Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 231146 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 746 AM EDT WED APR 23 2014 .SYNOPSIS... A COLD FRONT OVER EASTERN VIRGINIA WILL MOVE OFF THE COAST TODAY. HIGH PRESSURE OVER THE GREAT LAKES AND OHIO VALLEY WILL QUICKLY BUILD EAST PASSING OVERHEAD TONIGHT AND THURSDAY. ANOTHER COLD FRONT WILL CROSS THE AREA FROM THE WEST ON FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 430 AM EDT WEDNESDAY... DEWPOINTS ARE ON THE WAY DOWN COURTESY OF A COLD FRONT WHICH PASSED THROUGH THE AREA LAST NIGHT. THIS FRONT WILL MOVE OFF THE MID ATLANTIC COAST TODAY...PRESSURE GRADIENT BETWEEN THE DEPARTING FRONT AND HIGH PRESSURE OVER THE GREAT LAKES AND OHIO VALLEY...RESULTING IN BREEZY CONDITIONS THROUGHOUT THE DAY. THE 1022MB SURFACE HIGH OVER THE GREAT LAKES AND OHIO VALLEY IS OF CANADIAN ORIGIN...A COOL DRY CONTINENTAL AIRMASS. IN SPITE OF ITS COOL NATURE...THE LATE APRIL SUN ANGLE SHOULD HELP BALANCE SOME OF THE COLD AIR ADVECTION...YIELDING HIGHS IN THE 60S WITH THE EXCEPTION OF THE HIGHER ELEVATIONS WHICH MAY STRUGGLE TO GET ABOVE 50 DEG F. THIS COOL AIRMASS WILL SET THE STAGE FOR A CRISP NIGHT TONIGHT. WINDS WILL DIMINISH AFTER SUNSET...AND DECOUPLE AFTER MIDNIGHT AS THE SURFACE HIGH BUILDS OVERHEAD. MODEL GUIDANCE SUGGESTS THE ENTIRE CWA WILL DIP INTO THE 30S OVERNIGHT...LOWS RANGING FROM 30 DEGREES IN THE SHELTERED MOUNTAIN VALLEYS TO THE MID/UPPER 30S IN THE PIEDMONT. THIS ALSO SUGGESTS POSSIBILITY OF FROST...BUT BASED ON THE DRYNESS OF THE AIRMASS...DEWPOINTS IN THE 20S...LACK OF MOISTURE MAY PROHIBIT MUCH FROST. ATTM WILL ADVERTISE PATCHY FROST...BUT THINK THIS WILL ONLY OCCUR IN AREAS WHERE THE WINDS COMPLETELY DECOUPLE AND THERE IS ENOUGH MOISTURE TO PROMOTE FROST...SUCH AS CREEK BOTTOMS...ETC. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 AM EDT WEDNESDAY... SURFACE HIGH PRESSURE WILL QUICKLY MOVE OVER THE REGION AND OFF THE SOUTHEAST COAST ON THURSDAY. BY THE AFTERNOON...AN UPPER LEVEL RIDGE AND SOUTHERLY FLOW WILL BRING NEAR NORMAL TEMPERATURES TO THE FORECAST AREA. CLOUDS WILL INCREASE THURSDAY NIGHT WITH PREFRONTAL SHOWERS ENTERING THE WEST BY SUNRISE FRIDAY MORNING. THESE SHOWERS AND POSSIBLE A FEW THUNDERSTORMS...WILL MOVE EAST OF THE BLUE RIDGE BY EARLY AFTERNOON AND EXIT THE AREA BY SUNSET. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH START/ENDING PRECIP TIMING WITH THE GFS A COUPLE OF HOURS FAST AND THE ECM AN HOUR OR SO SLOWER. DESPITE THE RAIN...TEMPERATURES WILL BE A FEW DEGREES WARMER ON FRIDAY. NOT MUCH COLD AIR BEHIND THE FRONT WITH LOWS FRIDAY NIGHT IN THE 40S ACROSS THE WEST AND LOWER 50S EAST. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 345 PM EDT TUESDAY... MODELS START TO BECOME DIVERGENT ON SATURDAY AS TO HOW FAR SOUTH A COLD FRONT WILL PUSH FROM THE GREAT LAKES. THE GFS IS MORE AGGRESSIVE IN TAKING THE COLD FRONT ACROSS OUR REGION DURING THE AFTERNOON... WHILE THE ECMWF HAS FLIP-FLOPPED FROM ITS PREVIOUS FORECAST SOLUTION...STALLING THE FRONT NORTH OF THE OHIO RIVER. THIS REMAINS A LOW CONFIDENCE PORTION OF THE FORECAST BUT...IN EITHER CASE...BOTH MODELS HAVE OUR AREA RELATIVELY DRY THROUGH THE REMAINDER OF THE WEEKEND...WITH RAIN CHANCES INCREASING SUNDAY NIGHT AS OUR NEXT LOW PRESSURE SYSTEM DEVELOPS ACROSS THE PLAINS... BRINGING RAIN TO THE AREA ON MONDAY. EXPECT HIGHS IN THE UPPER 60S AND 70S FOR SATURDAY AND SUNDAY...WITH RAIN BRINGING COOLER TEMPERATURES IN THE LOW TO MID 60S FOR MONDAY. THE OVERNIGHTS ARE EXPECTED TO REMAIN ABOVE FREEZING MOST LOCATIONS EXCEPT PERHAPS THE DEEPER VALLEY BOTTOMS. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
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AS OF 800 AM EDT WEDNESDAY... ASIDE FOR SOME SCT-BKN LOW CLOUD ALONG THE WRN SLOPES OF THE APPALACHIANS IMPACTING BLF/LWB THIS MORNING...VFR CONDITIONS SHOULD PREVAIL THROUGH THE 24 HOUR TAF PD. WINDS TODAY WILL BE OUT OF THE NORTHWEST...SUSTAINED 12-18KTS WITH GUSTS OF 22-28KTS. WINDS WILL DIMINISH TONIGHT WITH RETURN OF LIGHT SOUTHWESTERLY FLOW THURSDAY AS HIGH PRESSURE PASSES OVHD AND OFF THE MID ATLANTIC COAST. EXTENDED AVIATION DISCUSSION... A COLD FRONT WILL CROSS THE AREA EARLY FRIDAY...WITH A BRIEF PERIOD OF MVFR RESTRICTIONS POSSIBLE AS SHOWERS/ISOLATED STORMS MOVE EAST WITH THE FRONT THROUGH THE AREA. STRONG HIGH PRESSURE BUILDS IN FRIDAY NIGHT INTO SATURDAY WITH VFR EXPECTED UNDER GUSTY NORTHWEST WINDS. WINDS DIMINISH SATURDAY NIGHT FOLLOWED BY HIGH PRESSURE PASSING OVHD SUNDAY WITH FAIR DRY WEATHER.
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&& .FIRE WEATHER... RED FLAG WARNING IN EFFECT FROM THE VIRGINIA BLUE RIDGE NORTHWARD INTO NORTH CENTRAL VA FOR STRONG NORTHWEST WINDS AND LOW HUMIDITY. WINDS TODAY WILL RANGE FROM 15 TO 20 MPH SUSTAINED...WITH GUSTS OF 25 TO 30 MPH. HUMIDITY MINIMUMS NEAR 20 PERCENT WILL BE COMMON THIS AFTERNOON. IN ADDITION...IT HAS BEEN 7 DAYS SINCE MEASURABLE RAINFALL HAS OCCURRED IN ROANOKE VALLEY AND THE IMMEDIATE BLUE COUNTIES...INCLUDING THE NEW RIVER AND SHENANDOAH VALLEYS. THIS HAS ALLOWED LEAVES AND BRUSH TO BECOME DRY AND VERY RECEPTIVE TO FIRE...10 HOUR FUEL MOISTURE NEAR 7 PERCENT. CONCERN TODAY IS FOR RAPID FIRE SPREAD IF A WILDFIRE OCCURS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...RED FLAG WARNING FROM 11 AM THIS MORNING TO 8 PM EDT THIS EVENING FOR VAZ007-009>020-022>024-032>035-047. NC...NONE. WV...NONE. && $$ SYNOPSIS...PM NEAR TERM...PM SHORT TERM...RCS LONG TERM...NF AVIATION...PM FIRE WEATHER...PM

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