Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 291155 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 755 AM EDT SAT AUG 29 2015 .SYNOPSIS...
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HIGH PRESSURE WILL REMAIN CENTERED OVER THE DELMARVA REGION FOR MUCH OF TODAY. A WEAK UPPER LEVEL DISTURBANCE WILL LIFT NORTH ALONG THE APPALACHIANS SUNDAY INTO MONDAY AHEAD OF A WEAK COLD FRONT TO THE WEST. UPPER LEVEL HIGH PRESSURE WILL STRENGTHEN IN THE WAKE OF THIS FEATURE...RESULTING IN MORE DIURNAL NATURE SHOWERS AND STORMS INTO THE MIDDLE OF NEXT WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 400 AM EDT SATURDAY... HIGH PRESSURE REMAINS CENTERED OVER THE DELMARVA REGION THIS MORNING...RESULTING IN SOUTH SOUTHEASTERLY WINDS FOR MUCH OF OUR AREA. NOT NEARLY AS MUCH COVERAGE OF LOW CLOUDS ACROSS THE MOUNTAINS COMPARED TO YESTERDAY...HOWEVER HIGH CLOUDS ARE MOVING IN FROM THE SOUTH AS AN UPPER LEVEL DISTURBANCE APPROACHES FROM THE GULF COAST REGION. FOR TODAY...INCREASING MOISTURE IN THE LOW LEVELS OF THE ATMOSPHERE WILL SUPPORT PARTLY CLOUDY SKIES...POSSIBLY BECOMING MOSTLY CLOUDY ACROSS THE MOUNTAINS DURING EARLY EVENING. INSTABILITY REMAINS LIMITED...HOWEVER MAY SEE A FEW SHOWERS DEVELOP FROM THE ALLEGHANY HIGHLANDS THROUGH THE MOUNTAIN EMPIRE. WITH SUBTROPICAL RIDGING NUDGING ITS WAY CLOSER TO THE MID ATLANTIC...WE CAN EXPECT SLIGHTLY WARMER TEMPERATURES FOR TODAY... WITH HIGHS RANGING FROM THE LOW 80S ACROSS THE MOUNTAINS...TO THE UPPER 80S ACROSS THE PIEDMONT. HIGH CLOUDS WILL INCREASE DURING THIS EVENING...MAKING FOR MOSTLY CLOUDY SKIES FOR TONIGHT. WARMER AND MUGGIER...OVERNIGHT LOWS WILL GENERALLY FALL INTO THE LOW TO MID 60S...WITH UPPER 50S FOR A FEW OF THE DEEPER VALLEYS ACROSS THE MOUNTAINS.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 230 AM EDT SATURDAY WATER VAPOR SATELLITE IMAGERY DEPICTS A BROAD UPPER LEVEL AREA OF LOW PRESSURE OVER THE NORTHERN GULF OF MEXICO WITH A PLUME OF MOISTURE IN ADVANCE OF THIS SYSTEM STREAMING INTO THE SOUTHEAST U.S. MOST OF THE DETERMINISTIC MODELS ARE IN GENERAL AGREEMENT THAT THIS LOW OPENS AND LIFTS INTO OUR AREA SUNDAY NIGHT/EARLY MONDAY BEFORE PUSHING EAST OF THE REGION BY LATE MONDAY...BEFORE UPPER HEIGHTS AND HIGHER PWAT VALUES BUILD TUESDAY. MODEL TRENDS HAVE BEEN SLIGHTLY SLOWER AND FURTHER WEST WITH THIS FEATURE. FOR SUNDAY...A WEAK UPPER LEVEL SHORTWAVE IN ADVANCE OF THE AFOREMENTIONED LOW ENTERS FAR SOUTHWEST VA ON SUNDAY. FORECAST SOUNDINGS STILL INDICATE A DRY LOW LEVEL ATMOSPHERE WITH LITTLE TO NO CAPE. KEPT A SMALL CHANCE FOR SHOWERS AND STORMS IN THE FAR WEST WHERE BEST UVM IS FORECAST ALONG WITH HIGHEST FORECAST THETA-E VALUES. NUDGED TEMPS DOWN A DEGREE OR TWO WITH THE EXPECTED INCREASED CLOUD COVER. BETTER CHANCE FOR PRECIPITATION APPEARS TO BE SUNDAY NIGHT WITH SURGE OF DEEPER MOISTURE AND BEST UPPER DYNAMICS ARRIVE. AS A RESULT...INCREASED POPS DURING THE OVERNIGHT HOURS SUNDAY NIGHT/MONDAY MORNING. IT SHOULD BE NOTICEABLY MORE HUMID MONDAY AND WARMER THANKS TO AN INCREASE IN 1000-850MB THICKNESSES...AND LEANED TOWARD THE WARM NAM MOS VALUES FOR HIGHS ON MONDAY. WHILE THE INITIAL UPPER LEVEL SHORT WAVE WILL BE EXITING OUR AREA DURING THE DAY...AND TAKING MOST OF THE PRECIPITATION WITH IT...LINGERING INSTABILITY AND WEAK LOW LEVEL CONVERGENCE IN THE MOUNTAINS SHOULD TRIGGER DIURNALLY DRIVEN WIDELY SCATTERED SHOWERS AND STORMS. PWAT VALUES CONTINUE TO SURGE TUESDAY AS AN UPPER RIDGE BUILDS... LEADING TO A HUMID AND WARM DAY WITH MORE