBILITIES WILL BE POSSIBLE. SUNDAY THROUGH MONDAY...GENERALLY VFR. && .MARINE... SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED TODAY WITH SEAS 2-3 FEET OR LESS AND SOUTHEAST WINDS 5 TO 10 KNOTS. OUTLOOK... FRIDAY...CONDITIONS EXPECTED TO STAY BELOW SMALL CRAFT ADVISORY CRITERIA. SATURDAY...OCCASIONAL GUSTS NEAR 25 KT AND WAVE HEIGHTS APPROACHING 5 FT ARE POSSIBLE ESPECIALLY SATURDAY AFTERNOON THROUGH SATURDAY NIGHT. SUNDAY AND MONDAY...WAVE HEIGHTS AND WINDS SLOWLY FALLING BELOW SMALL CRAFT ADVISORY CRITERIA SUNDAY MORNING AND SHOULD REMAIN BELOW CRITERIA THROUGH MONDAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...JOHNSON NEAR TERM...ROBERTSON SHORT TERM...ROBERTSON LONG TERM...JOHNSON AVIATION...JOHNSON/ROBERTSON MARINE...JOHNSON/ROBERTSON
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1044 PM EDT FRI AUG 22 2014 .SYNOPSIS... A BACK DOOR COLD FRONT WILL MOVE INTO AND THROUGH THE NORTHERN AND CENTRAL MIDLANDS SATURDAY...AND THEN SHIFT TOWARDS THE CSRA SUNDAY. THIS WILL LEAD TO A CHANCE OF THUNDERSTORMS ALONG AND AHEAD OF THE FRONT...WITH TEMPERATURES RETURNING TO MORE NORMAL LEVELS BEHIND IT. THE FRONT WILL LINGER SOUTH OF THE CSRA EARLY TO MID NEXT WEEK...LEADING TO GENERALLY FAIR WEATHER WITH NEAR NORMAL TEMPERATURES. && .NEAR TERM /UNTIL 7 AM SATURDAY MORNING/... WV LOOP SHOWS WEAK S/W MOVING SOUTHEASTWARD TOWARD THE NRN CWA/PEE DEE REGION. MODELS ALSO SHOW THIS S/W MOVING SOUTH/SOUTHEAST OVERNIGHT. 88D REGIONAL COMPOSITE SHOWS A CLUSTER OF SHRA/TSRA JUST NORTH OF CLT. HRRR INDICATES THAT SOME OF THIS ACTIVITY COULD SLIP INTO THE NRN MIDLANDS/PEE DEE OVER THE NEXT FEW HOURS. HAVE INCREASED POPS SLIGHTLY ACROSS LANCASTER...CHESTERFIELD...NRN KERSHAW AND NERN LEE COUNTY. OVERNIGHT LOWS IN THE LOW/MID 70S LOOK ON TRACK. OTHERWISE...SURFACE LOW PRESSURE ALONG THE VA COAST IS FORECAST TO MOVE SOUTHWARD OVERNIGHT INTO EASTERN NC. THIS WILL ALLOW A BACKDOOR COLD FRONT TO APPROACH THE NORTHERN MIDLANDS/PEE DEE AROUND DAYBREAK SATURDAY. KEPT OVERNIGHT LOWS NEAR CONSENSUS IN THE LOWER AND MIDDLE 70S. && .SHORT TERM /7 AM SATURDAY MORNING THROUGH SUNDAY/... MAIN ISSUE FOR SATURDAY AND INTO SUNDAY IS TIMING OF APPROACHING BACK DOOR FRONT. THINK PRE-FRONTAL TROUGH SETS UP ACROSS SOUTHERN CWA SATURDAY WITH FRONT IN EASTERN NORTH CAROLINA SHIFTING SOUTHWEST DURING SATURDAY EVENING. MOS POP GUIDANCE LOW BUT SREF AND MODEL QPF SUGGEST SCATTERED SHOWERS AND THUNDERSTORMS AHEAD AND ALONG FRONT AS AIR MASS MODERATELY UNSTABLE AND MOISTURE INCREASING...PRECIPITABLE WATER MAY RISE TO AROUND 2 INCHES. WARM MAX TEMPS STILL POSSIBLE SAT AHEAD OF THE FRONT...WITH WARMEST TEMPS FAVORING THE CSRA WHERE TEMPS COULD REACH 100 AGAIN. WITH NAM BEING SLIGHTLY FASTER THAN GFS WITH THE BACK DOOR FRONT...THE NAM MOS IS SLIGHTLY COOLER THAN THE GFS MOS FOR SAT MAX TEMP...ESPECIALLY NORTH AND CENTRAL. EVEN IF TEMPS NEAR 100 REACHED AGAIN SAT...GUIDANCE STILL SUGGESTS DEWPOINTS LOW ENOUGH TO PRECLUDE HEAT INDEX VALUES FROM REACHING OUR HEAT ADVISORY CRITERIA OF 110F. FRONT EXPECTED TO SHIFT SW THRU THE FA SAT NIGHT THRU SUN NIGHT. EXPECT CHANCE POPS NEAR AND JUST AHEAD OF THE FRONT...WITH COOLING TEMPS ALONG AND NORTH OF IT. SO...POPS SUN AFTERNOON FAVORING THE CSRA WHERE INSTABILITY/LOW LEVEL CONVERGENCE STRONGER. HIGH TEMPS SUNDAY SHOULD BE NOTICEABLY LESS BEHIND THE FRONT. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... MODELS IN GOOD AGREEMENT WITH MOVING THE FRONT SOUTH OF THE SAVANNAH RIVER WITH UPPER LEVEL RIDGE BUILDING IN FOR THE WEEK. WITH COOLER DRY AIR SETTLING IN WILL BRING SLIGHTLY BELOW NORMAL TEMPS. EXPECT MAX TEMPS 85 TO 90 EARLY TO MID WEEK RISING BACK INTO THE LOWER 90S LATER IN THE WEEK. OVERNIGHT MINS WILL BE 65 TO 70 RISING INTO THE LOWER 70S LATER IN THE WEEK. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS EXPECTED THROUGH THE PERIOD. MAINLY SCATTERED MID AND UPPER LEVEL CLOUDINESS THROUGH THE PERIOD. DRY FORECAST EXPECTED OVERNIGHT. FRONTAL BOUNDARY REMAINS NORTH OF THE AREA. WINDS LIGHT AND VARIABLE OVERNIGHT...BECOMING NORTHERLY THROUGH THE DAY SATURDAY. FRONT NORTH OF THE AREA WILL SAG A LITTLE FURTHER SOUTH ON SATURDAY...BUT WILL REMAIN NORTH OF ALL TAF SITES. ISOLATED TO SCATTERED CONVECTION MAY BE POSSIBLE DURING THE AFTERNOON SATURDAY...BUT DUE TO LIMITED COVERAGE WILL NOT INCLUDE IN THE TAFS AT THIS TIME. BEST CHANCE WILL BE CLOSER TO THE MIDLANDS TAF SITES SATURDAY AFTERNOON. EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG SUNDAY AND MONDAY. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS SATURDAY EVENING AND SUNDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ 77
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
735 PM EDT FRI AUG 22 2014 .SYNOPSIS... A BACK DOOR COLD FRONT WILL MOVE INTO AND THROUGH THE NORTHERN AND CENTRAL MIDLANDS SATURDAY...AND THEN SHIFT TOWARDS THE CSRA SUNDAY. THIS WILL LEAD TO A CHANCE OF THUNDERSTORMS ALONG AND AHEAD OF THE FRONT...WITH TEMPERATURES RETURNING TO MORE NORMAL LEVELS BEHIND IT. THE FRONT WILL LINGER SOUTH OF THE CSRA EARLY TO MID NEXT WEEK...LEADING TO GENERALLY FAIR WEATHER WITH NEAR NORMAL TEMPERATURES. && .NEAR TERM /TONIGHT/... ATMOSPHERE REMAINS CAPPED ACROSS THE MIDLANDS AND AIRMASS IS DRIER WITH DEWPOINT TEMPERATURES IN THE UPPER 50S TO MIDDLE 60S. CWA SHOULD REMAIN DRY TONIGHT...AND THIS FORECAST AGREES WELL WITH HRRR AS IT SHOWS ANY ACTIVITY REMAINING NORTH OF THE CWA. SURFACE LOW PRESSURE ALONG THE VA COAST IS FORECAST TO MOVE SOUTHWARD OVERNIGHT INTO EASTERN NC. THIS WILL ALLOW A BACKDOOR COLD FRONT TO APPROACH THE NORTHERN MIDLANDS AROUND DAYBREAK SATURDAY. KEPT OVERNIGHT LOWS NEAR CONSENSUS IN THE LOWER AND MIDDLE 70S. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... MAIN ISSUE FOR SATURDAY AND INTO SUNDAY IS TIMING OF APPROACHING BACK DOOR FRONT. THINK PRE-FRONTAL TROUGH SETS UP ACROSS SOUTHERN CWA SATURDAY WITH FRONT IN EASTERN NORTH CAROLINA SHIFTING SOUTHWEST DURING SATURDAY EVENING. MOS POP GUIDANCE LOW BUT SREF AND MODEL QPF SUGGEST SCATTERED SHOWERS AND THUNDERSTORMS AHEAD AND ALONG FRONT AS AIR MASS MODERATELY UNSTABLE AND MOISTURE INCREASING...PRECIPITABLE WATER MAY RISE TO AROUND 2 INCHES. WARM MAX TEMPS STILL POSSIBLE SAT AHEAD OF THE FRONT...WITH WARMEST TEMPS FAVORING THE CSRA WHERE TEMPS COULD REACH 100 AGAIN. WITH NAM BEING SLIGHTLY FASTER THAN GFS WITH THE BACK DOOR FRONT...THE NAM MOS IS SLIGHTLY COOLER THAN THE GFS MOS FOR SAT MAX TEMP...ESPECIALLY NORTH AND CENTRAL. EVEN IF TEMPS NEAR 100 REACHED AGAIN SAT...GUIDANCE STILL SUGGESTS DEWPOINTS LOW ENOUGH TO PRECLUDE HEAT INDEX VALUES FROM REACHING OUR HEAT ADVISORY CRITERIA OF 110F. FRONT EXPECTED TO SHIFT SW THRU THE FA SAT NIGHT THRU SUN NIGHT. EXPECT CHANCE POPS NEAR AND JUST AHEAD OF THE FRONT...WITH COOLING TEMPS ALONG AND NORTH OF IT. SO...POPS SUN AFTERNOON FAVORING THE CSRA WHERE INSTABILITY/LOW LEVEL CONVERGENCE STRONGER. HIGH TEMPS SUNDAY SHOULD BE NOTICEABLY LESS BEHIND THE FRONT. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... MODELS IN GOOD AGREEMENT WITH MOVING THE FRONT SOUTH OF THE SAVANNAH RIVER WITH UPPER LEVEL RIDGE BUILDING IN FOR THE WEEK. WITH COOLER DRY AIR SETTLING IN WILL BRING SLIGHTLY BELOW NORMAL TEMPS. EXPECT MAX TEMPS 85 TO 90 EARLY TO MID WEEK RISING BACK INTO THE LOWER 90S LATER IN THE WEEK. OVERNIGHT MINS WILL BE 65 TO 70 RISING INTO THE LOWER 70S LATER IN THE WEEK. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS EXPECTED THROUGH THE PERIOD. MAINLY SCATTERED MID AND UPPER LEVEL CLOUDINESS THROUGH THE PERIOD. DRY FORECAST EXPECTED OVERNIGHT. FRONTAL BOUNDARY REMAINS NORTH OF THE AREA. WINDS LIGHT AND VARIABLE OVERNIGHT...BECOMING NORTHERLY THROUGH THE DAY SATURDAY. FRONT NORTH OF THE AREA WILL SAG A LITTLE FURTHER SOUTH ON SATURDAY...BUT WILL REMAIN NORTH OF ALL TAF SITES. ISOLATED TO SCATTERED CONVECTION MAY BE POSSIBLE DURING THE AFTERNOON SATURDAY...BUT DUE TO LIMITED COVERAGE WILL NOT INCLUDE IN THE TAFS AT THIS TIME. BEST CHANCE WILL BE CLOSER TO THE MIDLANDS TAF SITES SATURDAY AFTERNOON. EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG SUNDAY AND MONDAY. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS SATURDAY EVENING AND SUNDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
535 PM EDT THU AUG 21 2014 .SYNOPSIS... A BUILDING UPPER RIDGE WILL LEAD TO CONTINUED HOT CONDITIONS FRIDAY. A BACK DOOR COLD FRONT WILL MOVE SW INTO THE NORTHERN AND CENTRAL MIDLANDS SATURDAY AFTERNOON...AND SHIFT TOWARDS THE CSRA SUNDAY. THIS WILL LEAD TO A CHANCE OF THUNDERSTORMS ALONG AND AHEAD OF THE FRONT...WITH TEMPERATURES RETURNING TO MORE NORMAL LEVELS BEHIND IT. THE FRONT WILL SHIFT TO OUR SOUTH EARLY TO MID NEXT WEEK...LEADING TO GENERALLY FAIR WEATHER WITH NEAR NORMAL TEMPERATURES. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... UPPER RIDGE AND SURFACE HIGH PRESSURE CENTERED OVER THE LOWER MISSISSIPPI VALLEY/GULF COAST BUILDING INTO THE REGION. LATE AFTERNOON VISIBLE SATELLITE CONTINUES TO INDICATE SUBSIDENCE ACROSS THE AREA WITH VERY FEW CLOUDS. WEAK INSTABILITY AND WARM TEMPERATURES ALOFT. LFC REMAINS HIGH...CONVECTIVE TEMPS HIGH AND TRIGGER LACKING. CURRENT RAP AND NAM MODEL STILL INDICATING A WEAKENING SHORT WAVE CROSS THE AREA AFTER 22Z. 88D REGIONAL COMPOSITE SHOWS A FEW SHOWERS/THUNDERSTORMS ACROSS THE UPSTATE AND GEORGIA...BUT THE MIDLANDS AND CSRA REMAIN PRECIP FREE. HOWEVER WITH S/W...AN ISOLATED EARLY EVENING THUNDERSTORM IS STILL POSSIBLE WITH HE BEST CHANCES ALONG AND WEST OF THE SAVANNAH RIVER INTO CENTRAL GEORGIA. HAVE KEPT POPS LESS THAN 15 PERCENT WITH NO MENTION IN THE FORECAST. EXPECT SOME DEBRIS CLOUDS TONIGHT FROM UPSTREAM CONVECTION. OVERNIGHT LOWS IN THE LOW TO MID 70S ARE FORECAST. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/... LITTLE CHANGE FRIDAY. UPPER RIDGE WILL REMAIN CENTERED JUST TO OUR WEST...WITH SURFACE TROUGH ACROSS THE COASTAL CAROLINAS. THIS AND A LOW LEVEL DOWNSLOPE FLOW WILL LEAD TO CONTINUED HOT MAX TEMPS. MODELS CONTINUE TO INDICATE MAX TEMPS NEAR 100 DEGREES AGAIN MOST AREAS...AND ALSO CONTINUES TO INDICATES DEW POINTS MIXING DOWN INTO THE 60S ACROSS MOST OF OUR FA TO NEAR 70 SE FA...KEEPING HEAT INDICES BELOW OUR HEAT ADVISORY CRITERIA OF 110F. ONLY ISOLATED TO SLIGHT CHANCE DIRUNAL TSTMS AT BEST DUE TO BUILDING RIDGE ALOFT...AND FAIRLY DRY LOW LEVEL AIR LEADING TO HIGH LEVELS OF FREE CONVECTION/HIGH CONVECTIVE TEMPS. MAIN ISSUE FOR SATURDAY AND INTO SUNDAY IS TIMING OF APPROACHING BACK DOOR FRONT. LATEST NAM A LITTLE FASTER THAN GFS. GUIDANCE BLEND AND SHORT RANGE ENSEMBLE SUGGEST FRONT WITH ASSOCIATED BAND OF THUNDERSTORMS MOVING INTO THE NORTHERN AND CENTRAL FA SATURDAY AFTERNOON. CHANCE POPS SHOULD GENERALLY SUFFICE. WARM MAX TEMPS STILL POSSIBLE SAT AHEAD OF THE FRONT...WITH WARMEST TEMPS FAVORING THE CSRA WHERE TEMPS COULD REACH 100 AGAIN. WITH NAM BEING SLIGHTLY FASTER THAN GFS WITH THE BACK DOOR FRONT...THE NAM MOS IS SLIGHTLY COOLER THAN THE GFS MOS FOR SAT MAX TEMP...ESPECIALLY NORTH AND CENTRAL. EVEN IF TEMPS NEAR 100 REACHED AGAIN SAT...GUIDANCE STILL SUGGESTS DEWPOINTS LOW ENOUGH TO PRECLUDE HEAT INDEX VALUES FROM REACHING OUR HEAT ADVISORY CRITERIA OF 110F. FRONT EXPECTED TO SHIFT SW THRU THE FA SAT NT THRU SUN NT. EXPECT CHANCE POPS NEAR AND JUST AHEAD OF THE FRONT...WITH COOLING TEMPS ALONG AND NORTH OF IT. SO...POPS SUN AFTN FAVORING THE CSRA. HIGH TEMPS SUNDAY SHOULD BE NOTICEABLY LESS BEHIND THE FRONT. && .LONG TERM /MONDAY THROUGH THURSDAY/... FRONT TO PUSH TO OUR SOUTH EARLY TO MID NEXT WEEK WITH SURFACE HIGH PRESSURE BUILDING DOWN THE EASTERN SEABOARD...WITH UPPER RIDGE ALOFT. SLIGHTLY COOLER AND DRIER AIR BEHIND THE FRONT ALONG WITH RIDGE ALOFT WILL REDUCE CONVECTIVE CHANCES...TO SLIGHT CHANCE AT BEST. TEMPS EXPECTED TO BE GENERALLY NEAR NORMAL. && .AVIATION /22Z THURSDAY THROUGH TUESDAY/... VFR CONDITIONS EXPECTED TO DOMINATE THE PERIOD. EXPECT A FEW DIURNAL CUMULUS THIS AFTERNOON...BUT SKIES WILL REMAIN NEARLY SUNNY. POTENTIAL FOR CONVECTION REMAINS TOO LOW TO INCLUDE IN TAFS. CUMULUS WILL DISSIPATE WITH SUNSET WITH CONVECTIVE DEBRIS CROSSING THE AREA TONIGHT...WHICH WILL AGAIN WORK TO PREVENT FOG DEVELOPMENT. GFS LAMP STILL INDICATING MVFR FOG AT AGS/OGB 06Z- 13Z. GIVEN EXPECTED DRY AIRMASS AND HIGH CLOUDS...WILL NOT INCLUDE IN FOG IN THE FORECAST. NORTHERLY WINDS AROUND 5 KNOTS THIS AFTERNOON DIMINISHING TO NEAR CALM TONIGHT. EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG SATURDAY THROUGH MONDAY. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ 77
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
214 PM EDT THU AUG 21 2014 .SYNOPSIS... A BUILDING UPPER RIDGE WILL LEAD TO CONTINUED HOT CONDITIONS FRIDAY. A BACK DOOR COLD FRONT WILL MOVE SW INTO THE NORTHERN AND CENTRAL MIDLANDS SATURDAY AFTERNOON...AND SHIFT TOWARDS THE CSRA SUNDAY. THIS WILL LEAD TO A CHANCE OF THUNDERSTORMS ALONG AND AHEAD OF THE FRONT...WITH TEMPERATURES RETURNING TO MORE NORMAL LEVELS BEHIND IT. THE FRONT WILL SHIFT TO OUR SOUTH EARLY TO MID NEXT WEEK...LEADING TO GENERALLY FAIR WEATHER WITH NEAR NORMAL TEMPERATURES. && .NEAR TERM /THROUGH TONIGHT/... UPPER RIDGE AND SURFACE HIGH PRESSURE CENTERED OVER THE LOWER MISSISSIPPI VALLEY/GULF COAST BUILDING INTO THE REGION. VISIBLE SATELLITE INDICATING SUBSIDENCE ACROSS THE AREA WITH PRACTICALLY NO CLOUDS. 850MB WARM ADVECTION/DOWNSLOPE FLOW WILL RESULT IN TEMPERATURES APPROACHING 100 DEGREES. WEAK INSTABILITY AND WARM TEMPERATURES ALOFT. LFC REMAINS HIGH...CONVECTIVE TEMPS HIGH AND TRIGGER LACKING. CURRENT RAP AND NAM MODEL STILL INDICATING A WEAKENING SHORT WAVE CROSS THE AREA AFTER 22Z. SO CANNOT RULE OUT ISOLATED LATE AFTERNOON/EARLY EVENING THUNDERSTORM. HAVE LOWERED POPS TO LESS THAN 15 PERCENT. DEW POINTS MIXING OUT INTO THE LOW/MID 60S THIS AFTERNOON SO HEAT INDEX LIKELY MAXING OUT AROUND 102 DEGREES. EXPECT DEBRIS CLOUDS TONIGHT FROM UPSTREAM CONVECTION. OVERNIGHT LOWS IN THE LOW TO MID 70S ARE FORECAST. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... LITTLE CHANGE FRIDAY. UPPER RIDGE WILL REMAIN CENTERED JUST TO OUR WEST...WITH SURFACE TROUGH ACROSS THE COASTAL CAROLINAS. THIS AND A LOW LEVEL DOWNSLOPE FLOW WILL LEAD TO CONTINUED HOT MAX TEMPS. MODELS CONTINUE TO INDICATE MAX TEMPS NEAR 100 DEGREES AGAIN MOST AREAS...AND ALSO CONTINUES TO INDICATES DEW POINTS MIXING DOWN INTO THE 60S ACROSS MOST OF OUR FA TO NEAR 70 SE FA...KEEPING HEAT INDICES BELOW OUR HEAT ADVISORY CRITERIA OF 110F. ONLY ISOLATED TO SLIGHT CHANCE DIRUNAL TSTMS AT BEST DUE TO BUILDING RIDGE ALOFT...AND FAIRLY DRY LOW LEVEL AIR LEADING TO HIGH LEVELS OF FREE CONVECTION/HIGH CONVECTIVE TEMPS. MAIN ISSUE FOR SATURDAY AND INTO SUNDAY IS TIMING OF APPROACHING BACK DOOR FRONT. LATEST NAM A LITTLE FASTER THAN GFS. GUIDANCE BLEND AND SHORT RANGE ENSEMBLE SUGGEST FRONT WITH ASSOCIATED BAND OF THUNDERSTORMS MOVING INTO THE NORTHERN AND CENTRAL FA SATURDAY AFTERNOON. CHANCE POPS SHOULD GENERALLY SUFFICE. WARM MAX TEMPS STILL POSSIBLE SAT AHEAD OF THE FRONT...WITH WARMEST TEMPS FAVOIRNG THE CSRA WHERE TEMPS COULD REACH 100 AGAIN. WITH NAM BEING SLIGHTLY FASTER THAN GFS WITH THE BACK DOOR FRONT...THE NAM MOS IS SLIGHTLY COOLER THAN THE GFS MOS FOR SAT MAX TEMP...ESPECIALLY NORTH AND CENTRAL. EVEN IF TEMPS NEAR 100 REACHED AGAIN SAT...GUIDANCE STILL SUGGESTS DEWPOINTS LOW ENOUGH TO PRECLUDE HEAT INDEX VALUES FROM REACHING OUR HEAT ADVIOSRY CRITERIA OF 110F. FRONT EXPECTED TO SHIFT SW THRU THE FA SAT NT THRU SUN NT. EXPECT CHANCE POPS NEAR AND JUST AHEAD OF THE FRONT...WITH COOLING TEMPS ALONG AND NORTH OF IT. SO...POPS SUN AFTN FAVORING THE CSRA. HIGH TEMPS SUNDAY SHOULD BE NOTICEABLY LESS BEHIND THE FRONT. && .LONG TERM /MONDAY THROUGH THURSDAY/... FRONT TO PUSH TO OUR SOUTH EARLY TO MID NEXT WEEK WITH SURFACE HIGH PRESSURE BUILDING DOWN THE EASTERN SEABOARD...WITH UPPER RIDGE ALOFT. SLIGHTLY COOLER AND DRIER AIR BEHIND THE FRONT ALONG WITH RIDGE ALOFT WILL REDUCE CONVECTIVE CHANCES...TO SLIGHT CHANCE AT BEST. TEMPS EXPECTED TO BE GENERALLY NEAR NORMAL. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... VFR CONDITIONS EXPECTED TO DOMINATE THE PERIOD. EXPECT SOME DIURNAL CUMULUS TO DEVELOP THIS AFTERNOON. POTENTIAL FOR CONVECTION REMAINS TOO LOW TO INCLUDE IN TAFS. CUMULUS WILL DISSIPATE WITH SUNSET WITH CONVECTIVE DEBRIS CROSSING THE AREA TONIGHT...WHICH WILL AGAIN WORK TO PREVENT FOG DEVELOPMENT. GFS LAMP STILL INDICATING MVFR FOG AT AGS/OGB 06Z-13Z. GIVEN EXPECTED DRY AIRMASS AND HIGH CLOUDS...WILL NOT INCLUDE IN FOG IN THE FORECAST. NORTHERLY WINDS AROUND 5 KNOTS THIS AFTERNOON DIMINISHING TO NEAR CALM TONIGHT. EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG SATURDAY THROUGH MONDAY. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
211 AM EDT THU AUG 21 2014 .SYNOPSIS... DRIER AIR AND A BUILDING UPPER RIDGE JUST TO OUR WEST WILL REDUCE THUNDERSTORM CHANCES THROUGH FRIDAY...AND LEAD TO HOTTER HIGH TEMPERATURES. AN APPROACHING COLD FRONT AND INCREASING MOISTURE WILL INCREASE THE THUNDERSTORM CHANCE OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... SCATTERED CONVECTION HAS ENDED ACROSS THE AREA THIS EVENING. STILL SOME ACTIVITY WELL UPSTREAM OVER ERN TN AND NRN GA BUT AT THIS TIME EXPECT THOSE STORMS TO STAY EITHER WELL WEST OF THE FORECAST AREA OR DISSIPATE BEFORE REACHING OUR AREA GIVEN THE LATEST HRRR CYCLE. NOCTURNAL COOLING WITH DRY AIR ALOFT AND LIGHT WIND SHOULD HELP SUPPORT AREAS OF FOG TOWARD SUNRISE. OVERNIGHT LOWS IN THE IN THE LOWER AND MIDDLE 70S STILL LOOK REASONABLE. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... UPPER RIDGE WILL BUILD JUST TO OUR WEST. THIS AND A LOW LEVEL DOWNSLOPE FLOW WILL LEAD TO WARMING TEMPS. MODELS CONTINUE TO INDICATE MAX TEMPS NEAR 100 DEGREES MOST AREAS...AND CONTINUE TO INDICATES DEW POINTS MIXING DOWN INTO THE MID TO UPPER 60S ACROSS THE NORTHERN AND WESTERN COUNTIES TO NEAR 70 OR LOWER 70S ACROSS THE SOUTHEAST MIDLANDS. THIS KEEPS HEAT INDICES JUST BELOW OUR HEAT ADVISORY CRITERIA OF 110F. ONLY SLIGHT CHANCE OF SHOWERS/TSTMS EXPECTED DUE TO BUILDING RIDGE ALOFT...AND FAIRLY DRY LOW LEVEL AIR LEADING TO AND HIGH LEVELS OF FREE CONVECTION/HIGH CONVECTIVE TEMPS. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... UPPER RIDGE TO OUR WEST WITH UPPER TROUGH AND CLOSED LOW TO OUR NE...PROVIDING A NW FLOW ALOFT FOR OUR FA. SOME TIMING UNCERTAINTIES WITH A BACK DOOR FRONT. MODELS TRENDING A LITTLE SLOWER WITH IT OF LATE...WITH POSSIBILITY THAT IT MAY NOT MAKE IT TO OUR FA UNTIL SATURDAY AFTERNOON OR EVENING...SLOWLY PUSHING SOUTH THROUGH SUNDAY. INCREASING POPS/THUNDER CHANCE ALONG AND SOUTH OF THE BOUNDARY...WITH COOLER TEMPS NORTH OF IT. FRONT TO PUSH TO OUR SOUTH EARLY NEXT WEEK...WITH SURFACE AND UPPER RIDGE OVER THE EASTERN SEABOARD. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... EXPECT VFR CONDITIONS TO DOMINATE THE PERIOD...WITH EARLY MORNING MVFR CONDITIONS AT AGS/OGB. CIRRUS FROM UPSTREAM CONVECTION CONTINUES TO BLANKET THE AREA AND WILL WORK TO LIMIT FOG DEVELOPMENT. WITH THE CLOUDS EXPECTED THROUGH MUCH OF THE NIGHT HAVE DECREASED THE FOG THREAT AT CAE/CUB/DNL TO A TEMPO GROUP WHILE MAINTAINING MVFR FOG AT AGS/OGB. FOG WHICH DEVELOPS WILL QUICKLY ERODE WITH SUNRISE WITH THE REMAINDER OF THE PERIOD VFR. CHANCES OF DIURNAL CONVECTION REMAIN TOO LOW TO INCLUDE IN TAFS. WINDS THROUGH THE PERIOD WILL BE WESTERLY AT 5 KNOTS OR LESS. EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG THROUGH THE PERIOD. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 1104 PM CDT Fri Aug 22 2014 .UPDATE... ISSUED AT 845 PM CDT FRI AUG 22 2014 Latest surface analysis indicating what`s left of an old outflow boundary from today`s convection located over parts of southeast Illinois this evening with some widely scattered showers along it. Further to the north, the synoptic frontal boundary was located over far southern Wisconsin with a weak cold front noted across central Iowa. Mid to upper 70 dew points were widespread from Iowa and Illinois south into the northern half of Missouri. 00z ILX sounding showing plenty of Cape for a parcel able to get above 800 mb later tonight with current Most Unstable Capes ranging from 2500-3500 J/kg. ILX Local objective analysis indicating a cap in place across the north and east, probably the result of the convection persisting into the early afternoon. Precipitable water values off the wall on the SPC mesoanalysis page with 2.2-2.3 inches analyzed this past hour from west central Illinois southeast into far southern Illinois. 0-6km shear values of only 15 to 20 kts compared to last night when we saw 30-35 kts. Now the main forecast concern, where and when convection breaks out again overnight. Models were definitely weaker with the low level jet with more of a split in the jet indicated with one area splitting off north into the central Plains with a much weaker jetlet forecast into southwest Missouri. Models do show some weak 850 mb moisture convergence/theta-e advection later tonight over parts of northeast Missouri into southeast Iowa. Latest HRRR model trending more towards what we saw with the 18z Nam-Wrf solution with the focus more with the aforementioned weak outflow boundary across south central and southeast Illinois later tonight. Any storms that do organize will bring the threat of heavy rain due to the weaker wind fields aloft and gusty winds, along with quite a lightning show. Storms that have been progressing slowly across parts of central Iowa late this afternoon and early this evening not showing a great deal of organization at this point as they were located under the building 500 mb ridge. Have made some minor adjustments to the grids to reflect the current trends this evening and will be sending out an updated ZFP to freshen up the wording for the overnight hours. Overall though, no significant changes made to the overnight convection threat across our area. && .SHORT TERM...(This evening through Saturday) ISSUED AT 256 PM CDT FRI AUG 22 2014 Main short-term concern is potential convective re-development tonight. As has been the case for the past few days, forecast models once again are having difficulty predicting the exact placement and track of nocturnal storm complex. Synoptic boundary remains draped well to the north from far northern Iowa to southern Lake Michigan: however, convection from earlier today was tied to an outflow boundary that dropped further southward into central Illinois. Think storms will develop along mesoscale boundaries later this evening as the low-level jet strengthens into the region. Radar trends are already showing scattered thunderstorms forming across central Iowa and these should develop/spread eastward into west-central Illinois later this evening. Mean flow would take the convection E/SE across the area overnight into Saturday morning. Based on radar trends and latest model data, have gone with high chance PoPs along/northeast of I-74, tapering down to just slight chances across the far S/SE CWA tonight. Given the very moist airmass as characterized by precipitable water values of over 2 inches, locally heavy rainfall will be possible late tonight into early Saturday morning. Convection will tend to move further eastward into Indiana and diminish toward midday Saturday, resulting in a mainly dry afternoon. Given increasing amounts of sunshine, high temperatures on Saturday will reach the upper 80s and lower 90s. These readings, combined with dewpoints in the middle 70s, will produce heat index values of 100 to 105F. Have therefore continued the current Heat Advisory with no areal changes. && .LONG TERM...(Saturday night through Friday) ISSUED AT 256 PM CDT FRI AUG 22 2014 Will continue the heat advisory for areas from Lincoln ssw through Monday afternoon for heat indices peaking from 100-107F and highest on Sunday and Monday afternoon over sw counties where several areas will be near 105F heat index. Highs in the low to mid 90s and dewpoints in the 70s to support these heat indices. Will need to keep alert to the possibility of expanding the heat advisory a bit further nne Sunday through Tuesday if heat indices reach closer to 105F. Strong upper level ridge building over the mid ms river valley Sun/Mon to cap atmosphere over central/sw IL and generally went dry with just ne IL have isolated convection. Upper level ridge to slowly break down during middle of next week allowing a frontal boundary to press se into IL. ECMWF is slower with front on Wed night and Thu. GFS is Wed afternoon into Wed night while GEM has front passing se into the IL river valley by overnight Wed night. With models trending slower past few days, favor the slower ECMWF and GEM models with frontal boundary pushing through central IL Wed night and southeast IL Thu. Have 20-30% chances of showers and thunderstorms returning Tue and Tue night, with best chances Wed/Thu. Still very warm and humid Wed with highs in the mid to upper 80s while southeast IL near 90F where afternoon heat indices peak in upper 90s to near 100F. More cooler air filters in on Thu with highs around 80F central IL and lower 80s southeast IL. Dewpoints slip into the mid to upper 50s during Thu night. Have dry conditions returning by Friday with more comfortable temperature and humidity levels, with highs next Friday in the upper 70s central IL and near 80F southeast IL with dewpoints in the upper 50s and lower 60s. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 1100 PM CDT FRI AUG 22 2014 Main forecast challenge remains timing and coverage of TSRA across our TAF locations overnight. Little overall change in thinking from previous set of TAFs with convection coverage still very much in doubt late this evening as the low level jet was positioned further to our west than the previous nights and other than a weak outflow boundary over southeast Illinois, the closest frontal boundary to us was located over far southern Wisconsin. Unless we see a dramatic increase in coverage of showers and storms over the next hour, will resort back to mentioning VCTS during the early morning hours into Saturday morning. Short term models not helping much as they have been coming up with a different solution with each run. Another concern will be with the potential for fog development in the 08z-13z time frame. Temp-dew point spreads, except for KPIA, were down to 3 degrees or less over the past hour and with copious amounts of moisture in the low levels, thanks in part to the moderate to locally heavy rain that fell across the area today, will introduce some MVFR vsbys at most sites. Whatever fog we see in the morning should lift by 13-14z with any lingering shower activity pulling out of the area by late morning with mainly VFR conditions expected for the rest of the forecast period. Surface winds will be light easterly at less than 5 kts tonight and then turn more into a southeast direction at less than 10 kts on Saturday. && .ILX WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY until 7 PM CDT Monday FOR ILZ042-047>054-056- 061>063-066>068-071>073. && $$ UPDATE...SMITH SHORT TERM...BARNES LONG TERM...07 AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1001 PM CDT FRI AUG 22 2014 .DISCUSSION... 259 PM CDT WE ARE LOOKING AT AN EXTENDED PERIOD OF MUGGY CONDITIONS OVER THE COMING WEEK WITH OFF AND ON CHANCES FOR SHOWERS AND THUNDERSTORMS. FORECAST FOCUS WAS TRYING TO PIN DOWN BETTER TIME FRAMES FOR THUNDERSTORM ACTIVITY. THIS IS COMPLICATED BY TRACKING VERY SUBTLE WAVES THAT MAKE ALL THE DIFFERENCE IN WHEN AND WHERE ADDITIONAL HEAVY RAIN WILL FALL. THE OVERALL PATTERN IS CHARACTERIZED BY A VERY BROAD UPPER RIDGE ACROSS THE MIDWEST WITH THE CENTER OF HIGH PRESSURE OVER THE ALABAMA/MISSISSIPPI WITH TROUGHING OFF THE EAST COAST...AN UPPER LEVEL TROUGH OVER THE PACIFIC NORTHWEST WITH A SHORTWAVE TROUGH FEEDING INTO THE BACK SIDE OF THE RIDGE IN ARIZONA. CLOSER TO HOME...WE ARE SOMEWHAT IN THE RING OF FIRE ON THE NORTH SIDE OF THE UPPER RIDGE AXIS WHERE SMALLER SCALE PERTURBATIONS CONTINUED TO ROTATE THROUGH THE AREA. THE UPPER LEVEL FLOW IS WEAK...AND WITH THE PATTERN AMPLIFIED...THE PATTERN DOES NOT LOOK TO CHANGE MUCH SOON. MEANWHILE...THE LOWER LEVEL BAROCLINIC ZONE REMAINS DRAPED JUST TO THE SOUTH OF OUR CWA THIS AFTERNOON. THERE IS A SURFACE BOUNDARY POSITIONED ALONG THE NORTHERN TIER OF OUR AREA...BUT THE SURFACE PATTERN IS A BIT MORE MUDDLED. WIDESPREAD DEWPOINTS IN THE 70S SUMS THINGS UP PRETTY WELL. IN THE NEAR TERM...CONVECTION FROM EARLIER HAS PUSHED SOUTH HAS CONTINUED TO WEAKEN AND PUSH SOUTHWEST AS LOW LEVEL FLOW IS TURNING NORTHWESTERLY...PUSHING BETTER MOISTURE TRANSPORT AND LIFT INTO THE LOW LEVEL BAROCLINIC ZONE TO THE SOUTH OF OUR CWA. WE CONTINUE TO WATCH SMALLER SCALE WAVES IN IOWA THAT WILL TRAVERSE THE RIDGE AS MOISTURE CONTINUES TO FEED FROM THE GULF INTO THE CENTER OF THE COUNTRY AND TOWARDS THE AREA. SOME HIGH RESOLUTION GUIDANCE IS HINTING AT SOME CONVECTION ALONG A LAKE BREEZE THIS AFTERNOON. THIS COULD BE AN AREA OF FOCUS AS A WEAK WAVE IN IOWA APPROACHES. IF ANYTHING FORMS...IT WOULD BE ISOLATED. CONFIDENCE ON THIS HAPPENING IS LOW AS ONLY A HANDFUL OF GUIDANCE MEMBERS ARE SHOWING THIS SOLUTION AND FEEL THAT IT WOULD ONLY BE ALONG SUBTLE CONVERGENCE BOUNDARIES. MUCH OF THE LARGER SCALE MODELS KEEP ANY PRECIPITATION WITH THIS WAVE ALONG OUR SOUTH AND WESTERN TIER OF COUNTIES WHERE WE KEEP THE HIGHEST POPS. EVEN THIS IS IN QUESTION AS THE MAIN FORCING IS HAVING A HARD TIME GETTING OUT OF IOWA WHERE MORE ORGANIZED THUNDERSTORM ACTIVITY IS ONGOING...BUT IT IS THESE AREAS THERE IS SOME 925 MB FLOW STILL INTO THE LOWER LEVEL BAROCLINIC ZONE THAT MAY AID IN SOME ENHANCEMENT TONIGHT. AREAS IN AN AROUND LIVINGSTON COUNTY HAD SOME PRETTY SIGNIFICANT RAINFALL..SO THIS WOULD BE AN AREA TO WATCH IF WE GET SOME ADDITIONAL DEVELOPMENT THIS EVENING AS THE GFS/EC SUGGEST. IF STUFF GETS GOING IT MAY LINGER INTO THE MORNING HOURS. ADMITTEDLY THE EVOLUTION OVER THE NEXT 12-18 HOURS IS LOWER THAN I WOULD LIKE. MODELS CONTINUE TO DIFFER WITH THE HANDLING OF THINGS ON SATURDAY AS WELL BUT STILL GENERALLY AGREE WITH THE BEST CHANCES SOUTH AND WEST OF THE MAIN METROPOLITAN AREA. FEEL LIKE THERE WILL BE MANY DRY PERIODS BUT THAT THUNDER IS POSSIBLE AND THEREFORE SOME DEGREE OF CHANCE POPS FOR NOW...WITH AREAS CLOSER TO THE LAKE HAVING SMALLER CHANCES. CONFIDENCE IN THIS PERIOD IS LOW-MEDIUM. SATURDAY NIGHT INTO SUNDAY...THE UPPER LEVEL RIDGE AXIS WILL AMPLIFY CAUSING THE MAIN MOISTURE TRANSPORT AXIS TO REMAIN OFF TO THE WEST. THIS WILL LARGELY KEEP MUCH OF NORTHEAST ILLINOIS AND NORTHWEST INDIANA UNDER DRY BUT MUGGY CONDITIONS. CONCERNS ON SUNDAY AND MONDAY WILL BE MORE SO ON THE HOT AND HUMID CONDITIONS WHERE HEAT INDICES WILL BE WELL INTO THE 90S...APPROACHING 100 IN THE SW CWA. SHORTWAVE ENERGY CURRENTLY OVER ARIZONA WILL MERGE WITH THE LARGE SCALE TROUGH OVER THE NORTHWEST AS THE TROUGH MOVES EASTWARD. THE RIDGE LOOKS TO HOLD AND SHUNT MOST OF THE INITIAL SHORTWAVE ENERGY WITH THE TROUGH NORTH AND WEST...WHICH WOULD SUGGEST THAT MONDAY CHANCES OF SHOWERS AND STORMS REMAINS LOWER THAN THE REMAINDER OF THE WEEK...THOUGH WE MAY GET GRAZED WITH IT SO WILL CONTINUE THE LOWER POPS FOR MONDAY. ON TUESDAY THE TROUGH/MOISTURE TRANSPORT AXIS GETS CLOSER. IT APPEARS THAT WEDNESDAY AND WEDNESDAY NIGHT WILL BE THE DAY WHEN WE TRANSITION OUT OF THE CURRENT AIR MASS. A COLD FRONT ASSOCIATED WITH THE UPPER TROUGH WILL BRING THE BEST CHANCE FOR ORGANIZED SHOWERS AND THUNDERSTORMS. WHILE PRECIPITABLE WATER VALUES IN THE EXTENDED TEND TO DROP SOME...WE ARE STILL LOOKING AT 2-3 STANDARD DEVIATIONS ABOVE NORMAL WHICH MEANS ANY PERIOD OF THUNDERSTORM ACTIVITY WILL POSE A THREAT FOR HEAVY RAINFALL. ON WEDNESDAY WE WILL ALSO HAVE BETTER WIND SHEAR...SO ADDITIONAL HAZARDS EXISTS INCLUDING THE POTENTIAL FOR STRONG/SEVERE WINDS AND HAIL. COOLER AND DRIER CONDITIONS ARE ON TAP FOR THE LATTER HALF OF THE WEEK WITH THURSDAY BEING A BIT BREEZY BEFORE HIGH PRESSURE MOVES OVERHEAD. KMD KMD && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 03Z... * MVFR FOG AND IFR CIGS ARE EXPECTED AFTER MIDNIGHT. * SLIGHT CHANCE OF SHRA/TSRA THROUGH TOMORROW MORNING...INCREASING TO A CHANCE TOMORROW AFTERNOON. JEE //DISCUSSION...UPDATED 00Z... HIGH PRESSURE CENTERED OVER THE ST LOUIS AREA IS RESULTING IN A BUSY AND MESSY PATTERN OVER NORTHERN IL AND NW INDIANA. FIRST THE LAKE BREEZE HAS VIRTUALLY STALLED AND IS SPLITTING ORD. EXPECTING WINDS TO SLOWLY TURN E AT ORD BUT NOT EXPECTING THE LAKE BREEZE TO IMPACT ANY OTHER TERMINALS. WINDS WILL GRADUALLY TURN EAST OVERNIGHT AND REMAIN LIGHT AT 5 KT OR LESS. WITH THE VERY HUMID AIRMASS IN PLACE...EXPECTING FOG OVERNIGHT. IFR STRATUS IS ALSO EXPECTED SO THINKING THE LOW CIGS WILL LIMIT FOG DEVELOPMENT. RIGHT NOW HAVE ALL TERMINALS EXCEPT RFD AND GYY AT MVFR. THINKING GYY AND RFD HAVE THE BEST CHANCE AT GOING IFR OR LOWER TONIGHT. CIGS AND VSBY WILL RISE SATURDAY MORNING WITH LIGHT EAST WINDS CONTINUING. GUIDANCE FEATURES ANOTHER UPPER LEVEL DISTURBANCE MOVING THROUGH THE MIDWEST TOMORROW WHICH COULD PRODUCE SHOWERS AND STORMS ACROSS THE REGION. THE BEST CHANCE FOR TSRA IS TOMORROW AFTERNOON. HEAVY DOWNPOURS ARE POSSIBLE AS THE AIRMASS WILL STILL BE VERY HUMID. HAVE LIMITED CONFIDENCE IN TSRA COVERAGE AND TIMING SO KEPT TAFS DRY FOR NOW. RFD WILL HAVE THE BEST CHANCE FOR TSRA GIVEN ITS PROXIMITY TO THE UPPER LEVEL FEATURE. JEE //ORD AND MDW CONFIDENCE...UPDATED 03Z... * HIGH CONFIDENCE IN IFR CIGS AND MVFR VSBY DEVELOPING OVERNIGHT. MEDIUM CONFIDENCE IN HOW LONG CONDITIONS PERSIST SATURDAY MORNING. * HIGH CONFIDENCE IN ISOL TS STAYING OUT OF THE TERMINALS OVERNIGHT...MEDIUM-LOW CONFIDENCE IN TSRA COVERAGE AND TIMING TOMORROW AFTERNOON. * HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. JEE //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...SCHC TSRA IN THE AFTERNOON. MVFR CIGS/VSBY PSBL. MONDAY THROUGH WEDNESDAY...PERIODIC CHANCES FOR TSRA/SHRA WITH OCNL MVFR CIGS/VSBY. THURSDAY...SCHC SHRA. JEE && .MARINE... 246 PM CDT WINDS WILL REMAIN FAIRLY LIGHT AND FREQUENTLY CHANGING ACROSS THE LAKE OVER THE NEXT SEVERAL DAYS. A BROAD AREA OF LOW PRESSURE OVER THE PLAINS WILL CONSOLIDATE AND MOVE TO WESTERN ONTARIO SUNDAY. THIS WILL TURN WINDS SOUTHERLY AND INCREASE THEM SLIGHTLY TOWARD SUNDAY AFTERNOON INTO MONDAY. THE LOW WILL THEN TRACK NORTH OF THE LAKES AND PULL A FRONTAL BOUNDARY DOWN OVER LAKE MICHIGAN...LIKELY STALLING OUT OVER THE LAKE ALLOWING FOR VARIABLE WINDS TOWARD MIDWEEK. LENNING && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 851 PM CDT Fri Aug 22 2014 .UPDATE... ISSUED AT 845 PM CDT FRI AUG 22 2014 Latest surface analysis indicating what`s left of an old outflow boundary from today`s convection located over parts of southeast Illinois this evening with some widely scattered showers along it. Further to the north, the synoptic frontal boundary was located over far southern Wisconsin with a weak cold front noted across central Iowa. Mid to upper 70 dew points were widespread from Iowa and Illinois south into the northern half of Missouri. 00z ILX sounding showing plenty of Cape for a parcel able to get above 800 mb later tonight with current Most Unstable Capes ranging from 2500-3500 J/kg. ILX Local objective analysis indicating a cap in place across the north and east, probably the result of the convection persisting into the early afternoon. Precipitable water values off the wall on the SPC mesoanalysis page with 2.2-2.3 inches analyzed this past hour from west central Illinois southeast into far southern Illinois. 0-6km shear values of only 15 to 20 kts compared to last night when we saw 30-35 kts. Now the main forecast concern, where and when convection breaks out again overnight. Models were definitely weaker with the low level jet with more of a split in the jet indicated with one area splitting off north into the central Plains with a much weaker jetlet forecast into southwest Missouri. Models do show some weak 850 mb moisture convergence/theta-e advection later tonight over parts of northeast Missouri into southeast Iowa. Latest HRRR model trending more towards what we saw with the 18z Nam-Wrf solution with the focus more with the aforementioned weak outflow boundary across south central and southeast Illinois later tonight. Any storms that do organize will bring the threat of heavy rain due to the weaker wind fields aloft and gusty winds, along with quite a lightning show. Storms that have been progressing slowly across parts of central Iowa late this afternoon and early this evening not showing a great deal of organization at this point as they were located under the building 500 mb ridge. Have made some minor adjustments to the grids to reflect the current trends this evening and will be sending out an updated ZFP to freshen up the wording for the overnight hours. Overall though, no significant changes made to the overnight convection threat across our area. && .SHORT TERM...(This evening through Saturday) ISSUED AT 256 PM CDT FRI AUG 22 2014 Main short-term concern is potential convective re-development tonight. As has been the case for the past few days, forecast models once again are having difficulty predicting the exact placement and track of nocturnal storm complex. Synoptic boundary remains draped well to the north from far northern Iowa to southern Lake Michigan: however, convection from earlier today was tied to an outflow boundary that dropped further southward into central Illinois. Think storms will develop along mesoscale boundaries later this evening as the low-level jet strengthens into the region. Radar trends are already showing scattered thunderstorms forming across central Iowa and these should develop/spread eastward into west-central Illinois later this evening. Mean flow would take the convection E/SE across the area overnight into Saturday morning. Based on radar trends and latest model data, have gone with high chance PoPs along/northeast of I-74, tapering down to just slight chances across the far S/SE CWA tonight. Given the very moist airmass as characterized by precipitable water values of over 2 inches, locally heavy rainfall will be possible late tonight into early Saturday morning. Convection will tend to move further eastward into Indiana and diminish toward midday Saturday, resulting in a mainly dry afternoon. Given increasing amounts of sunshine, high temperatures on Saturday will reach the upper 80s and lower 90s. These readings, combined with dewpoints in the middle 70s, will produce heat index values of 100 to 105F. Have therefore continued the current Heat Advisory with no areal changes. && .LONG TERM...(Saturday night through Friday) ISSUED AT 256 PM CDT FRI AUG 22 2014 Will continue the heat advisory for areas from Lincoln ssw through Monday afternoon for heat indices peaking from 100-107F and highest on Sunday and Monday afternoon over sw counties where several areas will be near 105F heat index. Highs in the low to mid 90s and dewpoints in the 70s to support these heat indices. Will need to keep alert to the possibility of expanding the heat advisory a bit further nne Sunday through Tuesday if heat indices reach closer to 105F. Strong upper level ridge building over the mid ms river valley Sun/Mon to cap atmosphere over central/sw IL and generally went dry with just ne IL have isolated convection. Upper level ridge to slowly break down during middle of next week allowing a frontal boundary to press se into IL. ECMWF is slower with front on Wed night and Thu. GFS is Wed afternoon into Wed night while GEM has front passing se into the IL river valley by overnight Wed night. With models trending slower past few days, favor the slower ECMWF and GEM models with frontal boundary pushing through central IL Wed night and southeast IL Thu. Have 20-30% chances of showers and thunderstorms returning Tue and Tue night, with best chances Wed/Thu. Still very warm and humid Wed with highs in the mid to upper 80s while southeast IL near 90F where afternoon heat indices peak in upper 90s to near 100F. More cooler air filters in on Thu with highs around 80F central IL and lower 80s southeast IL. Dewpoints slip into the mid to upper 50s during Thu night. Have dry conditions returning by Friday with more comfortable temperature and humidity levels, with highs next Friday in the upper 70s central IL and near 80F southeast IL with dewpoints in the upper 50s and lower 60s. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 555 PM CDT FRI AUG 22 2014 Main concern tonight will once again be timing and coverage of showers and thunderstorms across the forecast area. Main synoptic scale frontal boundary was positioned well north of the area late this afternoon, however, there were several outflow boundaries noted in the latest analysis across parts of central Illinois. These features may be the focus for convection tonight but confidence on just when and coverage of storms is still very much in question. Any thunderstorm that does develop will have the capability of producing brief MVFR or IFR conditions with a quick recovery expected once the storm passes. Best timing appears to be in the 04z-08z time frame when convection spreads into parts of central IL. Whatever shower and thunderstorm activity we see into Saturday morning is expected to diminish, similar to what occurred today, by early to mid afternoon. Surface winds will be light southerly tonight at 3 to 8 kts, and then into the southwest at around 10kts by late Saturday morning or early afternoon. && .ILX WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY until 7 PM CDT Monday FOR ILZ042-047>054-056- 061>063-066>068-071>073. && $$ UPDATE...SMITH SHORT TERM...BARNES LONG TERM...07 AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
300 PM CDT THU AUG 21 2014 .DISCUSSION... 300 PM CDT SHORT TERM DISCUSSION TO BE ISSUED SHORTLY. LONG TERM...SUNDAY NIGHT THROUGH THURSDAY... THE MID SUMMER PATTERN WILL CONTINUE THROUGH AT LEAST WEDNESDAY NEXT WEEK BEFORE A STRONG UPPER TROUGH DIGS INTO THE GREAT LAKES REGION AND PUTS AN END TO THE EXTENDED STRETCH OF HEAT AND HUMIDITY. SUNDAY THROUGH TUESDAY... ENSEMBLES ARE EXHIBITING HIGH CONFIDENCE IN A 590+ DAM H5 RIDGE CENTERED OVER THE LOWER AND MID MS VALLEY SUNDAY NIGHT BEFORE BEING FLATTENED/SHUNTED EAST MONDAY INTO TUESDAY BY DISTURBANCES EMANATING FROM UPPER TROUGH FROM THE CANADIAN PRAIRIES TO THE NORTHERN ROCKIES. 850/925 MB CLIMO ON MONDAY-TUESDAY SUPPORTS HIGHS OF AT LEAST AROUND 90/LOW 90S...BUT MAIN UNCERTAINTY IS EXTENT OF CONVECTIVE ACTIVITY. SYNOPTIC SET-UP WITH FLATTENING RIDGE FAVORS MAINTAINING LOW TO MID CHANCE POPS ON MON-TUE AS SW FLOW DISTURBANCES COULD KICK OFF SHRA/TSRA IN PRESENCE OF MINIMAL CAPPING PER SOUNDINGS AND CONTINUED LOW-MID 70S DEW POINTS. ANY TSRA COULD PRODUCE HEAVY DOWNPOURS GIVEN PROGGED PWAT VALUES IN 1.5 TO 1.75 INCH RANGE. AT THIS TIME...IT WOULD APPEAR THAT MONDAY HAS A BETTER CHANCE TO HAVE LESS IN THE WAY OF CONVECTION AND CLOUDS. IF THIS OCCURS...FORECAST HIGH TEMPS COULD EVEN BE A BIT CONSERVATIVE...WITH GUIDANCE INDICATING 850 MB TEMPS IN THE LOW 20SC AND 925 MB TEMPS IN THE MID 20SC. BOTH DAYS COULD HAVE SOME LAKE COOLING GIVEN FAIRLY WEAK GRADIENT AND FLOW ALOFT. IF CLOUDS/CONVECTION DO NOT LIMIT WARMING POTENTIAL TOO MUCH...THEN BOTH DAYS ARE LIKELY TO HAVE HEAT INDEX VALUES APPROACHING OR EXCEEDING 100 DEGREES FOR AT LEAST PORTIONS OF THE CWA. TUESDAY NIGHT THROUGH THURSDAY... SPREAD INCREASES ON THE ENSEMBLES AND OPERATIONAL MODELS WITH RESPECT TO SPEED AT WHICH DEEP UPPER TROUGH AND ASSOCIATED SURFACE LOW DIG INTO GREAT LAKES REGION. HAVE CONCERN IN THIS PERIOD EVEN THIS FAR OUT FOR HEAVY RAIN/FLOODING POTENTIAL...AS POSITION OF CWA BETWEEN DEEP UPSTREAM TROUGH AND STRONG DOWNSTREAM RIDGE IS A SYNOPTICALLY FAVORABLE SET-UP FOR STRONG LLJ/MOISTURE TRANSPORT. PWAT VALUES COULD NEAR 2 INCHES. INCREASED FLOW ALOFT WILL ALSO RESULT IN INCREASED DEEP LAYER SHEAR SUPPORTIVE OF STRONG/SEVERE STORMS PENDING MESOSCALE COMING TOGETHER. 12Z ECMWF IS ACTUALLY ON FASTER END OF SPECTRUM COMPARED TO GFS AND ENSEMBLE MEAN WITH PROGRESSION OF SYSTEM...SO GENERALLY MAINTAINED CHANCE POPS FROM BLENDED GUIDANCE DUE TO UNCERTAINTY. TEMPERATURES WEDNESDAY WILL BE DICTATED BY TIMING...AS UPSTREAM AIR MASS IS MUCH COOLER...ESPECIALLY ON LATEST ECMWF. THURSDAY TEMPS COULD RANGE FROM NEAR TO SLIGHTLY BELOW SEASONABLE TO WELL BELOW NORMAL...BUT DID NOT STRAY AWAY FROM SMART BLEND. RC && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * TIMING ADDITIONAL THUNDERSTORM CHANCES TODAY...WITH A CHANCE LATE THIS AFTERNOON...AND AGAIN OVERNIGHT. * LOWER CEILINGS OR VISIBILITY FRIDAY MORNING * POTENTIAL EAST WINDS FRIDAY AFTERNOON BUT GENERALLY UNDER 10 KT KMD //DISCUSSION...UPDATED 18Z... THUNDER HAS REMAINED WEST AND NORTH WITH THE CURRENT BAND OF SHOWER ACTIVITY THAT WILL PUSH THROUGH NORTHEAST ILLINOIS IN THE NEXT FEW HOURS. THERE IS ANOTHER AREA OF THUNDERSTORMS THAT CONTINUES TO ORGANIZE IN EASTERN IOWA THAT WILL GET AN ADDITIONAL SHOVE EASTWARD LATER THIS AFTERNOON AS A SHORT WAVE IN WESTERN CENTRAL IOWA SPREADS INTO ILLINOIS AND THEN SOUTHEASTWARD INTO INDIANA THIS EVENING. THIS MAY BRING A PERIOD OF SHOWERS OR THUNDERSTORMS TO THE TERMINALS DURING THE LATE AFTERNOON INTO THE EARLY EVENING PERIOD. HAVE GONE WITH SHOWERS FOR NOW GIVEN RECENT TRENDS BUT THIS MAY BE A PERIOD DURING THE AFTERNOON-EARLY EVENING RUSH WHERE THERE MAY BE THUNDER IN THE VICINITY AND IS A PERIOD WE WILL MONITOR IN THE COMING HOURS. THEN THERE APPEARS TO BE A BREAK IN THE EVENING TIME FRAME AS UPPER LEVEL FORCING DIMINISHES. WARM AIR ADVECTION THEN RAMPS BACK UP IN WEST CENTRAL IOWA. IF THIS ACTIVITY GETS MOVING INTO ILLINOIS IT LOOKS TO COME THROUGH OVERNIGHT. THEREFORE PUSHED THE GOING PROB30 BACK TO ACCOUNT FOR THIS TIME FRAME. THERE MAY ALSO BE SOME LOWER CLOUDS OR REDUCED VISIBILITIES LATE TONIGHT INTO EARLY FRIDAY AFTER ADDITIONAL CONVECTIVE ACTIVITY WINDS DOWN AND WINDS SLACKEN. KMD //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM-HIGH IN PERIODS OF SHOWERS THIS AFTERNOON...HIGH IN NO THUNDER FOR THE NEXT FEW HOURS. LOW IN THUNDER CHANCES LATER THIS AFTERNOON. LOW- MEDIUM IN THUNDER CHANCES TONIGHT AND LOW IN TIMING. * LOW-MEDIUM IN WIND SPEEDS THIS AFTERNOON...HIGH IN DIRECTION EXCEPT AROUND SHOWERS. * LOW IN WIND DIRECTION FRIDAY AFTERNOON KMD //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... * FRIDAY NIGHT THROUGH WEDNESDAY...PERIODIC CHANCES FOR TSRA/SHRA WITH OCNL MVFR CIGS/VIS. KREIN && .MARINE... 205 PM CDT THE WEATHER PATTERN WILL NOT CHANGE MUCH OVER LAKE MICHIGAN THROUGH THIS WEEKEND WITH LOW PRESSURE ACROSS THE CENTRAL PLAINS AND HIGH PRESSURE OVER ONTARIO. A FRONT EXTENDING EAST FROM THE LOW IS PRESENTLY DRAPED ACROSS THE FAR SOUTHERN PART OF THE LAKE AND THIS WILL MOVE LITTLE THROUGH EARLY FRIDAY BEFORE SHIFTING BACK SOUTH OF THE LAKE ON FRIDAY NIGHT. SOME THUNDERSTORMS ACROSS THE SOUTHERN PART OF THE LAKE LATE THIS AFTERNOON MAY CAUSE SOME VARIABILITY AND SLIGHTLY ENHANCED GUSTS IN THE WINDS...BUT ANY OF THIS SHOULD BE TEMPORARY. THE WINDS WILL THEN TURN SOUTHERLY ACROSS THE ENTIRE LAKE BY SUNDAY WITH THE LOW PRESSURE LIFTING NORTH INTO SOUTHERN CANADA BY SUNDAY NIGHT. SPEEDS WILL INCREASE DURING THE MIDDLE OF NEXT WEEK BEFORE A SURFACE TROUGH / COOL FRONT PASSES. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 257 PM CDT Thu Aug 21 2014 .SHORT TERM...(This evening through Friday) ISSUED AT 255 PM CDT THU AUG 21 2014 18Z/1pm surface analysis shows stationary frontal boundary extending from northern Iowa to southern Lake Michigan. Scattered convection continues to develop and track along this boundary, mainly impacting locations north of the I-80 corridor. An outflow boundary is evident on visible satellite imagery dropping southeastward across eastern Iowa and this may trigger isolated showers/thunder across the far northwest KILX CWA this afternoon into the early evening. Aside from this possible convection, the next round of significant precip will likely hold off until late tonight when 30-35kt LLJ develops from the southern Plains northeastward into Iowa. As this jet interacts with the frontal boundary, a cluster of thunderstorms will develop across eastern Iowa/northwest Illinois toward midnight, then will track E/SE across north-central Illinois overnight. Models continue to struggle with exact placement and track of convection, with the 12z NAM once again appearing to be too aggressive with its southward push of precip into the CWA tonight. Prefer the Rapid Refresh model solution which keeps most of the convection confined to locations along/northeast of the I-74 corridor. As a result, will carry likely PoPs after midnight northeast of I-74, tapering down to just slight chances further south along a Springfield to Paris line. Thunderstorm complex will track into Indiana Friday morning, resulting in decreasing PoPs across the board. With frontal boundary well to the north and upper heights rising across the area, mainly dry weather will be on tap Friday afternoon. High temperatures will reach the upper 80s and lower 90s. These readings combined with dewpoints in the lower to middle 70s will produce heat index values of around 100 degrees, with readings approaching 105 degrees across the S/SE CWA, where a Heat Advisory will be issued beginning Friday afternoon. && .LONG TERM...(Friday night through Thursday) ISSUED AT 255 PM CDT THU AUG 21 2014 12Z forecast models continue to build a strong upper level ridge over IL this weekend and lingers over the Ohio River valley early next work week. This will bring the longest and strongest heat wave of the summer to central and southeast IL with highs in the low to mid 90s from Friday through Tue and dewpoints peaking in the mid 70s from late morning into early evening. This giving afternoon heat indices of 98-106F and highest in sw counties where a heat advisory will be issued from Friday afternoon through Monday afternoon. Heat indices could even peak around 105F sw counties this weekend. Southeast IL will continue to have heat indices of 100-105F Tuesday afternoon so heat advisory may need to be extended with future updates. Due to uncertainty of convection chances and possibly more cloud cover at times over ne counties Fri and Sat, especially from I-74 ne, kept them out of heat advisory but will issue SPS product to ahead heat indices reaching 100F or even a few degree higher at time through early next week. Another short wave riding se over top off upper level ridge across northern/ne IL could bring 20-30% chance of showers and thunderstorms to ne CWA especially from I-74 ne Friday night and then shifting further ne during the day Saturday with just slight pops ne areas. Upper level ridge appears strong enough over central/se IL to keep convection chances ne of area from Saturday night through Monday. Models have trended slower with bringing a frontal boundary se into NW IL Monday night/Tue and trimmed pops and confined them further nw during that time. Also went a bit warmer with highs Monday and Tuesday due to slower frontal movement and upper level ridge holding longer over central/se IL. Better chance of showers and thunderstorms appears to now be Wed/Thu time frame with upper level trof starting to dig more into the upper Midwest and driving front further southeast into central IL Wed and toward the Ohio river valley on Thursday. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) ISSUED AT 1241 PM CDT THU AUG 21 2014 Scattered convection continues to track along a nearly stationary frontal boundary draped across far northern Illinois/southern Wisconsin early this afternoon. This activity will remain north of the central Illinois terminals through this evening. Main aviation question will be when/where additional nocturnal convection will develop later tonight. Once again the NAM seems too aggressive in driving precip southward into the area tonight, while the HRRR is completely dry through 04z. Prefer a compromise solution as seen on the latest Rapid Refresh model, which features a cluster of showers/storms developing across eastern Iowa by around midnight, then tracking E/SE across north-central Illinois overnight. Based on this model, have introduced VCTS at the I-74 terminals between 07z and 09z. Further south, have gone completely dry at both KSPI and KDEC through the night. Once any early morning convection clears the area, dry weather is anticipated after 14z. && .ILX WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY from 1 PM Friday to 7 PM CDT Monday FOR ILZ042- 047>054-056-061>063-066>068-071>073. && $$ SHORT TERM...BARNES LONG TERM...07 AVIATION...BARNES
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
208 PM CDT THU AUG 21 2014 .DISCUSSION... 1155 AM CDT THE AFTERNOON FORECAST HAS BEEN UPDATED TO REFLECT COOLER TEMPERATURES AND INCREASE POPS FOR THE NORTHERN FORECAST AREA. IT REMAINS CHALLENGING TO GET VERY SPECIFIC WITH REGARD TO TIMING THUNDERSTORM CHANCES. EARLY THIS AFTERNOON...THE SYNOPTIC WARM FRONT EXTENDS FROM NORTHERN IA THROUGH FAR NORTHERN IL AND TO THE MI/IN BORDER. THIS FEATURE IS SOMEWHAT BAGGY OVER OUR AREA DUE TO OUTFLOW BOUNDARIES AND CLOUDS FROM EARLIER ACTIVITY KEEPING THE MAIN BAROCLINIC ZONE SOUTH OF THE WIND SHIFT AND MORE SO IN THE SOUTHERN FORECAST AREA. PROFILERS INDICATE 15 TO 25 KT WESTERLY FLOW IN THE 850-925MB LAYER WITH WEAK TO MODEST ISENTROPIC ASCENT ALONG THIS BOUNDARY. AREAS OF MORE FOCUSED ASCENT ARE BASICALLY IN TANDEM WITH MULTIPLE SHORT WAVES...WITH THE ONES OF INTEREST OVER SOUTHERN WI AND WESTERN/CENTRAL IA. THESE FEATURES WILL CONTINUE TO SUPPORT AREAS OF SHOWERS WORTHY OF LIKELY TO CATEGORICAL RAIN CHANCES FOR THE NORTHERN FORECAST AREA. ELEVATED INSTABILITY IS ON THE ORDER OF 400-700 J/KG PER THE 12Z DVN SOUNDING AND RAP ANALYSIS...SO THUNDER COVERAGE IS LIKELY TO REMAIN LESS THAN RAIN COVERAGE THROUGH EARLY AFTERNOON...AND AT TIMES HAS ONLY BEEN ISOLATED. THE WESTERN WAVE OVER IA IS ONE OF A LITTLE MORE INTEREST AS THAT COMES EASTWARD. HIGH RESOLUTION MODELS HAVE A SURPRISINGLY LARGE SPREAD IN SOLUTIONS WITH THIS...WITH THE RAP BEING A FURTHER SOUTH ONE. RADAR AND SATELLITE TRENDS ARE SUPPORTING THIS HOWEVER. AS THIS MOVES EASTWARD THERE COULD BE A RESULTANT UPTICK IN THUNDER COVERAGE DURING THE LATTER AFTERNOON INTO EARLY EVE...BUT LAPSE RATES ARE POOR AND LIKELY WILL CONTINUE TO BE SO...COMMON WITH A HIGH PWAT ATMOSPHERE AND NO SIGNIFICANT DIFFERENTIAL TEMPERATURE ADVECTION. THE BETTER WARM AIR ADVECTION AND MOISTURE TRANSPORT DEVELOP OVER THE MIDWEST LATER THIS EVENING...AND AN EVEN LARGER SPREAD IN MODELS EXIST WITH THIS. AS SUCH...HAVE NOT MADE ANY MAJOR CHANGES TO TONIGHTS POPS YET. THERE STILL LOOKS TO BE A HEAVY RAINFALL THREAT WITHIN THE GENERAL REGION...BUT SPECIFICS ARE QUITE DIFFICULT TO LOCK IN. THE BOUNDARY SHOULD STRUGGLE TO MOVE MUCH NORTHWARD THIS AFTERNOON DUE TO THE AREAS OF RAIN. THE SHOWERS AND WARM AIR ADVECTION ALONG THE FRONTAL ZONE WILL HELP SUPPORT CLOUDS AND KEEP TEMPERATURES COOLER. HIGHS LOOK TO STAY BELOW 80 FOR SOME COMMUNITIES IN NORTHERN IL. UPPER 80S ARE STILL FAVORED ACROSS THE FAR SOUTHERN FORECAST AREA WHERE SCATTERING OF CLOUDS AND INCREASING SOUTHWEST SURFACE FLOW WILL FURTHER WARMING. MTF //PREV DISCUSSION... 330 AM CDT SHORT TERM...THROUGH THURSDAY NIGHT... FOR THE REMAINDER OF THE OVERNIGHT HOURS...AN AREA OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED ALONG AN ELEVATED BAROCLINIC ZONE...NORTH OF A WARM FRONT THAT EXTENDS FROM LOW PRESSURE OVER SOUTH DAKOTA THROUGH CNTRL IL. THE THE CELL MOTION OF THESE STORMS IS TO THE SOUTHEAST AS UPPER RIDGING BUILDS OVER THE UPPER MISSISSIPPI VALLEY AND AN UPPER LOW SITE OVER GEORGIAN BAY. THE RIDGE AXIS SHOULD REMAIN IN PLACE ALONG THE MISSISSIPPI RIVER...SO FLOW ALOFT SHOULD REMAIN GENERALLY NWLY. EXPECT THAT PCPN COVERAGE THROUGH THE REMAINDER OF THE NIGHT SHOULD REMAIN GENERALLY SCATTERED OR IN SHORT LINES. WITH DAYTIME WARMING...ANTICIPATE THAT THE TSRA COVERAGE SHOULD INCREASE...BUT REMAIN FOCUSED ALONG THE ELEVATED BAROCLINIC ZONE WHICH SHOULD REMAIN OVER NRN IL/NWRN IN. WHILE THE SHORT RANGE MODELS HAVE NOT REALLY HANDLED THE CONVECTIVE TRENDS ALL THAT WELL OVER RECENT RUNS...THE LATEST HIGH RES GUIDANCE SUGGESTS THAT THERE COULD BE A LULL IN THE ACTIVITY DURG THE AFTERNOON HOURS WITH SOME WEAK SHORT WAVE RIDGING MOVING OVER THE REGION. HAVE MADE SOME ADJUSTMENT TO THE MAX TEMPS FOR TODAY AS WELL. EXPECT THAT THERE SHOULD BE MORE EXTENSIVE DEBRIS CLOUD OVER MUCH OF THE AREA...REMNANTS OF THE DECAYING CONVECTIVE ACTIVITY...SO HAVE BACKED OFF ON MAX TEMPS BY A FEW DEGREES EAST OF A LINE FROM DIXON TO GIBSON CITY...WHICH COINCIDES WITH THE ELEVATED BAROCLINIC ZONE. SO...WILL GO WITH HIGHS ARND 83-85F. THERE IS STILL THE POTENTIAL FOR THE FAR SOUTHWESTERN PORTIONS OF THE CWA TO SEE TEMPS IN THE UPPER 80S TO NEAR 90F AS THAT PORTION OF THE CWA LIES SOUTH OF THE MAIN BAROCLINIC ZONE AND THERE SHOULD BE LESS CLOUD COVER AND MORE OPPORTUNITY FOR TEMPS TO CLIMB A LITTLE HIGHER. LATEST THINKING IS THAT THE BEST OPPORTUNITY FOR MORE ORGANIZED CONVECTION...INCLUDING THE CHANCE FOR LOCALLY HEAVY RAINFALL...WILL BE DURG THE LATE EVENING THROUGH THE OVERNIGHT HOURS. THE MODELS ARE KEYING ON A SHORTWAVE CURRENTLY OVER KANSAS AND NEBRASKA TO RIDE UP THE NWRN SIDE OF THE RIDGE THURSDAY AFTERNOON...OVERTOP THE RIDGE EARLY THURSDAY EVENING AND THEN DIVE SOUTHEAST ACROSS NRN IL/IN LATE THURSDAY EVENING AND OVERNIGHT THURSDAY NIGHT. FOLLOWING THIS TREND...HAVE GONE WITH CATEGORICAL POPS OVER THE NRN PORTIONS OF THE CWA THIS EVENING AND LIKELY POPS FOR MUCH OF THE AREA FOR THE PERIOD FROM 00Z-12Z FRIDAY. THE THREAT FOR LOCALLY HEAVY RAINFALL IS STILL PRESENT AS PWATS WILL BE SLIGHTLY IN EXCESS OF 2 INCHES. HOWEVER...DO NOT EXPECT A WIDESPREAD FLOOD THREAT AS THUNDERSTORMS SHOULD BE PROGRESSIVE...BUT LOCALLY HEAVY RAINFALL COULD CAUSE SOME URBAN AND SMALL STREAM TYPE FLOODING ISSUES. KREIN FRIDAY THROUGH SUNDAY... MAIN FOCUS WILL BE ON CONVECTIVE CHANCES...WHICH WILL ALSO PLAY A PIVOTAL ROLE ON TEMPS/HEAT INDEX VALUES FOR THE FRI-SUN STRETCH. GUIDANCE CONTINUES TO FAVOR A SLIGHT FLATTENING IN THE MID-LVL RIDGE FRI...WHICH COULD SETUP THE ATMOSPHERIC RIVER OVER THE CWFA ORIENTED FROM IOWA EAST THROUGH SOUTHERN WISC/NORTHERN IL...STRETCHING EAST INTO NORTHERN IN. THE LOCAL ARW8KM HAS CONTINUED TO BE A LITTLE LESS EXCITED THAN SREF/NAM...HOWEVER THE THEME DOES APPEAR TO BE CONSISTENT. CONFIDENCE HAS DIMINISHED A LITTLE FOR FRI...BUT HAVE ONLY MADE MINOR ADJUSTMENTS TO THE GOING FORECAST. IF LESS CONVECTION/CLOUDS ARE PRESENT FRI...THEN TEMPS SHUD EASILY WARM TO THE UPR 80S/ARND 90 WITH HEAT INDEX VALUES ARND 100 FOR MANY LOCATIONS. PERHAPS EVEN THE LOW 100S SOUTH OF I-80. THE FIRST WAVE OF ACTIVITY SHUD BE MAINLY IN THE MORNING HOURS...SLIDING EAST/SOUTHEAST. THEN THE THETA-E RIDGE LIFTS NORTH INTO IOWA...WITH ANOTHER LOBE OF VORTICITY POISED TO RIDE ALONG THIS FEATURE AND SLIDE SOUTHEAST ACROSS THE FORECAST AREA LATE FRI/EARLY SAT. OVER THE NEXT SEVERAL DAYS...SAT IS LIKELY THE MOST CHALLENGING. AT THIS TIME GUIDANCE HAS COME INTO BETTER AGREEMENT THAT THE FRONTAL BOUNDARY WILL SLIDE BACK SOUTH ACROSS THE FORECAST AREA...ALLOWING LLVL FLOW TO TURN NORTHEAST/EASTERLY WITH CLOUDS LINGERING MUCH OF THE DAY. WITH THIS SCENARIO...SAT WILL LIKELY SEE TEMPS GENERALLY IN THE MID/UPR 80S BUT COULD BE SLIGHTLY LOWER DEPENDING ON HOW THICK CLOUD COVER WILL BE. FORTUNATELY THIS WILL KEEP HEAT INDEX VALUES BELOW 95 DEG FOR MUCH OF THE AREA. THEN PROGRESSING TOWARDS THE SECOND HALF OF THE WEEKEND AND SUN STILL IS ON TRACK TO BE THE WARMEST DAY OF THE STRETCH. THE MID-LVL RIDGE REMAINS POISED TO BUILD BACK INTO THE REGION...LIFTING THE WARM FRONTAL BOUNDARY NORTH OF THE FORECAST AREA SUN. THIS SHUD KEEP MOST OF THE CONVECTIVE CHANCES DISPLACED NORTH. SOUNDINGS SUGGEST THE MID-LVLS WILL BE MUCH WARMER AS WELL...WHICH COULD BE ENOUGH TO EITHER LIMIT OR CAP THE ENVIRONMENT FROM SEEING CONVECTION DEVELOP SUN. HAVE HEDGED POPS IN THIS DIRECTION...WITH A DRY FORECAST ACROSS MUCH OF THE FORECAST AREA SUN. SFC TEMPS SHUD EASILY WARM...WITH HIGHS ARND 90 TO POSSIBLY THE LOW 90S. HOWEVER...LLVL MOISTURE WILL REMAIN HIGH AS WELL WITH DEW PTS IN THE 72-74 DEG RANGE. THE COMBINATION WILL LIKELY PRODUCE HEAT INDEX VALUES IN THE UPR 90S TO PERHAPS AS HIGH AS 105 SUN AFTN FOR AREAS SOUTH OF I-80. MONDAY THROUGH WEDNESDAY... GUIDANCE HAS CONTINUED TO BE LESS EXCITED ABOUT DEPARTING OR WEAKENING THE MID-LVL RIDGE VERY EARLY NEXT WEEK. AS A RESULT MON AND PERHAPS TUE LOOK TO MAINTAIN THE HEAT. FORTUNATELY LLVL MOISTURE DOES APPEAR TO BE A LITTLE LESS THAN THE PRIOR WEEKEND...HOWEVER HEAT INDEX VALUES ARE STILL PROGGED MON TO REACH THE MID TO PERHAPS UPR 90S. LLVL MOISTURE BEGINS TO DECLINE FURTHER FOR TUE...WHICH COULD KEEP TEMPS GENERALLY IN THE MID/UPR 80S. THROUGHOUT THE FIRST HALF OF NEXT WEEK PERIODIC CHANCES FOR CONVECTION REMAIN. THE FINAL FEW PERIODS ENSEMBLES HAVE THE IDEA THAT SOME WEAKENING TO THE ROBUST RIDGE WILL OCCUR. BEACHLER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * TIMING ADDITIONAL THUNDERSTORM CHANCES TODAY...WITH A CHANCE LATE THIS AFTERNOON...AND AGAIN OVERNIGHT. * LOWER CEILINGS OR VISIBILITY FRIDAY MORNING * POTENTIAL EAST WINDS FRIDAY AFTERNOON BUT GENERALLY UNDER 10 KT KMD //DISCUSSION...UPDATED 18Z... THUNDER HAS REMAINED WEST AND NORTH WITH THE CURRENT BAND OF SHOWER ACTIVITY THAT WILL PUSH THROUGH NORTHEAST ILLINOIS IN THE NEXT FEW HOURS. THERE IS ANOTHER AREA OF THUNDERSTORMS THAT CONTINUES TO ORGANIZE IN EASTERN IOWA THAT WILL GET AN ADDITIONAL SHOVE EASTWARD LATER THIS AFTERNOON AS A SHORT WAVE IN WESTERN CENTRAL IOWA SPREADS INTO ILLINOIS AND THEN SOUTHEASTWARD INTO INDIANA THIS EVENING. THIS MAY BRING A PERIOD OF SHOWERS OR THUNDERSTORMS TO THE TERMINALS DURING THE LATE AFTERNOON INTO THE EARLY EVENING PERIOD. HAVE GONE WITH SHOWERS FOR NOW GIVEN RECENT TRENDS BUT THIS MAY BE A PERIOD DURING THE AFTERNOON-EARLY EVENING RUSH WHERE THERE MAY BE THUNDER IN THE VICINITY AND IS A PERIOD WE WILL MONITOR IN THE COMING HOURS. THEN THERE APPEARS TO BE A BREAK IN THE EVENING TIME FRAME AS UPPER LEVEL FORCING DIMINISHES. WARM AIR ADVECTION THEN RAMPS BACK UP IN WEST CENTRAL IOWA. IF THIS ACTIVITY GETS MOVING INTO ILLINOIS IT LOOKS TO COME THROUGH OVERNIGHT. THEREFORE PUSHED THE GOING PROB30 BACK TO ACCOUNT FOR THIS TIME FRAME. THERE MAY ALSO BE SOME LOWER CLOUDS OR REDUCED VISIBILITIES LATE TONIGHT INTO EARLY FRIDAY AFTER ADDITIONAL CONVECTIVE ACTIVITY WINDS DOWN AND WINDS SLACKEN. KMD //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM-HIGH IN PERIODS OF SHOWERS THIS AFTERNOON...HIGH IN NO THUNDER FOR THE NEXT FEW HOURS. LOW IN THUNDER CHANCES LATER THIS AFTERNOON. LOW- MEDIUM IN THUNDER CHANCES TONIGHT AND LOW IN TIMING. * LOW-MEDIUM IN WIND SPEEDS THIS AFTERNOON...HIGH IN DIRECTION EXCEPT AROUND SHOWERS. * LOW IN WIND DIRECTION FRIDAY AFTERNOON KMD //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... * FRIDAY NIGHT THROUGH WEDNESDAY...PERIODIC CHANCES FOR TSRA/SHRA WITH OCNL MVFR CIGS/VIS. KREIN && .MARINE... 205 PM CDT THE WEATHER PATTERN WILL NOT CHANGE MUCH OVER LAKE MICHIGAN THROUGH THIS WEEKEND WITH LOW PRESSURE ACROSS THE CENTRAL PLAINS AND HIGH PRESSURE OVER ONTARIO. A FRONT EXTENDING EAST FROM THE LOW IS PRESENTLY DRAPED ACROSS THE FAR SOUTHERN PART OF THE LAKE AND THIS WILL MOVE LITTLE THROUGH EARLY FRIDAY BEFORE SHIFTING BACK SOUTH OF THE LAKE ON FRIDAY NIGHT. SOME THUNDERSTORMS ACROSS THE SOUTHERN PART OF THE LAKE LATE THIS AFTERNOON MAY CAUSE SOME VARIABILITY AND SLIGHTLY ENHANCED GUSTS IN THE WINDS...BUT ANY OF THIS SHOULD BE TEMPORARY. THE WINDS WILL THEN TURN SOUTHERLY ACROSS THE ENTIRE LAKE BY SUNDAY WITH THE LOW PRESSURE LIFTING NORTH INTO SOUTHERN CANADA BY SUNDAY NIGHT. SPEEDS WILL INCREASE DURING THE MIDDLE OF NEXT WEEK BEFORE A SURFACE TROUGH / COOL FRONT PASSES. MTF && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
115 PM CDT THU AUG 21 2014 .DISCUSSION... 1155 AM CDT THE AFTERNOON FORECAST HAS BEEN UPDATED TO REFLECT COOLER TEMPERATURES AND INCREASE POPS FOR THE NORTHERN FORECAST AREA. IT REMAINS CHALLENGING TO GET VERY SPECIFIC WITH REGARD TO TIMING THUNDERSTORM CHANCES. EARLY THIS AFTERNOON...THE SYNOPTIC WARM FRONT EXTENDS FROM NORTHERN IA THROUGH FAR NORTHERN IL AND TO THE MI/IN BORDER. THIS FEATURE IS SOMEWHAT BAGGY OVER OUR AREA DUE TO OUTFLOW BOUNDARIES AND CLOUDS FROM EARLIER ACTIVITY KEEPING THE MAIN BAROCLINIC ZONE SOUTH OF THE WIND SHIFT AND MORE SO IN THE SOUTHERN FORECAST AREA. PROFILERS INDICATE 15 TO 25 KT WESTERLY FLOW IN THE 850-925MB LAYER WITH WEAK TO MODEST ISENTROPIC ASCENT ALONG THIS BOUNDARY. AREAS OF MORE FOCUSED ASCENT ARE BASICALLY IN TANDEM WITH MULTIPLE SHORT WAVES...WITH THE ONES OF INTEREST OVER SOUTHERN WI AND WESTERN/CENTRAL IA. THESE FEATURES WILL CONTINUE TO SUPPORT AREAS OF SHOWERS WORTHY OF LIKELY TO CATEGORICAL RAIN CHANCES FOR THE NORTHERN FORECAST AREA. ELEVATED INSTABILITY IS ON THE ORDER OF 400-700 J/KG PER THE 12Z DVN SOUNDING AND RAP ANALYSIS...SO THUNDER COVERAGE IS LIKELY TO REMAIN LESS THAN RAIN COVERAGE THROUGH EARLY AFTERNOON...AND AT TIMES HAS ONLY BEEN ISOLATED. THE WESTERN WAVE OVER IA IS ONE OF A LITTLE MORE INTEREST AS THAT COMES EASTWARD. HIGH RESOLUTION MODELS HAVE A SURPRISINGLY LARGE SPREAD IN SOLUTIONS WITH THIS...WITH THE RAP BEING A FURTHER SOUTH ONE. RADAR AND SATELLITE TRENDS ARE SUPPORTING THIS HOWEVER. AS THIS MOVES EASTWARD THERE COULD BE A RESULTANT UPTICK IN THUNDER COVERAGE DURING THE LATTER AFTERNOON INTO EARLY EVE...BUT LAPSE RATES ARE POOR AND LIKELY WILL CONTINUE TO BE SO...COMMON WITH A HIGH PWAT ATMOSPHERE AND NO SIGNIFICANT DIFFERENTIAL TEMPERATURE ADVECTION. THE BETTER WARM AIR ADVECTION AND MOISTURE TRANSPORT DEVELOP OVER THE MIDWEST LATER THIS EVENING...AND AN EVEN LARGER SPREAD IN MODELS EXIST WITH THIS. AS SUCH...HAVE NOT MADE ANY MAJOR CHANGES TO TONIGHTS POPS YET. THERE STILL LOOKS TO BE A HEAVY RAINFALL THREAT WITHIN THE GENERAL REGION...BUT SPECIFICS ARE QUITE DIFFICULT TO LOCK IN. THE BOUNDARY SHOULD STRUGGLE TO MOVE MUCH NORTHWARD THIS AFTERNOON DUE TO THE AREAS OF RAIN. THE SHOWERS AND WARM AIR ADVECTION ALONG THE FRONTAL ZONE WILL HELP SUPPORT CLOUDS AND KEEP TEMPERATURES COOLER. HIGHS LOOK TO STAY BELOW 80 FOR SOME COMMUNITIES IN NORTHERN IL. UPPER 80S ARE STILL FAVORED ACROSS THE FAR SOUTHERN FORECAST AREA WHERE SCATTERING OF CLOUDS AND INCREASING SOUTHWEST SURFACE FLOW WILL FURTHER WARMING. MTF //PREV DISCUSSION... 330 AM CDT SHORT TERM...THROUGH THURSDAY NIGHT... FOR THE REMAINDER OF THE OVERNIGHT HOURS...AN AREA OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED ALONG AN ELEVATED BAROCLINIC ZONE...NORTH OF A WARM FRONT THAT EXTENDS FROM LOW PRESSURE OVER SOUTH DAKOTA THROUGH CNTRL IL. THE THE CELL MOTION OF THESE STORMS IS TO THE SOUTHEAST AS UPPER RIDGING BUILDS OVER THE UPPER MISSISSIPPI VALLEY AND AN UPPER LOW SITE OVER GEORGIAN BAY. THE RIDGE AXIS SHOULD REMAIN IN PLACE ALONG THE MISSISSIPPI RIVER...SO FLOW ALOFT SHOULD REMAIN GENERALLY NWLY. EXPECT THAT PCPN COVERAGE THROUGH THE REMAINDER OF THE NIGHT SHOULD REMAIN GENERALLY SCATTERED OR IN SHORT LINES. WITH DAYTIME WARMING...ANTICIPATE THAT THE TSRA COVERAGE SHOULD INCREASE...BUT REMAIN FOCUSED ALONG THE ELEVATED BAROCLINIC ZONE WHICH SHOULD REMAIN OVER NRN IL/NWRN IN. WHILE THE SHORT RANGE MODELS HAVE NOT REALLY HANDLED THE CONVECTIVE TRENDS ALL THAT WELL OVER RECENT RUNS...THE LATEST HIGH RES GUIDANCE SUGGESTS THAT THERE COULD BE A LULL IN THE ACTIVITY DURG THE AFTERNOON HOURS WITH SOME WEAK SHORT WAVE RIDGING MOVING OVER THE REGION. HAVE MADE SOME ADJUSTMENT TO THE MAX TEMPS FOR TODAY AS WELL. EXPECT THAT THERE SHOULD BE MORE EXTENSIVE DEBRIS CLOUD OVER MUCH OF THE AREA...REMNANTS OF THE DECAYING CONVECTIVE ACTIVITY...SO HAVE BACKED OFF ON MAX TEMPS BY A FEW DEGREES EAST OF A LINE FROM DIXON TO GIBSON CITY...WHICH COINCIDES WITH THE ELEVATED BAROCLINIC ZONE. SO...WILL GO WITH HIGHS ARND 83-85F. THERE IS STILL THE POTENTIAL FOR THE FAR SOUTHWESTERN PORTIONS OF THE CWA TO SEE TEMPS IN THE UPPER 80S TO NEAR 90F AS THAT PORTION OF THE CWA LIES SOUTH OF THE MAIN BAROCLINIC ZONE AND THERE SHOULD BE LESS CLOUD COVER AND MORE OPPORTUNITY FOR TEMPS TO CLIMB A LITTLE HIGHER. LATEST THINKING IS THAT THE BEST OPPORTUNITY FOR MORE ORGANIZED CONVECTION...INCLUDING THE CHANCE FOR LOCALLY HEAVY RAINFALL...WILL BE DURG THE LATE EVENING THROUGH THE OVERNIGHT HOURS. THE MODELS ARE KEYING ON A SHORTWAVE CURRENTLY OVER KANSAS AND NEBRASKA TO RIDE UP THE NWRN SIDE OF THE RIDGE THURSDAY AFTERNOON...OVERTOP THE RIDGE EARLY THURSDAY EVENING AND THEN DIVE SOUTHEAST ACROSS NRN IL/IN LATE THURSDAY EVENING AND OVERNIGHT THURSDAY NIGHT. FOLLOWING THIS TREND...HAVE GONE WITH CATEGORICAL POPS OVER THE NRN PORTIONS OF THE CWA THIS EVENING AND LIKELY POPS FOR MUCH OF THE AREA FOR THE PERIOD FROM 00Z-12Z FRIDAY. THE THREAT FOR LOCALLY HEAVY RAINFALL IS STILL PRESENT AS PWATS WILL BE SLIGHTLY IN EXCESS OF 2 INCHES. HOWEVER...DO NOT EXPECT A WIDESPREAD FLOOD THREAT AS THUNDERSTORMS SHOULD BE PROGRESSIVE...BUT LOCALLY HEAVY RAINFALL COULD CAUSE SOME URBAN AND SMALL STREAM TYPE FLOODING ISSUES. KREIN FRIDAY THROUGH SUNDAY... MAIN FOCUS WILL BE ON CONVECTIVE CHANCES...WHICH WILL ALSO PLAY A PIVOTAL ROLE ON TEMPS/HEAT INDEX VALUES FOR THE FRI-SUN STRETCH. GUIDANCE CONTINUES TO FAVOR A SLIGHT FLATTENING IN THE MID-LVL RIDGE FRI...WHICH COULD SETUP THE ATMOSPHERIC RIVER OVER THE CWFA ORIENTED FROM IOWA EAST THROUGH SOUTHERN WISC/NORTHERN IL...STRETCHING EAST INTO NORTHERN IN. THE LOCAL ARW8KM HAS CONTINUED TO BE A LITTLE LESS EXCITED THAN SREF/NAM...HOWEVER THE THEME DOES APPEAR TO BE CONSISTENT. CONFIDENCE HAS DIMINISHED A LITTLE FOR FRI...BUT HAVE ONLY MADE MINOR ADJUSTMENTS TO THE GOING FORECAST. IF LESS CONVECTION/CLOUDS ARE PRESENT FRI...THEN TEMPS SHUD EASILY WARM TO THE UPR 80S/ARND 90 WITH HEAT INDEX VALUES ARND 100 FOR MANY LOCATIONS. PERHAPS EVEN THE LOW 100S SOUTH OF I-80. THE FIRST WAVE OF ACTIVITY SHUD BE MAINLY IN THE MORNING HOURS...SLIDING EAST/SOUTHEAST. THEN THE THETA-E RIDGE LIFTS NORTH INTO IOWA...WITH ANOTHER LOBE OF VORTICITY POISED TO RIDE ALONG THIS FEATURE AND SLIDE SOUTHEAST ACROSS THE FORECAST AREA LATE FRI/EARLY SAT. OVER THE NEXT SEVERAL DAYS...SAT IS LIKELY THE MOST CHALLENGING. AT THIS TIME GUIDANCE HAS COME INTO BETTER AGREEMENT THAT THE FRONTAL BOUNDARY WILL SLIDE BACK SOUTH ACROSS THE FORECAST AREA...ALLOWING LLVL FLOW TO TURN NORTHEAST/EASTERLY WITH CLOUDS LINGERING MUCH OF THE DAY. WITH THIS SCENARIO...SAT WILL LIKELY SEE TEMPS GENERALLY IN THE MID/UPR 80S BUT COULD BE SLIGHTLY LOWER DEPENDING ON HOW THICK CLOUD COVER WILL BE. FORTUNATELY THIS WILL KEEP HEAT INDEX VALUES BELOW 95 DEG FOR MUCH OF THE AREA. THEN PROGRESSING TOWARDS THE SECOND HALF OF THE WEEKEND AND SUN STILL IS ON TRACK TO BE THE WARMEST DAY OF THE STRETCH. THE MID-LVL RIDGE REMAINS POISED TO BUILD BACK INTO THE REGION...LIFTING THE WARM FRONTAL BOUNDARY NORTH OF THE FORECAST AREA SUN. THIS SHUD KEEP MOST OF THE CONVECTIVE CHANCES DISPLACED NORTH. SOUNDINGS SUGGEST THE MID-LVLS WILL BE MUCH WARMER AS WELL...WHICH COULD BE ENOUGH TO EITHER LIMIT OR CAP THE ENVIRONMENT FROM SEEING CONVECTION DEVELOP SUN. HAVE HEDGED POPS IN THIS DIRECTION...WITH A DRY FORECAST ACROSS MUCH OF THE FORECAST AREA SUN. SFC TEMPS SHUD EASILY WARM...WITH HIGHS ARND 90 TO POSSIBLY THE LOW 90S. HOWEVER...LLVL MOISTURE WILL REMAIN HIGH AS WELL WITH DEW PTS IN THE 72-74 DEG RANGE. THE COMBINATION WILL LIKELY PRODUCE HEAT INDEX VALUES IN THE UPR 90S TO PERHAPS AS HIGH AS 105 SUN AFTN FOR AREAS SOUTH OF I-80. MONDAY THROUGH WEDNESDAY... GUIDANCE HAS CONTINUED TO BE LESS EXCITED ABOUT DEPARTING OR WEAKENING THE MID-LVL RIDGE VERY EARLY NEXT WEEK. AS A RESULT MON AND PERHAPS TUE LOOK TO MAINTAIN THE HEAT. FORTUNATELY LLVL MOISTURE DOES APPEAR TO BE A LITTLE LESS THAN THE PRIOR WEEKEND...HOWEVER HEAT INDEX VALUES ARE STILL PROGGED MON TO REACH THE MID TO PERHAPS UPR 90S. LLVL MOISTURE BEGINS TO DECLINE FURTHER FOR TUE...WHICH COULD KEEP TEMPS GENERALLY IN THE MID/UPR 80S. THROUGHOUT THE FIRST HALF OF NEXT WEEK PERIODIC CHANCES FOR CONVECTION REMAIN. THE FINAL FEW PERIODS ENSEMBLES HAVE THE IDEA THAT SOME WEAKENING TO THE ROBUST RIDGE WILL OCCUR. BEACHLER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * TIMING ADDITIONAL THUNDERSTORM CHANCES TODAY...WITH A CHANCE LATE THIS AFTERNOON...AND AGAIN OVERNIGHT. * LOWER CEILINGS OR VISIBILITY FRIDAY MORNING * POTENTIAL EAST WINDS FRIDAY AFTERNOON BUT GENERALLY UNDER 10 KT KMD //DISCUSSION...UPDATED 18Z... THUNDER HAS REMAINED WEST AND NORTH WITH THE CURRENT BAND OF SHOWER ACTIVITY THAT WILL PUSH THROUGH NORTHEAST ILLINOIS IN THE NEXT FEW HOURS. THERE IS ANOTHER AREA OF THUNDERSTORMS THAT CONTINUES TO ORGANIZE IN EASTERN IOWA THAT WILL GET AN ADDITIONAL SHOVE EASTWARD LATER THIS AFTERNOON AS A SHORT WAVE IN WESTERN CENTRAL IOWA SPREADS INTO ILLINOIS AND THEN SOUTHEASTWARD INTO INDIANA THIS EVENING. THIS MAY BRING A PERIOD OF SHOWERS OR THUNDERSTORMS TO THE TERMINALS DURING THE LATE AFTERNOON INTO THE EARLY EVENING PERIOD. HAVE GONE WITH SHOWERS FOR NOW GIVEN RECENT TRENDS BUT THIS MAY BE A PERIOD DURING THE AFTERNOON-EARLY EVENING RUSH WHERE THERE MAY BE THUNDER IN THE VICINITY AND IS A PERIOD WE WILL MONITOR IN THE COMING HOURS. THEN THERE APPEARS TO BE A BREAK IN THE EVENING TIME FRAME AS UPPER LEVEL FORCING DIMINISHES. WARM AIR ADVECTION THEN RAMPS BACK UP IN WEST CENTRAL IOWA. IF THIS ACTIVITY GETS MOVING INTO ILLINOIS IT LOOKS TO COME THROUGH OVERNIGHT. THEREFORE PUSHED THE GOING PROB30 BACK TO ACCOUNT FOR THIS TIME FRAME. THERE MAY ALSO BE SOME LOWER CLOUDS OR REDUCED VISIBILITIES LATE TONIGHT INTO EARLY FRIDAY AFTER ADDITIONAL CONVECTIVE ACTIVITY WINDS DOWN AND WINDS SLACKEN. KMD //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM-HIGH IN PERIODS OF SHOWERS THIS AFTERNOON...HIGH IN NO THUNDER FOR THE NEXT FEW HOURS. LOW IN THUNDER CHANCES LATER THIS AFTERNOON. LOW- MEDIUM IN THUNDER CHANCES TONIGHT AND LOW IN TIMING. * LOW-MEDIUM IN WIND SPEEDS THIS AFTERNOON...HIGH IN DIRECTION EXCEPT AROUND SHOWERS. * LOW IN WIND DIRECTION FRIDAY AFTERNOON KMD //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... * FRIDAY NIGHT THROUGH WEDNESDAY...PERIODIC CHANCES FOR TSRA/SHRA WITH OCNL MVFR CIGS/VIS. KREIN && .MARINE... 310 AM CDT NOT MUCH IN THE WAY OF A GRADIENT FOR THE NEXT SEVERAL DAYS...WITH WEAK SYSTEMS EXPECTED. HIGH PRESSURE OVER QUEBEC AND A SERIES OF WEAK TROUGHS OVER THE NORTHERN PLAINS. THERE WILL BE A QUASI- STATIONARY FRONTAL BOUNDARY THAT WILL MEANDER NORTH AND SOUTH ACROSS LAKE MICHIGAN...ALLOWING WINDS TO CHANGE DIRECTION BUT STILL NOT EXPECTING MUCH OF A WIND GRADIENT TO DEVELOP. THE HIGHEST WINDS WILL LIKELY BE ASSOCIATED WITH ANY THUNDERSTORMS THAT CAN PRODUCE BRIEF GUSTS. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
1158 AM CDT THU AUG 21 2014 .DISCUSSION... 1155 AM CDT THE AFTERNOON FORECAST HAS BEEN UPDATED TO REFLECT COOLER TEMPERATURES AND INCREASE POPS FOR THE NORTHERN FORECAST AREA. IT REMAINS CHALLENGING TO GET VERY SPECIFIC WITH REGARD TO TIMING THUNDERSTORM CHANCES. EARLY THIS AFTERNOON...THE SYNOPTIC WARM FRONT EXTENDS FROM NORTHERN IA THROUGH FAR NORTHERN IL AND TO THE MI/IN BORDER. THIS FEATURE IS SOMEWHAT BAGGY OVER OUR AREA DUE TO OUTFLOW BOUNDARIES AND CLOUDS FROM EARLIER ACTIVITY KEEPING THE MAIN BAROCLINIC ZONE SOUTH OF THE WIND SHIFT AND MORE SO IN THE SOUTHERN FORECAST AREA. PROFILERS INDICATE 15 TO 25 KT WESTERLY FLOW IN THE 850-925MB LAYER WITH WEAK TO MODEST ISENTROPIC ASCENT ALONG THIS BOUNDARY. AREAS OF MORE FOCUSED ASCENT ARE BASICALLY IN TANDEM WITH MULTIPLE SHORT WAVES...WITH THE ONES OF INTEREST OVER SOUTHERN WI AND WESTERN/CENTRAL IA. THESE FEATURES WILL CONTINUE TO SUPPORT AREAS OF SHOWERS WORTHY OF LIKELY TO CATEGORICAL RAIN CHANCES FOR THE NORTHERN FORECAST AREA. ELEVATED INSTABILITY IS ON THE ORDER OF 400-700 J/KG PER THE 12Z DVN SOUNDING AND RAP ANALYSIS...SO THUNDER COVERAGE IS LIKELY TO REMAIN LESS THAN RAIN COVERAGE THROUGH EARLY AFTERNOON...AND AT TIMES HAS ONLY BEEN ISOLATED. THE WESTERN WAVE OVER IA IS ONE OF A LITTLE MORE INTEREST AS THAT COMES EASTWARD. HIGH RESOLUTION MODELS HAVE A SURPRISINGLY LARGE SPREAD IN SOLUTIONS WITH THIS...WITH THE RAP BEING A FURTHER SOUTH ONE. RADAR AND SATELLITE TRENDS ARE SUPPORTING THIS HOWEVER. AS THIS MOVES EASTWARD THERE COULD BE A RESULTANT UPTICK IN THUNDER COVERAGE DURING THE LATTER AFTERNOON INTO EARLY EVE...BUT LAPSE RATES ARE POOR AND LIKELY WILL CONTINUE TO BE SO...COMMON WITH A HIGH PWAT ATMOSPHERE AND NO SIGNIFICANT DIFFERENTIAL TEMPERATURE ADVECTION. THE BETTER WARM AIR ADVECTION AND MOISTURE TRANSPORT DEVELOP OVER THE MIDWEST LATER THIS EVENING...AND AN EVEN LARGER SPREAD IN MODELS EXIST WITH THIS. AS SUCH...HAVE NOT MADE ANY MAJOR CHANGES TO TONIGHTS POPS YET. THERE STILL LOOKS TO BE A HEAVY RAINFALL THREAT WITHIN THE GENERAL REGION...BUT SPECIFICS ARE QUITE DIFFICULT TO LOCK IN. THE BOUNDARY SHOULD STRUGGLE TO MOVE MUCH NORTHWARD THIS AFTERNOON DUE TO THE AREAS OF RAIN. THE SHOWERS AND WARM AIR ADVECTION ALONG THE FRONTAL ZONE WILL HELP SUPPORT CLOUDS AND KEEP TEMPERATURES COOLER. HIGHS LOOK TO STAY BELOW 80 FOR SOME COMMUNITIES IN NORTHERN IL. UPPER 80S ARE STILL FAVORED ACROSS THE FAR SOUTHERN FORECAST AREA WHERE SCATTERING OF CLOUDS AND INCREASING SOUTHWEST SURFACE FLOW WILL FURTHER WARMING. MTF && .PREV DISCUSSION... 330 AM CDT SHORT TERM...THROUGH THURSDAY NIGHT... FOR THE REMAINDER OF THE OVERNIGHT HOURS...AN AREA OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED ALONG AN ELEVATED BAROCLINIC ZONE...NORTH OF A WARM FRONT THAT EXTENDS FROM LOW PRESSURE OVER SOUTH DAKOTA THROUGH CNTRL IL. THE THE CELL MOTION OF THESE STORMS IS TO THE SOUTHEAST AS UPPER RIDGING BUILDS OVER THE UPPER MISSISSIPPI VALLEY AND AN UPPER LOW SITE OVER GEORGIAN BAY. THE RIDGE AXIS SHOULD REMAIN IN PLACE ALONG THE MISSISSIPPI RIVER...SO FLOW ALOFT SHOULD REMAIN GENERALLY NWLY. EXPECT THAT PCPN COVERAGE THROUGH THE REMAINDER OF THE NIGHT SHOULD REMAIN GENERALLY SCATTERED OR IN SHORT LINES. WITH DAYTIME WARMING...ANTICIPATE THAT THE TSRA COVERAGE SHOULD INCREASE...BUT REMAIN FOCUSED ALONG THE ELEVATED BAROCLINIC ZONE WHICH SHOULD REMAIN OVER NRN IL/NWRN IN. WHILE THE SHORT RANGE MODELS HAVE NOT REALLY HANDLED THE CONVECTIVE TRENDS ALL THAT WELL OVER RECENT RUNS...THE LATEST HIGH RES GUIDANCE SUGGESTS THAT THERE COULD BE A LULL IN THE ACTIVITY DURG THE AFTERNOON HOURS WITH SOME WEAK SHORT WAVE RIDGING MOVING OVER THE REGION. HAVE MADE SOME ADJUSTMENT TO THE MAX TEMPS FOR TODAY AS WELL. EXPECT THAT THERE SHOULD BE MORE EXTENSIVE DEBRIS CLOUD OVER MUCH OF THE AREA...REMNANTS OF THE DECAYING CONVECTIVE ACTIVITY...SO HAVE BACKED OFF ON MAX TEMPS BY A FEW DEGREES EAST OF A LINE FROM DIXON TO GIBSON CITY...WHICH COINCIDES WITH THE ELEVATED BAROCLINIC ZONE. SO...WILL GO WITH HIGHS ARND 83-85F. THERE IS STILL THE POTENTIAL FOR THE FAR SOUTHWESTERN PORTIONS OF THE CWA TO SEE TEMPS IN THE UPPER 80S TO NEAR 90F AS THAT PORTION OF THE CWA LIES SOUTH OF THE MAIN BAROCLINIC ZONE AND THERE SHOULD BE LESS CLOUD COVER AND MORE OPPORTUNITY FOR TEMPS TO CLIMB A LITTLE HIGHER. LATEST THINKING IS THAT THE BEST OPPORTUNITY FOR MORE ORGANIZED CONVECTION...INCLUDING THE CHANCE FOR LOCALLY HEAVY RAINFALL...WILL BE DURG THE LATE EVENING THROUGH THE OVERNIGHT HOURS. THE MODELS ARE KEYING ON A SHORTWAVE CURRENTLY OVER KANSAS AND NEBRASKA TO RIDE UP THE NWRN SIDE OF THE RIDGE THURSDAY AFTERNOON...OVERTOP THE RIDGE EARLY THURSDAY EVENING AND THEN DIVE SOUTHEAST ACROSS NRN IL/IN LATE THURSDAY EVENING AND OVERNIGHT THURSDAY NIGHT. FOLLOWING THIS TREND...HAVE GONE WITH CATEGORICAL POPS OVER THE NRN PORTIONS OF THE CWA THIS EVENING AND LIKELY POPS FOR MUCH OF THE AREA FOR THE PERIOD FROM 00Z-12Z FRIDAY. THE THREAT FOR LOCALLY HEAVY RAINFALL IS STILL PRESENT AS PWATS WILL BE SLIGHTLY IN EXCESS OF 2 INCHES. HOWEVER...DO NOT EXPECT A WIDESPREAD FLOOD THREAT AS THUNDERSTORMS SHOULD BE PROGRESSIVE...BUT LOCALLY HEAVY RAINFALL COULD CAUSE SOME URBAN AND SMALL STREAM TYPE FLOODING ISSUES. KREIN FRIDAY THROUGH SUNDAY... MAIN FOCUS WILL BE ON CONVECTIVE CHANCES...WHICH WILL ALSO PLAY A PIVOTAL ROLE ON TEMPS/HEAT INDEX VALUES FOR THE FRI-SUN STRETCH. GUIDANCE CONTINUES TO FAVOR A SLIGHT FLATTENING IN THE MID-LVL RIDGE FRI...WHICH COULD SETUP THE ATMOSPHERIC RIVER OVER THE CWFA ORIENTED FROM IOWA EAST THROUGH SOUTHERN WISC/NORTHERN IL...STRETCHING EAST INTO NORTHERN IN. THE LOCAL ARW8KM HAS CONTINUED TO BE A LITTLE LESS EXCITED THAN SREF/NAM...HOWEVER THE THEME DOES APPEAR TO BE CONSISTENT. CONFIDENCE HAS DIMINISHED A LITTLE FOR FRI...BUT HAVE ONLY MADE MINOR ADJUSTMENTS TO THE GOING FORECAST. IF LESS CONVECTION/CLOUDS ARE PRESENT FRI...THEN TEMPS SHUD EASILY WARM TO THE UPR 80S/ARND 90 WITH HEAT INDEX VALUES ARND 100 FOR MANY LOCATIONS. PERHAPS EVEN THE LOW 100S SOUTH OF I-80. THE FIRST WAVE OF ACTIVITY SHUD BE MAINLY IN THE MORNING HOURS...SLIDING EAST/SOUTHEAST. THEN THE THETA-E RIDGE LIFTS NORTH INTO IOWA...WITH ANOTHER LOBE OF VORTICITY POISED TO RIDE ALONG THIS FEATURE AND SLIDE SOUTHEAST ACROSS THE FORECAST AREA LATE FRI/EARLY SAT. OVER THE NEXT SEVERAL DAYS...SAT IS LIKELY THE MOST CHALLENGING. AT THIS TIME GUIDANCE HAS COME INTO BETTER AGREEMENT THAT THE FRONTAL BOUNDARY WILL SLIDE BACK SOUTH ACROSS THE FORECAST AREA...ALLOWING LLVL FLOW TO TURN NORTHEAST/EASTERLY WITH CLOUDS LINGERING MUCH OF THE DAY. WITH THIS SCENARIO...SAT WILL LIKELY SEE TEMPS GENERALLY IN THE MID/UPR 80S BUT COULD BE SLIGHTLY LOWER DEPENDING ON HOW THICK CLOUD COVER WILL BE. FORTUNATELY THIS WILL KEEP HEAT INDEX VALUES BELOW 95 DEG FOR MUCH OF THE AREA. THEN PROGRESSING TOWARDS THE SECOND HALF OF THE WEEKEND AND SUN STILL IS ON TRACK TO BE THE WARMEST DAY OF THE STRETCH. THE MID-LVL RIDGE REMAINS POISED TO BUILD BACK INTO THE REGION...LIFTING THE WARM FRONTAL BOUNDARY NORTH OF THE FORECAST AREA SUN. THIS SHUD KEEP MOST OF THE CONVECTIVE CHANCES DISPLACED NORTH. SOUNDINGS SUGGEST THE MID-LVLS WILL BE MUCH WARMER AS WELL...WHICH COULD BE ENOUGH TO EITHER LIMIT OR CAP THE ENVIRONMENT FROM SEEING CONVECTION DEVELOP SUN. HAVE HEDGED POPS IN THIS DIRECTION...WITH A DRY FORECAST ACROSS MUCH OF THE FORECAST AREA SUN. SFC TEMPS SHUD EASILY WARM...WITH HIGHS ARND 90 TO POSSIBLY THE LOW 90S. HOWEVER...LLVL MOISTURE WILL REMAIN HIGH AS WELL WITH DEW PTS IN THE 72-74 DEG RANGE. THE COMBINATION WILL LIKELY PRODUCE HEAT INDEX VALUES IN THE UPR 90S TO PERHAPS AS HIGH AS 105 SUN AFTN FOR AREAS SOUTH OF I-80. MONDAY THROUGH WEDNESDAY... GUIDANCE HAS CONTINUED TO BE LESS EXCITED ABOUT DEPARTING OR WEAKENING THE MID-LVL RIDGE VERY EARLY NEXT WEEK. AS A RESULT MON AND PERHAPS TUE LOOK TO MAINTAIN THE HEAT. FORTUNATELY LLVL MOISTURE DOES APPEAR TO BE A LITTLE LESS THAN THE PRIOR WEEKEND...HOWEVER HEAT INDEX VALUES ARE STILL PROGGED MON TO REACH THE MID TO PERHAPS UPR 90S. LLVL MOISTURE BEGINS TO DECLINE FURTHER FOR TUE...WHICH COULD KEEP TEMPS GENERALLY IN THE MID/UPR 80S. THROUGHOUT THE FIRST HALF OF NEXT WEEK PERIODIC CHANCES FOR CONVECTION REMAIN. THE FINAL FEW PERIODS ENSEMBLES HAVE THE IDEA THAT SOME WEAKENING TO THE ROBUST RIDGE WILL OCCUR. BEACHLER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * TIMING ADDITIONAL THUNDERSTORM CHANCES TODAY...WITH LOW CHANCES THIS AFTERNOON...AND BETTER CHANCES THIS EVENING AND OVERNIGHT. * SWLY WINDS GUSTING UP TO 20KT IN THE AFTERNOON. KMD //DISCUSSION...UPDATED 12Z.. PRIMARY FORECAST CONCERN WILL REMAIN THE CHANCES FOR THUNDERSTORMS OVER THE AREA. AT ISSUANCE TIME...WIDESPREAD SHOWERS AND THUNDERSTORMS COVER NRN IL/NWRN IN. THIS ACTIVITY IS DEVELOPING ALONG AN ELEVATED WARM FRONT WITH INDIVIDUAL CELLS TRACKING TO THE SOUTHEAST UNDER NWLY FLOW ARND 30KT ALOFT. THE WHOLE AREA OF PCPN IS SLOWLY TRANSLATING TO THE EAST AS AN UPPER RIDGE BUILDS OVER THE MIDDLE/UPPER MISSISSIPPI VALLEY...SO THUNDERSTORMS SHOULD IMPACT THE TERMINALS THROUGH THE MORNING. HAVE GONE WITH PREVAILING THUNDER RIGHT OUT OF THE GATE AND ADJUSTED THE INITIAL TEMPO GROUP MORE TO COVER THE POSSIBILITY FOR PERIODS OF MVFR CIGS/VIS UNDER THE PCPN SHIELD. TIMING OF BREAKS IN THE ACTIVITY TODAY IS DIFFICULT AS THE MAIN BAROCLINIC ZONE WILL REMAIN IN PLACE ALOFT THROUGH THE DAY. LATEST HIGH RES MODEL GUIDANCE SUGGESTS THAT THE BEST OPPORTUNITY FOR A LULL IN THE ACTIVITY WILL BE DURG THE AFTERNOON HOURS WHEN WEAK SHORTWAVE RIDGING MOVES OVER THE REGION. THERE SHOULD BE ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A SHORTWAVE CURRENTLY MOVING THROUGH ERN NEBRASKA. ANTICIPATE THAT THIS SHORTWAVE SHOULD TRAVERSE THE REGION BY LATE THIS EVENING GENERATING MORE SHRA/TSRA OVERNIGHT TONIGHT. THERE IS ALSO THE POSSIBILITY THAT THIS SHORTWAVE COULD PHASE WITH THE SHORTWAVE MOVING THROUGH MINNESOTA AND IF THAT HAPPENS...THE COVERAGE OF SHRA/TSRA COULD BE MORE EXTENSIVE FOR A LONGER PERIOD OF TIME. THE SHRA/TSRA POTENTIAL SHOULD COME TO AN END BY EARLY TOMORROW MORNING AS THE UPPER RIDGE BUILDS EAST ACROSS IL/WI/THE WESTERN GREAT LAKES REGION. AS PCPN ENDS...THERE COULD BE A PERIOD OF LINGERING MVFR CIGS/VIS INTO LATE FRIDAY MORNING. KREIN //ORD AND MDW CONFIDENCE...UPDATED 16Z... * HIGH IN SHOWERS THIS AFTERNOON...LOW-MEDIUM IN NO THUNDER OR THIS AFTERNOON. LOW-MEDIUM IN THUNDER CHANCES AND TIMING TONIGHT. * LOW-MEDIUM IN WIND SPEEDS THIS AFTERNOON...HIGH IN DIRECTION EXCEPT AROUND SHOWERS. KMD //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... * FRIDAY NIGHT THROUGH WEDNESDAY...PERIODIC CHANCES FOR TSRA/SHRA WITH OCNL MVFR CIGS/VIS. KREIN && .MARINE... 310 AM CDT NOT MUCH IN THE WAY OF A GRADIENT FOR THE NEXT SEVERAL DAYS...WITH WEAK SYSTEMS EXPECTED. HIGH PRESSURE OVER QUEBEC AND A SERIES OF WEAK TROUGHS OVER THE NORTHERN PLAINS. THERE WILL BE A QUASI- STATIONARY FRONTAL BOUNDARY THAT WILL MEANDER NORTH AND SOUTH ACROSS LAKE MICHIGAN...ALLOWING WINDS TO CHANGE DIRECTION BUT STILL NOT EXPECTING MUCH OF A WIND GRADIENT TO DEVELOP. THE HIGHEST WINDS WILL LIKELY BE ASSOCIATED WITH ANY THUNDERSTORMS THAT CAN PRODUCE BRIEF GUSTS. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1126 AM CDT THU AUG 21 2014 .MESOSCALE DISCUSSION...815 AM CDT THE FORECAST HAS BEEN UPDATED TO RAISE POPS AND QPF IN EASTERN AREAS THIS MORNING AS WELL AS ADJUST HOURLY FORECAST TRENDS OF OTHER ELEMENTS. A SHORT WAVE CENTER OVER NORTH CENTRAL IL IS MOVING ALONG THE ELEVATED WARM AIR ADVECTION PATTERN. FORCING AHEAD OF THIS WITHIN HIGH PWAT AIR /1.82 INCHES ON 12Z DVN RAOB/ HAS LED TO SOME EFFICIENT RAINFALL RATES. MUCH OF THE THUNDERSTORM ACTIVITY HAS BEEN PROGRESSIVE WITH JUST NUISANCE TYPE FLOODING REPORTS. THIS WAVE SHOULD EXIT THE EASTERN FORECAST AREA BY 10 AM. CONTINUED WARM AIR ADVECTION MAY SUPPORT SCATTERED STORMS ACROSS MAINLY NORTHERN IL LATE THIS MORNING ALTHOUGH WITH THE VEERED LOW-LEVEL JET PER PROFILERS AND THE 12Z DVN RAOB...ORGANIZATION OR MAJOR INTENSIFICATION IS NOT ANTICIPATED. SUCH SCATTERED ACTIVITY HAS ALREADY BEEN SEEN ACROSS FAR NORTHWEST IL AND SOUTHWEST WI. THERE HAS BEEN WARMING OF CLOUD TOPS ON IR WITH THESE STORMS. THE LOW-LEVEL FRONTAL ZONE IS DRAPED OUT FROM WEST TO EAST ACROSS THE FORECAST AREA. IT IS TOUGH TO SAY WHERE FOR CERTAIN BUT LOOKS LIKE IT HAS BEEN CONVECTIVELY DISRUPTED FROM ITS EARLIER NORTH PLACEMENT. THIS SHOULD BEGIN TO SHIFT SLOWLY BACK NORTH BY EARLY AFTERNOON BUT WILL BE AN IMPORTANT FEATURE FOR PLACEMENT/MORPHOLOGY OF ANY AFTERNOON AND EVENING CONVECTION. MTF && .DISCUSSION... 330 AM CDT SHORT TERM...THROUGH THURSDAY NIGHT... FOR THE REMAINDER OF THE OVERNIGHT HOURS...AN AREA OF SHOWERS AND THUNDERSTORMS HAS DEVELOPED ALONG AN ELEVATED BAROCLINIC ZONE...NORTH OF A WARM FRONT THAT EXTENDS FROM LOW PRESSURE OVER SOUTH DAKOTA THROUGH CNTRL IL. THE THE CELL MOTION OF THESE STORMS IS TO THE SOUTHEAST AS UPPER RIDGING BUILDS OVER THE UPPER MISSISSIPPI VALLEY AND AN UPPER LOW SITE OVER GEORGIAN BAY. THE RIDGE AXIS SHOULD REMAIN IN PLACE ALONG THE MISSISSIPPI RIVER...SO FLOW ALOFT SHOULD REMAIN GENERALLY NWLY. EXPECT THAT PCPN COVERAGE THROUGH THE REMAINDER OF THE NIGHT SHOULD REMAIN GENERALLY SCATTERED OR IN SHORT LINES. WITH DAYTIME WARMING...ANTICIPATE THAT THE TSRA COVERAGE SHOULD INCREASE...BUT REMAIN FOCUSED ALONG THE ELEVATED BAROCLINIC ZONE WHICH SHOULD REMAIN OVER NRN IL/NWRN IN. WHILE THE SHORT RANGE MODELS HAVE NOT REALLY HANDLED THE CONVECTIVE TRENDS ALL THAT WELL OVER RECENT RUNS...THE LATEST HIGH RES GUIDANCE SUGGESTS THAT THERE COULD BE A LULL IN THE ACTIVITY DURG THE AFTERNOON HOURS WITH SOME WEAK SHORT WAVE RIDGING MOVING OVER THE REGION. HAVE MADE SOME ADJUSTMENT TO THE MAX TEMPS FOR TODAY AS WELL. EXPECT THAT THERE SHOULD BE MORE EXTENSIVE DEBRIS CLOUD OVER MUCH OF THE AREA...REMNANTS OF THE DECAYING CONVECTIVE ACTIVITY...SO HAVE BACKED OFF ON MAX TEMPS BY A FEW DEGREES EAST OF A LINE FROM DIXON TO GIBSON CITY...WHICH COINCIDES WITH THE ELEVATED BAROCLINIC ZONE. SO...WILL GO WITH HIGHS ARND 83-85F. THERE IS STILL THE POTENTIAL FOR THE FAR SOUTHWESTERN PORTIONS OF THE CWA TO SEE TEMPS IN THE UPPER 80S TO NEAR 90F AS THAT PORTION OF THE CWA LIES SOUTH OF THE MAIN BAROCLINIC ZONE AND THERE SHOULD BE LESS CLOUD COVER AND MORE OPPORTUNITY FOR TEMPS TO CLIMB A LITTLE HIGHER. LATEST THINKING IS THAT THE BEST OPPORTUNITY FOR MORE ORGANIZED CONVECTION...INCLUDING THE CHANCE FOR LOCALLY HEAVY RAINFALL...WILL BE DURG THE LATE EVENING THROUGH THE OVERNIGHT HOURS. THE MODELS ARE KEYING ON A SHORTWAVE CURRENTLY OVER KANSAS AND NEBRASKA TO RIDE UP THE NWRN SIDE OF THE RIDGE THURSDAY AFTERNOON...OVERTOP THE RIDGE EARLY THURSDAY EVENING AND THEN DIVE SOUTHEAST ACROSS NRN IL/IN LATE THURSDAY EVENING AND OVERNIGHT THURSDAY NIGHT. FOLLOWING THIS TREND...HAVE GONE WITH CATEGORICAL POPS OVER THE NRN PORTIONS OF THE CWA THIS EVENING AND LIKELY POPS FOR MUCH OF THE AREA FOR THE PERIOD FROM 00Z-12Z FRIDAY. THE THREAT FOR LOCALLY HEAVY RAINFALL IS STILL PRESENT AS PWATS WILL BE SLIGHTLY IN EXCESS OF 2 INCHES. HOWEVER...DO NOT EXPECT A WIDESPREAD FLOOD THREAT AS THUNDERSTORMS SHOULD BE PROGRESSIVE...BUT LOCALLY HEAVY RAINFALL COULD CAUSE SOME URBAN AND SMALL STREAM TYPE FLOODING ISSUES. KREIN FRIDAY THROUGH SUNDAY... MAIN FOCUS WILL BE ON CONVECTIVE CHANCES...WHICH WILL ALSO PLAY A PIVOTAL ROLE ON TEMPS/HEAT INDEX VALUES FOR THE FRI-SUN STRETCH. GUIDANCE CONTINUES TO FAVOR A SLIGHT FLATTENING IN THE MID-LVL RIDGE FRI...WHICH COULD SETUP THE ATMOSPHERIC RIVER OVER THE CWFA ORIENTED FROM IOWA EAST THROUGH SOUTHERN WISC/NORTHERN IL...STRETCHING EAST INTO NORTHERN IN. THE LOCAL ARW8KM HAS CONTINUED TO BE A LITTLE LESS EXCITED THAN SREF/NAM...HOWEVER THE THEME DOES APPEAR TO BE CONSISTENT. CONFIDENCE HAS DIMINISHED A LITTLE FOR FRI...BUT HAVE ONLY MADE MINOR ADJUSTMENTS TO THE GOING FORECAST. IF LESS CONVECTION/CLOUDS ARE PRESENT FRI...THEN TEMPS SHUD EASILY WARM TO THE UPR 80S/ARND 90 WITH HEAT INDEX VALUES ARND 100 FOR MANY LOCATIONS. PERHAPS EVEN THE LOW 100S SOUTH OF I-80. THE FIRST WAVE OF ACTIVITY SHUD BE MAINLY IN THE MORNING HOURS...SLIDING EAST/SOUTHEAST. THEN THE THETA-E RIDGE LIFTS NORTH INTO IOWA...WITH ANOTHER LOBE OF VORTICITY POISED TO RIDE ALONG THIS FEATURE AND SLIDE SOUTHEAST ACROSS THE FORECAST AREA LATE FRI/EARLY SAT. OVER THE NEXT SEVERAL DAYS...SAT IS LIKELY THE MOST CHALLENGING. AT THIS TIME GUIDANCE HAS COME INTO BETTER AGREEMENT THAT THE FRONTAL BOUNDARY WILL SLIDE BACK SOUTH ACROSS THE FORECAST AREA...ALLOWING LLVL FLOW TO TURN NORTHEAST/EASTERLY WITH CLOUDS LINGERING MUCH OF THE DAY. WITH THIS SCENARIO...SAT WILL LIKELY SEE TEMPS GENERALLY IN THE MID/UPR 80S BUT COULD BE SLIGHTLY LOWER DEPENDING ON HOW THICK CLOUD COVER WILL BE. FORTUNATELY THIS WILL KEEP HEAT INDEX VALUES BELOW 95 DEG FOR MUCH OF THE AREA. THEN PROGRESSING TOWARDS THE SECOND HALF OF THE WEEKEND AND SUN STILL IS ON TRACK TO BE THE WARMEST DAY OF THE STRETCH. THE MID-LVL RIDGE REMAINS POISED TO BUILD BACK INTO THE REGION...LIFTING THE WARM FRONTAL BOUNDARY NORTH OF THE FORECAST AREA SUN. THIS SHUD KEEP MOST OF THE CONVECTIVE CHANCES DISPLACED NORTH. SOUNDINGS SUGGEST THE MID-LVLS WILL BE MUCH WARMER AS WELL...WHICH COULD BE ENOUGH TO EITHER LIMIT OR CAP THE ENVIRONMENT FROM SEEING CONVECTION DEVELOP SUN. HAVE HEDGED POPS IN THIS DIRECTION...WITH A DRY FORECAST ACROSS MUCH OF THE FORECAST AREA SUN. SFC TEMPS SHUD EASILY WARM...WITH HIGHS ARND 90 TO POSSIBLY THE LOW 90S. HOWEVER...LLVL MOISTURE WILL REMAIN HIGH AS WELL WITH DEW PTS IN THE 72-74 DEG RANGE. THE COMBINATION WILL LIKELY PRODUCE HEAT INDEX VALUES IN THE UPR 90S TO PERHAPS AS HIGH AS 105 SUN AFTN FOR AREAS SOUTH OF I-80. MONDAY THROUGH WEDNESDAY... GUIDANCE HAS CONTINUED TO BE LESS EXCITED ABOUT DEPARTING OR WEAKENING THE MID-LVL RIDGE VERY EARLY NEXT WEEK. AS A RESULT MON AND PERHAPS TUE LOOK TO MAINTAIN THE HEAT. FORTUNATELY LLVL MOISTURE DOES APPEAR TO BE A LITTLE LESS THAN THE PRIOR WEEKEND...HOWEVER HEAT INDEX VALUES ARE STILL PROGGED MON TO REACH THE MID TO PERHAPS UPR 90S. LLVL MOISTURE BEGINS TO DECLINE FURTHER FOR TUE...WHICH COULD KEEP TEMPS GENERALLY IN THE MID/UPR 80S. THROUGHOUT THE FIRST HALF OF NEXT WEEK PERIODIC CHANCES FOR CONVECTION REMAIN. THE FINAL FEW PERIODS ENSEMBLES HAVE THE IDEA THAT SOME WEAKENING TO THE ROBUST RIDGE WILL OCCUR. BEACHLER && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * TIMING ADDITIONAL THUNDERSTORM CHANCES TODAY...WITH LOW CHANCES THIS AFTERNOON...AND BETTER CHANCES THIS EVENING AND OVERNIGHT. * SWLY WINDS GUSTING UP TO 20KT IN THE AFTERNOON. KMD //DISCUSSION...UPDATED 12Z.. PRIMARY FORECAST CONCERN WILL REMAIN THE CHANCES FOR THUNDERSTORMS OVER THE AREA. AT ISSUANCE TIME...WIDESPREAD SHOWERS AND THUNDERSTORMS COVER NRN IL/NWRN IN. THIS ACTIVITY IS DEVELOPING ALONG AN ELEVATED WARM FRONT WITH INDIVIDUAL CELLS TRACKING TO THE SOUTHEAST UNDER NWLY FLOW ARND 30KT ALOFT. THE WHOLE AREA OF PCPN IS SLOWLY TRANSLATING TO THE EAST AS AN UPPER RIDGE BUILDS OVER THE MIDDLE/UPPER MISSISSIPPI VALLEY...SO THUNDERSTORMS SHOULD IMPACT THE TERMINALS THROUGH THE MORNING. HAVE GONE WITH PREVAILING THUNDER RIGHT OUT OF THE GATE AND ADJUSTED THE INITIAL TEMPO GROUP MORE TO COVER THE POSSIBILITY FOR PERIODS OF MVFR CIGS/VIS UNDER THE PCPN SHIELD. TIMING OF BREAKS IN THE ACTIVITY TODAY IS DIFFICULT AS THE MAIN BAROCLINIC ZONE WILL REMAIN IN PLACE ALOFT THROUGH THE DAY. LATEST HIGH RES MODEL GUIDANCE SUGGESTS THAT THE BEST OPPORTUNITY FOR A LULL IN THE ACTIVITY WILL BE DURG THE AFTERNOON HOURS WHEN WEAK SHORTWAVE RIDGING MOVES OVER THE REGION. THERE SHOULD BE ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A SHORTWAVE CURRENTLY MOVING THROUGH ERN NEBRASKA. ANTICIPATE THAT THIS SHORTWAVE SHOULD TRAVERSE THE REGION BY LATE THIS EVENING GENERATING MORE SHRA/TSRA OVERNIGHT TONIGHT. THERE IS ALSO THE POSSIBILITY THAT THIS SHORTWAVE COULD PHASE WITH THE SHORTWAVE MOVING THROUGH MINNESOTA AND IF THAT HAPPENS...THE COVERAGE OF SHRA/TSRA COULD BE MORE EXTENSIVE FOR A LONGER PERIOD OF TIME. THE SHRA/TSRA POTENTIAL SHOULD COME TO AN END BY EARLY TOMORROW MORNING AS THE UPPER RIDGE BUILDS EAST ACROSS IL/WI/THE WESTERN GREAT LAKES REGION. AS PCPN ENDS...THERE COULD BE A PERIOD OF LINGERING MVFR CIGS/VIS INTO LATE FRIDAY MORNING. KREIN //ORD AND MDW CONFIDENCE...UPDATED 16Z... * HIGH IN SHOWERS THIS AFTERNOON...LOW-MEDIUM IN NO THUNDER OR THIS AFTERNOON. LOW-MEDIUM IN THUNDER CHANCES AND TIMING TONIGHT. * LOW-MEDIUM IN WIND SPEEDS THIS AFTERNOON...HIGH IN DIRECTION EXCEPT AROUND SHOWERS. KMD //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... * FRIDAY NIGHT THROUGH WEDNESDAY...PERIODIC CHANCES FOR TSRA/SHRA WITH OCNL MVFR CIGS/VIS. KREIN && .MARINE... 310 AM CDT NOT MUCH IN THE WAY OF A GRADIENT FOR THE NEXT SEVERAL DAYS...WITH WEAK SYSTEMS EXPECTED. HIGH PRESSURE OVER QUEBEC AND A SERIES OF WEAK TROUGHS OVER THE NORTHERN PLAINS. THERE WILL BE A QUASI- STATIONARY FRONTAL BOUNDARY THAT WILL MEANDER NORTH AND SOUTH ACROSS LAKE MICHIGAN...ALLOWING WINDS TO CHANGE DIRECTION BUT STILL NOT EXPECTING MUCH OF A WIND GRADIENT TO DEVELOP. THE HIGHEST WINDS WILL LIKELY BE ASSOCIATED WITH ANY THUNDERSTORMS THAT CAN PRODUCE BRIEF GUSTS. BEACHLER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 1015 AM CDT Thu Aug 21 2014 .UPDATE... ISSUED AT 1015 AM CDT THU AUG 21 2014 15z/10am surface analysis shows warm front extending from northern Iowa to southern Lake Michigan. Numerous showers and thunderstorms have been tracking along this boundary early this morning, mainly impacting locations along/north of the I-80 corridor. This is a bit further north than previously forecast, thanks to the upper ridge building across the region. 12z NAM keeps central Illinois dry throughout the day, then develops nocturnal convection as far south as the I-72 corridor late tonight. NAM was too aggressive with the southward extent of precip last night, so am skeptical of its latest solution. HRRR is also dry through the day, and does not develop any convection across the area through 03z this evening. Based on latest satellite/radar trends and NAM/HRRR data, have trimmed PoPs today and tonight. Will maintain slight chance for showers/thunder across the far N and E CWA through the morning, then will go with dry conditions across the board this afternoon. Have also reduced PoPs for tonight, focusing highest chances across the north from the Peoria and Bloomington areas northward after midnight. With a good deal of sunshine and southwesterly winds, afternoon highs will reach the upper 80s and lower 90s. && .SHORT TERM...(Today and Tonight) ISSUED AT 342 AM CDT THU AUG 21 2014 Warm front has lifted north through most of the area and based on surface observations, looks to be just north of I-74 at this point. Believe the front will continue to lift north through the day, resulting in the whole CWA being in the warm sector for the end of the week. However, the mid level ridge will be somewhat flat and any disturbance or wave that moves along the top of the ridge could result in precip dropping into the northern and northeastern part of the CWA. So chance pops will continue to be warranted over parts of the CWA today and tonight. Pops will be less during the daytime hours but then increase over the northeastern half of the CWA for the overnight hours, tonight. Temperatures will be warm today, but cloud cover could keep afternoon highs from getting too high, though still expecting highs around 90 today. Lows tonight will be similar to now, just about 1-2 degrees warmer. && .LONG TERM...(Friday through Wednesday) ISSUED AT 342 AM CDT THU AUG 21 2014 Summer heat continues through the remains of the weekend. Hot and humid conditions lending to an isolated thunderstorm threat through the weekend, particularly towards the NE as waves push over the upper ridge building into the Midwest. Models shifting with each issuance as to the actual increased threat with the erosion of the ridging to the NE. Heat and humidity has been more consistent, though even that has seen some shifts, starting to retract some of the eastward creep of the 850 mb temps. Not pulling back too much in the way of guidance just yet and temps Fri-Sun still in the 90s, heat indices over 100F. Issuance of a Heat Advisory covered above...however, should the dwpts materialize, or see the temps respond as expected behind this mornings warm front today... will rethink the issuance of a Heat Advisory for the weekend as these temps are not only well above normal, but more impactful after such a mild summer so far. Into the extended, day 6/just into day 8, models have gone back to a divergence in solutions as the GFS is more progressive with the next upper trof moving a cold front through with storms and cooler temps in the wake...while the 00Z ECMWF is now cutting off the low over the NW, extending the ridges hold over the region. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) ISSUED AT 626 AM CDT THU AUG 21 2014 The warm front has lifted north of all the TAF sites and all pcpn has moved north or east of the sites this morning. So most of the day all sites will be pcpn free. So, there will be some high CU/SC today with some cirrus early and then maybe some AC later this morning. Then by this afternoon, skies should become scattered. Clouds will then be on the increase around midnight as a complex of storms will develop west of the area and move along the warm front tonight. This should bring broken AC clouds to SPI and DEC, but VCTS and broken SC/CU at PIA/BMI/CMI. Winds will be southwest, but become southerly this evening for a brief time, then back to southwest around midnight. Wind speeds will be around 7-10kts through the period. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...BARNES SHORT TERM...AUTEN LONG TERM...HJS AVIATION...AUTEN
