Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/25/14


AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
550 PM MDT SUN AUG 24 2014 .UPDATE... ISSUED AT 550 PM MDT SUN AUG 24 2014 SHORT TERM UPDATE WILL BE REQUIRED EARLY THIS EVENING AS CONVECTION HAS INCREASED ACROSS EAST CENTRAL UTAH. THIS ACTIVITY MAY EXPAND INTO NW COLORADO...POSSIBLY AS FAR AS A LINE FROM MOAB TO ASPEN. THIS ACTIVITY IS IN RESPONSE TO EMBEDDED DISTURBANCE ALONG A SHEAR AXIS THAT CUTS ACROSS THE FORECAST AREA THIS EVENING. RAP AND HRRR MODELS INDICATE THAT SHOWERS AND STORMS LASTING WELL BEYOND SUNSET WILL OCCUR FROM VERNAL TO ROUTT COUNTY. IT APPEARS THAT THE LOWER RESOLUTION SUCH AS THE GFS40 IS SUGGESTING NOCTURNAL CONVECTION AS WELL. UPDATE WILL BE COMING AND WILL BE LEANING TOWARDS THE RAP/HRRR MODELS. && .SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT) ISSUED AT 255 PM MDT SUN AUG 24 2014 12Z H5 HAND ANALYSIS SHOWING A BLOCKING RIDGE EXTENDING FROM THE GULF STATES UP INTO THE CANADIAN MARITIME REGION. AS SUCH LOW PRESSURE WILL BE ANCHORING IN THE WESTERN STATES TO START OUT THE NEW WEEK. THE MORE IMPRESSIVE FEATURES SHOWING UP IN WATER VAPOR THIS AFTERNOON ARE THE PAIR OF LOWS ROTATING AROUND EACH OTHER OVER MONTANA AND WASHINGTON THIS AFTERNOON. THE FORMER RETREATING NORTHEASTWARD AND THE LATTER DROPPING SOUTHWARD WHERE IT WILL CARVE OUT A FAIRLY AMPLIFIED TROUGH THROUGH THE GREAT BASIN BY EARLY TUESDAY. DERIVED IMAGERY AND RAOB DATA SHOWS A SIGNIFICANT DECREASE IN MOISTURE THE PAST 24 HOURS AS THE MONSOONAL PLUME HAS BEEN DIRECTED INTO THE EASTERN PLAINS. AT GJT AND UPSTREAM PWATS ARE BELOW NORMAL FOR THIS TIME OF YEAR. THERE ARE SOME RETURNS SHOWING UP ON RADAR WITH LOW LEVEL MOISTURE...MOUNTAIN CIRCULATIONS AND INSTABILITY BEING ENHANCED BY A JET ALOFT. THE FOCUS FOR OVERNIGHT SHOULD MAINLY BE ACROSS THE NORTH WHERE VEERING MID LEVEL PROFILES AND THE PASSING JET MAXIMA WILL ADD JUST ENOUGH ASCENT TO KEEP NOCTURNAL CONVECTION FIRING. HAVE THROWN OUT THE AGGRESSIVE GFS QPF OUTPUT ATTM WITH IT NOT VERIFYING SO FAR THIS AFTERNOON. THETA SURFACES NEAR 315K SHOW DECENT UPGLIDE NORTH OF INTERSTATE 70 TONIGHT WHILE ALSO HINT AT SOME TAP TO THE TROPICAL MOISTURE LEFT OVER FROM WHAT IS LEFT OF MARIE. THIS TAP DOES NOT LOOK TO GREATLY ENHANCE THE MOISTURE ADVECTION TONIGHT BUT MAY PLAY SOME ROLE IN STORM FORMATION OVER THE EASTERN DIVIDE MOUNTAINS FOR MONDAY. AGAIN MONDAY LOOKS TO BE SOMEWHAT OF A DOWN DAY AS THE JET ALOFT WEAKENS AND OVERALL PWATS REMAIN BELOW NORMAL. A SMALL RIBBON OF THE MOISTURE MENTIONED ABOVE LOOKS TO FAVOR CONVECTION OVER THE CENTRAL DIVIDE MOUNTAINS UNDER CONFLUENT FLOW ALOFT. THIS ALL HANDLED WELL IN THE GOING GRID FORECAST SO ONLY SMALL TWEAKS NEEDED. TEMPERATURES SHOULD BE A BIT MORE MILD OVERNIGHT UNDER WAA AND PUSH SOME 3 TO 7 DEGREES UPWARD FOR TUESDAY. TUESDAY NIGHT THE FLOW BACKS MORE SOUTHERLY ALOFT AS THE MAIN TROF AXIS BECOME ORIENTED MORE MERIDIONALLY. MONSOON AND TROPICAL MOISTURE LOOK TO BE FORCED NORTHWARD IN THIS FLOW AND THERE SHOULD BE AN INCREASE IN CONVECTION FROM MIDNIGHT TOWARD SUNRISE...SETTING UP A MORE ACTIVE DAY FOR TUESDAY. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 255 PM MDT SUN AUG 24 2014 THE CHALLENGE OF THESE PERIODS HAS BEEN THE TIMING AND THEREFORE THE PLACEMENT OF THE UPPER LOW THAT WILL DIG OVER THE REGION. THE EC AND NAM ARE IN GOOD AGREEMENT WITH A SLOWER SOLUTION. THE GFS AND CANADIAN PRODUCE A FASTER PROGRESSION BUT THE GFS IS SLOWER THAN ITS PREVIOUS RUNS. AS THE UPPER LOW IS DECOUPLED FROM THE POLAR FRONT JET...THE SLOWEST EC SOLUTION IS PREFERED. SO INCREASED STORM COVERAGE AND COOLER TEMPS ARE EXPECTED THROUGH THURSDAY. TUESDAY...THE UPPER LOW DUG INTO EASTERN NEVADA ENHANCING A 75KT JET OVER THIS CWA. MOISTURE SURGES TO OVER AN INCH PRECIPITABLE WATER VALUES IN SE UTAH. WEDNESDAY THE UPPER LOW SLOWLY PROGRESSES INTO NE UTAH LOSING JET SUPPORT BUT GAINING CYCLONIC AND DIVERGENT FLOW ALOFT. PRECIP WATER VALUES REMAIN NEAR ONE INCH. STORM MOTION ALSO REMAINS BRISKLY TO THE NE AT 20 KTS LIMITING RAINFALL FORM ANY SINGLE STORM. BY THURSDAY THE LOW CENTER AMBLES TO THE CONTINENTAL DIVIDE WITH WRAP-AROUND DYNAMICS ACROSS THE NORTHERN CWA AND THE UPPER FLOW SWITCHING TO NW. SOME NOCTURNAL STORMS ARE EXPECTED THROUGH THESE PERIODS. BY FRIDAY THE EC PROGRESSES THE OPENING LOW ONTO THE EASTERN PLAINS WITH A RIDGE BUILDING IN FROM THE WEST. FRIDAY STORM ACTIVITY WILL LINGER ALONG THE CONTINENTAL DIVIDE...THEN A DRYING AND WARMING TREND INTO THE WEEKEND. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 550 PM MDT SUN AUG 24 2014 EVENING NOCTURNAL SHRA/TSRA WILL BE POSSIBLE ACROSS NE UTAH INTO NW COLORADO...THIS INCLUDES THE TAF SITE AT KVEL WITH TSRA IN THE VICINITY OF KGJT AND KRIL. CELLS WILL BE MOVING WSW TO ENE AT ABOUT 20 KNOTS. LOCALIZED WIND GUSTS OF 25-35KTS WILL BE POSSIBLE FROM NEARBY CELLS. CONVECTIVE TURBULENCE IS LIKELY. BETWEEN 12Z-18Z...MINIMAL AVIATION HAZARDS EXPECTED. AFTER 18Z...SCATTERED SHRA/TSRA WILL FORM...PRIMARILY OVER THE MOUNTAINS OF NE UTAH AND WRN COLORADO. THUNDERSTORMS WILL BE IN THE VICINITY OF THESE TAF SITES. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...PF SHORT TERM...15 LONG TERM...JOE AVIATION...PF
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
327 AM MDT SAT AUG 23 2014 .SHORT TERM...(TODAY THROUGH TONIGHT ) ISSUED AT 319 AM MDT SAT AUG 23 2014 A RATHER STG UPPER LEVEL TROUGH WILL MOVE ACROSS THE NRN ROCKIES THRU TONIGHT WITH COLORADO BEING ON THE SRN EDGE OF THE TROUGH. MEANWHILE AN UPPER LEVEL JET WILL REMAIN ACROSS NRN PORTIONS OF THE AREA THRU THIS EVENING WITH SOME POTENTIAL VORTICITY IN THE MID TO UPPER LEVELS. THUS SHOULD SEE A GOOD CHC OF SHOWERS AND TSTMS IN THE MTNS LATER THIS MORNING INTO THE AFTN HOURS. OVER NERN CO LOW LVL MOISTURE WILL MIX OUT SOME THRU THE DAY EXCEPT OVER THE FAR NERN PLAINS. CAPES WILL RANGE FM 500-1000 J/KG ALONG THE FRONT RANGE WHILE OVER THE FAR NERN PLAINS VALES WILL BE ABOVE 1500 J/KG. AS OUTFLOW BOUNDARIES FM CONVECTION OVER THE HIGHER TERRAIN MOVE ACROSS BY EARLY TO MID AFTN EXPECT SCT TSTMS TO DVLP ALONG THE FRONT RANGE AND THEN MOVE RATHER QUICKLY ACROSS THE PLAINS FM LATE AFTN INTO THE EARLY EVEING HOURS. WITH RATHER STG MID LVL FLOW A FEW STORMS COULD PRODUCE WIND GUSTS UP TO 60 MPH. OVER THE FAR NERN PLAINS WHERE CAPES WILL BE BETTER SOME MARGINAL LARGE HAIL COULD OCCUR AS WELL. AS FOR HIGHS WILL KEEP READINGS MOSTLY IN THE LOWER TO MID 80S ACROSS NERN CO. BY THIS EVENING AS DRIER AIR BEGINS TO SPREAD INTO THE MTNS PRECIP SHOULD GRADUALLY DECREASE OVER THE HIGHER TERRAIN. OVER NERN CO PCPN CHANCES SHOULD END BY EARLY EVENING ALONG THE FRONT RANGE AND THEN BY MIDNIGHT OVER THE FAR NERN CORNER. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 319 AM MDT SAT AUG 23 2014 SUNDAY AND SUNDAY NIGHT...THE FLOW ALOFT REMAIN SOUTHWESTERLY. ENOUGH SUBTROPICAL MOISTURE WILL BE AROUND VIA THE GFS/ECMWF MODELS TO KEEP A CHANCE OF TSTMS IN THE AFTN/EVNG. THE BEST CHC WL BE OVER THE MOUNTAINS. ON MONDAY...THE NEXT SYSTEM WILL APPROACH CO FM THE NORTHWEST...WITH A SOUTHWESTERLY FLOW AHEAD OF IT. THUNDERSTORMS WILL AGAIN DEVELOP OVER THE CWFA MONDAY AFTN/EVNG WITH THE TROUGH ITSELF STILL OVER SRN ID/NRN UT BY 12Z TUESDAY. THE ECMWF/NAM ARE SLOER THAN THE MORE PROGRESSIVE GFS WHICH MAINTAINS AN OPEN WAVE TROUGH...THE NAM DRIVES A CLOSED CIRCULATION INTO NORTHERN CA. THE ECMWF IS THE COMPROMISE MDL...IT CLOSES THE UPPER LOW BUT STILL SHIFTS IT EASTWARD ACROSS COLORADO...BUT SLOER...TUESDAY INTO WEDNESDAY. WL FOLLOW THIS PLAN FOR NOW AT BUMP THE POPS UPWARD FOR TUESDAY NIGHT AND WEDNESDAY. THURSDAY AND FRIDAY...WL CONTINUE WITH THE TREND OF DRIER AND WARMER WITH A RIDGE PROGGED TO BUILD OVER THE WESTERN U.S. && .AVIATION...(FOR THE TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 319 AM MDT SAT AUG 23 2014 TRICKY FCST FOR THIS MORNING DUE TO POTENTIAL FOG AS TEMP-DEWPOINT SPREADS ARE LOW AND WINDS ARE LIGHT. HRRR HAS BEEN ALTERNATING BETWEEN DENSE FOG AND NO DENSE FOG WITH EACH SUCCESSIVE RUN WHILE THE RAP HAS SHOWN NOTHING THE ENTIRE TIME. THE HRRR DOES SHOW SOME TYPE OF WK CYCLONE DEVELOPING NR DIA WITH WINDS BECOMING LIGHT NNW AROUND 12Z. IF THIS HAPPENS THEN POTENTIAL FOR DENSE FOG WOULD INCREASE IN THE 12Z-15Z TIME PERIOD. DUE TO UNCERTAINTY OF FCST WILL INTRODUCE A TEMPO GROUP FOR IFR CONDITIONS. FOR THIS AFTN OUTFLOW BOUNDARIES FM MTN CONVECTON WILL PUSH ACROSS BY 21Z WHICH MAY TRIGGER SCT TSTMS. WITH DECENT MID LVL FLOW THE STORMS WILL BE QUICK MOVING BUT COULD PRODUCE WIND GUSTS FM 40-50 MPH. ALSO WITH UPPER LEVEL JET OVERHEAD THIS IS SOME POSSIBILITY FOR STORM REGENERATION INTO THE EARLY EVENING HOURS THRU 02Z. BY MID EVENING THREAT OF STORMS SHOULD END. WINDS WILL BE ESE BY MIDDAY AND THEN SWITCH TO THE WNW BY 21Z AS INITIAL OUTFLOW BOUNDARIES MOVE ACROSS. BY EARLY EVENING WINDS WILL BE LIGHT NNW AND THEN TRANSITION TO DRAINAGE BY 06Z. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...RPK LONG TERM...COOPER AVIATION...RPK
AREA FORECAST DISCUSSION
NWS ALBANY NY
422 PM EDT SAT AUG 23 2014 .SYNOPSIS... HIGH PRESSURE WILL GRADUALLY TAKE HOLD ACROSS THE REGION TONIGHT INTO SUNDAY. THIS HIGH PRESSURE SYSTEM WILL REMAIN OVER THE EASTERN SEABOARD INTO THE MIDDLE OF THE UPCOMING WEEK...BRINGING WARM AND DRY SUMMER WEATHER TO THE ALBANY FORECAST AREA. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... CLOUDS ARE HANGING TOUGH ACROSS THE FORECAST AREA THIS AFTERNOON. SURFACE WINDS ARE LIGHT AND GENERALLY FROM THE NORTHEAST. TEMPERATURES RANGE FROM THE 60S IN THE HILLS TO THE 70S IN THE VALLEYS. RADAR SHOWS A FEW VERY LIGHT SHOWERS OR SPRINKLES SCATTERED ACROSS THE AREA. LATEST 17Z RAP MODEL SHOWS LOW CLOUDS LINGERING UNTIL SHORTLY AFTER MIDNIGHT TONIGHT. HI-RES RAPID REFRESH MODEL SHOWS A SLIGHT CHANCE OF A SHOWER CONTINUING UNTIL SUNSET. THE HI-RES WRF AGREES WITH THE THREAT FOR ANY SHOWERS ENDING AFTER SUNSET. SKIES SHOULD GRADUALLY CLEAR OVERNIGHT...AND BASED ON TEMP/DEWPOINT/WINDS FORECAST OVERNIGHT...EXPECT AREAS OF FOG TO FORM IN THE VALLEYS. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... FOG AND/OR LOW CLOUDINESS WILL DISSIPATE SUNDAY MORNING LEAVING A MOSTLY SUNNY DAY. SOME AFTERNOON CLOUDS MAY DEVELOP OVER THE HIGHER TERRAIN WITH THE HEATING FROM THE SUN. MODELS HAVE THE AREA DRY TOMORROW SO KEPT POPS BELOW 15 PERCENT. HIGHS ON SUNDAY WILL RANGE FROM THE MID 70S IN THE HILLS TO LOW 80S IN THE VALLEYS. SUNDAY NIGHT...MOSTLY CLEAR SKIES AND LIGHT WINDS WILL LEAD TO THE DEVELOPMENT OF VALLEY FOG. IT IS THE BEGINNING OF FOG SEASON AND CONDITIONS LOOK GOOD AGAIN FOR VALLEY FOG FORMATION. THIS FOG WILL DISSIPATE MONDAY MORNING LEAVING A MOSTLY SUNNY AND WARM DAY. EXPECT MONDAY TO BE DRY UNDER HIGH PRESSURE. HIGHS MONDAY IN THE UPPER 70S HILLS TO MID 80S VALLEYS. && .LONG TERM /TUESDAY THROUGH SATURDAY/... HIGH PRESSURE WILL REMAIN AT ALL LEVELS OF THE ATMOSPHERE...THROUGH EARLY WEDNESDAY. THIS WILL CONTINUE OUR TRANQUIL LATE SUMMER WEATHER WITH SLIGHTLY ABOVE NORMAL TEMPERATURES ALONG WITH A GOOD DEAL OF SUNSHINE. WEDNESDAY INTO THURSDAY....IT LOOKS AS IF A WEAK COLD FRONT WILL CROSS THE REGION WITH PERHAPS A FEW SHOWERS AND THUNDERSTORMS...BUT WITH WEAK FORCING...CONVECTION COULD BE FAR AND FEW BETWEEN. THE FRONT HOWEVER...LOOKS TO GET HUNG UP SOMEWHERE OVER OUR REGION OR A LITTLE SOUTH OF IT. IT COULD COME BACK AS A WARM FRONT...WHILE PERHAPS A STRONGER COLD FRONT ATTEMPTS TO MAKE IT THROUGH ON SATURDAY OR SUNDAY WITH A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS. THE TROPICS CONTINUE TO TRY TO FLARE UP. WE COULD HAVE OUR THIRD TROPICAL NAMED STORM...WHICH WOULD BE NAMED CRISTOBAL BY SUNDAY. ALMOST ALL GUIDANCE KEEPS THIS STORM SOUTH AND EAST OF OUR REGION. HOWEVER...THERE COULD BE SOME INDIRECT IMPACTS OF THIS STORM...PERHAPS YIELDING A PREDECESSOR RAIN EVENT (PRE) OVER OR NEAR REGION NEXT WEEKEND...FOCUSED ON EITHER THE WARM OR COLD FRONT. THE TROPICAL SYSTEM COULD ALSO PUMP THE RIDGE OVER US...BLOCKING ANY COLD FRONT FROM MOVING SOUTH. BOTTOM LINE...THE EXTENDED PERIOD STARTS WARM AND DRY...BECOMING MORE UNCERTAIN WITH TIME BUT LIKELY TEMPERATURES STAYING AT OR EVEN A LITTLE ABOVE NORMAL. HUMIDITY WILL START OUT MODERATE (DEWPOINTS AROUND 60) PERHAPS CREEPING INTO THE 60S WITH TIME. LOOK FOR HIGHS GENERALLY IN THE 80S IN THE VALLEYS (75-80 HIGHER TERRAIN) THROUGHOUT THE PERIOD...LOWS WILL RANGE FROM THE UPPER 50S TO MID 60S. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... LOOKING AT VFR CONDITIONS THROUGH MOST OF THE EVENING. THEN...AS TEMPERATURES FALL TO THE FORECAST "CROSSOVER" TEMPERATURES IN THE LOWER 50S...ALONG WITH A SOMEWHAT DAMP GROUND FROM ALL THE THURSDAY AND FRIDAY/S RAINFALL...NO WIND AND INITIALLY FEW IF ANY SENSIBLE CLOUDS...FOG WILL LIKELY FORM AT ALL THE TAF SITES DURING THE OVERNIGHT PERIOD. WE BELIEVE THE FOG WILL BE MAINLY IFR (2SM BR) AT KGFL AND KPSF...BEGINNING AT 06Z AND 08Z RESPECTIVELY. AT THE TWO OTHER SITES SINCE TEMPERATURES ARE PROJECTED NOT TO GET AS LOW...WE WENT WITH MVFR MIST (3SM BR)..AFTER 08Z. WE ALSO INCLUDE IFR CIGS AT KGFL AND KGFL AS THE FOG COULD ACTUALLY GET RATHER DEEP. IT LOOKS AS IF THE FOG SHOULD BURN OFF BETWEEN 1130Z-1200Z ON SUNDAY. AFTER THAT...NO AVIATION WEATHER RELATED PROBLEMS ARE EXPECTED ON SUNDAY WITH GOOD VISIBILITY AND ONLY FEW-SCT CU AT THE 5-6KFT. THE N-NE 5-10KT SURFACE WIND SHOULD BECOME CALM TONIGHT...THEN 5-10KTS ON SATURDAY. OUTLOOK... SUNDAY NIGHT: NO OPERATIONAL IMPACT. AREAS FG. MONDAY: NO OPERATIONAL IMPACT. NO SIG WX. MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. TUESDAY: NO OPERATIONAL IMPACT. NO SIG WX. TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX. WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...TSRA. THURSDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...TSRA. && .FIRE WEATHER... RH VALUES WILL RISE TO NEAR 100 PERCENT OVERNIGHT WITH GRADUALLY CLEARING SKIES. EXPECT AREAS OF VALLEY FOG AND WIDESPREAD DEW TO FORM OVERNIGHT. WINDS WILL BE LIGHT AND VARIABLE. ON SUNDAY RH VALUES DROP TO BETWEEN 40 AND 50 PERCENT UNDER PARTLY SUNNY SKIES. WINDS WILL BE LIGHT AND FROM THE NORTHEAST. RH VALUES WILL INCREASE TO NEAR 100 PERCENT SUNDAY NIGHT WITH LIGHT AND VARIABLE WINDS. AREAS OF VALLEY FOG AND WIDESPREAD DEW WILL FORM AGAIN. WINDS WILL BE LIGHT AN VARIABLE. && .HYDROLOGY... NO HYDROLOGIC ISSUES ARE EXPECTED THROUGH THE NEXT FIVE DAYS. LITTLE PRECIPITATION IS EXPECTED. RIVER AND LAKE LEVELS WILL GRADUALLY RECEDE DURING THE PERIOD. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...SND NEAR TERM...SND SHORT TERM...SND LONG TERM...HWJIV AVIATION...HWJIV FIRE WEATHER...SND HYDROLOGY...SND
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
233 PM EDT SAT AUG 23 2014 ...HEAT ADVISORY ALL AREAS REST OF TODAY... .CURRENTLY...A SCT-BKN CU FIELD HAS DEVELOPED IN PREVAILING NWLY FLOW WITH A VERY HOT DAY ONGOING. A FEW OBS SHOW UPPER 90S AND 100 AT THIS TIME WITH A FEW HEAT INDICES OF AROUND 110 BEING REPORTED. SOME LOW LEVEL MIXING WILL CONTINUE AND HELP LIMIT HEAT INDICES SOMEWHAT. RAP SOUNDING SHOW A VERY DRY AIRMASS UNDER CLOUD BASES OVER SE GA AND MORE MOIST OVER NE FL WHERE PWATS ARE ABOUT 1.8 INCHES. A FEW SHOWERS HAVE POPPED OVER INLAND AREAS AND ALONG THE E COAST. AS EXPECTED THE E COAST SEA BREEZE IS STILL VERY NEAR THE COAST...BUT WILL CONTINUE TO MAKE A SLOW AND STEADY PROGRESS INLAND. FOR REST OF THE AFTN...ISOLD TO SCT SHOWERS AND STORMS WILL DEVELOP WITH THE BEST CHANCES GENERALLY OVER THE SRN 2/3RDS OF THE AREA. CONVECTION WILL LIKELY END BY AROUND MIDNIGHT TO 1 AM FOR MY INLAND NE FL ZONES. AN ISOLD STRONG STORM IS POSSIBLE. REST OF TONIGHT...MUGGY OVERNIGHT LOWS IN THE MID TO LOCALLY UPPER 70S WITH LIGHT WINDS. .SHORT TERM...FRONTAL BOUNDARY WILL SINK SOUTH TO NEAR FL/GA LINE BY SUNDAY AFTERNOON...THEN INTO CENTRAL FL SUNDAY NIGHT. THIS BOUNDARY WILL BE A FOCUS FOR SHOWERS/STORMS AS IT PASSES. THE BOUNDARY SHOULD REACH SE GA COUNTIES SUNDAY MORNING...THEN SINK SOUTH OF FORECAST AREA AROUND MIDNIGHT SUNDAY NIGHT. HIGH PRESSURE WILL PUSH SOUTH BEHIND THIS BOUNDARY...WHICH WILL LIMIT PRECIPITATION POTENTIAL ON MONDAY. WILL HAVE PRECIPITATION OVER NORTHEAST FLORIDA...DUE TO POSSIBLE OUTER MOISTURE BANDS FROM POTENTIAL TROPICAL SYSTEM. TEMPERATURES WILL BE A FEW DEGREES COOLER ON SUNDAY DUE TO CLOUDS AND PRECIPITATION COVERAGE. WITH INCREASING ONSHORE FLOW...MOST LOCATIONS WILL LIKELY REMAIN AT OR BELOW 90 ON MONDAY. .LONG TERM.../MONDAY NIGHT THROUGH SATURDAY/... THE FORECAST DURING THIS PERIOD WILL BE DRIVEN BY THE POTENTIAL FOR A TROPICAL SYSTEM TO FORM. AT THIS TIME...INDICATIONS CONTINUE TO BE FOR THIS SYSTEM TO PASS TO THE EAST OF THE AREA. WITH THIS...COULD HAVE PRECIPITATION OVER EASTERN COUNTIES...WITH MAINLY DRY CONDITIONS FURTHER INLAND. WITH THE FORECAST TRACK FOR THIS POTENTIAL TROPICAL SYSTEM STILL BEING UNCERTAIN...HAVE KEPT WITH CURRENT FORECAST GRIDS FOR THIS PERIOD. MAX TEMPERATURES WILL LIKELY BE A FEW DEGREES BELOW NORMAL THROUGH MID WEEK...THEN RETURN TO NEAR TO ABOVE NORMAL LATER IN THE PERIOD. && .AVIATION...INCLUDED VCSH FOR NOW FOR FL TAFS WITH VCTS BEGINNING IN A COUPLE OF HOURS. STILL LOOKS LIKE BEST CHANCE OF TSTM OCCURRING AT GNV SO INSERTED TEMPO GROUP 21Z-24Z. VFR SHOULD PREVAILING AFTER 00Z. && .MARINE...SELY WINDS THIS EVENING WILL TURN BACK TO THE W BY SUN MORNING. NORTHEAST WINDS WILL BEGIN TO INCREASE ON SUNDAY BEHIND A BACKDOOR COLD FRONT WITH AN EXTENDED PERIOD OF ONSHORE FLOW EXPECTED THROUGH THE MIDDLE OF NEXT WEEK. SMALL CRAFT ADVISORY CONDITIONS WILL BE POSSIBLE EARLY NEXT WEEK AS THE PRESSURE GRADIENT TIGHTENS WITH HIGH PRESSURE BUILDING DOWN THE COAST AND A POSSIBLE TROPICAL SYSTEM PASSING OVER THE WRN ATLC WATERS BUT LARGE UNCERTAINTY REMAINS ON THE EXACT TRACK. SEAS WILL BE DEPENDENT ON STRENGTH AND TRACK OF ANY TROPICAL SYSTEM BUT FOR NOW GIVEN THE CONSIDERABLE DEGREE OF UNCERTAINTY WE WILL CAP THE SEAS AT 7 FT. RIP CURRENTS: LOW RISK TODAY THEN MODERATE RISK EXPECTED TOMORROW AS ONSHORE FLOW DEVELOPS. && .CLIMATE... A FEW RECORD HIGHS ARE EXPECTED TO AT LEAST BE TIED TODAY. RECORD HIGHS TODAY JAX 98/1966 GNV 99/1902 AMG 99/1968 SSI 95/2006 && .PRELIMINARY POINT TEMPS/POPS... AMG 75 96 75 91 / 10 40 40 10 SSI 79 88 77 85 / 20 30 40 40 JAX 76 94 77 88 / 20 30 40 40 SGJ 76 90 78 87 / 10 20 40 40 GNV 75 95 73 88 / 30 50 50 20 OCF 75 95 74 89 / 30 50 50 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ALACHUA-BAKER- BRADFORD-CLAY-COLUMBIA-DUVAL-FLAGLER-GILCHRIST-HAMILTON- MARION-NASSAU-PUTNAM-ST JOHNS-SUWANNEE-UNION. GA...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR APPLING-ATKINSON- BACON-BRANTLEY-CHARLTON-CLINCH-COASTAL CAMDEN-COASTAL GLYNN- COFFEE-ECHOLS-INLAND CAMDEN-INLAND GLYNN-JEFF DAVIS-PIERCE- WARE-WAYNE. AM...NONE. && $$ SHASHY/STRUBLE/GUILLET
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
957 AM EDT SAT AUG 23 2014 UPDATE... HIGH PRESSURE ALOFT AND AT THE SURFACE WILL CONTINUE ACROSS THE REGION TODAY. LATEST RUNS OF THE HRRR KEEP CONVECTION VERY SPARSE ACROSS THE CWFA TODAY...AND LOW END SCT/ISOLD POPS STILL LOOK GOOD. DO THINK ANY CONVECTIVE ACTIVITY THAT DOES DEVELOP WILL BE TERRAIN BASED...OR DEPENDENT UPON ANY MESOSCALE BOUNDARIES. MODIFIED SOUNDING DOES SHOW SOME VERY GOOD SURFACE INSTABILITY PRESENT. SOUNDING ALSO ALSO SHOWS PLENTY OF DRY AIR ALOFT. SO...IF THUNDERSTORMS ARE ABLE TO DEVELOP...THEY WOULD LIKELY BE ABLE TO PRODUCE GUSTY WINDS AND FREQUENT LIGHTNING STRIKES. ISOLD SEVERE IS POSSIBLE...BUT THE POTENTIAL REMAINS LOW DUE TO VERY LITTLE CONVECTIVE COVERAGE EXPECTED. WILL ALSO BE EXTENDING THE HEAT ADVISORY NORTHWARD ON THE SW SIDE. PREV DISCUSSION... /ISSUED 721 AM EDT SAT AUG 23 2014/ SHORT TERM /TODAY THROUGH SUNDAY/... /ISSUED AT 347 AM EDT SAT AUG 23 2014/ BIG CHANGES ON TAP THROUGH THE SHORT TERM PERIOD AS MODELS CONTINUE TO SHOW JUST ONE MORE HOT DAY BEFORE A WELCOMED BACK DOOR COLD FRONT SWEEPS ACROSS THE AREA ON SUNDAY. FOR TODAY... THE DOMINATING UPPER RIDGE BEGINS TO RETREAT WESTWARD AS A SERIES OF DISTURBANCES TRACK DOWN THE EASTERN PERIPHERY AND ACROSS THE STATE DURING THE AFTERNOON AND OVERNIGHT HOURS. THIS WILL WARRANT SHOWING A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE NORTH AND EAST CENTRAL PORTIONS OF THE FORECAST AREA TODAY... AND HOLDING ONTO A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS FOR ALL AREAS TONIGHT. THE CONTINUED HEAT AND STRONG INSTABILITY COUPLED WITH SOME UPPER SUPPORT SUGGEST THE POTENTIAL FOR A FEW STRONG TO POSSIBLY SEVERE STORMS LATER THIS AFTERNOON AND EARLY EVENING... WITH STRONG TO POTENTIALLY DAMAGING WINDS BEING THE MAIN CONCERN FOR LATER TODAY. NOTHING WIDESPREAD IS EXPECTED... JUST CANNOT RULE OUT THIS POSSIBILITY AS AFTERNOON SBCAPE VALUES CLIMB BACK INTO THE 3000-4000 J/KG RANGE...ESPECIALLY ACROSS CENTRAL GA. AS FOR THE HEAT... AREA TEMPS ARE EXPECTED TO PUSH WELL INTO THE 90S AGAIN TODAY FOR MOST AREAS... ESPECIALLY ACROSS CENTRAL GA WHERE NEAR 100 DEGREE TEMPS WILL ONCE AGAIN BE FELT DURING MAX DAYTIME HEATING. THIS WILL PUSH HEAT INDEX VALUES NEAR OR ABOVE THE CRITICAL 105 DEGREE MARK FOR AREAS GENERALLY ALONG AND SOUTH OF LUMPKIN TO FORSYTH TO ATHENS LINE WHERE A HEAT ADVISORY IS CURRENTLY IN EFFECT. SEE NO REASON TO CHANGE THE ADVISORY AS CURRENTLY POSTED. THE BIG CHANGE WILL COME ON SUNDAY AS A COLD FRONT PUSHES DOWN FROM THE NORTHEAST AND PUSHES SOUTH OF COLUMBUS AND MACON BY SUNDAY EVENING. THIS WILL SPREAD CLOUDS AND INCREASING RAIN CHANCES ACROSS THE AREA... BUT MORE IMPORTANTLY... BRING MUCH RELIEF FROM THE HEAT AS SUNDAY AFTERNOON TEMPS STRUGGLE TO GET INTO THE 90S FOR MOST AREAS. ALTHOUGH SUSPECT THE CONVECTION ON SUNDAY WILL LIKELY BE MOSTLY SHOWERS... MODELS CONTINUE TO SHOW 1000-2000 J/KG OF CAPE AHEAD AND BEHIND THE FRONT SUNDAY AFTERNOON... SO WILL CONTINUE TO WORD FOR A CHANCE OF THUNDERSTORMS AS WELL. HOWEVER... NOTHING SEVERE IS EXPECTED AT THIS TIME. 39 LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... /ISSUED AT 347 AM EDT SAT AUG 23 2014/ UPPER RIDGE CONTINUES TO DOMINATE AT THE BEGINNING OF THE EXTENDED...WHILE SFC RIDGE BUILDS ACROSS THE MID ATLANTIC AND DOWN THE APPALACHIANS. WITH THE PSEUDO WEDGE BUILDING IN...WINDS BECOME EASTERLY AND CLOUD COVERAGE REMAINS BKN AT LEAST INITIALLY. CLOUD COVERAGE DOES HELP TO KEEP TEMPS ON THE COOLER SIDE ON MONDAY. DRIER AIR MOVES IN FOR THE FIRST HALF OF THE WEEK /BEHIND THE BACKDOOR FRONT/. WITH THIS...DO NOT HAVE MOISTURE AROUND FOR MUCH IN TERMS OF PRECIP AND THUS HAVE LIMITED POPS TO NO MENTION OR SLIGHT CHANCE. DIFFERENCES EXIST BETWEEN THE GFS AND ECMWF IN THE SECOND HALF THE OF THE EXTENDED. GFS BRINGS A COLD FRONT INTO THE AREA ON FRIDAY...WHILE THE ECMWF KEEPS AN UPPER RIDGE ACROSS THE SOUTHEAST. HAVE TENDED MORE TOWARDS THE GFS AND SHOWN AN INCREASE IN CLOUDS/PRECIP FOR FRIDAY ASSOCIATED WITH THE FRONT. DIFFERENCES ALSO EXIST STILL WITH HOW THE MODELS ARE HANDLING THE POTENTIAL TROPICAL SYSTEM NEXT WEEK. GFS REMAINS FURTHER WEST AND SLOWER WHILE THE ECMWF IS FURTHER EAST /ALTHOUGH LATEST RUN IS WEST OF PREVIOUS RUN/ AND FASTER. NEITHER 00Z SOLUTION BRINGS IMPACTS TO THE CWA...BUT REGARDLESS...STILL FAR OUT IN THE FORECAST AND ITS SOMETHING THAT NEEDS TO BE WATCHED AS WE HEAD INTO NEXT WEEK. 11 AVIATION... 12Z UPDATE... VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD DESPITE A BIG CHANGE IN OVERALL WEATHER PATTERN. HIGH PRESSURE WEAKENS ITS GRIP TODAY... ALLOWING SLIGHTLY BETTER CHANCE FOR SCT AFTERNOON THUNDERSTORMS. THEN A BACKDOOR COLD FRONT SWEEPS ACROSS THE AREA EARLY ON SUN... BRINGING MID LEVEL CIGS AND SCT TO NUMEROUS SHOWERS WITH SOME EMBEDDED THUNDERSTORMS TO THE AREA EARLY ON SUN. WILL SHOW TEMPO -TSRA 19-23Z TODAY... THEN PROB30 -SHRA 12-18Z SUN WITH THE FRONT. CURRENT NW WINDS PERSIST TODAY AROUND 8-11KTS... THEN SHIFT NE AROUND 08-10Z SUN WITH SPEEDS AROUND 10-12KTS ON SUN. //ATL CONFIDENCE...12Z UPDATE... MEDIUM ON ALL ELEMENTS. 39 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 97 73 88 70 / 30 30 60 30 ATLANTA 93 75 90 72 / 30 20 60 40 BLAIRSVILLE 88 69 83 67 / 30 30 60 40 CARTERSVILLE 94 71 89 72 / 30 20 60 40 COLUMBUS 98 75 94 75 / 20 20 60 40 GAINESVILLE 94 73 87 71 / 30 30 60 40 MACON 99 73 93 72 / 20 20 60 40 ROME 95 71 91 73 / 30 20 60 40 PEACHTREE CITY 94 71 90 72 / 20 20 60 40 VIDALIA 99 75 94 74 / 20 20 60 40 && .FFC WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING ZONES: BALDWIN...BIBB...BLECKLEY...CLARKE...CRAWFORD...CRISP... DODGE...DOOLY...EMANUEL...GLASCOCK...GREENE...HANCOCK... HOUSTON...JASPER...JEFFERSON...JOHNSON...JONES...LAURENS... MACON...MONROE...MONTGOMERY...MORGAN...OCONEE...OGLETHORPE... PEACH...PULASKI...PUTNAM...SCHLEY...STEWART...SUMTER... TALIAFERRO...TAYLOR...TELFAIR...TOOMBS...TREUTLEN...TWIGGS... WARREN...WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKES... WILKINSON. && $$ SHORT TERM... AVIATION...
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
947 AM EDT SAT AUG 23 2014 .UPDATE... HIGH PRESSURE ALOFT AND AT THE SURFACE WILL CONTINUE ACROSS THE REGION TODAY. LATEST RUNS OF THE HRRR KEEP CONVECTION VERY SPARSE ACROSS THE CWFA TODAY...AND LOW END SCT/ISOLD POPS STILL LOOK GOOD. DO THINK ANY CONVECTIVE ACTIVITY THAT DOES DEVELOP WILL BE TERRAIN BASED...OR DEPENDENT UPON ANY MESOSCALE BOUNDARIES. MODIFIED SOUNDING DOES SHOW SOME VERY GOOD SURFACE INSTABILITY PRESENT. SOUNDING ALSO ALSO SHOWS PLENTY OF DRY AIR ALOFT. SO...IF THUNDERSTORMS ARE ABLE TO DEVELOP...THEY WOULD LIKELY BE ABLE TO PRODUCE GUSTY WINDS AND FREQUENT LIGHTNING STRIKES. ISOLD SEVERE IS POSSIBLE...BUT THE POTENTIAL REMAINS LOW DUE TO VERY LITTLE CONVECTIVE COVERAGE EXPECTED. && .PREV DISCUSSION... /ISSUED 721 AM EDT SAT AUG 23 2014/ SHORT TERM /TODAY THROUGH SUNDAY/... /ISSUED AT 347 AM EDT SAT AUG 23 2014/ BIG CHANGES ON TAP THROUGH THE SHORT TERM PERIOD AS MODELS CONTINUE TO SHOW JUST ONE MORE HOT DAY BEFORE A WELCOMED BACK DOOR COLD FRONT SWEEPS ACROSS THE AREA ON SUNDAY. FOR TODAY... THE DOMINATING UPPER RIDGE BEGINS TO RETREAT WESTWARD AS A SERIES OF DISTURBANCES TRACK DOWN THE EASTERN PERIPHERY AND ACROSS THE STATE DURING THE AFTERNOON AND OVERNIGHT HOURS. THIS WILL WARRANT SHOWING A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE NORTH AND EAST CENTRAL PORTIONS OF THE FORECAST AREA TODAY... AND HOLDING ONTO A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS FOR ALL AREAS TONIGHT. THE CONTINUED HEAT AND STRONG INSTABILITY COUPLED WITH SOME UPPER SUPPORT SUGGEST THE POTENTIAL FOR A FEW STRONG TO POSSIBLY SEVERE STORMS LATER THIS AFTERNOON AND EARLY EVENING... WITH STRONG TO POTENTIALLY DAMAGING WINDS BEING THE MAIN CONCERN FOR LATER TODAY. NOTHING WIDESPREAD IS EXPECTED... JUST CANNOT RULE OUT THIS POSSIBILITY AS AFTERNOON SBCAPE VALUES CLIMB BACK INTO THE 3000-4000 J/KG RANGE...ESPECIALLY ACROSS CENTRAL GA. AS FOR THE HEAT... AREA TEMPS ARE EXPECTED TO PUSH WELL INTO THE 90S AGAIN TODAY FOR MOST AREAS... ESPECIALLY ACROSS CENTRAL GA WHERE NEAR 100 DEGREE TEMPS WILL ONCE AGAIN BE FELT DURING MAX DAYTIME HEATING. THIS WILL PUSH HEAT INDEX VALUES NEAR OR ABOVE THE CRITICAL 105 DEGREE MARK FOR AREAS GENERALLY ALONG AND SOUTH OF LUMPKIN TO FORSYTH TO ATHENS LINE WHERE A HEAT ADVISORY IS CURRENTLY IN EFFECT. SEE NO REASON TO CHANGE THE ADVISORY AS CURRENTLY POSTED. THE BIG CHANGE WILL COME ON SUNDAY AS A COLD FRONT PUSHES DOWN FROM THE NORTHEAST AND PUSHES SOUTH OF COLUMBUS AND MACON BY SUNDAY EVENING. THIS WILL SPREAD CLOUDS AND INCREASING RAIN CHANCES ACROSS THE AREA... BUT MORE IMPORTANTLY... BRING MUCH RELIEF FROM THE HEAT AS SUNDAY AFTERNOON TEMPS STRUGGLE TO GET INTO THE 90S FOR MOST AREAS. ALTHOUGH SUSPECT THE CONVECTION ON SUNDAY WILL LIKELY BE MOSTLY SHOWERS... MODELS CONTINUE TO SHOW 1000-2000 J/KG OF CAPE AHEAD AND BEHIND THE FRONT SUNDAY AFTERNOON... SO WILL CONTINUE TO WORD FOR A CHANCE OF THUNDERSTORMS AS WELL. HOWEVER... NOTHING SEVERE IS EXPECTED AT THIS TIME. 39 LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... /ISSUED AT 347 AM EDT SAT AUG 23 2014/ UPPER RIDGE CONTINUES TO DOMINATE AT THE BEGINNING OF THE EXTENDED...WHILE SFC RIDGE BUILDS ACROSS THE MID ATLANTIC AND DOWN THE APPALACHIANS. WITH THE PSEUDO WEDGE BUILDING IN...WINDS BECOME EASTERLY AND CLOUD COVERAGE REMAINS BKN AT LEAST INITIALLY. CLOUD COVERAGE DOES HELP TO KEEP TEMPS ON THE COOLER SIDE ON MONDAY. DRIER AIR MOVES IN FOR THE FIRST HALF OF THE WEEK /BEHIND THE BACKDOOR FRONT/. WITH THIS...DO NOT HAVE MOISTURE AROUND FOR MUCH IN TERMS OF PRECIP AND THUS HAVE LIMITED POPS TO NO MENTION OR SLIGHT CHANCE. DIFFERENCES EXIST BETWEEN THE GFS AND ECMWF IN THE SECOND HALF THE OF THE EXTENDED. GFS BRINGS A COLD FRONT INTO THE AREA ON FRIDAY...WHILE THE ECMWF KEEPS AN UPPER RIDGE ACROSS THE SOUTHEAST. HAVE TENDED MORE TOWARDS THE GFS AND SHOWN AN INCREASE IN CLOUDS/PRECIP FOR FRIDAY ASSOCIATED WITH THE FRONT. DIFFERENCES ALSO EXIST STILL WITH HOW THE MODELS ARE HANDLING THE POTENTIAL TROPICAL SYSTEM NEXT WEEK. GFS REMAINS FURTHER WEST AND SLOWER WHILE THE ECMWF IS FURTHER EAST /ALTHOUGH LATEST RUN IS WEST OF PREVIOUS RUN/ AND FASTER. NEITHER 00Z SOLUTION BRINGS IMPACTS TO THE CWA...BUT REGARDLESS...STILL FAR OUT IN THE FORECAST AND ITS SOMETHING THAT NEEDS TO BE WATCHED AS WE HEAD INTO NEXT WEEK. 11 AVIATION... 12Z UPDATE... VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD DESPITE A BIG CHANGE IN OVERALL WEATHER PATTERN. HIGH PRESSURE WEAKENS ITS GRIP TODAY... ALLOWING SLIGHTLY BETTER CHANCE FOR SCT AFTERNOON THUNDERSTORMS. THEN A BACKDOOR COLD FRONT SWEEPS ACROSS THE AREA EARLY ON SUN... BRINGING MID LEVEL CIGS AND SCT TO NUMEROUS SHOWERS WITH SOME EMBEDDED THUNDERSTORMS TO THE AREA EARLY ON SUN. WILL SHOW TEMPO -TSRA 19-23Z TODAY... THEN PROB30 -SHRA 12-18Z SUN WITH THE FRONT. CURRENT NW WINDS PERSIST TODAY AROUND 8-11KTS... THEN SHIFT NE AROUND 08-10Z SUN WITH SPEEDS AROUND 10-12KTS ON SUN. //ATL CONFIDENCE...12Z UPDATE... MEDIUM ON ALL ELEMENTS. 39 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 97 73 88 70 / 30 30 60 30 ATLANTA 93 75 90 72 / 30 20 60 40 BLAIRSVILLE 88 69 83 67 / 30 30 60 40 CARTERSVILLE 94 71 89 72 / 30 20 60 40 COLUMBUS 98 75 94 75 / 20 20 60 40 GAINESVILLE 94 73 87 71 / 30 30 60 40 MACON 99 73 93 72 / 20 20 60 40 ROME 95 71 91 73 / 30 20 60 40 PEACHTREE CITY 94 71 90 72 / 20 20 60 40 VIDALIA 99 75 94 74 / 20 20 60 40 && .FFC WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING ZONES: BALDWIN...BIBB...BLECKLEY...CLARKE...CRAWFORD...CRISP... DODGE...DOOLY...EMANUEL...GLASCOCK...GREENE...HANCOCK... HOUSTON...JASPER...JEFFERSON...JOHNSON...JONES...LAURENS... MACON...MONROE...MONTGOMERY...MORGAN...OCONEE...OGLETHORPE... PEACH...PULASKI...PUTNAM...SCHLEY...STEWART...SUMTER... TALIAFERRO...TAYLOR...TELFAIR...TOOMBS...TREUTLEN...TWIGGS... WARREN...WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKES... WILKINSON. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
155 AM EDT SAT AUG 23 2014 .SYNOPSIS... A BACK DOOR COLD FRONT WILL MOVE INTO AND THROUGH THE NORTHERN AND CENTRAL MIDLANDS SATURDAY...AND THEN SHIFT TOWARDS THE CSRA SUNDAY. THIS WILL LEAD TO A CHANCE OF THUNDERSTORMS ALONG AND AHEAD OF THE FRONT...WITH TEMPERATURES RETURNING TO MORE NORMAL LEVELS BEHIND IT. THE FRONT WILL LINGER SOUTH OF THE CSRA EARLY TO MID NEXT WEEK...LEADING TO GENERALLY FAIR WEATHER WITH NEAR NORMAL TEMPERATURES. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... WV LOOP SHOWS WEAK S/W MOVING SOUTHEASTWARD TOWARD THE NRN CWA/PEE DEE REGION. MODELS ALSO SHOW THIS S/W MOVING SOUTH/SOUTHEAST OVERNIGHT. 88D REGIONAL COMPOSITE SHOWS A CLUSTER OF SHRA/TSRA JUST NORTH OF CLT. HRRR INDICATES THAT SOME OF THIS ACTIVITY COULD SLIP INTO THE NRN MIDLANDS/PEE DEE OVER THE NEXT FEW HOURS. HAVE INCREASED POPS SLIGHTLY ACROSS LANCASTER...CHESTERFIELD...NRN KERSHAW AND NERN LEE COUNTY. OVERNIGHT LOWS IN THE LOW/MID 70S LOOK ON TRACK. OTHERWISE...SURFACE LOW PRESSURE ALONG THE VA COAST IS FORECAST TO MOVE SOUTHWARD OVERNIGHT INTO EASTERN NC. THIS WILL ALLOW A BACKDOOR COLD FRONT TO APPROACH THE NORTHERN MIDLANDS/PEE DEE AROUND DAYBREAK SATURDAY. KEPT OVERNIGHT LOWS NEAR CONSENSUS IN THE LOWER AND MIDDLE 70S. && .SHORT TERM /7 AM THIS MORNING THROUGH 6 PM SUNDAY/... MAIN ISSUE FOR SATURDAY AND INTO SUNDAY IS TIMING OF APPROACHING BACK DOOR FRONT. THINK PRE-FRONTAL TROUGH SETS UP ACROSS SOUTHERN CWA SATURDAY WITH FRONT IN EASTERN NORTH CAROLINA SHIFTING SOUTHWEST DURING SATURDAY EVENING. MOS POP GUIDANCE LOW BUT SREF AND MODEL QPF SUGGEST SCATTERED SHOWERS AND THUNDERSTORMS AHEAD AND ALONG FRONT AS AIR MASS MODERATELY UNSTABLE AND MOISTURE INCREASING...PRECIPITABLE WATER MAY RISE TO AROUND 2 INCHES. WARM MAX TEMPS STILL POSSIBLE SAT AHEAD OF THE FRONT...WITH WARMEST TEMPS FAVORING THE CSRA WHERE TEMPS COULD REACH 100 AGAIN. WITH NAM BEING SLIGHTLY FASTER THAN GFS WITH THE BACK DOOR FRONT...THE NAM MOS IS SLIGHTLY COOLER THAN THE GFS MOS FOR SAT MAX TEMP...ESPECIALLY NORTH AND CENTRAL. EVEN IF TEMPS NEAR 100 REACHED AGAIN SAT...GUIDANCE STILL SUGGESTS DEWPOINTS LOW ENOUGH TO PRECLUDE HEAT INDEX VALUES FROM REACHING OUR HEAT ADVISORY CRITERIA OF 110F. FRONT EXPECTED TO SHIFT SW THRU THE FA SAT NIGHT THRU SUN NIGHT. EXPECT CHANCE POPS NEAR AND JUST AHEAD OF THE FRONT...WITH COOLING TEMPS ALONG AND NORTH OF IT. SO...POPS SUN AFTERNOON FAVORING THE CSRA WHERE INSTABILITY/LOW LEVEL CONVERGENCE STRONGER. HIGH TEMPS SUNDAY SHOULD BE NOTICEABLY LESS BEHIND THE FRONT. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... MODELS IN GOOD AGREEMENT WITH MOVING THE FRONT SOUTH OF THE SAVANNAH RIVER WITH UPPER LEVEL RIDGE BUILDING IN FOR THE WEEK. WITH COOLER DRY AIR SETTLING IN WILL BRING SLIGHTLY BELOW NORMAL TEMPS. EXPECT MAX TEMPS 85 TO 90 EARLY TO MID WEEK RISING BACK INTO THE LOWER 90S LATER IN THE WEEK. OVERNIGHT MINS WILL BE 65 TO 70 RISING INTO THE LOWER 70S LATER IN THE WEEK. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS EXPECTED THROUGH THE PERIOD. SCATTERED CONVECTIVE DEBRIS FROM THUNDERSTORMS ALONG THE NC/SC LINE CONTINUE MOVING INTO THE TAF SITES. WITH THE WEAK FRONTAL BOUNDARY SLOWLY MOVING SOUTHWARD EXPECT INCREASING MID AND UPPER LEVEL CLOUDS OVERNIGHT...WHICH WILL WORK TO PREVENT FOG DEVELOPMENT. THE FRONT WILL REMAIN NORTH OF THE TAF SITES THROUGH THE PERIOD...WITH ISOLATED TO SCATTERED CONVECTION POSSIBLE DURING THE AFTERNOON AND EVENING HOURS. CONFIDENCE REMAINS LOW IN REGARD TO COVERAGE SO HAVE NOT INCLUDED MENTION OF CONVECTION IN TAFS ATTM. BEST CHANCE FOR CONVECTION WILL BE CAE/CUB AND NORTHWARD. WINDS THROUGH THE PERIOD WILL BE NORTHERLY AT 7 KNOTS OR LESS. EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE NIGHT AND EARLY MORNING FOG SUNDAY AND MONDAY. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS SUNDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS POCATELLO ID
150 PM MDT SAT AUG 23 2014 .SHORT TERM...TONIGHT THROUGH TUESDAY. THE LATEST SATELLITE IMAGERY WAS SHOWING A LOW PRESSURE SYSTEM OVERHEAD WITH SEVERAL WELL DEFINED VORT FEATURES EMBEDDED IN THE FLOW. CURRENT RADAR TRENDS ARE SHOWING A RAPID INCREASE IN SHOWER ACTIVITY EARLY THIS MORNING AND CURRENTLY ANTICIPATE THIS CONTINUE AND BECOME MORE LINEARLY FOCUSED THROUGH THE AFTERNOON AS ONE OF THE EMBEDDED VORT FEATURES PLUNGES SOUTH THROUGH THE SNAKE RIVER PLAIN AND THE SURFACE WINDS BEGIN TO FORM A CONVERGENCE AREA WITH THUNDERSTORMS ACROSS THE UPPER VALLEY THAT DRIFTS SOUTH LATE THIS AFTERNOON BEFORE DISSIPATING LATER THIS EVENING AS THE UPPER LOW BEGINS TO LIFT NE INTO SRN MONTANA. ANTICIPATING A BRIEF BRAKE IN THE ACTION SUNDAY MORNING BEFORE THE NEXT PAC THROUGH DIGS INTO THE NW STATES SUNDAY AFTERNOON FURTHER WEST THAN PREVIOUS PROGS SPINNING UP A SHALLOW CLOSED LOW OVER THE NRN GREAT BASIN SUNDAY AFTERNOON/NIGHT WITH AN INCREASE IN SHOWER ACTIVITY WHICH LINGERS THROUGH MONDAY NIGHT/TUESDAY AS THE LOW SLOWLY FILLS AND GRADUALLY SWINGS EAST ALONG THE NEVADA/UTAH BORDER BEFORE EXITING EAST OF THE REGION TUESDAY EVENING. .LONG TERM...TUESDAY NIGHT THROUGH NEXT SATURDAY. DRIER AND WARMER CONDITIONS DEVELOP ACROSS SRN IDAHO WEDNESDAY THROUGH FRIDAY AS A TRANSIENT UPPER RIDGE MIGRATES EAST ACROSS THE AREA AHEAD OF THE NEXT APPROACHING PAC STORM SYSTEM. THE 12Z GFS CONTINUES TO TAP INTO THE REMNANTS OF HURRICANE MARIE AS IT LIFTS NE OUT OF THE SUB-TROPICAL ERN PACIFIC WATERS OFF THE MEXICAN COAST TO A POSITION WELL OFF THE CALIFORNIA COAST FRIDAY AHEAD OF THE INCOMING TROUGH. AS THE TROUGH MOVES INLAND SATURDAY...THE GFS BEGINS TO INTERACT WITH THE SUB-TROPICAL MOISTURE PRODUCING WIDESPREAD SHOWER ACTIVITY ACROSS IDAHO. THE 12Z ECMWF TAKES MARIE ON A MORE NWRLY TRAJECTORY PREVENTING THE INCOMING TROUGH FROM TAPPING INTO THE MOIST SUB-TROPICAL SYSTEM WITH DRIER CONSEQUENCES. WE WILL CONTINUE TO MONITOR THE MODEL TRENDS FOR ANY CHANGE IN EITHER MODEL. HUSTON && .AVIATION...UPPER LOW IS SLOWLY DRIFTING ACROSS SOUTHEAST IDAHO THIS AFTERNOON. ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE IN THE COLD CORE REGION WITH MOST OF THE STRATIFORM PRECIP WRAPPING AROUND THE LOW INTO THE SALMON/CHALLIS AREA. STARTING TO SEE CEILINGS AT KIDA LIFT FROM IFR TO MVFR...AND SHOULD SCATTER OUT IN THE EARLY AFTERNOON. HRRR SIGNALS INCREASING SHOWER ACTIVITY AROUND MID-AFTERNOON AND INTO THE EVENING AS LOW MOVES INTO THE YELLOWSTONE AREA. FORECAST SOUNDINGS FAVORING 6000 FT TO 10000 FT CEILINGS OVERNIGHT INTO TOMORROW. HINSBERGER && .FIRE WEATHER...A LITTLE LESS COVERAGE OF SHOWERS AND THUNDERSTORMS TODAY AS UPPER LOW SLOWLY DRIFTS ACROSS SOUTHEAST IDAHO TODAY. HEAVIER PRECIP IS BEING WRAPPED AROUND THE LOW INTO LEMHI COUNTY. DRIER WEATHER IS EXPECTED SUNDAY AS INFLUENCE OF LOW WANES...BUT MODELS ARE PROJECTING ANOTHER UPPER LOW TO DROP INTO OR/ID SUNDAY NIGHT. IMPULSES OF ENERGY AROUND THE LOW WILL BRING MORE SHOWERS AND THUNDERSTORMS TO THE AREA DURING THE DAY MONDAY...AND MAY LINGER INTO TUESDAY MORNING. UPPER RIDGING WILL BRING DRIER WEATHER TO THE REGION LATER ON TUESDAY AND SHOULD LAST THROUGH FRIDAY. A PACIFIC TROUGH WILL APPROACH THE WEST ON FRIDAY. REMNANTS OF HURRICANE MARIE MAY BE POSITIONED TO CONTRIBUTE ITS TROPICAL MOISTURE THOUGH THERE IS STILL SOME UNCERTAINTY WITH ITS TRACK IN RELATION TO THE PACIFIC TROUGH...BUT SIGNS POINT TO ANOTHER WET WEEKEND. HINSBERGER && .PIH WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
329 PM CDT SAT AUG 23 2014 .DISCUSSION... 326 PM CDT A PERSISTENT UPPER RIDGE THAT HAS BEEN SITTING OVER THE MIDWEST WILL GRADUALLY FLATTEN AND BE PUSHED TO THE SOUTH AND EAST OVER THE NEXT FEW DAYS...BUT NOT UNTIL THIS COMING THURSDAY OR FRIDAY WILL IT AND ITS SURFACE MANIFESTATION BE PUSHED FAR ENOUGH AWAY TO ALLOW A SURGE OF COOLER AND DRIER AIR INTO THE LOCAL AREA. UNTIL MIDWEEK THE WARM AND HUMID AIRMASS WILL REMAIN IN PLACE...SUPPORTING ONGOING CHANCES OF SHOWERS AND THUNDERSTORMS...WITH HEAT INDICIES ON MONDAY APPROACHING THE LOCAL HEAT ADVISORY CRITERIA OF 105F. POTENT SHORTWAVES LIFTING THROUGH THE TOP OF THE RIDGE TODAY HAVE SUPPORTED A BROAD CLUSTER OF THUNDERSTORMS WITH HEAVY RAIN. MODELS ARE IN REASONABLE AGREEMENT IN SHOWING SIMILAR BUT SOMEWHAT WEAKER WAVES LIFTING THROUGH AGAIN TOMORROW...THOUGH THE FOCUS IS A BIT FARTHER WEST. ALSO...MORE PRONOUNCED WARM ADVECTION AROUND THE 850MB LEVEL LOCALLY IS EXPECTED TO INHIBIT CONVECTIVE DEVELOPMENT COMPARED TO WHAT WE SAW TODAY...AND THE INCREASED CLOUDINESS FROM THE SHORTWAVES SHOULD ALSO SERVE TO LIMIT THE DEGREE OF AFTERNOON SURFACE HEATING. AS A WEAK SURFACE TROUGH APPROACHES SLOWLY FROM THE NORTHWEST...TSRA CHANCES CREEP BACK UP AGAIN MONDAY AND TUESDAY ALONG WITH...AND BECAUSE OF...MORE PRONOUNCED LOW LEVEL HEATING WITH SOUTH TO SOUTHWEST WINDS SUPPORTING BETTER MIXING AND A WEAKER CAP ALOFT. MONDAY LOOKS TO BE WARMER THAN EITHER SUNDAY OR TUESDAY...AND AMPLE MOISTURE WILL SUPPORT HEAT INDICIES BETWEEN 100 AND 105...NEAR THE CRITERIA FOR A HEAT ADVISORY. IT IS A BIT EARLY TO HOIST A HEADLINE BUT THIS WILL CONTINUE TO BE MONITORED. BY WEDNESDAY THE TROUGH JUST TO OUR NORTHWEST WILL HAVE EVOLVED TO A WARM FRONT ASSOCIATED WITH A LOW OVER THE PLAINS. THIS LOW THEN LIFTS ALONG THIS BOUNDARY AND SETTLES OVER THE LOCAL AREA ON THURSDAY BEFORE CONTINUING OFF TO THE EAST ON FRIDAY. HIGH TEMPERATURES BOTH WEDNESDAY AND THURSDAY COULD BE TRICKY DEPENDING ON WHERE THE SURFACE BOUNDARIES SET UP...BUT INCREASED CLOUDINESS AND ONGOING TSRA CHANCES SHOULD KEEP THOSE DAYS COOLER THAN MONDAY AND TUESDAY. THE MORE SIGNIFICANT CHANGE OF AIRMASS WILL THEN BE IN PLACE ACROSS THE ENTIRE AREA BY FRIDAY AND SATURDAY...THOUGH THE ECMWF IS A BIT SLOWER THAN THE GFS IN PUSHING THIS BOUNDARY THROUGH. LENNING && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * RAIN WITH THE CHANCE FOR A WIDELY SCATTERED LIGHTNING STRIKE THROUGH 21Z...THEN A SMALL CHANCE FOR ISOLATED SHRA/TSRA THROUGH THIS EVE. * EAST-NORTHEAST WINDS EASING IN SPEED THROUGH LATE AFTERNOON BUT REMAINING EASTERLY IN DIRECTION. * POTENTIAL FOR IFR CIGS AND/OR VISIBILITY TONIGHT INTO SUNDAY MORNING. * LAKE BREEZE TURNING WINDS EASTERLY AROUND OR POSSIBLY ABOVE 10 KT SUNDAY. //DISCUSSION...UPDATED 20Z... LINE OF STORMS HAS MOVED EAST-SOUTHEAST OF ORD AND MDW WITH STRATIFORM RAIN TO CONTINUE THROUGH 21Z. CLOUD-TO-GROUND LIGHTNING DENSITY IN THIS HAS BEEN VERY SPARSE SO HAVE OPTED NOT TO MENTION TSRA BEYOND 20Z. EASTERLY WINDS HAVE OCCASIONALLY GUSTED ON THE BACKSIDE OF THE STORMS AND SHOULD SEE A SLOW EASE IN SPEED. THE RAINFALL ALONG WITH DIMINISHING WIND SPEED GOING TO THIS EVE...LIKELY WILL LEAD TO BETTER POTENTIAL FOR FOG AND/OR STRATUS. PREV DISCUSSION...UPDATED 18Z... AREA OF SHOWERS AND STORMS CONTINUES TO MOVE EASTWARD WITH A SLOW WANING TREND...ESPECIALLY IN PART OF THE SEGMENT JUST UPSTREAM OF ORD AND MDW. WHILE THAT IS THE CASE...INCREASED CONVERGENCE BETWEEN THE OUTFLOW AND THE LAKE BREEZE IN UNCAPPED AIR WILL LIKELY SPARK MORE STORMS. THIS ALSO COULD EXTEND THE TSRA TIMING. SO FEEL COMFORTABLE WITH THE TSRA STILL INDICATED IN THE CHICAGOLAND TAFS. STRATIFORM RAIN BEHIND THIS WILL LIKELY BE ACCOMPANIED WITH MVFR CONDITIONS. SCATTERED SHOWERS AND STORMS ARE POSSIBLE BEHIND THIS DURING THE LATTER HALF OF THE AFTERNOON INTO THE EVENING IN THE CONTINUED MOISTURE RICH AIR MASS. THE WIND DIRECTION WILL LIKELY TURN SOUTHWEST AS THE STORMS PASS...AS ALL OBSERVATIONS SITES HAVE INDICATED THAT UPSTREAM AND RADAR SHOW WELL-DEFINED OUTFLOW. THE SPEED OF THE OUTFLOW HAS SLOWED SOME...SO THE DEGREE OF GUSTS AT CHICAGOLAND TAF SITES IS EXPECTED TO BE LESS THAN 30 KT. THE WIND DIRECTION BEHIND THE INITIAL PUSH OF STORMS MAY BECOME VARIABLE...BUT IS ANTICIPATED TO TURN EAST OR SOUTHEAST BASED ON THE SYNOPTIC FLOW AND CLIMATOLOGY FOR POST-THUNDERSTORM WINDS AT ORD. THE MOISTURE IN THE LOW-LEVELS AIDED BY RAIN EARLY THIS AFTERNOON WILL SET THE STAGE ONCE AGAIN FOR FOG AND LOW CIGS TONIGHT...HOWEVER THE COVERAGE OF THIS IS DIFFICULT TO DETERMINE AT THIS TIME. A LAKE BREEZE LOOKS LIKELY ON SUNDAY AFTERNOON INTO NORTHEAST ILLINOIS THAT WILL PROBABLY REACH BOTH ORD AND MDW. //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH IN RAIN END TIME. LOW IN WHETHER ANYMORE SHRA/TSRA WILL OCCUR THROUGH THIS EVE. * MEDIUM IN WIND DIRECTION AND SPEED THROUGH EARLY THIS EVE. * MEDIUM IN SOME FORM OF IFR RESTRICTION LATE TONIGHT INTO EARLY SUNDAY MORNING. LOW ON WHETHER FOG AND/OR CIG. //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MTF && .MARINE... 153 PM CDT RELATIVELY LIGHT WINDS ARE IN PLACE THIS AFTERNOON AS A WEAK PRESSURE GRADIENT IS IN PLACE ACROSS THE REGION. WINDS WILL BEGIN TO FRESHEN UP SLIGHTLY TONIGHT AND VEER TO THE SOUTHEAST AS BROAD AREA OF LOW PRESSURE OVER THE PLAINS BEGINS TO CONSOLIDATE AND DEEPEN AS IT LIFTS TOWARDS THE CANADIAN PRAIRIES. THIS LOW WILL DRAG A WEAK COLD FRONT SOUTH ACROSS LAKE MICHIGAN LATE TUESDAY INTO WEDNESDAY WITH WINDS TURNING TO THE NORTH BEHIND THROUGH THE REMAINDER OF THE WEEK. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 319 PM CDT Sat Aug 23 2014 .SHORT TERM...(This evening through Sunday) ISSUED AT 319 PM CDT SAT AUG 23 2014 Southern flank of morning thunderstorm complex continues to impact the northeast KILX CWA around Champaign and Danville this afternoon, with only minimal development noted further southwest along the trailing outflow boundary. Models have once again handled the situation poorly, with the NAM/GFS being too aggressive with convective development and the HRRR keeping system too far north. Think storms will gradually push into Indiana over the next 3 to 4 hours, followed by only isolated convection across the eastern CWA early this evening. Once daytime instability wanes, dry conditions are expected overnight. With clearing skies and light winds, fog will likely develop late tonight into Sunday morning. Forecast soundings and numeric guidance both suggest at least some restriction to visibilities, and based on what happened last night, think its prudent to carry patchy fog late tonight. Upper ridge axis will continue to control the weather across central Illinois on Sunday, providing hot and mainly dry conditions. Some models are hinting that widely scattered convection may fire along the Indiana border by afternoon, but think this is a bit overdone. Will only maintain slight chance PoPs across the far southeast, with dry weather elsewhere. High temperatures will reach the lower 90s, resulting in heat index values of 100 to 105 degrees. && .LONG TERM...(Sunday night through Saturday) ISSUED AT 319 PM CDT SAT AUG 23 2014 Medium range models are generally in good agreement for the first few days of next week, then they digress pretty rapidly for two reasons. First is the difference in solutions involving the speed and strength of the upper level trough expected to move from the Rockies to Midwest. This looks like it is being caused by the second main difference, which is a lot of uncertainty with the speed and motion of a pending tropical system in the western Atlantic. These tropical systems tend to back up the west-east progression of weather systems in the middle U.S. Thus, there is a greater than normal level of uncertainty with the forecast for Wednesday through the end of the week. In the nearer term period for Monday and Tuesday, it appears likely that the hot and humid conditions will continue. Monday could end up being one of the hottest days with highs from 93-95 in central IL and 91-93 in east/southeast IL. This will keep heat index values in the 105-108 range in much of central and southeast IL, so will keep the heat advisory going through Monday. Considered extending the advisory into Tuesday, but will hold off for now since there is some level of uncertainty as to the amount of increasing cloudiness during the day, which could keep temps down just a bit. The movement of a cold front, associated with aforementioned approaching upper level trough, will really depend on the east coast tropical system. The most likely scenario, which is not really handled very well by any model, is that the front will slowly approach - and may even get hung up in central IL for a day or two. Thus, will stick with a prolonged period of scattered showers/t-storms Wednesday into Friday. The cloudiness associated with this rain potential will keep temperatures down in the 80s, ending the stretch of hot weather. However, longer term trends indicate the possibility that we may see a return to very warm conditions for Labor Day weekend. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) ISSUED AT 1236 PM CDT SAT AUG 23 2014 Southern flank of storm complex tracking across northern Illinois is skirting along the I-74 corridor early this afternoon. Storms have already impacted KPIA with heavy rain and gusty winds up to around 25kt and will push through KBMI over the next hour. Still some question whether they will hold together and reach far enough south to impact KCMI, so have only gone with VCTS there. Elsewhere around the area, will maintain dry conditions through the afternoon. Once convection exits into Indiana, skies will gradually clear by this evening. Due to light winds and very high dewpoints, think fog will once again develop across the area overnight. Have therefore included restricted visbys down to between 2 and 4 miles between 09z and 14z. && .ILX WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY until 7 PM CDT Monday FOR ILZ042-047>054-056- 061>063-066>068-071>073. HEAT ADVISORY from Noon Sunday to 7 PM CDT Monday FOR ILZ036-040- 041. && $$ SHORT TERM...BARNES LONG TERM...MILLER AVIATION...BARNES
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
304 PM CDT SAT AUG 23 2014 .MESOSCALE DISCUSSION... 115 PM CDT LINE OF STORMS IS MOVING EAST INTO THE CHICAGOLAND AREA EARLY THIS AFTERNOON. WHILE THIS HAS SHOWN A GRADUAL WEAKENING TREND WITH LESS LIGHTNING...DESTABILIZATION ACROSS NORTHWEST IN...EASTERN IL...AND INTO THE SOUTH CHICAGO METRO THE PAST FEW HOURS SHOULD AID IN THE ACTIVITY TO AT LEAST PERSIST WITH HEAVY RAINFALL RATES. IN ADDITION...CONVERGENCE FROM THE SYSTEM OUTFLOW AND THE LAKE BREEZE HAS ALREADY FIRED A FEW ADDITIONAL CELLS AND THAT WILL LIKELY CONTINUE TO OCCUR IN SUBURBAN AREAS THROUGH 2-3 PM. THE AREA OF STORMS ALSO SHOULD FURTHER SLOW AS IT RUNS INTO THE MARINE LAYER. THIS MAY CAUSE HEAVY RAINFALL RATES TO PERSIST OVER THE SAME URBAN AREAS FOR A WHILE...INCLUDING THOSE THAT WERE HIT HARD LATE THURSDAY NIGHT. WILL BE MONITORING CLOSELY. SEVERE THREAT APPEARS MINIMAL...WITH MAINLY THE FAR SOUTHEAST CWA BEING THE ONE AREA THAT COULD SEE AN ISOLATED FLARE UP TO THAT LEVEL. NOW THAT AREAS HAVE BEEN RAIN COOLED...WILL ADJUST TEMPERATURES CONSIDERABLY DOWNWARD THE REST OF THE AFTERNOON. MTF && .DISCUSSION... 959 AM CDT THE FORECAST HAS BEEN UPDATED TO REFLECT GREATER CLOUD COVER AREAWIDE AND HIGHER POPS ACROSS MAINLY NORTH CENTRAL ILLINOIS DURING THE EARLY-MID AFTERNOON. A BROAD MESOSCALE CONVECTIVE SYSTEM WITH A LINE OF STORMS ON ITS FRONT EDGE IS CURRENTLY ADVANCING EAST OVER THE MISSISSIPPI RIVER AND FAR WESTERN ILLINOIS. THIS CONTINUES TO HOLD TOGETHER WELL WITH ONLY SUBTLE CLOUD TOP WARMING AND NO FADE IN LIGHTNING ACTIVITY OVER THE PAST COUPLE HOURS. THIS COMPLEX HAS BEEN ONGOING FOR OVER NINE HOURS SO NOT SURPRISED TO SEE THAT THE RADAR LOOP INDICATES THE LIKELY PRESENCE OF A CONVECTIVELY-INDUCED VORTICITY MAXIMUM /MCV/ IN FAR EASTERN IA. THIS WITH A COLD POOL IS HELPING TO USHER PUSH THE STORMS MORE EASTWARD THAN THE NORTHEAST MOVEMENT OF THE PARENT SHORTWAVE WOULD INDICATE. DESPITE WHAT SHOULD BE A GRADUAL FACE INTO THE EARLY AFTERNOON WITH THE UPPER SUPPORT MOVING NORTHEAST AND A DECAYING LOW-LEVEL JET PER PROFILERS...2.2 INCH PWAT AIR /99TH PERCENTILE/ AHEAD OF THE MCV WILL LIKELY SUPPORT SHOWERS AND SOME STORMS INTO NORTH CENTRAL ILLINOIS BETWEEN NOON AND 3 PM. STILL SEEING SOME EMBEDDED HOURLY PRECIP REPORTS OF A HALF TO ONE INCH WITH THIS...AND SOME OF THIS EFFICIENCY COULD CERTAINLY OCCUR ALONG AND WEST OF I-39 DURING THE EARLY AFTERNOON. UNDER THE INFLUENCE OF WEAK UPPER LEVEL FLOW...THE MCV IS FORECAST BY THE RAP AND NAM TO CONTINUE TO SLOW AS IT MOVES INTO NORTH CENTRAL IL. DESTABILIZATION AHEAD OF IT MAY SUPPORT ISOLATED OR SCATTERED SHOWERS/STORMS LATER THIS AFTERNOON FURTHER EAST TOWARD CHICAGO AND THE I-57 CORRIDOR INTO NORTHWEST INDIANA...BUT CONFIDENCE ON THIS IS LOW AS ANVIL SHIELD WILL INHIBIT THE RATE OF WARMTH...WITH MOST GUIDANCE INDICATING THE PRESENCE OF A CAP AND LOW-LEVEL FLOW OFF THE LAKE IN FAR NORTHEAST IL. MINOR TWEAKS MADE TO HOURLY TEMPERATURES AND DEW POINTS. MTF //PREV DISCUSSION... 327 AM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES/TIMING THROUGH THE PERIOD ALONG WITH HIGH TEMPERATURES/HEAT INDICES THROUGH MONDAY. AREAS OF FOG CONTINUE TO DEVELOP WITH VISIBILITIES DROPPING UNDER 1SM IN A FEW LOCATIONS. NOT EXPECTING WIDESPREAD DENSE FOG THIS MORNING BUT WILL NEED TO MONITOR OBS OVER THE NEXT FEW HOURS. THE FOG WILL LIFT THIS MORNING BUT WITH LITTLE CHANGE TO THE AIRMASS FOG WILL BE POSSIBLE AGAIN TONIGHT INTO SUNDAY MORNING. A FEW SHOWERS DEVELOPED ACROSS NORTHERN LAKE COUNTY IN NORTHEAST IL LATE FRIDAY EVENING AND PERSISTED FOR A FEW HOURS BEFORE DISSIPATING. OTHERWISE...CONVECTION HAS BEEN FOCUSED FURTHER WEST EARLY THIS MORNING IN THE VICINITY OF THE LOW LEVEL JET. SOME OF THIS ACTIVITY OVER EASTERN IA MAY ARRIVE ACROSS THE WESTERN CWA LATER THIS MORNING...LIKELY IN A DECAYING FORM. BUT OTHER THAN AN ISOLATED SHOWER...EXPECT THE NEXT SEVERAL HOURS TO BE MAINLY DRY. CONFIDENCE REGARDING THUNDERSTORM CHANCES THIS AFTERNOON INTO THIS EVENING IS LOW THOUGH THERE IS SOME CONSENSUS FOR DEVELOPMENT BY EARLY AFTERNOON ACROSS WESTERN/NORTHWEST IL FROM REMNANTS OF CONVECTION OVER EASTERN NEBRASKA/WESTERN IA. HOW FAR IT CONTINUES EAST OR NORTHEAST BEFORE WEAKENING IS ANOTHER UNCERTAINTY. MADE NO SIGNIFICANT CHANGES FOR TODAY MAINTAINING 30-40 POPS. TRENDS WILL NEED TO BE MONITORED THRU THE MORNING. DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES APPROACHING 2 INCHES WILL LEAD TO VERY HEAVY RAIN WITH ANY THUNDERSTORMS THAT DO DEVELOP AND POSSIBLY FLASH FLOODING...ESPECIALLY IF THE RAIN FALLS OVER HARDER HIT AREAS FROM FRIDAY MORNING. THE UPPER RIDGE THEN BUILDS ACROSS THE AREA TONIGHT AND SUNDAY AND PRECIP CHANCES LOOK BELOW MENTIONABLE FROM LATE TONIGHT THROUGH MONDAY MORNING. CAN/T COMPLETELY RULE OUT SOME ISOLATED ACTIVITY... IN PARTICULAR ON A LAKE BREEZE SUNDAY AFTERNOON. A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY WITH SOME DIFFERENCES AS TO HOW FAR SOUTH THIS BOUNDARY WILL SETTLE MONDAY AFTERNOON INTO MONDAY NIGHT. THIS WOULD LIKELY BE THE NEXT CHANCE OF THUNDERSTORMS WITH THE GEM/ECMWF BOTH PUSHING THE FRONT THROUGH MUCH OF THE CWA BY TUESDAY MORNING. THIS BOUNDARY THEN MEANDERS NEAR THE IL/WI BORDER INTO THURSDAY WITH THE POSSIBILITY OF A PROLONGED UNSETTLED PATTERN ACROSS THE AREA. CLOUD COVER/CONVECTION TODAY WILL LIKELY KEEP TEMPS IN THE 80S... THOUGH WITH THE URBAN AREAS STARTING FROM LOWER/MID 70S...ANY LONGER PERIOD OF SUNSHINE TODAY COULD ALLOW A FEW PLACES TO TAG 90. TEMPS WILL WARM A FEW DEGREES SUNDAY BUT SOUTHEASTERLY WINDS WILL KEEP THE LAKESHORE COOLER. MONDAY LOOKS TO BE THE BEST CHANCE FOR TEMPS INTO THE LOWER 90S CWA WIDE BUT WILL BE DEPENDENT ON CLOUD COVER AND TIMING/ARRIVAL OF ANY PRECIP. DEWPOINTS MAY LOWER A FEW DEGREES...BACK INTO THE MID/UPPER 60S ACROSS PARTS OF THE AREA SUNDAY. HEAT INDICES COULD RANGE FROM LOWER/MID 90S TO 100-105 FAR SOUTHWEST. DEWPOINTS THEN BACK INTO THE 70S EVERYWHERE MONDAY WITH HEAT INDICES CLOSER TO 100-105 MOST AREAS WITH STILL THE POTENTIAL TO REACH HEAT ADVISORY CRITERIA ACROSS THE FAR SOUTHERN CWA MONDAY AFTERNOON. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * RAIN WITH THE CHANCE FOR A WIDELY SCATTERED LIGHTNING STRIKE THROUGH 21Z...THEN A SMALL CHANCE FOR ISOLATED SHRA/TSRA THROUGH THIS EVE. * EAST-NORTHEAST WINDS EASING IN SPEED THROUGH LATE AFTERNOON BUT REMAINING EASTERLY IN DIRECTION. * POTENTIAL FOR IFR CIGS AND/OR VISIBILITY TONIGHT INTO SUNDAY MORNING. * LAKE BREEZE TURNING WINDS EASTERLY AROUND OR POSSIBLY ABOVE 10 KT SUNDAY. //DISCUSSION...UPDATED 20Z... LINE OF STORMS HAS MOVED EAST-SOUTHEAST OF ORD AND MDW WITH STRATIFORM RAIN TO CONTINUE THROUGH 21Z. CLOUD-TO-GROUND LIGHTNING DENSITY IN THIS HAS BEEN VERY SPARSE SO HAVE OPTED NOT TO MENTION TSRA BEYOND 20Z. EASTERLY WINDS HAVE OCCASIONALLY GUSTED ON THE BACKSIDE OF THE STORMS AND SHOULD SEE A SLOW EASE IN SPEED. THE RAINFALL ALONG WITH DIMINISHING WIND SPEED GOING TO THIS EVE...LIKELY WILL LEAD TO BETTER POTENTIAL FOR FOG AND/OR STRATUS. PREV DISCUSSION...UPDATED 18Z... AREA OF SHOWERS AND STORMS CONTINUES TO MOVE EASTWARD WITH A SLOW WANING TREND...ESPECIALLY IN PART OF THE SEGMENT JUST UPSTREAM OF ORD AND MDW. WHILE THAT IS THE CASE...INCREASED CONVERGENCE BETWEEN THE OUTFLOW AND THE LAKE BREEZE IN UNCAPPED AIR WILL LIKELY SPARK MORE STORMS. THIS ALSO COULD EXTEND THE TSRA TIMING. SO FEEL COMFORTABLE WITH THE TSRA STILL INDICATED IN THE CHICAGOLAND TAFS. STRATIFORM RAIN BEHIND THIS WILL LIKELY BE ACCOMPANIED WITH MVFR CONDITIONS. SCATTERED SHOWERS AND STORMS ARE POSSIBLE BEHIND THIS DURING THE LATTER HALF OF THE AFTERNOON INTO THE EVENING IN THE CONTINUED MOISTURE RICH AIR MASS. THE WIND DIRECTION WILL LIKELY TURN SOUTHWEST AS THE STORMS PASS...AS ALL OBSERVATIONS SITES HAVE INDICATED THAT UPSTREAM AND RADAR SHOW WELL-DEFINED OUTFLOW. THE SPEED OF THE OUTFLOW HAS SLOWED SOME...SO THE DEGREE OF GUSTS AT CHICAGOLAND TAF SITES IS EXPECTED TO BE LESS THAN 30 KT. THE WIND DIRECTION BEHIND THE INITIAL PUSH OF STORMS MAY BECOME VARIABLE...BUT IS ANTICIPATED TO TURN EAST OR SOUTHEAST BASED ON THE SYNOPTIC FLOW AND CLIMATOLOGY FOR POST-THUNDERSTORM WINDS AT ORD. THE MOISTURE IN THE LOW-LEVELS AIDED BY RAIN EARLY THIS AFTERNOON WILL SET THE STAGE ONCE AGAIN FOR FOG AND LOW CIGS TONIGHT...HOWEVER THE COVERAGE OF THIS IS DIFFICULT TO DETERMINE AT THIS TIME. A LAKE BREEZE LOOKS LIKELY ON SUNDAY AFTERNOON INTO NORTHEAST ILLINOIS THAT WILL PROBABLY REACH BOTH ORD AND MDW. //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH IN RAIN END TIME. LOW IN WHETHER ANYMORE SHRA/TSRA WILL OCCUR THROUGH THIS EVE. * MEDIUM IN WIND DIRECTION AND SPEED THROUGH EARLY THIS EVE. * MEDIUM IN SOME FORM OF IFR RESTRICTION LATE TONIGHT INTO EARLY SUNDAY MORNING. LOW ON WHETHER FOG AND/OR CIG. //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MTF && .MARINE... 153 PM CDT RELATIVELY LIGHT WINDS ARE IN PLACE THIS AFTERNOON AS A WEAK PRESSURE GRADIENT IS IN PLACE ACROSS THE REGION. WINDS WILL BEGIN TO FRESHEN UP SLIGHTLY TONIGHT AND VEER TO THE SOUTHEAST AS BROAD AREA OF LOW PRESSURE OVER THE PLAINS BEGINS TO CONSOLIDATE AND DEEPEN AS IT LIFTS TOWARDS THE CANADIAN PRAIRIES. THIS LOW WILL DRAG A WEAK COLD FRONT SOUTH ACROSS LAKE MICHIGAN LATE TUESDAY INTO WEDNESDAY WITH WINDS TURNING TO THE NORTH BEHIND THROUGH THE REMAINDER OF THE WEEK. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...DENSE FOG ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
154 PM CDT SAT AUG 23 2014 .MESOSCALE DISCUSSION... 115 PM CDT LINE OF STORMS IS MOVING EAST INTO THE CHICAGOLAND AREA EARLY THIS AFTERNOON. WHILE THIS HAS SHOWN A GRADUAL WEAKENING TREND WITH LESS LIGHTNING...DESTABILIZATION ACROSS NORTHWEST IN...EASTERN IL...AND INTO THE SOUTH CHICAGO METRO THE PAST FEW HOURS SHOULD AID IN THE ACTIVITY TO AT LEAST PERSIST WITH HEAVY RAINFALL RATES. IN ADDITION...CONVERGENCE FROM THE SYSTEM OUTFLOW AND THE LAKE BREEZE HAS ALREADY FIRED A FEW ADDITIONAL CELLS AND THAT WILL LIKELY CONTINUE TO OCCUR IN SUBURBAN AREAS THROUGH 2-3 PM. THE AREA OF STORMS ALSO SHOULD FURTHER SLOW AS IT RUNS INTO THE MARINE LAYER. THIS MAY CAUSE HEAVY RAINFALL RATES TO PERSIST OVER THE SAME URBAN AREAS FOR A WHILE...INCLUDING THOSE THAT WERE HIT HARD LATE THURSDAY NIGHT. WILL BE MONITORING CLOSELY. SEVERE THREAT APPEARS MINIMAL...WITH MAINLY THE FAR SOUTHEAST CWA BEING THE ONE AREA THAT COULD SEE AN ISOLATED FLARE UP TO THAT LEVEL. NOW THAT AREAS HAVE BEEN RAIN COOLED...WILL ADJUST TEMPERATURES CONSIDERABLY DOWNWARD THE REST OF THE AFTERNOON. MTF && .DISCUSSION... 959 AM CDT THE FORECAST HAS BEEN UPDATED TO REFLECT GREATER CLOUD COVER AREAWIDE AND HIGHER POPS ACROSS MAINLY NORTH CENTRAL ILLINOIS DURING THE EARLY-MID AFTERNOON. A BROAD MESOSCALE CONVECTIVE SYSTEM WITH A LINE OF STORMS ON ITS FRONT EDGE IS CURRENTLY ADVANCING EAST OVER THE MISSISSIPPI RIVER AND FAR WESTERN ILLINOIS. THIS CONTINUES TO HOLD TOGETHER WELL WITH ONLY SUBTLE CLOUD TOP WARMING AND NO FADE IN LIGHTNING ACTIVITY OVER THE PAST COUPLE HOURS. THIS COMPLEX HAS BEEN ONGOING FOR OVER NINE HOURS SO NOT SURPRISED TO SEE THAT THE RADAR LOOP INDICATES THE LIKELY PRESENCE OF A CONVECTIVELY-INDUCED VORTICITY MAXIMUM /MCV/ IN FAR EASTERN IA. THIS WITH A COLD POOL IS HELPING TO USHER PUSH THE STORMS MORE EASTWARD THAN THE NORTHEAST MOVEMENT OF THE PARENT SHORTWAVE WOULD INDICATE. DESPITE WHAT SHOULD BE A GRADUAL FACE INTO THE EARLY AFTERNOON WITH THE UPPER SUPPORT MOVING NORTHEAST AND A DECAYING LOW-LEVEL JET PER PROFILERS...2.2 INCH PWAT AIR /99TH PERCENTILE/ AHEAD OF THE MCV WILL LIKELY SUPPORT SHOWERS AND SOME STORMS INTO NORTH CENTRAL ILLINOIS BETWEEN NOON AND 3 PM. STILL SEEING SOME EMBEDDED HOURLY PRECIP REPORTS OF A HALF TO ONE INCH WITH THIS...AND SOME OF THIS EFFICIENCY COULD CERTAINLY OCCUR ALONG AND WEST OF I-39 DURING THE EARLY AFTERNOON. UNDER THE INFLUENCE OF WEAK UPPER LEVEL FLOW...THE MCV IS FORECAST BY THE RAP AND NAM TO CONTINUE TO SLOW AS IT MOVES INTO NORTH CENTRAL IL. DESTABILIZATION AHEAD OF IT MAY SUPPORT ISOLATED OR SCATTERED SHOWERS/STORMS LATER THIS AFTERNOON FURTHER EAST TOWARD CHICAGO AND THE I-57 CORRIDOR INTO NORTHWEST INDIANA...BUT CONFIDENCE ON THIS IS LOW AS ANVIL SHIELD WILL INHIBIT THE RATE OF WARMTH...WITH MOST GUIDANCE INDICATING THE PRESENCE OF A CAP AND LOW-LEVEL FLOW OFF THE LAKE IN FAR NORTHEAST IL. MINOR TWEAKS MADE TO HOURLY TEMPERATURES AND DEW POINTS. MTF //PREV DISCUSSION... 327 AM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES/TIMING THROUGH THE PERIOD ALONG WITH HIGH TEMPERATURES/HEAT INDICES THROUGH MONDAY. AREAS OF FOG CONTINUE TO DEVELOP WITH VISIBILITIES DROPPING UNDER 1SM IN A FEW LOCATIONS. NOT EXPECTING WIDESPREAD DENSE FOG THIS MORNING BUT WILL NEED TO MONITOR OBS OVER THE NEXT FEW HOURS. THE FOG WILL LIFT THIS MORNING BUT WITH LITTLE CHANGE TO THE AIRMASS FOG WILL BE POSSIBLE AGAIN TONIGHT INTO SUNDAY MORNING. A FEW SHOWERS DEVELOPED ACROSS NORTHERN LAKE COUNTY IN NORTHEAST IL LATE FRIDAY EVENING AND PERSISTED FOR A FEW HOURS BEFORE DISSIPATING. OTHERWISE...CONVECTION HAS BEEN FOCUSED FURTHER WEST EARLY THIS MORNING IN THE VICINITY OF THE LOW LEVEL JET. SOME OF THIS ACTIVITY OVER EASTERN IA MAY ARRIVE ACROSS THE WESTERN CWA LATER THIS MORNING...LIKELY IN A DECAYING FORM. BUT OTHER THAN AN ISOLATED SHOWER...EXPECT THE NEXT SEVERAL HOURS TO BE MAINLY DRY. CONFIDENCE REGARDING THUNDERSTORM CHANCES THIS AFTERNOON INTO THIS EVENING IS LOW THOUGH THERE IS SOME CONSENSUS FOR DEVELOPMENT BY EARLY AFTERNOON ACROSS WESTERN/NORTHWEST IL FROM REMNANTS OF CONVECTION OVER EASTERN NEBRASKA/WESTERN IA. HOW FAR IT CONTINUES EAST OR NORTHEAST BEFORE WEAKENING IS ANOTHER UNCERTAINTY. MADE NO SIGNIFICANT CHANGES FOR TODAY MAINTAINING 30-40 POPS. TRENDS WILL NEED TO BE MONITORED THRU THE MORNING. DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES APPROACHING 2 INCHES WILL LEAD TO VERY HEAVY RAIN WITH ANY THUNDERSTORMS THAT DO DEVELOP AND POSSIBLY FLASH FLOODING...ESPECIALLY IF THE RAIN FALLS OVER HARDER HIT AREAS FROM FRIDAY MORNING. THE UPPER RIDGE THEN BUILDS ACROSS THE AREA TONIGHT AND SUNDAY AND PRECIP CHANCES LOOK BELOW MENTIONABLE FROM LATE TONIGHT THROUGH MONDAY MORNING. CAN/T COMPLETELY RULE OUT SOME ISOLATED ACTIVITY... IN PARTICULAR ON A LAKE BREEZE SUNDAY AFTERNOON. A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY WITH SOME DIFFERENCES AS TO HOW FAR SOUTH THIS BOUNDARY WILL SETTLE MONDAY AFTERNOON INTO MONDAY NIGHT. THIS WOULD LIKELY BE THE NEXT CHANCE OF THUNDERSTORMS WITH THE GEM/ECMWF BOTH PUSHING THE FRONT THROUGH MUCH OF THE CWA BY TUESDAY MORNING. THIS BOUNDARY THEN MEANDERS NEAR THE IL/WI BORDER INTO THURSDAY WITH THE POSSIBILITY OF A PROLONGED UNSETTLED PATTERN ACROSS THE AREA. CLOUD COVER/CONVECTION TODAY WILL LIKELY KEEP TEMPS IN THE 80S... THOUGH WITH THE URBAN AREAS STARTING FROM LOWER/MID 70S...ANY LONGER PERIOD OF SUNSHINE TODAY COULD ALLOW A FEW PLACES TO TAG 90. TEMPS WILL WARM A FEW DEGREES SUNDAY BUT SOUTHEASTERLY WINDS WILL KEEP THE LAKESHORE COOLER. MONDAY LOOKS TO BE THE BEST CHANCE FOR TEMPS INTO THE LOWER 90S CWA WIDE BUT WILL BE DEPENDENT ON CLOUD COVER AND TIMING/ARRIVAL OF ANY PRECIP. DEWPOINTS MAY LOWER A FEW DEGREES...BACK INTO THE MID/UPPER 60S ACROSS PARTS OF THE AREA SUNDAY. HEAT INDICES COULD RANGE FROM LOWER/MID 90S TO 100-105 FAR SOUTHWEST. DEWPOINTS THEN BACK INTO THE 70S EVERYWHERE MONDAY WITH HEAT INDICES CLOSER TO 100-105 MOST AREAS WITH STILL THE POTENTIAL TO REACH HEAT ADVISORY CRITERIA ACROSS THE FAR SOUTHERN CWA MONDAY AFTERNOON. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * RAIN WITH A PERIOD OF THUNDER AND POSSIBLE IFR VISIBILITY BETWEEN 19Z-21Z...WITH THE POTENTIAL FOR LINGERING SCATTERED SHRA/TSRA INTO THE EVE. * EAST-NORTHEAST WINDS SHIFTING SOUTHWEST WITH SHOWERS AND STORMS THEN LIKELY BECOMING SOUTHEAST OR EAST AFTERWARD /NEAR 20Z/ AND POTENTIALLY BEING AROUND 10 KT. * POTENTIAL FOR IFR CIGS AND/OR VISIBILITY TONIGHT INTO SUNDAY MORNING. * LAKE BREEZE TURNING WINDS EASTERLY AROUND OR POSSIBLY ABOVE 10 KT SUNDAY. //DISCUSSION...UPDATED 18Z... AREA OF SHOWERS AND STORMS CONTINUES TO MOVE EASTWARD WITH A SLOW WANING TREND...ESPECIALLY IN PART OF THE SEGMENT JUST UPSTREAM OF ORD AND MDW. WHILE THAT IS THE CASE...INCREASED CONVERGENCE BETWEEN THE OUTFLOW AND THE LAKE BREEZE IN UNCAPPED AIR WILL LIKELY SPARK MORE STORMS. THIS ALSO COULD EXTEND THE TSRA TIMING. SO FEEL COMFORTABLE WITH THE TSRA STILL INDICATED IN THE CHICAGOLAND TAFS. STRATIFORM RAIN BEHIND THIS WILL LIKELY BE ACCOMPANIED WITH MVFR CONDITIONS. SCATTERED SHOWERS AND STORMS ARE POSSIBLE BEHIND THIS DURING THE LATTER HALF OF THE AFTERNOON INTO THE EVENING IN THE CONTINUED MOISTURE RICH AIR MASS. THE WIND DIRECTION WILL LIKELY TURN SOUTHWEST AS THE STORMS PASS...AS ALL OBSERVATIONS SITES HAVE INDICATED THAT UPSTREAM AND RADAR SHOW WELL-DEFINED OUTFLOW. THE SPEED OF THE OUTFLOW HAS SLOWED SOME...SO THE DEGREE OF GUSTS AT CHICAGOLAND TAF SITES IS EXPECTED TO BE LESS THAN 30 KT. THE WIND DIRECTION BEHIND THE INITIAL PUSH OF STORMS MAY BECOME VARIABLE...BUT IS ANTICIPATED TO TURN EAST OR SOUTHEAST BASED ON THE SYNOPTIC FLOW AND CLIMATOLOGY FOR POST-THUNDERSTORM WINDS AT ORD. THE MOISTURE IN THE LOW-LEVELS AIDED BY RAIN EARLY THIS AFTERNOON WILL SET THE STAGE ONCE AGAIN FOR FOG AND LOW CIGS TONIGHT...HOWEVER THE COVERAGE OF THIS IS DIFFICULT TO DETERMINE AT THIS TIME. A LAKE BREEZE LOOKS LIKELY ON SUNDAY AFTERNOON INTO NORTHEAST ILLINOIS THAT WILL PROBABLY REACH BOTH ORD AND MDW. //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH IN THUNDER OCCURRING. MEDIUM IN DURATION. LOW IN SHRA/TSRA CHANCES THIS EVE. * LOW IN WIND DIRECTION BETWEEN 19Z AND 21Z...MEDIUM IN WIND CONDITIONS OTHERWISE...INCLUDING LAKE BREEZE TIMING ON SUNDAY. * MEDIUM IN SOME FORM OF IFR RESTRICTION LATE TONIGHT INTO EARLY SUNDAY MORNING. LOW ON WHETHER FOG AND/OR CIG. //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MTF && .MARINE... 153 PM CDT RELATIVELY LIGHT WINDS ARE IN PLACE THIS AFTERNOON AS A WEAK PRESSURE GRADIENT IS IN PLACE ACROSS THE REGION. WINDS WILL BEGIN TO FRESHEN UP SLIGHTLY TONIGHT AND VEER TO THE SOUTHEAST AS BROAD AREA OF LOW PRESSURE OVER THE PLAINS BEGINS TO CONSOLIDATE AND DEEPEN AS IT LIFTS TOWARDS THE CANADIAN PRAIRIES. THIS LOW WILL DRAG A WEAK COLD FRONT SOUTH ACROSS LAKE MICHIGAN LATE TUESDAY INTO WEDNESDAY WITH WINDS TURNING TO THE NORTH BEHIND THROUGH THE REMAINDER OF THE WEEK. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...DENSE FOG ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
117 PM CDT SAT AUG 23 2014 .MESOSCALE DISCUSSION... 115 PM CDT LINE OF STORMS IS MOVING EAST INTO THE CHICAGOLAND AREA EARLY THIS AFTERNOON. WHILE THIS HAS SHOWN A GRADUAL WEAKENING TREND WITH LESS LIGHTNING...DESTABILIZATION ACROSS NORTHWEST IN...EASTERN IL...AND INTO THE SOUTH CHICAGO METRO THE PAST FEW HOURS SHOULD AID IN THE ACTIVITY TO AT LEAST PERSIST WITH HEAVY RAINFALL RATES. IN ADDITION...CONVERGENCE FROM THE SYSTEM OUTFLOW AND THE LAKE BREEZE HAS ALREADY FIRED A FEW ADDITIONAL CELLS AND THAT WILL LIKELY CONTINUE TO OCCUR IN SUBURBAN AREAS THROUGH 2-3 PM. THE AREA OF STORMS ALSO SHOULD FURTHER SLOW AS IT RUNS INTO THE MARINE LAYER. THIS MAY CAUSE HEAVY RAINFALL RATES TO PERSIST OVER THE SAME URBAN AREAS FOR A WHILE...INCLUDING THOSE THAT WERE HIT HARD LATE THURSDAY NIGHT. WILL BE MONITORING CLOSELY. SEVERE THREAT APPEARS MINIMAL...WITH MAINLY THE FAR SOUTHEAST CWA BEING THE ONE AREA THAT COULD SEE AN ISOLATED FLARE UP TO THAT LEVEL. NOW THAT AREAS HAVE BEEN RAIN COOLED...WILL ADJUST TEMPERATURES CONSIDERABLY DOWNWARD THE REST OF THE AFTERNOON. MTF && .DISCUSSION... 959 AM CDT THE FORECAST HAS BEEN UPDATED TO REFLECT GREATER CLOUD COVER AREAWIDE AND HIGHER POPS ACROSS MAINLY NORTH CENTRAL ILLINOIS DURING THE EARLY-MID AFTERNOON. A BROAD MESOSCALE CONVECTIVE SYSTEM WITH A LINE OF STORMS ON ITS FRONT EDGE IS CURRENTLY ADVANCING EAST OVER THE MISSISSIPPI RIVER AND FAR WESTERN ILLINOIS. THIS CONTINUES TO HOLD TOGETHER WELL WITH ONLY SUBTLE CLOUD TOP WARMING AND NO FADE IN LIGHTNING ACTIVITY OVER THE PAST COUPLE HOURS. THIS COMPLEX HAS BEEN ONGOING FOR OVER NINE HOURS SO NOT SURPRISED TO SEE THAT THE RADAR LOOP INDICATES THE LIKELY PRESENCE OF A CONVECTIVELY-INDUCED VORTICITY MAXIMUM /MCV/ IN FAR EASTERN IA. THIS WITH A COLD POOL IS HELPING TO USHER PUSH THE STORMS MORE EASTWARD THAN THE NORTHEAST MOVEMENT OF THE PARENT SHORTWAVE WOULD INDICATE. DESPITE WHAT SHOULD BE A GRADUAL FACE INTO THE EARLY AFTERNOON WITH THE UPPER SUPPORT MOVING NORTHEAST AND A DECAYING LOW-LEVEL JET PER PROFILERS...2.2 INCH PWAT AIR /99TH PERCENTILE/ AHEAD OF THE MCV WILL LIKELY SUPPORT SHOWERS AND SOME STORMS INTO NORTH CENTRAL ILLINOIS BETWEEN NOON AND 3 PM. STILL SEEING SOME EMBEDDED HOURLY PRECIP REPORTS OF A HALF TO ONE INCH WITH THIS...AND SOME OF THIS EFFICIENCY COULD CERTAINLY OCCUR ALONG AND WEST OF I-39 DURING THE EARLY AFTERNOON. UNDER THE INFLUENCE OF WEAK UPPER LEVEL FLOW...THE MCV IS FORECAST BY THE RAP AND NAM TO CONTINUE TO SLOW AS IT MOVES INTO NORTH CENTRAL IL. DESTABILIZATION AHEAD OF IT MAY SUPPORT ISOLATED OR SCATTERED SHOWERS/STORMS LATER THIS AFTERNOON FURTHER EAST TOWARD CHICAGO AND THE I-57 CORRIDOR INTO NORTHWEST INDIANA...BUT CONFIDENCE ON THIS IS LOW AS ANVIL SHIELD WILL INHIBIT THE RATE OF WARMTH...WITH MOST GUIDANCE INDICATING THE PRESENCE OF A CAP AND LOW-LEVEL FLOW OFF THE LAKE IN FAR NORTHEAST IL. MINOR TWEAKS MADE TO HOURLY TEMPERATURES AND DEW POINTS. MTF //PREV DISCUSSION... 327 AM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES/TIMING THROUGH THE PERIOD ALONG WITH HIGH TEMPERATURES/HEAT INDICES THROUGH MONDAY. AREAS OF FOG CONTINUE TO DEVELOP WITH VISIBILITIES DROPPING UNDER 1SM IN A FEW LOCATIONS. NOT EXPECTING WIDESPREAD DENSE FOG THIS MORNING BUT WILL NEED TO MONITOR OBS OVER THE NEXT FEW HOURS. THE FOG WILL LIFT THIS MORNING BUT WITH LITTLE CHANGE TO THE AIRMASS FOG WILL BE POSSIBLE AGAIN TONIGHT INTO SUNDAY MORNING. A FEW SHOWERS DEVELOPED ACROSS NORTHERN LAKE COUNTY IN NORTHEAST IL LATE FRIDAY EVENING AND PERSISTED FOR A FEW HOURS BEFORE DISSIPATING. OTHERWISE...CONVECTION HAS BEEN FOCUSED FURTHER WEST EARLY THIS MORNING IN THE VICINITY OF THE LOW LEVEL JET. SOME OF THIS ACTIVITY OVER EASTERN IA MAY ARRIVE ACROSS THE WESTERN CWA LATER THIS MORNING...LIKELY IN A DECAYING FORM. BUT OTHER THAN AN ISOLATED SHOWER...EXPECT THE NEXT SEVERAL HOURS TO BE MAINLY DRY. CONFIDENCE REGARDING THUNDERSTORM CHANCES THIS AFTERNOON INTO THIS EVENING IS LOW THOUGH THERE IS SOME CONSENSUS FOR DEVELOPMENT BY EARLY AFTERNOON ACROSS WESTERN/NORTHWEST IL FROM REMNANTS OF CONVECTION OVER EASTERN NEBRASKA/WESTERN IA. HOW FAR IT CONTINUES EAST OR NORTHEAST BEFORE WEAKENING IS ANOTHER UNCERTAINTY. MADE NO SIGNIFICANT CHANGES FOR TODAY MAINTAINING 30-40 POPS. TRENDS WILL NEED TO BE MONITORED THRU THE MORNING. DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES APPROACHING 2 INCHES WILL LEAD TO VERY HEAVY RAIN WITH ANY THUNDERSTORMS THAT DO DEVELOP AND POSSIBLY FLASH FLOODING...ESPECIALLY IF THE RAIN FALLS OVER HARDER HIT AREAS FROM FRIDAY MORNING. THE UPPER RIDGE THEN BUILDS ACROSS THE AREA TONIGHT AND SUNDAY AND PRECIP CHANCES LOOK BELOW MENTIONABLE FROM LATE TONIGHT THROUGH MONDAY MORNING. CAN/T COMPLETELY RULE OUT SOME ISOLATED ACTIVITY... IN PARTICULAR ON A LAKE BREEZE SUNDAY AFTERNOON. A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY WITH SOME DIFFERENCES AS TO HOW FAR SOUTH THIS BOUNDARY WILL SETTLE MONDAY AFTERNOON INTO MONDAY NIGHT. THIS WOULD LIKELY BE THE NEXT CHANCE OF THUNDERSTORMS WITH THE GEM/ECMWF BOTH PUSHING THE FRONT THROUGH MUCH OF THE CWA BY TUESDAY MORNING. THIS BOUNDARY THEN MEANDERS NEAR THE IL/WI BORDER INTO THURSDAY WITH THE POSSIBILITY OF A PROLONGED UNSETTLED PATTERN ACROSS THE AREA. CLOUD COVER/CONVECTION TODAY WILL LIKELY KEEP TEMPS IN THE 80S... THOUGH WITH THE URBAN AREAS STARTING FROM LOWER/MID 70S...ANY LONGER PERIOD OF SUNSHINE TODAY COULD ALLOW A FEW PLACES TO TAG 90. TEMPS WILL WARM A FEW DEGREES SUNDAY BUT SOUTHEASTERLY WINDS WILL KEEP THE LAKESHORE COOLER. MONDAY LOOKS TO BE THE BEST CHANCE FOR TEMPS INTO THE LOWER 90S CWA WIDE BUT WILL BE DEPENDENT ON CLOUD COVER AND TIMING/ARRIVAL OF ANY PRECIP. DEWPOINTS MAY LOWER A FEW DEGREES...BACK INTO THE MID/UPPER 60S ACROSS PARTS OF THE AREA SUNDAY. HEAT INDICES COULD RANGE FROM LOWER/MID 90S TO 100-105 FAR SOUTHWEST. DEWPOINTS THEN BACK INTO THE 70S EVERYWHERE MONDAY WITH HEAT INDICES CLOSER TO 100-105 MOST AREAS WITH STILL THE POTENTIAL TO REACH HEAT ADVISORY CRITERIA ACROSS THE FAR SOUTHERN CWA MONDAY AFTERNOON. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * RAIN WITH A PERIOD OF THUNDER AND POSSIBLE IFR VISIBILITY BETWEEN 19Z-21Z...WITH THE POTENTIAL FOR LINGERING SCATTERED SHRA/TSRA INTO THE EVE. * EAST-NORTHEAST WINDS SHIFTING SOUTHWEST WITH SHOWERS AND STORMS THEN LIKELY BECOMING SOUTHEAST OR EAST AFTERWARD /NEAR 20Z/ AND POTENTIALLY BEING AROUND 10 KT. * POTENTIAL FOR IFR CIGS AND/OR VISIBILITY TONIGHT INTO SUNDAY MORNING. * LAKE BREEZE TURNING WINDS EASTERLY AROUND OR POSSIBLY ABOVE 10 KT SUNDAY. //DISCUSSION...UPDATED 18Z... AREA OF SHOWERS AND STORMS CONTINUES TO MOVE EASTWARD WITH A SLOW WANING TREND...ESPECIALLY IN PART OF THE SEGMENT JUST UPSTREAM OF ORD AND MDW. WHILE THAT IS THE CASE...INCREASED CONVERGENCE BETWEEN THE OUTFLOW AND THE LAKE BREEZE IN UNCAPPED AIR WILL LIKELY SPARK MORE STORMS. THIS ALSO COULD EXTEND THE TSRA TIMING. SO FEEL COMFORTABLE WITH THE TSRA STILL INDICATED IN THE CHICAGOLAND TAFS. STRATIFORM RAIN BEHIND THIS WILL LIKELY BE ACCOMPANIED WITH MVFR CONDITIONS. SCATTERED SHOWERS AND STORMS ARE POSSIBLE BEHIND THIS DURING THE LATTER HALF OF THE AFTERNOON INTO THE EVENING IN THE CONTINUED MOISTURE RICH AIR MASS. THE WIND DIRECTION WILL LIKELY TURN SOUTHWEST AS THE STORMS PASS...AS ALL OBSERVATIONS SITES HAVE INDICATED THAT UPSTREAM AND RADAR SHOW WELL-DEFINED OUTFLOW. THE SPEED OF THE OUTFLOW HAS SLOWED SOME...SO THE DEGREE OF GUSTS AT CHICAGOLAND TAF SITES IS EXPECTED TO BE LESS THAN 30 KT. THE WIND DIRECTION BEHIND THE INITIAL PUSH OF STORMS MAY BECOME VARIABLE...BUT IS ANTICIPATED TO TURN EAST OR SOUTHEAST BASED ON THE SYNOPTIC FLOW AND CLIMATOLOGY FOR POST-THUNDERSTORM WINDS AT ORD. THE MOISTURE IN THE LOW-LEVELS AIDED BY RAIN EARLY THIS AFTERNOON WILL SET THE STAGE ONCE AGAIN FOR FOG AND LOW CIGS TONIGHT...HOWEVER THE COVERAGE OF THIS IS DIFFICULT TO DETERMINE AT THIS TIME. A LAKE BREEZE LOOKS LIKELY ON SUNDAY AFTERNOON INTO NORTHEAST ILLINOIS THAT WILL PROBABLY REACH BOTH ORD AND MDW. //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH IN THUNDER OCCURRING. MEDIUM IN DURATION. LOW IN SHRA/TSRA CHANCES THIS EVE. * LOW IN WIND DIRECTION BETWEEN 19Z AND 21Z...MEDIUM IN WIND CONDITIONS OTHERWISE...INCLUDING LAKE BREEZE TIMING ON SUNDAY. * MEDIUM IN SOME FORM OF IFR RESTRICTION LATE TONIGHT INTO EARLY SUNDAY MORNING. LOW ON WHETHER FOG AND/OR CIG. //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MTF && .MARINE... 340 AM CDT BROAD LOW PRESSURE REMAINS ACROSS THE MID MISSISSIPPI RIVER VALLEY THIS MORNING WHILE STRONGER LOW PRESSURE ORGANIZES OVER THE CENTRAL HIGH PLAINS. AN UPPER LOW SPINNING OVER THE NORTHWEST U.S. WILL HELP KICK THE HIGH PLAINS LOW NORTHWARD INTO SUNDAY WHILE HIGH PRESSURE MOVES FROM QUEBEC TO NEW ENGLAND AND THE MID-ATLANTIC STATES. EAST TO NORTHEAST WINDS WILL CONTINUE ACROSS LAKE MICHIGAN TODAY BUT WILL SHIFT TO THE SOUTHEAST INTO SUNDAY...WITH SPEEDS INCREASING MODESTLY. THE MAIN TRACK OF LOW PRESSURE WILL REMAIN OFF TO THE NORTHWEST OF THE LAKE INTO THE MIDDLE OF NEXT WEEK WHICH WILL KEEP A SOUTHERLY WIND GOING...THOUGH SOUTHERN AREAS MAY SEE WINDS SHIFT ONSHORE EACH AFTERNOON WHERE THE PRESSURE GRADIENT IS WEAKER. A FRONTAL BOUNDARY IS EXPECTED TO DROP OVER NORTHERN PARTS OF THE LAKE TOWARD MIDWEEK WHICH WOULD LEAD TO EAST OR NORTHEAST WINDS ACROSS THE NORTH WITH SOUTHERLY WINDS CONTINUING SOUTH. MEDIUM RANGE GUIDANCE CONFLICTS WITH HOW QUICKLY THIS FRONT MOVES ACROSS THE LAKE AND THE STRENGTH OF COLD AIR BEHIND IT DURING THE MIDDLE OF NEXT WEEK LEADING TO LOW FORECAST CONFIDENCE BY THAT TIME. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...DENSE FOG ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
