Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 191402 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1002 AM EDT SAT APR 19 2014 .SYNOPSIS...
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A DEEP AREA OF LOW PRESSURE ALOFT ACROSS THE SOUTHEAST STATES WILL MOVE VERY SLOWLY EASTWARD THROUGH THE WEEKEND...MOVING OFF THE COAST BY MONDAY...KEEPING CLOUDS AND LIGHT RAIN ACROSS SOUTHERN SECTIONS TODAY INTO EARLY SUNDAY. HIGH PRESSURE WILL BUILD ACROSS THE REGION FOR LATER SUNDAY INTO MONDAY. BY TUESDAY...A COLD FRONT AND ASSOCIATED UPPER TROUGH WILL MOVE INTO THE REGION FROM THE NORTHWEST BRINGING A CHANCE FOR SHOWERS AND THUNDERSTORMS...FOLLOWED BY BREEZY AND COOLER CONDITIONS FOR THE MID PART OF NEXT WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 930 AM EDT SATURDAY... ELONGATED BAND OF RAIN ASSOCIATED WITH THE MID LEVEL DEFORMATION ZONE OF THE BROAD UPPER LOW ACROSS NORTH FLORIDA REMAINS ACROSS THE FAR SOUTHERN TIER THIS MORNING. HOWEVER LATEST MORNING SOUNDINGS CONTINUE TO SHOW A STRONG NE FLUX OF DRIER AIR IN THE LOWER LEVELS AS EVIDENCED VIA THE RNK RAOB. THIS HAS CAUSED SOME DRYING TO TAKE PLACE ALONG THE BLUE RIDGE SOUTH TO NEAR THE VIRGINIA BORDER WHICH IS CLOSER TO THE LATEST HRRR SOLN THAT ATTEMPTS TO SHIFT ALL THE PRECIP SOUTH THIS AFTERNOON. GFS CONTINUES TO MAINTAIN THE AXIS OF LIGHT RAIN WITH MORE EASTERLY INFLOW OFF THE ATLANTIC AS THE UPPER SYSTEM ONLY DRIFTS TO OFF THE SE COAST BY THIS EVENING. THIS SCENARIO APPEARS MORE IN LINE WITH A SHARP GRADIENT FROM SOME SUN NORTH...TO CLOUDS CENTRAL SECTIONS...WITH CONTINUED PERIODS OF -RA VA/NC BORDER AND POINTS SOUTH AS THE BAND TENDS TO STRETCH OUT WHILE SLOWLY DIMINISHING THROUGH THE AFTERNOON. THIS SUPPORTS KEEPING CAT/LIKELY POPS A WHILE LONGER ACROSS MUCH OF NW NC INTO SOUTHSIDE VIRGINIA WITH A QUICK DROPOFF TO DRY CONDITIONS FROM JUST SOUTH OF HIWAY 460 AND POINTS NORTH. HIGH TEMPS REMAIN TRICKY WITH POTENTIAL FOR HIGHS TO STRUGGLE TO TOP 50 UNDER THE RAIN WHILE REACHING THE LOW/MID 60S FAR NORTH/WEST WITH 56-63 BCB-ROA-LYH CORRIDOR PENDING DEGREE OF ANY BREAKS. THUS INCREASED THE GRADIENT THIS AFTERNOON SINCE ALREADY ABOVE HIGHS IN SPOTS NORTH OF THE MAIN RAIN/CLOUD SHIELD ATTM. PREVIOUS DISCUSSION... MAIN CONCERN THROUGH THE NEAR TERM CONTINUES TO BE SLOW MOVING...INCREASINGLY VERTICALLY STACKED UPPER LOW ACROSS THE SOUTHEAST STATES. FINALLY...AFTER SEVERAL DAYS OF DIFFERING SOLUTIONS AMONG THE MODELS...THE GFS/ECMWF/NAM/CANADIAN HAVE ALL CONVERGED ON A SIMILAR SOLUTION. EXPECT -RA TO GENERALLY REMAIN IN AN AREA THROUGH THIS EVENING SIMILAR TO WHERE IT IS...NAMELY MOSTLY ALONG AND EAST OF THE BLUE RIDGE FROM TNB-HLX-LYH. WITH THE UPPER LOW MOVING ALMOST DUE EAST THROUGH THE PERIOD...SEE LITTLE NORTHWARD PROGRESS OF THE RAIN FROM THESE POINTS...BUT BY THE SAME TOKEN...LITTLE SOUTHWARD PROGRESS UNTIL THE UPPER LOW MOVES CLOSER TO THE COAST...ALLOWING DRIER