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
135 AM CDT THU AUG 21 2014 .DISCUSSION... 819 PM CDT FOR EVENING UPDATE... HAVE MADE SOME FAIRLY SIGNIFICANT UPDATES TO SHOWER/THUNDERSTORM POPS AND TIMING OVERNIGHT...BASED ON OBSERVATIONAL DATA AND HIGH RES MODEL TRENDS OVER THE PAST SEVERAL HOURS. OVERALL...HAVE TRIMMED BACK POPS TO ISOLATED/SCATTERED SHOWERS THROUGH THE REMAINDER OF THIS EVENING...WITH GRADUAL INCREASE IN SCATTERED SHOWER/THUNDERSTORM COVERAGE AFTER MIDNIGHT...BUT WITH GREATEST POTENTIAL LOOKING LIKE THURSDAY MORNING WITH EXPECTED MCS REMNANTS ARRIVING FROM MINNESOTA. A STATIONARY FRONT STRETCHES FROM SOUTH DAKOTA SOUTHEAST ACROSS NORTHERN MISSOURI AND INTO THE LOWER OHIO VALLEY THIS EVENING. NORTH OF THE SURFACE BOUNDARY...AN AREA OF CLOUDS AND ISOLATED SHOWERS HAS PERSISTED WITHIN THE ELEVATED BAROCLINIC ZONE...WITH A COUPLE OF WEAK SHORT WAVES NOTED TOPPING MID-LEVEL SHORT WAVE RIDGE AXIS WHICH WAS ROUGHLY FROM ST LOUIS NORTHWEST INTO SOUTHWEST MINNESOTA. MODEL GUIDANCE HAS BEEN VERY INSISTENT IN DEVELOPING STRONG CONVECTION ALONG THIS ELEVATED BAROCLINIC ZONE THIS EVENING INTO EARLY THURSDAY MORNING...THOUGH COMPARISON TO OBSERVED RADAR/SATELLITE DATA SUGGESTS GUIDANCE HAS BEEN OVER FORECASTING EXTENSIVE COVERAGE OF DEEP CONVECTION SO FAR. WITH THE BEST LOW LEVEL JET FLOW AND SHORT WAVE FORCING CURRENTLY ACROSS THE PLAINS AND ORIENTED INTO THE MID-MISSOURI VALLEY REGION...WOULD ANTICIPATE THE BEST AREA FOR STRONG CONVECTION TO DEVELOP OVER THE NEXT FEW HOURS WOULD BE FROM NORTHEAST NEBRASKA/SOUTHEAST SOUTH DAKOTA INTO WESTERN MINNESOTA/NORTHWEST IOWA. WEAKER FORCING AND WEAKER WEST-SOUTHWEST LOW LEVEL FLOW INTO BAROCLINIC ZONE EAST OF THE MISSISSIPPI...WHICH SUGGESTS LESS INTENSIVE DEVELOPMENT HERE. DEVELOPMENT STILL EXPECTED ACROSS THE AREA DURING THE NIGHT AS THE LOW LEVEL WEST-SOUTHWESTERLY FLOW STRENGTHENS A BIT...THOUGH CONFIDENCE IS FAIRLY LOW ON AMOUNT OF COVERAGE. HRRR HAS CONSISTENTLY SHOWN THE SCENARIO OF AN MCS DEVELOPING OUT OF ANTICIPATED CONVECTION OVER THE PREVIOUSLY MENTIONED MID-UPPER MISSOURI VALLEY REGION OVERNIGHT...WHICH WOULD APPROACH THE FORECAST AREA FROM THE NORTHWEST TOWARD MORNING. WITH ALL OF THIS IN MIND...HAVE TRIMMED BACK POPS OVERNIGHT AND ESPECIALLY THIS EVENING...GRADUALLY INCREASING CHANCES AFTER MIDNIGHT. MAINTAINED LIKELY POPS THURSDAY MORNING...WITH MCS REMNANTS EXPECTED TO PERHAPS PRESENT THE GREATEST RAINFALL PROBABILITY. 00Z SOUNDINGS UPSTREAM OF OUR FORECAST AREA DEPICT PWATS IN THE 1.5-1.6 INCH RANGE SO STILL A LOCALLY HEAVY RAINFALL THREAT FROM STRONGER CONVECTION ESPECIALLY DURING THE PRE-DAWN THROUGH MID-MORNING THURSDAY PERIOD. ALSO...WITH CLOUDS AND LIGHT WEST-SOUTHWEST FLOW BUMPED MIN TEMPS JUST A BIT OVERNIGHT. RATZER //PREV DISCUSSION... 320 PM CDT MAIN FORECAST CONCERNS ARE WITH PERSISTENT CHANCES FOR SHOWERS AND THUNDERSTORMS OVER THE NEXT SEVERAL DAYS...WITH SOME POTENTIAL FOR STRONG/SEVERE STORMS BUT WITH HIGHER CONFIDENCE FOR HEAVY RAINFALL. WITH CONFIDENCE STILL LOWER ON COVERAGE AND PLACEMENT OF STORMS TONIGHT...HAVE NOT ISSUED A FLOOD WATCH AT THIS TIME BUT DID ISSUE AN SPS TO RAISE AWARENESS FOR THIS POTENTIAL. IN THE NEAR TERM...QUIETER CONDITIONS ONGOING THIS AFTERNOON WITH THE BULK OF THE CWA DRY. LATEST RADAR IMAGERY DEPICTING STEADY STREAM OF SHOWERS AND THUNDERSTORMS STILL MOVING SOUTHEAST THROUGH EASTERN IOWA AND WEST CENTRAL ILLINOIS...BUT WITH COVERAGE AND INTENSITY DIMINISHING. SHORT TERM GUIDANCE STILL TRYING TO BRING PRECIP ACROSS NORTH/NORTHEAST ILLINOIS LATE THIS AFTERNOON INTO THE EARLY EVENING BUT DONT REALLY AGREE. FEEL THAT CONDITIONS WILL REMAIN DRY THROUGH EARLY THIS EVENING FOR MOST LOCATIONS WITH THE EXCEPTION FOR AREAS ALONG AND SOUTHWEST OF LINE FROM OREGON TO WATSEKA...WHERE STEERING FLOW COULD DRIFT A STRAY SHOWER OR THUNDERSTORM BRIEFLY OVER THAT AREA. ELSEWHERE...BRIEF AND LIGHT RETURNS CONTINUE TO SHOW ON RADAR OVER NORTHEAST ILLINOIS IN AND AROUND WEAK CONVERGENCE ALONG LAKE BREEZE IN FAR SOUTHEAST WISCONSIN AND FAR NORTHEAST ILLINOIS. A LACK OF ANY INHIBITION THIS AFTERNOON AND THIS WEAK CONVERGENCE COULD ALLOW FOR CONTINUED DEVELOPMENT OF THESE LIGHT SHOWERS THIS AFTERNOON. TONIGHT...INCREASING CHANCES FOR SHOWERS/THUNDERSTORMS WILL OCCUR THROUGHOUT THE NIGHT AS UPSTREAM UPPER LEVEL RIDGE CONTINUES TO BUILD ACROSS THE REGION WITH THE RIDGE AXIS SHIFTING EAST TOWARDS THE CWA...AND WHILE SURFACE WARM FRONT SITUATED OVER THE SOUTHERN CWA LIFTS NORTH. UPSTREAM SHORTWAVE ENERGY NOTED ON CURRENT WATER VAPOR IMAGERY WILL RIDE ALONG THIS RIDGE AND MOVE ACROSS THE CWA TONIGHT INTO EARLY THURSDAY MORNING. MEANWHILE...STRENGTHENING LLJ WILL BEGIN VEERING THIS EVENING AND THEN BE ORIENTED TOWARDS THE CWA LATER IN THE NIGHT. THIS WILL ALL PROVIDE FOCUS FOR THUNDERSTORM DEVELOPMENT OVERNIGHT ESPECIALLY AS WAA RAMPS UP WITH THE VEERING/STRENGTHENING LLJ. WEAK TO MODERATE INSTABILITY AXIS WILL BE IN PLACE TONIGHT WITH POTENTIAL FOR SOME STEEPER MID LAPSE RATES...CURRENTLY OBSERVED JUST SOUTH OF THE CWA...TO LINGER TONIGHT. CONFIDENCE IS NOT OVERLY GREAT WITH REGARDS TO THE INTENSITY OF STORMS TONIGHT BUT WITH THE PREVIOUSLY MENTIONED FORCING MECHANISMS COMING TOGETHER OVERHEAD TONIGHT...WOULD EXPECT THE POSSIBILITY FOR AT LEAST AN ISOLATED STRONGER STORM TO PROVIDE A HAIL/WIND THREAT. FEEL THAT THE BEST CHANCES FOR THIS POSSIBILITY COULD OCCUR OVER THE SOUTH/SOUTHWEST HALF OF THE CWA...WHERE THE STEEPER MID LEVEL LAPSE RATES WILL POSSIBLY RESIDE PER CURRENT ANALYSIS AND SREF GUIDANCE. A GROWING CONCERN WILL BE FOR THE POTENTIAL OF HEAVY RAINFALL AND LOCALIZED FLOODING WITH THESE STORMS TONIGHT INTO EARLY THURSDAY. GUIDANCE CONTINUES TO VARY WITH REGARD TO OVERALL COVERAGE AND EXACT PLACEMENT OF BEST DEVELOPMENT TONIGHT...AND WITH MY CONFIDENCE NOT THE GREATEST WITH REGARDS TO RESIDENCE TIME OF ANY STORM. NONETHELESS...OBSERVED HIGH PWAT AXIS OF 1.5 TO 2 INCHES CURRENTLY OBSERVED JUST TO THE SOUTHWEST OF THE CWA WILL SHIFT NORTHEAST OVER THE CWA TONIGHT...AND WITH THIS HIGHEST AXIS EXPECTED TO BE CENTERED OVERHEAD TONIGHT. WITH THESE HIGH PWATS IN PLACE AND WITH SURFACE DEWPOINTS AROUND 70 DEG AND 850MB DEWPOINTS APPROACHING 15-16C...ANY STORM WILL EASILY HAVE THE POTENTIAL TO PRODUCE HEAVY DOWNPOURS. DESPITE THESE CONCERNS...I ONCE AGAIN DONT HAVE THE GREATEST CONFIDENCE OF COVERAGE/PLACEMENT AND HAVE DECIDED TO HOLD OFF ON ANY FLOOD WATCH AT THIS TIME. THIS WILL NEED TO CONTINUE TO BE CLOSELY MONITORED THIS EVENING BUT IN THE NEAR TERM HAVE DECIDED TO ISSUE AN SPS FOR THIS POSSIBILITY. STILL THINK THAT WHAT OCCURRED JUST TO THE WEST/SOUTHWEST TODAY COULD EASILY OCCUR TONIGHT INTO THURSDAY OVER THE CWA...ALTHOUGH WITH THE POSSIBILITY FOR A SLIGHTLY DIFFERENT SETUP PROVIDING BETTER/STRONGER THUNDERSTORM DEVELOPMENT. ANY LINGERING STORMS THURSDAY MORNING WILL SHIFT EAST AND NORTHEAST OF THE CWA THROUGH MID DAY WITH A POSSIBILITY FOR CONTINUED HEAVY RAINFALL. THESE DEPARTING STORMS COULD ALLOW FOR CLEARING SKIES AND THE ENVIRONMENT TO DESTABILIZE ONCE AGAIN DURING MID DAY AND EARLY AFTERNOON...WITH THE POSSIBILITY FOR THUNDERSTORMS TO REDEVELOP ALONG LIFTING FRONTAL BOUNDARY. CLEARING WILL BE KEY WITH POTENTIAL FOR INTENSITY OF THESE STORMS ON THURSDAY BUT WITH STRONG TO SEVERE STORMS POSSIBLE...ESPECIALLY IF A GOOD AMOUNT OF HEATING COULD OCCUR. FOCUS FOR THUNDERSTORMS WILL CONTINUE THURSDAY NIGHT AS WELL...WITH HIGH MOISTURE CONTENT AIR STILL IN PLACE. THIS WILL ALSO CONTINUE CONCERNS FOR HEAVY RAINFALL ACROSS THE AREA. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * PERIODIC CHANCES FOR THUNDERSTORMS THROUGH THE PERIOD. * SWLY WINDS GUSTING UP TO 20KT IN THE AFTERNOON. KREIN //DISCUSSION...UPDATED 06Z.. PRIMARY FORECAST CONCERN WILL REMAIN THE CHANCES FOR THUNDERSTORMS OVER THE AREA. AT ISSUANCE TIME...A LINE OF SHOWERS AND A FEW THUNDERSTORMS WAS DEVELOPING ALONG A NARROW CORRIDOR FROM AROUND RFD TO JUST SOUTH OF MDW AND INTO NWRN INDIANA. THE PCPN IS DEVELOPING ALONG AN ELEVATED WARM FRONT...WITH THE SFC WARM FRONT STILL TO THE SOUTH...EXTENDING FROM LOW PRESSUURE OVER SOUTH DAKOTA SOUTHEAST TO SRN IL. INDIVIDUAL CELLS ARE TRACKING TO THE SOUTHEAST...WITH NWLY FLOW ALOFT...BUT THE AREA OF PCPN IS SLOWLY LIFTING TO THE NORTH. GIVEN THE SOMEWHAT SCATTERED NATURE OF THE PCPN AREA...HAVE ADDED VCSH MENTION BACK TO THE TAFS THROUGH 12Z. HAVE RESISTED THE TEMPTATION TO CALL IS VCTS AS THERE IS LITTLE LIGHTNING ACTIVITY. HOWEVER...TS SHOULD BECOME MORE OF AN ISSUE FOR THE TERMINALS THROUGH THE DAY TOMORROW AS THE WARM FRONT SLOWLY LIFTS TO THE NORTH. THE WARM FRONT SHOULD LIFT THROUGH NRN IL/IN THROUGH THE DAY TOMORROW...PUTTING THE REGION IN THE WARM SECTOR OF THE SYSTEM...WITH PERSISTENT WARM/MOIST ADVECTION. THE ENVIRONMENT SHOULD BECOME INCREASINGLY UNSTABLE THROUGH THE DAY AND ADDITIONAL THUNDERSTORM ACTIVITY IS LIKELY OVER THE AREA...BUT CONFIDENCE REMAINS LOW IN THE EXACT TIMING AND COVERAGE OF THE IMPACTS AT THE TERMINALS. SO...HAVE ONLY GONE WITH A VCTS FOR THE MORNING HOURS...THOUGH CONFIDENCE IS HIGHER THAT THERE SHOULD BE SOME TS AROUND THE AREA. HAVE KEPT THE TAFS DRY FOR THE AFTERNOON HOURS...WITH THE SFC WARM FRONT PUSHING INTO WISCONSIN AND AN ABSENSE OF UPPER LEVEL FORCING...THOUGH THERE STILL COULD BE SOME ISOLD-SCT SHRA/TSRA. THERE SHOULD BE A BETTER CHANCE FOR MORE ORGANIZED CONVECTION THUSDAY NIGHT AS THE MODELS ARE INDICATING A RATHER VIGOROUS SHORTWAVE OVERTOPPING THE UPPER RIDGE OVER THE MISSISSIPPI VALLEY AND TURNING SOUTHEAST ACROSS NRN IL. THIS SHORTWAVE...COINCIDENT WITH THE WARM FRONT WHICH SHOULD BE CLOSE TO THE WISCONSIN BORDER SHOULD PROVIDE BOTH SFC AND UPPER LEVEL FORCING IN AN ALREADY MOIST AND UNSTABLE ENVIRONMENT. SO...HAVE INTRODUCED TEMPO TS FOR THE EVENING HOURS AND A PROB30 FOR THE LATE NIGHT HOURS. AS THE FORECAST PICTURE BECOME A BIT MORE CLEAR...PREVAILING TS TIMING WILL LIKELY BE ADDED IN THE UPDATES LATER TODAY. KREIN //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM TO HIGH CONFIDENCE THAT THERE BE PERIODS OF SHOWERS AND THUNDERSTORMS THROUGH THE FORECAST PERIOD...BUT LOW IN THE TIMING AND COVERAGE. //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... * FRIDAY THROUGH TUESDAY...PERIODIC CHANCES FOR TSRA. KJB && .MARINE... 158 PM CDT FAIRLY LIGHT WIND REGIME IS EXPECTED THROUGH THE WEEKEND WITH WEAK PRESSURE GRADIENT EXPECTED WITH HIGH PRESSURE OVER THE ST LAWRENCE VALLEYS REGION AND A TROUGH OF LOW PRESSURE OVER THE NORTHERN AND CENTRAL PLAINS. A QUASI-STATIONARY WARM FRONT WILL EXTEND EAST FROM THE LOW INTO THE LOWER GREAT LAKES REGION...WITH THE POSITION OF THE WARM FRONT LIKELY BEING MODULATED AT TIMES BY CONVECTIVE COMPLEXES. IZZI && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
155 PM EDT THU AUG 21 2014 .SYNOPSIS... ISSUED AT 154 PM EDT THU AUG 21 2014 SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE REGION WILL BECOME MORE LIKELY TONIGHT AS A COUPLE OF UPPER LEVEL DISTURBANCES APPROACH. HIGHS TODAY WILL BE IN THE LOWER TO MID 80S. LOWS THE NEXT SEVERAL NIGHTS WILL BE AROUND 70. HIGHS THIS WEEKEND WILL BE AROUND 90 DEGREES. && .UPDATE... ISSUED AT 1128 AM EDT THU AUG 21 2014 BROAD ISENTROPIC LIFT/LOW LEVEL MOISTURE TRANSPORT WILL CONTINUE THROUGH THIS AFTERNOON FROM THE MID MS RIVER VALLEY EXTENDING EASTWARD TO THE OHIO RIVER VALLEY. RUC INITIALIZATION SUPPORT CONVECTIVE ENHANCEMENT TO SMALL SCALE VORT MAX TRACKING ACROSS SOUTH/SOUTHEAST PORTIONS OF THE AREA THIS MORNING...WITH SOME INDICATIONS OF MCV HAVING ALSO FORMED ACROSS FAR NORTH CENTRAL INDIANA. A BRIEF LULL IN PRECIP IS POSSIBLE IN WAKE OF THIS FEATURE OVER NEXT FEW HOURS...BUT A STEADY STREAM OF SMALLER SCALE WAVES EMBEDDED IN NORTHWEST UPPER FLOW AND POOLED LOW LEVEL MOISTURE AXIS ACROSS MUCH OF LOCAL AREA WILL SUPPORT AT LEAST CHANCE TSRA MENTION THROUGH THE REMAINDER OF THE AFTERNOON. SLIGHTLY MORE STABLE CONDITIONS ASSOCIATED WITH MORNING CLOUDS/PRECIP MAY TEMPER SEVERE THREAT AT LEAST THROUGH MUCH OF THE AFTERNOON HOURS. POCKET OF STRONGER MID/UPPER FLOW IS EXPECTED TO OVERSPREAD THE AREA THIS EVENING AND THIS MAY SUPPORT SOUTHEAST PROPAGATION OF POTENTIAL CONVECTIVE SYSTEM FORMING UPSTREAM OF LOCAL AREA TONIGHT. RADAR ESTIMATES THAT MANY LOCATIONS FROM WESTERN STARKE COUNTY INTO GRANT COUNTY HAVE EXPERIENCED 1 TO 2 INCHES OF RAINFALL WITH MORNING STORMS...AND SOME HYDRO CONCERNS MAY EVOLVE TONIGHT DEPENDING ON UPSTREAM LATE AFTERNOON/EVENING CONVECTIVE EVOLUTION...BUT WILL HOLD OFF ON ANY HYDRO HEADLINES AT THIS TIME. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 449 AM EDT THU AUG 21 2014 UPPER LEVEL JET DYNAMICS COMBINED WITH THE LEADING EDGE OF THETA E CONVERGENCE WAS HELPING TO TRIGGER ISOLATED STORMS AND AN AREA OF SHOWERS NORTH OF THE FRONT. THE STORMS WERE HIGH BASED EARLY THIS MORNING...BUT SHOULD BECOME MORE SURFACE BASED AS THE FRONT MOVES NORTH AND AS THE ATMOSPHERE DESTABILIZES WITH DAYTIME HEATING LATER TODAY. THETA E FLUX WILL INCREASE TONIGHT...WITH A BETTER CHANCE FOR SHOWERS AND STORMS AS AN UPPER LEVEL DISTURBANCE TOPS THE UPSTREAM RIDGE AND MOVES INTO THE WESTERN GREAT LAKES REGION. THE 12KM NAM APPEARED TO HAVE A REASONABLE HANDLE ON THE TIMING OF THIS UPSTREAM SYSTEM AND THE TRACK OVER THE UPPER LEVEL RIDGE...SO HAVE LIKELY THUNDERSTORM CHANCES LATER TONIGHT. SEVERE STORMS ARE POSSIBLE GIVEN DEEP LAYER SHEAR TOPPING OUT AT 30 TO 40 KNOTS. HAVE RAISED HIGHS TODAY. THE NAM/MET HAS RAISED HIGHS TODAY 5 DEGREES AT SBN AND APPEARS ON TRACK...COMING MORE IN LINE WITH THE GFS/MAV. 850 MB TEMPS WILL BE BETWEEN 18C AND 19C TODAY...AND SOME SUN TODAY SHOULD ALLOW HIGHS TO RISE TO BETWEEN 82F AND 86F. && .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 449 AM EDT THU AUG 21 2014 MAIN CONCERN THIS PERIOD IS POTENTIAL FOR EXCESSIVE HEAT AS STRONG UPR LEVEL RIDGE BUILDS INTO THE AREA RESULTING IN HEAT INDEX READINGS IN THE 90S EACH AFTN. ALTHOUGH THESE READINGS ARE A BIT BLO OUR ADVISORY CRITERIA... IMPACTS MAY BE GREATER THAN USUAL DUE TO EXPECTED RATHER LONG DURATION OF THE HEAT WAVE... AND DIFFICULTY FOR PEOPLE TO BECOME ACCLIMATED TO THE HEAT GIVEN ABNORMALLY COOL TEMPS THUS FAR THIS SUMMER. CONVECTION AT NOSE OF A WK WLY LLJ MAY BE ONGOING IN OUR AREA AT THE START OF THE PERIOD FRIDAY MORNING. WK LOW LEVEL WAA PATTERN AND STNRY SFC BOUNDARY DRAPED ACROSS NERN PORTION OF THE CWA EXPECTED FRI WHICH MAY PROVIDE FOCUS FOR REDEVELOPMENT IN THE AFTN AS AIRMASS DESTABILIZES. THIS BOUNDARY EXPECTED TO REMAIN OVER THE AREA FRI NGT WITH NOSE OF WSWLY LLJ OVER THE MID MS VALLEY PROVIDING FORCING FOR CONVECTION UPSTREAM OVERNIGHT WHICH COULD BE SUSTAINED INTO OUR AREA GIVEN LINGERING WK/MODERATE ELEVATED INSTABILITY. RATHER STRONG NWLY UPR LEVEL FLOW ON EAST SIDE OF MS VALLEY RIDGE WILL PROVIDE DECENT DEEP LAYER SHEAR FRI/FRI NGT...ESPECIALLY OVER ERN PORTIONS OF THE CWA WHICH ALSO COULD AID IN CONVECTIVE PERSISTENCE AS WELL AS SUPPORT A FEW STRONG/SVR STORMS AROUND PEAK HEATING FRI AFTN/EVE. DOUBT CONVECTION WILL BE SUFFICIENTLY WIDESPREAD OR LAST LONG ENOUGH TO HOLD TEMPS DOWN SIGNIFICANTLY FRIDAY. GIVEN H85 TEMPS PROGGED IN THE 19-20C RANGE STAYED CLOSE TO PREVIOUS FCST WITH HIGHS RANGING FROM THE M80S NE TO AROUND 90 SW. DWPTS SHOULD ALSO BE RISING TO THE L-M70S WHICH WILL RESULT IN AFTN HEAT INDICES ABOUT 5-10F HIGHER THAN TEMPS. LIGHT WINDS FRI NGT SHOULD ALLOW FOR SOME RADIATIONAL COOLING SO EXPECT MINS TO BE IN THE U60S NE AND L70S SW. SIMILAR CONDITIONS EXPECTED SATURDAY. UPR RIDGE AXIS SHOULD MOVE SLIGHTLY EAST INTO OUR AREA AS STRONG TROF MOVES ACROSS THE NRN ROCKIES. E-W ORIENTED SURFACE BOUNDARY WILL LIKELY REMAIN OVER THE AREA PROVIDING SOME FOCUS FOR CONVECTION AS AIRMASS DESTABILIZES DURING THE DAY. WK LOW LEVEL GRADIENT WINDS AND VERY MOIST AIRMASS OVER THE AREA SHOULD AGAIN LIMIT HEATING BUT EXPECT SUFFICIENT MIXING TO ALLOW FOR HIGHS CLOSE TO FRIDAYS READINGS AS SUGGESTED BY MAV MOS TEMPS. STNRY SFC BOUNDARY SHOULD LIFT NORTH OF OUR CWA SAT NGT-SUNDAY AS SFC LOW DEEPENS OVER THE NRN PLAINS. THIS SHOULD RESULT IN MAINLY DRY CONDITIONS BY SUNDAY WITH TEMPS CONTG TO SLOWLY WARM. NRN PLAINS LOW EXPECTED TO LIFT NE-E INTO ONTARIO MONDAY AND TO QUEBEC TUE WITH TRAILING WK CDFNT DROPPING SOUTH INTO OUR AREA BY THAT TIME. SOME SUPPRESSION OF UPR RIDGE PER ECMWF SOLUTION SEEMS APPROPRIATE AS SHRTWV BREAKS OVER THE TOP ACROSS THE UPR GRTLKS... SO WKNG CAPPING INVERSION/CHC TSTMS... AND SLIGHTLY LOWER TEMPS FCST BY TUE. MEDIUM RANGE MODELS DIFFERING SOLUTIONS WRT PERSISTENCE OF UPR RIDGE TUE LEADING TO EVEN GREATER DIFFERENCES BY WED WITH ECMWF SUGGESTING RIDGING BUILDING BACK INTO OUR REGION AS CLOSED LOW DEVELOPS IN THE WRN U.S., WHILE GFS FCSTG MORE PROGRESSIVE WRN TROF WITH A STRONG SHRTWV APPROACHING THE MIDWEST BY WED EVE. GIVEN LARGE DIFFERENCES STAYED CLOSE TO PREVIOUS FCST WHICH WAS FOR CONTD SLOW COOLING TREND AND A LOW CHC OF TSTMS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 129 PM EDT THU AUG 21 2014 FIRST WAVE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO EXIT NORTHEAST INDIANA OVER THE NEXT FEW HOURS...WITH ATTENTION FOR REMAINDER OF AFTERNOON AND EVENING TURNING UPSTREAM WITH A COUPLE OF ADDITIONAL SHORT WAVE PROGRESSING THROUGH UPPER RIDGE. SOME LINGERING IFR CONDITIONS WILL PERSIST OVER THE NEXT HOUR OR TWO BEFORE IMPROVING AFTER 20Z. THE NEXT SHORT WAVE ACROSS SOUTHERN WISCONSIN SHOULD ALLOW SHOWERS TO MOVE BACK INTO NORTH CENTRAL INDIANA LATE THIS AFTERNOON. A RELATIVE STABLE BUBBLE PERSISTS ACROSS NORTH CENTRAL INDIANA IN REGARDS TO SFC BASED CONVECTIVE POTENTIAL...BUT SUSPECTING ENOUGH ELEVATED INSTABILITY WILL BE PRESENT FOR SOME THUNDER POTENTIAL AS THE SRN WISCONSIN SHORT WAVE SHIFTS EASTWARD THIS AFTERNOON. BETTER CHANCE OF THUNDER STILL APPEARS TO BE IN STORE FOR LATE EVENING INTO THE OVERNIGHT AS NEXT UPSTREAM IOWA SHORT WAVE APPROACHES THE AREA WITH PERSISTENT ISENTROPIC UPGLIDE ASSOCIATED WITH LOW LEVEL BOUNDARY ACROSS THE REGION. HAVE KEPT IN VCSH MENTION AFTER 12Z WITH A MORE MUDDLED PICTURE AT THIS FORECAST DISTANCE IN TERMS OF LATCHING ONTO ANY SIGNIFICANT ADDITIONAL SHORT WAVES. GRADUALLY MID LEVEL HEIGHT RISES TOWARD THE END OF THE PERIOD SHOULD DIMINISH CONVECTIVE POTENTIAL LATER FRIDAY AFTERNOON. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...MARSILI SYNOPSIS...MARSILI SHORT TERM...SKIPPER LONG TERM...JT AVIATION...MARSILI VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1142 AM EDT THU AUG 21 2014 .SYNOPSIS... ISSUED AT 152 AM EDT THU AUG 21 2014 PERIODIC SHOWERS AND THUNDERSTORMS ARE POSSIBLE INTO FRIDAY AS A WARM FRONT SLOWLY MOVES NORTH INTO THE AREA. HEAT AND HUMIDITY WILL RETURN BY FRIDAY AS THIS FRONT MOVES NORTH. HIGHS TODAY WILL BE IN THE LOWER TO MID 80S. LOWS THE NEXT SEVERAL NIGHTS WILL BE AROUND 70. HIGHS THIS WEEKEND WILL BE AROUND 90 DEGREES. && .UPDATE... ISSUED AT 1128 AM EDT THU AUG 21 2014 BROAD ISENTROPIC LIFT/LOW LEVEL MOISTURE TRANSPORT WILL CONTINUE THROUGH THIS AFTERNOON FROM THE MID MS RIVER VALLEY EXTENDING EASTWARD TO THE OHIO RIVER VALLEY. RUC INITIALIZATION SUPPORT CONVECTIVE ENHANCEMENT TO SMALL SCALE VORT MAX TRACKING ACROSS SOUTH/SOUTHEAST PORTIONS OF THE AREA THIS MORNING...WITH SOME INDICATIONS OF MCV HAVING ALSO FORMED ACROSS FAR NORTH CENTRAL INDIANA. A BRIEF LULL IN PRECIP IS POSSIBLE IN WAKE OF THIS FEATURE OVER NEXT FEW HOURS...BUT A STEADY STREAM OF SMALLER SCALE WAVES EMBEDDED IN NORTHWEST UPPER FLOW AND POOLED LOW LEVEL MOISTURE AXIS ACROSS MUCH OF LOCAL AREA WILL SUPPORT AT LEAST CHANCE TSRA MENTION THROUGH THE REMAINDER OF THE AFTERNOON. SLIGHTLY MORE STABLE CONDITIONS ASSOCIATED WITH MORNING CLOUDS/PRECIP MAY TEMPER SEVERE THREAT AT LEAST THROUGH MUCH OF THE AFTERNOON HOURS. POCKET OF STRONGER MID/UPPER FLOW IS EXPECTED TO OVERSPREAD THE AREA THIS EVENING AND THIS MAY SUPPORT SOUTHEAST PROPAGATION OF POTENTIAL CONVECTIVE SYSTEM FORMING UPSTREAM OF LOCAL AREA TONIGHT. RADAR ESTIMATES THAT MANY LOCATIONS FROM WESTERN STARKE COUNTY INTO GRANT COUNTY HAVE EXPERIENCED 1 TO 2 INCHES OF RAINFALL WITH MORNING STORMS...AND SOME HYDRO CONCERNS MAY EVOLVE TONIGHT DEPENDING ON UPSTREAM LATE AFTERNOON/EVENING CONVECTIVE EVOLUTION...BUT WILL HOLD OFF ON ANY HYDRO HEADLINES AT THIS TIME. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 449 AM EDT THU AUG 21 2014 UPPER LEVEL JET DYNAMICS COMBINED WITH THE LEADING EDGE OF THETA E CONVERGENCE WAS HELPING TO TRIGGER ISOLATED STORMS AND AN AREA OF SHOWERS NORTH OF THE FRONT. THE STORMS WERE HIGH BASED EARLY THIS MORNING...BUT SHOULD BECOME MORE SURFACE BASED AS THE FRONT MOVES NORTH AND AS THE ATMOSPHERE DESTABILIZES WITH DAYTIME HEATING LATER TODAY. THETA E FLUX WILL INCREASE TONIGHT...WITH A BETTER CHANCE FOR SHOWERS AND STORMS AS AN UPPER LEVEL DISTURBANCE TOPS THE UPSTREAM RIDGE AND MOVES INTO THE WESTERN GREAT LAKES REGION. THE 12KM NAM APPEARED TO HAVE A REASONABLE HANDLE ON THE TIMING OF THIS UPSTREAM SYSTEM AND THE TRACK OVER THE UPPER LEVEL RIDGE...SO HAVE LIKELY THUNDERSTORM CHANCES LATER TONIGHT. SEVERE STORMS ARE POSSIBLE GIVEN DEEP LAYER SHEAR TOPPING OUT AT 30 TO 40 KNOTS. HAVE RAISED HIGHS TODAY. THE NAM/MET HAS RAISED HIGHS TODAY 5 DEGREES AT SBN AND APPEARS ON TRACK...COMING MORE IN LINE WITH THE GFS/MAV. 850 MB TEMPS WILL BE BETWEEN 18C AND 19C TODAY...AND SOME SUN TODAY SHOULD ALLOW HIGHS TO RISE TO BETWEEN 82F AND 86F. && .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 449 AM EDT THU AUG 21 2014 MAIN CONCERN THIS PERIOD IS POTENTIAL FOR EXCESSIVE HEAT AS STRONG UPR LEVEL RIDGE BUILDS INTO THE AREA RESULTING IN HEAT INDEX READINGS IN THE 90S EACH AFTN. ALTHOUGH THESE READINGS ARE A BIT BLO OUR ADVISORY CRITERIA... IMPACTS MAY BE GREATER THAN USUAL DUE TO EXPECTED RATHER LONG DURATION OF THE HEAT WAVE... AND DIFFICULTY FOR PEOPLE TO BECOME ACCLIMATED TO THE HEAT GIVEN ABNORMALLY COOL TEMPS THUS FAR THIS SUMMER. CONVECTION AT NOSE OF A WK WLY LLJ MAY BE ONGOING IN OUR AREA AT THE START OF THE PERIOD FRIDAY MORNING. WK LOW LEVEL WAA PATTERN AND STNRY SFC BOUNDARY DRAPED ACROSS NERN PORTION OF THE CWA EXPECTED FRI WHICH MAY PROVIDE FOCUS FOR REDEVELOPMENT IN THE AFTN AS AIRMASS DESTABILIZES. THIS BOUNDARY EXPECTED TO REMAIN OVER THE AREA FRI NGT WITH NOSE OF WSWLY LLJ OVER THE MID MS VALLEY PROVIDING FORCING FOR CONVECTION UPSTREAM OVERNIGHT WHICH COULD BE SUSTAINED INTO OUR AREA GIVEN LINGERING WK/MODERATE ELEVATED INSTABILITY. RATHER STRONG NWLY UPR LEVEL FLOW ON EAST SIDE OF MS VALLEY RIDGE WILL PROVIDE DECENT DEEP LAYER SHEAR FRI/FRI NGT...ESPECIALLY OVER ERN PORTIONS OF THE CWA WHICH ALSO COULD AID IN CONVECTIVE PERSISTENCE AS WELL AS SUPPORT A FEW STRONG/SVR STORMS AROUND PEAK HEATING FRI AFTN/EVE. DOUBT CONVECTION WILL BE SUFFICIENTLY WIDESPREAD OR LAST LONG ENOUGH TO HOLD TEMPS DOWN SIGNIFICANTLY FRIDAY. GIVEN H85 TEMPS PROGGED IN THE 19-20C RANGE STAYED CLOSE TO PREVIOUS FCST WITH HIGHS RANGING FROM THE M80S NE TO AROUND 90 SW. DWPTS SHOULD ALSO BE RISING TO THE L-M70S WHICH WILL RESULT IN AFTN HEAT INDICES ABOUT 5-10F HIGHER THAN TEMPS. LIGHT WINDS FRI NGT SHOULD ALLOW FOR SOME RADIATIONAL COOLING SO EXPECT MINS TO BE IN THE U60S NE AND L70S SW. SIMILAR CONDITIONS EXPECTED SATURDAY. UPR RIDGE AXIS SHOULD MOVE SLIGHTLY EAST INTO OUR AREA AS STRONG TROF MOVES ACROSS THE NRN ROCKIES. E-W ORIENTED SURFACE BOUNDARY WILL LIKELY REMAIN OVER THE AREA PROVIDING SOME FOCUS FOR CONVECTION AS AIRMASS DESTABILIZES DURING THE DAY. WK LOW LEVEL GRADIENT WINDS AND VERY MOIST AIRMASS OVER THE AREA SHOULD AGAIN LIMIT HEATING BUT EXPECT SUFFICIENT MIXING TO ALLOW FOR HIGHS CLOSE TO FRIDAYS READINGS AS SUGGESTED BY MAV MOS TEMPS. STNRY SFC BOUNDARY SHOULD LIFT NORTH OF OUR CWA SAT NGT-SUNDAY AS SFC LOW DEEPENS OVER THE NRN PLAINS. THIS SHOULD RESULT IN MAINLY DRY CONDITIONS BY SUNDAY WITH TEMPS CONTG TO SLOWLY WARM. NRN PLAINS LOW EXPECTED TO LIFT NE-E INTO ONTARIO MONDAY AND TO QUEBEC TUE WITH TRAILING WK CDFNT DROPPING SOUTH INTO OUR AREA BY THAT TIME. SOME SUPPRESSION OF UPR RIDGE PER ECMWF SOLUTION SEEMS APPROPRIATE AS SHRTWV BREAKS OVER THE TOP ACROSS THE UPR GRTLKS... SO WKNG CAPPING INVERSION/CHC TSTMS... AND SLIGHTLY LOWER TEMPS FCST BY TUE. MEDIUM RANGE MODELS DIFFERING SOLUTIONS WRT PERSISTENCE OF UPR RIDGE TUE LEADING TO EVEN GREATER DIFFERENCES BY WED WITH ECMWF SUGGESTING RIDGING BUILDING BACK INTO OUR REGION AS CLOSED LOW DEVELOPS IN THE WRN U.S., WHILE GFS FCSTG MORE PROGRESSIVE WRN TROF WITH A STRONG SHRTWV APPROACHING THE MIDWEST BY WED EVE. GIVEN LARGE DIFFERENCES STAYED CLOSE TO PREVIOUS FCST WHICH WAS FOR CONTD SLOW COOLING TREND AND A LOW CHC OF TSTMS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 553 AM EDT THU AUG 21 2014 UPPER LEVEL JET DYNAMICS WERE HELPING TO TRIGGER STORMS IN AN AREA FROM SOUTHERN WI INTO NW INDIANA. HAVE KEPT THE BULK OF THE TIMING OF THE STORMS IN THE ONGOING TAFS...AND HAVE KEPT THUNDER TONIGHT. THETA E FLUX WILL INCREASE TONIGHT...WITH MORE WIDESPREAD ACTIVITY EXPECTED AS AN UPPER LEVEL SYSTEM DROPS SOUTHEAST INTO THE AREA. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...MARSILI SYNOPSIS...SKIPPER SHORT TERM...SKIPPER LONG TERM...JT AVIATION...SKIPPER VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1154 PM CDT WED AUG 20 2014 .SHORT TERM /TONIGHT/... ISSUED AT 340 PM CDT WED AUG 20 2014 TONIGHTS FORECAST IS QUITE DIFFICULT AND THE MODELS ARE NOT MUCH HELP. A WARM FRONT ACROSS IOWA STRETCHES FROM A LOW OVER WEST CENTRAL SOUTH DAKOTA. THETA-E ADVECTION AND SOME MODEST INSTABILITY KEPT THUNDERSTORMS FESTERING AHEAD OF THE FRONTAL BOUNDARY ALL DAY LONG AND SHEAR ACTUALLY INCREASED THROUGH THE AFTERNOON HOURS. THE MODELS CONTINUE THE SHOWERS/STORMS ALONG AND AHEAD OF THE FRONTAL BOUNDARY IN A ZONE OF WARM ADVECTION THROUGH THE AFTERNOON HOURS INTO EARLY EVENING. THE HRRR AND HOPWRF THEN SQUELCH THE PRECIP IN IOWA OVERNIGHT WHILE THE NAM CONTINUES TO DEVELOP STORMS ACROSS NORTH CENTRAL/NORTHEAST IOWA...ESPECIALLY WITH A LOW LEVEL JET THAT INTENSIFIES LATER THIS EVENING. IT IS VERY HARD TO SAY WHERE THAT BOUNDARY WILL LIFT TO THIS EVENING...OR WILL IT REMAIN FAIRLY STATIONARY. I AM REASONABLY CERTAIN THAT WE WILL NOT BE DRY ACROSS THE NORTH BUT I AM SKEPTICAL ABOUT KEEPING 60-70 POPS IN THAT AREA GIVEN THE TRENDS FOR THE PRECIP TO SLOWLY LIFT NORTH. THE MAIN ADJUSTMENTS TO THE GOING FORECAST WERE TO LOWER POPS SOME ACROSS THE NORTH AND MENTION HEAVY RAIN ACROSS A PART OF THE NORTH CENTRAL AND NORTHEAST. HOWEVER...IF THE NAM12 IS CORRECT MY FORECAST WILL NEED TO BE ADJUSTED ONCE THE LLJ COMES INTO PLAY AFTER 03Z OR SO AS HIGHER POPS WILL BE NEEDED FURTHER SOUTH. HEAVY RAINFALL WILL ALSO BE MORE OF A CONCERN ACROSS AREAS NORTH OF HIGHWAY 20. .LONG TERM /THURSDAY THROUGH WEDNESDAY/... ISSUED AT 340 PM CDT WED AUG 20 2014 RELATIVELY ACTIVE CONDITIONS TO PERSIST FOR MUCH OF THE LONG TERM WITH BROAD WSW FLOW ALOFT AND SURFACE BOUNDARY NEARBY. ANY ONGOING CONVECTION ON THURSDAY MORNING SHOULD DISSIPATE WITH FORCING WEAKENING. WARM SECTOR WILL BE IN PLACE WITH TEMPERATURES CLIMBING NICELY THROUGH THE DAY. STILL MAY SEE SOME MID TO HIGH CLOUDS OVERHEAD AND THIS MAY LIMIT DAYTIME HIGHS...HOWEVER STILL A VERY WARM AND HUMID DAY EXPECTED FOR MOST LOCATIONS. SURFACE BOUNDARY WILL EASE INTO NORTHERN IOWA ON THURSDAY NIGHT WITH SOME SCATTERED CONVECTION EXPECTED ALONG THE FRONT OVERNIGHT. THESE STORMS ARE EXPECTED TO WEAKEN OVERNIGHT TOWARD DAYBREAK AS INFLOW WEAKENS AND COL REGION PUSHES INTO THE STATE. FRIDAY WILL SEE THE COL PASS THROUGH IOWA WITH LIMITED CONVECTION CHANCES FOR MUCH OF THE DAY. HOWEVER...A MORE VIGOROUS SHORTWAVE WILL EJECT INTO THE PLAINS LATER FRIDAY WITH INCREASING FLOW INTO THE FRONT LATE FRIDAY INTO FRIDAY NIGHT. MODELS HAVE ALL BEEN INDICATING RATHER ROBUST CONVECTION BY LATE FRIDAY ACROSS THE PLAINS PUSHING INTO IOWA OVERNIGHT. HAVE CONTINUED THE HIGHER POPS ON FRIDAY NIGHT...ESPECIALLY ACROSS THE NORTHWEST WHERE THE BEST FORCING AND INFLOW INTO SYSTEM IS ANTICIPATED. THE THREAT FOR CONVECTION WILL PERSIST INTO THE WEEKEND AND EARLY NEXT WEEK AS THE FRONTAL BOUNDARY REMAINS NEAR THE STATE. AT THIS POINT...IT APPEARS MUCH OF THE CONVECTION THIS WEEKEND WILL BE NEAR NORTHERN IOWA WITH HOT AND HUMID CONDITIONS IN THE SOUTH. THE BULK OF THE SYSTEM IS NOT EXPECTED TO PASS THROUGH THE REGION UNTIL THE MIDDLE OF NEXT WEEK WHEN GOOD COVERAGE OF STORMS IS ANTICIPATED TUESDAY NIGHT INTO WEDNESDAY. TEMPERATURES WILL REMAIN VERY WARM TO HOT SOUTH OF THE BOUNDARY DURING THIS TIME. THE THREAT FOR HEAVY RAINFALL WILL BE EVER PRESENT WITH THIS CONVECTION FOR MUCH OF THE FORECAST. PWAT VALUES WILL IN GENERAL BE AT OR ABOVE 1.50" WITH CONVECTION EAST OR SOUTHEAST AND TRAINING A POSSIBILITY FROM TIME TO TIME. WHILE WIDESPREAD FLOODING IS NOT EXPECTED GIVEN MATURE VEGETATIVE GROWTH...LOCALIZED FLOODING MAY OCCUR. THE PRIMARY FLASH FLOOD THREAT WILL REMAIN IN URBAN AREAS. HOWEVER...IF SEVERAL NIGHTS OF RAIN DO OCCUR IN THE SAME AREA...A MORE GENERALIZED FLASH FLOOD THREAT MAY MATERIALIZE. THE OTHER CONCERN WILL BE WITH HOT AND HUMID CONDITIONS SOUTH OF THE BOUNDARY. HEAT INDEX VALUES ARE EXPECTED TO CLIMB ABOVE 100 DEGREES FROM TIME TO TIME AND MAY BECOME PROBLEMATIC...ESPECIALLY IN SOUTHERN IOWA SHOULD SEVERAL DAY STRING TOGETHER OF HOT AND STICKY CONDITIONS. MUCH WILL DEPEND ON THE EXTEND OF CONVECTION AND WHERE OUTFLOW BOUNDARYS AND SUBSEQUENT CONVECTION END UP. AT THIS POINT...GIVEN THE UNCERTAINTY...NO HEADLINES FOR HEAT WILL BE ISSUED. && .AVIATION...21/06Z ISSUED AT 1150 PM CDT WED AUG 20 2014 BOUNDARY NEAR NORTHERN IOWA WILL ALLOW FOR TSRA CHANCES AT SITES. HAVE INCLUDED MENTION AT NORTHERN SITES KMCW/KALO...WITH CONDITIONS DROPPING TO MVFR OR IFR...POSSIBLY LOWER IF HEAVY RAIN REDUCES VISIBILITIES NEAR 12Z. SYSTEM WILL PUSH EAST...WITH A RETURN TO VFR CONDITIONS AT SITES. WINDS WILL BE FROM THE SOUTH AND MAY BE GUSTY IN THE AFTERNOON. ADDITIONAL CHANCES FOR SHRA/TSRA WILL BE POSSIBLE AT SITES LATE IN THE PERIOD...THOUGH HAVE LEFT OUT MENTION ATTM DUE TO UNCERTAINTIES IN TIMING AND PLACEMENT. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...FAB LONG TERM...COGIL AVIATION...AWB
AREA FORECAST DISCUSSION
NWS WICHITA KS
305 PM CDT THU AUG 21 2014 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 252 PM CDT THU AUG 21 2014 TNGT-SAT: ANOTHER HOT AFTERNOON UNDER WAY ACROSS THE FORECAST AREA TODAY...AS BREEZY SOUTHWEST WINDS ARE LEADING TO TEMPS SLIGHTLY WARMER THAN THE PREVIOUS FEW DAYS. SURFACE DEWPOINTS MIXING OUT A LITTLE BETTER OVER SOUTH CENTRAL KS...BUT NOT AS FAST OVER SE KS...SO COULD SEE HEAT INDEX VALUES HOVER NEAR 105 FOR AN HOUR OR TWO LATE THIS AFTERNOON...ESPECIALLY OVER SE KS. MID/UPPER LEVEL FLOW IS MORE OUT OF THE SW THIS AFTERNOON...WITH LATEST WATER VAPOR IMAGERY SHOWING A NICE MOISTURE PLUME OUT OF THE SW US FROM THE MONSOONAL FLOW INTO SW KS. LATEST SURFACE ANALYSIS SHOWS SURFACE TROUGH LOCATED GENERALLY JUST EAST OF KGLD TO NEAR KGCK. INSTABILITY AXIS CONTINUES ALONG THIS BOUNDARY WITH SBCAPES VALUES OF 2500-2800 J/KG. THE COMBINATION OF THE HEAT AND UNSTABLE AIRMASS...IS EXPECTED TO ERODE THE CAP AND DEVELOP STORMS ALONG THIS INSTABILITY AXIS LATE THIS AFTERNOON INTO THIS EVENING. ANY CONVECTION OVER WRN KS WILL SLOWLY MOVE TO THE NORTHEAST AS THE LATE EVENING PROGRESSES...AS LOW LEVEL MOISTURE TRANSPORT FROM THE OK PANHANDLE INCREASES ALONG THE WRN EDGE OF THE FORECAST AREA. SO EXPECT STORMS TO MOVE INTO CENTRAL KS LATE THIS EVENING...WITH SOME BACKBUILDING POSSIBLE ACROSS PORTIONS OF CENTRAL KS AT LEAST UNTIL MIDNIGHT. EXPECT MOST OF THE CONVECTION TO BE LOCATED ALONG OR NORTH OF HIGHWAY 56 FROM GREAT BEND TO MCPHERSON AS MOISTURE TRANSPORT FOCUSES THE CONVECTION IN THIS AREA AND MORE TO THE NORTHEAST TOWARDS KMHK AFTER MIDNIGHT. SO WILL KEEP CHANCE POPS GOING FOR THIS CHANCE. NOT EXPECTING MUCH OF CHANGE IN HOW THE GOING FORECAST WILL PLAY OUT FRI/SAT...WITH HOT TEMPS DURING THE DAYTIME HOURS...WITH BETTER MIXING IN WRN SECTIONS OF THE FORECAST AREA. SO MAX TEMPS IN THE MID-UPPER 90S WILL BE COMMON...BUT BETTER MIXING OF SURFACE DEWPOINTS WILL KEEP HEAT INDEX VALUES IN THE 100-104 RANGE. WILL ALSO SEE A VIRTUAL REPEAT OF THE CONVECTIVE CHANCES FOR FRI/SAT AS WELL...AS THE SURFACE BOUNDARY REMAINS JUST TO THE WEST OF THE FORECAST AREA...WITH AFTERNOON/EVENING CONVECTION MOVING NORTHEAST OVER PORTIONS OF CENTRAL KS FOR BOTH FRI AND SAT NIGHTS. KETCHAM .LONG TERM...(SUNDAY THROUGH THURSDAY) ISSUED AT 252 PM CDT THU AUG 21 2014 SUN-TUE: SW FLOW CONTINUES ACROSS THE HIGH PLAINS THROUGH THE END OF THE WEEKEND INTO THE BEGINNING OF THE WEEK...WITH EACH SUCCESSIVE SHORTWAVE IN THE FLOW HELPING TO PUSH THE FRONTAL BOUNDARY A LITTLE CLOSER TOWARDS THE FORECAST AREA FOR SUN. BOTH THE GFS AND ECMWF SHOW THIS BOUNDARY DRIFTING INTO THE FORECAST AREA FOR SUN-SUN NIGHT. THIS TIME FRAME LOOKS LIKE THE BEST CHANCE FOR WIDELY SCATTERED SHOWERS/STORMS...ESPECIALLY FOR AREAS WEST OF THE KS TURNPIKE. CHANCE FOR STORMS LOOKS A LITTLE MORE UNCERTAIN FOR MON/TUE...AS POSITION OF THE BOUNDARY OVER THE FORECAST AREA WILL BE IN QUESTION. BOTH THE GFS AND ECMWF BOTH SUGGEST THAT THE BOUNDARY WILL BE LOCATED SOMEWHERE OVER SRN KS...AND POSSIBLY WASH OUT OVER THE AREA BY TUE. THINK STORM CHANCES WILL HAVE ALOT OF MESOSCALE EFFECTS...SO HARD TO PIN DOWN WHERE THE BEST CHANCE OF STORMS WILL BE LOCATED IN THE WEAKLY CAPPED ENVIRONMENT THAT WILL BE OVER THE AREA. REST OF THE EXTENDED: LOTS OF UNCERTAINTY ON HOW THE MIDDLE OF THE WEEK WILL EVOLVE...AS THE MEDIUM RANGE MODELS CANT DECIDE ON WHAT TO DO WITH TEMPS/PRECIP AS A MORE POTENT SHORTWAVE MOVES OUT OF THE SW FLOW AND ACROSS THE NRN PLAINS. GFS IS A LOT MORE PROGRESSIVE WITH THE TIMING OF THIS SHORTWAVE...BRINGING IT ACROSS THE PLAINS ON WED...WITH A COLD FRONT PUSHING SOME COOLER AIR INTO THE PLAINS FOR WED THRU THE END OF THE WEEK. THE ECMWF ON THE OTHER HAND IS A LOT SLOWER WITH THIS IMPULSE...HOLDING IT BACK UNTIL LATER IN THE WEEK...WHICH WOULD SUGGEST THAT THE HOT TEMPS WILL STAY AROUND POSSIBLY THROUGH THU OR FRI. SO POPS FOR THIS TIME FRAME WILL ALSO BE HIGHLY CONTINGENT ON WHEN THE BOUNDARY MAKES ITS WAY ACROSS. KETCHAM && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1256 PM CDT THU AUG 21 2014 THE MAIN FORECAST PROBLEM FOR THE NEXT 24 HOURS REMAINS CONVECTION. THE HRRR MODEL RUNS THIS MORNING HAVE ALL CONTINUED TO SHOW CONVECTIVE INITIATION IN AN AREA ROUGHLY FROM HUTCHINSON TO DODGE CITY. THIS IS JUST AHEAD OF A STALLED FRONT. CONVERGENCE ALONG THIS BOUNDARY IS FAVORABLE AND THE STRUCTURE OF THE ATMOSPHERE HAS NOT SIGNIFICANTLY CHANGED MUCH. THE HRRR FORECASTS FOR THE LAST SEVERAL DAYS HAVE BEEN PRETTY ACCURATE AND THERE IS NO REASON TO THINK TODAYS WILL NOT BE. THAT SAID...THE MODEL IS TRENDING TOWARD LESS PRECIPITATION MOVING INTO NORTH-CENTRAL KANSAS...WHILE TRENDING MORE TOWARD STORMS REMAINING SOUTH AND BUILDING SOUTH INTO THE TEXAS PAN HANDLE. KEPT CONTINUITY IN THE TAFS FOR NOW. BEST TIME FOR CONVECTION TO AFFECT THE TAFS IS FROM 00Z-05Z. THIS TIMING IS MUCH EARLIER THAN THE LAMP OUTPUT...BUT MORE IN LINE WITH THE HRRR. THE LAMP OUTPUT HAS BEEN TRENDING TOWARD THE HRRR. COOK && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 77 98 75 97 / 10 10 10 0 HUTCHINSON 76 99 74 97 / 20 10 20 0 NEWTON 76 98 74 96 / 20 10 10 0 ELDORADO 77 98 74 97 / 10 10 10 0 WINFIELD-KWLD 77 98 75 98 / 0 10 10 0 RUSSELL 74 98 73 95 / 20 10 30 0 GREAT BEND 74 97 73 96 / 20 10 20 0 SALINA 77 100 74 97 / 20 10 20 0 MCPHERSON 76 98 74 96 / 20 10 20 0 COFFEYVILLE 76 98 74 98 / 0 10 0 0 CHANUTE 76 97 73 97 / 0 10 0 0 IOLA 76 97 73 97 / 0 10 0 0 PARSONS-KPPF 76 98 73 98 / 0 10 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS WICHITA KS
110 PM CDT THU AUG 21 2014 ...UPDATED FOR 18Z AVIATION DISCUSSION... .SYNOPSIS... ISSUED AT 355 AM CDT THU AUG 21 2014 SCATTERED THUNDERSTORMS THAT HAVE BEEN OCCURRING FROM NORTHEAST CO TO CENTRAL & EASTERN NEBRASKA HAVE BEEN OCCURRING ALONG A SLOW SE-MOVING COLD FRONT CURVING FROM THE EASTERN DAKOTAS TO THE CO/NM BORDER. THE DRIVING MECHANISM HAS BEEN A BROAD MID-LEVEL TROF EXTENDING FROM THE WESTERN DAKOTAS TO EXTREME NORTHEAST NM. THIS PATTERN IS PRODUCING YET ANOTHER VERY WARM NIGHT ACROSS THE WFO WICHITA PREMISES WHERE SOUTH 15 TO 25 MPH WINDS HAVE HELD TEMPERATURES TO THE LOWER 80S IN ALL AREAS. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 355 AM CDT THU AUG 21 2014 TODAY: THE LARGE MID-UPPER HIGH COVERING THE GULF COAST REGION THAT HAS BEEN A TOPIC THE PAST 3 NIGHTS IS BEHAVING AS EXPECTED...SPREADING SLOWLY WEST ACROSS THE LOWER MS VALLEY. THIS WOULD FORCE THE BROAD MID-LEVEL TROUGH SITUATED OVER THE WESTERN PLAINS NE ACROSS NEBRASKA WHERE IT`LL SHEAR QUICKLY TODAY. THE RESULT: MORE DRY WEATHER FOR THE NEIGHBORHOOD TODAY. TONIGHT: THE FOCUS SHIFTS TO THUNDERSTORM POTENTIAL. PERSISTENT SURFACE TROFFING ALONG THE FRONT RANGE WILL CONTINUE INDUCING FAIRLY RICH MOISTURE TO MIGRATE NE ACROSS WESTERN & CENTRAL KS BUT MID-LEVEL DYNAMICS ARE A BIT FEEBLE & WITH WARM MID LEVELS...THUNDERSTORM POTENTIAL WOULD BE LIMITED WITH ANY CHANCES CONFINED TO CENTRAL KS. FRI & FRI NIGHT: AFTER ANOTHER HOT & BREEZY DAY A FEW THUNDERSTORMS MAY VENTURE INTO THE NEIGHBORHOOD FROM WESTERN KS LATE TONIGHT AS A MORE ROBUST MID-LEVEL SHORTWAVE QUICKLY STRENGTHENS OVER THE NEBRASKA PANHANDLE & NORTHEAST CO BUT WITH THE MASSIVE MID-UPPER HIGH CONTINUING TO SPREAD/RETROGRADE TOWARD THE SOUTHERN PLAINS THE SHORTWAVE WOULD BE FORCED NE TOWARD THE NEBRASKA/SD BORDER. AS SUCH THE BETTER CHANCES OF THUNDERSTORMS WOULD OCCUR ACROSS THE WESTERN HALF OF KS. HAVE ASSIGNED 20-30% POPS TO AREAS PRIMARILY ALONG & W OF I-135. SAT & SAT NIGHT: WITH THE AFORE-MENTIONED INTENSE MID-LEVEL SHORTWAVE BEING "FORCED" TO MOVE DUE N OVER THE DAKOTAS ON SAT HOT & DRY WEATHER WILL AGAIN GRIP ALL AREAS ON SAT. THUNDERSTORM POTENTIAL SHOULD BEGIN TO INCREASE SAT NIGHT AS INTENSE CYCLOGENESIS ENSUES OVER THE MT/ND BORDER. A MID-LEVEL SHORTWAVE WILL SCOOT DUE EAST AROUND THE BASE OF CYCLONE TOWARD...THEN ACROSS...THE CO/KS BORDER. THIS WOULD FORCE A COLD FRONT ESE ACROSS THE CO/KS BORDER LATE SAT NIGHT. THUNDERSTORMS DEVELOPING OVER THE WESTERN PLAINS WOULD SURGE E/NE TOWARD...THEN ACROSS...CENTRAL & SOUTH-CENTRAL KS LATE SAT NIGHT & EARLY SUN MORNING. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 355 AM CDT THU AUG 21 2014 WHILE THUNDERSTORMS ARE CERTAINLY ANTICIPATED FOR SUN & SUN NIGHT THE BETTER CHANCES ARE STILL EXPECTED TO OCCUR FROM MON NIGHT THRU TUE NIGHT WHEN THE STRONGEST/MOST INTENSE MID-UPPER WAVE SURGES E ACROSS KS & NEBRASKA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1256 PM CDT THU AUG 21 2014 THE MAIN FORECAST PROBLEM FOR THE NEXT 24 HOURS REMAINS CONVECTION. THE HRRR MODEL RUNS THIS MORNING HAVE ALL CONTINUED TO SHOW CONVECTIVE INITIATION IN AN AREA ROUGHLY FROM HUTCHINSON TO DODGE CITY. THIS IS JUST AHEAD OF A STALLED FRONT. CONVERGENCE ALONG THIS BOUNDARY IS FAVORABLE AND THE STRUCTURE OF THE ATMOSPHERE HAS NOT SIGNIFICANTLY CHANGED MUCH. THE HRRR FORECASTS FOR THE LAST SEVERAL DAYS HAVE BEEN PRETTY ACCURATE AND THERE IS NO REASON TO THINK TODAYS WILL NOT BE. THAT SAID...THE MODEL IS TRENDING TOWARD LESS PRECIPITATION MOVING INTO NORTH-CENTRAL KANSAS...WHILE TRENDING MORE TOWARD STORMS REMAINING SOUTH AND BUILDING SOUTH INTO THE TEXAS PAN HANDLE. KEPT CONTINUITY IN THE TAFS FOR NOW. BEST TIME FOR CONVECTION TO AFFECT THE TAFS IS FROM 00Z-05Z. THIS TIMING IS MUCH EARLIER THAN THE LAMP OUTPUT...BUT MORE IN LINE WITH THE HRRR. THE LAMP OUTPUT HAS BEEN TRENDING TOWARD THE HRRR. COOK && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 99 77 97 75 / 10 10 10 10 HUTCHINSON 99 76 99 75 / 10 20 10 20 NEWTON 98 76 97 75 / 10 10 10 10 ELDORADO 98 77 98 75 / 10 10 10 10 WINFIELD-KWLD 99 77 97 76 / 0 0 10 10 RUSSELL 100 74 97 74 / 20 20 10 30 GREAT BEND 100 74 97 74 / 20 20 10 20 SALINA 101 77 99 75 / 10 20 10 20 MCPHERSON 100 76 98 75 / 10 20 10 20 COFFEYVILLE 98 76 97 74 / 10 0 0 0 CHANUTE 98 76 97 74 / 10 0 0 0 IOLA 97 76 97 74 / 10 0 0 0 PARSONS-KPPF 97 76 97 74 / 10 0 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
606 AM CDT Thu Aug 21 2014 ...Updated aviation discussion... .SHORT TERM...(Today and tonight) ISSUED AT 219 AM CDT THU AUG 21 2014 An upper level low will continue to slowly move eastward today through tonight with a large upper level high centered over the southeast United States. Mid levels of the atmosphere become more saturated as today progresses with increased cloudiness expected this evening into the overnight period. A trough of low pressure will be observed at the surface, extending from northwest Kansas back into southeast Colorado. Meanwhile, a dome of high pressure will be located across the southeast United States. These features will allow south to southwest winds to be felt today through tonight with breezy conditions likely this afternoon as the atmosphere mixes. During peak heating, a few thunderstorms may form ahead of the aforementioned trough. Severe storms are not expected, but with such a wide T/Td separation, a few storms may be capable of producing strong winds up to 55 mph. Any storms that do form should move eastward this evening then move out of or dissipate by or around midnight. Highs today are forecasted to reach into the mid to upper 90s with around 100 degrees across the KS/OK border. Lows tonight are expected to range from the upper 60s across the KS/CO border to the mid 70s across south central Kansas. .LONG TERM...(Friday through Wednesday) ISSUED AT 315 AM CDT THU AUG 21 2014 A southwesterly flow will persist across the Central Plains through the weekend period into early next week as an upper ridge axis remains nearly stationary from the lower Mississippi Valley to the Western Great Lakes Region. All the models are in decent agreement with an upper low, located just off the coast of southern California at 00z Thursday, weakening as it approaches the central Rockies late week and early this weekend. Cloud cover and precipitation chances will improve as tropical moisture increases ahead of this approaching upper level system so will retain higher chances across west central and north central Kansas Friday night given the timing of this weakening upper system and location of a surface boundary. Precipitation chances will then continue from late this weekend through early next week as another upper level trough approaches the area from the west and a cold front drops south into western Kansas. Temperatures around 100 degree on Friday still looks on track based on the 850mb to 700mb temperature trends from the ECMWF, NAM, and GFS. Temperatures will be slightly cooler over the weekend period given the increase in tropical moisture and slightly cooler temperatures in the 850mb to 700mb level at 00z Sunday and 00z Monday. Temperatures will fall back to more seasonal levels early next week as the cold front moves south into portions of western Kansas. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) ISSUED AT 604 AM CDT THU AUG 21 2014 06z NAM BUFR soundings along with 10z surface observations and the latest HRRR indicating cloud bases early this morning and late this afternoon will be at or above 5000ft AGL. A few widely scattered showers across north central Kansas will taper off by 15z. Late day instability will result in another slight chance for showers and thunderstorms along a surface boundary which will extend across western Kansas, however at this time given how widely scattered these storms will be late today have decided not to include them in the 12z tafs. Gusty southwest winds at 15 to near 20 knots today will subside back into the 10 to 15 knot range by sunset. && .PRELIMINARY POINT TEMPS/POPS... DDC 98 73 99 73 / 20 20 20 20 GCK 97 71 98 70 / 20 20 20 30 EHA 96 70 97 70 / 20 20 20 30 LBL 99 72 99 73 / 20 20 20 20 HYS 99 73 99 73 / 20 20 20 30 P28 99 76 100 77 / 10 10 10 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Hovorka_42 LONG TERM...Burgert AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS TOPEKA KS
319 AM CDT Thu Aug 21 2014 .SHORT TERM...(Today and Tonight) Issued at 245 AM CDT THU AUG 21 2014 Thunderstorms again not far from the local area and could skirt the northwestern counties over the next few hours. This appears the result of better moisture and moisture convergence via the low level jet, with with southwest low-mid level flow likely keeping this focused to the north. Some gustiness in surface winds has been common overnight due to the stronger jet, helping keep temps in the upper 70s to lower 80s. Will keep small mention of precipitation very early in the far north as decreasing mass flow occurs from the nocturnal jet mixing out through the mid morning. Models are very similar with 850mb temps rising another 1-2C with mixing well through this layer bringing highs up in kind. Dewpoints should remain in the mid 60s to around 70 and bring apparent temps into the 101 to 105 range, but confidence in the higher levels being widespread or more than brief is too low for a Heat Advisory. For tonight, the low level jet, though weaker, looks to be displaced a bit farther southeast, with deep layer moisture increasing from the southwest. Setup doesn`t appear as strong as that seen to the northwest this morning, but small thunder chances seem in order for mainly northern and central areas. .LONG TERM...(Friday through Wednesday) Issued at 245 AM CDT THU AUG 21 2014 Friday and through the weekend the heat continues, as upper ridge remains solid to the east of the forecast area and noses northward into the Great Lakes through this period. Shortwave lifts northeast out of the desert southwest through the western periphery of the upper high and into the northern plains by early Sunday, bringing periodic chances for rain along our northern and western borders. Eastern areas remain capped as influence of upper ridge prevails. High temperatures may cool along the north if clouds or rain chances can materialize, but mid to upper 90s continue in the eastern counties. Heat indicies Friday near 100-105 and come down just a few degrees each day over the weekend. GFS and EC both lift leading shortwave trof into the northern plains by late weekend. While both then lift the larger eastern lobe of the upper trof into southern Canada, the EC is then deeper and stronger with the next piece of energy to move into the back side of the longwave trof over the Pacific Northwest. The GFS is weaker and more progressive, and swings the trof across the plains by the end of the forecast period Wednesday. The EC retrogrades the energy, which boosts the upper high back northward into the Central Plains. Mondays forecast would be influenced by how far south the surface front can be pushed before southwesterly flow aloft aids in pushing the front back northward. Unfortunately both solutions would suggest even if Monday brings a cooler shot and a chance for precipitation, that this push on Tuesday would make short work of bringing the warm temperatures back north for Tuesday. Progressive GFS would bring front through on Wednesday while the EC holds in the heat another day. Later periods in the forecast certainly reflect probabilistic chances for precipitation and generally focus chances on the west and north where perturbations in the flow have greater chances for influence. && .AVIATION...(For the 06Z TAFs through 06Z Thursday Night) Issued at 1120 PM CDT WED AUG 20 2014 Organized convection appears to be a pretty low probability overnight with models showing the nose of the low level jet mainly north and east of the terminals. Convection has persisted across southern NEB on the nose of the low level jet while additional activity to the south appears to be falling apart. Therefore will continue with a dry forecast. Chances for wind shear continue to be small as sfc winds have remained up this evening indicative of continued mixing. RAP and NAM soundings show only a modest nocturnal inversion that is not very steep and models prog a decent pressure gradient persisting through the night. Because of this I do not expect the boundary layer to become completely decoupled. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...65 LONG TERM...67 AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1120 PM CDT Wed Aug 20 2014 ...AVIATION UPDATE... .SHORT TERM...(This Evening through Thursday) Issued at 333 PM CDT WED AUG 20 2014 A broad upper level ridge axis will continue to amplify across the lower and mid MS river valley over the next 24 hours. A minor upper level trough was located across northeast OK and southeast KS this afternoon, on the western edge of the H5 ridge axis, and will move northeast across southeast KS into western MO this afternoon through early this evening. A shower did pop up across southern Coffey county but did dissipate. This minor H5 trough may provide just enough lift for an isolated shower or thunderstorms along and southeast of I-35 through the late afternoon and early evening hours. I will keep POPS at 14 percent due to the very isolated coverage. During the evening hours scattered thunderstorms will develop across western KS and eastern CO. Most of the thunderstorms will lift northeast into NE but the trailing edge of any thunderstorm complex may move across portions of north central and northeast KS late Tonight and through the mid morning hours of Thursday. At this time any thunderstorm complex that develops across western KS Tonight should be decaying through the early morning hours of Thursday, thus the thunderstorms will not be severe as they move northeast into a less favorable environment across northeast KS. Thursday will be mostly sunny as the H5 ridge axis amplifies across the southern and mid MS river valley. Thunderstorms should remain well west and north of the CWA during the daylight hours. Highs will warm into the mid to upper 90s once again. A few locations across the southwestern counties of the CWA may reach the 100 degree mark. Heat indices will warm into the 100 to 104 degree range during the afternoon hours. Some isolated areas across east central KS may see heat indices reach around 105 degrees. .LONG TERM...(Thursday Night through Wednesday) Issued at 333 PM CDT WED AUG 20 2014 The mid-level flow will remain fairly unchanged through the end of the week into the weekend with a broad ridge remaining in place across much of the central and eastern U.S. and a trough positioned over the western U.S. Thursday night through Saturday the models are in good agreement with the mid-level trough currently over the Pacific Northwest digging southward along the western Rockies with the ridge amplifying further northward toward the Great Lakes region. This pattern will keep southwesterly flow aloft across the region, which will continue to support warm air advection through the end of the week and into the weekend with 850MB temperatures reaching into the 23C-26C degree range. Hot and humid conditions are expected during that period as temperatures become unseasonably warm with highs reaching into the middle to upper 90s Friday and Saturday. These high temperatures combined with dewpoints reaching into the mid 60s to low 70s will result in afternoon heat indices soaring into the 100F to 104F degree range Friday and near 100F degrees on Saturday. We will continue to monitor these conditions closely to see if a heat advisory is needed for Friday. During this period, surface low pressure will become anchored across much of the Northern and Central Plains with a fairly stationary front situated near north central Kansas. There doesn`t appear to be much in the way of forcing along this boundary, however there may be scattered chances for precipitation from late week through the early weekend, especially across north central and northern Kansas. At this time, the better chances for precipitation look to be during the evening and overnight hours as the low-level jet increases over the region. Saturday night and Sunday, models show a strong embedded shortwave trough lifting northeastward across the northern Rockies and into the Northern Plains. This advancing shortwave should be enough to slowly push the stationary front eastward through the region Sunday night and Monday, so have more widespread chance PoPs during that period. This cold front may lift back northward across the area as a warm front, however there is model uncertainty with regards to how far north this warm front will lift, so confidence is low with precipitation chances Monday night through Wednesday. At this time have slight to low-end chance PoPs through that period. The frontal passage Sunday night into Monday will cause winds to shift to the north, providing a bit of relief to the heat with highs dropping into the middle 80s to low 90s Monday. Temperatures are more uncertain for Tuesday and Wednesday depending upon where the warm front is located and whether or not the region is situated within the warm sector, so have highs remaining in the upper 80s to low 90s at this time. && .AVIATION...(For the 06Z TAFs through 06Z Thursday Night) Issued at 1120 PM CDT WED AUG 20 2014 Organized convection appears to be a pretty low probability overnight with models showing the nose of the low level jet mainly north and east of the terminals. Convection has persisted across southern NEB on the nose of the low level jet while additional activity to the south appears to be falling apart. Therefore will continue with a dry forecast. Chances for wind shear continue to be small as sfc winds have remained up this evening indicative of continued mixing. RAP and NAM soundings show only a modest nocturnal inversion that is not very steep and models prog a decent pressure gradient persisting through the night. Because of this I do not expect the boundary layer to become completely decoupled. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...Gargan LONG TERM...Hennecke AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS JACKSON KY
1048 PM EDT FRI AUG 22 2014 .UPDATE... ISSUED AT 1048 PM EDT FRI AUG 22 2014 JUST SENT OUT ANOTHER FORECAST UPDATE. THE FORECAST WERE ADJUSTED SLIGHTLY TO MIRROR CURRENT SENSIBLE WEATHER CONDITIONS ACROSS EASTERN KENTUCKY. SCATTERED SHOWERS AND STORMS WILL BE POSSIBLE THROUGHOUT THE OVERNIGHT PERIOD...AND SHOULD CONTINUE TO TAPER OFF AS THE NIGHT WEARS ON. THERE ARE STILL FLOODING ISSUES ONGOING ACROSS PORTIONS OF THE AREA. AS A RESULT...THERE ARE STILL A NUMBER OF FLOOD WARNINGS AND ADVISORIES IN EFFECT. UPDATE ISSUED AT 934 PM EDT FRI AUG 22 2014 JUST SENT OUT A QUICK UPDATE TO THE ZONE FORECAST. THE FORECAST GRIDS HAVE BEEN MODIFIED EXTENSIVELY OVER THE PAST COUPLE OF HOURS TO ACCOUNT FOR THE WIDESPREAD HEAVY RAINFALL PRODUCING THUNDERSTORMS THAT HAVE BEEN MOVING ACROSS THE AREA. THE PRIMARY AREAS OF CONCERN FOR THE NEXT COUPLE OF HOURS WILL BE PIKE...JOHNSON...AND FLOYD COUNTIES. SHOWERS AND THUNDERSTORMS ARE CONTINUING TO DECREASE IN COVERAGE ALONG THE VIRGINIA BORDER. ADDITIONAL SHOWERS AND STORMS WILL CONTINUE TO MOVE INTO EASTERN KENTUCKY FROM THE NORTHWEST OVERNIGHT. NUMEROUS REPORTS OF FLASH FLOODING HAVE BEEN RECEIVED OUT OF FLOYD...ESTILL...AND PIKE COUNTY SO FAR THIS EVENING. MANY REPORTS WILL LIKELY BE RECEIVED AS OUR 24 HOUR WARNING POINTS ARE ABLE TO RELAY THEM TO US. THE PRECIPITATION PROBABILITIES...SKY COVER...QPF...AND WEATHER TYPE GRIDS HAVE ALL BEEN UPDATED TO BETTER REFLECT REAL TIME WEATHER CONDITIONS ACROSS THE AREA. ANOTHER FORECAST UPDATE WILL BE SENT OUT BEFORE THE END OF THE SHIFT. UPDATE ISSUED AT 735 PM EDT FRI AUG 22 2014 MADE A FEW ADJUSTMENTS TO THE FORECAST GRIDS FOR THE REMAINDER OF THE OVERNIGHT PERIOD TO BETTER REPRESENT CURRENT CONDITIONS AND THE LATEST MODEL DATA. THE CHANGES WERE MADE TO PRECIPITATION PROBABILITIES...PRECIP AMOUNTS...AND WEATHER TYPE GRIDS. THESE CHANGES WERE MOSTLY COSMETIC AND SHOULD NOT CAUSE CHANGES TO THE ZONE FORECAST TEXT PRODUCT THAT WOULD WARRANT ISSUING A NEW FORECAST. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 335 PM EDT FRI AUG 22 2014 18Z SFC ANALYSIS SHOWS A CONVECTIVELY WASHED OUT BOUNDARY JUST NORTH OF THE OHIO RIVER. THIS LEADS BACK WEST TO A DEVELOPING AREA OF LOW PRESSURE OVER THE HIGH PLAINS. MEANWHILE...AN AREA OF HIGH PRESSURE IS FOUND THROUGH THE DEEP SOUTH. ALOFT...A FAIRLY STRONG RIDGE OF HIGH HEIGHTS STRETCHES FROM THE SOUTHERN PLAINS THROUGH THE LOWER MISSISSIPPI RIVER VALLEY AND ACROSS THE DEEP SOUTH WHILE TROUGHING IS FOUND OVER NEW ENGLAND. BETWEEN THESE UPPER LEVEL FEATURES...A COUPLE OF SHORTWAVES ARE PASSING BY TO THE NORTHEAST. THE LEADING ONE OF THESE IS RESPONSIBLE FOR BETTER DEVELOPMENT OF CONVECTION OVER FAR EASTERN KENTUCKY AND WESTERN WEST VIRGINIA. ELSEWHERE...TO THE WEST OF THIS AREA...A FEW SCATTERED SHOWERS AND THUNDERSTORMS ARE TAKING SHAPE ALONG AN OLD OUTFLOW BOUNDARY FROM THE PRE DAWN MCS THAT MOVED THROUGH OHIO EARLY THIS MORNING. WITH THE BULK OF THE ACTIVITY HOLDING OFF UNTIL LATER IN THE AFTERNOON...TEMPERATURES HAVE CLIMBED INTO THE UPPER 80S FOR MOST LOCATIONS WITH A FEW 90 DEGREE READINGS NOTED. DEWPOINTS IN THE LOWER AND MIDDLE 70S ARE MAKING FOR MISERABLE HEAT INDICES THROUGH THE AREA AND WILL BE PROVIDING FUEL FOR STORM DEVELOPMENT. WINDS ARE GENERALLY FROM THE WEST SOUTHWEST AT 5 TO 10 KTS WITH A FEW GUSTS TO 15 KTS. THE MODELS ARE IN GOOD AGREEMENT THROUGH THE SHORT TERM ALOFT AS THEY ALL WOBBLE AND WEAKEN SLIGHTLY THE RIDGE TO OUR WEST IN THE FACE OF THE NEW ENGLAND TROUGH DROPPING NEARLY DUE SOUTH TO THE MID ATLANTIC COAST BY SUNDAY MORNING. DESPITE THE MOVEMENT OF THESE LARGER FEATURES...THE TRACK OF SHORTWAVES WILL CONTINUE TO PASS THROUGH FAR EASTERN KENTUCKY...JUST ORIENTATED MORE NORTH TO SOUTH BY THE END OF THE PERIOD. GIVEN THE MODEL AGREEMENT AND THE SMALLER SCALE NATURE OF THE PERIODIC MCS ACTIVITY HAVE FAVORED THE HIGHER RESOLUTION MODELS LIKE THE HRRR AND NAM12 FOR THIS FORECAST. SENSIBLE WEATHER WILL FEATURE A THREAT OF STORMS INTO THE EVENING... PERHAPS LENGTHENED BY ANY DEVELOPMENT TO THE NORTHWEST THAT COULD MOVE INTO AT LEAST THE NORTHWEST PORTION OF THE JKL CWA AFTER DARK... PER THE LATEST HRRR. SIMILAR TO LAST EVENING...THE MAIN THREATS WITH ANY STORMS WILL BE GUSTY WINDS AND TORRENTIAL DOWNPOURS OF RAIN. AGAIN TONIGHT...WOULD ANTICIPATE PATCHY FOG THROUGH THE AREA AND THE POTENTIAL FOR DENSE SPOTS LOCALLY GIVEN ANY CLEARING. AFTER A MUGGY NIGHT...ANOTHER WARM AND HUMID DAY CAN BE EXPECTED FOR SATURDAY WITH MID LEVEL CHANCES OF SHOWERS AND THUNDERSTORMS THROUGH THE ENTIRETY WITH ONLY A SLIGHT FAVORING OF THE LATE AFTERNOON AND EARLY EVENING HOURS. HIGH PWS AND INSTABILITY DURING THE DAY WILL SET THE TABLE FOR A CONTINUED THREAT OF EXCESSIVE RAINFALL AND STRONG STORMS...THOUGH THE SEVERE RISK WILL BE LIMITED BY A GENERALLY BENIGN NORTHWEST WIND FIELD ALOFT. SIMILARLY...SATURDAY NIGHT WILL BE ANOTHER MUGGY AND WARM ONE WITH PATCHY FOG ANTICIPATED FOR PLACES THAT WOULD HAVE SEEN RAIN DURING THE DAY. CANNOT RULE OUT ADDITIONAL SHOWER AND STORM ACTIVITY INTO EARLY SUNDAY GIVEN THE UPPER LEVEL PATTERN AND NEARBY SFC BOUNDARIES. AGAIN USED THE CONSSHORT AS A STARTING POINT FOR THE T/TD/WINDS THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND SATURDAY NIGHT. AS FOR POPS...ENDED UP IN BETWEEN THE MAV AND THE WETTER MET GUIDANCE FOR MOST OF THE SHORT TERM PORTION OF THE FORECAST. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 255 PM EDT FRI AUG 22 2014 STRONG RIDGING WILL CONTINUE TO DEVELOP OVER THE EASTERN CONUS LATE IN THE WEEKEND THROUGH THE EARLY PART OF NEXT WEEK. AS THE CENTER OF THE HIGH PUSHES OVERHEAD EARLY NEXT WEEK...IT WILL SEND SOME SLIGHTLY DRIER AIR INTO EASTERN KENTUCKY...FINALLY BRINGING A TEMPORARY END TO THE RAIN CHANCES. HAVE BEEN GOING WITH LOW POPS EARLY NEXT WEEK...BUT GIVEN THE NATURE OF THE DRY AIR...HAVE OPTED TO GO WITH DRY WEATHER EARLY TO MIDDLE PART OF NEXT WEEK. IN FACT...DEWPOINTS MAY GET LOW ENOUGH TO WARRANT A FEW TEMPERATURES INTO THE LOWER AND MIDDLE 60S TUESDAY AND WEDNESDAY MORNINGS. CANNOT RULE OUT SOME SHOWERS ON SUNDAY OR SUNDAY EVENING PRIOR TO THE DEPARTURE OF THE BETTER MID LEVEL MOISTURE. HOWEVER...EVEN THIS ACTIVITY WILL LIKELY BE LESS THAN WHAT WE HAVE SEEN RECENTLY. THUS...OVERALL...LOOK FOR A QUIETER STRETCH OF WEATHER INTO THE MIDDLE OF NEXT WEEK. BY LATE IN THE PERIOD. THE RIDGE MAY BEGIN TO BREAK DOWN AS A SHORTWAVE TROUGH MOVING ACROSS THE GREAT LAKES PUSHES A BOUNDARY SOUTHWARD INTO THE OHIO RIVER VALLEY. TOO MUCH UNCERTAINTY WITH THIS BOUNDARY TO GO WITH ANYTHING MORE THAN CHANCE POPS FROM THURSDAY ONWARD. THE 00Z ECMWF HAD PUT THE BOUNDARY OVER EASTERN KENTUCKY...BUT THE 12Z RUN HAS KEPT IT TO THE NORTH THROUGH WEEKS END. IF THE BOUNDARY STAYS NORTH...PROBABLY GOING TO SEE WARMER AND HUMID CONDITIONS PERSISTING THROUGH THE SECOND HALF OF NEXT WEEK. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 735 PM EDT FRI AUG 22 2014 CLUSTERS OF THUNDERSTORMS WILL HEAVY RAINFALL WILL BE AFFECTING JKL AND SJS THROUGH 2 OR 3Z THIS EVENING. BASED ON CURRENT RADAR IMAGERY IT APPEARS THAT JKL WILL EXPERIENCE THE LONGEST DURATION OF THUNDERSTORM ACTIVITY THIS EVENING. THE PRIMARY HAZARDS TO FOCUS ON FOR TAF PURPOSES WILL BE LOCALLY HEAVY RAINFALL THAT COULD LEAD TO FLASH FLOODING AND FREQUENT IN CLOUD AND CLOUD TO GROUND LIGHTNING. IN GENERAL VFR CONDITIONS WILL BE EXPECTED OVERNIGHT...BUT ANY THUNDERSTORMS THAT AFFECT JKL OR SJS COULD LEAD TO MVFR TO PERHAPS IFR CONDITIONS DEPENDING ON HOW INTENSE THE RAIN AND WINDS WITH THESE STORMS ARE. THE STORMS SHOULD GRADUALLY DIE DOWN AS THE SUN CONTINUES TO SET...GIVING WAY TO SCATTERED RAIN SHOWERS AND PERHAPS AN ISOLATED RUMBLE OF THUNDER OVERNIGHT. THE NEXT ROUND OF MORE WIDESPREAD SHOWERS AND STORMS ARE EXPECTED TO AFFECT ALL OF THE TAF SITES FROM 15Z ONWARD ON SATURDAY. AS FOR TONIGHT...LOZ AND SME MIGHT BE SPARED THE BULK OF THUNDERSTORM ACTIVITY...BUT THIS WILL NEED TO BE MONITORED CLOSELY OVER THE NEXT FEW HOURS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...GREIF LONG TERM...KAS AVIATION...AR
AREA FORECAST DISCUSSION
NWS JACKSON KY
934 PM EDT FRI AUG 22 2014 .UPDATE... ISSUED AT 934 PM EDT FRI AUG 22 2014 JUST SENT OUT A QUICK UPDATE TO THE ZONE FORECAST. THE FORECAST GRIDS HAVE BEEN MODIFIED EXTENSIVELY OVER THE PAST COUPLE OF HOURS TO ACCOUNT FOR THE WIDESPREAD HEAVY RAINFALL PRODUCING THUNDERSTORMS THAT HAVE BEEN MOVING ACROSS THE AREA. THE PRIMARY AREAS OF CONCERN FOR THE NEXT COUPLE OF HOURS WILL BE PIKE...JOHNSON...AND FLOYD COUNTIES. SHOWERS AND THUNDERSTORMS ARE CONTINUING TO DECREASE IN COVERAGE ALONG THE VIRGINIA BORDER. ADDITIONAL SHOWERS AND STORMS WILL CONTINUE TO MOVE INTO EASTERN KENTUCKY FROM THE NORTHWEST OVERNIGHT. NUMEROUS REPORTS OF FLASH FLOODING HAVE BEEN RECEIVED OUT OF FLOYD...ESTILL...AND PIKE COUNTY SO FAR THIS EVENING. MANY REPORTS WILL LIKELY BE RECEIVED AS OUR 24 HOUR WARNING POINTS ARE ABLE TO RELAY THEM TO US. THE PRECIPITATION PROBABILITIES...SKY COVER...QPF...AND WEATHER TYPE GRIDS HAVE ALL BEEN UPDATED TO BETTER REFLECT REAL TIME WEATHER CONDITIONS ACROSS THE AREA. ANOTHER FORECAST UPDATE WILL BE SENT OUT BEFORE THE END OF THE SHIFT. UPDATE ISSUED AT 735 PM EDT FRI AUG 22 2014 MADE A FEW ADJUSTMENTS TO THE FORECAST GRIDS FOR THE REMAINDER OF THE OVERNIGHT PERIOD TO BETTER REPRESENT CURRENT CONDITIONS AND THE LATEST MODEL DATA. THE CHANGES WERE MADE TO PRECIPITATION PROBABILITIES...PRECIP AMOUNTS...AND WEATHER TYPE GRIDS. THESE CHANGES WERE MOSTLY COSMETIC AND SHOULD NOT CAUSE CHANGES TO THE ZONE FORECAST TEXT PRODUCT THAT WOULD WARRANT ISSUING A NEW FORECAST. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 335 PM EDT FRI AUG 22 2014 18Z SFC ANALYSIS SHOWS A CONVECTIVELY WASHED OUT BOUNDARY JUST NORTH OF THE OHIO RIVER. THIS LEADS BACK WEST TO A DEVELOPING AREA OF LOW PRESSURE OVER THE HIGH PLAINS. MEANWHILE...AN AREA OF HIGH PRESSURE IS FOUND THROUGH THE DEEP SOUTH. ALOFT...A FAIRLY STRONG RIDGE OF HIGH HEIGHTS STRETCHES FROM THE SOUTHERN PLAINS THROUGH THE LOWER MISSISSIPPI RIVER VALLEY AND ACROSS THE DEEP SOUTH WHILE TROUGHING IS FOUND OVER NEW ENGLAND. BETWEEN THESE UPPER LEVEL FEATURES...A COUPLE OF SHORTWAVES ARE PASSING BY TO THE NORTHEAST. THE LEADING ONE OF THESE IS RESPONSIBLE FOR BETTER DEVELOPMENT OF CONVECTION OVER FAR EASTERN KENTUCKY AND WESTERN WEST VIRGINIA. ELSEWHERE...TO THE WEST OF THIS AREA...A FEW SCATTERED SHOWERS AND THUNDERSTORMS ARE TAKING SHAPE ALONG AN OLD OUTFLOW BOUNDARY FROM THE PRE DAWN MCS THAT MOVED THROUGH OHIO EARLY THIS MORNING. WITH THE BULK OF THE ACTIVITY HOLDING OFF UNTIL LATER IN THE AFTERNOON...TEMPERATURES HAVE CLIMBED INTO THE UPPER 80S FOR MOST LOCATIONS WITH A FEW 90 DEGREE READINGS NOTED. DEWPOINTS IN THE LOWER AND MIDDLE 70S ARE MAKING FOR MISERABLE HEAT INDICES THROUGH THE AREA AND WILL BE PROVIDING FUEL FOR STORM DEVELOPMENT. WINDS ARE GENERALLY FROM THE WEST SOUTHWEST AT 5 TO 10 KTS WITH A FEW GUSTS TO 15 KTS. THE MODELS ARE IN GOOD AGREEMENT THROUGH THE SHORT TERM ALOFT AS THEY ALL WOBBLE AND WEAKEN SLIGHTLY THE RIDGE TO OUR WEST IN THE FACE OF THE NEW ENGLAND TROUGH DROPPING NEARLY DUE SOUTH TO THE MID ATLANTIC COAST BY SUNDAY MORNING. DESPITE THE MOVEMENT OF THESE LARGER FEATURES...THE TRACK OF SHORTWAVES WILL CONTINUE TO PASS THROUGH FAR EASTERN KENTUCKY...JUST ORIENTATED MORE NORTH TO SOUTH BY THE END OF THE PERIOD. GIVEN THE MODEL AGREEMENT AND THE SMALLER SCALE NATURE OF THE PERIODIC MCS ACTIVITY HAVE FAVORED THE HIGHER RESOLUTION MODELS LIKE THE HRRR AND NAM12 FOR THIS FORECAST. SENSIBLE WEATHER WILL FEATURE A THREAT OF STORMS INTO THE EVENING... PERHAPS LENGTHENED BY ANY DEVELOPMENT TO THE NORTHWEST THAT COULD MOVE INTO AT LEAST THE NORTHWEST PORTION OF THE JKL CWA AFTER DARK... PER THE LATEST HRRR. SIMILAR TO LAST EVENING...THE MAIN THREATS WITH ANY STORMS WILL BE GUSTY WINDS AND TORRENTIAL DOWNPOURS OF RAIN. AGAIN TONIGHT...WOULD ANTICIPATE PATCHY FOG THROUGH THE AREA AND THE POTENTIAL FOR DENSE SPOTS LOCALLY GIVEN ANY CLEARING. AFTER A MUGGY NIGHT...ANOTHER WARM AND HUMID DAY CAN BE EXPECTED FOR SATURDAY WITH MID LEVEL CHANCES OF SHOWERS AND THUNDERSTORMS THROUGH THE ENTIRETY WITH ONLY A SLIGHT FAVORING OF THE LATE AFTERNOON AND EARLY EVENING HOURS. HIGH PWS AND INSTABILITY DURING THE DAY WILL SET THE TABLE FOR A CONTINUED THREAT OF EXCESSIVE RAINFALL AND STRONG STORMS...THOUGH THE SEVERE RISK WILL BE LIMITED BY A GENERALLY BENIGN NORTHWEST WIND FIELD ALOFT. SIMILARLY...SATURDAY NIGHT WILL BE ANOTHER MUGGY AND WARM ONE WITH PATCHY FOG ANTICIPATED FOR PLACES THAT WOULD HAVE SEEN RAIN DURING THE DAY. CANNOT RULE OUT ADDITIONAL SHOWER AND STORM ACTIVITY INTO EARLY SUNDAY GIVEN THE UPPER LEVEL PATTERN AND NEARBY SFC BOUNDARIES. AGAIN USED THE CONSSHORT AS A STARTING POINT FOR THE T/TD/WINDS THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND SATURDAY NIGHT. AS FOR POPS...ENDED UP IN BETWEEN THE MAV AND THE WETTER MET GUIDANCE FOR MOST OF THE SHORT TERM PORTION OF THE FORECAST. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 255 PM EDT FRI AUG 22 2014 STRONG RIDGING WILL CONTINUE TO DEVELOP OVER THE EASTERN CONUS LATE IN THE WEEKEND THROUGH THE EARLY PART OF NEXT WEEK. AS THE CENTER OF THE HIGH PUSHES OVERHEAD EARLY NEXT WEEK...IT WILL SEND SOME SLIGHTLY DRIER AIR INTO EASTERN KENTUCKY...FINALLY BRINGING A TEMPORARY END TO THE RAIN CHANCES. HAVE BEEN GOING WITH LOW POPS EARLY NEXT WEEK...BUT GIVEN THE NATURE OF THE DRY AIR...HAVE OPTED TO GO WITH DRY WEATHER EARLY TO MIDDLE PART OF NEXT WEEK. IN FACT...DEWPOINTS MAY GET LOW ENOUGH TO WARRANT A FEW TEMPERATURES INTO THE LOWER AND MIDDLE 60S TUESDAY AND WEDNESDAY MORNINGS. CANNOT RULE OUT SOME SHOWERS ON SUNDAY OR SUNDAY EVENING PRIOR TO THE DEPARTURE OF THE BETTER MID LEVEL MOISTURE. HOWEVER...EVEN THIS ACTIVITY WILL LIKELY BE LESS THAN WHAT WE HAVE SEEN RECENTLY. THUS...OVERALL...LOOK FOR A QUIETER STRETCH OF WEATHER INTO THE MIDDLE OF NEXT WEEK. BY LATE IN THE PERIOD. THE RIDGE MAY BEGIN TO BREAK DOWN AS A SHORTWAVE TROUGH MOVING ACROSS THE GREAT LAKES PUSHES A BOUNDARY SOUTHWARD INTO THE OHIO RIVER VALLEY. TOO MUCH UNCERTAINTY WITH THIS BOUNDARY TO GO WITH ANYTHING MORE THAN CHANCE POPS FROM THURSDAY ONWARD. THE 00Z ECMWF HAD PUT THE BOUNDARY OVER EASTERN KENTUCKY...BUT THE 12Z RUN HAS KEPT IT TO THE NORTH THROUGH WEEKS END. IF THE BOUNDARY STAYS NORTH...PROBABLY GOING TO SEE WARMER AND HUMID CONDITIONS PERSISTING THROUGH THE SECOND HALF OF NEXT WEEK. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 735 PM EDT FRI AUG 22 2014 CLUSTERS OF THUNDERSTORMS WILL HEAVY RAINFALL WILL BE AFFECTING JKL AND SJS THROUGH 2 OR 3Z THIS EVENING. BASED ON CURRENT RADAR IMAGERY IT APPEARS THAT JKL WILL EXPERIENCE THE LONGEST DURATION OF THUNDERSTORM ACTIVITY THIS EVENING. THE PRIMARY HAZARDS TO FOCUS ON FOR TAF PURPOSES WILL BE LOCALLY HEAVY RAINFALL THAT COULD LEAD TO FLASH FLOODING AND FREQUENT IN CLOUD AND CLOUD TO GROUND LIGHTNING. IN GENERAL VFR CONDITIONS WILL BE EXPECTED OVERNIGHT...BUT ANY THUNDERSTORMS THAT AFFECT JKL OR SJS COULD LEAD TO MVFR TO PERHAPS IFR CONDITIONS DEPENDING ON HOW INTENSE THE RAIN AND WINDS WITH THESE STORMS ARE. THE STORMS SHOULD GRADUALLY DIE DOWN AS THE SUN CONTINUES TO SET...GIVING WAY TO SCATTERED RAIN SHOWERS AND PERHAPS AN ISOLATED RUMBLE OF THUNDER OVERNIGHT. THE NEXT ROUND OF MORE WIDESPREAD SHOWERS AND STORMS ARE EXPECTED TO AFFECT ALL OF THE TAF SITES FROM 15Z ONWARD ON SATURDAY. AS FOR TONIGHT...LOZ AND SME MIGHT BE SPARED THE BULK OF THUNDERSTORM ACTIVITY...BUT THIS WILL NEED TO BE MONITORED CLOSELY OVER THE NEXT FEW HOURS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...GREIF LONG TERM...KAS AVIATION...AR
AREA FORECAST DISCUSSION
NWS JACKSON KY
736 PM EDT FRI AUG 22 2014 .UPDATE... ISSUED AT 735 PM EDT FRI AUG 22 2014 MADE A FEW ADJUSTMENTS TO THE FORECAST GRIDS FOR THE REMAINDER OF THE OVERNIGHT PERIOD TO BETTER REPRESENT CURRENT CONDITIONS AND THE LATEST MODEL DATA. THE CHANGES WERE MADE TO PRECIPITATION PROBABILITIES...PRECIP AMOUNTS...AND WEATHER TYPE GRIDS. THESE CHANGES WERE MOSTLY COSMETIC AND SHOULD NOT CAUSE CHANGES TO THE ZONE FORECAST TEXT PRODUCT THAT WOULD WARRANT ISSUING A NEW FORECAST. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 335 PM EDT FRI AUG 22 2014 18Z SFC ANALYSIS SHOWS A CONVECTIVELY WASHED OUT BOUNDARY JUST NORTH OF THE OHIO RIVER. THIS LEADS BACK WEST TO A DEVELOPING AREA OF LOW PRESSURE OVER THE HIGH PLAINS. MEANWHILE...AN AREA OF HIGH PRESSURE IS FOUND THROUGH THE DEEP SOUTH. ALOFT...A FAIRLY STRONG RIDGE OF HIGH HEIGHTS STRETCHES FROM THE SOUTHERN PLAINS THROUGH THE LOWER MISSISSIPPI RIVER VALLEY AND ACROSS THE DEEP SOUTH WHILE TROUGHING IS FOUND OVER NEW ENGLAND. BETWEEN THESE UPPER LEVEL FEATURES...A COUPLE OF SHORTWAVES ARE PASSING BY TO THE NORTHEAST. THE LEADING ONE OF THESE IS RESPONSIBLE FOR BETTER DEVELOPMENT OF CONVECTION OVER FAR EASTERN KENTUCKY AND WESTERN WEST VIRGINIA. ELSEWHERE...TO THE WEST OF THIS AREA...A FEW SCATTERED SHOWERS AND THUNDERSTORMS ARE TAKING SHAPE ALONG AN OLD OUTFLOW BOUNDARY FROM THE PRE DAWN MCS THAT MOVED THROUGH OHIO EARLY THIS MORNING. WITH THE BULK OF THE ACTIVITY HOLDING OFF UNTIL LATER IN THE AFTERNOON...TEMPERATURES HAVE CLIMBED INTO THE UPPER 80S FOR MOST LOCATIONS WITH A FEW 90 DEGREE READINGS NOTED. DEWPOINTS IN THE LOWER AND MIDDLE 70S ARE MAKING FOR MISERABLE HEAT INDICES THROUGH THE AREA AND WILL BE PROVIDING FUEL FOR STORM DEVELOPMENT. WINDS ARE GENERALLY FROM THE WEST SOUTHWEST AT 5 TO 10 KTS WITH A FEW GUSTS TO 15 KTS. THE MODELS ARE IN GOOD AGREEMENT THROUGH THE SHORT TERM ALOFT AS THEY ALL WOBBLE AND WEAKEN SLIGHTLY THE RIDGE TO OUR WEST IN THE FACE OF THE NEW ENGLAND TROUGH DROPPING NEARLY DUE SOUTH TO THE MID ATLANTIC COAST BY SUNDAY MORNING. DESPITE THE MOVEMENT OF THESE LARGER FEATURES...THE TRACK OF SHORTWAVES WILL CONTINUE TO PASS THROUGH FAR EASTERN KENTUCKY...JUST ORIENTATED MORE NORTH TO SOUTH BY THE END OF THE PERIOD. GIVEN THE MODEL AGREEMENT AND THE SMALLER SCALE NATURE OF THE PERIODIC MCS ACTIVITY HAVE FAVORED THE HIGHER RESOLUTION MODELS LIKE THE HRRR AND NAM12 FOR THIS FORECAST. SENSIBLE WEATHER WILL FEATURE A THREAT OF STORMS INTO THE EVENING... PERHAPS LENGTHENED BY ANY DEVELOPMENT TO THE NORTHWEST THAT COULD MOVE INTO AT LEAST THE NORTHWEST PORTION OF THE JKL CWA AFTER DARK... PER THE LATEST HRRR. SIMILAR TO LAST EVENING...THE MAIN THREATS WITH ANY STORMS WILL BE GUSTY WINDS AND TORRENTIAL DOWNPOURS OF RAIN. AGAIN TONIGHT...WOULD ANTICIPATE PATCHY FOG THROUGH THE AREA AND THE POTENTIAL FOR DENSE SPOTS LOCALLY GIVEN ANY CLEARING. AFTER A MUGGY NIGHT...ANOTHER WARM AND HUMID DAY CAN BE EXPECTED FOR SATURDAY WITH MID LEVEL CHANCES OF SHOWERS AND THUNDERSTORMS THROUGH THE ENTIRETY WITH ONLY A SLIGHT FAVORING OF THE LATE AFTERNOON AND EARLY EVENING HOURS. HIGH PWS AND INSTABILITY DURING THE DAY WILL SET THE TABLE FOR A CONTINUED THREAT OF EXCESSIVE RAINFALL AND STRONG STORMS...THOUGH THE SEVERE RISK WILL BE LIMITED BY A GENERALLY BENIGN NORTHWEST WIND FIELD ALOFT. SIMILARLY...SATURDAY NIGHT WILL BE ANOTHER MUGGY AND WARM ONE WITH PATCHY FOG ANTICIPATED FOR PLACES THAT WOULD HAVE SEEN RAIN DURING THE DAY. CANNOT RULE OUT ADDITIONAL SHOWER AND STORM ACTIVITY INTO EARLY SUNDAY GIVEN THE UPPER LEVEL PATTERN AND NEARBY SFC BOUNDARIES. AGAIN USED THE CONSSHORT AS A STARTING POINT FOR THE T/TD/WINDS THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND SATURDAY NIGHT. AS FOR POPS...ENDED UP IN BETWEEN THE MAV AND THE WETTER MET GUIDANCE FOR MOST OF THE SHORT TERM PORTION OF THE FORECAST. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 255 PM EDT FRI AUG 22 2014 STRONG RIDGING WILL CONTINUE TO DEVELOP OVER THE EASTERN CONUS LATE IN THE WEEKEND THROUGH THE EARLY PART OF NEXT WEEK. AS THE CENTER OF THE HIGH PUSHES OVERHEAD EARLY NEXT WEEK...IT WILL SEND SOME SLIGHTLY DRIER AIR INTO EASTERN KENTUCKY...FINALLY BRINGING A TEMPORARY END TO THE RAIN CHANCES. HAVE BEEN GOING WITH LOW POPS EARLY NEXT WEEK...BUT GIVEN THE NATURE OF THE DRY AIR...HAVE OPTED TO GO WITH DRY WEATHER EARLY TO MIDDLE PART OF NEXT WEEK. IN FACT...DEWPOINTS MAY GET LOW ENOUGH TO WARRANT A FEW TEMPERATURES INTO THE LOWER AND MIDDLE 60S TUESDAY AND WEDNESDAY MORNINGS. CANNOT RULE OUT SOME SHOWERS ON SUNDAY OR SUNDAY EVENING PRIOR TO THE DEPARTURE OF THE BETTER MID LEVEL MOISTURE. HOWEVER...EVEN THIS ACTIVITY WILL LIKELY BE LESS THAN WHAT WE HAVE SEEN RECENTLY. THUS...OVERALL...LOOK FOR A QUIETER STRETCH OF WEATHER INTO THE MIDDLE OF NEXT WEEK. BY LATE IN THE PERIOD. THE RIDGE MAY BEGIN TO BREAK DOWN AS A SHORTWAVE TROUGH MOVING ACROSS THE GREAT LAKES PUSHES A BOUNDARY SOUTHWARD INTO THE OHIO RIVER VALLEY. TOO MUCH UNCERTAINTY WITH THIS BOUNDARY TO GO WITH ANYTHING MORE THAN CHANCE POPS FROM THURSDAY ONWARD. THE 00Z ECMWF HAD PUT THE BOUNDARY OVER EASTERN KENTUCKY...BUT THE 12Z RUN HAS KEPT IT TO THE NORTH THROUGH WEEKS END. IF THE BOUNDARY STAYS NORTH...PROBABLY GOING TO SEE WARMER AND HUMID CONDITIONS PERSISTING THROUGH THE SECOND HALF OF NEXT WEEK. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 735 PM EDT FRI AUG 22 2014 CLUSTERS OF THUNDERSTORMS WILL HEAVY RAINFALL WILL BE AFFECTING JKL AND SJS THROUGH 2 OR 3Z THIS EVENING. BASED ON CURRENT RADAR IMAGERY IT APPEARS THAT JKL WILL EXPERIENCE THE LONGEST DURATION OF THUNDERSTORM ACTIVITY THIS EVENING. THE PRIMARY HAZARDS TO FOCUS ON FOR TAF PURPOSES WILL BE LOCALLY HEAVY RAINFALL THAT COULD LEAD TO FLASH FLOODING AND FREQUENT IN CLOUD AND CLOUD TO GROUND LIGHTNING. IN GENERAL VFR CONDITIONS WILL BE EXPECTED OVERNIGHT...BUT ANY THUNDERSTORMS THAT AFFECT JKL OR SJS COULD LEAD TO MVFR TO PERHAPS IFR CONDITIONS DEPENDING ON HOW INTENSE THE RAIN AND WINDS WITH THESE STORMS ARE. THE STORMS SHOULD GRADUALLY DIE DOWN AS THE SUN CONTINUES TO SET...GIVING WAY TO SCATTERED RAIN SHOWERS AND PERHAPS AN ISOLATED RUMBLE OF THUNDER OVERNIGHT. THE NEXT ROUND OF MORE WIDESPREAD SHOWERS AND STORMS ARE EXPECTED TO AFFECT ALL OF THE TAF SITES FROM 15Z ONWARD ON SATURDAY. AS FOR TONIGHT...LOZ AND SME MIGHT BE SPARED THE BULK OF THUNDERSTORM ACTIVITY...BUT THIS WILL NEED TO BE MONITORED CLOSELY OVER THE NEXT FEW HOURS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...GREIF LONG TERM...KAS AVIATION...AR
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
355 PM EDT THU AUG 21 2014 .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 355 PM EDT THU AUG 21 2014 19Z SFC ANALYSIS SHOWS A SEASONALLY STRONG AREA OF LOW PRESSURE OVER THE HIGH PLAINS WITH HIGH PRESSURE OVER THE DEEP SOUTH. THIS NEARBY HIGH IS NOT ENOUGH TO PREVENT THE LATEST INCARNATION OF MCS ACTIVITY FROM DIVING THROUGH EASTERN KENTUCKY. THIS IS TAKING ADVANTAGE OF HIGH INSTABILITY THROUGHOUT THE AREA GIVEN TEMPERATURES IN THE UPPER 80S AND DEWPOINTS IN THE LOWER 70S. IN ADDITION TO THE SEVERE THUNDERSTORM THREAT...HIGH PWS...LOW FFG...AND A POTENTIAL FOR TRAINING WILL KEEP FLASH FLOODING A CONCERN THROUGH THE EVENING. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM PORTION OF THE FORECAST WITH A LARGE AREA OF RIDGING STRETCHING FROM THE LOWER MISSISSIPPI VALLEY INTO THE TENNESSEE VALLEY. AS IT DOES SO...A DEEP LOW TO THE NORTHEAST WILL SEND PACKETS OF ENERGY THROUGH THE OHIO VALLEY AND INTO THE CENTRAL APPALACHIANS IN FAIRLY FAST NORTHWEST FLOW. THIS WILL PLACE AT LEAST NORTHEAST PARTS OF THE JKL CWA IN THE STORM TRACK AND AS PRIME REAL ESTATE FOR MCS ACTIVITY. GIVEN THE MODEL AGREEMENT HAVE FAVORED A BLEND WITH EXTRA EMPHASIS ON THE HRRR AND NAM12 FOR THE FIRST 12 TO 24 HOURS. SENSIBLE WEATHER WILL FEATURE ON GOING THUNDERSTORM ACTIVITY DIMINISHING INTO THE EVENING...BUT PROGRESSING SOUTH WITH THE FAVORED INSTABILITY. LATER TONIGHT...PARTLY CLOUDS SKIES AND THE MOISTURE FROM THE RAIN OF THIS AFTERNOON AND EVENING WILL LIKELY LEAD TO AREAS OF FOG...LOCALLY DENSE. INDICATIONS ARE THAT THE NEXT ROUND OF STORMS STAY TO THE NORTHEAST OF THE CWA TONIGHT. AFTER THE FOG BURNS OFF ON FRIDAY MORNING THE INSTABILITY WILL BUILD AGAIN WITH ANOTHER VERY HUMID AND WARM DAY. THIS WILL BE A SIMILAR SETUP FOR SEVERE AND EXCESSIVE RAIN POTENTIAL...MAINLY IN THE NORTHEAST BASED ON THE EXPECTATION OF EARLY STORMS TRACKING JUST OUTSIDE OF THE CWA AND DEVELOPMENT ON THEIR SOUTHWEST FLANKS. LIKEWISE...PATCHY FOG WILL BE AN ISSUE FOR THE AREA LATER FRIDAY NIGHT GIVEN A SIMILAR SETUP... BUT STILL DEPENDENT ON THE RAINS EARLY IN THE DAY AND EVENING. USED THE CONSSHORT AS A STARTING POINT FOR THE T...TD...AND WINDS THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND FRIDAY NIGHT. AS FOR POPS...ENDED UP HIGHER THAN GUIDANCE...EXCEPT FOR THE MET NORTH OF JKL ON FRIDAY NIGHT...THROUGH SATURDAY MORNING OWING TO THE TENDENCY FOR STORMS TO EXPAND SOUTHWEST OF THEIR DEPICTIONS IN THE MODELS. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 315 PM EDT THU AUG 21 2014 STRONG RIDGING WILL LIKELY HOLD OVER THE AREA FOR THE BALANCE OF THE EXTENDED PART OF THE FORECAST. SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE EACH DAY THROUGH THE MIDDLE OF NEXT WEEK. IN ADDITION...WARM AND MUGGY CONDITIONS WILL REMAIN ANCHORED BENEATH THE RIDGE. BEST TIME FOR SHOWERS AND STORMS WILL CONTINUE TO BE EACH AFTERNOON/EVENING...BUT CANNOT RULE OUT AN ISOLATED SHOWER OR STORM AT ANY TIME INTO NEXT WEEK. GFS MOS IS LIKELY A BIT TOO HIGH AND WILL CONTINUE TO GO BETWEEN GFS AND MET MOS THROUGH SATURDAY. ECMWF SEEMS TO BE A GOOD COMPROMISE WITH REGARDS TO TEMPERATURES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 210 PM EDT THU AUG 21 2014 THE AVIATION FORECAST WILL BE A CHALLENGE WITH THE TIMING OF MCS CLUSTERS AND POTENTIAL FOR FOG FORMATION THROUGH THE PERIOD. EXPECT THE BETTER CHANCES FOR LOWER CIGS AND VIS ASSOCIATED WITH STORMS WILL BE FOR THE NORTHERN TAF SITES THROUGH EARLY EVENING. THESE LOCATIONS MAY HAVE A BETTER CHANCE FOR MORE IN THE WAY OF LOWER VIS PRODUCING FOG. HOWEVER...THAT WILL BE DEPENDENT ON ADDED MOISTURE FROM CONVECTION DURING THE REST OF THE DAY AND SOME CLEARING LATER TONIGHT. FOR NOW...HAVE BROUGHT ALL THE SITES TO MVFR IN BR AFTER 06Z AND CLEARING OUT...BACK TO VFR BY 14Z FRIDAY. CANNOT RULE OUT ADDITIONAL STORMS FRIDAY AFTERNOON...ESPECIALLY NORTHEAST...BUT THROUGH 18Z THE TAF SITES SHOULD REMAIN CALM. WINDS THROUGH THE NIGHT WILL BE LIGHT AND VARIABLE...FAVORING THE SOUTHWEST AT 5 TO 10 KTS DURING THE DAYLIGHT HOURS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...KAS AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
210 PM EDT THU AUG 21 2014 .UPDATE... ISSUED AT 140 PM EDT THU AUG 21 2014 WITH AN AREA OF SCATTERED STORMS NOW MOVING EAST ALONG INTERSTATE 64 HAVE UPDATED THE FORECAST TO REFLECT THE HIGHER POPS NORTH OF THE MOUNTAIN PARKWAY AND LOWER TEMPS THERE. ALSO ADDED MORE POPS IN THE HIGHER TERRAIN OVER THE FAR SOUTHEAST AND LOWERED THEM ELSEWHERE FOR THE NEXT FEW HOURS. AFTER THAT...OUTFLOWS FROM THE NORTHERN STORMS WILL POTENTIALLY BRING CONVECTIVE DEVELOPMENT FURTHER SOUTH...AIDED BY THE HIGHER INSTABILITY. IN ADDITION...MADE SOME TWEAKS TO THE HOURLY TEMPS AND DEWPOINTS FOR THE REST OF THE AFTERNOON GIVEN THE CURRENT OBS AND TRENDS. THESE UPDATED GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. UPDATE ISSUED AT 1050 AM EDT THU AUG 21 2014 14Z SFC ANALYSIS SHOW GENERAL LOW PRESSURE NORTH OF THE OHIO RIVER WITH HIGHER PRESSURE FOUND TO THE SOUTH. A STATIONARY BOUNDARY EXISTS THROUGH THE NORTHERN PORTIONS OF THE OHIO VALLEY AND WESTERN PARTS OF THIS FRONT...CONNECTED BACK TO DEEPER LOW PRESSURE OVER THE NORTHERN PLAINS...HAS BEEN A GENESIS REGION FOR RECENT MCS ACTIVITY. THIS ACTIVITY IS ALSO SUPPORTED BY A STREAM OF MID LEVEL ENERGY RIDING ALONG THE NORTHERN FRINGE OF A DEVELOPING RIDGE TO THE SOUTHWEST OF KENTUCKY. THIS WOULD TEND TO SUPPORT CONVECTION WORKING SOUTHEAST FROM THE UPPER MIDWEST TO THE CENTRAL APPALACHIANS PASSING BY JUST TO OUR NORTHEAST. HOWEVER...INSTABILITY BUILDING WITH THE RECENT ARRIVAL OF SUMMER TIME HEAT AND HUMIDITY ACROSS KENTUCKY WILL BE ENOUGH TO KEEP A THREAT OF THE STORMS AND THEIR OUTFLOW BOUNDARIES SNEAKING INTO NORTHEAST PORTIONS OF THE CWA AND PERHAPS FURTHER TO THE SOUTHWEST IN THE AFTERNOON. THE CURRENT RADAR HAS A HEALTHY CLUSTER OF STORMS CROSSING FROM INDIANA INTO OHIO WITH A GROWING SOUTHERN EXTENT TRACKING THROUGH NORTHERN KENTUCKY. EXPECT THIS TO BRUSH INTO NORTHERN PARTS OF THE FORECAST AREA THROUGH THE NEXT SEVERAL HOURS. THE HRRR KEEPS THIS FIRST WAVE JUST NORTH OF THE CWA...WHILE THE 12Z NAM12 DIPS THE CONVECTION DEEPER INTO EAST KENTUCKY. FOR THIS UPDATE HAVE SPLIT THE DIFFERENCE BETWEEN THESE TWO SCENARIOS AND PEAKED POPS IN THE NORTHEAST THROUGH THE AFTERNOON WITH SOME SMALL TO MODERATE POPS EVEN DOWN INTO THE CUMBERLAND VALLEY BY EVENING. HIGH PWS AND THE RAINS OF THE PAST SEVERAL DAYS WILL MEAN A THREAT OF FLASH FLOODING FOR PLACES THAT SEE REPEATED STORMS... PARTICULARLY THROUGH THE MID SECTION OF THE CWA. SPC HAS PLACED EASTERN PARTS OF THE AREA...ALONG THE PREVIOUSLY DISCUSSED STORM TRACK...IN A SLIGHT RISK FOR SEVERE WEATHER...MAINLY DAMAGING WINDS AND LARGE HAIL. THIS APPEARS REASONABLE GIVEN THE HIGH CAPE...LOW LIS...AND LACK OF A MID LEVEL CAP. ACCORDINGLY THIS CONCERN WILL CONTINUE TO BE HIGHLIGHTED IN THE HWO ALONG WITH A MENTION OF THE HEAT AND HUMIDITY...TEMPS NEAR 90 AND DEWPOINTS IN THE 70S...THROUGH THE WEEKEND. HAVE ALSO FINE TUNED THE T AND TD GRIDS PER THE LATEST OBS...TRENDS...AND CONSSHORT GUIDANCE. THESE UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS WITH NEW HWO AND ZONES ON THEIR WAY. UPDATE ISSUED AT 757 AM EDT THU AUG 21 2014 THE FORECAST REMAINS ON TRACK THIS MORNING. FRESHENED UP THE HOURLY TEMPERATURES...DEW POINTS...AND SKY COVER TO ACCOUNT FOR THE LATEST TRENDS IN THE OBSERVATIONS. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 357 AM EDT THU AUG 21 2014 THE LATEST SURFACE MAP FEATURES HIGH PRESSURE ACROSS THE GULF COAST STATES...WITH LOW PRESSURE ACROSS THE PLAINS STATES. A STATIONARY BOUNDARY EXTENDS EAST FROM THE PLAINS INTO THE GREAT LAKES/OHIO VALLEY REGION. ALOFT...AN UPPER LEVEL LOW CONTINUES TO SPIN ACROSS THE NORTHERN GREAT LAKES...WITH AN UPPER LEVEL RIDGE CENTERED NEAR THE NORTHERN GULF OF MEXICO...AND MORE TROUGHING FEATURED ACROSS THE NORTHERN ROCKIES. SEVERAL COMPLEXES OF THUNDERSTORMS HAVE BEEN GENERATING AND THEN RIDING SOUTHEAST ON THE PERIPHERY OF THE UPPER LEVEL RIDGE OVER THE PAST FEW DAYS. CURRENTLY...EASTERN KENTUCKY REMAINS QUIET AS ONLY A WEAKENING SMALLER COMPLEX OF THUNDERSTORMS IS SLOWLY MOVING THROUGH SOUTHEAST ILLINOIS AND SOUTHWEST INDIANA. THE NEXT MORE ORGANIZED COMPLEX IS CURRENTLY MOVING THROUGH MINNESOTA. THE MODEL GUIDANCE HAS BEEN ALL OVER THE PLACE WITH THE TIMING OF THE MORE ORGANIZED CONVECTION AS OF LATE. AS SUCH...HAVE USED A GENERAL BLEND OF THE GUIDANCE AND THE INHERITED FORECAST. AS THE UPPER LEVEL RIDGE SLOWLY BUILDS INTO THE REGION THROUGH FRIDAY...IT WILL GENERALLY NUDGE THE MCS TRACK FURTHER NORTHEAST...HOWEVER SINCE THERE WILL BE PLENTY OF FUEL FOR THE STORMS AND A WEAK SYNOPTIC PATTERN IN PLACE...CAN NOT RULE OUT OUTFLOW INFLUENCE FURTHER SOUTHWEST. SOME STORMS COULD APPROACH SEVERE LIMITS...AND ISOLATED FLASH FLOODING WILL ALSO BE A POSSIBILITY...ESPECIALLY WHERE STORMS CAN MOVE PARALLEL TO ANY ESTABLISHED OUTFLOW BOUNDARIES. WILL HIGHLIGHT THESE THREATS IN THE HWO. POPS WILL GENERALLY PEAK IN THE AFTERNOON HOURS TODAY AND FRIDAY...WITH LESSER CHANCES DURING THE OVERNIGHT HOURS. HIGHS TODAY WILL AVERAGE IN THE 85 TO 90 DEGREE RANGE...WITH AROUND 90 DEGREES EXPECTED FOR MOST LOCATIONS ON FRIDAY. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 357 AM EDT THU AUG 21 2014 THE EXTENDED PORTION OF THE FORECAST BEGINS ON FRIDAY NIGHT WITH A WELL DEVELOPED MID LEVEL RIDGE CENTERED OVER THE MID WEST AND LONGWAVE TROUGH ENTERING THE NORTHWEST WITH AN EXITING TROUGH OVER THE NORTHEAST. THE MID LEVEL RIDGE AXIS EVENTUALLY SHIFTS EAST OVER THE OH VALLEY BY MONDAY AS IT WEAKENS A BIT WITH THE APPROACHING TROUGH OVER THE NORTHERN PLAINS AND THE TROUGH OVER THE NORTHEAST EXITING INTO THE ATLANTIC. THIS PATTERN BASICALLY KEEPS THE RIDGE OVER EASTERN KENTUCKY THROUGH THE REST OF THE EXTENDED. WITH THIS PATTERN IN PLACE THROUGH SUNDAY...EASTERN KENTUCKY REMAINS IN NORTHWEST FLOW WITH STILL A FEW MCS/S LIKELY POISED TO TRACK SOUTHEAST INTO THE AREA FOR THIS WEEKEND. WHILE MODELS INHERENTLY WILL HAVE TROUBLE TRACKING THEM...THE FIRST ONE SHOULD BE MOVING THROUGH FRIDAY NIGHT WITH THE NEXT ONE POSSIBLY SATURDAY NIGHT. BY SUNDAY...THE RIDGE AXIS REALLY BEGINS TO SET IN AND ADDITIONAL STRONG CONVECTION MAY BE LESS LIKELY AND MAY BE MORE TIED TO DIURNAL PROCESSES WITH A STATIONARY BOUNDARY ALONG THE EASTERN PORTION OF THE CWA. BY MONDAY AND THROUGH WEDNESDAY...THE MID LEVEL RIDGE AXIS MOVES OVER THE AREA WHICH SHOULD EFFECTIVELY CUT OFF CONVECTION...AT LEAST DEEP CONVECTION. SOME AFTERNOON SHOWERS AND POSSIBLY A STORM OR TWO MAY DEVELOP UNDER THE RIDGE. THE SOLUTION OF THE ALL MODEL BLEND WOULD SUGGEST SOME UNCERTAINTY THERE WITH THE BEST CHANCE OF PRECIP FRIDAY NIGHT THROUGH SUNDAY. THIS IS IN GOOD AGREEMENT WITH THE GFS AND EURO AS WELL. OVERALL THE BROAD BRUSH OF POPS THROUGH THE FIRST 3 DAYS OF THE EXTENDED SEEMS NEEDED DUE TO THE NATURE OF THE MODELS HAVING TROUBLE DEPICTING THE COMPLEXES MOVING THROUGH BUT DID GO WITH SOME DIURNAL CHARACTERISTICS. BY THE END OF THE EXTENDED...THE MODELS SEEM TO HINT AT THE RIDGE MOVING FARTHER EAST AS A STRONG SHORTWAVE AND ASSOCIATED COLD FRONT SEEMS POISED TO MOVE THROUGH THE MS RIVER VALLEY AND INTO THE OH VALLEY. IN ADDITION...THE WARM AND MUGGY WEATHER STILL LOOKS TO BE ON TAP THROUGH THE WEEKEND WITH HIGHS AROUND 90 THROUGH MONDAY AND DEW POINTS AROUND 70. THE END OF THE EXTENDED DOES SHOW SOME RELIEF FROM THE WARM AND HUMID WEATHER WITH THE APPROACH OF THE AFOREMENTIONED COLD FRONT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 210 PM EDT THU AUG 21 2014 THE AVIATION FORECAST WILL BE A CHALLENGE WITH THE TIMING OF MCS CLUSTERS AND POTENTIAL FOR FOG FORMATION THROUGH THE PERIOD. EXPECT THE BETTER CHANCES FOR LOWER CIGS AND VIS ASSOCIATED WITH STORMS WILL BE FOR THE NORTHERN TAF SITES THROUGH EARLY EVENING. THESE LOCATIONS MAY HAVE A BETTER CHANCE FOR MORE IN THE WAY OF LOWER VIS PRODUCING FOG. HOWEVER...THAT WILL BE DEPENDENT ON ADDED MOISTURE FROM CONVECTION DURING THE REST OF THE DAY AND SOME CLEARING LATER TONIGHT. FOR NOW...HAVE BROUGHT ALL THE SITES TO MVFR IN BR AFTER 06Z AND CLEARING OUT...BACK TO VFR BY 14Z FRIDAY. CANNOT RULE OUT ADDITIONAL STORMS FRIDAY AFTERNOON...ESPECIALLY NORTHEAST...BUT THROUGH 18Z THE TAF SITES SHOULD REMAIN CALM. WINDS THROUGH THE NIGHT WILL BE LIGHT AND VARIABLE...FAVORING THE SOUTHWEST AT 5 TO 10 KTS DURING THE DAYLIGHT HOURS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GEOGERIAN LONG TERM...SHALLENBERGER AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