109 PM CDT SAT AUG 23 2014 .DISCUSSION... 959 AM CDT THE FORECAST HAS BEEN UPDATED TO REFLECT GREATER CLOUD COVER AREAWIDE AND HIGHER POPS ACROSS MAINLY NORTH CENTRAL ILLINOIS DURING THE EARLY-MID AFTERNOON. A BROAD MESOSCALE CONVECTIVE SYSTEM WITH A LINE OF STORMS ON ITS FRONT EDGE IS CURRENTLY ADVANCING EAST OVER THE MISSISSIPPI RIVER AND FAR WESTERN ILLINOIS. THIS CONTINUES TO HOLD TOGETHER WELL WITH ONLY SUBTLE CLOUD TOP WARMING AND NO FADE IN LIGHTNING ACTIVITY OVER THE PAST COUPLE HOURS. THIS COMPLEX HAS BEEN ONGOING FOR OVER NINE HOURS SO NOT SURPRISED TO SEE THAT THE RADAR LOOP INDICATES THE LIKELY PRESENCE OF A CONVECTIVELY-INDUCED VORTICITY MAXIMUM /MCV/ IN FAR EASTERN IA. THIS WITH A COLD POOL IS HELPING TO USHER PUSH THE STORMS MORE EASTWARD THAN THE NORTHEAST MOVEMENT OF THE PARENT SHORTWAVE WOULD INDICATE. DESPITE WHAT SHOULD BE A GRADUAL FACE INTO THE EARLY AFTERNOON WITH THE UPPER SUPPORT MOVING NORTHEAST AND A DECAYING LOW-LEVEL JET PER PROFILERS...2.2 INCH PWAT AIR /99TH PERCENTILE/ AHEAD OF THE MCV WILL LIKELY SUPPORT SHOWERS AND SOME STORMS INTO NORTH CENTRAL ILLINOIS BETWEEN NOON AND 3 PM. STILL SEEING SOME EMBEDDED HOURLY PRECIP REPORTS OF A HALF TO ONE INCH WITH THIS...AND SOME OF THIS EFFICIENCY COULD CERTAINLY OCCUR ALONG AND WEST OF I-39 DURING THE EARLY AFTERNOON. UNDER THE INFLUENCE OF WEAK UPPER LEVEL FLOW...THE MCV IS FORECAST BY THE RAP AND NAM TO CONTINUE TO SLOW AS IT MOVES INTO NORTH CENTRAL IL. DESTABILIZATION AHEAD OF IT MAY SUPPORT ISOLATED OR SCATTERED SHOWERS/STORMS LATER THIS AFTERNOON FURTHER EAST TOWARD CHICAGO AND THE I-57 CORRIDOR INTO NORTHWEST INDIANA...BUT CONFIDENCE ON THIS IS LOW AS ANVIL SHIELD WILL INHIBIT THE RATE OF WARMTH...WITH MOST GUIDANCE INDICATING THE PRESENCE OF A CAP AND LOW-LEVEL FLOW OFF THE LAKE IN FAR NORTHEAST IL. MINOR TWEAKS MADE TO HOURLY TEMPERATURES AND DEW POINTS. MTF //PREV DISCUSSION... 327 AM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES/TIMING THROUGH THE PERIOD ALONG WITH HIGH TEMPERATURES/HEAT INDICES THROUGH MONDAY. AREAS OF FOG CONTINUE TO DEVELOP WITH VISIBILITIES DROPPING UNDER 1SM IN A FEW LOCATIONS. NOT EXPECTING WIDESPREAD DENSE FOG THIS MORNING BUT WILL NEED TO MONITOR OBS OVER THE NEXT FEW HOURS. THE FOG WILL LIFT THIS MORNING BUT WITH LITTLE CHANGE TO THE AIRMASS FOG WILL BE POSSIBLE AGAIN TONIGHT INTO SUNDAY MORNING. A FEW SHOWERS DEVELOPED ACROSS NORTHERN LAKE COUNTY IN NORTHEAST IL LATE FRIDAY EVENING AND PERSISTED FOR A FEW HOURS BEFORE DISSIPATING. OTHERWISE...CONVECTION HAS BEEN FOCUSED FURTHER WEST EARLY THIS MORNING IN THE VICINITY OF THE LOW LEVEL JET. SOME OF THIS ACTIVITY OVER EASTERN IA MAY ARRIVE ACROSS THE WESTERN CWA LATER THIS MORNING...LIKELY IN A DECAYING FORM. BUT OTHER THAN AN ISOLATED SHOWER...EXPECT THE NEXT SEVERAL HOURS TO BE MAINLY DRY. CONFIDENCE REGARDING THUNDERSTORM CHANCES THIS AFTERNOON INTO THIS EVENING IS LOW THOUGH THERE IS SOME CONSENSUS FOR DEVELOPMENT BY EARLY AFTERNOON ACROSS WESTERN/NORTHWEST IL FROM REMNANTS OF CONVECTION OVER EASTERN NEBRASKA/WESTERN IA. HOW FAR IT CONTINUES EAST OR NORTHEAST BEFORE WEAKENING IS ANOTHER UNCERTAINTY. MADE NO SIGNIFICANT CHANGES FOR TODAY MAINTAINING 30-40 POPS. TRENDS WILL NEED TO BE MONITORED THRU THE MORNING. DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES APPROACHING 2 INCHES WILL LEAD TO VERY HEAVY RAIN WITH ANY THUNDERSTORMS THAT DO DEVELOP AND POSSIBLY FLASH FLOODING...ESPECIALLY IF THE RAIN FALLS OVER HARDER HIT AREAS FROM FRIDAY MORNING. THE UPPER RIDGE THEN BUILDS ACROSS THE AREA TONIGHT AND SUNDAY AND PRECIP CHANCES LOOK BELOW MENTIONABLE FROM LATE TONIGHT THROUGH MONDAY MORNING. CAN/T COMPLETELY RULE OUT SOME ISOLATED ACTIVITY... IN PARTICULAR ON A LAKE BREEZE SUNDAY AFTERNOON. A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY WITH SOME DIFFERENCES AS TO HOW FAR SOUTH THIS BOUNDARY WILL SETTLE MONDAY AFTERNOON INTO MONDAY NIGHT. THIS WOULD LIKELY BE THE NEXT CHANCE OF THUNDERSTORMS WITH THE GEM/ECMWF BOTH PUSHING THE FRONT THROUGH MUCH OF THE CWA BY TUESDAY MORNING. THIS BOUNDARY THEN MEANDERS NEAR THE IL/WI BORDER INTO THURSDAY WITH THE POSSIBILITY OF A PROLONGED UNSETTLED PATTERN ACROSS THE AREA. CLOUD COVER/CONVECTION TODAY WILL LIKELY KEEP TEMPS IN THE 80S... THOUGH WITH THE URBAN AREAS STARTING FROM LOWER/MID 70S...ANY LONGER PERIOD OF SUNSHINE TODAY COULD ALLOW A FEW PLACES TO TAG 90. TEMPS WILL WARM A FEW DEGREES SUNDAY BUT SOUTHEASTERLY WINDS WILL KEEP THE LAKESHORE COOLER. MONDAY LOOKS TO BE THE BEST CHANCE FOR TEMPS INTO THE LOWER 90S CWA WIDE BUT WILL BE DEPENDENT ON CLOUD COVER AND TIMING/ARRIVAL OF ANY PRECIP. DEWPOINTS MAY LOWER A FEW DEGREES...BACK INTO THE MID/UPPER 60S ACROSS PARTS OF THE AREA SUNDAY. HEAT INDICES COULD RANGE FROM LOWER/MID 90S TO 100-105 FAR SOUTHWEST. DEWPOINTS THEN BACK INTO THE 70S EVERYWHERE MONDAY WITH HEAT INDICES CLOSER TO 100-105 MOST AREAS WITH STILL THE POTENTIAL TO REACH HEAT ADVISORY CRITERIA ACROSS THE FAR SOUTHERN CWA MONDAY AFTERNOON. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * RAIN WITH A PERIOD OF THUNDER AND POSSIBLE IFR VISIBILITY BETWEEN 19Z-21Z...WITH THE POTENTIAL FOR LINGERING SCATTERED SHRA/TSRA INTO THE EVE. * EAST-NORTHEAST WINDS SHIFTING SOUTHWEST WITH SHOWERS AND STORMS THEN LIKELY BECOMING SOUTHEAST OR EAST AFTERWARD /NEAR 20Z/ AND POTENTIALLY BEING AROUND 10 KT. * POTENTIAL FOR IFR CIGS AND/OR VISIBILITY TONIGHT INTO SUNDAY MORNING. * LAKE BREEZE TURNING WINDS EASTERLY AROUND OR POSSIBLY ABOVE 10 KT SUNDAY. //DISCUSSION...UPDATED 18Z... AREA OF SHOWERS AND STORMS CONTINUES TO MOVE EASTWARD WITH A SLOW WANING TREND...ESPECIALLY IN PART OF THE SEGMENT JUST UPSTREAM OF ORD AND MDW. WHILE THAT IS THE CASE...INCREASED CONVERGENCE BETWEEN THE OUTFLOW AND THE LAKE BREEZE IN UNCAPPED AIR WILL LIKELY SPARK MORE STORMS. THIS ALSO COULD EXTEND THE TSRA TIMING. SO FEEL COMFORTABLE WITH THE TSRA STILL INDICATED IN THE CHICAGOLAND TAFS. STRATIFORM RAIN BEHIND THIS WILL LIKELY BE ACCOMPANIED WITH MVFR CONDITIONS. SCATTERED SHOWERS AND STORMS ARE POSSIBLE BEHIND THIS DURING THE LATTER HALF OF THE AFTERNOON INTO THE EVENING IN THE CONTINUED MOISTURE RICH AIR MASS. THE WIND DIRECTION WILL LIKELY TURN SOUTHWEST AS THE STORMS PASS...AS ALL OBSERVATIONS SITES HAVE INDICATED THAT UPSTREAM AND RADAR SHOW WELL-DEFINED OUTFLOW. THE SPEED OF THE OUTFLOW HAS SLOWED SOME...SO THE DEGREE OF GUSTS AT CHICAGOLAND TAF SITES IS EXPECTED TO BE LESS THAN 30 KT. THE WIND DIRECTION BEHIND THE INITIAL PUSH OF STORMS MAY BECOME VARIABLE...BUT IS ANTICIPATED TO TURN EAST OR SOUTHEAST BASED ON THE SYNOPTIC FLOW AND CLIMATOLOGY FOR POST-THUNDERSTORM WINDS AT ORD. THE MOISTURE IN THE LOW-LEVELS AIDED BY RAIN EARLY THIS AFTERNOON WILL SET THE STAGE ONCE AGAIN FOR FOG AND LOW CIGS TONIGHT...HOWEVER THE COVERAGE OF THIS IS DIFFICULT TO DETERMINE AT THIS TIME. A LAKE BREEZE LOOKS LIKELY ON SUNDAY AFTERNOON INTO NORTHEAST ILLINOIS THAT WILL PROBABLY REACH BOTH ORD AND MDW. //ORD AND MDW CONFIDENCE...UPDATED 18Z... * HIGH IN THUNDER OCCURRING. MEDIUM IN DURATION. LOW IN SHRA/TSRA CHANCES THIS EVE. * LOW IN WIND DIRECTION BETWEEN 19Z AND 21Z...MEDIUM IN WIND CONDITIONS OTHERWISE...INCLUDING LAKE BREEZE TIMING ON SUNDAY. * MEDIUM IN SOME FORM OF IFR RESTRICTION LATE TONIGHT INTO EARLY SUNDAY MORNING. LOW ON WHETHER FOG AND/OR CIG. //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MTF && .MARINE... 340 AM CDT BROAD LOW PRESSURE REMAINS ACROSS THE MID MISSISSIPPI RIVER VALLEY THIS MORNING WHILE STRONGER LOW PRESSURE ORGANIZES OVER THE CENTRAL HIGH PLAINS. AN UPPER LOW SPINNING OVER THE NORTHWEST U.S. WILL HELP KICK THE HIGH PLAINS LOW NORTHWARD INTO SUNDAY WHILE HIGH PRESSURE MOVES FROM QUEBEC TO NEW ENGLAND AND THE MID-ATLANTIC STATES. EAST TO NORTHEAST WINDS WILL CONTINUE ACROSS LAKE MICHIGAN TODAY BUT WILL SHIFT TO THE SOUTHEAST INTO SUNDAY...WITH SPEEDS INCREASING MODESTLY. THE MAIN TRACK OF LOW PRESSURE WILL REMAIN OFF TO THE NORTHWEST OF THE LAKE INTO THE MIDDLE OF NEXT WEEK WHICH WILL KEEP A SOUTHERLY WIND GOING...THOUGH SOUTHERN AREAS MAY SEE WINDS SHIFT ONSHORE EACH AFTERNOON WHERE THE PRESSURE GRADIENT IS WEAKER. A FRONTAL BOUNDARY IS EXPECTED TO DROP OVER NORTHERN PARTS OF THE LAKE TOWARD MIDWEEK WHICH WOULD LEAD TO EAST OR NORTHEAST WINDS ACROSS THE NORTH WITH SOUTHERLY WINDS CONTINUING SOUTH. MEDIUM RANGE GUIDANCE CONFLICTS WITH HOW QUICKLY THIS FRONT MOVES ACROSS THE LAKE AND THE STRENGTH OF COLD AIR BEHIND IT DURING THE MIDDLE OF NEXT WEEK LEADING TO LOW FORECAST CONFIDENCE BY THAT TIME. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...DENSE FOG ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1123 AM CDT SAT AUG 23 2014 .DISCUSSION... 959 AM CDT THE FORECAST HAS BEEN UPDATED TO REFLECT GREATER CLOUD COVER AREAWIDE AND HIGHER POPS ACROSS MAINLY NORTH CENTRAL ILLINOIS DURING THE EARLY-MID AFTERNOON. A BROAD MESOSCALE CONVECTIVE SYSTEM WITH A LINE OF STORMS ON ITS FRONT EDGE IS CURRENTLY ADVANCING EAST OVER THE MISSISSIPPI RIVER AND FAR WESTERN ILLINOIS. THIS CONTINUES TO HOLD TOGETHER WELL WITH ONLY SUBTLE CLOUD TOP WARMING AND NO FADE IN LIGHTNING ACTIVITY OVER THE PAST COUPLE HOURS. THIS COMPLEX HAS BEEN ONGOING FOR OVER NINE HOURS SO NOT SURPRISED TO SEE THAT THE RADAR LOOP INDICATES THE LIKELY PRESENCE OF A CONVECTIVELY-INDUCED VORTICITY MAXIMUM /MCV/ IN FAR EASTERN IA. THIS WITH A COLD POOL IS HELPING TO USHER PUSH THE STORMS MORE EASTWARD THAN THE NORTHEAST MOVEMENT OF THE PARENT SHORTWAVE WOULD INDICATE. DESPITE WHAT SHOULD BE A GRADUAL FACE INTO THE EARLY AFTERNOON WITH THE UPPER SUPPORT MOVING NORTHEAST AND A DECAYING LOW-LEVEL JET PER PROFILERS...2.2 INCH PWAT AIR /99TH PERCENTILE/ AHEAD OF THE MCV WILL LIKELY SUPPORT SHOWERS AND SOME STORMS INTO NORTH CENTRAL ILLINOIS BETWEEN NOON AND 3 PM. STILL SEEING SOME EMBEDDED HOURLY PRECIP REPORTS OF A HALF TO ONE INCH WITH THIS...AND SOME OF THIS EFFICIENCY COULD CERTAINLY OCCUR ALONG AND WEST OF I-39 DURING THE EARLY AFTERNOON. UNDER THE INFLUENCE OF WEAK UPPER LEVEL FLOW...THE MCV IS FORECAST BY THE RAP AND NAM TO CONTINUE TO SLOW AS IT MOVES INTO NORTH CENTRAL IL. DESTABILIZATION AHEAD OF IT MAY SUPPORT ISOLATED OR SCATTERED SHOWERS/STORMS LATER THIS AFTERNOON FURTHER EAST TOWARD CHICAGO AND THE I-57 CORRIDOR INTO NORTHWEST INDIANA...BUT CONFIDENCE ON THIS IS LOW AS ANVIL SHIELD WILL INHIBIT THE RATE OF WARMTH...WITH MOST GUIDANCE INDICATING THE PRESENCE OF A CAP AND LOW-LEVEL FLOW OFF THE LAKE IN FAR NORTHEAST IL. MINOR TWEAKS MADE TO HOURLY TEMPERATURES AND DEW POINTS. MTF //PREV DISCUSSION... 327 AM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES/TIMING THROUGH THE PERIOD ALONG WITH HIGH TEMPERATURES/HEAT INDICES THROUGH MONDAY. AREAS OF FOG CONTINUE TO DEVELOP WITH VISIBILITIES DROPPING UNDER 1SM IN A FEW LOCATIONS. NOT EXPECTING WIDESPREAD DENSE FOG THIS MORNING BUT WILL NEED TO MONITOR OBS OVER THE NEXT FEW HOURS. THE FOG WILL LIFT THIS MORNING BUT WITH LITTLE CHANGE TO THE AIRMASS FOG WILL BE POSSIBLE AGAIN TONIGHT INTO SUNDAY MORNING. A FEW SHOWERS DEVELOPED ACROSS NORTHERN LAKE COUNTY IN NORTHEAST IL LATE FRIDAY EVENING AND PERSISTED FOR A FEW HOURS BEFORE DISSIPATING. OTHERWISE...CONVECTION HAS BEEN FOCUSED FURTHER WEST EARLY THIS MORNING IN THE VICINITY OF THE LOW LEVEL JET. SOME OF THIS ACTIVITY OVER EASTERN IA MAY ARRIVE ACROSS THE WESTERN CWA LATER THIS MORNING...LIKELY IN A DECAYING FORM. BUT OTHER THAN AN ISOLATED SHOWER...EXPECT THE NEXT SEVERAL HOURS TO BE MAINLY DRY. CONFIDENCE REGARDING THUNDERSTORM CHANCES THIS AFTERNOON INTO THIS EVENING IS LOW THOUGH THERE IS SOME CONSENSUS FOR DEVELOPMENT BY EARLY AFTERNOON ACROSS WESTERN/NORTHWEST IL FROM REMNANTS OF CONVECTION OVER EASTERN NEBRASKA/WESTERN IA. HOW FAR IT CONTINUES EAST OR NORTHEAST BEFORE WEAKENING IS ANOTHER UNCERTAINTY. MADE NO SIGNIFICANT CHANGES FOR TODAY MAINTAINING 30-40 POPS. TRENDS WILL NEED TO BE MONITORED THRU THE MORNING. DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES APPROACHING 2 INCHES WILL LEAD TO VERY HEAVY RAIN WITH ANY THUNDERSTORMS THAT DO DEVELOP AND POSSIBLY FLASH FLOODING...ESPECIALLY IF THE RAIN FALLS OVER HARDER HIT AREAS FROM FRIDAY MORNING. THE UPPER RIDGE THEN BUILDS ACROSS THE AREA TONIGHT AND SUNDAY AND PRECIP CHANCES LOOK BELOW MENTIONABLE FROM LATE TONIGHT THROUGH MONDAY MORNING. CAN/T COMPLETELY RULE OUT SOME ISOLATED ACTIVITY... IN PARTICULAR ON A LAKE BREEZE SUNDAY AFTERNOON. A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY WITH SOME DIFFERENCES AS TO HOW FAR SOUTH THIS BOUNDARY WILL SETTLE MONDAY AFTERNOON INTO MONDAY NIGHT. THIS WOULD LIKELY BE THE NEXT CHANCE OF THUNDERSTORMS WITH THE GEM/ECMWF BOTH PUSHING THE FRONT THROUGH MUCH OF THE CWA BY TUESDAY MORNING. THIS BOUNDARY THEN MEANDERS NEAR THE IL/WI BORDER INTO THURSDAY WITH THE POSSIBILITY OF A PROLONGED UNSETTLED PATTERN ACROSS THE AREA. CLOUD COVER/CONVECTION TODAY WILL LIKELY KEEP TEMPS IN THE 80S... THOUGH WITH THE URBAN AREAS STARTING FROM LOWER/MID 70S...ANY LONGER PERIOD OF SUNSHINE TODAY COULD ALLOW A FEW PLACES TO TAG 90. TEMPS WILL WARM A FEW DEGREES SUNDAY BUT SOUTHEASTERLY WINDS WILL KEEP THE LAKESHORE COOLER. MONDAY LOOKS TO BE THE BEST CHANCE FOR TEMPS INTO THE LOWER 90S CWA WIDE BUT WILL BE DEPENDENT ON CLOUD COVER AND TIMING/ARRIVAL OF ANY PRECIP. DEWPOINTS MAY LOWER A FEW DEGREES...BACK INTO THE MID/UPPER 60S ACROSS PARTS OF THE AREA SUNDAY. HEAT INDICES COULD RANGE FROM LOWER/MID 90S TO 100-105 FAR SOUTHWEST. DEWPOINTS THEN BACK INTO THE 70S EVERYWHERE MONDAY WITH HEAT INDICES CLOSER TO 100-105 MOST AREAS WITH STILL THE POTENTIAL TO REACH HEAT ADVISORY CRITERIA ACROSS THE FAR SOUTHERN CWA MONDAY AFTERNOON. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * TEMPORARY MVFR CIGS...ABOVE 1500FT...INTO THIS AFTERNOON. * EAST TO NORTHEAST WINDS THROUGH THE DAY WITH SPEEDS POSSIBLY APPROACHING 10 KT...WITH A CHANCE WINDS COULD GET DISRUPTED IN DIRECTION BY SHRA/TSRA. * TEMPORARY SHRA LIKELY WITHIN THE 19Z-22Z WINDOW WITH THE POSSIBILITY OF TSRA. * CHANCE FOR REDUCED CIGS/VSBY OVERNIGHT. MTF/MDB //DISCUSSION...UPDATED 16Z... AREA OF SHOWERS AND STORMS CONTINUE TO DRIVE ITSELF EASTWARD INTO NORTH CENTRAL IL AS OF 16Z. THIS SHOULD CONTINUE TO MOVE EAST...WITH AN EXPECTATION OF SOME DISSIPATION IN COVERAGE. THAT SAID...INTENSITY MAY ACTUALLY START TO INCREASE FURTHER EAST AS THE AREA MOVES INTO MORE UNSTABLE AIR. SO MAY NEED TO ADD TSRA MENTION TO CHICAGOLAND TAF SITES. MTF PREV DISCUSSION...UPDATED 12Z... WEAK LOW LEVEL FLOW FROM LAKE MICHIGAN COMBINED WITH THE VERY MOIST AIRMASS HAS ALLOWED STRATUS/FOG TO SLOWLY PUSH INLAND THIS MORNING. WITH ABUNDANT CIRRUS OVERHEAD WITH MORE UPSTREAM FROM CONVECTION ACROSS IOWA IMPROVEMENT MAY BE VERY SLOW THIS MORNING SO ADJUSTMENTS MAY BE NEEDED OVER THE NEXT FEW HOURS. WITH GYY/MDW/RFD BEING ON THE FRINGES OF THE IFR IMPROVEMENT MAY BE STEADIER THERE WITH ORD/DPA LIKELY BEING THE SLOWEST. DO EXPECT THAT VFR WILL RETURN HOWEVER. EASTERLY WINDS WILL BE IN PLACE THROUGH THE DAY WITH SPEEDS EXPECTED TO BE UNDER 10 KT. SPOTTY CONVECTION HAS BEEN FESTERING OVER FAR EASTERN IOWA AHEAD OF A MUCH LARGER COMPLEX ACROSS CENTRAL IOWA. THIS ACTIVITY IS MOVING NORTHEASTWARD BUT STEERING FLOW WOULD TAKE IT MORE EASTERLY THOUGH AT LEAST SOME DECAY IS POSSIBLE IN THE NEAR TERM. HAVE LOW CONFIDENCE IN HOW CONVECTION PLAYS OUT THE REST OF THE DAY BUT AT LEAST SCATTERED TSRA IS POSSIBLE AS THE PARENT FORCING DRIFTS TOWARD THE AREA LATER TODAY. THIS POINTS TO THE AFTERNOON/EVENING BEING THE MOST LIKELY PERIOD FOR STORMS BUT THE BEST CHANCES MAY BE FOCUSED WEST OF THE TERMINALS. GIVEN THE UNCERTAINTY WILL KEEP THE TAFS DRY FOR NOW BUT EXPECT THAT RFD MAY NEED A MENTION OF TSRA ADDED BEFORE TOO LONG. WITH CONTINUED WEAK FLOW AND HIGH HUMIDITY MORE FOG AND STRATUS WILL BE POSSIBLE TONIGHT. MDB //ORD AND MDW CONFIDENCE...UPDATED 16Z... * MEDIUM-HIGH IN OCCASIONAL MVFR CIGS. * MEDIUM IN WIND DIRECTION AND SPEED. * MEDIUM IN SHRA AND LOW IN TSRA OCCURRING AT THE AIRFIELDS. * MEDIUM THAT THERE WILL BE SOME SORT OF CIG/VSBY REDUCTION TONIGHT. MTF/MDB //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MDB && .MARINE... 340 AM CDT BROAD LOW PRESSURE REMAINS ACROSS THE MID MISSISSIPPI RIVER VALLEY THIS MORNING WHILE STRONGER LOW PRESSURE ORGANIZES OVER THE CENTRAL HIGH PLAINS. AN UPPER LOW SPINNING OVER THE NORTHWEST U.S. WILL HELP KICK THE HIGH PLAINS LOW NORTHWARD INTO SUNDAY WHILE HIGH PRESSURE MOVES FROM QUEBEC TO NEW ENGLAND AND THE MID-ATLANTIC STATES. EAST TO NORTHEAST WINDS WILL CONTINUE ACROSS LAKE MICHIGAN TODAY BUT WILL SHIFT TO THE SOUTHEAST INTO SUNDAY...WITH SPEEDS INCREASING MODESTLY. THE MAIN TRACK OF LOW PRESSURE WILL REMAIN OFF TO THE NORTHWEST OF THE LAKE INTO THE MIDDLE OF NEXT WEEK WHICH WILL KEEP A SOUTHERLY WIND GOING...THOUGH SOUTHERN AREAS MAY SEE WINDS SHIFT ONSHORE EACH AFTERNOON WHERE THE PRESSURE GRADIENT IS WEAKER. A FRONTAL BOUNDARY IS EXPECTED TO DROP OVER NORTHERN PARTS OF THE LAKE TOWARD MIDWEEK WHICH WOULD LEAD TO EAST OR NORTHEAST WINDS ACROSS THE NORTH WITH SOUTHERLY WINDS CONTINUING SOUTH. MEDIUM RANGE GUIDANCE CONFLICTS WITH HOW QUICKLY THIS FRONT MOVES ACROSS THE LAKE AND THE STRENGTH OF COLD AIR BEHIND IT DURING THE MIDDLE OF NEXT WEEK LEADING TO LOW FORECAST CONFIDENCE BY THAT TIME. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...DENSE FOG ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
959 AM CDT SAT AUG 23 2014 .DISCUSSION... 959 AM CDT THE FORECAST HAS BEEN UPDATED TO REFLECT GREATER CLOUD COVER AREAWIDE AND HIGHER POPS ACROSS MAINLY NORTH CENTRAL ILLINOIS DURING THE EARLY-MID AFTERNOON. A BROAD MESOSCALE CONVECTIVE SYSTEM WITH A LINE OF STORMS ON ITS FRONT EDGE IS CURRENTLY ADVANCING EAST OVER THE MISSISSIPPI RIVER AND FAR WESTERN ILLINOIS. THIS CONTINUES TO HOLD TOGETHER WELL WITH ONLY SUBTLE CLOUD TOP WARMING AND NO FADE IN LIGHTNING ACTIVITY OVER THE PAST COUPLE HOURS. THIS COMPLEX HAS BEEN ONGOING FOR OVER NINE HOURS SO NOT SURPRISED TO SEE THAT THE RADAR LOOP INDICATES THE LIKELY PRESENCE OF A CONVECTIVELY-INDUCED VORTICITY MAXIMUM /MCV/ IN FAR EASTERN IA. THIS WITH A COLD POOL IS HELPING TO USHER PUSH THE STORMS MORE EASTWARD THAN THE NORTHEAST MOVEMENT OF THE PARENT SHORTWAVE WOULD INDICATE. DESPITE WHAT SHOULD BE A GRADUAL FACE INTO THE EARLY AFTERNOON WITH THE UPPER SUPPORT MOVING NORTHEAST AND A DECAYING LOW-LEVEL JET PER PROFILERS...2.2 INCH PWAT AIR /99TH PERCENTILE/ AHEAD OF THE MCV WILL LIKELY SUPPORT SHOWERS AND SOME STORMS INTO NORTH CENTRAL ILLINOIS BETWEEN NOON AND 3 PM. STILL SEEING SOME EMBEDDED HOURLY PRECIP REPORTS OF A HALF TO ONE INCH WITH THIS...AND SOME OF THIS EFFICIENCY COULD CERTAINLY OCCUR ALONG AND WEST OF I-39 DURING THE EARLY AFTERNOON. UNDER THE INFLUENCE OF WEAK UPPER LEVEL FLOW...THE MCV IS FORECAST BY THE RAP AND NAM TO CONTINUE TO SLOW AS IT MOVES INTO NORTH CENTRAL IL. DESTABILIZATION AHEAD OF IT MAY SUPPORT ISOLATED OR SCATTERED SHOWERS/STORMS LATER THIS AFTERNOON FURTHER EAST TOWARD CHICAGO AND THE I-57 CORRIDOR INTO NORTHWEST INDIANA...BUT CONFIDENCE ON THIS IS LOW AS ANVIL SHIELD WILL INHIBIT THE RATE OF WARMTH...WITH MOST GUIDANCE INDICATING THE PRESENCE OF A CAP AND LOW-LEVEL FLOW OFF THE LAKE IN FAR NORTHEAST IL. MINOR TWEAKS MADE TO HOURLY TEMPERATURES AND DEW POINTS. MTF && .PREV DISCUSSION... 327 AM...FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES/TIMING THROUGH THE PERIOD ALONG WITH HIGH TEMPERATURES/HEAT INDICES THROUGH MONDAY. AREAS OF FOG CONTINUE TO DEVELOP WITH VISIBILITIES DROPPING UNDER 1SM IN A FEW LOCATIONS. NOT EXPECTING WIDESPREAD DENSE FOG THIS MORNING BUT WILL NEED TO MONITOR OBS OVER THE NEXT FEW HOURS. THE FOG WILL LIFT THIS MORNING BUT WITH LITTLE CHANGE TO THE AIRMASS FOG WILL BE POSSIBLE AGAIN TONIGHT INTO SUNDAY MORNING. A FEW SHOWERS DEVELOPED ACROSS NORTHERN LAKE COUNTY IN NORTHEAST IL LATE FRIDAY EVENING AND PERSISTED FOR A FEW HOURS BEFORE DISSIPATING. OTHERWISE...CONVECTION HAS BEEN FOCUSED FURTHER WEST EARLY THIS MORNING IN THE VICINITY OF THE LOW LEVEL JET. SOME OF THIS ACTIVITY OVER EASTERN IA MAY ARRIVE ACROSS THE WESTERN CWA LATER THIS MORNING...LIKELY IN A DECAYING FORM. BUT OTHER THAN AN ISOLATED SHOWER...EXPECT THE NEXT SEVERAL HOURS TO BE MAINLY DRY. CONFIDENCE REGARDING THUNDERSTORM CHANCES THIS AFTERNOON INTO THIS EVENING IS LOW THOUGH THERE IS SOME CONSENSUS FOR DEVELOPMENT BY EARLY AFTERNOON ACROSS WESTERN/NORTHWEST IL FROM REMNANTS OF CONVECTION OVER EASTERN NEBRASKA/WESTERN IA. HOW FAR IT CONTINUES EAST OR NORTHEAST BEFORE WEAKENING IS ANOTHER UNCERTAINTY. MADE NO SIGNIFICANT CHANGES FOR TODAY MAINTAINING 30-40 POPS. TRENDS WILL NEED TO BE MONITORED THRU THE MORNING. DEWPOINTS IN THE 70S AND PRECIPITABLE WATER VALUES APPROACHING 2 INCHES WILL LEAD TO VERY HEAVY RAIN WITH ANY THUNDERSTORMS THAT DO DEVELOP AND POSSIBLY FLASH FLOODING...ESPECIALLY IF THE RAIN FALLS OVER HARDER HIT AREAS FROM FRIDAY MORNING. THE UPPER RIDGE THEN BUILDS ACROSS THE AREA TONIGHT AND SUNDAY AND PRECIP CHANCES LOOK BELOW MENTIONABLE FROM LATE TONIGHT THROUGH MONDAY MORNING. CAN/T COMPLETELY RULE OUT SOME ISOLATED ACTIVITY... IN PARTICULAR ON A LAKE BREEZE SUNDAY AFTERNOON. A FRONTAL BOUNDARY WILL MOVE ACROSS THE UPPER MIDWEST SUNDAY NIGHT INTO MONDAY WITH SOME DIFFERENCES AS TO HOW FAR SOUTH THIS BOUNDARY WILL SETTLE MONDAY AFTERNOON INTO MONDAY NIGHT. THIS WOULD LIKELY BE THE NEXT CHANCE OF THUNDERSTORMS WITH THE GEM/ECMWF BOTH PUSHING THE FRONT THROUGH MUCH OF THE CWA BY TUESDAY MORNING. THIS BOUNDARY THEN MEANDERS NEAR THE IL/WI BORDER INTO THURSDAY WITH THE POSSIBILITY OF A PROLONGED UNSETTLED PATTERN ACROSS THE AREA. CLOUD COVER/CONVECTION TODAY WILL LIKELY KEEP TEMPS IN THE 80S... THOUGH WITH THE URBAN AREAS STARTING FROM LOWER/MID 70S...ANY LONGER PERIOD OF SUNSHINE TODAY COULD ALLOW A FEW PLACES TO TAG 90. TEMPS WILL WARM A FEW DEGREES SUNDAY BUT SOUTHEASTERLY WINDS WILL KEEP THE LAKESHORE COOLER. MONDAY LOOKS TO BE THE BEST CHANCE FOR TEMPS INTO THE LOWER 90S CWA WIDE BUT WILL BE DEPENDENT ON CLOUD COVER AND TIMING/ARRIVAL OF ANY PRECIP. DEWPOINTS MAY LOWER A FEW DEGREES...BACK INTO THE MID/UPPER 60S ACROSS PARTS OF THE AREA SUNDAY. HEAT INDICES COULD RANGE FROM LOWER/MID 90S TO 100-105 FAR SOUTHWEST. DEWPOINTS THEN BACK INTO THE 70S EVERYWHERE MONDAY WITH HEAT INDICES CLOSER TO 100-105 MOST AREAS WITH STILL THE POTENTIAL TO REACH HEAT ADVISORY CRITERIA ACROSS THE FAR SOUTHERN CWA MONDAY AFTERNOON. CMS && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * MVFR VISIBILITY AND CIG IMPROVING BY 15Z-16Z. * EAST TO NORTHEAST WINDS THROUGH THE DAY WITH SPEEDS POSSIBLY APPROACHING 10 KT. * LOW CHANCE FOR SHRA/TSRA...ESPECIALLY LATE THIS AFTERNOON AND EARLY THIS EVE. * CHANCE FOR REDUCED CIGS/VSBY OVERNIGHT. MTF/MDB //DISCUSSION...UPDATED 14Z... CIGS AND VISBYS HAVE RAPIDLY IMPROVED OVER ORD AND MDW...WITH THE GREATER RESTRICTIONS UNDER MORE STABILITY JUST TO THE NORTH OF ORD. REGARDING WIND SPEED THIS AFTERNOON...VAD WIND PROFILERS ARE INDICATING 10 KT OF EASTERLY FLOW AROUND 2000 FT WHICH WILL BE IN THE MIXED LAYER THIS AFTERNOON BASED ON TEMPERATURE FORECASTS. SO MAY SEE AT LEAST SPORADIC 10 KT WINDS 18Z AND AFTER. AS FOR STORMS NEAR THE MISSISSIPPI RIVER THIS SHOULD CONTINUE TO VERY SLOWLY FADE AS IT MOVES EAST-NORTHEAST. HAVE ADDED VCSH MENTION TO RFD AT THIS TIME AND MAY HAVE TO MENTION SHOWERS WITH TEMPORARY THUNDER DEPENDING ON OBSERVATIONAL AND LIGHTNING TRENDS. MTF PREV DISCUSSION...UPDATED 12Z... WEAK LOW LEVEL FLOW FROM LAKE MICHIGAN COMBINED WITH THE VERY MOIST AIRMASS HAS ALLOWED STRATUS/FOG TO SLOWLY PUSH INLAND THIS MORNING. WITH ABUNDANT CIRRUS OVERHEAD WITH MORE UPSTREAM FROM CONVECTION ACROSS IOWA IMPROVEMENT MAY BE VERY SLOW THIS MORNING SO ADJUSTMENTS MAY BE NEEDED OVER THE NEXT FEW HOURS. WITH GYY/MDW/RFD BEING ON THE FRINGES OF THE IFR IMPROVEMENT MAY BE STEADIER THERE WITH ORD/DPA LIKELY BEING THE SLOWEST. DO EXPECT THAT VFR WILL RETURN HOWEVER. EASTERLY WINDS WILL BE IN PLACE THROUGH THE DAY WITH SPEEDS EXPECTED TO BE UNDER 10 KT. SPOTTY CONVECTION HAS BEEN FESTERING OVER FAR EASTERN IOWA AHEAD OF A MUCH LARGER COMPLEX ACROSS CENTRAL IOWA. THIS ACTIVITY IS MOVING NORTHEASTWARD BUT STEERING FLOW WOULD TAKE IT MORE EASTERLY THOUGH AT LEAST SOME DECAY IS POSSIBLE IN THE NEAR TERM. HAVE LOW CONFIDENCE IN HOW CONVECTION PLAYS OUT THE REST OF THE DAY BUT AT LEAST SCATTERED TSRA IS POSSIBLE AS THE PARENT FORCING DRIFTS TOWARD THE AREA LATER TODAY. THIS POINTS TO THE AFTERNOON/EVENING BEING THE MOST LIKELY PERIOD FOR STORMS BUT THE BEST CHANCES MAY BE FOCUSED WEST OF THE TERMINALS. GIVEN THE UNCERTAINTY WILL KEEP THE TAFS DRY FOR NOW BUT EXPECT THAT RFD MAY NEED A MENTION OF TSRA ADDED BEFORE TOO LONG. WITH CONTINUED WEAK FLOW AND HIGH HUMIDITY MORE FOG AND STRATUS WILL BE POSSIBLE TONIGHT. MDB //ORD AND MDW CONFIDENCE...UPDATED 14Z... * HIGH IN CIGS AND VISIBILITY IMPROVING THROUGH MID-MORNING. * HIGH IN WIND DIRECTION AND MEDIUM IN WIND SPEED FORECAST THROUGH TODAY. * MEDIUM THAT POTENTIAL FOR SHRA/TSRA IS LOW THROUGH THE DAY. * MEDIUM THAT THERE WILL BE SOME SORT OF CIG/VSBY REDUCTION TONIGHT. MTF/MDB //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT...MVFR POSSIBLE. MONDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHRA/TSRA WITH OCCASIONAL MVFR. FRIDAY...VFR WITH SLIGHT CHANCE TSRA. MDB && .MARINE... 340 AM CDT BROAD LOW PRESSURE REMAINS ACROSS THE MID MISSISSIPPI RIVER VALLEY THIS MORNING WHILE STRONGER LOW PRESSURE ORGANIZES OVER THE CENTRAL HIGH PLAINS. AN UPPER LOW SPINNING OVER THE NORTHWEST U.S. WILL HELP KICK THE HIGH PLAINS LOW NORTHWARD INTO SUNDAY WHILE HIGH PRESSURE MOVES FROM QUEBEC TO NEW ENGLAND AND THE MID-ATLANTIC STATES. EAST TO NORTHEAST WINDS WILL CONTINUE ACROSS LAKE MICHIGAN TODAY BUT WILL SHIFT TO THE SOUTHEAST INTO SUNDAY...WITH SPEEDS INCREASING MODESTLY. THE MAIN TRACK OF LOW PRESSURE WILL REMAIN OFF TO THE NORTHWEST OF THE LAKE INTO THE MIDDLE OF NEXT WEEK WHICH WILL KEEP A SOUTHERLY WIND GOING...THOUGH SOUTHERN AREAS MAY SEE WINDS SHIFT ONSHORE EACH AFTERNOON WHERE THE PRESSURE GRADIENT IS WEAKER. A FRONTAL BOUNDARY IS EXPECTED TO DROP OVER NORTHERN PARTS OF THE LAKE TOWARD MIDWEEK WHICH WOULD LEAD TO EAST OR NORTHEAST WINDS ACROSS THE NORTH WITH SOUTHERLY WINDS CONTINUING SOUTH. MEDIUM RANGE GUIDANCE CONFLICTS WITH HOW QUICKLY THIS FRONT MOVES ACROSS THE LAKE AND THE STRENGTH OF COLD AIR BEHIND IT DURING THE MIDDLE OF NEXT WEEK LEADING TO LOW FORECAST CONFIDENCE BY THAT TIME. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...DENSE FOG ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 3 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
735 PM EDT SUN AUG 24 2014 .SYNOPSIS... ISSUED AT 339 PM EDT SUN AUG 24 2014 AN UPPER LEVEL RIDGE WILL PROVIDE DRY CONDITIONS TO THE REGION TONIGHT. WARM AND HUMID AIR WILL BE DRAWN NORTHWARD ACROSS THE REGION TONIGHT INTO MONDAY IN ADVANCE OF AN UPPER LEVEL DISTURBANCE TRACKING OUT OF THE PLAINS. AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE ON MONDAY...BUT A FRONTAL BOUNDARY ASSOCIATED WITH THIS DISTURBANCE WILL INCREASE THE CHANCE OF SHOWERS AND THUNDERSTORMS BY TUESDAY. LOW TEMPERATURES TONIGHT WILL DROP INTO THE MID AND UPPER 60S. HIGH TEMPERATURES ON MONDAY WILL RANGE FROM THE MID 80S IN CENTRAL LOWER MICHIGAN...TO THE LOWER 90S ACROSS NORTHEAST ILLINOIS. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 339 PM EDT SUN AUG 24 2014 MID/UPPER LEVEL RIDGING TO PERSIST ACROSS THE REGION TONIGHT...WITH PRIMARY SHORT WAVE TRACK FROM THE NORTHERN/CENTRAL PLAINS INTO THE WESTERN/NORTHERN GREAT LAKES. AS HAS BEEN THE CASE OVER THE PAST FEW DAYS...EASTERLY FLOW REGIME HAS BEEN CONDUCIVE FOR NARROW ZONES OF WEAK CONVERGENCE...THE MOST DISTINCT THIS AFTERNOON ROUGHLY FROM KEKM TO JUST NORTH OF KAOH. THE MOST UNSTABLE CONDITIONS ARE ACROSS THE SOUTHWEST PORTIONS OF THE CWA. LITTLE IN THE WAY OF ANY SYNOPTIC FORCING FOR VERTICAL MOTION NOTED THIS AFTERNOON DUE TO PERSISTENCE OF UPPER RIDGING...ALTHOUGH AN ISOLATED SHOWER OR STORM MAY TRY TO DEVELOP ALONG THE AFOREMENTIONED CONVERGENCE ZONE WHERE SOME SLIGHTLY BETTER GROWTH HAS BEEN NOTED IN AFTERNOON CU FIELD. CONFIDENCE IN OCCURRENCE AND EXPECTED VERY LIMITED COVERAGE TO ANY CONVECTIVE DEVELOPMENT PRECLUDES ANY ZFP MENTION. A SIMILAR SETUP IN STAGNANT PATTERN TONIGHT SHOULD YIELD SOME PATCHY FOG AND STRATUS THROUGH EARLY MONDAY MORNING. UPPER LEVEL LOW CENTERED ACROSS THE NORTHERN HIGH PLAINS WILL LIFT NORTHEAST INTO ONTARIO BY MONDAY EVENING. AN AXIS OF STRONGER SOUTHWESTERLY LOW LEVEL FLOW WILL ALLOW FOR STRONG MOISTURE TRANSPORT FROM THE MID MS VALLEY INTO THE NORTHERN GREAT LAKES TONIGHT WHERE BEST CHANCES OF SHOWERS AND THUNDERSTORMS WILL RESIDE. EVOLUTION OF THIS PATTERN WILL ALLOW FOR SLIGHT DEAMPLIFICATION OF UPPER RIDGING ACROSS THE GREAT LAKES...AND NOT COMPLETELY OUT OF THE QUESTION A REMNANT CONVECTIVE VORT COULD DROP SOUTHEAST INTO THE SOUTHERN GREAT LAKES DURING THE DAY MONDAY. LOW LEVEL ANTICYCLONE SHIFTING SOUTHEAST ACROSS THE MID ATLANTIC STATES SHOULD ALLOW FOR SOME LOW LEVEL VEERING AND WARM/MOIST ADVECTION BACK INTO LOCAL AREA...SETTING UP VERY UNSTABLE CONDITIONS FOR MONDAY. OUTSIDE OF REMNANT FORCING FROM UPSTREAM CONVECTION TO THE NORTHWEST...NOT MUCH TO KEY IN ON FOR FORCING MONDAY. HOWEVER...GIVEN SLIGHTLY SUPPRESSED NATURE OF UPPER RIDGE...AND VERY UNSTABLE CONDITIONS...DID INCLUDE SOME SLIGHT CHANCE TSRA POPS ACROSS MAINLY NORTHERN HALF INTO EASTERN PORTIONS OF FORECAST AREA FOR MONDAY. WITH THE RETURN WARM/MOIST ADVECTION TONIGHT INTO EARLY MONDAY...SFC DEW POINTS SHOULD CREEP BACK INTO THE LOWER TO MID 70S WHICH WOULD YIELD PEAK AFTERNOON HEAT INDICES FROM THE MID TO UPPER 90S WEST...TO THE LOWER 90S EAST ON MONDAY. AREAS ACROSS THE FAR WEST/SOUTHWEST COULD CREEP CLOSE TO HEAT ADVISORY CRITERIA...BUT GIVEN MARGINAL NATURE AND STILL SOME QUESTIONS SURROUNDING LOW STRATUS/HIGH CLOUD EVOLUTION TONIGHT INTO EARLY MONDAY...WILL HOLD OFF FOR NOW. && .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 339 PM EDT SUN AUG 24 2014 A RIDGE FLATTENING SHORTWAVE TROUGH PROPAGATING NORTHEAST INTO ONTARIO/WESTERN QUEBEC TO START THE PERIOD WILL HELP FORCE A WEAK FRONTAL BOUNDARY SOUTH INTO THE AREA BY LATER TUESDAY-WEDNESDAY. MOIST/UNSTABLE ENVIRONMENT ALONG/SOUTH OF BOUNDARY SUPPORT GOING CHANCE POPS FOR CONVECTION...ALTHOUGH FORCING MAY NOT BE STRONG ENOUGH ON TUESDAY TO OVERCOME CAPPING INVERSION WITH THE LOCAL AREA DISPLACED SOUTH OF STRONGER/MORE PERTURBED WESTERLY FLOW. IF/WHERE CONVECTION FIRES HEAVY RAIN WILL LIKELY BECOME THE PRIMARY CONCERN GIVEN WEAK FLOW AND ~2" PWAT POOLING INVOF BOUNDARY. 00/12Z MODEL ITERATIONS OVERALL TRENDED TOWARD A DRIER SOLUTION LATER WEDNESDAY INTO THURSDAY...ESPECIALLY ALONG/NORTH OF HWY 30...WITH MORE PRONOUNCED NORTHEAST CONUS UPPER TROUGHING ALLOWING A LOW LEVEL ANTICYCLONE TO BUILD INTO THE GREAT LAKES REGION. THIS WOULD HELP STALL THE EASTWARD PROGRESSION OF A ROCKIES SHORTWAVE AND PUSH THE ACTIVE INSTABILITY GRADIENT SOUTH OF THE IWX CWA. GIVEN THESE TRENDS OPTED TO LOWER POPS...WITH A COUPLE DAYS OF COOLER/LESS HUMID WEATHER POSSIBLE. LITTLE TO NO CHANGE FRIDAY AND BEYOND AS GUIDANCE CONTINUE TO STRUGGLE WITH TIMING/SPEED OF A LONGER WAVELENGTH TROUGH MODELED TO PROPAGATE EAST THROUGH THE MIDWEST/GREAT LAKES. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 728 PM EDT SUN AUG 24 2014 A SUBTLE SHORT WAVE OVER A PERSISTENT AND SUBTLE SURFACE BOUNDARY ALONG WITH WEAK THETA E ADVECTION WAS LEADING TO ISOLATED SHOWERS BETWEEN KSBN AND KFWA EARLY THIS EVENING. RUC SOUNDINGS INDICATE A CAP IN PLACE ABOVE 800MB AND THIS HAS SEEMED TO LIMIT DEVELOPMENT ALONG WITH MID LEVEL RIDGE. THIS WEAK ACTIVITY LOOKS TO REMAIN EAST OF KSBN AND JUST NORTH OF KFWA SO WILL BEGIN THE PERIOD QUIET WITH VFR CONDITIONS. MOIST BOUNDARY LAYER AND WINDS UNDER 5 KNOTS OVERNIGHT MAY ALLOW FOR PATCHY BR AND STRATUS SO KEPT A TEMPO GROUP GOING FOR THIS. UPSTREAM CONVECTION NOW DEVELOPING OVER MN TO IA EXPECTED TO GROW OVERNIGHT. COMPOSITE OUTFLOW AND/OR MCV INDICATED BY SOME MODELS OF MAKING A RUN TOWARD OUR AREA MONDAY MORNING BUT IN A WEAKENED STATE. WILL KEEP THIS OUT OF POINT TAFS AT THIS TIME GIVEN SMALL CHANCES AND PROBLEMS MODELING CONVECTION. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...MARSILI SHORT TERM...MARSILI LONG TERM...STEINWEDEL AVIATION...LASHLEY VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
216 PM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 401 AM EDT SAT AUG 23 2014 WARM AND HUMID CONDITIONS WILL PERSIST FOR ONE MORE DAY BEFORE A BRIEF BREAK IN THE STICKY CONDITIONS ARRIVES TONIGHT INTO SUNDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND EVENING WITH CHANCES DIMINISHING TONIGHT. DRY CONDITIONS ARE EXPECTED UNTIL TUESDAY WHEN A COLD FRONT BEGINS TO APPROACH THE AREA. HIGHS WILL BE IN THE 80S WITH LOWS IN THE 60S THE NEXT COUPLE OF DAYS. && .UPDATE... ISSUED AT 1116 AM EDT SAT AUG 23 2014 FOG HAS DISSIPATED ACROSS MOST OF THE AREA THIS MORNING...WITH THE EXCEPTION BEING JUST SOME PATCHY 2-5 MILE VISIBILITIES WHERE STRATUS DECK HAS PERSISTED THE LONGEST FROM SOUTHWEST LOWER MICHIGAN SOUTHEASTWARD TO LIMA OHIO. MCS ACROSS EASTERN IOWA/NORTHWEST ILLINOIS WILL BE THE NEXT ITEM OF CONCERN TO ADDRESS FOR THE LOCAL AREA. CORFIDI VECTORS SUPPORT MORE OF AN EAST/SOUTH PROPAGATION THIS AFTERNOON...WITH ORIENTATION OF STRONGEST INSTABILITY AXIS ALSO FAVORING GENERAL PROPAGATION/DEVELOPMENT TO THE SOUTHEAST...CLIPPING ESPECIALLY SOUTHWEST PORTIONS OF THE AREA. HAVE INCREASED TO MID RANGE CHANCE POPS ACROSS THE FAR SOUTHWEST TO ACCOUNT FOR THIS...WHILE MAINTAINING OVERALL SOUTHWEST TO NORTHEAST POP GRADIENT FROM PREVIOUS FORECAST. SEVERE WEATHER POTENTIAL STILL APPEARS TO BE QUITE LOW WITH ANY LOW END/ISOLD RISK LIKELY BEING CONFINED TO RICHER LOW LEVEL MOISTURE AXIS ACROSS SOUTHWEST PORTIONS OF THE AREA. WHILE INSTABILITY WILL BE MAXIMIZED ACROSS THE SOUTHWEST...THIS MAY REPRESENT A MINIMUM IN DEEP LAYER SHEAR. ONLY CAVEAT TO THIS WOULD BE FOR SMALLER SCALE AREA OF LOCALLY ENHANCED SHEAR ASSOCIATED WITH CONVECTIVELY ENHANCED VORT MAX EMANATING FROM IOWA/ILLINOIS CONVECTION. GIVEN HEAVY RAINFALL OVER PAST FEW DAYS ACROSS THE SOUTHWEST...WILL ESPECIALLY HAVE TO MONITOR FOR ANY STORMS CAPABLE OF LOCALIZED HEAVIER RAINFALL. TEMPS APPEAR TO BE IN GOOD SHAPE WITH JUST SOME MINOR TWEAKS TO MORNING DIURNAL CURVE TO ACCOUNT FOR LINGERING STRATUS DECK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 401 AM EDT SAT AUG 23 2014 SEVERAL SMALLER ITEMS TO TRY TO SORT OUT FOR THE FORECAST. FIRST OFF WILL BE COMBINATION OF MOIST LOW LEVEL AIR MASS AND MOSTLY CLEAR SKIES ALLOWING FOR STRATUS/FOG DEVELOPMENT ACROSS THE AREA. OBSERVATIONS HAVE BEEN SHOWING THIS ALREADY TAKING PLACE...WITH ISSUES EXPECTED TO PERSIST THROUGH AT LEAST 10 AM BEFORE SUFFICIENT MIXING OCCURS TO HELP BREAK THINGS UP. NEXT UP WILL BE ATTEMPT TO ADVECT IN SOMEWHAT DRIER AIR FROM THE NE AGAINST THE PERSISTENT BUT WEAK SW FLOW ACROSS MUCH OF THE WESTERN GREAT LAKES. A SUBTLE BOUNDARY WAS LOCATED FROM S LK MICHIGAN TO VICINITY OF FT WAYNE. THIS FEATURE...COMBINED WITH WHAT APPEARS TO BE A MID LEVEL DISTURBANCE OR SERIES OF GRAVITY WAVES...HELPED SPARK SMALL AREAS OF SLOW MOVING SHOWERS AND STORMS THAT HAVE SINCE DISSIPATED. LOCATIONS ALONG AND SW OF THIS BOUNDARY WILL SEE A CHANCE FOR HIT OR MISS SHOWERS/STORMS THIS AFTERNOON/EVE IF SUFFICIENT HEATING CAN TAKE PLACE. WARM AND HUMID CONDITIONS WILL REMAIN UNTIL THE NE FLOW CAN STRENGTHEN SLIGHTLY AS RIDGE INFLUENCE BRIEFLY RELAXES WITH DEWPOINTS DROPPING INTO THE MID 60S (LOW 60S NE). A FEW RUNS OF THE RUC TRY TO BRING THIS DRIER AIR A BIT FASTER IN NE SECTIONS THAT CURRENTLY DEPICTED. GIVEN WEAK NATURE OF SLOW...THINK SLOWER IS BETTER AT THIS POINT UNTIL DEGREE OF MIXING CAN BE DETERMINED. AS A RESULT...HIGHS SHOULD REACH THE MID 80S WITH HEAT INDICES NEAR OR JUST INTO THE 90S. NE FLOW WILL PUSH AXIS OF BEST PRECIPITATION POTENTIAL TO THE SW OF THE REGION DURING THE EVENING HOURS...LEADING TO WHAT SHOULD BE A PLEASANTLY DRY NIGHT AS LOWS DROP INTO THE MID 60S TO NEAR 70. HAVE KEPT A LINGERING SLGT CHC OF SHOWERS IN FAR SW AREAS EARLY EVENING BUT THEN REMOVED ALL MENTION OF PRECIPITATION AFTER 3Z. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 401 AM EDT SAT AUG 23 2014 STRONG SHRTWV MOVG THROUGH NRN NEVADA THIS MORNING EXPECTED TO LIFT SLOWLY NE THROUGH THE NRN HIGH PLAINS SUNDAY WITH DOWNSTREAM RIDGE MOVG EAST ACROSS OUR CWA. LACK OF FORCING AND A LITTLE DRIER AIR ADVECTING INTO OUR AREA IN THE H925-H85 LAYER DUE TO EASTERLY FLOW AROUND STRENGTHENING ANTICYCLONE OVER THE LWR GRTLKS SUGGESTS DRY CONDITIONS ACROSS OUR AREA. GOOD DEAL OF SUNSHINE SHOULD ALLOW MIXING UP TO NEAR H850 WHICH WOULD RESULT IN HIGHS IN THE M-U80S. NRN PLAINS SHRTWV EXPECTED TO MOVE EAST TO ONTARIO ON MONDAY. RIDGE OVER THE UPR GRTLKS WILL FLATTEN OUT IN RESPONSE BUT SHOULD HOLD STRONG IN OUR AREA KEEPING CONDITIONS DRY. TEMPS EXPECTED TO CONTINUE SLOW WARMING TREND AS WINDS VEER MORE SOUTHERLY WITH HIGHS IN THE U80S/L90S. ONTARIO SHRTWV EXPECTED TO SHEAR OUT AND LIFT ENE INTO QUEBEC TUE WITH TRAILING CDFNT SINKING SLOWLY SOUTH INTO OR CLOSE TO NRN PORTION OF OUR CWA BY WED MORNING. TSTMS SHOULD DEVELOP ALONG THE FRONT AND MAY PROPAGATE SE INTO UNSTABLE AIRMASS OVER OUR AREA... BUT CAPPING INVERSION MAKES THIS SCENARIO DOUBTFUL... SO JUST CONTD WITH LOW CHC POPS. TEMPS SHOULD REMAIN WELL ABOVE NORMAL WITH HIGHS AROUND 90 AND LOWS NEAR 70. MODEL SOLUTIONS DIVERGE SIGNIFICANTLY LATE WEEK WITH ECMWF/GEM SUGGESTING NEXT STRONG SHRTWV TO MOVE INTO MEAN WRN TROF WILL CUT-OFF OVER THE ROCKIES AND THEN MOVE SLOWLY EAST... WHILE GFS SUGGESTS A MORE PROGRESSIVE SCENARIO. IN EITHER CASE... LOW POPS STILL WARRANTED FOR WED-THU... WHILE GFS INDICATES COOLER/DRIER CONDITIONS WILL OVERSPREAD THE AREA BY FRIDAY. THIS SOLUTION IN BETTER AGREEMENT WITH GOING FCST AND GIVEN EXCESSIVE UNCERTAINTY WITH LARGE MODEL DIFFERENCES... STAYED CLOSE TO PREVIOUS FCST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 152 PM EDT SAT AUG 23 2014 CONVECTIVE COMPLEX ACROSS NORTHERN ILLINOIS HAS EXHIBITED SOME TREND TO SOUTHEAST PROPAGATION OVER THE LAST HOUR AND EXPECTING THIS OVERALL TREND TO PERSIST THROUGH THE REMAINDER OF THE AFTERNOON. WILL HAVE TO MONITOR FOR OUTFLOW ACCELERATING AHEAD OF THIS LINE TO POSSIBLY BE FOCUS FOR ADDITIONAL THUNDERSTORM DEVELOPMENT AT KSBN LATE THIS AFTERNOON. IN THE MEANTIME...WILL ALSO NEED TO MONITOR FOR POTENTIAL ISOLATED DEVELOPMENT ALONG WEAK LAKE BREEZE WHICH HAS FORMED...WITH CU BEING MORE VERTICALLY DEVELOPED RECENTLY TOWARD KMGC-KVPZ. SOME POTENTIAL OF THUNDER WILL EXIST AT KSBN INTO THE EVENING HOURS AS REMNANT VORT MAX FROM ILLINOIS CONVECTION DROPS SOUTHEAST THROUGH WESTERN INDIANA. WITH BEST NEAR TERM POTENTIAL OF STORMS SOUTH AND WEST OF TERMINALS...WILL HOLD OFF ON INCLUSION WTIH THE 18Z TAFS. SETUP DOES APPEAR FAVORABLE FOR FOG AND STRATUS TO REDEVELOP OVERNIGHT...AND HAVE CONTINUED TREND OF PREVIOUS ISSUANCE TO IFR/LOWER END MVFR CONDITIONS OVERNIGHT. SLIGHTLY DRIER AIR TO ADVECT EASTWARD ON SUNDAY AND MID LEVEL RIDGE BUILDING INTO THE AREA SHOULD TEND TO DISCOURAGE THUNDER CHANCES FOR SUNDAY...WITH EAST WINDS OF 10 KNOTS OR LESS CONTINUING. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...MARSILI SYNOPSIS...FISHER SHORT TERM...FISHER LONG TERM...JT AVIATION...MARSILI VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1134 AM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 401 AM EDT SAT AUG 23 2014 WARM AND HUMID CONDITIONS WILL PERSIST FOR ONE MORE DAY BEFORE A BRIEF BREAK IN THE STICKY CONDITIONS ARRIVES TONIGHT INTO SUNDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND EVENING WITH CHANCES DIMINISHING TONIGHT. DRY CONDITIONS ARE EXPECTED UNTIL TUESDAY WHEN A COLD FRONT BEGINS TO APPROACH THE AREA. HIGHS WILL BE IN THE 80S WITH LOWS IN THE 60S THE NEXT COUPLE OF DAYS. && .UPDATE... ISSUED AT 1116 AM EDT SAT AUG 23 2014 FOG HAS DISSIPATED ACROSS MOST OF THE AREA THIS MORNING...WITH THE EXCEPTION BEING JUST SOME PATCHY 2-5 MILE VISIBILITIES WHERE STRATUS DECK HAS PERSISTED THE LONGEST FROM SOUTHWEST LOWER MICHIGAN SOUTHEASTWARD TO LIMA OHIO. MCS ACROSS EASTERN IOWA/NORTHWEST ILLINOIS WILL BE THE NEXT ITEM OF CONCERN TO ADDRESS FOR THE LOCAL AREA. CORFIDI VECTORS SUPPORT MORE OF AN EAST/SOUTH PROPAGATION THIS AFTERNOON...WITH ORIENTATION OF STRONGEST INSTABILITY AXIS ALSO FAVORING GENERAL PROPAGATION/DEVELOPMENT TO THE SOUTHEAST...CLIPPING ESPECIALLY SOUTHWEST PORTIONS OF THE AREA. HAVE INCREASED TO MID RANGE CHANCE POPS ACROSS THE FAR SOUTHWEST TO ACCOUNT FOR THIS...WHILE MAINTAINING OVERALL SOUTHWEST TO NORTHEAST POP GRADIENT FROM PREVIOUS FORECAST. SEVERE WEATHER POTENTIAL STILL APPEARS TO BE QUITE LOW WITH ANY LOW END/ISOLD RISK LIKELY BEING FINED TO RICHER LOW LEVEL MOISTURE AXIS ACROSS SOUTHWEST PORTIONS OF THE AREA. WHILE INSTABILITY WILL BE MAXIMIZED ACROSS THE SOUTHWEST...THIS MAY REPRESENT A MINIMUM IN DEEP LAYER SHEAR. ONLY CAVEAT TO THIS WOULD BE FOR SMALLER SCALE AREA OF LOCALLY ENHANCED SHEAR ASSOCIATED WITH CONVECTIVELY ENHANCED VORT MAX EMANATING FROM IOWA/ILLINOIS CONVECTION. GIVEN HEAVY RAINFALL OVER PAST FEW DAYS ACROSS THE SOUTHWEST...WILL ESPECIALLY HAVE TO MONITOR FOR ANY STORMS CAPABLE OF LOCALIZED HEAVIER RAINFALL. TEMPS APPEAR TO BE IN GOOD SHAPE WITH JUST SOME MINOR TWEAKS TO MORNING DIURNAL CURVE TO ACCOUNT FOR LINGERING STRATUS DECK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 401 AM EDT SAT AUG 23 2014 SEVERAL SMALLER ITEMS TO TRY TO SORT OUT FOR THE FORECAST. FIRST OFF WILL BE COMBINATION OF MOIST LOW LEVEL AIR MASS AND MOSTLY CLEAR SKIES ALLOWING FOR STRATUS/FOG DEVELOPMENT ACROSS THE AREA. OBSERVATIONS HAVE BEEN SHOWING THIS ALREADY TAKING PLACE...WITH ISSUES EXPECTED TO PERSIST THROUGH AT LEAST 10 AM BEFORE SUFFICIENT MIXING OCCURS TO HELP BREAK THINGS UP. NEXT UP WILL BE ATTEMPT TO ADVECT IN SOMEWHAT DRIER AIR FROM THE NE AGAINST THE PERSISTENT BUT WEAK SW FLOW ACROSS MUCH OF THE WESTERN GREAT LAKES. A SUBTLE BOUNDARY WAS LOCATED FROM S LK MICHIGAN TO VICINITY OF FT WAYNE. THIS FEATURE...COMBINED WITH WHAT APPEARS TO BE A MID LEVEL DISTURBANCE OR SERIES OF GRAVITY WAVES...HELPED SPARK SMALL AREAS OF SLOW MOVING SHOWERS AND STORMS THAT HAVE SINCE DISSIPATED. LOCATIONS ALONG AND SW OF THIS BOUNDARY WILL SEE A CHANCE FOR HIT OR MISS SHOWERS/STORMS THIS AFTERNOON/EVE IF SUFFICIENT HEATING CAN TAKE PLACE. WARM AND HUMID CONDITIONS WILL REMAIN UNTIL THE NE FLOW CAN STRENGTHEN SLIGHTLY AS RIDGE INFLUENCE BRIEFLY RELAXES WITH DEWPOINTS DROPPING INTO THE MID 60S (LOW 60S NE). A FEW RUNS OF THE RUC TRY TO BRING THIS DRIER AIR A BIT FASTER IN NE SECTIONS THAT CURRENTLY DEPICTED. GIVEN WEAK NATURE OF SLOW...THINK SLOWER IS BETTER AT THIS POINT UNTIL DEGREE OF MIXING CAN BE DETERMINED. AS A RESULT...HIGHS SHOULD REACH THE MID 80S WITH HEAT INDICES NEAR OR JUST INTO THE 90S. NE FLOW WILL PUSH AXIS OF BEST PRECIPITATION POTENTIAL TO THE SW OF THE REGION DURING THE EVENING HOURS...LEADING TO WHAT SHOULD BE A PLEASANTLY DRY NIGHT AS LOWS DROP INTO THE MID 60S TO NEAR 70. HAVE KEPT A LINGERING SLGT CHC OF SHOWERS IN FAR SW AREAS EARLY EVENING BUT THEN REMOVED ALL MENTION OF PRECIPITATION AFTER 3Z. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 401 AM EDT SAT AUG 23 2014 STRONG SHRTWV MOVG THROUGH NRN NEVADA THIS MORNING EXPECTED TO LIFT SLOWLY NE THROUGH THE NRN HIGH PLAINS SUNDAY WITH DOWNSTREAM RIDGE MOVG EAST ACROSS OUR CWA. LACK OF FORCING AND A LITTLE DRIER AIR ADVECTING INTO OUR AREA IN THE H925-H85 LAYER DUE TO EASTERLY FLOW AROUND STRENGTHENING ANTICYCLONE OVER THE LWR GRTLKS SUGGESTS DRY CONDITIONS ACROSS OUR AREA. GOOD DEAL OF SUNSHINE SHOULD ALLOW MIXING UP TO NEAR H850 WHICH WOULD RESULT IN HIGHS IN THE M-U80S. NRN PLAINS SHRTWV EXPECTED TO MOVE EAST TO ONTARIO ON MONDAY. RIDGE OVER THE UPR GRTLKS WILL FLATTEN OUT IN RESPONSE BUT SHOULD HOLD STRONG IN OUR AREA KEEPING CONDITIONS DRY. TEMPS EXPECTED TO CONTINUE SLOW WARMING TREND AS WINDS VEER MORE SOUTHERLY WITH HIGHS IN THE U80S/L90S. ONTARIO SHRTWV EXPECTED TO SHEAR OUT AND LIFT ENE INTO QUEBEC TUE WITH TRAILING CDFNT SINKING SLOWLY SOUTH INTO OR CLOSE TO NRN PORTION OF OUR CWA BY WED MORNING. TSTMS SHOULD DEVELOP ALONG THE FRONT AND MAY PROPAGATE SE INTO UNSTABLE AIRMASS OVER OUR AREA... BUT CAPPING INVERSION MAKES THIS SCENARIO DOUBTFUL... SO JUST CONTD WITH LOW CHC POPS. TEMPS SHOULD REMAIN WELL ABOVE NORMAL WITH HIGHS AROUND 90 AND LOWS NEAR 70. MODEL SOLUTIONS DIVERGE SIGNIFICANTLY LATE WEEK WITH ECMWF/GEM SUGGESTING NEXT STRONG SHRTWV TO MOVE INTO MEAN WRN TROF WILL CUT-OFF OVER THE ROCKIES AND THEN MOVE SLOWLY EAST... WHILE GFS SUGGESTS A MORE PROGRESSIVE SCENARIO. IN EITHER CASE... LOW POPS STILL WARRANTED FOR WED-THU... WHILE GFS INDICATES COOLER/DRIER CONDITIONS WILL OVERSPREAD THE AREA BY FRIDAY. THIS SOLUTION IN BETTER AGREEMENT WITH GOING FCST AND GIVEN EXCESSIVE UNCERTAINTY WITH LARGE MODEL DIFFERENCES... STAYED CLOSE TO PREVIOUS FCST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 648 AM EDT SAT AUG 23 2014 FOG CAUSING WIDESPREAD LIFR CONDITIONS ACROSS NRN INDIANA EARLY THIS MORNING. DIURNAL HEATING SHOULD ALLOW CONDITIONS TO GRDLY IMPROVE TO VFR BY THIS AFTN. STNRY FRONT REMAINS DRAPED ACROSS THE AREA AND MAY PROVIDE A FOCUS FOR TSRA THIS AFTN... HWVR CHANCES TOO LOW TO MENTION IN THE TAFS. DRIER AIR EXPECTED TO MOVE INTO THE AREA FROM THE EAST TONIGHT... BUT STILL SHOULD BE SUFFICIENT RADIATIONAL COOLING FOR SOME MVFR VSBYS IN BR TOWARD DAYBREAK. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...MARSILI SYNOPSIS...FISHER SHORT TERM...FISHER LONG TERM...JT AVIATION...JT VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
655 AM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 401 AM EDT SAT AUG 23 2014 WARM AND HUMID CONDITIONS WILL PERSIST FOR ONE MORE DAY BEFORE A BRIEF BREAK IN THE STICKY CONDITIONS ARRIVES TONIGHT INTO SUNDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND EVENING WITH CHANCES DIMINISHING TONIGHT. DRY CONDITIONS ARE EXPECTED UNTIL TUESDAY WHEN A COLD FRONT BEGINS TO APPROACH THE AREA. HIGHS WILL BE IN THE 80S WITH LOWS IN THE 60S THE NEXT COUPLE OF DAYS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 401 AM EDT SAT AUG 23 2014 SEVERAL SMALLER ITEMS TO TRY TO SORT OUT FOR THE FORECAST. FIRST OFF WILL BE COMBINATION OF MOIST LOW LEVEL AIR MASS AND MOSTLY CLEAR SKIES ALLOWING FOR STRATUS/FOG DEVELOPMENT ACROSS THE AREA. OBSERVATIONS HAVE BEEN SHOWING THIS ALREADY TAKING PLACE...WITH ISSUES EXPECTED TO PERSIST THROUGH AT LEAST 10 AM BEFORE SUFFICIENT MIXING OCCURS TO HELP BREAK THINGS UP. NEXT UP WILL BE ATTEMPT TO ADVECT IN SOMEWHAT DRIER AIR FROM THE NE AGAINST THE PERSISTENT BUT WEAK SW FLOW ACROSS MUCH OF THE WESTERN GREAT LAKES. A SUBTLE BOUNDARY WAS LOCATED FROM S LK MICHIGAN TO VICINITY OF FT WAYNE. THIS FEATURE...COMBINED WITH WHAT APPEARS TO BE A MID LEVEL DISTURBANCE OR SERIES OF GRAVITY WAVES...HELPED SPARK SMALL AREAS OF SLOW MOVING SHOWERS AND STORMS THAT HAVE SINCE DISSIPATED. LOCATIONS ALONG AND SW OF THIS BOUNDARY WILL SEE A CHANCE FOR HIT OR MISS SHOWERS/STORMS THIS AFTERNOON/EVE IF SUFFICIENT HEATING CAN TAKE PLACE. WARM AND HUMID CONDITIONS WILL REMAIN UNTIL THE NE FLOW CAN STRENGTHEN SLIGHTLY AS RIDGE INFLUENCE BRIEFLY RELAXES WITH DEWPOINTS DROPPING INTO THE MID 60S (LOW 60S NE). A FEW RUNS OF THE RUC TRY TO BRING THIS DRIER AIR A BIT FASTER IN NE SECTIONS THAT CURRENTLY DEPICTED. GIVEN WEAK NATURE OF SLOW...THINK SLOWER IS BETTER AT THIS POINT UNTIL DEGREE OF MIXING CAN BE DETERMINED. AS A RESULT...HIGHS SHOULD REACH THE MID 80S WITH HEAT INDICES NEAR OR JUST INTO THE 90S. NE FLOW WILL PUSH AXIS OF BEST PRECIPITATION POTENTIAL TO THE SW OF THE REGION DURING THE EVENING HOURS...LEADING TO WHAT SHOULD BE A PLEASANTLY DRY NIGHT AS LOWS DROP INTO THE MID 60S TO NEAR 70. HAVE KEPT A LINGERING SLGT CHC OF SHOWERS IN FAR SW AREAS EARLY EVENING BUT THEN REMOVED ALL MENTION OF PRECIPITATION AFTER 3Z. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 401 AM EDT SAT AUG 23 2014 STRONG SHRTWV MOVG THROUGH NRN NEVADA THIS MORNING EXPECTED TO LIFT SLOWLY NE THROUGH THE NRN HIGH PLAINS SUNDAY WITH DOWNSTREAM RIDGE MOVG EAST ACROSS OUR CWA. LACK OF FORCING AND A LITTLE DRIER AIR ADVECTING INTO OUR AREA IN THE H925-H85 LAYER DUE TO EASTERLY FLOW AROUND STRENGTHENING ANTICYCLONE OVER THE LWR GRTLKS SUGGESTS DRY CONDITIONS ACROSS OUR AREA. GOOD DEAL OF SUNSHINE SHOULD ALLOW MIXING UP TO NEAR H850 WHICH WOULD RESULT IN HIGHS IN THE M-U80S. NRN PLAINS SHRTWV EXPECTED TO MOVE EAST TO ONTARIO ON MONDAY. RIDGE OVER THE UPR GRTLKS WILL FLATTEN OUT IN RESPONSE BUT SHOULD HOLD STRONG IN OUR AREA KEEPING CONDITIONS DRY. TEMPS EXPECTED TO CONTINUE SLOW WARMING TREND AS WINDS VEER MORE SOUTHERLY WITH HIGHS IN THE U80S/L90S. ONTARIO SHRTWV EXPECTED TO SHEAR OUT AND LIFT ENE INTO QUEBEC TUE WITH TRAILING CDFNT SINKING SLOWLY SOUTH INTO OR CLOSE TO NRN PORTION OF OUR CWA BY WED MORNING. TSTMS SHOULD DEVELOP ALONG THE FRONT AND MAY PROPAGATE SE INTO UNSTABLE AIRMASS OVER OUR AREA... BUT CAPPING INVERSION MAKES THIS SCENARIO DOUBTFUL... SO JUST CONTD WITH LOW CHC POPS. TEMPS SHOULD REMAIN WELL ABOVE NORMAL WITH HIGHS AROUND 90 AND LOWS NEAR 70. MODEL SOLUTIONS DIVERGE SIGNIFICANTLY LATE WEEK WITH ECMWF/GEM SUGGESTING NEXT STRONG SHRTWV TO MOVE INTO MEAN WRN TROF WILL CUT-OFF OVER THE ROCKIES AND THEN MOVE SLOWLY EAST... WHILE GFS SUGGESTS A MORE PROGRESSIVE SCENARIO. IN EITHER CASE... LOW POPS STILL WARRANTED FOR WED-THU... WHILE GFS INDICATES COOLER/DRIER CONDITIONS WILL OVERSPREAD THE AREA BY FRIDAY. THIS SOLUTION IN BETTER AGREEMENT WITH GOING FCST AND GIVEN EXCESSIVE UNCERTAINTY WITH LARGE MODEL DIFFERENCES... STAYED CLOSE TO PREVIOUS FCST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 648 AM EDT SAT AUG 23 2014 FOG CAUSING WIDESPREAD LIFR CONDITIONS ACROSS NRN INDIANA EARLY THIS MORNING. DIURNAL HEATING SHOULD ALLOW CONDITIONS TO GRDLY IMPROVE TO VFR BY THIS AFTN. STNRY FRONT REMAINS DRAPED ACROSS THE AREA AND MAY PROVIDE A FOCUS FOR TSRA THIS AFTN... HWVR CHANCES TOO LOW TO MENTION IN THE TAFS. DRIER AIR EXPECTED TO MOVE INTO THE AREA FROM THE EAST TONIGHT... BUT STILL SHOULD BE SUFFICIENT RADIATIONAL COOLING FOR SOME MVFR VSBYS IN BR TOWARD DAYBREAK. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...FISHER SHORT TERM...FISHER LONG TERM...JT AVIATION...JT VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
426 AM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 401 AM EDT SAT AUG 23 2014 WARM AND HUMID CONDITIONS WILL PERSIST FOR ONE MORE DAY BEFORE A BRIEF BREAK IN THE STICKY CONDITIONS ARRIVES TONIGHT INTO SUNDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND EVENING WITH CHANCES DIMINISHING TONIGHT. DRY CONDITIONS ARE EXPECTED UNTIL TUESDAY WHEN A COLD FRONT BEGINS TO APPROACH THE AREA. HIGHS WILL BE IN THE 80S WITH LOWS IN THE 60S THE NEXT COUPLE OF DAYS. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 401 AM EDT SAT AUG 23 2014 SEVERAL SMALLER ITEMS TO TRY TO SORT OUT FOR THE FORECAST. FIRST OFF WILL BE COMBINATION OF MOIST LOW LEVEL AIR MASS AND MOSTLY CLEAR SKIES ALLOWING FOR STRATUS/FOG DEVELOPMENT ACROSS THE AREA. OBSERVATIONS HAVE BEEN SHOWING THIS ALREADY TAKING PLACE...WITH ISSUES EXPECTED TO PERSIST THROUGH AT LEAST 10 AM BEFORE SUFFICIENT MIXING OCCURS TO HELP BREAK THINGS UP. NEXT UP WILL BE ATTEMPT TO ADVECT IN SOMEWHAT DRIER AIR FROM THE NE AGAINST THE PERSISTENT BUT WEAK SW FLOW ACROSS MUCH OF THE WESTERN GREAT LAKES. A SUBTLE BOUNDARY WAS LOCATED FROM S LK MICHIGAN TO VICINITY OF FT WAYNE. THIS FEATURE...COMBINED WITH WHAT APPEARS TO BE A MID LEVEL DISTURBANCE OR SERIES OF GRAVITY WAVES...HELPED SPARK SMALL AREAS OF SLOW MOVING SHOWERS AND STORMS THAT HAVE SINCE DISSIPATED. LOCATIONS ALONG AND SW OF THIS BOUNDARY WILL SEE A CHANCE FOR HIT OR MISS SHOWERS/STORMS THIS AFTERNOON/EVE IF SUFFICIENT HEATING CAN TAKE PLACE. WARM AND HUMID CONDITIONS WILL REMAIN UNTIL THE NE FLOW CAN STRENGTHEN SLIGHTLY AS RIDGE INFLUENCE BRIEFLY RELAXES WITH DEWPOINTS DROPPING INTO THE MID 60S (LOW 60S NE). A FEW RUNS OF THE RUC TRY TO BRING THIS DRIER AIR A BIT FASTER IN NE SECTIONS THAT CURRENTLY DEPICTED. GIVEN WEAK NATURE OF SLOW...THINK SLOWER IS BETTER AT THIS POINT UNTIL DEGREE OF MIXING CAN BE DETERMINED. AS A RESULT...HIGHS SHOULD REACH THE MID 80S WITH HEAT INDICES NEAR OR JUST INTO THE 90S. NE FLOW WILL PUSH AXIS OF BEST PRECIPITATION POTENTIAL TO THE SW OF THE REGION DURING THE EVENING HOURS...LEADING TO WHAT SHOULD BE A PLEASANTLY DRY NIGHT AS LOWS DROP INTO THE MID 60S TO NEAR 70. HAVE KEPT A LINGERING SLGT CHC OF SHOWERS IN FAR SW AREAS EARLY EVENING BUT THEN REMOVED ALL MENTION OF PRECIPITATION AFTER 3Z. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 401 AM EDT SAT AUG 23 2014 STRONG SHRTWV MOVG THROUGH NRN NEVADA THIS MORNING EXPECTED TO LIFT SLOWLY NE THROUGH THE NRN HIGH PLAINS SUNDAY WITH DOWNSTREAM RIDGE MOVG EAST ACROSS OUR CWA. LACK OF FORCING AND A LITTLE DRIER AIR ADVECTING INTO OUR AREA IN THE H925-H85 LAYER DUE TO EASTERLY FLOW AROUND STRENGTHENING ANTICYCLONE OVER THE LWR GRTLKS SUGGESTS DRY CONDITIONS ACROSS OUR AREA. GOOD DEAL OF SUNSHINE SHOULD ALLOW MIXING UP TO NEAR H850 WHICH WOULD RESULT IN HIGHS IN THE M-U80S. NRN PLAINS SHRTWV EXPECTED TO MOVE EAST TO ONTARIO ON MONDAY. RIDGE OVER THE UPR GRTLKS WILL FLATTEN OUT IN RESPONSE BUT SHOULD HOLD STRONG IN OUR AREA KEEPING CONDITIONS DRY. TEMPS EXPECTED TO CONTINUE SLOW WARMING TREND AS WINDS VEER MORE SOUTHERLY WITH HIGHS IN THE U80S/L90S. ONTARIO SHRTWV EXPECTED TO SHEAR OUT AND LIFT ENE INTO QUEBEC TUE WITH TRAILING CDFNT SINKING SLOWLY SOUTH INTO OR CLOSE TO NRN PORTION OF OUR CWA BY WED MORNING. TSTMS SHOULD DEVELOP ALONG THE FRONT AND MAY PROPAGATE SE INTO UNSTABLE AIRMASS OVER OUR AREA... BUT CAPPING INVERSION MAKES THIS SCENARIO DOUBTFUL... SO JUST CONTD WITH LOW CHC POPS. TEMPS SHOULD REMAIN WELL ABOVE NORMAL WITH HIGHS AROUND 90 AND LOWS NEAR 70. MODEL SOLUTIONS DIVERGE SIGNIFICANTLY LATE WEEK WITH ECMWF/GEM SUGGESTING NEXT STRONG SHRTWV TO MOVE INTO MEAN WRN TROF WILL CUT-OFF OVER THE ROCKIES AND THEN MOVE SLOWLY EAST... WHILE GFS SUGGESTS A MORE PROGRESSIVE SCENARIO. IN EITHER CASE... LOW POPS STILL WARRANTED FOR WED-THU... WHILE GFS INDICATES COOLER/DRIER CONDITIONS WILL OVERSPREAD THE AREA BY FRIDAY. THIS SOLUTION IN BETTER AGREEMENT WITH GOING FCST AND GIVEN EXCESSIVE UNCERTAINTY WITH LARGE MODEL DIFFERENCES... STAYED CLOSE TO PREVIOUS FCST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1209 AM EDT SAT AUG 23 2014 STRATUS AND FOG WILL POSE A CONCERN INTO SATURDAY MORNING AT BOTH SITES AS MOIST BOUNDARY LAYER REMAINS IN PLACE FROM RECENT RAINFALL AND ABUNDANT MOISTURE IN THE AREA. A BOUNDARY WAS LOCATED IN THE VICINITY OF BOTH SITES BUT WAS MOST ACTIVE IN AND AROUND KFWA WHERE A SMALL AREA OF SHOWERS/STORMS WAS PERSISTING. THIS SHOULD DRIFT SOUTHEAST OVER THE NEXT HALF HOUR TO HOUR WITH ADDITIONAL ACTIVITY UPSTREAM THAT COULD DRIFT SE TOWARDS THE AIRPORT AGAIN. WILL MONITOR FOR AMENDMENTS. OTHERWISE NO SIGNIFICANT CHANGES PLANNED TO TAFS INTO SATURDAY NIGHT AS OVERALL PATTERN WILL CHANGE LITTLE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...FISHER SHORT TERM...FISHER LONG TERM...JT AVIATION...FISHER VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS DES MOINES IA
416 AM CDT SAT AUG 23 2014 .SHORT TERM /TODAY/... ISSUED AT 415 AM CDT SAT AUG 23 2014 YET ANOTHER ACTIVE OVERNIGHT/EARLY MORNING TODAY WITH A LARGE AREA OF THUNDERSTORMS MOVING ACROSS WEST/SOUTHWEST IOWA AT THE CURRENT HOUR. THIS ACTIVITY IS ASSOCIATED WITH THE NOSE OF THE NOCTURNAL LOW LEVEL JET AND A SURGE OF WARM AIR ADVECTION ALOFT COMING OUT OF THE SOUTHERN PLAINS. EXPECT THE STORMS TO MOVE SLOWLY ACROSS MUCH OF THE FORECAST AREA THIS MORNING AND HAVE INCLUDED HIGH POPS ACCORDINGLY. WHILE LOCALLY HEAVY RAINFALL WILL OCCUR...THE BAR FOR FLASH FLOODING IS SET HIGH DUE TO ANTECEDENT AND VEGETATIVE CONDITIONS. AS THE WARM AIR ADVECTION SURGE CONTINUES NORTHWARD AND THE JET WEAKENS AFTER SUNRISE...EXPECT THE SWATH OF THUNDERSTORMS TO SHIFT TOWARD THE NORTH AND NORTHEAST AND GRADUALLY DIMINISH...LIKELY ENDING IN OUR NORTHEASTERN COUNTIES IN THE EARLY AFTERNOON. MEANWHILE...BEHIND THIS PUSH HOTTER CONDITIONS WILL MOVE INTO PARTICULARLY SOUTH/SOUTHWEST IOWA IN THE AFTERNOON. HEATING WILL BE MITIGATED BY MORNING CONVECTIVE DEBRIS CLOUDS...SOUTHEASTERLY LOW LEVEL WIND TRAJECTORIES...AND PERSISTENTLY HIGH DEWPOINTS...BUT BELIEVE TEMPERATURES SHOULD STILL EXCEED YESTERDAYS LEVELS IN THESE AREAS WITH LOWER 90S TYPICAL. HEAT INDEX VALUES WILL LIKELY TOP OUT IN THE 100 TO 105 DEGREE RANGE ONCE AGAIN...JUST BELOW ADVISORY CRITERIA AND PRECLUDING A HEADLINE ISSUANCE AT THIS TIME. .LONG TERM /TONIGHT THROUGH FRIDAY/... ISSUED AT 415 AM CDT SAT AUG 23 2014 UPPER LOW MOVING ACROSS IDAHO THIS MORNING...WILL CONTINUE TO SHIFT EAST/NORTHEAST INTO WESTERN NORTH DAKOTA BY MID DAY SUNDAY. STRONG PV ANOMALY OVER COLORADO AND NEW MEXICO WILL LIFT QUICKLY NORTH AND BE INGESTED IN THE UPPER LOW OVERNIGHT. THIS WILL HELP PUSH THE FRONTAL BOUNDARY WILL NORTH OF THE STATE AND PLACING THE AREA INTO THE WARM SECTOR. MUCH DRIER MID LEVELS WILL HELP LOWER PWATS DOWN TO NEAR 1.25 INCHES...WHICH WILL HELP STABILIZE THE ATMOSPHERE. THE SUB TROPICAL HIGH WILL REMAIN ENTRENCHED OVER THE SOUTHEAST CONUS AND WILL KEEP SOUTHWEST FLOW OVER THE STATE THROUGH THE EARLY PORTION OF THE WEEK. TEMPERATURES SHOULD BE QUITE WARM ON SUNDAY WITH THE THERMAL RIDGE IN PLACE WITH HIGHS IN THE UPPER 80S TO MID 90S. ANOTHER STRONG UPPER LOW WILL MOVE THROUGH THE INTERMOUNTAIN WEST MID NEXT WEEK AND WILL HELP THE FRONTAL BOUNDARY DROP INTO IOWA AND BECOME NEARLY STATIONARY ONCE AGAIN. THIS WILL RESULT INTO SEVERAL CHANCES FOR THUNDERSTORMS TUESDAY AND WEDNESDAY WITH SOME SEVERE WEATHER AND THE POTENTIAL FOR LOCALLY HEAVY RAINFALL. THE UPPER LEVEL SYSTEM WILL EVENTUALLY PUSH THE SFC BOUNDARY TO THE EAST OF THE STATE THOUGH THIS MAY NOT OCCUR UNTIL THURSDAY. A NEARLY 20 DEGREE DIFFERENCE IN TEMPERATURES NORTH AND SOUTH OF THE BOUNDARY WHILE IT IS STALLED OVER THE AREA WITH 70S NORTH TO NEAR 90 SOUTH. COOLER FOR THE ENTIRE AREA BY FRIDAY. && .AVIATION...23/06Z ISSUED AT 1150 PM CDT FRI AUG 22 2014 DELAYED CONVECTION UNTIL PAST 12Z SATURDAY FOR ALL TAF SITES AS THE 23/00Z HOPWRF AND HRRR ARE IN GOOD AGREEMENT WITH CONVECTION SPREADING ACROSS SOUTH-CENTRAL IOWA WITH THE HRRR MORE WIDESPREAD FURTHER NORTH. HAVE MENTION OF VCTS AT FOD/DSM/OTM WITH A LITTLE HIGHER CONFIDENCE SITES WILL SEE STORMS. HAVE MVFR TO IFR VIS WRT TO FOG PAST 08Z TONIGHT. MIXING DEVELOPS LATE SATURDAY MORNING AND KEPT MENTION OF GUSTS THROUGH THE AFTERNOON HOURS. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...LEE LONG TERM...DONAVON AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1150 PM CDT FRI AUG 22 2014 ...UPDATED AVIATION DISCUSSION... .SHORT TERM /TONIGHT/... ISSUED AT 327 PM CDT FRI AUG 22 2014 THROUGH EARLY EVENING...STORMS HAVE FIRED IN TWO AREAS ACROSS CENTRAL IOWA. THE NORTHERN MOST LINE OF STORMS IS ASSOCIATED WITH A FRONTAL BOUNDARY THAT IS EVER SO SLOWLY MEANDERING SOUTH. FLOW IS WEAK AND THERE IS LITTLE CONVERGENCE AND NO SHEAR TO SPEAK OF SO THE STORMS WILL BECOME OUTFLOW DOMINANT AND SHOULD FALL APART BY 00-01Z. FURTHER SOUTH STORMS HAVE FIRED ALONG A MOISTURE AXIS. THIS AXIS WAS EVIDENT ON RADAR FOR MUCH OF THE DAY AND STORMS FIRED AFTER SUFFICIENT HEATING DESTABILIZED THE ATMOSPHERE. THESE STORMS WILL BE A BIT MORE ROBUST AND PRODUCE LOCALLY HEAVY RAINFALL...SOME STRONGER WIND GUSTS AND POSSIBLY SOME SMALL HAIL. AGAIN...THESE STORMS SHOULD MOVE EAST SOUTHEAST AND DIMINISH SHORTLY AFTER 00Z. THE REST OF EARLY TO MID EVENING SHOULD BE RELATIVELY QUIET THOUGH THINGS WILL FESTER THROUGH THE EVENING SO ISOLATED STORMS WILL STILL BE POSSIBLE. FOR THE REST OF TONIGHT...UPPER RIDGE OVER IOWA WILL GET PUSHED TO THE EAST WITH THE AXIS BY 12Z SAT INTO WESTERN IL BY A DEEPENING TROUGH OVER THE ROCKIES. SEVERAL WEAKER SHORTWAVES WILL EJECT OUT OF THE BASE OF THE TROUGH PUSHING ACROSS NORTHERN/WESTERN IOWA. IN ADDITION...THE FRONTAL BOUNDARY FROM A SURFACE LOW IN WESTERN KS WILL LIFT NORTHWARD AS THE SURFACE LOW SHIFT TO THE NORTHEAST. TO THE WEST OF IOWA THERE IS PRETTY IMPRESSIVE SHEAR AND STRONG THETA-E ADVECTION THAT WILL WORK INTO THE WEST AND NORTH AND GRADUALLY SHIFT MORE NORTH AND EAST. ONE AGAIN THE 4KM WRF HAD A DECENT HANDLE ON ALL OF THE CONVECTION OF THIS AFTERNOON AND TONIGHT SO I DID PUT SOME WEIGHT ON ITS SOLUTION FOR TONIGHT. STORMS SHOULD FIRE OUT WEST OF IOWA THIS AFTERNOON AND EVENING AND WILL PROBABLY MERGE INTO A CLUSTER OF STORMS THAT WILL THEN SHIFT INTO THE SOUTHWEST THIRD OF SO OF IOWA DURING THE OVERNIGHT. THERE MAY BE ISOLATED STORMS THROUGHOUT THE EVENING BUT THE MAIN PRECIP EVENT WILL OCCUR OVER THE SOUTHWEST BETWEEN 08Z-12Z BEFORE LIFTING NORTH. SOME STORMS WILL PRODUCE HEAVY RAINFALL BUT THERE MAY ALSO BE A COUPLE SEVERE STORMS AS WELL...MAINLY OVER THE FAR WESTERN PORTION OF THE CWA. IT WILL BE A MUGGY NIGHT WITH LOWS IN THE UPPER 60S OVER FAR NORTHERN IOWA AND 70S ELSEWHERE. DEWPOINTS WILL STAY IN THE UPPER 60S AND LOW TO MID 70S SO FOG WILL ONCE AGAIN DEVELOP...ESPECIALLY ACROSS THE NORTH. .LONG TERM /SATURDAY THROUGH FRIDAY/... ISSUED AT 327 PM CDT FRI AUG 22 2014 ACTIVE WX PATTERN EXPECTED AT LEAST THROUGH THE MIDDLE OF NEXT WEEK...WITH HOT AND HUMID SUMMERTIME WEATHER GIVING WAY TO FALL-LIKE WEATHER. MID/UPPER-LEVEL WIND SPEED MAX PLUNGING SOUTHWARD ALONG THE PAC COAST...ON THE WEST SIDE OF THE WESTERN U.S. TROF...WILL HELP FACILIATE ITS INTENSIFICATION BEFORE IT LIFTS OUT. IN RESPONSE...THE EASTERN U.S. RIDGE WILL AMPLIFY INTO THIS WEEKEND. A VORT MAX OVER THE SW U.S. WILL CONTINUE LIFTING NORTHEASTWARD. BY THE BEGINNING OF THE LONG TERM FCST PERIOD...LINGERING CONVECTION FROM OVERNIGHT WILL CONTINUE LIFTING NORTHWARD AHEAD OF A NORTHWARD-ADVANCING FRONTAL BOUNDARY. THE BOUNDARY IS EXPECTED TO BE IN THE VICINITY OF THE IA- MN BORDER...LIKELY JUST NORTH OF IT...BY LATE AFTERNOON SATURDAY. SOUTH OF THE BOUNDARY...TEMPERATURES WILL WARM MORE THAN WHAT WAS SEEN TODAY. PREVIOUS FCST DISCUSSION ACKNOWLEDGED MIXING ISSUES OVER THE PAST FEW DAYS AND ON SATURDAY...AND AGREE WITH THAT THINKING HOWEVER EXPECT IT TO BE MORE THAN WAS SEEN TODAY AS EVIDENCED BY STRONGER SURFACE WINDS THAN WAS SEEN TODAY. THUS HAVE NUDGED TEMPS UP A DEGREE OR TWO FROM THE GOING FORECAST FOR SATURDAY AFTERNOON. ADDITIONAL CONVECTION IS POSSIBLE SATURDAY NIGHT AS ANOTHER MID/UPPER-LEVEL DISTURBANCE MOVES THROUGH THE CENTRAL/NORTHERN PLAINS. BEST FORCING WILL REMAIN WEST AND NORTH OF THE CWA...AND HAVE PAINTED POPS AS SUCH. SUNDAY IS EXPECTED TO BE THE WARMEST DAY OF THE FCST PD WITH IA SOLIDLY WITHIN THE WARM SECTOR. NAM HAS CONTINUED TREND FROM PREVIOUS FCST OF BEING THE WARMEST WITH FCST HIGHS WELL INTO THE 90S. NAM IS SUGGESTING MORE MIXING ON SUNDAY THAN ON SATURDAY AS EVIDENCED BY LOWER DEWPOINTS AND STRONGER SURFACE WINDS. FOR NOW HAVE NOT CHANGED SUNDAY/S MAX TEMPS MUCH FROM PREVIOUS FCST. HEAT INDEX VALUES WILL BE AS HIGH AS AROUND 100F. HIGHER CHANCES OF SHRA/TSRA OCCUR SUNDAY NIGHT AS UPPER-LEVEL TROF TO OUR WEST EJECTS NORTHEASTWARD AND PUSHES A BOUNDARY INTO IA. MODELS SUGGEST THE BOUNDARY WILL HANG UP IN THE STATE...LIKELY MAKING IT AS FAR SOUTHEAST AS CENTRAL IA. INSTABILITY AND FORCING WILL BE PLENTIFUL ENOUGH TO RESULT IN AT LEAST SCATTERED SHRA/TSRA DURING THE NIGHT. AS THE UPPER LEVEL TROF EJECTS...ADDITIONAL UPSTREAM ENERGY WILL HELP ANOTHER TROF TO DEVELOP IN ITS PLACE OVER THE NORTHERN U.S. ROCKIES. WITH BOUNDARY REMAINING IN THE REGION...HAVE KEPT SLIGHT CHANCE POPS GOING INTO MONDAY. AFTER THIS POINT...THE MODEL SOLUTIONS DIVERGE LEADING TO INCREASING FORECAST UNCERTAINTY. GFS BRINGS THE SECOND TROF THROUGH FASTER THAN THE EURO. EXPECT THE BOUNDARY TO MOVE THROUGH THE CWA BY WEDNESDAY. HAVE INCREASED POPS BEGINNING TUESDAY AND KEPT THEM IN PLACE THROUGH LATE IN THE DAY ON WEDNESDAY. AFTER THE FRONTAL PASSAGE...A FEW DAYS OF FALL-LIKE WEATHER WILL PREVAIL WITH HIGH TEMPS ACROSS THE NORTHERN CWA POSSIBLY NOT LEAVING THE LOWER 70S ON WEDNESDAY. && .AVIATION...23/06Z ISSUED AT 1150 PM CDT FRI AUG 22 2014 DELAYED CONVECTION UNTIL PAST 12Z SATURDAY FOR ALL TAF SITES AS THE 23/00Z HOPWRF AND HRRR ARE IN GOOD AGREEMENT WITH CONVECTION SPREADING ACROSS SOUTH-CENTRAL IOWA WITH THE HRRR MORE WIDESPREAD FURTHER NORTH. HAVE MENTION OF VCTS AT FOD/DSM/OTM WITH A LITTLE HIGHER CONFIDENCE SITES WILL SEE STORMS. HAVE MVFR TO IFR VIS WRT TO FOG PAST 08Z TONIGHT. MIXING DEVELOPS LATE SATURDAY MORNING AND KEPT MENTION OF GUSTS THROUGH THE AFTERNOON HOURS. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...FAB LONG TERM...ZOGG AVIATION...PODRAZIK
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
355 PM EDT SAT AUG 23 2014 .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 350 PM EDT SAT AUG 23 2014 19Z SFC ANALYSIS SHOWS OUR CONTINUING WEATHER CHALLENGE WITH THE LOW PRESSURE OUT TO THE WEST AND HIGH PRESSURE TO THE SOUTH. A WAVY NORTHWEST TO SOUTHEAST FRONT EXISTS JUST NORTH OF OUR AREA. MEANWHILE...ALOFT...A RIDGE IS FOUND THROUGH THE LOWER MIDSECTION OF THE NATION WITH A DIGGING TROUGH MOVING INTO THE MID ATLANTIC STATES. THIS PLACES CENTRAL AND EASTERN KENTUCKY IN THE TRACK OF ENERGY MOVING FROM THE UPPER MIDWEST INTO THE SOUTHERN APPALACHIANS TODAY. THESE FEATURES HAVE BEEN COMBINING LATELY TO PRODUCE CLUSTERS OF SHOWERS AND THUNDERSTORMS GENERALLY STARTING IN THE LATE AFTERNOON AND LASTING INTO THE EVENING. THE HIGH PW AIR IN PLACE OVER THE AREA...ALONG WITH THE DEWPOINTS PUSHING THE MID 70S...MAKES FOR PROLIFIC RAIN PRODUCING CELLS. AS HAS BEEN THE CASE REMAINS SO HEADING INTO LATE AFTERNOON...THOUGH THE AXIS OF CONCERN HAS SHIFTED SLIGHTLY WEST OWING TO THE WIGGLE OF THE RIDGE IN RESPONSE TO THE DIGGING TROUGH. CURRENTLY SCATTERED AND ISOLATED SHOWERS/STORMS ARE DOTTING THE CUMBERLAND VALLEY WITH SIGNS OF LARGER CLUSTERS STARTING TO TAKE SHAPE TO THE NORTHWEST. THOUGH DELAYED A BIT BY THE LOW STRATUS DECK FOLLOWING THE DENSE FOG THIS MORNING...TEMPERATURES HAVE CLIMBED SMARTLY INTO THE MIDDLE AND UPPER 80S THROUGH THE AREA AND WITH SUCH HIGH DEWPOINTS ARE YIELDING HEAT INDICES IN THE 95 TO 100 DEGREE RANGE. WINDS HAVE BEEN MAINLY LIGHT AND VARIABLE THROUGH THE AREA. THE MODELS ARE ALL IN PRETTY GOOD AGREEMENT ALOFT WITH THE WIGGLE WEST AND THEN BACK EAST OF THE UPPER RIDGE INTO MONDAY MORNING. SHORTWAVE ENERGY MOVING SOUTH BETWEEN THE UPPER SYSTEMS WILL PASS THROUGH CENTRAL AND EASTERN KENTUCKY TONIGHT WITH ONLY WEAKER PACKETS FORESEEN THROUGH THE REST OF THE WEEKEND. GIVEN THE AGREEMENT OF THE MODELS AND THE SMALLER SCALE NATURE OF CONVECTIVE ACTIVITY OF THIS REGIME HAVE AGAIN FAVORED THE HRRR AND NAM12 THROUGH THE FIRST 18 TO 36 HOURS AND A MODEL CONSENSUS AFTER THAT INTO MONDAY MORNING. SENSIBLE WEATHER WILL FEATURE ISOLATED AND SCATTERED CONVECTION AROUND EAST KENTUCKY THROUGH THE NEXT SEVERAL HOURS WITH AN DECENT POTENTIAL EVOLUTION OF STORMS INTO A LARGER SYSTEM LATER IN THE FIRST PART OF THE EVENING SOMEWHERE TO THE NORTHWEST. THE INGREDIENTS ARE THERE FOR ANOTHER ROUND OF SUCH STORMS AND THE EXCESSIVE RAINFALL THEY PRODUCE. STILL THE BEST INDICATIONS ARE THAT THE WORST OF ANY SUCH DEVELOPMENT WILL JUST BRUSH OUR SOUTHWESTERN COUNTIES WHERE WE ARE NOT QUITE AS SATURATED AS THE EAST. THIS IS GOOD NEWS...BUT GIVEN THE LOW FFG IN THE EAST JUST ABOUT ANY HEALTHY STORM THERE WILL PROMPT FLASH FLOODING CONCERNS. WITH THE STILL HIGH PWS AND INSTABILITY ACROSS THE ENTIRE AREA CANNOT CALL ANY PLACE FREE OF LOCALIZED FLASH FLOOD CONCERNS. THE ACTIVITY IS EXPECTED TO DIE DOWN LATER THIS EVENING AND WHEN COMBINED WITH AT LEAST PARTIAL CLEARING WILL LIKELY BRING ABOUT ANOTHER BLANKET OF FOG BECOMING DENSE IN AREAS TOWARD DAWN. WILL HIT THIS...IN ADDITION TO THE STORM/FLOOD CONCERNS...HARD IN THE HWO. ONCE THE FOG BURNS OFF ON SUNDAY...PARTLY SUNNY SKIES WILL AGAIN BUILD THE HEAT AND INSTABILITY THROUGH THE AREA WHILE LOWER PWS FOR MUCH OF THE AREA WILL LIMIT TO A SMALLER EXTENT FLASH FLOOD CONCERNS. EXPECT SOME COOLER AND...MORE IMPORTANTLY...DRIER AIR TO MAKE IT INTO THE EAST BY EVENING AS A BACK DOOR COLD FRONT PUSHES WEST THROUGH THE AREA ALLOWING SOME LOWS CLOSER TO NORMAL FOR THIS TIME OF YEAR IN THE FAR EAST BY DAWN MONDAY. AGAIN PATCHY FOG WILL BE A CONCERN DEPENDING ON THE RAINS OF THE PREVIOUS DAY AND CLEARING THAT NIGHT. STUCK WITH THE CONSSHORT AS A STARTING POINT FOR THE T/TD/WINDS THROUGH THE FIRST 24 HOURS AND THE SUPERBLEND THEREAFTER. MADE SOME MINOR ADJUSTMENTS BASED ON TERRAIN FOR LOWS TONIGHT AND SUNDAY NIGHT. AS FOR POPS...ENDED UP CLOSER TO THE WETTER MET GUIDANCE TONIGHT AND THEN NEARER THE MAV NUMBERS FOR THE REST OF THE SHORT TERM PORTION OF THE FORECAST. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 239 PM EDT SAT AUG 23 2014 STRONG RIDGING WILL DOMINATE THE EASTERN CONUS THROUGH NEXT WEEK WITH SUMMER-LIKE WEATHER CONTINUING. FORTUNATELY...WITH A STRONGER CAP PRESENT...CONVECTION WILL BE HELD MORE AT BAY. CANNOT RULE OUT A STRAY AFTERNOON SHOWER OR STORM EACH DAY...BUT SHOULD BE NOTHING LIKE WE HAVE SEEN LATELY. PLANNING TO GO WITH A DIURNAL TREND WITH POPS THROUGH THE END OF THE PERIOD WITH POPS PEAKING EACH AFTERNOON WITH MAXIMUM HEATING/INSTABILITY. A SURFACE TROUGH MAY APPROACH FROM THE WEST EARLY NEXT WEEKEND...BUT A TROPICAL SYSTEM DEVELOPING OVER THE ATLANTIC BASIN...MAY HAVE A TENDENCY TO SLOW DOWN THE ADVANCEMENT OF THIS FEATURE UNTIL SOMETIME LATE IN THE WEEKEND OR THE FOLLOWING WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 200 PM EDT SAT AUG 23 2014 SCATTERED SHOWERS AND THUNDERSTORMS WILL BE A CONCERN INTO THE EVENING FOR ALL SITES...THOUGH THE BEST CHANCES WILL BE HAD AT LOZ AND SME. WITH ANY STORMS...EXPECT LOWER CIGS...INTO THE MVFR RANGE...AND A POTENTIAL FOR IFR VIS. OTHERWISE...VFR WILL PREVAIL INTO THE EVENING. THE AMPLE BOUNDARY LAYER MOISTURE AND PARTIAL CLEARING EXPECTED TONIGHT SHOULD SET THE STAGE FOR ROBUST FOG DEVELOPMENT THROUGH THE ENTIRE AREA. ACCORDINGLY HAVE BROUGHT IN DENSE...VLIFR...FOG AT ALL SITES LATE TONIGHT. THE FOG BURNS OFF BY 14Z SUNDAY WITH VRF CONDITIONS ANTICIPATED AHEAD OF SCATTERED STORM DEVELOPMENT IN THE AFTERNOON FOR WESTERN PARTS OF THE AREA. WINDS THROUGH THE PERIOD WILL BE MAINLY LIGHT AND VARIABLE. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...KAS AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
242 PM EDT SAT AUG 23 2014 .SYNOPSIS... A FRONTAL BOUNDARY ACROSS THE MID ATLANTIC STATES WILL MOVE SOUTHWEST OF THE AREA TODAY. HIGH PRESSURE FROM NEW ENGLAND SLOWLY BUILDS INTO THE AREA TONIGHT INTO SUNDAY...BEFORE SETTLING OVER THE PIEDMONT EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE HRRR AND RUC ALL INDICATE THE SHOWERS OVER THE SW PART OF THE CWA WILL CONTINUE SE AND EXIT THE AREA BY EARLY AFTERNOON. OTHER SHOWERS OVER MD WILL MOVE INTO THE NORTHERN NECK AND THE DELMARVA DURING THE EARLY AFTERNOON. THESE WILL BE WEAKENING AS THEY ENCOUNTER DRIER AIR. HAVE RAISED POPS SOME ALONG THE LINES OF BOTH AREAS OF SHOWERS. ALSO HAVE LOWERED THE MAX TEMPERATURE A LITTLE AS NOT MUCH SUNSHINE TODAY AND WITH WINDS COMING OFF THE OCEAN WILL HELP TO KEEP TEMPERATURES LOWER. PREVIOUS DISCUSSION...LATEST SFC ANALYSIS REVEALS HI PRES CENTERED OVR NEW ENGLAND AND A DISORGANIZED PRES FIELD OVR THE MID ATLANTIC REGION COINCIDING WITH A WEAK STALLED FRNTAL BNDRY. ALOFT...NW FLOW CONTINUES WITH AN UPR-LEVEL RIDGE CENTERED OVR THE E-CNTRL CONUS. THE SFC FRNT WILL SAG S INTO THE CAROLINAS TDA. EXPECT ANOTHER DAY WITH SCT SHRAS/TSTMS...ESPECIALLY OVR THE PIEDMONT CLOSER TO THE FRNT. THE POTENTIAL FOR THUNDER WILL BE CONFINED AWAY FROM THE CSTS DUE TO NE FLOW WITH HI PRES BLDG OVR NEW ENGLAND. NOT EXPECTING ANY SVR WX BUT HEAVY RAIN IS PSBL IN SOME AREAS. AFTN HI TEMPS WILL RANGE FM THE UPR 70S TO NEAR 80 OVR THE LWR ERN SHORE TO THE LO-MID 80S ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... THE HIGH SURGES SSW OVER THE AREA TONIGHT INTO SUNDAY WITH THE SURFACE RIDGE AXIS SETTLING OVER THE PIEDMONT BY MONDAY. THIS WILL PRODUCE A DRYING TREND ALONG WITH A NE WIND THAT SHOULD BE RATHER BREEZY ALONG THE COAST. PARTLY TO MOSTLY SUNNY CONDITIONS ARE EXPECTED BY SUNDAY...WITH MOSTLY CLEAR/SUNNY CONDITIONS BY SUNDAY NIGHT AND MONDAY. HIGHS WILL BE BELOW SEASONAL AVERAGES THROUGH MONDAY (AROUND -1 ST DEV). HIGHS SUNDAY AND MONDAY WILL RANGE FROM THE UPPER 70S TO LOW 80S. LOWS SHOULD BE IN THE MID/UPPER 60S SUNDAY MORNING...WITH MAINLY LOW/MID 60S EXPECTED MONDAY MORNING. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... SFC HIGH PRESSURE AND UPPER LEVEL RIDGING ALONG THE EASTERN SEABOARD IS EXPECTED TO CONTINUE THROUGH MID NEXT WEEK. THIS PATTERN WILL MAINTAIN A COOLER AIRMASS OVER THE AREA THROUGH WED BEFORE THE RIDGE AXES AT THE SFC AND ALOFT ALOFT BEGIN TO SHIFT JUST EAST OF THE FA...AND MOVING OFFSHORE BY THU. THE FORECAST IS GENERALLY DRY THROUGH THE EXTENDED FORECAST PERIODS DUE TO WELL-ESTABLISHED SUBSIDENCE THROUGH THE ATMOSPHERIC PROFILE...HOWEVER A FEW SHOWERS CANNOT BE RULED OUT NEAR THE FAR SE VA/NE NC COAST ON WED DUE TO THE POTENTIAL FOR WRAPAROUND MOISTURE FROM THE TROPICAL SYSTEM PASSING WELL TO THE EAST. HIGH AND LOW TEMPERATURES WILL RUN BELOW NORMAL FROM MON NIGHT THROUGH WED NIGHT (LOWS IN THE 60S...UPPER 50S FAR WRN COUNTIES/HIGHS IN THE LOW-MID 80S...MID-UPPER 70S BEACHES) AND THEN REBOUND TWD SEASONAL NORMALS THU/THU NIGHT (HIGHS IN THE MID-UPPER 80S...UPPER 70S-LOWER 80S BEACHES/LOWS IN THE MID-UPPER 60S...AROUND 70 BEACHES). && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... MVFR SHOWERS AND CEILINGS WILL PERSIST OVERNIGHT DUE TO THE SATURATED AIRMASS ACROSS THE AREA. HIGH PRESSURE TO THE NORTH WILL CONTINUE TO BUILD SOUTH PUSHING DRIER AIR INTO THE MID-ATLANTIC. THIS WILL HELP CLEAR THE SHOWERS AND CEILINGS BY SUNDAY MORNING. EXPECT VFR CONDITIONS TO PREVAIL SUN AFTN WITH A CONTINUED NE WIND. OUTLOOK...DRY WEATHER IS FORECAST FOR SEVERAL DAYS BEGINNING SUNDAY AS MID AND LOWER RIDGING TAKES PLACE OVER THE AREA. && .MARINE... FRONTAL BOUNDARY NOW SOUTH OF THE AREA WITH HIGH PRESSURE BUILDING SOUTH FROM NEW ENGLAND. DESPITE THE ONGOING E-NE WINDS...LATEST GUIDANCE NOT AS BULLISH WITH THE WINDS THUS CREATING SOME DOUBT WHEN SCA CONDITIONS WILL START. TOUGHEST CALL WILL BE SOUTHERN CHES BAY WHERE ONLY MINIMAL CONDITIONS WILL BE MEET. MOUTH OF THE BAY WILL HAVE AN EARLIER START AND LATER FINISH TIME. SEAS (ESPECIALLY OUT NEAR 20 NM) ARE EXPECTED TO BUILD TO 5 FEET THEN REMAIN THERE THROUGH EARLY NEXT WEEK...SO EXTENDED THE SCA HEADLINES OVR THE WATERS THRU SUNDAY NIGHT. FOR CONTINUITY SAKE...WENT AHEAD AND HOISTED SCA HEADLINES FOR CURRITUCK SND SUN AND SUN NIGHT AS SCNDRY SURGE WILL LIKELY KEEP WINDS BTWN 15-20 KTS. FORECAST NEXT WEEK WILL DEPEND ON THE TRACK OF A DEVELOPING (TROPICAL) LOW PROGGED TO TRACK NE BUT REMAIN EAST OF GULF STREAM WALL. SWELL FROM THIS SYSTEM WILL EVENTUALLY AFFECT THE MID ATLNTC BEACH AREAS. && .TIDES/COASTAL FLOODING... TIDES PROGGED TO BUILD TO ABOUT 1 FOOT ABOVE NORMAL EARLY NEXT WEEK AS THE NE FLOW CONTINUES. DESPITE THE PERSISTENT ONSHORE FLOW...LEVELS EXPECTED TO REMAIN ABOUT 1/2 FOOT BELOW MINOR FLOODING THRESHOLDS. WENT WITH A MODERATE RIP CURRENT THREAT TODAY GIVEN NEARSHORE WAVES OF 2-3 FT AND A INCREASING NE WIND FLOW. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR MDZ025. NC...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR NCZ102. VA...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR VAZ098>100. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 2 AM EDT MONDAY FOR ANZ634. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 PM EDT SUNDAY FOR ANZ632. SMALL CRAFT ADVISORY FROM 8 AM SUNDAY TO 6 AM EDT MONDAY FOR ANZ633. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT MONDAY FOR ANZ654. SMALL CRAFT ADVISORY FROM 2 AM SUNDAY TO 6 AM EDT MONDAY FOR ANZ656-658. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT MONDAY FOR ANZ650-652. && $$ SYNOPSIS...AJZ/MAS NEAR TERM...MAS/JAB SHORT TERM...AJZ/MAS LONG TERM...BMD AVIATION...DAP MARINE...MPR TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1054 AM EDT SAT AUG 23 2014 .SYNOPSIS... A FRONTAL BOUNDARY ACROSS THE MID ATLANTIC STATES WILL MOVE SOUTHWEST OF THE AREA TODAY. HIGH PRESSURE FROM NEW ENGLAND SLOWLY BUILDS INTO THE AREA TONIGHT INTO SUNDAY...BEFORE SETTLING OVER THE PIEDMONT EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE HRRR AND RUC ALL INDICATE THE SHOWERS OVER THE SW PART OF THE CWA WILL CONTINUE SE AND EXIT THE AREA BY EARLY AFTERNOON. OTHER SHOWERS OVER MD WILL MOVE INTO THE NORTHERN NECK AND THE DELMARVA DURING THE EARLY AFTERNOON. THESE WILL BE WEAKENING AS THEY ENCOUNTER DRIER AIR. HAVE RAISED POPS SOME ALONG THE LINES OF BOTH AREAS OF SHOWERS. ALSO HAVE LOWERED THE MAX TEMPERATURE A LITTLE AS NOT MUCH SUNSHINE TODAY AND WITH WINDS COMING OFF THE OCEAN WILL HELP TO KEEP TEMPERATURES LOWER. PREVIOUS DISCUSSION...LATEST SFC ANALYSIS REVEALS HI PRES CENTERED OVR NEW ENGLAND AND A DISORGANIZED PRES FIELD OVR THE MID ATLANTIC REGION COINCIDING WITH A WEAK STALLED FRNTAL BNDRY. ALOFT...NW FLOW CONTINUES WITH AN UPR-LEVEL RIDGE CENTERED OVR THE E-CNTRL CONUS. THE SFC FRNT WILL SAG S INTO THE CAROLINAS TDA. EXPECT ANOTHER DAY WITH SCT SHRAS/TSTMS...ESPECIALLY OVR THE PIEDMONT CLOSER TO THE FRNT. THE POTENTIAL FOR THUNDER WILL BE CONFINED AWAY FROM THE CSTS DUE TO NE FLOW WITH HI PRES BLDG OVR NEW ENGLAND. NOT EXPECTING ANY SVR WX BUT HEAVY RAIN IS PSBL IN SOME AREAS. AFTN HI TEMPS WILL RANGE FM THE UPR 70S TO NEAR 80 OVR THE LWR ERN SHORE TO THE LO-MID 80S ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... THE HIGH SURGES SSW OVER THE AREA TONIGHT INTO SUNDAY WITH THE SURFACE RIDGE AXIS SETTLING OVER THE PIEDMONT BY MONDAY. THIS WILL PRODUCE A DRYING TREND ALONG WITH A NE WIND THAT SHOULD BE RATHER BREEZY ALONG THE COAST. PARTLY TO MOSTLY SUNNY CONDITIONS ARE EXPECTED BY SUNDAY...WITH MOSTLY CLEAR/SUNNY CONDITIONS BY SUNDAY NIGHT AND MONDAY. HIGHS WILL BE BELOW SEASONAL AVERAGES THROUGH MONDAY (AROUND -1 ST DEV). HIGHS SUNDAY AND MONDAY WILL RANGE FROM THE UPPER 70S TO LOW 80S. LOWS SHOULD BE IN THE MID/UPPER 60S SUNDAY MORNING...WITH MAINLY LOW/MID 60S EXPECTED MONDAY MORNING. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... SFC HIGH PRESSURE AND UPPER LEVEL RIDGING ALONG THE EASTERN SEABOARD IS EXPECTED TO CONTINUE THROUGH MID NEXT WEEK. THIS PATTERN WILL MAINTAIN A COOLER AIRMASS OVER THE AREA THROUGH WED BEFORE THE RIDGE AXES AT THE SFC AND ALOFT ALOFT BEGIN TO SHIFT JUST EAST OF THE FA...AND MOVING OFFSHORE BY THU. THE FORECAST IS GENERALLY DRY THROUGH THE EXTENDED FORECAST PERIODS DUE TO WELL-ESTABLISHED SUBSIDENCE THROUGH THE ATMOSPHERIC PROFILE...HOWEVER A FEW SHOWERS CANNOT BE RULED OUT NEAR THE FAR SE VA/NE NC COAST ON WED DUE TO THE POTENTIAL FOR WRAPAROUND MOISTURE FROM THE TROPICAL SYSTEM PASSING WELL TO THE EAST. HIGH AND LOW TEMPERATURES WILL RUN BELOW NORMAL FROM MON NIGHT THROUGH WED NIGHT (LOWS IN THE 60S...UPPER 50S FAR WRN COUNTIES/HIGHS IN THE LOW-MID 80S...MID-UPPER 70S BEACHES) AND THEN REBOUND TWD SEASONAL NORMALS THU/THU NIGHT (HIGHS IN THE MID-UPPER 80S...UPPER 70S-LOWER 80S BEACHES/LOWS IN THE MID-UPPER 60S...AROUND 70 BEACHES). && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... KEPT A TEMPO GROUP FOR -RA NEXT FEW HOURS AT KRIC AS THE BATCH OF RAIN CROSSES THE PIEDMONT. OTW...HIGH PRS TO THE NE ALLOWING FOR DRYER AIR ALONG THE COAST WITH MAINLY VFR CNDTNS THIS AM. EXPECT VFR CIGS TODAY WITH TSCTNS SHOWING PLNTY OF MOISTURE ARND THE AREA FOR A BKN SC DECK (3-4K FT) THRU MUCH OF THE FCST PRD WITH MVFR CIGS RETURNING AFTER 00Z. SCT CONVECTION PSBL AFTER 18Z...BUT TIMING OF ANY SHWR/TSTRM PROBLEMATIC AT THIS POINT SO KEPT PCPN OUT OF FCST AFTER 18Z. OUTLOOK...MVFR/IFR CONDITIONS PSBL DUE TO STRATUS/FOG SUN MORNING. OTW...DRY WEATHER IS FORECAST FOR SEVERAL DAYS BEGINNING SUNDAY. && .MARINE... FRONTAL BOUNDARY NOW SOUTH OF THE AREA WITH HIGH PRESSURE BUILDING SOUTH FROM NEW ENGLAND. DESPITE THE ONGOING E-NE WINDS...LATEST GUIDANCE NOT AS BULLISH WITH THE WINDS THUS CREATING SOME DOUBT WHEN SCA CONDITIONS WILL START. TOUGHEST CALL WILL BE SOUTHERN CHES BAY WHERE ONLY MINIMAL CONDITIONS WILL BE MEET. MOUTH OF THE BAY WILL HAVE AN EARLIER START AND LATER FINISH TIME. SEAS (ESPECIALLY OUT NEAR 20 NM) ARE EXPECTED TO BUILD TO 5 FEET THEN REMAIN THERE THROUGH EARLY NEXT WEEK...SO EXTENDED THE SCA HEADLINES OVR THE WATERS THRU SUNDAY NIGHT. FOR CONTINUITY SAKE...WENT AHEAD AND HOISTED SCA HEADLINES FOR CURRITUCK SND SUN AND SUN NIGHT AS SCNDRY SURGE WILL LIKELY KEEP WINDS BTWN 15-20 KTS. FORECAST NEXT WEEK WILL DEPEND ON THE TRACK OF A DEVELOPING (TROPICAL) LOW PROGGED TO TRACK NE BUT REMAIN EAST OF GULF STREAM WALL. SWELL FROM THIS SYSTEM WILL EVENTUALLY AFFECT THE MID ATLNTC BEACH AREAS. && .TIDES/COASTAL FLOODING... TIDES PROGGED TO BUILD TO ABOUT 1 FOOT ABOVE NORMAL EARLY NEXT WEEK AS THE NE FLOW CONTINUES. DESPITE THE PERSISTANT ONSHORE FLOW...LEVELS EXPECTED TO REMAIN ABOUT 1/2 FOOT BELOW MINOR FLOODING THRESHOLDS. WENT WITH A MODERATE RIP CURRENT THREAT TODAY GIVEN NEARSHORE WAVES OF 2-3 FT AND A INCREASING NE WIND FLOW. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR MDZ025. NC...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR NCZ102. VA...MODERATE RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR VAZ098>100. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 2 AM EDT MONDAY FOR ANZ634. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 PM EDT SUNDAY FOR ANZ632. SMALL CRAFT ADVISORY FROM 8 AM SUNDAY TO 6 AM EDT MONDAY FOR ANZ633. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT MONDAY FOR ANZ654. SMALL CRAFT ADVISORY FROM 2 AM SUNDAY TO 6 AM EDT MONDAY FOR ANZ656-658. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT MONDAY FOR ANZ650-652. && $$ SYNOPSIS...AJZ/MAS NEAR TERM...MAS/JAB SHORT TERM...AJZ/MAS LONG TERM...BMD AVIATION...MPR MARINE...MPR TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1119 PM EDT SUN AUG 24 2014 LATEST UPDATE... AVIATION .SYNOPSIS... ISSUED AT 328 PM EDT SUN AUG 24 2014 MONDAY AND TUESDAY WILL SEE WARMER AND MORE HUMID CONDITIONS WITH SCATTERED THUNDERSTORMS. SOME HEAVIER RAIN IS POSSIBLE TUESDAY NIGHT AS A COLD FRONT SINKS SOUTH THROUGH LOWER MICHIGAN. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT) ISSUED AT 328 PM EDT SUN AUG 24 2014 FORECAST IMPACTS IN THE NEAR TERM INCLUDE PATCHY FOG TONIGHT ALONG WITH HEAT INDICES IN THE LOWER 90S MONDAY AND TUESDAY AFTERNOON. SCATTERED THUNDERSTORMS ARE POSSIBLE AS LIFTED INDICES ARE AROUND MINUS 6 BOTH DAYS...BUT COVERAGE WILL BE ISOLATED TO SCATTERED BEFORE THE COLD FRONT ARRIVES LATER TUESDAY TO FOCUS CONVECTION. SEVERE WEATHER RISK IS LIMITED AS SHEAR REMAINS RELATIVELY WEAK. FLOODING POTENTIAL IS THERE HOWEVER. SEE HYDROLOGY SECTION FOR DETAILS. LOOKS LIKE THE MOST FAVORABLE CONDITIONS FOR HEAVY RAIN OCCUR TUESDAY NIGHT. .LONG TERM...(WEDNESDAY THROUGH SUNDAY) ISSUED AT 328 PM EDT SUN AUG 24 2014 A COLD FRONT SHOULD BE NEAR THE MI/IN BORDER WEDNESDAY AS HIGH PRESSURE BUILDS IN FROM WISCONSIN. WE PUSHED POPS A BIT FARTHER SOUTH WEDNESDAY BUT THE EXACT POSITION OF THE FRONTAL BOUNDARY ISN/T CERTAIN AT THIS POINT. IT/S LIKELY THOUGH THE THE BULK OF THE PCPN ASSOCIATED WITH THE BOUNDARY WILL BE OVER NORTHERN INDIANA OR PERHAPS FAR SOUTHERN LOWER MICHIGAN. THE BOUNDARY BEGINS LIFTING NORTHWARD THURSDAY IN RESPONSE TO DEVELOPING LOW PRESSURE IN THE PLAINS. WE/LL KEEP A SLIGHT CHANCE OF PCPN IN THE GRIDS BUT MOST LOCATIONS WILL BE DRY. THE BEST CHANCE OF RAIN LOOKS TO BE FRIDAY/SATURDAY WHEN THE LOW MOVES ENE TOWARD LOWER MICHIGAN AND THE WARM FRONT MOVES NORTH ACROSS THE CWA. HIGHS WILL BE IN THE MID TO UPPER 70S THROUGH THE PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1120 PM EDT SUN AUG 24 2014 IT WOULD SEEM FOG IS BECOMING LESS LIKELY OVERNIGHT. AS I WROTE FOR THE 00Z TAF SET...THE WINDS IN THE BOUNDARY LAYER OF BETWEEN 15 AND 25 KNOTS ARE ENOUGH TO KEEP SURFACE FOG FROM BECOMING MUCH OF AN ISSUE TONIGHT. INSTEAD THE IR-FOG LOOP SHOWS PATCHY LOW CLOUDS (MVFR CIGS) DEVELOPING NEAR AND SOUTH OF I-96. AS THE AIR CONTINUES TO COOL OVERNIGHT THE LOW CLOUDS SHOULD BECOME MORE EXTENSIVE AND CIGS SHOULD LOWER SOME. SO I HAVE ONLY MVFR CIGS/VSBY AT ALL TAF SITES. THE CONVECTION FOR MONDAY STILL SEEMS POSSIBLE. THE LATEST VERSION OF THE RAP MODEL AND THE NAM12 SHOW LATE MORNING AND AFTERNOON CONVECTION. SO...I NOW HAVE VCTS AFTER 15Z FOR THAT. I WOULD EXPECT ONCE THE SUN SETS MONDAY EVENING THE CONVECTION WILL BE DONE. THERE SHOULD BE ENOUGH WIND TOMORROW NIGHT TO KEEP FOG FROM BECOMING AN ISSUE. && .MARINE... ISSUED AT 328 PM EDT SUN AUG 24 2014 WINDS WILL VEER TO THE SOUTH ON MONDAY BUT WAVES WILL ONLY BUILD TO AROUND 2 FEET AS FLOW WILL BE RELATIVELY LIGHT. VISIBILITY COULD BE REDUCED AT TIMES IN FOG TONIGHT THROUGH TUESDAY. THUNDERSTORMS ARE POSSIBLE MONDAY AND TUESDAY AFTERNOONS. && .HYDROLOGY... ISSUED AT 1104 AM EDT SUN AUG 24 2014 BEST CHANCE FOR SIGNIFICANT RAINFALL WOULD BE MONDAY NIGHT THROUGH WEDNESDAY WITH A SLOW MOVING COLD FRONT. THIS IS NOT A GUARANTEE AS THE LLJ IS FORECAST TO BE QUITE WEAK. NEVERTHELESS...A VERY MOIST ATMOSPHERE COMBINED WITH FORCING VIA THE COLD FRONT AND SLOW CELL MOVEMENT COULD RESULT IN SOME SIGNIFICANT RAINFALL IF STORMS DEVELOP OVER OUR AREA. PW VALUES WILL LIKELY BE AROUND 1.75" MONDAY NIGHT AND TUESDAY. MODEL GUIDANCE IS MIXED REGARDING HOW LONG THE FRONT MAY HANG UP...SO IT IS UNCLEAR WHEN THE THREAT FOR SIGNIFICANT RAINFALL WOULD END. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS...OSTUNO SHORT TERM...OSTUNO LONG TERM...93 AVIATION...WDM HYDROLOGY...HOVING MARINE...OSTUNO
AREA FORECAST DISCUSSION
NWS GAYLORD MI
