Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 211722 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 122 PM EDT SUN SEP 21 2014 .SYNOPSIS... LOW PRESSURE WAS OVER MICHIGAN WITH A COLD FRONT TRAILING INTO THE MID MISSISSIPPI VALLEY. THIS FRONT WILL MOVE EAST TODAY AND TONIGHT...AND WILL REACH THE EAST COAST BY MONDAY MORNING. MONDAY THROUGH THURSDAY...A LARGE HIGH PRESSURE SYSTEM WILL COVER MUCH OF THE EASTERN UNITED STATES. && .NEAR TERM /THROUGH TONIGHT/... AS OF 100 PM EDT SUNDAY... KFCX 88D SHOWED SOME SCATTERED SHOWERS MOVING INTO THE WESTERN PORTIONS OF FORECAST AREA. ADJUSTMENT POPS ACROSS THE FAR WEST TO ACCOUNT FOR THIS CONVECTION THIS AFTERNOON. MODIFIED TEMPERATURES WITH LATEST OBS AND TREND. RAISED HIGH IN THE EAST A FEW DEGREES WITH SUNSHINE. MORE CHANGES THIS AFTERNOON. AS OF 933 AM EDT SUNDAY... MADE SOME MINOR ADJUSTMENTS IN TEMPERATURES AND CLOUD COVER FOR THIS MORNING. LOW PRESSURE CENTER OFF THE NORTH CAROLINA COAST THIS MORNING WILL LIFT NORTH INTO TONIGHT...AS COLD FRONT IN THE OHIO VALLEY APPROACHES FROM THE WEST. THE HRRR...NAM AND HIRESW- ARW STILL KEEP THE BEST CHANCES OF CONVECTION IN THE WEST. MORE CHANGES LATER THIS MORNING... AS OF 400 AM SUNDAY... SATELLITE PICTURES AND SURFACE OBSERVATIONS SHOWED THAT FOG HAD DEVELOPED IN THE NEW AND GREENBRIER RIVER VALLEYS THIS MORNING. THE FOG WILL LIFT SHORTLY AFTER SUNRISE. TIMING OF THE FRONT REMAINS SIMILAR IN THE GUIDANCE AS PAST FEW RUNS. BULK OF SHOWERS AND THUNDERSTORMS WILL COME THROUGH THE FORECAST AREA BETWEEN 2PM/18Z AND 8PM/00Z. AMOUNT OF INSTABILITY THIS AFTERNOON WILL DEPEND ON HOW MUCH HEATING THERE IS...HOW FAST THE CLOUDS ARRIVE FROM THE WEST. MODELS HAVE ENOUGH CAPE AND SURFACE HEATING TO SUPPORT THUNDERSTORMS. MODELS ALSO CONFINE A MAJORITY OF THE PRECIPITATION TO ALONG AND WEST OF THE BLUE RIDGE. THIS SEEMS REASONABLE WITH THE LOW LEVEL WINDS STARTING FROM THE NORTH THIS MORNING AND BACKING TO THE WEST AHEAD OF THE FRONT AS HIGH PRESSURE OVER THE AREA WEAKENS. THE FRONT COMES THROUGH THE FORECAST AREA BETWEEN 00Z/8PM AND 06Z/2AM. DECENT PRESSURE RISES BEHIND THE FRONT WITH 850 MB TEMPERATURES DROPPING TO AROUND +6 IN SOUTHEAST WEST VIRGINIA BY MONDAY MORNING. EXPECTING SOME LOW LEVEL MOISTURE IN THE WESTERN UPSLOPE AREA AFTER MIDNIGHT...BUT BUFKIT FORECAST SOUNDINGS SHOWED THE MOISTURE WILL BE SHALLOW. EAST OF THE BLUE RIDGE WILL CLEAR OUT LATE TONIGHT. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... AS OF 300 AM EDT SUNDAY... AN UPPER LEVEL TROUGH WILL PIVOT ACROSS THE REGION WITH NORTHWEST FLOW AND LOW LEVEL MOISTURE KEEPING CLOUDS BANKED UP AGAINST WESTERN SLOPES THROUGH MONDAY MORNING. ONCE THIS TROUGH AXIS TRACKS TO THE MID ATLANTIC COAST DURING THE AFTERNOON...DRY AIR WILL ERODE MOUNTAIN CLOUDS WITH CLEAR CONDITIONS CONTINUING THROUGH THE REST OF THE