Area Forecast Discussion
Issued by NWS Blacksburg, VA

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719 FXUS61 KRNK 031757 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 157 PM EDT TUE MAY 3 2016 .SYNOPSIS... A COLD FRONT WILL CONTINUE TO SLOWLY MOVE SOUTHWARD THROUGH WEDNESDAY. MEANWHILE...LOW PRESSURE DEEPENING ACROSS THE GREAT LAKES WILL DRIFT SOUTHWARD INTO THE SOUTHERN APPALACHIANS BY THURSDAY...REMAINING OVER THE REGION UNTIL LATE IN THE WEEKEND. WIDESPREAD RAIN TODAY WILL GIVE WAY TO AN UNSETTLED WEATHER PATTERN WITH SCATTERED TO NUMEROUS SHOWERS AND UNSEASONABLY COOL TEMPERATURES DURING THE LATER HALF OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1000 AM EDT TUESDAY... SOME MINOR ADJUSTMENTS TO THE GRIDS THIS MORNING TO ACCOUNT FOR CURRENT RADAR AND SATELLITE TRENDS. SATELLITE SUPPORTS GUIDANCE TRENDS FOR THINNING OUT THE CLOUDS AND THIS SHOULD HELP GET SOME SURFACED BASED INSTABILITY GOING FOR THIS AFTERNOON...LEADING TO SHOWER/THUNDERSTORM FORMATION. THE MOST LIKELY SCENARIO WILL BE FOR THE BULK OF ACTIVITY TO FORM THIS AFTERNOON EAST OF THE BLUE RIDGE WHERE THE POOL OF INSTABILITY WILL BE GREATER...BUT THE BEST SUPPORT FOR SEVERE WILL BE FURTHER TO THE EAST. WILL STILL HAVE TO KEEP A VIGILANT EYE ON STORMS THROUGH THE AFTERNOON AS COOL TEMPS ALOFT WILL STILL SUPPORT HAIL AND PWATS REMAIN HIGH ACROSS THE PIEDMONT WHERE LOCALLY HEAVY DOWNPOURS ARE POSSIBLE. HIGHS IN THE MID 70S EAST TO MID/UPPER 60S WEST SHOULD BE GOOD FOR TODAY. PREVIOUS AFD... UNSETTLED WEATHER PATTERN TO CONTINUE...BUT SEVERE THREAT AND FLOODING THREAT GREATLY DIMINISHED. BIG QUESTION FOR TODAY IS WHETHER OR NOT THERE WILL BE A RESURGENCE OF CONVECTION ALONG THE FRONT AS A WAVE OF LOW PRESSURE RIDES ALONG THE FRONT. MODELS TO VARYING DEGREES INCREASE INSTABILITY ACROSS NORTH CENTRAL NC INTO SOUTHSIDE VA...WHERE SPC HAS INDICATED A SLIGHT RISK...WITH A MARGINAL RISK AS FAR NORTH AND WEST AS THE BLUE RIDGE. HOWEVER...SFC LOW PRESSURE IS PROGGED TO RIDE MAINLY JUST S-E OF THE CWA ALONG THE FRONT AS IT CONTINUES TO SLOWLY SAG SOUTHEAST. THUS...FEEL SEVERE THREAT IS LIMITED AT BEST FOR OUR CWA...AND IF SO LIKELY CONFINED TO THE CASWELL/HALIFAX AREA. ECMWF LEAST IMPRESSIVE ABOUT THUNDER THREAT FOR TODAY...WHILE GFS/NAM MORE FAVORABLE. OVERALL...SEVERE WEATHER PARAMETERS DO NOT APPEAR FAVORABLE FOR MUCH SEVERE. HAVE INCLUDED MENTION OF THUNDER ACROSS SOUTHSIDE INTO NORTH CENTRAL NC...BUT HAVE REFRAINED FROM MENTIONING ELSEWHERE AND DID NOT MENTION SEVERE AT THIS POINT. ADDITIONAL RAINFALL SHOULD REMAIN BELOW FLASH FLOOD THRESHOLDS...WITH THE HEAVIEST RAIN FALLING ACROSS THE AREAS WITH HIGHER FFG VALUES...NAMELY EAST OF THE BLUE RIDGE. NONETHELESS...LIKELY TO CATEGORICAL POPS ARE IN ORDER FOR MUCH OF THE CWA THROUGH 00Z...DECREASING TO CHANCE AFTER MIDNIGHT FROM WEST TO EAST. MAX TEMPERATURES PROBLEMATIC...BUT THINKING THAT CLOUDS WILL BE ABUNDANT TODAY AS UPPER HEIGHTS CONTINUE TO LOWER...FRONT REMAINS QUASI-STATIONARY ACROSS THE S-SE PORTIONS OF THE REGION...AND LIGHT TO MODERATE RAIN SHOWERS CONTINUE TO MOVE ACROSS THE REGION. HAVE LEANED TOWARD THE COOLER SIDE OF GUIDANCE AS A RESULT. