Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 170511 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 111 AM EDT WED SEP 17 2014 .SYNOPSIS... A COOL WEDGE OF HIGH PRESSURE SETTLES IN FROM THE NORTH EARLY WEDNESDAY. THE HIGH WILL STRENGTHEN TO THE NORTH OF THE REGION THROUGH THE REST OF THE WEEK...KEEPING RATHER COOL BUT OVERALL DRY WEATHER IN PLACE. && .NEAR TERM /THROUGH TODAY/... AS OF 930 PM EDT TUESDAY... BUMPED UP CLOUD COVER ACROSS THE MOUNTAINS AS SURFACE OBS AND IR SATELLITE CONTINUE TO SHOW LOW LEVEL CLOUDS ACROSS BLF AND SE WV. ALSO ADJUSTED POPS DOWN SLIGHTLY FOR THE NEXT FEW HOURS AS THINKING IS LIGHT RAIN/DRIZZLE WONT OCCUR UNTIL CLOSER TO SUNRISE IN THE MORNING. AS OF 715 PM EDT TUESDAY... SHOWERS AND STORMS HAVE FADED/SHIFTED SOUTH OF THE CWA EARLY THIS EVENING AND LOWERED POPS TO ACCOUNT FOR THIS. HAD ONE REPORT OF NICKEL TO QUARTER SIZED HAIL FROM A STORM THAT MOVED OVER BELEWS LAKE IN ROCKINGHAM COUNTY NC AT 445 PM. DRIER AIR SHIFTING SLOWLY SWD...BUT STILL LOOKING AT LOW LVL MOISTURE STAYING PUT LATER TONIGHT...SO KEPT IN CLOUDS MORE EAST OF THE MTNS THOUGH THERE IS A BATCH OF LOW CLOUDS ACROSS SE KY/WRN WV ATTM...WHICH MAY INCREASE INTO SE WV...SO MAY HAVE TO UP SKY COVER HERE. OVERNIGHT...MODELS KEEP JUST ENOUGH MOISTURE IN THE LOW LVLS FOR PATCHY DRIZZLE OVER THE BLUE RIDGE AND ADJACENT AREAS...WITH THE NAM MOST AGGRESSIVE WITH THIS SCENARIO. PREVIOUS VALID DISCUSSION... HIGH PRESSURE WILL PUSH RAPIDLY EAST ACROSS THE SOUTHERN GREAT LAKES. AS THE HIGH REACHES NEW ENGLAND... IT WILL THEN BUILD SOUTHWARD ACROSS THE MID ATLANTIC TO WEDGE AGAINST THE EASTERN FACE OF THE APPALACHIANS. AS SUCH...EXPECT WINDS TO GRADUALLY SHIFT FROM NORTHWESTERLY THIS EVENING TO NORTHEASTERLY DURING THE PREDAWN HOURS OF WEDNESDAY. THE NORTHEASTERLY WIND FLOW WILL DRAW COOL MOIST AIR FROM THE ATLANTIC UP THE BLUE RIDGE MOUNTAINS...WHERE IT WILL DEVELOP INTO A MIXTURE OF FOG...DRIZZLE AND LOW CLOUDS IN THE HIGHER TERRAIN BEFORE SUNRISE. WITH WINDS HOLDING OUT OF THE EAST THROUGH THE REMAINDER OF THE DAY...WE CAN EXPECT PATCHES OF FOG AND DRIZZLE TO LINGER ACROSS THE MOUNTAINS WELL INTO THE AFTERNOON BEFORE WE SEE GRADUAL IMPROVEMENT. COOL MARINE AIR COMING AROUND THE HIGH PRESSURE WEDGE...COMBINED WITH THE CLOUD COVER...WILL KEEP AFTERNOON TEMPERATURES VERY MUCH ON THE COOL SIDE. WENT A LITTLE ON THE AGGRESSIVE SIDE IN UNDERCUTTING MODEL GUIDANCE BASED ON THE PROLONGED POTENTIAL FOR DRIZZLE AND LIGHT RAIN LASTING INTO THE AFTERNOON. WILL BE LOOKING FOR HIGHS RANGING FROM THE LOW/MID 60S ACROSS THE MOUNTAINS...TO THE UPPER 60S/LOW 70S ACROSS THE PIEDMONT. && .SHORT TERM /TONIGHT THROUGH FRIDAY/... AS OF 300 PM EDT TUESDAY... WINDS BECOMING NORTHWEST THROUGH THURSDAY NIGHT WITH ONE SHORTWAVE CROSSING THE FORECAST AREA OUT OF THE TENNESSEE VALLEY ON WEDNESDAY NIGHT FOLLOWED QUICKLY BY A WAVE IN THE NORTHERN STREAM. MODELS ALSO DEPICTING A DECENT JET STREAK AND COOLER 500 MB TEMPERATURES WITH THE TENNESSEE VALLEY SHORT WAVE WEDNESDAY NIGHT. NOT VERY IMPRESSIVE HOWEVER WITH THE LIFT OR DEPTH OF THE MOISTURE ON BUFKIT. HIGH PRESSURE AT THE SURFACE WILL BUILD IN THURSDAY NIGHT AND FRIDAY. BUFKIT SHOWED ENOUGH OF A SHALLOW LAYER OF MOISTURE AND SOUTHEAST UPSLOPE WINDS BY FRIDAY MORNING ALONG THE SOUTHERN BLUE RIDGE THAT STRATUS IS EXPECTED. OCCURRENCE OF DRIZZLE AND FOG IS ALSO POSSIBLE LATE THURSDAY NIGHT IN TO FRIDAY MORNING. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AS OF 300 PM EDT TUESDAY... AFTER A BRIEF RETURN OF SOME FLAT UPPER RIDGING ON FRIDAY NIGHT...AN AMPLIFIED EASTERN UNITED STATES TROF DIGS SATURDAY NIGHT THROUGH TUESDAY...WITH THE ECMWF EVEN HAVING A CUT OFF LOW OVER VIRGINIA BY LATE TUESDAY. LARGE SURFACE HIGH COVERS THE EAST THOUGH SATURDAY NIGHT. BACK IN SOUTHWEST FLOW AND WEAK WARM AIR ADVECTION SATURDAY NIGHT THROUGH SUNDAY...THEN MODELS STILL BRING NEXT FRONT THROUGH MONDAY. THE SOUTHWEST WINDS ON SATURDAY AND SUNDAY MAY ALSO LIMIT THE AMOUNT OF LOW LEVEL MOISTURE IN THE REGION. WILL BE WATCHING FOR DEVELOPMENT OF LOW PRESSURE ALONG THE SOUTHEAST COAST SATURDAY AND SUNDAY WHICH MAY PUSH DEEPER MOISTURE BACK INTO THE EASTERN COUNTY WARNING AREA. FOR NOW MODELS HOLD THE HIGHER MOISTURE EAST OF THE FORECAST AREA. CONTINUE TO SEE THE POTENTIAL FOR TEMPERATURES TUESDAY MORNING TO BE BELOW NORMAL. ALSO BEHIND THE COLD FRONT AS UPSLOPE CLOUD COVER WILL DEVELOP OVER THE MOUNTAINS TUESDAY AND TUESDAY NIGHT. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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AS OF 1255 AM EDT WEDNESDAY... MAINLY VFR CIGS IN THE WAKE OF THE PASSING WAVE/FRONT TO THE SE WILL SLOWLY LOWER OVERNIGHT PER INCREASING NE FLOW UNDER THE DEVELOPING WEDGE. THIS SHOULD BRING CIGS DOWN TO MVFR ACROSS THE EAST IN THE NEXT FEW HOURS WITH PERIODIC MVFR OVER THE WEST WHERE MOISTURE REMAINS TRAPPED. LOW CONFIDENCE IN HOW FAST STRATUS/FOG AND/OR DRIZZLE DEVELOP OVERNIGHT BUT APPEARS THAT LOCATIONS ALONG THE BLUE RIDGE INCLUDING KBCB/KROA WILL SEE CIGS AND PERHAPS VSBYS DROP RIGHT BEFORE DAYBREAK...WITH SIMILAR TRENDS ALSO POSSIBLE AT KLYH/KDAN. HOWEVER THINK CURRENT HIGHER CLOUD BASES WILL DELAY THE OVERALL FOG FORMATION WITH THIS OCCURRING AS CIGS LOWER BY DAWN. THUS CONTINUED LEANING TOWARD MORE IFR/MVFR LATE TONIGHT WITH SOME FOG...THOUGH THINK FOG WILL BE LESS THAN THE LOWER CIGS. SOME DEGREE OF LOW LEVEL MOISTURE WILL REMAIN STUCK ACROSS THE REGION WEDNESDAY MORNING AND JUST HOW FAST THIS ERODES TRICKY PENDING JUST HOW DEEP THE LOW CLOUDS GET OVERNIGHT. LATEST GUIDANCE REMAINS SPREAD FROM ERODING MUCH OF THE LOW CIGS PER THE GFS TO AT LEAST MVFR HOLDING FOR MUCH OF THE DAY ESPCLY BLUE RIDGE AND POINTS EAST LIKE THE NAM/CMC. FOR NOW GIVEN THE POTENTIAL FOR CIGS TO HANG LONGER WITHIN THE WEDGE...TRENDED TOWARD HOLDING MVFR IN LONGER ESPCLY KROA AND POINTS EAST WITH RETURN TO VFR SE WEST VA SITES BY AFTERNOON AND AT KBCB AROUND 18Z/2PM. ANY IMPROVEMENT IN THE EAST LIKELY TO BE SHORT AS THE WEDGE FLOPS BACK AFTER DARK WITH POSSIBLE MVFR CIGS OR LOWER REDEVELOPING DURING WEDNESDAY EVENING. EXTENDED AVIATION DISCUSSION... BROAD UPPER TROUGH REMAINS IN PLACE ACROSS THE EASTERN STATES FOR THE REMAINDER OF THE WEEK ALLOWING A LARGE AREA OF HIGH PRESSURE TO REMAIN WEDGED ACROSS THE MID ATLANTIC THROUGH THE WEEKEND. THIS SHOULD PUSH THE PESKY DEEP MOISTURE FURTHER SOUTH AWAY FROM THE REGION. HOWEVER BIGGER CONCERN WILL BE WITH TRAPPED RESIDUAL LOW LEVEL MOISTURE THAT MAY KEEP SOUTHERN/WESTERN LOCATIONS STUCK IN PERIODS OF MVFR CIGS INTO FRIDAY AS THE LOW LEVEL EAST/SE FLOW TAKES SHAPE. HIGH PRESSURE MAY BE STRONG ENOUGH TO PUSH THE LOW LEVEL MOISTURE TO THE SOUTHWEST SATURDAY AND WITH HEATING/MIXING COULD SEE THINGS RETURN TO OVERALL VFR FOR EARLY IN THE WEEKEND...BUT NOT UNTIL SATURDAY AFTERNOON AT THIS POINT. FLOW TURNS MORE SW BY SUNDAY AHEAD OF THE NEXT FRONT ALLOWING FOR WIDESPREAD VFR WITH ANY WESTERN SHOWERS LIKELY NOT ARRIVING UNTIL OVERNIGHT.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...NF/WP NEAR TERM...CF/NF/WP SHORT TERM...AMS LONG TERM...AMS AVIATION...JH/NF/WP

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