Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/19/13


AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1011 PM MDT MON SEP 16 2013 .UPDATE... ISSUED AT 901 PM MDT MON SEP 16 2013 A FEW SHOWERS AND THUNDERSTORMS CONTINUE TO PERSIST OVER THE UINTA MTNS IN NORTHEAST UTAH THIS EVENING...AND ADJUSTED THE GRIDDED FORECAST ACCORDINGLY. A FAIR AMOUNT OF LIGHTNING INDICATED WITH SOME OF THESE THUNDERSTORMS. ELSEWHERE ACROSS THE FORECAST AREA...SHOWERS HAVE DIED DOWN WITH THE LOSS OF SOLAR HEATING. PRECIPITABLE WATER OF 0.64 INCH ON THIS EVENING/S GJT SOUNDING WAS DOWN CONSIDERABLY FROM THE 0.94 INCH MEASURED THIS MORNING. A QUICK LOOK AT THE 00Z NAM AND 00Z RAP MODELS SHOW A WEAK DISTURBANCE CROSSING THE SOUTH LATER TONIGHT...AND THE CURRENT FORECAST MAINTAINS MENTION OF AN ISOLATED SHOWER OR STORM POSSIBLE OVER THE SAN JUAN MTNS AFTER MIDNIGHT. && .SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT) ISSUED AT 356 PM MDT MON SEP 16 2013 LOCAL PROFILERS AND WATER VAPOR IMAGERY SHOWING THE TROF THAT HAS BEEN LINGERING IN THE WEST FINALLY PUSHING ONTO THE PLAINS THIS AFTERNOON. WEAKER UPSTREAM WAVE IS MOVING IN BEHIND A TRANSITORY RIDGE IN NORTHERN UTAH AND PROVIDING A BIT MORE FOCUS FOR STORMS IN OUR WESTERN CWA...WITH HEATING DRIVING ISOLATED CONVECTION ELSEWHERE. A DIP IN THE WESTERLIES IS MOVING ONTO THE WEST COAST THIS AFTERNOON WHICH WILL BE DRIVING A SERIES OF STRONGER OPEN OUT OF THE EASTERN PACIFIC BEGINNING TONIGHT. SOUNDINGS SHOW SOME DRIER AIR MOVING INTO THE LOWER LAYERS OF THE PROFILE BUT MOISTURE STILL HANGING AROUND 600-500MB KEEPING PWATS ABOVE NORMAL. GOES DERIVED TPW VERIFIES THE MOISTURE HANGING AROUND THE VEGAS/WESTERN GREAT BASIN AREA AND UPSTREAM OFF THE CALIFORNIA COAST ASSOCIATED WITH THE WESTERN TROF. THETA SURFACES NEAR 315-320K SHOW THE FLOW TURNING SOUTHWESTERLY AND INCREASING LATE TONIGHT INTO TUESDAY AND DRAWING MOISTURE BACK INTO OUR CWA. PIECES OF THE UPPER JET COMBINE WITH INCREASING LARGE SCALE ASCENT BY THE AFTERNOON WHICH SHOULD BRING AN UPTICK TO THE CONVECTION. THE STORMS LOOK TO LINGER THROUGH THE OVERNIGHT HOURS AS THE JET SLOWLY SAGS SOUTHWARD AND ASCENT INCREASES. TEMPERATURES SHOULD BE MAKING A REBOUND TO ABOVE NORMAL BY TOMORROW BEFORE A WEAK FRONT PASSES THROUGH THE MID WEEK. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 356 PM MDT MON SEP 16 2013 A CHANGE IN PATTERN FROM THE STAGNANT MONSOON FLOW TO PROGRESSIVE WESTERLIES OCCURS THIS WEEK...UNOFFICIALLY ENDING THE MONSOON SEASON. WEDNESDAY A PACIFIC TROUGH WORKS THROUGH THE NORTHERN ROCKIES. A WARM SW GRADIENT WIND WILL MIX DOWN IN THE AFTERNOON FOR BREEZY WARM CONDITIONS. RESIDUAL MOISTURE IS SUFFICIENT FOR SCATTERED MAINLY MOUNTAIN SHOWERS AND STORMS. THE ASSOCIATED COOL AND DRY FRONT PUSHES INTO NE UTAH IN THE AFTERNOON PUSHES THROUGH THE NORTHERN AND CENTRAL ZONES BECOMING STRETCHED WEST TO EAST SOMEWHERE NEAR THE HIGHWAY 50 LINE BY THURSDAY MORNING. THIS WILL USHER IN A DRIER AND COOLER AIR MASS FOR THURSDAY. TEMPERATURES ACROSS PORTIONS OF NW COLORADO WILL FLIRT WITH THE FREEZING. TEMPERATURES WILL RECOVER ON FRIDAY INTO SATURDAY TO NEAR NORMAL. THEN NEXT PACIFIC TROUGH IS CURRENTLY TIMED TO PASS LATE SUNDAY... WITH ANOTHER TROUGH LATER NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1010 PM MDT MON SEP 16 2013 VFR IS EXPECTED TO BE THE PREVAILING CONDITION AT THE TAF SITES FOR THE REMAINDER OF TONIGHT THROUGH TUESDAY. AN ISOLATED -SHRA OR -TSRA IS POSSIBLE OVER THE SAN JUAN MTNS THROUGH 18Z TUE. ISOLATED TO SCATTERED -TSRA ARE EXPECTED BETWEEN 18Z TUE AND 03Z WED WITH THE GREATER COVERAGE OVER THE HIGHER TERRAIN. MVFR CIGS AND GUSTY OUTFLOW WINDS NEAR THE -TSRA WITH SOME MOUNTAIN TOP OBSCURATIONS. ALSO...SOUTH TO SOUTHWEST SURFACE GRADIENT WINDS INCREASE TUE AFTERNOON. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...JAD SHORT TERM...15 LONG TERM...JOE AVIATION...JAD
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1002 PM EDT WED SEP 18 2013 .SYNOPSIS... HIGH PRESSURE WILL GRADUALLY SLIDE EAST OF THE REGION THROUGH THE END OF THE WEEK PROVIDING MAINLY DRY WEATHER AND WARMING TEMPERATURES THROUGH SATURDAY. A COLD FRONT WILL ENTER THE REGION SAT NIGHT AND SUNDAY WITH SCATTERED RAIN SHOWERS POSSIBLE. THEN LOTS OF UNCERTAINTY FOR NEXT WEEK AS LOW PRESSURE WITH TROPICAL ORIGINS MAY DEVELOP OVER THE GULF OF MEXICO AND THEN TRACK NORTHEAST INTO THE MID ATLANTIC REGION. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... 10 PM UPDATE... SKC CONDITIONS AND LIGHT TO CALM SW FLOW HAS ALLOWED RADIATIONAL PROCESSES TO BE MORE EFFICIENT THAN GUIDANCE FORECAST. TEMPS ARE ALREADY IN THE LOW 50S AND UPPER 40S IN AREAS WHERE THE GUIDANCE SUGGESTS TEMPS SHOULD BE IN THE UPPER 50S. LATEST MAV AND LAV GUIDANCE BASED ON RUC ARE CLOSEST BUT THESE TOO REQUIRED SOME TWEAKS. OTHER FORECAST PARAMETERS ARE ARE ON TRACK SO NO CHANGES NECESSARY OUTSIDE OF TEMPS/DWPTS. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... HIGH PRESSURE REMAINS IN CONTROL THROUGH THURSDAY NIGHT AS THE HIGH PRESSURE CENTER SLIDES EAST SLOWLY JUST SOUTH OF SOUTHERN NEW ENGLAND. TEMPERATURES CONTINUE TO MODERATE AS THE MID LEVEL RIDGE CRESTS OVER THE AREA DURING THE DAY. TEMPERATURES ARE EXPECTED TO BE IN THE UPPER 70S WITH A FEW LOCATIONS POSSIBLY HITTING 80 IN WESTERLY DOWNSLOPING LIGHT WINDS. OVERNIGHT...LOWS WILL BE STILL A FEW DEGREES WARMER...GENERALLY IN THE 50S. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... HIGHLIGHTS... * DRY AND MILD WEATHER FRI INTO SAT AFTERNOON * COLD FRONT BRINGS A PERIOD OF RAIN SHOWERS SAT NIGHT/SUN * COOLER EARLY NEXT WEEK WITH POSSIBLE RAIN GOOD MODEL AGREEMENT ON RIDGING ACROSS THE NORTHEAST FRI AND SAT PROVIDING DRY AND WARM WEATHER TO SOUTHERN NEW ENGLAND. NORTHERN STREAM TROUGH AND ATTENDING COLD FRONT EXITS THE GREAT LAKES SAT. GOOD MODEL AGREEMENT ON NORTHERN STREAM TROUGH DEAMPLIFYING AS IT TRAVERSE NORTHEAST INTO ONTARIO/QUEBEC. THE QUESTION THEN BECOMES HOW MUCH JET ENERGY IS LEFT BEHIND OVER THE SOUTHERN STATES AS THE NORTHERN STREAM TROUGH SHEARS/PEELS OFF TO THE NORTHEAST. MODELS HANDLING THE SPLITTING OF THIS JET ENERGY VERY DIFFERENTLY...THUS VERY LOW CONFIDENCE FROM SUN INTO EARLY NEXT WEEK. THE 18/12Z GUIDANCE INCLUDING THE GEFS CONTINUES TO SUGGEST A TROPICAL LOW IN THE SOUTHWEST GULF OF MEXICO WILL EJECT NORTHEASTWARD AND INTERACT WITH A DECAYING/FRACTURED FRONTAL BOUNDARY ALONG THE EAST COAST SUN INTO EARLY NEXT WEEK. 12Z GFS SUGGEST A CLOSE CALL WITH CYCLONE EXITING OFF THE MID ATLC COAST. 12Z ECMWF HAS BACKED OFF ITS ROBUST 00Z SOLUTION. THE 12Z ENSEMBLES /BOTH GEFS AND ECENS/ INDICATE LOTS OF SPREAD IN THE H5 FIELD. HENCE LOW CONFIDENCE FORECAST. WILL STICK WITH CHANCE POPS SUN THROUGH WED TO COMMUNICATE THE POTENTIAL FOR SHOWERS AND THE UNCERTAINTY. AS FOR POPS AND TEMPS WERE DERIVED FROM AN EVEN BLEND OF HPC AND GMOS. DETAILS... FRI... NICE WEATHER CONTINUES WITH HIGH PRES NEARBY PROVIDING LIGHT WINDS ALONG WITH WARM TEMPS AND DRY CONDITIONS. SAT... HIGH PRES MOVES FARTHER OFFSHORE WITH INCREASING SSW WINDS YIELDING HIGHER DEW PTS /ALBEIT MODEST WITH VALUES IN THE 60S/ INTO SOUTHERN NEW ENGLAND. NEVERTHELESS NICE SEP WEATHER CONTINUES WITH HIGHS IN THE MU70S. LOW RISK OF A SHOWERS LATE IN THE DAY EXTREME WESTERN NEW ENGLAND. SATURDAY NIGHT THROUGH SUNDAY NIGHT... A COLD FRONT WILL SLOWLY MOVE ACROSS THE REGION YIELDING SCATTERED SHOWERS. NOT EXPECTING A WASHOUT AT THIS POINT. INSTABILITY LOOKS RATHER LIMITED...SO HAVE DECIDED NOT KEEP THUNDER OUT OF THE FORECAST MONDAY THROUGH WEDNESDAY... AS MENTIONED ABOVE LOTS OF UNCERTAINTY REGARDING THIS PORTION OF THE FORECAST. WILL KEEP CHANCE POPS IN THE FORECAST TO ADDRESS THIS UNCERTAINTY. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH THURSDAY NIGHT/...HIGH CONFIDENCE. 7 PM UPDATE... NO CHANGES FROM PREVIOUS FORECAST. VFR THROUGH THE PERIOD EXCEPT FOR A FEW SPOTS OF PATCHY GROUND FOG IN THE TYPICALLY PRONE LOCATIONS LATE TONIGHT AND AGAIN THURSDAY NIGHT. WINDS ARE CURRENTLY STRONG ENOUGH /3-5 KTS/ THAT A SEA BREEZE HAS NOT YET FORMED. HOWEVER...THEY ARE ON THE LIGHT SIDE SO THE WINDS COULD SHIFT TO THE EAST OR SOUTHEAST AT ANY POINT THIS AFTERNOON. KBOS TERMINAL...HIGH CONFIDENCE IN VFR CONDITIONS AND TAF. SOUTHEAST SEA BREEZE LIKELY. KBDL TERMINAL...HIGH CONFIDENCE IN VFR CONDITIONS AND TAF. OUTLOOK...FRIDAY THROUGH MONDAY... FRI AND SAT...HIGH CONFIDENCE FOR VFR/LIGHT WINDS AND DRY WEATHER. SAT NIGHT/SUN/MON...MODERATE CONFIDENCE. A PERIOD OR TWO OF MVFR- IFR CONDITIONS ARE POSSIBLE IN SOME RAIN SHOWERS. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. SHORT TERM /THROUGH THURSDAY NIGHT/...HIGH CONFIDENCE. HIGH PRESSURE BUILDS OVER THE WATERS THROUGH THURSDAY NIGHT. THEREFORE...QUIET BOATING WEATHER IS EXPECTED. OUTLOOK...FRIDAY THROUGH MONDAY... FRI...NICE BOATING WEATHER CONTINUES WITH LIGHT WINDS/GOOD VSBY AS HIGH PRES REMAINS NEARBY. SAT...HIGH MOVES OFFSHORE WITH INCREASING SSW WINDS. POSSIBLE SHOWERS SAT NIGHT FROM WEST TO EAST. SUN/MON...LOTS OF UNCERTAINTY REGARDING LOW PRES EXITING THE GULF OF MEXICO TO THE MID ATLC STATES. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...NONE. && $$ SYNOPSIS...NOCERA/RLG NEAR TERM...DOODY SHORT TERM...RLG LONG TERM...NOCERA AVIATION...NOCERA/RLG MARINE...NOCERA/RLG
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
230 PM EDT TUE SEP 17 2013 .SYNOPSIS... 18Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN UPPER LEVEL PATTERN THAT IS HIGHLY AMPLIFIED TO THE NORTH THROUGH THE MIDDLE SECTION OF THE COUNTRY. THIS LARGE RIDGE SITS BETWEEN TWO SHARP TROUGHS ALONG BOTH THE PACIFIC AND ATLANTIC SEABOARDS. THE FLORIDA PENINSULA RESIDES UNDER A WEAK UPPER LEVEL PATTERN ON THE EASTERN PERIPHERY OF ELONGATED UPPER RIDGING ALONG THE NORTHERN GULF COAST. AT THE SURFACE...FORECAST AREA RESIDES WITHIN A FAIRLY TIGHT PRESSURE GRADIENT ZONE BETWEEN STRONG 1025+MB HIGH PRESSURE RIDGING DOWN THE ATLANTIC SEABOARD...AND A WEAK AREA OF LOW PRESSURE NEAR THE YUCATAN PENINSULA OF MEXICO. THIS GRADIENT IS PROVIDING A DEFINED EASTERLY TO NORTHEASTERLY LOW LEVEL FLOW ACROSS THE PENINSULA. SCT TO NMRS GENERALLY SHALLOW SHOWERS AND A FEW STORMS ARE NOW FORMING INLAND FROM THE FL EAST COAST AND RAPIDLY PROPAGATING WESTWARD WITHIN THIS FLOW. THE GREATEST COVERAGE OF STORMS THROUGH THE REMAINDER OF THE AFTERNOON LOOKS TO BE SOUTH OF THE I-4 CORRIDOR...WITH MORE WIDELY SCT ACTIVITY FURTHER TO THE NORTH ACROSS THE NATURE COAST. THIS SCENARIO IS IN GOOD AGREEMENT WITH THE LATEST HI-RESOLUTION GUIDANCE ENSEMBLE. && .SHORT TERM (TONIGHT THROUGH THURSDAY)... TONIGHT... SHOWERS AND STORMS PUSH OFFSHORE DURING THE EVENING HOURS...AND THE PATTERN SUGGEST WE WILL LIKELY SEE AT LEAST SOME CONVECTIVE COVERAGE OVER THE SOUTHERN COASTAL WATERS WELL INTO THE OVERNIGHT. HIGH PRESSURE BUILDING DOWN THE EASTERN SEABOARD FROM THE MID-ATLANTIC STATES WILL ALSO SET UP A GOOD SYNOPTIC PATTERN TO SUPPORT A NOCTURNAL EASTERLY WIND SURGE OVER THE COASTAL WATERS. THIS SURGE THAT IS FORECAST TO REACH CAUTIONARY LEVELS...SHOULD BEGIN SHORTLY AFTER SUNSET...AND BE MOST NOTABLE THE FURTHER NORTH FROM ENGLEWOOD ONE TRAVELS. WEDNESDAY/WEDNESDAY NIGHT... THE SYNOPTIC SETUP FOR WEDNESDAY APPEARS VERY SIMILAR TO WHAT WE ARE EXPERIENCING TODAY (TUESDAY). UPPER LEVELS SHOW WEAK FLOW ON THE EASTERN SIDE OF A BROAD...BUT NOT STRONG....UPPER RIDGE. AT THE SURFACE...RIDGING CONTINUES TO BUILD DOWN THE EASTERN SEABOARD...AND IF ANYTHING...THE GRADIENT IS TIGHTER AND THE RESULTING LOW LEVEL FLOW A TAD STRONGER. ONCE AGAIN THE COLUMN WILL BE QUITE MOIST...AND THIS COMBINED WITH THE FAVORABLE EASTERLY FLOW SHOULD SUPPORT SCT-NMRS SHOWERS AND STORMS...WITH THE GREATEST COVERAGE ALONG AND SOUTH OF I-4. CURRENT FORECAST RAIN CHANCES SHOW 60-65% ALONG AND SOUTH OF I-4 AND 40-55% FURTHER NORTH. ASIDE FROM THE ACTUAL RAIN CHANCES...THE MID-LEVELS DO NOT LOOK TO SUPPORT MANY STRONGER UPDRAFTS. 500MB TEMPS ARE FAIRLY WARM AT -6C AND THIS SHOULD HELP SUPPRESS MUCH IN THE WAY OF STRONG/SEVERE STORMS...AND EVEN EFFICIENT CHARGE SEPARATION FOR MANY FREQUENT LIGHTNING PRODUCERS. OF COURSE...ALL LIGHTNING IS DANGEROUS...REGARDLESS OF ITS FREQUENCY. THE SPATIAL AND TEMPORAL EVOLUTION OF THE STORMS SHOULD FOLLOW A SIMILAR PATTERN TO TUESDAY AS WELL. DAY WILL START WITH SPEED CONVERGENCE SHOWERS ALONG THE FLORIDA EAST COAST. THESE WILL STRUGGLE TO MOVE INLAND THROUGH LATE MORNING AND THEN CONVECTION WILL BEGIN INLAND ALONG RESIDUAL OUTFLOW BOUNDARIES AND PROPAGATE RAPIDLY WESTWARD ACROSS OUR ZONES. TEMPERATURES APPEAR SEASONABLE BY MID-AFTERNOON REACHING THE LOW 90S FOR MOST SPOTS THAT DO NOT SEE AN EARLY SHOWER. ANY LEFTOVER EVENING STORMS PUSH OFFSHORE BY 02-03Z LEAVING A GENERALLY DRY OVERNIGHT INTO EARLY THURSDAY MORNING. THE RIDGE POSITION TO OUR NORTH WILL SUPPORT ANOTHER CAUTIONARY EASTERLY WIND SURGE FOR THE COASTAL WATERS...ESPECIALLY FROM OFFSHORE OF TAMPA BAY NORTHWARD ALONG THE NATURE COAST. THURSDAY... PATTERN STILL DOES NOT CHANGE A WHOLE LOT INTO THURSDAY. A SLIGHTLY MORE AMPLIFIED MID/UPPER LEVEL RIDGE TO OUR WEST IS SHOWN BY THE GFS TO BEGIN DELIVERING SOME DRIER MID-LEVEL AIR TO THE NATURE COAST ZONES BEFORE THE DAY IS THROUGH. DEPENDING ON THE EXACT TIMING OF THIS DRIER AIR...RAIN CHANCES FOR THE NATURE COAST MAY NEED TO BE ADJUSTED DOWNWARD SLIGHTLY. EITHER WAY...BEST RAIN CHANCES THURSDAY AFTERNOON/EARLY EVENING WILL ONCE AGAIN BE ALONG AND SOUTH OF I-4. CURRENTLY FORECASTING 55-65% SOUTH OF I-4 AND 30-45% FURTHER NORTH. && .LONG TERM (FRIDAY THROUGH NEXT MONDAY)... MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT THROUGH THE REMAINDER OF THE WORK WEEK...WITH SOLUTIONS THEN DIVERGING OVER THE UPCOMING WEEKEND AND INTO EARLY NEXT WEEK. THE 00Z CANADIAN MODEL COMPARED WITH THE GFS/ECMWF IS DEVELOPING A TROPICAL CYCLONE IN THE GULF OF MEXICO BY SATURDAY EVENING. ALTHOUGH NOT IMPOSSIBLE GIVEN THE GENERALLY FAVORABLE CONDITIONS OVER THE GULF...ONE OF THE BIASES OF THE CANADIAN MODEL IS TO OVERDEVELOP TROPICAL CYCLONES DUE TO INTERACTION WITH LARGE SCALE SYNOPTIC FEATURES. AS A RESULT...WILL FOLLOW A BLEND OF THE 00Z GFS AND 00Z ECMWF FOR FORECAST DETAILS THROUGH THE LONG TERM PERIODS. HIGH PRESSURE WILL REMAIN NORTH OF THE FORECAST AREA FOR THE TAIL END OF THE WORK WEEK AND INTO THE UPCOMING WEEKEND...RESULTING IN PREVAILING EASTERLY FLOW WITH ISOLATED TO WIDELY SCATTERED SEA BREEZE DRIVEN CONVECTION EACH AFTERNOON/EVENING THROUGH SATURDAY. HIGH PRESSURE NORTH OF THE STATE WILL WEAKEN AS A FRONTAL BOUNDARY PUSHES SOUTHWARD TOWARD THE NORTHERN GULF COAST AND STALLS OUT BY SUNDAY. THIS WILL RESULT IN AN INCREASE IN DEEP LAYER MOISTURE ACROSS THE ENTIRE FORECAST AREA...SUNDAY THROUGH NEXT TUESDAY. THE GFS AND ECMWF MODELS TO DIFFERING DEGREES CONTINUE TO SHOW A BROAD AREA OF LOW PRESSURE WITH PLENTY OF DEEP LAYER MOISTURE IN PLACE OVER THE GULF OF MEXICO. THE CANADIAN ON THE OTHER HAND AS MENTIONED ABOVE...HAS A FAIRLY IMPRESSIVE TROPICAL CYCLONE MAKING LANDFALL ALONG THE NORTHERN GULF COAST ON SUNDAY. GIVEN THE TIME OF YEAR AND SOME INDICATIONS OF POTENTIAL DEVELOPMENT IN THE NUMERICAL MODEL GUIDANCE...WILL NEED TO CLOSELY MONITOR TRENDS AS THE WEEK PROGRESSES FOR THE POTENTIAL FOR TROPICAL CYCLONE DEVELOPMENT. TEMPERATURES ARE EXPECTED TO RUN CLOSE TO CLIMO THROUGH THE LONG TERM PERIODS. && .AVIATION... VFR CONDITIONS ARE GIVING WAY TO SOME TEMPO MVFR/LCL IFR... ESPECIALLY AT PGD/FMY/RSW. ALL TERMINALS ARE EXPECTED TO SEE VCNTY TSRA THROUGH 00/01Z...THEN VFR RETURNS. EASTERLY FLOW PREVAILS ALTHOUGH WINDS OVERNIGHT WILL BACK AND SLACKEN SOME. && .MARINE... EASTERLY WINDS WILL CONTINUE FOR THE NEXT SEVERAL DAYS. HIGH PRESSURE BUILDING DOWN THE EASTERN SEABOARD FROM THE MID-ATLANTIC STATES WILL ALSO SET UP A GOOD SYNOPTIC PATTERN TO SUPPORT A NOCTURNAL EASTERLY WIND SURGE OVER THE COASTAL WATERS. THIS SURGE IS FORECAST TO REACH CAUTIONARY LEVELS...SHOULD BEGIN SHORTLY AFTER SUNSET...AND BE MOST NOTABLE THE FURTHER NORTH FROM ENGLEWOOD ONE TRAVELS. ANOTHER EASTERLY SURGE TO CAUTIONARY LEVELS CAN BE EXPECTED WEDNESDAY NIGHT. && .FIRE WEATHER... HIGH PRESSURE TO OUR NORTH THE NEXT SEVERAL DAYS WILL KEEP A MOIST EASTERLY FLOW OFF THE ATLANTIC A FEATURE OF THE FORECAST. RELATIVE HUMIDITY IS EXPECTED TO REMAIN WELL ABOVE CRITICAL LEVELS THROUGH THE NEXT SEVERAL DAYS. ONLY FIRE WEATHER CONCERN BESIDES THE CONTINUED THREAT FOR SCATTERED AFTERNOON STORMS WILL BE HIGH DISPERSION INDICES THAT WILL APPROACH FOR SURPASS 75 TO THE NORTH OF I-4 THE BOTH WEDNESDAY AND THURSDAY AFTERNOONS. SOME PATCHY GROUND FOR IS POSSIBLE LATE THE NEXT FEW NIGHTS FOR LOCATIONS THAT RECEIVE LATE DAY RAINS...BUT NO SIGNIFICANT FOG DEVELOPMENT IS ANTICIPATED. && .HYDROLOGY... RECENT RAINFALL HAS CAUSED ELEVATED WATER LEVELS ON MANY RIVERS AND ACROSS THE AREA. CURRENTLY...THE LITTLE MANATEE RIVER NEAR WIMAUMA AND THE MANATEE RIVER AT MYAKKA HEAD ARE IN ACTION STAGE...AND ALTHOUGH WATER LEVELS ON THESE RIVERS ARE EXPECTED TO DECREASE TODAY...ADDITIONAL RAINFALL LATER THIS WEEK MAY BRING THESE RIVERS BACK ABOVE FLOOD STAGE. && .PRELIMINARY POINT TEMPS/POPS... TPA 75 90 75 90 / 20 60 20 50 FMY 73 91 74 91 / 20 60 20 60 GIF 72 91 72 91 / 10 60 20 50 SRQ 74 90 74 92 / 20 60 20 50 BKV 71 91 71 91 / 20 50 20 40 SPG 77 90 77 90 / 20 60 20 50 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA AVIATION...RUDE LONG TERM...JELSEMA HYDROLOGY...LEWIS
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
1020 AM EDT TUE SEP 17 2013 .SHORT TERM (TODAY-THURSDAY)... 14Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN UPPER LEVEL PATTERN THAT IS HIGHLY AMPLIFIED TO THE NORTH THROUGH THE MIDDLE SECTION OF THE COUNTRY FOR THE MIDDLE OF SEPTEMBER. THIS LARGE RIDGE SITS BETWEEN TWO SHARP TROUGHS ALONG BOTH THE PACIFIC AND ATLANTIC SEABOARDS. THE FLORIDA PENINSULA RESIDES UNDER A WEAK UPPER LEVEL PATTERN ON THE EASTERN PERIPHERY OF ELONGATED UPPER RIDGING ALONG THE NORTHERN GULF COAST. 12Z KTBW SOUNDING PROFILE IS RATHER MOIST WITH A PW VALUE APPROACHING 2". HOWEVER...LAPSE RATE...ESPECIALLY IN THE MID-LEVELS / HAIL GROWTH ZONE ARE NOT IMPRESSIVE. THE MOIST ATMOSPHERE AND EASTERLY LOW LEVEL FLOW REGIME SUGGEST WE WILL STILL HAVE AN ACTIVE CONVECTIVE AFTERNOON/EARLY EVENING...ESPECIALLY FROM I-4 SOUTHWARD...BUT MUCH ROBUST CONVECTION WITH SEVERE SUPPORTIVE UPDRAFTS APPEARS UNLIKELY. ISOLATED CONVECTIVE CELL CAN ALWAYS SURPRISE YOU IF IT FINDS A LOCAL REGION OF GOOD LOW LEVEL FOCUS...BUT OVERALL A MORE MODERATED DAY OF CONVECTIVE STRENGTH SEEMS LIKELY. HAVE SEEN SOME SHOWERS/STORMS ALONG THE FLORIDA EAST COAST WITHIN THE ZONE OF EASTERLY SPEED CONVERGENCE. AS WOULD BE EXPECTED...THIS ACTIVITY DISSIPATES QUICKLY AS IT TRIES TO MOVE INLAND AND AWAY FROM THIS NARROW FOCUS ZONE. WITH THIS IN MIND...SHOULD HAVE A FEW MORE HOURS OF GENERALLY DRY CONDITIONS ACROSS OUR FORECAST AREA BEFORE DIURNAL HEATING AND RESIDUAL OUTFLOW BOUNDARIES START THE EARLY AFTERNOON CONVECTIVE PROCESS. BASED ON LATEST HI-RES CONVECTIVE ALLOWING GUIDANCE SUITE...CURRENT LATE DAY RAIN CHANCES OF 25-40% NORTH OF I-4 AND 50-60% FURTHER SOUTH STILL APPEAR ON TRACK. THE DEEPEST MOISTURE IS CERTAINLY OVER THE SOUTHERN 2/3RDS OF THE FORECAST AREA THIS AFTERNOON AND IS LIKELY WHAT THE GUIDANCE IS PICKING UP ON TO SUPPORT THE GREATER CONVECTIVE COVERAGE FROM TAMPA BAY SOUTHWARD. TONIGHT... SHOWERS AND STORMS PUSH OFFSHORE DURING THE EVENING HOURS...AND THE PATTERN SUGGEST WE WILL LIKELY SEE AT LEAST SOME CONVECTIVE COVERAGE OVER THE SOUTHERN COASTAL WATERS WELL INTO THE OVERNIGHT. HIGH PRESSURE BUILDING DOWN THE EASTERN SEABOARD FROM THE MID-ATLANTIC STATES WILL ALSO SET UP A GOOD SYNOPTIC PATTERN TO SUPPORT A NOCTURNAL EASTERLY WIND SURGE OVER THE COASTAL WATERS. THIS SURGE IS FORECAST TO REACH CAUTIONARY LEVELS...SHOULD BEGIN SHORTLY AFTER SUNSET...AND BE MOST NOTABLE THE FURTHER NORTH FROM ENGLEWOOD ONE TRAVELS. && .AVIATION... VFR CONDITIONS ARE EXPECTED TO PREVAIL AT ALL TERMINALS THIS MORNING INTO THE EARLY AFTERNOON HOURS. SCATTERED SHRA/TSRA SHOULD DEVELOP EARLY AFTERNOON...SO WILL CURRENTLY KEEP VCTS AT 18Z FOR SOUTHERN AIRPORTS AND 19Z FROM SRQ NORTHWARD. WILL HAVE TO MONITOR THIS AND ADJUST WITH TEMPO GROUPS FOR POSSIBLE CIG/VIS CONDITIONS IN TSRA AS SHOWERS/STORMS MOVE WESTWARD. VFR CONDITIONS ARE EXPECTED OVERNIGHT. && .MARINE... EASTERLY WINDS WILL CONTINUE FOR THE NEXT SEVERAL DAYS. HIGH PRESSURE BUILDING DOWN THE EASTERN SEABOARD FROM THE MID-ATLANTIC STATES WILL ALSO SET UP A GOOD SYNOPTIC PATTERN TO SUPPORT A NOCTURNAL EASTERLY WIND SURGE OVER THE COASTAL WATERS. THIS SURGE IS FORECAST TO REACH CAUTIONARY LEVELS...SHOULD BEGIN SHORTLY AFTER SUNSET...AND BE MOST NOTABLE THE FURTHER NORTH FROM ENGLEWOOD ONE TRAVELS. ANOTHER EASTERLY SURGE TO CAUTIONARY LEVELS CAN BE EXPECTED WEDNESDAY NIGHT. && .PRELIMINARY POINT TEMPS/POPS... TPA 90 75 90 75 / 50 20 50 20 FMY 89 73 90 74 / 60 20 60 20 GIF 91 72 91 72 / 50 20 50 20 SRQ 91 74 90 74 / 50 20 60 20 BKV 91 70 91 70 / 40 20 50 20 SPG 90 77 89 77 / 50 20 60 20 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ UPDATE/MARINE...MROCZKA AVIATION...RUDE/WYNN
AREA FORECAST DISCUSSION
NWS POCATELLO ID
750 AM MDT TUE SEP 17 2013 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT. A QUICK UPDATE THIS MORNING TO ADD SEVERE WORDING TO GOING FORECAST THIS AFTERNOON AS INCOMING FRONT AND UPPER DYNAMICS COMBINE TO PRODUCE VERY STRONG THUNDERSTORMS. SEE PREVIOUS DISCUSSION BELOW. HUSTON A VERY ACTIVE 48 HOUR PERIOD IS AHEAD FOR EASTERN IDAHO. WE ALREADY HAD A ROUND OF STRONG/SEVERE STORMS THIS MORNING AND ANOTHER ROUND IS ON TAP FOR LATER TODAY. THE MAIN FEATURE WITH STORM OFFSHORE WILL SWING INTO WASHINGTON AND OREGON. THIS...ALONG WITH A COLD FRONT ENTERING INTO WESTERN PORTIONS OF THE FORECAST AREA WILL KEEP SHOWERS AND THUNDERSTORMS AROUND WITH COVERAGE RAMPING UP THIS AFTERNOON. MOST AREAS WILL SEE SCATTERED TO NUMEROUS SHOWERS AND STORMS...WITH EXCEPTION FOR THE MAGIC VALLEY AND WEST OF OAKLEY WHERE ISOLATED ACTIVITY IS FORECAST. THE FRONT SHOULD BE THROUGH THEM BEFORE THINGS GET GOING. THE THREAT OF STRONG/SEVERE STORMS WITH HAIL AND STRONG WINDS EXISTS TODAY ESPECIALLY ACROSS THE MOUNTAINS AND ALONG/AHEAD OF THE COLD FRONT ACROSS THE SNAKE PLAIN. BY TONIGHT AND WEDNESDAY...THE FOCUS FOR SHOWERS WILL SHIFT TO THE CENTRAL MOUNTAINS AND UPPER SNAKE HIGHLANDS. I KNOW SOME AREN`T GOING TO BE READY OR LIKE THIS..BUT LIGHT SNOW IS FORECAST ABOVE 7500FT TONIGHT/EARLY WEDNESDAY ACROSS THE CENTRAL MOUNTAINS. YOU CAN EXPECT BREEZY/WINDY CONDITIONS ACROSS THE AREA...WITH SOUTHERLY WINDS AHEAD OF THE FRONT AND MORE WESTERLY IN ITS WAKE. SUSTAINED WINDS OF 15-30MPH WITH HIGHER GUSTS ARE LIKELY...OUTSIDE OF THUNDERSTORMS...THROUGH THIS EVENING. THE RIDGETOPS MAY SEE SUSTAINED WINDS CLOSER TO 30-35MPH AT THEIR PEAK. WIND SPEEDS COME DOWN SOME ESPECIALLY ACROSS THE CENTRAL MOUNTAINS AND UPPER SNAKE HIGHLANDS TONIGHT AND TOMORROW. THEY`LL STILL BE BREEZY ACROSS MOST OF THE SNAKE PLAIN AND SOUTHERN MOUNTAINS HOWEVER. WE HAVE A LAKE WIND ADVISORY OUT FOR THIS AFTERNOON UNTIL JUST BEFORE SUNSET. ANOTHER ONE IS LIKELY FOR TOMORROW AS WELL. CONDITIONS ARE JUST NOT QUITE THERE FOR A WIND ADVISORY AT LOWER ELEVATIONS BUT WE WILL BE MONITORING THIS AS WINDS WILL BE FLIRTING WITH THE LOWER THRESHOLD OF 30MPH SUSTAINED TOMORROW. IT WILL CERTAINLY FEEL LIKE FALL WITH COLDER TEMPERATURES ARRIVING BEHIND THE FRONT. WE ARE LOOKING AT A 10-15 DEGREE DIFFERENCE BETWEEN TODAY AND TOMORROW...WITH THE VALLEYS STRUGGLING TO GET ABOVE 65. WEDNESDAY NIGHT WILL BE DOWNRIGHT COLD IN SOME AREAS. IT LOOKS LIKE MANY AREAS WILL SEE 20S AND 30S FOR LOWS. THE EXCEPTIONS WILL BE ACROSS THE SOUTHERN HIGHLANDS WHERE VALLEY TEMPERATURES WILL BOTTOM OUT IN THE LOW 40S..AND PLACES LIKE STANLEY AND COPPER BASIN WHERE IT WILL DROP INTO THE TEENS. KEYES .LONG TERM...THURSDAY THROUGH NEXT TUESDAY. THE END OF THE WEEK WILL SEE HIGH PRESSURE BUILDING AND SHIFTING EASTWARD OVER IDAHO. THIS WILL ALLOW FOR A QUICK WARMUP WITH DRY CONDITIONS THROUGH SATURDAY MORNING. FOR THE TRUE ARRIVAL OF FALL EARLY NEXT WEEK...THE OVERALL PATTERN SETTLES BACK INTO GENERAL LOW PRESSURE OVER THE WEST. THERE WILL BE MULTIPLE SYSTEMS IN THE PATTERN THAT WILL KEEP THE CHANCE OF SHOWERS AROUND WITH A FEW THUNDERSTORMS. KEYES && .AVIATION...TRONG SHOWERS AND THUNDERSTORMS HAVE PASSED TO THE DOWNWIND SIDE OF ALL AIRDROMES EXCEPT KIDA. -TSRA WILL CONTINUE AND INCREASE IN COVERAGE AS INSTABILITY DEVELOPS AHEAD OF A COLD FRONT EXPECTED LATE THIS AFTERNOON/EARLY THIS COMING EVENING...PASSING THROUGH ALL AIRDROMES BY 18/03Z. -TSRA PROBABILITY BORDERS ON 50 PERCENT FOR KIDA AND KPIH...BUT TEMPO GROUPS NOT ALLOWED BEYOND 6 HOUR POINT. WILL TRY TO USE LATEST HRRR GUIDANCE TO FORECAST A THUNDERSTORM TIME. FRONTAL PASSAGE IS FROM WEST TO EAST...WITH KIDA BEING THE LAST. STRONG GRADIENT BEHIND THE FRONT MEANS AN UNUSUALLY WINDY OVERNIGHT PERIOD TONIGHT. STRONG WIND CONTINUES WED AFTERNOON. MESSICK && .FIRE WEATHER...ERY UNSTABLE CONDITIONS TODAY WITH A FRONT ARRIVING IN THE LATE AFTERNOON OVER EASTERN IDAHO. EXPECT A STORMY AND WINDY DAY...CONTINUING INTO A STORMY AND WINDY NIGHT. FRONT WILL PASS OUT OF EASTERN IDAHO BY MIDNIGHT TONIGHT...BUT STRONG WINDS WILL CONTINUE OVERNIGHT AND INCREASE AGAIN TOMORROW AFTERNOON. THUNDERSTORM ACTIVITY WILL BE LIMITED ON WED TO MAINLY THE TARGHEE PORTION OF THE CARIBOU-TARGHEE NF. HIGH PRESSURE WILL MOVE IN FOR THE LAST HALF OF THE WORK WEEK AND FOR AT LEAST A PORTION OF THE WEEKEND. A STRONG LOW AND COLD FRONT ARE EXPECTED TO REACH IDAHO SAT NIGHT OR SUN MORNING. NEITHER THE FRONT TODAY NOR THE WEEKEND FRONT SHOULD BRING MUCH RAINFALL. MAIN ISSUE WILL BE STRONG WIND WITH A 90 KNOT UPPER LEVEL JET OVERHEAD TODAY MIXING DOWNWARD IN THE UNSTABLE AIR. MESSICK && .PIH WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 7 PM MDT THIS EVENING IDZ021. && $$
AREA FORECAST DISCUSSION
NWS POCATELLO ID
337 AM MDT TUE SEP 17 2013 .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT. A VERY ACTIVE 48 HOUR PERIOD IS AHEAD FOR EASTERN IDAHO. WE ALREADY HAD A ROUND OF STRONG/SEVERE STORMS THIS MORNING AND ANOTHER ROUND IS ON TAP FOR LATER TODAY. THE MAIN FEATURE WITH STORM OFFSHORE WILL SWING INTO WASHINGTON AND OREGON. THIS...ALONG WITH A COLD FRONT ENTERING INTO WESTERN PORTIONS OF THE FORECAST AREA WILL KEEP SHOWERS AND THUNDERSTORMS AROUND WITH COVERAGE RAMPING UP THIS AFTERNOON. MOST AREAS WILL SEE SCATTERED TO NUMEROUS SHOWERS AND STORMS...WITH EXCEPTION FOR THE MAGIC VALLEY AND WEST OF OAKLEY WHERE ISOLATED ACTIVITY IS FORECAST. THE FRONT SHOULD BE THROUGH THEM BEFORE THINGS GET GOING. THE THREAT OF STRONG/SEVERE STORMS WITH HAIL AND STRONG WINDS EXISTS TODAY ESPECIALLY ACROSS THE MOUNTAINS AND ALONG/AHEAD OF THE COLD FRONT ACROSS THE SNAKE PLAIN. BY TONIGHT AND WEDNESDAY...THE FOCUS FOR SHOWERS WILL SHIFT TO THE CENTRAL MOUNTAINS AND UPPER SNAKE HIGHLANDS. I KNOW SOME AREN`T GOING TO BE READY OR LIKE THIS..BUT LIGHT SNOW IS FORECAST ABOVE 7500FT TONIGHT/EARLY WEDNESDAY ACROSS THE CENTRAL MOUNTAINS. YOU CAN EXPECT BREEZY/WINDY CONDITIONS ACROSS THE AREA...WITH SOUTHERLY WINDS AHEAD OF THE FRONT AND MORE WESTERLY IN ITS WAKE. SUSTAINED WINDS OF 15-30MPH WITH HIGHER GUSTS ARE LIKELY...OUTSIDE OF THUNDERSTORMS...THROUGH THIS EVENING. THE RIDGETOPS MAY SEE SUSTAINED WINDS CLOSER TO 30-35MPH AT THEIR PEAK. WIND SPEEDS COME DOWN SOME ESPECIALLY ACROSS THE CENTRAL MOUNTAINS AND UPPER SNAKE HIGHLANDS TONIGHT AND TOMORROW. THEY`LL STILL BE BREEZY ACROSS MOST OF THE SNAKE PLAIN AND SOUTHERN MOUNTAINS HOWEVER. WE HAVE A LAKE WIND ADVISORY OUT FOR THIS AFTERNOON UNTIL JUST BEFORE SUNSET. ANOTHER ONE IS LIKELY FOR TOMORROW AS WELL. CONDITIONS ARE JUST NOT QUITE THERE FOR A WIND ADVISORY AT LOWER ELEVATIONS BUT WE WILL BE MONITORING THIS AS WINDS WILL BE FLIRTING WITH THE LOWER THRESHOLD OF 30MPH SUSTAINED TOMORROW. IT WILL CERTAINLY FEEL LIKE FALL WITH COLDER TEMPERATURES ARRIVING BEHIND THE FRONT. WE ARE LOOKING AT A 10-15 DEGREE DIFFERENCE BETWEEN TODAY AND TOMORROW...WITH THE VALLEYS STRUGGLING TO GET ABOVE 65. WEDNESDAY NIGHT WILL BE DOWNRIGHT COLD IN SOME AREAS. IT LOOKS LIKE MANY AREAS WILL SEE 20S AND 30S FOR LOWS. THE EXCEPTIONS WILL BE ACROSS THE SOUTHERN HIGHLANDS WHERE VALLEY TEMPERATURES WILL BOTTOM OUT IN THE LOW 40S..AND PLACES LIKE STANLEY AND COPPER BASIN WHERE IT WILL DROP INTO THE TEENS. KEYES .LONG TERM...THURSDAY THROUGH NEXT TUESDAY. THE END OF THE WEEK WILL SEE HIGH PRESSURE BUILDING AND SHIFTING EASTWARD OVER IDAHO. THIS WILL ALLOW FOR A QUICK WARMUP WITH DRY CONDITIONS THROUGH SATURDAY MORNING. FOR THE TRUE ARRIVAL OF FALL EARLY NEXT WEEK...THE OVERALL PATTERN SETTLES BACK INTO GENERAL LOW PRESSURE OVER THE WEST. THERE WILL BE MULTIPLE SYSTEMS IN THE PATTERN THAT WILL KEEP THE CHANCE OF SHOWERS AROUND WITH A FEW THUNDERSTORMS. KEYES && .AVIATION...TRONG SHOWERS AND THUNDERSTORMS HAVE PASSED TO THE DOWNWIND SIDE OF ALL AIRDROMES EXCEPT KIDA. -TSRA WILL CONTINUE AND INCREASE IN COVERAGE AS INSTABILITY DEVELOPS AHEAD OF A COLD FRONT EXPECTED LATE THIS AFTERNOON/EARLY THIS COMING EVENING...PASSING THROUGH ALL AIRDROMES BY 18/03Z. -TSRA PROBABILITY BORDERS ON 50 PERCENT FOR KIDA AND KPIH...BUT TEMPO GROUPS NOT ALLOWED BEYOND 6 HOUR POINT. WILL TRY TO USE LATEST HRRR GUIDANCE TO FORECAST A THUNDERSTORM TIME. FRONTAL PASSAGE IS FROM WEST TO EAST...WITH KIDA BEING THE LAST. STRONG GRADIENT BEHIND THE FRONT MEANS AN UNUSUALLY WINDY OVERNIGHT PERIOD TONIGHT. STRONG WIND CONTINUES WED AFTERNOON. MESSICK && .FIRE WEATHER...ERY UNSTABLE CONDITIONS TODAY WITH A FRONT ARRIVING IN THE LATE AFTERNOON OVER EASTERN IDAHO. EXPECT A STORMY AND WINDY DAY...CONTINUING INTO A STORMY AND WINDY NIGHT. FRONT WILL PASS OUT OF EASTERN IDAHO BY MIDNIGHT TONIGHT...BUT STRONG WINDS WILL CONTINUE OVERNIGHT AND INCREASE AGAIN TOMORROW AFTERNOON. THUNDERSTORM ACTIVITY WILL BE LIMITED ON WED TO MAINLY THE TARGHEE PORTION OF THE CARIBOU-TARGHEE NF. HIGH PRESSURE WILL MOVE IN FOR THE LAST HALF OF THE WORK WEEK AND FOR AT LEAST A PORTION OF THE WEEKEND. A STRONG LOW AND COLD FRONT ARE EXPECTED TO REACH IDAHO SAT NIGHT OR SUN MORNING. NEITHER THE FRONT TODAY NOR THE WEEKEND FRONT SHOULD BRING MUCH RAINFALL. MAIN ISSUE WILL BE STRONG WIND WITH A 90 KNOT UPPER LEVEL JET OVERHEAD TODAY MIXING DOWNWARD IN THE UNSTABLE AIR. MESSICK && .PIH WATCHES/WARNINGS/ADVISORIES... LAKE WIND ADVISORY FROM 1 PM THIS AFTERNOON TO 7 PM MDT THIS EVENING IDZ021. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1012 PM CDT WED SEP 18 2013 .DISCUSSION... 336 PM CDT MAIN CHALLENGES/CONCERNS THIS FORECAST PERIOD ARE WITH SHOWERS AND THUNDERSTORMS IN THE NEAR TERM...POSSIBLE PERSISTENT SHOWERS/THUNDERSTORMS OVERNIGHT...AS WELL AS BETTER CHANCES FOR SHOWERS/THUNDERSTORMS THURSDAY NIGHT INTO FRIDAY MORNING. CONTINUE TO MONITOR AREA OF SHOWERS AND THUNDERSTORMS ACROSS NORTH CENTRAL ILLINOIS THAT HAVE CONTINUED TO SLOWLY MOVE EAST TODAY. LATEST RADAR IMAGERY DEPICTING A CONTINUED DEVELOPING TREND IN BOTH COVERAGE AND INTENSITY WITH THIS AREA OF PRECIPITATION...AND EXPECT THIS TO CONTINUE THROUGH THE AFTERNOON AND EARLY EVENING. MCV IS THE MAIN DRIVING FORCE FOR THESE SHOWERS/THUNDERSTORMS...WITH LATEST RAP ANALYSIS SHOWING LOWERING CIN AND AN AXIS OF 1000 J/KG OF SB CAPE EXTENDING INTO NORTHEAST ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH NOT THE GREATEST...THESE CONDITIONS WILL BE ENOUGH TO HELP THIS PRECIP TO HOLD TOGETHER WHILE IT SLOWLY MOVES THROUGH NORTHEAST ILLINOIS THIS AFTERNOON AND THEN NORTHWEST INDIANA THROUGH EARLY EVENING. ALTHOUGH WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED...A PORTION OF THESE STORMS ALONG THE I-80 CORRIDOR HAVE EXHIBITED SOME STRENGTHENING TRENDS WITH BRIEF HIGHER WIND SIGNATURES. SO FOR THIS AFTERNOON/EARLY EVENING...EXPECT ANY OF THE STRONGER STORMS IN THIS GENERAL AREA TO BE CAPABLE OF PRODUCING SPORADIC WIND GUSTS TO 50 MPH...CONTINUOUS LIGHTNING...AND BRIEF HEAVY RAINFALL WITH AN OUTSIDE POSSIBILITY OF AN ISOLATED SEVERE WIND THREAT. WITH THE DEPARTURE OF THESE THUNDERSTORMS...MOST OF THE CWA SHOULD OBSERVE A LULL IN PRECIP BEFORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ONCE AGAIN OVER NIGHT. SEVERAL WEAK MID LEVEL FEATURES WILL CONTINUE TO TRAVERSE CURRENT ZONAL FLOW OVERHEAD...WITH LOW/MID LEVEL FLOW VEERING OVERNIGHT. AS THIS OCCURS...IT APPEARS AS BETTER WAA WILL ORIENT ITSELF MORE TOWARDS NORTHERN ILLINOIS. ALTHOUGH CONFIDENCE IS NOT THE GREATEST FOR COVERAGE TONIGHT...DID MAINTAIN LOW CHANCE POPS FOR MOST AREAS MAINLY AFTER MIDNIGHT OWING TO THIS POTENTIAL. WHATEVER DOES DEVELOP SHOULD BE MORE SCATTERED IN NATURE...AND THEN BEGIN SHIFTING EAST OUT OF THE CWA WHILE DIMINISHING EARLY THURSDAY MORNING. WITH BROAD SOUTHWESTERLY FLOW PERSISTING ON THURSDAY AND A FAIRLY MOIST ENVIRONMENT OVERHEAD...SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE. ALTHOUGH...CHANCES FOR PRECIPITATION SHOULD REMAIN LOW WITH ONCE AGAIN ANYTHING THAT DOES DEVELOP REMAINING SCATTERED. WITH THIS PERSISTENT WAA...CONTINUED WARMUP WILL CONTINUE ON THURSDAY. MADE LITTLE ADJUSTMENTS TO MAX TEMPS FOR THURSDAY KEEPING UPPER 80S FOR MOST LOCATIONS...WITH SOME UNCERTAINTIES TO PRECIP AND EVEN CLOUD COVER REMAINING. IF ENOUGH CLEARING OCCURS...THERMO PROFILES WILL BE SUPPORTIVE OF SOME LOCATIONS REACHING OR SLIGHTLY EXCEEDING 90 DEGREES. MAIN FOCUS FOR THUNDERSTORM DEVELOPMENT SHIFTS TOWARDS THE LATE AFTERNOON AND EARLY EVENING WITH AN APPROACHING TROUGH OF LOW PRESSURE AND COLD FRONT. AS LARGE VORT MAX DROPS SOUTHEAST ACROSS THE NORTHERN PLAINS...SEVERAL WAVES OF ENERGY WILL LIFT NORTHEAST ACROSS THE REGION. THIS WILL HELP TO SHIFT THIS TROUGH/FRONT AS WELL AS INDUCING SOME FURTHER PRESSURE FALLS OUT AHEAD OF IT. WITH POTENTIAL FOR PRE FRONTAL TROUGHINESS TO OCCUR TOMORROW AFTERNOON...SOME GUIDANCE CONTINUES TO DEVELOP PRECIP OUT AHEAD OF THIS FRONT. ALTHOUGH I FEEL THIS IS A BIT OVERDONE...AND HAVE HELD BACK ON POPS FOR THURSDAY DURING THE DAY. HAVE EVEN TRENDED TOWARDS A SLOWER SOLUTION/TREND WITH THIS FRONT/TROUGH WITH BEST CHANCES FOR SHOWERS/THUNDERSTORMS REMAINING OVER WEST/NORTHWEST ILLINOIS FOR MOST OF THURSDAY NIGHT. ITS NOT UNTIL EARLY FRIDAY MORNING THAT THIS FRONT GETS A GOOD SOUTHEAST PUSH WITH BEST FORCING MOVING OVERHEAD. GOOD SWATH OF PRECIP SHOULD SHIFT SOUTHEAST ACROSS THE ENTIRE CWA THROUGH MID DAY FRIDAY...WITH THIS PRECIP THEN EXPECTED TO SHIFT OUT OF THE AREA THROUGH THE AFTERNOON. IT DOES APPEAR AS IF THE STRONGER STORMS SHOULD REMAIN JUST WEST OF THE CWA...BUT WITH SOME POTENTIAL FOR THEM TO REACH THE FAR WESTERN CWA THURSDAY EVENING/NIGHT. IF INSTABILITY CAN INCREASE ON FRIDAY...THERE IS THE POTENTIAL FOR A LINGERING STRONG TO SEVERE THREAT ACROSS THE CWA BEFORE THE STORMS SHIFT OUT OF THE CWA. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 03Z... * LOW CHANCE FOR ADDITIONAL SHRA/TSRA LATE TONIGHT/THURSDAY MORNING. * GUSTY SOUTH-SOUTHWEST WINDS THURSDAY. KJB //DISCUSSION...UPDATED 03Z... THERE CONTINUES TO BE A LOW THREAT FOR ADDITIONAL SCATTERED THUNDERSTORM DEVELOPMENT ACROSS THE AREA OVERNIGHT. A WARM FRONT IS CURRENTLY APPROACHING THE AREA AND WARM MOIST AIR CONTINUES TO LIFT OVER THIS FRONT VIA A LOW LEVEL JET...AND THIS COULD LEAD TO ADDITIONAL STORMS OVERNIGHT. HOWEVER...CONFIDENCE REMAINS LOW REGARDING THE EXTENT OF ACTIVITY...BUT RATHER THAN GETTING RID OF THE PROB 30 GROUP FOR THE UPDATE...I CHOOSE TO ADD IT AS A TEMPO GROUP. //DISCUSSION...UPDATED 00Z... THINGS SHOULD BEGIN QUIETING DOWN NOW FOR MUCH OF THE EVENING. THE LAST BATCH OF THUNDERSTORMS...CURRENTLY ASSOCIATED WITH THE ENHANCED FORCING FOR ASCENT WITH THE MID LEVEL VORT/MCV...IS MOVING ACROSS NORTHEASTERN ILLINOIS. ONCE THIS ACTIVITY MOVES EAST EARLY THIS EVENING...SEVERAL HOURS OF QUITE WEATHER LOOKS TO BE ON TAP FOR THE AREA. THE WINDS ARE BIT DISTURBED FROM THE CURRENT CONVECTIVE ACTIVITY...BUT EXPECT WINDS TO QUICKLY COME BACK OUT OF THE SOUTH WITHIN THE NEXT HOUR OR TWO. THERE IS STILL A CHANCE THAT ADDITIONAL THUNDERSTORMS COULD DEVELOP LATER TONIGHT AS WE REMAIN IN AN UNSETTLED MID/UPPER LEVEL FLOW PATTERN AND A WARM FRONT LIFTS NORTH ACROSS THE AREA. HOWEVER...CONFIDENCE STILL REMAINS LOW...SO I HAVE CONTINUED THE PROB 30 GROUP FOR LATE TONIGHT AFTER 09 UTC. SOUTH-SOUTHWEST WINDS WILL BE FAIRLY STRONG TOMORROW...WITH GUSTS UP AROUND 20 KT THROUGH THE DAY AS LOW PRESSURE MOVES ACROSS THE UPPER MIDWEST. CHANCES FOR CONVECTION WILL INCREASE THURSDAY NIGHT INTO FRIDAY MORNING AS A COLD FRONT APPROACHES THE AREA. KJB //ORD AND MDW CONFIDENCE...UPDATED 03Z... * LOW-MEDIUM CONFIDENCE ON SHRA/TSRA THURSDAY MORNING. * MODERATE CONFIDENCE IN WINDS ON THURSDAY. KJB //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY IN THE AFTERNOON. SATURDAY THROUGH TUESDAY...VFR. WX NIL. KJB && .MARINE... 256 PM CDT AN AREA OF LOW PRESSURE CENTERED OVER THE DAKOTAS IS TO WEAKEN SLIGHTLY AS IT TRACKS NORTHEAST TO SOUTHERN CANADA BY MIDDAY THURSDAY. THE LOW THEN DEEPENS FRIDAY AND MOVES ACROSS JAMES BAY. AN ASSOCIATED COLD FRONT WILL MOVE SOUTHEASTWARD AND ACROSS LAKE MI DURING FRIDAY SHIFTING SOUTH AND SOUTHWESTERLY WINDS TO OUT OF THE WEST AND NORTHWEST AND INCREASING TO STRONG BREEZES. AS LARGE HIGH PRESSURE BUILDS SOUTHEASTWARD ACROSS THE WESTERN GREAT LAKES FRIDAY THROUGH SUNDAY WINDS WILL GRADUALLY RELAX AS THEY VEER THROUGH NORTH AND EAST TO SOUTHEAST. TRS && .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
642 PM CDT WED SEP 18 2013 .DISCUSSION... 336 PM CDT MAIN CHALLENGES/CONCERNS THIS FORECAST PERIOD ARE WITH SHOWERS AND THUNDERSTORMS IN THE NEAR TERM...POSSIBLE PERSISTENT SHOWERS/THUNDERSTORMS OVERNIGHT...AS WELL AS BETTER CHANCES FOR SHOWERS/THUNDERSTORMS THURSDAY NIGHT INTO FRIDAY MORNING. CONTINUE TO MONITOR AREA OF SHOWERS AND THUNDERSTORMS ACROSS NORTH CENTRAL ILLINOIS THAT HAVE CONTINUED TO SLOWLY MOVE EAST TODAY. LATEST RADAR IMAGERY DEPICTING A CONTINUED DEVELOPING TREND IN BOTH COVERAGE AND INTENSITY WITH THIS AREA OF PRECIPITATION...AND EXPECT THIS TO CONTINUE THROUGH THE AFTERNOON AND EARLY EVENING. MCV IS THE MAIN DRIVING FORCE FOR THESE SHOWERS/THUNDERSTORMS...WITH LATEST RAP ANALYSIS SHOWING LOWERING CIN AND AN AXIS OF 1000 J/KG OF SB CAPE EXTENDING INTO NORTHEAST ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH NOT THE GREATEST...THESE CONDITIONS WILL BE ENOUGH TO HELP THIS PRECIP TO HOLD TOGETHER WHILE IT SLOWLY MOVES THROUGH NORTHEAST ILLINOIS THIS AFTERNOON AND THEN NORTHWEST INDIANA THROUGH EARLY EVENING. ALTHOUGH WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED...A PORTION OF THESE STORMS ALONG THE I-80 CORRIDOR HAVE EXHIBITED SOME STRENGTHENING TRENDS WITH BRIEF HIGHER WIND SIGNATURES. SO FOR THIS AFTERNOON/EARLY EVENING...EXPECT ANY OF THE STRONGER STORMS IN THIS GENERAL AREA TO BE CAPABLE OF PRODUCING SPORADIC WIND GUSTS TO 50 MPH...CONTINUOUS LIGHTNING...AND BRIEF HEAVY RAINFALL WITH AN OUTSIDE POSSIBILITY OF AN ISOLATED SEVERE WIND THREAT. WITH THE DEPARTURE OF THESE THUNDERSTORMS...MOST OF THE CWA SHOULD OBSERVE A LULL IN PRECIP BEFORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ONCE AGAIN OVER NIGHT. SEVERAL WEAK MID LEVEL FEATURES WILL CONTINUE TO TRAVERSE CURRENT ZONAL FLOW OVERHEAD...WITH LOW/MID LEVEL FLOW VEERING OVERNIGHT. AS THIS OCCURS...IT APPEARS AS BETTER WAA WILL ORIENT ITSELF MORE TOWARDS NORTHERN ILLINOIS. ALTHOUGH CONFIDENCE IS NOT THE GREATEST FOR COVERAGE TONIGHT...DID MAINTAIN LOW CHANCE POPS FOR MOST AREAS MAINLY AFTER MIDNIGHT OWING TO THIS POTENTIAL. WHATEVER DOES DEVELOP SHOULD BE MORE SCATTERED IN NATURE...AND THEN BEGIN SHIFTING EAST OUT OF THE CWA WHILE DIMINISHING EARLY THURSDAY MORNING. WITH BROAD SOUTHWESTERLY FLOW PERSISTING ON THURSDAY AND A FAIRLY MOIST ENVIRONMENT OVERHEAD...SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE. ALTHOUGH...CHANCES FOR PRECIPITATION SHOULD REMAIN LOW WITH ONCE AGAIN ANYTHING THAT DOES DEVELOP REMAINING SCATTERED. WITH THIS PERSISTENT WAA...CONTINUED WARMUP WILL CONTINUE ON THURSDAY. MADE LITTLE ADJUSTMENTS TO MAX TEMPS FOR THURSDAY KEEPING UPPER 80S FOR MOST LOCATIONS...WITH SOME UNCERTAINTIES TO PRECIP AND EVEN CLOUD COVER REMAINING. IF ENOUGH CLEARING OCCURS...THERMO PROFILES WILL BE SUPPORTIVE OF SOME LOCATIONS REACHING OR SLIGHTLY EXCEEDING 90 DEGREES. MAIN FOCUS FOR THUNDERSTORM DEVELOPMENT SHIFTS TOWARDS THE LATE AFTERNOON AND EARLY EVENING WITH AN APPROACHING TROUGH OF LOW PRESSURE AND COLD FRONT. AS LARGE VORT MAX DROPS SOUTHEAST ACROSS THE NORTHERN PLAINS...SEVERAL WAVES OF ENERGY WILL LIFT NORTHEAST ACROSS THE REGION. THIS WILL HELP TO SHIFT THIS TROUGH/FRONT AS WELL AS INDUCING SOME FURTHER PRESSURE FALLS OUT AHEAD OF IT. WITH POTENTIAL FOR PRE FRONTAL TROUGHINESS TO OCCUR TOMORROW AFTERNOON...SOME GUIDANCE CONTINUES TO DEVELOP PRECIP OUT AHEAD OF THIS FRONT. ALTHOUGH I FEEL THIS IS A BIT OVERDONE...AND HAVE HELD BACK ON POPS FOR THURSDAY DURING THE DAY. HAVE EVEN TRENDED TOWARDS A SLOWER SOLUTION/TREND WITH THIS FRONT/TROUGH WITH BEST CHANCES FOR SHOWERS/THUNDERSTORMS REMAINING OVER WEST/NORTHWEST ILLINOIS FOR MOST OF THURSDAY NIGHT. ITS NOT UNTIL EARLY FRIDAY MORNING THAT THIS FRONT GETS A GOOD SOUTHEAST PUSH WITH BEST FORCING MOVING OVERHEAD. GOOD SWATH OF PRECIP SHOULD SHIFT SOUTHEAST ACROSS THE ENTIRE CWA THROUGH MID DAY FRIDAY...WITH THIS PRECIP THEN EXPECTED TO SHIFT OUT OF THE AREA THROUGH THE AFTERNOON. IT DOES APPEAR AS IF THE STRONGER STORMS SHOULD REMAIN JUST WEST OF THE CWA...BUT WITH SOME POTENTIAL FOR THEM TO REACH THE FAR WESTERN CWA THURSDAY EVENING/NIGHT. IF INSTABILITY CAN INCREASE ON FRIDAY...THERE IS THE POTENTIAL FOR A LINGERING STRONG TO SEVERE THREAT ACROSS THE CWA BEFORE THE STORMS SHIFT OUT OF THE CWA. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 00Z... * CURRENT TSRA MOVING OUT OF THE AREA BY 0030 UTC. * LOW CHANCE FOR ADDITIONAL SHRA/TSRA LATE TONIGHT/THURSDAY MORNING. * GUSTY SOUTH-SOUTHWEST WINDS THURSDAY. KJB //DISCUSSION...UPDATED 00Z... THINGS SHOULD BEGIN QUIETING DOWN NOW FOR MUCH OF THE EVENING. THE LAST BATCH OF THUNDERSTORMS...CURRENTLY ASSOCIATED WITH THE ENHANCED FORCING FOR ASCENT WITH THE MID LEVEL VORT/MCV...IS MOVING ACROSS NORTHEASTERN ILLINOIS. ONCE THIS ACTIVITY MOVES EAST EARLY THIS EVENING...SEVERAL HOURS OF QUITE WEATHER LOOKS TO BE ON TAP FOR THE AREA. THE WINDS ARE BIT DISTURBED FROM THE CURRENT CONVECTIVE ACTIVITY...BUT EXPECT WINDS TO QUICKLY COME BACK OUT OF THE SOUTH WITHIN THE NEXT HOUR OR TWO. THERE IS STILL A CHANCE THAT ADDITIONAL THUNDERSTORMS COULD DEVELOP LATER TONIGHT AS WE REMAIN IN AN UNSETTLED MID/UPPER LEVEL FLOW PATTERN AND A WARM FRONT LIFTS NORTH ACROSS THE AREA. HOWEVER...CONFIDENCE STILL REMAINS LOW...SO I HAVE CONTINUED THE PROB 30 GROUP FOR LATE TONIGHT AFTER 09 UTC. SOUTH-SOUTHWEST WINDS WILL BE FAIRLY STRONG TOMORROW...WITH GUSTS UP AROUND 20 KT THROUGH THE DAY AS LOW PRESSURE MOVES ACROSS THE UPPER MIDWEST. CHANCES FOR CONVECTION WILL INCREASE THURSDAY NIGHT INTO FRIDAY MORNING AS A COLD FRONT APPROACHES THE AREA. KJB //ORD AND MDW CONFIDENCE...UPDATED 00Z... * LOW CONFIDENCE ON SHRA/TSRA THURSDAY MORNING. * MODERATE CONFIDENCE IN WINDS ON THURSDAY. KJB //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY IN THE AFTERNOON. SATURDAY THROUGH TUESDAY...VFR. WX NIL. KJB && .MARINE... 256 PM CDT AN AREA OF LOW PRESSURE CENTERED OVER THE DAKOTAS IS TO WEAKEN SLIGHTLY AS IT TRACKS NORTHEAST TO SOUTHERN CANADA BY MIDDAY THURSDAY. THE LOW THEN DEEPENS FRIDAY AND MOVES ACROSS JAMES BAY. AN ASSOCIATED COLD FRONT WILL MOVE SOUTHEASTWARD AND ACROSS LAKE MI DURING FRIDAY SHIFTING SOUTH AND SOUTHWESTERLY WINDS TO OUT OF THE WEST AND NORTHWEST AND INCREASING TO STRONG BREEZES. AS LARGE HIGH PRESSURE BUILDS SOUTHEASTWARD ACROSS THE WESTERN GREAT LAKES FRIDAY THROUGH SUNDAY WINDS WILL GRADUALLY RELAX AS THEY VEER THROUGH NORTH AND EAST TO SOUTHEAST. TRS && .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 INDIANAPOLIS IN
1014 PM EDT WED SEP 18 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 358 PM EDT WED SEP 18 2013 A BROAD UPPER LEVEL RIDGE TO OUR SOUTH IS BEING ROUNDED BY VERY WEAK AND VERY SUBTLE UPPER LEVEL WAVES...POORLY RESOLVED BY GUIDANCE. THESE WEAK WAVES MAY BE ABLE TO SPARK A SHOWER OR STORM AT TIMES THROUGH LATE THURSDAY NIGHT INTO FRIDAY NIGHT...WHEN THE MAIN FRONTAL SYSTEM WILL PUSH THROUGH THE AREA AND BRING A MORE SUBSTANTIAL OPPORTUNITY FOR STORMS TO THE AREA BEFORE DRY AND COOLER CONDITIONS RETURN FOR THE REMAINDER OF THE FORECAST PERIOD. && .NEAR TERM /REST OF TONIGHT/... ISSUED AT 946 PM EDT WED SEP 18 2013 RADAR LOOP SHOWS SOME STORMS IN NORTHWEST INDIANA WITH A LITTLE SHOWER ALSO OVER NORTHERN CARROLL COUNTY. THE LARGER AREA OF STORMS IS MOVING SOUTHEAST. LOOKING AT HRRR MODEL OUTPUT IT APPEARS THAT THIS WILL WEAKEN AS IT HEADS THIS WAY SIMILAR TO THE ECHOES THAT ARE NOW ONLY A BRIEF SHOWER. STILL IT LOOKS POSSIBLE THAT STORMS COULD REACH THE NORTHERN COUNTIES OF THE AREA OVER THE NEXT FEW HOURS AND THUS WENT WITH A SLIGHT TO LOW END CHANCE THERE DURING THIS TIME. ALSO SEEING SOME LIGHT RAIN OVER CENTRAL ILLINOIS PROMPTED BY A WEAK UPPER WAVE AND SOME ISENTROPIC LIFT AND THIS COULD MOVE INTO THE AREA AFTER 6Z...SO WENT WITH A SLIGHT CHANCE ACROSS ALL OF CENTRAL INDIANA THEN. THIS SHOULD ALSO COVER SOME REDEVELOPMENT OVER THE NORTHEASTERN COUNTIES THAT THE HRRR IS SHOWING...ALTHOUGH CONFIDENCE IN THIS SOLUTION IS LOW AND THUS NO HIGHER THAN 20 POPS WILL BE USED DURING THAT TIME. GOING LOW TEMPERATURES IN THE MIDDLE 60S LOOK GOOD BASED ON EXPECTED CLOUD COVER AND CURRENT TEMPERATURES. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... ISSUED AT 358 PM EDT WED SEP 18 2013 MAY SEE SOME SHOWERS OR STORMS DEVELOP FROM MIDDAY ONWARD TOMORROW...AGAIN NO MORE THAN SCATTERED IN NATURE. HIGHER POPS ARE ONLY MERITED FRIDAY INTO FRIDAY NIGHT AS THE FRONT FINALLY PUSHES THROUGH THE AREA. SPC SEE TEXT OUTLOOK DAY 3 APPEARS REASONABLE GIVEN THE TIME OF DAY THE FRONT IS EXPECTED...BUT INSTABILITY AND SHEAR ARE MODEST AT BEST AND DO NOT EXPECT MUCH MORE THAN ISOLATED SEVERE IF THAT. ON TEMPS...CONSENSUS NUMBERS LOOKED OK THROUGHOUT GIVEN EXPECTED THICKNESSES AND PRECIP COVERAGE...EXCEPT FOR SATURDAY WHERE A WARMER MOS BLEND WAS PREFERRED WITH SKIES LIKELY TO CLEAR AND AMPLE SUN EXPECTED. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... ISSUED AT 220 PM EDT WED SEP 18 2013 DRY FORECAST THIS PERIOD WITH SEASONABLE TEMPERATURES. GFS AND ECMWF DEPICT A CUT OFF UPPER LOW MOVING THROUGH THE APPALACHIANS EARLY IN THE PERIOD WHILE RIDGING ALOFT AND STRONG SUBSIDENCE OVER THE MISSISSIPPI RIVER VALLEY PROVIDES A NORTHERLY FLOW OF AIR AS IT SLOWLY BUILDS EAST DURING THE PERIOD. AS THE RIDGE MOVES EAST OVER INDIANA BY THE MIDDLE OF NEXT WEEK...TEMPS WILL SLOWLY MODERATE TO SLIGHTLY ABOVE NORMAL AS RETURN FLOW BEGINS. && .AVIATION /DISCUSSION FOR THE 190000Z TAFS/... ISSUED AT 1013 PM EDT WED SEP 18 2013 0215Z UPDATE...VERY LITTLE CHANGE NEEDED TO THE TAFS ATTM. PREV DISC FOLLOWS. VFR CONDITIONS EXPECTED THIS EVENING. MVFR CONDITIONS WILL BE POSSIBLE LATE TONIGHT EARLY THU MORNING. A RETURN TO VFR IS EXPECTED LATE ON THURSDAY MORNING. AS HEATING IS LOST THIS EVENING...OVERALL COVERAGE OF PRECIPITATION TO THE WEST SHOULD DIMINISH. MODELS HINT AT LOWERING CIGS AND VISIBILITIES DIURNALLY TONIGHT AS HIGH DEW POINTS AND DIURNAL COOLING IS ONGOING. MODELS ONCE AGAIN HINT AT ANOTHER BIT OF LIFT PUSHING THROUGH THE AREA ON LATE THURSDAY AFTERNOON...HOWEVER...CONFIDENCE IN THIS WEAK FEATURES REMAIN LOW AND WILL STICK WITH VFR AND VCSH ATTM. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...NIELD NEAR TERM...CP SHORT TERM...NIELD LONG TERM....PUMA AVIATION...SMF VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
953 PM EDT WED SEP 18 2013 .UPDATE... THE NEAR TERM SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 358 PM EDT WED SEP 18 2013 A BROAD UPPER LEVEL RIDGE TO OUR SOUTH IS BEING ROUNDED BY VERY WEAK AND VERY SUBTLE UPPER LEVEL WAVES...POORLY RESOLVED BY GUIDANCE. THESE WEAK WAVES MAY BE ABLE TO SPARK A SHOWER OR STORM AT TIMES THROUGH LATE THURSDAY NIGHT INTO FRIDAY NIGHT...WHEN THE MAIN FRONTAL SYSTEM WILL PUSH THROUGH THE AREA AND BRING A MORE SUBSTANTIAL OPPORTUNITY FOR STORMS TO THE AREA BEFORE DRY AND COOLER CONDITIONS RETURN FOR THE REMAINDER OF THE FORECAST PERIOD. && .NEAR TERM /REST OF TONIGHT/... ISSUED AT 946 PM EDT WED SEP 18 2013 RADAR LOOP SHOWS SOME STORMS IN NORTHWEST INDIANA WITH A LITTLE SHOWER ALSO OVER NORTHERN CARROLL COUNTY. THE LARGER AREA OF STORMS IS MOVING SOUTHEAST. LOOKING AT HRRR MODEL OUTPUT IT APPEARS THAT THIS WILL WEAKEN AS IT HEADS THIS WAY SIMILAR TO THE ECHOES THAT ARE NOW ONLY A BRIEF SHOWER. STILL IT LOOKS POSSIBLE THAT STORMS COULD REACH THE NORTHERN COUNTIES OF THE AREA OVER THE NEXT FEW HOURS AND THUS WENT WITH A SLIGHT TO LOW END CHANCE THERE DURING THIS TIME. ALSO SEEING SOME LIGHT RAIN OVER CENTRAL ILLINOIS PROMPTED BY A WEAK UPPER WAVE AND SOME ISENTROPIC LIFT AND THIS COULD MOVE INTO THE AREA AFTER 6Z...SO WENT WITH A SLIGHT CHANCE ACROSS ALL OF CENTRAL INDIANA THEN. THIS SHOULD ALSO COVER SOME REDEVELOPMENT OVER THE NORTHEASTERN COUNTIES THAT THE HRRR IS SHOWING...ALTHOUGH CONFIDENCE IN THIS SOLUTION IS LOW AND THUS NO HIGHER THAN 20 POPS WILL BE USED DURING THAT TIME. GOING LOW TEMPERATURES IN THE MIDDLE 60S LOOK GOOD BASED ON EXPECTED CLOUD COVER AND CURRENT TEMPERATURES. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... ISSUED AT 358 PM EDT WED SEP 18 2013 MAY SEE SOME SHOWERS OR STORMS DEVELOP FROM MIDDAY ONWARD TOMORROW...AGAIN NO MORE THAN SCATTERED IN NATURE. HIGHER POPS ARE ONLY MERITED FRIDAY INTO FRIDAY NIGHT AS THE FRONT FINALLY PUSHES THROUGH THE AREA. SPC SEE TEXT OUTLOOK DAY 3 APPEARS REASONABLE GIVEN THE TIME OF DAY THE FRONT IS EXPECTED...BUT INSTABILITY AND SHEAR ARE MODEST AT BEST AND DO NOT EXPECT MUCH MORE THAN ISOLATED SEVERE IF THAT. ON TEMPS...CONSENSUS NUMBERS LOOKED OK THROUGHOUT GIVEN EXPECTED THICKNESSES AND PRECIP COVERAGE...EXCEPT FOR SATURDAY WHERE A WARMER MOS BLEND WAS PREFERRED WITH SKIES LIKELY TO CLEAR AND AMPLE SUN EXPECTED. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... ISSUED AT 220 PM EDT WED SEP 18 2013 DRY FORECAST THIS PERIOD WITH SEASONABLE TEMPERATURES. GFS AND ECMWF DEPICT A CUT OFF UPPER LOW MOVING THROUGH THE APPALACHIANS EARLY IN THE PERIOD WHILE RIDGING ALOFT AND STRONG SUBSIDENCE OVER THE MISSISSIPPI RIVER VALLEY PROVIDES A NORTHERLY FLOW OF AIR AS IT SLOWLY BUILDS EAST DURING THE PERIOD. AS THE RIDGE MOVES EAST OVER INDIANA BY THE MIDDLE OF NEXT WEEK...TEMPS WILL SLOWLY MODERATE TO SLIGHTLY ABOVE NORMAL AS RETURN FLOW BEGINS. && .AVIATION /DISCUSSION FOR THE 190000Z TAFS/... ISSUED AT 711 PM EDT WED SEP 18 2013 VFR CONDITIONS EXPECTED THIS EVENING. MVFR CONDITIONS WILL BE POSSIBLE LATE TONIGHT EARLY THU MORNING. A RETURN TO VFR IS EXPECTED LATE ON THURSDAY MORNING. AS HEATING IS LOST THIS EVENING...OVERALL COVERAGE OF PRECIPITATION TO THE WEST SHOULD DIMINISH. MODELS HINT AT LOWERING CIGS AND VISIBILITIES DIURNALLY TONIGHT AS HIGH DEW POINTS AND DIURNAL COOLING IS ONGOING. MODELS ONCE AGAIN HINT AT ANOTHER BIT OF LIFT PUSHING THROUGH THE AREA ON LATE THURSDAY AFTERNOON...HOWEVER...CONFIDENCE IN THIS WEAK FEATURES REMAIN LOW AND WILL STICK WITH VFR AND VCSH ATTM. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...NIELD NEAR TERM...CP SHORT TERM...NIELD LONG TERM....PUMA AVIATION...SMF VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
855 PM CDT WED SEP 18 2013 .UPDATE... ISSUED AT 847 PM CDT WED SEP 18 2013 AN UPDATE WAS JUST SENT TO INCREASE POPS OVER THE NORTH HALF OF THE AREA AFTER MIDNIGHT. LLJ PROGGED TO STRENGTHEN TO 40+KTS LATE TONIGHT AND IS POINTED AT NORTHEAST IOWA DURING THE EARLY MORNING HOURS. SATELLITE IMAGERY IS SHOWING AN AREA OF MID CLOUDS DRIFTING EAST THROUGH NORTH CENTRAL IA AND THEY SHOULD BE OVER THE NE QUARTER OF THE STATE BY MIDNIGHT...WHERE THE NOSE OF THE LLJ IS AIMED. THE PAST SEVERAL RUNS OF THE HRRR HAVE BEEN CONSISTENTLY DEVELOPING CONVECTION IN THE SAME AREA. GIVEN THESE FACTORS THERE WAS ENOUGH CONFIDENCE TO INCREASE POPS INTO THE CHANCE CATEGORY BETWEEN 06Z AND 12Z. DLF && .SYNOPSIS... ISSUED AT 310 PM CDT WED SEP 18 2013 12Z UA ANALYSIS HAD AN 850MB LOW NEAR KBIS WITH A DEVELOPING WARM FRONT RUNNING SOUTHEAST TO KSTL. A LLJ RAN FROM WEST TEXAS INTO SOUTHWEST IOWA AND DEW POINTS WERE IN THE MID TEENS FROM MEXICO INTO SOUTHERN MINNESOTA. SATELLITE/RADAR TRENDS SHOW THE SMALL COMPLEX OF STORMS MOVING INTO NORTHEAST IOWA WITH GENERALLY CLEAR SKIES ACROSS THE PLAINS AND IOWA. 18Z SFC ANALYSIS HAS A LOW NEAR KPIR WITH A WARM FRONT RUNNING SOUTHEAST TO NEAR KMLI AND THEN SOUTH TO NEAR K3LF. RAIN COOLED AIR REMAINED ACROSS NORTHEAST IOWA AND NORTHWEST ILLINOIS. DEW POINTS WERE IN THE 60S ACROSS THE MIDWEST WITH POCKETS OF 70S IN THE SOUTHERN PLAINS. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 310 PM CDT WED SEP 18 2013 SATELLITE TRENDS INDICATE LITTLE IN THE WAY OF NEW CLOUDS HAVE FORMED DURING THE AFTERNOON SO THE THREAT OF NEW CONVECTION PRIOR TO SUNSET IS VERY LOW. THE MCS AND LIFT TOOLS ARE SUGGESTING SOME ISOLATED WEAK CONVECTION MAY DEVELOP OVER THE AREA BY LATE EVENING AND MOVE EAST. HOWEVER...THE BETTER FORCING/MOISTURE IS WEST OF THE AREA. THE MCS AND LIFT TOOLS ARE SUGGESTING ANOTHER STORM COMPLEX DEVELOPING ALONG THE IA/MO BORDER LATE TONIGHT AND POSSIBLY ARRIVING IN THE WESTERN CWFA AROUND SUNRISE THURSDAY. THUS MOST OF THE AREA SHOULD SEE DRY CONDITIONS TONIGHT. IF THE STORM COMPLEX DEVELOPS AS SUGGESTED ALONG THE IA/MO BORDER...THEN THIS COMPLEX WOULD MOVE ACROSS THE WESTERN HALF OF THE CWFA DURING THE MORNING. CLOUD COVER/PRECIPITATION MAY MAKE IT DIFFICULT TO ACHIEVE HIGHS IN THE MID AND UPPER 80S THURSDAY. NEW CONVECTION IS EXPECTED TO DEVELOP THURSDAY AFTERNOON AHEAD OF THE APPROACHING COLD FRONT. MOISTURE LEVELS IN THE ATMOSPHERE ARE PROJECTED TO BE QUITE HIGH UP INTO THE MID LEVELS. THUS THE POTENTIAL FOR ANY SEVERE STORMS APPEARS TO BE LOW. ..08.. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 310 PM CDT WED SEP 18 2013 MODERATE TO HEAVY RAIN EVENT THURSDAY NIGHT...THEN SEASONABLY COOL. OVERVIEW...INITIALIZATION AND VERIFICATION AVERAGE WITH MOST SOLUTIONS UNDERPLAYING MOISTURE IN CENTRAL PLAINS AND SW MONSOON PLUME. PACIFIC ENERGY IS ALSO UNDERPLAYED WITH 10 TO 20 METER HEIGHT FALLS UNDERDONE. THIS SHOWS UP IN SURFACE PRESSURE FIELDS. VERIFICATION AT 18Z SUPPORTS FORCING OF HI-RES ECMWF/UKMET AND NAM-WRF WITH HI- RES ECMWF CLOSEST ON MOISTURE FLUX WITH COOL FRONT PASSING THURSDAY NIGHT. THEN...EARLY FALL HIGH PRESSURE TO BRING SEVERAL DAYS OF NICE LATE SEPTEMBER WEATHER WITH LOW HUMIDITY. THURSDAY NIGHT...STRAIGHTFORWARD FORECAST. PW/S OF 1.5" OF DEEP MOISTURE AHEAD OF DEEP SURFACE AND UPPER LEVEL TROUGH TO BRING A LARGE SWATH OF SHOWERS AND THUNDERSTORMS. LITTLE OR NO SURFACE WAVE SUGGESTED AT THIS TIME...LOCAL TOOLS INDICATE ALMOST ALL THE AREA TO PICK UP .5 TO LOCALLY NEAR 1.5 INCHES OF RAIN. WENT WITH 80-90 POPS WITH FRONT PASSING BETWEEN MIDNIGHT AND 7 AM. DEEP MOISTURE...OVERNIGHT FORCING AND HIGH FREEZING LEVELS DO NOT SUPPORT A SEVERE RISK AT THIS TIME WITH STRONGEST STORMS PRODUCING MAYBE 30-40 MPH WINDS. LATER SHIFTS WILL NEED TO REASSESS AS NAM- WRF IS TOO UNSTABLE IN BL AS HAS BEEN MORE OFTEN THE CASE THIS WARM SEASON. NOTE: IF A WAVE FORMS...LOCALLY 2+ INCH AMOUNTS WILL BE POSSIBLE. FRIDAY...KEPT MORNING POPS EAST SECTIONS WITH CLEARING BY MID DAY AND BREEZING NW WINDS OF 10-20+ MPH. HIGHS MOSTLY 70-75F FOR A NICE DAY. FRIDAY NIGHT THROUGH WEDNESDAY...MOSTLY FAIR AND SLIGHTLY BELOW NORMAL TEMPERATURES AS CANADIAN HIGH PRESSURE DOMINATES. HIGHS GENERALLY UPPER 60S TO MIDDLE 70S WITH LOWS 45 TO 55 DEGREES. GOOD WEATHER FOR MOST OUTDOOR ACTIVITIES. ANOTHER PROMISING RAIN EVENT POSSIBLE BY LATE IN THE WEEK. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 632 PM CDT WED SEP 18 2013 THE MAIN CONCERN WILL BE THE THUNDERSTORM POTENTIAL OVERNIGHT. THERE ARE STILL INDICATIONS OF A THUNDERSTORM COMPLEX DEVELOPING TO OUR WEST LATE TONIGHT AND MOVING EAST THROUGH THE AREA THURSDAY MORNING. IT APPEARS THE BETTER FORCING WILL BE NORTH OF I80 SO LIMITED THE MENTION OF THUNDER TO THE CID AND DBQ TAFS BETWEEN 10Z AND 14Z. OTHERWISE EXPECT MAINLY VFR CONDITIONS OVERNIGHT THURSDAY. A COLD FRONT WILL BE APPROACHING THE AREA THURSDAY AFTERNOON. THUNDERSTORMS AHEAD OF THE FRONT COULD REACH CID AND DBQ AS EARLY AS LATE THURSDAY AFTERNOON. IFR/MVFR CONDITIONS WOULD ACCOMPANY THE STORMS. ALSO SOUTHWEST WINDS AHEAD OF THE FRONT WILL GUST TO 20 TO 25KTS DURING THE AFTERNOON. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ UPDATE...DLF SYNOPSIS...08 SHORT TERM...08 LONG TERM...NICHOLS AVIATION...DLF
