Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 201744 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 144 PM EDT SAT SEP 20 2014 .SYNOPSIS... HIGH PRESSURE WILL WEDGE SOUTH ALONG THE EASTERN SLOPES OF THE APPALACHIANS TODAY. A PIECE OF THIS HIGH WILL BREAK OFF OVER THE TENNESSEE VALLEY ON SUNDAY AS A COLD FRONT CROSSES THE REGION FROM THE WEST...AND LOW PRESSURE MOVES UP THE SOUTHEAST COAST. MONDAY THROUGH THURSDAY...A LARGE HIGH PRESSURE SYSTEM WILL COVER MUCH OF THE EASTERN UNITED STATES. && .NEAR TERM /THROUGH TONIGHT/... AS OF 135 PM EDT SATURDAY... INCREASED CLOUD COVER IN THE NORTHWEST TO ALLOW FOR SOME MID LEVEL INSTABILITY ALTOCUMULUS TO DRIFT EAST OUT OF THE OHIO VALLEY. MADE SOME MINOR CHANGES IN TEMPERATURES FOR THIS AFTERNOON. AS OF 915 AM EDT SATURDAY... MADE SOME MINOR ADJUSTMENTS IN CLOUD COVER AS LOW CLOUDS ARE ALREADY STARTING TO MIX OUT THIS MORNING. MODIFIED TEMPERATURES FOR THE LATEST OBS AND MODEL TRENDS FOR THIS MORNING INTO THIS AFTERNOON. ENJOY YOUR SATURDAY AFTERNOON. AS OF 400 AM EDT SATURDAY... RADAR PICKING UP SOME PATCHES OF LIGHT RAIN EARLY THIS MORNING FROM CARROLL COUNTY INTO THE NORTHWEST NORTH CAROLINA MOUNTAINS. SEVERAL OBSERVATIONS ALSO REPORTING PATCHY FOG. SATELLITE PICTURES SHOWED A BAND OF CLOUDS ALONG THE APPALACHIANS FROM EASTERN NEW YORK INTO NORTHEAST GEORGIA. THESE CLOUDS ALIGNS WITH HIGH PRESSURE WEDGED DOWN THE APPALACHIANS. BUFKIT DATA HAD FOG AND DRIZZLE ENDING AND CLOUDS BECOMING SCATTERED IN MOST LOCATIONS...WITH UPSLOPE COMPONENT ENDING BY LATE MORNING. LITTLE ADDITIONAL CLOUD COVER EXPECTED THIS AFTERNOON. SURFACE LOW PRESSURE OFF THE COAST WILL BE OFF THE NORTH CAROLINA COAST BY SUNDAY MORNING. THE SWIRL OF CLOUDS AROUND THIS LOW MAY REACH THE FAR SOUTHEAST COUNTY WARNING AREA TONIGHT. BETWEEN THE NORTHEAST SURFACE WINDS AROUND THE COASTAL LOW AND THE SOUTHWEST WINDS AHEAD OF THE COLD FRONT...LOOKING FOR LITTLE TO NO LOW LEVEL CONVERGENCE. PRECIPITABLE WATER VALUES DROP BELOW ONE INCH TONIGHT. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 330 AM EDT SATURDAY... MODELS HAVE BEEN CONSISTENT OVER THE LAST 24 HOURS TAKING A GULF STREAM DISTURBANCE ALONG THE NC/VA SHORE SUNDAY MORNING TO OFF THE NEW ENGLAND COAST SUNDAY NIGHT. WITH THIS DISTURBANCE OUT OF THE WAY...A COLD FRONT WILL CROSS OVER THE REGION DURING THE DAY SUNDAY. THIS STRONG FAST-MOVING FALL FRONT WILL BE PUSHED BY AN UPPER LEVEL TROUGH TRACKING OVER THE GREAT LAKES SUNDAY. THIS FRONT AND ASSOCIATED SHOWERS IS EXPECTED TO MOVE OVER THE AREA SUNDAY AFTERNOON...EXITING THE PIEDMONT DURING THE EARLY EVENING. THERE IS A POSSIBILITY THIS FRONT WILL SLOW DOWN EAST OF THE BLUE RIDGE AS A SIGNIFICANT SHORT WAVE IS ON THE WESTERN FLANK OF THE TROUGH. ONCE THIS SHORT WAVE ROUNDS THE BASE OF THE TROUGH IN THE OHIO VALLEY...ANY CONVECTION WILL BE WELL EAST OF THE AREA. THIS SHORT WAVE WILL THEN USE ANY AVAILABLE MOISTURE TO BRING RAIN/DRIZZLE TO WESTERN SLOPES SUNDAY NIGHT INTO MONDAY MORNING. THE BULK OF THE RAINFALL WILL ACCOMPANY THE FRONT SUNDAY. WINDS ALOFT WILL ALREADY BE OUT OF THE WEST...PLACING MOST OF THE RAIN ALONG WESTERN SLOPES...UP TO A QUARTER OF AN INCH /0.25/. AS THESE STORMS TRACK EAST...THEY WILL BE MOVING INTO DRIER AIR AND ALONG WITH WESTERLY FLOW...RAINFALL AMOUNTS WILL BE REDUCED