Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 031927 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 327 PM EDT MON AUG 3 2015 .SYNOPSIS... HIGH PRESSURE WILL REMAIN ACROSS THE REGION THIS EVENING BEFORE WEAKENING AHEAD OF A COLD FRONT THAT WILL APPROACH FROM THE WEST LATE TONIGHT. THIS FRONT SHOULD CROSS THE AREA TUESDAY BEFORE STALLING OVER THE CAROLINAS TUESDAY NIGHT INTO WEDNESDAY. LOW PRESSURE WILL RIDE ALONG THE FRONT BRINGING A BETTER CHANCE FOR MORE WIDESPREAD SHOWERS AND STORMS THURSDAY INTO FRIDAY. && .NEAR TERM /THROUGH TUESDAY/... AS OF 300 PM EDT MONDAY... MCS ACTIVITY THAT DISSIPATED OVER WV BEFORE SUNRISE HAS LEFT A BUBBLE HIGH ACROSS THE REGION THAT HAS SUPPRESSED CONVECTIVE ACTIVITY ACROSS THE REGION AND PUSHED STORM DEVELOPMENT OFF TO OUR EAST. THIS SHOULD YIELD A DRY EVENING BEFORE ADDITIONAL ACTIVITY DEVELOPS ALONG THE COLD FRONT APPROACHING FROM THE NORTHWEST AND ARRIVES AT THE WESTERN SLOPES OF THE APPALACHIANS. THERE IS SOME DISCREPANCY IN WHEN THE PRECIPITATION ARRIVES BUT BELIEVE THE MOST LIKELY TIMING WILL BE NO EARLIER THAN 06Z AND EXPECT CONVECTION WILL BE ON THE DECLINE WHEN IT ARRIVES SO DO NOT EXPECT IT TO MAKE MUCH HEADWAY PAST SOUTHEAST WV AND THE MOUNTAIN EMPIRE REGION OF VA. THE FRONT WILL BE SLOWLY MOVING THROUGH THE AREA TOMORROW AND EXPECT THIS TO TRIGGER SHOWER/THUNDERSTORM DEVELOPMENT AGAIN TUESDAY AFTERNOON. MODELS APPEAR MORE BULLISH ON CONVECTIVE DEVELOPMENT WITH SLIGHTLY BETTER DYNAMICS BUT INSTABILITY IS LIMITED SO SEVERE THREAT WILL BE MARGINAL AT BEST AND CONFINED TO EASTERN SECTIONS AS PER THE CURRENT SPC DAY 2 OUTLOOK. WILL KEEP POPS IN THE CHANCE CATEGORY AND WAIT TO SEE HOW THE SITUATION UNFOLDS TONIGHT TO MAKE ANY NECESSARY ADJUSTMENTS. EXPECT TEMPERATURES TO BE A BIT MORE MILD TONIGHT AS CLOUDS AND DEW POINTS START TO INCREASE. EXPECT LOWS TONIGHT RANGING FROM UPPER 60S/AROUND 70 EAST TO LOW/MID 60S WEST. HIGHS TOMORROW WILL BE AIDED BY WARM AIR ADVECTION AND INCREASING DOWNSLOPE WINDS...SO HIGHS TUESDAY WILL BE IN THE LOW/MID 90S EAST TO MID/UPPER 80S WEST. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... AS OF 215 PM EDT MONDAY... COLD FRONT WILL HAVE JUMPED INTO THE PIEDMONT LEE TROUGH BY EARLY TUESDAY EVENING BEFORE PUSHING EAST ALLOWING HIGH PRESSURE TO BUILD IN FROM THE NW THROUGH WEDNESDAY. WITH STRONG DOWNSLOPING IN PLACE...POPS APPEAR QUITE IFFY TUESDAY EVENING EXCEPT PERHAPS OVER THE FAR WEST WHERE CLOSER TO A DEEPER MOISTURE AXIS TO THE WEST...AND ALONG THE EASTERN PERIMETER GIVEN WEAKER DOWNSLOPE ESPCLY WHEN MIXING WEAKENS. HOWEVER INSTABILITY NOT OVERLY IMPRESSIVE SO RUNNING WITH ONLY ISOLATED EVENING POPS IN THESE SPOTS BEFORE DRY ADVECTION WINS OUT OVERNIGHT. AREA WILL REMAIN IN BETWEEN FEATURES AND UNDER A BUBBLE HIGH WEDNESDAY AIDED BY WEST/NW FLOW THROUGH