Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 290540 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 140 AM EDT SUN MAR 29 2015 .SYNOPSIS... HIGH PRESSURE IN THE OHIO VALLEY WILL MOVE SOUTHEAST ACROSS THE REGION OVERNIGHT BEFORE SLIDING TO THE SOUTH ON SUNDAY. A COLD FRONT OVER THE CENTRAL UNITED STATES ON SUNDAY WILL MOVE EAST AND CROSS THROUGH THE AREA EARLY MONDAY. WEAK HIGH PRESSURE WILL FINALLY BUILD INTO THE REGION BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 855 PM EDT SATURDAY... MAIN UPDATE TO ADJUST LOW TEMPS OVERNIGHT GIVEN AN ARID PWAT OF .07 OFF THE EVENING RNK SOUNDING AND VERY LOW DEWPOINTS AHEAD OF HIGH PRESSURE BUILDING OVER THE MOUNTAINS BY DAYBREAK. THIS RIDGING SHOULD ALLOW JUST ENOUGH DECOUPLING ESPCLY VALLEYS UNDER CLEAR SKIES TO SEND MOST LOWS INTO THE TEENS WEST WITH A FEW SINGLE DIGITS POSSIBLE. BREEZE MAY STAY UP JUST LONG ENOUGH TO KEEP TEMPS FROM BOTTOMING OUT IN THE EAST BUT STILL UPPER TEENS TO LOWER 20S PIEDMONT. THUS CUTTING LOWS A CAT OR TWO IN THE WESTERN VALLEYS AND A FEW DEGREES IN SPOTS OVER THE EAST. OTHERWISE ONLY SMALL CHANGES TO REDUCE WINDS A BIT MORE LATER TONIGHT ESPCLY UNDER THE CENTER OF THE SURFACE RIDGE AROUND DAYBREAK. PREVIOUS DISCUSSION AS OF 240 PM EDT SATURDAY... 1028 MB HIGH PRESSURE OVER GREAT LAKES REGION THIS AFTERNOON WILL BUILD SOUTHEAST TONIGHT AND WILL BE CENTERED OVER THE MID ATLANTIC REGION SUNDAY. GUSTY NORTHWEST WINDS WILL GRADUALLY DIMINISH THIS EVENING AND BECOME LIGHT OVERNIGHT. PATCHY LOW STRATO CU WILL CONTINUE TO MOVE SOUTH SOUTHEAST THIS AFTERNOON AND DISSIPATE AFTER SUNSET. UNDER HIGH PRESSURE...WINDS WILL DECOUPLE OVERNIGHT AND WITH SURFACE DEWPOINTS IN THE TEENS AND SINGLE DIGITS...THE DRY AIR MASS WILL RESULT IN GOOD RADIATIONAL COOLING UNDER MOSTLY CLEAR SKIES. RECORD LOWS TEMPERATURES ARE POSSIBLE SUNDAY MORNING IN LYNCHBURG...BLACKSBURG...DANVILLE...LEWISBURG AND BLUEFIELD. (CLIMATE SECTION LISTED FOR REFERENCE AND ALSO NOTE THAT THE FROST AND FREEZE PROGRAM HAS NOT BEGUN FOR OUR FORECAST AREA.) AS THE HIGH CENTER SHIFTS SOUTHEAST...SOUTHERLY WINDS WILL DEVELOP BY EARLY AFTERNOON AHEAD OF ANOTHER APPROACHING COLD FRONT. DESPITE PLENTY OF SUNSHINE THROUGH MUCH OF THE DAY...UPPER LEVEL TROUGHING ALONG THE ATLANTIC COAST WILL LIMIT HEATING. PLAYED HIGH TEMPERATURES CLOSER TO COOLER ADJMET VALUES FROM THE THE LOWER 40S IN THE NORTHWEST MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT. && .SHORT TERM /TONIGHT THROUGH TUESDAY/... AS OF 305 PM EDT SATURDAY... EXPECT A FRONT TO MOVE ACROSS FROM THE NORTHERN STREAM SUNDAY NIGHT INTO MONDAY WITH MAINLY A THREAT OF SHOWERS. SOME COLDER AIR WILL SNEAK IN ACROSS THE ALLEGHANYS AND COULD PRODUCE SNOW...BUT NOTHING OF SIGNIFICANCE. ONCE THIS FRONT PASSES THE FLOW ALOFT STAYS A GENERAL WNW PATTERN. ANOTHER SHORTWAVE ARRIVES BY TUESDAY ALTHOUGH MAIN MOISTURE WILL STAY NORTH OF US. EXPECT MODERATING TEMPERATURES THIS PERIOD WITH LOWS AND HIGHS CLOSER TO NORMAL FOR LATE MARCH. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... AS OF 200 PM EDT SATURDAY... MODELS VARY IN TERMS OF THE SOUTHERN STREAM SYSTEM MOVING TOWARD OUR AREA BY THE END OF THE WEEK. BOTH 00Z/12Z ECMWF SHOW MORE AMPLIFICATION WITH UPPER SHORTWAVE OVER THE RED RIVER VALLEY OF TX WEDNESDAY WHICH IN A SPLIT FLOW APPEARS TO TAKE ON MORE NEGATIVE TILT HEADING INTO THURSDAY OVER THE TN VALLEY. HPC APPEARS TO BE LEANING TOWARD A BLEND OF THE TWO MODELS/ENSEMBLE APPROACH. THIS WILL DICTATE WHEN RAIN MOVES ACROSS OUR AREA. BEFORE THIS SYSTEM...SFC HIGH SHOULD WEDGE SWD BRIEFLY WEDNESDAY WITH SEASONABLY MILD DAY ON TAP. THIS HIGH DEPARTS THE MID ATLANTIC COAST THURSDAY MORNING...WITH SURGE OF MOISTURE PUSHING NWD ALONG THE BLUE RIDGE PER SE FLOW. AT THIS TIME...THINK WILL SEE DRIER AIR WITH LIMITED THREAT OF RAIN WED NIGHT BUT EXPECT AIRMASS TO MOISTEN MORE INTO THURSDAY AFTERNOON WITH MAIN LIFT STAYING WEST OF THE APPALACHIANS. STILL LOOKING AT THE CHANCE OF RAIN FROM ALONG AND WEST OF THE BLUE RIDGE...WITH POSSIBLY EWD EXTENT INTO THE SOUTHERN CWA PER FLOW OFF THE ATLANTIC EARLY ON BEFORE VEERING WINDS TURN MORE SW. HIGHS THURSDAY WILL BE MILD BUT COULD BE COOLER PER MORE CLOUDS AND RAIN CHANCES. IF THE HIGH SLOWS DOWN OR SHIFTS FURTHER NORTH...THUS ALLOWING LONGER EASTERLY FETCH...THEN TEMPS COULD BE 5-10 DEGREES COOLER OUT EAST....BUT STILL JUST NEAR NORMAL. AS WE HEAD INTO THURSDAY NIGHT-FRIDAY THE FORECAST VARIES...THOUGH THE NEW 12Z ECMWF SHOWS SIMILAR SETUP THAT THE 12Z GFS DOES WITH FRONT ORIENTATION SETTING UP IN AN EAST-WEST FASHION WITH PARALLEL FLOW ALOFT. THIS IS GOING TO KEEP THE AREA IN A UNSETTLED PATTERN WITH NEXT MAIN LOW ACROSS THE CENTRAL PLAINS FRIDAY ARRIVING OVER THE OHIO VALLEY/CENTRAL APPALACHIANS FRIDAY AFTERNOON/EVENING. THE DIFFERENCE IN THE MODELS IS THAT THE ECMWF SHOWS A STRONGER LOW MOVING MORE NORTH OVER THE GREAT LAKES...WHILE THE GFS HAS WEAKER LOW MOVING ACROSS WV INTO NRN VA. THE ECMWF SOLUTION AS SUCH HAS LESS QPF THAN THE GFS. NONETHELESS THREAT OF RAIN SHOWERS WILL CONTINUE INTO SATURDAY. THE AIRMASS BEHIND THE FRONT WILL BE COLD THOUGH THE ECWMF IS MUCH MORE AMPLIFIED AND COLDER THAN THE GFS. COULD SEE UPSLOPE SNOW SHOWERS IN THE MTNS SATURDAY NIGHT. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AS OF 135 AM EDT SUNDAY... HIGH PRESSURE OVER THE OHIO VALLEY WILL MOVE SOUTHEAST TODAY AND OFF THE CAROLINA COAST TONIGHT. A COLD FRONT WILL CROSS THROUGH THE REGION FROM THE WEST LATE TONIGHT. SURFACE WINDS WILL BE LIGHT AND VARIABLE THIS MORNING THEN INCREASE FROM THE SOUTH-SOUTHWEST THIS AFTERNOON AND EVENING. HIGHER ELEVATIONS MAY HAVE GUSTS UP TO 30 KNOTS JUST AHEAD OF THE FRONT. WINDS WILL SHIFT TO THE WEST THEN NORTHWEST BEHIND THE BOUNDARY. HIGH HIGH CLOUDS WILL SPREAD ACROSS THE AREA AHEAD OF THE FRONT...MAINLY AFTER 00Z/8PM. HIGH CONFIDENCE IN VFR CONDITIONS DURING THE TAF PERIOD. EXTENDED AVIATION FORECAST... A PERIOD OF MVFR CIGS ALONG WITH A BAND OF SHOWERS IS POSSIBLE IN THE MOUNTAINS LATE SUNDAY NIGHT AND MONDAY MORNING. THERE IS ALSO POTENTIAL FOR STRONG GUSTY WINDS BEHIND THE FRONT MONDAY AND AGAIN TUESDAY AS ANOTHER CLIPPER SLIDES ACROSS FROM THE NORTHWEST. WEAK HIGH PRESSURE SHOULD MAINTAIN MAINLY VFR CONDITIONS TUESDAY INTO WEDNESDAY WITH ONLY LINGERING MOUNTAIN UPSLOPE DRIVEN MVFR CIGS ON TUESDAY. MOISTURE WILL AGAIN INCREASE AHEAD OF A STRONGER COLD FRONT THURSDAY WITH A RETURN TO SUB-VFR CONDITIONS POSSIBLE. && .CLIMATE... AS OF 455 AM EDT FRIDAY... RECORD LOWS FOR MARCH 29: ROANOKE......19 IN 1982 BLACKSBURG...17 IN 2001 LYNCHBURG....23 IN 1923 AND 1982 DANVILLE.....23 IN 1966 BLUEFIELD....19 IN 1966 AND 1982 LEWISBURG....18 IN 1983 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...KK NEAR TERM...JH/KK SHORT TERM...WP LONG TERM...WP AVIATION...AMS CLIMATE...AMS/SK

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