405 PM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 405 PM EDT SAT AUG 23 2014 HIGH PRESSURE TO OUR EAST WILL PROVIDE FOR LIGHT SOUTHERLY BREEZES...AND INCREASING WARMTH AND HUMIDITY THROUGH MONDAY. FOR THE MOST PART THE WEEKEND LOOKS DRY...BUT SHOWERS AND THUNDERSTORM CHANCES WILL INCREASE ON MONDAY...AHEAD OF A WEAK COLD FRONT THAT WILL ENTER NORTHERN MICHIGAN MONDAY NIGHT. && .SHORT TERM...(THIS EVENING THROUGH TONIGHT) ISSUED AT 405 PM EDT SAT AUG 23 2014 SHARP MID LEVEL RIDGE AXIS CONTINUES TO POKE UP INTO THE WESTERN GREAT LAKES ROUGHLY FROM EASTERN WISCONSIN UP THROUGH CENTRAL UPPER MICHIGAN...DOWNSTREAM OF STRONG SHORT WAVE TROUGHING ACROSS THE NRN ROCKIES INTO THE NRN PLAINS. BROAD LOW PRESSURE ACROSS THE CENTRAL PLAINS WITH A SFC WARM FRONT DRAPED ACROSS MISSOURI INTO THE OHIO RIVER VALLEY. ELEVATED WARM FRONT AND THETA-E PLUME HAS SPREAD NORTHWARD ACROSS THE MIDWEST INTO THE LOWER GREAT LAKES AND CONTINUES TO BE THE MAIN WEATHER FOCUS WITH YET ANOTHER ROUND OF CONVECTION WORKING ACROSS THE MIDWEST THIS AFTERNOON. ACROSS THE NRN GREAT LAKES...WEAK HIGH PRESSURE IS DRAPED ACROSS NRN MICHIGAN. BUT...SUBTLE LOW-MID LEVEL TROUGH AXIS ANALYZED ACROSS WESTERN/CENTRAL UPPER MICHIGAN ALONG NE FRINGE OF DEEPER MOISTURE GRADIENT...WHERE RUC ANALYSIS CONTINUES TO DEPICT A STRONG LOW-MID LEVEL DEFORMATION AXIS STRETCHING FROM NRN LAKE MICHIGAN UP THROUGH CENTRAL UPPER MICHIGAN. THIS HAS/IS GENERATING A BAND OF SHOWERS UP THROUGH THAT AREA PARTICULARLY AROUND THE ESCANABA AREA (TERRAIN INFLUENCED) TRYING TO BLEED ACROSS NRN LAKE MICHIGAN ALTHOUGH PRECIP APPEARS TO FINALLY BE WINDING DOWN. SOME HEATING INDUCED CONVECTION ALSO ONGOING IN NE WISCONSIN WITHIN THE BETTER MOISTURE FIELD. ACROSS NRN LOWER MICHIGAN...STUBBORN LAKE STRATUS IN EASTERN UPPER AND NE LOWER MICHIGAN HAS MOSTLY MIXED OUT INTO A FLAT CU FIELD. NO SIGNS OF ANY PRECIP. BUT SOLID LAKE STRATUS REMAINS LOCKED ACROSS WESTERN LAKE HURON INTO THE STRAITS...SIGNS OF THINGS TO COME I THINK. TONIGHT...NO PRECIP AS MAIN FOCUS WILL REMAIN WEST-THROUGH-SOUTH OF NRN MICHIGAN. WILL ENJOY A FEW HOURS OF CLR TO PARTLY CLOUDY SKIES THIS EVENING AS HEATING INDUCE CU/STCU DECK FADES AWAY. BUT WITH PERSISTENT EASTERLY FLOW JUST OFF THE DECK...VEERING SOUTHEAST OVERNIGHT...SUSPECT MARINE LAYER/LAKE STRATUS AND FOG OUT ACROSS LAKE HURON WILL ONCE AGAIN GET SCOOPED INTO EASTERN UPPER MICHIGAN AND NORTHEAST LOWER MICHIGAN DURING THE OVERNIGHT HOURS. HAVE TAILORED THE FORECAST THAT WAY ALONG WITH PATCHY TO AREAS OF FOG OVERNIGHT. A REPEAT ON TEMPS WITH A BIT OF A MUGGY NIGHT (RELATIVELY SPEAKING) AND LOWS IN THE UPPER 50S TO MIDDLE 60S. && .LONG TERM...(SUNDAY THROUGH SATURDAY) ISSUED AT 405 PM EDT SAT AUG 23 2014 ...WARM START...COOLER FINISH TO THE UPCOMING WEEK... HIGH IMPACT WEATHER POTENTIAL: MINIMAL. SOME THUNDER POTENTIAL AT TIMES THIS WEEK. PATTERN SYNOPSIS/ANTICIPATED EVOLUTION: AMPLIFIED PATTERN SOO TALKED ABOUT THE LAST SEVERAL DAYS LOOKS TO REACH MATURATION SUNDAY...WHEN MOST IMPRESSIVE RIDGE AXIS/HEAT DOME OF THIS SUMMER BUILDS DIRECTLY OVERHEAD AND UP INTO SOUTHEAST CANADA. WESTERN TROUGHING CONTINUES...WITH LEAD EJECTING RATHER ROBUST SHORTWAVE LOOKING TO PUT A KIBOSH ON FURTHER RIDGE AMPLIFICATION HEADING INTO THE START OF NEXT WORK WEEK. PATTERN THERE-ON-AFTER LOOKS TO BECOME AN INCREASINGLY FLATTER ONE AS STRONGEST CORES OF UPPER LEVEL JET ENERGY SLICE WEST/EAST ACROSS SOUTHERN CANADA. A CHANGEABLE PATTERN FOR SURE...AND ONE THAT SIMPLE FORCES ANOTHER EXTENDED STRETCH OF LOW CONFIDENCE SHOWER AND STORM FORECAST EVOLUTION. PRIMARY FORECAST CONCERNS/CHALLENGES: JUST HOW WARM TO GO SUNDAY/MONDAY AND ADDRESSING WHAT INITIALLY LOOKS TO BE MULTI-PERIOD SHOWER AND THUNDERSTORM CHANCES RIGHT THROUGH THE WEEK. DETAILS: TAKE TODAY`S WEATHER...TACK ON A FEW DEGREES...SUNDAYS WEATHER DONE! MORE SIGNIFICANT CHANGES TAKE PLACE MONDAY AS RIDGE APEX PUSHES EAST AND EARLIER MENTIONED SHORTWAVE PUNCHES UP INTO SOUTH CENTRAL CANADA. SOUTHWEST FLOW RAMPS UP IN RESPONSE...DRIVING A GOOD CHUNK OF CURRENT SOUTHERN PLAINS HEAT DOME ALONG WITH IT. H8 TEMPS MAKE A RUN INTO THE UPPER TEENS...READINGS NOT YET SEEN AROUND THESE PARTS THIS SUMMER. INCREASING PRESSURE GRADIENT ON FRONT SIDE OF APPROACHING/ALBEIT STEADILY DECAYING/COLD FRONT SHOULD ONLY HELP THE SURFACE WARMING CAUSE. TEMPERATURES WELL INTO THE 80S A SURE BET FOR AREAS SOUTH OF THE BIG BRIDGE...AND NOT OUT OF THE REALM OF POSSIBILITY A FEW FAVORED DOWNSLOPE AREAS OF NORTHEAST LOWER MAKE A RUN A 90. NOW...THAT SAME FRONT MAY BRING A SHOWER AND STORM THREAT ALONG WITH IT. DEFINITELY NOT ENTIRELY SOLD ON THIS IDEA GIVEN FAR REMOVED MID LEVEL SUPPORT AND QUICKLY DECAYING FORCED SURFACE CONVERGENCE. ATMOSPHERE ALSO HAS THE LOOK OF BEING RATHER CAPED...WITH NOTED H8 WARM NOSE. WHILE OVERALL AIRMASS BECOMES INCREASINGLY MOIST...SET-UP SCREAMS OF DECENT LOW LEVEL MIXING OUT OF MOISTURE...AND STARTING TO WONDER IF PROGGED UPPER 60 DEWPOINTS ARE SEVERAL DEGREES TOO HIGH. NO DOUBT ABOVE LEAVES PLENTY OF OPPORTUNITY FOR A DRY LATE MONDAY FRONTAL PASSAGE. INHERITED LOW CHANCES WILL DO FOR NOW...BUT TRULY BELIEVE MANY WILL SEE LITTLE...IF ANY...RAIN. SAID FRONT LOOKS TO SIGNIFICANTLY SLOW ITS SOUTH PROGRESS MONDAY NIGHT THROUGH TUESDAY NIGHT AS IT BECOMES INCREASINGLY ALIGNED WITH DEEP LAYER WESTERLY FLOW. JUST WHERE IT STALLS OUT IS OPEN TO PLENTY OF DEBATE...BUT GIVEN BREADTH OF PREFRONTAL WARMING AND TOTAL DETACHMENT OF ANY MID LEVEL SUPPORT...KINDA FEEL IT MAY STRUGGLE TO CLEAR OUR SOUTHERN COUNTIES UNTIL SOMETIME TUESDAY NIGHT. NOW...THAT LEADS TO A TRICKY TEMPERATURE AND SHOWER FORECAST RIGHT THROUGH MID WEEK. AS FOR TEMPERATURES...TUESDAY HAS THE POTENTIAL TO BE DOWNRIGHT WARM...ESPECIALLY FOR AREAS NEAR SAGINAW BAY...WHERE TEMPERATURES MAY ONCE AGAIN REACH INTO THE MID AND UPPER 80S. COOLER AIR ARRIVES WEDNESDAY...WITH HIGHS MOSTLY IN THE 70S (ALL DEPENDENT ON THAT WHOLE FRONTAL TIMING THING OF COURSE). NEARLY ALL GUIDANCE REMAINS STEADFAST ON ADDITIONAL SHOWER/STORM DEVELOPMENT ALONG AND NORTH OF THE SURFACE FRONT AS WEAK MID LEVEL IMPULSES RIDE ALONG IT MONDAY NIGHT RIGHT INTO WEDNESDAY. ANY DECENT SUPPORT IS FAR FROM CERTAIN...AND JUST NOT BUYING THIS WET LOOK IN GUIDANCE. MUCH LIKE MONDAY...LOWER POPS THE WAY TO GO FOR NOW...WITH PLENTY OF TIME TO WORK ON BETTER TEMPORAL AND SPATIAL RESOLUTION OF SHOWER/STORM CHANCES IN THE COMING DAYS. SOME HINTS WHAT IS LEFT OF WESTERN TROUGHING GETS SHUNTED EAST LATE IN THE WEEK...FORCING FRONT BACK NORTH AND DRUMMING UP ADDITIONAL RAIN CHANCES TO START NEXT WEEKEND. TIMING WILL CHANGE...AND A SIMPLE CONSENSUS BLEND APPROACH WILL BE UTILIZED FOR NOW....WHICH INDEED HOLDS OFF NEXT MENTION FOR SHOWERS/STORMS UNTIL FRIDAY NIGHT AND SATURDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 132 PM EDT SAT AUG 23 2014 STUBBORN STRATUS DECK FLOWING OFF LAKE HURON ON EASTERLY WINDS CONTINUES TO BRING MVFR FLIGHT CONDITIONS TO PLN/APN...ALTHOUGH STRATUS DECK HAS/IS SLOWLY ERODING. CLOUDS SHOULD SCATTER OUT BY MID TO LATE AFTERNOON AT THOSE SITES LEAVING A PERIOD OF VFR CONDITIONS HEADING INTO THE EVENING. VFR CONDITIONS AT TVC AND MBL WILL PERSIST. TONIGHT...FEAR CYCLE WILL REPEAT AS MARINE STRATUS ONCE AGAIN REDEVELOPS OFF THE LAKE INTO NE LOWER MICHIGAN...LATER THIS EVENING AND FOR THE OVERNIGHT HOURS WITHIN PERSISTENT E/SE FLOW. THUS...HAVE IFR CIGS AND LOW VSBYS ONCE AGAIN TAKING OFF AT APN/PLN THROUGH THE COURSE OF THE NIGHT WHILE TVC/MBL REMAIN LARGELY VFR WITH SOME MINOR REDUCTIONS TO VSBY DUE TO LIGHT FOG. WINDS...LIGHT EASTERLY TODAY...CALM TONIGHT AND LIGHT SE ON SUNDAY. && .MARINE... ISSUED AT 405 PM EDT SAT AUG 23 2014 ABUNDANT MARINE STRATUS AND FOG WILL CONTINUE TO IMPACT THE NEARSHORE AREAS OF NRN LAKE HURON INTO THE SAINT MARYS RIVER SYSTEM...TONIGHT INTO SUNDAY BEFORE STRONGER SOUTHERLY WINDS DEVELOP LATER SUNDAY INTO MONDAY AND FINALLY SCOURS OUT THE STRATUS/FOG. OTHERWISE...LIGHT EASTERLY WINDS TONIGHT WILL VEER MORE SOUTHEASTERLY THEN SOUTH ON SUNDAY...INCREASING SUNDAY NIGHT INTO MONDAY. MAY DEVELOP ENOUGH GUSTINESS TO WARRANT SMALL CRAFT ADVISORIES FOR PARTS OF NRN LAKE MICHIGAN BY MONDAY MORNING...ALTHOUGH LAKE STABILITY MAY KEEP WINDS/WAVES IN CHECK. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ SYNOPSIS...AM SHORT TERM...ADAM LONG TERM...MSB AVIATION...ADAM MARINE...ADAM
AREA FORECAST DISCUSSION
NWS GAYLORD MI
133 PM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 246 AM EDT SAT AUG 23 2014 HIGH PRESSURE TO OUR EAST WILL PROVIDE FOR LIGHT SOUTHERLY BREEZES...AND INCREASING WARMTH AND HUMIDITY THROUGH MONDAY. FOR THE MOST PART THE WEEKEND LOOKS DRY...BUT SHOWERS AND THUNDERSTORM CHANCES WILL INCREASE ON MONDAY...AHEAD OF A WEAK COLD FRONT THAT WILL ENTER NORTHERN MICHIGAN MONDAY NIGHT. && .UPDATE... ISSUED AT 1111 AM EDT SAT AUG 23 2014 SHARP MID LEVEL RIDGE AXIS CONTINUES TO POKE UP INTO THE WESTERN GREAT LAKES...DOWNSTREAM OF STRONG SHORT WAVE TROUGHING ACROSS THE NRN ROCKIES INTO THE NRN PLAINS. BROAD LOW PRESSURE ACROSS THE CENTRAL PLAINS WITH A SFC WARM FRONT DRAPED ACROSS THE MIDWEST INTO THE OHIO VALLEY...AND CONTINUES TO BE THE MAIN WEATHER FOCUS WITH YET ANOTHER ROUND OF CONVECTION IN THE MIDWEST. ACROSS NRN MICHIGAN...A BUNCH OF LITTLE THINGS HAPPENING. WEAK HIGH PRESSURE IS DRAPED ACROSS NRN MICHIGAN. BUT...SUBTLE LOW-MID LEVEL TROUGH AXIS ANALYZED ACROSS WESTERN/CENTRAL UPPER MICHIGAN ALONG NE FRINGE OF DEEPER MOISTURE GRADIENT...WHERE RUC ANALYSIS REVEALS A STRONG LOW-MID LEVEL DEFORMATION AXIS STRETCHING FROM NRN LAKE MICHIGAN UP THROUGH CENTRAL UPPER MICHIGAN. THIS IN TURN HAS/IS GENERATING A BAND OF SHOWERS UP THROUGH THAT AREA. ONE POCKET OF RAIN IN PARTICULAR HAS SEEMINGLY LATCHED ON TO THE TERRAIN INCREASE OFF LAKE MICHIGAN AND HAS BROUGHT SOME LOCALLY HEAVY RAIN THROUGH THAT AREA. NOTHING LIKE THAT HAPPENING HERE. BUT...BATCH OF VERY STUBBORN STRATUS CONTINUES TO FLOW OFF LAKE HURON WITHIN EASTERLY FLOW...BRINGING CLOUDY SKIES TO PARTS OF EASTERN UPPER AND NE LOWER MICHIGAN. STRATUS IS BEGINNING TO ERODE...BUT PROCESS IS TAKING IT/S TIME. REST OF TODAY...STRATUS IN THE EAST AND IN EASTERN UPPER MICHIGAN WILL EVENTUALLY ERODE/MIX OUT...BUT IT WILL TAKE SEVERAL MORE HOURS AS EAST FLOW CONTINUES TO PUMP COOL/MOIST MARINE AIR INTO THOSE AREAS. HAVE STRETCHED CLOUDY SKIES OUT FOR SEVERAL MORE HOURS. ELSEWHERE...HEATING INDUCED CLOUD COVER SHOULD DEVELOP OVER NW LOWER MICHIGAN AND WE MAY SEE SOME OF THAT AFOREMENTIONED DEFORMATION CLOUD COVER EXPAND DOWN INTO NW LOWER MICHIGAN AS WELL. SO... EITHER CLOUDY BECOMING PARTLY SUNNY...OR SUNNY BECOMING PARTLY SUNNY WILL BE THE NAME OF THE GAME THIS AFTERNOON. TEMPS WILL OF COURSE BE TRICKY GIVEN THE CLOUDS...AND AREAS EAST OF I-75 WILL END UP WITH THE LOWER READINGS AND HAVE TWEAKED MAX TEMPS ACCORDINGLY. BUT...IT WILL NOT TAKE MUCH FOR TEMPS TO REBOUND WHEN THE SUN FINALLY DOES BREAK OUT. JUST HOPE WE DON/T GET SOME SORT OF DIFFERENTIAL HEATING BOUNDARY ACROSS NRN LOWER/EASTERN UPPER MICHIGAN THAT POPS OFF CONVECTION THIS AFTERNOON. THINK WE ARE TOO CAPPED FOR THAT...BUT WILL SEE. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 246 AM EDT SAT AUG 23 2014 HIGH IMPACT WEATHER POTENTIAL: MINIMAL PRIMARY FORECAST CHALLENGES: DO SHOWERS MOVE INTO NORTHERN MICHIGAN? CURRENTLY, AS WAS MENTIONED AT THE EARLIER UPDATE, RAIN SHOWERS UPSTREAM OF THE FORECAST AREA ARE JUST SOUTH OF MQT AND SAW AND ALONG THE 700 MB DEWPOINT DEPRESSION GRADIENT, AND IN THE LFQ OF THE 500 MB 30 KNOT JET STREAK MOVING THROUGH N WISCONSIN. MAIN FORCING THAT IS GOING ON OVERNIGHT IS OVER FARTHER SOUTH AND WEST IN NEBRASKA WHERE THE DEEPER SFC LOW AND 500 MB VORT AND SPEED MAXES ARE DIGGING. THIS HAS GIVEN RISE TO THE COMPLEX OF STORMS IN THE CENTRAL PLAINS. THE SFC LOW IN THE E COLORADO IS LINKED BY A SLOWLY STRENGTHENING FRONT THAT STRETCHES TO THE NE THROUGH N MINNESOTA AND UP INTO JAMES BAY TO A WEAKER SFC LOW. TODAY...THE MODELS ARE IN GOOD AGREEMENT WITH THE RUC/NAM12/GFS/ECMWF/LOCAL WRF4KM SHOWING THE MORNING ISOLATED SHOWERS THAT WILL TRY TO PUSH INTO NW LOWER THIS MORNING. HOWEVER, AS THE 500 MB RIDGE OVER THE UPPER GREAT LAKES CONTINUES TO AMPLIFY, THE FORCING FOR THE SHOWERS WILL GET PUSHED TO THE NORTH AND WEST THROUGH THE AFTERNOON. THE FRONT WILL ALSO MOVE TO THE NORTH AND WEST AS THE SFC LOW IN E COLORADO MOVES OUT OVER THE CENTRAL PLAINS AND DEEPENS. THIS WILL HELP TO FOCUS MOST OF THE RAIN INSTABILITY AND THE DYNAMIC SUPPORT OVER THE NORTHERN PLAINS AS DEPICTED BY SPC. TONIGHT...THIS MOVEMENT OF THE SFC LOW OUT OF THE CENTRAL PLAINS WILL PUSH INTO NORTH DAKOTA OVERNIGHT CONTINUING TO PULL THE FOCUS AWAY FROM THE UPPER GREAT LAKES. THIS SHOULD CONTINUE OUR RAIN FREE STREAK (OR AT LEAST OUR MEASURABLE PRECIPITATION) THROUGH THE NIGHT. WHILE THERE IS SOME INSTABILITY, THE LACK OF A FOCUS AND THE CAPPING EXPECTED IN THE EVENING (BLAYER CIN 20-40 J/KG) SHOULD INHIBIT ANY SHOWERS FROM GETTING GOING. IT DOESN`T LOOK LIKE THERE IS MUCH IN THE WAY OF ELEVATED INSTABILITY AS THE SHOWALTER INDEX OVER N MICHIGAN AT ITS LOWEST IS ONLY +2C. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 246 AM EDT SAT AUG 23 2014 A HIGHLY AMPLIFIED 500MB RIDGE WILL BE OVERHEAD TO START OUR SUNDAY. AN EJECTING UPPER LOW FROM THE NORTHERN HIGH PLAINS WILL HAVE TO CREST THIS RIDGE...AND WILL PASS WELL TO OUR NORTH MONDAY NIGHT. THIS WILL FLATTEN OUT THE RIDGE...THOUGH IN OUR NECK OF THE WOODS 500MB HEIGHTS WILL HARDLY LOWER AT ALL. STILL...AN ASSOCIATED COLD FRONT WILL SLOWLY GET DRAGGED INTO THE AREA MONDAY NIGHT. UNTIL THAT HAPPENS...IT WILL BE SOMETHING OF A CHALLENGE TO GET A PRECIP THREAT GOING IN THESE PARTS. BUT IT WON/T BE CHALLENGING TO BECOME INCREASINGLY WARM AND HUMID. SUNDAY...CORE OF THE 500MB RIDGE STARTS TO SLIDE DOWNSTREAM IN THE AFTERNOON. THAT CORRESPONDS WITH A SLIGHT UPTICK IN 1000-850MB RETURN FLOW. HOWEVER...A SHORTWAVE RIDGE ASCENDING INTO THE LARGER RIDGE WILL HELP KEEP HEIGHTS HIGH. AT THE SAME TIME...SURFACE HIGH PRESSURE TO OUR EAST WILL STILL EXTEND A TOUCH OF RIDGING INTO NORTHERN MI. FROM A CONCEPTUAL MODEL STANDPOINT...IT WILL BE DIFFICULT TO FIRE OFF CONVECTION IN THIS PATTERN UNTIL HEIGHTS ALOFT FALL. INDEED...THE MODELS ARE NOT INCLINED TO PROG MUCH IF ANY CAPE. 00Z NAM HAS A LATE-DAY AXIS OF A FEW HUNDRED J/KG OF MUCAPE... HUGGING THE LAKE MI COAST FROM LTL TRAV BAY SOUTH. THIS IS WHERE LAKE BREEZE CONVERGENCE AND MOISTURE POOLING WILL BE CONCENTRATED... THANKS TO A BACKGROUND LIGHT SE SYNOPTIC SURFACE WIND. EVEN SO...AN 82/65 PARCEL HAS ABOUT 50J/KG OF CIN TO OVERCOME...THANKS TO 700MB TEMPS AROUND 9C. SO WILL MAINTAIN A DRY FORECAST. CAN GENERALLY EXPECT PARTLY SUNNY SKIES...WILL SOME BUBBLY CU AND MID/HIGH DEBRIS CLOUDS (INSTABILITY WILL BE MUCH HIGHER W OF LAKE MI). MAX TEMPS UPPER 70S (EASTERN UPPER...AND NE LOWER COAST)...TO LOW/MID 80S (INTERIOR SW SECTIONS). SUN NIGHT/MONDAY...SUB-850MB FLOW MAINTAIN AN EASTERLY COMPONENT INTO THE EVENING...BEFORE VEERING S TO EVEN SSW OVERNIGHT. THAT WILL ALLOW A JUICIER AND POTENTIALLY UNSTABLE AIRMASS TO FINALLY MAKE INROADS. HOWEVER...THAT WILL BE SLOW AT 1ST...WITH PERHAPS WESTERN CHIP/MACK THE ONLY PLACE PROGGED TO SEE SOME CAPE ARRIVE BY MORNING. THIS COULD ALLOW CONVECTION ORIGINATING IN WI A CHANCE TO GRAZE BY THAT AREA OVERNIGHT. BUT...GIVEN THE MODELS TEND TO BE TOO QUICK TO BREAK DOWN RIDGING AND CIN...WILL MAINTAIN A DRY FORECAST FOR SUN NIGHT. DEEP MOISTURE/MODERATE INSTABILITY PLUME WILL VERY SLOWLY WORK IN FROM THE WNW MONDAY...AHEAD OF A COLD FRONT ADVANCING ACROSS WI. HEIGHTS/TEMPS ALOFT HERE REMAIN HIGH...BUT ACTIVITY SHOULD DEVELOP UPSTREAM IN WI AND MOVE E AND NE TOWARD WESTERN/NORTHERN SECTIONS...ESPECIALLY LATER IN THE DAY. WILL MAINTAIN CHANCE POPS BY AFTERNOON IN THE NW 2/3DS OF THE FORECAST AREA...INCLUDING HIGH CHANCE (50) POPS IN WESTERN CHIP/MACK. MIN TEMPS NEAR 60F TO THE MID 60S. MAX TEMPS NEAR 80 TO THE MID 80S...A FEW UPPER 80S POSSIBLE IN THE INTERIOR OF NORTHERN LOWER. DEW POINTS WILL BE RISING INTO THE MID AND UPPER 60S...SO IT WILL ALSO BE QUITE STICKY ON MONDAY. REST OF THE FORECAST...SHAPING UP FOR A FAVORABLE MCS PATTERN MID-WEEK. A STALLED FRONTAL ZONE (AND A WARM/HUMID AIRMASS) WILL BE JUST TO OUR SOUTH...WITH FAST ZONAL FLOW IN THE NORTHERN LAKES. CONSALL GRIDS ARE TRYING TO NUDGE US TOWARD LIKELY POPS IN SOME PERIODS. AM BACKING AWAY FROM THIS THINKING GIVEN THAT IT/S CONVECTION WE/RE TALKING ABOUT...AND PRECIP HAS UNDERPERFORMED OVER THE LAST WEEK OR SO. TEMPS WILL BE DRIFTING BACK TOWARD OR A BIT UNDER CLIMO BY LATE IN THE WORK WEEK...THOUGH PROBABLY NOT AS COOL AS THE GFS/MEX GUIDANCE ADVERTISES...AS THE ECMWF IS SLOWER AND LESS AMPLIFIED WITH THE UPPER TROF THAT PROGRESSES INTO THE PLAINS STATES MID/LATE WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 132 PM EDT SAT AUG 23 2014 STUBBORN STRATUS DECK FLOWING OFF LAKE HURON ON EASTERLY WINDS CONTINUES TO BRING MVFR FLIGHT CONDITIONS TO PLN/APN...ALTHOUGH STRATUS DECK HAS/IS SLOWLY ERODING. CLOUDS SHOULD SCATTER OUT BY MID TO LATE AFTERNOON AT THOSE SITES LEAVING A PERIOD OF VFR CONDITIONS HEADING INTO THE EVENING. VFR CONDITIONS AT TVC AND MBL WILL PERSIST. TONIGHT...FEAR CYCLE WILL REPEAT AS MARINE STRATUS ONCE AGAIN REDEVELOPS OFF THE LAKE INTO NE LOWER MICHIGAN...LATER THIS EVENING AND FOR THE OVERNIGHT HOURS WITHIN PERSISTENT E/SE FLOW. THUS...HAVE IFR CIGS AND LOW VSBYS ONCE AGAIN TAKING OFF AT APN/PLN THROUGH THE COURSE OF THE NIGHT WHILE TVC/MBL REMAIN LARGELY VFR WITH SOME MINOR REDUCTIONS TO VSBY DUE TO LIGHT FOG. WINDS...LIGHT EASTERLY TODAY...CALM TONIGHT AND LIGHT SE ON SUNDAY. && .MARINE... ISSUED AT 246 AM EDT SAT AUG 23 2014 OVER THE NEXT 48 HOURS, THE WINDS WILL SLOWLY INCREASE AND VEER FROM THE EAST TO THE SOUTH LOW PRESSURE NEAR COLORADO DEEPENS AND MOVES INTO NORTH DAKOTA. SO TODAY THROUGH SUNDAY NIGHT, WILL EXPECT THAT WINDS AND WAVES WILL REMAIN BELOW SMALL CRAFT CONDITIONS. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...ADAM SYNOPSIS...JZ SHORT TERM...JL LONG TERM...JZ AVIATION...ADAM MARINE...JL
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1112 AM EDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 246 AM EDT SAT AUG 23 2014 HIGH PRESSURE TO OUR EAST WILL PROVIDE FOR LIGHT SOUTHERLY BREEZES...AND INCREASING WARMTH AND HUMIDITY THROUGH MONDAY. FOR THE MOST PART THE WEEKEND LOOKS DRY...BUT SHOWERS AND THUNDERSTORM CHANCES WILL INCREASE ON MONDAY...AHEAD OF A WEAK COLD FRONT THAT WILL ENTER NORTHERN MICHIGAN MONDAY NIGHT. && .UPDATE... ISSUED AT 1111 AM EDT SAT AUG 23 2014 SHARP MID LEVEL RIDGE AXIS CONTINUES TO POKE UP INTO THE WESTERN GREAT LAKES...DOWNSTREAM OF STRONG SHORT WAVE TROUGHING ACROSS THE NRN ROCKIES INTO THE NRN PLAINS. BROAD LOW PRESSURE ACROSS THE CENTRAL PLAINS WITH A SFC WARM FRONT DRAPED ACROSS THE MIDWEST INTO THE OHIO VALLEY...AND CONTINUES TO BE THE MAIN WEATHER FOCUS WITH YET ANOTHER ROUND OF CONVECTION IN THE MIDWEST. ACROSS NRN MICHIGAN...A BUNCH OF LITTLE THINGS HAPPENING. WEAK HIGH PRESSURE IS DRAPED ACROSS NRN MICHIGAN. BUT...SUBTLE LOW-MID LEVEL TROUGH AXIS ANALYZED ACROSS WESTERN/CENTRAL UPPER MICHIGAN ALONG NE FRINGE OF DEEPER MOISTURE GRADIENT...WHERE RUC ANALYSIS REVEALS A STRONG LOW-MID LEVEL DEFORMATION AXIS STRETCHING FROM NRN LAKE MICHIGAN UP THROUGH CENTRAL UPPER MICHIGAN. THIS IN TURN HAS/IS GENERATING A BAND OF SHOWERS UP THROUGH THAT AREA. ONE POCKET OF RAIN IN PARTICULAR HAS SEEMINGLY LATCHED ON TO THE TERRAIN INCREASE OFF LAKE MICHIGAN AND HAS BROUGHT SOME LOCALLY HEAVY RAIN THROUGH THAT AREA. NOTHING LIKE THAT HAPPENING HERE. BUT...BATCH OF VERY STUBBORN STRATUS CONTINUES TO FLOW OFF LAKE HURON WITHIN EASTERLY FLOW...BRINGING CLOUDY SKIES TO PARTS OF EASTERN UPPER AND NE LOWER MICHIGAN. STRATUS IS BEGINNING TO ERODE...BUT PROCESS IS TAKING IT/S TIME. REST OF TODAY...STRATUS IN THE EAST AND IN EASTERN UPPER MICHIGAN WILL EVENTUALLY ERODE/MIX OUT...BUT IT WILL TAKE SEVERAL MORE HOURS AS EAST FLOW CONTINUES TO PUMP COOL/MOIST MARINE AIR INTO THOSE AREAS. HAVE STRETCHED CLOUDY SKIES OUT FOR SEVERAL MORE HOURS. ELSEWHERE...HEATING INDUCED CLOUD COVER SHOULD DEVELOP OVER NW LOWER MICHIGAN AND WE MAY SEE SOME OF THAT AFOREMENTIONED DEFORMATION CLOUD COVER EXPAND DOWN INTO NW LOWER MICHIGAN AS WELL. SO... EITHER CLOUDY BECOMING PARTLY SUNNY...OR SUNNY BECOMING PARTLY SUNNY WILL BE THE NAME OF THE GAME THIS AFTERNOON. TEMPS WILL OF COURSE BE TRICKY GIVEN THE CLOUDS...AND AREAS EAST OF I-75 WILL END UP WITH THE LOWER READINGS AND HAVE TWEAKED MAX TEMPS ACCORDINGLY. BUT...IT WILL NOT TAKE MUCH FOR TEMPS TO REBOUND WHEN THE SUN FINALLY DOES BREAK OUT. JUST HOPE WE DON/T GET SOME SORT OF DIFFERENTIAL HEATING BOUNDARY ACROSS NRN LOWER/EASTERN UPPER MICHIGAN THAT POPS OFF CONVECTION THIS AFTERNOON. THINK WE ARE TOO CAPPED FOR THAT...BUT WILL SEE. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 246 AM EDT SAT AUG 23 2014 HIGH IMPACT WEATHER POTENTIAL: MINIMAL PRIMARY FORECAST CHALLENGES: DO SHOWERS MOVE INTO NORTHERN MICHIGAN? CURRENTLY, AS WAS MENTIONED AT THE EARLIER UPDATE, RAIN SHOWERS UPSTREAM OF THE FORECAST AREA ARE JUST SOUTH OF MQT AND SAW AND ALONG THE 700 MB DEWPOINT DEPRESSION GRADIENT, AND IN THE LFQ OF THE 500 MB 30 KNOT JET STREAK MOVING THROUGH N WISCONSIN. MAIN FORCING THAT IS GOING ON OVERNIGHT IS OVER FARTHER SOUTH AND WEST IN NEBRASKA WHERE THE DEEPER SFC LOW AND 500 MB VORT AND SPEED MAXES ARE DIGGING. THIS HAS GIVEN RISE TO THE COMPLEX OF STORMS IN THE CENTRAL PLAINS. THE SFC LOW IN THE E COLORADO IS LINKED BY A SLOWLY STRENGTHENING FRONT THAT STRETCHES TO THE NE THROUGH N MINNESOTA AND UP INTO JAMES BAY TO A WEAKER SFC LOW. TODAY...THE MODELS ARE IN GOOD AGREEMENT WITH THE RUC/NAM12/GFS/ECMWF/LOCAL WRF4KM SHOWING THE MORNING ISOLATED SHOWERS THAT WILL TRY TO PUSH INTO NW LOWER THIS MORNING. HOWEVER, AS THE 500 MB RIDGE OVER THE UPPER GREAT LAKES CONTINUES TO AMPLIFY, THE FORCING FOR THE SHOWERS WILL GET PUSHED TO THE NORTH AND WEST THROUGH THE AFTERNOON. THE FRONT WILL ALSO MOVE TO THE NORTH AND WEST AS THE SFC LOW IN E COLORADO MOVES OUT OVER THE CENTRAL PLAINS AND DEEPENS. THIS WILL HELP TO FOCUS MOST OF THE RAIN INSTABILITY AND THE DYNAMIC SUPPORT OVER THE NORTHERN PLAINS AS DEPICTED BY SPC. TONIGHT...THIS MOVEMENT OF THE SFC LOW OUT OF THE CENTRAL PLAINS WILL PUSH INTO NORTH DAKOTA OVERNIGHT CONTINUING TO PULL THE FOCUS AWAY FROM THE UPPER GREAT LAKES. THIS SHOULD CONTINUE OUR RAIN FREE STREAK (OR AT LEAST OUR MEASURABLE PRECIPITATION) THROUGH THE NIGHT. WHILE THERE IS SOME INSTABILITY, THE LACK OF A FOCUS AND THE CAPPING EXPECTED IN THE EVENING (BLAYER CIN 20-40 J/KG) SHOULD INHIBIT ANY SHOWERS FROM GETTING GOING. IT DOESN`T LOOK LIKE THERE IS MUCH IN THE WAY OF ELEVATED INSTABILITY AS THE SHOWALTER INDEX OVER N MICHIGAN AT ITS LOWEST IS ONLY +2C. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 246 AM EDT SAT AUG 23 2014 A HIGHLY AMPLIFIED 500MB RIDGE WILL BE OVERHEAD TO START OUR SUNDAY. AN EJECTING UPPER LOW FROM THE NORTHERN HIGH PLAINS WILL HAVE TO CREST THIS RIDGE...AND WILL PASS WELL TO OUR NORTH MONDAY NIGHT. THIS WILL FLATTEN OUT THE RIDGE...THOUGH IN OUR NECK OF THE WOODS 500MB HEIGHTS WILL HARDLY LOWER AT ALL. STILL...AN ASSOCIATED COLD FRONT WILL SLOWLY GET DRAGGED INTO THE AREA MONDAY NIGHT. UNTIL THAT HAPPENS...IT WILL BE SOMETHING OF A CHALLENGE TO GET A PRECIP THREAT GOING IN THESE PARTS. BUT IT WON/T BE CHALLENGING TO BECOME INCREASINGLY WARM AND HUMID. SUNDAY...CORE OF THE 500MB RIDGE STARTS TO SLIDE DOWNSTREAM IN THE AFTERNOON. THAT CORRESPONDS WITH A SLIGHT UPTICK IN 1000-850MB RETURN FLOW. HOWEVER...A SHORTWAVE RIDGE ASCENDING INTO THE LARGER RIDGE WILL HELP KEEP HEIGHTS HIGH. AT THE SAME TIME...SURFACE HIGH PRESSURE TO OUR EAST WILL STILL EXTEND A TOUCH OF RIDGING INTO NORTHERN MI. FROM A CONCEPTUAL MODEL STANDPOINT...IT WILL BE DIFFICULT TO FIRE OFF CONVECTION IN THIS PATTERN UNTIL HEIGHTS ALOFT FALL. INDEED...THE MODELS ARE NOT INCLINED TO PROG MUCH IF ANY CAPE. 00Z NAM HAS A LATE-DAY AXIS OF A FEW HUNDRED J/KG OF MUCAPE... HUGGING THE LAKE MI COAST FROM LTL TRAV BAY SOUTH. THIS IS WHERE LAKE BREEZE CONVERGENCE AND MOISTURE POOLING WILL BE CONCENTRATED... THANKS TO A BACKGROUND LIGHT SE SYNOPTIC SURFACE WIND. EVEN SO...AN 82/65 PARCEL HAS ABOUT 50J/KG OF CIN TO OVERCOME...THANKS TO 700MB TEMPS AROUND 9C. SO WILL MAINTAIN A DRY FORECAST. CAN GENERALLY EXPECT PARTLY SUNNY SKIES...WILL SOME BUBBLY CU AND MID/HIGH DEBRIS CLOUDS (INSTABILITY WILL BE MUCH HIGHER W OF LAKE MI). MAX TEMPS UPPER 70S (EASTERN UPPER...AND NE LOWER COAST)...TO LOW/MID 80S (INTERIOR SW SECTIONS). SUN NIGHT/MONDAY...SUB-850MB FLOW MAINTAIN AN EASTERLY COMPONENT INTO THE EVENING...BEFORE VEERING S TO EVEN SSW OVERNIGHT. THAT WILL ALLOW A JUICIER AND POTENTIALLY UNSTABLE AIRMASS TO FINALLY MAKE INROADS. HOWEVER...THAT WILL BE SLOW AT 1ST...WITH PERHAPS WESTERN CHIP/MACK THE ONLY PLACE PROGGED TO SEE SOME CAPE ARRIVE BY MORNING. THIS COULD ALLOW CONVECTION ORIGINATING IN WI A CHANCE TO GRAZE BY THAT AREA OVERNIGHT. BUT...GIVEN THE MODELS TEND TO BE TOO QUICK TO BREAK DOWN RIDGING AND CIN...WILL MAINTAIN A DRY FORECAST FOR SUN NIGHT. DEEP MOISTURE/MODERATE INSTABILITY PLUME WILL VERY SLOWLY WORK IN FROM THE WNW MONDAY...AHEAD OF A COLD FRONT ADVANCING ACROSS WI. HEIGHTS/TEMPS ALOFT HERE REMAIN HIGH...BUT ACTIVITY SHOULD DEVELOP UPSTREAM IN WI AND MOVE E AND NE TOWARD WESTERN/NORTHERN SECTIONS...ESPECIALLY LATER IN THE DAY. WILL MAINTAIN CHANCE POPS BY AFTERNOON IN THE NW 2/3DS OF THE FORECAST AREA...INCLUDING HIGH CHANCE (50) POPS IN WESTERN CHIP/MACK. MIN TEMPS NEAR 60F TO THE MID 60S. MAX TEMPS NEAR 80 TO THE MID 80S...A FEW UPPER 80S POSSIBLE IN THE INTERIOR OF NORTHERN LOWER. DEW POINTS WILL BE RISING INTO THE MID AND UPPER 60S...SO IT WILL ALSO BE QUITE STICKY ON MONDAY. REST OF THE FORECAST...SHAPING UP FOR A FAVORABLE MCS PATTERN MID-WEEK. A STALLED FRONTAL ZONE (AND A WARM/HUMID AIRMASS) WILL BE JUST TO OUR SOUTH...WITH FAST ZONAL FLOW IN THE NORTHERN LAKES. CONSALL GRIDS ARE TRYING TO NUDGE US TOWARD LIKELY POPS IN SOME PERIODS. AM BACKING AWAY FROM THIS THINKING GIVEN THAT IT/S CONVECTION WE/RE TALKING ABOUT...AND PRECIP HAS UNDERPERFORMED OVER THE LAST WEEK OR SO. TEMPS WILL BE DRIFTING BACK TOWARD OR A BIT UNDER CLIMO BY LATE IN THE WORK WEEK...THOUGH PROBABLY NOT AS COOL AS THE GFS/MEX GUIDANCE ADVERTISES...AS THE ECMWF IS SLOWER AND LESS AMPLIFIED WITH THE UPPER TROF THAT PROGRESSES INTO THE PLAINS STATES MID/LATE WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 645 AM EDT SAT AUG 23 2014 FOG TO BURN OFF THIS MORNING...THEN VFR THRU THIS EVENING. SOME FOG AGAIN LATE TONIGHT. HUMID AIRMASS WILL REMAIN IN PLACE THIS WEEKEND. WITH LIGHT WINDS AT NIGHT...FOG HAS BEEN AN ISSUE...AND THAT WILL CONTINUE. PLN/APN GETTING THE WORST OF IT THIS MORNING...LIFR AT TIMES. THAT WILL ONLY LAST 1-2 HOURS PAST 12Z AT MOST. THEN VFR. LIFR FOG IS AGAIN LIKELY AT APN/PLN LATE TONIGHT...HAVE ADDED MVFR CONDITIONS TO MBL LATE AS WELL. LIGHT WINDS. && .MARINE... ISSUED AT 246 AM EDT SAT AUG 23 2014 OVER THE NEXT 48 HOURS, THE WINDS WILL SLOWLY INCREASE AND VEER FROM THE EAST TO THE SOUTH LOW PRESSURE NEAR COLORADO DEEPENS AND MOVES INTO NORTH DAKOTA. SO TODAY THROUGH SUNDAY NIGHT, WILL EXPECT THAT WINDS AND WAVES WILL REMAIN BELOW SMALL CRAFT CONDITIONS. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...ADAM SYNOPSIS...JZ SHORT TERM...JL LONG TERM...JZ AVIATION...JZ MARINE...JL
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1230 PM CDT SAT AUG 23 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 350 AM CDT SAT AUG 23 2014 WE HAVE BEEN WATCHING AN IMPRESSIVE THUNDERSTORM COMPLEX RACE NORTH ACROSS NEBRASKA OVERNIGHT IN ASSOCIATION WITH A SHORTWAVE ROTATING NNE AROUND THE BASE OF A DEEP TROUGH CENTERED OVER IDAHO. HOWEVER...DO NOT GET TOO EXCITED ABOUT THE PROSPECTS ABOUT ANYONE IN THE MPX CWA SEEING MUCH OF THIS PRECIP TODAY...AS THIS WAA PRECIP LOOKS TO LARGELY GO AROUND THE MPX CWA. MOST CAMS SHOW TWO CONCENTRATED AREAS THIS MORNING HEADING EAST ACROSS IOWA...WITH THE OTHER BATCH OF WIDESPREAD THUNDERSTORMS TO HEAD NORTH ACROSS THE DAKOTAS. THE IOWA AREA IS IN RESPONSE TO AIR GETTING FORCED UP OVER THE REMNANTS OF A COLD FRONT...WHICH AT 3 AM WAS LOCATED JUST SOUTH OF OMAHA TO THE QUAD CITIES...WHICH IS MORE OR LESS THE AXIS WHERE THE HRRR HAS A SWATH OF HIGHER QPF FALLING. THE DAKOTAS BULLSEYE IS RESPONSE THE NOSE OF A 40 KT ESE ORIENTED LLJ THAT WILL BE WORKING NORTH IN CONJUNCTION WITH THE STRONG SHORTWAVE CURRENTLY OVER CENTRAL NEB. WITH THAT SAID...ACTIVITY OUT THERE NOW LOOKS LIKE IT SHOULD HAVE ENOUGH MOMENTUM TO AT LEAST SNEAK UP TO AREAS SOUTH/WEST OF THE MN RIVER. OTHERWISE...FOR MUCH OF THE MPX AREA...THE BAND OF STORMS WE SEE COMING NORTH NOW WILL NOT DO MUCH MORE THAN BRING A BAND OF ALTOCU THROUGH THE AREA. FOR THIS AFTERNOON...ATTENTION TURNS TO THE SEVERE POTENTIAL OUT IN WRN MN. BY THE AFTERNOON...THE BROAD SFC CYCLONE CURRENTLY SPLAYED OUT ACROSS THE CENTRAL HIGH PLAINS WILL HAVE CONSOLIDATED INTO A 1000 MB LOW NEAR THE CENTRAL ND/SD BORDER. THIS WILL HELP PULL THE FRONT IN IOWA BACK NORTH AS A WARM...WITH IT PUSHING INTO SW MN AFTER 00Z. WILL HAVE TO WAIT A WHILE FOR SFC BASED CONVECTION TO FIRE GIVEN EXTENT OF RAIN/CLOUD COVER EXPECTED ACROSS THE DAKOTAS THIS MORNING..BUT EXPECT ENOUGH HEATING TO OCCUR THIS AFTERNOON TO ALLOW FOR STORMS TO DEVELOP NEAR THE SURGING WARM FRONT ALONG THE COTEAU IN SE SODAK AROUND 21Z...AS BOTH THE NMM/ARW SHOW. THIS ACTIVITY SHOULD THEN TRACK NNE...TOWARD WEST CENTRAL AND NORTHWEST MN DURING THE EVENING...AND IT IS THIS POTENTIAL ACTIVITY THAT GIVES US THE SLIGHT RISK FOR TODAY FROM THE SPC. CERTAINLY INSTABILITY AND SHEAR ARE ADEQUATE TO SUPPORT SURFACE BASED SUPERCELLS AND THEREFOR ALL MODES OF SEVERE WEATHER. HOWEVER...FOR AS FAR EAST AS MN...SHEAR VECTORS WILL BE MORE PARALLEL THAN PERPENDICULAR TO THE FORCING...WHICH WOULD FAVOR THE CONGEALING OF ACTIVITY INTO CLUSTERS/LINES...WHICH IS WHAT IS SEEN WITH NMM/ARW REFLECTIVITY FORECASTS. THIS WOULD FAVOR THE HIGHEST TORNADO THREAT BEING ACROSS THE DAKOTAS...WHERE STORMS ARE MORE LIKELY TO BE DISCRETE...WITH WRN MN DEALING MORE WITH A POTENTIAL WIND/HAIL THREAT. FROM THE FLOOD TREAT...PWATS WILL INCREASE BACK TO AROUND 1.75 INCHES...SO CERTAINLY WILL SEE HEAVY RAIN WITH THIS ACTIVITY. HOWEVER...CURRENT EXPECTATIONS ARE THAT ACTIVITY WILL BE PROGRESSIVE ENOUGH TO KEEP ANY CONCENTRATED SWATHS OF HIGH QPF DOWN IN THE 1-2 INCH RANGE AS OPPOSED TO BEING UP IN THE 3-6 INCH RANGE LIKE WE WERE SEEING LAST WEEK. FOR TONIGHT...BEST UPPER FORCING WILL BE STAYING NW OF THE MPX CWA...SO ACTIVITY THAT MOVES INTO WRN MN WILL HEAD FOR NW/NC MN...SO CUT BACK CONSIDERABLY ON POPS...KEEPING THE ERN 2/3RDS OR SO OF THE CWA DRY. MAY STILL BE TOO FAR EAST WITH POPS TONIGHT...BUT WE SHOULD SEE SOMEWHAT OF AN EWRD PUSH WITH ACTIVITY TONIGHT AS COLD POOLS GET GENERATED. EVEN IF IT DOES NOT RAIN...IT WILL BE A MUGGY NIGHT...AS LOWER 70 DEWPS COME UP WITH THE WARM FRONT. WILL LIKELY MAKE IT TOUGH FOR MUCH OF THE MN CWA TO DIP BELOW 70 SUNDAY MORNING...WHICH WILL HAVE IMPLICATIONS ON THE POTENTIAL NEED FOR ANY HEAT HEADLINES SUNDAY. NOT WORRIED ABOUT FOG TONIGHT EITHER...AS GRADIENT WILL REMAIN STRONG THROUGH THE NIGHT...SO WILL BE ANOTHER NIGHT LIKE TONIGHT WHERE WE JUST WATCH ANY STRATUS THAT SURVIVES THE DAY TODAY EXPAND AGAIN OVERNIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 350 AM CDT SAT AUG 23 2014 THERE IS DEFINITELY SOME SPREAD IN THE MODEL GUIDANCE AS WE HEAD THROUGH THE LATTER PORTION OF THE FORECAST... BUT THE GENERAL SCENARIO SUGGESTS A TRANSITION FOR WESTERN RIDGE/EASTERN TROUGH TO MORE OF A ZONAL PATTERN BY THE END OF THE WEEK. THIS SHOULD ALLOW FOR TEMPERATURES TO TREND FROM ABOVE NORMAL TO NEAR NORMAL AS THE WEEK UNFOLDS... WITH PCPN CHANCES BEING A BIT TOUGH TO PIN DOWN DEPENDING UPON WHERE THE MAIN BAROCLINIC ZONE SETS UP. GIVEN THE SPREAD IN DETERMINISTIC AND ENSEMBLE GUIDANCE... A CONSENSUS APPROACH IS THE MOST SENSIBLE COURSE OF ACTION... SO STUCK CLOSE TO A MULTI-MODEL BLEND. THE MAIN FORECAST ISSUES LOOK TO BE THE POTENTIAL FOR EXCESSIVE HEAT/HUMIDITY SUNDAY... THEN THE POSSIBILITY OF SIGNIFICANT PCPN OVER THE SOUTHERN PORTION OF THE AREA LATE MONDAY THROUGH WEDNESDAY AS THE FRONTAL BOUNDARY HANGS UP SOMEWHERE NEAR THE MINNESOTA/IOWA BORDER. SUNDAY STILL LOOKS TO HAVE THE POTENTIAL FOR VERY WARM TEMPERATURES ACROSS THE AREA... ALONG WITH HIGH DEWPOINTS. AT THIS POINT... APPARENT TEMPERATURE FORECASTS PEAK AROUND 100 OVER A PORTION OF THE AREA SUNDAY AFTERNOON WITH FORECAST HIGHS IN THE LOW 90S AND DEWPOINTS NEAR 70. WET BULB GLOBE TEMPERATURES JUMP INTO THE LOWER TO MIDDLE 80S AS WELL... ALSO INDICATING THE POTENTIAL FOR HEAT RELATED ISSUES FOR PEOPLE WHO MAY BE OUTDOORS ON SUNDAY. THERE WILL CERTAINLY BE A SIGNIFICANT NUMBER OF PEOPLE OUTDOORS IN THE METRO AREA ON SUNDAY WITH THE GREAT MINNESOTA GET TOGETHER IN FULL SWING... SO THE POSSIBILITY OF EXCESSIVE HEAT/HUMIDITY WILL NEED TO BE MONITORED IN SUBSEQUENT FORECASTS. AT THIS POINT... THERE IS STILL SOME UNCERTAINTY IN CLOUD COVER AND WHETHER WE/LL MIX AS WELL AS SOME GUIDANCE SUGGESTS AND/OR SEE MORE LOW LEVEL EVAPORATIVE COOLING THAN ANTICIPATED. SO... WILL HIGHLIGHT THE POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK AND OTHER SERVICES... BUT HOLD OFF ON ANY ACTUAL HEADLINES AT THIS POINT. PCPN CHANCES ON SUNDAY LOOK TO BE CONFINED TO THE WESTERN/NORTHERN PORTION OF THE AREA UNTIL LATE AFTERNOON AND/OR EVENING WHEN THE COLD FRONT FINALLY STARTS TO WORK ITS WAY EAST ACROSS THE AREA. AT THAT POINT... THE MAIN LARGE SCALE FORCING WILL BE TO OUR NORTH... SO PCPN MAY BE SCATTERED IN NATURE WITH MORE WIDESPREAD ACTIVITY WITH THE SHORTWAVE AND TRIPLE-POINT TO OUR NORTH AND THE SECONDARY WARM ADVECTION/INSTABILITY NOSE TO OUR SOUTH. DEEP LAYER SHEAR WILL BE BEST TO OUR NORTH... SO ANY SEVERE POTENTIAL LOOKS TO BE CAPE- DRIVEN WITH MAINLY MULTI-CELL WIND/HAIL STORMS BEING THE CONCERN. CHANCES FOR PCPN WILL PUSH EAST SUNDAY NIGHT WITH THE FRONT... THEN WE/LL SEE HIGH PRESSURE BUILD OVER MUCH OF THE AREA. HOWEVER... THE FRONTAL BOUNDARY LOOKS TO HANG UP TO OUR SOUTH/EAST MONDAY INTO WEDNESDAY... NECESSITATING THE INCLUSION OF POPS OVER MUCH OF THE AREA DURING THAT TIME FRAME... WITH BETTER CHANCES SOUTH AND LOW CHANCES NORTH. THE FAR SOUTHERN PORTION OF THE AREA HAS SOME POTENTIAL TO SEE SIGNIFICANT RAINFALL OVER THAT PERIOD OF TIME... BUT MUCH WILL DEPEND ON WHERE SUCCESSIVE ROUNDS OF SHRA/TSRA DECIDE TO TRACK... AND IT IS TOO EARLY TO GET A GOOD HANDLE ON THAT EVOLUTION. WE SHOULD SEE HIGH PRESSURE... SUBSIDENCE... AND DRIER AIR WORK INTO THE ENTIRE AREA FROM THE NORTHWEST WEDNESDAY NIGHT THROUGH THE REMAINDER OF THE FORECAST PERIOD... WITH DRY WEATHER PREDOMINATING. HOWEVER... THE 00Z ECMWF IS A BIT SLOWER IN SHOWING THIS EVOLUTION IN COMPARISON TO ITS PREVIOUS RUNS OR THE 00Z GFS... SO WE/LL NEED TO SEE HOW THINGS EVOLVE IN SUBSEQUENT FORECASTS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1212 PM CDT SAT AUG 23 2014 NORTHERN EDGE OF DISSIPATING MCS OVER EASTERN IOWA CLIPPED KMSP AROUND NOON. LIGHT -SHRA INDICATED. THIS CONTINUES TO MOVE EAST AND IF MAY AFFECT KEAU EARLY. INCLUDED VCSH FOR THAT. COMPLICATED SCENARIO DEVELOPING WITH THE UPPER TROUGH MOVING THROUGH THE DAKOTAS. HIRES MODELS ARE PICKING UP ON SOME ACCAS LIFITNG OUT OF SOUTHEAST SODAK. THEY DEVELOP SOME ISOLD TSRA INTO SW MN DURING THE AFTERNOON...AND DISSIPATE LATE AFTERNOON INTO SC MN. WONT MENTION THIS ACTIVITY AT TAF SITE FOR NOW. LOWER IFR CLOUDS REMAIN LOCKED OVER CENTRAL MN WITH SOME EROSION NOTED INTO SC MN. THIS MAY WORK N-NE INTO THE AFTERNOON IN THE WAKE OF THE IOWA MCS. WILL TREND VFR THROUGH ABOUT 00Z MOST AREAS. EXPECT THUNDER TO DEVELOP AROUND 00Z IN EASTERN SODAK AND LIT NORTHEAST OVER WESTERN AND CENTRAL MN THROUGH THE NIGHT. HEAVY RAIN/POSSIBLE SEVERE INTO FAR WESTERN MN THROUGH ABOUT 06Z OR SO. WILL DROP CIGS AGAIN TO IFR OVERNIGHT AS WARM FRONT LIFTS OVER THE AREA. WILL MENTION MAINLY 3-5SM BR WITH IFR CIGS. EXPECT SLOW IMPROVEMENT AGAIN INTO SATURDAY MORNING...SIMILAR TO PREVIOUS FORECAST TREND. INCREASING GRADIENT AHEAD OF FRONT SHOULD YIELD SOME STRONG SE-S SOUTH WINDS WITH FROPA SATURDAY. KMSP...-SHRA/SPINKLES EXITING KMSP NOW. NEXT THREAT MOVES IN AFTER 05Z WITH A PROB30 FOR THUNDER INDICATED THROUGH 08Z. CIGS EXPECTED TO DROP OFF TO IFR LATE WITH IMPROVING CONDITIONS TO MVFR BY MIDE/LATE SUNDAY MORNING. EAST TO SOUTHEAST WINDS AHEAD OF WARM FRONT...WITH WINDS BECOMING MORE SOUTHERLY BY LATE SUNDAY MORNING OR EARLY SUNDAY AFTERNOON. SPEEDS AREA EXPECTED TO REMAIN AROUND 10KTS INTO TONIGHT...INCREASING TO 10-14KTS SUNDAY MORNING. /OUTLOOK FOR KMSP/ SUN NIGHT...VFR. CHANCE MVFR/TSRA. S WINDS 10-14KTS BCMG W 5-10 KTS. MON...VFR. WINDS W 5-10 KTS. TUE...SHRA/TSRA AND MVFR LIKELY BY AFTERNOON. WINDS NE 5-10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM... AVIATION...DWE
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
612 AM CDT SAT AUG 23 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 350 AM CDT SAT AUG 23 2014 WE HAVE BEEN WATCHING AN IMPRESSIVE THUNDERSTORM COMPLEX RACE NORTH ACROSS NEBRASKA OVERNIGHT IN ASSOCIATION WITH A SHORTWAVE ROTATING NNE AROUND THE BASE OF A DEEP TROUGH CENTERED OVER IDAHO. HOWEVER...DO NOT GET TOO EXCITED ABOUT THE PROSPECTS ABOUT ANYONE IN THE MPX CWA SEEING MUCH OF THIS PRECIP TODAY...AS THIS WAA PRECIP LOOKS TO LARGELY GO AROUND THE MPX CWA. MOST CAMS SHOW TWO CONCENTRATED AREAS THIS MORNING HEADING EAST ACROSS IOWA...WITH THE OTHER BATCH OF WIDESPREAD THUNDERSTORMS TO HEAD NORTH ACROSS THE DAKOTAS. THE IOWA AREA IS IN RESPONSE TO AIR GETTING FORCED UP OVER THE REMNANTS OF A COLD FRONT...WHICH AT 3 AM WAS LOCATED JUST SOUTH OF OMAHA TO THE QUAD CITIES...WHICH IS MORE OR LESS THE AXIS WHERE THE HRRR HAS A SWATH OF HIGHER QPF FALLING. THE DAKOTAS BULLSEYE IS RESPONSE THE NOSE OF A 40 KT ESE ORIENTED LLJ THAT WILL BE WORKING NORTH IN CONJUNCTION WITH THE STRONG SHORTWAVE CURRENTLY OVER CENTRAL NEB. WITH THAT SAID...ACTIVITY OUT THERE NOW LOOKS LIKE IT SHOULD HAVE ENOUGH MOMENTUM TO AT LEAST SNEAK UP TO AREAS SOUTH/WEST OF THE MN RIVER. OTHERWISE...FOR MUCH OF THE MPX AREA...THE BAND OF STORMS WE SEE COMING NORTH NOW WILL NOT DO MUCH MORE THAN BRING A BAND OF ALTOCU THROUGH THE AREA. FOR THIS AFTERNOON...ATTENTION TURNS TO THE SEVERE POTENTIAL OUT IN WRN MN. BY THE AFTERNOON...THE BROAD SFC CYCLONE CURRENTLY SPLAYED OUT ACROSS THE CENTRAL HIGH PLAINS WILL HAVE CONSOLIDATED INTO A 1000 MB LOW NEAR THE CENTRAL ND/SD BORDER. THIS WILL HELP PULL THE FRONT IN IOWA BACK NORTH AS A WARM...WITH IT PUSHING INTO SW MN AFTER 00Z. WILL HAVE TO WAIT A WHILE FOR SFC BASED CONVECTION TO FIRE GIVEN EXTENT OF RAIN/CLOUD COVER EXPECTED ACROSS THE DAKOTAS THIS MORNING..BUT EXPECT ENOUGH HEATING TO OCCUR THIS AFTERNOON TO ALLOW FOR STORMS TO DEVELOP NEAR THE SURGING WARM FRONT ALONG THE COTEAU IN SE SODAK AROUND 21Z...AS BOTH THE NMM/ARW SHOW. THIS ACTIVITY SHOULD THEN TRACK NNE...TOWARD WEST CENTRAL AND NORTHWEST MN DURING THE EVENING...AND IT IS THIS POTENTIAL ACTIVITY THAT GIVES US THE SLIGHT RISK FOR TODAY FROM THE SPC. CERTAINLY INSTABILITY AND SHEAR ARE ADEQUATE TO SUPPORT SURFACE BASED SUPERCELLS AND THEREFOR ALL MODES OF SEVERE WEATHER. HOWEVER...FOR AS FAR EAST AS MN...SHEAR VECTORS WILL BE MORE PARALLEL THAN PERPENDICULAR TO THE FORCING...WHICH WOULD FAVOR THE CONGEALING OF ACTIVITY INTO CLUSTERS/LINES...WHICH IS WHAT IS SEEN WITH NMM/ARW REFLECTIVITY FORECASTS. THIS WOULD FAVOR THE HIGHEST TORNADO THREAT BEING ACROSS THE DAKOTAS...WHERE STORMS ARE MORE LIKELY TO BE DISCRETE...WITH WRN MN DEALING MORE WITH A POTENTIAL WIND/HAIL THREAT. FROM THE FLOOD TREAT...PWATS WILL INCREASE BACK TO AROUND 1.75 INCHES...SO CERTAINLY WILL SEE HEAVY RAIN WITH THIS ACTIVITY. HOWEVER...CURRENT EXPECTATIONS ARE THAT ACTIVITY WILL BE PROGRESSIVE ENOUGH TO KEEP ANY CONCENTRATED SWATHS OF HIGH QPF DOWN IN THE 1-2 INCH RANGE AS OPPOSED TO BEING UP IN THE 3-6 INCH RANGE LIKE WE WERE SEEING LAST WEEK. FOR TONIGHT...BEST UPPER FORCING WILL BE STAYING NW OF THE MPX CWA...SO ACTIVITY THAT MOVES INTO WRN MN WILL HEAD FOR NW/NC MN...SO CUT BACK CONSIDERABLY ON POPS...KEEPING THE ERN 2/3RDS OR SO OF THE CWA DRY. MAY STILL BE TOO FAR EAST WITH POPS TONIGHT...BUT WE SHOULD SEE SOMEWHAT OF AN EWRD PUSH WITH ACTIVITY TONIGHT AS COLD POOLS GET GENERATED. EVEN IF IT DOES NOT RAIN...IT WILL BE A MUGGY NIGHT...AS LOWER 70 DEWPS COME UP WITH THE WARM FRONT. WILL LIKELY MAKE IT TOUGH FOR MUCH OF THE MN CWA TO DIP BELOW 70 SUNDAY MORNING...WHICH WILL HAVE IMPLICATIONS ON THE POTENTIAL NEED FOR ANY HEAT HEADLINES SUNDAY. NOT WORRIED ABOUT FOG TONIGHT EITHER...AS GRADIENT WILL REMAIN STRONG THROUGH THE NIGHT...SO WILL BE ANOTHER NIGHT LIKE TONIGHT WHERE WE JUST WATCH ANY STRATUS THAT SURVIVES THE DAY TODAY EXPAND AGAIN OVERNIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 350 AM CDT SAT AUG 23 2014 THERE IS DEFINITELY SOME SPREAD IN THE MODEL GUIDANCE AS WE HEAD THROUGH THE LATTER PORTION OF THE FORECAST... BUT THE GENERAL SCENARIO SUGGESTS A TRANSITION FOR WESTERN RIDGE/EASTERN TROUGH TO MORE OF A ZONAL PATTERN BY THE END OF THE WEEK. THIS SHOULD ALLOW FOR TEMPERATURES TO TREND FROM ABOVE NORMAL TO NEAR NORMAL AS THE WEEK UNFOLDS... WITH PCPN CHANCES BEING A BIT TOUGH TO PIN DOWN DEPENDING UPON WHERE THE MAIN BAROCLINIC ZONE SETS UP. GIVEN THE SPREAD IN DETERMINISTIC AND ENSEMBLE GUIDANCE... A CONSENSUS APPROACH IS THE MOST SENSIBLE COURSE OF ACTION... SO STUCK CLOSE TO A MULTI-MODEL BLEND. THE MAIN FORECAST ISSUES LOOK TO BE THE POTENTIAL FOR EXCESSIVE HEAT/HUMIDITY SUNDAY... THEN THE POSSIBILITY OF SIGNIFICANT PCPN OVER THE SOUTHERN PORTION OF THE AREA LATE MONDAY THROUGH WEDNESDAY AS THE FRONTAL BOUNDARY HANGS UP SOMEWHERE NEAR THE MINNESOTA/IOWA BORDER. SUNDAY STILL LOOKS TO HAVE THE POTENTIAL FOR VERY WARM TEMPERATURES ACROSS THE AREA... ALONG WITH HIGH DEWPOINTS. AT THIS POINT... APPARENT TEMPERATURE FORECASTS PEAK AROUND 100 OVER A PORTION OF THE AREA SUNDAY AFTERNOON WITH FORECAST HIGHS IN THE LOW 90S AND DEWPOINTS NEAR 70. WET BULB GLOBE TEMPERATURES JUMP INTO THE LOWER TO MIDDLE 80S AS WELL... ALSO INDICATING THE POTENTIAL FOR HEAT RELATED ISSUES FOR PEOPLE WHO MAY BE OUTDOORS ON SUNDAY. THERE WILL CERTAINLY BE A SIGNIFICANT NUMBER OF PEOPLE OUTDOORS IN THE METRO AREA ON SUNDAY WITH THE GREAT MINNESOTA GET TOGETHER IN FULL SWING... SO THE POSSIBILITY OF EXCESSIVE HEAT/HUMIDITY WILL NEED TO BE MONITORED IN SUBSEQUENT FORECASTS. AT THIS POINT... THERE IS STILL SOME UNCERTAINTY IN CLOUD COVER AND WHETHER WE/LL MIX AS WELL AS SOME GUIDANCE SUGGESTS AND/OR SEE MORE LOW LEVEL EVAPORATIVE COOLING THAN ANTICIPATED. SO... WILL HIGHLIGHT THE POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK AND OTHER SERVICES... BUT HOLD OFF ON ANY ACTUAL HEADLINES AT THIS POINT. PCPN CHANCES ON SUNDAY LOOK TO BE CONFINED TO THE WESTERN/NORTHERN PORTION OF THE AREA UNTIL LATE AFTERNOON AND/OR EVENING WHEN THE COLD FRONT FINALLY STARTS TO WORK ITS WAY EAST ACROSS THE AREA. AT THAT POINT... THE MAIN LARGE SCALE FORCING WILL BE TO OUR NORTH... SO PCPN MAY BE SCATTERED IN NATURE WITH MORE WIDESPREAD ACTIVITY WITH THE SHORTWAVE AND TRIPLE-POINT TO OUR NORTH AND THE SECONDARY WARM ADVECTION/INSTABILITY NOSE TO OUR SOUTH. DEEP LAYER SHEAR WILL BE BEST TO OUR NORTH... SO ANY SEVERE POTENTIAL LOOKS TO BE CAPE- DRIVEN WITH MAINLY MULTI-CELL WIND/HAIL STORMS BEING THE CONCERN. CHANCES FOR PCPN WILL PUSH EAST SUNDAY NIGHT WITH THE FRONT... THEN WE/LL SEE HIGH PRESSURE BUILD OVER MUCH OF THE AREA. HOWEVER... THE FRONTAL BOUNDARY LOOKS TO HANG UP TO OUR SOUTH/EAST MONDAY INTO WEDNESDAY... NECESSITATING THE INCLUSION OF POPS OVER MUCH OF THE AREA DURING THAT TIME FRAME... WITH BETTER CHANCES SOUTH AND LOW CHANCES NORTH. THE FAR SOUTHERN PORTION OF THE AREA HAS SOME POTENTIAL TO SEE SIGNIFICANT RAINFALL OVER THAT PERIOD OF TIME... BUT MUCH WILL DEPEND ON WHERE SUCCESSIVE ROUNDS OF SHRA/TSRA DECIDE TO TRACK... AND IT IS TOO EARLY TO GET A GOOD HANDLE ON THAT EVOLUTION. WE SHOULD SEE HIGH PRESSURE... SUBSIDENCE... AND DRIER AIR WORK INTO THE ENTIRE AREA FROM THE NORTHWEST WEDNESDAY NIGHT THROUGH THE REMAINDER OF THE FORECAST PERIOD... WITH DRY WEATHER PREDOMINATING. HOWEVER... THE 00Z ECMWF IS A BIT SLOWER IN SHOWING THIS EVOLUTION IN COMPARISON TO ITS PREVIOUS RUNS OR THE 00Z GFS... SO WE/LL NEED TO SEE HOW THINGS EVOLVE IN SUBSEQUENT FORECASTS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 544 AM CDT SAT AUG 23 2014 WINDS HAVE STAYED UP ENOUGH THROUGH THE NIGHT TO KEEP THIS MORNINGS ISSUE AS ONE OF STRATUS. GIVEN THE STRONGER WINDS...WE WILL SEE THESE CLOUDS CLEAR OUT MORE QUICKLY THAN WE DID YESTERDAY...BUT WILL STILL BE STUCK WITH IFR/MVFR CIGS THROUGH MUCH OF THE MORNING. AREA OF TSRA ENTERING SW MN WILL STRUGGLE TO MAKE IT MUCH FARTHER INTO THE STATE AS THE LLJ SLIDES MORE EAST ACROSS IOWA...KEEPING ACTIVITY TODAY MAINLY ALONG I-90...WITH A SECOND BATCH REMAINING OUT IN THE DAKOTAS. FOR THIS AFTERNOON...EXPECT STORMS TO DEVELOP ACROSS ERN SODAK AND HEAD NE TOWARD WEST CENTRAL MN. AXN LOOKS TO BE MOST SUSCEPTIBLE TO TSRA THIS EVENING...WITH BEST CHANCES REMAINING NORTH OF RWF AND WEST OF ALL OTHER TERMINALS. WILL ALSO HAVE A WARM FROM WORKING ACROSS SW MN OVERNIGHT...WITH THE THREAT FOR MORE IFR/LIFR STRATUS EXISTING AHEAD OF THIS BOUNDARY...WITH MAINLY MVFR HZ/BR IN THE WARM SECTOR. AT THIS POINT...ONLY RWF LOOKS TO DEFINITELY SEE THE WARM SECTOR...WHILE THE WI TERMINALS WILL REMAIN OUT AHEAD OF IT. AXN/STC/MSP WILL HAVE THE BOUNDARY NEARBY BY THE END OF THE NIGHT...BUT GIVEN THE DEGREE OF LOW LEVEL MOISTURE AROUND...DECIDED TO GO WITH THE IDEA OF ANOTHER ROUND OF LOW STRATUS TO START SUNDAY. KMSP...DESPITE WHAT RADAR LOOKS LIKE TO THE SW...CONFIDENT THAT MSP WILL SEE NOTHING MORE THAN SOME SPRINKLES THIS MORNING...AS THIS ACTIVITY IS STARTING TO FAVOR IOWA BASED ON CLOUD TOP TEMPERATURES WARMING OVER MN AND REMAINING COLD OVER IA. STRATUS WILL BE EASIER TO CLEAR OUT TODAY GIVEN THE STRONGER WINDS. TONIGHT...GIVEN WHERE FORCING IS GOING...CONFIDENT IN ANY TSRA ACTIVITY REMAINING NW OF MSP. WILL BE VERY MOIST AGAIN...AND GIVEN WHAT WE HAVE SEEN THE LAST FEW MORNINGS WITH STRATUS...DECIDED TO GO WITH THE TREND OF LOW STRATUS RETURNING TO START OF SUNDAY. HOWEVER...SUNDAY SHOULD SEE IT CLEAR OUT EVEN FASTER...AS A WARM FRONT LOOKS TO QUICKLY CLEAR THE FIELD IN THE MORNING...WITH A RATHER TOASTY WARM SECTOR MOVING IN IN ITS WAKE. /OUTLOOK FOR KMSP/ SUN NIGHT...VFR. CHANCE MVFR/TSRA. WINDS BCMG W 5-10 KTS. MON...VFR. WINDS W 5-10 KTS. TUE...SHRA/TSRA AND MVFR LIKELY BY AFTERNOON. WINDS NE 5-10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM... AVIATION...MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
354 AM CDT SAT AUG 23 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 350 AM CDT SAT AUG 23 2014 WE HAVE BEEN WATCHING AN IMPRESSIVE THUNDERSTORM COMPLEX RACE NORTH ACROSS NEBRASKA OVERNIGHT IN ASSOCIATION WITH A SHORTWAVE ROTATING NNE AROUND THE BASE OF A DEEP TROUGH CENTERED OVER IDAHO. HOWEVER...DO NOT GET TOO EXCITED ABOUT THE PROSPECTS ABOUT ANYONE IN THE MPX CWA SEEING MUCH OF THIS PRECIP TODAY...AS THIS WAA PRECIP LOOKS TO LARGELY GO AROUND THE MPX CWA. MOST CAMS SHOW TWO CONCENTRATED AREAS THIS MORNING HEADING EAST ACROSS IOWA...WITH THE OTHER BATCH OF WIDESPREAD THUNDERSTORMS TO HEAD NORTH ACROSS THE DAKOTAS. THE IOWA AREA IS IN RESPONSE TO AIR GETTING FORCED UP OVER THE REMNANTS OF A COLD FRONT...WHICH AT 3 AM WAS LOCATED JUST SOUTH OF OMAHA TO THE QUAD CITIES...WHICH IS MORE OR LESS THE AXIS WHERE THE HRRR HAS A SWATH OF HIGHER QPF FALLING. THE DAKOTAS BULLSEYE IS RESPONSE THE NOSE OF A 40 KT ESE ORIENTED LLJ THAT WILL BE WORKING NORTH IN CONJUNCTION WITH THE STRONG SHORTWAVE CURRENTLY OVER CENTRAL NEB. WITH THAT SAID...ACTIVITY OUT THERE NOW LOOKS LIKE IT SHOULD HAVE ENOUGH MOMENTUM TO AT LEAST SNEAK UP TO AREAS SOUTH/WEST OF THE MN RIVER. OTHERWISE...FOR MUCH OF THE MPX AREA...THE BAND OF STORMS WE SEE COMING NORTH NOW WILL NOT DO MUCH MORE THAN BRING A BAND OF ALTOCU THROUGH THE AREA. FOR THIS AFTERNOON...ATTENTION TURNS TO THE SEVERE POTENTIAL OUT IN WRN MN. BY THE AFTERNOON...THE BROAD SFC CYCLONE CURRENTLY SPLAYED OUT ACROSS THE CENTRAL HIGH PLAINS WILL HAVE CONSOLIDATED INTO A 1000 MB LOW NEAR THE CENTRAL ND/SD BORDER. THIS WILL HELP PULL THE FRONT IN IOWA BACK NORTH AS A WARM...WITH IT PUSHING INTO SW MN AFTER 00Z. WILL HAVE TO WAIT A WHILE FOR SFC BASED CONVECTION TO FIRE GIVEN EXTENT OF RAIN/CLOUD COVER EXPECTED ACROSS THE DAKOTAS THIS MORNING..BUT EXPECT ENOUGH HEATING TO OCCUR THIS AFTERNOON TO ALLOW FOR STORMS TO DEVELOP NEAR THE SURGING WARM FRONT ALONG THE COTEAU IN SE SODAK AROUND 21Z...AS BOTH THE NMM/ARW SHOW. THIS ACTIVITY SHOULD THEN TRACK NNE...TOWARD WEST CENTRAL AND NORTHWEST MN DURING THE EVENING...AND IT IS THIS POTENTIAL ACTIVITY THAT GIVES US THE SLIGHT RISK FOR TODAY FROM THE SPC. CERTAINLY INSTABILITY AND SHEAR ARE ADEQUATE TO SUPPORT SURFACE BASED SUPERCELLS AND THEREFOR ALL MODES OF SEVERE WEATHER. HOWEVER...FOR AS FAR EAST AS MN...SHEAR VECTORS WILL BE MORE PARALLEL THAN PERPENDICULAR TO THE FORCING...WHICH WOULD FAVOR THE CONGEALING OF ACTIVITY INTO CLUSTERS/LINES...WHICH IS WHAT IS SEEN WITH NMM/ARW REFLECTIVITY FORECASTS. THIS WOULD FAVOR THE HIGHEST TORNADO THREAT BEING ACROSS THE DAKOTAS...WHERE STORMS ARE MORE LIKELY TO BE DISCRETE...WITH WRN MN DEALING MORE WITH A POTENTIAL WIND/HAIL THREAT. FROM THE FLOOD TREAT...PWATS WILL INCREASE BACK TO AROUND 1.75 INCHES...SO CERTAINLY WILL SEE HEAVY RAIN WITH THIS ACTIVITY. HOWEVER...CURRENT EXPECTATIONS ARE THAT ACTIVITY WILL BE PROGRESSIVE ENOUGH TO KEEP ANY CONCENTRATED SWATHS OF HIGH QPF DOWN IN THE 1-2 INCH RANGE AS OPPOSED TO BEING UP IN THE 3-6 INCH RANGE LIKE WE WERE SEEING LAST WEEK. FOR TONIGHT...BEST UPPER FORCING WILL BE STAYING NW OF THE MPX CWA...SO ACTIVITY THAT MOVES INTO WRN MN WILL HEAD FOR NW/NC MN...SO CUT BACK CONSIDERABLY ON POPS...KEEPING THE ERN 2/3RDS OR SO OF THE CWA DRY. MAY STILL BE TOO FAR EAST WITH POPS TONIGHT...BUT WE SHOULD SEE SOMEWHAT OF AN EWRD PUSH WITH ACTIVITY TONIGHT AS COLD POOLS GET GENERATED. EVEN IF IT DOES NOT RAIN...IT WILL BE A MUGGY NIGHT...AS LOWER 70 DEWPS COME UP WITH THE WARM FRONT. WILL LIKELY MAKE IT TOUGH FOR MUCH OF THE MN CWA TO DIP BELOW 70 SUNDAY MORNING...WHICH WILL HAVE IMPLICATIONS ON THE POTENTIAL NEED FOR ANY HEAT HEADLINES SUNDAY. NOT WORRIED ABOUT FOG TONIGHT EITHER...AS GRADIENT WILL REMAIN STRONG THROUGH THE NIGHT...SO WILL BE ANOTHER NIGHT LIKE TONIGHT WHERE WE JUST WATCH ANY STRATUS THAT SURVIVES THE DAY TODAY EXPAND AGAIN OVERNIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 350 AM CDT SAT AUG 23 2014 THERE IS DEFINITELY SOME SPREAD IN THE MODEL GUIDANCE AS WE HEAD THROUGH THE LATTER PORTION OF THE FORECAST... BUT THE GENERAL SCENARIO SUGGESTS A TRANSITION FOR WESTERN RIDGE/EASTERN TROUGH TO MORE OF A ZONAL PATTERN BY THE END OF THE WEEK. THIS SHOULD ALLOW FOR TEMPERATURES TO TREND FROM ABOVE NORMAL TO NEAR NORMAL AS THE WEEK UNFOLDS... WITH PCPN CHANCES BEING A BIT TOUGH TO PIN DOWN DEPENDING UPON WHERE THE MAIN BAROCLINIC ZONE SETS UP. GIVEN THE SPREAD IN DETERMINISTIC AND ENSEMBLE GUIDANCE... A CONSENSUS APPROACH IS THE MOST SENSIBLE COURSE OF ACTION... SO STUCK CLOSE TO A MULTI-MODEL BLEND. THE MAIN FORECAST ISSUES LOOK TO BE THE POTENTIAL FOR EXCESSIVE HEAT/HUMIDITY SUNDAY... THEN THE POSSIBILITY OF SIGNIFICANT PCPN OVER THE SOUTHERN PORTION OF THE AREA LATE MONDAY THROUGH WEDNESDAY AS THE FRONTAL BOUNDARY HANGS UP SOMEWHERE NEAR THE MINNESOTA/IOWA BORDER. SUNDAY STILL LOOKS TO HAVE THE POTENTIAL FOR VERY WARM TEMPERATURES ACROSS THE AREA... ALONG WITH HIGH DEWPOINTS. AT THIS POINT... APPARENT TEMPERATURE FORECASTS PEAK AROUND 100 OVER A PORTION OF THE AREA SUNDAY AFTERNOON WITH FORECAST HIGHS IN THE LOW 90S AND DEWPOINTS NEAR 70. WET BULB GLOBE TEMPERATURES JUMP INTO THE LOWER TO MIDDLE 80S AS WELL... ALSO INDICATING THE POTENTIAL FOR HEAT RELATED ISSUES FOR PEOPLE WHO MAY BE OUTDOORS ON SUNDAY. THERE WILL CERTAINLY BE A SIGNIFICANT NUMBER OF PEOPLE OUTDOORS IN THE METRO AREA ON SUNDAY WITH THE GREAT MINNESOTA GET TOGETHER IN FULL SWING... SO THE POSSIBILITY OF EXCESSIVE HEAT/HUMIDITY WILL NEED TO BE MONITORED IN SUBSEQUENT FORECASTS. AT THIS POINT... THERE IS STILL SOME UNCERTAINTY IN CLOUD COVER AND WHETHER WE/LL MIX AS WELL AS SOME GUIDANCE SUGGESTS AND/OR SEE MORE LOW LEVEL EVAPORATIVE COOLING THAN ANTICIPATED. SO... WILL HIGHLIGHT THE POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK AND OTHER SERVICES... BUT HOLD OFF ON ANY ACTUAL HEADLINES AT THIS POINT. PCPN CHANCES ON SUNDAY LOOK TO BE CONFINED TO THE WESTERN/NORTHERN PORTION OF THE AREA UNTIL LATE AFTERNOON AND/OR EVENING WHEN THE COLD FRONT FINALLY STARTS TO WORK ITS WAY EAST ACROSS THE AREA. AT THAT POINT... THE MAIN LARGE SCALE FORCING WILL BE TO OUR NORTH... SO PCPN MAY BE SCATTERED IN NATURE WITH MORE WIDESPREAD ACTIVITY WITH THE SHORTWAVE AND TRIPLE-POINT TO OUR NORTH AND THE SECONDARY WARM ADVECTION/INSTABILITY NOSE TO OUR SOUTH. DEEP LAYER SHEAR WILL BE BEST TO OUR NORTH... SO ANY SEVERE POTENTIAL LOOKS TO BE CAPE- DRIVEN WITH MAINLY MULTI-CELL WIND/HAIL STORMS BEING THE CONCERN. CHANCES FOR PCPN WILL PUSH EAST SUNDAY NIGHT WITH THE FRONT... THEN WE/LL SEE HIGH PRESSURE BUILD OVER MUCH OF THE AREA. HOWEVER... THE FRONTAL BOUNDARY LOOKS TO HANG UP TO OUR SOUTH/EAST MONDAY INTO WEDNESDAY... NECESSITATING THE INCLUSION OF POPS OVER MUCH OF THE AREA DURING THAT TIME FRAME... WITH BETTER CHANCES SOUTH AND LOW CHANCES NORTH. THE FAR SOUTHERN PORTION OF THE AREA HAS SOME POTENTIAL TO SEE SIGNIFICANT RAINFALL OVER THAT PERIOD OF TIME... BUT MUCH WILL DEPEND ON WHERE SUCCESSIVE ROUNDS OF SHRA/TSRA DECIDE TO TRACK... AND IT IS TOO EARLY TO GET A GOOD HANDLE ON THAT EVOLUTION. WE SHOULD SEE HIGH PRESSURE... SUBSIDENCE... AND DRIER AIR WORK INTO THE ENTIRE AREA FROM THE NORTHWEST WEDNESDAY NIGHT THROUGH THE REMAINDER OF THE FORECAST PERIOD... WITH DRY WEATHER PREDOMINATING. HOWEVER... THE 00Z ECMWF IS A BIT SLOWER IN SHOWING THIS EVOLUTION IN COMPARISON TO ITS PREVIOUS RUNS OR THE 00Z GFS... SO WE/LL NEED TO SEE HOW THINGS EVOLVE IN SUBSEQUENT FORECASTS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1047 PM CDT FRI AUG 22 2014 LINGERING MVFR CEILINGS OVER NERN PORTIONS OF THE COVERAGE AREA SLOWLY RECEDED NE THIS EVE BUT STILL HELD OVER KRNH WHILE THE REMAINING TAF SITES HELD IN VFR. BY LATE EVENING...THE PLENTIFUL LOW LEVEL MOISTURE AND LIGHT WINDS WILL AGAIN COMBINE TO PRODUCE IFR-OR-LOWER CONDITIONS...MAINLY DUE TO CEILINGS BUT ALSO POTENTIALLY FOG FOR THE USUAL SUSPECTS /A.K.A. KSTC...KRNH AND KEAU/. HAVE MAINTAINED THIS THINKING IN THE 00Z TAFS WITH THE WORST CONDITIONS MAINLY BETWEEN 08Z-14Z SAT. CONDS THEN LOOK TO SLOWLY IMPROVE THRU THE MRNG HOURS. ONE OTHER COMPLICATION IS THE POTENTIAL DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS/TSTMS OVER ERN SD/ERN NE/WRN IA THAT WILL SPREAD INTO SWRN MN BY AROUND DAYBREAK THRU LATE MRNG. THIS WOULD AFFECT KRWF-KAXN-KSTC LATE MRNG INTO THE EARLY AFTN. TOO EARLY ATTM TO DETERMINE FLIGHT COND DETERIORATION BUT WILL FOR NOW SHOW PREVAILING PRECIP AT THE WRN TAF SITES. BY LATE EVENING...THE PLENTIFUL LOW LEVEL MOISTURE AND LIGHT WINDS WILL AGAIN COMBINE TO PRODUCE IFR- OR-LOWER CONDITIONS...MAINLY DUE TO CEILINGS BUT ALSO POTENTIALLY FOG FOR THE USUAL SUSPECTS /A.K.A. KSTC...KRNH AND KEAU/. HAVE MAINTAINED THIS THINKING IN THE 00Z TAFS WITH THE WORST CONDITIONS MAINLY BETWEEN 08Z-14Z SAT. CONDS THEN LOOK TO SLOWLY IMPROVE THRU THE MRNG HOURS. ONE OTHER COMPLICATION IS THE POTENTIAL DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS/TSTMS OVER ERN SD/ERN NE/WRN IA THAT WILL SPREAD INTO SWRN MN BY AROUND DAYBREAK THRU LATE MRNG. THIS WOULD AFFECT KRWF-KAXN-KSTC LATE MRNG INTO THE EARLY AFTN. TOO EARLY ATTM TO DETERMINE FLIGHT COND DETERIORATION BUT WILL FOR NOW SHOW PREVAILING PRECIP AT THE WRN TAF SITES. KMSP...CONDS BOUNCED BETWEEN VFR AND MVFR FOR MUCH OF THE EVENING...FINALLY HOLDING AT VFR COMING INTO THE 06Z INITIALIZATION TIME. AM STILL LOOKING FOR CONDS TO DROP TO SUB-1700 FT CEILINGS LATER TONIGHT AND HOLDING THERE THRU THE EARLY MRNG HRS. IFR CONDS THEN SETTLE IN CLOSE TO DAYBREAK BUT AM NOT XPCTG MUCH OF A VSBY RESTRICTION FROM VFR...JUST INTO MVFR. THE IFR CIGS WILL THEN LIKELY LAST THRU LATE MRNG TO AROUND MIDDAY...WITH VFR CONDS EXPECTED TMRW AFTN. DEGRADED CONDS EXPECTED AGAIN SAT EVENING...BUT AM ONLY ADVERTISING MVFR CIGS ATTM AND THIS DEGRADATION MAY BE LATER THAN ADVERTISED. /OUTLOOK FOR KMSP/ SUN...VFR. MVFR/TSRA POSSIBLE EVENING/OVERNIGHT. WINDS S10G20 KTS. MON...VFR. WINDS W 5-10 KTS. TUE...MAINLY VFR. CHC MVFR IN TSRA. WINDS NE 5-10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...MPG LONG TERM... AVIATION...JPC
AREA FORECAST DISCUSSION
NWS BILLINGS MT
1010 PM MDT FRI AUG 22 2014 .UPDATE... HAVE ISSUED A FLOOD WATCH FOR FAR SE MT AS ROUNDS OF HEAVY RAIN/EMBEDDED TSTMS EXPECTED TO LAST THROUGH THE NIGHT AND INTO SATURDAY...AS MONSOONAL ENERGY LIFTS UP THE HIGH PLAINS. A LONE SEVERE STORM IMPACTED SOUTHEAST MT A LITTLE WEST OF BROADUS EARLIER THIS EVENING. THIS HAS DISSIPATED AND CONVECTION IS FOCUSED IN SOUTHERN CARTER COUNTY NOW...AND IS NOT EXPECTED TO BECOME SEVERE. SHOWER ACTIVITY IS GRADUALLY BECOMING MORE WIDESPREAD ACROSS THE CWA IN RESPONSE TO INCREASING LARGE SCALE ASCENT WITH DEEP TROF DIGGING INTO IDAHO. LATEST H3 ANALYSIS SHOWS A VERY IMPRESSIVE 100 KT JET FROM OREGON INTO NEVADA...WITH STRONG DIFFLUENCE SHOWN ON SATELLITE IMAGERY FROM UTAH INTO SOUTHEAST IDAHO. ASCENT FROM THE UPPER LOW WILL ONLY INCREASE THROUGH THE NIGHT...AND IN FACT PER LATEST BLX VAD WINDS WE ARE SEEING EASTERLY UPSLOPE WINDS THROUGH 10KFT NOW. VERY IMPRESSIVE DYNAMICS FOR THE THIRD WEEK IN AUGUST. THERE REMAINS SOME UNCERTAINTY REGARDING TRACK OF MID LEVEL LOW BY EARLY SATURDAY MORNING WITH THE LATEST RAP SHOWING A WEAK 700MB LOW JUST NORTH OF BILLINGS...AND THIS IS NOT TOO DISSIMILAR TO THE NEW 00Z NAM...WITH THE GFS BEING A BIT FURTHER NORTH. SO AFTER A GOOD PERIOD OF RAIN TONIGHT WE MAY SEE THE HEAVIER PCPN SHIFT TO MAINLY OUR NORTH AND EAST PARTS FOR TOMORROW. THAT BEING SAID... RAP SHOWS 300MB LOW OVER SOUTHEAST IDAHO SATURDAY MORNING WHICH PUTS OUR AREA IN A VERY DIFFLUENT FLOW ALOFT...SO FEEL EVEN WITH SOME DEGREE OF LOW LEVEL DOWNSLOPING BY SATURDAY MORNING WE WILL STILL SEE ENOUGH ASCENT FOR SHOWERS IN THE BILLINGS AREA. INSTABILITY SHOULD REMAIN GREAT ENOUGH FOR EMBEDDED SCATTERED THUNDERSTORMS IN OUR EAST...OTHERWISE WE ARE LOOKING AT SHOWERS W/ ONLY ISOLD TSTMS THROUGH TOMORROW. FOR THE UPDATE HAVE RAISED POPS A BIT MORE ACROSS MUCH OF THE AREA TONIGHT AND SATURDAY. OVERALL FORECAST REMAINS ON TRACK. ITS GOING TO BE WET FOLKS. JKL && .SHORT TERM...VALID FOR SAT AND SUN... BROAD UPPER TROUGH OVER THE PACIFIC NW WILL CONTINUE TO PRODUCE AN UNUSUALLY COOL AND WET PERIOD ACROSS OUR REGION THE NEXT COUPLE OF DAYS. IF I WERE TO PICK A WETTEST PERIOD...IT WOULD BE TONIGHT INTO SATURDAY MORNING AS PLENTY OF LIFT IS PROGGED OVER OUR FORECAST AREA. ASSOCIATED JET DYNAMICS AND STRONG ISENTROPIC LIFT OUT IN FRONT OF THE UPPER TROUGH WILL LIKELY PRODUCE WIDESPREAD RAIN AND EMBEDDED THUNDER OVER THE AREA. SOME DISCRETE STRONG THUNDERSTORM CELLS ARE ALSO POSSIBLE FROM SHERIDAN TO CARTER COUNTY THIS EVENING AS EFFECTIVE SHEAR INCREASES ACROSS THIS AREA WITH A JET STREAK ALOFT. ONE OR TWO STRONG TO SEVERE STORMS ARE POSSIBLE IN THIS AREA DUE TO THE INCREASING POSSIBILITY OF SUSTAINED UPDRAFTS. LOOK FOR A VERY MOIST ATMOSPHERE WITH AREAS OF FOG AND LIGHT RAIN OVERNIGHT. SATURDAY...NEGATIVE TILT TROUGH WORKS INTO THE REGION FROM THE WEST AND MAY PRODUCE SOME STRONG TO SEVERE STORMS IN THE SE CORNER OF THE STATE DUE TO STRONG SHEAR AND INSTABILITY/LIFT. SEVERAL POCKETS OF LIFT WILL PRODUCE AREAS OF RAIN...MAINLY OVER THE NORTHERN AND EASTERN ZONES THROUGH SATURDAY. BY SATURDAY EVENING AS THE UPPER LOW MOVES OVER THERE IS SOME HINT OF DOWNSLOPE DRYING FROM HARLOWTON TO YELLOWSTONE COUNTY DUE TO NORTH/NORTHWEST FLOW WRAPPING AROUND THE LOW PRESSURE SYSTEM. THE ECMWF WANTS TO KEEP A CLOSED UPPER LOW OVER SE MONTANA WHILE THE GFS LIFTS THE SYSTEM NORTH. THE ECMWF VERSION IS MUCH WETTER THAN THE GFS. THERE IS NO REAL WAY TO DISCERN WHICH SOLUTION IS MOST ACCURATE AT THIS TIME ...THOUGH THE GFS HAS SUPPORT FROM THE NAM...AND GFS ENSEMBLE SPREADS ARE NOT THAT WIDE. THEREFORE...I HAVE BLENDED THE WET/DRY SOLUTIONS BUT LEANED A BIT MORE ON THE LESS WET GFS SOLUTION GOING INTO SUNDAY. LOOK FOR A BLUSTERY SATURDAY NIGHT AND SUNDAY WITH NORTH WINDS 15 TO 25 MPH COMBINED WITH THE RAINY CONDITIONS. BY SUNDAY NIGHT THE UPPER LOW IS TRACKING ACROSS NORTH DAKOTA WITH A MID LEVEL ZONAL FLOW SPREADING OVER MONTANA AND GENERALLY BRINGING MOST OF THE PRECIPITATION TO AN END OVER OUR FORECAST AREA. BT .LONG TERM...VALID FOR MON...TUE...WED...THU...FRI... MINIMAL UPDATES THIS AFTERNOON FOR THE INHERITED EXTENDED FORECAST...WITH MODELS IN GOOD AGREEMENT THROUGHOUT THE PERIOD. A SECONDARY LOBE OF THE BROAD UPPER TROF IS STILL VERY SLOW TO PUSH OFF TO THE EAST. THE TROF AXIS WILL BEGIN SLOW PROGRESSION EASTWARD MONDAY. THIS WILL BRING ANOTHER ROUND OF PRECIP THROUGH THE REGION BEGINNING MONDAY...AND LINGERING THROUGH MUCH OF TUESDAY. THE DYNAMICS FOR THIS SYSTEM APPEARS MUCH WEAKER...SO EXPECT SHOWERS AND THUNDERSTORMS TO BE MORE SCATTERED IN NATURE. THE SLOW MOVEMENT OF THE TROF WILL KEEP TEMPS WELL BELOW SEASONAL AVERAGE...WITH HIGHS IN THE LOW TO MID 70S EACH DAY. AN UPPER LEVEL RIDGE BEGINS BUILDING INTO THE REGION OVERNIGHT TUESDAY NIGHT...AND IS THEN FOLLOWED BY ZONAL FLOW DEVELOPING LATE THURSDAY. THEREFORE EXPECT WARMER AND DRIER CONDITIONS TO PREVAIL THROUGH THE REMAINDER OF THE EXTENDED PERIOD. TEMPERATURES WILL SLOWLY TREND UPWARD...BUT GENERALLY REMAIN AROUND SEASONAL AVERAGE. AAG && .AVIATION... SCATTERED SHOWERS...AND A FEW THUNDERSTORMS...WILL IMPACT ALL TERMINALS TONIGHT. EXPECTING MVFR AND IFR CONDITIONS WITH OCCASIONAL HEAVY RAINFALL THROUGH THE NIGHTTIME HOURS. CEILINGS WILL REMAIN LOW UNTIL THE DAYBREAK HOURS. SINGER && .PRELIMINARY POINT TEMP/POPS... SAT SUN MON TUE WED THU FRI ----------------------------------------------------------- BIL 056/063 049/065 048/071 050/075 053/082 057/087 061/085 +8/T 44/T 23/T 32/T 11/U 01/U 11/U LVM 051/060 045/064 042/070 044/075 048/083 051/086 051/084 +8/T 43/T 25/T 52/T 11/B 01/U 12/T HDN 057/068 050/066 046/074 050/077 051/083 055/088 059/088 98/T 55/T 13/T 32/T 11/U 01/U 11/U MLS 060/067 052/062 047/071 051/074 053/082 057/087 062/090 ++/T 86/T 22/T 22/T 11/U 11/U 11/B 4BQ 060/071 051/064 046/071 052/073 051/081 056/087 060/089 89/T 63/T 22/T 33/T 11/U 11/U 11/U BHK 056/066 050/061 046/069 047/071 048/078 053/083 059/086 9+/T 86/T 22/T 23/T 11/U 11/U 11/B SHR 055/070 047/065 044/073 048/074 048/081 051/087 055/089 76/T 53/T 13/T 43/T 11/U 01/U 11/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...FLOOD WATCH IN EFFECT THROUGH SATURDAY AFTERNOON FOR ZONES 32-33-36-37. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
553 PM CDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 313 PM CDT SAT AUG 23 2014 H5 ANALYSIS FROM THIS MORNING HAS RIDGING ACROSS THE MISSISSIPPI VALLEY FROM THE GULF COAST NWD INTO THE WESTERN GREAT LAKES. FURTHER EAST...DECENT SHORTWAVES WERE NOTED OVER LAKE ONTARIO AND NOVA SCOTIA. FURTHER WEST...A TANDEM OF SHORTWAVES WERE LOCATED OVER THE INTERMOUNTAIN WEST. THE FIRST OVER WESTERN COLORADO AND A SECOND OVER EASTERN IDAHO...WHILE ANOTHER SHORTWAVE WAS UPSTREAM OVER THE ALASKA PANHANDLE. WV IMAGERY AS OF 1 PM CDT...INDICATED SHORTWAVE ENERGY IN ASSOCIATION WITH THE WAVE OVER WESTERN COLORADO HAD BEGUN TO EMERGE ACROSS CENTRAL COLORADO AND HAS LED TO INCREASING CLOUDINESS ALONG THE FRONT RANGE OF COLORADO. OVER THE NEXT COUPLE OF HRS...SHRAS AND TSRAS ARE EXPECTED TO DEVELOP ON THE LEE SIDE OF THE ROCKIES INVOF THE FRONT RANGES OF COLORADO AND WYOMING. FURTHER WEST...A CLOSED LOW REMAINS IN PLACE OVER EASTERN IDAHO ATTM WITH A BROAD AREA OF CLOUDS AND SHOWERS ACROSS MONTANA...NORTH DAKOTA AND NORTHERN SOUTH DAKOTA. ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...ABUNDANT CLOUDINESS WAS PRESENT OVER MOST OF THE AREA WITH THE EXCEPTION OF FAR SWRN NEBRASKA AND THE EASTERN NEBRASKA PANHANDLE WHERE CLOUDS HAVE SCATTERED OUT OVER THE PAST 1 TO 2 HOURS. AT THE SURFACE...A TANDEM OF LOW PRESSURE CENTERS WERE PRESENT ACROSS SERN WYOMING AND A SECOND OVER SOUTH CENTRAL SD. A WARM FRONT EXTENDED FROM SERN WYOMING INTO EASTERN SOUTH DAKOTA...WHILE A COLD FRONT EXTENDED SSWD INTO THE CENTRAL ROCKIES. UNDER PARTLY TO MOSTLY CLOUDY SKIES...TEMPERATURES AS OF 3 PM CDT...RANGED FROM 72 AT AINSWORTH...TO 82 AT BROKEN BOW. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 313 PM CDT SAT AUG 23 2014 MODELS REMAIN IN GOOD AGREEMENT WITH THE PROJECTIONS OF A PV ANOMALY LIFTING NORTHEAST FROM FAR SOUTHWESTERN WYOMING TOWARD THE NORTHERN PLAINS THIS EVENING AND OVERNIGHT. RECENT OBSERVATIONS INDICATE THAT THE LOW STRATUS IS DISSIPATING EARLY THIS AFTERNOON...LEADING TO THE EVENTUAL DESTABILIZATION OF THE LOWER TROPOSPHERE. AS HEIGHTS FALL WITH THE APPROACH OF THE PV MAX/ATTENDANT COLD FRONT...STORMS ARE ANTICIPATED TO FORM INVOF OF THE HIGH PLAINS SURFACE LOW/FRONTAL BOUNDARY AND POSSIBLY DRIFT EAST ACROSS THE SANDHILLS REGION OF NEB OVERNIGHT. THE LATEST PROJECTIONS FROM THE RAP AND HRRR SHOWS THAT DESPITE THE MORNING CLOUDS...LOW TO MID LEVEL LAPSE RATES HAVE INCREASED SOME...YIELDING A WEAKLY UNSTABLE ATMOSPHERE ACROSS WESTERN PORTIONS OF THE CWA /CONTINUED CLEARING WILL ALLOW FOR FURTHER DESTABILIZATION/. THE PROJECTED INSTABILITY /UPWARDS TO 1000 J/KG ML CAPE/ COMBINED WITH 0-6KM BULK SHEAR OF 30KTS OR SO WILL PROMOTE THE POSSIBILITY OF STRONG TO LOW END SEVERE STORMS THIS EVENING AND OVERNIGHT. ANOTHER AREA TO WATCH FOR SEVERE STORMS WILL BE ACROSS NORTH CENTRAL NEBRASKA LATE THIS AFTERNOON AS A SECONDARY WARM FRONT LIFTS NORTH TOWARD THE SOUTHEAST SOUTH DAKOTA. ABUNDANT INSTABILITY AND SUFFICIENT SHEAR WOULD PROMOTE RAPID STORM DEVELOPMENT CAPABLE OF LARGE HAIL AND DAMAGING WIND GUSTS. THE HEAVY RAIN THREAT WILL BE NOTICEABLY LESS TONIGHT AS BUFR SOUNDINGS REVEAL A MUCH LESSER INFLUENCE FROM WARM RAIN PROCESSES...BUT WITH PWATS AT OR SLIGHTLY ABOVE AVERAGE...BRIEF HEAVY RAINFALL IS STILL POSSIBLE. THE COLD FRONT CLEARS THE CWA EARLY ON SUNDAY WITH RAIN CHANCES POSSIBLY LINGERING ACROSS OUR FAR EAST THROUGH 15Z...OTHERWISE A SLIGHTLY COOLER AIRMASS IS ANTICIPATED WITH HIGHS RANGING FROM THE MID 70S ACROSS OUR FAR NORTHWEST...TO LOW TO MID 80S SOUTH OF THE INTERSTATE 80 CORRIDOR. WITH MOISTURE LACKING AND A STABLE AIRMASS ANTICIPATED SUNDAY AFTERNOON...STORM CHANCES SHOULD BE KEPT AT BAY UNTIL AT LEAST 00Z MONDAY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 331 PM CDT SAT AUG 23 2014 SUNDAY NIGHT THROUGH TUESDAY...THE MAIN FORECASTING CHALLENGE CONTINUES TO BE PRECIPITATION CHANCES AND THE THREAT FOR HEAVY RAIN AS A TROUGH AND SEMI STATIONARY FRONTAL BOUNDARY PERSISTS ACROSS THE CENTRAL ROCKIES AND PLAINS DURING THE PERIOD. FOR SUNDAY NIGHT...AFTER RELATIVELY QUIET WEATHER CONDS SUNDAY...MID LEVEL WAA WILL INCREASE ALONG THE FRONT RANGE DURING THE EVENING...TRANSITIONING EAST ACROSS THE CENTRAL PLAINS OVERNIGHT SUNDAY NIGHT INTO EARLY MONDAY. AT THE SAME TIME...A NICE H250 JET STREAK WILL LIFT ACROSS NWRN NEBRASKA INTO SOUTH DAKOTA PLACING WESTERN AND NORTH CENTRAL NEBRASKA IN THE RIGHT REAR QUAD OF THIS FEATURE. ENHANCED LIFT ACROSS THE FORECAST AREA...WILL LEAD TO A SHARP INCREASE IN THE THREAT OF PCPN SUNDAY NIGHT INTO MONDAY. IN THE LOWER LEVELS...A FRONTAL BOUNDARY WILL BE ANCHORED ACROSS SRN NEBRASKA SUNDAY NIGHT WITH THE NOSE OF A H85 LOW LEVEL JET POSITIONED ACROSS SWRN NEBRASKA. INHERITED FCST HAD THE HIGHEST POPS ACROSS SRN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT INTO MONDAY MORNING AND APPEARS ON TRACK ATTM. PRECIPITATION CHANCES WILL DECREASE SOMEWHAT MONDAY AS MID LEVEL FORCING PUSHES EAST INTO THE MID MISSOURI VALLEY. BY MONDAY NIGHT...ANOTHER STRONG UPPER LEVEL DISTURBANCE WILL PUSH ACROSS THE CENTRAL PLAINS...LEADING TO INCREASED CHANCES FOR RAIN MONDAY NIGHT...AS WELL AS TUESDAY NIGHT. LOW LEVEL EASTERLY WINDS AND ABUNDANT MID AND UPPER LEVEL MOISTURE TRANSPORT FROM THE SOUTHWEST IN ASSOCIATION WITH HURRICANE MARIE COULD LEAD TO HEAVY RAIN ACROSS THE CENTRAL PLAINS BEGINNING MONDAY NIGHT AND POSSIBLY PERSISTING INTO TUESDAY NIGHT. FURTHER SUPPORT FOR HEAVY RAIN IS EVIDENT IN FCST PWATS RANGING FROM 1.5 TO 2.0 INCHES MONDAY NIGHT THROUGH TUESDAY NIGHT. WEDNESDAY THROUGH SATURDAY...LINGERING PCPN CHANCES ARE THE MAIN FORECAST CHALLENGE IN THE LONG RANGE PERIODS. BY WEDNESDAY INTO THURSDAY...THE PERSISTENT UPPER LEVEL TROUGH ACROSS THE ROCKIES...WILL CROSS THE CENTRAL PLAINS INTO THE MISSISSIPPI VALLEY. THE LATEST GFS SOLN IS 24 HRS FASTER COMPARED TO THE ECMWF IN LIFTING THIS FEATURE EAST OF THE AREA. THE GFS IS DRY AFTER WEDS WITH THE TROUGH OVER MISSOURI VALLEY BY 12Z THURSDAY...WHILE THE ECMWF HAS THIS FEATURE OVER THE SAME AREA BY 12Z FRIDAY. INHERITED FCST WAS DRY WEDS NIGHT AND INTRODUCED POPS FOR THIS PERIOD AS BOTH MODELS HAVE TRENDED SLOWER. WILL HOLD OFF ON INTRODUCING POPS FOR THURSDAY FOR NOW AND WAIT FOR THE MODELS TO COME INTO BETTER AGREEMENT. AFTER UNSEASONABLY COOL HIGHS IN THE 70S FOR WEDNESDAY AND THURSDAY...HIGHS WILL REBOUND BACK INTO THE 80S FOR THURSDAY AND FRIDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 553 PM CDT SAT AUG 23 2014 A PACIFIC COLD FRONT IS ENTERING WRN NEB THIS EVENING. THE FRONT IS EXPECTED TO BE THE FOCUS FOR CONTINUED TSTM DEVELOPMENT OVERNIGHT. STORM ACTIVITY IS EXPECTED TO DIMINISH IN COVERAGE ACROSS NCNTL NEB BY 12Z SUNDAY AND VFR IS EXPECTED THEREAFTER ALL AREAS. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CLB SHORT TERM...JACOBS LONG TERM...CLB AVIATION...CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
359 PM CDT SAT AUG 23 2014 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 345 PM CDT SAT AUG 23 2014 STUBBORN LOWER CLOUDS STILL HANGING ON ACROSS NORTHWEST PART OF THE FORECAST AREA. SULTRY AIRMASS TODAY AS WELL...WITH DEWPOINTS AROUND 70 SEVERAL LOCATIONS. MOST MODELS TRY TO PUMP IN SOME DRIER AIR FROM THE SOUTH THROUGH THIS EVENING...WITH THE HRRR MOST AGGRESSIVE. THAT COULD PROVIDE A LITTLE HUMIDITY RELIEF TO SOME SPOTS IN THE SOUTHERN/SOUTHEAST FORECAST AREA. AS WE WORK INTO TONIGHT...THE PROSPECT OF THUNDERSTORMS IS MUCH MUCH LOWER...BUT NOT NIL. A DECENT LOW LEVEL JET WILL DEVELOP AND THAT COULD SUSTAIN HIGH PLAINS CONVECTION...BUT ALSO SPARK A FEW OTHER ISOLATED SHOWERS AND STORMS. OVERALL COVERAGE SHOULD BE ISOLATED...BUT CAN NOT TOTALLY RULE IT OUT. SUNDAY SHOULD START WITH LINGERING MID/HIGH CLOUDS FROM LEFTOVER SHOWERS AND THUNDERSTORMS IN PARTS OF THE PLAINS. THESE MAY HOLD OVER INTO THE POST SUNRISE HOURS OVER NORTHERN PARTS OF THE FORECAST NEAR A FRONTAL BOUNDARY...BUT COVERAGE WILL BE SPARSE AND 20 PERCENT CHANCES REPRESENT RAIN RISK WELL. A WEAK FRONTAL BOUNDARY WILL ATTEMPT TO MOVE ACROSS THE FORECAST AREA SUNDAY. MODELS SEEM A BIT AGGRESSIVE...BUT SOMETIMES THAT DOES WORK OUT. EXPECT A SHIFTING WIND...AND THEN A DYING WIND AS THE FORECAST IS LEFT TO FLOUNDER IN THE SURFACE SURFACE WITH THE FRONT WEAKENING WITH TIME. THE WEAK NATURE OF THE FRONT AND SOME WARM MID LEVEL TEMPERATURES WILL PROBABLY KEEP ANY DEVELOPMENT OF THUNDERSTORMS NEAR OR ALONG THE FRONT VERY SPARSE AND TOWARD EVENING AT THE EARLIEST. HAVE KEPT SIMILAR IDEA OF LOWER DEWPOINTS BEHIND THE FRONTAL PASSAGE...BUT HAVE SOME DOUBT PLACES LIKE GRAND ISLAND AND HASTINGS COULD DROP TO A SUB-60 DEWPOINT LATE SUNDAY AFTERNOON. THAT WOULD BE NICE BUT WE WILL SEE. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 345 PM CDT SAT AUG 23 2014 UNSETTLED WEATHER CONDITIONS WILL CONTINUE THROUGH MUCH OF THE EXTENDED PERIODS AS THE LOCAL AREA WILL REMAIN UNDER THE INFLUENCE OF A LARGE TROUGH OF LOW PRESSURE ACROSS THE INTERMOUNTAIN WEST WITH WEST TO SOUTHWESTERLY FLOW PERSISTING ALOFT. EXPECT THE MAIN UPPER LEVEL LOW ACROSS THE DAKOTAS SUNDAY EVENING TO LIFT NORTHEAST...WITH A SECONDARY FRONTAL BOUNDARY PUSHING ACROSS THE LOCAL AREA. WHILE THIS FRONTAL BOUNDARY MAY PROVIDE THE TRIGGER FOR SOME ELEVATED CONVECTION ACROSS THE SOUTHEASTERN PORTIONS OF THE LOCAL AREA EARLY IN THE EVENING...EXPECT THE BETTER CHANCES TO SPREAD FROM WEST TO EAST AFTER MIDNIGHT AS A TRAILING MID LEVEL DISTURBANCE MOVES ACROSS THE LOCAL AREA FROM THE HIGH PLAINS AND A WEAK LOW LEVEL JET FOCUSES ITSELF ACROSS NORTH CENTRAL KANSAS. AS THIS FIRST UPPER LEVEL LOW TRACKS WELL INTO CANADA...EXPECT A SECOND UPPER LEVEL LOW TO SLIDE FROM THE PACIFIC NORTHWEST AND INTO THE INTERMOUNTAIN WEST BY MONDAY...MAINTAINING SOUTHWESTERLY ALOFT ACROSS THE REGION. WHILE CHANCES FOR PRECIPITATION WILL DECREASE SOME DURING THE DAY ON MONDAY...KEPT SOME SMALL POPS IN THE FORECAST AS THE OLD FRONTAL BOUNDARY WILL BE MEANDERING ACROSS THE REGION. THAT SAID...THE BETTER SHOT FOR MORE WIDESPREAD CONVECTION WILL BE MONDAY NIGHT...AS YET ANOTHER UPPER LEVEL DISTURBANCE IN SOUTHWESTERLY FLOW TRAVERSES THE REGION IN CONCERT WITH AN INCREASING LOW LEVEL JET AIMED ACROSS SOUTH CENTRAL NEBRASKA. WITH SEVERAL THOUSAND JOULES OF CAPE IN PLACE AND MODEST SHEAR VALUES FORECAST...EXPECT THE POTENTIAL FOR AN ACTIVE NIGHT ACROSS THE LOCAL AREA...ESPECIALLY FROM THE STATE LINE NORTH. DUE TO SOME DISCREPANCIES IN MODEL DATA... HOWEVER...ONLY WENT AHEAD AND ADVERTISED LIMITED SEVERE POTENTIAL FOR MONDAY NIGHT IN THE HWO. OTHERWISE...THUNDERSTORM ACTIVITY TUESDAY SHOULD ONCE AGAIN BE FOCUSED NEAR THE LOW LEVEL JET DURING THE EVENING AND OVERNIGHT HOURS...WITH A COLD FRONT EXPECTED TO BRING YET ANOTHER CHANCE FOR THUNDERSTORMS ACROSS THE LOCAL AREA WEDNESDAY AND WEDNESDAY NIGHT. WHILE A CHANCE FOR PRECIPITATION IS IN THE FORECAST SUNDAY THROUGH THURSDAY...AT THIS TIME THE BEST POTENTIAL FOR ANY SEVERE WEATHER APPEARS TO BE PRIMARILY DURING THE EVENING AND OVERNIGHT HOURS MONDAY THROUGH WEDNESDAY...WITH A COOLER...DRIER...AND MORE STABLE AIRMASS EXPECTED TO SETTLE IN ACROSS THE REGION TO END THE WEEK. HYDROLOGY WISE...DUE TO THE RECENT RAINFALL AND SATURATED SOILS ACROSS MUCH OF THE LOCAL AREA...CONTINUED WITH THE MENTION OF LOCALIZED FLOODING THE HWO IN THIS UNSETTLED PATTERN. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1235 PM CDT SAT AUG 23 2014 SLOWLY ERODING LOW CLOUDS OUT OF SOUTH CENTRAL NEBRASKA. GRAND ISLAND PRETTY MUCH IN THE CLEAR IT APPEARS...WHILE KEARNEY MAY SKIRT WITH SOME SCATTERED AFTERNOON CLOUDS BUT OVERALL TREND SHOULD BE CLEARING OUT. WINDS WILL CONTINUE TO INCREASE AHEAD OF DEEPENING LOW LEVEL TROUGH WITH GUSTS OVER 20 MPH NOT UNCOMMON. PRECIPITATION WHICH DEVELOPS TO THE WEST TONIGHT COULD MOVE INTO THE AREA LATE IN THE FORECAST...BUT WAS NOT CONFIDENT IN ITS COVERAGE TO ADD TO FORECAST AT THIS TIME. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...MORITZ LONG TERM...ROSSI AVIATION...NOAA/NWS/MORITZ
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
313 PM CDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 313 PM CDT SAT AUG 23 2014 H5 ANALYSIS FROM THIS MORNING HAS RIDGING ACROSS THE MISSISSIPPI VALLEY FROM THE GULF COAST NWD INTO THE WESTERN GREAT LAKES. FURTHER EAST...DECENT SHORTWAVES WERE NOTED OVER LAKE ONTARIO AND NOVA SCOTIA. FURTHER WEST...A TANDEM OF SHORTWAVES WERE LOCATED OVER THE INTERMOUNTAIN WEST. THE FIRST OVER WESTERN COLORADO AND A SECOND OVER EASTERN IDAHO...WHILE ANOTHER SHORTWAVE WAS UPSTREAM OVER THE ALASKA PANHANDLE. WV IMAGERY AS OF 1 PM CDT...INDICATED SHORTWAVE ENERGY IN ASSOCIATION WITH THE WAVE OVER WESTERN COLORADO HAD BEGUN TO EMERGE ACROSS CENTRAL COLORADO AND HAS LED TO INCREASING CLOUDINESS ALONG THE FRONT RANGE OF COLORADO. OVER THE NEXT COUPLE OF HRS...SHRAS AND TSRAS ARE EXPECTED TO DEVELOP ON THE LEE SIDE OF THE ROCKIES INVOF THE FRONT RANGES OF COLORADO AND WYOMING. FURTHER WEST...A CLOSED LOW REMAINS IN PLACE OVER EASTERN IDAHO ATTM WITH A BROAD AREA OF CLOUDS AND SHOWERS ACROSS MONTANA...NORTH DAKOTA AND NORTHERN SOUTH DAKOTA. ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...ABUNDANT CLOUDINESS WAS PRESENT OVER MOST OF THE AREA WITH THE EXCEPTION OF FAR SWRN NEBRASKA AND THE EASTERN NEBRASKA PANHANDLE WHERE CLOUDS HAVE SCATTERED OUT OVER THE PAST 1 TO 2 HOURS. AT THE SURFACE...A TANDEM OF LOW PRESSURE CENTERS WERE PRESENT ACROSS SERN WYOMING AND A SECOND OVER SOUTH CENTRAL SD. A WARM FRONT EXTENDED FROM SERN WYOMING INTO EASTERN SOUTH DAKOTA...WHILE A COLD FRONT EXTENDED SSWD INTO THE CENTRAL ROCKIES. UNDER PARTLY TO MOSTLY CLOUDY SKIES...TEMPERATURES AS OF 3 PM CDT...RANGED FROM 72 AT AINSWORTH...TO 82 AT BROKEN BOW. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 313 PM CDT SAT AUG 23 2014 MODELS REMAIN IN GOOD AGREEMENT WITH THE PROJECTIONS OF A PV ANOMALY LIFTING NORTHEAST FROM FAR SOUTHWESTERN WYOMING TOWARD THE NORTHERN PLAINS THIS EVENING AND OVERNIGHT. RECENT OBSERVATIONS INDICATE THAT THE LOW STRATUS IS DISSIPATING EARLY THIS AFTERNOON...LEADING TO THE EVENTUAL DESTABILIZATION OF THE LOWER TROPOSPHERE. AS HEIGHTS FALL WITH THE APPROACH OF THE PV MAX/ATTENDANT COLD FRONT...STORMS ARE ANTICIPATED TO FORM INVOF OF THE HIGH PLAINS SURFACE LOW/FRONTAL BOUNDARY AND POSSIBLY DRIFT EAST ACROSS THE SANDHILLS REGION OF NEB OVERNIGHT. THE LATEST PROJECTIONS FROM THE RAP AND HRRR SHOWS THAT DESPITE THE MORNING CLOUDS...LOW TO MID LEVEL LAPSE RATES HAVE INCREASED SOME...YIELDING A WEAKLY UNSTABLE ATMOSPHERE ACROSS WESTERN PORTIONS OF THE CWA /CONTINUED CLEARING WILL ALLOW FOR FURTHER DESTABILIZATION/. THE PROJECTED INSTABILITY /UPWARDS TO 1000 J/KG ML CAPE/ COMBINED WITH 0-6KM BULK SHEAR OF 30KTS OR SO WILL PROMOTE THE POSSIBILITY OF STRONG TO LOW END SEVERE STORMS THIS EVENING AND OVERNIGHT. ANOTHER AREA TO WATCH FOR SEVERE STORMS WILL BE ACROSS NORTH CENTRAL NEBRASKA LATE THIS AFTERNOON AS A SECONDARY WARM FRONT LIFTS NORTH TOWARD THE SOUTHEAST SOUTH DAKOTA. ABUNDANT INSTABILITY AND SUFFICIENT SHEAR WOULD PROMOTE RAPID STORM DEVELOPMENT CAPABLE OF LARGE HAIL AND DAMAGING WIND GUSTS. THE HEAVY RAIN THREAT WILL BE NOTICEABLY LESS TONIGHT AS BUFR SOUNDINGS REVEAL A MUCH LESSER INFLUENCE FROM WARM RAIN PROCESSES...BUT WITH PWATS AT OR SLIGHTLY ABOVE AVERAGE...BRIEF HEAVY RAINFALL IS STILL POSSIBLE. THE COLD FRONT CLEARS THE CWA EARLY ON SUNDAY WITH RAIN CHANCES POSSIBLY LINGERING ACROSS OUR FAR EAST THROUGH 15Z...OTHERWISE A SLIGHTLY COOLER AIRMASS IS ANTICIPATED WITH HIGHS RANGING FROM THE MID 70S ACROSS OUR FAR NORTHWEST...TO LOW TO MID 80S SOUTH OF THE INTERSTATE 80 CORRIDOR. WITH MOISTURE LACKING AND A STABLE AIRMASS ANTICIPATED SUNDAY AFTERNOON...STORM CHANCES SHOULD BE KEPT AT BAY UNTIL AT LEAST 00Z MONDAY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 331 PM CDT SAT AUG 23 2014 SUNDAY NIGHT THROUGH TUESDAY...THE MAIN FORECASTING CHALLENGE CONTINUES TO BE PRECIPITATION CHANCES AND THE THREAT FOR HEAVY RAIN AS A TROUGH AND SEMI STATIONARY FRONTAL BOUNDARY PERSISTS ACROSS THE CENTRAL ROCKIES AND PLAINS DURING THE PERIOD. FOR SUNDAY NIGHT...AFTER RELATIVELY QUIET WEATHER CONDS SUNDAY...MID LEVEL WAA WILL INCREASE ALONG THE FRONT RANGE DURING THE EVENING...TRANSITIONING EAST ACROSS THE CENTRAL PLAINS OVERNIGHT SUNDAY NIGHT INTO EARLY MONDAY. AT THE SAME TIME...A NICE H250 JET STREAK WILL LIFT ACROSS NWRN NEBRASKA INTO SOUTH DAKOTA PLACING WESTERN AND NORTH CENTRAL NEBRASKA IN THE RIGHT REAR QUAD OF THIS FEATURE. ENHANCED LIFT ACROSS THE FORECAST AREA...WILL LEAD TO A SHARP INCREASE IN THE THREAT OF PCPN SUNDAY NIGHT INTO MONDAY. IN THE LOWER LEVELS...A FRONTAL BOUNDARY WILL BE ANCHORED ACROSS SRN NEBRASKA SUNDAY NIGHT WITH THE NOSE OF A H85 LOW LEVEL JET POSITIONED ACROSS SWRN NEBRASKA. INHERITED FCST HAD THE HIGHEST POPS ACROSS SRN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT INTO MONDAY MORNING AND APPEARS ON TRACK ATTM. PRECIPITATION CHANCES WILL DECREASE SOMEWHAT MONDAY AS MID LEVEL FORCING PUSHES EAST INTO THE MID MISSOURI VALLEY. BY MONDAY NIGHT...ANOTHER STRONG UPPER LEVEL DISTURBANCE WILL PUSH ACROSS THE CENTRAL PLAINS...LEADING TO INCREASED CHANCES FOR RAIN MONDAY NIGHT...AS WELL AS TUESDAY NIGHT. LOW LEVEL EASTERLY WINDS AND ABUNDANT MID AND UPPER LEVEL MOISTURE TRANSPORT FROM THE SOUTHWEST IN ASSOCIATION WITH HURRICANE MARIE COULD LEAD TO HEAVY RAIN ACROSS THE CENTRAL PLAINS BEGINNING MONDAY NIGHT AND POSSIBLY PERSISTING INTO TUESDAY NIGHT. FURTHER SUPPORT FOR HEAVY RAIN IS EVIDENT IN FCST PWATS RANGING FROM 1.5 TO 2.0 INCHES MONDAY NIGHT THROUGH TUESDAY NIGHT. WEDNESDAY THROUGH SATURDAY...LINGERING PCPN CHANCES ARE THE MAIN FORECAST CHALLENGE IN THE LONG RANGE PERIODS. BY WEDNESDAY INTO THURSDAY...THE PERSISTENT UPPER LEVEL TROUGH ACROSS THE ROCKIES...WILL CROSS THE CENTRAL PLAINS INTO THE MISSISSIPPI VALLEY. THE LATEST GFS SOLN IS 24 HRS FASTER COMPARED TO THE ECMWF IN LIFTING THIS FEATURE EAST OF THE AREA. THE GFS IS DRY AFTER WEDS WITH THE TROUGH OVER MISSOURI VALLEY BY 12Z THURSDAY...WHILE THE ECMWF HAS THIS FEATURE OVER THE SAME AREA BY 12Z FRIDAY. INHERITED FCST WAS DRY WEDS NIGHT AND INTRODUCED POPS FOR THIS PERIOD AS BOTH MODELS HAVE TRENDED SLOWER. WILL HOLD OFF ON INTRODUCING POPS FOR THURSDAY FOR NOW AND WAIT FOR THE MODELS TO COME INTO BETTER AGREEMENT. AFTER UNSEASONABLY COOL HIGHS IN THE 70S FOR WEDNESDAY AND THURSDAY...HIGHS WILL REBOUND BACK INTO THE 80S FOR THURSDAY AND FRIDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1236 PM CDT SAT AUG 23 2014 MVFR OR LOWER STRATUS CONTINUES TO IMPACT MOST AREA TERMINALS EARLY THIS AFTERNOON...BUT THE LATEST NEAR TERM GUIDANCE INDICATES SOME DISSIPATION BACK TO VFR BY MID TO LATE AFTERNOON FOR MOST TERMINALS. THUNDERSTORMS ARE ANTICIPATED OVER MUCH OF THE SANDHILLS REGION THIS EVENING AND OVERNIGHT...FIRST FORMING OVER THE HIGHER TERRAIN OF WESTERN NEBRASKA...THEN SPREADING NORTHEAST OVERNIGHT. BRIEF HEAVY RAINFALL...HAIL AND ERRATIC WIND WOULD ACCOMPANY ANY STORM THAT DEVELOPS. OTHERWISE DRIER AIR TO FOLLOW THE STORMS SHOULD ALLOW FOR WIDESPREAD VFR THROUGH THE REMAINDER OF THE 18Z TAF PERIOD. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CLB SHORT TERM...JACOBS LONG TERM...CLB AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1238 PM CDT SAT AUG 23 2014 .UPDATE... ISSUED AT 532 AM CDT SAT AUG 23 2014 STRATUS IS BEING TO DEVELOP EARLY THIS MORNING AND THE HRRR IS DOING A DECENT JOB WITH THE LOW CLOUD DEPICTION. THE MODEL INDICATES THE MORE WIDESPREAD LOW CLOUD POTENTIAL PRIMARILY ALONG AND NORTH OF THE PLATTE RIVER...BUT CIGS ARE ALSO STARTING TO LOWER FARTHER SOUTH INTO NORTH CENTRAL KANSAS. CONFIDENCE IS NOT HIGH ON THE DEVELOPMENT OF FOG AS WINDS ARE FARILY STEADY FROM THE SOUTHEAST. MODELS SUGGEST THE LOW CLOUDS WILL PERSIST FOR AROUND THREE HOURS OR SO...BREAKING UP BY MID MORNING. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 402 AM CDT SAT AUG 23 2014 EARLY MORNING CONVECTION WAS LIFTING OUT OF OUR CWA ON THE NOSE OF THE LLVL AND AS THE WARM FRONTAL BOUNDARY LIFTS NORTHWARD AHEAD OF AN UPPER LOW EDGING EAST FM IDAHO. SEVERE WEATHER REPORTS FROM THE EVENING CONVECTION WERE LIMITED HOWEVER RAINFALL WAS WIDESPREAD WITH SEVERAL LOCATIONS RECEIVING AMOUNTS NEAR OR ABOVE ONE INCH. WINDS WILL TRANSITION SOUTHERLY AS THE WARM FRONTAL BOUNDARY LIFTS INTO THE DAKOTAS TODAY AND A PERIOD OF BREEZY CONDITIONS ARE FORECAST DURING THE AFTERNOON WITH GUSTS OF 25 TO 30 MPH POSSIBLE...ESPECIALLY FOR OUR SOUTHEASTERN ZONES. AFTERNOON TEMPS ARE LOOKING SIMILAR TO THE LAST FEW DAYS WITH HIGHS RANGING FROM THE UPPER 80S TO THE MID/UPPER 90S...AIDED BY DEEPER MIXING. CANNOT RULE OUT AN ISOLATED TSTM IN THE AFTN IN WAA AHEAD OF THE UPPER TROUGH MOVING INTO MT/WY. UNCERTAINTY EXISTS IN THE CONVECTIVE POTENTIAL TONIGHT AS THE UPPER LOW EDGES INTO THE WESTERN DAKOTAS AND A COLD FRONTAL BOUNDARY ADVANCES EASTWARD FM THE HIGH PLAINS AND REACHES OUR WESTERN CWA PRIOR TO DAYBREAK. WAA AHEAD OF THE FRONT AND CONVERGENCE/DYNAMICS ALONG THE BAROCLINIC ZONE MAY LEAD TO ISOLATED/SCATTERED STORMS. IF STORMS DEVELOP...LACK OF GOOD SHEAR AND MARGINAL INSTABILITY SHOULD LIMIT STORMS FROM BECOMING SEVERE. AS THE COLD FRONT ARRIVES LATE TONIGHT...DRIER AIR ADVECTS SOUTHEAST BEHIND THE BOUNDARY WITH DPS DROPPING OFF TO THE 50S BY SUNDAY MORNING IN OUR WESTERN ZONES. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 402 AM CDT SAT AUG 23 2014 ALOFT: A FAIRLY AMPLIFIED ERN USA RIDGE/WRN USA TROF SUN WILL GRADUALLY DEAMPLIFY NEXT WEEK AND BECOME PROGRESSIVE. A POTENT CLOSED LOW WILL WILL BE EJECTING OUT OF THE TROF...CROSSING THE DAKOTAS SUN. THIS WILL LEAVE A +TILT TROF BEHIND OVER THE WRN USA MON-TUE. THIS TROF WILL ADVANCE INTO THE PLAINS WED AND THE LAST 2-3 RUNS OF THE EC/GFS/GEM/UKMET ARE IN DECENT AGREEMENT THRU THIS TIME FRAME. AGREEMENT BREAKS DOWN THU AND WE SAW HINTS OF THIS 24 HRS AGO. THE GFS KEEPS THE TROF PROGRESSIVE WHILE THE UKMET/EC AND SOME OF THE PAST 4 GEM CYCLES BREAK THE BASE OF THE TROF OFF FROM THE WESTERLIES WHICH BECOME RE-ESTABLISHED OVER SRN CANADA. THE GFS DEVELOPS NW FLOW OVER THE PLAINS WHILE MOST OTHER MODELS HAVE THE TROF AXIS OVERHEAD. SURFACE: A COOL FRONT WILL BE CROSSING THE FCST AREA SUN MORNING. THIS FRONT WILL BECOME STATIONARY ACROSS NRN KS MON AS IT BECOMES PARALLEL WITH THE FLOW ALOFT. THE SRN FRINGE OF CANADIAN HIGH PRES WILL BUILD IN MON-TUE. HOWEVER...WITH THE TROF REMAINING TO THE W THE FRONT WILL BE CONVECTIVELY ACTIVE HAZARDS: MULTIPLE ROUNDS OF TSTMS APPEAR LIKELY WITH MON NIGHT CONTINUING AS THE HIGHEST CONFIDENCE. EXCESSIVE RAINFALL COULD BE A PROBLEM IF THESE TSTM CLUSTERS TRACK OVER SIMILAR AREAS AND WE MAY SEE HYDRO/FLOODING CONCERNS. THE DAILY DETAILS... SUN: WHILE THE BEST LOW-LVL DEWPOINTS WILL BE WHISKED AWAY BY THIS TIME FRAME...THERE IS A NARROW TONGUE OF 10-12C 850 MB DWPTS ALONG THE COOL FRONT. A COUPLE OF SHWRS/TSTMS MAY BE ON-GOING JUST NW OF THE FCST AREA AT DAYBREAK. PRESENT INDICATIONS ARE THAT THEY WILL DISSIPATE. BY AFTERNOON THIS MOIST TONGUE WILL BE OVER THE SE FRINGE OF THE FCST AREA...AND COULD SUPPORT DEVELOPMENT A TSTM OR TWO. SREF MLCAPE 2000-3000 J/KG. DEEP LAYER SHEAR AROUND 25 KTS WILL SUPPORT SEVERE MULTI-CELL CONVECTIVE MODE. SUN NIGHT: A LEE-SIDE LOW WILL BECOME ESTABLISHED NEAR PUB IN THE RIGHT REAR QUADRANT OF AN 80 KT ULJ. THE RESULT WILL BE UPSLOPE FLOW...THE DEVELOPMENT OF A LLJ AND ENHANCED THETA-E ADVECTION. RICH 850 MB DWPTS WILL ADVECT BACK INTO THE REGION LEADING TO DESTABILIZATION AND TSTM DEVELOPMENT OVER THE HIGH PLAINS. SOME OF THIS SHOULD FILTER E INTO THE FCST AREA AFTER MIDNIGHT. MON: LOTS OF UNCERTAINTY ON TEMPS. DEPENDENT ON THE AMT OF CLOUD COVER AND LINGERING TSTM ACTIVITY FROM SUN NIGHT. THIS WILL ACT TO REINFORCE THE FRONT VIA DIFFERENTIAL HEATING. AREAS N OF I-80 COULD STAY IN THE 70S WHILE N-CNTRL KS WILL BAKE INTO THE MID 90S. ANY LEFTOVER TSTM ACTIVITY SHOULD WANE DURING THE DAY. CANT RULE OUT AN ISOLATED LATE DAY TSTM OR TWO. MON NIGHT: THE MODELS CONT TO ADVERTISE MCS DEVELOPMENT AT THE NOSE OF THE LLJ. HIGH POPS ARE IN ORDER ESPECIALLY N OF HWY 6. TUE: PROBABLY A LULL IN TSTM ACTIVITY IN THE WAKE OF THE MCS. AGAIN TEMPS ARE HIGHLY UNCERTAIN. WITH CONVECTIVELY REINFORCED FRONT STILL NEAR THE KS-NEB BORDER...LATE DAY TSTM DEVELOPMENT CANT BE RULED OUT. WED-THU: FOR WHAT IT`S WORTH POTENTIAL EXISTS FOR MORE TSTMS AND IF MCS ACTIVITY IS PLACED JUST RIGHT...MULTIPLE EPISODES COULD RESULT IN EXCESSIVELY HEAVY RAINFALL. THE 18Z/22 GFS ENSEMBLES SHOW ABOVE NORMAL UNCERTAINTY IN TEMPS WED- THU. IF THE EC TURNS OUT CORRECT...WE COULD SEE SUBSTANTIAL CLOUD COVER/STRATUS TRAPPED BENEATH THE FRONT AS THE UPPER TROF MOVES IN. THE GEM/EC/GFS/DGEX ALL INDICATE POTENTIAL FOR 1 OR BOTH DAYS WITH DAYTIME TEMPS JAMMED WAYYYY BELOW NORMAL /AS COOL AS UPPER 60S TO NEAR 70/. FRI: DRY WITH SEASONABLE TEMPS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1235 PM CDT SAT AUG 23 2014 SLOWLY ERODING LOW CLOUDS OUT OF SOUTH CENTRAL NEBRASKA. GRAND ISLAND PRETTY MUCH IN THE CLEAR IT APPEARS...WHILE KEARNEY MAY SKIRT WITH SOME SCATTERED AFTERNOON CLOUDS BUT OVERALL TREND SHOULD BE CLEARING OUT. WINDS WILL CONTINUE TO INCREASE AHEAD OF DEEPENING LOW LEVEL TROUGH WITH GUSTS OVER 20 MPH NOT UNCOMMON. PRECIPITATION WHICH DEVELOPS TO THE WEST TONIGHT COULD MOVE INTO THE AREA LATE IN THE FORECAST...BUT WAS NOT CONFIDENT IN ITS COVERAGE TO ADD TO FORECAST AT THIS TIME. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...FAY SHORT TERM...FAY LONG TERM...HALBLAUB AVIATION...NOAA/NWS/MORITZ