NE FLOW TO ADVECT SOUTHWARD INTO THE REGION. FOR AREAS FURTHER NORTH AND WEST...CONSIDERABLE HIGH CLOUDS WILL PERSIST AND EVEN SOME MID CLOUDS ARE EXPECTED TO REACH THE ALLEGHANY FRONT...BUT LITTLE TO NO PRECIPITATION WEST OF THE BLUE RIDGE. GFS/ECMWF BOTH CLEARLY DEPICT A SMALL DEFORMATION ZONE TO DEVELOP ACROSS NORTHWEST NC THIS EVENING...PROLONGING THE PRECIPITATION IN THAT AREA. HAVE INCREASED POPS TO LIKELY AND CATEGORICAL AND EXTENDED LONGER INTO OUR SOUTHERN TIER OF COUNTIES THAN EARLIER ADVERTISED. SYNOPTIC PATTERN AND -RA...SOME WHAT OF AN INSITU WEDGE REINFORCED WITH NE FLOW AROUND SE U.S. DEVELOPING SFC LOW PRESSURE...WILL KEEP THE PIEDMONT THE COOLEST TODAY. HAVE LEANED TOWARD THE ECMWF MOS...WHICH WAS THE COOLEST AMONG THE MAV/MET/ECS. HOWEVER...EVEN UNDERCUT IT BY ABOUT ONE CATEGORY IN THE RAINY PIEDMONT AREAS. THE MOUNTAINS OF NORTHWEST NC WILL STRUGGLE TO REACH 50. THE WARMEST AREAS TODAY SHOULD BE WEST OF THE ALLEGHANY FRONT...LWB-BLF- MKJ...WHERE LOW 60S ARE POSSIBLE IF THE CLOUDS THIN OUT ENOUGH DURING THE MID AND LATE AFTERNOON. WINDS WILL REMAIN NE EAST OF THE ALLEGHANY FRONT AND GENERALLY E-SE TO THE WEST. SPEEDS WILL INCREASE DURING THE AFTERNOON AND EVENING AS A TIGHT PRESSURE GRADIENT DEVELOPS BETWEEN THE LOW PRESSURE ACROSS SC AND HIGH PRESSURE RIDGING SOUTHWARD FROM NEW ENGLAND.
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&& .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... AS OF 400 AM EDT SATURDAY... FOR EASTER SUNDAY...MAY SEE A FEW RESIDUAL SPRINKLES ACROSS THE SOUTHSIDE AND THE NORTH CAROLINA PIEDMONT TO START THE DAY...HOWEVER THESE WILL QUICKLY EXIT THE AREA AS LOW PRESSURE EXITS OFF THE SOUTHEAST COAST. OTHERWISE...EXPECT CLEARING SKIES AS HIGH PRESSURE REMAINS WEDGED AGAINST THE EASTERN FACE OF THE APPALACHIANS... RESULTING IN A LIGHT AND GENERALLY EASTERLY WIND FLOW. WITH THE COOL HIGH PRESSURE WEDGE IN PLACE...WENT A LITTLE BELOW MODEL GUIDANCE FOR AFTERNOON TEMPERATURES...WITH HIGHS CLIMBING INTO THE MID AND UPPER 60S MOST LOCATIONS OUTSIDE OF THE HIGHER RIDGES. LIGHT WINDS AND MOSTLY CLEAR SKIES WILL ALLOW FOR STRONG RADIATIONAL COOLING SUNDAY NIGHT...WITH LOWS BOTTOMING OUT IN THE UPPER 30S AND LOW 40S...WITH A FEW MOUNTAIN VALLEYS DROPPING BELOW FREEZING. UPPER LEVEL RIDGING BECOMES MORE FIRMLY ESTABLISHED FOR MONDAY AS THE SURFACE HIGH PRESSURE WEDGE SHOWS SIGNS OF BREAKING DOWN. EXPECT WARMER TEMPERATURES DESPITE INCREASING MID AND HIGH CLOUDS...WITH HIGHS REACHING INTO THE UPPER 60S AND LOW 70S. WINDS WILL BECOME INCREASINGLY SOUTHWESTERLY THROUGH THE DAY AHEAD OF AN APPROACHING COLD FRONT...AND THE WARMER AIR POOLING IN FROM THE GULF COAST REGION WILL MAKE FOR MILD MONDAY NIGHT LOWS...GENERALLY IN THE UPPER 40S AND LOW 50S. SHOWER ACTIVITY WILL ENTER FROM THE WEST AFTER SUNRISE TUESDAY AS THE COLD FRONT ADVANCES EAST ACROSS KENTUCKY/TENNESSEE. GFS/ECMWF/ CANADIAN FORECAST MODELS ALL