Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 310046 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 846 PM EDT SAT MAY 30 2015 .SYNOPSIS...
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HIGH PRESSURE OFFSHORE WILL MAINTAIN A WARM AND HUMID AIRMASS ACROSS THE REGION INTO SUNDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST LATE IN THE WEEKEND...BEFORE PUSHING SOUTH OF THE AREA MONDAY INTO MONDAY NIGHT...RESULTING IN AN INCREASING THREAT FOR SHOWERS AND THUNDERSTORMS LATER SUNDAY INTO MONDAY AFTERNOON. COOLER WEATHER WILL BUILD IN BY THE MIDDLE OF NEXT WEEK.
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&& .NEAR TERM /THROUGH SUNDAY/...
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AS OF 840 PM EDT SATURDAY... HAVE ISSUED UPDATE TO GRIDS FOR OVERNIGHT PERIOD TO REMOVE ALL MENTION OF SHOWERS/THUNDERSTORMS BASED ON LATEST RADAR AND SATELLITE TRENDS...SPC MESOANALYSIS...AND HRRR AND LOCAL WRF MODEL RUNS. CORFIDI VECTORS AND BEST THETA-E AXIS AND THETA-E ADVECTION FORECAST TO REMAIN NORTHWEST OF THE BLACKSBURG FORECAST AREA FOR MUCH OF THE REST OF THE NIGHT...WITH ANY POSSIBILITY FOR FOLD-OVER SHOWERS BACK INTO SE WV COUNTIES NOT LIKELY TO OCCUR UNTIL AROUND DAYBREAK...OR LATER. ALSO A SLIGHT HINT IN SOME OF THE MESOSCALE MODELS OF EASING DEGREE OF CURRENT SUBSIDENCE AND RETURN OF SOME MID LEVEL MOISTURE INTO NORTH CENTRAL NC INTO SOUTHSIDE VA TOWARD DAYBREAK...WHICH MIGHT PRECLUDE A MINIMAL THREAT OF SOME ISOLATED/WIDELY SCATTERED SHOWERS TOWARD DAYBREAK...BUT WILL NOT INTRODUCE IN FORECAST UNTIL DEVELOPMENT ACTUALLY BEGINS TO OUR SOUTH (IF AT ALL) CONSIDERING HOW BULLISH MODELS HAVE BEEN RECENTLY IN GENERATING CONVECTION THAT NOES NOT MATERIALIZE. REGARDLESS...MOST OF EVENING/OVERNIGHT PERIOD WILL BE DRY IN ALL AREAS...SO REMOVAL OF THREAT FOR ALL AREAS FOR REST OF THE EVENING AND FOR MUCH OF THE OVERNIGHT PERIOD SEEMED WARRANTED. OTHERWISE...NO ADDITIONAL CHANGES NEEDED TO EXISTING SET OF GRIDS AT THE PRESENT TIME OTHER THAN TO TWEAK/LOWER FORECAST CLOUD COVER. HOURLY TEMPERATURE/DEW POINT TRENDS STILL VERIFYING REMARKABLY WELL AND DO NOT REQUIRE MODIFICATION. AS OF 250 PM EDT SATURDAY... FOG WILL AGAIN FORM TONIGHT IN LOCATION THAT HAD RAIN SATURDAY AFTERNOON AND EVENING. PATCHY DENSE FOG IS POSSIBLE NEAR AREA RIVERS AND LAKES AS LONG AS THERE IS SOME PROLONGED CLEARING OVERNIGHT. LOW PRESSURE WILL BE OVER THE OHIO VALLEY ON SUNDAY MORNING WITH A COLD FRONT TRAILING FROM THE LOW INTO THE LOWER MISSISSIPPI VALLEY. LOW LEVEL WINDS WILL BACK TO THE SOUTHEAST IN RESPONSE TO THIS SYSTEM WHICH WILL ENHANCE CONVERGENCE ALONG THE BLUE RIDGE. EXPECT THE HIGHEST PROBABILITY OF SHOWERS AND THUNDERSTORMS ALONG THE BLUE RIDGE AND IN THE EXTREME WESTERN COUNTY WARNING AREA SUNDAY AFTERNOON. ASIDE FROM DAYTIME HEATING AND INSTABILITY...NOT MUCH OTHER LIFT OR SUPPORT FOR ANY ORGANIZED THUNDERSTORMS OR EXPANDED COVERAGE THROUGH LATE SUNDAY. NO CHANGE IN AIR MASS TONIGHT OR SUNDAY. MINIMUM AND MAXIMUM TEMPERATURES WILL REMAIN 5 TO 10 DEGREES ABOVE NORMAL.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... AS OF 330 PM EDT SATURDAY A COLD FRONT SITUATED NEAR THE OHIO RIVER AROUND SUNSET SUNDAY WILL MAKE ONLY SLIGHT PROGRESS TOWARD OUR AREA THROUGH THE NIGHT. WITH LOSS OF HEATING AND MINIMAL UPPER SUPPORT...HAVE LOWERED RAIN CHANCES TO SLIGHT CHANCE WORDING BY DAWN MONDAY. WIDESPREAD CLOUD COVER WILL HELP MAINTAIN OVERNIGHT TEMPERATURES IN THE LOW TO MID 60S AREAWIDE. WEATHER FORECAST MODELS HAVE TRENDED SLOWER WITH THE APPROACH OF THE COLD FRONT ON MONDAY...DELAYING ITS ARRIVAL INTO THE WESTERN HALF OF OUR AREA UNTIL MONDAY NIGHT. REGARDLESS...STILL ANTICIPATE SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE FORECAST AREA AS THE SUPPORTING