Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 280610 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 210 AM EDT THU MAY 28 2015 .SYNOPSIS... HIGH PRESSURE OFF THE SOUTHEAST COAST WILL MAINTAIN A BROAD SOUTHERLY FLOW OF MOISTURE INTO THE REGION THROUGH THE REMAINDER OF THIS WEEK. A WEAK UPPER LEVEL DISTURBANCE AND ASSOCIATED FRONTAL BOUNDARY WILL SLIDE INTO THE REGION EARLY THURSDAY. THIS WEATHER FEATURE IN COMBINATION WITH DAYTIME HEATING AND INSTABILITY WILL RESULT IN PERIODIC ROUNDS OF SHOWERS AND STORMS OVER THE NEXT FEW DAYS. && .NEAR TERM /THROUGH TODAY/... AS OF 926 PM EDT WEDNESDAY... SHOWERS AND THUNDERSTORMS LOCATED TO OUR SOUTHEAST FROM RALEIGH NORTH CAROLINA TO EMPORIA VIRGINIA WHICH DEVELOPED ALONG OUTFLOW BOUNDARIES AND IN THE AREAS OF RICHER CAPE ABOVE 1K AND STRONG THETAE/ADVECTION ARE MOVING NORTHEAST AND WILL MISS THE EASTERN COUNTIES OF OUR FORECAST AREA DURING THE NEXT HOUR OR TWO. ISOLATED SHOWERS HAVE FORMED IN THE WESTERN MOUNTAINS AND ENDED QUICKLY WITH THE MORE STABLE AIR. WE WILL HAVE TO WATCH NEXT COUPLE OF HOURS TO SEE IF ANY CONVECTION TO OUR WEST IN EASTERN TENNESSEE AND KENTUCKY SURVIVES ITS MARCH EASTWARD INTO THE STABLE AIR ACROSS THE WESTERN MOUNTAINS. HOWEVER...WITH THE LOSS OF SOLAR HEATING MOST OF THE CONVECTION WILL WEAKEN AND DISSIPATE THIS EVENING INTO TONIGHT. UNDER PARTLY CLOUDY SKIES EXPECT ANOTHER MILD OVERNIGHT WITH LOW TEMPERATURES FROM THE UPPER 50S IN THE MOUNTAINS TO THE MID 60S IN THE PIEDMONT. LINGERING BOUNDARIES AND MCVS FROM UPSTREAM CONVECTION SHOULD PROVIDE FOR BETTER COVERAGE OF CONVECTION THURSDAY AFTERNOON. THE SWODY2 (CONVECTIVE OUTLOOK DAY 2 FOR SEVERE POTENTIAL) KEEPS OUR AREA IN THE GENERAL THUNDERSTORMS. WITH WEAK STEERING FLOW AND WELL ABOVE AVERAGE PRECIP WATER VALUES EXPECTED...LOCALLY HEAVY RAIN WILL BE POSSIBLE WITH TRAINING OR STORMS LOCKED ON TERRAIN. HIGH TEMPERATURES WILL RANGE FROM THE MID 70S IN THE MOUNTAINS TO THE UPPER 80S IN THE PIEDMONT. AS OF 630 PM EDT WEDNESDAY... MADE SOME ADJUSTMENTS TO POPS FOR THIS EVENING INTO TONIGHT. USED A BLEND OF HRRR AND RNK WRFARW. DRIER AIR PUSHING IN FROM THE WEST...WAS HINDERING THUNDERSTORM DEVELOPMENT. GIVEN LIMITED INSTABILITY EXPECTED CONVECTION TO DIMINISH WITH THE LOSS OF SOLAR HEATING THIS EVENING. LOW TEMPERATURES WILL BE MILD OVERNIGHT WITH READINGS FROM AROUND 60 DEGREES IN THE MOUNTAINS TO THE MID 60S IN THE PIEDMONT. AS OF 350 PM EDT WEDNESDAY... CONVECTION STRUGGLING TO GET GOING SO FAR THIS AFTERNOON AND WILL LIKELY REMAIN ISOLATED THROUGH THIS EVENING...MAINLY IN MTNS AND FOOTHILLS...GIVEN LIMITED INSTABILITY AND DRIER AIR PUSHING IN FROM THE WEST BEHIND THE WEAK SHORT WAVE THAT HAS LIFTED NORTHEAST OVER THE NORTHEAST U.S. ANY WIDELY SCATTERED CONVECTION THAT DOES MANAGE TO DEVELOP