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1236 PM CDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 408 AM CDT SAT AUG 23 2014 A SURFACE ANALYSIS AT 07Z INDICATED A FRONT DRAPED ACROSS SOUTHERN SOUTH DAKOTA WHILE ANOTHER WAS DRAPED FROM WEST CENTRAL INTO NORTHEAST KANSAS. A FAIRLY LARGE MCS WITH EMBEDDED MCVS CONTINUES TO LIFT FROM EASTERN AND NORTHERN NEBRASKA INTO SOUTH DAKOTA. MOST IF NOT ALL SHOWER ACTIVITY HAS ENDED FROM SOUTHWEST NEBRASKA INTO THE CENTRAL SANDHILLS. TEMPERATURES AND DEWPOINTS RANGING IN THE 60S ACROSS WRN AND NCTRL NEBR. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 408 AM CDT SAT AUG 23 2014 FOR TODAY... MODELS ARE IN FAIRLY GOOD AGREEMENT WITH A PV ANOMALY AND MID LEVEL DISTURBANCE LIFTING NORTHEAST FROM SOUTHERN UTAH CURRENTLY AND INTO NORTHEAST COLORADO BY 00Z THIS EVENING. ALONG WITH PEAK HEATING...THIS WILL PROVIDE AN INCREASE TO 30 POPS AFTER 21Z TODAY ACROSS THE NWRN HALF OF FA AND A SLIGHT CHC TO SOUTHEAST AREAS. A FAIRLY CLOUDY MORNING BASED ON RAP MODEL TIME SECTION AND LATEST SATELLITE IMAGERY. AFTERNOON CLEARING TO PARTLY CLOUDY EXPECTED FOR HIGHS FROM LOW 80S NORTHWEST TO UPPER 80S SOUTHWEST. FOR TONIGHT... THE ARW AND NMM MODELS FAVORED WHICH PERFORMED THE BEST WITH CURRENT SYSTEM EXITING THE AREA. BEST OVERALL PRECIPITATION CHANCES THIS EVENING WITH SYSTEM PASSAGE ARE 30-50 POPS WEST OF AN IML-ANW LINE AND 20-30 POPS FOR AREAS EAST. STORM MOTION WILL BE TO THE NORTHEAST AT 15 KTS. MUCH LESS RISK FOR LOCALLY HEAVY RAINFALL AS SOUNDINGS INDICATE WARM RAIN PROCESSES NOT OPERATING. NEVERTHELESS AREAS ACROSS THE WEST THIS EVENING MAY RECEIVE A TENTH TO QUARTER INCH OF NEW RAINFALL. POPS LOWERING TO 20 PERCENT AFTER MIDNIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 408 AM CDT SAT AUG 23 2014 AN ACTIVE WEATHER PATTERN WILL BE IN PLACE THROUGH THIS PERIOD WITH MULTIPLE CHANCES FOR RAIN AND COOLER TEMPERATURES EXPECTED FOR MUCH OF THE WEEK. THE UPPER LEVEL LOW NOW OVER IDAHO WILL CONTINUE TO IMPACT THE FORECAST AREA THROUGH THE FIRST PART OF THIS PERIOD. THE CURRENT FORECAST REMAINS DRY FOR SUNDAY AS THE MODELS SHOW A LACK OF MOISTURE ACROSS THE AREA. SEVERAL MODELS ARE INDICATING A NARROW BAND OF DEVELOPMENT MAINLY ACROSS CENTRAL NEBRASKA ALONG A COLD FRONT THAT LOOKS TO PUSH ACROSS THE FORECAST AREA DURING THE MORNING HOURS. THERE WILL BE SOME MID LEVEL SUPPORT AS THE UPPER LEVEL LOW LIFTS INTO NORTHWEST NORTH DAKOTA...DRAGGING WEAK SHORTWAVE ENERGY ACROSS THE CENTRAL PLAINS. WILL MONITOR FOR ANOTHER FORECAST CYCLE TO SEE IF THIS TREND CONTINUES AND IF SO...MAY NEED TO ADD SOME PRECIPITATION CHANCES FOR PART OF THE DAY SUNDAY. ALSO...A GOOD POOL OF COLD AIR WILL BE CIRCULATING AROUND THE SYSTEM...WITH MUCH COOLER AIR BEING DRAWN DOWN INTO NEBRASKA. BY 00Z TUESDAY THE MODELS ARE LIFTING THE SYSTEM FURTHER NORTH...ALLOWING WARM AIR ADVECTION TO BEGIN ACROSS THE SOUTH AND WESTERN PARTS OF THE AREA. WITH THE COOLER TEMPERATURES AND EXPECTING AT LEAST PARTIAL CLOUD COVER THE FORECAST HIGHS ARE NOW RANGING FROM THE MID 70S TO THE MID 80S. AN UPPER LEVEL LOW NOW MOVING INTO NORTHWEST CANADA OUT OF THE GULF OF ALASKA WILL DIG SOUTH INTO THE NORTHWEST PORTION OF THE CONUS BY MONDAY WHILE THE UPPER LOW TO THE NORTH PUSHES FURTHER NORTH AND EAST AWAY FROM THE AREA. THIS WILL KEEP THE CENTRAL PLAINS UNDER SOUTHWEST FLOW TO HELP BRING MOISTURE UP INTO THE AREA THROUGH MID-WEEK. FOR SUNDAY NIGHT...THE MODELS CONTINUE TO DEVELOP CONVECTION OVER NORTHEAST COLORADO...WHICH THEN SPREADS NORTHEAST INTO WESTERN NEBRASKA. THE AREA WILL BE IN THE FAVORED RIGHT ENTRANCE REGION OF THE JET AND WITH AN INCREASING LOW LEVEL JET /THOUGH NOT PARTICULARLY STRONG/ INTO THE EVENING THERE MIGHT BE ENOUGH FORCING TO KEEP THESE STORMS GOING OVERNIGHT INTO NEBRASKA SO MADE VERY LITTLE CHANGES TO ONGOING PRECIPITATION FORECAST. DURING THE DAY MONDAY...ATTEMPTED TO SHOW A TREND OF THIS ACTIVITY MOVING NORTHEAST AND THROUGH THE FORECAST AREA. MODELS SEEM TO BE SLOWING THE ADVANCEMENT OF THESE STORMS FROM PRIOR MODEL RUNS SO DON/T HAVE A HIGH DEGREE OF CONFIDENCE ON THE TIMING NOR PLACEMENT OF THESE STORM CHANCES. KEPT LIKELY CHANCES FOR RAIN FOR PORTIONS OF THE FORECAST AREA FOR MONDAY NIGHT. STILL LOOKS TO BE A SURFACE LOW SOMEWHERE OVER EASTERN COLORADO/WESTERN KANSAS WITH WARM FRONT EXTENDING INTO CENTRAL AND NORTHEAST NEBRASKA. THE MODELS ARE IN GOOD AGREEMENT WITH A WEAK SHORTWAVE TROUGH MOVING OUT OF THE FOUR CORNERS AND ACROSS THE CENTRAL PLAINS BY 12Z TUESDAY WHILE THE MAIN TROUGH REMAINS OFF TO THE WEST OVER IDAHO AND NEVADA. THE COMBINATION OF FORCING FROM THE SHORTWAVE TROUGH MOVING ACROSS THE AREA AND AN INCREASING LOW LEVEL JET BEING FOCUSED INTO WESTERN NEBRASKA FEEL THAT MONDAY NIGHT HAS THE HIGHEST CHANCES FOR RAINFALL. COULD BE ANOTHER DAY SIMILAR TO YESTERDAY WHERE THERE IS ENOUGH SHEAR AND INSTABILITY TO AT LEAST MENTION A THREAT FOR A FEW SEVERE STORMS...BUT THIS WILL DEPEND ON CONVECTION DURING THE DAY MONDAY AND WITH PRECIPITABLE WATER VALUES OVER 120 PERCENT OF NORMAL AND WARM CLOUD DEPTHS EXCEEDING 3500M STORMS SHOULD BE EFFICIENT RAIN MAKERS SO MAY BE DEALING WITH MORE OF A HEAVY RAIN THREAT. TUESDAY THROUGH FRIDAY...THE LONG RANGE MODELS BEGIN TO DIVERGE WITH HOW THEY HANDLE HOW THE TROUGH TO WEST BEHAVES. THE GFS QUICKLY PUSHES IT EAST THROUGH THE PLAINS AND INTO THE GREAT LAKES REGION BY THURSDAY WHILE THE ECMWF AND GEM ARE SLOWER AND DON/T MOVE IT OUT OF THE CENTRAL PLAINS UNTIL LATER IN THE WEEK. THIS WILL HAVE AN IMPACT ON THE SENSIBLE WEATHER AS THE SLOWER SOLUTION WOULD LINGER PRECIPITATION ACROSS THE AREA LONGER...AT LEAST THROUGH THURSDAY...WHILE THE GFS HAS A DRY FORECAST BY WEDNESDAY MORNING. HAVE NOT JUMPED ON THE SLOWER SOLUTION BUT DID LEAVE SOME SLIGHT CHANCES IN THE FORECAST THROUGH THURSDAY. WHAT IS FAIRLY CERTAIN EITHER WAY IS THAT TEMPERATURES WILL BE COOLER FOR THE WEEK. WITH PRECIPITATION AND CLOUD COVER...SOME DAYS MAY SEE HIGHS STRUGGLE TO GET INTO THE LOW AND MID 70S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1236 PM CDT SAT AUG 23 2014 MVFR OR LOWER STRATUS CONTINUES TO IMPACT MOST AREA TERMINALS EARLY THIS AFTERNOON...BUT THE LATEST NEAR TERM GUIDANCE INDICATES SOME DISSIPATION BACK TO VFR BY MID TO LATE AFTERNOON FOR MOST TERMINALS. THUNDERSTORMS ARE ANTICIPATED OVER MUCH OF THE SANDHILLS REGION THIS EVENING AND OVERNIGHT...FIRST FORMING OVER THE HIGHER TERRAIN OF WESTERN NEBRASKA...THEN SPREADING NORTHEAST OVERNIGHT. BRIEF HEAVY RAINFALL...HAIL AND ERRATIC WIND WOULD ACCOMPANY ANY STORM THAT DEVELOPS. OTHERWISE DRIER AIR TO FOLLOW THE STORMS SHOULD ALLOW FOR WIDESPREAD VFR THROUGH THE REMAINDER OF THE 18Z TAF PERIOD. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...ROBERG SHORT TERM...ROBERG LONG TERM...BROOKS AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
643 AM CDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 408 AM CDT SAT AUG 23 2014 A SURFACE ANALYSIS AT 07Z INDICATED A FRONT DRAPED ACROSS SOUTHERN SOUTH DAKOTA WHILE ANOTHER WAS DRAPED FROM WEST CENTRAL INTO NORTHEAST KANSAS. A FAIRLY LARGE MCS WITH EMBEDDED MCVS CONTINUES TO LIFT FROM EASTERN AND NORTHERN NEBRASKA INTO SOUTH DAKOTA. MOST IF NOT ALL SHOWER ACTIVITY HAS ENDED FROM SOUTHWEST NEBRASKA INTO THE CENTRAL SANDHILLS. TEMPERATURES AND DEWPOINTS RANGING IN THE 60S ACROSS WRN AND NCTRL NEBR. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 408 AM CDT SAT AUG 23 2014 FOR TODAY... MODELS ARE IN FAIRLY GOOD AGREEMENT WITH A PV ANOMALY AND MID LEVEL DISTURBANCE LIFTING NORTHEAST FROM SOUTHERN UTAH CURRENTLY AND INTO NORTHEAST COLORADO BY 00Z THIS EVENING. ALONG WITH PEAK HEATING...THIS WILL PROVIDE AN INCREASE TO 30 POPS AFTER 21Z TODAY ACROSS THE NWRN HALF OF FA AND A SLIGHT CHC TO SOUTHEAST AREAS. A FAIRLY CLOUDY MORNING BASED ON RAP MODEL TIME SECTION AND LATEST SATELLITE IMAGERY. AFTERNOON CLEARING TO PARTLY CLOUDY EXPECTED FOR HIGHS FROM LOW 80S NORTHWEST TO UPPER 80S SOUTHWEST. FOR TONIGHT... THE ARW AND NMM MODELS FAVORED WHICH PERFORMED THE BEST WITH CURRENT SYSTEM EXITING THE AREA. BEST OVERALL PRECIPITATION CHANCES THIS EVENING WITH SYSTEM PASSAGE ARE 30-50 POPS WEST OF AN IML-ANW LINE AND 20-30 POPS FOR AREAS EAST. STORM MOTION WILL BE TO THE NORTHEAST AT 15 KTS. MUCH LESS RISK FOR LOCALLY HEAVY RAINFALL AS SOUNDINGS INDICATE WARM RAIN PROCESSES NOT OPERATING. NEVERTHELESS AREAS ACROSS THE WEST THIS EVENING MAY RECEIVE A TENTH TO QUARTER INCH OF NEW RAINFALL. POPS LOWERING TO 20 PERCENT AFTER MIDNIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 408 AM CDT SAT AUG 23 2014 AN ACTIVE WEATHER PATTERN WILL BE IN PLACE THROUGH THIS PERIOD WITH MULTIPLE CHANCES FOR RAIN AND COOLER TEMPERATURES EXPECTED FOR MUCH OF THE WEEK. THE UPPER LEVEL LOW NOW OVER IDAHO WILL CONTINUE TO IMPACT THE FORECAST AREA THROUGH THE FIRST PART OF THIS PERIOD. THE CURRENT FORECAST REMAINS DRY FOR SUNDAY AS THE MODELS SHOW A LACK OF MOISTURE ACROSS THE AREA. SEVERAL MODELS ARE INDICATING A NARROW BAND OF DEVELOPMENT MAINLY ACROSS CENTRAL NEBRASKA ALONG A COLD FRONT THAT LOOKS TO PUSH ACROSS THE FORECAST AREA DURING THE MORNING HOURS. THERE WILL BE SOME MID LEVEL SUPPORT AS THE UPPER LEVEL LOW LIFTS INTO NORTHWEST NORTH DAKOTA...DRAGGING WEAK SHORTWAVE ENERGY ACROSS THE CENTRAL PLAINS. WILL MONITOR FOR ANOTHER FORECAST CYCLE TO SEE IF THIS TREND CONTINUES AND IF SO...MAY NEED TO ADD SOME PRECIPITATION CHANCES FOR PART OF THE DAY SUNDAY. ALSO...A GOOD POOL OF COLD AIR WILL BE CIRCULATING AROUND THE SYSTEM...WITH MUCH COOLER AIR BEING DRAWN DOWN INTO NEBRASKA. BY 00Z TUESDAY THE MODELS ARE LIFTING THE SYSTEM FURTHER NORTH...ALLOWING WARM AIR ADVECTION TO BEGIN ACROSS THE SOUTH AND WESTERN PARTS OF THE AREA. WITH THE COOLER TEMPERATURES AND EXPECTING AT LEAST PARTIAL CLOUD COVER THE FORECAST HIGHS ARE NOW RANGING FROM THE MID 70S TO THE MID 80S. AN UPPER LEVEL LOW NOW MOVING INTO NORTHWEST CANADA OUT OF THE GULF OF ALASKA WILL DIG SOUTH INTO THE NORTHWEST PORTION OF THE CONUS BY MONDAY WHILE THE UPPER LOW TO THE NORTH PUSHES FURTHER NORTH AND EAST AWAY FROM THE AREA. THIS WILL KEEP THE CENTRAL PLAINS UNDER SOUTHWEST FLOW TO HELP BRING MOISTURE UP INTO THE AREA THROUGH MID-WEEK. FOR SUNDAY NIGHT...THE MODELS CONTINUE TO DEVELOP CONVECTION OVER NORTHEAST COLORADO...WHICH THEN SPREADS NORTHEAST INTO WESTERN NEBRASKA. THE AREA WILL BE IN THE FAVORED RIGHT ENTRANCE REGION OF THE JET AND WITH AN INCREASING LOW LEVEL JET /THOUGH NOT PARTICULARLY STRONG/ INTO THE EVENING THERE MIGHT BE ENOUGH FORCING TO KEEP THESE STORMS GOING OVERNIGHT INTO NEBRASKA SO MADE VERY LITTLE CHANGES TO ONGOING PRECIPITATION FORECAST. DURING THE DAY MONDAY...ATTEMPTED TO SHOW A TREND OF THIS ACTIVITY MOVING NORTHEAST AND THROUGH THE FORECAST AREA. MODELS SEEM TO BE SLOWING THE ADVANCEMENT OF THESE STORMS FROM PRIOR MODEL RUNS SO DON/T HAVE A HIGH DEGREE OF CONFIDENCE ON THE TIMING NOR PLACEMENT OF THESE STORM CHANCES. KEPT LIKELY CHANCES FOR RAIN FOR PORTIONS OF THE FORECAST AREA FOR MONDAY NIGHT. STILL LOOKS TO BE A SURFACE LOW SOMEWHERE OVER EASTERN COLORADO/WESTERN KANSAS WITH WARM FRONT EXTENDING INTO CENTRAL AND NORTHEAST NEBRASKA. THE MODELS ARE IN GOOD AGREEMENT WITH A WEAK SHORTWAVE TROUGH MOVING OUT OF THE FOUR CORNERS AND ACROSS THE CENTRAL PLAINS BY 12Z TUESDAY WHILE THE MAIN TROUGH REMAINS OFF TO THE WEST OVER IDAHO AND NEVADA. THE COMBINATION OF FORCING FROM THE SHORTWAVE TROUGH MOVING ACROSS THE AREA AND AN INCREASING LOW LEVEL JET BEING FOCUSED INTO WESTERN NEBRASKA FEEL THAT MONDAY NIGHT HAS THE HIGHEST CHANCES FOR RAINFALL. COULD BE ANOTHER DAY SIMILAR TO YESTERDAY WHERE THERE IS ENOUGH SHEAR AND INSTABILITY TO AT LEAST MENTION A THREAT FOR A FEW SEVERE STORMS...BUT THIS WILL DEPEND ON CONVECTION DURING THE DAY MONDAY AND WITH PRECIPITABLE WATER VALUES OVER 120 PERCENT OF NORMAL AND WARM CLOUD DEPTHS EXCEEDING 3500M STORMS SHOULD BE EFFICIENT RAIN MAKERS SO MAY BE DEALING WITH MORE OF A HEAVY RAIN THREAT. TUESDAY THROUGH FRIDAY...THE LONG RANGE MODELS BEGIN TO DIVERGE WITH HOW THEY HANDLE HOW THE TROUGH TO WEST BEHAVES. THE GFS QUICKLY PUSHES IT EAST THROUGH THE PLAINS AND INTO THE GREAT LAKES REGION BY THURSDAY WHILE THE ECMWF AND GEM ARE SLOWER AND DON/T MOVE IT OUT OF THE CENTRAL PLAINS UNTIL LATER IN THE WEEK. THIS WILL HAVE AN IMPACT ON THE SENSIBLE WEATHER AS THE SLOWER SOLUTION WOULD LINGER PRECIPITATION ACROSS THE AREA LONGER...AT LEAST THROUGH THURSDAY...WHILE THE GFS HAS A DRY FORECAST BY WEDNESDAY MORNING. HAVE NOT JUMPED ON THE SLOWER SOLUTION BUT DID LEAVE SOME SLIGHT CHANCES IN THE FORECAST THROUGH THURSDAY. WHAT IS FAIRLY CERTAIN EITHER WAY IS THAT TEMPERATURES WILL BE COOLER FOR THE WEEK. WITH PRECIPITATION AND CLOUD COVER...SOME DAYS MAY SEE HIGHS STRUGGLE TO GET INTO THE LOW AND MID 70S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 642 AM CDT SAT AUG 23 2014 NEAR TERM AVIATION CONCERN IS DURATION OF MVFR CIGS. POTENTIAL FOR CIGS BKN015-BKN020 FOR BOTH KLBF AND KVTN TERMINALS UNTIL 16Z. THEREAFTER...ANY CIGS SHOULD LIFT TO VFR AND PERSIST FOR REMAINDER OF THE PERIOD. DID NOT INCLUDE MENTION OF SHRA OR TSRA. EXPECT MAIN AREA OF DEVELOPMENT TO BE WEST OF THE TERMINALS AFTER 00Z/24TH. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...ROBERG SHORT TERM...ROBERG LONG TERM...BROOKS AVIATION...ROBERG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
537 AM CDT SAT AUG 23 2014 .UPDATE... ISSUED AT 532 AM CDT SAT AUG 23 2014 STRATUS IS BEING TO DEVELOP EARLY THIS MORNING AND THE HRRR IS DOING A DECENT JOB WITH THE LOW CLOUD DEPICTION. THE MODEL INDICATES THE MORE WIDESPREAD LOW CLOUD POTENTIAL PRIMARILY ALONG AND NORTH OF THE PLATTE RIVER...BUT CIGS ARE ALSO STARTING TO LOWER FARTHER SOUTH INTO NORTH CENTRAL KANSAS. CONFIDENCE IS NOT HIGH ON THE DEVELOPMENT OF FOG AS WINDS ARE FARILY STEADY FROM THE SOUTHEAST. MODELS SUGGEST THE LOW CLOUDS WILL PERSIST FOR AROUND THREE HOURS OR SO...BREAKING UP BY MID MORNING. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 402 AM CDT SAT AUG 23 2014 EARLY MORNING CONVECTION WAS LIFTING OUT OF OUR CWA ON THE NOSE OF THE LLVL AND AS THE WARM FRONTAL BOUNDARY LIFTS NORTHWARD AHEAD OF AN UPPER LOW EDGING EAST FM IDAHO. SEVERE WEATHER REPORTS FROM THE EVENING CONVECTION WERE LIMITED HOWEVER RAINFALL WAS WIDESPREAD WITH SEVERAL LOCATIONS RECEIVING AMOUNTS NEAR OR ABOVE ONE INCH. WINDS WILL TRANSITION SOUTHERLY AS THE WARM FRONTAL BOUNDARY LIFTS INTO THE DAKOTAS TODAY AND A PERIOD OF BREEZY CONDITIONS ARE FORECAST DURING THE AFTERNOON WITH GUSTS OF 25 TO 30 MPH POSSIBLE...ESPECIALLY FOR OUR SOUTHEASTERN ZONES. AFTERNOON TEMPS ARE LOOKING SIMILAR TO THE LAST FEW DAYS WITH HIGHS RANGING FROM THE UPPER 80S TO THE MID/UPPER 90S...AIDED BY DEEPER MIXING. CANNOT RULE OUT AN ISOLATED TSTM IN THE AFTN IN WAA AHEAD OF THE UPPER TROUGH MOVING INTO MT/WY. UNCERTAINTY EXISTS IN THE CONVECTIVE POTENTIAL TONIGHT AS THE UPPER LOW EDGES INTO THE WESTERN DAKOTAS AND A COLD FRONTAL BOUNDARY ADVANCES EASTWARD FM THE HIGH PLAINS AND REACHES OUR WESTERN CWA PRIOR TO DAYBREAK. WAA AHEAD OF THE FRONT AND CONVERGENCE/DYNAMICS ALONG THE BAROCLINIC ZONE MAY LEAD TO ISOLATED/SCATTERED STORMS. IF STORMS DEVELOP...LACK OF GOOD SHEAR AND MARGINAL INSTABILITY SHOULD LIMIT STORMS FROM BECOMING SEVERE. AS THE COLD FRONT ARRIVES LATE TONIGHT...DRIER AIR ADVECTS SOUTHEAST BEHIND THE BOUNDARY WITH DPS DROPPING OFF TO THE 50S BY SUNDAY MORNING IN OUR WESTERN ZONES. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 402 AM CDT SAT AUG 23 2014 ALOFT: A FAIRLY AMPLIFIED ERN USA RIDGE/WRN USA TROF SUN WILL GRADUALLY DEAMPLIFY NEXT WEEK AND BECOME PROGRESSIVE. A POTENT CLOSED LOW WILL WILL BE EJECTING OUT OF THE TROF...CROSSING THE DAKOTAS SUN. THIS WILL LEAVE A +TILT TROF BEHIND OVER THE WRN USA MON-TUE. THIS TROF WILL ADVANCE INTO THE PLAINS WED AND THE LAST 2-3 RUNS OF THE EC/GFS/GEM/UKMET ARE IN DECENT AGREEMENT THRU THIS TIME FRAME. AGREEMENT BREAKS DOWN THU AND WE SAW HINTS OF THIS 24 HRS AGO. THE GFS KEEPS THE TROF PROGRESSIVE WHILE THE UKMET/EC AND SOME OF THE PAST 4 GEM CYCLES BREAK THE BASE OF THE TROF OFF FROM THE WESTERLIES WHICH BECOME RE-ESTABLISHED OVER SRN CANADA. THE GFS DEVELOPS NW FLOW OVER THE PLAINS WHILE MOST OTHER MODELS HAVE THE TROF AXIS OVERHEAD. SURFACE: A COOL FRONT WILL BE CROSSING THE FCST AREA SUN MORNING. THIS FRONT WILL BECOME STATIONARY ACROSS NRN KS MON AS IT BECOMES PARALLEL WITH THE FLOW ALOFT. THE SRN FRINGE OF CANADIAN HIGH PRES WILL BUILD IN MON-TUE. HOWEVER...WITH THE TROF REMAINING TO THE W THE FRONT WILL BE CONVECTIVELY ACTIVE HAZARDS: MULTIPLE ROUNDS OF TSTMS APPEAR LIKELY WITH MON NIGHT CONTINUING AS THE HIGHEST CONFIDENCE. EXCESSIVE RAINFALL COULD BE A PROBLEM IF THESE TSTM CLUSTERS TRACK OVER SIMILAR AREAS AND WE MAY SEE HYDRO/FLOODING CONCERNS. THE DAILY DETAILS... SUN: WHILE THE BEST LOW-LVL DEWPOINTS WILL BE WHISKED AWAY BY THIS TIME FRAME...THERE IS A NARROW TONGUE OF 10-12C 850 MB DWPTS ALONG THE COOL FRONT. A COUPLE OF SHWRS/TSTMS MAY BE ON-GOING JUST NW OF THE FCST AREA AT DAYBREAK. PRESENT INDICATIONS ARE THAT THEY WILL DISSIPATE. BY AFTERNOON THIS MOIST TONGUE WILL BE OVER THE SE FRINGE OF THE FCST AREA...AND COULD SUPPORT DEVELOPMENT A TSTM OR TWO. SREF MLCAPE 2000-3000 J/KG. DEEP LAYER SHEAR AROUND 25 KTS WILL SUPPORT SEVERE MULTI-CELL CONVECTIVE MODE. SUN NIGHT: A LEE-SIDE LOW WILL BECOME ESTABLISHED NEAR PUB IN THE RIGHT REAR QUADRANT OF AN 80 KT ULJ. THE RESULT WILL BE UPSLOPE FLOW...THE DEVELOPMENT OF A LLJ AND ENHANCED THETA-E ADVECTION. RICH 850 MB DWPTS WILL ADVECT BACK INTO THE REGION LEADING TO DESTABILIZATION AND TSTM DEVELOPMENT OVER THE HIGH PLAINS. SOME OF THIS SHOULD FILTER E INTO THE FCST AREA AFTER MIDNIGHT. MON: LOTS OF UNCERTAINTY ON TEMPS. DEPENDENT ON THE AMT OF CLOUD COVER AND LINGERING TSTM ACTIVITY FROM SUN NIGHT. THIS WILL ACT TO REINFORCE THE FRONT VIA DIFFERENTIAL HEATING. AREAS N OF I-80 COULD STAY IN THE 70S WHILE N-CNTRL KS WILL BAKE INTO THE MID 90S. ANY LEFTOVER TSTM ACTIVITY SHOULD WANE DURING THE DAY. CANT RULE OUT AN ISOLATED LATE DAY TSTM OR TWO. MON NIGHT: THE MODELS CONT TO ADVERTISE MCS DEVELOPMENT AT THE NOSE OF THE LLJ. HIGH POPS ARE IN ORDER ESPECIALLY N OF HWY 6. TUE: PROBABLY A LULL IN TSTM ACTIVITY IN THE WAKE OF THE MCS. AGAIN TEMPS ARE HIGHLY UNCERTAIN. WITH CONVECTIVELY REINFORCED FRONT STILL NEAR THE KS-NEB BORDER...LATE DAY TSTM DEVELOPMENT CANT BE RULED OUT. WED-THU: FOR WHAT IT`S WORTH POTENTIAL EXISTS FOR MORE TSTMS AND IF MCS ACTIVITY IS PLACED JUST RIGHT...MULTIPLE EPISODES COULD RESULT IN EXCESSIVELY HEAVY RAINFALL. THE 18Z/22 GFS ENSEMBLES SHOW ABOVE NORMAL UNCERTAINTY IN TEMPS WED- THU. IF THE EC TURNS OUT CORRECT...WE COULD SEE SUBSTANTIAL CLOUD COVER/STRATUS TRAPPED BENEATH THE FRONT AS THE UPPER TROF MOVES IN. THE GEM/EC/GFS/DGEX ALL INDICATE POTENTIAL FOR 1 OR BOTH DAYS WITH DAYTIME TEMPS JAMMED WAYYYY BELOW NORMAL /AS COOL AS UPPER 60S TO NEAR 70/. FRI: DRY WITH SEASONABLE TEMPS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 512 AM CDT SAT AUG 23 2014 CONVECTION HAS DEPARTED THE TERMINALS AND FOR THE MOST PART DRY WEATHER IS FORECAST. THERE IS AN OUTSIDE CHANCE FOR A STORM OR TWO DURING THE AFTERNOON AND TONIGHT AHEAD OF AN APPROACHING COLD FRONT AND UPPER LEVEL TROUGH BUT CHANCES ARE NOT GREAT ENOUGH TO INCLUDE MENTION IN THE TAFS. THERE MAY BE A BRIEF VSBY RESTRICTION AROUND DAYBREAK THIS MORNING...BUT VSBYS HAVE BEEN SLOW TO DROP. OTHERWISE...LOOK FOR SOUTHERLY WINDS TO BE ON THE INCREASE WITH WIND GUSTS AROUND 25KTS POSSIBLE DURING THE AFTERNOON. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...FAY SHORT TERM...FAY LONG TERM...HALBLAUB AVIATION...FAY
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
409 AM CDT SAT AUG 23 2014 .SYNOPSIS... ISSUED AT 408 AM CDT SAT AUG 23 2014 A SURFACE ANALYSIS AT 07Z INDICATED A FRONT DRAPED ACROSS SOUTHERN SOUTH DAKOTA WHILE ANOTHER WAS DRAPED FROM WEST CENTRAL INTO NORTHEAST KANSAS. A FAIRLY LARGE MCS WITH EMBEDDED MCVS CONTINUES TO LIFT FROM EASTERN AND NORTHERN NEBRASKA INTO SOUTH DAKOTA. MOST IF NOT ALL SHOWER ACTIVITY HAS ENDED FROM SOUTHWEST NEBRASKA INTO THE CENTRAL SANDHILLS. TEMPERATURES AND DEWPOINTS RANGING IN THE 60S ACROSS WRN AND NCTRL NEBR. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 408 AM CDT SAT AUG 23 2014 FOR TODAY... MODELS ARE IN FAIRLY GOOD AGREEMENT WITH A PV ANOMALY AND MID LEVEL DISTURBANCE LIFTING NORTHEAST FROM SOUTHERN UTAH CURRENTLY AND INTO NORTHEAST COLORADO BY 00Z THIS EVENING. ALONG WITH PEAK HEATING...THIS WILL PROVIDE AN INCREASE TO 30 POPS AFTER 21Z TODAY ACROSS THE NWRN HALF OF FA AND A SLIGHT CHC TO SOUTHEAST AREAS. A FAIRLY CLOUDY MORNING BASED ON RAP MODEL TIME SECTION AND LATEST SATELLITE IMAGERY. AFTERNOON CLEARING TO PARTLY CLOUDY EXPECTED FOR HIGHS FROM LOW 80S NORTHWEST TO UPPER 80S SOUTHWEST. FOR TONIGHT... THE ARW AND NMM MODELS FAVORED WHICH PERFORMED THE BEST WITH CURRENT SYSTEM EXITING THE AREA. BEST OVERALL PRECIPITATION CHANCES THIS EVENING WITH SYSTEM PASSAGE ARE 30-50 POPS WEST OF AN IML-ANW LINE AND 20-30 POPS FOR AREAS EAST. STORM MOTION WILL BE TO THE NORTHEAST AT 15 KTS. MUCH LESS RISK FOR LOCALLY HEAVY RAINFALL AS SOUNDINGS INDICATE WARM RAIN PROCESSES NOT OPERATING. NEVERTHELESS AREAS ACROSS THE WEST THIS EVENING MAY RECEIVE A TENTH TO QUARTER INCH OF NEW RAINFALL. POPS LOWERING TO 20 PERCENT AFTER MIDNIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 408 AM CDT SAT AUG 23 2014 AN ACTIVE WEATHER PATTERN WILL BE IN PLACE THROUGH THIS PERIOD WITH MULTIPLE CHANCES FOR RAIN AND COOLER TEMPERATURES EXPECTED FOR MUCH OF THE WEEK. THE UPPER LEVEL LOW NOW OVER IDAHO WILL CONTINUE TO IMPACT THE FORECAST AREA THROUGH THE FIRST PART OF THIS PERIOD. THE CURRENT FORECAST REMAINS DRY FOR SUNDAY AS THE MODELS SHOW A LACK OF MOISTURE ACROSS THE AREA. SEVERAL MODELS ARE INDICATING A NARROW BAND OF DEVELOPMENT MAINLY ACROSS CENTRAL NEBRASKA ALONG A COLD FRONT THAT LOOKS TO PUSH ACROSS THE FORECAST AREA DURING THE MORNING HOURS. THERE WILL BE SOME MID LEVEL SUPPORT AS THE UPPER LEVEL LOW LIFTS INTO NORTHWEST NORTH DAKOTA...DRAGGING WEAK SHORTWAVE ENERGY ACROSS THE CENTRAL PLAINS. WILL MONITOR FOR ANOTHER FORECAST CYCLE TO SEE IF THIS TREND CONTINUES AND IF SO...MAY NEED TO ADD SOME PRECIPITATION CHANCES FOR PART OF THE DAY SUNDAY. ALSO...A GOOD POOL OF COLD AIR WILL BE CIRCULATING AROUND THE SYSTEM...WITH MUCH COOLER AIR BEING DRAWN DOWN INTO NEBRASKA. BY 00Z TUESDAY THE MODELS ARE LIFTING THE SYSTEM FURTHER NORTH...ALLOWING WARM AIR ADVECTION TO BEGIN ACROSS THE SOUTH AND WESTERN PARTS OF THE AREA. WITH THE COOLER TEMPERATURES AND EXPECTING AT LEAST PARTIAL CLOUD COVER THE FORECAST HIGHS ARE NOW RANGING FROM THE MID 70S TO THE MID 80S. AN UPPER LEVEL LOW NOW MOVING INTO NORTHWEST CANADA OUT OF THE GULF OF ALASKA WILL DIG SOUTH INTO THE NORTHWEST PORTION OF THE CONUS BY MONDAY WHILE THE UPPER LOW TO THE NORTH PUSHES FURTHER NORTH AND EAST AWAY FROM THE AREA. THIS WILL KEEP THE CENTRAL PLAINS UNDER SOUTHWEST FLOW TO HELP BRING MOISTURE UP INTO THE AREA THROUGH MID-WEEK. FOR SUNDAY NIGHT...THE MODELS CONTINUE TO DEVELOP CONVECTION OVER NORTHEAST COLORADO...WHICH THEN SPREADS NORTHEAST INTO WESTERN NEBRASKA. THE AREA WILL BE IN THE FAVORED RIGHT ENTRANCE REGION OF THE JET AND WITH AN INCREASING LOW LEVEL JET /THOUGH NOT PARTICULARLY STRONG/ INTO THE EVENING THERE MIGHT BE ENOUGH FORCING TO KEEP THESE STORMS GOING OVERNIGHT INTO NEBRASKA SO MADE VERY LITTLE CHANGES TO ONGOING PRECIPITATION FORECAST. DURING THE DAY MONDAY...ATTEMPTED TO SHOW A TREND OF THIS ACTIVITY MOVING NORTHEAST AND THROUGH THE FORECAST AREA. MODELS SEEM TO BE SLOWING THE ADVANCEMENT OF THESE STORMS FROM PRIOR MODEL RUNS SO DON/T HAVE A HIGH DEGREE OF CONFIDENCE ON THE TIMING NOR PLACEMENT OF THESE STORM CHANCES. KEPT LIKELY CHANCES FOR RAIN FOR PORTIONS OF THE FORECAST AREA FOR MONDAY NIGHT. STILL LOOKS TO BE A SURFACE LOW SOMEWHERE OVER EASTERN COLORADO/WESTERN KANSAS WITH WARM FRONT EXTENDING INTO CENTRAL AND NORTHEAST NEBRASKA. THE MODELS ARE IN GOOD AGREEMENT WITH A WEAK SHORTWAVE TROUGH MOVING OUT OF THE FOUR CORNERS AND ACROSS THE CENTRAL PLAINS BY 12Z TUESDAY WHILE THE MAIN TROUGH REMAINS OFF TO THE WEST OVER IDAHO AND NEVADA. THE COMBINATION OF FORCING FROM THE SHORTWAVE TROUGH MOVING ACROSS THE AREA AND AN INCREASING LOW LEVEL JET BEING FOCUSED INTO WESTERN NEBRASKA FEEL THAT MONDAY NIGHT HAS THE HIGHEST CHANCES FOR RAINFALL. COULD BE ANOTHER DAY SIMILAR TO YESTERDAY WHERE THERE IS ENOUGH SHEAR AND INSTABILITY TO AT LEAST MENTION A THREAT FOR A FEW SEVERE STORMS...BUT THIS WILL DEPEND ON CONVECTION DURING THE DAY MONDAY AND WITH PRECIPITABLE WATER VALUES OVER 120 PERCENT OF NORMAL AND WARM CLOUD DEPTHS EXCEEDING 3500M STORMS SHOULD BE EFFICIENT RAIN MAKERS SO MAY BE DEALING WITH MORE OF A HEAVY RAIN THREAT. TUESDAY THROUGH FRIDAY...THE LONG RANGE MODELS BEGIN TO DIVERGE WITH HOW THEY HANDLE HOW THE TROUGH TO WEST BEHAVES. THE GFS QUICKLY PUSHES IT EAST THROUGH THE PLAINS AND INTO THE GREAT LAKES REGION BY THURSDAY WHILE THE ECMWF AND GEM ARE SLOWER AND DON/T MOVE IT OUT OF THE CENTRAL PLAINS UNTIL LATER IN THE WEEK. THIS WILL HAVE AN IMPACT ON THE SENSIBLE WEATHER AS THE SLOWER SOLUTION WOULD LINGER PRECIPITATION ACROSS THE AREA LONGER...AT LEAST THROUGH THURSDAY...WHILE THE GFS HAS A DRY FORECAST BY WEDNESDAY MORNING. HAVE NOT JUMPED ON THE SLOWER SOLUTION BUT DID LEAVE SOME SLIGHT CHANCES IN THE FORECAST THROUGH THURSDAY. WHAT IS FAIRLY CERTAIN EITHER WAY IS THAT TEMPERATURES WILL BE COOLER FOR THE WEEK. WITH PRECIPITATION AND CLOUD COVER...SOME DAYS MAY SEE HIGHS STRUGGLE TO GET INTO THE LOW AND MID 70S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1142 PM CDT FRI AUG 22 2014 TSTMS WILL CONTINUE LIFTING NORTH OVERNIGHT AND EXIT NRN NEB AROUND 12Z. A PERIOD OF MVFR CIGS MAY DEVELOP IN THE WAKE OF THESE STORMS BUT THE LATEST INDICATIONS ARE THESE CIGS WOULD NOT LAST MORE THAN AN HOUR OR TWO BEFORE IMPROVING TO VFR. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...ROBERG SHORT TERM...ROBERG LONG TERM...BROOKS AVIATION...CDC
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1226 AM CDT SAT AUG 23 2014 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 256 PM CDT FRI AUG 22 2014 THE HIGHLIGHT OF THE SHORT TERM PERIOD WILL BE THE FACT WE ARE EXPECTING THUNDERSTORMS TODAY/TONIGHT. THERE STILL REMAINS SOME UNCERTAINTY FOR TIMING...LOCATION...AND OVERALL DEVELOPMENT. THE WARM FRONT TO OUR SOUTH...WHICH IS SITUATED OVER THE KANSAS/NEBRASKA BORDER...IS JUST MOSEYING ALONG TODAY AND HAS CAUSED SOME CONCERN FOR DEVELOPMENT. SHOWERS/STORMS SHOULD DEVELOP ALONG THIS BOUNDARY AS THE CAP BEGINS TO BREAK. SPC MESOSCALE ANALYSIS PAGE HAS US CAPPED UNTIL ABOUT 22-23Z. AT THIS TIME WE SHOULD SEE THE BEGINNING STAGES FOR INITIATION ALONG THE BOUNDARY TO OUR SOUTH. AMPLE INSTABILITY OF ABOUT 2000-3000 J/KG WILL BE IN PLACE...DUE TO A VERY MOIST BOUNDARY LAYER AND STEEP LAPSE RATES. MOST UNSTABLE CAPE COULD BE AS HIGH AS 4000 J/KG. BULK SHEAR 0-6 KM WILL BE AROUND 30 KNOTS...AND THIS IS NOT TOO IMPRESSIVE...HOWEVER...LOW LEVEL SHEAR WILL BE STRONG. EARLIER RUNS OF THE RAP INDICATED HELICITY VALUES NEAR 400 M2/S2 WOULD BE IN PLACE AROUND 23Z FOR WESTERN PORTIONS OF THE CWA. THESE VALUES WILL PUSH EASTWARD THROUGH THE AFTERNOON/EVENING. THESE LOW LEVEL HELICITY VALUES COUPLED WITH AMPLE INSTABILITY WILL POSE A THREAT FOR SOME ISOLATED TORNADOES...MAINLY FOR OUR NEBRASKA COUNTIES. WITH THAT BEING...WIND AND HAIL WILL BE THE MAIN THREATS TODAY/TONIGHT. THE BEST CHANCE FOR SEVERE WEATHER WILL BE ACROSS OUR NEBRASKA COUNTIES...BUT THE ENTIRE CWA DOES HAVE THE POTENTIAL FOR SEVERE WEATHER. I DO EXPECT THUNDERSTORM ACTIVITY TO KICK INTO GEAR AROUND 6 OR 7 PM...IF NOT SOONER. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 256 PM CDT FRI AUG 22 2014 VARIOUS RAIN CHANCES FOR THE WEEKEND AND IN TO THE FIRST PART OF THE WORK WEEK...ALONG WITH FLUCTUATING TEMPERATURES ARE PRIMARY FORECAST CONCERNS. WILL KEEP THIS FAIRLY SHORT DUE TO POSSIBLE SEVERE WEATHER DEVELOPING LATER THIS AFTERNOON. STARTING OUT SATURDAY EVENING IN THE MID/UPPER LEVELS...THERE SHOULD BE A LARGE AMPLITUDE TROUGH OVER THE ROCKIES WITH A CLOSED LOW SITUATED OVER EAST CENTRAL MONTANA...AS THE CURRENT SYSTEM OVER THE PACIFIC NW DRIFTS EASTWARD. THIS WILL PUSH THE RIDGE A LITTLE EAST AS WELL WITH THE AXIS STRETCHING FROM LAKE SUPERIOR TO MISSISSIPPI. THE BETTER FORCING WITH THE LOW PRESSURE SHOULD BE TO THE WEST AND NORTH OF OUR REGION. AT THE SURFACE...EXPECT A FRONTAL BOUNDARY TO BE TO OUR NORTH ACROSS SDAK AT 00Z AND THEN THIS WILL PUSH INTO OUR AREA BY SUNDAY MORNING. HAS NOT TAKEN A WHOLE LOT TO SET OFF CONVECTION THE PAST WEEK AND WHILE THE SET UP FOR SATURDAY NIGHT IS NOT AS GOOD AS TONIGHT...WILL PROBABLY STILL NEED SOME LOW POPS GIVEN APPROACHING WEAK COLD FRONT AND ANTICIPATED LOW LEVEL JET. PREVIOUS SHIFT AFD NOTED SOME HEAT BURST POTENTIAL WITH ANY THUNDERSTORMS THAT DO DEVELOP AND THIS SCENARIO STILL IN PLACE. WEATHER SHOULD BE QUIET DURING THE DAYTIME ON SUNDAY BEHIND THE COLD FRONT AND POSSIBLE SUNDAY NIGHT ALTHOUGH BOTH THE NAM AND GFS ARE DEVELOPING SOME PRECIPITATION TO THE WEST AND MOVING ACROSS THE CWA SUNDAY NIGHT. GFS APPEARS TO OVERDEVELOP A VORTICITY MAX ALTHOUGH DIFFICULT TO TOTALLY DISCOUNT WITH CYCLONIC FLOW IN UPPER LEVELS. MONDAY NIGHT AND TUESDAY NIGHT STILL LOOK ACTIVE AS YET ANOTHER HIGH AMPLITUDE TROUGH IS SLATED TO MOVE ACROSS THE ROCKIES AND INTO THE PLAINS. AT THE SURFACE AN EAST/WEST STATIONARY FRONT WILL HANG OUT OVER THE AREA RESULTING IN THE CLASSIC NIGHTTIME RAIN EVENTS. BY WEDNESDAY THE EXTENDED MODELS IN DECENT AGREEMENT IN PUSHING THE TROUGH EAST THROUGH THE CWA WITH RIDING THEN MOVING IN TO QUIET THINGS DOWN FOR THE REMAINDER OF THE WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1206 AM CDT SAT AUG 23 2014 SHOWERS AND THUNDERSTORMS WILL LINGER AT THE TERMINALS FOR ANOTHER HOUR OR SO THEN CONDITIONS WILL DRY OUT BY DAYBREAK. THERE MAY BE A BRIEF PERIOD OF REDUCED VSBYS IN BR DUE TO THE WET GROUND...BUT CONFIDENCE IS NOT HIGH FOR DEVELOPMENT OF FOG. LOOK FOR WINDS TO TRANSITION SOUTHERLY DURING THE DAY WITH WIND SPEEDS INCREASING AS THE SFC GRADIENT TIGHTENS. WIND GUSTS AROUND 25KTS ARE POSSIBLE. THERE IS AN OUTSIDE CHC FOR A TSTM BUT CHCS ARE NOT GREAT ENOUGH TO INCLUDE JUST YET. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...GUERRERO LONG TERM...EWALD AVIATION...FAY
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1028 PM EDT SUN AUG 24 2014 .SYNOPSIS... HIGH PRESSURE WILL EXPAND SOUTH ACROSS THE AREA TONIGHT AND WEDNESDAY...BRINGING COOL AND DRY WEATHER. TROPICAL STORM CRISTOBAL MAY BECOME A HURRICANE IN THE NEXT FEW DAYS AS IT PASSES SEVERAL HUNDRED MILES EAST OF THE CAROLINAS. A WARMING TREND WILL DEVELOP LATE IN THE WEEK. A BACKDOOR FRONT MAY APPROACH BY NEXT WEEKEND...BRINGING A RISK FOR SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM SUNDAY...ASIDE FROM A FEW PATCHES OF STRATOCUMULUS NEAR THE BEACHES SKIES ARE CLEAR AND SHOULD REMAIN MOSTLY CLEAR OVERNIGHT. THE 00Z MHX SOUNDING SHOWED A CLEAR SUBSIDENCE INVERSION AT 5300 FEET AGL AND MATCHED 18Z MODEL PROJECTIONS CLOSELY. THE ONLY CHANGE WITH THIS UPDATE WAS TO LOWER DEWPOINT FORECASTS BY A FEW DEGREES THROUGH THE NIGHT BASED ON CURRENT OBS AND THE 00Z MHX SOUNDING. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... AN EXTENSIVE STRATOCUMULUS DECK INLAND IS BEGINNING TO DECAY NOW THAT THE SUN IS SETTING. SKIES SHOULD BECOME GENERALLY CLEAR OVERNIGHT AS DRIER AIR ARRIVES IN THE 850 MB LAYER NEAR THE TOP OF TODAY`S SURFACE MIXED LAYER. BESIDES DOWNWARD ADJUSTMENTS TO SKY COVER...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE FORECAST. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS... COOL BUT BEAUTIFUL LATE SUMMER AFTERNOON COMING TO AN END...LEAVING WHAT WILL BE ONE OF THE COOLER NIGHTS THIS AREA HAS SEEN IN QUITE SOME TIME. COLD FRONT CONTINUES TO SAG WELL SOUTH OF THE AREA...AND HAS PUSHED TO NEARLY THE FLORIDA STATE LINE TODAY. DRIVING THIS BOUNDARY IS A STRONG RIDGE OF HIGH PRESSURE OF CANADIAN ORIGIN...WITH THE CENTER OF THIS HIGH ACTUALLY WELL NORTH OF WINNIPEG, CANADA IN THE NORTH CENTRAL PART OF THE COUNTRY. THIS HIGH IS RIDGING INTO NEW ENGLAND AND THEN DOWN THE EASTERN SEABOARD...WITH ABNORMALLY COOL AND DRY AIR FOR LATE AUGUST FILTERING INTO THE REGION. THIS AIR MASS IS VERY FALL-LIKE...AND DEWPOINTS HAVE FALLEN INTO THE LOW AND MID 60S AREA-WIDE TODAY. THIS DRY AIR HAS LIMITED TOTAL INSTABILITY...AND ALTHOUGH HIGH-RES GUIDANCE CONTINUES TO SUGGEST THE POTENTIAL FOR ISOLATED SEA-BREEZE SHOWERS THROUGH THIS EVE...THE CHANCE FOR THAT IS WANING...AND EVEN DIURNAL CU IS HAVING TROUBLE GAINING MUCH AGITATION. STILL CONTINUED JUST VERY SCHC ALONG THE SC PORTION OF THE SEA BREEZE FOR THE NEXT FEW HOURS. IF A SHOWER DOES DEVELOP IT WILL ERODE QUICKLY AFTER DARK...AS WILL THE MAJORITY OF THE CLOUD COVER. NE WINDS WILL REMAIN ELEVATED TONIGHT...LIKELY STAYING 5-10 MPH INTO MONDAY MORNING. THESE WINDS WILL CONTINUE TO ADVECT COOL/DRY AIR...THUS DRIVING MINS WELL BELOW 70...WITH LOWER 60S ENCOMPASSING THE NORTHERN HALF OR 2/3 OF THE CWA. WHILE ELEVATED WINDS TEND TO LIMIT OVERALL COOLING...NE WINDS HAVE A TENDENCY TO COOL THE AREA MORE THAN WOULD TYPICALLY BE EXPECTED...ESPECIALLY ACROSS THE CAPE FEAR REGION. FOR THIS REASON HAVE FORECAST THE LOWEST TEMPS IN THE NE ZONES TONIGHT...AND WILMINGTON MAY SEE ITS COOLEST NIGHT SINCE EARLY JUNE. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 PM SUNDAY...THE FORECAST AREA WILL REMAIN IN THE GRIP OF AN UNSEASONABLE NE FLOW AS HIGH PRESSURE CENTERED ACROSS THE NORTHEAST U.S. RIDGES SOUTH...WITH ITS AXIS REMAINING TO THE WEST OF OUR FORECAST AREA. AT THE SAME TIME...SLOW STRENGTHENING OF THE VERY SLOW MOVING TROPICAL STORM ACROSS THE BAHAMAS IS EXPECTED. THIS WILL SERVE TO PROLONG THE RATHER TIGHT PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS. AS THESE NE WINDS PERSIST...THEY WILL SERVE TO PILE UP WATER ON THE IMMEDIATE COAST. THIS IN COMBINATION WITH THE NEW MOON WILL INCREASE THE RISK FOR MINOR BEACH EROSION FOR THOSE BEACHES EXPOSED TO A NE FETCH AND MINOR COASTAL FLOODING DURING THE NIGHTTIME HIGH TIDE... BOTH AT THE BEACHES AND ALONG THE LOWER CAPE FEAR RIVER. OTHER HAZARDS WILL INCLUDE A STRONG LONG SHORE CURRENT...MODERATE TO PERHAPS STRONG RIP CURRENTS AND HIGHER THAN NORMAL...ROUGH SURF. TEMPS WILL BE COOL IN THIS BREEZY NE FLOW REGIME. HIGHS WILL BE IN THE LOWER TO MID 80S...WITH TUE PERHAPS SLIGHTLY COOLER THAN MON. LOWS WILL BE IN THE LOWER TO MID 60S WITH PERHAPS UPPER 60S AT THE BEACHES. WIND SPEEDS ON MON WILL BE UP TO 10 TO 20 MPH WITH HIGHER GUSTS...ESPECIALLY AT THE BEACHES. OFFSHORE SHOWERS ARE EXPECTED TO REMAIN THERE FOR MUCH OF THE PERIOD. TRAJECTORIES WILL AT TIMES BRING THE SHOWERS VERY NEAR THE BEACHES...BUT GIVEN THE DRYNESS OF THE COLUMN...EXPECT THESE SHOWERS TO LARGELY ERODE BEFORE MOVING ONSHORE. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 300 PM SUNDAY...THE MID LEVEL PATTERN WILL SHOW TYPICAL LATE SUMMER LETHARGY THROUGH THE PERIOD AS RIDGING WILL BE THE CENTRAL THEME. THE AXIS OF THE RIDGE MOVES FROM THE MISSISSIPPI VALLEY TO OFF THE PENINSULA OF FLORIDA BY THE END OF THE PERIOD. AT THE SURFACE...WEAK HIGH PRESSURE WILL PREVAIL AS WELL AND AS THE MID LEVEL RIDGE REPOSITIONS...A RELATIVELY WEAK BACKDOOR FRONT WILL MOVE ACROSS FRIDAY. THIS WILL SERVE TO ENHANCE THE POPS BOTH FRIDAY AND SATURDAY. HOWEVER MOISTURE AND FORCING REMAIN RELATIVELY WEAK AND SLIGHT CHANCE FRIDAY TO LOW CHANCE SATURDAY WILL SUFFICE FOR NOW. THERE IS ALSO SLIGHT CHANCE POPS FOR WEDNESDAY AND THURSDAY ALONG THE COASTAL AREAS. THE COOL REFRESHING AIRMASS WILL BE A THING OF THE PAST AS TEMPERATURES WEDNESDAY THROUGH FRIDAY WILL BE AT OR JUST ABOVE CLIMATOLOGY. FOR NEXT WEEKEND...A SLIGHT DROP IN TEMPERATURES IS SEEN AS THE BACKDOOR FRONT MOVES ACROSS BUT JUST A COUPLE OF DEGREES. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... AS OF 00Z...VFR CONDITIONS ARE EXPECTED THROUGH THE VALID PERIOD. CLOUD COVER TODAY HAS BEEN LIMITED TO SCT/BKN 3-6KFT SHALLOW CU TRAPPED BENEATH AN INVERSION. AS HIGH PRESSURE WEDGES INTO THE CAROLINAS FROM THE NORTHEAST...DRIER AIR WILL CONTINUE MOVING INTO OUR AREA TONIGHT THROUGH MON. NORTHEAST WINDS AOB 10 KT TONIGHT WILL ELIMINATE ANY CHANCE OF VSBY ISSUES. MVFR STRATOCU COULD GRAZE THE COASTAL TERMS OVERNIGHT...BUT I AM FAIRLY CONFIDENT THAT ANY PERSISTENT MVFR CIGS WILL REMAIN OFFSHORE. VFR WILL PERSIST INTO MON AS NORTHEAST WINDS INCREASE TO 10-15 KT WITH GUSTS OF 20 KT DURING THE DAY. EXTENDED OUTLOOK...VFR WILL PREVAIL THROUGH THE EXTENDED PERIOD. SLIGHT CHANCE OF SHOWERS ACROSS OUR NORTHERN ZONES FRI. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM SUNDAY...LATEST OBS MATCH OBSERVATIONS VERY CLOSELY. THE 00Z MHX SOUNDING SHOWED 25 KNOTS THROUGHOUT THE RESIDUAL MIXED LAYER FROM EARLIER TODAY MATCHING MODEL PROJECTIONS CLOSELY. NO CHANGES ARE NEEDED TO THE FORECAST. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... WIND SPEEDS ARE RUNNING JUST A BIT HIGHER THAN FORECAST NEARSHORE BUT LOOK GOOD OFFSHORE COMPARED TO BUOYS 41037 AND 41004. MARINE MOS GUIDANCE AND LATEST RUC AND HRRR MODELS SUGGEST WIND SPEEDS WILL BACK MORE NORTHERLY OVERNIGHT BUT WILL NOT DECREASE MUCH IN SPEED. IN FACT THE ADVECTION OF COOLER AIR OVER THE VERY WARM OCEAN SURFACE LATER TONIGHT WILL PROBABLY ENHANCE GUSTINESS AND DOWNWARD TRANSPORT OF STRONGER WINDS FROM ALOFT. NO SIGNIFICANT CHANGES WERE MADE TO THE FORECAST OVERNIGHT. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS... PINCHING NE GRADIENT EAST OF A RIDGE OF HIGH PRESSURE EXPANDING DOWN THE COAST IS CAUSING DETERIORATING MARINE CONDITIONS TODAY. WINDS ARE SLOWLY BUT STEADILY RISING OUT OF THE NE...WITH SPEEDS OF 15-20 KTS COMMON ACROSS THE WATERS...WITH SOME GUSTS APPROACHING 30 KTS DEVELOPING OVER THE NORTHERN WATERS AND OUTSIDE OF 20 NM. AS THE HIGH PRESSURE STRENGTHENS TONIGHT...THE GRADIENT WILL TIGHTEN FURTHER...AIDED BY THE DISTANT BUT STRENGTHENING TROPICAL STORM CRISTOBAL NEAR THE BAHAMAS. THIS WILL CAUSE WIDESPREAD 15-25 KT NE WINDS THROUGH THE PERIOD...WITH SEAS BUILDING TO 5-8 FT. WAVE HEIGHTS WILL BE DRIVEN ALMOST ENTIRELY BY A NE WIND CHOP TONIGHT. HOWEVER...LONGER PERIOD SWELL ASSOCIATED WITH TROPICAL STORM CRISTOBAL IS FORECAST TO BEGIN TO ENTER THE SPECTRUM TONIGHT. ONLY NOTICEABLE LONG-SWELL PRESENTLY EXISTS AT 41004 /EDISTO BUOY/ WHICH IS OBSERVING A LOW-AMPLITUDE 13 SEC SWELL. EXPECT THIS TO GRADUALLY LIFT NE INTO THE LOCAL WATERS...BUT HAVE ONLY MINIMAL CONTRIBUTION TO THE SIGNIFICANT SEAS UNTIL MONDAY. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 PM SUNDAY...THE PRESSURE DIFFERENCE BETWEEN HIGH PRESSURE TO THE NORTH AND A SLOWLY DEVELOPING TROPICAL STORM ACROSS THE BAHAMAS WILL KEEP A TIGHT PRESSURE GRADIENT ACROSS THE WATERS. A SMALL CRAFT ADVISORY REMAINS IN EFFECT. WINDS WILL COMMONLY BE SUSTAINED AT 20 TO 25 KT. THE LONG NE FETCH WILL KEEP SEAS IN THE 4 TO 7 FT RANGE WITH AT LEAST 8 FT SEAS BEYOND 20 NM. A 10 TO 12 SECOND SE SWELL IS EXPECTED TO SLOWLY BUILD THROUGH THE PERIOD. LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 300 PM SUNDAY...CONFIDENCE CONTINUES TO BUILD THAT THE ONLY IMPACTS FROM CRISTOBAL WILL BE THE SWELL COMPONENT ADDED TO THE WAVE SPECTRUM. THE LATEST WAVEWATCH HURRICANE BULLETIN FOR FRYING PAN SHOALS SHOWS 7-8 FEET DEVELOPING OR PERSISTING WEDNESDAY THROUGH EARLY THURSDAY WITH A GOOD PORTION OF THIS BEING THE WIND WAVE COMPONENT. THIS MAKES SENSE AS THE GFS IS NOT DEVELOPING THE SYSTEM APPRECIABLY. FOR THE 0-20 MILE COASTAL WATERS 4-6 FEET WEDNESDAY AND EARLY THURSDAY SHOULD SUFFICE. BY FRIDAY A WEAK PRESSURE PATTERN YIELDS LIGHT WINDS AND SEAS. FOR THE WINDS WEDNESDAY AND THURSDAY...A NORTHEASTERLY FLOW OF 10-15 KNOTS WEDNESDAY DROPS TO SINGLE DIGITS THURSDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...COASTAL FLOOD ADVISORY FROM 6 PM TO 9 PM EDT THIS EVENING FOR NCZ106-108. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT TUESDAY FOR AMZ250-252-254-256. && $$ NEAR TERM...JDW/TRA SHORT TERM...RJD LONG TERM...SHK AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
724 PM EDT SUN AUG 24 2014 .SYNOPSIS... HIGH PRESSURE WILL EXPAND SOUTH ACROSS THE AREA TONIGHT AND WEDNESDAY...BRINGING COOL AND DRY WEATHER. TROPICAL STORM CRISTOBAL MAY BECOME A HURRICANE IN THE NEXT FEW DAYS AS IT PASSES SEVERAL HUNDRED MILES EAST OF THE CAROLINAS. A WARMING TREND WILL DEVELOP LATE IN THE WEEK. A BACKDOOR FRONT MAY APPROACH BY NEXT WEEKEND...BRINGING A RISK FOR SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 730 PM SUNDAY...AN EXTENSIVE STRATOCUMULUS DECK INLAND IS BEGINNING TO DECAY NOW THAT THE SUN IS SETTING. SKIES SHOULD BECOME GENERALLY CLEAR OVERNIGHT AS DRIER AIR ARRIVES IN THE 850 MB LAYER NEAR THE TOP OF TODAY`S SURFACE MIXED LAYER. BESIDES DOWNWARD ADJUSTMENTS TO SKY COVER...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE FORECAST. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS... COOL BUT BEAUTIFUL LATE SUMMER AFTERNOON COMING TO AN END...LEAVING WHAT WILL BE ONE OF THE COOLER NIGHTS THIS AREA HAS SEEN IN QUITE SOME TIME. COLD FRONT CONTINUES TO SAG WELL SOUTH OF THE AREA...AND HAS PUSHED TO NEARLY THE FLORIDA STATE LINE TODAY. DRIVING THIS BOUNDARY IS A STRONG RIDGE OF HIGH PRESSURE OF CANADIAN ORIGIN...WITH THE CENTER OF THIS HIGH ACTUALLY WELL NORTH OF WINNIPEG, CANADA IN THE NORTH CENTRAL PART OF THE COUNTRY. THIS HIGH IS RIDGING INTO NEW ENGLAND AND THEN DOWN THE EASTERN SEABOARD...WITH ABNORMALLY COOL AND DRY AIR FOR LATE AUGUST FILTERING INTO THE REGION. THIS AIR MASS IS VERY FALL-LIKE...AND DEWPOINTS HAVE FALLEN INTO THE LOW AND MID 60S AREA-WIDE TODAY. THIS DRY AIR HAS LIMITED TOTAL INSTABILITY...AND ALTHOUGH HIGH-RES GUIDANCE CONTINUES TO SUGGEST THE POTENTIAL FOR ISOLATED SEA-BREEZE SHOWERS THROUGH THIS EVE...THE CHANCE FOR THAT IS WANING...AND EVEN DIURNAL CU IS HAVING TROUBLE GAINING MUCH AGITATION. STILL CONTINUED JUST VERY SCHC ALONG THE SC PORTION OF THE SEA BREEZE FOR THE NEXT FEW HOURS. IF A SHOWER DOES DEVELOP IT WILL ERODE QUICKLY AFTER DARK...AS WILL THE MAJORITY OF THE CLOUD COVER. NE WINDS WILL REMAIN ELEVATED TONIGHT...LIKELY STAYING 5-10 MPH INTO MONDAY MORNING. THESE WINDS WILL CONTINUE TO ADVECT COOL/DRY AIR...THUS DRIVING MINS WELL BELOW 70...WITH LOWER 60S ENCOMPASSING THE NORTHERN HALF OR 2/3 OF THE CWA. WHILE ELEVATED WINDS TEND TO LIMIT OVERALL COOLING...NE WINDS HAVE A TENDENCY TO COOL THE AREA MORE THAN WOULD TYPICALLY BE EXPECTED...ESPECIALLY ACROSS THE CAPE FEAR REGION. FOR THIS REASON HAVE FORECAST THE LOWEST TEMPS IN THE NE ZONES TONIGHT...AND WILMINGTON MAY SEE ITS COOLEST NIGHT SINCE EARLY JUNE. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 PM SUNDAY...THE FORECAST AREA WILL REMAIN IN THE GRIP OF AN UNSEASONABLE NE FLOW AS HIGH PRESSURE CENTERED ACROSS THE NORTHEAST U.S. RIDGES SOUTH...WITH ITS AXIS REMAINING TO THE WEST OF OUR FORECAST AREA. AT THE SAME TIME...SLOW STRENGTHENING OF THE VERY SLOW MOVING TROPICAL STORM ACROSS THE BAHAMAS IS EXPECTED. THIS WILL SERVE TO PROLONG THE RATHER TIGHT PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS. AS THESE NE WINDS PERSIST...THEY WILL SERVE TO PILE UP WATER ON THE IMMEDIATE COAST. THIS IN COMBINATION WITH THE NEW MOON WILL INCREASE THE RISK FOR MINOR BEACH EROSION FOR THOSE BEACHES EXPOSED TO A NE FETCH AND MINOR COASTAL FLOODING DURING THE NIGHTTIME HIGH TIDE... BOTH AT THE BEACHES AND ALONG THE LOWER CAPE FEAR RIVER. OTHER HAZARDS WILL INCLUDE A STRONG LONG SHORE CURRENT...MODERATE TO PERHAPS STRONG RIP CURRENTS AND HIGHER THAN NORMAL...ROUGH SURF. TEMPS WILL BE COOL IN THIS BREEZY NE FLOW REGIME. HIGHS WILL BE IN THE LOWER TO MID 80S...WITH TUE PERHAPS SLIGHTLY COOLER THAN MON. LOWS WILL BE IN THE LOWER TO MID 60S WITH PERHAPS UPPER 60S AT THE BEACHES. WIND SPEEDS ON MON WILL BE UP TO 10 TO 20 MPH WITH HIGHER GUSTS...ESPECIALLY AT THE BEACHES. OFFSHORE SHOWERS ARE EXPECTED TO REMAIN THERE FOR MUCH OF THE PERIOD. TRAJECTORIES WILL AT TIMES BRING THE SHOWERS VERY NEAR THE BEACHES...BUT GIVEN THE DRYNESS OF THE COLUMN...EXPECT THESE SHOWERS TO LARGELY ERODE BEFORE MOVING ONSHORE. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 300 PM SUNDAY...THE MID LEVEL PATTERN WILL SHOW TYPICAL LATE SUMMER LETHARGY THROUGH THE PERIOD AS RIDGING WILL BE THE CENTRAL THEME. THE AXIS OF THE RIDGE MOVES FROM THE MISSISSIPPI VALLEY TO OFF THE PENINSULA OF FLORIDA BY THE END OF THE PERIOD. AT THE SURFACE...WEAK HIGH PRESSURE WILL PREVAIL AS WELL AND AS THE MID LEVEL RIDGE REPOSITIONS...A RELATIVELY WEAK BACKDOOR FRONT WILL MOVE ACROSS FRIDAY. THIS WILL SERVE TO ENHANCE THE POPS BOTH FRIDAY AND SATURDAY. HOWEVER MOISTURE AND FORCING REMAIN RELATIVELY WEAK AND SLIGHT CHANCE FRIDAY TO LOW CHANCE SATURDAY WILL SUFFICE FOR NOW. THERE IS ALSO SLIGHT CHANCE POPS FOR WEDNESDAY AND THURSDAY ALONG THE COASTAL AREAS. THE COOL REFRESHING AIRMASS WILL BE A THING OF THE PAST AS TEMPERATURES WEDNESDAY THROUGH FRIDAY WILL BE AT OR JUST ABOVE CLIMATOLOGY. FOR NEXT WEEKEND...A SLIGHT DROP IN TEMPERATURES IS SEEN AS THE BACKDOOR FRONT MOVES ACROSS BUT JUST A COUPLE OF DEGREES. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... AS OF 00Z...VFR CONDITIONS ARE EXPECTED THROUGH THE VALID PERIOD. CLOUD COVER TODAY HAS BEEN LIMITED TO SCT/BKN 3-6KFT SHALLOW CU TRAPPED BENEATH AN INVERSION. AS HIGH PRESSURE WEDGES INTO THE CAROLINAS FROM THE NORTHEAST...DRIER AIR WILL CONTINUE MOVING INTO OUR AREA TONIGHT THROUGH MON. NORTHEAST WINDS AOB 10 KT TONIGHT WILL ELIMINATE ANY CHANCE OF VSBY ISSUES. MVFR STRATOCU COULD GRAZE THE COASTAL TERMS OVERNIGHT...BUT I AM FAIRLY CONFIDENT THAT ANY PERSISTENT MVFR CIGS WILL REMAIN OFFSHORE. VFR WILL PERSIST INTO MON AS NORTHEAST WINDS INCREASE TO 10-15 KT WITH GUSTS OF 20 KT DURING THE DAY. EXTENDED OUTLOOK...VFR WILL PREVAIL THROUGH THE EXTENDED PERIOD. SLIGHT CHANCE OF SHOWERS ACROSS OUR NORTHERN ZONES FRI. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 730 PM SUNDAY...WIND SPEEDS ARE RUNNING JUST A BIT HIGHER THAN FORECAST NEARSHORE BUT LOOK GOOD OFFSHORE COMPARED TO BUOYS 41037 AND 41004. MARINE MOS GUIDANCE AND LATEST RUC AND HRRR MODELS SUGGEST WIND SPEEDS WILL BACK MORE NORTHERLY OVERNIGHT BUT WILL NOT DECREASE MUCH IN SPEED. IN FACT THE ADVECTION OF COOLER AIR OVER THE VERY WARM OCEAN SURFACE LATER TONIGHT WILL PROBABLY ENHANCE GUSTINESS AND DOWNWARD TRANSPORT OF STRONGER WINDS FROM ALOFT. NO SIGNIFICANT CHANGES WERE MADE TO THE FORECAST OVERNIGHT. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS... PINCHING NE GRADIENT EAST OF A RIDGE OF HIGH PRESSURE EXPANDING DOWN THE COAST IS CAUSING DETERIORATING MARINE CONDITIONS TODAY. WINDS ARE SLOWLY BUT STEADILY RISING OUT OF THE NE...WITH SPEEDS OF 15-20 KTS COMMON ACROSS THE WATERS...WITH SOME GUSTS APPROACHING 30 KTS DEVELOPING OVER THE NORTHERN WATERS AND OUTSIDE OF 20 NM. AS THE HIGH PRESSURE STRENGTHENS TONIGHT...THE GRADIENT WILL TIGHTEN FURTHER...AIDED BY THE DISTANT BUT STRENGTHENING TROPICAL STORM CRISTOBAL NEAR THE BAHAMAS. THIS WILL CAUSE WIDESPREAD 15-25 KT NE WINDS THROUGH THE PERIOD...WITH SEAS BUILDING TO 5-8 FT. WAVE HEIGHTS WILL BE DRIVEN ALMOST ENTIRELY BY A NE WIND CHOP TONIGHT. HOWEVER...LONGER PERIOD SWELL ASSOCIATED WITH TROPICAL STORM CRISTOBAL IS FORECAST TO BEGIN TO ENTER THE SPECTRUM TONIGHT. ONLY NOTICEABLE LONG-SWELL PRESENTLY EXISTS AT 41004 /EDISTO BUOY/ WHICH IS OBSERVING A LOW-AMPLITUDE 13 SEC SWELL. EXPECT THIS TO GRADUALLY LIFT NE INTO THE LOCAL WATERS...BUT HAVE ONLY MINIMAL CONTRIBUTION TO THE SIGNIFICANT SEAS UNTIL MONDAY. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 PM SUNDAY...THE PRESSURE DIFFERENCE BETWEEN HIGH PRESSURE TO THE NORTH AND A SLOWLY DEVELOPING TROPICAL STORM ACROSS THE BAHAMAS WILL KEEP A TIGHT PRESSURE GRADIENT ACROSS THE WATERS. A SMALL CRAFT ADVISORY REMAINS IN EFFECT. WINDS WILL COMMONLY BE SUSTAINED AT 20 TO 25 KT. THE LONG NE FETCH WILL KEEP SEAS IN THE 4 TO 7 FT RANGE WITH AT LEAST 8 FT SEAS BEYOND 20 NM. A 10 TO 12 SECOND SE SWELL IS EXPECTED TO SLOWLY BUILD THROUGH THE PERIOD. LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 300 PM SUNDAY...CONFIDENCE CONTINUES TO BUILD THAT THE ONLY IMPACTS FROM CRISTOBAL WILL BE THE SWELL COMPONENT ADDED TO THE WAVE SPECTRUM. THE LATEST WAVEWATCH HURRICANE BULLETIN FOR FRYING PAN SHOALS SHOWS 7-8 FEET DEVELOPING OR PERSISTING WEDNESDAY THROUGH EARLY THURSDAY WITH A GOOD PORTION OF THIS BEING THE WIND WAVE COMPONENT. THIS MAKES SENSE AS THE GFS IS NOT DEVELOPING THE SYSTEM APPRECIABLY. FOR THE 0-20 MILE COASTAL WATERS 4-6 FEET WEDNESDAY AND EARLY THURSDAY SHOULD SUFFICE. BY FRIDAY A WEAK PRESSURE PATTERN YIELDS LIGHT WINDS AND SEAS. FOR THE WINDS WEDNESDAY AND THURSDAY...A NORTHEASTERLY FLOW OF 10-15 KNOTS WEDNESDAY DROPS TO SINGLE DIGITS THURSDAY. && .TIDES/COASTAL FLOODING... AS OF 300 PM SUNDAY...RIDGE OF HIGH PRESSURE EXPANDING DOWN THE COAST IS DRIVING A PINCHED GRADIENT...AND FORCING A LONG PERIOD OF GUSTY NE WINDS LOCALLY. THESE WINDS ARE FORCING WATER TO "PILE UP" NEAR THE COASTLINE...AS NOTED BY TIDAL ANOMALIES OF 1 TO 2 FEET AT THE LOCAL BEACHES. THIS FORCING COMBINED WITH ASTRONOMICAL HIGH TIDES DUE TO THE APPROACH OF THE NEW MOON (NEW MOON IS MONDAY)...WILL CAUSE HIGH TIDE LEVELS THIS EVENING TO APPROACH OR SLIGHTLY EXCEED MINOR FLOOD THRESHOLDS ON THE EAST FACING BEACHES NORTH OF CAPE FEAR. HIGH TIDE IS AROUND 730 PM AT WRIGHTSVILLE BEACH...AND A COASTAL FLOOD ADVISORY HAS BEEN ISSUED...VALID FROM 6PM TO 9PM. THE EAST FACING BEACHES OF SC WILL FARE SLIGHTLY BETTER DUE TO THE COASTLINE ORIENTATION WITH RESPECT TO WIND DIRECTION...AND THUS SHOULD STAY BELOW MINOR FLOOD THRESHOLDS TONIGHT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...COASTAL FLOOD ADVISORY FROM 6 PM TO 9 PM EDT THIS EVENING FOR NCZ106-108. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT TUESDAY FOR AMZ250-252-254-256. && $$ NEAR TERM...JDW/TRA SHORT TERM...RJD LONG TERM...SHK AVIATION...BJR TIDES/COASTAL FLOODING...JDW
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
351 PM EDT SAT AUG 23 2014 .SYNOPSIS... A COLD FRONT TO OUR SOUTH WILL BE MOVING AWAY FROM THE AREA BY SUNDAY MORNING. PROGRESSIVELY DRIER AND COOLER AIR WILL BE PUSHING SOUTH IN THE WAKE OF THE FRONT AND THIS WILL ALLOW FOR FAR FEWER SHOWERS AND THUNDERSTORMS SUNDAY. HIGH PRESSURE WILL EXPAND SOUTH ACROSS THE AREA NEXT WEEK WITH ITS INFLUENCE BEGINNING TO WANE DURING THE MIDDLE AND LATER PORTIONS OF NEXT WEEK. WE WILL BE MONITORING FOR THE DEVELOPMENT OF TROPICAL CYCLONE CRISTOBAL IN THE COMING DAYS. CRISTOBAL MAY MAKE ITS CLOSEST APPROACH TO THE CAROLINA COAST MID OR LATE NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... AS OF 300 PM SATURDAY...SHOWERS AND THUNDERSTORMS BEGINNING TO BECOME MORE WIDESPREAD ACROSS THE AREA...IN A TREND THAT WILL LIKELY CONTINUE INTO TONIGHT. THE CWA IS BISECTED THIS AFTERNOON BY A COLD FRONT...WHICH IS ALIGNED ROUGHLY FROM MYRTLE BEACH...TO FLORENCE...AND UP TOWARDS CHARLOTTE. THIS BOUNDARY AT THE SURFACE IS DIFFICULT TO IDENTIFY DUE TO THE LIGHT GRADIENT SURROUNDING IT KEEPING WINDS LIGHT...BUT WINDS NORTH OF THE BOUNDARY ARE PRIMARILY FROM THE NORTH...WITH VARIABLE DIRECTIONS TO THE SOUTH. ALOFT...FRONT IS MORE EASILY IDENTIFIABLE ON PW IMAGERY...AS MUCH DRIER AIR IS FILTERING IN BEHIND THE FRONT. IT IS INTERESTING TO NOTE...HOWEVER...THAT CONVECTION IS BECOMING WIDESPREAD IN THE DRIER COLUMN NORTH OF THE BOUNDARY. ALTHOUGH THIS SEEMS TO BE COUNTER-INTUITIVE...THE BLENDED/LAYERED PWAT PRODUCT FROM CIRA SHOWS THE DRY AIR CONFINED TO THE LAYER ABOVE 700MB...WHILE MOISTURE IS ACTUALLY INCREASING BELOW 850MB. THIS WILL CONTINUE TO BE THE CASE THROUGH TONIGHT AS EVIDENCED BY BOTH RUC AND NAM FORECAST PROFILES SHOWING PWATS INCREASING TO WELL ABOVE 2 INCHES THIS EVENING AND TONIGHT...BEFORE DRYING OCCURS LATE. TRYING TO DETERMINE WHERE CONVECTION WILL BE MOST WIDESPREAD TODAY IS TRICKY...BUT HIGH RES ARW/NAM/HRRR ALL SUGGEST THE BEST FOCUS WILL BE ACROSS NC COUNTIES THROUGH THE EVE...WITH LESSER CHANCES IN SC. THIS IS LIKELY DUE TO A SHORTWAVE WHICH IS PROGGED TO DROP ACROSS THE AREA...DIRECTED ON NW FLOW BETWEEN A TROUGH OVER NEW ENGLAND A RIDGE ACROSS THE MS VLY. AS THIS IMPULSE MOVES OVERHEAD...IT WILL TAP INTO AN ENVIRONMENT CHARACTERIZED BY STRONG THETA-E RIDGING AND MLCAPE OVER 2000 J/KG. HAVE ATTEMPTED TO TIME THE HIGHEST POP TO CORRELATE WITH DEEPEST FORECAST-SOUNDING SATURATION AND THE HIGH RES GUIDANCE...BUT AT LEAST SCT CONVECTION WILL LIKELY BE ONGOING FOR A MANY-HOUR PERIOD...CENTERED AROUND 7PM. THIS SUGGESTS THAT SHOWERS WILL PERSIST SEVERAL HOURS AFTER NIGHTFALL THANKS TO THE FORCING ALOFT...AND HAVE POP WANING AFTER MIDNIGHT. WHILE SEVERE IS NOT ANTICIPATED...ESPECIALLY WITH THE DRYING OCCURRING ALOFT AND SOME CONFLUENCE WITHIN THE EXIT REGION OF AN UPPER JET MOVING NEARBY...ISOLATED GUSTY WINDS ARE POSSIBLE AS IS TYPICAL WITH NW FLOW EVENTS. HEAVY RAINFALL WILL BE THE PRIMARY THREAT THROUGH THE PERIOD HOWEVER. THE FRONT WILL FINALLY GET KICKED SOUTH TONIGHT...AND SHOULD CLEAR THE CWA BY DAYBREAK SUNDAY. A DEVELOPING NE SURGE BEHIND THE BOUNDARY WILL HELP DRIVE THIS FRONT SOUTH...BUT ANY COOL ADVECTION WILL BE A BIT LATE TO SIGNIFICANTLY AFFECT MINS TONIGHT. HAVE SIDED CLOSELY WITH THE MET NUMBERS WHICH HAVE PERFORMED QUITE WELL THE PAST FEW NIGHTS...AND LOWS WILL DROP TO AROUND 70 IN THE FAR NORTH...TO NEAR 75 ALONG THE SOUTHERN GRAND STRAND. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... AS OF 300 PM SATURDAY...A COLD FRONT WILL HAVE MOVED THROUGH THE ENTIRE FORECAST AREA BEFORE 12Z SUN. THE INFLUX OF DRIER AIR WILL BE STRONGEST AND DEEPEST ACROSS THE NORTHERN ZONES SUN. THE DRY AIR WILL BE ESPECIALLY PRONOUNCED IN THE MID LEVELS...ABOVE 10-12 KFT. AN ONSHORE FLOW BELOW 10 KFT WILL KEEP THE LOWER LEVELS OF THE COLUMN MORE MOIST. A SHORTWAVE PUSHING DOWN THE SOUTHEAST COAST MAY TOUCH OFF SOME SHALLOWER CONVECTION. WILL CARRY A SLIGHT CHANCE TO SMALL CHANCE OF SHOWERS AND THUNDERSTORMS ON SUNDAY WITH THE RISK DECREASING FROM NORTH TO SOUTH AS THE DAY PROGRESSES. PRECIPITABLE WATER VALUES WILL BE DROPPING BELOW THREE-QUARTERS OF AN INCH SUN NIGHT AS MUCH DRIER AIR OVERWHELMS THE COLUMN DOWN TO THE SURFACE. THUS...WILL NOT CARRY ANY POPS BEYOND NIGHTFALL. A DEEP AND TIGHTENING NE FLOW WILL BE PRESENT MON AND MON NIGHT AS A WEDGE OF HIGH PRESSURE BUILDS STRONGLY ACROSS WESTERN NORTH CAROLINA AND THE UPSTATE OF SOUTH CAROLINA. AT THE SAME TIME...DEVELOPING TROPICAL LOW PRESSURE ACROSS THE BAHAMAS WILL RESULT IN A TIGHTENING PRESSURE GRADIENT. AN INVERTED TROUGH MAY BEGIN TO DEVELOP DURING THIS TIME AND IF IT COMES CLOSE ENOUGH TO THE COAST...A FEW SHOWERS MAY IMPINGE ONTO THE COAST. AT THIS TIME...WILL KEEP ANY MENTION OF CONVECTION OFFSHORE...BUT SHOW SOME INCREASING CLOUD COVER AS THE COLUMN DOES BEGIN TO MOISTEN BACK UP IN THE LOWER LEVELS. HIGH TEMPS WILL BE MAINLY NEAR TO A FEW DEGREES BELOW NORMAL THIS PERIOD AS WE WILL BE UNDER A NE FLOW REGIME. HIGHS BOTH DAYS WILL BE IN THE MID AND UPPER 80S. DEWPOINTS WILL ALSO BE CONSIDERABLY LOWER THAN RECENT DAYS AND SO FOR MOST...IT WILL BE MUCH MORE PLEASANT. LOWS WILL BE BELOW NORMAL AND MAINLY IN THE MID TO UPPER 60S. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 300 PM SATURDAY...THE EXTENDED CONTINUES TO BE DOMINATED BY MID LEVEL HIGH PRESSURE MOVING FROM THE MISSISSIPPI VALLEY TO THE SOUTHEAST BY NEXT WEEKEND. AT THE SURFACE HIGH PRESSURE WILL BE THE MAIN FEATURE FOR TUESDAY AND WEDNESDAY WITH A COOL NORTHEAST FLOW. THE HIGH BECOMES MORE DIFFUSE THURSDAY...A LITTLE EARLIER THAN PREVIOUS GUIDANCE. THE SYSTEM FOR LATE IN THE WEEK LOOKS CONSIDERABLY WEAKER AS WELL. CHANGES TO THE FORECAST THIS AFTERNOON ARE MINIMAL. I DID INCREASE POPS FOR FRIDAY AND SATURDAY TO MATCH OTHER OFFICES BETTER BUT THE VALUES ARE STILL LOWER THAN THIS TIME YESTERDAY. THE TEMPERATURE FORECAST HAS INCREASED ESPECIALLY FOR THURSDAY AND FRIDAY WITH READINGS NEARING OR EVEN EXCEEDING CLIMATOLOGY SLIGHTLY FOR THESE PERIODS INCLUDING SATURDAY. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 18Z...A COLD FRONT WAS LOCATED IN THE VICINITY OF THE TERMINALS THIS AFTERNOON. ISOLATED SHOWERS WERE DEVELOPING ALONG THE SEA BREEZE AND MAY IMPACT ILM/CRE/MYR DURING THE NEXT FEW HOURS. THE FRONT WILL SHIFT SOUTH OF ALL TERMINALS TONIGHT. OTHER THAN SCATTERED THUNDERSTORMS ALONG THE SEA BREEZE...CONVECTION WILL BE ISOLATED THIS AFTERNOON. HOWEVER...AN UPPER IMPULSE WILL MOVE TOWARDS THE AREA THIS EVENING...WHICH WILL SET OFF MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS THE AREA. STILL SOME UNCERTAINTY INTO THE TIMING AND COVERAGE OF THIS ACTIVITY...BUT HAVE ENOUGH CONFIDENCE TO KEEP VCSH AT THE TERMINALS UNTIL AFTER MIDNIGHT. LIGHT WINDS THIS AFTN WILL BE PRIMARILY FROM THE EAST...WITH MINOR FLUCTUATIONS TO SE OR NE AT TIMES. HEAVIEST SHOWERS SHOULD END N-S TONIGHT. POST FRONTAL MVFR CIGS ARE EXPECTED WITH REASONABLE CONFIDENCE OF POST-FRONTAL IFR AT KFLO/KLBT OVERNIGHT. MVFR SHORTLY AFTER SUNRISE SHOULD IMPROVE TO VFR AT THE NORTHERN AND COASTAL TERMINALS INITIALLY...AND KFLO BY MID MORNING. WINDS WILL BECOME PREDOMINATELY NE 10-15 KT AFTER SUNRISE. EXTENDED OUTLOOK...EXPECT VFR/NSW TO PREVAIL THROUGH TUES AS HIGH PRESSURE RIDGES OVER THE EAST COAST IN THE WAKE OF THE COLD FRONT. A CHANCE OF SHRA WED. VFR/NSW THURS. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM SATURDAY...COLD FRONT IS SLOWLY DROPPING SOUTH ACROSS THE WATERS TODAY...AND ALTHOUGH IS TOUGH TO LOCATE EXACTLY...APPEARS TO BE JUST SOUTH OF MYRTLE BEACH AT THIS TIME. THE WATERS NORTH OF THIS BOUNDARY ARE EXPERIENCING E/NE WINDS OF 5-10 KTS...WHILE SOUTH OF THE FRONT WINDS ARE LIGHT AND VARIABLE. THE EXCEPTION IS ACROSS AMZ250 WHERE WINDS ARE GUSTING UP TO 15 KTS FROM THE NE...THE BEGINNING OF WHAT WILL BE AN INCREASING SURGE TONIGHT. THIS FRONT WILL SLOWLY DROP THROUGH ALL THE WATERS OVERNIGHT...LEAVING INCREASING NE WINDS IN ITS WAKE...AND BY SUNDAY MORNING WINDS WILL BE NE AT 15-20 KTS ACROSS ALL THE WATERS. WAVE HEIGHTS WILL BUILD ON THESE RISING WINDS...SLOWLY AT FIRST TO 2-3 FT TONIGHT...BUT MORE QUICKLY LATE...AND WILL BECOME 3-4 FT WITH A FEW 5 FTERS IN THE NORTHERN WATERS BY SUNDAY MORNING. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 PM SATURDAY...THE GRADIENT WILL BE TIGHTENING UP DURING THIS PERIOD. A NE SURGE SUNDAY WILL BECOME FORTIFIED BY A TIGHTENING PRESSURE GRADIENT BETWEEN HIGH PRESSURE ACROSS THE NORTHEAST U.S. AND A DEVELOPING TROPICAL LOW ACROSS THE BAHAMAS. THIS WILL SERVE TO NOT ONLY PROLONG THE NE FLOW...BUT TO INCREASE ITS MAGNITUDE. THUS...A SMALL CRAFT ADVISORY HAS BEEN ISSUED BEGINNING SUNDAY MORNING. WINDS WILL COMMONLY BE SUSTAINED AT 20 TO 25 KT. A NE FETCH WILL BUILD SEAS TO 4 TO 7 FT AND 8 FT OR HIGHER BEYOND 20 NM. LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 300 PM SATURDAY...THE MARINE COMMUNITY CAN EXPECT A NORTHEAST FLOW TUESDAY ON THE ORDER OF 15-20 KNOTS. THIS FLOW WILL DIMINISH QUITE A BIT WEDNESDAY ESSENTIALLY BECOMING VARIABLE BY DAYS END. FOR THURSDAY A VERY LIGHT FLOW CAN BE EXPECTED AS THE WATERS ARE IN BETWEEN RETREATING HIGH PRESSURE TO THE NORTH AND THE BUILDING BERMUDA RIDGE. WILL LIKELY SEE WINDS MORE INFLUENCED BY THE SEA BREEZE THIS DAY. SIGNIFICANT SEAS CONTINUE TO BE PROBLEMATIC DEPENDING ON THE TRACK AND INTENSITY OF AL96. FORECAST SHOWS 2-6 FEET TUESDAY WITH AN INCREASE MOSTLY IN THE OUTER WATERS WEDNESDAY AND THURSDAY DUE ALMOST EXCLUSIVELY TO INCREASED SWELL COMPONENT FROM THE AFOREMENTIONED SYSTEM. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 AM SUNDAY TO 8 PM EDT MONDAY FOR AMZ250-252-254-256. && $$ NEAR TERM...JDW SHORT TERM...RJD LONG TERM...SHK AVIATION...JDW/MRR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 PM EDT SAT AUG 23 2014 .SYNOPSIS...A COLD FRONT WILL MOVE SOUTH ACROSS SOUTHERN VIRGINIA AND NORTH CAROLINA THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD SOUTH INTO THE REGION WITH COOLER AND DRIER CONDITIONS EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 255 PM SATURDAY... LATEST SURFACE ANALYSIS CONTINUES TO REVEAL A COMPLEX SURFACE PATTERN WITH THE BACK DOOR COLD FRONT NOW EXTENDING FROM WESTERN VIRGINIA EAST NEAR THE VA/NC BORDER AND THEN SOUTHEAST TOWARD THE MID CAROLINA COAST. A SURFACE TROUGH ALSO EXTENDS NORTH TO SOUTHEAST ACROSS THE NC/SC COASTAL REGION SEPARATING AN INCREASINGLY DEEP EASTERLY FLOW AS NOTED BY THE HMT-SEPS WIND PROFILER NEAR NEW BERN. A WEAK SURFACE LOW WAS ALSO ANALYZED JUST NORTH OF KCHS WITH A STEAMY 903/79 OBSERVED AT KGGE. A NORTHWEST FLOW ALOFT DOMINATES THE SYNOPTIC PATTERN WITH SEVERAL WAVES NOTED IN THE FLOW ALONG WITH A STRENGTHENING NORTHERN STREAM JET POISED TO DROP INTO THE MID ATLANTIC...NOTE THE 105KT JET AT 200 HPA AT KIAD THIS MORNING. MORNING RAOBS ACROSS THE CAROLINAS DEPICT A VERY MOIST ATMOSPHERE PRECIPITABLE WATER VALUES OF 120-135% OF NORMAL AT KGSO/KMHX RESPECTIVELY. NOT SURPRISED TO SHEE SHOWERS AND THUNDERSTORMS SLOWLY EXPANDING THIS AFTERNOON GIVEN THE ENHANCED FLOW ALOFT...AT LEAST ONE DISTURBANCE ALOFT OVER WESTERN VA AND MULTIPLE MECHANISMS FOR LOW LEVEL CONVERGENCE. CURRENT RADAR TRENDS DEPICT ONE AREA OF CONVECTION ACROSS THE NORTHERN PIEDMONT OF NC AND SOUTHERN VA IN PROXIMITY TO THE SURFACE FRONT AND A DISTURBANCE IN THE NW FLOW ALOFT. OTHER CONVECTION ACROSS THE COASTAL PLAIN AND COASTAL REGION IS DRIVEN IN A MORE UNSTABLE AIR MASS NEAR THE SURFACE TROUGH. USED A BLEND OF HRRR AND RAP HOURLY PRECIP FIELDS TO GENERATE THE HOURLY POP/QPF/WX GRIDS FOR THIS AFTERNOON AND EVENING. WHILE CONVECTIVE COVERAGE IS EXPECTED TO BE SOMEWHAT GENEROUS...MLCAPE VALUES WILL GENERALLY RANGE LESS THAN 1000 J/KG EXCEPT ACROSS THE SOUTHERN COASTAL PLAIN AND SANDHILLS WHERE VALUES MAY EXCEED 1500 J/KG WHICH SHOULD MINIMIZE CONVECTIVE INTENSITY IN MOST LOCATIONS. THE BEST FLOW ALOFT SHOULD REMAIN IN THE VA/MD/DE REGION WITH BULK SHEAR VALUES IN OUR CWA CLIMBING TO AROUND 25KTS. THE BIGGER THREAT WILL LIKELY BE ASSOCIATED WITH LOCALLY HEAVY RAIN WITH CELLS ORIENTED IN THE NW FLOW THAT REPEATEDLY MOVE OVER A GIVEN AREA. THE CONVECTIVE CONVERGE WILL INCREASE A BIT DURING THE NEXT SEVERAL HOURS WITH THE FOCUS GRADUALLY SHIFTING SOUTH INTO THE EVENING ALTHOUGH ISOLATED SHOWERS OR THUNDERSTORMS ARE POSSIBLE AT ANY TIME. A PROMINENT AREA OF CONVECTION UPSTREAM ACROSS IL/IN IS PROGGED TO WEAKEN AS IT MOVES SOUTHEAST AND SHOULD NOT IMPACT CENTRAL NC. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE UPPER 60S NORTHEAST TO LOWER 70S SOUTHWEST. -BLAES && .SHORT TERM /SUNDAY AND SUNDAY NIGHT /... AS OF 305 PM SATURDAY... THE COLD FRONT WILL HAVE PUSHED WELL SOUTH OF THE REGION BY SUNDAY MORNING WITH COOL HIGH PRESSURE BUILDING INTO CENTRAL NC IN ITS WAKE. WHILE MUCH DRIER AIR WILL MOVE INTO THE REGION AT MID AND UPPER LEVELS...SHALLOW LOW LEVEL MOISTURE WILL LINGER ESPECIALLY IN AN ARC FROM THE WESTERN PIEDMONT INTO THE SOUTHERN PIEDMONT AND EAST TOWARD THE SANDHILLS AND COASTAL PLAIN. A FEW SHOWERS MAY DEVELOP IN THIS REGION...ESPECIALLY EARLY ON SUNDAY...BUT LIMITED MOISTURE AND A CAPPING INVERSION SHOULD PRECLUDE DEEP CONVECTION AND LIMIT PRECIPITATION COVERAGE. A FAIR AMOUNT OF STRATO CUMULUS IS EXPECTED THOUGH. WITH A COOLER AIR MASS AND BELOW NORMAL THICKNESS VALUES... HIGHS ON SUNDAY WILL ONLY RANGE IN THE LOWER TO MID 80S. LOWS SUNDAY NIGHT WILL RANGE IN THE LOWER 60S. -BLAES && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 250 PM SATURDAY... FOR MONDAY THROUGH MID-WEDNESDAY...LOOK FOR FAIR WEATHER WITH NEAR- TO SLIGHTLY-BELOW NORMAL TEMPS (HIGHS IN THE LOW-MID 80S AND LOWS IN THE LOW 60S) AS HIGH PRESSURE BUILDS IN TO THE CAROLINAS FROM THE NORTH EARLY IN THE WEEK AND REMAINS OVER OUR AREA THROUGH MID-WEEK. FORECAST SOUNDINGS SUGGEST PWAT WILL RANGE FROM 0.5-1.0 INCHES DURING THIS TIME...WHICH IS WELL BELOW THE 1.35 INCH NORM FOR LATE AUGUST. A LARGE DEGREE OF UNCERTAINTY EXISTS FOR THE SECOND HALF OF THE WEEK...AS THIS PART OF THE FORECAST IS LARGELY DEPENDENT ON WHAT HAPPENS WITH INVEST 96L. TRACK MODELS HAVE BEEN QUITE SCATTERED AND LITTLE AGREEMENT AMONG THE GEFS/NAEFS MEMBERS. HOWEVER...ITS WORTH NOTING THAT THE TREND IN THE OPERATIONAL GFS HAS BEEN DEVELOPMENT AND SLOW NORTHWARD MOVEMENT E OF FL DURING THE FIRST HALF OF THE WEEK...THEN MOVING NNE ALONG BUT REMAINING OFF THE CAROLINA COAST LATE IN THE WEEK. THE LATEST ECMWF IS SIMILAR WITH THE EVOLUTION OF THIS SYSTEM...BUT IS FASTER AND ITS TRACK REMAINS FURTHER OFF THE COAST...SHOWING THE LOW MOVING NE AWAY FROM THE EAST COAST ON THURSDAY. ESSENTIALLY BOTH OF THESE SOLUTIONS WOULD KEEP CENTRAL NC FAR ENOUGH WEST OF THE SYSTEM SUCH THAT OUR AREA WOULD REMAIN IN FAIR WEATHER DURING THE SECOND HALF OF THE WEEK. TAKING THAT SYSTEM OUT OF THE PICTURE...OUR NEXT CHANCE FOR WET WEATHER WOULD COME DURING THE WEEKEND ASSOCIATED WITH EITHER THE NEXT TROUGH IN THE WESTERLIES (PER GFS) OR INCREASING MOISTURE IN THE RETURN FLOW AROUND THE RIDGE (PER THE ECWMF). IN SUMMARY...LOTS OF UNCERTAINTY FOR THE SECOND HALF OF THE LONG TERM...SO WILL STICK CLOSE TO CLIMO FOR TEMPS AND PERHAPS A LITTLE LOWER THAN CLIMO FOR POPS DURING THIS TIME. && .AVIATION /18Z SATURDAY THROUGH WEDNESDAY/... AS OF 225 PM SATURDAY... AS OF 18Z...SOME MVFR CONDITIONS MAINLY ASSOCIATED WITH CIGS PERSIST ACROSS PARTS OF THE NORTHEAST PIEDMONT AND COASTAL PLAIN. ELSEWHERE VFR CONDITIONS WITH MULTIPLE LOW TO MID CLOUD LAYERS ARE OBSERVED. SCATTERED SHOWERS AND THUNDERSTORMS WILL BECOME MORE NUMEROUS AND MOVE SOUTHEAST THIS AFTERNOON AND EVENING ACROSS CENTRAL NC AS A COLD FRONT AND AN UPPER LEVEL DISTURBANCE TRIGGERS AND THEN MAINTAIN SCATTERED CONVECTION. INITIALLY THE PRECIPITATION WILL BE MOST WIDESPREAD THIS AFTERNOON ACROSS THE COASTAL PLAIN...MAINLY EAST OF THE KRWI AND KFAY TERMINALS. ANOTHER AREA OF SHOWERS AND THUNDERSTORMS WILL ROTATE AND PUSH SOUTH ACROSS THE NORTHERN PIEDMONT THIS AFTERNOON AND THEN GRADUALLY SHIFT SOUTH LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING. THE CONVECTION WILL TEND TO SHIFT SOUTH...WEAKEN AND DECREASE IN COVERAGE LATER THIS EVENING AND OVERNIGHT. EXPECT LOCAL REDUCTIONS TO MVR AND INTERMITTENTLY IFR CONDITIONS IN SHOWERS AND THUNDERSTORMS. PREVAILING CEILINGS WILL ALSO DECREASE OVERNIGHT AS COOLER AIR MOVES INTO THE REGION WITH PERIODS OF IFR CONDITIONS IN LOW CLOUDS AND SOME FOG LIKELY TOWARD DAYBREAK WITH HEATING AND AN INFLUX OF DRIER AIR FROM THE NORTHEAST...CEILINGS SHOULD LIFT A COUPLE OF HOURS AFTER DAYBREAK WITH VFR CONDITIONS PREVAILING BY LATE OR EARLY AFTERNOON. LOOKING FURTHER AHEAD...HIGH PRESSURE AT THE SURFACE AND ALOFT WILL EXTEND INTO THE REGION FOR THE LATE SUNDAY THROUGH WEDNESDAY PERIOD BRINGING A PERIOD OF GENERALLY FAIR WEATHER. EXCEPTIONS WOULD INCLUDE THE POTENTIAL FOR SOME DAYBREAK FOG ON MONDAY AND TUESDAY MORNINGS...ESPECIALLY ACROSS THE COASTAL PLAIN AND PERHAPS A SHOWER ACROSS THE EASTERN SECTIONS IN A PERSISTENT NORTHEAST FLOW. -BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES SHORT TERM...BLAES LONG TERM...NP AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
255 PM EDT SAT AUG 23 2014 .SYNOPSIS...A COLD FRONT WILL MOVE SOUTH ACROSS SOUTHERN VIRGINIA AND NORTH CAROLINA THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD SOUTH INTO THE REGION WITH COOLER AND DRIER CONDITIONS EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 255 PM SATURDAY... LATEST SURFACE ANALYSIS CONTINUES TO REVEAL A COMPLEX SURFACE PATTERN WITH THE BACK DOOR COLD FRONT NOW EXTENDING FROM WESTERN VIRGINIA EAST NEAR THE VA/NC BORDER AND THEN SOUTHEAST TOWARD THE MID CAROLINA COAST. A SURFACE TROUGH ALSO EXTENDS NORTH TO SOUTHEAST ACROSS THE NC/SC COASTAL REGION SEPARATING AN INCREASINGLY DEEP EASTERLY FLOW AS NOTED BY THE HMT-SEPS WIND PROFILER NEAR NEW BERN. A WEAK SURFACE LOW WAS ALSO ANLAYZED JUST NORTH OF KCHS WITH A STEAMY 903/79 OBSERVED AT KGGE. A NORTHWEST FLOW ALOFT DOMINATES THE SYNOPTIC PATTERN WITH SEVERAL WAVES NOTED IN THE FLOW ALONG WITH A STRENGTHENING NORTHERN STREAM JET POISED TO DROP INTO THE MID ATLANTIC...NOTE THE 105KT JET AT 200 HPA AT KIAD THIS MORNING. MORNING RAOBS ACROSS THE CAROLINAS DEPICT A VERY MOIST ATMOSPHERE PRECIPITABLE WATER VALUES OF 120-135% OF NORMAL AT KGSO/KMHX RESPECTIVELY. NOT SURPRISED TO SHEE SHOWERS AND THUNDERSTORMS SLOWLY EXPANDING THIS AFTERNOON GIVEN THE ENHANCED FLOW ALOFT...AT LEAST ONE DISTURBANCE ALOFT OVER WESTERN VA AND MULTIPLE MECHANISMS FOR LOW LEVEL CONVERGENCE. CURRENT RADAR TRENDS DEPICT ONE AREA OF CONVECTION ACROSS THE NORTHERN PIEDMONT OF NC AND SOUTHERN VA IN PROXIMITY TO THE SURFACE FRONT AND A DISTURBANCE IN THE NW FLOW ALOFT. OTHER CONVECTION ACROSS THE COASTAL PLAIN AND COASTAL REGION IS DRIVEN IN A MORE UNSTABLE AIR MASS NEAR THE SURFACE TROUGH. USED A BLEND OF HRRR AND RAP HOURLY PRECIP FIELDS TO GENERATE THE HOURLY POP/QPF/WX GRIDS FOR THIS AFTERNOON AND EVENING. WHILE CONVECTIVE COVERAGE IS EXPECTED TO BE SOMEWHAT GENEROUS...MLCAPE VALUES WILL GENERALLY RANGE LESS THAN 1000 J/KG EXCEPT ACROSS THE SOUTHERN COASTAL PLAIN AND SANDHILLS WHERE VALUES MAY EXCEED 1500 J/KG WHICH SHOULD MINIMIZE CONVECTIVE INTENSITY IN MOST LOCATIONS. THE BEST FLOW ALOFT SHOULD REMAIN IN THE VA/MD/DE REGION WITH BULK SHEAR VALUES IN OUR CWA CLIMBING TO AROUND 25KTS. THE BIGGER THREAT WILL LIKELY BE ASSOCIATED WITH LOCALLY HEAVY RAIN WITH CELLS ORIENTED IN THE NW FLOW THAT REPEATEDLY MOVE OVER A GIVEN AREA. THE CONVECTIVE CONVERGE WILL INCREASE A BIT DURING THE NEXT SEVERAL HOURS WITH THE FOCUS GRADUALLY SHIFTING SOUTH INTO THE EVENING ALTHOUGH ISOLATED SHOWERS OR THUNDERSTORMS ARE POSSIBLE AT ANY TIME. A PROMINENT AREA OF CONVECTION UPSTREAM ACROSS IL/IN IS PROGGED TO WEAKEN AS IT MOVES SOUTHEAST AND SHOULD NOT IMPACT CENTRAL NC. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE UPPER 60S NORTHEAST TO LOWER 70S SOUTHWEST. -BLAES && .SHORT TERM /SUNDAY AND SUNDAY NIGHT /... AS OF 306 AM SATURDAY... SURFACE DRY AIR RIDGE EXTENDS SOUTHWARD INTO NC FROM A PARENT HIGH POSITIONED OVER NORTHERN MID ATLANTIC. THIS SURFACE RIDGE SUPPORTED ALOFT BY A BUILDING UPPER LEVEL RIDGE...STRETCHING FROM THE MID- LOWER MS VALLEY NEWD INTO NEW ENGLAND. NELY LOW LEVEL FLOW WILL ADVECT COOLER DRIER AIR INTO CENTRAL NC. THIS DRIER AIR WILL AID TO DIMINISH ANY RESIDUAL STRATOCU. LOW LEVEL THICKNESSES DROP TO VALUES 15-20M BELOW NORMAL FOR LATE AUGUST. THIS YIELDS MAX TEMPS OF NEAR 80 ACROSS THE FAR NORTH-NW TO LOW/MID 80S FAR SOUTH. MIN TEMPS SUNDAY NIGHT LOW-MD 60S. && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 250 PM SATURDAY... FOR MONDAY THROUGH MID-WEDNESDAY...LOOK FOR FAIR WEATHER WITH NEAR- TO SLIGHTLY-BELOW NORMAL TEMPS (HIGHS IN THE LOW-MID 80S AND LOWS IN THE LOW 60S) AS HIGH PRESSURE BUILDS IN TO THE CAROLINAS FROM THE NORTH EARLY IN THE WEEK AND REMAINS OVER OUR AREA THROUGH MID-WEEK. FORECAST SOUNDINGS SUGGEST PWAT WILL RANGE FROM 0.5-1.0 INCHES DURING THIS TIME...WHICH IS WELL BELOW THE 1.35 INCH NORM FOR LATE AUGUST. A LARGE DEGREE OF UNCERTAINTY EXISTS FOR THE SECOND HALF OF THE WEEK...AS THIS PART OF THE FORECAST IS LARGELY DEPENDENT ON WHAT HAPPENS WITH INVEST 96L. TRACK MODELS HAVE BEEN QUITE SCATTERED AND LITTLE AGREEMENT AMONG THE GEFS/NAEFS MEMBERS. HOWEVER...ITS WORTH NOTING THAT THE TREND IN THE OPERATIONAL GFS HAS BEEN DEVELOPMENT AND SLOW NORTHWARD MOVEMENT E OF FL DURING THE FIRST HALF OF THE WEEK...THEN MOVING NNE ALONG BUT REMAINING OFF THE CAROLINA COAST LATE IN THE WEEK. THE LATEST ECMWF IS SIMILAR WITH THE EVOLUTION OF THIS SYSTEM...BUT IS FASTER AND ITS TRACK REMAINS FURTHER OFF THE COAST...SHOWING THE LOW MOVING NE AWAY FROM THE EAST COAST ON THURSDAY. ESSENTIALLY BOTH OF THESE SOLUTIONS WOULD KEEP CENTRAL NC FAR ENOUGH WEST OF THE SYSTEM SUCH THAT OUR AREA WOULD REMAIN IN FAIR WEATHER DURING THE SECOND HALF OF THE WEEK. TAKING THAT SYSTEM OUT OF THE PICTURE...OUR NEXT CHANCE FOR WET WEATHER WOULD COME DURING THE WEEKEND ASSOCIATED WITH EITHER THE NEXT TROUGH IN THE WESTERLIES (PER GFS) OR INCREASING MOISTURE IN THE RETURN FLOW AROUND THE RIDGE (PER THE ECWMF). IN SUMMARY...LOTS OF UNCERTAINTY FOR THE SECOND HALF OF THE LONG TERM...SO WILL STICK CLOSE TO CLIMO FOR TEMPS AND PERHAPS A LITTLE LOWER THAN CLIMO FOR POPS DURING THIS TIME. && .AVIATION /18Z SATURDAY THROUGH WEDNESDAY/... AS OF 225 PM SATURDAY... AS OF 18Z...SOME MVFR CONDITIONS MAINLY ASSOCIATED WITH CIGS PERSIST ACROSS PARTS OF THE NORTHEAST PIEDMONT AND COASTAL PLAIN. ELSEWHERE VFR CONDITIONS WITH MULTIPLE LOW TO MID CLOUD LAYERS ARE OBSERVED. SCATTERED SHOWERS AND THUNDERSTORMS WILL BECOME MORE NUMEROUS AND MOVE SOUTHEAST THIS AFTERNOON AND EVENING ACROSS CENTRAL NC AS A COLD FRONT AND AN UPPER LEVEL DISTURBANCE TRIGGERS AND THEN MAINTAIN SCATTERED CONVECTION. INITIALLY THE PRECIPITATION WILL BE MOST WIDESPREAD THIS AFTERNOON ACROSS THE COASTAL PLAIN...MAINLY EAST OF THE KRWI AND KFAY TERMINALS. ANOTHER AREA OF SHOWERS AND THUNDERSTORMS WILL ROTATE AND PUSH SOUTH ACROSS THE NORTHERN PIEDMONT THIS AFTERNOON AND THEN GRADUALLY SHIFT SOUTH LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING. THE CONVECTION WILL TEND TO SHIFT SOUTH...WEAKEN AND DECREASE IN COVERAGE LATER THIS EVENING AND OVERNIGHT. EXPECT LOCAL REDUCTIONS TO MVR AND INTERMITTENTLY IFR CONDITIONS IN SHOWERS AND THUNDERSTORMS. PREVAILING CEILINGS WILL ALSO DECREASE OVERNIGHT AS COOLER AIR MOVES INTO THE REGION WITH PERIODS OF IFR CONDITIONS IN LOW CLOUDS AND SOME FOG LIKELY TOWARD DAYBREAK WITH HEATING AND AN INFLUX OF DRIER AIR FROM THE NORTHEAST...CEILINGS SHOULD LIFT A COUPLE OF HOURS AFTER DAYBREAK WITH VFR CONDITIONS PREVAILING BY LATE OR EARLY AFTERNOON. LOOKING FURTHER AHEAD...HIGH PRESSURE AT THE SURFACE AND ALOFT WILL EXTEND INTO THE REGION FOR THE LATE SUNDAY THROUGH WEDNESDAY PERIOD BRINGING A PERIOD OF GENERALLY FAIR WEATHER. EXCEPTIONS WOULD INCLUDE THE POTENTIAL FOR SOME DAYBREAK FOG ON MONDAY AND TUESDAY MORNINGS...ESPECIALLY ACROSS THE COASTAL PLAIN AND PERHAPS A SHOWER ACROSS THE EASTERN SECTIONS IN A PERSISTENT NORTHEAST FLOW. -BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES SHORT TERM...WSS LONG TERM...NP AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
250 PM EDT SAT AUG 23 2014 .SYNOPSIS...A COLD FRONT WILL MOVE SOUTH ACROSS SOUTHERN VIRGINIA AND NORTH CAROLINA THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD SOUTH INTO THE REGION WITH COOLER AND DRIER CONDITIONS EARLY NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... AS OF 1100 AM SATURDAY... LATEST SURFACE ANALYSIS REVEALS A COMPLEX PATTERN WITH THE BACK DOOR COLD FRONT NOW EXTENDING ACROSS NORTHEAST NC INTO SOUTHWESTERN VA AS WELL AS A SURFACE TROUGH EXTENDING ALONG THE NC/SC COAST WITH A WEAK SURFACE LOW CENTERED NEAR KILM. THE MAIN SURGE OF COLDER/DRIER AIR LAGS BEHIND THE FRONT AND IS LOCATED ACROSS EASTERN PA AND THE NORTHERN CHESAPEAKE BAY. A NORTHWEST FLOW DOMINATES THE MID AND UPPER AIR PATTERN ACROSS THE CAROLINAS WITH A STRENGTHENING NORTHERN STREAM JET POISED TO DROP INTO THE MID ATLANTIC THIS AFTERNOON...NOTE THE 105KT JET AT 200 HPA AT KIAD THIS MORNING. THE AIRMASS ACROSS THE REGION IS RATHER MOIST WITH PW VALUES OF 120-135% OF NORMAL AT KGSO/KMHX RESPECTIVELY. WITH THE ENHANCED FLOW ALOFT AND MULTIPLE MECHANISMS FOR LOCAL CONVERGENCE...NOT SURPRISED THAT HIGH RESOLUTION GUIDANCE SUGGESTS FAIRLY DECENT CONVECTIVE COVERAGE FOR THIS AFTERNOON. SHOWERS HAVE ALREADY BEGUN TO BLOSSOM IN SOUTHERN VA IN PROXIMITY TO THE SURFACE FRONT AND A DISTURBANCE IN THE NW FLOW ALOFT. OTHER CONVECTION IS BUBBLING UP IN THE COASTAL PLAIN AND COASTAL REGION NEAR THE SURFACE TROUGH. USED A BLEND OF HRRR AND RAP HOURLY PRECIP FIELDS TO GENERATE THE HOURLY POP/QPF/WX GRIDS THIS AFTERNOON. WHILE CONVECTIVE COVERAGE IS EXPECTED TO BE SOMEWHAT GENEROUS...ONLY A WEAKLY UNSTABLE AIRMASS WITH MLCAPE VALUES LESS THAN 1000 SHOULD MINIMIZE OVERAL INTENSITY. THE BEST FLOW ALOFT SHOULD REMAIN IN THE VA/MD/DE REGION WITH BULK SHEAR VALUES IN OUR CWA CLIMBING TO AROUND 2 5KTS. THE BIGGER THREAT WILL LIKELY BE ASSOCIATED WITH LOCALLY HEAVY RAIN WITH CELLS ORIENTED IN THE NW FLOW THAT REPEATEDLY MOVE OVER A GIVEN AREA. CLOUD COVER AND SCT CONVECTION SHOULD HOLD TEMPERATURES DOWN A BIT...ESPECIALLY IN THE NORTHEAST. A LITTLE BIT MORE SUNSHINE ACROSS THE SOUTHERN PIEDMONT AND SANDHILLS SHOULD ALLOW TEMPERATURES TO WARM TO AROUND OR JUST ABOVE 90. -BLAES MAIN AREA OF CONVECTION IS FORECAST TO BEGIN PUSHING TO THE SOUTH OF THE AREA BY THIS EVENING... WHILE THE LOW LEVEL FRONTAL ZONE BEGINS TO MOVE INTO THE AREA. THIS SHOULD YIELD A CONTINUED LOW END CHANCE OF AT LEAST SOME SHOWERS THOUGH. WITH A LOW LEVEL EAST TO NORTHEASTERLY FLOW TONIGHT... LOW STRATUS IS APT TO DEVELOP... WITH PATCHY LIGHT DRIZZLE EVEN. THE MAIN PUSH OF THE COOLER AIR SHOULD HOLD OFF UNTIL AFTER DAYBREAK SUNDAY. THUS... EXPECT LOW TEMPS WILL BE IN THE UPPER 60S TO LOWER 70S. SUNDAY: SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA ON SUNDAY... ALONG WITH DRIER AIR ALOFT. THIS WILL YIELD MUCH DRIER CONDITIONS ON SUNDAY... WITH SKIES BECOMING PARTLY SUNNY BY AFTERNOON. HIGH TEMPS WILL BE COOLER... AROUND 80 NORTHEAST TO MID 80S SOUTH/SOUTHWEST. CAN`T RULE OUT SOME LIGHT SHOWERS IN THE EAST TO EAST-NORTHEASTERLY LOW LEVEL FLOW IN THE MORNING TO EARLY AFTERNOON THOUGH. && .SHORT TERM /SUNDAY NIGHT AND MONDAY/... AS OF 306 AM SATURDAY... SURFACE DRY AIR RIDGE EXTENDS SOUTHWARD INTO NC FROM A PARENT HIGH POSITIONED OVER NORTHERN MID ATLANTIC. THIS SURFACE RIDGE SUPPORTED ALOFT BY A BUILDING UPPER LEVEL RIDGE...STRETCHING FROM THE MID- LOWER MS VALLEY NEWD INTO NEW ENGLAND. NELY LOW LEVEL FLOW WILL ADVECT COOLER DRIER AIR INTO CENTRAL NC. THIS DRIER AIR WILL AID TO DIMINISH ANY RESIDUAL STRATOCU. LOW LEVEL THICKNESSES DROP TO VALUES 15-20M BELOW NORMAL FOR LATE AUGUST. THIS YIELDS MAX TEMPS OF NEAR 80 ACROSS THE FAR NORTH-NW TO LOW/MID 80S FAR SOUTH. MIN TEMPS SUNDAY NIGHT LOW-MD 60S. && .LONG TERM /MONDAY THROUGH SATURDAY/... AS OF 250 PM SATURDAY... FOR MONDAY THROUGH MID-WEDNESDAY...LOOK FOR FAIR WEATHER WITH NEAR- TO SLIGHTLY-BELOW NORMAL TEMPS (HIGHS IN THE LOW-MID 80S AND LOWS IN THE LOW 60S) AS HIGH PRESSURE BUILDS IN TO THE CAROLINAS FROM THE NORTH EARLY IN THE WEEK AND REMAINS OVER OUR AREA THROUGH MID-WEEK. FORECAST SOUNDINGS SUGGEST PWAT WILL RANGE FROM 0.5-1.0 INCHES DURING THIS TIME...WHICH IS WELL BELOW THE 1.35 INCH NORM FOR LATE AUGUST. A LARGE DEGREE OF UNCERTAINTY EXISTS FOR THE SECOND HALF OF THE WEEK...AS THIS PART OF THE FORECAST IS LARGELY DEPENDENT ON WHAT HAPPENS WITH INVEST 96L. TRACK MODELS HAVE BEEN QUITE SCATTERED AND LITTLE AGREEMENT AMONG THE GEFS/NAEFS MEMBERS. HOWEVER...ITS WORTH NOTING THAT THE TREND IN THE OPERATIONAL GFS HAS BEEN DEVELOPMENT AND SLOW NORTHWARD MOVEMENT E OF FL DURING THE FIRST HALF OF THE WEEK...THEN MOVING NNE ALONG BUT REMAINING OFF THE CAROLINA COAST LATE IN THE WEEK. THE LATEST ECMWF IS SIMILAR WITH THE EVOLUTION OF THIS SYSTEM...BUT IS FASTER AND ITS TRACK REMAINS FURTHER OFF THE COAST...SHOWING THE LOW MOVING NE AWAY FROM THE EAST COAST ON THURSDAY. ESSENTIALLY BOTH OF THESE SOLUTIONS WOULD KEEP CENTRAL NC FAR ENOUGH WEST OF THE SYSTEM SUCH THAT OUR AREA WOULD REMAIN IN FAIR WEATHER DURING THE SECOND HALF OF THE WEEK. TAKING THAT SYSTEM OUT OF THE PICTURE...OUR NEXT CHANCE FOR WET WEATHER WOULD COME DURING THE WEEKEND ASSOCIATED WITH EITHER THE NEXT TROUGH IN THE WESTERLIES (PER GFS) OR INCREASING MOISTURE IN THE RETURN FLOW AROUND THE RIDGE (PER THE ECWMF). IN SUMMARY...LOTS OF UNCERTAINTY FOR THE SECOND HALF OF THE LONG TERM...SO WILL STICK CLOSE TO CLIMO FOR TEMPS AND PERHAPS A LITTLE LOWER THAN CLIMO FOR POPS DURING THIS TIME. && .AVIATION /18Z SATURDAY THROUGH WEDNESDAY/... AS OF 225 PM SATURDAY... AS OF 18Z...SOME MVFR CONDITIONS MAINLY ASSOCIATED WITH CIGS PERSIST ACROSS PARTS OF THE NORTHEAST PIEDMONT AND COASTAL PLAIN. ELSEWHERE VFR CONDITIONS WITH MULTIPLE LOW TO MID CLOUD LAYERS ARE OBSERVED. SCATTERED SHOWERS AND THUNDERSTORMS WILL BECOME MORE NUMEROUS AND MOVE SOUTHEAST THIS AFTERNOON AND EVENING ACROSS CENTRAL NC AS A COLD FRONT AND AN UPPER LEVEL DISTURBANCE TRIGGERS AND THEN MAINTAIN SCATTERED CONVECTION. INITIALLY THE PRECIPITATION WILL BE MOST WIDESPREAD THIS AFTERNOON ACROSS THE COASTAL PLAIN...MAINLY EAST OF THE KRWI AND KFAY TERMINALS. ANOTHER AREA OF SHOWERS AND THUNDERSTORMS WILL ROTATE AND PUSH SOUTH ACROSS THE NORTHERN PIEDMONT THIS AFTERNOON AND THEN GRADUALLY SHIFT SOUTH LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING. THE CONVECTION WILL TEND TO SHIFT SOUTH...WEAKEN AND DECREASE IN COVERAGE LATER THIS EVENING AND OVERNIGHT. EXPECT LOCAL REDUCTIONS TO MVR AND INTERMITTENTLY IFR CONDITIONS IN SHOWERS AND THUNDERSTORMS. PREVAILING CEILINGS WILL ALSO DECREASE OVERNIGHT AS COOLER AIR MOVES INTO THE REGION WITH PERIODS OF IFR CONDITIONS IN LOW CLOUDS AND SOME FOG LIKELY TOWARD DAYBREAK WITH HEATING AND AN INFLUX OF DRIER AIR FROM THE NORTHEAST...CEILINGS SHOULD LIFT A COUPLE OF HOURS AFTER DAYBREAK WITH VFR CONDITIONS PREVAILING BY LATE OR EARLY AFTERNOON. LOOKING FURTHER AHEAD...HIGH PRESSURE AT THE SURFACE AND ALOFT WILL EXTEND INTO THE REGION FOR THE LATE SUNDAY THROUGH WEDNESDAY PERIOD BRINGING A PERIOD OF GENERALLY FAIR WEATHER. EXCEPTIONS WOULD INCLUDE THE POTENTIAL FOR SOME DAYBREAK FOG ON MONDAY AND TUESDAY MORNINGS...ESPECIALLY ACROSS THE COASTAL PLAIN AND PERHAPS A SHOWER ACROSS THE EASTERN SECTIONS IN A PERSISTENT NORTHEAST FLOW. -BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES/BSD SHORT TERM...WSS LONG TERM...NP AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
