Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 111759 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 159 PM EDT FRI JUL 11 2014 .SYNOPSIS... WEAK HIGH PRESSURE WILL SPILL SOUTH INTO THE REGION TODAY AND CONTINUE TO EXTEND INTO THE AREA FROM OFF THE MID ATLANTIC COAST INTO SATURDAY. DEEPER MOISTURE WILL RETURN LATER SUNDAY INTO EARLY NEXT WEEK AHEAD OF A STRONG COLD FRONT THAT WILL BE PASSING THROUGH THE REGION TUESDAY INTO TUESDAY NIGHT. HIGH PRESSURE FOLLOWING THE FRONT SHOULD BRING MUCH DRIER AND COOLER AIR FOR THE MIDDLE AND END OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 152 PM EDT FRIDAY... MINOR ADJUSTMENT TO HIGH TEMPS ACROSS PARTS OF THE WEST...ESPECIALLY GREENBRIER VALLEY WHICH HAS ALREADY REACHED FCST HIGH OF LOW 80S. DEW PTS ALSO MIXING OUT MORE IN THE WEST THAN IN THE EAST...AND ADJUSTED ACCORDINGLY. VERY ISOLD SHWRS POPPING UP ALONG BLUE RIDGE BUT STRUGGLING AS UPDRAFTS MIX IN WITH DRIER AIR...AND MADE SOME VERY MINOR ADJUSTMENTS FOR REMAINDER OF AFTERNOON TO POPS AND SKY COVER BASED ON LATEST OBSERVATIONS. PREV DISCUSSION AS OF 1055 AM EDT FRIDAY... MORNING SOUNDINGS SUPPORT CURRENT FORECAST HIGH TEMPERATURES WITH GOOD MIXING EXPECTED...BUT VERY WEAK WINDS TO MIX DOWN AS WELL. PLENTY OF MID LEVEL DRY AIR...MUCH MORE SO AT RNK COMPARED TO GSO WHICH MATCHES WATER VAPOR IMAGERY ADN EXPECT CONTINUED DRYING IN PIEDMONT REST OF TODAY AT THOSE LEVELS. SUBSIDENCE INVERSION IS ALSO FAIRLY STRONG SO ANY CONVECTION TRYIN TO DEVELOP ACROSS HIGHER TERRAIN THIS AFTERNOON WILL HAVE A HARD TIME FIGHTING THROUGH THIS DRY AIR. WAS TEMPTED TO DROP POPS DOWN ANOTHER NOTCH AND ONLY HAVE SLIGHT CHC OVER NW NC MTNS...BUT BETWEEN LIGHT SE FLOW ALONG BLUE RIDGE AND HIGH RES CONVECTIVE ALLOWING MODELS SUGGESTING A VARIETY OF COVERAGE IN THE MTNS AND FOOTHILLS FROM NEARLY NOTHING TO SOMETHING THAT WOULD STILL SUPPORT A HIGH CHC. DECIDED TO LEAVE AS IS WITH MAINLY ISOLD COVERAGE...BUT ANY CELLS MAY HAVE LITTLE IF ANY THUNDER. ONLY LOW CHC POPS REMAIN IN NW NC MTNS. MOST PLACES WILL REMAIN DRY HOWEVER. OTHERWISE...SOME ADDITIONAL TWEAKS FOR SKY COVER AND DEW PTS FOR REST OF THE AFTERNOON...BUT NOTHING SIGNIFICANT. PREV DISCUSSION AS OF 900 AM EDT FRIDAY... VERY MINOR UPDATE TO HOURLY GRIDS TO LINGER SOME FOG IN MTN VALLEYS JUST A BIT LONGER AND BETTER MATCH CURRENT AREAS INTO SHENANDOAH VALLEY...AND ALSO ADJUST SKY