1050 AM EDT THU AUG 21 2014 .UPDATE... ISSUED AT 1050 AM EDT THU AUG 21 2014 14Z SFC ANALYSIS SHOW GENERAL LOW PRESSURE NORTH OF THE OHIO RIVER WITH HIGHER PRESSURE FOUND TO THE SOUTH. A STATIONARY BOUNDARY EXISTS THROUGH THE NORTHERN PORTIONS OF THE OHIO VALLEY AND WESTERN PARTS OF THIS FRONT...CONNECTED BACK TO DEEPER LOW PRESSURE OVER THE NORTHERN PLAINS...HAS BEEN A GENESIS REGION FOR RECENT MCS ACTIVITY. THIS ACTIVITY IS ALSO SUPPORTED BY A STREAM OF MID LEVEL ENERGY RIDING ALONG THE NORTHERN FRINGE OF A DEVELOPING RIDGE TO THE SOUTHWEST OF KENTUCKY. THIS WOULD TEND TO SUPPORT CONVECTION WORKING SOUTHEAST FROM THE UPPER MIDWEST TO THE CENTRAL APPALACHIANS PASSING BY JUST TO OUR NORTHEAST. HOWEVER...INSTABILITY BUILDING WITH THE RECENT ARRIVAL OF SUMMER TIME HEAT AND HUMIDITY ACROSS KENTUCKY WILL BE ENOUGH TO KEEP A THREAT OF THE STORMS AND THEIR OUTFLOW BOUNDARIES SNEAKING INTO NORTHEAST PORTIONS OF THE CWA AND PERHAPS FURTHER TO THE SOUTHWEST IN THE AFTERNOON. THE CURRENT RADAR HAS A HEALTHY CLUSTER OF STORMS CROSSING FROM INDIANA INTO OHIO WITH A GROWING SOUTHERN EXTENT TRACKING THROUGH NORTHERN KENTUCKY. EXPECT THIS TO BRUSH INTO NORTHERN PARTS OF THE FORECAST AREA THROUGH THE NEXT SEVERAL HOURS. THE HRRR KEEPS THIS FIRST WAVE JUST NORTH OF THE CWA...WHILE THE 12Z NAM12 DIPS THE CONVECTION DEEPER INTO EAST KENTUCKY. FOR THIS UPDATE HAVE SPLIT THE DIFFERENCE BETWEEN THESE TWO SCENARIOS AND PEAKED POPS IN THE NORTHEAST THROUGH THE AFTERNOON WITH SOME SMALL TO MODERATE POPS EVEN DOWN INTO THE CUMBERLAND VALLEY BY EVENING. HIGH PWS AND THE RAINS OF THE PAST SEVERAL DAYS WILL MEAN A THREAT OF FLASH FLOODING FOR PLACES THAT SEE REPEATED STORMS... PARTICULARLY THROUGH THE MID SECTION OF THE CWA. SPC HAS PLACED EASTERN PARTS OF THE AREA...ALONG THE PREVIOUSLY DISCUSSED STORM TRACK...IN A SLIGHT RISK FOR SEVERE WEATHER...MAINLY DAMAGING WINDS AND LARGE HAIL. THIS APPEARS REASONABLE GIVEN THE HIGH CAPE...LOW LIS...AND LACK OF A MID LEVEL CAP. ACCORDINGLY THIS CONCERN WILL CONTINUE TO BE HIGHLIGHTED IN THE HWO ALONG WITH A MENTION OF THE HEAT AND HUMIDITY...TEMPS NEAR 90 AND DEWPOINTS IN THE 70S...THROUGH THE WEEKEND. HAVE ALSO FINE TUNED THE T AND TD GRIDS PER THE LATEST OBS...TRENDS...AND CONSSHORT GUIDANCE. THESE UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS WITH NEW HWO AND ZONES ON THEIR WAY. UPDATE ISSUED AT 757 AM EDT THU AUG 21 2014 THE FORECAST REMAINS ON TRACK THIS MORNING. FRESHENED UP THE HOURLY TEMPERATURES...DEW POINTS...AND SKY COVER TO ACCOUNT FOR THE LATEST TRENDS IN THE OBSERVATIONS. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 357 AM EDT THU AUG 21 2014 THE LATEST SURFACE MAP FEATURES HIGH PRESSURE ACROSS THE GULF COAST STATES...WITH LOW PRESSURE ACROSS THE PLAINS STATES. A STATIONARY BOUNDARY EXTENDS EAST FROM THE PLAINS INTO THE GREAT LAKES/OHIO VALLEY REGION. ALOFT...AN UPPER LEVEL LOW CONTINUES TO SPIN ACROSS THE NORTHERN GREAT LAKES...WITH AN UPPER LEVEL RIDGE CENTERED NEAR THE NORTHERN GULF OF MEXICO...AND MORE TROUGHING FEATURED ACROSS THE NORTHERN ROCKIES. SEVERAL COMPLEXES OF THUNDERSTORMS HAVE BEEN GENERATING AND THEN RIDING SOUTHEAST ON THE PERIPHERY OF THE UPPER LEVEL RIDGE OVER THE PAST FEW DAYS. CURRENTLY...EASTERN KENTUCKY REMAINS QUIET AS ONLY A WEAKENING SMALLER COMPLEX OF THUNDERSTORMS IS SLOWLY MOVING THROUGH SOUTHEAST ILLINOIS AND SOUTHWEST INDIANA. THE NEXT MORE ORGANIZED COMPLEX IS CURRENTLY MOVING THROUGH MINNESOTA. THE MODEL GUIDANCE HAS BEEN ALL OVER THE PLACE WITH THE TIMING OF THE MORE ORGANIZED CONVECTION AS OF LATE. AS SUCH...HAVE USED A GENERAL BLEND OF THE GUIDANCE AND THE INHERITED FORECAST. AS THE UPPER LEVEL RIDGE SLOWLY BUILDS INTO THE REGION THROUGH FRIDAY...IT WILL GENERALLY NUDGE THE MCS TRACK FURTHER NORTHEAST...HOWEVER SINCE THERE WILL BE PLENTY OF FUEL FOR THE STORMS AND A WEAK SYNOPTIC PATTERN IN PLACE...CAN NOT RULE OUT OUTFLOW INFLUENCE FURTHER SOUTHWEST. SOME STORMS COULD APPROACH SEVERE LIMITS...AND ISOLATED FLASH FLOODING WILL ALSO BE A POSSIBILITY...ESPECIALLY WHERE STORMS CAN MOVE PARALLEL TO ANY ESTABLISHED OUTFLOW BOUNDARIES. WILL HIGHLIGHT THESE THREATS IN THE HWO. POPS WILL GENERALLY PEAK IN THE AFTERNOON HOURS TODAY AND FRIDAY...WITH LESSER CHANCES DURING THE OVERNIGHT HOURS. HIGHS TODAY WILL AVERAGE IN THE 85 TO 90 DEGREE RANGE...WITH AROUND 90 DEGREES EXPECTED FOR MOST LOCATIONS ON FRIDAY. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 357 AM EDT THU AUG 21 2014 THE EXTENDED PORTION OF THE FORECAST BEGINS ON FRIDAY NIGHT WITH A WELL DEVELOPED MID LEVEL RIDGE CENTERED OVER THE MID WEST AND LONGWAVE TROUGH ENTERING THE NORTHWEST WITH AN EXITING TROUGH OVER THE NORTHEAST. THE MID LEVEL RIDGE AXIS EVENTUALLY SHIFTS EAST OVER THE OH VALLEY BY MONDAY AS IT WEAKENS A BIT WITH THE APPROACHING TROUGH OVER THE NORTHERN PLAINS AND THE TROUGH OVER THE NORTHEAST EXITING INTO THE ATLANTIC. THIS PATTERN BASICALLY KEEPS THE RIDGE OVER EASTERN KENTUCKY THROUGH THE REST OF THE EXTENDED. WITH THIS PATTERN IN PLACE THROUGH SUNDAY...EASTERN KENTUCKY REMAINS IN NORTHWEST FLOW WITH STILL A FEW MCS/S LIKELY POISED TO TRACK SOUTHEAST INTO THE AREA FOR THIS WEEKEND. WHILE MODELS INHERENTLY WILL HAVE TROUBLE TRACKING THEM...THE FIRST ONE SHOULD BE MOVING THROUGH FRIDAY NIGHT WITH THE NEXT ONE POSSIBLY SATURDAY NIGHT. BY SUNDAY...THE RIDGE AXIS REALLY BEGINS TO SET IN AND ADDITIONAL STRONG CONVECTION MAY BE LESS LIKELY AND MAY BE MORE TIED TO DIURNAL PROCESSES WITH A STATIONARY BOUNDARY ALONG THE EASTERN PORTION OF THE CWA. BY MONDAY AND THROUGH WEDNESDAY...THE MID LEVEL RIDGE AXIS MOVES OVER THE AREA WHICH SHOULD EFFECTIVELY CUT OFF CONVECTION...AT LEAST DEEP CONVECTION. SOME AFTERNOON SHOWERS AND POSSIBLY A STORM OR TWO MAY DEVELOP UNDER THE RIDGE. THE SOLUTION OF THE ALL MODEL BLEND WOULD SUGGEST SOME UNCERTAINTY THERE WITH THE BEST CHANCE OF PRECIP FRIDAY NIGHT THROUGH SUNDAY. THIS IS IN GOOD AGREEMENT WITH THE GFS AND EURO AS WELL. OVERALL THE BROAD BRUSH OF POPS THROUGH THE FIRST 3 DAYS OF THE EXTENDED SEEMS NEEDED DUE TO THE NATURE OF THE MODELS HAVING TROUBLE DEPICTING THE COMPLEXES MOVING THROUGH BUT DID GO WITH SOME DIURNAL CHARACTERISTICS. BY THE END OF THE EXTENDED...THE MODELS SEEM TO HINT AT THE RIDGE MOVING FARTHER EAST AS A STRONG SHORTWAVE AND ASSOCIATED COLD FRONT SEEMS POISED TO MOVE THROUGH THE MS RIVER VALLEY AND INTO THE OH VALLEY. IN ADDITION...THE WARM AND MUGGY WEATHER STILL LOOKS TO BE ON TAP THROUGH THE WEEKEND WITH HIGHS AROUND 90 THROUGH MONDAY AND DEW POINTS AROUND 70. THE END OF THE EXTENDED DOES SHOW SOME RELIEF FROM THE WARM AND HUMID WEATHER WITH THE APPROACH OF THE AFOREMENTIONED COLD FRONT. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 757 AM EDT THU AUG 21 2014 IFR OR WORSE FOG/STRATUS WILL DISSIPATE BY AROUND 13Z. SCATTERED TO NUMEROUS CONVECTION WILL LIKELY THREATEN ONCE AGAIN FROM 16Z THROUGH EARLY THIS EVENING. TIMING THIS ACTIVITY CONTINUES TO BE VERY CHALLENGING SO WILL KEEP VCTS WORDING ONLY AT THIS TIME. SOME MVFR OR WORSE FOG WILL LIKELY BE SEEN ONCE AGAIN AFTER 04Z TONIGHT. WINDS OF AROUND 5 KTS OR LESS WILL REMAIN OUT OF THE SOUTHWEST THROUGH THE PERIOD AS WELL. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GEOGERIAN LONG TERM...SHALLENBERGER AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS PADUCAH KY
639 AM CDT Thu Aug 21 2014 .UPDATE... Issued at 517 AM CDT THU AUG 21 2014 Minor adjustment to account for light showers over Southern Illinois and departing convection over Southwest Indiana before daybreak. The 13km RUC and 3km HRRR suggest a subtle channeled vortiicity intersecting very minor, low amplitude shortwave centered around the 14-17kft layer on the KVWX VAD wind profile between 9-10z. Precipitation chances will remain marginal and suspect subsidence in this layer will serve to speed up clearing of cloud debris by mid-morning. With this in mind, went slightly higher with temperatures through early afternoon. Should clouds linger 1-3 hours longer than expected, may have to dial back temperatures and heat indexes to the main forecast package levels for this afternoon. && .SHORT TERM...(Today through Saturday) Issued at 306 AM CDT THU AUG 21 2014 Strong thunderstorm clusters rolled through northern parts of the CWA early this morning, producing some very heavy rain and gusty winds. They were associated a small upper level disturbance that is moving across parts of southern IL/southwest IN. The only short term model that seems to have a good handle on this complex is the HRRR, which continues to take these remnants east/southeast and out of the EVV Tri State region over the next few hours. There are a few light showers forming further west in southeast MO which may be forming due to decent instability and maybe a weak boundary over that area per the latest LAPS data. Will opt for some isolated coverage through about 13Z to cover any remaining activity as this disturbance moves out of the region. We will see upper heights build today and we should see the mid level clouds clear during the morning hours, leaving the afternoon to heat up. Unlike yesterday, when clouds hung out long enough to mess with temperatures in our northern areas, it appears we should have enough sunshine today that all locations should reach the low/mid 90s, as 850mb temperatures do not really change too much. The only issue may be our eastern counties. If clouds to not clear until late there, the heat advisory may be in jeopardy. Will keep it going area wide for now due to uncertainties in cloud cover. The ring of fire pattern will be rather active to our north, as disturbance rotate around the upper high. Believe that most of the activity should stay well to our north today, tonight and into Friday, but the far northern/northeastern counties might need to be watched just in case outflow boundaries from storms to the north light up further south than anticipated. Friday into Saturday, the upper high over the region becomes even more amplified, as a upper level trough crashes into the Pacific northwest. The atmosphere really dries out in the low levels and even aloft as this occurs. This should really shut off any chances for potential convection. The heat begins to build even more for Friday and Saturday as low level temps rise a few more degrees, which should put us into the mid or upper 90s through Saturday. Night time lows will remain in the mid 70s. This heat, coupled with high humidity values, should continue to warrant our ongoing heat advisory, which might even have to be extended. .LONG TERM...(Saturday night through Wednesday) Issued at 306 AM CDT THU AUG 21 2014 The main concern during the long term period will be the extended duration of potentially hazardous heat. A deep layer subtropical high will be anchored over the Lower Ohio and Mid Mississippi Valleys late in the weekend into early next week. As far as the daily details... Sunday into Monday...the center of the high /850 to 500 mb/ is forecast to be nearly overhead. The models forecast some strengthening of the high...with 500 mb heights near 594 dm by Monday. Heat indices will likely continue to meet or exceed advisory thresholds...requiring an eventual extension of headlines. Tuesday into Wednesday...very little change is indicated regarding the location of the upper ridge. However...the low level anticyclone is forecast to shift eastward. Due to weaker capping and less subsidence...there should be a little more cloudiness and isolated diurnal convection. This moisture may hold daytime highs down a bit. && .AVIATION... Issued at 638 AM CDT THU AUG 21 2014 With this issuance attempted to account for lift associated with minor shortwave moving through the TAF sites before 17z. Added a brief MVFR ceiling for KEVV and KOWB through 17z, otherwise kept ceilings near 110 kft AGL as the dominate cloud cover prior to 17. The ridge should build in quickly this afternoon, diminishing opaque cloud cover below 12kft agl. There may be some cirrus in the area, but did not account for it at this time. Minor visbility restriction was added after 06z Friday for all of the TAF sites, ranging between 5 and 6 statute miles. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...HEAT ADVISORY until 7 PM CDT Saturday FOR ILZ075>078-080>094. MO...HEAT ADVISORY until 7 PM CDT Saturday FOR MOZ076-086-087-100- 107>112-114. IN...HEAT ADVISORY until 7 PM CDT Saturday FOR INZ081-082-085>088. KY...HEAT ADVISORY until 7 PM CDT Saturday FOR KYZ001>022. && $$ UPDATE...Smith AVIATION...Smith
AREA FORECAST DISCUSSION
NWS PADUCAH KY
518 AM CDT Thu Aug 21 2014 .UPDATE... Issued at 517 AM CDT THU AUG 21 2014 Minor adjustment to account for light showers over Southern Illinois and departing convection over Southwest Indiana before daybreak. The 13km RUC and 3km HRRR suggest a subtle channeled vortiicity intersecting very minor, low amplitude shortwave centered around the 14-17kft layer on the KVWX VAD wind profile between 9-10z. Precipitation chances will remain marginal and suspect subsidence in this layer will serve to speed up clearing of cloud debris by mid-morning. With this in mind, went slightly higher with temperatures through early afternoon. Should clouds linger 1-3 hours longer than expected, may have to dial back temperatures and heat indexes to the main forecast package levels for this afternoon. && .SHORT TERM...(Today through Saturday) Issued at 306 AM CDT THU AUG 21 2014 Strong thunderstorm clusters rolled through northern parts of the CWA early this morning, producing some very heavy rain and gusty winds. They were associated a small upper level disturbance that is moving across parts of southern IL/southwest IN. The only short term model that seems to have a good handle on this complex is the HRRR, which continues to take these remnants east/southeast and out of the EVV Tri State region over the next few hours. There are a few light showers forming further west in southeast MO which may be forming due to decent instability and maybe a weak boundary over that area per the latest LAPS data. Will opt for some isolated coverage through about 13Z to cover any remaining activity as this disturbance moves out of the region. We will see upper heights build today and we should see the mid level clouds clear during the morning hours, leaving the afternoon to heat up. Unlike yesterday, when clouds hung out long enough to mess with temperatures in our northern areas, it appears we should have enough sunshine today that all locations should reach the low/mid 90s, as 850mb temperatures do not really change too much. The only issue may be our eastern counties. If clouds to not clear until late there, the heat advisory may be in jeopardy. Will keep it going area wide for now due to uncertainties in cloud cover. The ring of fire pattern will be rather active to our north, as disturbance rotate around the upper high. Believe that most of the activity should stay well to our north today, tonight and into Friday, but the far northern/northeastern counties might need to be watched just in case outflow boundaries from storms to the north light up further south than anticipated. Friday into Saturday, the upper high over the region becomes even more amplified, as a upper level trough crashes into the Pacific northwest. The atmosphere really dries out in the low levels and even aloft as this occurs. This should really shut off any chances for potential convection. The heat begins to build even more for Friday and Saturday as low level temps rise a few more degrees, which should put us into the mid or upper 90s through Saturday. Night time lows will remain in the mid 70s. This heat, coupled with high humidity values, should continue to warrant our ongoing heat advisory, which might even have to be extended. .LONG TERM...(Saturday night through Wednesday) Issued at 306 AM CDT THU AUG 21 2014 The main concern during the long term period will be the extended duration of potentially hazardous heat. A deep layer subtropical high will be anchored over the Lower Ohio and Mid Mississippi Valleys late in the weekend into early next week. As far as the daily details... Sunday into Monday...the center of the high /850 to 500 mb/ is forecast to be nearly overhead. The models forecast some strengthening of the high...with 500 mb heights near 594 dm by Monday. Heat indices will likely continue to meet or exceed advisory thresholds...requiring an eventual extension of headlines. Tuesday into Wednesday...very little change is indicated regarding the location of the upper ridge. However...the low level anticyclone is forecast to shift eastward. Due to weaker capping and less subsidence...there should be a little more cloudiness and isolated diurnal convection. This moisture may hold daytime highs down a bit. && .AVIATION... Issued at 306 AM CDT THU AUG 21 2014 Other than some lingering rain/thunder storms over the KEVV which will exit the area within the next hour, all is quiet over the other terminals. Some morning fog may develop though early this morning, although extensive cloud cover may preclude vsbys from going down too far. Mid level clouds should slowly move out of the area this morning and some cu may form by afternoon. Light southwest winds are expected. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...HEAT ADVISORY until 7 PM CDT Saturday FOR ILZ075>078-080>094. MO...HEAT ADVISORY until 7 PM CDT Saturday FOR MOZ076-086-087-100- 107>112-114. IN...HEAT ADVISORY until 7 PM CDT Saturday FOR INZ081-082-085>088. KY...HEAT ADVISORY until 7 PM CDT Saturday FOR KYZ001>022. && $$ UPDATE...Smith
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1257 PM CDT THU AUG 21 2014 .AVIATION... FOR THE 21/18Z TAFS...DENSE CU FIELD WITH CIGS GENERALLY BETWEEN 2500 AND 3000 FEET PERSISTS RESULTING IN A MIX OF MVFR/LOW-END VFR FLIGHT CONDITIONS. CIGS SHOULD CONTINUE TO SLOWLY LIFT WHILE OVERALL CLOUD COVER GRADUALLY THINS. SEA BREEZE CONVECTION IS ALREADY DEVELOPING AND WILL LIKELY EXPAND IN COVERAGE SLIGHTLY BUT SHOULD REMAIN SOUTH OF A LINE FROM KLFK TO KMLU. SHWRS/TSTMS SHOULD DISSIPATE AROUND SUNSET. ANOTHER ROUND OF MVFR/IFR CIGS/VSBYS ARE EXPECTED DURING THE OVERNIGHT/EARLY MORNING HRS FRIDAY WITH SLOW IMPROVEMENT LATE IN THE TAF PERIOD. /09/ && .PREV DISCUSSION... /ISSUED 1035 AM CDT THU AUG 21 2014/ DISCUSSION... LATEST VIS SATELLITE IMAGERY SHOWING EXPANSIVE STRATOCUMULUS DECK ENCOMPASSING MOST OF THE FOUR STATE REGION THIS MORNING. CUMULUS IS TAKING ON MORE OF A HORIZONTAL ROW APPEARANCE WHICH IS INDICATIVE OF SOME MIXING BEGINNING TO TAKE PLACE IN THE LOWER ATMOSPHERE AS HEATING TAKES PLACE. AS A RESULT...EXPECT SOME PEEKS OF SUN TO BEGIN OVER THE NEXT COUPLE HOURS WITH EVENTUALLY SKIES BECOMING PARTLY CLOUDY ACROSS THE REGION. STRONG WINDS IN THE LOWEST 5KFT ALLOWED THE STRATUS TO MOVE QUICKLY NORTHWARD AND CONDENSE EARLY THIS MORNING AND WE ARE STARTING TO SEE SOME OF THIS MIX DOWN ACROSS NE TX THIS MORNING WITH STRONGER WIND GUSTS NOTED NORTH AND WEST OF THE I-30 CORRIDOR ACROSS TX. LOOKING AT NEW RAW 12Z NAM OUTPUT...THERE REMAINS A WEAK SHEAR AXIS ACROSS OUR EASTERN MOST ZONES EARLY THIS MORNING. WEAK BUT OBVIOUS 850-700MB THETAE AXIS ALSO RESIDES ACROSS THIS GENERAL AREA AND AS A RESULT...THIS WILL MOST LIKELY BE THE FAVORABLE REGION TO SEE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS LATER TODAY. OTHERWISE...ONCE THE CLOUDS THIN...SHOULD HAVE NO PROBLEMS GETTING TEMPERATURES TO REACH FCST MAX TEMPS WITH 15Z OBSERVATIONS ALREADY RUNNING SOME 1 TO 3 DEGREES ABOVE THOSE EXPERIENCED ON WEDNESDAY ATTM. NO UPDATE NECESSARY TO THE FORECAST THIS MORNING. 13 PREV DISCUSSION... /ISSUED 435 AM CDT THU AUG 21 2014/ DISCUSSION... 11-3.9U SATELLITE IMAGERY THIS MORNING INDICATES A VORTICITY MAXIMUM OVER NCNTRL LA...WHICH IS ALONG A ELEVATED WEAK SHEAR AXIS NOTED ON THE WATER VAPOR LOOP EXTENDING FROM SE TX ACROSS NCNTRL LA INTO CNTRL MS/NRN AL. THIS FEATURE HAS MAINTAINED AN EXTENSIVE AC CANOPY THIS MORNING OVER MUCH OF NCNTRL LA...WHICH ARE THE CONVECTIVE REMNANTS OF THE ISOLATED SEABREEZE CONVECTION THAT AFFECTED THESE AREAS WEDNESDAY AFTERNOON AND EVENING. A WEAK UPPER LOW NOTED ON THE WATER VAPOR LOOP NOW AFFECTING THE ERN MX COAST S OF BRO HAS ALREADY RESULTED IN ENHANCED ONSHORE FLOW WHICH HAS LED TO INCREASED MOISTURE CONVERGENCE ALONG A W TO E SFC TROUGH WHICH LIES NEAR THE I-10 CORRIDOR. THIS HAS RESULTED IN ISOLATED CONVECTION DEVELOPING/STREAMING N ACROSS SW LA...BUT HAVE WEAKENED WHERE SFC CONVERGENCE IS LOST FARTHER N OF THE SFC TROUGH. THE PROGS DO WEAKEN THE VORT MAX LATER TODAY AS THE CENTER OF THE 500MB RIDGE BEGINS TO BUILD NNW INTO THE LOWER MS VALLEY...BUT SHOULD STILL SEE ANOTHER DAY WHERE SEABREEZE CONVECTION WILL AFFECT THE SRN ZONES MAINLY DURING THE AFTERNOON/EARLY EVENING. GIVEN THE SSW 850-700MB FLOW...THE SEABREEZE SHOULD NOT PUSH AS FAR N ACROSS E TX/NW LA AS IT HAS IN RECENT DAYS...BUT THE HRRR AND GFS SUGGEST THAT THE CONVECTION COULD PUSH FARTHER NNE ACROSS THE ERN SECTIONS OF NCNTRL LA. FOR THAT REASON...HAVE EXTENDED SLIGHT CHANCE POPS FARTHER N INTO LINCOLN/UNION/OUACHITA PARISHES THIS AFTERNOON/EVENING...BUT A STABILIZING BNDRY LYR FROM THE LOSS OF HEATING RESULTS IN THE QUICK DISSIPATION OF THE CONVECTION. DID ALSO INCLUDE LOW CHANCE POPS FOR THE SE SECTIONS OF NCNTRL LA...WHERE EXTRAPOLATION OF THE CURRENT CONVECTION WILL LIKELY RESULT IN ADDITIONAL OUTFLOW BNDRYS THAT WILL FOCUS MORE SCT DEVELOPMENT ESPECIALLY WHEN PEAK HEATING IS REACHED. WITH THE AC SHIELD GRADUALLY THINNING BY AFTERNOON...AND THE MORNING LOW STRATUS QUICKLY LIFTING THIS MORNING...MAX TEMPS TODAY SHOULD BE NEAR IF NOT SLIGHTLY WARMER THAN WHAT WAS OBSERVED WEDNESDAY. THE HEAT IS ON FRIDAY THROUGH EARLY NEXT WEEK AS THE CENTER OF THE UPPER RIDGE RESIDES IN VC OF OUR REGION OVER LOWER MS VALLEY. THIS SHOULD RESULT IN MAX TEMPS CLIMBING INTO THE UPPER 90S AREAWIDE BY THE WEEKEND...WITH A FEW TRIPLE DIGIT TEMPS NOT OUT OF THE QUESTION OVER PORTIONS OF THE REGION. EVEN WITH THE 700MB RIDGE CENTERED OVER ERN AR SUNDAY...AMPLE SOIL MOISTURE OVER ERN LA/SE AR SHOULD HELP MAINTAIN TEMPS BELOW THE CENTURY MARK...BUT RESULT IN HIGHER DEWPOINTS/HEAT INDICES SUCH THAT A HEAT ADVISORY MAY BE NEEDED FOR PORTIONS OF NCNTRL LA/S AR THIS WEEKEND. HAVE TRENDED SLIGHTLY COOLER THAN MAVMOS THIS WEEKEND...ESPECIALLY GIVEN ITS WARM BIAS FOR THE LAST SEVERAL WEEKS. THE PROGS CONTINUE TO SHIFT THE UPPER RIDGE CENTER FARTHER NE INTO THE MID MS VALLEY BY MONDAY WITH THE RIDGE AMPLIFYING INTO THE GREAT LAKES REGION...WITH THE EXTREME HEAT BEGINNING TO WEAKEN ITS GRIP ON OUR AREA. BUT THIS WILL BE GRADUAL...UNTIL WEAKNESSES BENEATH THE RIDGE CENTER ARE ABLE TO MIGRATE W ACROSS MS/SE LA MONDAY...WHICH MAY TOUCH OFF ISOLATED CONVECTION OVER MUCH OF NCNTRL LA/DEEP E TX. WITH THESE WEAKNESSES NUDGING CLOSER TO OUR REGION BY TUESDAY...MORE IN THE WAY OF SCT CONVECTION IS EXPECTED OVER NCNTRL LA/DEEP E TX...WITH ISOLATED CONVECTION POSSIBLE FARTHER W. FORECAST CONFIDENCE DIMINISHES THEREAFTER...WITH THE GFS SUGGESTING AN UPPER TROUGH QUICKLY SHIFTING E ACROSS THE PLAINS WEDNESDAY AND ACROSS THE SRN PLAINS/LOWER MS VALLEY THURSDAY. MEANWHILE...THE ECMWF REMAINS STOUT WITH THE RIDGE CENTER ACTUALLY RETROGRADING W BACK ACROSS THE CNTRL CONUS...WITH A MUCH SLOWER AND WEAKER TROUGH PASSAGE /IF ANY AT ALL/ BY NEXT WEEKEND. FOR NOW...HAVE MAINTAINED SLIGHT CHANCE POPS THROUGHOUT THE REMAINDER OF THE EXTENDED...WHILE KEEPING NEAR NORMAL TEMPS THROUGH THE PERIOD. PRELIMS TO FOLLOW BELOW... 15 && .PRELIMINARY POINT TEMPS/POPS... SHV 96 74 97 74 98 / 10 10 0 0 0 MLU 94 73 96 73 97 / 20 20 0 0 0 DEQ 94 72 95 72 96 / 0 0 0 0 0 TXK 95 74 96 74 97 / 0 0 0 0 0 ELD 94 72 96 73 97 / 10 10 0 0 0 TYR 97 75 97 75 97 / 10 10 0 0 0 GGG 95 74 96 74 97 / 10 10 0 0 0 LFK 96 74 97 74 97 / 20 10 0 0 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...NONE. LA...NONE. OK...NONE. TX...NONE. && $$ 09
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
1035 AM CDT THU AUG 21 2014 .DISCUSSION... LATEST VIS SATELLITE IMAGERY SHOWING EXPANSIVE STRATOCUMULUS DECK ENCOMPASSING MOST OF THE FOUR STATE REGION THIS MORNING. CUMULUS IS TAKING ON MORE OF A HORIZONTAL ROW APPEARANCE WHICH IS INDICATIVE OF SOME MIXING BEGINNING TO TAKE PLACE IN THE LOWER ATMOSPHERE AS HEATING TAKES PLACE. AS A RESULT...EXPECT SOME PEEKS OF SUN TO BEGIN OVER THE NEXT COUPLE HOURS WITH EVENTUALLY SKIES BECOMING PARTLY CLOUDY ACROSS THE REGION. STRONG WINDS IN THE LOWEST 5KFT ALLOWED THE STRATUS TO MOVE QUICKLY NORTHWARD AND CONDENSE EARLY THIS MORNING AND WE ARE STARTING TO SEE SOME OF THIS MIX DOWN ACROSS NE TX THIS MORNING WITH STRONGER WIND GUSTS NOTED NORTH AND WEST OF THE I-30 CORRIDOR ACROSS TX. LOOKING AT NEW RAW 12Z NAM OUTPUT...THERE REMAINS A WEAK SHEAR AXIS ACROSS OUR EASTERN MOST ZONES EARLY THIS MORNING. WEAK BUT OBVIOUS 850-700MB THETAE AXIS ALSO RESIDES ACROSS THIS GENERAL AREA AND AS A RESULT...THIS WILL MOST LIKELY BE THE FAVORABLE REGION TO SEE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS LATER TODAY. OTHERWISE...ONCE THE CLOUDS THIN...SHOULD HAVE NO PROBLEMS GETTING TEMPERATURES TO REACH FCST MAX TEMPS WITH 15Z OBSERVATIONS ALREADY RUNNING SOME 1 TO 3 DEGREES ABOVE THOSE EXPERIENCED ON WEDNESDAY ATTM. NO UPDATE NECESSARY TO THE FORECAST THIS MORNING. 13 && .PREV DISCUSSION... /ISSUED 435 AM CDT THU AUG 21 2014/ DISCUSSION... 11-3.9U SATELLITE IMAGERY THIS MORNING INDICATES A VORTICITY MAXIMUM OVER NCNTRL LA...WHICH IS ALONG A ELEVATED WEAK SHEAR AXIS NOTED ON THE WATER VAPOR LOOP EXTENDING FROM SE TX ACROSS NCNTRL LA INTO CNTRL MS/NRN AL. THIS FEATURE HAS MAINTAINED AN EXTENSIVE AC CANOPY THIS MORNING OVER MUCH OF NCNTRL LA...WHICH ARE THE CONVECTIVE REMNANTS OF THE ISOLATED SEABREEZE CONVECTION THAT AFFECTED THESE AREAS WEDNESDAY AFTERNOON AND EVENING. A WEAK UPPER LOW NOTED ON THE WATER VAPOR LOOP NOW AFFECTING THE ERN MX COAST S OF BRO HAS ALREADY RESULTED IN ENHANCED ONSHORE FLOW WHICH HAS LED TO INCREASED MOISTURE CONVERGENCE ALONG A W TO E SFC TROUGH WHICH LIES NEAR THE I-10 CORRIDOR. THIS HAS RESULTED IN ISOLATED CONVECTION DEVELOPING/STREAMING N ACROSS SW LA...BUT HAVE WEAKENED WHERE SFC CONVERGENCE IS LOST FARTHER N OF THE SFC TROUGH. THE PROGS DO WEAKEN THE VORT MAX LATER TODAY AS THE CENTER OF THE 500MB RIDGE BEGINS TO BUILD NNW INTO THE LOWER MS VALLEY...BUT SHOULD STILL SEE ANOTHER DAY WHERE SEABREEZE CONVECTION WILL AFFECT THE SRN ZONES MAINLY DURING THE AFTERNOON/EARLY EVENING. GIVEN THE SSW 850-700MB FLOW...THE SEABREEZE SHOULD NOT PUSH AS FAR N ACROSS E TX/NW LA AS IT HAS IN RECENT DAYS...BUT THE HRRR AND GFS SUGGEST THAT THE CONVECTION COULD PUSH FARTHER NNE ACROSS THE ERN SECTIONS OF NCNTRL LA. FOR THAT REASON...HAVE EXTENDED SLIGHT CHANCE POPS FARTHER N INTO LINCOLN/UNION/OUACHITA PARISHES THIS AFTERNOON/EVENING...BUT A STABILIZING BNDRY LYR FROM THE LOSS OF HEATING RESULTS IN THE QUICK DISSIPATION OF THE CONVECTION. DID ALSO INCLUDE LOW CHANCE POPS FOR THE SE SECTIONS OF NCNTRL LA...WHERE EXTRAPOLATION OF THE CURRENT CONVECTION WILL LIKELY RESULT IN ADDITIONAL OUTFLOW BNDRYS THAT WILL FOCUS MORE SCT DEVELOPMENT ESPECIALLY WHEN PEAK HEATING IS REACHED. WITH THE AC SHIELD GRADUALLY THINNING BY AFTERNOON...AND THE MORNING LOW STRATUS QUICKLY LIFTING THIS MORNING...MAX TEMPS TODAY SHOULD BE NEAR IF NOT SLIGHTLY WARMER THAN WHAT WAS OBSERVED WEDNESDAY. THE HEAT IS ON FRIDAY THROUGH EARLY NEXT WEEK AS THE CENTER OF THE UPPER RIDGE RESIDES IN VC OF OUR REGION OVER LOWER MS VALLEY. THIS SHOULD RESULT IN MAX TEMPS CLIMBING INTO THE UPPER 90S AREAWIDE BY THE WEEKEND...WITH A FEW TRIPLE DIGIT TEMPS NOT OUT OF THE QUESTION OVER PORTIONS OF THE REGION. EVEN WITH THE 700MB RIDGE CENTERED OVER ERN AR SUNDAY...AMPLE SOIL MOISTURE OVER ERN LA/SE AR SHOULD HELP MAINTAIN TEMPS BELOW THE CENTURY MARK...BUT RESULT IN HIGHER DEWPOINTS/HEAT INDICES SUCH THAT A HEAT ADVISORY MAY BE NEEDED FOR PORTIONS OF NCNTRL LA/S AR THIS WEEKEND. HAVE TRENDED SLIGHTLY COOLER THAN MAVMOS THIS WEEKEND...ESPECIALLY GIVEN ITS WARM BIAS FOR THE LAST SEVERAL WEEKS. THE PROGS CONTINUE TO SHIFT THE UPPER RIDGE CENTER FARTHER NE INTO THE MID MS VALLEY BY MONDAY WITH THE RIDGE AMPLIFYING INTO THE GREAT LAKES REGION...WITH THE EXTREME HEAT BEGINNING TO WEAKEN ITS GRIP ON OUR AREA. BUT THIS WILL BE GRADUAL...UNTIL WEAKNESSES BENEATH THE RIDGE CENTER ARE ABLE TO MIGRATE W ACROSS MS/SE LA MONDAY...WHICH MAY TOUCH OFF ISOLATED CONVECTION OVER MUCH OF NCNTRL LA/DEEP E TX. WITH THESE WEAKNESSES NUDGING CLOSER TO OUR REGION BY TUESDAY...MORE IN THE WAY OF SCT CONVECTION IS EXPECTED OVER NCNTRL LA/DEEP E TX...WITH ISOLATED CONVECTION POSSIBLE FARTHER W. FORECAST CONFIDENCE DIMINISHES THEREAFTER...WITH THE GFS SUGGESTING AN UPPER TROUGH QUICKLY SHIFTING E ACROSS THE PLAINS WEDNESDAY AND ACROSS THE SRN PLAINS/LOWER MS VALLEY THURSDAY. MEANWHILE...THE ECMWF REMAINS STOUT WITH THE RIDGE CENTER ACTUALLY RETROGRADING W BACK ACROSS THE CNTRL CONUS...WITH A MUCH SLOWER AND WEAKER TROUGH PASSAGE /IF ANY AT ALL/ BY NEXT WEEKEND. FOR NOW...HAVE MAINTAINED SLIGHT CHANCE POPS THROUGHOUT THE REMAINDER OF THE EXTENDED...WHILE KEEPING NEAR NORMAL TEMPS THROUGH THE PERIOD. PRELIMS TO FOLLOW BELOW... 15 && .PRELIMINARY POINT TEMPS/POPS... SHV 96 74 97 74 98 / 10 10 0 0 0 MLU 94 73 96 73 97 / 20 20 0 0 0 DEQ 94 72 95 72 96 / 0 0 0 0 0 TXK 95 74 96 74 97 / 0 0 0 0 0 ELD 94 72 96 73 97 / 10 10 0 0 0 TYR 97 75 97 75 97 / 10 10 0 0 0 GGG 95 74 96 74 97 / 10 10 0 0 0 LFK 96 74 97 74 97 / 20 10 0 0 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...NONE. LA...NONE. OK...NONE. TX...NONE. && $$ 13
AREA FORECAST DISCUSSION
NWS SHREVEPORT LA
435 AM CDT THU AUG 21 2014 .DISCUSSION... 11-3.9U SATELLITE IMAGERY THIS MORNING INDICATES A VORTICITY MAXIMUM OVER NCNTRL LA...WHICH IS ALONG A ELEVATED WEAK SHEAR AXIS NOTED ON THE WATER VAPOR LOOP EXTENDING FROM SE TX ACROSS NCNTRL LA INTO CNTRL MS/NRN AL. THIS FEATURE HAS MAINTAINED AN EXTENSIVE AC CANOPY THIS MORNING OVER MUCH OF NCNTRL LA...WHICH ARE THE CONVECTIVE REMNANTS OF THE ISOLATED SEABREEZE CONVECTION THAT AFFECTED THESE AREAS WEDNESDAY AFTERNOON AND EVENING. A WEAK UPPER LOW NOTED ON THE WATER VAPOR LOOP NOW AFFECTING THE ERN MX COAST S OF BRO HAS ALREADY RESULTED IN ENHANCED ONSHORE FLOW WHICH HAS LED TO INCREASED MOISTURE CONVERGENCE ALONG A W TO E SFC TROUGH WHICH LIES NEAR THE I-10 CORRIDOR. THIS HAS RESULTED IN ISOLATED CONVECTION DEVELOPING/STREAMING N ACROSS SW LA...BUT HAVE WEAKENED WHERE SFC CONVERGENCE IS LOST FARTHER N OF THE SFC TROUGH. THE PROGS DO WEAKEN THE VORT MAX LATER TODAY AS THE CENTER OF THE 500MB RIDGE BEGINS TO BUILD NNW INTO THE LOWER MS VALLEY...BUT SHOULD STILL SEE ANOTHER DAY WHERE SEABREEZE CONVECTION WILL AFFECT THE SRN ZONES MAINLY DURING THE AFTERNOON/EARLY EVENING. GIVEN THE SSW 850-700MB FLOW...THE SEABREEZE SHOULD NOT PUSH AS FAR N ACROSS E TX/NW LA AS IT HAS IN RECENT DAYS...BUT THE HRRR AND GFS SUGGEST THAT THE CONVECTION COULD PUSH FARTHER NNE ACROSS THE ERN SECTIONS OF NCNTRL LA. FOR THAT REASON...HAVE EXTENDED SLIGHT CHANCE POPS FARTHER N INTO LINCOLN/UNION/OUACHITA PARISHES THIS AFTERNOON/EVENING...BUT A STABILIZING BNDRY LYR FROM THE LOSS OF HEATING RESULTS IN THE QUICK DISSIPATION OF THE CONVECTION. DID ALSO INCLUDE LOW CHANCE POPS FOR THE SE SECTIONS OF NCNTRL LA...WHERE EXTRAPOLATION OF THE CURRENT CONVECTION WILL LIKELY RESULT IN ADDITIONAL OUTFLOW BNDRYS THAT WILL FOCUS MORE SCT DEVELOPMENT ESPECIALLY WHEN PEAK HEATING IS REACHED. WITH THE AC SHIELD GRADUALLY THINNING BY AFTERNOON...AND THE MORNING LOW STRATUS QUICKLY LIFTING THIS MORNING...MAX TEMPS TODAY SHOULD BE NEAR IF NOT SLIGHTLY WARMER THAN WHAT WAS OBSERVED WEDNESDAY. THE HEAT IS ON FRIDAY THROUGH EARLY NEXT WEEK AS THE CENTER OF THE UPPER RIDGE RESIDES IN VC OF OUR REGION OVER LOWER MS VALLEY. THIS SHOULD RESULT IN MAX TEMPS CLIMBING INTO THE UPPER 90S AREAWIDE BY THE WEEKEND...WITH A FEW TRIPLE DIGIT TEMPS NOT OUT OF THE QUESTION OVER PORTIONS OF THE REGION. EVEN WITH THE 700MB RIDGE CENTERED OVER ERN AR SUNDAY...AMPLE SOIL MOISTURE OVER ERN LA/SE AR SHOULD HELP MAINTAIN TEMPS BELOW THE CENTURY MARK...BUT RESULT IN HIGHER DEWPOINTS/HEAT INDICES SUCH THAT A HEAT ADVISORY MAY BE NEEDED FOR PORTIONS OF NCNTRL LA/S AR THIS WEEKEND. HAVE TRENDED SLIGHTLY COOLER THAN MAVMOS THIS WEEKEND...ESPECIALLY GIVEN ITS WARM BIAS FOR THE LAST SEVERAL WEEKS. THE PROGS CONTINUE TO SHIFT THE UPPER RIDGE CENTER FARTHER NE INTO THE MID MS VALLEY BY MONDAY WITH THE RIDGE AMPLIFYING INTO THE GREAT LAKES REGION...WITH THE EXTREME HEAT BEGINNING TO WEAKEN ITS GRIP ON OUR AREA. BUT THIS WILL BE GRADUAL...UNTIL WEAKNESSES BENEATH THE RIDGE CENTER ARE ABLE TO MIGRATE W ACROSS MS/SE LA MONDAY...WHICH MAY TOUCH OFF ISOLATED CONVECTION OVER MUCH OF NCNTRL LA/DEEP E TX. WITH THESE WEAKNESSES NUDGING CLOSER TO OUR REGION BY TUESDAY...MORE IN THE WAY OF SCT CONVECTION IS EXPECTED OVER NCNTRL LA/DEEP E TX...WITH ISOLATED CONVECTION POSSIBLE FARTHER W. FORECAST CONFIDENCE DIMINISHES THEREAFTER...WITH THE GFS SUGGESTING AN UPPER TROUGH QUICKLY SHIFTING E ACROSS THE PLAINS WEDNESDAY AND ACROSS THE SRN PLAINS/LOWER MS VALLEY THURSDAY. MEANWHILE...THE ECMWF REMAINS STOUT WITH THE RIDGE CENTER ACTUALLY RETROGRADING W BACK ACROSS THE CNTRL CONUS...WITH A MUCH SLOWER AND WEAKER TROUGH PASSAGE /IF ANY AT ALL/ BY NEXT WEEKEND. FOR NOW...HAVE MAINTAINED SLIGHT CHANCE POPS THROUGHOUT THE REMAINDER OF THE EXTENDED...WHILE KEEPING NEAR NORMAL TEMPS THROUGH THE PERIOD. PRELIMS TO FOLLOW BELOW... 15 && .PRELIMINARY POINT TEMPS/POPS... SHV 96 74 97 74 98 / 5 5 0 0 0 MLU 94 73 96 73 97 / 20 20 0 0 0 DEQ 94 72 95 72 96 / 0 0 0 0 0 TXK 95 74 96 74 97 / 0 0 0 0 0 ELD 94 72 96 73 97 / 5 5 0 0 0 TYR 97 75 97 75 97 / 5 5 0 0 0 GGG 95 74 96 74 97 / 5 5 0 0 0 LFK 96 74 97 74 97 / 20 10 0 0 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...NONE. LA...NONE. OK...NONE. TX...NONE. && $$ 15
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
239 PM EDT THU AUG 21 2014 .SYNOPSIS... A STATIONARY FRONT WILL WAVER ACROSS THE MID ATLANTIC AS RIPPLES OF LOW PRESSURE MOVE ALONG THE BOUNDARY. AN WILL TRAVERSE THE FRONT FRIDAY NIGHT...WHICH WILL PUSH IT SOUTH AS A COLD FRONT. HIGH PRESSURE FROM NEW ENGLAND WILL DOWN DOWN THE EAST COAST THIS WEEKEND. && .NEAR TERM /TONIGHT/... ISOLD TSTMS HV ALREADY DVLPD IN THE WRN PART OF THE FCST AREA IN THE SUMMERTIME AIR MASS. MAIN AREA OF PCPN HAS SPENT THE DAY TRAVERSING ACROSS IN INTO SRN OH ALONG A WARM FNT. THIS WL LKLY MOVE INTO THE WRN SXN OF THE CWA IN THE 4-5 PM TIMEFRAME...MOVG E OF THE MTNS THIS EVE. QUSTN WL BE IF IT CAN HOLD TOGETHER - IT ISN`T TOO IMPRESSIVE ATTM AND HRRR IS EVEN LESS SO AS IT TRIES TO MOVE TOWARDS THE METROS AFTR 00Z. REGARDING SVR THREAT - PULSE SVR WOULD BE WORST CASE SCENARIO. FOG LOOKS TO BE OF LESSER CONCERN TNGT THAN LAST NGT. LOWS IN THE 60S W OF I-95...L70S E. && .SHORT TERM /FRIDAY/... BNDRY RMNG IN THE AREA FRIDAY WL MOST LKLY SERVE AS A FOCUS FOR TSTMS. WL KEEP POPS IN CHC RANGE. AGN SVR THREAT LOOKS LOW - LO LVL WIND FIELD IS WEAK...CAPE IS NOT OVERLY IMPRESSIVE. FFG IS RLTVLY HIGH. HIGHS IN THE MU80S. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... AN UPPER LEVEL VORTICITY MAX WILL DIP THROUGH THE AREA OVERNIGHT FRIDAY...BRINGING ANOTHER BOUT OF ENHANCED RAINFALL. SURFACE HIGH PRESSURE CENTERED OVER NEW ENGLAND WILL RIDGE DOWN THE EAST COAST AS AN UPPER LEVEL SUBTROPICAL RIDGE BUILDS OVER THE EASTERN US. THE SURFACE RIDGE BUILDING DOWN INTO THE AREA WILL WORK WITH LOW PRESSURE OFF OF THE CAROLINA COAST TO BRING ONSHORE FLOW INTO THE MID-ATLANTIC BEGINNING SATURDAY MORNING. THE PRIMARY EFFECTS OF THE INCOMING MARINE AIRMASS WILL BE SEASONABLY COOL TEMPERATURES AND MOSTLY CLOUDY TO OVERCAST SKIES. EXPECT HIGHS ON SATURDAY...SUNDAY AND MONDAY TO ONLY BE IN THE MID TO UPPER 70S. HIGH PRESSURE WILL MOVE MORE OVERHEAD BY MONDAY NIGHT AND ONSHORE FLOW WILL MOSTLY BE SHUT OFF. LIGHT SOUTHERLY FLOW WILL BEGIN TO FILL INTO THE AREA TUESDAY...LEADING TO AN TREND TOWARD MORE SEASONABLE TEMPERATURES BY THE MIDDLE OF THE WEEK WITH HIGHS NEAR 80 ON TUESDAY AND IN THE MID 80S WEDNESDAY AND THURSDAY. HOWEVER...WITH A RATHER DRY PROFILE CONVECTION IS UNLIKELY TUESDAY OR WEDNESDAY. THE NEXT THREAT FOR STORMS ACROSS THE AREA SHOULD BE THURSDAY AS A COLD FRONT APPROACHES THE AREA. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... VFR CONDS XPCTD OUTSIDE OF ANY TSTMS. FOG MAY DVLP AT IAD/CHO/MRB AFTR MDNGT...BUT NOT XPCTD TO BE AS DENSE AS IT WAS THIS MRNG. TSTMS AGN PSBL FRI AFTN. PERIODS OF LOW CEILINGS ARE POSSIBLE AS AN UPPER LEVEL VORT MAX CROSSES THE AREA FRIDAY NIGHT AND THEN AGAIN OVER THE WEEKEND AND INTO EARLY NEXT WEEK AS A MARINE AIRMASS SETTLES INTO THE AREA. && .MARINE... WINDS XPCTD TO RMN BLO SCA VALUES TNGT/FRI. RW/TRW MAY OCCUR ON THE WATERS THIS EVE AND AGN FRI AFTN. A SMALL CRAFT ADVISORY MAY BE NECESSARY FOR THE WIDEST ZONES OF THE LOWER MARYLAND CHESAPEAKE BAY AND THE LOWER TIDAL POTOMAC SATURDAY AFTERNOON THROUGH SUNDAY NIGHT IN BREEZY EASTERLY FLOW. && .TIDES/COASTAL FLOODING... WATER LVLS ABOUT 3/4 FT ABV ASTRO NORMS. FRI MRNG TIDE WL BE HIGH...BUT AM NOT ANTICIPATING REACHING CRITERIA ATTM. HOWEVER... WE ARE WORKING ON A MARGIN OF INCHES. LATER SHIFTS WL MONITOR THE SITUATION. THERE COULD BE MORE NUISANCE ISSUES THIS WKND. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ PRODUCTS...WOODY!/CEB
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
227 PM EDT THU AUG 21 2014 .SYNOPSIS... UNSETTLED WEATHER WILL CONTINUE THROUGH THE WEEKEND WITH OCCASIONAL SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH TONIGHT/... SHOWERS AND THUNDERSTORMS SUPPORTED BY UPPER LEVEL WAVE IS NOW MOVING ACROSS THE UPPER OHIO VALLEY. ADDED LIKELY POPS TO THE NORTH AS UPPER WAVE PASSES THROUGH IN THE AFTERNOON WITH COVERAGE OF CONVECTION EXPECTED TO INCREASE. VISIBLE SATELLITE IMAGERY SHOWS AMPLE CLOUD COVERAGE ACROSS PITTSBURGH AND SOUTH. HENCE...OPTIMAL DAYTIME HEATING WILL NOT OCCUR IN THAT REGION...HOWEVER...INCREASING MOISTURE WILL AID IN INSTABILITY YIELDING SHOWERS AND THUNDERSTORMS. TO THE NORTH...SUFFICIENT HEATING DUE TO LESS CLOUDS HAVE RAMPED UP INSTABILITY. RAP ANALYSIS SHOWS RELATIVELY STRONGER SHEAR IN THIS ZONE AS WELL. THEREFORE...ISOLATED STRONG TO MARGINALLY SEVERE STORMS ARE POSSIBLE THIS AFTERNOON NORTH OF PITTSBURGH. GREATER COVERAGE OF CONVECTION IS EXPECTED TO WANE LATER IN THE EVENING DUE TO LOSS OF HEATING. SOME SHOWERS MAY STILL LINGER ACROSS THE AREA OVERNIGHT DUE TO THE NEARLY STATIONARY SURFACE BOUNDARY. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... AS THE NEXT SHORTWAVE CROSSES THE REGION FROM A WEAKENING AND EXITING UPPER LOW...AXIS OF HEAVY RAINFALL WILL SHIFT EAST ON FRIDAY AS THE BOUNDARY BEGINS TO SLOWLY MOVE. UNCERTAINTY STILL EXISTS FOR ANY FLOODING AS MODELS ARE IN MINOR DISAGREEMENT FOR THE PLACEMENT OF HEAVY RAIN. USED MODEL BLEND OF GFS/NAM FOR POPS AND HPC FOR QPF. UPPER LEVEL RIDGE DEVELOPS THROUGH THE WEEKEND BRINGING SLIGHTLY WARMER THAN NORMAL TEMPERATURES. A FEW SHORTWAVES TOPPING THE RIDGE BRINGS THE CHANCE OF SHOWERS AND THUNDERSTORMS...AT LEAST FOR SATURDAY BUT OVERALL COVERAGE SHOULD BE SMALL. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MORE CLARITY EXISTS IN THE EXTENDED FORECAST WITH THE LATEST ROUND OF MODEL GUIDANCE. UPPER RIDGE BUILDING NORTH WILL WORK TO DEFLECT AN ADVANCING LOW PRESSURE SYSTEM WELL NORTH OF THE GREAT LAKES EARLY NEXT WEEK...RESULTING IN A WARMING AND DRYING TREND. TEMPERATURES SHOULD REMAIN AT OR EVEN JUST ABOVE AVERAGE INTO THE MIDDLE OF NEXT WEEK. LOOKING A LITTLE FARTHER OUT IN TIME THAN USUAL...NO EFFECTS ARE EXPECTED LOCALLY FROM ANYTHING THAT MAY DEVELOP IN THE TROPICS. TAX/TG && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... ALTHOUGH STRATIFORM RAIN THIS AFTERNOON/EVENING IS EXPECTED TO PRIMARILY AFFECT ZZV...HLG...AND MGW...SCATTERED PRECIPITATION IS EXPECTED AT THE REST OF TAF SITES. A SECONDARY AXIS OF PRECIPITATION SEEMS TO BE DEVELOPING ALONG THE INTERSTATE 80 CORRIDOR...AND PRECIPITATION HAS BEEN ADDED TO FKL/DUJ TAFS AS WELL. IFR CONDITIONS WILL BE POSSIBLE IN ANY THUNDERSTORM...BUT DID NOT WANT TO BLANKET ALL SITES WITH THAT IN PREVAILING CONDITIONS. SHOWERS SHOULD DIMINISH IN COVERAGE OVERNIGHT...ALTHOUGH MODELS ARE SUGGESTING ANOTHER ROUND OF RAIN AFTER MIDNIGHT. HAVE CONTINUED WITH PREVAILING PRECIPITATION LATE TONIGHT INTO FRIDAY MORNING AT MANY SOUTHERN TERMINALS. ANY RESTRICTIONS OVERNIGHT WILL BE HIGHLY DEPENDENT ON PLACEMENT AND AMOUNT OF RAINFALL TODAY. OUTLOOK.../FRIDAY THROUGH TUESDAY/... SEVERAL CROSSING DISTURBANCES WILL CAUSE PERIODIC RESTRICTIONS INTO THE WEEKEND...WITH VFR CONDITIONS EXPECTED MONDAY AND TUESDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
225 PM EDT THU AUG 21 2014 .SYNOPSIS... UNSETTLED WEATHER WILL CONTINUE THROUGH THE WEEKEND WITH OCCASIONAL SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH TONIGHT/... SHOWERS AND THUNDERSTORMS SUPPORTED BY UPPER LEVEL WAVE IS NOW MOVING ACROSS THE UPPER OHIO VALLEY. ADDED LIKELY POPS TO THE NORTH AS UPPER WAVE PASSES THROUGH IN THE AFTERNOON WITH COVERAGE OF CONVECTION EXPECTED TO INCREASE. VISIBLE SATELLITE IMAGERY SHOWS AMPLE CLOUD COVERAGE ACROSS PITTSBURGH AND SOUTH. HENCE...OPTIMAL DAYTIME HEATING WILL NOT OCCUR IN THAT REGION...HOWEVER...INCREASING MOISTURE WILL AID IN INSTABILITY YIELDING SHOWERS AND THUNDERSTORMS. TO THE NORTH...SUFFICIENT HEATING DUE TO LESS CLOUDS HAVE RAMPED UP INSTABILITY. RAP ANALYSIS SHOWS RELATIVELY STRONGER SHEAR IN THIS ZONE AS WELL. THEREFORE...ISOLATED STRONG TO MARGINALLY SEVERE STORMS ARE POSSIBLE THIS AFTERNOON NORTH OF PITTSBURGH. GREATER COVERAGE OF CONVECTION IS EXPECTED TO WANE LATER IN THE EVENING DUE TO LOSS OF HEATING. SOME SHOWERS MAY STILL LINGER ACROSS THE AREA OVERNIGHT DUE TO THE NEARLY STATIONARY SURFACE BOUNDARY. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... AS THE NEXT SHORTWAVE CROSSES THE REGION FROM A WEAKENING AND EXITING UPPER LOW...AXIS OF HEAVY RAINFALL WILL SHIFT EAST ON FRIDAY AS THE BOUNDARY BEGINS TO SLOWLY MOVE. UNCERTAINTY STILL EXISTS FOR ANY FLOODING AS MODELS ARE IN MINOR DISAGREEMENT FOR THE PLACEMENT OF HEAVY RAIN. USED MODEL BLEND OF GFS/NAM FOR POPS AND HPC FOR QPF. UPPER LEVEL RIDGE DEVELOPS THROUGH THE WEEKEND BRINGING SLIGHTLY WARMER THAN NORMAL TEMPERATURES. A FEW SHORTWAVES TOPPING THE RIDGE BRINGS THE CHANCE OF SHOWERS AND THUNDERSTORMS...AT LEAST FOR SATURDAY BUT OVERALL COVERAGE SHOULD BE SMALL. && .LONG TERM /MONDAY THROUGH THURSDAY/... MORE CLARITY EXISTS IN THE EXTENDED FORECAST WITH THE LATEST ROUND OF MODEL GUIDANCE. BY SUN THE SFC LOW FROM THE EARLY WEEKEND DEEPENS OVER THE PIEDMONT OF VA/NC PULLING THE DEEPER MOISTURE SOUTH WITH IT. IN THE MEANTIME...THE UPPER RIDGE CURRENTLY SETTING UP OVER THE SRN MS VALLEY WILL BUILD NORTH FURTHER WITH ITS AXIS SHIFTING EAST THROUGH SUN. THIS WILL WORK TO DEFLECT AN ADVANCING LOW PRESSURE SYSTEM WELL NORTH OF THE GREAT LAKES EARLY NEXT WEEK...RESULTING IN A WARMING AND DRYING TREND. TEMPERATURES SHOULD REMAIN AT OR EVEN JUST ABOVE AVERAGE INTO THE MIDDLE OF NEXT WEEK. TAX && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... STILL LOOKING AT THE BEST PRECIP CHANCES ACROSS NORTHERN WEST VIRGINIA AND SOUTHEAST OHIO THIS AFTERNOON...LESS TO THE NORTH. KEPT PREVAILING SHRA AT ZZV/MGW AND HAVE ONLY VCTS MENTIONED TO THE NORTH. IFR POSSIBLE IN ANY THUNDERSTORM. SHOULD SEE A DECREASE IN COVERAGE WITH LOSS OF HEATING DURING THE EVENING. PUT IN MVFR FOG AT SOME LOCATIONS LATE. WILL NEED TO WATCH EASTERN OHIO LATE TONIGHT FOR POSSIBLE INTRUSION OF MCS. ZZV WOULD HAVE THE BEST CHANCE OF BEING AFFECTED. OUTLOOK.../FRIDAY THROUGH MONDAY/... SEVERAL CROSSING DISTURBANCES WILL CAUSE PERIODIC RESTRICTIONS INTO THE WEEKEND. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION...UPDATE
NWS JACKSON MS
1030 AM CDT THU AUG 21 2014 .UPDATE...ROSE POPS SLIGHTLY THROUGH THE REST OF THE DAY IN MAINLY THE WESTERN HALF OF ZONES. IN SOME OF THOSE WESTERN ZONES ALSO LOWERED HIGH TEMPERATURE EXPECTATIONS A TOUCH. /BB/ && .DISCUSSION...VISIBLE SATELLITE ANALYSIS REVEALS A MESOSCALE CONVECTIVE VORT (MCV) LEFTOVER FROM YESTERDAYS CONVECTION CURRENTLY SPINNING OVER NE LA...EMBEDDED JUST TO THE WEST OF THE UPPER LEVEL HIGH CENTER AFFECTING THE LOWER MS VALLEY REGION. DESPITE THE PREVAILING RIDGE INFLUENCE...ISOLATED TO LOCALLY SCATTERED MIDDAY THROUGH AFTERNOON SHOWERS AND THUNDERSTORMS LOOK TO BE POSSIBLE ACROSS MAINLY THE WESTERN HALF OF ZONES OWING TO THE PRESENCE OF SAID MCV. LATEST HRRR PAINTS THIS PICTURE QUITE WELL ALTHOUGH IT IS POSSIBLE THOSE SOLUTIONS ARE A LITTLE OVERDONE. EXPECTING CLOUDS/PCPN TO KEEP TEMPS DOWN A LITTLE IN WESTERN ZONES SO MAX READINGS DROPPED THERE A DEGREE OR TWO. MORNING WET MICROBURST CHECKLIST SUGGESTED MODERATE POTENTIAL FOR LOCALLY SEVERE DOWNBURSTS GIVEN TEMPERATURES IN THE MID 90S SO CONVECTION WILL BE MONITORED CLOSELY FROM THAT STANDPOINT...ALTHOUGH POTENTIAL STILL NOT DEEMED HIGH ENOUGH TO INCLUDE MENTION IN THE HWO. /BB/ && .PREV DISCUSSION... /ISSUED 400 AM CDT THU AUG 21 2014/ SHORT TERM...TODAY THROUGH FRIDAY NIGHT...A LITTLE WARMER EACH DAY WITH AFTERNOON HEAT INDEX VALUES REMAINING THE MAIN CONCERN. EARLY MORNING SURFACE ANALYSIS HAD A 1019MB RIDGE CENTERED OVER THE GULF COAST. EARLY MORNING WATER VAPOR IMAGERY/RUC ANALYSIS SHOWED THE CIRCULATION AROUND A 592DAM HIGH CENTERED OVER OUR AREA. THIS MID LEVEL HIGH WILL STRENGTHEN FURTHER TODAY AND REMAIN CENTERED OVER OUR CWA THROUGH FRIDAY NIGHT. TOGETHER RIDGING SURFACE AND ALOFT OVER OUR REGION WILL ALLOW FOR A SLOW WARMING TREND INTO THE WEEKEND. A RATHER MOIST AIRMASS WILL REMAIN OVER OUR AREA WITH PWS OF AN INCH AND THREE QUARTERS TO TWO INCHES. THIS WILL HELP MAINTAIN UPPER 60 TO LOWER 70 DEGREE DEW POINTS DURING THE HOTTEST PART OF THE DAY. THE COMBINATION OF TEMPERATURES IN THE MID TO UPPER 90S WITH THE HIGH RELATIVE HUMIDITY WILL RESULT IN MAXIMUM HEAT INDEX VALUES OF 101-104F TODAY AND 102-106 FRIDAY. GFSMOS GUIDANCE WAS AGAIN A LITTLE TOO WARM AND LEANED TOWARD A BLEND OF THE NAM AND ECMWF MOS GUIDANCE FOR AFTERNOON HIGHS EACH DAY. MODEL CONSENSUS STILL HINTS AT LATE AFTERNOON SEA BREEZE CONVECTION TRYING TO DRIFT UP INTO OUR SOUTHERN ZONES. HAVE CARRIED ISOLATED WORDING IN THE SOUTHWEST TODAY AND ONLY IN OUR SOUTHEAST MOST ZONES FRIDAY AFTERNOON. RAIN CHANCES WILL REMAIN VERY LOW ELSEWHERE THROUGH THE PERIOD. /22/ LONG TERM...SATURDAY THROUGH WEDNESDAY...THROUGH THE WEEKEND HEAT AND HUMIDITY WILL BE BE THE PRIMARY ISSUE AS MEAN RIDGING CONTINUES THROUGH SUNDAY...WHICH WILL BRING CLASSIC AUGUST SUMMER MUGGY CONDITIONS. 850MB TEMPS WILL BE IN THE UPPER 20S TO AROUND 30C. THIS WILL BRING TEMPS IN THE MID TO UPPER 90S THROUGH THE WEEKEND. WITH LOWS IN THE 70S HEAT INDICES WILL BE A CONCERN. HEAT INDICES WILL BE AROUND 100 TO 107 ON SATURDAY AND SUNDAY. WITH STRONG SUBSIDENCE RAIN CHANCES WILL BE RATHER SCARCE THROUGH SUNDAY. AS WE GO INTO NEXT WEEK MOISTURE WILL BUILD ACROSS THE REGION FROM THE EAST. THIS WILL GIVE THE REGION A BREAK IN WARM AFTERNOON HIGH TEMPERATURES. THUS 850MB TEMPS WILL COOL SOME INTO THE MIDDLE 20SC. RAIN CHANCES WILL PICK UP AS DEEP TROPICAL MOISTURE BUILDS ACROSS THE REGION. PWATS WILL INCREASE TO AROUND 2.2 INCHES. THERE WILL BE DECENT INSTABILITY FOR SOME CONVECTIVE CHANCES FROM MONDAY THROUGH WEDNESDAY WITH SOME LOCALLY HEAVY RAINFALL POTENTIAL. THE MEAN RIDGING WILL FLUCTUATE SOME DURING THE UPCOMING WORK WEEK. AS FAR AS THE TROPICS ARE CONCERN MODELS ARE KEEPING TROPICAL SYSTEMS AWAY FROM THE GULF OF MEXICO AND PUSHING POSSIBLE TROPICAL SYSTEMS OFF THE EAST COAST. AS FAR AS MODEL DIFFERENCES ARE CONCERN MOST OF THE ENSEMBLES... EURO...NAVY AND UK MODELS KEEP THE MEAN RIDGE DOMINANT OVER OUR REGION. THE GFS TRIED TO BRING AN UPPER TROUGH OVER THE CENTRAL PLAINS AND EVENTUALLY PUSHED A FRONT TOWARD THE REGION FOR THE LATER PART OF THE WORK WEEK...WHICH SEEMS TO BE AN OUTLIER. MODELS WERE IN GENERAL AGREEMENT WITH THE WEEKEND HEAT AND INCREASE IN TROPICAL MOISTURE FROM THE EAST FOR NEXT WEEK. AS FAR AS POPS AND TEMPS ARE CONCERN WENT CLOSE TO MEX AND GMOS GUIDANCE FOR THE PERIOD./17/ && .AVIATION...VFR CONDS CURRENTLY PREVAIL AT ALL TAF SITES AND WILL CONTINUE AT MOST INTO THE EVENING. ISOLATED SHOWERS/STORMS ARE PSBL AT MAINLY IN W TO SW MS...WHICH COULD BRING DOWN KGLH/KJAN TO MVFR/IFR CEILINGS BRIEFLY AROUND 20-23Z. WINDS WILL BE LIGHT MAINLY FROM THE W TO SW AROUND 4-8KTS THIS AFTERNOON. /DC/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 96 73 97 73 / 14 6 7 5 MERIDIAN 96 72 97 73 / 8 6 9 5 VICKSBURG 94 73 97 72 / 26 6 5 4 HATTIESBURG 97 73 98 74 / 14 12 20 9 NATCHEZ 92 74 95 73 / 33 11 13 10 GREENVILLE 95 74 97 74 / 11 5 5 4 GREENWOOD 96 73 97 73 / 8 5 5 4 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ BB/DC/22/17
AREA FORECAST DISCUSSION
NWS BILLINGS MT
854 PM MDT FRI AUG 22 2014 .UPDATE... A LONE SEVERE STORM IMPACTED SOUTHEAST MT A LITTLE WEST OF BROADUS EARLIER THIS EVENING. THIS HAS DISSIPATED AND CONVECTION IS FOCUSED IN SOUTHERN CARTER COUNTY NOW...AND IS NOT EXPECTED TO BECOME SEVERE. SHOWER ACTIVITY IS GRADUALLY BECOMING MORE WIDESPREAD ACROSS THE CWA IN RESPONSE TO INCREASING LARGE SCALE ASCENT WITH DEEP TROF DIGGING INTO IDAHO. LATEST H3 ANALYSIS SHOWS A VERY IMPRESSIVE 100 KT JET FROM OREGON INTO NEVADA...WITH STRONG DIFFLUENCE SHOWN ON SATELLITE IMAGERY FROM UTAH INTO SOUTHEAST IDAHO. ASCENT FROM THE UPPER LOW WILL ONLY INCREASE THROUGH THE NIGHT...AND IN FACT PER LATEST BLX VAD WINDS WE ARE SEEING EASTERLY UPSLOPE WINDS THROUGH 10KFT NOW. VERY IMPRESSIVE DYNAMICS FOR THE THIRD WEEK IN AUGUST. THERE REMAINS SOME UNCERTAINTY REGARDING TRACK OF MID LEVEL LOW BY EARLY SATURDAY MORNING WITH THE LATEST RAP SHOWING A WEAK 700MB LOW JUST NORTH OF BILLINGS...AND THIS IS NOT TOO DISSIMILAR TO THE NEW 00Z NAM...WITH THE GFS BEING A BIT FURTHER NORTH. SO AFTER A GOOD PERIOD OF RAIN TONIGHT WE MAY SEE THE HEAVIER PCPN SHIFT TO MAINLY OUR NORTH AND EAST PARTS FOR TOMORROW. THAT BEING SAID... RAP SHOWS 300MB LOW OVER SOUTHEAST IDAHO SATURDAY MORNING WHICH PUTS OUR AREA IN A VERY DIFFLUENT FLOW ALOFT...SO FEEL EVEN WITH SOME DEGREE OF LOW LEVEL DOWNSLOPING BY SATURDAY MORNING WE WILL STILL SEE ENOUGH ASCENT FOR SHOWERS IN THE BILLINGS AREA. INSTABILITY SHOULD REMAIN GREAT ENOUGH FOR EMBEDDED SCATTERED THUNDERSTORMS IN OUR EAST...OTHERWISE WE ARE LOOKING AT SHOWERS W/ ONLY ISOLD TSTMS THROUGH TOMORROW. FOR THE UPDATE HAVE RAISED POPS A BIT MORE ACROSS MUCH OF THE AREA TONIGHT AND SATURDAY. OVERALL FORECAST REMAINS ON TRACK. ITS GOING TO BE WET FOLKS. JKL && .SHORT TERM...VALID FOR SAT AND SUN... BROAD UPPER TROUGH OVER THE PACIFIC NW WILL CONTINUE TO PRODUCE AN UNUSUALLY COOL AND WET PERIOD ACROSS OUR REGION THE NEXT COUPLE OF DAYS. IF I WERE TO PICK A WETTEST PERIOD...IT WOULD BE TONIGHT INTO SATURDAY MORNING AS PLENTY OF LIFT IS PROGGED OVER OUR FORECAST AREA. ASSOCIATED JET DYNAMICS AND STRONG ISENTROPIC LIFT OUT IN FRONT OF THE UPPER TROUGH WILL LIKELY PRODUCE WIDESPREAD RAIN AND EMBEDDED THUNDER OVER THE AREA. SOME DISCRETE STRONG THUNDERSTORM CELLS ARE ALSO POSSIBLE FROM SHERIDAN TO CARTER COUNTY THIS EVENING AS EFFECTIVE SHEAR INCREASES ACROSS THIS AREA WITH A JET STREAK ALOFT. ONE OR TWO STRONG TO SEVERE STORMS ARE POSSIBLE IN THIS AREA DUE TO THE INCREASING POSSIBILITY OF SUSTAINED UPDRAFTS. LOOK FOR A VERY MOIST ATMOSPHERE WITH AREAS OF FOG AND LIGHT RAIN OVERNIGHT. SATURDAY...NEGATIVE TILT TROUGH WORKS INTO THE REGION FROM THE WEST AND MAY PRODUCE SOME STRONG TO SEVERE STORMS IN THE SE CORNER OF THE STATE DUE TO STRONG SHEAR AND INSTABILITY/LIFT. SEVERAL POCKETS OF LIFT WILL PRODUCE AREAS OF RAIN...MAINLY OVER THE NORTHERN AND EASTERN ZONES THROUGH SATURDAY. BY SATURDAY EVENING AS THE UPPER LOW MOVES OVER THERE IS SOME HINT OF DOWNSLOPE DRYING FROM HARLOWTON TO YELLOWSTONE COUNTY DUE TO NORTH/NORTHWEST FLOW WRAPPING AROUND THE LOW PRESSURE SYSTEM. THE ECMWF WANTS TO KEEP A CLOSED UPPER LOW OVER SE MONTANA WHILE THE GFS LIFTS THE SYSTEM NORTH. THE ECMWF VERSION IS MUCH WETTER THAN THE GFS. THERE IS NO REAL WAY TO DISCERN WHICH SOLUTION IS MOST ACCURATE AT THIS TIME ...THOUGH THE GFS HAS SUPPORT FROM THE NAM...AND GFS ENSEMBLE SPREADS ARE NOT THAT WIDE. THEREFORE...I HAVE BLENDED THE WET/DRY SOLUTIONS BUT LEANED A BIT MORE ON THE LESS WET GFS SOLUTION GOING INTO SUNDAY. LOOK FOR A BLUSTERY SATURDAY NIGHT AND SUNDAY WITH NORTH WINDS 15 TO 25 MPH COMBINED WITH THE RAINY CONDITIONS. BY SUNDAY NIGHT THE UPPER LOW IS TRACKING ACROSS NORTH DAKOTA WITH A MID LEVEL ZONAL FLOW SPREADING OVER MONTANA AND GENERALLY BRINGING MOST OF THE PRECIPITATION TO AN END OVER OUR FORECAST AREA. BT .LONG TERM...VALID FOR MON...TUE...WED...THU...FRI... MINIMAL UPDATES THIS AFTERNOON FOR THE INHERITED EXTENDED FORECAST...WITH MODELS IN GOOD AGREEMENT THROUGHOUT THE PERIOD. A SECONDARY LOBE OF THE BROAD UPPER TROF IS STILL VERY SLOW TO PUSH OFF TO THE EAST. THE TROF AXIS WILL BEGIN SLOW PROGRESSION EASTWARD MONDAY. THIS WILL BRING ANOTHER ROUND OF PRECIP THROUGH THE REGION BEGINNING MONDAY...AND LINGERING THROUGH MUCH OF TUESDAY. THE DYNAMICS FOR THIS SYSTEM APPEARS MUCH WEAKER...SO EXPECT SHOWERS AND THUNDERSTORMS TO BE MORE SCATTERED IN NATURE. THE SLOW MOVEMENT OF THE TROF WILL KEEP TEMPS WELL BELOW SEASONAL AVERAGE...WITH HIGHS IN THE LOW TO MID 70S EACH DAY. AN UPPER LEVEL RIDGE BEGINS BUILDING INTO THE REGION OVERNIGHT TUESDAY NIGHT...AND IS THEN FOLLOWED BY ZONAL FLOW DEVELOPING LATE THURSDAY. THEREFORE EXPECT WARMER AND DRIER CONDITIONS TO PREVAIL THROUGH THE REMAINDER OF THE EXTENDED PERIOD. TEMPERATURES WILL SLOWLY TREND UPWARD...BUT GENERALLY REMAIN AROUND SEASONAL AVERAGE. AAG && .AVIATION... SCATTERED SHOWERS...AND A FEW THUNDERSTORMS...WILL IMPACT ALL TERMINALS TONIGHT. EXPECTING MVFR AND IFR CONDITIONS WITH OCCASIONAL HEAVY RAINFALL THROUGH THE NIGHTTIME HOURS. CEILINGS WILL REMAIN LOW UNTIL THE DAYBREAK HOURS. SINGER && .PRELIMINARY POINT TEMP/POPS... SAT SUN MON TUE WED THU FRI ----------------------------------------------------------- BIL 056/063 049/065 048/071 050/075 053/082 057/087 061/085 +8/T 44/T 23/T 32/T 11/U 01/U 11/U LVM 051/060 045/064 042/070 044/075 048/083 051/086 051/084 +8/T 43/T 25/T 52/T 11/B 01/U 12/T HDN 057/068 050/066 046/074 050/077 051/083 055/088 059/088 98/T 55/T 13/T 32/T 11/U 01/U 11/U MLS 060/067 052/062 047/071 051/074 053/082 057/087 062/090 ++/T 86/T 22/T 22/T 11/U 11/U 11/B 4BQ 060/071 051/064 046/071 052/073 051/081 056/087 060/089 89/T 63/T 22/T 33/T 11/U 11/U 11/U BHK 056/066 050/061 046/069 047/071 048/078 053/083 059/086 9+/T 86/T 22/T 23/T 11/U 11/U 11/B SHR 055/070 047/065 044/073 048/074 048/081 051/087 055/089 76/T 53/T 13/T 43/T 11/U 01/U 11/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
636 PM CDT FRI AUG 22 2014 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 256 PM CDT FRI AUG 22 2014 THE HIGHLIGHT OF THE SHORT TERM PERIOD WILL BE THE FACT WE ARE EXPECTING THUNDERSTORMS TODAY/TONIGHT. THERE STILL REMAINS SOME UNCERTAINTY FOR TIMING...LOCATION...AND OVERALL DEVELOPMENT. THE WARM FRONT TO OUR SOUTH...WHICH IS SITUATED OVER THE KANSAS/NEBRASKA BORDER...IS JUST MOSEYING ALONG TODAY AND HAS CAUSED SOME CONCERN FOR DEVELOPMENT. SHOWERS/STORMS SHOULD DEVELOP ALONG THIS BOUNDARY AS THE CAP BEGINS TO BREAK. SPC MESOSCALE ANALYSIS PAGE HAS US CAPPED UNTIL ABOUT 22-23Z. AT THIS TIME WE SHOULD SEE THE BEGINNING STAGES FOR INITIATION ALONG THE BOUNDARY TO OUR SOUTH. AMPLE INSTABILITY OF ABOUT 2000-3000 J/KG WILL BE IN PLACE...DUE TO A VERY MOIST BOUNDARY LAYER AND STEEP LAPSE RATES. MOST UNSTABLE CAPE COULD BE AS HIGH AS 4000 J/KG. BULK SHEAR 0-6 KM WILL BE AROUND 30 KNOTS...AND THIS IS NOT TOO IMPRESSIVE...HOWEVER...LOW LEVEL SHEAR WILL BE STRONG. EARLIER RUNS OF THE RAP INDICATED HELICITY VALUES NEAR 400 M2/S2 WOULD BE IN PLACE AROUND 23Z FOR WESTERN PORTIONS OF THE CWA. THESE VALUES WILL PUSH EASTWARD THROUGH THE AFTERNOON/EVENING. THESE LOW LEVEL HELICITY VALUES COUPLED WITH AMPLE INSTABILITY WILL POSE A THREAT FOR SOME ISOLATED TORNADOES...MAINLY FOR OUR NEBRASKA COUNTIES. WITH THAT BEING...WIND AND HAIL WILL BE THE MAIN THREATS TODAY/TONIGHT. THE BEST CHANCE FOR SEVERE WEATHER WILL BE ACROSS OUR NEBRASKA COUNTIES...BUT THE ENTIRE CWA DOES HAVE THE POTENTIAL FOR SEVERE WEATHER. I DO EXPECT THUNDERSTORM ACTIVITY TO KICK INTO GEAR AROUND 6 OR 7 PM...IF NOT SOONER. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 256 PM CDT FRI AUG 22 2014 VARIOUS RAIN CHANCES FOR THE WEEKEND AND IN TO THE FIRST PART OF THE WORK WEEK...ALONG WITH FLUCTUATING TEMPERATURES ARE PRIMARY FORECAST CONCERNS. WILL KEEP THIS FAIRLY SHORT DUE TO POSSIBLE SEVERE WEATHER DEVELOPING LATER THIS AFTERNOON. STARTING OUT SATURDAY EVENING IN THE MID/UPPER LEVELS...THERE SHOULD BE A LARGE AMPLITUDE TROUGH OVER THE ROCKIES WITH A CLOSED LOW SITUATED OVER EAST CENTRAL MONTANA...AS THE CURRENT SYSTEM OVER THE PACIFIC NW DRIFTS EASTWARD. THIS WILL PUSH THE RIDGE A LITTLE EAST AS WELL WITH THE AXIS STRETCHING FROM LAKE SUPERIOR TO MISSISSIPPI. THE BETTER FORCING WITH THE LOW PRESSURE SHOULD BE TO THE WEST AND NORTH OF OUR REGION. AT THE SURFACE...EXPECT A FRONTAL BOUNDARY TO BE TO OUR NORTH ACROSS SDAK AT 00Z AND THEN THIS WILL PUSH INTO OUR AREA BY SUNDAY MORNING. HAS NOT TAKEN A WHOLE LOT TO SET OFF CONVECTION THE PAST WEEK AND WHILE THE SET UP FOR SATURDAY NIGHT IS NOT AS GOOD AS TONIGHT...WILL PROBABLY STILL NEED SOME LOW POPS GIVEN APPROACHING WEAK COLD FRONT AND ANTICIPATED LOW LEVEL JET. PREVIOUS SHIFT AFD NOTED SOME HEAT BURST POTENTIAL WITH ANY THUNDERSTORMS THAT DO DEVELOP AND THIS SCENARIO STILL IN PLACE. WEATHER SHOULD BE QUIET DURING THE DAYTIME ON SUNDAY BEHIND THE COLD FRONT AND POSSIBLE SUNDAY NIGHT ALTHOUGH BOTH THE NAM AND GFS ARE DEVELOPING SOME PRECIPITATION TO THE WEST AND MOVING ACROSS THE CWA SUNDAY NIGHT. GFS APPEARS TO OVERDEVELOP A VORTICITY MAX ALTHOUGH DIFFICULT TO TOTALLY DISCOUNT WITH CYCLONIC FLOW IN UPPER LEVELS. MONDAY NIGHT AND TUESDAY NIGHT STILL LOOK ACTIVE AS YET ANOTHER HIGH AMPLITUDE TROUGH IS SLATED TO MOVE ACROSS THE ROCKIES AND INTO THE PLAINS. AT THE SURFACE AN EAST/WEST STATIONARY FRONT WILL HANG OUT OVER THE AREA RESULTING IN THE CLASSIC NIGHTTIME RAIN EVENTS. BY WEDNESDAY THE EXTENDED MODELS IN DECENT AGREEMENT IN PUSHING THE TROUGH EAST THROUGH THE CWA WITH RIDING THEN MOVING IN TO QUIET THINGS DOWN FOR THE REMAINDER OF THE WEEK. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 623 PM CDT FRI AUG 22 2014 VFR CONDITIONS ARE EXPECTED AT THE TAF SITES THROUGH MOST OF THE VALID PERIOD. THE MAIN CONCERN WILL BE THUNDERSTORM ACTIVITY LATER THIS EVENING. ONCE CONVECTION STARTS...CEILINGS AND VISIBILITIES WILL BE REDUCED WITH ANY ONGOING THUNDERSTORM ACTIVITY. GUSTY WINDS WILL ALSO BE A THREAT TO THE TERMINAL SITES ONCE THUNDERSTORMS BEGIN. WE DO EXPECT THUNDERSTORMS TO BEGIN AROUND 01Z- 02Z. CHANCES ARE THUNDERSTORMS WILL BE ONGOING FOR SEVERAL HOURS BEFORE CONDITIONS IMPROVE AGAIN. THERE IS SOME UNCERTAINTY STILL AT THIS POINT...BUT CONFIDENCE WAS HIGH ENOUGH TO PLACE THUNDERSTORMS IN THE TAF AT THIS TIME. WIND SHEAR IS CURRENTLY IN THE TAF AS WELL...AND IT LOOKS LIKE THERE COULD BE LLWS OF ABOUT 30 KNOTS AT ABOUT 1000 FT...TO ABOUT 40 KNOTS AT 2500 FT. THE WINDOW FOR LLWS WILL RANGE FROM ABOUT 07Z TO ABOUT 12Z. CONFIDENCE IS NOT ENTIRELY HIGH FOR THIS TO BE REALIZED BECAUSE ONE SET OF GUIDANCE IS NOW SUGGESTING NO LLWS AT ALL. WITH THAT BEING SAID...THERE IS ENOUGH EVIDENCE OF LLWS TO INTRODUCE THIS INTO THE TAF. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...GUERRERO LONG TERM...EWALD AVIATION...GUERRERO
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
357 AM CDT THU AUG 21 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 356 AM CDT THU AUG 21 2014 MODELS IN FAIR AGREEMENT IN NEAR TERM AND WILL USE A BLEND FOR THE FORECAST. UPPER HIGH PARKED OVER LOUISIANA THIS MORNING WITH CLOSED LOW OVER PACIFIC NORTHWEST AND TROUGH THROUGH THE DESERT SOUTHWEST. WESTERN NEBRASKA CONTINUES IN THE RING OF FIRE BETWEEN FEATURES. ONGOING PRECIPITATION THIS MORNING LOOKS TO LINGER THROUGH THE MORNING WITH CLUSTER OF STORMS OVER NORTHEAST COLORADO BRINGING CHANCES OF PRECIPITATION TO SOUTHWEST AND THE SOUTHEAST NEBRASKA PANHANDLE. HAVE RETAINED SLIGHT CHANCES FOR ISOLATED SHOWERS AND THUNDERSTORMS. AS THE DISTURBANCE ON SATELLITE MOVES ACROSS WESTERN NEBRASKA EARLY THIS MORNING SHOWERS TO END. PARTLY CLOUDY SKIES TODAY WITH SURFACE LOW OVER NORTH CENTRAL KANSAS. WOULD EXPECT BEST CHANCES FOR THUNDERSTORM DEVELOPMENT OVER THE NEBRASKA PANHANDLE AND NORTHEAST COLORADO LATE THIS AFTERNOON WITH HEATING OF THE DAY AND WEAK WAVE MOVING THROUGH SOUTHWEST FLOW OUT OF THE BOTTOM OF THE TROUGH TO THE WEST. HIGHS TODAY AROUND 90 OVER WESTERN NEBRASKA. TONIGHT SLIGHT CHANCES RETAINED FOR THUNDERSTORMS OVER THE WEST AND SOUTHWEST. NO MAJOR WAVES MOVING THROUGH SOUTHWEST FLOW BUT A COLD FRONT WILL MOVE INTO WESTERN SOUTH DAKOTA AND INTO SOUTHWEST SOUTH DAKOTA TONIGHT. SOUTHWEST FLOW WILL KEEP TEMPERATURES IN THE MID 60S OVER NIGHT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 356 AM CDT THU AUG 21 2014 MODELS IN GOOD AGREEMENT FOR THE WEEKEND AS COOLER CONDITIONS ARRIVE...HOWEVER DIFFERENCE DEVELOP BY MIDWEEK WITH RETURN OF WARMER TEMPS. FRIDAY INTO SATURDAY WILL SEE A TROUGH DEEPEN ACROSS THE PACIFIC NORTHWEST AS A RIDGE AMPLIFIES ACROSS THE MISS RVR VALLEY. THE SOUTHWEST FLOW WILL TAP THE PACIFIC MONSOON FLOW WITH POPS LIKELY EARLY IN THE WEEKEND. PARTLY TO MOSTLY CLOUDY SKIES AND PERIODIC CHANCES FOR RAIN WILL HOLD TEMPS IN THE 70S TO LOWER 80S...HOWEVER EXPECT A FEW BREAKS IN THE CLOUDS AND WILL ALLOW TEMPS TO SURGE INTO THE 80S FOR MOST AREAS. SOME CONCERNS ON TEMPS AS CLOUDS COULD HOLD STRONG WITH NO BREAKS AND KEEP TEMPS LOWER. SUNDAY INTO THE FIRST OF THE WEEK THE TROUGH WILL CROSS THE ROCKIES AND PUSH ONTO THE NORTHERN PLAINS. A COLD FRONT WILL PUSH ACROSS THE CWA SUNDAY WITH COOLER CONDITIONS EXPECTED...GENERALLY 70S TO AROUND 80 IN THE SW. WILL ALSO SEE LOW CHANCES FOR RAINFALL AS A COUPLE OF DISTURBANCES ROTATE AROUND THE NORTHERN LOW. MODELS THEN DIVERGE AS THE ECMWF HAS SHIFTED FROM RECENT TRENDS...BRINGING WARMER AIR QUICKLY BACK TO THE REGION. THE GFS REMAINS CONSISTENT WITH THE COOLER CONDITIONS ACROSS THE HIGH PLAINS. WILL FOLLOW CLOSER TO THE PERSISTENT FORECAST AND THE GFS...AND WAIT TO SEE IF THE WARMER EC SOLUTION GETS ADDITIONAL SUPPORT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1128 PM CDT WED AUG 20 2014 INDICATIONS FROM THE HRRR AND NAM MODELS SUGGEST THE ONGOING CONVECTION COULD LAST SEVERAL MORE HOURS AS IT SHIFTS SLOWLY EAST OVERNIGHT EXITING BY 12Z. VFR IS EXPECTED ALL AREAS THEREAFTER. STRONG WINDS ALOFT AND VERY UNSTABLE AIR LATE THURSDAY AFTERNOON AND EVENING WOULD LIKELY CAUSE TSTM DEVELOPMENT ONCE AGAIN EXCEPT THE MODELS SUGGEST LITTLE IN THE WAY OF AN UPPER LEVEL DISTURBANCE. SO POPS ARE ISOLATED LATE THURSDAY IN THE WEST AND ALONG OR EAST OF HIGHWAY 83. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...POWER LONG TERM...MASEK AVIATION...CDC
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1148 PM CDT WED AUG 20 2014 .SHORT TERM...(TONIGHT THROUGH SATURDAY) ISSUED AT 334 PM CDT WED AUG 20 2014 UNSETTLED WEATHER PATTERN WILL REMAIN IN PLACE OVER THE NEXT WEEK WITH SEVERAL OPPORTUNITIES FOR THUNDERSTORMS. TIMING THESE CHANCES ALONG WITH INCREASE IN HEAT AND HUMIDITY ARE THE PRIMARY FORECAST CONCERNS. MORNING UPPER AIR CHARTS SHOWED MID LEVEL TROUGH EXTENDING FROM THE CANADIAN ROCKIES INTO SOUTHERN CALIFORNIA...WITH SOUTHWEST FLOW AHEAD OF THE TROUGH RIDING INTO THE NORTHERN PLAINS. UPPER RIDGE AXIS WAS CURRENTLY OVER THE MISSOURI RIVER VALLEY...BUT IS FORECAST TO SHIFT EAST AND FLATTEN A BIT ON THURSDAY. THIS WILL LEAVE OUR AREA UNDER SOUTHWEST FLOW ALOFT...WITH PATH FOR EJECTING SHORTWAVES OVER NEBRASKA AND THE DAKOTAS. ALSO OF NOTE WAS PLUME OF MID LEVEL MOISTURE EXTENDING FROM THE SOUTHERN BAJA INTO WESTERN KANSAS AND SOUTHWEST NEBRASKA. WITH ONLY A SLOW DRIFT TO WESTERN TROUGH...EXPECT THIS MOISTURE PLUME TO EXPAND OVER EASTERN NEBRASKA AND WESTERN IOWA AND REMAIN IN PLACE AT LEAST INTO THE WEEKEND. USING 700MB DEW POINT TEMPERATURES AS A PROXY...MODELS CONCUR WITH THIS EXPECTATION. THE RESULT OF THESE PARAMETERS WILL BE AN ATMOSPHERE PRIMED FOR SCATTERED CONVECTION AS SHORTWAVES ROLL INTO THE PLAINS. TIMING OF THOSE SHORTWAVES WILL PROVE DIFFICULT MORE THAN A DAY TO TWO OUT. HOWEVER MODELS AGREE ON A SIGNIFICANT SHORTWAVE MOVING INTO THE PLAINS FRIDAY NIGHT...OUR MOST LIKELY TIME FOR WIDESPREAD HEAVY RAINS. FOR TONIGHT...WATER VAPOR LOOPS IMPLY A SHORTWAVE IN WESTERN KANSAS THIS AFTERNOON...EXPECTED TO LIFT NORTHEAST ACROSS OUR CWA LATER THIS EVENING AND OVERNIGHT. GREATER THAN 7 C/KM MID LEVEL LAPSE RATES WILL BE IN PLACE ALONG WITH ABUNDANT MID LEVEL MOISTURE. EXPECT SCATTERED THUNDERSTORMS TO FIRE AFTER MIDNIGHT WHEN LOW LEVEL JET KICKS UP TO 35KT WITH APPROACH OF SHORTWAVE. MAIN AREA OF CONCERN WILL BE OVER OUR NORTHERN CWA THEN. HOWEVER THIS EVENING...CONVECTION FROM EARLIER THIS MORNING MOVING ACROSS IOWA LAID DOWN AN OUTFLOW BOUNDARY WHICH MOVED INTO SOUTHWEST IOWA AND NORTHERN MISSOURI. VISIBLE SATELLITE PICS SHOW A LINE OF CUMULUS ALONG THIS BOUNDARY...AND RAP MODEL SUGGESTS MLCAPE IS APPROACHING 3500 J/KG IN NORTHWEST MISSOURI ALONG WITH DIMINISHING CAP. LATEST RAP AND HRRR FORECASTS KEEP CONVECTION IN CHECK THERE...BUT HAVE ADDED SMALL POPS FOR SEVERAL HOURS THIS EVENING. OVERNIGHT CONVECTION SHOULD BE EXITING THE CWA OR DIMINISHING BY MID MORNING. EXPECT CLOUDS TO CLEAR ALLOWING FOR PLENTY OF INSOLATION IN THE AFTERNOON WITH TEMPERATURES WELL INTO THE 90S AND DEW POINTS CLOSE TO 70. A WEAK FRONTAL BOUNDARY IS FORECAST TO SETTLE INTO NORTHEAST NEBRASKA THURSDAY AFTERNOON BEHIND WEDNESDAY NIGHT SHORTWAVE...AND COULD FOCUS THUNDERSTORM CHANCES THERE. RELATIVELY WARM TEMPERATURES ALOFT WILL LIKELY SUPPRESS CONVECTION IN THE AFTERNOON...WITH BETTER CHANCES COMING LATER IN THE EVENING AS THE FRONT SETTLES SOUTH INTO SOUTHEAST NEBRASKA AND SOUTHWEST IOWA AND MID LEVEL TEMPERATURES COOL A BIT. CONTINUED ISENTROPIC UPGLIDE OVER FRONTAL BOUNDARY IN MOIST ATMOSPHERE SUGGESTS AT LEAST SCATTERED CONVECTION IS POSSIBLE THROUGH THE NIGHT. MOST OF DAY FRIDAY SHOULD BE DRY AFTER MORNING STORMS IN THE SOUTH MOVE OFF TO THE EAST. FRONTAL BOUNDARY WILL BEGIN LIFTING TO THE NORTH DURING THE DAY WITH APPROACH OF STRONG SHORTWAVE FRIDAY NIGHT. INSTABILITY FORECASTS SHOW 2000-3000 J/KG OF SURFACE-BASED CAPE FRIDAY AFTERNOON...BUT SOUNDINGS SUGGEST A MODEST CAP WILL HOLD OFF STORMS UNTIL NEAR 00Z OR PROBABLY AFTER. CHANCES INCREASE MARKEDLY FRIDAY NIGHT AS SHORTWAVE AND SURFACE LOW MOVE NORTHEAST THROUGH THE CWA. CURRENT TRACK PLACES NORTHEAST NEBRASKA IN THE CORRIDOR OF HEAVIEST POTENTIAL RAINFALL WHERE PRECIPITABLE WATER WILL LIKELY EXCEED 2 INCHES. CURRENT HPC QPF PROGS PAINT ABOUT THREE-QUARTERS OF AN INCH OF RAIN IN NORTHEAST NEBRASKA...BUT WILL LIKELY SEE MUCH MORE THAN THAT IN LOCAL AREAS GIVEN MOISTURE AVAILABLE AND POTENTIAL FOR TRAINING OF STORMS. EXPECT ACTIVITY TO BE EXITING TO OUR NORTHEAST SATURDAY MORNING...BUT LEFTOVER BAROCLINIC ZONE AND WIND SHIFT WILL REMAIN IN PLACE FOR THE POTENTIAL FOR MORE STORMS LATER IN THE DAY SATURDAY. WILL MAINTAIN A SMALL CHANCE FOR ADDITIONAL AFTERNOON STORMS...EXPECTING SUBSIDENCE BEHIND EXITING SHORTWAVE TO SUPPRESS CONVECTION MOST OF THE AFTERNOON. .LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 334 PM CDT WED AUG 20 2014 CONTINUED CHANCES OF THUNDERSTORMS WILL REMAIN JUST ABOUT EACH PERIOD IN THE LONGER TERM FORECAST THROUGH WEDNESDAY. WESTERN UPPER TROUGH WILL SLOWLY DRIFT FROM THE ROCKIES SATURDAY NIGHT INTO THE PLAINS BY WEDNESDAY. ECMWF IS A LITTLE MORE PROGRESSIVE THAN THE GFS WITH THIS MOVEMENT...BUT EVEN THE ECMWF LEAVES SOME SEMBLANCE OF A TROUGH/LOW IN THE PLAINS THEN. USING A BLEND OF ECMWF AND GFS...AND WHERE SOME CONSISTENCY IS SHOWN...BEST CHANCES FOR MORE WIDESPREAD CONVECTION IS EXPECTED MONDAY NIGHT INTO TUESDAY...THEN AGAIN TUESDAY NIGHT INTO WEDNESDAY. BEFORE THEN...IMPULSES RIDING THROUGH MID LEVEL FLOW COULD SPARK AREAS OF STORMS AT JUST ABOUT ANY TIME AS FRONTAL BOUNDARY MEANDERS NORTH AND SOUTH THROUGH THE CWA AHEAD OF AND BEHIND EACH WAVE. TEMPERATURES SHOULD MODERATE SOME THROUGH THE PERIOD...BEGINNING WITH SUNDAY IN THE 80S TO NEAR 90...THEN RANGING FROM THE UPPER 70S TO MIDDLE 80S MONDAY THROUGH WEDNESDAY. && .AVIATION...(06Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1148 PM CDT WED AUG 20 2014 VFR CONDITIONS ARE EXPECTED AT THE TAF SITES. A FEW SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA DURING AROUND SUNRISE...HOWEVER CONFIDENCE IS FAIRLY LOW. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...DERGAN LONG TERM...DERGAN AVIATION...KERN
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1132 PM CDT WED AUG 20 2014 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 354 PM CDT WED AUG 20 2014 RATHER DIFFICULT FORECAST TONIGHT. THERE HAVE BEEN LOTS OF MID LEVEL CLOUDS HANGING ACROSS THE AREA THIS AFTERNOON...AND HAVE KEPT TEMPERATURES DOWN A BIT. CLOUDS HAVE BEGUN TO CLEAR SLOWLY...AND ARE NOW ALLOWING FOR SOME HEATING AND INCREASING INSTABILITY. DO NOT HAVE A GOOD FEEL IN TERMS OF CONVECTION TONIGHT...AS MODELS HAVE BEEN INCONSISTENT AND PRIMARY FORCING REMAINS MOSTLY NORTH OF THE AREA. FOR THESE REASONS...WILL LOWER POPS A BIT. AS MENTIONED...INSTABILITY IS INCREASING WITH LITTLE SURFACE BASED CIN REMAINING ACROSS THE AREA. AN ELONGATED AREA OF LOW PRESSURE EXTENDS FROM WESTERN SD TO WESTERN KS...AND COULD BE THE FOCUS FOR ISOLATED STORM DEVELOPMENT THOUGH THE EVENING. A WARM FRONT ALSO EXTENDS FROM WEST TO EAST ACROSS NORTHERN NEBRASKA...AND COULD ALSO SERVE AS A FOCUS FOR STORM DEVELOPMENT. YET ANOTHER AREA TO WATCH WILL BE ACROSS NORTHEAST COLORADO THIS EVENING...AS HRRR MODEL CONTINUES TO INDICATE STORMS MOVING NORTHEAST INTO SOUTHWEST NEBRASKA THIS EVENING. SO LOTS OF AREAS TO WATCH...BUT LOW CONFIDENCE ON ANY ONE SCENARIO MATERIALIZING. WILL CONTINUE TO MONITOR. WEAK COOL FRONT WILL SETTLE JUST SOUTHEAST OF THE AREA THURSDAY. OVERALL SHOULD BE A FAIRLY QUITE WEATHER DAY...WITH LIGHT NORTH WINDS AND TEMPERATURES IN THE UPPER 80S AND LOWER 90S. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 354 PM CDT WED AUG 20 2014 MAIN FOCUS WILL BE THE STORM SYSTEM MOVING IN THIS WEEKEND WITH THUNDERSTORM CHANCES THURSDAY THROUGH SUNDAY. LOWERED PRECIPITATION CHANCES ACROSS THE SOUTHERN PART OF THE FORECAST AREA AS THE LATEST MODELS ARE TRENDING DRIER DUE TO LACK OF MOISTURE. KEPT THE POPS ACROSS THE NORTHWEST AS MODELS SEEM TO FAVOR STRONGER FORCING AND BETTER MOISTURE AS AN UPPER LEVEL SHORT WAVE TROF PUSHES ACROSS THE AREA. HELD OFF HIGHER PRECIPITATION CHANCES ACROSS THE SOUTHWEST UNTIL FRIDAY AFTERNOON AND EVENING AS CONFIDENCE IS GREATER IN THUNDERSTORM DEVELOPMENT AFTER 18Z. SYSTEM CURRENTLY ACROSS THE SOUTHWESTERN U.S. WILL CONTINUE TO ADVECT NORTHEASTWARD AND WILL COMBINE WITH THE NORTHERN SYSTEM CURRENTLY ACROSS THE GULF OF ALASKA. THE SOUTHWEST SYSTEM WILL TRANSPORT MOISTURE AND VORTICITY ACROSS THE FORECAST AREA FRIDAY AFTERNOON. BY 00Z SATURDAY PRECIPITABLE WATER INCREASES TO 150 PERCENT. SATURDAY NIGHT INTO SUNDAY...AN UPPER LEVEL SHORT WAVE TROF WILL PUSH ACROSS THE FORECAST AREA PUSHING THE RIDGE EASTWARD BRINGING COLDER TEMPERATURES WITH IT. HIGHS ON SUNDAY WILL BE AROUND 10 DEGREES COOLER THAN SATURDAY. COOLER TEMPERATURES WILL CONTINUE THROUGH WED WHEN NEXT TROF IS SET TO PUSH THROUGH THE AREA. THIS SYSTEM WILL BRING STRONG LIFT AS MODELS SUGGEST AN INCREASE IN OMEGA VALUES AND AN ABUNDANT AMOUNT OF MOISTURE WITH DEWPOINTS IN THE 60S CREATING A FAVORABLE THUNDERSTORM DEVELOPMENT TO BE IN PLACE THE NEXT SEVERAL DAYS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1128 PM CDT WED AUG 20 2014 INDICATIONS FROM THE HRRR AND NAM MODELS SUGGEST THE ONGOING CONVECTION COULD LAST SEVERAL MORE HOURS AS IT SHIFTS SLOWLY EAST OVERNIGHT EXITING BY 12Z. VFR IS EXPECTED ALL AREAS THEREAFTER. STRONG WINDS ALOFT AND VERY UNSTABLE AIR LATE THURSDAY AFTERNOON AND EVENING WOULD LIKELY CAUSE TSTM DEVELOPMENT ONCE AGAIN EXCEPT THE MODELS SUGGEST LITTLE IN THE WAY OF AN UPPER LEVEL DISTURBANCE. SO POPS ARE ISOLATED LATE THURSDAY IN THE WEST AND ALONG OR EAST OF HIGHWAY 83. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...TAYLOR LONG TERM...GOMEZ AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
153 PM EDT THU AUG 21 2014 .SYNOPSIS... THE POTENT UPPER LEVEL STORM SYSTEM CONTINUES TO SIT OVER THE REGION. THIS SYSTEM WILL SUPPORT THE CHANCE FOR ADDITIONAL SHOWERS AND THUNDERSTORMS TODAY AND TONIGHT OVER NEW YORK AND PENNSYLVANIA. THE UNSETTLED WEATHER PATTERN WILL SLOWLY IMPROVE BY SATURDAY AS HIGH PRESSURE RETURNS TO THE REGION. && .NEAR TERM /THROUGH TONIGHT/... 1050 AM UPDATE... H5 LOW IS SPINNING OVR GEORGIAN BAY AT THIS TIME. S/WV IS MVG THRU WRN NY AND HAS SPARKED OFF COMPLEX OF TSTMS ACRS THE FINGER LKS AND NOW MVG INTO THE MOHAWK VLY. THESE STORMS HV DVLPD IN 500 MLCAPE AREA AND ARE MVG THUS ONLY GETTING 0.75-1 INCH PER HR AMNTS OUT OF THE HEAVIEST CELLS. EXPECT THIS WL LIKELY BE THE CASE THRU THE DAY AS STORMS DVLP THIS AFTN. THE BULK OF CNY AND ALL OF NEPA ARE NOW IN SEE TEXT FOR SVR STORMS THIS AFTN. 0-6KM BULK SHEAR VALUES INCRS ACRS ZONES FM THE SRN TIER AND POINTS SOUTH TO BTWN 25-30KTS. WITH SOME BREAKS IN CLDS ACRS FINGER LKS AS OF 14Z, INSTABILITIES WL BE ON THE INCRS THIS AFTN. SFC LOW IS SITTING UP ACRS SRN ONTARIO WITH AN ILL- DEFINED WMFNT EXTENDING SOUTH THRU CNTRL NY. LATEST HRRR IS NOW SUGGESTING AREA OF STORMS MVG ACRS NRN ZONES WL BE PULLING INTO ERN ZONES AND OUT OF CWA BY 20Z AS S/WV MVS OFF TO THE EAST. HWVR, ATMOS WL RMN UNSTABLE THRU MOST OF THE DAY TDA AND WITH ANY BNDRYS LURKING WL LKLY SEE DVLPMNT, THO NOT ENUF TO WARRANT LKLY POPS AND WL REDUCE POPS DOWN TO HICHC AT BEST. NO OTHER CHGS NEEDED TO GRIDS. WL CONTINUE THE MENTION OF LOCALLY HVY RAINFALL IN HWO WITH PW VALUES 1-2 SD ABV NORMAL. PREV DISCO BLO... 650 AM EDT UPDATE... MOSTLY CLOUDY SKIES ARE PRESENT THIS MORNING ACROSS PORTIONS OF CENTRAL NY AND NORTHEAST PA. PATCHY FOG HAVE DEVELOP ALONG THE VALLEYS. EXPECT FOG TO LIFT WITHIN THE NEXT COUPLE OF HOURS. SHOWERS HAVE ALSO DEVELOPED ACROSS WESTERN NY AND PA. EXPECT THESE TO DRIFT TO THE EAST AROUND 15-20 MPH. MADE MINOR ADJUSTMENTS TO THE PREVIOUS FORECAST. FOR MORE INFORMATION ON TODAY`S EVENT... PLEASE READ DISCUSSION BELOW. PREVIOUS FORECAST... 430 AM EDT UPDATE... SHOWERS THIS MORNING HAVE PRETTY MUCH TAPERED OFF AND JUST AN ISOLATED LIGHTNING STRIKE HERE ARE STILL GOING. PATCHY VALLEY FOG HAVE ALSO DEVELOPED THIS MORNING AND EXPECT THIS TO MIX OUT SHORTLY AFTER SUNRISE. THE UPPR LEVEL LOW LOCATED OVER THE CENTRAL GREAT LAKES REGION THAT HAVE BROUGHT US SHOWERS YESTERDAY WILL SLIGHTLY WEAKEN TODAY AND DRIFT SLOWLY TOWARDS NY. AS THIS LOW DRIFTS TO THE SOUTH IT WILL EJECT A VORTICITY MAXIMA ACROSS PORTIONS OF CENTRAL NY AND NORTHEAST PA. THIS LOOKS LIKE IT WILL TRIGGER SHOWERS AND THUNDERSTORMS ACROSS THE ARE LATE THIS MORNING/AFTERNOON. ACTIVITY THAT DOES DEVELOPS TODAY WILL HAVE MORE INSTABILITY TO WORK WITH THAN YESTERDAY. GUIDANCE IS INDICATING SBCAPE VALUES AROUND 2500 J/KG... BELIEVE THIS MAY BE A LITTLE HIGH BUT VALUES AROUND 1000 J/KG AREN`T TOO UNREASONABLE. 0-6KM BULK SHEAR VALUES ARE EXPECTED TO BE AROUND 20 KNOTS OVER CENTRAL NY AND 30 OVER NORTHEAST PA. A FEW STRONG STORMS MAY DEVELOP TOMORROW... AND ARE EXPECTED TO BE MAINLY OVER NE PA WHERE THE SHEAR IS A LITTLE STRONGER. WITH THE MENTIONED STATEMENTS ABOVE... EXPECT TO SEE MORE CONVECTION OVERALL TODAY THAN PREVIOUS DAYS. THE BEST MID LVL SUPPORT DURING THE TIME FRAME FOR LATE MORNING/AFTERNOON IS EXPECTED TO BE I-81 AND EAST. PWAT VALUES TODAY ARE ALSO EXPECTED TO BE AROUND 1.4 INCHES GIVE OR TAKE. WITH THAT BEING SAID WE COULD SEE SOME LOCALIZED HEAVY RAINFALL RATES TODAY WITH THE CONVECTION. TONIGHT THE UPPER LVL TROUGH WILL CONTINUE TO SHIFT EAST. SHOWERS MAY LINGER THROUGH THE NIGHT AS WE MAY REMAIN UNDER CYCLONIC FLOW TILL LATE IN THE NIGHT. THE TROUGH AXIS IS EXPECTED TO BE LOCATED OVER CENTRAL NY BY LATE THURSDAY NIGHT/FRIDAY MORNING. DEPENDING ON HOW QUICKLY THE AXIS MOVES EAST WILL DEPEND ON HOW LONG SHOWERS MAY LINGER. TEMPS ARE EXPECTED TO RISE INTO THE 70S AND ISOLATED SPOTS IN THE 80S THIS AFTERNOON AS 850MB TEMPS REMAIN NEAR 14 DECREES CELSIUS. TEMPS TONIGHT ARE EXPECTED TO REMAIN IN THE 60S AS DENSE CLOUD COVERAGE WILL INHIBIT STRONG COOLING. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... 430 AM EDT UPDATE... BY FRIDAY THE UPPR LVL TROUGH WILL BE EAST OF THE AREA AND THE LARGE RIDGE CURRENTLY CENTERED OVER THE SOUTHERN CONUS WILL MOVE EAST AND BECOME SLIGHTLY AMPLIFIED OVER THE MID-WEST. THIS WILL RESULT IN OUR PATTERN ALOFT TRANSITIONING TO A NORTHWESTERLY FLOW. WEAK SPURTS OF ENERGY WILL SLIDE SOUTH INTO OUR AREA ON FRIDAY AND DUE TO THE COMBINATIONS OF LINGERING LOW LVL MOISTURE... WEAK WAVES... AND HEATING FROM THE SUN... SHOWERS AND THUNDERSTORMS MAY DEVELOP ACROSS THE AREA. LATE FRIDAY NIGHT/SATURDAY MORNING WEAK VORTICITY MAXES WILL TRAVEL ALONG THE OUTER EDGE OF THE RIDGE ALOFT AND MAY GENERATE SOME SHOWERS OVER THE WESTERN CWA. BUT... BY SATURDAY AFTERNOON THE UPPR RIDGE WILL BE FURTHER EAST AND SUBSIDENCE WILL START TO TAKE CONTROL OF THE AREA. THIS WILL CREATE AN ENVIRONMENT THAT WILL EVENTUALLY INHIBIT CONVECTIVE DEVELOPMENT. THUS... BY SATURDAY EVENING THE CHANCE FOR SHOWERS WILL BE GONE. TEMPERATURES DURING THIS TIME FRAME WILL RISE INTO THE 70S EACH AFTERNOON AND FALL INTO THE LOW TO MID 50S EACH MORNING. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... 3 AM UPDATE...MEDIUM RANGE MODELS INDICATE A STRONG UPPER LEVEL RIDGE WILL EXTEND FROM THE GULF STATES NORTH INTO THE LOCAL AREA. THIS COMBINED WITH SFC HIGH PRES ALONG THE NEW ENGLAND COAST WILL PROVIDE A PLEASANT STRETCH OF DRY WEATHER WITH TEMPS RUNNING A FEW DEGREES ABOVE SEASONAL NORMALS. BY LATE WEDNESDAY INTO WEDNESDAY NIGHT AN UPPER LEVEL TROF AND ASSOCIATED SFC FRONT MAY BRING THE AREA SOME SHOWERS. 245 PM UPDATE... WPC GUIDANCE LOOKS FINE FOR THE EXTENDED FORECAST WITH DRY WEATHER EXPECTED. A LARGE RIDGE OF HIGH PRESSURE ALOFT, WITH 588 DM HEIGHTS WILL SPREAD INTO THE LOWER GREAT LAKES. SUNDAY THROUGH EARLY NEXT WEEK WE WILL SEE THE IMPACTS OF THIS RIDGE WITH VERY QUIET WEATHER. WITH A NORTHERLY TO NORTHEAST FLOW ALOFT AND NEAR THE SURFACE IT WILL BE COMFORTABLE WITH HIGHS NEAR 80 AND COMFORTABLE NIGHTS. FARTHER DOWN THE ROAD AS THE RIDGE MOVES EAST, OUR FLOW ALOFT WILL BECOME MORE SOUTHWESTERLY. EVENTUALLY THIS SHOULD TRANSLATE INTO MUCH, MUCH WARMER AIR BY THE MIDDLE OF NEXT WEEK. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... 18Z UPDATE... AN UPPER LEVEL LOW IS MOVING THROUGH THE EASTERN GREAT LAKES THIS AFTERNOON. A DISTURBANCE ASSOCIATED WITH THE UPPER LOW...AND DAYTIME HEATING...WILL GENERATE SCATTERED SHOWERS AND THUNDERSTORMS. WHILE MUCH OF THE TIME WILL BE VFR...MOST TERMINALS SHOULD BE IMPACTED AT SOME POINT THIS AFTERNOON TO EARLY EVENING...AND TIMING OF TSRA TEMPO GROUPS IN TAFS HONES INTO MOST LIKELY PERIOD AS BEST AS POSSIBLE /DEFINITELY SUBJECT TO AMENDING AS THINGS EVOLVE/. SYR-RME MAY GET MORE CONVECTION...BUT EARLIER CONVECTION FORCED STABILIZING BOUNDARY TO THE SOUTH AND THUS ACTUAL CB IS LESS CERTAIN COMPARED TO THE REMAINDER OF THE TERMINALS. MOISTURE FROM RAINFALL...AND VERY WEAK FLOW/LACK OF MIXING TONIGHT...WILL LEAD TO MVFR TO IFR DEVELOPMENT OVERNIGHT...AND LIKELY WORSE THAN THAT FOR KELM WHERE FOG WILL SHOULD TURN DENSE. AT LEAST MVFR FOR MUCH OF FRIDAY MORNING WITH SOME GRADUAL IMPROVEMENT BY MIDDAY...YET ALSO NEW SCATTERED SHRA- TSRA POSSIBLE. VARIABLE OR LIGHT SW WIND THIS AFTERNOON...BECOMING LIGHT- VARIABLE TO CALM TONIGHT. LIGHT SE TO S FRIDAY. OUTLOOK... FRI THROUGH FRI NGT...BRIEF RESTRICTIONS POSSIBLE IN SCT SHRA/TSRA FRI AFTERNOON...THEN IFR FOG/STRATUS DEVELOPMENT POSSIBLE FRIDAY NIGHT...ESPECIALLY KELM. SAT THROUGH TUE...VFR EXCEPT RESTRICTIONS POSSIBLE IN EARLY MORNING FOG...MAINLY KELM. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...KAH NEAR TERM...KAH/PVN SHORT TERM...KAH LONG TERM...HEDEN/RRM AVIATION...MDP
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1053 AM EDT THU AUG 21 2014 .SYNOPSIS... THE POTENT UPPR LEVEL STORM SYSTEM CONTINUES TO SIT OVER THE REGION. THIS SYSTEM WILL SUPPORT THE CHANCE FOR ADDITIONAL SHOWERS AND THUNDERSTORMS TODAY AND TONIGHT OVER NEW YORK AND PENNSYLVANIA. THE UNSETTLED WEATHER PATTERN WILL SLOWLY IMPROVE BY SATURDAY AS HIGH PRESSURE RETURNS TO THE REGION. && .NEAR TERM /THROUGH TONIGHT/... 1050 AM UPDATE... H5 LOW IS SPINNING OVR GEORGIAN BAY AT THIS TIME. S/WV IS MVG THRU WRN NY AND HAS SPARKED OFF COMPLEX OF TSTMS ACRS THE FINGER LKS AND NOW MVG INTO THE MOHAWK VLY. THESE STORMS HV DVLPD IN 500 MLCAPE AREA AND ARE MVG THUS ONLY GETTING 0.75-1 INCH PER HR AMNTS OUT OF THE HEAVIEST CELLS. EXPECT THIS WL LIKELY BE THE CASE THRU THE DAY AS STORMS DVLP THIS AFTN. THE BULK OF CNY AND ALL OF NEPA ARE NOW IN SEE TEXT FOR SVR STORMS THIS AFTN. 0-6KM BULK SHEAR VALUES INCRS ACRS ZONES FM THE SRN TIER AND POINTS SOUTH TO BTWN 25-30KTS. WITH SOME BREAKS IN CLDS ACRS FINGER LKS AS OF 14Z, INSTABILITIES WL BE ON THE INCRS THIS AFTN. SFC LOW IS SITTING UP ACRS SRN ONTARIO WITH AN ILL- DEFINED WMFNT EXTENDING SOUTH THRU CNTRL NY. LATEST HRRR IS NOW SUGGESTING AREA OF STORMS MVG ACRS NRN ZONES WL BE PULLING INTO ERN ZONES AND OUT OF CWA BY 20Z AS S/WV MVS OFF TO THE EAST. HWVR, ATMOS WL RMN UNSTABLE THRU MOST OF THE DAY TDA AND WITH ANY BNDRYS LURKING WL LKLY SEE DVLPMNT, THO NOT ENUF TO WARRANT LKLY POPS AND WL REDUCE POPS DOWN TO HICHC AT BEST. NO OTHER CHGS NEEDED TO GRIDS. WL CONTINUE THE MENTION OF LOCALLY HVY RAINFALL IN HWO WITH PW VALUES 1-2 SD ABV NORMAL. PREV DISCO BLO... 650 AM EDT UPDATE... MOSTLY CLOUDY SKIES ARE PRESENT THIS MORNING ACROSS PORTIONS OF CENTRAL NY AND NORTHEAST PA. PATCHY FOG HAVE DEVELOP ALONG THE VALLEYS. EXPECT FOG TO LIFT WITHIN THE NEXT COUPLE OF HOURS. SHOWERS HAVE ALSO DEVELOPED ACROSS WESTERN NY AND PA. EXPECT THESE TO DRIFT TO THE EAST AROUND 15-20 MPH. MADE MINOR ADJUSTMENTS TO THE PREVIOUS FORECAST. FOR MORE INFORMATION ON TODAY`S EVENT... PLEASE READ DISCUSSION BELOW. PREVIOUS FORECAST... 430 AM EDT UPDATE... SHOWERS THIS MORNING HAVE PRETTY MUCH TAPERED OFF AND JUST AN ISOLATED LIGHTNING STRIKE HERE ARE STILL GOING. PATCHY VALLEY FOG HAVE ALSO DEVELOPED THIS MORNING AND EXPECT THIS TO MIX OUT SHORTLY AFTER SUNRISE. THE UPPR LEVEL LOW LOCATED OVER THE CENTRAL GREAT LAKES REGION THAT HAVE BROUGHT US SHOWERS YESTERDAY WILL SLIGHTLY WEAKEN TODAY AND DRIFT SLOWLY TOWARDS NY. AS THIS LOW DRIFTS TO THE SOUTH IT WILL EJECT A VORTICITY MAXIMA ACROSS PORTIONS OF CENTRAL NY AND NORTHEAST PA. THIS LOOKS LIKE IT WILL TRIGGER SHOWERS AND THUNDERSTORMS ACROSS THE ARE LATE THIS MORNING/AFTERNOON. ACTIVITY THAT DOES DEVELOPS TODAY WILL HAVE MORE INSTABILITY TO WORK WITH THAN YESTERDAY. GUIDANCE IS INDICATING SBCAPE VALUES AROUND 2500 J/KG... BELIEVE THIS MAY BE A LITTLE HIGH BUT VALUES AROUND 1000 J/KG AREN`T TOO UNREASONABLE. 0-6KM BULK SHEAR VALUES ARE EXPECTED TO BE AROUND 20 KNOTS OVER CENTRAL NY AND 30 OVER NORTHEAST PA. A FEW STRONG STORMS MAY DEVELOP TOMORROW... AND ARE EXPECTED TO BE MAINLY OVER NE PA WHERE THE SHEAR IS A LITTLE STRONGER. WITH THE MENTIONED STATEMENTS ABOVE... EXPECT TO SEE MORE CONVECTION OVERALL TODAY THAN PREVIOUS DAYS. THE BEST MID LVL SUPPORT DURING THE TIME FRAME FOR LATE MORNING/AFTERNOON IS EXPECTED TO BE I-81 AND EAST. PWAT VALUES TODAY ARE ALSO EXPECTED TO BE AROUND 1.4 INCHES GIVE OR TAKE. WITH THAT BEING SAID WE COULD SEE SOME LOCALIZED HEAVY RAINFALL RATES TODAY WITH THE CONVECTION. TONIGHT THE UPPER LVL TROUGH WILL CONTINUE TO SHIFT EAST. SHOWERS MAY LINGER THROUGH THE NIGHT AS WE MAY REMAIN UNDER CYCLONIC FLOW TILL LATE IN THE NIGHT. THE TROUGH AXIS IS EXPECTED TO BE LOCATED OVER CENTRAL NY BY LATE THURSDAY NIGHT/FRIDAY MORNING. DEPENDING ON HOW QUICKLY THE AXIS MOVES EAST WILL DEPEND ON HOW LONG SHOWERS MAY LINGER. TEMPS ARE EXPECTED TO RISE INTO THE 70S AND ISOLATED SPOTS IN THE 80S THIS AFTERNOON AS 850MB TEMPS REMAIN NEAR 14 DECREES CELSIUS. TEMPS TONIGHT ARE EXPECTED TO REMAIN IN THE 60S AS DENSE CLOUD COVERAGE WILL INHIBIT STRONG COOLING. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... 430 AM EDT UPDATE... BY FRIDAY THE UPPR LVL TROUGH WILL BE EAST OF THE AREA AND THE LARGE RIDGE CURRENTLY CENTERED OVER THE SOUTHERN CONUS WILL MOVE EAST AND BECOME SLIGHTLY AMPLIFIED OVER THE MID-WEST. THIS WILL RESULT IN OUR PATTERN ALOFT TRANSITIONING TO A NORTHWESTERLY FLOW. WEAK SPURTS OF ENERGY WILL SLIDE SOUTH INTO OUR AREA ON FRIDAY AND DUE TO THE COMBINATIONS OF LINGERING LOW LVL MOISTURE... WEAK WAVES... AND HEATING FROM THE SUN... SHOWERS AND THUNDERSTORMS MAY DEVELOP ACROSS THE AREA. LATE FRIDAY NIGHT/SATURDAY MORNING WEAK VORTICITY MAXES WILL TRAVEL ALONG THE OUTER EDGE OF THE RIDGE ALOFT AND MAY GENERATE SOME SHOWERS OVER THE WESTERN CWA. BUT... BY SATURDAY AFTERNOON THE UPPR RIDGE WILL BE FURTHER EAST AND SUBSIDENCE WILL START TO TAKE CONTROL OF THE AREA. THIS WILL CREATE AN ENVIRONMENT THAT WILL EVENTUALLY INHIBIT CONVECTIVE DEVELOPMENT. THUS... BY SATURDAY EVENING THE CHANCE FOR SHOWERS WILL BE GONE. TEMPERATURES DURING THIS TIME FRAME WILL RISE INTO THE 70S EACH AFTERNOON AND FALL INTO THE LOW TO MID 50S EACH MORNING. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... 3 AM UPDATE...MEDIUM RANGE MODELS INDICATE A STRONG UPPER LEVEL RIDGE WILL EXTEND FROM THE GULF STATES NORTH INTO THE LOCAL AREA. THIS COMBINED WITH SFC HIGH PRES ALONG THE NEW ENGLAND COAST WILL PROVIDE A PLEASANT STRETCH OF DRY WEATHER WITH TEMPS RUNNING A FEW DEGREES ABOVE SEASONAL NORMALS. BY LATE WEDNESDAY INTO WEDNESDAY NIGHT AN UPPER LEVEL TROF AND ASSOCIATED SFC FRONT MAY BRING THE AREA SOME SHOWERS. 245 PM UPDATE... WPC GUIDANCE LOOKS FINE FOR THE EXTENDED FORECAST WITH DRY WEATHER EXPECTED. A LARGE RIDGE OF HIGH PRESSURE ALOFT, WITH 588 DM HEIGHTS WILL SPREAD INTO THE LOWER GREAT LAKES. SUNDAY THROUGH EARLY NEXT WEEK WE WILL SEE THE IMPACTS OF THIS RIDGE WITH VERY QUIET WEATHER. WITH A NORTHERLY TO NORTHEAST FLOW ALOFT AND NEAR THE SURFACE IT WILL BE COMFORTABLE WITH HIGHS NEAR 80 AND COMFORTABLE NIGHTS. FARTHER DOWN THE ROAD AS THE RIDGE MOVES EAST, OUR FLOW ALOFT WILL BECOME MORE SOUTHWESTERLY. EVENTUALLY THIS SHOULD TRANSLATE INTO MUCH, MUCH WARMER AIR BY THE MIDDLE OF NEXT WEEK. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... MOST TERMINALS ARE VFR EARLY THIS MORNING WITH THE EXCEPTION OF KELM WHERE CONDITIONS NEAR AIRPORT MINS WILL CONTINUE UNTIL 14Z AND KBGM WHERE LOW MVFR CIGS WILL PERSIST UNTIL 14Z. BY MID MORNING CONDITIONS WILL REMAIN VFR UNTIL WIDESPREAD CONVECTION DEVELOPS THIS AFTERNOON IN RESPONSE TO A MID LEVEL SHORT WAVE ROTATING AROUND THE UPPER LEVEL LOW OVER THE EASTERN LAKES. SHOWERS AND EMBEDDED THUNDERSTORMS ARE LIKELY THIS AFTERNOON INTO THE EARLY EVENING. FOR THE NYS TERMINALS INCLUDED PREVAILING MVFR SHOWERS FROM 18Z-00Z, AT KAVP 21Z-03Z. MVFR RESTRICTIONS WILL CONTINUE THIS EVENING AGAIN DUE TO RAINFALL AND WEAK MIXING. AT KELM DENSE FOG WILL BE LIKELY ONCE AGAIN AFTER 06Z. LIGHT WINDS BECOMING SOUTHWEST AROUND 5 KNOTS THIS MORNING THEN LIGHT AGAIN TONIGHT. OUTLOOK... FRIDAY TO FRI NGT...MVFR RESTRICTIONS POSSIBLE IN AFTN SHRA/TSRA. FRI NGT...IFR FOG AND STRATUS POSSIBLE. SAT-MON...VFR EXCEPT SOME IFR POSSIBLE IN EARLY FOG AT KELM. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...KAH NEAR TERM...KAH/PVN SHORT TERM...KAH LONG TERM...HEDEN/RRM AVIATION...RRM
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1030 PM EDT FRI AUG 22 2014 .SYNOPSIS... A COLD FRONT WILL SLIP SOUTHWARD INTO THE AREA SATURDAY. THIS FRONT WILL BRING A GOOD CHANCE FOR SHOWERS AND THUNDERSTORMS SATURDAY.. .BEFORE MUCH COOLER AND DRIER AIR FILTERS INTO THE REGION FOR SUNDAY. HIGH PRESSURE EXPANDING SOUTH FROM NEW ENGLAND WILL BRING COOL AND DRY WEATHER FOR THE FIRST HALF OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 1030 PM FRIDAY...ALTHOUGH IT AFFECTED ONLY A SMALL PORTION OF OUR FORECAST AREA THIS EVENING`S STORMS WERE IMPRESSIVE. WIND GUSTS WERE MEASURED AS HIGH AS 47 MPH AT WRIGHTSVILLE BEACH...42 MPH AT THE WILMINGTON STATE PORT...AND 39 MPH AT THE WILMINGTON AIRPORT. DUAL-POL RADAR PRECIP ESTIMATIONS APPEAR TO BE RUNNING WITHIN WITHIN 5-10% OF ACTUAL GAUGE TOTALS WITH INDICATE 0.5 TO 2.5 INCH TOTALS ARE WIDESPREAD ACROSS NEW HANOVER AND EASTERN BRUNSWICK COUNTIES. NOW THAT THIS WAVE OF STORMS IS OFFSHORE...ATTENTION TURNS TO THE NEXT UPPER DISTURBANCE CURRENTLY MOVING SOUTHEAST ACROSS THE NC/VA BORDER. THE LAST FEW HRRR RUNS STILL TRY TO CRANK OUT SCATTERED CONVECTIVE SHOWERS AND T-STORMS WITH THIS FEATURE AS IT DIPS INTO THE COASTAL PLAIN VERY LATE TONIGHT. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... A HOT AIRMASS COVERS THE CAROLINAS THIS EVENING. 850 MB TEMPS AROUND +20C USUALLY EQUATES TO UPPER 90S INLAND FROM THE COAST AND TODAY`S HOT TEMPERATURES OF 97 IN FLORENCE AND LUMBERTON WERE EXPECTED. AN UPPER LEVEL RIDGE CENTERED OVER MISSISSIPPI IS PRODUCING A NORTHWEST UPPER WIND OVER THE CAROLINAS. A SERIES OF UPPER LEVEL DISTURBANCES EMBEDDED WITHIN IN THE 20-25 KT 700-500 MB FLOW ARE PRODUCING WAVES OF SHOWERS AND THUNDERSTORMS. ONE SUCH WAVE IS APPROACHING WILMINGTON FROM THE NORTH NOW AND SHOULD BE OFF THE COAST SOUTH OF CAPE FEAR BY LATE THIS EVENING. A SECOND DISTURBANCE NOW IN SOUTHWESTERN VIRGINIA AND EASTERN KENTUCKY WILL TAKE A MORE WESTWARD TRACK...REACHING THE SC PEE DEE AND INTERSTATE 95 CORRIDOR LATE TONIGHT. THIS IS ALSO WHEN A SYNOPTIC COLD FRONT WILL BEGIN TO EASE SOUTHWARD THROUGH SOUTHEASTERN NORTH CAROLINA...REACHING NORTHEASTERN SOUTH CAROLINA BY DAYBREAK SATURDAY. THUNDERSTORMS SHOULD CONTINUE TO BUILD SOUTHWARD INTO WILMINGTON OVER THE NEXT FEW HOURS...AND POPS HAVE BEEN RAISED TO 70 PERCENT FROM BURGAW SOUTH THROUGH WILMINGTON AND WRIGHTSVILLE BEACH. THE AIRMASS IS MODERATELY UNSTABLE (CAPE AROUND 2000 J/KG) AND THERE IS ENOUGH HUMIDITY NEAR THE LCL TO ALLOW SURFACE-BASED PARCELS TO REACH THEIR LFC AND KEEP ON GOING. ACTIVITY WILL BE MUCH MORE SPARSE IN COVERAGE WESTWARD ACROSS THE SOUTH CAROLINA COASTAL PLAIN WHERE ENVIRONMENTAL RELATIVE HUMIDITY NEAR THE LCL IS ONLY 50 TO 60%. OUTSIDE OF AREAS THAT RECEIVE THUNDERSTORMS...TEMPERATURES WILL FALL QUITE SLOWLY THIS EVENING IN THE HOT AIRMASS. NEAR THE COAST DEWPOINTS IN THE MID TO UPPER 70S WILL MAINTAIN HEAT INDICES IN THE AROUND 100 THROUGH 8 PM...AND IN THE 90S UP UNTIL ALMOST MIDNIGHT. LOWS SHOULD ONLY FALL INTO MID 70S FOR MOST ARES WITH SOME UPPER 70S NEAR THE BEACHES. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... AS OF 300 PM FRIDAY...FEATURE OF INTEREST THIS WEEKEND IS A BACK DOOR COLD FRONT WHICH WILL DROP ACROSS THE AREA FROM NE TO SW ON SATURDAY. THIS FRONT WILL BE DRIVEN BY AN AMPLIFYING 5H PATTERN...WITH A STRONG RIDGE GETTING SQUEEZED NORTH ACROSS THE MIDDLE OF THE COUNTRY BETWEEN TROUGHS ON BOTH COASTS. IT IS THIS EASTERN TROUGH DIVING SW THROUGH THE WKND THAT PUSHES THE BACK DOOR FRONT INTO...AND THROUGH...THE CWA SATURDAY. ALTHOUGH THE SURFACE FRONT CROSSES SATURDAY...STRONG CAA LAGS ABOUT 18 HRS BEHIND...AND THUS SATURDAY WILL AGAIN BE A WARM DAY LOCALLY. HOWEVER...INCREASED CLOUDINESS...LOWERED THICKNESSES...AND SHOWERS/STORMS WILL KEEP TEMPS MUCH COOLER THAN THE PAST FEW DAYS...WITH HIGHS RISING TO AROUND 90 IN THE FAR NORTH...MID 90S IN THE SOUTHERN PEE DEE. WHILE FORCING IS NOT STRONG WITH THE FRONT...AND A DIVING UPPER JET WILL ACTUALLY PUT THE REGION BENEATH THE RFQ...AN UNFAVORABLE POSITION FOR UPPER SUPPORT...STILL EXPECT CLIMO POP FOR SCT SHOWERS AND TSTMS THANKS TO PWATS NEAR 2 INCHES AND STRONG SURFACE CONVERGENCE INTO AN UNSTABLE ENVIRONMENT. ALTHOUGH COOL ADVECTION WILL BEGIN OVERNIGHT...LOWS WILL REMAIN ABOVE NORMAL...LOW 70S AREA-WIDE. COOL AND DRY ADVECTION BEGINS IN EARNEST SUNDAY MORNING...AND PWATS DROP TO LESS THAN 1 INCH...LOWEST NORTH...WITH 850MB TEMPS DROPPING 5C THROUGH THE DAY. LOTS OF LATE-AUGUST SUNSHINE WILL SOMEWHAT COUNTERACT STRONG CAA...BUT HIGHS SUNDAY WILL LIKELY BE 5-10 DEGREES COOLER THAN SATURDAY...AND IN FACT ARE EXPECTED TO BE BELOW NORMAL...LOW 80S FAR NORTH TO UPR 80S IN THE SOUTH. A FEW SHOWERS ARE POSSIBLE...ESPECIALLY EARLY IN THE DAY ACROSS THE SC ZONES CLOSER TO THE FRONT...BUT ACTIVITY WILL NOT BE WIDESPREAD OR STRONG. MUCH COOLER MINS SUNDAY NIGHT WITH MID 60S EXPECTED FAR NORTH IN THE DRY COLUMN...UPPER 60S NEAR THE SOUTH SANTEE RIVER AND ON THE BEACHES. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 300 PM FRIDAY...THE EXTENDED FORECAST WILL GENERALLY BE DRY AND SEASONABLE AS A MID LEVEL RIDGE INITIALLY OVER THE MISSISSIPPI VALLEY SHIFTS TO MORE OF A SOUTHERN POSITION BY THE END OF THE PERIOD. AT THE SURFACE...HIGH PRESSURE WILL WEDGE DOWN THE EAST COAST AND EXTEND DOWN INTO GEORGIA FOR MONDAY THROUGH WEDNESDAY. BEYOND THIS...THE FEATURE BREAKS DOWN LEAVING A WEAK PATTERN AT THE SURFACE AND ISOLATED SHOWERS AND THUNDERSTORMS MAKE AN APPEARANCE IN THE FORECAST. THE CHANCES WILL NOT BE GOOD UNTIL FRIDAY WHEN ANOTHER FRONT DROPS INTO THE REGION PROVIDING A BETTER FOCUS. TEMPERATURES WILL BE SLIGHTLY BELOW CLIMATOLOGY MONDAY THROUGH WEDNESDAY WITH THE AXIS OF SURFACE HIGH PRESSURE PROVIDING A COOL NORTHEAST FLOW. THURSDAY AND FRIDAY SEE MODERATING VALUES CLOSER TO OR EVEN A BIT ABOVE NORMAL. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... AS OF 00Z...RADAR IMAGERY SHOWS SOME SHRA/TSRA ASSOCIATED WITH AN UPPER DISTURBANCE MOVING ACROSS OUR NORTHERN ZONES THIS EVENING. WILL MAINTAIN VCSH/VCTS FOR KLBT/KILM EARLY THIS EVENING AS THESE STORMS NEAR THE AREA. IT APPEARS MOST OF THE ACTIVITY AFTER 00Z WILL MISS OUR NORTHERN TERMINALS...THOUGH KILM COULD SEE ANOTHER ROUND OF SHRA TONIGHT BEFORE THE CONVECTION GRADUALLY WEAKENS. EXPECT MAINLY VFR CONDITIONS OVERNIGHT...EXCEPT FOR PERHAPS SOME MVFR VSBYS EARLY SAT MORNING. FCST SOUNDINGS AND GUIDANCE ARE NOT PARTICULARLY KEEN ON FOG...BUT WILL INCLUDE TEMPO MVFR FOR FOG-PRONE KCRE. A COLD FRONT WILL DROP SOUTHWARD OVERNIGHT...NEARING OUR NORTHERN TIER BY 12Z SAT. WINDS WILL SHIFT TO THE NORTH AND THEN NORTHEAST BEHIND THE FRONT...REMAINING BELOW 10 KT. THE NAM HINTS AT SOME POST-FRONTAL MVFR CIGS THRU THE MORNING HOURS...BUT NO SIGN OF IT IN THE GFS/SREF OUTPUT. WILL KEEP CIGS VFR DURING THE DAY SAT. HAVE ADDED VCSH AT ALL SITES AFTER 18Z AS SFC BOUNDARIES COMBINED WITH DEEPENING MOISTURE COULD LEAD TO SCT AFTN CONVECTION. EXTENDED OUTLOOK...EXPECT VFR TO PREVAIL SUN THROUGH WED AS HIGH PRESSURE RIDGES OVER THE EAST COAST IN THE WAKE OF A COLD FRONT. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM FRIDAY...A WAVE OF STRONG THUNDERSTORMS NOW 15-20 MILES SOUTH OF BALD HEAD ISLAND DISRUPTED WIND DIRECTIONS ACROSS THE ENTIRE CAPE FEAR REGION. A NORTH TO NORTHWEST WIND ACROSS THIS AREA NOW SHOULD BACK AROUND TO THE SOUTHWEST AFTER MIDNIGHT. WIND GUSTS WITH THESE STORMS WERE IMPRESSIVE: 47 MPH AT WRIGHTSVILLE BEACH AND 42 MPH AT THE STATE PORT NEAR DOWNTOWN WILMINGTON. A LULL IN THUNDERSTORM ACTIVITY IS EXPECTED BEHIND OUR DEPARTING DISTURBANCE...BUT ADDITIONAL ISOLATED SHOWERS AND T-STORMS COULD DEVELOP LATER TONIGHT AS A SECOND UPPER LEVEL DISTURBANCE APPROACHES FROM THE NORTH. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... A COLD FRONT ACROSS NORTH-CENTRAL NORTH CAROLINA WILL SINK SOUTHWARD OVERNIGHT...REACHING AS FAR SOUTH AS MYRTLE BEACH BY DAYBREAK SATURDAY. UNTIL THEN...SOUTHWEST WINDS 10-15 KNOTS ARE EXPECTED ALONG WITH 2 FOOT SEAS...EVENLY SPLIT BETWEEN A SOUTHEASTERLY SWELL AND A SOUTHWEST WIND CHOP. SCATTERED THUNDERSTORMS AHEAD OF THE FRONT WILL BE MOST NUMEROUS THIS EVENING IN THE CAPE FEAR-AREA WATERS. ANY STORMS WILL BE CAPABLE OF PRODUCING GUSTY OUTFLOW WINDS AND PLENTY OF LIGHTNING. ALTHOUGH COVERAGE WILL DIMINISH OVERNIGHT THE CHANCES OF ADDITIONAL POP-UP STORMS WILL CONTINUE THROUGH DAYBREAK...SHIFTING SOUTHWARD TO THE SOUTH CAROLINA WATERS WITH THE FRONT. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 300 PM FRIDAY...BACK DOOR COLD FRONT WILL DROP ACROSS THE WATERS FROM NE TO SW DURING SATURDAY...CAUSING A WIND SHIFT TO THE N/NE BEHIND THIS BOUNDARY. WIND SHIFT WILL OCCUR FIRST ACROSS THE FAR NORTHERN LEGS OFF THE CAPE FEAR COAST...WITH WINDS BECOMING N THEN NE SATURDAY MORNING...WITH THE WATERS OFF GEORGETOWN COUNTY NOT EXPERIENCING THE WIND SHIFT UNTIL SATURDAY NIGHT. THE GRADIENT REMAINS RELAXED SATURDAY...SO WIND SPEEDS THROUGH THIS FRONTAL PASSAGE WILL BE 5-10 KTS REGARDLESS OF DIRECTION. VERY LATE SATURDAY NIGHT AND ESPECIALLY ON SUNDAY...A NE SURGE OCCURS AND WINDS QUICKLY RISE TO 15-25 KTS ACROSS THE WATERS. SEAS THROUGH THE WKND WILL BE PRIMARILY WIND DRIVEN...RISING FROM 2-3 FT SATURDAY...TO 4-6 FT ON SUNDAY...AND A SMALL CRAFT ADVISORY MAY BE NEEDED. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 300 PM FRIDAY...EXPECT NORTHEAST WINDS THROUGH THE PERIOD COURTESY OF HIGH PRESSURE ALIGNED ALONG THE EASTERN SEABOARD. WIND SPEEDS WILL BE 15-20 KNOTS MONDAY INTO MIDDAY TUESDAY RETREATING FROM THAT POINT ON TO SINGLE DIGITS BY LATER WEDNESDAY. LOWER CONFIDENCE IN SEAS AS THE SPECTRUM IS HIGHLY DEPENDENT ON HOW INVEST AL96 DOES. CURRENTLY THERE IS A FEW SIX FOOTERS ACROSS THE OUTER WATERS OF AMZ252 BUT OTHERWISE THE SEAS ARE 3-5 FEET. IF THE SYSTEM DEVELOPS MORE THAN ANTICIPATED THE SWELL ADDED TO THE SPECTRUM COULD INCREASE THE SIGNIFICANT SEAS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...JDW NEAR TERM...TRA SHORT TERM...JDW LONG TERM...SHK AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