225 PM EDT SAT AUG 23 2014 .SYNOPSIS...A COLD FRONT WILL MOVE SOUTH ACROSS SOUTHERN VIRGINIA AND NORTH CAROLINA THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD SOUTH INTO THE REGION WITH COOLER AND DRIER CONDITIONS EARLY NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... AS OF 1100 AM SATURDAY... LATEST SURFACE ANALYSIS REVEALS A COMPLEX PATTERN WITH THE BACK DOOR COLD FRONT NOW EXTENDING ACROSS NORTHEAST NC INTO SOUTHWESTERN VA AS WELL AS A SURFACE TROUGH EXTENDING ALONG THE NC/SC COAST WITH A WEAK SURFACE LOW CENTERED NEAR KILM. THE MAIN SURGE OF COLDER/DRIER AIR LAGS BEHIND THE FRONT AND IS LOCATED ACROSS EASTERN PA AND THE NORTHERN CHESAPEAKE BAY. A NORTHWEST FLOW DOMINATES THE MID AND UPPER AIR PATTERN ACROSS THE CAROLINAS WITH A STRENGTHENING NORTHERN STREAM JET POISED TO DROP INTO THE MID ATLANTIC THIS AFTERNOON...NOTE THE 105KT JET AT 200 HPA AT KIAD THIS MORNING. THE AIRMASS ACROSS THE REGION IS RATHER MOIST WITH PW VALUES OF 120-135% OF NORMAL AT KGSO/KMHX RESPECTIVELY. WITH THE ENHANCED FLOW ALOFT AND MULTIPLE MECHANISMS FOR LOCAL CONVERGENCE...NOT SURPRISED THAT HIGH RESOLUTION GUIDANCE SUGGESTS FAIRLY DECENT CONVECTIVE COVERAGE FOR THIS AFTERNOON. SHOWERS HAVE ALREADY BEGUN TO BLOSSOM IN SOUTHERN VA IN PROXIMITY TO THE SURFACE FRONT AND A DISTURBANCE IN THE NW FLOW ALOFT. OTHER CONVECTION IS BUBBLING UP IN THE COASTAL PLAIN AND COASTAL REGION NEAR THE SURFACE TROUGH. USED A BLEND OF HRRR AND RAP HOURLY PRECIP FIELDS TO GENERATE THE HOURLY POP/QPF/WX GRIDS THIS AFTERNOON. WHILE CONVECTIVE COVERAGE IS EXPECTED TO BE SOMEWHAT GENEROUS...ONLY A WEAKLY UNSTABLE AIRMASS WITH MLCAPE VALUES LESS THAN 1000 SHOULD MINIMIZE OVERAL INTENSITY. THE BEST FLOW ALOFT SHOULD REMAIN IN THE VA/MD/DE REGION WITH BULK SHEAR VALUES IN OUR CWA CLIMBING TO AROUND 2 5KTS. THE BIGGER THREAT WILL LIKELY BE ASSOCIATED WITH LOCALLY HEAVY RAIN WITH CELLS ORIENTED IN THE NW FLOW THAT REPEATEDLY MOVE OVER A GIVEN AREA. CLOUD COVER AND SCT CONVECTION SHOULD HOLD TEMPERATURES DOWN A BIT...ESPECIALLY IN THE NORTHEAST. A LITTLE BIT MORE SUNSHINE ACROSS THE SOUTHERN PIEDMONT AND SANDHILLS SHOULD ALLOW TEMPERATURES TO WARM TO AROUND OR JUST ABOVE 90. -BLAES MAIN AREA OF CONVECTION IS FORECAST TO BEGIN PUSHING TO THE SOUTH OF THE AREA BY THIS EVENING... WHILE THE LOW LEVEL FRONTAL ZONE BEGINS TO MOVE INTO THE AREA. THIS SHOULD YIELD A CONTINUED LOW END CHANCE OF AT LEAST SOME SHOWERS THOUGH. WITH A LOW LEVEL EAST TO NORTHEASTERLY FLOW TONIGHT... LOW STRATUS IS APT TO DEVELOP... WITH PATCHY LIGHT DRIZZLE EVEN. THE MAIN PUSH OF THE COOLER AIR SHOULD HOLD OFF UNTIL AFTER DAYBREAK SUNDAY. THUS... EXPECT LOW TEMPS WILL BE IN THE UPPER 60S TO LOWER 70S. SUNDAY: SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA ON SUNDAY... ALONG WITH DRIER AIR ALOFT. THIS WILL YIELD MUCH DRIER CONDITIONS ON SUNDAY... WITH SKIES BECOMING PARTLY SUNNY BY AFTERNOON. HIGH TEMPS WILL BE COOLER... AROUND 80 NORTHEAST TO MID 80S SOUTH/SOUTHWEST. CAN`T RULE OUT SOME LIGHT SHOWERS IN THE EAST TO EAST-NORTHEASTERLY LOW LEVEL FLOW IN THE MORNING TO EARLY AFTERNOON THOUGH. && .SHORT TERM /SUNDAY NIGHT AND MONDAY/... AS OF 306 AM SATURDAY... SURFACE DRY AIR RIDGE EXTENDS SOUTHWARD INTO NC FROM A PARENT HIGH POSITIONED OVER NORTHERN MID ATLANTIC. THIS SURFACE RIDGE SUPPORTED ALOFT BY A BUILDING UPPER LEVEL RIDGE...STRETCHING FROM THE MID- LOWER MS VALLEY NEWD INTO NEW ENGLAND. NELY LOW LEVEL FLOW WILL ADVECT COOLER DRIER AIR INTO CENTRAL NC. THIS DRIER AIR WILL AID TO DIMINISH ANY RESIDUAL STRATOCU. LOW LEVEL THICKNESSES DROP TO VALUES 15-20M BELOW NORMAL FOR LATE AUGUST. THIS YIELDS MAX TEMPS OF NEAR 80 ACROSS THE FAR NORTH-NW TO LOW/MID 80S FAR SOUTH. MIN TEMPS SUNDAY NIGHT LOW-MD 60S. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 306 AM SATURDAY... MONDAY NIGHT THROUGH THURSDAY...TRANQUIL WEATHER PATTERN WILL CONTINUE. UPPER LEVEL RIDGE WILL REMAIN HIGHLY AMPLIFIED UNTIL LATE WEDNESDAY INTO THURSDAY AT WHICH TIME A S/W IN THE NORTHERN STREAM WILL BE EXITING THE NORTHERN PLAINS INTO THE GREAT LAKES. THE APPROACH OF THIS SYSTEM WILL WEAKEN/SUPPRESS THE UPPER RIDGE SOUTHWARD. ASSOCIATED SFC RIDGE WILL MAINTAIN A DRY WEATHER REGIME WITH MODERATING TEMPERATURES THROUGH THURSDAY. MAX TEMPS TUESDAY NEAR 80 NORTH TO LOWER 80S SOUTH WARM TO THE MID-UPPER 80S BY THURSDAY. MIN TEMPS ALSO GRADUALLY MODIFY...FROM THE UPPER 50S-LOWER 60S TUESDAY MORNING TO THE MID 60S THURSDAY MORNING. FORECAST CONFIDENCE WANES THURSDAY INTO FRIDAY AS GFS IS MUCH FASTER WITH THE APPROACH OF THE NORTHERN STREAM S/W TOWARD THE EAST COAST VERSUS THE SLOWER ECMWF. ALSO OF CONCERN IS THE EVENTUAL TRACK OF THE TROPICAL SYSTEM THAT IS EXPECTED TO TRACK PARALLEL BUT OFFSHORE OF THE SE U.S. COAST. LATEST MODEL GUIDANCE (MAINLY ECMWF) HAS SHIFTED A LITTLE MORE TO THE WEST...WITH MAJOR TIMING DIFFERENCES (ECMWF MUCH FASTER COMPARED TO THE GFS). WITH THE TROPICAL SYSTEM OFFSHORE AND A TROUGH IN THE VICINITY OF THE GREAT LAKES/MID MS VALLEY...WOULD EXPECT A NARROW RIDGE OVER THE CAROLINAS. UNTIL THE DIFFERENCES ARE RESOLVED...FAVOR A WARM AND MAINLY DRY FORECAST FOR THE END OF THE WORK WEEK. HAVE WARMED TEMPS INTO THE MID 80-AROUND 90 FOR MAX TEMPS FRIDAY WHILE DECREASED RAIN CHANCE TO SLIGHT CHANCE. && .AVIATION /18Z SATURDAY THROUGH WEDNESDAY/... AS OF 225 PM SATURDAY... AS OF 18Z...SOME MVFR CONDITIONS MAINLY ASSOCIATED WITH CIGS PERSIST ACROSS PARTS OF THE NORTHEAST PIEDMONT AND COASTAL PLAIN. ELSEWHERE VFR CONDITIONS WITH MULTIPLE LOW TO MID CLOUD LAYERS ARE OBSERVED. SCATTERED SHOWERS AND THUNDERSTORMS WILL BECOME MORE NUMEROUS AND MOVE SOUTHEAST THIS AFTERNOON AND EVENING ACROSS CENTRAL NC AS A COLD FRONT AND AN UPPER LEVEL DISTURBANCE TRIGGERS AND THEN MAINTAIN SCATTERED CONVECTION. INITIALLY THE PRECIPITATION WILL BE MOST WIDESPREAD THIS AFTERNOON ACROSS THE COASTAL PLAIN...MAINLY EAST OF THE KRWI AND KFAY TERMINALS. ANOTHER AREA OF SHOWERS AND THUNDERSTORMS WILL ROTATE AND PUSH SOUTH ACROSS THE NORTHERN PIEDMONT THIS AFTERNOON AND THEN GRADUALLY SHIFT SOUTH LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING. THE CONVECTION WILL TEND TO SHIFT SOUTH...WEAKEN AND DECREASE IN COVERAGE LATER THIS EVENING AND OVERNIGHT. EXPECT LOCAL REDUCTIONS TO MVR AND INTERMITTENTLY IFR CONDITIONS IN SHOWERS AND THUNDERSTORMS. PREVAILING CEILINGS WILL ALSO DECREASE OVERNIGHT AS COOLER AIR MOVES INTO THE REGION WITH PERIODS OF IFR CONDITIONS IN LOW CLOUDS AND SOME FOG LIKELY TOWARD DAYBREAK WITH HEATING AND AN INFLUX OF DRIER AIR FROM THE NORTHEAST...CEILINGS SHOULD LIFT A COUPLE OF HOURS AFTER DAYBREAK WITH VFR CONDITIONS PREVAILING BY LATE OR EARLY AFTERNOON. LOOKING FURTHER AHEAD...HIGH PRESSURE AT THE SURFACE AND ALOFT WILL EXTEND INTO THE REGION FOR THE LATE SUNDAY THROUGH WEDNESDAY PERIOD BRINGING A PERIOD OF GENERALLY FAIR WEATHER. EXCEPTIONS WOULD INCLUDE THE POTENTIAL FOR SOME DAYBREAK FOG ON MONDAY AND TUESDAY MORNINGS...ESPECIALLY ACROSS THE COASTAL PLAIN AND PERHAPS A SHOWER ACROSS THE EASTERN SECTIONS IN A PERSISTENT NORTHEAST FLOW. -BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES/BSD SHORT TERM...WSS LONG TERM...WSS AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1100 AM EDT SAT AUG 23 2014 .SYNOPSIS...A COLD FRONT WILL MOVE SOUTH ACROSS SOUTHERN VIRGINIA AND NORTH CAROLINA THIS AFTERNOON AND TONIGHT. HIGH PRESSURE WILL BUILD SOUTH INTO THE REGION WITH COOLER AND DRIER CONDITIONS EARLY NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... AS OF 1100 AM SATURDAY... LATEST SURFACE ANALYSIS REVEALS A COMPLEX PATTERN WITH THE BACK DOOR COLD FRONT NOW EXTENDING ACROSS NORTHEAST NC INTO SOUTHWESTERN VA AS WELL AS A SURFACE TROUGH EXTENDING ALONG THE NC/SC COAST WITH A WEAK SURFACE LOW CENTERED NEAR KILM. THE MAIN SURGE OF COLDER/DRIER AIR LAGS BEHIND THE FRONT AND IS LOCATED ACROSS EASTERN PA AND THE NORTHERN CHESAPEAKE BAY. A NORTHWEST FLOW DOMINATES THE MID AND UPPER AIR PATTERN ACROSS THE CAROLINAS WITH A STRENGTHENING NORTHERN STREAM JET POISED TO DROP INTO THE MID ATLANTIC THIS AFTERNOON...NOTE THE 105KT JET AT 200 HPA AT KIAD THIS MORNING. THE AIRMASS ACROSS THE REGION IS RATHER MOIST WITH PW VALUES OF 120-135% OF NORMAL AT KGSO/KMHX RESPECTIVELY. WITH THE ENHANCED FLOW ALOFT AND MULTIPLE MECHANISMS FOR LOCAL CONVERGENCE...NOT SURPRISED THAT HIGH RESOLUTION GUIDANCE SUGGESTS FAIRLY DECENT CONVECTIVE COVERAGE FOR THIS AFTERNOON. SHOWERS HAVE ALREADY BEGUN TO BLOSSOM IN SOUTHERN VA IN PROXIMITY TO THE SURFACE FRONT AND A DISTURBANCE IN THE NW FLOW ALOFT. OTHER CONVECTION IS BUBBLING UP IN THE COASTAL PLAIN AND COASTAL REGION NEAR THE SURFACE TROUGH. USED A BLEND OF HRRR AND RAP HOURLY PRECIP FIELDS TO GENERATE THE HOURLY POP/QPF/WX GRIDS THIS AFTERNOON. WHILE CONVECTIVE COVERAGE IS EXPECTED TO BE SOMEWHAT GENEROUS...ONLY A WEAKLY UNSTABLE AIRMASS WITH MLCAPE VALUES LESS THAN 1000 SHOULD MINIMIZE OVERAL INTENSITY. THE BEST FLOW ALOFT SHOULD REMAIN IN THE VA/MD/DE REGION WITH BULK SHEAR VALUES IN OUR CWA CLIMBING TO AROUND 2 5KTS. THE BIGGER THREAT WILL LIKELY BE ASSOCIATED WITH LOCALLY HEAVY RAIN WITH CELLS ORIENTED IN THE NW FLOW THAT REPEATEDLY MOVE OVER A GIVEN AREA. CLOUD COVER AND SCT CONVECTION SHOULD HOLD TEMPERATURES DOWN A BIT...ESPECIALLY IN THE NORTHEAST. A LITTLE BIT MORE SUNSHINE ACROSS THE SOUTHERN PIEDMONT AND SANDHILLS SHOULD ALLOW TEMPERATURES TO WARM TO AROUND OR JUST ABOVE 90. -BLAES MAIN AREA OF CONVECTION IS FORECAST TO BEGIN PUSHING TO THE SOUTH OF THE AREA BY THIS EVENING... WHILE THE LOW LEVEL FRONTAL ZONE BEGINS TO MOVE INTO THE AREA. THIS SHOULD YIELD A CONTINUED LOW END CHANCE OF AT LEAST SOME SHOWERS THOUGH. WITH A LOW LEVEL EAST TO NORTHEASTERLY FLOW TONIGHT... LOW STRATUS IS APT TO DEVELOP... WITH PATCHY LIGHT DRIZZLE EVEN. THE MAIN PUSH OF THE COOLER AIR SHOULD HOLD OFF UNTIL AFTER DAYBREAK SUNDAY. THUS... EXPECT LOW TEMPS WILL BE IN THE UPPER 60S TO LOWER 70S. SUNDAY: SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA ON SUNDAY... ALONG WITH DRIER AIR ALOFT. THIS WILL YIELD MUCH DRIER CONDITIONS ON SUNDAY... WITH SKIES BECOMING PARTLY SUNNY BY AFTERNOON. HIGH TEMPS WILL BE COOLER... AROUND 80 NORTHEAST TO MID 80S SOUTH/SOUTHWEST. CAN`T RULE OUT SOME LIGHT SHOWERS IN THE EAST TO EAST-NORTHEASTERLY LOW LEVEL FLOW IN THE MORNING TO EARLY AFTERNOON THOUGH. && .SHORT TERM /SUNDAY NIGHT AND MONDAY/... AS OF 306 AM SATURDAY... SURFACE DRY AIR RIDGE EXTENDS SOUTHWARD INTO NC FROM A PARENT HIGH POSITIONED OVER NORTHERN MID ATLANTIC. THIS SURFACE RIDGE SUPPORTED ALOFT BY A BUILDING UPPER LEVEL RIDGE...STRETCHING FROM THE MID- LOWER MS VALLEY NEWD INTO NEW ENGLAND. NELY LOW LEVEL FLOW WILL ADVECT COOLER DRIER AIR INTO CENTRAL NC. THIS DRIER AIR WILL AID TO DIMINISH ANY RESIDUAL STRATOCU. LOW LEVEL THICKNESSES DROP TO VALUES 15-20M BELOW NORMAL FOR LATE AUGUST. THIS YIELDS MAX TEMPS OF NEAR 80 ACROSS THE FAR NORTH-NW TO LOW/MID 80S FAR SOUTH. MIN TEMPS SUNDAY NIGHT LOW-MD 60S. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 306 AM SATURDAY... MONDAY NIGHT THROUGH THURSDAY...TRANQUIL WEATHER PATTERN WILL CONTINUE. UPPER LEVEL RIDGE WILL REMAIN HIGHLY AMPLIFIED UNTIL LATE WEDNESDAY INTO THURSDAY AT WHICH TIME A S/W IN THE NORTHERN STREAM WILL BE EXITING THE NORTHERN PLAINS INTO THE GREAT LAKES. THE APPROACH OF THIS SYSTEM WILL WEAKEN/SUPPRESS THE UPPER RIDGE SOUTHWARD. ASSOCIATED SFC RIDGE WILL MAINTAIN A DRY WEATHER REGIME WITH MODERATING TEMPERATURES THROUGH THURSDAY. MAX TEMPS TUESDAY NEAR 80 NORTH TO LOWER 80S SOUTH WARM TO THE MID-UPPER 80S BY THURSDAY. MIN TEMPS ALSO GRADUALLY MODIFY...FROM THE UPPER 50S-LOWER 60S TUESDAY MORNING TO THE MID 60S THURSDAY MORNING. FORECAST CONFIDENCE WANES THURSDAY INTO FRIDAY AS GFS IS MUCH FASTER WITH THE APPROACH OF THE NORTHERN STREAM S/W TOWARD THE EAST COAST VERSUS THE SLOWER ECMWF. ALSO OF CONCERN IS THE EVENTUAL TRACK OF THE TROPICAL SYSTEM THAT IS EXPECTED TO TRACK PARALLEL BUT OFFSHORE OF THE SE U.S. COAST. LATEST MODEL GUIDANCE (MAINLY ECMWF) HAS SHIFTED A LITTLE MORE TO THE WEST...WITH MAJOR TIMING DIFFERENCES (ECMWF MUCH FASTER COMPARED TO THE GFS). WITH THE TROPICAL SYSTEM OFFSHORE AND A TROUGH IN THE VICINITY OF THE GREAT LAKES/MID MS VALLEY...WOULD EXPECT A NARROW RIDGE OVER THE CAROLINAS. UNTIL THE DIFFERENCES ARE RESOLVED...FAVOR A WARM AND MAINLY DRY FORECAST FOR THE END OF THE WORK WEEK. HAVE WARMED TEMPS INTO THE MID 80-AROUND 90 FOR MAX TEMPS FRIDAY WHILE DECREASED RAIN CHANCE TO SLIGHT CHANCE. && .AVIATION /11Z SATURDAY THROUGH WEDNESDAY/... AS OF 655 AM SATURDAY... A FEW LIGHT ISOLATED TO LOCALLY SCATTERED SHOWERS CONTINUE TO MOVE ACROSS NORTHEAST PORTIONS OF CENTRAL NC THIS MORNING... POSSIBLY AFFECTING KRDU AND KRWI FOR THE NEXT COUPLE OF HOURS. HOWEVER... CONDITIONS ARE GENERALLY EXPECTED TO REMAIN VFR WITH THESE SHOWERS. GREATER CONVECTIVE COVERAGE IS EXPECTED LATER THIS MORNING INTO THE AFTERNOON AS A SERIES OF UPPER LEVEL DISTURBANCES TRACK S/SSE ACROSS THE CAROLINAS AND A BACK DOOR COLD FRONT/PRE-FRONTAL TROUGH PROGRESSES TOWARDS CENTRAL NC FROM THE N/NE. THUS... WILL MENTION A TEMPO GROUP FOR SHOWERS AND SUB-VFR CONDITIONS IN THE TAFS FOR THE AFTERNOON. THUNDERSTORMS WILL BE POSSIBLE AS WELL... BUT WILL HOLD OFF ADDING THUNDER UNTIL WE HAVE A HIGHER CONFIDENCE THAT A GIVEN LOCATION WILL BE AFFECTED BY A THUNDERSTORM. THE STRONGEST STORMS WILL HAVE THE POTENTIAL TO PRODUCE IFR/LIFR VISBYS AND STRONG WIND GUSTS. IFR TO POSSIBLY EVEN LIFR CEILINGS WILL BE POSSIBLE IN THE WAKE OF THE BACKDOOR COLD FRONT TONIGHT THROUGH MID-DAY SUNDAY...THOUGH COVERAGE AND DURATION REMAIN A BIT UNCERTAIN (HIGHEST CONFIDENCES OF SUB-VFR CONDITIONS AT KGSO/KINT). AN UPPER LEVEL RIDGE CENTERED IN VICINITY OF THE SOUTHERN APPALACHIANS SHOULD RESULT IN BETTER-THAN- NORMAL CHANCES FOR VFR CONDITIONS MON-WED...THOUGH A PERSISTENT E/NE LOW-LEVEL FLOW MAY ALLOW ADEQUATE MOISTURE FOR LOW-TOPPED SHOWER ACTIVITY...ESP AT THE EASTERN TERMINALS (FAY/RWI). && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLAES NEAR TERM...BLAES/BSD SHORT TERM...WSS LONG TERM...WSS AVIATION...BSD/VINCENT
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
146 AM EDT SAT AUG 23 2014 .SYNOPSIS... A COLD FRONT WILL SLIP SOUTHWARD INTO THE AREA SATURDAY. THIS FRONT WILL BRING A GOOD CHANCE FOR SHOWERS AND THUNDERSTORMS SATURDAY.. .BEFORE MUCH COOLER AND DRIER AIR FILTERS INTO THE REGION FOR SUNDAY. HIGH PRESSURE EXPANDING SOUTH FROM NEW ENGLAND WILL BRING COOL AND DRY WEATHER FOR THE FIRST HALF OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1:40 AM SATURDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSIONS FOLLOW: ALTHOUGH IT AFFECTED ONLY A SMALL PORTION OF OUR FORECAST AREA THIS EVENING`S STORMS WERE IMPRESSIVE. WIND GUSTS WERE MEASURED AS HIGH AS 47 MPH AT WRIGHTSVILLE BEACH...42 MPH AT THE WILMINGTON STATE PORT...AND 39 MPH AT THE WILMINGTON AIRPORT. DUAL-POL RADAR PRECIP ESTIMATIONS APPEAR TO BE RUNNING WITHIN WITHIN 5-10% OF ACTUAL GAUGE TOTALS WITH INDICATE 0.5 TO 2.5 INCH TOTALS ARE WIDESPREAD ACROSS NEW HANOVER AND EASTERN BRUNSWICK COUNTIES. NOW THAT THIS WAVE OF STORMS IS OFFSHORE...ATTENTION TURNS TO THE NEXT UPPER DISTURBANCE CURRENTLY MOVING SOUTHEAST ACROSS THE NC/VA BORDER. THE LAST FEW HRRR RUNS STILL TRY TO CRANK OUT SCATTERED CONVECTIVE SHOWERS AND T-STORMS WITH THIS FEATURE AS IT DIPS INTO THE COASTAL PLAIN VERY LATE TONIGHT. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... A HOT AIRMASS COVERS THE CAROLINAS THIS EVENING. 850 MB TEMPS AROUND +20C USUALLY EQUATES TO UPPER 90S INLAND FROM THE COAST AND TODAY`S HOT TEMPERATURES OF 97 IN FLORENCE AND LUMBERTON WERE EXPECTED. AN UPPER LEVEL RIDGE CENTERED OVER MISSISSIPPI IS PRODUCING A NORTHWEST UPPER WIND OVER THE CAROLINAS. A SERIES OF UPPER LEVEL DISTURBANCES EMBEDDED WITHIN IN THE 20-25 KT 700-500 MB FLOW ARE PRODUCING WAVES OF SHOWERS AND THUNDERSTORMS. ONE SUCH WAVE IS APPROACHING WILMINGTON FROM THE NORTH NOW AND SHOULD BE OFF THE COAST SOUTH OF CAPE FEAR BY LATE THIS EVENING. A SECOND DISTURBANCE NOW IN SOUTHWESTERN VIRGINIA AND EASTERN KENTUCKY WILL TAKE A MORE WESTWARD TRACK...REACHING THE SC PEE DEE AND INTERSTATE 95 CORRIDOR LATE TONIGHT. THIS IS ALSO WHEN A SYNOPTIC COLD FRONT WILL BEGIN TO EASE SOUTHWARD THROUGH SOUTHEASTERN NORTH CAROLINA...REACHING NORTHEASTERN SOUTH CAROLINA BY DAYBREAK SATURDAY. THUNDERSTORMS SHOULD CONTINUE TO BUILD SOUTHWARD INTO WILMINGTON OVER THE NEXT FEW HOURS...AND POPS HAVE BEEN RAISED TO 70 PERCENT FROM BURGAW SOUTH THROUGH WILMINGTON AND WRIGHTSVILLE BEACH. THE AIRMASS IS MODERATELY UNSTABLE (CAPE AROUND 2000 J/KG) AND THERE IS ENOUGH HUMIDITY NEAR THE LCL TO ALLOW SURFACE-BASED PARCELS TO REACH THEIR LFC AND KEEP ON GOING. ACTIVITY WILL BE MUCH MORE SPARSE IN COVERAGE WESTWARD ACROSS THE SOUTH CAROLINA COASTAL PLAIN WHERE ENVIRONMENTAL RELATIVE HUMIDITY NEAR THE LCL IS ONLY 50 TO 60%. OUTSIDE OF AREAS THAT RECEIVE THUNDERSTORMS...TEMPERATURES WILL FALL QUITE SLOWLY THIS EVENING IN THE HOT AIRMASS. NEAR THE COAST DEWPOINTS IN THE MID TO UPPER 70S WILL MAINTAIN HEAT INDICES IN THE AROUND 100 THROUGH 8 PM...AND IN THE 90S UP UNTIL ALMOST MIDNIGHT. LOWS SHOULD ONLY FALL INTO MID 70S FOR MOST ARES WITH SOME UPPER 70S NEAR THE BEACHES. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/... AS OF 300 PM FRIDAY...FEATURE OF INTEREST THIS WEEKEND IS A BACK DOOR COLD FRONT WHICH WILL DROP ACROSS THE AREA FROM NE TO SW ON SATURDAY. THIS FRONT WILL BE DRIVEN BY AN AMPLIFYING 5H PATTERN...WITH A STRONG RIDGE GETTING SQUEEZED NORTH ACROSS THE MIDDLE OF THE COUNTRY BETWEEN TROUGHS ON BOTH COASTS. IT IS THIS EASTERN TROUGH DIVING SW THROUGH THE WKND THAT PUSHES THE BACK DOOR FRONT INTO...AND THROUGH...THE CWA SATURDAY. ALTHOUGH THE SURFACE FRONT CROSSES SATURDAY...STRONG CAA LAGS ABOUT 18 HRS BEHIND...AND THUS SATURDAY WILL AGAIN BE A WARM DAY LOCALLY. HOWEVER...INCREASED CLOUDINESS...LOWERED THICKNESSES...AND SHOWERS/STORMS WILL KEEP TEMPS MUCH COOLER THAN THE PAST FEW DAYS...WITH HIGHS RISING TO AROUND 90 IN THE FAR NORTH...MID 90S IN THE SOUTHERN PEE DEE. WHILE FORCING IS NOT STRONG WITH THE FRONT...AND A DIVING UPPER JET WILL ACTUALLY PUT THE REGION BENEATH THE RFQ...AN UNFAVORABLE POSITION FOR UPPER SUPPORT...STILL EXPECT CLIMO POP FOR SCT SHOWERS AND TSTMS THANKS TO PWATS NEAR 2 INCHES AND STRONG SURFACE CONVERGENCE INTO AN UNSTABLE ENVIRONMENT. ALTHOUGH COOL ADVECTION WILL BEGIN OVERNIGHT...LOWS WILL REMAIN ABOVE NORMAL...LOW 70S AREA-WIDE. COOL AND DRY ADVECTION BEGINS IN EARNEST SUNDAY MORNING...AND PWATS DROP TO LESS THAN 1 INCH...LOWEST NORTH...WITH 850MB TEMPS DROPPING 5C THROUGH THE DAY. LOTS OF LATE-AUGUST SUNSHINE WILL SOMEWHAT COUNTERACT STRONG CAA...BUT HIGHS SUNDAY WILL LIKELY BE 5-10 DEGREES COOLER THAN SATURDAY...AND IN FACT ARE EXPECTED TO BE BELOW NORMAL...LOW 80S FAR NORTH TO UPR 80S IN THE SOUTH. A FEW SHOWERS ARE POSSIBLE...ESPECIALLY EARLY IN THE DAY ACROSS THE SC ZONES CLOSER TO THE FRONT...BUT ACTIVITY WILL NOT BE WIDESPREAD OR STRONG. MUCH COOLER MINS SUNDAY NIGHT WITH MID 60S EXPECTED FAR NORTH IN THE DRY COLUMN...UPPER 60S NEAR THE SOUTH SANTEE RIVER AND ON THE BEACHES. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 300 PM FRIDAY...THE EXTENDED FORECAST WILL GENERALLY BE DRY AND SEASONABLE AS A MID LEVEL RIDGE INITIALLY OVER THE MISSISSIPPI VALLEY SHIFTS TO MORE OF A SOUTHERN POSITION BY THE END OF THE PERIOD. AT THE SURFACE...HIGH PRESSURE WILL WEDGE DOWN THE EAST COAST AND EXTEND DOWN INTO GEORGIA FOR MONDAY THROUGH WEDNESDAY. BEYOND THIS...THE FEATURE BREAKS DOWN LEAVING A WEAK PATTERN AT THE SURFACE AND ISOLATED SHOWERS AND THUNDERSTORMS MAKE AN APPEARANCE IN THE FORECAST. THE CHANCES WILL NOT BE GOOD UNTIL FRIDAY WHEN ANOTHER FRONT DROPS INTO THE REGION PROVIDING A BETTER FOCUS. TEMPERATURES WILL BE SLIGHTLY BELOW CLIMATOLOGY MONDAY THROUGH WEDNESDAY WITH THE AXIS OF SURFACE HIGH PRESSURE PROVIDING A COOL NORTHEAST FLOW. THURSDAY AND FRIDAY SEE MODERATING VALUES CLOSER TO OR EVEN A BIT ABOVE NORMAL. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 06Z...KILM IS THE COOL SPOT ACROSS THE CWA TONIGHT THANKS TO THE EARLIER TORRENTIAL RAINFALL. HAVE INCLUDED TEMPO MVFR VSBYS FOR KILM IN THE EARLY MORNING HOURS...BUT INCREASING MID/HIGH CLOUDS OVERNIGHT SHOULD AGAIN LOWER THE FOG THREAT. DESPITE DEWPOINTS IN THE UPPER 70S AT KCRE/KMYR...SFC WINDS WILL LIKELY INHIBIT BR FORMATION AT THESE TERMS. CONVECTION OVER CENTRAL NC ASSOCIATED WITH ANOTHER UPPER DISTURBANCE IS MOVING TOWARD OUR AREA...BUT THE HRRR TENDS TO WEAKEN THE ACTIVITY AS IT NEARS THE CWA. THEREFORE WILL NOT MENTION VCSH DURING THE OVERNIGHT HOURS. A COLD FRONT WILL DROP SOUTHWARD ACROSS NC THIS MORNING... APPROACHING KLBT/KILM AROUND 12Z. MODELS SUGGEST THE FRONT MAY GET HUNG UP ACROSS OUR CWA DURING THE DAY BEFORE CLEARING THE CAROLINAS LATER IN THE PERIOD. WE COULD SEE SOME SHOWERS ACROSS OUR NORTHERN ZONES THIS MORNING...BUT CONFIDENCE IS FAIRLY LOW. BETTER CHANCES FOR CONVECTION WILL BE THIS AFTN WITH THE FRONT LINGERING OVER THE AREA...ENHANCED BY SEA BREEZE AND BOUNDARY COLLISIONS. HAVE INCLUDED VCSH FOR ALL TERMS AFTER 18Z. LIGHT/VRBL WINDS IN THE EARLY MORNING WILL BECOME NORTH AND THEN NORTHEAST BEHIND THE FRONT...REMAINING BELOW 10 KT. KCRE/KMYR WILL LIKELY SEE E-SE WINDS IN THE AFTN BEHIND THE SEA BREEZE BEFORE THE FRONT PASSES THROUGH. EXTENDED OUTLOOK...MVFR/IFR CIGS/VSBYS POSSIBLE ON SUN MORNING. OTHERWISE EXPECT VFR TO PREVAIL SUN THROUGH WED AS HIGH PRESSURE RIDGES OVER THE EAST COAST IN THE WAKE OF A COLD FRONT. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1:40 AM SATURDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. RELEVANT PORTION OF PREVIOUS DISCUSSION FOLLOWS BELOW: ISOLATED SHOWERS AND T-STORMS COULD DEVELOP LATER TONIGHT AS A SECOND UPPER LEVEL DISTURBANCE APPROACHES FROM THE NORTH. A COLD FRONT ACROSS NORTH-CENTRAL NORTH CAROLINA WILL SINK SOUTHWARD OVERNIGHT...REACHING AS FAR SOUTH AS MYRTLE BEACH BY DAYBREAK SATURDAY. UNTIL THEN...SOUTHWEST WINDS 10-15 KNOTS ARE EXPECTED ALONG WITH 2 FOOT SEAS...EVENLY SPLIT BETWEEN A SOUTHEASTERLY SWELL AND A SOUTHWEST WIND CHOP. SCATTERED THUNDERSTORMS AHEAD OF THE FRONT WILL BE MOST NUMEROUS THIS EVENING IN THE CAPE FEAR-AREA WATERS. ANY STORMS WILL BE CAPABLE OF PRODUCING GUSTY OUTFLOW WINDS AND PLENTY OF LIGHTNING. ALTHOUGH COVERAGE WILL DIMINISH OVERNIGHT THE CHANCES OF ADDITIONAL POP-UP STORMS WILL CONTINUE THROUGH DAYBREAK...SHIFTING SOUTHWARD TO THE SOUTH CAROLINA WATERS WITH THE FRONT. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 300 PM FRIDAY...BACK DOOR COLD FRONT WILL DROP ACROSS THE WATERS FROM NE TO SW DURING SATURDAY...CAUSING A WIND SHIFT TO THE N/NE BEHIND THIS BOUNDARY. WIND SHIFT WILL OCCUR FIRST ACROSS THE FAR NORTHERN LEGS OFF THE CAPE FEAR COAST...WITH WINDS BECOMING N THEN NE SATURDAY MORNING...WITH THE WATERS OFF GEORGETOWN COUNTY NOT EXPERIENCING THE WIND SHIFT UNTIL SATURDAY NIGHT. THE GRADIENT REMAINS RELAXED SATURDAY...SO WIND SPEEDS THROUGH THIS FRONTAL PASSAGE WILL BE 5-10 KTS REGARDLESS OF DIRECTION. VERY LATE SATURDAY NIGHT AND ESPECIALLY ON SUNDAY...A NE SURGE OCCURS AND WINDS QUICKLY RISE TO 15-25 KTS ACROSS THE WATERS. SEAS THROUGH THE WKND WILL BE PRIMARILY WIND DRIVEN...RISING FROM 2-3 FT SATURDAY...TO 4-6 FT ON SUNDAY...AND A SMALL CRAFT ADVISORY MAY BE NEEDED. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 300 PM FRIDAY...EXPECT NORTHEAST WINDS THROUGH THE PERIOD COURTESY OF HIGH PRESSURE ALIGNED ALONG THE EASTERN SEABOARD. WIND SPEEDS WILL BE 15-20 KNOTS MONDAY INTO MIDDAY TUESDAY RETREATING FROM THAT POINT ON TO SINGLE DIGITS BY LATER WEDNESDAY. LOWER CONFIDENCE IN SEAS AS THE SPECTRUM IS HIGHLY DEPENDENT ON HOW INVEST AL96 DOES. CURRENTLY THERE IS A FEW SIX FOOTERS ACROSS THE OUTER WATERS OF AMZ252 BUT OTHERWISE THE SEAS ARE 3-5 FEET. IF THE SYSTEM DEVELOPS MORE THAN ANTICIPATED THE SWELL ADDED TO THE SPECTRUM COULD INCREASE THE SIGNIFICANT SEAS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...JDW NEAR TERM...REK/TRA SHORT TERM...JDW LONG TERM...SHK AVIATION...BJR MARINE...REK/TRA/JDW/SHK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
259 PM CDT SAT AUG 23 2014 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 300 PM CDT SAT AUG 23 2014 THE MAIN FORECAST ISSUE IN THE SHORT TERM PERIOD WILL BE HEAVY RAIN LATE THIS AFTERNOON AND THIS EVENING. THEN ENDING ACROSS THE SOUTH LATE THIS EVENING BUT CONTINUING ACROSS THE NORTH INTO SUNDAY. LATEST RADAR ESTIMATES HAVE MATCHED UP WELL WITH OBSERVED REPORTS ACROSS SOUTHWEST NORTH DAKOTA. GENERALLY 1 TO 1.5 INCHES REPORTED SOUTH AND WEST OF A LINE FROM SELFRIDGE TO THEODORE ROOSEVELT NP. DID GET A REPORT FROM WFO BILLINGS OF CLOSER TO 5 INCHES NEAR BAKER MT. AS OF YET CALLS TO SPOTTERS AND BOWMAN EM HAVE RESULTED IN NO SIGNIFICANT FLOODING ISSUES. HOWEVER...WE HAVE ISSUED AN AREAL FLOOD ADVISORY SOUTH AND WEST OF LAKE SAKAKAWEA AND THE MISSOURI RIVER...TO COVER THE 1 TO 1.5 INCHES OF RAIN THAT HAS FALLEN IN ADDITION TO ADDITIONAL EXPECTED RAIN THROUGH THE AFTERNOON AND TONIGHT. REGARDING THE CURRENT FLOOD WATCH AND POTENTIAL OF SEVERE WEATHER... WILL LET THE WATCH CONTINUE. HEAVIEST RAIN HAS FALLEN ACROSS THE MOST SATURATED SOILS IN THE SOUTHWEST. THE HEAVIEST ADDITIONAL ACCUMULATIONS TONIGHT SHOULD BE CENTERED ACROSS THE NORTH CENTRAL AND NORTHWEST. IF WE HAD TO PARE IT DOWN...WOULD PROBABLY REMOVE WELLS SOUTH THROUGH MCINTOSH. HOWEVER...THERE IS STILL A THREAT OF AFTERNOON AND EVENING CONVECTION HERE AS THE SURFACE LOW LIFTS INTO NORTH DAKOTA. THUS WILL CONTINUE AS IS FOR NOW. THE LATEST HRRR STILL DEVELOPS SCATTERED CONVECTION IN THIS AREA THIS EVENING. HOWEVER THE STRONGEST CONVECTION IS NOW BEING PLACED TO THE SOUTH OF THE CWA. WITH OUR EAST TO NORTHEAST FLOW AND COOLER TEMPERATURES OVER NORTH DAKOTA THIS SEEMS REASONABLE...BUT WITH THE SURFACE LOW LIFTING INTO CENTRAL NORTH DAKOTA THINK OUR SOUTHEAST CWA WILL BE IN A FAVORED LOCATION FOR ABUNDANT LOW LEVEL HELICITY THUS WILL CONTINUE A MENTION OF SEVERE OVER THE SOUTHEAST CWA. WE DRY OUT FROM SOUTH TO NORTH LATE THIS EVENING THROUGH SUNDAY. HIGHEST POPS WILL REMAIN OVER THE NORTHWEST AND FAR NORTH CENTRAL. WITH THE UPPER LEVEL SLOW LIFTING THROUGH EASTERN MONTANA INTO NORTHWEST ND...THERE SHOULD STILL BE ENOUGH MID TO UPPER LEVEL FORCING TO MENTION ISOLATED THUNDER THROUGH THE DAY WHEREVER WE HAVE A MENTION OF SHOWERS. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 300 PM CDT SAT AUG 23 2014 SUNDAY EVENING THE UPPER LEVEL LOW IS PROGGED TO BE AT THE BORDER OF MONTANA AND NORTH DAKOTA...WITH THE SURFACE LOW ALONG THE NORTH DAKOTA/CANADIAN/MINNESOTA BORDER. THE ELONGATED SURFACE LOW/FRONT COMBINED WITH THE UPPER LOW TO THE WEST WILL KEEP HIGH CHANCES OF SHOWERS IN THE NORTHWEST/NORTH CENTRAL SUNDAY NIGHT. THE SYSTEM LIFTS NORTHEASTWARD SUNDAY NIGHT AND INTO MONDAY...WITH COLD ADVECTION IN ITS WAKE. LOOKING AT LOWS SUNDAY NIGHT IN THE 40S WEST TO LOWER 50S IN THE JAMES VALLEY. MOSTLY CLOUDY SKIES NORTH MONDAY WILL KEEP MAXIMUM TEMPERATURES CONFINED TO THE UPPER 50S WITH 60S SOUTH. BY TUESDAY MORNING THE SURFACE HIGH SETTLES OVER NORTH DAKOTA...AND LOW TEMPERATURES SHOULD BE IN THE 40S ACROSS WESTERN AND CENTRAL NORTH DAKOTA. DURING THE DAY TUESDAY THROUGH WEDNESDAY THE TRAILING UPPER LEVEL TROUGH MOVES EAST ACROSS THE NORTHERN PLAINS...WITH ISOLATED TO SCATTERED SHOWERS POSSIBLE. MINOR UPPER LEVEL RIDGING OCCURS WEDNESDAY NIGHT THROUGH FRIDAY. THE APPROACH OF ANOTHER ROCKIES TROUGH TOWARDS NEXT WEEKEND MAY BE THE NEXT CHANCE OF SHOWERS AND THUNDERSTORMS. A SLOW WARMING TREND WITH HIGHS TUESDAY IN THE 60S WARMING TO THE 80S BY FRIDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 300 PM CDT SAT AUG 23 2014 MAINLY IFR CEILINGS EXPECTED THROUGH THE FORECAST PERIOD WITH OCCASIONAL MVFR VISIBILITIES IN HEAVIER SHOWERS. COULD SEE PERIODS OF MVFR CEILINGS THIS AFTERNOON...THEN AGAIN LATE SUNDAY MORNING AS THE STRONG LOW LIFTS OUT OF THE AREA. OTHERWISE EXPECT IFR TO OCCASIONALLY LIFR. WINDS WILL BE VARIABLE WITH THE SURFACE LOW EXPECTED TO LIFT THROUGH WESTERN NORTH DAKOTA...BUT MAINLY EAST TO SOUTHEAST TODAY AND THIS EVENING...SHIFTING WESTERLY FROM SOUTH TO NORTH ON SUNDAY. SPEEDS GENERALLY 10 TO 25 KNOTS. && .HYDROLOGY... ISSUED AT 300 PM CDT SAT AUG 23 2014 MODERATE TO HEAVY RAINS OVER THE PAST WEEK HAVE KEPT SOIL MOISTURE ABNORMALLY HIGH ACROSS WESTERN AND CENTRAL NORTH DAKOTA. RAINFALL THAT OCCURRED TODAY...ALONG WITH THE EXPECTED RAINFALL INTO TONIGHT MAY LIKELY LEAD TO SOME OVERLAND FLOODING...ALONG WITH INCREASED FLOWS INTO CREEKS...STREAMS...AND RIVERS. ALONG WITH THE FLOOD WATCH THAT WAS ISSUED ON FRIDAY FOR TODAY THROUGH SUNDAY...HAVE ALSO ISSUED AN AREAL FLOOD ADVISORY FOR THE AREA SOUTH AND WEST OF THE MISSOURI RIVER. RADAR ESTIMATES WERE IN AGREEMENT WITH SOME RAINFALL REPORTS OF 1 TO 1.5 INCHES OF RAINFALL SO FAR TODAY. IN ADDITION...WHILE THERE IS NO REASONABLE EXPECTATION OF MAJOR RIVER FLOODING...AT A MINIMUM THERE WILL BE SIGNIFICANT WITHIN BANK RISES...AND MINOR RIVER FLOODING CANNOT BE RULED OUT. .BIS WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR NDZ001>005-009>013- 017>023-031>036-040>047-050. && $$ SHORT TERM...TWH LONG TERM...JV AVIATION...TWH
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
220 PM EDT SAT AUG 23 2014 .SYNOPSIS... UPPER RIDGING WILL SLOWLY BUILD OVER THE REGION BY SUNDAY...BRINGING AN END TO THE RECENT SIEGE OF SHOWER AND THUNDERSTORM ACTIVITY. THE UPPER RIDGE WILL DOMINATE THE WEATHER PATTERN OVER THE NORTHEAST UNITED STATES AND SOUTHEASTERN CANADA DURING THE EARLY AND MIDDLE PART OF THE UPCOMING WEEK...WITH THE NEXT CHANCE OF RAINFALL NOT ARRIVING UNTIL LATE WEDNESDAY OR THURSDAY FROM AN APPROACHING MIDWESTERN FRONTAL SYSTEM. && .NEAR TERM /THROUGH TONIGHT/... SATELLITE SHOWS SOME BREAKS IN THE OVERCAST OVER THE FAR WESTERN PERIPHERY OF MY FCST AREA...WHICH IS WHERE WE ARE MANAGING TO DEVELOP SOME CAPE. WITH THE PERSISTENT LOW LEVEL CONVERGENCE AND EASTERLY UPSLOPE FLOW...SCATTERED CONVECTION IS BEGINNING TO POP IN THIS SLIGHTLY ELEVATED INSTABILITY FROM MCKEAN COUNTY DOWN THROUGH WESTERN CAMBRIA AND SOMERSET COUNTIES. LATEST HRRR DOESN`T SHOW ANY PARTICULAR AREA FAVORING ANY KIND OF REAL ORGANIZATION OF THE CONVECTION INTO THE LATE AFTERNOON HOURS...BUT WE HAVE SEEN SOME OF THE SHOWERS BE VERY EFFICIENT...PRODUCING LOCALLY HEAVY RAINS. THE PERSISTENT...AND ANOMALOUS SFC-850 MB EAST TO SERLY FLOW AND HIGH PWAT AIR WILL AT LEAST MAINTAIN WIDESPREAD/THICK CLOUD COVER AND UNSEASONABLY COOL TEMPS...EXCEPT OVER THOSE FAR WESTERN AREAS WHERE A BIT OF SUNSHINE WILL HELP PUSH TEMPS INTO THE LOWER TO MID 70S. THE LARGE SCALE PATTERN IS ADVERTISED TO CHANGE ONLY SLOWLY OVER THE NEXT 12-18 HOURS...WITH DRIER AIR EVENTUALLY SLIDING DOWN OUT OF THE NORTH AND SHOVING THE HIGHER MOISTURE BACK TO OUR SOUTH AND WEST. MOSTLY CLOUDY SKIES WILL PERSIST FOR MUCH OR PERHAPS ALL OF THE OVERNIGHT WITH A CHANCE OF LIGHT RAIN OR DRIZZLE MAINLY BEFORE MIDNIGHT...AND ACROSS THE SW CORNER OF THE CWA. ANY CLEARING LATE TONIGHT WILL COMBINE WITH THE MOIST GROUND AND LIGHT WIND TO PRODUCE AREAS OF FOG...THAT WILL BECOME LOCALLY DENSE AFTER MIDNIGHT. LOW TEMPS EARLY SUNDAY WILL RANGE FROM THE MID 50S ACROSS THE NORTH...TO AROUND 60F IN THE SOUTHERN VALLEYS. && .SHORT TERM /SUNDAY/... DRIER AIR WILL SETTLE OVER THE AREA SUNDAY BRINGING A MUCH ANTICIPATED BREAK FROM THE RECENT ALMOST DAILY ASSAULT OF SHOWERS AND THUNDERSTORMS. CANNOT RULE OUT A LINGERING SHOWER OR DRIZZLE OVER THE SWRN AREAS IN THE AREA OF BEST LOW LEVEL UPSLOPE FLOW...BUT OVERALL TREND WILL BE FOR MOST LOCATIONS TO SEE A RAIN-FREE DAY FOR A CHANGE. AREAS OF MORNING CLOUDS AND PERHAPS SOME PATCHY LIGHT DRIZZLE... WILL TRANSITION INTO INCREASINGLY SUNNY SKIES DURING THE MIDDAY AND AFTERNOON HOURS SUNDAY. TEMPS SUNDAY WILL REBOUND NICELY FROM SATURDAY/S CHILL WITH AFTERNOON HIGHS IN THE MID 70S ACROSS THE MTNS...AND AROUND 80F THROUGHOUT THE SUSQ VALLEY. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... MUCH OF THE EXTENDED WILL FEATURE A BIG RIDGE DOMINATING THE PATTERN OVER THE EASTERN AND NORTHEASTERN US. FAIR WEATHER WILL DEVELOP ALONG WITH WARMING TEMPERATURES AS THE RIDGE ESTABLISHES ITSELF AND MAINTAINS ITS HOLD UNTIL AT LEAST LATER WEDNESDAY-THURSDAY WHEN THE NEXT FRONTAL SYSTEM IS ADVERTISED TO APPROACH. 500 HEIGHTS IN EXCESS OF 5900M ARE FCST TO POKE INTO PA BY LATER MONDAY AND CONTINUE INTO WED. THIS WILL ASSURE THE FIRST DAYS OF THE NEW SCHOOL YEAR WILL BE WARM AND FAIRLY UNCOMFORTABLE. THE OPERATIONAL GFS AND ECMWF KEEP US DRY THROUGH AT LEAST LATER WEDNESDAY WHILE THE GEFS CONTINUES THE TREND TOWARD BEING MORE PESSIMISTIC...BRINGING MEASURABLE RAINS EAST QUICKER UNDER A FLATTER UPPER FLOW. IT SEEMS THE RESOLUTION OF THE TROPICAL SYSTEM IS PLAYING A ROLE IN THE EXTENDED FORECASTS FOR THE GFS/GEFS VS THE ECMWF. THE ECMWF HUSTLES A TROPICAL STORM OFF THE EAST COAST FASTER THAN THE GFS...WHICH ALLOWS IT TO REBUILD THE EASTERN RIDGE QUICKER. STILL TOO MUCH UNCERTAINTY TO LATCH ONTO ANY SOLID SOLUTION. WILL KEEP THE CURRENT BLAND CHANCE OF SHOWERS STARTING WEDNESDAY NIGHT LASTING INTO AT LEAST THURSDAY NIGHT. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... STILL HAVE LOW CIGS ACROSS THE AREA AND NOT MUCH CHANGES EXPECTED THIS AFTERNOON. WIDELY SCATTERED SHOWER ACTIVITY ACROSS THE ENTIRE AREA. FOG AND CEILING RESTRICTIONS WILL AGAIN OVERSPREAD THE AREA TONIGHT. IN THE LONGER RUN...HIGH PRESSURE WILL SLOWLY BUILD INTO THE NORTHEAST ON SUNDAY CONTINUING INTO MID WEEK. FRONT APPROACHING LATER WEDNESDAY AND THURSDAY MAY BRING THE NEXT ROUND OF SHRA/TSRA. OUTLOOK... SUN...LOW CIGS AND FOG EARLY...THEN VFR MON- WED...MORNING RESTRICTIONS FROM FOG POSSIBLE...OTHERWISE VFR. THU...RESTRICTIONS POSSIBLE WITH THUNDERSTORMS AND A COLD FRONT. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE NEAR TERM...LA CORTE SHORT TERM...LA CORTE LONG TERM...LA CORTE AVIATION...JUNG/ROSS
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
902 PM CDT SUN AUG 24 2014 .DISCUSSION... SKIES ARE MOSTLY CLEAR OVER MUCH OF THE FORECAST AREA THIS EVENING WITH TEMPERATURES RANGING FROM THE LOWER 70S TO MID 80S. ALL OF THE THUNDERSTORM ACTIVITY THAT WAS OVER THE FORECAST AREA EARLIER THIS EVENING HAS ENDED AND NO ADDITIONAL THUNDERSTORMS ARE EXPECTED FOR THE REMAINDER OF TONIGHT. WILL UPDATE FORECAST TO REMOVE ANY MENTION OF RAIN TONIGHT. ARS && .PREV DISCUSSION... /ISSUED 615 PM CDT SUN AUG 24 2014/ UPDATE... UPDATED TO EXTEND AFTERNOON RAIN CHANCES TO WEST OF THE MS RIVER. DISCUSSION... NQA RADAR BACK IN SERVICE AND JUST IN TIME TO SHOW CONVECTION DEVELOPING IN NORTH MISSISSIPPI. TEMPERATURES WERE MAINLY IN THE 90S ACROSS THE MIDSOUTH WITH A RECORD 100 DEGREES...THE WARMEST READING SINCE AUGUST 2012...AT THE MEMPHIS INTERNATIONAL AIRPORT. FOR THE REMAINDER OF TODAY AND TONIGHT...SHORT TERM HRRR MODEL SHOWING CONVECTION BECOMING SCATTERED BY 4 PM FOR POINTS ALONG AND WEST OF THE MISSISSIPPI RIVER...WHICH CURRENTLY LINES UP WITH PW`S ABOVE 1.80 INCHES. COULDN`T RULE OUT AN ISOLATED WET MICROBURST WITH THE STRONGEST STORMS. ACTIVITY WILL WANE BY 9 PM LEAVING SKIES PARTLY CLOUDY OVERNIGHT. THIS SHOULD HELP KEEP MORE HEAT IN...WITH OVERNIGHT LOWS AGAIN IN THE MID AND UPPER 70S. MONDAY AND TUESDAY...A WEAK DISTURBANCE WILL MOVE WESTWARD ALONG THE GULF COAST/SOUTHSIDE OF THE UPPER RIDGE...AND AS IT DOES EASTERLY WINDS IN THE BOUNDARY LAYER AND MIDLEVELS WILL SLIDE DRIER AIR OFF THE APPALACHIANS IN ITS WAKE. HEAT INDICES WILL CONTINUE TO FLIRT WITH 105F TOMORROW...DESPITE MORE CLOUD COVER AND CONVECTION. FEEL BY TUESDAY ENOUGH DRY AIR WILL HAVE OVERSPREAD THE MIDSOUTH TO REDUCE HEAT INDICES BELOW 105F. ISOLATED STORMS WILL BE POSSIBLE ON TUESDAY BUT MAINLY WEST OF THE MISSISSIPPI RIVER NEAR THE FRONT EDGE OF THE DRIER AIR. WEDNESDAY THROUGH FRIDAY...MODELS ARE IN GOOD AGREEMENT THAT THE UPPER RIDGE WILL REMAIN OVER THE REGION...BUT STRONGER SUBSIDENCE WILL KEEP DEWPOINTS IN THE 60S AND LOWER RAIN CHANCES TO AROUND 10 PERCENT. TEMPERATURES WILL BE IN THE LOW TO MID 90S WITH AFTERNOON HEAT INDICES IN THE 93-100F RANGE. NEXT WEEKEND...THE GFS AND EURO ARE BECOMING BETTER ALIGNED THAT THE RIDGE WILL FLATTEN IN RESPONSE TO AN APPROACHING CENTRAL PLAINS SHORTWAVE. THIS DISTURBANCE NOW APPEARS SOMEWHAT WEAKER AND OUT OF PHASE WITH THE MAIN UPPER LEVEL FLOW. NONETHELESS MOISTURE OUT AHEAD OF THE SYSTEM WILL MOVE OVER THE OZARKS ON SATURDAY AND INTO THE MIDSOUTH BY EARLY SUNDAY. HAVE BUMPED UP TEMPERATURES TO MAINLY THE LOW 90S FOR HIGHS AND KEPT A CONSERVATIVE APPROACH TO THE RAIN CHANCES. JAB && .AVIATION... 00Z TAF CYCLE (25/00Z-26/00Z) LINGERING TSRA ARE EXPECTED TO DISSIPATE THIS EVENING AROUND 01Z. ISOLATED TO SCATTERED TSRA ARE EXPECTED TO DEVELOP MONDAY AFTERNOON AROUND THE KMEM...KMKL...AND KTUP TAF SITES...MENTIONED VCTS FOR THESE SITES. OTHERWISE VFR CONDITIONS WILL PREVAIL DURING THE PERIOD...THE EXCEPTION POSSIBLY BEING MVFR CONDITIONS IN FOG AT KMKL EARLY MONDAY MORNING. WINDS LIGHT AND VARIABLE TONIGHT. WINDS MONDAY E-SE 4-6 KTS. JCL && .MEG WATCHES/WARNINGS/ADVISORIES... AR...HEAT ADVISORY UNTIL 7 PM CDT MONDAY FOR CLAY-CRAIGHEAD- CRITTENDEN-CROSS-GREENE-LAWRENCE-LEE AR-MISSISSIPPI- PHILLIPS-POINSETT-RANDOLPH-ST. FRANCIS. MO...HEAT ADVISORY UNTIL 7 PM CDT MONDAY FOR DUNKLIN-PEMISCOT. MS...HEAT ADVISORY UNTIL 7 PM CDT MONDAY FOR ALCORN-BENTON MS-CALHOUN- CHICKASAW-COAHOMA-DESOTO-ITAWAMBA-LAFAYETTE-LEE MS-MARSHALL- MONROE-PANOLA-PONTOTOC-PRENTISS-QUITMAN-TALLAHATCHIE-TATE- TIPPAH-TISHOMINGO-TUNICA-UNION-YALOBUSHA. TN...HEAT ADVISORY UNTIL 7 PM CDT MONDAY FOR BENTON TN-CARROLL- CHESTER-CROCKETT-DECATUR-DYER-FAYETTE-GIBSON-HARDEMAN- HARDIN-HAYWOOD-HENDERSON-HENRY-LAKE-LAUDERDALE-MADISON- MCNAIRY-OBION-SHELBY-TIPTON-WEAKLEY. && $$
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
617 PM CDT SUN AUG 24 2014 .UPDATE...ADDED AVIATION SECTION FOR 00Z TAF`S. && .AVIATION...BNA/CKV/CSV...SURFACE RIDGE IS SITUATED DIRECTLY OVER MIDDLE TENNESSEE THIS EVENING, WITH VERY LITTLE ACTIVITY OCCURRING ACROSS THE MID STATE AT THIS TIME. HRRR SUGGESTS THAT WE CAN EXPECT NOTHING OVERNIGHT, ALTHOUGH LOOK FOR RADIATION FOG TO DEVELOP AT CKV AND CSV AFTER 06Z. RIDGE WILL SHIFT TO OUR EAST TOMORROW AFTERNOON, WITH VERY LIGHT WINDS THE NEXT 24 HRS. ISOLATED STORMS ARE POSSIBLE MONDAY AFTERNOON, AND WILL ADDRESS THIS WITH VCTS/CB REMARKS FOR NOW. && .PREV DISCUSSION... /ISSUED 243 PM CDT SUN AUG 24 2014/ DISCUSSION... LAST NIGHT/S WIDE SPREAD RAINFALL AND THIS MORNING/S LEFTOVER CLOUDS AND SHOWERS HELPED KEEP 19Z TEMPERATURES 5 TO 10 DEGREES LOWER THAN 24 HOURS AGO...ESPECIALLY ON THE PLATEAU WHERE THICKEST CLOUDS CONTINUED. HEAT ADVISORY FOR THE WESTERN 2/3 OF MIDDLE TN EXPIRES AT 02Z TONIGHT BUT MAY CANCEL IT EARLY DEPENDING ON 20Z AND 21Z HEAT INDEX VALUES. THE LOWER TEMPS ARE HELPING DELAY TSRA DEVELOPMENT SO FAR TODAY. STILL EXPECT SOME STORMS TO FORM LATER THIS AFTERNOON INTO THIS EVENING BUT POPS MAINLY IN THE SLIGHT CHANCE RANGE. ANY STORMS SHOULD DRIFT SLOWLY SOUTHWESTWARD. STORM POTENTIAL SHOULD DECREASE BY MIDNIGHT. PATCHY FOG HAS OCCURRED THE PAST FEW MORNINGS AND EXPECT A REPEAT LATE TONIGHT AND EARLY MONDAY...MAINLY BY BODIES OF WATER. WEATHER PATTERN FOR THE WEEK AHEAD... THE HIGH AMPLITUDE H5 RIDGE AXIS WAS STILL OVER THE MS RIVER VALLEY TODAY. THE RIDGE WILL FLATTEN AND WEAKEN SOMEWHAT OVER THE NEXT FEW DAYS AS A STRONG TROF MOVES EASTWARD ACROSS THE NORTHERN U.S. AND SOUTHERN CANADA. THUS...TODAY/S LIGHT NORTHEASTERLY H5 FLOW WILL BECOME EASTERLY ON MONDAY AND THEN LIGHT/VARIABLE TUESDAY AND WEDNESDAY WHEN THE RIDGE AXIS IS ORIENTED ALONG LENGTH OF TN. BY LATE IN THE WEEK... THE SLIGHTLY WEAKENED H5 RIDGE WILL MOVE OVER THE SOUTHEASTERN U.S. BEFORE POSSIBLY YIELDING TO A WEAK TROF NEXT WEEKEND. THE DETAILS FOR THE WEEK AHEAD... LOW POPS WARRANTED MONDAY MAINLY ACROSS THE SOUTH AND THE HIGHER TERRAIN OF THE EAST WHERE MODELS FORECAST DEEPER MOISTURE. DO NOT EXPECT ANY SIGNIFICANT RAIN TUESDAY OR WEDNESDAY AS H5 RIDGE AXIS SITS OVER THE STATE. RAIN CHANCES WILL REAPPEAR ON THURSDAY WITH THE POTENTIAL FOR A WEAK BACK DOOR FRONT TO APPROACH AS A SFC HIGH BUILDS TO OUR NORTHEAST IN THE WAKE OF THE PASSING CANADIAN H5 TROF. SLIGHT CHANCE POPS WILL CONTINUE FRIDAY THROUGH NEXT WEEKEND AS H5 RIDGE SLIDES OVER SOUTHEAST STATES AND A WEAK H5 TROF APPROACHES FROM THE WEST. TEMPERATURES WILL STAY ABOVE AVERAGE ALL WEEK WITH MAXES OF 90 TO 95 MOST AREAS. MAX TEMPS COULD START EDGING DOWNWARD A TAD NEXT WEEKEND AS THE H5 RIDGE WEAKENS AND THE TROF APPROACHES...BUT WE SHOULD STILL REMAIN ABOVE SEASONAL NORMS. FYI...THE AVERAGE HIGH IN NASHVILLE IN LATE AUGUST IS 86 DEGREES. && .OHX WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR TNZ005>009-023>030- 056>064-075-077-093>095. && $$ ROSE
AREA FORECAST DISCUSSION...UPDATED
NWS MEMPHIS TN
615 PM CDT SUN AUG 24 2014 .DISCUSSION... UPDATED TO INCLUDE THE 00Z AVIATION DISCUSSION BELOW. JCL && .PREV DISCUSSION... /ISSUED 333 PM CDT SUN AUG 24 2014/ UPDATE... UPDATED TO EXTEND AFTERNOON RAIN CHANCES TO WEST OF THE MS RIVER. DISCUSSION... NQA RADAR BACK IN SERVICE AND JUST IN TIME TO SHOW CONVECTION DEVELOPING IN NORTH MISSISSIPPI. TEMPERATURES WERE MAINLY IN THE 90S ACROSS THE MIDSOUTH WITH A RECORD 100 DEGREES...THE WARMEST READING SINCE AUGUST 2012...AT THE MEMPHIS INTERNATIONAL AIRPORT. FOR THE REMAINDER OF TODAY AND TONIGHT...SHORT TERM HRRR MODEL SHOWING CONVECTION BECOMING SCATTERED BY 4 PM FOR POINTS ALONG AND WEST OF THE MISSISSIPPI RIVER...WHICH CURRENTLY LINES UP WITH PW`S ABOVE 1.80 INCHES. COULDN`T RULE OUT AN ISOLATED WET MICROBURST WITH THE STRONGEST STORMS. ACTIVITY WILL WANE BY 9 PM LEAVING SKIES PARTLY CLOUDY OVERNIGHT. THIS SHOULD HELP KEEP MORE HEAT IN...WITH OVERNIGHT LOWS AGAIN IN THE MID AND UPPER 70S. MONDAY AND TUESDAY...A WEAK DISTURBANCE WILL MOVE WESTWARD ALONG THE GULF COAST/SOUTHSIDE OF THE UPPER RIDGE...AND AS IT DOES EASTERLY WINDS IN THE BOUNDARY LAYER AND MIDLEVELS WILL SLIDE DRIER AIR OFF THE APPALACHIANS IN ITS WAKE. HEAT INDICES WILL CONTINUE TO FLIRT WITH 105F TOMORROW...DESPITE MORE CLOUD COVER AND CONVECTION. FEEL BY TUESDAY ENOUGH DRY AIR WILL HAVE OVERSPREAD THE MIDSOUTH TO REDUCE HEAT INDICES BELOW 105F. ISOLATED STORMS WILL BE POSSIBLE ON TUESDAY BUT MAINLY WEST OF THE MISSISSIPPI RIVER NEAR THE FRONT EDGE OF THE DRIER AIR. WEDNESDAY THROUGH FRIDAY...MODELS ARE IN GOOD AGREEMENT THAT THE UPPER RIDGE WILL REMAIN OVER THE REGION...BUT STRONGER SUBSIDENCE WILL KEEP DEWPOINTS IN THE 60S AND LOWER RAIN CHANCES TO AROUND 10 PERCENT. TEMPERATURES WILL BE IN THE LOW TO MID 90S WITH AFTERNOON HEAT INDICES IN THE 93-100F RANGE. NEXT WEEKEND...THE GFS AND EURO ARE BECOMING BETTER ALIGNED THAT THE RIDGE WILL FLATTEN IN RESPONSE TO AN APPROACHING CENTRAL PLAINS SHORTWAVE. THIS DISTURBANCE NOW APPEARS SOMEWHAT WEAKER AND OUT OF PHASE WITH THE MAIN UPPER LEVEL FLOW. NONETHELESS MOISTURE OUT AHEAD OF THE SYSTEM WILL MOVE OVER THE OZARKS ON SATURDAY AND INTO THE MIDSOUTH BY EARLY SUNDAY. HAVE BUMPED UP TEMPERATURES TO MAINLY THE LOW 90S FOR HIGHS AND KEPT A CONSERVATIVE APPROACH TO THE RAIN CHANCES. JAB && .AVIATION... 00Z TAF CYCLE (25/00Z-26/00Z) LINGERING TSRA ARE EXPECTED TO DISSIPATE THIS EVENING AROUND 01Z. ISOLATED TO SCATTERED TSRA ARE EXPECTED TO DEVELOP MONDAY AFTERNOON AROUND THE KMEM...KMKL...AND KTUP TAF SITES...MENTIONED VCTS FOR THESE SITES. OTHERWISE VFR CONDITIONS WILL PREVAIL DURING THE PERIOD...THE EXCEPTION POSSIBLY BEING MVFR CONDITIONS IN FOG AT KMKL EARLY MONDAY MORNING. WINDS LIGHT AND VARIABLE TONIGHT. WINDS MONDAY E-SE 4-6 KTS. JCL && .MEG WATCHES/WARNINGS/ADVISORIES... AR...HEAT ADVISORY UNTIL 7 PM CDT MONDAY FOR CLAY-CRAIGHEAD- CRITTENDEN-CROSS-GREENE-LAWRENCE-LEE AR-MISSISSIPPI- PHILLIPS-POINSETT-RANDOLPH-ST. FRANCIS. MO...HEAT ADVISORY UNTIL 7 PM CDT MONDAY FOR DUNKLIN-PEMISCOT. MS...HEAT ADVISORY UNTIL 7 PM CDT MONDAY FOR ALCORN-BENTON MS-CALHOUN- CHICKASAW-COAHOMA-DESOTO-ITAWAMBA-LAFAYETTE-LEE MS-MARSHALL- MONROE-PANOLA-PONTOTOC-PRENTISS-QUITMAN-TALLAHATCHIE-TATE- TIPPAH-TISHOMINGO-TUNICA-UNION-YALOBUSHA. TN...HEAT ADVISORY UNTIL 7 PM CDT MONDAY FOR BENTON TN-CARROLL- CHESTER-CROCKETT-DECATUR-DYER-FAYETTE-GIBSON-HARDEMAN- HARDIN-HAYWOOD-HENDERSON-HENRY-LAKE-LAUDERDALE-MADISON- MCNAIRY-OBION-SHELBY-TIPTON-WEAKLEY. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS LUBBOCK TX
725 PM CDT SUN AUG 24 2014 .UPDATE... QUICK UPDATE TO ADJUST POP/WX/QPF GRIDS THROUGH THIS EVENING TO BETTER CORRESPOND TO CURRENT RADAR TRENDS. MOST NOTABLY... INCREASED POPS INTO THE CHANCE AND LIKELY CATEGORIES ACROSS A GOOD PORTION OF THE ROLLING PLAINS WHERE A POORLY ORGANIZED CLUSTER OF CONVECTION CONTINUES. WE EXPECT AN OVERALL DOWNWARD TREND IN THE CONVECTION THROUGH THE MID/LATE EVENING HOURS AS THE UNSTABLY AND DIURNALLY DRIVEN FORCING WANES. && .PREV DISCUSSION... /ISSUED 636 PM CDT SUN AUG 24 2014/ AVIATION... CURRENT RADAR TRENDS SUGGEST THAT KLBB AND KCDS MAY ESCAPE ANY -TSRA IN THE NEXT HOUR OR SO...BUT THERE IS STILL AN OUTSIDE CHANCE. ALSO...SOME GUSTY OUTFLOW WINDS ARE STILL POSSIBLE. OTHERWISE...VFR CONDITIONS WITH SRLY SURFACE WINDS EXPECTED THROUGH MID-AFTERNOON MONDAY. PREV DISCUSSION... /ISSUED 343 PM CDT SUN AUG 24 2014/ SHORT TERM... DESPITE OF A WESTWARD EXPANSION OF WEAK RIDGING ALOFT AND VERY LITTLE IF ANY SURFACE FEATURES...AN ADEQUATE BOOST IN THETA-E EARLIER TODAY SUPPLIED MUCH OF THE AREA WITH DEEPER MOISTURE NECESSARY FOR SOME DIURNALLY DRIVEN TSTORMS. NON-HIGH RES MODELS HAVE LARGELY MISSED THE BOAT SO FAR TODAY WITH THE EXPERIMENTAL MODELS PLAYING THE ROLE OF THE DARK HORSE. RAP DATA SHOW THE RICHEST PWATS OF 1.3 INCHES CONFINED EAST OF A BROWNFIELD TO SILVERTON LINE WITH GENERALLY ONE INCH OR LESS FARTHER WEST. ENVIRONMENT IN THE RICHER PWATS IS CHARACTERIZED BY SBCAPES OF 1200-2500 J/KG WITH WEAK SHEAR. THIS THEME WILL PERSIST THROUGH MID-EVENING AT WHICH POINT TSTORMS WILL DWINDLE...BUT UNTIL THEN WE EXPECT ADDITIONAL STRONG TO PERHAPS BRIEFLY SEVERE PULSE MODES WITH MICROBURSTS THE PRIMARY HAZARD. BY MONDAY MORNING...DEEPER MONSOONAL MOISTURE WILL BE TUGGED NORTH INTO NEW MEXICO AROUND THE ZONAL RIDGE AXIS STILL POISED FIRMLY OVER THE SOUTH PLAINS. HEIGHT FIELDS ON THE WESTERN PERIPHERY OF THIS RIDGE ARE NOT SHOWN TO BUILD ANY...SO THE OPPORTUNITY WILL EXIST FOR ANOTHER ROUND OF SOLAR-POWERED TSTORMS MAINLY NEAR THE NM STATE LINE WHERE OCCASIONAL DISTURBANCES ARE PROGGED TO LIFT NORTH FROM CHIHUAHUA. OTHERWISE...WE CONTINUE TO SIDE WITH THE WARMER SPECTRUM OF MOS GUIDANCE FOR BOTH LOWS AND HIGHS GIVEN THE RECENT OBSERVED TRENDS. LONG TERM... COOLER WEATHER IS ON THE WAY AS WELL AS A SHOT FOR RAIN. BUT BEFORE WE GET THERE...WARM AND DRY WEATHER WILL CONTINUE TO DOMINATE US AS HIGH PRESSURE TO OUR EAST EXTENDS OVER THE REGION. OUR NORTHWESTERN ZONES WILL HAVE A BIT OF A REPRIEVE MONDAY NIGHT AS A WEAKNESS PROPAGATES AROUND THE WESTERN EDGE OF THE RIDGE. THE WEAKNESS MAKES USE OF A SURFACE TROF LOCATED OVER THE SOUTHWESTERN TX PANHANDLE AND FIRES SCATTERED CONVECTION IN THAT REGION. CHANCES ARE ONLY SLIGHT AS THE AVAILABLE MONSOONAL MOISTURE ONLY COVERS A VERY SMALL AREA WHICH COINCIDES WITH THE SURFACE TROF. BY TUESDAY AND INTO WEDNESDAY...THE RIDGE TO OUR EAST BUILDS FURTHER WEST INHIBITING CHANCES FOR ANY RAIN...HOWEVER A LOW AWAITS US OVER THE GREAT BASIN AND IS READY TO MOVE IN AND DEFEAT THE EVIL RIDGE. WITH THE EXCEPTION OF THE GFS...MODELS HAVE BEEN IN DECENT AGREEMENT WITH HANDLING OF THE LOW THE PAST SEVERAL RUNS. THE 12Z RUN YIELDED THE GFS SLOWING THE EASTWARD PROGRESSION OF THE LOW AND IS MORE IN LINE WITH THE OTHER MODELS. THE LOW WILL INITIALLY START OFF CLOSED AS IT MOVES ACROSS THE ROCKIES INTO THE CENTRAL PLAINS DURING WHICH TIME IT WILL SLOWLY BECOME AN OPEN WAVE. BY LATE WEDNESDAY A COLD FRONT SHOULD BE KNOCKING ON OUR DOOR. THE TIMING OF THE FRONT IS SOMEWHAT IN QUESTION WITH TIMINGS RANGING FROM EARLY TO LATE THURSDAY...WITH THURSDAY MORNING BEING THE TIMING CHOICE FOR THE TIME BEING. RAIN CHANCES WILL EXIST ALONG THE FRONT...ESPECIALLY AS THE UPPER LEVEL LOW PUSHES INTO THE REGION. PWATS OVER 1.3 INCHES WILL BE MORE THAN ENOUGH TO AID IN MODERATE RAINFALL AMOUNTS. RAIN CHANCES WILL BE HIGHEST THURSDAY NIGHT INTO EARLY FRIDAY AS A JET MAX PUSHES IN FROM THE WEST ON THE SOUTHEAST SIDE OF THE LOW. AS OF NOW THE JET MAX IS GREATEST OVER OUR SOUTHEASTERN ZONES. THIS COMBINED WITH A DIFFLUENT UPPER PATTERN SHOULD BE MORE THAN EFFICIENT IN DEVELOPING PRECIP. THE LOW WILL HAVE AN EXTENDED VISIT AND REMAIN OVERHEAD THROUGH LATE SUNDAY BEFORE ZONAL FLOW TAKES OVER. TEMPERATURES WILL BE RELATIVELY COOL IN THE SENSE OF TEMPS WILL BE AROUND SEASONAL AVERAGES BUT COOLER THAN THEY WILL BE EARLIER THIS WEEK. DEPENDING ON THE STRENGTH OF THE FRONT...SOME AREAS SUCH AS THE TEXAS PANHANDLE MAY SEE BELOW AVERAGE TEMPS AS COOL AIR OVER MT INTO CA WILL BE PUSHED SOUTHWARD. AS OF THIS AFTERNOON...PARTS OF INTERIOR MT HAVE FAILED TO REACH INTO THE 50S. AS OF NOW THE COOLEST AIR WITH THE FRONT LATER THIS WEEK SHOULD STAY TO OUR NORTH WITH THE COOL SIDE OF THE FORECAST BEING IN THE UPPER 50S. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 65 92 63 90 62 / 10 20 20 10 10 TULIA 69 95 65 93 64 / 20 10 20 10 10 PLAINVIEW 65 95 64 92 64 / 20 10 10 10 10 LEVELLAND 67 94 65 91 64 / 10 10 20 10 10 LUBBOCK 72 96 68 94 68 / 10 10 10 10 10 DENVER CITY 67 95 65 92 65 / 10 10 10 10 10 BROWNFIELD 66 96 66 93 66 / 10 10 10 10 10 CHILDRESS 73 101 72 98 72 / 20 10 10 10 10 SPUR 70 100 68 96 68 / 30 0 10 0 10 ASPERMONT 75 102 72 99 71 / 20 0 10 0 10 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 33/23
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
636 PM CDT SUN AUG 24 2014 .AVIATION... CURRENT RADAR TRENDS SUGGEST THAT KLBB AND KCDS MAY ESCAPE ANY -TSRA IN THE NEXT HOUR OR SO...BUT THERE IS STILL AN OUTSIDE CHANCE. ALSO...SOME GUSTY OUTFLOW WINDS ARE STILL POSSIBLE. OTHERWISE...VFR CONDITIONS WITH SRLY SURFACE WINDS EXPECTED THROUGH MID-AFTERNOON MONDAY. && .PREV DISCUSSION... /ISSUED 343 PM CDT SUN AUG 24 2014/ SHORT TERM... DESPITE OF A WESTWARD EXPANSION OF WEAK RIDGING ALOFT AND VERY LITTLE IF ANY SURFACE FEATURES...AN ADEQUATE BOOST IN THETA-E EARLIER TODAY SUPPLIED MUCH OF THE AREA WITH DEEPER MOISTURE NECESSARY FOR SOME DIURNALLY DRIVEN TSTORMS. NON-HIGH RES MODELS HAVE LARGELY MISSED THE BOAT SO FAR TODAY WITH THE EXPERIMENTAL MODELS PLAYING THE ROLE OF THE DARK HORSE. RAP DATA SHOW THE RICHEST PWATS OF 1.3 INCHES CONFINED EAST OF A BROWNFIELD TO SILVERTON LINE WITH GENERALLY ONE INCH OR LESS FARTHER WEST. ENVIRONMENT IN THE RICHER PWATS IS CHARACTERIZED BY SBCAPES OF 1200-2500 J/KG WITH WEAK SHEAR. THIS THEME WILL PERSIST THROUGH MID-EVENING AT WHICH POINT TSTORMS WILL DWINDLE...BUT UNTIL THEN WE EXPECT ADDITIONAL STRONG TO PERHAPS BRIEFLY SEVERE PULSE MODES WITH MICROBURSTS THE PRIMARY HAZARD. BY MONDAY MORNING...DEEPER MONSOONAL MOISTURE WILL BE TUGGED NORTH INTO NEW MEXICO AROUND THE ZONAL RIDGE AXIS STILL POISED FIRMLY OVER THE SOUTH PLAINS. HEIGHT FIELDS ON THE WESTERN PERIPHERY OF THIS RIDGE ARE NOT SHOWN TO BUILD ANY...SO THE OPPORTUNITY WILL EXIST FOR ANOTHER ROUND OF SOLAR-POWERED TSTORMS MAINLY NEAR THE NM STATE LINE WHERE OCCASIONAL DISTURBANCES ARE PROGGED TO LIFT NORTH FROM CHIHUAHUA. OTHERWISE...WE CONTINUE TO SIDE WITH THE WARMER SPECTRUM OF MOS GUIDANCE FOR BOTH LOWS AND HIGHS GIVEN THE RECENT OBSERVED TRENDS. LONG TERM... COOLER WEATHER IS ON THE WAY AS WELL AS A SHOT FOR RAIN. BUT BEFORE WE GET THERE...WARM AND DRY WEATHER WILL CONTINUE TO DOMINATE US AS HIGH PRESSURE TO OUR EAST EXTENDS OVER THE REGION. OUR NORTHWESTERN ZONES WILL HAVE A BIT OF A REPRIEVE MONDAY NIGHT AS A WEAKNESS PROPAGATES AROUND THE WESTERN EDGE OF THE RIDGE. THE WEAKNESS MAKES USE OF A SURFACE TROF LOCATED OVER THE SOUTHWESTERN TX PANHANDLE AND FIRES SCATTERED CONVECTION IN THAT REGION. CHANCES ARE ONLY SLIGHT AS THE AVAILABLE MONSOONAL MOISTURE ONLY COVERS A VERY SMALL AREA WHICH COINCIDES WITH THE SURFACE TROF. BY TUESDAY AND INTO WEDNESDAY...THE RIDGE TO OUR EAST BUILDS FURTHER WEST INHIBITING CHANCES FOR ANY RAIN...HOWEVER A LOW AWAITS US OVER THE GREAT BASIN AND IS READY TO MOVE IN AND DEFEAT THE EVIL RIDGE. WITH THE EXCEPTION OF THE GFS...MODELS HAVE BEEN IN DECENT AGREEMENT WITH HANDLING OF THE LOW THE PAST SEVERAL RUNS. THE 12Z RUN YIELDED THE GFS SLOWING THE EASTWARD PROGRESSION OF THE LOW AND IS MORE IN LINE WITH THE OTHER MODELS. THE LOW WILL INITIALLY START OFF CLOSED AS IT MOVES ACROSS THE ROCKIES INTO THE CENTRAL PLAINS DURING WHICH TIME IT WILL SLOWLY BECOME AN OPEN WAVE. BY LATE WEDNESDAY A COLD FRONT SHOULD BE KNOCKING ON OUR DOOR. THE TIMING OF THE FRONT IS SOMEWHAT IN QUESTION WITH TIMINGS RANGING FROM EARLY TO LATE THURSDAY...WITH THURSDAY MORNING BEING THE TIMING CHOICE FOR THE TIME BEING. RAIN CHANCES WILL EXIST ALONG THE FRONT...ESPECIALLY AS THE UPPER LEVEL LOW PUSHES INTO THE REGION. PWATS OVER 1.3 INCHES WILL BE MORE THAN ENOUGH TO AID IN MODERATE RAINFALL AMOUNTS. RAIN CHANCES WILL BE HIGHEST THURSDAY NIGHT INTO EARLY FRIDAY AS A JET MAX PUSHES IN FROM THE WEST ON THE SOUTHEAST SIDE OF THE LOW. AS OF NOW THE JET MAX IS GREATEST OVER OUR SOUTHEASTERN ZONES. THIS COMBINED WITH A DIFFLUENT UPPER PATTERN SHOULD BE MORE THAN EFFICIENT IN DEVELOPING PRECIP. THE LOW WILL HAVE AN EXTENDED VISIT AND REMAIN OVERHEAD THROUGH LATE SUNDAY BEFORE ZONAL FLOW TAKES OVER. TEMPERATURES WILL BE RELATIVELY COOL IN THE SENSE OF TEMPS WILL BE AROUND SEASONAL AVERAGES BUT COOLER THAN THEY WILL BE EARLIER THIS WEEK. DEPENDING ON THE STRENGTH OF THE FRONT...SOME AREAS SUCH AS THE TEXAS PANHANDLE MAY SEE BELOW AVERAGE TEMPS AS COOL AIR OVER MT INTO CA WILL BE PUSHED SOUTHWARD. AS OF THIS AFTERNOON...PARTS OF INTERIOR MT HAVE FAILED TO REACH INTO THE 50S. AS OF NOW THE COOLEST AIR WITH THE FRONT LATER THIS WEEK SHOULD STAY TO OUR NORTH WITH THE COOL SIDE OF THE FORECAST BEING IN THE UPPER 50S. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 65 92 63 90 62 / 10 20 20 10 10 TULIA 69 95 65 93 64 / 10 10 20 10 10 PLAINVIEW 65 95 64 92 64 / 10 10 10 10 10 LEVELLAND 67 94 65 91 64 / 10 10 20 10 10 LUBBOCK 72 96 68 94 68 / 10 10 10 10 10 DENVER CITY 67 95 65 92 65 / 10 10 10 10 10 BROWNFIELD 66 96 66 93 66 / 10 10 10 10 10 CHILDRESS 73 101 72 98 72 / 20 10 10 10 10 SPUR 70 100 68 96 68 / 20 0 10 0 10 ASPERMONT 75 102 72 99 71 / 10 0 10 0 10 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 33
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1051 PM CDT SUN AUG 24 2014 .UPDATE... ISSUED AT 913 PM CDT SUN AUG 24 2014 THE FIRST WAVE OF CONVECTION HAS DEVELOPED AND TRACKED TO THE NORTHEAST ACROSS EASTERN MINNESOTA AND NORTHWEST WISCONSIN WITH JUST A FEW SHOWERS LEFT OVER GOING DOWN INTO CENTRAL IOWA. THE FOCUS NOW SHIFTS TO THE SECOND WAVE OF CONVECTION THAT IS EXPECTED TO DEVELOP OVERNIGHT AS A WEAK MID LEVEL SHORT WAVE TROUGH LIFTS NORTHWARD FROM THE CENTRAL PLAINS. THIS CONVECTION IS EXPECTED TO DEVELOP OUT AHEAD OF A EASTWARD PROPAGATING SURFACE COLD FRONT THAT CURRENTLY EXTENDS FROM THE TWIN CITIES DOWN THE I-35 CORRIDOR AND THEN BACK SOUTHWEST TOWARD OMAHA. THIS AIR MASS AHEAD OF THE FRONT WILL REMAIN VERY UNSTABLE THROUGH THE OVERNIGHT HOURS WITH 25.00Z RAP SOUNDINGS SHOWING ABOUT 2000-4000 J/KG OF ELEVATED INSTABILITY OUT IN THE WARM SECTOR. HOWEVER...THE WIND FIELD FROM THE TOP OF THE LOW LEVEL INVERSION ON UP IS ALL UNIDIRECTIONAL AND AT THE SAME SPEED...SO THERE IS ALMOST NO WIND SHEAR TO WORK WITH. THE PAST FEW RUNS OF THE HRRR HAVE BEEN FAIRLY CONSISTENT WITH SHOWING CONVECTION INITIATING OVER CENTRAL IOWA OVER THE NEXT FEW HOURS AND THEN DEVELOPING NORTHWARD ALONG THE FRONT INTO WESTERN WISCONSIN. GIVEN THE HIGH INSTABILITY...LOW SHEAR ENVIRONMENT...CAN NOT RULE OUT A FEW ISOLATED STORMS THAT COULD PRODUCE SOME MARGINALLY SEVERE HAIL ALONG WITH BRIEF HEAVY DOWNPOURS...BUT IT SHOULD NOT BE A WIDESPREAD EVENT. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT) ISSUED AT 304 PM CDT SUN AUG 24 2014 THE MAIN CONCERN IS WITH THE RAIN CHANCES THROUGH THE PERIOD. SURFACE ANALYSIS THIS AFTERNOON SHOWS AN AREA OF LOW PRESSURE OVER NORTH DAKOTA WITH A COLD FRONT TRAILING SOUTH THROUGH WESTERN MINNESOTA INTO NEBRASKA. WATER VAPOR IMAGERY SHOWS A WOUND UP UPPER LEVEL LOW OVER EASTERN MONTANA THAT WAS LIFTING TO THE NORTHEAST. THE 24.12Z MODELS ARE ALL IN REASONABLY GOOD AGREEMENT WITH THE HANDLING OF THE UPPER LEVEL SYSTEM. IT WILL CONTINUE TO MOVE NORTHEAST REACHING WESTERN ONTARIO BY MONDAY EVENING. THE MAIN SHORT WAVE TROUGH WITH THIS SYSTEM IS VERY NEAR THE UPPER LEVEL LOW AND IS EXPECTED TO REMAIN THAT WAY. THIS TAKES THE PV ADVECTION IN THE 500-300 MB LAYER FROM EASTERN NORTH DAKOTA ACROSS NORTHWEST MINNESOTA INTO ONTARIO. THIS WILL TAKE THE BULK OF THE UPPER LEVEL FORCING WELL NORTH OF THE REGION BUT SOME UPPER LEVEL DIVERGENCE SHOULD SPREAD ACROSS THE AREA TONIGHT AS THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET MOVES OVER. AS THE FRONT MOVES IN TONIGHT...SOME WEAK FRONTOGENESIS SHOULD OCCUR IN THE 850-500 MB LAYER. GOOD LOW LEVEL WARM AIR ADVECTION AHEAD OF THE FRONT WILL HELP TO GENERATE 4 TO 6 UBAR/S OF UP GLIDE ON THE 310K ISENTROPIC SURFACE WITH THE MOISTURE TRANSPORT ON THIS SURFACE EXPECTED TO BE INTO THE AREA FROM LATE EVENING THROUGH THE OVERNIGHT HOURS. THE 24.12Z SOUNDING FROM KMPX SHOWS A STRONG CAP IS IN PLACE BETWEEN 850 AND 700 MB AND THE CONCERN BECOMES WHETHER THE FORCING WILL BE STRONG ENOUGH TO BREAK THE CAP. THE 24.12Z NAM BUFKIT SOUNDINGS SUGGEST THAT THE CAP MAY WEAKEN BUT NOT TOTALLY BREAK AND THIS IS REFLECTED IN THE MODEL ONLY PRODUCING SOME SCATTERED ACTIVITY ALONG THE FRONT AS IT COMES THROUGH. THE 24.12Z GFS AND ECMWF SHOW MUCH MORE QPF ALONG THE FRONT SUGGESTING THE CAP WILL BREAK. THE SHORT TERM MESO-MODELS ARE ABOUT AS EQUALLY SPLIT. THE 24.12Z HI-RES ARW LOOKS TO HOLD THE CAP IN PLACE WITH ALMOST NO ACTIVITY OVER THE AREA...WHILE THE HI-RES NMM IS CLOSER TO THE NAM WITH JUST SOME SCATTERED ACTIVITY. THE 24.12Z SPC WRF LOOKS TO DISSIPATE THE CAP AS EARLY AS LATE THIS AFTERNOON WITH LOTS OF CONVECTION DEVELOPING ACROSS MINNESOTA AND MOVING ACROSS THE AREA IN THE NIGHT. OUTPUT FROM THE 24.12Z HOP WRF IS ALSO SPLIT WITH A COUPLE OF MEMBERS DEVELOPING LOTS OF CONVECTION AND THE OTHER TWO STAYING WITH JUST SCATTERED ACTIVITY. IF THE CAP WOULD BREAK...THE BEST CHANCE FOR THIS TO OCCUR WOULD BE ACROSS THE NORTHERN SECTIONS OF THE FORECAST AREA CLOSER TO THE DYNAMIC FORCING AND WILL MAINTAIN THE LIKELY RAIN CHANCES ACROSS THAT AREA WHILE TAPERING DOWN TO 30 TO 40 PERCENT CHANCE ACROSS THE SOUTH. SOME THREAT OF SEVERE ACROSS THE NORTH AS WELL IF THE CAP CAN BREAK. PLENTY OF INSTABILITY WILL REMAIN IN PLACE AHEAD OF THE FRONT WITH THE NAM SHOWING 1000-1500 J/KG OF ML CAPE ALONG WITH 40 KNOTS OF 0-3KM SHEAR. DAMAGING WINDS AND HEAVY RAIN SHOULD BE THE MAIN THREATS AS WARM CLOUD DEPTHS WILL REMAIN IN THE 3.5 TO 4 KM RANGE AHEAD OF THE FRONT. MAY ALSO HAVE TO AWARE OF A SPIN UP TORNADO THREAT AS A DIFFERENTIAL HEATING BOUNDARY IS IN PLACE ON THE CLOUD EDGE. IF THIS BOUNDARY MAINTAINS ITSELF INTO THE EVENING...THE NAM INDICATES THE 0-1KM SHEAR WILL INCREASE TO AROUND 25 KNOTS. THE FRONT SHOULD THEN PASS THROUGH THE AREA MONDAY WITH THE POSSIBILITY OF SOME SCATTERED ACTIVITY ALONG IT. NOT MUCH FORCING ALONG THE FRONT BUT COULD SEE A DIURNAL INCREASE IN THE ACTIVITY DURING THE AFTERNOON WHEN THE ML CAPE SHOULD AGAIN BE IN THE 2000-3000 J/KG RANGE. THE MODELS THEN HAVE REALLY TRENDED TOWARD PUSHING THIS FRONT FARTHER SOUTH FROM MONDAY NIGHT INTO TUESDAY NIGHT AS THE HIGH PRESSURE BUILDING IN BEHIND IT IS MUCH STRONGER. MODELS CONTINUE TO SHOW A SHORT WAVE TROUGH MOVING ALONG THE UPPER LEVEL RIDGE AXIS AND INTERACTING WITH THE FRONT. IF THE FRONT DOES PUSH AS FAR SOUTH AS THE MODELS ARE CURRENTLY INDICATING...THIS WOULD PLACE THE HIGHEST RAIN CHANCES SOUTH OF THE IOWA/MINNESOTA BORDER. WILL MAINTAIN SOME 50 TO 60 PERCENT CHANCES FROM MONDAY NIGHT INTO TUESDAY NIGHT...BUT LIMIT THEM TO THE SOUTHERN SECTIONS. .LONG TERM...(WEDNESDAY THROUGH SUNDAY) ISSUED AT 304 PM CDT SUN AUG 24 2014 THE FRONT IS EXPECTED TO STILL NOT BE TOO FAR SOUTH OF THE AREA BY THE MIDDLE OF THE WEEK. THE 24.12Z ECMWF AND GFS IN DECENT AGREEMENT OF BRINGING ANOTHER SHORT WAVE TROUGH ACROSS THE TOP OF THE RIDGE AXIS WITH A SURFACE LOW MOVING ALONG THE FRONT. BASED ON THIS...WILL HAVE UP TO 50 PERCENT CHANCES ACROSS THE SOUTH FROM WEDNESDAY INTO THURSDAY NIGHT. THE RAIN CHANCES SHOULD THEN DIMINISH TO CLOSE OUT THE WEEK INTO THE WEEKEND AS HIGH PRESSURE BUILDS IN BEHIND THE MID WEEK SYSTEM. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1051 PM CDT SUN AUG 24 2014 SHOWERS AND THUNDERSTORMS ARE LIKELY OVERNIGHT INTO MONDAY MORNING AHEAD OF A COLD FRONT THAT CURRENTLY IS IN EASTERN MINNESOTA/CENTRAL IOWA. A HIGHLY UNSTABLE AIR MASS AHEAD OF THIS FRONT SHOULD HELP TO KEEP THIS LINE OF DEVELOPING THUNDERSTORMS GOING AS THEY TRACK TO THE EAST OVERNIGHT WITH VISIBILITY LIKELY DROPPING DOWN TO IFR FOR A BRIEF PERIOD. WINDS WILL THEN SHIFT AROUND TO THE WEST THIS AFTERNOON ON INTO MONDAY NIGHT AS THE FRONT SLOWLY SHIFTS TO THE EAST. && .HYDROLOGY... ISSUED AT 304 PM CDT SUN AUG 24 2014 HEAVY RAIN WILL BE A THREAT WITH ANY STORMS THAT DEVELOP TONIGHT. WARM CLOUD DEPTHS WILL BE IN THE 3.5 TO 4 KM RANGE WITH PRECIPITABLE WATERS APPROACHING TWO INCHES. THE CONCERN FOR HEAVY RAIN AND POSSIBLE FLOODING WITH THE STALLED FRONT FOR THE EARLY PART OF THE WEEK ARE DIMINISHING WITH THE FRONT EXPECTED TO PUSH FARTHER SOUTH. THE HIGHEST AXIS OF PRECIPITABLE WATERS SHOULD LAY UP SOUTH OF THE FRONT ACROSS SOUTHERN IOWA/NORTHERN MISSOURI INTO ILLINOIS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE...HALBACH SHORT TERM...04 LONG TERM...04 AVIATION...HALBACH HYDROLOGY...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
913 PM CDT SUN AUG 24 2014 .UPDATE... ISSUED AT 913 PM CDT SUN AUG 24 2014 THE FIRST WAVE OF CONVECTION HAS DEVELOPED AND TRACKED TO THE NORTHEAST ACROSS EASTERN MINNESOTA AND NORTHWEST WISCONSIN WITH JUST A FEW SHOWERS LEFT OVER GOING DOWN INTO CENTRAL IOWA. THE FOCUS NOW SHIFTS TO THE SECOND WAVE OF CONVECTION THAT IS EXPECTED TO DEVELOP OVERNIGHT AS A WEAK MID LEVEL SHORT WAVE TROUGH LIFTS NORTHWARD FROM THE CENTRAL PLAINS. THIS CONVECTION IS EXPECTED TO DEVELOP OUT AHEAD OF A EASTWARD PROPAGATING SURFACE COLD FRONT THAT CURRENTLY EXTENDS FROM THE TWIN CITIES DOWN THE I-35 CORRIDOR AND THEN BACK SOUTHWEST TOWARD OMAHA. THIS AIR MASS AHEAD OF THE FRONT WILL REMAIN VERY UNSTABLE THROUGH THE OVERNIGHT HOURS WITH 25.00Z RAP SOUNDINGS SHOWING ABOUT 2000-4000 J/KG OF ELEVATED INSTABILITY OUT IN THE WARM SECTOR. HOWEVER...THE WIND FIELD FROM THE TOP OF THE LOW LEVEL INVERSION ON UP IS ALL UNIDIRECTIONAL AND AT THE SAME SPEED...SO THERE IS ALMOST NO WIND SHEAR TO WORK WITH. THE PAST FEW RUNS OF THE HRRR HAVE BEEN FAIRLY CONSISTENT WITH SHOWING CONVECTION INITIATING OVER CENTRAL IOWA OVER THE NEXT FEW HOURS AND THEN DEVELOPING NORTHWARD ALONG THE FRONT INTO WESTERN WISCONSIN. GIVEN THE HIGH INSTABILITY...LOW SHEAR ENVIRONMENT...CAN NOT RULE OUT A FEW ISOLATED STORMS THAT COULD PRODUCE SOME MARGINALLY SEVERE HAIL ALONG WITH BRIEF HEAVY DOWNPOURS...BUT IT SHOULD NOT BE A WIDESPREAD EVENT. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT) ISSUED AT 304 PM CDT SUN AUG 24 2014 THE MAIN CONCERN IS WITH THE RAIN CHANCES THROUGH THE PERIOD. SURFACE ANALYSIS THIS AFTERNOON SHOWS AN AREA OF LOW PRESSURE OVER NORTH DAKOTA WITH A COLD FRONT TRAILING SOUTH THROUGH WESTERN MINNESOTA INTO NEBRASKA. WATER VAPOR IMAGERY SHOWS A WOUND UP UPPER LEVEL LOW OVER EASTERN MONTANA THAT WAS LIFTING TO THE NORTHEAST. THE 24.12Z MODELS ARE ALL IN REASONABLY GOOD AGREEMENT WITH THE HANDLING OF THE UPPER LEVEL SYSTEM. IT WILL CONTINUE TO MOVE NORTHEAST REACHING WESTERN ONTARIO BY MONDAY EVENING. THE MAIN SHORT WAVE TROUGH WITH THIS SYSTEM IS VERY NEAR THE UPPER LEVEL LOW AND IS EXPECTED TO REMAIN THAT WAY. THIS TAKES THE PV ADVECTION IN THE 500-300 MB LAYER FROM EASTERN NORTH DAKOTA ACROSS NORTHWEST MINNESOTA INTO ONTARIO. THIS WILL TAKE THE BULK OF THE UPPER LEVEL FORCING WELL NORTH OF THE REGION BUT SOME UPPER LEVEL DIVERGENCE SHOULD SPREAD ACROSS THE AREA TONIGHT AS THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET MOVES OVER. AS THE FRONT MOVES IN TONIGHT...SOME WEAK FRONTOGENESIS SHOULD OCCUR IN THE 850-500 MB LAYER. GOOD LOW LEVEL WARM AIR ADVECTION AHEAD OF THE FRONT WILL HELP TO GENERATE 4 TO 6 UBAR/S OF UP GLIDE ON THE 310K ISENTROPIC SURFACE WITH THE MOISTURE TRANSPORT ON THIS SURFACE EXPECTED TO BE INTO THE AREA FROM LATE EVENING THROUGH THE OVERNIGHT HOURS. THE 24.12Z SOUNDING FROM KMPX SHOWS A STRONG CAP IS IN PLACE BETWEEN 850 AND 700 MB AND THE CONCERN BECOMES WHETHER THE FORCING WILL BE STRONG ENOUGH TO BREAK THE CAP. THE 24.12Z NAM BUFKIT SOUNDINGS SUGGEST THAT THE CAP MAY WEAKEN BUT NOT TOTALLY BREAK AND THIS IS REFLECTED IN THE MODEL ONLY PRODUCING SOME SCATTERED ACTIVITY ALONG THE FRONT AS IT COMES THROUGH. THE 24.12Z GFS AND ECMWF SHOW MUCH MORE QPF ALONG THE FRONT SUGGESTING THE CAP WILL BREAK. THE SHORT TERM MESO-MODELS ARE ABOUT AS EQUALLY SPLIT. THE 24.12Z HI-RES ARW LOOKS TO HOLD THE CAP IN PLACE WITH ALMOST NO ACTIVITY OVER THE AREA...WHILE THE HI-RES NMM IS CLOSER TO THE NAM WITH JUST SOME SCATTERED ACTIVITY. THE 24.12Z SPC WRF LOOKS TO DISSIPATE THE CAP AS EARLY AS LATE THIS AFTERNOON WITH LOTS OF CONVECTION DEVELOPING ACROSS MINNESOTA AND MOVING ACROSS THE AREA IN THE NIGHT. OUTPUT FROM THE 24.12Z HOP WRF IS ALSO SPLIT WITH A COUPLE OF MEMBERS DEVELOPING LOTS OF CONVECTION AND THE OTHER TWO STAYING WITH JUST SCATTERED ACTIVITY. IF THE CAP WOULD BREAK...THE BEST CHANCE FOR THIS TO OCCUR WOULD BE ACROSS THE NORTHERN SECTIONS OF THE FORECAST AREA CLOSER TO THE DYNAMIC FORCING AND WILL MAINTAIN THE LIKELY RAIN CHANCES ACROSS THAT AREA WHILE TAPERING DOWN TO 30 TO 40 PERCENT CHANCE ACROSS THE SOUTH. SOME THREAT OF SEVERE ACROSS THE NORTH AS WELL IF THE CAP CAN BREAK. PLENTY OF INSTABILITY WILL REMAIN IN PLACE AHEAD OF THE FRONT WITH THE NAM SHOWING 1000-1500 J/KG OF ML CAPE ALONG WITH 40 KNOTS OF 0-3KM SHEAR. DAMAGING WINDS AND HEAVY RAIN SHOULD BE THE MAIN THREATS AS WARM CLOUD DEPTHS WILL REMAIN IN THE 3.5 TO 4 KM RANGE AHEAD OF THE FRONT. MAY ALSO HAVE TO AWARE OF A SPIN UP TORNADO THREAT AS A DIFFERENTIAL HEATING BOUNDARY IS IN PLACE ON THE CLOUD EDGE. IF THIS BOUNDARY MAINTAINS ITSELF INTO THE EVENING...THE NAM INDICATES THE 0-1KM SHEAR WILL INCREASE TO AROUND 25 KNOTS. THE FRONT SHOULD THEN PASS THROUGH THE AREA MONDAY WITH THE POSSIBILITY OF SOME SCATTERED ACTIVITY ALONG IT. NOT MUCH FORCING ALONG THE FRONT BUT COULD SEE A DIURNAL INCREASE IN THE ACTIVITY DURING THE AFTERNOON WHEN THE ML CAPE SHOULD AGAIN BE IN THE 2000-3000 J/KG RANGE. THE MODELS THEN HAVE REALLY TRENDED TOWARD PUSHING THIS FRONT FARTHER SOUTH FROM MONDAY NIGHT INTO TUESDAY NIGHT AS THE HIGH PRESSURE BUILDING IN BEHIND IT IS MUCH STRONGER. MODELS CONTINUE TO SHOW A SHORT WAVE TROUGH MOVING ALONG THE UPPER LEVEL RIDGE AXIS AND INTERACTING WITH THE FRONT. IF THE FRONT DOES PUSH AS FAR SOUTH AS THE MODELS ARE CURRENTLY INDICATING...THIS WOULD PLACE THE HIGHEST RAIN CHANCES SOUTH OF THE IOWA/MINNESOTA BORDER. WILL MAINTAIN SOME 50 TO 60 PERCENT CHANCES FROM MONDAY NIGHT INTO TUESDAY NIGHT...BUT LIMIT THEM TO THE SOUTHERN SECTIONS. .LONG TERM...(WEDNESDAY THROUGH SUNDAY) ISSUED AT 304 PM CDT SUN AUG 24 2014 THE FRONT IS EXPECTED TO STILL NOT BE TOO FAR SOUTH OF THE AREA BY THE MIDDLE OF THE WEEK. THE 24.12Z ECMWF AND GFS IN DECENT AGREEMENT OF BRINGING ANOTHER SHORT WAVE TROUGH ACROSS THE TOP OF THE RIDGE AXIS WITH A SURFACE LOW MOVING ALONG THE FRONT. BASED ON THIS...WILL HAVE UP TO 50 PERCENT CHANCES ACROSS THE SOUTH FROM WEDNESDAY INTO THURSDAY NIGHT. THE RAIN CHANCES SHOULD THEN DIMINISH TO CLOSE OUT THE WEEK INTO THE WEEKEND AS HIGH PRESSURE BUILDS IN BEHIND THE MID WEEK SYSTEM. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 653 PM CDT SUN AUG 24 2014 THE MAIN FOCUS AT THE TAF SITES IS WITH THE CONVECTIVE TRENDS TONIGHT AS A COLD FRONT MOVES THROUGH THE REGION. A BATCH OF SHOWERS/STORMS HAS DEVELOPED IN NC IA/SC MN AND HAS BEEN TRACKING TO THE NORTHEAST AND WILL BE CLOSE TO RST. AFTER A BRIEF BREAK THIS EVENING...A SECOND ROUND OF CONVECTION IS POSSIBLE OVERNIGHT AND SHOULD BE A BIT MORE WIDESPREAD. THE MAIN PERIOD IT IS EXPECTED TO COME THROUGH RST WOULD BE BETWEEN 5-9Z AND LSE BETWEEN 8-11Z. SOME DROPS TO MVFR/IFR VISIBILITY WILL BE POSSIBLE IF THE SHOWERS/STORMS DO BECOME WIDESPREAD. WINDS WILL COME AROUND TO THE WEST TOMORROW AFTERNOON AS THE COLD FRONT PASSES THROUGH AND BRINGS AN END TO THE CHANCES FOR PRECIPITATION. && .HYDROLOGY... ISSUED AT 304 PM CDT SUN AUG 24 2014 HEAVY RAIN WILL BE A THREAT WITH ANY STORMS THAT DEVELOP TONIGHT. WARM CLOUD DEPTHS WILL BE IN THE 3.5 TO 4 KM RANGE WITH PRECIPITABLE WATERS APPROACHING TWO INCHES. THE CONCERN FOR HEAVY RAIN AND POSSIBLE FLOODING WITH THE STALLED FRONT FOR THE EARLY PART OF THE WEEK ARE DIMINISHING WITH THE FRONT EXPECTED TO PUSH FARTHER SOUTH. THE HIGHEST AXIS OF PRECIPITABLE WATERS SHOULD LAY UP SOUTH OF THE FRONT ACROSS SOUTHERN IOWA/NORTHERN MISSOURI INTO ILLINOIS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE...HALBACH SHORT TERM...04 LONG TERM...04 AVIATION...HALBACH HYDROLOGY...04
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
702 PM CDT SUN AUG 24 2014 UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE .SHORT TERM...TONIGHT AND MONDAY ISSUED AT 243 PM CDT SUN AUG 24 2014 THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW UPPER LEVEL LOW PRESSURE OVER EASTERN MONTANA AND A DOUBLE BARRELED SURFACE LOW OVER NORTH DAKOTA. A WARM FRONT EXTENDS FROM THIS SURFACE LOW OVER SOUTHWEST WISCONSIN...WHICH MARKS THE TRANSITION FROM MOSTLY CLOUDY SKIES TO CLEAR CONDITIONS. A COLD FRONT EXTENDS SOUTHWARD OVER THE CENTRAL PLAINS AND IS LARGELY INACTIVE AT THIS HOUR THOUGH THAT MIGHT BE CHANGING OVER CENTRAL MINNESOTA WHERE ML CAPES HAVE EXCEEDED 2000 J/KG. A FEW OTHER ELEVATED STORMS CONTINUE TO DEVELOP OVER NORTHWEST WISCONSIN WITHIN THE TAIL END OF A VORT MAX. WILL ADD A CHANCE TO N-C WISCONSIN BETWEEN 21Z AND 00Z. AS THE UPPER LOW AND COLD FRONT MOVE EAST...THUNDERSTORM AND SEVERE WEATHER CHANCES ARE THE MAIN FORECAST CONCERNS. TONIGHT...THE LARGE UPPER LOW WILL MOVE ACROSS NORTH DAKOTA INTO THE LAKE WINNIPEG REGION. MID-LEVEL HEIGHT FALLS FROM THE SYSTEM WILL MOVE INTO THE WESTERN GREAT LAKES...WHICH WILL HELP PUSH A WEAK COLD FRONT INTO WESTERN WISCONSIN AFTER MIDNIGHT. CONVERGENCE ALONG THE FRONT IS RELATIVELY WEAK...BUT ELEVATED INSTABILITY APPROX 1000-1500 J/KG (ROUGH ESTIMATE) WILL MOVE INTO CENTRAL AND NORTH-CENTRAL WISCONSIN AFTER MIDNIGHT. BECAUSE OF THE WEAK FORCING...KEPT CHANCES OF PRECIP IN THE SCATTERED RANGE. THE MAGNITUDE OF CAPE AND WIND SHEAR AROUND 30 KTS WOULD SUPPORT A CHANCE OF STRONG STORMS THAT COULD PRODUCE NEAR SEVERE HAIL AND WIND GUSTS. WILL LEAVE A MENTION OF THIS POSSIBILITY IN THE HWO. THE MESO MODELS CONTINUE TO SHOW CONVECTION DEVELOPING OVER CENTRAL MINNESOTA LATER THIS AFTERNOON BEFORE TRACKING THE STORMS INTO NORTH-CENTRAL WISCONSIN AFTER 06Z. THIS STILL SEEMS POSSIBLE BASED ON THE DESTABILIZATION TAKING PLACE OVER CENTRAL MINNESOTA. THE STORMS SHOULD WEAKEN AS THEY MOVE EAST LATE TONIGHT DUE TO DIMINISHING INSTABILITY. OTHERWISE...LOOK FOR A MUGGY EVENING WITH LOWS DROPPING INTO THE MIDDLE AND UPPER 60S. MONDAY...THE FRONT WILL MAKE LITTLE PROGRESS TO THE EAST AND INTO NORTH-CENTRAL WISCONSIN DURING THE AFTERNOON. SPOTTY SHOWERS AND STORMS WILL BE POSSIBLE AHEAD OF THE FRONT DURING THE MORNING ACROSS MUCH OF THE AREA. ASSUMING COVERAGE IS NOT MORE THAN ADVERTISED...LOW LEVEL SOUTHWEST WINDS WILL PUSH TEMPS INTO THE UPPER 80S OR LOWER 90S OVER THE EASTERN FORECAST AREA. COMBINED WITH DEWPOINTS AROUND 70 DEGREES...ML CAPES ARE PROJECTED TO REACH 2K-3K J/KG WITH BULK SHEARS AROUND 30 KTS. CONVERGENCE ALONG THE FRONT WILL REMAIN WEAK BUT CANNOT RULE OUT ISOLATED OR SCATTERED STRONG TO SEVERE STORMS OVER THE EAST DURING THE AFTERNOON WITH THAN KIND OF INSTABILITY AND SHEAR. DRIER MID-LEVEL AIR WILL WORK INTO CENTRAL AND NORTH-CENTRAL WISCONSIN DURING THE AFTERNOON...WHICH WILL MAKE IT HARDER FOR STORMS TO INITIATE. THE COMBINATION OF HEAT AND HUMIDITY WILL PUSH HEAT INDICES INTO THE MIDDLE 90S. .LONG TERM...MONDAY NIGHT THROUGH SUNDAY ISSUED AT 243 PM CDT SUN AUG 24 2014 MODELS CONTINUE TO INDICATE A RATHER AMPLIFIED MEAN FLOW PATTERN ACROSS THE CONUS WITH AN UPPER TROF CURRENTLY OVER THE INTER MOUNTAIN WEST AND SIG RIDGE OVER THE EASTERN LAKES. THE MOVEMENT OF UPPER LOW OUT OF TROF INTO THE WESTERN LAKES EARLY IN THE PERIOD WILL BE THE PRIMARY WEATHER FEATURE TO IMPACT OUR WEATHER. BY LATE THIS WEEK...MODELS CONTINUE TO SHOW LINGERING PIECE OF TROF MEANDERING INTO THE CENTRAL U.S. THE MOVEMENT OF THIS FEATURE CONTINUES TO SLOW AS IT REMAINS CUT OFF FROM MAIN BAND OF WESTERLIES EXPECTED TO LIE OVER SOUTHERN CANADA. FORECAST CONFIDENCE LOW THU NIGHT ONWARD. TREND IN SHORTER RANGE IS TO CONTINUE TO SLOW PASSAGE OF COLD FRONT MONDAY WITH FRONT STILL BISECTING CWA AT 00Z TUE. HAVE CONTINUE SCATTERED/CHANCE POPS MAINLY SOUTH AND EAST GIVEN AVAILABLE INSTABILITY. LITTLE DYNAMICS BESIDES FRONT TO SUPPORT GOING ANY HIGHER WITH POPS. CONSISTENCY SEEN IN MODELS TO PUSH FRONT AND PCPN MAINLY SOUTH OF CWA AS HIGH PRESSURE AND DRIER AIR MASS MOVES IN OVER NORTHERN WI TUE INTO THU. CONCERN THIS PERIOD ON TEMPS. DRIER AIR...SUN AND LOW LEVEL TEMPS AT OR SLIGHTLY BELOW NORMAL SHOULD SUPPORT TEMPS IN THE LOWER TO MIDDLE 70S. WILL HAVE EAST FLOW OFF LAKE THOUGH LAKE SURFACE TEMPS NOW IN MID TO UPPER 60S SO HAVE CONFINED COOLING TO CLOSER TO THE COAST. HAVE BUMPED MAX TEMPS UP A BIT MID WEEK. && .AVIATION...FOR 00Z TAF ISSUANCE ISSUED AT 702 PM CDT SUN AUG 24 2014 MVFR CEILINGS IN NORTHCENTRAL WISCONSIN WILL DIMINISH THIS EVENING AND MUCH OF THE AREA SHOULD BE VFR FOR PART OF THE NIGHT UNTIL A BROKEN AREA OF SHOWERS AND THUNDERSTORMS ARRIVES LATE TONIGHT FROM THE WEST. THE ACTIVITY WILL PROBABLY ARRIVE IN RHINELANDER AND WAUSAU BETWEEN 07 AND 09Z AND AT APPLETON...OSHKOSH AND GREEN BAY BETWEEN 10Z AND 12Z IF IT HOLDS TOGETHER. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TE AVIATION.......RDM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
653 PM CDT SUN AUG 24 2014 .UPDATE... ISSUED AT 600 PM CDT SUN AUG 24 2014 MONITORING CONVECTIVE TRENDS ACROSS THE REGION...WITH A PARTICULAR FOCUS ON SOUTHEAST MINNESOTA INTO THE EARLY EVENING HOURS. THE 24.22Z RAP ANALYSIS SHOWS A VERY UNSTABLE AIR MASS IS CENTERED ALONG THE MISSISSIPPI RIVER WITH UPWARDS OF 3000-5000 J/KG OF SURFACE BASED CAPE NOSING UP TOWARD THE TWIN CITIES. HOWEVER...THIS AIR MASS APPEARS TO BE CAPPED OFF DUE TO THE LACK OF A CUMULUS FIELD ACROSS SE MN/NE IA/W WI. ALSO...DEEP WIND SHEAR IS ALSO VERY LACKING THIS FAR SOUTH...SO WHILE SOME CONVECTION HAS INITIATED ACROSS NC IA/SC MN...IT HAS BEEN VERY PULSEY AND CAN NOT MAINTAIN ITSELF FOR VERY LONG. FURTHER NORTH WHERE THERE IS DEEPER WIND SHEAR AND BETTER CONVERGENCE IN THE SURFACE FEATURES...STORMS ARE QUICKLY GOING SEVERE. WHILE THERE WILL BE ABOUT A 2-3 HOUR PERIOD FROM NOW THROUGH 9 PM WHERE THIS CONVECTION WILL COME THROUGH MOWER/DODGE/OLMSTED COUNTIES...EXPECTING THAT IT WILL STAY UNORGANIZED AND NOT SEVERE. SOME OF THIS CONVECTION COULD MAKE IT INTO ROCHESTER AROUND 7PM...BUT THE NORTHERN EDGE OF THE CAP APPEARS TO BE AT OR JUST TO THE NORTH OF THE CITY...WHICH WOULD HELP TO KEEP THEM DRY THIS EVENING. BEYOND THIS...THERE APPEARS TO BE A SECOND WAVE OF CONVECTION POSSIBLE OVERNIGHT AS THE MAIN TROUGH/SURFACE COLD FRONT APPROACH FROM THE WEST. INSTABILITY REMAINS HIGH OVERNIGHT...BUT THE OVERALL SHEAR IS LACKING WHICH SHOULD KEEP THIS CONVECTION UN-ORGANIZED AND MAINLY NOT SEVERE. && .SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT) ISSUED AT 304 PM CDT SUN AUG 24 2014 THE MAIN CONCERN IS WITH THE RAIN CHANCES THROUGH THE PERIOD. SURFACE ANALYSIS THIS AFTERNOON SHOWS AN AREA OF LOW PRESSURE OVER NORTH DAKOTA WITH A COLD FRONT TRAILING SOUTH THROUGH WESTERN MINNESOTA INTO NEBRASKA. WATER VAPOR IMAGERY SHOWS A WOUND UP UPPER LEVEL LOW OVER EASTERN MONTANA THAT WAS LIFTING TO THE NORTHEAST. THE 24.12Z MODELS ARE ALL IN REASONABLY GOOD AGREEMENT WITH THE HANDLING OF THE UPPER LEVEL SYSTEM. IT WILL CONTINUE TO MOVE NORTHEAST REACHING WESTERN ONTARIO BY MONDAY EVENING. THE MAIN SHORT WAVE TROUGH WITH THIS SYSTEM IS VERY NEAR THE UPPER LEVEL LOW AND IS EXPECTED TO REMAIN THAT WAY. THIS TAKES THE PV ADVECTION IN THE 500-300 MB LAYER FROM EASTERN NORTH DAKOTA ACROSS NORTHWEST MINNESOTA INTO ONTARIO. THIS WILL TAKE THE BULK OF THE UPPER LEVEL FORCING WELL NORTH OF THE REGION BUT SOME UPPER LEVEL DIVERGENCE SHOULD SPREAD ACROSS THE AREA TONIGHT AS THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET MOVES OVER. AS THE FRONT MOVES IN TONIGHT...SOME WEAK FRONTOGENESIS SHOULD OCCUR IN THE 850-500 MB LAYER. GOOD LOW LEVEL WARM AIR ADVECTION AHEAD OF THE FRONT WILL HELP TO GENERATE 4 TO 6 UBAR/S OF UP GLIDE ON THE 310K ISENTROPIC SURFACE WITH THE MOISTURE TRANSPORT ON THIS SURFACE EXPECTED TO BE INTO THE AREA FROM LATE EVENING THROUGH THE OVERNIGHT HOURS. THE 24.12Z SOUNDING FROM KMPX SHOWS A STRONG CAP IS IN PLACE BETWEEN 850 AND 700 MB AND THE CONCERN BECOMES WHETHER THE FORCING WILL BE STRONG ENOUGH TO BREAK THE CAP. THE 24.12Z NAM BUFKIT SOUNDINGS SUGGEST THAT THE CAP MAY WEAKEN BUT NOT TOTALLY BREAK AND THIS IS REFLECTED IN THE MODEL ONLY PRODUCING SOME SCATTERED ACTIVITY ALONG THE FRONT AS IT COMES THROUGH. THE 24.12Z GFS AND ECMWF SHOW MUCH MORE QPF ALONG THE FRONT SUGGESTING THE CAP WILL BREAK. THE SHORT TERM MESO-MODELS ARE ABOUT AS EQUALLY SPLIT. THE 24.12Z HI-RES ARW LOOKS TO HOLD THE CAP IN PLACE WITH ALMOST NO ACTIVITY OVER THE AREA...WHILE THE HI-RES NMM IS CLOSER TO THE NAM WITH JUST SOME SCATTERED ACTIVITY. THE 24.12Z SPC WRF LOOKS TO DISSIPATE THE CAP AS EARLY AS LATE THIS AFTERNOON WITH LOTS OF CONVECTION DEVELOPING ACROSS MINNESOTA AND MOVING ACROSS THE AREA IN THE NIGHT. OUTPUT FROM THE 24.12Z HOP WRF IS ALSO SPLIT WITH A COUPLE OF MEMBERS DEVELOPING LOTS OF CONVECTION AND THE OTHER TWO STAYING WITH JUST SCATTERED ACTIVITY. IF THE CAP WOULD BREAK...THE BEST CHANCE FOR THIS TO OCCUR WOULD BE ACROSS THE NORTHERN SECTIONS OF THE FORECAST AREA CLOSER TO THE DYNAMIC FORCING AND WILL MAINTAIN THE LIKELY RAIN CHANCES ACROSS THAT AREA WHILE TAPERING DOWN TO 30 TO 40 PERCENT CHANCE ACROSS THE SOUTH. SOME THREAT OF SEVERE ACROSS THE NORTH AS WELL IF THE CAP CAN BREAK. PLENTY OF INSTABILITY WILL REMAIN IN PLACE AHEAD OF THE FRONT WITH THE NAM SHOWING 1000-1500 J/KG OF ML CAPE ALONG WITH 40 KNOTS OF 0-3KM SHEAR. DAMAGING WINDS AND HEAVY RAIN SHOULD BE THE MAIN THREATS AS WARM CLOUD DEPTHS WILL REMAIN IN THE 3.5 TO 4 KM RANGE AHEAD OF THE FRONT. MAY ALSO HAVE TO AWARE OF A SPIN UP TORNADO THREAT AS A DIFFERENTIAL HEATING BOUNDARY IS IN PLACE ON THE CLOUD EDGE. IF THIS BOUNDARY MAINTAINS ITSELF INTO THE EVENING...THE NAM INDICATES THE 0-1KM SHEAR WILL INCREASE TO AROUND 25 KNOTS. THE FRONT SHOULD THEN PASS THROUGH THE AREA MONDAY WITH THE POSSIBILITY OF SOME SCATTERED ACTIVITY ALONG IT. NOT MUCH FORCING ALONG THE FRONT BUT COULD SEE A DIURNAL INCREASE IN THE ACTIVITY DURING THE AFTERNOON WHEN THE ML CAPE SHOULD AGAIN BE IN THE 2000-3000 J/KG RANGE. THE MODELS THEN HAVE REALLY TRENDED TOWARD PUSHING THIS FRONT FARTHER SOUTH FROM MONDAY NIGHT INTO TUESDAY NIGHT AS THE HIGH PRESSURE BUILDING IN BEHIND IT IS MUCH STRONGER. MODELS CONTINUE TO SHOW A SHORT WAVE TROUGH MOVING ALONG THE UPPER LEVEL RIDGE AXIS AND INTERACTING WITH THE FRONT. IF THE FRONT DOES PUSH AS FAR SOUTH AS THE MODELS ARE CURRENTLY INDICATING...THIS WOULD PLACE THE HIGHEST RAIN CHANCES SOUTH OF THE IOWA/MINNESOTA BORDER. WILL MAINTAIN SOME 50 TO 60 PERCENT CHANCES FROM MONDAY NIGHT INTO TUESDAY NIGHT...BUT LIMIT THEM TO THE SOUTHERN SECTIONS. .LONG TERM...(WEDNESDAY THROUGH SUNDAY) ISSUED AT 304 PM CDT SUN AUG 24 2014 THE FRONT IS EXPECTED TO STILL NOT BE TOO FAR SOUTH OF THE AREA BY THE MIDDLE OF THE WEEK. THE 24.12Z ECMWF AND GFS IN DECENT AGREEMENT OF BRINGING ANOTHER SHORT WAVE TROUGH ACROSS THE TOP OF THE RIDGE AXIS WITH A SURFACE LOW MOVING ALONG THE FRONT. BASED ON THIS...WILL HAVE UP TO 50 PERCENT CHANCES ACROSS THE SOUTH FROM WEDNESDAY INTO THURSDAY NIGHT. THE RAIN CHANCES SHOULD THEN DIMINISH TO CLOSE OUT THE WEEK INTO THE WEEKEND AS HIGH PRESSURE BUILDS IN BEHIND THE MID WEEK SYSTEM. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 653 PM CDT SUN AUG 24 2014 THE MAIN FOCUS AT THE TAF SITES IS WITH THE CONVECTIVE TRENDS TONIGHT AS A COLD FRONT MOVES THROUGH THE REGION. A BATCH OF SHOWERS/STORMS HAS DEVELOPED IN NC IA/SC MN AND HAS BEEN TRACKING TO THE NORTHEAST AND WILL BE CLOSE TO RST. AFTER A BRIEF BREAK THIS EVENING...A SECOND ROUND OF CONVECTION IS POSSIBLE OVERNIGHT AND SHOULD BE A BIT MORE WIDESPREAD. THE MAIN PERIOD IT IS EXPECTED TO COME THROUGH RST WOULD BE BETWEEN 5-9Z AND LSE BETWEEN 8-11Z. SOME DROPS TO MVFR/IFR VISIBILITY WILL BE POSSIBLE IF THE SHOWERS/STORMS DO BECOME WIDESPREAD. WINDS WILL COME AROUND TO THE WEST TOMORROW AFTERNOON AS THE COLD FRONT PASSES THROUGH AND BRINGS AN END TO THE CHANCES FOR PRECIPITATION. && .HYDROLOGY... ISSUED AT 304 PM CDT SUN AUG 24 2014 HEAVY RAIN WILL BE A THREAT WITH ANY STORMS THAT DEVELOP TONIGHT. WARM CLOUD DEPTHS WILL BE IN THE 3.5 TO 4 KM RANGE WITH PRECIPITABLE WATERS APPROACHING TWO INCHES. THE CONCERN FOR HEAVY RAIN AND POSSIBLE FLOODING WITH THE STALLED FRONT FOR THE EARLY PART OF THE WEEK ARE DIMINISHING WITH THE FRONT EXPECTED TO PUSH FARTHER SOUTH. THE HIGHEST AXIS OF PRECIPITABLE WATERS SHOULD LAY UP SOUTH OF THE FRONT ACROSS SOUTHERN IOWA/NORTHERN MISSOURI INTO ILLINOIS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE...HALBACH SHORT TERM...04 LONG TERM...04 AVIATION...HALBACH HYDROLOGY...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