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1132 PM CDT MON SEP 16 2013 .UPDATE... ISSUED AT 1130 PM CDT MON SEP 16 2013 MIDWEST DOPPLER RADARS WERE INDICATING AN AREA OF INCREASING SHOWERS ALONG THE MO RIVER VALLEY FROM SE NEB/SW IA AND INTO EXTREME NW MO LATE THIS EVENING. WARM AIR ADVECTION WAS KICKING IN AS THE NOCTURNAL LOW LEVEL JET INTENSIFIES IN THE SOUTHERN PLAINS. ACROSS THE DVN CWA THE CIRRUS SHIELD CONTINUED TO EXPAND NORTHEASTWARD AS THE GREAT LAKES HIGH PRESSURE SYSTEM SLOWLY SHIFTS EAST. TEMPERATURES HAVE ALREADY DIPPED INTO THE UPPER 40S IN NW IL WITH MID TO UPPER 50S COMMON ELSEWHERE. THE 00Z SUBJECTIVE UPPER AIR ANALYSIS INDICATED A VERY DRY AIRMASS FROM ABOUT THE MS RIVER VALLEY EASTWARD INTO THE GREAT LAKES. 850 MB DEWPOINTS WERE -10C AT KDVN...-18C AT KMPX...AND -23C AT KDTX. WEST OF THE RIDGE AXIS COPIOUS MOISTURE WAS FOUND IN THE PLAINS. 850 MB DEWPOINTS WERE 14C AT KTOP AND IN THE RANGE OF 14 TO 17C FROM SOUTHERN/WESTERN TX INTO OK. PRECIPITABLE WATERS WERE 150 TO 180 PERCENT OF NORMAL FOR MID SEPTEMBER IN THE PLAINS. THE RAPID REFRESH/NAM THIS EVENING BRING IN A FEW LIGHT SHOWERS OR SPRINKLES INTO OUR FAR SW CWA TOWARDS MORNING SO HAVE LEFT SMALL POPS AS IS. HAVE ALREADY ADJUSTED SKY GRIDS BUT HAVE LEFT TEMPERATURES ALONE FOR NOW. UPDATE ISSUED AT 630 PM CDT MON SEP 16 2013 CIRRUS SHIELD CONTINUES TO SPILL INTO THE SOUTHWEST HALF OF THE CWA BUT THINS AS IT RUNS INTO THE DRY AIR FARTHER TO THE NORTHEAST... WITH HIGH PRESSURE SITUATED ACROSS THE GREAT LAKES REGION. WILL MONITOR THIS EVENING THE TEMPERATURE AND CLOUD TRENDS AND ADJUST IF NEEDED. && .SYNOPSIS... ISSUED AT 317 PM CDT MON SEP 16 2013 LATEST SFC ANALYSIS WAS INDICATING HIGH PRESSURE DOMINATING THE WESTERN GRT LKS AND UPPER MS RVR VALLEY. SUBSIDENCE FROM THE HEART OF THIS FEATURE AND UPPER LEVEL RIDGING HELPING ERODE STRATOCU FIELDS IN THE CWA...BUT SOME CLOUD FIELDS HOLDING FIRM ACRS SOUTH CENTRAL INTO SOUTHEASTERN IA. ALOFT...WATER VAPOR IMAGERY WAS INDICATING LINGERING MONSOONAL MOISTURE FIELDS ACRS THE CENTRAL PLAINS OVER TO THE OH RVR/TN VALLEY REGIONS...WHILE MOISTURE OFF INGRID SURGES INLAND ACRS MEX/SOUTHERN TX. UPSTREAM WAVE NOTED ACRS THE NORTHWEST PLAINS ON WESTERN FLANK OF UPPER RIDGE AXIS. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 317 PM CDT MON SEP 16 2013 TONIGHT...WILL FOLLOW LATEST RAP LLVL MOISTURE/RH GUIDANCE WHICH SUGGESTS A CONTINUED CLEARING OF THE STRATOCU EXCEPT MAYBE THE FAR SOUTHWESTERN CWA THROUGH THIS EVENING. IT ALSO SUGGESTS LLVL FLOW TO VEER TO THE EAST-SOUTHEAST OVERNIGHT AND POSSIBLY START ADVECTING MORE HIGHER RH LEVELS/STRATOCU FROM SOUTHEAST IL/IND LATE TONIGHT AFTER MIDNIGHT. FOR NOW WILL MAINTAIN MOSTLY CLR SKIES OVERNIGHT FOR BULK OF THE EASTERN HALF OF THE CWA AND BANK ON COOL LOWS IN THE 40S WITH LOW/DRY AMBIENT SFC DPTS. BUT SOME BUST POTENTIAL ON THE LOW SIDE IF THE CLOUDS DO ADVECT IN FROM THE EAST LATER TONIGHT ALONG WITH HIGHER DPTS FROM THOSE SAME AREAS. WILL KEEP LOWS IN THE LOW TO MID 50S IN THE SOUTHWEST THIRD WITH EXPECTED MID DECK/HIGHER CLOUD INCREASE LATER TONIGHT FROM THE SOUTHWEST IN THOSE AREAS. ELEVATED WARM AIR ADVECTION PROCESSES ASSOCIATED WITH RIDGE-RIDING WAVE MENTIONED ABOVE PUSHING ACRS EASTERN NEB AND WESTERN IA TO TAP IN THE LINGERING MONSOONAL MOISTURE AND PRODUCE SHOWERS OVERNIGHT...BUT RIDGING AND DRY AIR IN PLACE TO MAKE FOR MOST OF THE CWA REMAINING DRY THROUGH 12Z TUE. MUCH OF INITIAL LIFT FROM APPROACHING UPPER WAVE TO GO INTO TOP-DOWN SATURATION PROCESSES WITH VIRGA TO LIGHT SHOWERS/SPRINKLES ACRS THE SOUTHWEST THIRD TOWARD DAYBREAK. TUESDAY...DESPITE SOME DECENT MODEL INDICATED ELEVATED THTA-E ADVECTION AND CONVERGENT REGIONS PUSHING ACRS THE SOUTHWESTERN THIRD TO HALF OF THE DVN CWA AS THE DAY PROGRESSES...THE BATTLE WILL BE ON WITH LARGE DRY AIRMASS TO THE EAST. LIKE THE PREVIOUS SHIFT MENTIONED...SHARP MOISTURE AND PRECIP GRADIENTS MAY DEVELOP LOCALLY WITH SOME AREAS/IN THE FAR SOUTHWEST/ GETTING UP TO A QUARTER INCH OF RAIN BY MID AFTERNOON...AND AREAS EAST OF THE MS RVR ESPECIALLY EAST CENTRAL AND NORTHEAST REMAINING DRY THROUGH 00Z WED. WILL SPREAD IN POPS GENERALLY FROM WEST-SOUTHWEST TO EAST IN DECREASING FASHION TUE. BUT SOME AREAS PROBABLY WARRANT CATEGORICAL POPS WEST OF THE MS RVR. EXPECT MAINLY SHOWERS IN DECLINING FASHION AS THEY SPREAD EASTWARD AND ENCOUNTER THE DRY AIR...BUT PROGGED MID LEVEL MUCAPES OF 200-500 J/KG IF CORRECT...SUPPORTS ISOLATED EMBEDDED THUNDER IN THE SOUTHWESTERN HALF ON TUE. TEMPS WILL BE A CHALLENGE TUE DEPENDING ON CLOUD COVER AND EVAPO-COOLING FROM PRECIP. WILL GO WITH COOLER VALUES HELD DOWN IN THE 60S IN THE WEST WITH EARLIER ARRIVAL OF CLOUDS AND PRECIP...WARMER IN THE LOW 70S EAST OF THE MS RVR. ..12.. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 317 PM CDT MON SEP 16 2013 ACTIVE WX WILL BE SEEN ACROSS THE MIDWEST FOR THE REMAINDER OF THE WORK WEEK WITH SEVERAL CHANCES FOR RAIN. RAIN THAT MOVES INTO THE AREA TUESDAY AFTERNOON WILL OVERSPREAD THE AREA TUESDAY NIGHT/WED. AS THE OVERALL FORCING WEAKENS ON WEDNESDAY THE AREAL COVERAGE OF PRECIPITATION WILL DECREASE WEDNESDAY AFTERNOON. WED NIGHT/THURSDAY THE NEXT ROUND OF FORCING MOVES THROUGH THE AREA HELPING TO RE-DEVELOP NEW CONVECTION. A RESPECTABLE LLJ DEVELOPS WED NIGHT WHICH SHOULD RESULT IN CONSIDERABLE NOCTURNAL CONVECTION AFTER MIDNIGHT AND INTO THURSDAY MORNING. THE APPROACHING COLD FRONT ON THURSDAY IS EXPECTED TO HELP MAINTAIN CONVECTION DURING THE AFTERNOON. THE AMOUNT OF CLOUD COVER MAY HOLD DOWN TEMPERATURES SOMEWHAT BUT THEY SHOULD STILL BE CLOSE TO NORMAL. THURSDAY NIGHT ON... THE MODEL CONSENSUS HAS HIGH CHC/LIKELY POPS FOR THURS NIGHT AS THE NEXT FRONT MOVES THROUGH THE AREA. THE FRONT WILL CLEAR THE AREA ON FRIDAY SO ONLY SCHC/LOW CHC POPS ARE GIVEN BY THE MODEL CONSENSUS FOR THE EASTERN HALF OF THE CWFA. COOL CANADIAN HIGH BUILDS INTO THE GREAT LAKES FOR FRIDAY NIGHT THROUGH SUNDAY NIGHT. THE MODEL CONSENSUS GIVES DRY CONDITIONS WITH TEMPERATURES AVERAGING BELOW NORMAL. SOUTHERLY FLOW DEVELOPING ON MONDAY WILL ALLOW TEMPERATURES TO AGAIN WARM. THE MODEL CONSENSUS HAS DRY CONDITIONS FOR MONDAY WITH CHC POPS FOR MONDAY NIGHT. ..08.. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1130 PM CDT MON SEP 16 2013 VFR CONDS THROUGH MOST OF THIS TAF CYCLE. WILL SPREAD LIGHT RAIN AND SPRINKLES TO KCID/KMLI/KBRL TUESDAY AFTERNOON BUT VSBYS SHOULD REMAIN P6SM. EAST WINDS 5 TO 10 KNOTS TONIGHT THEN SOUTHEAST AROUND 10 KNOTS TUESDAY AND TUESDAY EVENING. SHOWERS AND SCATTERED THUNDERSTORMS WILL BEGIN TO INCREASE TUESDAY EVENING AS ELEVATED INSTABILITY INCREASES WITH THE RETURN OF DEEPER MOISTURE. CIGS SHOULD ALSO LOWER TO MVFR CATEGORY TUESDAY EVENING...ESPECIALLY AT KCID/KBRL. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ UPDATE...HAASE SYNOPSIS...12 SHORT TERM...12 LONG TERM...08 AVIATION...HAASE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1142 PM MDT MON SEP 16 2013 .UPDATE... ISSUED AT 637 PM MDT MON SEP 16 2013 JUST COMPLETED AN EXTENSIVE UPDATE. MODELS PLAYING CATCHUP. SINCE IT DID NOT CLEAR OFF...TEMPERATURES ARE STARTING OUT MUCH COOLER THAN WHAT THE MODELS THINK. FOG HAS ALREADY DEVELOPED AND EXPECT IT TO CONTINUE AS LOW LEVEL WIND FIELD WILL CONTINUE TO ADVECT IN HIGHER DEWPOINTS. SO THROUGH TOMORROW MORNING HAVE INTRODUCED WIDESPREAD FOG AND DRIZZLE. THE RUC IS CATCHING THIS THE BEST RIGHT NOW WITH THE NAM/ECMWF NOT TOO FAR BEHIND. CONSEQUENTLY ADJUSTED THE CLOUD COVER AND THE WIND FIELD...WHICH THE RUC IS DOING THE BEST ON...AS WELL. ALSO CURRENT TEMPERATURES WERE NEAR OR BELOW THE FORECAST MINS SO LOWERED THOSE ACCORDINGLY. THE OTHER MAIN CHANGE WAS THE PRECIPITATION FORECAST. RIGHT NOW NOTHING GOING ON...SO REMOVED THUNDERSTORMS THROUGH MID EVENING...AS ANOTHER SHORTWAVE TROUGH MOVES IN FROM THE WEST. AT THE SAME TIME A RATHER STRONG 700 MB WARM AIR ADVECTION DEVELOPS AS A WEAK RIGHT REAR QUADRANT OF 250 MB JET AFFECTS THE AREA AS WELL. THESE ALL COME TOGETHER AND INCREASE IN STRENGTH AS THE NIGHT GOES ON. THETA-E LAPSE RATES ARE VERY FAVORABLE FOR RESPONSE TO THE LIFT. ELEVATED CAPE INCREASES AS ELEVATED CINH DECREASES. RIGHT NOW THE BEST CHANCE FOR THUNDERSTORMS WILL BE AFTER 06Z AND IN THE EASTERN HALF. WOULD NOT BE SURPRISED IF THUNDERSTORMS BECOME RATHER STRONG CONSIDERING THE AMOUNT OF CAPE AND THE VERY FAVORABLE LAPSE RATES. && .SHORT TERM...(THIS AFTERNOON THROUGH TUESDAY) ISSUED AT 1148 AM MDT MON SEP 16 2013 A COOL HIGH PRESSURE AREA REMAINS IN PLACE OVER THE FORECAST AREA TODAY AS A FEW LIGHT TO MODERATE SHOWERS MOVE NORTHEASTWARD ACROSS THE EASTERN SECTIONS OF THE FORECAST AREA. THESE SHOWERS ARE A RESULT OF A COUPLE OF SHORT WAVE TROUGHS IN THE UPPER FLOW MOVING EAST OF THE ROCKIES AND ACROSS THE CENTRAL HIGH PLAINS REGION THIS AFTERNOON AND EVENING. EXPECT A FEW MORE SHOWERS TO DEVELOP AS A SECOND WEAKER SHORT WAVE TROUGH FOLLOWS IN ITS PATH. BEHIND THOSE WAVES A WEAK RIDGE AND MORE WESTERLY FLOW MOVES EAST OF THE ROCKIES WITH AN AREA OF SUBSIDENCE ACROSS THE FORECAST AREA ON TUESDAY AND A LEE TROUGH THAT DEEPENS ALONG THE FRONT RANGE OF WYOMING AND COLORADO. AS THIS TROUGH DEEPENS...THE HIGH PRESSURE AREA MOVES EAST AND THE MOIST RETURN FLOW BEGINS TO MOVE OUT OF THE REGION TO BE REPLACED BY A DRYER SOUTH TO SOUTHWEST NEAR SURFACE FLOW. LOW CLOUDS AND FOG THAT ARE EXPECTED TO DEVELOP IN THE SATURATED AIR MASS ACROSS THE AREA OVERNIGHT ARE EXPECTED TO DIMINISH BY LATE TUESDAY AFTERNOON AND EVENING WITH A RETURN OF HIGH TEMPERATURES IN THE 80S. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 219 PM MDT MON SEP 16 2013 A SHORTWAVE RIDGE WILL BE OVER THE PLAINS TUESDAY NIGHT FOLLOWED BY WESTERLY FLOW THROUGH THURSDAY AS A TROUGH MOVES ACROSS THE NORTHERN PLAINS. A SURFACE TROUGH WILL EXTEND SOUTH INTO EASTERN COLORADO TUESDAY NIGHT/WEDNESDAY. THIS TROUGH WILL MOVE SOUTHEAST INTO NORTHWEST KANSAS WEDNESDAY NIGHT. HIGH PRESSURE WILL MOVE INTO NORTHWEST KANSAS THURSDAY. CONDITIONS WILL REMAIN DRY TUESDAY NIGHT AND WEDNESDAY DUE TO SUBSIDENCE OVER THE AREA. SOME DYNAMICS MOVE INTO THE AREA WEDNESDAY NIGHT BUT MOISTURE IS NOT IMPRESSIVE SO WILL CONTINUE SLIGHT CHANCE POPS FOR THUNDERSTORMS. DYNAMICS STILL REMAIN OVER THE FA EAST OF THE COLORADO BORDER THURSDAY MORNING AND SHIFT EAST SOME THURSDAY AFTERNOON BEFORE MOVING OUT OF THE AREA. ONCE AGAIN, H8-7 LAYER MEAN RH IS LACKING SO WILL CONTINUE SLIGHT CHANCE POPS. 850MB TEMPERATURES SUPPORT MAX TEMPERATURES REACHING THE UPPER 80S/LOWER 90S WEDNESDAY. MAX TEMPERATURES SHOULD COOL TO THE 70S THURSDAY BEHIND THE TROUGH. MIN TEMPERATURES TUESDAY NIGHT WILL BE IN THE UPPER 50S/LOWER 60S COOLING TO THE MID 50S TO LOWER 60S WEDNESDAY NIGHT. IN THE EXTENDED...(THURSDAY NIGHT THROUGH MONDAY)...THIS PART OF THE FORECAST WILL BE DRY THROUGH SATURDAY NIGHT WITH A RIDGE AND SUBSIDENCE OVER THE REGION. THE RIDGE SHIFTS EAST SUNDAY ALLOWING A TROUGH TO MOVE EAST INTO THE AREA. SLIGHT CHANCE TO CHANCE POPS ARE SUPPORTED WITH NIL POPS FOR MONDAY MAX TEMPERATURES WILL WARM UP INTO THE 80S UNDERNEATH THE INFLUENCE OF THE RIDGE AND THEN COOL TO THE MID AND UPPER 70S MONDAY BEHIND THE EXITING SHORTWAVE. MIN TEMPERATURES WILL RESIDE IN THE LOWER TO MID 50S THURSDAY AND FRIDAY NIGHTS MODERATING TO THE MID/UPPER 50S SATURDAY/SUNDAY NIGHTS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1140 PM MDT MON SEP 16 2013 IFR TO LIFR CONDITIONS ARE EXPECTED AT BOTH SITES THROUGH THE MORNING HOURS. AT KMCK...THERE IS ENOUGH OF A CHANCE TO HAVE A THUNDERSTORM AFFECT THE SITE THAT DID INCLUDE A VCTS MENTION FROM 09Z TO 12Z. BY LATE MORNING TO EARLY AFTERNOON CONDITIONS WILL IMPROVE FROM MVFR TO VFR. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...LOCKHART LONG TERM...FS AVIATION...BULLER
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
1030 PM EDT WED SEP 18 2013 .UPDATE... ISSUED AT 1030 PM EDT WED SEP 18 2013 FRESHENED UP THE SKY COVER AND HOURLY TEMPERATURES AND DEW POINTS TO ACCOUNT FOR THE LATEST TRENDS. SOME PARTIAL CLEARING WILL WORK IN FROM THE WEST...HOWEVER BELIEVE THAT LOW CLOUDS WILL FILL BACK IN DURING THE OVERNIGHT WITH HIGH MOISTURE IN THE 1000-850 MB LAYER LINGERING. LEFT THE POPS AS IS...ALTHOUGH THE LATEST HRRR HAS BACKED OFF ON THE UPTICK IN CONVECTION TOWARDS DAWN FOR THE NORTHEASTERN PORTION OF THE AREA. UPDATE ISSUED AT 807 PM EDT WED SEP 18 2013 A FEW SHOWERS WILL WIND DOWN ACROSS NORTHEASTERN KENTUCKY IN THE NEXT HOUR. THE LATEST SHORT RANGE MODELS SHOW A LULL IN THE ACTIVITY THROUGH THE OVERNIGHT...BEFORE AN UPTICK OCCURS TOWARDS DAWN IN THE NORTHEASTERN HALF OF THE AREA...AS A WEAK SHORT WAVE TROUGH MOVES SOUTHEAST ACROSS OHIO VALLEY. HAVE BUMPED UP THE POPS A BIT CONSIDERING THE DECENT MODEL AGREEMENT. ALSO ADDED SOME PATCHY FOG AND MADE THE VALLEY TEMPERATURES A BIT MORE UNIFORM WITH ALL OF THE CLOUD COVER AND STEADY DEW POINTS IN THE LOW 60S. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 307 PM EDT WED SEP 18 2013 THE MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE MAJOR UPPER AIR FEATURES...HOWEVER THERE IS QUITE A BIT OF DIFFERENCE IN HOW THEY HANDLE THE PRECIPITATION FORECASTS OVER THE NEXT 36 HOURS. A WARM FRONT HAS MOVED TO THE NORTHEAST OF THE AREA AND EASTERN KENTUCKY IS NOW IN THE WARM SECTOR WITH A SURFACE HIGH OFF THE EAST COAST AND A SURFACE RIDGE EXTENDING ACROSS EASTERN KENTUCKY. A COLD FRONT IS OVER THE HEARTLAND AND WILL BE APPROACHING THE AREA...HOWEVER WILL NOT MOVE INTO EASTERN KENTUCKY UNTIL SATURDAY. THIS ALLOWS FOR THE GULF TO BE OPENED UP AND THERE WILL BE SOME FAIRLY WARM...MOIST AND CONDITIONALLY UNSTABLE AIR OVER THE AREA. THE MODELS DIFFER AS TO WHEN WEAK LITTLE PERTURBATIONS WILL BE ABLE TO KICK OFF ANY CONVECTIVE ACTIVITY. FROM EXPERIENCE...EXPECT THAT THERE WILL BE AN AFTERNOON AND EVENING MAXIMUM OF CONVECTIVE ACTIVITY...HOWEVER THERE MAY BE SOME UNEXPECTED LITTLE POPUPS DURING THE OFF HOURS. THE MODEL BLEND HANDLED THE TEMPERATURES VERY WELL AND JUST MADE SOME MINOR TWEAKS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 307 PM EDT WED SEP 18 2013 ON FRIDAY A COLD FRONT EXTENDING FROM THE WESTERN GREAT LAKES INTO THE MID MS VALLEY WILL BE MOVING EAST AS AN UPPER LEVEL SHORT WAVE TROUGH PUSHES EAST THROUGH THE PLAINS. THE UPPER TROUGH AND SURFACE COLD FRONT WILL MOVE EAST WITH RAIN CHANCES INCREASING ACROSS THE AREA AS WE HEAD INTO THE WEEKEND. MOST RECENT RUNS OF THE VARIOUS OPERATIONAL MODELS ARE POINTING TOWARDS SLOW FRONTAL MOVEMENT WITH THE FRONT MOVING ACROSS THE AREA ON SATURDAY...AND LIKELY STALLING OUT. THE LATEST WPC GUIDANCE IS ALSO FAVORING THIS IDEA WITH THE FRONT APPROACHING THE FORECAST AREA AT 12Z SATURDAY. OF THE OPERATIONAL MODELS THE 12Z NAM IS THE OUTLIER...AS IT PUSHES THE UPPER TROUGH AND SURFACE FRONT THROUGH MUCH QUICKER...WITH THE FRONT EAST OF KY BY 15Z SATURDAY. WILL LEAN AWAY FROM THE NAM FORECAST AS ALL THE OTHER MODELS ARE MUCH SLOWER. THE 12Z GFS SHOWS THE SOUTHERN PART OF THE UPPER TROF SLOWING DOWN WITH AN UPPER LOW CLOSING OFF IN THE VICINITY OF EASTERN KY BY SUNDAY. THE 00Z ECMWF AND 12Z GEM ALSO SUPPORT THE IDEA OF SLOW MOVEMENT WITH AN UPPER LOW FORMING OVER THE UPPER SOUTH INTO THE TN VALLEY. OVERALL...MODELS AND WPC GUIDANCE POINT TOWARDS WET CONDITIONS OVER THE WEEKEND. THE LATEST BLENDED LOAD ALSO SUPPORTS THIS. EXACTLY HOW LONG THE SLOW MOVING UPPER LOW AND ASSOCIATED SURFACE LOW LINGER NEARBY AND CONTINUE TO AFFECT OUR WEATHER IS STILL UNCERTAIN. THE 00Z ECMWF POINTS TOWARDS RAIN CHANCES LINGERING INTO THE MIDDLE OF NEXT WEEK...WHILE THE 12Z GFS IS DRIER...WITH LESS OF A CHANCE OF RAIN AFTER MONDAY. WHILE THE STANDARD BLENDED LOAD RESULTED IN A CHANCE OF RAIN IN THE SOUTHEAST ON TUESDAY AND WEDNESDAY HAVE DECIDED TO FOLLOW THE CONSENSUS OF NEIGHBORING WFOS AND WILL GO WITH A DRY FORECAST ON TUESDAY AND WEDNESDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 807 PM EDT WED SEP 18 2013 EXPECT CEILINGS TO GRADUALLY LOWER TO IFR TO LIFR THROUGH DAWN...WITH WORSE CONDITIONS EXPECTED ON THE RIDGETOPS. A FEW SHOWERS WILL ALSO BE SEEN GENERALLY ALONG AND NORTHEAST OF A LINE FROM IOB TO JKL TO BLK. CEILINGS WILL GRADUALLY IMPROVE THROUGH THE MORNING HOURS...WITH MAINLY VFR EXPECTED AFTER 18Z. SOME SCATTERED CONVECTION WILL ALSO THREATEN DURING THE AFTERNOON. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...JJ LONG TERM...SBH AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS PADUCAH KY
643 PM CDT Wed Sep 18 2013 .UPDATE... ISSUED AT 642 PM CDT WED SEP 18 2013 The aviation section has been updated for the 00Z TAF issuance. && .SHORT TERM /Tonight through Friday night/... ISSUED AT 230 PM CDT WED SEP 18 2013 The showers and isolated thunderstorms that occurred this morning have all but dissipated by mid afternoon. Partial clearing will continue to spread slowly east. The trend toward low and mid level drying is indicated by RAP and nam model soundings. This drying appears to be in response to a gradual rebuilding of the 500 mb ridge that was flattened by a weak impulse this morning. Through Thursday...the mid level ridge will continue to slowly build over our region. This should continue to suppress most convection over the Lower Ohio and Mid Mississippi Valleys. Will keep slight chance pops during the peak heating hours from roughly 18z to 00z to account for isolated diurnally driven storms. A rather strong cold front will approach from the northwest on Thursday night...reaching southern Illinois and southeast Missouri on Friday. The front will continue moving southeast across western Kentucky and southwest Indiana on Friday evening. The 09z sref timing looks reasonable. A deepening upper trough will enhance lift along the frontal zone...and deep layer moisture will be high for this time of year /sref precip water values about 1.9 inches/. Looks like the first widespread significant rainfall of the month will occur. Storm total qpf should be at least one half inch...with some 1 inch amounts likely in heavier convection. Severe weather potential will depend on how much sunshine and diurnal heating takes place ahead of the front. Isolated severe convection is currently forecast by SPC /see day 3 outlook/. South to southwest low level flow will keep unseasonably warm and humid conditions in place through Friday. The nam continues to have problems with too much moisture in the model...as shown in its high pops and abundant cloudiness. The warmer gfs mos highs look better for Thursday. .LONG TERM /Saturday through Wednesday/... ISSUED AT 230 PM CDT WED SEP 18 2013 Main issue in the extended looks to be with how quickly an upper level trof will move east out of the region over the weekend. Models seem to be trending toward a less progressive solution in this respect. Both the operational GFS and ECMWF suggest showers will linger into Saturday along and south of the Ohio River, east of the H50 trof axis. Will bump up precip chances on Sat into the 40 to 50 percent range over much of the Pennyrile region of western KY. Otherwise, the most noticeable change over the weekend will be another transition to much cooler and less humid conditions. Highs both Saturday and Sunday will likely stay down in the 70s, with lows Sat night mostly in the 50 to 55 degree range. As we head into next week, it now appears as though an Omega Blocking pattern will become established along the MS River Valley. This should keep things quite dry across our region, with sunny, warm afternoons and cool nights. Temperatures will warm a touch each day, and most locations will likely be back into the middle 80s by Wednesday afternoon. Humidity levels should stay low though. && .AVIATION... ISSUED AT 642 PM CDT WED SEP 18 2013 Isolated convective activity early this evening should dissipate quickly with sunset and not pose a threat to any of the terminals. Looks like scattered mid clouds will stream across the area through the entire period, thickest in the northeast. All guidance indicates that a light south wind will persist through the night. This should prevent any significant fog formation, but will have to watch KEVV and KOWB closely due to the rainfall they received earlier today. Certainly cannot rule out MVFR visibilities at any location late tonight due to the amount of low-level moisture across the region. Will leave it out now based on the 5kt winds expected. Some guidance tries to develop scattered convection Thursday afternoon. Not sure if there will be any development, but it would likely be too sparse in coverage to warrant any mention in the TAFs at this time. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$ UPDATE...DRS SHORT TERM...MY LONG TERM...GM AVIATION...DRS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
800 PM EDT WED SEP 18 2013 LATEST UPDATE... AVIATION .SYNOPSIS... ISSUED AT 148 PM EDT WED SEP 18 2013 A WARM FRONT WILL PUSH NORTHWARD THROUGH LOWER MICHIGAN TONIGHT LEADING TO SOME SHOWERS AND THUNDERSTORMS. SOUTHWEST WINDS WILL INCREASE THURSDAY ALLOWING FOR AND UNSEASONABLY WARM DAY. MOISTURE FROM THE GULF OF MEXICO WILL STREAM INTO THE AREA THURSDAY NIGHT AND EARLY FRIDAY AHEAD OF A COLD FRONT. AS THIS FRONT PUSHES THROUGH THE REGION FRIDAY...A PERIOD OF SHOWERS AND THUNDERSTORMS CAN BE EXPECTED. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 148 PM EDT WED SEP 18 2013 THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE TIMING AND STRENGTH OF THE CONVECTION. STORMS IN NW ILLINOIS ARE SHOWN TO WEAKEN AS THEY HEAD TOWARD CHICAGO THIS AFTERNOON. HRRR SHOWS CONVECTION REDEVELOPING OVER LAKE MI LATER TONIGHT AND MOVING INTO THE HOLLAND TO MUSKEGON REGION. THIS MAKES SENSE WITH A STRENGTHENING LOW LEVEL JET ACCOMPANYING THE WARM FRONT THAT FEATURES ELEVATED INSTABILITY. NOT ALL MODELS HAVE THIS...BUT THE HRRR TENDS TO HANDLE THE CONVECTION BETTER THAN MOST. WILL DECREASE POPS INLAND TONIGHT...BUT CLOSER TO LAKE MI WILL KEEP THE LIKELY VALUES GOING. SEVERE WEATHER IS NOT FORECASTED...BUT PERHAPS A HEAVY RAIN THREAT MAY EXIST. A LULL IN THE CONVECTION IS EXPECTED THU AS NO FOCUSING MECHANISM IS SHOWN. IT WILL BE A WARM AND INCREASINGLY HUMID. IT DOES BECOME RATHER UNSTABLE...SO WILL HOLD ONTO A LOW POP FOR STORMS. I RAISED POPS FOR FRIDAY. WITH PWAT VALUES APPROACHING 2 INCHES AND A FRONT PRESSING IN ALONG WITH LIFT...IT SHOULD BE RATHER WET AT TIMES. MODELS HAVE TRENDED SOMEWHAT FASTER WITH THE FRONT...SO WE MAY BE ABLE TO START DRYING THINGS OUT FROM THE WEST BEFORE THE END OF THE DAY. WILL WAIT TO SEE IF THIS TREND PERSISTS BEFORE CHANGING FRIDAYS FORECAST. I DID LOWER POPS FOR FRIDAY NIGHT BECAUSE OF THIS. AS FOR SEVERE WEATHER...THE STRONGER DEEP LAYER SHEAR IS SHOWN TO LAG BEHIND THE COLD FRONT...SO SOMEWHAT OF A LIMITED RISK. STILL WITH BETTER INSTABILITY DEVELOPING AND INCREASING WIND FIELDS ALONG WITH A LOW LEVEL JET MOVING IN AND STRENGTHENING...A RISK STILL EXISTS. WILL NEED TO MONITOR TRENDS CLOSELY IN THE COMING DAYS. .LONG TERM...(SATURDAY THROUGH WEDNESDAY) ISSUED AT 243 PM EDT WED SEP 18 2013 AN UNEVENTFUL PERIOD IS EXCEPTED FOR THIS WEEKEND AND INTO THE FIRST HALF OF NEXT WEEK. HIGH PRESSURE OVER THE UPPER MIDWEST ON SATURDAY WILL SLOWLY MOVE OVER THE GREAT LAKES BY LATE IN THE WEEKEND. THIS HIGH WILL BE STALLED OVER THE AREA AS A STORM SYSTEM MOVES UP THE EAST COAST THROUGH THE FIRST HALF OF THE WORK WEEK. SO FAIR WEATHER SHOULD PREVAIL. LOWERED TEMPS A BIT FOR SATURDAY AND SUNDAY AS WE WILL BE UNDER A THERMAL TROUGH . BOTH DAYS SHOULD SEE HIGHS STAYING IN THE 60S. WE SHOULD SEE A WARM UP INTO THE WORK WEEK. HOWEVER LOW LEVEL FLOW WILL BE FROM THE EAST OR SOUTHEAST...SO ANY MODERATION OF TEMPS WILL BE GENTLE. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 800 PM EDT WED SEP 18 2013 THE MAIN CHALLENGE FOR THE TAFS IS WHETHER OR NOT TO INCLUDE TSTMS AND WHAT THE TIMING OF THEM MIGHT BE. LATEST HRRR AND NSSL WRF GUIDANCE SUGGESTS A FEW STORMS DEVELOPING AFTER MIDNIGHT TONIGHT ALONG THE LK MI SHORELINE THEN DRIFTING SLOWLY TO THE EAST/SOUTHEAST LATE TONIGHT INTO THURSDAY MORNING. WILL INCLUDE VCTS IN THE TAFS STARTING AROUND 05Z AT MKG WHERE THE HIGHEST POTENTIAL EXISTS AND WHERE CONFIDENCE IS MEDIUM TO HIGH. WILL HAVE THE STORMS IMPACTING/REACHING THE LAN/JXN AREAS BY 10Z... BUT CONFIDENCE IS LOWER FARTHER EAST. IF THERE ARE STORMS AROUND ON THURSDAY MORNING... A LULL SHOULD DEVELOP BETWEEN THESE STORMS /ENDING BY 18Z/... AND THE NEXT POTENTIAL ROUND ON THURSDAY EVENING... WHICH WILL PROBABLY BE AFTER 00Z FRIDAY. && .MARINE... ISSUED AT 148 PM EDT WED SEP 18 2013 WINDS ARE FORECASTED TO BE STRONGER THU INTO THU NIGHT. MAY NEED SMALL CRAFT AND BEACH HAZARDS TO COVER THIS. UNTIL THEN THE SOUTHERLY FLOW WILL KEEP WAVES UP TO AROUND 2 TO 4 FEET...ESPECIALLY OFF OF LITTLE AND BIG SABLE POINTS. && .HYDROLOGY... ISSUED AT 148 PM EDT WED SEP 18 2013 LOCALIZED HEAVY RAIN WILL BE POSSIBLE WITH THE STORMS TONIGHT AS A LOW LEVEL JET MOVES IN PWAT VALUES CLIMB TO OVER 1.5 INCHES. CORFIDI VECTORS SUGGESTS A LOCALIZED HEAVY RAIN THREAT MAY EXIST. CURRENTLY IT APPEARS THAT AREAS ALONG THE LAKESHORE STAND THE HIGHEST CHANCE FOR THE STORMS. A MORE WIDESPREAD ROUND OF STORMS IS FORECASTED FOR THU NIGHT INTO FRI. PWAT VALUES LIKELY TO CLIMB ABOVE 1.75 INCHES WITH ANOTHER LOW LEVEL JET PUSHING THROUGH. CORFIDI VECTORS ALSO SUGGEST A HEAVY RAIN THREAT. HOW MUCH RAIN FALLS WILL LIKELY DEPEND ON HOW EFFICIENT THE RAIN BECOMES AND HOW THE CONVECTION EVOLVES. SUSPECT LOCALLY MORE THAN 2 INCHES WILL FALL BY FRI NIGHT. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS...MJS SHORT TERM...MJS LONG TERM...JK AVIATION...MEADE HYDROLOGY...MJS MARINE...MJS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
422 PM EDT TUE SEP 17 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 421 PM EDT TUE SEP 17 2013 17Z WV IMAGERY AND RUC ANALYSIS INDICATED A WELL-DEFINED SHORTWAVE LIFTING NE THROUGH ERN IA. DPVA...7H FGEN AND 305K ISENTROPIC ASCENT ASSOC WITH THE SHORTWAVE HAS SUPPORTED AN AREA OF SHOWERS OVER NORTHEAST IA. VIS SATELLITE HAS SHOWN AN EXPANSION OF DIURNAL CU FROM MNM-DELTA-ALGER COUNTIES EASTWARD IN AN AREA OF HIGHER DEWPOINTS (UPPER 40 TO LOWER 50S) AIDED BY SOUTHERLY FLOW OFF LAKE MI AND BAY OF GREEN BAY. RDGG ALOFT AND AT THE SFC HAS KEPT THE REST OF THE FCST AREA GENERALLY CLOUD FREE THIS AFTERNOON. TONIGHT...MDLS SUGGEST THAT AS THE IA SHRTWV GRADUALLY LIFTS TO THE NORTHEAST...MOISTURE WILL INCREASE AND BRING SOME LIGHT WAA PCPN INTO THE AREA AS 300K-310K ISENTROPIC ASCENT SPREADS FROM SE MN AND WRN WI TOWARD UPPER MI. THE NAM/GFS ARE STILL A BIT MORE AGGRESSIVE IN BRINGING SOME LIGHT PCPN INTO THE CWA COMPARED TO THE GEM/ECMWF. GIVEN THE VERY DRY ANTECEDENT AIRMASS...THE NAM/GFS MAY BE TOO QUICK SO USED MORE OF A MODEL BLEND FOR POPS WITH ONLY A 30 PCT CHC OF LIGHT SHOWERS TOWARD 12Z NEAR THE WI BORDER WITH SLIGHT CHC ACROSS MUCH OF THE REST OF THE WEST HALF. WEDNESDAY...GIVEN PREDICTED TRACK OF ERN IA SHORTWAVE EXPECT BEST FORCING FOR SHRA TO BE MAINLY CENTRAL COUNTIES IN THE MORNING AND THEN TO SPREAD INTO THE EASTERN COUNTIES IN THE AFTERNOON. HAVE ONLY SLIGHT CHC POPS FOR SHRA WEST AWAY FROM BETTER FORCING ASSOC WITH SHORTWAVE. MODEL MLCAPES OTHER THAN NAM SHOW ONLY MARGINAL INSTABILITY OF A FEW HUNDRED J/KG AT BEST OVER THE AREA SO WILL ONLY INCLUDED SLIGHT CHC MENTION OF TS IN THE GRIDS. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 421 PM EDT TUE SEP 17 2013 LITTLE CHANGES TO THE LARGE SCALE PATTERN FOR THE LONG TERM PERIOD OVER THE LAST 24 HOURS. AREA WILL BE UNDER WEAK UPPER RIDGING TO START THE PERIOD...WHICH WILL LEAD TO BROAD WARM AIR ADVECTION AND THE POTENTIAL FOR SOME SHOWERS/THUNDERSTORMS WEDNESDAY NIGHT INTO THURSDAY AS A WARM FRONT LIFTS ACROSS THE AREA. BEST CHANCES ON WEDNESDAY NIGHT WILL BE EARLY ON WHEN THE STRONGEST WARM AIR ADVECTION MOVES THROUGH AND BEFORE THE DEEPER MOISTURE STARTS TO CUTOUT. THIS BROAD WAA WILL ALSO LEAD TO TEMPERATURES RISING TO ABOVE NORMAL VALUES FOR WEDNESDAY NIGHT AND THURSDAY...WITH LOWS IN THE UPPER 50S AND LOWER 60S AND HIGHS IN THE 70S TO LOWER 80S. FINALLY FOR WEDNESDAY NIGHT...SINCE THE MODELS CONTINUE TO SHOW THE POTENTIAL FOR LOW CLOUDS AND FOG...DID UP THE FOG TO AREAS FOR SOME LOCATIONS IN FAVORED UPSLOPE HIGHER TERRAIN. PRECIPITATION CHANCES WILL INCREASE HEADING INTO LATE THURSDAY AFTERNOON AND THURSDAY NIGHT...AS THE UPPER TROUGH PUSHES NORTHEAST THROUGH THE UPPER GREAT LAKES AND ONTARIO. AN ASSOCIATED LOW PRESSURE SYSTEM WILL MOVE THROUGH NORTHWEST ONTARIO...BUT IT WILL PUSH A COLD FRONT EAST ACROSS THE CWA THURSDAY NIGHT INTO FRIDAY MORNING. ECMWF IS STILL SHOWING THE SLOWEST FRONTAL PASSAGE...WITH THE PRECIPITATION LINGERING INTO EARLY FRIDAY AFTERNOON AS ANOTHER WAVE RIDES UP THE FRONT. THERE CONTINUES TO BE SOME MINOR TIMING DIFFERENCES IN THE COLD FRONT PASSAGE AND SHOWERS...BUT THE GENERAL IDEA IS SIMILAR WITH MOST LOCATIONS LIKELY TO SEE 0.25-0.5IN OF RAIN. AS FOR THUNDER...THERE ARE DECENT VARIATIONS IN THE INSTABILITY...WITH SOME MODELS EVEN SHOWING UP TO 3000 J/KG OF ML CAPE IF THERE IS ENOUGH CLEARING/HEATING IN THE AFTERNOON. 0-6KM AND EFFECTIVE SHEAR VALUES STILL LOOK TO BE ON THE MARGINAL SIDE (25-30KTS) ON THURSDAY AFTERNOON AND THEN INCREASE RIGHT ALONG THE FRONTAL BOUNDARY. WOULD THINK THE BEST OPPORTUNITY FOR STRONGER THUNDERSTORMS WOULD BE RIGHT ALONG THE FRONT AS IT MOVES INTO THE WESTERN CWA LATE THURSDAY AFTERNOON INTO THE EVENING. AT THIS POINT...THINK BRIEF HEAVY RAIN AND MARGINALLY SEVERE HAIL WOULD BE THE BIGGEST THREATS IF THE UPDRAFTS CAN BE SUSTAINED. DRIER AND COOLER AIR WILL MOVE IN RIGHT BEHIND THE FRONT AND SHOULD LEAD TO A PERIOD OF DRY WEATHER AND EVEN SOME CLEARING FOR A FEW HOURS. BUT MUCH COLDER AIR...WILL START TO SURGE IN WITH MORE LOW LEVEL MOISTURE LATER FRIDAY AFTERNOON AND CONTINUE INTO THE FIRST PART OF SATURDAY. WITH THE FLOW BEING MORE WEST-NORTHWEST...EXPECT THE MOST CLOUDS TO BE OVER THE NORTH HALF OF THE CWA AND WITH THE COLDER AIR THERE...EVEN SOME LAKE ENHANCED CLOUDS (DELTA-T VALUES BETWEEN 10-14) IN THOSE WIND FAVORED AREAS. WITH THE LATEST TRENDS OF CLOUD DEPTHS BEING 3-4KFT...SHOULD BE ENOUGH FOR ISOLATED/SCATTERED SHOWERS AND MAY NEED TO ADJUST POPS A LITTLE HIGHER OVER THE COMING SHIFTS. THE UPPER TROUGH WILL LIFT NORTHEAST ON SATURDAY NIGHT AND ALLOW UPPER RIDGING AND HIGH PRESSURE TO BUILD INTO THE AREA FOR SUNDAY. THUS...EXPECT A DRY SECOND HALF OF THE WEEKEND...ALTHOUGH TEMPERATURES WON/T WARM UP TOO SIGNIFICANTLY (WITH HIGHS AROUND 60). ALSO...SATURDAY NIGHT COULD SEE SOME FROST OVER THE INTERIOR WEST WHERE SKIES BEGIN TO CLEAR AND WINDS LET UP DUE TO THE APPROACHING HIGH. THIS HIGH WILL QUICKLY SHIFT EAST-NORTHEAST INTO QUEBEC ON MONDAY...AS THE AREA IS UNDER THE UPPER RIDGE AXIS. STILL EXPECT MONDAY TO BE DRY AND MUCH WARMER (HIGHS IN THE MID-UPPER 60S)...BUT THE NEXT UPPER TROUGH IS LURKING TO THE WEST. THIS UPPER TROUGH LOOKS TO GIVE A GLANCING BLOW TO THE CWA ON MONDAY NIGHT INTO TUESDAY AND WILL HIGHLIGHT THE BEST POPS OVER THE NORTHWESTERN HALF OF THE CWA. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 201 PM EDT TUE SEP 17 2013 WITH DRY HIGH PRES DOMINATING...VFR CONDITIONS WILL BE THE RULE FOR ALL TAF SITES THROUGH THIS EVENING. A STRENGTHENING SOUTHERLY PRES GRAD JUST ABV DEVELOPING RADIATION INVERSION WILL RESULT IN LLWS TONIGHT AT TAF SITES. LATE TONIGHT...INCREASING LOW LEVEL MOISTURE MOVING NORTHWARD FROM WI AHEAD OF AN ADVANCING SYSTEM OVER THE CENTRAL PLAINS IS EXPECTED TO BRING MVFR CIGS INTO THE TAF SITES LATE TONIGHT INTO MIDDAY WEDNESDAY. KSAW WILL HAVE THE BEST CHC OF PREVAILING SHRA CLOSER TO THE BEST FORCING FROM THE SYSTEM WHILE KIWD AND KCMX SHOULD ONLY SEE VCSH && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 421 PM EDT TUE SEP 17 2013 BETWEEN HIGH TO THE EAST AND LOW PRES OVER THE PLAINS...SRLY WINDS WILL REMAIN UP TO 20 KNOTS INTO WED. WINDS SHOULD THEN REMAIN BELOW 20 KNOTS UNTIL LATE THU NIGHT AND FRI WHEN A COLD FRONT MOVES THROUGH THE REGION AND BRINGS W TO NW WINDS UP TO 30 KNOTS FRI INTO SAT. WINDS WILL DECREASE BLO 20 KT BY SUNDAY AS HIGH PRESSURE BUILDS IN FM THE WEST. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...VOSS LONG TERM...SRF AVIATION...VOSS MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
215 PM EDT TUE SEP 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 508 AM EDT TUE SEP 17 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE FROM IL/WI INTO NW ONTARIO. AT THE SFC...A RIDGE WAS LOCATED OVER THE ERN GREAT LAKES RESULTING IN SRLY THROUGH THE UPPER MS VALLEY INTO THE WRN CWA. THE COMBINATION OF WAA AND A WEAK UPSTREAM SHORTWAVE TROUGH OVER IA SUPPORTED AN AREA OF LIGHT SHOWERS FROM ERN NEB INTO NW IA. OTHERWISE...IR LOOP INDICATED CLEAR SKIES OVER THE NRN GREAT LAKES. TODAY...HIGH PRES AND THE LINGERING DRY AIRMASS WILL CONTINUE TO DOMINATE THE WEATHER WITH MOSTLY SUNNY SKIES OVER UPPER MI. MIXING TO AROUND 900-875 MB (AROUND 11C) WILL RESULT IN MAX READINGS IN THE MID TO UPPER 60S. TONIGHT...MDLS SUGGEST THAT AS THE IA SHRTWV GRADUALLY LIFTS TO THE NORTHEAST...MOISTURE WILL INCREASE AND SOME LIGHT WAA PCPN WITH AREA OF 300K-310K ISENTROPIC LIFT WILL SPREAD FROM SE MN AND WRN WI TOWARD UPPER MI. THE NAM/GFS WERE A BIT MORE AGGRESSIVE IN BRINGING SOME LIGHT PCPN INTO THE CWA COMPARED TO THE GEM/ECMWF. GIVEN THE VERY DRY ANTECEDENT AIRMASS...THE FCST LEANS MORE TOWARD THE SLOWER ONSET OF PCPN WITH ONLY A SLIGHT CHANCE OF LIGHT SHOWERS TOWARD 12Z NEAR THE WI BORDER. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 447 AM EDT TUE SEP 17 2013 WED THROUGH MOST OF THU...A LOW PRESSURE SYSTEM CURRENTLY OFF THE PACIFIC NW CONUS WILL DEEPEN WHILE MOVING FROM MT AT 12Z WED TO THE CENTRAL SASKATCHEWAN/ONTARIO BORDER BY 00Z FRI. WILL DISCUSS PRECIP ALONG THE COLD FRONT THAT MOVES IN LATE THU MOMENTARILY...BUT BEFORE THAT MOVES IN EXPECT JUST SOME MINOR PRECIP. BEST CHANCE FOR PRECIP LOOKS TO BE WITH BROAD WAA AHEAD OF THE SYSTEM...SO SOME LIGHT PRECIP IS DIFFICULT TO FORECAST. HOWEVER...AGREE WITH PREVIOUS SHIFT THAT SLIGHT CHANCE TO LOW CHANCE POPS SEEM WARRANTED PRIOR TO COLD FROPA. HIGHS WED LOOK TO BE AROUND 70 WITH 850MB TEMPS OF 10-14C. THU TEMPS LOOKS MORE CONDITIONAL AS LOW CLOUDS MAY INHIBIT MIXING OF 14-19C 850MB TEMPS...BUT COULD SEE HIGHS IN THE MID 70S IF ENOUGH CLEARING OCCURS. NOW FOR THE PROMISED DISCUSSION OF PRECIP ALONG THE COLD FRONT. THE LOW WILL CONTINUE DEEPENING AS IT MOVES TO HUDSON BAY BY 00Z SAT...THEN REMAINS NEARLY STATIONARY WHILE OCCLUDING THROUGH THE REST OF SAT. WHILE DISCUSSING THE TRACK/TIMING OF THE SYSTEM...LET IT BE SAID THAT MODELS ARE DOING MUCH BETTER THAN 24 HOURS AGO...BOTH WITH RUN TO RUN CONTINUITY AND WITH MODEL TO MODEL AGREEMENT. STILL THINK THERE WILL BE SHIFTS IN THE TRACK/TIMING BY THE MODELS OVER THE NEXT FEW RUNS...BUT SHOULD AT LEAST BE GETTING A BETTER IDEA OF WHAT THE SYSTEM WILL DO. THE COLD FRONT TIMING IS ALSO SIMILAR BETWEEN MODEL RUNS...AT LEAST RELATIVELY SO FOR THIS TYPE OF SYSTEM...WITH THE FRONT MOVING INTO THE FAR WRN CWA AROUND 00Z FRI...THEN TO THE CENTRAL CWA AROUND 12Z FRI AND TO THE ERN CWA BY 18Z FRI. EXPECT A LINE OF SHOWERS AND THUNDERSTORMS TO MOVE ACROSS THE CWA MAINLY THU NIGHT...AND AGREE WITH PREVIOUS SHIFT THAT LIKELY POPS ARE JUSTIFIED. DRY SLOT MOVES IN BEHIND THE FRONT...WHICH SHOULD BRING AN END TO SYNOPTIC PRECIP AS THE MID/UPPER LEVELS DRY OUT. HOWEVER...WRAP AROUND MOISTURE WILL STILL BE PRESENT IN THE LOW LEVELS AS THE UPPER TROUGH MOVES OVERHEAD FRI INTO FRI NIGHT WITH 850MB TEMPS AS LOW AS 1C THROUGH 00Z FRI AND AS LOW AS -2C FRI NIGHT. WLY LOW LEVEL WINDS MEANS THE W WIND LAKE EFFECT/UPSLOPE BELTS WILL SEE THE BEST CHANCES FOR RAIN BEHIND THE FRONT FRI AND FRI NIGHT. MODELS DO START TO VARY MORE WITH HOW LONG TO LINGER THE UPPER TROUGH OVER THE AREA SAT AND HOW QUICK TO BRING IN AN UPPER RIDGE FROM THE W. THE GFS IS SLOWER WITH THE TROUGH AND HAS 850MB TEMPS AROUND -2C AT 00Z SUN WHILE THE ECMWF HAS 850MB TEMPS OF 2-8C AT THE SAME TIME. THEREFORE...HAVE LITTLE CONFIDENCE IN TEMPS FOR SAT. WITH SUCH A SPREAD IN LOW LEVEL TEMPS...THERE IS ALSO A SPREAD IN POSSIBILITIES FOR LAKE EFFECT RAIN...SO WILL CONTINUE TO HAVE SLIGHT CHANCE IN THE FORECAST. SUN SHOULD SEE A WARM UP AS THE UPPER RIDGE MOVES OVERHEAD...BUT STILL NOT VERY CONFIDENT ON EXACT TEMPS FOR THE DAY GIVEN CONTINUED MODEL SPREAD...BUT AT LEAST SHOULD BE WARMER AND DRIER THAN SAT. MON SHOULD AGAIN SEE WARMING TEMPS AS SLY FLOW INCREASES AHEAD OF THE NEXT LOW PRESSURE SYSTEM DEVELOPING OVER THE PLAINS. . && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 201 PM EDT TUE SEP 17 2013 WITH DRY HIGH PRES DOMINATING...VFR CONDITIONS WILL BE THE RULE FOR ALL TAF SITES THROUGH THIS EVENING. A STRENGTHENING SOUTHERLY PRES GRAD JUST ABV DEVELOPING RADIATION INVERSION WILL RESULT IN LLWS TONIGHT AT TAF SITES. LATE TONIGHT...INCREASING LOW LEVEL MOISTURE MOVING NORTHWARD FROM WI AHEAD OF AN ADVANCING SYSTEM OVER THE CENTRAL PLAINS IS EXPECTED TO BRING MVFR CIGS INTO THE TAF SITES LATE TONIGHT INTO MIDDAY WEDNESDAY. KSAW WILL HAVE THE BEST CHC OF PREVAILING SHRA CLOSER TO THE BEST FORCING FROM THE SYSTEM WHILE KIWD AND KCMX SHOULD ONLY SEE VCSH && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 508 AM EDT TUE SEP 17 2013 AS THE HIGH SHIFTS TO THE EAST...SRLY WINDS UP TO 20 KNOTS ARE EXPECTED FROM TODAY INTO WED. WINDS SHOULD THEN REMAIN BELOW 20 KNOTS UNTIL FRI WHEN A COLD FRONT MOVES THROUGH THE REGION AND BRINGS W TO NW WINDS UP TO 30 KNOTS FRI INTO SAT. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...TITUS AVIATION...VOSS MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
750 AM EDT TUE SEP 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 508 AM EDT TUE SEP 17 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE FROM IL/WI INTO NW ONTARIO. AT THE SFC...A RIDGE WAS LOCATED OVER THE ERN GREAT LAKES RESULTING IN SRLY THROUGH THE UPPER MS VALLEY INTO THE WRN CWA. THE COMBINATION OF WAA AND A WEAK UPSTREAM SHORTWAVE TROUGH OVER IA SUPPORTED AN AREA OF LIGHT SHOWERS FROM ERN NEB INTO NW IA. OTHERWISE...IR LOOP INDICATED CLEAR SKIES OVER THE NRN GREAT LAKES. TODAY...HIGH PRES AND THE LINGERING DRY AIRMASS WILL CONTINUE TO DOMINATE THE WEATHER WITH MOSTLY SUNNY SKIES OVER UPPER MI. MIXING TO AROUND 900-875 MB (AROUND 11C) WILL RESULT IN MAX READINGS IN THE MID TO UPPER 60S. TONIGHT...MDLS SUGGEST THAT AS THE IA SHRTWV GRADUALLY LIFTS TO THE NORTHEAST...MOISTURE WILL INCREASE AND SOME LIGHT WAA PCPN WITH AREA OF 300K-310K ISENTROPIC LIFT WILL SPREAD FROM SE MN AND WRN WI TOWARD UPPER MI. THE NAM/GFS WERE A BIT MORE AGGRESSIVE IN BRINGING SOME LIGHT PCPN INTO THE CWA COMPARED TO THE GEM/ECMWF. GIVEN THE VERY DRY ANTECEDENT AIRMASS...THE FCST LEANS MORE TOWARD THE SLOWER ONSET OF PCPN WITH ONLY A SLIGHT CHANCE OF LIGHT SHOWERS TOWARD 12Z NEAR THE WI BORDER. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 447 AM EDT TUE SEP 17 2013 WED THROUGH MOST OF THU...A LOW PRESSURE SYSTEM CURRENTLY OFF THE PACIFIC NW CONUS WILL DEEPEN WHILE MOVING FROM MT AT 12Z WED TO THE CENTRAL SASKATCHEWAN/ONTARIO BORDER BY 00Z FRI. WILL DISCUSS PRECIP ALONG THE COLD FRONT THAT MOVES IN LATE THU MOMENTARILY...BUT BEFORE THAT MOVES IN EXPECT JUST SOME MINOR PRECIP. BEST CHANCE FOR PRECIP LOOKS TO BE WITH BROAD WAA AHEAD OF THE SYSTEM...SO SOME LIGHT PRECIP IS DIFFICULT TO FORECAST. HOWEVER...AGREE WITH PREVIOUS SHIFT THAT SLIGHT CHANCE TO LOW CHANCE POPS SEEM WARRANTED PRIOR TO COLD FROPA. HIGHS WED LOOK TO BE AROUND 70 WITH 850MB TEMPS OF 10-14C. THU TEMPS LOOKS MORE CONDITIONAL AS LOW CLOUDS MAY INHIBIT MIXING OF 14-19C 850MB TEMPS...BUT COULD SEE HIGHS IN THE MID 70S IF ENOUGH CLEARING OCCURS. NOW FOR THE PROMISED DISCUSSION OF PRECIP ALONG THE COLD FRONT. THE LOW WILL CONTINUE DEEPENING AS IT MOVES TO HUDSON BAY BY 00Z SAT...THEN REMAINS NEARLY STATIONARY WHILE OCCLUDING THROUGH THE REST OF SAT. WHILE DISCUSSING THE TRACK/TIMING OF THE SYSTEM...LET IT BE SAID THAT MODELS ARE DOING MUCH BETTER THAN 24 HOURS AGO...BOTH WITH RUN TO RUN CONTINUITY AND WITH MODEL TO MODEL AGREEMENT. STILL THINK THERE WILL BE SHIFTS IN THE TRACK/TIMING BY THE MODELS OVER THE NEXT FEW RUNS...BUT SHOULD AT LEAST BE GETTING A BETTER IDEA OF WHAT THE SYSTEM WILL DO. THE COLD FRONT TIMING IS ALSO SIMILAR BETWEEN MODEL RUNS...AT LEAST RELATIVELY SO FOR THIS TYPE OF SYSTEM...WITH THE FRONT MOVING INTO THE FAR WRN CWA AROUND 00Z FRI...THEN TO THE CENTRAL CWA AROUND 12Z FRI AND TO THE ERN CWA BY 18Z FRI. EXPECT A LINE OF SHOWERS AND THUNDERSTORMS TO MOVE ACROSS THE CWA MAINLY THU NIGHT...AND AGREE WITH PREVIOUS SHIFT THAT LIKELY POPS ARE JUSTIFIED. DRY SLOT MOVES IN BEHIND THE FRONT...WHICH SHOULD BRING AN END TO SYNOPTIC PRECIP AS THE MID/UPPER LEVELS DRY OUT. HOWEVER...WRAP AROUND MOISTURE WILL STILL BE PRESENT IN THE LOW LEVELS AS THE UPPER TROUGH MOVES OVERHEAD FRI INTO FRI NIGHT WITH 850MB TEMPS AS LOW AS 1C THROUGH 00Z FRI AND AS LOW AS -2C FRI NIGHT. WLY LOW LEVEL WINDS MEANS THE W WIND LAKE EFFECT/UPSLOPE BELTS WILL SEE THE BEST CHANCES FOR RAIN BEHIND THE FRONT FRI AND FRI NIGHT. MODELS DO START TO VARY MORE WITH HOW LONG TO LINGER THE UPPER TROUGH OVER THE AREA SAT AND HOW QUICK TO BRING IN AN UPPER RIDGE FROM THE W. THE GFS IS SLOWER WITH THE TROUGH AND HAS 850MB TEMPS AROUND -2C AT 00Z SUN WHILE THE ECMWF HAS 850MB TEMPS OF 2-8C AT THE SAME TIME. THEREFORE...HAVE LITTLE CONFIDENCE IN TEMPS FOR SAT. WITH SUCH A SPREAD IN LOW LEVEL TEMPS...THERE IS ALSO A SPREAD IN POSSIBILITIES FOR LAKE EFFECT RAIN...SO WILL CONTINUE TO HAVE SLIGHT CHANCE IN THE FORECAST. SUN SHOULD SEE A WARM UP AS THE UPPER RIDGE MOVES OVERHEAD...BUT STILL NOT VERY CONFIDENT ON EXACT TEMPS FOR THE DAY GIVEN CONTINUED MODEL SPREAD...BUT AT LEAST SHOULD BE WARMER AND DRIER THAN SAT. MON SHOULD AGAIN SEE WARMING TEMPS AS SLY FLOW INCREASES AHEAD OF THE NEXT LOW PRESSURE SYSTEM DEVELOPING OVER THE PLAINS. . && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 750 AM EDT TUE SEP 17 2013 WITH DRY HIGH PRES DOMINATING...VFR CONDITIONS WILL BE THE RULE FOR MOST OF THE FCST PERIOD AT ALL 3 TAF SITES. AS THE HIGH DRIFTS FARTHER E AND A STRONGER PRES GRADIENT TAKES SHAPE OVER THE NRN GREAT LAKES...EXPECT A GUSTY S WIND TO DEVELOP BY THIS AFTERNOON IN THE PRESENCE OF DAYTIME HEATING/MIXING. LLWS WILL RESULT TONIGHT WITH NOCTURNAL COOLING CAUSING A RADIATION INVERSION AND DECOUPLING OF A LIGHTER SFC FLOW FM THE STRONGER WINDS ABOVE THE INVERSION. LATE TONIGHT...INCREASING LOW LEVEL MOISTURE MOVING NORTHWARD FROM WI IS EXPECTED TO BRING MVFR CIGS INTO IWD/SAW TOWARD THE END OF THE FCST PERIOD. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 508 AM EDT TUE SEP 17 2013 AS THE HIGH SHIFTS TO THE EAST...SRLY WINDS UP TO 20 KNOTS ARE EXPECTED FROM TODAY INTO WED. WINDS SHOULD THEN REMAIN BELOW 20 KNOTS UNTIL FRI WHEN A COLD FRONT MOVES THROUGH THE REGION AND BRINGS W TO NW WINDS UP TO 30 KNOTS FRI INTO SAT. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... FROST ADVISORY UNTIL 9 AM EDT /8 AM CDT/ THIS MORNING FOR MIZ002- 004>007-009>014-084-085. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...TITUS AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
509 AM EDT TUE SEP 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 508 AM EDT TUE SEP 17 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE FROM IL/WI INTO NW ONTARIO. AT THE SFC...A RIDGE WAS LOCATED OVER THE ERN GREAT LAKES RESULTING IN SRLY THROUGH THE UPPER MS VALLEY INTO THE WRN CWA. THE COMBINATION OF WAA AND A WEAK UPSTREAM SHORTWAVE TROUGH OVER IA SUPPORTED AN AREA OF LIGHT SHOWERS FROM ERN NEB INTO NW IA. OTHERWISE...IR LOOP INDICATED CLEAR SKIES OVER THE NRN GREAT LAKES. TODAY...HIGH PRES AND THE LINGERING DRY AIRMASS WILL CONTINUE TO DOMINATE THE WEATHER WITH MOSTLY SUNNY SKIES OVER UPPER MI. MIXING TO AROUND 900-875 MB (AROUND 11C) WILL RESULT IN MAX READINGS IN THE MID TO UPPER 60S. TONIGHT...MDLS SUGGEST THAT AS THE IA SHRTWV GRADUALLY LIFTS TO THE NORTHEAST...MOISTURE WILL INCREASE AND SOME LIGHT WAA PCPN WITH AREA OF 300K-310K ISENTROPIC LIFT WILL SPREAD FROM SE MN AND WRN WI TOWARD UPPER MI. THE NAM/GFS WERE A BIT MORE AGGRESSIVE IN BRINGING SOME LIGHT PCPN INTO THE CWA COMPARED TO THE GEM/ECMWF. GIVEN THE VERY DRY ANTECEDENT AIRMASS...THE FCST LEANS MORE TOWARD THE SLOWER ONSET OF PCPN WITH ONLY A SLIGHT CHANCE OF LIGHT SHOWERS TOWARD 12Z NEAR THE WI BORDER. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 447 AM EDT TUE SEP 17 2013 WED THROUGH MOST OF THU...A LOW PRESSURE SYSTEM CURRENTLY OFF THE PACIFIC NW CONUS WILL DEEPEN WHILE MOVING FROM MT AT 12Z WED TO THE CENTRAL SASKATCHEWAN/ONTARIO BORDER BY 00Z FRI. WILL DISCUSS PRECIP ALONG THE COLD FRONT THAT MOVES IN LATE THU MOMENTARILY...BUT BEFORE THAT MOVES IN EXPECT JUST SOME MINOR PRECIP. BEST CHANCE FOR PRECIP LOOKS TO BE WITH BROAD WAA AHEAD OF THE SYSTEM...SO SOME LIGHT PRECIP IS DIFFICULT TO FORECAST. HOWEVER...AGREE WITH PREVIOUS SHIFT THAT SLIGHT CHANCE TO LOW CHANCE POPS SEEM WARRANTED PRIOR TO COLD FROPA. HIGHS WED LOOK TO BE AROUND 70 WITH 850MB TEMPS OF 10-14C. THU TEMPS LOOKS MORE CONDITIONAL AS LOW CLOUDS MAY INHIBIT MIXING OF 14-19C 850MB TEMPS...BUT COULD SEE HIGHS IN THE MID 70S IF ENOUGH CLEARING OCCURS. NOW FOR THE PROMISED DISCUSSION OF PRECIP ALONG THE COLD FRONT. THE LOW WILL CONTINUE DEEPENING AS IT MOVES TO HUDSON BAY BY 00Z SAT...THEN REMAINS NEARLY STATIONARY WHILE OCCLUDING THROUGH THE REST OF SAT. WHILE DISCUSSING THE TRACK/TIMING OF THE SYSTEM...LET IT BE SAID THAT MODELS ARE DOING MUCH BETTER THAN 24 HOURS AGO...BOTH WITH RUN TO RUN CONTINUITY AND WITH MODEL TO MODEL AGREEMENT. STILL THINK THERE WILL BE SHIFTS IN THE TRACK/TIMING BY THE MODELS OVER THE NEXT FEW RUNS...BUT SHOULD AT LEAST BE GETTING A BETTER IDEA OF WHAT THE SYSTEM WILL DO. THE COLD FRONT TIMING IS ALSO SIMILAR BETWEEN MODEL RUNS...AT LEAST RELATIVELY SO FOR THIS TYPE OF SYSTEM...WITH THE FRONT MOVING INTO THE FAR WRN CWA AROUND 00Z FRI...THEN TO THE CENTRAL CWA AROUND 12Z FRI AND TO THE ERN CWA BY 18Z FRI. EXPECT A LINE OF SHOWERS AND THUNDERSTORMS TO MOVE ACROSS THE CWA MAINLY THU NIGHT...AND AGREE WITH PREVIOUS SHIFT THAT LIKELY POPS ARE JUSTIFIED. DRY SLOT MOVES IN BEHIND THE FRONT...WHICH SHOULD BRING AN END TO SYNOPTIC PRECIP AS THE MID/UPPER LEVELS DRY OUT. HOWEVER...WRAP AROUND MOISTURE WILL STILL BE PRESENT IN THE LOW LEVELS AS THE UPPER TROUGH MOVES OVERHEAD FRI INTO FRI NIGHT WITH 850MB TEMPS AS LOW AS 1C THROUGH 00Z FRI AND AS LOW AS -2C FRI NIGHT. WLY LOW LEVEL WINDS MEANS THE W WIND LAKE EFFECT/UPSLOPE BELTS WILL SEE THE BEST CHANCES FOR RAIN BEHIND THE FRONT FRI AND FRI NIGHT. MODELS DO START TO VARY MORE WITH HOW LONG TO LINGER THE UPPER TROUGH OVER THE AREA SAT AND HOW QUICK TO BRING IN AN UPPER RIDGE FROM THE W. THE GFS IS SLOWER WITH THE TROUGH AND HAS 850MB TEMPS AROUND -2C AT 00Z SUN WHILE THE ECMWF HAS 850MB TEMPS OF 2-8C AT THE SAME TIME. THEREFORE...HAVE LITTLE CONFIDENCE IN TEMPS FOR SAT. WITH SUCH A SPREAD IN LOW LEVEL TEMPS...THERE IS ALSO A SPREAD IN POSSIBILITIES FOR LAKE EFFECT RAIN...SO WILL CONTINUE TO HAVE SLIGHT CHANCE IN THE FORECAST. SUN SHOULD SEE A WARM UP AS THE UPPER RIDGE MOVES OVERHEAD...BUT STILL NOT VERY CONFIDENT ON EXACT TEMPS FOR THE DAY GIVEN CONTINUED MODEL SPREAD...BUT AT LEAST SHOULD BE WARMER AND DRIER THAN SAT. MON SHOULD AGAIN SEE WARMING TEMPS AS SLY FLOW INCREASES AHEAD OF THE NEXT LOW PRESSURE SYSTEM DEVELOPING OVER THE PLAINS. . && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 129 AM EDT TUE SEP 17 2013 WITH DRY HI PRES DOMINATING...VFR CONDITIONS WL BE THE RULE THIS FCST PERIOD AT ALL 3 TAF SITES. AS THE HI DRIFTS FARTHER E AND A STRONGER PRES GRADIENT TAKES SHAPE OVER THE UPR LKS...EXPECT A GUSTY S WIND TO DVLP BY THIS AFTN IN THE PRESENCE OF DAYTIME HEATING/ MIXING. LLWS WL RESULT TNGT WITH NOCTURNAL COOLING CAUSING A RADIATION INVRN AND DECOUPLING OF A LIGHTER SFC FLOW FM THE STRONGER WINDS ABV THE INVRN. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 508 AM EDT TUE SEP 17 2013 AS THE HIGH SHIFTS TO THE EAST...SRLY WINDS UP TO 20 KNOTS ARE EXPECTED FROM TODAY INTO WED. WINDS SHOULD THEN REMAIN BELOW 20 KNOTS UNTIL FRI WHEN A COLD FRONT MOVES THROUGH THE REGION AND BRINGS W TO NW WINDS UP TO 30 KNOTS FRI INTO SAT. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... FROST ADVISORY UNTIL 9 AM EDT /8 AM CDT/ THIS MORNING FOR MIZ002- 004>007-009>014-084-085. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...TITUS AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
705 PM CDT WED SEP 18 2013 .UPDATE... 00Z AVIATION DISCUSSION ADDED BELOW. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 246 PM CDT WED SEP 18 2013 TODAY THRU TONIGHT...FAIRLY ACTIVE 24 HOURS AS A FRONTAL SYSTEM MOVES ACROSS THE AREA. A WMFNT IS MAKING DECENT PROGRESS INTO SWRN MN AS THAT PORTION OF THE STATE HAS CLEARED OUT...ALLOWING TEMPERATURES TO SOAR INTO THE MID 80S. HOWEVER...WHERE THE LOW STRATUS HAS HELD ON RATHER STRONG...WHICH INCLUDES MUCH OF CENTRAL-EASTERN MN INTO WRN WI...TEMPS ARE STILL IN THE MID 60S TO MID 70S. THE WRN FRINGES OF THE CLOUD SHIELD WILL CONTINUE TO ERODE TO THE NE...BUT AS THE WMFNT MAKES FURTHER PROGRESS...THE MOIST AND WARM LLVL FLOW WILL AGAIN TAKE HOLD UNDER THE INVERSION...BRINGING LOW CLOUDS AGAIN TO THE AREA. THE HIGHER DEWPOINTS AND WARM AIR WILL MAKE FOR A RELATIVELY MUGGY NIGHT WITH LESS WIND TO MIX THE BLYR SO PATCHY FOG MAY AGAIN BE AN ISSUE. THAT SAID...SREF/RAP/NAM HINT AGAINST THAT SUGGESTION AS DO CROSSOVER TEMPS SO HAVE NOT MADE MENTION OF FOG ATTM. NOT FAR BEHIND THE WMFNT WILL BE ITS ASSOCIATED CDFNT ...WITH THE MAIN SFC LOW PRES CENTER ROTATING NEWD FROM THE CENTRAL DAKOTAS TWD NW MN AND SRN ONTARIO. THE SFC LOW WILL BE PICKED UP BY A DIGGING LONGWAVE H5 TROF OVER THE NRN PLAINS...SO AS THIS TROF DIGS...THE ADDED JETTING WILL GIVE FURTHER IMPETUS TO SHWR/TSTM DEVELOPMENT IN ADVANCE OF THE CDFNT. PRECIP DEVELOPMENT WILL COMMENCE IN EARNEST OVERNIGHT FROM S TO N...AND LOOKS TO ENVELOP MUCH OF THE CWFA IN SCATTERED COVERAGE CLOSE TO DAYBREAK. THE PRECIP WILL THEN SPREAD EWD THRU MUCH OF THE DAY TMRW...COMING TO AN END FROM W TO E OVER MN DURG THE DAY TMRW. THERE IS POTENTIAL FOR SOME DECENT PRECIP TOTALS AS PWATS REACH THE 1.75 INCH AREA... BUT EVEN WITH SUCH MOIST AIR...INSTABILITY WILL BE STRONGLY LIMITED BY THE DEEP WARM AIRMASS LEADING EXTENSIVE PERSISTENT CLOUD COVER WHICH WILL PREVENT OPTIMAL SFC HEATING. MODELS INDICATE MLCAPES IN THE 1500-2000 J/KG RANGE...POSSIBLY LEADING TO ELEVATED TSTMS...BUT SO LONG AS THE LOW CLOUDS REMAIN IN PLACE...GETTING DEEP CONVECTION WILL BE DIFFICULT. WILL MAINTAIN MENTION OF TSTMS FOR TMRW BUT CONFIDENCE IS NOT GREAT ON PLACEMENT OR TIMING. REGARDING THE WARM TEMPS...THE SLY FLOW THRU TNGT AND THE CLOUD BLANKET WILL ONLY ALLOW LOWS TNGT TO DROP TO THE MID 60S TO LWR 70S. AHEAD OF THE CDFNT TMRW... HIGHS WILL REACH THE MID 70S TO ARND 80 IN CENTRAL-SRN MN AND THE LOW-MID 80S IN WRN WI. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 246 PM CDT WED SEP 18 2013 THE BASE OF THE TROUGH ASSOCIATED WITH THE AFOREMENTIONED SYSTEM IN THE SHORT TERM DISCUSSION WILL TRANSVERSE MN BETWEEN 06-15Z THURSDAY AND MOVE INTO WI BEFORE 18Z ON THURSDAY. THIS SYSTEM HAS TRENDED 3-6 HOURS FASTER OFF THE GFS AND ECMWF OVER THE PAST FEW RUNS...WHILE THE NAM HAS REMAINED VERY STEADY. AS A RESULT...WE TRENDED THE PRECIP OUT OF THE FORECAST AREA A TAD FASTER THAN THE MIDNIGHT FORECAST...VERY LITTLE CHANGE OVERALL THOUGH. MUCH DRIER/COOLER POST FRONTAL AIR MOVES IN ON FRIDAY WITH HIGHS IN THE 60S. FRIDAY MORNING SHOULD RESEMBLE A TYPICALLY CRISP AND BREEZY FALL MORNING. NORTHWEST FLOW LINGERS ON SATURDAY WITH TEMPS REMAINING COOL. RETURN FLOW SETS IN TOWARD THE END OF THE WEEKEND...BUT AT LEAST AT THIS POINT...IT LOOKS AS IF THE THERMAL RIDGE REMAINS WEST OF THE FORECAST AREA THROUGH AT LEAST MID WEEK. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 705 PM CDT WED SEP 18 2013 WARM FRONT/CLEARING CONTINUING TO LIFT NE AT ABOUT 25 KTS AND EXPECT ALL AIRPORTS TO BE VFR BY 00Z. ALL MODELS SHOW THESE LOW CLOUDS STAYING NORTH OF THE FIELD THE REST OF THE NIGHT...SO TRENDED 00Z TAFS TOWARD A MORE OPTIMISTIC DIRECTION. THE REALLY HARD CALL STILL THIS PERIOD IS WHAT WILL HAPPEN WITH CONVECTION. THERE ARE TWO AREAS TO WATCH...THE STORMS ASSOCIATED MORE WITH THE UPPER WAVE IN NW SODAK...AND THE STRENGTHENING LLJ ACROSS IOWA. THE LINE OF STORMS MORE IN THE ERN DAKOTAS IS SFC BASED...BUT WILL REMAIN NEAR THE LOW/COLD FRONT THROUGH THE EVENING AND WILL NOT COME TOWARD THE MPX AREA UNTIL THE UPPER WAVE CATCHES UP...WHICH IS AFTER 03Z. FOLLOWED THE IDEA OF THE HRRR FOR TIMING POTENTIAL SHRA INTO AXN/STC OVERNIGHT. AS FOR THE LLJ...THE HRRR HAS BEEN VERY AGGRESSIVE WITH DEVELOPING ACTIVITY ON THE NOSE IT ACROSS SE MN INTO WRN WI THIS EVENING...BUT TO THIS POINT...IT HAS BEEN NOTHING MORE THAN A STABLE CU-FIELD ACROSS IOWA. WENT WITH VCSH FOR MSP/RNH/EAU AFTER 9Z TO ACCOUNT FOR THIS. WITH THE HRRR BEING ABOUT THE ONLY HI-RES GUIDANCE SHOWING THIS SCENARIO...CONFIDENCE NOT HIGH ENOUGH TO GO WITH ANYTHING MORE. AS FOR THE COLD FRONT... BASED ON THE HRRR/18Z NAM...IT LOOKS TO BE COMING THROUGH A COUPLE OF HOURS EARLIER THAN WHAT 12Z GUIDANCE WAS SHOWING...SO MOVED UP THUNDER MENTION ACCORDINGLY AT ERN TERMINALS. AS FOR ANY MVFR CIGS...BEST CHANCE FOR SEEING THOSE RETURN TONIGHT BASED ON THE RAP WILL BE IN WRN WI. KMSP...LOW CONFIDENCE IN PRECIP AND CIG FORECAST THIS PERIOD. RAW MODEL GUIDANCE FROM ALL MODELS WOULD SUGGEST MSP IS DONE WITH ANY MVFR CIGS THE REST OF THE PERIOD...SO TRENDED THE TAF THAT DIRECTION. LOTS OF UNCERTAINTY STILL WITH THE PRECIP POTENTIAL...BUT LATEST HRRR IS ACTUALLY AGREEING WITH THE SPCWRF/NMM IN THAT THE GREATEST THREAT MAY BE BETWEEN 10 AND 16Z...WITH NOT MUCH HAPPENING BEYOND THAT. /OUTLOOK FOR KMSP/ FRI...VFR. WINDS NW 15G25KT. SAT...VFR. WINDS NW 5-10KT. SUN...VFR. WINDS SE 10KT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...JPC LONG TERM...CLF AVIATION...MPG
AREA FORECAST DISCUSSION
NWS DULUTH MN
319 PM CDT TUE SEP 17 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 318 PM CDT TUE SEP 17 2013 MOISTURE CONTINUED TO INCREASE FROM WEST TO EAST ACROSS THE NORTHLAND TODAY. THE HIGH TO THE EAST WAS LOSING IT`S GRIP ON THE NORTHLAND. A SHORTWAVE WAS MOVING NORTHEAST OUT OF IOWA AND WILL COMBINE WITH WAA/MOISTURE ADVECTION TO CAUSE CLOUDS TO THICKEN ALL AREAS TONIGHT AND BRING A CHANCE FOR RAIN. THE RAP WAS DOING A GOOD JOB DEPICTING THE CLOUDS OVER OUR WESTERN CWA AND THEY SHOW INCREASING HUMIDITY ACROSS MUCH OF THE AREA BY 06Z. RAIN WILL BE POSSIBLE TONIGHT...AND WE INCREASED POPS OVER OUR FAR SOUTHERN CWA WHICH WILL HAVE THE BEST CHANCE AT SEEING UP TO A TENTH OF AN INCH OVERNIGHT. PWAT VALUES ARE EXPECTED TO RISE TO 1 TO 1.4 INCHES OVERNIGHT...AND WE EXPECT AREAS OF FOG TO FORM. MOST AREAS SHOULD NOT EXPERIENCE DENSE FOG...WITH THE EXCEPTION OF AREAS AROUND LAKE SUPERIOR LATE TONIGHT WHICH COULD SEE SOME PATCHY DENSE FOG. SURFACE DEWPOINTS ARE EXPECTED TO RISE INTO THE FIFTIES...AND WERE ALREADY 50 TO 55 FROM KINL TO KGPZ TO KAIT AND POINTS WEST. WE KEPT THE MENTION OF DRIZZLE TONIGHT FOR MOST AREAS...ALTHOUGH WE DON`T THINK IT WILL BE WIDESPREAD GIVEN UPSTREAM CONDITIONS. AREAS AROUND THE LAKE WILL HAVE A BETTER CHANCE AND IT COULD BE WIDESPREAD LATE TONIGHT INTO WEDNESDAY MORNING. STABILITY GRADUALLY LOWERS TONIGHT...AND WE ADDED A SLIGHT CHANCE FOR A THUNDERSTORM ACROSS THE SOUTH LATE. WAA WILL CONTINUE WEDNESDAY...WITH A SHORTWAVE RIDGE ALOFT MOVING THROUGH EARLY. WE HAVE A CHANCE FOR MORE SHOWERS/STORMS OVER ALL BUT FAR NORTHWEST AREAS ON WEDNESDAY...WITH THE BEST CHANCE OCCURRING EARLY. CLOUDS WILL SLOWLY DIMINISH OVER WESTERN AREAS...BUT SHOULD REMAIN THROUGH MOST OF THE DAY AROUND LAKE SUPERIOR AND OVER NORTHWEST WISCONSIN. HIGHS WILL RANGE FROM THE MID SIXTIES TO MID SEVENTIES ACROSS THE NORTHLAND...WARMEST SOUTHWEST...COOLEST AROUND LAKE SUPERIOR. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 318 PM CDT TUE SEP 17 2013 THE FIRST FEW DAYS OF THIS PERIOD WILL BE STORMY AND WET THEN BECOME CHILLY WITH A STRONG COLD FRONTAL PASSAGE. STRONG WAA THAT WILL BE ONGOING AHEAD OF AN APPROACHING COLD FRONT WILL CONTINUE CLOUDS WEDNESDAY NIGHT. KEPT IN CHANCE OF SHOWERS AND THUNDERSTORMS WEDNESDAY NIGHT...BUT VERY WARM MID LEVEL TEMPS MAY PROHIBIT STORM FORMATION. BOTH THE NAM AND GFS SHOW SURGE OF 7H 10+C TEMPS. MUCH BETTER CHANCE OF THUNDERSTORMS WILL BE THURSDAY AS A STRONG COLD FRONT APPROACHES THE AREA FROM THE WEST. THE NAM MAY BE A BIT FASTER...BUT THE MODELS ARE IN PRETTY GOOD AGREEMENT WITH MOVEMENT OF THE FRONT AND RESULTING QPF. DURING THE DAY THE ATMOSPHERE DESTABILIZES IN THE STRONG WAA REGIME AND WILL BE PRIMED FOR STORMS WHEN THE FRONT ARRIVES IN THE AFTERNOON/EARLY EVENING EVENING. LIL`S FORECAST DOWN TO -6 AND MUCAPES UP TO 2500 J/KG. AN EXTRA BOOST OF LIFT WILL BE PROVIDED BY AN UPPER LEVEL JET AND S/WV. STRONG COLD AIR WILL STREAM INTO THE REGION BEHIND THE FRONT FOR THE FRIDAY...BUT AS HIGH PRESSURE BUILDS INTO THE REGION THE WEEKEND WILL HAVE SUNSHINE BUT COOLER TEMPS. THIS WILL BE FOLLOWED BY ANOTHER LOW PRESSURE/COLD FRONT ON FROM EARLY THROUGH MID WEEK WITH A STRONG UPPER LEVEL TROF/CLOSED LOW. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1229 PM CDT TUE SEP 17 2013 MVFR CIGS WILL CONTINUE TO COVER THE WESTERN PART OF THE FORECAST AREA THIS AFTERNOON....AND THESE CLOUDS WILL SPREAD ACROSS THE REST OF THE AREA LATE THIS AFTERNOON AND EARLY EVENING. AFTER SUNSET CIGS WILL LOWER CONSIDERABLY AND MUCH OF THE AREA WILL BE IN IFR CONDITIONS..MAINLY DUE TO CIGS. HOWEVER...LATE TONIGHT AS MORE MOISTURE SURGES INTO THE AREA...PATCHY DENSE FOG AND RAIN WILL DEVELOP. && .PRELIMINARY POINT TEMPS/POPS... DLH 53 65 62 74 / 20 20 50 70 INL 54 74 60 71 / 10 10 50 60 BRD 58 77 65 74 / 20 20 50 60 HYR 54 73 62 76 / 40 40 40 70 ASX 54 71 59 78 / 30 30 40 70 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. && $$ SHORT TERM...MELDE LONG TERM...CLC AVIATION...CLC
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1258 PM CDT Tue Sep 17 2013 .SHORT TERM: (Through Late This Afternoon) Issued at 303 AM CDT Tue Sep 17 2013 Synoptic pattern over the region today will be dominated by broad WAA overrunning the cooler Canadian airmass that backed into the area Monday and overnight, which should certainly generate showers and a few thunderstorms today in the northwest half of the CWA. However, other than lead shortwave responsible for the light echoes in se MO attm (which is outrunning better moisture) and some 850mb theta-e advection vaguely focused over our n counties this morning, mechanisms for precip are rather ill-defined. The lack of a well-defined precip structure in the early morning regional radar imagery is indicating the rather diffuse nature of the lift. Plan to maintain broad PoP trends in current forecast with likely POPS in our northwest counties to chance PoPs in se MO, although specific numbers in a few locations will be changing to reflect latest radar trends. In our e counties couldn`t rule out a few sprinkles early today, but chances of measurable precip here look low attm. Will make a last minute call on this. Other concern for today is how warm to go on high temperatures, as residual cool air and scattered showers will at least partially offset warming due to the WAA. Still working on specifics but most areas should remain in the 70s, with the coolest temps over the northwest counties where clouds will be thickest and threat of showers should be highest. Truett .LONG TERM: (Tonight through Monday) Issued at 303 AM CDT Tue Sep 17 2013 Isolated to scattered SHRA/TSRA may continue percolating tonight due to isentropic ascent along the 300-305 K surface, with the highest precip chances across northeast MO and west central IL. Once the second of two shortwaves (which were located over KS and OK early this morning) and a warm front finally lift northeastward tonight, precipitation should also lift away from the area. Early morning water vapor imagery along and recent RUC 1.5 PVU analyses depicted a strong vort max located just off the northern CA coast. This feature is forecast to cross the Rockies and induce surface cyclogenesis over SD/ND tomorrow, although it will also influence conditions over MO/IL by producing weakly diffluent southwesterly flow aloft. Between general moistening of the air mass (PW values rise to around 1.7 inches by Wed night), increasing H7-H5 lapse rates, and nocturnal LLJ activity, it`s hard to rule out disorganized iso-sct precip for Wed and Wed night, particularly across the northern and northeastern CWA. In terms of the aforementioned low pressure system which will be moving along the US/Canadian border and into southern Canada by Thu night, models remain in general agreement with the overall pattern despite some differences after 20/00z regarding a piece of energy that breaks off near the base of the trough and then moves across MO on Fri night. The cold front is forecast to approach the CWA on Thu night and then move through on Fri/Fri night. Low level convergence with the front, large scale ascent ahead of the upper level trough axis, and favorable positioning beneath the right entrance region of a jet at H25 all support likely PoPs for Thu night and Fri across parts of the CWA. Precipitation is expected to end from northwest to southeast due to post-frontal subsidence. 17/00z runs of the ECMWF/GFS/GEM all agree that a surface high pressure center will build into the Great Lakes this weekend and that there will be some degree of upper ridging over the Plains ahead of the next progressive trough near the West Coast, but each model has a different take on the upper level pattern east of the Mississippi River with potential impacts for the MO/IL forecast. The GFS depicts a closed low over the OH valley, the GEM brings a tropical low northward from the Gulf of Mexico, and the ECMWF has a weak upper trough axis oriented from LA through GA and into VA. Since there is little confidence in any particular solution at this time, the forecast grids for Sat-Mon generally reflect the recommended CR initialization. Kanofsky && .AVIATION: (For the 18z TAFs through 18z Wednesday Afternoon) Issued at 1241 PM CDT Tue Sep 17 2013 Area of rain and lower CIGS/VSBYS over central Missouri will continue to spread into parts of eastern/northeast Missouri and west central Illinois. Not expecting flight conditions to fall below MVFR as the precipitation continues to weaken, but CIGS will likely occasionally fall below 2000FT. Expecting the weakening trend to continue through the weekend with little or no precip crossing the Mississippi river into southwest Illinois. Should see CIGS rise above 3000FT later this afternoon into the evening. Another wave of showers is expected to develop late tonight which could bring flight conditions back down to MVFR for early Wednesday morning. Specifics for KSTL: The area of rain over central Missouri is expected to continue weakening this afternoon, so am expecting little if any precipitation to reach Lambert. Should see VFR flight conditions continue at least through 06Z-08Z. However, another batch of rain is expected to develop over central Missouri late tonight, and this may bring CIGS down after 09Z. Confidence is low however, so have not lowered CIGS substantially in the TAF. Expect that if the CIGS do drop below VFR, conditions should improve after 12Z-14Z Wednesday. Carney && .LSX WATCHES/WARNINGS/ADVISORIES: MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