COVER TO BETTER MATCH OBS AND MORE CLEARING THIS MORNING BEFORE CU FILL BACK IN MIDDAY. OTHERWISE NO OTHER CHANGES AT THIS TIME AS MEX TEMP AND GENERALLY SLIGHT CHC PRECIP FOR HIGHER TERRAIN STILL LOOKS GOOD. PREV DISCUSSION AS OF 240 AM EDT FRIDAY... FAINT SURFACE FRONT BASICALLY REMAINS EAST-WEST ALONG THE HIGHWAY 460 CORRIDOR ATTM AS MOST SHOWERS HAVE FADED PER LOSS OF INSTABILITY AND ARRIVAL OF DRIER AIR ALOFT SEEN OFF THE LATEST VAPOR LOOP. HOWEVER WITH DEEPER MOISTURE STILL SOUTH OF THE BOUNDARY AND MSAS SHOWING LINGERING HIGHER THETA-E...WILL LEAVE IN A TOKEN POP ACROSS THE SE EARLY THIS MORNING GIVEN OUTFLOW AROUND. OTRW FRONT TO SLIDE A BIT MORE TO THE SE TODAY AS MORE OF THE DRIER AIR ALOFT TO THE NW ARRIVES IN THE WAKE OF THE PASSING 5H TROF AXIS JUST OFF TO THE EAST. THIS ALONG WITH SLIGHTLY LOWER DEWPOINTS/PWATS...AND LACK OF UPPER SUPPORT SHOULD BRING ABOUT A DRIER DAY WITH FORECAST SOUNDINGS SHOWING EXTENSIVE DRYING ABOVE A RATHER LARGE MID LEVEL CAP THIS AFTERNOON. MODELS DO SHOW SOME WEAK LOW LEVEL CONVERGENCE DEVELOPING MAINLY FAR SW LATER ON AS THE BOUNDARY LAYER FLOW TURNS MORE SE AND SOME RETURN IN 85H THETA-E RETURNS. HOWEVER THIS LOOKS TO FOCUS MORE WITH OROGRAPHIC SUPPORT AND DIFF HEATING AND LESS OUT EAST WHERE A DRIER NE TRAJECTORY WILL OCCUR. MOST GUIDANCE BASICALLY IN LINE WITH SOME ISOLATED POP UP CONVECTION WITH SHOTGUN NATURE COVERAGE MAINLY BLUE RIDGE AND FAR NW GIVEN MODEST CAPE/INSTABILITY. THUS WILL RUN WITH MORE CHANCE POPS IN THESE SPOTS WITH A BROAD 20ISH POP COVERAGE ELSW EXCEPT THE SE AND FAR WESTERN SLOPES FOR NOW. DRIER AIR UNDER INCREASING SUN...AFTER EARLY LOW CLOUDS/FOG...ALONG WITH WARMING ALOFT WEST SHOULD BALANCE OUT HIGHS IN THE LOW/MID 80S OVERALL. WEAK SURFACE HIGH WILL BRIDGE IN FROM THE NE OVERNIGHT WHICH SHOULD KEEP WEAK SUBSIDENCE IN PLACE UNDER THE LEADING EDGE OF THE STRONGER 5H RIDGE TO THE WEST. MAY SEE ISOLATED SHRA/TSRA CONTINUE FOR A BIT DURING THE EVENING BEFORE FADING TO MORE FOG OVERNIGHT AS A PERIOD OF CLEARING TAKES SHAPE. HOWEVER FLOW...ALBEIT WEAK...TURNING AROUND TO A MORE S/SE COMPONENT IN THE 8-9H LAYER MAY TEND TO REDEVELOP SOME STRATO-CU ESPCLY SOUTHERN BLUE RIDGE WHERE TRAPPED MOISTURE FROM THE EVENING MAY LINGER. OTRW MOSTLY CLEAR TO PC. KEPT TEMPS CLOSER TO THE WARMER MET MOS AS MAV DEWPOINTS LOOK TOO DRY BY MORNING EVEN IF SKIES ARE TOTALLY CLEAR.
