Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 020811 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 411 AM EDT THU OCT 2 2014 .SYNOPSIS... HIGH PRESSURE WILL AGAIN WEDGE SOUTH ALONG THE EASTERN SLOPES OF THE APPALACHIANS THROUGH TONIGHT. A STRONG COLD FRONT ARRIVES LATER FRIDAY FOLLOWED BY MUCH COOLER AIR FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 330 AM EDT THURSDAY... LOW DECK AND FOG IN THE EAST THIS MORNING MAY SHIFT TO ROANOKE BEFORE RETREATING AGAIN AND ERODING ACROSS THE PIEDMONT TO SCATTERED CU/SC BY MIDDAY. MODELS FAVOR DRIER SOLUTION WITH UPPER RIDGING MOVING IN THIS AFTERNOON...WITH ANY SHOWER ACTIVITY WITH LAST VORT STAYING EAST OF OUR AREA THIS MORNING. WEAK WEDGE TO ERODE AS WELL BY LATE IN THE DAY AS FLOW TURNS MORE SOUTHEAST AHEAD OF THE STORM SYSTEM MOVING INTO THE MISSISSIPPI VALLEY. THE MODELS ARE TRACKING THIS FRONT INTO OHIO/WRN KY AND WRN TN BY LATE TONIGHT WITH SHOWERS ARRIVING IN ISOLATED FASHION TOWARD THE SW VA MTNS BY DAWN. OVERALL LOOKING AT SKIES BEING SUNNY/MOSTLY SUNNY WEST TODAY...BECOMING MOSTLY SUNNY IN THE AFTERNOON EAST...WITH HIGHS RANGING FROM THE MID TO UPPER 70S MOUNTAINS...TO LOWER 80S SOUTHEAST. TONIGHT...GOING TO SEE ADVANCEMENT OF LOWER CLOUDS AGAIN TOWARD THE PIEDMONT AS SE-E FLOW CONTINUES. FORECAST SOUNDING SUGGEST PATCHY DRIZZLE IN THE FOOTHILLS OF VA NORTH OF BEDFORD/LYNCHBURG LATE. CLOUD COVER WILL INCREASE LATE IN THE WEST. LOWS WILL BE MILDER THAN PAST COUPLE OF DAYS WITH MOST LOCATIONS IN THE MID TO UPPER 50S. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 310 AM EDT THURSDAY... SHORTWAVE RIDGING SLOWLY BREAKS DOWN FRIDAY IN ADVANCE OF THE UPSTREAM 5H TROUGH AND ITS ASSOCIATED COLD FRONT THAT LOOKS TO PUSH THROUGH THE REGION FROM THE WEST FRIDAY NIGHT. MODELS HAVE SETTLED A BIT MORE ON THE SLOWER TIMING OF THE BOUNDARY WITH SORT OF AN INITIAL PUSH OF SHOWERS ACROSS THE WEST AHEAD OF THE LEADING WIND SHIFT BOUNDARY FRIDAY AFTERNOON...WITH THIS AXIS OF PRECIP POSSIBLY HEADING EAST OF THE BLUE RIDGE LATE FRIDAY INTO FRIDAY NIGHT. HOWEVER THE LATEST 00Z ECMWF BASICALLY SPLITS MUCH OF THE PRECIP ENTERING THE WEST FRIDAY AS BEST UPPER SUPPORT/LIFT LAGS THE SURFACE BOUNDARY AS A SECONDARY SPEED MAX ROTATES AROUND THE DEEP UPPER COLD POOL. OTHER SOLUTIONS SURGE THE INITIAL BAND OF PRECIP INTO THE AREA A BIT FASTER BUT MOSTLY INTO WEAK INSTABILITY/LAPSES OVER THE WEST AND THE LINGERING WEDGE OUT EAST. FOR NOW PLAN TO KEEP TIMING SIMILAR WITH HIGHEST CAT/LIKELY POPS WEST OF THE BLUE RIDGE THROUGH EARLY AFTERNOON...THEN OUT