310 PM EDT THU AUG 21 2014 .SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES WILL DIVE SOUTHEAST INTO OUR REGION FROM THE OHIO VALLEY AND MIDWEST. A COLD FRONT LOCATED ACROSS THE MID ATLANTIC ON FRIDAY WILL MOVE SOUTH THROUGH THE AREA OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 310 PM WEDNESDAY... NORTHWEST FLOW CONTINUES ALOFT. THE PIEDMONT TROUGH IS SET UP OVER THE EASTERN PIEDMONT/COASTAL PLAIN...AND AREAS TO THE WEST HAVE SEEN MORE MIXING THAN IN THE EAST WITH MORE WESTERLY FLOW AND DRIER AIR ALOFT. MLCAPE RANGES FROM LESS THAN 1000 J/KG TO AS MUCH AS 2000 J/KG. THE CUMULUS FIELD OVER THE COASTAL PLAIN IN A BIT MORE PRONOUNCED WHERE LOW-LEVEL CONVERGENCE AND INSTABILITY OVERLAP. TO THE NORTHWEST...A SERIES OF UPPER DISTURBANCES ARE MOVING ACROSS KENTUCKY/WEST VIRGINIA. THE MEAN FLOW MAY CAUSE SOME OF THE SCATTERED CONVECTION THAT TRIGGERS FROM THIS DISTURBANCE TO MOVE SOUTHEAST INTO THE NORTHWEST OR NORTHERN PIEDMONT BY THIS EVENING. HOWEVER...THE HRRR CONTINUES TO SHOW VERY LITTLE ACTIVITY THIS AFTERNOON. EFFECTIVE SHEAR WILL INCREASE 25-30KT ACROSS THE NORTH THIS EVENING...SO IF ANY STORMS CAN GET GOING THERE...THEY WILL STAND THE BEST CHANCE OF BEING STRONG TO SEVER WITH THE LOSS OF HEATING...THE CHANCE OF SHOWERS OR STORMS WIL SLOWLY DIMINISH...THOUGH A CHANCE MAY LINGER ACROSS THE NORTH THROUGH MIDNIGHT AS CONVECTION OVER VIRGINIA EVOLVES. LOWS IN THE LOWER 70S. .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 235 PM THURSDAY... FRIDAY WILL BE ANOTHER DAY WITH NORTHWESTERLY FLOW ALOFT...SURFACE TROUGHING IN THE EAST...AND THE POTENTIAL FOR A DISTURBANCE OR TWO TO CROSS THE AREA. THE MAIN DISTURBANCES IN QUESTION ARE LIKELY ASSOCIATED WITH CONVECTION OVER THE UPPER MIDWEST...AND ARE PROGGED TO MOVE SOUTHEAST ACROSS THE AREA LATE FRIDAY AFTERNOON. TIMING OF SUCH A FEATURE IS STILL TOUGH THIS FAR OUT...SO CONFIDENCE IN ITS ADDITIONAL SUPPORT FOR AFTERNOON CONVECTION IS LOW. DEEP MIXING IS EXPECTED AGAIN DURING THE AFTERNOON...WHICH WILL TEMPER INSTABILITY A LITTLE IN THE WEST WHERE DEWPOINTS SHOULD DROP BACK INTO THE MID 60S. THERMAL PROFILES ARE RELATIVELY SIMILAR TO TODAY...SO MLCAPE SHOULD AGAIN RANGE FROM LESS THAN 1000 J/KG IN THE WEST TO OVER 1500 J/KG IN THE EAST. A BELT OF STRONGER WESTERLIES OVER THE CENTRAL APPALACHIANS WILL LIKELY ENHANCE CONVECTION OVER VA...AND SOME OF THIS ACTIVITY MAY DRIFT SOUTH INTO THE NORTHERN PORTIONS OF THE CWA BY FRIDAY EVENING...SO WILL HAVE THE HIGHEST CHANCE POPS ACROSS THE NORTH...WHILE AREAS IN SOUTHERN PIEDMONT MAY STAY DRY. H85 TEMPS ARE FORECAST TO BE ABOVE 20C AGAIN FRIDAY AND WITH DEEP MIXING RESULTS IN MID TO POSSIBLY UPPER 90S. DEWPOINTS ARE FORECAST TO MIX OUT A LITTLE MORE IN THE EAST THAN TODAY...THOUGH ONLY SLIGHTLY...SO HEAT INDEX VALUES SHOULD AGAIN HOLD AROUND 100F IN THE SOUTHEAST. DEPENDING ON HOW MUCH CONVECTION THERE IS TO THE NORTH FRIDAY EVENING...THERE IS THE POTENTIAL FOR A WEAK EFFECTIVE FRONT INTO THE NORTHERN COASTAL PLAIN FRIDAY NIGHT...NECESSITATING POPS THROUGH THE OVERNIGHT HOURS. LOWS IN THE UPPER 60S TO LOWER 70S. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 145 PM THURSDAY... THE LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY WITH A DEEPENING UPPER TROUGH OFF THE EAST COAST...RESULTING IN A NORTHWEST UPPER FLOW REGIME ACROSS CENTRAL NORTH CAROLINA. AT THE SURFACE...A BACKDOOR COLD FRONT WILL MOVE SOUTH THROUGH THE AREA ON SATURDAY. DEEP MOISTURE WILL REMAIN ENTRENCHED OVER THE REGION THROUGH THE FIRST HALF OF THE WEEKEND. AS SUCH...THE BEST CHANCE OF PRECIPITATION WILL BE ON SATURDAY GIVEN THE SURFACE BOUNDARY AND POTENTIAL ADDITIONAL SUPPORT FROM DISTURBANCES ALOFT WITHIN THE NORTHWEST FLOW. THE UPPER TROF AXIS SHIFTS FURTHER OFFSHORE...ALLOWING DRIER AIR TO SURGE SOUTH AT THE MID LEVELS...WITH DEEPER MOISTURE SUPPRESSED SOUTHWEST OF THE AREA SUNDAY THROUGH THE MIDDLE OF NEXT WEEK. THE UPPER RIDGE WILL SHIFT EAST TO FURTHER AID IN DAMPENING CONVECTION AS WELL...SO PRECIP CHANCES WILL BE MINIMAL FROM MONDAY THROUGH THURSDAY. LOW LEVEL THICKNESS VALUES WILL GRADUALLY FALL THROUGH EARLY NEXT WEEK AS THE UPPER TROUGH DEEPENS DOWN THE WESTERN ATLANTIC. IN ADDITION...NORTHEASTERLY SURFACE FLOW WILL PERSIST AS HIGH PRESSURE RIDGES INTO THE AREA FROM THE NORTHEAST. ALL OF THIS WILL RESULT IN BELOW NORMAL TEMPS...WITH MID 80S TO NEAR 90 DEGREES ON SATURDAY FALLING INTO THE UPPER 70S TO LOW/MID 80S SUNDAY THROUGH TUESDAY. TEMPS WILL BEGIN TO MODERATE WEDNESDAY INTO THURSDAY AS THE UPPER RIDGE SHIFTS EAST. OVERNIGHT LOWS THIS WEEKEND WILL BE IN THE UPPER 60S TO LOWER 70S...WITH MID TO UPPER 60S MONDAY MORNING AND FOR THE REMAINDER OF THE WEEK. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 200 PM THURSDAY... VFR CONDITIONS ACROSS CENTRAL NC THIS AFTERNOON WITH A GENERALLY LIGHT WESTERLY WIND. A COUPLE WEAK DISTURBANCES WITHIN THE NORTHWESTERLY FLOW ALOFT WILL CROSS THE APPALACHIANS THIS EVENING...BUT THERE IS RELATIVELY LOW CONFIDENCE IN WHETHER OR NOT ADDITIONAL SHOWERS AND STORMS WILL BE ABLE TO MOVE EAST INTO THE PIEDMONT THIS AFTERNOON. TO THE EAST...WHERE INSTABILITY IS GREATEST...SOME WEAK CONVERGENCE MAY SUPPORT STORMS OVER THE COASTAL PLAIN...MOSTLY FROM KFAY TO KRWI AND EAST. HOWEVER...CONFIDENCE IS TOO LOW FOR MENTION IN THE CURRENT TAF. MOST OF ANY CONVECTION WILL DIE DOWN AFTER SUNSET...THOUGH MODELS SHOW THE POTENTIAL FOR SOME ADDITIONAL STORMS MOVING THROUGH SOUTHERN VA TO TRACK INTO THE NORTHERN COASTAL PLAIN OVERNIGHT. FOG AND STRATUS SHOULD AGAIN BE ISOLATED AND MOSTLY MVFR. OUTLOOK... A BACKDOOR COLD FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...BRINGING A PERIOD OF UNSETTLED WEATHER AND ADVERSE AVIATION CONDITIONS. DRIER WEATHER IS EXPECTED NEXT WEEK. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLS SHORT TERM...BLS LONG TERM...MLM AVIATION...BLS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
235 PM EDT THU AUG 21 2014 .SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES WILL DIVE SOUTHEAST INTO OUR REGION FROM THE OHIO VALLEY AND MIDWEST. A COLD FRONT LOCATED ACROSS THE MID ATLANTIC ON FRIDAY WILL MOVE SOUTH THROUGH THE AREA OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1045 AM WEDNESDAY... NORTHWEST FLOW CONTINUES ALOFT...THOUGH TODAY WITH LESS IN THE WAY OF A DISCERNIBLE FEATURE TO TRIGGER CONVECTION. THE PIEDMONT TROUGH IS SET UP OVER THE EASTERN PIEDMONT/COASTAL PLAIN...AND AREAS TO THE WEST WILL SEE MORE OF A WESTERLY FLOW AND BETTER MIXING. DRY ADIABATIC MIXING RESULTS IN HIGHS IN THE MID 90 MOST AREAS AND DEWPOINTS IN THE LOWER 60S WEST TO NEAR 70 EAST. THE LOWER DEWPOINTS SHOULD LIMIT MLCAPE TO AROUND 1000 J/KG OR LESS AND MAKE IT HARD FOR ANY CONVECTION IN THE MOUNTAINS TO MOVE INTO THE PIEDMONT. HOWEVER...A COUPLE HRRR RUNS HAVE HINTED AT SOME STORMS CONGEALING INTO A SMALL LINE...LIKELY AIDED BY EVAPORATIVE COOLING AND COLD POOL ENHANCEMENT. HOWEVER...THE MOST RECENT HRRR RUN HAS BACKED OFF ON THIS. WILL BE WATCHING SOME WEAK DISTURBANCES OVER EASTERN KY/TN TO SEE IF ANYTHING TRIGGERS....BUT FOR NOW POPS WILL BE LESS THAN 25 PERCENT. HEAT INDICES WILL BE 100-103 ROUGHLY EAST OF US 1. OVERNIGHT LOWS IN THE LOWER 70S. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 235 PM THURSDAY... FRIDAY WILL BE ANOTHER DAY WITH NORTHWESTERLY FLOW ALOFT...SURFACE TROUGHING IN THE EAST...AND THE POTENTIAL FOR A DISTURBANCE OR TWO TO CROSS THE AREA. THE MAIN DISTURBANCES IN QUESTION ARE LIKELY ASSOCIATED WITH CONVECTION OVER THE UPPER MIDWEST...AND ARE PROGGED TO MOVE SOUTHEAST ACROSS THE AREA LATE FRIDAY AFTERNOON. TIMING OF SUCH A FEATURE IS STILL TOUGH THIS FAR OUT...SO CONFIDENCE IN ITS ADDITIONAL SUPPORT FOR AFTERNOON CONVECTION IS LOW. DEEP MIXING IS EXPECTED AGAIN DURING THE AFTERNOON...WHICH WILL TEMPER INSTABILITY A LITTLE IN THE WEST WHERE DEWPOINTS SHOULD DROP BACK INTO THE MID 60S. THERMAL PROFILES ARE RELATIVELY SIMILAR TO TODAY...SO MLCAPE SHOULD AGAIN RANGE FROM LESS THAN 1000 J/KG IN THE WEST TO OVER 1500 J/KG IN THE EAST. A BELT OF STRONGER WESTERLIES OVER THE CENTRAL APPALACHIANS WILL LIKELY ENHANCE CONVECTION OVER VA...AND SOME OF THIS ACTIVITY MAY DRIFT SOUTH INTO THE NORTHERN PORTIONS OF THE CWA BY FRIDAY EVENING...SO WILL HAVE THE HIGHEST CHANCE POPS ACROSS THE NORTH...WHILE AREAS IN SOUTHERN PIEDMONT MAY STAY DRY. H85 TEMPS ARE FORECAST TO BE ABOVE 20C AGAIN FRIDAY AND WITH DEEP MIXING RESULTS IN MID TO POSSIBLY UPPER 90S. DEWPOINTS ARE FORECAST TO MIX OUT A LITTLE MORE IN THE EAST THAN TODAY...THOUGH ONLY SLIGHTLY...SO HEAT INDEX VALUES SHOULD AGAIN HOLD AROUND 100F IN THE SOUTHEAST. DEPENDING ON HOW MUCH CONVECTION THERE IS TO THE NORTH FRIDAY EVENING...THERE IS THE POTENTIAL FOR A WEAK EFFECTIVE FRONT INTO THE NORTHERN COASTAL PLAIN FRIDAY NIGHT...NECESSITATING POPS THROUGH THE OVERNIGHT HOURS. LOWS IN THE UPPER 60S TO LOWER 70S. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 145 PM THURSDAY... THE LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY WITH A DEEPENING UPPER TROUGH OFF THE EAST COAST...RESULTING IN A NORTHWEST UPPER FLOW REGIME ACROSS CENTRAL NORTH CAROLINA. AT THE SURFACE...A BACKDOOR COLD FRONT WILL MOVE SOUTH THROUGH THE AREA ON SATURDAY. DEEP MOISTURE WILL REMAIN ENTRENCHED OVER THE REGION THROUGH THE FIRST HALF OF THE WEEKEND. AS SUCH...THE BEST CHANCE OF PRECIPITATION WILL BE ON SATURDAY GIVEN THE SURFACE BOUNDARY AND POTENTIAL ADDITIONAL SUPPORT FROM DISTURBANCES ALOFT WITHIN THE NORTHWEST FLOW. THE UPPER TROF AXIS SHIFTS FURTHER OFFSHORE...ALLOWING DRIER AIR TO SURGE SOUTH AT THE MID LEVELS...WITH DEEPER MOISTURE SUPPRESSED SOUTHWEST OF THE AREA SUNDAY THROUGH THE MIDDLE OF NEXT WEEK. THE UPPER RIDGE WILL SHIFT EAST TO FURTHER AID IN DAMPENING CONVECTION AS WELL...SO PRECIP CHANCES WILL BE MINIMAL FROM MONDAY THROUGH THURSDAY. LOW LEVEL THICKNESS VALUES WILL GRADUALLY FALL THROUGH EARLY NEXT WEEK AS THE UPPER TROUGH DEEPENS DOWN THE WESTERN ATLANTIC. IN ADDITION...NORTHEASTERLY SURFACE FLOW WILL PERSIST AS HIGH PRESSURE RIDGES INTO THE AREA FROM THE NORTHEAST. ALL OF THIS WILL RESULT IN BELOW NORMAL TEMPS...WITH MID 80S TO NEAR 90 DEGREES ON SATURDAY FALLING INTO THE UPPER 70S TO LOW/MID 80S SUNDAY THROUGH TUESDAY. TEMPS WILL BEGIN TO MODERATE WEDNESDAY INTO THURSDAY AS THE UPPER RIDGE SHIFTS EAST. OVERNIGHT LOWS THIS WEEKEND WILL BE IN THE UPPER 60S TO LOWER 70S...WITH MID TO UPPER 60S MONDAY MORNING AND FOR THE REMAINDER OF THE WEEK. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 200 PM THURSDAY... VFR CONDITIONS ACROSS CENTRAL NC THIS AFTERNOON WITH A GENERALLY LIGHT WESTERLY WIND. A COUPLE WEAK DISTURBANCES WITHIN THE NORTHWESTERLY FLOW ALOFT WILL CROSS THE APPALACHIANS THIS EVENING...BUT THERE IS RELATIVELY LOW CONFIDENCE IN WHETHER OR NOT ADDITIONAL SHOWERS AND STORMS WILL BE ABLE TO MOVE EAST INTO THE PIEDMONT THIS AFTERNOON. TO THE EAST...WHERE INSTABILITY IS GREATEST...SOME WEAK CONVERGENCE MAY SUPPORT STORMS OVER THE COASTAL PLAIN...MOSTLY FROM KFAY TO KRWI AND EAST. HOWEVER...CONFIDENCE IS TOO LOW FOR MENTION IN THE CURRENT TAF. MOST OF ANY CONVECTION WILL DIE DOWN AFTER SUNSET...THOUGH MODELS SHOW THE POTENTIAL FOR SOME ADDITIONAL STORMS MOVING THROUGH SOUTHERN VA TO TRACK INTO THE NORTHERN COASTAL PLAIN OVERNIGHT. FOG AND STRATUS SHOULD AGAIN BE ISOLATED AND MOSTLY MVFR. OUTLOOK... A BACKDOOR COLD FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...BRINGING A PERIOD OF UNSETTLED WEATHER AND ADVERSE AVIATION CONDITIONS. DRIER WEATHER IS EXPECTED NEXT WEEK. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...CBL/BLS SHORT TERM...BLS LONG TERM...MLM AVIATION...BLS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
200 PM EDT THU AUG 21 2014 .SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES IN NORTHWEST FLOW ALOFT WILL CROSS THE REGION THROUGH LATE WEEK. A BACK DOOR COLD FRONT WILL MOVE SOUTH OF THE AREA ON SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1045 AM WEDNESDAY... NORTHWEST FLOW CONTINUES ALOFT...THOUGH TODAY WITH LESS IN THE WAY OF A DISCERNIBLE FEATURE TO TRIGGER CONVECTION. THE PIEDMONT TROUGH IS SET UP OVER THE EASTERN PIEDMONT/COASTAL PLAIN...AND AREAS TO THE WEST WILL SEE MORE OF A WESTERLY FLOW AND BETTER MIXING. DRY ADIABATIC MIXING RESULTS IN HIGHS IN THE MID 90 MOST AREAS AND DEWPOINTS IN THE LOWER 60S WEST TO NEAR 70 EAST. THE LOWER DEWPOINTS SHOULD LIMIT MLCAPE TO AROUND 1000 J/KG OR LESS AND MAKE IT HARD FOR ANY CONVECTION IN THE MOUNTAINS TO MOVE INTO THE PIEDMONT. HOWEVER...A COUPLE HRRR RUNS HAVE HINTED AT SOME STORMS CONGEALING INTO A SMALL LINE...LIKELY AIDED BY EVAPORATIVE COOLING AND COLD POOL ENHANCEMENT. HOWEVER...THE MOST RECENT HRRR RUN HAS BACKED OFF ON THIS. WILL BE WATCHING SOME WEAK DISTURBANCES OVER EASTERN KY/TN TO SEE IF ANYTHING TRIGGERS....BUT FOR NOW POPS WILL BE LESS THAN 25 PERCENT. HEAT INDICES WILL BE 100-103 ROUGHLY EAST OF US 1. OVERNIGHT LOWS IN THE LOWER 70S. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 320 AM THURSDAY... UPPER RIDGE OVER THE CENTRAL US CONTINUES TO AMPLIFY AS THE UPPER TROUGH MOVES OFF THE MID-ATLANTIC COAST. WHILE THERE CONTINUES TO BE CONSIDERABLE RUN-TO-RUN VARIABILITY WITH HOW NWP GUIDANCE HANDLE INDIVIDUAL SHORTWAVES EMBEDDED IN THE MEAN TROUGH...THE OVERRIDING THEME OVER THE LAST SEVERAL DAYS HAS BEEN RATHER CONSISTENT IN SHOWING AN INCREASE/UPTICK IN RAIN CHANCES/POPS LATE FRIDAY AND INTO FRIDAY NIGHT IN RESPONSE TO THE BROADER SYNOPTIC SCALE ASCENT MOVING DOWN THE MID-ATLANTIC COAST AND ATTENDANT BACK-DOOR FRONTAL INTO THE AREA. WILL MAINTAIN CURRENT POP CONFIGURATION WITH HIGH CHANCE POPS ACROSS THE NORTH INVOF OF THE BETTER FORCING AND LOW CHANCE POPS SOUTH. A TOUCH COOLER ON FRIDAY AS HEIGHTS LOWER ALOFT COMBINED WITH AN INCREASE IN CLOUD COVER AND RAIN CHANCES. HIGHS IN THE LOWER 90S NORTH TO MID 90S SOUTH. LOWS FRIDAY NIGHT IN THE UPPER 60S TO LOWER 70S. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 145 PM THURSDAY... THE LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY WITH A DEEPENING UPPER TROUGH OFF THE EAST COAST...RESULTING IN A NORTHWEST UPPER FLOW REGIME ACROSS CENTRAL NORTH CAROLINA. AT THE SURFACE...A BACKDOOR COLD FRONT WILL MOVE SOUTH THROUGH THE AREA ON SATURDAY. DEEP MOISTURE WILL REMAIN ENTRENCHED OVER THE REGION THROUGH THE FIRST HALF OF THE WEEKEND. AS SUCH...THE BEST CHANCE OF PRECIPITATION WILL BE ON SATURDAY GIVEN THE SURFACE BOUNDARY AND POTENTIAL ADDITIONAL SUPPORT FROM DISTURBANCES ALOFT WITHIN THE NORTHWEST FLOW. THE UPPER TROF AXIS SHIFTS FURTHER OFFSHORE...ALLOWING DRIER AIR TO SURGE SOUTH AT THE MID LEVELS...WITH DEEPER MOISTURE SUPPRESSED SOUTHWEST OF THE AREA SUNDAY THROUGH THE MIDDLE OF NEXT WEEK. THE UPPER RIDGE WILL SHIFT EAST TO FURTHER AID IN DAMPENING CONVECTION AS WELL...SO PRECIP CHANCES WILL BE MINIMAL FROM MONDAY THROUGH THURSDAY. LOW LEVEL THICKNESS VALUES WILL GRADUALLY FALL THROUGH EARLY NEXT WEEK AS THE UPPER TROUGH DEEPENS DOWN THE WESTERN ATLANTIC. IN ADDITION...NORTHEASTERLY SURFACE FLOW WILL PERSIST AS HIGH PRESSURE RIDGES INTO THE AREA FROM THE NORTHEAST. ALL OF THIS WILL RESULT IN BELOW NORMAL TEMPS...WITH MID 80S TO NEAR 90 DEGREES ON SATURDAY FALLING INTO THE UPPER 70S TO LOW/MID 80S SUNDAY THROUGH TUESDAY. TEMPS WILL BEGIN TO MODERATE WEDNESDAY INTO THURSDAY AS THE UPPER RIDGE SHIFTS EAST. OVERNIGHT LOWS THIS WEEKEND WILL BE IN THE UPPER 60S TO LOWER 70S...WITH MID TO UPPER 60S MONDAY MORNING AND FOR THE REMAINDER OF THE WEEK. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 200 PM THURSDAY... VFR CONDITIONS ACROSS CENTRAL NC THIS AFTERNOON WITH A GENERALLY LIGHT WESTERLY WIND. A COUPLE WEAK DISTURBANCES WITHIN THE NORTHWESTERLY FLOW ALOFT WILL CROSS THE APPALACHIANS THIS EVENING...BUT THERE IS RELATIVELY LOW CONFIDENCE IN WHETHER OR NOT ADDITIONAL SHOWERS AND STORMS WILL BE ABLE TO MOVE EAST INTO THE PIEDMONT THIS AFTERNOON. TO THE EAST...WHERE INSTABILITY IS GREATEST...SOME WEAK CONVERGENCE MAY SUPPORT STORMS OVER THE COASTAL PLAIN...MOSTLY FROM KFAY TO KRWI AND EAST. HOWEVER...CONFIDENCE IS TOO LOW FOR MENTION IN THE CURRENT TAF. MOST OF ANY CONVECTION WILL DIE DOWN AFTER SUNSET...THOUGH MODELS SHOW THE POTENTIAL FOR SOME ADDITIONAL STORMS MOVING THROUGH SOUTHERN VA TO TRACK INTO THE NORTHERN COASTAL PLAIN OVERNIGHT. FOG AND STRATUS SHOULD AGAIN BE ISOLATED AND MOSTLY MVFR. OUTLOOK... A BACKDOOR COLD FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...BRINGING A PERIOD OF UNSETTLED WEATHER AND ADVERSE AVIATION CONDITIONS. DRIER WEATHER IS EXPECTED NEXT WEEK. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PWB NEAR TERM...CBL/BLS SHORT TERM...CBL LONG TERM...MLM AVIATION...BLS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
145 PM EDT THU AUG 21 2014 .SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES IN NORTHWEST FLOW ALOFT WILL CROSS THE REGION THROUGH LATE WEEK. A BACK DOOR COLD FRONT WILL MOVE SOUTH OF THE AREA ON SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1045 AM WEDNESDAY... NORTHWEST FLOW CONTINUES ALOFT...THOUGH TODAY WITH LESS IN THE WAY OF A DISCERNIBLE FEATURE TO TRIGGER CONVECTION. THE PIEDMONT TROUGH IS SET UP OVER THE EASTERN PIEDMONT/COASTAL PLAIN...AND AREAS TO THE WEST WILL SEE MORE OF A WESTERLY FLOW AND BETTER MIXING. DRY ADIABATIC MIXING RESULTS IN HIGHS IN THE MID 90 MOST AREAS AND DEWPOINTS IN THE LOWER 60S WEST TO NEAR 70 EAST. THE LOWER DEWPOINTS SHOULD LIMIT MLCAPE TO AROUND 1000 J/KG OR LESS AND MAKE IT HARD FOR ANY CONVECTION IN THE MOUNTAINS TO MOVE INTO THE PIEDMONT. HOWEVER...A COUPLE HRRR RUNS HAVE HINTED AT SOME STORMS CONGEALING INTO A SMALL LINE...LIKELY AIDED BY EVAPORATIVE COOLING AND COLD POOL ENHANCEMENT. HOWEVER...THE MOST RECENT HRRR RUN HAS BACKED OFF ON THIS. WILL BE WATCHING SOME WEAK DISTURBANCES OVER EASTERN KY/TN TO SEE IF ANYTHING TRIGGERS....BUT FOR NOW POPS WILL BE LESS THAN 25 PERCENT. HEAT INDICES WILL BE 100-103 ROUGHLY EAST OF US 1. OVERNIGHT LOWS IN THE LOWER 70S. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 320 AM THURSDAY... UPPER RIDGE OVER THE CENTRAL US CONTINUES TO AMPLIFY AS THE UPPER TROUGH MOVES OFF THE MID-ATLANTIC COAST. WHILE THERE CONTINUES TO BE CONSIDERABLE RUN-TO-RUN VARIABILITY WITH HOW NWP GUIDANCE HANDLE INDIVIDUAL SHORTWAVES EMBEDDED IN THE MEAN TROUGH...THE OVERRIDING THEME OVER THE LAST SEVERAL DAYS HAS BEEN RATHER CONSISTENT IN SHOWING AN INCREASE/UPTICK IN RAIN CHANCES/POPS LATE FRIDAY AND INTO FRIDAY NIGHT IN RESPONSE TO THE BROADER SYNOPTIC SCALE ASCENT MOVING DOWN THE MID-ATLANTIC COAST AND ATTENDANT BACK-DOOR FRONTAL INTO THE AREA. WILL MAINTAIN CURRENT POP CONFIGURATION WITH HIGH CHANCE POPS ACROSS THE NORTH INVOF OF THE BETTER FORCING AND LOW CHANCE POPS SOUTH. A TOUCH COOLER ON FRIDAY AS HEIGHTS LOWER ALOFT COMBINED WITH AN INCREASE IN CLOUD COVER AND RAIN CHANCES. HIGHS IN THE LOWER 90S NORTH TO MID 90S SOUTH. LOWS FRIDAY NIGHT IN THE UPPER 60S TO LOWER 70S. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 145 PM THURSDAY... THE LONG TERM PERIOD REMAINS CHARACTERIZED BY A BUILDING UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY WITH A DEEPENING UPPER TROUGH OFF THE EAST COAST...RESULTING IN A NORTHWEST UPPER FLOW REGIME ACROSS CENTRAL NORTH CAROLINA. AT THE SURFACE...A BACKDOOR COLD FRONT WILL MOVE SOUTH THROUGH THE AREA ON SATURDAY. DEEP MOISTURE WILL REMAIN ENTRENCHED OVER THE REGION THROUGH THE FIRST HALF OF THE WEEKEND. AS SUCH...THE BEST CHANCE OF PRECIPITATION WILL BE ON SATURDAY GIVEN THE SURFACE BOUNDARY AND POTENTIAL ADDITIONAL SUPPORT FROM DISTURBANCES ALOFT WITHIN THE NORTHWEST FLOW. THE UPPER TROF AXIS SHIFTS FURTHER OFFSHORE...ALLOWING DRIER AIR TO SURGE SOUTH AT THE MID LEVELS...WITH DEEPER MOISTURE SUPPRESSED SOUTHWEST OF THE AREA SUNDAY THROUGH THE MIDDLE OF NEXT WEEK. THE UPPER RIDGE WILL SHIFT EAST TO FURTHER AID IN DAMPENING CONVECTION AS WELL...SO PRECIP CHANCES WILL BE MINIMAL FROM MONDAY THROUGH THURSDAY. LOW LEVEL THICKNESS VALUES WILL GRADUALLY FALL THROUGH EARLY NEXT WEEK AS THE UPPER TROUGH DEEPENS DOWN THE WESTERN ATLANTIC. IN ADDITION...NORTHEASTERLY SURFACE FLOW WILL PERSIST AS HIGH PRESSURE RIDGES INTO THE AREA FROM THE NORTHEAST. ALL OF THIS WILL RESULT IN BELOW NORMAL TEMPS...WITH MID 80S TO NEAR 90 DEGREES ON SATURDAY FALLING INTO THE UPPER 70S TO LOW/MID 80S SUNDAY THROUGH TUESDAY. TEMPS WILL BEGIN TO MODERATE WEDNESDAY INTO THURSDAY AS THE UPPER RIDGE SHIFTS EAST. OVERNIGHT LOWS THIS WEEKEND WILL BE IN THE UPPER 60S TO LOWER 70S...WITH MID TO UPPER 60S MONDAY MORNING AND FOR THE REMAINDER OF THE WEEK. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 715 AM THURSDAY... ANY SUB-VFR CONDITIONS WILL AGAIN LIFT TO VFR BY MID TO LATE MORNING AT THE LATEST... WITH THE PROSPECTS OF VFR CONDITIONS BY 13-15Z AT ALL TAF SITES. ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS WILL BE POSSIBLE AGAIN ON THURSDAY ACROSS ALL OF CENTRAL NC. HOWEVER... THE PROBABILITY AT A GIVEN SITE IS TOO LOW TO INCLUDE IN THE TAFS AT THIS TIME. OUTLOOK... EARLY MORNING STRATUS/FOG...ALONG WITH AFTERNOON SHOWERS AND STORMS WILL BE POSSIBLE EACH DAY THIS WEEK. A BACKDOOR COLD FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...WHICH MAY BRING ANOTHER PERIOD UNSETTLED WEATHER FOR PORTIONS OF THE AREA. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PWB NEAR TERM...CBL/BLS SHORT TERM...CBL LONG TERM...MLM AVIATION...CBL/BLS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1045 AM EDT THU AUG 21 2014 .SYNOPSIS...A SERIES OF UPPER LEVEL DISTURBANCES IN NORTHWEST FLOW ALOFT WILL CROSS THE REGION THROUGH LATE WEEK. A BACK DOOR COLD FRONT IS FORECAST TO SLIP INTO THE AREA OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1045 AM WEDNESDAY... NORTHWEST FLOW CONTINUES ALOFT...THOUGH TODAY WITH LESS IN THE WAY OF A DISCERNIBLE FEATURE TO TRIGGER CONVECTION. THE PIEDMONT TROUGH IS SET UP OVER THE EASTERN PIEDMONT/COASTAL PLAIN...AND AREAS TO THE WEST WILL SEE MORE OF A WESTERLY FLOW AND BETTER MIXING. DRY ADIABATIC MIXING RESULTS IN HIGHS IN THE MID 90 MOST AREAS AND DEWPOINTS IN THE LOWER 60S WEST TO NEAR 70 EAST. THE LOWER DEWPOINTS SHOULD LIMIT MLCAPE TO AROUND 1000 J/KG OR LESS AND MAKE IT HARD FOR ANY CONVECTION IN THE MOUNTAINS TO MOVE INTO THE PIEDMONT. HOWEVER...A COUPLE HRRR RUNS HAVE HINTED AT SOME STORMS CONGEALING INTO A SMALL LINE...LIKELY AIDED BY EVAPORATIVE COOLING AND COLD POOL ENHANCEMENT. HOWEVER...THE MOST RECENT HRRR RUN HAS BACKED OFF ON THIS. WILL BE WATCHING SOME WEAK DISTURBANCES OVER EASTERN KY/TN TO SEE IF ANYTHING TRIGGERS....BUT FOR NOW POPS WILL BE LESS THAN 25 PERCENT. HEAT INDICES WILL BE 100-103 ROUGHLY EAST OF US 1. OVERNIGHT LOWS IN THE LOWER 70S. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 320 AM THURSDAY... UPPER RIDGE OVER THE CENTRAL US CONTINUES TO AMPLIFY AS THE UPPER TROUGH MOVES OFF THE MID-ATLANTIC COAST. WHILE THERE CONTINUES TO BE CONSIDERABLE RUN-TO-RUN VARIABILITY WITH HOW NWP GUIDANCE HANDLE INDIVIDUAL SHORTWAVES EMBEDDED IN THE MEAN TROUGH...THE OVERRIDING THEME OVER THE LAST SEVERAL DAYS HAS BEEN RATHER CONSISTENT IN SHOWING AN INCREASE/UPTICK IN RAIN CHANCES/POPS LATE FRIDAY AND INTO FRIDAY NIGHT IN RESPONSE TO THE BROADER SYNOPTIC SCALE ASCENT MOVING DOWN THE MID-ATLANTIC COAST AND ATTENDANT BACK-DOOR FRONTAL INTO THE AREA. WILL MAINTAIN CURRENT POP CONFIGURATION WITH HIGH CHANCE POPS ACROSS THE NORTH INVOF OF THE BETTER FORCING AND LOW CHANCE POPS SOUTH. A TOUCH COOLER ON FRIDAY AS HEIGHTS LOWER ALOFT COMBINED WITH AN INCREASE IN CLOUD COVER AND RAIN CHANCES. HIGHS IN THE LOWER 90S NORTH TO MID 90S SOUTH. LOWS FRIDAY NIGHT IN THE UPPER 60S TO LOWER 70S. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 300 AM THURSDAY... THE LONG TERM PERIOD WILL BE CHARACTERIZED BY A BUILDING UPPER RIDGE ACROSS THE MISSISSIPPI RIVER VALLEY WITH AN UPPER TROUGH/CLOSED LOW OFF THE NORTHEAST COAST...LEAVING CENTRAL NC UNDER A NORTHWESTERLY UPPER FLOW REGIME. THIS UPPER RIDGE IS PROGGED TO SHIFT EAST TOWARDS THE REGION BY THE MIDDLE OF NEXT WEEK. AS THE SURFACE...A BACKDOOR COLD FRONT WILL BE SLIPPING FURTHER TO OUR SOUTH AND WEST THROUGH THE DAY ON SATURDAY. DEEP MOISTURE WILL REMAIN ENTRENCHED OVER THE REGION THROUGH AT LEAST THE FIRST HALF OF THE WEEKEND AND GIVEN THIS SURFACE BOUNDARY AND ANY DISTURBANCES ALOFT WITHIN THE NORTHWESTERLY FLOW...PRECIP CHANCES WILL BE THE HIGHEST ON SATURDAY. THE DEEP MOISTURE BEGINS TO GET SHUNTED TO OUR SOUTHWEST ON SUNDAY...BUT ESPECIALLY INTO EARLY NEXT WEEK. THIS WILL RESULT IN DECREASING PRECIP CHANCES AND IN FACT HAVE REMOVED MENTION OF PRECIP FROM THE FORECAST BY THE EARLY TO MIDDLE PART OF NEXT WEEK...ESPECIALLY GIVEN THAT THE UPPER RIDGE WILL BUILD TOWARDS THE AREA. LOW LEVEL THICKNESS VALUES WILL GRADUALLY FALL THROUGH EARLY NEXT WEEK AS THE UPPER TROUGH DEEPENS DOWN THE WESTERN ATLANTIC. IN ADDITION...NORTHEASTERLY SURFACE FLOW WILL PERSIST AS HIGH PRESSURE RIDGES INTO THE AREA FROM THE NORTHEAST. ALL OF THIS WILL RESULT IN BELOW NORMAL TEMPS...WITH MID 80S TO NEAR 90 DEGREES ON SATURDAY AND UPPER 70S TO LOW/MID 80S EXPECTED FOR SUNDAY AND EARLY NEXT WEEK. TEMPS WILL BEGIN TO MODERATE TUESDAY AND ESPECIALLY INTO WEDNESDAY AS THE UPPER RIDGE SHIFTS EAST. OVERNIGHT LOWS WILL INITIALLY BE IN THE UPPER 60S TO LOWER 70S...WITH SLIGHTLY COOLER TEMPS FOR THE REMAINDER OF THE PERIOD (MOSTLY MID/UPPER 60S WITH SOME LOWER 60S IN THE COOLER LOCATIONS). && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 715 AM THURSDAY... ANY SUB-VFR CONDITIONS WILL AGAIN LIFT TO VFR BY MID TO LATE MORNING AT THE LATEST... WITH THE PROSPECTS OF VFR CONDITIONS BY 13-15Z AT ALL TAF SITES. ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS WILL BE POSSIBLE AGAIN ON THURSDAY ACROSS ALL OF CENTRAL NC. HOWEVER... THE PROBABILITY AT A GIVEN SITE IS TOO LOW TO INCLUDE IN THE TAFS AT THIS TIME. OUTLOOK... EARLY MORNING STRATUS/FOG...ALONG WITH AFTERNOON SHOWERS AND STORMS WILL BE POSSIBLE EACH DAY THIS WEEK. A BACKDOOR COLD FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...WHICH MAY BRING ANOTHER PERIOD UNSETTLED WEATHER FOR PORTIONS OF THE AREA. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PWB NEAR TERM...CBL/BLS SHORT TERM...CBL LONG TERM...KRD AVIATION...CBL/BLS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1145 AM EDT THU AUG 21 2014 .SYNOPSIS... A WARM FRONT WILL PIVOT INTO CENTRAL PENNSYLVANIA THROUGH TONIGHT. UPPER TROUGHING MOVING EAST FROM THE GREAT LAKES ACROSS THE NORTHEAST STATES INTO THE CANADIAN MARITIME REGION WILL PUSH THE FRONT BACK TO THE SOUTH ALONG THE EAST COAST THIS WEEKEND...ALLOWING A LARGE AREA OF HIGH PRESSURE OVER NORTHERN NEW ENGLAND TO RIDGE SOUTHWEST ALONG THE EAST-SIDE OF THE APPALACHIANS THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... ISOLATED TO LOCALLY SCATTERED COVERAGE OF SHOWERS EXPECT THIS AFTERNOON AS BROAD UPPER SHEAR AXIS LIES ACROSS PA. PW IS MUCH LOWER THAN YESTERDAY...ALONG WITH STRONGER NW FLOW ALOFT. THESE TWO FACTORS SHOULD RESULT IN LITTLE CONCERN FOR HEAVY RAINERS THIS AFTERNOON...AND JUST GENERIC OVERALL SHOWER/THUNDERSTORM CHANCES THROUGH THIS EVENING. A MOIST/MODESTLY UNSTABLE AIRMASS AND RELATIVELY STEEP MID LVL LAPSE RATES WILL YIELD HIGHEST POPS /40-60%/ DURING PEAK HEATING IN THE 18-00Z TIME WINDOW. HRRR IS LESS THAN IMPRESSIVE... GENERALLY INDICATING ISOLATED TO SCATTERED COVERAGE IN MOST PLACES. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... UPPER LOW WILL BE PASSING INTO NEW ENG BY FRI MORNING. HOWEVER..SHORT TERM MDL DATA ALL TRACKING A TRAILING SHORTWAVE SEWRD THRU CENTRAL PA FRIDAY PM...WHICH WILL LIKELY BRING ANOTHER ROUND OF SHRA/TSRA TO THE AREA. HIGHEST /LIKELY/ POPS PLACED ALONG AND SW OF QUASI-STATIONARY FRONT...WHICH MDLS PLACE ROUGHLY FROM KBFD SE TO KTHV. SOUTH AND WEST OF THIS BNDRY...UNSTABLE SOUNDINGS AND HIGH PWATS COULD RESULT IN LOCALLY HVY RAINFALL IN TSRA. CONVECTION- ALLOWING MDLS PRODUCING ISOLATED SPOTS AMTS OF ARND 4 INCHES. HOWEVER...AVERAGE AMTS BASED ON BLENDED QPF SHOULD BE LESS THAN A HALF INCH. GEFS 925 TEMPS ARE SUPPORTIVE OF MAX TEMPS NR SEASONAL LEVELS FRIDAY. CONVECTION SHOULD DIMINISH AND PUSH SOUTH OF THE STATE FRIDAY NIGHT...AS SHORTWAVE DIVES SOUTH OF THE AREA. BEHIND THIS FEATURE...BACKDOOR COLD FRONT IS PROGGED TO WORK SWRD THRU CENTRAL PA FRI NIGHT. MOIST EASTERLY FLOW ASCENDING THE APPALACHIANS MAY PRODUCE LOW CLOUDS AND SPOTTY DRIZZLE LATE FRIDAY NIGHT. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... LARGE SFC HIGH OVR NEW ENG WILL BE THE PRIMARY DRIVER OF OUR WX THRU MOST OF THE EXTENDED FCST. MOIST...EASTERLY FLOW OFF THE ATLANTIC WILL LIKELY PRODUCE A DULL AND COOL SATURDAY...WITH AM LOW CLOUDS GIVING WAY TO A BIT OF BRIGHTENING BY AFTN. GEFS 925 TEMPS OF ONLY 16C-18C IMPLY MAX TEMPS FROM JUST THE U60S OVR THE HIGH TERRAIN OF THE CENTRAL MTNS...TO THE M70S OVR THE SUSQ VALLEY. MED RANGE GUIDANCE INDICATES HIGH PRES AND ASSOC DRY AIR MASS WILL DRIFT SOUTH LATE THIS WEEKEND...BRINGING FAIR AND BRIGHTER WX TO CENTRAL PA. PTSUNNY SKIES SHOULD HELP TEMPS REBOUND A BIT ON SUNDAY...BUT STILL REMAIN BLW NORMAL. EARLIER CONCERNS OF CENTRAL PA DEALING WITH RING OF FIRE CONVECTION APPEAR TO BE WANING...AS LARGE SCALE SUBSIDENCE AND DRY AIR ARE THE THEMES OF THE MED RANGE GUIDANCE EARLY NEXT WEEK BENEATH SFC RIDGE ALONG THE E COAST. FCST CONFIDENCE BEGINS LOWER BY THE MIDDLE OF NEXT WEEK...WHEN MED RANGE MDLS BEGIN TO DIVERGE. GEFS KEEPS RIDGE AND FAIR WX GOING THRU WED...WHILE ECMWF ENSEMBLE DATA INDICATES A WEAK COLD FRONT COULD PUSH SE INTO THE REGION. THUS...HAVE ADDED A LOW CHC OF TSRA WED. WHAT APPEARS CERTAIN IS THAT THE COOL TEMPS OF THIS WEEKEND WILL GIVE WAY TO A SLOW WARMING TREND THRU THE FIRST HALF OF NEXT WEEK...AS COOL AIR MASS MODIFIES UNDER STILL STRONG AUGUST SUN. GEFS AND EC ENS 850 TEMPS SUPPORT HIGH RETURNING TO ABV NORMAL BY WED. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... HI RES MODELS CONT TO DEPICT ISOLD SHRA AND TSTMS OVER CENTRAL PA THIS AFTERNOON. SPARSE COVERAGE RESULTS IN LOW CONFIDENCE IN POINT TERMINAL IMPACTS...SO WILL INDICATE VCSH MENTION THROUGH THIS EVENING. ANTICIPATE DECREASING COVERAGE OF SHRA AND TSTMS INTO THE EVE/OVERNIGHT PERIOD WITH AREAS OF FOG/ST POSSIBLY RE- DEVELOPING WITH SOME CLEARING/LGT WINDS/MOIST AIRMASS ESP IN THE NORTH. WILL NEED TO WATCH UPSTREAM IN THE OH VLY FOR POSSIBLE CONVECTIVE COMPLEX. FOR NOW EXPECT THIS MESOSCALE SYSTEM TO STAY SW OF THE AIRSPACE FROM OH TO WV. OUTLOOK... FRI-SAT...AM LOW CIGS/FOG FOLLOWED BY SCT SHOWERS/TSTMS AND BRIEF MVFR/IFR RESTRICTIONS. SUN-MON...AM LOW CIGS PSBL. OTHERWISE MAINLY VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...DEVOIR/STEINBUGL SHORT TERM...FITZGERALD LONG TERM...FITZGERALD AVIATION...DEVOIR/STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1129 AM EDT THU AUG 21 2014 .SYNOPSIS... A WARM FRONT WILL PIVOT INTO CENTRAL PENNSYLVANIA THROUGH TONIGHT. UPPER TROUGHING MOVING EAST FROM THE GREAT LAKES ACROSS THE NORTHEAST STATES INTO THE CANADIAN MARITIME REGION WILL PUSH THE FRONT BACK TO THE SOUTH ALONG THE EAST COAST THIS WEEKEND...ALLOWING A LARGE AREA OF HIGH PRESSURE OVER NORTHERN NEW ENGLAND TO RIDGE SOUTHWEST ALONG THE EAST-SIDE OF THE APPALACHIANS THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... ISOLATED TO LOCALLY SCATTERED COVERAGE OF SHOWERS EXPECT THIS AFTERNOON AS BROAD UPPER SHEAR AXIS LIES ACROSS PA. PW IS MUCH LOWER THAN YESTERDAY...ALONG WITH STRONGER NW FLOW ALOFT. THESE TWO FACTORS SHOULD RESULT IN LITTLE CONCERN FOR HEAVY RAINERS THIS AFTERNOON...AND JUST GENERIC OVERALL SHOWER/THUNDERSTORM CHANCES THROUGH THIS EVENING. A MOIST/MODESTLY UNSTABLE AIRMASS AND RELATIVELY STEEP MID LVL LAPSE RATES WILL YIELD HIGHEST POPS /40-60%/ DURING PEAK HEATING IN THE 18-00Z TIME WINDOW. HRRR IS LESS THAN IMPRESSIVE... GENERALLY INDICATING ISOLATED TO SCATTERED COVERAGE IN MOST PLACES. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... UPPER LOW WILL BE PASSING INTO NEW ENG BY FRI MORNING. HOWEVER..SHORT TERM MDL DATA ALL TRACKING A TRAILING SHORTWAVE SEWRD THRU CENTRAL PA FRIDAY PM...WHICH WILL LIKELY BRING ANOTHER ROUND OF SHRA/TSRA TO THE AREA. HIGHEST /LIKELY/ POPS PLACED ALONG AND SW OF QUASI-STATIONARY FRONT...WHICH MDLS PLACE ROUGHLY FROM KBFD SE TO KTHV. SOUTH AND WEST OF THIS BNDRY...UNSTABLE SOUNDINGS AND HIGH PWATS COULD RESULT IN LOCALLY HVY RAINFALL IN TSRA. CONVECTION- ALLOWING MDLS PRODUCING ISOLATED SPOTS AMTS OF ARND 4 INCHES. HOWEVER...AVERAGE AMTS BASED ON BLENDED QPF SHOULD BE LESS THAN A HALF INCH. GEFS 925 TEMPS ARE SUPPORTIVE OF MAX TEMPS NR SEASONAL LEVELS FRIDAY. CONVECTION SHOULD DIMINISH AND PUSH SOUTH OF THE STATE FRIDAY NIGHT...AS SHORTWAVE DIVES SOUTH OF THE AREA. BEHIND THIS FEATURE...BACKDOOR COLD FRONT IS PROGGED TO WORK SWRD THRU CENTRAL PA FRI NIGHT. MOIST EASTERLY FLOW ASCENDING THE APPALACHIANS MAY PRODUCE LOW CLOUDS AND SPOTTY DRIZZLE LATE FRIDAY NIGHT. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... LARGE SFC HIGH OVR NEW ENG WILL BE THE PRIMARY DRIVER OF OUR WX THRU MOST OF THE EXTENDED FCST. MOIST...EASTERLY FLOW OFF THE ATLANTIC WILL LIKELY PRODUCE A DULL AND COOL SATURDAY...WITH AM LOW CLOUDS GIVING WAY TO A BIT OF BRIGHTENING BY AFTN. GEFS 925 TEMPS OF ONLY 16C-18C IMPLY MAX TEMPS FROM JUST THE U60S OVR THE HIGH TERRAIN OF THE CENTRAL MTNS...TO THE M70S OVR THE SUSQ VALLEY. MED RANGE GUIDANCE INDICATES HIGH PRES AND ASSOC DRY AIR MASS WILL DRIFT SOUTH LATE THIS WEEKEND...BRINGING FAIR AND BRIGHTER WX TO CENTRAL PA. PTSUNNY SKIES SHOULD HELP TEMPS REBOUND A BIT ON SUNDAY...BUT STILL REMAIN BLW NORMAL. EARLIER CONCERNS OF CENTRAL PA DEALING WITH RING OF FIRE CONVECTION APPEAR TO BE WANING...AS LARGE SCALE SUBSIDENCE AND DRY AIR ARE THE THEMES OF THE MED RANGE GUIDANCE EARLY NEXT WEEK BENEATH SFC RIDGE ALONG THE E COAST. FCST CONFIDENCE BEGINS LOWER BY THE MIDDLE OF NEXT WEEK...WHEN MED RANGE MDLS BEGIN TO DIVERGE. GEFS KEEPS RIDGE AND FAIR WX GOING THRU WED...WHILE ECMWF ENSEMBLE DATA INDICATES A WEAK COLD FRONT COULD PUSH SE INTO THE REGION. THUS...HAVE ADDED A LOW CHC OF TSRA WED. WHAT APPEARS CERTAIN IS THAT THE COOL TEMPS OF THIS WEEKEND WILL GIVE WAY TO A SLOW WARMING TREND THRU THE FIRST HALF OF NEXT WEEK...AS COOL AIR MASS MODIFIES UNDER STILL STRONG AUGUST SUN. GEFS AND EC ENS 850 TEMPS SUPPORT HIGH RETURNING TO ABV NORMAL BY WED. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... FOG AND LOW CLOUDS /IFR-LIFR CONDITIONS/ WILL GIVE WAY TO VFR BY 13-14Z. LATEST COSPA/HRRR INDICATES MORE DISORGANIZED WDLY SCT SHRA AND TSTMS DEVELOPING THIS AFTN/MAINLY AFTER 17Z. EXPECTED SPARSE COVERAGE/LOW CONFIDENCE IN POINT-TERMINAL IMPACTS WILL LIMIT VCTS MENTION ATTM...AND WILL ALLOW THIS TO BE ADDRESSED WITH THE 15Z INTERMEDIATE UPDATE AND 18Z SCHEDULED ISSUANCE. ANTICIPATE DECREASING COVERAGE OF SHRA AND TSTMS INTO THE EVE/OVERNIGHT PERIOD WITH AREAS OF FOG/ST POSSIBLY RE-DEVELOPING WITH SOME CLEARING/LGT WINDS/MOIST AIRMASS ESP IN THE NORTH. WILL NEED TO WATCH UPSTREAM IN THE OH VLY FOR POSSIBLE CONVECTIVE COMPLEX. FOR NOW EXPECT THIS MESOSCALE SYSTEM TO STAY SW OF THE AIRSPACE FROM OH TO WV. OUTLOOK... FRI-SAT...AM LOW CIGS/FOG FOLLOWED BY SCT SHOWERS/TSTMS AND BRIEF MVFR/IFR RESTRICTIONS. SUN-MON...AM LOW CIGS PSBL. OTHERWISE MAINLY VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...DEVOIR/STEINBUGL SHORT TERM...FITZGERALD LONG TERM...FITZGERALD AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
246 AM EDT THU AUG 21 2014 .SYNOPSIS... AN UPPER LOW OVER THE GREAT LAKES WILL DRIFT SLOWLY SOUTHEAST ACROSS UPSTATE NY AND NEW ENGLAND BY THE WEEKEND. A LARGE AREA OF HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL RIDGE SOUTHWARD ALONG THE EAST-SIDE OF THE APPALACHIANS INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... WATER VAPOR LOOP AT 05Z SHOWING SHORTWAVE OVR WESTERN PA ROTATING THRU BASE OF UPPER LOW. THIS FEATURE IS SUSTAINING LINGERING CONVECTION ACROSS THE CENTRAL MTNS AT 05Z AND LATEST RAP/HRRR OUTPUT SUGGEST DWINDLING SHRA AND A FEW TSRA WILL PUSH INTO THE EASTERN COUNTIES BEFORE EXITING THE AREA ARND DAWN. BASED ON RADAR TRENDS AND RAP/HRRR DATA...WILL MAINTAIN HIGHEST /CHC/ POPS ACROSS THE MID SUSQ VALLEY AND MTNS N OF IPT DURING THE PRE-DAWN HOURS. WET GROUND...LGT WIND AND CLEARING SKIES BEHIND SHORTWAVE SHOULD PROMOTE AREAS OF FOG EARLY THIS MORNING. DWPTS INDICATE MIN TEMPS WILL RANGE FROM THE L/M60S ACROSS THE REGION. && .SHORT TERM /7 AM THIS MORNING THROUGH 6 PM FRIDAY/... THE HRRR IS PRETTY POSITIVE ON LITTLE OR NO CONVECTION IN THE EARLY MORNING. THE CONVECTION AND WAVE IT HAS IN THE MIDWEST IS FORECAST TO DRIVE INTO THE OHIO VALLEY. LARGER SCALE MODELS SHOW OUR PW VALUES ARE RELATIVELY LOW IN THE MORNING AND ARE FORECAST TO SLOWLY RISE DURING THE DAY AND INTO THE EVENING. THE CAPE IN MOST MODELS COMES UP INTO THE 600 TO 1800JKG-1 RANGE SECOND HALF OF THE DAY. BEST CHANCE OF SHOWERS AND THUNDERSTORMS WOULD BE IN THE AFTERNOON. MOST GUIDANCE STILL TENDS TO SUPPORT THIS. OLDER SREF AND OTHER MODELS SEEM TO IMPLY THIS WITH MORE MEMBERS WITH RAIN LATER IN DAY. IMPLIED LULL IS IN THE 09 TO 18Z TIMEFRAME. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... CURRENT MID RANGE MODEL GUIDANCE PUTS US IN A RING OF FIRE PATTERN LATE THIS WEEK AND INTO THE WEEKEND...WITH AFTERNOON CONVECTION POSSIBLE ON FRIDAY AND SATURDAY. STRONG FLOW ALOFT SHOULD ENHANCE THIS POSSIBILITY THOUGH LACK OF MOISTURE OF FRIDAY COULD INHIBIT CONVECTION. GEFS IS SHOWING PWAT ANOMALIES ON SATURDAY AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD THE REGION FROM THE MIDWEST. CURRENT SET UP FOCUSES THREAT ON WESTERN AND CENTRAL PA...WHERE EASTERN PA IS LIKELY TO REMAIN DRY. DESPITE APPROACH OF UPPER RIDGE...NO BIG WARMUP EXPECTED...AS LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN EASTERLY FLOW INTO CENTRAL PA. TEMPS THIS WEEKEND LOOK TO BE BELOW NORMAL. THERE MAY BE ISSUES WITH AM LOW CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA. DRIER WEATHER LOOKS TO BE IN STORE INTO EARLY NEXT WEEK AS RIDGE BUILDS OVER THE REGION. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... UPPER LEVEL S/WV CURRENTLY ROTATING ACROSS CENTRAL PA IS HELPING TO SUSTAIN ISOLD CONVECTION OVER THE AIRSPACE EARLY THIS MORNING. ONLY TERMINAL IMPACT ATTM APPEARS TO BE IPT WHICH SHOULD GET A -SHRA WITH A FEW LTG STRIKES NEARBY 07-08Z. HRRR/COSPA DATA SHOWS LINGERING SHOWERS DISSIPATING OR MOVG E THROUGH DAYBREAK. FOG AND LOW CLOUDS LKLY TO BE MORE OF A FACTOR EARLY THIS MORNING GIVEN RECENT RAIN/WET GROUND...LIGHT WINDS AND HIGH BOUNDARY LAYER MOISTURE/SFC DEWPOINTS IN THE 60S. CUT BACK ON EXTENT OF IFR CONDS FROM PREVIOUS FCST WITH HIGHEST CONFIDENCE AT TERMINALS THAT RECEIVED DECENT RAINFALL YESTERDAY. REDUCED CONDITIONS SHOULD IMPROVE TO VFR BY MID-LATE MORNING. A CONSENSUS OF HIRES MDL GUIDANCE INDICATES MORE DISORGANIZED/WDLY SCT SHRA AND TSTMS DEVELOPING THIS AFTN. WILL LKLY ADD SOME MENTION INTO 12Z TAFS BUT FOR NOW WENT WITH SCT-BKN 040-050. ANTICIPATE DECREASING CVRG OF SHRA AND TSTMS INTO THE LATE EVE/OVERNIGHT PERIOD WITH AREAS OF FOG/ST DEVELOPING AGAIN WITH SOME CLEARING/LGT WINDS/MOIST AIRMASS. OUTLOOK... FRI-SAT...AM LOW CIGS/FOG FOLLOWED BY SCT SHOWERS/TSTMS AND BRIEF MVFR/IFR RESTRICTIONS. SUN-MON...AM LOW CIGS PSBL. OTHERWISE MAINLY VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...FITZGERALD SHORT TERM...GRUMM LONG TERM...FITZGERALD/CERU AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
105 AM EDT THU AUG 21 2014 .SYNOPSIS... AN UPPER LOW OVER THE GREAT LAKES WILL DRIFT SLOWLY SOUTHEAST ACROSS UPSTATE NY AND NEW ENGLAND BY THE WEEKEND. A LARGE AREA OF HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL RIDGE SOUTHWARD ALONG THE EAST-SIDE OF THE APPALACHIANS INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... WATER VAPOR LOOP AT 05Z SHOWING SHORTWAVE OVR WESTERN PA ROTATING THRU BASE OF UPPER LOW. THIS FEATURE IS SUSTAINING LINGERING CONVECTION ACROSS THE CENTRAL MTNS AT 05Z AND LATEST RAP/HRRR OUTPUT SUGGEST DWINDLING SHRA AND A FEW TSRA WILL PUSH INTO THE EASTERN COUNTIES BEFORE EXITING THE AREA ARND DAWN. BASED ON RADAR TRENDS AND RAP/HRRR DATA...WILL MAINTAIN HIGHEST /CHC/ POPS ACROSS THE MID SUSQ VALLEY AND MTNS N OF IPT DURING THE PRE-DAWN HOURS. WET GROUND...LGT WIND AND CLEARING SKIES BEHIND SHORTWAVE SHOULD PROMOTE AREAS OF FOG EARLY THIS MORNING. DWPTS INDICATE MIN TEMPS WILL RANGE FROM THE L/M60S ACROSS THE REGION. && .SHORT TERM /7 AM THIS MORNING THROUGH 6 PM FRIDAY/... THE HRRR IS PRETTY POSITIVE ON LITTLE OR NO CONVECTION IN THE EARLY MORNING. THE CONVECTION AND WAVE IT HAS IN THE MIDWEST IS FORECAST TO DRIVE INTO THE OHIO VALLEY. LARGER SCALE MODELS SHOW OUR PW VALUES ARE RELATIVELY LOW IN THE MORNING AND ARE FORECAST TO SLOWLY RISE DURING THE DAY AND INTO THE EVENING. THE CAPE IN MOST MODELS COMES UP INTO THE 600 TO 1800JKG-1 RANGE SECOND HALF OF THE DAY. BEST CHANCE OF SHOWERS AND THUNDERSTORMS WOULD BE IN THE AFTERNOON. MOST GUIDANCE STILL TENDS TO SUPPORT THIS. OLDER SREF AND OTHER MODELS SEEM TO IMPLY THIS WITH MORE MEMBERS WITH RAIN LATER IN DAY. IMPLIED LULL IS IN THE 09 TO 18Z TIMEFRAME. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... CURRENT MID RANGE MODEL GUIDANCE PUTS US IN A RING OF FIRE PATTERN LATE THIS WEEK AND INTO THE WEEKEND...WITH AFTERNOON CONVECTION POSSIBLE ON FRIDAY AND SATURDAY. STRONG FLOW ALOFT SHOULD ENHANCE THIS POSSIBILITY THOUGH LACK OF MOISTURE OF FRIDAY COULD INHIBIT CONVECTION. GEFS IS SHOWING PWAT ANOMALIES ON SATURDAY AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD THE REGION FROM THE MIDWEST. CURRENT SET UP FOCUSES THREAT ON WESTERN AND CENTRAL PA...WHERE EASTERN PA IS LIKELY TO REMAIN DRY. DESPITE APPROACH OF UPPER RIDGE...NO BIG WARMUP EXPECTED...AS LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN EASTERLY FLOW INTO CENTRAL PA. TEMPS THIS WEEKEND LOOK TO BE BELOW NORMAL. THERE MAY BE ISSUES WITH AM LOW CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA. DRIER WEATHER LOOKS TO BE IN STORE INTO EARLY NEXT WEEK AS RIDGE BUILDS OVER THE REGION. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... NOT A LOT OF CHANGE TO 03Z TAFS. EARLIER DISCUSSION BELOW. DID NOT CHANGE A LOT ON THE 00Z TAF PACKAGE FROM THE EARLIER SET. MAIN CONCERN IS CONVECTION ACROSS THE NW NEAR BFD. OTHER WIDELY SCATTERED SHOWERS AND STORMS COULD MOVE EAST INTO THE REST OF THE AREA OVERNIGHT. MAIN ISSUE FOR AVN CONCERN OVERNIGHT WILL BE FOG AND LOW CLOUDS WITH LGT/VRB WINDS AND HIGH BLYR MSTR/SFC DEWPOINTS. FOR THIS...WENT CLOSE TO EARLIER FCST. DID LOWER CIGS IN SOME CASES. A BLEND OF GUIDANCE AND TIMING FROM LAST NIGHT. FOR THU...EXPECT LESS SHOWER AND THUNDERSTORM ACTIVITY...AS THE WIND SHIFT LINE AND DYNAMICS SHIFT EASTWARD. OUTLOOK... FRI-SAT...AM LOW CLOUDS/FOG FOLLOWED BY PERIODS OF SHOWERS/TSTMS AND BRIEF MVFR/IFR RESTRICTIONS. SUN-MON...MAINLY VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...FITZGERALD SHORT TERM...GRUMM LONG TERM...FITZGERALD/CERU AVIATION...MARTIN/STEINBUGL
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1051 AM CDT THU AUG 21 2014 .DISCUSSION... PER TRENDS SO FAR THIS MORNING IT LOOKS LIKE THE SLUG OF DEEPER TROPICAL MOISTURE HAS SHIFTED TO THE EAST AND THINGS ARE DRYING OUT ACROSS MOST OF OUR CWA. NO CHANGES PLANNED ATTM AS THE CUR- RENT FCST LOOKS TO BE ON TRACK. 41 && .PREV DISCUSSION... /ISSUED 347 AM CDT THU AUG 21 2014/ SOME OBSERVATIONS ARE NOW INDICATING LOW CLOUDS STARTING TO FORM TONIGHT. THESE WILL QUICKLY BURN OFF THIS AFTERNOON ALLOWING FOR ANOTHER HOT AND MUGGY DAY. CHANCE OF RAIN TODAY WILL BE FAR LESS THAN YESTERDAY. AT 250 MB BEST UPPER LEVEL DIFFLUENCE IS OFF TO THE EAST OF THE AREA THANKS TO AN UPPER LEVEL RIDGE MOVING INTO CENTRAL TEXAS. AT 500 MB HEIGHTS HAVE ALSO STARTED TO RISE ACROSS SOUTHEAST TEXAS THANKS TO A BUILDING RIDGE. THE RAP PERFORMED PRETTY WELL YESTERDAY AND SHOWS ALMOST NO RAIN FOR SOUTHEAST TEXAS EXCEPT FOR A SPOTTY SHOWER OR TWO IN SAN JACINTO AND LIBERTY COUNTIES LATER THIS AFTERNOON. THE TEXAS TECH WRF ALSO SHOWS THIS. GIVEN THE EVIDENCE FROM THE UPPER LEVEL MAPS MENTIONED ABOVE THIS MAKES SENSE. THE UPPER LEVEL RIDGE WILL CONTINUE TO BUILD AND POSITION ITSELF NEAR THE ARKANSAS/ LOUISIANA BORDER ON FRIDAY. THE HEAT ADVISORY WILL LIKELY BE NEEDED THROUGH THE WEEKEND. BY SUNDAY THE RIDGE WILL BEGIN TO WEAKEN. GFS FORECAST SOUNDINGS STILL SHOW RELATIVELY LOW PWAT AIR IN PLACE FOR THIS TIME OF YEAR AND A CAP IN PLACE AT 850MB. ON MONDAY THE CAP WEAKENS ENOUGH TO INTRODUCE THE CHANCE OF RAIN BACK INTO THE FORECAST. THE CHANCE OF AFTERNOON SHOWERS AND THUNDERSTORMS AND ABOVE NORMAL TEMPERATURES LOOKS TO REMAIN IN PLACE THROUGH NEXT WEDNESDAY. 23 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 98 77 99 77 99 / 10 10 10 10 10 HOUSTON (IAH) 97 77 97 77 97 / 10 10 10 10 10 GALVESTON (GLS) 92 84 92 84 92 / 20 10 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING ZONES: BRAZORIA...CHAMBERS...GALVESTON...JACKSON... MATAGORDA. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
612 AM CDT THU AUG 21 2014 .DISCUSSION... SEE 12Z AVIATION DISCUSSION. && .AVIATION... NO SIGNIFICANT CHANGES TO PREV TAF PACKAGE. FCST SOUNDINGS INDICATE DRIER CONDS WITH PW VALUES DROPPING TO 1.5-1.7 INCHES. RAP/HRRR KEEP MOST OF THE PRECIP TO THE EAST TODAY AS WELL. MVFR CIGS WILL BE POSSIBLE EARLY THIS MORNING WITH CIGS MIXING OUT BETWEEN 14-16Z. SHOULD GET SOME MVFR CIGS AGAIN OVER THE NW TAF SITES AGAIN TOMORROW MORNING. 43 && .PREV DISCUSSION... /ISSUED 347 AM CDT THU AUG 21 2014/ DISCUSSION... SOME OBSERVATIONS ARE NOW INDICATING LOW CLOUDS STARTING TO FORM TONIGHT. THESE WILL QUICKLY BURN OFF THIS AFTERNOON ALLOWING FOR ANOTHER HOT AND MUGGY DAY. CHANCE OF RAIN TODAY WILL BE FAR LESS THAN YESTERDAY. AT 250 MB BEST UPPER LEVEL DIFFLUENCE IS OFF TO THE EAST OF THE AREA THANKS TO AN UPPER LEVEL RIDGE MOVING INTO CENTRAL TEXAS. AT 500 MB HEIGHTS HAVE ALSO STARTED TO RISE ACROSS SOUTHEAST TEXAS THANKS TO A BUILDING RIDGE. THE RAP PERFORMED PRETTY WELL YESTERDAY AND SHOWS ALMOST NO RAIN FOR SOUTHEAST TEXAS EXCEPT FOR A SPOTTY SHOWER OR TWO IN SAN JACINTO AND LIBERTY COUNTIES LATER THIS AFTERNOON. THE TEXAS TECH WRF ALSO SHOWS THIS. GIVEN THE EVIDENCE FROM THE UPPER LEVEL MAPS MENTIONED ABOVE THIS MAKES SENSE. THE UPPER LEVEL RIDGE WILL CONTINUE TO BUILD AND POSITION ITSELF NEAR THE ARKANSAS/ LOUISIANA BORDER ON FRIDAY. THE HEAT ADVISORY WILL LIKELY BE NEEDED THROUGH THE WEEKEND. BY SUNDAY THE RIDGE WILL BEGIN TO WEAKEN. GFS FORECAST SOUNDINGS STILL SHOW RELATIVELY LOW PWAT AIR IN PLACE FOR THIS TIME OF YEAR AND A CAP IN PLACE AT 850MB. ON MONDAY THE CAP WEAKENS ENOUGH TO INTRODUCE THE CHANCE OF RAIN BACK INTO THE FORECAST. THE CHANCE OF AFTERNOON SHOWERS AND THUNDERSTORMS AND ABOVE NORMAL TEMPERATURES LOOKS TO REMAIN IN PLACE THROUGH NEXT WEDNESDAY. 23 MARINE... MODERATE ONSHORE WINDS WILL PERSIST THROUGH TONIGHT AND BEGIN TO RELAX BY FRIDAY MORNING. WILL MAINTAIN THE SCEC FOR THE GULF WATERS THROUGH THE EARLY MORNING. SURFACE HIGH PRESSURE WILL BE CENTERED OVER THE WESTERN GULF BY SUNDAY MORNING AND THE PRESSURE GRADIENT WILL SLACKEN CONSIDERABLY. LIGHT WINDS ARE EXPECTED OVER THE WEEKEND AND INTO THE FIRST HALF OF NEXT WEEK. 43 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 98 77 99 77 99 / 10 10 10 10 10 HOUSTON (IAH) 97 77 97 77 97 / 10 10 10 10 10 GALVESTON (GLS) 92 84 92 84 92 / 20 10 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING ZONES: BRAZORIA...CHAMBERS...GALVESTON...JACKSON... MATAGORDA. GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 10 AM CDT THIS MORNING FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM. && $$ DISCUSSION...23 AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
347 AM CDT THU AUG 21 2014 .DISCUSSION... SOME OBSERVATIONS ARE NOW INDICATING LOW CLOUDS STARTING TO FORM TONIGHT. THESE WILL QUICKLY BURN OFF THIS AFTERNOON ALLOWING FOR ANOTHER HOT AND MUGGY DAY. CHANCE OF RAIN TODAY WILL BE FAR LESS THAN YESTERDAY. AT 250 MB BEST UPPER LEVEL DIFFLUENCE IS OFF TO THE EAST OF THE AREA THANKS TO AN UPPER LEVEL RIDGE MOVING INTO CENTRAL TEXAS. AT 500 MB HEIGHTS HAVE ALSO STARTED TO RISE ACROSS SOUTHEAST TEXAS THANKS TO A BUILDING RIDGE. THE RAP PERFORMED PRETTY WELL YESTERDAY AND SHOWS ALMOST NO RAIN FOR SOUTHEAST TEXAS EXCEPT FOR A SPOTTY SHOWER OR TWO IN SAN JACINTO AND LIBERTY COUNTIES LATER THIS AFTERNOON. THE TEXAS TECH WRF ALSO SHOWS THIS. GIVEN THE EVIDENCE FROM THE UPPER LEVEL MAPS MENTIONED ABOVE THIS MAKES SENSE. THE UPPER LEVEL RIDGE WILL CONTINUE TO BUILD AND POSITION ITSELF NEAR THE ARKANSAS/ LOUISIANA BORDER ON FRIDAY. THE HEAT ADVISORY WILL LIKELY BE NEEDED THROUGH THE WEEKEND. BY SUNDAY THE RIDGE WILL BEGIN TO WEAKEN. GFS FORECAST SOUNDINGS STILL SHOW RELATIVELY LOW PWAT AIR IN PLACE FOR THIS TIME OF YEAR AND A CAP IN PLACE AT 850MB. ON MONDAY THE CAP WEAKENS ENOUGH TO INTRODUCE THE CHANCE OF RAIN BACK INTO THE FORECAST. THE CHANCE OF AFTERNOON SHOWERS AND THUNDERSTORMS AND ABOVE NORMAL TEMPERATURES LOOKS TO REMAIN IN PLACE THROUGH NEXT WEDNESDAY. 23 && .MARINE... MODERATE ONSHORE WINDS WILL PERSIST THROUGH TONIGHT AND BEGIN TO RELAX BY FRIDAY MORNING. WILL MAINTAIN THE SCEC FOR THE GULF WATERS THROUGH THE EARLY MORNING. SURFACE HIGH PRESSURE WILL BE CENTERED OVER THE WESTERN GULF BY SUNDAY MORNING AND THE PRESSURE GRADIENT WILL SLACKEN CONSIDERABLY. LIGHT WINDS ARE EXPECTED OVER THE WEEKEND AND INTO THE FIRST HALF OF NEXT WEEK. 43 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 98 77 99 77 99 / 10 10 10 10 10 HOUSTON (IAH) 97 77 97 77 97 / 10 10 10 10 10 GALVESTON (GLS) 92 84 92 84 92 / 20 10 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING ZONES: BRAZORIA...CHAMBERS...GALVESTON...JACKSON... MATAGORDA. GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 7 AM CDT THIS MORNING FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. && $$ DISCUSSION...23 AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
240 AM EDT THU AUG 21 2014 .SYNOPSIS... A WEAK STATIONARY FRONT WILL REMAIN IN THE AREA THROUGH THE REST OF THE WEEK. UPPER LEVEL DISTURBANCES TRACKING EAST AND SOUTHEAST ACROSS THE BOUNDARY WILL BRING SCATTERED SHOWERS AND STORMS TO THE REGION EACH DAY. THE FRONT SHOULD SHIFT BACK SOUTH OF THE REGION SATURDAY BRINGING A RETURN TO COOLER WEATHER FOR THE WEEKEND. && .NEAR TERM /THROUGH TODAY/... AS OF 1120 PM EDT WEDNESDAY... MLCAPES OVER 1500 J/KG STILL LINGERING OVER THE PIEDMONT LATE THIS EVENING KEEPING CONVECTION ONGOING FROM THE NC/VA LINE NORTH INTO BUCKINGHAM COUNTY. AIRMASS HAS BEEN WORKED OVER ACROSS THE MTNS...AND DESPITE A STRONGER WAVE DEPICTED BY LATEST RAP ANALYSIS OVER KY...NOT SEEING MUCH OF ANYTHING EXCEPT ISOLATED/WIDELY SCATTERED SHOWER THREAT THROUGH 3 AM OUT OVER FAR SW VA INTO NW NC. THINK THE CONVECTION OUT EAST WILL EXIT THE CWA BY 1 AM. SKIES WILL BE VARIABLY CLOUDY WITH LOTS OF HIGH CLOUDINESS ACROSS THE WEST AND SOUTH. CLEARING TAKES PLACE INTO EARLY MORNING OUT EAST...WITH MORE CLOUDS ARRIVING INTO THE APPALACHIANS AHEAD OF THE NEXT SHORTWAVE MOVING OVER ILLINOIS THIS EVENING. MODELS HAVE SLOWED TIMING DOWN SOME WITH ONSET OF NEXT ROUND OF SHOWERS IN THE MTNS...SO DELAYED CHANCES A COUPLE OF HOURS. FOG MAY BE MORE OF AN ISSUE OUT EAST IF/WHEN IT CLEARS ESPECIALLY WHERE IT RAINED. FOR NOW KEPT IN PATCHY FOG...WITH AREAS CLOSER TO BUCKINGHAM COUNTY. LOW TEMPS REMAIN MUGGY IN THE 60S. WEAK RESIDUAL FRONT WILL LIFT BACK NE ON THURSDAY AS THE WAVE CHANNEL ALOFT AROUND THE RIDGE TO THE SW AMPLIFIES A BIT AND STARTS TO SHIFT NORTH AS WELL. MODELS BRING ANOTHER IMPULSE QUICKLY SE OUT OF THE UPSTREAM CONVEYER BELT AND DRIVE IT TOWARD THE NW COUNTIES THURSDAY MORNING SIMILAR TO TODAY...PERHAPS JUST A BIT SLOWER. HOWEVER LIFT WILL BE ENCOUNTERING DEEP NW FLOW SO UNCERTAIN AS TO HOW FAR THIS COMPLEX MAY GET BEFORE FADING. THUS RUNNING WITH INCREASING CHANCE POPS THURSDAY MORNING...MAINLY BLUE RIDGE WEST...WITH HIGHEST ACROSS SE WEST VA. EXPECT EARLY CONVECTION TO AGAIN FADE CROSSING THE RIDGES AS WE SLIP IN BETWEEN WAVES BEFORE BETTER INSTABILITY/OUTFLOW HELPS REDEVELOP AT LEAST SCATTERED AFTERNOON COVERAGE MOUNTAINS...AND ISOLATED OUT EAST WHERE DOWNSLOPE ALOFT WILL BE STRONGER. THEREFORE TRIMMED BACK POPS TO MORE CHANCE NATURE GIVEN TRENDS OF LATE AND LACK OF MUCH LIFT THURSDAY AFTERNOON WITH THE NEXT WAVE IN OHIO. WARMING ALOFT AND WESTERLY WINDS SHOULD COMBINE WITH SUNSHINE TO PUSH TEMPS ABOVE 90 SE WITH 80S MOST OTHER SPOTS PENDING EARLY CLOUDS. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... AS OF 245 PM EDT WEDNESDAY... FORECAST AREA STAYS IN BROAD NORTHWEST SYNOPTIC FLOW. PROBABILITY OF PRECIPITATION WILL DEPEND ON WHEN SHORT WAVES COME THROUGH. SHOWERS AND THUNDERSTORMS THAT CROSS THE COUNTY WARNING AREA DURING THE LATE NIGHT OR EARLY MORNING...OR UPSTREAM CLUSTERS OF STORMS THAT SPREAD CLOUDS DOWNSTREAM OVER US WILL DIMINISH THE AVAILABLE INSTABILITY. MODELS HAVE AXIS OF BEST LIFT SHIFTING JUST NORTH OF THE FORECAST AREA ON FRIDAY. THIS MAY LIMIT THE COVERAGE OF PRECIPITATION FOR FRIDAY THROUGH SATURDAY. BUT SURFACE BOUNDARY POSSIBLY MOVING SOUTH THROUGH THE EASTERN PART OF THE FORECAST AREA ON FRIDAY MAY TRIGGER SHOWERS AND THUNDERSTORMS. PRECIPITABLE WATER VALUES REMAIN HIGH THROUGH THE PERIOD. LARGE RAINFALL RATES WILL BE POSSIBLE IN ANY OF THE STORMS. EXPECTING MUGGY CONDITIONS OVERNIGHT WITH DEW POINTS REMAINING WELL INTO THE 60S. 850 TEMPERATURES ON THE EASTERN SIDE OF THE FORECAST AREA WILL BE COOLER THAN IN THE WEST. OVERALL PRECIPITATION AND CLOUD COVER WILL HOLD TEMPERATURES AT OR JUST BELOW NORMAL FOR MAXIMUM TEMPERATURES. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 300 PM EDT WEDNESDAY... LARGE UPPER RIDGE BUILDS FROM THE LOWER MISSISSIPPI VALLEY. 500 MB HEIGHTS OVER THE FORECAST AREA BEGIN TO RISE ON TUESDAY WITH THE RIDGE CENTERED OVER THE TENNESSEE VALLEY. SURFACE HIGH PRESSURE WILL BE OVER NEW ENGLAND AND WEDGED DOWN THE APPALACHIANS THROUGH TUESDAY. BY THURSDAY A STRONG BERMUDA HIGH WILL BE IN PLACE. CHALLENGING TO TIME SHORT WAVES COMING OVER THE TOP OF THE RIDGE. WPC WAS FAVORING A BLEND OF ENSEMBLE GFS AND ECMWF THROUGH THE PERIOD. THIS KEEPS FORECAST AREA IN A PERSISTENT CHANCE OF PRECIPITATION THROUGH MONDAY NIGHT. AT THIS TIME WILL BE EMPHASIZING SUNDAY NIGHT AS THE BEST CHANCE IN THIS TIME FRAME. WILL BE WARMING UP CLOSER TO ABOVE NORMAL TEMPERATURES ASSOCIATED WITH THE UPPER RIDGE ON WEDNESDAY. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 230 AM EDT THURSDAY... PATCHY MORNING FOG ANTICIPATED AREAWIDE...MAINLY MVFR...BUT CAN`T RULE OUT BRIEF PERIOD OF IFR/LIFR FOR A FEW HOURS AROUND DAYBREAK. ANY FOG AND STRATUS THAT FORMS WILL DISSIPATE AFTER SUNRISE WITH WIDESPREAD VFR CONDITIONS DEVELOPING AFTER 13Z/9AM. SHALLOW EASTERLY SURFACE WINDS THIS MORNING WILL GIVE WAY TO WEST NORTHWEST WINDS LATER THIS MORNING. THE LOW LEVEL FLOW WILL BE FROM THE NORTHWEST TODAY...WINDS 6-12 KTS...AND GUSTY NEAR THE RIDGE CRESTS. THE DEEPER FLOW...WELL ALOFT...IS ALSO FROM THE NORTHWEST. THIS WILL TRANSPORT DEBRIS CLOUDINESS DOWNSTREAM FROM THUNDERSTORMS OVER THE MIDWEST AND OHIO VALLEY REGIONS...CLOUD LAYERS MAINLY ABOVE 10KFT. WITH WINDS OUT OF THE WEST TODAY...THIS WILL CREATE DOWNSLOPE COMPRESSIONAL WARMING AND SUBSIDENCE. DO NOT EXPECT MUCH IN THE WAY OF LOCAL STORM ACTIVITY...DEEP CONVECTION...DUE TO THIS DOWNWARD VERTICAL MOTION. THE SUBSIDENCE IS EXPECTED TO WEAKEN TOWARD SUNSET...THUS POTENTIAL FOR STORM ACTIVITY WILL INCREASE...BUT MAINLY CONFINED LATER IN THE TAF PERIOD. THUNDERSTORMS ARE EXPECTED TO DEVELOP TODAY VCNTY OF STALLED FRONTAL BOUNDARY OVER THE OHIO VALLEY. STORMS WHICH DEVELOP VCNTY OF THIS BOUNDARY...ACROSS IL/IN/OH/KY...WILL MOVE DOWNSTREAM TOWARD THE MID ATLANTIC REGION THIS EVENING AND DURING THE OVERNIGHT TONIGHT. HIGHEST CONFIDENCE FOR STORMS THIS AFTERNOON WILL BE FROM WEST VIRGINIA INTO THE OHIO VALLEY...THE THREAT TRANSITIONING DOWNSTREAM INTO VIRGINIA AND NORTH CAROLINA TONIGHT. INTRODUCED VCNTY TSRA FOR ALL THE TERMINALS AFTER 22Z/6PM...THE STORM THREAT PERSISTING THROUGH THE OVERNIGHT. CONFIDENCE IS HIGHER FOR THE WV TERMINALS. EXTENDED AVIATION... UPPER LEVEL DISTURBANCES WILL BE MOVING THROUGH PERIODICALLY AND INTERACTING WITH A STATIONARY FRONT OVER THE AREA FOR THE NEXT FEW DAYS...RESULTING IN PERIODS OF SHOWERS AND THUNDERSTORMS. DUE TO THE HIGH MOISTURE CONTENT OF THE AIR...EXPECT STRATUS AND FOG DURING THE OVERNIGHT PERIODS WITH AREAS OF MVFR/IFR MOST PRONOUNCED BETWEEN MIDNIGHT AND 9AM EACH DAY. MODELS ARE INDICATED THAT A DEEPER EASTERLY SORT OF WIND FLOW WILL SETUP FOR THIS UPCOMING WEEKEND. THIS SUGGEST THAT LOW CIGS MAY PERSIST EVEN DURING THE DAYTIME PERIODS...SATURDAY AND SUNDAY...WITH WIDESPREAD MVFR CONDITIONS ACROSS THE AREA THIS WEEKEND DUE TO MOISTURE BANKING UP AGAINST THE EAST SIDE OF THE APPALACHIANS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...JH/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...PM
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1039 PM CDT FRI AUG 22 2014 UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE .SHORT TERM...TONIGHT AND SATURDAY ISSUED AT 215 PM CDT FRI AUG 22 2014 THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A WEAK AREA OF LOW PRESSURE SPINNING OVER WESTERN WISCONSIN EARLY THIS AFTERNOON. ALTHOUGH UPPER DIVERGENCE IN THE RIGHT REAR QUAD OF A JET STREAK HAS SHIFTED OFF TO THE EAST...CONVERGENCE NORTH OF A SURFACE WARM FRONT HAS GENERATED SCATTERED SHOWERS AND AN ISOLATED THUNDERSTORM OVER NORTH-CENTRAL WISCONSIN. ALSO OBSERVING RATHER BUBBLY LOOKING CU ALONG A COLD FRONTAL TYPE FEATURE MOVING INTO CENTRAL WISCONSIN THOUGH CONVERGENCE LOOKS QUITE WEAK...AND THE ONLY RETURNS ARE LOCATED OVER NORTHEAST IOWA. THE ATMOSPHERE IS GROWING UNSTABLE AHEAD OF THIS TROUGH/COOL FRONT WITH ML CAPES GROWING TO GREATER THAN 1000 J/KG...AND CIN FALLING RAPIDLY. THE NAM CREATES CONVECTION OVER CENTRAL WISCONSIN LATER THIS AFTERNOON...SO THIS IS SOMETHING TO KEEP AN EYE ON. INCLUDED A ISOLATED THUNDERSTORM MENTION FOR THE REST OF THE AFTERNOON OVER CENTRAL WISCONSIN. MEANWHILE...A LARGE UPPER TROUGH OVER THE PAC NW WILL SHIFT EAST CAUSING A WARM FRONT TO RE-ORGANIZE OVER THE PLAINS ON SATURDAY. PRECIP CHANCES AND FOG POTENTIAL REMAIN THE MAIN FORECAST CONCERNS. TONIGHT...MODELS ARE HAVING A TOUGH TIME LATCHING ON TO THAT LOW LEVEL CIRCULATION OVER WESTERN WISCONSIN. THE NAM AND TO A LESSER EXTEND THE GEM APPEAR TO HAVE A BETTER HANDLE ON THIS FEATURE THAN OTHER GUIDANCE. BUT CONFIDENCE WILL REMAIN LOW IN ANY CASE. BOTH THE NAM AND GEM SHOW THIS SURFACE LOW WEAKENING LATER THIS AFTERNOON OR THIS EVENING AND MORPHING INTO A SURFACE TROUGH OVER CENTRAL AND NORTH-CENTRAL WISCONSIN. THIS WILL KEEP AN ISOLATED TO SCATTERED THREAT OF SHOWERS AND STORMS INTO THE EVENING...AND POSSIBLY INTO THE OVERNIGHT HOURS TOO. THIS TROUGH WILL ALSO PROMOTE FOG DEVELOPMENT IN THESE AREAS TONIGHT AND THINK ANOTHER DENSE FOG ADVISORY WILL BE POSSIBLE FOR THE EARLY MORNING COMMUTE TOMORROW. LIGHT EASTERLY WINDS MAY ALSO ADVECT AREAS OF MARINE FOG INLAND INTO THE LAKESHORE COUNTIES TONIGHT. WARM AND MUGGY WITH LOWS IN THE 60S. SATURDAY...LOW PRESSURE WILL EMERGE INTO THE CENTRAL PLAINS AHEAD OF A DEEP PAC NW TROUGH. THE LOW LEVEL FLOW WILL REORGANIZE AND A WARM FRONT WILL LIFT INTO SOUTHWEST WISCONSIN IN THE AFTERNOON. THIS LOOKS TO BE A LITTLE SLOWER THAN YESTERDAYS RUNS AND WILL BACK OFF PRECIP CHANCES DURING THE MORNING. CHANCES IMPROVE DURING THE AFTERNOON OVER CENTRAL AND NORTH-CENTRAL WISCONSIN BUT AM SKEPTICAL SINCE THE FRONT WILL STILL BE WELL SOUTHWEST OF THE REGION AND MID-LEVEL RIDGING SHARPENS ALOFT. SO WILL MATCH WITH OTHER OFFICES BUT BRING UP CONCERN TO THE NEXT SHIFT. ONCE THE MORNING FOG AND LOW CLOUDS BURN OFF...CONTINUED WARM AND HUMID WITH HIGHS IN THE UPPER 70S TO LOWER 80S. .LONG TERM...SATURDAY NIGHT THROUGH FRIDAY ISSUED AT 215 PM CDT FRI AUG 22 2014 SATURDAY NIGHT INTO SUNDAY...THE UPPER RIDGE GETS NUDGED TO THE EAST A TAD WHILE A BROAD UPPER TROUGH APPROACHES FROM THE NORTHERN AND CENTRAL PLAINS. A DEEPENING LOW PRESSURE SYSTEM WILL LIFT NORTHWARD OVER THE NORTHERN PLAINS...AND LIFT A WARM FRONT NORTH OVER THE AREA. SOME PROGS GENERATE SOME CONVECTION WITH THIS FRONT SAT NIGHT INTO SUNDAY MORNING. CONVECTION MAY STRUGGLE TO DEVELOP DUE TO PROXIMITY TO THE UPPER RIDGE SO KEPT POPS ON THE LOW SIDE AND DECREASED THE DURATION OF THE CONVECTION MENTION. ISOLATED CONVECTION MAY LINGER SUNDAY MORNING ACROSS NORTHERN WISCONSIN...BUT BY NOON THE H850 BOUNDARY IS PROGGED TO BE WELL NORTH OF THE AREA. ANY PRECIPITATION CHANCES DURING THIS PERIOD WILL TEND TO BE FOCUSED TOWARD NORTHWEST WISCONSIN TOWARD THE BEST HEIGHT FALLS. SUNDAY NIGHT INTO MONDAY...NEXT CHANCE OF CONVECTION ALONG A TROUGH OR WEAKENING COLD FRONT. MOST MODEL RUNS DIMINISH THE PCPN AS IT WORKS INTO EASTERN WISCONSIN CLOSER TO THE UPPER RIDGE WHICH REMAINS OVER THE EASTERN GREAT LAKES AND MUCH OF THE EAST THIRD OF THE COUNTRY. THE BRUNT OF THE CONVECTION WILL LIKELY TRACK OVER NORTHWEST WISCONSIN AND ESPECIALLY OVER MINNESOTA NEAR THE SURFACE AND 850 LOW LIFTING NORTHEAST. MONDAY NIGHT...BROAD RRQ REGION OF THE UPPER JET FOCUSES THE CONVECTION OVER THE CENTRAL PLAINS WHILE WHILE WEAK HIGH PRESSURE BUILDS INTO THE REGION IN THE WAKE OF THE FROPA. THE GFS WAS THE ODD MODEL OUT WITH STALLING THE FRONT OVER THE AREA AND CONTINUING CONVECTION MONDAY NIGHT. MOST OF THE MODELS FOR THE REST OF NEXT WEEK...THE UPPER PATTERN SHIFTS FROM A SOUTHWEST FLOW ALOFT TO A NEARLY ZONAL FLOW LATE IN THE WEEK...BUT SOME AGREEMENT WITH MOST MODELS WITH RESPECT TO A MORE ROBUST SHORT WAVE WITH RRQ UPPER JET REGION PASSING THROUGH TOWARD MID WEEK. COULD SEE ANOTHER ROUND OF A SOAKING RAIN WITH THE SURFACE FRONT AND H850 FRONT INTERACTING WITH THE UPPER JET. TEMPERATURES WILL BE ABOVE NORMAL THROUGH TUESDAY...AND WELL ABOVE NORMAL IN A STICKY AIR MASS SUNDAY ESPECIALLY IF THE CLOUDS CLEAR OUT. TEMPERATURES COOLING BACK TO NEAR NORMAL LATER NEXT WEEK. && .AVIATION...FOR 06Z TAF ISSUANCE ISSUED AT 1039 PM CDT FRI AUG 22 2014 MOIST AIR AND LIGHT WINDS WILL ALLOW FOR LOW CLOUDS AND AREAS OF DENSE FOG TO FORM OVER MUCH OF THE AREA TONIGHT. CONDITIONS WILL SLOWLY IMPROVE AFTER 13Z OR 14Z SATURDAY THOUGH CEILINGS COULD STAY IN THE IFR RANGE THROUGH MIDDAY. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......RDM
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
634 PM CDT FRI AUG 22 2014 UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE .SHORT TERM...TONIGHT AND SATURDAY ISSUED AT 215 PM CDT FRI AUG 22 2014 THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A WEAK AREA OF LOW PRESSURE SPINNING OVER WESTERN WISCONSIN EARLY THIS AFTERNOON. ALTHOUGH UPPER DIVERGENCE IN THE RIGHT REAR QUAD OF A JET STREAK HAS SHIFTED OFF TO THE EAST...CONVERGENCE NORTH OF A SURFACE WARM FRONT HAS GENERATED SCATTERED SHOWERS AND AN ISOLATED THUNDERSTORM OVER NORTH-CENTRAL WISCONSIN. ALSO OBSERVING RATHER BUBBLY LOOKING CU ALONG A COLD FRONTAL TYPE FEATURE MOVING INTO CENTRAL WISCONSIN THOUGH CONVERGENCE LOOKS QUITE WEAK...AND THE ONLY RETURNS ARE LOCATED OVER NORTHEAST IOWA. THE ATMOSPHERE IS GROWING UNSTABLE AHEAD OF THIS TROUGH/COOL FRONT WITH ML CAPES GROWING TO GREATER THAN 1000 J/KG...AND CIN FALLING RAPIDLY. THE NAM CREATES CONVECTION OVER CENTRAL WISCONSIN LATER THIS AFTERNOON...SO THIS IS SOMETHING TO KEEP AN EYE ON. INCLUDED A ISOLATED THUNDERSTORM MENTION FOR THE REST OF THE AFTERNOON OVER CENTRAL WISCONSIN. MEANWHILE...A LARGE UPPER TROUGH OVER THE PAC NW WILL SHIFT EAST CAUSING A WARM FRONT TO RE-ORGANIZE OVER THE PLAINS ON SATURDAY. PRECIP CHANCES AND FOG POTENTIAL REMAIN THE MAIN FORECAST CONCERNS. TONIGHT...MODELS ARE HAVING A TOUGH TIME LATCHING ON TO THAT LOW LEVEL CIRCULATION OVER WESTERN WISCONSIN. THE NAM AND TO A LESSER EXTEND THE GEM APPEAR TO HAVE A BETTER HANDLE ON THIS FEATURE THAN OTHER GUIDANCE. BUT CONFIDENCE WILL REMAIN LOW IN ANY CASE. BOTH THE NAM AND GEM SHOW THIS SURFACE LOW WEAKENING LATER THIS AFTERNOON OR THIS EVENING AND MORPHING INTO A SURFACE TROUGH OVER CENTRAL AND NORTH-CENTRAL WISCONSIN. THIS WILL KEEP AN ISOLATED TO SCATTERED THREAT OF SHOWERS AND STORMS INTO THE EVENING...AND POSSIBLY INTO THE OVERNIGHT HOURS TOO. THIS TROUGH WILL ALSO PROMOTE FOG DEVELOPMENT IN THESE AREAS TONIGHT AND THINK ANOTHER DENSE FOG ADVISORY WILL BE POSSIBLE FOR THE EARLY MORNING COMMUTE TOMORROW. LIGHT EASTERLY WINDS MAY ALSO ADVECT AREAS OF MARINE FOG INLAND INTO THE LAKESHORE COUNTIES TONIGHT. WARM AND MUGGY WITH LOWS IN THE 60S. SATURDAY...LOW PRESSURE WILL EMERGE INTO THE CENTRAL PLAINS AHEAD OF A DEEP PAC NW TROUGH. THE LOW LEVEL FLOW WILL REORGANIZE AND A WARM FRONT WILL LIFT INTO SOUTHWEST WISCONSIN IN THE AFTERNOON. THIS LOOKS TO BE A LITTLE SLOWER THAN YESTERDAYS RUNS AND WILL BACK OFF PRECIP CHANCES DURING THE MORNING. CHANCES IMPROVE DURING THE AFTERNOON OVER CENTRAL AND NORTH-CENTRAL WISCONSIN BUT AM SKEPTICAL SINCE THE FRONT WILL STILL BE WELL SOUTHWEST OF THE REGION AND MID-LEVEL RIDGING SHARPENS ALOFT. SO WILL MATCH WITH OTHER OFFICES BUT BRING UP CONCERN TO THE NEXT SHIFT. ONCE THE MORNING FOG AND LOW CLOUDS BURN OFF...CONTINUED WARM AND HUMID WITH HIGHS IN THE UPPER 70S TO LOWER 80S. .LONG TERM...SATURDAY NIGHT THROUGH FRIDAY ISSUED AT 215 PM CDT FRI AUG 22 2014 SATURDAY NIGHT INTO SUNDAY...THE UPPER RIDGE GETS NUDGED TO THE EAST A TAD WHILE A BROAD UPPER TROUGH APPROACHES FROM THE NORTHERN AND CENTRAL PLAINS. A DEEPENING LOW PRESSURE SYSTEM WILL LIFT NORTHWARD OVER THE NORTHERN PLAINS...AND LIFT A WARM FRONT NORTH OVER THE AREA. SOME PROGS GENERATE SOME CONVECTION WITH THIS FRONT SAT NIGHT INTO SUNDAY MORNING. CONVECTION MAY STRUGGLE TO DEVELOP DUE TO PROXIMITY TO THE UPPER RIDGE SO KEPT POPS ON THE LOW SIDE AND DECREASED THE DURATION OF THE CONVECTION MENTION. ISOLATED CONVECTION MAY LINGER SUNDAY MORNING ACROSS NORTHERN WISCONSIN...BUT BY NOON THE H850 BOUNDARY IS PROGGED TO BE WELL NORTH OF THE AREA. ANY PRECIPITATION CHANCES DURING THIS PERIOD WILL TEND TO BE FOCUSED TOWARD NORTHWEST WISCONSIN TOWARD THE BEST HEIGHT FALLS. SUNDAY NIGHT INTO MONDAY...NEXT CHANCE OF CONVECTION ALONG A TROUGH OR WEAKENING COLD FRONT. MOST MODEL RUNS DIMINISH THE PCPN AS IT WORKS INTO EASTERN WISCONSIN CLOSER TO THE UPPER RIDGE WHICH REMAINS OVER THE EASTERN GREAT LAKES AND MUCH OF THE EAST THIRD OF THE COUNTRY. THE BRUNT OF THE CONVECTION WILL LIKELY TRACK OVER NORTHWEST WISCONSIN AND ESPECIALLY OVER MINNESOTA NEAR THE SURFACE AND 850 LOW LIFTING NORTHEAST. MONDAY NIGHT...BROAD RRQ REGION OF THE UPPER JET FOCUSES THE CONVECTION OVER THE CENTRAL PLAINS WHILE WHILE WEAK HIGH PRESSURE BUILDS INTO THE REGION IN THE WAKE OF THE FROPA. THE GFS WAS THE ODD MODEL OUT WITH STALLING THE FRONT OVER THE AREA AND CONTINUING CONVECTION MONDAY NIGHT. MOST OF THE MODELS FOR THE REST OF NEXT WEEK...THE UPPER PATTERN SHIFTS FROM A SOUTHWEST FLOW ALOFT TO A NEARLY ZONAL FLOW LATE IN THE WEEK...BUT SOME AGREEMENT WITH MOST MODELS WITH RESPECT TO A MORE ROBUST SHORT WAVE WITH RRQ UPPER JET REGION PASSING THROUGH TOWARD MID WEEK. COULD SEE ANOTHER ROUND OF A SOAKING RAIN WITH THE SURFACE FRONT AND H850 FRONT INTERACTING WITH THE UPPER JET. TEMPERATURES WILL BE ABOVE NORMAL THROUGH TUESDAY...AND WELL ABOVE NORMAL IN A STICKY AIR MASS SUNDAY ESPECIALLY IF THE CLOUDS CLEAR OUT. TEMPERATURES COOLING BACK TO NEAR NORMAL LATER NEXT WEEK. && .AVIATION...FOR 00Z TAF ISSUANCE ISSUED AT 634 PM CDT FRI AUG 22 2014 MOIST AIR AND LIGHT WINDS WILL ALLOW FOR DENSE FOG TO FORM OVER MUCH OF THE AREA TONIGHT. MOST PLACES WILL HAVE IFR CONDITIONS BY MIDNIGHT. CONDITIONS WILL GRADUALLY IMPROVE AFTER 13Z OR 14Z SATURDAY. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......RDM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1149 PM CDT WED AUG 20 2014 .UPDATE... ISSUED AT 844 PM CDT WED AUG 20 2014 THE MAIN FOCUS CONTINUES TO BE ON THE CONVECTIVE TRENDS FOR THE OVERNIGHT PERIOD AS THE LOW LEVEL JET STRENGTHENS INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION. AN INITIAL BAND OF LIGHT RAIN SHOWERS HAS DEVELOPED ACROSS SOUTHWEST MINNESOTA AND NORTH CENTRAL IOWA ALONG THE LEADING/EASTERN EDGE OF THE LOW LEVEL MOISTURE TRANSPORT/WARM AIR ADVECTION WING. THESE SHOWERS HAVE BEEN VERY LIGHT AND ARE NOT EXPECTED TO STRENGTHEN IN INTENSITY THROUGH THE LATE EVENING HOURS. THE MAIN FOCUS IS FURTHER WEST UNDER THE MAIN CORRIDOR OF BETTER LOW LEVEL MOISTURE TRANSPORT THAT IS PUSHING UP INTO EASTERN SOUTH DAKOTA AND FAR SOUTHWESTERN MINNESOTA. CONVECTION IS STARTING TO DEVELOP ACROSS THIS CORRIDOR AND WILL INCREASE IN COVERAGE AND TRACK EAST OVERNIGHT. THE PAST FEW RUNS OF THE HRRR SEEM TO BE CATCHING UP TO THE CURRENT CONDITIONS AND SHOWING THIS TREND BETTER WITH THE MAIN BATCH OF RAIN/CONVECTION COMING THROUGH AROUND DAYBREAK TOMORROW MORNING. THEREFORE...HAVE BACKED OFF ON PRECIPITATION CHANCES THROUGH THIS EVENING AND FOCUSED THEM MORE ON THE EARLY MORNING HOURS ON THURSDAY. THE 21.00Z RAP SHOWS THE MAIN BELT OF ELEVATED INSTABILITY RUNNING FROM EASTERN IOWA INTO SOUTH CENTRAL SOUTH DAKOTA WITH A GRADUAL SHIFT NORTHWARD OF IT OVERNIGHT. THE TREND IS FOR THIS INSTABILITY TO CONTINUALLY WEAKEN AS THE NIGHT PROGRESSES WITH AROUND 1000 J/KG OF 0-3KM MUCAPE LEFT BY DAYBREAK. WITH THE INCREASING LIFT THANKS TO THE LLJ...STILL CAN NOT RULE OUT THAT A FEW OF THE STORMS COULD BECOME STRONGER...BUT THE THREAT OF WIDESPREAD STRONG TO SEVERE WEATHER APPEARS LOW. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 218 PM CDT WED AUG 20 2014 PRIMARY FORECAST CHALLENGE WILL BE SHOWER AND THUNDERSTORM TIMING AND COVERAGE TONIGHT THROUGH THURSDAY AND THE POTENTIAL FOR LOCALIZED FLOODING. CONVECTIVE CHANCES WILL CONTINUE TO BE A CONCERN FRIDAY THROUGH THE WEEKEND AS WELL. HIGH RESOLUTION MODELS BEGINNING TO CONVERGE ON A SOLUTION TONIGHT WHICH MATCHES WELL WITH SYNOPTIC/MESOSCALE SIGNALS IN GLOBAL MODEL SUITE. WILL USE A BLENDED MODEL SOLUTION WITH A SLIGHT PREFERENCE TOWARD THE ECMWF/ NAM AS THE GFS IS A BIT FASTER/FARTHER NORTH WITH FRONTAL PASSAGE TOMORROW. 20.20Z SURFACE ANALYSIS SHOWS A LOW PRESSURE CENTER ACROSS SOUTHWEST NE WITH ITS WARM FRONT DRAPED TO THE EAST ACROSS SOUTHERN NE INTO NORTHWEST MO. ACTUAL CONVECTION HAS BEEN FURTHER NORTH AND EAST ACROSS CENTRAL IA COINCIDENT WITH BEST MID-LEVEL WARM AIR ADVECTION...MOISTURE CONVERGENCE AND ISENTROPIC LIFT. SURFACE LOW IS PART OF A MUCH BROADER TROUGH THAT WILL SLOWLY LIFT NORTH AND EAST TONIGHT THROUGH THURSDAY PLACING THE SURFACE WARM FRONT ACROSS THE SOUTHERN FORECAST AREA BY 21.12Z. EXPECT A NORTHWEST TO SOUTHEAST ORIENTED LINE OF CONVECTION TO DEVELOP LATE THIS EVENING AHEAD OF THE FRONT AND MOVE NORTHEASTWARD ALIGNED ALONG OR JUST NORTH OF THE MISSISSIPPI RIVER VALLEY BY DAYBREAK THURSDAY. ELEVATED CAPE OVERNIGHT GENERALLY REMAINS LESS THAN 1000 J/KG...BUT 0 TO 6 KM BULK SHEAR INCREASES TO NEAR 40 KTS BY 21.12Z WITH IMPINGING 300 HPA JET STREAK. NOT EXPECTING WIDESPREAD SEVERE...BUT COULD SEE SOME ISOLATED LARGE HAIL OR DAMAGING WIND FROM THE STRONGEST STORMS. BIGGER CONCERN WILL BE HEAVY RAIN. EXPECT STRONG MID-LEVEL MOISTURE TRANSPORT WITH PRECIPITABLE WATER VALUES INCREASING TO NEAR 2.0 INCHES. SEE HYDROLOGY DISCUSSION FOR MORE DETAILS. 20.12Z ECMWF/NAM SUGGEST WARM FRONT MAY STALL THURSDAY AFTERNOON NEAR THE MISSISSIPPI RIVER VALLEY...RESULTING IN A PROLONGED PERIOD OF SHOWERS AND THUNDERSTORMS ACROSS WESTERN/CENTRAL WI. INCREASED POPS IN THESE AREAS THROUGH THE AFTERNOON AND LOWERED TEMPERATURES A HANDFUL OF DEGREES. SOUTH OF THE FRONT WILL WARM NICELY WITH TEMPERATURES RISING INTO THE UPPER 80S TO NEAR 90 DEGREES. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 218 PM CDT WED AUG 20 2014 MAIN SURFACE TROUGH WILL SWEEP ACROSS THE FORECAST AREA THURSDAY NIGHT...RESULTING IN DECREASING CONVECTION AND DRYING FROM WEST TO EAST. HOWEVER...REGION WILL REMAIN IN WARM MOIST AIR MASS RESULTING IN HIGH TEMPERATURES FRIDAY CLIMBING INTO THE MID TO UPPER 80S WITH DEW POINT TEMPERATURES INTO THE LOWER 70S. HARD TO PINPOINT A PROLONGED DRY PERIOD SATURDAY THROUGH WEDNESDAY. 500 HPA RIDGE BUILDS ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WITH ITS AXIS SLIDING SLOWLY TO THE EAST THROUGH THE WEEK RESULTING IN INCREASED SOUTHWEST FLOW ALOFT. A SERIES OF ILL- RESOLVED EMBEDDED SHORT WAVES COMBINED WITH A WAVERING SURFACE BOUNDARY WILL PROVIDE THE FOCUSING MECHANISMS FOR CONVECTION... BUT TIMING AND COVERAGE UNCERTAINTY ABOUNDS. THIS ALSO WRECKS HAVOC ON SEVERE POTENTIAL AND WILL NEED TO MONITOR SUBSEQUENT MODEL RUNS. WILL FOLLOW ALL BLEND POPS FOR NOW HIGHLIGHTING 20 TO 50 PERCENT CHANCES FOR MEASURABLE RAIN EACH PERIOD. TEMPERATURES THROUGH SUNDAY WILL REMAIN ON THE HIGH SIDE OF NORMAL WITH DAILY HIGHS IN THE MID TO UPPER 80S AND POSSIBLY EVEN BREACHING 90 DEGREES GIVEN 925 HPA TEMPERATURES RANGING FROM 22 TO 27 C. COULD SEE SOME RELIEF MONDAY/TUESDAY AS PRIMARY EASTERN PACIFIC TROUGH ATTEMPTS TO MAKE SOME HEADWAY INTO STUBBORN UPPER LEVEL RIDGE ACROSS THE GREAT LAKES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1149 PM CDT WED AUG 20 2014 CONFIDENCE CONTINUES TO DECLINE IN WHETHER ANY CONVECTION WILL OCCUR OVERNIGHT AS THE MAIN FOCUS CONTINUES TO BE WELL OFF TO THE WEST CLOSER TO LOW IN THE DAKOTAS. SOME VERY LIGHT RAIN SHOWERS HAVE BEEN SHOWING UP ACROSS SOUTH CENTRAL MINNESOTA AND NORTH CENTRAL IOWA BUT HAVE STRUGGLED TO MAKE IT EAST INTO THE REGION. HAVE BACKED OFF ON THE AMOUNT OF CONVECTION IN THE TAFS AND BROUGHT THE MAIN CHANCES IN AROUND OR AFTER DAYBREAK THURSDAY MORNING. CONFIDENCE IS FAIRLY LOW WITH HOW THINGS WILL EVOLVE BEYOND THAT INTO THURSDAY AFTERNOON AND EVENING...BUT IT SEEMS THAT THE FOCUS SHOULD BE TO THE NORTHEAST OF THE TAF SITES. && .HYDROLOGY... ISSUED AT 218 PM CDT WED AUG 20 2014 URBAN AND SMALL STREAM FLOODING AND/OR LOCALIZED FLASH FLOODING IS POSSIBLE TONIGHT THROUGH THURSDAY GIVEN MODEST FORCING IMPINGING ON A VERY MOIST AIR MASS. PRECIPITABLE WATER VALUES NEAR 2.0 INCHES ARE NEAR THE 99TH PERCENTILE OF THE CLIMATOLOGICAL NORMAL AT KMPX/KDVN. WARM CLOUD DEPTHS ARE ALSO VERY DEEP...WHICH SHOULD RESULT IN EFFICIENT WARM RAIN PROCESSES. EVEN WITH RECENT RAINFALL... REGIONAL SOILS ARE STILL RELATIVELY DRY AND SHOULD BE ABLE TO ABSORB HEAVY RAINFALL UNLESS RATES BEGIN TO EXCEED 2 INCHES/HOUR PER LATEST FLASH FLOOD GUIDANCE. CERTAINTY IN WIDESPREAD FLOODING RAINS NOT HIGH ENOUGH AT THIS TIME TO WARRANT A FLASH FLOOD WATCH...BUT FUTURE SHIFTS WILL NEED TO MONITOR THIS POTENTIAL. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE...HALBACH SHORT TERM...ROGERS LONG TERM....ROGERS AVIATION...HALBACH HYDROLOGY....ROGERS
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
818 PM MDT FRI AUG 22 2014 .UPDATE... ISSUED AT 807 PM MDT FRI AUG 22 2014 A PRONOUNCED MIDLVL SHORTWAVE CONTINUES TO LIFT NORTHEAST ACROSS CENTRAL CO THIS EVENING PER RECENT WATER VAPOR IMAGERY. REGIONAL RADAR MOSAIC SHOWS A BAND OF MODERATE RAIN AND EMBEDDED TSTMS HAS DEVELOPED OVER THE WESTERN NE PANHANDLE...LIKELY SUPPORTED BY A MESOSCALE VORTEX CURRENTLY IN THE VICINITY OF AKO. THIS AREA OF PCPN IS EXPECTED TO SHIFT NORTH AND EAST WITH TIME...SO HAVE THE CATEGORICAL POPS CONFINED TO AREAS ALONG AND SOUTHEAST OF A LINE FROM IBM TO SNY IN OUR CWA. PCPN INTENSITY SHOULD NOT BE PARTICULARLY HEAVY TONIGHT AS INSTABILITY WAS MITIGATED BY EXTENSIVE CLOUD COVER EARLIER TODAY. THINKING ANY THREAT FOR FLASH FLOODING IS RATHER LOW. NOT SURE HOW WIDESPREAD CONVECTION WILL BE ELSEWHERE...BUT ENOUGH MOISTURE IN MONSOONAL FLOW COMBINED WITH LARGER SCALE SUPPORT SUGGESTS A CONTINUED THREAT FOR ISOLATED TO SCATTERED SHOWERS FOR MOST OF THE NIGHT. FOG COULD BE A CONCERN TONIGHT...AND WEBCAMS HAVE ALREADY SHOWN THIS IN THE LARAMIE RANGE FOOTHILLS. DO NOT THINK THIS WILL LAST LONG AS ALL MODEL GUIDANCE SHOWS LLVL WINDS SHIFTING TO THE SOUTHWEST. FARTHER E...TRUE FOG IS UNLIKELY WITH MODERATE PCPN. OPTED NOT TO INCLUDE IN THE GRIDS ATTM BUT WILL CONTINUE TO MONITOR. ONLY OTHER CHANGE TO THE FCST WAS TO BUMP LOW TEMPS UP A FEW DEGREES WHERE THE MAIN PCPN BAND IS SETTING UP. DO NOT EXPECT MUCH FOR RADIATIONAL COOLING THERE. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 300 PM MDT FRI AUG 22 2014 PRETTY ACTIVE THE NEXT 24 TO 48 HOURS. TEMPERATURES AND POPS ARE THE FORECAST CHALLENGES FOR THE SHORT TERM. CURRENTLY...WATER VAPOR IMAGERY SHOWING A PRETTY PRONOUNCED WAVE IN THE MONSOONAL FLOW MOVING NORTH THIS AFTERNOON OUT OF NEW MEXICO INTO WEST CENTRAL COLORADO. MOSAIC RADAR SHOWING WIDESPREAD SHOWERS OVER CENTRAL COLORADO EARLY THIS AFTERNOON WITH A GENERAL NORTH NORTHEAST MOVEMENT ON THE CELLS. INFRARED RADAR SHOWING COOLING CLOUD TOPS WITH THIS WAVE AND WE ARE SEEING AN UPTICK IN LIGHTNING STRIKES ACROSS WESTERN COLORADO. UPPER LOW OVER IDAHO FAIRLY DYNAMIC AS WELL WITH NUMEROUS LIGHTNING STRIKES DEVELOPING. LATEST SPC MESOANALYSIS SHOWING A SLOW EROSION OF CIN OVER EXTREME SOUTHEAST WYOMING INTO THE KIMBALL AREA...WITH CAPE VALUES AROUND 1000 J/KG ABOVE. LOOKING AT CLOUD COVER OVERHEAD...IT IS PRETTY DENSE AND WE HAVE BEEN HARD PRESSED TO GET MUCH WARMING SO FAR TODAY. 1 PM TEMPERATURES HERE AT THE OFFICE AT 69 DEGREES WITH LOW TO MID 70S OUT IN THE PANHANDLE. FOR THIS EVENING...SHORTWAVE BEGINS TO MOVE INTO SOUTHEAST WYOMING SHORTLY AFTER 00Z WITH GUIDANCE INDICATING FAIRLY WIDESPREAD CONVECTION DEVELOPING AS THIS HAPPENS. THE 16Z HRRR FORECAST HAS CONVECTION DEVELOPING HERE AT CHEYENNE AROUND THE 22Z TIME FRAME...THEN EXPANDING ACROSS SOUTHERN WYOMING INTO THE PANHANDLE AFTER WARDS. BY 01Z...MOST LOCATIONS EAST OF THE LARAMIE RANGE SHOULD BE SEEING MEASURABLE RAINFALL WITH SCATTERED SHOWERS OUT WEST. NAM SOUNDINGS FOR THE PANHANDLE SHOWING PRETTY STRONG SHEAR OUT IN THE PANHANDLE THIS EVENING. LOOKING AT EASTERLY WINDS NEAR THE SURFACE OF 15 TO 20KTS WITH SOUTHWEST 40-45KTS AT 6KM. EVENING SHIFT WILL DEFINITELY NEED TO BE WATCHING FOR SEVERE THUNDERSTORMS. 0-3KM HELICITY FOR SIDNEY AT 386M2/S2 AT 00Z. GIVEN THE THICK CLOUD COVER THOUGH...CHANCES ARE DIMMING THAT WE WILL SEE SEVERE THUNDERSTORMS. SOMETHING ELSE FOR THIS AFTN/EVE...PRECIPITABLE WATER VALUES REALLY HIGH FOR THE PANHANDLE. SIDNEY SOUNDING SHOWING 1.42 INCHES...EXTENDING UP TO CHADRON AT 1.40 INCHES. FORECAST QPF REALLY HIGH FOR THE PANHANDLE AND EXTREME EASTERN WYOMING TONIGHT. GOOD NEWS IS FORECAST STORM MOTIONS ARE FROM THE SOUTHWEST AT 14-16KTS...SO THESE STORMS SHOULD BE MOVING FAIRLY FAST. WILL NEED TO WATCH THOUGH FOR TRAINING THUNDERSTORMS AND THERE COULD BE SOME FLASH FLOODING FOR SOME AREAS THIS EVENING. GFS AND ECMWF HAVE COME INTO DECENT AGREEMENT WITH THE UPSTREAM LOW ON THIS 12Z RUN. BOTH SHOWING THE CLOSED LOW MOVING PRETTY SLOW THROUGH NORTHERN WYOMING THROUGH THE DAY SATURDAY. MOST OF SATURDAY WILL SEE SHOWERS LASTING MOST OF THE DAY. WENT SIGNIFICANTLY HIGHER ON POPS OVER GUIDANCE. DO BELIEVE THE MID SHIFT WILL PROBABLY WANT TO GO HIGHER. FINALLY SATURDAY EVENING...THE UPPER LOW MOVES OFF INTO SOUTH DAKOTA WITH RAIN ENDING FROM WEST TO EAST. GOING TO BE PRETTY COOL WITH 700MB TEMPERATURES DOWN TO +6C SATURDAY NIGHT. SHOULD SEE WIDESPREAD 40S OUT WEST FOR LOWS...WITH LOW 50S EAST. CLOUD COVER COULD PROVIDE SLIGHTLY WARMER TEMPERATURES...WE WILL HAVE TO SEE AS THE EVENT GETS CLOSER. DID GO UNDER GUIDANCE FOR SUNDAY LOWS...ESPECIALLY OUT WEST WHERE CLOUD COVER WOULD BE LESS. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 335 PM MDT FRI AUG 22 2014 MEDIUM RANGE MODELS IN GOOD AGREEMENT THROUGH EARLY TUESDAY...BUT THEN SOLUTIONS BEGIN TO DIVERGE THROUGH WEDNESDAY...WITH POOR CONSISTENCY BETWEEN THE 12Z AND 00Z MODEL RUNS APPARENT INTO LATE NEXT WEEK. EARLY IN THE WEEK...MOIST SOUTHWEST FLOW AHEAD OF A POSITIVELY TILTED UPPER LEVEL TROUGH WILL MOVE ACROSS ACROSS THE IDAHO AND INTO WESTERN WYOMING. A WEAK BOUNDARY WILL DEVELOP AND DRIFT WESTWARD ALONG THE LARAMIE RANGE...WHICH WILL RESULT IN UPSLOPE FLOW AND ENHANCE LIFT ACROSS THE HIGH PLAINS. KEPT POP BETWEEN 35 TO 60 PERCENT ACROSS THE AREA WITH A GOOD CHANCE OF AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS. ALL MODELS SHOW THIS ACTIVITY LINGERING THROUGH MONDAY NIGHT AS WELL AS A WAVE OF LOW PRESSURE DEVELOPS ALONG THE BOUNDARY...WHICH WILL EVENTUALLY TRANSITION INTO A COLD FRONT. KEPT POP AROUND 50 PERCENT MONDAY NIGHT. WILL HAVE TO WATCH FOR STRONG TO SEVERE THUNDERSTORMS MONDAY EVENING WITH CAPE VALUES AROUND 1500 TO 2000 J/KG...HIGH PW/S...AND INSTABILITY. ECMWF STILL TRENDING SLOWER WITH THE UPPER LEVEL TROUGH COMPARED TO THE GFS. THE GEM HAS TRENDED TOWARDS THE ECMWF WHILE THE GFS PUSHES THE TROUGH THROUGH THE FORECAST AREA AS EARLY AS TUESDAY AFTERNOON. THE ECMWF AND GEM SHOW THE TROUGH AXIS MOVING ACROSS THE AREA LATE TUESDAY NIGHT AND EARLY WEDNESDAY. THE GEM AND ECMWF SOLUTIONS THEN DIVERGE WITH THE ECMWF SHOWING THE SYSTEM ATTEMPTING TO CLOSE OFF ON WEDNESDAY. EITHER WAY...EXPECT TUESDAY AND TUESDAY EVENING TO REMAIN UNSETTLED WITH COOLER THAN NORMAL TEMPERATURES AND A GOOD CHANCE OF WIDESPREAD RAINFALL. HIGHS MAY STRUGGLE TO REACH THE MID TO UPPER 60S ON TUESDAY AS 700MB TEMPERATURES LOWER BELOW 5C AFTER THE FRONT MOVES THROUGH THE AREA. LOW CONFIDENCE ON THE WEDNESDAY FORECAST DUE TO SIGNIFICANT MODEL DIFFERENCES. KEPT A SLIGHT CHANCE OF SHOWERS AND TSTORMS FOR NOW DUE TO TIMING DIFFERENCES...EVEN THOUGH THE ECMWF SOLUTION IS UNLIKELY TO OCCUR. MUCH DRIER AIR MOVES INTO THE REGION THURSDAY AND FRIDAY BASED ON CURRENT MODEL RUNS AS THE RIDGE AXIS REDEVELOPS WEST OF THE ROCKY MOUNTAINS AND DRIFTS EASTWARD. BASED ON 12Z MODELS...WARMER TEMPERATURES AND DRY CONDITIONS ARE EXPECTED NEXT WEEK. HOWEVER...THERE IS A LARGE CONTRAST BETWEEN THESE SOLUTIONS AND THE PREVIOUS 00Z SOLUTIONS FROM LAST NIGHT WHICH SHOW A PACIFIC SYSTEM MOVES INTO THE REGION WITH ANOTHER STRONG COLD FRONT ENTERING WYOMING BY LATE FRIDAY. KEPT TEMPERATURES NEAR NORMAL FOR NOW WITH POP BELOW 10 PERCENT. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY AFTERNOON) ISSUED AT 551 PM MDT FRI AUG 22 2014 A FEW ISOLATED THUNDERSTORMS WILL BE FOUND OVER SOUTHEAST WYOMING AND THE NEBRAKSA PANHANDLE THROUGH EARLY THIS EVENING...BUT WILL MOSTLY SEE RAIN SHOWERS. CONDITIONS WILL MAINLY REMAIN VFR THROUGH EARLY THIS EVENING BUT MVFR WILL OCCUR WITH SOME HEAVIER SHOWERS INTO THE SOUTHERN NEBRASKA PANHANDLE AND NEAR THE COLORADO AND WYOMING BORDER IN FAR SOUTHEAST WYOMING. INTO THE LATE NIGHT HOURS IFR CIGS WILL OCCUR OVER MUCH OF SOUTHEAST WYOMING AND NEBRASKA PANHANDLE...MAINLY ALONG AND EAST OF THE LARAMIE RANGE. FOG IS POSSIBLE LATE TONIGHT THROUGH MID MORNING SATURDAY WITH POCKETS OF LIFR. ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS EXPECTED FOR SATURDAY AFTERNOON AND EVENING. && .FIRE WEATHER... ISSUED AT 300 PM MDT FRI AUG 22 2014 MINIMAL FIRE WEATHER CONCERNS ACROSS THE AREA THROUGH THE NEXT FEW DAYS. UPPER LOW PRESSURE OVER IDAHO THIS AFTERNOON WILL BRING INCREASING MONSOONAL MOISTURE AND FAIRLY WIDESPREAD RAINFALL TO MUCH OF THE AREA TONIGHT INTO SATURDAY. BEST CHANCES FOR WETTING RAINS WILL BE ALONG AND EAST OF THE LARAMIE RANGE AS WELL AS THE SNOWY AND SIERRA MADRE RANGES. THE UPPER LOW WILL GRADUALLY MOVE INTO WESTERN SOUTH DAKOTA EARLY SUNDAY MORNING WITH RAINS ENDING FROM WEST TO EAST. COOLER TEMPERATURES BEHIND THE LOW WILL KEEP AFTERNOON HUMIDITIES FAIRLY HIGH WITH EXCELLENT OVERNIGHT && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ UPDATE...HAMMER SHORT TERM...CLAYCOMB LONG TERM...TJT AVIATION...SML FIRE WEATHER...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
601 PM MDT FRI AUG 22 2014 .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 300 PM MDT FRI AUG 22 2014 PRETTY ACTIVE THE NEXT 24 TO 48 HOURS. TEMPERATURES AND POPS ARE THE FORECAST CHALLENGES FOR THE SHORT TERM. CURRENTLY...WATER VAPOR IMAGERY SHOWING A PRETTY PRONOUNCED WAVE IN THE MONSOONAL FLOW MOVING NORTH THIS AFTERNOON OUT OF NEW MEXICO INTO WEST CENTRAL COLORADO. MOSAIC RADAR SHOWING WIDESPREAD SHOWERS OVER CENTRAL COLORADO EARLY THIS AFTERNOON WITH A GENERAL NORTH NORTHEAST MOVEMENT ON THE CELLS. INFRARED RADAR SHOWING COOLING CLOUD TOPS WITH THIS WAVE AND WE ARE SEEING AN UPTICK IN LIGHTNING STRIKES ACROSS WESTERN COLORADO. UPPER LOW OVER IDAHO FAIRLY DYNAMIC AS WELL WITH NUMEROUS LIGHTNING STRIKES DEVELOPING. LATEST SPC MESOANALYSIS SHOWING A SLOW EROSION OF CIN OVER EXTREME SOUTHEAST WYOMING INTO THE KIMBALL AREA...WITH CAPE VALUES AROUND 1000 J/KG ABOVE. LOOKING AT CLOUD COVER OVERHEAD...IT IS PRETTY DENSE AND WE HAVE BEEN HARD PRESSED TO GET MUCH WARMING SO FAR TODAY. 1 PM TEMPERATURES HERE AT THE OFFICE AT 69 DEGREES WITH LOW TO MID 70S OUT IN THE PANHANDLE. FOR THIS EVENING...SHORTWAVE BEGINS TO MOVE INTO SOUTHEAST WYOMING SHORTLY AFTER 00Z WITH GUIDANCE INDICATING FAIRLY WIDESPREAD CONVECTION DEVELOPING AS THIS HAPPENS. THE 16Z HRRR FORECAST HAS CONVECTION DEVELOPING HERE AT CHEYENNE AROUND THE 22Z TIME FRAME...THEN EXPANDING ACROSS SOUTHERN WYOMING INTO THE PANHANDLE AFTER WARDS. BY 01Z...MOST LOCATIONS EAST OF THE LARAMIE RANGE SHOULD BE SEEING MEASURABLE RAINFALL WITH SCATTERED SHOWERS OUT WEST. NAM SOUNDINGS FOR THE PANHANDLE SHOWING PRETTY STRONG SHEAR OUT IN THE PANHANDLE THIS EVENING. LOOKING AT EASTERLY WINDS NEAR THE SURFACE OF 15 TO 20KTS WITH SOUTHWEST 40-45KTS AT 6KM. EVENING SHIFT WILL DEFINITELY NEED TO BE WATCHING FOR SEVERE THUNDERSTORMS. 0-3KM HELICITY FOR SIDNEY AT 386M2/S2 AT 00Z. GIVEN THE THICK CLOUD COVER THOUGH...CHANCES ARE DIMMING THAT WE WILL SEE SEVERE THUNDERSTORMS. SOMETHING ELSE FOR THIS AFTN/EVE...PRECIPITABLE WATER VALUES REALLY HIGH FOR THE PANHANDLE. SIDNEY SOUNDING SHOWING 1.42 INCHES...EXTENDING UP TO CHADRON AT 1.40 INCHES. FORECAST QPF REALLY HIGH FOR THE PANHANDLE AND EXTREME EASTERN WYOMING TONIGHT. GOOD NEWS IS FORECAST STORM MOTIONS ARE FROM THE SOUTHWEST AT 14-16KTS...SO THESE STORMS SHOULD BE MOVING FAIRLY FAST. WILL NEED TO WATCH THOUGH FOR TRAINING THUNDERSTORMS AND THERE COULD BE SOME FLASH FLOODING FOR SOME AREAS THIS EVENING. GFS AND ECMWF HAVE COME INTO DECENT AGREEMENT WITH THE UPSTREAM LOW ON THIS 12Z RUN. BOTH SHOWING THE CLOSED LOW MOVING PRETTY SLOW THROUGH NORTHERN WYOMING THROUGH THE DAY SATURDAY. MOST OF SATURDAY WILL SEE SHOWERS LASTING MOST OF THE DAY. WENT SIGNIFICANTLY HIGHER ON POPS OVER GUIDANCE. DO BELIEVE THE MID SHIFT WILL PROBABLY WANT TO GO HIGHER. FINALLY SATURDAY EVENING...THE UPPER LOW MOVES OFF INTO SOUTH DAKOTA WITH RAIN ENDING FROM WEST TO EAST. GOING TO BE PRETTY COOL WITH 700MB TEMPERATURES DOWN TO +6C SATURDAY NIGHT. SHOULD SEE WIDESPREAD 40S OUT WEST FOR LOWS...WITH LOW 50S EAST. CLOUD COVER COULD PROVIDE SLIGHTLY WARMER TEMPERATURES...WE WILL HAVE TO SEE AS THE EVENT GETS CLOSER. DID GO UNDER GUIDANCE FOR SUNDAY LOWS...ESPECIALLY OUT WEST WHERE CLOUD COVER WOULD BE LESS. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 335 PM MDT FRI AUG 22 2014 MEDIUM RANGE MODELS IN GOOD AGREEMENT THROUGH EARLY TUESDAY...BUT THEN SOLUTIONS BEGIN TO DIVERGE THROUGH WEDNESDAY...WITH POOR CONSISTENCY BETWEEN THE 12Z AND 00Z MODEL RUNS APPARENT INTO LATE NEXT WEEK. EARLY IN THE WEEK...MOIST SOUTHWEST FLOW AHEAD OF A POSITIVELY TILTED UPPER LEVEL TROUGH WILL MOVE ACROSS ACROSS THE IDAHO AND INTO WESTERN WYOMING. A WEAK BOUNDARY WILL DEVELOP AND DRIFT WESTWARD ALONG THE LARAMIE RANGE...WHICH WILL RESULT IN UPSLOPE FLOW AND ENHANCE LIFT ACROSS THE HIGH PLAINS. KEPT POP BETWEEN 35 TO 60 PERCENT ACROSS THE AREA WITH A GOOD CHANCE OF AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS. ALL MODELS SHOW THIS ACTIVITY LINGERING THROUGH MONDAY NIGHT AS WELL AS A WAVE OF LOW PRESSURE DEVELOPS ALONG THE BOUNDARY...WHICH WILL EVENTUALLY TRANSITION INTO A COLD FRONT. KEPT POP AROUND 50 PERCENT MONDAY NIGHT. WILL HAVE TO WATCH FOR STRONG TO SEVERE THUNDERSTORMS MONDAY EVENING WITH CAPE VALUES AROUND 1500 TO 2000 J/KG...HIGH PW/S...AND INSTABILITY. ECMWF STILL TRENDING SLOWER WITH THE UPPER LEVEL TROUGH COMPARED TO THE GFS. THE GEM HAS TRENDED TOWARDS THE ECMWF WHILE THE GFS PUSHES THE TROUGH THROUGH THE FORECAST AREA AS EARLY AS TUESDAY AFTERNOON. THE ECMWF AND GEM SHOW THE TROUGH AXIS MOVING ACROSS THE AREA LATE TUESDAY NIGHT AND EARLY WEDNESDAY. THE GEM AND ECMWF SOLUTIONS THEN DIVERGE WITH THE ECMWF SHOWING THE SYSTEM ATTEMPTING TO CLOSE OFF ON WEDNESDAY. EITHER WAY...EXPECT TUESDAY AND TUESDAY EVENING TO REMAIN UNSETTLED WITH COOLER THAN NORMAL TEMPERATURES AND A GOOD CHANCE OF WIDESPREAD RAINFALL. HIGHS MAY STRUGGLE TO REACH THE MID TO UPPER 60S ON TUESDAY AS 700MB TEMPERATURES LOWER BELOW 5C AFTER THE FRONT MOVES THROUGH THE AREA. LOW CONFIDENCE ON THE WEDNESDAY FORECAST DUE TO SIGNIFICANT MODEL DIFFERENCES. KEPT A SLIGHT CHANCE OF SHOWERS AND TSTORMS FOR NOW DUE TO TIMING DIFFERENCES...EVEN THOUGH THE ECMWF SOLUTION IS UNLIKELY TO OCCUR. MUCH DRIER AIR MOVES INTO THE REGION THURSDAY AND FRIDAY BASED ON CURRENT MODEL RUNS AS THE RIDGE AXIS REDEVELOPS WEST OF THE ROCKY MOUNTAINS AND DRIFTS EASTWARD. BASED ON 12Z MODELS...WARMER TEMPERATURES AND DRY CONDITIONS ARE EXPECTED NEXT WEEK. HOWEVER...THERE IS A LARGE CONTRAST BETWEEN THESE SOLUTIONS AND THE PREVIOUS 00Z SOLUTIONS FROM LAST NIGHT WHICH SHOW A PACIFIC SYSTEM MOVES INTO THE REGION WITH ANOTHER STRONG COLD FRONT ENTERING WYOMING BY LATE FRIDAY. KEPT TEMPERATURES NEAR NORMAL FOR NOW WITH POP BELOW 10 PERCENT. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY AFTERNOON) ISSUED AT 551 PM MDT FRI AUG 22 2014 A FEW ISOLATED THUNDERSTORMS WILL BE FOUND OVER SOUTHEAST WYOMING AND THE NEBRAKSA PANHANDLE THROUGH EARLY THIS EVENING...BUT WILL MOSTLY SEE RAIN SHOWERS. CONDITIONS WILL MAINLY REMAIN VFR THROUGH EARLY THIS EVENING BUT MVFR WILL OCCUR WITH SOME HEAVIER SHOWERS INTO THE SOUTHERN NEBRASKA PANHANDLE AND NEAR THE COLORADO AND WYOMING BORDER IN FAR SOUTHEAST WYOMING. INTO THE LATE NIGHT HOURS IFR CIGS WILL OCCUR OVER MUCH OF SOUTHEAST WYOMING AND NEBRASKA PANHANDLE...MAINLY ALONG AND EAST OF THE LARAMIE RANGE. FOG IS POSSIBLE LATE TONIGHT THROUGH MID MORNING SATURDAY WITH POCKETS OF LIFR. ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS EXPECTED FOR SATURDAY AFTERNOON AND EVENING. && .FIRE WEATHER... ISSUED AT 300 PM MDT FRI AUG 22 2014 MINIMAL FIRE WEATHER CONCERNS ACROSS THE AREA THROUGH THE NEXT FEW DAYS. UPPER LOW PRESSURE OVER IDAHO THIS AFTERNOON WILL BRING INCREASING MONSOONAL MOISTURE AND FAIRLY WIDESPREAD RAINFALL TO MUCH OF THE AREA TONIGHT INTO SATURDAY. BEST CHANCES FOR WETTING RAINS WILL BE ALONG AND EAST OF THE LARAMIE RANGE AS WELL AS THE SNOWY AND SIERRA MADRE RANGES. THE UPPER LOW WILL GRADUALLY MOVE INTO WESTERN SOUTH DAKOTA EARLY SUNDAY MORNING WITH RAINS ENDING FROM WEST TO EAST. COOLER TEMPERATURES BEHIND THE LOW WILL KEEP AFTERNOON HUMIDITIES FAIRLY HIGH WITH EXCELLENT OVERNIGHT && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...CLAYCOMB LONG TERM...TJT AVIATION...SML FIRE WEATHER...CLAYCOMB