704 AM CDT Tue Sep 17 2013 .SHORT TERM: (Through Late This Afternoon) Issued at 303 AM CDT Tue Sep 17 2013 Synoptic pattern over the region today will be dominated by broad WAA overrunning the cooler Canadian airmass that backed into the area Monday and overnight, which should certainly generate showers and a few thunderstorms today in the northwest half of the CWA. However, other than lead shortwave responsible for the light echoes in se MO attm (which is outrunning better moisture) and some 850mb theta-e advection vaguely focused over our n counties this morning, mechanisms for precip are rather ill-defined. The lack of a well-defined precip structure in the early morning regional radar imagery is indicating the rather diffuse nature of the lift. Plan to maintain broad PoP trends in current forecast with likely POPS in our northwest counties to chance PoPs in se MO, although specific numbers in a few locations will be changing to reflect latest radar trends. In our e counties couldn`t rule out a few sprinkles early today, but chances of measurable precip here look low attm. Will make a last minute call on this. Other concern for today is how warm to go on high temperatures, as residual cool air and scattered showers will at least partially offset warming due to the WAA. Still working on specifics but most areas should remain in the 70s, with the coolest temps over the northwest counties where clouds will be thickest and threat of showers should be highest. Truett .LONG TERM: (Tonight through Monday) Issued at 303 AM CDT Tue Sep 17 2013 Isolated to scattered SHRA/TSRA may continue percolating tonight due to isentropic ascent along the 300-305 K surface, with the highest precip chances across northeast MO and west central IL. Once the second of two shortwaves (which were located over KS and OK early this morning) and a warm front finally lift northeastward tonight, precipitation should also lift away from the area. Early morning water vapor imagery along and recent RUC 1.5 PVU analyses depicted a strong vort max located just off the northern CA coast. This feature is forecast to cross the Rockies and induce surface cyclogenesis over SD/ND tomorrow, although it will also influence conditions over MO/IL by producing weakly diffluent southwesterly flow aloft. Between general moistening of the air mass (PW values rise to around 1.7 inches by Wed night), increasing H7-H5 lapse rates, and nocturnal LLJ activity, it`s hard to rule out disorganized iso-sct precip for Wed and Wed night, particularly across the northern and northeastern CWA. In terms of the aforementioned low pressure system which will be moving along the US/Canadian border and into southern Canada by Thu night, models remain in general agreement with the overall pattern despite some differences after 20/00z regarding a piece of energy that breaks off near the base of the trough and then moves across MO on Fri night. The cold front is forecast to approach the CWA on Thu night and then move through on Fri/Fri night. Low level convergence with the front, large scale ascent ahead of the upper level trough axis, and favorable positioning beneath the right entrance region of a jet at H25 all support likely PoPs for Thu night and Fri across parts of the CWA. Precipitation is expected to end from northwest to southeast due to post-frontal subsidence. 17/00z runs of the ECMWF/GFS/GEM all agree that a surface high pressure center will build into the Great Lakes this weekend and that there will be some degree of upper ridging over the Plains ahead of the next progressive trough near the West Coast, but each model has a different take on the upper level pattern east of the Mississippi River with potential impacts for the MO/IL forecast. The GFS depicts a closed low over the OH valley, the GEM brings a tropical low northward from the Gulf of Mexico, and the ECMWF has a weak upper trough axis oriented from LA through GA and into VA. Since there is little confidence in any particular solution at this time, the forecast grids for Sat-Mon generally reflect the recommended CR initialization. Kanofsky && .AVIATION: (For the 12z TAFs through 12z Wednesday Morning) Issued at 640 AM CDT Tue Sep 17 2013 As mentioned in the short term discussion, projected precip pattern across the CWA is a bit chaotic today. However, feel the greatest coverage of showers and scattered thunderstorms this morning will be in the zone of strongest WAA/isentropic lift over northwest parts of the CWA, and affecting the COU and UIN tafs. Have attempted to time onset of TEMPO shower groups to leading edge of echoes currently stretching from west central into southwest MO. Meanwhile, only a few hit and miss showers are expected for STL metro area tafs during the morning. Have omitted TS for now as radar/satellite imagery and latest guidance don`t offer any strong indications of an imminent threat at any of our forecast points. As far as ceilings are concerned...looks like MVFR and IFR that blankets the western half of Missouri will have a tough time migrating too far east due to strong easterly component to low level flow. Have held onto MVFR cigs 2-3kft at COU throughout the morning, with ceilings lifting aoa 3kft no later than midday. Ceilings elsewhere should be AOA 4kft today...rising to a mid cloud deck tonight. Specifics for KSTL: Ceilings around 4kft are expected today with a few hit and miss showers during the morning that should generally be on the light side. By tonight, forecast soundings indicate mid and high level cloudiness. Truett && .LSX WATCHES/WARNINGS/ADVISORIES: MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
325 AM CDT Tue Sep 17 2013 .SHORT TERM: (Through Late This Afternoon) Issued at 303 AM CDT Tue Sep 17 2013 Synoptic pattern over the region today will be dominated by broad WAA overrunning the cooler Canadian airmass that backed into the area Monday and overnight, which should certainly generate showers and a few thunderstorms today in the northwest half of the CWA. However, other than lead shortwave responsible for the light echoes in se MO attm (which is outrunning better moisture) and some 850mb theta-e advection vaguely focused over our n counties this morning, mechanisms for precip are rather ill-defined. The lack of a well-defined precip structure in the early morning regional radar imagery is indicating the rather diffuse nature of the lift. Plan to maintain broad PoP trends in current forecast with likely POPS in our northwest counties to chance PoPs in se MO, although specific numbers in a few locations will be changing to reflect latest radar trends. In our e counties couldn`t rule out a few sprinkles early today, but chances of measurable precip here look low attm. Will make a last minute call on this. Other concern for today is how warm to go on high temperatures, as residual cool air and scattered showers will at least partially offset warming due to the WAA. Still working on specifics but most areas should remain in the 70s, with the coolest temps over the northwest counties where clouds will be thickest and threat of showers should be highest. Truett .LONG TERM: (Tonight through Monday) Issued at 303 AM CDT Tue Sep 17 2013 Isolated to scattered SHRA/TSRA may continue percolating tonight due to isentropic ascent along the 300-305 K surface, with the highest precip chances across northeast MO and west central IL. Once the second of two shortwaves (which were located over KS and OK early this morning) and a warm front finally lift northeastward tonight, precipitation should also lift away from the area. Early morning water vapor imagery along and recent RUC 1.5 PVU analyses depicted a strong vort max located just off the northern CA coast. This feature is forecast to cross the Rockies and induce surface cyclogenesis over SD/ND tomorrow, although it will also influence conditions over MO/IL by producing weakly diffluent southwesterly flow aloft. Between general moistening of the air mass (PW values rise to around 1.7 inches by Wed night), increasing H7-H5 lapse rates, and nocturnal LLJ activity, it`s hard to rule out disorganized iso-sct precip for Wed and Wed night, particularly across the northern and northeastern CWA. In terms of the aforementioned low pressure system which will be moving along the US/Canadian border and into southern Canada by Thu night, models remain in general agreement with the overall pattern despite some differences after 20/00z regarding a piece of energy that breaks off near the base of the trough and then moves across MO on Fri night. The cold front is forecast to approach the CWA on Thu night and then move through on Fri/Fri night. Low level convergence with the front, large scale ascent ahead of the upper level trough axis, and favorable positioning beneath the right entrance region of a jet at H25 all support likely PoPs for Thu night and Fri across parts of the CWA. Precipitation is expected to end from northwest to southeast due to post-frontal subsidence. 17/00z runs of the ECMWF/GFS/GEM all agree that a surface high pressure center will build into the Great Lakes this weekend and that there will be some degree of upper ridging over the Plains ahead of the next progressive trough near the West Coast, but each model has a different take on the upper level pattern east of the Mississippi River with potential impacts for the MO/IL forecast. The GFS depicts a closed low over the OH valley, the GEM brings a tropical low northward from the Gulf of Mexico, and the ECMWF has a weak upper trough axis oriented from LA through GA and into VA. Since there is little confidence in any particular solution at this time, the forecast grids for Sat-Mon generally reflect the recommended CR initialization. Kanofsky && .AVIATION: (For the 06z TAFs through 06z Tuesday Night) Issued at 1154 PM CDT Mon Sep 16 2013 Mid and high clouds persist over area with mvfr cigs just west and southwest of forecast area as of 0430z. Will see the mvfr cigs slowly make their way to the northeast towards taf sites. Taf sites along I-70 corridor to see cigs lower to mvfr between 08z- 11z Tuesday. Otherwise, trying to figure out timing and coverage of showers and possibly a few thunderstorms. Activity over eastern KS, western MO to continue to develop and slide east, reaching central MO by 14z and west central IL by 19z. For now just kept vcnty shower mention. Not sure it will hold together and reach STL metro area, so kept those tafs dry for now. MVFR cigs to lift and scatter out by midday. As for winds, east winds to veer over time to the southeast, then eventually to the south as surface ridge moves off to the east. Specifics for KSTL: Mid and high clouds persist over area with mvfr cigs just west and southwest of forecast area as of 0430z. Will see the mvfr cigs slowly make their way to the northeast towards metro area. Cigs to lower to mvfr by 11z Tuesday. Otherwise, trying to figure out timing and coverage of showers and possibly a few thunderstorms. Activity over eastern KS, western MO to continue to develop and slide east. Not sure it will hold together and reach STL metro area, so kept KSTL dry for now. MVFR cigs to lift and scatter out by 16z Tuesday. As for winds, east winds to veer to the south by 16z Tuesday as surface ridge moves off to the east. Byrd && .LSX WATCHES/WARNINGS/ADVISORIES: MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
315 PM CDT TUE SEP 17 2013 .DISCUSSION... SHORT TERM CONCERNS ARE MAINLY CLOUD COVER INTO WEDNESDAY MORNING AND TEMPERATURES THE NEXT FEW DAYS. 12Z UPPER AIR CHARTS SHOWED THE FOLLOWING. AT 300 MB...JETSTREAM AXIS EXTENDED FROM BASE OF THE TROUGH RIGHT ALONG THE WEST COAST NORTHEASTWARD ACROSS THE ROCKIES AND INTO MANITOBA. AT 500 MB...ONE AREA OF GREATER THAN 30 METER HEIGHT FALLS EXTENDED FROM CANADA DOWN INTO MO. MORE SIGNIFICANT FALLS (60-90 METERS) WERE JUST AHEAD OF THE TROUGH OVER NORTHERN CA...SOUTHERN OR AND INTO NV. DECENT MOISTURE WAS NOTED FROM NRN MEXICO UP INTO THE CENTRAL PLAINS AT AND BELOW 700 MB. EARLY AFTN WATER VAPOR IMAGERY SHOWED DRYING MOVING ACROSS THE PLAINS BETWEEN THE TWO SHORTWAVES. EARLY AFTN SURFACE ANALYSIS SHOWED MODEST SOUTHERLY FLOW IN PLACE OVER THE AREA WITH DEWPOINTS IN THE 50S AND 60S. TONIGHT...EXPECT SOME DECREASE IN OVERALL CLOUD COVER. FORECAST SOUNDINGS SHOW SOME ELEVATED INSTABILITY THIS EVENING ALONG WITH DECENT MID LEVEL LAPSE RATES. LATEST RUNS OF THE RAP DEVELOP SOME PCPN ACROSS ABOUT THE EASTERN 1/2 OF MY AREA. 12Z GFS DID TOO. SO WILL INCLUDE A SMALL CHANCE FOR TSTMS PRIOR TO 09Z. WITH SUBSTANTIAL LOW LEVEL MOISTURE REMAINING IN PLACE AFTER HIGHER CLOUDS CLEAR OUT...HAVE SOME CONCERN THAT STRATUS MAY REFORM. WE MAY ALSO HAVE SOME FOG BUT IT APPEARS TO BE LESS OF A CONCERN FOR THE PUBLIC FORECAST DUE TO WINDS MOSTLY ABOVE 7 KNOTS. WEDNESDAY...SOUTHERLY FLOW WILL INCREASE AS MIXING DEPTH INCREASES THROUGH THE MORNING...WITH BREEZY/WINDY CONDITIONS BY AFTN. 850 MB TEMPERATURES WILL INCREASE SUBSTANTIALLY COMPARED TO TODAY (INTO THE 19-22 DEGREE CELSIUS RANGE BY 00Z THURSDAY)...SO HIGHS IN THE UPPER 80S TO AROUND 90 SEEM LIKELY. SYSTEM FOR WEDNESDAY NIGHT INTO THURSDAY SEEMS TO HAVE SLOWED DOWN A BIT SO DID MAKE SOME ADJUSTMENTS FOR PCPN TIMING IN THOSE PERIODS. COLD FRONT SHOULD ENTER OUR FAR NORTHWEST COUNTIES BETWEEN 06Z AND 09Z THURSDAY THEN EXIT THE SOUTHEAST COUNTIES BETWEEN 21Z THURSDAY AND 00Z FRIDAY. BOOSTED PCPN CHANCES A BIT FOR THURSDAY...BUT IT NOW APPEARS THE SYSTEM WILL EXIT SOONER THURSDAY NIGHT BASED ON A BLEND OF GFS/NAM/SREF/ECMWF/GEM. THE PERIOD FROM FRIDAY THROUGH SUNDAY SHOULD BE DRY...WITH HIGHS IN THE 70S TO AROUND 80. 500 MB TROUGH WILL BE SHIFTING EAST OF THE AREA FRIDAY...WITH RIDGING OVER THE ROCKIES AND ANOTHER TROUGH OFF THE WEST COAST. FLOW WILL BE PROGRESSIVE IN THIS PERIOD...WITH THE NEXT CHANCE OF PCPN MOVING IN BY SUNDAY NIGHT AS THE SYSTEM DIGS OVER THE ROCKIES. DIFLUENT FLOW ALONG WITH INCREASING MOISTURE AHEAD OF THE NEXT COLD FRONT SHOULD BRING SOME SHOWERS AND TSTMS FROM SUNDAY NIGHT THROUGH MONDAY NIGHT. MILLER && .AVIATION... 18Z TAFS FOR KOMA...KLNK...AND KOFK. IFR CONDITIONS CONTINUE ACROSS THE TAF SITES THIS AFTERNOON. SHOWERS HAVE CLEARED THE SITES...BUT CEILINGS ARE SLOW TO IMPROVE TODAY AS LOW-LEVEL MOISTURE LINGERS. INCREASED SOUTHERLY FLOW SHOULD HELP ERODE STRATUS DECK FROM THE WEST AND THE SOUTH FROM LATE AFTERNOON INTO THIS EVENING...BUT CANNOT RULE OUT THE POSSIBILITY THAT THE STRATUS DECK WILL SOCK IN LONGER THAN CURRENT FORECAST INDICATES. WINDS WILL REMAIN AROUND 10-12KT OVERNIGHT...WHICH SHOULD BE ENOUGH TO HELP ALLEVIATE WIND SHEAR CONCERNS...AND WHICH ALSO SHOULD BE ENOUGH TO DETER FOG FORMATION. EVEN SO...HAVE INCLUDED AN MVFR VIS GROUP AT ALL SITES LATE TONIGHT AS CLEARING OCCURS...AS GUIDANCE IS UNANIMOUSLY INDICATING AT LEAST SOME EXTENT OF REDUCED VIS. VIS WILL IMPROVE AS WINDS INCREASE THROUGH THE MORNING...WITH GUSTY SOUTH WINDS DEVELOPING BY MID-MORNING. MAYES && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
548 PM MDT WED SEP 18 2013 .AVIATION... 00Z TAF CYCLE MTS OCCASIONALLY OBSCURED. SCT CONVECTION TO PERSIST AND MOVE GENLY NORTHEAST TO EAST OVER NRN AND CENTRAL NM THROUGH 06Z...WITH ISOLD CONVECTION POSSIBLE INTO THE OVERNIGHT HOURS AS UPPER DISTURBANCE TRACKS EAST OVER THE REGION. LOCALIZED MVFR CIGS/VSBYS IN TSRA WILL BE POSSIBLE ALONG WITH SMALL HAIL AND SFC WND GUSTS TO 35KT. LOCAL MVFR CIGS POSSIBLE FROM THE CENTRAL MT CHAINS ACROSS THE EASTERN PLAINS AFT 06Z TO AROUND 15Z THURSDAY. SFC FRONT TO APPROACH FAR NE NM BY 15Z THURSDAY. && .PREV DISCUSSION...256 PM MDT WED SEP 18 2013... ANOTHER ACTIVE WX SCENARIO SHAPING UP OVER THE REGION FOR REMAINDER OF TODAY THRU THURSDAY. CIRA LAYERED TOTAL PW PRODUCT SHOWS ABUNDANT LOW/MID LEVEL MOISTURE ACROSS THE REGION WITH VERY DRY CONDITIONS ALOFT. VALUES ARE ON THE ORDER OF 130-160 PCT OF NORMAL. A THIN 30- 50 KT UPPER JET AXIS OVER NM AS SEEN ON THE LATEST AMDAR DATA IS INTERACTING WITH THE LOW LEVEL MOISTURE AND INSTABILITY TO PRODUCE A WELL DEFINED BAND OF THUNDERSTORMS OVER WESTERN AND NORTHERN NM. STEERING FLOWS ARE STRONG TODAY HOWEVER THE SHEAR AXIS IS ORIENTED IN THE DRXN OF STORM MOTION SO MORE LOCALLY HEAVY RAINFALL ON TAP. LATEST HRRR SHOWS THIS AREA OF SHOWERS AND STORMS PROPAGATING EVER SO SLOWLY EAST THIS EVENING INTO THE RIO GRANDE VALLEY AND NEARBY HIGH TERRAIN. HAVE RAISED POPS TO HIGH CHANCE AND LIKELY FOR CENTRAL NM. EVEN MORE ACTIVE CONDITIONS WILL TAKE SHAPE INTO THURSDAY NIGHT BUT MORE INTO THE EASTERN PLAINS. A LARGE UPPER TROUGH OVER THE PACIFIC NW WILL SLIDE EAST INTO THE GREAT PLAINS AND HELP DRIVE A SURFACE BACK DOOR FRONTAL BOUNDARY INTO NM. MEANWHILE...A VERY WELL DEFINED UPPER WAVE EMBEDDED ON THE BACK SIDE OF THE LARGE SCALE WAVE WILL SLIDE OVER NORTHERN NM AND HELP LIFT FOCUS OVER FRONT. CURRENT QPF VALUES ARE POTENTIALLY TOO LOW FOR THIS EVENT ACROSS THE EAST WHERE SUBSTANTIALLY MOISTURE REMAINS IN PLACE. FLOODING IS NOT EXPECTED HOWEVER SOME LOCALIZED IMPACTS ARE LIKELY IF THE RAIN FALLS OVER THE WRONG SPOT. ALSO RAISED POPS FOR THE EASTERN PLAINS THURSDAY NIGHT TO LIKELY. TEMPS THROUGH THIS PERIOD WILL COOL BELOW NORMAL FOR MUCH OF THE REGION...ESPECIALLY THE EAST. MODELS DO INDICATE STRONGER WESTERLIES AND DRIER AIR SHIFTING EAST INTO THE STATE FRIDAY THRU SUNDAY HOWEVER STRONG MOISTURE RECYCLING PROCESSES WILL STILL BE AT PLAY. LOW CLOUDS AND FOG ARE POSSIBLE ANY NIGHT ESPECIALLY IF SKIES CLEAR AND WINDS TAPER OFF. TEMPS WILL BE COOL OUT WEST WHERE MUCH DRIER DEWPOINTS WILL MOVE IN. THE EXTENDED PATTERN IS STILL HIGHLY UNCERTAIN SO MADE NO CHANGES. THE ECMWF PROGS A DEEP LARGE SCALE STATIONARY UPPER LOW OVER THE GREAT BASIN WITH A RELATIVELY ABUNDANT MONSOONAL MOISTURE TAP OVER NM. THE GFS HAS AN EVEN DEEPER TIGHTLY WOUND COLD UPPER LOW DRIVING EAST ACROSS THE CENTRAL ROCKIES THRU MID WEEK. GUYER && .FIRE WEATHER... SCATTERED WETTING THUNDERSTORMS FOUND ACROSS WESTERN AND NORTHERN AREAS WILL TRANSITION EASTWARD THIS EVENING BEFORE DIMINISHING SOME. DRIER AIR WILL EVENTUALLY FILL IN FROM WEST TO EAST LATER TONIGHT AND WILL SET THE STAGE FOR A DRIER WESTERN AND CENTRAL AREAS ON THURSDAY. A BACK DOOR COLD FRONT IS STILL EXPECTED FOR THURSDAY WITH EASTERN AREAS OBSERVING THAT INFLUENCE. THIS INCLUDES WETTING SHOWERS AND THUNDERSTORMS WHICH WOULD FAVOR MOST OF THE EASTERN PLAINS THURSDAY AFTERNOON INTO THE OVERNIGHT. MIXING HEIGHTS WILL INCREASE ACROSS THE MAJORITY OF THE AREA ALTHOUGH TRANSPORT WINDS WILL COME DOWN MOST AREAS SO VENTILATION RATES WILL LOWER PRETTY MUCH AREAWIDE. THE BACK DOOR COLD FRONT WILL PUSH THROUGH THE CENTRAL MOUNTAINS THURSDAY NIGHT AND MOST LIKELY MAKE IT TO THE AZ STATE LINE BY FRIDAY MORNING. MIXING DURING FRIDAY AFTERNOON SHOULD SET UP A CONVERGENCE BOUNDARY NEAR THE CONTINENTAL DIVIDE AND MOST LIKELY PROVIDE A FOCUS FOR THUNDERSTORMS THERE. THE ATMOSPHERE COULD BE TOO STABLE FOR SIGNIFICANT SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS CENTRAL AND EASTERN AREAS DUE TO RESIDUAL IMPACTS FROM THE COLD FRONT. HUMIDITY VALUES WILL BE UNSEASONABLY HIGH FRIDAY AFTERNOON. TEMPERATURES WILL BE COOLER THAN NORMAL CENTRAL AND EASTERN AREAS WHILE BEING NEAR NORMAL WEST OF THE CONTINENTAL DIVIDE. VENTILATION RATES WILL BE LOWEST EXTENDING FROM ZONE 109 NORTHEASTWARD OVER THE MIDDLE RIO GRANDE VALLEY AND AREAS TO THE LEE OF THE SANGRE DE CRISTOS. THE NEXT PACIFIC TROUGH WILL PLUNGE INTO THE FAR WESTERN US SATURDAY AND CONTINUE TO TRAVERSE ACROSS THE INTERMOUNTAIN WEST ON SUNDAY. MOISTURE WILL TRY TO SEEP UP FROM MEXICO AHEAD OF THIS TROUGH SO LOOK FOR UNSETTLED WEATHER ACROSS THE WEST ON SATURDAY TRANSITIONING SOME EASTWARD ON SUNDAY. WETTING RAIN WOULD CERTAINLY BE POSSIBLE ALTHOUGH NOT AS WIDESPREAD AS THE PREVIOUS WEEK. HUMIDITY IS EXPECTED TO TREND UP ACROSS THE WEST ON SATURDAY WHILE LOWER ACROSS THE EAST. ON SUNDAY...HUMIDITY IS EXPECTED TO LOWER AREAWIDE ALTHOUGH THIS COULD CHANGE. VENTILATION WILL INCREASE DURING THE WEEKEND THANKS TO STRONGER WEST/SOUTHWEST TRANSPORT WIND. CONFIDENCE IS PRETTY GOOD THAT A PACIFIC TROUGH WILL IMPACT THE AREA BUT STILL NOT TOTALLY SURE ABOUT HOW MUCH MOISTURE WILL SEEP UP FROM THE SOUTH AND FEED THE TROUGH. SURFACE WIND SHOULD ALSO INCREASE DURING THE WEEKEND PERIOD. ANOTHER PACIFIC TROUGH IS EXPECTED TO AFFECT THE WESTERN US BY THE MIDDLE OF NEXT WEEK. THE LONG RANGE MODELS DIFFER SOMEWHAT IN THE EXTENSION SOUTHWARD OF THE TROUGH BUT EITHER WAY IMPACT POTENTIAL WOULD INCREASE BY MID NEXT WEEK. DEPENDING ON HOW THE TROUGH COMES IN...ADDITIONAL WETTING RAIN WOULD BE POSSIBLE. CONDITIONS FOLLOWING THE TROUGH PASSAGE COULD LEAD TO THE MOUNTAINS FIRST BIG FREEZE OF THE FALL SEASON SO WILL BE WATCHING THAT AS THAT WOULD BEGIN THE CURING PROCESS TO THE ABUNDANT FUELS THAT HAVE GREENED UP THIS SUMMER. 50 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
620 AM EDT TUE SEP 17 2013 .SYNOPSIS... HIGH PRESSURE BUILDS OVER THE REGION TODAY BEHIND A COLD FRONT. THE HIGH WILL REMAIN OVER THE REGION INTO THE END OF THE WEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 620 AM TUESDAY... WITH THE SURFACE FRONT NOW WELL SOUTH OF CENTRAL NORTH CAROLINA... DRIER MID-LEVEL AIR HAD MOVED INTO THE AREA FROM THE NORTH ON WATER VAPOR IMAGERY. PRECIPITABLE WATER VALUES FALL TO A HALF-INCH OR LESS BY TONIGHT...AS K INDICES FALL INTO MOSTLY NEGATIVE VALUES. FOR TODAY...THE SURFACE GRADIENT TIGHTENS AS HIGH PRESSURE BUILDS SOUTH...WITH BOTH THE NAM AND THE GFS BUFR SOUNDINGS SUGGESTING... WITH MIXING...SURFACE WIND GUSTS FROM THE UPPER TEENS TO LOWER 20S KTS COURTESY OF THE GRADIENT AND A 925MB WIND OF 20 TO 25KT EARLY THIS MORNING. GUSTINESS SHOULD WANE DURING THE AFTERNOON AS THE 925MB WINDS DIMINISH TO 10 TO 15KT BY 00Z WEDNESDAY. THE 00Z TUESDAY UPPER-AIR ANALYSIS SHOWED DECENT 850MB MOISTURE ACROSS MUCH OF THE EASTERN SEABOARD...AND THE 00Z NAM BUFR SOUNDINGS SUGGESTED DECENT 850MB MOISTURE IN PLACE PROVIDING FOR THE LIKELIHOOD OF AT LEAST SCATTERED CU/SC DURING THE DAY. ON THE OTHER HAND...THE GFS IS MUCH DRIER AND CAPPED AT 850MB...AND THE LATEST NAM AND RAP BOTH ARE A LITTLE LESS ROBUST WITH THE LOW-LEVEL MOISTURE...INCREASING THE POTENTIAL FOR SOME HIGH-BASED CU OR SC LATER IN THE DAY AFTER MORNING CLOUDS ERODE. THE CANADIAN CLOUD COVER MODEL IS SIMILAR... AND LEANING THIS PARTLY TO MOSTLY CLOUDY CONDITIONS DURING THE VERY EARLY MORNING SHOULD IMPROVE TO CONSIDERABLE SUNSHINE...WITH AREAS OF PARTLY SUNNY CONDITIONS DEVELOPING THIS AFTERNOON AS SOME 850MB MOISTURE MOVES IN FROM THE EAST AND NORTHEAST. 1000-850MB THICKNESSES SUGGEST HIGHS...OVERALL...NEAR THE COOLER GFS MOS GUIDANCE...FOR MAXES MOSTLY IN THE MID TO UPPER 70S. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... AS OF 230 AM TUESDAY... HIGH PRESSURE REMAINS IN PLACE THROUGH...AND BEYOND...THIS SHORT-TERM PERIOD. THERE REMAINS A MODEST SURFACE GRADIENT TONIGHT... SO DESPITE THE STRENGTH OF THE HIGH THERE SHOULD BE ENOUGH MIXING UNDER THE INVERSION THAT WINDS SHOULD NOT GO COMPLETELY CALM...OR COMPLETELY CALM FOR LONG. THE CLOUD FORECAST IS A LITTLE CHALLENGING...AS THE GFS IN PARTICULAR ADVECTS SOME STRATOCU IN THE LOW-LEVEL EASTERLY FLOW TOWARD THE COASTAL PLAIN LATE...WITH BOTH THE NAM AND THE GFS...ALONG WITH THE CANADIAN CLOUD COVER MODEL... SUGGESTIVE OF SOME MOSTLY THIN CIRRUS LATE FROM THE WEST AND NORTHWEST. STAYED CLOSE TO GUIDANCE LOWS...LEANING MORE TOWARD THE GFS AND ITS BIAS-CORRECTED MINS...FOR LOWS FROM THE UPPER 40S TOWARD KTDF...KHNZ...AND KLHZ TO THE MID 50S OVER MUCH OF THE SANDHILLS AND THE SOUTHERN COASTAL PLAIN. RECORD LOWS ARE ABOUT 5 DEGREES BELOW FORECAST LOWS AT KGSO...KRDU...AND KFAY. WEDNESDAY...AHEAD OF AN INCREASE IN POTENTIAL VORTICITY ON THE 1.5PVU SURFACE THAT BOTH THE NAM AND GFS FORECAST WEDNESDAY NIGHT... AREAS OF HIGH CLOUDS ARE FORECAST WHICH ALSO SHOW UP ON THE CANADIAN CLOUD COVER MODEL. WITH THAT LEVEL OF CONSISTENCY AMONG THE GUIDANCE...WILL HAVE SKIES BECOMING PARTLY SUNNY IN THE GRIDDED FORECAST DURING THE AFTERNOON FOR MOST LOCATIONS TURNING MOSTLY CLEAR DURING THE EVENING. AGAIN...SUBTLE DISCREPANCIES OCCUR BETWEEN THE NAM AND GFS THAT RESULT IN A CHALLENGING CLOUD COVER FORECAST FOR OVERNIGHT WEDNESDAY NIGHT. THE NAM IS MUCH MORE AGGRESSIVE IN INCREASING MID-LEVEL MOISTURE OVERNIGHT AT OR JUST ABOVE 500MB WITH THE PASSAGE OF THE MODEST WAVE ON THE 1.5PVU SURFACE...WHILE THE GFS IGNORES THIS AND WOULD IMPLY LIMITED CLOUD COVER. THIS HAS AN IMPACT ON THE LOW TEMPERATURE FORECAST. UNDER A LIGHT WIND WITH THE SURFACE RIDGE AXIS OVERHEAD...LOWS HAVE THE POTENTIAL TO BE COLDER THAN WHAT SHOULD OCCUR TONIGHT. ON THE OTHER HAND...BOTH THE NAM AND THE GFS MOS GUIDANCE ARE WARMER AT MOST EVERY LOCATION FOR WEDNESDAY NIGHT COMPARED TO TONIGHT. THE GFS IS JUST ABOUT AS STRONG AS THE NAM WITH ITS WAVE ON THE 1.5PVU SURFACE OVERNIGHT WEDNESDAY...SO WILL ANTICIPATE AT LEAST A FEW CLOUDS MOVING THROUGH. WILL STILL FORECAST A FEW 40S WEDNESDAY NIGHT BUT CONFINE THEM TO BASICALLY ALONG THE VIRGINIA BORDER COUNTIES...SHOWING A DEGREE OR TWO INCREASE IN LOWS IN MOST OTHER LOCATIONS FOR MOSTLY LOWER TO MID 50S. 1000-850MB THICKNESSES ARE ABOUT 8M HIGHER WEDNESDAY COMPARED TO TODAY...BUT WITH A FEW HIGH CLOUDS EXPECTED DURING THE AFTERNOON...THE MAX TEMPERATURE FORECAST FOR WEDNESDAY IS BASICALLY PERSISTENCE FROM TODAY. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 305 AM TUESDAY... THU THROUGH FRI NIGHT: DEEP LAYER RIDGINGWILL CONTROL THE WEATHER PATTERN OVER CENTRAL NC THIS PERIOD. RETURN FLOW WILL DEVELOP AROUND THE CONTINENTAL POLAR SURFACE HIGH FORECAST TO BE CENTERED OVER THE MIDDLE ATLANTIC STATES AT THE START OF THE PERIOD. THE COMBO OF THIS RETURN FLOW AND SIGNIFICANT CP AIR MASS MODIFICATION BY A LATE SUMMER SUN ANGLE WILL YIELD NEAR AVERAGE TEMPS FOR MID SEPTEMBER ON THU. FURTHER WARMING WILL TAKE PLACE FRI IN STRENGTHENING RETURN FLOW AND SUBSIDENCE BENEATH A 317 DM H7 RIDGE AXIS OVER THE SOUTHERN APPALACHIANS. HIGHS IN THE MIDDLE TO UPPER 80S...OR A FEW DEGREES WARMER THAN WHAT FORECAST LOW LEVEL THICKNESSES - WHICH HAVE YIELDED A COOL BIAS IN RECENT WEEKS - WOULD SUGGEST. LOWS...WITH GOOD RADIATIONAL COOLING ASSOCIATED WITH MOSTLY CLEAR AND CALM IN THE RIDGE AXIS...ARE FORECAST ON THE COOL SIDE OF GUIDANCE - IN LINE WITH CLIMO FOR PROJECTED LL THICKNESSES IN THE 1380 TO AROUND 1390 METER RANGE. SAT THROUGH MON: THE FIRST IN A SERIES OF A FEW STRONG AND PROGRESSIVE UPPER LOWS/TROUGHS FORECAST TO MIGRATE EASTWARD ACROSS THE NORTHERN TIER OF THE CONUS/SOUTHERN CANADA WILL PROPEL AN ACCOMPANYING SURFACE COLD FRONT FROM THE TN VALLEY EARLY SAT...TO THE SPINE OF THE APPALACHIAN CHAIN BY SUN MORNING...WITH PRECEDING PRE-FRONTAL TROUGHING IN THE LEE OF THE APPALACHIANS. MEDIUM RANGE GUIDANCE...ASIDE FROM THE DISCOUNTED 00Z/17TH GFS SOLUTION...HAS COME INTO EXCELLENT AGREEMENT REGARDING THIS EVOLUTION AND ASSOCIATED FRONTAL PASSAGE THROUGH CENTRAL NC ON SUN. THERE HAS BEEN A TREND TOWARD A STRONGER SOUTHERN STREAM PORTION OF THE LONGWAVE TROUGH ALOFT...WHICH WILL LIKELY SUPPORT SOME SORT OF SURFACE CYCLOGENESIS FROM THE NW CARIBBEAN TO THE SW ATLANTIC LATE IN THE WEEKEND INTO EARLY NEXT WEEK. GIVEN THE PROGRESSIVE NATURE OF THE FLOW ALOFT...HOWEVER...ANY SUCH DEVELOPMENT WOULD BE TOO FAR SOUTH AND EAST TO AFFECT OUR AREA...WHICH IS WHY THE 00Z/17TH GFS SOLUTION WAS DISCOUNTED AS NOTED ABOVE. SENSIBLE WEATHER HIGHLIGHTS WILL FEATURE SCATTERED SHOWERS AND ISOLATED THUNDER IN AN ALBEIT ONLY WEAKLY UNSTABLE WARM SECTOR... PARTICULARLY INVOF THE LEE TROUGH OVER THE PIEDMONT...SAT AFTERNOON AND NIGHT. SCATTERED TO NUMEROUS SHOWERS AND STORMS AREA-WIDE... AMIDST AGAIN ONLY WEAK INSTABILITY...ARE THEN FAVORED WITH THE SLOW PASSAGE OF THE SURFACE COLD FRONT ON SUN. POST-FRONTAL SURFACE HIGH PRESSURE WILL FOLLOW FOR MON...THOUGH WITH A LINGERING CHANCE OF A SHOWER OR STORM OVER SE NC...INVOF THE SLOW-MOVING FRONT. TEMPERATURES WILL TREND FROM THE MIDDLE...TO PERHAPS A FEW UPPER 80S IN THE COASTAL PLAIN...SAT...TO AROUND SEASONAL AVERAGES AROUND 80 DEGREES ON MON. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 620 AM TUESDAY... VFR CONDITIONS ARE EXPECTED THROUGH THE 12Z VALID TAF PERIOD. VERY PATCHY MVFR CLOUDS CONTINUED MAINLY TOWARD KGSB AND A FEW OF THESE COULD STILL BRIEFLY AFFECT KFAY BEFORE DRIER AIR MOVING IN FROM THE NORTH RESULTS IN A HIGH PROBABILITY OF VFR CONDITIONS. AS HIGH PRESSURE BUILDS SOUTH...THE GRADIENT AROUND THE HIGH SHOULD RESULT IN GUSTY WINDS...WITH SEVERAL GUSTS EXPECTED FROM THE UPPER TEENS TO LOWER 20S KNOTS BY MID-MORNING THROUGH MID-AFTERNOON BEFORE SOME OF THE GUSTINESS WANES LATE. 925MB WINDS DIMINISH TO 10 TO 15KT BY 00Z WEDNESDAY. UNDER VFR CONDITIONS TONIGHT...EAST-NORTHEAST WINDS OFF OF THE SURFACE COULD INCREASE TO THE UPPER TEENS TO NEAR 25KT BY 03Z AT THE INVERSION...STRONGEST TOWARD KFAY AND LIGHTEST MORE TOWARD THE RIDGE AXIS TOWARD KGSO AND KINT. BEYOND THE 12Z VALID TAF PERIOD...LOCAL MVFR CONDITIONS IN LIGHT FOG ARE POSSIBLE WEDNESDAY NIGHT...AND DEPENDING ON ANY MID-LEVEL CLOUD COVER...VERY LOCALLY IFR CONDITIONS COULD OCCUR TOWARD KRWI. SIMILAR CONDITIONS ARE POSSIBLE DURING THE REST OF THE WORK WEEK. BY SATURDAY...THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS AHEAD OF LOW PRESSURE AND A SURFACE FRONT. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...DJF SHORT TERM...DJF LONG TERM...MWS AVIATION...DJF
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1233 PM CDT TUE SEP 17 2013 .UPDATE... ISSUED AT 1226 PM CDT TUE SEP 17 2013 SOLID SC CLOUD DECK CONTINUES TO OVERSPREAD FA EARLY THIS AFTERNOON. CLOUDS STILL LOOK FAIRLY SOLID WITH NO BREAKS AT THIS POINT. BASED ON CURRENT TEMPERATURE TRENDS WILL NEED TO LOWER MAXIMUM TEMPERATURES SEVERAL DEGREES ACROSS THE BOARD AND STILL HOPE CIGS BREAK ENOUGH FOR SOME LATE AFTERNOON SOLAR. NO OTHER CHANGES PLANNED. UPDATE ISSUED AT 931 AM CDT TUE SEP 17 2013 MADE SOME SLIGHT CLOUD TREND ADJUSTMENTS BASED ON CURRENT SATELLITE TRENDS OTHERWISE CURRENT FORECAST LOOKING GOOD SO FAR AND NO OTHER CHANGES MADE. UPDATE ISSUED AT 656 AM CDT TUE SEP 17 2013 LEADING EDGE OF LOW CLOUDS IS NOW ALONG A COOPERSTOWN TO WAHPETON LINE AND CONTINUES TO MOVE NORTH-NORTHEAST AROUND 35 MPH. BACK EDGE OF CLOUD DECK IS A BIT FARTHER WEST THAN PREVIOUS FORECAST...SO ADJUSTED SKY GRIDS TO REFLECT LATEST OBSERVATIONS. AS A RESULT... EXPECT ALL BUT THE FAR NORTHWEST FORECAST AREA TO BECOME MOSTLY CLOUDY BY LATE MORNING INTO THE EARLY AFTERNOON. LATEST HRRR SUGGESTS THE SUN MAY PEAK OUT FOR A COUPLE HOURS ALONG THE VALLEY FLOOR BEFORE SUNSET. OTHERWISE...AREAS TO THE EAST WILL REMAIN CLOUDY FOR MUCH OF THE NIGHT. ALSO DECREASED TEMPERATURES A FEW DEGREES ACROSS THE NORTHERN VALLEY INTO NORTHWEST MN TO ACCOUNT FOR MORE EXPANSIVE CLOUDS. REST OF THE FORECAST IN GOOD SHAPE WITH NO MAJOR CHANGES AT THIS TIME. && .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 414 AM CDT TUE SEP 17 2013 CHALLENGES INCLUDE CLOUD COVER AND TEMPERATURES TODAY/TONIGHT AND THEN PRECIPITATION CHANCES/SEVERE POTENTIAL WEDNESDAY NIGHT INTO THURSDAY. GFS/NAM/ECMWF/GEM IN GOOD OVERALL AGREEMENT AND WILL USE A BLENDED SOLUTION FOR THIS FORECAST PACKAGE. FOR TODAY...MOIST SOUTHERLY FLOW BETWEEN THE SURFACE HIGH ACROSS THE GREAT LAKES AND DEVELOPING LOW IN THE LEE OF THE NORTHERN ROCKIES WILL ADVECT LOW CLOUDS CURRENTLY ACROSS EASTERN SD/SOUTHERN MN/ NE/IA NORTHWARD ACROSS THE FORECAST AREA. RAP 925 HPA RH SUGGESTS THESE CLOUDS WILL MOVE INTO THE SOUTHERN FORECAST AREA BY 12 UTC AND THEN ALONG AND EAST OF THE VALLEY BY THIS AFTERNOON. AREAS WITH PERSISTENT CLOUD COVER NOT LIKELY TO RISE ABOVE 70 DEGREES. LOWER TO MID 70S ARE POSSIBLE ACROSS THE DEVILS LAKE BASIN AND NORTHERN VALLEY WHERE MORE SUNSHINE IS EXPECTED. TODAY WILL ALSO BE BREEZY TO LOCALLY WINDY WITH 30 KTS IN THE MIXED LAYER. THIS SHOULD TRANSLATE TO SURFACE WINDS FROM 15 TO 25 MPH WITH GUSTS UP TO 30 MPH. LOW CLOUDS WILL BE VERY SLOW TO DISSIPATE OVERNIGHT...ESPECIALLY ACROSS THE EASTERN FORECAST AREA. MODEL SOUNDINGS SUGGEST THE POSSIBILITY OF SOME LIGHT DRIZZLE...BUT GIVEN LOW SENSIBLE WEATHER IMPACT AND COVERAGE UNCERTAINTY...WILL NOT INCLUDE IN CURRENT GRIDS. SOUTHERLY WINDS WILL REMAIN ELEVATED BETWEEN 10 AND 15 MPH WITH LOW TEMPERATURES GENERALLY IN THE 50S. STRONG POSITIVE THERMAL ADVECTION IN THE WARM SECTOR OF AN APPROACHING PACIFIC WAVE WILL RESULT IN TEMPERATURES WELL ABOVE NORMAL ON WEDNESDAY. AFTERNOON HIGHS WILL CLIMB INTO THE MID 70S TO LOWER 80S. SOUTHERLY WIND WILL NOT BE AS STRONG AS TODAY. MOST OF THE DAY SHOULD BE DRY WITH ONLY A CHANCE FOR AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS THE DEVILS LAKE BASIN. .LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY) ISSUED AT 414 AM CDT TUE SEP 17 2013 A STRONG SURFACE LOW WILL TRACK ACROSS ND WEDNESDAY EVENING AND INTO THE CENTRAL/NORTHERN VALLEY BY 06 UTC THURSDAY. WARM TEMPERATURES ALOFT MAY LIMIT CONVECTIVE INITIATION...BUT THE COMBINATION OF MLCAPE UP TO 2000 J/KG...PWATS AROUND 1.5 INCHES... AN APPROACHING SURFACE COLD FRONT AND INCREASING BULK SHEAR FROM A 300 HPA JET STREAK SHOULD RESULT IN THUNDERSTORM DEVELOPMENT ACROSS EASTERN ND INTO NORTHWEST MN. SOME STORMS NEAREST TO THE SURFACE LOW MAY BECOME SEVERE AND THIS IS HIGHLIGHTED IN THE SPC DAY 2 CONVECTIVE OUTLOOK WHICH SHOWS A SLIGHT RISK ALONG AND NORTHWEST OF A LINE FROM CARRINGTON TO GRAND FORKS TO HALLOCK. TOO EARLY TO ADD SEVERE WORDING TO THE GRIDS...BUT SOMETHING TO WATCH. WITH THE EXCEPTION OF SOME WRAP-AROUND SHOWERS LATE WEDNESDAY NIGHT INTO THURSDAY ACROSS THE NORTHERN FORECAST AREA...MOST OF EASTERN ND/NORTHWEST MN WILL BE DRY-SLOTTED ONCE CONVECTION MOVES INTO CENTRAL AND EAST CENTRAL MN BY 12 UTC THURSDAY. STRONG WESTERLY WINDS WILL FOLLOW IN THE WAKE OF THE SURFACE FRONT... ALONG WITH A MUCH COOLER AIR MASS. HIGH TEMPERATURES THURSDAY WILL RANGE FROM THE LOW 60S ACROSS THE DEVILS LAKE BASIN TO THE LOW 70S ACROSS WEST CENTRAL MN LAKES COUNTRY. WEST WINDS WILL RANGE FROM 15 TO 25 MPH. FRIDAY THROUGH MONDAY...THE WEEK WILL END QUIET AND COOL WITH NORTHWESTERLY FLOW BEHIND THE DEPARTING TROUGH AND HIGH PRESSURE BUILDING INTO THE PLAINS. A FEW SHOWERS MAY LINGER OVER LAKE OF THE WOODS AREA BUT OTHERWISE THINK WE WILL BE DRY THROUGH FRIDAY AND INTO SATURDAY. THE WEEKEND WILL SEE A SLOW WARMING TREND AS SOUTHERLY WINDS RETURN. THE MAIN UPPER TROUGH WILL REMAIN OVER THE WESTERN CONUS THROUGH THE END OF THE PERIOD BUT MODELS ALL SHOW SIGNS OF A LEAD SHORTWAVE MOVING FROM THE NORTHERN ROCKIES THROUGH THE PLAINS LATE SUNDAY AND INTO MONDAY. KEPT FAIRLY HIGH POPS GOING FOR SUNDAY NIGHT AND MONDAY AS A WEAK SFC TROUGH AXIS/FRONTAL BOUNDARY MOVES THROUGH. TEMPS WILL BE A FEW DEGREES LOWER ON MONDAY BUT STILL AROUND SEASONAL AVERAGES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1226 PM CDT TUE SEP 17 2013 MVFR CIGS EXPECTED TO IMPACT ALL TAF SITES FOR THE REMAINDER OF THE AFTERNOON AND INTO THE EVENING WITH A SLOW EROSION OF THE STRATUS DECK FROM WEST TO EAST. GUSTY SOUTHERLY WINDS WILL DIMINISH THIS EVENING. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...VOELKER SHORT TERM...ROGERS LONG TERM...ROGERS/JR AVIATION...VOELKER
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
933 AM CDT TUE SEP 17 2013 .UPDATE... ISSUED AT 931 AM CDT TUE SEP 17 2013 MADE SOME SLIGHT CLOUD TREND ADJUSTMENTS BASED ON CURRENT SATELLITE TRENDS OTHERWISE CURRENT FORECAST LOOKING GOOD SO FAR AND NO OTHER CHANGES MADE. UPDATE ISSUED AT 656 AM CDT TUE SEP 17 2013 LEADING EDGE OF LOW CLOUDS IS NOW ALONG A COOPERSTOWN TO WAHPETON LINE AND CONTINUES TO MOVE NORTH-NORTHEAST AROUND 35 MPH. BACK EDGE OF CLOUD DECK IS A BIT FARTHER WEST THAN PREVIOUS FORECAST...SO ADJUSTED SKY GRIDS TO REFLECT LATEST OBSERVATIONS. AS A RESULT... EXPECT ALL BUT THE FAR NORTHWEST FORECAST AREA TO BECOME MOSTLY CLOUDY BY LATE MORNING INTO THE EARLY AFTERNOON. LATEST HRRR SUGGESTS THE SUN MAY PEAK OUT FOR A COUPLE HOURS ALONG THE VALLEY FLOOR BEFORE SUNSET. OTHERWISE...AREAS TO THE EAST WILL REMAIN CLOUDY FOR MUCH OF THE NIGHT. ALSO DECREASED TEMPERATURES A FEW DEGREES ACROSS THE NORTHERN VALLEY INTO NORTHWEST MN TO ACCOUNT FOR MORE EXPANSIVE CLOUDS. REST OF THE FORECAST IN GOOD SHAPE WITH NO MAJOR CHANGES AT THIS TIME. && .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 414 AM CDT TUE SEP 17 2013 CHALLENGES INCLUDE CLOUD COVER AND TEMPERATURES TODAY/TONIGHT AND THEN PRECIPITATION CHANCES/SEVERE POTENTIAL WEDNESDAY NIGHT INTO THURSDAY. GFS/NAM/ECMWF/GEM IN GOOD OVERALL AGREEMENT AND WILL USE A BLENDED SOLUTION FOR THIS FORECAST PACKAGE. FOR TODAY...MOIST SOUTHERLY FLOW BETWEEN THE SURFACE HIGH ACROSS THE GREAT LAKES AND DEVELOPING LOW IN THE LEE OF THE NORTHERN ROCKIES WILL ADVECT LOW CLOUDS CURRENTLY ACROSS EASTERN SD/SOUTHERN MN/ NE/IA NORTHWARD ACROSS THE FORECAST AREA. RAP 925 HPA RH SUGGESTS THESE CLOUDS WILL MOVE INTO THE SOUTHERN FORECAST AREA BY 12 UTC AND THEN ALONG AND EAST OF THE VALLEY BY THIS AFTERNOON. AREAS WITH PERSISTENT CLOUD COVER NOT LIKELY TO RISE ABOVE 70 DEGREES. LOWER TO MID 70S ARE POSSIBLE ACROSS THE DEVILS LAKE BASIN AND NORTHERN VALLEY WHERE MORE SUNSHINE IS EXPECTED. TODAY WILL ALSO BE BREEZY TO LOCALLY WINDY WITH 30 KTS IN THE MIXED LAYER. THIS SHOULD TRANSLATE TO SURFACE WINDS FROM 15 TO 25 MPH WITH GUSTS UP TO 30 MPH. LOW CLOUDS WILL BE VERY SLOW TO DISSIPATE OVERNIGHT...ESPECIALLY ACROSS THE EASTERN FORECAST AREA. MODEL SOUNDINGS SUGGEST THE POSSIBILITY OF SOME LIGHT DRIZZLE...BUT GIVEN LOW SENSIBLE WEATHER IMPACT AND COVERAGE UNCERTAINTY...WILL NOT INCLUDE IN CURRENT GRIDS. SOUTHERLY WINDS WILL REMAIN ELEVATED BETWEEN 10 AND 15 MPH WITH LOW TEMPERATURES GENERALLY IN THE 50S. STRONG POSITIVE THERMAL ADVECTION IN THE WARM SECTOR OF AN APPROACHING PACIFIC WAVE WILL RESULT IN TEMPERATURES WELL ABOVE NORMAL ON WEDNESDAY. AFTERNOON HIGHS WILL CLIMB INTO THE MID 70S TO LOWER 80S. SOUTHERLY WIND WILL NOT BE AS STRONG AS TODAY. MOST OF THE DAY SHOULD BE DRY WITH ONLY A CHANCE FOR AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS THE DEVILS LAKE BASIN. .LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY) ISSUED AT 414 AM CDT TUE SEP 17 2013 A STRONG SURFACE LOW WILL TRACK ACROSS ND WEDNESDAY EVENING AND INTO THE CENTRAL/NORTHERN VALLEY BY 06 UTC THURSDAY. WARM TEMPERATURES ALOFT MAY LIMIT CONVECTIVE INITIATION...BUT THE COMBINATION OF MLCAPE UP TO 2000 J/KG...PWATS AROUND 1.5 INCHES... AN APPROACHING SURFACE COLD FRONT AND INCREASING BULK SHEAR FROM A 300 HPA JET STREAK SHOULD RESULT IN THUNDERSTORM DEVELOPMENT ACROSS EASTERN ND INTO NORTHWEST MN. SOME STORMS NEAREST TO THE SURFACE LOW MAY BECOME SEVERE AND THIS IS HIGHLIGHTED IN THE SPC DAY 2 CONVECTIVE OUTLOOK WHICH SHOWS A SLIGHT RISK ALONG AND NORTHWEST OF A LINE FROM CARRINGTON TO GRAND FORKS TO HALLOCK. TOO EARLY TO ADD SEVERE WORDING TO THE GRIDS...BUT SOMETHING TO WATCH. WITH THE EXCEPTION OF SOME WRAP-AROUND SHOWERS LATE WEDNESDAY NIGHT INTO THURSDAY ACROSS THE NORTHERN FORECAST AREA...MOST OF EASTERN ND/NORTHWEST MN WILL BE DRY-SLOTTED ONCE CONVECTION MOVES INTO CENTRAL AND EAST CENTRAL MN BY 12 UTC THURSDAY. STRONG WESTERLY WINDS WILL FOLLOW IN THE WAKE OF THE SURFACE FRONT... ALONG WITH A MUCH COOLER AIR MASS. HIGH TEMPERATURES THURSDAY WILL RANGE FROM THE LOW 60S ACROSS THE DEVILS LAKE BASIN TO THE LOW 70S ACROSS WEST CENTRAL MN LAKES COUNTRY. WEST WINDS WILL RANGE FROM 15 TO 25 MPH. FRIDAY THROUGH MONDAY...THE WEEK WILL END QUIET AND COOL WITH NORTHWESTERLY FLOW BEHIND THE DEPARTING TROUGH AND HIGH PRESSURE BUILDING INTO THE PLAINS. A FEW SHOWERS MAY LINGER OVER LAKE OF THE WOODS AREA BUT OTHERWISE THINK WE WILL BE DRY THROUGH FRIDAY AND INTO SATURDAY. THE WEEKEND WILL SEE A SLOW WARMING TREND AS SOUTHERLY WINDS RETURN. THE MAIN UPPER TROUGH WILL REMAIN OVER THE WESTERN CONUS THROUGH THE END OF THE PERIOD BUT MODELS ALL SHOW SIGNS OF A LEAD SHORTWAVE MOVING FROM THE NORTHERN ROCKIES THROUGH THE PLAINS LATE SUNDAY AND INTO MONDAY. KEPT FAIRLY HIGH POPS GOING FOR SUNDAY NIGHT AND MONDAY AS A WEAK SFC TROUGH AXIS/FRONTAL BOUNDARY MOVES THROUGH. TEMPS WILL BE A FEW DEGREES LOWER ON MONDAY BUT STILL AROUND SEASONAL AVERAGES. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 656 AM CDT TUE SEP 17 2013 FRONT EDGE OF MVFR CLOUD DECK NOW EXTENDS FROM KS32 TO KBWP AND IS MOVING NORTH-NORTHEAST AROUND 30 KTS. ADJUSTED TIMING OF CEILINGS FOR 12 UTC TAFS BASED ON LATEST OBSERVATIONAL TRENDS. THINK KDVL WILL BE RIGHT ON THE EDGE OF THE CLOUDS THROUGH THE DAY...SO WILL KEEP IT SCATTERED FOR NOW. SOUTHERLY WINDS WILL BE ELEVATED THROUGH THE PERIOD WITH AFTERNOON GUSTS AROUND 25 KTS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...VOELKER SHORT TERM...ROGERS LONG TERM...ROGERS/JR AVIATION...ROGERS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
656 AM CDT TUE SEP 17 2013 .UPDATE... ISSUED AT 656 AM CDT TUE SEP 17 2013 LEADING EDGE OF LOW CLOUDS IS NOW ALONG A COOPERSTOWN TO WAHPETON LINE AND CONTINUES TO MOVE NORTH-NORTHEAST AROUND 35 MPH. BACK EDGE OF CLOUD DECK IS A BIT FARTHER WEST THAN PREVIOUS FORECAST...SO ADJUSTED SKY GRIDS TO REFLECT LATEST OBSERVATIONS. AS A RESULT... EXPECT ALL BUT THE FAR NORTHWEST FORECAST AREA TO BECOME MOSTLY CLOUDY BY LATE MORNING INTO THE EARLY AFTERNOON. LATEST HRRR SUGGESTS THE SUN MAY PEAK OUT FOR A COUPLE HOURS ALONG THE VALLEY FLOOR BEFORE SUNSET. OTHERWISE...AREAS TO THE EAST WILL REMAIN CLOUDY FOR MUCH OF THE NIGHT. ALSO DECREASED TEMPERATURES A FEW DEGREES ACROSS THE NORTHERN VALLEY INTO NORTHWEST MN TO ACCOUNT FOR MORE EXPANSIVE CLOUDS. REST OF THE FORECAST IN GOOD SHAPE WITH NO MAJOR CHANGES AT THIS TIME. && .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 414 AM CDT TUE SEP 17 2013 CHALLENGES INCLUDE CLOUD COVER AND TEMPERATURES TODAY/TONIGHT AND THEN PRECIPITATION CHANCES/SEVERE POTENTIAL WEDNESDAY NIGHT INTO THURSDAY. GFS/NAM/ECMWF/GEM IN GOOD OVERALL AGREEMENT AND WILL USE A BLENDED SOLUTION FOR THIS FORECAST PACKAGE. FOR TODAY...MOIST SOUTHERLY FLOW BETWEEN THE SURFACE HIGH ACROSS THE GREAT LAKES AND DEVELOPING LOW IN THE LEE OF THE NORTHERN ROCKIES WILL ADVECT LOW CLOUDS CURRENTLY ACROSS EASTERN SD/SOUTHERN MN/ NE/IA NORTHWARD ACROSS THE FORECAST AREA. RAP 925 HPA RH SUGGESTS THESE CLOUDS WILL MOVE INTO THE SOUTHERN FORECAST AREA BY 12 UTC AND THEN ALONG AND EAST OF THE VALLEY BY THIS AFTERNOON. AREAS WITH PERSISTENT CLOUD COVER NOT LIKELY TO RISE ABOVE 70 DEGREES. LOWER TO MID 70S ARE POSSIBLE ACROSS THE DEVILS LAKE BASIN AND NORTHERN VALLEY WHERE MORE SUNSHINE IS EXPECTED. TODAY WILL ALSO BE BREEZY TO LOCALLY WINDY WITH 30 KTS IN THE MIXED LAYER. THIS SHOULD TRANSLATE TO SURFACE WINDS FROM 15 TO 25 MPH WITH GUSTS UP TO 30 MPH. LOW CLOUDS WILL BE VERY SLOW TO DISSIPATE OVERNIGHT...ESPECIALLY ACROSS THE EASTERN FORECAST AREA. MODEL SOUNDINGS SUGGEST THE POSSIBILITY OF SOME LIGHT DRIZZLE...BUT GIVEN LOW SENSIBLE WEATHER IMPACT AND COVERAGE UNCERTAINTY...WILL NOT INCLUDE IN CURRENT GRIDS. SOUTHERLY WINDS WILL REMAIN ELEVATED BETWEEN 10 AND 15 MPH WITH LOW TEMPERATURES GENERALLY IN THE 50S. STRONG POSITIVE THERMAL ADVECTION IN THE WARM SECTOR OF AN APPROACHING PACIFIC WAVE WILL RESULT IN TEMPERATURES WELL ABOVE NORMAL ON WEDNESDAY. AFTERNOON HIGHS WILL CLIMB INTO THE MID 70S TO LOWER 80S. SOUTHERLY WIND WILL NOT BE AS STRONG AS TODAY. MOST OF THE DAY SHOULD BE DRY WITH ONLY A CHANCE FOR AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS THE DEVILS LAKE BASIN. .LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY) ISSUED AT 414 AM CDT TUE SEP 17 2013 A STRONG SURFACE LOW WILL TRACK ACROSS ND WEDNESDAY EVENING AND INTO THE CENTRAL/NORTHERN VALLEY BY 06 UTC THURSDAY. WARM TEMPERATURES ALOFT MAY LIMIT CONVECTIVE INITIATION...BUT THE COMBINATION OF MLCAPE UP TO 2000 J/KG...PWATS AROUND 1.5 INCHES... AN APPROACHING SURFACE COLD FRONT AND INCREASING BULK SHEAR FROM A 300 HPA JET STREAK SHOULD RESULT IN THUNDERSTORM DEVELOPMENT ACROSS EASTERN ND INTO NORTHWEST MN. SOME STORMS NEAREST TO THE SURFACE LOW MAY BECOME SEVERE AND THIS IS HIGHLIGHTED IN THE SPC DAY 2 CONVECTIVE OUTLOOK WHICH SHOWS A SLIGHT RISK ALONG AND NORTHWEST OF A LINE FROM CARRINGTON TO GRAND FORKS TO HALLOCK. TOO EARLY TO ADD SEVERE WORDING TO THE GRIDS...BUT SOMETHING TO WATCH. WITH THE EXCEPTION OF SOME WRAP-AROUND SHOWERS LATE WEDNESDAY NIGHT INTO THURSDAY ACROSS THE NORTHERN FORECAST AREA...MOST OF EASTERN ND/NORTHWEST MN WILL BE DRY-SLOTTED ONCE CONVECTION MOVES INTO CENTRAL AND EAST CENTRAL MN BY 12 UTC THURSDAY. STRONG WESTERLY WINDS WILL FOLLOW IN THE WAKE OF THE SURFACE FRONT... ALONG WITH A MUCH COOLER AIR MASS. HIGH TEMPERATURES THURSDAY WILL RANGE FROM THE LOW 60S ACROSS THE DEVILS LAKE BASIN TO THE LOW 70S ACROSS WEST CENTRAL MN LAKES COUNTRY. WEST WINDS WILL RANGE FROM 15 TO 25 MPH. FRIDAY THROUGH MONDAY...THE WEEK WILL END QUIET AND COOL WITH NORTHWESTERLY FLOW BEHIND THE DEPARTING TROUGH AND HIGH PRESSURE BUILDING INTO THE PLAINS. A FEW SHOWERS MAY LINGER OVER LAKE OF THE WOODS AREA BUT OTHERWISE THINK WE WILL BE DRY THROUGH FRIDAY AND INTO SATURDAY. THE WEEKEND WILL SEE A SLOW WARMING TREND AS SOUTHERLY WINDS RETURN. THE MAIN UPPER TROUGH WILL REMAIN OVER THE WESTERN CONUS THROUGH THE END OF THE PERIOD BUT MODELS ALL SHOW SIGNS OF A LEAD SHORTWAVE MOVING FROM THE NORTHERN ROCKIES THROUGH THE PLAINS LATE SUNDAY AND INTO MONDAY. KEPT FAIRLY HIGH POPS GOING FOR SUNDAY NIGHT AND MONDAY AS A WEAK SFC TROUGH AXIS/FRONTAL BOUNDARY MOVES THROUGH. TEMPS WILL BE A FEW DEGREES LOWER ON MONDAY BUT STILL AROUND SEASONAL AVERAGES. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 656 AM CDT TUE SEP 17 2013 FRONT EDGE OF MVFR CLOUD DECK NOW EXTENDS FROM KS32 TO KBWP AND IS MOVING NORTH-NORTHEAST AROUND 30 KTS. ADJUSTED TIMING OF CEILINGS FOR 12 UTC TAFS BASED ON LATEST OBSERVATIONAL TRENDS. THINK KDVL WILL BE RIGHT ON THE EDGE OF THE CLOUDS THROUGH THE DAY...SO WILL KEEP IT SCATTERED FOR NOW. SOUTHERLY WINDS WILL BE ELEVATED THROUGH THE PERIOD WITH AFTERNOON GUSTS AROUND 25 KTS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...ROGERS SHORT TERM...ROGERS LONG TERM...ROGERS/JR AVIATION...ROGERS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
414 AM CDT TUE SEP 17 2013 .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 414 AM CDT TUE SEP 17 2013 CHALLENGES INCLUDE CLOUD COVER AND TEMPERATURES TODAY/TONIGHT AND THEN PRECIPITATION CHANCES/SEVERE POTENTIAL WEDNESDAY NIGHT INTO THURSDAY. GFS/NAM/ECMWF/GEM IN GOOD OVERALL AGREEMENT AND WILL USE A BLENDED SOLUTION FOR THIS FORECAST PACKAGE. FOR TODAY...MOIST SOUTHERLY FLOW BETWEEN THE SURFACE HIGH ACROSS THE GREAT LAKES AND DEVELOPING LOW IN THE LEE OF THE NORTHERN ROCKIES WILL ADVECT LOW CLOUDS CURRENTLY ACROSS EASTERN SD/SOUTHERN MN/ NE/IA NORTHWARD ACROSS THE FORECAST AREA. RAP 925 HPA RH SUGGESTS THESE CLOUDS WILL MOVE INTO THE SOUTHERN FORECAST AREA BY 12 UTC AND THEN ALONG AND EAST OF THE VALLEY BY THIS AFTERNOON. AREAS WITH PERSISTENT CLOUD COVER NOT LIKELY TO RISE ABOVE 70 DEGREES. LOWER TO MID 70S ARE POSSIBLE ACROSS THE DEVILS LAKE BASIN AND NORTHERN VALLEY WHERE MORE SUNSHINE IS EXPECTED. TODAY WILL ALSO BE BREEZY TO LOCALLY WINDY WITH 30 KTS IN THE MIXED LAYER. THIS SHOULD TRANSLATE TO SURFACE WINDS FROM 15 TO 25 MPH WITH GUSTS UP TO 30 MPH. LOW CLOUDS WILL BE VERY SLOW TO DISSIPATE OVERNIGHT...ESPECIALLY ACROSS THE EASTERN FORECAST AREA. MODEL SOUNDINGS SUGGEST THE POSSIBILITY OF SOME LIGHT DRIZZLE...BUT GIVEN LOW SENSIBLE WEATHER IMPACT AND COVERAGE UNCERTAINTY...WILL NOT INCLUDE IN CURRENT GRIDS. SOUTHERLY WINDS WILL REMAIN ELEVATED BETWEEN 10 AND 15 MPH WITH LOW TEMPERATURES GENERALLY IN THE 50S. STRONG POSITIVE THERMAL ADVECTION IN THE WARM SECTOR OF AN APPROACHING PACIFIC WAVE WILL RESULT IN TEMPERATURES WELL ABOVE NORMAL ON WEDNESDAY. AFTERNOON HIGHS WILL CLIMB INTO THE MID 70S TO LOWER 80S. SOUTHERLY WIND WILL NOT BE AS STRONG AS TODAY. MOST OF THE DAY SHOULD BE DRY WITH ONLY A CHANCE FOR AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS THE DEVILS LAKE BASIN. .LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY) ISSUED AT 414 AM CDT TUE SEP 17 2013 A STRONG SURFACE LOW WILL TRACK ACROSS ND WEDNESDAY EVENING AND INTO THE CENTRAL/NORTHERN VALLEY BY 06 UTC THURSDAY. WARM TEMPERATURES ALOFT MAY LIMIT CONVECTIVE INITIATION...BUT THE COMBINATION OF MLCAPE UP TO 2000 J/KG...PWATS AROUND 1.5 INCHES... AN APPROACHING SURFACE COLD FRONT AND INCREASING BULK SHEAR FROM A 300 HPA JET STREAK SHOULD RESULT IN THUNDERSTORM DEVELOPMENT ACROSS EASTERN ND INTO NORTHWEST MN. SOME STORMS NEAREST TO THE SURFACE LOW MAY BECOME SEVERE AND THIS IS HIGHLIGHTED IN THE SPC DAY 2 CONVECTIVE OUTLOOK WHICH SHOWS A SLIGHT RISK ALONG AND NORTHWEST OF A LINE FROM CARRINGTON TO GRAND FORKS TO HALLOCK. TOO EARLY TO ADD SEVERE WORDING TO THE GRIDS...BUT SOMETHING TO WATCH. WITH THE EXCEPTION OF SOME WRAP-AROUND SHOWERS LATE WEDNESDAY NIGHT INTO THURSDAY ACROSS THE NORTHERN FORECAST AREA...MOST OF EASTERN ND/NORTHWEST MN WILL BE DRY-SLOTTED ONCE CONVECTION MOVES INTO CENTRAL AND EAST CENTRAL MN BY 12 UTC THURSDAY. STRONG WESTERLY WINDS WILL FOLLOW IN THE WAKE OF THE SURFACE FRONT... ALONG WITH A MUCH COOLER AIR MASS. HIGH TEMPERATURES THURSDAY WILL RANGE FROM THE LOW 60S ACROSS THE DEVILS LAKE BASIN TO THE LOW 70S ACROSS WEST CENTRAL MN LAKES COUNTRY. WEST WINDS WILL RANGE FROM 15 TO 25 MPH. FRIDAY THROUGH MONDAY...THE WEEK WILL END QUIET AND COOL WITH NORTHWESTERLY FLOW BEHIND THE DEPARTING TROUGH AND HIGH PRESSURE BUILDING INTO THE PLAINS. A FEW SHOWERS MAY LINGER OVER LAKE OF THE WOODS AREA BUT OTHERWISE THINK WE WILL BE DRY THROUGH FRIDAY AND INTO SATURDAY. THE WEEKEND WILL SEE A SLOW WARMING TREND AS SOUTHERLY WINDS RETURN. THE MAIN UPPER TROUGH WILL REMAIN OVER THE WESTERN CONUS THROUGH THE END OF THE PERIOD BUT MODELS ALL SHOW SIGNS OF A LEAD SHORTWAVE MOVING FROM THE NORTHERN ROCKIES THROUGH THE PLAINS LATE SUNDAY AND INTO MONDAY. KEPT FAIRLY HIGH POPS GOING FOR SUNDAY NIGHT AND MONDAY AS A WEAK SFC TROUGH AXIS/FRONTAL BOUNDARY MOVES THROUGH. TEMPS WILL BE A FEW DEGREES LOWER ON MONDAY BUT STILL AROUND SEASONAL AVERAGES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1110 PM CDT MON SEP 16 2013 THE MVFR CLOUDS IN SOUTHERN SD SHOULD SLOWLY ADVECT TO THE NORTH AND EAST OVERNIGHT. HAVE MENTIONED SOME MVFR CIGS INTO FAR/BJI LATE TONIGHT INTO TUE MORNING. THESE CLOUDS COULD AFFECT AREAS A BIT FURTHER NORTH AS WELL...BUT FOR NOW HAVE KEPT ANY CIGS IN THE VFR RANGE. THERE COULD BE RE-DEVELOPMENT OF CIGS TUE NIGHT AFTER 00Z WED...AND HAVE MENTIONED THIS AS WELL. WINDS COULD GUST OVER 25KT IN MOST AREAS BY LATE TUE MORNING AND CONTINUE THROUGH AFTERNOON... WITH 25-40KT IN THE MIXED LAYER THROUGH TUE MORNING. CAN/T RULE OUT SOME LOW LEVEL WIND SHEAR LATE TONIGHT IF DE-COUPLING IS STRONGER THAN FORECAST...WITH 40KT AT TIMES NEAR 925MB IN THE 06-12Z TIME RANGE. WILL NOT MENTION LLWS IN THE TAF WITH LIMITED CONFIDENCE...BUT SOMETHING TO KEEP IN MIND. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ SHORT TERM...ROGERS LONG TERM...ROGERS/JR AVIATION...DK
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1025 PM EDT WED SEP 18 2013 .SYNOPSIS... AN INCREASE IN MOISTURE AND A SERIES OF WEAK UPPER LEVEL DISTURBANCES WILL RESULT IN A CHANCE OF SHOWERS AND A FEW THUNDERSTORMS TO THE REGION TONIGHT AND THURSDAY. A BETTER CHANCE OF THUNDERSTORMS WILL DEVELOP FRIDAY AFTERNOON INTO FRIDAY NIGHT AS A COLD FRONT MOVES ACROSS THE AREA FROM THE NORTHWEST. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... THERE ARE CONCERNS ON BOTH SIDES OF THE CWA TONIGHT...REQUIRING A FEW CHANGES TO THE GRIDS. IN THE EASTERN CWA...A LARGE EXPANSE OF STRATUS HAS DEVELOPED. AS ADDITIONAL MOISTURE MOVES NORTH INTO THE CWA...THIS IS EXPECTED TO CONTINUE THROUGH THE NIGHT...WITH CEILINGS LOWERING. SKY GRIDS HAVE BEEN ADJUSTED...THOUGH IT WAS NOT QUITE POSSIBLE TO INCREASE TO 100 PERCENT WHEN MOST OF THE CWA STILL IS MOSTLY CLEAR...OR EVEN BROKEN ON THE EDGES OF THE STRATUS. HOWEVER...THE FAR EASTERN CWA SHOULD REMAIN CLOUDY THROUGH THE NIGHT. ATTENTION IS ALSO TURNING TO CONVECTION NEAR CHICAGO...WHICH SEVERAL RUNS OF THE HRRR AND RAP INDICATE WILL MAKE IT INTO THE NORTHWEST CWA BY THE EARLY MORNING HOURS. THERE IS A GRADIENT OF ELEVATED INSTABILITY THAT WILL SHIFT GRADUALLY EAST THROUGH THE NIGHT...ALLOWING A TRAJECTORY (IF THE CONVECTION HOLDS TOGETHER) THAT WOULD EVENTUALLY MOVE THROUGH INDIANA AND INTO THE ILN FORECAST AREA. POPS HAVE BEEN INCREASED IN THE NORTHWESTERN CWA WITH THUNDER INTRODUCED. TIMING THE CONVECTION OUT WOULD HAVE IT INTO THE MERCER/WAYNE COUNTY AREAS BY 07Z...AND FURTHER FORECAST UPDATES WILL BE NECESSARY IF THIS LOOKS MORE LIKELY TO OCCUR. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... ISENTROPIC LIFT DEVELOPS ACROSS THE AREA THURSDAY WITH WARM FRONT LIFTING NORTHEAST INTO THE GREAT LAKES. WILL CONTINUE CHANCE POPS WITH THE BEST THREAT ACRS THE NW WHERE MOST FAVORABLE INSTBY WILL EXIST. IN WARM AIR ADVECTION PATTERN EXPECT TEMPERATURES TO RUN AROUND 5 DEGREES ABOVE NORMAL...WITH HIGHS RANGING FROM NEAR 80 NE TO THE MID 80S SW. WITH THE PASSAGE OF THE WARM FRONT AND RIDGING IN MID LEVELS THERE WILL BE A LACK OF SIGNIFICANT FORCING THURSDAY NIGHT. HAVE DIMINISHED POPS FROM THE SOUTH WITH A SLIGHT CHANCE EARLY TO DRY OVERNIGHT. SRLY SFC WINDS WILL STAY UP AT 5 TO 10 MPH ALONG WITH CLOUD COVER WILL KEEP TEMPERATURES ON THE WARMER SIDE. EXPECT OVERNIGHT LOWS TO RANGE FROM THE MID 60S SE TO THE UPPER 60S NW. PROGRESSIVE/DIGGING MID LEVEL TROF TO MOVE INTO THE WESTERN GREAT LAKES/UPR MS VLY FRIDAY AND THE GREAT LAKES FRIDAY NIGHT. ASSOCIATED SFC COLD FRONT TO PUSH EAST THRU ILN/S FA FRIDAY NIGHT/EARLY SATURDAY. NAM SOLN IS DEPICTING A PRE-FRONTAL TROF WITH MODERATE INSTBY INTO THE WEST LATE FRIDAY AFTN. GIVEN THE HIGHER RESOLUTION THIS LOOKS REASONABLE. WILL CONTINUE TO RAMP UP POPS TO LKLY LATE IN THE DAY FRIDAY AND THEN CATEGORICAL FRIDAY NIGHT ACRS THE ENTIRE REGION AS THE FRONT PUSHES IN. WILL CONTINUE TO HIGHLIGHT POTENTIAL FOR LOCALLY DAMAGING WINDS AND SOME HAIL WITH SOME OF THE STRONGER STORMS FRIDAY AFTN/EARLY EVENING. THIS WILL BE DEPENDENT ON INSTBY AND WILL LIMIT AREAL EXTENT TO OVER THE WESTERN COUNTIES. GIVEN WAA AHEAD OF THE FRONT...EXPECT TEMPS TO BE CLOSE TO 10 DEGREES ABOVE NORMAL WITH HIGHS ON FRIDAY RANGING FROM THE MID/UPR 80S SE TO THE LOWER 80S FAR NW. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... A COLD FRONT IS EXPECTED TO BE LOCATED THROUGH THE EASTERN PARTS OF THE FA SATURDAY MORNING. SHOWERS AND SOME THUNDERSTORMS WILL LINGER BEHIND THE FRONT ON SATURDAY AS THE UPPER TROUGH SWINGS THROUGH THE OHIO RIVER VALLEY REGION. WIDELY SCATTERED SHOWERS MAY LINGER IN THE SE ON SUNDAY. LATEST ECMWF IS MORE PROGRESSIVE WITH THE FRONT AND FUTURE FORECASTS MAY NEED TO CUT BACK ON PRECIPITATION SATURDAY AFTERNOON AND SUNDAY. ON MONDAY...HIGH PRESSURE WILL BUILD IN FROM THE NORTH. COULD SEE ENOUGH MOISTURE FROM THE LOW MOVING UP THE COAST TO PRODUCE ISOLATED SHOWERS IN THE EXTREME EAST. AFTER MONDAY...SURFACE HIGH PRESSURE EXTENDING INTO THE REGION FROM THE NE WILL BRING DRY WEATHER AND MILD TEMPERATURES. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... SLIGHTLY UNSETTLED WEATHER CONDITIONS WILL CONTINUE THROUGH THE NEXT SEVERAL DAYS. MOISTURE CONTINUES TO INCREASE OVER THE OHIO VALLEY...RESULTING IN INCREASING CLOUDS...AND THE POSSIBILITY FOR ISOLATED SHOWERS TO DEVELOP AT JUST ABOUT ANY TIME. THIS WILL NOT BE INCLUDED SPECIFICALLY IN THE TAFS OVERNIGHT...AS THE COVERAGE WILL BE VERY LOW FOR THE MOST PART. THE BIGGEST CONCERN OVERNIGHT IS THE POTENTIAL FOR STRATUS DEVELOPMENT. THERE IS HIGH CONFIDENCE IN A THICKENING OF THE LOW-LEVEL MOISTURE OVERNIGHT...WITH UPSTREAM CONDITIONS ALREADY INDICATING MVFR CEILINGS ACROSS MOST OF KENTUCKY. THESE MVFR CLOUDS ARE EXPECTED TO LOWER INTO THE IFR REGION AS THEY OVERSPREAD THE TAF SITES. THE FOG FORECAST IS SOMEWHAT UNCERTAIN...BUT MVFR TO IFR VISIBILITIES ARE EXPECTED...AND THERE IS SOME POTENTIAL FOR LOWER CONDITIONS THAN THAT. CEILINGS WILL BE SLOW TO LIFT ON THURSDAY...BUT CONDITIONS WILL BECOME MORE FAVORABLE FOR SHOWERS AND POSSIBLY THUNDERSTORMS...MAINLY FOR THE CINCINNATI AND DAYTON TAF SITES. VCSH HAS BEEN INCLUDED IN THE TAFS FOR THIS TIME FRAME. OUTLOOK...THUNDERSTORMS WILL BE POSSIBLE FROM FRIDAY AFTERNOON THROUGH SATURDAY MORNING. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...AR NEAR TERM...HATZOS SHORT TERM...AR LONG TERM...PARKER AVIATION...HATZOS