PERIOD. DOWNSLOPE FLOW IS EXPECTED EAST OF THE BLUE RIDGE TO KEEP CLEAR SKIES THROUGH THE ENTIRE PERIOD. FOLLOWING THE PASSING OF THE UPPER LEVEL TROUGH...A SURGE OF COOLER DRIER AIR WILL MOVE OVER THE AREA. DEW POINTS WILL DROP INTO THE 40S MONDAY AFTERNOON AND CONTINUE TO LOWER INTO THE 30S ACROSS THE MOUNTAINS MONDAY NIGHT. OVERNIGHT LOWS WILL RANGE FROM THE UPPER 30S IN MOUNTAIN VALLEYS TO THE UPPER 40S IN THE PIEDMONT. TEMPERATURES WILL RUN 5F-10F COOLER THAN NORMAL MONDAY AND TUESDAY AFTERNOON. ALSO MONDAY...PRESSURE RISES WILL BRING BREEZY AND GUSTY CONDITIONS TO THE AREA...ESPECIALLY ALONG THE BLUE RIDGE. GUSTS ALONG THE BLUE RIDGE COULD TOP OUT AT 30 MPH. && .LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 100 PM EDT SUNDAY... A STRONG SURFACE HIGH OVER THE NE STATES ON THURSDAY WILL SLOWLY DRIFT WESTWARD TO THE GREAT LAKES BY THE WEEKEND. THIS WILL LEAD TO A PROLONGED EASTERLY FLOW ACROSS THE REGION. HIGH TEMPERATURES WILL BE 5-10 DEGREES BELOW NORMAL RANGING FROM THE MID TO UPPER 60S ACROSS THE MOUNTAINS TO LOWER 70S EAST OF THE BLUE RIDGE. MODELS ARE STARTING TO AGREE ON A WEAK UPPER LEVEL DISTURBANCE FORMING ACROSS THE SE STATES LATE IN THE WEEK...HOWEVER THERE IS STILL MAJOR DIFFERENCES ON PLACEMENT WHICH WILL AFFECT HOW MUCH MOISTURE CAN GET PULLED UP INTO THE REGION. THE GFS CONTINUES TO BE MUCH DRIER THAN THE ECMWF. DUE TO THE MODEL DIFFERENCES...ONLY SLIGHT CHANCE POPS IN FROM THE BLUE RIDGE EASTWARD. && .AVIATION /18Z SUNDAY THROUGH THURSDAY/... AS OF 122 PM EDT SUNDAY... A COLD FRONT ALONG THE OHIO RIVER WILL DROP SOUTHEAST THIS AFTERNOON INTO TONIGHT. SCATTERED SHOWERS AND ISOLATED THUNDERSTORM IN THE MOUNTAINS WILL SPREAD EAST THIS AFTERNOON INTO TONIGHT. LOW LEVEL WINDS SHOULD INCREASE WITH THE APPROACHING FRONT...AND GUSTS 20-25KTS ARE POSSIBLE THIS AFTERNOON INTO THIS EVENING. HIGH CONFIDENCE THAT A MAJORITY OF PRECIPITATION ALONG THE FRONT WILL CROSS THE REGION BETWEEN 18Z/2PM AND 00Z/8PM AND THAT MOST OF THE PRECIPITATION WILL BE WEST OF THE BLUE RIDGE. WINDS BECOME WEST TO NORTHWEST BEHIND THE FRONT TONIGHT. MODELS WERE SUGGESTING SOME LOW LEVEL MOISTURE WILL BANK UP AGAINST THE WESTERN SLOPS OF THE APPALACHIANS LATE TONIGHT. MVFR CEILINGS ARE EXPECTED AT KBLF AND KLWB OVERNIGHT INTO MONDAY MORNING. DRIER AIR WILL PUSH SOUTH ACROSS THE REGION MONDAY AFTERNOON INTO MONDAY EVENING. HIGH CONFIDENCES ON CEILING AND VISIBILITIES DURING TAF PERIOD. MEDIUM TO HIGH CONFIDENCE ON WIND DURING THE PERIOD. EXTENDED AVIATION DISCUSSION... HIGH PRESSURE AND DRIER AIR IN THE REGION MONDAY NIGHT THROUGH THURSDAY WILL RESULT IN MAINLY VFR CONDITIONS. RIVER VALLEY FOG WILL STILL BE POSSIBLE AT NIGHT. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS/KK SHORT TERM...KK/RCS LONG TERM...CF AVIATION...AMS/KK

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