309 PM CDT SAT AUG 23 2014 .SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT) ISSUED AT 309 PM CDT SAT AUG 23 2014 SHORT TERM MAIN CONCERN IS INCREASING HEAT SUNDAY. WATER VAPOR/RAP 500MB ANALYSIS THIS AFTERNOON HAVE A MID-LEVEL SHORTWAVE AND ASSOCIATED BAND OF SHOWERS/THUNDERSTORMS PER RADAR MOSAIC ROTATING THROUGH SOUTHWEST WI/NORTHERN IL. CLOUD COVER AND SCATTERED PRECIPITATION KEEP TEMPERATURES IN THE 70S...BUT WITH VERY HUMID AIRMASS IN PLACE...FEELING MORE LIKE THE 80S. FOR TONIGHT...LOW PRESSURE MOVING NORTHEAST OUT OF THE CENTRAL HIGH PLAINS INTO THE NORTHERN PLAINS WILL DRAG A WARM FRONT NORTHWARD THROUGH THE REGION. STILL A CHANCE OF A FEW SHOWERS AND THUNDERSTORMS ALONG THE FRONTAL BOUNDARY...MAINLY ALONG/NORTHEAST OF I-94 AS EASTERN FLANK OF 850MB MOISTURE TRANSPORT IMPINGES UPON IT. OTHERWISE...WILL LIKELY SEE SOME STRATUS DEVELOPMENT TONIGHT IN MOIST SOUTHERLY FLOW. ANY DENSE FOG POTENTIAL LOOKS MINIMAL AT THIS POINT GIVEN STRENGTHENING SOUTHERLY FLOW TO KEEP THE LOWER BOUNDARY LAYER SOMEWHAT MIXED. LOOK FOR LOWS TONIGHT IN THE MID/UPPER 60S ACROSS CENTRAL WI...AND LOWER 70S ELSEWHERE. LOOKS LIKE THE HEAT IS ON FOR SUNDAY AS WE WILL BE IN THE WARM/CAPPED WARM SECTOR OF THE NORTHER PLAINS LOW. NAM STILL SHOWING 925MB TEMPERATURES IN THE 28-30C RANGE WEST OF THE MISSISSIPPI AND 25- 28C RANGE ACROSS THE EAST. AFTER SOME INITIAL MORNING STRATUS...EXPECTING SUNSHINE AND THIS HOT SOUTHERLY FLOW TO PUSH HIGHS INTO THE MID/UPPER 80S ACROSS CENTRAL WI...AND IN THE LOWER 90S IN THE WI RIVER VALLEY AND AREAS ALONG AND WEST OF THE MISSISSIPPI RIVER. WITH DEW POINTS IN THE 70-75 DEGREE RANGE...LOOKING AT HEAT INDICES IN THE 95 TO 105 DEGREE RANGE. AFTER COLLABORATION WITH SURROUNDING OFFICES AND CRITERIA CONSIDERATIONS...WILL HOLD OFF ON HEAT HEADLINE FOR NOW AND WILL CONTINUE TO CONVEY CONCERN VIA OUR HAZARDOUS WEATHER OUTLOOK AND WEATHER STORY/GRAPHIC PRODUCTS. A COLD FRONT WILL THEN PUSH INTO THE AREA SUNDAY NIGHT FOR THE LIKELIHOOD OF THUNDERSTORMS. CANNOT RULE OUT A SEVERE CHANCE GIVEN HIGHER CAPE ENVIRONMENT AND SUFFICIENT 0-3KM BULK SHEAR IN THE 20- 30KT RANGE. WILL HAVE TO KEEP A CLOSE EYE ON THIS. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 309 PM CDT SAT AUG 23 2014 MEDIUM RANGE MODELS REMAIN IN PRETTY GOOD AGREEMENT WITH FRONTAL BOUNDARY LINGERING ACROSS THE REGION THROUGH AT LEAST THURSDAY. MODELS SHOW SEVERAL MID-LEVEL IMPULSES WORKING ON THIS FRONTAL BOUNDARY FOR CONTINUED SHOWER/THUNDERSTORM CHANCES. WITH PRECIPITABLE WATER VALUES REMAINING IN THE 1.5-2 INCH RANGE...WILL HAVE TO KEEP AN EYE ON REPETITIVE CONVECTION POTENTIAL/POSSIBLE LOCALIZED FLOODING. OTHERWISE...WITH CLOUD COVER AND GOOD CHANCES OF SHOWERS AND STORMS...PLAN ON HIGH TEMPERATURES STARING OFF IN THE 80-90 DEGREE RANGE MONDAY...COOLING INTO THE LOWER/MIDDLE 70S BY THURSDAY. SOME TIMING DIFFERENCES THEN ARISE BETWEEN THE GFS AND ECMWF FOR FRIDAY AND SATURDAY. BOTH MODELS MOVE A MORE VIGOROUS MID-LEVEL TROUGH THE REGION. GFS IS MUCH FASTER/PROGRESSIVE WITH THIS FEATURE COMPERED TO THE ECMWF. AT THIS POINT...WILL TAKE A CONSENSUS APPROACH WHICH YIELDS SMALLER-END SHOWER/THUNDERSTORM CHANCES WITH HIGHS IN THE 70S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1201 PM CDT SAT AUG 23 2014 THE SHOWERS AND STORMS CONTINUE TO ADVANCE NORTHEAST ACROSS THE AREA BUT ARE NOW SHOWING A DIMINISHING TREND. EXPECT THAT THESE WILL BE PAST KRST BY 18Z BUT WILL LINGER INTO THE EARLY AFTERNOON WITH SOME MVFR CONDITIONS AT KLSE. ONCE THESE MOVE THROUGH...EXPECT THAT BOTH SITES WILL HAVE VFR CONDITIONS AS A WARM FRONT APPROACHES AND THEN MOVES THROUGH SWINGING THE WINDS AROUND TO THE SOUTHEAST. HOWEVER...NO DECREASE IN THE LOW LEVEL HUMIDITY LEVELS WILL OCCUR WHICH SHOULD PRESENT THE POSSIBILITY OF IFR CEILINGS WITH LOW STRATUS AGAIN TONIGHT. THE FORECAST SOUNDINGS FROM THE 23.12Z NAM AND 23.15Z RAP BOTH INDICATING THE STRATUS SHOULD FORM AND HAVE INCLUDED IT IN BOTH FORECASTS. NOT OVERLY CONCERNED ABOUT FOG FOR TONIGHT AS BOTH THE SURFACE WINDS AND WINDS JUST ABOVE THE SURFACE SHOULD BE TOO STRONG WITH TOO MIXING TO ALLOW IT TO FORM. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM....DAS AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1201 PM CDT SAT AUG 23 2014 .UPDATE... ISSUED AT 954 AM CDT SAT AUG 23 2014 BASED ON THE 23.12Z RAP...NOT REALLY EXPECTING THE COMPLEX OF SHOWERS AND STORMS TO DISSIPATE ANY TIME SOON. A SHORT WAVE TROUGH WILL CONTINUE TO SLOWLY MOVE NORTHEAST THROUGH THE AREA PROVIDING WEAK TO MODERATE PV ADVECTION IN THE 500-300 MB LAYER. IN THE LOW LEVELS...THE WARM FRONT WILL BE ADVANCING TOWARD THE AREA WITH WEAK FRONTOGENESIS IN THE 1000-850 MB LAYER THROUGH THE DAY. WARM AIR ADVECTION OVER THIS FRONT WILL PROVIDE 4 TO 6 UBAR/S OF UP GLIDE ON THE 310K ISENTROPIC SURFACE. THE MOISTURE TRANSPORT AT 850 MB SHOULD CONTINUE TO BE INTO AND OVER THE WARM FRONT. BASED ON ALL THIS...HAVE INCREASED THE RAIN CHANCES TO 80 PERCENT OR HIGHER FOR THE REMAINDER OF THE MORNING WEST OF THE MISSISSIPPI RIVER AND THEN ALLOWED FOR A SLOW WEAKENING TREND WHILE SPREADING THE RAIN CHANCES ACROSS MOST OF WISCONSIN DURING THE AFTERNOON. WILL LET THE DENSE FOG ADVISORY EXPIRE AS SCHEDULED AT 10 AM. MOST OF THE VISIBILITY HAS IMPROVED TO 2 MILES OR BETTER AND THE INCOMING RAIN SHOULD ALSO HELP TO CLEAN THE ATMOSPHERE UP A LITTLE BIT. UPDATE ISSUED AT 737 AM CDT SAT AUG 23 2014 A SHORT WAVE TROUGH CONTINUES TO MOVE NORTHEAST TOWARD THE FORECAST AREA THIS MORNING. THE HRRR SEEMS TO HAVE THE BEST HANDLE ON ITS PRECIPITATION...SO TRENDED THE FORECAST TOWARD IT. AS THE SYSTEM MOVES INTO OUR AREA THIS EXPECT TO SEE A GRADUAL SPLIT AS THE 850 TO 700 MB MOISTURE TRANSPORT BREAKS APART AND ONE PART GOES ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN...AND THE OTHER PIECE MOVES TO THE WEST OF OUR AREA. SO EXPECT THE AREA WHICH MOVES INTO SOUTHEAST MINNESOTA TO DISSPATE. MEANWHILE THE BETTER CHANCES OF PRECIPITATION WILL BE SOUTH OF INTERSTATE 90 AS THAT JET VEERS THROUGH THAT AREA. THERE MAY BE A REMNANT MCV THAT KEEPS SOME PRECIPITATION ACROSS WESTERN WISCONSIN THIS AFTERNOON. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 330 AM CDT SAT AUG 23 2014 SFC BOUNDARY LIES...MORE OR LESS...WEST EAST ACROSS SOUTHERN IA INTO CENTRAL ILL EARLY THIS MORNING. AN UPPER LEVEL TROUGH WILL LIFT NORTHEAST ACROSS THE NORTHERN PLAINS TODAY...AND SHOULD HELP GIVE THIS BOUNDARY A SHOVE NORTH. MEANWHILE...THERE ARE SUGGESTIONS IN THE MESO MODELS THAT AN MCV ASSOCIATED WITH THE CURRENT CONVECTION OVER NEB WOULD TAKE NORTHEAST TRACK TODAY...AND COULD SERVE AS A FOCUS FOR SHOWER/STORMS DEVELOP AS IT AND THE BOUNDARY SLIDE NORTH/NORTHEAST ACROSS THE REGION. HEAT AND HUMIDITY WILL ROUND OUT THE WEEKEND...AND HEAT ADVISORIES LOOK LIKELY FOR PORTIONS OF THE REGION. 850 MB SREF TEMP ANOMALIES AROUND +1.5 FOR SUNDAY WHILE 950 MB TEMPS ARE EXPECTED TO WARM TO 26- 28 C. HIGHS SHOULD REACH 90 ACROSS MUCH OF THE FORECAST AREA. ADD IN DEW POINTS IN THE LOWER 70S AND AFTERNOON HEAT INDICES SHOULD REACH 100 FOR A LARGE PORTION OF THE FORECAST AREA. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 330 AM CDT SAT AUG 23 2014 MODELS IN PRETTY GOOD AGREEMENT WITH THE OVERALL PATTERN THROUGH THE MIDDLE PART OF THE NEW WORK WEEK. SOLUTIONS SUGGEST AN UPPER LEVEL SHORTWAVE WILL TRACK OUT OF THE CENTRAL ROCKIES...ACROSS THE NORTHERN PLAINS AND INTO SOUTHERN CANADA SUNDAY NIGHT. ITS ASSOCIATED SFC COLD FRONT WILL DRAG ACROSS THE REGION LATE SUNDAY NIGHT INTO MONDAY...WITH THE SOUTHERN EXTENT LIKELY LINGERING IN A SOUTHWEST-NORTHEAST ORIENTATION OVER THE REGION. RIPPLES IN THE UPPER LEVEL FLOW WILL KICK OUT OF THE MEAN TROUGH...AND WORK ON THIS BOUNDARY MON-TUE. THIS NEXT TROUGH THEN SLIDES ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WED NIGHT/THU...CONTINUING TO WORK ON THAT SFC BOUNDARY...BUT ALSO PUSHING IT EAST/SOUTHEAST AS THE SYSTEM EXITS INTO THE EASTERN GREAT LAKES ON THU NIGHT. THERE ARE SOME DISCREPANCIES IN THE MODELS WITH PLACEMENT...TIMING AND STRENGTH OF THIS TROUGH...BUT THE TRENDS ARE SIMILAR AND ALL POINT TO SEVERAL DAYS WITH RAIN CHANCES. NOT OVERLY STRONG...BUT FAIRLY PERSISTENT FETCH OF 850 MB MOISTURE TRANSPORT INTO THE REGION FOR THE EARLY PART OF THE UPCOMING WEEK. WARM CLOUD DEPTHS CONTINUE TO HOVER NEAR 4 KFT WHILE PWS RANGE FROM 1.5 TO 1.75 INCHES. SO...HEAVY RAIN WOULD BE LIKELY WITH ANY THUNDERSTORMS...ESPECIALLY THE STRONGER ONES. AS FOR SEVERE POTENTIAL...AFTERNOON SBCAPES PROGGED FROM 2000-3000 J/KG PER THE GFS INTO WED...MOSTLY AROUND AND SOUTH OF THE SFC BOUNDARY. HOWEVER...WITH LOW/MID LEVEL WARMING PERSISTING...AND 700 MB TEMPS AROUND 10 C...THERE WILL BE A CAP TO DEAL WITH...AND SOME OF THIS LOW LEVEL INSTABILITY WILL NOT BE REALIZED. BUFKIT SOUNDINGS INDICATE THIS TOO. THE DEEPER...STRONGER SHEAR IS EXPECTED TO BE WELL INTO THE COLD AIR NORTH OF THE BOUNDARY...DISPLACED FROM THE STRONGER INSTABILITY. THERE IS SOME OVERLAP...SO SOME ENHANCED UPDRAFTS COULD BE SUPPORTED. OVERALL...NOT SURE THERE IS A TIME PERIOD THAT STANDS OUT FOR AN ORGANIZED SEVERE THREAT AT THIS TIME. THERE CERTAINLY COULD BE SOME SEVERE TO MARGINAL SEVERE STORMS...PERHAPS MORE PULSEY IN NATURE. MUCH DEPENDS ON BOUNDARY/SHORTWAVE INTERACTION AND TIME OF DAY. LOOK FOR UPDATES IN THE HWO FOR THE LATEST THOUGHTS ON THE DAY TO DAY SEVERE POTENTIAL. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1201 PM CDT SAT AUG 23 2014 THE SHOWERS AND STORMS CONTINUE TO ADVANCE NORTHEAST ACROSS THE AREA BUT ARE NOW SHOWING A DIMINISHING TREND. EXPECT THAT THESE WILL BE PAST KRST BY 18Z BUT WILL LINGER INTO THE EARLY AFTERNOON WITH SOME MVFR CONDITIONS AT KLSE. ONCE THESE MOVE THROUGH...EXPECT THAT BOTH SITES WILL HAVE VFR CONDITIONS AS A WARM FRONT APPROACHES AND THEN MOVES THROUGH SWINGING THE WINDS AROUND TO THE SOUTHEAST. HOWEVER...NO DECREASE IN THE LOW LEVEL HUMIDITY LEVELS WILL OCCUR WHICH SHOULD PRESENT THE POSSIBILITY OF IFR CEILINGS WITH LOW STRATUS AGAIN TONIGHT. THE FORECAST SOUNDINGS FROM THE 23.12Z NAM AND 23.15Z RAP BOTH INDICATING THE STRATUS SHOULD FORM AND HAVE INCLUDED IT IN BOTH FORECASTS. NOT OVERLY CONCERNED ABOUT FOG FOR TONIGHT AS BOTH THE SURFACE WINDS AND WINDS JUST ABOVE THE SURFACE SHOULD BE TOO STRONG WITH TOO MIXING TO ALLOW IT TO FORM. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE...04 SHORT TERM...RIECK LONG TERM....RIECK AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
954 AM CDT SAT AUG 23 2014 .UPDATE... ISSUED AT 954 AM CDT SAT AUG 23 2014 BASED ON THE 23.12Z RAP...NOT REALLY EXPECTING THE COMPLEX OF SHOWERS AND STORMS TO DISSIPATE ANY TIME SOON. A SHORT WAVE TROUGH WILL CONTINUE TO SLOWLY MOVE NORTHEAST THROUGH THE AREA PROVIDING WEAK TO MODERATE PV ADVECTION IN THE 500-300 MB LAYER. IN THE LOW LEVELS...THE WARM FRONT WILL BE ADVANCING TOWARD THE AREA WITH WEAK FRONTOGENESIS IN THE 1000-850 MB LAYER THROUGH THE DAY. WARM AIR ADVECTION OVER THIS FRONT WILL PROVIDE 4 TO 6 UBAR/S OF UP GLIDE ON THE 310K ISENTROPIC SURFACE. THE MOISTURE TRANSPORT AT 850 MB SHOULD CONTINUE TO BE INTO AND OVER THE WARM FRONT. BASED ON ALL THIS...HAVE INCREASED THE RAIN CHANCES TO 80 PERCENT OR HIGHER FOR THE REMAINDER OF THE MORNING WEST OF THE MISSISSIPPI RIVER AND THEN ALLOWED FOR A SLOW WEAKENING TREND WHILE SPREADING THE RAIN CHANCES ACROSS MOST OF WISCONSIN DURING THE AFTERNOON. WILL LET THE DENSE FOG ADVISORY EXPIRE AS SCHEDULED AT 10 AM. MOST OF THE VISIBILITY HAS IMPROVED TO 2 MILES OR BETTER AND THE INCOMING RAIN SHOULD ALSO HELP TO CLEAN THE ATMOSPHERE UP A LITTLE BIT. UPDATE ISSUED AT 737 AM CDT SAT AUG 23 2014 A SHORT WAVE TROUGH CONTINUES TO MOVE NORTHEAST TOWARD THE FORECAST AREA THIS MORNING. THE HRRR SEEMS TO HAVE THE BEST HANDLE ON ITS PRECIPITATION...SO TRENDED THE FORECAST TOWARD IT. AS THE SYSTEM MOVES INTO OUR AREA THIS EXPECT TO SEE A GRADUAL SPLIT AS THE 850 TO 700 MB MOISTURE TRANSPORT BREAKS APART AND ONE PART GOES ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN...AND THE OTHER PIECE MOVES TO THE WEST OF OUR AREA. SO EXPECT THE AREA WHICH MOVES INTO SOUTHEAST MINNESOTA TO DISSPATE. MEANWHILE THE BETTER CHANCES OF PRECIPITATION WILL BE SOUTH OF INTERSTATE 90 AS THAT JET VEERS THROUGH THAT AREA. THERE MAY BE A REMNANT MCV THAT KEEPS SOME PRECIPITATION ACROSS WESTERN WISCONSIN THIS AFTERNOON. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 330 AM CDT SAT AUG 23 2014 SFC BOUNDARY LIES...MORE OR LESS...WEST EAST ACROSS SOUTHERN IA INTO CENTRAL ILL EARLY THIS MORNING. AN UPPER LEVEL TROUGH WILL LIFT NORTHEAST ACROSS THE NORTHERN PLAINS TODAY...AND SHOULD HELP GIVE THIS BOUNDARY A SHOVE NORTH. MEANWHILE...THERE ARE SUGGESTIONS IN THE MESO MODELS THAT AN MCV ASSOCIATED WITH THE CURRENT CONVECTION OVER NEB WOULD TAKE NORTHEAST TRACK TODAY...AND COULD SERVE AS A FOCUS FOR SHOWER/STORMS DEVELOP AS IT AND THE BOUNDARY SLIDE NORTH/NORTHEAST ACROSS THE REGION. HEAT AND HUMIDITY WILL ROUND OUT THE WEEKEND...AND HEAT ADVISORIES LOOK LIKELY FOR PORTIONS OF THE REGION. 850 MB SREF TEMP ANOMALIES AROUND +1.5 FOR SUNDAY WHILE 950 MB TEMPS ARE EXPECTED TO WARM TO 26- 28 C. HIGHS SHOULD REACH 90 ACROSS MUCH OF THE FORECAST AREA. ADD IN DEW POINTS IN THE LOWER 70S AND AFTERNOON HEAT INDICES SHOULD REACH 100 FOR A LARGE PORTION OF THE FORECAST AREA. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 330 AM CDT SAT AUG 23 2014 MODELS IN PRETTY GOOD AGREEMENT WITH THE OVERALL PATTERN THROUGH THE MIDDLE PART OF THE NEW WORK WEEK. SOLUTIONS SUGGEST AN UPPER LEVEL SHORTWAVE WILL TRACK OUT OF THE CENTRAL ROCKIES...ACROSS THE NORTHERN PLAINS AND INTO SOUTHERN CANADA SUNDAY NIGHT. ITS ASSOCIATED SFC COLD FRONT WILL DRAG ACROSS THE REGION LATE SUNDAY NIGHT INTO MONDAY...WITH THE SOUTHERN EXTENT LIKELY LINGERING IN A SOUTHWEST-NORTHEAST ORIENTATION OVER THE REGION. RIPPLES IN THE UPPER LEVEL FLOW WILL KICK OUT OF THE MEAN TROUGH...AND WORK ON THIS BOUNDARY MON-TUE. THIS NEXT TROUGH THEN SLIDES ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WED NIGHT/THU...CONTINUING TO WORK ON THAT SFC BOUNDARY...BUT ALSO PUSHING IT EAST/SOUTHEAST AS THE SYSTEM EXITS INTO THE EASTERN GREAT LAKES ON THU NIGHT. THERE ARE SOME DISCREPANCIES IN THE MODELS WITH PLACEMENT...TIMING AND STRENGTH OF THIS TROUGH...BUT THE TRENDS ARE SIMILAR AND ALL POINT TO SEVERAL DAYS WITH RAIN CHANCES. NOT OVERLY STRONG...BUT FAIRLY PERSISTENT FETCH OF 850 MB MOISTURE TRANSPORT INTO THE REGION FOR THE EARLY PART OF THE UPCOMING WEEK. WARM CLOUD DEPTHS CONTINUE TO HOVER NEAR 4 KFT WHILE PWS RANGE FROM 1.5 TO 1.75 INCHES. SO...HEAVY RAIN WOULD BE LIKELY WITH ANY THUNDERSTORMS...ESPECIALLY THE STRONGER ONES. AS FOR SEVERE POTENTIAL...AFTERNOON SBCAPES PROGGED FROM 2000-3000 J/KG PER THE GFS INTO WED...MOSTLY AROUND AND SOUTH OF THE SFC BOUNDARY. HOWEVER...WITH LOW/MID LEVEL WARMING PERSISTING...AND 700 MB TEMPS AROUND 10 C...THERE WILL BE A CAP TO DEAL WITH...AND SOME OF THIS LOW LEVEL INSTABILITY WILL NOT BE REALIZED. BUFKIT SOUNDINGS INDICATE THIS TOO. THE DEEPER...STRONGER SHEAR IS EXPECTED TO BE WELL INTO THE COLD AIR NORTH OF THE BOUNDARY...DISPLACED FROM THE STRONGER INSTABILITY. THERE IS SOME OVERLAP...SO SOME ENHANCED UPDRAFTS COULD BE SUPPORTED. OVERALL...NOT SURE THERE IS A TIME PERIOD THAT STANDS OUT FOR AN ORGANIZED SEVERE THREAT AT THIS TIME. THERE CERTAINLY COULD BE SOME SEVERE TO MARGINAL SEVERE STORMS...PERHAPS MORE PULSEY IN NATURE. MUCH DEPENDS ON BOUNDARY/SHORTWAVE INTERACTION AND TIME OF DAY. LOOK FOR UPDATES IN THE HWO FOR THE LATEST THOUGHTS ON THE DAY TO DAY SEVERE POTENTIAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 737 AM CDT SAT AUG 23 2014 KLSE WILL KEEP THE IFR STRATUS DECK THROUGH 23.13Z...AND THEN IT WILL SLOWLY RISE BECOMING MVFR BY 23.15Z AND VFR BY 23.19Z. WITH THE LINE OF CONVECTION EXPECTED TO SHEAR APART BEFORE REACHING KLSE WENT DRY FOR NOW. THE DENSE FOG AT KRST WILL GRADUALLY LIFT INTO A IFR/MVFR DECK BY 23.15Z...AND THEN THE CEILINGS WILL BECOME MVFR AND REMAIN THAT WAY THROUGH 24.00Z. IT DOES NOT LOOK THE BAND OF SHOWERS WILL BREAK UP PRIOR TO REACHING KRST...SO INCLUDED VICINITY SHOWERS BETWEEN 23.17Z AND 23.19Z. VFR CONTIONS ARE CONDITIONS ARE EXEPCTED AT BOTH SITES THIS EVENING...AND THEN THE MODELS SUGGEST DENSE FOG AGAIN. HOWEVER LOOKING AT THE WIND IN THE SOUNDINGS NOT BUYING INTO THIS...SO JUST KEPT THINGS VFR. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE...04 SHORT TERM...RIECK LONG TERM....RIECK AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
738 AM CDT SAT AUG 23 2014 .UPDATE... ISSUED AT 737 AM CDT SAT AUG 23 2014 A SHORT WAVE TROUGH CONTINUES TO MOVE NORTHEAST TOWARD THE FORECAST AREA THIS MORNING. THE HRRR SEEMS TO HAVE THE BEST HANDLE ON ITS PRECIPITATION...SO TRENDED THE FORECAST TOWARD IT. AS THE SYSTEM MOVES INTO OUR AREA THIS EXPECT TO SEE A GRADUAL SPLIT AS THE 850 TO 700 MB MOISTURE TRANSPORT BREAKS APART AND ONE PART GOES ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN...AND THE OTHER PIECE MOVES TO THE WEST OF OUR AREA. SO EXPECT THE AREA WHICH MOVES INTO SOUTHEAST MINNESOTA TO DISSPATE. MEANWHILE THE BETTER CHANCES OF PRECIPITATION WILL BE SOUTH OF INTERSTATE 90 AS THAT JET VEERS THROUGH THAT AREA. THERE MAY BE A REMNANT MCV THAT KEEPS SOME PRECIPITATION ACROSS WESTERN WISCONSIN THIS AFTERNOON. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 330 AM CDT SAT AUG 23 2014 SFC BOUNDARY LIES...MORE OR LESS...WEST EAST ACROSS SOUTHERN IA INTO CENTRAL ILL EARLY THIS MORNING. AN UPPER LEVEL TROUGH WILL LIFT NORTHEAST ACROSS THE NORTHERN PLAINS TODAY...AND SHOULD HELP GIVE THIS BOUNDARY A SHOVE NORTH. MEANWHILE...THERE ARE SUGGESTIONS IN THE MESO MODELS THAT AN MCV ASSOCIATED WITH THE CURRENT CONVECTION OVER NEB WOULD TAKE NORTHEAST TRACK TODAY...AND COULD SERVE AS A FOCUS FOR SHOWER/STORMS DEVELOP AS IT AND THE BOUNDARY SLIDE NORTH/NORTHEAST ACROSS THE REGION. HEAT AND HUMIDITY WILL ROUND OUT THE WEEKEND...AND HEAT ADVISORIES LOOK LIKELY FOR PORTIONS OF THE REGION. 850 MB SREF TEMP ANOMALIES AROUND +1.5 FOR SUNDAY WHILE 950 MB TEMPS ARE EXPECTED TO WARM TO 26- 28 C. HIGHS SHOULD REACH 90 ACROSS MUCH OF THE FORECAST AREA. ADD IN DEW POINTS IN THE LOWER 70S AND AFTERNOON HEAT INDICES SHOULD REACH 100 FOR A LARGE PORTION OF THE FORECAST AREA. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 330 AM CDT SAT AUG 23 2014 MODELS IN PRETTY GOOD AGREEMENT WITH THE OVERALL PATTERN THROUGH THE MIDDLE PART OF THE NEW WORK WEEK. SOLUTIONS SUGGEST AN UPPER LEVEL SHORTWAVE WILL TRACK OUT OF THE CENTRAL ROCKIES...ACROSS THE NORTHERN PLAINS AND INTO SOUTHERN CANADA SUNDAY NIGHT. ITS ASSOCIATED SFC COLD FRONT WILL DRAG ACROSS THE REGION LATE SUNDAY NIGHT INTO MONDAY...WITH THE SOUTHERN EXTENT LIKELY LINGERING IN A SOUTHWEST-NORTHEAST ORIENTATION OVER THE REGION. RIPPLES IN THE UPPER LEVEL FLOW WILL KICK OUT OF THE MEAN TROUGH...AND WORK ON THIS BOUNDARY MON-TUE. THIS NEXT TROUGH THEN SLIDES ACROSS THE UPPER MISSISSIPPI RIVER VALLEY WED NIGHT/THU...CONTINUING TO WORK ON THAT SFC BOUNDARY...BUT ALSO PUSHING IT EAST/SOUTHEAST AS THE SYSTEM EXITS INTO THE EASTERN GREAT LAKES ON THU NIGHT. THERE ARE SOME DISCREPANCIES IN THE MODELS WITH PLACEMENT...TIMING AND STRENGTH OF THIS TROUGH...BUT THE TRENDS ARE SIMILAR AND ALL POINT TO SEVERAL DAYS WITH RAIN CHANCES. NOT OVERLY STRONG...BUT FAIRLY PERSISTENT FETCH OF 850 MB MOISTURE TRANSPORT INTO THE REGION FOR THE EARLY PART OF THE UPCOMING WEEK. WARM CLOUD DEPTHS CONTINUE TO HOVER NEAR 4 KFT WHILE PWS RANGE FROM 1.5 TO 1.75 INCHES. SO...HEAVY RAIN WOULD BE LIKELY WITH ANY THUNDERSTORMS...ESPECIALLY THE STRONGER ONES. AS FOR SEVERE POTENTIAL...AFTERNOON SBCAPES PROGGED FROM 2000-3000 J/KG PER THE GFS INTO WED...MOSTLY AROUND AND SOUTH OF THE SFC BOUNDARY. HOWEVER...WITH LOW/MID LEVEL WARMING PERSISTING...AND 700 MB TEMPS AROUND 10 C...THERE WILL BE A CAP TO DEAL WITH...AND SOME OF THIS LOW LEVEL INSTABILITY WILL NOT BE REALIZED. BUFKIT SOUNDINGS INDICATE THIS TOO. THE DEEPER...STRONGER SHEAR IS EXPECTED TO BE WELL INTO THE COLD AIR NORTH OF THE BOUNDARY...DISPLACED FROM THE STRONGER INSTABILITY. THERE IS SOME OVERLAP...SO SOME ENHANCED UPDRAFTS COULD BE SUPPORTED. OVERALL...NOT SURE THERE IS A TIME PERIOD THAT STANDS OUT FOR AN ORGANIZED SEVERE THREAT AT THIS TIME. THERE CERTAINLY COULD BE SOME SEVERE TO MARGINAL SEVERE STORMS...PERHAPS MORE PULSEY IN NATURE. MUCH DEPENDS ON BOUNDARY/SHORTWAVE INTERACTION AND TIME OF DAY. LOOK FOR UPDATES IN THE HWO FOR THE LATEST THOUGHTS ON THE DAY TO DAY SEVERE POTENTIAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 737 AM CDT SAT AUG 23 2014 KLSE WILL KEEP THE IFR STRATUS DECK THROUGH 23.13Z...AND THEN IT WILL SLOWLY RISE BECOMING MVFR BY 23.15Z AND VFR BY 23.19Z. WITH THE LINE OF CONVECTION EXPECTED TO SHEAR APART BEFORE REACHING KLSE WENT DRY FOR NOW. THE DENSE FOG AT KRST WILL GRADUALLY LIFT INTO A IFR/MVFR DECK BY 23.15Z...AND THEN THE CEILINGS WILL BECOME MVFR AND REMAIN THAT WAY THROUGH 24.00Z. IT DOES NOT LOOK THE BAND OF SHOWERS WILL BREAK UP PRIOR TO REACHING KRST...SO INCLUDED VICINITY SHOWERS BETWEEN 23.17Z AND 23.19Z. VFR CONTIONS ARE CONDITIONS ARE EXEPCTED AT BOTH SITES THIS EVENING...AND THEN THE MODELS SUGGEST DENSE FOG AGAIN. HOWEVER LOOKING AT THE WIND IN THE SOUNDINGS NOT BUYING INTO THIS...SO JUST KEPT THINGS VFR. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR WIZ017-029- 032>034-041>044-053>055-061. MN...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR MNZ079- 086>088-094>096. IA...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR IAZ010-011- 030. && $$ UPDATE...BOYNE SHORT TERM...RIECK LONG TERM....RIECK AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1102 PM MDT FRI AUG 22 2014 .UPDATE... ISSUED AT 807 PM MDT FRI AUG 22 2014 A PRONOUNCED MIDLVL SHORTWAVE CONTINUES TO LIFT NORTHEAST ACROSS CENTRAL CO THIS EVENING PER RECENT WATER VAPOR IMAGERY. REGIONAL RADAR MOSAIC SHOWS A BAND OF MODERATE RAIN AND EMBEDDED TSTMS HAS DEVELOPED OVER THE WESTERN NE PANHANDLE...LIKELY SUPPORTED BY A MESOSCALE VORTEX CURRENTLY IN THE VICINITY OF AKO. THIS AREA OF PCPN IS EXPECTED TO SHIFT NORTH AND EAST WITH TIME...SO HAVE THE CATEGORICAL POPS CONFINED TO AREAS ALONG AND SOUTHEAST OF A LINE FROM IBM TO SNY IN OUR CWA. PCPN INTENSITY SHOULD NOT BE PARTICULARLY HEAVY TONIGHT AS INSTABILITY WAS MITIGATED BY EXTENSIVE CLOUD COVER EARLIER TODAY. THINKING ANY THREAT FOR FLASH FLOODING IS RATHER LOW. NOT SURE HOW WIDESPREAD CONVECTION WILL BE ELSEWHERE...BUT ENOUGH MOISTURE IN MONSOONAL FLOW COMBINED WITH LARGER SCALE SUPPORT SUGGESTS A CONTINUED THREAT FOR ISOLATED TO SCATTERED SHOWERS FOR MOST OF THE NIGHT. FOG COULD BE A CONCERN TONIGHT...AND WEBCAMS HAVE ALREADY SHOWN THIS IN THE LARAMIE RANGE FOOTHILLS. DO NOT THINK THIS WILL LAST LONG AS ALL MODEL GUIDANCE SHOWS LLVL WINDS SHIFTING TO THE SOUTHWEST. FARTHER E...TRUE FOG IS UNLIKELY WITH MODERATE PCPN. OPTED NOT TO INCLUDE IN THE GRIDS ATTM BUT WILL CONTINUE TO MONITOR. ONLY OTHER CHANGE TO THE FCST WAS TO BUMP LOW TEMPS UP A FEW DEGREES WHERE THE MAIN PCPN BAND IS SETTING UP. DO NOT EXPECT MUCH FOR RADIATIONAL COOLING THERE. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 300 PM MDT FRI AUG 22 2014 PRETTY ACTIVE THE NEXT 24 TO 48 HOURS. TEMPERATURES AND POPS ARE THE FORECAST CHALLENGES FOR THE SHORT TERM. CURRENTLY...WATER VAPOR IMAGERY SHOWING A PRETTY PRONOUNCED WAVE IN THE MONSOONAL FLOW MOVING NORTH THIS AFTERNOON OUT OF NEW MEXICO INTO WEST CENTRAL COLORADO. MOSAIC RADAR SHOWING WIDESPREAD SHOWERS OVER CENTRAL COLORADO EARLY THIS AFTERNOON WITH A GENERAL NORTH NORTHEAST MOVEMENT ON THE CELLS. INFRARED RADAR SHOWING COOLING CLOUD TOPS WITH THIS WAVE AND WE ARE SEEING AN UPTICK IN LIGHTNING STRIKES ACROSS WESTERN COLORADO. UPPER LOW OVER IDAHO FAIRLY DYNAMIC AS WELL WITH NUMEROUS LIGHTNING STRIKES DEVELOPING. LATEST SPC MESOANALYSIS SHOWING A SLOW EROSION OF CIN OVER EXTREME SOUTHEAST WYOMING INTO THE KIMBALL AREA...WITH CAPE VALUES AROUND 1000 J/KG ABOVE. LOOKING AT CLOUD COVER OVERHEAD...IT IS PRETTY DENSE AND WE HAVE BEEN HARD PRESSED TO GET MUCH WARMING SO FAR TODAY. 1 PM TEMPERATURES HERE AT THE OFFICE AT 69 DEGREES WITH LOW TO MID 70S OUT IN THE PANHANDLE. FOR THIS EVENING...SHORTWAVE BEGINS TO MOVE INTO SOUTHEAST WYOMING SHORTLY AFTER 00Z WITH GUIDANCE INDICATING FAIRLY WIDESPREAD CONVECTION DEVELOPING AS THIS HAPPENS. THE 16Z HRRR FORECAST HAS CONVECTION DEVELOPING HERE AT CHEYENNE AROUND THE 22Z TIME FRAME...THEN EXPANDING ACROSS SOUTHERN WYOMING INTO THE PANHANDLE AFTER WARDS. BY 01Z...MOST LOCATIONS EAST OF THE LARAMIE RANGE SHOULD BE SEEING MEASURABLE RAINFALL WITH SCATTERED SHOWERS OUT WEST. NAM SOUNDINGS FOR THE PANHANDLE SHOWING PRETTY STRONG SHEAR OUT IN THE PANHANDLE THIS EVENING. LOOKING AT EASTERLY WINDS NEAR THE SURFACE OF 15 TO 20KTS WITH SOUTHWEST 40-45KTS AT 6KM. EVENING SHIFT WILL DEFINITELY NEED TO BE WATCHING FOR SEVERE THUNDERSTORMS. 0-3KM HELICITY FOR SIDNEY AT 386M2/S2 AT 00Z. GIVEN THE THICK CLOUD COVER THOUGH...CHANCES ARE DIMMING THAT WE WILL SEE SEVERE THUNDERSTORMS. SOMETHING ELSE FOR THIS AFTN/EVE...PRECIPITABLE WATER VALUES REALLY HIGH FOR THE PANHANDLE. SIDNEY SOUNDING SHOWING 1.42 INCHES...EXTENDING UP TO CHADRON AT 1.40 INCHES. FORECAST QPF REALLY HIGH FOR THE PANHANDLE AND EXTREME EASTERN WYOMING TONIGHT. GOOD NEWS IS FORECAST STORM MOTIONS ARE FROM THE SOUTHWEST AT 14-16KTS...SO THESE STORMS SHOULD BE MOVING FAIRLY FAST. WILL NEED TO WATCH THOUGH FOR TRAINING THUNDERSTORMS AND THERE COULD BE SOME FLASH FLOODING FOR SOME AREAS THIS EVENING. GFS AND ECMWF HAVE COME INTO DECENT AGREEMENT WITH THE UPSTREAM LOW ON THIS 12Z RUN. BOTH SHOWING THE CLOSED LOW MOVING PRETTY SLOW THROUGH NORTHERN WYOMING THROUGH THE DAY SATURDAY. MOST OF SATURDAY WILL SEE SHOWERS LASTING MOST OF THE DAY. WENT SIGNIFICANTLY HIGHER ON POPS OVER GUIDANCE. DO BELIEVE THE MID SHIFT WILL PROBABLY WANT TO GO HIGHER. FINALLY SATURDAY EVENING...THE UPPER LOW MOVES OFF INTO SOUTH DAKOTA WITH RAIN ENDING FROM WEST TO EAST. GOING TO BE PRETTY COOL WITH 700MB TEMPERATURES DOWN TO +6C SATURDAY NIGHT. SHOULD SEE WIDESPREAD 40S OUT WEST FOR LOWS...WITH LOW 50S EAST. CLOUD COVER COULD PROVIDE SLIGHTLY WARMER TEMPERATURES...WE WILL HAVE TO SEE AS THE EVENT GETS CLOSER. DID GO UNDER GUIDANCE FOR SUNDAY LOWS...ESPECIALLY OUT WEST WHERE CLOUD COVER WOULD BE LESS. .LONG TERM...(MONDAY THROUGH FRIDAY) ISSUED AT 335 PM MDT FRI AUG 22 2014 MEDIUM RANGE MODELS IN GOOD AGREEMENT THROUGH EARLY TUESDAY...BUT THEN SOLUTIONS BEGIN TO DIVERGE THROUGH WEDNESDAY...WITH POOR CONSISTENCY BETWEEN THE 12Z AND 00Z MODEL RUNS APPARENT INTO LATE NEXT WEEK. EARLY IN THE WEEK...MOIST SOUTHWEST FLOW AHEAD OF A POSITIVELY TILTED UPPER LEVEL TROUGH WILL MOVE ACROSS ACROSS THE IDAHO AND INTO WESTERN WYOMING. A WEAK BOUNDARY WILL DEVELOP AND DRIFT WESTWARD ALONG THE LARAMIE RANGE...WHICH WILL RESULT IN UPSLOPE FLOW AND ENHANCE LIFT ACROSS THE HIGH PLAINS. KEPT POP BETWEEN 35 TO 60 PERCENT ACROSS THE AREA WITH A GOOD CHANCE OF AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS. ALL MODELS SHOW THIS ACTIVITY LINGERING THROUGH MONDAY NIGHT AS WELL AS A WAVE OF LOW PRESSURE DEVELOPS ALONG THE BOUNDARY...WHICH WILL EVENTUALLY TRANSITION INTO A COLD FRONT. KEPT POP AROUND 50 PERCENT MONDAY NIGHT. WILL HAVE TO WATCH FOR STRONG TO SEVERE THUNDERSTORMS MONDAY EVENING WITH CAPE VALUES AROUND 1500 TO 2000 J/KG...HIGH PW/S...AND INSTABILITY. ECMWF STILL TRENDING SLOWER WITH THE UPPER LEVEL TROUGH COMPARED TO THE GFS. THE GEM HAS TRENDED TOWARDS THE ECMWF WHILE THE GFS PUSHES THE TROUGH THROUGH THE FORECAST AREA AS EARLY AS TUESDAY AFTERNOON. THE ECMWF AND GEM SHOW THE TROUGH AXIS MOVING ACROSS THE AREA LATE TUESDAY NIGHT AND EARLY WEDNESDAY. THE GEM AND ECMWF SOLUTIONS THEN DIVERGE WITH THE ECMWF SHOWING THE SYSTEM ATTEMPTING TO CLOSE OFF ON WEDNESDAY. EITHER WAY...EXPECT TUESDAY AND TUESDAY EVENING TO REMAIN UNSETTLED WITH COOLER THAN NORMAL TEMPERATURES AND A GOOD CHANCE OF WIDESPREAD RAINFALL. HIGHS MAY STRUGGLE TO REACH THE MID TO UPPER 60S ON TUESDAY AS 700MB TEMPERATURES LOWER BELOW 5C AFTER THE FRONT MOVES THROUGH THE AREA. LOW CONFIDENCE ON THE WEDNESDAY FORECAST DUE TO SIGNIFICANT MODEL DIFFERENCES. KEPT A SLIGHT CHANCE OF SHOWERS AND TSTORMS FOR NOW DUE TO TIMING DIFFERENCES...EVEN THOUGH THE ECMWF SOLUTION IS UNLIKELY TO OCCUR. MUCH DRIER AIR MOVES INTO THE REGION THURSDAY AND FRIDAY BASED ON CURRENT MODEL RUNS AS THE RIDGE AXIS REDEVELOPS WEST OF THE ROCKY MOUNTAINS AND DRIFTS EASTWARD. BASED ON 12Z MODELS...WARMER TEMPERATURES AND DRY CONDITIONS ARE EXPECTED NEXT WEEK. HOWEVER...THERE IS A LARGE CONTRAST BETWEEN THESE SOLUTIONS AND THE PREVIOUS 00Z SOLUTIONS FROM LAST NIGHT WHICH SHOW A PACIFIC SYSTEM MOVES INTO THE REGION WITH ANOTHER STRONG COLD FRONT ENTERING WYOMING BY LATE FRIDAY. KEPT TEMPERATURES NEAR NORMAL FOR NOW WITH POP BELOW 10 PERCENT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY EVENING) ISSUED AT 1059 PM MDT FRI AUG 22 2014 IFR CIGS WILL OCCUR OVER PORTIONS OF SOUTHEAST WYOMING AND MUCH OF THE NEBRASKA PANHANDLE TONIGHT. FOG IS ALSO EXPECTED LATE TONIGHT THROUGH MID MORNING SATURDAY WITH POCKETS SOME LIFR. ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS EXPECTED FOR SATURDAY AFTERNOON AND EVENING. && .FIRE WEATHER... ISSUED AT 300 PM MDT FRI AUG 22 2014 MINIMAL FIRE WEATHER CONCERNS ACROSS THE AREA THROUGH THE NEXT FEW DAYS. UPPER LOW PRESSURE OVER IDAHO THIS AFTERNOON WILL BRING INCREASING MONSOONAL MOISTURE AND FAIRLY WIDESPREAD RAINFALL TO MUCH OF THE AREA TONIGHT INTO SATURDAY. BEST CHANCES FOR WETTING RAINS WILL BE ALONG AND EAST OF THE LARAMIE RANGE AS WELL AS THE SNOWY AND SIERRA MADRE RANGES. THE UPPER LOW WILL GRADUALLY MOVE INTO WESTERN SOUTH DAKOTA EARLY SUNDAY MORNING WITH RAINS ENDING FROM WEST TO EAST. COOLER TEMPERATURES BEHIND THE LOW WILL KEEP AFTERNOON HUMIDITIES FAIRLY HIGH WITH EXCELLENT OVERNIGHT && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ UPDATE...HAMMER SHORT TERM...CLAYCOMB LONG TERM...TJT AVIATION...SML FIRE WEATHER...CLAYCOMB
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
151 AM MDT MON AUG 25 2014 .UPDATE... ISSUED AT 146 AM MDT MON AUG 25 2014 QUICK UPDATE TO BOOST POPS ACROSS THE CENTRAL ZONES AS ACTIVITY DEVELOPS ALONG OUTFLOW BOUNDARIES AND EDGE OF DEEPER SHEER TO THE NORTH. NO OTHER CHANGES ATTM WITH NEW GRIDS OUT SHORTLY. UPDATE ISSUED AT 1036 PM MDT SUN AUG 24 2014 CONVECTION CONTINUES TO EXPAND IN AREAL COVERAGE ALONG AND NORTH OF UPPER LEVEL JET LIFTING NORTHEAST ACROSS THE FORECAST AREA LATE THIS EVENING. FEW STRONGER CELLS DEVELOPING WITH NUMEROUS OUTFLOW BOUNDARIES KICKING UP STRONGER SFC WINDS. LATEST HRRR RUNS INDICATE THIS WILL CONTINUE THROUGH THE REMAINDER OF THE NIGHT AND HAVE MADE SIGNIFICANT ADJUSTMENTS TO POPS GRIDS TO FIT CURRENT TRENDS AND EXPECTED CONDITIONS FOR THE REMAINDER OF THE NIGHT. OUTFLOW GUSTS TO 40 MPH POSSIBLE TONIGHT ALONG WITH SMALL HAIL NEAR THE STRONGER CELLS. OTHERWISE...MORE MUCH NEEDED RAIN FOR THE NORTHERN PORTIONS OF OUR FORECAST AREA. UPDATE ISSUED AT 550 PM MDT SUN AUG 24 2014 SHORT TERM UPDATE WILL BE REQUIRED EARLY THIS EVENING AS CONVECTION HAS INCREASED ACROSS EAST CENTRAL UTAH. THIS ACTIVITY MAY EXPAND INTO NW COLORADO...POSSIBLY AS FAR AS A LINE FROM MOAB TO ASPEN. THIS ACTIVITY IS IN RESPONSE TO EMBEDDED DISTURBANCE ALONG A SHEAR AXIS THAT CUTS ACROSS THE FORECAST AREA THIS EVENING. RAP AND HRRR MODELS INDICATE THAT SHOWERS AND STORMS LASTING WELL BEYOND SUNSET WILL OCCUR FROM VERNAL TO ROUTT COUNTY. IT APPEARS THAT THE LOWER RESOLUTION SUCH AS THE GFS40 IS SUGGESTING NOCTURNAL CONVECTION AS WELL. UPDATE WILL BE COMING AND WILL BE LEANING TOWARDS THE RAP/HRRR MODELS. && .SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT) ISSUED AT 255 PM MDT SUN AUG 24 2014 12Z H5 HAND ANALYSIS SHOWING A BLOCKING RIDGE EXTENDING FROM THE GULF STATES UP INTO THE CANADIAN MARITIME REGION. AS SUCH LOW PRESSURE WILL BE ANCHORING IN THE WESTERN STATES TO START OUT THE NEW WEEK. THE MORE IMPRESSIVE FEATURES SHOWING UP IN WATER VAPOR THIS AFTERNOON ARE THE PAIR OF LOWS ROTATING AROUND EACH OTHER OVER MONTANA AND WASHINGTON THIS AFTERNOON. THE FORMER RETREATING NORTHEASTWARD AND THE LATTER DROPPING SOUTHWARD WHERE IT WILL CARVE OUT A FAIRLY AMPLIFIED TROUGH THROUGH THE GREAT BASIN BY EARLY TUESDAY. DERIVED IMAGERY AND RAOB DATA SHOWS A SIGNIFICANT DECREASE IN MOISTURE THE PAST 24 HOURS AS THE MONSOONAL PLUME HAS BEEN DIRECTED INTO THE EASTERN PLAINS. AT GJT AND UPSTREAM PWATS ARE BELOW NORMAL FOR THIS TIME OF YEAR. THERE ARE SOME RETURNS SHOWING UP ON RADAR WITH LOW LEVEL MOISTURE...MOUNTAIN CIRCULATIONS AND INSTABILITY BEING ENHANCED BY A JET ALOFT. THE FOCUS FOR OVERNIGHT SHOULD MAINLY BE ACROSS THE NORTH WHERE VEERING MID LEVEL PROFILES AND THE PASSING JET MAXIMA WILL ADD JUST ENOUGH ASCENT TO KEEP NOCTURNAL CONVECTION FIRING. HAVE THROWN OUT THE AGGRESSIVE GFS QPF OUTPUT ATTM WITH IT NOT VERIFYING SO FAR THIS AFTERNOON. THETA SURFACES NEAR 315K SHOW DECENT UPGLIDE NORTH OF INTERSTATE 70 TONIGHT WHILE ALSO HINT AT SOME TAP TO THE TROPICAL MOISTURE LEFT OVER FROM WHAT IS LEFT OF MARIE. THIS TAP DOES NOT LOOK TO GREATLY ENHANCE THE MOISTURE ADVECTION TONIGHT BUT MAY PLAY SOME ROLE IN STORM FORMATION OVER THE EASTERN DIVIDE MOUNTAINS FOR MONDAY. AGAIN MONDAY LOOKS TO BE SOMEWHAT OF A DOWN DAY AS THE JET ALOFT WEAKENS AND OVERALL PWATS REMAIN BELOW NORMAL. A SMALL RIBBON OF THE MOISTURE MENTIONED ABOVE LOOKS TO FAVOR CONVECTION OVER THE CENTRAL DIVIDE MOUNTAINS UNDER CONFLUENT FLOW ALOFT. THIS ALL HANDLED WELL IN THE GOING GRID FORECAST SO ONLY SMALL TWEAKS NEEDED. TEMPERATURES SHOULD BE A BIT MORE MILD OVERNIGHT UNDER WAA AND PUSH SOME 3 TO 7 DEGREES UPWARD FOR TUESDAY. TUESDAY NIGHT THE FLOW BACKS MORE SOUTHERLY ALOFT AS THE MAIN TROF AXIS BECOME ORIENTED MORE MERIDIONALLY. MONSOON AND TROPICAL MOISTURE LOOK TO BE FORCED NORTHWARD IN THIS FLOW AND THERE SHOULD BE AN INCREASE IN CONVECTION FROM MIDNIGHT TOWARD SUNRISE...SETTING UP A MORE ACTIVE DAY FOR TUESDAY. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 255 PM MDT SUN AUG 24 2014 THE CHALLENGE OF THESE PERIODS HAS BEEN THE TIMING AND THEREFORE THE PLACEMENT OF THE UPPER LOW THAT WILL DIG OVER THE REGION. THE EC AND NAM ARE IN GOOD AGREEMENT WITH A SLOWER SOLUTION. THE GFS AND CANADIAN PRODUCE A FASTER PROGRESSION BUT THE GFS IS SLOWER THAN ITS PREVIOUS RUNS. AS THE UPPER LOW IS DECOUPLED FROM THE POLAR FRONT JET...THE SLOWEST EC SOLUTION IS PREFERRED. SO INCREASED STORM COVERAGE AND COOLER TEMPS ARE EXPECTED THROUGH THURSDAY. TUESDAY...THE UPPER LOW DUG INTO EASTERN NEVADA ENHANCING A 75KT JET OVER THIS CWA. MOISTURE SURGES TO OVER AN INCH PRECIPITABLE WATER VALUES IN SE UTAH. WEDNESDAY THE UPPER LOW SLOWLY PROGRESSES INTO NE UTAH LOSING JET SUPPORT BUT GAINING CYCLONIC AND DIVERGENT FLOW ALOFT. PRECIP WATER VALUES REMAIN NEAR ONE INCH. STORM MOTION ALSO REMAINS BRISKLY TO THE NE AT 20 KTS LIMITING RAINFALL FORM ANY SINGLE STORM. BY THURSDAY THE LOW CENTER AMBLES TO THE CONTINENTAL DIVIDE WITH WRAP-AROUND DYNAMICS ACROSS THE NORTHERN CWA AND THE UPPER FLOW SWITCHING TO NW. SOME NOCTURNAL STORMS ARE EXPECTED THROUGH THESE PERIODS. BY FRIDAY THE EC PROGRESSES THE OPENING LOW ONTO THE EASTERN PLAINS WITH A RIDGE BUILDING IN FROM THE WEST. FRIDAY STORM ACTIVITY WILL LINGER ALONG THE CONTINENTAL DIVIDE...THEN A DRYING AND WARMING TREND INTO THE WEEKEND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1036 PM MDT SUN AUG 24 2014 SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS NORTHEAST UTAH AND NORTHWEST COLORADO THROUGH 15Z MONDAY MORNING. GUSTY WINDS TO 40 MPH AND SMALL HAIL WILL OCCUR NEAR THE STRONGEST STORMS. LOCAL MVFR CIGS POSSIBLE WITH MOUNTAINS BECOMING OBSCURED AT TIMES. SOUTH OF INTERSTATE 70...VFR CONDITIONS EXPECTED TO PERSIST THROUGH MIDDAY MONDAY. AFTER 18Z...SCATTERED SHOWERS AND THUNDERSTORMS WILL REDEVELOP OVER THE MOUNTAINS WITH ACTIVITY TRANSITIONING OUT OVER THE VALLEYS AFTER 00Z MONDAY EVENING. WITH ANY STORMS...GUSTY WINDS...HAIL AND LOWERED CIGS SHOULD BE EXPECTED...WITH MOUNTAIN TOPS BECOMING OBSCURED. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...JDC SHORT TERM...15 LONG TERM...JOE AVIATION...JDC
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1043 PM MDT SUN AUG 24 2014 .UPDATE... ISSUED AT 1036 PM MDT SUN AUG 24 2014 CONVECTION CONTINUES TO EXPAND IN AREAL COVERAGE ALONG AND NORTH OF UPPER LEVEL JET LIFTING NORTHEAST ACROSS THE FORECAST AREA LATE THIS EVENING. FEW STRONGER CELLS DEVELOPING WITH NUMEROUS OUTFLOW BOUNDARIES KICKING UP STRONGER SFC WINDS. LATEST HRRR RUNS INDICATE THIS WILL CONTINUE THROUGH THE REMAINDER OF THE NIGHT AND HAVE MADE SIGNIFICANT ADJUSTMENTS TO POPS GRIDS TO FIT CURRENT TRENDS AND EXPECTED CONDITIONS FOR THE REMAINDER OF THE NIGHT. OUTFLOW GUSTS TO 40 MPH POSSIBLE TONIGHT ALONG WITH SMALL HAIL NEAR THE STRONGER CELLS. OTHERWISE...MORE MUCH NEEDED RAIN FOR THE NORTHERN PORTIONS OF OUR FORECAST AREA. UPDATE ISSUED AT 550 PM MDT SUN AUG 24 2014 SHORT TERM UPDATE WILL BE REQUIRED EARLY THIS EVENING AS CONVECTION HAS INCREASED ACROSS EAST CENTRAL UTAH. THIS ACTIVITY MAY EXPAND INTO NW COLORADO...POSSIBLY AS FAR AS A LINE FROM MOAB TO ASPEN. THIS ACTIVITY IS IN RESPONSE TO EMBEDDED DISTURBANCE ALONG A SHEAR AXIS THAT CUTS ACROSS THE FORECAST AREA THIS EVENING. RAP AND HRRR MODELS INDICATE THAT SHOWERS AND STORMS LASTING WELL BEYOND SUNSET WILL OCCUR FROM VERNAL TO ROUTT COUNTY. IT APPEARS THAT THE LOWER RESOLUTION SUCH AS THE GFS40 IS SUGGESTING NOCTURNAL CONVECTION AS WELL. UPDATE WILL BE COMING AND WILL BE LEANING TOWARDS THE RAP/HRRR MODELS. && .SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT) ISSUED AT 255 PM MDT SUN AUG 24 2014 12Z H5 HAND ANALYSIS SHOWING A BLOCKING RIDGE EXTENDING FROM THE GULF STATES UP INTO THE CANADIAN MARITIME REGION. AS SUCH LOW PRESSURE WILL BE ANCHORING IN THE WESTERN STATES TO START OUT THE NEW WEEK. THE MORE IMPRESSIVE FEATURES SHOWING UP IN WATER VAPOR THIS AFTERNOON ARE THE PAIR OF LOWS ROTATING AROUND EACH OTHER OVER MONTANA AND WASHINGTON THIS AFTERNOON. THE FORMER RETREATING NORTHEASTWARD AND THE LATTER DROPPING SOUTHWARD WHERE IT WILL CARVE OUT A FAIRLY AMPLIFIED TROUGH THROUGH THE GREAT BASIN BY EARLY TUESDAY. DERIVED IMAGERY AND RAOB DATA SHOWS A SIGNIFICANT DECREASE IN MOISTURE THE PAST 24 HOURS AS THE MONSOONAL PLUME HAS BEEN DIRECTED INTO THE EASTERN PLAINS. AT GJT AND UPSTREAM PWATS ARE BELOW NORMAL FOR THIS TIME OF YEAR. THERE ARE SOME RETURNS SHOWING UP ON RADAR WITH LOW LEVEL MOISTURE...MOUNTAIN CIRCULATIONS AND INSTABILITY BEING ENHANCED BY A JET ALOFT. THE FOCUS FOR OVERNIGHT SHOULD MAINLY BE ACROSS THE NORTH WHERE VEERING MID LEVEL PROFILES AND THE PASSING JET MAXIMA WILL ADD JUST ENOUGH ASCENT TO KEEP NOCTURNAL CONVECTION FIRING. HAVE THROWN OUT THE AGGRESSIVE GFS QPF OUTPUT ATTM WITH IT NOT VERIFYING SO FAR THIS AFTERNOON. THETA SURFACES NEAR 315K SHOW DECENT UPGLIDE NORTH OF INTERSTATE 70 TONIGHT WHILE ALSO HINT AT SOME TAP TO THE TROPICAL MOISTURE LEFT OVER FROM WHAT IS LEFT OF MARIE. THIS TAP DOES NOT LOOK TO GREATLY ENHANCE THE MOISTURE ADVECTION TONIGHT BUT MAY PLAY SOME ROLE IN STORM FORMATION OVER THE EASTERN DIVIDE MOUNTAINS FOR MONDAY. AGAIN MONDAY LOOKS TO BE SOMEWHAT OF A DOWN DAY AS THE JET ALOFT WEAKENS AND OVERALL PWATS REMAIN BELOW NORMAL. A SMALL RIBBON OF THE MOISTURE MENTIONED ABOVE LOOKS TO FAVOR CONVECTION OVER THE CENTRAL DIVIDE MOUNTAINS UNDER CONFLUENT FLOW ALOFT. THIS ALL HANDLED WELL IN THE GOING GRID FORECAST SO ONLY SMALL TWEAKS NEEDED. TEMPERATURES SHOULD BE A BIT MORE MILD OVERNIGHT UNDER WAA AND PUSH SOME 3 TO 7 DEGREES UPWARD FOR TUESDAY. TUESDAY NIGHT THE FLOW BACKS MORE SOUTHERLY ALOFT AS THE MAIN TROF AXIS BECOME ORIENTED MORE MERIDIONALLY. MONSOON AND TROPICAL MOISTURE LOOK TO BE FORCED NORTHWARD IN THIS FLOW AND THERE SHOULD BE AN INCREASE IN CONVECTION FROM MIDNIGHT TOWARD SUNRISE...SETTING UP A MORE ACTIVE DAY FOR TUESDAY. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 255 PM MDT SUN AUG 24 2014 THE CHALLENGE OF THESE PERIODS HAS BEEN THE TIMING AND THEREFORE THE PLACEMENT OF THE UPPER LOW THAT WILL DIG OVER THE REGION. THE EC AND NAM ARE IN GOOD AGREEMENT WITH A SLOWER SOLUTION. THE GFS AND CANADIAN PRODUCE A FASTER PROGRESSION BUT THE GFS IS SLOWER THAN ITS PREVIOUS RUNS. AS THE UPPER LOW IS DECOUPLED FROM THE POLAR FRONT JET...THE SLOWEST EC SOLUTION IS PREFERRED. SO INCREASED STORM COVERAGE AND COOLER TEMPS ARE EXPECTED THROUGH THURSDAY. TUESDAY...THE UPPER LOW DUG INTO EASTERN NEVADA ENHANCING A 75KT JET OVER THIS CWA. MOISTURE SURGES TO OVER AN INCH PRECIPITABLE WATER VALUES IN SE UTAH. WEDNESDAY THE UPPER LOW SLOWLY PROGRESSES INTO NE UTAH LOSING JET SUPPORT BUT GAINING CYCLONIC AND DIVERGENT FLOW ALOFT. PRECIP WATER VALUES REMAIN NEAR ONE INCH. STORM MOTION ALSO REMAINS BRISKLY TO THE NE AT 20 KTS LIMITING RAINFALL FORM ANY SINGLE STORM. BY THURSDAY THE LOW CENTER AMBLES TO THE CONTINENTAL DIVIDE WITH WRAP-AROUND DYNAMICS ACROSS THE NORTHERN CWA AND THE UPPER FLOW SWITCHING TO NW. SOME NOCTURNAL STORMS ARE EXPECTED THROUGH THESE PERIODS. BY FRIDAY THE EC PROGRESSES THE OPENING LOW ONTO THE EASTERN PLAINS WITH A RIDGE BUILDING IN FROM THE WEST. FRIDAY STORM ACTIVITY WILL LINGER ALONG THE CONTINENTAL DIVIDE...THEN A DRYING AND WARMING TREND INTO THE WEEKEND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1036 PM MDT SUN AUG 24 2014 SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS NORTHEAST UTAH AND NORTHWEST COLORADO THROUGH 15Z MONDAY MORNING. GUSTY WINDS TO 40 MPH AND SMALL HAIL WILL OCCUR NEAR THE STRONGEST STORMS. LOCAL MVFR CIGS POSSIBLE WITH MOUNTAINS BECOMING OBSCURED AT TIMES. SOUTH OF INTERSTATE 70...VFR CONDITIONS EXPECTED TO PERSIST THROUGH MIDDAY MONDAY. AFTER 18Z...SCATTERED SHOWERS AND THUNDERSTORMS WILL REDEVELOP OVER THE MOUNTAINS WITH ACTIVITY TRANSITIONING OUT OVER THE VALLEYS AFTER 00Z MONDAY EVENING. WITH ANY STORMS...GUSTY WINDS...HAIL AND LOWERED CIGS SHOULD BE EXPECTED...WITH MOUNTAIN TOPS BECOMING OBSCURED. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...JDC SHORT TERM...15 LONG TERM...JOE AVIATION...JDC
AREA FORECAST DISCUSSION
NWS MIAMI FL
256 AM EDT MON AUG 25 2014 .SHORT TERM (TODAY-WEDNESDAY)... IT CONTINUES TO LOOK MORE FAVORABLE THAT T.S. CRISTOBAL WILL MOVE NORTH AND NORTHEAST AWAY FROM SOUTH FLORIDA. SO THE PRIMARY IMPACTS WILL BE AN INCREASE IN RIP CURRENTS AT THE ATLANTIC BEACHES AND BUILDING SEAS IN THE ATLANTIC FOR MARINE INTERESTS AS A SMALL NORTHEAST SWELL IS GENERATED. MODELS SUGGEST A MOISTURE SURGE MOVING INTO THE REGION AFTER 12Z THIS MORNING WHICH IS A RESULT IN THE NORTHEAST CIRCULATION DEVELOPING WITH CRISTOBAL. THE CURRENT PWAT IS AROUND 1.75 INCHES WITH FORECAST SOUNDINGS SHOWING AN INCREASE TO 2+ INCHES THIS MORNING. THE STEERING FLOW WILL BE NORTHEAST TO SOUTHWEST SO THE EAST COAST COULD GET A QUICK PASSING SHRA/TSRA WITH THE GREATEST ACTIVITY BEING OVER THE INTERIOR AND SOUTHWEST COAST. THE HRRR IS SHOWING SOMETHING VERY SIMILAR WITH SCATTERED SHOWERS NEAR THE EAST COAST WITH A FLARE UP INLAND AROUND THE LAKE AFTER 17Z. MUCH DRIER AIR ALOFT WILL THEN MOVE INTO SOUTH FLORIDA ON TUESDAY WITH FORECAST SOUNDINGS SHOWING PWAT DROPPING TO LESS THAN 1.25 INCHES WITH THE NORTHEAST STEERING FLOW CONTINUING SO ONLY ISOLATED OR LOW END SCATTERED IS EXPECTED ACROSS THE INTERIOR AND SOUTHWEST COAST TUESDAY AFTERNOON/EVENING. THEY DRYING TREND WILL PERSIST INTO WEDNESDAY ALTHOUGH FORECAST SOUNDINGS DO SHOW A SLIGHT RETURN OF MOISTURE WITH PWAT CLIMBING BACK TO OVER 1.5 INCHES BY LATE IN THE DAY. STILL, NOT MUCH COVERAGE IS ANTICIPATED WITH A MORE SOUTHEAST STEERING FLOW PATTERN RETURNING SO STORMS WOULD TEND TO FORM INLAND FROM THE EAST COAST AND BE CONCENTRATED OVER THE INTERIOR ONLY. .LONG TERM (THURSDAY-SUNDAY)... AS CRISTOBAL EXITS TO THE NORTHEAST, A DEEP LAYER RIDGE WILL BUILD BACK TO THE NORTH LATE THIS WEEK INTO THE UPCOMING WEEKEND WITH AN INCREASE IN MOISTURE AND PWATS RETURNING TO NEAR NORMAL VALUES. THIS WOULD CONTINUE TO STEER THE STORMS AWAY FROM THE EAST COAST TO THE INTERIOR AND WEST COAST REGIONS. NO OTHER TROPICAL SYSTEMS ARE EXPECTED TO AFFECT SOUTH FLORIDA THROUGH THE EXTENDED PERIOD. && .MARINE... NORTHEAST WINDS WILL PREVAIL THROUGH MIDWEEK, STRENGTHENING A TAD TODAY AND TUESDAY AS THE PRESSURE GRADIENT TIGHTENS. THIS WILL LEAD TO INCREASING SEAS ESPECIALLY IN THE GULF STREAM OFF THE PALM BEACH COAST...WHERE HAZARDOUS SEAS OF 7+ FT ARE POSSIBLE DUE TO FLOW COUNTERACTING THE GULF STREAM CURRENT ALONG WITH AN INCOMING SMALL NORTHEAST SWELL. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 91 80 91 79 / 40 20 10 10 FORT LAUDERDALE 91 81 92 81 / 40 20 10 10 MIAMI 89 80 91 79 / 60 20 10 10 NAPLES 92 78 93 77 / 60 30 20 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ SHORT TERM...30/KOB LONG TERM....30/KOB AVIATION.....23/SK
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
335 AM CDT MON AUG 25 2014 .SYNOPSIS... ISSUED AT 334 AM CDT MON AUG 25 2014 THUNDERSTORMS HAVE DEVELOPED EARLY THIS MORNING ALONG AND AHEAD OF THE SURFACE FRONT EXTENDING ROUGHLY FROM WESTERN LAKE SUPERIOR SW ACROSS WESTERN WI...SW MN...INTO W CENTRAL IA. THIS WAS ALONG AN AXIS OF HIGH THETAE INDICATED BY 850 MB DEWPOINTS OF 14 TO 16 C FROM NORTHEAST KS INTO SW ONTARIO AT 00Z...WITH CONVERGENCE ASSISTED BY 35KT TO 40 KT SW WINDS AT 850 MB. THIS MOISTURE WAS BEING PULLED NORTHWARD BY A STRONG SURFACE AND UPPER LEVEL LOW SEEN ON WV IMAGERY ALONG THE ND/MANITOBA BORDER. AT 3 AM...THE LEADING LINE OF SCATTERED THUNDERSTORMS WAS MOVING INTO BUCHANAN AND BENTON COUNTIES...INTO A VERY HUMID AIRMASS WITH DEWPOINTS IN THE LOWER TO MID 70S AND AIR TEMPERATURES IN THE MID TO UPPER 70S. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 334 AM CDT MON AUG 25 2014 FORECAST CHALLENGES CENTER ON THUNDERSTORMS THIS MORNING AND AGAIN TONIGHT...AND HEAT HEADLINES TODAY AS THE HOT AND HUMID CONDITIONS PERSIST OVER THE REGION. IN THE NEAR TERM...A SEMI-LINEAR MCS WILL LIKELY MOVE ACROSS THE FORECAST AREA MAINLY NORTH OF I-80...DRIVEN BY A WEAK SHORTWAVE FLOW IN THE NW FLOW ALOFT. WHILE NO INDIVIDUAL FORECAST MODEL HAS HAD A GOOD HANDLE ON TRENDS OVERNIGHT...THE HIGH RES WRF AND RAP MODELS APPEAR TO HAVE THE BEST HANDLE ON THE CONVECTION ENTERING THE NORTH. THESE HAVE THE THUNDERSTORMS ADVANCING THROUGH THE NORTH OVER THE NEXT SEVERAL HOURS AND THEN DISSIPATING BY NOON...AND HAVE TRENDED THE FORECAST ACCORDINGLY. THE LATEST RAP IS ALONE WITH DEVELOPING THUNDERSTORMS IN THE HIGH MUCAPE AXIS FURTHER SE...OVER 4000 J/KG...OVER W CENTRAL IL TOWARD SUNRISE...WHICH WHILE NOT IN THE CURRENT FORECAST CANNOT BE ENTIRELY RULED AND WILL WATCH TRENDS CLOSELY. OTHERWISE...THIS SHOULD BE FOLLOWED BY CLEARING SKIES AND A RETURN TO THE HEAT AND HUMIDITY SEEN OVER THE AREA YESTERDAY. DUE TO UNCERTAINTIES IN THE TIMING OF THE DISSIPATING MCS IN THE NORTH AND POSSIBLE DEBRIS CLOUDS FROM STORMS IN THE PLAINS...ALONG WITH 850 MB TEMPERATURES PROGGED ABOUT 1 DEGREE COOLER...HAVE TRENDED HIGHS A DEGREE OR TWO COOLER THAN SUNDAY...WITH UPPER 80S NW TO LOWER 90S CENTRAL AND SOUTH. DEWPOINTS WILL HOLD IN THE LOWER TO MID 70S AND POSSIBLY TOUCH THE UPPER 70S AT TIMES LATE IN THE DAY. THIS COMBINATION WILL SEND HEAT INDEX VALUES TO JUST ABOVE 100 ACROSS THE SOUTH AND WILL KEEP THE PREVIOUS HEAT ADVISORY CONFIGURATION IN PLACE. TONIGHT...THE SETUP WILL BE FAVORABLE FOR ANOTHER MCS AS THE SURFACE FRONT SLOWLY ADVANCES THROUGH THE FORECAST AREA AND MODEST CONVERGENCE OCCURS IN THE 850 MB THETAE AXIS AS IT SHIFTS OVERHEAD. HAVE KEPT LIKELY POPS IN THE NORTH WITH SLIGHT TO LOW END CHANCE POPS IN THE SOUTH TOWARD MORNING. THE MAIN THREAT WILL BE LOCALLY HEAVY RAINFALL. IT WILL BE ANOTHER WARM AND VERY HUMID NIGHT WITH TEMPERATURES AND DEWPOINTS IN THE 70S...EXCEPT IN THE FAR NW...WHERE THE CURRENT FRONTAL TIMING SUGGESTS READINGS LOWERING INTO THE UPPER 60S. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 334 AM CDT MON AUG 25 2014 AN ORGANIZED THUNDERSTORM COMPLEX SHOULD MOVE INTO THE AREA TUESDAY MORNING AND DISSIPATE DURING THE MORNING. BOUNDARIES LEFT OVER FROM THIS COMPLEX COMBINED WITH A WEAK FRONT MOVING THROUGH THE AREA WILL PROVIDE THE FOCUS FOR NEW CONVECTION TUESDAY AFTERNOON AND EVENING. HIGH MOISTURE LEVELS IN THE LOWER ATMOSPHERE MEANS ANY STORM WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL. CLOUD COVER AND RAIN WILL PLAY INTO HOW WARM IT WILL GET ON TUESDAY. THE SOUTHEAST HALF MAY SEE TEMPERATURES AROUND 90 WITH HEAT INDEX READINGS IN THE UPPER 90S TO JUST OVER 100. ANOTHER THUNDERSTORM COMPLEX IS EXPECTED TO DEVELOP IN WESTERN IOWA TUESDAY EVENING AND THEN MOVE MAINLY EAST OVERNIGHT INTO WEDNESDAY MORNING. THIS STORM COMPLEX SHOULD ARRIVE IN THE WESTERN THIRD OF THE CWFA IN THE PRE-DAWN HOURS AND SLOWLY DISSIPATE ACROSS THE AREA WEDNESDAY MORNING. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE FROM THE STORMS DUE TO HIGH MOISTURE LEVELS. LIKE TUESDAY...BOUNDARIES LEFT OVER FROM THE WEDNESDAY STORM COMPLEX WILL PROVIDE THE FOCUS FOR NEW CONVECTION WEDNESDAY AFTERNOON AND EVENING. SIGNALS FROM THE MODELS SUGGEST YET ANOTHER THUNDERSTORM COMPLEX WILL DEVELOP IN WESTERN IOWA WEDNESDAY EVENING AND MOVE GENERALLY EAST OVERNIGHT AND ARRIVE IN THE WESTERN THIRD OF THE AREA IN THE PRE-DAWN HOURS. LOCALLY HEAVY RAINFALL MAY BE POSSIBLE FROM SOME OF THE STRONGER STORMS. THURSDAY ON... THE MODEL CONSENSUS HAS CHANCE POPS IN EACH 12 HOUR PERIOD FROM THURSDAY THROUGH SATURDAY NIGHT. TEMPERATURES SHOULD BE NEAR NORMAL. ON SUNDAY...THE MODEL CONSENSUS HAS SLIGHT CHANCE TO LOW CHANCE POPS. THE LARGE SCALE PICTURE SUGGESTS THE WEATHER PATTERN WILL REMAIN FAIRLY ACTIVE WITH A FRONT STALLED OUT JUST SOUTH OF THE AREA. IT WILL NOT RAIN CONTINUOUSLY THE ENTIRE TIME. THERE WILL BE PERIODS OF DRY WEATHER THAT MAY LAST 6 OR 12 HOURS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1125 PM CDT SUN AUG 24 2014 AN APPROACHING FRONT BRINGS THE THREAT FOR SHOWERS AND THUNDERSTORMS TO EASTERN IOWA AFTER 08Z LATE TONIGHT. IT IS NOT CERTAIN THAT THEY WILL IMPACT THE AREA...AND A VCSH IS CONTINUED TO BE USED TO DESCRIBE THIS LATE NIGHT THREAT WITH TEMPORARY 5SM TSRA POSSIBLE AT BOTH CID AND DBQ. IF THE LINE OF STORMS VERIFY OVERNIGHT IN EASTERN IOWA...MVFR CONDITIONS ARE LIKELY TO OCCUR ESPECIALLY AT CID AND DBQ AND POSSIBLY AT MLI. OTHERWISE...LATE NIGHT AND EARLY MORNING MVFR FOG IS LIKELY AT ALL SITES DUE TO THE VERY MOIST AIR MASS IN PLACE IN THE REGION. AFTER 15Z MONDAY...A RETURN TO HOT VFR WEATHER IS EXPECTED. SOUTH TO SOUTHEAST WINDS OF 5 TO 9 KTS ARE EXPECTED THROUGH THE PERIOD. ANOTHER THREAT FOR A SHOWER OR STORM WILL ARRIVE BY LATE AFTERNOON MONDAY AND CONTINUE INTO MONDAY NIGHT. ERVIN && .DVN WATCHES/WARNINGS/ADVISORIES... IA...HEAT ADVISORY FROM NOON TODAY TO 8 PM CDT THIS EVENING FOR LOUISA-MUSCATINE-SCOTT. HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR DES MOINES-HENRY IA-LEE-VAN BUREN. IL...HEAT ADVISORY FROM NOON TODAY TO 8 PM CDT THIS EVENING FOR BUREAU-HENRY IL-MERCER-PUTNAM-ROCK ISLAND-WHITESIDE. HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR HANCOCK-HENDERSON- MCDONOUGH-WARREN. MO...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR CLARK-SCOTLAND. && $$ SYNOPSIS...SHEETS SHORT TERM...SHEETS LONG TERM...08 AVIATION...ERVIN
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
224 AM CDT Mon Aug 25 2014 ...Updated long term section... .SHORT TERM...(Today and tonight) ISSUED AT 155 AM CDT MON AUG 25 2014 A wedge of warm 850mb to 700mb temperatures that was located just south of a surface boundary which extended from the Oklahoma panhandle to northeast Kansas at 00z Monday will lift north today and by 00z Tuesday this warm air will be located across most of western and south central Kansas. Based on the the forecast mixing height and the 00z Tuesday temperatures in the 850mb to 700mb level from the NAM and GFS it will be another day with highs in the upper 90s to near 100 degrees across most of western and south central Kansas. In addition to the warming temperatures 700mb moisture will also be improving across central and north central Kansas which may give rise to some afternoon convection as CAPE values increase to 1000 to 2000 j/kg, especially across northern Kansas. At this time it appears the better forcing and instability late today along with the better low level moisture will be near/north the surface boundary in north central Kansas so will focus late day convection around and north of the interstate 70 corridor with more widely scattered storms being possible further south. Tonight warm air advection and moisture advection improves near the nose of a developing low level jet. This will be just north of a surface boundary that will remain nearly stationary early tonight across west central and north central Kansas. At the same time an upper level trough is forecast to cross northwest Kansas. As a result will increase the chances for convection across west central and north central Kansas, especially north of where the +12c to +14c 700mb temperature gradient is forecast to be located by the NAM and GFS at 06z and 12z Tuesday. Preciptable water values Monday night are forecast to range from 1.5 to 1.75 across northern Kansas so some storms tonight may produce periods of heavy rainfall. Also am unable to rule out the chance for some storms becoming severe Monday evening north of the interstate 70 corridor base on 0-6km shear of 30 to 40 knots and CAPE values ranging from 1500 to near 3000 j/kg at 00z Tuesday from the NAM and GFS. Main hazard at this time appears to be quarter size hail and wind gusts of 60 mph or greater. .LONG TERM...(Tuesday through Sunday) ISSUED AT 223 AM CDT MON AUG 25 2014 An upper level low will trek from the Pacific northwest Monday to the Central Plains by Friday before exiting the area this weekend. Mid to upper levels of the atmosphere will saturate as this system approaches bringing increasing cloudiness to western Kansas. Towards the surface, a frontal boundary is expected to be positioned across west central Kansas Tuesday before lifting northward to northern Kansas and Nebraska Wednesday into Thursday. This frontal boundary will be the main focal point where thunderstorms are expected to develop. There could also be storms developing along the higher terrain across eastern Colorado before moving into western Kansas later on. A cold front is then progged to move through the area Thursday with wrap around moisture in place Friday. Thunderstorm chances envelop the CWA Wednesday night through Friday before tapering off Friday night. A drier pattern then sits up for this weekend with partly cloudy skies expected. As for temperatures, highs will start out in the 90s Tuesday and Wednesday before cooling off into the 80s Thursday through Saturday. Highs Sunday look to top out in the lower 90s. Lows are forecasted to range from the mid 60s across west central Kansas to lower 70s across south central Kansas Tuesday through Thursday morning before cooling off into the 60s Friday into this weekend. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) ISSUED AT 1205 AM CDT MON AUG 25 2014 A weak surface boundary will lift north across western Kansas overnight. As this boundary moves into west central and north central Kansas the surface winds will become south southeast at around 10 knots by 12z Monday. Based on 03z verification from the NAM and HRRR will stay close to these models on timing of the wind shift overnight. Southerly winds will increase to around 15 knots by the early afternoon. BUFR soundings indicating VRF conditions will prevail overnight and Monday as moisture around the 700mb level improves during the Day on Monday. Late day instability and forcing across north central Kansas may also give rise to some scattered evening convection but given the scatters nature of the storms late Monday will not include mention of thunderstorms yet in the Hays 06z tafs. && .PRELIMINARY POINT TEMPS/POPS... DDC 98 69 96 69 / 20 20 30 30 GCK 98 67 94 67 / 20 30 40 40 EHA 96 67 93 67 / 20 20 40 30 LBL 98 69 96 69 / 20 20 30 30 HYS 98 68 94 68 / 30 70 50 50 P28 100 73 99 74 / 10 20 20 20 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Burgert LONG TERM...Hovorka_42 AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
159 AM CDT Mon Aug 25 2014 ...Updated short term discussion... .SHORT TERM...(Today and tonight) ISSUED AT 155 AM CDT MON AUG 25 2014 A wedge of warm 850mb to 700mb temperatures that was located just south of a surface boundary which extended from the Oklahoma panhandle to northeast Kansas at 00z Monday will lift north today and by 00z Tuesday this warm air will be located across most of western and south central Kansas. Based on the the forecast mixing height and the 00z Tuesday temperatures in the 850mb to 700mb level from the NAM and GFS it will be another day with highs in the upper 90s to near 100 degrees across most of western and south central Kansas. In addition to the warming temperatures 700mb moisture will also be improving across central and north central Kansas which may give rise to some afternoon convection as CAPE values increase to 1000 to 2000 j/kg, especially across northern Kansas. At this time it appears the better forcing and instability late today along with the better low level moisture will be near/north the surface boundary in north central Kansas so will focus late day convection around and north of the interstate 70 corridor with more widely scattered storms being possible further south. Tonight warm air advection and moisture advection improves near the nose of a developing low level jet. This will be just north of a surface boundary that will remain nearly stationary early tonight across west central and north central Kansas. At the same time an upper level trough is forecast to cross northwest Kansas. As a result will increase the chances for convection across west central and north central Kansas, especially north of where the +12c to +14c 700mb temperature gradient is forecast to be located by the NAM and GFS at 06z and 12z Tuesday. Preciptable water values Monday night are forecast to range from 1.5 to 1.75 across northern Kansas so some storms tonight may produce periods of heavy rainfall. Also am unable to rule out the chance for some storms becoming severe Monday evening north of the interstate 70 corridor base on 0-6km shear of 30 to 40 knots and CAPE values ranging from 1500 to near 3000 j/kg at 00z Tuesday from the NAM and GFS. Main hazard at this time appears to be quarter size hail and wind gusts of 60 mph or greater. .LONG TERM...(Monday night through Sunday) ISSUED AT 305 PM CDT SUN AUG 24 2014 An upper level trough will move from Nevada and into the Intermountain West on Wednesday, then into the Central Plains on Thursday, and will be slow to exit the Central Plains by Saturday afternoon. New model runs have this upper system slowing down its progress and this will allow for thunderstorm chances Tuesday into Saturday, with the best chances from Tuesday night into Thursday with a cold front. The storms may linger near to east of Dodge City on Saturday as the upper wave moves eastward. Severe storm chances do not look all that favorable with fairly weak upper level wind fields. Daytime highs will be warm and in the mid to upper 90s ahead of the front on Tuesday, then in the low to mid 90s on Wednesday, cooling into the 80s for Thursday and Friday. Highs warm back up to around 90 for the Weekend. Overnight lows around 70 on Monday night and Tuesday night cool into the 60s into the Weekend. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) ISSUED AT 1205 AM CDT MON AUG 25 2014 A weak surface boundary will lift north across western Kansas overnight. As this boundary moves into west central and north central Kansas the surface winds will become south southeast at around 10 knots by 12z Monday. Based on 03z verification from the NAM and HRRR will stay close to these models on timing of the wind shift overnight. Southerly winds will increase to around 15 knots by the early afternoon. BUFR soundings indicating VRF conditions will prevail overnight and Monday as moisture around the 700mb level improves during the Day on Monday. Late day instability and forcing across north central Kansas may also give rise to some scattered evening convection but given the scatters nature of the storms late Monday will not include mention of thunderstorms yet in the Hays 06z tafs. && .PRELIMINARY POINT TEMPS/POPS... DDC 98 69 96 69 / 20 20 30 30 GCK 98 67 94 67 / 20 30 30 40 EHA 96 67 93 66 / 10 20 40 30 LBL 98 69 95 68 / 10 20 30 30 HYS 98 68 94 69 / 20 70 40 40 P28 100 73 98 74 / 10 20 20 20 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Burgert LONG TERM...Kruse AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1208 AM CDT Mon Aug 25 2014 ...Updated synopsis and aviation discussion... .SYNOPSIS... ISSUED AT 1205 AM CDT MON AUG 25 2014 At 00z Monday a 500mb ridge axis extended from eastern Texas to the western Great Lakes region. A 700mb to 500mb low was located over western North Dakota with a +70 knot 300mb jet extending from the base of this upper low near northeast Colorado to Minnesota. Further west southwest another upper level trough was over eastern Oregon/southwest Idaho and a +90 knot 300mb jet was located on the west side of this system. Over the Central Plains the 700mb temperatures at 00z Monday ranged from +9c at North Platte to +13c at Amarillo. 850mb temperatures ranged from 21C at North Platte to +28c at Amarillo. A weak surface frontal boundary extended from the western Oklahoma panhandle to northeast Kansas. An area of mid 60s to around 70 degree surface dew points were located just north of this surface boundary which stretched from north central Kansas to southeast Nebraska. 850mb and 700mb moisture axis was located from eastern Oklahoma to southeast Nebraska. && .SHORT TERM...(This evening through Monday) ISSUED AT 320 PM CDT SUN AUG 24 2014 A strong shortwave trough was ejecting northeastward into the northern plains this afternoon. The associated cold front had pushed into southwest Kansas and stalled out. A few thunderstorms can`t be ruled out in south central Kansas this evening ahead of the cold front. Some elevated shower activity may develop tonight along the Interstate 70 corridor to the south of the upper level jet streak; but most of the precipitation should stay farther north. The front will slowly edge northward tonight and Monday as the next upper level trough digs into Nevada. This will result in a resumption of southerly winds at 5 to 10 kts late tonight across much of southwest Kansas. Lows will be mainly in the 60s to lower 70s. By Monday afternoon, thunderstorms will develop along the stalled out front in northern Kansas where low level moisture will be converging. Thunderstorms may also develop farther south into western Kansas ahead of a weak dryline. The best chance of severe storms with large hail will be well north of Interstate 70 where surface based CAPE and vertical wind shear will be stronger. High temperatures ought to be in the upper 90s to near 100F given mostly sunny skies with south winds. .LONG TERM...(Monday night through Sunday) ISSUED AT 305 PM CDT SUN AUG 24 2014 An upper level trough will move from Nevada and into the Intermountain West on Wednesday, then into the Central Plains on Thursday, and will be slow to exit the Central Plains by Saturday afternoon. New model runs have this upper system slowing down its progress and this will allow for thunderstorm chances Tuesday into Saturday, with the best chances from Tuesday night into Thursday with a cold front. The storms may linger near to east of Dodge City on Saturday as the upper wave moves eastward. Severe storm chances do not look all that favorable with fairly weak upper level wind fields. Daytime highs will be warm and in the mid to upper 90s ahead of the front on Tuesday, then in the low to mid 90s on Wednesday, cooling into the 80s for Thursday and Friday. Highs warm back up to around 90 for the Weekend. Overnight lows around 70 on Monday night and Tuesday night cool into the 60s into the Weekend. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) ISSUED AT 1205 AM CDT MON AUG 25 2014 A weak surface boundary will lift north across western Kansas overnight. As this boundary moves into west central and north central Kansas the surface winds will become south southeast at around 10 knots by 12z Monday. Based on 03z verification from the NAM and HRRR will stay close to these models on timing of the wind shift overnight. Southerly winds will increase to around 15 knots by the early afternoon. BUFR soundings indicating VRF conditions will prevail overnight and Monday as moisture around the 700mb level improves during the Day on Monday. Late day instability and forcing across north central Kansas may also give rise to some scattered evening convection but given the scatters nature of the storms late Monday will not include mention of thunderstorms yet in the Hays 06z tafs. && .PRELIMINARY POINT TEMPS/POPS... DDC 69 96 69 92 / 20 30 30 30 GCK 67 94 67 88 / 30 30 40 30 EHA 67 93 66 87 / 20 40 30 30 LBL 69 95 68 89 / 20 30 30 30 HYS 68 94 69 90 / 30 40 40 30 P28 73 98 74 95 / 10 20 20 20 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Burgert SHORT TERM...Finch LONG TERM...Kruse AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
536 AM EDT MON AUG 25 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 535 AM EDT MON AUG 25 2014 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A VIGOROUS LOOKING SHORTWAVE LIFTING THRU ND INTO MANITOBA. ASSOCIATED SFC LOW WAS MOVING INTO SE MANITOBA WITH COLD FRONT EXTENDING THRU FAR ERN MN. AS EXPECTED...SCT TSTMS DEVELOPED AHEAD OF FRONT IN MN LATE YESTERDAY AFTN/EVENING. STORMS THEN ORGANIZED INTO A LINE AND PUSHED E INTO WI/UPPER MI. AS OF 09Z...SHRA/TSTMS EXTENDED FROM NCNTRL LAKE SUPERIOR TO THE HURON MTNS AND CRYSTAL FALLS. CONVECTION HAS HELD TOGETHER FOR MUCH OF THE NIGHT...AND IT HAS ONLY BEEN IN THE LAST HR OR TWO THAT A NOTABLE DIMINISHING TREND HAS BEGUN. NSSL WRF RUN FROM 00Z/24 AUG DID A GREAT JOB AND BETTER THAN ANY OTHER MODEL IN CAPTURING WHAT OCCURRED LAST NIGHT INTO EARLY THIS MORNING... INCLUDING THE DIMINISHING TREND NOW UNDERWAY. WHILE THERE IS STILL SOME INCREASE IN INSTABILITY AHEAD OF CONVECTION PER SPC MESOANALYSIS OF 3HR ML/MUCAPE CHANGE...OVERALL MAGNITUDE OF INSTABILITY IS NOTABLY LESS THAN WHAT WAS SUPPORTING THE CONVECTION EARLIER IN THE NIGHT. DIMINISHING INSTABILITY COMBINED WITH WEAKENING LOW-LEVEL JET WILL CONTINUE TO CAUSE SHRA/TSRA TO WEAKEN AS THEY PUSH E THIS MORNING. QUESTION THEN BECOMES WHETHER THERE WILL BE REDEVELOPMENT ALONG THE MOISTURE AXIS THAT WILL BE SLOWING DOWN. NSSL WRF INCLUDING THE NCEP ARW/NMM WHICH ALSO DID WELL WITH CONVECTION LAST NIGHT SUGGEST LITTLE OR NO ADDITIONAL DEVELOPMENT THIS AFTN. WILL BASICALLY FOLLOW THAT SCENARIO GIVEN A LACK OF MUCH FORCING THIS AFTN. WITH INCREASING SUNSHINE AND 850MB THERMAL RIDGE OVER THE AREA...TODAY SHOULD BE THE WARMEST DAY OF THE WEEK. FCST SOUNDINGS SUPPORT MAX TEMPS AS HIGH AS THE MID/UPPER 80S OVER ROUGHLY THE W HALF. COULD BE WARMER DEPENDING ON HOW QUICKLY CLOUDS SCATTER OUT. E WILL BE COOLER WITH MORE CLOUD COVER AND CONTINUED SOUTHERLY FLOW OFF LAKE MICHIGAN. LOOKS LIKE A SECONDARY COLD FRONT/TROF WILL SWEEP ACROSS THE AREA LATER THIS AFTN/EVENING. AS THE TROF MOVES INTO THE ERN FCST AREA THIS EVENING WHERE MOISTURE/INSTABILITY LINGER...ISOLD SHRA AND PERHAPS A TSRA MAY DEVELOP FROM ERN LAKE SUPERIOR INTO ERN UPPER MI. OTHERWISE...EXPECT A DRY NIGHT...BECOMING COOLER AND LESS HUMID. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 403 AM EDT MON AUG 25 2014 A FAIRLY QUIET AND GENERALLY DRY LONG TERM PERIOD IS IN STORE FOR THE UPPER GREAT LAKES REGION FOR TUESDAY THROUGH THE WEEKEND. THIS TRANSITION WILL OCCUR AS A RESULT OF THE LOW PRESSURE SYSTEM MOVING THROUGH NORTHERN ONTARIO TODAY AND THE ASSOCIATED COLD FRONT THAT PASSES THROUGH. BEHIND THIS LOW AND ASSOCIATED SHORTWAVE...HIGH PRESSURE FROM THE EASTERN DAKOTAS WILL SHIFT EAST OVER THE UPPER GREAT LAKES REGION BY WEDNESDAY WHILE A WEAK UPPER TROUGH SWEEPS THROUGH. IN GENERAL...EXPECT THIS HIGH PRESSURE RIDGE TO SUPPRESS ANY PRECIPITATION TO THE SOUTH OF THE AREA THROUGH THURSDAY. THERE ARE A COUPLE MINOR ITEMS TO NOTE. FIRST...THE SECONDARY SHORTWAVE MOVING THROUGH THE FLOW LATE TUESDAY NIGHT INTO WEDNESDAY MORNING COULD TRY TO SPARK AN ISOLATED SHOWER BUT FEEL THE DRY AIR IN THE LOWER LEVELS ASSOCIATED WITH THE HIGH PRESSURE RIDGE WILL INHIBIT ANY RAIN FROM REACHING THE SURFACE. THUS...WILL JUST SHOW PASSING MID CLOUDS AS THAT WAVE MOVES THROUGH. THE OTHER ITEM IS THE MUCH COOLER AIR BELOW 850MB THAT WILL BE SURGING INTO THE CWA LATE TONIGHT INTO TUESDAY. THIS WILL SETUP A RETURN TO ANOTHER COOLER PERIOD OF HIGH TEMPERATURES OVER THE CWA. WITH THE COLD AIR JUST STARTING TO MOVE IN ON TUESDAY...HIGHS OVER THE CENTRAL/EAST WILL STILL RISE INTO THE UPPER 60S AND LOWER 70S WHILE AREAS OVER THE WEST NEAR LAKE SUPERIOR WILL STAY IN THE MID 60S WITH THE GUSTY WESTERLY WIND OFF THE LAKE. WEDNESDAY WILL BE THE COOLEST DAY (AIDED BY THE MORNING MID CLOUDS LIMITING HEATING AND MODEL AVERAGE 850MB TEMPS AROUND 6-7C)...WITH HIGHS IN THE 60S OVER MOST OF THE CWA. 850MB TEMPS WILL REBOUND SLIGHTLY ON THURSDAY AND ALLOW HIGHS TO BE IN THE UPPER 60S TO AROUND 70 DEGREES. ALONG WITH THAT COOLER AIR ON TUESDAY MORNING...SOME OF THE MODELS ARE INDICATING ENOUGH MOISTURE FOR SOME CLOUDS OVER THE NORTH HALF OF THE CWA. THINK THE COVERAGE WILL BE THE GREATEST DURING THE AFTERNOON HOURS WHEN THE DIURNAL HEATING IS MAXIMIZED AND WILL SHOW PARTLY CLOUDY SKIES DURING THAT TIME. EXPECT MOSTLY CLEAR SKIES FOR THE REST OF THE MIDDLE OF THE WORK WEEK. THE FOCUS THURSDAY NIGHT INTO THE WEEKEND WILL BE THE UPPER DISTURBANCE MOVING OUT OF THE CENTRAL ROCKIES AND INTO THE CENTRAL PLAINS ON WEDNESDAY. THE INITIAL PORTION OF THIS WAVE WILL SHIFT NORTHEAST TOWARDS THE UPPER GREAT LAKES REGION THURSDAY NIGHT AND FRIDAY...WITH MODELS STILL VARYING ON THE NORTHWARD EXTENT OF THE WAVE AND ASSOCIATED PRECIP. CURRENT CONSENSUS IS FOR IT TO BRUSH THE SOUTHEAST THIRD OF THE CWA AND WILL SHOW SLIGHT CHANCES IN THAT AREA. THE SECOND WAVE WILL PUSH THROUGH THE AREA FRIDAY NIGHT INTO SATURDAY AND BRING ANOTHER OPPORTUNITY FOR PRECIPITATION. MODELS ALSO VARYING ON THE LOCATION THIS WAVE...SO WILL FOLLOW A BLEND OF GEM/GFS/ECMWF FOR POPS (SLIGHT OR LOW END CHANCES) WITH THE BEST CHANCES OVER THE SOUTHEAST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 140 AM EDT MON AUG 25 2014 AN APPROACHING COLD FRONT OVERNIGHT WILL BRING SCT/NMRS SHRA/TSRA INTO UPPER MI. THE BEST CHANCE FOR TSRA WILL BE ACROSS THE WEST AT IWD/CMX WHILE FARTHER EAST AT SAW...LESS FAVORABLE INSTABILITY WILL LIMIT TS CHANCES. PLENTY OF MOISTURE WILL REMAIN WITH UPSLOPE CONDITIONS BRINGING ANOTHER ROUND OF MAINLY MVFR CEILINGS TO SAW LATE IN THE NIGHT THAT SHOULD DROP TO IFR TOWARD SUNRISE. OTHERWISE... LOOK FOR SLOWLY IMPROVING CONDITIONS W TO E TODAY AS DRIER AIR WORKS IN FROM THE W BEHIND THE EXITING COLD FRONT. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 535 AM EDT MON AUG 25 2014 FOG MAY BE AN ISSUE OVER PORTIONS OF LAKE SUPERIOR THRU THIS EVENING...MAINLY CNTRL/E AND ESPECIALLY NE GIVEN THE HUMID AIR MASS AND PCPN THAT HAS OCCURRED. PASSAGE OF COLD FRONT AND ARRIVAL OF DRIER AIR TODAY/THIS EVENING WILL THEN WORK TO CLEAR OUT THE FOG FROM W TO E. BEHIND FRONT...WESTERLY WINDS WILL INCREASE TO 15-25KT OVER WRN LAKE SUPERIOR THIS AFTN AND THEN OVER CNTRL LAKE SUPERIOR THIS EVENING. THESE STRONGER WINDS WILL LINGER INTO TUE MORNING...THEN WINDS WILL DIMINISH AS HIGH PRES MOVES CLOSER TO THE AREA. THE HIGH WILL SETTLE INTO THE UPPER LAKES TUE NIGHT THRU THU...BRINGING A PERIOD OF LIGHTER WINDS MOSTLY UNDER 15KT. THE LIGHTER WINDS WILL LINGER INTO FRI DESPITE THE HIGH MOVING TO THE E. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...SRF AVIATION...JLB MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
325 AM EDT MON AUG 25 2014 LATEST UPDATE... SYNOPSIS/SHORT TERM/LONG TERM/MARINE .SYNOPSIS... ISSUED AT 325 AM EDT MON AUG 25 2014 WARM AND HUMID CONDITIONS WILL CONTINUE TODAY THROUGH TUESDAY WITH SCATTERED SHOWERS AND THUNDERSTORMS. THUNDERSTORMS THIS AFTERNOON THROUGH TUESDAY MAY CONTAIN LOCALLY HEAVY RAINFALL. DRY AND COOLER WEATHER WILL BRIEFLY RETURN WEDNESDAY FOLLOWED BY WARMER AND MORE HUMID WEATHER WITH ANOTHER CHANCE OF SHOWERS AND STORMS LATE IN THE WEEK. && .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 325 AM EDT MON AUG 25 2014 IT WILL BE VERY WARM AND HUMID TODAY WITH MAX TEMPS REACHING WELL INTO THE 80S AND DEW POINT VALUES UP INTO THE UPPER 60S TO LOWER 70S. SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP LATER TODAY AS INSTABILITY BUILDS AND SB CAPE VALUES POTENTIALLY REACH AROUND 2000-2500 J/KG NEAR TO EAST OF US-131 THIS AFTERNOON. SEVERE WX IS UNLIKELY MAINLY DUE TO WEAK DEEP LAYER SHEAR BUT AN ISOLATED SEVERE STORM CANNOT BE RULED OUT THIS AFTERNOON AND EARLY EVENING WHEN INSTABILITY WILL BE MAXIMIZED. ANY STORMS THAT DO DEVELOP COULD PRODUCE LOCALLY RAINFALL WITH PRECIPITABLE WATER VALUES UP IN THE 1.75 TO 2 INCH RANGE TODAY. SCATTERED SHOWERS AND PERHAPS A FEW STORMS WILL CONTINUE INTO THIS EVENING. THEN THE COLD FRONT WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS ON TUESDAY. THE BEST CHANCE FOR A FEW STRONG TO POTENTIALLY SEVERE STORMS TUESDAY WOULD BE IN THE AFTERNOON OVER OUR SE FCST AREA WHEN SB CAPE VALUES WILL POTENTIALLY REACH AROUND 3000 J/KG. IT HAS BEEN NOTED THAT OVERALL SHORT TO MEDIUM RANGE GUIDANCE TRENDS ARE BRINGING THE COLD FRONT THROUGH FASTER. THEREFORE WE HAVE TRIMMED BACK POPS SIGNIFICANTLY FOR TUESDAY NIGHT AND ARE KEEPING LINGERING LOW POPS CONFINED TO OUR SOUTHERN FORECAST AREA. DRY WEATHER IS NOW ANTICIPATED WEDNESDAY WITH THE HIGH PRESSURE RIDGE IN PLACE OVER THE NORTHERN GREAT LAKES REGION. .LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY) ISSUED AT 325 AM EDT MON AUG 25 2014 THE LAST COUPLE NIGHTS HAVE SEEN THE GFS GUIDANCE TREND TOWARDS THE ECMWF IN TERMS OF THE EVOLUTION OF THE PATTERN. TONIGHT...HAVE THEREFORE FOLLOWED THE LEAD OF THE ECMWF THROUGH THE LONG TERM FORECAST. THE LONG TERM LOOKS TO FEATURE A DECENT ABOUT OF RAINFALL WITH A BOUNDARY OSCILLATING THROUGH THE REGION AND NEAR NORMAL TEMPERATURES. AS FOR THE DETAILS...THE PERIOD LOOKS TO START OFF DRY WITH SURFACE HIGH PRESSURE SAGGING INTO THE AREA FROM THE NORTH WEDNESDAY NIGHT. FEEL THURSDAY WILL LIKELY BE DRY AS WELL...BUT BLENDED IN WITH NEIGHBORING OFFICES AND HAVE A 20 PCT CHANCE FOR SHOWERS/STORMS IN THE FAR WEST. CHANCES FOR SHOWERS AND STORMS THEN LOOK TO BE POSSIBLE IN THE REMAINDER OF THE FORECAST PERIOD...THURSDAY NIGHT THROUGH SUNDAY. MOISTURE COMES SURGING BACK IN THURSDAY NIGHT ESPECIALLY ALOFT. THE ECMWF HAS A WARM FRONT OR A STATIONARY BOUNDARY NEARBY FRI-SUN. HAVE CHANCE POPS ESSENTIALLY BLANKETED THROUGHOUT THIS PERIOD OF THE FORECAST. THE DAYS 4-5 AND 6-7 QPF PROGS FROM WPC ALSO BEAR THIS OUT. THEY SHOW RAINFALL TOTALS AROUND AN INCH FOR MOST AREAS...WHICH SEEMS REASONABLE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1120 PM EDT SUN AUG 24 2014 IT WOULD SEEM FOG IS BECOMING LESS LIKELY OVERNIGHT. AS I WROTE FOR THE 00Z TAF SET...THE WINDS IN THE BOUNDARY LAYER OF BETWEEN 15 AND 25 KNOTS ARE ENOUGH TO KEEP SURFACE FOG FROM BECOMING MUCH OF AN ISSUE TONIGHT. INSTEAD THE IR-FOG LOOP SHOWS PATCHY LOW CLOUDS (MVFR CIGS) DEVELOPING NEAR AND SOUTH OF I-96. AS THE AIR CONTINUES TO COOL OVERNIGHT THE LOW CLOUDS SHOULD BECOME MORE EXTENSIVE AND CIGS SHOULD LOWER SOME. SO I HAVE ONLY MVFR CIGS/VSBY AT ALL TAF SITES. THE CONVECTION FOR MONDAY STILL SEEMS POSSIBLE. THE LATEST VERSION OF THE RAP MODEL AND THE NAM12 SHOW LATE MORNING AND AFTERNOON CONVECTION. SO...I NOW HAVE VCTS AFTER 15Z FOR THAT. I WOULD EXPECT ONCE THE SUN SETS MONDAY EVENING THE CONVECTION WILL BE DONE. THERE SHOULD BE ENOUGH WIND TOMORROW NIGHT TO KEEP FOG FROM BECOMING AN ISSUE. && .MARINE... ISSUED AT 325 AM EDT MON AUG 25 2014 MINIMAL WIND AND WAVE ACTION IS ANTICIPATED TODAY THROUGH TONIGHT INTO TUESDAY. HOWEVER PATCHY FOG WILL POSE A HAZARD TO MARINERS. && .HYDROLOGY... ISSUED AT 1104 AM EDT SUN AUG 24 2014 BEST CHANCE FOR SIGNIFICANT RAINFALL WOULD BE MONDAY NIGHT THROUGH WEDNESDAY WITH A SLOW MOVING COLD FRONT. THIS IS NOT A GUARANTEE AS THE LLJ IS FORECAST TO BE QUITE WEAK. NEVERTHELESS...A VERY MOIST ATMOSPHERE COMBINED WITH FORCING VIA THE COLD FRONT AND SLOW CELL MOVEMENT COULD RESULT IN SOME SIGNIFICANT RAINFALL IF STORMS DEVELOP OVER OUR AREA. PW VALUES WILL LIKELY BE AROUND 1.75" MONDAY NIGHT AND TUESDAY. MODEL GUIDANCE IS MIXED REGARDING HOW LONG THE FRONT MAY HANG UP...SO IT IS UNCLEAR WHEN THE THREAT FOR SIGNIFICANT RAINFALL WOULD END. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS...LAURENS SHORT TERM...LAURENS LONG TERM...DUKE AVIATION...WDM HYDROLOGY...HOVING MARINE...LAURENS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
150 AM EDT MON AUG 25 2014 .SYNOPSIS... HIGH PRESSURE WILL EXPAND SOUTH ACROSS THE AREA OVERNIGHT AND WEDNESDAY...BRINGING COOL AND DRY WEATHER. TROPICAL STORM CRISTOBAL MAY BECOME A HURRICANE IN THE NEXT FEW DAYS AS IT PASSES SEVERAL HUNDRED MILES EAST OF THE CAROLINAS. A WARMING TREND WILL DEVELOP LATE IN THE WEEK. A BACKDOOR FRONT MAY APPROACH BY NEXT WEEKEND...BRINGING A RISK FOR SHOWERS AND THUNDERSTORMS. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1:50 AM MONDAY...MOST PLACES WILL REMAIN CLEAR OVERNIGHT...WITH SOME PATCHES OF STRATO-CU ALONG THE COAST. TEMPERATURES NOW DOWN INTO THE 60S MOST LOCATIONS. NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSIONS FOLLOW: ASIDE FROM A FEW PATCHES OF STRATOCUMULUS NEAR THE BEACHES SKIES ARE CLEAR AND SHOULD REMAIN MOSTLY CLEAR OVERNIGHT. THE 00Z MHX SOUNDING SHOWED A CLEAR SUBSIDENCE INVERSION AT 5300 FEET AGL AND MATCHED 18Z MODEL PROJECTIONS CLOSELY. THE ONLY CHANGE WITH THIS UPDATE WAS TO LOWER DEWPOINT FORECASTS BY A FEW DEGREES THROUGH THE NIGHT BASED ON CURRENT OBS AND THE 00Z MHX SOUNDING. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... AN EXTENSIVE STRATOCUMULUS DECK INLAND IS BEGINNING TO DECAY NOW THAT THE SUN IS SETTING. SKIES SHOULD BECOME GENERALLY CLEAR OVERNIGHT AS DRIER AIR ARRIVES IN THE 850 MB LAYER NEAR THE TOP OF TODAY`S SURFACE MIXED LAYER. BESIDES DOWNWARD ADJUSTMENTS TO SKY COVER...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE FORECAST. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS... COOL BUT BEAUTIFUL LATE SUMMER AFTERNOON COMING TO AN END...LEAVING WHAT WILL BE ONE OF THE COOLER NIGHTS THIS AREA HAS SEEN IN QUITE SOME TIME. COLD FRONT CONTINUES TO SAG WELL SOUTH OF THE AREA...AND HAS PUSHED TO NEARLY THE FLORIDA STATE LINE TODAY. DRIVING THIS BOUNDARY IS A STRONG RIDGE OF HIGH PRESSURE OF CANADIAN ORIGIN...WITH THE CENTER OF THIS HIGH ACTUALLY WELL NORTH OF WINNIPEG, CANADA IN THE NORTH CENTRAL PART OF THE COUNTRY. THIS HIGH IS RIDGING INTO NEW ENGLAND AND THEN DOWN THE EASTERN SEABOARD...WITH ABNORMALLY COOL AND DRY AIR FOR LATE AUGUST FILTERING INTO THE REGION. THIS AIR MASS IS VERY FALL-LIKE...AND DEWPOINTS HAVE FALLEN INTO THE LOW AND MID 60S AREA-WIDE TODAY. THIS DRY AIR HAS LIMITED TOTAL INSTABILITY...AND ALTHOUGH HIGH-RES GUIDANCE CONTINUES TO SUGGEST THE POTENTIAL FOR ISOLATED SEA-BREEZE SHOWERS THROUGH THIS EVE...THE CHANCE FOR THAT IS WANING...AND EVEN DIURNAL CU IS HAVING TROUBLE GAINING MUCH AGITATION. STILL CONTINUED JUST VERY SCHC ALONG THE SC PORTION OF THE SEA BREEZE FOR THE NEXT FEW HOURS. IF A SHOWER DOES DEVELOP IT WILL ERODE QUICKLY AFTER DARK...AS WILL THE MAJORITY OF THE CLOUD COVER. NE WINDS WILL REMAIN ELEVATED TONIGHT...LIKELY STAYING 5-10 MPH INTO MONDAY MORNING. THESE WINDS WILL CONTINUE TO ADVECT COOL/DRY AIR...THUS DRIVING MINS WELL BELOW 70...WITH LOWER 60S ENCOMPASSING THE NORTHERN HALF OR 2/3 OF THE CWA. WHILE ELEVATED WINDS TEND TO LIMIT OVERALL COOLING...NE WINDS HAVE A TENDENCY TO COOL THE AREA MORE THAN WOULD TYPICALLY BE EXPECTED...ESPECIALLY ACROSS THE CAPE FEAR REGION. FOR THIS REASON HAVE FORECAST THE LOWEST TEMPS IN THE NE ZONES TONIGHT...AND WILMINGTON MAY SEE ITS COOLEST NIGHT SINCE EARLY JUNE. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/... AS OF 300 PM SUNDAY...THE FORECAST AREA WILL REMAIN IN THE GRIP OF AN UNSEASONABLE NE FLOW AS HIGH PRESSURE CENTERED ACROSS THE NORTHEAST U.S. RIDGES SOUTH...WITH ITS AXIS REMAINING TO THE WEST OF OUR FORECAST AREA. AT THE SAME TIME...SLOW STRENGTHENING OF THE VERY SLOW MOVING TROPICAL STORM ACROSS THE BAHAMAS IS EXPECTED. THIS WILL SERVE TO PROLONG THE RATHER TIGHT PRESSURE GRADIENT BETWEEN THESE TWO SYSTEMS. AS THESE NE WINDS PERSIST...THEY WILL SERVE TO PILE UP WATER ON THE IMMEDIATE COAST. THIS IN COMBINATION WITH THE NEW MOON WILL INCREASE THE RISK FOR MINOR BEACH EROSION FOR THOSE BEACHES EXPOSED TO A NE FETCH AND MINOR COASTAL FLOODING DURING THE NIGHTTIME HIGH TIDE... BOTH AT THE BEACHES AND ALONG THE LOWER CAPE FEAR RIVER. OTHER HAZARDS WILL INCLUDE A STRONG LONG SHORE CURRENT...MODERATE TO PERHAPS STRONG RIP CURRENTS AND HIGHER THAN NORMAL...ROUGH SURF. TEMPS WILL BE COOL IN THIS BREEZY NE FLOW REGIME. HIGHS WILL BE IN THE LOWER TO MID 80S...WITH TUE PERHAPS SLIGHTLY COOLER THAN MON. LOWS WILL BE IN THE LOWER TO MID 60S WITH PERHAPS UPPER 60S AT THE BEACHES. WIND SPEEDS ON MON WILL BE UP TO 10 TO 20 MPH WITH HIGHER GUSTS...ESPECIALLY AT THE BEACHES. OFFSHORE SHOWERS ARE EXPECTED TO REMAIN THERE FOR MUCH OF THE PERIOD. TRAJECTORIES WILL AT TIMES BRING THE SHOWERS VERY NEAR THE BEACHES...BUT GIVEN THE DRYNESS OF THE COLUMN...EXPECT THESE SHOWERS TO LARGELY ERODE BEFORE MOVING ONSHORE. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 300 PM SUNDAY...THE MID LEVEL PATTERN WILL SHOW TYPICAL LATE SUMMER LETHARGY THROUGH THE PERIOD AS RIDGING WILL BE THE CENTRAL THEME. THE AXIS OF THE RIDGE MOVES FROM THE MISSISSIPPI VALLEY TO OFF THE PENINSULA OF FLORIDA BY THE END OF THE PERIOD. AT THE SURFACE...WEAK HIGH PRESSURE WILL PREVAIL AS WELL AND AS THE MID LEVEL RIDGE REPOSITIONS...A RELATIVELY WEAK BACKDOOR FRONT WILL MOVE ACROSS FRIDAY. THIS WILL SERVE TO ENHANCE THE POPS BOTH FRIDAY AND SATURDAY. HOWEVER MOISTURE AND FORCING REMAIN RELATIVELY WEAK AND SLIGHT CHANCE FRIDAY TO LOW CHANCE SATURDAY WILL SUFFICE FOR NOW. THERE IS ALSO SLIGHT CHANCE POPS FOR WEDNESDAY AND THURSDAY ALONG THE COASTAL AREAS. THE COOL REFRESHING AIRMASS WILL BE A THING OF THE PAST AS TEMPERATURES WEDNESDAY THROUGH FRIDAY WILL BE AT OR JUST ABOVE CLIMATOLOGY. FOR NEXT WEEKEND...A SLIGHT DROP IN TEMPERATURES IS SEEN AS THE BACKDOOR FRONT MOVES ACROSS BUT JUST A COUPLE OF DEGREES. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 06Z...VFR WILL PREVAIL THROUGH THIS TAF PERIOD. OTHER THAN THE POSSIBILITY OF SOME MVFR STRATOCU CLIPPING THE COASTAL TERMS EARLY THIS MORNING...MOSTLY CLEAR CONDITIONS WILL PERSIST THROUGH THE OVERNIGHT HOURS. SREF PROBABILITIES CONTINUE TO DEPICT THE MVFR CIGS STAYING WELL OFFSHORE...SO NO MENTION OF REDUCED CIGS IN THE TAFS. NORTHEAST WINDS AROUND 10 KT WILL STRENGTHEN TO 10-15 KT WITH GUSTS UP TO 20 KT AS HIGH PRESSURE CONTINUES WEDGING INTO THE CAROLINAS TODAY. LOW LEVEL MOISTURE WILL REMAIN TRAPPED BENEATH THE SUBSIDENCE INVERSION...SO EXPECT SCT 3-7KFT CU TO DEVELOP AGAIN DURING THE DAY. BUT WITH EXTREMELY DRY AIR IN PLACE ABOVE 700 MB...THERE IS NO PCPN IN THE FORECAST THROUGH THE END OF THE PERIOD. EXTENDED OUTLOOK...EXPECT VFR CONDITIONS THROUGH THE EXTENDED PERIOD. SLIGHT CHANCE OF SHOWERS FOR OUR NORTHERN TERMINALS FRI. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1:30 AM MONDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSIONS FOLLOW: WIND SPEEDS ARE RUNNING JUST A BIT HIGHER THAN FORECAST NEARSHORE BUT LOOK GOOD OFFSHORE COMPARED TO BUOYS 41037 AND 41004. MARINE MOS GUIDANCE AND LATEST RUC AND HRRR MODELS SUGGEST WIND SPEEDS WILL BACK MORE NORTHERLY OVERNIGHT BUT WILL NOT DECREASE MUCH IN SPEED. IN FACT THE ADVECTION OF COOLER AIR OVER THE VERY WARM OCEAN SURFACE LATER TONIGHT WILL PROBABLY ENHANCE GUSTINESS AND DOWNWARD TRANSPORT OF STRONGER WINDS FROM ALOFT. NO SIGNIFICANT CHANGES WERE MADE TO THE FORECAST OVERNIGHT. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS... PINCHING NE GRADIENT EAST OF A RIDGE OF HIGH PRESSURE EXPANDING DOWN THE COAST IS CAUSING DETERIORATING MARINE CONDITIONS TODAY. WINDS ARE SLOWLY BUT STEADILY RISING OUT OF THE NE...WITH SPEEDS OF 15-20 KTS COMMON ACROSS THE WATERS...WITH SOME GUSTS APPROACHING 30 KTS DEVELOPING OVER THE NORTHERN WATERS AND OUTSIDE OF 20 NM. AS THE HIGH PRESSURE STRENGTHENS TONIGHT...THE GRADIENT WILL TIGHTEN FURTHER...AIDED BY THE DISTANT BUT STRENGTHENING TROPICAL STORM CRISTOBAL NEAR THE BAHAMAS. THIS WILL CAUSE WIDESPREAD 15-25 KT NE WINDS THROUGH THE PERIOD...WITH SEAS BUILDING TO 5-8 FT. WAVE HEIGHTS WILL BE DRIVEN ALMOST ENTIRELY BY A NE WIND CHOP TONIGHT. HOWEVER...LONGER PERIOD SWELL ASSOCIATED WITH TROPICAL STORM CRISTOBAL IS FORECAST TO BEGIN TO ENTER THE SPECTRUM TONIGHT. ONLY NOTICEABLE LONG-SWELL PRESENTLY EXISTS AT 41004 /EDISTO BUOY/ WHICH IS OBSERVING A LOW-AMPLITUDE 13 SEC SWELL. EXPECT THIS TO GRADUALLY LIFT NE INTO THE LOCAL WATERS...BUT HAVE ONLY MINIMAL CONTRIBUTION TO THE SIGNIFICANT SEAS UNTIL MONDAY. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 PM SUNDAY...THE PRESSURE DIFFERENCE BETWEEN HIGH PRESSURE TO THE NORTH AND A SLOWLY DEVELOPING TROPICAL STORM ACROSS THE BAHAMAS WILL KEEP A TIGHT PRESSURE GRADIENT ACROSS THE WATERS. A SMALL CRAFT ADVISORY REMAINS IN EFFECT. WINDS WILL COMMONLY BE SUSTAINED AT 20 TO 25 KT. THE LONG NE FETCH WILL KEEP SEAS IN THE 4 TO 7 FT RANGE WITH AT LEAST 8 FT SEAS BEYOND 20 NM. A 10 TO 12 SECOND SE SWELL IS EXPECTED TO SLOWLY BUILD THROUGH THE PERIOD. LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 300 PM SUNDAY...CONFIDENCE CONTINUES TO BUILD THAT THE ONLY IMPACTS FROM CRISTOBAL WILL BE THE SWELL COMPONENT ADDED TO THE WAVE SPECTRUM. THE LATEST WAVEWATCH HURRICANE BULLETIN FOR FRYING PAN SHOALS SHOWS 7-8 FEET DEVELOPING OR PERSISTING WEDNESDAY THROUGH EARLY THURSDAY WITH A GOOD PORTION OF THIS BEING THE WIND WAVE COMPONENT. THIS MAKES SENSE AS THE GFS IS NOT DEVELOPING THE SYSTEM APPRECIABLY. FOR THE 0-20 MILE COASTAL WATERS 4-6 FEET WEDNESDAY AND EARLY THURSDAY SHOULD SUFFICE. BY FRIDAY A WEAK PRESSURE PATTERN YIELDS LIGHT WINDS AND SEAS. FOR THE WINDS WEDNESDAY AND THURSDAY...A NORTHEASTERLY FLOW OF 10-15 KNOTS WEDNESDAY DROPS TO SINGLE DIGITS THURSDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT TUESDAY FOR AMZ250-252-254- 256. && $$ SYNOPSIS...RJD NEAR TERM...REK/TRA/JDW SHORT TERM...RJD LONG TERM...SHK AVIATION...REK/BJR MARINE...REK/RJD/TRA/JDW/SHK