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1214 PM CDT TUE SEP 17 2013 .DISCUSSION... SEE 18Z AVIATION DISCUSSION. && .AVIATION... RAP AND HRRR KEEP THINGS KIND OF DRY THIS AFTN WITH JUST SOME SPOTTY SHOWERS EXPECTED OVER THE SOUTHWEST THIRD OF THE REGION AND OVER THE EXTREME NE PART OF THE AREA. STRONGER WINDS JUST OFF THE SURFACE ARE MIXING DOWN SO ADDED WIND GUSTS FOR THIS AFTN. MODELS HINT AT SOME MID LEVEL CLOUDS SCOOTING ACROSS THE AREA OVERNIGHT. TOMORROW LOOKS SIMILAR TO TODAY WITH SCT CLOUDS BENEATH A CANOPY OF BKN CIRRUS. 43 && .PREV DISCUSSION... /ISSUED 1028 AM CDT TUE SEP 17 2013/ UPDATE... VERY LITTLE -SHRA ACTIVITY THIS MORNING...ANY MAINLY CONFINED TO THE COASTAL COUNTIES SURROUNDING MATAGORDA BAY. RIDGING WILL MAINTAIN GENERAL SUBSIDENCE THROUGH AT LEAST MID-DAY. KLCH SOUNDING DISPLAYING QUITE A BIT OF MID-LEVEL DRY AIR (1.42 INCH PW) THAT WILL LIKELY BE ADVECTED OVER THE AREA WITHIN PERSISTENT EASTERLY FLOW THROUGH THE DAY. ONCE SURFACE TEMPERATURES ACHIEVE THE UPPER 80S...WIDELY SCATTERED CONVECTIVE ACTIVITY SHOULD BEGIN TO BLOSSOM FURTHER INLAND. ALL OF THE SHORT TERM HI-REZ PROGS SHOW NOTHING OF SIGNIFICANCE...POSSIBLE MORE COVERAGE OVER THE FAR NORTH BUT...WITHIN THIS AIR MASS THERE IS JUST A MODEST CHANCE THAT 20% OF THE AREA WILL EXPERIENCE MID-LATE AFTERNOON SHOWERS/ISOLATED STORMS. 17/12Z MID-UPPER LEVEL ANALYSIS VERIFIES RIDGING AT ALL MANDATORY LEVELS...RIBBON OF HIGHER MID-LAYER MOISTURE OVER NORTHEASTERN TEXAS (ALSO SEEN ON GOES SOUNDER PWS) MAY AID IN THE LATE DAY DEVELOPMENT OF NE`ERN CWA -SHRA/-TSRA ACTIVITY. ALL AND ALL...A QUIET GO OF THINGS GOING INTO MID-WEEK. 31 PREV DISCUSSION... /ISSUED 645 AM CDT TUE SEP 17 2013/ AVIATION... WITH A SLIGHTLY DRIER AIR MASS MOVING INTO SOUTHEAST TEXAS TODAY...THINK THE AREA WILL SEE A LITTLE LESS COVERAGE THAT WHAT WAS AROUND DURING THE AFTERNOON THROUGH EARLY EVENING HOURS ON MONDAY. CARRIED VCSH 20-23Z FOR IAH AND HOU AND SGR IN THE 12Z TAFS...BUT LATEST TREND IN THE HIGH RES MODELS POINTS TOWARD VERY LITTLE AFTERNOON THROUGH EARLY EVENING COVERAGE. THE MAJORITY OF THE AREA TODAY WILL SEE SCT/BKN CIRRUS WITH SOME LOW LEVEL CU (FEW/SCT) DEVELOPMENT. LIGHT E/NE WINDS THIS MORNING EXPECTED TO BECOME E/ESE DURING THE MID/LATE MORNING HOURS THEN SE LATE IN THE AFTERNOON PEAKING AT AROUND 10 KNOTS. LIGHT AND VARIABLE WINDS TONIGHT THROUGH SUNRISE WEDNESDAY MORNING. 42 PREV DISCUSSION... /ISSUED 404 AM CDT TUE SEP 17 2013/ DISCUSSION... THE UPPER LEVEL RIDGE IS CENTERED NEARLY OVERHEAD THIS MORNING WHILE INGRID HAS NOW DISSIPATED INTO A REMNANT LOW ACROSS THE HIGHER TERRAIN OF MEXICO. SHOWER ACTIVITY OFFSHORE IS LESS THAN THE PREVIOUS FEW MORNINGS WITH SOME SCATTERED SHOWERS MOVING INLAND NEAR MATAGORDA BAY AND AN ISOLATED SHOWER OR TWO TRYING TO FORM NEAR GALVESTON BAY. TODAY LOOKS TO BE A NEAR REPEAT OF YESTERDAY WITH HIGHS IN THE LOW TO MID 90S AND A FEW SCATTERED SHOWERS OR THUNDERSTORMS DEVELOPING ACROSS THE SOUTHERN HALF OF THE REGION. A TROPICAL WAVE ACROSS THE WESTERN CARIBBEAN SEA WILL PUSH INTO THE YUCATAN PENINSULA TODAY AND EMERGE OVER THE BAY OF CAMPECHE ON WEDNESDAY. MODELS KEEP THIS SYSTEM AS A FAIRLY DISORGANIZED AREA OF LOW PRESSURE THROUGH THE END OF THE WEEK AND ANY MOVEMENT TOWARD SOUTHEAST TEXAS WILL BE HAMPERED BY AN APPROACHING COLD FRONT WHICH WILL REACH THE COAST EARLY SATURDAY MORNING. THIS FRONT IS ASSOCIATED WITH AN UPPER TROUGH CURRENTLY ACROSS THE PACIFIC NORTHWEST WHICH WILL BUILD INTO THE CENTRAL PLAINS BY THE END OF THE WEEK. MOISTURE FROM THE REMNANTS OF INGRID AND MANUEL WILL BE PULLED NORTHWARD INTO TEXAS AHEAD OF THIS SYSTEM AND WILL ALLOW FOR SHOWERS AND THUNDERSTORMS TO DEVELOP AHEAD OF THE FRONT ON FRIDAY. HAVE CONTINUED THE TREND OF INCREASING RAIN CHANCES AND INTRODUCED LIKELY POPS FOR FRIDAY AFTERNOON DUE TO GOOD MODEL AGREEMENT ON WIDESPREAD COVERAGE. BETTER RAIN CHANCES WILL SHIFT SOUTHWARD INTO THE COASTAL COUNTIES AND OFFSHORE WATERS ON SATURDAY AS THE FRONTAL BOUNDARY REACHES THE COAST. THE UPPER RIDGE WILL REESTABLISH ITSELF ACROSS THE STATE BY EARLY NEXT WEEK ALLOWING TEMPERATURES TO WARM BACK INTO THE MID 90S. 38 MARINE... MODERATE EAST WINDS AND ELEVATED SEAS ARE EXPECTED TO PERSIST THROUGH MID WEEK. A STORM SYSTEM WILL MOVE ACROSS THE SOUTHERN PLAINS ON FRIDAY...AND THIS SYSTEM WILL DRAG A COLD FRONT ACROSS THE COASTAL WATERS LATE ON FRIDAY OR EARLY ON SATURDAY. A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THE FRONTAL BOUNDARY. 42 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 96 75 96 75 93 / 20 10 20 10 40 HOUSTON (IAH) 94 76 94 76 91 / 20 10 20 20 40 GALVESTON (GLS) 90 81 90 81 89 / 20 20 40 20 40 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 5 PM CDT THIS AFTERNOON FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$ DISCUSSION...31 AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1113 PM CDT MON SEP 16 2013 .DISCUSSION... See aviation discussion below... && .AVIATION... Showers continue near KBBD, and these may persist into the early morning hours, which is reflected in TAF package. Isolated showers or thunderstorms will be possible elsewhere overnight, but coverage should remain isolated enough to preclude a mention in the TAFs. Patchy stratus may develop at KJCT and KSOA around daybreak, but at this time I think ceilings will remain VFR. Otherwise, VFR conditions are expected to prevail with light winds. && .PREV DISCUSSION... /ISSUED 942 PM CDT MON SEP 16 2013/ UPDATE... Increased POPS sightly across southern sections overnight. DISCUSSION... Convection has diminished considerably across the Big Country this evening with only some light showers remaining. Meanwhile, a new area of showers and a few thunderstorms are developing across southeast counties with additional development farther southeast across the Hill Country. Most of the models are of little help this evening but the RUC does show an increase in activity along the I-10 corridor by early morning. Given the latest convective trends, have increased POPS to 40 percent across the south and will maintain 20 to 30 percent elsewhere for the overnight period. The rest of the forecast looks on track with no other changes needed at this time. PREV DISCUSSION... /ISSUED 613 PM CDT MON SEP 16 2013/ DISCUSSION... See aviation discussion below... AVIATION... Scattered showers and thunderstorms have decreased across much of West Central Texas during the last hour or so. I still expect isolated showers and thunderstorms through at least 02z, and this is reflected in the TAFs. A couple of outflow boundaries are moving toward KSJT, and this could result in brief gusty variable winds. Isolated to scattered showers and thunderstorms will be possible on Tuesday, but I have left any mention out of the TAF package due to low confidence. Overall, expect VFR conditions to prevail through the next 24 hours. PREV DISCUSSION... /ISSUED 409 PM CDT MON SEP 16 2013/ SHORT TERM... (Tonight and Tuesday) Upper level high pressure is currently resting across much of Texas and east into the Gulf of Mexico. This high pressure will be fixed through Tuesday evening, setting up south southeasterly flow across the area. This will assist in funneling moisture from Tropical Storm Ingrid and the remnants of Manuel into West Central Texas. With this flow pattern we expect the best chances of rainfall across our southwestern counties. We expect theses showers and thunderstorms to be diurnally driven, given the lack of capping and upper level support. Adjusted the overnight lows into the upper 60s and near 70 to account for the influx of moisture and expected cloud cover. Afternoon highs will be near normal with temperatures in the upper 80s to near 90. 18 LONG TERM... (Tuesday Night through Monday) Rain Chances Increase with Locally Heavy Rainfall Possible... The main forecast focus revolves around rain chances Wednesday- Friday, and the possibility of locally heavy rainfall. There is also potential for greater coverage of rainfall across our area. The upper high will shift a bit east and by Wednesday become centered over the northern Gulf of Mexico. Our area will be on its western periphery. The 12Z GFS and ECMWF show an upper reflection from the remnants of Ingrid moving north out of Mexico and into West Texas on Wednesday, followed by another upper level disturbance (possible remnants of tropical system near the western coast of Mexico) moving north- northeast into West Central Texas by Thursday morning. We have low POPs at this time Wednesday and Wednesday night, increasing Thursday. These may need to be raised substantially if subsequent model runs remain consistent. Locally heavy rainfall will be possible, with precipitable water values increasing to between 1.5 and 2 inches. On Friday, an upper trough moving into the Midwest will send a cold front south into Texas, with the front progged to sag south into West Central Texas. With a moist airmass remaining in place, could have additional showers and thunderstorms across our area. Carrying chance POPs Friday and these also may need to be increased. Drier conditions are indicated for our area next weekend with upper shortwave ridge building back into Texas. 19 && .PRELIMINARY POINT TEMPS/POPS... Abilene 71 89 70 92 71 / 20 20 10 10 10 San Angelo 70 88 69 92 71 / 30 30 10 10 20 Junction 70 87 69 91 70 / 40 30 10 10 20 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ Daniels
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
940 PM CDT WED SEP 18 2013 .UPDATE... AS THE UPPER TROUGH OVER THE NRN ROCKIES MOVES INTO THE HIGH PLAINS TNT...THE NOSE OF THE LOW LEVEL JET WILL REFOCUS OVER NE IA INTO SRN WI THROUGH THU AM. THE 00Z DVN SOUNDING IS VERY MOIST AND CONDITIONALLY UNSTABLE WITH PWS AT 1.77 INCHES AND ELEVATED CAPE OF 1561 J/KG WHEN LIFTING A PARCEL FROM 850 MB. NAM FORECAST SOUNDINGS SHOW SIMILAR THERMODYNAMICS ACROSS SRN WI. THUS NOT SURPRISED TO SEE THE HRRR MODEL INITIATING A GOOD AMOUNT OF CONVECTION AFTER 08Z OR 09Z OVER SOUTH CENTRAL WI AND REACHING SE WI BY SUNRISE. SOME TSTORMS TO BE STRONG WITH HEAVY RAINFALL. THUNDERSTORMS TO THEN DECREASE IN COVERAGE LATER IN THE MORNING OR EARLY AFTERNOON THEN INCREASE IN COVERAGE WITH THE COLD FROPA THU NT. CAPES WILL MAXIMIZE OVER 2000 J/KG THU AFTERNOON WITH 0-3 KM SRH FROM 150-200 M2/S2 AHEAD OF THE FRONT. DEEP LAYER SHEAR IS ONLY 20 KTS BUT JUST ENOUGH FOR ORGANIZED SVR STORMS WITH SOME POTENTIAL FOR SUPERCELLS GIVEN THE AFOREMENTIONED SRH. HEAVY RAINFALL EXPECTED WITH ANY STORMS GIVEN PWS UP TO 1.8 INCHES. STORM MOTION AROUND 30 KTS WILL LIMIT FLASH FLOOD POTENTIAL WITH THE EXCEPTION OF POSSIBLY A HIGH PCPN SUPERCELL. && .AVIATION/06Z TAFS/... MAINLY VFR CONDITIONS EARLY THU AM BUT SCATTERED TO NUMEROUS TSTORMS TO DEVELOP AFTER 09Z FOR KMSN AND AFTER 11Z FOR THE SE WI TAF SITES VIA A LOW LEVEL JET STREAM. TSTORMS TO LAST THROUGH THE MORNING BEFORE EXITING THE AREA. SOME MVFR CIGS AND VSBYS ARE POSSIBLE DURING OR AFTER THE TSTORMS BUT SHOULD RETURN TO VFR FOR THE AFTERNOON. WIDESPREAD TSTORMS THEN EXPECTED LATE THU AFTERNOON AND EVENING FOR KMSN AND THU NT FOR THE SE WI TAF SITES WITH A COLD FROPA. REDUCED CIGS AND VSBYS WITHIN STORMS AND MVFR CIGS AND VSBYS COULD LINGER AFTER THE STORMS...BUT SHOULD BE BRIEF DUE TO COLD AND DRY AIR ADVECTION AFTER COLD FROPA. && .PREV DISCUSSION... /ISSUED 342 PM CDT WED SEP 18 2013/ TONIGHT AND THURSDAY...FORECAST CONFIDENCE MEDIUM. SURFACE LOW PRESSURE STRENGTHENING OVER THE DAKOTAS IN RESPONSE TO A DIGGING UPPER TROUGH WILL TRACK INTO MN OVERNIGHT INTO THURSDAY. MOISTURE AND WARM AIR WILL CONTINUE TO STREAM NORTHWARD INTO WISCONSIN AHEAD OF THIS SYSTEM. WITH THESE CONDITIONS OVER SOUTHERN WI...ANY LITTLE SHORTWAVE COULD KICK UP SOME SCATTERED SHOWERS ANYWHERE IN SOUTHERN WI. THERE IS UPPER LEVEL INSTABILITY WITH 1000 J/KG OF CAPE TO SUPPORT ISOLATED THUNDER AS WELL. THERE IS A WEAK SHORTWAVE MOVING ACROSS SOUTHERN WI LATE THIS AFTERNOON...BUT THE ONLY SHOWERS AS A RESULT OCCURRED IN FAR SOUTHWEST WI AND ARE WEAKENING. THERE IS ALSO AN MCV MOVING THROUGH NORTHERN IL WHERE JUST SOME SPRINKLES ARE LEFT TO BRUSH FAR SOUTHERN WI LATE THIS AFTERNOON. EXPECTING LULL IN PRECIP CHANCES WITH THE LACK OF SHORTWAVES BETWEEN 00Z AND 06Z. THEN THE LOW LEVEL JET WILL BEGIN TO STRENGTHEN AND NOSE INTO IOWA AFTER 06Z. THE 18Z NAM AND 00Z ECMWF SHOW A WEAK SHORTWAVE MOVING INTO SOUTHERN WI LATE TONIGHT. THIS SHOULD RESULT IN A ROUND OF SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS LATE TONIGHT THROUGH 12Z THU...TAPERING OFF SOUTHWEST TO NORTHEAST THROUGH MID THU MORNING. THE ECMWF HINTS AT ANOTHER BULLSEYE OF QPF OVER SOUTH CENTRAL WI THU MORNING...POSSIBLY FROM AN MCV MOVING NORTHEAST FROM IOWA. THURSDAY AFTERNOON...CAPE INCREASES TO OVER 2000 J/KG IN SOUTH CENTRAL WI AND THERE SHOULD BE ENOUGH HEATING AND HIGH DEW POINTS TO OVERCOME A WEAK CAP AROUND 850MB. WHILE THESE CONDITIONS ARE RIGHT FOR FUELING SOME STRONGER THUNDERSTORMS...THERE IS STILL A LACK OF A GOOD TRIGGER AND ALSO SHEAR. HELD POPS IN THE 20 TO 30 PERCENT RANGE UNTIL LATER IN THE AFTERNOON WHEN A SHORTWAVE OUT AHEAD OF THE MAIN UPPER TROUGH APPROACHES. HEAVY RAIN WILL BE POSSIBLE IN ANY OF THOSE AFTERNOON THUNDERSTORMS...AS WELL AS VERY ISOLATED LARGE HAIL AND DAMAGING WIND. SHORT TERM...HURSDAY NIGHT THROUGH SATURDAY. THURSDAY NIGHT AND FRIDAY...FORECAST CONFIDENCE MEDIUM TO HIGH RAISED POPS TO CATEGORICAL FOR THURSDAY EVENING. MIXED LAYER CAPE VALUES OF 1500-2000 J/KG THURSDAY EVENING. 0-6KM BULK SHEAR IS 20 KNOTS OR LESS OVER EASTERN CWA...WITH SHEAR VALUES RISING TO AROUND 25 KNOTS IN THE WEST...ENOUGH FOR SOME MULTI-CELL CLUSTERS WITH STRONG WIND GUST POTENTIAL PER INVERTED V ON MODEL SOUNDINGS. SEVERE POTENTIAL DROPS OFF INTO THE MID-LATE EVENING AS CONVECTION BECOMES MORE ELEVATED. HOWEVER PW/S RISE TO BETWEEN 1.70-1.90 INCH...OR 200-220 PCT OF NORMAL...BY THURSDAY EVENING AND DO NOT BEGIN TO DROP OFF UNTIL AFTER 06Z FRIDAY. WITH SLOW EASTWARD PROGRESS OF 500 MB TROUGH AS VORTICITY MAXIMA DEEPEN THE TROUGH...WHICH ALSO SLOWS DEEPENING SURFACE LOW MOVING ACROSS SOUTHERN ONTARIO AND PROGRESS OF TRAILING COLD FRONT THROUGH REGION...POTENTIAL IS THERE FOR SOME HIGH EVENT RAIN TOTALS. WHILE SHOWERS AND STORMS WILL REPEATEDLY DEVELOP WITH PERSISTENT CONVERGENCE ALONG FRONT...IT WILL BE MOVING WITH INDIVIDUAL CELLS MOVING AT 10 KNOTS. FLASH FLOOD GUIDANCE IS BETWEEN 2 AND 4 INCHES AND LOCAL FLASH FLOOD CHECK LIST RESULT IS MARGINAL SO NO WATCH ANTICIPATED...BUT SOME LOCALIZED PONDING IS POSSIBLE. WILL TAPER OFF POPS FROM LIKELY IN THE EAST AND CHANCE WEST FRIDAY MORNING AS 850 AND 500 MB TROUGH AXES PUSH THROUGH AND EXIT THE REGION BETWEEN 18Z AND 00Z FRIDAY. LOWS WILL NOT DROP BELOW LOW TO MID 60S THURSDAY NIGHT...WITH LOW TO MID 70 HIGHS AROUND MIDDAY THEN STEADY OR SLOWLY COOLING WITH COOL AIR ADVECTION BEHIND FRONT. FRIDAY NIGHT AND SATURDAY...FORECAST CONFIDENCE HIGH COOL NIGHT FRIDAY NIGHT WITH HIGH PRESSURE AND 850 MB COLD POCKET SETTLING INTO REGION. ENOUGH MIXING TO PREVENT FULL RADIATIONAL COOLING BUT LOWS IN THE 40S EXPECTED AWAY FROM THE LAKE. EXPECT A BIT OF A SUPER ADIABATIC BUMP FOR SFC HIGHS TOP REACH MID TO UPPER 60S SATURDAY. LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY. FORECAST CONFIDENCE MEDIUM TO HIGH RIDGING BRINGS DRY CONDITIONS WITH SLOWLY WARMING TEMPERATURES SUNDAY THROUGH MONDAY. ENERGY FROM SHORT WAVE TROUGH EMERGING OUT INTO THE PLAINS SUNDAY NIGHT AND MONDAY LIFTS NE...WITH PRECIPITATION DISSIPATING ALONG WEAKENING SURFACE TROUGH AS IT RUNS INTO HIGH. LATER SHIFTS MAY BE ABLE TO COMPLETELY REMOVE SLIGHT CHANCE POPS FOR MONDAY NIGHT IF DRY TREND CONTINUES IN LATER RUNS. PRECIPITATION CHANCES FOR THE REMAINDER OF THE EXTENDED REMAIN WELL WEST WITH LEE TROUGH OVER THE PLAINS. AVIATION/00Z TAFS/... LOOKING FOR POTENTIAL MVFR CIGS AND VSBYS LATE TONIGHT DUE TO DEEPER MOISTURE STREAMING INTO SOUTHERN WI...ALONG WITH THE CHANCE FOR SCATTERED SHOWERS AND A FEW THUNDERSTORMS. CONFIDENCE NOT HIGH GIVEN THE HIGHER WINDS AND POSSIBLE LOW LEVEL MIXING THAT COULD INHIBIT THE LIGHT FOG AND LOWER CEILINGS. A PERIOD OF LOW LEVEL WIND SHEAR IS EXPECTED TONIGHT AS THE LOW LEVEL JET STRENGTHENS OVER THE REGION. THE BETTER CHANCE FOR STRONG THUNDERSTORMS WITH HEAVY RAIN WILL BE LATE THURSDAY AFTERNOON AND ALL OF THURSDAY NIGHT AS A COLD FRONT SLOWLY MOVES WEST TO EAST THROUGH THE UPPER MIDWEST. MARINE... A TIGHT PRESSURE GRADIENT OVER LAKE MICHIGAN IN RESPONSE TO LOW PRESSURE MOVING INTO THE NORTHERN PLAINS WILL CONTINUE TO BRING GUSTY SOUTH TO SOUTHEAST WINDS...WITH A PROLONGED PERIOD OF 10 TO 20 KNOT WINDS THROUGH THURSDAY AFTERNOON. A FEW WIND GUSTS LIKELY 22-25 KNOTS DURING PEAK HEATING TIMES. BETTER CHANCE FOR HIGHER WINDS AND RESULTANT WAVES NORTH OF PORT WASHINGTON DUE TO SHORE ORIENTATION. EXPECTING WAVES TO BUILD TO OVER 4 FEET AT TIMES. HENCE SMALL CRAFT ADVY IN EFFECT FOR THIS AREA INTO THURSDAY EVENING. AREAS FARTHER SOUTH WILL NEED TO BE WATCHED CLOSELY BUT NOT ENOUGH CONFIDENCE IN A PROLONGED PERIOD OF HIGHER WINDS AND WAVES AT THIS TIME. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THURSDAY FOR LMZ643. && $$ UPDATE...GEHRING TONIGHT/THURSDAY AND AVIATION/MARINE...MRC THURSDAY NIGHT THROUGH WEDNESDAY...REM
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1139 AM CDT TUE SEP 17 2013 .UPDATE... LOW LEVEL CLOUDS CONFINED TO THE LAKE RAPIDLY EXPANDED INLAND AS THE SURFACE INVERSION MIXED OUT. THIS IS BEING FED BY SOUTHEAST WINDS BRINGING LOW LEVEL MOISTURE INTO EASTERN WI. MADISON WILL EVEN SEE HINTS OF THESE LOW CLOUDS. EXPECTING THESE CLOUDS TO GRADUALLY SCATTER OUT DURING THE EARLY AFTERNOON. MEANWHILE...HIGH CLOUDS WILL CONTINUE TO EXPAND EASTWARD AHEAD OF AN APPROACHING POTENT SHORTWAVE MOVING THROUGH IOWA THIS MORNING. A PLUME OF HIGH PRECIPITABLE WATER ACCOMPANIES THIS SHORTWAVE TO PRODUCE SHOWERS. HRRR BRINGS THE SHOWERS CURRENTLY IN NORTHEAST IOWA INTO WEST CENTRAL WI AND AVOIDS THE MKX FORECAST AREA. WILL ACCOUNT FOR A SMALLER AREA OF SHOWERS CURRENTLY IN EASTERN IOWA THAT COULD SWING UP INTO SOUTH CENTRAL WI LATE THIS AFTERNOON BY INCREASING THE FORECAST CHANCE POPS A LITTLE EARLIER. && .AVIATION/18Z TAFS/... MVFR CLOUDS CONFINED TO THE LAKE RAPIDLY EXPANDED INLAND AS THE SURFACE INVERSION MIXED OUT. THIS IS BEING FED BY SOUTHEAST WINDS BRINGING LOW LEVEL MOISTURE INTO EASTERN WI. MADISON WILL EVEN SEE HINTS OF THESE LOW CLOUDS. EXPECTING THESE CLOUDS TO GRADUALLY SCATTER OUT DURING THE EARLY AFTERNOON. THEN EXPECT A VFR PERIOD WITH SCT-NMRS -SHRA SPREADING INTO SRN WI FROM LATE AFTN THRU TNGT. SMALL THREAT FOR T OVER S CENTRAL WI LATER TNGT INTO WEDNESDAY MORNING. && .PREV DISCUSSION... /ISSUED 330 AM CDT TUE SEP 17 2013/ TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM AREAS OF STRATUS WHICH DEVELOPED OVER THE LAKESHORE COUNTIES AROUND 06Z DUE TO LINGERING HIGH DELTA-T AND INCREASED LOW LEVEL CONVERGENCE HAVE BECOME MORE PATCHY IN LAST SEVERAL HOURS. LOW LEVEL WINDS WL CONTINUE TO VEER TO THE SSE THROUGH EARLY MORNING. WITH DELTA-T REMAINING AROUND 10C...PATCHY STRATUS MAY CONTINUE INTO THE MORNING AS HIGH CLOUDS INCREASE ACROSS THE AREA. WATER VAPOR IMAGERY AND WIND PROFILERS INDICATING STRONGER MID-LEVEL SHORT WAVE VCNTY OF KOMA THAN DEPICTED BY SHORT TERM GUIDANCE. HIGH PRECIPITABLE WATER VALUES ASSOCIATED WITH THIS WAVE. CURRENTLY AROUND 0.4 INCHES IN SRN WI. PWAT VALUES TRIPLE RAPIDLY TO AROUND 1.5 INCHES OVER NORTHWEST MO AND WRN IA PER GOES SOUNDER. THIS DEEPER MOISTURE AND SHORT WAVE MOVES OUR WAY TODAY INTO WRN CWA BY LATE AFTN AND ACROSS SRN WI TNGT. 305 THETA SURFACE AND LOWER CONDENSATION PRESSURE DEFICITS LINE UP WELL WITH ONGOING -SHRA OVER WRN IA. THESE LOWER VALUES SPREAD INTO SOUTHWEST WI LATE AFTN AS SHORT WAVE MOVES INTO THE AREA. HENCE ADDED SOME POPS TO WRN CWA LATER TODAY AND BEEFED UP POPS SLIGHTLY THIS EVENING AS MOISTURE AND FORCING ASSOCD WITH SHORT WAVE SPREAD ACROSS THE AREA. BETTER CHANCE FOR NMRS -SHRA AND ISOLD T LATER TONIGHT AS DEEPER MOISTURE SETTLES INTO SRN WI AND WEAK LOW LEVEL JET PIVOTS INTO THE AREA. WITH STRONG UPSTREAM MOISTURE ADVECTION...THINKING PARTLY SUNNY SKIES AT BEST TODAY...WITH SOME AREAS LIKELY TURNING MOSTLY CLOUDY. CLOUDS WILL RETARD HIGH TEMPS A FEW DEGREES...ESPECIALLY WITH SE SFC WINDS. WEDNESDAY THROUGH FRIDAY...FORECAST CONFIDENCE...MEDIUM LOOKS LIKE PRETTY DEEP MOISTURE WEDNESDAY...WITH PRECIPITABLE WATER VALUES UP TO AROUND 1.75 INCHES. DO THINK THERE WILL BE SOME ACTIVITY WITH DECENT LOW LEVEL FLOW...WEAK WARM ADVECTION...AND SOME ELEVATED INSTABILITY. SOUNDINGS LOOK SOMEWHAT CAPPED FOR PART OF THE DAY AND NOT SEEING A REAL GOOD TRIGGER...SO WENT WITH CHANCE POPS...NOT DEVIATING MUCH FROM THE PREVIOUS FORECAST. A LOT OF CLOUDS EXPECTED WEDNESDAY...WITH MODELS STRUGGLING TO MIX TO EVEN 925 MB. THUS KEPT TEMPS A BIT CLOSER TO 2 METER MODEL VALUES...THOUGH HIGHS WILL STILL BE NEAR TO A COUPLE DEGREES ABOVE NORMAL. STRONGEST LOW LEVEL WINDS WILL BE TO THE SOUTHWEST WEDNESDAY NIGHT...BUT 30-40 KNOT JET DOES POINT INTO THE FORECAST AREA. STILL WILL BE A GOOD AMOUNT OF MOISTURE WITH INCREASING ELEVATED INSTABILITY...GETTING AS HIGH AS 1500 J/KG ON NAM SOUNDINGS. WOULD NOT TAKE MUCH TO KICK OFF MORE SHOWERS/STORMS...SO KEPT CHANCE POPS GOING. INSTABILITY IS EXPECTED TO INCREASE EVEN MORE THURSDAY AS A WARM AND MOIST AIRMASS IS PULLED INTO THE AREA AHEAD OF AN APPROACHING COLD FRONT. PRECIP CHANCES ARE EXPECTED TO INCREASE AS THE FRONT DRAWS NEAR...SO WENT WITH LIKELY POPS MAINLY WEST OF MADISON DURING THE DAY AND THEN ACROSS THE FORECAST AREA IN THE EVENING/OVERNIGHT AS THE FRONT DRAWS CLOSER OR MOVES THROUGH. LOOKS LIKE A BETTER CHANCE FOR SOME SUNSHINE AND DEEPER MIXING THAN ON WEDNESDAY. THE AIRMASS ALOFT WILL BE MILDER AS WELL...SO EXPECTING A WARM DAY INTO THE LOW 80S MOST PLACES. BUMPED POPS UP A BIT FRIDAY...AS MAIN SHORTWAVE WILL BE MOVING THROUGH. MODELS HAVE THE SURFACE FRONT RANGING FROM JUST MOVING INTO THE FORECAST AREA TO JUST THROUGH BY DAYBREAK. STILL A GOOD AMOUNT OF MOISTURE AND WARM AIR ALOFT AHEAD OF THE SHORTWAVE THOUGH...SO LOOKS LIKE A DECENT CHANCE FOR LINGERING SHOWERS/STORMS DURING THE MORNING...MAYBE EVEN HANGING ON IN THE EAST INTO THE AFTERNOON PER THE SLOWER MODEL SOLUTIONS. COOLER TEMPS ARE LIKELY FRIDAY...THOUGH HIGHS ARE STILL EXPECTED TO BE NEAR NORMAL VALUES. SATURDAY THROUGH MONDAY...FORECAST CONFIDENCE...MEDIUM AFTER A VERY ACTIVE PERIOD...HIGH PRESSURE IS EXPECTED TO SETTLE IN FOR THE WEEKEND...HANGING ON INTO EARLY NEXT WEEK. SHOULD THUS SEE A GOOD AMOUNT OF SUNSHINE SATURDAY THROUGH MONDAY WITH SLOWLY WARMING TEMPERATURES. MAIN ISSUE IS HOW QUICKLY TO WARM THINGS BACK UP...AS THE GFS KEEPS TEMPS QUITE A BIT COOLER THAN THE ECMWF AND CANADIAN. GENERALLY SPLIT THE DIFFERENCE IN TEMPS FOR NOW. EITHER WAY...LOOKS LIKE A PLEASANT STRETCH OF WEATHER. AVIATION/12Z TAFS/...AREAS OF STRATUS WHICH DEVELOPED OVER THE LAKESHORE COUNTIES AROUND 05-06Z DUE TO HIGHER DELTA-T AND INCREASED LOW LEVEL CONVERGENCE HAVE BECOME MORE PATCHY IN LAST HOUR OR SO. WOULD THINK THIS WILL CONTINUE AS LOW LEVEL WINDS CONTINUE TO VEER TO THE SSE EARLY THIS MRNG. HOWEVER DELTA-T REMAINS AROUND 10C THROUGH THE EARLY MORNING SO THREAT FOR LOW CLOUDS WL CONTINUE THROUGH 15Z OR SO. OTRW EXPECT A VFR PERIOD WITH SCT-NMRS -SHRA SPREADING INTO SRN WI FROM LATE AFTN THRU TNGT. SMALL THREAT FOR T OVER S CENTRAL WI LATER TNGT. MARINE...PRESSURE GRADIENT TIGHTENS OVER LAKE MICHIGAN TODAY AS HIGH PRESSURE MOVES OFF TO THE EAST AND LOW PRESSURE DEVELOPS IN THE HIGH PLAINS. WIND SPEEDS WILL INCREASE TO 10 TO 20 KNOTS TODAY AND PERSIST UNTIL COLD FRONT MOVES THROUGH FRIDAY MORNING. FEW GUSTS MAY REACH SMALL CRAFT ADVISORY LEVELS DURING THIS TIME BUT NO PROLONGED PERIOD OF HIGHER GUSTS EXPECTED. WAVES WILL INCREASE TO 2 TO 4 FEET FOR MUCH OF THE PERIOD AS WELL. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ UPDATE...MRC TODAY/TONIGHT AND AVIATION/MARINE...MBK WEDNESDAY THROUGH MONDAY...DDV
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
313 AM MDT THU SEP 19 2013 .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 310 AM MDT THU SEP 19 2013 COLD FRONT IS NOW LOCATED ALONG I-70 AND IS EXPECTED TO CONTINUE DROPPING SEWRD TO NEAR THE SAN JUAN MOUNTAINS BEFORE WASHING OUT. THE UPPER LEVEL TROUGH IS LAGGING BEHIND THE SFC FRONT AND IS JUST ENTERING WRN CO AT THIS HOUR. AHEAD OF THE TROUGH...RADAR PICKING UP SOME RETURNS N OF I-70 WITH A FEW STRAY STORMS ALSO FORMING THANKS TO UPPER LEVEL SUPPORT AND OROGRAPHIC LIFT. EXPECT THIS TO CONTINUE THROUGH DAYBREAK WITH SOME MIDLEVEL CLOUDS AROUND THE AREA FOR THE COMMUTE TO WORK. 00Z NAM12 SHOWED SOME VERY ISOLD SHOWERS OVER CENT/SRN MTNS THIS AFTERNOON DUE TO LIMITED MOISTURE AND SOME OROGRAPHICS WHILE 06Z NAM12 HAS ALL BUT REMOVED THEM. LATEST HRRR AND RAP13 GUIDANCE ALSO SHOWING A DISTINCT LACK OF PRECIP FOR THE ENTIRE CWA TODAY. NOT SOLD ON IDEA THOUGH AS SOME MARGINAL INSTABILITY EXISTS ALONG WITH SOME MOISTURE IN LOWER LEVELS. FOR NOW...WILL LEAVE ISOLD CONVECTION IN FORECAST FOR THE HIGHEST TERRAIN IN THE SAN JUANS AND CENTRAL MTNS. MOST AREAS TODAY WILL SEE SUN...SUN...AND MORE SUN AND MORE FALL LIKE TEMPERATURES AS A PATTERN SHIFT FINALLY SETS UP. ANY LINGERING SHOWER OR STORM NEAR THE CENTRAL OR SOUTHERN DIVIDE WILL QUICKLY DIMINISH THIS EVENING WITH SUNSET. WEAK WARM ADVECTION ALOFT THEN COMMENCES TONIGHT AS A PROGRESSIVE UPPER RIDGE APPROACHES...BUT IT WILL NOT LIKELY BE ENOUGH TO OFFSET RADIATIONAL COOLING DUE TO CLEAR SKIES AND DRIER AIR. HENCE...A COOL NIGHT LOOKS IN STORE WITH POCKETS OF FREEZING OR NEAR FREEZING TEMPS TO THE LOWER VALLEYS IN THE CRAIG AND MEEKER AREAS AND WILL CONTINUE THE FREEZE WATCH FOR THESE AREAS TONIGHT. MODELS SUGGEST THAT THE STEAMBOAT VALLEY AND AROUND GUNNISON WILL BOTTOM OUT IN THE MID 30S. TEMPS SHOULD WARM QUICKLY FRIDAY MORNING WITH PLENTY OF SUNSHINE. DRY AND SUNNY CONDITIONS ARE EXPECTED FRIDAY WITH HIGH TEMPS REBOUNDING AS THE UPPER RIDGE SLIDES ACROSS THE AREA. AFTERNOON HUMIDITIES WILL DROP INTO THE TEENS FRIDAY AFTERNOON IN MANY OF THE NORTHWEST AND WEST-CENTRAL COLORADO VALLEYS...AND EASTERN UTAH VALLEYS. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 310 AM MDT THU SEP 19 2013 FLOW ALOFT BECOMES SOUTHWEST FRIDAY NIGHT AND SATURDAY AS THE UPPER RIDGE MOVES TO THE EAST AND A PACIFIC TROUGH PUSHES INLAND. GRADIENT TIGHTENS SATURDAY AS THE TROUGH ADVANCES FOR STRENGTHENING AND GUSTY SURFACE WINDS ACROSS NE UT/NW CO SATURDAY AFTERNOON...AND TEMPS SHOULD WARM OVER FRIDAY. NAM MODEL SHOWS MID-LEVEL MOISTURE BEING DRAWN NORTHWARD INTO SW CO AS EARLY AS FRI NIGHT WHILE THE GFS WAITS UNTIL SAT. THE EVENING MODELS ALSO DID SEEM QUITE AS ENTHUSIASTIC WITH RAISING PRECIPITABLE WATER VALUES AS EARLIER RUNS. STILL...MAY SEE A FEW SHOWERS OR THUNDERSTORMS OVER THE SAN JUANS SAT AFTERNOON AND MADE LITTLE CHANGE TO THE CURRENT FORECAST FOR THE FIRST HALF OF THE WEEKEND. BIG DIFFERENCE IN LONG-TERM FOR THE WEEKEND AS PREVIOUS GFS RUNS SHOWED MARGINAL PRECIP WITH AN APPROACHING TROUGH AND SFC COLD FRONT WHILE LATEST RUN SHOWS SIGNIFICANT PRECIP FOR MUCH OF THE AREA SUNDAY AFTERNOON AND NIGHT. EC ALSO SHOWING THIS PRECIP WHILE NAM12 SHOWING VERY LITTLE AT THIS TIME. MOISTURE TRANSPORT VECTORS ON THE 320K SURFACE DO SHOW SOME MOISTURE STREAMING UP FROM THE SOUTH SATURDAY NIGHT INTO SUNDAY MORNING BEFORE BEING WORKED ON BY THE TROUGH. THE TROUGH WILL BE SUPPORTED BY AN 80 KT JET STREAK AND IT LOOKS LIKE THIS TROUGH MAY BECOME NEGATIVELY TILTED. IF YOU PUT ALL OF THESE TOGETHER...SOME WIDESPREAD PRECIP CAN BE EXPECTED WITH SOME STRONG THUNDERSTORMS POSSIBLE. CAN ALSO EXPECT SOME GUSTY SFC WINDS...ESPECIALLY SUNDAY...AHEAD OF SAID FRONT. SOME WHITE STUFF ALSO POSSIBLE AT THE HIGHEST ELEVATIONS...ABOVE 13K FT...AS H7 TEMPS DROP TO AROUND 3C. SFC TEMPERATURES WILL DROP 8 TO 10 DEGREES FROM SATURDAY TO SUNDAY AS THE COLD FRONT PUSHES THROUGH. BY MONDAY MORNING...THE TROUGH AND FRONT WILL HAVE EXITED OUR AREA ALLOWING ZONAL FLOW TO SET UP BRINGING A PERIOD OF DRY WEATHER AND SEASONAL TEMPERATURES THROUGH WEDNESDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 310 AM MDT THU SEP 19 2013 VFR CONDITIONS ARE PREDOMINANT AT THIS HOUR AND THESE CONDITIONS WILL CONTINUE FOR THE NEXT 24 HOURS. A SLIGHT CHANCE EXISTS FOR SOME CONVECTION TO FIRE OVER THE HIGHER ELEVATIONS OF THE SAN JUANS AND CENTRAL MOUNTAINS BUT NO EFFECTS TO TAF SITES EXPECTED. SOME MOUNTAIN OBSCURATIONS WILL CONTINUE THROUGH DAYBREAK TODAY. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...FREEZE WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING FOR COZ002. UT...NONE. && $$ SHORT TERM...TGR/JAD LONG TERM...JAD/TGR AVIATION...TGR
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
315 AM CDT THU SEP 19 2013 .DISCUSSION... 336 PM CDT MAIN CHALLENGES/CONCERNS THIS FORECAST PERIOD ARE WITH SHOWERS AND THUNDERSTORMS IN THE NEAR TERM...POSSIBLE PERSISTENT SHOWERS/THUNDERSTORMS OVERNIGHT...AS WELL AS BETTER CHANCES FOR SHOWERS/THUNDERSTORMS THURSDAY NIGHT INTO FRIDAY MORNING. CONTINUE TO MONITOR AREA OF SHOWERS AND THUNDERSTORMS ACROSS NORTH CENTRAL ILLINOIS THAT HAVE CONTINUED TO SLOWLY MOVE EAST TODAY. LATEST RADAR IMAGERY DEPICTING A CONTINUED DEVELOPING TREND IN BOTH COVERAGE AND INTENSITY WITH THIS AREA OF PRECIPITATION...AND EXPECT THIS TO CONTINUE THROUGH THE AFTERNOON AND EARLY EVENING. MCV IS THE MAIN DRIVING FORCE FOR THESE SHOWERS/THUNDERSTORMS...WITH LATEST RAP ANALYSIS SHOWING LOWERING CIN AND AN AXIS OF 1000 J/KG OF SB CAPE EXTENDING INTO NORTHEAST ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH NOT THE GREATEST...THESE CONDITIONS WILL BE ENOUGH TO HELP THIS PRECIP TO HOLD TOGETHER WHILE IT SLOWLY MOVES THROUGH NORTHEAST ILLINOIS THIS AFTERNOON AND THEN NORTHWEST INDIANA THROUGH EARLY EVENING. ALTHOUGH WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED...A PORTION OF THESE STORMS ALONG THE I-80 CORRIDOR HAVE EXHIBITED SOME STRENGTHENING TRENDS WITH BRIEF HIGHER WIND SIGNATURES. SO FOR THIS AFTERNOON/EARLY EVENING...EXPECT ANY OF THE STRONGER STORMS IN THIS GENERAL AREA TO BE CAPABLE OF PRODUCING SPORADIC WIND GUSTS TO 50 MPH...CONTINUOUS LIGHTNING...AND BRIEF HEAVY RAINFALL WITH AN OUTSIDE POSSIBILITY OF AN ISOLATED SEVERE WIND THREAT. WITH THE DEPARTURE OF THESE THUNDERSTORMS...MOST OF THE CWA SHOULD OBSERVE A LULL IN PRECIP BEFORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ONCE AGAIN OVER NIGHT. SEVERAL WEAK MID LEVEL FEATURES WILL CONTINUE TO TRAVERSE CURRENT ZONAL FLOW OVERHEAD...WITH LOW/MID LEVEL FLOW VEERING OVERNIGHT. AS THIS OCCURS...IT APPEARS AS BETTER WAA WILL ORIENT ITSELF MORE TOWARDS NORTHERN ILLINOIS. ALTHOUGH CONFIDENCE IS NOT THE GREATEST FOR COVERAGE TONIGHT...DID MAINTAIN LOW CHANCE POPS FOR MOST AREAS MAINLY AFTER MIDNIGHT OWING TO THIS POTENTIAL. WHATEVER DOES DEVELOP SHOULD BE MORE SCATTERED IN NATURE...AND THEN BEGIN SHIFTING EAST OUT OF THE CWA WHILE DIMINISHING EARLY THURSDAY MORNING. WITH BROAD SOUTHWESTERLY FLOW PERSISTING ON THURSDAY AND A FAIRLY MOIST ENVIRONMENT OVERHEAD...SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE. ALTHOUGH...CHANCES FOR PRECIPITATION SHOULD REMAIN LOW WITH ONCE AGAIN ANYTHING THAT DOES DEVELOP REMAINING SCATTERED. WITH THIS PERSISTENT WAA...CONTINUED WARMUP WILL CONTINUE ON THURSDAY. MADE LITTLE ADJUSTMENTS TO MAX TEMPS FOR THURSDAY KEEPING UPPER 80S FOR MOST LOCATIONS...WITH SOME UNCERTAINTIES TO PRECIP AND EVEN CLOUD COVER REMAINING. IF ENOUGH CLEARING OCCURS...THERMO PROFILES WILL BE SUPPORTIVE OF SOME LOCATIONS REACHING OR SLIGHTLY EXCEEDING 90 DEGREES. MAIN FOCUS FOR THUNDERSTORM DEVELOPMENT SHIFTS TOWARDS THE LATE AFTERNOON AND EARLY EVENING WITH AN APPROACHING TROUGH OF LOW PRESSURE AND COLD FRONT. AS LARGE VORT MAX DROPS SOUTHEAST ACROSS THE NORTHERN PLAINS...SEVERAL WAVES OF ENERGY WILL LIFT NORTHEAST ACROSS THE REGION. THIS WILL HELP TO SHIFT THIS TROUGH/FRONT AS WELL AS INDUCING SOME FURTHER PRESSURE FALLS OUT AHEAD OF IT. WITH POTENTIAL FOR PRE FRONTAL TROUGHINESS TO OCCUR TOMORROW AFTERNOON...SOME GUIDANCE CONTINUES TO DEVELOP PRECIP OUT AHEAD OF THIS FRONT. ALTHOUGH I FEEL THIS IS A BIT OVERDONE...AND HAVE HELD BACK ON POPS FOR THURSDAY DURING THE DAY. HAVE EVEN TRENDED TOWARDS A SLOWER SOLUTION/TREND WITH THIS FRONT/TROUGH WITH BEST CHANCES FOR SHOWERS/THUNDERSTORMS REMAINING OVER WEST/NORTHWEST ILLINOIS FOR MOST OF THURSDAY NIGHT. ITS NOT UNTIL EARLY FRIDAY MORNING THAT THIS FRONT GETS A GOOD SOUTHEAST PUSH WITH BEST FORCING MOVING OVERHEAD. GOOD SWATH OF PRECIP SHOULD SHIFT SOUTHEAST ACROSS THE ENTIRE CWA THROUGH MID DAY FRIDAY...WITH THIS PRECIP THEN EXPECTED TO SHIFT OUT OF THE AREA THROUGH THE AFTERNOON. IT DOES APPEAR AS IF THE STRONGER STORMS SHOULD REMAIN JUST WEST OF THE CWA...BUT WITH SOME POTENTIAL FOR THEM TO REACH THE FAR WESTERN CWA THURSDAY EVENING/NIGHT. IF INSTABILITY CAN INCREASE ON FRIDAY...THERE IS THE POTENTIAL FOR A LINGERING STRONG TO SEVERE THREAT ACROSS THE CWA BEFORE THE STORMS SHIFT OUT OF THE CWA. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * LOW CHANCE FOR ADDITIONAL SHRA/TSRA DURG THE MORNING HOURS. * ANOTHER ROUND OF SHRA/TSRA POSSIBLE LATE THURSDAY NIGHT WITH COLD FRONT PASSAGE. * SLY TO SSWLY WINDS GUSTING TO ARND 20KT LATE MORNING THROUGH EARLY EVENING. KREIN //DISCUSSION...UPDATED 06Z... TWO PRIMARY CONCERNS THROUGH THE PERIOD WILL BE CHANCES FOR ADDITIONAL SHRA/TSRA AND SLY-SSWLY WINDS GUSTING IN THE LOW 20S KT. THE REGION REMAINS UNDER WARM/MOIST ADVECTION WITH SLY FLOW AT THE SFC AND SWLY FLOW THROUGH THE LOWEST 10KFT ABOVE THE SFC LAYER. WHILE THE STRONGEST WARM ADVECTION AND ISENTROPIC LIFT REMAINS TO THE WEST...OVER THE UPPER MISSOURI VALLEY TO THE MIDDLE MISSISSIPPI VALLEY...THERE WILL STILL BE ENOUGH FORCING TO KEEP A CHANCE OF SHRA/TSRA IN THE TAFS. CONFIDENCE IS LOW AS TO THE TIMING AND COVERAGE OF PCPN THIS MORNING...SO WILL KEEP THE TEMPO GROUP IN THE FORECAST. LATEST RADAR IMAGERY ONLY INDICATES SOME ISOLD ECHOES OVER NRN IL/IN...ASIDE FROM THE ONGOING CONVECTION OVER NWRN INDIANA...EAST OF GYY. BUT GIVEN THE MOIST ENVIRONMENT...WILL LEAVE THE TEMPO IN THE FORECAST FOR A LITTLE LONGER AS THERE IS A CHANCE FOR INCREASED DEVELOPMENT THROUGH THE MORNING HOURS. WHILE THERE MAY STILL BE LOW CHANCES FOR ADDITIONAL SHRA/TSRA THROUGH THE AFTERNOON AND INTO EARLY EVENING...CONFIDENCE IN TIMING AND COVERAGE IS EVEN LOWER...SO WILL KEEP THE FORECAST DRY THROUGH THIS EVENING. THE NEXT...MORE SIGNIFICANT CHANCE FOR SHRA/TSRA WILL COME OVERNIGHT THURSDAY NIGHT AS A STRONG COLD FRONT APPROACHES THE REGION. THE CONVECTIVE ACTIVITY SHOULD LARGELY BE INVOF THE FRONT...WHICH SHOULD MOVE INTO NWRN IL BY LATE THIS EVENING AND THEN REACH THE CHICAGO AREA TERMINALS. CONFIDENCE IS A LITTLE HIGHER WITH THIS SYSTEM...SO HAVE ADDED A TEMPO GROUP THE END OF THE RFD TAF...AND A PROB30 GROUP TO THE 30-HR EXTENDED PERIOD OF THE ORD TAF. AS TIMING OF THE FRONTAL PASSAGE BECOMES A BIT MORE CERTAIN...WILL LIKELY NEED TO CARRY A PREVAILING GROUP TSRA. FOR WINDS...THERE IS LITTLE CHANGE TO THE GOING FORECAST. WINDS SHOULD REMAIN SLY THROUGH THE NIGHT AT ARND 10KT. THERE IS A CHANCE FOR SOME HIGHER GUSTINESS IF ADDITIONAL PCPN DOES DEVELOP. WITH DAYTIME WARMING AND SOME BREAKING UP OF CLOUD COVER...HIGHER GUSTS SHOULD MIX DOWN TO THE SFC AND FREQUENT GUSTS TO ARND 20KT SHOULD PREVAIL FROM LATE MORNING THROUGH EARLY EVENING. AS THE FRONTAL TROUGH APPROACHES THE MISSISSIPPI RIVER LATER TODAY...WIND DIRECTION SHOULD VEER A LITTLE WEST OF SOUTH TO 200-210 DEGREES BEFORE QUICKLY SHIFTING TO NWLY WITH THE FROPA. //ORD AND MDW CONFIDENCE...UPDATED 06Z... * LOW CONFIDENCE ON SHRA/TSRA THROUGH LATE THIS MORNING. * MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS. * MEDIUM TO HIGH CONFIDENCE IN ADDITIONAL SHRA/TSRA LATE THURSDAY NIGHT INTO FRIDAY MORNING WITH THE FROPA...BUT LOWER CONFIDENCE IN EXACT TIMING. * HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. KREIN //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY IN THE AFTERNOON. SATURDAY THROUGH TUESDAY...VFR. WX NIL. KJB && .MARINE... 300 AM CDT AN AREA OF LOW PRESSURE CENTERED OVER THE EASTERN DAKOTAS WILL WEAKEN SLIGHTLY AND TRACK NORTHEAST TO WESTERN ONTARIO BY THIS EVENING. SOUTHERLY WINDS TO AROUND 25 KT WILL PERSIST OVER THE LAKE AS THE THE LOW DEEPEN FURTHER AND TRACKS NORTHEAST INTO NORTHERN QUEBEC BY SATURDAY MORNING. AN ASSOCIATED COLD FRONT WILL SWEEP ACROSS LAKE MICHIGAN FRIDAY AFTERNOON AND EVENING...WITH WINDS GRADUALLY VEERING FROM SOUTHWESTERLY TO NORTHWESTERLY AND...ULTIMATELY NORTHEASTERLY...AS A LARGE AREA OF HIGH PRESSURE BUILDS IN BEHIND THE FRONT. IN THE COLD ADVECTION BEHIND THE FRONT...NORTHWEST TO NORTH WINDS WILL REDEVELOP...WITH SOME OCCASIONAL GUSTS TO 30KT POSSIBLE FRIDAY NIGHT. KREIN && .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
1250 AM CDT THU SEP 19 2013 .DISCUSSION... 336 PM CDT MAIN CHALLENGES/CONCERNS THIS FORECAST PERIOD ARE WITH SHOWERS AND THUNDERSTORMS IN THE NEAR TERM...POSSIBLE PERSISTENT SHOWERS/THUNDERSTORMS OVERNIGHT...AS WELL AS BETTER CHANCES FOR SHOWERS/THUNDERSTORMS THURSDAY NIGHT INTO FRIDAY MORNING. CONTINUE TO MONITOR AREA OF SHOWERS AND THUNDERSTORMS ACROSS NORTH CENTRAL ILLINOIS THAT HAVE CONTINUED TO SLOWLY MOVE EAST TODAY. LATEST RADAR IMAGERY DEPICTING A CONTINUED DEVELOPING TREND IN BOTH COVERAGE AND INTENSITY WITH THIS AREA OF PRECIPITATION...AND EXPECT THIS TO CONTINUE THROUGH THE AFTERNOON AND EARLY EVENING. MCV IS THE MAIN DRIVING FORCE FOR THESE SHOWERS/THUNDERSTORMS...WITH LATEST RAP ANALYSIS SHOWING LOWERING CIN AND AN AXIS OF 1000 J/KG OF SB CAPE EXTENDING INTO NORTHEAST ILLINOIS AND NORTHWEST INDIANA. ALTHOUGH NOT THE GREATEST...THESE CONDITIONS WILL BE ENOUGH TO HELP THIS PRECIP TO HOLD TOGETHER WHILE IT SLOWLY MOVES THROUGH NORTHEAST ILLINOIS THIS AFTERNOON AND THEN NORTHWEST INDIANA THROUGH EARLY EVENING. ALTHOUGH WIDESPREAD SEVERE WEATHER IS NOT ANTICIPATED...A PORTION OF THESE STORMS ALONG THE I-80 CORRIDOR HAVE EXHIBITED SOME STRENGTHENING TRENDS WITH BRIEF HIGHER WIND SIGNATURES. SO FOR THIS AFTERNOON/EARLY EVENING...EXPECT ANY OF THE STRONGER STORMS IN THIS GENERAL AREA TO BE CAPABLE OF PRODUCING SPORADIC WIND GUSTS TO 50 MPH...CONTINUOUS LIGHTNING...AND BRIEF HEAVY RAINFALL WITH AN OUTSIDE POSSIBILITY OF AN ISOLATED SEVERE WIND THREAT. WITH THE DEPARTURE OF THESE THUNDERSTORMS...MOST OF THE CWA SHOULD OBSERVE A LULL IN PRECIP BEFORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ONCE AGAIN OVER NIGHT. SEVERAL WEAK MID LEVEL FEATURES WILL CONTINUE TO TRAVERSE CURRENT ZONAL FLOW OVERHEAD...WITH LOW/MID LEVEL FLOW VEERING OVERNIGHT. AS THIS OCCURS...IT APPEARS AS BETTER WAA WILL ORIENT ITSELF MORE TOWARDS NORTHERN ILLINOIS. ALTHOUGH CONFIDENCE IS NOT THE GREATEST FOR COVERAGE TONIGHT...DID MAINTAIN LOW CHANCE POPS FOR MOST AREAS MAINLY AFTER MIDNIGHT OWING TO THIS POTENTIAL. WHATEVER DOES DEVELOP SHOULD BE MORE SCATTERED IN NATURE...AND THEN BEGIN SHIFTING EAST OUT OF THE CWA WHILE DIMINISHING EARLY THURSDAY MORNING. WITH BROAD SOUTHWESTERLY FLOW PERSISTING ON THURSDAY AND A FAIRLY MOIST ENVIRONMENT OVERHEAD...SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE. ALTHOUGH...CHANCES FOR PRECIPITATION SHOULD REMAIN LOW WITH ONCE AGAIN ANYTHING THAT DOES DEVELOP REMAINING SCATTERED. WITH THIS PERSISTENT WAA...CONTINUED WARMUP WILL CONTINUE ON THURSDAY. MADE LITTLE ADJUSTMENTS TO MAX TEMPS FOR THURSDAY KEEPING UPPER 80S FOR MOST LOCATIONS...WITH SOME UNCERTAINTIES TO PRECIP AND EVEN CLOUD COVER REMAINING. IF ENOUGH CLEARING OCCURS...THERMO PROFILES WILL BE SUPPORTIVE OF SOME LOCATIONS REACHING OR SLIGHTLY EXCEEDING 90 DEGREES. MAIN FOCUS FOR THUNDERSTORM DEVELOPMENT SHIFTS TOWARDS THE LATE AFTERNOON AND EARLY EVENING WITH AN APPROACHING TROUGH OF LOW PRESSURE AND COLD FRONT. AS LARGE VORT MAX DROPS SOUTHEAST ACROSS THE NORTHERN PLAINS...SEVERAL WAVES OF ENERGY WILL LIFT NORTHEAST ACROSS THE REGION. THIS WILL HELP TO SHIFT THIS TROUGH/FRONT AS WELL AS INDUCING SOME FURTHER PRESSURE FALLS OUT AHEAD OF IT. WITH POTENTIAL FOR PRE FRONTAL TROUGHINESS TO OCCUR TOMORROW AFTERNOON...SOME GUIDANCE CONTINUES TO DEVELOP PRECIP OUT AHEAD OF THIS FRONT. ALTHOUGH I FEEL THIS IS A BIT OVERDONE...AND HAVE HELD BACK ON POPS FOR THURSDAY DURING THE DAY. HAVE EVEN TRENDED TOWARDS A SLOWER SOLUTION/TREND WITH THIS FRONT/TROUGH WITH BEST CHANCES FOR SHOWERS/THUNDERSTORMS REMAINING OVER WEST/NORTHWEST ILLINOIS FOR MOST OF THURSDAY NIGHT. ITS NOT UNTIL EARLY FRIDAY MORNING THAT THIS FRONT GETS A GOOD SOUTHEAST PUSH WITH BEST FORCING MOVING OVERHEAD. GOOD SWATH OF PRECIP SHOULD SHIFT SOUTHEAST ACROSS THE ENTIRE CWA THROUGH MID DAY FRIDAY...WITH THIS PRECIP THEN EXPECTED TO SHIFT OUT OF THE AREA THROUGH THE AFTERNOON. IT DOES APPEAR AS IF THE STRONGER STORMS SHOULD REMAIN JUST WEST OF THE CWA...BUT WITH SOME POTENTIAL FOR THEM TO REACH THE FAR WESTERN CWA THURSDAY EVENING/NIGHT. IF INSTABILITY CAN INCREASE ON FRIDAY...THERE IS THE POTENTIAL FOR A LINGERING STRONG TO SEVERE THREAT ACROSS THE CWA BEFORE THE STORMS SHIFT OUT OF THE CWA. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * LOW CHANCE FOR ADDITIONAL SHRA/TSRA DURG THE MORNING HOURS. * ANOTHER ROUND OF SHRA/TSRA POSSIBLE LATE THURSDAY NIGHT WITH COLD FRONT PASSAGE. * SLY TO SSWLY WINDS GUSTING TO ARND 20KT LATE MORNING THROUGH EARLY EVENING. KREIN //DISCUSSION...UPDATED 06Z... TWO PRIMARY CONCERNS THROUGH THE PERIOD WILL BE CHANCES FOR ADDITIONAL SHRA/TSRA AND SLY-SSWLY WINDS GUSTING IN THE LOW 20S KT. THE REGION REMAINS UNDER WARM/MOIST ADVECTION WITH SLY FLOW AT THE SFC AND SWLY FLOW THROUGH THE LOWEST 10KFT ABOVE THE SFC LAYER. WHILE THE STRONGEST WARM ADVECTION AND ISENTROPIC LIFT REMAINS TO THE WEST...OVER THE UPPER MISSOURI VALLEY TO THE MIDDLE MISSISSIPPI VALLEY...THERE WILL STILL BE ENOUGH FORCING TO KEEP A CHANCE OF SHRA/TSRA IN THE TAFS. CONFIDENCE IS LOW AS TO THE TIMING AND COVERAGE OF PCPN THIS MORNING...SO WILL KEEP THE TEMPO GROUP IN THE FORECAST. LATEST RADAR IMAGERY ONLY INDICATES SOME ISOLD ECHOES OVER NRN IL/IN...ASIDE FROM THE ONGOING CONVECTION OVER NWRN INDIANA...EAST OF GYY. BUT GIVEN THE MOIST ENVIRONMENT...WILL LEAVE THE TEMPO IN THE FORECAST FOR A LITTLE LONGER AS THERE IS A CHANCE FOR INCREASED DEVELOPMENT THROUGH THE MORNING HOURS. WHILE THERE MAY STILL BE LOW CHANCES FOR ADDITIONAL SHRA/TSRA THROUGH THE AFTERNOON AND INTO EARLY EVENING...CONFIDENCE IN TIMING AND COVERAGE IS EVEN LOWER...SO WILL KEEP THE FORECAST DRY THROUGH THIS EVENING. THE NEXT...MORE SIGNIFICANT CHANCE FOR SHRA/TSRA WILL COME OVERNIGHT THURSDAY NIGHT AS A STRONG COLD FRONT APPROACHES THE REGION. THE CONVECTIVE ACTIVITY SHOULD LARGELY BE INVOF THE FRONT...WHICH SHOULD MOVE INTO NWRN IL BY LATE THIS EVENING AND THEN REACH THE CHICAGO AREA TERMINALS. CONFIDENCE IS A LITTLE HIGHER WITH THIS SYSTEM...SO HAVE ADDED A TEMPO GROUP THE END OF THE RFD TAF...AND A PROB30 GROUP TO THE 30-HR EXTENDED PERIOD OF THE ORD TAF. AS TIMING OF THE FRONTAL PASSAGE BECOMES A BIT MORE CERTAIN...WILL LIKELY NEED TO CARRY A PREVAILING GROUP TSRA. FOR WINDS...THERE IS LITTLE CHANGE TO THE GOING FORECAST. WINDS SHOULD REMAIN SLY THROUGH THE NIGHT AT ARND 10KT. THERE IS A CHANCE FOR SOME HIGHER GUSTINESS IF ADDITIONAL PCPN DOES DEVELOP. WITH DAYTIME WARMING AND SOME BREAKING UP OF CLOUD COVER...HIGHER GUSTS SHOULD MIX DOWN TO THE SFC AND FREQUENT GUSTS TO ARND 20KT SHOULD PREVAIL FROM LATE MORNING THROUGH EARLY EVENING. AS THE FRONTAL TROUGH APPROACHES THE MISSISSIPPI RIVER LATER TODAY...WIND DIRECTION SHOULD VEER A LITTLE WEST OF SOUTH TO 200-210 DEGREES BEFORE QUICKLY SHIFTING TO NWLY WITH THE FROPA. //ORD AND MDW CONFIDENCE...UPDATED 06Z... * LOW CONFIDENCE ON SHRA/TSRA THROUGH LATE THIS MORNING. * MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS. * MEDIUM TO HIGH CONFIDENCE IN ADDITIONAL SHRA/TSRA LATE THURSDAY NIGHT INTO FRIDAY MORNING WITH THE FROPA...BUT LOWER CONFIDENCE IN EXACT TIMING. * HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS. KREIN //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...SHRA/TSRA LIKELY THROUGH LATE AFTERNOON...SHRA POSSIBLY LINGERING INTO THE EVENING. MVFR POSSIBLE. WIND SHIFT FROM SWLY TO NWLY IN THE AFTERNOON. SATURDAY THROUGH TUESDAY...VFR. WX NIL. KJB && .MARINE... 256 PM CDT AN AREA OF LOW PRESSURE CENTERED OVER THE DAKOTAS IS TO WEAKEN SLIGHTLY AS IT TRACKS NORTHEAST TO SOUTHERN CANADA BY MIDDAY THURSDAY. THE LOW THEN DEEPENS FRIDAY AND MOVES ACROSS JAMES BAY. AN ASSOCIATED COLD FRONT WILL MOVE SOUTHEASTWARD AND ACROSS LAKE MI DURING FRIDAY SHIFTING SOUTH AND SOUTHWESTERLY WINDS TO OUT OF THE WEST AND NORTHWEST AND INCREASING TO STRONG BREEZES. AS LARGE HIGH PRESSURE BUILDS SOUTHEASTWARD ACROSS THE WESTERN GREAT LAKES FRIDAY THROUGH SUNDAY WINDS WILL GRADUALLY RELAX AS THEY VEER THROUGH NORTH AND EAST TO SOUTHEAST. TRS && .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
459 AM EDT THU SEP 19 2013 .SYNOPSIS... ISSUED AT 454 AM EDT THU SEP 19 2013 MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA TODAY...MAKING IT FEEL MUCH MORE HUMID AND IT WILL BE WARMER AS WELL. A COUPLE OF WEAK UPPER LEVEL DISTURBANCES WILL COMBINE WITH THE MOISTURE TO PRODUCE A CHANCE OF SHOWERS AND THUNDERSTORMS TODAY AND TONIGHT. A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS IS EXPECTED ON FRIDAY AS A STRONG COLD FRONT MOVES THROUGH. TEMPERATURES WILL COOL BACK BELOW NORMAL FOR THE WEEKEND. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 454 AM EDT THU SEP 19 2013 MESOSCALE CONVECTIVE VORTEX...MCV...WHICH MOVED OUT OF IA YESTERDAY AND INTO IL LAST EVENING HAS BEEN SLOWLY MOVING ACROSS NORTHERN INDIANA EARLY THIS MORNING. THIS FEATURE INTERACTED WITH THETA E RIDGE ADVECTING ACROSS THE REGION ALONG WITH PRECIPITABLE WATER VALUES OVER 1.5 INCHES. THE RESULT WAS SLOW MOVING THUNDERSTORMS WITH SOME TRAINING OVER WESTERN AREAS. DUAL POL RADAR ESTIMATES OF BETWEEN 2 AND 5 INCHES OF RAIN IN SOUTHWEST PULASKI AND WHITE COUNTIES PROMPTED ISSUANCE OF FLASH FLOOD WARNING AS FFG WAS AROUND 3 INCHES. RADAR SHOWING THIS PCPN FINALLY COMING TO AN END. HOWEVER...ANOTHER LINE OF TSRA HAS DEVELOPED ON LEADING EDGE OF SECONDARY THETA E MAX WITH LOW LEVEL JET ADDING CONVERGENCE AND THIS LINE IS MOVING EAST. HAVE INCLUDED SCATTERED TO NUMEROUS THUNDERSTORMS THROUGH DAYBREAK TO ACCOUNT FOR BOTH AREAS OF PRECIPITATION. SHOULD SEE ALL ACTIVITY END/MOVE OUT OF THE AREA SHORTLY AFTER DAYBREAK. REMAINDER OF DAY IN FLUX AS SUBSIDENCE FROM DEPARTING MCV SHOULD STABILIZE LOWER LEVELS. HOWEVER...BREAKS IN CLOUDS TO DEVELOP WITH PARTLY CLOUDY EXPECTED AGAIN TODAY. 925-850MB TEMPS WARM A FEW DEGREES FROM YESTERDAY AND HIGHS EXPECTED TO CLIMB WELL INTO 80S. MODEST INSTABILITY DEVELOPS THIS AFTERNOON WITH PEAK HEATING AND MOISTURE RICH AIR AS SFC DEW POINTS CLIMB INTO UPPER 60S. NAM12 SHOWING MUCAPES OVER 3000 J/KG BUT LIKELY OVERDONE GIVEN ITS DEWPOINTS INTO LOWER 70S. HAVE TRENDED POPS DOWN TO SLIGHT CHANCE MID MORNING INTO EARLY AFTERNOON WITH A TREND BACK UP TO LOW CHANCE THIS AFTERNOON WITH ANY DEVELOPMENT WITH PEAK HEATING. MODELS CONTINUE TO BE RATHER AGGRESSIVE WITH CONVECTIVE DEVELOPMENT TONIGHT WELL AHEAD OF MAIN COLD FRONT. KEPT SIMILAR TREND OF INCREASING POPS THROUGH THE NIGHT AS FRONT NEARS. LOCALIZED HEAVY RAINFALL STILL POSSIBLE THROUGH THE SHORT TERM PERIOD GIVEN HIGH PWATS AND THETA E AIR ALONG WITH TRAINING POTENTIAL. && .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 454 AM EDT THU SEP 19 2013 A COLD FRONT WILL BE MOVING SOUTHEAST INTO THE AREA FRIDAY. GFS/ECMWF TELECONNECTIONS SUPPORT THE TROF STARTING TO BECOME POSITIVELY TILTED BY LATE SATURDAY. CONCERNS FRIDAY AND FRIDAY NIGHT FOR THUNDERSTORMS WITH HEAVY RAIN GIVEN THE LIKELIHOOD OF BACKBUILDING CELLS. GFS BUFKIT FOR SEVERAL RUNS CONTINUES TO SHOW MEAN CLOUD LAYER WINDS COMBINED WITH A LOW LEVEL JET FAVORING LITTLE NET CELL MOVEMENT. ALSO FAVORING HEAVY RAIN IS THAT THE WARM CLOUD LAYER WILL LIKELY BE GENERALLY OVER 11K FEET DEEP WITH PRECIPITABLE WATER VALUES BETWEEN 1.7 TO 1.9 INCHES. THIS IS AROUND 2 STANDARD DEVIATIONS AND APPROACHING THE 99TH PERCENTILE PER UPPER AIR CLIMATE DATA. ALSO...CAPES SHOULD GENERALLY BE UNDER 1000 J/KG. THE SEVERE WEATHER POTENTIAL LOOKS MORE MARGINAL FRIDAY GIVEN LIMITED/SKINNY CAPES AND WEAK/STABLE MID LEVEL LAPSE RATES. HOWEVER...UPPER LEVEL DYNAMICS INCLUDING THE TRANSLATION OF THE RIGHT ENTRANCE OF A 100+ KNOT JET SHOULD HELP TO STRENGTHEN STORMS. USED THE ECMWF/GFS TO PUT SOME DETAIL IN THE TIMING OF THE SHOWERS AND STORMS FRIDAY. ALSO...RAISED RAINFALL AMOUNTS GIVEN THE ABOVE REASONING. OTHERWISE...LINGERING SHOWERS SHOULD END EARLY SATURDAY FOLLOWED BY DRY CONDITIONS THE REST OF THE PERIOD. TRIED TO BLEND TEMPERATURES TOWARD THE GFS OPERATIONAL RUN MEX WHICH APPEARS ON TRACK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 454 AM EDT THU SEP 19 2013 A DIFFICULT AVIATION FORECAST THIS PERIOD WITH MESOSCALE CONVECTIVE SYSTEM OVER THE AREA AND HEADING TOWARD KFWA. MODEL GUIDANCE STRUGGLING WITH THIS FEATURE BUT HIRES HRRR HAS A REASONABLE HANDLE ON MOVEMENT. EXPECT SHOWERS INTO KFWA AROUND 06Z WITH OCCASIONAL THUNDER FOR A FEW HOURS. RADAR SHOWS A TRAILING CONVECTIVE LINE PARALLEL TO MEAN FLOW AND SHEAR VECTOR OVER NORTHWEST INDIANA. THIS IS SLOWLY DRIFTING EAST WHILE ALSO SHOWING SIGNS OF WEAKENING. MEANWHILE...NEW DEVELOPMENT OCCURRING OVER LAKE MICHIGAN. HAVE INCLUDED A VCTS AT KSBN STARTING AROUND 08Z FOR THIS ACTIVITY AND WILL MONITOR MOVEMENT FOR POSSIBLE UPDATE. OTHERWISE SATELLITE SHOWING MID LEVEL CLOUD DECK DEVELOPING UPSTREAM IN WARM AND MOIST SOUTHERLY FLOW. CLOUD COVER AGAIN A PROBLEM FOR TODAY BUT EXPECT MAINLY VFR CIGS AFTER DAYBREAK WITH AN OUTSIDE CHANCE OF SOME MVFR CIGS AFTER RAIN ENDS BEFORE SUNRISE. CONFIDENCE LOW IN CONVECTIVE DEVELOPMENT TODAY. MOIST LOW LEVELS BUT NO STRONG TRIGGER AND MODELS ALL OVER THE PLACE. HAVE OPTED TO LEAVE OUT OF TAFS GIVEN UNCERTAINTY IN COVERAGE BUT A LOW CHANCE WILL EXIST THROUGH THE PERIOD AND INTO FRIDAY WHEN STRONG COLD FRONT ARRIVES. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...LASHLEY SHORT TERM...LASHLEY LONG TERM...SKIPPER AVIATION...LASHLEY 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
146 AM EDT THU SEP 19 2013 .SYNOPSIS... ISSUED AT 800 PM EDT WED SEP 18 2013 INCREASED MOISTURE WILL CONTINUE TO LIFT NORTHEAST INTO THE AREA THROUGH THURSDAY. A COUPLE OF WEAK UPPER LEVEL DISTURBANCES WILL COMBINE WITH THIS MOISTURE TO PRODUCE A CHANCE OF SHOWERS AND THUNDERSTORMS TONIGHT THROUGH THURSDAY NIGHT. A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS IS EXPECTED ON FRIDAY AS A STRONGER UPPER LEVEL SYSTEM SHIFTS INTO THE UPPER MIDWEST ALLOWING A COLD FRONT TO APPROACH FRIDAY AFTERNOON AND EVENING. WARMER CONDITIONS CAN BE EXPECTED THURSDAY IN ADVANCE OF THE FRONT...COOLING BACK BELOW NORMAL FOR THE WEEKEND. && .UPDATE... ISSUED AT 800 PM EDT WED SEP 18 2013 A FAIRLY COMPACT MCV HAS ALLOWED FOR SCATTERED SHOWERS AND THUNDERSTORMS TO BE MAINTAINED INTO NORTHWEST INDIANA THIS EVENING. THE STRONGEST OF THESE CELLS EARLY THIS EVENING IS LOCATED ON THE SOUTHERN PERIPHERY OF THE MCV ACROSS JASPER COUNTY IN NORTHWEST INDIANA...BUT SHOULD GRADUALLY WEAKEN AS IT MOVES OFF PRIMARY 500-1000 J/KG MUCAPE AXIS OVER NEXT FEW HOURS. POTENTIAL OF SURFACE BASED INSTABILITY ALSO SHOULD WANE DURING THIS TIME FRAME...ALTHOUGH MARGINAL CAPES ON THE ORDER OF 500 J/KG FOR SLIGHTLY ELEVATED PARCELS SHOULD PERSIST. SCATTERED THUNDERSTORMS HAVE ALSO DEVELOPED ON NORTHERN EDGE OF MCV ACROSS NORTHEAST ILLINOIS...BUT CONFIDENCE REMAINS LOW THAT THESE THUNDERSTORMS WILL SURVIVE INTO WESTERN PORTIONS OF THE AREA TOWARD MIDNIGHT. SHORT TERM GUIDANCE IS IN FAIRLY GOOD AGREEMENT IN SECONDARY LOW LEVEL THETAE SURGE WORKING INTO ESPECIALLY NORTHERN LOCATIONS OVERNIGHT AS WEAK SHORT WAVE ACROSS NORTHERN IOWA TOPS THE UPPER LEVEL RIDGE IN PLACE. THIS COULD RESULT IN ADDITIONAL ELEVATED CONVECTION OVERNIGHT WHICH IS ALREADY COVERED IN INHERITED FORECAST WITH SLIGHT CHANCE POPS ACROSS NORTHERN TWO THIRDS OF THE AREA. ONLY TWEAK TO PREVIOUS FORECAST WAS TO INCREASE POPS ACROSS THE WEST THIS EVENING TO ACCOUNT FOR MCV EVOLUTION. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 350 PM EDT WED SEP 18 2013 LEE CYCLOGENESIS IS NOW WELL UNDERWAY ACROSS THE NORTHERN PLAINS AS MODERATE AMPLITUDE PV ANOMALY LIFTS OUT OF THE NORTHERN ROCKIES. WITH A PERSISTENT SURFACE HIGH ACROSS THE EAST COAST...THIS HAS OPENED THE DOOR FOR SOUTHWEST FLOW AND BROAD THETA-E ADVECTION LOCALLY. VERY LITTLE FOCUS FOR SUSTAINED UVM IN THE WAKE OF THIS MORNING`S SHORTWAVE PASSAGE THOUGH. LINGERING EFFECTS OF VERY DRY CANADIAN AIRMASS ARE STILL BEING FELT WITH LITTLE MORE THAN AN ISOLATED SPRINKLE ACROSS THE AREA EARLIER TODAY. CONVECTIVE LINE ACROSS NORTHERN ILLINOIS IS EXPECTED TO DISSIPATE AS IT INTERSECTS THIS VERY DRY AND STABLE AIRMASS LATER THIS EVENING BUT A FEW DECAYING SHOWERS MAY BE POSSIBLE IN OUR WEST AS SUGGESTED BY SOME PREVIOUS RUNS OF THE HRRR. THE CHANCES OF RAIN WILL THEN INCREASE AGAIN BY LATE TONIGHT AND INTO TOMORROW BUT THE FORCING WILL REMAIN RATHER WEAK AND BROAD. PRECIP CHANCES WILL LARGELY DEPEND ON NOCTURNAL STRENGTHENING OF THE LLJ DRAPED ACROSS THE MIDWEST. THOUGH THE BEST MOISTURE CONVERGENCE WILL INITIALLY BE FOCUSED NORTHWEST OF OUR CWA...SLIGHT VEERING IS EXPECTED BY EARLY TOMORROW MORNING WITH ANOTHER SURGE OF INCREASING WAA/FRONTOGENESIS ACROSS OUR NORTHWEST COUNTIES. 305K SYSTEM RELATIVE ISENTROPIC ASCENT IS NOT OVERLY IMPRESSIVE AND THERE WILL BE A LIMITED TIME WINDOW BEFORE THE LLJ WEAKENS LATER THURSDAY MORNING BUT SHOULD BE ENOUGH FORCING AND AVAILABLE MOISTURE TO SUPPORT A FEW SCATTERED SHOWERS AND PERHAPS AN ISOLATED RUMBLE OF THUNDER...MAINLY IN OUR NORTHWEST. INCREASING WAA AND ASSOCIATED CLOUD COVER WILL ALSO LEAD TO MILD OVERNIGHT LOWS WITH VALUES LIKELY NOT DROPPING MUCH BELOW THE LOW TO MID 60S. SOUTHERN GREAT LAKES WILL BE FIRMLY IN THE WARM SECTOR TOMORROW. 850MB TEMPS CLIMB INTO THE UPPER TEENS...YIELDING AFTERNOON HIGHS IN THE LOW TO MID 80S DESPITE A FAIR AMOUNT OF CLOUD COVER. CONTINUED MOISTURE ADVECTION WILL ALSO PUSH SURFACE DEWPOINTS INTO THE MID TO UPPER 60S...RAISING THE PROSPECTS FOR SURFACE BASED CONVECTION. APPROACHING TROUGH AND OVERALL MODEST NATURE OF DOWNSTREAM RIDGE RESULTS IN VERY LITTLE CAP AS WELL. FORCING WILL BE RATHER ILL-DEFINED BUT MODEST INSTABILITY IN A REGION OF BROAD WARM/MOIST AIR ADVECTION SHOULD SUPPORT AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS BY THE AFTERNOON. NO SEVERE WEATHER EXPECTED GIVEN ONLY ABOUT 1500 J/KG OF SBCAPE AND 15-20 KTS DEEP LAYER SHEAR. && .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 350 PM EDT WED SEP 18 2013 STRONG UPR LEVEL TROF OVER THE NRN ROCKIES THIS AFTN IS EXPECTED TO MOVE EAST TO THE UPR MS VALLEY THU NGT AND ACROSS THE GRTLKS FRI-FRI NGT. AS THIS SYSTEM APPROACHES... MOISTURE AND LIFT SHOULD GRDLY INCREASE FROM NW-SE ACROSS THE CWA THU NGT CAUSING SCT SHOWERS/TSTMS. MODEST S-SW SFC GRADIENT WINDS WILL PERSIST THROUGH THE NGT RESULTING IN MILD LOW TEMPS IN THE U60S. SFC CDFNT ASSOCIATED WITH THIS TROF IS EXPECTED MOVE FROM NW-SE ACROSS OUR CWA FRI AFTN-NGT WITH RAIN CHANCES PEAKING DURING THIS TIMEFRAME. GIVEN GOOD INTRA MODEL AND RUN-RUN CONTINUITY IN THIS REGARD... HAVE TRENDED POPS UP FRI. MODELS SUGGEST MODERATE SFC BASED INSTABILITY WILL DVLP IN OUR AREA FRI AS STRENGTHENING 0-6KM SHEAR ASSOCIATED WITH THE UPR TROF MOVES IN FROM THE NW. STILL APPEARS TO BE JUST A SMALL CHC INGREDIENTS NEEDED FOR SEVERE STORMS WILL COME TOGETHER OVER OUR AREA... WITH BULK OF STRONG SHEAR STILL FCST TO LAG BEST INSTABILITY. LOCALLY HEAVY RAINFALL REMAINS A POSSIBILITY FRI/FRI EVE AS PROGGED SMALL MBE VECTORS... VERY MOIST AIRMASS... AND DEEP WARM CLOUD LAYER SUGGEST EFFICIENT RAINFALL PROCESS IN CONVECTION WITH POTENTIAL FOR SOME TRAINING/BACKBUILDING CELLS... THOUGH GIVEN DRY ANTECEDENT MOISTURE CONDITIONS ACROSS MOST OF OUR CWA... EXPECT ANY FLOODING WILL BE LOCALIZED. LEANED TOWARD WARMER MOS GUIDANCE FOR HIGHS FRIDAY AS GOOD GRADIENT MIXING OF WARM AIRMASS EXPECTED DURING DRY PERIODS. HIGH PRESSURE RIDGE WILL BUILD INTO THE AREA SATURDAY BRINGING ANY LINGERING SHOWERS ERN PORTION OF CWA TO AN END EARLY WITH CAA RESULTING IN TEMPS A BIT BLO NORMAL. THIS RIDGE IS EXPECTED TO LINGER OVER THE WRN GRTLKS INTO THE MIDDLE OF NEXT WEEK AS ANOTHER STRONG TROF DIGS INTO THE WRN U.S. AND A CUT-OFF LOW FORMS OVER THE SERN U.S. AND THEN LIFTS NEWD UP THE ERN SEABOARD. THIS SHOULD RESULT IN A PROLONGED PERIOD OF DRY WX WITH TEMPS MODERATING TO A LITTLE ABOVE NORMAL EARLY-MIDDLE NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 145 AM EDT THU SEP 19 2013 A DIFFICULT AVIATION FORECAST THIS PERIOD WITH MESOSCALE CONVECTIVE SYSTEM OVER THE AREA AND HEADING TOWARD KFWA. MODEL GUIDANCE STRUGGLING WITH THIS FEATURE BUT HIRES HRRR HAS A REASONABLE HANDLE ON MOVEMENT. EXPECT SHOWERS INTO KFWA AROUND 06Z WITH OCCASIONAL THUNDER FOR A FEW HOURS. RADAR SHOWS A TRAILING CONVECTIVE LINE PARALLEL TO MEAN FLOW AND SHEAR VECTOR OVER NORTHWEST INDIANA. THIS IS SLOWLY DRIFTING EAST WHILE ALSO SHOWING SIGNS OF WEAKENING. MEANWHILE...NEW DEVELOPMENT OCCURRING OVER LAKE MICHIGAN. HAVE INCLUDED A VCTS AT KSBN STARTING AROUND 08Z FOR THIS ACTIVITY AND WILL MONITOR MOVEMENT FOR POSSIBLE UPDATE. OTHERWISE SATELLITE SHOWING MID LEVEL CLOUD DECK DEVELOPING UPSTREAM IN WARM AND MOIST SOUTHERLY FLOW. CLOUD COVER AGAIN A PROBLEM FOR TODAY BUT EXPECT MAINLY VFR CIGS AFTER DAYBREAK WITH AN OUTSIDE CHANCE OF SOME MVFR CIGS AFTER RAIN ENDS BEFORE SUNRISE. CONFIDENCE LOW IN CONVECTIVE DEVELOPMENT TODAY IN WAKE OF MCV. MOIST LOW LEVELS BUT NO STRONG TRIGGER AND MODELS ALL OVER THE PLACE. HAVE OPTED TO LEAVE OUT OF TAFS GIVEN UNCERTAINTY IN COVERAGE BUT A LOW CHANCE WILL EXIST THROUGH THE PERIOD AND INTO FRIDAY WHEN STRONG COLD FRONT ARRIVES. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...MARSILI SYNOPSIS...MARSILI SHORT TERM...AGD LONG TERM...JT AVIATION...LASHLEY 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 INDIANAPOLIS IN