AFTERNOON/EVENING SHOWERS AND STORMS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 1240 PM EDT FRIDAY... OVERALL PERSISTENCE FORECAST AT LEAST EARLY ON AS UPPER RIDGING STRENGTHENS ACROSS THE REGION IN THE WAKE OF THE PASSING WAVE ALOFT AND IN INCREASING SUBSIDENCE WELL NORTH OF ERIKA. THIS SHOULD RESULT IN A MORE DIURNALLY DRIVEN TREND OF DAILY SHOWERS AND ISOLATED STORMS EACH AFTERNOON/EVENING WITH A GRADUAL INCREASE IN COVERAGE/EXPANSE FROM TUESDAY THROUGH THURSDAY GIVEN BETTER PWATS/MOISTURE AND SLIGHT COOLING ALOFT. HOWEVER THINK LOW/MEDIUM CHANCE POPS CONFINED MAINLY ALONG/WEST OF THE BLUE RIDGE PER OROGRAPHICS...AND MORE ISOLATED ELSEWHERE ESPECIALLY GIVEN MOISTURE OVER TOP A LINGERING SURFACE RIDGE. THUS FOLLOWED CLOSER TO TRENDS FROM WPC WITH A GRADUAL BOOST IN POPS EACH DAY BUT LITTLE DURING THE OVERNIGHTS INTO THURSDAY. THINGS BECOME MORE UNCERTAIN BY DAY7 WITH MODELS LOWERING HEIGHTS ACROSS THE APPALACHIANS AND FROM THE NE WITH A POSSIBLE ASSOCIATED BACKDOOR COOL FRONT. THIS COULD HELP FOCUS MOISTURE GIVEN A BETTER EASTERLY TRAJECTORY TO THE NORTH OF ERIKA OR ITS REMNANTS ON FRIDAY. THEREFORE GOING WITH MORE WIDESPREAD CHANCE POPS PER POTENTIAL TROPICAL TYPE PWATS OVER THE AREA DURING HEATING FRIDAY AFTERNOON. OTHERWISE LITTLE CHANGE IN DAILY TEMPS GIVEN SUCH A HUMID/WARM AIRMASS...SUPPORTING HIGHS MOSTLY IN THE 80S AND LOWS IN THE 60S EXCEPT PERHAPS A BIT COOLER FRIDAY PENDING CLOUDS/SHOWERS. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
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AS OF 745 AM EDT SATURDAY... HIGH PRESSURE REMAINS CENTERED OVER THE DELMARVA THIS MORNING... MAINTAINING LIGHT SOUTH SOUTHEASTERLY WINDFLOW ACROSS THE AREA. LOW LEVEL MOISTURE IS GRADUALLY INCREASING AS THIS WINDFLOW DRAWS ATLANTIC AIR UPSLOPE INTO THE MOUNTAINS...WHICH HAS RESULTED IN MORE WIDESPREAD REPORTS OF MAINLY FG/BR ACROSS THE AREA COMPARED TO PREVIOUS MORNINGS. SURFACE OBSERVATIONS ACROSS THE MOUNTAINS AND FOOTHILLS HAVE DETECTED SCATTERED CEILINGS IN THE 5KFT TO 8KFT RANGE. FOG WILL BURN OFF QUICKLY AFTER 29/14Z WITH DAYTIME HEATING... RESULTING IN VFR CONDITIONS AREAWIDE. INCREASING MOISTURE WILL MAKE FOR A SCT CU FIELD DEVELOPING LATE MORNING...POSSIBLY BECOMING BKN ACROSS THE MOUNTAINS DURING LATE AFTERNOON...WITH CEILING BASES 5KFT TO 8KFT. INSTABILITY IS LIMITED...BUT MAY BE SUFFICIENT TO TRIGGER ISOLATED SHOWERS ACROSS SOUTHEAST WEST VIRGINIA...POSSIBLY AS FAR EAST AS KBCB. EVEN THEN...SHOWER THREAT IS NOT EXPECTED TO RESULT IN SUB VFR CONDITIONS WHERE THEY OCCUR FOR MORE THAN A FEW MINUTES. CONVECTION WILL WANE TOWARD SUNSET. WITH INCREASING UPPER LEVEL CLOUDS DURING LATE SATURDAY EVENING... EXPECT REDEVELOPMENT OF FG/BR WILL BE MORE ON THE PATCHY SIDE. REGARDLESS...RIVER VALLEY FOG WILL BE LOCALLY DENSE...PUSHING VISIBILITIES TO 1/4SM OR LESS IN SPOTS. SCATTERED LOW CLOUDS WILL ALSO REMAIN ACROSS THE MOUNTAINS AND FOOTHILLS...WITH BASES IN THE 4KFT TO 6KFT RANGE...BUT POSSIBLY HIGH END MVFR IN SPOTS. EXTENDED AVIATION DISCUSSION... SHORT WAVE ENERGY MOVING UP FROM THE SOUTH WILL SUPPORT AN INCREASED CHANCE FOR CONVECTIVE ACTIVITY IN THE SUNDAY/MONDAY TIME FRAME. GENERALLY EXPECT THE BEST CHANCES FOR MVFR/IFR TO BE LATE NIGHT/EARLY MORNING DUE TO FOG AND STRATUS DEVELOPMENT FROM THE BLUE RIDGE WEST ESPECIALLY AT KLWB/KBCB.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...NF NEAR TERM...NF/WP SHORT TERM...PH LONG TERM...JH AVIATION...NF/WP

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