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
1209 AM CDT MON AUG 25 2014 .UPDATE... /ISSUED 902 PM CDT SUN AUG 24 2014/ SKIES ARE MOSTLY CLEAR OVER MUCH OF THE FORECAST AREA THIS EVENING WITH TEMPERATURES RANGING FROM THE LOWER 70S TO MID 80S. ALL OF THE THUNDERSTORM ACTIVITY THAT WAS OVER THE FORECAST AREA EARLIER THIS EVENING HAS ENDED AND NO ADDITIONAL THUNDERSTORMS ARE EXPECTED FOR THE REMAINDER OF TONIGHT. WILL UPDATE FORECAST TO REMOVE ANY MENTION OF RAIN TONIGHT. ARS && .DISCUSSION... /ISSUED 615 PM CDT SUN AUG 24 2014/ NQA RADAR BACK IN SERVICE AND JUST IN TIME TO SHOW CONVECTION DEVELOPING IN NORTH MISSISSIPPI. TEMPERATURES WERE MAINLY IN THE 90S ACROSS THE MIDSOUTH WITH A RECORD 100 DEGREES...THE WARMEST READING SINCE AUGUST 2012...AT THE MEMPHIS INTERNATIONAL AIRPORT. FOR THE REMAINDER OF TODAY AND TONIGHT...SHORT TERM HRRR MODEL SHOWING CONVECTION BECOMING SCATTERED BY 4 PM FOR POINTS ALONG AND WEST OF THE MISSISSIPPI RIVER...WHICH CURRENTLY LINES UP WITH PW`S ABOVE 1.80 INCHES. COULDN`T RULE OUT AN ISOLATED WET MICROBURST WITH THE STRONGEST STORMS. ACTIVITY WILL WANE BY 9 PM LEAVING SKIES PARTLY CLOUDY OVERNIGHT. THIS SHOULD HELP KEEP MORE HEAT IN...WITH OVERNIGHT LOWS AGAIN IN THE MID AND UPPER 70S. MONDAY AND TUESDAY...A WEAK DISTURBANCE WILL MOVE WESTWARD ALONG THE GULF COAST/SOUTHSIDE OF THE UPPER RIDGE...AND AS IT DOES EASTERLY WINDS IN THE BOUNDARY LAYER AND MIDLEVELS WILL SLIDE DRIER AIR OFF THE APPALACHIANS IN ITS WAKE. HEAT INDICES WILL CONTINUE TO FLIRT WITH 105F TOMORROW...DESPITE MORE CLOUD COVER AND CONVECTION. FEEL BY TUESDAY ENOUGH DRY AIR WILL HAVE OVERSPREAD THE MIDSOUTH TO REDUCE HEAT INDICES BELOW 105F. ISOLATED STORMS WILL BE POSSIBLE ON TUESDAY BUT MAINLY WEST OF THE MISSISSIPPI RIVER NEAR THE FRONT EDGE OF THE DRIER AIR. WEDNESDAY THROUGH FRIDAY...MODELS ARE IN GOOD AGREEMENT THAT THE UPPER RIDGE WILL REMAIN OVER THE REGION...BUT STRONGER SUBSIDENCE WILL KEEP DEWPOINTS IN THE 60S AND LOWER RAIN CHANCES TO AROUND 10 PERCENT. TEMPERATURES WILL BE IN THE LOW TO MID 90S WITH AFTERNOON HEAT INDICES IN THE 93-100F RANGE. NEXT WEEKEND...THE GFS AND EURO ARE BECOMING BETTER ALIGNED THAT THE RIDGE WILL FLATTEN IN RESPONSE TO AN APPROACHING CENTRAL PLAINS SHORTWAVE. THIS DISTURBANCE NOW APPEARS SOMEWHAT WEAKER AND OUT OF PHASE WITH THE MAIN UPPER LEVEL FLOW. NONETHELESS MOISTURE OUT AHEAD OF THE SYSTEM WILL MOVE OVER THE OZARKS ON SATURDAY AND INTO THE MIDSOUTH BY EARLY SUNDAY. HAVE BUMPED UP TEMPERATURES TO MAINLY THE LOW 90S FOR HIGHS AND KEPT A CONSERVATIVE APPROACH TO THE RAIN CHANCES. JAB && .AVIATION... 06Z TAF CYCLE ISOLATED TO SCATTERED TSRA ARE EXPECTED TO DEVELOP MONDAY AFTERNOON AROUND THE KMEM...KMKL...AND KTUP TAF SITES...MENTIONED VCTS FOR THESE SITES. OTHERWISE VFR CONDITIONS WILL PREVAIL DURING THE PERIOD...THE EXCEPTION POSSIBLY BEING MVFR CONDITIONS IN FOG AT KMKL EARLY MONDAY MORNING. WINDS TONIGHT EASTERLY 5 KTS OR LESS. WINDS MONDAY E-SE 4-6 KTS. WINDS MONDAY NIGHT E 5 KTS OR LESS. JCL/KRM && && .MEG WATCHES/WARNINGS/ADVISORIES... AR...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR CLAY-CRAIGHEAD- CRITTENDEN-CROSS-GREENE-LAWRENCE-LEE AR-MISSISSIPPI- PHILLIPS-POINSETT-RANDOLPH-ST. FRANCIS. MO...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR DUNKLIN-PEMISCOT. MS...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ALCORN-BENTON MS- CALHOUN-CHICKASAW-COAHOMA-DESOTO-ITAWAMBA-LAFAYETTE-LEE MS- MARSHALL-MONROE-PANOLA-PONTOTOC-PRENTISS-QUITMAN- TALLAHATCHIE-TATE-TIPPAH-TISHOMINGO-TUNICA-UNION-YALOBUSHA. TN...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR BENTON TN-CARROLL- CHESTER-CROCKETT-DECATUR-DYER-FAYETTE-GIBSON-HARDEMAN- HARDIN-HAYWOOD-HENDERSON-HENRY-LAKE-LAUDERDALE-MADISON- MCNAIRY-OBION-SHELBY-TIPTON-WEAKLEY. && $$
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1133 PM CDT SUN AUG 24 2014 .AVIATION... VFR CONDITIONS SHOULD PREVAIL FOR THE NEXT 24 HOURS. TSRA ACTIVITY IS EXPECTED ACROSS THE AREA MONDAY AFTERNOON AND EVENING...BUT WILL MOST LIKELY REMAIN WEST OF BOTH TERMINALS. LIGHT EASTERLY SURFACE WINDS EARLY THIS MORNING SHOULD BECOME SOUTHERLY BUT REMAIN AROUND 12 KTS OR LESS DURING THE DAY. && .PREV DISCUSSION... /ISSUED 725 PM CDT SUN AUG 24 2014/ UPDATE... QUICK UPDATE TO ADJUST POP/WX/QPF GRIDS THROUGH THIS EVENING TO BETTER CORRESPOND TO CURRENT RADAR TRENDS. MOST NOTABLY... INCREASED POPS INTO THE CHANCE AND LIKELY CATEGORIES ACROSS A GOOD PORTION OF THE ROLLING PLAINS WHERE A POORLY ORGANIZED CLUSTER OF CONVECTION CONTINUES. WE EXPECT AN OVERALL DOWNWARD TREND IN THE CONVECTION THROUGH THE MID/LATE EVENING HOURS AS THE UNSTABLY AND DIURNALLY DRIVEN FORCING WANES. PREV DISCUSSION... /ISSUED 636 PM CDT SUN AUG 24 2014/ AVIATION... CURRENT RADAR TRENDS SUGGEST THAT KLBB AND KCDS MAY ESCAPE ANY -TSRA IN THE NEXT HOUR OR SO...BUT THERE IS STILL AN OUTSIDE CHANCE. ALSO...SOME GUSTY OUTFLOW WINDS ARE STILL POSSIBLE. OTHERWISE...VFR CONDITIONS WITH SRLY SURFACE WINDS EXPECTED THROUGH MID-AFTERNOON MONDAY. PREV DISCUSSION... /ISSUED 343 PM CDT SUN AUG 24 2014/ SHORT TERM... DESPITE OF A WESTWARD EXPANSION OF WEAK RIDGING ALOFT AND VERY LITTLE IF ANY SURFACE FEATURES...AN ADEQUATE BOOST IN THETA-E EARLIER TODAY SUPPLIED MUCH OF THE AREA WITH DEEPER MOISTURE NECESSARY FOR SOME DIURNALLY DRIVEN TSTORMS. NON-HIGH RES MODELS HAVE LARGELY MISSED THE BOAT SO FAR TODAY WITH THE EXPERIMENTAL MODELS PLAYING THE ROLE OF THE DARK HORSE. RAP DATA SHOW THE RICHEST PWATS OF 1.3 INCHES CONFINED EAST OF A BROWNFIELD TO SILVERTON LINE WITH GENERALLY ONE INCH OR LESS FARTHER WEST. ENVIRONMENT IN THE RICHER PWATS IS CHARACTERIZED BY SBCAPES OF 1200-2500 J/KG WITH WEAK SHEAR. THIS THEME WILL PERSIST THROUGH MID-EVENING AT WHICH POINT TSTORMS WILL DWINDLE...BUT UNTIL THEN WE EXPECT ADDITIONAL STRONG TO PERHAPS BRIEFLY SEVERE PULSE MODES WITH MICROBURSTS THE PRIMARY HAZARD. BY MONDAY MORNING...DEEPER MONSOONAL MOISTURE WILL BE TUGGED NORTH INTO NEW MEXICO AROUND THE ZONAL RIDGE AXIS STILL POISED FIRMLY OVER THE SOUTH PLAINS. HEIGHT FIELDS ON THE WESTERN PERIPHERY OF THIS RIDGE ARE NOT SHOWN TO BUILD ANY...SO THE OPPORTUNITY WILL EXIST FOR ANOTHER ROUND OF SOLAR-POWERED TSTORMS MAINLY NEAR THE NM STATE LINE WHERE OCCASIONAL DISTURBANCES ARE PROGGED TO LIFT NORTH FROM CHIHUAHUA. OTHERWISE...WE CONTINUE TO SIDE WITH THE WARMER SPECTRUM OF MOS GUIDANCE FOR BOTH LOWS AND HIGHS GIVEN THE RECENT OBSERVED TRENDS. LONG TERM... COOLER WEATHER IS ON THE WAY AS WELL AS A SHOT FOR RAIN. BUT BEFORE WE GET THERE...WARM AND DRY WEATHER WILL CONTINUE TO DOMINATE US AS HIGH PRESSURE TO OUR EAST EXTENDS OVER THE REGION. OUR NORTHWESTERN ZONES WILL HAVE A BIT OF A REPRIEVE MONDAY NIGHT AS A WEAKNESS PROPAGATES AROUND THE WESTERN EDGE OF THE RIDGE. THE WEAKNESS MAKES USE OF A SURFACE TROF LOCATED OVER THE SOUTHWESTERN TX PANHANDLE AND FIRES SCATTERED CONVECTION IN THAT REGION. CHANCES ARE ONLY SLIGHT AS THE AVAILABLE MONSOONAL MOISTURE ONLY COVERS A VERY SMALL AREA WHICH COINCIDES WITH THE SURFACE TROF. BY TUESDAY AND INTO WEDNESDAY...THE RIDGE TO OUR EAST BUILDS FURTHER WEST INHIBITING CHANCES FOR ANY RAIN...HOWEVER A LOW AWAITS US OVER THE GREAT BASIN AND IS READY TO MOVE IN AND DEFEAT THE EVIL RIDGE. WITH THE EXCEPTION OF THE GFS...MODELS HAVE BEEN IN DECENT AGREEMENT WITH HANDLING OF THE LOW THE PAST SEVERAL RUNS. THE 12Z RUN YIELDED THE GFS SLOWING THE EASTWARD PROGRESSION OF THE LOW AND IS MORE IN LINE WITH THE OTHER MODELS. THE LOW WILL INITIALLY START OFF CLOSED AS IT MOVES ACROSS THE ROCKIES INTO THE CENTRAL PLAINS DURING WHICH TIME IT WILL SLOWLY BECOME AN OPEN WAVE. BY LATE WEDNESDAY A COLD FRONT SHOULD BE KNOCKING ON OUR DOOR. THE TIMING OF THE FRONT IS SOMEWHAT IN QUESTION WITH TIMINGS RANGING FROM EARLY TO LATE THURSDAY...WITH THURSDAY MORNING BEING THE TIMING CHOICE FOR THE TIME BEING. RAIN CHANCES WILL EXIST ALONG THE FRONT...ESPECIALLY AS THE UPPER LEVEL LOW PUSHES INTO THE REGION. PWATS OVER 1.3 INCHES WILL BE MORE THAN ENOUGH TO AID IN MODERATE RAINFALL AMOUNTS. RAIN CHANCES WILL BE HIGHEST THURSDAY NIGHT INTO EARLY FRIDAY AS A JET MAX PUSHES IN FROM THE WEST ON THE SOUTHEAST SIDE OF THE LOW. AS OF NOW THE JET MAX IS GREATEST OVER OUR SOUTHEASTERN ZONES. THIS COMBINED WITH A DIFFLUENT UPPER PATTERN SHOULD BE MORE THAN EFFICIENT IN DEVELOPING PRECIP. THE LOW WILL HAVE AN EXTENDED VISIT AND REMAIN OVERHEAD THROUGH LATE SUNDAY BEFORE ZONAL FLOW TAKES OVER. TEMPERATURES WILL BE RELATIVELY COOL IN THE SENSE OF TEMPS WILL BE AROUND SEASONAL AVERAGES BUT COOLER THAN THEY WILL BE EARLIER THIS WEEK. DEPENDING ON THE STRENGTH OF THE FRONT...SOME AREAS SUCH AS THE TEXAS PANHANDLE MAY SEE BELOW AVERAGE TEMPS AS COOL AIR OVER MT INTO CA WILL BE PUSHED SOUTHWARD. AS OF THIS AFTERNOON...PARTS OF INTERIOR MT HAVE FAILED TO REACH INTO THE 50S. AS OF NOW THE COOLEST AIR WITH THE FRONT LATER THIS WEEK SHOULD STAY TO OUR NORTH WITH THE COOL SIDE OF THE FORECAST BEING IN THE UPPER 50S. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 65 92 63 90 62 / 10 20 20 10 10 TULIA 69 95 65 93 64 / 10 10 20 10 10 PLAINVIEW 65 95 64 92 64 / 10 10 10 10 10 LEVELLAND 67 94 65 91 64 / 10 10 20 10 10 LUBBOCK 72 96 68 94 68 / 10 10 10 10 10 DENVER CITY 67 95 65 92 65 / 10 10 10 10 10 BROWNFIELD 66 96 66 93 66 / 10 10 10 10 10 CHILDRESS 73 101 72 98 72 / 20 10 10 10 10 SPUR 70 100 68 96 68 / 20 0 10 0 10 ASPERMONT 75 102 72 99 71 / 60 0 10 0 10 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 33
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1154 PM CDT SUN AUG 24 2014 UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE .SHORT TERM...TONIGHT AND MONDAY ISSUED AT 243 PM CDT SUN AUG 24 2014 THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW UPPER LEVEL LOW PRESSURE OVER EASTERN MONTANA AND A DOUBLE BARRELED SURFACE LOW OVER NORTH DAKOTA. A WARM FRONT EXTENDS FROM THIS SURFACE LOW OVER SOUTHWEST WISCONSIN...WHICH MARKS THE TRANSITION FROM MOSTLY CLOUDY SKIES TO CLEAR CONDITIONS. A COLD FRONT EXTENDS SOUTHWARD OVER THE CENTRAL PLAINS AND IS LARGELY INACTIVE AT THIS HOUR THOUGH THAT MIGHT BE CHANGING OVER CENTRAL MINNESOTA WHERE ML CAPES HAVE EXCEEDED 2000 J/KG. A FEW OTHER ELEVATED STORMS CONTINUE TO DEVELOP OVER NORTHWEST WISCONSIN WITHIN THE TAIL END OF A VORT MAX. WILL ADD A CHANCE TO N-C WISCONSIN BETWEEN 21Z AND 00Z. AS THE UPPER LOW AND COLD FRONT MOVE EAST...THUNDERSTORM AND SEVERE WEATHER CHANCES ARE THE MAIN FORECAST CONCERNS. TONIGHT...THE LARGE UPPER LOW WILL MOVE ACROSS NORTH DAKOTA INTO THE LAKE WINNIPEG REGION. MID-LEVEL HEIGHT FALLS FROM THE SYSTEM WILL MOVE INTO THE WESTERN GREAT LAKES...WHICH WILL HELP PUSH A WEAK COLD FRONT INTO WESTERN WISCONSIN AFTER MIDNIGHT. CONVERGENCE ALONG THE FRONT IS RELATIVELY WEAK...BUT ELEVATED INSTABILITY APPROX 1000-1500 J/KG (ROUGH ESTIMATE) WILL MOVE INTO CENTRAL AND NORTH-CENTRAL WISCONSIN AFTER MIDNIGHT. BECAUSE OF THE WEAK FORCING...KEPT CHANCES OF PRECIP IN THE SCATTERED RANGE. THE MAGNITUDE OF CAPE AND WIND SHEAR AROUND 30 KTS WOULD SUPPORT A CHANCE OF STRONG STORMS THAT COULD PRODUCE NEAR SEVERE HAIL AND WIND GUSTS. WILL LEAVE A MENTION OF THIS POSSIBILITY IN THE HWO. THE MESO MODELS CONTINUE TO SHOW CONVECTION DEVELOPING OVER CENTRAL MINNESOTA LATER THIS AFTERNOON BEFORE TRACKING THE STORMS INTO NORTH-CENTRAL WISCONSIN AFTER 06Z. THIS STILL SEEMS POSSIBLE BASED ON THE DESTABILIZATION TAKING PLACE OVER CENTRAL MINNESOTA. THE STORMS SHOULD WEAKEN AS THEY MOVE EAST LATE TONIGHT DUE TO DIMINISHING INSTABILITY. OTHERWISE...LOOK FOR A MUGGY EVENING WITH LOWS DROPPING INTO THE MIDDLE AND UPPER 60S. MONDAY...THE FRONT WILL MAKE LITTLE PROGRESS TO THE EAST AND INTO NORTH-CENTRAL WISCONSIN DURING THE AFTERNOON. SPOTTY SHOWERS AND STORMS WILL BE POSSIBLE AHEAD OF THE FRONT DURING THE MORNING ACROSS MUCH OF THE AREA. ASSUMING COVERAGE IS NOT MORE THAN ADVERTISED...LOW LEVEL SOUTHWEST WINDS WILL PUSH TEMPS INTO THE UPPER 80S OR LOWER 90S OVER THE EASTERN FORECAST AREA. COMBINED WITH DEWPOINTS AROUND 70 DEGREES...ML CAPES ARE PROJECTED TO REACH 2K-3K J/KG WITH BULK SHEARS AROUND 30 KTS. CONVERGENCE ALONG THE FRONT WILL REMAIN WEAK BUT CANNOT RULE OUT ISOLATED OR SCATTERED STRONG TO SEVERE STORMS OVER THE EAST DURING THE AFTERNOON WITH THAN KIND OF INSTABILITY AND SHEAR. DRIER MID-LEVEL AIR WILL WORK INTO CENTRAL AND NORTH-CENTRAL WISCONSIN DURING THE AFTERNOON...WHICH WILL MAKE IT HARDER FOR STORMS TO INITIATE. THE COMBINATION OF HEAT AND HUMIDITY WILL PUSH HEAT INDICES INTO THE MIDDLE 90S. .LONG TERM...MONDAY NIGHT THROUGH SUNDAY ISSUED AT 243 PM CDT SUN AUG 24 2014 MODELS CONTINUE TO INDICATE A RATHER AMPLIFIED MEAN FLOW PATTERN ACROSS THE CONUS WITH AN UPPER TROF CURRENTLY OVER THE INTER MOUNTAIN WEST AND SIG RIDGE OVER THE EASTERN LAKES. THE MOVEMENT OF UPPER LOW OUT OF TROF INTO THE WESTERN LAKES EARLY IN THE PERIOD WILL BE THE PRIMARY WEATHER FEATURE TO IMPACT OUR WEATHER. BY LATE THIS WEEK...MODELS CONTINUE TO SHOW LINGERING PIECE OF TROF MEANDERING INTO THE CENTRAL U.S. THE MOVEMENT OF THIS FEATURE CONTINUES TO SLOW AS IT REMAINS CUT OFF FROM MAIN BAND OF WESTERLIES EXPECTED TO LIE OVER SOUTHERN CANADA. FORECAST CONFIDENCE LOW THU NIGHT ONWARD. TREND IN SHORTER RANGE IS TO CONTINUE TO SLOW PASSAGE OF COLD FRONT MONDAY WITH FRONT STILL BISECTING CWA AT 00Z TUE. HAVE CONTINUE SCATTERED/CHANCE POPS MAINLY SOUTH AND EAST GIVEN AVAILABLE INSTABILITY. LITTLE DYNAMICS BESIDES FRONT TO SUPPORT GOING ANY HIGHER WITH POPS. CONSISTENCY SEEN IN MODELS TO PUSH FRONT AND PCPN MAINLY SOUTH OF CWA AS HIGH PRESSURE AND DRIER AIR MASS MOVES IN OVER NORTHERN WI TUE INTO THU. CONCERN THIS PERIOD ON TEMPS. DRIER AIR...SUN AND LOW LEVEL TEMPS AT OR SLIGHTLY BELOW NORMAL SHOULD SUPPORT TEMPS IN THE LOWER TO MIDDLE 70S. WILL HAVE EAST FLOW OFF LAKE THOUGH LAKE SURFACE TEMPS NOW IN MID TO UPPER 60S SO HAVE CONFINED COOLING TO CLOSER TO THE COAST. HAVE BUMPED MAX TEMPS UP A BIT MID WEEK. && .AVIATION...FOR 06Z TAF ISSUANCE ISSUED AT 1153 PM CDT SUN AUG 24 2014 AN AREA OF SHOWERS AND THUNDERSTORMS WILL MOVE ACROSS THE AREA OVERNIGHT. THE ACTIVITY WILL PROBABLY ARRIVE IN RHINELANDER AND WAUSAU BETWEEN 07 AND 09Z AND AT APPLETON... OSHKOSH AND GREEN BAY BETWEEN 11Z AND 13Z IF IT HOLDS TOGETHER. MVFR CEILINGS ARE A EXPECTED IN MOST PLACES WITH LOCAL IFR IN THE NORTH. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TE AVIATION.......RDM
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
1023 PM MDT SUN AUG 24 2014 .SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT) ISSUED AT 345 PM MDT SUN AUG 24 2014 QUIET DAY TODAY WITH FAIR WEATHER CU DEVELOPING ACROSS THE AREA. DEEP MIXING AND GUSTY WESTERLY WINDS HAVE RESULTED IN QUITE A BIT OF DRIER AIR ALOFT MIXING DOWN TO THE SURFACE THIS AFTERNOON...WITH NO DEEP CONVECTION OBSERVED. THE UPPER LEVEL LOW WHICH BROUGHT RAIN AND TSTORMS TO THE AREA THE LAST FEW DAYS HAS MOVED INTO NORTH DAKOTA AND WILL EVENTUALLY PUSH INTO CANADA...WHILE THE NEXT WEATHER CONCERN FOR THIS WEEK IS CURRENTLY DIGGING SOUTH ACROSS THE PACIFIC NORTHWEST. THIS IS THE NEXT UPPER LEVEL TROUGH TO LIKELY IMPACT THE FORECAST AREA AND WILL EVENTUALLY BECOME AN UPPER LEVEL LOW NEAR THE CENTRAL ROCKY MOUNTAINS BY THE MIDDLE OF THE WEEK. BEFORE THEN...THIS SYSTEM WILL PRIMARILY ALLOW THE JET STREAM TO SHIFT BACK TO THE NORTH AND INTENSIFY OVER THE AREA TONIGHT. THERE IS A POTENTIAL FOR NOCTURNAL CONVECTION...INCLUDING THUNDERSTORMS...TONIGHT ACROSS THE SOUTHERN HALF OF THE FORECAST AREA...MAINLY SOUTH OF THE NORTH PLATTE RIVER VALLEY. THE UPPER LEVEL TROUGH WILL DIG SOUTH INTO THE GREAT BASIN ON MONDAY. MODELS HAVE CONTINUED TO TREND SLOWER AND MORE AMPLIFIED WITH THIS SYSTEM OVER THE LAST 3 DAYS AS THE TROUGH BECOMES A CLOSED LOW SOMEWHERE BETWEEN NORTHERN NEVADA AND NORTHWEST COLORADO. THE ECMWF AND GEM CONTINUE TO BE THE SLOWEST...WITH THE GFS AND NAM NOT TOO FAR BEHIND NOW SINCE BOTH SOLUTIONS ARE TRENDING TOWARDS THE ECMWF. WITH DECENT LOW TO MIDLEVEL INSTABILITY...MOISTURE ADVECTION...AND CAPE OVER 1000 J/KG...EXPECT AFTERNOON SHOWERS AND TSTORMS TO DEVELOP ACROSS MOST OF THE AREA. WITH THE LACK OF A DEFINED SHORTWAVE...DO NOT EXPECT WIDESPREAD COVERAGE. IN FACT...MOST OF THE PANHANDLE MAY NOT SEE ANY ACTIVITY AT ALL DUE TO THE CAP INVERSION AT 750 MB. KEPT ISOLATED TSTORMS OVER THAT AREA AT BEST DURING THE AFTERNOON...BUT MAY SEE AN INCREASE IN SHOWERS AND TSTORMS IN THE EVENING HOURS. A FEW THUNDERSTORMS MAY BECOME STRONG OVER SOUTHEAST WYOMING. HIGH TEMPERATURES WILL STRUGGLE TO REACH THE MID TO UPPER 70S ACROSS MOST OF THE AREA DUE TO INCREASING SOUTHEAST WINDS. SLOW MOVING CLOSED LOW WILL BARELY MAKE IT INTO WESTERN UTAH BY TUESDAY...WITH ANOTHER DAY OF THUNDERSTORMS EXPECTED. TUESDAY LOOKS TO BE A RATHER WET DAY AND ON THE COOL SIDE. ALTHOUGH THE MAIN LOW WILL BE WELL TO THE WEST...MODELS INDICATE A POTENT SHORTWAVE DISTURBANCE MOVING NORTHWARD OVER THE AREA. THE POSITION AND TIMING OF THIS DISTURBANCE WILL INDICATE WHICH AREAS RECEIVE LOCALLY HEAVY RAINFALL AND THE POTENTIAL FOR SEVERE TSTORMS. INCREASED POP BETWEEN 40 TO 70 PERCENT ACROSS SOUTHEAST WYOMING ON TUESDAY/TUESDAY EVENING. WESTERN NEBRASKA WILL STILL BE STRUGGLING WITH A STRONG CAP INVERSION...SO KEPT POP BELOW 25 PERCENT FROM SIDNEY TO CHADRON. .LONG TERM...(WEDNESDAY THROUGH SATURDAY NIGHT) 12Z MODELS HAVE COME INTO SOME AGREEMENT WITH THE UPPER LEVEL LOW THAT IS EXPECTED TO TRACK ACROSS THE ROCKIES ON WEDNESDAY AND THURSDAY. AS IT STANDS...MODELS CONTINUE TO FAVOR THE SLOWER EAST-SOUTHEAST PROGRESSION OF THE UPPER LOW...TRACKING IT OVER THE ROCKIES THROUGH THURSDAY AND INTO THE CENTRAL PLAINS FRIDAY. THUS WILL CONTINUE TO RELY MORE ON THIS SLOWER SOLUTION FOR THE EXTENDED FORECAST. TEMPS WILL REMAIN BELOW AVERAGE WEDNESDAY AND THURSDAY WITH AT LEAST A CHANCE FOR SCATTERED SHOWERS AND T-STORMS AS THE UPPER LOW MOVES ACROSS WY/CO ON WEDNESDAY. WILL SEE A STEADY DECREASE IN COVERAGE FROM WEST TO EAST THURSDAY. PWATS ARE PROGGED TO BE 0.75 TO 1" OR MORE...AND WITH FAIRLY LIGHT STEERING FLOW OF 10 TO 15 KTS IN PLACE...THIS ACTIVITY COULD BE SLOW MOVING AND PRODUCE HIGH RAIN RATES. THEREFORE FLOODING WILL BE THE MAIN CONCERN WITH THIS SYSTEM. MODELS SHOW H7 TEMPS DROPPING TO 3C OVER THE MOUNTAINS ON WEDNESDAY AS THE LOW CENTER MOVES OVERHEAD...SO ITS VERY POSSIBLE THE HIGH ELEVATIONS ABOVE 10KFT WILL SEE SNOW MIXED IN WITH RAIN. THIS SYSTEM WILL SLOWLY DEPART THE REGION THROUGH THE WEEKEND WITH A WEAK RIDGE BUILDING IN FROM THE WEST FOR FRIDAY AND SATURDAY. A MUCH DRIER AIRMASS WILL MOVE IN WITH THE RIDGE SO CHANCES FOR AFTN SHOWERS AND STORMS WILL BE LOW THROUGH SATURDAY NIGHT. BREEZY CONDITIONS ARE LIKELY ON SATURDAY AS THE LEESIDE SFC PRESSURE TROUGH DEEPENS IN ADVANCE OF THE NEXT SYSTEM DIGGING INTO THE PAC NW FRI NIGHT INTO SATURDAY. TEMPS WILL WARM BACK TO MORE NORMAL READINGS FOR THIS TIME OF YEAR BY SATURDAY AS WELL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY EVENING) ISSUED AT 1020 PM MDT SUN AUG 24 2014 CONVECTION ON THE INCREASE ACROSS NORTHWESTERN COLORADO LATE THIS EVENING. SOME LIGHTNING STRIKES VCNTY OF SARATOGA WYOMING. EXPECT THESE STORMS TO EVENTUALLY MAKE IT INTO KLAR AND KCYS TOWARDS THE 07-08Z TIME FRAME. HRRR SHOWS THIS AREA OF SHOWERS AND THUNDERSTORMS EVENTUALLY MAKING IT INTO THE PANHANDLE TOWARDS 12Z BEFORE DISSIPATING. MORE WIDESPREAD SHOWERS AND THUNDERSTORMS EXPECTED FOR MONDAY AFTERNOON AND EVENING. && .FIRE WEATHER... ISSUED AT 245 PM MDT SUN AUG 24 2014 NO FIRE WEATHER CONCERNS THIS WEEK DUE TO THE UNSETTLED WEATHER PATTERN OVER THE AREA. AFTER A RATHER DRY DAY ON SUNDAY...MOISTURE WILL QUICKLY RETURN TO THE AREA TONIGHT. MINIMUM RELATIVE HUMIDITIES WILL TREND HIGHER...BETWEEN 30 TO 50 PERCENT ALONG WITH EXCELLENT RECOVERIES OVERNIGHT. TEMPERATURES WILL BE COOLER THAN NORMAL ACROSS MOST LOCATIONS THROUGH AT LEAST THURSDAY. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...TJT LONG TERM...RJM AVIATION...CLAYCOMB FIRE WEATHER...TJT
AREA FORECAST DISCUSSION
NWS MIAMI FL
1030 AM EDT MON AUG 25 2014 .UPDATE...A SURFACE TROUGH IS LOCATED ALONG THE PALM BEACH-MARTIN COUNTY LINE AT THIS TIME...AND WILL MOVE SOUTHWEST ACROSS SOUTH FLORIDA TODAY. MOISTURE AND CONVERGENCE ALONG THIS FEATURE...ALONG WITH ADDITIONAL CONVERGENCE AIDED BY THE SEA BREEZES...WILL LEAD TO A GOOD COVERAGE OF THUNDERSTORMS THIS AFTERNOON. A FEW COULD CONTAIN GUSTY WINDS TO AROUND 50 MPH GIVEN THE PRESENCE OF DRY MID LEVEL AIR AND INSTABILITY. THE INHERITED FORECAST LOOKS GOOD WITH CURRENT AND EXPECTED TRENDS, SO NO SIGNIFICANT CHANGES ARE NECESSARY THIS MORNING. WINDS WILL PICK UP BEHIND THIS TROUGH WITH A SMALL CRAFT ADVISORY POSSIBLY NEEDED BY THIS EVENING FOR THE PALM BEACH WATERS. FOLLOW US ON TWITTER @NWSMIAMI. /GREGORIA && .PREV DISCUSSION... /ISSUED 749 AM EDT MON AUG 25 2014/ AVIATION... SURFACE FLOW SHOULD REMAIN NORTHERLY THROUGH THE MORNING TO NORTHEAST BY THE AFTERNOON. A SURGE OF ASSOCIATED MOISTURE WILL KEEP ISOLATED TO SCATTERED SHOWERS PUSHING SOUTH ACROSS THE ATLANTIC WATERS THROUGH THE MORNING. A FEW OF THESE SHOWERS MAY MAKE IT INTO KFXE SOUTHWARD. THEREFORE KEPT VCSH AT THESE TERMINALS THROUGH THE REMAINDER OF THE MORNING. OTHERWISE...VFR CONDITIONS ARE EXPECTED OUTSIDE OF ANY AFTERNOON CONVECTION. PREV DISCUSSION... /ISSUED 256 AM EDT MON AUG 25 2014/ SHORT TERM (TODAY-WEDNESDAY)... IT CONTINUES TO LOOK MORE FAVORABLE THAT T.S. CRISTOBAL WILL MOVE NORTH AND NORTHEAST AWAY FROM SOUTH FLORIDA. SO THE PRIMARY IMPACTS WILL BE AN INCREASE IN RIP CURRENTS AT THE ATLANTIC BEACHES AND BUILDING SEAS IN THE ATLANTIC FOR MARINE INTERESTS AS A SMALL NORTHEAST SWELL IS GENERATED. MODELS SUGGEST A MOISTURE SURGE MOVING INTO THE REGION AFTER 12Z THIS MORNING WHICH IS A RESULT IN THE NORTHEAST CIRCULATION DEVELOPING WITH CRISTOBAL. THE CURRENT PWAT IS AROUND 1.75 INCHES WITH FORECAST SOUNDINGS SHOWING AN INCREASE TO 2+ INCHES THIS MORNING. THE STEERING FLOW WILL BE NORTHEAST TO SOUTHWEST SO THE EAST COAST COULD GET A QUICK PASSING SHRA/TSRA WITH THE GREATEST ACTIVITY BEING OVER THE INTERIOR AND SOUTHWEST COAST. THE HRRR IS SHOWING SOMETHING VERY SIMILAR WITH SCATTERED SHOWERS NEAR THE EAST COAST WITH A FLARE UP INLAND AROUND THE LAKE AFTER 17Z. MUCH DRIER AIR ALOFT WILL THEN MOVE INTO SOUTH FLORIDA ON TUESDAY WITH FORECAST SOUNDINGS SHOWING PWAT DROPPING TO LESS THAN 1.25 INCHES WITH THE NORTHEAST STEERING FLOW CONTINUING SO ONLY ISOLATED OR LOW END SCATTERED IS EXPECTED ACROSS THE INTERIOR AND SOUTHWEST COAST TUESDAY AFTERNOON/EVENING. THEY DRYING TREND WILL PERSIST INTO WEDNESDAY ALTHOUGH FORECAST SOUNDINGS DO SHOW A SLIGHT RETURN OF MOISTURE WITH PWAT CLIMBING BACK TO OVER 1.5 INCHES BY LATE IN THE DAY. STILL, NOT MUCH COVERAGE IS ANTICIPATED WITH A MORE SOUTHEAST STEERING FLOW PATTERN RETURNING SO STORMS WOULD TEND TO FORM INLAND FROM THE EAST COAST AND BE CONCENTRATED OVER THE INTERIOR ONLY. LONG TERM (THURSDAY-SUNDAY)... AS CRISTOBAL EXITS TO THE NORTHEAST, A DEEP LAYER RIDGE WILL BUILD BACK TO THE NORTH LATE THIS WEEK INTO THE UPCOMING WEEKEND WITH AN INCREASE IN MOISTURE AND PWATS RETURNING TO NEAR NORMAL VALUES. THIS WOULD CONTINUE TO STEER THE STORMS AWAY FROM THE EAST COAST TO THE INTERIOR AND WEST COAST REGIONS. NO OTHER TROPICAL SYSTEMS ARE EXPECTED TO AFFECT SOUTH FLORIDA THROUGH THE EXTENDED PERIOD. MARINE... NORTHEAST WINDS WILL PREVAIL THROUGH MIDWEEK, STRENGTHENING A TAD TODAY AND TUESDAY AS THE PRESSURE GRADIENT TIGHTENS. THIS WILL LEAD TO INCREASING SEAS ESPECIALLY IN THE GULF STREAM OFF THE PALM BEACH COAST...WHERE HAZARDOUS SEAS OF 7+ FT ARE POSSIBLE DUE TO FLOW COUNTERACTING THE GULF STREAM CURRENT ALONG WITH AN INCOMING SMALL NORTHEAST SWELL. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 91 80 91 79 / 40 20 10 10 FORT LAUDERDALE 91 81 92 81 / 40 20 10 10 MIAMI 89 80 91 79 / 60 20 10 10 NAPLES 92 78 93 77 / 60 30 20 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS MIAMI FL
749 AM EDT MON AUG 25 2014 .AVIATION... SURFACE FLOW SHOULD REMAIN NORTHERLY THROUGH THE MORNING TO NORTHEAST BY THE AFTERNOON. A SURGE OF ASSOCIATED MOISTURE WILL KEEP ISOLATED TO SCATTERED SHOWERS PUSHING SOUTH ACROSS THE ATLANTIC WATERS THROUGH THE MORNING. A FEW OF THESE SHOWERS MAY MAKE IT INTO KFXE SOUTHWARD. THEREFORE KEPT VCSH AT THESE TERMINALS THROUGH THE REMAINDER OF THE MORNING. OTHERWISE...VFR CONDITIONS ARE EXPECTED OUTSIDE OF ANY AFTERNOON CONVECTION. && .PREV DISCUSSION... /ISSUED 256 AM EDT MON AUG 25 2014/ SHORT TERM (TODAY-WEDNESDAY)... IT CONTINUES TO LOOK MORE FAVORABLE THAT T.S. CRISTOBAL WILL MOVE NORTH AND NORTHEAST AWAY FROM SOUTH FLORIDA. SO THE PRIMARY IMPACTS WILL BE AN INCREASE IN RIP CURRENTS AT THE ATLANTIC BEACHES AND BUILDING SEAS IN THE ATLANTIC FOR MARINE INTERESTS AS A SMALL NORTHEAST SWELL IS GENERATED. MODELS SUGGEST A MOISTURE SURGE MOVING INTO THE REGION AFTER 12Z THIS MORNING WHICH IS A RESULT IN THE NORTHEAST CIRCULATION DEVELOPING WITH CRISTOBAL. THE CURRENT PWAT IS AROUND 1.75 INCHES WITH FORECAST SOUNDINGS SHOWING AN INCREASE TO 2+ INCHES THIS MORNING. THE STEERING FLOW WILL BE NORTHEAST TO SOUTHWEST SO THE EAST COAST COULD GET A QUICK PASSING SHRA/TSRA WITH THE GREATEST ACTIVITY BEING OVER THE INTERIOR AND SOUTHWEST COAST. THE HRRR IS SHOWING SOMETHING VERY SIMILAR WITH SCATTERED SHOWERS NEAR THE EAST COAST WITH A FLARE UP INLAND AROUND THE LAKE AFTER 17Z. MUCH DRIER AIR ALOFT WILL THEN MOVE INTO SOUTH FLORIDA ON TUESDAY WITH FORECAST SOUNDINGS SHOWING PWAT DROPPING TO LESS THAN 1.25 INCHES WITH THE NORTHEAST STEERING FLOW CONTINUING SO ONLY ISOLATED OR LOW END SCATTERED IS EXPECTED ACROSS THE INTERIOR AND SOUTHWEST COAST TUESDAY AFTERNOON/EVENING. THEY DRYING TREND WILL PERSIST INTO WEDNESDAY ALTHOUGH FORECAST SOUNDINGS DO SHOW A SLIGHT RETURN OF MOISTURE WITH PWAT CLIMBING BACK TO OVER 1.5 INCHES BY LATE IN THE DAY. STILL, NOT MUCH COVERAGE IS ANTICIPATED WITH A MORE SOUTHEAST STEERING FLOW PATTERN RETURNING SO STORMS WOULD TEND TO FORM INLAND FROM THE EAST COAST AND BE CONCENTRATED OVER THE INTERIOR ONLY. LONG TERM (THURSDAY-SUNDAY)... AS CRISTOBAL EXITS TO THE NORTHEAST, A DEEP LAYER RIDGE WILL BUILD BACK TO THE NORTH LATE THIS WEEK INTO THE UPCOMING WEEKEND WITH AN INCREASE IN MOISTURE AND PWATS RETURNING TO NEAR NORMAL VALUES. THIS WOULD CONTINUE TO STEER THE STORMS AWAY FROM THE EAST COAST TO THE INTERIOR AND WEST COAST REGIONS. NO OTHER TROPICAL SYSTEMS ARE EXPECTED TO AFFECT SOUTH FLORIDA THROUGH THE EXTENDED PERIOD. MARINE... NORTHEAST WINDS WILL PREVAIL THROUGH MIDWEEK, STRENGTHENING A TAD TODAY AND TUESDAY AS THE PRESSURE GRADIENT TIGHTENS. THIS WILL LEAD TO INCREASING SEAS ESPECIALLY IN THE GULF STREAM OFF THE PALM BEACH COAST...WHERE HAZARDOUS SEAS OF 7+ FT ARE POSSIBLE DUE TO FLOW COUNTERACTING THE GULF STREAM CURRENT ALONG WITH AN INCOMING SMALL NORTHEAST SWELL. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 91 80 91 79 / 40 20 10 10 FORT LAUDERDALE 91 81 92 81 / 40 20 10 10 MIAMI 89 80 91 79 / 60 20 10 10 NAPLES 92 78 93 77 / 60 30 20 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1135 AM EDT MON AUG 25 2014 .SYNOPSIS... HIGH PRESSURE RIDGING INTO THE FORECAST AREA FROM THE NORTH WILL DIRECT DRY AIR INTO THE AREA THROUGH MIDWEEK. TEMPERATURES WILL BE NEAR NORMAL EARLY THIS WEEK THEN A WARMING TREND WILL DEVELOP FOR MID-WEEK. && .NEAR TERM /THROUGH TONIGHT/... A LARGE UPPER LEVEL RIDGE EXTENDED FROM THE SOUTHERN PLAINS TO NEW ENGLAND WITH AN UPPER TROUGH WELL OFF THE EAST COAST. SURFACE HIGH PRESSURE STRETCHED FROM THE NORTHEASTERN STATES ACROSS THE CAROLINAS AND GEORGIA. WEAK COLD/DRY ADVECTION THIS AFTERNOON WITH PWAT BELOW ONE INCH. SURFACE PRESSURE GRADIENT MODERATELY TIGHT SO EXPECT SOME GUSTY NORTHEAST WINDS THIS AFTERNOON. TEMPERATURES WILL BE SEASONABLE WITH HIGHS IN THE RANGING THROUGH THE 80S UNDER SUNNY SKIES. MOIST ONSHORE LOW COULD BRING AN AREA OF CLOUDS ACROSS THE AREA OVERNIGHT. BOTH THE RUC AND NAM INDICATE PWAT INCREASING TO NEAR 2.00 INCHES WITH AN INCREASE IN 8H50 MOISTURE. KEPT OVERNIGHT LOWS IN LINE WITH GUIDANCE...RANGING THROUGH THE 60S. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... HIGH PRESSURE DOMINATES THROUGH THE PERIOD. AIR MASS REMAINS DRY. UPPER RIDGE BUILDING EAST THROUGH THE PERIOD SO WARMING TREND DEVELOPING. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... HIGH PRESSURE WILL REMAIN OVER THE AREA FOR MUCH OF THE WEEK. LATEST MODELS SUGGEST FRONT REMAINING NORTH OF THE REGION FRIDAY AND RIDGE OVER THE AREA SO BACKED OFF ON POPS. ANOTHER COLD FRONT MOVING IN FROM THE WEST SUNDAY. FORECASTED LOW CHANCE POPS FRIDAY THROUGH SUNDAY. TEMPERATURES NEAR OR JUST SLIGHTLY BELOW NORMAL MONDAY THROUGH WEDNESDAY...AND A LITTLE ABOVE NORMAL FOR THE REMAINDER OF THE EXTENDED PERIOD. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... VFR CONDITIONS EXPECTED TO CONTINUE THROUGH THE 24 HOUR TAF PERIOD. DRY HIGH PRESSURE BUILDING DOWN THE EASTERN SEABOARD...COUPLED WITH AN UPPER RIDGE OVERHEAD...WILL ENSURE FAIR AND DRY WEATHER. WINDS WILL BE NORTHEAST AROUND 10 KNOTS WITH GUST NEAR 20 KNOTS THIS AFTERNOON. EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION EXPECTED. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
647 AM CDT MON AUG 25 2014 .UPDATE... ISSUED AT 645 AM CDT MON AUG 25 2014 HAVE UPDATED THE FORECAST TO ADD EARLY MORNING FOG AND LOW CLOUDS OVER THE FAR EAST...WHERE SURFACE REPORTS AND SATELLITE FOG CHANNEL SHOWED THE EDGE OF A LARGER DECK OVER NE IL EDGING INTO THE NW IL COUNTIES AND OCCASIONALLY LOWERING VISIBILITIES TO LESS THAN 1 MILE. ELSEWHERE...THUNDERSTORMS CONTINUE TO TRAIN IN A SW TO NE FASHION...PARALLEL TO THE UPPER LEVEL FLOW FROM CENTRAL IA INTO SW WI. SO FAR...THE STORMS HAVE REMAINED MAINLY NW OF A LINE FROM BELLE PLAINE THROUGH CENTRAL CITY TO DUBUQUE. RADAR ESTIMATES INDICATE RAINFALL AMOUNTS OF A QUARTER INCH TO NEARLY 1.5 INCHES HAS FALLEN OVER THE PAST SEVERAL HOURS IN THIS AREA. CELLS SHOULD CONTINUE TO TRAIN ALONG THIS AXIS...AND POSSIBLY SHIFT A BIT TO THE SOUTHEAST BEFORE DISSIPATING WITH THE LOSS OF UPPER LEVEL SUPPORT AND THE DIURNAL WANING OF THE LOW LEVEL JET THIS MORNING. EVEN WITH A POSSIBLE ADDITIONAL 1 INCH OF RAIN...NOT ANTICIPATING ANY SIGNIFICANT HYDRO ISSUES AS FLASH FLOOD GUIDANCE VALUES ARE MAINLY OVER 3 INCHES PER 3 HOURS IN THIS AREA DUE TO THE RECENT DRY WEATHER. && .SYNOPSIS... ISSUED AT 334 AM CDT MON AUG 25 2014 THUNDERSTORMS HAVE DEVELOPED EARLY THIS MORNING ALONG AND AHEAD OF THE SURFACE FRONT EXTENDING ROUGHLY FROM WESTERN LAKE SUPERIOR SW ACROSS WESTERN WI...SW MN...INTO W CENTRAL IA. THIS WAS ALONG AN AXIS OF HIGH THETAE INDICATED BY 850 MB DEWPOINTS OF 14 TO 16 C FROM NORTHEAST KS INTO SW ONTARIO AT 00Z...WITH CONVERGENCE ASSISTED BY 35KT TO 40 KT SW WINDS AT 850 MB. THIS MOISTURE WAS BEING PULLED NORTHWARD BY A STRONG SURFACE AND UPPER LEVEL LOW SEEN ON WV IMAGERY ALONG THE ND/MANITOBA BORDER. AT 3 AM...THE LEADING LINE OF SCATTERED THUNDERSTORMS WAS MOVING INTO BUCHANAN AND BENTON COUNTIES...INTO A VERY HUMID AIRMASS WITH DEWPOINTS IN THE LOWER TO MID 70S AND AIR TEMPERATURES IN THE MID TO UPPER 70S. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 334 AM CDT MON AUG 25 2014 FORECAST CHALLENGES CENTER ON THUNDERSTORMS THIS MORNING AND AGAIN TONIGHT...AND HEAT HEADLINES TODAY AS THE HOT AND HUMID CONDITIONS PERSIST OVER THE REGION. IN THE NEAR TERM...A SEMI-LINEAR MCS WILL LIKELY MOVE ACROSS THE FORECAST AREA MAINLY NORTH OF I-80...DRIVEN BY A WEAK SHORTWAVE FLOW IN THE NW FLOW ALOFT. WHILE NO INDIVIDUAL FORECAST MODEL HAS HAD A GOOD HANDLE ON TRENDS OVERNIGHT...THE HIGH RES WRF AND RAP MODELS APPEAR TO HAVE THE BEST HANDLE ON THE CONVECTION ENTERING THE NORTH. THESE HAVE THE THUNDERSTORMS ADVANCING THROUGH THE NORTH OVER THE NEXT SEVERAL HOURS AND THEN DISSIPATING BY NOON...AND HAVE TRENDED THE FORECAST ACCORDINGLY. THE LATEST RAP IS ALONE WITH DEVELOPING THUNDERSTORMS IN THE HIGH MUCAPE AXIS FURTHER SE...OVER 4000 J/KG...OVER W CENTRAL IL TOWARD SUNRISE...WHICH WHILE NOT IN THE CURRENT FORECAST CANNOT BE ENTIRELY RULED AND WILL WATCH TRENDS CLOSELY. OTHERWISE...THIS SHOULD BE FOLLOWED BY CLEARING SKIES AND A RETURN TO THE HEAT AND HUMIDITY SEEN OVER THE AREA YESTERDAY. DUE TO UNCERTAINTIES IN THE TIMING OF THE DISSIPATING MCS IN THE NORTH AND POSSIBLE DEBRIS CLOUDS FROM STORMS IN THE PLAINS...ALONG WITH 850 MB TEMPERATURES PROGGED ABOUT 1 DEGREE COOLER...HAVE TRENDED HIGHS A DEGREE OR TWO COOLER THAN SUNDAY...WITH UPPER 80S NW TO LOWER 90S CENTRAL AND SOUTH. DEWPOINTS WILL HOLD IN THE LOWER TO MID 70S AND POSSIBLY TOUCH THE UPPER 70S AT TIMES LATE IN THE DAY. THIS COMBINATION WILL SEND HEAT INDEX VALUES TO JUST ABOVE 100 ACROSS THE SOUTH AND WILL KEEP THE PREVIOUS HEAT ADVISORY CONFIGURATION IN PLACE. TONIGHT...THE SETUP WILL BE FAVORABLE FOR ANOTHER MCS AS THE SURFACE FRONT SLOWLY ADVANCES THROUGH THE FORECAST AREA AND MODEST CONVERGENCE OCCURS IN THE 850 MB THETAE AXIS AS IT SHIFTS OVERHEAD. HAVE KEPT LIKELY POPS IN THE NORTH WITH SLIGHT TO LOW END CHANCE POPS IN THE SOUTH TOWARD MORNING. THE MAIN THREAT WILL BE LOCALLY HEAVY RAINFALL. IT WILL BE ANOTHER WARM AND VERY HUMID NIGHT WITH TEMPERATURES AND DEWPOINTS IN THE 70S...EXCEPT IN THE FAR NW...WHERE THE CURRENT FRONTAL TIMING SUGGESTS READINGS LOWERING INTO THE UPPER 60S. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 334 AM CDT MON AUG 25 2014 AN ORGANIZED THUNDERSTORM COMPLEX SHOULD MOVE INTO THE AREA TUESDAY MORNING AND DISSIPATE DURING THE MORNING. BOUNDARIES LEFT OVER FROM THIS COMPLEX COMBINED WITH A WEAK FRONT MOVING THROUGH THE AREA WILL PROVIDE THE FOCUS FOR NEW CONVECTION TUESDAY AFTERNOON AND EVENING. HIGH MOISTURE LEVELS IN THE LOWER ATMOSPHERE MEANS ANY STORM WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL. CLOUD COVER AND RAIN WILL PLAY INTO HOW WARM IT WILL GET ON TUESDAY. THE SOUTHEAST HALF MAY SEE TEMPERATURES AROUND 90 WITH HEAT INDEX READINGS IN THE UPPER 90S TO JUST OVER 100. ANOTHER THUNDERSTORM COMPLEX IS EXPECTED TO DEVELOP IN WESTERN IOWA TUESDAY EVENING AND THEN MOVE MAINLY EAST OVERNIGHT INTO WEDNESDAY MORNING. THIS STORM COMPLEX SHOULD ARRIVE IN THE WESTERN THIRD OF THE CWFA IN THE PRE-DAWN HOURS AND SLOWLY DISSIPATE ACROSS THE AREA WEDNESDAY MORNING. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE FROM THE STORMS DUE TO HIGH MOISTURE LEVELS. LIKE TUESDAY...BOUNDARIES LEFT OVER FROM THE WEDNESDAY STORM COMPLEX WILL PROVIDE THE FOCUS FOR NEW CONVECTION WEDNESDAY AFTERNOON AND EVENING. SIGNALS FROM THE MODELS SUGGEST YET ANOTHER THUNDERSTORM COMPLEX WILL DEVELOP IN WESTERN IOWA WEDNESDAY EVENING AND MOVE GENERALLY EAST OVERNIGHT AND ARRIVE IN THE WESTERN THIRD OF THE AREA IN THE PRE-DAWN HOURS. LOCALLY HEAVY RAINFALL MAY BE POSSIBLE FROM SOME OF THE STRONGER STORMS. THURSDAY ON... THE MODEL CONSENSUS HAS CHANCE POPS IN EACH 12 HOUR PERIOD FROM THURSDAY THROUGH SATURDAY NIGHT. TEMPERATURES SHOULD BE NEAR NORMAL. ON SUNDAY...THE MODEL CONSENSUS HAS SLIGHT CHANCE TO LOW CHANCE POPS. THE LARGE SCALE PICTURE SUGGESTS THE WEATHER PATTERN WILL REMAIN FAIRLY ACTIVE WITH A FRONT STALLED OUT JUST SOUTH OF THE AREA. IT WILL NOT RAIN CONTINUOUSLY THE ENTIRE TIME. THERE WILL BE PERIODS OF DRY WEATHER THAT MAY LAST 6 OR 12 HOURS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 645 AM CDT MON AUG 25 2014 A SLOW MOVING AXIS OF THUNDERSTORMS OVER NORTHEAST IOWA MAY BRIEFLY IMPACT THE CID AND DBQ TERMINALS EARLY THIS MORNING. FOG AND A FEW AREAS OF LOW CLOUDS WILL IMPACT MOST OF THE TERMINALS WITH PERIODS OF MVFR CONDITIONS UNTIL MID MORNING. OTHERWISE...TODAY WILL BE MAINLY VFR WITH VERY HUMID CONDITIONS. ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED TO MOVE THROUGH EASTERN IOWA AND NORTHWEST ILLINOIS LATE TONIGHT AS A COOL FRONT SLOWLY DROPS SOUTH THROUGH THE AREA. THIS IS MOST LIKELY TO AFFECT THE CID...DBQ AND MLI TERMINALS...WHERE PROB30 GROUPS COVER THE POTENTIAL FOR NOW. ALSO...LIGHT WINDS AND LINGERING LOW LEVEL MOISTURE WILL ALSO LEAD TO MVFR FOG...WHICH IS ALSO INCLUDED FOR THE LATE NIGHT AND EARLY MORNING PERIODS. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...HEAT ADVISORY FROM NOON TODAY TO 8 PM CDT THIS EVENING FOR LOUISA-MUSCATINE-SCOTT. HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR DES MOINES-HENRY IA-LEE-VAN BUREN. IL...HEAT ADVISORY FROM NOON TODAY TO 8 PM CDT THIS EVENING FOR BUREAU-HENRY IL-MERCER-PUTNAM-ROCK ISLAND-WHITESIDE. HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR HANCOCK-HENDERSON- MCDONOUGH-WARREN. MO...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR CLARK-SCOTLAND. && $$ UPDATE...SHEETS SYNOPSIS...SHEETS SHORT TERM...SHEETS LONG TERM...08 AVIATION...SHEETS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
745 AM EDT MON AUG 25 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 535 AM EDT MON AUG 25 2014 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A VIGOROUS LOOKING SHORTWAVE LIFTING THRU ND INTO MANITOBA. ASSOCIATED SFC LOW WAS MOVING INTO SE MANITOBA WITH COLD FRONT EXTENDING THRU FAR ERN MN. AS EXPECTED...SCT TSTMS DEVELOPED AHEAD OF FRONT IN MN LATE YESTERDAY AFTN/EVENING. STORMS THEN ORGANIZED INTO A LINE AND PUSHED E INTO WI/UPPER MI. AS OF 09Z...SHRA/TSTMS EXTENDED FROM NCNTRL LAKE SUPERIOR TO THE HURON MTNS AND CRYSTAL FALLS. CONVECTION HAS HELD TOGETHER FOR MUCH OF THE NIGHT...AND IT HAS ONLY BEEN IN THE LAST HR OR TWO THAT A NOTABLE DIMINISHING TREND HAS BEGUN. NSSL WRF RUN FROM 00Z/24 AUG DID A GREAT JOB AND BETTER THAN ANY OTHER MODEL IN CAPTURING WHAT OCCURRED LAST NIGHT INTO EARLY THIS MORNING... INCLUDING THE DIMINISHING TREND NOW UNDERWAY. WHILE THERE IS STILL SOME INCREASE IN INSTABILITY AHEAD OF CONVECTION PER SPC MESOANALYSIS OF 3HR ML/MUCAPE CHANGE...OVERALL MAGNITUDE OF INSTABILITY IS NOTABLY LESS THAN WHAT WAS SUPPORTING THE CONVECTION EARLIER IN THE NIGHT. DIMINISHING INSTABILITY COMBINED WITH WEAKENING LOW-LEVEL JET WILL CONTINUE TO CAUSE SHRA/TSRA TO WEAKEN AS THEY PUSH E THIS MORNING. QUESTION THEN BECOMES WHETHER THERE WILL BE REDEVELOPMENT ALONG THE MOISTURE AXIS THAT WILL BE SLOWING DOWN. NSSL WRF INCLUDING THE NCEP ARW/NMM WHICH ALSO DID WELL WITH CONVECTION LAST NIGHT SUGGEST LITTLE OR NO ADDITIONAL DEVELOPMENT THIS AFTN. WILL BASICALLY FOLLOW THAT SCENARIO GIVEN A LACK OF MUCH FORCING THIS AFTN. WITH INCREASING SUNSHINE AND 850MB THERMAL RIDGE OVER THE AREA...TODAY SHOULD BE THE WARMEST DAY OF THE WEEK. FCST SOUNDINGS SUPPORT MAX TEMPS AS HIGH AS THE MID/UPPER 80S OVER ROUGHLY THE W HALF. COULD BE WARMER DEPENDING ON HOW QUICKLY CLOUDS SCATTER OUT. E WILL BE COOLER WITH MORE CLOUD COVER AND CONTINUED SOUTHERLY FLOW OFF LAKE MICHIGAN. LOOKS LIKE A SECONDARY COLD FRONT/TROF WILL SWEEP ACROSS THE AREA LATER THIS AFTN/EVENING. AS THE TROF MOVES INTO THE ERN FCST AREA THIS EVENING WHERE MOISTURE/INSTABILITY LINGER...ISOLD SHRA AND PERHAPS A TSRA MAY DEVELOP FROM ERN LAKE SUPERIOR INTO ERN UPPER MI. OTHERWISE...EXPECT A DRY NIGHT...BECOMING COOLER AND LESS HUMID. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 403 AM EDT MON AUG 25 2014 A FAIRLY QUIET AND GENERALLY DRY LONG TERM PERIOD IS IN STORE FOR THE UPPER GREAT LAKES REGION FOR TUESDAY THROUGH THE WEEKEND. THIS TRANSITION WILL OCCUR AS A RESULT OF THE LOW PRESSURE SYSTEM MOVING THROUGH NORTHERN ONTARIO TODAY AND THE ASSOCIATED COLD FRONT THAT PASSES THROUGH. BEHIND THIS LOW AND ASSOCIATED SHORTWAVE...HIGH PRESSURE FROM THE EASTERN DAKOTAS WILL SHIFT EAST OVER THE UPPER GREAT LAKES REGION BY WEDNESDAY WHILE A WEAK UPPER TROUGH SWEEPS THROUGH. IN GENERAL...EXPECT THIS HIGH PRESSURE RIDGE TO SUPPRESS ANY PRECIPITATION TO THE SOUTH OF THE AREA THROUGH THURSDAY. THERE ARE A COUPLE MINOR ITEMS TO NOTE. FIRST...THE SECONDARY SHORTWAVE MOVING THROUGH THE FLOW LATE TUESDAY NIGHT INTO WEDNESDAY MORNING COULD TRY TO SPARK AN ISOLATED SHOWER BUT FEEL THE DRY AIR IN THE LOWER LEVELS ASSOCIATED WITH THE HIGH PRESSURE RIDGE WILL INHIBIT ANY RAIN FROM REACHING THE SURFACE. THUS...WILL JUST SHOW PASSING MID CLOUDS AS THAT WAVE MOVES THROUGH. THE OTHER ITEM IS THE MUCH COOLER AIR BELOW 850MB THAT WILL BE SURGING INTO THE CWA LATE TONIGHT INTO TUESDAY. THIS WILL SETUP A RETURN TO ANOTHER COOLER PERIOD OF HIGH TEMPERATURES OVER THE CWA. WITH THE COLD AIR JUST STARTING TO MOVE IN ON TUESDAY...HIGHS OVER THE CENTRAL/EAST WILL STILL RISE INTO THE UPPER 60S AND LOWER 70S WHILE AREAS OVER THE WEST NEAR LAKE SUPERIOR WILL STAY IN THE MID 60S WITH THE GUSTY WESTERLY WIND OFF THE LAKE. WEDNESDAY WILL BE THE COOLEST DAY (AIDED BY THE MORNING MID CLOUDS LIMITING HEATING AND MODEL AVERAGE 850MB TEMPS AROUND 6-7C)...WITH HIGHS IN THE 60S OVER MOST OF THE CWA. 850MB TEMPS WILL REBOUND SLIGHTLY ON THURSDAY AND ALLOW HIGHS TO BE IN THE UPPER 60S TO AROUND 70 DEGREES. ALONG WITH THAT COOLER AIR ON TUESDAY MORNING...SOME OF THE MODELS ARE INDICATING ENOUGH MOISTURE FOR SOME CLOUDS OVER THE NORTH HALF OF THE CWA. THINK THE COVERAGE WILL BE THE GREATEST DURING THE AFTERNOON HOURS WHEN THE DIURNAL HEATING IS MAXIMIZED AND WILL SHOW PARTLY CLOUDY SKIES DURING THAT TIME. EXPECT MOSTLY CLEAR SKIES FOR THE REST OF THE MIDDLE OF THE WORK WEEK. THE FOCUS THURSDAY NIGHT INTO THE WEEKEND WILL BE THE UPPER DISTURBANCE MOVING OUT OF THE CENTRAL ROCKIES AND INTO THE CENTRAL PLAINS ON WEDNESDAY. THE INITIAL PORTION OF THIS WAVE WILL SHIFT NORTHEAST TOWARDS THE UPPER GREAT LAKES REGION THURSDAY NIGHT AND FRIDAY...WITH MODELS STILL VARYING ON THE NORTHWARD EXTENT OF THE WAVE AND ASSOCIATED PRECIP. CURRENT CONSENSUS IS FOR IT TO BRUSH THE SOUTHEAST THIRD OF THE CWA AND WILL SHOW SLIGHT CHANCES IN THAT AREA. THE SECOND WAVE WILL PUSH THROUGH THE AREA FRIDAY NIGHT INTO SATURDAY AND BRING ANOTHER OPPORTUNITY FOR PRECIPITATION. MODELS ALSO VARYING ON THE LOCATION THIS WAVE...SO WILL FOLLOW A BLEND OF GEM/GFS/ECMWF FOR POPS (SLIGHT OR LOW END CHANCES) WITH THE BEST CHANCES OVER THE SOUTHEAST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 745 AM EDT MON AUG 25 2014 AREA OF SHRA HAS MOVED E OF KIWD/KCMX. BEHIND THE SHRA...KIWD SHOULD CONTINUE TO SEE VFR CONDITIONS. AT KCMX...IFR CIGS HAVE RECENTLY ARRIVED. EXPECT THIS TO BE SHORT LIVED WITH A RETURN TO VFR BY MID OR LATE MORNING. VFR CONDITIONS WILL THEN CONTINUE AT KIWD/KCMX FOR THE REMAINDER OF THE FCST PERIOD AS DRIER AIR FLOWS INTO THE AREA BEHIND A COLD FRONT. AT KSAW...-SHRA WILL END IN THE NEXT FEW HRS. BASED ON OBS AROUND THE AREA...VFR CONDITONS WILL LIKELY PREVAIL... BUT THERE MAY BE OCNL MVFR CIGS. VFR CONDITIONS WILL THEN BE THE RULE FOR REMAINDER OF THE FCST PERIOD. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 535 AM EDT MON AUG 25 2014 FOG MAY BE AN ISSUE OVER PORTIONS OF LAKE SUPERIOR THRU THIS EVENING...MAINLY CNTRL/E AND ESPECIALLY NE GIVEN THE HUMID AIR MASS AND PCPN THAT HAS OCCURRED. PASSAGE OF COLD FRONT AND ARRIVAL OF DRIER AIR TODAY/THIS EVENING WILL THEN WORK TO CLEAR OUT THE FOG FROM W TO E. BEHIND FRONT...WESTERLY WINDS WILL INCREASE TO 15-25KT OVER WRN LAKE SUPERIOR THIS AFTN AND THEN OVER CNTRL LAKE SUPERIOR THIS EVENING. THESE STRONGER WINDS WILL LINGER INTO TUE MORNING...THEN WINDS WILL DIMINISH AS HIGH PRES MOVES CLOSER TO THE AREA. THE HIGH WILL SETTLE INTO THE UPPER LAKES TUE NIGHT THRU THU...BRINGING A PERIOD OF LIGHTER WINDS MOSTLY UNDER 15KT. THE LIGHTER WINDS WILL LINGER INTO FRI DESPITE THE HIGH MOVING TO THE E. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...SRF AVIATION...ROLFSON MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED
NWS MORRISTOWN TN
1002 AM EDT MON AUG 25 2014 .DISCUSSION... A BROAD UPPER-LEVEL HIGH PRESSURE RIDGE WILL CONTINUE TO BUILD INTO THE TENNESSEE VALLEY TODAY...AND BECOME THE DOMINANT WEATHER FEATURE ACROSS THE AREA FOR THE NEXT SEVERAL DAYS. HOWEVER FOR TODAY...MOISTURE STILL PRESENT UNDERNEATH THIS RIDGE HAS RESULTED IN SCATTERED TO LOCALLY DENSE CLOUD COVER THIS MORNING /ALONG WITH A COUPLE OF ROGUE SHOWERS OVER THE PLATEAU/. AS DRY AIR BEGINS TO WORK ITS WAY INTO THE REGION...THIS CLOUD COVER WILL GRADUALLY BREAK UP AND SHIFT OFF TO THE WEST...RESULTING IN A MOSTLY TO PARTLY SUNNY DAY ACROSS THE REGION. GIVEN THE STRONGER CAP DEVELOPING ALOFT...AM NOT EXPECTING MUCH IN THE WAY OF CONVECTION THIS AFTERNOON. BUT...THE HRRR IN PARTICULAR DOES HINT AT SOME ISOLATED SHOWERS/STORMS DEVELOPING AFTER 18Z ALONG THE PLATEAU... SO HAVE ADDED A SOME LOW-END MENTIONABLE POPS IN THIS AREA THIS AFTERNOON. HIGHS WILL BE SLIGHTLY COOLER TODAY WITH THE CLOUD COVER...BUT WILL STILL REACH THE MID TO UPPER 80S TODAY. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 88 67 91 66 / 20 0 0 10 KNOXVILLE MCGHEE TYSON AIRPORT, TN 87 65 88 64 / 10 0 0 10 OAK RIDGE, TN 87 66 89 64 / 10 0 0 10 TRI CITIES AIRPORT, TN 86 56 86 61 / 10 0 10 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ AMP
AREA FORECAST DISCUSSION
NWS PUEBLO CO
426 PM MDT MON AUG 25 2014 .UPDATE... ISSUED AT 424 PM MDT MON AUG 25 2014 UPDATED FOR INCLUSION OF SVR TSTORM WATCH FOR EL PASO CROWLEY AND KIOWA COUNTIES. ROSE && .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 305 PM MDT MON AUG 25 2014 CURRENTLY...COLD FRONT HAS BECOME STATIONARY NEAR THE NM BORDER THIS AFTERNOON...AND WILL LIKELY DRIFT BACK NORTHWARD TOWARD THE ARKANSAS RIVER BY 00Z. CONVECTION OVER THE MOUNTAINS AND ALONG THE RATON MESA HAS BEEN RELATIVELY WEAK SO FAR AS STORMS HAVE YET TO TAP DEEPER INSTABILITY NEAR THE KS BORDER AND FARTHER NORTH NEAR THE PALMER DIVIDE. WITH COOL AIR SLIGHTLY DEEPER THAN EXPECTED...APPEARS HIGH TEMPS WILL END UP JUST SHY OF FORECAST READINGS. TONIGHT...MESOSCALE MODELS CONTINUE TO POINT TO AREAS ALONG AND NORTH OF THE PALMER DIVIDE HAVING THE BEST CHANCE FOR STRONG/SEVERE CONVECTION...THOUGH LATEST HRRR HINTS AT SOME SOME BRIEF STRONGER STORMS OVER THE FAR EASTERN PLAINS...AS FRONTAL BOUNDARY RETREATING NORTHWARD PROVIDES SOME ENHANCED CONVERGENCE. WEAK SHORT WAVE...OVER WRN CO CURRENTLY...WILL ALSO PROVIDE SOME UPWARD MOTION AS IT CROSSES THE AREA THIS EVENING. BY MIDNIGHT...SUSPECT CONVECTION WILL SHIFT NORTHEAST AND COALESCE INTO AN MCS OVER NWRN KS/SRN NEB...WITH FAIRLY LARGE COLD POOL GIVING SURFACE FRONT A RENEWED SHOVE SOUTHWARD THROUGH THE EASTERN PLAINS. WITH A GRADUAL INCREASE IN MID LEVEL MOISTURE THROUGH THE NIGHT AND BOUNDARY MOVING BACK SOUTHWARD...WILL ONLY GRADUALLY TAPER OFF POPS THROUGH THE EVENING...WITH AT LEAST SOME ISOLATED TSRA POSSIBLE PAST MIDNIGHT. TUESDAY.. UPPER LOW WILL CONTINUE TO SLOWLY PUSH EASTWARD THROUGH THE GREAT BASIN...WITH STRENGTHENING S-SW FLOW AHEAD OF THE SYSTEM PUSHING AN INCREASING AMOUNT OF TROPICAL MOISTURE NORTHWARD INTO COLORADO. SURFACE FRONT WILL LIKELY STAY SOUTH OF THE ARKANSAS RIVER THROUGH THE DAY...WITH E-SE FLOW PUSHING 55F-60F DEWPOINTS WESTWARD TOWARD THE I-25 CORRIDOR. WITH MOISTURE PLENTIFUL...EXPECT EARLY INITIATION OF CONVECTION WITH STORMS FIRING OVER THE MOUNTAINS BEFORE 18Z AND SPREADING QUICKLY TO LOWER ELEVATIONS BY 21Z. MAIN THREAT TOMORROW OVER ALL AREAS WILL BE HEAVY RAINFALL...THOUGH WITH CAPES OVER 1000 J/KG AND 0-6KM SHEAR OF 30-40 KTS...A SEVERE STORM OR TWO IS POSSIBLE ON THE PLAINS MAINLY ALONG AND NORTH OF THE ARKANSAS RIVER. ALL IN ALL...IT LOOKS LIKE A VERY WET DAY OVER MUCH OF SOUTHERN COLORADO...AND WITH CLOUDS AND PRECIP FAIRLY QUICK TO DEVELOP...MAX TEMPS SHOULD COOL AT LEAST A FEW DEGF VERSUS MON READINGS. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 305 PM MDT MON AUG 25 2014 TUESDAY NIGHT THROUGH FRIDAY...LATEST RUNS OF THE NAM...GFS AND EC MODELS ARE IN FAIRLY GOOD AGREEMENT ON THE PROGRESSION OF THE UPPER TROUGH ACROSS THE REGION THROUGH THIS WEEK. TUE EVENING THE TROUGH WILL BE POISED OVER NV AND UT...CONTINUING TO DRAW A STRONG MOISTURE PLUME UP ACROSS THE 4 CORNERS AND INTO CO. THE TROUGH STEADILY MARCHES TO THE EAST ACROSS COLORADO THROUGH WED AND THU...WITH THE TROUGH AXIS FINALLY REACHING THE OK AND TX PANHANDLES BY FRI MORNING. A GOOD AMOUNT OF MOISTURE...COUPLED WITH AVAILABLE DYNAMICS AND A COLD FRONT WED EVE WILL PROVIDE FOR WIDESPREAD CONVECTION CHANCES THROUGH THE PERIOD...WITH PCPN FINALLY TAPERING OFF FRI MORNING. LOOK FOR SCATTERED POPS FOR MUCH OF THE AREA TUE EVE AND AGAIN WED EVE THROUGH THU...WITH PCPN LIKELY OVER THE MTS. TEMPS ARE EXPECTED TO REMAIN COOLER THROUGH FRI WITH MAX TEMPS IN THE UPPER 70S AND 80S FOR THE PLAINS...AND 60S AND 70S FOR THE HIGH VALLEYS. SATURDAY THROUGH MONDAY...AS THE TROUGH EXITS TO THE EAST...A RIDGE OF HIGH PRESSURE BUILDS OVER THE SW US. THIS WILL HELP A DRYING AND WARMING TREND TO TAKE HOLD OVER THE WEEKEND AND INTO THE FIRST PART OF THE NEXT WORK WEEK. PCPN CHANCES ARE FORECAST TO BE RESTRICTED TO JUST ISOLATED DIURNAL ACTIVITY OVER THE HIGHER TERRAIN...AND TEMPS WILL CLIMB BACK UP INTO THE 80S NEARING 90 F FOR THE PLAINS...AND INTO THE 80S FOR THE HIGH VALLEYS. MOORE && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 305 PM MDT MON AUG 25 2014 TSRA DEVELOPING OVER THE MOUNTAINS WILL CONTINUE TO SPREAD TO LOWER ELEVATIONS THIS AFTERNOON...WITH STORMS NEAR KCOS AND KPUB IN THE 22Z-02Z PERIOD...AND AROUND KALS 22Z-01Z. WITH MORE MOISTURE AVAILABLE TODAY...EXPECT LOWER CLOUD BASES AND RESTRICTED VISIBILITY UNDER THE STRONGEST STORMS...AND LOCAL MVFR/BRIEF IFR CONDITIONS WILL BE POSSIBLE. STORMS WILL GRADUALLY SHIFT INTO NORTHEAST COLORADO THIS EVENING AND OVERNIGHT...WITH A COLD FRONT AND SHIFT TO NORTHEAST WINDS PUSHING SOUTHWARD ACROSS THE PLAINS AFTER 00Z. MAY SEE SOME IFR STRATUS ALONG THE PALMER DIVIDE BY 12Z TUE...BUT HAVEN`T INCLUDED LOWER CLOUDS IN KCOS TAF AS NORTH WIND MAY KEEP CLOUDS JUST NORTH OF THE AIRPORT. ON TUE...EXPECT WIDESPREAD TSRA ALL AREAS...WITH EARLY STORM INITIATION OVER THE MOUNTAINS BY 18Z. BY MID TO LATE AFTERNOON...MTS WILL BE OBSCURED AND MVFR CONDITIONS WITH THUNDERSTORMS WILL BE POSSIBLE AT ALL TAF SITES. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...ROSE SHORT TERM...PETERSEN LONG TERM...MOORE AVIATION...PETERSEN
AREA FORECAST DISCUSSION
NWS PUEBLO CO
305 PM MDT MON AUG 25 2014 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 305 PM MDT MON AUG 25 2014 CURRENTLY...COLD FRONT HAS BECOME STATIONARY NEAR THE NM BORDER THIS AFTERNOON...AND WILL LIKELY DRIFT BACK NORTHWARD TOWARD THE ARKANSAS RIVER BY 00Z. CONVECTION OVER THE MOUNTAINS AND ALONG THE RATON MESA HAS BEEN RELATIVELY WEAK SO FAR AS STORMS HAVE YET TO TAP DEEPER INSTABILITY NEAR THE KS BORDER AND FARTHER NORTH NEAR THE PALMER DIVIDE. WITH COOL AIR SLIGHTLY DEEPER THAN EXPECTED...APPEARS HIGH TEMPS WILL END UP JUST SHY OF FORECAST READINGS. TONIGHT...MESOSCALE MODELS CONTINUE TO POINT TO AREAS ALONG AND NORTH OF THE PALMER DIVIDE HAVING THE BEST CHANCE FOR STRONG/SEVERE CONVECTION...THOUGH LATEST HRRR HINTS AT SOME SOME BRIEF STRONGER STORMS OVER THE FAR EASTERN PLAINS...AS FRONTAL BOUNDARY RETREATING NORTHWARD PROVIDES SOME ENHANCED CONVERGENCE. WEAK SHORT WAVE...OVER WRN CO CURRENTLY...WILL ALSO PROVIDE SOME UPWARD MOTION AS IT CROSSES THE AREA THIS EVENING. BY MIDNIGHT...SUSPECT CONVECTION WILL SHIFT NORTHEAST AND COALESCE INTO AN MCS OVER NWRN KS/SRN NEB...WITH FAIRLY LARGE COLD POOL GIVING SURFACE FRONT A RENEWED SHOVE SOUTHWARD THROUGH THE EASTERN PLAINS. WITH A GRADUAL INCREASE IN MID LEVEL MOISTURE THROUGH THE NIGHT AND BOUNDARY MOVING BACK SOUTHWARD...WILL ONLY GRADUALLY TAPER OFF POPS THROUGH THE EVENING...WITH AT LEAST SOME ISOLATED TSRA POSSIBLE PAST MIDNIGHT. TUESDAY.. UPPER LOW WILL CONTINUE TO SLOWLY PUSH EASTWARD THROUGH THE GREAT BASIN...WITH STRENGTHENING S-SW FLOW AHEAD OF THE SYSTEM PUSHING AN INCREASING AMOUNT OF TROPICAL MOISTURE NORTHWARD INTO COLORADO. SURFACE FRONT WILL LIKELY STAY SOUTH OF THE ARKANSAS RIVER THROUGH THE DAY...WITH E-SE FLOW PUSHING 55F-60F DEWPOINTS WESTWARD TOWARD THE I-25 CORRIDOR. WITH MOISTURE PLENTIFUL...EXPECT EARLY INITIATION OF CONVECTION WITH STORMS FIRING OVER THE MOUNTAINS BEFORE 18Z AND SPREADING QUICKLY TO LOWER ELEVATIONS BY 21Z. MAIN THREAT TOMORROW OVER ALL AREAS WILL BE HEAVY RAINFALL...THOUGH WITH CAPES OVER 1000 J/KG AND 0-6KM SHEAR OF 30-40 KTS...A SEVERE STORM OR TWO IS POSSIBLE ON THE PLAINS MAINLY ALONG AND NORTH OF THE ARKANSAS RIVER. ALL IN ALL...IT LOOKS LIKE A VERY WET DAY OVER MUCH OF SOUTHERN COLORADO...AND WITH CLOUDS AND PRECIP FAIRLY QUICK TO DEVELOP...MAX TEMPS SHOULD COOL AT LEAST A FEW DEGF VERSUS MON READINGS. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 305 PM MDT MON AUG 25 2014 TUESDAY NIGHT THROUGH FRIDAY...LATEST RUNS OF THE NAM...GFS AND EC MODELS ARE IN FAIRLY GOOD AGREEMENT ON THE PROGRESSION OF THE UPPER TROUGH ACROSS THE REGION THROUGH THIS WEEK. TUE EVENING THE TROUGH WILL BE POISED OVER NV AND UT...CONTINUING TO DRAW A STRONG MOISTURE PLUME UP ACROSS THE 4 CORNERS AND INTO CO. THE TROUGH STEADILY MARCHES TO THE EAST ACROSS COLORADO THROUGH WED AND THU...WITH THE TROUGH AXIS FINALLY REACHING THE OK AND TX PANHANDLES BY FRI MORNING. A GOOD AMOUNT OF MOISTURE...COUPLED WITH AVAILABLE DYNAMICS AND A COLD FRONT WED EVE WILL PROVIDE FOR WIDESPREAD CONVECTION CHANCES THROUGH THE PERIOD...WITH PCPN FINALLY TAPERING OFF FRI MORNING. LOOK FOR SCATTERED POPS FOR MUCH OF THE AREA TUE EVE AND AGAIN WED EVE THROUGH THU...WITH PCPN LIKELY OVER THE MTS. TEMPS ARE EXPECTED TO REMAIN COOLER THROUGH FRI WITH MAX TEMPS IN THE UPPER 70S AND 80S FOR THE PLAINS...AND 60S AND 70S FOR THE HIGH VALLEYS. SATURDAY THROUGH MONDAY...AS THE TROUGH EXITS TO THE EAST...A RIDGE OF HIGH PRESSURE BUILDS OVER THE SW US. THIS WILL HELP A DRYING AND WARMING TREND TO TAKE HOLD OVER THE WEEKEND AND INTO THE FIRST PART OF THE NEXT WORK WEEK. PCPN CHANCES ARE FORECAST TO BE RESTRICTED TO JUST ISOLATED DIURNAL ACTIVITY OVER THE HIGHER TERRAIN...AND TEMPS WILL CLIMB BACK UP INTO THE 80S NEARING 90 F FOR THE PLAINS...AND INTO THE 80S FOR THE HIGH VALLEYS. MOORE && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 305 PM MDT MON AUG 25 2014 TSRA DEVELOPING OVER THE MOUNTAINS WILL CONTINUE TO SPREAD TO LOWER ELEVATIONS THIS AFTERNOON...WITH STORMS NEAR KCOS AND KPUB IN THE 22Z-02Z PERIOD...AND AROUND KALS 22Z-01Z. WITH MORE MOISTURE AVAILABLE TODAY...EXPECT LOWER CLOUD BASES AND RESTRICTED VISIBILITY UNDER THE STRONGEST STORMS...AND LOCAL MVFR/BRIEF IFR CONDITIONS WILL BE POSSIBLE. STORMS WILL GRADUALLY SHIFT INTO NORTHEAST COLORADO THIS EVENING AND OVERNIGHT...WITH A COLD FRONT AND SHIFT TO NORTHEAST WINDS PUSHING SOUTHWARD ACROSS THE PLAINS AFTER 00Z. MAY SEE SOME IFR STRATUS ALONG THE PALMER DIVIDE BY 12Z TUE...BUT HAVEN`T INCLUDED LOWER CLOUDS IN KCOS TAF AS NORTH WIND MAY KEEP CLOUDS JUST NORTH OF THE AIRPORT. ON TUE...EXPECT WIDESPREAD TSRA ALL AREAS...WITH EARLY STORM INITIATION OVER THE MOUNTAINS BY 18Z. BY MID TO LATE AFTERNOON...MTS WILL BE OBSCURED AND MVFR CONDITIONS WITH THUNDERSTORMS WILL BE POSSIBLE AT ALL TAF SITES. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...PETERSEN LONG TERM...MOORE AVIATION...PETERSEN
AREA FORECAST DISCUSSION
NWS MIAMI FL
312 PM EDT MON AUG 25 2014 .DISCUSSION...A BACKDOOR TROUGH IS MOVING SOUTHWEST ACROSS THE LOCAL AREA THIS AFTERNOON, BRINGING A SURGE IN MOISTURE ALONG WITH IT. THIS HAS CAUSED SCATTERED FAST MOVING SHOWERS AND JUST A FEW TSTORMS TO AFFECT SOUTH FL. ACTIVITY COULD BECOME SLIGHTLY MORE FOCUSED ALONG THE GULF COAST OVER THE NEXT FEW HR. MAIN IMPACTS WILL BE BRIEF HEAVY DOWNPOURS, GUSTY WINDS AND LIGHTNING STRIKES...THOUGH THERE HAVE NOT BEEN MANY SO FAR TODAY. THE TROUGH WILL MOVE SOUTH OF THE AREA TONIGHT AS CRISTOBAL DISTANCES ITSELF FROM THE BAHAMAS. NE WINDS WILL INCREASE BEHIND IT ALONG WITH SIGNIFICANT DRYING ALOFT. IN FACT...GOES SOUNDER DATA SHOWS PWAT NOW AT AROUND 2 INCHES OVER SOUTH FL...BUT ONLY ABOUT 1.25 INCHES MOVING INTO NORTHEAST FL AND INTO THE ATLANTIC OFF EAST CENTRAL FL. THIS LOWER PWAT AIR WILL MOVE SOUTHWARD AND OVER THE AREA TOMORROW (PUTTING US IN THE LOWER 25TH PERCENTILE FOR THIS TIME OF THE YEAR)...LEADING TO LESS CONVECTIVE ACTIVITY THAN NORMAL FOR SUMMERTIME. HAVE ONLY GONE WITH SLIGHT CHANCE POPS TOMORROW WITH NO TSTORMS EXPECTED. HARD TO GET MUCH "FEEL" CHANGE TO THE AIRMASS THOUGH GIVEN WINDS BLOWING OVER OUR UPPER 80 TO NEAR 90 DEGREE WATERS. STILL...DEWPOINTS ARE FORECAST TO FALL INTO THE LOWER 70S ATLANTIC COAST AND NEAR 70F INTERIOR- GULF COAST WHICH IS BETTER THAN THE UPPER 70-DEGREE DEWPOINTS CURRENTLY IN PLACE THOUGH! THIS "REPRIEVE" WON`T LAST LONG WITH MOISTURE RECOVERY BEGINNING WEDNESDAY WITH A RETURN TO A MORE TYPICAL SUMMERTIME REGIME -- HOT,HUMID WITH SCATTERED AFTERNOON THUNDERSTORMS EACH DAY THROUGH WEEK`S END. /GREGORIA && .MARINE...A SMALL CRAFT ADVISORY WILL BE IN EFFECT FOR THE PALM BEACH AND OFF SHORE GULF WATERS BEGINNING AT 8 PM THIS EVENING AND CONTINUING THROUGH THE NIGHT FOR NE WINDS SUSTAINED NEAR 20 KT. SEAS IN THE GULF STREAM WILL BUILD TO NEAR 7 FEET OVERNIGHT IN RESPONSE. THE SCA MAY NEED TO BE EXTENDED IN TIME FOR THE PALM BEACH WATERS DUE TO HAZARDOUS GULF STREAM SEAS. WINDS/SEAS WILL THEN SUBSIDE MID-LATE WEEK. /GREGORIA && .AVIATION...SCATTERED SHOWERS AND A FEW ISOLATED THUNDERSTORMS CONTINUE TO PUSH SOUTH ACROSS THE AREA THIS AFTERNOON. LATEST HRRR DEPICTS ADDITIONAL SHOWERS THROUGH THE REST OF THE DAY WITHOUT ROBUST CONVECTIVE DEVELOPMENT. THEREFORE REMOVED VCTS MENTION FROM ALL SITES EXCEPT FOR KAPF. HOWEVER...CANNOT RULE OUT AN ISOLATED TSRA TO BRIEFLY AFFECT A TAF SITE THROUGH THE EVENING. WINDS HAVE BEGUN TO TURN MORE NORTHEASTERLY FROM KOPF SOUTHWARD AND SHOULD PREVAIL AROUND 10 KNOTS THROUGH THE NIGHT. /CD && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 79 90 78 90 / 20 20 20 30 FORT LAUDERDALE 81 91 80 91 / 20 20 20 30 MIAMI 80 91 79 91 / 20 20 20 40 NAPLES 78 92 77 91 / 20 20 10 40 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT TUESDAY FOR AMZ650-670. GM...SMALL CRAFT ADVISORY FOR WINDS FROM 8 PM THIS EVENING TO 8 AM EDT TUESDAY FOR GMZ676. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
642 PM EDT MON AUG 25 2014 .SYNOPSIS... HIGH PRESSURE RIDGING INTO THE FORECAST AREA FROM THE NORTH WILL DIRECT DRY AIR INTO THE AREA THROUGH THE END OF THE WORK WEEK. TEMPERATURES WILL BE NEAR NORMAL THROUGH TUESDAY...FOLLOWED BY A WARMING TREND FOR THE LATTER HALF OF THE WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... A LARGE UPPER LEVEL RIDGE EXTENDED FROM THE SOUTHERN PLAINS TO NEW ENGLAND WITH AN UPPER TROUGH WELL OFF THE EAST COAST. SURFACE HIGH PRESSURE STRETCHED FROM THE NORTHEASTERN STATES ACROSS THE CAROLINAS AND GEORGIA. MOIST ONSHORE FLOW COULD BRING AN AREA OF CLOUDS ACROSS THE AREA OVERNIGHT. AFTERNOON SATELLITE LOOP SHOWS SOME SCATTERED/BROKEN AROUND 5K FT MOVING FROM THE PEE DEE INTO THE CENTRAL/EASTERN MIDLANDS. BOTH THE RUC AND NAM INDICATE THIS MOISTURE. MODEL TIME SECTIONS ALSO SHOW A 20 TO 25 KT LOW LEVEL JET AFTER MIDNIGHT AND EXPECT THIS TO KEEP WINDS UP SLIGHTLY OVER LAND AND ALSO OVER THE AREA LAKES. KEPT OVERNIGHT LOWS IN LINE WITH GUIDANCE...RANGING THROUGH THE 60S GIVEN BOUNDARY LAYER MIXING AND PERIOD OF CLOUDS. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... HIGH PRESSURE BOTH AT THE SURFACE AND ALOFT WILL BE IN CONTROL ACROSS THE REGION. THE AIR MASS WILL BE DRY WITH PWAT AT OR BELOW ONE INCH. H850 TEMPERATURES WARM A COUPLE OF DEGREES...RESULTING IN AFTERNOON HIGHS IN THE 85 TO 90 DEGREE RANGE UNDER SUNNY SKIES. GOOD RADIATIONAL COOLING IN DRY AIR MASS WILL ALLOW TEMPERATURES TO COOL INTO THE LOW TO MID 60S AS INDICATED BY GUIDANCE CONSENSUS. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH FRIDAY AS AN UPPER RIDGE BUILDS OVER THE SOUTHEAST. THE UPPER RIDGE WEAKENS A BIT OVER THE WEEKEND AS LOW-LEVEL MOISTURE INCREASES...BUT THE RIDGE STRENGTHENS AGAIN BY MONDAY. EXPECT A CHANCE OF SHOWERS AND THUNDERSTORMS SATURDAY AND SUNDAY WITH A LESSER CHANCE MONDAY. DAYTIME HIGH TEMPERATURES WILL INCREASE TO ABOVE NORMAL THROUGH FRIDAY...AND NEAR NORMAL SATURDAY THROUGH MONDAY. OVERNIGHT LOW TEMPERATURES WILL BE BELOW NORMAL WEDNESDAY AND THURSDAY...AND NEAR NORMAL SATURDAY THROUGH MONDAY. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... HIGH PRESSURE RIDGING INTO THE AREA FROM THE NORTH WILL DOMINATE THROUGH THE TAF PERIOD. MOISTURE FROM THE ATLANTIC IN THE NORTHEAST FLOW WILL AFFECT THE REGION BUT EXPECT THE ASSOCIATED CLOUDINESS WILL BE MAINLY SCATTERED AND BE AROUND 4000 FEET. OBSERVATION TRENDS...THE GFS AND NAM MOS...AND THE SREF GUIDANCE MAINTAIN VFR CONDITIONS. MIXING AND THE DRY NEAR-SURFACE LAYER SHOULD HELP PREVENT FOG DURING THE EARLY MORNING HOURS. USED THE GFS AND NAM MOS FOR THE WIND FORECAST. EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS EXPECTED. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ 77
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
630 PM EDT MON AUG 25 2014 .SYNOPSIS... HIGH PRESSURE RIDGING INTO THE FORECAST AREA FROM THE NORTH WILL DIRECT DRY AIR INTO THE AREA THROUGH THE END OF THE WORK WEEK. TEMPERATURES WILL BE NEAR NORMAL THROUGH TUESDAY...FOLLOWED BY A WARMING TREND FOR THE LATTER HALF OF THE WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... A LARGE UPPER LEVEL RIDGE EXTENDED FROM THE SOUTHERN PLAINS TO NEW ENGLAND WITH AN UPPER TROUGH WELL OFF THE EAST COAST. SURFACE HIGH PRESSURE STRETCHED FROM THE NORTHEASTERN STATES ACROSS THE CAROLINAS AND GEORGIA. WEAK COLD/DRY ADVECTION THIS AFTERNOON WITH PWAT BELOW ONE INCH. SURFACE PRESSURE GRADIENT MODERATELY TIGHT SO EXPECT SOME GUSTY NORTHEAST WINDS THIS AFTERNOON. TEMPERATURES WILL BE SEASONABLE WITH HIGHS RANGING THROUGH THE 80S UNDER SUNNY SKIES. MOIST ONSHORE FLOW COULD BRING AN AREA OF CLOUDS ACROSS THE AREA OVERNIGHT. BOTH THE RUC AND NAM INDICATE THIS MOISTURE. KEPT OVERNIGHT LOWS IN LINE WITH GUIDANCE...RANGING THROUGH THE 60S GIVEN BOUNDARY LAYER MIXING AND PERIOD OF CLOUDS. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... HIGH PRESSURE BOTH AT THE SURFACE AND ALOFT WILL BE IN CONTROL ACROSS THE REGION. THE AIR MASS WILL BE DRY WITH PWAT AT OR BELOW ONE INCH. H850 TEMPERATURES WARM A COUPLE OF DEGREES...RESULTING IN AFTERNOON HIGHS IN THE 85 TO 90 DEGREE RANGE UNDER SUNNY SKIES. GOOD RADIATIONAL COOLING IN DRY AIR MASS WILL ALLOW TEMPERATURES TO COOL INTO THE LOW TO MID 60S AS INDICATED BY GUIDANCE CONSENSUS. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH FRIDAY AS AN UPPER RIDGE BUILDS OVER THE SOUTHEAST. THE UPPER RIDGE WEAKENS A BIT OVER THE WEEKEND AS LOW-LEVEL MOISTURE INCREASES...BUT THE RIDGE STRENGTHENS AGAIN BY MONDAY. EXPECT A CHANCE OF SHOWERS AND THUNDERSTORMS SATURDAY AND SUNDAY WITH A LESSER CHANCE MONDAY. DAYTIME HIGH TEMPERATURES WILL INCREASE TO ABOVE NORMAL THROUGH FRIDAY...AND NEAR NORMAL SATURDAY THROUGH MONDAY. OVERNIGHT LOW TEMPERATURES WILL BE BELOW NORMAL WEDNESDAY AND THURSDAY...AND NEAR NORMAL SATURDAY THROUGH MONDAY. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... HIGH PRESSURE RIDGING INTO THE AREA FROM THE NORTH WILL DOMINATE THROUGH THE TAF PERIOD. MOISTURE FROM THE ATLANTIC IN THE NORTHEAST FLOW WILL AFFECT THE REGION BUT EXPECT THE ASSOCIATED CLOUDINESS WILL BE MAINLY SCATTERED AND BE AROUND 4000 FEET. OBSERVATION TRENDS...THE GFS AND NAM MOS...AND THE SREF GUIDANCE MAINTAIN VFR CONDITIONS. MIXING AND THE DRY NEAR-SURFACE LAYER SHOULD HELP PREVENT FOG DURING THE EARLY MORNING HOURS. USED THE GFS AND NAM MOS FOR THE WIND FORECAST. EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS EXPECTED. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
318 PM EDT MON AUG 25 2014 .SYNOPSIS... HIGH PRESSURE RIDGING INTO THE FORECAST AREA FROM THE NORTH WILL DIRECT DRY AIR INTO THE AREA THROUGH THE END OF THE WORK WEEK. TEMPERATURES WILL BE NEAR NORMAL THROUGH TUESDAY...FOLLOWED BY A WARMING TREND FOR THE LATTER HALF OF THE WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... A LARGE UPPER LEVEL RIDGE EXTENDED FROM THE SOUTHERN PLAINS TO NEW ENGLAND WITH AN UPPER TROUGH WELL OFF THE EAST COAST. SURFACE HIGH PRESSURE STRETCHED FROM THE NORTHEASTERN STATES ACROSS THE CAROLINAS AND GEORGIA. WEAK COLD/DRY ADVECTION THIS AFTERNOON WITH PWAT BELOW ONE INCH. SURFACE PRESSURE GRADIENT MODERATELY TIGHT SO EXPECT SOME GUSTY NORTHEAST WINDS THIS AFTERNOON. TEMPERATURES WILL BE SEASONABLE WITH HIGHS RANGING THROUGH THE 80S UNDER SUNNY SKIES. MOIST ONSHORE FLOW COULD BRING AN AREA OF CLOUDS ACROSS THE AREA OVERNIGHT. BOTH THE RUC AND NAM INDICATE THIS MOISTURE. KEPT OVERNIGHT LOWS IN LINE WITH GUIDANCE...RANGING THROUGH THE 60S GIVEN BOUNDARY LAYER MIXING AND PERIOD OF CLOUDS. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... HIGH PRESSURE BOTH AT THE SURFACE AND ALOFT WILL BE IN CONTROL ACROSS THE REGION. THE AIR MASS WILL BE DRY WITH PWAT AT OR BELOW ONE INCH. H850 TEMPERATURES WARM A COUPLE OF DEGREES...RESULTING IN AFTERNOON HIGHS IN THE 85 TO 90 DEGREE RANGE UNDER SUNNY SKIES. GOOD RADIATIONAL COOLING IN DRY AIR MASS WILL ALLOW TEMPERATURES TO COOL INTO THE LOW TO MID 60S AS INDICATED BY GUIDANCE CONSENSUS. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH FRIDAY AS AN UPPER RIDGE BUILDS OVER THE SOUTHEAST. THE UPPER RIDGE WEAKENS A BIT OVER THE WEEKEND AS LOW-LEVEL MOISTURE INCREASES...BUT THE RIDGE STRENGTHENS AGAIN BY MONDAY. EXPECT A CHANCE OF SHOWERS AND THUNDERSTORMS SATURDAY AND SUNDAY WITH A LESSER CHANCE MONDAY. DAYTIME HIGH TEMPERATURES WILL INCREASE TO ABOVE NORMAL THROUGH FRIDAY...AND NEAR NORMAL SATURDAY THROUGH MONDAY. OVERNIGHT LOW TEMPERATURES WILL BE BELOW NORMAL WEDNESDAY AND THURSDAY...AND NEAR NORMAL SATURDAY THROUGH MONDAY. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... VFR CONDITIONS EXPECTED TO CONTINUE THROUGH THE 24-HOUR TAF PERIOD. SURFACE HIGH PRESSURE CONTINUES BUILDING DOWN THE EASTERN SEABOARD...COUPLED WITH AN UPPER RIDGE OVERHEAD. CLEAR SKIES THIS AFTERNOON. MODELS INDICATE AN INCREASE IN CLOUDS 4-6KFT OVERNIGHT IN MOIST ONSHORE FLOW. NORTHEAST WINDS 10 TO 15 KNOTS WITH GUST NEAR 20 KNOTS THIS AFTERNOON WILL DIMINISH WITH SUNSET. EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION EXPECTED. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
210 PM EDT MON AUG 25 2014 .SYNOPSIS... HIGH PRESSURE RIDGING INTO THE FORECAST AREA FROM THE NORTH WILL DIRECT DRY AIR INTO THE AREA THROUGH THE END OF THE WORK WEEK. TEMPERATURES WILL BE NEAR NORMAL THROUGH TUESDAY...FOLLOWED BY A WARMING TREND FOR THE LATTER HALF OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... A LARGE UPPER LEVEL RIDGE EXTENDED FROM THE SOUTHERN PLAINS TO NEW ENGLAND WITH AN UPPER TROUGH WELL OFF THE EAST COAST. SURFACE HIGH PRESSURE STRETCHED FROM THE NORTHEASTERN STATES ACROSS THE CAROLINAS AND GEORGIA. WEAK COLD/DRY ADVECTION THIS AFTERNOON WITH PWAT BELOW ONE INCH. SURFACE PRESSURE GRADIENT MODERATELY TIGHT SO EXPECT SOME GUSTY NORTHEAST WINDS THIS AFTERNOON. TEMPERATURES WILL BE SEASONABLE WITH HIGHS RANGING THROUGH THE 80S UNDER SUNNY SKIES. MOIST ONSHORE FLOW COULD BRING AN AREA OF CLOUDS ACROSS THE AREA OVERNIGHT. BOTH THE RUC AND NAM INDICATE PWAT INCREASING TO NEAR 2.00 INCHES WITH AN INCREASE IN H850 MOISTURE. KEPT OVERNIGHT LOWS IN LINE WITH GUIDANCE...RANGING THROUGH THE 60S GIVEN BOUNDARY LAYER MIXING AND PERIOD OF CLOUDS. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... HIGH PRESSURE BOTH AT THE SURFACE AND ALOFT WILL BE IN CONTROL ACROSS THE REGION. THE AIR MASS WILL BE DRY WITH PWAT AT OR BELOW ONE INCH. H850 TEMPERATURES WARM A COUPLE OF DEGREES...RESULTING IN AFTERNOON HIGHS IN THE 85 TO 90 DEGREE RANGE UNDER SUNNY SKIES. GOOD RADIATIONAL COOLING IN DRY AIRMASS WILL ALLOW TEMPERATURES TO COOL INTO THE LOW TO MID 60S AS INDICATED BY GUIDANCE CONSENSUS. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH FRIDAY AS AN UPPER RIDGE BUILDS OVER THE SOUTHEAST. THE UPPER RIDGE WEAKENS A BIT OVER THE WEEKEND AS LOW-LEVEL MOISTURE INCREASES...BUT THE RIDGE STRENGTHENS AGAIN BY MONDAY. EXPECT A CHANCE OF SHOWERS AND THUNDERSTORMS SATURDAY AND SUNDAY WITH A LESSER CHANCE MONDAY. DAYTIME HIGH TEMPERATURES WILL INCREASE TO ABOVE NORMAL THROUGH FRIDAY...AND NEAR NORMAL SATURDAY THROUGH MONDAY. OVERNIGHT LOW TEMPERATURES WILL BE BELOW NORMAL WEDNESDAY AND THURSDAY...AND NEAR NORMAL SATURDAY THROUGH MONDAY. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... VFR CONDITIONS EXPECTED TO CONTINUE THROUGH THE 24 HOUR TAF PERIOD. SURFACE HIGH PRESSURE CONTINUES BUILDING DOWN THE EASTERN SEABOARD...COUPLED WITH AN UPPER RIDGE OVERHEAD. CLEAR SKIES THIS AFTERNOON. MODELS INDICATE AN INCREASE IN CLOUDS 4-6KFT OVERNIGHT IN MOIST ONSHORE FLOW. NORTHEAST WINDS 10 TO 15 KNOTS WITH GUST NEAR 20 KNOTS THIS AFTERNOON WILL DIMINISH WITH SUNSET. EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION EXPECTED. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
317 PM CDT MON AUG 25 2014 .DISCUSSION... 315 PM CDT SHORT TERM...THROUGH EARLY TUESDAY MORNING... FOR THE REMAINDER OF THE AFTERNOON...MAIN FOCUS WILL CONTINUE TO BE 2 LINES OF THUNDERSTORMS...ONE MOVING THROUGH NWRN IL AND ANOTHER MOVING THROUGH NWRN IN AND ECNTRL IL. THESE LINES ARE PRODUCING STRONG TO OCNLY SVR TS...WITH THE PRIMARY THREAT BEING WIND GUSTS TO 60 MPH AND TORRENTIAL DOWNPOURS. THE TREND WITH TIME SHOULD BE FOR THE LINE OVER NWRN IL TO BEGIN TO WEAKEN AS IT MOVES INTO AN AIRMASS OVER NERN IL WHICH HAS BEEN WORKED OVER BY EARLIER CONVECTION. THE LINE ACROSS NWRN IN INTO ECNTRL IL SHOULD MAINTAIN SOME STRENGTH AS IT CONTINUES TO PUSH SEWD. LATEST RADAR IMAGERY SHOWS A DISTINCT OUTFLOW BOUNDARY EXTENDING WEST FROM KANKAKEE TO PERU WHICH COULD YET BE THE FOCUS FOR SOME ADDITIONAL THUNDERSTORM DEVELOPMENT INTO THE EARLY EVENING HOURS. THUNDERSTORMS HAVE HAD A HISTORY OF PRODUCING IN EXCESS OF 1 INCH IN 30 MINUTES...BUT SINCE THEY HAVE BEEN PROGRESSIVE...SIGNIFICANT WIDESPREAD FLOODING IS NOT ANTICIPATED...THOUGH LOCALLY HEAVY RAINFALL COULD PRODUCE URBAN ANS SMALL STREAM TYPE FLOODING. EXPECT THAT THE POTENTIAL FOR ORGANIZED THUNDERSTORMS SHOULD DIMINISH INTO EARLY THIS EVENING WITH THE SETTING SUN AND LARGER SCALE SUBSIDENCE MOVES OVER THE AREA AS WEAK SHORT WAVE RIDGING MOVES OVER THE AREA TONIGHT. AS THE THUNDERSTORM ACTIVITY DIMINISHES THIS EVENING...PATCHY FOG AND WIDESPREAD MISTY/MURKY CONDITIONS WILL SET UP. WHILE WIDESPREAD DENSE FOG IS NOT LIKELY DUE TO PERSISTENT DEBRIS CLOUD FROM EARLIER CONVECTION...A VERY MOIST ENVIRONMENT WILL REMAIN IN PLACE...AND COMBINED WITH LIGHT WINDS CONDITIONS WILL REMAIN MUGGY OVERNIGHT. THE TEMPERATURE FORECAST FOR TODAY WAS DISRUPTED BY THE THUNDERSTORMS AND EXTENSIVE CLOUD COVER OVER AREAS IMPACTED BY THE THUNDERSTORMS. HOWEVER...LOCATIONS SOUTH OF A LINE FROM MIDWAY AIRPORT TO PERU STILL SAW MAX HEAT INDICES IN EXCESS OF 100F WHILE LOCATIONS SOUTH OF THE ILLINOIS/KANKAKEE RIVERS SAW HEAT INDICES APPROACH OR SLIGHTLY EXCEED 110F. TEMPERATURES AND DEWPOINTS SHOULD REMAIN IN THE LOWER TO MIDDLE 70S OVERNIGHT AS THERE WILL BE NO SGFNT CHANGE IN AIRMASS. WITH OLD OUTFLOW BOUNDARIES HANGING AROUND THE AREA OVERNIGHT...THERE WILL STILL BE SOME LOW CHANCES FOR ADDITIONAL SHOWERS OR THUNDERSTORMS AS A WEAK COLD FRONT MOVES DOWN THE LAKE AND INTO THE WARM...HUMID ENVIRONMENT. KREIN LONG TERM DISCUSSION COMING SOON... && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * WINDS TURNING NE ARND 10-12KT...WITH AN OCCASIONAL GUSTS TO 20-25KT. * WIND SPEEDS DIMINISH TO ARND 6-8KT LATE AFTN/EARLY EVE...THEN TURN W/NW. * POSSIBLE ADDTL ISOLATED TSRA OVERNIGHT/EARLY TUE MORNING. * PATCHY FOG DEVELOPING AFT 04Z...MAY REDUCE VSBYS TO ARND 2-4SM. WEST OF TAF SITES VSBYS COULD BE LOWER. BEACHLER //DISCUSSION...UPDATED 18Z... SPOTTY SHOWERS AND THUNDERSTORMS HAVE CONTINUED TO DEVELOP ALONG AN ORIGINAL OUTFLOW BOUNDARY ACROSS NORTHEAST IL. ADDTL SHRA/TSRA HAVE DEVELOPED WEST OF TAF SITES...WITH A FEW STRONGER STORMS CAPABLE OF PRODUCING WIND GUSTS TO 40KTS THIS AFTN. CONCERN IS THAT A WEAK BOUNDARY SLIDING SOUTH AND A LACK OF A GRADIENT...WILL ONLY PROLONG THE NORTHEAST WINDS AT ORD/MDW. MEANWHILE FURTHER WEST AT RFD/DPA THE WINDS SHUD BE ABLE TO TURN NW/W ARND 20-21Z. WILL CONTINUE TO MENTION VCTS THRU 23Z...AND IF ADDTL STORMS ARE ABLE TO DEVELOP WE WILL LIKELY NEED TO ADJUST WITH A TEMPO BUT COVERAGE IS NOT EXPECTED TO BE THERE. THEN LATE THIS EVENING GUIDANCE IS SUGGESTING THE WINDS WILL BECOME LGT FROM THE NW ARND 5-8KT. THE CONCERN THEN WILL TURN TOWARDS THE LOW CIGS BUT ALSO THE POTENTIAL FOR PATCHY FOG TO DEVELOP GIVEN HOW MOIST THE ENVIRONMENT WILL REMAIN OVERNIGHT. FOG MAY BEGIN TO DISSIPATE AFT DAYBREAK TUE...THEN GUIDANCE SUGGESTS THE WINDS WILL TRY TO TURN NW WITH SPEEDS ARND 8-11KT. BEACHLER //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE IN TSRA REMAINING ISOLATED...LOW CONFIDENCE IN PRECISE TIMING/INTENSITY AT TAF SITES. * HIGH CONFIDENCE IN WINDS REMAINING NORTHEAST THRU 22Z...THEN LOW CONFIDENCE IN TIMING OF WINDS TURNING NW LATE AFTN/EARLY EVE. * MEDIUM CONFIDENCE IN PATCHY FOG DEVELOPING. BEACHLER //OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z... * TUESDAY NIGHT...TSRA LIKELY. * WEDNESDAY THROUGH SUNDAY...CHANCE OF TSRA. && .MARINE... 243 AM...LOW PRESSURE OVER SOUTHERN MANITOBA WILL MOVE ACROSS NORTHERN ONTARIO TODAY AND TONIGHT REACHING JAMES BAY TUESDAY MORNING. A TRAILING COLD FRONT WILL SLOWLY SAG SOUTHEAST ACROSS THE WESTERN LAKES AND REACH NORTHERN LAKE MICHIGAN BY DAYBREAK TUESDAY MORNING. THIS FRONT WILL THEN CONTINUE SOUTH ACROSS LAKE MICHIGAN TUESDAY AND EVENTUALLY STALL NEAR OR JUST SOUTH OF THE LAKE WEDNESDAY INTO THURSDAY. AHEAD OF THIS FRONT...SOUTH TO SOUTHEAST WINDS 10-20KTS WILL GRADUALLY SHIFT MORE SOUTHWESTERLY LATER TODAY AND THIS EVENING. A FEW HIGHER GUSTS ARE POSSIBLE BUT THE TIGHTEST PORTION OF THE GRADIENT PASSES NORTH OF THE LAKE. HIGH PRESSURE WILL BUILD ACROSS THE NORTHERN PLAINS ON TUESDAY AND THEN MOVE ACROSS THE NORTHERN LAKES WEDNESDAY. THIS MAY STRENGTHEN THE GRADIENT A BIT ON THE SOUTHERN END OF THE LAKE WITH A PROLONGED NORTHEAST FLOW IN THE 10-20KT RANGE POSSIBLE. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...HEAT ADVISORY...ILZ010-ILZ019-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 10 PM MONDAY. 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
  [top] Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 314 PM CDT Mon Aug 25 2014 .SHORT TERM...(This evening through Tuesday) ISSUED AT 312 PM CDT MON AUG 25 2014 Hot and very humid conditions are the rule across central Illinois this afternoon, with 19z/2pm temperatures in the lower to middle 90s across the board. Further north, clusters of thunderstorms have developed along outflow boundaries from eastern Iowa across northern Illinois. This convection is generally tracking eastward, with a slight southeastward drift. High-res models are once again handling the convection quite poorly, with the 2-hr HRRR forecast completely missing the storms currently ongoing south of Chicago. The Chicago storm complex will continue developing E/SE into northwest Indiana over the next couple of hours. Meanwhile, we will have to keep an eye on additional storms just north of Moline. These cells will likely track E/SE along an outflow boundary evident on satellite/radar imagery and should remain just north of the KILX CWA. Have included a slight chance PoP along/northeast of a Henry to Danville late this afternoon into the early evening in case they develop a bit further southward. A cold front currently analyzed across central Iowa will gradually push eastward over the next 12 to 24 hours, reaching the northern KILX CWA by Tuesday morning. Many of the 12z models show little or no convection with the boundary overnight, but have included low chance PoPs along/northwest of a Rushville to Bloomington line as the front encounters a very moist airmass. Aside from any scattered convection that may develop, the potential for fog will once again be an issue overnight. Light/variable winds along with dewpoint pooling along the boundary will favor fog, but increased mid/high clouds may tend to mitigate it somewhat. Based on an unchanged airmass and persistence from the past several nights, have included patchy fog in the forecast after midnight. Any fog will dissipate early Tuesday morning, followed by partly to mostly sunny conditions across the southern half of the CWA. Further north in closer proximity to the nearly stationary frontal boundary, mostly cloudy skies and scattered convection will keep temps slightly cooler than they have been recently. High temps on Tuesday will range from the upper 80s north to the middle 90s along/south of I-70. Due to the slightly cooler temps, heat index readings across the north may not reach advisory criteria. May need to drop the advisory for the Peoria area northward, as heat index values will likely remain in the 95 to 100 degree range on Tuesday. && .LONG TERM...(Tuesday night through Monday) ISSUED AT 312 PM CDT MON AUG 25 2014 A frontal boundary will become somewhat stationary over the area and is forecast to remain there through the rest of the week and into the weekend. This will become the focus for thunderstorms throughout the period. Thunderstorms will not be continuous throughout the period, but trying to time when the dry, or drier, periods is going to be is the main forecast challenge. Due to the difficulty of timing the precip periods and the dry periods during the medium and long ranges of the forecast, best to just have chance pcpn through the period over the whole area. Will have likely pops in the north third of the CWA for Tue night, but remainder of the forecast will just be chance across the area. With the frontal boundary getting into the area, relatively cooler air will advect into the area. Temperatures will gradually drop back to around normal, which is middle to upper 80s, by the weekend. However, with all the moisture forecasted over the area, muggy/humid conditions will continue through the period. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) ISSUED AT 1248 PM CDT MON AUG 25 2014 Mostly sunny skies will prevail across central Illinois today, as convection remains along/north of the I-80 corridor. Latest satellite imagery shows clear skies across much of the area, with just FEW-SCT diurnal clouds developing near KBMI and KCMI. Cold front currently analyzed across central Iowa will drop southeastward tonight, eventually settling into north-central Illinois by Tuesday morning. With boundary approaching, winds will go light/variable, once again setting up the potential for fog overnight. Forecast soundings and numeric guidance support fog development, so have included reduced visbys of 3 to 5 miles between 08z and 14z. Am not expecting much in the way of thunderstorm development through 18z, although have introduced a mid-level cloud deck at KPIA as the front arrives late tonight into Tuesday morning. && .ILX WATCHES/WARNINGS/ADVISORIES... EXCESSIVE HEAT WARNING until 7 PM CDT Tuesday FOR ILZ042-047>054- 056-061>063-066>068-071>073. HEAT ADVISORY until 7 PM CDT Tuesday FOR ILZ027>031-036>038-040- 041-043>046-055-057. && $$ SHORT TERM...BARNES LONG TERM...AUTEN AVIATION...BARNES
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