1230 AM EDT THU SEP 19 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 358 PM EDT WED SEP 18 2013 A BROAD UPPER LEVEL RIDGE TO OUR SOUTH IS BEING ROUNDED BY VERY WEAK AND VERY SUBTLE UPPER LEVEL WAVES...POORLY RESOLVED BY GUIDANCE. THESE WEAK WAVES MAY BE ABLE TO SPARK A SHOWER OR STORM AT TIMES THROUGH LATE THURSDAY NIGHT INTO FRIDAY NIGHT...WHEN THE MAIN FRONTAL SYSTEM WILL PUSH THROUGH THE AREA AND BRING A MORE SUBSTANTIAL OPPORTUNITY FOR STORMS TO THE AREA BEFORE DRY AND COOLER CONDITIONS RETURN FOR THE REMAINDER OF THE FORECAST PERIOD. && .NEAR TERM /REST OF TONIGHT/... ISSUED AT 946 PM EDT WED SEP 18 2013 RADAR LOOP SHOWS SOME STORMS IN NORTHWEST INDIANA WITH A LITTLE SHOWER ALSO OVER NORTHERN CARROLL COUNTY. THE LARGER AREA OF STORMS IS MOVING SOUTHEAST. LOOKING AT HRRR MODEL OUTPUT IT APPEARS THAT THIS WILL WEAKEN AS IT HEADS THIS WAY SIMILAR TO THE ECHOES THAT ARE NOW ONLY A BRIEF SHOWER. STILL IT LOOKS POSSIBLE THAT STORMS COULD REACH THE NORTHERN COUNTIES OF THE AREA OVER THE NEXT FEW HOURS AND THUS WENT WITH A SLIGHT TO LOW END CHANCE THERE DURING THIS TIME. ALSO SEEING SOME LIGHT RAIN OVER CENTRAL ILLINOIS PROMPTED BY A WEAK UPPER WAVE AND SOME ISENTROPIC LIFT AND THIS COULD MOVE INTO THE AREA AFTER 6Z...SO WENT WITH A SLIGHT CHANCE ACROSS ALL OF CENTRAL INDIANA THEN. THIS SHOULD ALSO COVER SOME REDEVELOPMENT OVER THE NORTHEASTERN COUNTIES THAT THE HRRR IS SHOWING...ALTHOUGH CONFIDENCE IN THIS SOLUTION IS LOW AND THUS NO HIGHER THAN 20 POPS WILL BE USED DURING THAT TIME. GOING LOW TEMPERATURES IN THE MIDDLE 60S LOOK GOOD BASED ON EXPECTED CLOUD COVER AND CURRENT TEMPERATURES. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... ISSUED AT 358 PM EDT WED SEP 18 2013 MAY SEE SOME SHOWERS OR STORMS DEVELOP FROM MIDDAY ONWARD TOMORROW...AGAIN NO MORE THAN SCATTERED IN NATURE. HIGHER POPS ARE ONLY MERITED FRIDAY INTO FRIDAY NIGHT AS THE FRONT FINALLY PUSHES THROUGH THE AREA. SPC SEE TEXT OUTLOOK DAY 3 APPEARS REASONABLE GIVEN THE TIME OF DAY THE FRONT IS EXPECTED...BUT INSTABILITY AND SHEAR ARE MODEST AT BEST AND DO NOT EXPECT MUCH MORE THAN ISOLATED SEVERE IF THAT. ON TEMPS...CONSENSUS NUMBERS LOOKED OK THROUGHOUT GIVEN EXPECTED THICKNESSES AND PRECIP COVERAGE...EXCEPT FOR SATURDAY WHERE A WARMER MOS BLEND WAS PREFERRED WITH SKIES LIKELY TO CLEAR AND AMPLE SUN EXPECTED. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... ISSUED AT 220 PM EDT WED SEP 18 2013 DRY FORECAST THIS PERIOD WITH SEASONABLE TEMPERATURES. GFS AND ECMWF DEPICT A CUT OFF UPPER LOW MOVING THROUGH THE APPALACHIANS EARLY IN THE PERIOD WHILE RIDGING ALOFT AND STRONG SUBSIDENCE OVER THE MISSISSIPPI RIVER VALLEY PROVIDES A NORTHERLY FLOW OF AIR AS IT SLOWLY BUILDS EAST DURING THE PERIOD. AS THE RIDGE MOVES EAST OVER INDIANA BY THE MIDDLE OF NEXT WEEK...TEMPS WILL SLOWLY MODERATE TO SLIGHTLY ABOVE NORMAL AS RETURN FLOW BEGINS. && .AVIATION /DISCUSSION FOR THE 190600Z TAFS/... ISSUED AT 1230 AM EDT THU SEP 19 2013 MVFR CONDITIONS WILL BE POSSIBLE EARLY THIS MORNING. A RETURN TO VFR IS EXPECTED BY LATE MORNING. MODELS DEPICT A LOWERING CIGS AND VISIBILITIES DIURNALLY OVERNIGHT AS HIGH DEW POINTS AND DIURNAL COOLING IS ONGOING. THEN MODELS ONCE AGAIN HINT AT ANOTHER BIT OF LIFT PUSHING THROUGH THE AREA ON LATE THIS AFTERNOON...HOWEVER...CONFIDENCE IN THIS WEAK FEATURES REMAIN LOW AND WILL STICK WITH VFR AND VCSH ATTM. BETTER CHANCES FOR RAIN WILL COME LATER ON FRIDAY...JUST OUTSIDE OF THE TAF FORECAST PERIOD. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...NIELD NEAR TERM...CP SHORT TERM...NIELD LONG TERM....PUMA AVIATION...SMF VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1145 PM CDT WED SEP 18 2013 .UPDATE... ISSUED AT 847 PM CDT WED SEP 18 2013 AN UPDATE WAS JUST SENT TO INCREASE POPS OVER THE NORTH HALF OF THE AREA AFTER MIDNIGHT. LLJ PROGGED TO STRENGTHEN TO 40+KTS LATE TONIGHT AND IS POINTED AT NORTHEAST IOWA DURING THE EARLY MORNING HOURS. SATELLITE IMAGERY IS SHOWING AN AREA OF MID CLOUDS DRIFTING EAST THROUGH NORTH CENTRAL IA AND THEY SHOULD BE OVER THE NE QUARTER OF THE STATE BY MIDNIGHT...WHERE THE NOSE OF THE LLJ IS AIMED. THE PAST SEVERAL RUNS OF THE HRRR HAVE BEEN CONSISTENTLY DEVELOPING CONVECTION IN THE SAME AREA. GIVEN THESE FACTORS THERE WAS ENOUGH CONFIDENCE TO INCREASE POPS INTO THE CHANCE CATEGORY BETWEEN 06Z AND 12Z. DLF && .SYNOPSIS... ISSUED AT 310 PM CDT WED SEP 18 2013 12Z UA ANALYSIS HAD AN 850MB LOW NEAR KBIS WITH A DEVELOPING WARM FRONT RUNNING SOUTHEAST TO KSTL. A LLJ RAN FROM WEST TEXAS INTO SOUTHWEST IOWA AND DEW POINTS WERE IN THE MID TEENS FROM MEXICO INTO SOUTHERN MINNESOTA. SATELLITE/RADAR TRENDS SHOW THE SMALL COMPLEX OF STORMS MOVING INTO NORTHEAST IOWA WITH GENERALLY CLEAR SKIES ACROSS THE PLAINS AND IOWA. 18Z SFC ANALYSIS HAS A LOW NEAR KPIR WITH A WARM FRONT RUNNING SOUTHEAST TO NEAR KMLI AND THEN SOUTH TO NEAR K3LF. RAIN COOLED AIR REMAINED ACROSS NORTHEAST IOWA AND NORTHWEST ILLINOIS. DEW POINTS WERE IN THE 60S ACROSS THE MIDWEST WITH POCKETS OF 70S IN THE SOUTHERN PLAINS. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 310 PM CDT WED SEP 18 2013 SATELLITE TRENDS INDICATE LITTLE IN THE WAY OF NEW CLOUDS HAVE FORMED DURING THE AFTERNOON SO THE THREAT OF NEW CONVECTION PRIOR TO SUNSET IS VERY LOW. THE MCS AND LIFT TOOLS ARE SUGGESTING SOME ISOLATED WEAK CONVECTION MAY DEVELOP OVER THE AREA BY LATE EVENING AND MOVE EAST. HOWEVER...THE BETTER FORCING/MOISTURE IS WEST OF THE AREA. THE MCS AND LIFT TOOLS ARE SUGGESTING ANOTHER STORM COMPLEX DEVELOPING ALONG THE IA/MO BORDER LATE TONIGHT AND POSSIBLY ARRIVING IN THE WESTERN CWFA AROUND SUNRISE THURSDAY. THUS MOST OF THE AREA SHOULD SEE DRY CONDITIONS TONIGHT. IF THE STORM COMPLEX DEVELOPS AS SUGGESTED ALONG THE IA/MO BORDER...THEN THIS COMPLEX WOULD MOVE ACROSS THE WESTERN HALF OF THE CWFA DURING THE MORNING. CLOUD COVER/PRECIPITATION MAY MAKE IT DIFFICULT TO ACHIEVE HIGHS IN THE MID AND UPPER 80S THURSDAY. NEW CONVECTION IS EXPECTED TO DEVELOP THURSDAY AFTERNOON AHEAD OF THE APPROACHING COLD FRONT. MOISTURE LEVELS IN THE ATMOSPHERE ARE PROJECTED TO BE QUITE HIGH UP INTO THE MID LEVELS. THUS THE POTENTIAL FOR ANY SEVERE STORMS APPEARS TO BE LOW. ..08.. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 310 PM CDT WED SEP 18 2013 MODERATE TO HEAVY RAIN EVENT THURSDAY NIGHT...THEN SEASONABLY COOL. OVERVIEW...INITIALIZATION AND VERIFICATION AVERAGE WITH MOST SOLUTIONS UNDERPLAYING MOISTURE IN CENTRAL PLAINS AND SW MONSOON PLUME. PACIFIC ENERGY IS ALSO UNDERPLAYED WITH 10 TO 20 METER HEIGHT FALLS UNDERDONE. THIS SHOWS UP IN SURFACE PRESSURE FIELDS. VERIFICATION AT 18Z SUPPORTS FORCING OF HI-RES ECMWF/UKMET AND NAM-WRF WITH HI- RES ECMWF CLOSEST ON MOISTURE FLUX WITH COOL FRONT PASSING THURSDAY NIGHT. THEN...EARLY FALL HIGH PRESSURE TO BRING SEVERAL DAYS OF NICE LATE SEPTEMBER WEATHER WITH LOW HUMIDITY. THURSDAY NIGHT...STRAIGHTFORWARD FORECAST. PW/S OF 1.5" OF DEEP MOISTURE AHEAD OF DEEP SURFACE AND UPPER LEVEL TROUGH TO BRING A LARGE SWATH OF SHOWERS AND THUNDERSTORMS. LITTLE OR NO SURFACE WAVE SUGGESTED AT THIS TIME...LOCAL TOOLS INDICATE ALMOST ALL THE AREA TO PICK UP .5 TO LOCALLY NEAR 1.5 INCHES OF RAIN. WENT WITH 80-90 POPS WITH FRONT PASSING BETWEEN MIDNIGHT AND 7 AM. DEEP MOISTURE...OVERNIGHT FORCING AND HIGH FREEZING LEVELS DO NOT SUPPORT A SEVERE RISK AT THIS TIME WITH STRONGEST STORMS PRODUCING MAYBE 30-40 MPH WINDS. LATER SHIFTS WILL NEED TO REASSESS AS NAM- WRF IS TOO UNSTABLE IN BL AS HAS BEEN MORE OFTEN THE CASE THIS WARM SEASON. NOTE: IF A WAVE FORMS...LOCALLY 2+ INCH AMOUNTS WILL BE POSSIBLE. FRIDAY...KEPT MORNING POPS EAST SECTIONS WITH CLEARING BY MID DAY AND BREEZING NW WINDS OF 10-20+ MPH. HIGHS MOSTLY 70-75F FOR A NICE DAY. FRIDAY NIGHT THROUGH WEDNESDAY...MOSTLY FAIR AND SLIGHTLY BELOW NORMAL TEMPERATURES AS CANADIAN HIGH PRESSURE DOMINATES. HIGHS GENERALLY UPPER 60S TO MIDDLE 70S WITH LOWS 45 TO 55 DEGREES. GOOD WEATHER FOR MOST OUTDOOR ACTIVITIES. ANOTHER PROMISING RAIN EVENT POSSIBLE BY LATE IN THE WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1140 PM CDT WED SEP 18 2013 THE MAIN CONCERN WILL BE THE THUNDERSTORM POTENTIAL OVERNIGHT. THERE ARE STILL INDICATIONS OF A THUNDERSTORM COMPLEX DEVELOPING OVER EAST CENTRAL IOWA AFTER MIDNIGHT AND MOVING NORTHEAST THROUGH NORTHWEST IL BY THURSDAY MORNING. IT APPEARS THE BETTER FORCING WILL BE NORTH OF I80 SO LIMITED THE MENTION OF THUNDER TO THE CID AND DBQ TAFS BETWEEN 10Z AND 14Z. OTHERWISE EXPECT MAINLY VFR CONDITIONS OVERNIGHT THURSDAY. A COLD FRONT WILL BE APPROACHING THE AREA THURSDAY AFTERNOON. THUNDERSTORMS AHEAD OF THE FRONT COULD REACH CID AND DBQ AS EARLY AS LATE THURSDAY AFTERNOON. THE THUNDERSTORMS WILL SPREAD SOUTHEAST DURING THE EVENING. THE STRONGEST STORMS SHOULD OCCUR LATE IN THE AFTERNOON AND EARLY IN THE EVENING. IFR/MVFR CONDITIONS WOULD ACCOMPANY THE STRONGER STORMS. ALSO SOUTHWEST WINDS AHEAD OF THE FRONT WILL GUST TO 20 TO 25KTS DURING THE AFTERNOON. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ UPDATE...DLF SYNOPSIS...08 SHORT TERM...08 LONG TERM...NICHOLS AVIATION...DLF
AREA FORECAST DISCUSSION
NWS GOODLAND KS
358 AM MDT THU SEP 19 2013 .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 358 AM MDT THU SEP 19 2013 FORECAST PROBLEMS WILL BE PRECIPITATION CHANCES TODAY...HOW COOL TO MAKE HIGHS AND LOWS THROUGH FRIDAY NIGHT AND HOW MUCH TO WARM THINGS UP ON SATURDAY. SATELLITE SHOWING AN ACTIVE FLOW FROM THE PACIFIC INTO NORTH AMERICA. THE FLOW WAS AMPLIFYING SOME OVER THE PACIFIC... ESPECIALLY ALONG THE WEST COAST. ONE SYSTEM IS PUSHING EAST ALONG THE U.S AND CANADIAN BORDER. OUTFLOW FROM THUNDERSTORM CLUSTER TO OUR NORTH HAS PUSHED THROUGH THE AREA WITH A COLD FRONT APPROACHING FROM THE NORTHWEST. AT JET LEVEL...THE SREF WAS DOING A LITTLE BETTER WITH THE JET DEPICTION OVER OUR AREA. AT MID LEVELS...MODELS WERE HAVING A LITTLE TROUBLE THE SPEED AND AMPLITUDE OF THE NORTHERN LOW. AT THIS TIME IT APPEARS THE GFS AND UKMET WERE DOING A LITTLE BETTER THAN THE ECMWF AND CANADIAN. THE RUC WAS CATCHING THE INITIAL WIND FIELD THE BEST WITH THE ECMWF NOT TOO FAR BEHIND. THE UKMET AND GFS WERE DOING A LITTLE BETTER THAN THE OTHER OUTPUT ON THE LOW LEVEL THERMAL FIELD. TODAY/TONIGHT...INTERESTING PRECIPITATION FORECAST. INITIAL ROUND OF THUNDERSTORMS WERE CAUSED BY INITIAL SURFACE TROUGH AND OUTFLOW BOUNDARY FROM CLUSTER OF THUNDERSTORMS THAT MOVED TO THE NORTH OF OUR FORECAST AREA. HOWEVER ADDITIONAL DEVELOPMENT IS NOW OCCURRING IN ADVANCE OF COLD FRONT WHICH IS VERY NEAR THE NORTHWEST CORNER OF THE FORECAST AREA. ALSO AT THIS TIME...MAIN SHORTWAVE TROUGH ROTATING AROUND NORTHERN UPPER LOW IS BEGINNING TO MOVE IN FROM THE WEST. ALSO THE RIGHT REAR QUADRANT OF THE JET IS NEAR/OVER THE WESTERN END OF THE FORECAST. DURING THE DAY THEY ALL HANDLE IT DIFFERENTLY. HOWEVER...BY THE END OF THE AFTERNOON INTO THE EARLY AFTERNOON...THE RIGHT REAR QUADRANT IS OVER OR NEAR THE EASTERN END OF THE AREA. IN ADVANCE OF ALL THESE FEATURES THERE APPEARS ENOUGH ELEVATED CAPE WITH FAVORABLE THETA-E LAPSE RATES TO ALLOW FOR A GOOD RESPONSE TO THE LIFT. AT THIS TIME IT LOOKS LIKE THE FAVORED AREA FOR THUNDERSTORMS IS ALONG AND EAST OF THE COLORADO BORDER...GETTING HIGHER AS YOU GO EAST. KEPT THIS GENERAL IDEA FROM THE DAY SHIFT BUT RAISED POPS SLIGHTLY FURTHER EAST. THUNDERSTORMS LOOK TO BE DONE BY LATE IN THE DAY. DEFINITELY LOOKS COOLER. THE QUESTION IS HOW MUCH. THE AMOUNT OF TEMPERATURE CHANGE OVER YESTERDAY WOULD YIELD SLIGHTLY COOLER TEMPERATURES THAN WHAT I HAVE IN THERE NOW. DID MAKE SLIGHT ADJUSTMENTS COOLER IN LINE WITH THE BIAS ADJUSTMENT TO THE 850 MB TEMPERATURES. THIS TENDED TO BE IN THE MIDDLE OF THE GUIDANCE. WILL BE A RATHER COOL NIGHT TONIGHT WITH LITTLE CLOUD COVER AND LIGHT WINDS. MODELS DIFFER ON WHERE THE LIGHTEST WINDS WILL BE. AT THIS TIME IT LOOKS THEY WILL BE IN THE WESTERN AND NORTHERN SECTIONS AND ADJUSTED ACCORDINGLY. FRIDAY/FRIDAY NIGHT...MID/UPPER RIDGE BUILDING INTO THE AREA WILL MAKE FOR DRY CONDITIONS AND LITTLE TO NO CLOUD COVER. SURFACE RIDGE JUST PULLING OFF TO THE EAST DURING THE DAY WITH LIGHT AND VARIABLE WINDS...ESPECIALLY IN THE EAST. MODELS ARE INDICATING TEMPERATURES NEAR WHAT THEY ARE TO BE TODAY. ONLY MADE SLIGHT ADJUSTMENTS BASED ON THAT. SOME DIFFERENCES IN HOW COOL TO MAKE THE MINS. THE NAM STARTS WARM ADVECTION MUCH FASTER WITH THE OTHER MODELS SLOWER. IT SHOULD BE WARMER BUT AM NOT GOING AS WARM AS THE NAM. SATURDAY/SATURDAY NIGHT...MID/UPPER LEVEL RIDGE STARTS PUSHING EAST LATE IN THE DAY AND ESPECIALLY IN THE NIGHT WITH SOUTHWEST FLOW ALOFT DEVELOPING OVER THE AREA. THIS RIDGE PLUS VERY DRY/WELL MIXED AIR MASS ALOFT WILL KEEP CONDITIONS DRY...DESPITE THE FACT AN UPPER JET APPROACHES THE WESTERN PORTIONS OF THE AREA LATE IN THE NIGHT. SHOULD BE WARMER...QUESTION IS HOW MUCH WARMER. NAM CONTINUES TO BE THE MOST AGGRESSIVE WITH THIS. WIND FIELD AND CONSENSUS OF 850 MB TEMPERATURES SUPPORT GOING COOLER. THIS IS CLOSE TO WHAT CURRENT FORECAST HAS IN THERE AND ONLY MADE SLIGHT ADJUSTMENTS. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 300 AM MDT THU SEP 19 2013 A SHORTWAVE TROUGH WILL QUICKLY MOVE THROUGH SUNDAY NIGHT. THE STRONGEST FORCING WILL BE NORTH OF THE FORECAST AREA ACROSS NEBRASKA WHERE GFS ENSEMBLE MEAN QPF VALUES ARE HIGHEST. ISOLATED TO SCATTERED CONVECTION SHOULD IMPACT THE WESTERN PORTION OF THE FORECAST AREA BY SUNDAY EVENING AND THEN OVERSPREAD THE REST OF THE AREA OVERNIGHT. THE GREATEST RAIN CHANCES AND POTENTIAL FOR THE HIGHEST RAINFALL AMOUNTS WILL BE OVER ROUGHLY THE NORTHEASTERN HALF OF THE FORECAST AREA. SLIGHTLY COOLER TEMPERATURES WILL ARRIVE BEHIND THIS SHORTWAVE AND ASSOCIATED COLD FRONT ON MONDAY BUT COLD AIR ADVECTION IN THE WAKE OF THIS SYSTEM IS BRIEF AND INSIGNIFICANT. STRONG EAST TO WEST ORIENTED MID/UPPER FLOW WILL BE SITUATED OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS ON TUESDAY. BY MID WEEK A LARGE TROUGH EVOLVES OVER THE WESTERN CONUS. MODELS DIFFER ON HOW THIS TROUGH WILL EVOLVE BY MID WEEK WITH GFS AND ECMWF DIFFERING ON THE POSITION OF CLOSED UPPER LOW...MEANWHILE GFS ENSEMBLE MEAN DEPICTS A MORE OPEN/PROGRESSIVE TROUGH. IN EITHER SCENARIO...SIGNIFICANT IMPACTS TO OUR AREA ARE NOT EXPECTED THROUGH THE END OF THE EXTENDED PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1154 PM MDT WED SEP 18 2013 A FEW THUNDERSTORMS HAVE DEVELOPED ALONG THE PRE-FRONTAL TROUGH MOVING ACROSS THE CENTRAL HIGH PLAINS REGION TONIGHT. A FEW STORMS ARE MOVING NORTHEASTWARD IN THE VICINITY OF MCK AND GLD AND ARE EXPECTED TO BE PRESENT THROUGH ABOUT 09Z. AFTER 09Z...STORMS ARE EXPECTED TO DIMINISH AND MOVE OUT OF THE REGION. VFR CONDITIONS ARE EXPECTED THROUGH THE ENTIRE TAF PERIOD AT BOTH MCK AND GLD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM..BRB LONG TERM...BULLER AVIATION...LOCKHART
AREA FORECAST DISCUSSION
NWS JACKSON KY
217 AM EDT THU SEP 19 2013 .UPDATE... ISSUED AT 217 AM EDT THU SEP 19 2013 HAVE SENT A MINOR UPDATE INCORPORATING RECENT OBSERVATIONS. UPDATE ISSUED AT 1030 PM EDT WED SEP 18 2013 FRESHENED UP THE SKY COVER AND HOURLY TEMPERATURES AND DEW POINTS TO ACCOUNT FOR THE LATEST TRENDS. SOME PARTIAL CLEARING WILL WORK IN FROM THE WEST...HOWEVER BELIEVE THAT LOW CLOUDS WILL FILL BACK IN DURING THE OVERNIGHT WITH HIGH MOISTURE IN THE 1000-850 MB LAYER LINGERING. LEFT THE POPS AS IS...ALTHOUGH THE LATEST HRRR HAS BACKED OFF ON THE UPTICK IN CONVECTION TOWARDS DAWN FOR THE NORTHEASTERN PORTION OF THE AREA. UPDATE ISSUED AT 807 PM EDT WED SEP 18 2013 A FEW SHOWERS WILL WIND DOWN ACROSS NORTHEASTERN KENTUCKY IN THE NEXT HOUR. THE LATEST SHORT RANGE MODELS SHOW A LULL IN THE ACTIVITY THROUGH THE OVERNIGHT...BEFORE AN UPTICK OCCURS TOWARDS DAWN IN THE NORTHEASTERN HALF OF THE AREA...AS A WEAK SHORT WAVE TROUGH MOVES SOUTHEAST ACROSS OHIO VALLEY. HAVE BUMPED UP THE POPS A BIT CONSIDERING THE DECENT MODEL AGREEMENT. ALSO ADDED SOME PATCHY FOG AND MADE THE VALLEY TEMPERATURES A BIT MORE UNIFORM WITH ALL OF THE CLOUD COVER AND STEADY DEW POINTS IN THE LOW 60S. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 307 PM EDT WED SEP 18 2013 THE MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE MAJOR UPPER AIR FEATURES...HOWEVER THERE IS QUITE A BIT OF DIFFERENCE IN HOW THEY HANDLE THE PRECIPITATION FORECASTS OVER THE NEXT 36 HOURS. A WARM FRONT HAS MOVED TO THE NORTHEAST OF THE AREA AND EASTERN KENTUCKY IS NOW IN THE WARM SECTOR WITH A SURFACE HIGH OFF THE EAST COAST AND A SURFACE RIDGE EXTENDING ACROSS EASTERN KENTUCKY. A COLD FRONT IS OVER THE HEARTLAND AND WILL BE APPROACHING THE AREA...HOWEVER WILL NOT MOVE INTO EASTERN KENTUCKY UNTIL SATURDAY. THIS ALLOWS FOR THE GULF TO BE OPENED UP AND THERE WILL BE SOME FAIRLY WARM...MOIST AND CONDITIONALLY UNSTABLE AIR OVER THE AREA. THE MODELS DIFFER AS TO WHEN WEAK LITTLE PERTURBATIONS WILL BE ABLE TO KICK OFF ANY CONVECTIVE ACTIVITY. FROM EXPERIENCE...EXPECT THAT THERE WILL BE AN AFTERNOON AND EVENING MAXIMUM OF CONVECTIVE ACTIVITY...HOWEVER THERE MAY BE SOME UNEXPECTED LITTLE POP-UPS DURING THE OFF HOURS. THE MODEL BLEND HANDLED THE TEMPERATURES VERY WELL AND JUST MADE SOME MINOR TWEAKS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 307 PM EDT WED SEP 18 2013 ON FRIDAY A COLD FRONT EXTENDING FROM THE WESTERN GREAT LAKES INTO THE MID MS VALLEY WILL BE MOVING EAST AS AN UPPER LEVEL SHORT WAVE TROUGH PUSHES EAST THROUGH THE PLAINS. THE UPPER TROUGH AND SURFACE COLD FRONT WILL MOVE EAST WITH RAIN CHANCES INCREASING ACROSS THE AREA AS WE HEAD INTO THE WEEKEND. MOST RECENT RUNS OF THE VARIOUS OPERATIONAL MODELS ARE POINTING TOWARDS SLOW FRONTAL MOVEMENT WITH THE FRONT MOVING ACROSS THE AREA ON SATURDAY...AND LIKELY STALLING OUT. THE LATEST WPC GUIDANCE IS ALSO FAVORING THIS IDEA WITH THE FRONT APPROACHING THE FORECAST AREA AT 12Z SATURDAY. OF THE OPERATIONAL MODELS THE 12Z NAM IS THE OUTLIER...AS IT PUSHES THE UPPER TROUGH AND SURFACE FRONT THROUGH MUCH QUICKER...WITH THE FRONT EAST OF KY BY 15Z SATURDAY. WILL LEAN AWAY FROM THE NAM FORECAST AS ALL THE OTHER MODELS ARE MUCH SLOWER. THE 12Z GFS SHOWS THE SOUTHERN PART OF THE UPPER TROF SLOWING DOWN WITH AN UPPER LOW CLOSING OFF IN THE VICINITY OF EASTERN KY BY SUNDAY. THE 00Z ECMWF AND 12Z GEM ALSO SUPPORT THE IDEA OF SLOW MOVEMENT WITH AN UPPER LOW FORMING OVER THE UPPER SOUTH INTO THE TN VALLEY. OVERALL...MODELS AND WPC GUIDANCE POINT TOWARDS WET CONDITIONS OVER THE WEEKEND. THE LATEST BLENDED LOAD ALSO SUPPORTS THIS. EXACTLY HOW LONG THE SLOW MOVING UPPER LOW AND ASSOCIATED SURFACE LOW LINGER NEARBY AND CONTINUE TO AFFECT OUR WEATHER IS STILL UNCERTAIN. THE 00Z ECMWF POINTS TOWARDS RAIN CHANCES LINGERING INTO THE MIDDLE OF NEXT WEEK...WHILE THE 12Z GFS IS DRIER...WITH LESS OF A CHANCE OF RAIN AFTER MONDAY. WHILE THE STANDARD BLENDED LOAD RESULTED IN A CHANCE OF RAIN IN THE SOUTHEAST ON TUESDAY AND WEDNESDAY HAVE DECIDED TO FOLLOW THE CONSENSUS OF NEIGHBORING WFOS AND WILL GO WITH A DRY FORECAST ON TUESDAY AND WEDNESDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 217 AM EDT THU SEP 19 2013 CONDITIONS STARTED OUT MOSTLY VFR. HOWEVER...DETERIORATION IS EXPECTED OVERNIGHT. IFR IS FORECAST FOR MOST LOCATIONS DUE TO LIGHT FOG. HOWEVER...CONFIDENCE IS LOW CONCERNING HOW FAR THE VISIBILITY DROPS. FOG WILL DISSIPATE ON THURSDAY MORNING...BUT MVFR CEILINGS ARE EXPECTED TO PERSIST IN MOST AREA UNTIL EARLY AFTERNOON...BEFORE SCATTERING OUT AND LEAVING VFR TO FINISH THE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HAL SHORT TERM...JJ LONG TERM...SBH AVIATION...HAL
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1153 PM CDT Wed Sep 18 2013 .UPDATE... ISSUED AT 1153 PM CDT WED SEP 18 2013 The aviation section has been updated for the 06Z TAF issuance. && .SHORT TERM /Tonight through Friday night/... ISSUED AT 230 PM CDT WED SEP 18 2013 The showers and isolated thunderstorms that occurred this morning have all but dissipated by mid afternoon. Partial clearing will continue to spread slowly east. The trend toward low and mid level drying is indicated by RAP and nam model soundings. This drying appears to be in response to a gradual rebuilding of the 500 mb ridge that was flattened by a weak impulse this morning. Through Thursday...the mid level ridge will continue to slowly build over our region. This should continue to suppress most convection over the Lower Ohio and Mid Mississippi Valleys. Will keep slight chance pops during the peak heating hours from roughly 18z to 00z to account for isolated diurnally driven storms. A rather strong cold front will approach from the northwest on Thursday night...reaching southern Illinois and southeast Missouri on Friday. The front will continue moving southeast across western Kentucky and southwest Indiana on Friday evening. The 09z sref timing looks reasonable. A deepening upper trough will enhance lift along the frontal zone...and deep layer moisture will be high for this time of year /sref precip water values about 1.9 inches/. Looks like the first widespread significant rainfall of the month will occur. Storm total qpf should be at least one half inch...with some 1 inch amounts likely in heavier convection. Severe weather potential will depend on how much sunshine and diurnal heating takes place ahead of the front. Isolated severe convection is currently forecast by SPC /see day 3 outlook/. South to southwest low level flow will keep unseasonably warm and humid conditions in place through Friday. The nam continues to have problems with too much moisture in the model...as shown in its high pops and abundant cloudiness. The warmer gfs mos highs look better for Thursday. .LONG TERM /Saturday through Wednesday/... ISSUED AT 230 PM CDT WED SEP 18 2013 Main issue in the extended looks to be with how quickly an upper level trof will move east out of the region over the weekend. Models seem to be trending toward a less progressive solution in this respect. Both the operational GFS and ECMWF suggest showers will linger into Saturday along and south of the Ohio River, east of the H50 trof axis. Will bump up precip chances on Sat into the 40 to 50 percent range over much of the Pennyrile region of western KY. Otherwise, the most noticeable change over the weekend will be another transition to much cooler and less humid conditions. Highs both Saturday and Sunday will likely stay down in the 70s, with lows Sat night mostly in the 50 to 55 degree range. As we head into next week, it now appears as though an Omega Blocking pattern will become established along the MS River Valley. This should keep things quite dry across our region, with sunny, warm afternoons and cool nights. Temperatures will warm a touch each day, and most locations will likely be back into the middle 80s by Wednesday afternoon. Humidity levels should stay low though. && .AVIATION... ISSUED AT 1153 PM CDT WED SEP 18 2013 Some mid-level ceilings and light showers over central Illinois may try to clip KEVV late tonight. Elected not to mention any precipitation as it would likely be of little impact. Still looking at 5kts of a south wind overnight at all sites, so will not mention fog. The only issue may be at KOWB where they are nearly saturated as of 04Z. Added in a minor SSW gust in most locations for Thursday, due to a decent pressure gradient and decent mixing expected. Still cannot rule out some isolated to scattered diurnal convection, but will not mention anything in the forecast at this time. Even if there is development, the coverage would likely be too sparse to mention. Light south winds and mid clouds can be expected throughout the area Thursday evening. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$ UPDATE...DRS SHORT TERM...MY LONG TERM...GM AVIATION...DRS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1208 AM EDT THU SEP 19 2013 LATEST UPDATE... AVIATION .SYNOPSIS... ISSUED AT 148 PM EDT WED SEP 18 2013 A WARM FRONT WILL PUSH NORTHWARD THROUGH LOWER MICHIGAN TONIGHT LEADING TO SOME SHOWERS AND THUNDERSTORMS. SOUTHWEST WINDS WILL INCREASE THURSDAY ALLOWING FOR AND UNSEASONABLY WARM DAY. MOISTURE FROM THE GULF OF MEXICO WILL STREAM INTO THE AREA THURSDAY NIGHT AND EARLY FRIDAY AHEAD OF A COLD FRONT. AS THIS FRONT PUSHES THROUGH THE REGION FRIDAY...A PERIOD OF SHOWERS AND THUNDERSTORMS CAN BE EXPECTED. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 148 PM EDT WED SEP 18 2013 THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE TIMING AND STRENGTH OF THE CONVECTION. STORMS IN NW ILLINOIS ARE SHOWN TO WEAKEN AS THEY HEAD TOWARD CHICAGO THIS AFTERNOON. HRRR SHOWS CONVECTION REDEVELOPING OVER LAKE MI LATER TONIGHT AND MOVING INTO THE HOLLAND TO MUSKEGON REGION. THIS MAKES SENSE WITH A STRENGTHENING LOW LEVEL JET ACCOMPANYING THE WARM FRONT THAT FEATURES ELEVATED INSTABILITY. NOT ALL MODELS HAVE THIS...BUT THE HRRR TENDS TO HANDLE THE CONVECTION BETTER THAN MOST. WILL DECREASE POPS INLAND TONIGHT...BUT CLOSER TO LAKE MI WILL KEEP THE LIKELY VALUES GOING. SEVERE WEATHER IS NOT FORECASTED...BUT PERHAPS A HEAVY RAIN THREAT MAY EXIST. A LULL IN THE CONVECTION IS EXPECTED THU AS NO FOCUSING MECHANISM IS SHOWN. IT WILL BE A WARM AND INCREASINGLY HUMID. IT DOES BECOME RATHER UNSTABLE...SO WILL HOLD ONTO A LOW POP FOR STORMS. I RAISED POPS FOR FRIDAY. WITH PWAT VALUES APPROACHING 2 INCHES AND A FRONT PRESSING IN ALONG WITH LIFT...IT SHOULD BE RATHER WET AT TIMES. MODELS HAVE TRENDED SOMEWHAT FASTER WITH THE FRONT...SO WE MAY BE ABLE TO START DRYING THINGS OUT FROM THE WEST BEFORE THE END OF THE DAY. WILL WAIT TO SEE IF THIS TREND PERSISTS BEFORE CHANGING FRIDAYS FORECAST. I DID LOWER POPS FOR FRIDAY NIGHT BECAUSE OF THIS. AS FOR SEVERE WEATHER...THE STRONGER DEEP LAYER SHEAR IS SHOWN TO LAG BEHIND THE COLD FRONT...SO SOMEWHAT OF A LIMITED RISK. STILL WITH BETTER INSTABILITY DEVELOPING AND INCREASING WIND FIELDS ALONG WITH A LOW LEVEL JET MOVING IN AND STRENGTHENING...A RISK STILL EXISTS. WILL NEED TO MONITOR TRENDS CLOSELY IN THE COMING DAYS. .LONG TERM...(SATURDAY THROUGH WEDNESDAY) ISSUED AT 243 PM EDT WED SEP 18 2013 AN UNEVENTFUL PERIOD IS EXCEPTED FOR THIS WEEKEND AND INTO THE FIRST HALF OF NEXT WEEK. HIGH PRESSURE OVER THE UPPER MIDWEST ON SATURDAY WILL SLOWLY MOVE OVER THE GREAT LAKES BY LATE IN THE WEEKEND. THIS HIGH WILL BE STALLED OVER THE AREA AS A STORM SYSTEM MOVES UP THE EAST COAST THROUGH THE FIRST HALF OF THE WORK WEEK. SO FAIR WEATHER SHOULD PREVAIL. LOWERED TEMPS A BIT FOR SATURDAY AND SUNDAY AS WE WILL BE UNDER A THERMAL TROUGH . BOTH DAYS SHOULD SEE HIGHS STAYING IN THE 60S. WE SHOULD SEE A WARM UP INTO THE WORK WEEK. HOWEVER LOW LEVEL FLOW WILL BE FROM THE EAST OR SOUTHEAST...SO ANY MODERATION OF TEMPS WILL BE GENTLE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1159 PM EDT WED SEP 18 2013 THE POTENTIAL AND TIMING OF THUNDERSTORMS CONTINUES TO BE PROBLEMATIC SO THIS IS A LOW CONFIDENCE FCST. TSTM COMPLEXES HAVE DEVELOPED TO OUR SOUTH AND OUR NORTH ALTHOUGH NOTHING YET IN BETWEEN THE TWO. WILL NOT MAKE MUCH CHANGE FROM THE PREVIOUS TAFS... KEEPING VCTS OVERNIGHT INTO THURSDAY MORNING BUT THIS IS QUESTIONABLE. A LULL IN CONVECTIVE POTENTIAL IS STILL EXPECTED THURSDAY AFTERNOON AND EVENING BEFORE THE NEXT DECENT CHANCE OF TSTMS WILL COME THURSDAY NIGHT AFTER 06Z. OUTSIDE OF ANY TSTMS...VFR IS EXPECTED OVER THE NEXT 24 HOURS. HOWVER THERE COULD BE SOME LIGHT FOG/HAZE DEVELOPING LATE TONIGHT AND THURSDAY AS HIGHER DEW POINTS COME IT...POSSIBLY GIVING MVFR VSBYS IN SPOTS. && .MARINE... ISSUED AT 148 PM EDT WED SEP 18 2013 WINDS ARE FORECASTED TO BE STRONGER THU INTO THU NIGHT. MAY NEED SMALL CRAFT AND BEACH HAZARDS TO COVER THIS. UNTIL THEN THE SOUTHERLY FLOW WILL KEEP WAVES UP TO AROUND 2 TO 4 FEET...ESPECIALLY OFF OF LITTLE AND BIG SABLE POINTS. && .HYDROLOGY... ISSUED AT 148 PM EDT WED SEP 18 2013 LOCALIZED HEAVY RAIN WILL BE POSSIBLE WITH THE STORMS TONIGHT AS A LOW LEVEL JET MOVES IN PWAT VALUES CLIMB TO OVER 1.5 INCHES. CORFIDI VECTORS SUGGESTS A LOCALIZED HEAVY RAIN THREAT MAY EXIST. CURRENTLY IT APPEARS THAT AREAS ALONG THE LAKESHORE STAND THE HIGHEST CHANCE FOR THE STORMS. A MORE WIDESPREAD ROUND OF STORMS IS FORECASTED FOR THU NIGHT INTO FRI. PWAT VALUES LIKELY TO CLIMB ABOVE 1.75 INCHES WITH ANOTHER LOW LEVEL JET PUSHING THROUGH. CORFIDI VECTORS ALSO SUGGEST A HEAVY RAIN THREAT. HOW MUCH RAIN FALLS WILL LIKELY DEPEND ON HOW EFFICIENT THE RAIN BECOMES AND HOW THE CONVECTION EVOLVES. SUSPECT LOCALLY MORE THAN 2 INCHES WILL FALL BY FRI NIGHT. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS...MJS SHORT TERM...MJS LONG TERM...JK AVIATION...MEADE HYDROLOGY...MJS MARINE...MJS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
318 AM MDT THU SEP 19 2013 .SHORT TERM...VALID FOR TDY AND FRI... UPPER TROUGH CROSSING THE REGION TONIGHT WILL CONTINUE TO EXERT ITS INFLUENCE OVER OUR FORECAST AREA WELL INTO THURSDAY... ESPECIALLY IN THE NORTHEAST ZONES. AS SUCH...SOME CHANGES HAVE BEEN MADE FOR TODAYS FORECAST. EARLY THIS MORNING...THE MAIN 500MB COLD POOL WAS SITUATED OVER SOUTHWEST MONTANA. THERE WAS ANOTHER MID LEVEL COLD POOL OVER NORTH CENTRAL MONTANA AS WELL WITH AN ASSOCIATED FRONT PUSHING EAST/SOUTHEAST ACROSS MONTANA. THIS FEATURE WILL SLIP DOWN THROUGH OUR ZONES BY 6AM. THERE IS A CONSISTENT EFFORT FROM THE MODELS TO BRING IN A LOW CLOUD DECK BEHIND THIS FEATURE...THICKEST ACROSS CUSTER AND FALLON COUNTIES. WHILE SOUNDINGS AND HRRR DATA PARTIALLY BREAK MILES CITY OUT OF THIS IN THE AFTERNOON...THEY SUGGEST BAKER AND FALLON COUNTY WILL PERSIST UNDER OVERCAST CONDITIONS AS LONG AS 6PM. THIS SCENARIO IS A NOTORIOUS FORECAST BUSTER FOR BAKER. UNLESS I SEE SOMETHING AT THE LAST MOMENT SUGGESTING OTHERWISE...I WILL PLAN TO LOWER TEMPERATURES QUITE A BIT IN THIS AREA. ANOTHER CHANGE...THOUGH MINOR...WAS IN REGARD TO A TROWEL FEATURE ON THE BACKSIDE OF THE TROUGH. THIS IS CURRENTLY GENERATING SOME PRECIPITATION ALONG THE FRONT RANGE AND NORTHWEST MOUNTAINS. CROSS SECTIONS SHOW SOME MODEST LIFT AND MOISTURE AS IT WORKS OVER OUR FORECAST AREA THIS MORNING. IT WILL HAVE TO BATTLE A BRISK DOWNSLOPE WIND...SO VIRGA AND SPRINKLES MAY BE THE MAIN OUTCOME. HOWEVER...I HAVE SPREAD SOME LOW POPS BACK TO THE WEST AS WELL AS A LITTLE FURTHER SOUTH INTO UPSLOPE AREAS NEAR THE BIG HORNS FOR THE FIRST HALF OF THE DAY. THE TROUGH AXIS WILL BE JUST EAST OF THE MONTANA/DAKOTA BORDER BY EVENING. SO WE SHOULD SEE DECREASING CLOUDS AND WIND. LOWS MAY DIP TO AROUND OR JUST BELOW AVERAGE FOR THIS TIME OF YEAR...MAKING IT ONE OF THE OVERALL COOLEST WE HAVE HAD SO FAR THIS SEPTEMBER. RIDGE BUILDS IN QUICKLY FOR TOMORROW WHICH WILL RESULT IN A NICE BUMP IN THE MERCURY. BT .LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED... EXTENDED MODELS IN GOOD AGREEMENT FOR THIS WEEKEND GOING INTO EARLY NEXT WEEK BUT DIVERGE WITH A LARGE SYSTEM ACROSS THE WESTERN STATES BY MID NEXT WEEK. RIDGE AND ITS AXIS SHIFT EAST SATURDAY AS AN UPPER LOW AND TROUGH MOVE ONTO THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA COAST. SOUTHWEST FLOW ALOFT WILL PREVAIL ALONG WITH ABOVE NORMAL TEMPERATURES AND A SLIGHT SHOWER/THUNDERSTORM CHANCE. THE TROUGH ALONG WITH A COLD FRONT MOVE THROUGH THE FORECAST AREA LATE SATURDAY NIGHT INTO SUNDAY MORNING BRINGING BETTER CHANCES FOR SHOWERS WITH COOLER AND MORE NORMAL TEMPERATURES FOR SUNDAY. FAST ZONAL FLOW ALOFT LOOKS IN STORE FOR MONDAY AND TUESDAY WITH MAINLY A DOWNSLOPE SURFACE FLOW KEEPING CONDITIONS DRY FOR THE LOWER ELEVATIONS WITH SHOWERS FOR THE MOUNTAINS. BY LATE TUESDAY INTO WEDNESDAY...AN UPPER LOW TAKES SHAPE ACROSS THE PACIFIC NORTHWEST. MODELS DIVERGE GREATLY FROM THAT POINT ONWARD. THE GFS TAKES THE LOW SOUTH INTO THE GREAT BASIN AREA WEDNESDAY AND THURSDAY WHILE THE ECMWF EJECTS THE LOW NORTHEAST ACROSS MONTANA BUT STILL KEEPING A TROUGH ACROSS THE CENTRAL AND NORTHERN ROCKIES. EITHER SCENARIO WILL BRING INCREASING CHANCES FOR PRECIP TO THE FORECAST AREA. HOWEVER...LOCATION AND AMOUNTS OF PRECIP ALONG WITH TEMPEATURES VARY QUITE A BIT DEPENDING ON MODEL. WILL KEEP CHANCE POPS FOR MID NEXT WEEK WITH HIGHEST CHANCES FOR THE MOUNTAINS ALONG WITH A TREND TO COOLER TEMPERATURES. HOOLEY && .AVIATION... EXPECT PARTLY TO MOSTLY CLOUDY SKIES TODAY WITH VFR CONDITIONS PREVAILING. THE EXCEPTION WILL BE ISOLATED TO SCATTERED SHOWERS POSSIBLE ALONG AND NORTH OF A KLVM- KBIL-KBHK LINE TODAY WHICH WILL RESULT IN POSSIBLE MVFR CONDITIONS AT TIMES. MVFR TO IFR CONDITIONS WILL ALSO BE POSSIBLE AT TIMES DUE TO LOW CEILINGS FROM KMLS EASTWARD. GUSTY NORTHWEST WINDS WILL BE LIKELY FROM KBIL EASTWARD BUT ESPECIALLY TOWARD KMLS TO THE DAKOTA BORDERS. HOOLEY && .PRELIMINARY POINT TEMP/POPS... TDY FRI SAT SUN MON TUE WED ------------------------------------------------------- BIL 065 043/077 049/084 053/068 048/071 050/071 048/062 1/B 00/U 00/U 22/T 11/B 02/T 22/W LVM 064 035/078 043/083 046/065 042/068 045/068 045/054 0/B 00/U 00/U 22/T 11/B 12/T 23/W HDN 066 038/079 045/086 051/072 046/073 049/074 048/065 2/W 00/U 00/U 12/T 21/B 01/B 12/W MLS 059 042/075 048/084 054/073 050/075 052/074 050/068 2/W 00/U 00/U 22/T 21/U 11/B 12/W 4BQ 062 038/075 045/084 053/075 047/074 049/075 047/068 1/B 00/U 00/U 12/T 21/U 11/U 12/W BHK 056 037/072 044/080 050/075 047/073 048/074 047/069 2/W 00/U 00/U 12/T 21/U 11/U 12/W SHR 063 036/076 046/084 050/070 044/071 047/072 045/064 1/B 00/U 00/U 12/T 30/U 01/U 12/W && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
251 AM CDT THU SEP 19 2013 .DISCUSSION... GLANCE AT REGIONAL RADAR ALREADY SHOWING LINE OF CONVECTION FIRING ALONG INTENSE SFC BAROCLINIC ZONE EXTENDING FROM ABOUT NRN MN TO NWRN KS. BNDRY IN ASSOCIATION WITH UPPER SHORTWAVE TROF MIGRATING ACROSS THE NRN PLAINS. AGEOSTROPHIC LIFT JUST AHEAD OF RELATIVELY DEEP FRONTOGENESIS BNDRY IS QUITE STOUT...PER RUC13. ALSO...STRONG UPPER LEVEL DIVG ASSOCIATE WITH RRQ OF JET MAX ALOFT CONTRIBUTING TO ENHANCEMENT OF SYNOPTIC LIFT AS WELL. SHORT TERM ISSUE IS TIMING THE FRONTAL PASSAGE/PCPN THRU THE CWA. REGIONAL RADAR WAS SHOWING AN OUTFLOW BNDRY ASSOCIATED WITH CLUSTER OF STORMS IN WRN NEB WAS QUICKLY PUSHING EAST...AND WILL PROBABLY REACH THE CWA IN THE NEXT COUPLE HOURS. AT ANY RATE...SFC WIND PROGS VIA TIME-SERIES INDICATE LEADING EDGE OF THE TRUE FRONT REACHING KOFK BY LATE MORNING...THEN EARLY AFTN AT KLNK AND KOMA...THUS APPROXIMATE TIME FRAME FOR FOR EXPECTED CONVECTION. MEANWHILE... PERSISTENT MOISTURE ADV INTO THE REGION THE LAST 24 HRS HAS CULMINATED IN A MOISTURE RICH ENVIRONMENT AS SEE BY PWS VALUES RANGING ANYWHERE FROM 160%-220% ABOVE NORM AHEAD OF THE FRONT. AT THIS POINT SUSPECT THAT PCPN INTENSITY WILL INCREASE THIS AFTN OVER SRN CWA WHERE THE RUC13 IS SHOWING PRECIP EFFICIENCY/WARM CLOUD DEPTH PEAKS. IMPROVING CONDITIONS THEN TONIGHT AS STABLE AIRMASS ENVELOPS THE REGION. IN CASE OF LINGERING PCPN ACTIVITY...WILL MAINTAIN TOKEN EVENING POPS SOUTH. EXCELLENT WEATHER ON TAP THIS WEEKEND IN RESPONSE TO UPPER RIDGE BUILDING OVER THE PLAINS. NEXT ROUND OF PCPN COMES SUNDAY NIGHT/MONDAY WHEN NEXT POTENT SHORTWAVE TROF EXITS THE ROCKIES AND SWEEPS ANOTHER COLD FRONT INTO THE CNTRL PLAINS. WITH GFS AND ECM IN AGREEMENT DECENT LLVL MOISTURE FEED PRECEDING THE FRONT...GENEROUS RAINFALL AMOUNTS WILL ONCE AGAIN BE POSSIBLE. DEE && .AVIATION...06Z TAFS FOR KOFK...KOMA AND KLNK. A COLD FRONT IS STILL ON TRACK TO CROSS TAF SITES THURSDAY WITH SCATTERED SHOWERS AND THUNDERSTORMS MOSTLY ALONG OR BEHIND FRONT. FIRST ROUND OF CONVECTION OVER WRN NEBR COULD MOVE ACROSS KOFK VICINITY THURSDAY MORNING AND FORECAST WILL REFLECT THIS. ALTHOUGH SOME OF THIS ACTIVITY COULD IMPACT KLNK AND KLNK...TSTMS WERE NOT MENTIONED AT THOSE SITES UNTIL AFTERNOON WHEN ADDITIONAL DEVELOPMENT IS EXPECTED AND CHANCES APPEARED HIGHER. THUS PROB30 GROUPS IN 00Z FORECAST WERE UPGRADED TO TEMPO GROUPS AT BOTH KLNK AND KOMA. SHOWERS/ISOLD TSTMS COULD LINGER INTO EARLY THURSDAY EVENING BEFORE MOVING TO THE EAST. CHERMOK && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ 99/99
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
1111 PM MDT WED SEP 18 2013 .AVIATION... 06Z TAF CYCLE MTS OCCASIONALLY OBSCURED. ISOLD CONVECTION TO PERSIST AND MOVE GENLY NORTHEAST TO EAST OVER NRN AND CENTRAL NM THROUGH THE OVERNIGHT HOURS AS UPPER DISTURBANCE TRACKS EAST OVER THE REGION. LOCALIZED MVFR CIGS/VSBYS IN TSRA WILL BE POSSIBLE ALONG WITH SFC WND GUSTS TO 35KT. LOCAL MVFR CIGS POSSIBLE FROM THE CENTRAL MT CHAIN ACROSS THE EASTERN PLAINS AFT 08Z TO AROUND 15Z THURSDAY. SFC FRONT TO APPROACH FAR NE NM BY 15Z THURSDAY WITH SCT CONVECTION DVLPG THEREAFTER FROM THE CENTRAL MT CHAIN TO THE TX BORDER. && .PREV DISCUSSION...256 PM MDT WED SEP 18 2013... ANOTHER ACTIVE WX SCENARIO SHAPING UP OVER THE REGION FOR REMAINDER OF TODAY THRU THURSDAY. CIRA LAYERED TOTAL PW PRODUCT SHOWS ABUNDANT LOW/MID LEVEL MOISTURE ACROSS THE REGION WITH VERY DRY CONDITIONS ALOFT. VALUES ARE ON THE ORDER OF 130-160 PCT OF NORMAL. A THIN 30- 50 KT UPPER JET AXIS OVER NM AS SEEN ON THE LATEST AMDAR DATA IS INTERACTING WITH THE LOW LEVEL MOISTURE AND INSTABILITY TO PRODUCE A WELL DEFINED BAND OF THUNDERSTORMS OVER WESTERN AND NORTHERN NM. STEERING FLOWS ARE STRONG TODAY HOWEVER THE SHEAR AXIS IS ORIENTED IN THE DRXN OF STORM MOTION SO MORE LOCALLY HEAVY RAINFALL ON TAP. LATEST HRRR SHOWS THIS AREA OF SHOWERS AND STORMS PROPAGATING EVER SO SLOWLY EAST THIS EVENING INTO THE RIO GRANDE VALLEY AND NEARBY HIGH TERRAIN. HAVE RAISED POPS TO HIGH CHANCE AND LIKELY FOR CENTRAL NM. EVEN MORE ACTIVE CONDITIONS WILL TAKE SHAPE INTO THURSDAY NIGHT BUT MORE INTO THE EASTERN PLAINS. A LARGE UPPER TROUGH OVER THE PACIFIC NW WILL SLIDE EAST INTO THE GREAT PLAINS AND HELP DRIVE A SURFACE BACK DOOR FRONTAL BOUNDARY INTO NM. MEANWHILE...A VERY WELL DEFINED UPPER WAVE EMBEDDED ON THE BACK SIDE OF THE LARGE SCALE WAVE WILL SLIDE OVER NORTHERN NM AND HELP LIFT FOCUS OVER FRONT. CURRENT QPF VALUES ARE POTENTIALLY TOO LOW FOR THIS EVENT ACROSS THE EAST WHERE SUBSTANTIALLY MOISTURE REMAINS IN PLACE. FLOODING IS NOT EXPECTED HOWEVER SOME LOCALIZED IMPACTS ARE LIKELY IF THE RAIN FALLS OVER THE WRONG SPOT. ALSO RAISED POPS FOR THE EASTERN PLAINS THURSDAY NIGHT TO LIKELY. TEMPS THROUGH THIS PERIOD WILL COOL BELOW NORMAL FOR MUCH OF THE REGION...ESPECIALLY THE EAST. MODELS DO INDICATE STRONGER WESTERLIES AND DRIER AIR SHIFTING EAST INTO THE STATE FRIDAY THRU SUNDAY HOWEVER STRONG MOISTURE RECYCLING PROCESSES WILL STILL BE AT PLAY. LOW CLOUDS AND FOG ARE POSSIBLE ANY NIGHT ESPECIALLY IF SKIES CLEAR AND WINDS TAPER OFF. TEMPS WILL BE COOL OUT WEST WHERE MUCH DRIER DEWPOINTS WILL MOVE IN. THE EXTENDED PATTERN IS STILL HIGHLY UNCERTAIN SO MADE NO CHANGES. THE ECMWF PROGS A DEEP LARGE SCALE STATIONARY UPPER LOW OVER THE GREAT BASIN WITH A RELATIVELY ABUNDANT MONSOONAL MOISTURE TAP OVER NM. THE GFS HAS AN EVEN DEEPER TIGHTLY WOUND COLD UPPER LOW DRIVING EAST ACROSS THE CENTRAL ROCKIES THRU MID WEEK. GUYER && .FIRE WEATHER... SCATTERED WETTING THUNDERSTORMS FOUND ACROSS WESTERN AND NORTHERN AREAS WILL TRANSITION EASTWARD THIS EVENING BEFORE DIMINISHING SOME. DRIER AIR WILL EVENTUALLY FILL IN FROM WEST TO EAST LATER TONIGHT AND WILL SET THE STAGE FOR A DRIER WESTERN AND CENTRAL AREAS ON THURSDAY. A BACK DOOR COLD FRONT IS STILL EXPECTED FOR THURSDAY WITH EASTERN AREAS OBSERVING THAT INFLUENCE. THIS INCLUDES WETTING SHOWERS AND THUNDERSTORMS WHICH WOULD FAVOR MOST OF THE EASTERN PLAINS THURSDAY AFTERNOON INTO THE OVERNIGHT. MIXING HEIGHTS WILL INCREASE ACROSS THE MAJORITY OF THE AREA ALTHOUGH TRANSPORT WINDS WILL COME DOWN MOST AREAS SO VENTILATION RATES WILL LOWER PRETTY MUCH AREAWIDE. THE BACK DOOR COLD FRONT WILL PUSH THROUGH THE CENTRAL MOUNTAINS THURSDAY NIGHT AND MOST LIKELY MAKE IT TO THE AZ STATE LINE BY FRIDAY MORNING. MIXING DURING FRIDAY AFTERNOON SHOULD SET UP A CONVERGENCE BOUNDARY NEAR THE CONTINENTAL DIVIDE AND MOST LIKELY PROVIDE A FOCUS FOR THUNDERSTORMS THERE. THE ATMOSPHERE COULD BE TOO STABLE FOR SIGNIFICANT SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS CENTRAL AND EASTERN AREAS DUE TO RESIDUAL IMPACTS FROM THE COLD FRONT. HUMIDITY VALUES WILL BE UNSEASONABLY HIGH FRIDAY AFTERNOON. TEMPERATURES WILL BE COOLER THAN NORMAL CENTRAL AND EASTERN AREAS WHILE BEING NEAR NORMAL WEST OF THE CONTINENTAL DIVIDE. VENTILATION RATES WILL BE LOWEST EXTENDING FROM ZONE 109 NORTHEASTWARD OVER THE MIDDLE RIO GRANDE VALLEY AND AREAS TO THE LEE OF THE SANGRE DE CRISTOS. THE NEXT PACIFIC TROUGH WILL PLUNGE INTO THE FAR WESTERN US SATURDAY AND CONTINUE TO TRAVERSE ACROSS THE INTERMOUNTAIN WEST ON SUNDAY. MOISTURE WILL TRY TO SEEP UP FROM MEXICO AHEAD OF THIS TROUGH SO LOOK FOR UNSETTLED WEATHER ACROSS THE WEST ON SATURDAY TRANSITIONING SOME EASTWARD ON SUNDAY. WETTING RAIN WOULD CERTAINLY BE POSSIBLE ALTHOUGH NOT AS WIDESPREAD AS THE PREVIOUS WEEK. HUMIDITY IS EXPECTED TO TREND UP ACROSS THE WEST ON SATURDAY WHILE LOWER ACROSS THE EAST. ON SUNDAY...HUMIDITY IS EXPECTED TO LOWER AREAWIDE ALTHOUGH THIS COULD CHANGE. VENTILATION WILL INCREASE DURING THE WEEKEND THANKS TO STRONGER WEST/SOUTHWEST TRANSPORT WIND. CONFIDENCE IS PRETTY GOOD THAT A PACIFIC TROUGH WILL IMPACT THE AREA BUT STILL NOT TOTALLY SURE ABOUT HOW MUCH MOISTURE WILL SEEP UP FROM THE SOUTH AND FEED THE TROUGH. SURFACE WIND SHOULD ALSO INCREASE DURING THE WEEKEND PERIOD. ANOTHER PACIFIC TROUGH IS EXPECTED TO AFFECT THE WESTERN US BY THE MIDDLE OF NEXT WEEK. THE LONG RANGE MODELS DIFFER SOMEWHAT IN THE EXTENSION SOUTHWARD OF THE TROUGH BUT EITHER WAY IMPACT POTENTIAL WOULD INCREASE BY MID NEXT WEEK. DEPENDING ON HOW THE TROUGH COMES IN...ADDITIONAL WETTING RAIN WOULD BE POSSIBLE. CONDITIONS FOLLOWING THE TROUGH PASSAGE COULD LEAD TO THE MOUNTAINS FIRST BIG FREEZE OF THE FALL SEASON SO WILL BE WATCHING THAT AS THAT WOULD BEGIN THE CURING PROCESS TO THE ABUNDANT FUELS THAT HAVE GREENED UP THIS SUMMER. 50 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
401 AM EDT THU SEP 19 2013 .SYNOPSIS... A SERIES OF UPPER LEVEL DISTURBANCES WILL RESULT IN A CHANCE OF SHOWERS AND THUNDERSTORMS TODAY INTO TONIGHT. SHOWERS AND THUNDERSTORMS WILL BECOME MORE WIDESPREAD FRIDAY AFTERNOON INTO FRIDAY NIGHT AS A COLD FRONT APPROACHES FROM THE WEST. SHOWERS AND A FEW THUNDERSTORMS WILL CONTINUE INTO SATURDAY BEFORE A DRIER AND COOLER AIRMASS SETTLES INTO THE REGION FOR THE FIRST PART OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A PERSISTENT MCV HAS BEEN PROGRESSING VERY SLOWLY SOUTHEAST ACROSS NORTHERN INDIANA THROUGH THE OVERNIGHT HOURS. SO FAR IT HAS NOT SHOWED TOO MAY SIGNS OF DISSIPATING OR EVEN WEAKENING AND THE LAST SEVERAL RUNS OF THE HRRR HAVE BEEN CONSISTENTLY TRYING TO PUSH IT SOUTHEAST INTO OUR AREA THROUGH MID MORNING. THE AIRMASS ACROSS OUR AREA IS MORE STABLE WITH THE INSTABILITY GRADIENT DROPPING OFF FAIRLY QUICKLY ACROSS EASTERN INDIANA INTO WESTERN OHIO. AS A RESULT..WOULD EXPECT THE BETTER CHANCE OF THUNDERSTORM MAINTENANCE TO WORK MORE TO THE SOUTH AND STAY WEST OF MOST OF OUR AREA THROUGH THE MORNING HOURS. HOWEVER...THE 850-300 MB MEAN WIND IS MORE WESTERLY ACROSS NORTHERN INDIANA...BECOMING SOUTHEASTERLY ACROSS OUR AREA. THIS WOULD SUGGEST A DECENT CHANCE THAT SOME OF THE SHOWER ACTIVITY WILL WORK ITS WAY INTO AT LEAST THE WESTERN HALF OF OUR FA OVER THE NEXT SEVERAL HOURS. MEANWHILE...ABUNDANT LOW LEVEL MOISTURE ACROSS OUR AREA HAS ALLOWED FOR SOME FAIRLY WIDESPREAD STRATUS DEVELOPMENT ACROSS ABOUT THE SOUTHEAST TWO THIRDS OF OUR FA. WITH THE LOW LEVELS REMAINING MIXY THROUGH DAYBREAK...WOULD NORMALLY NOT BE SURPRISED TO SEE THE STRATUS EXPAND A LITTLE MORE...BUT THE DEBRIS CLOUDS FROM THE MCV MAY MITIGATE THIS TO SOME DEGREE. EITHER WAY...THE COMBINATION OF THE DEBRIS CLOUDS AND STRATUS DECK SHOULD KEEP US MAINLY CLOUD THROUGH THE MORNING HOURS. THIS MAY ALSO HAVE AN IMPACT ON TEMPERATURES AND HOW WELL WE DESTABILIZE THROUGH THIS AFTERNOON. IN THE WESTERLY TO SOUTHWESTERLY LOW LEVEL WAA PATTERN...WOULD EXPECT TO SEE SOME DECENT EROSION/DISSIPATION OF THE LOWER CLOUDS THROUGH LATE MORNING/EARLY AFTERNOON WHICH SHOULD EVENTUALLY ALLOW FOR PARTLY SUNNY SKIES. WILL NUDGE DOWN HIGHS JUST A TAD...GENERALLY RANGING FROM UPPER 70S EAST TO LOWER 80S WEST. THIS WOULD STILL ALLOW US TO DESTABILIZE THROUGH THIS AFTERNOON WITH ML CAPES PUSHING UP CLOSE TO 1000 J/KG. AS A RESULT...WILL GO AHEAD AND ALLOW FOR SOME CHANCE POPS ACROSS MUCH OF THE AREA THROUGH THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... THE 00Z NAM/GFS AND CMC ARE ALL TRYING TO HINT AT SOME SORT OF CONTINUING PCPN OR REDEVELOPMENT TONIGHT SOMEWHERE ACROSS OUR AREA WHILE THE 00Z ECMWF IS DRY. IT DOES LOOK LIKE WE COULD BE ON THE EDGE OF A SOUTHWEST TO NORTHEAST ORIENTED 925-850 MB LOW LEVEL JET LATER TONIGHT AND THIS COULD SERVE AS A FOCUSING MECHANISM. AS A RESULT..WILL HANG ON TO SOME LOWER END POPS...BUT CONFIDENCE IS NOT ALL THAT HIGH. A COLD FRONT WILL MOVE ACROSS THE AREA FRIDAY NIGHT. AHEAD OF THIS...WE SHOULD WARM UP FAIRLY WELL THROUGH THE DAY WITH HIGHS PUSHING UP INTO THE LOW TO MID 80S. THIS WILL ALLOW US TO DESTABILIZE ONCE AGAIN WITH MLCAPES AGAIN UP CLOSE TO 1000 J/KG. THIS SHOULD LEAD TO SOME SCATTERED PRE FRONTAL SHOWERS AND THUNDERSTORMS THROUGH THE DAY. BETTER LOW LEVEL CONVERGENCE JUST AHEAD OF THE FRONT WILL PUSH INTO OUR NORTHWEST LATE FRIDAY AFTERNOON AND THEN PROGRESS SOUTHEAST ACROSS OUR AREA THROUGH FRIDAY EVENING. THIS WILL ALLOW FOR A MORE ORGANIZED LINE OF SHOWERS AND THUNDERSTORMS. DEEP LAYER SHEAR IS NOT TERRIBLY STRONG INITIALLY WITH THE PCPN FRIDAY AFTERNOON/FRIDAY EVENING...BUT THE 0-3 KM SHEAR VALUES DO PUSH UP INTO THE 25 TO 30 KNOT RANGE. THIS MAY BE ENOUGH TO SUPPORT SOME MARGINALLY SEVERE STORMS LATE FRIDAY AFTERNOON INTO FRIDAY EVENING....ESPECIALLY ACROSS OUR NORTHWEST. AS THE FRONT PUSHES OFF TO THE SOUTHEAST...EXPECT PCPN TO TAPER OFF FROM NORTHWEST TO SOUTHEAST DURING THE DAY ON SATURDAY. HIGH PRESSURE AND A COOLER AIRMASS WILL BUILD INTO THE AREA THROUGH THE LATER PART OF THE WEEKEND. HIGHS ON SATURDAY WILL BE IN THE 70-75 DEGREE RANGE WITH HIGHS ON SUNDAY IN THE UPPER 60S TO NEAR 70. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... ON MONDAY...HIGH PRESSURE WILL BUILD IN FROM THE NORTH. COULD SEE ENOUGH MOISTURE FROM THE LOW MOVING UP THE COAST TO PRODUCE ISOLATED SHOWERS IN THE EXTREME EAST. AFTER MONDAY...SURFACE HIGH PRESSURE EXTENDING INTO THE REGION FROM THE NE WILL BRING DRY WEATHER AND MILD TEMPERATURES. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... SLIGHTLY UNSETTLED WEATHER CONDITIONS WILL CONTINUE THROUGH THE NEXT SEVERAL DAYS. MOISTURE CONTINUES TO INCREASE OVER THE OHIO VALLEY...RESULTING IN INCREASING CLOUDS...AND SHOWERS. THE BIGGEST CONCERN THIS MORNING IS THE POTENTIAL FOR STRATUS DEVELOPMENT. THERE IS HIGH CONFIDENCE IN A THICKENING OF THE LOW- LEVEL MOISTURE OVERNIGHT...WITH UPSTREAM CONDITIONS ALREADY INDICATING MVFR CEILINGS ACROSS MUCH OF KENTUCKY AND IFR CIGS ACROSS MUCH OF THE EASTERN HALF OF OHIO. THESE CLOUDS ARE EXPECTED TO LOWER AS THEY OVERSPREAD THE TAF SITES. THIS WILL MAKE THE FOG FORECAST SOMEWHAT MORE DIFFICULT BECAUSE THE STRATUS SHOULD KEEP THE VSBYS FROM LOWERING TO LIFR MOST AREAS. BOTTOM LINE IS THAT A BLANKET OF IFR CONDITIONS ARE EXPECTED TO DEVELOP ACROSS THE ENTIRE FORECAST AREA OVER THE NEXT FEW HOURS. CEILINGS WILL BE SLOW TO LIFT ON THURSDAY...AS SHOWERS AND LARGE PATCHES OF LATE RAIN OVER SPREAD THE AREA AFTER 09Z ASSOCIATED WITH A SMALL THUNDERSTORM COMPLEX OVER NORTHERN INDIANA MOVING TOWARDS THE SOUTHEAST. WHILE THERE IS A RISK OF THUNDER AS THE PRECIPITATION MOVES IN THIS MORNING...IT IS NOT HIGH ENOUGH TO PUT INTO THE FORECAST AT THIS TIME. SHOWERS AND LOW CLOUDS WITH MVFR CONDITIONS ARE EXPECTED TO LAST INTO THE MID AFTERNOON HOURS. OUTLOOK...THUNDERSTORMS WILL BE POSSIBLE FROM FRIDAY AFTERNOON THROUGH SATURDAY MORNING. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...JGL NEAR TERM...JGL SHORT TERM...JGL LONG TERM...PARKER AVIATION...HATZOS/HAYDU
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
118 AM EDT THU SEP 19 2013 .SYNOPSIS... AN INCREASE IN MOISTURE AND A SERIES OF WEAK UPPER LEVEL DISTURBANCES WILL RESULT IN A CHANCE OF SHOWERS AND A FEW THUNDERSTORMS TO THE REGION TONIGHT AND THURSDAY. A BETTER CHANCE OF THUNDERSTORMS WILL DEVELOP FRIDAY AFTERNOON INTO FRIDAY NIGHT AS A COLD FRONT MOVES ACROSS THE AREA FROM THE NORTHWEST. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... THERE ARE CONCERNS ON BOTH SIDES OF THE CWA TONIGHT...REQUIRING A FEW CHANGES TO THE GRIDS. IN THE EASTERN CWA...A LARGE EXPANSE OF STRATUS HAS DEVELOPED. AS ADDITIONAL MOISTURE MOVES NORTH INTO THE CWA...THIS IS EXPECTED TO CONTINUE THROUGH THE NIGHT...WITH CEILINGS LOWERING. SKY GRIDS HAVE BEEN ADJUSTED...THOUGH IT WAS NOT QUITE POSSIBLE TO INCREASE TO 100 PERCENT WHEN MOST OF THE CWA STILL IS MOSTLY CLEAR...OR EVEN BROKEN ON THE EDGES OF THE STRATUS. HOWEVER...THE FAR EASTERN CWA SHOULD REMAIN CLOUDY THROUGH THE NIGHT. ATTENTION IS ALSO TURNING TO CONVECTION NEAR CHICAGO...WHICH SEVERAL RUNS OF THE HRRR AND RAP INDICATE WILL MAKE IT INTO THE NORTHWEST CWA BY THE EARLY MORNING HOURS. THERE IS A GRADIENT OF ELEVATED INSTABILITY THAT WILL SHIFT GRADUALLY EAST THROUGH THE NIGHT...ALLOWING A TRAJECTORY (IF THE CONVECTION HOLDS TOGETHER) THAT WOULD EVENTUALLY MOVE THROUGH INDIANA AND INTO THE ILN FORECAST AREA. POPS HAVE BEEN INCREASED IN THE NORTHWESTERN CWA WITH THUNDER INTRODUCED. TIMING THE CONVECTION OUT WOULD HAVE IT INTO THE MERCER/WAYNE COUNTY AREAS BY 07Z...AND FURTHER FORECAST UPDATES WILL BE NECESSARY IF THIS LOOKS MORE LIKELY TO OCCUR. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... ISENTROPIC LIFT DEVELOPS ACROSS THE AREA THURSDAY WITH WARM FRONT LIFTING NORTHEAST INTO THE GREAT LAKES. WILL CONTINUE CHANCE POPS WITH THE BEST THREAT ACRS THE NW WHERE MOST FAVORABLE INSTBY WILL EXIST. IN WARM AIR ADVECTION PATTERN EXPECT TEMPERATURES TO RUN AROUND 5 DEGREES ABOVE NORMAL...WITH HIGHS RANGING FROM NEAR 80 NE TO THE MID 80S SW. WITH THE PASSAGE OF THE WARM FRONT AND RIDGING IN MID LEVELS THERE WILL BE A LACK OF SIGNIFICANT FORCING THURSDAY NIGHT. HAVE DIMINISHED POPS FROM THE SOUTH WITH A SLIGHT CHANCE EARLY TO DRY OVERNIGHT. SRLY SFC WINDS WILL STAY UP AT 5 TO 10 MPH ALONG WITH CLOUD COVER WILL KEEP TEMPERATURES ON THE WARMER SIDE. EXPECT OVERNIGHT LOWS TO RANGE FROM THE MID 60S SE TO THE UPPER 60S NW. PROGRESSIVE/DIGGING MID LEVEL TROF TO MOVE INTO THE WESTERN GREAT LAKES/UPR MS VLY FRIDAY AND THE GREAT LAKES FRIDAY NIGHT. ASSOCIATED SFC COLD FRONT TO PUSH EAST THRU ILN/S FA FRIDAY NIGHT/EARLY SATURDAY. NAM SOLN IS DEPICTING A PRE-FRONTAL TROF WITH MODERATE INSTBY INTO THE WEST LATE FRIDAY AFTN. GIVEN THE HIGHER RESOLUTION THIS LOOKS REASONABLE. WILL CONTINUE TO RAMP UP POPS TO LKLY LATE IN THE DAY FRIDAY AND THEN CATEGORICAL FRIDAY NIGHT ACRS THE ENTIRE REGION AS THE FRONT PUSHES IN. WILL CONTINUE TO HIGHLIGHT POTENTIAL FOR LOCALLY DAMAGING WINDS AND SOME HAIL WITH SOME OF THE STRONGER STORMS FRIDAY AFTN/EARLY EVENING. THIS WILL BE DEPENDENT ON INSTBY AND WILL LIMIT AREAL EXTENT TO OVER THE WESTERN COUNTIES. GIVEN WAA AHEAD OF THE FRONT...EXPECT TEMPS TO BE CLOSE TO 10 DEGREES ABOVE NORMAL WITH HIGHS ON FRIDAY RANGING FROM THE MID/UPR 80S SE TO THE LOWER 80S FAR NW. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... A COLD FRONT IS EXPECTED TO BE LOCATED THROUGH THE EASTERN PARTS OF THE FA SATURDAY MORNING. SHOWERS AND SOME THUNDERSTORMS WILL LINGER BEHIND THE FRONT ON SATURDAY AS THE UPPER TROUGH SWINGS THROUGH THE OHIO RIVER VALLEY REGION. WIDELY SCATTERED SHOWERS MAY LINGER IN THE SE ON SUNDAY. LATEST ECMWF IS MORE PROGRESSIVE WITH THE FRONT AND FUTURE FORECASTS MAY NEED TO CUT BACK ON PRECIPITATION SATURDAY AFTERNOON AND SUNDAY. ON MONDAY...HIGH PRESSURE WILL BUILD IN FROM THE NORTH. COULD SEE ENOUGH MOISTURE FROM THE LOW MOVING UP THE COAST TO PRODUCE ISOLATED SHOWERS IN THE EXTREME EAST. AFTER MONDAY...SURFACE HIGH PRESSURE EXTENDING INTO THE REGION FROM THE NE WILL BRING DRY WEATHER AND MILD TEMPERATURES. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... SLIGHTLY UNSETTLED WEATHER CONDITIONS WILL CONTINUE THROUGH THE NEXT SEVERAL DAYS. MOISTURE CONTINUES TO INCREASE OVER THE OHIO VALLEY...RESULTING IN INCREASING CLOUDS...AND SHOWERS. THE BIGGEST CONCERN THIS MORNING IS THE POTENTIAL FOR STRATUS DEVELOPMENT. THERE IS HIGH CONFIDENCE IN A THICKENING OF THE LOW- LEVEL MOISTURE OVERNIGHT...WITH UPSTREAM CONDITIONS ALREADY INDICATING MVFR CEILINGS ACROSS MUCH OF KENTUCKY AND IFR CIGS ACROSS MUCH OF THE EASTERN HALF OF OHIO. THESE CLOUDS ARE EXPECTED TO LOWER AS THEY OVERSPREAD THE TAF SITES. THIS WILL MAKE THE FOG FORECAST SOMEWHAT MORE DIFFICULT BECAUSE THE STRATUS SHOULD KEEP THE VSBYS FROM LOWERING TO LIFR MOST AREAS. BOTTOM LINE IS THAT A BLANKET OF IFR CONDITIONS ARE EXPECTED TO DEVELOP ACROSS THE ENTIRE FORECAST AREA OVER THE NEXT FEW HOURS. CEILINGS WILL BE SLOW TO LIFT ON THURSDAY...AS SHOWERS AND LARGE PATCHES OF LATE RAIN OVER SPREAD THE AREA AFTER 09Z ASSOCIATED WITH A SMALL THUNDERSTORM COMPLEX OVER NORTHERN INDIANA MOVING TOWARDS THE SOUTHEAST. WHILE THERE IS A RISK OF THUNDER AS THE PRECIPITATION MOVES IN THIS MORNING...IT IS NOT HIGH ENOUGH TO PUT INTO THE FORECAST AT THIS TIME. SHOWERS AND LOW CLOUDS WITH MVFR CONDITIONS ARE EXPECTED TO LAST INTO THE MID AFTERNOON HOURS. OUTLOOK...THUNDERSTORMS WILL BE POSSIBLE FROM FRIDAY AFTERNOON THROUGH SATURDAY MORNING. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...AR NEAR TERM...HATZOS SHORT TERM...AR LONG TERM...PARKER AVIATION...HAYDU Area Forecast Discussion National Weather Service Lincoln IL 1040 AM CDT Thu Sep 19 2013 .DISCUSSION... ISSUED 1040 AM CDT Thu Sep 19 2013 Warm front has lifted well to the northeast of central Illinois this morning, leaving behind partly to mostly sunny skies and very warm temps in the upper 70s and lower 80s. Convection continues to fire along the edge of the strengthening cap in the warm sector, mainly from southern Lake Michigan S/SE across Indiana into the Ohio River Valley. As warm air aloft spreads further east, this activity will continue to shift further away from Illinois this afternoon. End result will be a hot and mainly dry day, with perhaps a few isolated thunderstorms. Afternoon high temps will reach the upper 80s and lower 90s. Better thunderstorm chances will arrive by late evening across the Illinois River Valley. Latest HRRR shows a line of convection developing along an advancing cold front and pushing toward the Illinois River by around 03z. This activity should continue eastward in a weakening state overnight. Barnes && .AVIATION... ISSUED 655 AM CDT Thu Sep 19 2013 An area of showers and thunderstorms associated with a small MCS will mainly stay east of the central IL terminal airports this morning from Vermilion county ese into Indiana. Carried VCSH over eastern IL airports til 14-15Z with light fog/haze bringing visibilities of 4-6 miles. Isolated convection possible this afternoon and early evening as airmass become more unstable, but coverage too limited to pinpoint down in the TAFs. VFR conditions should generally prevail today and this evening with scattered cumulus clouds and scattered-broken mid level clouds. A cold front extending from 1001 mb low pressure over se part of Lake Winnipeg through western MN thru far nw corner of IA into se Nebraska and nw KS. Cold front slated to push se to near the IL river by PIA around 12Z/7 am Fri. A band of showers and thunderstorms to accompany the cold front and spread se across central IL overnight, reaching PIA after 05Z/midnight and DEC and CMI after 09Z/4 am. MVFR ceilings and visibilities possible with convection overnight. SSW winds around 10 kts early this morning to increase to 10-15 kts with gusts 18-23 kts by 15Z and continue through early evening, then be 10-14 kts tonight and gradually veer sw overnight. 07 && .PREV DISCUSSION... ISSUED 251 AM CDT Thu Sep 19 2013 Developing storm system over the northern Plains to be the main issue for the forecast in the Midwest for this package. High pressure over the Atlantic seaboard slowly sliding eastward with southerly flow ramping up over the region in the middle of the country. Sunshine and WAA will send temperatures well above normal ahead of the storm system. All the warm air in place will provide instability for advancing chances of thunderstorms through tonight and tomorrow. Biggest issues for the forecast revolve around the timing of the front vs. max heating, and speed of the front itself. Ongoing convection already starting to hint that the mesoscale influences with prefrontal trofs and outflow boundaries will more than likely complicate the forecast of the details. Best chances for precip tonight and through tomorrow. SHORT TERM...Today and tomorrow... Hot today with the ridge expanding into the Midwest. Warmest midlevels in western CWA but will likely be countered somewhat by advancing clouds. However, front will hold off enough to see upper 80s over majority of the area. Cold front has slowed progression to tomorrow but convection ahead of the front and associated cold pools will mask some of the distinction of the leading edge. Plenty of instability in the region...but the cold front being delayed a bit results in the FA barely clipped by the slight risk outlook to the northwest for tonight. Frontal progression tomorrow to be slower, and already in rain and cloud cover from the overnight will likely inhibit intense storm development. So far tomorrow remains in a general thunder. Overnight Friday will see a clearing from west to east. Will need to keep an eye on guidance NW of Interstate 55 corridor for rapid clearing may result in a need for an adjustment of the lows down a couple degrees. LONG TERM...Saturday through Wednesday... Milder weather and dry through the extended. High pressure dominates the eastern half of the country and temperatures remain milder and closer to normal...with heat building again under a thermal ridge in the southwestern US. With southwesterly flow kicking in next week Tues, the extended could see some warmer temps as time draws nearer should the pattern persist. Guidance is still being pulled to 70s by climatology at this point. HJS && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1045 AM EDT THU SEP 19 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 355 AM EDT THU SEP 19 2013 AN UPPER RIDGE WILL BE ACROSS CENTRAL INDIANA THROUGH THIS EVENING AS WARM MOIST AND UNSTABLE AIR MOVES IN FROM THE SOUTH ON THE BACK SIDE OF SURFACE HIGH PRESSURE ACROSS THE EASTERN STATES. THERE IS A CHANCE OF THUNDERSTORMS MAINLY THIS AFTERNOON AND EVENING AS WEAK WAVES MOVE OVERTOP THE RIDGE AND THE ATMOSPHERE BECOMES VERY UNSTABLE. THUNDERSTORMS WILL BECOME WIDESPREAD FRIDAY AND FRIDAY NIGHT AS A COLD FRONT DROPS SOUTHEAST ACROSS CENTRAL INDIANA FRIDAY NIGHT. THERE COULD BE A FEW LINGERING MORNING THUNDERSTORMS SATURDAY MORNING ACROSS SOUTHEASTERN PARTS OF CENTRAL INDIANA. OTHERWISE...HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT ALLOW FOR COOLER TEMPERATURES AND DRY WEATHER THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /REST OF TODAY AND TONIGHT/... ISSUED AT 1008 AM EDT THU SEP 19 2013 .UPDATE... NUMEROUS SHOWERS AND THUNDERSTORMS WILL LAST THROUGH MIDDAY AND... AND INTO EARLY AFTERNOON OVER EASTERN SECTIONS OF THE REGION. RAPID REFRESH THIS CONVECTION UNTIL MID AFTERNOON OVER THE EAST. AFTER THAT WILL CONTINUE WITH THE SCENARIO THAT THUNDERSTORMS WILL DIMINISH BY LATE AFTERNOON PER NAM AND RAPID REFRESH MODELS. IN REGARDS TO TEMPERATURES LATEST RAP INDICATES HIGH TEMPERATURES APPROACHING 90 FAR WEST WHERE THERE WILL BE MORE SUNSHINE THIS AFTERNOON TO RAISE TEMPERATURES. OVER THE EAST CLOUDS AND LINGERING PRECIPITATION MAY KEEP HIGH TEMPERATURES CLOSER TO 80. NO CHANGES WILL BE MADE AT THIS TIME TONIGHT. NAM SUGGESTS INDICATES THERE SHOULD BE A LULL IN ANY THUNDERSTORM ACTIVITY MOST OF TONIGHT AND THEN CHANCES INCREASING TOWARDS DAYBREAK WEST AS COLD FRONT APPROACHES. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... ISSUED AT 355 AM EDT THU SEP 19 2013 MAIN CHALLENGE TO THE SHORT TERM WILL CONTINUE TO BE POPS ALONG WITH TIMING OF SHOWER ACTIVITY OUT OF THE FORECAST AREA. MODELS ARE NOW IN GOOD AGREEMENT ON FRONTAL TIMING AND WILL GO WITH A BLEND THAT SUGGESTS THE APPROACHING STRONG NORTHERN UPPER TROUGH WILL FORCE THE FRONT TO NEAR LAFAYETTE BY 00Z SATURDAY AND THEN SOUTHEAST OF CENTRAL INDIANA AFTER 09Z SATURDAY. THE SPC DAY2 OUTLOOK AS THROWN ROUGHLY OUR SOUTHEASTERN HALF OF THE FORECAST IN A SLIGHT RISK OF SEVERE WEATHER FOR FRIDAY AFTERNOON AND EVENING. THIS SEEMS REASONABLE AS THE LOW LEVEL JET WILL BE OVER THIS AREA AFTER 18Z FRIDAY...AND WITH PLENTY OF WIDESPREAD ACTIVITY EXPECTED ACROSS THE NORTHWEST HALF OF THE FORECAST AREA DURING THE MORNING AND AFTERNOON...THAT PART OF THE FORECAST AREA WILL HAVE A HARD TIME DESTABILIZING AS MUCH AS THE SOUTHEAST. EVEN SOUTHEAST...ONLY EXPECT AN ISOLATED SEVERE STORM OR TWO WITH MARGINAL SHEAR AND INSTABILITY. WILL GO WITH OCCASIONAL POPS FRIDAY SPREADING SOUTHEAST DURING THE AFTERNOON AND NIGHT. WILL LEAVE SMALL CHANCE LINGER SHOWERS SATURDAY MORNING...OTHERWISE...HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT WHICH WILL BRING DRY WEATHER IN FOR THE REST OF THE WEEKEND ALONG WITH COOLER TEMPERATURES PER MOS AND MODEL BLEND. HEAVY RAIN WILL CONTINUE TO BE A THREAT THROUGH FRIDAY NIGHT WITH PRECIPITABLE WATER VALUES NOT DROPPING MUCH UNTIL OVERNIGHT FRIDAY NIGHT. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... ISSUED AT 355 AM EDT THU SEP 19 2013 DRY FORECAST THIS PERIOD WITH SEASONABLE TEMPERATURES. GFS AND ECMWF DEPICT A CUT OFF UPPER LOW MOVING THROUGH THE APPALACHIANS EARLY IN THE PERIOD WHILE RIDGING ALOFT AND STRONG SUBSIDENCE OVER THE MISSISSIPPI RIVER VALLEY PROVIDES A NORTHERLY FLOW OF AIR AS IT SLOWLY BUILDS EAST DURING THE PERIOD. AS THE RIDGE MOVES EAST OVER INDIANA BY THE MIDDLE OF NEXT WEEK...TEMPS WILL SLOWLY MODERATE TO SLIGHTLY ABOVE NORMAL AS RETURN FLOW BEGINS. && .AVIATION /DISCUSSION FOR THE 191500Z TAF UPDATE/... ISSUED AT 1045 AM EDT THU SEP 19 2013 RADAR LOOP SHOWS AREAS OF THUNDERSTORMS WEST OF KIND AND AROUND AND SOUTH AND SOUTHEAST OF KBMG. THINK CONVECTIVE THREAT WILL REMAIN RATHER HIGH ACROSS THESE TAF SITES UNTIL THIS WAVE PASSES BY AROUND 191700Z OR SO WITH CONVECTIVE THREAT EAST OF KHUF AND KLAF. BRIEF IFR VISIBILITY/CEILING RESTRICTIONS IN THE HEAVIER SHOWERS. OTHERWISE...AREAS OF CEILINGS AROUND 020-025 EXPECTED THIS MORNING AS WELL...ESPECIALLY AT KLAF/KIND...WITH CEILINGS GRADUALLY LIFTING INTO A HIGHER DECK BY THIS AFTERNOON AS WAVE PULLS OFF TO THE EAST. OUTSIDE OF ANY CONVECTION...SURFACE WINDS GENERALLY AROUND 10 KTS OR LESS TODAY. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MK NEAR TERM...JH SHORT TERM...MK LONG TERM....JAS AVIATION...JAS/CP VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1008 AM EDT THU SEP 19 2013 .UPDATE... NEAR TERM FOR THE REST OF TODAY HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 355 AM EDT THU SEP 19 2013 AN UPPER RIDGE WILL BE ACROSS CENTRAL INDIANA THROUGH THIS EVENING AS WARM MOIST AND UNSTABLE AIR MOVES IN FROM THE SOUTH ON THE BACK SIDE OF SURFACE HIGH PRESSURE ACROSS THE EASTERN STATES. THERE IS A CHANCE OF THUNDERSTORMS MAINLY THIS AFTERNOON AND EVENING AS WEAK WAVES MOVE OVERTOP THE RIDGE AND THE ATMOSPHERE BECOMES VERY UNSTABLE. THUNDERSTORMS WILL BECOME WIDESPREAD FRIDAY AND FRIDAY NIGHT AS A COLD FRONT DROPS SOUTHEAST ACROSS CENTRAL INDIANA FRIDAY NIGHT. THERE COULD BE A FEW LINGERING MORNING THUNDERSTORMS SATURDAY MORNING ACROSS SOUTHEASTERN PARTS OF CENTRAL INDIANA. OTHERWISE...HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT ALLOW FOR COOLER TEMPERATURES AND DRY WEATHER THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /REST OF TODAY AND TONIGHT/... ISSUED AT 1008 AM EDT THU SEP 19 2013 .UPDATE... NUMEROUS SHOWERS AND THUNDERSTORMS WILL LAST THROUGH MIDDAY AND... AND INTO EARLY AFTERNOON OVER EASTERN SECTIONS OF THE REGION. RAPID REFRESH THIS CONVECTION UNTIL MID AFTERNOON OVER THE EAST. AFTER THAT WILL CONTINUE WITH THE SCENARIO THAT THUNDERSTORMS WILL DIMINISH BY LATE AFTERNOON PER NAM AND RAPID REFRESH MODELS. IN REGARDS TO TEMPERATURES LATEST RAP INDICATES HIGH TEMPERATURES APPROACHING 90 FAR WEST WHERE THERE WILL BE MORE SUNSHINE THIS AFTERNOON TO RAISE TEMPERATURES. OVER THE EAST CLOUDS AND LINGERING PRECIPITATION MAY KEEP HIGH TEMPERATURES CLOSER TO 80. NO CHANGES WILL BE MADE AT THIS TIME TONIGHT. NAM SUGGESTS INDICATES THERE SHOULD BE A LULL IN ANY THUNDERSTORM ACTIVITY MOST OF TONIGHT AND THEN CHANCES INCREASING TOWARDS DAYBREAK WEST AS COLD FRONT APPROACHES. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... ISSUED AT 355 AM EDT THU SEP 19 2013 MAIN CHALLENGE TO THE SHORT TERM WILL CONTINUE TO BE POPS ALONG WITH TIMING OF SHOWER ACTIVITY OUT OF THE FORECAST AREA. MODELS ARE NOW IN GOOD AGREEMENT ON FRONTAL TIMING AND WILL GO WITH A BLEND THAT SUGGESTS THE APPROACHING STRONG NORTHERN UPPER TROUGH WILL FORCE THE FRONT TO NEAR LAFAYETTE BY 00Z SATURDAY AND THEN SOUTHEAST OF CENTRAL INDIANA AFTER 09Z SATURDAY. THE SPC DAY2 OUTLOOK AS THROWN ROUGHLY OUR SOUTHEASTERN HALF OF THE FORECAST IN A SLIGHT RISK OF SEVERE WEATHER FOR FRIDAY AFTERNOON AND EVENING. THIS SEEMS REASONABLE AS THE LOW LEVEL JET WILL BE OVER THIS AREA AFTER 18Z FRIDAY...AND WITH PLENTY OF WIDESPREAD ACTIVITY EXPECTED ACROSS THE NORTHWEST HALF OF THE FORECAST AREA DURING THE MORNING AND AFTERNOON...THAT PART OF THE FORECAST AREA WILL HAVE A HARD TIME DESTABILIZING AS MUCH AS THE SOUTHEAST. EVEN SOUTHEAST...ONLY EXPECT AN ISOLATED SEVERE STORM OR TWO WITH MARGINAL SHEAR AND INSTABILITY. WILL GO WITH OCCASIONAL POPS FRIDAY SPREADING SOUTHEAST DURING THE AFTERNOON AND NIGHT. WILL LEAVE SMALL CHANCE LINGER SHOWERS SATURDAY MORNING...OTHERWISE...HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT WHICH WILL BRING DRY WEATHER IN FOR THE REST OF THE WEEKEND ALONG WITH COOLER TEMPERATURES PER MOS AND MODEL BLEND. HEAVY RAIN WILL CONTINUE TO BE A THREAT THROUGH FRIDAY NIGHT WITH PRECIPITABLE WATER VALUES NOT DROPPING MUCH UNTIL OVERNIGHT FRIDAY NIGHT. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... ISSUED AT 355 AM EDT THU SEP 19 2013 DRY FORECAST THIS PERIOD WITH SEASONABLE TEMPERATURES. GFS AND ECMWF DEPICT A CUT OFF UPPER LOW MOVING THROUGH THE APPALACHIANS EARLY IN THE PERIOD WHILE RIDGING ALOFT AND STRONG SUBSIDENCE OVER THE MISSISSIPPI RIVER VALLEY PROVIDES A NORTHERLY FLOW OF AIR AS IT SLOWLY BUILDS EAST DURING THE PERIOD. AS THE RIDGE MOVES EAST OVER INDIANA BY THE MIDDLE OF NEXT WEEK...TEMPS WILL SLOWLY MODERATE TO SLIGHTLY ABOVE NORMAL AS RETURN FLOW BEGINS. && .AVIATION /DISCUSSION FOR THE 191200Z TAFS/... ISSUED AT 725 AM EDT THU SEP 19 2013 ORGANIZED AREA OF CONVECTION CONTINUES TO DROP SOUTHEAST ACROSS THE CENTRAL SECTIONS OF THE FORECAST AREA...AIDED BY A 25-30KT LOW LEVEL JET. BASED ON ITS MOVEMENT...APPEARS IT SHOULD BE OUT OF THE KIND VICINITY BY OR SHORTLY AFTER ISSUANCE TIME. ADDITIONAL CONVECTION DEVELOPING BEHIND THIS AREA AHEAD OF AN UPPER WAVE CURRENTLY MOVING THROUGH EASTERN ILLINOIS. THINK CONVECTIVE THREAT WILL REMAIN RATHER HIGH ACROSS THE TAF SITES UNTIL THIS WAVE PASSES BY AROUND 191700Z OR SO. BRIEF IFR VISIBILITY RESTRICTIONS IN THE HEAVIER SHOWERS. OTHERWISE...SOME MVFR VISIBILITY RESTRICTIONS IN LIGHT FOG EXPECTED TO LIFT BY THE MID MORNING HOURS. AREAS OF CEILINGS AROUND 020-025 EXPECTED THIS MORNING AS WELL...ESPECIALLY AT KLAF/KIND...WITH CEILINGS GRADUALLY LIFTING INTO A HIGHER DECK BY THIS AFTERNOON AS WAVE PULLS OFF TO THE EAST. OUTSIDE OF ANY CONVECTION...SURFACE WINDS GENERALLY AROUND 10 KTS OR LESS TODAY. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MK NEAR TERM...JH SHORT TERM...MK LONG TERM....JAS AVIATION...JAS VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