EAST LATE DAY INTO THE EVENING. SEVERE THREAT AGAIN LOOKS MARGINAL PER FORECAST CAPES OF BELOW 1K J/KG AND A RATHER SATURATED ENVIRONMENT THAT LIKELY WILL KEEP STRONG UNIDIRECTIONAL WINDS ALOFT UNLESS SOME SORT OF LOW TOPPED CONVECTIVE BAND SURGES OUT FRIDAY AFTERNOON. MAY ALSO HAVE THE SCENARIO OF SEEING MORE CONCENTRATED LOW TOPPED SHRA/TSRA TO THE NORTH CLOSER TO THE DYNAMICS ALOFT...AND MORE SURFACE BASED CONVECTION SOUTH PER HIGHER INSTABILITY. THIS WOULD LEAVE WEAKER SHOWERS IN BETWEEN ACROSS OUR REGION MAINLY FRIDAY EVENING SO SOMETHING TO WATCH. OTRW HIGH TEMPS REMAIN A BIT TRICKY AS GUSTY SOUTHERLY WINDS DEVELOP ALOFT WHILE WILL HAVE CLOUDS INCREASING AND THE BEST WARM ADVECTION TO THE SOUTH. THINK WITH SLOWER PRECIP ARRIVAL THAT THE EAST SHOULD RISE CLOSER TO THE WARMER MAV MOS WITH COOLER 70S SIMILAR TO THE MET VALUES IN THE WEST. SHOWERS/ISOLATED TSRA SHOULD PUSH EAST AND OUT OF THE AREA AFTER MIDNIGHT FRIDAY NIGHT WITH A SURGE OF COLD ADVECTION SPILLING ACROSS THE MOUNTAINS LATE. THIS WILL TURN ON A BRIEF PERIOD OF UPSLOPE -SHRA BUT LIMITED BY MORE OF A WESTERLY TRAJECTORY AND EXODUS OF MOISTURE WITH THE FRONT TO THE EAST...SO MAINLY CHANCE POPS THERE. OTRW HIGH POPS EAST EARLY...AND CHANCE ELSW TAPERING TO MOSTLY THE FAR NW LATE AS DOWNSLOPE DRYING KICKS IN. PART OF THE UPPER COLD POOL ROTATES ACROSS SATURDAY AS STRONG SURFACE HIGH PRESSURE BUILDS IN FROM THE SW ON GUSTY NW BREEZES. GRADUAL DRYING AND INCREASING SUBSIDENCE SHOULD CURTAIL MOST UPSLOPE SHOWERS BY AFTERNOON BUT LIKELY STILL SOME CLOUDS UNDER THE TROUGH OUT WEST FOR MUCH OF THE DAY. WILL FEEL LIKE OCTOBER WITH 85H TEMPS NEAR 0C NW AND COOL ADVECTION FOR MOST OF THE DAY KEEPING HIGHS ONLY IN THE LOW/MID 50S MOUNTAINS. A BIT WARMER EAST WHERE SHOULD BUMP INTO THE MID/UPPER 60S GIVEN DOWNSLOPE AND MORE INSOLATION SOONER. COLDEST NIGHT OF THE SEASON SO FAR IN STORE SATURDAY NIGHT WITH HIGH PRESSURE NOSING IN FROM THE SW AND MOUNTAIN CLOUDS FADING. MOST MOS TEMPS SUPPORT A RATHER WIDESPREAD SWATH OF LOW/MID 30S WESTERN MOUNTAINS WITH UPPER 30S/LOW 40S EAST. HOWEVER STILL UNCERTAINTY WITH THE DEGREE OF DECOUPLING WITH THE PARENT HIGH SO FAR SOUTH AND A WESTERLY COMPONENT IN PLACE. A BIT MORE CLOUDS NW COULD ALSO LIMIT TEMP FALLS AS APPEARS LOCATIONS ACROSS THE SW MAY BE COLDER PER BETTER RADIATIONAL COOLING UNDER THE RIDGE WHILE THE NORTH AND NW STAY SLIGHTLY WARMER UNDER A LIGHT BREEZE. THIS MAY BRING SOME FROST ESPCLY FROM THE NEW RIVER VALLEY AND POINTS SW INTO THE N CAROLINA MOUNTAINS WITH EVEN BRIEF FREEZE CONDITIONS POSSIBLE IN THE VALLEYS IF WINDS CAN DIMINISH SOONER. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 310 PM EDT WEDNESDAY... FOLLOWING THE PASSING OF A COLD FRONT FRIDAY NIGHT...THE REGION WILL REMAIN UNDER AN UPPER LEVEL TROUGH THROUGH EARLY NEXT WEEK. COOLER THAN NORMAL AFTERNOON TEMPERATURES LIKELY THROUGH MONDAY...THEN MODERATING TOWARDS NORMAL BY MID WEEK. OVERNIGHT LOWS SATURDAY AND POSSIBLY SUNDAY NIGHT WILL BE COLD WITH MOUNTAINS TEMPERATURES DROPPING INTO THE 30S...40S IN THE EAST. FROST IS POSSIBLE ACROSS THE WEST IF WINDS COULD DECOUPLE EARLY SUNDAY MORNING. GROUND TEMPERATURES WILL REMAIN WARM ENOUGH TO LIMIT ANY FROST TO ISOLATED AREAS. THE EASTERN HALF OF THE USA WILL REMAIN UNDER A BROAD BUT FLAT TROUGH THROUGH TUESDAY. THERE COULD BE A MID LEVEL DISTURBANCE MOVING ACROSS THE OHIO VALLEY MONDAY...BUT WITH LIMITED MOISTURE...JUST SEEING AN INCREASE IN CLOUD COVER FOR THE AREA. TUESDAY MAYBE THE NEXT CHANCE FOR RAIN...AS A FRONT IS SCHEDULED TO MOVE OVER THE REGION. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... AS OF 130 AM EDT THURSDAY... ANOTHER VARIABLE NIGHT OUT EAST FOR TAFS...WITH MVFR CIGS AT LYH TO IFR/LIFR VSBYS AT DAN. MODELS FAVOR VSBYS DROPPING DESPITE THE LOWER CLOUDS AT LYH...AND HAVE THIS IN BY 09Z. TO THE WEST...THINK MVFR CIGS COULD SHIFT INTO ROANOKE BY 09Z AS WELL BUT WILL BE A SCT V BKN SITUATION BUT LEANED TOWARD BKN..WITH MVFR FOG. BLF WILL STAY VFR WHILE LWB/BCB SEE CLEAR SKIES BUT FOG REDUCING VSBYS DOWN TO 1/4SM. FOG BURNS OFF IN THE WEST BY 14Z...WHILE THE SUB VFR CIGS IN THE EAST HANG TOUGH THROUGH ABOUT MIDDAY BEFORE SCATTERING OUT. WIND FIELDS REMAIN LIGHT THROUGH THE PERIOD. EXTENDED AVIATION DISCUSSION... FRONTAL BOUNDARY AND ASSOCIATED SHOWERS TO IMPACT THE MOUNTAINS BY LATE FRIDAY MORNING AND THE PIEDMONT IN THE AFTERNOON. SUB VFR EXPECTED IN HEAVIER SHOWERS OR ISOLATED TSRA. SHOWERS EXITING THE MTNS BY LATE FRIDAY EVENING AND THE PIEDMONT TOWARD DAWN SATURDAY. TIMING OF CLEARING IS STILL TRICKY. SATURDAY SHOULD BE CLEARING OUT IN THE PIEDMONT TO ROANOKE/BLACKSBURG BUT UPSLOPE MVFR CIGS AT BLF/LWB MAY OCCUR INTO SAT AFTERNOON...WITH BREEZY NW WINDS. WINDS DIMINISH SATURDAY NIGHT THEN VFR SUNDAY INTO MONDAY. A FRONT CLOSES IN MONDAY AFTERNOON WITH SOUTHWEST WINDS INCREASING. LOOKS LIKE SHOWERS MAY IMPACT THE MOUNTAINS BY MONDAY EVENING...WITH POSSIBLE SUB VFR. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...RCS/WP NEAR TERM...WP SHORT TERM...JH LONG TERM...RCS AVIATION...AMS/CF/WP

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