Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 270818 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 418 AM EDT WED AUG 27 2014 .SYNOPSIS... HIGH PRESSURE WILL BE OVER THE MID ATLANTIC STATES TODAY. A WEAK COLD FRONT WILL MOVE SOUTH INTO THE REGION TONIGHT AND WILL STALL ACROSS OUR AREA THROUGH THURSDAY AND FRIDAY...PROVIDING THE FOCUS FOR OCCASIONAL SHOWERS AND THUNDERSTORMS. THE FRONT WILL LIFT NORTH AGAIN ON SATURDAY AS A WARM FRONT. && .NEAR TERM /THROUGH TONIGHT/... AS OF 330 AM EDT WEDNESDAY... SURFACE HIGH PRESSURE WILL BE OVER THE AREA TODAY. A COLD FRONT THAT EXTENDED FROM NEW YORK TO MISSOURI EARLY THIS MORNING WILL MOVE SOUTH TODAY AND WILL REACH THE FORECAST AREA OVERNIGHT. A DRY AIR MASS IS IS PLACE OVER THE REGION THIS MORNING BUT AS THE FRONT APPROACHES MOISTURE WILL INCREASE. THE STRONGEST FORCING AND DYNAMICS WILL STAY TO THE NORTH OF THE COUNTY WARNING AREA. WILL HAVE A LOW PROBABILITY OF PRECIPITATION IN THE FAR NORTHERN COUNTY WARNING AREA...MAINLY BETWEEN 22Z/6PM AND 02Z/10PM. SINCE GUIDANCE HAD BEEN TOO WARM FOR THE PAST COUPLE OF DAYS WITH MAXIMUM TEMPERATURES...WILL STAY CLOSER TO BIAS CORRECTED MAV GUIDANCE FOR MAXIMUM TEMPERATURES. WITH DEW POINTS INCREASING AND SOME CLOUD COVER IN THE EVENING...LOW TEMPERATURES WILL BE NEAR THE MAV GUIDANCE...SLIGHTLY MILDER THAN THIS MORNING. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 245 AM EDT WEDNESDAY... CHRISTOBAL WILL EXIT THE PICTURE TRACKING AWAY FROM THE US THURSDAY. A WEAK COOL FRONT WILL THEN HAVE A CHANCE TO MOVE SOUTH OF THE FORECAST AREA THURSDAY AFTERNOON/NIGHT. THIS BOUNDARY MAY DEVELOP A SURFACE REFLECTION OVER NORTH CAROLINA WHICH COULD GENERATE ISOLATED SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON. WITH LIMITED MOISTURE AND A CAP OVERHEAD...ANY SHOWERS THAN FORM WILL HAVE A SHORT LIFE SPAN AND FADE WITH SUNSET. THURSDAY NIGHT...SURFACE HIGH PRESSURE WILL BE CENTERED OVER NEW ENGLAND AND WEDGE AS FAR SOUTH AS NORTH CAROLINA. THIS SURFACE RIDGE WILL DRIFT OFF THE NEW ENGLAND AND MID ATLANTIC COAST ON FRIDAY. MEANWHILE FRIDAY...AN UPPER LEVEL RIDGE WILL BE CENTERED OVER THE SOUTHEASTERN US STRETCHING NORTH INTO THE OHIO VALLEY AND MID ATLANTIC REGION. THE FORECAST AREA WILL BE ON THE NORTHERN PERIPHERY OF THIS RIDGE. WE WILL THEN NEED TO KEEP AN EYE OVER THE TENNESSEE VALLEY TO SEE IF ANY SHORT WAVES WILL TRACK OVER THE REGION. FOR NOW...MODELS ARE NOT SHOWING ANY SIGNIFICANT SHORT WAVES. AS HIGH PRESSURE DRIFTS OFF SHORE...RETREATING BOUNDARY AND SOUTHEASTERLY UPSLOPE COMPONENT WILL LIKELY TRIGGER AFTERNOON AND EVENING CONVECTION FRIDAY AFTERNOON. THE CAP IS EXPECTED TO WEAKEN OVER THE MOUNTAINS TO INCREASE THE CHANCES FOR CONVECTION TO DEVELOP. THIS CONVECTION WILL THEN DRIFT EAST TO THE FOOTHILLS AND PIEDMONT LATE IN THE AFTERNOON AND INTO THE EVENING. IN THIS PULSE STORM