921 AM MDT THU SEP 19 2013 .UPDATE... ISSUED AT 909 AM MDT THU SEP 19 2013 AREA OF PRECIPITATION CONTINUES TO MARCH EAST AHEAD OF A COLD FRONT THAT HAS MOVED THROUGH THE WEST HALF OF THE AREA SO FAR. BEST CHANCES FOR RAINFALL CONTINUE TO LOOK TO BE OVER THE FAR EAST AS LIFT FROM THE COLD FRONT COMBINED WITH AN UPPER LEVEL TROUGH WILL MOVE THROUGH AROUND NOON. BEHIND THE FRONT NORTHERLY WINDS HAVE BECOME GUSTY...RANGING FROM 20-30 MPH WITH SOME GUSTS NEARING 40 MPH IN FAR NORTHEAST COLORADO. THE GUSTS SHOULD START TO DECLINE BY THE EARLY AFTERNOON AS THE SURFACE PRESSURE GRADIENT BEHIND THE FRONT SLACKENS. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 358 AM MDT THU SEP 19 2013 FORECAST PROBLEMS WILL BE PRECIPITATION CHANCES TODAY...HOW COOL TO MAKE HIGHS AND LOWS THROUGH FRIDAY NIGHT AND HOW MUCH TO WARM THINGS UP ON SATURDAY. SATELLITE SHOWING AN ACTIVE FLOW FROM THE PACIFIC INTO NORTH AMERICA. THE FLOW WAS AMPLIFYING SOME OVER THE PACIFIC... ESPECIALLY ALONG THE WEST COAST. ONE SYSTEM IS PUSHING EAST ALONG THE U.S AND CANADIAN BORDER. OUTFLOW FROM THUNDERSTORM CLUSTER TO OUR NORTH HAS PUSHED THROUGH THE AREA WITH A COLD FRONT APPROACHING FROM THE NORTHWEST. AT JET LEVEL...THE SREF WAS DOING A LITTLE BETTER WITH THE JET DEPICTION OVER OUR AREA. AT MID LEVELS...MODELS WERE HAVING A LITTLE TROUBLE THE SPEED AND AMPLITUDE OF THE NORTHERN LOW. AT THIS TIME IT APPEARS THE GFS AND UKMET WERE DOING A LITTLE BETTER THAN THE ECMWF AND CANADIAN. THE RUC WAS CATCHING THE INITIAL WIND FIELD THE BEST WITH THE ECMWF NOT TOO FAR BEHIND. THE UKMET AND GFS WERE DOING A LITTLE BETTER THAN THE OTHER OUTPUT ON THE LOW LEVEL THERMAL FIELD. TODAY/TONIGHT...INTERESTING PRECIPITATION FORECAST. INITIAL ROUND OF THUNDERSTORMS WERE CAUSED BY INITIAL SURFACE TROUGH AND OUTFLOW BOUNDARY FROM CLUSTER OF THUNDERSTORMS THAT MOVED TO THE NORTH OF OUR FORECAST AREA. HOWEVER ADDITIONAL DEVELOPMENT IS NOW OCCURRING IN ADVANCE OF COLD FRONT WHICH IS VERY NEAR THE NORTHWEST CORNER OF THE FORECAST AREA. ALSO AT THIS TIME...MAIN SHORTWAVE TROUGH ROTATING AROUND NORTHERN UPPER LOW IS BEGINNING TO MOVE IN FROM THE WEST. ALSO THE RIGHT REAR QUADRANT OF THE JET IS NEAR/OVER THE WESTERN END OF THE FORECAST. DURING THE DAY THEY ALL HANDLE IT DIFFERENTLY. HOWEVER...BY THE END OF THE AFTERNOON INTO THE EARLY AFTERNOON...THE RIGHT REAR QUADRANT IS OVER OR NEAR THE EASTERN END OF THE AREA. IN ADVANCE OF ALL THESE FEATURES THERE APPEARS ENOUGH ELEVATED CAPE WITH FAVORABLE THETA-E LAPSE RATES TO ALLOW FOR A GOOD RESPONSE TO THE LIFT. AT THIS TIME IT LOOKS LIKE THE FAVORED AREA FOR THUNDERSTORMS IS ALONG AND EAST OF THE COLORADO BORDER...GETTING HIGHER AS YOU GO EAST. KEPT THIS GENERAL IDEA FROM THE DAY SHIFT BUT RAISED POPS SLIGHTLY FURTHER EAST. THUNDERSTORMS LOOK TO BE DONE BY LATE IN THE DAY. DEFINITELY LOOKS COOLER. THE QUESTION IS HOW MUCH. THE AMOUNT OF TEMPERATURE CHANGE OVER YESTERDAY WOULD YIELD SLIGHTLY COOLER TEMPERATURES THAN WHAT I HAVE IN THERE NOW. DID MAKE SLIGHT ADJUSTMENTS COOLER IN LINE WITH THE BIAS ADJUSTMENT TO THE 850 MB TEMPERATURES. THIS TENDED TO BE IN THE MIDDLE OF THE GUIDANCE. WILL BE A RATHER COOL NIGHT TONIGHT WITH LITTLE CLOUD COVER AND LIGHT WINDS. MODELS DIFFER ON WHERE THE LIGHTEST WINDS WILL BE. AT THIS TIME IT LOOKS THEY WILL BE IN THE WESTERN AND NORTHERN SECTIONS AND ADJUSTED ACCORDINGLY. FRIDAY/FRIDAY NIGHT...MID/UPPER RIDGE BUILDING INTO THE AREA WILL MAKE FOR DRY CONDITIONS AND LITTLE TO NO CLOUD COVER. SURFACE RIDGE JUST PULLING OFF TO THE EAST DURING THE DAY WITH LIGHT AND VARIABLE WINDS...ESPECIALLY IN THE EAST. MODELS ARE INDICATING TEMPERATURES NEAR WHAT THEY ARE TO BE TODAY. ONLY MADE SLIGHT ADJUSTMENTS BASED ON THAT. SOME DIFFERENCES IN HOW COOL TO MAKE THE MINS. THE NAM STARTS WARM ADVECTION MUCH FASTER WITH THE OTHER MODELS SLOWER. IT SHOULD BE WARMER BUT AM NOT GOING AS WARM AS THE NAM. SATURDAY/SATURDAY NIGHT...MID/UPPER LEVEL RIDGE STARTS PUSHING EAST LATE IN THE DAY AND ESPECIALLY IN THE NIGHT WITH SOUTHWEST FLOW ALOFT DEVELOPING OVER THE AREA. THIS RIDGE PLUS VERY DRY/WELL MIXED AIR MASS ALOFT WILL KEEP CONDITIONS DRY...DESPITE THE FACT AN UPPER JET APPROACHES THE WESTERN PORTIONS OF THE AREA LATE IN THE NIGHT. SHOULD BE WARMER...QUESTION IS HOW MUCH WARMER. NAM CONTINUES TO BE THE MOST AGGRESSIVE WITH THIS. WIND FIELD AND CONSENSUS OF 850 MB TEMPERATURES SUPPORT GOING COOLER. THIS IS CLOSE TO WHAT CURRENT FORECAST HAS IN THERE AND ONLY MADE SLIGHT ADJUSTMENTS. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 300 AM MDT THU SEP 19 2013 A SHORTWAVE TROUGH WILL QUICKLY MOVE THROUGH SUNDAY NIGHT. THE STRONGEST FORCING WILL BE NORTH OF THE FORECAST AREA ACROSS NEBRASKA WHERE GFS ENSEMBLE MEAN QPF VALUES ARE HIGHEST. ISOLATED TO SCATTERED CONVECTION SHOULD IMPACT THE WESTERN PORTION OF THE FORECAST AREA BY SUNDAY EVENING AND THEN OVERSPREAD THE REST OF THE AREA OVERNIGHT. THE GREATEST RAIN CHANCES AND POTENTIAL FOR THE HIGHEST RAINFALL AMOUNTS WILL BE OVER ROUGHLY THE NORTHEASTERN HALF OF THE FORECAST AREA. SLIGHTLY COOLER TEMPERATURES WILL ARRIVE BEHIND THIS SHORTWAVE AND ASSOCIATED COLD FRONT ON MONDAY BUT COLD AIR ADVECTION IN THE WAKE OF THIS SYSTEM IS BRIEF AND INSIGNIFICANT. STRONG EAST TO WEST ORIENTED MID/UPPER FLOW WILL BE SITUATED OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS ON TUESDAY. BY MID WEEK A LARGE TROUGH EVOLVES OVER THE WESTERN CONUS. MODELS DIFFER ON HOW THIS TROUGH WILL EVOLVE BY MID WEEK WITH GFS AND ECMWF DIFFERING ON THE POSITION OF CLOSED UPPER LOW...MEANWHILE GFS ENSEMBLE MEAN DEPICTS A MORE OPEN/PROGRESSIVE TROUGH. IN EITHER SCENARIO...SIGNIFICANT IMPACTS TO OUR AREA ARE NOT EXPECTED THROUGH THE END OF THE EXTENDED PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 545 AM MDT THU SEP 19 2013 VFR CONDITIONS ARE EXPECTED TO CONTINUE FOR THE TAF PERIOD AT BOTH TAF SITES. A SMALL SPREAD IN TEMPERATURE AND DEW POINT AT MCK COULD LEAD TO MINOR REDUCTION OF VISIBILITY BRIEFLY THIS MORNING...BUT NO VISIBILITY OR CEILING RESTRICTIONS ARE EXPECTED. THERE IS SOME DISAGREEMENT IN MODEL GUIDANCE ON HOW EXTENSIVE CLOUDS WILL BE THROUGH AFTERNOON. A BROKEN DECK IS A POSSIBILITY BUT SHOULD REMAIN JUST ABOVE MVFR CRITERIA. WINDS WILL INCREASE THIS AFTERNOON FROM THE NORTH AND VEER TO A NORTHEASTERLY DIRECTION BY EVENING. GUSTS OVER 20 KNOTS ARE EXPECTED FROM LATE MORNING THROUGH MID AFTERNOON. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JTL SHORT TERM...BULLER LONG TERM...BRB AVIATION...BRB
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
857 AM CDT Thu Sep 19 2013 ...Updated to precipitation chances today... .SYNOPSIS... ISSUED AT 1020 PM CDT WED SEP 18 2013 Water vapor imagery and upper air analysis indicate an upper level trough of low pressure pushing eastward across the northern Rockies of Montana and Wyoming. Near the surface, a lee side trough of low pressure remains anchored across extreme eastern Colorado. Surface dewpoints are in the upper 50s(F) to the lower and mid 60s(F) across central and southwest Kansas. && .UPDATE... ISSUED AT 844 AM CDT THU SEP 19 2013 Scatted showers and even a few isolated thunderstorms will continue across western and north central Kansas as an upper level disturbance based the nam 450mb- 400mb pv lifts northeast across western Kansas. HRRR appears to have a decent handle on this so will lean in that direction for precipitation chances through the early afternoon. Thunderstorms still appear become more widespread across south central Kansas during the mid to late afternoon as a cold front moves into south central Kansas, late day instability, and the location of the left exit region of an upper level jet at 00z Friday. Also trended towards a non diurnal trend in temperatures this afternoon behind the cold front as it crosses western Kansas. && .SHORT TERM...(Today and tonight) ISSUED AT 212 AM CDT THU SEP 19 2013 Short range models indicate the upper level trough kicking out of the Rockies into the Northern Plains today setting up shower and thunderstorm chances across the Upper Midwest southwestward into the Central Plains, including portions of central and western Kansas. As the upper level trough moves into the Dakotas and Nebraska, an attendant cold front will push southeastward into western Kansas late this morning into the afternoon. Meanwhile, a +85kt upper level jet is projected to climb northeast out of the desert southwest into western and central Kansas from this afternoon into this evening. Along with more favorable dynamic support aloft, steepening mid level lapse rates and increased instability will be enough to support thunderstorm development along and ahead of the cold front as it begins to push further southeast into more favorable moisture across central Kansas and eastern portions of southwest Kansas. Although vertical shear profiles are not exactly ideal, CAPE values in excess of 2000 J/KG ahead of the front will be enough to support strong to marginally severe thunderstorms...mainly southeast of a Hays to Liberal line. The potential for heavy rainfall exists as well with NAM/GFS model soundings showing PW values up around 1.5 inches. Temperatures are expected to climb back up into the lower 90s(F) across south central Kansas where the frontal passage isn`t likely to occur until late this afternoon. Otherwise, look for highs up into the upper 70s(F) and 80s(F) behind the front with the cooler temperatures across west central Kansas. Lows generally down into the 50s(F) are likely tonight as much cooler air filters south into western Kansas overnight. .LONG TERM...(Friday through Wednesday) ISSUED AT 311 AM CDT THU SEP 19 2013 A deep upper level shortwave trough will be moving out of the northern and central plains by Friday morning. The associated surface cold front will be well to the southeast of western Kansas with clear skies and cooler temperatures in its wake. The medium range models show a fairly progressive upper level pattern across North America through the remainder of the extended period. An upper level ridge will move east over the central High Plains Saturday and Sunday before another strong shortwave trough moves out of the Rockies into the central High Plains Sunday night and Monday. The atmosphere is not progged to be overly unstable but the GFS and ECMWF both show a 70 knot upper level jet propagating across the Oklahoma/Texas panhandles Sunday night. With western Kansas under the left exit region of this jet, think that the going 30-40 percent pops for thunderstorms looks reasonable. Upper level ridging builds back over the central part of the country through midweek ahead of another strong wave that digs into the western states. We should see dry weather through midweek before precipitation chances increase by next weekend. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) ISSUED AT 649 AM CDT THU SEP 19 2013 Widely scattered thunderstorms will be possible across western and central Kansas today as a cold front pushes south across the western part of the state. Will carry VCTS at the taf sites through much of the day. Depending on thunderstorm trends, thunderstorms may need to be added to tempo or prevailing groups this afternoon. Southwesterly winds will become westerly ahead of the front this morning before switching to the north to northeast behind the front this afternoon. Showers and thunderstorms will be moving out of the region by this evening. && .PRELIMINARY POINT TEMPS/POPS... DDC 85 55 78 50 / 30 30 0 0 GCK 80 53 76 50 / 30 10 0 0 EHA 82 52 76 52 / 40 10 0 0 LBL 85 55 79 51 / 30 20 0 0 HYS 80 52 75 50 / 40 10 0 0 P28 92 60 80 52 / 80 80 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Burgert SYNOPSIS...JJohnson SHORT TERM...JJohnson LONG TERM...Gerard AVIATION...Gerard
AREA FORECAST DISCUSSION
NWS GOODLAND KS
545 AM MDT THU SEP 19 2013 .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 358 AM MDT THU SEP 19 2013 FORECAST PROBLEMS WILL BE PRECIPITATION CHANCES TODAY...HOW COOL TO MAKE HIGHS AND LOWS THROUGH FRIDAY NIGHT AND HOW MUCH TO WARM THINGS UP ON SATURDAY. SATELLITE SHOWING AN ACTIVE FLOW FROM THE PACIFIC INTO NORTH AMERICA. THE FLOW WAS AMPLIFYING SOME OVER THE PACIFIC... ESPECIALLY ALONG THE WEST COAST. ONE SYSTEM IS PUSHING EAST ALONG THE U.S AND CANADIAN BORDER. OUTFLOW FROM THUNDERSTORM CLUSTER TO OUR NORTH HAS PUSHED THROUGH THE AREA WITH A COLD FRONT APPROACHING FROM THE NORTHWEST. AT JET LEVEL...THE SREF WAS DOING A LITTLE BETTER WITH THE JET DEPICTION OVER OUR AREA. AT MID LEVELS...MODELS WERE HAVING A LITTLE TROUBLE THE SPEED AND AMPLITUDE OF THE NORTHERN LOW. AT THIS TIME IT APPEARS THE GFS AND UKMET WERE DOING A LITTLE BETTER THAN THE ECMWF AND CANADIAN. THE RUC WAS CATCHING THE INITIAL WIND FIELD THE BEST WITH THE ECMWF NOT TOO FAR BEHIND. THE UKMET AND GFS WERE DOING A LITTLE BETTER THAN THE OTHER OUTPUT ON THE LOW LEVEL THERMAL FIELD. TODAY/TONIGHT...INTERESTING PRECIPITATION FORECAST. INITIAL ROUND OF THUNDERSTORMS WERE CAUSED BY INITIAL SURFACE TROUGH AND OUTFLOW BOUNDARY FROM CLUSTER OF THUNDERSTORMS THAT MOVED TO THE NORTH OF OUR FORECAST AREA. HOWEVER ADDITIONAL DEVELOPMENT IS NOW OCCURRING IN ADVANCE OF COLD FRONT WHICH IS VERY NEAR THE NORTHWEST CORNER OF THE FORECAST AREA. ALSO AT THIS TIME...MAIN SHORTWAVE TROUGH ROTATING AROUND NORTHERN UPPER LOW IS BEGINNING TO MOVE IN FROM THE WEST. ALSO THE RIGHT REAR QUADRANT OF THE JET IS NEAR/OVER THE WESTERN END OF THE FORECAST. DURING THE DAY THEY ALL HANDLE IT DIFFERENTLY. HOWEVER...BY THE END OF THE AFTERNOON INTO THE EARLY AFTERNOON...THE RIGHT REAR QUADRANT IS OVER OR NEAR THE EASTERN END OF THE AREA. IN ADVANCE OF ALL THESE FEATURES THERE APPEARS ENOUGH ELEVATED CAPE WITH FAVORABLE THETA-E LAPSE RATES TO ALLOW FOR A GOOD RESPONSE TO THE LIFT. AT THIS TIME IT LOOKS LIKE THE FAVORED AREA FOR THUNDERSTORMS IS ALONG AND EAST OF THE COLORADO BORDER...GETTING HIGHER AS YOU GO EAST. KEPT THIS GENERAL IDEA FROM THE DAY SHIFT BUT RAISED POPS SLIGHTLY FURTHER EAST. THUNDERSTORMS LOOK TO BE DONE BY LATE IN THE DAY. DEFINITELY LOOKS COOLER. THE QUESTION IS HOW MUCH. THE AMOUNT OF TEMPERATURE CHANGE OVER YESTERDAY WOULD YIELD SLIGHTLY COOLER TEMPERATURES THAN WHAT I HAVE IN THERE NOW. DID MAKE SLIGHT ADJUSTMENTS COOLER IN LINE WITH THE BIAS ADJUSTMENT TO THE 850 MB TEMPERATURES. THIS TENDED TO BE IN THE MIDDLE OF THE GUIDANCE. WILL BE A RATHER COOL NIGHT TONIGHT WITH LITTLE CLOUD COVER AND LIGHT WINDS. MODELS DIFFER ON WHERE THE LIGHTEST WINDS WILL BE. AT THIS TIME IT LOOKS THEY WILL BE IN THE WESTERN AND NORTHERN SECTIONS AND ADJUSTED ACCORDINGLY. FRIDAY/FRIDAY NIGHT...MID/UPPER RIDGE BUILDING INTO THE AREA WILL MAKE FOR DRY CONDITIONS AND LITTLE TO NO CLOUD COVER. SURFACE RIDGE JUST PULLING OFF TO THE EAST DURING THE DAY WITH LIGHT AND VARIABLE WINDS...ESPECIALLY IN THE EAST. MODELS ARE INDICATING TEMPERATURES NEAR WHAT THEY ARE TO BE TODAY. ONLY MADE SLIGHT ADJUSTMENTS BASED ON THAT. SOME DIFFERENCES IN HOW COOL TO MAKE THE MINS. THE NAM STARTS WARM ADVECTION MUCH FASTER WITH THE OTHER MODELS SLOWER. IT SHOULD BE WARMER BUT AM NOT GOING AS WARM AS THE NAM. SATURDAY/SATURDAY NIGHT...MID/UPPER LEVEL RIDGE STARTS PUSHING EAST LATE IN THE DAY AND ESPECIALLY IN THE NIGHT WITH SOUTHWEST FLOW ALOFT DEVELOPING OVER THE AREA. THIS RIDGE PLUS VERY DRY/WELL MIXED AIR MASS ALOFT WILL KEEP CONDITIONS DRY...DESPITE THE FACT AN UPPER JET APPROACHES THE WESTERN PORTIONS OF THE AREA LATE IN THE NIGHT. SHOULD BE WARMER...QUESTION IS HOW MUCH WARMER. NAM CONTINUES TO BE THE MOST AGGRESSIVE WITH THIS. WIND FIELD AND CONSENSUS OF 850 MB TEMPERATURES SUPPORT GOING COOLER. THIS IS CLOSE TO WHAT CURRENT FORECAST HAS IN THERE AND ONLY MADE SLIGHT ADJUSTMENTS. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 300 AM MDT THU SEP 19 2013 A SHORTWAVE TROUGH WILL QUICKLY MOVE THROUGH SUNDAY NIGHT. THE STRONGEST FORCING WILL BE NORTH OF THE FORECAST AREA ACROSS NEBRASKA WHERE GFS ENSEMBLE MEAN QPF VALUES ARE HIGHEST. ISOLATED TO SCATTERED CONVECTION SHOULD IMPACT THE WESTERN PORTION OF THE FORECAST AREA BY SUNDAY EVENING AND THEN OVERSPREAD THE REST OF THE AREA OVERNIGHT. THE GREATEST RAIN CHANCES AND POTENTIAL FOR THE HIGHEST RAINFALL AMOUNTS WILL BE OVER ROUGHLY THE NORTHEASTERN HALF OF THE FORECAST AREA. SLIGHTLY COOLER TEMPERATURES WILL ARRIVE BEHIND THIS SHORTWAVE AND ASSOCIATED COLD FRONT ON MONDAY BUT COLD AIR ADVECTION IN THE WAKE OF THIS SYSTEM IS BRIEF AND INSIGNIFICANT. STRONG EAST TO WEST ORIENTED MID/UPPER FLOW WILL BE SITUATED OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS ON TUESDAY. BY MID WEEK A LARGE TROUGH EVOLVES OVER THE WESTERN CONUS. MODELS DIFFER ON HOW THIS TROUGH WILL EVOLVE BY MID WEEK WITH GFS AND ECMWF DIFFERING ON THE POSITION OF CLOSED UPPER LOW...MEANWHILE GFS ENSEMBLE MEAN DEPICTS A MORE OPEN/PROGRESSIVE TROUGH. IN EITHER SCENARIO...SIGNIFICANT IMPACTS TO OUR AREA ARE NOT EXPECTED THROUGH THE END OF THE EXTENDED PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 545 AM MDT THU SEP 19 2013 VFR CONDITIONS ARE EXPECTED TO CONTINUE FOR THE TAF PERIOD AT BOTH TAF SITES. A SMALL SPREAD IN TEMPERATURE AND DEW POINT AT MCK COULD LEAD TO MINOR REDUCTION OF VISIBILITY BRIEFLY THIS MORNING...BUT NO VISIBILITY OR CEILING RESTRICTIONS ARE EXPECTED. THERE IS SOME DISAGREEMENT IN MODEL GUIDANCE ON HOW EXTENSIVE CLOUDS WILL BE THROUGH AFTERNOON. A BROKEN DECK IS A POSSIBILITY BUT SHOULD REMAIN JUST ABOVE MVFR CRITERIA. WINDS WILL INCREASE THIS AFTERNOON FROM THE NORTH AND VEER TO A NORTHEASTERLY DIRECTION BY EVENING. GUSTS OVER 20 KNOTS ARE EXPECTED FROM LATE MORNING THROUGH MID AFTERNOON. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...BULLER LONG TERM...BRB AVIATION...BRB
AREA FORECAST DISCUSSION
NWS BILLINGS MT
906 AM MDT THU SEP 19 2013 .UPDATE... WEAK SHORTWAVE IN NW FLOW ALOFT IS INTERACTING WITH SHALLOW BUT MOIST LOW LEVEL INSTABILITY TO PRODUCE AREAS OF LIGHT SHOWERS OR SPRINKLES FROM NEAR COLUMBUS EAST. IN FACT...CONVERGENT BAND HAS DEVELOPED DOWNWIND OF THE SNOWIES...THUS THE LIGHT SHOWERS IN THE BILLINGS AREA AT 9AM WITH A VEERED-TO-NORTH WIND. THIS ACTIVITY SHOULD END BY NOON IN OUR WEST...BUT STRONGER ASCENT AND DEEPER MOISTURE WILL IMPACT OUR EAST INTO THE AFTERNOON. RAP/NAM SOUNDINGS SHOW MOIST LOW LEVELS PERSISTING THRU THE AFTERNOON. HAVE THUS RAISED AND EXPANDED POPS FROM MILES CITY TO BAKER AND EKALAKA...AND DROPPED TEMPS JUST A BIT. PRECIP AMOUNTS WILL BE LIGHT BUT SHOULD AMOUNT TO A FEW HUNDREDTHS. TEMP AT BAKER COULD STRUGGLE TO RISE ABOVE THE LOW 50S TODAY...ALONG WITH A BRISK NW WIND WITH GUSTS TO 30 MPH. EASILY THE COOLEST DAY WE HAVE SEEN IN A LONG TIME. JKL && .SHORT TERM...VALID FOR TDY AND FRI... UPPER TROUGH CROSSING THE REGION TONIGHT WILL CONTINUE TO EXERT ITS INFLUENCE OVER OUR FORECAST AREA WELL INTO THURSDAY... ESPECIALLY IN THE NORTHEAST ZONES. AS SUCH...SOME CHANGES HAVE BEEN MADE FOR TODAY FORECAST. EARLY THIS MORNING...THE MAIN 500MB COLD POOL WAS SITUATED OVER SOUTHWEST MONTANA. THERE WAS ANOTHER MID LEVEL COLD POOL OVER NORTH CENTRAL MONTANA AS WELL WITH AN ASSOCIATED FRONT PUSHING EAST/SOUTHEAST ACROSS MONTANA. THIS FEATURE WILL SLIP DOWN THROUGH OUR ZONES BY 6AM. THERE IS A CONSISTENT EFFORT FROM THE MODELS TO BRING IN A LOW CLOUD DECK BEHIND THIS FEATURE...THICKEST ACROSS CUTER AND FALLON COUNTIES. WHILE SOUNDINGS AND HRRR DATA PARTIALLY BREAK MILES CITY OUT OF THIS IN THE AFTERNOON...THEY SUGGEST BAKER AND FALLON COUNTY WILL PERSIST UNDER OVERCAST CONDITIONS AS LONG AS 6PM. THIS SCENARIO IS A NOTORIOUS FORECAST BUSTER FOR BAKER. UNLESS I SEE SOMETHING AT THE LAST MOMENT SUGGESTING OTHERWISE...I WILL PLAN TO LOWER TEMPERATURES QUITE A BIT IN THIS AREA. ANOTHER CHANGE...THOUGH MINOR...WAS IN REGARD TO A TROWEL FEATURE ON THE BACKSIDE OF THE TROUGH. THIS IS CURRENTLY GENERATING SOME PRECIPITATION ALONG THE FRONT RANGE AND NORTHWEST MOUNTAINS. CROSS SECTIONS SHOW SOME MODEST LIFT AND MOISTURE AS IT WORKS OVER OUR FORECAST AREA THIS MORNING. IT WILL HAVE TO BATTLE A BRISK DOWNSLOPE WIND...SO VIRGA AND SPRINKLES MAY BE THE MAIN OUTCOME. HOWEVER...I HAVE SPREAD SOME LOW POPS BACK TO THE WEST AS WELL AS A LITTLE FURTHER SOUTH INTO UPSLOPE AREAS NEAR THE BIG HORNS FOR THE FIRST HALF OF THE DAY. THE TROUGH AXIS WILL BE JUST EAST OF THE MONTANA/DAKOTA BORDER BY EVENING. SO WE SHOULD SEE DECREASING CLOUDS AND WIND. LOWS MAY DIP TO AROUND OR JUST BELOW AVERAGE FOR THIS TIME OF YEAR...MAKING IT ONE OF THE OVERALL COOLEST WE HAVE HAD SO FAR THIS SEPTEMBER. RIDGE BUILDS IN QUICKLY FOR TOMORROW WHICH WILL RESULT IN A NICE BUMP IN THE MERCURY. BT .LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED... EXTENDED MODELS IN GOOD AGREEMENT FOR THIS WEEKEND GOING INTO EARLY NEXT WEEK BUT DIVERGE WITH A LARGE SYSTEM ACROSS THE WESTERN STATES BY MID NEXT WEEK. RIDGE AND ITS AXIS SHIFT EAST SATURDAY AS AN UPPER LOW AND TROUGH MOVE ONTO THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA COAST. SOUTHWEST FLOW ALOFT WILL PREVAIL ALONG WITH ABOVE NORMAL TEMPERATURES AND A SLIGHT SHOWER/THUNDERSTORM CHANCE. THE TROUGH ALONG WITH A COLD FRONT MOVE THROUGH THE FORECAST AREA LATE SATURDAY NIGHT INTO SUNDAY MORNING BRINGING BETTER CHANCES FOR SHOWERS WITH COOLER AND MORE NORMAL TEMPERATURES FOR SUNDAY. FAST ZONAL FLOW ALOFT LOOKS IN STORE FOR MONDAY AND TUESDAY WITH MAINLY A DOWNSLOPE SURFACE FLOW KEEPING CONDITIONS DRY FOR THE LOWER ELEVATIONS WITH SHOWERS FOR THE MOUNTAINS. BY LATE TUESDAY INTO WEDNESDAY...AN UPPER LOW TAKES SHAPE ACROSS THE PACIFIC NORTHWEST. MODELS DIVERGE GREATLY FROM THAT POINT ONWARD. THE GFS TAKES THE LOW SOUTH INTO THE GREAT BASIN AREA WEDNESDAY AND THURSDAY WHILE THE ECMWF EJECTS THE LOW NORTHEAST ACROSS MONTANA BUT STILL KEEPING A TROUGH ACROSS THE CENTRAL AND NORTHERN ROCKIES. EITHER SCENARIO WILL BRING INCREASING CHANCES FOR PRECIP TO THE FORECAST AREA. HOWEVER...LOCATION AND AMOUNTS OF PRECIP ALONG WITH TEMPEATURES VARY QUITE A BIT DEPENDING ON MODEL. WILL KEEP CHANCE POPS FOR MID NEXT WEEK WITH HIGHEST CHANCES FOR THE MOUNTAINS ALONG WITH A TREND TO COOLER TEMPERATURES. HOOLEY && .AVIATION... EXPECT MOSTLY CLOUDY SKIES TODAY WITH VFR CONDITIONS PREVAILING. THE EXCEPTION WILL BE ISOLATED TO SCATTERED SHOWERS POSSIBLE ALONG AND NORTH OF A KLVM - KBIL - KBHK LINE TODAY WHICH WILL RESULT IN POSSIBLE MVFR CONDITIONS AT TIMES. MVFR TO IFR CONDITIONS WILL ALSO BE POSSIBLE AT TIMES DUE TO LOW CEILINGS FROM KMLS EASTWARD. GUSTY NORTHWEST WINDS WILL BE LIKELY EAST OF KBIL TOWARD KMLS TO THE DAKOTA BORDERS. CHURCH && .PRELIMINARY POINT TEMP/POPS... TDY FRI SAT SUN MON TUE WED ------------------------------------------------------- BIL 064 043/077 049/084 053/068 048/071 050/071 048/062 2/W 00/U 00/U 22/T 11/B 02/T 22/W LVM 064 035/078 043/083 046/065 042/068 045/068 045/054 0/B 00/U 00/U 22/T 11/B 12/T 23/W HDN 066 038/079 045/086 051/072 046/073 049/074 048/065 2/W 00/U 00/U 12/T 21/B 01/B 12/W MLS 059 042/075 048/084 054/073 050/075 052/074 050/068 6/W 00/U 00/U 22/T 21/U 11/B 12/W 4BQ 061 038/075 045/084 053/075 047/074 049/075 047/068 2/W 00/U 00/U 12/T 21/U 11/U 12/W BHK 055 037/072 044/080 050/075 047/073 048/074 047/069 6/W 00/U 00/U 12/T 21/U 11/U 12/W SHR 063 036/076 046/084 050/070 044/071 047/072 045/064 1/B 00/U 00/U 12/T 30/U 01/U 12/W && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
729 AM CDT THU SEP 19 2013 .AVIATION... 12Z TAFS FOR KOMA...KOFK...KLNK THE SURFACE COLD FRONT WILL MOVE THROUGH OFK BY MID MORNING AND OMA/LNK BY EARLY AFTERNOON. SCT SHRA AND ISO TSRA ARE EXPECTED WITH THE FRONT AT ALL 3 TAF SITES WITH SOME MVFR VISBY POSSIBLE...BUT CIGS ARE EXPECTED TO REMAIN ABOVE MVFR RANGE. WILL INCLUDE THUNDER AT ALL 3 SITES FOR A COUPLE OF HOURS...BUT THE MAJORITY OF THE TIME IT WILL LIKELY BE JUST SHOWERS. THE PRECIP WILL CLEAR OUT OF THE TAF SITES BY LATE AFTERNOON WITH SKIES CLEARING OVERNIGHT. && .PREV DISCUSSION... /ISSUED 251 AM CDT THU SEP 19 2013/ DISCUSSION... GLANCE AT REGIONAL RADAR ALREADY SHOWING LINE OF CONVECTION FIRING ALONG INTENSE SFC BAROCLINIC ZONE EXTENDING FROM ABOUT NRN MN TO NWRN KS. BNDRY IN ASSOCIATION WITH UPPER SHORTWAVE TROF MIGRATING ACROSS THE NRN PLAINS. AGEOSTROPHIC LIFT JUST AHEAD OF RELATIVELY DEEP FRONTOGENESIS BNDRY IS QUITE STOUT...PER RUC13. ALSO...STRONG UPPER LEVEL DIVG ASSOCIATE WITH RRQ OF JET MAX ALOFT CONTRIBUTING TO ENHANCEMENT OF SYNOPTIC LIFT AS WELL. SHORT TERM ISSUE IS TIMING THE FRONTAL PASSAGE/PCPN THRU THE CWA. REGIONAL RADAR WAS SHOWING AN OUTFLOW BNDRY ASSOCIATED WITH CLUSTER OF STORMS IN WRN NEB WAS QUICKLY PUSHING EAST...AND WILL PROBABLY REACH THE CWA IN THE NEXT COUPLE HOURS. AT ANY RATE...SFC WIND PROGS VIA TIME-SERIES INDICATE LEADING EDGE OF THE TRUE FRONT REACHING KOFK BY LATE MORNING...THEN EARLY AFTN AT KLNK AND KOMA...THUS APPROXIMATE TIME FRAME FOR FOR EXPECTED CONVECTION. MEANWHILE... PERSISTENT MOISTURE ADV INTO THE REGION THE LAST 24 HRS HAS CULMINATED IN A MOISTURE RICH ENVIRONMENT AS SEE BY PWS VALUES RANGING ANYWHERE FROM 160%-220% ABOVE NORM AHEAD OF THE FRONT. AT THIS POINT SUSPECT THAT PCPN INTENSITY WILL INCREASE THIS AFTN OVER SRN CWA WHERE THE RUC13 IS SHOWING PRECIP EFFICIENCY/WARM CLOUD DEPTH PEAKS. IMPROVING CONDITIONS THEN TONIGHT AS STABLE AIRMASS ENVELOPS THE REGION. IN CASE OF LINGERING PCPN ACTIVITY...WILL MAINTAIN TOKEN EVENING POPS SOUTH. EXCELLENT WEATHER ON TAP THIS WEEKEND IN RESPONSE TO UPPER RIDGE BUILDING OVER THE PLAINS. NEXT ROUND OF PCPN COMES SUNDAY NIGHT/MONDAY WHEN NEXT POTENT SHORTWAVE TROF EXITS THE ROCKIES AND SWEEPS ANOTHER COLD FRONT INTO THE CNTRL PLAINS. WITH GFS AND ECM IN AGREEMENT DECENT LLVL MOISTURE FEED PRECEDING THE FRONT...GENEROUS RAINFALL AMOUNTS WILL ONCE AGAIN BE POSSIBLE. DEE && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS BISMARCK ND
645 AM CDT THU SEP 19 2013 .UPDATE... ISSUED AT 645 AM CDT THU SEP 19 2013 NO SIGNIFICANT CHANGES WITH THIS UPDATE. THE FORECAST FOR THE REMAINDER OF THE DAY WAS BLENDED TO THE 10 UTC RAP AND 06 UTC NAM GIVEN THEIR GOOD HANDLE OF THE STRATUS FIELD THAT IS OVERTAKING THE AREA. DID LOWER HIGHS A FEW DEGREES FROM THE PREVIOUS FORECAST ALONG AND WEST OF HIGHWAY 83 AS LOW LEVEL COLD AIR ADVECTION AND CLOUD COVER WILL SIGNIFICANTLY LIMIT TEMPERATURE RECOVERY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 256 AM CDT THU SEP 19 2013 LATEST WATER VAPOR IMAGERY SHOWS A DRY SLOT COVERING MOST OF WESTERN AND CENTRAL NORTH DAKOTA THIS MORNING. UPPER LOW CIRCULATING OVER NORTHEAST MONTANA IS FORECAST TO SHIFT EAST INTO THE DEVILS LAKE AREA BY THURSDAY NIGHT. INSTABILITY SHOWERS WILL CONTINUE TO WRAP AROUND THE LOW AND SLIDE MAINLY ACROSS NORTHERN NORTH DAKOTA TODAY. HAVE REMOVED THE MENTION OF THUNDER WITH SOUNDINGS SHOWING A STABLE PATTERN ALONG WITH A HIGH RH FIELD IN THE H85-H7 LAYER. THE NAM/RUC H85 RH FIELD SHOWS A LARGE SHIELD OF CLOUDY SKIES MOVING SOUTHEAST FROM SOUTHERN SASKATCHEWAN AND NORTHEAST MONTANA. THIS IS VERIFIED ON THE FOG/STRATUS LOOP. PATCHY FOG WAS ALSO ACCOMPANYING THE STRATUS DECK. SOUNDINGS INDICATE BREEZY WINDS TODAY WITH THE STRONGEST WINDS IN THE SOUTHWEST...HOWEVER WILL NOT ISSUE A WIND ADVISORY AS WINDS ARE FORECAST TO REMAIN BELOW CRITERIA...AS MIXING WILL BE LIMITED DUE TO THE EXTENSIVE LOW LEVEL CLOUD COVER FORECAST TODAY. HIGHS WILL BE IN THE UPPER 50S WEST TO AROUND 70F FAR SOUTHEAST. WILL NEED TO MONITOR THE FAR SOUTHWEST FOR A POSSIBLE FROST ADVISORY FRIDAY MORNING AS CLEARING SKIES ARRIVE LATE THURSDAY NIGHT WITH HETTINGER POSSIBLY DOWN TO 35F FOR A LOW TEMPERATURE. ELSEWHERE...EXPECT A SLOW DECREASE IN CLOUDS FOR CENTRAL NORTH DAKOTA THURSDAY NIGHT WHICH WILL HELP TO KEEP OVERNIGHT LOWS IN THE LOWER 40S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 256 AM CDT THU SEP 19 2013 THE HIGHLIGHTS OF THE EXTENDED FORECAST ARE FROST POTENTIAL FRIDAY NIGHT AND THUNDERSTORMS SUNDAY NIGHT INTO MONDAY. THE 00 UTC GUIDANCE SUITE IS IN GOOD AGREEMENT ON COOL SURFACE HIGH PRESSURE ACROSS WESTERN AND CENTRAL NORTH DAKOTA ON FRIDAY. GIVEN LITTLE MIXING AND A COOL MORNING START...WIDESPREAD HIGHS IN THE LOW TO MID 60S ARE FORECAST...WHICH PERHAPS A FEW READINGS IN THE 50S ACROSS THE TURTLE MOUNTAINS AND JAMES RIVER VALLEY. SURFACE HIGH PRESSURE PROPAGATES INTO FAR WESTERN MINNESOTA FRIDAY NIGHT...WITH RETURN FLOW COMMENCING ACROSS WESTERN NORTH DAKOTA. HOWEVER...THE COOL DAYTIME TEMPERATURES FRIDAY SET THE STAGE FOR FROST POTENTIAL WITH WIDESPREAD LOWS IN THE 30S POSSIBLE FOR CENTRAL NORTH DAKOTA WHERE RETURN FLOW WILL NOT ESTABLISH ITSELF. THEREAFTER...TEMPERATURES TREND BACK TO NEAR TO SLIGHTLY ABOVE NORMAL WITH HIGHS IN THE 70S SATURDAY AND SUNDAY UNDER A HIGH AMPLITUDE UPPER LEVEL RIDGE. THE 00 UTC DETERMINISTIC MODELS ALL DEPICT A POTENT SHORTWAVE PROPAGATING INTO THE NORTHERN PLAINS SUNDAY NIGHT INTO MONDAY...WITH WIDESPREAD CONVECTION POSSIBLE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 645 AM CDT THU SEP 19 2013 LATEST SATELLITE AND SURFACE OBSERVATIONS SHOW MVFR/IFR CIGS ACROSS THE NORTHERN AERODROMES OF KISN/KMOT. ANOTHER AREA OF MVFR CIGS IN EASTERN MONTANA WILL SWEEP INTO KDIK BY 13Z...INTO KBIS BY AROUND 15Z...AND KJMS BY MID AFTERNOON. MVFR CIGS WILL BE LOCKED IN PLACE THROUGH 03Z FRIDAY WITH A GRADUAL RETURN TO VFR IN THE WEST BY 06Z AND CENTRAL BETWEEN 06Z AND 12Z FRIDAY. BREEZY NORTHWEST WINDS OF 15 TO 25 MPH CAN BE EXPECTED ACROSS WESTERN/CENTRAL NORTH DAKOTA TODAY. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AYD SHORT TERM...KS LONG TERM...AYD AVIATION...AYD
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
634 AM EDT THU SEP 19 2013 .SYNOPSIS... A SERIES OF UPPER LEVEL DISTURBANCES WILL RESULT IN A CHANCE OF SHOWERS AND THUNDERSTORMS TODAY INTO TONIGHT. SHOWERS AND THUNDERSTORMS WILL BECOME MORE WIDESPREAD FRIDAY AFTERNOON INTO FRIDAY NIGHT AS A COLD FRONT APPROACHES FROM THE WEST. SHOWERS AND A FEW THUNDERSTORMS WILL CONTINUE INTO SATURDAY BEFORE A DRIER AND COOLER AIRMASS SETTLES INTO THE REGION FOR THE FIRST PART OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A PERSISTENT MCV HAS BEEN PROGRESSING VERY SLOWLY SOUTHEAST ACROSS NORTHERN INDIANA THROUGH THE OVERNIGHT HOURS. SO FAR IT HAS NOT SHOWED TOO MAY SIGNS OF DISSIPATING OR EVEN WEAKENING AND THE LAST SEVERAL RUNS OF THE HRRR HAVE BEEN CONSISTENTLY TRYING TO PUSH IT SOUTHEAST INTO OUR AREA THROUGH MID MORNING. THE AIRMASS ACROSS OUR AREA IS MORE STABLE WITH THE INSTABILITY GRADIENT DROPPING OFF FAIRLY QUICKLY ACROSS EASTERN INDIANA INTO WESTERN OHIO. AS A RESULT..WOULD EXPECT THE BETTER CHANCE OF THUNDERSTORM MAINTENANCE TO WORK MORE TO THE SOUTH AND STAY WEST OF MOST OF OUR AREA THROUGH THE MORNING HOURS. HOWEVER...THE 850-300 MB MEAN WIND IS MORE WESTERLY ACROSS NORTHERN INDIANA...BECOMING SOUTHEASTERLY ACROSS OUR AREA. THIS WOULD SUGGEST A DECENT CHANCE THAT SOME OF THE SHOWER ACTIVITY WILL WORK ITS WAY INTO AT LEAST THE WESTERN HALF OF OUR FA OVER THE NEXT SEVERAL HOURS. MEANWHILE...ABUNDANT LOW LEVEL MOISTURE ACROSS OUR AREA HAS ALLOWED FOR SOME FAIRLY WIDESPREAD STRATUS DEVELOPMENT ACROSS ABOUT THE SOUTHEAST TWO THIRDS OF OUR FA. WITH THE LOW LEVELS REMAINING MIXY THROUGH DAYBREAK...WOULD NORMALLY NOT BE SURPRISED TO SEE THE STRATUS EXPAND A LITTLE MORE...BUT THE DEBRIS CLOUDS FROM THE MCV MAY MITIGATE THIS TO SOME DEGREE. EITHER WAY...THE COMBINATION OF THE DEBRIS CLOUDS AND STRATUS DECK SHOULD KEEP US MAINLY CLOUD THROUGH THE MORNING HOURS. THIS MAY ALSO HAVE AN IMPACT ON TEMPERATURES AND HOW WELL WE DESTABILIZE THROUGH THIS AFTERNOON. IN THE WESTERLY TO SOUTHWESTERLY LOW LEVEL WAA PATTERN...WOULD EXPECT TO SEE SOME DECENT EROSION/DISSIPATION OF THE LOWER CLOUDS THROUGH LATE MORNING/EARLY AFTERNOON WHICH SHOULD EVENTUALLY ALLOW FOR PARTLY SUNNY SKIES. WILL NUDGE DOWN HIGHS JUST A TAD...GENERALLY RANGING FROM UPPER 70S EAST TO LOWER 80S WEST. THIS WOULD STILL ALLOW US TO DESTABILIZE THROUGH THIS AFTERNOON WITH ML CAPES PUSHING UP CLOSE TO 1000 J/KG. AS A RESULT...WILL GO AHEAD AND ALLOW FOR SOME CHANCE POPS ACROSS MUCH OF THE AREA THROUGH THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... THE 00Z NAM/GFS AND CMC ARE ALL TRYING TO HINT AT SOME SORT OF CONTINUING PCPN OR REDEVELOPMENT TONIGHT SOMEWHERE ACROSS OUR AREA WHILE THE 00Z ECMWF IS DRY. IT DOES LOOK LIKE WE COULD BE ON THE EDGE OF A SOUTHWEST TO NORTHEAST ORIENTED 925-850 MB LOW LEVEL JET LATER TONIGHT AND THIS COULD SERVE AS A FOCUSING MECHANISM. AS A RESULT..WILL HANG ON TO SOME LOWER END POPS...BUT CONFIDENCE IS NOT ALL THAT HIGH. A COLD FRONT WILL MOVE ACROSS THE AREA FRIDAY NIGHT. AHEAD OF THIS...WE SHOULD WARM UP FAIRLY WELL THROUGH THE DAY WITH HIGHS PUSHING UP INTO THE LOW TO MID 80S. THIS WILL ALLOW US TO DESTABILIZE ONCE AGAIN WITH MLCAPES AGAIN UP CLOSE TO 1000 J/KG. THIS SHOULD LEAD TO SOME SCATTERED PRE FRONTAL SHOWERS AND THUNDERSTORMS THROUGH THE DAY. BETTER LOW LEVEL CONVERGENCE JUST AHEAD OF THE FRONT WILL PUSH INTO OUR NORTHWEST LATE FRIDAY AFTERNOON AND THEN PROGRESS SOUTHEAST ACROSS OUR AREA THROUGH FRIDAY EVENING. THIS WILL ALLOW FOR A MORE ORGANIZED LINE OF SHOWERS AND THUNDERSTORMS. DEEP LAYER SHEAR IS NOT TERRIBLY STRONG INITIALLY WITH THE PCPN FRIDAY AFTERNOON/FRIDAY EVENING...BUT THE 0-3 KM SHEAR VALUES DO PUSH UP INTO THE 25 TO 30 KNOT RANGE. THIS MAY BE ENOUGH TO SUPPORT SOME MARGINALLY SEVERE STORMS LATE FRIDAY AFTERNOON INTO FRIDAY EVENING....ESPECIALLY ACROSS OUR NORTHWEST. AS THE FRONT PUSHES OFF TO THE SOUTHEAST...EXPECT PCPN TO TAPER OFF FROM NORTHWEST TO SOUTHEAST DURING THE DAY ON SATURDAY. HIGH PRESSURE AND A COOLER AIRMASS WILL BUILD INTO THE AREA THROUGH THE LATER PART OF THE WEEKEND. HIGHS ON SATURDAY WILL BE IN THE 70-75 DEGREE RANGE WITH HIGHS ON SUNDAY IN THE UPPER 60S TO NEAR 70. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... ON MONDAY...HIGH PRESSURE WILL BUILD IN FROM THE NORTH. COULD SEE ENOUGH MOISTURE FROM THE LOW MOVING UP THE COAST TO PRODUCE ISOLATED SHOWERS IN THE EXTREME EAST. AFTER MONDAY...SURFACE HIGH PRESSURE EXTENDING INTO THE REGION FROM THE NE WILL BRING DRY WEATHER AND MILD TEMPERATURES. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... UNSETTLED WEATHER CONDITIONS WILL CONTINUE THROUGH THE NEXT SEVERAL DAYS UNTIL A COLD FRONT PUSHES THROUGH SATURDAY MORNING. MOISTURE CONTINUES TO INCREASE OVER THE OHIO VALLEY...RESULTING IN INCREASING CLOUDS...SHOWERS AND A FEW THUNDERSTORMS. THE SHOWER AND THUNDERSTORM COMPLEX WHICH ORIGINATED OVER NORTHERN ILLINOIS LATE YESTERDAY EVENING CONTINUES TO PUSH SOUTHEAST AND IS CURRENTLY LOCATED OVER CENTRAL INDIANA AND WEST CENTRAL OHIO. THIS PRECIPITATION COMPLEX IS EXPECTED TO MOVE THROUGH THE AREA THIS MORNING AND EARLY AFTERNOON. THERE IS A RISK OF THUNDERSTORMS WITH THIS COMPLEX OVER THE WESTERN TAF SITES AND THIS HAS BEEN INCLUDED IN THE FORECAST. AHEAD OF THIS AREA CONDITIONS ARE IFR DUE TO FOG AND STRATUS. AS THE PRECIPITATION MOVES INTO THESE AREAS THE IFR CONDITIONS SHOULD IMPROVE RAPIDLY. IN THE RAIN AREAS AFTER THE IFR CONDITIONS HAVE IMPROVED EXPECT VFR WITH MVFR CIGS AND VSBY IN THE HEAVIER SHOWERS AND THUNDERSTORMS. ONCE THESE CONDITIONS MOVE TO THE EAST AND SOUTHEAST OF THE FORECAST AREA THERE SHOULD BE A SIGNIFICANT BREAK WHERE VFR CONDITIONS DOMINATE THE FORECAST AREA WELL INTO THE NIGHTTIME HOURS. THEN FOG AND POSSIBLE STRATUS ONCE AGAIN WILL RETURN. THESE CONDITIONS ARE MENTIONED IN THE FORECAST BUT TIMING AND AREAL EXTENT OF COVERAGE WILL HAVE TO BE FINE TUNED IN LATER FORECASTS. OUTLOOK...THUNDERSTORMS WILL BE POSSIBLE FROM FRIDAY AFTERNOON THROUGH SATURDAY MORNING. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...JGL NEAR TERM...JGL SHORT TERM...JGL LONG TERM...PARKER AVIATION...HAYDU
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
607 AM EDT THU SEP 19 2013 .SYNOPSIS... HIGH PRESSURE CENTERED OVER EASTERN PENNSYLVANIA TODAY WILL SLIDE OFF THE EAST COAST FRIDAY. A COLD FRONT WILL PUSH EAST ACROSS THE STATE SATURDAY AND SATURDAY NIGHT. ANOTHER SLOW MOVING HIGH PRESSURE SYSTEM WILL THEN BUILD INTO THE REGION SUNDAY AND REMAIN OVER THE AREA THROUGH MUCH OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... SATELLITE SHOWS AN EXPANDING AREA OF STRATOCU ACROSS WESTERN PA EARLY THIS AM...THE RESULT OF COOLING/MOISTENING BLYR BENEATH A STRONG SUBSIDENCE INVERSION. SATL TRENDS SUGGEST ROUGHLY THE WESTERN HALF OF THE STATE WILL BE COVERED BY THIS DECK OF LOW CLOUDS BY 12Z. WHERE SKIES HAVE REMAINED CLEAR...MODIS 11-3.7UM IMAGERY SHOWS FOG HAS DEVELOPED IN THE VALLEYS OF NORTH CENTRAL PA. THE PATCHY FOG ACROSS THE EASTERN HALF OF THE STATE SHOULD BURN OFF BY ARND 13Z BASED ON LATEST 3KM HRRR SFC RH. FURTHER WEST...ARRIVAL OF MUCH HIGHER DWPTS WILL RESULT IN ONLY SLOW CLEARING FROM EARLY AM STRATOCU. EXPECT THE LOWS CLOUDS TO LIFT AND BREAK UP TO A BKN CU FIELD BY AFTN ACROSS THE W MTNS. GEFS MEAN 925MB TEMPS SUPPORT MAX TEMPS THIS AFTN IN THE L/M70S...WITH THE WARMEST TEMPS RELATIVE TO NORMAL ACROSS THE W MTNS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... A MAINLY CLEAR SKY AND LIGHT WINDS SHOULD LEAD TO PATCHY VALLEY FOG LATE TONIGHT. INCREASING LOW LVL MOISTURE ON A LIGHT SOUTHERLY FLOW SHOULD LEAD TO A MILDER NIGHT WITH MINS FROM THE U40S TO L50S MOST LOCATIONS. AN INCREASING SSW FLOW AHEAD OF SHORTWAVE DIVING INTO THE GRT LKS WILL PUSH PWATS AND 8H TEMPS WELL ABV SEASONAL NORMS ACROSS WESTERN PA FRIDAY. DIURNAL HEATING OF THIS AIR MASS SHOULD RESULT IN MARGINAL INSTABILITY ACROSS THE W MTNS BY LATE IN THE DAY...POSSIBLY SUPPORTING DEVELOPMENT OF A FEW PM TSRA ACROSS THE ALLEGHENY PLATEAU. SKIES SHOULD RANGE FROM PTSUNNY ACROSS THE W MTNS...TO SUNNY E OF THE SUSQ RIVER...WHERE LOWER PWAT AIR WILL LINGER. GEFS MEAN 925 TEMPS RISE ABOUT 2C FROM THOSE OF TDY...SUPPORTING MAX TEMPS BTWN 75-80F. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... FAIRLY MINOR TIMING DIFFS WITH RESPECT TO FROPA SAT/SAT NIGHT. LATEST GEFS/SREF AND OPER RUNS SUPPORT RAINFALL BTWN 0.5 AND ONE INCH OVR MUCH OF THE AREA WITH LOCALLY HIGHER AMTS POSS...AS PLUME OF ANOMALOUS PWATS WITH GULF OF MEX CONNECTION WORKS ACROSS THE AREA AHEAD OF CDFRONT. ABUNDANT PRE-FRONTAL CLOUD COVER INDICATED BY MDL 850-500RH FIELDS AND THIS IS REFLECTED BY PRETTY MEAGER CAPES SAT AFTN...BUT WILL MAINTAIN SLIGHT CHC OF TSRA FOR NOW. BY SUNDAY...A MORE PROGRESSIVE UPPER AIR PATTERN IS NOW INDICATED THAN A DAY AGO...WITH BULK OF MDL DATA PUSHING CDFRONT EAST OF THE REGION BY EARLY SUNDAY. HAVE TRIMMED POPS BUT KEPT SLIGHT CHC IN THE FCST FOR SUNDAY TO ACCOUNT FOR HANDFUL OF GEFS MEMBERS WHICH STILL DEVELOP WAVE ON FRONT AND KEEP SHRA GOING ACROSS EASTERN PA SUNDAY. A TRANQUIL WX PATTERN APPEARS TO BE IN STORE FOR CENTRAL PA NEXT WEEK...AS NEARLY ALL MED RANGE MDL DATA KEEP CENTRAL PA UNDER THE INFLUENCE OF HIGH PRES AND DRY NORTHERLY FLOW. 925-850MB TEMPS INDICATE DAYTIME TEMPS SHOULD BE CLOSE TO NORMAL FOR LATE SEPT...ALTHOUGH SOME COOL NIGHTS APPEAR LIKELY DUE TO DRY AIR AND PROXIMITY OF SFC HIGH. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... LIGHT SOUTHERLY FLOW PUSHING AN AREA OF INCREASED LOW LEVEL MOISTURE NORTHWARD ACROSS W PA. AN AREA OF MVFR CIGS ASSOCIATED WITH THIS FEATURE WILL WORK INTO KJST-KAOO-KFIG-KBFD DURING THE PREDAWN HOURS...WITH CIGS DIPPING TO IFR AT KJST FOR A FEW HOURS BEFORE SUNRISE IN UPSLOPE FLOW. ELSEWHERE...VFR CONDITIONS WILL CONTINUE EXCEPT FOR LOCALIZED VALLEY FOG. LOWER CIGS ACROSS PORTIONS OF THE WEST WILL IMPROVE TO VFR SHORTLY AFTER SUNRISE AS LAYER MIXES...LEAVING A VFR DAY AREAWIDE. CIG RESTRICTIONS AGAIN LIKELY EARLY FRI MORNING ACROSS THE WEST AS INCREASING LOW LEVEL SOUTHWEST FLOW CONTINUES MOISTURE TRANSPORT INTO THE REGION. OUTLOOK... FRI...PATCHY AM FOG POSS. OCNL MVFR CIGS ALSO POSS AT KJST-KBFD IN SCT SHRA/TSRA DURING THE DAY. ELSEWHERE...MAINLY VFR. FRI NIGHT...PATCHY FOG. LOWERING CIGS ACROSS THE WEST WITH SHOWERS DEVELOPING AS COLD FRONT APPROACHES. SAT-SAT NIGHT...COLD FRONT CROSSES REGION. RAIN AND SCT TSTMS WILL BRING RESTRICTIONS AREAWIDE. SUN...MVFR CONTINUES IN SCT SHRA/TSRA...ESP SE. MON...NO SIG WX. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD AVIATION...LAMBERT/CERU
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
1039 AM CDT THU SEP 19 2013 .DISCUSSION...12Z UPPER AIR ANALYSIS PLACES AN UPPER LEVEL RIDGE AXIS OVER THE SOUTHEAST UNITED STATES THIS MORNING. CONSEQUENTLY...RAIN FREE WEATHER IS OCCURRING ACROSS THE MID SOUTH WITH ANY CONVECTIVE ACTIVITY OCCURRING THUS FAR OVER THE OHIO VALLEY AND PORTIONS OF THE UPPER MID WEST AND NORTHERN/CENTRAL PLAINS. AS OF 10 AM CDT...TEMPERATURES ARE IN THE UPPER 70S TO AROUND 80 DEGREES AT MOST LOCATIONS. LATEST SHORT TERM MODEL TRENDS INDICATE THE POTENTIAL FOR SOME ISOLATED TO PERHAPS SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP FROM DAYTIME HEATING ACROSS PORTIONS OF THE MID SOUTH...MAINLY ALONG AND WEST OF THE MISSISSIPPI RIVER WHERE BETTER LOW LEVEL MOISTURE RESIDES. AT THIS TIME...FEEL THE LATEST 3KM HRRR AND RUC MAY BE HANDLING THE CONVECTIVE POTENTIAL THE BEST. WILL UPDATE FORECAST TO ADJUST POPS ACCORDINGLY...AND MAKE ADJUSTMENTS TO TEMPERATURES...CLOUD COVER AND ALL OTHER ELEMENTS AS NEEDED. UPDATED GRIDS WILL BE AVAILABLE SHORTLY. CJC && .PREV DISCUSSION... /ISSUED 709 AM CDT THU SEP 19 2013/ DISCUSSION... UPDATED FOR 12Z AVIATION DISCUSSION PREV DISCUSSION... /ISSUED 350 AM CDT THU SEP 19 2013/ SKIES ARE MOSTLY CLEAR ACROSS MUCH OF THE FORECAST AREA THIS MORNING WITH TEMPERATURES RANGING FROM THE MID 60S TO MID 70S. TODAY SHOULD BE FAIRLY SIMILAR TO YESTERDAY WITH SOME SCATTERED THUNDERSTORMS FORMING MAINLY DURING THE AFTERNOON HOURS ACROSS THE NORTHERN HALF OF THE FORECAST AREA. TEMPERATURES WILL REMAIN QUITE WARM AGAIN TODAY WITH HIGHS IN THE MID 80S TO AROUND 90 DEGREES. BY TONIGHT...A COLD FRONT WILL BE MOVING THROUGH THE CENTRAL PLAINS AND INTO SOUTHWEST MISSOURI. AHEAD OF THE FRONT SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP WITH SOME OF THIS ACTIVITY REACHING MAINLY WESTERN SECTIONS OF THE FORECAST AREA. ON FRIDAY THE COLD FRONT WILL START MOVING THROUGH ARKANSAS SO THE CHANCE OF RAIN WILL INCREASE OVER THE FORECAST AREA WITH THE BEST CHANCE OF THUNDERSTORMS WEST OF THE MISSISSIPPI RIVER. THIS MODEL RUN SEEMS TO BRING THE COLD FRONT THROUGH THE FORECAST AREA FASTER THAN PREVIOUS RUNS SO THAT THE FRONT WILL BE JUST ABOUT OUT OF THE REGION BY SATURDAY MORNING. FRIDAY NIGHT SHOULD BE QUITE WET AS THE FRONT MOVES THROUGH. ON SATURDAY RAIN CHANCES WILL DIMINISH FROM NORTHWEST TO SOUTHEAST AS COOLER AND DRIER AIR BEGIN TO MOVE IN. TEMPERATURES ON SATURDAY WILL BE A FEW DEGREES COOLER THAN NORMAL WITH HIGHS AROUND 80 DEGREES EXPECTED FOR MUCH OF THE FORECAST AREA. BY SATURDAY NIGHT...THE EXTREME SOUTHEAST CORNER OF THE FORECAST AREA IS THE ONLY AREA THAT MIGHT SEE AN ISOLATED SHOWER. BY SUNDAY HIGH PRESSURE WILL IN CONTROL OF THE WEATHER FOR MUCH OF THE EASTERN U.S. INCLUDING THE FORECAST AREA. THIS WILL MEAN ANOTHER PERIOD OF DRY WEATHER FROM SUNDAY THROUGH WEDNESDAY. TEMPERATURES WILL REMAIN SLIGHTLY BELOW NORMAL SUNDAY AND MONDAY BUT WINDS SHOULD BEGIN TO SHIFT TO THE SOUTH BY TUESDAY ALLOWING FOR WARMER AIR TO RETURN TO THE REGION WITH ABOVE NORMAL TEMPERATURES EXPECTED FOR TUESDAY AND WEDNESDAY. ARS && .AVIATION... 12Z TAF CYCLE VFR CONDS WILL PREVAIL THROUGHOUT THE PERIOD. EXPECT A FEW SHRAS AND TSRAS TO DEVELOP ACROSS NORTHERN SECTIONS THIS AFTN. CONSIDERING THE LATEST INFO AND WHAT HAPPENED YESTERDAY NOT CONFIDENT ENOUGH IN THE AMOUNT OF COVERAGE TO PLACE THE MENTION OF VCTS AT ANY OF THE TAF SITES. WL INCLUDE A MENTION OF VCSH AT KJBR AND KMKL. WINDS WILL BE SOUTH AT 8-12 KTS TODAY. TONIGHT...SHRAS IN ADVANCE OF A COLD FRONT MAY BEGIN MOVING INTO KJBR BY THE END OF THE PERIOD. WINDS OVERNIGHT WILL BE SOUTH AT 3-8 KTS. SJM && .PRELIMINARY POINT TEMPS/POPS... MEM 90 72 85 68 / 20 30 70 70 MKL 89 68 85 64 / 20 20 70 70 JBR 89 71 82 63 / 30 30 80 50 TUP 89 68 88 70 / 10 10 40 80 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. && $$
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
851 AM CDT THU SEP 19 2013 .UPDATE... WARM FRONT WILL CONTINUE TO LIFT NORTHWARD AND AWAY FROM TN TODAY. MEANWHILE...SFC HIGH WILL ALSO CONTINUE TO MOVE EAST TOWARD THE ATLANTIC COAST. NO APPRECIABLE UPPER DYNAMICS ARE APPARENT AS THE UPPER RIDGE AXIS WILL ACTUALLY BE IN CLOSER PROXIMITY TO THE MID STATE BY LATE THIS AFTERNOON. HOWEVER...SOME WEAK BUT FAVORABLE CURVATURE AND SHEAR WILL ROTATE ACROSS PORTIONS OF THE AXIS LATER TODAY. THIS ALL TRANSLATES INTO A SLIGHT CHANCE OF SHOWERS OR TSTMS ACROSS NORTHERN AREAS. TEMPERATURES SHOULD BE A FEW DEGREES GREATER THAN YESTERDAY. THUS...UPPER 80S FOR HIGHS STILL LOOKS REASONABLE. HRRR IN LINE WITH CURRENT FCST THINKING. ONLY MOD WILL BE TO RERUN ZONES WHICH WILL AUTOMATICALLY REMOVE THE PATCHY FOG WORDING. && .PREV DISCUSSION... /ISSUED 614 AM CDT THU SEP 19 2013/ UPDATE...FOR AVIATION. AVIATION... 12Z TAFS...VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THIS PERIOD...THE ONLY EXCEPTION WILL BE SOME POSSIBLE EARLY MORNING MVFR FOG. SURFACE HIGH PRESSURE ALONG THE EAST COAST WILL PRODUCE A SOUTH FLOW INTO MID TN WITH SCT-BKN CLOUDS. A STRAY SHRA/TSRA CANNOT BE RULED OUT...BUT PROB TOO LOW TO INCUDE IN TAFS. 13 PREV DISCUSSION... /ISSUED 355 AM CDT THU SEP 19 2013/ DISCUSSION... FORECAST REASONING WILL LEAN TOWARD A CONSENSUS MODEL SOLUTION COMPROMISE FOR THE FORECAST PERIOD UNLESS OTHERWISE NOTED. FORECAST QUANDARIES...PATCHY FOG POTENTIAL THRU THE MID MORNING HRS TODAY...SHWR/TSTM CHANCES ESPECIALLY IN ASSOCIATION WITH FRONTAL PASSAGE FRI NIGHT INTO SAT ALONG WITH POTENTIAL OF THIS BRINGING HEAVY RAINFALL TO THE MID STATE...OVERALL WX PATTERN SAT NIGHT INTO THE FIRST PART OF NEXT WEEK...AND TEMPS. WITH MOST OF THE MID STATE EXPERIENCING CLR SKIES THIS MORNING...AND WITH TEMPS/DEWPOINTS MAINLY IN THE LOW TO MID 60S ALONG WITH CALM WINDS...DO EXPECT SOME PATCHY FOG TO FORM IN THE USUAL FOG PRONE LOCATIONS AND NEAR BODIES OF WATER AND LAST THRU THE MID MORNING HRS. OTHERWISE...WITH RIDGING INFLUENCES STILL DEPICTED BY MODEL CONSENSUS TO BECOME A LITTLE BIT MORE ENHANCED THRU THE MORNING HRS ON FRI...WILL ONLY INTRODUCE A SLIGHT CHANCE OF SHWRS LATE MORNING WITH A SLIGHT CHANCE OF SHWRS/TSTMS BY THE AFTERNOON HRS WITH AFTERNOON HIGH TEMPS BEING AROUND 5 DEGREES OR SO ABOVE SEASONABLE NORMAL VALUES UNDER PTCLDY SKIES. HIGHS WILL BE IN THE MID TO UPPER 80S... LOWER 80S PLATEAU. WILL KEEP THE MID STATE DRY TONIGHT AGAIN UNDER PTCDLY SKIES WITH THE POSSIBILITY OF YET AGAIN PATCHY FOG ACROSS USUAL FOG PRONE LOCATIONS AND NEAR BODIES OF WATER THRU THE EARLY MORNING HRS...WITH A SLIGHT CHANCE OF SHWRS/TSTMS ACROSS WRN PORTIONS OF THE MID STATE THRU THE MID FRI MORNING HRS WITH THAT PATCHY FOG CONTINUING ACROSS CNTRL AND ERN PORTIONS OF THE MID STATE DURING THIS TIME PERIOD ALSO. LOWS TONIGHT ARE EXPECTED TO BE IN THE LOW TO MID 60S...AROUND 60 PLATEAU. STILL LOOKS LIKE A PRONOUNCED UPPER LEVEL TROUGH WILL DEVELOP TO OUR W IN ASSOCIATION WITH A SFC COLD FRONT...WITH THEN BOTH APPROACH FRI NIGHT AND THEN MOVE ACROSS THE MID STATE AS THE DAY PROGRESSES ON SAT. GFS SHOWING A LITTLE BIT MORE ENHANCED LOW LEVEL JET DYNAMICS MAINLY ACROSS SRN AND ERN/PLATEAU PORTIONS OF THE MID STATE BY SAT MORNING WITH PRECIP WATER AMOUNTS APPROACHING AND EVEN SLIGHTLY OVER TWO INCHES. IN LOOKING AT OTHER FORECAST SOUNDINGS...GFS THE MOST AGGRESSIVE HERE WITH PRECIP WATER VALUES ALONG WITH THE ABOVE MENTIONED LOW LEVEL JET STRUCTURE AND THUS PRODUCING SOME HIGH QPF VALUES FOR THE MID STATE FRI NIGHT INTO THE FIRST HALF OF SAT. IN LOOKING AT LATEST WPC QPF FORECAST ALONG WITH THE OTHER MODELS...AM AT THIS TIME INCLINED TO BE A LITTLE CONSERVATIVE HERE AS THIS SYSTEM IS NOT EXPECTED TO BRING A SIGNIFICANT FORCING...INSTABILITY...OR TEMP AIRMASS CONTRAST WITH IT...THUS WILL GO WITH SLIGHTLY LOWER QPF VALUES THRU THIS TIME PERIOD. HOWEVER...CAN NOT RULE OUT THE HEAVY RAINFALL POTENTIAL... BUT THINK AT THIS TIME THAT ANY TYPE OF FLOODING WOULD BE LOCALIZED AND MINOR AT BEST PER HIGH FFG VALUES AND RAINFALL NOT HAVING BEEN RECEIVED OVER WIDE AREAS DURING THE PAST FEW DAYS AND WHAT IS EXPECTED TO HAPPEN UP UNTIL FRI NIGHT. HOWEVER...TO GIVE A HEADS UP POTENTIAL ON THIS HEAVY RAINFALL POSSIBILITY...WILL GO AHEAD AND MENTION IN THE MORNING`S HWO ISSUANCE. OTHERWISE...HAVE MENTIONED INCREASING CHANCES OF SHWR/TSTMS E TO W AS THE DAY PROGRESSES ON FRI WITH THE ABOVE MENTIONED LIMITED INSTABILITY KEEPING ONLY A CHANCE OF TSTMS THRU FRI NIGHT INTO SAT. HAVE INCREASED POPS TO CAT MOST LOCATIONS AFTER MIDNIGHT FRI NIGHT...LIKELY S AND PLATEAU...AND WILL CONTINUE THE TREND OF DECREASING CHANCES OF SHWRS/TSTMS W TO E AS THE DAY PROGRESSES ON SAT. HIGHS ON FRI WILL CONTINUE THE TREND OF 5 DEGREES OR SO ABOVE SEASONABLE NORMAL VALUES WITH LOWS FRI NIGHT MAINLY IN THE LOW TO UPPER 60S...WITH HIGHS ON SAT...AS THE FRONT MOVES THRU ALONG WITH THE UPPER LEVEL TROUGH...NEAR OR ACTUALLY BELOW SEASONABLE NORMAL VALUES WITH HIGHS MAINLY IN THE MID TO UPPER 70S. AS FOR SAT NIGHT INTO THE MID PORTION OF NEXT WEEK...THRU THE FIRST PART OF NEXT WEEK...WILL TREND CLOSE TO CURRENT FORECAST REASONING WITH A SLIGHT CHANCE TO CHANCE OF SHWRS ACROSS AT LEAST ERN AND PLATEAU COUNTIES SAT NIGHT...BUT AM LEANING TOWARD KEEPING THE MID STATE DRY ON SUN WITH RIDGING INFLUENCES BUILDING ACROSS THE MID STATE PROVIDING DRY CONDITIONS AND A RETURN TOWARD TEMPS NEAR SEASONABLE NORMS. EVEN THOUGH THERE ARE SOME TIMING DIFFERENCES IN MODELS...UNLIKE AT THIS TIME YESTERDAY...IT DOES NOT LOOK LIKE ANY OF THE MODELS ARE ADVERTISING ANY TYPE OF CLOSED UPPER LEVEL LOW DEVELOPMENT BEHIND THE ABOVE MENTIONED FRONTAL SYSTEM THAT WOULD SUBSTANTIALLY AFFECT THE MID STATE. THE LATEST EURO DOES DEVELOP A CLOSED LOW ACROSS CNTRL MS BY MON MORNING BUT MOVES IT WELL SOUTH OF THE MID STATE AND THEN OPENS IT UP BY TUE...POSSIBLY BRINGING SOME WRAP AROUND ADDITIONAL MOISTURE TO THE MID STATE DURING THE FIRST PART OF NEXT WEEK. WITH THIS OVERALL...AND MORE LIKELY TO OCCUR...CHANGE IN CONSENSUS MODEL SOLUTIONS...WILL GO CLOSE TO CURRENT FORECASTED WX CONDITIONS ACROSS THE MID STATE DURING THIS TIME PERIOD. 31 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 21
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
619 AM CDT THU SEP 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 317 AM CDT THU SEP 19 2013 MAIN FORECAST CONCERNS ARE ON SHOWERS AND THUNDERSTORMS TODAY INTO TONIGHT WITH THE POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING. LATEST WATER VAPOR IMAGERY SHOWED A TROUGH DIGGING INTO THE EASTERN DAKOTAS AND CENTRAL PLAINS...PUSHING EAST TOWARD THE UPPER MISSISSIPPI RIVER VALLEY. SEVERAL WEAK EMBEDDED SHORTWAVES NOTED IN SOUTHWEST FLOW OVER THE REGION THIS MORNING. SURFACE OBSERVATIONS PLACED A COLD FRONT OVER THE EASTERN DAKOTAS MOVING EAST. SHOWERS AND ISOLATED THUNDERSTORMS WERE OCCURRING EARLY THIS MORNING MAINLY SOUTH OF INTERSTATE 90. THE COLD FRONT WILL MOVE INTO THE UPPER MISSISSIPPI RIVER VALLEY TODAY BRINGING SHOWERS AND THUNDERSTORMS TO THE AREA. MLCAPE VALUES INCREASE TO 1500 TO 2200 J/KG THIS AFTERNOON AHEAD OF THE COLD FRONT. 0-6 KM BULK SHEAR VALUES START OFF RATHER WEAK EARLY THIS AFTERNOON AS THE UPPER TROUGH AND JET STREAK ARE LOCATED WELL WELL WEST OF THE REGION. HOWEVER...THE TROUGH STARTS TO CATCH UP TO THE COLD FRONT DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. 0-6 KM SHEAR STARTS OUT IN THE 20 TO 25 KT RANGE EARLY THIS AFTERNOON AND THEN INCREASES TO 30 TO 40 KTS DURING THE EARLY EVENING HOURS. MOST OF THIS SHEAR IS LOCATED IN THE 0-3 KM LAYER WHICH WOULD FAVOR A LINEAR CONVECTIVE MODE WITH POSSIBLE BOWING SEGMENTS...CAPABLE OF PRODUCING DAMAGING WINDS. MESOSCALE MODELS SUCH AS THE SPCWRF AND HIRESARW EAST ARE IN AGREEMENT WITH THIS CONVECTIVE MODE. THE 0-3 KM SHEAR VECTOR IS INITIALLY ORIENTED PERPENDICULAR TO THE FRONT BUT THEN TURNS MORE PARALLEL TO IT. STORMS ALONG OR BEHIND THE FRONT COULD STRUGGLE TO ORGANIZE INTO LINEAR STRUCTURES IF THEY DEVELOP BEHIND THE LEADING WIND SHIFT OF THE FRONT. ALSO...CANNOT RULE OUT SOME MARGINALLY SEVERE HAIL WITH THIS ACTIVITY GIVEN THE HIGHER CAPE VALUES. SHOWERS AND STORMS WILL CONTINUE ACROSS MUCH OF THE AREA EARLY THIS EVENING THEN GRADUALLY SHIFT SOUTHEAST LATE TONIGHT AS THE COLD FRONT PROGRESSES EAST. SHOWERS AND THUNDERSTORMS WILL ALSO SHIFT SOUTHEAST AND EXIT THE AREA LATE TONIGHT INTO FRIDAY MORNING. PLAN ON AN UNSEASONABLY WARM DAY ACROSS THE AREA TODAY WITH WARM SOUTHERLY FLOW. LOOK FOR HIGH TEMPERATURES TO CLIMB INTO THE THE LOWER TO MID 80S BEFORE THE PRECIPITATION MOVES IN. CANNOT RULE OUT SOME UPPER 80S OVER NORTHEAST IOWA INTO SOUTHWEST WISCONSIN. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 317 AM CDT THU SEP 19 2013 THE UPPER LEVEL TROUGH SWINGS THROUGH THE FORECAST AREA ON FRIDAY PRODUCING STRATUS AND SOME STRATOCUMULUS DURING THE AFTERNOON HOURS...LEADING TO MOSTLY CLOUDY SKIES. FRIDAY WILL BE BREEZY WITH A TIGHT PRESSURE GRADIENT OVER THE REGION AS HIGH PRESSURE BUILDS IN FROM THE WEST. THE HIGH WILL THEN MOVE INTO THE AREA FRIDAY NIGHT INTO SATURDAY MORNING WITH DRY AND QUIET WEATHER EXPECTED. PLAN ON LOW TEMPERATURES FALLING INTO THE 40S FRIDAY NIGHT...WITH SOME UPPER 30S POSSIBLE OVER FAVORED COLD SPOTS ACROSS CENTRAL INTO NORTH CENTRAL WISCONSIN. THE HIGH WILL REMAIN OVER THE AREA THROUGH THE WEEKEND. HIGH TEMPERATURES ON SATURDAY WILL BE IN THE 60S...WITH OVERNIGHT LOWS FALLING INTO THE UPPER 30S TO LOWER 40S. THE COLDEST TEMPERATURES WILL BE ACROSS CENTRAL AND NORTH CENTRAL WISCONSIN WHERE SOME LOWER 30S ARE POSSIBLE. HAVE ADDED FROST TO THE FORECAST ACROSS THESE AREAS LATE SATURDAY NIGHT INTO EARLY SUNDAY MORNING. A FROST ADVISORY MAY BE NEEDED ALONG AND NORTH OF THE INTERSTATE 94 CORRIDOR. THE HIGH WILL START TO SLIDE EAST OF THE REGION SUNDAY INTO SUNDAY NIGHT AS A TROUGH DEVELOPS OVER THE PLAINS. SOUTH/SOUTHEAST FLOW WILL SET UP OVER THE REGION USHERING IN SLIGHTLY WARMER TEMPERATURES FOR SUNDAY. PLAN ON HIGHS IN THE UPPER 60S TO LOWER 70S. THE NEXT CHANCE FOR RAIN WILL BE MONDAY NIGHT INTO TUESDAY AS AN UPPER TROUGH SWINGS THROUGH THE UPPER MISSISSIPPI RIVER VALLEY FROM THE CENTRAL/NORTHERN PLAINS. SURFACE HIGH PRESSURE LOOKS TO HOLD STRONG OVER THE AREA AND MUCH OF THE PRECIPITATION THE FORECAST MODELS ARE SHOWING STARTS TO REALLY DRY UP AS THE TROUGH MOVES INTO THE HIGH. SOUTHERLY FLOW LOOKS TO CONTINUE OVER THE AREA THROUGH THE MIDDLE OF NEXT WEEK WITH MAINLY QUIET WEATHER EXPECTED AND TEMPERATURES HOLDING NEAR NORMAL WITH HIGHS IN THE 70S AND LOWS IN THE 50S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 619 AM CDT THU SEP 19 2013 SCATTERED CONVECTION KEEPS POPPING UP AROUND THE AREA THIS MORNING IN THE LOW LEVEL JET AND THE ISENTROPIC UP GLIDE OCCURRING ON THE 305K AND 310K SURFACES. THE 19.09Z RAP SUGGESTS THIS MOISTURE TRANSPORT AND ISENTROPIC UP GLIDE WILL START TO DIMINISH AFTER SUNRISE AND EXPECT THAT THE ACTIVITY WILL ALSO START TO WEAKEN AS THIS OCCURS. WILL INCLUDE A VCTS FOR BOTH SITES FOR A COUPLE OF HOURS AS THE BEST COVERAGE IS OVER CENTRAL WISCONSIN. FOCUS THEN TURNS TO THE INCOMING COLD FRONT FOR THE AFTERNOON. THE 19.06Z NAM INDICATES THE MAIN UPPER LEVEL TROUGH WILL STILL BE BACK ACROSS THE DAKOTAS LATE THIS AFTERNOON BUT THAT THERE WILL BE A LEAD SHORT WAVE TROUGH AHEAD OF THIS. THIS SHORT WAVE TROUGH WILL BE COMING WITH THE COLD FRONT AND SHOULD HELP WIDESPREAD SHOWER AND STORMS DEVELOP DURING THE AFTERNOON. THE 19.08Z ARX LAPS AND 19.07Z HRRR SUGGEST THE CONVECTION WILL START TO IMPACT BOTH SITES BETWEEN 21Z AND 22Z AND SHOULD LAST FOR A COUPLE OF HOURS UNTIL THE FRONT COMES THROUGH SWINGING THE WINDS AROUND TO THE NORTHWEST. THE FORCING FROM THE MAIN SHORT WAVE TROUGH WILL BE BEST RIGHT BEHIND THE FRONT SO EXPECTING A 2 TO 3 HOUR PERIOD OF SOME POST- FRONTAL SHOWERS TO OCCUR WITH MVFR CEILINGS. ONCE THIS ACTIVITY ENDS...DRIER AIR STARTS TO WORK IN TO ALLOW THE CEILINGS TO GO UP TO VFR FOR THE REMAINDER OF THE PERIOD. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...04
