Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 210812 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 412 AM EDT THU AUG 21 2014 .SYNOPSIS... ABUNDANT MOISTURE REMAINS IN PLACE WITH A FRONT REMAINING NEARLY STATIONARY TO THE WEST THROUGH THE WEEKEND. HIGH PRESSURE WILL TRY TO NOSE IN FROM THE NORTHEAST EARLY NEXT WEEK AS UPPER RIDGE BUILDS. && .NEAR TERM /THROUGH TODAY/... FORECAST FACTORS THIS PERIOD INCLUDE WHERE WARM FRONT SETTING UP W OF THE AREA WILL BE...WHERE CONVECTIVE COMPLEXES FORMING ALONG AND ON COOL SIDE OF THE FRONT WILL TRACK...AND THE TIMING OF THESE COMPLEXES. ONE SUCH COMPLEX ALONG THE FRONT AND 310K PRESSURE GRADIENT SHOULD TRACK MAINLY S OF THE CWA THIS MORNING AS LONG AS IT CONTINUES TURNING RIGHT. SECOND AREA OF RAINFALL FORMING FARTHER N AND MORE STRATIFORM IN NARROW STRIP THROUGH CHICAGO ALONG A SECOND PRESSURE GRADIENT ON THE 300K AND 305K SURFACES ALSO MOVING SEWD AND SHOULD ARRIVE IN FCST AREA AFTER DAYBREAK THIS MORNING AND TRAVERSE THROUGH THE MIDDAY HOURS AND INTO THIS AFTERNOON. THIS IS NOT THE MOST FAVORED TIME OF DAY FOR WARM ADVECTION PRECIPITATION / CONVECTION SO TOUGH TO FIGURE WHAT THE COVERAGE WILL BE. ANOTHER COMPLEX WAS STARTING TO GO OFF UPSTREAM OF THAT...EITHER REMNANTS OF IT OR LATE DAY CONVECTION FIRING IN THE WAKE OF THE AFTERNOON PRECIPITATION GIVEN ANY BREAKS OF SUNSHINE...WARRANT HOLDING THE HIGH CHANCE TO LIKELY POPS GOING INTO THE EVENING BEFORE TRAILING OFF NW TO SE. TIMING OF PRECIPITATION ALONG A WARM FRONT GETS DICEY QUICKLY WITH TIME EVEN BY THE END OF THE NEAR TERM...BUT MODEL DATA SUGGESTS ANOTHER COMPLEX APPROACHING FROM THE NW AS DAWN FRI APPROACHES. AREAS OF POST RAIN LOW CLOUDS AND FOG ARE LIKELY IN THE INTERIM OVERNIGHT TONIGHT. MET REFLECTS RAINY DAY TODAY IN ITS LOW TEMPERATURE GUIDANCE. OPTED TO STAY CLOSE TO PREVIOUS PACKAGE...WHICH IS BETWEEN IT AND THE HIGHER MAV. PRECIPITATION IS LIKELY TO ALLOW FOR BREAKS OF SUNSHINE THIS AFTERNOON ALTHOUGH IT WILL NOT FALL APART AS QUICKLY AS IT DID WED MORNING. LOWS TONIGHT LOOKED GOOD IN LIGHT OF LATEST BIAS CORRECTED GUIDANCE. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... UNSETTLED WEATHER CONTINUES IN THE SHORT TERM PERIOD...WITH SEVERAL UPPER WAVES MOVING THROUGH THE AREA IN THE NORTH/NORTHWESTERLY FLOW ALOFT. ONE SUCH WAVE EXPECTED FRIDAY THROUGH FRIDAY NIGHT...FOLLOWED BY ADDITIONAL WAVES OVER THE WEEKEND. HEAVY RAIN IS EXPECTED ACROSS THE AREA FRIDAY AND FRIDAY NIGHT...PARTICULARLY ACROSS THE NORTH...WITH PLENTY OF UPPER AIR SUPPORT IN PLACE DURING THE PERIOD. PW VALUES FRIDAY...PROGGED TO BE AROUND 1.8 INCHES...AND WPC HAS PLACED THE ENTIRE CWA IN A SLIGHT RISK FOR EXCESSIVE RAINFALL FRIDAY NIGHT AND SATURDAY. WITH PLENTY OF TIME LEFT TO ISSUE ANY WATER HEADLINES...WILL CONTINUE TO HIGHLIGHT THE ISSUE IN THE HWO. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... WILL SLOWLY TRANSITION TO A DRIER REGIME AS THE UPPER HEIGHTS SLOWLY BUILD OVER THE AREA COURTESY OF THE STOUT RIDGE AMPLIFYING OVER MS VALLEY. THE OPPRESSIVE HEAT SHOULD STAY W OF THE AREA BUT WILL STILL BE CONTENDING WITH THE MUGGIES WITH TEMPS RUNNING 3 TO 5 DEGREES ABOVE NORMAL DAY AND NIGHT. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... SOME DENSE VALLEY FOG OVERNIGHT INTO THU MORNING...BUT PATCHY IFR AND MVFR CLOUD WILL RAISE/KEEP VSBY MVFR OR BETTER AT TIMES. ALTOCU WILL ALSO HAVE MITIGATING AFFECT ON FOG...ESPECIALLY SOUTHERN TAF SITES. AS A RESULT...HAVE HIT THE DENSE FOG HARDEST IN THE CODE FOR THE NRN SITES. CLUSTERS OF SHOWERS AND THUNDERSTORMS WILL RIDE E TO SEWD ALONG A WARM FRONT SET UP ACROSS THE LOWER OHIO VALLEY THIS TAF PERIOD. ONE CLUSTER WILL CROSS DURING THE DAY THU. SINCE THE DAYTIME HOURS ARE NOT A FAVORABLE TIME FOR CONVECTION ASSOCIATED WITH WARM FRONT...IT IS DIFFICULT TO DETERMINE HOW MUCH AREA COVERAGE THERE WILL BE...BUT THERE SHOULD BE A DECREASE IN COVERAGE THU NT. THE NEXT COMPLEX SHOULD ARRIVE FRI MORNING...BEYOND THE CURRENT 24 HR TAF PERIOD. POST RAIN LOW CLOUD AND FOG MAY FORM IN THE INTERIM. SFC FLOW WILL BE LIGHT AND VARIABLE...MAINLY W...WHILE LIGHT TO MODERATE W FLOW ALOFT BECOMES NW THU. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY... FORECAST CONFIDENCE: LOW TO MEDIUM. ALTERNATE SCENARIOS: TIMING AND INTENSITY OF FOG WILL VARY IN RESPONSE TO CHANGING CIGS INCLUDING MVFR TO IFR CIGS. IFR IS POSSIBLE BUT DIFFICULT TO TIME IN SHOWERS AND THUNDERSTORMS THU. AREAS OF POST RAIN FOG AND LOW CLOUD MAY FORM THU NT. 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. DATE THU 08/21/14 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 CRW CONSISTENCY M M M H L L L L M H L M HTS CONSISTENCY H H M M M H H M M M M M BKW CONSISTENCY H H M M M H H M M M M M EKN CONSISTENCY L L L L L L L L L H H H PKB CONSISTENCY L L L L L L L L M H H H CKB CONSISTENCY L L L L L L L M H M M M AFTER 06Z FRIDAY... IFR CONDITIONS POSSIBLE IN ANY ROUND OF CONVECTION FRI THROUGH FRI NT. LATE NIGHT AND EARLY MORNING POST RAIN FOG AND STRATUS ALSO POSSIBLE EARLY FRI MORNING AND SAT MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JS/ARJ/30 NEAR TERM...JS/ARJ/TRM SHORT TERM...30 LONG TERM...30 AVIATION...TRM

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