TO A TENTH OF AN INCH /0.10/. THE GFS CONTINUES TO PRODUCE RAINFALL EAST OF THE BLUE RIDGE DESPITE WESTERLY FLOW ALOFT. ALL MODELS ARE HINTING AT A BRIEF BACKING OF LOW LEVEL WINDS TO THE SOUTHWEST. THESE BACKING WINDS AND A LEE TROUGH SHOULD BE ENOUGH TO CARRY ISOLATED SHOWERS EAST OF THE BLUE RIDGE. JET DYNAMIC AND MODEST INSTABILITIES MAY PRODUCE A FEW STRONG STORMS IN THE WEST...BUT WEST WIND AND STORMS ENTERING RELATIVELY DRY AIR...SEVERE POTENTIAL IS VERY VERY LOW. ONCE THE FRONT TRACKS EAST OF THE AREA SUNDAY EVENING...AND THE UPPER LEVEL TROUGH PIVOTS TO THE EAST COAST MONDAY MORNING...COOLER DRIER AIR WILL USHER IN THE AUTUMN SEASON. AHEAD OF THE FRONT...SUNDAY TEMPERATURES WILL VARY FROM THE MID 70S TO NEAR 80F ACROSS THE MOUNTAINS TO MID TO UPPER 80S EAST OF THE BLUE RIDGE. TEMPERATURES WILL BE DEPEND ON RAINFALL TIMING. BEHIND THE FRONT...DAYTIME TEMPERATURES WILL BE AROUND 10F COOLER MONDAY AFTERNOON COMPARED TO SUNDAY. ALSO ON MONDAY...PRESSURE RISES WILL BRING BREEZY AND GUSTY CONDITIONS TO THE AREA...ESPECIALLY ALONG THE HIGHER RIDGES OF THE BLUE RIDGE. THE COLDEST OF THE AIR ARRIVES MONDAY NIGHT. WITH HIGH PRESSURE OVER THE REGION...MONDAY NIGHT TEMPERATURES WILL DIP INTO THE 40S...POSSIBLY THE UPPER 30S IN DEEP MOUNTAIN VALLEYS AS WINDS DECOUPLE. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 315 PM EDT FRIDAY... HIGH PRESSURE WILL BE IN CONTROL OF THE FORECAST REGION ON TUESDAY...STARTING THE DAY CENTERED OVER THE MID OHIO RIVER VALLEY. THE HIGH WILL MAINTAIN DRY NORTHERLY WIND FLOW ACROSS OUR AREA THAT WILL KEEP TEMPERATURES A FEW DEGREES BELOW NORMAL...WITH HIGHS HOLDING IN THE UPPER 60S TO MID 70S. THE DRY ATMOSPHERE WILL ALSO RESULT IN MOSTLY CLEAR SKIES. WE CAN EXPECT SIMILAR CONDITIONS FOR THE EARLY HALF OF WEDNESDAY... ALTHOUGH A REINFORCING COLD FRONT WILL BUILD SOUTHWARD FROM EASTERN CANADA...CROSSING NEW ENGLAND INTO THE MID ATLANTIC DURING THE EVENING...WHERE THE FRONT IS THEN EXPECTED TO STALL AS IT RUNS INTO UPPER LEVEL RIDGING ACROSS THE SOUTHEAST. WINDS WILL SHIFT MORE EASTERLY WEDNESDAY NIGHT AS HIGH PRESSURE PUSHES OFFSHORE...DRAWING AN INCREASING AMOUNT OF MARINE AIR INTO OUR REGION. AS SUCH...EXPECT INCREASED STRATUS ACROSS THE MOUNTAINS WEDNESDAY NIGHT...POSSIBLY WITH PATCHY DRIZZLE. MARINE AIR WILL ALSO SUPPORT SPOTTY LIGHT RAIN ACROSS THE PIEDMONT THURSDAY AFTERNOON. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 145 PM EDT SATURDAY... WIDESPREAD VFR CONDITIONS ARE EXPECTED THIS AFTERNOON INTO TONIGHT. FOG WILL DEVELOP AGAIN LATE TONIGHT IN THE RIVER VALLEYS. THIS WILL BRING MVFR TO IFR VISIBILITY TO KBCB/KDAN AND LYH AFTER MIDNIGHT. LIFR FOG IS POSSIBLE IN FOR KLWB SINCE SEVERAL HOURS OF CLEAR SKY ARE EXPECTED AFTER SUNSET. RIVER VALLEY FOG WILL DISSIPATE SUNDAY MORNING AFTER DAYBREAK. UPSTREAM TROUGH AND ASSOCIATED COLD FRONT WILL CROSS THE AREA SUNDAY WITH SHOWERS ASSOCIATED WITH FROPA. HIGH CONFIDENCE IN CEILINGS AND VISIBILITIES DURING THE PERIOD. MEDIUM TO HIGH CONFIDENCE IN WINDS DURING THE TAF PERIOD. EXTENDED AVIATION DISCUSSION... PASSAGE OF A COLD FRONT WILL BRING DRIER AIR TO THE REGION FOR EARLY NEXT WEEK PROMOTING 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...RCS LONG TERM...NF AVIATION...AMS/KK

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