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
320 PM MDT THU SEP 19 2013 .SHORT TERM...AREA OF ELONGATED MID LEVEL POTENTIAL VORTICITY EXTENDING FROM FAR NORTHEAST COLORADO SOUTHWEST ACROSS THE PLAINS INTO THE SOUTHERN FOOTHILLS AND PARK COUNTY HEADING EAST. THIS FEATURE HELPED DEVELOP ISOLATED RAIN SHOWERS...WITH A FEW THUNDERSTORMS OVER SOUTH PARK AND SOUTHERN FOOTHILLS. RAINFALL HAD BEEN LIGHT...LESS THAN A TENTH OF AN INCH. THIS ACTIVITY WAS SHIFTING EAST WITH THE POTENTIAL VORTICITY. LATEST SATELLITE SHOWING A DECENT BACK EDGE OF THE MOISTURE WITH DRIER AIR MOVING SOUTH. MODELS SHOW THIS FEATURE CONTINUING TO SHIFT EAST INTO THE EVENING...WITH THE LATEST HRRR AND RAP SHOWING ALL THE PRECIPITATION EAST OF THE AREA BY MIDNIGHT. THIS SEEMS REASONABLE BASED ON THE CURRENT TRENDS. WILL KEEP A SLIGHT CHANCE OF STORMS ACROSS PARK COUNTY AND SOUTHERN FOOTHILLS AND PALMER DIVIDE THIS EVENING. THE NAM SEEMS A BIT SLOWER IN SHIFTING THE PRECIPITATION EASTWARD...WILL LEAN TOWARD THE HRRR AND RAP SOLUTIONS. AFTER MIDNIGHT...LOW LEVEL SOUTHEAST WINDS COULD BRING SOME LOW LEVEL MOISTURE BACK INTO THE FOOTHILLS. THIS SHOWN BY FORECAST SOUNDINGS. WILL INCREASE CLOUD COVER A BIT...ESPECIALLY ACROSS LINCOLN COUNTY. OVERNIGHT TEMPERATURES TO COOL INTO THE 40S ACROSS NORTHEAST COLORADO WITH MOUNTAIN VALLEYS NEAR OR BELOW FREEZING. ON FRIDAY...UPPER RIDGE OVER GREAT BASIN SHIFTS EAST WITH THE AXIS ALONG THE COLORADO WESTERN BORDER. NORTHWEST FLOW ALOFT WILL CONTINUE TO SPREAD DRIER AND MORE SUBSIDENT AIR ACROSS THE THE AREA. CLOUDS SHOULD DECREASE DURING THE MORNING WITH MAINLY SUNNY CONDITIONS BY THE AFTERNOON. TEMPERATURES ACROSS THE PLAINS TO WARM INTO THE LOWER AND MIDDLE 70S. .LONG TERM...A PAIR OF WEATHER SYSTEMS WILL MOVE ACROSS THE STATE...ONE ON SUNDAY AND ANOTHER LATE NEXT WEEK. IN THE MEANTIME...DRY AND SEASONABLE TEMPERATURES WILL PREVAIL. THE GFS AND ECMWF MODELS ARE IN GOOD AGREEMENT AS THESE WELL DEFINED TROUGHS TRAVERSE ACROSS THE WESTERN UNITED STATES. SATURDAY WILL BE WARM AND SUNNY WHILE SUNDAY WILL BE A TRANSITION AHEAD OF THE APPROACHING SYSTEM. PRECIPITATION SHOULD SPREAD INTO THE MOUNTAINS BY SUNDAY AFTERNOON AND THEN MOVE ACROSS THE PLAINS SUNDAY NIGHT. TEMPERATURES COULD DROP COLD ENOUGH FOR A CHANCE OF SNOW ABOVE 11000 FEET AS THE SYSTEM MOVES THROUGH. BEYOND SUNDAY...A RETURN TO WESTERLY FLOW ALOFT WILL BRING WARM TEMPERATURES AND DRY WEATHER BACK TO THE FORECAST AREA. NEXT FRIDAY MAY BE THE NEXT TIME THE FORECAST AREA SEES ANY PRECIPITATION. AT THIS TIME...THE SYSTEM LOOKS A BIT STRONGER THAN THE FIRST SYSTEM OVER THIS WEEKEND. && .AVIATION...NORTHEAST TO EAST WINDS TO SHIFT TO THE SOUTHEAST BY 00Z AS SURFACE HIGH MOVE SOUTH ACROSS THE EASTERN PLAINS. MODELS CONTINUE TO SHOW SOME LOW LEVEL MOISTURE SPREADING NORTH AFTER 06Z. CEILINGS OF 4000 TO 6000 FEET AGL STILL EXPECTED TO DEVELOP BETWEEN 07Z AND 13Z. SOUTHEAST SURFACE WINDS TO CONTINUE THROUGH THE DAY FRIDAY AS DRIER AIR SPREADS OVER THE AREA. SHOULD SEE CEILINGS IMPROVE AFTER 13Z. && .HYDROLOGY...LINGERING SHOWERS AND A FEW THUNDERSTORMS ACROSS SOUTH PARK AND SOUTHERN FOOTHILLS WILL COME TO AN END AROUND MIDNIGHT AS DRIER AIR MOVES INTO THE REGION. ANY RAINFALL AMOUNTS WILL BE LIGHT. NO SHOWERS OR STORMS EXPECTED FRIDAY. RIVER LEVELS HAVE FLATTENED AND WILL GRADUALLY RECEDE OVER THE NEXT FEW DAYS. && .BOU WATCHES/WARNINGS/ADVISORIES... FLOOD WARNING CONTINUES FOR THE SOUTH PLATTE RIVER FROM KERSEY TO THE NEBRASKA STATE LINE. && $$ SHORT TERM...D-L LONG TERM....DANKERS AVIATION...D-L
AREA FORECAST DISCUSSION
NWS PUEBLO CO
338 PM MDT THU SEP 19 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 317 PM MDT THU SEP 19 2013 FAIRLY MEAGER CONVECTION OUT THERE SO FAR WITH DEW POINTS STRUGGLING TO REBOUND ALONG THE NORTHERN PORTIONS OF THE AREA BEHIND THIS MORNING`S COLD FRONT. THEY ARE SLOWLY CREEPING UP INTO THE LOWER 40S TO MID 40S ACROSS EL PASO AND PUEBLO COUNTIES AS WINDS SWING AROUND FROM THE EAST THIS AFTERNOON. FARTHER EAST...DEW POINTS AT KLHX AND KLAA ARE STILL HOVERING IN THE 50S. THUS HIGHEST MIXED LAYER CAPES OFF OF SPC MESO ANALYSIS IS RUNNING AROUND 1000 J/KG ACROSS THE SOUTHEAST PLAINS SOUTH OF HIGHWAY 50...BUT THERE APPEARS TO BE A LITTLE CIN TO OVERCOME YET OUT THAT WAY. AS THE UPPER TROF TRAILS ACROSS THE AREA THIS EVENING...SHORT RANGE HIGH RES MODELS (LOCAL 4KM WRF...HRRR AND NAM12) ALL SHOW A WINDOW FOR SOME ISOLATED SHOWERS AND THUNDERSTORMS ACROSS THE SOUTHEAST MTS/SPREADING INTO THE ADJACENT PLAINS THROUGH THE EVENING. WITH FORCING STILL COMING THROUGH ITS HARD TO ARGUE. HOWEVER...HAVE NOTICED TREND IN HRRR TO DECREASE COVERAGE OF QPF ACROSS THE SOUTHERN I-25 CORRIDOR WITH EACH RUN. AFTER MIDNIGHT THINK MOST OF THE ACTIVITY WILL BE DONE...HOWEVER...LOW LEVEL WINDS SWING AROUND FROM THE SOUTHEAST AND MODEL SOUNDINGS BECOME DEEPLY SATURATED SUGGESTING POTENTIAL FOR LOTS OF LOW CLOUDS...FOG...AND EVEN PATCHY DRIZZLE ALONG THE SOUTHERN SLOPES OF THE PALMER DIVIDE WHERE UPSLOPE WILL BE MAXIMIZED. HAVE THROWN IN SOME ISOLATED -SHRA AND DRIZZLE FOR THE LATE NIGHT/EARLY MORNING HOURS ALONG WITH AREAS OF FOG ALONG THE I-25 CORRIDOR. STRATUS WILL SLOWLY CLEAR ON FRIDAY...THOUGH THINK THAT SOUTHERN SLOPES OF THE PALMER DIVIDE/COLORADO SPRINGS AREA MAY HANG ON TO CLOUD COVER THROUGH THE MORNING BEFORE BREAKS START TO APPEAR IN THE AFTERNOON...AS IS THE TYPICAL PATTERN FOR SOUTHERLY UPSLOPE CASES. OTHERWISE...MODELS KEEP FORECAST AREA DRY FRIDAY AFTERNOON...WITH SE PLAINS REMAINING CAPPED. TEMPERATURES SHOULD BE ABOUT A CATEGORY COOLER THAN THOSE OF TODAY. -KT .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 317 PM MDT THU SEP 19 2013 GENERALLY WARM AND DRY WEATHER STILL ON TRACK FOR THE EXTENDED...WITH JUST A COUPLE OF STORM SYSTEMS TO CONTEND WITH. THE WEEKEND STARTS OUT WARM AND DRY. SHOULD SEE 80S OVER THE PLAINS BOTH SAT AND SUNDAY. GFS MOS CONTINUES TO LOOK TOO WARM FOR THE PLAINS...SO HAVE STAYED ON THE COOL SIDE OF GUIDANCE...PARTICULARLY SUNDAY AS HIGH CLOUDS START MOVING IN FROM THE WEST. SOME MODEL DISCREPANCIES FOR OUR FIRST SHORT WAVE LATE SUNDAY. THE TREND HAS BEEN TOWARDS A SLIGHTLY DEEPER OR SHARPER TROUGH...WHICH THE ECMWF HAS BEEN ADVERTISING FOR A WHILE NOW. THE GFS NOW LOOKS COOLER AND WETTER...AND WOULD BRING SEVERAL INCHES OF SNOW TO THE AREA ABOVE 9K FEET SUNDAY NIGHT. THE NAM IS CONSIDERABLY WARMER AND PROBABLY WOULD JUST LEAD TO TRACE SNOW AMOUNTS. THE TRUTH LIKELY IS SOMEWHERE IN BETWEEN...BUT PROBABLY CLOSER TO THE GFS. SHOULD KNOW BETTER BY TOMORROW OR FRIDAY IF THE NAM MOVES TOWARD A COOLER SOLUTION. HAVE BUMPED UP POPS ABOUT 10-20 PERCENT AREA WIDE AS THE TROUGH MOVES THROUGH SUN NIGHT. MONDAY AND TUESDAY...THINGS REALLY DRY OUT IN ZONAL FLOW...AND WE SHOULD SEE SOME REAL PLEASANT FALL WEATHER WITH LOTS OF SUNSHINE AND TEMPS IN THE 70S-NR 80 FOR THE LOWLANDS AND 60S FOR THE HIGHER VALLEYS. POPS ESSENTIALLY NIL EVEN FOR THE MTS. NEXT SYSTEM BEGINS TO TAKE SHAPE ON WED THROUGH THU AS A DEEPER TROUGH MOVES THROUGH THE PACNW AND INTO THE INTER-MOUNTAIN REGION. STILL PLENTY OF UNCERTAINTY WITH THE TIMING AND DEPTH OF THIS LOW...BUT THE TREND FOR A WHILE NOW HAS BEEN FOR IT TO LIFT INTO THE NRN ROCKIES BY LATE THU OR FRI...WHICH WOULD BRING MOST OF THE PRECIP N OF OUR CWA AND LEAVE US IN A DRY AND BREEZY CORNER. CERTAINLY DOES NOT LOOK LIKE A BIG STORM FOR OUR AREA...BUT THE MTS SHOULD SEE AT LEAST SOME LIGHT SNOWFALL ABOVE 9 OR 10K FEET AS H7 TEMPS DROP CLOSE TO ZERO BY THE END OF THE WEEK. ROSE && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING) ISSUED AT 317 PM MDT THU SEP 19 2013 ISOLATED SHOWERS AND THUNDERSTORMS WILL DEVELOP ACROSS THE MOUNTAINS AND SPREAD OFF INTO THE ADJACENT PLAINS DURING THE AFTERNOON AND EARLY EVENING. THE MAIN THREAT WITH THUNDERSTORMS WILL BE SOME BRIEF MODERATE RAINFALL AND WIND GUSTS TO AROUND 40 KTS...AS WELL AS LIGHTNING. OVERNIGHT...WINDS ACROSS THE PLAINS WILL SHIFT AROUND FROM THE SOUTHEAST WITH WIDESPREAD STRATUS AND AREAS OF FOG AND PATCHY DRIZZLE DEVELOPING ALONG THE LOWER EASTERN SLOPES OF THE SOUTHEAST MTS AND I-25 CORRIDOR AFTER 06Z. EXPECT IFR TO LIFR CIGS/VIS FOR KCOS AND KPUB TO DEVELOP AFTER 06Z WITH THE LOWEST CIGS/VIS ACROSS SOUTHERN EL PASO COUNTY INCLUDING KCOS. CIGS WILL BE SLOW TO BREAK ACROSS THE SE PLAINS ON FRIDAY...PARTICULARLY FOR KCOS DUE TO PERSISTENT SOUTHERLY FLOW. CIGS MAY LIFT INTO THE MVFR TO IFR CATEGORY AROUND 18Z...BEFORE CLEARING AFTER THAT. KALS WILL REMAIN UNDER VFR CONDITIONS THROUGH THE NIGHT. THERE IS A LOW PROBABILITY FOR A REPEAT THREAT FOR FOG OVERNIGHT AT KALS...BUT CHANCES LOOK TOO LOW TO WARRANT MENTION IN TAFS AT THIS POINT. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...KT LONG TERM...ROSE AVIATION...KT
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1034 AM MDT THU SEP 19 2013 .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 310 AM MDT THU SEP 19 2013 COLD FRONT IS NOW LOCATED ALONG I-70 AND IS EXPECTED TO CONTINUE DROPPING SEWRD TO NEAR THE SAN JUAN MOUNTAINS BEFORE WASHING OUT. THE UPPER LEVEL TROUGH IS LAGGING BEHIND THE SFC FRONT AND IS JUST ENTERING WRN CO AT THIS HOUR. AHEAD OF THE TROUGH...RADAR PICKING UP SOME RETURNS N OF I-70 WITH A FEW STRAY STORMS ALSO FORMING THANKS TO UPPER LEVEL SUPPORT AND OROGRAPHIC LIFT. EXPECT THIS TO CONTINUE THROUGH DAYBREAK WITH SOME MIDLEVEL CLOUDS AROUND THE AREA FOR THE COMMUTE TO WORK. 00Z NAM12 SHOWED SOME VERY ISOLD SHOWERS OVER CENT/SRN MTNS THIS AFTERNOON DUE TO LIMITED MOISTURE AND SOME OROGRAPHICS WHILE 06Z NAM12 HAS ALL BUT REMOVED THEM. LATEST HRRR AND RAP13 GUIDANCE ALSO SHOWING A DISTINCT LACK OF PRECIP FOR THE ENTIRE CWA TODAY. NOT SOLD ON IDEA THOUGH AS SOME MARGINAL INSTABILITY EXISTS ALONG WITH SOME MOISTURE IN LOWER LEVELS. FOR NOW...WILL LEAVE ISOLD CONVECTION IN FORECAST FOR THE HIGHEST TERRAIN IN THE SAN JUANS AND CENTRAL MTNS. MOST AREAS TODAY WILL SEE SUN...SUN...AND MORE SUN AND MORE FALL LIKE TEMPERATURES AS A PATTERN SHIFT FINALLY SETS UP. ANY LINGERING SHOWER OR STORM NEAR THE CENTRAL OR SOUTHERN DIVIDE WILL QUICKLY DIMINISH THIS EVENING WITH SUNSET. WEAK WARM ADVECTION ALOFT THEN COMMENCES TONIGHT AS A PROGRESSIVE UPPER RIDGE APPROACHES...BUT IT WILL NOT LIKELY BE ENOUGH TO OFFSET RADIATIONAL COOLING DUE TO CLEAR SKIES AND DRIER AIR. HENCE...A COOL NIGHT LOOKS IN STORE WITH POCKETS OF FREEZING OR NEAR FREEZING TEMPS TO THE LOWER VALLEYS IN THE CRAIG AND MEEKER AREAS AND WILL CONTINUE THE FREEZE WATCH FOR THESE AREAS TONIGHT. MODELS SUGGEST THAT THE STEAMBOAT VALLEY AND AROUND GUNNISON WILL BOTTOM OUT IN THE MID 30S. TEMPS SHOULD WARM QUICKLY FRIDAY MORNING WITH PLENTY OF SUNSHINE. DRY AND SUNNY CONDITIONS ARE EXPECTED FRIDAY WITH HIGH TEMPS REBOUNDING AS THE UPPER RIDGE SLIDES ACROSS THE AREA. AFTERNOON HUMIDITIES WILL DROP INTO THE TEENS FRIDAY AFTERNOON IN MANY OF THE NORTHWEST AND WEST-CENTRAL COLORADO VALLEYS...AND EASTERN UTAH VALLEYS. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 310 AM MDT THU SEP 19 2013 FLOW ALOFT BECOMES SOUTHWEST FRIDAY NIGHT AND SATURDAY AS THE UPPER RIDGE MOVES TO THE EAST AND A PACIFIC TROUGH PUSHES INLAND. GRADIENT TIGHTENS SATURDAY AS THE TROUGH ADVANCES FOR STRENGTHENING AND GUSTY SURFACE WINDS ACROSS NE UT/NW CO SATURDAY AFTERNOON...AND TEMPS SHOULD WARM OVER FRIDAY. NAM MODEL SHOWS MID-LEVEL MOISTURE BEING DRAWN NORTHWARD INTO SW CO AS EARLY AS FRI NIGHT WHILE THE GFS WAITS UNTIL SAT. THE EVENING MODELS ALSO DID SEEM QUITE AS ENTHUSIASTIC WITH RAISING PRECIPITABLE WATER VALUES AS EARLIER RUNS. STILL...MAY SEE A FEW SHOWERS OR THUNDERSTORMS OVER THE SAN JUANS SAT AFTERNOON AND MADE LITTLE CHANGE TO THE CURRENT FORECAST FOR THE FIRST HALF OF THE WEEKEND. BIG DIFFERENCE IN LONG-TERM FOR THE WEEKEND AS PREVIOUS GFS RUNS SHOWED MARGINAL PRECIP WITH AN APPROACHING TROUGH AND SFC COLD FRONT WHILE LATEST RUN SHOWS SIGNIFICANT PRECIP FOR MUCH OF THE AREA SUNDAY AFTERNOON AND NIGHT. EC ALSO SHOWING THIS PRECIP WHILE NAM12 SHOWING VERY LITTLE AT THIS TIME. MOISTURE TRANSPORT VECTORS ON THE 320K SURFACE DO SHOW SOME MOISTURE STREAMING UP FROM THE SOUTH SATURDAY NIGHT INTO SUNDAY MORNING BEFORE BEING WORKED ON BY THE TROUGH. THE TROUGH WILL BE SUPPORTED BY AN 80 KT JET STREAK AND IT LOOKS LIKE THIS TROUGH MAY BECOME NEGATIVELY TILTED. IF YOU PUT ALL OF THESE TOGETHER...SOME WIDESPREAD PRECIP CAN BE EXPECTED WITH SOME STRONG THUNDERSTORMS POSSIBLE. CAN ALSO EXPECT SOME GUSTY SFC WINDS...ESPECIALLY SUNDAY...AHEAD OF SAID FRONT. SOME WHITE STUFF ALSO POSSIBLE AT THE HIGHEST ELEVATIONS...ABOVE 13K FT...AS H7 TEMPS DROP TO AROUND 3C. SFC TEMPERATURES WILL DROP 8 TO 10 DEGREES FROM SATURDAY TO SUNDAY AS THE COLD FRONT PUSHES THROUGH. BY MONDAY MORNING...THE TROUGH AND FRONT WILL HAVE EXITED OUR AREA ALLOWING ZONAL FLOW TO SET UP BRINGING A PERIOD OF DRY WEATHER AND SEASONAL TEMPERATURES THROUGH WEDNESDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1034 AM MDT THU SEP 19 2013 VFR CONDITIONS WILL CONTINUE OVER THE REGION THROUGH THE NEXT 24 HOURS AS DRIER AIR BRINGS QUIET WEATHER TO REGION. A FEW THUNDERSTORMS REMAIN A POSSIBILITY OVER THE RIDGES ALONG THE CONTINENTAL DIVIDE FROM 19Z THROUGH 01Z FRIDAY. THIS ACTIVITY WILL RESULT IN BRIEF AND LOCALIZED RIDGE AND PEAK OBSCURATIONS AND SHOULD NOT AFFECT AIRPORT FLIGHT OPERATIONS. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...FREEZE WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING FOR COZ002. UT...NONE. && $$ SHORT TERM...TGR/JAD LONG TERM...JAD/TGR AVIATION...NL
AREA FORECAST DISCUSSION
NWS MIAMI FL
227 PM EDT THU SEP 19 2013 .SHORT TERM (TONIGHT-SATURDAY NIGHT)... THIS EVENING...THE LATEST RADAR SCAN SHOWED SCATTERED ACTIVITY DEVELOPING OVER THE INTERIOR AREAS SPREADING WESTWARD TOWARD THE GULF COAST. THE LATEST HRRR MODEL RUNS LINE UP WELL WITH THIS AND INDICATE THIS ACTIVITY BECOMING FOCUSED OVER AND AROUND THE GULF COAST AREAS THROUGH THE LATE AFTERNOON AND EVENING HOURS ONCE AGAIN. CONSIDERING THE EXTENSIVE RAINFALL COVERAGE OVER THE GULF COAST YESTERDAY...THE MAIN CONCERN THROUGH THIS EVENING WILL BE THE POTENTIAL FOR ADDITIONAL HEAVY RAINFALL AND FLOODING DUE TO THE SATURATED GROUNDS. FRIDAY THROUGH SATURDAY NIGHT...THE LATEST NUMERICAL GUIDANCE REMAINS IN DECENT AGREEMENT THROUGH THIS PERIOD AND SHOWS WHAT IS LEFT OF THE WEAKENING BOUNDARY OR TROUGH CURRENTLY MOVING INTO THE AREA CONTINUING SOUTH WITH SOME DRIER AIR FILLING IN BEHIND IT FROM THE NORTH. THIS COMBINED WITH THE MEAN LOW-LEVEL FLOW UP TO 10 KFT SHIFTING TO THE NORTH WILL TRANSLATE TO LOWER RAINFALL CHANCES EACH DAY. DEWPOINTS COULD REACH THE LOWER 60S ACROSS PORTIONS OF THE INTERIOR AREAS SATURDAY AFTERNOON. MODEL SOUNDINGS INDICATE PRECIPITABLE WATER VALUES DIPPING DOWN TO AROUND 1.3" ACROSS PORTIONS OF THE AREA BY SATURDAY. TEMPERATURES ARE FORECAST TO REMAIN AROUND NORMAL THROUGH THIS PERIOD...WITH THE EXCEPTION BEING THE POSSIBILITY OF REACHING THE UPPER 60S ACROSS THE NORTHERN INTERIOR AREAS BY DAYBREAK SATURDAY MORNING. .LONG TERM (SUNDAY-WEDNESDAY)... AN UPPER TROUGH IS FORECAST TO DIG ACROSS THE SOUTHEAST AND EASTERN SEABOARD THROUGH THE SECOND HALF OF THE WEEKEND. OUT AHEAD OF THIS...SURFACE AND LOW LEVEL FLOW WILL SHIFT TO THE SOUTH...BRINGING A SURGE OF MOISTURE BACK INTO SOUTH FLORIDA ON SUNDAY. MODELS HAVE BEEN TRENDING TOWARDS A WEAKER LOW LEVEL/SURFACE REFLECTION ACROSS THE SOUTHEAST...AND THUS A WEAKER COLD FRONT MOVING INTO THE SOUTHEAST STATES. THE ECMWF IS NOW STRONGER THAN THE GFS WITH THE BAROCLINIC SURFACE LOW ACROSS THE NORTHERN GULF COAST/SOUTHEAST STATES...AND DRAWS THE MOISTURE FROM THE BAY OF CAMPECHE SYSTEM TO THE NORTHEAST. REGARDLESS...SINCE THE MODELS HAVE TRENDED SLOWER WITH THE COLD FRONT AND KEEP IT ACROSS NORTH FLORIDA THROUGH EARLY NEXT WEEK...THE FOCUS FOR STORMS MAY BE ACROSS THE GULF WATERS AND NORTH OR CENTRAL FLORIDA. WITH NO FOCUS FOR RAINFALL ACROSS SOUTH FLORIDA AND EXTENSIVE CLOUD COVER POSSIBLY LIMITING RAINFALL AMOUNTS DURING THE DAY MONDAY AND TUESDAY...THE HEAVIEST RAINS MAY ACTUALLY FALL OVER THE NIGHT TIME HOURS AS SPEED/COASTAL CONVERGENCE SETS UP. THE GFS AND ECMWF ARE HINTING AT THIS AS WELL. SO RAINFALL CHANCES WILL LIKELY REMAIN HIGH SUNDAY THROUGH TUESDAY. THE FORECAST IS UNCLEAR BEYOND THAT POINT...BUT RAINFALL CHANCES WILL REMAIN ELEVATED THROUGH AT LEAST WEDNESDAY. && .AVIATION... SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP THROUGH THE AFTERNOON ACROSS THE INTERIOR AND MOVE TOWARDS KAPF WITH A FEW SHOWERS ALONG THE EAST COAST. SEA BREEZES ALONG BOTH COASTS UNTIL EARLY THIS EVENING. MOST CONVECTION SHOULD DIMINISH BY 00Z WITH DRIER AIR MOVING INTO THE AREA THROUGH EARLY FRIDAY. && .MARINE... LIGHT TO MODERATE NORTHEAST WINDS WILL CONTINUE THROUGH SATURDAY AS A WEAKENING FRONTAL BOUNDARY SHIFTS SOUTH INTO THE AREA. WINDS WILL SHIFT TO THE SOUTH THROUGH THE SECOND HALF OF THE WEEKEND AND INTO EARLY NEXT WEEK AS ANOTHER FRONTAL BOUNDARY APPROACHES FROM THE NORTH. SEAS OVER THE ATLANTIC WATERS SHOULD BEGIN TO SUBSIDE OVER THE WEEKEND. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 75 88 74 88 / 20 20 10 10 FORT LAUDERDALE 76 88 77 89 / 20 20 10 10 MIAMI 76 89 75 89 / 20 20 10 10 NAPLES 73 90 73 90 / 30 20 10 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...85/AG AVIATION/RADAR...30/KOB
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
109 PM CDT THU SEP 19 2013 .DISCUSSION... 338 AM CDT THE FORECAST CHALLENGES ARE CENTERED ON THE NEXT 36 HOURS AS AN UNSEASONABLY WARM AND MOIST AIR MASS FOR LATTER SEPTEMBER IN PLACE WILL KEEP THE POTENTIAL FOR STORMS THROUGH TODAY AND AID IN ACTIVITY ALONG A COLD FRONT MOVING THROUGH LATER TONIGHT AND FRIDAY. THIS MORNING...PESKY MCV IS CENTERED OVER NORTHERN IN THIS MORNING AFTER ITS 18-24 HOUR EASTWARD TRACK OF TROUBLE FROM CENTRAL IA YESTERDAY MORNING. THE STORM ACTIVITY OF YESTERDAY AND LAST NIGHT KEPT THE LOW-LEVEL WARM FRONT FROM DEVELOPING TOO QUICKLY NORTHWARD...SO THAT IS ROUGHLY ANALYZED FROM A 1001MB LOW ACROSS EASTERN SD THROUGH SOUTHERN MN AND INTO THE WESTERN AND SOUTHERN FORECAST AREA. WARM AIR ADVECTION INDUCED ASCENT NORTH OF THIS HAS ONCE AGAIN SPARKED CONVECTION IN THE FAST PACED WSW MID- LEVEL FLOW EARLY THIS MORNING...THIS TIME ACROSS SW WI/NE IA/NW IL. A SUBTLE SHORT WAVE IS NOTED IN WATER VAPOR AND ANALYZED BY HIGH RES MODELS AS WELL. AS THE LOW-LEVEL JET AND ASSOCIATED MOISTURE TRANSPORT VEER EASTWARD THIS MORNING...SOME OF THIS ACTIVITY SHOULD FEED ON INSTABILITY AND TRAVERSE THE FORECAST AREA AHEAD OF THE WAVE. AMDAR SOUNDING FROM ROCKFORD EARLY THIS MORNING SHOWED 1300 J/KG OF ELEVATED CAPE WHEN LIFTING FROM 850MB...SO SOME FUEL THERE FOR STORMS AND POSSIBLY A COUPLE STRONGER ONES CAPABLE OF SMALL HAIL...GUSTY WINDS...AND VERY EFFICIENT RAINFALL. EXPECT THE ACTIVITY TO MOVE MAINLY EAST OF THE FORECAST AREA BY LATE MORNING/EARLY AFTERNOON WITH WARM AIR ADVECTION CLOUDS SCATTERING. THIS AFTERNOON...THE THERMAL RIDGE AHEAD OF THE SYSTEM COLD FRONT DEVELOPS NORTHEAST OVER THE AREA THIS PERIOD AND IS ROBUST FOR THIS TIME OF YEAR...WITH 850MB TEMPERATURES OF 18C-20C FROM EAST TO WEST ACROSS THE CWA. LOCAL CLIMATOLOGY SUPPORTS HIGHS AROUND 90...OR IN OTHER WORDS WITHIN 5F OF RECORD HIGHS FOR TODAY. SOME OF THE MORNING CLOUDS...ESPECIALLY ACROSS THE NORTHEAST FORECAST AREA WHERE THEY MAY LAST THE LONGEST...WILL HINDER THAT SOME. OTHERWISE GOING FORECAST HIGHS CONTINUE TO LOOK GOOD AND ARE SUPPORTED BY SOME OF THE BEST VERIFYING GUIDANCE ON WARM DAYS WITHIN THIS PAST MONTH. IF STORMS FESTER FOR LONGER THIS MORNING AND CONTINUE INTO AFTERNOON...THEN GOING FORECAST IS TOO HIGH BY SEVERAL DEGREES. WHILE MLCAPES ARE FORECAST TO BUILD TO 2000-2500 J/KG ACROSS THE CWA LIKELY ERODING CIN BY MID TO LATE AFTERNOON...THE FOCUS OF PRE-FRONTAL CONVERGENCE AND SHORT WAVE ENERGY STILL MAINLY LOOKS TO BE AFTER 00Z. BUT THIS IS A HIGH PWAT WARM SECTOR WITH LIMITED CAPPING AND AS YESTERDAY SHOWED...EVEN SOMETHING SUBTLE CAN CAUSE PROBLEMS. SO START INCHING UP POPS IN THE WESTERN CWA LATE THIS AFTERNOON. IF STORMS CAN MAKE IT IN THAT EARLY...SCATTERED SEVERE POTENTIAL IS THERE GIVEN JUST THE INSTABILITY AND PWATS. TONIGHT AND FRIDAY...THE SURFACE LOW WILL DEVELOP NORTHEASTWARD INTO ONTARIO TONIGHT STEERING THE COLD FRONT INTO THE WESTERN FORECAST AREA LIKELY BY AROUND DAYBREAK FRIDAY. FOCUS FOR CONVECTION REMAINS GOOD...ESPECIALLY FOR THE WESTERN FORECAST AREA THIS EVE INTO EARLY OVERNIGHT. A SCATTERED SEVERE THREAT EXISTS EVEN WITH MARGINAL DEEP LAYER SHEAR. MUCH LIKE YESTERDAY...THE THREATS FROM LIKELY MULTI-CELL OR SOMEWHAT LINEAR ACTIVITY THAT COULD REACH SEVERE LIMITS WOULD BE VERY HEAVY RAINFALL...GUSTY WINDS...AND HAIL. SOME INDICATION IN BOTH THE 19.00 NAM AND GFS THAT THE BEST DEEP CONVERGENCE SORT OF SPLITS THE EASTERN FORECAST AREA AS THE BOUNDARY ADVANCES...AND SEVERAL CONVECTIVE ALLOWING GUIDANCE MEMBERS DO SHOW A GENERAL DECREASE IN REFLECTIVITY INTO THE OVERNIGHT. THINK THAT MAY BE A LITTLE TOO EAGER TO DIMINISH CONVECTION GIVEN THE PWATS AT TWO STANDARD DEVIATIONS ABOVE NORMAL AND A WELL-DEFINED COLD FRONT MOVING INTO THAT AIR MASS. SO STILL HAVE MAINTAINED HIGH POPS EVEN FURTHER EAST LATE INTO THE NIGHT AND INTO FRIDAY MORNING. DID ADD MENTION OF HEAVY RAIN IN THE WESTERN FORECAST AREA GIVEN THE HIGH LIKELIHOOD OF RAIN IN A MOIST AND REPLENISHING AIR MASS. THANKFULLY THAT AREA DID NOT RECEIVE THE HIGHER RAIN YESTERDAY. A REGENERATION OF STRONGER CONVECTION ON FRIDAY LOOKS POSSIBLE...BUT MAINLY EAST OF THE FORECAST AREA ON THE MEAN OF MODEL GUIDANCE. COULD SEE A LITTLE SLOW DOWN AGAIN...BUT AT THIS POINT NOT TOO CONCERNED ON A SEVERE THREAT FRIDAY IN OUR CWA. MORE SO IT WOULD STILL BE THE HEAVY RAIN POTENTIAL. MILD TEMPERATURES TONIGHT LOOK TO CLIMB TO THE MID 70S TO 80 ON FRIDAY AS THE COLD AIR ADVECTION ENSUES ALOFT. SATURDAY AND BEYOND...GIVEN ACTIVE SHORT TERM WEATHER HAVE GONE WITH A SMART CONSENSUS BLEND DURING THIS TIME. WITH 850MB TEMPERATURES FORECAST BY THE NAM/GFS/EC OF 3C-5C OVER LAKE MI...SOME LAKE EFFECT CLOUDS ARE LIKELY SATURDAY NIGHT INTO EARLY SUNDAY INTO NW IN/NE IL AS THE WINDS VEER NNE OVER THE LAKE. OVER LAND SATURDAY NIGHT CONDITIONS SHOULD BE CLOSER TO CALM. SO THAT SPELLS WHAT COULD BE QUITE AN IMPRESSIVE TEMPERATURE CONTRAST ACROSS CHICAGOLAND AND HAVE THAT AT ALMOST 20F IN THE FORECAST SUNDAY MORNING...WITH LOWS AROUND 39F IN AURORA WHILE 58F DOWNTOWN CHICAGO. THE SURFACE HIGH MOVES EASTWARD EARLY NEXT WEEK WITH VERY GRADUALLY DEVELOPING WARM AIR ADVECTION. TEMPERATURES ARE FORECAST TO INCH UP A COUPLE DEGREES EACH DAY. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * MAIN CONCERN IS TIMING AND EXTENT OF ADDITIONAL CONVECTION TODAY...HOPING IT HOLDS OFF UNTIL AFTER EVENING RUSH. * IN THE SHORT TERM THE WINDS SHOULD BE TURNING SOUTHWEST AND INCREASING BUT EFFECTS OF EARLIER CONVECTION ARE STILL BEING FELT. * LINGERING MVFR VSBY EXPECTED TO IMPROVE SHORTLY. LENNING //DISCUSSION...UPDATED 18Z... CONVECTION THAT MOVED THROUGH THIS MORNING HAS EXITED THE TERMINALS TO THE EAST. SATELLITE PICS AND UPSTREAM OBS SUGGEST CONDITIONS SHOULD BE IMPROVING RAPIDLY EARLY THIS AFTERNOON BEFORE ADDITIONAL CONVECTION DEVELOPS WITH AN APPROACHING COLD FRONT THIS EVENING. THERE IS A CHANCE OF SEEING SOME TSRA DEVELOPMENT THIS AFTERNOON EARLIER THAN DEPICTED IN THE 18Z TAFS...BUT FCST MODELS MATCH LATEST RADAR TRENDS IN KEEPING THE BULK OF THE ACTIVITY ALONG OR BEHIND THE FRONT WHICH ARRIVES WELL AFTER MIDNIGHT. UNFORTUNATELY THINGS COULD START SLOW AGAIN TOMORROW MORNING BEFORE PRECIP COMES TO AN END WITH POSTFRONTAL WINDS VEERING NORTHWEST AND SKIES IMPROVING. LENNING //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM CONFIDENCE OF NOT SEEING ADDITIONAL TSRA BEFORE FRONTAL TSRA ARRIVES TONIGHT. * MEDIUM TO HIGH CONFIDENCE OF IMPROVING CONDITIONS AND SOUTHWEST WINDS THIS AFTERNOON. * MEDIUM CONFIDENCE ON TIMING AND EXTENT OF ACTIVITY TONIGHT. LENNING //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH WEDNESDAY...VFR. WX NIL. KREIN && .MARINE... 300 AM CDT AN AREA OF LOW PRESSURE CENTERED OVER THE EASTERN DAKOTAS WILL WEAKEN SLIGHTLY AND TRACK NORTHEAST TO WESTERN ONTARIO BY THIS EVENING. SOUTHERLY WINDS TO AROUND 25 KT WILL PERSIST OVER THE LAKE AS THE THE LOW DEEPEN FURTHER AND TRACKS NORTHEAST INTO NORTHERN QUEBEC BY SATURDAY MORNING. AN ASSOCIATED COLD FRONT WILL SWEEP ACROSS LAKE MICHIGAN FRIDAY AFTERNOON AND EVENING...WITH WINDS GRADUALLY VEERING FROM SOUTHWESTERLY TO NORTHWESTERLY AND...ULTIMATELY NORTHEASTERLY...AS A LARGE AREA OF HIGH PRESSURE BUILDS IN BEHIND THE FRONT. IN THE COLD ADVECTION BEHIND THE FRONT...NORTHWEST TO NORTH WINDS WILL REDEVELOP...WITH SOME OCCASIONAL GUSTS TO 30KT POSSIBLE FRIDAY NIGHT. KREIN && .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 1250 PM CDT Thu Sep 19 2013 .DISCUSSION... ISSUED 1040 AM CDT Thu Sep 19 2013 Warm front has lifted well to the northeast of central Illinois this morning, leaving behind partly to mostly sunny skies and very warm temps in the upper 70s and lower 80s. Convection continues to fire along the edge of the strengthening cap in the warm sector, mainly from southern Lake Michigan S/SE across Indiana into the Ohio River Valley. As warm air aloft spreads further east, this activity will continue to shift further away from Illinois this afternoon. End result will be a hot and mainly dry day, with perhaps a few isolated thunderstorms. Afternoon high temps will reach the upper 80s and lower 90s. Better thunderstorm chances will arrive by late evening across the Illinois River Valley. Latest HRRR shows a line of convection developing along an advancing cold front and pushing toward the Illinois River by around 03z. This activity should continue eastward in a weakening state overnight. Barnes && .AVIATION... ISSUED 1250 PM CDT Thu Sep 19 2013 Southwesterly winds gusting to around 20kt will prevail at the KILX terminals throughout the afternoon before subsiding to around 10kt by sunset. Will see a gradual increase in mid-level cloudiness, with BKN conditions expected by around 00z. Forecast soundings remain rather dry through the evening before an advancing cold front comes into the picture toward midnight. HRRR brings scattered showers/thunder into the Illinois River Valley after 04z...while NAM and 4km WRF-NMM are similar. All models tend to develop a vigorous line of convection with the front late this afternoon/early this evening well west of the Mississippi River, then weaken it considerably as it pushes into central Illinois overnight. For that reason, have decided to limit the convection in the 18z TAFs. Will carry a tempo group for thunder at only KPIA between 07z and 11z...with just predominant showers and VCTS further east at the remaining terminals late tonight into Friday morning. Winds will remain southwesterly overnight, then will veer to west-northwest after FROPA Friday morning. Barnes && .PREV DISCUSSION... ISSUED 251 AM CDT Thu Sep 19 2013 Developing storm system over the northern Plains to be the main issue for the forecast in the Midwest for this package. High pressure over the Atlantic seaboard slowly sliding eastward with southerly flow ramping up over the region in the middle of the country. Sunshine and WAA will send temperatures well above normal ahead of the storm system. All the warm air in place will provide instability for advancing chances of thunderstorms through tonight and tomorrow. Biggest issues for the forecast revolve around the timing of the front vs. max heating, and speed of the front itself. Ongoing convection already starting to hint that the mesoscale influences with prefrontal trofs and outflow boundaries will more than likely complicate the forecast of the details. Best chances for precip tonight and through tomorrow. SHORT TERM...Today and tomorrow... Hot today with the ridge expanding into the Midwest. Warmest midlevels in western CWA but will likely be countered somewhat by advancing clouds. However, front will hold off enough to see upper 80s over majority of the area. Cold front has slowed progression to tomorrow but convection ahead of the front and associated cold pools will mask some of the distinction of the leading edge. Plenty of instability in the region...but the cold front being delayed a bit results in the FA barely clipped by the slight risk outlook to the northwest for tonight. Frontal progression tomorrow to be slower, and already in rain and cloud cover from the overnight will likely inhibit intense storm development. So far tomorrow remains in a general thunder. Overnight Friday will see a clearing from west to east. Will need to keep an eye on guidance NW of Interstate 55 corridor for rapid clearing may result in a need for an adjustment of the lows down a couple degrees. LONG TERM...Saturday through Wednesday... Milder weather and dry through the extended. High pressure dominates the eastern half of the country and temperatures remain milder and closer to normal...with heat building again under a thermal ridge in the southwestern US. With southwesterly flow kicking in next week Tues, the extended could see some warmer temps as time draws nearer should the pattern persist. Guidance is still being pulled to 70s by climatology at this point. HJS && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1121 AM CDT THU SEP 19 2013 .DISCUSSION... 338 AM CDT THE FORECAST CHALLENGES ARE CENTERED ON THE NEXT 36 HOURS AS AN UNSEASONABLY WARM AND MOIST AIR MASS FOR LATTER SEPTEMBER IN PLACE WILL KEEP THE POTENTIAL FOR STORMS THROUGH TODAY AND AID IN ACTIVITY ALONG A COLD FRONT MOVING THROUGH LATER TONIGHT AND FRIDAY. THIS MORNING...PESKY MCV IS CENTERED OVER NORTHERN IN THIS MORNING AFTER ITS 18-24 HOUR EASTWARD TRACK OF TROUBLE FROM CENTRAL IA YESTERDAY MORNING. THE STORM ACTIVITY OF YESTERDAY AND LAST NIGHT KEPT THE LOW-LEVEL WARM FRONT FROM DEVELOPING TOO QUICKLY NORTHWARD...SO THAT IS ROUGHLY ANALYZED FROM A 1001MB LOW ACROSS EASTERN SD THROUGH SOUTHERN MN AND INTO THE WESTERN AND SOUTHERN FORECAST AREA. WARM AIR ADVECTION INDUCED ASCENT NORTH OF THIS HAS ONCE AGAIN SPARKED CONVECTION IN THE FAST PACED WSW MID- LEVEL FLOW EARLY THIS MORNING...THIS TIME ACROSS SW WI/NE IA/NW IL. A SUBTLE SHORT WAVE IS NOTED IN WATER VAPOR AND ANALYZED BY HIGH RES MODELS AS WELL. AS THE LOW-LEVEL JET AND ASSOCIATED MOISTURE TRANSPORT VEER EASTWARD THIS MORNING...SOME OF THIS ACTIVITY SHOULD FEED ON INSTABILITY AND TRAVERSE THE FORECAST AREA AHEAD OF THE WAVE. AMDAR SOUNDING FROM ROCKFORD EARLY THIS MORNING SHOWED 1300 J/KG OF ELEVATED CAPE WHEN LIFTING FROM 850MB...SO SOME FUEL THERE FOR STORMS AND POSSIBLY A COUPLE STRONGER ONES CAPABLE OF SMALL HAIL...GUSTY WINDS...AND VERY EFFICIENT RAINFALL. EXPECT THE ACTIVITY TO MOVE MAINLY EAST OF THE FORECAST AREA BY LATE MORNING/EARLY AFTERNOON WITH WARM AIR ADVECTION CLOUDS SCATTERING. THIS AFTERNOON...THE THERMAL RIDGE AHEAD OF THE SYSTEM COLD FRONT DEVELOPS NORTHEAST OVER THE AREA THIS PERIOD AND IS ROBUST FOR THIS TIME OF YEAR...WITH 850MB TEMPERATURES OF 18C-20C FROM EAST TO WEST ACROSS THE CWA. LOCAL CLIMATOLOGY SUPPORTS HIGHS AROUND 90...OR IN OTHER WORDS WITHIN 5F OF RECORD HIGHS FOR TODAY. SOME OF THE MORNING CLOUDS...ESPECIALLY ACROSS THE NORTHEAST FORECAST AREA WHERE THEY MAY LAST THE LONGEST...WILL HINDER THAT SOME. OTHERWISE GOING FORECAST HIGHS CONTINUE TO LOOK GOOD AND ARE SUPPORTED BY SOME OF THE BEST VERIFYING GUIDANCE ON WARM DAYS WITHIN THIS PAST MONTH. IF STORMS FESTER FOR LONGER THIS MORNING AND CONTINUE INTO AFTERNOON...THEN GOING FORECAST IS TOO HIGH BY SEVERAL DEGREES. WHILE MLCAPES ARE FORECAST TO BUILD TO 2000-2500 J/KG ACROSS THE CWA LIKELY ERODING CIN BY MID TO LATE AFTERNOON...THE FOCUS OF PRE-FRONTAL CONVERGENCE AND SHORT WAVE ENERGY STILL MAINLY LOOKS TO BE AFTER 00Z. BUT THIS IS A HIGH PWAT WARM SECTOR WITH LIMITED CAPPING AND AS YESTERDAY SHOWED...EVEN SOMETHING SUBTLE CAN CAUSE PROBLEMS. SO START INCHING UP POPS IN THE WESTERN CWA LATE THIS AFTERNOON. IF STORMS CAN MAKE IT IN THAT EARLY...SCATTERED SEVERE POTENTIAL IS THERE GIVEN JUST THE INSTABILITY AND PWATS. TONIGHT AND FRIDAY...THE SURFACE LOW WILL DEVELOP NORTHEASTWARD INTO ONTARIO TONIGHT STEERING THE COLD FRONT INTO THE WESTERN FORECAST AREA LIKELY BY AROUND DAYBREAK FRIDAY. FOCUS FOR CONVECTION REMAINS GOOD...ESPECIALLY FOR THE WESTERN FORECAST AREA THIS EVE INTO EARLY OVERNIGHT. A SCATTERED SEVERE THREAT EXISTS EVEN WITH MARGINAL DEEP LAYER SHEAR. MUCH LIKE YESTERDAY...THE THREATS FROM LIKELY MULTI-CELL OR SOMEWHAT LINEAR ACTIVITY THAT COULD REACH SEVERE LIMITS WOULD BE VERY HEAVY RAINFALL...GUSTY WINDS...AND HAIL. SOME INDICATION IN BOTH THE 19.00 NAM AND GFS THAT THE BEST DEEP CONVERGENCE SORT OF SPLITS THE EASTERN FORECAST AREA AS THE BOUNDARY ADVANCES...AND SEVERAL CONVECTIVE ALLOWING GUIDANCE MEMBERS DO SHOW A GENERAL DECREASE IN REFLECTIVITY INTO THE OVERNIGHT. THINK THAT MAY BE A LITTLE TOO EAGER TO DIMINISH CONVECTION GIVEN THE PWATS AT TWO STANDARD DEVIATIONS ABOVE NORMAL AND A WELL-DEFINED COLD FRONT MOVING INTO THAT AIR MASS. SO STILL HAVE MAINTAINED HIGH POPS EVEN FURTHER EAST LATE INTO THE NIGHT AND INTO FRIDAY MORNING. DID ADD MENTION OF HEAVY RAIN IN THE WESTERN FORECAST AREA GIVEN THE HIGH LIKELIHOOD OF RAIN IN A MOIST AND REPLENISHING AIR MASS. THANKFULLY THAT AREA DID NOT RECEIVE THE HIGHER RAIN YESTERDAY. A REGENERATION OF STRONGER CONVECTION ON FRIDAY LOOKS POSSIBLE...BUT MAINLY EAST OF THE FORECAST AREA ON THE MEAN OF MODEL GUIDANCE. COULD SEE A LITTLE SLOW DOWN AGAIN...BUT AT THIS POINT NOT TOO CONCERNED ON A SEVERE THREAT FRIDAY IN OUR CWA. MORE SO IT WOULD STILL BE THE HEAVY RAIN POTENTIAL. MILD TEMPERATURES TONIGHT LOOK TO CLIMB TO THE MID 70S TO 80 ON FRIDAY AS THE COLD AIR ADVECTION ENSUES ALOFT. SATURDAY AND BEYOND...GIVEN ACTIVE SHORT TERM WEATHER HAVE GONE WITH A SMART CONSENSUS BLEND DURING THIS TIME. WITH 850MB TEMPERATURES FORECAST BY THE NAM/GFS/EC OF 3C-5C OVER LAKE MI...SOME LAKE EFFECT CLOUDS ARE LIKELY SATURDAY NIGHT INTO EARLY SUNDAY INTO NW IN/NE IL AS THE WINDS VEER NNE OVER THE LAKE. OVER LAND SATURDAY NIGHT CONDITIONS SHOULD BE CLOSER TO CALM. SO THAT SPELLS WHAT COULD BE QUITE AN IMPRESSIVE TEMPERATURE CONTRAST ACROSS CHICAGOLAND AND HAVE THAT AT ALMOST 20F IN THE FORECAST SUNDAY MORNING...WITH LOWS AROUND 39F IN AURORA WHILE 58F DOWNTOWN CHICAGO. THE SURFACE HIGH MOVES EASTWARD EARLY NEXT WEEK WITH VERY GRADUALLY DEVELOPING WARM AIR ADVECTION. TEMPERATURES ARE FORECAST TO INCH UP A COUPLE DEGREES EACH DAY. MTF && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * CONVECTION MOSTLY WINDING DOWN...WITH WINDS TO VEER AND INCREASE. * MVFR CIGS AND IFR VSBYS FOR A BIT LONGER THIS MORNING. * ADDITIONAL TSRA TOWARD EVENING WITH AN APPROACHING FRONT. LENNING //DISCUSSION...UPDATED 12Z... PRIMARY CONCERNS THROUGH THE PERIOD WILL BE PERIODIC CHANCES FOR ADDITIONAL SHRA/TSRA AND SLY-SSWLY WINDS GUSTING TO 20-25 KT. THE REGION REMAINS UNDER WARM/MOIST ADVECTION WITH SLY FLOW AT THE SFC AND SWLY FLOW THROUGH THE LOWEST 10KFT ABOVE THE SFC LAYER. WHILE THE STRONGEST WARM ADVECTION AND ISENTROPIC LIFT REMAINS TO THE WEST...OVER THE UPPER MISSOURI VALLEY TO THE MIDDLE MISSISSIPPI VALLEY. THE BROAD AREA OF WARM ADVECTION AND LIFT WILL KEEP THE CHANCES FOR SCT THUNDER OVER THE AREA FOR THE NEXT FEW HOURS...HOWEVER...GIVED THE LACK OF A SPECIFIC FOCUSING MECHANISM...THE ACTIVITY WILL BE SCATTERED AND LIKELY WILL NOT IMPACT THE TERMINALS FOR A SOLID BLOCK OF TIME. SO...WILL KEEP THE VCSH AND TEMPO GROUPS IN THE FORECAST...BUT CONFIDENCE REMAINS LOW AS TO THE EXACT TIMING OF DIRECT IMPACT ON THE TERMINALS. THE OTHER SIGNIFICANT CHANCE FOR THUNDER WILL COME THIS EVENING AND THROUGH THE NIGHT AS A COLD FRONT MOVES THROUGH THE REGION. FOR THE EVENING HOURS...THE ACTIVITY...ONCE AGAIN...WILL LIKELY BE MORE SCATTERED...BUT AS THE COLD FRONT APPROACHES...THE ACTIVITY SHOULD SOLIDIFY WITH A PERIOD OF PREVAILING THUNDER LIKELY. AT THIS POINT...THE BEST CHANCE FOR PREVAILING THUNDER SHOULD BE JUST AFTER MIDNIGHT AND INTO THE EARLY MORNING HOURS. THERE SHOULD THEN BE A PERIOD OF SOME TRAILING STRATIFORM RAIN WITH LOWER END MVFR OR POSSIBLY IFR CIGS DEVELOPING FOR THE PRE-DAWN HOURS. FOR WINDS...THERE IS LITTLE CHANGE TO THE GOING FORECAST. WINDS SHOULD REMAIN SLY THROUGH THE MORNING AT ARND 10KT...AWAY FROM THUNDER. SOME LOCALLY HIGHER GUSTS ARE POSSIBLY INVOF THUNDER. WITH DAYTIME WARMING AND SOME BREAKING UP OF CLOUD COVER...HIGHER GUSTS SHOULD MIX DOWN TO THE SFC AND FREQUENT GUSTS TO ARND 20KT SHOULD PREVAIL FROM LATE MORNING THROUGH EARLY EVENING. AS THE FRONTAL TROUGH APPROACHES THE MISSISSIPPI RIVER LATER TODAY...WIND DIRECTION SHOULD VEER A LITTLE WEST OF SOUTH TO 200-210 DEGREES BEFORE SHIFTING TO NWLY WITH THE FROPA. KREIN //ORD AND MDW CONFIDENCE...UPDATED 16Z... * HIGH CONFIDENCE OF MOSTLY DRY THIS AFTERNOON UNTIL FRONTAL PRECIP ARRIVES TOWARD EVENING. * MEDIUM CONFIDENCE IN CIG/VSBY IMPROVEMENTS. * MEDIUM TO HIGH CONFIDENCE IN WIND TRENDS. LENNING //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT THROUGH WEDNESDAY...VFR. WX NIL. KREIN && .MARINE... 300 AM CDT AN AREA OF LOW PRESSURE CENTERED OVER THE EASTERN DAKOTAS WILL WEAKEN SLIGHTLY AND TRACK NORTHEAST TO WESTERN ONTARIO BY THIS EVENING. SOUTHERLY WINDS TO AROUND 25 KT WILL PERSIST OVER THE LAKE AS THE THE LOW DEEPEN FURTHER AND TRACKS NORTHEAST INTO NORTHERN QUEBEC BY SATURDAY MORNING. AN ASSOCIATED COLD FRONT WILL SWEEP ACROSS LAKE MICHIGAN FRIDAY AFTERNOON AND EVENING...WITH WINDS GRADUALLY VEERING FROM SOUTHWESTERLY TO NORTHWESTERLY AND...ULTIMATELY NORTHEASTERLY...AS A LARGE AREA OF HIGH PRESSURE BUILDS IN BEHIND THE FRONT. IN THE COLD ADVECTION BEHIND THE FRONT...NORTHWEST TO NORTH WINDS WILL REDEVELOP...WITH SOME OCCASIONAL GUSTS TO 30KT POSSIBLE FRIDAY NIGHT. KREIN && .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 1040 AM CDT Thu Sep 19 2013 .DISCUSSION... ISSUED 1040 AM CDT Thu Sep 19 2013 Warm front has lifted well to the northeast of central Illinois this morning, leaving behind partly to mostly sunny skies and very warm temps in the upper 70s and lower 80s. Convection continues to fire along the edge of the strengthening cap in the warm sector, mainly from southern Lake Michigan S/SE across Indiana into the Ohio River Valley. As warm air aloft spreads further east, this activity will continue to shift further away from Illinois this afternoon. End result will be a hot and mainly dry day, with perhaps a few isolated thunderstorms. Afternoon high temps will reach the upper 80s and lower 90s. Better thunderstorm chances will arrive by late evening across the Illinois River Valley. Latest HRRR shows a line of convection developing along an advancing cold front and pushing toward the Illinois River by around 03z. This activity should continue eastward in a weakening state overnight. Barnes && .AVIATION... ISSUED 655 AM CDT Thu Sep 19 2013 An area of showers and thunderstorms associated with a small MCS will mainly stay east of the central IL terminal airports this morning from Vermilion county ese into Indiana. Carried VCSH over eastern IL airports til 14-15Z with light fog/haze bringing visibilities of 4-6 miles. Isolated convection possible this afternoon and early evening as airmass become more unstable, but coverage too limited to pinpoint down in the TAFs. VFR conditions should generally prevail today and this evening with scattered cumulus clouds and scattered-broken mid level clouds. A cold front extending from 1001 mb low pressure over se part of Lake Winnipeg through western MN thru far nw corner of IA into se Nebraska and nw KS. Cold front slated to push se to near the IL river by PIA around 12Z/7 am Fri. A band of showers and thunderstorms to accompany the cold front and spread se across central IL overnight, reaching PIA after 05Z/midnight and DEC and CMI after 09Z/4 am. MVFR ceilings and visibilities possible with convection overnight. SSW winds around 10 kts early this morning to increase to 10-15 kts with gusts 18-23 kts by 15Z and continue through early evening, then be 10-14 kts tonight and gradually veer sw overnight. 07 && .PREV DISCUSSION... ISSUED 251 AM CDT Thu Sep 19 2013 Developing storm system over the northern Plains to be the main issue for the forecast in the Midwest for this package. High pressure over the Atlantic seaboard slowly sliding eastward with southerly flow ramping up over the region in the middle of the country. Sunshine and WAA will send temperatures well above normal ahead of the storm system. All the warm air in place will provide instability for advancing chances of thunderstorms through tonight and tomorrow. Biggest issues for the forecast revolve around the timing of the front vs. max heating, and speed of the front itself. Ongoing convection already starting to hint that the mesoscale influences with prefrontal trofs and outflow boundaries will more than likely complicate the forecast of the details. Best chances for precip tonight and through tomorrow. SHORT TERM...Today and tomorrow... Hot today with the ridge expanding into the Midwest. Warmest midlevels in western CWA but will likely be countered somewhat by advancing clouds. However, front will hold off enough to see upper 80s over majority of the area. Cold front has slowed progression to tomorrow but convection ahead of the front and associated cold pools will mask some of the distinction of the leading edge. Plenty of instability in the region...but the cold front being delayed a bit results in the FA barely clipped by the slight risk outlook to the northwest for tonight. Frontal progression tomorrow to be slower, and already in rain and cloud cover from the overnight will likely inhibit intense storm development. So far tomorrow remains in a general thunder. Overnight Friday will see a clearing from west to east. Will need to keep an eye on guidance NW of Interstate 55 corridor for rapid clearing may result in a need for an adjustment of the lows down a couple degrees. LONG TERM...Saturday through Wednesday... Milder weather and dry through the extended. High pressure dominates the eastern half of the country and temperatures remain milder and closer to normal...with heat building again under a thermal ridge in the southwestern US. With southwesterly flow kicking in next week Tues, the extended could see some warmer temps as time draws nearer should the pattern persist. Guidance is still being pulled to 70s by climatology at this point. HJS && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
107 PM EDT THU SEP 19 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 355 AM EDT THU SEP 19 2013 AN UPPER RIDGE WILL BE ACROSS CENTRAL INDIANA THROUGH THIS EVENING AS WARM MOIST AND UNSTABLE AIR MOVES IN FROM THE SOUTH ON THE BACK SIDE OF SURFACE HIGH PRESSURE ACROSS THE EASTERN STATES. THERE IS A CHANCE OF THUNDERSTORMS MAINLY THIS AFTERNOON AND EVENING AS WEAK WAVES MOVE OVERTOP THE RIDGE AND THE ATMOSPHERE BECOMES VERY UNSTABLE. THUNDERSTORMS WILL BECOME WIDESPREAD FRIDAY AND FRIDAY NIGHT AS A COLD FRONT DROPS SOUTHEAST ACROSS CENTRAL INDIANA FRIDAY NIGHT. THERE COULD BE A FEW LINGERING MORNING THUNDERSTORMS SATURDAY MORNING ACROSS SOUTHEASTERN PARTS OF CENTRAL INDIANA. OTHERWISE...HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT ALLOW FOR COOLER TEMPERATURES AND DRY WEATHER THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /REST OF TODAY AND TONIGHT/... ISSUED AT 1008 AM EDT THU SEP 19 2013 .UPDATE... NUMEROUS SHOWERS AND THUNDERSTORMS WILL LAST THROUGH MIDDAY AND... AND INTO EARLY AFTERNOON OVER EASTERN SECTIONS OF THE REGION. RAPID REFRESH THIS CONVECTION UNTIL MID AFTERNOON OVER THE EAST. AFTER THAT WILL CONTINUE WITH THE SCENARIO THAT THUNDERSTORMS WILL DIMINISH BY LATE AFTERNOON PER NAM AND RAPID REFRESH MODELS. IN REGARDS TO TEMPERATURES LATEST RAP INDICATES HIGH TEMPERATURES APPROACHING 90 FAR WEST WHERE THERE WILL BE MORE SUNSHINE THIS AFTERNOON TO RAISE TEMPERATURES. OVER THE EAST CLOUDS AND LINGERING PRECIPITATION MAY KEEP HIGH TEMPERATURES CLOSER TO 80. NO CHANGES WILL BE MADE AT THIS TIME TONIGHT. NAM SUGGESTS INDICATES THERE SHOULD BE A LULL IN ANY THUNDERSTORM ACTIVITY MOST OF TONIGHT AND THEN CHANCES INCREASING TOWARDS DAYBREAK WEST AS COLD FRONT APPROACHES. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... ISSUED AT 355 AM EDT THU SEP 19 2013 MAIN CHALLENGE TO THE SHORT TERM WILL CONTINUE TO BE POPS ALONG WITH TIMING OF SHOWER ACTIVITY OUT OF THE FORECAST AREA. MODELS ARE NOW IN GOOD AGREEMENT ON FRONTAL TIMING AND WILL GO WITH A BLEND THAT SUGGESTS THE APPROACHING STRONG NORTHERN UPPER TROUGH WILL FORCE THE FRONT TO NEAR LAFAYETTE BY 00Z SATURDAY AND THEN SOUTHEAST OF CENTRAL INDIANA AFTER 09Z SATURDAY. THE SPC DAY2 OUTLOOK AS THROWN ROUGHLY OUR SOUTHEASTERN HALF OF THE FORECAST IN A SLIGHT RISK OF SEVERE WEATHER FOR FRIDAY AFTERNOON AND EVENING. THIS SEEMS REASONABLE AS THE LOW LEVEL JET WILL BE OVER THIS AREA AFTER 18Z FRIDAY...AND WITH PLENTY OF WIDESPREAD ACTIVITY EXPECTED ACROSS THE NORTHWEST HALF OF THE FORECAST AREA DURING THE MORNING AND AFTERNOON...THAT PART OF THE FORECAST AREA WILL HAVE A HARD TIME DESTABILIZING AS MUCH AS THE SOUTHEAST. EVEN SOUTHEAST...ONLY EXPECT AN ISOLATED SEVERE STORM OR TWO WITH MARGINAL SHEAR AND INSTABILITY. WILL GO WITH OCCASIONAL POPS FRIDAY SPREADING SOUTHEAST DURING THE AFTERNOON AND NIGHT. WILL LEAVE SMALL CHANCE LINGER SHOWERS SATURDAY MORNING...OTHERWISE...HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT WHICH WILL BRING DRY WEATHER IN FOR THE REST OF THE WEEKEND ALONG WITH COOLER TEMPERATURES PER MOS AND MODEL BLEND. HEAVY RAIN WILL CONTINUE TO BE A THREAT THROUGH FRIDAY NIGHT WITH PRECIPITABLE WATER VALUES NOT DROPPING MUCH UNTIL OVERNIGHT FRIDAY NIGHT. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... ISSUED AT 355 AM EDT THU SEP 19 2013 DRY FORECAST THIS PERIOD WITH SEASONABLE TEMPERATURES. GFS AND ECMWF DEPICT A CUT OFF UPPER LOW MOVING THROUGH THE APPALACHIANS EARLY IN THE PERIOD WHILE RIDGING ALOFT AND STRONG SUBSIDENCE OVER THE MISSISSIPPI RIVER VALLEY PROVIDES A NORTHERLY FLOW OF AIR AS IT SLOWLY BUILDS EAST DURING THE PERIOD. AS THE RIDGE MOVES EAST OVER INDIANA BY THE MIDDLE OF NEXT WEEK...TEMPS WILL SLOWLY MODERATE TO SLIGHTLY ABOVE NORMAL AS RETURN FLOW BEGINS. && .AVIATION /DISCUSSION FOR 191800Z TAF ISSUANCE/... ISSUED AT 1259 PM EDT THU SEP 19 2013 CONVECTION HAS MOVED EAST OF THE SITES AT THIS POINT. WHILE SOME POP UP DEVELOPMENT IS POSSIBLE YET THIS AFTERNOON/EVENING BOTH TIMING AND PLACEMENT ARE UNCERTAIN ENOUGH TO LEAVE OUT AT THIS TIME. MODEL SOUNDINGS SHOW PRETTY GOOD INVERSION AND LOW LEVEL SATURATION OVERNIGHT BUT WINDS SHOULD STAY BETWEEN 5-10 KTS SO FOR NOW WILL JUST DROP OUTLYING SITES TO MVFR FOG FOR A FEW HOURS AFTER 9Z. A COLD FRONT WILL APPROACH TOMORROW AND WILL BRING THUNDERSTORMS WITH IT BUT EXACT TIMING IS STILL FAR ENOUGH OUT TO JUST INCLUDE A PROB30 AT THIS TIME. LEFT THIS OUT AT KBMG AS IT WILL BE BEYOND THE FORECAST PERIOD THERE. ALSO EXPECT TO SEE SOME WIND GUSTS UP TO AROUND 20 KTS BY MID MORNING OUT OF THE SOUTHWEST AHEAD OF THE FRONT. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MK NEAR TERM...JH SHORT TERM...MK LONG TERM....JAS AVIATION...CP VISIT US AT HTTP://WWW.WEATHER.GOV/IND FOLLOW US ON TWITTER AND YOUTUBE AT: WWW.TWITTER.COM/NWSINDIANAPOLIS WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
223 PM CDT Thu Sep 19 2013 ...Updated long term section... .SYNOPSIS... ISSUED AT 1206 PM CDT THU SEP 19 2013 At 12z Thursday a -18c 500mb trough was located over the northern Rockies with a 300mb jet streak extending from the based of this upper trough into southern Manitoba. Across the panhandle of Texas a 40-50kt jet was observed with the left exit region of this jet steak located near the Oklahoma panhandle. this related well to some early morning convection which developed near a surface trough of low pressure that extended from the panhandle of Oklahoma into north central Kansas. A surface cold front at 12z extended from eastern Nebraska, across northwest Kansas into east central Colorado. && .SHORT TERM...(This evening through Friday) ISSUED AT 145 PM CDT THU SEP 19 2013 Based on 18z surface analysis the surface cold front was progressing across western Kansas slightly quicker than what the 12z GFS and 12z NAM suggested. The latest HRRR and RAP seems to be tracking the front a little better earlier this afternoon so will follow these models for the frontal location between 21z and 00z. Convection is expected to begin to initiate near this boundary late day given the afternoon instability progged and improving upper level dynamic from the left entrance region of an weak upper level jet crossing western Oklahoma. The current distribution of precipitation chances across south central Kansas still looks on track so other than adjusting the location of the front, no major adjustments to the previous forecast is anticipated late today and early tonight. SPC mesoanalysis indicating better 0-6km shear late today so at this time can not rule the chance of a few thunderstorms near the Oklahoma border. Quarter size hail, gusty winds and periods of heavy rainfall currently appear to be the main hazard late today. Convection across south central Kansas and near the Oklahoma border after sunset will taper off towards midnight and skies are expected to begin to clear from north to south. Lows tonight will be cooler than the past few nights and based on expected 09z to 12z dewpoints will keep lows mainly in the 50s. High pressure at the surface will build into western Kansas on Friday as an upper level ridge builds into the western high plains from the west. The highs on Friday are expected to climb only into the mid to upper 70s given that both the NAM and GFS suggest a 3c- 6c decrease in 925mb-850mb temperature from 00z Thursday to 00z Friday. .LONG TERM...(Friday night through Thursday) ISSUED AT 222 PM CDT THU SEP 19 2013 Mostly clear skies and dry conditions are anticipated Friday night through Sunday morning as an upper level ridge moves over the Central Plains, mid levels of the atmosphere remain dry, and a dome of high pressure slides southeast of the area. The only exception to this will be the possibility of a few cumulus clouds around peak heating. Winds will generally be from the northeast Friday night shifting to more of a southerly direction Saturday into Sunday morning. Meanwhile, an upper level shortwave will be moving through the Western United States Saturday then into the Central Rockies Sunday. Mid to upper level moisture will be on the increase during the day Sunday allowing for a few clouds to form. This shortwave will also help push a cold front through the area Sunday night. A few thunderstorms will be possible along and ahead of this front with winds shifting to more of a southerly direction behind it. Cold air advection will be short lived with this front as winds shift back to a southerly direction Monday night through Wednesday. Flow aloft becomes more zonal (west to east) Monday night through Tuesday then more of a southwest direction Wednesday as the next shortwave digs into the Intermountain West. Mostly clear skies and dry conditions are expected over Western Kansas during this timeframe with lee troughing strengthening across eastern Colorado. Seasonable temperatures are expected Saturday with highs around 80 degrees and lows Saturday and Sunday morning in the 50s. Highs are then expected to reach into the lower 80s Sunday and Monday with mid 80s Tuesday and Wednesday. Lows are forecasted to range from the upper 50s to mid 60s. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) ISSUED AT 1206 PM CDT THU SEP 19 2013 The cold front that was located across northwest Kansas at 12z Thursday was at 17z located just just southeast of Dodge City and Hays. Gusty north to northwest winds behind this front will decrease to less than 10kts after sunset as an area of high pressure at the surface beings to build into the area from northwest. Cooler and drier air will begin to work its way into western Kansas overnight but there will be a chance for a brief period of low VFR cigs between 03z and 06z based on the moisture profiles from the 12z NAM bufr soundings in the 850-800mb level. && .PRELIMINARY POINT TEMPS/POPS... DDC 55 77 51 80 / 20 0 0 0 GCK 53 76 51 81 / 10 0 0 0 EHA 52 75 53 81 / 20 0 0 0 LBL 55 78 52 82 / 40 0 0 0 HYS 52 75 51 81 / 10 0 0 0 P28 60 80 53 80 / 90 10 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Burgert SHORT TERM...Burgert LONG TERM...Hovorka_42 AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