THE REMAINDER OF THE AFTERNOON SHOULD DIMINISH QUICKLY WITH LOSS OF HEATING. WILL NEED KEEP AN EYE ON MORE ORGANIZED CONVECTION WELL TO THE WEST AS IT MOVES INTO EASTERN KY AND TN...BUT ALL INDICATIONS ARE THAT THIS WILL DIE QUICKLY WELL BEFORE IT REACHES WESTERN SLOPES OF APPALACHIANS...WHICH WOULD BE NEAR MIDNIGHT IF IT DID SURVIVE. KEEPING A SLIGHT CHANCE POP IN THE WEST FOR THIS SMALL POSSIBILITY... AS WELL AS ALONG BLUE RIDGE MAINLY IN NW NC GIVEN SOME LINGERING INSTABILITY AND CONVERGENCE PER THE HRRR...BUT OTHERWISE DROPPING POPS AFTER MIDNIGHT. SOME SUGGESTION IN THE GUIDANCE THAT PATCHY FOG MAY BE MORE LIKELY LATE TONIGHT...BUT WITH GENERAL LACK OF RAINFALL EXPECTED REMAINDER OF THE DAY...AND SOME RESIDUAL MID DECK OVERNIGHT...THINK THIS IS NOT LIKELY AND HAVE CHOSEN NOT TO INCLUDE IT. FOR THURSDAY...WE FINALLY HAVE SOME INGREDIENTS COMING TOGETHER TO SUPPORT MORE WIDESPREAD COVERAGE OF CONVECTION...WITH WEAK UPPER WAVE MOVING INTO APPALACHIANS EARLY IN THE DAY AND ASSOCIATED WEAK FRONTAL BOUNDARY...OR REALLY MORE OF A TROUGH AXIS...WHICH WILL ADD TO SOME WEAK CONVERGENCE ALREADY GEOGRAPHICALLY FAVORED NEAR THE BLUE RIDGE. MODELS SUGGEST MODEST INSTABILITY IN PART BECAUSE OF WARMER AFTERNOON TEMPS EXPECTED...BUT STILL NOTHING SUPER IMPRESSIVE...AND PERHAPS ENOUGH DRY AIR AT MID LEVELS TO SUPPORT SOME GUSTY DOWNDRAFTS. AT THIS POINT THINK SEVERE POTENTIAL IS LIMITED...BUT MUCH BETTER THAN THE LAST COUPLE OF DAYS. HOWEVER WITH WEAKER STEERING FLOW AND WELL ABOVE AVERAGE PRECIP WATER VALUES EXPECTED...LOCALLY HEAVY RAIN WILL BE THE MAIN CONCERN. GIVEN DRY ANTECEDENT CONDITIONS...NOT ALL THAT CONCERNED ABOUT A FLASH FLOOD THREAT...BUT STILL SOMETHING TO KEEP AN EYE ON WITH ISOLATED AREAS IF ANY STORMS BECOME LOCKED ON TERRAIN. THIS WILL STILL MAINLY BE OVER THE MOUNTAINS...WITH COVERAGE JUSTIFYING SOME LIKELY POPS...BUT STORMS MAY DRIFT INTO THE PIEDMONT BY LATE AFTERNOON...SO MID CHANCE POPS BY LATE IN THE DAY THERE AS WELL. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... AS OF 330 PM EDT WEDNESDAY... UPPER PATTERN WILL BE IN TRANSITION DURING THE SHORT TERM WITH FLATTENING OF THE EAST COAST RIDGE AND A TROF DEVELOPING INTO A CLOSED LOW OVER THE MISSISSIPPI VALLEY. THIS WILL KEEP US IN A WEAKLY FORCED WARM/MOIST/UNSTABLE ENVIRONMENT WITH A DIURNAL TREND AND MOUNTAIN BIAS FOR SHOWERS/THUNDERSTORMS. A WEAK COLD FRONT WILL BE APPROACHING FROM THE NORTHWEST BY THE WEEKEND BUT UNCERTAINTY WILL BE INCREASING AS GUIDANCE DIFFERS IN HANDLING THE SPEED OF THIS FEATURE. BELIEVE THE SCENARIO WILL LEAD TO INCREASING CHANCES FOR FOR CONVECTION DURING THE LATTER PORTION OF THE WEEKEND. BIGGEST CONCERN WILL BE THE POSSIBILITY OF LOCALLY HEAVY RAIN GIVEN PRECIPITABLE WATER VALUES OF 1.0 TO 1.5 INCHES ACROSS THE REGION. TEMPERATURES