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1107 PM MDT WED AUG 20 2014 .UPDATE... ISSUED AT 846 PM MDT WED AUG 20 2014 MIDLVL MOISTURE PLUME CONTINUES TO STREAM NORTHWARD ACROSS THE CWA THIS EVE PER LATEST WATER VAPOR SAT. THIS HAS ALLOWED SHOWERS AND TSTMS TO PERSIST ACROSS PARTS OF THE AREA WELL INTO THE EVE. KCYS RADAR LOOP SHOWS TWO SEPARATE AREAS OF PCPN LIKELY IN ASSOCIATION WITH TWO DISTINCT SHORTWAVES EMANATING FROM THE UPPER LOW SPINNING OVER SOUTHERN CA. THESE AREAS ARE THE HIGHER TERRAIN OUT WEST OVER CARBON AND ALBANY COUNTIES...AND AREAS EAST OF I25 ALONG THE I80 CORRIDOR ACROSS WESTERN NE. HRRR TRENDS HAVE HINTED AT CONVECTION CONTINUING BEYOND 06Z OVER THE SOUTHERN PANHANDLE. ADDED POPS THRU 06Z WITH GOOD MOISTURE IN PLACE...BUT SHOWERS SHOULD BE DECREASING IN COVERAGE BY THEN. THE REST OF THE INHERITED FCST IS IN GOOD SHAPE THIS EVE. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 330 PM MDT WED AUG 20 2014 CURRENT KCYS RADAR LOOP SHOWS SHOWERS AND FEW THUNDER SHOWERS DEVELOPING OVER THE MOUNTAINS AND THE CHEYENNE RIDGE THIS AFTERNOON...AND SLOWLY MOVING EASTWARD. ACTIVITY HAS BEEN WEAK WITH ONLY A FEW ISOLATED LIGHTNING STRIKES. EXPECT THIS ACTIVITY TO CONTINUE THROUGH INTO LATE THIS AFTERNOON AND EARLY THIS EVENING WHILE DEVELOPING FURTHER EAST INTO THE HIGH PLAINS OF SOUTHEAST WYOMING. EXPECT ANY THUNDERSTORMS TO QUICKLY DIMINISH AROUND SUNSET. THUNDERSTORM COVERAGE WILL LIKELY BE LOWER ON THURSDAY ACROSS MOST OF THE FORECAST AREA AS WARMER AIR ALOFT MOVES INTO THE AREA AND 500MB HEIGHTS INCREASE THROUGH THE DAY. A COLD FRONT BOUNDARY WILL BECOME MORE NOTICEABLE FURTHER NORTH ACROSS MONTANA AND NORTHERN WYOMING AS IT SLOWLY DRIFTS SOUTHWARD THROUGH THE DAY. THEREFORE...EXPECT THE BEST COVERAGE OF SHOWERS AND THUNDERSTORMS TO BE ACROSS THE MOUNTAINS AND WELL NORTH OF I80. CAN NOT RULE OUT A THUNDER SHOWER OR TWO ALONG THE I80 CORRIDOR DURING THE EVENING HOURS. TEMPERATURES WILL REMAIN NEAR NORMAL AND GENERALLY IN THE UPPER 70S WEST OF THE LARAMIE RANGE AND LOW 80S TO LOW 90S ACROSS THE EASTERN PLAINS. THIS PERSISTENT WEATHER PATTERN WILL BEGIN TO CHANGE ON FRIDAY AND ESPECIALLY THIS WEEKEND. MODELS INDICATE A PRETTY STRONG COLD FRONT FOR THIS TIME OF THE YEAR PUSHING SOUTHWARD INTO SOUTHEAST WYOMING. THIS FRONT WILL STALL SOMETIME ON FRIDAY AND BE THE MAIN FOCUS FOR SCATTERED TO NUMEROUS SHOWERS AND TSTORMS AS AN UPPER LEVEL TROUGH FROM WESTERN CANADA MOVE SOUTH AND EVENTUALLY EASTWARD INTO IDAHO. LOWERED MAX AND MIN TEMPERATURES FRIDAY AND FRIDAY NIGHT AND INCREASED POP BETWEEN 25 TO 45 PERCENT ACROSS THE HIGH PLAINS...AND NEAR 70 PERCENT OVER THE MOUNTAINS. .LONG TERM...(SATURDAY THROUGH WEDNESDAY) ISSUED AT 330 PM MDT WED AUG 20 2014 BOTH THE GFS AND ECMWF BRING A SHORTWAVE THROUGH THE AREA IN SOUTHWEST WIND FLOW FRIDAY NIGHT INTO SATURDAY. ECMWF ROUGHLY 12 HOURS SLOWER THAN THE GFS...BUT BOTH ARE IN CLOSE AGREEMENT WITH MOVEMENT OF FIRST DISTURBANCE...THEN MOVING THE MAIN TROUGH THROUGH ON SATURDAY/SATURDAY NIGHT. JUST ABOUT EVERYONE SHOULD SEE SHOWERS/THUNDERSTORMS DURING THE DAY SATURDAY WITH BEST CHANCES FOR THE PANHANDLE SATURDAY NIGHT. MAIN SHORTWAVE THROUGH THE AREA BY SUNDAY...WITH MAINLY ISOLATED SHOWERS OVER THE MOUNTAINS. NEXT COLD FRONT LOOKS TO MOVE INTO THE AREA MONDAY AFTERNOON INTO TUESDAY. ECMWF A LITTLE COLDER THAN GFS IN 700MB TEMPERATURES...BUT NOT AS BAD AS A FEW DAYS AGO. PROBABLY NEED TO GO COLDER WITH THIS SETUP. DISCREPANCY MUCH GREATER ON TUESDAY WITH THE ECMWF FORECASTING 700MB TEMPERATURES OF +4 TO +6C AND GFS SHOWING +10 TO +12C. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY EVENING) ISSUED AT 1104 PM MDT WED AUG 20 2014 A FEW LINGERING SHOWERS AND THUNDERSTORMS AS OF 5Z WILL MOSTLY DIE OFF IN THE NEXT FEW HOURS. OUTSIDE ANY SHOWER OR THUNDERSTORM ACTIVITY...VFR WILL OCCUR THROUGH THE TAF PERIOD. WINDS WILL GENERALLY REMAIN LIGHT THROUGH THURSDAY BUT SOME GUSTS TO 25 MPH CAN BE EXPECTED THURSDAY AFTERNOON ALONG AND WEST OF THE LARAMIE RANGE. A FEW THUNDERSTORMS WILL BE POSSIBLE THURSDAY AFTERNOON AND EARLY EVENING. && .FIRE WEATHER... ISSUED AT 156 PM MDT WED AUG 20 2014 MINIMAL FIRE WEATHER CONCERNS INTO EARLY NEXT WEEK. SUBTROPICAL MOISTURE WILL REMAIN OVER THE AREA THROUGH THE WEEKEND WITH SHOWERS AND THUNDERSTORMS POSSIBLE EACH DAY ACROSS SOUTHEAST WYOMING AND WESTERN NEBRASKA. THERE IS A GOOD CHANCE OF WETTING RAINS BY FRIDAY AND THIS WEEKEND AS THUNDERSTORM COVERAGE WILL BE HIGHER. TEMPERATURES WILL TREND COOLER BY LATE THIS WEEK AND INTO THIS WEEKEND AS A STRONG COLD FRONT FOR THIS TIME OF THE YEAR MOVES INTO THE REGION LATE ON SATURDAY. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ UPDATE...HAMMER SHORT TERM...TJT LONG TERM...CLAYCOMB AVIATION...SML FIRE WEATHER...TJT
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
327 AM MDT SAT AUG 23 2014 .SHORT TERM...(TODAY THROUGH TONIGHT ) ISSUED AT 319 AM MDT SAT AUG 23 2014 A RATHER STG UPPER LEVEL TROUGH WILL MOVE ACROSS THE NRN ROCKIES THRU TONIGHT WITH COLORADO BEING ON THE SRN EDGE OF THE TROUGH. MEANWHILE AN UPPER LEVEL JET WILL REMAIN ACROSS NRN PORTIONS OF THE AREA THRU THIS EVENING WITH SOME POTENTIAL VORTICITY IN THE MID TO UPPER LEVELS. THUS SHOULD SEE A GOOD CHC OF SHOWERS AND TSTMS IN THE MTNS LATER THIS MORNING INTO THE AFTN HOURS. OVER NERN CO LOW LVL MOISTURE WILL MIX OUT SOME THRU THE DAY EXCEPT OVER THE FAR NERN PLAINS. CAPES WILL RANGE FM 500-1000 J/KG ALONG THE FRONT RANGE WHILE OVER THE FAR NERN PLAINS VALES WILL BE ABOVE 1500 J/KG. AS OUTFLOW BOUNDARIES FM CONVECTION OVER THE HIGHER TERRAIN MOVE ACROSS BY EARLY TO MID AFTN EXPECT SCT TSTMS TO DVLP ALONG THE FRONT RANGE AND THEN MOVE RATHER QUICKLY ACROSS THE PLAINS FM LATE AFTN INTO THE EARLY EVEING HOURS. WITH RATHER STG MID LVL FLOW A FEW STORMS COULD PRODUCE WIND GUSTS UP TO 60 MPH. OVER THE FAR NERN PLAINS WHERE CAPES WILL BE BETTER SOME MARGINAL LARGE HAIL COULD OCCUR AS WELL. AS FOR HIGHS WILL KEEP READINGS MOSTLY IN THE LOWER TO MID 80S ACROSS NERN CO. BY THIS EVENING AS DRIER AIR BEGINS TO SPREAD INTO THE MTNS PRECIP SHOULD GRADUALLY DECREASE OVER THE HIGHER TERRAIN. OVER NERN CO PCPN CHANCES SHOULD END BY EARLY EVENING ALONG THE FRONT RANGE AND THEN BY MIDNIGHT OVER THE FAR NERN CORNER. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 319 AM MDT SAT AUG 23 2014 SUNDAY AND SUNDAY NIGHT...THE FLOW ALOFT REMAIN SOUTHWESTERLY. ENOUGH SUBTROPICAL MOISTURE WILL BE AROUND VIA THE GFS/ECMWF MODELS TO KEEP A CHANCE OF TSTMS IN THE AFTN/EVNG. THE BEST CHC WL BE OVER THE MOUNTAINS. ON MONDAY...THE NEXT SYSTEM WILL APPROACH CO FM THE NORTHWEST...WITH A SOUTHWESTERLY FLOW AHEAD OF IT. THUNDERSTORMS WILL AGAIN DEVELOP OVER THE CWFA MONDAY AFTN/EVNG WITH THE TROUGH ITSELF STILL OVER SRN ID/NRN UT BY 12Z TUESDAY. THE ECMWF/NAM ARE SLOER THAN THE MORE PROGRESSIVE GFS WHICH MAINTAINS AN OPEN WAVE TROUGH...THE NAM DRIVES A CLOSED CIRCULATION INTO NORTHERN CA. THE ECMWF IS THE COMPROMISE MDL...IT CLOSES THE UPPER LOW BUT STILL SHIFTS IT EASTWARD ACROSS COLORADO...BUT SLOER...TUESDAY INTO WEDNESDAY. WL FOLLOW THIS PLAN FOR NOW AT BUMP THE POPS UPWARD FOR TUESDAY NIGHT AND WEDNESDAY. THURSDAY AND FRIDAY...WL CONTINUE WITH THE TREND OF DRIER AND WARMER WITH A RIDGE PROGGED TO BUILD OVER THE WESTERN U.S. && .AVIATION...(FOR THE TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 319 AM MDT SAT AUG 23 2014 TRICKY FCST FOR THIS MORNING DUE TO POTENTIAL FOG AS TEMP-DEWPOINT SPREADS ARE LOW AND WINDS ARE LIGHT. HRRR HAS BEEN ALTERNATING BETWEEN DENSE FOG AND NO DENSE FOG WITH EACH SUCCESSIVE RUN WHILE THE RAP HAS SHOWN NOTHING THE ENTIRE TIME. THE HRRR DOES SHOW SOME TYPE OF WK CYCLONE DEVELOPING NR DIA WITH WINDS BECOMING LIGHT NNW AROUND 12Z. IF THIS HAPPENS THEN POTENTIAL FOR DENSE FOG WOULD INCREASE IN THE 12Z-15Z TIME PERIOD. DUE TO UNCERTAINTY OF FCST WILL INTRODUCE A TEMPO GROUP FOR IFR CONDITIONS. FOR THIS AFTN OUTFLOW BOUNDARIES FM MTN CONVECTON WILL PUSH ACROSS BY 21Z WHICH MAY TRIGGER SCT TSTMS. WITH DECENT MID LVL FLOW THE STORMS WILL BE QUICK MOVING BUT COULD PRODUCE WIND GUSTS FM 40-50 MPH. ALSO WITH UPPER LEVEL JET OVERHEAD THIS IS SOME POSSIBILITY FOR STORM REGENERATION INTO THE EARLY EVENING HOURS THRU 02Z. BY MID EVENING THREAT OF STORMS SHOULD END. WINDS WILL BE ESE BY MIDDAY AND THEN SWITCH TO THE WNW BY 21Z AS INITIAL OUTFLOW BOUNDARIES MOVE ACROSS. BY EARLY EVENING WINDS WILL BE LIGHT NNW AND THEN TRANSITION TO DRAINAGE BY 06Z. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...RPK LONG TERM...COOPER AVIATION...RPK
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
155 AM EDT SAT AUG 23 2014 .SYNOPSIS... A BACK DOOR COLD FRONT WILL MOVE INTO AND THROUGH THE NORTHERN AND CENTRAL MIDLANDS SATURDAY...AND THEN SHIFT TOWARDS THE CSRA SUNDAY. THIS WILL LEAD TO A CHANCE OF THUNDERSTORMS ALONG AND AHEAD OF THE FRONT...WITH TEMPERATURES RETURNING TO MORE NORMAL LEVELS BEHIND IT. THE FRONT WILL LINGER SOUTH OF THE CSRA EARLY TO MID NEXT WEEK...LEADING TO GENERALLY FAIR WEATHER WITH NEAR NORMAL TEMPERATURES. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... WV LOOP SHOWS WEAK S/W MOVING SOUTHEASTWARD TOWARD THE NRN CWA/PEE DEE REGION. MODELS ALSO SHOW THIS S/W MOVING SOUTH/SOUTHEAST OVERNIGHT. 88D REGIONAL COMPOSITE SHOWS A CLUSTER OF SHRA/TSRA JUST NORTH OF CLT. HRRR INDICATES THAT SOME OF THIS ACTIVITY COULD SLIP INTO THE NRN MIDLANDS/PEE DEE OVER THE NEXT FEW HOURS. HAVE INCREASED POPS SLIGHTLY ACROSS LANCASTER...CHESTERFIELD...NRN KERSHAW AND NERN LEE COUNTY. OVERNIGHT LOWS IN THE LOW/MID 70S LOOK ON TRACK. OTHERWISE...SURFACE LOW PRESSURE ALONG THE VA COAST IS FORECAST TO MOVE SOUTHWARD OVERNIGHT INTO EASTERN NC. THIS WILL ALLOW A BACKDOOR COLD FRONT TO APPROACH THE NORTHERN MIDLANDS/PEE DEE AROUND DAYBREAK SATURDAY. KEPT OVERNIGHT LOWS NEAR CONSENSUS IN THE LOWER AND MIDDLE 70S. && .SHORT TERM /7 AM THIS MORNING THROUGH 6 PM SUNDAY/... MAIN ISSUE FOR SATURDAY AND INTO SUNDAY IS TIMING OF APPROACHING BACK DOOR FRONT. THINK PRE-FRONTAL TROUGH SETS UP ACROSS SOUTHERN CWA SATURDAY WITH FRONT IN EASTERN NORTH CAROLINA SHIFTING SOUTHWEST DURING SATURDAY EVENING. MOS POP GUIDANCE LOW BUT SREF AND MODEL QPF SUGGEST SCATTERED SHOWERS AND THUNDERSTORMS AHEAD AND ALONG FRONT AS AIR MASS MODERATELY UNSTABLE AND MOISTURE INCREASING...PRECIPITABLE WATER MAY RISE TO AROUND 2 INCHES. WARM MAX TEMPS STILL POSSIBLE SAT AHEAD OF THE FRONT...WITH WARMEST TEMPS FAVORING THE CSRA WHERE TEMPS COULD REACH 100 AGAIN. WITH NAM BEING SLIGHTLY FASTER THAN GFS WITH THE BACK DOOR FRONT...THE NAM MOS IS SLIGHTLY COOLER THAN THE GFS MOS FOR SAT MAX TEMP...ESPECIALLY NORTH AND CENTRAL. EVEN IF TEMPS NEAR 100 REACHED AGAIN SAT...GUIDANCE STILL SUGGESTS DEWPOINTS LOW ENOUGH TO PRECLUDE HEAT INDEX VALUES FROM REACHING OUR HEAT ADVISORY CRITERIA OF 110F. FRONT EXPECTED TO SHIFT SW THRU THE FA SAT NIGHT THRU SUN NIGHT. EXPECT CHANCE POPS NEAR AND JUST AHEAD OF THE FRONT...WITH COOLING TEMPS ALONG AND NORTH OF IT. SO...POPS SUN AFTERNOON FAVORING THE CSRA WHERE INSTABILITY/LOW LEVEL CONVERGENCE STRONGER. HIGH TEMPS SUNDAY SHOULD BE NOTICEABLY LESS BEHIND THE FRONT. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... MODELS IN GOOD AGREEMENT WITH MOVING THE FRONT SOUTH OF THE SAVANNAH RIVER WITH UPPER LEVEL RIDGE BUILDING IN FOR THE WEEK. WITH COOLER DRY AIR SETTLING IN WILL BRING SLIGHTLY BELOW NORMAL TEMPS. EXPECT MAX TEMPS 85 TO 90 EARLY TO MID WEEK RISING BACK INTO THE LOWER 90S LATER IN THE WEEK. OVERNIGHT MINS WILL BE 65 TO 70 RISING INTO THE LOWER 70S LATER IN THE WEEK. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS EXPECTED THROUGH THE PERIOD. SCATTERED CONVECTIVE DEBRIS FROM THUNDERSTORMS ALONG THE NC/SC LINE CONTINUE MOVING INTO THE TAF SITES. WITH THE WEAK FRONTAL BOUNDARY SLOWLY MOVING SOUTHWARD EXPECT INCREASING MID AND UPPER LEVEL CLOUDS OVERNIGHT...WHICH WILL WORK TO PREVENT FOG DEVELOPMENT. THE FRONT WILL REMAIN NORTH OF THE TAF SITES THROUGH THE PERIOD...WITH ISOLATED TO SCATTERED CONVECTION POSSIBLE DURING THE AFTERNOON AND EVENING HOURS. CONFIDENCE REMAINS LOW IN REGARD TO COVERAGE SO HAVE NOT INCLUDED MENTION OF CONVECTION IN TAFS ATTM. BEST CHANCE FOR CONVECTION WILL BE CAE/CUB AND NORTHWARD. WINDS THROUGH THE PERIOD WILL BE NORTHERLY AT 7 KNOTS OR LESS. EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG SUNDAY AND MONDAY. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS SUNDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1241 AM CDT SAT AUG 23 2014 .DISCUSSION... 259 PM CDT WE ARE LOOKING AT AN EXTENDED PERIOD OF MUGGY CONDITIONS OVER THE COMING WEEK WITH OFF AND ON CHANCES FOR SHOWERS AND THUNDERSTORMS. FORECAST FOCUS WAS TRYING TO PIN DOWN BETTER TIME FRAMES FOR THUNDERSTORM ACTIVITY. THIS IS COMPLICATED BY TRACKING VERY SUBTLE WAVES THAT MAKE ALL THE DIFFERENCE IN WHEN AND WHERE ADDITIONAL HEAVY RAIN WILL FALL. THE OVERALL PATTERN IS CHARACTERIZED BY A VERY BROAD UPPER RIDGE ACROSS THE MIDWEST WITH THE CENTER OF HIGH PRESSURE OVER THE ALABAMA/MISSISSIPPI WITH TROUGHING OFF THE EAST COAST...AN UPPER LEVEL TROUGH OVER THE PACIFIC NORTHWEST WITH A SHORTWAVE TROUGH FEEDING INTO THE BACK SIDE OF THE RIDGE IN ARIZONA. CLOSER TO HOME...WE ARE SOMEWHAT IN THE RING OF FIRE ON THE NORTH SIDE OF THE UPPER RIDGE AXIS WHERE SMALLER SCALE PERTURBATIONS CONTINUED TO ROTATE THROUGH THE AREA. THE UPPER LEVEL FLOW IS WEAK...AND WITH THE PATTERN AMPLIFIED...THE PATTERN DOES NOT LOOK TO CHANGE MUCH SOON. MEANWHILE...THE LOWER LEVEL BAROCLINIC ZONE REMAINS DRAPED JUST TO THE SOUTH OF OUR CWA THIS AFTERNOON. THERE IS A SURFACE BOUNDARY POSITIONED ALONG THE NORTHERN TIER OF OUR AREA...BUT THE SURFACE PATTERN IS A BIT MORE MUDDLED. WIDESPREAD DEWPOINTS IN THE 70S SUMS THINGS UP PRETTY WELL. IN THE NEAR TERM...CONVECTION FROM EARLIER HAS PUSHED SOUTH HAS CONTINUED TO WEAKEN AND PUSH SOUTHWEST AS LOW LEVEL FLOW IS TURNING NORTHWESTERLY...PUSHING BETTER MOISTURE TRANSPORT AND LIFT INTO THE LOW LEVEL BAROCLINIC ZONE TO THE SOUTH OF OUR CWA. WE CONTINUE TO WATCH SMALLER SCALE WAVES IN IOWA THAT WILL TRAVERSE THE RIDGE AS MOISTURE CONTINUES TO FEED FROM THE GULF INTO THE CENTER OF THE COUNTRY AND TOWARDS THE AREA. SOME HIGH RESOLUTION GUIDANCE IS HINTING AT SOME CONVECTION ALONG A LAKE BREEZE THIS AFTERNOON. THIS COULD BE AN AREA OF FOCUS AS A WEAK WAVE IN IOWA APPROACHES. IF ANYTHING FORMS...IT WOULD BE ISOLATED. CONFIDENCE ON THIS HAPPENING IS LOW AS ONLY A HANDFUL OF GUIDANCE MEMBERS ARE SHOWING THIS SOLUTION AND FEEL THAT IT WOULD ONLY BE ALONG SUBTLE CONVERGENCE BOUNDARIES. MUCH OF THE LARGER SCALE MODELS KEEP ANY PRECIPITATION WITH THIS WAVE ALONG OUR SOUTH AND WESTERN TIER OF COUNTIES WHERE WE KEEP THE HIGHEST POPS. EVEN THIS IS IN QUESTION AS THE MAIN FORCING IS HAVING A HARD TIME GETTING OUT OF IOWA WHERE MORE ORGANIZED THUNDERSTORM ACTIVITY IS ONGOING...BUT IT IS THESE AREAS THERE IS SOME 925 MB FLOW STILL INTO THE LOWER LEVEL BAROCLINIC ZONE THAT MAY AID IN SOME ENHANCEMENT TONIGHT. AREAS IN AN AROUND LIVINGSTON COUNTY HAD SOME PRETTY SIGNIFICANT RAINFALL..SO THIS WOULD BE AN AREA TO WATCH IF WE GET SOME ADDITIONAL DEVELOPMENT THIS EVENING AS THE GFS/EC SUGGEST. IF STUFF GETS GOING IT MAY LINGER INTO THE MORNING HOURS. ADMITTEDLY THE EVOLUTION OVER THE NEXT 12-18 HOURS IS LOWER THAN I WOULD LIKE. MODELS CONTINUE TO DIFFER WITH THE HANDLING OF THINGS ON SATURDAY AS WELL BUT STILL GENERALLY AGREE WITH THE BEST CHANCES SOUTH AND WEST OF THE MAIN METROPOLITAN AREA. FEEL LIKE THERE WILL BE MANY DRY PERIODS BUT THAT THUNDER IS POSSIBLE AND THEREFORE SOME DEGREE OF CHANCE POPS FOR NOW...WITH AREAS CLOSER TO THE LAKE HAVING SMALLER CHANCES. CONFIDENCE IN THIS PERIOD IS LOW-MEDIUM. SATURDAY NIGHT INTO SUNDAY...THE UPPER LEVEL RIDGE AXIS WILL AMPLIFY CAUSING THE MAIN MOISTURE TRANSPORT AXIS TO REMAIN OFF TO THE WEST. THIS WILL LARGELY KEEP MUCH OF NORTHEAST ILLINOIS AND NORTHWEST INDIANA UNDER DRY BUT MUGGY CONDITIONS. CONCERNS ON SUNDAY AND MONDAY WILL BE MORE SO ON THE HOT AND HUMID CONDITIONS WHERE HEAT INDICES WILL BE WELL INTO THE 90S...APPROACHING 100 IN THE SW CWA. SHORTWAVE ENERGY CURRENTLY OVER ARIZONA WILL MERGE WITH THE LARGE SCALE TROUGH OVER THE NORTHWEST AS THE TROUGH MOVES EASTWARD. THE RIDGE LOOKS TO HOLD AND SHUNT MOST OF THE INITIAL SHORTWAVE ENERGY WITH THE TROUGH NORTH AND WEST...WHICH WOULD SUGGEST THAT MONDAY CHANCES OF SHOWERS AND STORMS REMAINS LOWER THAN THE REMAINDER OF THE WEEK...THOUGH WE MAY GET GRAZED WITH IT SO WILL CONTINUE THE LOWER POPS FOR MONDAY. ON TUESDAY THE TROUGH/MOISTURE TRANSPORT AXIS GETS CLOSER. IT APPEARS THAT WEDNESDAY AND WEDNESDAY NIGHT WILL BE THE DAY WHEN WE TRANSITION OUT OF THE CURRENT AIR MASS. A COLD FRONT ASSOCIATED WITH THE UPPER TROUGH WILL BRING THE BEST CHANCE FOR ORGANIZED SHOWERS AND THUNDERSTORMS. WHILE PRECIPITABLE WATER VALUES IN THE EXTENDED TEND TO DROP SOME...WE ARE STILL LOOKING AT 2-3 STANDARD DEVIATIONS ABOVE NORMAL WHICH MEANS ANY PERIOD OF THUNDERSTORM ACTIVITY WILL POSE A THREAT FOR HEAVY RAINFALL. ON WEDNESDAY WE WILL ALSO HAVE BETTER WIND SHEAR...SO ADDITIONAL HAZARDS EXISTS INCLUDING THE POTENTIAL FOR STRONG/SEVERE WINDS AND HAIL. COOLER AND DRIER CONDITIONS ARE ON TAP FOR THE LATTER HALF OF THE WEEK WITH THURSDAY BEING A BIT BREEZY BEFORE HIGH PRESSURE MOVES OVERHEAD. KMD KMD && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * IFR CIGS POSSIBLE LATER TONIGHT THROUGH DAYBREAK. MVFR CIGS ALSO POSSIBLE. * EASTERLY WINDS EXPECTED TO BE LESS THAN 10 KT TODAY. * LOW CHANCES FOR ISOLD-SCT TSRA WITH BEST CHANCE THIS AFTERNOON...BUT MAY REMAIN TO THE WEST OF ORD/MDW. MDB //DISCUSSION...UPDATED 06Z... WEAK LOW LEVEL FLOW AND HUMID CONDITIONS CONTINUE ACROSS THE REGION TONIGHT WITH THE MAIN FORECAST CHALLENGE BEING POTENTIAL IFR CIGS AND VSBY. LATEST OB TRENDS SHOW A REDUCTION IN EARLIER LOWER CLOUD COVER AS AN EXTENSIVE SHIELD OF HIGHER CLOUD COVER WORKS IN. LIGHT NORTHEAST FLOW REMAINS NEAR THE LAKE MICHIGAN SHORELINE WITH WISCONSIN SHORELINE AREAS CONTINUING TO REPORT IFR CIGS/VSBY. HAVE SEEN LITTLE SOUTHWARD ADVANCEMENT OF THIS IFR INTO NE IL THUS FAR SO HAVE SLOWED THE ARRIVAL IN THE TAFS BY SEVERAL HOURS...THOUGH UGN IS NOW IFR. THE HIGHER CLOUD SHIELD MAY BE PREVENTING SIGNIFICANT EXPANSION FOR NOW. CONDITIONS REMAIN FAVORABLE FOR AN EXPANSION OF IFR BUT IT MAY BE THAT IFR ONLY DEVELOPS FOR A FEW HOURS CLOSER TO DAYLIGHT. BEYOND THAT EASTERLY WINDS OF 10 KT OR LESS ARE EXPECTED DURING THE DAY AND EASE UP THIS EVENING. DO NOT SEE MUCH IN THE WAY OF A CLEAR TRIGGER FOR ORGANIZED TSRA DEVELOPMENT BUT TSRA CHANCES ARE NOT ZERO. THE MOST FAVORED TIME SHOULD BE THIS AFTERNOON WITH MAX HEATING. WITH FLOW OFF THE LAKE ANY ACTIVITY MAY REMAIN WEST OF ORD/MDW/GYY AT LEAST INITIALLY BUT THEN DRIFT TO THE EAST. TSRA POTENTIAL AND CONFIDENCE IS TOO LOW TO INCLUDE ANY MENTION IN THE TAFS AT THIS POINT. MDB //ORD AND MDW CONFIDENCE...UPDATED 06Z... * LOW-MEDIUM CONFIDENCE THAT IFR CIGS DEVELOP OVERNIGHT. MEDIUM CONFIDENCE IN TIMING IF THEY DO. * HIGH CONFIDENCE IN WIND FORECAST. * MEDIUM CONFIDENCE THAT TSRA CHANCES ARE LOW. LOW-MEDIUM CONFIDENCE IN BEST TIMING BEING THIS AFTERNOON. MDB //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...SCHC TSRA IN THE AFTERNOON. MVFR CIGS/VSBY PSBL. MONDAY THROUGH WEDNESDAY...PERIODIC CHANCES FOR TSRA/SHRA WITH OCNL MVFR CIGS/VSBY. THURSDAY...SCHC SHRA. JEE && .MARINE... 246 PM CDT WINDS WILL REMAIN FAIRLY LIGHT AND FREQUENTLY CHANGING ACROSS THE LAKE OVER THE NEXT SEVERAL DAYS. A BROAD AREA OF LOW PRESSURE OVER THE PLAINS WILL CONSOLIDATE AND MOVE TO WESTERN ONTARIO SUNDAY. THIS WILL TURN WINDS SOUTHERLY AND INCREASE THEM SLIGHTLY TOWARD SUNDAY AFTERNOON INTO MONDAY. THE LOW WILL THEN TRACK NORTH OF THE LAKES AND PULL A FRONTAL BOUNDARY DOWN OVER LAKE MICHIGAN...LIKELY STALLING OUT OVER THE LAKE ALLOWING FOR VARIABLE WINDS TOWARD MIDWEEK. LENNING && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 1104 PM CDT Fri Aug 22 2014 .UPDATE... ISSUED AT 845 PM CDT FRI AUG 22 2014 Latest surface analysis indicating what`s left of an old outflow boundary from today`s convection located over parts of southeast Illinois this evening with some widely scattered showers along it. Further to the north, the synoptic frontal boundary was located over far southern Wisconsin with a weak cold front noted across central Iowa. Mid to upper 70 dew points were widespread from Iowa and Illinois south into the northern half of Missouri. 00z ILX sounding showing plenty of Cape for a parcel able to get above 800 mb later tonight with current Most Unstable Capes ranging from 2500-3500 J/kg. ILX Local objective analysis indicating a cap in place across the north and east, probably the result of the convection persisting into the early afternoon. Precipitable water values off the wall on the SPC mesoanalysis page with 2.2-2.3 inches analyzed this past hour from west central Illinois southeast into far southern Illinois. 0-6km shear values of only 15 to 20 kts compared to last night when we saw 30-35 kts. Now the main forecast concern, where and when convection breaks out again overnight. Models were definitely weaker with the low level jet with more of a split in the jet indicated with one area splitting off north into the central Plains with a much weaker jetlet forecast into southwest Missouri. Models do show some weak 850 mb moisture convergence/theta-e advection later tonight over parts of northeast Missouri into southeast Iowa. Latest HRRR model trending more towards what we saw with the 18z Nam-Wrf solution with the focus more with the aforementioned weak outflow boundary across south central and southeast Illinois later tonight. Any storms that do organize will bring the threat of heavy rain due to the weaker wind fields aloft and gusty winds, along with quite a lightning show. Storms that have been progressing slowly across parts of central Iowa late this afternoon and early this evening not showing a great deal of organization at this point as they were located under the building 500 mb ridge. Have made some minor adjustments to the grids to reflect the current trends this evening and will be sending out an updated ZFP to freshen up the wording for the overnight hours. Overall though, no significant changes made to the overnight convection threat across our area. && .SHORT TERM...(This evening through Saturday) ISSUED AT 256 PM CDT FRI AUG 22 2014 Main short-term concern is potential convective re-development tonight. As has been the case for the past few days, forecast models once again are having difficulty predicting the exact placement and track of nocturnal storm complex. Synoptic boundary remains draped well to the north from far northern Iowa to southern Lake Michigan: however, convection from earlier today was tied to an outflow boundary that dropped further southward into central Illinois. Think storms will develop along mesoscale boundaries later this evening as the low-level jet strengthens into the region. Radar trends are already showing scattered thunderstorms forming across central Iowa and these should develop/spread eastward into west-central Illinois later this evening. Mean flow would take the convection E/SE across the area overnight into Saturday morning. Based on radar trends and latest model data, have gone with high chance PoPs along/northeast of I-74, tapering down to just slight chances across the far S/SE CWA tonight. Given the very moist airmass as characterized by precipitable water values of over 2 inches, locally heavy rainfall will be possible late tonight into early Saturday morning. Convection will tend to move further eastward into Indiana and diminish toward midday Saturday, resulting in a mainly dry afternoon. Given increasing amounts of sunshine, high temperatures on Saturday will reach the upper 80s and lower 90s. These readings, combined with dewpoints in the middle 70s, will produce heat index values of 100 to 105F. Have therefore continued the current Heat Advisory with no areal changes. && .LONG TERM...(Saturday night through Friday) ISSUED AT 256 PM CDT FRI AUG 22 2014 Will continue the heat advisory for areas from Lincoln ssw through Monday afternoon for heat indices peaking from 100-107F and highest on Sunday and Monday afternoon over sw counties where several areas will be near 105F heat index. Highs in the low to mid 90s and dewpoints in the 70s to support these heat indices. Will need to keep alert to the possibility of expanding the heat advisory a bit further nne Sunday through Tuesday if heat indices reach closer to 105F. Strong upper level ridge building over the mid ms river valley Sun/Mon to cap atmosphere over central/sw IL and generally went dry with just ne IL have isolated convection. Upper level ridge to slowly break down during middle of next week allowing a frontal boundary to press se into IL. ECMWF is slower with front on Wed night and Thu. GFS is Wed afternoon into Wed night while GEM has front passing se into the IL river valley by overnight Wed night. With models trending slower past few days, favor the slower ECMWF and GEM models with frontal boundary pushing through central IL Wed night and southeast IL Thu. Have 20-30% chances of showers and thunderstorms returning Tue and Tue night, with best chances Wed/Thu. Still very warm and humid Wed with highs in the mid to upper 80s while southeast IL near 90F where afternoon heat indices peak in upper 90s to near 100F. More cooler air filters in on Thu with highs around 80F central IL and lower 80s southeast IL. Dewpoints slip into the mid to upper 50s during Thu night. Have dry conditions returning by Friday with more comfortable temperature and humidity levels, with highs next Friday in the upper 70s central IL and near 80F southeast IL with dewpoints in the upper 50s and lower 60s. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 1100 PM CDT FRI AUG 22 2014 Main forecast challenge remains timing and coverage of TSRA across our TAF locations overnight. Little overall change in thinking from previous set of TAFs with convection coverage still very much in doubt late this evening as the low level jet was positioned further to our west than the previous nights and other than a weak outflow boundary over southeast Illinois, the closest frontal boundary to us was located over far southern Wisconsin. Unless we see a dramatic increase in coverage of showers and storms over the next hour, will resort back to mentioning VCTS during the early morning hours into Saturday morning. Short term models not helping much as they have been coming up with a different solution with each run. Another concern will be with the potential for fog development in the 08z-13z time frame. Temp-dew point spreads, except for KPIA, were down to 3 degrees or less over the past hour and with copious amounts of moisture in the low levels, thanks in part to the moderate to locally heavy rain that fell across the area today, will introduce some MVFR vsbys at most sites. Whatever fog we see in the morning should lift by 13-14z with any lingering shower activity pulling out of the area by late morning with mainly VFR conditions expected for the rest of the forecast period. Surface winds will be light easterly at less than 5 kts tonight and then turn more into a southeast direction at less than 10 kts on Saturday. && .ILX WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY until 7 PM CDT Monday FOR ILZ042-047>054-056- 061>063-066>068-071>073. && $$ UPDATE...SMITH SHORT TERM...BARNES LONG TERM...07 AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
426 AM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 401 AM EDT SAT AUG 23 2014 WARM AND HUMID CONDITIONS WILL PERSIST FOR ONE MORE DAY BEFORE A BRIEF BREAK IN THE STICKY CONDITIONS ARRIVES TONIGHT INTO SUNDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND EVENING WITH CHANCES DIMINISHING TONIGHT. DRY CONDITIONS ARE EXPECTED UNTIL TUESDAY WHEN A COLD FRONT BEGINS TO APPROACH THE AREA. HIGHS WILL BE IN THE 80S WITH LOWS IN THE 60S THE NEXT COUPLE OF DAYS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 401 AM EDT SAT AUG 23 2014 SEVERAL SMALLER ITEMS TO TRY TO SORT OUT FOR THE FORECAST. FIRST OFF WILL BE COMBINATION OF MOIST LOW LEVEL AIR MASS AND MOSTLY CLEAR SKIES ALLOWING FOR STRATUS/FOG DEVELOPMENT ACROSS THE AREA. OBSERVATIONS HAVE BEEN SHOWING THIS ALREADY TAKING PLACE...WITH ISSUES EXPECTED TO PERSIST THROUGH AT LEAST 10 AM BEFORE SUFFICIENT MIXING OCCURS TO HELP BREAK THINGS UP. NEXT UP WILL BE ATTEMPT TO ADVECT IN SOMEWHAT DRIER AIR FROM THE NE AGAINST THE PERSISTENT BUT WEAK SW FLOW ACROSS MUCH OF THE WESTERN GREAT LAKES. A SUBTLE BOUNDARY WAS LOCATED FROM S LK MICHIGAN TO VICINITY OF FT WAYNE. THIS FEATURE...COMBINED WITH WHAT APPEARS TO BE A MID LEVEL DISTURBANCE OR SERIES OF GRAVITY WAVES...HELPED SPARK SMALL AREAS OF SLOW MOVING SHOWERS AND STORMS THAT HAVE SINCE DISSIPATED. LOCATIONS ALONG AND SW OF THIS BOUNDARY WILL SEE A CHANCE FOR HIT OR MISS SHOWERS/STORMS THIS AFTERNOON/EVE IF SUFFICIENT HEATING CAN TAKE PLACE. WARM AND HUMID CONDITIONS WILL REMAIN UNTIL THE NE FLOW CAN STRENGTHEN SLIGHTLY AS RIDGE INFLUENCE BRIEFLY RELAXES WITH DEWPOINTS DROPPING INTO THE MID 60S (LOW 60S NE). A FEW RUNS OF THE RUC TRY TO BRING THIS DRIER AIR A BIT FASTER IN NE SECTIONS THAT CURRENTLY DEPICTED. GIVEN WEAK NATURE OF SLOW...THINK SLOWER IS BETTER AT THIS POINT UNTIL DEGREE OF MIXING CAN BE DETERMINED. AS A RESULT...HIGHS SHOULD REACH THE MID 80S WITH HEAT INDICES NEAR OR JUST INTO THE 90S. NE FLOW WILL PUSH AXIS OF BEST PRECIPITATION POTENTIAL TO THE SW OF THE REGION DURING THE EVENING HOURS...LEADING TO WHAT SHOULD BE A PLEASANTLY DRY NIGHT AS LOWS DROP INTO THE MID 60S TO NEAR 70. HAVE KEPT A LINGERING SLGT CHC OF SHOWERS IN FAR SW AREAS EARLY EVENING BUT THEN REMOVED ALL MENTION OF PRECIPITATION AFTER 3Z. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 401 AM EDT SAT AUG 23 2014 STRONG SHRTWV MOVG THROUGH NRN NEVADA THIS MORNING EXPECTED TO LIFT SLOWLY NE THROUGH THE NRN HIGH PLAINS SUNDAY WITH DOWNSTREAM RIDGE MOVG EAST ACROSS OUR CWA. LACK OF FORCING AND A LITTLE DRIER AIR ADVECTING INTO OUR AREA IN THE H925-H85 LAYER DUE TO EASTERLY FLOW AROUND STRENGTHENING ANTICYCLONE OVER THE LWR GRTLKS SUGGESTS DRY CONDITIONS ACROSS OUR AREA. GOOD DEAL OF SUNSHINE SHOULD ALLOW MIXING UP TO NEAR H850 WHICH WOULD RESULT IN HIGHS IN THE M-U80S. NRN PLAINS SHRTWV EXPECTED TO MOVE EAST TO ONTARIO ON MONDAY. RIDGE OVER THE UPR GRTLKS WILL FLATTEN OUT IN RESPONSE BUT SHOULD HOLD STRONG IN OUR AREA KEEPING CONDITIONS DRY. TEMPS EXPECTED TO CONTINUE SLOW WARMING TREND AS WINDS VEER MORE SOUTHERLY WITH HIGHS IN THE U80S/L90S. ONTARIO SHRTWV EXPECTED TO SHEAR OUT AND LIFT ENE INTO QUEBEC TUE WITH TRAILING CDFNT SINKING SLOWLY SOUTH INTO OR CLOSE TO NRN PORTION OF OUR CWA BY WED MORNING. TSTMS SHOULD DEVELOP ALONG THE FRONT AND MAY PROPAGATE SE INTO UNSTABLE AIRMASS OVER OUR AREA... BUT CAPPING INVERSION MAKES THIS SCENARIO DOUBTFUL... SO JUST CONTD WITH LOW CHC POPS. TEMPS SHOULD REMAIN WELL ABOVE NORMAL WITH HIGHS AROUND 90 AND LOWS NEAR 70. MODEL SOLUTIONS DIVERGE SIGNIFICANTLY LATE WEEK WITH ECMWF/GEM SUGGESTING NEXT STRONG SHRTWV TO MOVE INTO MEAN WRN TROF WILL CUT-OFF OVER THE ROCKIES AND THEN MOVE SLOWLY EAST... WHILE GFS SUGGESTS A MORE PROGRESSIVE SCENARIO. IN EITHER CASE... LOW POPS STILL WARRANTED FOR WED-THU... WHILE GFS INDICATES COOLER/DRIER CONDITIONS WILL OVERSPREAD THE AREA BY FRIDAY. THIS SOLUTION IN BETTER AGREEMENT WITH GOING FCST AND GIVEN EXCESSIVE UNCERTAINTY WITH LARGE MODEL DIFFERENCES... STAYED CLOSE TO PREVIOUS FCST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1209 AM EDT SAT AUG 23 2014 STRATUS AND FOG WILL POSE A CONCERN INTO SATURDAY MORNING AT BOTH SITES AS MOIST BOUNDARY LAYER REMAINS IN PLACE FROM RECENT RAINFALL AND ABUNDANT MOISTURE IN THE AREA. A BOUNDARY WAS LOCATED IN THE VICINITY OF BOTH SITES BUT WAS MOST ACTIVE IN AND AROUND KFWA WHERE A SMALL AREA OF SHOWERS/STORMS WAS PERSISTING. THIS SHOULD DRIFT SOUTHEAST OVER THE NEXT HALF HOUR TO HOUR WITH ADDITIONAL ACTIVITY UPSTREAM THAT COULD DRIFT SE TOWARDS THE AIRPORT AGAIN. WILL MONITOR FOR AMENDMENTS. OTHERWISE NO SIGNIFICANT CHANGES PLANNED TO TAFS INTO SATURDAY NIGHT AS OVERALL PATTERN WILL CHANGE LITTLE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...FISHER SHORT TERM...FISHER LONG TERM...JT AVIATION...FISHER VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS DES MOINES IA
416 AM CDT SAT AUG 23 2014 .SHORT TERM /TODAY/... ISSUED AT 415 AM CDT SAT AUG 23 2014 YET ANOTHER ACTIVE OVERNIGHT/EARLY MORNING TODAY WITH A LARGE AREA OF THUNDERSTORMS MOVING ACROSS WEST/SOUTHWEST IOWA AT THE CURRENT HOUR. THIS ACTIVITY IS ASSOCIATED WITH THE NOSE OF THE NOCTURNAL LOW LEVEL JET AND A SURGE OF WARM AIR ADVECTION ALOFT COMING OUT OF THE SOUTHERN PLAINS. EXPECT THE STORMS TO MOVE SLOWLY ACROSS MUCH OF THE FORECAST AREA THIS MORNING AND HAVE INCLUDED HIGH POPS ACCORDINGLY. WHILE LOCALLY HEAVY RAINFALL WILL OCCUR...THE BAR FOR FLASH FLOODING IS SET HIGH DUE TO ANTECEDENT AND VEGETATIVE CONDITIONS. AS THE WARM AIR ADVECTION SURGE CONTINUES NORTHWARD AND THE JET WEAKENS AFTER SUNRISE...EXPECT THE SWATH OF THUNDERSTORMS TO SHIFT TOWARD THE NORTH AND NORTHEAST AND GRADUALLY DIMINISH...LIKELY ENDING IN OUR NORTHEASTERN COUNTIES IN THE EARLY AFTERNOON. MEANWHILE...BEHIND THIS PUSH HOTTER CONDITIONS WILL MOVE INTO PARTICULARLY SOUTH/SOUTHWEST IOWA IN THE AFTERNOON. HEATING WILL BE MITIGATED BY MORNING CONVECTIVE DEBRIS CLOUDS...SOUTHEASTERLY LOW LEVEL WIND TRAJECTORIES...AND PERSISTENTLY HIGH DEWPOINTS...BUT BELIEVE TEMPERATURES SHOULD STILL EXCEED YESTERDAYS LEVELS IN THESE AREAS WITH LOWER 90S TYPICAL. HEAT INDEX VALUES WILL LIKELY TOP OUT IN THE 100 TO 105 DEGREE RANGE ONCE AGAIN...JUST BELOW ADVISORY CRITERIA AND PRECLUDING A HEADLINE ISSUANCE AT THIS TIME. .LONG TERM /TONIGHT THROUGH FRIDAY/... ISSUED AT 415 AM CDT SAT AUG 23 2014 UPPER LOW MOVING ACROSS IDAHO THIS MORNING...WILL CONTINUE TO SHIFT EAST/NORTHEAST INTO WESTERN NORTH DAKOTA BY MID DAY SUNDAY. STRONG PV ANOMALY OVER COLORADO AND NEW MEXICO WILL LIFT QUICKLY NORTH AND BE INGESTED IN THE UPPER LOW OVERNIGHT. THIS WILL HELP PUSH THE FRONTAL BOUNDARY WILL NORTH OF THE STATE AND PLACING THE AREA INTO THE WARM SECTOR. MUCH DRIER MID LEVELS WILL HELP LOWER PWATS DOWN TO NEAR 1.25 INCHES...WHICH WILL HELP STABILIZE THE ATMOSPHERE. THE SUB TROPICAL HIGH WILL REMAIN ENTRENCHED OVER THE SOUTHEAST CONUS AND WILL KEEP SOUTHWEST FLOW OVER THE STATE THROUGH THE EARLY PORTION OF THE WEEK. TEMPERATURES SHOULD BE QUITE WARM ON SUNDAY WITH THE THERMAL RIDGE IN PLACE WITH HIGHS IN THE UPPER 80S TO MID 90S. ANOTHER STRONG UPPER LOW WILL MOVE THROUGH THE INTERMOUNTAIN WEST MID NEXT WEEK AND WILL HELP THE FRONTAL BOUNDARY DROP INTO IOWA AND BECOME NEARLY STATIONARY ONCE AGAIN. THIS WILL RESULT INTO SEVERAL CHANCES FOR THUNDERSTORMS TUESDAY AND WEDNESDAY WITH SOME SEVERE WEATHER AND THE POTENTIAL FOR LOCALLY HEAVY RAINFALL. THE UPPER LEVEL SYSTEM WILL EVENTUALLY PUSH THE SFC BOUNDARY TO THE EAST OF THE STATE THOUGH THIS MAY NOT OCCUR UNTIL THURSDAY. A NEARLY 20 DEGREE DIFFERENCE IN TEMPERATURES NORTH AND SOUTH OF THE BOUNDARY WHILE IT IS STALLED OVER THE AREA WITH 70S NORTH TO NEAR 90 SOUTH. COOLER FOR THE ENTIRE AREA BY FRIDAY. && .AVIATION...23/06Z ISSUED AT 1150 PM CDT FRI AUG 22 2014 DELAYED CONVECTION UNTIL PAST 12Z SATURDAY FOR ALL TAF SITES AS THE 23/00Z HOPWRF AND HRRR ARE IN GOOD AGREEMENT WITH CONVECTION SPREADING ACROSS SOUTH-CENTRAL IOWA WITH THE HRRR MORE WIDESPREAD FURTHER NORTH. HAVE MENTION OF VCTS AT FOD/DSM/OTM WITH A LITTLE HIGHER CONFIDENCE SITES WILL SEE STORMS. HAVE MVFR TO IFR VIS WRT TO FOG PAST 08Z TONIGHT. MIXING DEVELOPS LATE SATURDAY MORNING AND KEPT MENTION OF GUSTS THROUGH THE AFTERNOON HOURS. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...LEE LONG TERM...DONAVON AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1150 PM CDT FRI AUG 22 2014 ...UPDATED AVIATION DISCUSSION... .SHORT TERM /TONIGHT/... ISSUED AT 327 PM CDT FRI AUG 22 2014 THROUGH EARLY EVENING...STORMS HAVE FIRED IN TWO AREAS ACROSS CENTRAL IOWA. THE NORTHERN MOST LINE OF STORMS IS ASSOCIATED WITH A FRONTAL BOUNDARY THAT IS EVER SO SLOWLY MEANDERING SOUTH. FLOW IS WEAK AND THERE IS LITTLE CONVERGENCE AND NO SHEAR TO SPEAK OF SO THE STORMS WILL BECOME OUTFLOW DOMINANT AND SHOULD FALL APART BY 00-01Z. FURTHER SOUTH STORMS HAVE FIRED ALONG A MOISTURE AXIS. THIS AXIS WAS EVIDENT ON RADAR FOR MUCH OF THE DAY AND STORMS FIRED AFTER SUFFICIENT HEATING DESTABILIZED THE ATMOSPHERE. THESE STORMS WILL BE A BIT MORE ROBUST AND PRODUCE LOCALLY HEAVY RAINFALL...SOME STRONGER WIND GUSTS AND POSSIBLY SOME SMALL HAIL. AGAIN...THESE STORMS SHOULD MOVE EAST SOUTHEAST AND DIMINISH SHORTLY AFTER 00Z. THE REST OF EARLY TO MID EVENING SHOULD BE RELATIVELY QUIET THOUGH THINGS WILL FESTER THROUGH THE EVENING SO ISOLATED STORMS WILL STILL BE POSSIBLE. FOR THE REST OF TONIGHT...UPPER RIDGE OVER IOWA WILL GET PUSHED TO THE EAST WITH THE AXIS BY 12Z SAT INTO WESTERN IL BY A DEEPENING TROUGH OVER THE ROCKIES. SEVERAL WEAKER SHORTWAVES WILL EJECT OUT OF THE BASE OF THE TROUGH PUSHING ACROSS NORTHERN/WESTERN IOWA. IN ADDITION...THE FRONTAL BOUNDARY FROM A SURFACE LOW IN WESTERN KS WILL LIFT NORTHWARD AS THE SURFACE LOW SHIFT TO THE NORTHEAST. TO THE WEST OF IOWA THERE IS PRETTY IMPRESSIVE SHEAR AND STRONG THETA-E ADVECTION THAT WILL WORK INTO THE WEST AND NORTH AND GRADUALLY SHIFT MORE NORTH AND EAST. ONE AGAIN THE 4KM WRF HAD A DECENT HANDLE ON ALL OF THE CONVECTION OF THIS AFTERNOON AND TONIGHT SO I DID PUT SOME WEIGHT ON ITS SOLUTION FOR TONIGHT. STORMS SHOULD FIRE OUT WEST OF IOWA THIS AFTERNOON AND EVENING AND WILL PROBABLY MERGE INTO A CLUSTER OF STORMS THAT WILL THEN SHIFT INTO THE SOUTHWEST THIRD OF SO OF IOWA DURING THE OVERNIGHT. THERE MAY BE ISOLATED STORMS THROUGHOUT THE EVENING BUT THE MAIN PRECIP EVENT WILL OCCUR OVER THE SOUTHWEST BETWEEN 08Z-12Z BEFORE LIFTING NORTH. SOME STORMS WILL PRODUCE HEAVY RAINFALL BUT THERE MAY ALSO BE A COUPLE SEVERE STORMS AS WELL...MAINLY OVER THE FAR WESTERN PORTION OF THE CWA. IT WILL BE A MUGGY NIGHT WITH LOWS IN THE UPPER 60S OVER FAR NORTHERN IOWA AND 70S ELSEWHERE. DEWPOINTS WILL STAY IN THE UPPER 60S AND LOW TO MID 70S SO FOG WILL ONCE AGAIN DEVELOP...ESPECIALLY ACROSS THE NORTH. .LONG TERM /SATURDAY THROUGH FRIDAY/... ISSUED AT 327 PM CDT FRI AUG 22 2014 ACTIVE WX PATTERN EXPECTED AT LEAST THROUGH THE MIDDLE OF NEXT WEEK...WITH HOT AND HUMID SUMMERTIME WEATHER GIVING WAY TO FALL-LIKE WEATHER. MID/UPPER-LEVEL WIND SPEED MAX PLUNGING SOUTHWARD ALONG THE PAC COAST...ON THE WEST SIDE OF THE WESTERN U.S. TROF...WILL HELP FACILIATE ITS INTENSIFICATION BEFORE IT LIFTS OUT. IN RESPONSE...THE EASTERN U.S. RIDGE WILL AMPLIFY INTO THIS WEEKEND. A VORT MAX OVER THE SW U.S. WILL CONTINUE LIFTING NORTHEASTWARD. BY THE BEGINNING OF THE LONG TERM FCST PERIOD...LINGERING CONVECTION FROM OVERNIGHT WILL CONTINUE LIFTING NORTHWARD AHEAD OF A NORTHWARD-ADVANCING FRONTAL BOUNDARY. THE BOUNDARY IS EXPECTED TO BE IN THE VICINITY OF THE IA- MN BORDER...LIKELY JUST NORTH OF IT...BY LATE AFTERNOON SATURDAY. SOUTH OF THE BOUNDARY...TEMPERATURES WILL WARM MORE THAN WHAT WAS SEEN TODAY. PREVIOUS FCST DISCUSSION ACKNOWLEDGED MIXING ISSUES OVER THE PAST FEW DAYS AND ON SATURDAY...AND AGREE WITH THAT THINKING HOWEVER EXPECT IT TO BE MORE THAN WAS SEEN TODAY AS EVIDENCED BY STRONGER SURFACE WINDS THAN WAS SEEN TODAY. THUS HAVE NUDGED TEMPS UP A DEGREE OR TWO FROM THE GOING FORECAST FOR SATURDAY AFTERNOON. ADDITIONAL CONVECTION IS POSSIBLE SATURDAY NIGHT AS ANOTHER MID/UPPER-LEVEL DISTURBANCE MOVES THROUGH THE CENTRAL/NORTHERN PLAINS. BEST FORCING WILL REMAIN WEST AND NORTH OF THE CWA...AND HAVE PAINTED POPS AS SUCH. SUNDAY IS EXPECTED TO BE THE WARMEST DAY OF THE FCST PD WITH IA SOLIDLY WITHIN THE WARM SECTOR. NAM HAS CONTINUED TREND FROM PREVIOUS FCST OF BEING THE WARMEST WITH FCST HIGHS WELL INTO THE 90S. NAM IS SUGGESTING MORE MIXING ON SUNDAY THAN ON SATURDAY AS EVIDENCED BY LOWER DEWPOINTS AND STRONGER SURFACE WINDS. FOR NOW HAVE NOT CHANGED SUNDAY/S MAX TEMPS MUCH FROM PREVIOUS FCST. HEAT INDEX VALUES WILL BE AS HIGH AS AROUND 100F. HIGHER CHANCES OF SHRA/TSRA OCCUR SUNDAY NIGHT AS UPPER-LEVEL TROF TO OUR WEST EJECTS NORTHEASTWARD AND PUSHES A BOUNDARY INTO IA. MODELS SUGGEST THE BOUNDARY WILL HANG UP IN THE STATE...LIKELY MAKING IT AS FAR SOUTHEAST AS CENTRAL IA. INSTABILITY AND FORCING WILL BE PLENTIFUL ENOUGH TO RESULT IN AT LEAST SCATTERED SHRA/TSRA DURING THE NIGHT. AS THE UPPER LEVEL TROF EJECTS...ADDITIONAL UPSTREAM ENERGY WILL HELP ANOTHER TROF TO DEVELOP IN ITS PLACE OVER THE NORTHERN U.S. ROCKIES. WITH BOUNDARY REMAINING IN THE REGION...HAVE KEPT SLIGHT CHANCE POPS GOING INTO MONDAY. AFTER THIS POINT...THE MODEL SOLUTIONS DIVERGE LEADING TO INCREASING FORECAST UNCERTAINTY. GFS BRINGS THE SECOND TROF THROUGH FASTER THAN THE EURO. EXPECT THE BOUNDARY TO MOVE THROUGH THE CWA BY WEDNESDAY. HAVE INCREASED POPS BEGINNING TUESDAY AND KEPT THEM IN PLACE THROUGH LATE IN THE DAY ON WEDNESDAY. AFTER THE FRONTAL PASSAGE...A FEW DAYS OF FALL-LIKE WEATHER WILL PREVAIL WITH HIGH TEMPS ACROSS THE NORTHERN CWA POSSIBLY NOT LEAVING THE LOWER 70S ON WEDNESDAY. && .AVIATION...23/06Z ISSUED AT 1150 PM CDT FRI AUG 22 2014 DELAYED CONVECTION UNTIL PAST 12Z SATURDAY FOR ALL TAF SITES AS THE 23/00Z HOPWRF AND HRRR ARE IN GOOD AGREEMENT WITH CONVECTION SPREADING ACROSS SOUTH-CENTRAL IOWA WITH THE HRRR MORE WIDESPREAD FURTHER NORTH. HAVE MENTION OF VCTS AT FOD/DSM/OTM WITH A LITTLE HIGHER CONFIDENCE SITES WILL SEE STORMS. HAVE MVFR TO IFR VIS WRT TO FOG PAST 08Z TONIGHT. MIXING DEVELOPS LATE SATURDAY MORNING AND KEPT MENTION OF GUSTS THROUGH THE AFTERNOON HOURS. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...FAB LONG TERM...ZOGG AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
354 AM CDT SAT AUG 23 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 350 AM CDT SAT AUG 23 2014 WE HAVE BEEN WATCHING AN IMPRESSIVE THUNDERSTORM COMPLEX RACE NORTH ACROSS NEBRASKA OVERNIGHT IN ASSOCIATION WITH A SHORTWAVE ROTATING NNE AROUND THE BASE OF A DEEP TROUGH CENTERED OVER IDAHO. HOWEVER...DO NOT GET TOO EXCITED ABOUT THE PROSPECTS ABOUT ANYONE IN THE MPX CWA SEEING MUCH OF THIS PRECIP TODAY...AS THIS WAA PRECIP LOOKS TO LARGELY GO AROUND THE MPX CWA. MOST CAMS SHOW TWO CONCENTRATED AREAS THIS MORNING HEADING EAST ACROSS IOWA...WITH THE OTHER BATCH OF WIDESPREAD THUNDERSTORMS TO HEAD NORTH ACROSS THE DAKOTAS. THE IOWA AREA IS IN RESPONSE TO AIR GETTING FORCED UP OVER THE REMNANTS OF A COLD FRONT...WHICH AT 3 AM WAS LOCATED JUST SOUTH OF OMAHA TO THE QUAD CITIES...WHICH IS MORE OR LESS THE AXIS WHERE THE HRRR HAS A SWATH OF HIGHER QPF FALLING. THE DAKOTAS BULLSEYE IS RESPONSE THE NOSE OF A 40 KT ESE ORIENTED LLJ THAT WILL BE WORKING NORTH IN CONJUNCTION WITH THE STRONG SHORTWAVE CURRENTLY OVER CENTRAL NEB. WITH THAT SAID...ACTIVITY OUT THERE NOW LOOKS LIKE IT SHOULD HAVE ENOUGH MOMENTUM TO AT LEAST SNEAK UP TO AREAS SOUTH/WEST OF THE MN RIVER. OTHERWISE...FOR MUCH OF THE MPX AREA...THE BAND OF STORMS WE SEE COMING NORTH NOW WILL NOT DO MUCH MORE THAN BRING A BAND OF ALTOCU THROUGH THE AREA. FOR THIS AFTERNOON...ATTENTION TURNS TO THE SEVERE POTENTIAL OUT IN WRN MN. BY THE AFTERNOON...THE BROAD SFC CYCLONE CURRENTLY SPLAYED OUT ACROSS THE CENTRAL HIGH PLAINS WILL HAVE CONSOLIDATED INTO A 1000 MB LOW NEAR THE CENTRAL ND/SD BORDER. THIS WILL HELP PULL THE FRONT IN IOWA BACK NORTH AS A WARM...WITH IT PUSHING INTO SW MN AFTER 00Z. WILL HAVE TO WAIT A WHILE FOR SFC BASED CONVECTION TO FIRE GIVEN EXTENT OF RAIN/CLOUD COVER EXPECTED ACROSS THE DAKOTAS THIS MORNING..BUT EXPECT ENOUGH HEATING TO OCCUR THIS AFTERNOON TO ALLOW FOR STORMS TO DEVELOP NEAR THE SURGING WARM FRONT ALONG THE COTEAU IN SE SODAK AROUND 21Z...AS BOTH THE NMM/ARW SHOW. THIS ACTIVITY SHOULD THEN TRACK NNE...TOWARD WEST CENTRAL AND NORTHWEST MN DURING THE EVENING...AND IT IS THIS POTENTIAL ACTIVITY THAT GIVES US THE SLIGHT RISK FOR TODAY FROM THE SPC. CERTAINLY INSTABILITY AND SHEAR ARE ADEQUATE TO SUPPORT SURFACE BASED SUPERCELLS AND THEREFOR ALL MODES OF SEVERE WEATHER. HOWEVER...FOR AS FAR EAST AS MN...SHEAR VECTORS WILL BE MORE PARALLEL THAN PERPENDICULAR TO THE FORCING...WHICH WOULD FAVOR THE CONGEALING OF ACTIVITY INTO CLUSTERS/LINES...WHICH IS WHAT IS SEEN WITH NMM/ARW REFLECTIVITY FORECASTS. THIS WOULD FAVOR THE HIGHEST TORNADO THREAT BEING ACROSS THE DAKOTAS...WHERE STORMS ARE MORE LIKELY TO BE DISCRETE...WITH WRN MN DEALING MORE WITH A POTENTIAL WIND/HAIL THREAT. FROM THE FLOOD TREAT...PWATS WILL INCREASE BACK TO AROUND 1.75 INCHES...SO CERTAINLY WILL SEE HEAVY RAIN WITH THIS ACTIVITY. HOWEVER...CURRENT EXPECTATIONS ARE THAT ACTIVITY WILL BE PROGRESSIVE ENOUGH TO KEEP ANY CONCENTRATED SWATHS OF HIGH QPF DOWN IN THE 1-2 INCH RANGE AS OPPOSED TO BEING UP IN THE 3-6 INCH RANGE LIKE WE WERE SEEING LAST WEEK. FOR TONIGHT...BEST UPPER FORCING WILL BE STAYING NW OF THE MPX CWA...SO ACTIVITY THAT MOVES INTO WRN MN WILL HEAD FOR NW/NC MN...SO CUT BACK CONSIDERABLY ON POPS...KEEPING THE ERN 2/3RDS OR SO OF THE CWA DRY. MAY STILL BE TOO FAR EAST WITH POPS TONIGHT...BUT WE SHOULD SEE SOMEWHAT OF AN EWRD PUSH WITH ACTIVITY TONIGHT AS COLD POOLS GET GENERATED. EVEN IF IT DOES NOT RAIN...IT WILL BE A MUGGY NIGHT...AS LOWER 70 DEWPS COME UP WITH THE WARM FRONT. WILL LIKELY MAKE IT TOUGH FOR MUCH OF THE MN CWA TO DIP BELOW 70 SUNDAY MORNING...WHICH WILL HAVE IMPLICATIONS ON THE POTENTIAL NEED FOR ANY HEAT HEADLINES SUNDAY. NOT WORRIED ABOUT FOG TONIGHT EITHER...AS GRADIENT WILL REMAIN STRONG THROUGH THE NIGHT...SO WILL BE ANOTHER NIGHT LIKE TONIGHT WHERE WE JUST WATCH ANY STRATUS THAT SURVIVES THE DAY TODAY EXPAND AGAIN OVERNIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 350 AM CDT SAT AUG 23 2014 THERE IS DEFINITELY SOME SPREAD IN THE MODEL GUIDANCE AS WE HEAD THROUGH THE LATTER PORTION OF THE FORECAST... BUT THE GENERAL SCENARIO SUGGESTS A TRANSITION FOR WESTERN RIDGE/EASTERN TROUGH TO MORE OF A ZONAL PATTERN BY THE END OF THE WEEK. THIS SHOULD ALLOW FOR TEMPERATURES TO TREND FROM ABOVE NORMAL TO NEAR NORMAL AS THE WEEK UNFOLDS... WITH PCPN CHANCES BEING A BIT TOUGH TO PIN DOWN DEPENDING UPON WHERE THE MAIN BAROCLINIC ZONE SETS UP. GIVEN THE SPREAD IN DETERMINISTIC AND ENSEMBLE GUIDANCE... A CONSENSUS APPROACH IS THE MOST SENSIBLE COURSE OF ACTION... SO STUCK CLOSE TO A MULTI-MODEL BLEND. THE MAIN FORECAST ISSUES LOOK TO BE THE POTENTIAL FOR EXCESSIVE HEAT/HUMIDITY SUNDAY... THEN THE POSSIBILITY OF SIGNIFICANT PCPN OVER THE SOUTHERN PORTION OF THE AREA LATE MONDAY THROUGH WEDNESDAY AS THE FRONTAL BOUNDARY HANGS UP SOMEWHERE NEAR THE MINNESOTA/IOWA BORDER. SUNDAY STILL LOOKS TO HAVE THE POTENTIAL FOR VERY WARM TEMPERATURES ACROSS THE AREA... ALONG WITH HIGH DEWPOINTS. AT THIS POINT... APPARENT TEMPERATURE FORECASTS PEAK AROUND 100 OVER A PORTION OF THE AREA SUNDAY AFTERNOON WITH FORECAST HIGHS IN THE LOW 90S AND DEWPOINTS NEAR 70. WET BULB GLOBE TEMPERATURES JUMP INTO THE LOWER TO MIDDLE 80S AS WELL... ALSO INDICATING THE POTENTIAL FOR HEAT RELATED ISSUES FOR PEOPLE WHO MAY BE OUTDOORS ON SUNDAY. THERE WILL CERTAINLY BE A SIGNIFICANT NUMBER OF PEOPLE OUTDOORS IN THE METRO AREA ON SUNDAY WITH THE GREAT MINNESOTA GET TOGETHER IN FULL SWING... SO THE POSSIBILITY OF EXCESSIVE HEAT/HUMIDITY WILL NEED TO BE MONITORED IN SUBSEQUENT FORECASTS. AT THIS POINT... THERE IS STILL SOME UNCERTAINTY IN CLOUD COVER AND WHETHER WE/LL MIX AS WELL AS SOME GUIDANCE SUGGESTS AND/OR SEE MORE LOW LEVEL EVAPORATIVE COOLING THAN ANTICIPATED. SO... WILL HIGHLIGHT THE POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK AND OTHER SERVICES... BUT HOLD OFF ON ANY ACTUAL HEADLINES AT THIS POINT. PCPN CHANCES ON SUNDAY LOOK TO BE CONFINED TO THE WESTERN/NORTHERN PORTION OF THE AREA UNTIL LATE AFTERNOON AND/OR EVENING WHEN THE COLD FRONT FINALLY STARTS TO WORK ITS WAY EAST ACROSS THE AREA. AT THAT POINT... THE MAIN LARGE SCALE FORCING WILL BE TO OUR NORTH... SO PCPN MAY BE SCATTERED IN NATURE WITH MORE WIDESPREAD ACTIVITY WITH THE SHORTWAVE AND TRIPLE-POINT TO OUR NORTH AND THE SECONDARY WARM ADVECTION/INSTABILITY NOSE TO OUR SOUTH. DEEP LAYER SHEAR WILL BE BEST TO OUR NORTH... SO ANY SEVERE POTENTIAL LOOKS TO BE CAPE- DRIVEN WITH MAINLY MULTI-CELL WIND/HAIL STORMS BEING THE CONCERN. CHANCES FOR PCPN WILL PUSH EAST SUNDAY NIGHT WITH THE FRONT... THEN WE/LL SEE HIGH PRESSURE BUILD OVER MUCH OF THE AREA. HOWEVER... THE FRONTAL BOUNDARY LOOKS TO HANG UP TO OUR SOUTH/EAST MONDAY INTO WEDNESDAY... NECESSITATING THE INCLUSION OF POPS OVER MUCH OF THE AREA DURING THAT TIME FRAME... WITH BETTER CHANCES SOUTH AND LOW CHANCES NORTH. THE FAR SOUTHERN PORTION OF THE AREA HAS SOME POTENTIAL TO SEE SIGNIFICANT RAINFALL OVER THAT PERIOD OF TIME... BUT MUCH WILL DEPEND ON WHERE SUCCESSIVE ROUNDS OF SHRA/TSRA DECIDE TO TRACK... AND IT IS TOO EARLY TO GET A GOOD HANDLE ON THAT EVOLUTION. WE SHOULD SEE HIGH PRESSURE... SUBSIDENCE... AND DRIER AIR WORK INTO THE ENTIRE AREA FROM THE NORTHWEST WEDNESDAY NIGHT THROUGH THE REMAINDER OF THE FORECAST PERIOD... WITH DRY WEATHER PREDOMINATING. HOWEVER... THE 00Z ECMWF IS A BIT SLOWER IN SHOWING THIS EVOLUTION IN COMPARISON TO ITS PREVIOUS RUNS OR THE 00Z GFS... SO WE/LL NEED TO SEE HOW THINGS EVOLVE IN SUBSEQUENT FORECASTS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1047 PM CDT FRI AUG 22 2014 LINGERING MVFR CEILINGS OVER NERN PORTIONS OF THE COVERAGE AREA SLOWLY RECEDED NE THIS EVE BUT STILL HELD OVER KRNH WHILE THE REMAINING TAF SITES HELD IN VFR. BY LATE EVENING...THE PLENTIFUL LOW LEVEL MOISTURE AND LIGHT WINDS WILL AGAIN COMBINE TO PRODUCE IFR-OR-LOWER CONDITIONS...MAINLY DUE TO CEILINGS BUT ALSO POTENTIALLY FOG FOR THE USUAL SUSPECTS /A.K.A. KSTC...KRNH AND KEAU/. HAVE MAINTAINED THIS THINKING IN THE 00Z TAFS WITH THE WORST CONDITIONS MAINLY BETWEEN 08Z-14Z SAT. CONDS THEN LOOK TO SLOWLY IMPROVE THRU THE MRNG HOURS. ONE OTHER COMPLICATION IS THE POTENTIAL DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS/TSTMS OVER ERN SD/ERN NE/WRN IA THAT WILL SPREAD INTO SWRN MN BY AROUND DAYBREAK THRU LATE MRNG. THIS WOULD AFFECT KRWF-KAXN-KSTC LATE MRNG INTO THE EARLY AFTN. TOO EARLY ATTM TO DETERMINE FLIGHT COND DETERIORATION BUT WILL FOR NOW SHOW PREVAILING PRECIP AT THE WRN TAF SITES. BY LATE EVENING...THE PLENTIFUL LOW LEVEL MOISTURE AND LIGHT WINDS WILL AGAIN COMBINE TO PRODUCE IFR- OR-LOWER CONDITIONS...MAINLY DUE TO CEILINGS BUT ALSO POTENTIALLY FOG FOR THE USUAL SUSPECTS /A.K.A. KSTC...KRNH AND KEAU/. HAVE MAINTAINED THIS THINKING IN THE 00Z TAFS WITH THE WORST CONDITIONS MAINLY BETWEEN 08Z-14Z SAT. CONDS THEN LOOK TO SLOWLY IMPROVE THRU THE MRNG HOURS. ONE OTHER COMPLICATION IS THE POTENTIAL DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS/TSTMS OVER ERN SD/ERN NE/WRN IA THAT WILL SPREAD INTO SWRN MN BY AROUND DAYBREAK THRU LATE MRNG. THIS WOULD AFFECT KRWF-KAXN-KSTC LATE MRNG INTO THE EARLY AFTN. TOO EARLY ATTM TO DETERMINE FLIGHT COND DETERIORATION BUT WILL FOR NOW SHOW PREVAILING PRECIP AT THE WRN TAF SITES. KMSP...CONDS BOUNCED BETWEEN VFR AND MVFR FOR MUCH OF THE EVENING...FINALLY HOLDING AT VFR COMING INTO THE 06Z INITIALIZATION TIME. AM STILL LOOKING FOR CONDS TO DROP TO SUB-1700 FT CEILINGS LATER TONIGHT AND HOLDING THERE THRU THE EARLY MRNG HRS. IFR CONDS THEN SETTLE IN CLOSE TO DAYBREAK BUT AM NOT XPCTG MUCH OF A VSBY RESTRICTION FROM VFR...JUST INTO MVFR. THE IFR CIGS WILL THEN LIKELY LAST THRU LATE MRNG TO AROUND MIDDAY...WITH VFR CONDS EXPECTED TMRW AFTN. DEGRADED CONDS EXPECTED AGAIN SAT EVENING...BUT AM ONLY ADVERTISING MVFR CIGS ATTM AND THIS DEGRADATION MAY BE LATER THAN ADVERTISED. /OUTLOOK FOR KMSP/ SUN...VFR. MVFR/TSRA POSSIBLE EVENING/OVERNIGHT. WINDS S10G20 KTS. MON...VFR. WINDS W 5-10 KTS. TUE...MAINLY VFR. CHC MVFR IN TSRA. WINDS NE 5-10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM... AVIATION...JPC
AREA FORECAST DISCUSSION
NWS BILLINGS MT
1010 PM MDT FRI AUG 22 2014 .UPDATE... HAVE ISSUED A FLOOD WATCH FOR FAR SE MT AS ROUNDS OF HEAVY RAIN/EMBEDDED TSTMS EXPECTED TO LAST THROUGH THE NIGHT AND INTO SATURDAY...AS MONSOONAL ENERGY LIFTS UP THE HIGH PLAINS. A LONE SEVERE STORM IMPACTED SOUTHEAST MT A LITTLE WEST OF BROADUS EARLIER THIS EVENING. THIS HAS DISSIPATED AND CONVECTION IS FOCUSED IN SOUTHERN CARTER COUNTY NOW...AND IS NOT EXPECTED TO BECOME SEVERE. SHOWER ACTIVITY IS GRADUALLY BECOMING MORE WIDESPREAD ACROSS THE CWA IN RESPONSE TO INCREASING LARGE SCALE ASCENT WITH DEEP TROF DIGGING INTO IDAHO. LATEST H3 ANALYSIS SHOWS A VERY IMPRESSIVE 100 KT JET FROM OREGON INTO NEVADA...WITH STRONG DIFFLUENCE SHOWN ON SATELLITE IMAGERY FROM UTAH INTO SOUTHEAST IDAHO. ASCENT FROM THE UPPER LOW WILL ONLY INCREASE THROUGH THE NIGHT...AND IN FACT PER LATEST BLX VAD WINDS WE ARE SEEING EASTERLY UPSLOPE WINDS THROUGH 10KFT NOW. VERY IMPRESSIVE DYNAMICS FOR THE THIRD WEEK IN AUGUST. THERE REMAINS SOME UNCERTAINTY REGARDING TRACK OF MID LEVEL LOW BY EARLY SATURDAY MORNING WITH THE LATEST RAP SHOWING A WEAK 700MB LOW JUST NORTH OF BILLINGS...AND THIS IS NOT TOO DISSIMILAR TO THE NEW 00Z NAM...WITH THE GFS BEING A BIT FURTHER NORTH. SO AFTER A GOOD PERIOD OF RAIN TONIGHT WE MAY SEE THE HEAVIER PCPN SHIFT TO MAINLY OUR NORTH AND EAST PARTS FOR TOMORROW. THAT BEING SAID... RAP SHOWS 300MB LOW OVER SOUTHEAST IDAHO SATURDAY MORNING WHICH PUTS OUR AREA IN A VERY DIFFLUENT FLOW ALOFT...SO FEEL EVEN WITH SOME DEGREE OF LOW LEVEL DOWNSLOPING BY SATURDAY MORNING WE WILL STILL SEE ENOUGH ASCENT FOR SHOWERS IN THE BILLINGS AREA. INSTABILITY SHOULD REMAIN GREAT ENOUGH FOR EMBEDDED SCATTERED THUNDERSTORMS IN OUR EAST...OTHERWISE WE ARE LOOKING AT SHOWERS W/ ONLY ISOLD TSTMS THROUGH TOMORROW. FOR THE UPDATE HAVE RAISED POPS A BIT MORE ACROSS MUCH OF THE AREA TONIGHT AND SATURDAY. OVERALL FORECAST REMAINS ON TRACK. ITS GOING TO BE WET FOLKS. JKL && .SHORT TERM...VALID FOR SAT AND SUN... BROAD UPPER TROUGH OVER THE PACIFIC NW WILL CONTINUE TO PRODUCE AN UNUSUALLY COOL AND WET PERIOD ACROSS OUR REGION THE NEXT COUPLE OF DAYS. IF I WERE TO PICK A WETTEST PERIOD...IT WOULD BE TONIGHT INTO SATURDAY MORNING AS PLENTY OF LIFT IS PROGGED OVER OUR FORECAST AREA. ASSOCIATED JET DYNAMICS AND STRONG ISENTROPIC LIFT OUT IN FRONT OF THE UPPER TROUGH WILL LIKELY PRODUCE WIDESPREAD RAIN AND EMBEDDED THUNDER OVER THE AREA. SOME DISCRETE STRONG THUNDERSTORM CELLS ARE ALSO POSSIBLE FROM SHERIDAN TO CARTER COUNTY THIS EVENING AS EFFECTIVE SHEAR INCREASES ACROSS THIS AREA WITH A JET STREAK ALOFT. ONE OR TWO STRONG TO SEVERE STORMS ARE POSSIBLE IN THIS AREA DUE TO THE INCREASING POSSIBILITY OF SUSTAINED UPDRAFTS. LOOK FOR A VERY MOIST ATMOSPHERE WITH AREAS OF FOG AND LIGHT RAIN OVERNIGHT. SATURDAY...NEGATIVE TILT TROUGH WORKS INTO THE REGION FROM THE WEST AND MAY PRODUCE SOME STRONG TO SEVERE STORMS IN THE SE CORNER OF THE STATE DUE TO STRONG SHEAR AND INSTABILITY/LIFT. SEVERAL POCKETS OF LIFT WILL PRODUCE AREAS OF RAIN...MAINLY OVER THE NORTHERN AND EASTERN ZONES THROUGH SATURDAY. BY SATURDAY EVENING AS THE UPPER LOW MOVES OVER THERE IS SOME HINT OF DOWNSLOPE DRYING FROM HARLOWTON TO YELLOWSTONE COUNTY DUE TO NORTH/NORTHWEST FLOW WRAPPING AROUND THE LOW PRESSURE SYSTEM. THE ECMWF WANTS TO KEEP A CLOSED UPPER LOW OVER SE MONTANA WHILE THE GFS LIFTS THE SYSTEM NORTH. THE ECMWF VERSION IS MUCH WETTER THAN THE GFS. THERE IS NO REAL WAY TO DISCERN WHICH SOLUTION IS MOST ACCURATE AT THIS TIME ...THOUGH THE GFS HAS SUPPORT FROM THE NAM...AND GFS ENSEMBLE SPREADS ARE NOT THAT WIDE. THEREFORE...I HAVE BLENDED THE WET/DRY SOLUTIONS BUT LEANED A BIT MORE ON THE LESS WET GFS SOLUTION GOING INTO SUNDAY. LOOK FOR A BLUSTERY SATURDAY NIGHT AND SUNDAY WITH NORTH WINDS 15 TO 25 MPH COMBINED WITH THE RAINY CONDITIONS. BY SUNDAY NIGHT THE UPPER LOW IS TRACKING ACROSS NORTH DAKOTA WITH A MID LEVEL ZONAL FLOW SPREADING OVER MONTANA AND GENERALLY BRINGING MOST OF THE PRECIPITATION TO AN END OVER OUR FORECAST AREA. BT .LONG TERM...VALID FOR MON...TUE...WED...THU...FRI... MINIMAL UPDATES THIS AFTERNOON FOR THE INHERITED EXTENDED FORECAST...WITH MODELS IN GOOD AGREEMENT THROUGHOUT THE PERIOD. A SECONDARY LOBE OF THE BROAD UPPER TROF IS STILL VERY SLOW TO PUSH OFF TO THE EAST. THE TROF AXIS WILL BEGIN SLOW PROGRESSION EASTWARD MONDAY. THIS WILL BRING ANOTHER ROUND OF PRECIP THROUGH THE REGION BEGINNING MONDAY...AND LINGERING THROUGH MUCH OF TUESDAY. THE DYNAMICS FOR THIS SYSTEM APPEARS MUCH WEAKER...SO EXPECT SHOWERS AND THUNDERSTORMS TO BE MORE SCATTERED IN NATURE. THE SLOW MOVEMENT OF THE TROF WILL KEEP TEMPS WELL BELOW SEASONAL AVERAGE...WITH HIGHS IN THE LOW TO MID 70S EACH DAY. AN UPPER LEVEL RIDGE BEGINS BUILDING INTO THE REGION OVERNIGHT TUESDAY NIGHT...AND IS THEN FOLLOWED BY ZONAL FLOW DEVELOPING LATE THURSDAY. THEREFORE EXPECT WARMER AND DRIER CONDITIONS TO PREVAIL THROUGH THE REMAINDER OF THE EXTENDED PERIOD. TEMPERATURES WILL SLOWLY TREND UPWARD...BUT GENERALLY REMAIN AROUND SEASONAL AVERAGE. AAG && .AVIATION... SCATTERED SHOWERS...AND A FEW THUNDERSTORMS...WILL IMPACT ALL TERMINALS TONIGHT. EXPECTING MVFR AND IFR CONDITIONS WITH OCCASIONAL HEAVY RAINFALL THROUGH THE NIGHTTIME HOURS. CEILINGS WILL REMAIN LOW UNTIL THE DAYBREAK HOURS. SINGER && .PRELIMINARY POINT TEMP/POPS... SAT SUN MON TUE WED THU FRI ----------------------------------------------------------- BIL 056/063 049/065 048/071 050/075 053/082 057/087 061/085 +8/T 44/T 23/T 32/T 11/U 01/U 11/U LVM 051/060 045/064 042/070 044/075 048/083 051/086 051/084 +8/T 43/T 25/T 52/T 11/B 01/U 12/T HDN 057/068 050/066 046/074 050/077 051/083 055/088 059/088 98/T 55/T 13/T 32/T 11/U 01/U 11/U MLS 060/067 052/062 047/071 051/074 053/082 057/087 062/090 ++/T 86/T 22/T 22/T 11/U 11/U 11/B 4BQ 060/071 051/064 046/071 052/073 051/081 056/087 060/089 89/T 63/T 22/T 33/T 11/U 11/U 11/U BHK 056/066 050/061 046/069 047/071 048/078 053/083 059/086 9+/T 86/T 22/T 23/T 11/U 11/U 11/B SHR 055/070 047/065 044/073 048/074 048/081 051/087 055/089 76/T 53/T 13/T 43/T 11/U 01/U 11/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...FLOOD WATCH IN EFFECT THROUGH SATURDAY AFTERNOON FOR ZONES 32-33-36-37. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
409 AM CDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 408 AM CDT SAT AUG 23 2014 A SURFACE ANALYSIS AT 07Z INDICATED A FRONT DRAPED ACROSS SOUTHERN SOUTH DAKOTA WHILE ANOTHER WAS DRAPED FROM WEST CENTRAL INTO NORTHEAST KANSAS. A FAIRLY LARGE MCS WITH EMBEDDED MCVS CONTINUES TO LIFT FROM EASTERN AND NORTHERN NEBRASKA INTO SOUTH DAKOTA. MOST IF NOT ALL SHOWER ACTIVITY HAS ENDED FROM SOUTHWEST NEBRASKA INTO THE CENTRAL SANDHILLS. TEMPERATURES AND DEWPOINTS RANGING IN THE 60S ACROSS WRN AND NCTRL NEBR. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 408 AM CDT SAT AUG 23 2014 FOR TODAY... MODELS ARE IN FAIRLY GOOD AGREEMENT WITH A PV ANOMALY AND MID LEVEL DISTURBANCE LIFTING NORTHEAST FROM SOUTHERN UTAH CURRENTLY AND INTO NORTHEAST COLORADO BY 00Z THIS EVENING. ALONG WITH PEAK HEATING...THIS WILL PROVIDE AN INCREASE TO 30 POPS AFTER 21Z TODAY ACROSS THE NWRN HALF OF FA AND A SLIGHT CHC TO SOUTHEAST AREAS. A FAIRLY CLOUDY MORNING BASED ON RAP MODEL TIME SECTION AND LATEST SATELLITE IMAGERY. AFTERNOON CLEARING TO PARTLY CLOUDY EXPECTED FOR HIGHS FROM LOW 80S NORTHWEST TO UPPER 80S SOUTHWEST. FOR TONIGHT... THE ARW AND NMM MODELS FAVORED WHICH PERFORMED THE BEST WITH CURRENT SYSTEM EXITING THE AREA. BEST OVERALL PRECIPITATION CHANCES THIS EVENING WITH SYSTEM PASSAGE ARE 30-50 POPS WEST OF AN IML-ANW LINE AND 20-30 POPS FOR AREAS EAST. STORM MOTION WILL BE TO THE NORTHEAST AT 15 KTS. MUCH LESS RISK FOR LOCALLY HEAVY RAINFALL AS SOUNDINGS INDICATE WARM RAIN PROCESSES NOT OPERATING. NEVERTHELESS AREAS ACROSS THE WEST THIS EVENING MAY RECEIVE A TENTH TO QUARTER INCH OF NEW RAINFALL. POPS LOWERING TO 20 PERCENT AFTER MIDNIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 408 AM CDT SAT AUG 23 2014 AN ACTIVE WEATHER PATTERN WILL BE IN PLACE THROUGH THIS PERIOD WITH MULTIPLE CHANCES FOR RAIN AND COOLER TEMPERATURES EXPECTED FOR MUCH OF THE WEEK. THE UPPER LEVEL LOW NOW OVER IDAHO WILL CONTINUE TO IMPACT THE FORECAST AREA THROUGH THE FIRST PART OF THIS PERIOD. THE CURRENT FORECAST REMAINS DRY FOR SUNDAY AS THE MODELS SHOW A LACK OF MOISTURE ACROSS THE AREA. SEVERAL MODELS ARE INDICATING A NARROW BAND OF DEVELOPMENT MAINLY ACROSS CENTRAL NEBRASKA ALONG A COLD FRONT THAT LOOKS TO PUSH ACROSS THE FORECAST AREA DURING THE MORNING HOURS. THERE WILL BE SOME MID LEVEL SUPPORT AS THE UPPER LEVEL LOW LIFTS INTO NORTHWEST NORTH DAKOTA...DRAGGING WEAK SHORTWAVE ENERGY ACROSS THE CENTRAL PLAINS. WILL MONITOR FOR ANOTHER FORECAST CYCLE TO SEE IF THIS TREND CONTINUES AND IF SO...MAY NEED TO ADD SOME PRECIPITATION CHANCES FOR PART OF THE DAY SUNDAY. ALSO...A GOOD POOL OF COLD AIR WILL BE CIRCULATING AROUND THE SYSTEM...WITH MUCH COOLER AIR BEING DRAWN DOWN INTO NEBRASKA. BY 00Z TUESDAY THE MODELS ARE LIFTING THE SYSTEM FURTHER NORTH...ALLOWING WARM AIR ADVECTION TO BEGIN ACROSS THE SOUTH AND WESTERN PARTS OF THE AREA. WITH THE COOLER TEMPERATURES AND EXPECTING AT LEAST PARTIAL CLOUD COVER THE FORECAST HIGHS ARE NOW RANGING FROM THE MID 70S TO THE MID 80S. AN UPPER LEVEL LOW NOW MOVING INTO NORTHWEST CANADA OUT OF THE GULF OF ALASKA WILL DIG SOUTH INTO THE NORTHWEST PORTION OF THE CONUS BY MONDAY WHILE THE UPPER LOW TO THE NORTH PUSHES FURTHER NORTH AND EAST AWAY FROM THE AREA. THIS WILL KEEP THE CENTRAL PLAINS UNDER SOUTHWEST FLOW TO HELP BRING MOISTURE UP INTO THE AREA THROUGH MID-WEEK. FOR SUNDAY NIGHT...THE MODELS CONTINUE TO DEVELOP CONVECTION OVER NORTHEAST COLORADO...WHICH THEN SPREADS NORTHEAST INTO WESTERN NEBRASKA. THE AREA WILL BE IN THE FAVORED RIGHT ENTRANCE REGION OF THE JET AND WITH AN INCREASING LOW LEVEL JET /THOUGH NOT PARTICULARLY STRONG/ INTO THE EVENING THERE MIGHT BE ENOUGH FORCING TO KEEP THESE STORMS GOING OVERNIGHT INTO NEBRASKA SO MADE VERY LITTLE CHANGES TO ONGOING PRECIPITATION FORECAST. DURING THE DAY MONDAY...ATTEMPTED TO SHOW A TREND OF THIS ACTIVITY MOVING NORTHEAST AND THROUGH THE FORECAST AREA. MODELS SEEM TO BE SLOWING THE ADVANCEMENT OF THESE STORMS FROM PRIOR MODEL RUNS SO DON/T HAVE A HIGH DEGREE OF CONFIDENCE ON THE TIMING NOR PLACEMENT OF THESE STORM CHANCES. KEPT LIKELY CHANCES FOR RAIN FOR PORTIONS OF THE FORECAST AREA FOR MONDAY NIGHT. STILL LOOKS TO BE A SURFACE LOW SOMEWHERE OVER EASTERN COLORADO/WESTERN KANSAS WITH WARM FRONT EXTENDING INTO CENTRAL AND NORTHEAST NEBRASKA. THE MODELS ARE IN GOOD AGREEMENT WITH A WEAK SHORTWAVE TROUGH MOVING OUT OF THE FOUR CORNERS AND ACROSS THE CENTRAL PLAINS BY 12Z TUESDAY WHILE THE MAIN TROUGH REMAINS OFF TO THE WEST OVER IDAHO AND NEVADA. THE COMBINATION OF FORCING FROM THE SHORTWAVE TROUGH MOVING ACROSS THE AREA AND AN INCREASING LOW LEVEL JET BEING FOCUSED INTO WESTERN NEBRASKA FEEL THAT MONDAY NIGHT HAS THE HIGHEST CHANCES FOR RAINFALL. COULD BE ANOTHER DAY SIMILAR TO YESTERDAY WHERE THERE IS ENOUGH SHEAR AND INSTABILITY TO AT LEAST MENTION A THREAT FOR A FEW SEVERE STORMS...BUT THIS WILL DEPEND ON CONVECTION DURING THE DAY MONDAY AND WITH PRECIPITABLE WATER VALUES OVER 120 PERCENT OF NORMAL AND WARM CLOUD DEPTHS EXCEEDING 3500M STORMS SHOULD BE EFFICIENT RAIN MAKERS SO MAY BE DEALING WITH MORE OF A HEAVY RAIN THREAT. TUESDAY THROUGH FRIDAY...THE LONG RANGE MODELS BEGIN TO DIVERGE WITH HOW THEY HANDLE HOW THE TROUGH TO WEST BEHAVES. THE GFS QUICKLY PUSHES IT EAST THROUGH THE PLAINS AND INTO THE GREAT LAKES REGION BY THURSDAY WHILE THE ECMWF AND GEM ARE SLOWER AND DON/T MOVE IT OUT OF THE CENTRAL PLAINS UNTIL LATER IN THE WEEK. THIS WILL HAVE AN IMPACT ON THE SENSIBLE WEATHER AS THE SLOWER SOLUTION WOULD LINGER PRECIPITATION ACROSS THE AREA LONGER...AT LEAST THROUGH THURSDAY...WHILE THE GFS HAS A DRY FORECAST BY WEDNESDAY MORNING. HAVE NOT JUMPED ON THE SLOWER SOLUTION BUT DID LEAVE SOME SLIGHT CHANCES IN THE FORECAST THROUGH THURSDAY. WHAT IS FAIRLY CERTAIN EITHER WAY IS THAT TEMPERATURES WILL BE COOLER FOR THE WEEK. WITH PRECIPITATION AND CLOUD COVER...SOME DAYS MAY SEE HIGHS STRUGGLE TO GET INTO THE LOW AND MID 70S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1142 PM CDT FRI AUG 22 2014 TSTMS WILL CONTINUE LIFTING NORTH OVERNIGHT AND EXIT NRN NEB AROUND 12Z. A PERIOD OF MVFR CIGS MAY DEVELOP IN THE WAKE OF THESE STORMS BUT THE LATEST INDICATIONS ARE THESE CIGS WOULD NOT LAST MORE THAN AN HOUR OR TWO BEFORE IMPROVING TO VFR. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...ROBERG SHORT TERM...ROBERG LONG TERM...BROOKS AVIATION...CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1226 AM CDT SAT AUG 23 2014 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 256 PM CDT FRI AUG 22 2014 THE HIGHLIGHT OF THE SHORT TERM PERIOD WILL BE THE FACT WE ARE EXPECTING THUNDERSTORMS TODAY/TONIGHT. THERE STILL REMAINS SOME UNCERTAINTY FOR TIMING...LOCATION...AND OVERALL DEVELOPMENT. THE WARM FRONT TO OUR SOUTH...WHICH IS SITUATED OVER THE KANSAS/NEBRASKA BORDER...IS JUST MOSEYING ALONG TODAY AND HAS CAUSED SOME CONCERN FOR DEVELOPMENT. SHOWERS/STORMS SHOULD DEVELOP ALONG THIS BOUNDARY AS THE CAP BEGINS TO BREAK. SPC MESOSCALE ANALYSIS PAGE HAS US CAPPED UNTIL ABOUT 22-23Z. AT THIS TIME WE SHOULD SEE THE BEGINNING STAGES FOR INITIATION ALONG THE BOUNDARY TO OUR SOUTH. AMPLE INSTABILITY OF ABOUT 2000-3000 J/KG WILL BE IN PLACE...DUE TO A VERY MOIST BOUNDARY LAYER AND STEEP LAPSE RATES. MOST UNSTABLE CAPE COULD BE AS HIGH AS 4000 J/KG. BULK SHEAR 0-6 KM WILL BE AROUND 30 KNOTS...AND THIS IS NOT TOO IMPRESSIVE...HOWEVER...LOW LEVEL SHEAR WILL BE STRONG. EARLIER RUNS OF THE RAP INDICATED HELICITY VALUES NEAR 400 M2/S2 WOULD BE IN PLACE AROUND 23Z FOR WESTERN PORTIONS OF THE CWA. THESE VALUES WILL PUSH EASTWARD THROUGH THE AFTERNOON/EVENING. THESE LOW LEVEL HELICITY VALUES COUPLED WITH AMPLE INSTABILITY WILL POSE A THREAT FOR SOME ISOLATED TORNADOES...MAINLY FOR OUR NEBRASKA COUNTIES. WITH THAT BEING...WIND AND HAIL WILL BE THE MAIN THREATS TODAY/TONIGHT. THE BEST CHANCE FOR SEVERE WEATHER WILL BE ACROSS OUR NEBRASKA COUNTIES...BUT THE ENTIRE CWA DOES HAVE THE POTENTIAL FOR SEVERE WEATHER. I DO EXPECT THUNDERSTORM ACTIVITY TO KICK INTO GEAR AROUND 6 OR 7 PM...IF NOT SOONER. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 256 PM CDT FRI AUG 22 2014 VARIOUS RAIN CHANCES FOR THE WEEKEND AND IN TO THE FIRST PART OF THE WORK WEEK...ALONG WITH FLUCTUATING TEMPERATURES ARE PRIMARY FORECAST CONCERNS. WILL KEEP THIS FAIRLY SHORT DUE TO POSSIBLE SEVERE WEATHER DEVELOPING LATER THIS AFTERNOON. STARTING OUT SATURDAY EVENING IN THE MID/UPPER LEVELS...THERE SHOULD BE A LARGE AMPLITUDE TROUGH OVER THE ROCKIES WITH A CLOSED LOW SITUATED OVER EAST CENTRAL MONTANA...AS THE CURRENT SYSTEM OVER THE PACIFIC NW DRIFTS EASTWARD. THIS WILL PUSH THE RIDGE A LITTLE EAST AS WELL WITH THE AXIS STRETCHING FROM LAKE SUPERIOR TO MISSISSIPPI. THE BETTER FORCING WITH THE LOW PRESSURE SHOULD BE TO THE WEST AND NORTH OF OUR REGION. AT THE SURFACE...EXPECT A FRONTAL BOUNDARY TO BE TO OUR NORTH ACROSS SDAK AT 00Z AND THEN THIS WILL PUSH INTO OUR AREA BY SUNDAY MORNING. HAS NOT TAKEN A WHOLE LOT TO SET OFF CONVECTION THE PAST WEEK AND WHILE THE SET UP FOR SATURDAY NIGHT IS NOT AS GOOD AS TONIGHT...WILL PROBABLY STILL NEED SOME LOW POPS GIVEN APPROACHING WEAK COLD FRONT AND ANTICIPATED LOW LEVEL JET. PREVIOUS SHIFT AFD NOTED SOME HEAT BURST POTENTIAL WITH ANY THUNDERSTORMS THAT DO DEVELOP AND THIS SCENARIO STILL IN PLACE. WEATHER SHOULD BE QUIET DURING THE DAYTIME ON SUNDAY BEHIND THE COLD FRONT AND POSSIBLE SUNDAY NIGHT ALTHOUGH BOTH THE NAM AND GFS ARE DEVELOPING SOME PRECIPITATION TO THE WEST AND MOVING ACROSS THE CWA SUNDAY NIGHT. GFS APPEARS TO OVERDEVELOP A VORTICITY MAX ALTHOUGH DIFFICULT TO TOTALLY DISCOUNT WITH CYCLONIC FLOW IN UPPER LEVELS. MONDAY NIGHT AND TUESDAY NIGHT STILL LOOK ACTIVE AS YET ANOTHER HIGH AMPLITUDE TROUGH IS SLATED TO MOVE ACROSS THE ROCKIES AND INTO THE PLAINS. AT THE SURFACE AN EAST/WEST STATIONARY FRONT WILL HANG OUT OVER THE AREA RESULTING IN THE CLASSIC NIGHTTIME RAIN EVENTS. BY WEDNESDAY THE EXTENDED MODELS IN DECENT AGREEMENT IN PUSHING THE TROUGH EAST THROUGH THE CWA WITH RIDING THEN MOVING IN TO QUIET THINGS DOWN FOR THE REMAINDER OF THE WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1206 AM CDT SAT AUG 23 2014 SHOWERS AND THUNDERSTORMS WILL LINGER AT THE TERMINALS FOR ANOTHER HOUR OR SO THEN CONDITIONS WILL DRY OUT BY DAYBREAK. THERE MAY BE A BRIEF PERIOD OF REDUCED VSBYS IN BR DUE TO THE WET GROUND...BUT CONFIDENCE IS NOT HIGH FOR DEVELOPMENT OF FOG. LOOK FOR WINDS TO TRANSITION SOUTHERLY DURING THE DAY WITH WIND SPEEDS INCREASING AS THE SFC GRADIENT TIGHTENS. WIND GUSTS AROUND 25KTS ARE POSSIBLE. THERE IS AN OUTSIDE CHC FOR A TSTM BUT CHCS ARE NOT GREAT ENOUGH TO INCLUDE JUST YET. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...GUERRERO LONG TERM...EWALD AVIATION...FAY
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
146 AM EDT SAT AUG 23 2014 .SYNOPSIS... A COLD FRONT WILL SLIP SOUTHWARD INTO THE AREA SATURDAY. THIS FRONT WILL BRING A GOOD CHANCE FOR SHOWERS AND THUNDERSTORMS SATURDAY.. .BEFORE MUCH COOLER AND DRIER AIR FILTERS INTO THE REGION FOR SUNDAY. HIGH PRESSURE EXPANDING SOUTH FROM NEW ENGLAND WILL BRING COOL AND DRY WEATHER FOR THE FIRST HALF OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1:40 AM SATURDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSIONS FOLLOW: ALTHOUGH IT AFFECTED ONLY A SMALL PORTION OF OUR FORECAST AREA THIS EVENING`S STORMS WERE IMPRESSIVE. WIND GUSTS WERE MEASURED AS HIGH AS 47 MPH AT WRIGHTSVILLE BEACH...42 MPH AT THE WILMINGTON STATE PORT...AND 39 MPH AT THE WILMINGTON AIRPORT. DUAL-POL RADAR PRECIP ESTIMATIONS APPEAR TO BE RUNNING WITHIN WITHIN 5-10% OF ACTUAL GAUGE TOTALS WITH INDICATE 0.5 TO 2.5 INCH TOTALS ARE WIDESPREAD ACROSS NEW HANOVER AND EASTERN BRUNSWICK COUNTIES. NOW THAT THIS WAVE OF STORMS IS OFFSHORE...ATTENTION TURNS TO THE NEXT UPPER DISTURBANCE CURRENTLY MOVING SOUTHEAST ACROSS THE NC/VA BORDER. THE LAST FEW HRRR RUNS STILL TRY TO CRANK OUT SCATTERED CONVECTIVE SHOWERS AND T-STORMS WITH THIS FEATURE AS IT DIPS INTO THE COASTAL PLAIN VERY LATE TONIGHT. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... A HOT AIRMASS COVERS THE CAROLINAS THIS EVENING. 850 MB TEMPS AROUND +20C USUALLY EQUATES TO UPPER 90S INLAND FROM THE COAST AND TODAY`S HOT TEMPERATURES OF 97 IN FLORENCE AND LUMBERTON WERE EXPECTED. AN UPPER LEVEL RIDGE CENTERED OVER MISSISSIPPI IS PRODUCING A NORTHWEST UPPER WIND OVER THE CAROLINAS. A SERIES OF UPPER LEVEL DISTURBANCES EMBEDDED WITHIN IN THE 20-25 KT 700-500 MB FLOW ARE PRODUCING WAVES OF SHOWERS AND THUNDERSTORMS. ONE SUCH WAVE IS APPROACHING WILMINGTON FROM THE NORTH NOW AND SHOULD BE OFF THE COAST SOUTH OF CAPE FEAR BY LATE THIS EVENING. A SECOND DISTURBANCE NOW IN SOUTHWESTERN VIRGINIA AND EASTERN KENTUCKY WILL TAKE A MORE WESTWARD TRACK...REACHING THE SC PEE DEE AND INTERSTATE 95 CORRIDOR LATE TONIGHT. THIS IS ALSO WHEN A SYNOPTIC COLD FRONT WILL BEGIN TO EASE SOUTHWARD THROUGH SOUTHEASTERN NORTH CAROLINA...REACHING NORTHEASTERN SOUTH CAROLINA BY DAYBREAK SATURDAY. THUNDERSTORMS SHOULD CONTINUE TO BUILD SOUTHWARD INTO WILMINGTON OVER THE NEXT FEW HOURS...AND POPS HAVE BEEN RAISED TO 70 PERCENT FROM BURGAW SOUTH THROUGH WILMINGTON AND WRIGHTSVILLE BEACH. THE AIRMASS IS MODERATELY UNSTABLE (CAPE AROUND 2000 J/KG) AND THERE IS ENOUGH HUMIDITY NEAR THE LCL TO ALLOW SURFACE-BASED PARCELS TO REACH THEIR LFC AND KEEP ON GOING. ACTIVITY WILL BE MUCH MORE SPARSE IN COVERAGE WESTWARD ACROSS THE SOUTH CAROLINA COASTAL PLAIN WHERE ENVIRONMENTAL RELATIVE HUMIDITY NEAR THE LCL IS ONLY 50 TO 60%. OUTSIDE OF AREAS THAT RECEIVE THUNDERSTORMS...TEMPERATURES WILL FALL QUITE SLOWLY THIS EVENING IN THE HOT AIRMASS. NEAR THE COAST DEWPOINTS IN THE MID TO UPPER 70S WILL MAINTAIN HEAT INDICES IN THE AROUND 100 THROUGH 8 PM...AND IN THE 90S UP UNTIL ALMOST MIDNIGHT. LOWS SHOULD ONLY FALL INTO MID 70S FOR MOST ARES WITH SOME UPPER 70S NEAR THE BEACHES. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/... AS OF 300 PM FRIDAY...FEATURE OF INTEREST THIS WEEKEND IS A BACK DOOR COLD FRONT WHICH WILL DROP ACROSS THE AREA FROM NE TO SW ON SATURDAY. THIS FRONT WILL BE DRIVEN BY AN AMPLIFYING 5H PATTERN...WITH A STRONG RIDGE GETTING SQUEEZED NORTH ACROSS THE MIDDLE OF THE COUNTRY BETWEEN TROUGHS ON BOTH COASTS. IT IS THIS EASTERN TROUGH DIVING SW THROUGH THE WKND THAT PUSHES THE BACK DOOR FRONT INTO...AND THROUGH...THE CWA SATURDAY. ALTHOUGH THE SURFACE FRONT CROSSES SATURDAY...STRONG CAA LAGS ABOUT 18 HRS BEHIND...AND THUS SATURDAY WILL AGAIN BE A WARM DAY LOCALLY. HOWEVER...INCREASED CLOUDINESS...LOWERED THICKNESSES...AND SHOWERS/STORMS WILL KEEP TEMPS MUCH COOLER THAN THE PAST FEW DAYS...WITH HIGHS RISING TO AROUND 90 IN THE FAR NORTH...MID 90S IN THE SOUTHERN PEE DEE. WHILE FORCING IS NOT STRONG WITH THE FRONT...AND A DIVING UPPER JET WILL ACTUALLY PUT THE REGION BENEATH THE RFQ...AN UNFAVORABLE POSITION FOR UPPER SUPPORT...STILL EXPECT CLIMO POP FOR SCT SHOWERS AND TSTMS THANKS TO PWATS NEAR 2 INCHES AND STRONG SURFACE CONVERGENCE INTO AN UNSTABLE ENVIRONMENT. ALTHOUGH COOL ADVECTION WILL BEGIN OVERNIGHT...LOWS WILL REMAIN ABOVE NORMAL...LOW 70S AREA-WIDE. COOL AND DRY ADVECTION BEGINS IN EARNEST SUNDAY MORNING...AND PWATS DROP TO LESS THAN 1 INCH...LOWEST NORTH...WITH 850MB TEMPS DROPPING 5C THROUGH THE DAY. LOTS OF LATE-AUGUST SUNSHINE WILL SOMEWHAT COUNTERACT STRONG CAA...BUT HIGHS SUNDAY WILL LIKELY BE 5-10 DEGREES COOLER THAN SATURDAY...AND IN FACT ARE EXPECTED TO BE BELOW NORMAL...LOW 80S FAR NORTH TO UPR 80S IN THE SOUTH. A FEW SHOWERS ARE POSSIBLE...ESPECIALLY EARLY IN THE DAY ACROSS THE SC ZONES CLOSER TO THE FRONT...BUT ACTIVITY WILL NOT BE WIDESPREAD OR STRONG. MUCH COOLER MINS SUNDAY NIGHT WITH MID 60S EXPECTED FAR NORTH IN THE DRY COLUMN...UPPER 60S NEAR THE SOUTH SANTEE RIVER AND ON THE BEACHES. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 300 PM FRIDAY...THE EXTENDED FORECAST WILL GENERALLY BE DRY AND SEASONABLE AS A MID LEVEL RIDGE INITIALLY OVER THE MISSISSIPPI VALLEY SHIFTS TO MORE OF A SOUTHERN POSITION BY THE END OF THE PERIOD. AT THE SURFACE...HIGH PRESSURE WILL WEDGE DOWN THE EAST COAST AND EXTEND DOWN INTO GEORGIA FOR MONDAY THROUGH WEDNESDAY. BEYOND THIS...THE FEATURE BREAKS DOWN LEAVING A WEAK PATTERN AT THE SURFACE AND ISOLATED SHOWERS AND THUNDERSTORMS MAKE AN APPEARANCE IN THE FORECAST. THE CHANCES WILL NOT BE GOOD UNTIL FRIDAY WHEN ANOTHER FRONT DROPS INTO THE REGION PROVIDING A BETTER FOCUS. TEMPERATURES WILL BE SLIGHTLY BELOW CLIMATOLOGY MONDAY THROUGH WEDNESDAY WITH THE AXIS OF SURFACE HIGH PRESSURE PROVIDING A COOL NORTHEAST FLOW. THURSDAY AND FRIDAY SEE MODERATING VALUES CLOSER TO OR EVEN A BIT ABOVE NORMAL. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 06Z...KILM IS THE COOL SPOT ACROSS THE CWA TONIGHT THANKS TO THE EARLIER TORRENTIAL RAINFALL. HAVE INCLUDED TEMPO MVFR VSBYS FOR KILM IN THE EARLY MORNING HOURS...BUT INCREASING MID/HIGH CLOUDS OVERNIGHT SHOULD AGAIN LOWER THE FOG THREAT. DESPITE DEWPOINTS IN THE UPPER 70S AT KCRE/KMYR...SFC WINDS WILL LIKELY INHIBIT BR FORMATION AT THESE TERMS. CONVECTION OVER CENTRAL NC ASSOCIATED WITH ANOTHER UPPER DISTURBANCE IS MOVING TOWARD OUR AREA...BUT THE HRRR TENDS TO WEAKEN THE ACTIVITY AS IT NEARS THE CWA. THEREFORE WILL NOT MENTION VCSH DURING THE OVERNIGHT HOURS. A COLD FRONT WILL DROP SOUTHWARD ACROSS NC THIS MORNING... APPROACHING KLBT/KILM AROUND 12Z. MODELS SUGGEST THE FRONT MAY GET HUNG UP ACROSS OUR CWA DURING THE DAY BEFORE CLEARING THE CAROLINAS LATER IN THE PERIOD. WE COULD SEE SOME SHOWERS ACROSS OUR NORTHERN ZONES THIS MORNING...BUT CONFIDENCE IS FAIRLY LOW. BETTER CHANCES FOR CONVECTION WILL BE THIS AFTN WITH THE FRONT LINGERING OVER THE AREA...ENHANCED BY SEA BREEZE AND BOUNDARY COLLISIONS. HAVE INCLUDED VCSH FOR ALL TERMS AFTER 18Z. LIGHT/VRBL WINDS IN THE EARLY MORNING WILL BECOME NORTH AND THEN NORTHEAST BEHIND THE FRONT...REMAINING BELOW 10 KT. KCRE/KMYR WILL LIKELY SEE E-SE WINDS IN THE AFTN BEHIND THE SEA BREEZE BEFORE THE FRONT PASSES THROUGH. EXTENDED OUTLOOK...MVFR/IFR CIGS/VSBYS POSSIBLE ON SUN MORNING. OTHERWISE EXPECT VFR TO PREVAIL SUN THROUGH WED AS HIGH PRESSURE RIDGES OVER THE EAST COAST IN THE WAKE OF A COLD FRONT. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1:40 AM SATURDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. RELEVANT PORTION OF PREVIOUS DISCUSSION FOLLOWS BELOW: ISOLATED SHOWERS AND T-STORMS COULD DEVELOP LATER TONIGHT AS A SECOND UPPER LEVEL DISTURBANCE APPROACHES FROM THE NORTH. A COLD FRONT ACROSS NORTH-CENTRAL NORTH CAROLINA WILL SINK SOUTHWARD OVERNIGHT...REACHING AS FAR SOUTH AS MYRTLE BEACH BY DAYBREAK SATURDAY. UNTIL THEN...SOUTHWEST WINDS 10-15 KNOTS ARE EXPECTED ALONG WITH 2 FOOT SEAS...EVENLY SPLIT BETWEEN A SOUTHEASTERLY SWELL AND A SOUTHWEST WIND CHOP. SCATTERED THUNDERSTORMS AHEAD OF THE FRONT WILL BE MOST NUMEROUS THIS EVENING IN THE CAPE FEAR-AREA WATERS. ANY STORMS WILL BE CAPABLE OF PRODUCING GUSTY OUTFLOW WINDS AND PLENTY OF LIGHTNING. ALTHOUGH COVERAGE WILL DIMINISH OVERNIGHT THE CHANCES OF ADDITIONAL POP-UP STORMS WILL CONTINUE THROUGH DAYBREAK...SHIFTING SOUTHWARD TO THE SOUTH CAROLINA WATERS WITH THE FRONT. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 300 PM FRIDAY...BACK DOOR COLD FRONT WILL DROP ACROSS THE WATERS FROM NE TO SW DURING SATURDAY...CAUSING A WIND SHIFT TO THE N/NE BEHIND THIS BOUNDARY. WIND SHIFT WILL OCCUR FIRST ACROSS THE FAR NORTHERN LEGS OFF THE CAPE FEAR COAST...WITH WINDS BECOMING N THEN NE SATURDAY MORNING...WITH THE WATERS OFF GEORGETOWN COUNTY NOT EXPERIENCING THE WIND SHIFT UNTIL SATURDAY NIGHT. THE GRADIENT REMAINS RELAXED SATURDAY...SO WIND SPEEDS THROUGH THIS FRONTAL PASSAGE WILL BE 5-10 KTS REGARDLESS OF DIRECTION. VERY LATE SATURDAY NIGHT AND ESPECIALLY ON SUNDAY...A NE SURGE OCCURS AND WINDS QUICKLY RISE TO 15-25 KTS ACROSS THE WATERS. SEAS THROUGH THE WKND WILL BE PRIMARILY WIND DRIVEN...RISING FROM 2-3 FT SATURDAY...TO 4-6 FT ON SUNDAY...AND A SMALL CRAFT ADVISORY MAY BE NEEDED. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 300 PM FRIDAY...EXPECT NORTHEAST WINDS THROUGH THE PERIOD COURTESY OF HIGH PRESSURE ALIGNED ALONG THE EASTERN SEABOARD. WIND SPEEDS WILL BE 15-20 KNOTS MONDAY INTO MIDDAY TUESDAY RETREATING FROM THAT POINT ON TO SINGLE DIGITS BY LATER WEDNESDAY. LOWER CONFIDENCE IN SEAS AS THE SPECTRUM IS HIGHLY DEPENDENT ON HOW INVEST AL96 DOES. CURRENTLY THERE IS A FEW SIX FOOTERS ACROSS THE OUTER WATERS OF AMZ252 BUT OTHERWISE THE SEAS ARE 3-5 FEET. IF THE SYSTEM DEVELOPS MORE THAN ANTICIPATED THE SWELL ADDED TO THE SPECTRUM COULD INCREASE THE SIGNIFICANT SEAS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...JDW NEAR TERM...REK/TRA SHORT TERM...JDW LONG TERM...SHK AVIATION...BJR MARINE...REK/TRA/JDW/SHK
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1102 PM MDT FRI AUG 22 2014 .UPDATE... ISSUED AT 807 PM MDT FRI AUG 22 2014 A PRONOUNCED MIDLVL SHORTWAVE CONTINUES TO LIFT NORTHEAST ACROSS CENTRAL CO THIS EVENING PER RECENT WATER VAPOR IMAGERY. REGIONAL RADAR MOSAIC SHOWS A BAND OF MODERATE RAIN AND EMBEDDED TSTMS HAS DEVELOPED OVER THE WESTERN NE PANHANDLE...LIKELY SUPPORTED BY A MESOSCALE VORTEX CURRENTLY IN THE VICINITY OF AKO. THIS AREA OF PCPN IS EXPECTED TO SHIFT NORTH AND EAST WITH TIME...SO HAVE THE CATEGORICAL POPS CONFINED TO AREAS ALONG AND SOUTHEAST OF A LINE FROM IBM TO SNY IN OUR CWA. PCPN INTENSITY SHOULD NOT BE PARTICULARLY HEAVY TONIGHT AS INSTABILITY WAS MITIGATED BY EXTENSIVE CLOUD COVER EARLIER TODAY. THINKING ANY THREAT FOR FLASH FLOODING IS RATHER LOW. NOT SURE HOW WIDESPREAD CONVECTION WILL BE ELSEWHERE...BUT ENOUGH MOISTURE IN MONSOONAL FLOW COMBINED WITH LARGER SCALE SUPPORT SUGGESTS A CONTINUED THREAT FOR ISOLATED TO SCATTERED SHOWERS FOR MOST OF THE NIGHT. FOG COULD BE A CONCERN TONIGHT...AND WEBCAMS HAVE ALREADY SHOWN THIS IN THE LARAMIE RANGE FOOTHILLS. DO NOT THINK THIS WILL LAST LONG AS ALL MODEL GUIDANCE SHOWS LLVL WINDS SHIFTING TO THE SOUTHWEST. FARTHER E...TRUE FOG IS UNLIKELY WITH MODERATE PCPN. OPTED NOT TO INCLUDE IN THE GRIDS ATTM BUT WILL CONTINUE TO MONITOR. ONLY OTHER CHANGE TO THE FCST WAS TO BUMP LOW TEMPS UP A FEW DEGREES WHERE THE MAIN PCPN BAND IS SETTING UP. DO NOT EXPECT MUCH FOR RADIATIONAL COOLING THERE. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 300 PM MDT FRI AUG 22 2014 PRETTY ACTIVE THE NEXT 24 TO 48 HOURS. TEMPERATURES AND POPS ARE THE FORECAST CHALLENGES FOR THE SHORT TERM. CURRENTLY...WATER VAPOR IMAGERY SHOWING A PRETTY PRONOUNCED WAVE IN THE MONSOONAL FLOW MOVING NORTH THIS AFTERNOON OUT OF NEW MEXICO INTO WEST CENTRAL COLORADO. MOSAIC RADAR SHOWING WIDESPREAD SHOWERS OVER CENTRAL COLORADO EARLY THIS AFTERNOON WITH A GENERAL NORTH NORTHEAST MOVEMENT ON THE CELLS. INFRARED RADAR SHOWING COOLING CLOUD TOPS WITH THIS WAVE AND WE ARE SEEING AN UPTICK IN LIGHTNING STRIKES ACROSS WESTERN COLORADO. UPPER LOW OVER IDAHO FAIRLY DYNAMIC AS WELL WITH NUMEROUS LIGHTNING STRIKES DEVELOPING. LATEST SPC MESOANALYSIS SHOWING A SLOW EROSION OF CIN OVER EXTREME SOUTHEAST WYOMING INTO THE KIMBALL AREA...WITH CAPE VALUES AROUND 1000 J/KG ABOVE. LOOKING AT CLOUD COVER OVERHEAD...IT IS PRETTY DENSE AND WE HAVE BEEN HARD PRESSED TO GET MUCH WARMING SO FAR TODAY. 1 PM TEMPERATURES HERE AT THE OFFICE AT 69 DEGREES WITH LOW TO MID 70S OUT IN THE PANHANDLE. FOR THIS EVENING...SHORTWAVE BEGINS TO MOVE INTO SOUTHEAST WYOMING SHORTLY AFTER 00Z WITH GUIDANCE INDICATING FAIRLY WIDESPREAD CONVECTION DEVELOPING AS THIS HAPPENS. THE 16Z HRRR FORECAST HAS CONVECTION DEVELOPING HERE AT CHEYENNE AROUND THE 22Z TIME FRAME...THEN EXPANDING ACROSS SOUTHERN WYOMING INTO THE PANHANDLE AFTER WARDS. BY 01Z...MOST LOCATIONS EAST OF THE LARAMIE RANGE SHOULD BE SEEING MEASURABLE RAINFALL WITH SCATTERED SHOWERS OUT WEST. NAM SOUNDINGS FOR THE PANHANDLE SHOWING PRETTY STRONG SHEAR OUT IN THE PANHANDLE THIS EVENING. LOOKING AT EASTERLY WINDS NEAR THE SURFACE OF 15 TO 20KTS WITH SOUTHWEST 40-45KTS AT 6KM. EVENING SHIFT WILL DEFINITELY NEED TO BE WATCHING FOR SEVERE THUNDERSTORMS. 0-3KM HELICITY FOR SIDNEY AT 386M2/S2 AT 00Z. GIVEN THE THICK CLOUD COVER THOUGH...CHANCES ARE DIMMING THAT WE WILL SEE SEVERE THUNDERSTORMS. SOMETHING ELSE FOR THIS AFTN/EVE...PRECIPITABLE WATER VALUES REALLY HIGH FOR THE PANHANDLE. SIDNEY SOUNDING SHOWING 1.42 INCHES...EXTENDING UP TO CHADRON AT 1.40 INCHES. FORECAST QPF REALLY HIGH FOR THE PANHANDLE AND EXTREME EASTERN WYOMING TONIGHT. GOOD NEWS IS FORECAST STORM MOTIONS ARE FROM THE SOUTHWEST AT 14-16KTS...SO THESE STORMS SHOULD BE MOVING FAIRLY FAST. WILL NEED TO WATCH THOUGH FOR TRAINING THUNDERSTORMS AND THERE COULD BE SOME FLASH FLOODING FOR SOME AREAS THIS EVENING. GFS AND ECMWF HAVE COME INTO DECENT AGREEMENT WITH THE UPSTREAM LOW ON THIS 12Z RUN. BOTH SHOWING THE CLOSED LOW MOVING PRETTY SLOW THROUGH NORTHERN WYOMING THROUGH THE DAY SATURDAY. MOST OF SATURDAY WILL SEE SHOWERS LASTING MOST OF THE DAY. WENT SIGNIFICANTLY HIGHER ON POPS OVER GUIDANCE. DO BELIEVE THE MID SHIFT WILL PROBABLY WANT TO GO HIGHER. FINALLY SATURDAY EVENING...THE UPPER LOW MOVES OFF INTO SOUTH DAKOTA WITH RAIN ENDING FROM WEST TO EAST. GOING TO BE PRETTY COOL WITH 700MB TEMPERATURES DOWN TO +6C SATURDAY NIGHT. SHOULD SEE WIDESPREAD 40S OUT WEST FOR LOWS...WITH LOW 50S EAST. CLOUD COVER COULD PROVIDE SLIGHTLY WARMER TEMPERATURES...WE WILL HAVE TO SEE AS THE EVENT GETS CLOSER. DID GO UNDER GUIDANCE FOR SUNDAY LOWS...ESPECIALLY OUT WEST WHERE CLOUD COVER WOULD BE LESS. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 335 PM MDT FRI AUG 22 2014 MEDIUM RANGE MODELS IN GOOD AGREEMENT THROUGH EARLY TUESDAY...BUT THEN SOLUTIONS BEGIN TO DIVERGE THROUGH WEDNESDAY...WITH POOR CONSISTENCY BETWEEN THE 12Z AND 00Z MODEL RUNS APPARENT INTO LATE NEXT WEEK. EARLY IN THE WEEK...MOIST SOUTHWEST FLOW AHEAD OF A POSITIVELY TILTED UPPER LEVEL TROUGH WILL MOVE ACROSS ACROSS THE IDAHO AND INTO WESTERN WYOMING. A WEAK BOUNDARY WILL DEVELOP AND DRIFT WESTWARD ALONG THE LARAMIE RANGE...WHICH WILL RESULT IN UPSLOPE FLOW AND ENHANCE LIFT ACROSS THE HIGH PLAINS. KEPT POP BETWEEN 35 TO 60 PERCENT ACROSS THE AREA WITH A GOOD CHANCE OF AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS. ALL MODELS SHOW THIS ACTIVITY LINGERING THROUGH MONDAY NIGHT AS WELL AS A WAVE OF LOW PRESSURE DEVELOPS ALONG THE BOUNDARY...WHICH WILL EVENTUALLY TRANSITION INTO A COLD FRONT. KEPT POP AROUND 50 PERCENT MONDAY NIGHT. WILL HAVE TO WATCH FOR STRONG TO SEVERE THUNDERSTORMS MONDAY EVENING WITH CAPE VALUES AROUND 1500 TO 2000 J/KG...HIGH PW/S...AND INSTABILITY. ECMWF STILL TRENDING SLOWER WITH THE UPPER LEVEL TROUGH COMPARED TO THE GFS. THE GEM HAS TRENDED TOWARDS THE ECMWF WHILE THE GFS PUSHES THE TROUGH THROUGH THE FORECAST AREA AS EARLY AS TUESDAY AFTERNOON. THE ECMWF AND GEM SHOW THE TROUGH AXIS MOVING ACROSS THE AREA LATE TUESDAY NIGHT AND EARLY WEDNESDAY. THE GEM AND ECMWF SOLUTIONS THEN DIVERGE WITH THE ECMWF SHOWING THE SYSTEM ATTEMPTING TO CLOSE OFF ON WEDNESDAY. EITHER WAY...EXPECT TUESDAY AND TUESDAY EVENING TO REMAIN UNSETTLED WITH COOLER THAN NORMAL TEMPERATURES AND A GOOD CHANCE OF WIDESPREAD RAINFALL. HIGHS MAY STRUGGLE TO REACH THE MID TO UPPER 60S ON TUESDAY AS 700MB TEMPERATURES LOWER BELOW 5C AFTER THE FRONT MOVES THROUGH THE AREA. LOW CONFIDENCE ON THE WEDNESDAY FORECAST DUE TO SIGNIFICANT MODEL DIFFERENCES. KEPT A SLIGHT CHANCE OF SHOWERS AND TSTORMS FOR NOW DUE TO TIMING DIFFERENCES...EVEN THOUGH THE ECMWF SOLUTION IS UNLIKELY TO OCCUR. MUCH DRIER AIR MOVES INTO THE REGION THURSDAY AND FRIDAY BASED ON CURRENT MODEL RUNS AS THE RIDGE AXIS REDEVELOPS WEST OF THE ROCKY MOUNTAINS AND DRIFTS EASTWARD. BASED ON 12Z MODELS...WARMER TEMPERATURES AND DRY CONDITIONS ARE EXPECTED NEXT WEEK. HOWEVER...THERE IS A LARGE CONTRAST BETWEEN THESE SOLUTIONS AND THE PREVIOUS 00Z SOLUTIONS FROM LAST NIGHT WHICH SHOW A PACIFIC SYSTEM MOVES INTO THE REGION WITH ANOTHER STRONG COLD FRONT ENTERING WYOMING BY LATE FRIDAY. KEPT TEMPERATURES NEAR NORMAL FOR NOW WITH POP BELOW 10 PERCENT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY EVENING) ISSUED AT 1059 PM MDT FRI AUG 22 2014 IFR CIGS WILL OCCUR OVER PORTIONS OF SOUTHEAST WYOMING AND MUCH OF THE NEBRASKA PANHANDLE TONIGHT. FOG IS ALSO EXPECTED LATE TONIGHT THROUGH MID MORNING SATURDAY WITH POCKETS SOME LIFR. ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS EXPECTED FOR SATURDAY AFTERNOON AND EVENING. && .FIRE WEATHER... ISSUED AT 300 PM MDT FRI AUG 22 2014 MINIMAL FIRE WEATHER CONCERNS ACROSS THE AREA THROUGH THE NEXT FEW DAYS. UPPER LOW PRESSURE OVER IDAHO THIS AFTERNOON WILL BRING INCREASING MONSOONAL MOISTURE AND FAIRLY WIDESPREAD RAINFALL TO MUCH OF THE AREA TONIGHT INTO SATURDAY. BEST CHANCES FOR WETTING RAINS WILL BE ALONG AND EAST OF THE LARAMIE RANGE AS WELL AS THE SNOWY AND SIERRA MADRE RANGES. THE UPPER LOW WILL GRADUALLY MOVE INTO WESTERN SOUTH DAKOTA EARLY SUNDAY MORNING WITH RAINS ENDING FROM WEST TO EAST. COOLER TEMPERATURES BEHIND THE LOW WILL KEEP AFTERNOON HUMIDITIES FAIRLY HIGH WITH EXCELLENT OVERNIGHT && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ UPDATE...HAMMER SHORT TERM...CLAYCOMB LONG TERM...TJT AVIATION...SML FIRE WEATHER...CLAYCOMB
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
957 AM EDT SAT AUG 23 2014 UPDATE... HIGH PRESSURE ALOFT AND AT THE SURFACE WILL CONTINUE ACROSS THE REGION TODAY. LATEST RUNS OF THE HRRR KEEP CONVECTION VERY SPARSE ACROSS THE CWFA TODAY...AND LOW END SCT/ISOLD POPS STILL LOOK GOOD. DO THINK ANY CONVECTIVE ACTIVITY THAT DOES DEVELOP WILL BE TERRAIN BASED...OR DEPENDENT UPON ANY MESOSCALE BOUNDARIES. MODIFIED SOUNDING DOES SHOW SOME VERY GOOD SURFACE INSTABILITY PRESENT. SOUNDING ALSO ALSO SHOWS PLENTY OF DRY AIR ALOFT. SO...IF THUNDERSTORMS ARE ABLE TO DEVELOP...THEY WOULD LIKELY BE ABLE TO PRODUCE GUSTY WINDS AND FREQUENT LIGHTNING STRIKES. ISOLD SEVERE IS POSSIBLE...BUT THE POTENTIAL REMAINS LOW DUE TO VERY LITTLE CONVECTIVE COVERAGE EXPECTED. WILL ALSO BE EXTENDING THE HEAT ADVISORY NORTHWARD ON THE SW SIDE. PREV DISCUSSION... /ISSUED 721 AM EDT SAT AUG 23 2014/ SHORT TERM /TODAY THROUGH SUNDAY/... /ISSUED AT 347 AM EDT SAT AUG 23 2014/ BIG CHANGES ON TAP THROUGH THE SHORT TERM PERIOD AS MODELS CONTINUE TO SHOW JUST ONE MORE HOT DAY BEFORE A WELCOMED BACK DOOR COLD FRONT SWEEPS ACROSS THE AREA ON SUNDAY. FOR TODAY... THE DOMINATING UPPER RIDGE BEGINS TO RETREAT WESTWARD AS A SERIES OF DISTURBANCES TRACK DOWN THE EASTERN PERIPHERY AND ACROSS THE STATE DURING THE AFTERNOON AND OVERNIGHT HOURS. THIS WILL WARRANT SHOWING A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE NORTH AND EAST CENTRAL PORTIONS OF THE FORECAST AREA TODAY... AND HOLDING ONTO A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS FOR ALL AREAS TONIGHT. THE CONTINUED HEAT AND STRONG INSTABILITY COUPLED WITH SOME UPPER SUPPORT SUGGEST THE POTENTIAL FOR A FEW STRONG TO POSSIBLY SEVERE STORMS LATER THIS AFTERNOON AND EARLY EVENING... WITH STRONG TO POTENTIALLY DAMAGING WINDS BEING THE MAIN CONCERN FOR LATER TODAY. NOTHING WIDESPREAD IS EXPECTED... JUST CANNOT RULE OUT THIS POSSIBILITY AS AFTERNOON SBCAPE VALUES CLIMB BACK INTO THE 3000-4000 J/KG RANGE...ESPECIALLY ACROSS CENTRAL GA. AS FOR THE HEAT... AREA TEMPS ARE EXPECTED TO PUSH WELL INTO THE 90S AGAIN TODAY FOR MOST AREAS... ESPECIALLY ACROSS CENTRAL GA WHERE NEAR 100 DEGREE TEMPS WILL ONCE AGAIN BE FELT DURING MAX DAYTIME HEATING. THIS WILL PUSH HEAT INDEX VALUES NEAR OR ABOVE THE CRITICAL 105 DEGREE MARK FOR AREAS GENERALLY ALONG AND SOUTH OF LUMPKIN TO FORSYTH TO ATHENS LINE WHERE A HEAT ADVISORY IS CURRENTLY IN EFFECT. SEE NO REASON TO CHANGE THE ADVISORY AS CURRENTLY POSTED. THE BIG CHANGE WILL COME ON SUNDAY AS A COLD FRONT PUSHES DOWN FROM THE NORTHEAST AND PUSHES SOUTH OF COLUMBUS AND MACON BY SUNDAY EVENING. THIS WILL SPREAD CLOUDS AND INCREASING RAIN CHANCES ACROSS THE AREA... BUT MORE IMPORTANTLY... BRING MUCH RELIEF FROM THE HEAT AS SUNDAY AFTERNOON TEMPS STRUGGLE TO GET INTO THE 90S FOR MOST AREAS. ALTHOUGH SUSPECT THE CONVECTION ON SUNDAY WILL LIKELY BE MOSTLY SHOWERS... MODELS CONTINUE TO SHOW 1000-2000 J/KG OF CAPE AHEAD AND BEHIND THE FRONT SUNDAY AFTERNOON... SO WILL CONTINUE TO WORD FOR A CHANCE OF THUNDERSTORMS AS WELL. HOWEVER... NOTHING SEVERE IS EXPECTED AT THIS TIME. 39 LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... /ISSUED AT 347 AM EDT SAT AUG 23 2014/ UPPER RIDGE CONTINUES TO DOMINATE AT THE BEGINNING OF THE EXTENDED...WHILE SFC RIDGE BUILDS ACROSS THE MID ATLANTIC AND DOWN THE APPALACHIANS. WITH THE PSEUDO WEDGE BUILDING IN...WINDS BECOME EASTERLY AND CLOUD COVERAGE REMAINS BKN AT LEAST INITIALLY. CLOUD COVERAGE DOES HELP TO KEEP TEMPS ON THE COOLER SIDE ON MONDAY. DRIER AIR MOVES IN FOR THE FIRST HALF OF THE WEEK /BEHIND THE BACKDOOR FRONT/. WITH THIS...DO NOT HAVE MOISTURE AROUND FOR MUCH IN TERMS OF PRECIP AND THUS HAVE LIMITED POPS TO NO MENTION OR SLIGHT CHANCE. DIFFERENCES EXIST BETWEEN THE GFS AND ECMWF IN THE SECOND HALF THE OF THE EXTENDED. GFS BRINGS A COLD FRONT INTO THE AREA ON FRIDAY...WHILE THE ECMWF KEEPS AN UPPER RIDGE ACROSS THE SOUTHEAST. HAVE TENDED MORE TOWARDS THE GFS AND SHOWN AN INCREASE IN CLOUDS/PRECIP FOR FRIDAY ASSOCIATED WITH THE FRONT. DIFFERENCES ALSO EXIST STILL WITH HOW THE MODELS ARE HANDLING THE POTENTIAL TROPICAL SYSTEM NEXT WEEK. GFS REMAINS FURTHER WEST AND SLOWER WHILE THE ECMWF IS FURTHER EAST /ALTHOUGH LATEST RUN IS WEST OF PREVIOUS RUN/ AND FASTER. NEITHER 00Z SOLUTION BRINGS IMPACTS TO THE CWA...BUT REGARDLESS...STILL FAR OUT IN THE FORECAST AND ITS SOMETHING THAT NEEDS TO BE WATCHED AS WE HEAD INTO NEXT WEEK. 11 AVIATION... 12Z UPDATE... VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD DESPITE A BIG CHANGE IN OVERALL WEATHER PATTERN. HIGH PRESSURE WEAKENS ITS GRIP TODAY... ALLOWING SLIGHTLY BETTER CHANCE FOR SCT AFTERNOON THUNDERSTORMS. THEN A BACKDOOR COLD FRONT SWEEPS ACROSS THE AREA EARLY ON SUN... BRINGING MID LEVEL CIGS AND SCT TO NUMEROUS SHOWERS WITH SOME EMBEDDED THUNDERSTORMS TO THE AREA EARLY ON SUN. WILL SHOW TEMPO -TSRA 19-23Z TODAY... THEN PROB30 -SHRA 12-18Z SUN WITH THE FRONT. CURRENT NW WINDS PERSIST TODAY AROUND 8-11KTS... THEN SHIFT NE AROUND 08-10Z SUN WITH SPEEDS AROUND 10-12KTS ON SUN. //ATL CONFIDENCE...12Z UPDATE... MEDIUM ON ALL ELEMENTS. 39 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 97 73 88 70 / 30 30 60 30 ATLANTA 93 75 90 72 / 30 20 60 40 BLAIRSVILLE 88 69 83 67 / 30 30 60 40 CARTERSVILLE 94 71 89 72 / 30 20 60 40 COLUMBUS 98 75 94 75 / 20 20 60 40 GAINESVILLE 94 73 87 71 / 30 30 60 40 MACON 99 73 93 72 / 20 20 60 40 ROME 95 71 91 73 / 30 20 60 40 PEACHTREE CITY 94 71 90 72 / 20 20 60 40 VIDALIA 99 75 94 74 / 20 20 60 40 && .FFC WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING ZONES: BALDWIN...BIBB...BLECKLEY...CLARKE...CRAWFORD...CRISP... DODGE...DOOLY...EMANUEL...GLASCOCK...GREENE...HANCOCK... HOUSTON...JASPER...JEFFERSON...JOHNSON...JONES...LAURENS... MACON...MONROE...MONTGOMERY...MORGAN...OCONEE...OGLETHORPE... PEACH...PULASKI...PUTNAM...SCHLEY...STEWART...SUMTER... TALIAFERRO...TAYLOR...TELFAIR...TOOMBS...TREUTLEN...TWIGGS... WARREN...WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKES... WILKINSON. && $$ SHORT TERM... AVIATION...
