Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 030916 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 516 AM EDT TUE MAY 3 2016 .SYNOPSIS...
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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.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 430 AM EDT TUESDAY... UNSETTLED WEATHER PATTERN TO CONTINUE...BUT SEVERE THREAT AND FLOODING THREAT GREATLY DIMINISHED. SLOW MOVING FRONTAL SYSTEM THAT BROUGHT WIDESPREAD SEVERE WEATHER TO THE REGION MONDAY EVENING DRAPED ACROSS THE REGION FROM NEAR KDCA...TO KDAN...TO KCLT EARLY THIS MORNING. SHOWERS CONTINUE ALONG THE FRONT THIS MORNING...WITH A NEW AREA OF RAIN SHOWERS SPREADING INTO THE REGION FROM THE OH/TN VALLEY. NOTHING TO THE DEGREE OBSERVED PRIOR TO MIDNIGHT...NOR IS ANY SUCH REPEAT EXPECTED TODAY. HAVE NOT OBSERVED ANY LIGHTNING SINCE ABOUT 06Z. RAINFALL AMOUNTS NOW GENERALLY IN THE 1/4 INCH OR LESS CATEGORY...WITH THE HEAVIEST NOW MAINLY S-SE OF THE RNK CWA. 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.
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&& .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
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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.
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&& .LONG TERM /SATURDAY THROUGH MONDAY/...
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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.
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&& .AVIATION /09Z TUESDAY THROUGH SATURDAY/... AS OF 140 AM EDT TUESDAY... A COLD FRONT IS SLOWLY PUSHING THROUGH THE MID ATLANTIC TONIGHT. RAIN SHOWERS WILL CONTINUE AT KLYH AND KDAN FOR THE NEXT SEVERAL HOURS. MOST TAF SITES ARE AT VFR NOW...BUT IT WILL NOT LAST AS ANY CLEARING FROM THE RAIN COULD LEAD TO LOW CLOUDS AND PATCHY FOG. SOME IFR/MVFR CONDITIONS ARE POSSIBLE ACROSS THE ENTIRE AREA...BUT CONFIDENCE ON THE TIMING AND INTENSITY OF THE DETERIORIATING FLYING WEATHER IS QUESTIONABLE. TO ACCOUNT FOR THE VARIABILITY OF CONDITIONS TONIGHT...TEMPO GROUPS WERE ADDED FOR LOWER CEILINGS AND VISIBILITIES AT ALL TAF SITES DURING THE REST OF THE NIGHT. BY TUESDAY MORNING...CONDITIONS WILL SLOWLY IMPROVE WEST OF THE BLUE RIDGE TO MVFR...WHILE THE PIEDMONT MAY REACH VFR FASTER. THE COLD FRONT SLOWLY REACHES THE EAST COAST...AND BRINGS MORE SHOWERS FOR KLYH AND KDAN DURING THE AFTERNOON. INSTABILITY IS CERTAINLY MUCH WEAKER ON TUESDAY COMPARED TO MONDAY...WHICH RESULTS IN THUNDER BEING LEFT OUT OF THESE TAFS DUE TO LOWER CONFIDENCE. MEANWHILE...AN UPSLOPE NORTHWEST FLOW OVER THE MOUNTAINS COULD BRING SCATTERED SHOWERS FOR KBLF AND KLWB BY THE AFTERNOON...BUT THESE SHOWERS SHOULD NOT IMPEDE CONDITIONS TOO MUCH. EXTENDED AVIATION DISCUSSION... THE COLD FRONT DEPARTS OFFSHORE ON TUESDAY NIGHT...WHICH WILL ALLOW ALL TAF SITES TO RETURN TO VFR. HOWEVER...A DEEP UPPER LEVEL LOW FROM THE HUDSON BAY IN CANADA...SHOULD DIVE SOUTHWARD TOWARD THE MID ATLANTIC ON WEDNESDAY. THIS UPPER LEVEL LOW SETTLES OVER THE MID ATLANTIC THROUGH THE REMAINDER OF THIS WEEK. FLYING CONDITIONS SHOULD REMAIN RATHER POOR DURING THIS TIME DUE TO PERIODIC SHOWERS...LOW CEILINGS...AND PATCHY FOG. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...RAB NEAR TERM...RAB SHORT TERM...PW LONG TERM...PM AVIATION...PW

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