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&& .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... AS OF 320 AM EDT FRIDAY... WEAK HIGH PRESSURE WILL RIDGE ACROSS OUR REGION ON SATURDAY. SCATTERED DIURNAL CONVECTION IS EXPECTED TO DEVELOP OVER THE MOUNTAINS AND ADJACENT FOOTHILLS SATURDAY AFTERNOON INTO SATURDAY NIGHT WITH LIGHT UPSLOPE FLOW AND LIGHT LOW LEVEL CONVERGENCES FOCUSED ON THE MOUNTAINS. SWODY2 PLACED THE SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST WITH BETTER INSTABILITY AND LIFT. FELT THAT THE ADJMAV CAPTURED THE SATURDAY HIGH TEMPERATURES WITH READINGS FROM AROUND 80 DEGREES IN THE MOUNTAINS TO THE LOWER 90S IN THE PIEDMONT. KEPT THE LIGHT POPS GOING IN THE WEST UNTIL 06Z SUNDAY THEN DRY OUT INTO SUNDAY MORNING. LOW TEMPERATURES SATURDAY NIGHT REMAIN MILD WITH VALUES FROM THE LOWER 60S IN THE WEST TO AROUND 70 DEGREES IN THE EAST. AS THE RIDGES SLIDE EAST SUNDAY...WINDS BECOME SOUTHWEST SLOWLY INCREASING MOISTURE. THE GFS IS MORE ROBUST WITH COVERAGE OF SHOWERS AND THUNDERSTORMS SUNDAY AFTERNOON COMPARED TO THE ECMWF. STORMS WILL BE A LITTLE MORE WIDESPREAD COMPARED TO SATURDAY BUT STILL MAINTAINED CHC CATEGORY WITH NO FORCING. STILL NOT SEEING ENOUGH INSTABILITY OR ANY FORCING FOR MUCH IN THE WAY OF SEVERE THREAT. BECAUSE OF THE WESTERLY COMPONENT OF THE FLOW...QUESTIONS REMAIN ABOUT HOW FAR EAST THUNDERSTORMS MAY DEVELOP OR SHIFT TO LATER IN THE DAY. MUCH MORE ORGANIZED AND POSSIBLY SEVERE STORMS WELL UPSTREAM CLOSER TO NEXT FRONTAL BOUNDARY SHOULD REMAIN WELL TO THE WEST THROUGH THE NIGHT. HIGH TEMPERATURES ON SUNDAY WILL BE SEASONABLE FROM THE LOWER 80S IN THE WEST TO THE LOWER 90S IN THE EAST. GFS MOS IS HINTING THAT WE COULD SEE A FEW MID 90S IN THE SOUTHEAST DEPENDING ON THE CLOUD COVER AND STRENGTH OF THE DOWNSLOPE. A COLD FRONT APPROACHING FROM THE WEST ON MONDAY WILL CREATE A WARM AND HUMID AIRMASS WITH PLENTY OF INSTABILITY TO SET OFF SOME AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. RAISED POPS TO INCLUDE THE MENTION OF LIKELY IN THE NORTHWEST. HIGH TEMPERATURES ON MONDAY WILL VARY FROM THE MID 80S IN THE WEST TO THE MID 90S IN THE EAST. LOWS MONDAY WILL GENERALLY BE FROM THE LOWER 60S IN THE MOUNTAINS TO AROUND 7O DEGREES IN THE PIEDMONT. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 1230 PM EDT THURSDAY... WAVES OF UPPER LEVEL ENERGY ASSOCIATION WITH AN UPPER LEVEL TROF AND ASSOCIATED CUT OFF LOW OVER THE NORTHERN GREAT LAKES WILL BRING ADDITIONAL SHOWERS AND THUNDERSTORMS AHEAD OF THE FRONT ON TUESDAY. TIMING DIFFERENCES REMAIN ON WHEN EXACTLY THE COLD FRONT WILL CROSS OUR REGION...HOWEVER IT WILL HAPPEN EITHER LATE TUESDAY OR EARLY WEDNESDAY. BEHIND THE COLD FRONT...HIGH PRESSURE BUILDS IN AND A NOTICEABLE DROP IN HUMIDITY WILL BE FELT AS DEWPTS CRASH INTO THE 40S AND 50S. HIGH TEMPS WEDNESDAY AND THURSDAY WILL BE SEVERAL DEGREES BELOW NORMAL. THIS MEANS MID TO UPPER 70S ACROSS THE MOUNTAINS AND LOW 80S EAST OF THE BLUE RIDGE. DEPENDING ON CLOUD COVER...WOULD NOT BE SURPRISED TO SEE A FEW MOUNTAIN LOCATIONS DROP INTO THE MID TO UPPER 40S FOR NIGHT TIME LOWS ESPECIALLY ON THURSDAY. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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AS OF 159 PM EDT FRIDAY... DRIER AIR UNDER HIGH PRESSURE IS RESULTING IN SCATTERED CUMULUS MOST AREAS THIS AFTERNOON AND ONLY EXPECTED ISOLATED SHOWERS OR A THUNDERSTORM ALONG HIGHER TERRAIN AND NOT WORTH MENTIONING SPECIFICALLY IN TAFS. EXPECTING VFR CONDITIONS AND LIGHT WINDS REMAINDER OF DAY. SOME BROKEN CLOUDS POSSIBLE TONIGHT ALONG BLUE RIDGE...BUT LIKELY TO REMAIN VFR AT ATFS SITES UNTIL PATCHY FOG FORMS AGAIN IN TYPICALLY VALLEYS AND WILL LIKELY BRING IFR FOG AND LOW VIGS TO KLWB AND KBCB BEFORE DAWN...AND HAVE ALSO INCLUDED KDAN ALTHOUGH NOT AS CONFIDENT IN IFR CONDITIONS THERE. PERHAPS MVFR FOG AT KROA/KLYH/KBLF DURING EARLY MORNING HOURS AS WELL. SIMILAR DAY SATURDAY...WITH ONLY ISOLATED SHOWER/THUNDERSTORM POTENTIAL AND MOST LIKELY AFTER CURRENT VALID TAF PERIOD. LIGHT WINDS AGAIN...BUT A LITTLE SHIFT MORE TOWARD THE S/SW. EXTENDED AVIATION DISCUSSION... MOISTURE AND MORE WIDESPREAD SHRA/TSRA LIKELY TO RETURN FOR SUNDAY AND EARLY NEXT WEEK AS A BROAD UPPER TROUGH DIGS INTO THE GREAT LAKES REGION AND RESULTANT CYCLONIC FLOW PROVIDES INCREASINGLY UNSTABLE/UNSETTLED CONDITIONS ACROSS THE REGION. APPEARS BEST SHOT AT WIDESPREAD MVFR/IFR LATE MONDAY AND INTO TUESDAY WITH THE PASSAGE OF A STRONG COLD FRONT FOR MID JULY WITH OCNL MVFR IN PASSING AFTERNOON/EVENING TSRA IN ADVANCE OF THE BOUNDARY ON MONDAY. PATCHY LATE NIGHT/EARLY MORNING FOG WILL RESULT IN LOCAL MVFR TO IFR CONDITIONS DURING THE LATE NIGHTS AND EARLY MORNINGS...ESPECIALLY IN VALLEY LOCATIONS AND WHERE EARLIER AFTERNOON RAINFALL OCCURRED.
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&& .HYDROLOGY... AS OF 1000 AM EDT THURSDAY... US DROUGHT MONITOR ISSUED JULY 10 2014...SHOWS EXPANSION OF D0...ABNORMALLY DRY CATEGORY...ACROSS MUCH OF NEW RIVER VALLEY AND OVER PARTS OF THE VA AND NC PIEDMONT...CENTERED AROUND DANVILLE. PULASKI COUNTY VA APPEARS TO BE NEAR THE EPICENTER OF THE DEVELOPING CONDITIONS OVER THE NEW RIVER VALLEY WITH MUCH OF THAT COUNTY RECEIVING LESS THAN 50 PERCENT OF NORMAL RAINFALL SINCE EARLY MAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/SK NEAR TERM...JH/SK SHORT TERM...KK LONG TERM...CF/KK AVIATION...JH/RAB/SK HYDROLOGY...PC

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