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
947 AM EDT SAT AUG 23 2014 .UPDATE... HIGH PRESSURE ALOFT AND AT THE SURFACE WILL CONTINUE ACROSS THE REGION TODAY. LATEST RUNS OF THE HRRR KEEP CONVECTION VERY SPARSE ACROSS THE CWFA TODAY...AND LOW END SCT/ISOLD POPS STILL LOOK GOOD. DO THINK ANY CONVECTIVE ACTIVITY THAT DOES DEVELOP WILL BE TERRAIN BASED...OR DEPENDENT UPON ANY MESOSCALE BOUNDARIES. MODIFIED SOUNDING DOES SHOW SOME VERY GOOD SURFACE INSTABILITY PRESENT. SOUNDING ALSO ALSO SHOWS PLENTY OF DRY AIR ALOFT. SO...IF THUNDERSTORMS ARE ABLE TO DEVELOP...THEY WOULD LIKELY BE ABLE TO PRODUCE GUSTY WINDS AND FREQUENT LIGHTNING STRIKES. ISOLD SEVERE IS POSSIBLE...BUT THE POTENTIAL REMAINS LOW DUE TO VERY LITTLE CONVECTIVE COVERAGE EXPECTED. && .PREV DISCUSSION... /ISSUED 721 AM EDT SAT AUG 23 2014/ SHORT TERM /TODAY THROUGH SUNDAY/... /ISSUED AT 347 AM EDT SAT AUG 23 2014/ BIG CHANGES ON TAP THROUGH THE SHORT TERM PERIOD AS MODELS CONTINUE TO SHOW JUST ONE MORE HOT DAY BEFORE A WELCOMED BACK DOOR COLD FRONT SWEEPS ACROSS THE AREA ON SUNDAY. FOR TODAY... THE DOMINATING UPPER RIDGE BEGINS TO RETREAT WESTWARD AS A SERIES OF DISTURBANCES TRACK DOWN THE EASTERN PERIPHERY AND ACROSS THE STATE DURING THE AFTERNOON AND OVERNIGHT HOURS. THIS WILL WARRANT SHOWING A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE NORTH AND EAST CENTRAL PORTIONS OF THE FORECAST AREA TODAY... AND HOLDING ONTO A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS FOR ALL AREAS TONIGHT. THE CONTINUED HEAT AND STRONG INSTABILITY COUPLED WITH SOME UPPER SUPPORT SUGGEST THE POTENTIAL FOR A FEW STRONG TO POSSIBLY SEVERE STORMS LATER THIS AFTERNOON AND EARLY EVENING... WITH STRONG TO POTENTIALLY DAMAGING WINDS BEING THE MAIN CONCERN FOR LATER TODAY. NOTHING WIDESPREAD IS EXPECTED... JUST CANNOT RULE OUT THIS POSSIBILITY AS AFTERNOON SBCAPE VALUES CLIMB BACK INTO THE 3000-4000 J/KG RANGE...ESPECIALLY ACROSS CENTRAL GA. AS FOR THE HEAT... AREA TEMPS ARE EXPECTED TO PUSH WELL INTO THE 90S AGAIN TODAY FOR MOST AREAS... ESPECIALLY ACROSS CENTRAL GA WHERE NEAR 100 DEGREE TEMPS WILL ONCE AGAIN BE FELT DURING MAX DAYTIME HEATING. THIS WILL PUSH HEAT INDEX VALUES NEAR OR ABOVE THE CRITICAL 105 DEGREE MARK FOR AREAS GENERALLY ALONG AND SOUTH OF LUMPKIN TO FORSYTH TO ATHENS LINE WHERE A HEAT ADVISORY IS CURRENTLY IN EFFECT. SEE NO REASON TO CHANGE THE ADVISORY AS CURRENTLY POSTED. THE BIG CHANGE WILL COME ON SUNDAY AS A COLD FRONT PUSHES DOWN FROM THE NORTHEAST AND PUSHES SOUTH OF COLUMBUS AND MACON BY SUNDAY EVENING. THIS WILL SPREAD CLOUDS AND INCREASING RAIN CHANCES ACROSS THE AREA... BUT MORE IMPORTANTLY... BRING MUCH RELIEF FROM THE HEAT AS SUNDAY AFTERNOON TEMPS STRUGGLE TO GET INTO THE 90S FOR MOST AREAS. ALTHOUGH SUSPECT THE CONVECTION ON SUNDAY WILL LIKELY BE MOSTLY SHOWERS... MODELS CONTINUE TO SHOW 1000-2000 J/KG OF CAPE AHEAD AND BEHIND THE FRONT SUNDAY AFTERNOON... SO WILL CONTINUE TO WORD FOR A CHANCE OF THUNDERSTORMS AS WELL. HOWEVER... NOTHING SEVERE IS EXPECTED AT THIS TIME. 39 LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... /ISSUED AT 347 AM EDT SAT AUG 23 2014/ UPPER RIDGE CONTINUES TO DOMINATE AT THE BEGINNING OF THE EXTENDED...WHILE SFC RIDGE BUILDS ACROSS THE MID ATLANTIC AND DOWN THE APPALACHIANS. WITH THE PSEUDO WEDGE BUILDING IN...WINDS BECOME EASTERLY AND CLOUD COVERAGE REMAINS BKN AT LEAST INITIALLY. CLOUD COVERAGE DOES HELP TO KEEP TEMPS ON THE COOLER SIDE ON MONDAY. DRIER AIR MOVES IN FOR THE FIRST HALF OF THE WEEK /BEHIND THE BACKDOOR FRONT/. WITH THIS...DO NOT HAVE MOISTURE AROUND FOR MUCH IN TERMS OF PRECIP AND THUS HAVE LIMITED POPS TO NO MENTION OR SLIGHT CHANCE. DIFFERENCES EXIST BETWEEN THE GFS AND ECMWF IN THE SECOND HALF THE OF THE EXTENDED. GFS BRINGS A COLD FRONT INTO THE AREA ON FRIDAY...WHILE THE ECMWF KEEPS AN UPPER RIDGE ACROSS THE SOUTHEAST. HAVE TENDED MORE TOWARDS THE GFS AND SHOWN AN INCREASE IN CLOUDS/PRECIP FOR FRIDAY ASSOCIATED WITH THE FRONT. DIFFERENCES ALSO EXIST STILL WITH HOW THE MODELS ARE HANDLING THE POTENTIAL TROPICAL SYSTEM NEXT WEEK. GFS REMAINS FURTHER WEST AND SLOWER WHILE THE ECMWF IS FURTHER EAST /ALTHOUGH LATEST RUN IS WEST OF PREVIOUS RUN/ AND FASTER. NEITHER 00Z SOLUTION BRINGS IMPACTS TO THE CWA...BUT REGARDLESS...STILL FAR OUT IN THE FORECAST AND ITS SOMETHING THAT NEEDS TO BE WATCHED AS WE HEAD INTO NEXT WEEK. 11 AVIATION... 12Z UPDATE... VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD DESPITE A BIG CHANGE IN OVERALL WEATHER PATTERN. HIGH PRESSURE WEAKENS ITS GRIP TODAY... ALLOWING SLIGHTLY BETTER CHANCE FOR SCT AFTERNOON THUNDERSTORMS. THEN A BACKDOOR COLD FRONT SWEEPS ACROSS THE AREA EARLY ON SUN... BRINGING MID LEVEL CIGS AND SCT TO NUMEROUS SHOWERS WITH SOME EMBEDDED THUNDERSTORMS TO THE AREA EARLY ON SUN. WILL SHOW TEMPO -TSRA 19-23Z TODAY... THEN PROB30 -SHRA 12-18Z SUN WITH THE FRONT. CURRENT NW WINDS PERSIST TODAY AROUND 8-11KTS... THEN SHIFT NE AROUND 08-10Z SUN WITH SPEEDS AROUND 10-12KTS ON SUN. //ATL CONFIDENCE...12Z UPDATE... MEDIUM ON ALL ELEMENTS. 39 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 97 73 88 70 / 30 30 60 30 ATLANTA 93 75 90 72 / 30 20 60 40 BLAIRSVILLE 88 69 83 67 / 30 30 60 40 CARTERSVILLE 94 71 89 72 / 30 20 60 40 COLUMBUS 98 75 94 75 / 20 20 60 40 GAINESVILLE 94 73 87 71 / 30 30 60 40 MACON 99 73 93 72 / 20 20 60 40 ROME 95 71 91 73 / 30 20 60 40 PEACHTREE CITY 94 71 90 72 / 20 20 60 40 VIDALIA 99 75 94 74 / 20 20 60 40 && .FFC WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING ZONES: BALDWIN...BIBB...BLECKLEY...CLARKE...CRAWFORD...CRISP... DODGE...DOOLY...EMANUEL...GLASCOCK...GREENE...HANCOCK... HOUSTON...JASPER...JEFFERSON...JOHNSON...JONES...LAURENS... MACON...MONROE...MONTGOMERY...MORGAN...OCONEE...OGLETHORPE... PEACH...PULASKI...PUTNAM...SCHLEY...STEWART...SUMTER... TALIAFERRO...TAYLOR...TELFAIR...TOOMBS...TREUTLEN...TWIGGS... WARREN...WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKES... WILKINSON. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
959 AM CDT SAT AUG 23 2014 .DISCUSSION... 959 AM CDT THE FORECAST HAS BEEN UPDATED TO REFLECT GREATER CLOUD COVER AREAWIDE AND HIGHER POPS ACROSS MAINLY NORTH CENTRAL ILLINOIS DURING THE EARLY-MID AFTERNOON. A BROAD MESOSCALE CONVECTIVE SYSTEM WITH A LINE OF STORMS ON ITS FRONT EDGE IS CURRENTLY ADVANCING EAST OVER THE MISSISSIPPI RIVER AND FAR WESTERN ILLINOIS. THIS CONTINUES TO HOLD TOGETHER WELL WITH ONLY SUBTLE CLOUD TOP WARMING AND NO FADE IN LIGHTNING ACTIVITY OVER THE PAST COUPLE HOURS. THIS COMPLEX HAS BEEN ONGOING FOR OVER NINE HOURS SO NOT SURPRISED TO SEE THAT THE RADAR LOOP INDICATES THE LIKELY PRESENCE OF A CONVECTIVELY-INDUCED VORTICITY MAXIMUM /MCV/ IN FAR EASTERN IA. THIS WITH A COLD POOL IS HELPING TO USHER PUSH THE STORMS MORE EASTWARD THAN THE NORTHEAST MOVEMENT OF THE PARENT SHORTWAVE WOULD INDICATE. DESPITE WHAT SHOULD BE A GRADUAL FACE INTO THE EARLY AFTERNOON WITH THE UPPER SUPPORT MOVING NORTHEAST AND A DECAYING LOW-LEVEL JET PER PROFILERS...2.2 INCH PWAT AIR /99TH PERCENTILE/ AHEAD OF THE MCV WILL LIKELY SUPPORT SHOWERS AND SOME STORMS INTO NORTH CENTRAL ILLINOIS BETWEEN NOON AND 3 PM. STILL SEEING SOME EMBEDDED HOURLY PRECIP REPORTS OF A HALF TO ONE INCH WITH THIS...AND SOME OF THIS EFFICIENCY COULD CERTAINLY OCCUR ALONG AND WEST OF I-39 DURING THE EARLY AFTERNOON. UNDER THE INFLUENCE OF WEAK UPPER LEVEL FLOW...THE MCV IS FORECAST BY THE RAP AND NAM TO CONTINUE TO SLOW AS IT MOVES INTO NORTH CENTRAL IL. DESTABILIZATION AHEAD OF IT MAY SUPPORT ISOLATED OR SCATTERED SHOWERS/STORMS LATER THIS AFTERNOON FURTHER EAST TOWARD CHICAGO AND THE I-57 CORRIDOR INTO NORTHWEST INDIANA...BUT CONFIDENCE ON THIS IS LOW AS ANVIL SHIELD WILL INHIBIT THE RATE OF WARMTH...WITH MOST GUIDANCE INDICATING THE PRESENCE OF A CAP AND LOW-LEVEL FLOW OFF THE LAKE IN FAR NORTHEAST IL. MINOR TWEAKS MADE TO HOURLY TEMPERATURES AND DEW POINTS. MTF && .PREV DISCUSSION... 327 AM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES/TIMING THROUGH THE PERIOD ALONG WITH HIGH TEMPERATURES/HEAT INDICES THROUGH MONDAY. AREAS OF FOG CONTINUE TO DEVELOP WITH VISIBILITIES DROPPING UNDER 1SM IN A FEW LOCATIONS. NOT EXPECTING WIDESPREAD DENSE FOG THIS MORNING BUT WILL NEED TO MONITOR OBS OVER THE NEXT FEW HOURS. THE FOG WILL LIFT THIS MORNING BUT WITH LITTLE CHANGE TO THE AIRMASS FOG WILL BE POSSIBLE AGAIN TONIGHT INTO SUNDAY MORNING. A FEW SHOWERS DEVELOPED ACROSS NORTHERN LAKE COUNTY IN NORTHEAST IL LATE FRIDAY EVENING AND PERSISTED FOR A FEW HOURS BEFORE DISSIPATING. OTHERWISE...CONVECTION HAS BEEN FOCUSED FURTHER WEST EARLY THIS MORNING IN THE VICINITY OF THE LOW LEVEL JET. SOME OF THIS ACTIVITY OVER EASTERN IA MAY ARRIVE ACROSS THE WESTERN CWA LATER THIS MORNING...LIKELY IN A DECAYING FORM. BUT OTHER THAN AN ISOLATED SHOWER...EXPECT THE NEXT SEVERAL HOURS TO BE MAINLY DRY. CONFIDENCE REGARDING THUNDERSTORM CHANCES THIS AFTERNOON INTO THIS EVENING IS LOW THOUGH THERE IS SOME CONSENSUS FOR DEVELOPMENT BY EARLY AFTERNOON ACROSS WESTERN/NORTHWEST IL FROM REMNANTS OF CONVECTION OVER EASTERN NEBRASKA/WESTERN IA. HOW FAR IT CONTINUES EAST OR NORTHEAST BEFORE WEAKENING IS ANOTHER UNCERTAINTY. MADE NO SIGNIFICANT CHANGES FOR TODAY MAINTAINING 30-40 POPS. TRENDS WILL NEED TO BE MONITORED THRU THE MORNING. DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES APPROACHING 2 INCHES WILL LEAD TO VERY HEAVY RAIN WITH ANY THUNDERSTORMS THAT DO DEVELOP AND POSSIBLY FLASH FLOODING...ESPECIALLY IF THE RAIN FALLS OVER HARDER HIT AREAS FROM FRIDAY MORNING. THE UPPER RIDGE THEN BUILDS ACROSS THE AREA TONIGHT AND SUNDAY AND PRECIP CHANCES LOOK BELOW MENTIONABLE FROM LATE TONIGHT THROUGH MONDAY MORNING. CAN/T COMPLETELY RULE OUT SOME ISOLATED ACTIVITY... IN PARTICULAR ON A LAKE BREEZE SUNDAY AFTERNOON. A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY WITH SOME DIFFERENCES AS TO HOW FAR SOUTH THIS BOUNDARY WILL SETTLE MONDAY AFTERNOON INTO MONDAY NIGHT. THIS WOULD LIKELY BE THE NEXT CHANCE OF THUNDERSTORMS WITH THE GEM/ECMWF BOTH PUSHING THE FRONT THROUGH MUCH OF THE CWA BY TUESDAY MORNING. THIS BOUNDARY THEN MEANDERS NEAR THE IL/WI BORDER INTO THURSDAY WITH THE POSSIBILITY OF A PROLONGED UNSETTLED PATTERN ACROSS THE AREA. CLOUD COVER/CONVECTION TODAY WILL LIKELY KEEP TEMPS IN THE 80S... THOUGH WITH THE URBAN AREAS STARTING FROM LOWER/MID 70S...ANY LONGER PERIOD OF SUNSHINE TODAY COULD ALLOW A FEW PLACES TO TAG 90. TEMPS WILL WARM A FEW DEGREES SUNDAY BUT SOUTHEASTERLY WINDS WILL KEEP THE LAKESHORE COOLER. MONDAY LOOKS TO BE THE BEST CHANCE FOR TEMPS INTO THE LOWER 90S CWA WIDE BUT WILL BE DEPENDENT ON CLOUD COVER AND TIMING/ARRIVAL OF ANY PRECIP. DEWPOINTS MAY LOWER A FEW DEGREES...BACK INTO THE MID/UPPER 60S ACROSS PARTS OF THE AREA SUNDAY. HEAT INDICES COULD RANGE FROM LOWER/MID 90S TO 100-105 FAR SOUTHWEST. DEWPOINTS THEN BACK INTO THE 70S EVERYWHERE MONDAY WITH HEAT INDICES CLOSER TO 100-105 MOST AREAS WITH STILL THE POTENTIAL TO REACH HEAT ADVISORY CRITERIA ACROSS THE FAR SOUTHERN CWA MONDAY AFTERNOON. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * MVFR VISIBILITY AND CIG IMPROVING BY 15Z-16Z. * EAST TO NORTHEAST WINDS THROUGH THE DAY WITH SPEEDS POSSIBLY APPROACHING 10 KT. * LOW CHANCE FOR SHRA/TSRA...ESPECIALLY LATE THIS AFTERNOON AND EARLY THIS EVE. * CHANCE FOR REDUCED CIGS/VSBY OVERNIGHT. MTF/MDB //DISCUSSION...UPDATED 14Z... CIGS AND VISBYS HAVE RAPIDLY IMPROVED OVER ORD AND MDW...WITH THE GREATER RESTRICTIONS UNDER MORE STABILITY JUST TO THE NORTH OF ORD. REGARDING WIND SPEED THIS AFTERNOON...VAD WIND PROFILERS ARE INDICATING 10 KT OF EASTERLY FLOW AROUND 2000 FT WHICH WILL BE IN THE MIXED LAYER THIS AFTERNOON BASED ON TEMPERATURE FORECASTS. SO MAY SEE AT LEAST SPORADIC 10 KT WINDS 18Z AND AFTER. AS FOR STORMS NEAR THE MISSISSIPPI RIVER THIS SHOULD CONTINUE TO VERY SLOWLY FADE AS IT MOVES EAST-NORTHEAST. HAVE ADDED VCSH MENTION TO RFD AT THIS TIME AND MAY HAVE TO MENTION SHOWERS WITH TEMPORARY THUNDER DEPENDING ON OBSERVATIONAL AND LIGHTNING TRENDS. MTF PREV DISCUSSION...UPDATED 12Z... WEAK LOW LEVEL FLOW FROM LAKE MICHIGAN COMBINED WITH THE VERY MOIST AIRMASS HAS ALLOWED STRATUS/FOG TO SLOWLY PUSH INLAND THIS MORNING. WITH ABUNDANT CIRRUS OVERHEAD WITH MORE UPSTREAM FROM CONVECTION ACROSS IOWA IMPROVEMENT MAY BE VERY SLOW THIS MORNING SO ADJUSTMENTS MAY BE NEEDED OVER THE NEXT FEW HOURS. WITH GYY/MDW/RFD BEING ON THE FRINGES OF THE IFR IMPROVEMENT MAY BE STEADIER THERE WITH ORD/DPA LIKELY BEING THE SLOWEST. DO EXPECT THAT VFR WILL RETURN HOWEVER. EASTERLY WINDS WILL BE IN PLACE THROUGH THE DAY WITH SPEEDS EXPECTED TO BE UNDER 10 KT. SPOTTY CONVECTION HAS BEEN FESTERING OVER FAR EASTERN IOWA AHEAD OF A MUCH LARGER COMPLEX ACROSS CENTRAL IOWA. THIS ACTIVITY IS MOVING NORTHEASTWARD BUT STEERING FLOW WOULD TAKE IT MORE EASTERLY THOUGH AT LEAST SOME DECAY IS POSSIBLE IN THE NEAR TERM. HAVE LOW CONFIDENCE IN HOW CONVECTION PLAYS OUT THE REST OF THE DAY BUT AT LEAST SCATTERED TSRA IS POSSIBLE AS THE PARENT FORCING DRIFTS TOWARD THE AREA LATER TODAY. THIS POINTS TO THE AFTERNOON/EVENING BEING THE MOST LIKELY PERIOD FOR STORMS BUT THE BEST CHANCES MAY BE FOCUSED WEST OF THE TERMINALS. GIVEN THE UNCERTAINTY WILL KEEP THE TAFS DRY FOR NOW BUT EXPECT THAT RFD MAY NEED A MENTION OF TSRA ADDED BEFORE TOO LONG. WITH CONTINUED WEAK FLOW AND HIGH HUMIDITY MORE FOG AND STRATUS WILL BE POSSIBLE TONIGHT. MDB //ORD AND MDW CONFIDENCE...UPDATED 14Z... * HIGH IN CIGS AND VISIBILITY IMPROVING THROUGH MID-MORNING. * HIGH IN WIND DIRECTION AND MEDIUM IN WIND SPEED FORECAST THROUGH TODAY. * MEDIUM THAT POTENTIAL FOR SHRA/TSRA IS LOW THROUGH THE DAY. * MEDIUM THAT THERE WILL BE SOME SORT OF CIG/VSBY REDUCTION TONIGHT. MTF/MDB //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MDB && .MARINE... 340 AM CDT BROAD LOW PRESSURE REMAINS ACROSS THE MID MISSISSIPPI RIVER VALLEY THIS MORNING WHILE STRONGER LOW PRESSURE ORGANIZES OVER THE CENTRAL HIGH PLAINS. AN UPPER LOW SPINNING OVER THE NORTHWEST U.S. WILL HELP KICK THE HIGH PLAINS LOW NORTHWARD INTO SUNDAY WHILE HIGH PRESSURE MOVES FROM QUEBEC TO NEW ENGLAND AND THE MID-ATLANTIC STATES. EAST TO NORTHEAST WINDS WILL CONTINUE ACROSS LAKE MICHIGAN TODAY BUT WILL SHIFT TO THE SOUTHEAST INTO SUNDAY...WITH SPEEDS INCREASING MODESTLY. THE MAIN TRACK OF LOW PRESSURE WILL REMAIN OFF TO THE NORTHWEST OF THE LAKE INTO THE MIDDLE OF NEXT WEEK WHICH WILL KEEP A SOUTHERLY WIND GOING...THOUGH SOUTHERN AREAS MAY SEE WINDS SHIFT ONSHORE EACH AFTERNOON WHERE THE PRESSURE GRADIENT IS WEAKER. A FRONTAL BOUNDARY IS EXPECTED TO DROP OVER NORTHERN PARTS OF THE LAKE TOWARD MIDWEEK WHICH WOULD LEAD TO EAST OR NORTHEAST WINDS ACROSS THE NORTH WITH SOUTHERLY WINDS CONTINUING SOUTH. MEDIUM RANGE GUIDANCE CONFLICTS WITH HOW QUICKLY THIS FRONT MOVES ACROSS THE LAKE AND THE STRENGTH OF COLD AIR BEHIND IT DURING THE MIDDLE OF NEXT WEEK LEADING TO LOW FORECAST CONFIDENCE BY THAT TIME. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...DENSE FOG ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1134 AM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 401 AM EDT SAT AUG 23 2014 WARM AND HUMID CONDITIONS WILL PERSIST FOR ONE MORE DAY BEFORE A BRIEF BREAK IN THE STICKY CONDITIONS ARRIVES TONIGHT INTO SUNDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND EVENING WITH CHANCES DIMINISHING TONIGHT. DRY CONDITIONS ARE EXPECTED UNTIL TUESDAY WHEN A COLD FRONT BEGINS TO APPROACH THE AREA. HIGHS WILL BE IN THE 80S WITH LOWS IN THE 60S THE NEXT COUPLE OF DAYS. && .UPDATE... ISSUED AT 1116 AM EDT SAT AUG 23 2014 FOG HAS DISSIPATED ACROSS MOST OF THE AREA THIS MORNING...WITH THE EXCEPTION BEING JUST SOME PATCHY 2-5 MILE VISIBILITIES WHERE STRATUS DECK HAS PERSISTED THE LONGEST FROM SOUTHWEST LOWER MICHIGAN SOUTHEASTWARD TO LIMA OHIO. MCS ACROSS EASTERN IOWA/NORTHWEST ILLINOIS WILL BE THE NEXT ITEM OF CONCERN TO ADDRESS FOR THE LOCAL AREA. CORFIDI VECTORS SUPPORT MORE OF AN EAST/SOUTH PROPAGATION THIS AFTERNOON...WITH ORIENTATION OF STRONGEST INSTABILITY AXIS ALSO FAVORING GENERAL PROPAGATION/DEVELOPMENT TO THE SOUTHEAST...CLIPPING ESPECIALLY SOUTHWEST PORTIONS OF THE AREA. HAVE INCREASED TO MID RANGE CHANCE POPS ACROSS THE FAR SOUTHWEST TO ACCOUNT FOR THIS...WHILE MAINTAINING OVERALL SOUTHWEST TO NORTHEAST POP GRADIENT FROM PREVIOUS FORECAST. SEVERE WEATHER POTENTIAL STILL APPEARS TO BE QUITE LOW WITH ANY LOW END/ISOLD RISK LIKELY BEING FINED TO RICHER LOW LEVEL MOISTURE AXIS ACROSS SOUTHWEST PORTIONS OF THE AREA. WHILE INSTABILITY WILL BE MAXIMIZED ACROSS THE SOUTHWEST...THIS MAY REPRESENT A MINIMUM IN DEEP LAYER SHEAR. ONLY CAVEAT TO THIS WOULD BE FOR SMALLER SCALE AREA OF LOCALLY ENHANCED SHEAR ASSOCIATED WITH CONVECTIVELY ENHANCED VORT MAX EMANATING FROM IOWA/ILLINOIS CONVECTION. GIVEN HEAVY RAINFALL OVER PAST FEW DAYS ACROSS THE SOUTHWEST...WILL ESPECIALLY HAVE TO MONITOR FOR ANY STORMS CAPABLE OF LOCALIZED HEAVIER RAINFALL. TEMPS APPEAR TO BE IN GOOD SHAPE WITH JUST SOME MINOR TWEAKS TO MORNING DIURNAL CURVE TO ACCOUNT FOR LINGERING STRATUS DECK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 401 AM EDT SAT AUG 23 2014 SEVERAL SMALLER ITEMS TO TRY TO SORT OUT FOR THE FORECAST. FIRST OFF WILL BE COMBINATION OF MOIST LOW LEVEL AIR MASS AND MOSTLY CLEAR SKIES ALLOWING FOR STRATUS/FOG DEVELOPMENT ACROSS THE AREA. OBSERVATIONS HAVE BEEN SHOWING THIS ALREADY TAKING PLACE...WITH ISSUES EXPECTED TO PERSIST THROUGH AT LEAST 10 AM BEFORE SUFFICIENT MIXING OCCURS TO HELP BREAK THINGS UP. NEXT UP WILL BE ATTEMPT TO ADVECT IN SOMEWHAT DRIER AIR FROM THE NE AGAINST THE PERSISTENT BUT WEAK SW FLOW ACROSS MUCH OF THE WESTERN GREAT LAKES. A SUBTLE BOUNDARY WAS LOCATED FROM S LK MICHIGAN TO VICINITY OF FT WAYNE. THIS FEATURE...COMBINED WITH WHAT APPEARS TO BE A MID LEVEL DISTURBANCE OR SERIES OF GRAVITY WAVES...HELPED SPARK SMALL AREAS OF SLOW MOVING SHOWERS AND STORMS THAT HAVE SINCE DISSIPATED. LOCATIONS ALONG AND SW OF THIS BOUNDARY WILL SEE A CHANCE FOR HIT OR MISS SHOWERS/STORMS THIS AFTERNOON/EVE IF SUFFICIENT HEATING CAN TAKE PLACE. WARM AND HUMID CONDITIONS WILL REMAIN UNTIL THE NE FLOW CAN STRENGTHEN SLIGHTLY AS RIDGE INFLUENCE BRIEFLY RELAXES WITH DEWPOINTS DROPPING INTO THE MID 60S (LOW 60S NE). A FEW RUNS OF THE RUC TRY TO BRING THIS DRIER AIR A BIT FASTER IN NE SECTIONS THAT CURRENTLY DEPICTED. GIVEN WEAK NATURE OF SLOW...THINK SLOWER IS BETTER AT THIS POINT UNTIL DEGREE OF MIXING CAN BE DETERMINED. AS A RESULT...HIGHS SHOULD REACH THE MID 80S WITH HEAT INDICES NEAR OR JUST INTO THE 90S. NE FLOW WILL PUSH AXIS OF BEST PRECIPITATION POTENTIAL TO THE SW OF THE REGION DURING THE EVENING HOURS...LEADING TO WHAT SHOULD BE A PLEASANTLY DRY NIGHT AS LOWS DROP INTO THE MID 60S TO NEAR 70. HAVE KEPT A LINGERING SLGT CHC OF SHOWERS IN FAR SW AREAS EARLY EVENING BUT THEN REMOVED ALL MENTION OF PRECIPITATION AFTER 3Z. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 401 AM EDT SAT AUG 23 2014 STRONG SHRTWV MOVG THROUGH NRN NEVADA THIS MORNING EXPECTED TO LIFT SLOWLY NE THROUGH THE NRN HIGH PLAINS SUNDAY WITH DOWNSTREAM RIDGE MOVG EAST ACROSS OUR CWA. LACK OF FORCING AND A LITTLE DRIER AIR ADVECTING INTO OUR AREA IN THE H925-H85 LAYER DUE TO EASTERLY FLOW AROUND STRENGTHENING ANTICYCLONE OVER THE LWR GRTLKS SUGGESTS DRY CONDITIONS ACROSS OUR AREA. GOOD DEAL OF SUNSHINE SHOULD ALLOW MIXING UP TO NEAR H850 WHICH WOULD RESULT IN HIGHS IN THE M-U80S. NRN PLAINS SHRTWV EXPECTED TO MOVE EAST TO ONTARIO ON MONDAY. RIDGE OVER THE UPR GRTLKS WILL FLATTEN OUT IN RESPONSE BUT SHOULD HOLD STRONG IN OUR AREA KEEPING CONDITIONS DRY. TEMPS EXPECTED TO CONTINUE SLOW WARMING TREND AS WINDS VEER MORE SOUTHERLY WITH HIGHS IN THE U80S/L90S. ONTARIO SHRTWV EXPECTED TO SHEAR OUT AND LIFT ENE INTO QUEBEC TUE WITH TRAILING CDFNT SINKING SLOWLY SOUTH INTO OR CLOSE TO NRN PORTION OF OUR CWA BY WED MORNING. TSTMS SHOULD DEVELOP ALONG THE FRONT AND MAY PROPAGATE SE INTO UNSTABLE AIRMASS OVER OUR AREA... BUT CAPPING INVERSION MAKES THIS SCENARIO DOUBTFUL... SO JUST CONTD WITH LOW CHC POPS. TEMPS SHOULD REMAIN WELL ABOVE NORMAL WITH HIGHS AROUND 90 AND LOWS NEAR 70. MODEL SOLUTIONS DIVERGE SIGNIFICANTLY LATE WEEK WITH ECMWF/GEM SUGGESTING NEXT STRONG SHRTWV TO MOVE INTO MEAN WRN TROF WILL CUT-OFF OVER THE ROCKIES AND THEN MOVE SLOWLY EAST... WHILE GFS SUGGESTS A MORE PROGRESSIVE SCENARIO. IN EITHER CASE... LOW POPS STILL WARRANTED FOR WED-THU... WHILE GFS INDICATES COOLER/DRIER CONDITIONS WILL OVERSPREAD THE AREA BY FRIDAY. THIS SOLUTION IN BETTER AGREEMENT WITH GOING FCST AND GIVEN EXCESSIVE UNCERTAINTY WITH LARGE MODEL DIFFERENCES... STAYED CLOSE TO PREVIOUS FCST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 648 AM EDT SAT AUG 23 2014 FOG CAUSING WIDESPREAD LIFR CONDITIONS ACROSS NRN INDIANA EARLY THIS MORNING. DIURNAL HEATING SHOULD ALLOW CONDITIONS TO GRDLY IMPROVE TO VFR BY THIS AFTN. STNRY FRONT REMAINS DRAPED ACROSS THE AREA AND MAY PROVIDE A FOCUS FOR TSRA THIS AFTN... HWVR CHANCES TOO LOW TO MENTION IN THE TAFS. DRIER AIR EXPECTED TO MOVE INTO THE AREA FROM THE EAST TONIGHT... BUT STILL SHOULD BE SUFFICIENT RADIATIONAL COOLING FOR SOME MVFR VSBYS IN BR TOWARD DAYBREAK. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...MARSILI SYNOPSIS...FISHER SHORT TERM...FISHER LONG TERM...JT AVIATION...JT VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
655 AM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 401 AM EDT SAT AUG 23 2014 WARM AND HUMID CONDITIONS WILL PERSIST FOR ONE MORE DAY BEFORE A BRIEF BREAK IN THE STICKY CONDITIONS ARRIVES TONIGHT INTO SUNDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND EVENING WITH CHANCES DIMINISHING TONIGHT. DRY CONDITIONS ARE EXPECTED UNTIL TUESDAY WHEN A COLD FRONT BEGINS TO APPROACH THE AREA. HIGHS WILL BE IN THE 80S WITH LOWS IN THE 60S THE NEXT COUPLE OF DAYS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 401 AM EDT SAT AUG 23 2014 SEVERAL SMALLER ITEMS TO TRY TO SORT OUT FOR THE FORECAST. FIRST OFF WILL BE COMBINATION OF MOIST LOW LEVEL AIR MASS AND MOSTLY CLEAR SKIES ALLOWING FOR STRATUS/FOG DEVELOPMENT ACROSS THE AREA. OBSERVATIONS HAVE BEEN SHOWING THIS ALREADY TAKING PLACE...WITH ISSUES EXPECTED TO PERSIST THROUGH AT LEAST 10 AM BEFORE SUFFICIENT MIXING OCCURS TO HELP BREAK THINGS UP. NEXT UP WILL BE ATTEMPT TO ADVECT IN SOMEWHAT DRIER AIR FROM THE NE AGAINST THE PERSISTENT BUT WEAK SW FLOW ACROSS MUCH OF THE WESTERN GREAT LAKES. A SUBTLE BOUNDARY WAS LOCATED FROM S LK MICHIGAN TO VICINITY OF FT WAYNE. THIS FEATURE...COMBINED WITH WHAT APPEARS TO BE A MID LEVEL DISTURBANCE OR SERIES OF GRAVITY WAVES...HELPED SPARK SMALL AREAS OF SLOW MOVING SHOWERS AND STORMS THAT HAVE SINCE DISSIPATED. LOCATIONS ALONG AND SW OF THIS BOUNDARY WILL SEE A CHANCE FOR HIT OR MISS SHOWERS/STORMS THIS AFTERNOON/EVE IF SUFFICIENT HEATING CAN TAKE PLACE. WARM AND HUMID CONDITIONS WILL REMAIN UNTIL THE NE FLOW CAN STRENGTHEN SLIGHTLY AS RIDGE INFLUENCE BRIEFLY RELAXES WITH DEWPOINTS DROPPING INTO THE MID 60S (LOW 60S NE). A FEW RUNS OF THE RUC TRY TO BRING THIS DRIER AIR A BIT FASTER IN NE SECTIONS THAT CURRENTLY DEPICTED. GIVEN WEAK NATURE OF SLOW...THINK SLOWER IS BETTER AT THIS POINT UNTIL DEGREE OF MIXING CAN BE DETERMINED. AS A RESULT...HIGHS SHOULD REACH THE MID 80S WITH HEAT INDICES NEAR OR JUST INTO THE 90S. NE FLOW WILL PUSH AXIS OF BEST PRECIPITATION POTENTIAL TO THE SW OF THE REGION DURING THE EVENING HOURS...LEADING TO WHAT SHOULD BE A PLEASANTLY DRY NIGHT AS LOWS DROP INTO THE MID 60S TO NEAR 70. HAVE KEPT A LINGERING SLGT CHC OF SHOWERS IN FAR SW AREAS EARLY EVENING BUT THEN REMOVED ALL MENTION OF PRECIPITATION AFTER 3Z. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 401 AM EDT SAT AUG 23 2014 STRONG SHRTWV MOVG THROUGH NRN NEVADA THIS MORNING EXPECTED TO LIFT SLOWLY NE THROUGH THE NRN HIGH PLAINS SUNDAY WITH DOWNSTREAM RIDGE MOVG EAST ACROSS OUR CWA. LACK OF FORCING AND A LITTLE DRIER AIR ADVECTING INTO OUR AREA IN THE H925-H85 LAYER DUE TO EASTERLY FLOW AROUND STRENGTHENING ANTICYCLONE OVER THE LWR GRTLKS SUGGESTS DRY CONDITIONS ACROSS OUR AREA. GOOD DEAL OF SUNSHINE SHOULD ALLOW MIXING UP TO NEAR H850 WHICH WOULD RESULT IN HIGHS IN THE M-U80S. NRN PLAINS SHRTWV EXPECTED TO MOVE EAST TO ONTARIO ON MONDAY. RIDGE OVER THE UPR GRTLKS WILL FLATTEN OUT IN RESPONSE BUT SHOULD HOLD STRONG IN OUR AREA KEEPING CONDITIONS DRY. TEMPS EXPECTED TO CONTINUE SLOW WARMING TREND AS WINDS VEER MORE SOUTHERLY WITH HIGHS IN THE U80S/L90S. ONTARIO SHRTWV EXPECTED TO SHEAR OUT AND LIFT ENE INTO QUEBEC TUE WITH TRAILING CDFNT SINKING SLOWLY SOUTH INTO OR CLOSE TO NRN PORTION OF OUR CWA BY WED MORNING. TSTMS SHOULD DEVELOP ALONG THE FRONT AND MAY PROPAGATE SE INTO UNSTABLE AIRMASS OVER OUR AREA... BUT CAPPING INVERSION MAKES THIS SCENARIO DOUBTFUL... SO JUST CONTD WITH LOW CHC POPS. TEMPS SHOULD REMAIN WELL ABOVE NORMAL WITH HIGHS AROUND 90 AND LOWS NEAR 70. MODEL SOLUTIONS DIVERGE SIGNIFICANTLY LATE WEEK WITH ECMWF/GEM SUGGESTING NEXT STRONG SHRTWV TO MOVE INTO MEAN WRN TROF WILL CUT-OFF OVER THE ROCKIES AND THEN MOVE SLOWLY EAST... WHILE GFS SUGGESTS A MORE PROGRESSIVE SCENARIO. IN EITHER CASE... LOW POPS STILL WARRANTED FOR WED-THU... WHILE GFS INDICATES COOLER/DRIER CONDITIONS WILL OVERSPREAD THE AREA BY FRIDAY. THIS SOLUTION IN BETTER AGREEMENT WITH GOING FCST AND GIVEN EXCESSIVE UNCERTAINTY WITH LARGE MODEL DIFFERENCES... STAYED CLOSE TO PREVIOUS FCST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 648 AM EDT SAT AUG 23 2014 FOG CAUSING WIDESPREAD LIFR CONDITIONS ACROSS NRN INDIANA EARLY THIS MORNING. DIURNAL HEATING SHOULD ALLOW CONDITIONS TO GRDLY IMPROVE TO VFR BY THIS AFTN. STNRY FRONT REMAINS DRAPED ACROSS THE AREA AND MAY PROVIDE A FOCUS FOR TSRA THIS AFTN... HWVR CHANCES TOO LOW TO MENTION IN THE TAFS. DRIER AIR EXPECTED TO MOVE INTO THE AREA FROM THE EAST TONIGHT... BUT STILL SHOULD BE SUFFICIENT RADIATIONAL COOLING FOR SOME MVFR VSBYS IN BR TOWARD DAYBREAK. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...FISHER SHORT TERM...FISHER LONG TERM...JT AVIATION...JT VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1054 AM EDT SAT AUG 23 2014 .SYNOPSIS... A FRONTAL BOUNDARY ACROSS THE MID ATLANTIC STATES WILL MOVE SOUTHWEST OF THE AREA TODAY. HIGH PRESSURE FROM NEW ENGLAND SLOWLY BUILDS INTO THE AREA TONIGHT INTO SUNDAY...BEFORE SETTLING OVER THE PIEDMONT EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE HRRR AND RUC ALL INDICATE THE SHOWERS OVER THE SW PART OF THE CWA WILL CONTINUE SE AND EXIT THE AREA BY EARLY AFTERNOON. OTHER SHOWERS OVER MD WILL MOVE INTO THE NORTHERN NECK AND THE DELMARVA DURING THE EARLY AFTERNOON. THESE WILL BE WEAKENING AS THEY ENCOUNTER DRIER AIR. HAVE RAISED POPS SOME ALONG THE LINES OF BOTH AREAS OF SHOWERS. ALSO HAVE LOWERED THE MAX TEMPERATURE A LITTLE AS NOT MUCH SUNSHINE TODAY AND WITH WINDS COMING OFF THE OCEAN WILL HELP TO KEEP TEMPERATURES LOWER. PREVIOUS DISCUSSION...LATEST SFC ANALYSIS REVEALS HI PRES CENTERED OVR NEW ENGLAND AND A DISORGANIZED PRES FIELD OVR THE MID ATLANTIC REGION COINCIDING WITH A WEAK STALLED FRNTAL BNDRY. ALOFT...NW FLOW CONTINUES WITH AN UPR-LEVEL RIDGE CENTERED OVR THE E-CNTRL CONUS. THE SFC FRNT WILL SAG S INTO THE CAROLINAS TDA. EXPECT ANOTHER DAY WITH SCT SHRAS/TSTMS...ESPECIALLY OVR THE PIEDMONT CLOSER TO THE FRNT. THE POTENTIAL FOR THUNDER WILL BE CONFINED AWAY FROM THE CSTS DUE TO NE FLOW WITH HI PRES BLDG OVR NEW ENGLAND. NOT EXPECTING ANY SVR WX BUT HEAVY RAIN IS PSBL IN SOME AREAS. AFTN HI TEMPS WILL RANGE FM THE UPR 70S TO NEAR 80 OVR THE LWR ERN SHORE TO THE LO-MID 80S ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... THE HIGH SURGES SSW OVER THE AREA TONIGHT INTO SUNDAY WITH THE SURFACE RIDGE AXIS SETTLING OVER THE PIEDMONT BY MONDAY. THIS WILL PRODUCE A DRYING TREND ALONG WITH A NE WIND THAT SHOULD BE RATHER BREEZY ALONG THE COAST. PARTLY TO MOSTLY SUNNY CONDITIONS ARE EXPECTED BY SUNDAY...WITH MOSTLY CLEAR/SUNNY CONDITIONS BY SUNDAY NIGHT AND MONDAY. HIGHS WILL BE BELOW SEASONAL AVERAGES THROUGH MONDAY (AROUND -1 ST DEV). HIGHS SUNDAY AND MONDAY WILL RANGE FROM THE UPPER 70S TO LOW 80S. LOWS SHOULD BE IN THE MID/UPPER 60S SUNDAY MORNING...WITH MAINLY LOW/MID 60S EXPECTED MONDAY MORNING. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... SFC HIGH PRESSURE AND UPPER LEVEL RIDGING ALONG THE EASTERN SEABOARD IS EXPECTED TO CONTINUE THROUGH MID NEXT WEEK. THIS PATTERN WILL MAINTAIN A COOLER AIRMASS OVER THE AREA THROUGH WED BEFORE THE RIDGE AXES AT THE SFC AND ALOFT ALOFT BEGIN TO SHIFT JUST EAST OF THE FA...AND MOVING OFFSHORE BY THU. THE FORECAST IS GENERALLY DRY THROUGH THE EXTENDED FORECAST PERIODS DUE TO WELL-ESTABLISHED SUBSIDENCE THROUGH THE ATMOSPHERIC PROFILE...HOWEVER A FEW SHOWERS CANNOT BE RULED OUT NEAR THE FAR SE VA/NE NC COAST ON WED DUE TO THE POTENTIAL FOR WRAPAROUND MOISTURE FROM THE TROPICAL SYSTEM PASSING WELL TO THE EAST. HIGH AND LOW TEMPERATURES WILL RUN BELOW NORMAL FROM MON NIGHT THROUGH WED NIGHT (LOWS IN THE 60S...UPPER 50S FAR WRN COUNTIES/HIGHS IN THE LOW-MID 80S...MID-UPPER 70S BEACHES) AND THEN REBOUND TWD SEASONAL NORMALS THU/THU NIGHT (HIGHS IN THE MID-UPPER 80S...UPPER 70S-LOWER 80S BEACHES/LOWS IN THE MID-UPPER 60S...AROUND 70 BEACHES). && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... KEPT A TEMPO GROUP FOR -RA NEXT FEW HOURS AT KRIC AS THE BATCH OF RAIN CROSSES THE PIEDMONT. OTW...HIGH PRS TO THE NE ALLOWING FOR DRYER AIR ALONG THE COAST WITH MAINLY VFR CNDTNS THIS AM. EXPECT VFR CIGS TODAY WITH TSCTNS SHOWING PLNTY OF MOISTURE ARND THE AREA FOR A BKN SC DECK (3-4K FT) THRU MUCH OF THE FCST PRD WITH MVFR CIGS RETURNING AFTER 00Z. SCT CONVECTION PSBL AFTER 18Z...BUT TIMING OF ANY SHWR/TSTRM PROBLEMATIC AT THIS POINT SO KEPT PCPN OUT OF FCST AFTER 18Z. OUTLOOK...MVFR/IFR CONDITIONS PSBL DUE TO STRATUS/FOG SUN MORNING. OTW...DRY WEATHER IS FORECAST FOR SEVERAL DAYS BEGINNING SUNDAY. && .MARINE... FRONTAL BOUNDARY NOW SOUTH OF THE AREA WITH HIGH PRESSURE BUILDING SOUTH FROM NEW ENGLAND. DESPITE THE ONGOING E-NE WINDS...LATEST GUIDANCE NOT AS BULLISH WITH THE WINDS THUS CREATING SOME DOUBT WHEN SCA CONDITIONS WILL START. TOUGHEST CALL WILL BE SOUTHERN CHES BAY WHERE ONLY MINIMAL CONDITIONS WILL BE MEET. MOUTH OF THE BAY WILL HAVE AN EARLIER START AND LATER FINISH TIME. SEAS (ESPECIALLY OUT NEAR 20 NM) ARE EXPECTED TO BUILD TO 5 FEET THEN REMAIN THERE THROUGH EARLY NEXT WEEK...SO EXTENDED THE SCA HEADLINES OVR THE WATERS THRU SUNDAY NIGHT. FOR CONTINUITY SAKE...WENT AHEAD AND HOISTED SCA HEADLINES FOR CURRITUCK SND SUN AND SUN NIGHT AS SCNDRY SURGE WILL LIKELY KEEP WINDS BTWN 15-20 KTS. FORECAST NEXT WEEK WILL DEPEND ON THE TRACK OF A DEVELOPING (TROPICAL) LOW PROGGED TO TRACK NE BUT REMAIN EAST OF GULF STREAM WALL. SWELL FROM THIS SYSTEM WILL EVENTUALLY AFFECT THE MID ATLNTC BEACH AREAS. && .TIDES/COASTAL FLOODING... TIDES PROGGED TO BUILD TO ABOUT 1 FOOT ABOVE NORMAL EARLY NEXT WEEK AS THE NE FLOW CONTINUES. DESPITE THE PERSISTANT ONSHORE FLOW...LEVELS EXPECTED TO REMAIN ABOUT 1/2 FOOT BELOW MINOR FLOODING THRESHOLDS. WENT WITH A MODERATE RIP CURRENT THREAT TODAY GIVEN NEARSHORE WAVES OF 2-3 FT AND A INCREASING NE WIND FLOW. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR MDZ025. NC...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR NCZ102. VA...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR VAZ098>100. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 2 AM EDT MONDAY FOR ANZ634. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 PM EDT SUNDAY FOR ANZ632. SMALL CRAFT ADVISORY FROM 8 AM SUNDAY TO 6 AM EDT MONDAY FOR ANZ633. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT MONDAY FOR ANZ654. SMALL CRAFT ADVISORY FROM 2 AM SUNDAY TO 6 AM EDT MONDAY FOR ANZ656-658. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT MONDAY FOR ANZ650-652. && $$ SYNOPSIS...AJZ/MAS NEAR TERM...MAS/JAB SHORT TERM...AJZ/MAS LONG TERM...BMD AVIATION...MPR MARINE...MPR TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1112 AM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 246 AM EDT SAT AUG 23 2014 HIGH PRESSURE TO OUR EAST WILL PROVIDE FOR LIGHT SOUTHERLY BREEZES...AND INCREASING WARMTH AND HUMIDITY THROUGH MONDAY. FOR THE MOST PART THE WEEKEND LOOKS DRY...BUT SHOWERS AND THUNDERSTORM CHANCES WILL INCREASE ON MONDAY...AHEAD OF A WEAK COLD FRONT THAT WILL ENTER NORTHERN MICHIGAN MONDAY NIGHT. && .UPDATE... ISSUED AT 1111 AM EDT SAT AUG 23 2014 SHARP MID LEVEL RIDGE AXIS CONTINUES TO POKE UP INTO THE WESTERN GREAT LAKES...DOWNSTREAM OF STRONG SHORT WAVE TROUGHING ACROSS THE NRN ROCKIES INTO THE NRN PLAINS. BROAD LOW PRESSURE ACROSS THE CENTRAL PLAINS WITH A SFC WARM FRONT DRAPED ACROSS THE MIDWEST INTO THE OHIO VALLEY...AND CONTINUES TO BE THE MAIN WEATHER FOCUS WITH YET ANOTHER ROUND OF CONVECTION IN THE MIDWEST. ACROSS NRN MICHIGAN...A BUNCH OF LITTLE THINGS HAPPENING. WEAK HIGH PRESSURE IS DRAPED ACROSS NRN MICHIGAN. BUT...SUBTLE LOW-MID LEVEL TROUGH AXIS ANALYZED ACROSS WESTERN/CENTRAL UPPER MICHIGAN ALONG NE FRINGE OF DEEPER MOISTURE GRADIENT...WHERE RUC ANALYSIS REVEALS A STRONG LOW-MID LEVEL DEFORMATION AXIS STRETCHING FROM NRN LAKE MICHIGAN UP THROUGH CENTRAL UPPER MICHIGAN. THIS IN TURN HAS/IS GENERATING A BAND OF SHOWERS UP THROUGH THAT AREA. ONE POCKET OF RAIN IN PARTICULAR HAS SEEMINGLY LATCHED ON TO THE TERRAIN INCREASE OFF LAKE MICHIGAN AND HAS BROUGHT SOME LOCALLY HEAVY RAIN THROUGH THAT AREA. NOTHING LIKE THAT HAPPENING HERE. BUT...BATCH OF VERY STUBBORN STRATUS CONTINUES TO FLOW OFF LAKE HURON WITHIN EASTERLY FLOW...BRINGING CLOUDY SKIES TO PARTS OF EASTERN UPPER AND NE LOWER MICHIGAN. STRATUS IS BEGINNING TO ERODE...BUT PROCESS IS TAKING IT/S TIME. REST OF TODAY...STRATUS IN THE EAST AND IN EASTERN UPPER MICHIGAN WILL EVENTUALLY ERODE/MIX OUT...BUT IT WILL TAKE SEVERAL MORE HOURS AS EAST FLOW CONTINUES TO PUMP COOL/MOIST MARINE AIR INTO THOSE AREAS. HAVE STRETCHED CLOUDY SKIES OUT FOR SEVERAL MORE HOURS. ELSEWHERE...HEATING INDUCED CLOUD COVER SHOULD DEVELOP OVER NW LOWER MICHIGAN AND WE MAY SEE SOME OF THAT AFOREMENTIONED DEFORMATION CLOUD COVER EXPAND DOWN INTO NW LOWER MICHIGAN AS WELL. SO... EITHER CLOUDY BECOMING PARTLY SUNNY...OR SUNNY BECOMING PARTLY SUNNY WILL BE THE NAME OF THE GAME THIS AFTERNOON. TEMPS WILL OF COURSE BE TRICKY GIVEN THE CLOUDS...AND AREAS EAST OF I-75 WILL END UP WITH THE LOWER READINGS AND HAVE TWEAKED MAX TEMPS ACCORDINGLY. BUT...IT WILL NOT TAKE MUCH FOR TEMPS TO REBOUND WHEN THE SUN FINALLY DOES BREAK OUT. JUST HOPE WE DON/T GET SOME SORT OF DIFFERENTIAL HEATING BOUNDARY ACROSS NRN LOWER/EASTERN UPPER MICHIGAN THAT POPS OFF CONVECTION THIS AFTERNOON. THINK WE ARE TOO CAPPED FOR THAT...BUT WILL SEE. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 246 AM EDT SAT AUG 23 2014 HIGH IMPACT WEATHER POTENTIAL: MINIMAL PRIMARY FORECAST CHALLENGES: DO SHOWERS MOVE INTO NORTHERN MICHIGAN? CURRENTLY, AS WAS MENTIONED AT THE EARLIER UPDATE, RAIN SHOWERS UPSTREAM OF THE FORECAST AREA ARE JUST SOUTH OF MQT AND SAW AND ALONG THE 700 MB DEWPOINT DEPRESSION GRADIENT, AND IN THE LFQ OF THE 500 MB 30 KNOT JET STREAK MOVING THROUGH N WISCONSIN. MAIN FORCING THAT IS GOING ON OVERNIGHT IS OVER FARTHER SOUTH AND WEST IN NEBRASKA WHERE THE DEEPER SFC LOW AND 500 MB VORT AND SPEED MAXES ARE DIGGING. THIS HAS GIVEN RISE TO THE COMPLEX OF STORMS IN THE CENTRAL PLAINS. THE SFC LOW IN THE E COLORADO IS LINKED BY A SLOWLY STRENGTHENING FRONT THAT STRETCHES TO THE NE THROUGH N MINNESOTA AND UP INTO JAMES BAY TO A WEAKER SFC LOW. TODAY...THE MODELS ARE IN GOOD AGREEMENT WITH THE RUC/NAM12/GFS/ECMWF/LOCAL WRF4KM SHOWING THE MORNING ISOLATED SHOWERS THAT WILL TRY TO PUSH INTO NW LOWER THIS MORNING. HOWEVER, AS THE 500 MB RIDGE OVER THE UPPER GREAT LAKES CONTINUES TO AMPLIFY, THE FORCING FOR THE SHOWERS WILL GET PUSHED TO THE NORTH AND WEST THROUGH THE AFTERNOON. THE FRONT WILL ALSO MOVE TO THE NORTH AND WEST AS THE SFC LOW IN E COLORADO MOVES OUT OVER THE CENTRAL PLAINS AND DEEPENS. THIS WILL HELP TO FOCUS MOST OF THE RAIN INSTABILITY AND THE DYNAMIC SUPPORT OVER THE NORTHERN PLAINS AS DEPICTED BY SPC. TONIGHT...THIS MOVEMENT OF THE SFC LOW OUT OF THE CENTRAL PLAINS WILL PUSH INTO NORTH DAKOTA OVERNIGHT CONTINUING TO PULL THE FOCUS AWAY FROM THE UPPER GREAT LAKES. THIS SHOULD CONTINUE OUR RAIN FREE STREAK (OR AT LEAST OUR MEASURABLE PRECIPITATION) THROUGH THE NIGHT. WHILE THERE IS SOME INSTABILITY, THE LACK OF A FOCUS AND THE CAPPING EXPECTED IN THE EVENING (BLAYER CIN 20-40 J/KG) SHOULD INHIBIT ANY SHOWERS FROM GETTING GOING. IT DOESN`T LOOK LIKE THERE IS MUCH IN THE WAY OF ELEVATED INSTABILITY AS THE SHOWALTER INDEX OVER N MICHIGAN AT ITS LOWEST IS ONLY +2C. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 246 AM EDT SAT AUG 23 2014 A HIGHLY AMPLIFIED 500MB RIDGE WILL BE OVERHEAD TO START OUR SUNDAY. AN EJECTING UPPER LOW FROM THE NORTHERN HIGH PLAINS WILL HAVE TO CREST THIS RIDGE...AND WILL PASS WELL TO OUR NORTH MONDAY NIGHT. THIS WILL FLATTEN OUT THE RIDGE...THOUGH IN OUR NECK OF THE WOODS 500MB HEIGHTS WILL HARDLY LOWER AT ALL. STILL...AN ASSOCIATED COLD FRONT WILL SLOWLY GET DRAGGED INTO THE AREA MONDAY NIGHT. UNTIL THAT HAPPENS...IT WILL BE SOMETHING OF A CHALLENGE TO GET A PRECIP THREAT GOING IN THESE PARTS. BUT IT WON/T BE CHALLENGING TO BECOME INCREASINGLY WARM AND HUMID. SUNDAY...CORE OF THE 500MB RIDGE STARTS TO SLIDE DOWNSTREAM IN THE AFTERNOON. THAT CORRESPONDS WITH A SLIGHT UPTICK IN 1000-850MB RETURN FLOW. HOWEVER...A SHORTWAVE RIDGE ASCENDING INTO THE LARGER RIDGE WILL HELP KEEP HEIGHTS HIGH. AT THE SAME TIME...SURFACE HIGH PRESSURE TO OUR EAST WILL STILL EXTEND A TOUCH OF RIDGING INTO NORTHERN MI. FROM A CONCEPTUAL MODEL STANDPOINT...IT WILL BE DIFFICULT TO FIRE OFF CONVECTION IN THIS PATTERN UNTIL HEIGHTS ALOFT FALL. INDEED...THE MODELS ARE NOT INCLINED TO PROG MUCH IF ANY CAPE. 00Z NAM HAS A LATE-DAY AXIS OF A FEW HUNDRED J/KG OF MUCAPE... HUGGING THE LAKE MI COAST FROM LTL TRAV BAY SOUTH. THIS IS WHERE LAKE BREEZE CONVERGENCE AND MOISTURE POOLING WILL BE CONCENTRATED... THANKS TO A BACKGROUND LIGHT SE SYNOPTIC SURFACE WIND. EVEN SO...AN 82/65 PARCEL HAS ABOUT 50J/KG OF CIN TO OVERCOME...THANKS TO 700MB TEMPS AROUND 9C. SO WILL MAINTAIN A DRY FORECAST. CAN GENERALLY EXPECT PARTLY SUNNY SKIES...WILL SOME BUBBLY CU AND MID/HIGH DEBRIS CLOUDS (INSTABILITY WILL BE MUCH HIGHER W OF LAKE MI). MAX TEMPS UPPER 70S (EASTERN UPPER...AND NE LOWER COAST)...TO LOW/MID 80S (INTERIOR SW SECTIONS). SUN NIGHT/MONDAY...SUB-850MB FLOW MAINTAIN AN EASTERLY COMPONENT INTO THE EVENING...BEFORE VEERING S TO EVEN SSW OVERNIGHT. THAT WILL ALLOW A JUICIER AND POTENTIALLY UNSTABLE AIRMASS TO FINALLY MAKE INROADS. HOWEVER...THAT WILL BE SLOW AT 1ST...WITH PERHAPS WESTERN CHIP/MACK THE ONLY PLACE PROGGED TO SEE SOME CAPE ARRIVE BY MORNING. THIS COULD ALLOW CONVECTION ORIGINATING IN WI A CHANCE TO GRAZE BY THAT AREA OVERNIGHT. BUT...GIVEN THE MODELS TEND TO BE TOO QUICK TO BREAK DOWN RIDGING AND CIN...WILL MAINTAIN A DRY FORECAST FOR SUN NIGHT. DEEP MOISTURE/MODERATE INSTABILITY PLUME WILL VERY SLOWLY WORK IN FROM THE WNW MONDAY...AHEAD OF A COLD FRONT ADVANCING ACROSS WI. HEIGHTS/TEMPS ALOFT HERE REMAIN HIGH...BUT ACTIVITY SHOULD DEVELOP UPSTREAM IN WI AND MOVE E AND NE TOWARD WESTERN/NORTHERN SECTIONS...ESPECIALLY LATER IN THE DAY. WILL MAINTAIN CHANCE POPS BY AFTERNOON IN THE NW 2/3DS OF THE FORECAST AREA...INCLUDING HIGH CHANCE (50) POPS IN WESTERN CHIP/MACK. MIN TEMPS NEAR 60F TO THE MID 60S. MAX TEMPS NEAR 80 TO THE MID 80S...A FEW UPPER 80S POSSIBLE IN THE INTERIOR OF NORTHERN LOWER. DEW POINTS WILL BE RISING INTO THE MID AND UPPER 60S...SO IT WILL ALSO BE QUITE STICKY ON MONDAY. REST OF THE FORECAST...SHAPING UP FOR A FAVORABLE MCS PATTERN MID-WEEK. A STALLED FRONTAL ZONE (AND A WARM/HUMID AIRMASS) WILL BE JUST TO OUR SOUTH...WITH FAST ZONAL FLOW IN THE NORTHERN LAKES. CONSALL GRIDS ARE TRYING TO NUDGE US TOWARD LIKELY POPS IN SOME PERIODS. AM BACKING AWAY FROM THIS THINKING GIVEN THAT IT/S CONVECTION WE/RE TALKING ABOUT...AND PRECIP HAS UNDERPERFORMED OVER THE LAST WEEK OR SO. TEMPS WILL BE DRIFTING BACK TOWARD OR A BIT UNDER CLIMO BY LATE IN THE WORK WEEK...THOUGH PROBABLY NOT AS COOL AS THE GFS/MEX GUIDANCE ADVERTISES...AS THE ECMWF IS SLOWER AND LESS AMPLIFIED WITH THE UPPER TROF THAT PROGRESSES INTO THE PLAINS STATES MID/LATE WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 645 AM EDT SAT AUG 23 2014 FOG TO BURN OFF THIS MORNING...THEN VFR THRU THIS EVENING. SOME FOG AGAIN LATE TONIGHT. HUMID AIRMASS WILL REMAIN IN PLACE THIS WEEKEND. WITH LIGHT WINDS AT NIGHT...FOG HAS BEEN AN ISSUE...AND THAT WILL CONTINUE. PLN/APN GETTING THE WORST OF IT THIS MORNING...LIFR AT TIMES. THAT WILL ONLY LAST 1-2 HOURS PAST 12Z AT MOST. THEN VFR. LIFR FOG IS AGAIN LIKELY AT APN/PLN LATE TONIGHT...HAVE ADDED MVFR CONDITIONS TO MBL LATE AS WELL. LIGHT WINDS. && .MARINE... ISSUED AT 246 AM EDT SAT AUG 23 2014 OVER THE NEXT 48 HOURS, THE WINDS WILL SLOWLY INCREASE AND VEER FROM THE EAST TO THE SOUTH LOW PRESSURE NEAR COLORADO DEEPENS AND MOVES INTO NORTH DAKOTA. SO TODAY THROUGH SUNDAY NIGHT, WILL EXPECT THAT WINDS AND WAVES WILL REMAIN BELOW SMALL CRAFT CONDITIONS. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...ADAM SYNOPSIS...JZ SHORT TERM...JL LONG TERM...JZ AVIATION...JZ MARINE...JL
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
612 AM CDT SAT AUG 23 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 350 AM CDT SAT AUG 23 2014 WE HAVE BEEN WATCHING AN IMPRESSIVE THUNDERSTORM COMPLEX RACE NORTH ACROSS NEBRASKA OVERNIGHT IN ASSOCIATION WITH A SHORTWAVE ROTATING NNE AROUND THE BASE OF A DEEP TROUGH CENTERED OVER IDAHO. HOWEVER...DO NOT GET TOO EXCITED ABOUT THE PROSPECTS ABOUT ANYONE IN THE MPX CWA SEEING MUCH OF THIS PRECIP TODAY...AS THIS WAA PRECIP LOOKS TO LARGELY GO AROUND THE MPX CWA. MOST CAMS SHOW TWO CONCENTRATED AREAS THIS MORNING HEADING EAST ACROSS IOWA...WITH THE OTHER BATCH OF WIDESPREAD THUNDERSTORMS TO HEAD NORTH ACROSS THE DAKOTAS. THE IOWA AREA IS IN RESPONSE TO AIR GETTING FORCED UP OVER THE REMNANTS OF A COLD FRONT...WHICH AT 3 AM WAS LOCATED JUST SOUTH OF OMAHA TO THE QUAD CITIES...WHICH IS MORE OR LESS THE AXIS WHERE THE HRRR HAS A SWATH OF HIGHER QPF FALLING. THE DAKOTAS BULLSEYE IS RESPONSE THE NOSE OF A 40 KT ESE ORIENTED LLJ THAT WILL BE WORKING NORTH IN CONJUNCTION WITH THE STRONG SHORTWAVE CURRENTLY OVER CENTRAL NEB. WITH THAT SAID...ACTIVITY OUT THERE NOW LOOKS LIKE IT SHOULD HAVE ENOUGH MOMENTUM TO AT LEAST SNEAK UP TO AREAS SOUTH/WEST OF THE MN RIVER. OTHERWISE...FOR MUCH OF THE MPX AREA...THE BAND OF STORMS WE SEE COMING NORTH NOW WILL NOT DO MUCH MORE THAN BRING A BAND OF ALTOCU THROUGH THE AREA. FOR THIS AFTERNOON...ATTENTION TURNS TO THE SEVERE POTENTIAL OUT IN WRN MN. BY THE AFTERNOON...THE BROAD SFC CYCLONE CURRENTLY SPLAYED OUT ACROSS THE CENTRAL HIGH PLAINS WILL HAVE CONSOLIDATED INTO A 1000 MB LOW NEAR THE CENTRAL ND/SD BORDER. THIS WILL HELP PULL THE FRONT IN IOWA BACK NORTH AS A WARM...WITH IT PUSHING INTO SW MN AFTER 00Z. WILL HAVE TO WAIT A WHILE FOR SFC BASED CONVECTION TO FIRE GIVEN EXTENT OF RAIN/CLOUD COVER EXPECTED ACROSS THE DAKOTAS THIS MORNING..BUT EXPECT ENOUGH HEATING TO OCCUR THIS AFTERNOON TO ALLOW FOR STORMS TO DEVELOP NEAR THE SURGING WARM FRONT ALONG THE COTEAU IN SE SODAK AROUND 21Z...AS BOTH THE NMM/ARW SHOW. THIS ACTIVITY SHOULD THEN TRACK NNE...TOWARD WEST CENTRAL AND NORTHWEST MN DURING THE EVENING...AND IT IS THIS POTENTIAL ACTIVITY THAT GIVES US THE SLIGHT RISK FOR TODAY FROM THE SPC. CERTAINLY INSTABILITY AND SHEAR ARE ADEQUATE TO SUPPORT SURFACE BASED SUPERCELLS AND THEREFOR ALL MODES OF SEVERE WEATHER. HOWEVER...FOR AS FAR EAST AS MN...SHEAR VECTORS WILL BE MORE PARALLEL THAN PERPENDICULAR TO THE FORCING...WHICH WOULD FAVOR THE CONGEALING OF ACTIVITY INTO CLUSTERS/LINES...WHICH IS WHAT IS SEEN WITH NMM/ARW REFLECTIVITY FORECASTS. THIS WOULD FAVOR THE HIGHEST TORNADO THREAT BEING ACROSS THE DAKOTAS...WHERE STORMS ARE MORE LIKELY TO BE DISCRETE...WITH WRN MN DEALING MORE WITH A POTENTIAL WIND/HAIL THREAT. FROM THE FLOOD TREAT...PWATS WILL INCREASE BACK TO AROUND 1.75 INCHES...SO CERTAINLY WILL SEE HEAVY RAIN WITH THIS ACTIVITY. HOWEVER...CURRENT EXPECTATIONS ARE THAT ACTIVITY WILL BE PROGRESSIVE ENOUGH TO KEEP ANY CONCENTRATED SWATHS OF HIGH QPF DOWN IN THE 1-2 INCH RANGE AS OPPOSED TO BEING UP IN THE 3-6 INCH RANGE LIKE WE WERE SEEING LAST WEEK. FOR TONIGHT...BEST UPPER FORCING WILL BE STAYING NW OF THE MPX CWA...SO ACTIVITY THAT MOVES INTO WRN MN WILL HEAD FOR NW/NC MN...SO CUT BACK CONSIDERABLY ON POPS...KEEPING THE ERN 2/3RDS OR SO OF THE CWA DRY. MAY STILL BE TOO FAR EAST WITH POPS TONIGHT...BUT WE SHOULD SEE SOMEWHAT OF AN EWRD PUSH WITH ACTIVITY TONIGHT AS COLD POOLS GET GENERATED. EVEN IF IT DOES NOT RAIN...IT WILL BE A MUGGY NIGHT...AS LOWER 70 DEWPS COME UP WITH THE WARM FRONT. WILL LIKELY MAKE IT TOUGH FOR MUCH OF THE MN CWA TO DIP BELOW 70 SUNDAY MORNING...WHICH WILL HAVE IMPLICATIONS ON THE POTENTIAL NEED FOR ANY HEAT HEADLINES SUNDAY. NOT WORRIED ABOUT FOG TONIGHT EITHER...AS GRADIENT WILL REMAIN STRONG THROUGH THE NIGHT...SO WILL BE ANOTHER NIGHT LIKE TONIGHT WHERE WE JUST WATCH ANY STRATUS THAT SURVIVES THE DAY TODAY EXPAND AGAIN OVERNIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 350 AM CDT SAT AUG 23 2014 THERE IS DEFINITELY SOME SPREAD IN THE MODEL GUIDANCE AS WE HEAD THROUGH THE LATTER PORTION OF THE FORECAST... BUT THE GENERAL SCENARIO SUGGESTS A TRANSITION FOR WESTERN RIDGE/EASTERN TROUGH TO MORE OF A ZONAL PATTERN BY THE END OF THE WEEK. THIS SHOULD ALLOW FOR TEMPERATURES TO TREND FROM ABOVE NORMAL TO NEAR NORMAL AS THE WEEK UNFOLDS... WITH PCPN CHANCES BEING A BIT TOUGH TO PIN DOWN DEPENDING UPON WHERE THE MAIN BAROCLINIC ZONE SETS UP. GIVEN THE SPREAD IN DETERMINISTIC AND ENSEMBLE GUIDANCE... A CONSENSUS APPROACH IS THE MOST SENSIBLE COURSE OF ACTION... SO STUCK CLOSE TO A MULTI-MODEL BLEND. THE MAIN FORECAST ISSUES LOOK TO BE THE POTENTIAL FOR EXCESSIVE HEAT/HUMIDITY SUNDAY... THEN THE POSSIBILITY OF SIGNIFICANT PCPN OVER THE SOUTHERN PORTION OF THE AREA LATE MONDAY THROUGH WEDNESDAY AS THE FRONTAL BOUNDARY HANGS UP SOMEWHERE NEAR THE MINNESOTA/IOWA BORDER. SUNDAY STILL LOOKS TO HAVE THE POTENTIAL FOR VERY WARM TEMPERATURES ACROSS THE AREA... ALONG WITH HIGH DEWPOINTS. AT THIS POINT... APPARENT TEMPERATURE FORECASTS PEAK AROUND 100 OVER A PORTION OF THE AREA SUNDAY AFTERNOON WITH FORECAST HIGHS IN THE LOW 90S AND DEWPOINTS NEAR 70. WET BULB GLOBE TEMPERATURES JUMP INTO THE LOWER TO MIDDLE 80S AS WELL... ALSO INDICATING THE POTENTIAL FOR HEAT RELATED ISSUES FOR PEOPLE WHO MAY BE OUTDOORS ON SUNDAY. THERE WILL CERTAINLY BE A SIGNIFICANT NUMBER OF PEOPLE OUTDOORS IN THE METRO AREA ON SUNDAY WITH THE GREAT MINNESOTA GET TOGETHER IN FULL SWING... SO THE POSSIBILITY OF EXCESSIVE HEAT/HUMIDITY WILL NEED TO BE MONITORED IN SUBSEQUENT FORECASTS. AT THIS POINT... THERE IS STILL SOME UNCERTAINTY IN CLOUD COVER AND WHETHER WE/LL MIX AS WELL AS SOME GUIDANCE SUGGESTS AND/OR SEE MORE LOW LEVEL EVAPORATIVE COOLING THAN ANTICIPATED. SO... WILL HIGHLIGHT THE POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK AND OTHER SERVICES... BUT HOLD OFF ON ANY ACTUAL HEADLINES AT THIS POINT. PCPN CHANCES ON SUNDAY LOOK TO BE CONFINED TO THE WESTERN/NORTHERN PORTION OF THE AREA UNTIL LATE AFTERNOON AND/OR EVENING WHEN THE COLD FRONT FINALLY STARTS TO WORK ITS WAY EAST ACROSS THE AREA. AT THAT POINT... THE MAIN LARGE SCALE FORCING WILL BE TO OUR NORTH... SO PCPN MAY BE SCATTERED IN NATURE WITH MORE WIDESPREAD ACTIVITY WITH THE SHORTWAVE AND TRIPLE-POINT TO OUR NORTH AND THE SECONDARY WARM ADVECTION/INSTABILITY NOSE TO OUR SOUTH. DEEP LAYER SHEAR WILL BE BEST TO OUR NORTH... SO ANY SEVERE POTENTIAL LOOKS TO BE CAPE- DRIVEN WITH MAINLY MULTI-CELL WIND/HAIL STORMS BEING THE CONCERN. CHANCES FOR PCPN WILL PUSH EAST SUNDAY NIGHT WITH THE FRONT... THEN WE/LL SEE HIGH PRESSURE BUILD OVER MUCH OF THE AREA. HOWEVER... THE FRONTAL BOUNDARY LOOKS TO HANG UP TO OUR SOUTH/EAST MONDAY INTO WEDNESDAY... NECESSITATING THE INCLUSION OF POPS OVER MUCH OF THE AREA DURING THAT TIME FRAME... WITH BETTER CHANCES SOUTH AND LOW CHANCES NORTH. THE FAR SOUTHERN PORTION OF THE AREA HAS SOME POTENTIAL TO SEE SIGNIFICANT RAINFALL OVER THAT PERIOD OF TIME... BUT MUCH WILL DEPEND ON WHERE SUCCESSIVE ROUNDS OF SHRA/TSRA DECIDE TO TRACK... AND IT IS TOO EARLY TO GET A GOOD HANDLE ON THAT EVOLUTION. WE SHOULD SEE HIGH PRESSURE... SUBSIDENCE... AND DRIER AIR WORK INTO THE ENTIRE AREA FROM THE NORTHWEST WEDNESDAY NIGHT THROUGH THE REMAINDER OF THE FORECAST PERIOD... WITH DRY WEATHER PREDOMINATING. HOWEVER... THE 00Z ECMWF IS A BIT SLOWER IN SHOWING THIS EVOLUTION IN COMPARISON TO ITS PREVIOUS RUNS OR THE 00Z GFS... SO WE/LL NEED TO SEE HOW THINGS EVOLVE IN SUBSEQUENT FORECASTS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 544 AM CDT SAT AUG 23 2014 WINDS HAVE STAYED UP ENOUGH THROUGH THE NIGHT TO KEEP THIS MORNINGS ISSUE AS ONE OF STRATUS. GIVEN THE STRONGER WINDS...WE WILL SEE THESE CLOUDS CLEAR OUT MORE QUICKLY THAN WE DID YESTERDAY...BUT WILL STILL BE STUCK WITH IFR/MVFR CIGS THROUGH MUCH OF THE MORNING. AREA OF TSRA ENTERING SW MN WILL STRUGGLE TO MAKE IT MUCH FARTHER INTO THE STATE AS THE LLJ SLIDES MORE EAST ACROSS IOWA...KEEPING ACTIVITY TODAY MAINLY ALONG I-90...WITH A SECOND BATCH REMAINING OUT IN THE DAKOTAS. FOR THIS AFTERNOON...EXPECT STORMS TO DEVELOP ACROSS ERN SODAK AND HEAD NE TOWARD WEST CENTRAL MN. AXN LOOKS TO BE MOST SUSCEPTIBLE TO TSRA THIS EVENING...WITH BEST CHANCES REMAINING NORTH OF RWF AND WEST OF ALL OTHER TERMINALS. WILL ALSO HAVE A WARM FROM WORKING ACROSS SW MN OVERNIGHT...WITH THE THREAT FOR MORE IFR/LIFR STRATUS EXISTING AHEAD OF THIS BOUNDARY...WITH MAINLY MVFR HZ/BR IN THE WARM SECTOR. AT THIS POINT...ONLY RWF LOOKS TO DEFINITELY SEE THE WARM SECTOR...WHILE THE WI TERMINALS WILL REMAIN OUT AHEAD OF IT. AXN/STC/MSP WILL HAVE THE BOUNDARY NEARBY BY THE END OF THE NIGHT...BUT GIVEN THE DEGREE OF LOW LEVEL MOISTURE AROUND...DECIDED TO GO WITH THE IDEA OF ANOTHER ROUND OF LOW STRATUS TO START SUNDAY. KMSP...DESPITE WHAT RADAR LOOKS LIKE TO THE SW...CONFIDENT THAT MSP WILL SEE NOTHING MORE THAN SOME SPRINKLES THIS MORNING...AS THIS ACTIVITY IS STARTING TO FAVOR IOWA BASED ON CLOUD TOP TEMPERATURES WARMING OVER MN AND REMAINING COLD OVER IA. STRATUS WILL BE EASIER TO CLEAR OUT TODAY GIVEN THE STRONGER WINDS. TONIGHT...GIVEN WHERE FORCING IS GOING...CONFIDENT IN ANY TSRA ACTIVITY REMAINING NW OF MSP. WILL BE VERY MOIST AGAIN...AND GIVEN WHAT WE HAVE SEEN THE LAST FEW MORNINGS WITH STRATUS...DECIDED TO GO WITH THE TREND OF LOW STRATUS RETURNING TO START OF SUNDAY. HOWEVER...SUNDAY SHOULD SEE IT CLEAR OUT EVEN FASTER...AS A WARM FRONT LOOKS TO QUICKLY CLEAR THE FIELD IN THE MORNING...WITH A RATHER TOASTY WARM SECTOR MOVING IN IN ITS WAKE. /OUTLOOK FOR KMSP/ SUN NIGHT...VFR. CHANCE MVFR/TSRA. WINDS BCMG W 5-10 KTS. MON...VFR. WINDS W 5-10 KTS. TUE...SHRA/TSRA AND MVFR LIKELY BY AFTERNOON. WINDS NE 5-10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM... AVIATION...MPG
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
643 AM CDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 408 AM CDT SAT AUG 23 2014 A SURFACE ANALYSIS AT 07Z INDICATED A FRONT DRAPED ACROSS SOUTHERN SOUTH DAKOTA WHILE ANOTHER WAS DRAPED FROM WEST CENTRAL INTO NORTHEAST KANSAS. A FAIRLY LARGE MCS WITH EMBEDDED MCVS CONTINUES TO LIFT FROM EASTERN AND NORTHERN NEBRASKA INTO SOUTH DAKOTA. MOST IF NOT ALL SHOWER ACTIVITY HAS ENDED FROM SOUTHWEST NEBRASKA INTO THE CENTRAL SANDHILLS. TEMPERATURES AND DEWPOINTS RANGING IN THE 60S ACROSS WRN AND NCTRL NEBR. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 408 AM CDT SAT AUG 23 2014 FOR TODAY... MODELS ARE IN FAIRLY GOOD AGREEMENT WITH A PV ANOMALY AND MID LEVEL DISTURBANCE LIFTING NORTHEAST FROM SOUTHERN UTAH CURRENTLY AND INTO NORTHEAST COLORADO BY 00Z THIS EVENING. ALONG WITH PEAK HEATING...THIS WILL PROVIDE AN INCREASE TO 30 POPS AFTER 21Z TODAY ACROSS THE NWRN HALF OF FA AND A SLIGHT CHC TO SOUTHEAST AREAS. A FAIRLY CLOUDY MORNING BASED ON RAP MODEL TIME SECTION AND LATEST SATELLITE IMAGERY. AFTERNOON CLEARING TO PARTLY CLOUDY EXPECTED FOR HIGHS FROM LOW 80S NORTHWEST TO UPPER 80S SOUTHWEST. FOR TONIGHT... THE ARW AND NMM MODELS FAVORED WHICH PERFORMED THE BEST WITH CURRENT SYSTEM EXITING THE AREA. BEST OVERALL PRECIPITATION CHANCES THIS EVENING WITH SYSTEM PASSAGE ARE 30-50 POPS WEST OF AN IML-ANW LINE AND 20-30 POPS FOR AREAS EAST. STORM MOTION WILL BE TO THE NORTHEAST AT 15 KTS. MUCH LESS RISK FOR LOCALLY HEAVY RAINFALL AS SOUNDINGS INDICATE WARM RAIN PROCESSES NOT OPERATING. NEVERTHELESS AREAS ACROSS THE WEST THIS EVENING MAY RECEIVE A TENTH TO QUARTER INCH OF NEW RAINFALL. POPS LOWERING TO 20 PERCENT AFTER MIDNIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 408 AM CDT SAT AUG 23 2014 AN ACTIVE WEATHER PATTERN WILL BE IN PLACE THROUGH THIS PERIOD WITH MULTIPLE CHANCES FOR RAIN AND COOLER TEMPERATURES EXPECTED FOR MUCH OF THE WEEK. THE UPPER LEVEL LOW NOW OVER IDAHO WILL CONTINUE TO IMPACT THE FORECAST AREA THROUGH THE FIRST PART OF THIS PERIOD. THE CURRENT FORECAST REMAINS DRY FOR SUNDAY AS THE MODELS SHOW A LACK OF MOISTURE ACROSS THE AREA. SEVERAL MODELS ARE INDICATING A NARROW BAND OF DEVELOPMENT MAINLY ACROSS CENTRAL NEBRASKA ALONG A COLD FRONT THAT LOOKS TO PUSH ACROSS THE FORECAST AREA DURING THE MORNING HOURS. THERE WILL BE SOME MID LEVEL SUPPORT AS THE UPPER LEVEL LOW LIFTS INTO NORTHWEST NORTH DAKOTA...DRAGGING WEAK SHORTWAVE ENERGY ACROSS THE CENTRAL PLAINS. WILL MONITOR FOR ANOTHER FORECAST CYCLE TO SEE IF THIS TREND CONTINUES AND IF SO...MAY NEED TO ADD SOME PRECIPITATION CHANCES FOR PART OF THE DAY SUNDAY. ALSO...A GOOD POOL OF COLD AIR WILL BE CIRCULATING AROUND THE SYSTEM...WITH MUCH COOLER AIR BEING DRAWN DOWN INTO NEBRASKA. BY 00Z TUESDAY THE MODELS ARE LIFTING THE SYSTEM FURTHER NORTH...ALLOWING WARM AIR ADVECTION TO BEGIN ACROSS THE SOUTH AND WESTERN PARTS OF THE AREA. WITH THE COOLER TEMPERATURES AND EXPECTING AT LEAST PARTIAL CLOUD COVER THE FORECAST HIGHS ARE NOW RANGING FROM THE MID 70S TO THE MID 80S. AN UPPER LEVEL LOW NOW MOVING INTO NORTHWEST CANADA OUT OF THE GULF OF ALASKA WILL DIG SOUTH INTO THE NORTHWEST PORTION OF THE CONUS BY MONDAY WHILE THE UPPER LOW TO THE NORTH PUSHES FURTHER NORTH AND EAST AWAY FROM THE AREA. THIS WILL KEEP THE CENTRAL PLAINS UNDER SOUTHWEST FLOW TO HELP BRING MOISTURE UP INTO THE AREA THROUGH MID-WEEK. FOR SUNDAY NIGHT...THE MODELS CONTINUE TO DEVELOP CONVECTION OVER NORTHEAST COLORADO...WHICH THEN SPREADS NORTHEAST INTO WESTERN NEBRASKA. THE AREA WILL BE IN THE FAVORED RIGHT ENTRANCE REGION OF THE JET AND WITH AN INCREASING LOW LEVEL JET /THOUGH NOT PARTICULARLY STRONG/ INTO THE EVENING THERE MIGHT BE ENOUGH FORCING TO KEEP THESE STORMS GOING OVERNIGHT INTO NEBRASKA SO MADE VERY LITTLE CHANGES TO ONGOING PRECIPITATION FORECAST. DURING THE DAY MONDAY...ATTEMPTED TO SHOW A TREND OF THIS ACTIVITY MOVING NORTHEAST AND THROUGH THE FORECAST AREA. MODELS SEEM TO BE SLOWING THE ADVANCEMENT OF THESE STORMS FROM PRIOR MODEL RUNS SO DON/T HAVE A HIGH DEGREE OF CONFIDENCE ON THE TIMING NOR PLACEMENT OF THESE STORM CHANCES. KEPT LIKELY CHANCES FOR RAIN FOR PORTIONS OF THE FORECAST AREA FOR MONDAY NIGHT. STILL LOOKS TO BE A SURFACE LOW SOMEWHERE OVER EASTERN COLORADO/WESTERN KANSAS WITH WARM FRONT EXTENDING INTO CENTRAL AND NORTHEAST NEBRASKA. THE MODELS ARE IN GOOD AGREEMENT WITH A WEAK SHORTWAVE TROUGH MOVING OUT OF THE FOUR CORNERS AND ACROSS THE CENTRAL PLAINS BY 12Z TUESDAY WHILE THE MAIN TROUGH REMAINS OFF TO THE WEST OVER IDAHO AND NEVADA. THE COMBINATION OF FORCING FROM THE SHORTWAVE TROUGH MOVING ACROSS THE AREA AND AN INCREASING LOW LEVEL JET BEING FOCUSED INTO WESTERN NEBRASKA FEEL THAT MONDAY NIGHT HAS THE HIGHEST CHANCES FOR RAINFALL. COULD BE ANOTHER DAY SIMILAR TO YESTERDAY WHERE THERE IS ENOUGH SHEAR AND INSTABILITY TO AT LEAST MENTION A THREAT FOR A FEW SEVERE STORMS...BUT THIS WILL DEPEND ON CONVECTION DURING THE DAY MONDAY AND WITH PRECIPITABLE WATER VALUES OVER 120 PERCENT OF NORMAL AND WARM CLOUD DEPTHS EXCEEDING 3500M STORMS SHOULD BE EFFICIENT RAIN MAKERS SO MAY BE DEALING WITH MORE OF A HEAVY RAIN THREAT. TUESDAY THROUGH FRIDAY...THE LONG RANGE MODELS BEGIN TO DIVERGE WITH HOW THEY HANDLE HOW THE TROUGH TO WEST BEHAVES. THE GFS QUICKLY PUSHES IT EAST THROUGH THE PLAINS AND INTO THE GREAT LAKES REGION BY THURSDAY WHILE THE ECMWF AND GEM ARE SLOWER AND DON/T MOVE IT OUT OF THE CENTRAL PLAINS UNTIL LATER IN THE WEEK. THIS WILL HAVE AN IMPACT ON THE SENSIBLE WEATHER AS THE SLOWER SOLUTION WOULD LINGER PRECIPITATION ACROSS THE AREA LONGER...AT LEAST THROUGH THURSDAY...WHILE THE GFS HAS A DRY FORECAST BY WEDNESDAY MORNING. HAVE NOT JUMPED ON THE SLOWER SOLUTION BUT DID LEAVE SOME SLIGHT CHANCES IN THE FORECAST THROUGH THURSDAY. WHAT IS FAIRLY CERTAIN EITHER WAY IS THAT TEMPERATURES WILL BE COOLER FOR THE WEEK. WITH PRECIPITATION AND CLOUD COVER...SOME DAYS MAY SEE HIGHS STRUGGLE TO GET INTO THE LOW AND MID 70S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 642 AM CDT SAT AUG 23 2014 NEAR TERM AVIATION CONCERN IS DURATION OF MVFR CIGS. POTENTIAL FOR CIGS BKN015-BKN020 FOR BOTH KLBF AND KVTN TERMINALS UNTIL 16Z. THEREAFTER...ANY CIGS SHOULD LIFT TO VFR AND PERSIST FOR REMAINDER OF THE PERIOD. DID NOT INCLUDE MENTION OF SHRA OR TSRA. EXPECT MAIN AREA OF DEVELOPMENT TO BE WEST OF THE TERMINALS AFTER 00Z/24TH. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...ROBERG SHORT TERM...ROBERG LONG TERM...BROOKS AVIATION...ROBERG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
537 AM CDT SAT AUG 23 2014 .UPDATE... ISSUED AT 532 AM CDT SAT AUG 23 2014 STRATUS IS BEING TO DEVELOP EARLY THIS MORNING AND THE HRRR IS DOING A DECENT JOB WITH THE LOW CLOUD DEPICTION. THE MODEL INDICATES THE MORE WIDESPREAD LOW CLOUD POTENTIAL PRIMARILY ALONG AND NORTH OF THE PLATTE RIVER...BUT CIGS ARE ALSO STARTING TO LOWER FARTHER SOUTH INTO NORTH CENTRAL KANSAS. CONFIDENCE IS NOT HIGH ON THE DEVELOPMENT OF FOG AS WINDS ARE FARILY STEADY FROM THE SOUTHEAST. MODELS SUGGEST THE LOW CLOUDS WILL PERSIST FOR AROUND THREE HOURS OR SO...BREAKING UP BY MID MORNING. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 402 AM CDT SAT AUG 23 2014 EARLY MORNING CONVECTION WAS LIFTING OUT OF OUR CWA ON THE NOSE OF THE LLVL AND AS THE WARM FRONTAL BOUNDARY LIFTS NORTHWARD AHEAD OF AN UPPER LOW EDGING EAST FM IDAHO. SEVERE WEATHER REPORTS FROM THE EVENING CONVECTION WERE LIMITED HOWEVER RAINFALL WAS WIDESPREAD WITH SEVERAL LOCATIONS RECEIVING AMOUNTS NEAR OR ABOVE ONE INCH. WINDS WILL TRANSITION SOUTHERLY AS THE WARM FRONTAL BOUNDARY LIFTS INTO THE DAKOTAS TODAY AND A PERIOD OF BREEZY CONDITIONS ARE FORECAST DURING THE AFTERNOON WITH GUSTS OF 25 TO 30 MPH POSSIBLE...ESPECIALLY FOR OUR SOUTHEASTERN ZONES. AFTERNOON TEMPS ARE LOOKING SIMILAR TO THE LAST FEW DAYS WITH HIGHS RANGING FROM THE UPPER 80S TO THE MID/UPPER 90S...AIDED BY DEEPER MIXING. CANNOT RULE OUT AN ISOLATED TSTM IN THE AFTN IN WAA AHEAD OF THE UPPER TROUGH MOVING INTO MT/WY. UNCERTAINTY EXISTS IN THE CONVECTIVE POTENTIAL TONIGHT AS THE UPPER LOW EDGES INTO THE WESTERN DAKOTAS AND A COLD FRONTAL BOUNDARY ADVANCES EASTWARD FM THE HIGH PLAINS AND REACHES OUR WESTERN CWA PRIOR TO DAYBREAK. WAA AHEAD OF THE FRONT AND CONVERGENCE/DYNAMICS ALONG THE BAROCLINIC ZONE MAY LEAD TO ISOLATED/SCATTERED STORMS. IF STORMS DEVELOP...LACK OF GOOD SHEAR AND MARGINAL INSTABILITY SHOULD LIMIT STORMS FROM BECOMING SEVERE. AS THE COLD FRONT ARRIVES LATE TONIGHT...DRIER AIR ADVECTS SOUTHEAST BEHIND THE BOUNDARY WITH DPS DROPPING OFF TO THE 50S BY SUNDAY MORNING IN OUR WESTERN ZONES. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 402 AM CDT SAT AUG 23 2014 ALOFT: A FAIRLY AMPLIFIED ERN USA RIDGE/WRN USA TROF SUN WILL GRADUALLY DEAMPLIFY NEXT WEEK AND BECOME PROGRESSIVE. A POTENT CLOSED LOW WILL WILL BE EJECTING OUT OF THE TROF...CROSSING THE DAKOTAS SUN. THIS WILL LEAVE A +TILT TROF BEHIND OVER THE WRN USA MON-TUE. THIS TROF WILL ADVANCE INTO THE PLAINS WED AND THE LAST 2-3 RUNS OF THE EC/GFS/GEM/UKMET ARE IN DECENT AGREEMENT THRU THIS TIME FRAME. AGREEMENT BREAKS DOWN THU AND WE SAW HINTS OF THIS 24 HRS AGO. THE GFS KEEPS THE TROF PROGRESSIVE WHILE THE UKMET/EC AND SOME OF THE PAST 4 GEM CYCLES BREAK THE BASE OF THE TROF OFF FROM THE WESTERLIES WHICH BECOME RE-ESTABLISHED OVER SRN CANADA. THE GFS DEVELOPS NW FLOW OVER THE PLAINS WHILE MOST OTHER MODELS HAVE THE TROF AXIS OVERHEAD. SURFACE: A COOL FRONT WILL BE CROSSING THE FCST AREA SUN MORNING. THIS FRONT WILL BECOME STATIONARY ACROSS NRN KS MON AS IT BECOMES PARALLEL WITH THE FLOW ALOFT. THE SRN FRINGE OF CANADIAN HIGH PRES WILL BUILD IN MON-TUE. HOWEVER...WITH THE TROF REMAINING TO THE W THE FRONT WILL BE CONVECTIVELY ACTIVE HAZARDS: MULTIPLE ROUNDS OF TSTMS APPEAR LIKELY WITH MON NIGHT CONTINUING AS THE HIGHEST CONFIDENCE. EXCESSIVE RAINFALL COULD BE A PROBLEM IF THESE TSTM CLUSTERS TRACK OVER SIMILAR AREAS AND WE MAY SEE HYDRO/FLOODING CONCERNS. THE DAILY DETAILS... SUN: WHILE THE BEST LOW-LVL DEWPOINTS WILL BE WHISKED AWAY BY THIS TIME FRAME...THERE IS A NARROW TONGUE OF 10-12C 850 MB DWPTS ALONG THE COOL FRONT. A COUPLE OF SHWRS/TSTMS MAY BE ON-GOING JUST NW OF THE FCST AREA AT DAYBREAK. PRESENT INDICATIONS ARE THAT THEY WILL DISSIPATE. BY AFTERNOON THIS MOIST TONGUE WILL BE OVER THE SE FRINGE OF THE FCST AREA...AND COULD SUPPORT DEVELOPMENT A TSTM OR TWO. SREF MLCAPE 2000-3000 J/KG. DEEP LAYER SHEAR AROUND 25 KTS WILL SUPPORT SEVERE MULTI-CELL CONVECTIVE MODE. SUN NIGHT: A LEE-SIDE LOW WILL BECOME ESTABLISHED NEAR PUB IN THE RIGHT REAR QUADRANT OF AN 80 KT ULJ. THE RESULT WILL BE UPSLOPE FLOW...THE DEVELOPMENT OF A LLJ AND ENHANCED THETA-E ADVECTION. RICH 850 MB DWPTS WILL ADVECT BACK INTO THE REGION LEADING TO DESTABILIZATION AND TSTM DEVELOPMENT OVER THE HIGH PLAINS. SOME OF THIS SHOULD FILTER E INTO THE FCST AREA AFTER MIDNIGHT. MON: LOTS OF UNCERTAINTY ON TEMPS. DEPENDENT ON THE AMT OF CLOUD COVER AND LINGERING TSTM ACTIVITY FROM SUN NIGHT. THIS WILL ACT TO REINFORCE THE FRONT VIA DIFFERENTIAL HEATING. AREAS N OF I-80 COULD STAY IN THE 70S WHILE N-CNTRL KS WILL BAKE INTO THE MID 90S. ANY LEFTOVER TSTM ACTIVITY SHOULD WANE DURING THE DAY. CANT RULE OUT AN ISOLATED LATE DAY TSTM OR TWO. MON NIGHT: THE MODELS CONT TO ADVERTISE MCS DEVELOPMENT AT THE NOSE OF THE LLJ. HIGH POPS ARE IN ORDER ESPECIALLY N OF HWY 6. TUE: PROBABLY A LULL IN TSTM ACTIVITY IN THE WAKE OF THE MCS. AGAIN TEMPS ARE HIGHLY UNCERTAIN. WITH CONVECTIVELY REINFORCED FRONT STILL NEAR THE KS-NEB BORDER...LATE DAY TSTM DEVELOPMENT CANT BE RULED OUT. WED-THU: FOR WHAT IT`S WORTH POTENTIAL EXISTS FOR MORE TSTMS AND IF MCS ACTIVITY IS PLACED JUST RIGHT...MULTIPLE EPISODES COULD RESULT IN EXCESSIVELY HEAVY RAINFALL. THE 18Z/22 GFS ENSEMBLES SHOW ABOVE NORMAL UNCERTAINTY IN TEMPS WED- THU. IF THE EC TURNS OUT CORRECT...WE COULD SEE SUBSTANTIAL CLOUD COVER/STRATUS TRAPPED BENEATH THE FRONT AS THE UPPER TROF MOVES IN. THE GEM/EC/GFS/DGEX ALL INDICATE POTENTIAL FOR 1 OR BOTH DAYS WITH DAYTIME TEMPS JAMMED WAYYYY BELOW NORMAL /AS COOL AS UPPER 60S TO NEAR 70/. FRI: DRY WITH SEASONABLE TEMPS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 512 AM CDT SAT AUG 23 2014 CONVECTION HAS DEPARTED THE TERMINALS AND FOR THE MOST PART DRY WEATHER IS FORECAST. THERE IS AN OUTSIDE CHANCE FOR A STORM OR TWO DURING THE AFTERNOON AND TONIGHT AHEAD OF AN APPROACHING COLD FRONT AND UPPER LEVEL TROUGH BUT CHANCES ARE NOT GREAT ENOUGH TO INCLUDE MENTION IN THE TAFS. THERE MAY BE A BRIEF VSBY RESTRICTION AROUND DAYBREAK THIS MORNING...BUT VSBYS HAVE BEEN SLOW TO DROP. OTHERWISE...LOOK FOR SOUTHERLY WINDS TO BE ON THE INCREASE WITH WIND GUSTS AROUND 25KTS POSSIBLE DURING THE AFTERNOON. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...FAY SHORT TERM...FAY LONG TERM...HALBLAUB AVIATION...FAY
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1100 AM EDT SAT AUG 23 2014 .SYNOPSIS...A COLD FRONT WILL MOVE SOUTH ACROSS SOUTHERN VIRGINIA AND NORTH CAROLINA THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD SOUTH INTO THE REGION WITH COOLER AND DRIER CONDITIONS EARLY NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... AS OF 1100 AM SATURDAY... LATEST SURFACE ANALYSIS REVEALS A COMPLEX PATTERN WITH THE BACK DOOR COLD FRONT NOW EXTENDING ACROSS NORTHEAST NC INTO SOUTHWESTERN VA AS WELL AS A SURFACE TROUGH EXTENDING ALONG THE NC/SC COAST WITH A WEAK SURFACE LOW CENTERED NEAR KILM. THE MAIN SURGE OF COLDER/DRIER AIR LAGS BEHIND THE FRONT AND IS LOCATED ACROSS EASTERN PA AND THE NORTHERN CHESAPEAKE BAY. A NORTHWEST FLOW DOMINATES THE MID AND UPPER AIR PATTERN ACROSS THE CAROLINAS WITH A STRENGTHENING NORTHERN STREAM JET POISED TO DROP INTO THE MID ATLANTIC THIS AFTERNOON...NOTE THE 105KT JET AT 200 HPA AT KIAD THIS MORNING. THE AIRMASS ACROSS THE REGION IS RATHER MOIST WITH PW VALUES OF 120-135% OF NORMAL AT KGSO/KMHX RESPECTIVELY. WITH THE ENHANCED FLOW ALOFT AND MULTIPLE MECHANISMS FOR LOCAL CONVERGENCE...NOT SURPRISED THAT HIGH RESOLUTION GUIDANCE SUGGESTS FAIRLY DECENT CONVECTIVE COVERAGE FOR THIS AFTERNOON. SHOWERS HAVE ALREADY BEGUN TO BLOSSOM IN SOUTHERN VA IN PROXIMITY TO THE SURFACE FRONT AND A DISTURBANCE IN THE NW FLOW ALOFT. OTHER CONVECTION IS BUBBLING UP IN THE COASTAL PLAIN AND COASTAL REGION NEAR THE SURFACE TROUGH. USED A BLEND OF HRRR AND RAP HOURLY PRECIP FIELDS TO GENERATE THE HOURLY POP/QPF/WX GRIDS THIS AFTERNOON. WHILE CONVECTIVE COVERAGE IS EXPECTED TO BE SOMEWHAT GENEROUS...ONLY A WEAKLY UNSTABLE AIRMASS WITH MLCAPE VALUES LESS THAN 1000 SHOULD MINIMIZE OVERAL INTENSITY. THE BEST FLOW ALOFT SHOULD REMAIN IN THE VA/MD/DE REGION WITH BULK SHEAR VALUES IN OUR CWA CLIMBING TO AROUND 2 5KTS. THE BIGGER THREAT WILL LIKELY BE ASSOCIATED WITH LOCALLY HEAVY RAIN WITH CELLS ORIENTED IN THE NW FLOW THAT REPEATEDLY MOVE OVER A GIVEN AREA. CLOUD COVER AND SCT CONVECTION SHOULD HOLD TEMPERATURES DOWN A BIT...ESPECIALLY IN THE NORTHEAST. A LITTLE BIT MORE SUNSHINE ACROSS THE SOUTHERN PIEDMONT AND SANDHILLS SHOULD ALLOW TEMPERATURES TO WARM TO AROUND OR JUST ABOVE 90. -BLAES MAIN AREA OF CONVECTION IS FORECAST TO BEGIN PUSHING TO THE SOUTH OF THE AREA BY THIS EVENING... WHILE THE LOW LEVEL FRONTAL ZONE BEGINS TO MOVE INTO THE AREA. THIS SHOULD YIELD A CONTINUED LOW END CHANCE OF AT LEAST SOME SHOWERS THOUGH. WITH A LOW LEVEL EAST TO NORTHEASTERLY FLOW TONIGHT... LOW STRATUS IS APT TO DEVELOP... WITH PATCHY LIGHT DRIZZLE EVEN. THE MAIN PUSH OF THE COOLER AIR SHOULD HOLD OFF UNTIL AFTER DAYBREAK SUNDAY. THUS... EXPECT LOW TEMPS WILL BE IN THE UPPER 60S TO LOWER 70S. SUNDAY: SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA ON SUNDAY... ALONG WITH DRIER AIR ALOFT. THIS WILL YIELD MUCH DRIER CONDITIONS ON SUNDAY... WITH SKIES BECOMING PARTLY SUNNY BY AFTERNOON. HIGH TEMPS WILL BE COOLER... AROUND 80 NORTHEAST TO MID 80S SOUTH/SOUTHWEST. CAN`T RULE OUT SOME LIGHT SHOWERS IN THE EAST TO EAST-NORTHEASTERLY LOW LEVEL FLOW IN THE MORNING TO EARLY AFTERNOON THOUGH. && .SHORT TERM /SUNDAY NIGHT AND MONDAY/... AS OF 306 AM SATURDAY... SURFACE DRY AIR RIDGE EXTENDS SOUTHWARD INTO NC FROM A PARENT HIGH POSITIONED OVER NORTHERN MID ATLANTIC. THIS SURFACE RIDGE SUPPORTED ALOFT BY A BUILDING UPPER LEVEL RIDGE...STRETCHING FROM THE MID- LOWER MS VALLEY NEWD INTO NEW ENGLAND. NELY LOW LEVEL FLOW WILL ADVECT COOLER DRIER AIR INTO CENTRAL NC. THIS DRIER AIR WILL AID TO DIMINISH ANY RESIDUAL STRATOCU. LOW LEVEL THICKNESSES DROP TO VALUES 15-20M BELOW NORMAL FOR LATE AUGUST. THIS YIELDS MAX TEMPS OF NEAR 80 ACROSS THE FAR NORTH-NW TO LOW/MID 80S FAR SOUTH. MIN TEMPS SUNDAY NIGHT LOW-MD 60S. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 306 AM SATURDAY... MONDAY NIGHT THROUGH THURSDAY...TRANQUIL WEATHER PATTERN WILL CONTINUE. UPPER LEVEL RIDGE WILL REMAIN HIGHLY AMPLIFIED UNTIL LATE WEDNESDAY INTO THURSDAY AT WHICH TIME A S/W IN THE NORTHERN STREAM WILL BE EXITING THE NORTHERN PLAINS INTO THE GREAT LAKES. THE APPROACH OF THIS SYSTEM WILL WEAKEN/SUPPRESS THE UPPER RIDGE SOUTHWARD. ASSOCIATED SFC RIDGE WILL MAINTAIN A DRY WEATHER REGIME WITH MODERATING TEMPERATURES THROUGH THURSDAY. MAX TEMPS TUESDAY NEAR 80 NORTH TO LOWER 80S SOUTH WARM TO THE MID-UPPER 80S BY THURSDAY. MIN TEMPS ALSO GRADUALLY MODIFY...FROM THE UPPER 50S-LOWER 60S TUESDAY MORNING TO THE MID 60S THURSDAY MORNING. FORECAST CONFIDENCE WANES THURSDAY INTO FRIDAY AS GFS IS MUCH FASTER WITH THE APPROACH OF THE NORTHERN STREAM S/W TOWARD THE EAST COAST VERSUS THE SLOWER ECMWF. ALSO OF CONCERN IS THE EVENTUAL TRACK OF THE TROPICAL SYSTEM THAT IS EXPECTED TO TRACK PARALLEL BUT OFFSHORE OF THE SE U.S. COAST. LATEST MODEL GUIDANCE (MAINLY ECMWF) HAS SHIFTED A LITTLE MORE TO THE WEST...WITH MAJOR TIMING DIFFERENCES (ECMWF MUCH FASTER COMPARED TO THE GFS). WITH THE TROPICAL SYSTEM OFFSHORE AND A TROUGH IN THE VICINITY OF THE GREAT LAKES/MID MS VALLEY...WOULD EXPECT A NARROW RIDGE OVER THE CAROLINAS. UNTIL THE DIFFERENCES ARE RESOLVED...FAVOR A WARM AND MAINLY DRY FORECAST FOR THE END OF THE WORK WEEK. HAVE WARMED TEMPS INTO THE MID 80-AROUND 90 FOR MAX TEMPS FRIDAY WHILE DECREASED RAIN CHANCE TO SLIGHT CHANCE. && .AVIATION /11Z SATURDAY THROUGH WEDNESDAY/... AS OF 655 AM SATURDAY... A FEW LIGHT ISOLATED TO LOCALLY SCATTERED SHOWERS CONTINUE TO MOVE ACROSS NORTHEAST PORTIONS OF CENTRAL NC THIS MORNING... POSSIBLY AFFECTING KRDU AND KRWI FOR THE NEXT COUPLE OF HOURS. HOWEVER... CONDITIONS ARE GENERALLY EXPECTED TO REMAIN VFR WITH THESE SHOWERS. GREATER CONVECTIVE COVERAGE IS EXPECTED LATER THIS MORNING INTO THE AFTERNOON AS A SERIES OF UPPER LEVEL DISTURBANCES TRACK S/SSE ACROSS THE CAROLINAS AND A BACK DOOR COLD FRONT/PRE-FRONTAL TROUGH PROGRESSES TOWARDS CENTRAL NC FROM THE N/NE. THUS... WILL MENTION A TEMPO GROUP FOR SHOWERS AND SUB-VFR CONDITIONS IN THE TAFS FOR THE AFTERNOON. THUNDERSTORMS WILL BE POSSIBLE AS WELL... BUT WILL HOLD OFF ADDING THUNDER UNTIL WE HAVE A HIGHER CONFIDENCE THAT A GIVEN LOCATION WILL BE AFFECTED BY A THUNDERSTORM. THE STRONGEST STORMS WILL HAVE THE POTENTIAL TO PRODUCE IFR/LIFR VISBYS AND STRONG WIND GUSTS. IFR TO POSSIBLY EVEN LIFR CEILINGS WILL BE POSSIBLE IN THE WAKE OF THE BACKDOOR COLD FRONT TONIGHT THROUGH MID-DAY SUNDAY...THOUGH COVERAGE AND DURATION REMAIN A BIT UNCERTAIN (HIGHEST CONFIDENCES OF SUB-VFR CONDITIONS AT KGSO/KINT). AN UPPER LEVEL RIDGE CENTERED IN VICINITY OF THE SOUTHERN APPALACHIANS SHOULD RESULT IN BETTER-THAN- NORMAL CHANCES FOR VFR CONDITIONS MON-WED...THOUGH A PERSISTENT E/NE LOW-LEVEL FLOW MAY ALLOW ADEQUATE MOISTURE FOR LOW-TOPPED SHOWER ACTIVITY...ESP AT THE EASTERN TERMINALS (FAY/RWI). && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES/BSD SHORT TERM...WSS LONG TERM...WSS AVIATION...BSD/VINCENT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
954 AM CDT SAT AUG 23 2014 .UPDATE... ISSUED AT 954 AM CDT SAT AUG 23 2014 BASED ON THE 23.12Z RAP...NOT REALLY EXPECTING THE COMPLEX OF SHOWERS AND STORMS TO DISSIPATE ANY TIME SOON. A SHORT WAVE TROUGH WILL CONTINUE TO SLOWLY MOVE NORTHEAST THROUGH THE AREA PROVIDING WEAK TO MODERATE PV ADVECTION IN THE 500-300 MB LAYER. IN THE LOW LEVELS...THE WARM FRONT WILL BE ADVANCING TOWARD THE AREA WITH WEAK FRONTOGENESIS IN THE 1000-850 MB LAYER THROUGH THE DAY. WARM AIR ADVECTION OVER THIS FRONT WILL PROVIDE 4 TO 6 UBAR/S OF UP GLIDE ON THE 310K ISENTROPIC SURFACE. THE MOISTURE TRANSPORT AT 850 MB SHOULD CONTINUE TO BE INTO AND OVER THE WARM FRONT. BASED ON ALL THIS...HAVE INCREASED THE RAIN CHANCES TO 80 PERCENT OR HIGHER FOR THE REMAINDER OF THE MORNING WEST OF THE MISSISSIPPI RIVER AND THEN ALLOWED FOR A SLOW WEAKENING TREND WHILE SPREADING THE RAIN CHANCES ACROSS MOST OF WISCONSIN DURING THE AFTERNOON. WILL LET THE DENSE FOG ADVISORY EXPIRE AS SCHEDULED AT 10 AM. MOST OF THE VISIBILITY HAS IMPROVED TO 2 MILES OR BETTER AND THE INCOMING RAIN SHOULD ALSO HELP TO CLEAN THE ATMOSPHERE UP A LITTLE BIT. UPDATE ISSUED AT 737 AM CDT SAT AUG 23 2014 A SHORT WAVE TROUGH CONTINUES TO MOVE NORTHEAST TOWARD THE FORECAST AREA THIS MORNING. THE HRRR SEEMS TO HAVE THE BEST HANDLE ON ITS PRECIPITATION...SO TRENDED THE FORECAST TOWARD IT. AS THE SYSTEM MOVES INTO OUR AREA THIS EXPECT TO SEE A GRADUAL SPLIT AS THE 850 TO 700 MB MOISTURE TRANSPORT BREAKS APART AND ONE PART GOES ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN...AND THE OTHER PIECE MOVES TO THE WEST OF OUR AREA. SO EXPECT THE AREA WHICH MOVES INTO SOUTHEAST MINNESOTA TO DISSPATE. MEANWHILE THE BETTER CHANCES OF PRECIPITATION WILL BE SOUTH OF INTERSTATE 90 AS THAT JET VEERS THROUGH THAT AREA. THERE MAY BE A REMNANT MCV THAT KEEPS SOME PRECIPITATION ACROSS WESTERN WISCONSIN THIS AFTERNOON. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 330 AM CDT SAT AUG 23 2014 SFC BOUNDARY LIES...MORE OR LESS...WEST EAST ACROSS SOUTHERN IA INTO CENTRAL ILL EARLY THIS MORNING. AN UPPER LEVEL TROUGH WILL LIFT NORTHEAST ACROSS THE NORTHERN PLAINS TODAY...AND SHOULD HELP GIVE THIS BOUNDARY A SHOVE NORTH. MEANWHILE...THERE ARE SUGGESTIONS IN THE MESO MODELS THAT AN MCV ASSOCIATED WITH THE CURRENT CONVECTION OVER NEB WOULD TAKE NORTHEAST TRACK TODAY...AND COULD SERVE AS A FOCUS FOR SHOWER/STORMS DEVELOP AS IT AND THE BOUNDARY SLIDE NORTH/NORTHEAST ACROSS THE REGION. HEAT AND HUMIDITY WILL ROUND OUT THE WEEKEND...AND HEAT ADVISORIES LOOK LIKELY FOR PORTIONS OF THE REGION. 850 MB SREF TEMP ANOMALIES AROUND +1.5 FOR SUNDAY WHILE 950 MB TEMPS ARE EXPECTED TO WARM TO 26- 28 C. HIGHS SHOULD REACH 90 ACROSS MUCH OF THE FORECAST AREA. ADD IN DEW POINTS IN THE LOWER 70S AND AFTERNOON HEAT INDICES SHOULD REACH 100 FOR A LARGE PORTION OF THE FORECAST AREA. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 330 AM CDT SAT AUG 23 2014 MODELS IN PRETTY GOOD AGREEMENT WITH THE OVERALL PATTERN THROUGH THE MIDDLE PART OF THE NEW WORK WEEK. SOLUTIONS SUGGEST AN UPPER LEVEL SHORTWAVE WILL TRACK OUT OF THE CENTRAL ROCKIES...ACROSS THE NORTHERN PLAINS AND INTO SOUTHERN CANADA SUNDAY NIGHT. ITS ASSOCIATED SFC COLD FRONT WILL DRAG ACROSS THE REGION LATE SUNDAY NIGHT INTO MONDAY...WITH THE SOUTHERN EXTENT LIKELY LINGERING IN A SOUTHWEST-NORTHEAST ORIENTATION OVER THE REGION. RIPPLES IN THE UPPER LEVEL FLOW WILL KICK OUT OF THE MEAN TROUGH...AND WORK ON THIS BOUNDARY MON-TUE. THIS NEXT TROUGH THEN SLIDES ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WED NIGHT/THU...CONTINUING TO WORK ON THAT SFC BOUNDARY...BUT ALSO PUSHING IT EAST/SOUTHEAST AS THE SYSTEM EXITS INTO THE EASTERN GREAT LAKES ON THU NIGHT. THERE ARE SOME DISCREPANCIES IN THE MODELS WITH PLACEMENT...TIMING AND STRENGTH OF THIS TROUGH...BUT THE TRENDS ARE SIMILAR AND ALL POINT TO SEVERAL DAYS WITH RAIN CHANCES. NOT OVERLY STRONG...BUT FAIRLY PERSISTENT FETCH OF 850 MB MOISTURE TRANSPORT INTO THE REGION FOR THE EARLY PART OF THE UPCOMING WEEK. WARM CLOUD DEPTHS CONTINUE TO HOVER NEAR 4 KFT WHILE PWS RANGE FROM 1.5 TO 1.75 INCHES. SO...HEAVY RAIN WOULD BE LIKELY WITH ANY THUNDERSTORMS...ESPECIALLY THE STRONGER ONES. AS FOR SEVERE POTENTIAL...AFTERNOON SBCAPES PROGGED FROM 2000-3000 J/KG PER THE GFS INTO WED...MOSTLY AROUND AND SOUTH OF THE SFC BOUNDARY. HOWEVER...WITH LOW/MID LEVEL WARMING PERSISTING...AND 700 MB TEMPS AROUND 10 C...THERE WILL BE A CAP TO DEAL WITH...AND SOME OF THIS LOW LEVEL INSTABILITY WILL NOT BE REALIZED. BUFKIT SOUNDINGS INDICATE THIS TOO. THE DEEPER...STRONGER SHEAR IS EXPECTED TO BE WELL INTO THE COLD AIR NORTH OF THE BOUNDARY...DISPLACED FROM THE STRONGER INSTABILITY. THERE IS SOME OVERLAP...SO SOME ENHANCED UPDRAFTS COULD BE SUPPORTED. OVERALL...NOT SURE THERE IS A TIME PERIOD THAT STANDS OUT FOR AN ORGANIZED SEVERE THREAT AT THIS TIME. THERE CERTAINLY COULD BE SOME SEVERE TO MARGINAL SEVERE STORMS...PERHAPS MORE PULSEY IN NATURE. MUCH DEPENDS ON BOUNDARY/SHORTWAVE INTERACTION AND TIME OF DAY. LOOK FOR UPDATES IN THE HWO FOR THE LATEST THOUGHTS ON THE DAY TO DAY SEVERE POTENTIAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 737 AM CDT SAT AUG 23 2014 KLSE WILL KEEP THE IFR STRATUS DECK THROUGH 23.13Z...AND THEN IT WILL SLOWLY RISE BECOMING MVFR BY 23.15Z AND VFR BY 23.19Z. WITH THE LINE OF CONVECTION EXPECTED TO SHEAR APART BEFORE REACHING KLSE WENT DRY FOR NOW. THE DENSE FOG AT KRST WILL GRADUALLY LIFT INTO A IFR/MVFR DECK BY 23.15Z...AND THEN THE CEILINGS WILL BECOME MVFR AND REMAIN THAT WAY THROUGH 24.00Z. IT DOES NOT LOOK THE BAND OF SHOWERS WILL BREAK UP PRIOR TO REACHING KRST...SO INCLUDED VICINITY SHOWERS BETWEEN 23.17Z AND 23.19Z. VFR CONTIONS ARE CONDITIONS ARE EXEPCTED AT BOTH SITES THIS EVENING...AND THEN THE MODELS SUGGEST DENSE FOG AGAIN. HOWEVER LOOKING AT THE WIND IN THE SOUNDINGS NOT BUYING INTO THIS...SO JUST KEPT THINGS VFR. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE...04 SHORT TERM...RIECK LONG TERM....RIECK AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
738 AM CDT SAT AUG 23 2014 .UPDATE... ISSUED AT 737 AM CDT SAT AUG 23 2014 A SHORT WAVE TROUGH CONTINUES TO MOVE NORTHEAST TOWARD THE FORECAST AREA THIS MORNING. THE HRRR SEEMS TO HAVE THE BEST HANDLE ON ITS PRECIPITATION...SO TRENDED THE FORECAST TOWARD IT. AS THE SYSTEM MOVES INTO OUR AREA THIS EXPECT TO SEE A GRADUAL SPLIT AS THE 850 TO 700 MB MOISTURE TRANSPORT BREAKS APART AND ONE PART GOES ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN...AND THE OTHER PIECE MOVES TO THE WEST OF OUR AREA. SO EXPECT THE AREA WHICH MOVES INTO SOUTHEAST MINNESOTA TO DISSPATE. MEANWHILE THE BETTER CHANCES OF PRECIPITATION WILL BE SOUTH OF INTERSTATE 90 AS THAT JET VEERS THROUGH THAT AREA. THERE MAY BE A REMNANT MCV THAT KEEPS SOME PRECIPITATION ACROSS WESTERN WISCONSIN THIS AFTERNOON. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 330 AM CDT SAT AUG 23 2014 SFC BOUNDARY LIES...MORE OR LESS...WEST EAST ACROSS SOUTHERN IA INTO CENTRAL ILL EARLY THIS MORNING. AN UPPER LEVEL TROUGH WILL LIFT NORTHEAST ACROSS THE NORTHERN PLAINS TODAY...AND SHOULD HELP GIVE THIS BOUNDARY A SHOVE NORTH. MEANWHILE...THERE ARE SUGGESTIONS IN THE MESO MODELS THAT AN MCV ASSOCIATED WITH THE CURRENT CONVECTION OVER NEB WOULD TAKE NORTHEAST TRACK TODAY...AND COULD SERVE AS A FOCUS FOR SHOWER/STORMS DEVELOP AS IT AND THE BOUNDARY SLIDE NORTH/NORTHEAST ACROSS THE REGION. HEAT AND HUMIDITY WILL ROUND OUT THE WEEKEND...AND HEAT ADVISORIES LOOK LIKELY FOR PORTIONS OF THE REGION. 850 MB SREF TEMP ANOMALIES AROUND +1.5 FOR SUNDAY WHILE 950 MB TEMPS ARE EXPECTED TO WARM TO 26- 28 C. HIGHS SHOULD REACH 90 ACROSS MUCH OF THE FORECAST AREA. ADD IN DEW POINTS IN THE LOWER 70S AND AFTERNOON HEAT INDICES SHOULD REACH 100 FOR A LARGE PORTION OF THE FORECAST AREA. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 330 AM CDT SAT AUG 23 2014 MODELS IN PRETTY GOOD AGREEMENT WITH THE OVERALL PATTERN THROUGH THE MIDDLE PART OF THE NEW WORK WEEK. SOLUTIONS SUGGEST AN UPPER LEVEL SHORTWAVE WILL TRACK OUT OF THE CENTRAL ROCKIES...ACROSS THE NORTHERN PLAINS AND INTO SOUTHERN CANADA SUNDAY NIGHT. ITS ASSOCIATED SFC COLD FRONT WILL DRAG ACROSS THE REGION LATE SUNDAY NIGHT INTO MONDAY...WITH THE SOUTHERN EXTENT LIKELY LINGERING IN A SOUTHWEST-NORTHEAST ORIENTATION OVER THE REGION. RIPPLES IN THE UPPER LEVEL FLOW WILL KICK OUT OF THE MEAN TROUGH...AND WORK ON THIS BOUNDARY MON-TUE. THIS NEXT TROUGH THEN SLIDES ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WED NIGHT/THU...CONTINUING TO WORK ON THAT SFC BOUNDARY...BUT ALSO PUSHING IT EAST/SOUTHEAST AS THE SYSTEM EXITS INTO THE EASTERN GREAT LAKES ON THU NIGHT. THERE ARE SOME DISCREPANCIES IN THE MODELS WITH PLACEMENT...TIMING AND STRENGTH OF THIS TROUGH...BUT THE TRENDS ARE SIMILAR AND ALL POINT TO SEVERAL DAYS WITH RAIN CHANCES. NOT OVERLY STRONG...BUT FAIRLY PERSISTENT FETCH OF 850 MB MOISTURE TRANSPORT INTO THE REGION FOR THE EARLY PART OF THE UPCOMING WEEK. WARM CLOUD DEPTHS CONTINUE TO HOVER NEAR 4 KFT WHILE PWS RANGE FROM 1.5 TO 1.75 INCHES. SO...HEAVY RAIN WOULD BE LIKELY WITH ANY THUNDERSTORMS...ESPECIALLY THE STRONGER ONES. AS FOR SEVERE POTENTIAL...AFTERNOON SBCAPES PROGGED FROM 2000-3000 J/KG PER THE GFS INTO WED...MOSTLY AROUND AND SOUTH OF THE SFC BOUNDARY. HOWEVER...WITH LOW/MID LEVEL WARMING PERSISTING...AND 700 MB TEMPS AROUND 10 C...THERE WILL BE A CAP TO DEAL WITH...AND SOME OF THIS LOW LEVEL INSTABILITY WILL NOT BE REALIZED. BUFKIT SOUNDINGS INDICATE THIS TOO. THE DEEPER...STRONGER SHEAR IS EXPECTED TO BE WELL INTO THE COLD AIR NORTH OF THE BOUNDARY...DISPLACED FROM THE STRONGER INSTABILITY. THERE IS SOME OVERLAP...SO SOME ENHANCED UPDRAFTS COULD BE SUPPORTED. OVERALL...NOT SURE THERE IS A TIME PERIOD THAT STANDS OUT FOR AN ORGANIZED SEVERE THREAT AT THIS TIME. THERE CERTAINLY COULD BE SOME SEVERE TO MARGINAL SEVERE STORMS...PERHAPS MORE PULSEY IN NATURE. MUCH DEPENDS ON BOUNDARY/SHORTWAVE INTERACTION AND TIME OF DAY. LOOK FOR UPDATES IN THE HWO FOR THE LATEST THOUGHTS ON THE DAY TO DAY SEVERE POTENTIAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 737 AM CDT SAT AUG 23 2014 KLSE WILL KEEP THE IFR STRATUS DECK THROUGH 23.13Z...AND THEN IT WILL SLOWLY RISE BECOMING MVFR BY 23.15Z AND VFR BY 23.19Z. WITH THE LINE OF CONVECTION EXPECTED TO SHEAR APART BEFORE REACHING KLSE WENT DRY FOR NOW. THE DENSE FOG AT KRST WILL GRADUALLY LIFT INTO A IFR/MVFR DECK BY 23.15Z...AND THEN THE CEILINGS WILL BECOME MVFR AND REMAIN THAT WAY THROUGH 24.00Z. IT DOES NOT LOOK THE BAND OF SHOWERS WILL BREAK UP PRIOR TO REACHING KRST...SO INCLUDED VICINITY SHOWERS BETWEEN 23.17Z AND 23.19Z. VFR CONTIONS ARE CONDITIONS ARE EXEPCTED AT BOTH SITES THIS EVENING...AND THEN THE MODELS SUGGEST DENSE FOG AGAIN. HOWEVER LOOKING AT THE WIND IN THE SOUNDINGS NOT BUYING INTO THIS...SO JUST KEPT THINGS VFR. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR WIZ017-029- 032>034-041>044-053>055-061. MN...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR MNZ079- 086>088-094>096. IA...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR IAZ010-011- 030. && $$ UPDATE...BOYNE SHORT TERM...RIECK LONG TERM....RIECK AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS ALBANY NY
422 PM EDT SAT AUG 23 2014 .SYNOPSIS... HIGH PRESSURE WILL GRADUALLY TAKE HOLD ACROSS THE REGION TONIGHT INTO SUNDAY. THIS HIGH PRESSURE SYSTEM WILL REMAIN OVER THE EASTERN SEABOARD INTO THE MIDDLE OF THE UPCOMING WEEK...BRINGING WARM AND DRY SUMMER WEATHER TO THE ALBANY FORECAST AREA. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... CLOUDS ARE HANGING TOUGH ACROSS THE FORECAST AREA THIS AFTERNOON. SURFACE WINDS ARE LIGHT AND GENERALLY FROM THE NORTHEAST. TEMPERATURES RANGE FROM THE 60S IN THE HILLS TO THE 70S IN THE VALLEYS. RADAR SHOWS A FEW VERY LIGHT SHOWERS OR SPRINKLES SCATTERED ACROSS THE AREA. LATEST 17Z RAP MODEL SHOWS LOW CLOUDS LINGERING UNTIL SHORTLY AFTER MIDNIGHT TONIGHT. HI-RES RAPID REFRESH MODEL SHOWS A SLIGHT CHANCE OF A SHOWER CONTINUING UNTIL SUNSET. THE HI-RES WRF AGREES WITH THE THREAT FOR ANY SHOWERS ENDING AFTER SUNSET. SKIES SHOULD GRADUALLY CLEAR OVERNIGHT...AND BASED ON TEMP/DEWPOINT/WINDS FORECAST OVERNIGHT...EXPECT AREAS OF FOG TO FORM IN THE VALLEYS. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... FOG AND/OR LOW CLOUDINESS WILL DISSIPATE SUNDAY MORNING LEAVING A MOSTLY SUNNY DAY. SOME AFTERNOON CLOUDS MAY DEVELOP OVER THE HIGHER TERRAIN WITH THE HEATING FROM THE SUN. MODELS HAVE THE AREA DRY TOMORROW SO KEPT POPS BELOW 15 PERCENT. HIGHS ON SUNDAY WILL RANGE FROM THE MID 70S IN THE HILLS TO LOW 80S IN THE VALLEYS. SUNDAY NIGHT...MOSTLY CLEAR SKIES AND LIGHT WINDS WILL LEAD TO THE DEVELOPMENT OF VALLEY FOG. IT IS THE BEGINNING OF FOG SEASON AND CONDITIONS LOOK GOOD AGAIN FOR VALLEY FOG FORMATION. THIS FOG WILL DISSIPATE MONDAY MORNING LEAVING A MOSTLY SUNNY AND WARM DAY. EXPECT MONDAY TO BE DRY UNDER HIGH PRESSURE. HIGHS MONDAY IN THE UPPER 70S HILLS TO MID 80S VALLEYS. && .LONG TERM /TUESDAY THROUGH SATURDAY/... HIGH PRESSURE WILL REMAIN AT ALL LEVELS OF THE ATMOSPHERE...THROUGH EARLY WEDNESDAY. THIS WILL CONTINUE OUR TRANQUIL LATE SUMMER WEATHER WITH SLIGHTLY ABOVE NORMAL TEMPERATURES ALONG WITH A GOOD DEAL OF SUNSHINE. WEDNESDAY INTO THURSDAY....IT LOOKS AS IF A WEAK COLD FRONT WILL CROSS THE REGION WITH PERHAPS A FEW SHOWERS AND THUNDERSTORMS...BUT WITH WEAK FORCING...CONVECTION COULD BE FAR AND FEW BETWEEN. THE FRONT HOWEVER...LOOKS TO GET HUNG UP SOMEWHERE OVER OUR REGION OR A LITTLE SOUTH OF IT. IT COULD COME BACK AS A WARM FRONT...WHILE PERHAPS A STRONGER COLD FRONT ATTEMPTS TO MAKE IT THROUGH ON SATURDAY OR SUNDAY WITH A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS. THE TROPICS CONTINUE TO TRY TO FLARE UP. WE COULD HAVE OUR THIRD TROPICAL NAMED STORM...WHICH WOULD BE NAMED CRISTOBAL BY SUNDAY. ALMOST ALL GUIDANCE KEEPS THIS STORM SOUTH AND EAST OF OUR REGION. HOWEVER...THERE COULD BE SOME INDIRECT IMPACTS OF THIS STORM...PERHAPS YIELDING A PREDECESSOR RAIN EVENT (PRE) OVER OR NEAR REGION NEXT WEEKEND...FOCUSED ON EITHER THE WARM OR COLD FRONT. THE TROPICAL SYSTEM COULD ALSO PUMP THE RIDGE OVER US...BLOCKING ANY COLD FRONT FROM MOVING SOUTH. BOTTOM LINE...THE EXTENDED PERIOD STARTS WARM AND DRY...BECOMING MORE UNCERTAIN WITH TIME BUT LIKELY TEMPERATURES STAYING AT OR EVEN A LITTLE ABOVE NORMAL. HUMIDITY WILL START OUT MODERATE (DEWPOINTS AROUND 60) PERHAPS CREEPING INTO THE 60S WITH TIME. LOOK FOR HIGHS GENERALLY IN THE 80S IN THE VALLEYS (75-80 HIGHER TERRAIN) THROUGHOUT THE PERIOD...LOWS WILL RANGE FROM THE UPPER 50S TO MID 60S. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... LOOKING AT VFR CONDITIONS THROUGH MOST OF THE EVENING. THEN...AS TEMPERATURES FALL TO THE FORECAST "CROSSOVER" TEMPERATURES IN THE LOWER 50S...ALONG WITH A SOMEWHAT DAMP GROUND FROM ALL THE THURSDAY AND FRIDAY/S RAINFALL...NO WIND AND INITIALLY FEW IF ANY SENSIBLE CLOUDS...FOG WILL LIKELY FORM AT ALL THE TAF SITES DURING THE OVERNIGHT PERIOD. WE BELIEVE THE FOG WILL BE MAINLY IFR (2SM BR) AT KGFL AND KPSF...BEGINNING AT 06Z AND 08Z RESPECTIVELY. AT THE TWO OTHER SITES SINCE TEMPERATURES ARE PROJECTED NOT TO GET AS LOW...WE WENT WITH MVFR MIST (3SM BR)..AFTER 08Z. WE ALSO INCLUDE IFR CIGS AT KGFL AND KGFL AS THE FOG COULD ACTUALLY GET RATHER DEEP. IT LOOKS AS IF THE FOG SHOULD BURN OFF BETWEEN 1130Z-1200Z ON SUNDAY. AFTER THAT...NO AVIATION WEATHER RELATED PROBLEMS ARE EXPECTED ON SUNDAY WITH GOOD VISIBILITY AND ONLY FEW-SCT CU AT THE 5-6KFT. THE N-NE 5-10KT SURFACE WIND SHOULD BECOME CALM TONIGHT...THEN 5-10KTS ON SATURDAY. OUTLOOK... SUNDAY NIGHT: NO OPERATIONAL IMPACT. AREAS FG. MONDAY: NO OPERATIONAL IMPACT. NO SIG WX. MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. TUESDAY: NO OPERATIONAL IMPACT. NO SIG WX. TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX. WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...TSRA. THURSDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...TSRA. && .FIRE WEATHER... RH VALUES WILL RISE TO NEAR 100 PERCENT OVERNIGHT WITH GRADUALLY CLEARING SKIES. EXPECT AREAS OF VALLEY FOG AND WIDESPREAD DEW TO FORM OVERNIGHT. WINDS WILL BE LIGHT AND VARIABLE. ON SUNDAY RH VALUES DROP TO BETWEEN 40 AND 50 PERCENT UNDER PARTLY SUNNY SKIES. WINDS WILL BE LIGHT AND FROM THE NORTHEAST. RH VALUES WILL INCREASE TO NEAR 100 PERCENT SUNDAY NIGHT WITH LIGHT AND VARIABLE WINDS. AREAS OF VALLEY FOG AND WIDESPREAD DEW WILL FORM AGAIN. WINDS WILL BE LIGHT AN VARIABLE. && .HYDROLOGY... NO HYDROLOGIC ISSUES ARE EXPECTED THROUGH THE NEXT FIVE DAYS. LITTLE PRECIPITATION IS EXPECTED. RIVER AND LAKE LEVELS WILL GRADUALLY RECEDE DURING THE PERIOD. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...SND NEAR TERM...SND SHORT TERM...SND LONG TERM...HWJIV AVIATION...HWJIV FIRE WEATHER...SND HYDROLOGY...SND
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
233 PM EDT SAT AUG 23 2014 ...HEAT ADVISORY ALL AREAS REST OF TODAY... .CURRENTLY...A SCT-BKN CU FIELD HAS DEVELOPED IN PREVAILING NWLY FLOW WITH A VERY HOT DAY ONGOING. A FEW OBS SHOW UPPER 90S AND 100 AT THIS TIME WITH A FEW HEAT INDICES OF AROUND 110 BEING REPORTED. SOME LOW LEVEL MIXING WILL CONTINUE AND HELP LIMIT HEAT INDICES SOMEWHAT. RAP SOUNDING SHOW A VERY DRY AIRMASS UNDER CLOUD BASES OVER SE GA AND MORE MOIST OVER NE FL WHERE PWATS ARE ABOUT 1.8 INCHES. A FEW SHOWERS HAVE POPPED OVER INLAND AREAS AND ALONG THE E COAST. AS EXPECTED THE E COAST SEA BREEZE IS STILL VERY NEAR THE COAST...BUT WILL CONTINUE TO MAKE A SLOW AND STEADY PROGRESS INLAND. FOR REST OF THE AFTN...ISOLD TO SCT SHOWERS AND STORMS WILL DEVELOP WITH THE BEST CHANCES GENERALLY OVER THE SRN 2/3RDS OF THE AREA. CONVECTION WILL LIKELY END BY AROUND MIDNIGHT TO 1 AM FOR MY INLAND NE FL ZONES. AN ISOLD STRONG STORM IS POSSIBLE. REST OF TONIGHT...MUGGY OVERNIGHT LOWS IN THE MID TO LOCALLY UPPER 70S WITH LIGHT WINDS. .SHORT TERM...FRONTAL BOUNDARY WILL SINK SOUTH TO NEAR FL/GA LINE BY SUNDAY AFTERNOON...THEN INTO CENTRAL FL SUNDAY NIGHT. THIS BOUNDARY WILL BE A FOCUS FOR SHOWERS/STORMS AS IT PASSES. THE BOUNDARY SHOULD REACH SE GA COUNTIES SUNDAY MORNING...THEN SINK SOUTH OF FORECAST AREA AROUND MIDNIGHT SUNDAY NIGHT. HIGH PRESSURE WILL PUSH SOUTH BEHIND THIS BOUNDARY...WHICH WILL LIMIT PRECIPITATION POTENTIAL ON MONDAY. WILL HAVE PRECIPITATION OVER NORTHEAST FLORIDA...DUE TO POSSIBLE OUTER MOISTURE BANDS FROM POTENTIAL TROPICAL SYSTEM. TEMPERATURES WILL BE A FEW DEGREES COOLER ON SUNDAY DUE TO CLOUDS AND PRECIPITATION COVERAGE. WITH INCREASING ONSHORE FLOW...MOST LOCATIONS WILL LIKELY REMAIN AT OR BELOW 90 ON MONDAY. .LONG TERM.../MONDAY NIGHT THROUGH SATURDAY/... THE FORECAST DURING THIS PERIOD WILL BE DRIVEN BY THE POTENTIAL FOR A TROPICAL SYSTEM TO FORM. AT THIS TIME...INDICATIONS CONTINUE TO BE FOR THIS SYSTEM TO PASS TO THE EAST OF THE AREA. WITH THIS...COULD HAVE PRECIPITATION OVER EASTERN COUNTIES...WITH MAINLY DRY CONDITIONS FURTHER INLAND. WITH THE FORECAST TRACK FOR THIS POTENTIAL TROPICAL SYSTEM STILL BEING UNCERTAIN...HAVE KEPT WITH CURRENT FORECAST GRIDS FOR THIS PERIOD. MAX TEMPERATURES WILL LIKELY BE A FEW DEGREES BELOW NORMAL THROUGH MID WEEK...THEN RETURN TO NEAR TO ABOVE NORMAL LATER IN THE PERIOD. && .AVIATION...INCLUDED VCSH FOR NOW FOR FL TAFS WITH VCTS BEGINNING IN A COUPLE OF HOURS. STILL LOOKS LIKE BEST CHANCE OF TSTM OCCURRING AT GNV SO INSERTED TEMPO GROUP 21Z-24Z. VFR SHOULD PREVAILING AFTER 00Z. && .MARINE...SELY WINDS THIS EVENING WILL TURN BACK TO THE W BY SUN MORNING. NORTHEAST WINDS WILL BEGIN TO INCREASE ON SUNDAY BEHIND A BACKDOOR COLD FRONT WITH AN EXTENDED PERIOD OF ONSHORE FLOW EXPECTED THROUGH THE MIDDLE OF NEXT WEEK. SMALL CRAFT ADVISORY CONDITIONS WILL BE POSSIBLE EARLY NEXT WEEK AS THE PRESSURE GRADIENT TIGHTENS WITH HIGH PRESSURE BUILDING DOWN THE COAST AND A POSSIBLE TROPICAL SYSTEM PASSING OVER THE WRN ATLC WATERS BUT LARGE UNCERTAINTY REMAINS ON THE EXACT TRACK. SEAS WILL BE DEPENDENT ON STRENGTH AND TRACK OF ANY TROPICAL SYSTEM BUT FOR NOW GIVEN THE CONSIDERABLE DEGREE OF UNCERTAINTY WE WILL CAP THE SEAS AT 7 FT. RIP CURRENTS: LOW RISK TODAY THEN MODERATE RISK EXPECTED TOMORROW AS ONSHORE FLOW DEVELOPS. && .CLIMATE... A FEW RECORD HIGHS ARE EXPECTED TO AT LEAST BE TIED TODAY. RECORD HIGHS TODAY JAX 98/1966 GNV 99/1902 AMG 99/1968 SSI 95/2006 && .PRELIMINARY POINT TEMPS/POPS... AMG 75 96 75 91 / 10 40 40 10 SSI 79 88 77 85 / 20 30 40 40 JAX 76 94 77 88 / 20 30 40 40 SGJ 76 90 78 87 / 10 20 40 40 GNV 75 95 73 88 / 30 50 50 20 OCF 75 95 74 89 / 30 50 50 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ALACHUA-BAKER- BRADFORD-CLAY-COLUMBIA-DUVAL-FLAGLER-GILCHRIST-HAMILTON- MARION-NASSAU-PUTNAM-ST JOHNS-SUWANNEE-UNION. GA...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR APPLING-ATKINSON- BACON-BRANTLEY-CHARLTON-CLINCH-COASTAL CAMDEN-COASTAL GLYNN- COFFEE-ECHOLS-INLAND CAMDEN-INLAND GLYNN-JEFF DAVIS-PIERCE- WARE-WAYNE. AM...NONE. && $$ SHASHY/STRUBLE/GUILLET
AREA FORECAST DISCUSSION
NWS POCATELLO ID
150 PM MDT SAT AUG 23 2014 .SHORT TERM...TONIGHT THROUGH TUESDAY. THE LATEST SATELLITE IMAGERY WAS SHOWING A LOW PRESSURE SYSTEM OVERHEAD WITH SEVERAL WELL DEFINED VORT FEATURES EMBEDDED IN THE FLOW. CURRENT RADAR TRENDS ARE SHOWING A RAPID INCREASE IN SHOWER ACTIVITY EARLY THIS MORNING AND CURRENTLY ANTICIPATE THIS CONTINUE AND BECOME MORE LINEARLY FOCUSED THROUGH THE AFTERNOON AS ONE OF THE EMBEDDED VORT FEATURES PLUNGES SOUTH THROUGH THE SNAKE RIVER PLAIN AND THE SURFACE WINDS BEGIN TO FORM A CONVERGENCE AREA WITH THUNDERSTORMS ACROSS THE UPPER VALLEY THAT DRIFTS SOUTH LATE THIS AFTERNOON BEFORE DISSIPATING LATER THIS EVENING AS THE UPPER LOW BEGINS TO LIFT NE INTO SRN MONTANA. ANTICIPATING A BRIEF BRAKE IN THE ACTION SUNDAY MORNING BEFORE THE NEXT PAC THROUGH DIGS INTO THE NW STATES SUNDAY AFTERNOON FURTHER WEST THAN PREVIOUS PROGS SPINNING UP A SHALLOW CLOSED LOW OVER THE NRN GREAT BASIN SUNDAY AFTERNOON/NIGHT WITH AN INCREASE IN SHOWER ACTIVITY WHICH LINGERS THROUGH MONDAY NIGHT/TUESDAY AS THE LOW SLOWLY FILLS AND GRADUALLY SWINGS EAST ALONG THE NEVADA/UTAH BORDER BEFORE EXITING EAST OF THE REGION TUESDAY EVENING. .LONG TERM...TUESDAY NIGHT THROUGH NEXT SATURDAY. DRIER AND WARMER CONDITIONS DEVELOP ACROSS SRN IDAHO WEDNESDAY THROUGH FRIDAY AS A TRANSIENT UPPER RIDGE MIGRATES EAST ACROSS THE AREA AHEAD OF THE NEXT APPROACHING PAC STORM SYSTEM. THE 12Z GFS CONTINUES TO TAP INTO THE REMNANTS OF HURRICANE MARIE AS IT LIFTS NE OUT OF THE SUB-TROPICAL ERN PACIFIC WATERS OFF THE MEXICAN COAST TO A POSITION WELL OFF THE CALIFORNIA COAST FRIDAY AHEAD OF THE INCOMING TROUGH. AS THE TROUGH MOVES INLAND SATURDAY...THE GFS BEGINS TO INTERACT WITH THE SUB-TROPICAL MOISTURE PRODUCING WIDESPREAD SHOWER ACTIVITY ACROSS IDAHO. THE 12Z ECMWF TAKES MARIE ON A MORE NWRLY TRAJECTORY PREVENTING THE INCOMING TROUGH FROM TAPPING INTO THE MOIST SUB-TROPICAL SYSTEM WITH DRIER CONSEQUENCES. WE WILL CONTINUE TO MONITOR THE MODEL TRENDS FOR ANY CHANGE IN EITHER MODEL. HUSTON && .AVIATION...UPPER LOW IS SLOWLY DRIFTING ACROSS SOUTHEAST IDAHO THIS AFTERNOON. ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE IN THE COLD CORE REGION WITH MOST OF THE STRATIFORM PRECIP WRAPPING AROUND THE LOW INTO THE SALMON/CHALLIS AREA. STARTING TO SEE CEILINGS AT KIDA LIFT FROM IFR TO MVFR...AND SHOULD SCATTER OUT IN THE EARLY AFTERNOON. HRRR SIGNALS INCREASING SHOWER ACTIVITY AROUND MID-AFTERNOON AND INTO THE EVENING AS LOW MOVES INTO THE YELLOWSTONE AREA. FORECAST SOUNDINGS FAVORING 6000 FT TO 10000 FT CEILINGS OVERNIGHT INTO TOMORROW. HINSBERGER && .FIRE WEATHER...A LITTLE LESS COVERAGE OF SHOWERS AND THUNDERSTORMS TODAY AS UPPER LOW SLOWLY DRIFTS ACROSS SOUTHEAST IDAHO TODAY. HEAVIER PRECIP IS BEING WRAPPED AROUND THE LOW INTO LEMHI COUNTY. DRIER WEATHER IS EXPECTED SUNDAY AS INFLUENCE OF LOW WANES...BUT MODELS ARE PROJECTING ANOTHER UPPER LOW TO DROP INTO OR/ID SUNDAY NIGHT. IMPULSES OF ENERGY AROUND THE LOW WILL BRING MORE SHOWERS AND THUNDERSTORMS TO THE AREA DURING THE DAY MONDAY...AND MAY LINGER INTO TUESDAY MORNING. UPPER RIDGING WILL BRING DRIER WEATHER TO THE REGION LATER ON TUESDAY AND SHOULD LAST THROUGH FRIDAY. A PACIFIC TROUGH WILL APPROACH THE WEST ON FRIDAY. REMNANTS OF HURRICANE MARIE MAY BE POSITIONED TO CONTRIBUTE ITS TROPICAL MOISTURE THOUGH THERE IS STILL SOME UNCERTAINTY WITH ITS TRACK IN RELATION TO THE PACIFIC TROUGH...BUT SIGNS POINT TO ANOTHER WET WEEKEND. HINSBERGER && .PIH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 600 PM CDT Sat Aug 23 2014 .SHORT TERM...(This evening through Sunday) ISSUED AT 319 PM CDT SAT AUG 23 2014 Southern flank of morning thunderstorm complex continues to impact the northeast KILX CWA around Champaign and Danville this afternoon, with only minimal development noted further southwest along the trailing outflow boundary. Models have once again handled the situation poorly, with the NAM/GFS being too aggressive with convective development and the HRRR keeping system too far north. Think storms will gradually push into Indiana over the next 3 to 4 hours, followed by only isolated convection across the eastern CWA early this evening. Once daytime instability wanes, dry conditions are expected overnight. With clearing skies and light winds, fog will likely develop late tonight into Sunday morning. Forecast soundings and numeric guidance both suggest at least some restriction to visibilities, and based on what happened last night, think its prudent to carry patchy fog late tonight. Upper ridge axis will continue to control the weather across central Illinois on Sunday, providing hot and mainly dry conditions. Some models are hinting that widely scattered convection may fire along the Indiana border by afternoon, but think this is a bit overdone. Will only maintain slight chance PoPs across the far southeast, with dry weather elsewhere. High temperatures will reach the lower 90s, resulting in heat index values of 100 to 105 degrees. && .LONG TERM...(Sunday night through Saturday) ISSUED AT 319 PM CDT SAT AUG 23 2014 Medium range models are generally in good agreement for the first few days of next week, then they digress pretty rapidly for two reasons. First is the difference in solutions involving the speed and strength of the upper level trough expected to move from the Rockies to Midwest. This looks like it is being caused by the second main difference, which is a lot of uncertainty with the speed and motion of a pending tropical system in the western Atlantic. These tropical systems tend to back up the west-east progression of weather systems in the middle U.S. Thus, there is a greater than normal level of uncertainty with the forecast for Wednesday through the end of the week. In the nearer term period for Monday and Tuesday, it appears likely that the hot and humid conditions will continue. Monday could end up being one of the hottest days with highs from 93-95 in central IL and 91-93 in east/southeast IL. This will keep heat index values in the 105-108 range in much of central and southeast IL, so will keep the heat advisory going through Monday. Considered extending the advisory into Tuesday, but will hold off for now since there is some level of uncertainty as to the amount of increasing cloudiness during the day, which could keep temps down just a bit. The movement of a cold front, associated with aforementioned approaching upper level trough, will really depend on the east coast tropical system. The most likely scenario, which is not really handled very well by any model, is that the front will slowly approach - and may even get hung up in central IL for a day or two. Thus, will stick with a prolonged period of scattered showers/t-storms Wednesday into Friday. The cloudiness associated with this rain potential will keep temperatures down in the 80s, ending the stretch of hot weather. However, longer term trends indicate the possibility that we may see a return to very warm conditions for Labor Day weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 600 PM CDT SAT AUG 23 2014 VFR conditions will prevail thru this evening with fog development the main forecast concern late tonight thru early Sunday morning with some MVFR and local IFR cigs and vsbys in the 10z-13z time frame, especially at CMI and BMI. Storms were occurring to the east and south of the TAF sites late this afternoon and should remain there into early this evening. A bit concerned about an outflow boundary stretching from Shelbyville northwest to just north of SPI. However, have not seen any development in that location over the past few hours with the newly developed storms further south. Any fog that does form late tonight should begin to lift between 13 and 15z with VFR conditions expected for the remainder of the period. Surface winds will be from and easterly direction at 4 to 8 kts until sunset and then a light east to southeast wind is expected after that with speeds of 5 kts or less. Southeast winds will prevail on Sunday at 10 kts or less. && .ILX WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY until 7 PM CDT Monday FOR ILZ042-047>054-056- 061>063-066>068-071>073. HEAT ADVISORY from Noon Sunday to 7 PM CDT Monday FOR ILZ036-040- 041. && $$ SHORT TERM...BARNES LONG TERM...MILLER AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