147 PM CDT Thu Sep 19 2013 ...Updated short term discussion... .SYNOPSIS... ISSUED AT 1206 PM CDT THU SEP 19 2013 At 12z Thursday a -18c 500mb trough was located over the northern Rockies with a 300mb jet streak extending from the based of this upper trough into southern Manitoba. Across the panhandle of Texas a 40-50kt jet was observed with the left exit region of this jet steak located near the Oklahoma panhandle. this related well to some early morning convection which developed near a surface trough of low pressure that extended from the panhandle of Oklahoma into north central Kansas. A surface cold front at 12z extended from eastern Nebraska, across northwest Kansas into east central Colorado. && .SHORT TERM...(This evening through Friday) ISSUED AT 145 PM CDT THU SEP 19 2013 Based on 18z surface analysis the surface cold front was progressing across western Kansas slightly quicker than what the 12z GFS and 12z NAM suggested. The latest HRRR and RAP seems to be tracking the front a little better earlier this afternoon so will follow these models for the frontal location between 21z and 00z. Convection is expected to begin to initiate near this boundary late day given the afternoon instability progged and improving upper level dynamic from the left entrance region of an weak upper level jet crossing western Oklahoma. The current distribution of precipitation chances across south central Kansas still looks on track so other than adjusting the location of the front, no major adjustments to the previous forecast is anticipated late today and early tonight. SPC mesoanalysis indicating better 0-6km shear late today so at this time can not rule the chance of a few thunderstorms near the Oklahoma border. Quarter size hail, gusty winds and periods of heavy rainfall currently appear to be the main hazard late today. Convection across south central Kansas and near the Oklahoma border after sunset will taper off towards midnight and skies are expected to begin to clear from north to south. Lows tonight will be cooler than the past few nights and based on expected 09z to 12z dewpoints will keep lows mainly in the 50s. High pressure at the surface will build into western Kansas on Friday as an upper level ridge builds into the western high plains from the west. The highs on Friday are expected to climb only into the mid to upper 70s given that both the NAM and GFS suggest a 3c- 6c decrease in 925mb-850mb temperature from 00z Thursday to 00z Friday. .LONG TERM...(Friday through Wednesday) ISSUED AT 311 AM CDT THU SEP 19 2013 A deep upper level shortwave trough will be moving out of the northern and central plains by Friday morning. The associated surface cold front will be well to the southeast of western Kansas with clear skies and cooler temperatures in its wake. The medium range models show a fairly progressive upper level pattern across North America through the remainder of the extended period. An upper level ridge will move east over the central High Plains Saturday and Sunday before another strong shortwave trough moves out of the Rockies into the central High Plains Sunday night and Monday. The atmosphere is not progged to be overly unstable but the GFS and ECMWF both show a 70 knot upper level jet propagating across the Oklahoma/Texas panhandles Sunday night. With western Kansas under the left exit region of this jet, think that the going 30-40 percent pops for thunderstorms looks reasonable. Upper level ridging builds back over the central part of the country through midweek ahead of another strong wave that digs into the western states. We should see dry weather through midweek before precipitation chances increase by next weekend. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) ISSUED AT 1206 PM CDT THU SEP 19 2013 The cold front that was located across northwest Kansas at 12z Thursday was at 17z located just just southeast of Dodge City and Hays. Gusty north to northwest winds behind this front will decrease to less than 10kts after sunset as an area of high pressure at the surface beings to build into the area from northwest. Cooler and drier air will begin to work its way into western Kansas overnight but there will be a chance for a brief period of low VFR cigs between 03z and 06z based on the moisture profiles from the 12z NAM bufr soundings in the 850-800mb level. && .PRELIMINARY POINT TEMPS/POPS... DDC 55 77 50 80 / 20 0 0 0 GCK 53 76 50 81 / 10 0 0 0 EHA 52 75 52 81 / 20 0 0 0 LBL 55 78 51 81 / 40 0 0 0 HYS 52 75 50 80 / 10 0 0 0 P28 60 80 52 80 / 90 10 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Burgert SHORT TERM...Burgert LONG TERM...Gerard AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1122 AM MDT THU SEP 19 2013 .UPDATE... ISSUED AT 909 AM MDT THU SEP 19 2013 AREA OF PRECIPITATION CONTINUES TO MARCH EAST AHEAD OF A COLD FRONT THAT HAS MOVED THROUGH THE WEST HALF OF THE AREA SO FAR. BEST CHANCES FOR RAINFALL CONTINUE TO LOOK TO BE OVER THE FAR EAST AS LIFT FROM THE COLD FRONT COMBINED WITH AN UPPER LEVEL TROUGH WILL MOVE THROUGH AROUND NOON. BEHIND THE FRONT NORTHERLY WINDS HAVE BECOME GUSTY...RANGING FROM 20-30 MPH WITH SOME GUSTS NEARING 40 MPH IN FAR NORTHEAST COLORADO. THE GUSTS SHOULD START TO DECLINE BY THE EARLY AFTERNOON AS THE SURFACE PRESSURE GRADIENT BEHIND THE FRONT SLACKENS. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 358 AM MDT THU SEP 19 2013 FORECAST PROBLEMS WILL BE PRECIPITATION CHANCES TODAY...HOW COOL TO MAKE HIGHS AND LOWS THROUGH FRIDAY NIGHT AND HOW MUCH TO WARM THINGS UP ON SATURDAY. SATELLITE SHOWING AN ACTIVE FLOW FROM THE PACIFIC INTO NORTH AMERICA. THE FLOW WAS AMPLIFYING SOME OVER THE PACIFIC... ESPECIALLY ALONG THE WEST COAST. ONE SYSTEM IS PUSHING EAST ALONG THE U.S AND CANADIAN BORDER. OUTFLOW FROM THUNDERSTORM CLUSTER TO OUR NORTH HAS PUSHED THROUGH THE AREA WITH A COLD FRONT APPROACHING FROM THE NORTHWEST. AT JET LEVEL...THE SREF WAS DOING A LITTLE BETTER WITH THE JET DEPICTION OVER OUR AREA. AT MID LEVELS...MODELS WERE HAVING A LITTLE TROUBLE THE SPEED AND AMPLITUDE OF THE NORTHERN LOW. AT THIS TIME IT APPEARS THE GFS AND UKMET WERE DOING A LITTLE BETTER THAN THE ECMWF AND CANADIAN. THE RUC WAS CATCHING THE INITIAL WIND FIELD THE BEST WITH THE ECMWF NOT TOO FAR BEHIND. THE UKMET AND GFS WERE DOING A LITTLE BETTER THAN THE OTHER OUTPUT ON THE LOW LEVEL THERMAL FIELD. TODAY/TONIGHT...INTERESTING PRECIPITATION FORECAST. INITIAL ROUND OF THUNDERSTORMS WERE CAUSED BY INITIAL SURFACE TROUGH AND OUTFLOW BOUNDARY FROM CLUSTER OF THUNDERSTORMS THAT MOVED TO THE NORTH OF OUR FORECAST AREA. HOWEVER ADDITIONAL DEVELOPMENT IS NOW OCCURRING IN ADVANCE OF COLD FRONT WHICH IS VERY NEAR THE NORTHWEST CORNER OF THE FORECAST AREA. ALSO AT THIS TIME...MAIN SHORTWAVE TROUGH ROTATING AROUND NORTHERN UPPER LOW IS BEGINNING TO MOVE IN FROM THE WEST. ALSO THE RIGHT REAR QUADRANT OF THE JET IS NEAR/OVER THE WESTERN END OF THE FORECAST. DURING THE DAY THEY ALL HANDLE IT DIFFERENTLY. HOWEVER...BY THE END OF THE AFTERNOON INTO THE EARLY AFTERNOON...THE RIGHT REAR QUADRANT IS OVER OR NEAR THE EASTERN END OF THE AREA. IN ADVANCE OF ALL THESE FEATURES THERE APPEARS ENOUGH ELEVATED CAPE WITH FAVORABLE THETA-E LAPSE RATES TO ALLOW FOR A GOOD RESPONSE TO THE LIFT. AT THIS TIME IT LOOKS LIKE THE FAVORED AREA FOR THUNDERSTORMS IS ALONG AND EAST OF THE COLORADO BORDER...GETTING HIGHER AS YOU GO EAST. KEPT THIS GENERAL IDEA FROM THE DAY SHIFT BUT RAISED POPS SLIGHTLY FURTHER EAST. THUNDERSTORMS LOOK TO BE DONE BY LATE IN THE DAY. DEFINITELY LOOKS COOLER. THE QUESTION IS HOW MUCH. THE AMOUNT OF TEMPERATURE CHANGE OVER YESTERDAY WOULD YIELD SLIGHTLY COOLER TEMPERATURES THAN WHAT I HAVE IN THERE NOW. DID MAKE SLIGHT ADJUSTMENTS COOLER IN LINE WITH THE BIAS ADJUSTMENT TO THE 850 MB TEMPERATURES. THIS TENDED TO BE IN THE MIDDLE OF THE GUIDANCE. WILL BE A RATHER COOL NIGHT TONIGHT WITH LITTLE CLOUD COVER AND LIGHT WINDS. MODELS DIFFER ON WHERE THE LIGHTEST WINDS WILL BE. AT THIS TIME IT LOOKS THEY WILL BE IN THE WESTERN AND NORTHERN SECTIONS AND ADJUSTED ACCORDINGLY. FRIDAY/FRIDAY NIGHT...MID/UPPER RIDGE BUILDING INTO THE AREA WILL MAKE FOR DRY CONDITIONS AND LITTLE TO NO CLOUD COVER. SURFACE RIDGE JUST PULLING OFF TO THE EAST DURING THE DAY WITH LIGHT AND VARIABLE WINDS...ESPECIALLY IN THE EAST. MODELS ARE INDICATING TEMPERATURES NEAR WHAT THEY ARE TO BE TODAY. ONLY MADE SLIGHT ADJUSTMENTS BASED ON THAT. SOME DIFFERENCES IN HOW COOL TO MAKE THE MINS. THE NAM STARTS WARM ADVECTION MUCH FASTER WITH THE OTHER MODELS SLOWER. IT SHOULD BE WARMER BUT AM NOT GOING AS WARM AS THE NAM. SATURDAY/SATURDAY NIGHT...MID/UPPER LEVEL RIDGE STARTS PUSHING EAST LATE IN THE DAY AND ESPECIALLY IN THE NIGHT WITH SOUTHWEST FLOW ALOFT DEVELOPING OVER THE AREA. THIS RIDGE PLUS VERY DRY/WELL MIXED AIR MASS ALOFT WILL KEEP CONDITIONS DRY...DESPITE THE FACT AN UPPER JET APPROACHES THE WESTERN PORTIONS OF THE AREA LATE IN THE NIGHT. SHOULD BE WARMER...QUESTION IS HOW MUCH WARMER. NAM CONTINUES TO BE THE MOST AGGRESSIVE WITH THIS. WIND FIELD AND CONSENSUS OF 850 MB TEMPERATURES SUPPORT GOING COOLER. THIS IS CLOSE TO WHAT CURRENT FORECAST HAS IN THERE AND ONLY MADE SLIGHT ADJUSTMENTS. .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 300 AM MDT THU SEP 19 2013 A SHORTWAVE TROUGH WILL QUICKLY MOVE THROUGH SUNDAY NIGHT. THE STRONGEST FORCING WILL BE NORTH OF THE FORECAST AREA ACROSS NEBRASKA WHERE GFS ENSEMBLE MEAN QPF VALUES ARE HIGHEST. ISOLATED TO SCATTERED CONVECTION SHOULD IMPACT THE WESTERN PORTION OF THE FORECAST AREA BY SUNDAY EVENING AND THEN OVERSPREAD THE REST OF THE AREA OVERNIGHT. THE GREATEST RAIN CHANCES AND POTENTIAL FOR THE HIGHEST RAINFALL AMOUNTS WILL BE OVER ROUGHLY THE NORTHEASTERN HALF OF THE FORECAST AREA. SLIGHTLY COOLER TEMPERATURES WILL ARRIVE BEHIND THIS SHORTWAVE AND ASSOCIATED COLD FRONT ON MONDAY BUT COLD AIR ADVECTION IN THE WAKE OF THIS SYSTEM IS BRIEF AND INSIGNIFICANT. STRONG EAST TO WEST ORIENTED MID/UPPER FLOW WILL BE SITUATED OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS ON TUESDAY. BY MID WEEK A LARGE TROUGH EVOLVES OVER THE WESTERN CONUS. MODELS DIFFER ON HOW THIS TROUGH WILL EVOLVE BY MID WEEK WITH GFS AND ECMWF DIFFERING ON THE POSITION OF CLOSED UPPER LOW...MEANWHILE GFS ENSEMBLE MEAN DEPICTS A MORE OPEN/PROGRESSIVE TROUGH. IN EITHER SCENARIO...SIGNIFICANT IMPACTS TO OUR AREA ARE NOT EXPECTED THROUGH THE END OF THE EXTENDED PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1119 AM MDT THU SEP 19 2013 VFR CONDITIONS FORECAST FOR THE 18Z TAFS. CURRENT LOW CLOUDS OVER KGLD WILL MOVE EAST AHEAD OF THE MID LEVEL TROUGH AXIS. GUSTY WINDS WILL DECLINE GRADUALLY THROUGH EARLY AFTERNOON...BECOMING LIGHTER BY MID AFTERNOON THEN LIGHT BY EARLY EVENING. THE LIGHT WINDS WILL CONTINUE THROUGH THE REST OF THE PERIOD DUE TO A SURFACE HIGH PRESSURE BUILDING OVER THE AREA TONIGHT/FRIDAY. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JTL SHORT TERM...BULLER LONG TERM...BRB AVIATION...JTL
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1210 PM CDT Thu Sep 19 2013 ...Updated synopsis and aviation discussion... .SYNOPSIS... ISSUED AT 1206 PM CDT THU SEP 19 2013 At 12z Thursday a -18c 500mb trough was located over the northern Rockies with a 300mb jet streak extending from the based of this upper trough into southern Manitoba. Across the panhandle of Texas a 40-50kt jet was observed with the left exit region of this jet steak located near the Oklahoma panhandle. this related well to some early morning convection which developed near a surface trough of low pressure that extended from the panhandle of Oklahoma into north central Kansas. A surface cold front at 12z extended from eastern Nebraska, across northwest Kansas into east central Colorado. && .UPDATE... ISSUED AT 844 AM CDT THU SEP 19 2013 Scatted showers and even a few isolated thunderstorms will continue across western and north central Kansas as an upper level disturbance based the nam 450mb- 400mb pv lifts northeast across western Kansas. HRRR appears to have a decent handle on this so will lean in that direction for precipitation chances through the early afternoon. Thunderstorms still appear become more widespread across south central Kansas during the mid to late afternoon as a cold front moves into south central Kansas, late day instability, and the location of the left exit region of an upper level jet at 00z Friday. Also trended towards a non diurnal trend in temperatures this afternoon behind the cold front as it crosses western Kansas. && .SHORT TERM...(Today and tonight) ISSUED AT 212 AM CDT THU SEP 19 2013 Short range models indicate the upper level trough kicking out of the Rockies into the Northern Plains today setting up shower and thunderstorm chances across the Upper Midwest southwestward into the Central Plains, including portions of central and western Kansas. As the upper level trough moves into the Dakotas and Nebraska, an attendant cold front will push southeastward into western Kansas late this morning into the afternoon. Meanwhile, a +85kt upper level jet is projected to climb northeast out of the desert southwest into western and central Kansas from this afternoon into this evening. Along with more favorable dynamic support aloft, steepening mid level lapse rates and increased instability will be enough to support thunderstorm development along and ahead of the cold front as it begins to push further southeast into more favorable moisture across central Kansas and eastern portions of southwest Kansas. Although vertical shear profiles are not exactly ideal, CAPE values in excess of 2000 J/KG ahead of the front will be enough to support strong to marginally severe thunderstorms...mainly southeast of a Hays to Liberal line. The potential for heavy rainfall exists as well with NAM/GFS model soundings showing PW values up around 1.5 inches. Temperatures are expected to climb back up into the lower 90s(F) across south central Kansas where the frontal passage isn`t likely to occur until late this afternoon. Otherwise, look for highs up into the upper 70s(F) and 80s(F) behind the front with the cooler temperatures across west central Kansas. Lows generally down into the 50s(F) are likely tonight as much cooler air filters south into western Kansas overnight. .LONG TERM...(Friday through Wednesday) ISSUED AT 311 AM CDT THU SEP 19 2013 A deep upper level shortwave trough will be moving out of the northern and central plains by Friday morning. The associated surface cold front will be well to the southeast of western Kansas with clear skies and cooler temperatures in its wake. The medium range models show a fairly progressive upper level pattern across North America through the remainder of the extended period. An upper level ridge will move east over the central High Plains Saturday and Sunday before another strong shortwave trough moves out of the Rockies into the central High Plains Sunday night and Monday. The atmosphere is not progged to be overly unstable but the GFS and ECMWF both show a 70 knot upper level jet propagating across the Oklahoma/Texas panhandles Sunday night. With western Kansas under the left exit region of this jet, think that the going 30-40 percent pops for thunderstorms looks reasonable. Upper level ridging builds back over the central part of the country through midweek ahead of another strong wave that digs into the western states. We should see dry weather through midweek before precipitation chances increase by next weekend. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) ISSUED AT 1206 PM CDT THU SEP 19 2013 The cold front that was located across northwest Kansas at 12z Thursday was at 17z located just just southeast of Dodge City and Hays. Gusty north to northwest winds behind this front will decrease to less than 10kts after sunset as an area of high pressure at the surface beings to build into the area from northwest. Cooler and drier air will begin to work its way into western Kansas overnight but there will be a chance for a brief period of low VFR cigs between 03z and 06z based on the moisture profiles from the 12z nam bufr soundings in the 850-800mb level. && .PRELIMINARY POINT TEMPS/POPS... DDC 85 55 78 50 / 30 30 0 0 GCK 80 53 76 50 / 30 10 0 0 EHA 82 52 76 52 / 40 10 0 0 LBL 85 55 79 51 / 30 20 0 0 HYS 80 52 75 50 / 30 10 0 0 P28 92 60 80 52 / 80 80 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Burgert SYNOPSIS...Burgert SHORT TERM...JJohnson LONG TERM...Gerard AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
328 PM EDT THU SEP 19 2013 .SYNOPSIS... ALTHOUGH SHOWERS ARE POSSIBLE THROUGH FRIDAY...WIDESPREAD RAIN IS NOT EXPECTED TO FALL UNTIL FRIDAY NIGHT AND SATURDAY WITH THE ARRIVAL OF A STRONG COLD FRONT. && .NEAR TERM /THROUGH FRIDAY/... STARTING TO LOOK AS IF PRECIPITATION WILL JUST NOT GET STARTED THIS AFTERNOON. SHOWERS HAVE MANAGED TO STAY ACROSS CENTRAL OHIO AND WESTERN WEST VIRGINIA...NOT ENTERING OUR FORECAST AREA. RAP MODEL SHOWS A VERY SMALL SHORTWAVE OVER OHIO DISSIPATING AS IT MOVES TO THE SOUTHEAST THIS AFTERNOON...AND EXCEPT FOR THE FAR WESTERN OHIO COUNTIES...CONDITIONS SHOULD REMAIN DRY WELL PAST MIDNIGHT. COULD START TO SEE SOME CONVECTION OVERNIGHT...BUT REALLY THINK THAT DIURNAL TIMING SHOULD STILL PUSH MOST PRECIPITATION UNTIL FRIDAY AFTERNOON. HIGH-RESOLUTION MODELS ARE SHOWING VERY LITTLE PRECIPITATION AHEAD OF THE COLD FRONT EVEN DURING THE AFTERNOON. SPC CONVECTIVE OUTLOOK SHOWS A POSSIBILITY FOR A STRONG TO SEVERE STORM FRIDAY...BUT BOTH INSTABILITY AND WIND SHEAR SHOULD REMAIN MARGINAL. EVEN WITHOUT PRECIPITATION...THINK THAT MOIST LOW LEVELS COULD ALLOW FOR ANOTHER ROUND OF LOW CLOUDS TO DEVELOP AFTER MIDNIGHT AND PERSIST INTO THE MORNING HOURS. THIS WOULD SQUASH MUCH OF THE DIURNAL TEMPERATURE CURVE...ALLOWING FOR ABOVE NORMAL LOW TEMPERATURES...WITH HIGHS REACHING INTO THE UPPER 70S WITH MOSTLY HIGH CLOUDS TOMORROW. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... MODEL SOLUTIONS CONTINUE TO GENERALLY VARY LESS THAN 6 HOURS WITH THE TIMING OF THE FRONTAL PROGRESSION ACROSS THE AREA ON SATURDAY. IN GENERAL...MODELS FAVOR A PASSAGE IN OHIO IN THE MORNING...AND PENNSYLVANIA/WEST VIRGINIA IN THE AFTERNOON. THE FORECAST WAS ADJUSTED A BIT TOWARD THE SLOWER END OF THE GUIDANCE OWING TO A SECONDARY VORT MAXIMA DIGGING INTO THE BASE OF THE MID-LEVEL TROUGH SUPPORTING THE FRONTAL PROGRESSION. WITH THIS TYPE OF DEVELOPMENT...A SLOWER SOLUTION GENERALLY VERIFIES. ADDITIONALLY...THE 12Z GFS/ECMWF/CANADIAN ALL CAME IN A TAD SLOWER THAN THE NAM AND THEIR PREVIOUS CYCLE COUNTERPARTS...SO HANGING ONTO HIGHER POPS INTO THE AFTERNOON STILL SEEMS PRUDENT. CONVECTIVE DEVELOPMENT ALONG THE FRONT STILL SEEMS RATHER UNLIKELY. UPPER JET STREAK COUPLING...WHILE STRONG OVER INDIANA FRIDAY EVENING AND NIGHT...QUICK BECOMES LESS IMPRESSIVE ON SATURDAY AS THE SECONDARY VORT DIGS INTO THE TROUGH. AS THIS OCCURS...THE NORTHER JET STREAK QUICKLY BECOMES DISASSOCIATED FROM THE SOUTHERN JET STREAK BY SATURDAY AFTERNOON. AS A CONSEQUENCE...UPPER FORCING FADES A BIT AS THE FRONT PROGRESSES ACROSS THE AREA. ADDITIONALLY...SIGNIFICANT ADVANCE CLOUD COVER SHOULD PRECLUDE SIGNIFICANT INSTABILITY GENERATION. FURTHERMORE...WITH THE DISSOCIATION OF THE LARGE SCALE FLOW IN THE MID AND UPPER LEVELS...SHEAR VALUES ACTUALLY DECREASE IN OUR SECTOR OF THE FRONT THROUGH THE DAY SATURDAY. AS SUCH...WITH LITTLE INSTABILITY AND WEAKENING SHEAR...THUNDERSTORM CHANCES DO NOT SEEM LIKELY WITH FADING UPPER LEVEL SUPPORT. HOWEVER...WHILE NOT LIKELY...LOW LEVEL CONVERGENCE ALONG THE FRONT AND SOME AMOUNT OF FRONTOGENETICAL FORCING MAY GIVE ENOUGH OF A KICK TO WORK WITH THE ROUGHLY 300 J/KG OF 1000-700 MB MUCAPE IMMEDIATELY ALONG THE FRONT. TO COVER THIS...SLIGHT CHANCES OF THUNDER WERE CARRIED BASICALLY RIGHT WITH THE FRONTAL PASSAGE. WHILE THUNDER DOES NOT SEEM PARTICULARLY LIKELY...MODEL TIME HEIGHT SECTIONS DO INDICATE NEGATIVE THETA-E LAPSE RATES THROUGH THE DEEPLY SATURATED LAYER IN THE 5-10 KFT LAYER...WHICH IS ALL WARMER THAN 0C. SHALLOW CONVECTION WITH LOW CENTROID ECHOES AND DECENT INSTABILITY IN THE STRONGLY SATURATED LAYER COUPLED WITH PWATS UP TOWARD 1.7 INCHES SHOULD ALLOW FOR A PERIOD OF FAIRLY HEAVY RAINFALL ALONG THE FRONT. AS SUCH...QPF VALUES COULD PUSH AN INCH ACROSS THE AREA DUE TO A BIT SLOWER FRONTAL PROGRESSION. THE FRONT EXITS TO THE EAST SATURDAY NIGHT. MUCH COLDER AIR FLOODS INTO THE REGION AS CONSENSUS 850 MB TEMPERATURES FALL TOWARD +2 TO +4C. SOME STRATOCUMULUS GENERATION IS LIKELY OFF LAKE ERIE IN NORTHWESTERLY FLOW THROUGH SUNDAY...WHICH SHOULD HOLD TEMPERATURES BACK QUITE A BIT BELOW NORMAL. FRIES && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... STRONG SHORTWAVE TROUGH WILL CROSS THE AREA LATE SAT/SAT NIGHT WITH THE CAA. COULD SEE SOME ADDITIONAL SHOWERS DEVELOP WITH THIS FEATURE. STRONG SURFACE HIGH WILL MOVE THROUGH THE GREAT LAKES FOR THE REMAINDER OF THE LONG TERM. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... CLOUDS HAVE BEEN SLOW TO LIFT TODAY...BUT THINK THAT ALL LOCATIONS SHOULD EVENTUALLY REACH VFR BY SUNSET. MODELS ARE INDICATING THAT WITH MOIST LOW LEVELS...ANOTHER ROUND OF LOW MVFR/IFR CIGS ARE POSSIBLE OVERNIGHT INTO FRIDAY MORNING. CONSIDERING MODEL GUIDANCE PICKED UP ON THIS LAST NIGHT...WILL TRUST THE GUIDANCE A BIT MORE WITH THE LOW CIG FORECAST TONIGHT. WITH WINDS A BIT STRONGER FRIDAY MORNING COMPARED TO THIS MORNING...THINK CLOUDS WILL SCATTER OUT BY MID MORNING...WITH GENERALLY HIGH CLOUDS AHEAD OF THE ADVANCING COLD FRONT. WIDESPREAD PRECIPITATION IS EXPECTED TO STAY WEST OF ZZV BY 18Z AND PIT BY 00Z SATURDAY. .OUTLOOK.../FRIDAY NIGHT THROUGH TUESDAY/... WIDESPREAD RESTRICTIONS CAN BE EXPECTED FRI NGT THROUGH SAT NGT AS RAIN DVLPS WITH A CROSSING CDFNT. HIGH PRESSURE SHOULD THEN KEEP CONDITIONS VFR SUNDAY THROUGH TUESDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
409 PM EDT THU SEP 19 2013 .SYNOPSIS... ISSUED AT 407 PM EDT THU SEP 19 2013 IT WILL BE WARM AND HUMID ACROSS NORTHERN MICHIGAN THROUGH FRIDAY...AHEAD OF A STRONG COLD FRONT PUSHING ACROSS THE WESTERN LAKES. THIS BOUNDARY WILL GENERATE SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS THROUGH FRIDAY...BEFORE SEASONAL CONDITIONS AND SOME LAKE INDUCED RAINS RETURN TO NORTHERN MICHIGAN TO START THE WEEKEND. HIGH PRESSURE WILL SETTLE INTO THE REGION SUNDAY AND MONDAY. THIS PATTERN WILL GENERATE AN EXTENDED STRETCH OF DRY AND COMFORTABLE WEATHER ACROSS THE GREAT LAKES FOR THE FIRST OFFICIAL WEEK OF FALL. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 407 PM EDT THU SEP 19 2013 WARM...AND AN APPRECIABLY MUGGY AIRMASS...HAS OVERSPREAD THE NORTH WOODS THIS AFTERNOON. DESPITE THIS...LOSS OF ANY DYNAMICS HAS LED TO A DRY LATE MORNING AND EARLY AFTERNOON...WITH FOCUS FOR RAINS SHIFTING WELL TO OUR SOUTH AND WEST. FORMER TIED TO REMNANT COLD POOL AND LOW LEVEL JET DYNAMICS...WITH THE LATTER FOCUSED ALONG AND AHEAD OF STRONG SHORTWAVE TROUGH AND ATTENDANT COLD FRONT SUPPORT. THIS UPSTREAM SYSTEM WILL BE THE IMPETUS FOR ADDITIONAL SHOWERS AND STORMS HEADING INTO TONIGHT AND FRIDAY. FORECAST CHALLENGES CENTER ON THESE RAIN POSSIBILITIES. TOUGH CALL FOR THE REMAINDER OF THIS AFTERNOON INTO EARLY THIS EVENING. APPEARS FOCUS FOR ANY RAINS WILL BE CENTERED ON LOW LEVEL CONVERGENCE AXES AND DEVELOPMENT OF SURFACE INSTABILITY. NOTED CONVERGENCE AXIS DRIFTING SLOWLY NORTH ACROSS THE HIGHLANDS AS OF THIS WRITING...WELL EVIDENT ON LOCAL RADAR IMAGERY. PER SPS SURFACE ANALYSIS...BULLSEYE OF 1.5K TO 2.0K ML CAPE HAS DEVELOPED OVER INTERIOR NORTHERN LOWER MICHIGAN. STILL EVIDENCE OF SOME WEAKISH CINH TO OVERCOME. REALLY NOT SURE HOW THIS WILL ALL PLAY OUT...BUT FEEL ABOVE DEFINITELY WORTHY OF KEEPING SOME SHOWER AND STORM MENTION HEADING INTO EARLY THIS EVENING. FOR WHAT IT`S WORTH...LATEST RAP SHOWS GOOD STORM DEVELOPMENT HEADING INTO THIS PERIOD...FOCUSED ACROSS THE INTERIOR HIGHLANDS. RELATIVELY HIGH PWATS SUPPORT LOCALLY HEAVY RAINS IF/WHERE CONVECTION DEVELOPS. FOCUS WILL SHIFT TO LOW LEVEL JET DYNAMICS AND APPROACH OF COLD FRONT FOR SHOWER AND STORM POTENTIAL HEADING INTO TONIGHT. RECENT TRENDS AND PATTERN RECOGNITION SUPPORT BEST FORCED LOW LEVEL MASS CONVERGENCE FOCUSED ALONG THE LAKE MICHIGAN CORRIDOR OF NORTHWEST LOWER AND EASTERN UPPER MICHIGAN AFTER 05Z. MOISTURE REMAINS GREAT...AND SIMPLE MAGNITUDE OF CONVERGENCE SHOULD BE ENOUGH TO DRIVE ADDITIONAL ACTIVITY. WILL FOCUS BEST POTENTIAL IN THESE AREAS...TAPERING TO JUST CHANCY WORDING ACROSS NORTHEAST LOWER MICHIGAN. ELEVATED NATURE OF STORMS SHOULD PRECLUDE MUCH SEVERE POTENTIAL. ONCE AGAIN... HOWEVER...GOOD MOISTURE PROFILES SUPPORT LOCALLY HEAVY RAIN CONCERNS. SURFACE FRONT LOOKS TO REMAIN AGGRESSIVE HEADING INTO FRIDAY...WITH LATEST GFS/ECMWF TRENDS DRIVING THE FRONT INTO LAKE HURON THROUGH EARLY AFTERNOON. PRE-FRONTAL SHOWERS AND STORMS SHOULD CONTINUE...WITH STRONG UPPER JET SUPPORT AND FGEN DYNAMICS DRIVING POST-FRONTAL RAINS IMMEDIATELY BEHIND THE SURFACE PORTION OF THE FRONT. INHERITED GRIDS WELL TRENDED THIS DIRECTION WITH NO SIGNIFICANT CHANGES NEEDED. DESPITE DECENT KINEMATICS...PLENTY OF CLOUD COVER AND FASTER TIMING OF FRONT LOOKS TO KEEP SURFACE BASED INSTABILITY IN CHECK...ONCE AGAIN PRECLUDING MUCH SEVERE WEATHER POTENTIAL. LATEST SPC GRAPHICS CONCUR...KEEPING SLIGHT CHANCE WORDING JUST TO OUR SOUTHEAST. && .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 407 PM EDT THU SEP 19 2013 OVERVIEW AND TRENDS: SUBSTANTIAL LONG WAVE TROUGHING IN PLACE THIS MORNING FROM THE GULF OF ALASKA DOWN ALONG THE WEST COAST...WITH DOWNSTREAM RIDGING/WARM AIR ACROSS THE CENTRAL CONUS INTO THE GREAT LAKES...AND TROUGHING FROM GREENLAND DOWN THROUGH EASTERN CANADA. LONG WAVE RIDGING IS STILL SLATED TO SLOWLY ADVANCE INTO THE EASTERN CONUS THROUGH THE WEEKEND...WHILE LARGER SCALE FLOW FLATTENS AND CONTRACTS TOWARD THE POLE AS WE GO THROUGH NEXT WEEK. SO...NO LONG LASTING TRANSITION TOWARD COOL FALL WEATHER JUST YET. ON THE SMALLER SCALE...A COUPLE OF STRONGER SHORT WAVES EMBEDDED WITHIN THE LARGER SCALE FLOW...ONE PUSHING INTO THE NRN PLAINS THAT WILL IMPACT US OVER THE NEXT FEW DAYS...AND ANOTHER STRONG WAVE JUST OFF THE PACIFIC NW COAST THAT WILL PUSH INTO THE PAC NW LATER THIS WEEKEND. CLOSER TO HOME...LOW PRESSURE STRETCHES FROM SOUTH-CENTRAL CANADA INTO THE NRN PLAINS...AHEAD OF THE AFOREMENTIONED SHORT WAVE. ASSOCIATED WARM FRONT STRETCHES DOWN THROUGH THE MIDWEST AND TRAILING COLD FRONT FROM MINNESOTA INTO THE CENTRAL PLAINS. HAVE DEALT WITH A COUPLE OF ROUNDS OF SHOWERS AND STORMS WORKING THROUGH THE REGION ALONG ADVANCING LOW LEVEL MOISTURE AXIS PUSHING INTO THE REGION NORTH OF THE WARM FRONT. LATE FRIDAY AFTERNOON THROUGH SATURDAY...SHORT WAVE/THERMAL TROUGH AXIS ADVANCES INTO THE GREAT LAKES OVERNIGHT THROUGH SATURDAY MORNING. FROPA TIMING AMONG MODEL SOLUTIONS STILL IN GOOD AGREEMENT...KICKING THE FRONT EASTWARD INTO LAKE HURON BY EARLY FRIDAY EVENING. CONSENSUS AMONG MODEL QPF ALSO SUGGESTS MOST...IF NOT ALL...SYNOPTIC PRECIP WILL END BY EARLY EVENING...SAVE FOR JUST A SMALL SLIVER OF THE E/SE COUNTIES. HOWEVER...GIVEN THE STRONG S-N ORIENTED UPPER JET CORE ALONG THE BASE OF THE INCOMING TROUGH THAT SLIDES ACROSS THE CWA RIGHT BEHIND THE FRONT...AM STILL CONCERNED THAT POST FRONTAL/JET FORCED RAINFALL LINGERS JUST A BIT LONGER INTO THE EARLY TO MID EVENING HOURS THAN MODEL QPF SUGGESTS. WITH THAT IN MIND...HAVE SLOWED PRECIP ENDING JUST A BIT LATE FRIDAY AFTERNOON AND EARLY EVENING. PROBABLY THE PATH OF LEAST REGRET AT THIS POINT GIVEN ALL THE FRIDAY EVENING ACTIVITIES. REGARDLESS...LOW LEVEL COOL/MOIST AIR OVERSPREADING THE REGION FRIDAY EVENING (AND SOME SEMBLANCE OF A WEAK LOW LEVEL TROUGH) MAY LEAD TO STRATUS AND PERHAPS SOME PATCHY DRIZZLE FRIDAY EVENING. THEN...SUBSIDENCE AND STRONG COLD ADVECTION CONTINUE THROUGH THE REST OF FRIDAY NIGHT AND THROUGH THE DAY SATURDAY WITH H8 TEMPS DIPPING TO A FEW DEGREES ABOVE 0C BY SATURDAY MORNING...AND DOWN AROUND 0C DURING THE DAY SATURDAY. PLENTY ENOUGH COOL AIR/LAKE INSTABILITY AND SYNOPTIC MOISTURE ALONG THE BACKSIDE OF THE DEPARTING LOW FOR LAKE EFFECT/INDUCED RAIN SHOWERS OVERNIGHT FRIDAY NIGHT THROUGH A GOOD PART OF SATURDAY. SO ANOTHER COOL-ISH SATURDAY LOOKS ON TAP WITH MAINLY CLOUDY SKIES...SCATTERED RAIN SHOWERS AND SOME GUSTIER NW WINDS. SATURDAY NIGHT THROUGH SUNDAY NIGHT...IMPROVEMENT SATURDAY NIGHT AND ESPECIALLY SUNDAY AS LARGE EXPANSE OF HIGH PRESSURE BUILDS OVER THE REGION AND SUBSTANTIALLY DRIER AIR BUILDS OVERHEAD. COOLEST NIGHTS OF FORECAST WILL OCCUR BOTH SATURDAY NIGHT AND SUNDAY NIGHT AS CLEARING SKIES/WEAKENING WINDS SET THE STAGE FOR GOOD RADIATIONAL COOLING. A GOOD DEAL OF SUNSHINE FOR SUNDAY WITH TEMPERATURES REBOUNDING JUST A BIT TO THE MIDDLE 50S TO LOWER 60S. MONDAY THROUGH THURSDAY...LARGE EXPANSE OF HIGH PRESSURE WILL REMAIN THE DOMINANT WEATHER FEATURE ACROSS THE GREAT LAKES AND ACROSS EASTERN CANADA THROUGH MUCH OF NEXT WEEK...WITH FAIR WEATHER ANTICIPATED TO KICK OFF THE FIRST OFFICIAL WEEK OF FALL. GRADUAL WARMING TREND THROUGH MIDWEEK AS TEMPERATURES REBOUND BACK TO AROUND NORMAL READINGS FOR MID-LATE SEPTEMBER. GFS SOLUTION HAS ENOUGH WARM/MOIST ADVECTION INTO THE UPPER MIDWEST/WESTERN GREAT LAKES TO CONSIDER SOME CHANCES FOR SHOWERS BY THURSDAY. ECMWF IS NOWHERE CLOSE WITH HIGH PRESSURE REMAINING DOMINANT. WILL FOLLOW THE DRY ECMWF FOR NOW. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 135 PM EDT THU SEP 19 2013 SHOWERS AND STORMS WILL LIKELY BE ON THE INCREASE ONCE AGAIN HEADING THROUGH TONIGHT AND INTO FRIDAY AS A STRONG COLD FRONT MOVES THROUGH THE REGION. WILL INTRODUCE MVFR CONDITIONS WITH PASSAGE OF BETTER SHOWERS AND MOST AGGRESSIVE DYNAMICS. SOME CONCERN FOR IFR CIGS DEVELOPING IN AND JUST BEHIND THE PRIMARY RAIN SHIELD HEADING INTO FRIDAY MORNING. CONFIDENCE JUST NOT THERE TO INCLUDE AT THIS TIME. LOW LEVEL JET WILL LEAD TO WIND SHEAR OVER THE WESTERN TAF SITES TONIGHT. && .MARINE... ISSUED AT 407 PM EDT THU SEP 19 2013 GUSTY SOUTH WINDS WILL CONTINUE TONIGHT...ESPECIALLY ACROSS LAKE MICHIGAN...AS A STRONG COLD FRONT APPROACHES THE NORTHERN LAKES. CURRENT TRENDS SUPPORT CONDITIONS REMAINING JUST BELOW SCA CRITERIA. SHOWERS AND STORMS EXPECTED TO REDEVELOP THIS EVENING AND OVERNIGHT...POSSIBLY LEADING TO LOCAL ENHANCEMENT OF WINDS. WINDS VEER MORE WESTERLY BEHIND THE PASSING FRONT FRIDAY...REMAINING GUSTY AT TIMES. WINDS INCREASE AND BECOME NORTHWEST FRIDAY NIGHT AND SATURDAY. SCA/S WILL LIKELY BE NEEDED DURING THIS PERIOD. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ SYNOPSIS...KB SHORT TERM...MB LONG TERM...BA AVIATION...MB MARINE...MB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
355 PM CDT THU SEP 19 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 237 PM CDT THU SEP 19 2013 AS OF 2 PM...THE FRONT WAS STILL SLOWLY MOVING ACROSS THE EASTERN HALF OF MINNESOTA...BUT IT HAD NOT PASSED THROUGH THE TWIN CITIES METRO. EVEN WITH THE THE THUNDERSTORM ACTIVITY DIMINISHING IN WESTERN WI...THERE IS STILL A NICE POOL OF INSTABILITY IN WI AND EASTERN IA. THE STEEPEST CAPE GRADIENT EXTENDS FROM ROUGHLY EAU CLAIRE...TO ALBERT LEA. THIS SAME AREA HAS SEEN MOSTLY CLEAR SKIES SO FAR TODAY...BUT TOWERING CU HAS FILLED IN ACROSS MUCH OF THIS AREA WITH SCATTERED SHOWERS. IF THERE IS TO BE CONVECTIVE REDEVELOP IN THE MPX FORECAST AREA...THEN THIS IS THE SPOT TO KEEP AN EYE ON. THERE IS A NICE SHORTWAVE IN EASTERN NE THAT SHOULD CONTINUE TO DRIVE STORMS ACROSS IA. FARTHER NORTH THERE ARE FAR MORE QUESTIONS AND WE THINK ACTIVITY WILL LARGELY REMAIN EAST AND SOUTH OF HERE. THAT BEING SAID...THE 19.17Z HRRR HAS ANOTHER LINE OF STORMS GOING RIGHT ALONG THE AFOREMENTIONED CAPE GRADIENT LATE THIS AFTERNOON...AROUND 21Z FOR EAU CLAIRE. OTHERWISE...LOOK FOR SOME NICE COLD ADVECTION TONIGHT AND TOMORROW WITH A DRIER AND BREEZY NORTHWEST FLOW. THERE IS ACTUALLY A SECONDARY COLD FRONT BACK ACROSS THE DAKOTAS ASSOCIATED WITH THAT STRATO CU DECK AND TEMPS IN THE UPPER 40S AND LOWER 50S. THAT IS ON TAP FOR TOMORROW. THE AIR WILL MODIFY...BUT WOULD NOT BE SURPRISED IF SOME SITES IN CENTRAL MN STRUGGLE TO GET OUT OF THE 50S. WE LOWERED HIGHS TOMORROW A BIT...BUT PROBABLY COULD HAVE GONE A COUPLE DEGREES MORE. IT WILL BE A VERY FALL LIKE DAY TOMORROW. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 355 PM CDT THU SEP 19 2013 LOTS OF DISCREPANCIES EXIST IN THE LONG RANGE WITH RESPECT TO TIMING OF INDIVIDUAL WAVES...BUT MODELS DO AGREE ON THE GENERAL PROGRESSION OF THE LARGE SCALE UPPER AIR PATTERN. THE WEEKEND WILL START WITH A RIDGE MOVING ACROSS THE NATIONS MID SECTION...BUT BY MONDAY...AN ANOMALOUSLY STRONG UPPER RIDGE WILL BECOME CENTERED OVER THE THE SE CONUS...WITH A DEEP TROUGH CARVING OUT ACROSS WRN NOAM. DURING THE WEEK...THIS WRN TROUGH WILL SLOWLY DRIFT TOWARD THE CENTRAL CONUS...APPROACHING THE UPPER MS VALLEY TOWARD THE END OF NEXT WEEK. SATURDAY STILL LOOKS TO START OUT IN THE UPPER 30S TO MID 40S...BUT DID NUDGE LOWS A COUPLE OF DEGREES UP...AS THE RIDGE AXIS DOES NOT LOOK TO COME INTO WRN MN UNTIL CLOSER TO DAY BREAK...KEEPING WINDS UP ENOUGH TO KEEP THE ATMO FROM COMPLETELY DECOUPLING. OTHERWISE...ONLY THING REMOTELY SIGNIFICANT ABOUT THE WEATHER THIS WEEKEND WILL BE THE BREEZY CONDITIONS DEVELOPING SUNDAY AS GRADIENT TIGHTENS SIGNIFICANTLY ACROSS MN IN RESPONSE TO A 1020 MB HIGH OVER THE GREAT LAKES AND A 995 MB LOW OVER THE WRN DAKOTAS. 1000-850 WINDS OFF THE NAM INCREASE TO OVER 30 KTS BY THE AFTERNOON IN WRN MN...SO SHOULD TURN INTO A FAIRLY BREEZY DAY IN OUR TYPICALLY WINDY AREAS. TIMING DETAILS QUICKLY SHOW UP WITH THE WAVE DUE TO MOVE THROUGH ON MONDAY AS MODELS STRUGGLE TO PIN DOWN HOW THE RIDGING OVER THE SOUTHEAST WILL IMPACT THE SPEED OF WAVES BACK THIS DIRECTION. THE GEM/GFS CONTINUE TO BRING A POTENT NEGATIVELY TILTED THROUGH ACROSS THE NRN PLAINS MONDAY...WITH A BAND OF SHRA/TSRA COMING ALONG WITH AS WELL. THE 19.12 ECMWF SLOWED DOWN CONSIDERABLY WITH THIS FEATURE...BRINGING IT THROUGH ABOUT 12 HRS LATER...WITH PRECIP COMING THROUGH MONDAY NIGHT AS A RESULT. GIVEN TIMING DIFFERENCES...CONTINUED WITH CHANCES POPS MON/MON NIGHT...BUT AT SOME POINT...GIVEN THE DYNAMICS ASSOCIATED WITH THE NEGATIVELY TITLED WAVE...WE SHOULD BE HEADING FOR A HIGH POP/LOW QPF TYPE SCENARIO ONCE BETTER TIMING CAN BE NAILED DOWN. GIVEN THE RIDGING TO THE SE...ITS USUALLY A SAFER BET TO GO THE SLOWER ROUTE. THIS RIDGE TO THE SOUTHEAST WILL BE A MAJOR PLAYER FOR THE WEATHER HERE THROUGH THE REST OF THE WEEK...AS IT WILL ACT TO DEFLECT MUCH OF THE SHORTWAVE ENERGY TO THE NW OF THE MPX AREA. HAVE SEEN MODELS RESPOND TO THIS...WITH EACH RUN GRADUALLY SLOWING DOWN WHEN THE NEXT SYSTEM WILL IMPACT THE AREA. THE GFS WANTS TO BRING A POTENT FRONT/LOW THROUGH WED NIGHT/THU...WHILE THE ECMWF HOLDS OFF UNTIL FRIDAY. MUCH LIKE WAS STATED IN THE PREVIOUS PARAGRAPH...GIVEN THE STRENGTH OF THE RIDGING TO THE SE...THE SLOWER PROGRESSION WILL LIKELY BE THE WAY THINGS GO...BUT GIVEN THE BLENDING PROCEDURE USED...PRECIP CHANCES RETURN WEDNESDAY. THOUGH THERE IS UNCERTAINTY ABOUT PRECIP...WHAT IS MORE CERTAIN IS THAT SW FLOW RESULTING FROM THE TROUGH WEST/RIDGE EAST WILL BRING WITH IT TEMPERATURES WELL ABOVE NORMAL...WITH HIGHS IN THE 80S LOOKING POSSIBLE BY THE MIDDLE OF NEXT WEEK...WHICH THANKS TO OUR RAPIDLY FALLING AVERAGE HIGHS WOULD BE CLOSE 20 DEGREES ABOVE NORMAL. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1240 PM CDT THU SEP 19 2013 IMMEDIATE CONCERN THIS AFTERNOON ACROSS THE AREA IS THE DEPARTING THUNDER...BRIEF POST FRONTAL LOW CIGS...AND RAPIDLY VARYING/CHANGING WIND DIRECTION. ALL MN TAF SITES ARE DONE WITH THE THUNDER AT THIS POINT...BUT WESTERN WI WILL SEE ADDITIONAL THUNDER FOR THE NEXT HOUR OR TWO. A NARROW AREA OF IFR CIGS BEHIND THE FRONT HAS DEVELOPED AND WILL TRANSLATE EAST AS IT SLOWLY DISSIPATES THIS AFTERNOON. THIS WILL NEED TO BE MONITORED TO SEE HOW LONG IT HOLDS TOGETHER. WINDS TURN NW BY THIS EVE ACROSS THE ENTIRE AREA...AND VFR CONDITIONS ARE EXPECTED BEHIND THE POST FRONTAL STRATUS...UNTIL THE EARLY MORNING HOURS. AT THAT TIME...A SHIELD OF LOW STRATUS WILL ADVECT IN FROM THE NORTHWEST...WITH THE ENTIRE AREA SEEING MVFR CIGS...WITH THE POSSIBILITY OF IFR CEILINGS BEFORE SUNRISE. CIGS WILL LIFT TO VFR BY LATE MORNING/EARLY AFTERNOON. WINDS TOMORROW WILL BE GUSTY FROM THE NORTHWEST. KMSP...VFR CONDITIONS SHOULD PREVAIL UNTIL THE OVERNIGHT HOURS WHEN THE LOW STRATUS APPROACHES NEAR SUNRISE. ADVERTISING MVFR CIGS 10-16Z...BUT BEWARE OF THE POTENTIAL FOR CEILINGS CLOSER TO 1K FT FROM AROUND 10-13Z. WINDS WILL BE NW BY TONIGHT AND REMAIN THAT WAY THROUGH THE TAF PERIOD. MVFR CIGS LIFT DUE TO MIXING TO VFR BY LATE MORNING. /OUTLOOK FOR KMSP/ && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...CLF LONG TERM...MPG AVIATION...SPD
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
238 PM CDT THU SEP 19 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 237 PM CDT THU SEP 19 2013 AS OF 2 PM...THE FRONT WAS STILL SLOWLY MOVING ACROSS THE EASTERN HALF OF MINNESOTA...BUT IT HAD NOT PASSED THROUGH THE TWIN CITIES METRO. EVEN WITH THE THE THUNDERSTORM ACTIVITY DIMINISHING IN WESTERN WI...THERE IS STILL A NICE POOL OF INSTABILITY IN WI AND EASTERN IA. THE STEEPEST CAPE GRADIENT EXTENDS FROM ROUGHLY EAU CLAIRE...TO ALBERT LEA. THIS SAME AREA HAS SEEN MOSTLY CLEAR SKIES SO FAR TODAY...BUT TOWERING CU HAS FILLED IN ACROSS MUCH OF THIS AREA WITH SCATTERED SHOWERS. IF THERE IS TO BE CONVECTIVE REDEVELOP IN THE MPX FORECAST AREA...THEN THIS IS THE SPOT TO KEEP AN EYE ON. THERE IS A NICE SHORTWAVE IN EASTERN NE THAT SHOULD CONTINUE TO DRIVE STORMS ACROSS IA. FARTHER NORTH THERE ARE FAR MORE QUESTIONS AND WE THINK ACTIVITY WILL LARGELY REMAIN EAST AND SOUTH OF HERE. THAT BEING SAID...THE 19.17Z HRRR HAS ANOTHER LINE OF STORMS GOING RIGHT ALONG THE AFOREMENTIONED CAPE GRADIENT LATE THIS AFTERNOON...AROUND 21Z FOR EAU CLAIRE. OTHERWISE...LOOK FOR SOME NICE COLD ADVECTION TONIGHT AND TOMORROW WITH A DRIER AND BREEZY NORTHWEST FLOW. THERE IS ACTUALLY A SECONDARY COLD FRONT BACK ACROSS THE DAKOTAS ASSOCIATED WITH THAT STRATO CU DECK AND TEMPS IN THE UPPER 40S AND LOWER 50S. THAT IS ON TAP FOR TOMORROW. THE AIR WILL MODIFY...BUT WOULD NOT BE SURPRISED IF SOME SITES IN CENTRAL MN STRUGGLE TO GET OUT OF THE 50S. WE LOWERED HIGHS TOMORROW A BIT...BUT PROBABLY COULD HAVE GONE A COUPLE DEGREES MORE. IT WILL BE A VERY FALL LIKE DAY TOMORROW. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 312 AM CDT THU SEP 19 2013 STRONG CAA IN THE WAKE OF THE COLD FRONT AND RESULTANT STEEP LOW LEVEL LAPSE RATES WILL PROMOTE GUSTY WINDS AND A DEVELOPMENT OF STRATOCU BEGINNING LATE TONIGHT TO THE NORTH AND WEST...PUSHING OVERHEAD FRIDAY. MODEST AMOUNTS OF INSTABILITY THROUGH THE CLOUD- BEARING LAYER MAY ALSO BRING A FEW SPRINKLES TO THE REGION... PARTICULARLY NORTH OF THE MINNESOTA RIVER. LIGHT QPF ON THE NAM/GFS/ECMWF ALSO HINT TOWARD THIS. THUS...INCREASED CLOUDS AND WINDS...AND DECREASED TEMPERATURES FRIDAY FROM THE LAST FORECAST PACKAGE. THE HIGH WILL PUSH ACROSS WESTERN MINNESOTA FRIDAY NIGHT. FORECAST SOUNDINGS REMAIN QUITE MIXED...BUT AM A BIT SKEPTICAL OF THIS WITH THE SURFACE HIGH SO NEARBY. CLOUDS WILL QUICKLY DISSIPATE FRIDAY EVENING AS CYCLONIC FLOW PUSHES OUT...SETTING THE STAGE FOR A COLD NIGHT OVER THE AREA WITH LOWS IN THE MID 30S TO LOWER 40S. UPPER RIDGING QUICKLY BUILDS BACK OVER THE PLAINS DURING THE WEEKEND. A FAIRLY IMPRESSIVE TEMPERATURE GRADIENT IS POSSIBLE ON EITHER SIDE OF THE SURFACE RIDGE AXIS ACROSS THE CWA SATURDAY AFTERNOON. A SOUTHEASTERLY SURFACE FLOW WILL ENVELOP THE ENTIRE AREA FROM SUNDAY INTO EARLY NEXT WEEK AS A SOUTHWEST FLOW IN THE UPPER ATMOSPHERE STEERS WEAKENING SYSTEMS TO THE NORTH. ONE SUCH SYSTEM WILL LIMP THROUGH MONDAY/MONDAY NIGHT. WITH RIDGING BUILDING IN IMMEDIATELY IN THE WAKE OF THE SYSTEM...A DE-AMPLIFICATION OF SAID SYSTEM WILL TAKE PLACE AND LITTLE OR NO FORCING WILL ACCOMPANY WHAT IS LEFT OF THE FRONT. THUS...MAINTAINED ONLY LOW POPS. WINDS WILL VEER MORE SOUTHERLY MIDWEEK WITH WARMER AND MORE HUMID AIR RETURNING. MODELS ARE INCONSISTENT WITH THE POSITIONING OF A SW-NW ORIENTED SURFACE BOUNDARY WITH THE EC FURTHER NORTH THAN THE GFS. GFS SOLUTION WOULD BRING HIGHER POPS. EITHER WAY...TEMPERATURES SHOULD BE 10-15 DEGREES ABOVE AVERAGE DURING THIS PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1240 PM CDT THU SEP 19 2013 IMMEADITE CONCERN THIS AFTERNOOON ACROSS THE AREA IS THE DEPARTING THUNDER...BRIEF POST FRONTAL LOW CIGS...AND RAPIDLY VARYING/CHANGING WIND DIRECTION. ALL MN TAF SITES ARE DONE WITH THE THUNDER AT THIS POINT...BUT WESTERN WI WILL SEE ADDITIONAL THUNDER FOR THE NEXT HOUR OR TWO. A NARROW AREA OF IFR CIGS BEHIND THE FRONT HAS DEVELOPED AND WILL TRANSLATE EAST AS IT SLOWLY DISSIPATES THIS AFTERNOON. THIS WILL NEED TO BE MONITIORED TO SEE HOW LONG IT HOLDS TOGETHER. WINDS TURN NW BY THIS EVE ACROSS THE ENTIRE AREA...AND VFR CONDITIONS ARE EXPECTED BEHIND THE POST FRONTAL STRATUS...UNTIL THE EARLY MORNING HOURS. AT THAT TIME...A SHIELD OF LOW STRATUS WILL ADVECT IN FROM THE NORTHWEST...WITH THE ENTIRE AREA SEEING MVFR CIGS...WITH THE POSSIBILITY OF IFR CEILINGS BEFORE SUNRISE. CIGS WILL LIFT TO VFR BY LATE MORNING/EARLY AFTERNOON. WINDS TOMORROW WILL BE GUSTY FROM THE NORTHWEST. KMSP...VFR CONDITIONS SHOULD PREVAIL UNTIL THE OVERNIGHT HOURS WHEN THE LOW STRATUS APPROACHES NEAR SUNRISE. ADVERTISING MVFR CIGS 10-16Z...BUT BEWARE OF THE POTENTIAL FOR CEILINGS CLOSER TO 1K FT FROM AROUND 10-13Z. WINDS WILL BE NW BY TONIGHT AND REMAIN THAT WAY THROUGH THE TAF PERIOD. MVFR CIGS LIFT DUE TO MIXING TO VFR BY LATE MORNING. /OUTLOOK FOR KMSP/ && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...CLF LONG TERM...BORGHOFF AVIATION...SPD
AREA FORECAST DISCUSSION
NWS BILLINGS MT
238 PM MDT THU SEP 19 2013 .SHORT TERM...VALID FOR FRI AND SAT... UPPER TROF CONTINUES TO SHIFT EAST AND WE ARE BEGINNING TO SEE HEIGHT RISES INTO CENTRAL MT. SOME LIGHT SHOWERS REMAIN EAST OF MILES CITY...ASSOCIATED WITH WEAK SHORTWAVE EMBEDDED IN THE NW FLOW ALOFT...BUT THIS ACTIVITY IS WEAKENING AND WILL BE DONE BEFORE 00Z. ISSUES FOR TONIGHT INCLUDE FOG AND FROST POTENTIAL. PLENTY OF CLOUD COVER CURRENTLY EXISTS IN OUR EAST BUT THIS WILL BE DISSIPATING INTO THE EVENING. CURRENT DEWPTS ARE NOTEWORTHY...IN THE UPPER 30S TO AROUND 40...AND WILL NOT SEE ANY SIGNIFICANT LOW LEVEL DRYING IN OUR EAST BEFORE SUNSET. WITH THIS IN MIND...AND AS SFC RIDGE BUILDS TO THE SOUTHEAST ALLOWING FOR THE NWLY GRADIENT TO RELAX...BELIEVE SOME FOG OR STRATUS DEVELOPMENT IS POSSIBLE IN OUR EAST. MIGHT LEAN TOWARD PATCHY VALLEY FOG HERE AS RAP SHOWS A DECENT NW WIND AT 850MB THRU 12Z. WITHOUT ANY STRATUS BELIEVE SOME AREAS IN OUR FAR EAST WILL SEE SOME FROST WITH TEMPS INTO THE MID 30S TONIGHT. IN OUR WEST...CLEAR SKIES A CERTAINTY WITH ONLY WEAK DOWNSLOPE GRADIENTS DEVELOPING AFTER MIDNIGHT. SO BELIEVE NOTORIOUSLY COLDER SPOTS SUCH AS HARLOWTON...LIVINGSTON AND SHERIDAN WILL SEE SOME FROST TONIGHT. DEWPTS ARE PROBABLY TOO HIGH TO SUPPORT A REAL FREEZE THOUGH. GENERALLY SPEAKING HAVE LOWERED TEMPS FOR TONIGHT A BIT MORE...AND THIS IS CONSISTENT WITH THE SLOWER PROGRESSING UPPER TROF AND COOLING TREND IN ALL GUIDANCE. FOR BILLINGS...COULD SEE MID OR UPPER 30S FOR LOWS ALONG THE YELLOWSTONE VALLEY...BUT RIDGES SHOULD NOT FALL BELOW THE LOW 40S. DRY WX WITH A WARMING TREND IN STORE FOR FRI/SAT AS STRONG RIDGE ALOFT BUILDS OVER THE REGION. EXPECT TEMPS TO CLIMB BACK INTO THE 70S TOMORROW AND 80S ON SAT...WITH GOOD CONFIDENCE IN A STRONG WARM UP SUPPORTED BY DRY AIRMASS SETTLING IN AND WHAT WILL BE DEW PTS IN THE 20S AND 30S. DEEPER MIXING OF INCREASED SW WINDS ALOFT WILL RESULT IN GUSTY WINDS FOR OUR WESTERN FOOTHILLS INCLUDING LIVINGSTON ON SAT...WHICH WILL COINCIDE WITH AFTN RHS IN THE LOW TEENS. THESE CONDITIONS WILL BE HIGHLIGHTED IN THE FIRE WEATHER FORECAST. NEXT PACIFIC TROF...THOUGH WEAKENING AS IT COMES INLAND...WILL BEGIN TO IMPACT OUR FAR WEST LATE SAT NIGHT. HAVE SCALED BACK POPS SLIGHTLY AND PUSHED THEM WEST AFTER 06Z...BASED ON MODEL CONSENSUS FOR THIS SLOWER TIMING. WEAK COLD FRONT WILL ALLOW FOR COOLER PACIFIC AIR TO BEGIN SPREADING IN FROM THE WEST LATE SAT NITE... SETTING UP A COOLER SUNDAY. JKL .LONG TERM...VALID FOR SUN...MON...TUE...WED...THU... THE EXTENDED FORECAST LOOKS A LOT MORE LIKE FALL WITH TWO WEATHER SYSTEMS TO WATCH. THE FIRST SYSTEM WILL IMPACT THE REGION ON SUNDAY...AND WILL BRING SOME SNOW SHOWERS TO HIGH ELEVATIONS IN THE MOUNTAINS AND RAIN SHOWERS ACROSS THE REST OF THE FORECAST AREA...BRINGING TEMPERATURES BACK TO NEAR SEASONAL NORMALS. THE SECOND SYSTEM...WHICH IS MUCH MORE INTERESTING...WILL IMPACT THE REGION BY WEDNESDAY AND THURSDAY...AND WILL BRING MUCH BELOW NORMAL TEMPERATURES AND A GOOD CHANCE OF WIDESPREAD PRECIPITATION. ...SUNDAY THROUGH TUESDAY... A SPLITTING TROUGH WILL CROSS THE REGION ON SUNDAY...BRINGING AN INCREASE IN PACIFIC MOISTURE AND QG FORCING ACROSS THE FORECAST AREA. ELEVATED MOUNTAIN LOCATIONS WILL LIKELY CATCH SOME SNOW SHOWERS WITH THIS SYSTEM AS H7 TEMPS DECREASE TO AROUND 0C. WINDS WILL REMAIN MOSTLY WESTERLY AND DOWNSLOPE...WHICH WILL ACT TO LIMITE THE AMOUNT OF PRECIPITATON ACROSS THE PLAINS LOCATIONS. HOWEVER...FULLY EXPECT A COOLER AND CLOUDY DAY WITH SCATTERED RAIN SHOWERS ACROSS THE PLAINS. THE FLOW BEHIND THE WAVE FOR MONDAY AND TUESDAY WILL REMAIN NEAR ZONAL WITH THE JET OVERHEAD...KEEPING TEMPERATURES NEAR NORMAL AND A CHANCE OF SOME SHOWERS IN THE MOUNTAINS...OTHERWISE THE REMAINDER OF THE FORECAST AREA SHOULD STAY DRY. ...WEDNESDAY AND THURSDAY... GLOBAL MODELS ARE EXTREMELY CONSISTENT WITH THE WEATHER PATTERN OVER THE PACIFIC BY THIS TIME FRAME...AND ALL DEVELOP A DIGGING TROUGH DOWN THE WEST COAST BY TUESDAY INTO WEDNESDAY. THE PATTERN WILL OPEN THE DOOR TO MUCH COOLER TEMPERATURES FOR WEDNESDAY AND THURSDAY. WHILE THERE ARE MINOR DIFFERENCES IN THE EVOLUTION OF THE TROUGH...BOTH THE GFS AND ECMWF POSITION THE LOW JUST TO OUR WEST BY WEDNESDAY AFTERNOON AND SLIDE THE LOW ACROSS OUR SOUTH BY THURSDAY. THIS SOLUTION IS FAVORABLE FOR A PROLONGED UPSLOPE EVENT. THAT COMBINED WITH THE DYNAMICS OF THE LOW COULD PRODUCE A WIDESPREAD PRECIPITATION EVENT ACROSS THE AREA...AND IN PARTICULAR ALONG THE FOOTHILLS AND EAST FACING MOUNTAIN LOCATIONS. TEMPERATURES ARE COOL ENOUGH THAT SNOW IN THE MOUNTAINS WOULD BE LIKELY AND COULD GET INTO HIGH FOOTHILLS LOCATIONS. TEMPERATURES ACROSS THE PLAINS WOULD CERTAINLY BE THE COOLEST WE HAVE SEEN THIS FALL...BUT AT THIS POINT LOOK JUST WARM ENOUGH FOR MAINLY RAIN EVENT. THIS WEATHER SYSTEM WILL BE THE ONE TO WATCH AS IT BECOMES CLOSER IN TIME. CHURCH && .AVIATION... THE LOWER CLOUD DECK WILL CONTINUE TO ERODE FROM WEST TO EAST ACROSS THE AREA AS DRIER AIR WORKS IN FROM THE WEST. MVFR CEILINGS SHOULD BE LIMITED TO FAR EASTERN MONTANA...NEAR KBHK THIS AFTERNOON. OTHERWISE VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES OVERNIGHT. WINDS WILL ALSO CONTINUE TO DECREASE THROUGH THIS EVENING. CHURCH && .PRELIMINARY POINT TEMP/POPS... FRI SAT SUN MON TUE WED THU ----------------------------------------------------------- BIL 043/075 050/084 054/069 048/071 048/068 047/055 043/052 00/U 00/U 12/T 11/B 02/T 23/W 44/W LVM 034/078 042/086 047/065 042/068 043/065 043/048 038/047 00/U 00/N 22/T 11/B 12/T 23/W 44/W HDN 038/078 046/086 051/073 046/073 045/073 047/059 044/054 00/U 00/U 02/T 21/B 01/B 13/W 44/W MLS 040/075 049/084 054/075 051/075 050/075 050/063 047/057 00/U 00/U 02/T 21/U 11/B 13/W 44/W 4BQ 038/074 044/084 053/076 046/074 046/074 047/065 046/056 00/U 00/U 02/T 21/U 11/U 12/W 33/W BHK 036/070 043/080 050/077 046/073 044/075 045/064 048/057 00/U 00/U 02/T 21/U 11/U 12/W 44/W SHR 035/076 045/084 050/072 044/071 045/073 044/060 042/051 00/U 00/U 02/T 30/U 01/U 12/W 44/W && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
122 PM CDT THU SEP 19 2013 .AVIATION... 18Z TAFS FOR KOMA...KOFK...KLNK SURFACE COLD FRONT AT 18Z EXTENDED FROM SOUTH OF KOMA TO SOUTH OF KLNK WILL CONTINUE TO MOVE SLOWLY SOUTHEASTWARD THROUGH THE FORECAST PERIOD. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED AT KOMA AND KLNK THROUGH 21Z. SOME STORMS MAY BECOME SEVERE SOUTH AND EAST OF KLNK THROUGH 19/00Z. CEILINGS ARE EXPECTED TO REMAIN ABOVE MVFR RANGE IN THUNDERSTORM AREAS. JUST BEHIND THE FRONT...CEILINGS MAY DROP BRIEFLY INTO MVFR RANGE BEFORE BECOMING VFR THE REMAINDER OF THE PERIOD. SMITH && DISCUSSION... GLANCE AT REGIONAL RADAR ALREADY SHOWING LINE OF CONVECTION FIRING ALONG INTENSE SFC BAROCLINIC ZONE EXTENDING FROM ABOUT NRN MN TO NWRN KS. BNDRY IN ASSOCIATION WITH UPPER SHORTWAVE TROF MIGRATING ACROSS THE NRN PLAINS. AGEOSTROPHIC LIFT JUST AHEAD OF RELATIVELY DEEP FRONTOGENESIS BNDRY IS QUITE STOUT...PER RUC13. ALSO...STRONG UPPER LEVEL DIVG ASSOCIATE WITH RRQ OF JET MAX ALOFT CONTRIBUTING TO ENHANCEMENT OF SYNOPTIC LIFT AS WELL. SHORT TERM ISSUE IS TIMING THE FRONTAL PASSAGE/PCPN THRU THE CWA. REGIONAL RADAR WAS SHOWING AN OUTFLOW BNDRY ASSOCIATED WITH CLUSTER OF STORMS IN WRN NEB WAS QUICKLY PUSHING EAST...AND WILL PROBABLY REACH THE CWA IN THE NEXT COUPLE HOURS. AT ANY RATE...SFC WIND PROGS VIA TIME-SERIES INDICATE LEADING EDGE OF THE TRUE FRONT REACHING KOFK BY LATE MORNING...THEN EARLY AFTN AT KLNK AND KOMA...THUS APPROXIMATE TIME FRAME FOR FOR EXPECTED CONVECTION. MEANWHILE... PERSISTENT MOISTURE ADV INTO THE REGION THE LAST 24 HRS HAS CULMINATED IN A MOISTURE RICH ENVIRONMENT AS SEE BY PWS VALUES RANGING ANYWHERE FROM 160%-220% ABOVE NORM AHEAD OF THE FRONT. AT THIS POINT SUSPECT THAT PCPN INTENSITY WILL INCREASE THIS AFTN OVER SRN CWA WHERE THE RUC13 IS SHOWING PRECIP EFFICIENCY/WARM CLOUD DEPTH PEAKS. IMPROVING CONDITIONS THEN TONIGHT AS STABLE AIRMASS ENVELOPS THE REGION. IN CASE OF LINGERING PCPN ACTIVITY...WILL MAINTAIN TOKEN EVENING POPS SOUTH. EXCELLENT WEATHER ON TAP THIS WEEKEND IN RESPONSE TO UPPER RIDGE BUILDING OVER THE PLAINS. NEXT ROUND OF PCPN COMES SUNDAY NIGHT/MONDAY WHEN NEXT POTENT SHORTWAVE TROF EXITS THE ROCKIES AND SWEEPS ANOTHER COLD FRONT INTO THE CNTRL PLAINS. WITH GFS AND ECM IN AGREEMENT DECENT LLVL MOISTURE FEED PRECEDING THE FRONT...GENEROUS RAINFALL AMOUNTS WILL ONCE AGAIN BE POSSIBLE. DEE && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
327 PM CDT THU SEP 19 2013 .DISCUSSION...WATER VAPOR SATELLITE/UPPER AIR PROFILER/WSR-88D VAD WIND PROFILE TRENDS STILL PLACE AN UPPER LEVEL RIDGE AXIS OVER THE SOUTHEAST UNITED STATES THIS AFTERNOON. THIS IS RESULTING IN ACROSS THE MID SOUTH WITH ISOLATED TO SCATTERED SHOWER AND THUNDERSTORM ACTIVITY THUS FAR LIMITED TO PORTIONS OF CENTRAL/NORTH CENTRAL ARKANSAS AND SOUTH CENTRAL/SOUTHEAST MISSOURI. TEMPERATURES AS OF 3 PM CDT ARE IN THE MIDDLE TO UPPER 80S AT MOST LOCATIONS. SHOWER AND THUNDERSTORM CHANCES ASSOCIATED WITH AN APPROACHING COLD FRONT IS THE MAIN FORECAST CHALLENGE IN THIS AFTERNOON/S FORECAST. SHORT TERM MODELS INCLUDING THE 3KM HRRR INDICATE SHOWERS AND THUNDERSTORMS LOCATED OVER PORTIONS OF ARKANSAS AND SOUTHERN MISSOURI WILL WEAKEN AND DIMINISH WITH THE LOSS OF DAYTIME HEATING THIS EVENING. THERE IS A POSSIBILITY THAT SOME OF THIS ACTIVITY MAY REACH AREAS WEST OF THE MISSISSIPPI RIVER THIS EVENING AND LEFT ISOLATED SHOWERS AND THUNDERSTORMS IN THE FORECAST. HOWEVER...THINK BETTER SHOWER/THUNDERSTORM CHANCES WILL HOLD OFF UNTIL LATER TONIGHT AS THE RIDGE MOVES FURTHER EAST AND MID LEVEL HEIGHT FALLS WEAKEN SLIGHTLY. A COLD FRONT CURRENTLY LOCATED OVER THE UPPER MIDWEST AND CENTRAL PLAINS THIS AFTERNOON WILL DROP INTO THE LOWER MISSISSIPPI VALLEY ON FRIDAY. MODEST MID LEVEL HEIGHT FALLS AND INSTABILITY WILL ALLOW FOR SHOWERS AND THUNDERSTORMS TO OVERSPREAD THE MID SOUTH MAINLY ALONG AND WEST OF THE MISSISSIPPI RIVER FRIDAY MORNING AND SPREAD EAST TO THE REMAINDER OF THE FORECAST AREA FRIDAY AFTERNOON INTO FRIDAY NIGHT. NOT OVERLY IMPRESSED WITH STRONG/SEVERE THUNDERSTORM POTENTIAL AS OVERALL SHEAR...INSTABILITY...AND FORCING WILL REMAIN ON THE WEAK SIDE. LATER SHIFTS WILL MONITOR SHORT TERM TRENDS AND ADD STRONG THUNDERSTORM MENTION IN THE HAZARDOUS WEATHER OUTLOOK IF CONDITIONS BECOME MORE FAVORABLE AS THE FRONT APPROACHES. OVERALL RAINFALL AMOUNTS THROUGH FRIDAY NIGHT MAY AVERAGE AROUND ONE HALF INCH WITH LOCALIZED AMOUNTS UP TO PERHAPS 1.5-2 INCHES ALONG AND WEST OF THE MISSISSIPPI RIVER...AND LESSER AMOUNTS TOWARDS THE TENNESSEE RIVER. THE 12Z GFS HAS REMAINED ON THE QUICKER SIDE OF MODEL SOLUTIONS TODAY AND LEANED FORECAST TOWARDS THE WRF/ECMWF WHICH SUGGEST FRONTAL PASSAGE FRIDAY AFTERNOON/FRIDAY NIGHT. LINGERING SHOWERS AND THUNDERSTORMS MAY PERSIST ON SATURDAY...ESPECIALLY ACROSS NORTHEAST MISSISSIPPI AS THE FRONT SLOWS BEFORE DEPARTING THE FORECAST AREA BY SATURDAY NIGHT. COOLER AND DRIER AIR WILL FILTER IN BEHIND THE FRONT RESULTING IN A PERIOD OF MAINLY RAIN FREE WEATHER ACROSS THE MID SOUTH THROUGH AT LEAST EARLY NEXT WEEK AND TEMPERATURES AVERAGING NEAR NORMAL FOR SEPTEMBER. 12Z GFS/ECMWF INDICATE SOME MODEL RUN TO RUN CONTINUITY ISSUES WITH THE APPROACH OF AN UPPER LEVEL TROUGH OVER THE PLAINS/MIDWEST...A BUILDING RIDGE OVER THE LOWER MISSISSIPPI VALLEY AND THE POTENTIAL FOR WEAK SOUTHERLY LOW LEVEL RETURN FLOW FROM THE GULF OF MEXICO PRODUCING SHOWERS AND THUNDERSTORMS. WILL KEEP REMAINDER OF FORECAST NEXT WEEK DRY FOR NOW UNTIL MODELS COME INTO BETTER AGREEMENT. CJC && .AVIATION... 18Z TAF CYCLE VFR CONDS WILL PREVAIL THROUGHOUT THE PERIOD. A FEW SHOWERS AND THUNDERSTORMS MAY DEVELOP THIS AFTERNOON BUT COVERAGE IS NOT EXPECTED TO BE ENOUGH TO INCLUDE IN TAFS. WILL AMEND AS NECESSARY BASED ON RADAR TRENDS. WINDS WILL BE SOUTH AT 8-12 KTS...ONLY DIMINISHING SLIGHTLY OVERNIGHT IN ADVANCE OF A COLD FRONT. A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS IS EXPECTED LATE IN THE FORECAST PERIOD. WILL LIKELY ADD PREVAILING SHOWERS IN LATER UPDATES...WILL START WITH VCSH AT ALL SITES TOMORROW BETWEEN 10Z AT JBR AND 16Z AT TUP. MEM AND MKL SHOULD SEE SHOWERS AROUND 14Z. && .PRELIMINARY POINT TEMPS/POPS... MEM 72 84 67 81 / 30 80 70 40 MKL 68 84 65 78 / 20 60 70 30 JBR 70 80 61 78 / 50 90 60 10 TUP 68 87 68 81 / 10 50 90 70 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. && $$
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
130 PM CDT THU SEP 19 2013 .UPDATE...FOR 18Z TAFS. && .AVIATION... THE MID-SOUTH WILL REMAIN IN THE WARM SECTOR AS A COLD FRONT APPROACHES. THIS FRONT IS EXPECTED TO MOVE INTO MIDDLE TN LATE FRIDAY NIGHT. THROUGH THIS PERIOD...LITTLE IMPACT WILL BE FELT DESPITE MOISTURE SLOWLY INCREASING. STRATA CU ABV 3KFT TODAY WILL DISSIPATED AFTER SUNSET BUT POSSIBLY RETURN TOWARD SUNRISE CKV/BNA. SOME EARLY MORNING LIGHT FOG MAY DEVELOP CSV AS WELL. OVERALL...VFR CONDITIONS WILL DOMINATE THE PERIOD. SOUTH WIND TODAY MAY BRIEFLY GO ABV 10KNTS. && .PREV DISCUSSION... /ISSUED 851 AM CDT THU SEP 19 2013/ UPDATE... WARM FRONT WILL CONTINUE TO LIFT NORTHWARD AND AWAY FROM TN TODAY. MEANWHILE...SFC HIGH WILL ALSO CONTINUE TO MOVE EAST TOWARD THE ATLANTIC COAST. NO APPRECIABLE UPPER DYNAMICS ARE APPARENT AS THE UPPER RIDGE AXIS WILL ACTUALLY BE IN CLOSER PROXIMITY TO THE MID STATE BY LATE THIS AFTERNOON. HOWEVER...SOME WEAK BUT FAVORABLE CURVATURE AND SHEAR WILL ROTATE ACROSS PORTIONS OF THE AXIS LATER TODAY. THIS ALL TRANSLATES INTO A SLIGHT CHANCE OF SHOWERS OR TSTMS ACROSS NORTHERN AREAS. TEMPERATURES SHOULD BE A FEW DEGREES GREATER THAN YESTERDAY. THUS...UPPER 80S FOR HIGHS STILL LOOKS REASONABLE. HRRR IN LINE WITH CURRENT FCST THINKING. ONLY MOD WILL BE TO RERUN ZONES WHICH WILL AUTOMATICALLY REMOVE THE PATCHY FOG WORDING. PREV DISCUSSION... /ISSUED 614 AM CDT THU SEP 19 2013/ UPDATE...FOR AVIATION. AVIATION... 12Z TAFS...VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THIS PERIOD...THE ONLY EXCEPTION WILL BE SOME POSSIBLE EARLY MORNING MVFR FOG. SURFACE HIGH PRESSURE ALONG THE EAST COAST WILL PRODUCE A SOUTH FLOW INTO MID TN WITH SCT-BKN CLOUDS. A STRAY SHRA/TSRA CANNOT BE RULED OUT...BUT PROB TOO LOW TO INCUDE IN TAFS. 13 PREV DISCUSSION... /ISSUED 355 AM CDT THU SEP 19 2013/ DISCUSSION... FORECAST REASONING WILL LEAN TOWARD A CONSENSUS MODEL SOLUTION COMPROMISE FOR THE FORECAST PERIOD UNLESS OTHERWISE NOTED. FORECAST QUANDARIES...PATCHY FOG POTENTIAL THRU THE MID MORNING HRS TODAY...SHWR/TSTM CHANCES ESPECIALLY IN ASSOCIATION WITH FRONTAL PASSAGE FRI NIGHT INTO SAT ALONG WITH POTENTIAL OF THIS BRINGING HEAVY RAINFALL TO THE MID STATE...OVERALL WX PATTERN SAT NIGHT INTO THE FIRST PART OF NEXT WEEK...AND TEMPS. WITH MOST OF THE MID STATE EXPERIENCING CLR SKIES THIS MORNING...AND WITH TEMPS/DEWPOINTS MAINLY IN THE LOW TO MID 60S ALONG WITH CALM WINDS...DO EXPECT SOME PATCHY FOG TO FORM IN THE USUAL FOG PRONE LOCATIONS AND NEAR BODIES OF WATER AND LAST THRU THE MID MORNING HRS. OTHERWISE...WITH RIDGING INFLUENCES STILL DEPICTED BY MODEL CONSENSUS TO BECOME A LITTLE BIT MORE ENHANCED THRU THE MORNING HRS ON FRI...WILL ONLY INTRODUCE A SLIGHT CHANCE OF SHWRS LATE MORNING WITH A SLIGHT CHANCE OF SHWRS/TSTMS BY THE AFTERNOON HRS WITH AFTERNOON HIGH TEMPS BEING AROUND 5 DEGREES OR SO ABOVE SEASONABLE NORMAL VALUES UNDER PTCLDY SKIES. HIGHS WILL BE IN THE MID TO UPPER 80S... LOWER 80S PLATEAU. WILL KEEP THE MID STATE DRY TONIGHT AGAIN UNDER PTCDLY SKIES WITH THE POSSIBILITY OF YET AGAIN PATCHY FOG ACROSS USUAL FOG PRONE LOCATIONS AND NEAR BODIES OF WATER THRU THE EARLY MORNING HRS...WITH A SLIGHT CHANCE OF SHWRS/TSTMS ACROSS WRN PORTIONS OF THE MID STATE THRU THE MID FRI MORNING HRS WITH THAT PATCHY FOG CONTINUING ACROSS CNTRL AND ERN PORTIONS OF THE MID STATE DURING THIS TIME PERIOD ALSO. LOWS TONIGHT ARE EXPECTED TO BE IN THE LOW TO MID 60S...AROUND 60 PLATEAU. STILL LOOKS LIKE A PRONOUNCED UPPER LEVEL TROUGH WILL DEVELOP TO OUR W IN ASSOCIATION WITH A SFC COLD FRONT...WITH THEN BOTH APPROACH FRI NIGHT AND THEN MOVE ACROSS THE MID STATE AS THE DAY PROGRESSES ON SAT. GFS SHOWING A LITTLE BIT MORE ENHANCED LOW LEVEL JET DYNAMICS MAINLY ACROSS SRN AND ERN/PLATEAU PORTIONS OF THE MID STATE BY SAT MORNING WITH PRECIP WATER AMOUNTS APPROACHING AND EVEN SLIGHTLY OVER TWO INCHES. IN LOOKING AT OTHER FORECAST SOUNDINGS...GFS THE MOST AGGRESSIVE HERE WITH PRECIP WATER VALUES ALONG WITH THE ABOVE MENTIONED LOW LEVEL JET STRUCTURE AND THUS PRODUCING SOME HIGH QPF VALUES FOR THE MID STATE FRI NIGHT INTO THE FIRST HALF OF SAT. IN LOOKING AT LATEST WPC QPF FORECAST ALONG WITH THE OTHER MODELS...AM AT THIS TIME INCLINED TO BE A LITTLE CONSERVATIVE HERE AS THIS SYSTEM IS NOT EXPECTED TO BRING A SIGNIFICANT FORCING...INSTABILITY...OR TEMP AIRMASS CONTRAST WITH IT...THUS WILL GO WITH SLIGHTLY LOWER QPF VALUES THRU THIS TIME PERIOD. HOWEVER...CAN NOT RULE OUT THE HEAVY RAINFALL POTENTIAL... BUT THINK AT THIS TIME THAT ANY TYPE OF FLOODING WOULD BE LOCALIZED AND MINOR AT BEST PER HIGH FFG VALUES AND RAINFALL NOT HAVING BEEN RECEIVED OVER WIDE AREAS DURING THE PAST FEW DAYS AND WHAT IS EXPECTED TO HAPPEN UP UNTIL FRI NIGHT. HOWEVER...TO GIVE A HEADS UP POTENTIAL ON THIS HEAVY RAINFALL POSSIBILITY...WILL GO AHEAD AND MENTION IN THE MORNING`S HWO ISSUANCE. OTHERWISE...HAVE MENTIONED INCREASING CHANCES OF SHWR/TSTMS E TO W AS THE DAY PROGRESSES ON FRI WITH THE ABOVE MENTIONED LIMITED INSTABILITY KEEPING ONLY A CHANCE OF TSTMS THRU FRI NIGHT INTO SAT. HAVE INCREASED POPS TO CAT MOST LOCATIONS AFTER MIDNIGHT FRI NIGHT...LIKELY S AND PLATEAU...AND WILL CONTINUE THE TREND OF DECREASING CHANCES OF SHWRS/TSTMS W TO E AS THE DAY PROGRESSES ON SAT. HIGHS ON FRI WILL CONTINUE THE TREND OF 5 DEGREES OR SO ABOVE SEASONABLE NORMAL VALUES WITH LOWS FRI NIGHT MAINLY IN THE LOW TO UPPER 60S...WITH HIGHS ON SAT...AS THE FRONT MOVES THRU ALONG WITH THE UPPER LEVEL TROUGH...NEAR OR ACTUALLY BELOW SEASONABLE NORMAL VALUES WITH HIGHS MAINLY IN THE MID TO UPPER 70S. AS FOR SAT NIGHT INTO THE MID PORTION OF NEXT WEEK...THRU THE FIRST PART OF NEXT WEEK...WILL TREND CLOSE TO CURRENT FORECAST REASONING WITH A SLIGHT CHANCE TO CHANCE OF SHWRS ACROSS AT LEAST ERN AND PLATEAU COUNTIES SAT NIGHT...BUT AM LEANING TOWARD KEEPING THE MID STATE DRY ON SUN WITH RIDGING INFLUENCES BUILDING ACROSS THE MID STATE PROVIDING DRY CONDITIONS AND A RETURN TOWARD TEMPS NEAR SEASONABLE NORMS. EVEN THOUGH THERE ARE SOME TIMING DIFFERENCES IN MODELS...UNLIKE AT THIS TIME YESTERDAY...IT DOES NOT LOOK LIKE ANY OF THE MODELS ARE ADVERTISING ANY TYPE OF CLOSED UPPER LEVEL LOW DEVELOPMENT BEHIND THE ABOVE MENTIONED FRONTAL SYSTEM THAT WOULD SUBSTANTIALLY AFFECT THE MID STATE. THE LATEST EURO DOES DEVELOP A CLOSED LOW ACROSS CNTRL MS BY MON MORNING BUT MOVES IT WELL SOUTH OF THE MID STATE AND THEN OPENS IT UP BY TUE...POSSIBLY BRINGING SOME WRAP AROUND ADDITIONAL MOISTURE TO THE MID STATE DURING THE FIRST PART OF NEXT WEEK. WITH THIS OVERALL...AND MORE LIKELY TO OCCUR...CHANGE IN CONSENSUS MODEL SOLUTIONS...WILL GO CLOSE TO CURRENT FORECASTED WX CONDITIONS ACROSS THE MID STATE DURING THIS TIME PERIOD. 31 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 07
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
1219 PM CDT THU SEP 19 2013 .UPDATE...AVIATION DISCUSSION. && .PREV DISCUSSION... /ISSUED 1039 AM CDT THU SEP 19 2013/ DISCUSSION...12Z UPPER AIR ANALYSIS PLACES AN UPPER LEVEL RIDGE AXIS OVER THE SOUTHEAST UNITED STATES THIS MORNING. CONSEQUENTLY...RAIN FREE WEATHER IS OCCURRING ACROSS THE MID SOUTH WITH ANY CONVECTIVE ACTIVITY OCCURRING THUS FAR OVER THE OHIO VALLEY AND PORTIONS OF THE UPPER MID WEST AND NORTHERN/CENTRAL PLAINS. AS OF 10 AM CDT...TEMPERATURES ARE IN THE UPPER 70S TO AROUND 80 DEGREES AT MOST LOCATIONS. LATEST SHORT TERM MODEL TRENDS INDICATE THE POTENTIAL FOR SOME ISOLATED TO PERHAPS SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP FROM DAYTIME HEATING ACROSS PORTIONS OF THE MID SOUTH...MAINLY ALONG AND WEST OF THE MISSISSIPPI RIVER WHERE BETTER LOW LEVEL MOISTURE RESIDES. AT THIS TIME...FEEL THE LATEST 3KM HRRR AND RUC MAY BE HANDLING THE CONVECTIVE POTENTIAL THE BEST. WILL UPDATE FORECAST TO ADJUST POPS ACCORDINGLY...AND MAKE ADJUSTMENTS TO TEMPERATURES...CLOUD COVER AND ALL OTHER ELEMENTS AS NEEDED. UPDATED GRIDS WILL BE AVAILABLE SHORTLY. CJC PREV DISCUSSION... /ISSUED 709 AM CDT THU SEP 19 2013/ DISCUSSION... UPDATED FOR 12Z AVIATION DISCUSSION PREV DISCUSSION... /ISSUED 350 AM CDT THU SEP 19 2013/ SKIES ARE MOSTLY CLEAR ACROSS MUCH OF THE FORECAST AREA THIS MORNING WITH TEMPERATURES RANGING FROM THE MID 60S TO MID 70S. TODAY SHOULD BE FAIRLY SIMILAR TO YESTERDAY WITH SOME SCATTERED THUNDERSTORMS FORMING MAINLY DURING THE AFTERNOON HOURS ACROSS THE NORTHERN HALF OF THE FORECAST AREA. TEMPERATURES WILL REMAIN QUITE WARM AGAIN TODAY WITH HIGHS IN THE MID 80S TO AROUND 90 DEGREES. BY TONIGHT...A COLD FRONT WILL BE MOVING THROUGH THE CENTRAL PLAINS AND INTO SOUTHWEST MISSOURI. AHEAD OF THE FRONT SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP WITH SOME OF THIS ACTIVITY REACHING MAINLY WESTERN SECTIONS OF THE FORECAST AREA. ON FRIDAY THE COLD FRONT WILL START MOVING THROUGH ARKANSAS SO THE CHANCE OF RAIN WILL INCREASE OVER THE FORECAST AREA WITH THE BEST CHANCE OF THUNDERSTORMS WEST OF THE MISSISSIPPI RIVER. THIS MODEL RUN SEEMS TO BRING THE COLD FRONT THROUGH THE FORECAST AREA FASTER THAN PREVIOUS RUNS SO THAT THE FRONT WILL BE JUST ABOUT OUT OF THE REGION BY SATURDAY MORNING. FRIDAY NIGHT SHOULD BE QUITE WET AS THE FRONT MOVES THROUGH. ON SATURDAY RAIN CHANCES WILL DIMINISH FROM NORTHWEST TO SOUTHEAST AS COOLER AND DRIER AIR BEGIN TO MOVE IN. TEMPERATURES ON SATURDAY WILL BE A FEW DEGREES COOLER THAN NORMAL WITH HIGHS AROUND 80 DEGREES EXPECTED FOR MUCH OF THE FORECAST AREA. BY SATURDAY NIGHT...THE EXTREME SOUTHEAST CORNER OF THE FORECAST AREA IS THE ONLY AREA THAT MIGHT SEE AN ISOLATED SHOWER. BY SUNDAY HIGH PRESSURE WILL IN CONTROL OF THE WEATHER FOR MUCH OF THE EASTERN U.S. INCLUDING THE FORECAST AREA. THIS WILL MEAN ANOTHER PERIOD OF DRY WEATHER FROM SUNDAY THROUGH WEDNESDAY. TEMPERATURES WILL REMAIN SLIGHTLY BELOW NORMAL SUNDAY AND MONDAY BUT WINDS SHOULD BEGIN TO SHIFT TO THE SOUTH BY TUESDAY ALLOWING FOR WARMER AIR TO RETURN TO THE REGION WITH ABOVE NORMAL TEMPERATURES EXPECTED FOR TUESDAY AND WEDNESDAY. ARS .AVIATION...18Z TAF CYCLE VFR CONDS WILL PREVAIL THROUGHOUT THE PERIOD. A FEW SHOWERS AND THUNDERSTORMS MAY DEVELOP THIS AFTERNOON BUT COVERAGE IS NOT EXPECTED TO BE ENOUGH TO INCLUDE IN TAFS. WILL AMEND AS NECESSARY BASED ON RADAR TRENDS. WINDS WILL BE SOUTH AT 8-12 KTS...ONLY DIMINISHING SLIGHTLY OVERNIGHT IN ADVANCE OF A COLD FRONT. A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS IS EXPECTED LATE IN THE FORECAST PERIOD. WILL LIKELY ADD PREVAILING SHOWERS IN LATER UPDATES...WILL START WITH VCSH AT ALL SITES TOMORROW BETWEEN 10Z AT JBR AND 16Z AT TUP. MEM AND MKL SHOULD SEE SHOWERS AROUND 14Z. && .PRELIMINARY POINT TEMPS/POPS... MEM 91 72 85 68 / 20 30 80 70 MKL 90 68 85 64 / 20 20 60 70 JBR 92 71 82 63 / 20 30 90 50 TUP 90 68 88 70 / 10 10 50 80 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...NONE. MO...NONE. MS...NONE. TN...NONE. && $$