Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 261824 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 224 PM EDT SAT JUL 26 2014 .SYNOPSIS... UPPER LEVEL LOW WITH DISTURBANCES IN THE FLOW THROUGH TONIGHT. COLD FRONT WITH STRONG STORMS SUNDAY. LINGERING CONVECTION IN THE UPPER LEVEL LOW THROUGH MONDAY. COOLER AIRMASS SETTLES IN PLACE THROUGH MID WEEK. && .NEAR TERM /THROUGH TONIGHT/... 1030 AM UPDATE... WATCHING ONE FAIRLY SMALL BUT STOUT AREA OF SHOWERS AND THUNDERSTORMS OVER SOUTHEAST INDIANA AND EXTREME SOUTHWEST OHIO AT THIS TIME. IF IT HOLDS TOGETHER IT WOULD MAKE IT INTO OUR KENTUCKY COUNTIES BY AROUND 16Z-17Z. HI-RES CONVECTIVE MODELS ARE INSISTENT UPON THIS ACTIVITY DISSIPATING BY THE TIME IT REACHES THAT AREA...YET CLOUD HEIGHTS/TEMPS MAINTAINING THEMSELVES AT THIS POINT. ADDED SLIGHT/LOW CHANCE POPS...AS WELL AS ACCOMPANYING SKY COVER...FOR THE KENTUCKY COUNTIES AND EXTREME SOUTH-CENTRAL OHIO COUNTIES FOR A FEW HOURS EARLY THIS AFTERNOON TO ACCOUNT FOR THAT POTENTIAL. OTHERWISE...FORECAST FOR REMAINDER OF AREA IS ON TRACK. 6 AM UPDATE...NO SIGNIFICANT CHANGE. PREVIOUS DISCUSSION... MODELS ARE IN GOOD AGREEMENT ON A VIGOROUS SHORT WAVE APPROACHING FROM THE WEST TONIGHT...WITH A WELL DEFINED WARM FRONT FOR THIS TIME OF YEAR LIFTING NORTH AND EAST TOWARD OUR AREA. GIVEN THE STRENGTH OF THE DYNAMICS AND A MODERATE 850 MB SOUTHWESTERLY JET FEEDING WARM AND QUITE MOIST AIR NORTHWARD...THE MODELS TARGET THE BEST COMBINATION OF THESE PARAMETERS RIGHT ACROSS OUR AREA...MAINLY LATER TONIGHT IN THE FORM OF AN MCS. WITH HPC AND SPC ALSO TARGETING OUR AREA WITH A RISK FOR BOTH SEVERE STORMS AND EXCESSIVE RAINFALL...HAVE TO GO WITH THIS SCENARIO. THIS BRINGS CAT POPS FROM THE WEST AND NORTHWEST ACROSS OUR AREA TONIGHT...AGAIN MAINLY AFTER MIDNIGHT. HOWEVER...OF SOME CONCERN IS THE EFFECTS OF A STILL NORTHWESTERLY COMPONENT OF THE 1000-5000 MB THICKNESS FIELDS...WHICH MAY PULL THE ANTICIPATED COMPLEX FORMING WELL UPSTREAM LATER TODAY MORE SOUTHEASTWARD INTO KENTUCKY. AT THIS POINT THOUGH...FROM ALL THAT IS MENTIONED ABOVE...CONFIDENCE IS NOT HIGH ENOUGH TO DEVIATE FROM GUIDANCE. WILL MENTION THESE CONCERNS IN THE HAZARDOUS WEATHER PRODUCT FOR NOW...UNTIL WE GET MORE CONFIDENCE IN THE EVOLUTION OF THINGS TODAY BEFORE ANY WATCHES ARE CONSIDERED. OH YES...ABOUT TODAY. TODAY WILL BE THE TRANSITION TO THE SETUP FOR TONIGHT. SURFACE HIGH PRESSURE SHIFTING FARTHER OFF TO THE EAST WILL ALLOW STRONG WARM AND MOIST ADVECTION ON INCREASING SOUTHWESTERLY FLOW. EARLY MORNING UPPER DISTURBANCE WITH THE WIDESPREAD MID CLOUDS WILL LIFT OUT BY MID MORNING...BEING REPLACED BY A SCATTERED CU FIELD THIS AFTERNOON WITH LACK OF UPPER DISTURBANCES. THUS...KEEPING THINGS DRY BUT MUCH WARMER AND MORE HUMID TODAY UNDER A GOOD DEAL OF SUNSHINE. GOING ON THE WARMER SIDE OF GUIDANCE WITH HIGHS APPROACHING 90 DEGREES. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... BEST PLACE TO START WITH THIS FORECAST IS THE MODERATE RISK FROM SPC IN THE MIDDLE OHIO VALLEY AND CENTRAL APPALACHIANS FOR SUNDAY INTO SUNDAY NIGHT. ALSO HAVE THE POTENTIAL FOR EXCESSIVE RAINFALL. UPPER LEVEL LOW WILL DIVE INTO TH GREAT LAKES FROM THE NORTHERN PLAINS LATE THIS WEEKEND WITH YET ANOTHER DYNAMIC SYSTEM. WILL LIKELY BE DEALING WITH A LATE NIGHT MCS TOWARDS THE BEGINNING OF THE SHORT TERM FORECAST BRINGING A WIND THREAT. THIS COULD WORK TO DESTABILIZE THE ATMOSPHERE LATER IN THE DAY WITH COOLING TO THE MID LEVELS AS THE SURFACE RECOVERS UNDER SOLAR INSOLATION...THUS INCREASING THE LOW AND MID LEVEL LAPSE RATES INTO THE LATE AFTERNOON AND EVENING SUNDAY. STORMS WILL FORM ALONG THE STRONG COLD FRONT AND PROPAGATE RAPIDLY WITH AN OBVIOUS WIND THREAT AS WELL AS LARGE HAIL. AS THE SPEED SHEAR INCREASES WITH THE APPROACHING OF THE UPPER LEVEL LOW...SO DOES THE DIRECTIONAL SHEAR OVER THE LOW LEVELS...AND WILL SEE SOME VEERING WITH HEIGHT. RAPID DRYING ALOFT ABOVE 700MB OCCURS AFTER 00Z MONDAY...BUT AS THE UPPER LOW ROTATES INTO LAKE ERIE...ANOTHER AXIS OF MOISTURE WILL DROP IN FROM THE NORTH. THIS KEEPS THE POPS GOING AFTER A SHORT REPRIEVE INTO THE MONDAY TIME FRAME. IN THE END...THIS COLD FRONTAL PASSAGE WILL BRING YET ANOTHER SIGNIFICANT CHANGE IN AIRMASS...IN A JULY THAT HAS SEEN A STEADY DOSE OF THESE COLD FRONTS THAT HAVE USHERED IN INFLUENCES FROM CANADIAN HIGH PRESSURE. MAX TEMPERATURES WILL BE BACK DOWN AROUND 10 TO 15 DEGREES BELOW NORMAL. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... HIGH PRESSURE BEHIND THE COLD FRONT TAKES CONTROL LATER MONDAY NIGHT THROUGH THE MIDDLE OF NEXT WEEK WITH NEAR NORMAL TEMPERATURES. BLENDED HPC WITH PREVIOUS FORECAST NUMBERS AS THEY LOOK REPRESENTATIVE UNDER HIGH PRESSURE AND SLIGHTLY COOLER NORTHERLY FLOW. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/...
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12Z SATURDAY THRU 12Z SUNDAY... OCCASIONAL MVFR RIVER AND VALLEY FOG TIL 13Z...EXCEPT LOCALLY IFR AT EKN. OTHERWISE...SCT-BKN CLOUDS AOA 8000 FEET AGL THRU 15Z ASSOCIATED WITH WEAK UPPER DISTURBANCE. AFTER 15Z...GENERALLY SCATTERED DIURNAL CU. A THUNDERSTORM COMPLEX WILL BEGIN TO AFFECT AREA AFTER 03Z FROM THE WEST AND NORTHWEST...WHICH MAY REACH OHIO RIVER BY 06Z...AND OVER MOST OF THE AREA BY 12Z SUNDAY. GREAT UNCERTAINTY ABOUT THE DEVELOPMENT AND TRACK OF ORGANIZED THUNDERSTORMS...LEADS TO A TAF FORECAST THAT BRINGS GENERAL MVFR CONDITIONS WITH SHOWERS AND SCATTERED STORMS FROM WEST TO EAST TONIGHT...ESPECIALLY AFTER MIDNIGHT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY... FORECAST CONFIDENCE: HIGH TODAY...LOW TONIGHT. ALTERNATE SCENARIOS: TIMING AND COVERAGE OF EARLY MORNING FOG WILL VARY DEPENDING ON CLOUD COVER. THUNDERSTORM COMPLEX OVER AREA SATURDAY NIGHT IS UNCERTAIN. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05 EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 18Z SUNDAY... IFR POSSIBLE IN ROUNDS OF CONVECTION SUNDAY AND SUNDAY NIGHT.
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&& .RLX WATCHES/WARNINGS/ADVISORIES...
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WV...FLASH FLOOD WATCH FROM MIDNIGHT EDT TONIGHT THROUGH LATE SUNDAY NIGHT FOR WVZ005>011-013>020-024>040-046-047. OH...FLASH FLOOD WATCH FROM MIDNIGHT EDT TONIGHT THROUGH LATE SUNDAY NIGHT FOR OHZ066-067-075-076-083>087. KY...FLASH FLOOD WATCH FROM MIDNIGHT EDT TONIGHT THROUGH LATE SUNDAY NIGHT FOR KYZ101>103-105. VA...FLASH FLOOD WATCH FROM MIDNIGHT EDT TONIGHT THROUGH LATE SUNDAY NIGHT FOR VAZ003-004.
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&& $$ SYNOPSIS...JMV/26 NEAR TERM...JMV/50 SHORT TERM...26 LONG TERM...ARJ AVIATION...JMV/50

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