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... AS OF 400 AM EDT TUESDAY... THE COLD FRONT SHOULD FINALLY BE OFFSHORE BY WEDNESDAY. HOWEVER...A DEEP UPPER LEVEL TROUGH FROM HUDSON BAY IN CANADA SHOULD TRACK OVER THE GREAT LAKES DURING THE DAY. AS IT APPROACHES THE MID ATLANTIC ON WEDNESDAY NIGHT...WINDS SHOULD SHIFT TO THE NORTHWEST. A PRETTY STIFF COLD AIR ADVECTION PATTERN TAKES PLACE THROUGH THURSDAY AND FRIDAY...AS THE UPPER LEVEL TROUGH CUTS OFF FROM THE FLOW TO BECOME A CLOSED UPPER LEVEL OVERHEAD. AN OMEGA BLOCK PATTERN WILL RESIDE OVER THE UNITED STATES AS THE UPPER LEVEL LOW SETTLES OVER THE MID ATLANTIC. THEREFORE...COOL AND DAMP CONDITIONS ARE EXPECTED FOR THE REMAINDER OF THIS WORK WEEK. PERIODIC SHOWERS...LOW CLOUDS...AND PATCHY FOG ARE LIKELY. WITH A DEEP COOL POOL OF AIR ALOFT...TEMPERATURES SHOULD DROP TO NEAR OR BELOW NORMAL FOR THE FIRST WEEK OF MAY. FOR EXAMPLE...HIGHS ON THURSDAY SHOULD ONLY REACH THE LOWER 50S TO THE LOWER 60S. ALSO...LOWS ON FRIDAY DIP INTO THE UPPER 30S TO THE UPPER 40S. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 230 PM EDT MONDAY... CUTOFF OVER THE AREA FRIDAY WILL WEAKEN AND DRIFT EAST THIS WEEKEND AS FLOW ALOFT SLOWLY EVOLVES INTO A MORE PROGRESSIVE PATTERN FOR THE SECOND WEEK OF MAY. THE WEEKEND WILL BE OUR TRANSITION BETWEEN THE TWO PATTERNS SO LOOK FOR SATURDAY TO BE THE COOLER OF THE TWO DAYS BUT STILL RESEMBLING SOMETHING CLOSER TO NORMAL WITH RESPECT TO TEMPERATURE...THEN TRENDING ABOVE NORMAL FOR SUNDAY AND MONDAY. HIGHEST ELEVATIONS...SUCH AS MOUNT ROGERS...MAY EVEN TOY WITH TEMPERATURES IN THE 30S. FOR THE WEEKEND...INCREASING SUBSIDENCE IN THE WAKE OF THE UPPER LOW FAVORS MAINLY DRY CONDITIONS...ALTHOUGH CAN`T RULE OUT A POP-UP SHOWER IN THE MOUNTAINS. SINCE POPS LESS THAN 20 PERCENT...REMOVED SHOWER THREAT FOR ALL BUT THE WV HIGHLANDS. MODELS DO HINT AT ANOTHER FRONTAL ENCROACHMENT MONDAY, SO MAINTAINED CHANCE THREAT MONDAY. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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AS OF 745 AM EDT TUESDAY... POP UP SHOWERS WILL BE PRESENT THROUGHOUT THE REGION AT THE BEGINNING OF THE TAF PERIOD. MVFR CONDITIONS SHOULD BE EXPECTED FOR MOST IN HIGHER ELEVATIONS...VFR SHOULD BE PREDOMINANT FOR THE PIEDMONT. THUNDER THIS AFTERNOON CAN ALSO BE EXPECTED WITH SOME OF THESE SHOWERS. CONSIDERING THE AMOUNT OF PRECIP THAT HAS FALLEN LATELY...THERE WILL BE PLENTY OF AMBIENT MOISTURE IN THE AIR. THIS AND BELOW NORMAL LOWS EXPECTED TONIGHT...MOST ALL LOCATIONS WILL REACH THE CROSSOVER TEMP AND FOG CAN BE EXPECTED TO SETTLE INTO THE USUAL AREAS. AS OF THIS TIME CONFIDENCE IN JUST HOW MUCH VIS WILL BE RESTRICTED IS LOW...BUT SOME WILL MORE THAN LIKELY FALL TO IFR IN THE PRE-DAWN HOURS. AFTERWARDS...MOST WILL RETURN TO VFR WITH SOME MOUNTAINOUS AREAS MAINTAINING MVFR CONDS. EXTENDED AVIATION DISCUSSION... A DEEP LOW WILL MOVE SOUTHWARD FROM CANADA TOMORROW AND SETTLE OVER THE MID ATLANTIC FOR MUCH OF THE WEEK. CONDITIONS SHOULD BE EXPECTED TO BE MVFR OR WORSE FOR MUCH OF THE REMAINDER OF THE WEEK DUE TO PERIODIC SHOWERS...ISOLATED THUNDER...LOWS CIGS....AND FOG.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...RAB NEAR TERM...MBS/RAB SHORT TERM...PW LONG TERM...PM AVIATION...JR/RAB

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