THE COLUMN AND LOWER PWATS. MOST GUIDANCE INCLUDING THE LATEST ENSEMBLES HAVE LITTLE PRECIP UNDER THE SUBSIDENCE WEDNESDAY SO TRIMMED BACK TO ONLY ISOLATED POPS ACROSS THE SW AND FAR EASTERN COUNTIES LATE IN THE DAY. HIGH TEMPS WEDNESDAY DON`T APPEAR QUITE AS HOT AS EARLIER GIVEN DECENT 85H COOLING DESPITE DOWNSLOPE ALOFT AND MORE SUN. STILL THINK SOME LOW/MID 90S LIKELY EAST AND 80S WEST. MOISTURE WILL BEGIN TO INCREASE WEDNESDAY NIGHT AS AN INITIAL WAVE HEADS EAST OUT OF THE SOUTHERN PLAINS AND BEGINS TO LIFT THE FRONT BACK NORTH WITH WEAK OVERRUNNING IN PLACE. GUIDANCE REMAINS SLOW TO MOISTEN THINGS UP WEDNESDAY NIGHT WITH THE BEST FLUX OF DEEP MOISTURE NOT RETURNING UNTIL THURSDAY PER THE LATEST GFS/EURO. SINCE APPEARS BEST MOISTURE/LIFT WILL BE MAINLY OVER THE FAR WEST/NORTH WITH THE FRONT...WILL KEEP LOW CHANCE POPS MOUNTAINS WEDNESDAY NIGHT AND SLIGHTS OUT EAST. PLUME OF DEEPER MOISTURE ADVECTS IN WITH THE LEAD SHORTWAVE THURSDAY INTO THURSDAY NIGHT WITH MODELS SHOWING DECENT INSTABILITY THURSDAY AFTERNOON AS WELL AS LIFT WITH THE SURFACE WAVE THURSDAY NIGHT. HOWEVER STILL SOME UNCERTAINTY IN EXACTLY WHERE THE CORE OF THIS SYSTEM WILL TRACK WITH SOME SOLUTIONS FARTHER WEST WHICH WOULD LIMIT FOCUS UNTIL THURSDAY NIGHT AFTER LOSS OF HEATING. THEREFORE KEEPING LIKELY POPS CONFINED TO THE WEST AND CHANCE OUT EAST FOR NOW. LEFT TEMPS CLOSER TO A MORE BLENDED SOLUTION PENDING DEGREE OF SHOWER COVERAGE WHICH COULD MAKE THINGS COOLER THAN THE 80S TO AROUND 90 SE ON THURSDAY. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 100 PM EDT MONDAY... STRONG SHORTWAVE FOR EARLY AUGUST WILL PASS ACROSS OR JUST NORTH OF THE REGION TO START THE PERIOD ALLOWING A TRAILING COLD FRONT TO SLIDE SOUTHEAST INTO THE CAROLINAS BY LATER FRIDAY INTO FRIDAY NIGHT. THIS ASSOCIATED WITH ANOTHER DIGGING 5H TROUGH THAT WILL BRING THE ONSET OF THE NEXT ROUND OF SLIGHTLY COOLER TEMPERATURES FOR NEXT WEEKEND. HOWEVER NEW GUIDANCE CONTINUES TO FLIP FLOP AS SOME SOLUTIONS NOW NOT AS DEEP OR PROLONGED WITH THE EASTERN UPPER TROUGH IN HAVING A PASSING 5H COOL POOL EARLY IN THE WEEKEND BEFORE RETURNING TO MORE ZONAL FLOW AND SOME RETURN IN MOISTURE BY DAY7. THIS AHEAD OF ADDED UPSTREAM CLIPPER TYPE ENERGY THAT SHOULD GIVE THE INITIAL SYSTEM A BIT OF A BOOT TO START. THIS COULD ALSO KEEP MORE CLOUDS AROUND AT TIMES DESPITE WEAK SURFACE RIDGING IN PLACE...ALONG WITH POSSIBLE ISOLATED SHOWERS SW SUNDAY AND MAINLY OVER THE WEST MONDAY AHEAD OF THE NEXT WAVE. THUS AFTER HIGHER CHANCE TO LOW LIKELY POPS ESPCLY NORTH/WEST WITH THE FRONTAL PASSAGE FRIDAY...WILL HANG ONTO SOME ISOLATED TO LOW CHANCE POPS SATURDAY AND OVER THE FAR SW SUNDAY DESPITE THE SURFACE FRONT WELL TO THE SOUTH. OTRW THINKING THAT MUCH OF THE WEEKEND INTO MONDAY WILL REMAIN DRY PENDING LATER TRENDS WITH THE TIMING OF THE FRONTAL PROGRESSION FROM LATE IN THE WEEK. TEMPS TO COOL BACK TO JUST BELOW SEASONAL LEVELS BUT NOT QUITE AS COOL AS SEEN YESTERDAY FOR NOW. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... AS OF 115 PM EDT MONDAY... THERE ARE A LOT OF SUBTLE FEATURES TO CONSIDER THAT MAKE FOR SOME UNCERTAINTY WITH THIS TAF PACKAGE. THE REGION IS CURRENTLY BETWEEN SYSTEMS AS A COLD FRONT APPROACHES FROM THE NORTHWEST WITH A TROF/BOUNDARY TO OUR EAST. RADAR SHOES THAT STORMS HAVE FIRED ALONG THE TROF/BOUNDARY EAST OF THE AREA AND BELIEVE ANY REDEVELOPMENT FURTHER WEST WILL BE ISOLATED AND NOT WORTH A VCTS MENTION...AND MESO MODELS INDICATE ANY ACTIVITY APPROACHING FROM THE NORTHWEST WILL NOT ARRIVE UNTIL AFTER 00Z. THIS WILL YIELD VFR TAFS THROUGH THE EARLY PART OF THE PERIOD. THERE IS SOME DISCREPANCY IN THE MESO MODELS AS TO WHEN ACTIVITY WILL ARRIVE FROM THE NORTHWEST. BELIEVE THE MOST LIKELY TIMING IS FOR ACTIVITY TO ARRIVE NO EARLIER THAN 06Z AND BE DIMINISHING AS IT APPROACHES. WILL INTRODUCE AN MVFR CIG AT KBLF/KLWB BUT KEEP VFR CLOUDS ELSEWHERE. THE ANTICIPATED CLOUDS/PRECIPITATION WILL COMPLICATE THE FOG FORECAST TONIGHT. TO THE EAST CONDITIONS SHOULD FAVOR RADIATIONAL COOLING AND SOME THIN FOG DEVELOPMENT. FOG AND STRATUS WAS NOT TOO FAR OFF TO THE SOUTHEAST THIS MORNING AND INDICATIONS ARE THAT KDAN WILL GET INTO SOME MVFR FOG AND SOME SCATTERED LOW CLOUDS TOWARD DAYBREAK. CLOUD COVER WILL INHIBIT RADIATIONAL COOLING WEST OF THE RIDGE BUT THE EXACT AMOUNT OF CLOUDS AND PRECIPITATION WILL PLAY A BIG ROLE IN FOG POTENTIAL. CURRENTLY FEEL CONDITIONS WILL NOT FAVOR FOG AND WILL OMIT FROM TAFS THIS PACKAGE. IF UPSTREAM CLOUDS/PRECIPITATION ARE LESS THAN ANTICIPATED EARLY TONIGHT THIS WILL TIP THE SCALES IN FAVOR OF FOG AND IT MAY BECOME NECESSARY TO ADD MVFR CONDITIONS AT KBLF/KBCB WITH SOME IFR/LIFR AT KLWB. THE FRONTAL BOUNDARY WILL BE MOVING THROUGH THE REGION TOMORROW AND EXPECT SOME SHOWER/THUNDERSTORM ACTIVITY TO DEVELOP LATE IN THE TAF PERIOD...BUT DUE TO UNCERTAINTY IN TIMING AND LOCATION WILL NOT INCLUDE ANY MENTION OF TS/SHRA WITH THIS PACKAGE. EXPECT WINDS TO BE WESTERLY WITH SOME LOW LEVEL GUSTS POSSIBLE... ESPECIALLY TOMORROW AS WINDS BECOME MORE NWLY WITH THE FRONTAL PASSAGE. EXTENDED AVIATION FORECAST... MOSTLY VFR OUTSIDE OF ANY DEEP CONVECTION THROUGH THE PERIOD. A FRONT WILL STALL ACROSS THE MID ATLANTIC FOR MID WEEK WHICH COULD BRING A BIT MORE COVERAGE OF SHOWERS/THUNDERSTORMS LATER WEDNESDAY AND A BETTER CHANCE THURSDAY. THE THREAT OF SUB-VFR REMAINS LOW UNTIL THURSDAY...EXCEPT FOR THE TYPICAL FOG POTENTIAL AT KLWB/KBCB EACH MORNING BETWEEN 09-13Z. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH NEAR TERM...MBS SHORT TERM...JH LONG TERM...JH AVIATION...MBS/PM

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