329 PM CDT SAT AUG 23 2014 .DISCUSSION... 326 PM CDT A PERSISTENT UPPER RIDGE THAT HAS BEEN SITTING OVER THE MIDWEST WILL GRADUALLY FLATTEN AND BE PUSHED TO THE SOUTH AND EAST OVER THE NEXT FEW DAYS...BUT NOT UNTIL THIS COMING THURSDAY OR FRIDAY WILL IT AND ITS SURFACE MANIFESTATION BE PUSHED FAR ENOUGH AWAY TO ALLOW A SURGE OF COOLER AND DRIER AIR INTO THE LOCAL AREA. UNTIL MIDWEEK THE WARM AND HUMID AIRMASS WILL REMAIN IN PLACE...SUPPORTING ONGOING CHANCES OF SHOWERS AND THUNDERSTORMS...WITH HEAT INDICIES ON MONDAY APPROACHING THE LOCAL HEAT ADVISORY CRITERIA OF 105F. POTENT SHORTWAVES LIFTING THROUGH THE TOP OF THE RIDGE TODAY HAVE SUPPORTED A BROAD CLUSTER OF THUNDERSTORMS WITH HEAVY RAIN. MODELS ARE IN REASONABLE AGREEMENT IN SHOWING SIMILAR BUT SOMEWHAT WEAKER WAVES LIFTING THROUGH AGAIN TOMORROW...THOUGH THE FOCUS IS A BIT FARTHER WEST. ALSO...MORE PRONOUNCED WARM ADVECTION AROUND THE 850MB LEVEL LOCALLY IS EXPECTED TO INHIBIT CONVECTIVE DEVELOPMENT COMPARED TO WHAT WE SAW TODAY...AND THE INCREASED CLOUDINESS FROM THE SHORTWAVES SHOULD ALSO SERVE TO LIMIT THE DEGREE OF AFTERNOON SURFACE HEATING. AS A WEAK SURFACE TROUGH APPROACHES SLOWLY FROM THE NORTHWEST...TSRA CHANCES CREEP BACK UP AGAIN MONDAY AND TUESDAY ALONG WITH...AND BECAUSE OF...MORE PRONOUNCED LOW LEVEL HEATING WITH SOUTH TO SOUTHWEST WINDS SUPPORTING BETTER MIXING AND A WEAKER CAP ALOFT. MONDAY LOOKS TO BE WARMER THAN EITHER SUNDAY OR TUESDAY...AND AMPLE MOISTURE WILL SUPPORT HEAT INDICIES BETWEEN 100 AND 105...NEAR THE CRITERIA FOR A HEAT ADVISORY. IT IS A BIT EARLY TO HOIST A HEADLINE BUT THIS WILL CONTINUE TO BE MONITORED. BY WEDNESDAY THE TROUGH JUST TO OUR NORTHWEST WILL HAVE EVOLVED TO A WARM FRONT ASSOCIATED WITH A LOW OVER THE PLAINS. THIS LOW THEN LIFTS ALONG THIS BOUNDARY AND SETTLES OVER THE LOCAL AREA ON THURSDAY BEFORE CONTINUING OFF TO THE EAST ON FRIDAY. HIGH TEMPERATURES BOTH WEDNESDAY AND THURSDAY COULD BE TRICKY DEPENDING ON WHERE THE SURFACE BOUNDARIES SET UP...BUT INCREASED CLOUDINESS AND ONGOING TSRA CHANCES SHOULD KEEP THOSE DAYS COOLER THAN MONDAY AND TUESDAY. THE MORE SIGNIFICANT CHANGE OF AIRMASS WILL THEN BE IN PLACE ACROSS THE ENTIRE AREA BY FRIDAY AND SATURDAY...THOUGH THE ECMWF IS A BIT SLOWER THAN THE GFS IN PUSHING THIS BOUNDARY THROUGH. LENNING && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * RAIN WITH THE CHANCE FOR A WIDELY SCATTERED LIGHTNING STRIKE THROUGH 21Z...THEN A SMALL CHANCE FOR ISOLATED SHRA/TSRA THROUGH THIS EVE. * EAST-NORTHEAST WINDS EASING IN SPEED THROUGH LATE AFTERNOON BUT REMAINING EASTERLY IN DIRECTION. * POTENTIAL FOR IFR CIGS AND/OR VISIBILITY TONIGHT INTO SUNDAY MORNING. * LAKE BREEZE TURNING WINDS EASTERLY AROUND OR POSSIBLY ABOVE 10 KT SUNDAY. //DISCUSSION...UPDATED 20Z... LINE OF STORMS HAS MOVED EAST-SOUTHEAST OF ORD AND MDW WITH STRATIFORM RAIN TO CONTINUE THROUGH 21Z. CLOUD-TO-GROUND LIGHTNING DENSITY IN THIS HAS BEEN VERY SPARSE SO HAVE OPTED NOT TO MENTION TSRA BEYOND 20Z. EASTERLY WINDS HAVE OCCASIONALLY GUSTED ON THE BACKSIDE OF THE STORMS AND SHOULD SEE A SLOW EASE IN SPEED. THE RAINFALL ALONG WITH DIMINISHING WIND SPEED GOING TO THIS EVE...LIKELY WILL LEAD TO BETTER POTENTIAL FOR FOG AND/OR STRATUS. PREV DISCUSSION...UPDATED 18Z... AREA OF SHOWERS AND STORMS CONTINUES TO MOVE EASTWARD WITH A SLOW WANING TREND...ESPECIALLY IN PART OF THE SEGMENT JUST UPSTREAM OF ORD AND MDW. WHILE THAT IS THE CASE...INCREASED CONVERGENCE BETWEEN THE OUTFLOW AND THE LAKE BREEZE IN UNCAPPED AIR WILL LIKELY SPARK MORE STORMS. THIS ALSO COULD EXTEND THE TSRA TIMING. SO FEEL COMFORTABLE WITH THE TSRA STILL INDICATED IN THE CHICAGOLAND TAFS. STRATIFORM RAIN BEHIND THIS WILL LIKELY BE ACCOMPANIED WITH MVFR CONDITIONS. SCATTERED SHOWERS AND STORMS ARE POSSIBLE BEHIND THIS DURING THE LATTER HALF OF THE AFTERNOON INTO THE EVENING IN THE CONTINUED MOISTURE RICH AIR MASS. THE WIND DIRECTION WILL LIKELY TURN SOUTHWEST AS THE STORMS PASS...AS ALL OBSERVATIONS SITES HAVE INDICATED THAT UPSTREAM AND RADAR SHOW WELL-DEFINED OUTFLOW. THE SPEED OF THE OUTFLOW HAS SLOWED SOME...SO THE DEGREE OF GUSTS AT CHICAGOLAND TAF SITES IS EXPECTED TO BE LESS THAN 30 KT. THE WIND DIRECTION BEHIND THE INITIAL PUSH OF STORMS MAY BECOME VARIABLE...BUT IS ANTICIPATED TO TURN EAST OR SOUTHEAST BASED ON THE SYNOPTIC FLOW AND CLIMATOLOGY FOR POST-THUNDERSTORM WINDS AT ORD. THE MOISTURE IN THE LOW-LEVELS AIDED BY RAIN EARLY THIS AFTERNOON WILL SET THE STAGE ONCE AGAIN FOR FOG AND LOW CIGS TONIGHT...HOWEVER THE COVERAGE OF THIS IS DIFFICULT TO DETERMINE AT THIS TIME. A LAKE BREEZE LOOKS LIKELY ON SUNDAY AFTERNOON INTO NORTHEAST ILLINOIS THAT WILL PROBABLY REACH BOTH ORD AND MDW. //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH IN RAIN END TIME. LOW IN WHETHER ANYMORE SHRA/TSRA WILL OCCUR THROUGH THIS EVE. * MEDIUM IN WIND DIRECTION AND SPEED THROUGH EARLY THIS EVE. * MEDIUM IN SOME FORM OF IFR RESTRICTION LATE TONIGHT INTO EARLY SUNDAY MORNING. LOW ON WHETHER FOG AND/OR CIG. //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MTF && .MARINE... 153 PM CDT RELATIVELY LIGHT WINDS ARE IN PLACE THIS AFTERNOON AS A WEAK PRESSURE GRADIENT IS IN PLACE ACROSS THE REGION. WINDS WILL BEGIN TO FRESHEN UP SLIGHTLY TONIGHT AND VEER TO THE SOUTHEAST AS BROAD AREA OF LOW PRESSURE OVER THE PLAINS BEGINS TO CONSOLIDATE AND DEEPEN AS IT LIFTS TOWARDS THE CANADIAN PRAIRIES. THIS LOW WILL DRAG A WEAK COLD FRONT SOUTH ACROSS LAKE MICHIGAN LATE TUESDAY INTO WEDNESDAY WITH WINDS TURNING TO THE NORTH BEHIND THROUGH THE REMAINDER OF THE WEEK. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 319 PM CDT Sat Aug 23 2014 .SHORT TERM...(This evening through Sunday) ISSUED AT 319 PM CDT SAT AUG 23 2014 Southern flank of morning thunderstorm complex continues to impact the northeast KILX CWA around Champaign and Danville this afternoon, with only minimal development noted further southwest along the trailing outflow boundary. Models have once again handled the situation poorly, with the NAM/GFS being too aggressive with convective development and the HRRR keeping system too far north. Think storms will gradually push into Indiana over the next 3 to 4 hours, followed by only isolated convection across the eastern CWA early this evening. Once daytime instability wanes, dry conditions are expected overnight. With clearing skies and light winds, fog will likely develop late tonight into Sunday morning. Forecast soundings and numeric guidance both suggest at least some restriction to visibilities, and based on what happened last night, think its prudent to carry patchy fog late tonight. Upper ridge axis will continue to control the weather across central Illinois on Sunday, providing hot and mainly dry conditions. Some models are hinting that widely scattered convection may fire along the Indiana border by afternoon, but think this is a bit overdone. Will only maintain slight chance PoPs across the far southeast, with dry weather elsewhere. High temperatures will reach the lower 90s, resulting in heat index values of 100 to 105 degrees. && .LONG TERM...(Sunday night through Saturday) ISSUED AT 319 PM CDT SAT AUG 23 2014 Medium range models are generally in good agreement for the first few days of next week, then they digress pretty rapidly for two reasons. First is the difference in solutions involving the speed and strength of the upper level trough expected to move from the Rockies to Midwest. This looks like it is being caused by the second main difference, which is a lot of uncertainty with the speed and motion of a pending tropical system in the western Atlantic. These tropical systems tend to back up the west-east progression of weather systems in the middle U.S. Thus, there is a greater than normal level of uncertainty with the forecast for Wednesday through the end of the week. In the nearer term period for Monday and Tuesday, it appears likely that the hot and humid conditions will continue. Monday could end up being one of the hottest days with highs from 93-95 in central IL and 91-93 in east/southeast IL. This will keep heat index values in the 105-108 range in much of central and southeast IL, so will keep the heat advisory going through Monday. Considered extending the advisory into Tuesday, but will hold off for now since there is some level of uncertainty as to the amount of increasing cloudiness during the day, which could keep temps down just a bit. The movement of a cold front, associated with aforementioned approaching upper level trough, will really depend on the east coast tropical system. The most likely scenario, which is not really handled very well by any model, is that the front will slowly approach - and may even get hung up in central IL for a day or two. Thus, will stick with a prolonged period of scattered showers/t-storms Wednesday into Friday. The cloudiness associated with this rain potential will keep temperatures down in the 80s, ending the stretch of hot weather. However, longer term trends indicate the possibility that we may see a return to very warm conditions for Labor Day weekend. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) ISSUED AT 1236 PM CDT SAT AUG 23 2014 Southern flank of storm complex tracking across northern Illinois is skirting along the I-74 corridor early this afternoon. Storms have already impacted KPIA with heavy rain and gusty winds up to around 25kt and will push through KBMI over the next hour. Still some question whether they will hold together and reach far enough south to impact KCMI, so have only gone with VCTS there. Elsewhere around the area, will maintain dry conditions through the afternoon. Once convection exits into Indiana, skies will gradually clear by this evening. Due to light winds and very high dewpoints, think fog will once again develop across the area overnight. Have therefore included restricted visbys down to between 2 and 4 miles between 09z and 14z. && .ILX WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY until 7 PM CDT Monday FOR ILZ042-047>054-056- 061>063-066>068-071>073. HEAT ADVISORY from Noon Sunday to 7 PM CDT Monday FOR ILZ036-040- 041. && $$ SHORT TERM...BARNES LONG TERM...MILLER AVIATION...BARNES
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
304 PM CDT SAT AUG 23 2014 .MESOSCALE DISCUSSION... 115 PM CDT LINE OF STORMS IS MOVING EAST INTO THE CHICAGOLAND AREA EARLY THIS AFTERNOON. WHILE THIS HAS SHOWN A GRADUAL WEAKENING TREND WITH LESS LIGHTNING...DESTABILIZATION ACROSS NORTHWEST IN...EASTERN IL...AND INTO THE SOUTH CHICAGO METRO THE PAST FEW HOURS SHOULD AID IN THE ACTIVITY TO AT LEAST PERSIST WITH HEAVY RAINFALL RATES. IN ADDITION...CONVERGENCE FROM THE SYSTEM OUTFLOW AND THE LAKE BREEZE HAS ALREADY FIRED A FEW ADDITIONAL CELLS AND THAT WILL LIKELY CONTINUE TO OCCUR IN SUBURBAN AREAS THROUGH 2-3 PM. THE AREA OF STORMS ALSO SHOULD FURTHER SLOW AS IT RUNS INTO THE MARINE LAYER. THIS MAY CAUSE HEAVY RAINFALL RATES TO PERSIST OVER THE SAME URBAN AREAS FOR A WHILE...INCLUDING THOSE THAT WERE HIT HARD LATE THURSDAY NIGHT. WILL BE MONITORING CLOSELY. SEVERE THREAT APPEARS MINIMAL...WITH MAINLY THE FAR SOUTHEAST CWA BEING THE ONE AREA THAT COULD SEE AN ISOLATED FLARE UP TO THAT LEVEL. NOW THAT AREAS HAVE BEEN RAIN COOLED...WILL ADJUST TEMPERATURES CONSIDERABLY DOWNWARD THE REST OF THE AFTERNOON. MTF && .DISCUSSION... 959 AM CDT THE FORECAST HAS BEEN UPDATED TO REFLECT GREATER CLOUD COVER AREAWIDE AND HIGHER POPS ACROSS MAINLY NORTH CENTRAL ILLINOIS DURING THE EARLY-MID AFTERNOON. A BROAD MESOSCALE CONVECTIVE SYSTEM WITH A LINE OF STORMS ON ITS FRONT EDGE IS CURRENTLY ADVANCING EAST OVER THE MISSISSIPPI RIVER AND FAR WESTERN ILLINOIS. THIS CONTINUES TO HOLD TOGETHER WELL WITH ONLY SUBTLE CLOUD TOP WARMING AND NO FADE IN LIGHTNING ACTIVITY OVER THE PAST COUPLE HOURS. THIS COMPLEX HAS BEEN ONGOING FOR OVER NINE HOURS SO NOT SURPRISED TO SEE THAT THE RADAR LOOP INDICATES THE LIKELY PRESENCE OF A CONVECTIVELY-INDUCED VORTICITY MAXIMUM /MCV/ IN FAR EASTERN IA. THIS WITH A COLD POOL IS HELPING TO USHER PUSH THE STORMS MORE EASTWARD THAN THE NORTHEAST MOVEMENT OF THE PARENT SHORTWAVE WOULD INDICATE. DESPITE WHAT SHOULD BE A GRADUAL FACE INTO THE EARLY AFTERNOON WITH THE UPPER SUPPORT MOVING NORTHEAST AND A DECAYING LOW-LEVEL JET PER PROFILERS...2.2 INCH PWAT AIR /99TH PERCENTILE/ AHEAD OF THE MCV WILL LIKELY SUPPORT SHOWERS AND SOME STORMS INTO NORTH CENTRAL ILLINOIS BETWEEN NOON AND 3 PM. STILL SEEING SOME EMBEDDED HOURLY PRECIP REPORTS OF A HALF TO ONE INCH WITH THIS...AND SOME OF THIS EFFICIENCY COULD CERTAINLY OCCUR ALONG AND WEST OF I-39 DURING THE EARLY AFTERNOON. UNDER THE INFLUENCE OF WEAK UPPER LEVEL FLOW...THE MCV IS FORECAST BY THE RAP AND NAM TO CONTINUE TO SLOW AS IT MOVES INTO NORTH CENTRAL IL. DESTABILIZATION AHEAD OF IT MAY SUPPORT ISOLATED OR SCATTERED SHOWERS/STORMS LATER THIS AFTERNOON FURTHER EAST TOWARD CHICAGO AND THE I-57 CORRIDOR INTO NORTHWEST INDIANA...BUT CONFIDENCE ON THIS IS LOW AS ANVIL SHIELD WILL INHIBIT THE RATE OF WARMTH...WITH MOST GUIDANCE INDICATING THE PRESENCE OF A CAP AND LOW-LEVEL FLOW OFF THE LAKE IN FAR NORTHEAST IL. MINOR TWEAKS MADE TO HOURLY TEMPERATURES AND DEW POINTS. MTF //PREV DISCUSSION... 327 AM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES/TIMING THROUGH THE PERIOD ALONG WITH HIGH TEMPERATURES/HEAT INDICES THROUGH MONDAY. AREAS OF FOG CONTINUE TO DEVELOP WITH VISIBILITIES DROPPING UNDER 1SM IN A FEW LOCATIONS. NOT EXPECTING WIDESPREAD DENSE FOG THIS MORNING BUT WILL NEED TO MONITOR OBS OVER THE NEXT FEW HOURS. THE FOG WILL LIFT THIS MORNING BUT WITH LITTLE CHANGE TO THE AIRMASS FOG WILL BE POSSIBLE AGAIN TONIGHT INTO SUNDAY MORNING. A FEW SHOWERS DEVELOPED ACROSS NORTHERN LAKE COUNTY IN NORTHEAST IL LATE FRIDAY EVENING AND PERSISTED FOR A FEW HOURS BEFORE DISSIPATING. OTHERWISE...CONVECTION HAS BEEN FOCUSED FURTHER WEST EARLY THIS MORNING IN THE VICINITY OF THE LOW LEVEL JET. SOME OF THIS ACTIVITY OVER EASTERN IA MAY ARRIVE ACROSS THE WESTERN CWA LATER THIS MORNING...LIKELY IN A DECAYING FORM. BUT OTHER THAN AN ISOLATED SHOWER...EXPECT THE NEXT SEVERAL HOURS TO BE MAINLY DRY. CONFIDENCE REGARDING THUNDERSTORM CHANCES THIS AFTERNOON INTO THIS EVENING IS LOW THOUGH THERE IS SOME CONSENSUS FOR DEVELOPMENT BY EARLY AFTERNOON ACROSS WESTERN/NORTHWEST IL FROM REMNANTS OF CONVECTION OVER EASTERN NEBRASKA/WESTERN IA. HOW FAR IT CONTINUES EAST OR NORTHEAST BEFORE WEAKENING IS ANOTHER UNCERTAINTY. MADE NO SIGNIFICANT CHANGES FOR TODAY MAINTAINING 30-40 POPS. TRENDS WILL NEED TO BE MONITORED THRU THE MORNING. DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES APPROACHING 2 INCHES WILL LEAD TO VERY HEAVY RAIN WITH ANY THUNDERSTORMS THAT DO DEVELOP AND POSSIBLY FLASH FLOODING...ESPECIALLY IF THE RAIN FALLS OVER HARDER HIT AREAS FROM FRIDAY MORNING. THE UPPER RIDGE THEN BUILDS ACROSS THE AREA TONIGHT AND SUNDAY AND PRECIP CHANCES LOOK BELOW MENTIONABLE FROM LATE TONIGHT THROUGH MONDAY MORNING. CAN/T COMPLETELY RULE OUT SOME ISOLATED ACTIVITY... IN PARTICULAR ON A LAKE BREEZE SUNDAY AFTERNOON. A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY WITH SOME DIFFERENCES AS TO HOW FAR SOUTH THIS BOUNDARY WILL SETTLE MONDAY AFTERNOON INTO MONDAY NIGHT. THIS WOULD LIKELY BE THE NEXT CHANCE OF THUNDERSTORMS WITH THE GEM/ECMWF BOTH PUSHING THE FRONT THROUGH MUCH OF THE CWA BY TUESDAY MORNING. THIS BOUNDARY THEN MEANDERS NEAR THE IL/WI BORDER INTO THURSDAY WITH THE POSSIBILITY OF A PROLONGED UNSETTLED PATTERN ACROSS THE AREA. CLOUD COVER/CONVECTION TODAY WILL LIKELY KEEP TEMPS IN THE 80S... THOUGH WITH THE URBAN AREAS STARTING FROM LOWER/MID 70S...ANY LONGER PERIOD OF SUNSHINE TODAY COULD ALLOW A FEW PLACES TO TAG 90. TEMPS WILL WARM A FEW DEGREES SUNDAY BUT SOUTHEASTERLY WINDS WILL KEEP THE LAKESHORE COOLER. MONDAY LOOKS TO BE THE BEST CHANCE FOR TEMPS INTO THE LOWER 90S CWA WIDE BUT WILL BE DEPENDENT ON CLOUD COVER AND TIMING/ARRIVAL OF ANY PRECIP. DEWPOINTS MAY LOWER A FEW DEGREES...BACK INTO THE MID/UPPER 60S ACROSS PARTS OF THE AREA SUNDAY. HEAT INDICES COULD RANGE FROM LOWER/MID 90S TO 100-105 FAR SOUTHWEST. DEWPOINTS THEN BACK INTO THE 70S EVERYWHERE MONDAY WITH HEAT INDICES CLOSER TO 100-105 MOST AREAS WITH STILL THE POTENTIAL TO REACH HEAT ADVISORY CRITERIA ACROSS THE FAR SOUTHERN CWA MONDAY AFTERNOON. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * RAIN WITH THE CHANCE FOR A WIDELY SCATTERED LIGHTNING STRIKE THROUGH 21Z...THEN A SMALL CHANCE FOR ISOLATED SHRA/TSRA THROUGH THIS EVE. * EAST-NORTHEAST WINDS EASING IN SPEED THROUGH LATE AFTERNOON BUT REMAINING EASTERLY IN DIRECTION. * POTENTIAL FOR IFR CIGS AND/OR VISIBILITY TONIGHT INTO SUNDAY MORNING. * LAKE BREEZE TURNING WINDS EASTERLY AROUND OR POSSIBLY ABOVE 10 KT SUNDAY. //DISCUSSION...UPDATED 20Z... LINE OF STORMS HAS MOVED EAST-SOUTHEAST OF ORD AND MDW WITH STRATIFORM RAIN TO CONTINUE THROUGH 21Z. CLOUD-TO-GROUND LIGHTNING DENSITY IN THIS HAS BEEN VERY SPARSE SO HAVE OPTED NOT TO MENTION TSRA BEYOND 20Z. EASTERLY WINDS HAVE OCCASIONALLY GUSTED ON THE BACKSIDE OF THE STORMS AND SHOULD SEE A SLOW EASE IN SPEED. THE RAINFALL ALONG WITH DIMINISHING WIND SPEED GOING TO THIS EVE...LIKELY WILL LEAD TO BETTER POTENTIAL FOR FOG AND/OR STRATUS. PREV DISCUSSION...UPDATED 18Z... AREA OF SHOWERS AND STORMS CONTINUES TO MOVE EASTWARD WITH A SLOW WANING TREND...ESPECIALLY IN PART OF THE SEGMENT JUST UPSTREAM OF ORD AND MDW. WHILE THAT IS THE CASE...INCREASED CONVERGENCE BETWEEN THE OUTFLOW AND THE LAKE BREEZE IN UNCAPPED AIR WILL LIKELY SPARK MORE STORMS. THIS ALSO COULD EXTEND THE TSRA TIMING. SO FEEL COMFORTABLE WITH THE TSRA STILL INDICATED IN THE CHICAGOLAND TAFS. STRATIFORM RAIN BEHIND THIS WILL LIKELY BE ACCOMPANIED WITH MVFR CONDITIONS. SCATTERED SHOWERS AND STORMS ARE POSSIBLE BEHIND THIS DURING THE LATTER HALF OF THE AFTERNOON INTO THE EVENING IN THE CONTINUED MOISTURE RICH AIR MASS. THE WIND DIRECTION WILL LIKELY TURN SOUTHWEST AS THE STORMS PASS...AS ALL OBSERVATIONS SITES HAVE INDICATED THAT UPSTREAM AND RADAR SHOW WELL-DEFINED OUTFLOW. THE SPEED OF THE OUTFLOW HAS SLOWED SOME...SO THE DEGREE OF GUSTS AT CHICAGOLAND TAF SITES IS EXPECTED TO BE LESS THAN 30 KT. THE WIND DIRECTION BEHIND THE INITIAL PUSH OF STORMS MAY BECOME VARIABLE...BUT IS ANTICIPATED TO TURN EAST OR SOUTHEAST BASED ON THE SYNOPTIC FLOW AND CLIMATOLOGY FOR POST-THUNDERSTORM WINDS AT ORD. THE MOISTURE IN THE LOW-LEVELS AIDED BY RAIN EARLY THIS AFTERNOON WILL SET THE STAGE ONCE AGAIN FOR FOG AND LOW CIGS TONIGHT...HOWEVER THE COVERAGE OF THIS IS DIFFICULT TO DETERMINE AT THIS TIME. A LAKE BREEZE LOOKS LIKELY ON SUNDAY AFTERNOON INTO NORTHEAST ILLINOIS THAT WILL PROBABLY REACH BOTH ORD AND MDW. //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH IN RAIN END TIME. LOW IN WHETHER ANYMORE SHRA/TSRA WILL OCCUR THROUGH THIS EVE. * MEDIUM IN WIND DIRECTION AND SPEED THROUGH EARLY THIS EVE. * MEDIUM IN SOME FORM OF IFR RESTRICTION LATE TONIGHT INTO EARLY SUNDAY MORNING. LOW ON WHETHER FOG AND/OR CIG. //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MTF && .MARINE... 153 PM CDT RELATIVELY LIGHT WINDS ARE IN PLACE THIS AFTERNOON AS A WEAK PRESSURE GRADIENT IS IN PLACE ACROSS THE REGION. WINDS WILL BEGIN TO FRESHEN UP SLIGHTLY TONIGHT AND VEER TO THE SOUTHEAST AS BROAD AREA OF LOW PRESSURE OVER THE PLAINS BEGINS TO CONSOLIDATE AND DEEPEN AS IT LIFTS TOWARDS THE CANADIAN PRAIRIES. THIS LOW WILL DRAG A WEAK COLD FRONT SOUTH ACROSS LAKE MICHIGAN LATE TUESDAY INTO WEDNESDAY WITH WINDS TURNING TO THE NORTH BEHIND THROUGH THE REMAINDER OF THE WEEK. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...DENSE FOG ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
154 PM CDT SAT AUG 23 2014 .MESOSCALE DISCUSSION... 115 PM CDT LINE OF STORMS IS MOVING EAST INTO THE CHICAGOLAND AREA EARLY THIS AFTERNOON. WHILE THIS HAS SHOWN A GRADUAL WEAKENING TREND WITH LESS LIGHTNING...DESTABILIZATION ACROSS NORTHWEST IN...EASTERN IL...AND INTO THE SOUTH CHICAGO METRO THE PAST FEW HOURS SHOULD AID IN THE ACTIVITY TO AT LEAST PERSIST WITH HEAVY RAINFALL RATES. IN ADDITION...CONVERGENCE FROM THE SYSTEM OUTFLOW AND THE LAKE BREEZE HAS ALREADY FIRED A FEW ADDITIONAL CELLS AND THAT WILL LIKELY CONTINUE TO OCCUR IN SUBURBAN AREAS THROUGH 2-3 PM. THE AREA OF STORMS ALSO SHOULD FURTHER SLOW AS IT RUNS INTO THE MARINE LAYER. THIS MAY CAUSE HEAVY RAINFALL RATES TO PERSIST OVER THE SAME URBAN AREAS FOR A WHILE...INCLUDING THOSE THAT WERE HIT HARD LATE THURSDAY NIGHT. WILL BE MONITORING CLOSELY. SEVERE THREAT APPEARS MINIMAL...WITH MAINLY THE FAR SOUTHEAST CWA BEING THE ONE AREA THAT COULD SEE AN ISOLATED FLARE UP TO THAT LEVEL. NOW THAT AREAS HAVE BEEN RAIN COOLED...WILL ADJUST TEMPERATURES CONSIDERABLY DOWNWARD THE REST OF THE AFTERNOON. MTF && .DISCUSSION... 959 AM CDT THE FORECAST HAS BEEN UPDATED TO REFLECT GREATER CLOUD COVER AREAWIDE AND HIGHER POPS ACROSS MAINLY NORTH CENTRAL ILLINOIS DURING THE EARLY-MID AFTERNOON. A BROAD MESOSCALE CONVECTIVE SYSTEM WITH A LINE OF STORMS ON ITS FRONT EDGE IS CURRENTLY ADVANCING EAST OVER THE MISSISSIPPI RIVER AND FAR WESTERN ILLINOIS. THIS CONTINUES TO HOLD TOGETHER WELL WITH ONLY SUBTLE CLOUD TOP WARMING AND NO FADE IN LIGHTNING ACTIVITY OVER THE PAST COUPLE HOURS. THIS COMPLEX HAS BEEN ONGOING FOR OVER NINE HOURS SO NOT SURPRISED TO SEE THAT THE RADAR LOOP INDICATES THE LIKELY PRESENCE OF A CONVECTIVELY-INDUCED VORTICITY MAXIMUM /MCV/ IN FAR EASTERN IA. THIS WITH A COLD POOL IS HELPING TO USHER PUSH THE STORMS MORE EASTWARD THAN THE NORTHEAST MOVEMENT OF THE PARENT SHORTWAVE WOULD INDICATE. DESPITE WHAT SHOULD BE A GRADUAL FACE INTO THE EARLY AFTERNOON WITH THE UPPER SUPPORT MOVING NORTHEAST AND A DECAYING LOW-LEVEL JET PER PROFILERS...2.2 INCH PWAT AIR /99TH PERCENTILE/ AHEAD OF THE MCV WILL LIKELY SUPPORT SHOWERS AND SOME STORMS INTO NORTH CENTRAL ILLINOIS BETWEEN NOON AND 3 PM. STILL SEEING SOME EMBEDDED HOURLY PRECIP REPORTS OF A HALF TO ONE INCH WITH THIS...AND SOME OF THIS EFFICIENCY COULD CERTAINLY OCCUR ALONG AND WEST OF I-39 DURING THE EARLY AFTERNOON. UNDER THE INFLUENCE OF WEAK UPPER LEVEL FLOW...THE MCV IS FORECAST BY THE RAP AND NAM TO CONTINUE TO SLOW AS IT MOVES INTO NORTH CENTRAL IL. DESTABILIZATION AHEAD OF IT MAY SUPPORT ISOLATED OR SCATTERED SHOWERS/STORMS LATER THIS AFTERNOON FURTHER EAST TOWARD CHICAGO AND THE I-57 CORRIDOR INTO NORTHWEST INDIANA...BUT CONFIDENCE ON THIS IS LOW AS ANVIL SHIELD WILL INHIBIT THE RATE OF WARMTH...WITH MOST GUIDANCE INDICATING THE PRESENCE OF A CAP AND LOW-LEVEL FLOW OFF THE LAKE IN FAR NORTHEAST IL. MINOR TWEAKS MADE TO HOURLY TEMPERATURES AND DEW POINTS. MTF //PREV DISCUSSION... 327 AM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES/TIMING THROUGH THE PERIOD ALONG WITH HIGH TEMPERATURES/HEAT INDICES THROUGH MONDAY. AREAS OF FOG CONTINUE TO DEVELOP WITH VISIBILITIES DROPPING UNDER 1SM IN A FEW LOCATIONS. NOT EXPECTING WIDESPREAD DENSE FOG THIS MORNING BUT WILL NEED TO MONITOR OBS OVER THE NEXT FEW HOURS. THE FOG WILL LIFT THIS MORNING BUT WITH LITTLE CHANGE TO THE AIRMASS FOG WILL BE POSSIBLE AGAIN TONIGHT INTO SUNDAY MORNING. A FEW SHOWERS DEVELOPED ACROSS NORTHERN LAKE COUNTY IN NORTHEAST IL LATE FRIDAY EVENING AND PERSISTED FOR A FEW HOURS BEFORE DISSIPATING. OTHERWISE...CONVECTION HAS BEEN FOCUSED FURTHER WEST EARLY THIS MORNING IN THE VICINITY OF THE LOW LEVEL JET. SOME OF THIS ACTIVITY OVER EASTERN IA MAY ARRIVE ACROSS THE WESTERN CWA LATER THIS MORNING...LIKELY IN A DECAYING FORM. BUT OTHER THAN AN ISOLATED SHOWER...EXPECT THE NEXT SEVERAL HOURS TO BE MAINLY DRY. CONFIDENCE REGARDING THUNDERSTORM CHANCES THIS AFTERNOON INTO THIS EVENING IS LOW THOUGH THERE IS SOME CONSENSUS FOR DEVELOPMENT BY EARLY AFTERNOON ACROSS WESTERN/NORTHWEST IL FROM REMNANTS OF CONVECTION OVER EASTERN NEBRASKA/WESTERN IA. HOW FAR IT CONTINUES EAST OR NORTHEAST BEFORE WEAKENING IS ANOTHER UNCERTAINTY. MADE NO SIGNIFICANT CHANGES FOR TODAY MAINTAINING 30-40 POPS. TRENDS WILL NEED TO BE MONITORED THRU THE MORNING. DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES APPROACHING 2 INCHES WILL LEAD TO VERY HEAVY RAIN WITH ANY THUNDERSTORMS THAT DO DEVELOP AND POSSIBLY FLASH FLOODING...ESPECIALLY IF THE RAIN FALLS OVER HARDER HIT AREAS FROM FRIDAY MORNING. THE UPPER RIDGE THEN BUILDS ACROSS THE AREA TONIGHT AND SUNDAY AND PRECIP CHANCES LOOK BELOW MENTIONABLE FROM LATE TONIGHT THROUGH MONDAY MORNING. CAN/T COMPLETELY RULE OUT SOME ISOLATED ACTIVITY... IN PARTICULAR ON A LAKE BREEZE SUNDAY AFTERNOON. A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY WITH SOME DIFFERENCES AS TO HOW FAR SOUTH THIS BOUNDARY WILL SETTLE MONDAY AFTERNOON INTO MONDAY NIGHT. THIS WOULD LIKELY BE THE NEXT CHANCE OF THUNDERSTORMS WITH THE GEM/ECMWF BOTH PUSHING THE FRONT THROUGH MUCH OF THE CWA BY TUESDAY MORNING. THIS BOUNDARY THEN MEANDERS NEAR THE IL/WI BORDER INTO THURSDAY WITH THE POSSIBILITY OF A PROLONGED UNSETTLED PATTERN ACROSS THE AREA. CLOUD COVER/CONVECTION TODAY WILL LIKELY KEEP TEMPS IN THE 80S... THOUGH WITH THE URBAN AREAS STARTING FROM LOWER/MID 70S...ANY LONGER PERIOD OF SUNSHINE TODAY COULD ALLOW A FEW PLACES TO TAG 90. TEMPS WILL WARM A FEW DEGREES SUNDAY BUT SOUTHEASTERLY WINDS WILL KEEP THE LAKESHORE COOLER. MONDAY LOOKS TO BE THE BEST CHANCE FOR TEMPS INTO THE LOWER 90S CWA WIDE BUT WILL BE DEPENDENT ON CLOUD COVER AND TIMING/ARRIVAL OF ANY PRECIP. DEWPOINTS MAY LOWER A FEW DEGREES...BACK INTO THE MID/UPPER 60S ACROSS PARTS OF THE AREA SUNDAY. HEAT INDICES COULD RANGE FROM LOWER/MID 90S TO 100-105 FAR SOUTHWEST. DEWPOINTS THEN BACK INTO THE 70S EVERYWHERE MONDAY WITH HEAT INDICES CLOSER TO 100-105 MOST AREAS WITH STILL THE POTENTIAL TO REACH HEAT ADVISORY CRITERIA ACROSS THE FAR SOUTHERN CWA MONDAY AFTERNOON. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * RAIN WITH A PERIOD OF THUNDER AND POSSIBLE IFR VISIBILITY BETWEEN 19Z-21Z...WITH THE POTENTIAL FOR LINGERING SCATTERED SHRA/TSRA INTO THE EVE. * EAST-NORTHEAST WINDS SHIFTING SOUTHWEST WITH SHOWERS AND STORMS THEN LIKELY BECOMING SOUTHEAST OR EAST AFTERWARD /NEAR 20Z/ AND POTENTIALLY BEING AROUND 10 KT. * POTENTIAL FOR IFR CIGS AND/OR VISIBILITY TONIGHT INTO SUNDAY MORNING. * LAKE BREEZE TURNING WINDS EASTERLY AROUND OR POSSIBLY ABOVE 10 KT SUNDAY. //DISCUSSION...UPDATED 18Z... AREA OF SHOWERS AND STORMS CONTINUES TO MOVE EASTWARD WITH A SLOW WANING TREND...ESPECIALLY IN PART OF THE SEGMENT JUST UPSTREAM OF ORD AND MDW. WHILE THAT IS THE CASE...INCREASED CONVERGENCE BETWEEN THE OUTFLOW AND THE LAKE BREEZE IN UNCAPPED AIR WILL LIKELY SPARK MORE STORMS. THIS ALSO COULD EXTEND THE TSRA TIMING. SO FEEL COMFORTABLE WITH THE TSRA STILL INDICATED IN THE CHICAGOLAND TAFS. STRATIFORM RAIN BEHIND THIS WILL LIKELY BE ACCOMPANIED WITH MVFR CONDITIONS. SCATTERED SHOWERS AND STORMS ARE POSSIBLE BEHIND THIS DURING THE LATTER HALF OF THE AFTERNOON INTO THE EVENING IN THE CONTINUED MOISTURE RICH AIR MASS. THE WIND DIRECTION WILL LIKELY TURN SOUTHWEST AS THE STORMS PASS...AS ALL OBSERVATIONS SITES HAVE INDICATED THAT UPSTREAM AND RADAR SHOW WELL-DEFINED OUTFLOW. THE SPEED OF THE OUTFLOW HAS SLOWED SOME...SO THE DEGREE OF GUSTS AT CHICAGOLAND TAF SITES IS EXPECTED TO BE LESS THAN 30 KT. THE WIND DIRECTION BEHIND THE INITIAL PUSH OF STORMS MAY BECOME VARIABLE...BUT IS ANTICIPATED TO TURN EAST OR SOUTHEAST BASED ON THE SYNOPTIC FLOW AND CLIMATOLOGY FOR POST-THUNDERSTORM WINDS AT ORD. THE MOISTURE IN THE LOW-LEVELS AIDED BY RAIN EARLY THIS AFTERNOON WILL SET THE STAGE ONCE AGAIN FOR FOG AND LOW CIGS TONIGHT...HOWEVER THE COVERAGE OF THIS IS DIFFICULT TO DETERMINE AT THIS TIME. A LAKE BREEZE LOOKS LIKELY ON SUNDAY AFTERNOON INTO NORTHEAST ILLINOIS THAT WILL PROBABLY REACH BOTH ORD AND MDW. //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH IN THUNDER OCCURRING. MEDIUM IN DURATION. LOW IN SHRA/TSRA CHANCES THIS EVE. * LOW IN WIND DIRECTION BETWEEN 19Z AND 21Z...MEDIUM IN WIND CONDITIONS OTHERWISE...INCLUDING LAKE BREEZE TIMING ON SUNDAY. * MEDIUM IN SOME FORM OF IFR RESTRICTION LATE TONIGHT INTO EARLY SUNDAY MORNING. LOW ON WHETHER FOG AND/OR CIG. //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MTF && .MARINE... 153 PM CDT RELATIVELY LIGHT WINDS ARE IN PLACE THIS AFTERNOON AS A WEAK PRESSURE GRADIENT IS IN PLACE ACROSS THE REGION. WINDS WILL BEGIN TO FRESHEN UP SLIGHTLY TONIGHT AND VEER TO THE SOUTHEAST AS BROAD AREA OF LOW PRESSURE OVER THE PLAINS BEGINS TO CONSOLIDATE AND DEEPEN AS IT LIFTS TOWARDS THE CANADIAN PRAIRIES. THIS LOW WILL DRAG A WEAK COLD FRONT SOUTH ACROSS LAKE MICHIGAN LATE TUESDAY INTO WEDNESDAY WITH WINDS TURNING TO THE NORTH BEHIND THROUGH THE REMAINDER OF THE WEEK. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...DENSE FOG ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
117 PM CDT SAT AUG 23 2014 .MESOSCALE DISCUSSION... 115 PM CDT LINE OF STORMS IS MOVING EAST INTO THE CHICAGOLAND AREA EARLY THIS AFTERNOON. WHILE THIS HAS SHOWN A GRADUAL WEAKENING TREND WITH LESS LIGHTNING...DESTABILIZATION ACROSS NORTHWEST IN...EASTERN IL...AND INTO THE SOUTH CHICAGO METRO THE PAST FEW HOURS SHOULD AID IN THE ACTIVITY TO AT LEAST PERSIST WITH HEAVY RAINFALL RATES. IN ADDITION...CONVERGENCE FROM THE SYSTEM OUTFLOW AND THE LAKE BREEZE HAS ALREADY FIRED A FEW ADDITIONAL CELLS AND THAT WILL LIKELY CONTINUE TO OCCUR IN SUBURBAN AREAS THROUGH 2-3 PM. THE AREA OF STORMS ALSO SHOULD FURTHER SLOW AS IT RUNS INTO THE MARINE LAYER. THIS MAY CAUSE HEAVY RAINFALL RATES TO PERSIST OVER THE SAME URBAN AREAS FOR A WHILE...INCLUDING THOSE THAT WERE HIT HARD LATE THURSDAY NIGHT. WILL BE MONITORING CLOSELY. SEVERE THREAT APPEARS MINIMAL...WITH MAINLY THE FAR SOUTHEAST CWA BEING THE ONE AREA THAT COULD SEE AN ISOLATED FLARE UP TO THAT LEVEL. NOW THAT AREAS HAVE BEEN RAIN COOLED...WILL ADJUST TEMPERATURES CONSIDERABLY DOWNWARD THE REST OF THE AFTERNOON. MTF && .DISCUSSION... 959 AM CDT THE FORECAST HAS BEEN UPDATED TO REFLECT GREATER CLOUD COVER AREAWIDE AND HIGHER POPS ACROSS MAINLY NORTH CENTRAL ILLINOIS DURING THE EARLY-MID AFTERNOON. A BROAD MESOSCALE CONVECTIVE SYSTEM WITH A LINE OF STORMS ON ITS FRONT EDGE IS CURRENTLY ADVANCING EAST OVER THE MISSISSIPPI RIVER AND FAR WESTERN ILLINOIS. THIS CONTINUES TO HOLD TOGETHER WELL WITH ONLY SUBTLE CLOUD TOP WARMING AND NO FADE IN LIGHTNING ACTIVITY OVER THE PAST COUPLE HOURS. THIS COMPLEX HAS BEEN ONGOING FOR OVER NINE HOURS SO NOT SURPRISED TO SEE THAT THE RADAR LOOP INDICATES THE LIKELY PRESENCE OF A CONVECTIVELY-INDUCED VORTICITY MAXIMUM /MCV/ IN FAR EASTERN IA. THIS WITH A COLD POOL IS HELPING TO USHER PUSH THE STORMS MORE EASTWARD THAN THE NORTHEAST MOVEMENT OF THE PARENT SHORTWAVE WOULD INDICATE. DESPITE WHAT SHOULD BE A GRADUAL FACE INTO THE EARLY AFTERNOON WITH THE UPPER SUPPORT MOVING NORTHEAST AND A DECAYING LOW-LEVEL JET PER PROFILERS...2.2 INCH PWAT AIR /99TH PERCENTILE/ AHEAD OF THE MCV WILL LIKELY SUPPORT SHOWERS AND SOME STORMS INTO NORTH CENTRAL ILLINOIS BETWEEN NOON AND 3 PM. STILL SEEING SOME EMBEDDED HOURLY PRECIP REPORTS OF A HALF TO ONE INCH WITH THIS...AND SOME OF THIS EFFICIENCY COULD CERTAINLY OCCUR ALONG AND WEST OF I-39 DURING THE EARLY AFTERNOON. UNDER THE INFLUENCE OF WEAK UPPER LEVEL FLOW...THE MCV IS FORECAST BY THE RAP AND NAM TO CONTINUE TO SLOW AS IT MOVES INTO NORTH CENTRAL IL. DESTABILIZATION AHEAD OF IT MAY SUPPORT ISOLATED OR SCATTERED SHOWERS/STORMS LATER THIS AFTERNOON FURTHER EAST TOWARD CHICAGO AND THE I-57 CORRIDOR INTO NORTHWEST INDIANA...BUT CONFIDENCE ON THIS IS LOW AS ANVIL SHIELD WILL INHIBIT THE RATE OF WARMTH...WITH MOST GUIDANCE INDICATING THE PRESENCE OF A CAP AND LOW-LEVEL FLOW OFF THE LAKE IN FAR NORTHEAST IL. MINOR TWEAKS MADE TO HOURLY TEMPERATURES AND DEW POINTS. MTF //PREV DISCUSSION... 327 AM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES/TIMING THROUGH THE PERIOD ALONG WITH HIGH TEMPERATURES/HEAT INDICES THROUGH MONDAY. AREAS OF FOG CONTINUE TO DEVELOP WITH VISIBILITIES DROPPING UNDER 1SM IN A FEW LOCATIONS. NOT EXPECTING WIDESPREAD DENSE FOG THIS MORNING BUT WILL NEED TO MONITOR OBS OVER THE NEXT FEW HOURS. THE FOG WILL LIFT THIS MORNING BUT WITH LITTLE CHANGE TO THE AIRMASS FOG WILL BE POSSIBLE AGAIN TONIGHT INTO SUNDAY MORNING. A FEW SHOWERS DEVELOPED ACROSS NORTHERN LAKE COUNTY IN NORTHEAST IL LATE FRIDAY EVENING AND PERSISTED FOR A FEW HOURS BEFORE DISSIPATING. OTHERWISE...CONVECTION HAS BEEN FOCUSED FURTHER WEST EARLY THIS MORNING IN THE VICINITY OF THE LOW LEVEL JET. SOME OF THIS ACTIVITY OVER EASTERN IA MAY ARRIVE ACROSS THE WESTERN CWA LATER THIS MORNING...LIKELY IN A DECAYING FORM. BUT OTHER THAN AN ISOLATED SHOWER...EXPECT THE NEXT SEVERAL HOURS TO BE MAINLY DRY. CONFIDENCE REGARDING THUNDERSTORM CHANCES THIS AFTERNOON INTO THIS EVENING IS LOW THOUGH THERE IS SOME CONSENSUS FOR DEVELOPMENT BY EARLY AFTERNOON ACROSS WESTERN/NORTHWEST IL FROM REMNANTS OF CONVECTION OVER EASTERN NEBRASKA/WESTERN IA. HOW FAR IT CONTINUES EAST OR NORTHEAST BEFORE WEAKENING IS ANOTHER UNCERTAINTY. MADE NO SIGNIFICANT CHANGES FOR TODAY MAINTAINING 30-40 POPS. TRENDS WILL NEED TO BE MONITORED THRU THE MORNING. DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES APPROACHING 2 INCHES WILL LEAD TO VERY HEAVY RAIN WITH ANY THUNDERSTORMS THAT DO DEVELOP AND POSSIBLY FLASH FLOODING...ESPECIALLY IF THE RAIN FALLS OVER HARDER HIT AREAS FROM FRIDAY MORNING. THE UPPER RIDGE THEN BUILDS ACROSS THE AREA TONIGHT AND SUNDAY AND PRECIP CHANCES LOOK BELOW MENTIONABLE FROM LATE TONIGHT THROUGH MONDAY MORNING. CAN/T COMPLETELY RULE OUT SOME ISOLATED ACTIVITY... IN PARTICULAR ON A LAKE BREEZE SUNDAY AFTERNOON. A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY WITH SOME DIFFERENCES AS TO HOW FAR SOUTH THIS BOUNDARY WILL SETTLE MONDAY AFTERNOON INTO MONDAY NIGHT. THIS WOULD LIKELY BE THE NEXT CHANCE OF THUNDERSTORMS WITH THE GEM/ECMWF BOTH PUSHING THE FRONT THROUGH MUCH OF THE CWA BY TUESDAY MORNING. THIS BOUNDARY THEN MEANDERS NEAR THE IL/WI BORDER INTO THURSDAY WITH THE POSSIBILITY OF A PROLONGED UNSETTLED PATTERN ACROSS THE AREA. CLOUD COVER/CONVECTION TODAY WILL LIKELY KEEP TEMPS IN THE 80S... THOUGH WITH THE URBAN AREAS STARTING FROM LOWER/MID 70S...ANY LONGER PERIOD OF SUNSHINE TODAY COULD ALLOW A FEW PLACES TO TAG 90. TEMPS WILL WARM A FEW DEGREES SUNDAY BUT SOUTHEASTERLY WINDS WILL KEEP THE LAKESHORE COOLER. MONDAY LOOKS TO BE THE BEST CHANCE FOR TEMPS INTO THE LOWER 90S CWA WIDE BUT WILL BE DEPENDENT ON CLOUD COVER AND TIMING/ARRIVAL OF ANY PRECIP. DEWPOINTS MAY LOWER A FEW DEGREES...BACK INTO THE MID/UPPER 60S ACROSS PARTS OF THE AREA SUNDAY. HEAT INDICES COULD RANGE FROM LOWER/MID 90S TO 100-105 FAR SOUTHWEST. DEWPOINTS THEN BACK INTO THE 70S EVERYWHERE MONDAY WITH HEAT INDICES CLOSER TO 100-105 MOST AREAS WITH STILL THE POTENTIAL TO REACH HEAT ADVISORY CRITERIA ACROSS THE FAR SOUTHERN CWA MONDAY AFTERNOON. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * RAIN WITH A PERIOD OF THUNDER AND POSSIBLE IFR VISIBILITY BETWEEN 19Z-21Z...WITH THE POTENTIAL FOR LINGERING SCATTERED SHRA/TSRA INTO THE EVE. * EAST-NORTHEAST WINDS SHIFTING SOUTHWEST WITH SHOWERS AND STORMS THEN LIKELY BECOMING SOUTHEAST OR EAST AFTERWARD /NEAR 20Z/ AND POTENTIALLY BEING AROUND 10 KT. * POTENTIAL FOR IFR CIGS AND/OR VISIBILITY TONIGHT INTO SUNDAY MORNING. * LAKE BREEZE TURNING WINDS EASTERLY AROUND OR POSSIBLY ABOVE 10 KT SUNDAY. //DISCUSSION...UPDATED 18Z... AREA OF SHOWERS AND STORMS CONTINUES TO MOVE EASTWARD WITH A SLOW WANING TREND...ESPECIALLY IN PART OF THE SEGMENT JUST UPSTREAM OF ORD AND MDW. WHILE THAT IS THE CASE...INCREASED CONVERGENCE BETWEEN THE OUTFLOW AND THE LAKE BREEZE IN UNCAPPED AIR WILL LIKELY SPARK MORE STORMS. THIS ALSO COULD EXTEND THE TSRA TIMING. SO FEEL COMFORTABLE WITH THE TSRA STILL INDICATED IN THE CHICAGOLAND TAFS. STRATIFORM RAIN BEHIND THIS WILL LIKELY BE ACCOMPANIED WITH MVFR CONDITIONS. SCATTERED SHOWERS AND STORMS ARE POSSIBLE BEHIND THIS DURING THE LATTER HALF OF THE AFTERNOON INTO THE EVENING IN THE CONTINUED MOISTURE RICH AIR MASS. THE WIND DIRECTION WILL LIKELY TURN SOUTHWEST AS THE STORMS PASS...AS ALL OBSERVATIONS SITES HAVE INDICATED THAT UPSTREAM AND RADAR SHOW WELL-DEFINED OUTFLOW. THE SPEED OF THE OUTFLOW HAS SLOWED SOME...SO THE DEGREE OF GUSTS AT CHICAGOLAND TAF SITES IS EXPECTED TO BE LESS THAN 30 KT. THE WIND DIRECTION BEHIND THE INITIAL PUSH OF STORMS MAY BECOME VARIABLE...BUT IS ANTICIPATED TO TURN EAST OR SOUTHEAST BASED ON THE SYNOPTIC FLOW AND CLIMATOLOGY FOR POST-THUNDERSTORM WINDS AT ORD. THE MOISTURE IN THE LOW-LEVELS AIDED BY RAIN EARLY THIS AFTERNOON WILL SET THE STAGE ONCE AGAIN FOR FOG AND LOW CIGS TONIGHT...HOWEVER THE COVERAGE OF THIS IS DIFFICULT TO DETERMINE AT THIS TIME. A LAKE BREEZE LOOKS LIKELY ON SUNDAY AFTERNOON INTO NORTHEAST ILLINOIS THAT WILL PROBABLY REACH BOTH ORD AND MDW. //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH IN THUNDER OCCURRING. MEDIUM IN DURATION. LOW IN SHRA/TSRA CHANCES THIS EVE. * LOW IN WIND DIRECTION BETWEEN 19Z AND 21Z...MEDIUM IN WIND CONDITIONS OTHERWISE...INCLUDING LAKE BREEZE TIMING ON SUNDAY. * MEDIUM IN SOME FORM OF IFR RESTRICTION LATE TONIGHT INTO EARLY SUNDAY MORNING. LOW ON WHETHER FOG AND/OR CIG. //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MTF && .MARINE... 340 AM CDT BROAD LOW PRESSURE REMAINS ACROSS THE MID MISSISSIPPI RIVER VALLEY THIS MORNING WHILE STRONGER LOW PRESSURE ORGANIZES OVER THE CENTRAL HIGH PLAINS. AN UPPER LOW SPINNING OVER THE NORTHWEST U.S. WILL HELP KICK THE HIGH PLAINS LOW NORTHWARD INTO SUNDAY WHILE HIGH PRESSURE MOVES FROM QUEBEC TO NEW ENGLAND AND THE MID-ATLANTIC STATES. EAST TO NORTHEAST WINDS WILL CONTINUE ACROSS LAKE MICHIGAN TODAY BUT WILL SHIFT TO THE SOUTHEAST INTO SUNDAY...WITH SPEEDS INCREASING MODESTLY. THE MAIN TRACK OF LOW PRESSURE WILL REMAIN OFF TO THE NORTHWEST OF THE LAKE INTO THE MIDDLE OF NEXT WEEK WHICH WILL KEEP A SOUTHERLY WIND GOING...THOUGH SOUTHERN AREAS MAY SEE WINDS SHIFT ONSHORE EACH AFTERNOON WHERE THE PRESSURE GRADIENT IS WEAKER. A FRONTAL BOUNDARY IS EXPECTED TO DROP OVER NORTHERN PARTS OF THE LAKE TOWARD MIDWEEK WHICH WOULD LEAD TO EAST OR NORTHEAST WINDS ACROSS THE NORTH WITH SOUTHERLY WINDS CONTINUING SOUTH. MEDIUM RANGE GUIDANCE CONFLICTS WITH HOW QUICKLY THIS FRONT MOVES ACROSS THE LAKE AND THE STRENGTH OF COLD AIR BEHIND IT DURING THE MIDDLE OF NEXT WEEK LEADING TO LOW FORECAST CONFIDENCE BY THAT TIME. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...DENSE FOG ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
109 PM CDT SAT AUG 23 2014 .DISCUSSION... 959 AM CDT THE FORECAST HAS BEEN UPDATED TO REFLECT GREATER CLOUD COVER AREAWIDE AND HIGHER POPS ACROSS MAINLY NORTH CENTRAL ILLINOIS DURING THE EARLY-MID AFTERNOON. A BROAD MESOSCALE CONVECTIVE SYSTEM WITH A LINE OF STORMS ON ITS FRONT EDGE IS CURRENTLY ADVANCING EAST OVER THE MISSISSIPPI RIVER AND FAR WESTERN ILLINOIS. THIS CONTINUES TO HOLD TOGETHER WELL WITH ONLY SUBTLE CLOUD TOP WARMING AND NO FADE IN LIGHTNING ACTIVITY OVER THE PAST COUPLE HOURS. THIS COMPLEX HAS BEEN ONGOING FOR OVER NINE HOURS SO NOT SURPRISED TO SEE THAT THE RADAR LOOP INDICATES THE LIKELY PRESENCE OF A CONVECTIVELY-INDUCED VORTICITY MAXIMUM /MCV/ IN FAR EASTERN IA. THIS WITH A COLD POOL IS HELPING TO USHER PUSH THE STORMS MORE EASTWARD THAN THE NORTHEAST MOVEMENT OF THE PARENT SHORTWAVE WOULD INDICATE. DESPITE WHAT SHOULD BE A GRADUAL FACE INTO THE EARLY AFTERNOON WITH THE UPPER SUPPORT MOVING NORTHEAST AND A DECAYING LOW-LEVEL JET PER PROFILERS...2.2 INCH PWAT AIR /99TH PERCENTILE/ AHEAD OF THE MCV WILL LIKELY SUPPORT SHOWERS AND SOME STORMS INTO NORTH CENTRAL ILLINOIS BETWEEN NOON AND 3 PM. STILL SEEING SOME EMBEDDED HOURLY PRECIP REPORTS OF A HALF TO ONE INCH WITH THIS...AND SOME OF THIS EFFICIENCY COULD CERTAINLY OCCUR ALONG AND WEST OF I-39 DURING THE EARLY AFTERNOON. UNDER THE INFLUENCE OF WEAK UPPER LEVEL FLOW...THE MCV IS FORECAST BY THE RAP AND NAM TO CONTINUE TO SLOW AS IT MOVES INTO NORTH CENTRAL IL. DESTABILIZATION AHEAD OF IT MAY SUPPORT ISOLATED OR SCATTERED SHOWERS/STORMS LATER THIS AFTERNOON FURTHER EAST TOWARD CHICAGO AND THE I-57 CORRIDOR INTO NORTHWEST INDIANA...BUT CONFIDENCE ON THIS IS LOW AS ANVIL SHIELD WILL INHIBIT THE RATE OF WARMTH...WITH MOST GUIDANCE INDICATING THE PRESENCE OF A CAP AND LOW-LEVEL FLOW OFF THE LAKE IN FAR NORTHEAST IL. MINOR TWEAKS MADE TO HOURLY TEMPERATURES AND DEW POINTS. MTF //PREV DISCUSSION... 327 AM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES/TIMING THROUGH THE PERIOD ALONG WITH HIGH TEMPERATURES/HEAT INDICES THROUGH MONDAY. AREAS OF FOG CONTINUE TO DEVELOP WITH VISIBILITIES DROPPING UNDER 1SM IN A FEW LOCATIONS. NOT EXPECTING WIDESPREAD DENSE FOG THIS MORNING BUT WILL NEED TO MONITOR OBS OVER THE NEXT FEW HOURS. THE FOG WILL LIFT THIS MORNING BUT WITH LITTLE CHANGE TO THE AIRMASS FOG WILL BE POSSIBLE AGAIN TONIGHT INTO SUNDAY MORNING. A FEW SHOWERS DEVELOPED ACROSS NORTHERN LAKE COUNTY IN NORTHEAST IL LATE FRIDAY EVENING AND PERSISTED FOR A FEW HOURS BEFORE DISSIPATING. OTHERWISE...CONVECTION HAS BEEN FOCUSED FURTHER WEST EARLY THIS MORNING IN THE VICINITY OF THE LOW LEVEL JET. SOME OF THIS ACTIVITY OVER EASTERN IA MAY ARRIVE ACROSS THE WESTERN CWA LATER THIS MORNING...LIKELY IN A DECAYING FORM. BUT OTHER THAN AN ISOLATED SHOWER...EXPECT THE NEXT SEVERAL HOURS TO BE MAINLY DRY. CONFIDENCE REGARDING THUNDERSTORM CHANCES THIS AFTERNOON INTO THIS EVENING IS LOW THOUGH THERE IS SOME CONSENSUS FOR DEVELOPMENT BY EARLY AFTERNOON ACROSS WESTERN/NORTHWEST IL FROM REMNANTS OF CONVECTION OVER EASTERN NEBRASKA/WESTERN IA. HOW FAR IT CONTINUES EAST OR NORTHEAST BEFORE WEAKENING IS ANOTHER UNCERTAINTY. MADE NO SIGNIFICANT CHANGES FOR TODAY MAINTAINING 30-40 POPS. TRENDS WILL NEED TO BE MONITORED THRU THE MORNING. DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES APPROACHING 2 INCHES WILL LEAD TO VERY HEAVY RAIN WITH ANY THUNDERSTORMS THAT DO DEVELOP AND POSSIBLY FLASH FLOODING...ESPECIALLY IF THE RAIN FALLS OVER HARDER HIT AREAS FROM FRIDAY MORNING. THE UPPER RIDGE THEN BUILDS ACROSS THE AREA TONIGHT AND SUNDAY AND PRECIP CHANCES LOOK BELOW MENTIONABLE FROM LATE TONIGHT THROUGH MONDAY MORNING. CAN/T COMPLETELY RULE OUT SOME ISOLATED ACTIVITY... IN PARTICULAR ON A LAKE BREEZE SUNDAY AFTERNOON. A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY WITH SOME DIFFERENCES AS TO HOW FAR SOUTH THIS BOUNDARY WILL SETTLE MONDAY AFTERNOON INTO MONDAY NIGHT. THIS WOULD LIKELY BE THE NEXT CHANCE OF THUNDERSTORMS WITH THE GEM/ECMWF BOTH PUSHING THE FRONT THROUGH MUCH OF THE CWA BY TUESDAY MORNING. THIS BOUNDARY THEN MEANDERS NEAR THE IL/WI BORDER INTO THURSDAY WITH THE POSSIBILITY OF A PROLONGED UNSETTLED PATTERN ACROSS THE AREA. CLOUD COVER/CONVECTION TODAY WILL LIKELY KEEP TEMPS IN THE 80S... THOUGH WITH THE URBAN AREAS STARTING FROM LOWER/MID 70S...ANY LONGER PERIOD OF SUNSHINE TODAY COULD ALLOW A FEW PLACES TO TAG 90. TEMPS WILL WARM A FEW DEGREES SUNDAY BUT SOUTHEASTERLY WINDS WILL KEEP THE LAKESHORE COOLER. MONDAY LOOKS TO BE THE BEST CHANCE FOR TEMPS INTO THE LOWER 90S CWA WIDE BUT WILL BE DEPENDENT ON CLOUD COVER AND TIMING/ARRIVAL OF ANY PRECIP. DEWPOINTS MAY LOWER A FEW DEGREES...BACK INTO THE MID/UPPER 60S ACROSS PARTS OF THE AREA SUNDAY. HEAT INDICES COULD RANGE FROM LOWER/MID 90S TO 100-105 FAR SOUTHWEST. DEWPOINTS THEN BACK INTO THE 70S EVERYWHERE MONDAY WITH HEAT INDICES CLOSER TO 100-105 MOST AREAS WITH STILL THE POTENTIAL TO REACH HEAT ADVISORY CRITERIA ACROSS THE FAR SOUTHERN CWA MONDAY AFTERNOON. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * RAIN WITH A PERIOD OF THUNDER AND POSSIBLE IFR VISIBILITY BETWEEN 19Z-21Z...WITH THE POTENTIAL FOR LINGERING SCATTERED SHRA/TSRA INTO THE EVE. * EAST-NORTHEAST WINDS SHIFTING SOUTHWEST WITH SHOWERS AND STORMS THEN LIKELY BECOMING SOUTHEAST OR EAST AFTERWARD /NEAR 20Z/ AND POTENTIALLY BEING AROUND 10 KT. * POTENTIAL FOR IFR CIGS AND/OR VISIBILITY TONIGHT INTO SUNDAY MORNING. * LAKE BREEZE TURNING WINDS EASTERLY AROUND OR POSSIBLY ABOVE 10 KT SUNDAY. //DISCUSSION...UPDATED 18Z... AREA OF SHOWERS AND STORMS CONTINUES TO MOVE EASTWARD WITH A SLOW WANING TREND...ESPECIALLY IN PART OF THE SEGMENT JUST UPSTREAM OF ORD AND MDW. WHILE THAT IS THE CASE...INCREASED CONVERGENCE BETWEEN THE OUTFLOW AND THE LAKE BREEZE IN UNCAPPED AIR WILL LIKELY SPARK MORE STORMS. THIS ALSO COULD EXTEND THE TSRA TIMING. SO FEEL COMFORTABLE WITH THE TSRA STILL INDICATED IN THE CHICAGOLAND TAFS. STRATIFORM RAIN BEHIND THIS WILL LIKELY BE ACCOMPANIED WITH MVFR CONDITIONS. SCATTERED SHOWERS AND STORMS ARE POSSIBLE BEHIND THIS DURING THE LATTER HALF OF THE AFTERNOON INTO THE EVENING IN THE CONTINUED MOISTURE RICH AIR MASS. THE WIND DIRECTION WILL LIKELY TURN SOUTHWEST AS THE STORMS PASS...AS ALL OBSERVATIONS SITES HAVE INDICATED THAT UPSTREAM AND RADAR SHOW WELL-DEFINED OUTFLOW. THE SPEED OF THE OUTFLOW HAS SLOWED SOME...SO THE DEGREE OF GUSTS AT CHICAGOLAND TAF SITES IS EXPECTED TO BE LESS THAN 30 KT. THE WIND DIRECTION BEHIND THE INITIAL PUSH OF STORMS MAY BECOME VARIABLE...BUT IS ANTICIPATED TO TURN EAST OR SOUTHEAST BASED ON THE SYNOPTIC FLOW AND CLIMATOLOGY FOR POST-THUNDERSTORM WINDS AT ORD. THE MOISTURE IN THE LOW-LEVELS AIDED BY RAIN EARLY THIS AFTERNOON WILL SET THE STAGE ONCE AGAIN FOR FOG AND LOW CIGS TONIGHT...HOWEVER THE COVERAGE OF THIS IS DIFFICULT TO DETERMINE AT THIS TIME. A LAKE BREEZE LOOKS LIKELY ON SUNDAY AFTERNOON INTO NORTHEAST ILLINOIS THAT WILL PROBABLY REACH BOTH ORD AND MDW. //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH IN THUNDER OCCURRING. MEDIUM IN DURATION. LOW IN SHRA/TSRA CHANCES THIS EVE. * LOW IN WIND DIRECTION BETWEEN 19Z AND 21Z...MEDIUM IN WIND CONDITIONS OTHERWISE...INCLUDING LAKE BREEZE TIMING ON SUNDAY. * MEDIUM IN SOME FORM OF IFR RESTRICTION LATE TONIGHT INTO EARLY SUNDAY MORNING. LOW ON WHETHER FOG AND/OR CIG. //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MTF && .MARINE... 340 AM CDT BROAD LOW PRESSURE REMAINS ACROSS THE MID MISSISSIPPI RIVER VALLEY THIS MORNING WHILE STRONGER LOW PRESSURE ORGANIZES OVER THE CENTRAL HIGH PLAINS. AN UPPER LOW SPINNING OVER THE NORTHWEST U.S. WILL HELP KICK THE HIGH PLAINS LOW NORTHWARD INTO SUNDAY WHILE HIGH PRESSURE MOVES FROM QUEBEC TO NEW ENGLAND AND THE MID-ATLANTIC STATES. EAST TO NORTHEAST WINDS WILL CONTINUE ACROSS LAKE MICHIGAN TODAY BUT WILL SHIFT TO THE SOUTHEAST INTO SUNDAY...WITH SPEEDS INCREASING MODESTLY. THE MAIN TRACK OF LOW PRESSURE WILL REMAIN OFF TO THE NORTHWEST OF THE LAKE INTO THE MIDDLE OF NEXT WEEK WHICH WILL KEEP A SOUTHERLY WIND GOING...THOUGH SOUTHERN AREAS MAY SEE WINDS SHIFT ONSHORE EACH AFTERNOON WHERE THE PRESSURE GRADIENT IS WEAKER. A FRONTAL BOUNDARY IS EXPECTED TO DROP OVER NORTHERN PARTS OF THE LAKE TOWARD MIDWEEK WHICH WOULD LEAD TO EAST OR NORTHEAST WINDS ACROSS THE NORTH WITH SOUTHERLY WINDS CONTINUING SOUTH. MEDIUM RANGE GUIDANCE CONFLICTS WITH HOW QUICKLY THIS FRONT MOVES ACROSS THE LAKE AND THE STRENGTH OF COLD AIR BEHIND IT DURING THE MIDDLE OF NEXT WEEK LEADING TO LOW FORECAST CONFIDENCE BY THAT TIME. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...DENSE FOG ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1123 AM CDT SAT AUG 23 2014 .DISCUSSION... 959 AM CDT THE FORECAST HAS BEEN UPDATED TO REFLECT GREATER CLOUD COVER AREAWIDE AND HIGHER POPS ACROSS MAINLY NORTH CENTRAL ILLINOIS DURING THE EARLY-MID AFTERNOON. A BROAD MESOSCALE CONVECTIVE SYSTEM WITH A LINE OF STORMS ON ITS FRONT EDGE IS CURRENTLY ADVANCING EAST OVER THE MISSISSIPPI RIVER AND FAR WESTERN ILLINOIS. THIS CONTINUES TO HOLD TOGETHER WELL WITH ONLY SUBTLE CLOUD TOP WARMING AND NO FADE IN LIGHTNING ACTIVITY OVER THE PAST COUPLE HOURS. THIS COMPLEX HAS BEEN ONGOING FOR OVER NINE HOURS SO NOT SURPRISED TO SEE THAT THE RADAR LOOP INDICATES THE LIKELY PRESENCE OF A CONVECTIVELY-INDUCED VORTICITY MAXIMUM /MCV/ IN FAR EASTERN IA. THIS WITH A COLD POOL IS HELPING TO USHER PUSH THE STORMS MORE EASTWARD THAN THE NORTHEAST MOVEMENT OF THE PARENT SHORTWAVE WOULD INDICATE. DESPITE WHAT SHOULD BE A GRADUAL FACE INTO THE EARLY AFTERNOON WITH THE UPPER SUPPORT MOVING NORTHEAST AND A DECAYING LOW-LEVEL JET PER PROFILERS...2.2 INCH PWAT AIR /99TH PERCENTILE/ AHEAD OF THE MCV WILL LIKELY SUPPORT SHOWERS AND SOME STORMS INTO NORTH CENTRAL ILLINOIS BETWEEN NOON AND 3 PM. STILL SEEING SOME EMBEDDED HOURLY PRECIP REPORTS OF A HALF TO ONE INCH WITH THIS...AND SOME OF THIS EFFICIENCY COULD CERTAINLY OCCUR ALONG AND WEST OF I-39 DURING THE EARLY AFTERNOON. UNDER THE INFLUENCE OF WEAK UPPER LEVEL FLOW...THE MCV IS FORECAST BY THE RAP AND NAM TO CONTINUE TO SLOW AS IT MOVES INTO NORTH CENTRAL IL. DESTABILIZATION AHEAD OF IT MAY SUPPORT ISOLATED OR SCATTERED SHOWERS/STORMS LATER THIS AFTERNOON FURTHER EAST TOWARD CHICAGO AND THE I-57 CORRIDOR INTO NORTHWEST INDIANA...BUT CONFIDENCE ON THIS IS LOW AS ANVIL SHIELD WILL INHIBIT THE RATE OF WARMTH...WITH MOST GUIDANCE INDICATING THE PRESENCE OF A CAP AND LOW-LEVEL FLOW OFF THE LAKE IN FAR NORTHEAST IL. MINOR TWEAKS MADE TO HOURLY TEMPERATURES AND DEW POINTS. MTF //PREV DISCUSSION... 327 AM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES/TIMING THROUGH THE PERIOD ALONG WITH HIGH TEMPERATURES/HEAT INDICES THROUGH MONDAY. AREAS OF FOG CONTINUE TO DEVELOP WITH VISIBILITIES DROPPING UNDER 1SM IN A FEW LOCATIONS. NOT EXPECTING WIDESPREAD DENSE FOG THIS MORNING BUT WILL NEED TO MONITOR OBS OVER THE NEXT FEW HOURS. THE FOG WILL LIFT THIS MORNING BUT WITH LITTLE CHANGE TO THE AIRMASS FOG WILL BE POSSIBLE AGAIN TONIGHT INTO SUNDAY MORNING. A FEW SHOWERS DEVELOPED ACROSS NORTHERN LAKE COUNTY IN NORTHEAST IL LATE FRIDAY EVENING AND PERSISTED FOR A FEW HOURS BEFORE DISSIPATING. OTHERWISE...CONVECTION HAS BEEN FOCUSED FURTHER WEST EARLY THIS MORNING IN THE VICINITY OF THE LOW LEVEL JET. SOME OF THIS ACTIVITY OVER EASTERN IA MAY ARRIVE ACROSS THE WESTERN CWA LATER THIS MORNING...LIKELY IN A DECAYING FORM. BUT OTHER THAN AN ISOLATED SHOWER...EXPECT THE NEXT SEVERAL HOURS TO BE MAINLY DRY. CONFIDENCE REGARDING THUNDERSTORM CHANCES THIS AFTERNOON INTO THIS EVENING IS LOW THOUGH THERE IS SOME CONSENSUS FOR DEVELOPMENT BY EARLY AFTERNOON ACROSS WESTERN/NORTHWEST IL FROM REMNANTS OF CONVECTION OVER EASTERN NEBRASKA/WESTERN IA. HOW FAR IT CONTINUES EAST OR NORTHEAST BEFORE WEAKENING IS ANOTHER UNCERTAINTY. MADE NO SIGNIFICANT CHANGES FOR TODAY MAINTAINING 30-40 POPS. TRENDS WILL NEED TO BE MONITORED THRU THE MORNING. DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES APPROACHING 2 INCHES WILL LEAD TO VERY HEAVY RAIN WITH ANY THUNDERSTORMS THAT DO DEVELOP AND POSSIBLY FLASH FLOODING...ESPECIALLY IF THE RAIN FALLS OVER HARDER HIT AREAS FROM FRIDAY MORNING. THE UPPER RIDGE THEN BUILDS ACROSS THE AREA TONIGHT AND SUNDAY AND PRECIP CHANCES LOOK BELOW MENTIONABLE FROM LATE TONIGHT THROUGH MONDAY MORNING. CAN/T COMPLETELY RULE OUT SOME ISOLATED ACTIVITY... IN PARTICULAR ON A LAKE BREEZE SUNDAY AFTERNOON. A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY WITH SOME DIFFERENCES AS TO HOW FAR SOUTH THIS BOUNDARY WILL SETTLE MONDAY AFTERNOON INTO MONDAY NIGHT. THIS WOULD LIKELY BE THE NEXT CHANCE OF THUNDERSTORMS WITH THE GEM/ECMWF BOTH PUSHING THE FRONT THROUGH MUCH OF THE CWA BY TUESDAY MORNING. THIS BOUNDARY THEN MEANDERS NEAR THE IL/WI BORDER INTO THURSDAY WITH THE POSSIBILITY OF A PROLONGED UNSETTLED PATTERN ACROSS THE AREA. CLOUD COVER/CONVECTION TODAY WILL LIKELY KEEP TEMPS IN THE 80S... THOUGH WITH THE URBAN AREAS STARTING FROM LOWER/MID 70S...ANY LONGER PERIOD OF SUNSHINE TODAY COULD ALLOW A FEW PLACES TO TAG 90. TEMPS WILL WARM A FEW DEGREES SUNDAY BUT SOUTHEASTERLY WINDS WILL KEEP THE LAKESHORE COOLER. MONDAY LOOKS TO BE THE BEST CHANCE FOR TEMPS INTO THE LOWER 90S CWA WIDE BUT WILL BE DEPENDENT ON CLOUD COVER AND TIMING/ARRIVAL OF ANY PRECIP. DEWPOINTS MAY LOWER A FEW DEGREES...BACK INTO THE MID/UPPER 60S ACROSS PARTS OF THE AREA SUNDAY. HEAT INDICES COULD RANGE FROM LOWER/MID 90S TO 100-105 FAR SOUTHWEST. DEWPOINTS THEN BACK INTO THE 70S EVERYWHERE MONDAY WITH HEAT INDICES CLOSER TO 100-105 MOST AREAS WITH STILL THE POTENTIAL TO REACH HEAT ADVISORY CRITERIA ACROSS THE FAR SOUTHERN CWA MONDAY AFTERNOON. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * TEMPORARY MVFR CIGS...ABOVE 1500FT...INTO THIS AFTERNOON. * EAST TO NORTHEAST WINDS THROUGH THE DAY WITH SPEEDS POSSIBLY APPROACHING 10 KT...WITH A CHANCE WINDS COULD GET DISRUPTED IN DIRECTION BY SHRA/TSRA. * TEMPORARY SHRA LIKELY WITHIN THE 19Z-22Z WINDOW WITH THE POSSIBILITY OF TSRA. * CHANCE FOR REDUCED CIGS/VSBY OVERNIGHT. MTF/MDB //DISCUSSION...UPDATED 16Z... AREA OF SHOWERS AND STORMS CONTINUE TO DRIVE ITSELF EASTWARD INTO NORTH CENTRAL IL AS OF 16Z. THIS SHOULD CONTINUE TO MOVE EAST...WITH AN EXPECTATION OF SOME DISSIPATION IN COVERAGE. THAT SAID...INTENSITY MAY ACTUALLY START TO INCREASE FURTHER EAST AS THE AREA MOVES INTO MORE UNSTABLE AIR. SO MAY NEED TO ADD TSRA MENTION TO CHICAGOLAND TAF SITES. MTF PREV DISCUSSION...UPDATED 12Z... WEAK LOW LEVEL FLOW FROM LAKE MICHIGAN COMBINED WITH THE VERY MOIST AIRMASS HAS ALLOWED STRATUS/FOG TO SLOWLY PUSH INLAND THIS MORNING. WITH ABUNDANT CIRRUS OVERHEAD WITH MORE UPSTREAM FROM CONVECTION ACROSS IOWA IMPROVEMENT MAY BE VERY SLOW THIS MORNING SO ADJUSTMENTS MAY BE NEEDED OVER THE NEXT FEW HOURS. WITH GYY/MDW/RFD BEING ON THE FRINGES OF THE IFR IMPROVEMENT MAY BE STEADIER THERE WITH ORD/DPA LIKELY BEING THE SLOWEST. DO EXPECT THAT VFR WILL RETURN HOWEVER. EASTERLY WINDS WILL BE IN PLACE THROUGH THE DAY WITH SPEEDS EXPECTED TO BE UNDER 10 KT. SPOTTY CONVECTION HAS BEEN FESTERING OVER FAR EASTERN IOWA AHEAD OF A MUCH LARGER COMPLEX ACROSS CENTRAL IOWA. THIS ACTIVITY IS MOVING NORTHEASTWARD BUT STEERING FLOW WOULD TAKE IT MORE EASTERLY THOUGH AT LEAST SOME DECAY IS POSSIBLE IN THE NEAR TERM. HAVE LOW CONFIDENCE IN HOW CONVECTION PLAYS OUT THE REST OF THE DAY BUT AT LEAST SCATTERED TSRA IS POSSIBLE AS THE PARENT FORCING DRIFTS TOWARD THE AREA LATER TODAY. THIS POINTS TO THE AFTERNOON/EVENING BEING THE MOST LIKELY PERIOD FOR STORMS BUT THE BEST CHANCES MAY BE FOCUSED WEST OF THE TERMINALS. GIVEN THE UNCERTAINTY WILL KEEP THE TAFS DRY FOR NOW BUT EXPECT THAT RFD MAY NEED A MENTION OF TSRA ADDED BEFORE TOO LONG. WITH CONTINUED WEAK FLOW AND HIGH HUMIDITY MORE FOG AND STRATUS WILL BE POSSIBLE TONIGHT. MDB //ORD AND MDW CONFIDENCE...UPDATED 16Z... * MEDIUM-HIGH IN OCCASIONAL MVFR CIGS. * MEDIUM IN WIND DIRECTION AND SPEED. * MEDIUM IN SHRA AND LOW IN TSRA OCCURRING AT THE AIRFIELDS. * MEDIUM THAT THERE WILL BE SOME SORT OF CIG/VSBY REDUCTION TONIGHT. MTF/MDB //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MDB && .MARINE... 340 AM CDT BROAD LOW PRESSURE REMAINS ACROSS THE MID MISSISSIPPI RIVER VALLEY THIS MORNING WHILE STRONGER LOW PRESSURE ORGANIZES OVER THE CENTRAL HIGH PLAINS. AN UPPER LOW SPINNING OVER THE NORTHWEST U.S. WILL HELP KICK THE HIGH PLAINS LOW NORTHWARD INTO SUNDAY WHILE HIGH PRESSURE MOVES FROM QUEBEC TO NEW ENGLAND AND THE MID-ATLANTIC STATES. EAST TO NORTHEAST WINDS WILL CONTINUE ACROSS LAKE MICHIGAN TODAY BUT WILL SHIFT TO THE SOUTHEAST INTO SUNDAY...WITH SPEEDS INCREASING MODESTLY. THE MAIN TRACK OF LOW PRESSURE WILL REMAIN OFF TO THE NORTHWEST OF THE LAKE INTO THE MIDDLE OF NEXT WEEK WHICH WILL KEEP A SOUTHERLY WIND GOING...THOUGH SOUTHERN AREAS MAY SEE WINDS SHIFT ONSHORE EACH AFTERNOON WHERE THE PRESSURE GRADIENT IS WEAKER. A FRONTAL BOUNDARY IS EXPECTED TO DROP OVER NORTHERN PARTS OF THE LAKE TOWARD MIDWEEK WHICH WOULD LEAD TO EAST OR NORTHEAST WINDS ACROSS THE NORTH WITH SOUTHERLY WINDS CONTINUING SOUTH. MEDIUM RANGE GUIDANCE CONFLICTS WITH HOW QUICKLY THIS FRONT MOVES ACROSS THE LAKE AND THE STRENGTH OF COLD AIR BEHIND IT DURING THE MIDDLE OF NEXT WEEK LEADING TO LOW FORECAST CONFIDENCE BY THAT TIME. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...DENSE FOG ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
216 PM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 401 AM EDT SAT AUG 23 2014 WARM AND HUMID CONDITIONS WILL PERSIST FOR ONE MORE DAY BEFORE A BRIEF BREAK IN THE STICKY CONDITIONS ARRIVES TONIGHT INTO SUNDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND EVENING WITH CHANCES DIMINISHING TONIGHT. DRY CONDITIONS ARE EXPECTED UNTIL TUESDAY WHEN A COLD FRONT BEGINS TO APPROACH THE AREA. HIGHS WILL BE IN THE 80S WITH LOWS IN THE 60S THE NEXT COUPLE OF DAYS. && .UPDATE... ISSUED AT 1116 AM EDT SAT AUG 23 2014 FOG HAS DISSIPATED ACROSS MOST OF THE AREA THIS MORNING...WITH THE EXCEPTION BEING JUST SOME PATCHY 2-5 MILE VISIBILITIES WHERE STRATUS DECK HAS PERSISTED THE LONGEST FROM SOUTHWEST LOWER MICHIGAN SOUTHEASTWARD TO LIMA OHIO. MCS ACROSS EASTERN IOWA/NORTHWEST ILLINOIS WILL BE THE NEXT ITEM OF CONCERN TO ADDRESS FOR THE LOCAL AREA. CORFIDI VECTORS SUPPORT MORE OF AN EAST/SOUTH PROPAGATION THIS AFTERNOON...WITH ORIENTATION OF STRONGEST INSTABILITY AXIS ALSO FAVORING GENERAL PROPAGATION/DEVELOPMENT TO THE SOUTHEAST...CLIPPING ESPECIALLY SOUTHWEST PORTIONS OF THE AREA. HAVE INCREASED TO MID RANGE CHANCE POPS ACROSS THE FAR SOUTHWEST TO ACCOUNT FOR THIS...WHILE MAINTAINING OVERALL SOUTHWEST TO NORTHEAST POP GRADIENT FROM PREVIOUS FORECAST. SEVERE WEATHER POTENTIAL STILL APPEARS TO BE QUITE LOW WITH ANY LOW END/ISOLD RISK LIKELY BEING CONFINED TO RICHER LOW LEVEL MOISTURE AXIS ACROSS SOUTHWEST PORTIONS OF THE AREA. WHILE INSTABILITY WILL BE MAXIMIZED ACROSS THE SOUTHWEST...THIS MAY REPRESENT A MINIMUM IN DEEP LAYER SHEAR. ONLY CAVEAT TO THIS WOULD BE FOR SMALLER SCALE AREA OF LOCALLY ENHANCED SHEAR ASSOCIATED WITH CONVECTIVELY ENHANCED VORT MAX EMANATING FROM IOWA/ILLINOIS CONVECTION. GIVEN HEAVY RAINFALL OVER PAST FEW DAYS ACROSS THE SOUTHWEST...WILL ESPECIALLY HAVE TO MONITOR FOR ANY STORMS CAPABLE OF LOCALIZED HEAVIER RAINFALL. TEMPS APPEAR TO BE IN GOOD SHAPE WITH JUST SOME MINOR TWEAKS TO MORNING DIURNAL CURVE TO ACCOUNT FOR LINGERING STRATUS DECK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 401 AM EDT SAT AUG 23 2014 SEVERAL SMALLER ITEMS TO TRY TO SORT OUT FOR THE FORECAST. FIRST OFF WILL BE COMBINATION OF MOIST LOW LEVEL AIR MASS AND MOSTLY CLEAR SKIES ALLOWING FOR STRATUS/FOG DEVELOPMENT ACROSS THE AREA. OBSERVATIONS HAVE BEEN SHOWING THIS ALREADY TAKING PLACE...WITH ISSUES EXPECTED TO PERSIST THROUGH AT LEAST 10 AM BEFORE SUFFICIENT MIXING OCCURS TO HELP BREAK THINGS UP. NEXT UP WILL BE ATTEMPT TO ADVECT IN SOMEWHAT DRIER AIR FROM THE NE AGAINST THE PERSISTENT BUT WEAK SW FLOW ACROSS MUCH OF THE WESTERN GREAT LAKES. A SUBTLE BOUNDARY WAS LOCATED FROM S LK MICHIGAN TO VICINITY OF FT WAYNE. THIS FEATURE...COMBINED WITH WHAT APPEARS TO BE A MID LEVEL DISTURBANCE OR SERIES OF GRAVITY WAVES...HELPED SPARK SMALL AREAS OF SLOW MOVING SHOWERS AND STORMS THAT HAVE SINCE DISSIPATED. LOCATIONS ALONG AND SW OF THIS BOUNDARY WILL SEE A CHANCE FOR HIT OR MISS SHOWERS/STORMS THIS AFTERNOON/EVE IF SUFFICIENT HEATING CAN TAKE PLACE. WARM AND HUMID CONDITIONS WILL REMAIN UNTIL THE NE FLOW CAN STRENGTHEN SLIGHTLY AS RIDGE INFLUENCE BRIEFLY RELAXES WITH DEWPOINTS DROPPING INTO THE MID 60S (LOW 60S NE). A FEW RUNS OF THE RUC TRY TO BRING THIS DRIER AIR A BIT FASTER IN NE SECTIONS THAT CURRENTLY DEPICTED. GIVEN WEAK NATURE OF SLOW...THINK SLOWER IS BETTER AT THIS POINT UNTIL DEGREE OF MIXING CAN BE DETERMINED. AS A RESULT...HIGHS SHOULD REACH THE MID 80S WITH HEAT INDICES NEAR OR JUST INTO THE 90S. NE FLOW WILL PUSH AXIS OF BEST PRECIPITATION POTENTIAL TO THE SW OF THE REGION DURING THE EVENING HOURS...LEADING TO WHAT SHOULD BE A PLEASANTLY DRY NIGHT AS LOWS DROP INTO THE MID 60S TO NEAR 70. HAVE KEPT A LINGERING SLGT CHC OF SHOWERS IN FAR SW AREAS EARLY EVENING BUT THEN REMOVED ALL MENTION OF PRECIPITATION AFTER 3Z. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 401 AM EDT SAT AUG 23 2014 STRONG SHRTWV MOVG THROUGH NRN NEVADA THIS MORNING EXPECTED TO LIFT SLOWLY NE THROUGH THE NRN HIGH PLAINS SUNDAY WITH DOWNSTREAM RIDGE MOVG EAST ACROSS OUR CWA. LACK OF FORCING AND A LITTLE DRIER AIR ADVECTING INTO OUR AREA IN THE H925-H85 LAYER DUE TO EASTERLY FLOW AROUND STRENGTHENING ANTICYCLONE OVER THE LWR GRTLKS SUGGESTS DRY CONDITIONS ACROSS OUR AREA. GOOD DEAL OF SUNSHINE SHOULD ALLOW MIXING UP TO NEAR H850 WHICH WOULD RESULT IN HIGHS IN THE M-U80S. NRN PLAINS SHRTWV EXPECTED TO MOVE EAST TO ONTARIO ON MONDAY. RIDGE OVER THE UPR GRTLKS WILL FLATTEN OUT IN RESPONSE BUT SHOULD HOLD STRONG IN OUR AREA KEEPING CONDITIONS DRY. TEMPS EXPECTED TO CONTINUE SLOW WARMING TREND AS WINDS VEER MORE SOUTHERLY WITH HIGHS IN THE U80S/L90S. ONTARIO SHRTWV EXPECTED TO SHEAR OUT AND LIFT ENE INTO QUEBEC TUE WITH TRAILING CDFNT SINKING SLOWLY SOUTH INTO OR CLOSE TO NRN PORTION OF OUR CWA BY WED MORNING. TSTMS SHOULD DEVELOP ALONG THE FRONT AND MAY PROPAGATE SE INTO UNSTABLE AIRMASS OVER OUR AREA... BUT CAPPING INVERSION MAKES THIS SCENARIO DOUBTFUL... SO JUST CONTD WITH LOW CHC POPS. TEMPS SHOULD REMAIN WELL ABOVE NORMAL WITH HIGHS AROUND 90 AND LOWS NEAR 70. MODEL SOLUTIONS DIVERGE SIGNIFICANTLY LATE WEEK WITH ECMWF/GEM SUGGESTING NEXT STRONG SHRTWV TO MOVE INTO MEAN WRN TROF WILL CUT-OFF OVER THE ROCKIES AND THEN MOVE SLOWLY EAST... WHILE GFS SUGGESTS A MORE PROGRESSIVE SCENARIO. IN EITHER CASE... LOW POPS STILL WARRANTED FOR WED-THU... WHILE GFS INDICATES COOLER/DRIER CONDITIONS WILL OVERSPREAD THE AREA BY FRIDAY. THIS SOLUTION IN BETTER AGREEMENT WITH GOING FCST AND GIVEN EXCESSIVE UNCERTAINTY WITH LARGE MODEL DIFFERENCES... STAYED CLOSE TO PREVIOUS FCST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 152 PM EDT SAT AUG 23 2014 CONVECTIVE COMPLEX ACROSS NORTHERN ILLINOIS HAS EXHIBITED SOME TREND TO SOUTHEAST PROPAGATION OVER THE LAST HOUR AND EXPECTING THIS OVERALL TREND TO PERSIST THROUGH THE REMAINDER OF THE AFTERNOON. WILL HAVE TO MONITOR FOR OUTFLOW ACCELERATING AHEAD OF THIS LINE TO POSSIBLY BE FOCUS FOR ADDITIONAL THUNDERSTORM DEVELOPMENT AT KSBN LATE THIS AFTERNOON. IN THE MEANTIME...WILL ALSO NEED TO MONITOR FOR POTENTIAL ISOLATED DEVELOPMENT ALONG WEAK LAKE BREEZE WHICH HAS FORMED...WITH CU BEING MORE VERTICALLY DEVELOPED RECENTLY TOWARD KMGC-KVPZ. SOME POTENTIAL OF THUNDER WILL EXIST AT KSBN INTO THE EVENING HOURS AS REMNANT VORT MAX FROM ILLINOIS CONVECTION DROPS SOUTHEAST THROUGH WESTERN INDIANA. WITH BEST NEAR TERM POTENTIAL OF STORMS SOUTH AND WEST OF TERMINALS...WILL HOLD OFF ON INCLUSION WTIH THE 18Z TAFS. SETUP DOES APPEAR FAVORABLE FOR FOG AND STRATUS TO REDEVELOP OVERNIGHT...AND HAVE CONTINUED TREND OF PREVIOUS ISSUANCE TO IFR/LOWER END MVFR CONDITIONS OVERNIGHT. SLIGHTLY DRIER AIR TO ADVECT EASTWARD ON SUNDAY AND MID LEVEL RIDGE BUILDING INTO THE AREA SHOULD TEND TO DISCOURAGE THUNDER CHANCES FOR SUNDAY...WITH EAST WINDS OF 10 KNOTS OR LESS CONTINUING. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...MARSILI SYNOPSIS...FISHER SHORT TERM...FISHER LONG TERM...JT AVIATION...MARSILI VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
355 PM EDT SAT AUG 23 2014 .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 350 PM EDT SAT AUG 23 2014 19Z SFC ANALYSIS SHOWS OUR CONTINUING WEATHER CHALLENGE WITH THE LOW PRESSURE OUT TO THE WEST AND HIGH PRESSURE TO THE SOUTH. A WAVY NORTHWEST TO SOUTHEAST FRONT EXISTS JUST NORTH OF OUR AREA. MEANWHILE...ALOFT...A RIDGE IS FOUND THROUGH THE LOWER MIDSECTION OF THE NATION WITH A DIGGING TROUGH MOVING INTO THE MID ATLANTIC STATES. THIS PLACES CENTRAL AND EASTERN KENTUCKY IN THE TRACK OF ENERGY MOVING FROM THE UPPER MIDWEST INTO THE SOUTHERN APPALACHIANS TODAY. THESE FEATURES HAVE BEEN COMBINING LATELY TO PRODUCE CLUSTERS OF SHOWERS AND THUNDERSTORMS GENERALLY STARTING IN THE LATE AFTERNOON AND LASTING INTO THE EVENING. THE HIGH PW AIR IN PLACE OVER THE AREA...ALONG WITH THE DEWPOINTS PUSHING THE MID 70S...MAKES FOR PROLIFIC RAIN PRODUCING CELLS. AS HAS BEEN THE CASE REMAINS SO HEADING INTO LATE AFTERNOON...THOUGH THE AXIS OF CONCERN HAS SHIFTED SLIGHTLY WEST OWING TO THE WIGGLE OF THE RIDGE IN RESPONSE TO THE DIGGING TROUGH. CURRENTLY SCATTERED AND ISOLATED SHOWERS/STORMS ARE DOTTING THE CUMBERLAND VALLEY WITH SIGNS OF LARGER CLUSTERS STARTING TO TAKE SHAPE TO THE NORTHWEST. THOUGH DELAYED A BIT BY THE LOW STRATUS DECK FOLLOWING THE DENSE FOG THIS MORNING...TEMPERATURES HAVE CLIMBED SMARTLY INTO THE MIDDLE AND UPPER 80S THROUGH THE AREA AND WITH SUCH HIGH DEWPOINTS ARE YIELDING HEAT INDICES IN THE 95 TO 100 DEGREE RANGE. WINDS HAVE BEEN MAINLY LIGHT AND VARIABLE THROUGH THE AREA. THE MODELS ARE ALL IN PRETTY GOOD AGREEMENT ALOFT WITH THE WIGGLE WEST AND THEN BACK EAST OF THE UPPER RIDGE INTO MONDAY MORNING. SHORTWAVE ENERGY MOVING SOUTH BETWEEN THE UPPER SYSTEMS WILL PASS THROUGH CENTRAL AND EASTERN KENTUCKY TONIGHT WITH ONLY WEAKER PACKETS FORESEEN THROUGH THE REST OF THE WEEKEND. GIVEN THE AGREEMENT OF THE MODELS AND THE SMALLER SCALE NATURE OF CONVECTIVE ACTIVITY OF THIS REGIME HAVE AGAIN FAVORED THE HRRR AND NAM12 THROUGH THE FIRST 18 TO 36 HOURS AND A MODEL CONSENSUS AFTER THAT INTO MONDAY MORNING. SENSIBLE WEATHER WILL FEATURE ISOLATED AND SCATTERED CONVECTION AROUND EAST KENTUCKY THROUGH THE NEXT SEVERAL HOURS WITH AN DECENT POTENTIAL EVOLUTION OF STORMS INTO A LARGER SYSTEM LATER IN THE FIRST PART OF THE EVENING SOMEWHERE TO THE NORTHWEST. THE INGREDIENTS ARE THERE FOR ANOTHER ROUND OF SUCH STORMS AND THE EXCESSIVE RAINFALL THEY PRODUCE. STILL THE BEST INDICATIONS ARE THAT THE WORST OF ANY SUCH DEVELOPMENT WILL JUST BRUSH OUR SOUTHWESTERN COUNTIES WHERE WE ARE NOT QUITE AS SATURATED AS THE EAST. THIS IS GOOD NEWS...BUT GIVEN THE LOW FFG IN THE EAST JUST ABOUT ANY HEALTHY STORM THERE WILL PROMPT FLASH FLOODING CONCERNS. WITH THE STILL HIGH PWS AND INSTABILITY ACROSS THE ENTIRE AREA CANNOT CALL ANY PLACE FREE OF LOCALIZED FLASH FLOOD CONCERNS. THE ACTIVITY IS EXPECTED TO DIE DOWN LATER THIS EVENING AND WHEN COMBINED WITH AT LEAST PARTIAL CLEARING WILL LIKELY BRING ABOUT ANOTHER BLANKET OF FOG BECOMING DENSE IN AREAS TOWARD DAWN. WILL HIT THIS...IN ADDITION TO THE STORM/FLOOD CONCERNS...HARD IN THE HWO. ONCE THE FOG BURNS OFF ON SUNDAY...PARTLY SUNNY SKIES WILL AGAIN BUILD THE HEAT AND INSTABILITY THROUGH THE AREA WHILE LOWER PWS FOR MUCH OF THE AREA WILL LIMIT TO A SMALLER EXTENT FLASH FLOOD CONCERNS. EXPECT SOME COOLER AND...MORE IMPORTANTLY...DRIER AIR TO MAKE IT INTO THE EAST BY EVENING AS A BACK DOOR COLD FRONT PUSHES WEST THROUGH THE AREA ALLOWING SOME LOWS CLOSER TO NORMAL FOR THIS TIME OF YEAR IN THE FAR EAST BY DAWN MONDAY. AGAIN PATCHY FOG WILL BE A CONCERN DEPENDING ON THE RAINS OF THE PREVIOUS DAY AND CLEARING THAT NIGHT. STUCK WITH THE CONSSHORT AS A STARTING POINT FOR THE T/TD/WINDS THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND SUNDAY NIGHT. AS FOR POPS...ENDED UP CLOSER TO THE WETTER MET GUIDANCE TONIGHT AND THEN NEARER THE MAV NUMBERS FOR THE REST OF THE SHORT TERM PORTION OF THE FORECAST. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 239 PM EDT SAT AUG 23 2014 STRONG RIDGING WILL DOMINATE THE EASTERN CONUS THROUGH NEXT WEEK WITH SUMMER-LIKE WEATHER CONTINUING. FORTUNATELY...WITH A STRONGER CAP PRESENT...CONVECTION WILL BE HELD MORE AT BAY. CANNOT RULE OUT A STRAY AFTERNOON SHOWER OR STORM EACH DAY...BUT SHOULD BE NOTHING LIKE WE HAVE SEEN LATELY. PLANNING TO GO WITH A DIURNAL TREND WITH POPS THROUGH THE END OF THE PERIOD WITH POPS PEAKING EACH AFTERNOON WITH MAXIMUM HEATING/INSTABILITY. A SURFACE TROUGH MAY APPROACH FROM THE WEST EARLY NEXT WEEKEND...BUT A TROPICAL SYSTEM DEVELOPING OVER THE ATLANTIC BASIN...MAY HAVE A TENDENCY TO SLOW DOWN THE ADVANCEMENT OF THIS FEATURE UNTIL SOMETIME LATE IN THE WEEKEND OR THE FOLLOWING WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 200 PM EDT SAT AUG 23 2014 SCATTERED SHOWERS AND THUNDERSTORMS WILL BE A CONCERN INTO THE EVENING FOR ALL SITES...THOUGH THE BEST CHANCES WILL BE HAD AT LOZ AND SME. WITH ANY STORMS...EXPECT LOWER CIGS...INTO THE MVFR RANGE...AND A POTENTIAL FOR IFR VIS. OTHERWISE...VFR WILL PREVAIL INTO THE EVENING. THE AMPLE BOUNDARY LAYER MOISTURE AND PARTIAL CLEARING EXPECTED TONIGHT SHOULD SET THE STAGE FOR ROBUST FOG DEVELOPMENT THROUGH THE ENTIRE AREA. ACCORDINGLY HAVE BROUGHT IN DENSE...VLIFR...FOG AT ALL SITES LATE TONIGHT. THE FOG BURNS OFF BY 14Z SUNDAY WITH VRF CONDITIONS ANTICIPATED AHEAD OF SCATTERED STORM DEVELOPMENT IN THE AFTERNOON FOR WESTERN PARTS OF THE AREA. WINDS THROUGH THE PERIOD WILL BE MAINLY LIGHT AND VARIABLE. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...KAS AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
242 PM EDT SAT AUG 23 2014 .SYNOPSIS... A FRONTAL BOUNDARY ACROSS THE MID ATLANTIC STATES WILL MOVE SOUTHWEST OF THE AREA TODAY. HIGH PRESSURE FROM NEW ENGLAND SLOWLY BUILDS INTO THE AREA TONIGHT INTO SUNDAY...BEFORE SETTLING OVER THE PIEDMONT EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE HRRR AND RUC ALL INDICATE THE SHOWERS OVER THE SW PART OF THE CWA WILL CONTINUE SE AND EXIT THE AREA BY EARLY AFTERNOON. OTHER SHOWERS OVER MD WILL MOVE INTO THE NORTHERN NECK AND THE DELMARVA DURING THE EARLY AFTERNOON. THESE WILL BE WEAKENING AS THEY ENCOUNTER DRIER AIR. HAVE RAISED POPS SOME ALONG THE LINES OF BOTH AREAS OF SHOWERS. ALSO HAVE LOWERED THE MAX TEMPERATURE A LITTLE AS NOT MUCH SUNSHINE TODAY AND WITH WINDS COMING OFF THE OCEAN WILL HELP TO KEEP TEMPERATURES LOWER. PREVIOUS DISCUSSION...LATEST SFC ANALYSIS REVEALS HI PRES CENTERED OVR NEW ENGLAND AND A DISORGANIZED PRES FIELD OVR THE MID ATLANTIC REGION COINCIDING WITH A WEAK STALLED FRNTAL BNDRY. ALOFT...NW FLOW CONTINUES WITH AN UPR-LEVEL RIDGE CENTERED OVR THE E-CNTRL CONUS. THE SFC FRNT WILL SAG S INTO THE CAROLINAS TDA. EXPECT ANOTHER DAY WITH SCT SHRAS/TSTMS...ESPECIALLY OVR THE PIEDMONT CLOSER TO THE FRNT. THE POTENTIAL FOR THUNDER WILL BE CONFINED AWAY FROM THE CSTS DUE TO NE FLOW WITH HI PRES BLDG OVR NEW ENGLAND. NOT EXPECTING ANY SVR WX BUT HEAVY RAIN IS PSBL IN SOME AREAS. AFTN HI TEMPS WILL RANGE FM THE UPR 70S TO NEAR 80 OVR THE LWR ERN SHORE TO THE LO-MID 80S ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... THE HIGH SURGES SSW OVER THE AREA TONIGHT INTO SUNDAY WITH THE SURFACE RIDGE AXIS SETTLING OVER THE PIEDMONT BY MONDAY. THIS WILL PRODUCE A DRYING TREND ALONG WITH A NE WIND THAT SHOULD BE RATHER BREEZY ALONG THE COAST. PARTLY TO MOSTLY SUNNY CONDITIONS ARE EXPECTED BY SUNDAY...WITH MOSTLY CLEAR/SUNNY CONDITIONS BY SUNDAY NIGHT AND MONDAY. HIGHS WILL BE BELOW SEASONAL AVERAGES THROUGH MONDAY (AROUND -1 ST DEV). HIGHS SUNDAY AND MONDAY WILL RANGE FROM THE UPPER 70S TO LOW 80S. LOWS SHOULD BE IN THE MID/UPPER 60S SUNDAY MORNING...WITH MAINLY LOW/MID 60S EXPECTED MONDAY MORNING. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... SFC HIGH PRESSURE AND UPPER LEVEL RIDGING ALONG THE EASTERN SEABOARD IS EXPECTED TO CONTINUE THROUGH MID NEXT WEEK. THIS PATTERN WILL MAINTAIN A COOLER AIRMASS OVER THE AREA THROUGH WED BEFORE THE RIDGE AXES AT THE SFC AND ALOFT ALOFT BEGIN TO SHIFT JUST EAST OF THE FA...AND MOVING OFFSHORE BY THU. THE FORECAST IS GENERALLY DRY THROUGH THE EXTENDED FORECAST PERIODS DUE TO WELL-ESTABLISHED SUBSIDENCE THROUGH THE ATMOSPHERIC PROFILE...HOWEVER A FEW SHOWERS CANNOT BE RULED OUT NEAR THE FAR SE VA/NE NC COAST ON WED DUE TO THE POTENTIAL FOR WRAPAROUND MOISTURE FROM THE TROPICAL SYSTEM PASSING WELL TO THE EAST. HIGH AND LOW TEMPERATURES WILL RUN BELOW NORMAL FROM MON NIGHT THROUGH WED NIGHT (LOWS IN THE 60S...UPPER 50S FAR WRN COUNTIES/HIGHS IN THE LOW-MID 80S...MID-UPPER 70S BEACHES) AND THEN REBOUND TWD SEASONAL NORMALS THU/THU NIGHT (HIGHS IN THE MID-UPPER 80S...UPPER 70S-LOWER 80S BEACHES/LOWS IN THE MID-UPPER 60S...AROUND 70 BEACHES). && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... MVFR SHOWERS AND CEILINGS WILL PERSIST OVERNIGHT DUE TO THE SATURATED AIRMASS ACROSS THE AREA. HIGH PRESSURE TO THE NORTH WILL CONTINUE TO BUILD SOUTH PUSHING DRIER AIR INTO THE MID-ATLANTIC. THIS WILL HELP CLEAR THE SHOWERS AND CEILINGS BY SUNDAY MORNING. EXPECT VFR CONDITIONS TO PREVAIL SUN AFTN WITH A CONTINUED NE WIND. OUTLOOK...DRY WEATHER IS FORECAST FOR SEVERAL DAYS BEGINNING SUNDAY AS MID AND LOWER RIDGING TAKES PLACE OVER THE AREA. && .MARINE... FRONTAL BOUNDARY NOW SOUTH OF THE AREA WITH HIGH PRESSURE BUILDING SOUTH FROM NEW ENGLAND. DESPITE THE ONGOING E-NE WINDS...LATEST GUIDANCE NOT AS BULLISH WITH THE WINDS THUS CREATING SOME DOUBT WHEN SCA CONDITIONS WILL START. TOUGHEST CALL WILL BE SOUTHERN CHES BAY WHERE ONLY MINIMAL CONDITIONS WILL BE MEET. MOUTH OF THE BAY WILL HAVE AN EARLIER START AND LATER FINISH TIME. SEAS (ESPECIALLY OUT NEAR 20 NM) ARE EXPECTED TO BUILD TO 5 FEET THEN REMAIN THERE THROUGH EARLY NEXT WEEK...SO EXTENDED THE SCA HEADLINES OVR THE WATERS THRU SUNDAY NIGHT. FOR CONTINUITY SAKE...WENT AHEAD AND HOISTED SCA HEADLINES FOR CURRITUCK SND SUN AND SUN NIGHT AS SCNDRY SURGE WILL LIKELY KEEP WINDS BTWN 15-20 KTS. FORECAST NEXT WEEK WILL DEPEND ON THE TRACK OF A DEVELOPING (TROPICAL) LOW PROGGED TO TRACK NE BUT REMAIN EAST OF GULF STREAM WALL. SWELL FROM THIS SYSTEM WILL EVENTUALLY AFFECT THE MID ATLNTC BEACH AREAS. && .TIDES/COASTAL FLOODING... TIDES PROGGED TO BUILD TO ABOUT 1 FOOT ABOVE NORMAL EARLY NEXT WEEK AS THE NE FLOW CONTINUES. DESPITE THE PERSISTENT ONSHORE FLOW...LEVELS EXPECTED TO REMAIN ABOUT 1/2 FOOT BELOW MINOR FLOODING THRESHOLDS. WENT WITH A MODERATE RIP CURRENT THREAT TODAY GIVEN NEARSHORE WAVES OF 2-3 FT AND A INCREASING NE WIND FLOW. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR MDZ025. NC...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR NCZ102. VA...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR VAZ098>100. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 2 AM EDT MONDAY FOR ANZ634. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 PM EDT SUNDAY FOR ANZ632. SMALL CRAFT ADVISORY FROM 8 AM SUNDAY TO 6 AM EDT MONDAY FOR ANZ633. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT MONDAY FOR ANZ654. SMALL CRAFT ADVISORY FROM 2 AM SUNDAY TO 6 AM EDT MONDAY FOR ANZ656-658. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT MONDAY FOR ANZ650-652. && $$ SYNOPSIS...AJZ/MAS NEAR TERM...MAS/JAB SHORT TERM...AJZ/MAS LONG TERM...BMD AVIATION...DAP MARINE...MPR TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS GAYLORD MI
405 PM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 405 PM EDT SAT AUG 23 2014 HIGH PRESSURE TO OUR EAST WILL PROVIDE FOR LIGHT SOUTHERLY BREEZES...AND INCREASING WARMTH AND HUMIDITY THROUGH MONDAY. FOR THE MOST PART THE WEEKEND LOOKS DRY...BUT SHOWERS AND THUNDERSTORM CHANCES WILL INCREASE ON MONDAY...AHEAD OF A WEAK COLD FRONT THAT WILL ENTER NORTHERN MICHIGAN MONDAY NIGHT. && .SHORT TERM...(THIS EVENING THROUGH TONIGHT) ISSUED AT 405 PM EDT SAT AUG 23 2014 SHARP MID LEVEL RIDGE AXIS CONTINUES TO POKE UP INTO THE WESTERN GREAT LAKES ROUGHLY FROM EASTERN WISCONSIN UP THROUGH CENTRAL UPPER MICHIGAN...DOWNSTREAM OF STRONG SHORT WAVE TROUGHING ACROSS THE NRN ROCKIES INTO THE NRN PLAINS. BROAD LOW PRESSURE ACROSS THE CENTRAL PLAINS WITH A SFC WARM FRONT DRAPED ACROSS MISSOURI INTO THE OHIO RIVER VALLEY. ELEVATED WARM FRONT AND THETA-E PLUME HAS SPREAD NORTHWARD ACROSS THE MIDWEST INTO THE LOWER GREAT LAKES AND CONTINUES TO BE THE MAIN WEATHER FOCUS WITH YET ANOTHER ROUND OF CONVECTION WORKING ACROSS THE MIDWEST THIS AFTERNOON. ACROSS THE NRN GREAT LAKES...WEAK HIGH PRESSURE IS DRAPED ACROSS NRN MICHIGAN. BUT...SUBTLE LOW-MID LEVEL TROUGH AXIS ANALYZED ACROSS WESTERN/CENTRAL UPPER MICHIGAN ALONG NE FRINGE OF DEEPER MOISTURE GRADIENT...WHERE RUC ANALYSIS CONTINUES TO DEPICT A STRONG LOW-MID LEVEL DEFORMATION AXIS STRETCHING FROM NRN LAKE MICHIGAN UP THROUGH CENTRAL UPPER MICHIGAN. THIS HAS/IS GENERATING A BAND OF SHOWERS UP THROUGH THAT AREA PARTICULARLY AROUND THE ESCANABA AREA (TERRAIN INFLUENCED) TRYING TO BLEED ACROSS NRN LAKE MICHIGAN ALTHOUGH PRECIP APPEARS TO FINALLY BE WINDING DOWN. SOME HEATING INDUCED CONVECTION ALSO ONGOING IN NE WISCONSIN WITHIN THE BETTER MOISTURE FIELD. ACROSS NRN LOWER MICHIGAN...STUBBORN LAKE STRATUS IN EASTERN UPPER AND NE LOWER MICHIGAN HAS MOSTLY MIXED OUT INTO A FLAT CU FIELD. NO SIGNS OF ANY PRECIP. BUT SOLID LAKE STRATUS REMAINS LOCKED ACROSS WESTERN LAKE HURON INTO THE STRAITS...SIGNS OF THINGS TO COME I THINK. TONIGHT...NO PRECIP AS MAIN FOCUS WILL REMAIN WEST-THROUGH-SOUTH OF NRN MICHIGAN. WILL ENJOY A FEW HOURS OF CLR TO PARTLY CLOUDY SKIES THIS EVENING AS HEATING INDUCE CU/STCU DECK FADES AWAY. BUT WITH PERSISTENT EASTERLY FLOW JUST OFF THE DECK...VEERING SOUTHEAST OVERNIGHT...SUSPECT MARINE LAYER/LAKE STRATUS AND FOG OUT ACROSS LAKE HURON WILL ONCE AGAIN GET SCOOPED INTO EASTERN UPPER MICHIGAN AND NORTHEAST LOWER MICHIGAN DURING THE OVERNIGHT HOURS. HAVE TAILORED THE FORECAST THAT WAY ALONG WITH PATCHY TO AREAS OF FOG OVERNIGHT. A REPEAT ON TEMPS WITH A BIT OF A MUGGY NIGHT (RELATIVELY SPEAKING) AND LOWS IN THE UPPER 50S TO MIDDLE 60S. && .LONG TERM...(SUNDAY THROUGH SATURDAY) ISSUED AT 405 PM EDT SAT AUG 23 2014 ...WARM START...COOLER FINISH TO THE UPCOMING WEEK... HIGH IMPACT WEATHER POTENTIAL: MINIMAL. SOME THUNDER POTENTIAL AT TIMES THIS WEEK. PATTERN SYNOPSIS/ANTICIPATED EVOLUTION: AMPLIFIED PATTERN SOO TALKED ABOUT THE LAST SEVERAL DAYS LOOKS TO REACH MATURATION SUNDAY...WHEN MOST IMPRESSIVE RIDGE AXIS/HEAT DOME OF THIS SUMMER BUILDS DIRECTLY OVERHEAD AND UP INTO SOUTHEAST CANADA. WESTERN TROUGHING CONTINUES...WITH LEAD EJECTING RATHER ROBUST SHORTWAVE LOOKING TO PUT A KIBOSH ON FURTHER RIDGE AMPLIFICATION HEADING INTO THE START OF NEXT WORK WEEK. PATTERN THERE-ON-AFTER LOOKS TO BECOME AN INCREASINGLY FLATTER ONE AS STRONGEST CORES OF UPPER LEVEL JET ENERGY SLICE WEST/EAST ACROSS SOUTHERN CANADA. A CHANGEABLE PATTERN FOR SURE...AND ONE THAT SIMPLE FORCES ANOTHER EXTENDED STRETCH OF LOW CONFIDENCE SHOWER AND STORM FORECAST EVOLUTION. PRIMARY FORECAST CONCERNS/CHALLENGES: JUST HOW WARM TO GO SUNDAY/MONDAY AND ADDRESSING WHAT INITIALLY LOOKS TO BE MULTI-PERIOD SHOWER AND THUNDERSTORM CHANCES RIGHT THROUGH THE WEEK. DETAILS: TAKE TODAY`S WEATHER...TACK ON A FEW DEGREES...SUNDAYS WEATHER DONE! MORE SIGNIFICANT CHANGES TAKE PLACE MONDAY AS RIDGE APEX PUSHES EAST AND EARLIER MENTIONED SHORTWAVE PUNCHES UP INTO SOUTH CENTRAL CANADA. SOUTHWEST FLOW RAMPS UP IN RESPONSE...DRIVING A GOOD CHUNK OF CURRENT SOUTHERN PLAINS HEAT DOME ALONG WITH IT. H8 TEMPS MAKE A RUN INTO THE UPPER TEENS...READINGS NOT YET SEEN AROUND THESE PARTS THIS SUMMER. INCREASING PRESSURE GRADIENT ON FRONT SIDE OF APPROACHING/ALBEIT STEADILY DECAYING/COLD FRONT SHOULD ONLY HELP THE SURFACE WARMING CAUSE. TEMPERATURES WELL INTO THE 80S A SURE BET FOR AREAS SOUTH OF THE BIG BRIDGE...AND NOT OUT OF THE REALM OF POSSIBILITY A FEW FAVORED DOWNSLOPE AREAS OF NORTHEAST LOWER MAKE A RUN A 90. NOW...THAT SAME FRONT MAY BRING A SHOWER AND STORM THREAT ALONG WITH IT. DEFINITELY NOT ENTIRELY SOLD ON THIS IDEA GIVEN FAR REMOVED MID LEVEL SUPPORT AND QUICKLY DECAYING FORCED SURFACE CONVERGENCE. ATMOSPHERE ALSO HAS THE LOOK OF BEING RATHER CAPED...WITH NOTED H8 WARM NOSE. WHILE OVERALL AIRMASS BECOMES INCREASINGLY MOIST...SET-UP SCREAMS OF DECENT LOW LEVEL MIXING OUT OF MOISTURE...AND STARTING TO WONDER IF PROGGED UPPER 60 DEWPOINTS ARE SEVERAL DEGREES TOO HIGH. NO DOUBT ABOVE LEAVES PLENTY OF OPPORTUNITY FOR A DRY LATE MONDAY FRONTAL PASSAGE. INHERITED LOW CHANCES WILL DO FOR NOW...BUT TRULY BELIEVE MANY WILL SEE LITTLE...IF ANY...RAIN. SAID FRONT LOOKS TO SIGNIFICANTLY SLOW ITS SOUTH PROGRESS MONDAY NIGHT THROUGH TUESDAY NIGHT AS IT BECOMES INCREASINGLY ALIGNED WITH DEEP LAYER WESTERLY FLOW. JUST WHERE IT STALLS OUT IS OPEN TO PLENTY OF DEBATE...BUT GIVEN BREADTH OF PREFRONTAL WARMING AND TOTAL DETACHMENT OF ANY MID LEVEL SUPPORT...KINDA FEEL IT MAY STRUGGLE TO CLEAR OUR SOUTHERN COUNTIES UNTIL SOMETIME TUESDAY NIGHT. NOW...THAT LEADS TO A TRICKY TEMPERATURE AND SHOWER FORECAST RIGHT THROUGH MID WEEK. AS FOR TEMPERATURES...TUESDAY HAS THE POTENTIAL TO BE DOWNRIGHT WARM...ESPECIALLY FOR AREAS NEAR SAGINAW BAY...WHERE TEMPERATURES MAY ONCE AGAIN REACH INTO THE MID AND UPPER 80S. COOLER AIR ARRIVES WEDNESDAY...WITH HIGHS MOSTLY IN THE 70S (ALL DEPENDENT ON THAT WHOLE FRONTAL TIMING THING OF COURSE). NEARLY ALL GUIDANCE REMAINS STEADFAST ON ADDITIONAL SHOWER/STORM DEVELOPMENT ALONG AND NORTH OF THE SURFACE FRONT AS WEAK MID LEVEL IMPULSES RIDE ALONG IT MONDAY NIGHT RIGHT INTO WEDNESDAY. ANY DECENT SUPPORT IS FAR FROM CERTAIN...AND JUST NOT BUYING THIS WET LOOK IN GUIDANCE. MUCH LIKE MONDAY...LOWER POPS THE WAY TO GO FOR NOW...WITH PLENTY OF TIME TO WORK ON BETTER TEMPORAL AND SPATIAL RESOLUTION OF SHOWER/STORM CHANCES IN THE COMING DAYS. SOME HINTS WHAT IS LEFT OF WESTERN TROUGHING GETS SHUNTED EAST LATE IN THE WEEK...FORCING FRONT BACK NORTH AND DRUMMING UP ADDITIONAL RAIN CHANCES TO START NEXT WEEKEND. TIMING WILL CHANGE...AND A SIMPLE CONSENSUS BLEND APPROACH WILL BE UTILIZED FOR NOW....WHICH INDEED HOLDS OFF NEXT MENTION FOR SHOWERS/STORMS UNTIL FRIDAY NIGHT AND SATURDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 132 PM EDT SAT AUG 23 2014 STUBBORN STRATUS DECK FLOWING OFF LAKE HURON ON EASTERLY WINDS CONTINUES TO BRING MVFR FLIGHT CONDITIONS TO PLN/APN...ALTHOUGH STRATUS DECK HAS/IS SLOWLY ERODING. CLOUDS SHOULD SCATTER OUT BY MID TO LATE AFTERNOON AT THOSE SITES LEAVING A PERIOD OF VFR CONDITIONS HEADING INTO THE EVENING. VFR CONDITIONS AT TVC AND MBL WILL PERSIST. TONIGHT...FEAR CYCLE WILL REPEAT AS MARINE STRATUS ONCE AGAIN REDEVELOPS OFF THE LAKE INTO NE LOWER MICHIGAN...LATER THIS EVENING AND FOR THE OVERNIGHT HOURS WITHIN PERSISTENT E/SE FLOW. THUS...HAVE IFR CIGS AND LOW VSBYS ONCE AGAIN TAKING OFF AT APN/PLN THROUGH THE COURSE OF THE NIGHT WHILE TVC/MBL REMAIN LARGELY VFR WITH SOME MINOR REDUCTIONS TO VSBY DUE TO LIGHT FOG. WINDS...LIGHT EASTERLY TODAY...CALM TONIGHT AND LIGHT SE ON SUNDAY. && .MARINE... ISSUED AT 405 PM EDT SAT AUG 23 2014 ABUNDANT MARINE STRATUS AND FOG WILL CONTINUE TO IMPACT THE NEARSHORE AREAS OF NRN LAKE HURON INTO THE SAINT MARYS RIVER SYSTEM...TONIGHT INTO SUNDAY BEFORE STRONGER SOUTHERLY WINDS DEVELOP LATER SUNDAY INTO MONDAY AND FINALLY SCOURS OUT THE STRATUS/FOG. OTHERWISE...LIGHT EASTERLY WINDS TONIGHT WILL VEER MORE SOUTHEASTERLY THEN SOUTH ON SUNDAY...INCREASING SUNDAY NIGHT INTO MONDAY. MAY DEVELOP ENOUGH GUSTINESS TO WARRANT SMALL CRAFT ADVISORIES FOR PARTS OF NRN LAKE MICHIGAN BY MONDAY MORNING...ALTHOUGH LAKE STABILITY MAY KEEP WINDS/WAVES IN CHECK. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ SYNOPSIS...AM SHORT TERM...ADAM LONG TERM...MSB AVIATION...ADAM MARINE...ADAM
AREA FORECAST DISCUSSION
NWS GAYLORD MI
133 PM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 246 AM EDT SAT AUG 23 2014 HIGH PRESSURE TO OUR EAST WILL PROVIDE FOR LIGHT SOUTHERLY BREEZES...AND INCREASING WARMTH AND HUMIDITY THROUGH MONDAY. FOR THE MOST PART THE WEEKEND LOOKS DRY...BUT SHOWERS AND THUNDERSTORM CHANCES WILL INCREASE ON MONDAY...AHEAD OF A WEAK COLD FRONT THAT WILL ENTER NORTHERN MICHIGAN MONDAY NIGHT. && .UPDATE... ISSUED AT 1111 AM EDT SAT AUG 23 2014 SHARP MID LEVEL RIDGE AXIS CONTINUES TO POKE UP INTO THE WESTERN GREAT LAKES...DOWNSTREAM OF STRONG SHORT WAVE TROUGHING ACROSS THE NRN ROCKIES INTO THE NRN PLAINS. BROAD LOW PRESSURE ACROSS THE CENTRAL PLAINS WITH A SFC WARM FRONT DRAPED ACROSS THE MIDWEST INTO THE OHIO VALLEY...AND CONTINUES TO BE THE MAIN WEATHER FOCUS WITH YET ANOTHER ROUND OF CONVECTION IN THE MIDWEST. ACROSS NRN MICHIGAN...A BUNCH OF LITTLE THINGS HAPPENING. WEAK HIGH PRESSURE IS DRAPED ACROSS NRN MICHIGAN. BUT...SUBTLE LOW-MID LEVEL TROUGH AXIS ANALYZED ACROSS WESTERN/CENTRAL UPPER MICHIGAN ALONG NE FRINGE OF DEEPER MOISTURE GRADIENT...WHERE RUC ANALYSIS REVEALS A STRONG LOW-MID LEVEL DEFORMATION AXIS STRETCHING FROM NRN LAKE MICHIGAN UP THROUGH CENTRAL UPPER MICHIGAN. THIS IN TURN HAS/IS GENERATING A BAND OF SHOWERS UP THROUGH THAT AREA. ONE POCKET OF RAIN IN PARTICULAR HAS SEEMINGLY LATCHED ON TO THE TERRAIN INCREASE OFF LAKE MICHIGAN AND HAS BROUGHT SOME LOCALLY HEAVY RAIN THROUGH THAT AREA. NOTHING LIKE THAT HAPPENING HERE. BUT...BATCH OF VERY STUBBORN STRATUS CONTINUES TO FLOW OFF LAKE HURON WITHIN EASTERLY FLOW...BRINGING CLOUDY SKIES TO PARTS OF EASTERN UPPER AND NE LOWER MICHIGAN. STRATUS IS BEGINNING TO ERODE...BUT PROCESS IS TAKING IT/S TIME. REST OF TODAY...STRATUS IN THE EAST AND IN EASTERN UPPER MICHIGAN WILL EVENTUALLY ERODE/MIX OUT...BUT IT WILL TAKE SEVERAL MORE HOURS AS EAST FLOW CONTINUES TO PUMP COOL/MOIST MARINE AIR INTO THOSE AREAS. HAVE STRETCHED CLOUDY SKIES OUT FOR SEVERAL MORE HOURS. ELSEWHERE...HEATING INDUCED CLOUD COVER SHOULD DEVELOP OVER NW LOWER MICHIGAN AND WE MAY SEE SOME OF THAT AFOREMENTIONED DEFORMATION CLOUD COVER EXPAND DOWN INTO NW LOWER MICHIGAN AS WELL. SO... EITHER CLOUDY BECOMING PARTLY SUNNY...OR SUNNY BECOMING PARTLY SUNNY WILL BE THE NAME OF THE GAME THIS AFTERNOON. TEMPS WILL OF COURSE BE TRICKY GIVEN THE CLOUDS...AND AREAS EAST OF I-75 WILL END UP WITH THE LOWER READINGS AND HAVE TWEAKED MAX TEMPS ACCORDINGLY. BUT...IT WILL NOT TAKE MUCH FOR TEMPS TO REBOUND WHEN THE SUN FINALLY DOES BREAK OUT. JUST HOPE WE DON/T GET SOME SORT OF DIFFERENTIAL HEATING BOUNDARY ACROSS NRN LOWER/EASTERN UPPER MICHIGAN THAT POPS OFF CONVECTION THIS AFTERNOON. THINK WE ARE TOO CAPPED FOR THAT...BUT WILL SEE. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 246 AM EDT SAT AUG 23 2014 HIGH IMPACT WEATHER POTENTIAL: MINIMAL PRIMARY FORECAST CHALLENGES: DO SHOWERS MOVE INTO NORTHERN MICHIGAN? CURRENTLY, AS WAS MENTIONED AT THE EARLIER UPDATE, RAIN SHOWERS UPSTREAM OF THE FORECAST AREA ARE JUST SOUTH OF MQT AND SAW AND ALONG THE 700 MB DEWPOINT DEPRESSION GRADIENT, AND IN THE LFQ OF THE 500 MB 30 KNOT JET STREAK MOVING THROUGH N WISCONSIN. MAIN FORCING THAT IS GOING ON OVERNIGHT IS OVER FARTHER SOUTH AND WEST IN NEBRASKA WHERE THE DEEPER SFC LOW AND 500 MB VORT AND SPEED MAXES ARE DIGGING. THIS HAS GIVEN RISE TO THE COMPLEX OF STORMS IN THE CENTRAL PLAINS. THE SFC LOW IN THE E COLORADO IS LINKED BY A SLOWLY STRENGTHENING FRONT THAT STRETCHES TO THE NE THROUGH N MINNESOTA AND UP INTO JAMES BAY TO A WEAKER SFC LOW. TODAY...THE MODELS ARE IN GOOD AGREEMENT WITH THE RUC/NAM12/GFS/ECMWF/LOCAL WRF4KM SHOWING THE MORNING ISOLATED SHOWERS THAT WILL TRY TO PUSH INTO NW LOWER THIS MORNING. HOWEVER, AS THE 500 MB RIDGE OVER THE UPPER GREAT LAKES CONTINUES TO AMPLIFY, THE FORCING FOR THE SHOWERS WILL GET PUSHED TO THE NORTH AND WEST THROUGH THE AFTERNOON. THE FRONT WILL ALSO MOVE TO THE NORTH AND WEST AS THE SFC LOW IN E COLORADO MOVES OUT OVER THE CENTRAL PLAINS AND DEEPENS. THIS WILL HELP TO FOCUS MOST OF THE RAIN INSTABILITY AND THE DYNAMIC SUPPORT OVER THE NORTHERN PLAINS AS DEPICTED BY SPC. TONIGHT...THIS MOVEMENT OF THE SFC LOW OUT OF THE CENTRAL PLAINS WILL PUSH INTO NORTH DAKOTA OVERNIGHT CONTINUING TO PULL THE FOCUS AWAY FROM THE UPPER GREAT LAKES. THIS SHOULD CONTINUE OUR RAIN FREE STREAK (OR AT LEAST OUR MEASURABLE PRECIPITATION) THROUGH THE NIGHT. WHILE THERE IS SOME INSTABILITY, THE LACK OF A FOCUS AND THE CAPPING EXPECTED IN THE EVENING (BLAYER CIN 20-40 J/KG) SHOULD INHIBIT ANY SHOWERS FROM GETTING GOING. IT DOESN`T LOOK LIKE THERE IS MUCH IN THE WAY OF ELEVATED INSTABILITY AS THE SHOWALTER INDEX OVER N MICHIGAN AT ITS LOWEST IS ONLY +2C. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 246 AM EDT SAT AUG 23 2014 A HIGHLY AMPLIFIED 500MB RIDGE WILL BE OVERHEAD TO START OUR SUNDAY. AN EJECTING UPPER LOW FROM THE NORTHERN HIGH PLAINS WILL HAVE TO CREST THIS RIDGE...AND WILL PASS WELL TO OUR NORTH MONDAY NIGHT. THIS WILL FLATTEN OUT THE RIDGE...THOUGH IN OUR NECK OF THE WOODS 500MB HEIGHTS WILL HARDLY LOWER AT ALL. STILL...AN ASSOCIATED COLD FRONT WILL SLOWLY GET DRAGGED INTO THE AREA MONDAY NIGHT. UNTIL THAT HAPPENS...IT WILL BE SOMETHING OF A CHALLENGE TO GET A PRECIP THREAT GOING IN THESE PARTS. BUT IT WON/T BE CHALLENGING TO BECOME INCREASINGLY WARM AND HUMID. SUNDAY...CORE OF THE 500MB RIDGE STARTS TO SLIDE DOWNSTREAM IN THE AFTERNOON. THAT CORRESPONDS WITH A SLIGHT UPTICK IN 1000-850MB RETURN FLOW. HOWEVER...A SHORTWAVE RIDGE ASCENDING INTO THE LARGER RIDGE WILL HELP KEEP HEIGHTS HIGH. AT THE SAME TIME...SURFACE HIGH PRESSURE TO OUR EAST WILL STILL EXTEND A TOUCH OF RIDGING INTO NORTHERN MI. FROM A CONCEPTUAL MODEL STANDPOINT...IT WILL BE DIFFICULT TO FIRE OFF CONVECTION IN THIS PATTERN UNTIL HEIGHTS ALOFT FALL. INDEED...THE MODELS ARE NOT INCLINED TO PROG MUCH IF ANY CAPE. 00Z NAM HAS A LATE-DAY AXIS OF A FEW HUNDRED J/KG OF MUCAPE... HUGGING THE LAKE MI COAST FROM LTL TRAV BAY SOUTH. THIS IS WHERE LAKE BREEZE CONVERGENCE AND MOISTURE POOLING WILL BE CONCENTRATED... THANKS TO A BACKGROUND LIGHT SE SYNOPTIC SURFACE WIND. EVEN SO...AN 82/65 PARCEL HAS ABOUT 50J/KG OF CIN TO OVERCOME...THANKS TO 700MB TEMPS AROUND 9C. SO WILL MAINTAIN A DRY FORECAST. CAN GENERALLY EXPECT PARTLY SUNNY SKIES...WILL SOME BUBBLY CU AND MID/HIGH DEBRIS CLOUDS (INSTABILITY WILL BE MUCH HIGHER W OF LAKE MI). MAX TEMPS UPPER 70S (EASTERN UPPER...AND NE LOWER COAST)...TO LOW/MID 80S (INTERIOR SW SECTIONS). SUN NIGHT/MONDAY...SUB-850MB FLOW MAINTAIN AN EASTERLY COMPONENT INTO THE EVENING...BEFORE VEERING S TO EVEN SSW OVERNIGHT. THAT WILL ALLOW A JUICIER AND POTENTIALLY UNSTABLE AIRMASS TO FINALLY MAKE INROADS. HOWEVER...THAT WILL BE SLOW AT 1ST...WITH PERHAPS WESTERN CHIP/MACK THE ONLY PLACE PROGGED TO SEE SOME CAPE ARRIVE BY MORNING. THIS COULD ALLOW CONVECTION ORIGINATING IN WI A CHANCE TO GRAZE BY THAT AREA OVERNIGHT. BUT...GIVEN THE MODELS TEND TO BE TOO QUICK TO BREAK DOWN RIDGING AND CIN...WILL MAINTAIN A DRY FORECAST FOR SUN NIGHT. DEEP MOISTURE/MODERATE INSTABILITY PLUME WILL VERY SLOWLY WORK IN FROM THE WNW MONDAY...AHEAD OF A COLD FRONT ADVANCING ACROSS WI. HEIGHTS/TEMPS ALOFT HERE REMAIN HIGH...BUT ACTIVITY SHOULD DEVELOP UPSTREAM IN WI AND MOVE E AND NE TOWARD WESTERN/NORTHERN SECTIONS...ESPECIALLY LATER IN THE DAY. WILL MAINTAIN CHANCE POPS BY AFTERNOON IN THE NW 2/3DS OF THE FORECAST AREA...INCLUDING HIGH CHANCE (50) POPS IN WESTERN CHIP/MACK. MIN TEMPS NEAR 60F TO THE MID 60S. MAX TEMPS NEAR 80 TO THE MID 80S...A FEW UPPER 80S POSSIBLE IN THE INTERIOR OF NORTHERN LOWER. DEW POINTS WILL BE RISING INTO THE MID AND UPPER 60S...SO IT WILL ALSO BE QUITE STICKY ON MONDAY. REST OF THE FORECAST...SHAPING UP FOR A FAVORABLE MCS PATTERN MID-WEEK. A STALLED FRONTAL ZONE (AND A WARM/HUMID AIRMASS) WILL BE JUST TO OUR SOUTH...WITH FAST ZONAL FLOW IN THE NORTHERN LAKES. CONSALL GRIDS ARE TRYING TO NUDGE US TOWARD LIKELY POPS IN SOME PERIODS. AM BACKING AWAY FROM THIS THINKING GIVEN THAT IT/S CONVECTION WE/RE TALKING ABOUT...AND PRECIP HAS UNDERPERFORMED OVER THE LAST WEEK OR SO. TEMPS WILL BE DRIFTING BACK TOWARD OR A BIT UNDER CLIMO BY LATE IN THE WORK WEEK...THOUGH PROBABLY NOT AS COOL AS THE GFS/MEX GUIDANCE ADVERTISES...AS THE ECMWF IS SLOWER AND LESS AMPLIFIED WITH THE UPPER TROF THAT PROGRESSES INTO THE PLAINS STATES MID/LATE WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 132 PM EDT SAT AUG 23 2014 STUBBORN STRATUS DECK FLOWING OFF LAKE HURON ON EASTERLY WINDS CONTINUES TO BRING MVFR FLIGHT CONDITIONS TO PLN/APN...ALTHOUGH STRATUS DECK HAS/IS SLOWLY ERODING. CLOUDS SHOULD SCATTER OUT BY MID TO LATE AFTERNOON AT THOSE SITES LEAVING A PERIOD OF VFR CONDITIONS HEADING INTO THE EVENING. VFR CONDITIONS AT TVC AND MBL WILL PERSIST. TONIGHT...FEAR CYCLE WILL REPEAT AS MARINE STRATUS ONCE AGAIN REDEVELOPS OFF THE LAKE INTO NE LOWER MICHIGAN...LATER THIS EVENING AND FOR THE OVERNIGHT HOURS WITHIN PERSISTENT E/SE FLOW. THUS...HAVE IFR CIGS AND LOW VSBYS ONCE AGAIN TAKING OFF AT APN/PLN THROUGH THE COURSE OF THE NIGHT WHILE TVC/MBL REMAIN LARGELY VFR WITH SOME MINOR REDUCTIONS TO VSBY DUE TO LIGHT FOG. WINDS...LIGHT EASTERLY TODAY...CALM TONIGHT AND LIGHT SE ON SUNDAY. && .MARINE... ISSUED AT 246 AM EDT SAT AUG 23 2014 OVER THE NEXT 48 HOURS, THE WINDS WILL SLOWLY INCREASE AND VEER FROM THE EAST TO THE SOUTH LOW PRESSURE NEAR COLORADO DEEPENS AND MOVES INTO NORTH DAKOTA. SO TODAY THROUGH SUNDAY NIGHT, WILL EXPECT THAT WINDS AND WAVES WILL REMAIN BELOW SMALL CRAFT CONDITIONS. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...ADAM SYNOPSIS...JZ SHORT TERM...JL LONG TERM...JZ AVIATION...ADAM MARINE...JL
