Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 190147 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 947 PM EDT FRI APR 18 2014 .SYNOPSIS... AN AREA OF LOW PRESSURE MOVING THROUGH THE SOUTHEASTERN UNITED STATES WILL PUSH SOME PRECIPITATION INTO NORTHWEST NORTH CAROLINA...AND INTO VIRGINIA UP TO ROUTE 460...TONIGHT AND TOMORROW. HIGH PRESSURE WILL THEN BUILD ALONG THE EASTERN SEABOARD AND BRING FAIR WEATHER TO THE REGION INTO THE FIRST PART OF NEXT WEEK. HOWEVER...A COLD FRONT WILL MOVE THROUGH ON TUESDAY WITH SHOWERS AND THUNDERSTORMS...FOLLOWED BY BREEZY CONDITIONS AND DRY WEATHER FOR MIDWEEK. && .NEAR TERM /THROUGH SATURDAY/...
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AS OF 947 PM EDT FRIDAY... INCREASED POPS ACROSS NORTH CAROLINA THIS EVENING INTO SATURDAY MORNING TO MATCH UP BETTER WITH LATEST RADAR TRENDS. ALSO ADJUSTED TEMPERATURES FOR TONIGHT INTO SATURDAY. AS OF 806 PM EDT FRIDAY... THE CHALLENGE IN THE FORECAST TONIGHT IS THE NORTHERN EDGE OF CLOUDS/RAINFALL ASSOCIATED WITH THE VERTICALLY STACKED COASTAL LOW THAT MOVES EAST ACROSS NORTHERN FLORIDA TONIGHT AND OFF THE SOUTHEAST COAST SATURDAY. LOOKS LIKE THE RICHER MOISTURE ARRIVES OVERNIGHT WITH A DEVELOPING UPSLOPE FLOW INTO THE NORTHWEST NORTH CAROLINA MOUNTAINS LATE. OVERALL LEANED TOWARDS A SLIGHTLY SLOWER SOLUTION TONIGHT GIVEN DRY ADVECTION FROM HIGH PRESSURE TO THE NORTH AND GRADUAL DEVELOPMENT OF DEEP CONVECTION ALONG THE COAST EARLY SATURDAY. KEPT THE ENSEMBLE BLEND FOR POPS SIMILAR TO LATEST WPC WITH MOISTURE HOLDING SOUTH OF HIGHWAY 460. MODELS REMAIN IN THEIR RESPECTIVE CAMPS WITH NAM STILL KEEPING MOST OF RAIN SOUTH...WHILE THE GFS HAS A DEFORMATION BAND ACROSS SRN VA/NW NC BY SATURDAY MORNING. LATEST RUN OF RNK WRFARW WAS DRIER AND FURTHER SOUTH WITH RAIN AND QPF FOR TONIGHT. IT APPEARS THAT BETTER LIFT AND COLUMN SATURATION DEVELOPS AFTER MIDNIGHT NORTHWEST NORTH CAROLINA INTO SOUTHERN VIRGINIA EARLY SATURDAY WHERE LIKELY POTENTIAL FOR LIGHT QPF. MODIFIED TEMPERATURES AND DEWPOINTS FOR TONIGHT INTO SATURDAY. MORE CHANGES LATER TONIGHT. AS OF 230 PM EDT FRIDAY... MAIN CONCERN CONTINUES WITH NORTHWARD PROGRESSION OF CLOUDS/RAINFALL OVER THE NEXT 24 HOURS ASSOCIATED WITH THE VERTICALLY STACKED COASTAL LOW THAT WILL DRIFT EAST ACROSS NRN FLORIDA TONIGHT AND OFF THE SE COAST SATURDAY. THIS SYSTEM WILL PUSH DEEPER MOISTURE NORTH OVERNIGHT WITH A DEVELOPING UPSLOPE COMPONENT INTO THE NW NC MOUNTAINS LATE. HOWEVER MODELS REMAIN IN SIMILAR CAMPS AS BEFORE WITH THE NAM KEEPING MOST PRECIP TO THE SOUTH...WHILE THE GFS HAS A DEFORMATION BAND ACROSS SRN