INDICATE DECENT INSTABILITY DEVELOPING DURING THE AFTERNOON ALONG AND EAST OF THE BLUE RIDGE AS A LEE SIDE TROUGH SETS UP...WHILE STRONG HEATING WILL ALLOW TEMPERATURES TO CLIMB INTO THE MID AND UPPER 70S. AS SUCH...CONDITIONS APPEAR FAVORABLE FOR SCATTERED THUNDERSTORMS TO DEVELOP...A FEW OF WHICH WILL LIKELY BECOME STRONG TO SEVERE. AT THIS POINT...BOTH HAIL AND GUSTY WINDS WOULD BE CONCERNS. THE COLD FRONT WILL PASS ACROSS THE AREA DURING THE EVENING...EXITING TO THE EAST AFTER MIDNIGHT WEDNESDAY. A FEW UPSLOPE RAIN SHOWERS MAY LINGER ACROSS THE WESTERN RIDGES THROUGH THE NIGHT...OTHERWISE CLEARING CONDITIONS ARE EXPECTED. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 400 AM EDT FRIDAY... BELIEVE THERE WILL STILL BE A CHANCE FOR SOME UPSLOPE RAIN SHOWERS IN CAA WEST OF THE BLUE RIDGE EARLY WEDNESDAY...IN ADDITION TO BREEZY CONDITIONS AS HIGH PRESSURE BUILDS IN FROM THE NORTHWEST. EXPECT QUIET WEATHER FOR THURSDAY AS HIGH PRESSURE PASSES OVERHEAD. SHOWERS AND POSSIBLE THUNDERSTORMS WILL MOVE IN ON FRIDAY AS ANOTHER COLD FRONT APPROACHES. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... AS OF 740 AM EDT SATURDAY... UPPER LOW PRESSURE AREA SOUTHEAST U.S. WILL CONTINUE TO CLOSE OFF AND DRIFT VERY SLOWLY EAST ALONG THE GULF COAST TO THE SOUTHEAST ATLANTIC COAST THROUGH THE PERIOD. MARITIME EASTERLY FLOW ON THE NORTH SIDE WILL CONTINUE TO ADVECT LIGHT RAIN INTO THE SOUTHERN PORTION OF THE CWA...INCLUDING DAN. A FEW SPRINKLES MAY REACH ROA/LYH...BUT NOT ENOUGH TO REDUCE VSBY. THE -RA CONTINUES TO FALL OUT OF VFR CIGS...MOSTLY AOA 080 AT THIS TIME. VERY DRY MID- LEVEL AIR WILL CONTINUE TO GRADUALLY MOISTEN...BUT CIGS APPEAR DESTINED TO REMAIN MOSTLY VFR THROUGH THE TAF VALID PERIOD...BUT WILL LIKELY LOWER TO LOW END VFR LYH-DAN FOR A PERIOD LATE MORNING/EARLY AFTERNOON...BEFORE THE DEEPER MOISTURE ASSOCIATED WITH THE UPPER LOW SPREADS FURTHER EAST LATE AFTERNOON/EVENING. UNLIKE YESTERDAY MORNING...SFC FLOW NOW NE AS OPPOSED TO SE...WHICH IS HELPING TO TRANSPORT DRIER AIR INTO THE REGION FROM THE NORTHEAST MAKING IT HARD TO REALIZE ANYTHING WORSE THAN VFR AT THIS POINT. OCCASIONAL MVFR VSBYS ARE ALSO POSSIBLE DAN...BUT ELSEWHERE DO NOT EXPECT ENOUGH -RA TO WARRANT MENTION OF ANY VSBYS LESS THAN VFR. WINDS WILL BE ON THE INCREASE AS THE DAY PROGRESSES WITH A TIGHTENING OF THE PRESSURE GRADIENT BETWEEN NORTHEASTERN U.S. HIGH PRESSURE AND SOUTHEAST U.S. LOW. EXPECT ENE 10-12KTS WITH GUSTS TO 20KTS ACROSS THE PIEDMONT BY AFTERNOON AND EVENING...DIMINISHING AFT 00Z...BUT LOW END GUSTS POSSIBLE MUCH OF THE NIGHT ACROSS THE PIEDMONT. MEDIUM CONFIDENCE IN CIGS AND VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND DIR/SPD THROUGH THE TAF VALID PERIOD. 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...RAB NEAR TERM...JH/RAB SHORT TERM...NF LONG TERM...MBS/NF AVIATION...RAB/RCS

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