228 PM EDT MON AUG 25 2014 .SYNOPSIS... ISSUED AT 1056 AM EDT MON AUG 25 2014 HOT AND MUGGY CONDITIONS ACROSS THE REGION TODAY INTO TONIGHT. DEWPOINTS IN THE LOWER 70S WILL CREATE MUGGY CONDITIONS AS HIGH PRESSURE RETAINS ITS INFLUENCE OVER US. A FRONTAL SYSTEM TO THE WEST COULD INTRODUCE SOME RAIN TO THE NORTHERN PORTION OF THE REGION TONIGHT AS IT APPROACHES. HIGH TEMPERATURES TODAY WILL BE IN THE UPPER 80S TO AROUND 90 WITH THE HEAT INDEX IN THE 90S TO NEAR 100. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE UPPER 60S NEAR THE OHIO RIVER TO THE LOWER 70S IN SOUTHERN MICHIGAN. && .UPDATE... ISSUED AT 1242 PM EDT MON AUG 25 2014 FOCUS FOR THE REMAINDER OF THE AFTERNOON WILL CENTER ON CONVECTIVE POTENTIAL AND HEAT. RESIDUAL OUTFLOW BOUNDARY FROM UPSTREAM CONVECTION HAS ALLOWED FOR RENEWED THUNDERSTORM DEVELOPMENT ACROSS NORTHEAST ILLINOIS. REMNANT OUTFLOW/CONVECTIVE VORT FROM UPSTREAM CONVECTION WILL HAVE PLENTY OF DOWNSTREAM INSTABILITY TO WORK THIS AFTERNOON WITH INDICATIONS IN RUC SHORT TERM PROGS OF 3-4K J/KG OF 100 HPA MLCAPES WORKING INTO WESTERN PORTIONS OF THE AREA. DEEP LAYER SHEAR IS WEAK...BUT GIVEN MAGNITUDE OF INSTABILITY WILL HAVE TO MONITOR FOR POSSIBILITY OF ISOLATED STRONG/SEVERE STORMS THIS AFTERNOON. WITH EARLY AFTERNOON UPDATE...WILL GO AHEAD AND MAKE SOME SOUTHEAST EXPANSION OF SLIGHT CHANCE AND PERHAPS RAISE POPS A BIT IN THE FAR NORTHWEST DUE TO APPROACH OF OUTFLOW BOUNDARY. TEMPERATURES/DEW POINTS APPEAR TO BE IN GOOD SHAPE WITH PEAK AFTERNOON HEAT INDICES STILL LIKELY TO REACH INTO THE UPPER 90S ACROSS THE WEST. WILL CONTINUE TO GO WITH CURRENT SPS FOR THIS AFTERNOON TO HIGHLIGHT HAZARDOUS CONDITIONS ASSOCIATED WITH THE HEAT/HUMIDITY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 404 AM EDT MON AUG 25 2014 FOCUS OF PERIOD WILL BE TWO FOLD...TEMPERATURES/HEAT INDEX ISSUES AND CHANCES FOR STORMS. WARM AND MUGGY CONDITIONS WERE IN PLACE ACROSS THE AREA WITH TEMPERATURES IN THE 70S AND DEWPOINTS IN THE UPPER 60S NE TO LOWER 70S SW WITH MOST UNSTABLE CAPE VALUES IN THE 500 TO 1500 J/KG RANGE. WITH NO REAL TRIGGER ACROSS THE AREA NO SHOWERS/STORMS HAVE FORMED THUS FAR. MAIN FOCUS FOR STORMS HAS BEEN FROM NORTHERN WISCONSIN INTO PORTIONS OF CENTRAL IOWA WHERE 30 TO 35 KT LOW LEVEL JET WAS AIDING IN DEVELOPMENT AND MAINTENANCE OF A BROKEN LINE OF STRONG TO LOCALLY SEVERE STORMS. HI RES MODELS ALL SUGGEST THIS LINE WILL DROP SLOWLY SOUTHEAST BUT VARY IN HOW MUCH HOLD TOGETHER AS WE APPROACH 12Z MON AND POINTS BEYOND. WOULD SEEM REASONABLE THAT SOME SORT OF OUTFLOW BOUNDARY OR REMNANT SHOWERS/STORMS COULD APPROACH NW AREAS THIS AFTERNOON AND THEN STALL SOMEWHERE TONIGHT BEING REINFORCED SOMEWHAT BY SFC FRONT THAT WILL BE SINKING SOUTH. ONLY CHANGE TO GRIDS WILL BE REORIENTATION OF SLGT CHC POPS TO MORE OF A SW TO NE ORIENTATION. IF SUFFICIENT HEATING TAKES PLACE AND PROGGED INSTABILITY IS AVAILABLE (SURFACE BASED CAPES IN EXCESS OF 4000 J/KG IN A WEAKLY SHEAR ENVIRONMENT) THEN SOME STRONGER STORMS COULD BE A CONCERN. NOW FOR TEMPERATURES...THE WARM START TO THE MORNING SHOULD ALLOW TEMPERATURES TO QUICKLY CLIMB INTO THE 80S BY NOON TIME AND POSSIBLY CLOSE TO 90 IN WESTERN AREAS. DEWPOINTS IN WESTERN AREAS LOOK TO CLIMB INTO THE MIDDLE 70S IN SOME SPOTS WHICH IF TEMPS DO APPROACH 90 WILL EDGE REAL CLOSE TO HEAT ADVISORY LEVELS (EVEN BRIEFLY TOUCH IN FAR WEST). WILL HANDLE WITH HWO AND SPS FOR NOW AND LET DAY SHIFT ASSESS THINGS AFTER SUNRISE AS TO EXTENT OF CLOUD COVER AND POSSIBLE INFLUENCE FROM UPSTREAM CONVECTION. LOWS TONIGHT WILL DROP BACK INTO THE UPR 60S TO LOWER 70S. && .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 404 AM EDT MON AUG 25 2014 LOW OVER SRN MANITOBA THIS MORNING EXPECTED TO LIFT NE INTO QUEBEC TUESDAY WITH TRAILING CDFNT MOVG INTO OUR CWA. WK FORCING ALONG THE FRONT COMBINED WITH SOME CAPPING ASSOCIATED WITH UPR RIDGE OVER THE OH/MID MS VALLEY LIMITS TSTM POTENTIAL TO CHC DESPITE AT LEAST MODERATE INSTABILITY IN PLACE OVER THE AREA. TEMPS WILL REMAIN ABOVE NORMAL WITH HIGHS IN THE UPPER 80S AND PM HEAT INDEX READINGS IN THE 90S. CDFNT EXPECTED TO SAG SOUTH INTO CENTRAL OH/IN TUE NGT. POTENTIAL FOR TSTMS INCREASES A BIT IN THIS TIMEFRAME AS A SHRTWV CURRENTLY OVER WRN CANADA MOVES TO THE UPR GRTLKS RESULTING IN MINOR HEIGHT FALLS AS FAR SOUTH AS OUR CWA. WK CAA SHOULD ALLOW FOR LOWS TO FALL INTO THE M-U60S ACROSS THE AREA. RAIN CHANCES DIMINISH WED-WED NGT AS FRONT CONTS TO SAG SOUTH TO THE OH VALLEY AND SFC HIGH MOVES ESE INTO THE UPR GRTLKS. TEMPS SHOULD FALL BACK CLOSER TO NORMAL WITH HIGHS IN THE L80S AND LOWS IN THE L-M60S. FRONTAL SYSTEM EXPECTED TO LIFT BACK NORTH INTO OUR AREA THU-THU NGT AS SFC HIGH MOVES TO THE MID ATLANTIC/NORTHEAST U.S.. DVLPG SPLIT FLOW CUT-OFF LOW OVER THE WRN U.S. BY MID WEEK IS EXPECTED TO MOVE SLOWLY EAST TO THE CENTRAL PLAINS FRIDAY AND INTO THE MID MS VALLEY BY SUNDAY WHILE SFC BOUNDARY LINGERS OVER THE AREA... ENHANCING TSTM POTENTIAL ACROSS OUR AREA OVER THE LABOR DAY WEEKEND... WHILE TEMPS REMAIN CLOSE TO NORMAL. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 200 PM EDT MON AUG 25 2014 AN OUTFLOW BOUNDARY ASSOCIATED WITH OVERNIGHT UPSTREAM CONVECTION HAS BEEN A TRIGGER MECHANISM FOR SHOWERS AND THUNDERSTORMS ACROSS NORTHEAST ILLINOIS AND SOUTHERN LOWER MICHIGAN. THIS BOUNDARY SHOULD CONTINUE TO DROP INTO NORTH CENTRAL INDIANA BY 20Z. A STRONGLY UNSTABLE ENVIRONMENT EXISTS ACROSS THE AREA...WITH MAIN NEGATIVE FACTOR TO SOUTHEAST EXPANSION OF THE SHOWERS AND STORMS IS BACKGROUND WEAK UPPER FORCING AND PRESENCE OF MID/UPPER LEVEL RIDGING. HAVE CARRIED A VCTS MENTION AT KSBN FROM 20Z-22Z AND WILL BE MONITORING TRENDS OVER NEXT HOUR OR SO FOR POSSIBLE TSRA INCLUSION. SOUTH WINDS AT KSBN MAY BECOME NORTHWEST FOR A TIME IN THE 20Z-22Z TIMEFRAME DUE TO THE PASSAGE OF THE OUTFLOW BOUNDARY...OR VARIABLE IN NATURE. A SHEARED UPPER VORT MAX FROM CENTRAL WISCONSIN INTO EASTERN IOWA WILL TRACK INTO NORTHWEST INDIANA THIS EVENING WITH SOME POSSIBILITY OF ADDITIONAL ISOLATED THUNDERSTORMS. OTHER THAN PASSAGE OF THIS WEAK WAVE THIS EVENING...FORCING WILL BE SOMEWHAT WEAK WITH LOW CONFIDENCE IN TIMING AND WILL KEEP TAFS DRY THROUGH THE END OF THE PERIOD. CHANCES OF THUNDER MAY INCREASE LATE TONIGHT INTO TUESDAY MORNING AS LOW LEVEL FRONT BEGINS TO APPROACH THE AREA...BUT CONFIDENCE REMAINS LOW IN TIMING/COVERAGE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...MARSILI SYNOPSIS...LOTHAMER SHORT TERM...FISHER LONG TERM...JT AVIATION...MARSILI VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1259 PM EDT MON AUG 25 2014 .SYNOPSIS... ISSUED AT 1056 AM EDT MON AUG 25 2014 HOT AND MUGGY CONDITIONS ACROSS THE REGION TODAY INTO TONIGHT. DEWPOINTS IN THE LOWER 70S WILL CREATE MUGGY CONDITIONS AS HIGH PRESSURE RETAINS ITS INFLUENCE OVER US. A FRONTAL SYSTEM TO THE WEST COULD INTRODUCE SOME RAIN TO THE NORTHERN PORTION OF THE REGION TONIGHT AS IT APPROACHES. HIGH TEMPERATURES TODAY WILL BE IN THE UPPER 80S TO AROUND 90 WITH THE HEAT INDEX IN THE 90S TO NEAR 100. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE UPPER 60S NEAR THE OHIO RIVER TO THE LOWER 70S IN SOUTHERN MICHIGAN. && .UPDATE... ISSUED AT 1242 PM EDT MON AUG 25 2014 FOCUS FOR THE REMAINDER OF THE AFTERNOON WILL CENTER ON CONVECTIVE POTENTIAL AND HEAT. RESIDUAL OUTFLOW BOUNDARY FROM UPSTREAM CONVECTION HAS ALLOWED FOR RENEWED THUNDERSTORM DEVELOPMENT ACROSS NORTHEAST ILLINOIS. REMNANT OUTFLOW/CONVECTIVE VORT FROM UPSTREAM CONVECTION WILL HAVE PLENTY OF DOWNSTREAM INSTABILITY TO WORK THIS AFTERNOON WITH INDICATIONS IN RUC SHORT TERM PROGS OF 3-4K J/KG OF 100 HPA MLCAPES WORKING INTO WESTERN PORTIONS OF THE AREA. DEEP LAYER SHEAR IS WEAK...BUT GIVEN MAGNITUDE OF INSTABILITY WILL HAVE TO MONITOR FOR POSSIBILITY OF ISOLATED STRONG/SEVERE STORMS THIS AFTERNOON. WITH EARLY AFTERNOON UPDATE...WILL GO AHEAD AND MAKE SOME SOUTHEAST EXPANSION OF SLIGHT CHANCE AND PERHAPS RAISE POPS A BIT IN THE FAR NORTHWEST DUE TO APPROACH OF OUTFLOW BOUNDARY. TEMPERATURES/DEW POINTS APPEAR TO BE IN GOOD SHAPE WITH PEAK AFTERNOON HEAT INDICES STILL LIKELY TO REACH INTO THE UPPER 90S ACROSS THE WEST. WILL CONTINUE TO GO WTIH CURRENT SPS FOR THIS AFTERNOON TO HIGHLIGHT HAZARDOUS CONDITIONS ASSOCIATED WITH THE HEAT/HUMIDITY. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 404 AM EDT MON AUG 25 2014 FOCUS OF PERIOD WILL BE TWO FOLD...TEMPERATURES/HEAT INDEX ISSUES AND CHANCES FOR STORMS. WARM AND MUGGY CONDITIONS WERE IN PLACE ACROSS THE AREA WITH TEMPERATURES IN THE 70S AND DEWPOINTS IN THE UPPER 60S NE TO LOWER 70S SW WITH MOST UNSTABLE CAPE VALUES IN THE 500 TO 1500 J/KG RANGE. WITH NO REAL TRIGGER ACROSS THE AREA NO SHOWERS/STORMS HAVE FORMED THUS FAR. MAIN FOCUS FOR STORMS HAS BEEN FROM NORTHERN WISCONSIN INTO PORTIONS OF CENTRAL IOWA WHERE 30 TO 35 KT LOW LEVEL JET WAS AIDING IN DEVELOPMENT AND MAINTENANCE OF A BROKEN LINE OF STRONG TO LOCALLY SEVERE STORMS. HI RES MODELS ALL SUGGEST THIS LINE WILL DROP SLOWLY SOUTHEAST BUT VARY IN HOW MUCH HOLD TOGETHER AS WE APPROACH 12Z MON AND POINTS BEYOND. WOULD SEEM REASONABLE THAT SOME SORT OF OUTFLOW BOUNDARY OR REMNANT SHOWERS/STORMS COULD APPROACH NW AREAS THIS AFTERNOON AND THEN STALL SOMEWHERE TONIGHT BEING REINFORCED SOMEWHAT BY SFC FRONT THAT WILL BE SINKING SOUTH. ONLY CHANGE TO GRIDS WILL BE REORIENTATION OF SLGT CHC POPS TO MORE OF A SW TO NE ORIENTATION. IF SUFFICIENT HEATING TAKES PLACE AND PROGGED INSTABILITY IS AVAILABLE (SURFACE BASED CAPES IN EXCESS OF 4000 J/KG IN A WEAKLY SHEAR ENVIRONMENT) THEN SOME STRONGER STORMS COULD BE A CONCERN. NOW FOR TEMPERATURES...THE WARM START TO THE MORNING SHOULD ALLOW TEMPERATURES TO QUICKLY CLIMB INTO THE 80S BY NOON TIME AND POSSIBLY CLOSE TO 90 IN WESTERN AREAS. DEWPOINTS IN WESTERN AREAS LOOK TO CLIMB INTO THE MIDDLE 70S IN SOME SPOTS WHICH IF TEMPS DO APPROACH 90 WILL EDGE REAL CLOSE TO HEAT ADVISORY LEVELS (EVEN BRIEFLY TOUCH IN FAR WEST). WILL HANDLE WITH HWO AND SPS FOR NOW AND LET DAY SHIFT ASSESS THINGS AFTER SUNRISE AS TO EXTENT OF CLOUD COVER AND POSSIBLE INFLUENCE FROM UPSTREAM CONVECTION. LOWS TONIGHT WILL DROP BACK INTO THE UPR 60S TO LOWER 70S. && .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 404 AM EDT MON AUG 25 2014 LOW OVER SRN MANITOBA THIS MORNING EXPECTED TO LIFT NE INTO QUEBEC TUESDAY WITH TRAILING CDFNT MOVG INTO OUR CWA. WK FORCING ALONG THE FRONT COMBINED WITH SOME CAPPING ASSOCIATED WITH UPR RIDGE OVER THE OH/MID MS VALLEY LIMITS TSTM POTENTIAL TO CHC DESPITE AT LEAST MODERATE INSTABILITY IN PLACE OVER THE AREA. TEMPS WILL REMAIN ABOVE NORMAL WITH HIGHS IN THE UPPER 80S AND PM HEAT INDEX READINGS IN THE 90S. CDFNT EXPECTED TO SAG SOUTH INTO CENTRAL OH/IN TUE NGT. POTENTIAL FOR TSTMS INCREASES A BIT IN THIS TIMEFRAME AS A SHRTWV CURRENTLY OVER WRN CANADA MOVES TO THE UPR GRTLKS RESULTING IN MINOR HEIGHT FALLS AS FAR SOUTH AS OUR CWA. WK CAA SHOULD ALLOW FOR LOWS TO FALL INTO THE M-U60S ACROSS THE AREA. RAIN CHANCES DIMINISH WED-WED NGT AS FRONT CONTS TO SAG SOUTH TO THE OH VALLEY AND SFC HIGH MOVES ESE INTO THE UPR GRTLKS. TEMPS SHOULD FALL BACK CLOSER TO NORMAL WITH HIGHS IN THE L80S AND LOWS IN THE L-M60S. FRONTAL SYSTEM EXPECTED TO LIFT BACK NORTH INTO OUR AREA THU-THU NGT AS SFC HIGH MOVES TO THE MID ATLANTIC/NORTHEAST U.S.. DVLPG SPLIT FLOW CUT-OFF LOW OVER THE WRN U.S. BY MID WEEK IS EXPECTED TO MOVE SLOWLY EAST TO THE CENTRAL PLAINS FRIDAY AND INTO THE MID MS VALLEY BY SUNDAY WHILE SFC BOUNDARY LINGERS OVER THE AREA... ENHANCING TSTM POTENTIAL ACROSS OUR AREA OVER THE LABOR DAY WEEKEND... WHILE TEMPS REMAIN CLOSE TO NORMAL. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 655 AM EDT MON AUG 25 2014 STRATUS/FOG WITH MVFR/IFR CONDITIONS ATTM SHOULD MIX OUT/BURN OFF TO VFR BY MID-MORNING. BKN LINE OF TSRA OVER IA/WI MOVG EAST 20KTS. CONVECTIVE ALLOWING MODELS IN DECENT AGREEMENT THAT THIS CONVECTION WILL GRDLY DIMINISH AS IT MOVES EAST THIS MORNING WHICH SEEMS REASONABLE AS IT MOVES INTO MORE CAPPED AIRMASS OVER OUR AREA. COULD BE SCT REMNANT -SHRA/VFR CIGS BRIEF WIND GUSTS AS REMNANTS MOVE THROUGH SBN TOWARD MIDDAY TOO MUCH UNCERTAINTY REMAINS TO ADD ANYTHING SGFNT TO TAFS. OUTFLOW BOUNDARY FROM THIS DYING CONVECTION COULD SET UP OVER NRN INDIANA AND SUPPORT ISOLATED CONVECTIVE INITIATION AROUND PEAK HEATING BUT CHANCES OF ANYTHING IMPACTING TERMINALS TOO LOW TO MENTION IN TAFS. APCHG CDFNT MAY SPREAD SOME SHRA/TSRA INTO NRN INDIANA LATE TONIGHT. FOR NOW JUST MENTIONED VCSH CLOSEST TO APCHG CDFNT AT SBN... BUT DID ADD MVFR BR TO BOTH TAFS LATE AS BOUNDARY LAYER REMAINS VERY MOIST. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...MARSILI SYNOPSIS...LOTHAMER SHORT TERM...FISHER LONG TERM...JT AVIATION...JT VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
131 PM CDT MON AUG 25 2014 .UPDATE... ISSUED AT 126 PM CDT MON AUG 25 2014 ISOLATED SEVERE STORMS EXPECTED THIS AFTN PORTIONS OF NORTHEAST AND EAST CENTRAL IA INTO NORTHWEST IL WITHIN STRONG THERMAL AND INSTABILITY GRADIENT AHEAD OF WEAK SURFACE LOW MOVING INTO EASTERN IA. MAIN THREAT WILL BE DAMAGING DOWNBURST WINDS AROUND 60 MPH. LOCALLY HEAVY RAINFALL ALSO EXPECTED WITH THE STORMS. HAVE UPDATED THE HWO. IN PROCESS OF SENDING UP A 19Z BALLOON TO BETTER SAMPLE THE ENVIRONMENT. WILL BE SENDING GRID/ZFP/PFM UPDATE SHORTLY. THIS WILL ENCORPORATE CONVECTIVE TRENDS AND ALSO LOWERING OF HIGHS WITH LINGERING COOL POOL OVER PORTIONS OF NORTHEAST IA INTO NORTHWEST IL. && .SYNOPSIS... ISSUED AT 334 AM CDT MON AUG 25 2014 THUNDERSTORMS HAVE DEVELOPED EARLY THIS MORNING ALONG AND AHEAD OF THE SURFACE FRONT EXTENDING ROUGHLY FROM WESTERN LAKE SUPERIOR SW ACROSS WESTERN WI...SW MN...INTO W CENTRAL IA. THIS WAS ALONG AN AXIS OF HIGH THETAE INDICATED BY 850 MB DEWPOINTS OF 14 TO 16 C FROM NORTHEAST KS INTO SW ONTARIO AT 00Z...WITH CONVERGENCE ASSISTED BY 35KT TO 40 KT SW WINDS AT 850 MB. THIS MOISTURE WAS BEING PULLED NORTHWARD BY A STRONG SURFACE AND UPPER LEVEL LOW SEEN ON WV IMAGERY ALONG THE ND/MANITOBA BORDER. AT 3 AM...THE LEADING LINE OF SCATTERED THUNDERSTORMS WAS MOVING INTO BUCHANAN AND BENTON COUNTIES...INTO A VERY HUMID AIRMASS WITH DEWPOINTS IN THE LOWER TO MID 70S AND AIR TEMPERATURES IN THE MID TO UPPER 70S. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 334 AM CDT MON AUG 25 2014 FORECAST CHALLENGES CENTER ON THUNDERSTORMS THIS MORNING AND AGAIN TONIGHT...AND HEAT HEADLINES TODAY AS THE HOT AND HUMID CONDITIONS PERSIST OVER THE REGION. IN THE NEAR TERM...A SEMI-LINEAR MCS WILL LIKELY MOVE ACROSS THE FORECAST AREA MAINLY NORTH OF I-80...DRIVEN BY A WEAK SHORTWAVE FLOW IN THE NW FLOW ALOFT. WHILE NO INDIVIDUAL FORECAST MODEL HAS HAD A GOOD HANDLE ON TRENDS OVERNIGHT...THE HIGH RES WRF AND RAP MODELS APPEAR TO HAVE THE BEST HANDLE ON THE CONVECTION ENTERING THE NORTH. THESE HAVE THE THUNDERSTORMS ADVANCING THROUGH THE NORTH OVER THE NEXT SEVERAL HOURS AND THEN DISSIPATING BY NOON...AND HAVE TRENDED THE FORECAST ACCORDINGLY. THE LATEST RAP IS ALONE WITH DEVELOPING THUNDERSTORMS IN THE HIGH MUCAPE AXIS FURTHER SE...OVER 4000 J/KG...OVER W CENTRAL IL TOWARD SUNRISE...WHICH WHILE NOT IN THE CURRENT FORECAST CANNOT BE ENTIRELY RULED AND WILL WATCH TRENDS CLOSELY. OTHERWISE...THIS SHOULD BE FOLLOWED BY CLEARING SKIES AND A RETURN TO THE HEAT AND HUMIDITY SEEN OVER THE AREA YESTERDAY. DUE TO UNCERTAINTIES IN THE TIMING OF THE DISSIPATING MCS IN THE NORTH AND POSSIBLE DEBRIS CLOUDS FROM STORMS IN THE PLAINS...ALONG WITH 850 MB TEMPERATURES PROGGED ABOUT 1 DEGREE COOLER...HAVE TRENDED HIGHS A DEGREE OR TWO COOLER THAN SUNDAY...WITH UPPER 80S NW TO LOWER 90S CENTRAL AND SOUTH. DEWPOINTS WILL HOLD IN THE LOWER TO MID 70S AND POSSIBLY TOUCH THE UPPER 70S AT TIMES LATE IN THE DAY. THIS COMBINATION WILL SEND HEAT INDEX VALUES TO JUST ABOVE 100 ACROSS THE SOUTH AND WILL KEEP THE PREVIOUS HEAT ADVISORY CONFIGURATION IN PLACE. TONIGHT...THE SETUP WILL BE FAVORABLE FOR ANOTHER MCS AS THE SURFACE FRONT SLOWLY ADVANCES THROUGH THE FORECAST AREA AND MODEST CONVERGENCE OCCURS IN THE 850 MB THETAE AXIS AS IT SHIFTS OVERHEAD. HAVE KEPT LIKELY POPS IN THE NORTH WITH SLIGHT TO LOW END CHANCE POPS IN THE SOUTH TOWARD MORNING. THE MAIN THREAT WILL BE LOCALLY HEAVY RAINFALL. IT WILL BE ANOTHER WARM AND VERY HUMID NIGHT WITH TEMPERATURES AND DEWPOINTS IN THE 70S...EXCEPT IN THE FAR NW...WHERE THE CURRENT FRONTAL TIMING SUGGESTS READINGS LOWERING INTO THE UPPER 60S. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 334 AM CDT MON AUG 25 2014 AN ORGANIZED THUNDERSTORM COMPLEX SHOULD MOVE INTO THE AREA TUESDAY MORNING AND DISSIPATE DURING THE MORNING. BOUNDARIES LEFT OVER FROM THIS COMPLEX COMBINED WITH A WEAK FRONT MOVING THROUGH THE AREA WILL PROVIDE THE FOCUS FOR NEW CONVECTION TUESDAY AFTERNOON AND EVENING. HIGH MOISTURE LEVELS IN THE LOWER ATMOSPHERE MEANS ANY STORM WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL. CLOUD COVER AND RAIN WILL PLAY INTO HOW WARM IT WILL GET ON TUESDAY. THE SOUTHEAST HALF MAY SEE TEMPERATURES AROUND 90 WITH HEAT INDEX READINGS IN THE UPPER 90S TO JUST OVER 100. ANOTHER THUNDERSTORM COMPLEX IS EXPECTED TO DEVELOP IN WESTERN IOWA TUESDAY EVENING AND THEN MOVE MAINLY EAST OVERNIGHT INTO WEDNESDAY MORNING. THIS STORM COMPLEX SHOULD ARRIVE IN THE WESTERN THIRD OF THE CWFA IN THE PRE-DAWN HOURS AND SLOWLY DISSIPATE ACROSS THE AREA WEDNESDAY MORNING. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE FROM THE STORMS DUE TO HIGH MOISTURE LEVELS. LIKE TUESDAY...BOUNDARIES LEFT OVER FROM THE WEDNESDAY STORM COMPLEX WILL PROVIDE THE FOCUS FOR NEW CONVECTION WEDNESDAY AFTERNOON AND EVENING. SIGNALS FROM THE MODELS SUGGEST YET ANOTHER THUNDERSTORM COMPLEX WILL DEVELOP IN WESTERN IOWA WEDNESDAY EVENING AND MOVE GENERALLY EAST OVERNIGHT AND ARRIVE IN THE WESTERN THIRD OF THE AREA IN THE PRE-DAWN HOURS. LOCALLY HEAVY RAINFALL MAY BE POSSIBLE FROM SOME OF THE STRONGER STORMS. THURSDAY ON... THE MODEL CONSENSUS HAS CHANCE POPS IN EACH 12 HOUR PERIOD FROM THURSDAY THROUGH SATURDAY NIGHT. TEMPERATURES SHOULD BE NEAR NORMAL. ON SUNDAY...THE MODEL CONSENSUS HAS SLIGHT CHANCE TO LOW CHANCE POPS. THE LARGE SCALE PICTURE SUGGESTS THE WEATHER PATTERN WILL REMAIN FAIRLY ACTIVE WITH A FRONT STALLED OUT JUST SOUTH OF THE AREA. IT WILL NOT RAIN CONTINUOUSLY THE ENTIRE TIME. THERE WILL BE PERIODS OF DRY WEATHER THAT MAY LAST 6 OR 12 HOURS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 100 PM CDT MON AUG 25 2014 LINE OF SHOWERS AND STORMS EXTENDS JUST SOUTH AND EAST OF DBQ TO CID TERMINAL MOVING EAST. ADDITIONAL DEVELOPMENT EXPECTED NEAR AND NORTH OF I-80 THIS AFTERNOON WITH VARIOUS OUTFLOW BOUNDARIES. FRONT OVER CENTRAL IA TO PROGRESS EAST AND PASS THROUGH THE TERMINALS TONIGHT BRINGING SHIFT IN WINDS TO NORTHERLY. ANTICIPATE SHOWERS AND STORMS TO DEVELOP NORTH OF THE FRONT TONIGHT INTO TUESDAY MORNING WITH THE GREATEST CHANCES RIGHT NOW LOOKING NEAR AND NORTH OF I-80. CONDITIONS IN ANY CONVECTION WILL BE MVFR TO IFR. GUSTY WINDS OF 30+ KTS WILL ALSO BE POSSIBLE WITH THE STRONGER STORMS THIS AFTERNOON. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR DES MOINES-HENRY IA-LEE-LOUISA-MUSCATINE-SCOTT-VAN BUREN. IL...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR BUREAU-HANCOCK- HENDERSON-HENRY IL-MCDONOUGH-MERCER-PUTNAM-ROCK ISLAND- WARREN-WHITESIDE. MO...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR CLARK-SCOTLAND. && $$ UPDATE...05 SYNOPSIS...SHEETS SHORT TERM...SHEETS LONG TERM...08 AVIATION...05
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
108 PM CDT MON AUG 25 2014 .UPDATE... ISSUED AT 1121 AM CDT MON AUG 25 2014 HAVE UPDATED TO BUMP UP POPS AND EXTEND THROUGH THE AFTERNOON AS LOOKING LIKELY TO SEE AT LEAST SCATTERED ACTIVITY PERSIST ALL DAY MOSTLY NORTH OF I-80 WITH MORE ISOLATED OVER SOUTHEAST IA. THIS ACTIVITY WILL BE AIDED BY WEAK SURFACE LOW NORTHEAST OF DES MOINES AND INTERACTING WITH OUTFLOW BOUNDARIES...WITH MAIN BOUNDARY OF NOTE ARCING JUST SOUTH OF I-80. WITH LINGERING CONVECTION AND DEBRIS CLOUDS HAVE TWEAKED HIGHS DOWN OVER PORTIONS OF NORTHEAST IA AND FAR NORTHWEST IL INTO THE MID 80S... BUT WITH DUBUQUE STILL AT 71 DEGS AT 11 AM WOULD NOT BE SURPRISED TO SEE SOME AREAS STRUGGLE TO HIT 80 OR LOWER 80S FAR NORTH. OTHERWISE CURRENT HEAT ADVISORY HEADLINE ON TRACK FROM AROUND QUAD CITIES SOUTH/EAST WITH FEW LOCATIONS ALREADY AT 90 DEGS AND HEAT INDEX READINGS APPROACHING 100. LOOKING FURTHER AHEAD TO TONIGHT AND TUESDAY... COLD FRONT THROUGH NORTHWEST IA MOVING A BIT FASTER THAN MODELS AND LIKELY TO BE LOCATED SOUTH OF THE CWA TUESDAY MORNING. ANTICIPATE POTENTIAL FOR MORE ORGANIZED CONVECTION MOVING ACROSS NORTH 1/3-1/2 LATER TONIGHT INTO TUE AM. IF TRENDS PERSIST THEN GOING FORECAST HIGHS TOMORROW ARE LIKELY TOO WARM...POSSIBLY BY AS MUCH AS 5-10 DEGS NOTING THAT AS WE ARE APPROACHING THE NOON HOUR TEMPS ARE IN THE UPPER 60S TO LOWER 70S IN NORTHWEST IA POST FRONTAL WITH SUNSHINE. THUS WITH CLOUDS AND RAIN COULD EASILY SEE AREAS STUCK IN THE 70S ALL DAY TOMORROW. HAVE NOT MADE CHANGES YET AS STILL EVALUATING MODEL SUITE... AND WILL HAVE MORE ON THIS WITH AFTERNOON DISCO. UPDATED GRIDS/ZFP/PFM HAVE BEEN ISSUED. && .SYNOPSIS... ISSUED AT 334 AM CDT MON AUG 25 2014 THUNDERSTORMS HAVE DEVELOPED EARLY THIS MORNING ALONG AND AHEAD OF THE SURFACE FRONT EXTENDING ROUGHLY FROM WESTERN LAKE SUPERIOR SW ACROSS WESTERN WI...SW MN...INTO W CENTRAL IA. THIS WAS ALONG AN AXIS OF HIGH THETAE INDICATED BY 850 MB DEWPOINTS OF 14 TO 16 C FROM NORTHEAST KS INTO SW ONTARIO AT 00Z...WITH CONVERGENCE ASSISTED BY 35KT TO 40 KT SW WINDS AT 850 MB. THIS MOISTURE WAS BEING PULLED NORTHWARD BY A STRONG SURFACE AND UPPER LEVEL LOW SEEN ON WV IMAGERY ALONG THE ND/MANITOBA BORDER. AT 3 AM...THE LEADING LINE OF SCATTERED THUNDERSTORMS WAS MOVING INTO BUCHANAN AND BENTON COUNTIES...INTO A VERY HUMID AIRMASS WITH DEWPOINTS IN THE LOWER TO MID 70S AND AIR TEMPERATURES IN THE MID TO UPPER 70S. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 334 AM CDT MON AUG 25 2014 FORECAST CHALLENGES CENTER ON THUNDERSTORMS THIS MORNING AND AGAIN TONIGHT...AND HEAT HEADLINES TODAY AS THE HOT AND HUMID CONDITIONS PERSIST OVER THE REGION. IN THE NEAR TERM...A SEMI-LINEAR MCS WILL LIKELY MOVE ACROSS THE FORECAST AREA MAINLY NORTH OF I-80...DRIVEN BY A WEAK SHORTWAVE FLOW IN THE NW FLOW ALOFT. WHILE NO INDIVIDUAL FORECAST MODEL HAS HAD A GOOD HANDLE ON TRENDS OVERNIGHT...THE HIGH RES WRF AND RAP MODELS APPEAR TO HAVE THE BEST HANDLE ON THE CONVECTION ENTERING THE NORTH. THESE HAVE THE THUNDERSTORMS ADVANCING THROUGH THE NORTH OVER THE NEXT SEVERAL HOURS AND THEN DISSIPATING BY NOON...AND HAVE TRENDED THE FORECAST ACCORDINGLY. THE LATEST RAP IS ALONE WITH DEVELOPING THUNDERSTORMS IN THE HIGH MUCAPE AXIS FURTHER SE...OVER 4000 J/KG...OVER W CENTRAL IL TOWARD SUNRISE...WHICH WHILE NOT IN THE CURRENT FORECAST CANNOT BE ENTIRELY RULED AND WILL WATCH TRENDS CLOSELY. OTHERWISE...THIS SHOULD BE FOLLOWED BY CLEARING SKIES AND A RETURN TO THE HEAT AND HUMIDITY SEEN OVER THE AREA YESTERDAY. DUE TO UNCERTAINTIES IN THE TIMING OF THE DISSIPATING MCS IN THE NORTH AND POSSIBLE DEBRIS CLOUDS FROM STORMS IN THE PLAINS...ALONG WITH 850 MB TEMPERATURES PROGGED ABOUT 1 DEGREE COOLER...HAVE TRENDED HIGHS A DEGREE OR TWO COOLER THAN SUNDAY...WITH UPPER 80S NW TO LOWER 90S CENTRAL AND SOUTH. DEWPOINTS WILL HOLD IN THE LOWER TO MID 70S AND POSSIBLY TOUCH THE UPPER 70S AT TIMES LATE IN THE DAY. THIS COMBINATION WILL SEND HEAT INDEX VALUES TO JUST ABOVE 100 ACROSS THE SOUTH AND WILL KEEP THE PREVIOUS HEAT ADVISORY CONFIGURATION IN PLACE. TONIGHT...THE SETUP WILL BE FAVORABLE FOR ANOTHER MCS AS THE SURFACE FRONT SLOWLY ADVANCES THROUGH THE FORECAST AREA AND MODEST CONVERGENCE OCCURS IN THE 850 MB THETAE AXIS AS IT SHIFTS OVERHEAD. HAVE KEPT LIKELY POPS IN THE NORTH WITH SLIGHT TO LOW END CHANCE POPS IN THE SOUTH TOWARD MORNING. THE MAIN THREAT WILL BE LOCALLY HEAVY RAINFALL. IT WILL BE ANOTHER WARM AND VERY HUMID NIGHT WITH TEMPERATURES AND DEWPOINTS IN THE 70S...EXCEPT IN THE FAR NW...WHERE THE CURRENT FRONTAL TIMING SUGGESTS READINGS LOWERING INTO THE UPPER 60S. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 334 AM CDT MON AUG 25 2014 AN ORGANIZED THUNDERSTORM COMPLEX SHOULD MOVE INTO THE AREA TUESDAY MORNING AND DISSIPATE DURING THE MORNING. BOUNDARIES LEFT OVER FROM THIS COMPLEX COMBINED WITH A WEAK FRONT MOVING THROUGH THE AREA WILL PROVIDE THE FOCUS FOR NEW CONVECTION TUESDAY AFTERNOON AND EVENING. HIGH MOISTURE LEVELS IN THE LOWER ATMOSPHERE MEANS ANY STORM WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL. CLOUD COVER AND RAIN WILL PLAY INTO HOW WARM IT WILL GET ON TUESDAY. THE SOUTHEAST HALF MAY SEE TEMPERATURES AROUND 90 WITH HEAT INDEX READINGS IN THE UPPER 90S TO JUST OVER 100. ANOTHER THUNDERSTORM COMPLEX IS EXPECTED TO DEVELOP IN WESTERN IOWA TUESDAY EVENING AND THEN MOVE MAINLY EAST OVERNIGHT INTO WEDNESDAY MORNING. THIS STORM COMPLEX SHOULD ARRIVE IN THE WESTERN THIRD OF THE CWFA IN THE PRE-DAWN HOURS AND SLOWLY DISSIPATE ACROSS THE AREA WEDNESDAY MORNING. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE FROM THE STORMS DUE TO HIGH MOISTURE LEVELS. LIKE TUESDAY...BOUNDARIES LEFT OVER FROM THE WEDNESDAY STORM COMPLEX WILL PROVIDE THE FOCUS FOR NEW CONVECTION WEDNESDAY AFTERNOON AND EVENING. SIGNALS FROM THE MODELS SUGGEST YET ANOTHER THUNDERSTORM COMPLEX WILL DEVELOP IN WESTERN IOWA WEDNESDAY EVENING AND MOVE GENERALLY EAST OVERNIGHT AND ARRIVE IN THE WESTERN THIRD OF THE AREA IN THE PRE-DAWN HOURS. LOCALLY HEAVY RAINFALL MAY BE POSSIBLE FROM SOME OF THE STRONGER STORMS. THURSDAY ON... THE MODEL CONSENSUS HAS CHANCE POPS IN EACH 12 HOUR PERIOD FROM THURSDAY THROUGH SATURDAY NIGHT. TEMPERATURES SHOULD BE NEAR NORMAL. ON SUNDAY...THE MODEL CONSENSUS HAS SLIGHT CHANCE TO LOW CHANCE POPS. THE LARGE SCALE PICTURE SUGGESTS THE WEATHER PATTERN WILL REMAIN FAIRLY ACTIVE WITH A FRONT STALLED OUT JUST SOUTH OF THE AREA. IT WILL NOT RAIN CONTINUOUSLY THE ENTIRE TIME. THERE WILL BE PERIODS OF DRY WEATHER THAT MAY LAST 6 OR 12 HOURS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 100 PM CDT MON AUG 25 2014 LINE OF SHOWERS AND STORMS EXTENDS JUST SOUTH AND EAST OF DBQ TO CID TERMINAL MOVING EAST. ADDITIONAL DEVELOPMENT EXPECTED NEAR AND NORTH OF I-80 THIS AFTERNOON WITH VARIOUS OUTFLOW BOUNDARIES. FRONT OVER CENTRAL IA TO PROGRESS EAST AND PASS THROUGH THE TERMINALS TONIGHT BRINGING SHIFT IN WINDS TO NORTHERLY. ANTICIPATE SHOWERS AND STORMS TO DEVELOP NORTH OF THE FRONT TONIGHT INTO TUESDAY MORNING WITH THE GREATEST CHANCES RIGHT NOW LOOKING NEAR AND NORTH OF I-80. CONDITIONS IN ANY CONVECTION WILL BE MVFR TO IFR. GUSTY WINDS OF 30+ KTS WILL ALSO BE POSSIBLE WITH THE STRONGER STORMS THIS AFTERNOON. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR DES MOINES-HENRY IA-LEE-LOUISA-MUSCATINE-SCOTT-VAN BUREN. IL...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR BUREAU-HANCOCK- HENDERSON-HENRY IL-MCDONOUGH-MERCER-PUTNAM-ROCK ISLAND- WARREN-WHITESIDE. MO...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR CLARK-SCOTLAND. && $$ UPDATE...05 SYNOPSIS...SHEETS SHORT TERM...SHEETS LONG TERM...08 AVIATION...05
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1137 AM CDT MON AUG 25 2014 .UPDATE... ISSUED AT 1121 AM CDT MON AUG 25 2014 HAVE UPDATED TO BUMP UP POPS AND EXTEND THROUGH THE AFTERNOON AS LOOKING LIKELY TO SEE AT LEAST SCATTERED ACTIVITY PERSIST ALL DAY MOSTLY NORTH OF I-80 WITH MORE ISOLATED OVER SOUTHEAST IA. THIS ACTIVITY WILL BE AIDED BY WEAK SURFACE LOW NORTHEAST OF DES MOINES AND INTERACTING WITH OUTFLOW BOUNDARIES...WITH MAIN BOUNDARY OF NOTE ARCING JUST SOUTH OF I-80. WITH LINGERING CONVECTION AND DEBRIS CLOUDS HAVE TWEAKED HIGHS DOWN OVER PORTIONS OF NORTHEAST IA AND FAR NORTHWEST IL INTO THE MID 80S... BUT WITH DUBUQUE STILL AT 71 DEGS AT 11 AM WOULD NOT BE SURPRISED TO SEE SOME AREAS STRUGGLE TO HIT 80 OR LOWER 80S FAR NORTH. OTHERWISE CURRENT HEAT ADVISORY HEADLINE ON TRACK FROM AROUND QUAD CITIES SOUTH/EAST WITH FEW LOCATIONS ALREADY AT 90 DEGS AND HEAT INDEX READINGS APPROACHING 100. LOOKING FURTHER AHEAD TO TONIGHT AND TUESDAY... COLD FRONT THROUGH NORTHWEST IA MOVING A BIT FASTER THAN MODELS AND LIKELY TO BE LOCATED SOUTH OF THE CWA TUESDAY MORNING. ANTICIPATE POTENTIAL FOR MORE ORGANIZED CONVECTION MOVING ACROSS NORTH 1/3-1/2 LATER TONIGHT INTO TUE AM. IF TRENDS PERSIST THEN GOING FORECAST HIGHS TOMORROW ARE LIKELY TOO WARM...POSSIBLY BY AS MUCH AS 5-10 DEGS NOTING THAT AS WE ARE APPROACHING THE NOON HOUR TEMPS ARE IN THE UPPER 60S TO LOWER 70S IN NORTHWEST IA POST FRONTAL WITH SUNSHINE. THUS WITH CLOUDS AND RAIN COULD EASILY SEE AREAS STUCK IN THE 70S ALL DAY TOMORROW. HAVE NOT MADE CHANGES YET AS STILL EVALUATING MODEL SUITE... AND WILL HAVE MORE ON THIS WITH AFTERNOON DISCO. UPDATED GRIDS/ZFP/PFM HAVE BEEN ISSUED. && .SYNOPSIS... ISSUED AT 334 AM CDT MON AUG 25 2014 THUNDERSTORMS HAVE DEVELOPED EARLY THIS MORNING ALONG AND AHEAD OF THE SURFACE FRONT EXTENDING ROUGHLY FROM WESTERN LAKE SUPERIOR SW ACROSS WESTERN WI...SW MN...INTO W CENTRAL IA. THIS WAS ALONG AN AXIS OF HIGH THETAE INDICATED BY 850 MB DEWPOINTS OF 14 TO 16 C FROM NORTHEAST KS INTO SW ONTARIO AT 00Z...WITH CONVERGENCE ASSISTED BY 35KT TO 40 KT SW WINDS AT 850 MB. THIS MOISTURE WAS BEING PULLED NORTHWARD BY A STRONG SURFACE AND UPPER LEVEL LOW SEEN ON WV IMAGERY ALONG THE ND/MANITOBA BORDER. AT 3 AM...THE LEADING LINE OF SCATTERED THUNDERSTORMS WAS MOVING INTO BUCHANAN AND BENTON COUNTIES...INTO A VERY HUMID AIRMASS WITH DEWPOINTS IN THE LOWER TO MID 70S AND AIR TEMPERATURES IN THE MID TO UPPER 70S. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 334 AM CDT MON AUG 25 2014 FORECAST CHALLENGES CENTER ON THUNDERSTORMS THIS MORNING AND AGAIN TONIGHT...AND HEAT HEADLINES TODAY AS THE HOT AND HUMID CONDITIONS PERSIST OVER THE REGION. IN THE NEAR TERM...A SEMI-LINEAR MCS WILL LIKELY MOVE ACROSS THE FORECAST AREA MAINLY NORTH OF I-80...DRIVEN BY A WEAK SHORTWAVE FLOW IN THE NW FLOW ALOFT. WHILE NO INDIVIDUAL FORECAST MODEL HAS HAD A GOOD HANDLE ON TRENDS OVERNIGHT...THE HIGH RES WRF AND RAP MODELS APPEAR TO HAVE THE BEST HANDLE ON THE CONVECTION ENTERING THE NORTH. THESE HAVE THE THUNDERSTORMS ADVANCING THROUGH THE NORTH OVER THE NEXT SEVERAL HOURS AND THEN DISSIPATING BY NOON...AND HAVE TRENDED THE FORECAST ACCORDINGLY. THE LATEST RAP IS ALONE WITH DEVELOPING THUNDERSTORMS IN THE HIGH MUCAPE AXIS FURTHER SE...OVER 4000 J/KG...OVER W CENTRAL IL TOWARD SUNRISE...WHICH WHILE NOT IN THE CURRENT FORECAST CANNOT BE ENTIRELY RULED AND WILL WATCH TRENDS CLOSELY. OTHERWISE...THIS SHOULD BE FOLLOWED BY CLEARING SKIES AND A RETURN TO THE HEAT AND HUMIDITY SEEN OVER THE AREA YESTERDAY. DUE TO UNCERTAINTIES IN THE TIMING OF THE DISSIPATING MCS IN THE NORTH AND POSSIBLE DEBRIS CLOUDS FROM STORMS IN THE PLAINS...ALONG WITH 850 MB TEMPERATURES PROGGED ABOUT 1 DEGREE COOLER...HAVE TRENDED HIGHS A DEGREE OR TWO COOLER THAN SUNDAY...WITH UPPER 80S NW TO LOWER 90S CENTRAL AND SOUTH. DEWPOINTS WILL HOLD IN THE LOWER TO MID 70S AND POSSIBLY TOUCH THE UPPER 70S AT TIMES LATE IN THE DAY. THIS COMBINATION WILL SEND HEAT INDEX VALUES TO JUST ABOVE 100 ACROSS THE SOUTH AND WILL KEEP THE PREVIOUS HEAT ADVISORY CONFIGURATION IN PLACE. TONIGHT...THE SETUP WILL BE FAVORABLE FOR ANOTHER MCS AS THE SURFACE FRONT SLOWLY ADVANCES THROUGH THE FORECAST AREA AND MODEST CONVERGENCE OCCURS IN THE 850 MB THETAE AXIS AS IT SHIFTS OVERHEAD. HAVE KEPT LIKELY POPS IN THE NORTH WITH SLIGHT TO LOW END CHANCE POPS IN THE SOUTH TOWARD MORNING. THE MAIN THREAT WILL BE LOCALLY HEAVY RAINFALL. IT WILL BE ANOTHER WARM AND VERY HUMID NIGHT WITH TEMPERATURES AND DEWPOINTS IN THE 70S...EXCEPT IN THE FAR NW...WHERE THE CURRENT FRONTAL TIMING SUGGESTS READINGS LOWERING INTO THE UPPER 60S. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 334 AM CDT MON AUG 25 2014 AN ORGANIZED THUNDERSTORM COMPLEX SHOULD MOVE INTO THE AREA TUESDAY MORNING AND DISSIPATE DURING THE MORNING. BOUNDARIES LEFT OVER FROM THIS COMPLEX COMBINED WITH A WEAK FRONT MOVING THROUGH THE AREA WILL PROVIDE THE FOCUS FOR NEW CONVECTION TUESDAY AFTERNOON AND EVENING. HIGH MOISTURE LEVELS IN THE LOWER ATMOSPHERE MEANS ANY STORM WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL. CLOUD COVER AND RAIN WILL PLAY INTO HOW WARM IT WILL GET ON TUESDAY. THE SOUTHEAST HALF MAY SEE TEMPERATURES AROUND 90 WITH HEAT INDEX READINGS IN THE UPPER 90S TO JUST OVER 100. ANOTHER THUNDERSTORM COMPLEX IS EXPECTED TO DEVELOP IN WESTERN IOWA TUESDAY EVENING AND THEN MOVE MAINLY EAST OVERNIGHT INTO WEDNESDAY MORNING. THIS STORM COMPLEX SHOULD ARRIVE IN THE WESTERN THIRD OF THE CWFA IN THE PRE-DAWN HOURS AND SLOWLY DISSIPATE ACROSS THE AREA WEDNESDAY MORNING. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE FROM THE STORMS DUE TO HIGH MOISTURE LEVELS. LIKE TUESDAY...BOUNDARIES LEFT OVER FROM THE WEDNESDAY STORM COMPLEX WILL PROVIDE THE FOCUS FOR NEW CONVECTION WEDNESDAY AFTERNOON AND EVENING. SIGNALS FROM THE MODELS SUGGEST YET ANOTHER THUNDERSTORM COMPLEX WILL DEVELOP IN WESTERN IOWA WEDNESDAY EVENING AND MOVE GENERALLY EAST OVERNIGHT AND ARRIVE IN THE WESTERN THIRD OF THE AREA IN THE PRE-DAWN HOURS. LOCALLY HEAVY RAINFALL MAY BE POSSIBLE FROM SOME OF THE STRONGER STORMS. THURSDAY ON... THE MODEL CONSENSUS HAS CHANCE POPS IN EACH 12 HOUR PERIOD FROM THURSDAY THROUGH SATURDAY NIGHT. TEMPERATURES SHOULD BE NEAR NORMAL. ON SUNDAY...THE MODEL CONSENSUS HAS SLIGHT CHANCE TO LOW CHANCE POPS. THE LARGE SCALE PICTURE SUGGESTS THE WEATHER PATTERN WILL REMAIN FAIRLY ACTIVE WITH A FRONT STALLED OUT JUST SOUTH OF THE AREA. IT WILL NOT RAIN CONTINUOUSLY THE ENTIRE TIME. THERE WILL BE PERIODS OF DRY WEATHER THAT MAY LAST 6 OR 12 HOURS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 645 AM CDT MON AUG 25 2014 A SLOW MOVING AXIS OF THUNDERSTORMS OVER NORTHEAST IOWA MAY BRIEFLY IMPACT THE CID AND DBQ TERMINALS EARLY THIS MORNING. FOG AND A FEW AREAS OF LOW CLOUDS WILL IMPACT MOST OF THE TERMINALS WITH PERIODS OF MVFR CONDITIONS UNTIL MID MORNING. OTHERWISE...TODAY WILL BE MAINLY VFR WITH VERY HUMID CONDITIONS. ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED TO MOVE THROUGH EASTERN IOWA AND NORTHWEST ILLINOIS LATE TONIGHT AS A COOL FRONT SLOWLY DROPS SOUTH THROUGH THE AREA. THIS IS MOST LIKELY TO AFFECT THE CID...DBQ AND MLI TERMINALS...WHERE PROB30 GROUPS COVER THE POTENTIAL FOR NOW. ALSO...LIGHT WINDS AND LINGERING LOW LEVEL MOISTURE WILL ALSO LEAD TO MVFR FOG...WHICH IS ALSO INCLUDED FOR THE LATE NIGHT AND EARLY MORNING PERIODS. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR LOUISA-MUSCATINE- SCOTT. HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR DES MOINES-HENRY IA-LEE-VAN BUREN. IL...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR BUREAU-HENRY IL- MERCER-PUTNAM-ROCK ISLAND-WHITESIDE. HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR HANCOCK-HENDERSON- MCDONOUGH-WARREN. MO...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR CLARK-SCOTLAND. && $$ UPDATE...05 SYNOPSIS...SHEETS SHORT TERM...SHEETS LONG TERM...08 AVIATION...SHEETS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
144 PM EDT MON AUG 25 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 535 AM EDT MON AUG 25 2014 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A VIGOROUS LOOKING SHORTWAVE LIFTING THRU ND INTO MANITOBA. ASSOCIATED SFC LOW WAS MOVING INTO SE MANITOBA WITH COLD FRONT EXTENDING THRU FAR ERN MN. AS EXPECTED...SCT TSTMS DEVELOPED AHEAD OF FRONT IN MN LATE YESTERDAY AFTN/EVENING. STORMS THEN ORGANIZED INTO A LINE AND PUSHED E INTO WI/UPPER MI. AS OF 09Z...SHRA/TSTMS EXTENDED FROM NCNTRL LAKE SUPERIOR TO THE HURON MTNS AND CRYSTAL FALLS. CONVECTION HAS HELD TOGETHER FOR MUCH OF THE NIGHT...AND IT HAS ONLY BEEN IN THE LAST HR OR TWO THAT A NOTABLE DIMINISHING TREND HAS BEGUN. NSSL WRF RUN FROM 00Z/24 AUG DID A GREAT JOB AND BETTER THAN ANY OTHER MODEL IN CAPTURING WHAT OCCURRED LAST NIGHT INTO EARLY THIS MORNING... INCLUDING THE DIMINISHING TREND NOW UNDERWAY. WHILE THERE IS STILL SOME INCREASE IN INSTABILITY AHEAD OF CONVECTION PER SPC MESOANALYSIS OF 3HR ML/MUCAPE CHANGE...OVERALL MAGNITUDE OF INSTABILITY IS NOTABLY LESS THAN WHAT WAS SUPPORTING THE CONVECTION EARLIER IN THE NIGHT. DIMINISHING INSTABILITY COMBINED WITH WEAKENING LOW-LEVEL JET WILL CONTINUE TO CAUSE SHRA/TSRA TO WEAKEN AS THEY PUSH E THIS MORNING. QUESTION THEN BECOMES WHETHER THERE WILL BE REDEVELOPMENT ALONG THE MOISTURE AXIS THAT WILL BE SLOWING DOWN. NSSL WRF INCLUDING THE NCEP ARW/NMM WHICH ALSO DID WELL WITH CONVECTION LAST NIGHT SUGGEST LITTLE OR NO ADDITIONAL DEVELOPMENT THIS AFTN. WILL BASICALLY FOLLOW THAT SCENARIO GIVEN A LACK OF MUCH FORCING THIS AFTN. WITH INCREASING SUNSHINE AND 850MB THERMAL RIDGE OVER THE AREA...TODAY SHOULD BE THE WARMEST DAY OF THE WEEK. FCST SOUNDINGS SUPPORT MAX TEMPS AS HIGH AS THE MID/UPPER 80S OVER ROUGHLY THE W HALF. COULD BE WARMER DEPENDING ON HOW QUICKLY CLOUDS SCATTER OUT. E WILL BE COOLER WITH MORE CLOUD COVER AND CONTINUED SOUTHERLY FLOW OFF LAKE MICHIGAN. LOOKS LIKE A SECONDARY COLD FRONT/TROF WILL SWEEP ACROSS THE AREA LATER THIS AFTN/EVENING. AS THE TROF MOVES INTO THE ERN FCST AREA THIS EVENING WHERE MOISTURE/INSTABILITY LINGER...ISOLD SHRA AND PERHAPS A TSRA MAY DEVELOP FROM ERN LAKE SUPERIOR INTO ERN UPPER MI. OTHERWISE...EXPECT A DRY NIGHT...BECOMING COOLER AND LESS HUMID. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 403 AM EDT MON AUG 25 2014 A FAIRLY QUIET AND GENERALLY DRY LONG TERM PERIOD IS IN STORE FOR THE UPPER GREAT LAKES REGION FOR TUESDAY THROUGH THE WEEKEND. THIS TRANSITION WILL OCCUR AS A RESULT OF THE LOW PRESSURE SYSTEM MOVING THROUGH NORTHERN ONTARIO TODAY AND THE ASSOCIATED COLD FRONT THAT PASSES THROUGH. BEHIND THIS LOW AND ASSOCIATED SHORTWAVE...HIGH PRESSURE FROM THE EASTERN DAKOTAS WILL SHIFT EAST OVER THE UPPER GREAT LAKES REGION BY WEDNESDAY WHILE A WEAK UPPER TROUGH SWEEPS THROUGH. IN GENERAL...EXPECT THIS HIGH PRESSURE RIDGE TO SUPPRESS ANY PRECIPITATION TO THE SOUTH OF THE AREA THROUGH THURSDAY. THERE ARE A COUPLE MINOR ITEMS TO NOTE. FIRST...THE SECONDARY SHORTWAVE MOVING THROUGH THE FLOW LATE TUESDAY NIGHT INTO WEDNESDAY MORNING COULD TRY TO SPARK AN ISOLATED SHOWER BUT FEEL THE DRY AIR IN THE LOWER LEVELS ASSOCIATED WITH THE HIGH PRESSURE RIDGE WILL INHIBIT ANY RAIN FROM REACHING THE SURFACE. THUS...WILL JUST SHOW PASSING MID CLOUDS AS THAT WAVE MOVES THROUGH. THE OTHER ITEM IS THE MUCH COOLER AIR BELOW 850MB THAT WILL BE SURGING INTO THE CWA LATE TONIGHT INTO TUESDAY. THIS WILL SETUP A RETURN TO ANOTHER COOLER PERIOD OF HIGH TEMPERATURES OVER THE CWA. WITH THE COLD AIR JUST STARTING TO MOVE IN ON TUESDAY...HIGHS OVER THE CENTRAL/EAST WILL STILL RISE INTO THE UPPER 60S AND LOWER 70S WHILE AREAS OVER THE WEST NEAR LAKE SUPERIOR WILL STAY IN THE MID 60S WITH THE GUSTY WESTERLY WIND OFF THE LAKE. WEDNESDAY WILL BE THE COOLEST DAY (AIDED BY THE MORNING MID CLOUDS LIMITING HEATING AND MODEL AVERAGE 850MB TEMPS AROUND 6-7C)...WITH HIGHS IN THE 60S OVER MOST OF THE CWA. 850MB TEMPS WILL REBOUND SLIGHTLY ON THURSDAY AND ALLOW HIGHS TO BE IN THE UPPER 60S TO AROUND 70 DEGREES. ALONG WITH THAT COOLER AIR ON TUESDAY MORNING...SOME OF THE MODELS ARE INDICATING ENOUGH MOISTURE FOR SOME CLOUDS OVER THE NORTH HALF OF THE CWA. THINK THE COVERAGE WILL BE THE GREATEST DURING THE AFTERNOON HOURS WHEN THE DIURNAL HEATING IS MAXIMIZED AND WILL SHOW PARTLY CLOUDY SKIES DURING THAT TIME. EXPECT MOSTLY CLEAR SKIES FOR THE REST OF THE MIDDLE OF THE WORK WEEK. THE FOCUS THURSDAY NIGHT INTO THE WEEKEND WILL BE THE UPPER DISTURBANCE MOVING OUT OF THE CENTRAL ROCKIES AND INTO THE CENTRAL PLAINS ON WEDNESDAY. THE INITIAL PORTION OF THIS WAVE WILL SHIFT NORTHEAST TOWARDS THE UPPER GREAT LAKES REGION THURSDAY NIGHT AND FRIDAY...WITH MODELS STILL VARYING ON THE NORTHWARD EXTENT OF THE WAVE AND ASSOCIATED PRECIP. CURRENT CONSENSUS IS FOR IT TO BRUSH THE SOUTHEAST THIRD OF THE CWA AND WILL SHOW SLIGHT CHANCES IN THAT AREA. THE SECOND WAVE WILL PUSH THROUGH THE AREA FRIDAY NIGHT INTO SATURDAY AND BRING ANOTHER OPPORTUNITY FOR PRECIPITATION. MODELS ALSO VARYING ON THE LOCATION THIS WAVE...SO WILL FOLLOW A BLEND OF GEM/GFS/ECMWF FOR POPS (SLIGHT OR LOW END CHANCES) WITH THE BEST CHANCES OVER THE SOUTHEAST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 139 PM EDT MON AUG 25 2014 VFR CONDITIONS WILL BE THE RULE THROUGH THE FCST PERIOD. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 535 AM EDT MON AUG 25 2014 FOG MAY BE AN ISSUE OVER PORTIONS OF LAKE SUPERIOR THRU THIS EVENING...MAINLY CNTRL/E AND ESPECIALLY NE GIVEN THE HUMID AIR MASS AND PCPN THAT HAS OCCURRED. PASSAGE OF COLD FRONT AND ARRIVAL OF DRIER AIR TODAY/THIS EVENING WILL THEN WORK TO CLEAR OUT THE FOG FROM W TO E. BEHIND FRONT...WESTERLY WINDS WILL INCREASE TO 15-25KT OVER WRN LAKE SUPERIOR THIS AFTN AND THEN OVER CNTRL LAKE SUPERIOR THIS EVENING. THESE STRONGER WINDS WILL LINGER INTO TUE MORNING...THEN WINDS WILL DIMINISH AS HIGH PRES MOVES CLOSER TO THE AREA. THE HIGH WILL SETTLE INTO THE UPPER LAKES TUE NIGHT THRU THU...BRINGING A PERIOD OF LIGHTER WINDS MOSTLY UNDER 15KT. THE LIGHTER WINDS WILL LINGER INTO FRI DESPITE THE HIGH MOVING TO THE E. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...SRF AVIATION...TITUS MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
329 PM EDT MON AUG 25 2014 .SYNOPSIS... A WARM RIDGE OF HIGH PRESSURE WILL EXPAND EASTWARD ACROSS THE AREA THROUGH LATE WEEK. TROPICAL CYCLONE CRISTOBAL WILL MOVE NORTH AND NORTHEAST...PASSING SEVERAL HUNDRED MILES EAST OF THE CAROLINA COAST TUESDAY NIGHT AND WEDNESDAY. A WARMING TREND WILL DEVELOP MID AND LATE WEEK...WITH MORE TYPICAL LATE SUMMER WEATHER EXPECTED INTO THE WEEKEND. THE RISK FOR SHOWERS AND THUNDERSTORMS WILL BE ON THE INCREASE EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM MONDAY...COOL CANADIAN HIGH PRESSURE CENTERED OVER NEW ENGLAND CONTINUES TO RIDGE DOWN THE COAST...CREATING FALL-LIKE WEATHER ACROSS THE EASTERN CAROLINAS. TEMPS THIS AFTN HAVE STRUGGLED ONLY INTO THE LOW 80S THANKS TO COOL NE FLOW AND WIDESPREAD CLOUD COVER EAST OF I-95. THIS CLOUD COVER IS INCREASING THANKS TO MOIST ADVECTION ON NE FLOW...AND SHOWERS HAVE OVERSPREAD THE COASTAL PORTIONS OF THE CAPE FEAR REGION...AS EXPECTED...AND DEPICTED ON HIGH RES HRRR THROUGH THIS AFTN. THESE SHOWERS DO NOT FEATURE CONSIDERABLE DEPTH...AS COLUMN MOISTENING EXISTS ONLY TO ABOUT 10 KFT /700MB/...ABOVE WHICH VERY DRY AIR EXISTS EMBEDDED WITHIN A SUBSIDENCE INVERSION THANKS TO STRENGTHENING MID-LEVEL RIDGE. THEREFORE...DO NOT EXPECT ANY LIGHTNING THIS AFTN OR EVE...EVEN AS SHOWERS BECOME SLIGHTLY MORE WIDESPREAD ALONG THE EASTERN THIRD OF THE CWA INTO TONIGHT. DRYING WILL OCCUR IN THE LOWER PORTIONS OF THE COLUMN AFTER DARK...AND ANY SHOWER ACTIVITY WILL WANE BY MIDNIGHT. NE WINDS WILL CONTINUE AT 10-15 MPH EVEN AFTER DARK...CONTINUING THE CAA...AND ALLOWING TEMPS TO FALL TO 62-67...COOLEST NORTH...IN A DRY AND CLEAR COLUMN. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 300 PM MONDAY...NE FLOW WILL BEGIN TO ABATE LATER TUE AND TUE NIGHT AS SURFACE HIGH PRESSURE DEVELOPS SOUTHWARD AND IN CLOSER PROXIMITY TO THE EASTERN CAROLINAS. TROPICAL CYCLONE CRISTOBAL WILL BE MOVING TO THE NE...HUGGING 70 DEG WEST LONGITUDE AS IT MOVES NORTH OF OUR LATITUDE TUE NIGHT AND WED. NO DIRECT IMPACTS FROM THE CYCLONE ARE EXPECTED. EXPANSIVE RIDGE ALOFT TO OUR WEST WILL EXPAND EASTWARD AND ACROSS THE AREA WED AND WED NIGHT AND THIS WILL BRING RISING HEIGHTS...INCREASING SUBSIDENCE AND TEMPS MORE TYPICAL OF LATE SUMMER ACROSS THE EASTERN CAROLINAS. WILL NOT INCLUDE ANY POPS THROUGH THE PERIOD. IT IS NOT IMPOSSIBLE THAT A FEW SHOWERS OFFSHORE MANAGE TO BRUSH THE COAST ON TUE...BUT THE RISK IS VERY SMALL. WILL CALL FOR AN ABUNDANCE OF SUNSHINE THROUGH THE PERIOD EXCEPT FOR SOME STRATOCUMULUS WHICH MAY BRUSH THE COAST TUE AND TUE NIGHT. HIGHS WILL BE MAINLY IN THE LOWER TO MID 80S TUE AND IN THE UPPER 80S TO AROUND 90 ON WED. ALONG THE COAST...THE SEABREEZE SHOULD HOLD TEMPS TO THE MID 80S WED AFTERNOON. LOWS WILL BE IN THE LOWER TO MID 60S TUE NIGHT AND MAINLY UPPER 60S TO LOWER 70S WED NIGHT. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 300 PM MONDAY...THE FOCUS ON THE EXTENDED FORECAST NOW SHIFTS TO THE END OF THE PERIOD WHEN A MORE ACTIVE PATTERN SHOULD DEVELOP. MID LEVEL RIDGING WILL DOMINATE CONDITIONS THURSDAY THROUGH SATURDAY . A BROAD MID LEVEL TROUGH WILL BREAK DOWN THE RIDGE SLOWLY SUNDAY AND MONDAY WITH A MORE MOISTURE LADEN SOUTHWEST FLOW DEVELOPING. AT THE SURFACE...HIGH PRESSURE WILL PREVAIL AS WELL. THERE IS A BACKDOOR FRONT STILL IN THE PICTURE FOR LATE THURSDAY AND FRIDAY BUT THIS SHOULD HAVE LITTLE IMPACT ON THE ACTUAL FORECAST OTHER THAN TO BUMP THE TEMPERATURES BACK A COUPLE OF DEGREES. REGARDING POPS...VALUES INCREASE FROM SLIGHT CHANCE SATURDAY TO LOWER CHANCE BY MONDAY. THIS PRIMARILY OF PRECIPITABLE WATER VALUES INCREASING FROM JUST UNDER AN INCH FRIDAY TO WELL ABOVE TWO INCHES MONDAY. TEMPERATURES HOVER AROUND CLIMATOLOGY LEANING TOWARD A DEGREE OR TWO ABOVE FOR THE MOST PART. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 18Z...THE STRATOCU HAS BLOSSOMED OVER THE PAST COUPLE OF HOURS. LOOK FOR AN MVFR STRATOCU CEILING THROUGH MOST OF THE AFTERNOON...WITH PERIODS OF VFR AS THE CU SCATTERS. GUSTY NORTHEAST WINDS WILL BE THE RULE...WITH A FEW BURSTS NEAR 25 KTS ALONG THE IMMEDIATE COAST. THE TROPICAL SYSTEM OFFSHORE WILL NOT BE A FACTOR TODAY...ALTHOUGH IT MAY ENHANCE THE GRADIENT SLIGHTLY. DIMINISHING WINDS THIS EVENING WITH CLEARING SKIES. SOME LIGHT FOG IS POSSIBLE AT THE INLAND TERMINALS...BUT WINDS ALONG THE COAST SHOULD BE HIGH ENOUGH TO PRECLUDE FOG. TUESDAY...CONTINUED NORTHEAST FLOW...NOT AS STRONG AS TODAY HOWEVER. EXTENDED OUTLOOK...EXPECT VFR CONDITIONS THROUGH THE EXTENDED PERIOD. SLIGHT CHANCE OF SHOWERS FOR OUR NORTHERN TERMINALS FRI. INCREASING CHANCES FOR PRECIP SATURDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM MONDAY...HIGH PRESSURE CONTINUES TO RIDGE DOWN FROM NEW ENGLAND JUST INLAND FROM THE WATERS...WHICH WHEN COMBINED WITH THE PRESENCE OF TROPICAL STORM CRISTOBAL NEAR THE BAHAMAS PRODUCES A PINCHED GRADIENT WITH GUSTY NE WINDS. THESE WINDS HAVE BEEN SUSTAINED AT 15-20 KTS...WITH GUSTS ABOVE 25 KTS NEAR THE 20 NM BOUNDARY AND OVER THE NORTHERN COASTAL WATERS. THIS IS EXPECTED TO CONTINUE WITH LITTLE FLUCTUATION THROUGH THE PERIOD. SE SWELL FROM CRISTOBAL HAS AMPLIFIED AND REACHED THE WATERS...AND IS SHOWING UP AS 2-3FT/10SEC AT THE BUOYS. THIS SWELL...ALONG WITH A 5-7 FT NE WIND WAVE...ARE TOGETHER IN THE WAVE SPECTRUM PRODUCING SIGNIFICANT SEAS OF 4-7 FT THIS AFTN...WHICH WILL PERSIST INTO TUESDAY MORNING. THE ONGOING SMALL CRAFT ADVISORY REMAINS UNCHANGED FOR THIS PERIOD TO ACCOUNT FOR THE HAZARDOUS MARINE CONDITIONS. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 300 PM MONDAY...THE PRESSURE DIFFERENCE BETWEEN HIGH PRESSURE TO THE NORTH AND A TROPICAL CYCLONE WELL OFF THE SOUTHEAST COAST WILL KEEP A RATHER TIGHT PRESSURE GRADIENT ACROSS THE WATERS INTO TUE NIGHT. THE GRADIENT WILL RELAX SIGNIFICANTLY WED AND WED NIGHT AS HIGH PRESSURE DOMINATES. WIND SPEEDS WILL BE UP TO 20 KT TUE... BECOMING 10 KT OR LESS BY WED AFTERNOON. THE DIRECTION WILL BE NE TUE...BUT WILL SLOWLY BACK TO NNE OR N TUE NIGHT. THE DIRECTION WILL BECOME MORE SOUTHERLY DURING WED AS THE SEABREEZE CIRCULATION DOMINATES. SEAS WILL BE UP TO 4 TO 6 FT TUE...SUBSIDING TO 2 TO 4 FT BY WED AFTERNOON. A 10 TO 12 SECOND SE SWELL IS EXPECTED THROUGH THE PERIOD. LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 300 PM MONDAY...VERY LIGHT WIND FIELDS THROUGH THE PERIOD AS HIGH PRESSURE WILL PREVAIL AT ALL LEVELS OF THE ATMOSPHERE. DIRECTIONS WILL GENERALLY BE FROM THE SOUTH WITH THE SEA BREEZE BACKING THE DIRECTION EACH AFTERNOON CLOSER TO THE COAST. ALL SPEEDS ARE WITHIN A COUPLE OF KNOTS EITHER SIDE OF TEN KNOTS. BENIGN SEAS WILL PREVAIL THROUGH THE PERIOD WITH 1-3 FEET. && .TIDES/COASTAL FLOODING... AS OF 300 PM MONDAY...RIDGE OF HIGH PRESSURE CENTERED OVER NEW ENGLAND CONTINUES TO RIDGE DOWN THE COAST...WITH THE AXIS JUST INLAND FROM THE SHORE. THIS LEAVES THE WATERS SANDWICHED BETWEEN THE HIGH...AND TROPICAL STORM CRISTOBAL NEAR THE BAHAMAS...PRODUCING PERSISTENT AND STRONG NE WINDS LOCALLY. THESE NE WINDS ARE PUSHING WATER TOWARDS SHORE...AND LOCAL TIDAL ANOMALIES ARE RUNNING +1 TO +2 FT TODAY. THESE ANOMALIES WILL RISE ON TOP OF A NEW-MOON ENHANCED ASTRONOMICAL HIGH TIDE THIS EVENING...TO PRODUCE MINOR COASTAL FLOODING ALONG ALL EAST FACING BEACHES. HIGH TIDE IS AROUND 8PM THIS EVENING...AND MINOR COASTAL FLOOD THRESHOLDS MAY BE EXCEEDED FOR ABOUT A 1 HR WINDOW BOTH SIDES OF HIGH TIDE. A COASTAL FLOOD ADVISORY HAS AGAIN BEEN ISSUED FOR THE EAST FACING BEACHES OF THE CAPE FEAR REGION...AS WELL AS THE ENTIRE GRAND STRAND OF SOUTH CAROLINA. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...COASTAL FLOOD ADVISORY FROM 7 PM TO 10 PM EDT THIS EVENING FOR SCZ054-056. NC...COASTAL FLOOD ADVISORY FROM 7 PM TO 10 PM EDT THIS EVENING FOR NCZ106-108. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT TUESDAY FOR AMZ250-252-254- 256. && $$ NEAR TERM...JDW SHORT TERM...RJD LONG TERM...SHK AVIATION...JDW/DL TIDES/COASTAL FLOODING...JDW
AREA FORECAST DISCUSSION
NWS BISMARCK ND
325 PM CDT MON AUG 25 2014 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 323 PM CDT MON AUG 25 2014 THE MAIN FORECAST ISSUES IN THE LONG TERM PERIOD WILL BE TEMPERATURES TONIGHT AND PRECIPITATION CHANCES SOUTHWEST AND SOUTH CENTRAL LATE TONIGHT AND TUESDAY. THE PESKY UPPER LOW IS NOW LIFTING OUT OF THE AREA. ONE LAST TRAILING VORT COMBINED WITH ANOTHER APPROACHING SHORTWAVE IS KEEPING A FEW SHOWERS OVER NORTHEAST MONTANA AND NORTHWEST NORTH DAKOTA. THE 18Z HRRR SHOWS THE SHOWERS HANGING ON THROUGH 00Z. WILL MENTION SOME SCATTED SPRINKLES NORTHWEST LATE THIS AFTERNOON. THE APPROACHING SHORTWAVE...IN COMBINATION WITH AN STRENGTHENING UPPER LEVEL JET WILL PRODUCE INCREASING CLOUDS AND EVENTUALLY A SWATH OF LIGHT PRECIPITATION...MOVING INTO THE SOUTHWEST LATE TONIGHT AND SPREADING ACROSS THE SOUTHWEST AND SOUTH CENTRAL ON TUESDAY. THE INCREASING CLOUDS SHOULD HELP TEMPER THE MERCURY DROP LATE TONIGHT OVER THE SOUTHWEST. BUT WITH DECREASING CLOUDS...AND DIMINISHING WINDS...MOST AREAS ARE EXPECTED TO FALL INTO THE LOWER TO MIDDLE 40S. WOULD NOT BE SURPRISED TO SEE A FEW LOWS INTO THE UPPER 30S. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 323 PM CDT MON AUG 25 2014 A BROAD POSITIVELY TILTED TROUGH IS FORECAST TO HAVE MOVED EAST OF THE FORECAST AREA BY TUESDAY NIGHT...WITH DRY CONDITIONS EXPECTED TUESDAY NIGHT. A WARMING TREND ALONG WITH DRY CONDITIONS ARE EXPECTED TO CONTINUE WEDNESDAY THROUGH FRIDAY AS WEAK UPPER LEVEL RIDGING BUILDS OVER THE NORTHERN PLAINS. NEAR NORMAL HIGHS ARE FORECAST BY FRIDAY. THE UPPER RIDGE IS PROGGED TO BREAK DOWN SOMEWHAT BY FRIDAY NIGHT...AND WEAK WAVES IN THE UPPER FLOW ALOFT WILL GENERATE CHANCES FOR THUNDERSTORMS EACH PERIOD FRIDAY NIGHT THROUGH MONDAY. NEAR NORMAL TEMPERATURES ARE EXPECTED TO CONTINUE THROUGH THE WEEKEND AND INTO MONDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 323 PM CDT MON AUG 25 2014 MVFR TO LOW VFR CEILINGS ARE EXPECTED TO ALL LIFT TO LOW VFR AROUND 22 UTC. NORTHWEST SURFACE FLOW WILL DIMINISH FROM WEST TO EAST AFTER 21 UTC. VFR CONDITIONS ARE EXPECTED ACROSS TAF SITES TONIGHT AND TUESDAY MORNING. && .HYDROLOGY... ISSUED AT 323 PM CDT MON AUG 25 2014 HEAVY RAINFALL IN THE PAST COUPLE OF DAYS HAVE CAUSED OVERLAND FLOODING...AS WELL AS RISES IN CREEKS...RIVERS...AND STREAMS IN PARTS OF SOUTH CENTRAL NORTH DAKOTA - ESPECIALLY WEST OF THE MISSOURI RIVER. SIOUX...GRANT...AND WESTERN MORTON COUNTIES SAW LARGE AREAS OF 2 TO 4 INCHES OF RAIN. AN AREAL FLOOD WARNING REMAINS IN EFFECT FOR PARTS OF WESTERN MORTON COUNTY AND PARTS OF NORTHERN GRANT COUNTY. THESE AREAS INCLUDE THE BIG MUDDY CREEK BETWEEN GLEN ULLIN AND ALMONT...SOUTHWARD TO HEIL...CARSON...AND LARK. THESE AREAS CONTAIN SMALL CREEKS AND STREAMS THAT ARE TRIBUTARIES TO THE HEART RIVER. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...TWH LONG TERM...JV AVIATION...TWH HYDROLOGY...TWH
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
410 PM EDT MON AUG 25 2014 .SYNOPSIS... TEMPERATURES WILL CONTINUE TO WARM ACROSS THE REGION WITH A STRONG UPPER LEVEL RIDGE ALOFT. HIGH PRESSURE AT THE SURFACE WILL REMAIN ALONG THE EAST COAST ON TUESDAY WHILE LOW PRESSURE OVER ONTARIO PASSES NORTH OF THE GREAT LAKES. THE ASSOCIATED COLD FRONT WILL PUSH SOUTH ACROSS THE AREA LATE TUESDAY NIGHT INTO WEDNESDAY...FOLLOWED BY HIGH PRESSURE BUILDING EAST ACROSS THE GREAT LAKES ON THURSDAY. && .NEAR TERM /THROUGH TUESDAY NIGHT/... THE FORECAST AREA REMAINS BENEATH A STRONG UPPER LEVEL RIDGE ALOFT WITH SURFACE HIGH PRESSURE TO THE EAST AND A TROUGH MOVING INTO THE WESTERN GREAT LAKES. THERE IS ABOUT A 10 DEGREE SPREAD IN BOTH TEMPERATURES AND DEWPOINTS ACROSS THE AREA LATE THIS AFTERNOON AS A VERY WARM AND HUMID AIRMASS SPREADS INTO NW OHIO WHILE SEASONABLE CONDITIONS REMAIN IN WESTERN PENNSYLVANIA. MAIN FORECAST CONCERN FOR TONIGHT REVOLVES AROUND THE EVOLUTION OF THE MCS MOVING INTO NW INDIANA. A VERY UNSTABLE ENVIRONMENT IS IN PLACE ACROSS NRN ILLINOIS AND WESTERN INDIANA...WITH INSTABILITY DECREASING INTO WESTERN OHIO WHERE ML CAPES ARE CLOSER TO 1000-1500 J/KG. STORM MOTION HAS BEEN TOWARDS THE SOUTH SOUTHEAST TOWARDS THE BETTER INSTABILITY OVER THE LAST HOUR OR TWO WITH GENERALLY WEAK FLOW ALOFT. 850-300MB FLOW IS WESTERLY IN WESTERN INDIANA THEN BECOMES MORE NORTHWESTERLY TO THE EAST. THE LATEST RUN OF THE HRRR ALSO SHOWS THIS ACTIVITY TRACKING TO THE SOUTHEAST AND HAVE ADDED A CHANCE OF THUNDERSTORMS FOR THIS EVENING INTO NW OHIO. OUT OF AHEAD OF THIS COMPLEX WE ARE ALSO SEEING SOME SMALL SHOWERS POPPING UP IN EXTREME NW OHIO BUT THESE WILL LIKELY STRUGGLE WITH THE CAP STILL IN PLACE. THE SEVERE WEATHER THREAT REMAINS SOMEWHAT UNCLEAR AT THIS TIME. ONLY ONE WARNING HAS BEEN ISSUED IN NRN INDIANA AND THERE HAVE BEEN NO REPORTS OF SEVERE WEATHER AS OF 345 PM EDT. SHEAR SHOULD BE A LIMITING FACTOR AND THE LATEST RADAR IMAGERY SUGGESTS THE GUST FRONT MAY BE OUTPACING THE DEEPER CONVECTION. THIS WOULD LIMIT THE SEVERE POTENTIAL AS WE HEAD INTO THIS EVENING. OTHERWISE THERE IS ALSO A CHANCE OF SHOWERS AND THUNDERSTORMS SINKING SOUTH ACROSS LOWER MICHIGAN OVERNIGHT TOWARDS NW OHIO AND WILL KEEP A LOW POP IN THE FORECAST FOR OVERNIGHT. SEVERE WEATHER IS NOT EXPECTED LATER TONIGHT. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... SHOWERS AND THUNDERSTORMS SHOULD GENERALLY BE LOCATED NORTH OF THE AREA TO START THE DAY ON TUESDAY. INSTABILITY AND DEEP MOISTURE AXIS WILL CONTINUE TO INCREASE OVER THE AREA WITH A WEST SOUTHWESTERLY FLOW AHEAD OF THE APPROACHING FRONT. TEMPERATURES WILL APPROACH 90 DEGREES IN NW OHIO WITH DEWPOINTS CLIMBING INTO THE LOW 70S. THIS WILL PUSH HEAT INDEX VALUES TO AROUND 95 DEGREES WHICH WILL BE NEAR THE HOTTEST CONDITIONS EXPERIENCED ALL SUMMER TOWARDS THE I-75 CORRIDOR. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FILL IN AS THE FRONT SINKS SOUTH TOWARDS NW OHIO DURING THE AFTERNOON. THE FRONT IS EXPECTED TO BE FAIRLY SLOW MOVING DURING THE AFTERNOON...DEPENDING ON THE EVOLUTION OF THE CONVECTION. A SERIES OF SHORTWAVES WILL ROUND THE RIDGE AND PUSH THE FRONTAL BOUNDARY SOUTHWARD OVERNIGHT. NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED ON LAKE ERIE TUESDAY NIGHT...SINKING SOUTH ACROSS THE EASTERN CWA OVERNIGHT. GIVEN THE VERY MOIST AIRMASS AND MOVEMENT ALONG THE FRONT...VERY HEAVY RAIN WILL BE POSSIBLE WITH THUNDERSTORMS ON TUESDAY NIGHT AND WILL HAVE TO CONSIDER THE POTENTIAL FOR LOCALIZED FLOODING. THE FRONT STILL LOOKS TO PUSH SOUTH ACROSS THE AREA ON WEDNESDAY MORNING SO WILL CONTINUE WITH SHOWERS AND THUNDERSTORMS ENDING DURING THE MORNING. THE TIMING OF THE CONVECTION DURING THE TUESDAY NIGHT INTO WEDNESDAY MORNING IS NOT REAL FAVORABLE FOR SEVERE THUNDERSTORMS. LOWERED HIGHS ON WEDNESDAY SEVERAL MORE DEGREES WITH BACK INTO THE MID 70S TO LOWER 80S. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT ON WEDNESDAY NIGHT AND THURSDAY. && .LONG TERM /FRIDAY THROUGH MONDAY/... I THINK THE KEY FOR THE LONG TERM PORTION OF THE FORECAST IS THE PROGRESSION OF THE TROUGH EASTWARD FROM THE ROCKIES. MOST OF THE MORE RELIABLE GUIDANCE SHOWS THE TROUGH APPROACHING BY SUNDAY BUT THERE IS STILL A LOT OF UNCERTAINTY. IN THE MEAN TIME...THE STALLED SURFACE FRONT WILL RETURN NORTH AS A WARM FRONT ON FRIDAY. NOT SURE HOW MUCH COVERAGE OF SHOWERS AND THUNDERSTORMS THERE MIGHT BE...THE GFS SEEMS TYPICALLY TOO STRONG AND TOO FAR NORTH WITH THE SURFACE WAVE. AND SOME OF THE OTHER MODELS HAVE THE CONVECTIVE FEEDBACK LOOK. WILL HAVE A CHANCE OF SHOWERS AND STORMS FRIDAY INTO SATURDAY. IT WOULD SEEM THAT THE WARM SECTOR SHOULD MAKE PROGRESS NORTHWARD INTO THE AREA BY THE WEEKEND BUT WILL NOT GO ALL OUT ON TEMPS YET FOR SATURDAY UNTIL A LITTLE MORE CONFIDENT OF THE TIMING. THE FORECAST WILL HAVE HIGHS IN THE LOWER AND MID 80S ON SATURDAY BUT TEMPS COULD TAKE A RUN TOWARD 90F. AS MENTIONED BEFORE...THE THUNDERSTORMS SHOULD INCREASE ON SUNDAY BUT WILL ONLY GO FOR A 50 PERCENT CHANCE FOR NOW...NOT YET COMFORTABLE FORECASTING "LIKELY" GIVEN THE UNCERTAINTY. THE FRONT MAY BE THROUGH THE AREA ON MONDAY LABOR DAY AND PERHAPS THE SHOWER THREAT WILL MOVE EAST WITH SOMEWHAT COOLER TEMPS. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... A RELATIVELY SMALL CUMULUS FIELD WAS SPREADING OUT ACROSS NORTH CENTRAL OHIO BUT THE CUMULUS SHOULD SCATTER OUT DURING THE MID TO LATE AFTERNOON AND EVENTUALLY EVAPORATE THIS EVENING. HIGH CLOUDS WILL SPREAD ACROSS THE AREA FROM THE THUNDERSTORMS IN MICHIGAN AND SCATTERED TO BROKEN ALTOCUMULUS WILL PROBABLY DEVELOP IN THE EARLY MORNING HOURS ON TUESDAY. THERE IS AN OUTSIDE CHANCE THAT SHOWERS OR THUNDERSTORMS COULD SNEAK INTO NORTHWEST OHIO TUESDAY MORNING BUT WILL NOT INCLUDE IT IN THE TAF FORECASTS AT THIS TIME. OUTLOOK...NON VFR POSSIBLE TUESDAY EVENING INTO WEDNESDAY MORNING IN SHOWERS AND THUNDERSTORMS. && .MARINE... THE SOUTHEAST FLOW ON THE LAKE WILL BE LOCALLY ONSHORE EARLY THIS EVENING OTHERWISE IT WILL CONTINUE TO VEER MORE FROM THE SOUTH AND THEN SOUTHWEST AHEAD OF THE NEXT COLD FRONT. THE TIMING ON THE FRONT STILL SEEMS TO BE LATE TUESDAY NIGHT OR EARLY WEDNESDAY. THE FLOW SHOULD BECOME NORTHERLY SOON AFTER THE FRONTAL PASSAGE. THE GRADIENT AHEAD OF THE FRONT AND BEHIND THE FRONT IS LIGHT TO MODERATE BUT EVEN A MODERATE NORTH WIND MAY APPROACH SMALL CRAFT ADVISORY CONDITIONS LATER WEDNESDAY INTO WEDNESDAY NIGHT. THE HIGH PRESSURE SYSTEM IS EXPECTED TO CROSS EASTERN CANADA SO THE FLOW SHOULD VEER MORE EASTERLY BY THURSDAY NIGHT AND SOUTHEAST AND SOUTH AGAIN BY THE WEEKEND. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KEC NEAR TERM...KEC SHORT TERM...KEC LONG TERM...KOSARIK AVIATION...KOSARIK MARINE...KOSARIK
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
333 PM CDT MON AUG 25 2014 .DISCUSSION... IT IS A QUIET AND WARM DAY ACROSS THE REGION AS WE AWAIT OUR NEXT WEATHER SYSTEMS. THE UPPER LEVEL RIDGE THAT HAS BEEN DOMINATING OUR WEATHER PATTERN THE LAST FEW DAYS HAS MOVED TO OUR NORTHEAST AND WILL REMAIN CENTERED TO OUR NORTHEAST AS A TUTT LOW IN THE NORTHERN GULF OF MEXICO MOVES WEST TOWARDS THE TEXAS COAST. THIS FEATURE IS SCHEDULED BY MOST OF THE MODELS TO APPROACH THE TEXAS COAST TUESDAY AFTERNOON BUT THE RAP IS INDICATING A MUCH SLOWER MOVEMENT OF THE TUTT. IN ADDITION...THE TRACK OF THE TUTT APPEARS TO BE SLIGHTLY FURTHER SOUTH THAN PREVIOUS MODEL RUNS. DESPITE THIS...RICH TROPICAL MOISTURE WILL STILL MOVE WEST AND NORTHWEST INTO THE REGION STARTING TUESDAY AND THE UPPER LEVEL RIDGE WILL WEAKEN SOME OVER THE REGION. THIS WILL ALLOW ISOLATED TO SCATTERED CONVECTION TO DEVELOP ACROSS THE REGION TOMORROW AFTERNOON. COVERAGE IS NOT EXPECTED TO BE VERY HIGH SO KEPT RAIN CHANCES AT 20 PERCENT ACROSS THE EAST AND SOUTHEAST WITH JUST AN ISOLATED MENTION ELSEWHERE. GUSTY WINDS...LIGHTNING AND BRIEF HEAVY RAIN WILL BE POSSIBLE WITH ANY THUNDERSTORMS. ON WEDNESDAY...WE WILL REMAIN IN A TRANSITION PERIOD AS AN UPPER LEVEL TROUGH MOVES ACROSS THE WESTERN CONUS. THIS TROUGH WILL HELP TO FURTHER PUSH THE RIDGE TO THE EAST. ISOLATED TO SCATTERED CONVECTION WILL BE POSSIBLE ON WEDNESDAY AS RICH ATMOSPHERIC MOISTURE REMAINS IN PLACE. ON THURSDAY THE UPPER LEVEL TROUGH MOVES INTO THE PLAINS. PREVIOUS MODEL RUNS WERE IN DECENT AGREEMENT ON THE SPEED OF THE TROUGH BUT THE LATEST RUNS HAVE AGAIN STARTED TO DIVERGE FROM EACH OTHER. AS THE TROUGH APPROACHES FROM THE WEST ON THURSDAY...ISOLATED TO SCATTERED CONVECTION WILL AGAIN OCCUR IN THE AFTERNOON AND EVENING HOURS WITH BETTER COVERAGE LIKELY IN THE SOUTHEAST WHERE THE MOISTURE WILL BE HIGHER...AND IN THE NORTHWEST CLOSER TO THE APPROACHING TROUGH. OUR BEST RAIN CHANCES WILL BE FRIDAY AND/OR SATURDAY DEPENDING ON THE SPEED OF THE TROUGH. THE GFS IS THE FASTEST OF THE EXTENDED MODELS WITH THE ECMWF THE SLOWEST OF THE MODELS. BECAUSE OF THE DISCREPANCIES...HAVE LINGERED POPS INTO SUNDAY AND ENDED THEM FROM WEST TO EAST THROUGH THE DAY. IF THE GFS IS REALIZED AND THE TROUGH IS OFF TO OUR NORTHEAST BY SATURDAY NIGHT...THE RAIN CHANCES WILL END EARLIER. BENEFICIAL RAIN IS POSSIBLE WITH THIS SYSTEM DEPENDING ON THE SPEED OF THE UPPER LEVEL TROUGH BUT SOME LOCATIONS WILL BENEFIT FROM THE RAIN MORE THAN OTHERS. WITH THE PATTERN CHANGE THIS WEEK...TEMPERATURES THROUGH MIDWEEK WILL BE SLIGHTLY ABOVE NORMAL BUT BELOW 100 DEGREES. FOR THE LATTER HALF OF THE WEEK...EXPECT NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES. 82/JLD && .AVIATION... /ISSUED 1257 PM CDT MON AUG 25 2014/ FOR THE 18Z TAFS...VFR CONDITIONS ARE EXPECTED THROUGH THE VALID FORECAST PERIOD. THUNDERSTORM CHANCES AROUND AREA TAF SITES TOMORROW AFTERNOON IS THE PRIMARY AVIATION WEATHER CONCERN. IN THE SHORT TERM...LIGHT SOUTHWESTERLY WINDS ARE EXPECTED TO BECOME SOUTHEASTERLY BY 20Z. FORECAST SOUNDINGS AND MORNING AIRCRAFT RAOBS INDICATED THAT HEATING TODAY WAS UNLIKELY TO BREAK THE CAP IN PLACE OVER THE REGION. THEREFORE DRY CONDITIONS ARE EXPECTED OVER THE NEXT 18 HOURS. BY TOMORROW AFTERNOON...18-24 HOURS OF SOUTHEASTERLY WINDS SHOULD BRING DEEPER MOISTURE INTO THE REGION WHICH WILL ALLOW FOR ISOLATED TO SCATTERED THUNDERSTORMS TO DEVELOP ACROSS THE REGION DURING THE PEAK HEATING HOURS OF THE DAY TOMORROW AFTERNOON. WENT AHEAD WITH A MENTION OF VCTS AT THE END OF THE DFW TAF TO ACCOUNT FOR THIS POSSIBILITY. CONFIDENCE IS HIGH THAT A STORM WILL DIRECTLY IMPACT A TAF SITE...BUT MOST FORECAST SOUNDINGS INDICATED LITTLE CAP IN PLACE OVER THE REGION BY 21Z TOMORROW. CAVANAUGH && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 79 98 77 98 77 / 5 10 10 10 10 WACO, TX 75 98 74 98 74 / 5 10 10 10 10 PARIS, TX 73 95 72 95 71 / 5 20 20 10 10 DENTON, TX 76 97 74 97 73 / 5 10 10 10 10 MCKINNEY, TX 75 96 74 96 72 / 5 10 10 10 10 DALLAS, TX 80 98 78 98 77 / 5 10 10 10 10 TERRELL, TX 77 98 76 97 74 / 5 20 20 10 10 CORSICANA, TX 77 98 76 97 74 / 5 20 20 20 20 TEMPLE, TX 74 99 74 98 73 / 5 10 10 20 20 MINERAL WELLS, TX 74 98 73 98 74 / 10 10 10 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 69/82
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1257 PM CDT MON AUG 25 2014 .AVIATION... FOR THE 18Z TAFS...VFR CONDITIONS ARE EXPECTED THROUGH THE VALID FORECAST PERIOD. THUNDERSTORM CHANCES AROUND AREA TAF SITES TOMORROW AFTERNOON IS THE PRIMARY AVIATION WEATHER CONCERN. IN THE SHORT TERM...LIGHT SOUTHWESTERLY WINDS ARE EXPECTED TO BECOME SOUTHEASTERLY BY 20Z. FORECAST SOUNDINGS AND MORNING AIRCRAFT RAOBS INDICATED THAT HEATING TODAY WAS UNLIKELY TO BREAK THE CAP IN PLACE OVER THE REGION. THEREFORE DRY CONDITIONS ARE EXPECTED OVER THE NEXT 18 HOURS. BY TOMORROW AFTERNOON...18-24 HOURS OF SOUTHEASTERLY WINDS SHOULD BRING DEEPER MOISTURE INTO THE REGION WHICH WILL ALLOW FOR ISOLATED TO SCATTERED THUNDERSTORMS TO DEVELOP ACROSS THE REGION DURING THE PEAK HEATING HOURS OF THE DAY TOMORROW AFTERNOON. WENT AHEAD WITH A MENTION OF VCTS AT THE END OF THE DFW TAF TO ACCOUNT FOR THIS POSSIBILITY. CONFIDENCE IS HIGH THAT A STORM WILL DIRECTLY IMPACT A TAF SITE...BUT MOST FORECAST SOUNDINGS INDICATED LITTLE CAP IN PLACE OVER THE REGION BY 21Z TOMORROW. CAVANAUGH && .UPDATE... THE UPPER LEVEL RIDGE WILL CONTINUE TO CONTROL THE WEATHER RESULTING IN A HOT DAY ACROSS THE REGION UNDER CLEAR OR MOSTLY CLEAR SKIES WITH LIGHT WINDS. FORECAST MODELS INDICATE THE PRECIPITATION THAT CONTINUES IN THE TEXAS PANHANDLE IS OCCURRING WITHIN A SHEAR AXIS THAT WILL CONTINUE TO SLIDE EAST-NORTHEAST TODAY. THE HRRR DEVELOPS ISOLATED CONVECTION IN OUR FAR NORTHWESTERN COUNTIES THIS AFTERNOON...NEAR THIS SHEAR AXIS BUT AS OF NOW IT IS THE ONLY MODEL DEVELOPING CONVECTION IN THE AREA. FORECAST MODEL SOUNDINGS IN THAT AREA INDICATE A DRY ATMOSPHERE IN PLACE THROUGH THE REGION AND AM NOT INCLINED TO ADD POPS AT THIS TIME BUT WILL INCLUDE SILENT 10 POPS AND WATCH TRENDS THROUGH THE AFTERNOON HOURS. OTHERWISE...THE FORECAST WAS ON TRACK AND NO SIGNIFICANT CHANGES WERE NEEDED FOR THE UPDATE. 82/JLD && .PREV DISCUSSION... /ISSUED 347 AM CDT MON AUG 25 2014/ THE UPPER LEVEL HIGH THAT BROUGHT US OUR LATEST STRETCH OF HOT AND DRY WEATHER WILL BEGIN TO WEAKEN AND BACK OFF TO THE NORTHEAST TODAY AND TOMORROW. SURFACE WINDS WILL BE FAIRLY LIGHT TODAY WHICH MEANS HIGH TEMPS WILL BE A LITTLE WARMER THAN YESTERDAY. ALSO LOW TEMPS IN NON-URBAN AREAS WILL COOL OFF A LITTLE MORE TONIGHT COMPLIMENTS OF THE LIGHT WINDS AND CLEAR SKIES. THE LATEST WATER VAPOR LOOP SHOWS THE WEAK TUTT LOW THAT WE HAVE BEEN TRACKING FOR THE LAST FEW DAYS HAS MOVED WEST INTO THE CENTRAL GULF. MEANWHILE A NON-TROPICAL SURFACE LOW CENTER HAS DEVELOPED NEAR THE MISSISSIPPI RIVER DELTA ALONG AN OLD FRONTAL BOUNDARY THAT HAS PUSHED INTO THE NORTHEAST GULF OF MEXICO. THE TUTT AND SURFACE LOW WILL CONTINUE ON A WESTERLY TRACK...WITH THE UPPER TUTT AXIS CROSSING OUR CWA TUESDAY AND CAUSING PRECIPITABLE WATER VALUES TO SURGE TO NEAR 2 INCHES. THE BETTER CHANCES OF RAIN WILL BE OVER THE EASTERN AND SOUTHEASTERN ZONES TUESDAY AFTERNOON AND EVENING WHERE LIFT/MOISTURE ARE GREATER. HOWEVER WILL MENTION ISOLATED SHOWERS/STORMS IN THE FORECAST ALONG AND WEST OF THE I-35 CORRIDOR AS THERE IS SOME SPATTERING OF QPF FROM SEVERAL MODELS THERE AS WELL. LOW LEVEL WINDS WILL BECOME EASTERLY DURING THE DAY TUESDAY AND WE WILL SEE THE BEGINNING OF A SLIGHT COOLING TREND IN HIGH TEMPS AS LOW LEVEL THICKNESSES DECREASE FROM EAST TO WEST. THE SURFACE LOW WILL HANG OUT IN THE WESTERN GULF INTO THURSDAY... AND WHILE TROPICAL DEVELOPMENT OF THIS FEATURE IS NOT LIKELY...IT WILL TEND TO CONSOLIDATE THE BETTER MOISTURE/CONVECTION OVER THE WESTERN GULF AND SOUTH TEXAS. NORTH TEXAS WILL SEE DRY ADVECTION DUE TO PERSISTENT EASTERLY FETCH IN THE LOW LEVELS AROUND THIS CYCLONE...AND THUS HAVE LOWERED POPS TO 10 PERCENT. WILL RETAIN A MENTION OF AFTERNOON/EVENING ISOLATED CONVECTION IN THE WORDED FORECAST AS MOISTURE AND INSTABILITY STILL SHOULD BE SUFFICIENT FOR SUCH ON WEDNESDAY. MOISTURE DIMINISHES EVEN MORE INTO THURSDAY...AND THUS WILL SHOW A DRY FORECAST EXCEPT FOR THE SOUTHEAST ZONES. MOST OF THE RAIN ACTIVITY WILL REMAIN TO OUR SOUTH AND EAST WHERE PRECIPITABLE WATERS STAY ABOVE 2 INCHES WITH THE GULF LOW PRESSURE SYSTEM. FORTUNATELY...AFTER SEVERAL DAYS OF MODEL DISAGREEMENT...GUIDANCE HAS COME INTO EXCELLENT AGREEMENT REGARDING THE TRACK AND SPEED OF A LONGWAVE TROUGH THAT MOVES EAST ACROSS THE CONUS. AS THIS SYSTEM APPROACHES THE REGION THURSDAY AND FRIDAY...IT WILL DRAW THE RICH GULF MOISTURE NORTHWESTWARD INTO THE REGION. RAIN CHANCES WILL INCREASE FRIDAY AND INTO SATURDAY AS UPPER LEVEL FORCING FROM THE TROUGH INTERACTS WITH THIS HIGH MOISTURE AND INSTABILITY. LIFT FROM THE UPPER TROUGH LOOKS FAIRLY STRONG FOR THE TIME OF THE YEAR...AND SHEAR MAY BE MARGINALLY SUFFICIENT FOR MULTICELL CONVECTIVE MODES WITH A THREAT FOR SOME SEVERE STORMS. HIGH PRECIPITABLE WATER AND INSTABILITY WILL CERTAINLY SUPPORT A LOCALLY HEAVY RAIN THREAT. HAVE BUMPED UP POPS TO 30 PERCENT FOR MOST OF THE AREA FRIDAY NIGHT AND SATURDAY...AND THESE POPS WILL PROBABLY BE RAISED FURTHER AS CONFIDENCE IN THE TIMING OF THE UPPER TROUGH INCREASES. RAIN CHANCES SHOULD DIMINISH SUNDAY FROM WEST TO EAST WITH THE PASSAGE OF THE UPPER TROUGH AXIS. TEMPERATURES WILL COOL INTO THE LOW TO MID 90S FRIDAY AND SATURDAY DUE TO THE INCREASED CLOUDS AND MOISTURE. TEMPS REBOUND ONLY SLIGHTLY SUNDAY AND MONDAY AS GEOPOTENTIAL HEIGHTS REMAIN DEPRESSED IN THE WAKE OF THE UPPER TROUGH. TR.92 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 101 78 99 78 98 / 5 5 10 10 10 WACO, TX 101 75 99 74 98 / 5 5 10 20 10 PARIS, TX 97 75 95 73 95 / 5 5 20 20 10 DENTON, TX 100 75 98 74 97 / 5 5 10 10 10 MCKINNEY, TX 99 75 97 74 96 / 5 5 10 10 10 DALLAS, TX 100 80 99 79 98 / 5 5 10 10 10 TERRELL, TX 100 77 98 75 97 / 5 5 20 20 10 CORSICANA, TX 100 76 98 75 97 / 5 5 20 20 20 TEMPLE, TX 100 74 99 73 98 / 5 5 10 20 20 MINERAL WELLS, TX 102 74 100 73 98 / 10 10 5 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ /
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1148 AM CDT MON AUG 25 2014 .UPDATE... THE UPPER LEVEL RIDGE WILL CONTINUE TO CONTROL THE WEATHER RESULTING IN A HOT DAY ACROSS THE REGION UNDER CLEAR OR MOSTLY CLEAR SKIES WITH LIGHT WINDS. FORECAST MODELS INDICATE THE PRECIPITATION THAT CONTINUES IN THE TEXAS PANHANDLE IS OCCURRING WITHIN A SHEAR AXIS THAT WILL CONTINUE TO SLIDE EAST-NORTHEAST TODAY. THE HRRR DEVELOPS ISOLATED CONVECTION IN OUR FAR NORTHWESTERN COUNTIES THIS AFTERNOON...NEAR THIS SHEAR AXIS BUT AS OF NOW IT IS THE ONLY MODEL DEVELOPING CONVECTION IN THE AREA. FORECAST MODEL SOUNDINGS IN THAT AREA INDICATE A DRY ATMOSPHERE IN PLACE THROUGH THE REGION AND AM NOT INCLINED TO ADD POPS AT THIS TIME BUT WILL INCLUDE SILENT 10 POPS AND WATCH TRENDS THROUGH THE AFTERNOON HOURS. OTHERWISE...THE FORECAST WAS ON TRACK AND NO SIGNIFICANT CHANGES WERE NEEDED FOR THE UPDATE. 82/JLD && .AVIATION... /ISSUED 638 AM CDT MON AUG 25 2014/ CONCERNS...NONE. SURFACE HIGH PRESSURE TO THE EAST-NORTHEAST WILL BE LOOSENING ITS GRIP ON THE REGION WHILE A SURFACE TROUGH REMAINS WILL REMAIN ACROSS THE PANHANDLE AND WEST TEXAS REGION. THIS WILL CAUSE WINDS TO BACK TO THE SOUTHEAST LATE THIS AFTERNOON AND REMAIN SO OVERNIGHT. COULD SEE A SOUTHWEST COMPONENT FOR A FEW HOURS THIS MORNING. ALL TERMINALS WILL BE VFR WITH SOUTHERLY WINDS LESS THAN 10 KNOTS TODAY AND SOUTHEASTERLY WINDS LESS THAN 8 KNOTS TONIGHT. 75 && .PREV DISCUSSION... /ISSUED 347 AM CDT MON AUG 25 2014/ THE UPPER LEVEL HIGH THAT BROUGHT US OUR LATEST STRETCH OF HOT AND DRY WEATHER WILL BEGIN TO WEAKEN AND BACK OFF TO THE NORTHEAST TODAY AND TOMORROW. SURFACE WINDS WILL BE FAIRLY LIGHT TODAY WHICH MEANS HIGH TEMPS WILL BE A LITTLE WARMER THAN YESTERDAY. ALSO LOW TEMPS IN NON-URBAN AREAS WILL COOL OFF A LITTLE MORE TONIGHT COMPLIMENTS OF THE LIGHT WINDS AND CLEAR SKIES. THE LATEST WATER VAPOR LOOP SHOWS THE WEAK TUTT LOW THAT WE HAVE BEEN TRACKING FOR THE LAST FEW DAYS HAS MOVED WEST INTO THE CENTRAL GULF. MEANWHILE A NON-TROPICAL SURFACE LOW CENTER HAS DEVELOPED NEAR THE MISSISSIPPI RIVER DELTA ALONG AN OLD FRONTAL BOUNDARY THAT HAS PUSHED INTO THE NORTHEAST GULF OF MEXICO. THE TUTT AND SURFACE LOW WILL CONTINUE ON A WESTERLY TRACK...WITH THE UPPER TUTT AXIS CROSSING OUR CWA TUESDAY AND CAUSING PRECIPITABLE WATER VALUES TO SURGE TO NEAR 2 INCHES. THE BETTER CHANCES OF RAIN WILL BE OVER THE EASTERN AND SOUTHEASTERN ZONES TUESDAY AFTERNOON AND EVENING WHERE LIFT/MOISTURE ARE GREATER. HOWEVER WILL MENTION ISOLATED SHOWERS/STORMS IN THE FORECAST ALONG AND WEST OF THE I-35 CORRIDOR AS THERE IS SOME SPATTERING OF QPF FROM SEVERAL MODELS THERE AS WELL. LOW LEVEL WINDS WILL BECOME EASTERLY DURING THE DAY TUESDAY AND WE WILL SEE THE BEGINNING OF A SLIGHT COOLING TREND IN HIGH TEMPS AS LOW LEVEL THICKNESSES DECREASE FROM EAST TO WEST. THE SURFACE LOW WILL HANG OUT IN THE WESTERN GULF INTO THURSDAY... AND WHILE TROPICAL DEVELOPMENT OF THIS FEATURE IS NOT LIKELY...IT WILL TEND TO CONSOLIDATE THE BETTER MOISTURE/CONVECTION OVER THE WESTERN GULF AND SOUTH TEXAS. NORTH TEXAS WILL SEE DRY ADVECTION DUE TO PERSISTENT EASTERLY FETCH IN THE LOW LEVELS AROUND THIS CYCLONE...AND THUS HAVE LOWERED POPS TO 10 PERCENT. WILL RETAIN A MENTION OF AFTERNOON/EVENING ISOLATED CONVECTION IN THE WORDED FORECAST AS MOISTURE AND INSTABILITY STILL SHOULD BE SUFFICIENT FOR SUCH ON WEDNESDAY. MOISTURE DIMINISHES EVEN MORE INTO THURSDAY...AND THUS WILL SHOW A DRY FORECAST EXCEPT FOR THE SOUTHEAST ZONES. MOST OF THE RAIN ACTIVITY WILL REMAIN TO OUR SOUTH AND EAST WHERE PRECIPITABLE WATERS STAY ABOVE 2 INCHES WITH THE GULF LOW PRESSURE SYSTEM. FORTUNATELY...AFTER SEVERAL DAYS OF MODEL DISAGREEMENT...GUIDANCE HAS COME INTO EXCELLENT AGREEMENT REGARDING THE TRACK AND SPEED OF A LONGWAVE TROUGH THAT MOVES EAST ACROSS THE CONUS. AS THIS SYSTEM APPROACHES THE REGION THURSDAY AND FRIDAY...IT WILL DRAW THE RICH GULF MOISTURE NORTHWESTWARD INTO THE REGION. RAIN CHANCES WILL INCREASE FRIDAY AND INTO SATURDAY AS UPPER LEVEL FORCING FROM THE TROUGH INTERACTS WITH THIS HIGH MOISTURE AND INSTABILITY. LIFT FROM THE UPPER TROUGH LOOKS FAIRLY STRONG FOR THE TIME OF THE YEAR...AND SHEAR MAY BE MARGINALLY SUFFICIENT FOR MULTICELL CONVECTIVE MODES WITH A THREAT FOR SOME SEVERE STORMS. HIGH PRECIPITABLE WATER AND INSTABILITY WILL CERTAINLY SUPPORT A LOCALLY HEAVY RAIN THREAT. HAVE BUMPED UP POPS TO 30 PERCENT FOR MOST OF THE AREA FRIDAY NIGHT AND SATURDAY...AND THESE POPS WILL PROBABLY BE RAISED FURTHER AS CONFIDENCE IN THE TIMING OF THE UPPER TROUGH INCREASES. RAIN CHANCES SHOULD DIMINISH SUNDAY FROM WEST TO EAST WITH THE PASSAGE OF THE UPPER TROUGH AXIS. TEMPERATURES WILL COOL INTO THE LOW TO MID 90S FRIDAY AND SATURDAY DUE TO THE INCREASED CLOUDS AND MOISTURE. TEMPS REBOUND ONLY SLIGHTLY SUNDAY AND MONDAY AS GEOPOTENTIAL HEIGHTS REMAIN DEPRESSED IN THE WAKE OF THE UPPER TROUGH. TR.92 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 101 78 99 78 98 / 5 5 10 10 10 WACO, TX 101 75 99 74 98 / 5 5 10 20 10 PARIS, TX 97 75 95 73 95 / 5 5 20 20 10 DENTON, TX 100 75 98 74 97 / 5 5 10 10 10 MCKINNEY, TX 99 75 97 74 96 / 5 5 10 10 10 DALLAS, TX 100 80 99 79 98 / 5 5 10 10 10 TERRELL, TX 100 77 98 75 97 / 5 5 20 20 10 CORSICANA, TX 100 76 98 75 97 / 5 5 20 20 20 TEMPLE, TX 100 74 99 73 98 / 5 5 10 20 20 MINERAL WELLS, TX 102 74 100 73 98 / 10 10 5 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 69/82
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
254 PM CDT MON AUG 25 2014 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT) ISSUED AT 254 PM CDT MON AUG 25 2014 MAIN FORECAST CONCERN IS WITH THE RAIN CHANCES THROUGH THE PERIOD. SURFACE ANALYSIS THIS AFTERNOON SUGGESTS THE COLD FRONT IS MAKING SLOW EASTWARD PROGRESS THROUGH THE WESTERN SECTIONS OF THE FORECAST AREA. DEW POINTS REMAIN IN THE 70S AHEAD OF THE FRONT BUT THEN DROP OFF INTO THE 50S ACROSS CENTRAL MINNESOTA. LOCAL AND REGIONAL RADARS SHOW THE LINE OF STORMS THAT MOVED THROUGH OVERNIGHT EXTEND FROM SOUTHEAST WISCONSIN INTO EASTERN IOWA AND ARE STARTING TO INTENSIFY AGAIN. THE EXPECTATION THROUGH THE REST OF THE AFTERNOON INTO THE EVENING IS THAT THE ONGOING ACTIVITY WILL CONTINUE TO MOVE AWAY FROM THE AREA AS THE FRONT PROGRESSES THROUGH THE FORECAST AREA. SOME ADDITIONAL ACTIVITY FORMING ON THE WESTERN PART OF THE FRONT OVER THE MISSOURI RIVER VALLEY. THE 25.17Z HRRR SUGGESTS THIS WILL TRACK INTO CENTRAL IOWA BEFORE DIMINISHING. HOWEVER...CONFIDENCE IN THIS MODEL OUTPUT IS NOT THAT HIGH. OUTPUT FROM THE 25.15Z HOP-WRF DOES SUGGEST THIS MAY SURVIVE AND COME ACROSS NORTHEAST IOWA THIS EVENING AND WILL SHOW SOME SMALL RAIN CHANCES FOR THIS. ADDITIONAL CONVECTION SHOULD FORM OVERNIGHT ALONG THE COLD FRONT AS A SHORT WAVE TROUGH COMES OUT OF THE CENTRAL ROCKIES. THE MOISTURE TRANSPORT INTO THE FRONT DOES NOT LOOK TO BE ALL THAT STRONG TONIGHT AND AS CANADIAN HIGH PRESSURE BUILDS IN FROM THE NORTH...THE BULK OF THE RAIN TONIGHT SHOULD REMAIN OVER CENTRAL AND SOUTHERN IOWA. THE HIGH WILL GRADUALLY MOVE EAST-SOUTHEAST ACROSS THE UPPER MIDWEST AND BE OVER THE U.P. OF MICHIGAN BY WEDNESDAY NIGHT. THIS IS EXPECTED TO KEEP THE FRONT FAR ENOUGH SOUTH THAT MOST OF THE CONVECTION ALONG IT FROM TUESDAY THROUGH WEDNESDAY SHOULD STAY TO THE SOUTH. CANNOT RULE OUT THE SOUTHERN PARTS OF THE FORECAST AREA GETTING CAUGHT ON THE NORTH EDGE OF THE COMPLEXES THAT FORM ALONG THE FRONT AND WILL SHOW SOME 20 TO 40 PERCENT RAIN CHANCES FOR THIS SCENARIO. BY WEDNESDAY NIGHT THE HIGH WILL START TO MOVE FARTHER OFF TO THE EAST ALLOWING DEEPER MOISTURE TO START RETURNING TO THE AREA. THIS MOISTURE RETURN SHOULD OCCUR AHEAD OF STRONGER SHORT WAVE TROUGH EJECTING NORTHEAST OUT OF THE CENTRAL ROCKIES. THIS WAVE SHOULD BRING AT LEAST SOME WEAK PV ADVECTION IN THE 500-300 MB LAYER INTO THE AREA ALONG WITH 1 TO 3 UBAR/S OF UP GLIDE ON THE 310K ISENTROPIC SURFACE. SHOULD SEE ACTIVITY DEVELOP TO THE WEST/SOUTHWEST OF THE AREA WEDNESDAY EVENING AND THEN MOVE IN DURING THE OVERNIGHT HOURS. .LONG TERM...(THURSDAY THROUGH MONDAY) ISSUED AT 254 PM CDT MON AUG 25 2014 THE SHORT WAVE TROUGH THAT COMES OUT WEDNESDAY NIGHT WILL TRACK ACROSS THE UPPER MIDWEST THURSDAY AND SHOULD BE THE FIRST OF SEVERAL WAVES AS THE MEAN LONG WAVE TROUGH SLOWLY MOVES EAST AS IT BUMPS INTO THE RIDGING OVER THE EASTERN CONUS. DIFFERENCES BETWEEN THE 25.12Z ECMWF AND GFS ON HOW FAST THE LONG WAVE TROUGH WILL MOVE EAST WITH THE ECMWF BEING SLOWER THAN THE GFS. ALSO DIFFERENCES ON HOW MUCH RIDGING WILL OCCUR BEHIND THIS LONG WAVE TROUGH AHEAD OF THE NEXT SYSTEM MOVING ONTO THE PACIFIC NORTHWEST COAST. WITH SUCH DIFFERENCES BETWEEN THE MODELS PLAN TO STAY WITH THE MODEL CONSENSUS GRIDS AND SHOW RAIN CHANCES THROUGH MUCH OF THE PERIOD WITH THE HIGHEST CHANCES THURSDAY AND THURSDAY NIGHT AS THE FIRST SHORT WAVE TROUGH COMES ACROSS THE REGION. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1258 PM CDT MON AUG 25 2014 VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. A COLD FRONT WILL PUSH SOUTH AND EAST OF THE TAF SITES LATE THIS AFTERNOON INTO THIS EVENING. THE FRONT LOOKS TO STALL OVER PORTIONS OF CENTRAL OR NORTHERN IOWA INTO CENTRAL ILLINOIS AND WILL BE THE FOCUS FOR SHOWERS AND STORMS. THIS ACTIVITY WILL REMAIN SOUTH OF THE TAF SITES THE NEXT FEW DAYS AS HIGH PRESSURE BUILDS IN. PLAN ON MID TO HIGH CLOUDS PUSHING NORTH OF THE SHOWER AND STORM ACTIVITY THIS EVENING INTO THE OVERNIGHT HOURS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...04 LONG TERM...04 AVIATION...WETENKAMP
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND TUESDAY ISSUED AT 242 PM CDT MON AUG 25 2014 THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW AN OCCLUDED LOW PRESSURE OVER LAKE WINNIPEG AND A COLD FRONT SLICING ACROSS WESTERN LAKE SUPERIOR AND WISCONSIN FROM ABOUT HAYWARD TO LA CROSSE. AHEAD OF THE FRONT...THE ATMOSPHERE HAS BEEN VERY SLOW TO DESTABILIZE AS TEMPERATURES REMAIN IN THE UPPER 70S TO LOWER 80S. STARTING TO SEE SOME MIDDLE 80S POP UP OVER WEST-CENTRAL WISCONSIN WHERE ML CAPES ARE RISING TO ABOUT 1200 J/KG. STILL SEVERAL MORE HOURS OF HEATING TO GO THOUGH ESPECIALLY OVER CENTRAL AND EASTERN WISCONSIN WHERE CONVECTIVE DEBRIS CONTINUES TO HOVER OVERHEAD. BECAUSE OF THE SLOWER HEATING SO FAR...HAVE REDUCED THE CHANCES OF SHOWERS AND THUNDERSTORMS FOR THE REST OF THE AFTERNOON INTO THE ISOLATED RANGE AFTER 21Z. AS THE FRONT MOVES THROUGH...SHOWER AND THUNDERSTORM CHANCES ARE THE MAIN FORECAST CONCERN. TONIGHT...THE COLD FRONT WILL SLOWLY SLIDE SOUTHEAST ACROSS NORTHEAST AND EAST-CENTRAL WISCONSIN DURING THE EVENING BEFORE EXITING THE LAKE MICHIGAN SHORELINE AROUND 06-08Z. AHEAD OF THE FRONT...WILL LEAVE AN ISOLATED MENTION OF SHOWERS AND THUNDERSTORMS OVER NORTHEAST AND EAST-CENTRAL WISCONSIN UNTIL THE FRONT CLEARS THE AREA. IF TEMPS CAN RISE INTO MIDDLE 80S AHEAD OF THE FRONT...WHICH SEEMS REASONABLE...ANY STORMS THAT DEVELOP COULD BECOME STRONG AND PRODUCE STRONG GUSTY WINDS AND HAIL. HOWEVER...THE MESO MODELS ARE EXTREMELY BEARISH IN PREDICTING THUNDERSTORMS THIS AFTERNOON. AND WITH THE SLOW DESTABILIZATION SO FAR TODAY...HAVE LOWERED THE CHANCES OF STORMS. AS INSTABILITY IS LOST THIS EVENING...INTENSITY OF ANY STORMS SHOULD WANE QUICKLY BY MID-EVENING. COOLER AND DRIER AIR WILL GRADUALLY MAKE INROADS ACROSS THE FORECAST AREA BEHIND THE FRONT...BUT WARM AND MUGGY CONDITIONS SHOULD HANG ON FOR MUCH OF THE NIGHT ACROSS THE EAST. LOWS RANGING FROM THE MIDDLE 50S NORTH TO MIDDLE 60S SOUTHEAST. TUESDAY...THE COLD FRONT WILL CONTINUE TO MOVE SOUTH OVER SOUTHEAST WISCONSIN AND NORTHERN ILLINOIS WHILE CANADIAN HIGH PRESSURE MOVES INTO THE NORTHWEST GREAT LAKES. MOST AREAS WILL SEE A GOOD DEAL OF SUNSHINE...THOUGH CU MAY BE A LITTLE MORE PREVALENT OVER N-C WISCONSIN WHILE HIGH CLOUDS WILL LIKELY REMAIN OVERHEAD OVER CENTRAL AND EAST-CENTRAL WISCONSIN. TEMPS AND HUMIDITY LEVELS WILL BE SIGNIFICANTLY LOWER THAN TODAYS READINGS...AND WILL GO WITH HIGHS IN THE LOWER 70S NORTH TO THE UPPER 70S SOUTH. .LONG TERM...TUESDAY NIGHT THROUGH MONDAY ISSUED AT 242 PM CDT MON AUG 25 2014 CONTINUED WITH SAME TRENDS OF FORECAST AS MODELS CONTINUE TO SHOW A PROGRESSIVE NORTHERN STREAM ALONG THE U.S. AND CANADIAN BORDER THRU THE END OF THE WEEK. WILL BE DEALING WITH ENERGY MOVING THROUGH THE NORTHERN STREAM AND WEAK CUT OFF TROF MEANDERING OUT OF THE WEST...THROUGH THE CENTRAL PLAINS. TUE NIGHT THROUGH THU...EARLY IN PERIOD...SHORT WAVE TO MOVE OUT OF NORTHERN PLAINS INTO WESTERN LAKES. AT THE SURFACE DRIER AIR WITH SURFACE HIGH IN PLACE OVER NORTHERN HALF OF WI WITH FRONT SHOVED SOUTH INTO NORTHERN IL. HAVE CONTINUED DRY FORECAST FROM PREVIOUS SHIFT...BUT PAST TWO RUNS OF EC SHOWING LIGHT PCPN BREAKING OUT OVER THE NORTH ALONG 850 FRONT. LATER SHIFT CAN REVIEW BUT FOR NOW KEPT DRY. MEANDERING TROF BEGINS TO MOVE INTO CENTRAL PLAINS BY THU. OLD FRONT TO BEGIN TO MAKE WAY NORTH. MODELS SUGGEST CONVECTIVE COMPLEX DEVELOPING MN/WESTERN WI AS 850 FLOW INCREASES OVER FRONT. GFS AND NAM FURTHER NORTH WITH COMPLEX THAN CANADIAN AND EC. SREF TENDING TO SUPPORT FURTHER SOUTH LOOK. HAVE STAYED CLOSE TO PREVIOUS FORECAST WITH CHANCE POPS DURING DAY ON THU. UNSETTLED WEATHER TO THEN PERSIST THROUGH THE END OF THE FORECAST AS MORE ENERGY MOVES THROUGH CANADA. TEMPERATURES EXPECTED TO RUN NEAR OR A BIT BELOW NORMAL THROUGH MUCH OF THE PERIOD. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1143 AM CDT MON AUG 25 2014 SHOWERS AND STORMS HAVE EXITED TO THE SOUTH AND EAST BUT A COLD FRONT STILL RESIDES OVER WESTERN WISCONSIN AND WILL SLOWLY MOVE EAST OVER THE COURSE OF THE AFTERNOON. ISOLATED OR SCATTERED SHOWERS AND STORMS ARE POSSIBLE AHEAD OF THE FRONT OVER NORTHEAST WISCONSIN ONCE THE ATMOSPHERE DESTABILIZES BY LATER THIS AFTERNOON. DUE TO UNCERTAINTY IN THE COVERAGE OF THESE STORMS...HAVE LEFT OUT A MENTION AT THE NORTHEAST WISCONSIN TAF SITES. THE FRONT WILL CLEAR EAST-CENTRAL WISCONSIN LATE IN THE EVENING OR EARLY OVERNIGHT...ENDING THE SHOWER AND STORM THREAT. DRIER AIR WILL BUILD INTO THE REGION LATE TONIGHT AND TUESDAY...WHICH SHOULD LEAD TO GOOD FLYING CONDITIONS. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TE AVIATION.......MPC