VA/NW NC BY MORNING...LEAVING THE CANADIAN AND NEW EC BASICALLY IN BETWEEN WITH MOST RAINFALL ACROSS THE SOUTH/EAST BY EARLY SAT. LATEST CONSENSUS INCLUDING WPC OUTPUT SUGGESTS A SLOWER SOLUTION IN ORDER TONIGHT GIVEN DRY ADVECTION FROM HIGH PRESSURE TO THE NORTH AND GRADUAL DEVELOPMENT OF DEEP CONVECTION ALONG THE COAST EARLY SAT. THUS HAVE CUT BACK ON POPS ENTERING THE SOUTH THIS EVENING WITH BETTER LIFT AND COLUMN SATURATION AFTER MIDNIGHT NW NC INTO SOUTHERN VA EARLY SAT WHERE MAINTAINED LOW LIKELYS FOR LIMITED QPF. NORTHWARD EXTENT ALSO IFFY AS APPEARS THE BLUE RIDGE TO SERVE AS A BACKBOARD WITH MID LEVEL DRY HOLDING ANY PRECIP ALONG/SOUTH OF HIGHWAY 460...SO MAINLY CHANCE POPS IN THESE SPOTS. OTRW MAINLY CLOUDY AND DRY ELSW WITH UNIFORM LOWS MOSTLY IN THE UPPER 30S TO MID 40S. GUIDANCE SHOWS THE DEFORMATION AXIS STRETCHING OUT ALONG OR SOUTH OF THE VA/NC BORDER SAT UNDER CONFLUENCE ALOFT AND SOUTH OF HIGH PRESSURE BUILDING IN FROM THE NORTH. AGAIN LOOKS LIKE MOST -RA/DZ ALONG AND SOUTH OF THE BORDER BUT A TIGHT GRADIENT LIKELY FROM LOW CLOUDS/PRECIP SOUTH TO HIGH/MID CLOUDS AND LITTLE -RA NORTH AND WEST. ENSEMBLES SHOW PRECIP PIVOTING ACROSS THE EAST THROUGH MUCH OF SATURDAY BUT SEEMS OVERDONE WITH THE LOW LEVEL FLOW MORE NE THAN EAST WHICH SOMETIMES ACTS TO LIMIT PRECIP INTO AN ENHANCED WEDGE. THEREFORE MAINTAINED CONTINUITY WITH LINGERING LIKELY POPS FAR SOUTH/SE DURING THE MORNING AND CHANCES UP TO 460...THEN DRYING FROM NW TO SE SAT AFTERNOON WITH MOST RAINFALL EXITING LATE. HIGH TEMPS VERY TRICKY WITH LARGE MOS SPREADS ATTM PENDING DEGREE OF CLOUDS AND RAIN WHICH COULD KEEP SOME SPOTS IN THE 40S TO AROUND 50 IF PRECIP IS MORE WIDESPREAD. OTRW STAYING CLOSER TO THE COOLER MAV MOS SOUTH/EAST BUT SLIGHTLY WARMER NORTH WHERE SOME SUN POSSIBLE.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... AS OF 300 PM EDT FRIDAY... BY SATURDAY NIGHT...THE LOW WHICH AFFECTED US ON SATURDAY SHOULD SINK FAR ENOUGH SEWD TO PULL THE PCPN SHIELD OUT OF OUR AREA. THEN...HIGH PRESSURE RIDGING DOWN THE COAST COMBINED WITH NELY FLOW AROUND THE LOW WILL KEEP A BRISK WIND OVER THE PIEDMONT. NEXT SYSTEM BEGINS TO APPROACH ON MONDAY AND MODELS SPIT OUT SOME LIGHT QPF WITH WEAK DYNAMIC SUPPORT. WILL OPT TO KEEP MONDAY DRY AND LEAVE POPS JUST BELOW THRESHOLD. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 200 PM EDT FRIDAY... MAIN WEATHER MAKER THOUGH THE EXTENDED WILL BE CFROPA ON TUESDAY. THE FRONT LOOKS TO HAVE GOOD SUPPORT...AND AREAS EAST OF THE BLUE RIDGE LOOK TO DESTABILIZE A BIT AHEAD OF THE FRONT TUESDAY AFTERNOON. WILL GO WITH LLIKELY POPS AND CONFINE CHC THUNDER TO ERN AREAS. NOT SEEING MUCH IN THE DATA TO INDICATE MORE THAN GENERAL THUNDERSTORMS ATTM. BELIEVE THERE WILL BE A CHC FOR SOME UPSLOPE RAIN SHOWERS IN CAA WEST OF THE BLUE RIDGE AND WILL INDICATE THIS FOR WEDNESDAY NIGHT...AND WEDNESDAY LOOKS BREEZY AS HIGH PRESSURE BUILDS IN WITH QUIET WX FOR THURSDAY. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... AS OF 720 PM EDT FRIDAY... OVC-VFR CONDITIONS WILL REMAIN THROUGH THE EVENING THEN LOWER TO LOW- END VFR STARTING AROUND 02Z SAT FROM SOUTH TO NORTH. STILL EXPECT CIGS TO LOWER DURING THE MORNING BUT DEPTH OF MOISTURE REMAINS IN QUESTION UNDER DRY MID LEVELS AND DEVELOPING NE FLOW THROUGH THE REMAINDER OF THE PERIOD. MODELS REMAIN VARIED ON HOW FAR NORTH TO TAKE LOWER CIGS AND RAINFALL AFTER MIDNIGHT WITH AN ENSEMBLE BLEND PROVIDING A RANGE FROM MOSTLY VFR OVERNIGHT AT LWB TO DEVELOPING IFR ALONG AND EAST OF THE BLUE RIDGE BY DAYBREAK SATURDAY. APPEARS MVFR TO OCNL IFR MOST LIKELY FROM ROA-LYH SOUTH TO DAN WHILE A PERIOD OF MVFR LIKELY AT BCB AND POSSIBLE AT BLF ALTHOUGH LOW CONFIDENCE AT THIS POINT. RAINFALL INDUCED VSBY REDUCTIONS ALSO IFFY WITH MVFR LIKELY AT DAN AND PERHAPS ROA/LYH IF THINGS SATURATE ENOUGH BY EARLY SATURDAY WHICH APPEARS POSSIBLE. ELSW INCLUDING SOME -RA/DZ MENTION AT BCB AND BLF LATE BASED ON LATEST NON NAM GUIDANCE TRENDS. LIGHT/VRBL WINDS TO BACK TO THE NORTHEAST ONCE RAIN MOVES INTO THE FORECAST AREA EARLY SATURDAY MORNING. SPEEDS WILL STAY UNDER 6KTS THROUGH THE MORNING...THEN INCREASE AS LOW DRIFTS OFF THE SOUTHEAST COAST. WIND GUSTS ACROSS THE PIEDMONT (DAN/LYH) COULD APPROACH 20KTS BY THE AFTERNOON. POOR FLYING CONDITIONS COULD PERSIST OVER THE SOUTH AND EAST INTO SATURDAY AFTERNOON WITH THE BELT OF DEEPER MOISTURE UNDER THE UPPER LOW SLOW TO EXIT. PERIODS OF -RA/DZ MAY ALSO LINGER EAST OF THE BLUE RIDGE WHERE ROA/LYH/DAN COULD GET STUCK IN MVFR TO IFR CIGS AND SOME LIMITED VSBY REDUCTION PENDING NORTHWARD EXTENT OF THE RAINFALL ESPCLY THROUGH MIDDAY. EXTENDED AVIATION DISCUSSION... THE UPPER LOW SLOWLY EXITS TO THE EAST SUNDAY AND HIGH PRESSURE RETURNS BRINGING A RETURN TO VFR CONDITIONS INTO EARLY NEXT WEEK. THE NEXT COLD FRONT APPROACHES MONDAY NIGHT WITH MORE SHOWERS AND POSSIBLE THUNDERSTORMS INCLUDING PERIODS OF MVFR. FRONT EXITS TUESDAY NIGHT RESULTING IN A RETURN TO VFR WEDNESDAY EXCEPT FOR MVFR CIGS OVER THE FAR WESTERN SITES IN SE WEST VA. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...MBS NEAR TERM...JH/KK SHORT TERM...MBS LONG TERM...MBS AVIATION...JH/RCS

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