ENVIRONMENT...A FEW STORMS COULD BECOME STRONG TO SEVERE WITH DAMAGING WINDS THE PRIMARY THREAT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 210 PM EDT TUESDAY... AIRMASS CHANGE IN STORE AS 5H RIDGE BUILDS ACROSS THE SOUTHEAST THEN SHIFTS EWD THROUGH NEXT WEEK. THIS IS GOING TO PROVIDE HOTTER TEMPS FOR LABOR DAY WEEKEND WITH INCREASED HUMIDITY. TROUGH WILL BE SITUATED OVER THE MIDWEST SAT...SHIFTING EWD INTO THE GREAT LAKES SUNDAY WHILE SHEARING OUT. FRONTAL BOUNDARY IS GOING TO LAY ACROSS THE OHIO VALLEY. MOISTURE SURGING NWD FROM THE GULF COAST SHOULD START TRACKING CLOSER TO OUR AREA. SAT WILL BE THE DRIEST DAY FOR THE OFFICIAL END TO THE SUMMER SEASON...BUT ISOLATED STORMS ARE POSSIBLE IN THE MTNS. SUNDAY IS GOING TO BE A BIT WETTER AS THE FRONT TRACKS CLOSER BUT STILL IT LOOKS SCATTERED INSTEAD OF WIDESPREAD...BEST COVERAGE OVER THE MTNS. SO FOR THOSE PLANNING OUTDOOR ACTIVITIES BE AWARE FOR BOTH STORMS/LIGHTNING AND HOTTER TEMPS. LABOR DAY ITSELF SHOULD BE STORMY ALTHOUGH FRONT WILL BE NORTH OF US...BUT UPPER SHORTWAVE MAY PASS ACROSS THE CENTRAL APPALACHIANS INDUCING BETTER LIFT WITH INCREASED MOISTURE. THE UPPER HEIGHTS FLATTEN SOMEWHAT AS WELL. HIGHS MONDAY ARE GOING TO STILL BE VERY WARM WITH LOWER 80S MOUNTAINS TO NEAR 90 SOUTHEAST...THOUGH INCREASED HUMIDITY AND SW FLOW WILL HINDER A BIG RISE IN TEMPS. BY TUESDAY...WE ARE STILL SEEING SOMEWHAT FLATTENING OF THE RIDGE NORTH OF US...WITH NEXT UPSTREAM TROUGH MOVING ACROSS THE UPPER MISSISSIPPI VALLEY. LOOKS MORE LIKE DIURNALLY DRIVEN CONVECTION THOUGH 00Z ECMWF SHOWS WEAK IMPULSE MOVING ACROSS THE AREA TUESDAY AFTN. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... AS OF 130 AM EDT WEDNESDAY... AREAS OF MVFR TO LIFR VALLEY FOG WILL DEVELOP EARLY THIS MORNING...ESPECIALLY ALONG THE NEW AND GREENBRIER RIVER. HIGH CONFIDENCE THAT KBCB AND KLWB WILL LOWER TO LIFR VISIBILITIES FROM AROUND 08Z/4AM TO 12Z/8AM. FOG WILL BURN OFF QUICKLY AFTER 13Z AS DAYTIME HEATING AND MIXING DEVELOPS. ELSEWHERE...LITTLE OR NO IMPACT EXPECTED FROM THE RIVER VALLEY FOG WITH VFR CONDITIONS DOMINATING THROUGH THE 24 HOUR TAF PERIOD. EXTENDED DISCUSSION... A COLD FRONT WILL SINK SOUTHWARD FROM THE GREAT LAKES EARLY THURSDAY TO SETTLE ACROSS THE CENTRAL APPALACHIANS. SPOTTY SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE INTO THE WEEKEND AS WEAK DISTURBANCES PASS ALONG THE BOUNDARY. BRIEF PERIODS OF SUB VFR CONDITIONS ARE EXPECTED WITH THE PRECIPITATION. && .EQUIPMENT... AS OF 330 AM EDT WEDNESDAY ... THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WAS OUT OF SERVICE. REPAIRS WILL BE MADE LATER THIS MORNING. THE NOAA ALL HAZARDS RADIO...WXL92...ON 162.550 MHZ...HAS RETURNED TO SERVICE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...RCS LONG TERM...WP AVIATION...AMS/PM EQUIPMENT...AMS

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