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1230 PM CDT SAT AUG 23 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 350 AM CDT SAT AUG 23 2014 WE HAVE BEEN WATCHING AN IMPRESSIVE THUNDERSTORM COMPLEX RACE NORTH ACROSS NEBRASKA OVERNIGHT IN ASSOCIATION WITH A SHORTWAVE ROTATING NNE AROUND THE BASE OF A DEEP TROUGH CENTERED OVER IDAHO. HOWEVER...DO NOT GET TOO EXCITED ABOUT THE PROSPECTS ABOUT ANYONE IN THE MPX CWA SEEING MUCH OF THIS PRECIP TODAY...AS THIS WAA PRECIP LOOKS TO LARGELY GO AROUND THE MPX CWA. MOST CAMS SHOW TWO CONCENTRATED AREAS THIS MORNING HEADING EAST ACROSS IOWA...WITH THE OTHER BATCH OF WIDESPREAD THUNDERSTORMS TO HEAD NORTH ACROSS THE DAKOTAS. THE IOWA AREA IS IN RESPONSE TO AIR GETTING FORCED UP OVER THE REMNANTS OF A COLD FRONT...WHICH AT 3 AM WAS LOCATED JUST SOUTH OF OMAHA TO THE QUAD CITIES...WHICH IS MORE OR LESS THE AXIS WHERE THE HRRR HAS A SWATH OF HIGHER QPF FALLING. THE DAKOTAS BULLSEYE IS RESPONSE THE NOSE OF A 40 KT ESE ORIENTED LLJ THAT WILL BE WORKING NORTH IN CONJUNCTION WITH THE STRONG SHORTWAVE CURRENTLY OVER CENTRAL NEB. WITH THAT SAID...ACTIVITY OUT THERE NOW LOOKS LIKE IT SHOULD HAVE ENOUGH MOMENTUM TO AT LEAST SNEAK UP TO AREAS SOUTH/WEST OF THE MN RIVER. OTHERWISE...FOR MUCH OF THE MPX AREA...THE BAND OF STORMS WE SEE COMING NORTH NOW WILL NOT DO MUCH MORE THAN BRING A BAND OF ALTOCU THROUGH THE AREA. FOR THIS AFTERNOON...ATTENTION TURNS TO THE SEVERE POTENTIAL OUT IN WRN MN. BY THE AFTERNOON...THE BROAD SFC CYCLONE CURRENTLY SPLAYED OUT ACROSS THE CENTRAL HIGH PLAINS WILL HAVE CONSOLIDATED INTO A 1000 MB LOW NEAR THE CENTRAL ND/SD BORDER. THIS WILL HELP PULL THE FRONT IN IOWA BACK NORTH AS A WARM...WITH IT PUSHING INTO SW MN AFTER 00Z. WILL HAVE TO WAIT A WHILE FOR SFC BASED CONVECTION TO FIRE GIVEN EXTENT OF RAIN/CLOUD COVER EXPECTED ACROSS THE DAKOTAS THIS MORNING..BUT EXPECT ENOUGH HEATING TO OCCUR THIS AFTERNOON TO ALLOW FOR STORMS TO DEVELOP NEAR THE SURGING WARM FRONT ALONG THE COTEAU IN SE SODAK AROUND 21Z...AS BOTH THE NMM/ARW SHOW. THIS ACTIVITY SHOULD THEN TRACK NNE...TOWARD WEST CENTRAL AND NORTHWEST MN DURING THE EVENING...AND IT IS THIS POTENTIAL ACTIVITY THAT GIVES US THE SLIGHT RISK FOR TODAY FROM THE SPC. CERTAINLY INSTABILITY AND SHEAR ARE ADEQUATE TO SUPPORT SURFACE BASED SUPERCELLS AND THEREFOR ALL MODES OF SEVERE WEATHER. HOWEVER...FOR AS FAR EAST AS MN...SHEAR VECTORS WILL BE MORE PARALLEL THAN PERPENDICULAR TO THE FORCING...WHICH WOULD FAVOR THE CONGEALING OF ACTIVITY INTO CLUSTERS/LINES...WHICH IS WHAT IS SEEN WITH NMM/ARW REFLECTIVITY FORECASTS. THIS WOULD FAVOR THE HIGHEST TORNADO THREAT BEING ACROSS THE DAKOTAS...WHERE STORMS ARE MORE LIKELY TO BE DISCRETE...WITH WRN MN DEALING MORE WITH A POTENTIAL WIND/HAIL THREAT. FROM THE FLOOD TREAT...PWATS WILL INCREASE BACK TO AROUND 1.75 INCHES...SO CERTAINLY WILL SEE HEAVY RAIN WITH THIS ACTIVITY. HOWEVER...CURRENT EXPECTATIONS ARE THAT ACTIVITY WILL BE PROGRESSIVE ENOUGH TO KEEP ANY CONCENTRATED SWATHS OF HIGH QPF DOWN IN THE 1-2 INCH RANGE AS OPPOSED TO BEING UP IN THE 3-6 INCH RANGE LIKE WE WERE SEEING LAST WEEK. FOR TONIGHT...BEST UPPER FORCING WILL BE STAYING NW OF THE MPX CWA...SO ACTIVITY THAT MOVES INTO WRN MN WILL HEAD FOR NW/NC MN...SO CUT BACK CONSIDERABLY ON POPS...KEEPING THE ERN 2/3RDS OR SO OF THE CWA DRY. MAY STILL BE TOO FAR EAST WITH POPS TONIGHT...BUT WE SHOULD SEE SOMEWHAT OF AN EWRD PUSH WITH ACTIVITY TONIGHT AS COLD POOLS GET GENERATED. EVEN IF IT DOES NOT RAIN...IT WILL BE A MUGGY NIGHT...AS LOWER 70 DEWPS COME UP WITH THE WARM FRONT. WILL LIKELY MAKE IT TOUGH FOR MUCH OF THE MN CWA TO DIP BELOW 70 SUNDAY MORNING...WHICH WILL HAVE IMPLICATIONS ON THE POTENTIAL NEED FOR ANY HEAT HEADLINES SUNDAY. NOT WORRIED ABOUT FOG TONIGHT EITHER...AS GRADIENT WILL REMAIN STRONG THROUGH THE NIGHT...SO WILL BE ANOTHER NIGHT LIKE TONIGHT WHERE WE JUST WATCH ANY STRATUS THAT SURVIVES THE DAY TODAY EXPAND AGAIN OVERNIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 350 AM CDT SAT AUG 23 2014 THERE IS DEFINITELY SOME SPREAD IN THE MODEL GUIDANCE AS WE HEAD THROUGH THE LATTER PORTION OF THE FORECAST... BUT THE GENERAL SCENARIO SUGGESTS A TRANSITION FOR WESTERN RIDGE/EASTERN TROUGH TO MORE OF A ZONAL PATTERN BY THE END OF THE WEEK. THIS SHOULD ALLOW FOR TEMPERATURES TO TREND FROM ABOVE NORMAL TO NEAR NORMAL AS THE WEEK UNFOLDS... WITH PCPN CHANCES BEING A BIT TOUGH TO PIN DOWN DEPENDING UPON WHERE THE MAIN BAROCLINIC ZONE SETS UP. GIVEN THE SPREAD IN DETERMINISTIC AND ENSEMBLE GUIDANCE... A CONSENSUS APPROACH IS THE MOST SENSIBLE COURSE OF ACTION... SO STUCK CLOSE TO A MULTI-MODEL BLEND. THE MAIN FORECAST ISSUES LOOK TO BE THE POTENTIAL FOR EXCESSIVE HEAT/HUMIDITY SUNDAY... THEN THE POSSIBILITY OF SIGNIFICANT PCPN OVER THE SOUTHERN PORTION OF THE AREA LATE MONDAY THROUGH WEDNESDAY AS THE FRONTAL BOUNDARY HANGS UP SOMEWHERE NEAR THE MINNESOTA/IOWA BORDER. SUNDAY STILL LOOKS TO HAVE THE POTENTIAL FOR VERY WARM TEMPERATURES ACROSS THE AREA... ALONG WITH HIGH DEWPOINTS. AT THIS POINT... APPARENT TEMPERATURE FORECASTS PEAK AROUND 100 OVER A PORTION OF THE AREA SUNDAY AFTERNOON WITH FORECAST HIGHS IN THE LOW 90S AND DEWPOINTS NEAR 70. WET BULB GLOBE TEMPERATURES JUMP INTO THE LOWER TO MIDDLE 80S AS WELL... ALSO INDICATING THE POTENTIAL FOR HEAT RELATED ISSUES FOR PEOPLE WHO MAY BE OUTDOORS ON SUNDAY. THERE WILL CERTAINLY BE A SIGNIFICANT NUMBER OF PEOPLE OUTDOORS IN THE METRO AREA ON SUNDAY WITH THE GREAT MINNESOTA GET TOGETHER IN FULL SWING... SO THE POSSIBILITY OF EXCESSIVE HEAT/HUMIDITY WILL NEED TO BE MONITORED IN SUBSEQUENT FORECASTS. AT THIS POINT... THERE IS STILL SOME UNCERTAINTY IN CLOUD COVER AND WHETHER WE/LL MIX AS WELL AS SOME GUIDANCE SUGGESTS AND/OR SEE MORE LOW LEVEL EVAPORATIVE COOLING THAN ANTICIPATED. SO... WILL HIGHLIGHT THE POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK AND OTHER SERVICES... BUT HOLD OFF ON ANY ACTUAL HEADLINES AT THIS POINT. PCPN CHANCES ON SUNDAY LOOK TO BE CONFINED TO THE WESTERN/NORTHERN PORTION OF THE AREA UNTIL LATE AFTERNOON AND/OR EVENING WHEN THE COLD FRONT FINALLY STARTS TO WORK ITS WAY EAST ACROSS THE AREA. AT THAT POINT... THE MAIN LARGE SCALE FORCING WILL BE TO OUR NORTH... SO PCPN MAY BE SCATTERED IN NATURE WITH MORE WIDESPREAD ACTIVITY WITH THE SHORTWAVE AND TRIPLE-POINT TO OUR NORTH AND THE SECONDARY WARM ADVECTION/INSTABILITY NOSE TO OUR SOUTH. DEEP LAYER SHEAR WILL BE BEST TO OUR NORTH... SO ANY SEVERE POTENTIAL LOOKS TO BE CAPE- DRIVEN WITH MAINLY MULTI-CELL WIND/HAIL STORMS BEING THE CONCERN. CHANCES FOR PCPN WILL PUSH EAST SUNDAY NIGHT WITH THE FRONT... THEN WE/LL SEE HIGH PRESSURE BUILD OVER MUCH OF THE AREA. HOWEVER... THE FRONTAL BOUNDARY LOOKS TO HANG UP TO OUR SOUTH/EAST MONDAY INTO WEDNESDAY... NECESSITATING THE INCLUSION OF POPS OVER MUCH OF THE AREA DURING THAT TIME FRAME... WITH BETTER CHANCES SOUTH AND LOW CHANCES NORTH. THE FAR SOUTHERN PORTION OF THE AREA HAS SOME POTENTIAL TO SEE SIGNIFICANT RAINFALL OVER THAT PERIOD OF TIME... BUT MUCH WILL DEPEND ON WHERE SUCCESSIVE ROUNDS OF SHRA/TSRA DECIDE TO TRACK... AND IT IS TOO EARLY TO GET A GOOD HANDLE ON THAT EVOLUTION. WE SHOULD SEE HIGH PRESSURE... SUBSIDENCE... AND DRIER AIR WORK INTO THE ENTIRE AREA FROM THE NORTHWEST WEDNESDAY NIGHT THROUGH THE REMAINDER OF THE FORECAST PERIOD... WITH DRY WEATHER PREDOMINATING. HOWEVER... THE 00Z ECMWF IS A BIT SLOWER IN SHOWING THIS EVOLUTION IN COMPARISON TO ITS PREVIOUS RUNS OR THE 00Z GFS... SO WE/LL NEED TO SEE HOW THINGS EVOLVE IN SUBSEQUENT FORECASTS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1212 PM CDT SAT AUG 23 2014 NORTHERN EDGE OF DISSIPATING MCS OVER EASTERN IOWA CLIPPED KMSP AROUND NOON. LIGHT -SHRA INDICATED. THIS CONTINUES TO MOVE EAST AND IF MAY AFFECT KEAU EARLY. INCLUDED VCSH FOR THAT. COMPLICATED SCENARIO DEVELOPING WITH THE UPPER TROUGH MOVING THROUGH THE DAKOTAS. HIRES MODELS ARE PICKING UP ON SOME ACCAS LIFITNG OUT OF SOUTHEAST SODAK. THEY DEVELOP SOME ISOLD TSRA INTO SW MN DURING THE AFTERNOON...AND DISSIPATE LATE AFTERNOON INTO SC MN. WONT MENTION THIS ACTIVITY AT TAF SITE FOR NOW. LOWER IFR CLOUDS REMAIN LOCKED OVER CENTRAL MN WITH SOME EROSION NOTED INTO SC MN. THIS MAY WORK N-NE INTO THE AFTERNOON IN THE WAKE OF THE IOWA MCS. WILL TREND VFR THROUGH ABOUT 00Z MOST AREAS. EXPECT THUNDER TO DEVELOP AROUND 00Z IN EASTERN SODAK AND LIT NORTHEAST OVER WESTERN AND CENTRAL MN THROUGH THE NIGHT. HEAVY RAIN/POSSIBLE SEVERE INTO FAR WESTERN MN THROUGH ABOUT 06Z OR SO. WILL DROP CIGS AGAIN TO IFR OVERNIGHT AS WARM FRONT LIFTS OVER THE AREA. WILL MENTION MAINLY 3-5SM BR WITH IFR CIGS. EXPECT SLOW IMPROVEMENT AGAIN INTO SATURDAY MORNING...SIMILAR TO PREVIOUS FORECAST TREND. INCREASING GRADIENT AHEAD OF FRONT SHOULD YIELD SOME STRONG SE-S SOUTH WINDS WITH FROPA SATURDAY. KMSP...-SHRA/SPINKLES EXITING KMSP NOW. NEXT THREAT MOVES IN AFTER 05Z WITH A PROB30 FOR THUNDER INDICATED THROUGH 08Z. CIGS EXPECTED TO DROP OFF TO IFR LATE WITH IMPROVING CONDITIONS TO MVFR BY MIDE/LATE SUNDAY MORNING. EAST TO SOUTHEAST WINDS AHEAD OF WARM FRONT...WITH WINDS BECOMING MORE SOUTHERLY BY LATE SUNDAY MORNING OR EARLY SUNDAY AFTERNOON. SPEEDS AREA EXPECTED TO REMAIN AROUND 10KTS INTO TONIGHT...INCREASING TO 10-14KTS SUNDAY MORNING. /OUTLOOK FOR KMSP/ SUN NIGHT...VFR. CHANCE MVFR/TSRA. S WINDS 10-14KTS BCMG W 5-10 KTS. MON...VFR. WINDS W 5-10 KTS. TUE...SHRA/TSRA AND MVFR LIKELY BY AFTERNOON. WINDS NE 5-10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM... AVIATION...DWE
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
553 PM CDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 313 PM CDT SAT AUG 23 2014 H5 ANALYSIS FROM THIS MORNING HAS RIDGING ACROSS THE MISSISSIPPI VALLEY FROM THE GULF COAST NWD INTO THE WESTERN GREAT LAKES. FURTHER EAST...DECENT SHORTWAVES WERE NOTED OVER LAKE ONTARIO AND NOVA SCOTIA. FURTHER WEST...A TANDEM OF SHORTWAVES WERE LOCATED OVER THE INTERMOUNTAIN WEST. THE FIRST OVER WESTERN COLORADO AND A SECOND OVER EASTERN IDAHO...WHILE ANOTHER SHORTWAVE WAS UPSTREAM OVER THE ALASKA PANHANDLE. WV IMAGERY AS OF 1 PM CDT...INDICATED SHORTWAVE ENERGY IN ASSOCIATION WITH THE WAVE OVER WESTERN COLORADO HAD BEGUN TO EMERGE ACROSS CENTRAL COLORADO AND HAS LED TO INCREASING CLOUDINESS ALONG THE FRONT RANGE OF COLORADO. OVER THE NEXT COUPLE OF HRS...SHRAS AND TSRAS ARE EXPECTED TO DEVELOP ON THE LEE SIDE OF THE ROCKIES INVOF THE FRONT RANGES OF COLORADO AND WYOMING. FURTHER WEST...A CLOSED LOW REMAINS IN PLACE OVER EASTERN IDAHO ATTM WITH A BROAD AREA OF CLOUDS AND SHOWERS ACROSS MONTANA...NORTH DAKOTA AND NORTHERN SOUTH DAKOTA. ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...ABUNDANT CLOUDINESS WAS PRESENT OVER MOST OF THE AREA WITH THE EXCEPTION OF FAR SWRN NEBRASKA AND THE EASTERN NEBRASKA PANHANDLE WHERE CLOUDS HAVE SCATTERED OUT OVER THE PAST 1 TO 2 HOURS. AT THE SURFACE...A TANDEM OF LOW PRESSURE CENTERS WERE PRESENT ACROSS SERN WYOMING AND A SECOND OVER SOUTH CENTRAL SD. A WARM FRONT EXTENDED FROM SERN WYOMING INTO EASTERN SOUTH DAKOTA...WHILE A COLD FRONT EXTENDED SSWD INTO THE CENTRAL ROCKIES. UNDER PARTLY TO MOSTLY CLOUDY SKIES...TEMPERATURES AS OF 3 PM CDT...RANGED FROM 72 AT AINSWORTH...TO 82 AT BROKEN BOW. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 313 PM CDT SAT AUG 23 2014 MODELS REMAIN IN GOOD AGREEMENT WITH THE PROJECTIONS OF A PV ANOMALY LIFTING NORTHEAST FROM FAR SOUTHWESTERN WYOMING TOWARD THE NORTHERN PLAINS THIS EVENING AND OVERNIGHT. RECENT OBSERVATIONS INDICATE THAT THE LOW STRATUS IS DISSIPATING EARLY THIS AFTERNOON...LEADING TO THE EVENTUAL DESTABILIZATION OF THE LOWER TROPOSPHERE. AS HEIGHTS FALL WITH THE APPROACH OF THE PV MAX/ATTENDANT COLD FRONT...STORMS ARE ANTICIPATED TO FORM INVOF OF THE HIGH PLAINS SURFACE LOW/FRONTAL BOUNDARY AND POSSIBLY DRIFT EAST ACROSS THE SANDHILLS REGION OF NEB OVERNIGHT. THE LATEST PROJECTIONS FROM THE RAP AND HRRR SHOWS THAT DESPITE THE MORNING CLOUDS...LOW TO MID LEVEL LAPSE RATES HAVE INCREASED SOME...YIELDING A WEAKLY UNSTABLE ATMOSPHERE ACROSS WESTERN PORTIONS OF THE CWA /CONTINUED CLEARING WILL ALLOW FOR FURTHER DESTABILIZATION/. THE PROJECTED INSTABILITY /UPWARDS TO 1000 J/KG ML CAPE/ COMBINED WITH 0-6KM BULK SHEAR OF 30KTS OR SO WILL PROMOTE THE POSSIBILITY OF STRONG TO LOW END SEVERE STORMS THIS EVENING AND OVERNIGHT. ANOTHER AREA TO WATCH FOR SEVERE STORMS WILL BE ACROSS NORTH CENTRAL NEBRASKA LATE THIS AFTERNOON AS A SECONDARY WARM FRONT LIFTS NORTH TOWARD THE SOUTHEAST SOUTH DAKOTA. ABUNDANT INSTABILITY AND SUFFICIENT SHEAR WOULD PROMOTE RAPID STORM DEVELOPMENT CAPABLE OF LARGE HAIL AND DAMAGING WIND GUSTS. THE HEAVY RAIN THREAT WILL BE NOTICEABLY LESS TONIGHT AS BUFR SOUNDINGS REVEAL A MUCH LESSER INFLUENCE FROM WARM RAIN PROCESSES...BUT WITH PWATS AT OR SLIGHTLY ABOVE AVERAGE...BRIEF HEAVY RAINFALL IS STILL POSSIBLE. THE COLD FRONT CLEARS THE CWA EARLY ON SUNDAY WITH RAIN CHANCES POSSIBLY LINGERING ACROSS OUR FAR EAST THROUGH 15Z...OTHERWISE A SLIGHTLY COOLER AIRMASS IS ANTICIPATED WITH HIGHS RANGING FROM THE MID 70S ACROSS OUR FAR NORTHWEST...TO LOW TO MID 80S SOUTH OF THE INTERSTATE 80 CORRIDOR. WITH MOISTURE LACKING AND A STABLE AIRMASS ANTICIPATED SUNDAY AFTERNOON...STORM CHANCES SHOULD BE KEPT AT BAY UNTIL AT LEAST 00Z MONDAY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 331 PM CDT SAT AUG 23 2014 SUNDAY NIGHT THROUGH TUESDAY...THE MAIN FORECASTING CHALLENGE CONTINUES TO BE PRECIPITATION CHANCES AND THE THREAT FOR HEAVY RAIN AS A TROUGH AND SEMI STATIONARY FRONTAL BOUNDARY PERSISTS ACROSS THE CENTRAL ROCKIES AND PLAINS DURING THE PERIOD. FOR SUNDAY NIGHT...AFTER RELATIVELY QUIET WEATHER CONDS SUNDAY...MID LEVEL WAA WILL INCREASE ALONG THE FRONT RANGE DURING THE EVENING...TRANSITIONING EAST ACROSS THE CENTRAL PLAINS OVERNIGHT SUNDAY NIGHT INTO EARLY MONDAY. AT THE SAME TIME...A NICE H250 JET STREAK WILL LIFT ACROSS NWRN NEBRASKA INTO SOUTH DAKOTA PLACING WESTERN AND NORTH CENTRAL NEBRASKA IN THE RIGHT REAR QUAD OF THIS FEATURE. ENHANCED LIFT ACROSS THE FORECAST AREA...WILL LEAD TO A SHARP INCREASE IN THE THREAT OF PCPN SUNDAY NIGHT INTO MONDAY. IN THE LOWER LEVELS...A FRONTAL BOUNDARY WILL BE ANCHORED ACROSS SRN NEBRASKA SUNDAY NIGHT WITH THE NOSE OF A H85 LOW LEVEL JET POSITIONED ACROSS SWRN NEBRASKA. INHERITED FCST HAD THE HIGHEST POPS ACROSS SRN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT INTO MONDAY MORNING AND APPEARS ON TRACK ATTM. PRECIPITATION CHANCES WILL DECREASE SOMEWHAT MONDAY AS MID LEVEL FORCING PUSHES EAST INTO THE MID MISSOURI VALLEY. BY MONDAY NIGHT...ANOTHER STRONG UPPER LEVEL DISTURBANCE WILL PUSH ACROSS THE CENTRAL PLAINS...LEADING TO INCREASED CHANCES FOR RAIN MONDAY NIGHT...AS WELL AS TUESDAY NIGHT. LOW LEVEL EASTERLY WINDS AND ABUNDANT MID AND UPPER LEVEL MOISTURE TRANSPORT FROM THE SOUTHWEST IN ASSOCIATION WITH HURRICANE MARIE COULD LEAD TO HEAVY RAIN ACROSS THE CENTRAL PLAINS BEGINNING MONDAY NIGHT AND POSSIBLY PERSISTING INTO TUESDAY NIGHT. FURTHER SUPPORT FOR HEAVY RAIN IS EVIDENT IN FCST PWATS RANGING FROM 1.5 TO 2.0 INCHES MONDAY NIGHT THROUGH TUESDAY NIGHT. WEDNESDAY THROUGH SATURDAY...LINGERING PCPN CHANCES ARE THE MAIN FORECAST CHALLENGE IN THE LONG RANGE PERIODS. BY WEDNESDAY INTO THURSDAY...THE PERSISTENT UPPER LEVEL TROUGH ACROSS THE ROCKIES...WILL CROSS THE CENTRAL PLAINS INTO THE MISSISSIPPI VALLEY. THE LATEST GFS SOLN IS 24 HRS FASTER COMPARED TO THE ECMWF IN LIFTING THIS FEATURE EAST OF THE AREA. THE GFS IS DRY AFTER WEDS WITH THE TROUGH OVER MISSOURI VALLEY BY 12Z THURSDAY...WHILE THE ECMWF HAS THIS FEATURE OVER THE SAME AREA BY 12Z FRIDAY. INHERITED FCST WAS DRY WEDS NIGHT AND INTRODUCED POPS FOR THIS PERIOD AS BOTH MODELS HAVE TRENDED SLOWER. WILL HOLD OFF ON INTRODUCING POPS FOR THURSDAY FOR NOW AND WAIT FOR THE MODELS TO COME INTO BETTER AGREEMENT. AFTER UNSEASONABLY COOL HIGHS IN THE 70S FOR WEDNESDAY AND THURSDAY...HIGHS WILL REBOUND BACK INTO THE 80S FOR THURSDAY AND FRIDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 553 PM CDT SAT AUG 23 2014 A PACIFIC COLD FRONT IS ENTERING WRN NEB THIS EVENING. THE FRONT IS EXPECTED TO BE THE FOCUS FOR CONTINUED TSTM DEVELOPMENT OVERNIGHT. STORM ACTIVITY IS EXPECTED TO DIMINISH IN COVERAGE ACROSS NCNTL NEB BY 12Z SUNDAY AND VFR IS EXPECTED THEREAFTER ALL AREAS. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CLB SHORT TERM...JACOBS LONG TERM...CLB AVIATION...CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
359 PM CDT SAT AUG 23 2014 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 345 PM CDT SAT AUG 23 2014 STUBBORN LOWER CLOUDS STILL HANGING ON ACROSS NORTHWEST PART OF THE FORECAST AREA. SULTRY AIRMASS TODAY AS WELL...WITH DEWPOINTS AROUND 70 SEVERAL LOCATIONS. MOST MODELS TRY TO PUMP IN SOME DRIER AIR FROM THE SOUTH THROUGH THIS EVENING...WITH THE HRRR MOST AGGRESSIVE. THAT COULD PROVIDE A LITTLE HUMIDITY RELIEF TO SOME SPOTS IN THE SOUTHERN/SOUTHEAST FORECAST AREA. AS WE WORK INTO TONIGHT...THE PROSPECT OF THUNDERSTORMS IS MUCH MUCH LOWER...BUT NOT NIL. A DECENT LOW LEVEL JET WILL DEVELOP AND THAT COULD SUSTAIN HIGH PLAINS CONVECTION...BUT ALSO SPARK A FEW OTHER ISOLATED SHOWERS AND STORMS. OVERALL COVERAGE SHOULD BE ISOLATED...BUT CAN NOT TOTALLY RULE IT OUT. SUNDAY SHOULD START WITH LINGERING MID/HIGH CLOUDS FROM LEFTOVER SHOWERS AND THUNDERSTORMS IN PARTS OF THE PLAINS. THESE MAY HOLD OVER INTO THE POST SUNRISE HOURS OVER NORTHERN PARTS OF THE FORECAST NEAR A FRONTAL BOUNDARY...BUT COVERAGE WILL BE SPARSE AND 20 PERCENT CHANCES REPRESENT RAIN RISK WELL. A WEAK FRONTAL BOUNDARY WILL ATTEMPT TO MOVE ACROSS THE FORECAST AREA SUNDAY. MODELS SEEM A BIT AGGRESSIVE...BUT SOMETIMES THAT DOES WORK OUT. EXPECT A SHIFTING WIND...AND THEN A DYING WIND AS THE FORECAST IS LEFT TO FLOUNDER IN THE SURFACE SURFACE WITH THE FRONT WEAKENING WITH TIME. THE WEAK NATURE OF THE FRONT AND SOME WARM MID LEVEL TEMPERATURES WILL PROBABLY KEEP ANY DEVELOPMENT OF THUNDERSTORMS NEAR OR ALONG THE FRONT VERY SPARSE AND TOWARD EVENING AT THE EARLIEST. HAVE KEPT SIMILAR IDEA OF LOWER DEWPOINTS BEHIND THE FRONTAL PASSAGE...BUT HAVE SOME DOUBT PLACES LIKE GRAND ISLAND AND HASTINGS COULD DROP TO A SUB-60 DEWPOINT LATE SUNDAY AFTERNOON. THAT WOULD BE NICE BUT WE WILL SEE. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 345 PM CDT SAT AUG 23 2014 UNSETTLED WEATHER CONDITIONS WILL CONTINUE THROUGH MUCH OF THE EXTENDED PERIODS AS THE LOCAL AREA WILL REMAIN UNDER THE INFLUENCE OF A LARGE TROUGH OF LOW PRESSURE ACROSS THE INTERMOUNTAIN WEST WITH WEST TO SOUTHWESTERLY FLOW PERSISTING ALOFT. EXPECT THE MAIN UPPER LEVEL LOW ACROSS THE DAKOTAS SUNDAY EVENING TO LIFT NORTHEAST...WITH A SECONDARY FRONTAL BOUNDARY PUSHING ACROSS THE LOCAL AREA. WHILE THIS FRONTAL BOUNDARY MAY PROVIDE THE TRIGGER FOR SOME ELEVATED CONVECTION ACROSS THE SOUTHEASTERN PORTIONS OF THE LOCAL AREA EARLY IN THE EVENING...EXPECT THE BETTER CHANCES TO SPREAD FROM WEST TO EAST AFTER MIDNIGHT AS A TRAILING MID LEVEL DISTURBANCE MOVES ACROSS THE LOCAL AREA FROM THE HIGH PLAINS AND A WEAK LOW LEVEL JET FOCUSES ITSELF ACROSS NORTH CENTRAL KANSAS. AS THIS FIRST UPPER LEVEL LOW TRACKS WELL INTO CANADA...EXPECT A SECOND UPPER LEVEL LOW TO SLIDE FROM THE PACIFIC NORTHWEST AND INTO THE INTERMOUNTAIN WEST BY MONDAY...MAINTAINING SOUTHWESTERLY ALOFT ACROSS THE REGION. WHILE CHANCES FOR PRECIPITATION WILL DECREASE SOME DURING THE DAY ON MONDAY...KEPT SOME SMALL POPS IN THE FORECAST AS THE OLD FRONTAL BOUNDARY WILL BE MEANDERING ACROSS THE REGION. THAT SAID...THE BETTER SHOT FOR MORE WIDESPREAD CONVECTION WILL BE MONDAY NIGHT...AS YET ANOTHER UPPER LEVEL DISTURBANCE IN SOUTHWESTERLY FLOW TRAVERSES THE REGION IN CONCERT WITH AN INCREASING LOW LEVEL JET AIMED ACROSS SOUTH CENTRAL NEBRASKA. WITH SEVERAL THOUSAND JOULES OF CAPE IN PLACE AND MODEST SHEAR VALUES FORECAST...EXPECT THE POTENTIAL FOR AN ACTIVE NIGHT ACROSS THE LOCAL AREA...ESPECIALLY FROM THE STATE LINE NORTH. DUE TO SOME DISCREPANCIES IN MODEL DATA... HOWEVER...ONLY WENT AHEAD AND ADVERTISED LIMITED SEVERE POTENTIAL FOR MONDAY NIGHT IN THE HWO. OTHERWISE...THUNDERSTORM ACTIVITY TUESDAY SHOULD ONCE AGAIN BE FOCUSED NEAR THE LOW LEVEL JET DURING THE EVENING AND OVERNIGHT HOURS...WITH A COLD FRONT EXPECTED TO BRING YET ANOTHER CHANCE FOR THUNDERSTORMS ACROSS THE LOCAL AREA WEDNESDAY AND WEDNESDAY NIGHT. WHILE A CHANCE FOR PRECIPITATION IS IN THE FORECAST SUNDAY THROUGH THURSDAY...AT THIS TIME THE BEST POTENTIAL FOR ANY SEVERE WEATHER APPEARS TO BE PRIMARILY DURING THE EVENING AND OVERNIGHT HOURS MONDAY THROUGH WEDNESDAY...WITH A COOLER...DRIER...AND MORE STABLE AIRMASS EXPECTED TO SETTLE IN ACROSS THE REGION TO END THE WEEK. HYDROLOGY WISE...DUE TO THE RECENT RAINFALL AND SATURATED SOILS ACROSS MUCH OF THE LOCAL AREA...CONTINUED WITH THE MENTION OF LOCALIZED FLOODING THE HWO IN THIS UNSETTLED PATTERN. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1235 PM CDT SAT AUG 23 2014 SLOWLY ERODING LOW CLOUDS OUT OF SOUTH CENTRAL NEBRASKA. GRAND ISLAND PRETTY MUCH IN THE CLEAR IT APPEARS...WHILE KEARNEY MAY SKIRT WITH SOME SCATTERED AFTERNOON CLOUDS BUT OVERALL TREND SHOULD BE CLEARING OUT. WINDS WILL CONTINUE TO INCREASE AHEAD OF DEEPENING LOW LEVEL TROUGH WITH GUSTS OVER 20 MPH NOT UNCOMMON. PRECIPITATION WHICH DEVELOPS TO THE WEST TONIGHT COULD MOVE INTO THE AREA LATE IN THE FORECAST...BUT WAS NOT CONFIDENT IN ITS COVERAGE TO ADD TO FORECAST AT THIS TIME. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...MORITZ LONG TERM...ROSSI AVIATION...NOAA/NWS/MORITZ
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
313 PM CDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 313 PM CDT SAT AUG 23 2014 H5 ANALYSIS FROM THIS MORNING HAS RIDGING ACROSS THE MISSISSIPPI VALLEY FROM THE GULF COAST NWD INTO THE WESTERN GREAT LAKES. FURTHER EAST...DECENT SHORTWAVES WERE NOTED OVER LAKE ONTARIO AND NOVA SCOTIA. FURTHER WEST...A TANDEM OF SHORTWAVES WERE LOCATED OVER THE INTERMOUNTAIN WEST. THE FIRST OVER WESTERN COLORADO AND A SECOND OVER EASTERN IDAHO...WHILE ANOTHER SHORTWAVE WAS UPSTREAM OVER THE ALASKA PANHANDLE. WV IMAGERY AS OF 1 PM CDT...INDICATED SHORTWAVE ENERGY IN ASSOCIATION WITH THE WAVE OVER WESTERN COLORADO HAD BEGUN TO EMERGE ACROSS CENTRAL COLORADO AND HAS LED TO INCREASING CLOUDINESS ALONG THE FRONT RANGE OF COLORADO. OVER THE NEXT COUPLE OF HRS...SHRAS AND TSRAS ARE EXPECTED TO DEVELOP ON THE LEE SIDE OF THE ROCKIES INVOF THE FRONT RANGES OF COLORADO AND WYOMING. FURTHER WEST...A CLOSED LOW REMAINS IN PLACE OVER EASTERN IDAHO ATTM WITH A BROAD AREA OF CLOUDS AND SHOWERS ACROSS MONTANA...NORTH DAKOTA AND NORTHERN SOUTH DAKOTA. ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...ABUNDANT CLOUDINESS WAS PRESENT OVER MOST OF THE AREA WITH THE EXCEPTION OF FAR SWRN NEBRASKA AND THE EASTERN NEBRASKA PANHANDLE WHERE CLOUDS HAVE SCATTERED OUT OVER THE PAST 1 TO 2 HOURS. AT THE SURFACE...A TANDEM OF LOW PRESSURE CENTERS WERE PRESENT ACROSS SERN WYOMING AND A SECOND OVER SOUTH CENTRAL SD. A WARM FRONT EXTENDED FROM SERN WYOMING INTO EASTERN SOUTH DAKOTA...WHILE A COLD FRONT EXTENDED SSWD INTO THE CENTRAL ROCKIES. UNDER PARTLY TO MOSTLY CLOUDY SKIES...TEMPERATURES AS OF 3 PM CDT...RANGED FROM 72 AT AINSWORTH...TO 82 AT BROKEN BOW. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 313 PM CDT SAT AUG 23 2014 MODELS REMAIN IN GOOD AGREEMENT WITH THE PROJECTIONS OF A PV ANOMALY LIFTING NORTHEAST FROM FAR SOUTHWESTERN WYOMING TOWARD THE NORTHERN PLAINS THIS EVENING AND OVERNIGHT. RECENT OBSERVATIONS INDICATE THAT THE LOW STRATUS IS DISSIPATING EARLY THIS AFTERNOON...LEADING TO THE EVENTUAL DESTABILIZATION OF THE LOWER TROPOSPHERE. AS HEIGHTS FALL WITH THE APPROACH OF THE PV MAX/ATTENDANT COLD FRONT...STORMS ARE ANTICIPATED TO FORM INVOF OF THE HIGH PLAINS SURFACE LOW/FRONTAL BOUNDARY AND POSSIBLY DRIFT EAST ACROSS THE SANDHILLS REGION OF NEB OVERNIGHT. THE LATEST PROJECTIONS FROM THE RAP AND HRRR SHOWS THAT DESPITE THE MORNING CLOUDS...LOW TO MID LEVEL LAPSE RATES HAVE INCREASED SOME...YIELDING A WEAKLY UNSTABLE ATMOSPHERE ACROSS WESTERN PORTIONS OF THE CWA /CONTINUED CLEARING WILL ALLOW FOR FURTHER DESTABILIZATION/. THE PROJECTED INSTABILITY /UPWARDS TO 1000 J/KG ML CAPE/ COMBINED WITH 0-6KM BULK SHEAR OF 30KTS OR SO WILL PROMOTE THE POSSIBILITY OF STRONG TO LOW END SEVERE STORMS THIS EVENING AND OVERNIGHT. ANOTHER AREA TO WATCH FOR SEVERE STORMS WILL BE ACROSS NORTH CENTRAL NEBRASKA LATE THIS AFTERNOON AS A SECONDARY WARM FRONT LIFTS NORTH TOWARD THE SOUTHEAST SOUTH DAKOTA. ABUNDANT INSTABILITY AND SUFFICIENT SHEAR WOULD PROMOTE RAPID STORM DEVELOPMENT CAPABLE OF LARGE HAIL AND DAMAGING WIND GUSTS. THE HEAVY RAIN THREAT WILL BE NOTICEABLY LESS TONIGHT AS BUFR SOUNDINGS REVEAL A MUCH LESSER INFLUENCE FROM WARM RAIN PROCESSES...BUT WITH PWATS AT OR SLIGHTLY ABOVE AVERAGE...BRIEF HEAVY RAINFALL IS STILL POSSIBLE. THE COLD FRONT CLEARS THE CWA EARLY ON SUNDAY WITH RAIN CHANCES POSSIBLY LINGERING ACROSS OUR FAR EAST THROUGH 15Z...OTHERWISE A SLIGHTLY COOLER AIRMASS IS ANTICIPATED WITH HIGHS RANGING FROM THE MID 70S ACROSS OUR FAR NORTHWEST...TO LOW TO MID 80S SOUTH OF THE INTERSTATE 80 CORRIDOR. WITH MOISTURE LACKING AND A STABLE AIRMASS ANTICIPATED SUNDAY AFTERNOON...STORM CHANCES SHOULD BE KEPT AT BAY UNTIL AT LEAST 00Z MONDAY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 331 PM CDT SAT AUG 23 2014 SUNDAY NIGHT THROUGH TUESDAY...THE MAIN FORECASTING CHALLENGE CONTINUES TO BE PRECIPITATION CHANCES AND THE THREAT FOR HEAVY RAIN AS A TROUGH AND SEMI STATIONARY FRONTAL BOUNDARY PERSISTS ACROSS THE CENTRAL ROCKIES AND PLAINS DURING THE PERIOD. FOR SUNDAY NIGHT...AFTER RELATIVELY QUIET WEATHER CONDS SUNDAY...MID LEVEL WAA WILL INCREASE ALONG THE FRONT RANGE DURING THE EVENING...TRANSITIONING EAST ACROSS THE CENTRAL PLAINS OVERNIGHT SUNDAY NIGHT INTO EARLY MONDAY. AT THE SAME TIME...A NICE H250 JET STREAK WILL LIFT ACROSS NWRN NEBRASKA INTO SOUTH DAKOTA PLACING WESTERN AND NORTH CENTRAL NEBRASKA IN THE RIGHT REAR QUAD OF THIS FEATURE. ENHANCED LIFT ACROSS THE FORECAST AREA...WILL LEAD TO A SHARP INCREASE IN THE THREAT OF PCPN SUNDAY NIGHT INTO MONDAY. IN THE LOWER LEVELS...A FRONTAL BOUNDARY WILL BE ANCHORED ACROSS SRN NEBRASKA SUNDAY NIGHT WITH THE NOSE OF A H85 LOW LEVEL JET POSITIONED ACROSS SWRN NEBRASKA. INHERITED FCST HAD THE HIGHEST POPS ACROSS SRN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT INTO MONDAY MORNING AND APPEARS ON TRACK ATTM. PRECIPITATION CHANCES WILL DECREASE SOMEWHAT MONDAY AS MID LEVEL FORCING PUSHES EAST INTO THE MID MISSOURI VALLEY. BY MONDAY NIGHT...ANOTHER STRONG UPPER LEVEL DISTURBANCE WILL PUSH ACROSS THE CENTRAL PLAINS...LEADING TO INCREASED CHANCES FOR RAIN MONDAY NIGHT...AS WELL AS TUESDAY NIGHT. LOW LEVEL EASTERLY WINDS AND ABUNDANT MID AND UPPER LEVEL MOISTURE TRANSPORT FROM THE SOUTHWEST IN ASSOCIATION WITH HURRICANE MARIE COULD LEAD TO HEAVY RAIN ACROSS THE CENTRAL PLAINS BEGINNING MONDAY NIGHT AND POSSIBLY PERSISTING INTO TUESDAY NIGHT. FURTHER SUPPORT FOR HEAVY RAIN IS EVIDENT IN FCST PWATS RANGING FROM 1.5 TO 2.0 INCHES MONDAY NIGHT THROUGH TUESDAY NIGHT. WEDNESDAY THROUGH SATURDAY...LINGERING PCPN CHANCES ARE THE MAIN FORECAST CHALLENGE IN THE LONG RANGE PERIODS. BY WEDNESDAY INTO THURSDAY...THE PERSISTENT UPPER LEVEL TROUGH ACROSS THE ROCKIES...WILL CROSS THE CENTRAL PLAINS INTO THE MISSISSIPPI VALLEY. THE LATEST GFS SOLN IS 24 HRS FASTER COMPARED TO THE ECMWF IN LIFTING THIS FEATURE EAST OF THE AREA. THE GFS IS DRY AFTER WEDS WITH THE TROUGH OVER MISSOURI VALLEY BY 12Z THURSDAY...WHILE THE ECMWF HAS THIS FEATURE OVER THE SAME AREA BY 12Z FRIDAY. INHERITED FCST WAS DRY WEDS NIGHT AND INTRODUCED POPS FOR THIS PERIOD AS BOTH MODELS HAVE TRENDED SLOWER. WILL HOLD OFF ON INTRODUCING POPS FOR THURSDAY FOR NOW AND WAIT FOR THE MODELS TO COME INTO BETTER AGREEMENT. AFTER UNSEASONABLY COOL HIGHS IN THE 70S FOR WEDNESDAY AND THURSDAY...HIGHS WILL REBOUND BACK INTO THE 80S FOR THURSDAY AND FRIDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1236 PM CDT SAT AUG 23 2014 MVFR OR LOWER STRATUS CONTINUES TO IMPACT MOST AREA TERMINALS EARLY THIS AFTERNOON...BUT THE LATEST NEAR TERM GUIDANCE INDICATES SOME DISSIPATION BACK TO VFR BY MID TO LATE AFTERNOON FOR MOST TERMINALS. THUNDERSTORMS ARE ANTICIPATED OVER MUCH OF THE SANDHILLS REGION THIS EVENING AND OVERNIGHT...FIRST FORMING OVER THE HIGHER TERRAIN OF WESTERN NEBRASKA...THEN SPREADING NORTHEAST OVERNIGHT. BRIEF HEAVY RAINFALL...HAIL AND ERRATIC WIND WOULD ACCOMPANY ANY STORM THAT DEVELOPS. OTHERWISE DRIER AIR TO FOLLOW THE STORMS SHOULD ALLOW FOR WIDESPREAD VFR THROUGH THE REMAINDER OF THE 18Z TAF PERIOD. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CLB SHORT TERM...JACOBS LONG TERM...CLB AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1238 PM CDT SAT AUG 23 2014 .UPDATE... ISSUED AT 532 AM CDT SAT AUG 23 2014 STRATUS IS BEING TO DEVELOP EARLY THIS MORNING AND THE HRRR IS DOING A DECENT JOB WITH THE LOW CLOUD DEPICTION. THE MODEL INDICATES THE MORE WIDESPREAD LOW CLOUD POTENTIAL PRIMARILY ALONG AND NORTH OF THE PLATTE RIVER...BUT CIGS ARE ALSO STARTING TO LOWER FARTHER SOUTH INTO NORTH CENTRAL KANSAS. CONFIDENCE IS NOT HIGH ON THE DEVELOPMENT OF FOG AS WINDS ARE FARILY STEADY FROM THE SOUTHEAST. MODELS SUGGEST THE LOW CLOUDS WILL PERSIST FOR AROUND THREE HOURS OR SO...BREAKING UP BY MID MORNING. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 402 AM CDT SAT AUG 23 2014 EARLY MORNING CONVECTION WAS LIFTING OUT OF OUR CWA ON THE NOSE OF THE LLVL AND AS THE WARM FRONTAL BOUNDARY LIFTS NORTHWARD AHEAD OF AN UPPER LOW EDGING EAST FM IDAHO. SEVERE WEATHER REPORTS FROM THE EVENING CONVECTION WERE LIMITED HOWEVER RAINFALL WAS WIDESPREAD WITH SEVERAL LOCATIONS RECEIVING AMOUNTS NEAR OR ABOVE ONE INCH. WINDS WILL TRANSITION SOUTHERLY AS THE WARM FRONTAL BOUNDARY LIFTS INTO THE DAKOTAS TODAY AND A PERIOD OF BREEZY CONDITIONS ARE FORECAST DURING THE AFTERNOON WITH GUSTS OF 25 TO 30 MPH POSSIBLE...ESPECIALLY FOR OUR SOUTHEASTERN ZONES. AFTERNOON TEMPS ARE LOOKING SIMILAR TO THE LAST FEW DAYS WITH HIGHS RANGING FROM THE UPPER 80S TO THE MID/UPPER 90S...AIDED BY DEEPER MIXING. CANNOT RULE OUT AN ISOLATED TSTM IN THE AFTN IN WAA AHEAD OF THE UPPER TROUGH MOVING INTO MT/WY. UNCERTAINTY EXISTS IN THE CONVECTIVE POTENTIAL TONIGHT AS THE UPPER LOW EDGES INTO THE WESTERN DAKOTAS AND A COLD FRONTAL BOUNDARY ADVANCES EASTWARD FM THE HIGH PLAINS AND REACHES OUR WESTERN CWA PRIOR TO DAYBREAK. WAA AHEAD OF THE FRONT AND CONVERGENCE/DYNAMICS ALONG THE BAROCLINIC ZONE MAY LEAD TO ISOLATED/SCATTERED STORMS. IF STORMS DEVELOP...LACK OF GOOD SHEAR AND MARGINAL INSTABILITY SHOULD LIMIT STORMS FROM BECOMING SEVERE. AS THE COLD FRONT ARRIVES LATE TONIGHT...DRIER AIR ADVECTS SOUTHEAST BEHIND THE BOUNDARY WITH DPS DROPPING OFF TO THE 50S BY SUNDAY MORNING IN OUR WESTERN ZONES. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 402 AM CDT SAT AUG 23 2014 ALOFT: A FAIRLY AMPLIFIED ERN USA RIDGE/WRN USA TROF SUN WILL GRADUALLY DEAMPLIFY NEXT WEEK AND BECOME PROGRESSIVE. A POTENT CLOSED LOW WILL WILL BE EJECTING OUT OF THE TROF...CROSSING THE DAKOTAS SUN. THIS WILL LEAVE A +TILT TROF BEHIND OVER THE WRN USA MON-TUE. THIS TROF WILL ADVANCE INTO THE PLAINS WED AND THE LAST 2-3 RUNS OF THE EC/GFS/GEM/UKMET ARE IN DECENT AGREEMENT THRU THIS TIME FRAME. AGREEMENT BREAKS DOWN THU AND WE SAW HINTS OF THIS 24 HRS AGO. THE GFS KEEPS THE TROF PROGRESSIVE WHILE THE UKMET/EC AND SOME OF THE PAST 4 GEM CYCLES BREAK THE BASE OF THE TROF OFF FROM THE WESTERLIES WHICH BECOME RE-ESTABLISHED OVER SRN CANADA. THE GFS DEVELOPS NW FLOW OVER THE PLAINS WHILE MOST OTHER MODELS HAVE THE TROF AXIS OVERHEAD. SURFACE: A COOL FRONT WILL BE CROSSING THE FCST AREA SUN MORNING. THIS FRONT WILL BECOME STATIONARY ACROSS NRN KS MON AS IT BECOMES PARALLEL WITH THE FLOW ALOFT. THE SRN FRINGE OF CANADIAN HIGH PRES WILL BUILD IN MON-TUE. HOWEVER...WITH THE TROF REMAINING TO THE W THE FRONT WILL BE CONVECTIVELY ACTIVE HAZARDS: MULTIPLE ROUNDS OF TSTMS APPEAR LIKELY WITH MON NIGHT CONTINUING AS THE HIGHEST CONFIDENCE. EXCESSIVE RAINFALL COULD BE A PROBLEM IF THESE TSTM CLUSTERS TRACK OVER SIMILAR AREAS AND WE MAY SEE HYDRO/FLOODING CONCERNS. THE DAILY DETAILS... SUN: WHILE THE BEST LOW-LVL DEWPOINTS WILL BE WHISKED AWAY BY THIS TIME FRAME...THERE IS A NARROW TONGUE OF 10-12C 850 MB DWPTS ALONG THE COOL FRONT. A COUPLE OF SHWRS/TSTMS MAY BE ON-GOING JUST NW OF THE FCST AREA AT DAYBREAK. PRESENT INDICATIONS ARE THAT THEY WILL DISSIPATE. BY AFTERNOON THIS MOIST TONGUE WILL BE OVER THE SE FRINGE OF THE FCST AREA...AND COULD SUPPORT DEVELOPMENT A TSTM OR TWO. SREF MLCAPE 2000-3000 J/KG. DEEP LAYER SHEAR AROUND 25 KTS WILL SUPPORT SEVERE MULTI-CELL CONVECTIVE MODE. SUN NIGHT: A LEE-SIDE LOW WILL BECOME ESTABLISHED NEAR PUB IN THE RIGHT REAR QUADRANT OF AN 80 KT ULJ. THE RESULT WILL BE UPSLOPE FLOW...THE DEVELOPMENT OF A LLJ AND ENHANCED THETA-E ADVECTION. RICH 850 MB DWPTS WILL ADVECT BACK INTO THE REGION LEADING TO DESTABILIZATION AND TSTM DEVELOPMENT OVER THE HIGH PLAINS. SOME OF THIS SHOULD FILTER E INTO THE FCST AREA AFTER MIDNIGHT. MON: LOTS OF UNCERTAINTY ON TEMPS. DEPENDENT ON THE AMT OF CLOUD COVER AND LINGERING TSTM ACTIVITY FROM SUN NIGHT. THIS WILL ACT TO REINFORCE THE FRONT VIA DIFFERENTIAL HEATING. AREAS N OF I-80 COULD STAY IN THE 70S WHILE N-CNTRL KS WILL BAKE INTO THE MID 90S. ANY LEFTOVER TSTM ACTIVITY SHOULD WANE DURING THE DAY. CANT RULE OUT AN ISOLATED LATE DAY TSTM OR TWO. MON NIGHT: THE MODELS CONT TO ADVERTISE MCS DEVELOPMENT AT THE NOSE OF THE LLJ. HIGH POPS ARE IN ORDER ESPECIALLY N OF HWY 6. TUE: PROBABLY A LULL IN TSTM ACTIVITY IN THE WAKE OF THE MCS. AGAIN TEMPS ARE HIGHLY UNCERTAIN. WITH CONVECTIVELY REINFORCED FRONT STILL NEAR THE KS-NEB BORDER...LATE DAY TSTM DEVELOPMENT CANT BE RULED OUT. WED-THU: FOR WHAT IT`S WORTH POTENTIAL EXISTS FOR MORE TSTMS AND IF MCS ACTIVITY IS PLACED JUST RIGHT...MULTIPLE EPISODES COULD RESULT IN EXCESSIVELY HEAVY RAINFALL. THE 18Z/22 GFS ENSEMBLES SHOW ABOVE NORMAL UNCERTAINTY IN TEMPS WED- THU. IF THE EC TURNS OUT CORRECT...WE COULD SEE SUBSTANTIAL CLOUD COVER/STRATUS TRAPPED BENEATH THE FRONT AS THE UPPER TROF MOVES IN. THE GEM/EC/GFS/DGEX ALL INDICATE POTENTIAL FOR 1 OR BOTH DAYS WITH DAYTIME TEMPS JAMMED WAYYYY BELOW NORMAL /AS COOL AS UPPER 60S TO NEAR 70/. FRI: DRY WITH SEASONABLE TEMPS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1235 PM CDT SAT AUG 23 2014 SLOWLY ERODING LOW CLOUDS OUT OF SOUTH CENTRAL NEBRASKA. GRAND ISLAND PRETTY MUCH IN THE CLEAR IT APPEARS...WHILE KEARNEY MAY SKIRT WITH SOME SCATTERED AFTERNOON CLOUDS BUT OVERALL TREND SHOULD BE CLEARING OUT. WINDS WILL CONTINUE TO INCREASE AHEAD OF DEEPENING LOW LEVEL TROUGH WITH GUSTS OVER 20 MPH NOT UNCOMMON. PRECIPITATION WHICH DEVELOPS TO THE WEST TONIGHT COULD MOVE INTO THE AREA LATE IN THE FORECAST...BUT WAS NOT CONFIDENT IN ITS COVERAGE TO ADD TO FORECAST AT THIS TIME. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...FAY SHORT TERM...FAY LONG TERM...HALBLAUB AVIATION...NOAA/NWS/MORITZ
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1236 PM CDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 408 AM CDT SAT AUG 23 2014 A SURFACE ANALYSIS AT 07Z INDICATED A FRONT DRAPED ACROSS SOUTHERN SOUTH DAKOTA WHILE ANOTHER WAS DRAPED FROM WEST CENTRAL INTO NORTHEAST KANSAS. A FAIRLY LARGE MCS WITH EMBEDDED MCVS CONTINUES TO LIFT FROM EASTERN AND NORTHERN NEBRASKA INTO SOUTH DAKOTA. MOST IF NOT ALL SHOWER ACTIVITY HAS ENDED FROM SOUTHWEST NEBRASKA INTO THE CENTRAL SANDHILLS. TEMPERATURES AND DEWPOINTS RANGING IN THE 60S ACROSS WRN AND NCTRL NEBR. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 408 AM CDT SAT AUG 23 2014 FOR TODAY... MODELS ARE IN FAIRLY GOOD AGREEMENT WITH A PV ANOMALY AND MID LEVEL DISTURBANCE LIFTING NORTHEAST FROM SOUTHERN UTAH CURRENTLY AND INTO NORTHEAST COLORADO BY 00Z THIS EVENING. ALONG WITH PEAK HEATING...THIS WILL PROVIDE AN INCREASE TO 30 POPS AFTER 21Z TODAY ACROSS THE NWRN HALF OF FA AND A SLIGHT CHC TO SOUTHEAST AREAS. A FAIRLY CLOUDY MORNING BASED ON RAP MODEL TIME SECTION AND LATEST SATELLITE IMAGERY. AFTERNOON CLEARING TO PARTLY CLOUDY EXPECTED FOR HIGHS FROM LOW 80S NORTHWEST TO UPPER 80S SOUTHWEST. FOR TONIGHT... THE ARW AND NMM MODELS FAVORED WHICH PERFORMED THE BEST WITH CURRENT SYSTEM EXITING THE AREA. BEST OVERALL PRECIPITATION CHANCES THIS EVENING WITH SYSTEM PASSAGE ARE 30-50 POPS WEST OF AN IML-ANW LINE AND 20-30 POPS FOR AREAS EAST. STORM MOTION WILL BE TO THE NORTHEAST AT 15 KTS. MUCH LESS RISK FOR LOCALLY HEAVY RAINFALL AS SOUNDINGS INDICATE WARM RAIN PROCESSES NOT OPERATING. NEVERTHELESS AREAS ACROSS THE WEST THIS EVENING MAY RECEIVE A TENTH TO QUARTER INCH OF NEW RAINFALL. POPS LOWERING TO 20 PERCENT AFTER MIDNIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 408 AM CDT SAT AUG 23 2014 AN ACTIVE WEATHER PATTERN WILL BE IN PLACE THROUGH THIS PERIOD WITH MULTIPLE CHANCES FOR RAIN AND COOLER TEMPERATURES EXPECTED FOR MUCH OF THE WEEK. THE UPPER LEVEL LOW NOW OVER IDAHO WILL CONTINUE TO IMPACT THE FORECAST AREA THROUGH THE FIRST PART OF THIS PERIOD. THE CURRENT FORECAST REMAINS DRY FOR SUNDAY AS THE MODELS SHOW A LACK OF MOISTURE ACROSS THE AREA. SEVERAL MODELS ARE INDICATING A NARROW BAND OF DEVELOPMENT MAINLY ACROSS CENTRAL NEBRASKA ALONG A COLD FRONT THAT LOOKS TO PUSH ACROSS THE FORECAST AREA DURING THE MORNING HOURS. THERE WILL BE SOME MID LEVEL SUPPORT AS THE UPPER LEVEL LOW LIFTS INTO NORTHWEST NORTH DAKOTA...DRAGGING WEAK SHORTWAVE ENERGY ACROSS THE CENTRAL PLAINS. WILL MONITOR FOR ANOTHER FORECAST CYCLE TO SEE IF THIS TREND CONTINUES AND IF SO...MAY NEED TO ADD SOME PRECIPITATION CHANCES FOR PART OF THE DAY SUNDAY. ALSO...A GOOD POOL OF COLD AIR WILL BE CIRCULATING AROUND THE SYSTEM...WITH MUCH COOLER AIR BEING DRAWN DOWN INTO NEBRASKA. BY 00Z TUESDAY THE MODELS ARE LIFTING THE SYSTEM FURTHER NORTH...ALLOWING WARM AIR ADVECTION TO BEGIN ACROSS THE SOUTH AND WESTERN PARTS OF THE AREA. WITH THE COOLER TEMPERATURES AND EXPECTING AT LEAST PARTIAL CLOUD COVER THE FORECAST HIGHS ARE NOW RANGING FROM THE MID 70S TO THE MID 80S. AN UPPER LEVEL LOW NOW MOVING INTO NORTHWEST CANADA OUT OF THE GULF OF ALASKA WILL DIG SOUTH INTO THE NORTHWEST PORTION OF THE CONUS BY MONDAY WHILE THE UPPER LOW TO THE NORTH PUSHES FURTHER NORTH AND EAST AWAY FROM THE AREA. THIS WILL KEEP THE CENTRAL PLAINS UNDER SOUTHWEST FLOW TO HELP BRING MOISTURE UP INTO THE AREA THROUGH MID-WEEK. FOR SUNDAY NIGHT...THE MODELS CONTINUE TO DEVELOP CONVECTION OVER NORTHEAST COLORADO...WHICH THEN SPREADS NORTHEAST INTO WESTERN NEBRASKA. THE AREA WILL BE IN THE FAVORED RIGHT ENTRANCE REGION OF THE JET AND WITH AN INCREASING LOW LEVEL JET /THOUGH NOT PARTICULARLY STRONG/ INTO THE EVENING THERE MIGHT BE ENOUGH FORCING TO KEEP THESE STORMS GOING OVERNIGHT INTO NEBRASKA SO MADE VERY LITTLE CHANGES TO ONGOING PRECIPITATION FORECAST. DURING THE DAY MONDAY...ATTEMPTED TO SHOW A TREND OF THIS ACTIVITY MOVING NORTHEAST AND THROUGH THE FORECAST AREA. MODELS SEEM TO BE SLOWING THE ADVANCEMENT OF THESE STORMS FROM PRIOR MODEL RUNS SO DON/T HAVE A HIGH DEGREE OF CONFIDENCE ON THE TIMING NOR PLACEMENT OF THESE STORM CHANCES. KEPT LIKELY CHANCES FOR RAIN FOR PORTIONS OF THE FORECAST AREA FOR MONDAY NIGHT. STILL LOOKS TO BE A SURFACE LOW SOMEWHERE OVER EASTERN COLORADO/WESTERN KANSAS WITH WARM FRONT EXTENDING INTO CENTRAL AND NORTHEAST NEBRASKA. THE MODELS ARE IN GOOD AGREEMENT WITH A WEAK SHORTWAVE TROUGH MOVING OUT OF THE FOUR CORNERS AND ACROSS THE CENTRAL PLAINS BY 12Z TUESDAY WHILE THE MAIN TROUGH REMAINS OFF TO THE WEST OVER IDAHO AND NEVADA. THE COMBINATION OF FORCING FROM THE SHORTWAVE TROUGH MOVING ACROSS THE AREA AND AN INCREASING LOW LEVEL JET BEING FOCUSED INTO WESTERN NEBRASKA FEEL THAT MONDAY NIGHT HAS THE HIGHEST CHANCES FOR RAINFALL. COULD BE ANOTHER DAY SIMILAR TO YESTERDAY WHERE THERE IS ENOUGH SHEAR AND INSTABILITY TO AT LEAST MENTION A THREAT FOR A FEW SEVERE STORMS...BUT THIS WILL DEPEND ON CONVECTION DURING THE DAY MONDAY AND WITH PRECIPITABLE WATER VALUES OVER 120 PERCENT OF NORMAL AND WARM CLOUD DEPTHS EXCEEDING 3500M STORMS SHOULD BE EFFICIENT RAIN MAKERS SO MAY BE DEALING WITH MORE OF A HEAVY RAIN THREAT. TUESDAY THROUGH FRIDAY...THE LONG RANGE MODELS BEGIN TO DIVERGE WITH HOW THEY HANDLE HOW THE TROUGH TO WEST BEHAVES. THE GFS QUICKLY PUSHES IT EAST THROUGH THE PLAINS AND INTO THE GREAT LAKES REGION BY THURSDAY WHILE THE ECMWF AND GEM ARE SLOWER AND DON/T MOVE IT OUT OF THE CENTRAL PLAINS UNTIL LATER IN THE WEEK. THIS WILL HAVE AN IMPACT ON THE SENSIBLE WEATHER AS THE SLOWER SOLUTION WOULD LINGER PRECIPITATION ACROSS THE AREA LONGER...AT LEAST THROUGH THURSDAY...WHILE THE GFS HAS A DRY FORECAST BY WEDNESDAY MORNING. HAVE NOT JUMPED ON THE SLOWER SOLUTION BUT DID LEAVE SOME SLIGHT CHANCES IN THE FORECAST THROUGH THURSDAY. WHAT IS FAIRLY CERTAIN EITHER WAY IS THAT TEMPERATURES WILL BE COOLER FOR THE WEEK. WITH PRECIPITATION AND CLOUD COVER...SOME DAYS MAY SEE HIGHS STRUGGLE TO GET INTO THE LOW AND MID 70S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1236 PM CDT SAT AUG 23 2014 MVFR OR LOWER STRATUS CONTINUES TO IMPACT MOST AREA TERMINALS EARLY THIS AFTERNOON...BUT THE LATEST NEAR TERM GUIDANCE INDICATES SOME DISSIPATION BACK TO VFR BY MID TO LATE AFTERNOON FOR MOST TERMINALS. THUNDERSTORMS ARE ANTICIPATED OVER MUCH OF THE SANDHILLS REGION THIS EVENING AND OVERNIGHT...FIRST FORMING OVER THE HIGHER TERRAIN OF WESTERN NEBRASKA...THEN SPREADING NORTHEAST OVERNIGHT. BRIEF HEAVY RAINFALL...HAIL AND ERRATIC WIND WOULD ACCOMPANY ANY STORM THAT DEVELOPS. OTHERWISE DRIER AIR TO FOLLOW THE STORMS SHOULD ALLOW FOR WIDESPREAD VFR THROUGH THE REMAINDER OF THE 18Z TAF PERIOD. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...ROBERG SHORT TERM...ROBERG LONG TERM...BROOKS AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
351 PM EDT SAT AUG 23 2014 .SYNOPSIS... A COLD FRONT TO OUR SOUTH WILL BE MOVING AWAY FROM THE AREA BY SUNDAY MORNING. PROGRESSIVELY DRIER AND COOLER AIR WILL BE PUSHING SOUTH IN THE WAKE OF THE FRONT AND THIS WILL ALLOW FOR FAR FEWER SHOWERS AND THUNDERSTORMS SUNDAY. HIGH PRESSURE WILL EXPAND SOUTH ACROSS THE AREA NEXT WEEK WITH ITS INFLUENCE BEGINNING TO WANE DURING THE MIDDLE AND LATER PORTIONS OF NEXT WEEK. WE WILL BE MONITORING FOR THE DEVELOPMENT OF TROPICAL CYCLONE CRISTOBAL IN THE COMING DAYS. CRISTOBAL MAY MAKE ITS CLOSEST APPROACH TO THE CAROLINA COAST MID OR LATE NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... AS OF 300 PM SATURDAY...SHOWERS AND THUNDERSTORMS BEGINNING TO BECOME MORE WIDESPREAD ACROSS THE AREA...IN A TREND THAT WILL LIKELY CONTINUE INTO TONIGHT. THE CWA IS BISECTED THIS AFTERNOON BY A COLD FRONT...WHICH IS ALIGNED ROUGHLY FROM MYRTLE BEACH...TO FLORENCE...AND UP TOWARDS CHARLOTTE. THIS BOUNDARY AT THE SURFACE IS DIFFICULT TO IDENTIFY DUE TO THE LIGHT GRADIENT SURROUNDING IT KEEPING WINDS LIGHT...BUT WINDS NORTH OF THE BOUNDARY ARE PRIMARILY FROM THE NORTH...WITH VARIABLE DIRECTIONS TO THE SOUTH. ALOFT...FRONT IS MORE EASILY IDENTIFIABLE ON PW IMAGERY...AS MUCH DRIER AIR IS FILTERING IN BEHIND THE FRONT. IT IS INTERESTING TO NOTE...HOWEVER...THAT CONVECTION IS BECOMING WIDESPREAD IN THE DRIER COLUMN NORTH OF THE BOUNDARY. ALTHOUGH THIS SEEMS TO BE COUNTER-INTUITIVE...THE BLENDED/LAYERED PWAT PRODUCT FROM CIRA SHOWS THE DRY AIR CONFINED TO THE LAYER ABOVE 700MB...WHILE MOISTURE IS ACTUALLY INCREASING BELOW 850MB. THIS WILL CONTINUE TO BE THE CASE THROUGH TONIGHT AS EVIDENCED BY BOTH RUC AND NAM FORECAST PROFILES SHOWING PWATS INCREASING TO WELL ABOVE 2 INCHES THIS EVENING AND TONIGHT...BEFORE DRYING OCCURS LATE. TRYING TO DETERMINE WHERE CONVECTION WILL BE MOST WIDESPREAD TODAY IS TRICKY...BUT HIGH RES ARW/NAM/HRRR ALL SUGGEST THE BEST FOCUS WILL BE ACROSS NC COUNTIES THROUGH THE EVE...WITH LESSER CHANCES IN SC. THIS IS LIKELY DUE TO A SHORTWAVE WHICH IS PROGGED TO DROP ACROSS THE AREA...DIRECTED ON NW FLOW BETWEEN A TROUGH OVER NEW ENGLAND A RIDGE ACROSS THE MS VLY. AS THIS IMPULSE MOVES OVERHEAD...IT WILL TAP INTO AN ENVIRONMENT CHARACTERIZED BY STRONG THETA-E RIDGING AND MLCAPE OVER 2000 J/KG. HAVE ATTEMPTED TO TIME THE HIGHEST POP TO CORRELATE WITH DEEPEST FORECAST-SOUNDING SATURATION AND THE HIGH RES GUIDANCE...BUT AT LEAST SCT CONVECTION WILL LIKELY BE ONGOING FOR A MANY-HOUR PERIOD...CENTERED AROUND 7PM. THIS SUGGESTS THAT SHOWERS WILL PERSIST SEVERAL HOURS AFTER NIGHTFALL THANKS TO THE FORCING ALOFT...AND HAVE POP WANING AFTER MIDNIGHT. WHILE SEVERE IS NOT ANTICIPATED...ESPECIALLY WITH THE DRYING OCCURRING ALOFT AND SOME CONFLUENCE WITHIN THE EXIT REGION OF AN UPPER JET MOVING NEARBY...ISOLATED GUSTY WINDS ARE POSSIBLE AS IS TYPICAL WITH NW FLOW EVENTS. HEAVY RAINFALL WILL BE THE PRIMARY THREAT THROUGH THE PERIOD HOWEVER. THE FRONT WILL FINALLY GET KICKED SOUTH TONIGHT...AND SHOULD CLEAR THE CWA BY DAYBREAK SUNDAY. A DEVELOPING NE SURGE BEHIND THE BOUNDARY WILL HELP DRIVE THIS FRONT SOUTH...BUT ANY COOL ADVECTION WILL BE A BIT LATE TO SIGNIFICANTLY AFFECT MINS TONIGHT. HAVE SIDED CLOSELY WITH THE MET NUMBERS WHICH HAVE PERFORMED QUITE WELL THE PAST FEW NIGHTS...AND LOWS WILL DROP TO AROUND 70 IN THE FAR NORTH...TO NEAR 75 ALONG THE SOUTHERN GRAND STRAND. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... AS OF 300 PM SATURDAY...A COLD FRONT WILL HAVE MOVED THROUGH THE ENTIRE FORECAST AREA BEFORE 12Z SUN. THE INFLUX OF DRIER AIR WILL BE STRONGEST AND DEEPEST ACROSS THE NORTHERN ZONES SUN. THE DRY AIR WILL BE ESPECIALLY PRONOUNCED IN THE MID LEVELS...ABOVE 10-12 KFT. AN ONSHORE FLOW BELOW 10 KFT WILL KEEP THE LOWER LEVELS OF THE COLUMN MORE MOIST. A SHORTWAVE PUSHING DOWN THE SOUTHEAST COAST MAY TOUCH OFF SOME SHALLOWER CONVECTION. WILL CARRY A SLIGHT CHANCE TO SMALL CHANCE OF SHOWERS AND THUNDERSTORMS ON SUNDAY WITH THE RISK DECREASING FROM NORTH TO SOUTH AS THE DAY PROGRESSES. PRECIPITABLE WATER VALUES WILL BE DROPPING BELOW THREE-QUARTERS OF AN INCH SUN NIGHT AS MUCH DRIER AIR OVERWHELMS THE COLUMN DOWN TO THE SURFACE. THUS...WILL NOT CARRY ANY POPS BEYOND NIGHTFALL. A DEEP AND TIGHTENING NE FLOW WILL BE PRESENT MON AND MON NIGHT AS A WEDGE OF HIGH PRESSURE BUILDS STRONGLY ACROSS WESTERN NORTH CAROLINA AND THE UPSTATE OF SOUTH CAROLINA. AT THE SAME TIME...DEVELOPING TROPICAL LOW PRESSURE ACROSS THE BAHAMAS WILL RESULT IN A TIGHTENING PRESSURE GRADIENT. AN INVERTED TROUGH MAY BEGIN TO DEVELOP DURING THIS TIME AND IF IT COMES CLOSE ENOUGH TO THE COAST...A FEW SHOWERS MAY IMPINGE ONTO THE COAST. AT THIS TIME...WILL KEEP ANY MENTION OF CONVECTION OFFSHORE...BUT SHOW SOME INCREASING CLOUD COVER AS THE COLUMN DOES BEGIN TO MOISTEN BACK UP IN THE LOWER LEVELS. HIGH TEMPS WILL BE MAINLY NEAR TO A FEW DEGREES BELOW NORMAL THIS PERIOD AS WE WILL BE UNDER A NE FLOW REGIME. HIGHS BOTH DAYS WILL BE IN THE MID AND UPPER 80S. DEWPOINTS WILL ALSO BE CONSIDERABLY LOWER THAN RECENT DAYS AND SO FOR MOST...IT WILL BE MUCH MORE PLEASANT. LOWS WILL BE BELOW NORMAL AND MAINLY IN THE MID TO UPPER 60S. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 300 PM SATURDAY...THE EXTENDED CONTINUES TO BE DOMINATED BY MID LEVEL HIGH PRESSURE MOVING FROM THE MISSISSIPPI VALLEY TO THE SOUTHEAST BY NEXT WEEKEND. AT THE SURFACE HIGH PRESSURE WILL BE THE MAIN FEATURE FOR TUESDAY AND WEDNESDAY WITH A COOL NORTHEAST FLOW. THE HIGH BECOMES MORE DIFFUSE THURSDAY...A LITTLE EARLIER THAN PREVIOUS GUIDANCE. THE SYSTEM FOR LATE IN THE WEEK LOOKS CONSIDERABLY WEAKER AS WELL. CHANGES TO THE FORECAST THIS AFTERNOON ARE MINIMAL. I DID INCREASE POPS FOR FRIDAY AND SATURDAY TO MATCH OTHER OFFICES BETTER BUT THE VALUES ARE STILL LOWER THAN THIS TIME YESTERDAY. THE TEMPERATURE FORECAST HAS INCREASED ESPECIALLY FOR THURSDAY AND FRIDAY WITH READINGS NEARING OR EVEN EXCEEDING CLIMATOLOGY SLIGHTLY FOR THESE PERIODS INCLUDING SATURDAY. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 18Z...A COLD FRONT WAS LOCATED IN THE VICINITY OF THE TERMINALS THIS AFTERNOON. ISOLATED SHOWERS WERE DEVELOPING ALONG THE SEA BREEZE AND MAY IMPACT ILM/CRE/MYR DURING THE NEXT FEW HOURS. THE FRONT WILL SHIFT SOUTH OF ALL TERMINALS TONIGHT. OTHER THAN SCATTERED THUNDERSTORMS ALONG THE SEA BREEZE...CONVECTION WILL BE ISOLATED THIS AFTERNOON. HOWEVER...AN UPPER IMPULSE WILL MOVE TOWARDS THE AREA THIS EVENING...WHICH WILL SET OFF MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS THE AREA. STILL SOME UNCERTAINTY INTO THE TIMING AND COVERAGE OF THIS ACTIVITY...BUT HAVE ENOUGH CONFIDENCE TO KEEP VCSH AT THE TERMINALS UNTIL AFTER MIDNIGHT. LIGHT WINDS THIS AFTN WILL BE PRIMARILY FROM THE EAST...WITH MINOR FLUCTUATIONS TO SE OR NE AT TIMES. HEAVIEST SHOWERS SHOULD END N-S TONIGHT. POST FRONTAL MVFR CIGS ARE EXPECTED WITH REASONABLE CONFIDENCE OF POST-FRONTAL IFR AT KFLO/KLBT OVERNIGHT. MVFR SHORTLY AFTER SUNRISE SHOULD IMPROVE TO VFR AT THE NORTHERN AND COASTAL TERMINALS INITIALLY...AND KFLO BY MID MORNING. WINDS WILL BECOME PREDOMINATELY NE 10-15 KT AFTER SUNRISE. EXTENDED OUTLOOK...EXPECT VFR/NSW TO PREVAIL THROUGH TUES AS HIGH PRESSURE RIDGES OVER THE EAST COAST IN THE WAKE OF THE COLD FRONT. A CHANCE OF SHRA WED. VFR/NSW THURS. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM SATURDAY...COLD FRONT IS SLOWLY DROPPING SOUTH ACROSS THE WATERS TODAY...AND ALTHOUGH IS TOUGH TO LOCATE EXACTLY...APPEARS TO BE JUST SOUTH OF MYRTLE BEACH AT THIS TIME. THE WATERS NORTH OF THIS BOUNDARY ARE EXPERIENCING E/NE WINDS OF 5-10 KTS...WHILE SOUTH OF THE FRONT WINDS ARE LIGHT AND VARIABLE. THE EXCEPTION IS ACROSS AMZ250 WHERE WINDS ARE GUSTING UP TO 15 KTS FROM THE NE...THE BEGINNING OF WHAT WILL BE AN INCREASING SURGE TONIGHT. THIS FRONT WILL SLOWLY DROP THROUGH ALL THE WATERS OVERNIGHT...LEAVING INCREASING NE WINDS IN ITS WAKE...AND BY SUNDAY MORNING WINDS WILL BE NE AT 15-20 KTS ACROSS ALL THE WATERS. WAVE HEIGHTS WILL BUILD ON THESE RISING WINDS...SLOWLY AT FIRST TO 2-3 FT TONIGHT...BUT MORE QUICKLY LATE...AND WILL BECOME 3-4 FT WITH A FEW 5 FTERS IN THE NORTHERN WATERS BY SUNDAY MORNING. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 PM SATURDAY...THE GRADIENT WILL BE TIGHTENING UP DURING THIS PERIOD. A NE SURGE SUNDAY WILL BECOME FORTIFIED BY A TIGHTENING PRESSURE GRADIENT BETWEEN HIGH PRESSURE ACROSS THE NORTHEAST U.S. AND A DEVELOPING TROPICAL LOW ACROSS THE BAHAMAS. THIS WILL SERVE TO NOT ONLY PROLONG THE NE FLOW...BUT TO INCREASE ITS MAGNITUDE. THUS...A SMALL CRAFT ADVISORY HAS BEEN ISSUED BEGINNING SUNDAY MORNING. WINDS WILL COMMONLY BE SUSTAINED AT 20 TO 25 KT. A NE FETCH WILL BUILD SEAS TO 4 TO 7 FT AND 8 FT OR HIGHER BEYOND 20 NM. LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 300 PM SATURDAY...THE MARINE COMMUNITY CAN EXPECT A NORTHEAST FLOW TUESDAY ON THE ORDER OF 15-20 KNOTS. THIS FLOW WILL DIMINISH QUITE A BIT WEDNESDAY ESSENTIALLY BECOMING VARIABLE BY DAYS END. FOR THURSDAY A VERY LIGHT FLOW CAN BE EXPECTED AS THE WATERS ARE IN BETWEEN RETREATING HIGH PRESSURE TO THE NORTH AND THE BUILDING BERMUDA RIDGE. WILL LIKELY SEE WINDS MORE INFLUENCED BY THE SEA BREEZE THIS DAY. SIGNIFICANT SEAS CONTINUE TO BE PROBLEMATIC DEPENDING ON THE TRACK AND INTENSITY OF AL96. FORECAST SHOWS 2-6 FEET TUESDAY WITH AN INCREASE MOSTLY IN THE OUTER WATERS WEDNESDAY AND THURSDAY DUE ALMOST EXCLUSIVELY TO INCREASED SWELL COMPONENT FROM THE AFOREMENTIONED SYSTEM. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 AM SUNDAY TO 8 PM EDT MONDAY FOR AMZ250-252-254-256. && $$ NEAR TERM...JDW SHORT TERM...RJD LONG TERM...SHK AVIATION...JDW/MRR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 PM EDT SAT AUG 23 2014 .SYNOPSIS...A COLD FRONT WILL MOVE SOUTH ACROSS SOUTHERN VIRGINIA AND NORTH CAROLINA THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD SOUTH INTO THE REGION WITH COOLER AND DRIER CONDITIONS EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 255 PM SATURDAY... LATEST SURFACE ANALYSIS CONTINUES TO REVEAL A COMPLEX SURFACE PATTERN WITH THE BACK DOOR COLD FRONT NOW EXTENDING FROM WESTERN VIRGINIA EAST NEAR THE VA/NC BORDER AND THEN SOUTHEAST TOWARD THE MID CAROLINA COAST. A SURFACE TROUGH ALSO EXTENDS NORTH TO SOUTHEAST ACROSS THE NC/SC COASTAL REGION SEPARATING AN INCREASINGLY DEEP EASTERLY FLOW AS NOTED BY THE HMT-SEPS WIND PROFILER NEAR NEW BERN. A WEAK SURFACE LOW WAS ALSO ANALYZED JUST NORTH OF KCHS WITH A STEAMY 903/79 OBSERVED AT KGGE. A NORTHWEST FLOW ALOFT DOMINATES THE SYNOPTIC PATTERN WITH SEVERAL WAVES NOTED IN THE FLOW ALONG WITH A STRENGTHENING NORTHERN STREAM JET POISED TO DROP INTO THE MID ATLANTIC...NOTE THE 105KT JET AT 200 HPA AT KIAD THIS MORNING. MORNING RAOBS ACROSS THE CAROLINAS DEPICT A VERY MOIST ATMOSPHERE PRECIPITABLE WATER VALUES OF 120-135% OF NORMAL AT KGSO/KMHX RESPECTIVELY. NOT SURPRISED TO SHEE SHOWERS AND THUNDERSTORMS SLOWLY EXPANDING THIS AFTERNOON GIVEN THE ENHANCED FLOW ALOFT...AT LEAST ONE DISTURBANCE ALOFT OVER WESTERN VA AND MULTIPLE MECHANISMS FOR LOW LEVEL CONVERGENCE. CURRENT RADAR TRENDS DEPICT ONE AREA OF CONVECTION ACROSS THE NORTHERN PIEDMONT OF NC AND SOUTHERN VA IN PROXIMITY TO THE SURFACE FRONT AND A DISTURBANCE IN THE NW FLOW ALOFT. OTHER CONVECTION ACROSS THE COASTAL PLAIN AND COASTAL REGION IS DRIVEN IN A MORE UNSTABLE AIR MASS NEAR THE SURFACE TROUGH. USED A BLEND OF HRRR AND RAP HOURLY PRECIP FIELDS TO GENERATE THE HOURLY POP/QPF/WX GRIDS FOR THIS AFTERNOON AND EVENING. WHILE CONVECTIVE COVERAGE IS EXPECTED TO BE SOMEWHAT GENEROUS...MLCAPE VALUES WILL GENERALLY RANGE LESS THAN 1000 J/KG EXCEPT ACROSS THE SOUTHERN COASTAL PLAIN AND SANDHILLS WHERE VALUES MAY EXCEED 1500 J/KG WHICH SHOULD MINIMIZE CONVECTIVE INTENSITY IN MOST LOCATIONS. THE BEST FLOW ALOFT SHOULD REMAIN IN THE VA/MD/DE REGION WITH BULK SHEAR VALUES IN OUR CWA CLIMBING TO AROUND 25KTS. THE BIGGER THREAT WILL LIKELY BE ASSOCIATED WITH LOCALLY HEAVY RAIN WITH CELLS ORIENTED IN THE NW FLOW THAT REPEATEDLY MOVE OVER A GIVEN AREA. THE CONVECTIVE CONVERGE WILL INCREASE A BIT DURING THE NEXT SEVERAL HOURS WITH THE FOCUS GRADUALLY SHIFTING SOUTH INTO THE EVENING ALTHOUGH ISOLATED SHOWERS OR THUNDERSTORMS ARE POSSIBLE AT ANY TIME. A PROMINENT AREA OF CONVECTION UPSTREAM ACROSS IL/IN IS PROGGED TO WEAKEN AS IT MOVES SOUTHEAST AND SHOULD NOT IMPACT CENTRAL NC. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE UPPER 60S NORTHEAST TO LOWER 70S SOUTHWEST. -BLAES && .SHORT TERM /SUNDAY AND SUNDAY NIGHT /... AS OF 305 PM SATURDAY... THE COLD FRONT WILL HAVE PUSHED WELL SOUTH OF THE REGION BY SUNDAY MORNING WITH COOL HIGH PRESSURE BUILDING INTO CENTRAL NC IN ITS WAKE. WHILE MUCH DRIER AIR WILL MOVE INTO THE REGION AT MID AND UPPER LEVELS...SHALLOW LOW LEVEL MOISTURE WILL LINGER ESPECIALLY IN AN ARC FROM THE WESTERN PIEDMONT INTO THE SOUTHERN PIEDMONT AND EAST TOWARD THE SANDHILLS AND COASTAL PLAIN. A FEW SHOWERS MAY DEVELOP IN THIS REGION...ESPECIALLY EARLY ON SUNDAY...BUT LIMITED MOISTURE AND A CAPPING INVERSION SHOULD PRECLUDE DEEP CONVECTION AND LIMIT PRECIPITATION COVERAGE. A FAIR AMOUNT OF STRATO CUMULUS IS EXPECTED THOUGH. WITH A COOLER AIR MASS AND BELOW NORMAL THICKNESS VALUES... HIGHS ON SUNDAY WILL ONLY RANGE IN THE LOWER TO MID 80S. LOWS SUNDAY NIGHT WILL RANGE IN THE LOWER 60S. -BLAES && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 250 PM SATURDAY... FOR MONDAY THROUGH MID-WEDNESDAY...LOOK FOR FAIR WEATHER WITH NEAR- TO SLIGHTLY-BELOW NORMAL TEMPS (HIGHS IN THE LOW-MID 80S AND LOWS IN THE LOW 60S) AS HIGH PRESSURE BUILDS IN TO THE CAROLINAS FROM THE NORTH EARLY IN THE WEEK AND REMAINS OVER OUR AREA THROUGH MID-WEEK. FORECAST SOUNDINGS SUGGEST PWAT WILL RANGE FROM 0.5-1.0 INCHES DURING THIS TIME...WHICH IS WELL BELOW THE 1.35 INCH NORM FOR LATE AUGUST. A LARGE DEGREE OF UNCERTAINTY EXISTS FOR THE SECOND HALF OF THE WEEK...AS THIS PART OF THE FORECAST IS LARGELY DEPENDENT ON WHAT HAPPENS WITH INVEST 96L. TRACK MODELS HAVE BEEN QUITE SCATTERED AND LITTLE AGREEMENT AMONG THE GEFS/NAEFS MEMBERS. HOWEVER...ITS WORTH NOTING THAT THE TREND IN THE OPERATIONAL GFS HAS BEEN DEVELOPMENT AND SLOW NORTHWARD MOVEMENT E OF FL DURING THE FIRST HALF OF THE WEEK...THEN MOVING NNE ALONG BUT REMAINING OFF THE CAROLINA COAST LATE IN THE WEEK. THE LATEST ECMWF IS SIMILAR WITH THE EVOLUTION OF THIS SYSTEM...BUT IS FASTER AND ITS TRACK REMAINS FURTHER OFF THE COAST...SHOWING THE LOW MOVING NE AWAY FROM THE EAST COAST ON THURSDAY. ESSENTIALLY BOTH OF THESE SOLUTIONS WOULD KEEP CENTRAL NC FAR ENOUGH WEST OF THE SYSTEM SUCH THAT OUR AREA WOULD REMAIN IN FAIR WEATHER DURING THE SECOND HALF OF THE WEEK. TAKING THAT SYSTEM OUT OF THE PICTURE...OUR NEXT CHANCE FOR WET WEATHER WOULD COME DURING THE WEEKEND ASSOCIATED WITH EITHER THE NEXT TROUGH IN THE WESTERLIES (PER GFS) OR INCREASING MOISTURE IN THE RETURN FLOW AROUND THE RIDGE (PER THE ECWMF). IN SUMMARY...LOTS OF UNCERTAINTY FOR THE SECOND HALF OF THE LONG TERM...SO WILL STICK CLOSE TO CLIMO FOR TEMPS AND PERHAPS A LITTLE LOWER THAN CLIMO FOR POPS DURING THIS TIME. && .AVIATION /18Z SATURDAY THROUGH WEDNESDAY/... AS OF 225 PM SATURDAY... AS OF 18Z...SOME MVFR CONDITIONS MAINLY ASSOCIATED WITH CIGS PERSIST ACROSS PARTS OF THE NORTHEAST PIEDMONT AND COASTAL PLAIN. ELSEWHERE VFR CONDITIONS WITH MULTIPLE LOW TO MID CLOUD LAYERS ARE OBSERVED. SCATTERED SHOWERS AND THUNDERSTORMS WILL BECOME MORE NUMEROUS AND MOVE SOUTHEAST THIS AFTERNOON AND EVENING ACROSS CENTRAL NC AS A COLD FRONT AND AN UPPER LEVEL DISTURBANCE TRIGGERS AND THEN MAINTAIN SCATTERED CONVECTION. INITIALLY THE PRECIPITATION WILL BE MOST WIDESPREAD THIS AFTERNOON ACROSS THE COASTAL PLAIN...MAINLY EAST OF THE KRWI AND KFAY TERMINALS. ANOTHER AREA OF SHOWERS AND THUNDERSTORMS WILL ROTATE AND PUSH SOUTH ACROSS THE NORTHERN PIEDMONT THIS AFTERNOON AND THEN GRADUALLY SHIFT SOUTH LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING. THE CONVECTION WILL TEND TO SHIFT SOUTH...WEAKEN AND DECREASE IN COVERAGE LATER THIS EVENING AND OVERNIGHT. EXPECT LOCAL REDUCTIONS TO MVR AND INTERMITTENTLY IFR CONDITIONS IN SHOWERS AND THUNDERSTORMS. PREVAILING CEILINGS WILL ALSO DECREASE OVERNIGHT AS COOLER AIR MOVES INTO THE REGION WITH PERIODS OF IFR CONDITIONS IN LOW CLOUDS AND SOME FOG LIKELY TOWARD DAYBREAK WITH HEATING AND AN INFLUX OF DRIER AIR FROM THE NORTHEAST...CEILINGS SHOULD LIFT A COUPLE OF HOURS AFTER DAYBREAK WITH VFR CONDITIONS PREVAILING BY LATE OR EARLY AFTERNOON. LOOKING FURTHER AHEAD...HIGH PRESSURE AT THE SURFACE AND ALOFT WILL EXTEND INTO THE REGION FOR THE LATE SUNDAY THROUGH WEDNESDAY PERIOD BRINGING A PERIOD OF GENERALLY FAIR WEATHER. EXCEPTIONS WOULD INCLUDE THE POTENTIAL FOR SOME DAYBREAK FOG ON MONDAY AND TUESDAY MORNINGS...ESPECIALLY ACROSS THE COASTAL PLAIN AND PERHAPS A SHOWER ACROSS THE EASTERN SECTIONS IN A PERSISTENT NORTHEAST FLOW. -BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES SHORT TERM...BLAES LONG TERM...NP AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
255 PM EDT SAT AUG 23 2014 .SYNOPSIS...A COLD FRONT WILL MOVE SOUTH ACROSS SOUTHERN VIRGINIA AND NORTH CAROLINA THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD SOUTH INTO THE REGION WITH COOLER AND DRIER CONDITIONS EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 255 PM SATURDAY... LATEST SURFACE ANALYSIS CONTINUES TO REVEAL A COMPLEX SURFACE PATTERN WITH THE BACK DOOR COLD FRONT NOW EXTENDING FROM WESTERN VIRGINIA EAST NEAR THE VA/NC BORDER AND THEN SOUTHEAST TOWARD THE MID CAROLINA COAST. A SURFACE TROUGH ALSO EXTENDS NORTH TO SOUTHEAST ACROSS THE NC/SC COASTAL REGION SEPARATING AN INCREASINGLY DEEP EASTERLY FLOW AS NOTED BY THE HMT-SEPS WIND PROFILER NEAR NEW BERN. A WEAK SURFACE LOW WAS ALSO ANLAYZED JUST NORTH OF KCHS WITH A STEAMY 903/79 OBSERVED AT KGGE. A NORTHWEST FLOW ALOFT DOMINATES THE SYNOPTIC PATTERN WITH SEVERAL WAVES NOTED IN THE FLOW ALONG WITH A STRENGTHENING NORTHERN STREAM JET POISED TO DROP INTO THE MID ATLANTIC...NOTE THE 105KT JET AT 200 HPA AT KIAD THIS MORNING. MORNING RAOBS ACROSS THE CAROLINAS DEPICT A VERY MOIST ATMOSPHERE PRECIPITABLE WATER VALUES OF 120-135% OF NORMAL AT KGSO/KMHX RESPECTIVELY. NOT SURPRISED TO SHEE SHOWERS AND THUNDERSTORMS SLOWLY EXPANDING THIS AFTERNOON GIVEN THE ENHANCED FLOW ALOFT...AT LEAST ONE DISTURBANCE ALOFT OVER WESTERN VA AND MULTIPLE MECHANISMS FOR LOW LEVEL CONVERGENCE. CURRENT RADAR TRENDS DEPICT ONE AREA OF CONVECTION ACROSS THE NORTHERN PIEDMONT OF NC AND SOUTHERN VA IN PROXIMITY TO THE SURFACE FRONT AND A DISTURBANCE IN THE NW FLOW ALOFT. OTHER CONVECTION ACROSS THE COASTAL PLAIN AND COASTAL REGION IS DRIVEN IN A MORE UNSTABLE AIR MASS NEAR THE SURFACE TROUGH. USED A BLEND OF HRRR AND RAP HOURLY PRECIP FIELDS TO GENERATE THE HOURLY POP/QPF/WX GRIDS FOR THIS AFTERNOON AND EVENING. WHILE CONVECTIVE COVERAGE IS EXPECTED TO BE SOMEWHAT GENEROUS...MLCAPE VALUES WILL GENERALLY RANGE LESS THAN 1000 J/KG EXCEPT ACROSS THE SOUTHERN COASTAL PLAIN AND SANDHILLS WHERE VALUES MAY EXCEED 1500 J/KG WHICH SHOULD MINIMIZE CONVECTIVE INTENSITY IN MOST LOCATIONS. THE BEST FLOW ALOFT SHOULD REMAIN IN THE VA/MD/DE REGION WITH BULK SHEAR VALUES IN OUR CWA CLIMBING TO AROUND 25KTS. THE BIGGER THREAT WILL LIKELY BE ASSOCIATED WITH LOCALLY HEAVY RAIN WITH CELLS ORIENTED IN THE NW FLOW THAT REPEATEDLY MOVE OVER A GIVEN AREA. THE CONVECTIVE CONVERGE WILL INCREASE A BIT DURING THE NEXT SEVERAL HOURS WITH THE FOCUS GRADUALLY SHIFTING SOUTH INTO THE EVENING ALTHOUGH ISOLATED SHOWERS OR THUNDERSTORMS ARE POSSIBLE AT ANY TIME. A PROMINENT AREA OF CONVECTION UPSTREAM ACROSS IL/IN IS PROGGED TO WEAKEN AS IT MOVES SOUTHEAST AND SHOULD NOT IMPACT CENTRAL NC. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE UPPER 60S NORTHEAST TO LOWER 70S SOUTHWEST. -BLAES && .SHORT TERM /SUNDAY AND SUNDAY NIGHT /... AS OF 306 AM SATURDAY... SURFACE DRY AIR RIDGE EXTENDS SOUTHWARD INTO NC FROM A PARENT HIGH POSITIONED OVER NORTHERN MID ATLANTIC. THIS SURFACE RIDGE SUPPORTED ALOFT BY A BUILDING UPPER LEVEL RIDGE...STRETCHING FROM THE MID- LOWER MS VALLEY NEWD INTO NEW ENGLAND. NELY LOW LEVEL FLOW WILL ADVECT COOLER DRIER AIR INTO CENTRAL NC. THIS DRIER AIR WILL AID TO DIMINISH ANY RESIDUAL STRATOCU. LOW LEVEL THICKNESSES DROP TO VALUES 15-20M BELOW NORMAL FOR LATE AUGUST. THIS YIELDS MAX TEMPS OF NEAR 80 ACROSS THE FAR NORTH-NW TO LOW/MID 80S FAR SOUTH. MIN TEMPS SUNDAY NIGHT LOW-MD 60S. && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 250 PM SATURDAY... FOR MONDAY THROUGH MID-WEDNESDAY...LOOK FOR FAIR WEATHER WITH NEAR- TO SLIGHTLY-BELOW NORMAL TEMPS (HIGHS IN THE LOW-MID 80S AND LOWS IN THE LOW 60S) AS HIGH PRESSURE BUILDS IN TO THE CAROLINAS FROM THE NORTH EARLY IN THE WEEK AND REMAINS OVER OUR AREA THROUGH MID-WEEK. FORECAST SOUNDINGS SUGGEST PWAT WILL RANGE FROM 0.5-1.0 INCHES DURING THIS TIME...WHICH IS WELL BELOW THE 1.35 INCH NORM FOR LATE AUGUST. A LARGE DEGREE OF UNCERTAINTY EXISTS FOR THE SECOND HALF OF THE WEEK...AS THIS PART OF THE FORECAST IS LARGELY DEPENDENT ON WHAT HAPPENS WITH INVEST 96L. TRACK MODELS HAVE BEEN QUITE SCATTERED AND LITTLE AGREEMENT AMONG THE GEFS/NAEFS MEMBERS. HOWEVER...ITS WORTH NOTING THAT THE TREND IN THE OPERATIONAL GFS HAS BEEN DEVELOPMENT AND SLOW NORTHWARD MOVEMENT E OF FL DURING THE FIRST HALF OF THE WEEK...THEN MOVING NNE ALONG BUT REMAINING OFF THE CAROLINA COAST LATE IN THE WEEK. THE LATEST ECMWF IS SIMILAR WITH THE EVOLUTION OF THIS SYSTEM...BUT IS FASTER AND ITS TRACK REMAINS FURTHER OFF THE COAST...SHOWING THE LOW MOVING NE AWAY FROM THE EAST COAST ON THURSDAY. ESSENTIALLY BOTH OF THESE SOLUTIONS WOULD KEEP CENTRAL NC FAR ENOUGH WEST OF THE SYSTEM SUCH THAT OUR AREA WOULD REMAIN IN FAIR WEATHER DURING THE SECOND HALF OF THE WEEK. TAKING THAT SYSTEM OUT OF THE PICTURE...OUR NEXT CHANCE FOR WET WEATHER WOULD COME DURING THE WEEKEND ASSOCIATED WITH EITHER THE NEXT TROUGH IN THE WESTERLIES (PER GFS) OR INCREASING MOISTURE IN THE RETURN FLOW AROUND THE RIDGE (PER THE ECWMF). IN SUMMARY...LOTS OF UNCERTAINTY FOR THE SECOND HALF OF THE LONG TERM...SO WILL STICK CLOSE TO CLIMO FOR TEMPS AND PERHAPS A LITTLE LOWER THAN CLIMO FOR POPS DURING THIS TIME. && .AVIATION /18Z SATURDAY THROUGH WEDNESDAY/... AS OF 225 PM SATURDAY... AS OF 18Z...SOME MVFR CONDITIONS MAINLY ASSOCIATED WITH CIGS PERSIST ACROSS PARTS OF THE NORTHEAST PIEDMONT AND COASTAL PLAIN. ELSEWHERE VFR CONDITIONS WITH MULTIPLE LOW TO MID CLOUD LAYERS ARE OBSERVED. SCATTERED SHOWERS AND THUNDERSTORMS WILL BECOME MORE NUMEROUS AND MOVE SOUTHEAST THIS AFTERNOON AND EVENING ACROSS CENTRAL NC AS A COLD FRONT AND AN UPPER LEVEL DISTURBANCE TRIGGERS AND THEN MAINTAIN SCATTERED CONVECTION. INITIALLY THE PRECIPITATION WILL BE MOST WIDESPREAD THIS AFTERNOON ACROSS THE COASTAL PLAIN...MAINLY EAST OF THE KRWI AND KFAY TERMINALS. ANOTHER AREA OF SHOWERS AND THUNDERSTORMS WILL ROTATE AND PUSH SOUTH ACROSS THE NORTHERN PIEDMONT THIS AFTERNOON AND THEN GRADUALLY SHIFT SOUTH LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING. THE CONVECTION WILL TEND TO SHIFT SOUTH...WEAKEN AND DECREASE IN COVERAGE LATER THIS EVENING AND OVERNIGHT. EXPECT LOCAL REDUCTIONS TO MVR AND INTERMITTENTLY IFR CONDITIONS IN SHOWERS AND THUNDERSTORMS. PREVAILING CEILINGS WILL ALSO DECREASE OVERNIGHT AS COOLER AIR MOVES INTO THE REGION WITH PERIODS OF IFR CONDITIONS IN LOW CLOUDS AND SOME FOG LIKELY TOWARD DAYBREAK WITH HEATING AND AN INFLUX OF DRIER AIR FROM THE NORTHEAST...CEILINGS SHOULD LIFT A COUPLE OF HOURS AFTER DAYBREAK WITH VFR CONDITIONS PREVAILING BY LATE OR EARLY AFTERNOON. LOOKING FURTHER AHEAD...HIGH PRESSURE AT THE SURFACE AND ALOFT WILL EXTEND INTO THE REGION FOR THE LATE SUNDAY THROUGH WEDNESDAY PERIOD BRINGING A PERIOD OF GENERALLY FAIR WEATHER. EXCEPTIONS WOULD INCLUDE THE POTENTIAL FOR SOME DAYBREAK FOG ON MONDAY AND TUESDAY MORNINGS...ESPECIALLY ACROSS THE COASTAL PLAIN AND PERHAPS A SHOWER ACROSS THE EASTERN SECTIONS IN A PERSISTENT NORTHEAST FLOW. -BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES SHORT TERM...WSS LONG TERM...NP AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
250 PM EDT SAT AUG 23 2014 .SYNOPSIS...A COLD FRONT WILL MOVE SOUTH ACROSS SOUTHERN VIRGINIA AND NORTH CAROLINA THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD SOUTH INTO THE REGION WITH COOLER AND DRIER CONDITIONS EARLY NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... AS OF 1100 AM SATURDAY... LATEST SURFACE ANALYSIS REVEALS A COMPLEX PATTERN WITH THE BACK DOOR COLD FRONT NOW EXTENDING ACROSS NORTHEAST NC INTO SOUTHWESTERN VA AS WELL AS A SURFACE TROUGH EXTENDING ALONG THE NC/SC COAST WITH A WEAK SURFACE LOW CENTERED NEAR KILM. THE MAIN SURGE OF COLDER/DRIER AIR LAGS BEHIND THE FRONT AND IS LOCATED ACROSS EASTERN PA AND THE NORTHERN CHESAPEAKE BAY. A NORTHWEST FLOW DOMINATES THE MID AND UPPER AIR PATTERN ACROSS THE CAROLINAS WITH A STRENGTHENING NORTHERN STREAM JET POISED TO DROP INTO THE MID ATLANTIC THIS AFTERNOON...NOTE THE 105KT JET AT 200 HPA AT KIAD THIS MORNING. THE AIRMASS ACROSS THE REGION IS RATHER MOIST WITH PW VALUES OF 120-135% OF NORMAL AT KGSO/KMHX RESPECTIVELY. WITH THE ENHANCED FLOW ALOFT AND MULTIPLE MECHANISMS FOR LOCAL CONVERGENCE...NOT SURPRISED THAT HIGH RESOLUTION GUIDANCE SUGGESTS FAIRLY DECENT CONVECTIVE COVERAGE FOR THIS AFTERNOON. SHOWERS HAVE ALREADY BEGUN TO BLOSSOM IN SOUTHERN VA IN PROXIMITY TO THE SURFACE FRONT AND A DISTURBANCE IN THE NW FLOW ALOFT. OTHER CONVECTION IS BUBBLING UP IN THE COASTAL PLAIN AND COASTAL REGION NEAR THE SURFACE TROUGH. USED A BLEND OF HRRR AND RAP HOURLY PRECIP FIELDS TO GENERATE THE HOURLY POP/QPF/WX GRIDS THIS AFTERNOON. WHILE CONVECTIVE COVERAGE IS EXPECTED TO BE SOMEWHAT GENEROUS...ONLY A WEAKLY UNSTABLE AIRMASS WITH MLCAPE VALUES LESS THAN 1000 SHOULD MINIMIZE OVERAL INTENSITY. THE BEST FLOW ALOFT SHOULD REMAIN IN THE VA/MD/DE REGION WITH BULK SHEAR VALUES IN OUR CWA CLIMBING TO AROUND 2 5KTS. THE BIGGER THREAT WILL LIKELY BE ASSOCIATED WITH LOCALLY HEAVY RAIN WITH CELLS ORIENTED IN THE NW FLOW THAT REPEATEDLY MOVE OVER A GIVEN AREA. CLOUD COVER AND SCT CONVECTION SHOULD HOLD TEMPERATURES DOWN A BIT...ESPECIALLY IN THE NORTHEAST. A LITTLE BIT MORE SUNSHINE ACROSS THE SOUTHERN PIEDMONT AND SANDHILLS SHOULD ALLOW TEMPERATURES TO WARM TO AROUND OR JUST ABOVE 90. -BLAES MAIN AREA OF CONVECTION IS FORECAST TO BEGIN PUSHING TO THE SOUTH OF THE AREA BY THIS EVENING... WHILE THE LOW LEVEL FRONTAL ZONE BEGINS TO MOVE INTO THE AREA. THIS SHOULD YIELD A CONTINUED LOW END CHANCE OF AT LEAST SOME SHOWERS THOUGH. WITH A LOW LEVEL EAST TO NORTHEASTERLY FLOW TONIGHT... LOW STRATUS IS APT TO DEVELOP... WITH PATCHY LIGHT DRIZZLE EVEN. THE MAIN PUSH OF THE COOLER AIR SHOULD HOLD OFF UNTIL AFTER DAYBREAK SUNDAY. THUS... EXPECT LOW TEMPS WILL BE IN THE UPPER 60S TO LOWER 70S. SUNDAY: SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA ON SUNDAY... ALONG WITH DRIER AIR ALOFT. THIS WILL YIELD MUCH DRIER CONDITIONS ON SUNDAY... WITH SKIES BECOMING PARTLY SUNNY BY AFTERNOON. HIGH TEMPS WILL BE COOLER... AROUND 80 NORTHEAST TO MID 80S SOUTH/SOUTHWEST. CAN`T RULE OUT SOME LIGHT SHOWERS IN THE EAST TO EAST-NORTHEASTERLY LOW LEVEL FLOW IN THE MORNING TO EARLY AFTERNOON THOUGH. && .SHORT TERM /SUNDAY NIGHT AND MONDAY/... AS OF 306 AM SATURDAY... SURFACE DRY AIR RIDGE EXTENDS SOUTHWARD INTO NC FROM A PARENT HIGH POSITIONED OVER NORTHERN MID ATLANTIC. THIS SURFACE RIDGE SUPPORTED ALOFT BY A BUILDING UPPER LEVEL RIDGE...STRETCHING FROM THE MID- LOWER MS VALLEY NEWD INTO NEW ENGLAND. NELY LOW LEVEL FLOW WILL ADVECT COOLER DRIER AIR INTO CENTRAL NC. THIS DRIER AIR WILL AID TO DIMINISH ANY RESIDUAL STRATOCU. LOW LEVEL THICKNESSES DROP TO VALUES 15-20M BELOW NORMAL FOR LATE AUGUST. THIS YIELDS MAX TEMPS OF NEAR 80 ACROSS THE FAR NORTH-NW TO LOW/MID 80S FAR SOUTH. MIN TEMPS SUNDAY NIGHT LOW-MD 60S. && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 250 PM SATURDAY... FOR MONDAY THROUGH MID-WEDNESDAY...LOOK FOR FAIR WEATHER WITH NEAR- TO SLIGHTLY-BELOW NORMAL TEMPS (HIGHS IN THE LOW-MID 80S AND LOWS IN THE LOW 60S) AS HIGH PRESSURE BUILDS IN TO THE CAROLINAS FROM THE NORTH EARLY IN THE WEEK AND REMAINS OVER OUR AREA THROUGH MID-WEEK. FORECAST SOUNDINGS SUGGEST PWAT WILL RANGE FROM 0.5-1.0 INCHES DURING THIS TIME...WHICH IS WELL BELOW THE 1.35 INCH NORM FOR LATE AUGUST. A LARGE DEGREE OF UNCERTAINTY EXISTS FOR THE SECOND HALF OF THE WEEK...AS THIS PART OF THE FORECAST IS LARGELY DEPENDENT ON WHAT HAPPENS WITH INVEST 96L. TRACK MODELS HAVE BEEN QUITE SCATTERED AND LITTLE AGREEMENT AMONG THE GEFS/NAEFS MEMBERS. HOWEVER...ITS WORTH NOTING THAT THE TREND IN THE OPERATIONAL GFS HAS BEEN DEVELOPMENT AND SLOW NORTHWARD MOVEMENT E OF FL DURING THE FIRST HALF OF THE WEEK...THEN MOVING NNE ALONG BUT REMAINING OFF THE CAROLINA COAST LATE IN THE WEEK. THE LATEST ECMWF IS SIMILAR WITH THE EVOLUTION OF THIS SYSTEM...BUT IS FASTER AND ITS TRACK REMAINS FURTHER OFF THE COAST...SHOWING THE LOW MOVING NE AWAY FROM THE EAST COAST ON THURSDAY. ESSENTIALLY BOTH OF THESE SOLUTIONS WOULD KEEP CENTRAL NC FAR ENOUGH WEST OF THE SYSTEM SUCH THAT OUR AREA WOULD REMAIN IN FAIR WEATHER DURING THE SECOND HALF OF THE WEEK. TAKING THAT SYSTEM OUT OF THE PICTURE...OUR NEXT CHANCE FOR WET WEATHER WOULD COME DURING THE WEEKEND ASSOCIATED WITH EITHER THE NEXT TROUGH IN THE WESTERLIES (PER GFS) OR INCREASING MOISTURE IN THE RETURN FLOW AROUND THE RIDGE (PER THE ECWMF). IN SUMMARY...LOTS OF UNCERTAINTY FOR THE SECOND HALF OF THE LONG TERM...SO WILL STICK CLOSE TO CLIMO FOR TEMPS AND PERHAPS A LITTLE LOWER THAN CLIMO FOR POPS DURING THIS TIME. && .AVIATION /18Z SATURDAY THROUGH WEDNESDAY/... AS OF 225 PM SATURDAY... AS OF 18Z...SOME MVFR CONDITIONS MAINLY ASSOCIATED WITH CIGS PERSIST ACROSS PARTS OF THE NORTHEAST PIEDMONT AND COASTAL PLAIN. ELSEWHERE VFR CONDITIONS WITH MULTIPLE LOW TO MID CLOUD LAYERS ARE OBSERVED. SCATTERED SHOWERS AND THUNDERSTORMS WILL BECOME MORE NUMEROUS AND MOVE SOUTHEAST THIS AFTERNOON AND EVENING ACROSS CENTRAL NC AS A COLD FRONT AND AN UPPER LEVEL DISTURBANCE TRIGGERS AND THEN MAINTAIN SCATTERED CONVECTION. INITIALLY THE PRECIPITATION WILL BE MOST WIDESPREAD THIS AFTERNOON ACROSS THE COASTAL PLAIN...MAINLY EAST OF THE KRWI AND KFAY TERMINALS. ANOTHER AREA OF SHOWERS AND THUNDERSTORMS WILL ROTATE AND PUSH SOUTH ACROSS THE NORTHERN PIEDMONT THIS AFTERNOON AND THEN GRADUALLY SHIFT SOUTH LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING. THE CONVECTION WILL TEND TO SHIFT SOUTH...WEAKEN AND DECREASE IN COVERAGE LATER THIS EVENING AND OVERNIGHT. EXPECT LOCAL REDUCTIONS TO MVR AND INTERMITTENTLY IFR CONDITIONS IN SHOWERS AND THUNDERSTORMS. PREVAILING CEILINGS WILL ALSO DECREASE OVERNIGHT AS COOLER AIR MOVES INTO THE REGION WITH PERIODS OF IFR CONDITIONS IN LOW CLOUDS AND SOME FOG LIKELY TOWARD DAYBREAK WITH HEATING AND AN INFLUX OF DRIER AIR FROM THE NORTHEAST...CEILINGS SHOULD LIFT A COUPLE OF HOURS AFTER DAYBREAK WITH VFR CONDITIONS PREVAILING BY LATE OR EARLY AFTERNOON. LOOKING FURTHER AHEAD...HIGH PRESSURE AT THE SURFACE AND ALOFT WILL EXTEND INTO THE REGION FOR THE LATE SUNDAY THROUGH WEDNESDAY PERIOD BRINGING A PERIOD OF GENERALLY FAIR WEATHER. EXCEPTIONS WOULD INCLUDE THE POTENTIAL FOR SOME DAYBREAK FOG ON MONDAY AND TUESDAY MORNINGS...ESPECIALLY ACROSS THE COASTAL PLAIN AND PERHAPS A SHOWER ACROSS THE EASTERN SECTIONS IN A PERSISTENT NORTHEAST FLOW. -BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES/BSD SHORT TERM...WSS LONG TERM...NP AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
225 PM EDT SAT AUG 23 2014 .SYNOPSIS...A COLD FRONT WILL MOVE SOUTH ACROSS SOUTHERN VIRGINIA AND NORTH CAROLINA THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD SOUTH INTO THE REGION WITH COOLER AND DRIER CONDITIONS EARLY NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... AS OF 1100 AM SATURDAY... LATEST SURFACE ANALYSIS REVEALS A COMPLEX PATTERN WITH THE BACK DOOR COLD FRONT NOW EXTENDING ACROSS NORTHEAST NC INTO SOUTHWESTERN VA AS WELL AS A SURFACE TROUGH EXTENDING ALONG THE NC/SC COAST WITH A WEAK SURFACE LOW CENTERED NEAR KILM. THE MAIN SURGE OF COLDER/DRIER AIR LAGS BEHIND THE FRONT AND IS LOCATED ACROSS EASTERN PA AND THE NORTHERN CHESAPEAKE BAY. A NORTHWEST FLOW DOMINATES THE MID AND UPPER AIR PATTERN ACROSS THE CAROLINAS WITH A STRENGTHENING NORTHERN STREAM JET POISED TO DROP INTO THE MID ATLANTIC THIS AFTERNOON...NOTE THE 105KT JET AT 200 HPA AT KIAD THIS MORNING. THE AIRMASS ACROSS THE REGION IS RATHER MOIST WITH PW VALUES OF 120-135% OF NORMAL AT KGSO/KMHX RESPECTIVELY. WITH THE ENHANCED FLOW ALOFT AND MULTIPLE MECHANISMS FOR LOCAL CONVERGENCE...NOT SURPRISED THAT HIGH RESOLUTION GUIDANCE SUGGESTS FAIRLY DECENT CONVECTIVE COVERAGE FOR THIS AFTERNOON. SHOWERS HAVE ALREADY BEGUN TO BLOSSOM IN SOUTHERN VA IN PROXIMITY TO THE SURFACE FRONT AND A DISTURBANCE IN THE NW FLOW ALOFT. OTHER CONVECTION IS BUBBLING UP IN THE COASTAL PLAIN AND COASTAL REGION NEAR THE SURFACE TROUGH. USED A BLEND OF HRRR AND RAP HOURLY PRECIP FIELDS TO GENERATE THE HOURLY POP/QPF/WX GRIDS THIS AFTERNOON. WHILE CONVECTIVE COVERAGE IS EXPECTED TO BE SOMEWHAT GENEROUS...ONLY A WEAKLY UNSTABLE AIRMASS WITH MLCAPE VALUES LESS THAN 1000 SHOULD MINIMIZE OVERAL INTENSITY. THE BEST FLOW ALOFT SHOULD REMAIN IN THE VA/MD/DE REGION WITH BULK SHEAR VALUES IN OUR CWA CLIMBING TO AROUND 2 5KTS. THE BIGGER THREAT WILL LIKELY BE ASSOCIATED WITH LOCALLY HEAVY RAIN WITH CELLS ORIENTED IN THE NW FLOW THAT REPEATEDLY MOVE OVER A GIVEN AREA. CLOUD COVER AND SCT CONVECTION SHOULD HOLD TEMPERATURES DOWN A BIT...ESPECIALLY IN THE NORTHEAST. A LITTLE BIT MORE SUNSHINE ACROSS THE SOUTHERN PIEDMONT AND SANDHILLS SHOULD ALLOW TEMPERATURES TO WARM TO AROUND OR JUST ABOVE 90. -BLAES MAIN AREA OF CONVECTION IS FORECAST TO BEGIN PUSHING TO THE SOUTH OF THE AREA BY THIS EVENING... WHILE THE LOW LEVEL FRONTAL ZONE BEGINS TO MOVE INTO THE AREA. THIS SHOULD YIELD A CONTINUED LOW END CHANCE OF AT LEAST SOME SHOWERS THOUGH. WITH A LOW LEVEL EAST TO NORTHEASTERLY FLOW TONIGHT... LOW STRATUS IS APT TO DEVELOP... WITH PATCHY LIGHT DRIZZLE EVEN. THE MAIN PUSH OF THE COOLER AIR SHOULD HOLD OFF UNTIL AFTER DAYBREAK SUNDAY. THUS... EXPECT LOW TEMPS WILL BE IN THE UPPER 60S TO LOWER 70S. SUNDAY: SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA ON SUNDAY... ALONG WITH DRIER AIR ALOFT. THIS WILL YIELD MUCH DRIER CONDITIONS ON SUNDAY... WITH SKIES BECOMING PARTLY SUNNY BY AFTERNOON. HIGH TEMPS WILL BE COOLER... AROUND 80 NORTHEAST TO MID 80S SOUTH/SOUTHWEST. CAN`T RULE OUT SOME LIGHT SHOWERS IN THE EAST TO EAST-NORTHEASTERLY LOW LEVEL FLOW IN THE MORNING TO EARLY AFTERNOON THOUGH. && .SHORT TERM /SUNDAY NIGHT AND MONDAY/... AS OF 306 AM SATURDAY... SURFACE DRY AIR RIDGE EXTENDS SOUTHWARD INTO NC FROM A PARENT HIGH POSITIONED OVER NORTHERN MID ATLANTIC. THIS SURFACE RIDGE SUPPORTED ALOFT BY A BUILDING UPPER LEVEL RIDGE...STRETCHING FROM THE MID- LOWER MS VALLEY NEWD INTO NEW ENGLAND. NELY LOW LEVEL FLOW WILL ADVECT COOLER DRIER AIR INTO CENTRAL NC. THIS DRIER AIR WILL AID TO DIMINISH ANY RESIDUAL STRATOCU. LOW LEVEL THICKNESSES DROP TO VALUES 15-20M BELOW NORMAL FOR LATE AUGUST. THIS YIELDS MAX TEMPS OF NEAR 80 ACROSS THE FAR NORTH-NW TO LOW/MID 80S FAR SOUTH. MIN TEMPS SUNDAY NIGHT LOW-MD 60S. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 306 AM SATURDAY... MONDAY NIGHT THROUGH THURSDAY...TRANQUIL WEATHER PATTERN WILL CONTINUE. UPPER LEVEL RIDGE WILL REMAIN HIGHLY AMPLIFIED UNTIL LATE WEDNESDAY INTO THURSDAY AT WHICH TIME A S/W IN THE NORTHERN STREAM WILL BE EXITING THE NORTHERN PLAINS INTO THE GREAT LAKES. THE APPROACH OF THIS SYSTEM WILL WEAKEN/SUPPRESS THE UPPER RIDGE SOUTHWARD. ASSOCIATED SFC RIDGE WILL MAINTAIN A DRY WEATHER REGIME WITH MODERATING TEMPERATURES THROUGH THURSDAY. MAX TEMPS TUESDAY NEAR 80 NORTH TO LOWER 80S SOUTH WARM TO THE MID-UPPER 80S BY THURSDAY. MIN TEMPS ALSO GRADUALLY MODIFY...FROM THE UPPER 50S-LOWER 60S TUESDAY MORNING TO THE MID 60S THURSDAY MORNING. FORECAST CONFIDENCE WANES THURSDAY INTO FRIDAY AS GFS IS MUCH FASTER WITH THE APPROACH OF THE NORTHERN STREAM S/W TOWARD THE EAST COAST VERSUS THE SLOWER ECMWF. ALSO OF CONCERN IS THE EVENTUAL TRACK OF THE TROPICAL SYSTEM THAT IS EXPECTED TO TRACK PARALLEL BUT OFFSHORE OF THE SE U.S. COAST. LATEST MODEL GUIDANCE (MAINLY ECMWF) HAS SHIFTED A LITTLE MORE TO THE WEST...WITH MAJOR TIMING DIFFERENCES (ECMWF MUCH FASTER COMPARED TO THE GFS). WITH THE TROPICAL SYSTEM OFFSHORE AND A TROUGH IN THE VICINITY OF THE GREAT LAKES/MID MS VALLEY...WOULD EXPECT A NARROW RIDGE OVER THE CAROLINAS. UNTIL THE DIFFERENCES ARE RESOLVED...FAVOR A WARM AND MAINLY DRY FORECAST FOR THE END OF THE WORK WEEK. HAVE WARMED TEMPS INTO THE MID 80-AROUND 90 FOR MAX TEMPS FRIDAY WHILE DECREASED RAIN CHANCE TO SLIGHT CHANCE. && .AVIATION /18Z SATURDAY THROUGH WEDNESDAY/... AS OF 225 PM SATURDAY... AS OF 18Z...SOME MVFR CONDITIONS MAINLY ASSOCIATED WITH CIGS PERSIST ACROSS PARTS OF THE NORTHEAST PIEDMONT AND COASTAL PLAIN. ELSEWHERE VFR CONDITIONS WITH MULTIPLE LOW TO MID CLOUD LAYERS ARE OBSERVED. SCATTERED SHOWERS AND THUNDERSTORMS WILL BECOME MORE NUMEROUS AND MOVE SOUTHEAST THIS AFTERNOON AND EVENING ACROSS CENTRAL NC AS A COLD FRONT AND AN UPPER LEVEL DISTURBANCE TRIGGERS AND THEN MAINTAIN SCATTERED CONVECTION. INITIALLY THE PRECIPITATION WILL BE MOST WIDESPREAD THIS AFTERNOON ACROSS THE COASTAL PLAIN...MAINLY EAST OF THE KRWI AND KFAY TERMINALS. ANOTHER AREA OF SHOWERS AND THUNDERSTORMS WILL ROTATE AND PUSH SOUTH ACROSS THE NORTHERN PIEDMONT THIS AFTERNOON AND THEN GRADUALLY SHIFT SOUTH LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING. THE CONVECTION WILL TEND TO SHIFT SOUTH...WEAKEN AND DECREASE IN COVERAGE LATER THIS EVENING AND OVERNIGHT. EXPECT LOCAL REDUCTIONS TO MVR AND INTERMITTENTLY IFR CONDITIONS IN SHOWERS AND THUNDERSTORMS. PREVAILING CEILINGS WILL ALSO DECREASE OVERNIGHT AS COOLER AIR MOVES INTO THE REGION WITH PERIODS OF IFR CONDITIONS IN LOW CLOUDS AND SOME FOG LIKELY TOWARD DAYBREAK WITH HEATING AND AN INFLUX OF DRIER AIR FROM THE NORTHEAST...CEILINGS SHOULD LIFT A COUPLE OF HOURS AFTER DAYBREAK WITH VFR CONDITIONS PREVAILING BY LATE OR EARLY AFTERNOON. LOOKING FURTHER AHEAD...HIGH PRESSURE AT THE SURFACE AND ALOFT WILL EXTEND INTO THE REGION FOR THE LATE SUNDAY THROUGH WEDNESDAY PERIOD BRINGING A PERIOD OF GENERALLY FAIR WEATHER. EXCEPTIONS WOULD INCLUDE THE POTENTIAL FOR SOME DAYBREAK FOG ON MONDAY AND TUESDAY MORNINGS...ESPECIALLY ACROSS THE COASTAL PLAIN AND PERHAPS A SHOWER ACROSS THE EASTERN SECTIONS IN A PERSISTENT NORTHEAST FLOW. -BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES/BSD SHORT TERM...WSS LONG TERM...WSS AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS BISMARCK ND
259 PM CDT SAT AUG 23 2014 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 300 PM CDT SAT AUG 23 2014 THE MAIN FORECAST ISSUE IN THE SHORT TERM PERIOD WILL BE HEAVY RAIN LATE THIS AFTERNOON AND THIS EVENING. THEN ENDING ACROSS THE SOUTH LATE THIS EVENING BUT CONTINUING ACROSS THE NORTH INTO SUNDAY. LATEST RADAR ESTIMATES HAVE MATCHED UP WELL WITH OBSERVED REPORTS ACROSS SOUTHWEST NORTH DAKOTA. GENERALLY 1 TO 1.5 INCHES REPORTED SOUTH AND WEST OF A LINE FROM SELFRIDGE TO THEODORE ROOSEVELT NP. DID GET A REPORT FROM WFO BILLINGS OF CLOSER TO 5 INCHES NEAR BAKER MT. AS OF YET CALLS TO SPOTTERS AND BOWMAN EM HAVE RESULTED IN NO SIGNIFICANT FLOODING ISSUES. HOWEVER...WE HAVE ISSUED AN AREAL FLOOD ADVISORY SOUTH AND WEST OF LAKE SAKAKAWEA AND THE MISSOURI RIVER...TO COVER THE 1 TO 1.5 INCHES OF RAIN THAT HAS FALLEN IN ADDITION TO ADDITIONAL EXPECTED RAIN THROUGH THE AFTERNOON AND TONIGHT. REGARDING THE CURRENT FLOOD WATCH AND POTENTIAL OF SEVERE WEATHER... WILL LET THE WATCH CONTINUE. HEAVIEST RAIN HAS FALLEN ACROSS THE MOST SATURATED SOILS IN THE SOUTHWEST. THE HEAVIEST ADDITIONAL ACCUMULATIONS TONIGHT SHOULD BE CENTERED ACROSS THE NORTH CENTRAL AND NORTHWEST. IF WE HAD TO PARE IT DOWN...WOULD PROBABLY REMOVE WELLS SOUTH THROUGH MCINTOSH. HOWEVER...THERE IS STILL A THREAT OF AFTERNOON AND EVENING CONVECTION HERE AS THE SURFACE LOW LIFTS INTO NORTH DAKOTA. THUS WILL CONTINUE AS IS FOR NOW. THE LATEST HRRR STILL DEVELOPS SCATTERED CONVECTION IN THIS AREA THIS EVENING. HOWEVER THE STRONGEST CONVECTION IS NOW BEING PLACED TO THE SOUTH OF THE CWA. WITH OUR EAST TO NORTHEAST FLOW AND COOLER TEMPERATURES OVER NORTH DAKOTA THIS SEEMS REASONABLE...BUT WITH THE SURFACE LOW LIFTING INTO CENTRAL NORTH DAKOTA THINK OUR SOUTHEAST CWA WILL BE IN A FAVORED LOCATION FOR ABUNDANT LOW LEVEL HELICITY THUS WILL CONTINUE A MENTION OF SEVERE OVER THE SOUTHEAST CWA. WE DRY OUT FROM SOUTH TO NORTH LATE THIS EVENING THROUGH SUNDAY. HIGHEST POPS WILL REMAIN OVER THE NORTHWEST AND FAR NORTH CENTRAL. WITH THE UPPER LEVEL SLOW LIFTING THROUGH EASTERN MONTANA INTO NORTHWEST ND...THERE SHOULD STILL BE ENOUGH MID TO UPPER LEVEL FORCING TO MENTION ISOLATED THUNDER THROUGH THE DAY WHEREVER WE HAVE A MENTION OF SHOWERS. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 300 PM CDT SAT AUG 23 2014 SUNDAY EVENING THE UPPER LEVEL LOW IS PROGGED TO BE AT THE BORDER OF MONTANA AND NORTH DAKOTA...WITH THE SURFACE LOW ALONG THE NORTH DAKOTA/CANADIAN/MINNESOTA BORDER. THE ELONGATED SURFACE LOW/FRONT COMBINED WITH THE UPPER LOW TO THE WEST WILL KEEP HIGH CHANCES OF SHOWERS IN THE NORTHWEST/NORTH CENTRAL SUNDAY NIGHT. THE SYSTEM LIFTS NORTHEASTWARD SUNDAY NIGHT AND INTO MONDAY...WITH COLD ADVECTION IN ITS WAKE. LOOKING AT LOWS SUNDAY NIGHT IN THE 40S WEST TO LOWER 50S IN THE JAMES VALLEY. MOSTLY CLOUDY SKIES NORTH MONDAY WILL KEEP MAXIMUM TEMPERATURES CONFINED TO THE UPPER 50S WITH 60S SOUTH. BY TUESDAY MORNING THE SURFACE HIGH SETTLES OVER NORTH DAKOTA...AND LOW TEMPERATURES SHOULD BE IN THE 40S ACROSS WESTERN AND CENTRAL NORTH DAKOTA. DURING THE DAY TUESDAY THROUGH WEDNESDAY THE TRAILING UPPER LEVEL TROUGH MOVES EAST ACROSS THE NORTHERN PLAINS...WITH ISOLATED TO SCATTERED SHOWERS POSSIBLE. MINOR UPPER LEVEL RIDGING OCCURS WEDNESDAY NIGHT THROUGH FRIDAY. THE APPROACH OF ANOTHER ROCKIES TROUGH TOWARDS NEXT WEEKEND MAY BE THE NEXT CHANCE OF SHOWERS AND THUNDERSTORMS. A SLOW WARMING TREND WITH HIGHS TUESDAY IN THE 60S WARMING TO THE 80S BY FRIDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 300 PM CDT SAT AUG 23 2014 MAINLY IFR CEILINGS EXPECTED THROUGH THE FORECAST PERIOD WITH OCCASIONAL MVFR VISIBILITIES IN HEAVIER SHOWERS. COULD SEE PERIODS OF MVFR CEILINGS THIS AFTERNOON...THEN AGAIN LATE SUNDAY MORNING AS THE STRONG LOW LIFTS OUT OF THE AREA. OTHERWISE EXPECT IFR TO OCCASIONALLY LIFR. WINDS WILL BE VARIABLE WITH THE SURFACE LOW EXPECTED TO LIFT THROUGH WESTERN NORTH DAKOTA...BUT MAINLY EAST TO SOUTHEAST TODAY AND THIS EVENING...SHIFTING WESTERLY FROM SOUTH TO NORTH ON SUNDAY. SPEEDS GENERALLY 10 TO 25 KNOTS. && .HYDROLOGY... ISSUED AT 300 PM CDT SAT AUG 23 2014 MODERATE TO HEAVY RAINS OVER THE PAST WEEK HAVE KEPT SOIL MOISTURE ABNORMALLY HIGH ACROSS WESTERN AND CENTRAL NORTH DAKOTA. RAINFALL THAT OCCURRED TODAY...ALONG WITH THE EXPECTED RAINFALL INTO TONIGHT MAY LIKELY LEAD TO SOME OVERLAND FLOODING...ALONG WITH INCREASED FLOWS INTO CREEKS...STREAMS...AND RIVERS. ALONG WITH THE FLOOD WATCH THAT WAS ISSUED ON FRIDAY FOR TODAY THROUGH SUNDAY...HAVE ALSO ISSUED AN AREAL FLOOD ADVISORY FOR THE AREA SOUTH AND WEST OF THE MISSOURI RIVER. RADAR ESTIMATES WERE IN AGREEMENT WITH SOME RAINFALL REPORTS OF 1 TO 1.5 INCHES OF RAINFALL SO FAR TODAY. IN ADDITION...WHILE THERE IS NO REASONABLE EXPECTATION OF MAJOR RIVER FLOODING...AT A MINIMUM THERE WILL BE SIGNIFICANT WITHIN BANK RISES...AND MINOR RIVER FLOODING CANNOT BE RULED OUT. .BIS WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR NDZ001>005-009>013- 017>023-031>036-040>047-050. && $$ SHORT TERM...TWH LONG TERM...JV AVIATION...TWH
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
220 PM EDT SAT AUG 23 2014 .SYNOPSIS... UPPER RIDGING WILL SLOWLY BUILD OVER THE REGION BY SUNDAY...BRINGING AN END TO THE RECENT SIEGE OF SHOWER AND THUNDERSTORM ACTIVITY. THE UPPER RIDGE WILL DOMINATE THE WEATHER PATTERN OVER THE NORTHEAST UNITED STATES AND SOUTHEASTERN CANADA DURING THE EARLY AND MIDDLE PART OF THE UPCOMING WEEK...WITH THE NEXT CHANCE OF RAINFALL NOT ARRIVING UNTIL LATE WEDNESDAY OR THURSDAY FROM AN APPROACHING MIDWESTERN FRONTAL SYSTEM. && .NEAR TERM /THROUGH TONIGHT/... SATELLITE SHOWS SOME BREAKS IN THE OVERCAST OVER THE FAR WESTERN PERIPHERY OF MY FCST AREA...WHICH IS WHERE WE ARE MANAGING TO DEVELOP SOME CAPE. WITH THE PERSISTENT LOW LEVEL CONVERGENCE AND EASTERLY UPSLOPE FLOW...SCATTERED CONVECTION IS BEGINNING TO POP IN THIS SLIGHTLY ELEVATED INSTABILITY FROM MCKEAN COUNTY DOWN THROUGH WESTERN CAMBRIA AND SOMERSET COUNTIES. LATEST HRRR DOESN`T SHOW ANY PARTICULAR AREA FAVORING ANY KIND OF REAL ORGANIZATION OF THE CONVECTION INTO THE LATE AFTERNOON HOURS...BUT WE HAVE SEEN SOME OF THE SHOWERS BE VERY EFFICIENT...PRODUCING LOCALLY HEAVY RAINS. THE PERSISTENT...AND ANOMALOUS SFC-850 MB EAST TO SERLY FLOW AND HIGH PWAT AIR WILL AT LEAST MAINTAIN WIDESPREAD/THICK CLOUD COVER AND UNSEASONABLY COOL TEMPS...EXCEPT OVER THOSE FAR WESTERN AREAS WHERE A BIT OF SUNSHINE WILL HELP PUSH TEMPS INTO THE LOWER TO MID 70S. THE LARGE SCALE PATTERN IS ADVERTISED TO CHANGE ONLY SLOWLY OVER THE NEXT 12-18 HOURS...WITH DRIER AIR EVENTUALLY SLIDING DOWN OUT OF THE NORTH AND SHOVING THE HIGHER MOISTURE BACK TO OUR SOUTH AND WEST. MOSTLY CLOUDY SKIES WILL PERSIST FOR MUCH OR PERHAPS ALL OF THE OVERNIGHT WITH A CHANCE OF LIGHT RAIN OR DRIZZLE MAINLY BEFORE MIDNIGHT...AND ACROSS THE SW CORNER OF THE CWA. ANY CLEARING LATE TONIGHT WILL COMBINE WITH THE MOIST GROUND AND LIGHT WIND TO PRODUCE AREAS OF FOG...THAT WILL BECOME LOCALLY DENSE AFTER MIDNIGHT. LOW TEMPS EARLY SUNDAY WILL RANGE FROM THE MID 50S ACROSS THE NORTH...TO AROUND 60F IN THE SOUTHERN VALLEYS. && .SHORT TERM /SUNDAY/... DRIER AIR WILL SETTLE OVER THE AREA SUNDAY BRINGING A MUCH ANTICIPATED BREAK FROM THE RECENT ALMOST DAILY ASSAULT OF SHOWERS AND THUNDERSTORMS. CANNOT RULE OUT A LINGERING SHOWER OR DRIZZLE OVER THE SWRN AREAS IN THE AREA OF BEST LOW LEVEL UPSLOPE FLOW...BUT OVERALL TREND WILL BE FOR MOST LOCATIONS TO SEE A RAIN-FREE DAY FOR A CHANGE. AREAS OF MORNING CLOUDS AND PERHAPS SOME PATCHY LIGHT DRIZZLE... WILL TRANSITION INTO INCREASINGLY SUNNY SKIES DURING THE MIDDAY AND AFTERNOON HOURS SUNDAY. TEMPS SUNDAY WILL REBOUND NICELY FROM SATURDAY/S CHILL WITH AFTERNOON HIGHS IN THE MID 70S ACROSS THE MTNS...AND AROUND 80F THROUGHOUT THE SUSQ VALLEY. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... MUCH OF THE EXTENDED WILL FEATURE A BIG RIDGE DOMINATING THE PATTERN OVER THE EASTERN AND NORTHEASTERN US. FAIR WEATHER WILL DEVELOP ALONG WITH WARMING TEMPERATURES AS THE RIDGE ESTABLISHES ITSELF AND MAINTAINS ITS HOLD UNTIL AT LEAST LATER WEDNESDAY-THURSDAY WHEN THE NEXT FRONTAL SYSTEM IS ADVERTISED TO APPROACH. 500 HEIGHTS IN EXCESS OF 5900M ARE FCST TO POKE INTO PA BY LATER MONDAY AND CONTINUE INTO WED. THIS WILL ASSURE THE FIRST DAYS OF THE NEW SCHOOL YEAR WILL BE WARM AND FAIRLY UNCOMFORTABLE. THE OPERATIONAL GFS AND ECMWF KEEP US DRY THROUGH AT LEAST LATER WEDNESDAY WHILE THE GEFS CONTINUES THE TREND TOWARD BEING MORE PESSIMISTIC...BRINGING MEASURABLE RAINS EAST QUICKER UNDER A FLATTER UPPER FLOW. IT SEEMS THE RESOLUTION OF THE TROPICAL SYSTEM IS PLAYING A ROLE IN THE EXTENDED FORECASTS FOR THE GFS/GEFS VS THE ECMWF. THE ECMWF HUSTLES A TROPICAL STORM OFF THE EAST COAST FASTER THAN THE GFS...WHICH ALLOWS IT TO REBUILD THE EASTERN RIDGE QUICKER. STILL TOO MUCH UNCERTAINTY TO LATCH ONTO ANY SOLID SOLUTION. WILL KEEP THE CURRENT BLAND CHANCE OF SHOWERS STARTING WEDNESDAY NIGHT LASTING INTO AT LEAST THURSDAY NIGHT. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... STILL HAVE LOW CIGS ACROSS THE AREA AND NOT MUCH CHANGES EXPECTED THIS AFTERNOON. WIDELY SCATTERED SHOWER ACTIVITY ACROSS THE ENTIRE AREA. FOG AND CEILING RESTRICTIONS WILL AGAIN OVERSPREAD THE AREA TONIGHT. IN THE LONGER RUN...HIGH PRESSURE WILL SLOWLY BUILD INTO THE NORTHEAST ON SUNDAY CONTINUING INTO MID WEEK. FRONT APPROACHING LATER WEDNESDAY AND THURSDAY MAY BRING THE NEXT ROUND OF SHRA/TSRA. OUTLOOK... SUN...LOW CIGS AND FOG EARLY...THEN VFR MON- WED...MORNING RESTRICTIONS FROM FOG POSSIBLE...OTHERWISE VFR. THU...RESTRICTIONS POSSIBLE WITH THUNDERSTORMS AND A COLD FRONT. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE NEAR TERM...LA CORTE SHORT TERM...LA CORTE LONG TERM...LA CORTE AVIATION...JUNG/ROSS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
309 PM CDT SAT AUG 23 2014 .SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT) ISSUED AT 309 PM CDT SAT AUG 23 2014 SHORT TERM MAIN CONCERN IS INCREASING HEAT SUNDAY. WATER VAPOR/RAP 500MB ANALYSIS THIS AFTERNOON HAVE A MID-LEVEL SHORTWAVE AND ASSOCIATED BAND OF SHOWERS/THUNDERSTORMS PER RADAR MOSAIC ROTATING THROUGH SOUTHWEST WI/NORTHERN IL. CLOUD COVER AND SCATTERED PRECIPITATION KEEP TEMPERATURES IN THE 70S...BUT WITH VERY HUMID AIRMASS IN PLACE...FEELING MORE LIKE THE 80S. FOR TONIGHT...LOW PRESSURE MOVING NORTHEAST OUT OF THE CENTRAL HIGH PLAINS INTO THE NORTHERN PLAINS WILL DRAG A WARM FRONT NORTHWARD THROUGH THE REGION. STILL A CHANCE OF A FEW SHOWERS AND THUNDERSTORMS ALONG THE FRONTAL BOUNDARY...MAINLY ALONG/NORTHEAST OF I-94 AS EASTERN FLANK OF 850MB MOISTURE TRANSPORT IMPINGES UPON IT. OTHERWISE...WILL LIKELY SEE SOME STRATUS DEVELOPMENT TONIGHT IN MOIST SOUTHERLY FLOW. ANY DENSE FOG POTENTIAL LOOKS MINIMAL AT THIS POINT GIVEN STRENGTHENING SOUTHERLY FLOW TO KEEP THE LOWER BOUNDARY LAYER SOMEWHAT MIXED. LOOK FOR LOWS TONIGHT IN THE MID/UPPER 60S ACROSS CENTRAL WI...AND LOWER 70S ELSEWHERE. LOOKS LIKE THE HEAT IS ON FOR SUNDAY AS WE WILL BE IN THE WARM/CAPPED WARM SECTOR OF THE NORTHER PLAINS LOW. NAM STILL SHOWING 925MB TEMPERATURES IN THE 28-30C RANGE WEST OF THE MISSISSIPPI AND 25- 28C RANGE ACROSS THE EAST. AFTER SOME INITIAL MORNING STRATUS...EXPECTING SUNSHINE AND THIS HOT SOUTHERLY FLOW TO PUSH HIGHS INTO THE MID/UPPER 80S ACROSS CENTRAL WI...AND IN THE LOWER 90S IN THE WI RIVER VALLEY AND AREAS ALONG AND WEST OF THE MISSISSIPPI RIVER. WITH DEW POINTS IN THE 70-75 DEGREE RANGE...LOOKING AT HEAT INDICES IN THE 95 TO 105 DEGREE RANGE. AFTER COLLABORATION WITH SURROUNDING OFFICES AND CRITERIA CONSIDERATIONS...WILL HOLD OFF ON HEAT HEADLINE FOR NOW AND WILL CONTINUE TO CONVEY CONCERN VIA OUR HAZARDOUS WEATHER OUTLOOK AND WEATHER STORY/GRAPHIC PRODUCTS. A COLD FRONT WILL THEN PUSH INTO THE AREA SUNDAY NIGHT FOR THE LIKELIHOOD OF THUNDERSTORMS. CANNOT RULE OUT A SEVERE CHANCE GIVEN HIGHER CAPE ENVIRONMENT AND SUFFICIENT 0-3KM BULK SHEAR IN THE 20- 30KT RANGE. WILL HAVE TO KEEP A CLOSE EYE ON THIS. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 309 PM CDT SAT AUG 23 2014 MEDIUM RANGE MODELS REMAIN IN PRETTY GOOD AGREEMENT WITH FRONTAL BOUNDARY LINGERING ACROSS THE REGION THROUGH AT LEAST THURSDAY. MODELS SHOW SEVERAL MID-LEVEL IMPULSES WORKING ON THIS FRONTAL BOUNDARY FOR CONTINUED SHOWER/THUNDERSTORM CHANCES. WITH PRECIPITABLE WATER VALUES REMAINING IN THE 1.5-2 INCH RANGE...WILL HAVE TO KEEP AN EYE ON REPETITIVE CONVECTION POTENTIAL/POSSIBLE LOCALIZED FLOODING. OTHERWISE...WITH CLOUD COVER AND GOOD CHANCES OF SHOWERS AND STORMS...PLAN ON HIGH TEMPERATURES STARING OFF IN THE 80-90 DEGREE RANGE MONDAY...COOLING INTO THE LOWER/MIDDLE 70S BY THURSDAY. SOME TIMING DIFFERENCES THEN ARISE BETWEEN THE GFS AND ECMWF FOR FRIDAY AND SATURDAY. BOTH MODELS MOVE A MORE VIGOROUS MID-LEVEL TROUGH THE REGION. GFS IS MUCH FASTER/PROGRESSIVE WITH THIS FEATURE COMPERED TO THE ECMWF. AT THIS POINT...WILL TAKE A CONSENSUS APPROACH WHICH YIELDS SMALLER-END SHOWER/THUNDERSTORM CHANCES WITH HIGHS IN THE 70S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1201 PM CDT SAT AUG 23 2014 THE SHOWERS AND STORMS CONTINUE TO ADVANCE NORTHEAST ACROSS THE AREA BUT ARE NOW SHOWING A DIMINISHING TREND. EXPECT THAT THESE WILL BE PAST KRST BY 18Z BUT WILL LINGER INTO THE EARLY AFTERNOON WITH SOME MVFR CONDITIONS AT KLSE. ONCE THESE MOVE THROUGH...EXPECT THAT BOTH SITES WILL HAVE VFR CONDITIONS AS A WARM FRONT APPROACHES AND THEN MOVES THROUGH SWINGING THE WINDS AROUND TO THE SOUTHEAST. HOWEVER...NO DECREASE IN THE LOW LEVEL HUMIDITY LEVELS WILL OCCUR WHICH SHOULD PRESENT THE POSSIBILITY OF IFR CEILINGS WITH LOW STRATUS AGAIN TONIGHT. THE FORECAST SOUNDINGS FROM THE 23.12Z NAM AND 23.15Z RAP BOTH INDICATING THE STRATUS SHOULD FORM AND HAVE INCLUDED IT IN BOTH FORECASTS. NOT OVERLY CONCERNED ABOUT FOG FOR TONIGHT AS BOTH THE SURFACE WINDS AND WINDS JUST ABOVE THE SURFACE SHOULD BE TOO STRONG WITH TOO MIXING TO ALLOW IT TO FORM. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM....DAS AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1201 PM CDT SAT AUG 23 2014 .UPDATE... ISSUED AT 954 AM CDT SAT AUG 23 2014 BASED ON THE 23.12Z RAP...NOT REALLY EXPECTING THE COMPLEX OF SHOWERS AND STORMS TO DISSIPATE ANY TIME SOON. A SHORT WAVE TROUGH WILL CONTINUE TO SLOWLY MOVE NORTHEAST THROUGH THE AREA PROVIDING WEAK TO MODERATE PV ADVECTION IN THE 500-300 MB LAYER. IN THE LOW LEVELS...THE WARM FRONT WILL BE ADVANCING TOWARD THE AREA WITH WEAK FRONTOGENESIS IN THE 1000-850 MB LAYER THROUGH THE DAY. WARM AIR ADVECTION OVER THIS FRONT WILL PROVIDE 4 TO 6 UBAR/S OF UP GLIDE ON THE 310K ISENTROPIC SURFACE. THE MOISTURE TRANSPORT AT 850 MB SHOULD CONTINUE TO BE INTO AND OVER THE WARM FRONT. BASED ON ALL THIS...HAVE INCREASED THE RAIN CHANCES TO 80 PERCENT OR HIGHER FOR THE REMAINDER OF THE MORNING WEST OF THE MISSISSIPPI RIVER AND THEN ALLOWED FOR A SLOW WEAKENING TREND WHILE SPREADING THE RAIN CHANCES ACROSS MOST OF WISCONSIN DURING THE AFTERNOON. WILL LET THE DENSE FOG ADVISORY EXPIRE AS SCHEDULED AT 10 AM. MOST OF THE VISIBILITY HAS IMPROVED TO 2 MILES OR BETTER AND THE INCOMING RAIN SHOULD ALSO HELP TO CLEAN THE ATMOSPHERE UP A LITTLE BIT. UPDATE ISSUED AT 737 AM CDT SAT AUG 23 2014 A SHORT WAVE TROUGH CONTINUES TO MOVE NORTHEAST TOWARD THE FORECAST AREA THIS MORNING. THE HRRR SEEMS TO HAVE THE BEST HANDLE ON ITS PRECIPITATION...SO TRENDED THE FORECAST TOWARD IT. AS THE SYSTEM MOVES INTO OUR AREA THIS EXPECT TO SEE A GRADUAL SPLIT AS THE 850 TO 700 MB MOISTURE TRANSPORT BREAKS APART AND ONE PART GOES ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN...AND THE OTHER PIECE MOVES TO THE WEST OF OUR AREA. SO EXPECT THE AREA WHICH MOVES INTO SOUTHEAST MINNESOTA TO DISSPATE. MEANWHILE THE BETTER CHANCES OF PRECIPITATION WILL BE SOUTH OF INTERSTATE 90 AS THAT JET VEERS THROUGH THAT AREA. THERE MAY BE A REMNANT MCV THAT KEEPS SOME PRECIPITATION ACROSS WESTERN WISCONSIN THIS AFTERNOON. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 330 AM CDT SAT AUG 23 2014 SFC BOUNDARY LIES...MORE OR LESS...WEST EAST ACROSS SOUTHERN IA INTO CENTRAL ILL EARLY THIS MORNING. AN UPPER LEVEL TROUGH WILL LIFT NORTHEAST ACROSS THE NORTHERN PLAINS TODAY...AND SHOULD HELP GIVE THIS BOUNDARY A SHOVE NORTH. MEANWHILE...THERE ARE SUGGESTIONS IN THE MESO MODELS THAT AN MCV ASSOCIATED WITH THE CURRENT CONVECTION OVER NEB WOULD TAKE NORTHEAST TRACK TODAY...AND COULD SERVE AS A FOCUS FOR SHOWER/STORMS DEVELOP AS IT AND THE BOUNDARY SLIDE NORTH/NORTHEAST ACROSS THE REGION. HEAT AND HUMIDITY WILL ROUND OUT THE WEEKEND...AND HEAT ADVISORIES LOOK LIKELY FOR PORTIONS OF THE REGION. 850 MB SREF TEMP ANOMALIES AROUND +1.5 FOR SUNDAY WHILE 950 MB TEMPS ARE EXPECTED TO WARM TO 26- 28 C. HIGHS SHOULD REACH 90 ACROSS MUCH OF THE FORECAST AREA. ADD IN DEW POINTS IN THE LOWER 70S AND AFTERNOON HEAT INDICES SHOULD REACH 100 FOR A LARGE PORTION OF THE FORECAST AREA. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 330 AM CDT SAT AUG 23 2014 MODELS IN PRETTY GOOD AGREEMENT WITH THE OVERALL PATTERN THROUGH THE MIDDLE PART OF THE NEW WORK WEEK. SOLUTIONS SUGGEST AN UPPER LEVEL SHORTWAVE WILL TRACK OUT OF THE CENTRAL ROCKIES...ACROSS THE NORTHERN PLAINS AND INTO SOUTHERN CANADA SUNDAY NIGHT. ITS ASSOCIATED SFC COLD FRONT WILL DRAG ACROSS THE REGION LATE SUNDAY NIGHT INTO MONDAY...WITH THE SOUTHERN EXTENT LIKELY LINGERING IN A SOUTHWEST-NORTHEAST ORIENTATION OVER THE REGION. RIPPLES IN THE UPPER LEVEL FLOW WILL KICK OUT OF THE MEAN TROUGH...AND WORK ON THIS BOUNDARY MON-TUE. THIS NEXT TROUGH THEN SLIDES ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WED NIGHT/THU...CONTINUING TO WORK ON THAT SFC BOUNDARY...BUT ALSO PUSHING IT EAST/SOUTHEAST AS THE SYSTEM EXITS INTO THE EASTERN GREAT LAKES ON THU NIGHT. THERE ARE SOME DISCREPANCIES IN THE MODELS WITH PLACEMENT...TIMING AND STRENGTH OF THIS TROUGH...BUT THE TRENDS ARE SIMILAR AND ALL POINT TO SEVERAL DAYS WITH RAIN CHANCES. NOT OVERLY STRONG...BUT FAIRLY PERSISTENT FETCH OF 850 MB MOISTURE TRANSPORT INTO THE REGION FOR THE EARLY PART OF THE UPCOMING WEEK. WARM CLOUD DEPTHS CONTINUE TO HOVER NEAR 4 KFT WHILE PWS RANGE FROM 1.5 TO 1.75 INCHES. SO...HEAVY RAIN WOULD BE LIKELY WITH ANY THUNDERSTORMS...ESPECIALLY THE STRONGER ONES. AS FOR SEVERE POTENTIAL...AFTERNOON SBCAPES PROGGED FROM 2000-3000 J/KG PER THE GFS INTO WED...MOSTLY AROUND AND SOUTH OF THE SFC BOUNDARY. HOWEVER...WITH LOW/MID LEVEL WARMING PERSISTING...AND 700 MB TEMPS AROUND 10 C...THERE WILL BE A CAP TO DEAL WITH...AND SOME OF THIS LOW LEVEL INSTABILITY WILL NOT BE REALIZED. BUFKIT SOUNDINGS INDICATE THIS TOO. THE DEEPER...STRONGER SHEAR IS EXPECTED TO BE WELL INTO THE COLD AIR NORTH OF THE BOUNDARY...DISPLACED FROM THE STRONGER INSTABILITY. THERE IS SOME OVERLAP...SO SOME ENHANCED UPDRAFTS COULD BE SUPPORTED. OVERALL...NOT SURE THERE IS A TIME PERIOD THAT STANDS OUT FOR AN ORGANIZED SEVERE THREAT AT THIS TIME. THERE CERTAINLY COULD BE SOME SEVERE TO MARGINAL SEVERE STORMS...PERHAPS MORE PULSEY IN NATURE. MUCH DEPENDS ON BOUNDARY/SHORTWAVE INTERACTION AND TIME OF DAY. LOOK FOR UPDATES IN THE HWO FOR THE LATEST THOUGHTS ON THE DAY TO DAY SEVERE POTENTIAL. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1201 PM CDT SAT AUG 23 2014 THE SHOWERS AND STORMS CONTINUE TO ADVANCE NORTHEAST ACROSS THE AREA BUT ARE NOW SHOWING A DIMINISHING TREND. EXPECT THAT THESE WILL BE PAST KRST BY 18Z BUT WILL LINGER INTO THE EARLY AFTERNOON WITH SOME MVFR CONDITIONS AT KLSE. ONCE THESE MOVE THROUGH...EXPECT THAT BOTH SITES WILL HAVE VFR CONDITIONS AS A WARM FRONT APPROACHES AND THEN MOVES THROUGH SWINGING THE WINDS AROUND TO THE SOUTHEAST. HOWEVER...NO DECREASE IN THE LOW LEVEL HUMIDITY LEVELS WILL OCCUR WHICH SHOULD PRESENT THE POSSIBILITY OF IFR CEILINGS WITH LOW STRATUS AGAIN TONIGHT. THE FORECAST SOUNDINGS FROM THE 23.12Z NAM AND 23.15Z RAP BOTH INDICATING THE STRATUS SHOULD FORM AND HAVE INCLUDED IT IN BOTH FORECASTS. NOT OVERLY CONCERNED ABOUT FOG FOR TONIGHT AS BOTH THE SURFACE WINDS AND WINDS JUST ABOVE THE SURFACE SHOULD BE TOO STRONG WITH TOO MIXING TO ALLOW IT TO FORM. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE...04 SHORT TERM...RIECK LONG TERM....RIECK AVIATION...04