WILL REMAIN ABOVE NORMAL WITH READINGS TRENDING UP A FEW DEGREES THROUGH THE WEEKEND... GENERALLY LOOKING FOR MID/UPPER 80S EAST OF THE BLUE RIDGE LOWER 80S WEST WITH THE USUAL COOLER READINGS AT THE HIGHER ELEVATIONS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 330 PM EDT WEDNESDAY... BY SUNDAY NIGHT THE UPPER PATTERN WILL BE WELL ON ITS WAY TO DEVELOPING A SPLIT FLOW REGIME ACROSS THE NORTHERN TIER OF STATES AS A CLOSED LOW DEVELOPS OVER THE MISSISSIPPI VALLEY AND SLOWLY SINKS SOUTHWARD THROUGH THE MIDDLE OF NEXT WEEK. SOME RIDGING WILL ALSO BE TAKING PLACE OVER THE MID ATLANTIC REGION AND SET UP A SLUGGISH BLOCKY PATTERN. AT THE SURFACE HIGH PRESSURE WILL BUILD THROUGH THE NORTHEAST AND WEDGE DOWN THE EASTERN SEABOARD...BRINGING COOLER/NEAR NORMAL TEMPERATURES TO THE REGION. HOWEVER...THE PATTERN WILL KEEP US MOIST WITH DEEP SOUTHEASTERLY FLOW AND EXPECT ENOUGH FORCING BETWEEN OROGRAPHIC UPSLOPE AND DIURNAL EFFECTS TO KEEP SOME SHOWER ACTIVITY...AND POSSIBLY A THUNDERSTORM... IN THE FORECAST THROUGH THE PERIOD. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 200 AM EDT THURSDAY... PATCHY FOG THIS MORNING...OTHERWISE VFR ANTICIPATED THROUGH FIRST HALF OF THE DAY THURSDAY. DAYTIME HEATING...IN ADDITION TO SOME LIFT FROM APPROACHING FRONT OVER THE OHIO VALLEY AND VORTICITY ASSOCIATED WITH CONVECTIVE DEBRIS MOVING NORTH FROM THE SOUTHERN APPALACHIANS...SHOULD RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS DURING THE MID/LATE AFTERNOON AND EVENING. MESOSCALE MODELS FOCUS THE GREATEST COVERAGE BETWEEN 20Z/3PM AND 01Z/9PM...AND MAINLY ACROSS THE MOUNTAINS ALONG AND WEST OF THE BLUE RIDGE. MEAN WINDS FROM SFC-20KFT ARE FCST TO BE LESS THAN 10 KTS...SO SHOWERS/STORMS THAT DEVELOP SHOULD BE SLOW MOVING. SURFACE WINDS THROUGH THE TAF VALID PERIOD WILL BE LIGHT AND VARIABLE...SPEEDS MOSTLY 7KTS OR LESS. EXTENDED AVIATION DISCUSSION... THROUGH THE UPCOMING WEEKEND...A MOIST UNSTABLE AIR MASS WILL REMAIN IN PLACE ACROSS THE REGION WITH ONLY WEAK FORCING. THIS WILL RESULT IN MAINLY SLOW MOVING DIURNALLY DRIVE DEEP CONVECTION DURING THE AFTERNOON AND EVENING HOURS FOLLOWED BY STABLE CONDITIONS AT NIGHT. A FRONTAL SYSTEM WILL APPROACH FROM THE NORTH DURING THE WEEKEND...BUT WILL LIKELY REMAIN WELL NORTH OF THE FORECAST AREA THROUGH SUNDAY. THUS...NO CHANGE IN AIR MASS IS EXPECTED THROUGH THE PERIOD. WITH MOIST/STABLE CONDITIONS AT NIGHT...PATCHY LATE NIGHT/EARLY MORNING LOW CLOUDS/FOG AND ASSOCIATED IFR-LIFR CIGS/VSBYS WILL BE POSSIBLE EACH MORNING...BUT LIMITED TO A FEW HOURS BEFORE DAYBREAK AND QUICKLY BURNING OFF AFTER SUNRISE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PM/SK NEAR TERM...KK/SK SHORT TERM...MBS LONG TERM...MBS AVIATION...PM

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