UPPER LEVEL TROUGH PASSES NORTH OF OUR AREA...WHILE STRONG HEATING AHEAD OF THE FRONT WILL ADD INSTABILITY TO THE LOW LEVELS. EXPECT TO SEE A FEW STRONG STORMS DURING THE AFTERNOON AND EVENING...AS WELL AS THE POTENTIAL FOR LOCALLY HEAVY RAIN DUE TO SLOW STORM MOVEMENT. THE COLD FRONT WILL CONTINUE TO DRIFT EAST ACROSS OUR AREA ON TUESDAY...ALTHOUGH THE TRULY DRIER AIR BEHIND THE FRONT WILL BE SLOW TO ARRIVE. AS SUCH...WILL MAINTAIN A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE FORECAST...MORE SO ACROSS THE PIEDMONT WHERE THE FRONT WILL BE SITUATED. HIGH PRESSURE WILL PASS FROM THE GREAT LAKES TUESDAY NIGHT TOWARD NEW ENGLAND AND THE MID ATLANTIC... HELPING TO PUSH THE FRONT FURTHER SOUTH AS THE HIGH WEDGES AGAINST THE EASTERN FACE OF THE APPALACHIANS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 330 PM EDT SATURDAY... HIGH PRESSURE WILL REMAIN WEDGED AGAINST THE APPALACHIANS THROUGH THE LATER HALF OF THE COMING WORKWEEK...MAINTAINING AN EAST TO SOUTHEASTERLY WIND FLOW ACROSS OUR AREA. WITH AN UPPER LEVEL LOW SPINNING ACROSS THE LOWER MISSISSIPPI VALLEY...AND LIGHT SOUTHWESTERLY FLOW ALOFT PUSHING ALONG THE CENTRAL APPALACHIAN CHAIN...DO NOT SEE THE COLD FRONT SINKING VERY FAR AWAY FROM OUR AREA...PERHAPS STALLING ACROSS CENTRAL NORTH CAROLINA. AS SUCH... WILL MAINTAIN A CHANCE FOR SHOWERS AND THUNDERSTORMS EACH DAY ACROSS OUR AREA...WILL BETTER RAIN CHANCES ACROSS THE MOUNTAINS WEST OF INTERSTATE 77...AS WELL AS OVER THE NORTH CAROLINA PIEDMONT. INSTABILITY WILL BE MORE ON THE MARGINAL SIDE...SO BELIEVE THE POTENTIAL FOR ANY STRONG THUNDERSTORMS WILL BE LOW...BUT WITH PLENTY OF DEEP MOISTURE FLOWING NORTH ALONG THE APPALACHIAN CHAIN...WILL HAVE WATCH FOR AREAS OF LOCALLY HEAVY RAIN EACH AFTERNOON AND EVENING. EXPECT TEMPERATURES TO BE NEAR NORMAL FOR EARLY JUNE AREAWIDE. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... AS OF 755 PM EDT SATURDAY... MAINLY VFR CONDITIONS WITH NO RESTRICTIONS EXPECTED OVERNIGHT WITH MOST...IF NOT ALL...WIDELY SCATTERED SHOWERS/THUNDERSTORMS EXPECTED TO REMAIN TO THE SOUTH OR TO THE NORTHWEST OF THE TERMINAL FORECAST AREA BASED ON LATEST HIGHER RESOLUTION MODEL FORECASTS. WITH GOOD DAYTIME HEATING AND DRYING TODAY...DO NOT EXPECT TO SEE SIGNIFICANT REDEVELOPMENT OF FOG LATER TONIGHT EXCLUDING LOW LYING SHELTERED AREAS AND RIVER VALLEYS. THEREFORE...WILL CONTINUE TO INCLUDE A BRIEF INTRUSION OF VISIBILITY INTO MVFR RANGE TOWARD DAYBREAK IN CLIMATOLOGICALLY FAVORED AREAS...SUCH AS AT KBCB...KLWB...AND KLYH...AND WILL ALSO INCLUDE AT KDAN PER LATEST LAMP GUIDANCE. SIMILAR TO SATURDAY MORNING...FOG EXPECTED TO BE SHALLOW AND DISSIPATE BY 13-14Z/09-10AM SUNDAY. COLD FRONT WILL TRAIL ACROSS THE OHIO VALLEY ON SUNDAY. ONCE AGAIN STORMS WILL DEVELOP BETWEEN 16Z-18Z/NOON-2PM...WITH GREATEST THREAT IN THE MOUNTAINS AND FOOTHILLS. THEREFORE INCLUDED VCTS IN TERMINAL FORECAST TEXT AT KBLF...KLWB...KBCB...AND KROA...BUT NOT FURTHER EAST AT KLYH OR KDAN. EXTENDED DISCUSSION... THE SLOWLY APPROACHING COLD FRONT EXPECTED TO SINK SOUTH INTO THE REGION ON MONDAY RESULTING IN EVEN HIGHER THREAT OF CONVECTIVE ACTIVITY...ESPECIALLY FROM THE BLUE RIDGE EAST...WITH THREAT PERSISTING INTO AT LEAST MONDAY NIGHT BEFORE THE BOUNDARY SINKS FURTHER SOUTH. THIS SHOULD MAKE FOR MORE FREQUENT PERIODS OF SUB- VFR INTO TUESDAY WITH LOWER CIGS/VSBY REDUCTIONS DUE TO SHOWERS/STORMS BY DAY...AND IN PATCHY FOG EARLY MORNING FOG. LOWER MVFR/IFR CIGS ARE LIKELY BEHIND THE FRONT WEDNESDAY INTO THURSDAY...DUE TO PERSISTENT POST-FRONTAL EASTERLY FLOW AND COOL/MOIST AIR WEDGING. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS/WERT NEAR TERM...AMS/WERT SHORT TERM...NF LONG TERM...NF AVIATION...AMS/JH/WERT

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