Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 191641 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1241 PM EDT SUN OCT 19 2014 .SYNOPSIS... A STRONG UPPER LEVEL DISTURBANCE WILL MOVE EAST ACROSS THE REGION THIS MORNING. HIGH PRESSURE WILL BUILD IN TODAY RESULTING IN DRIER WEATHER UNDER DIMINISHING WINDS. ON MONDAY AND TUESDAY... LOW PRESSURE WILL TRACK FROM THE GREAT LAKES TO OFF THE VIRGINIA COAST. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1240 PM EDT SUNDAY... CLOUD COVER IN THE WEST IS CONTINUING ITS RAPID DISSIPATION. WE EXPECT THIS TREND TO CONTINUE THROUGH THE REMAINDER OF THE AFTERNOON SO THAT BY SUNSET VERY LITTLE IN THE WAY OF CLOUD COVER IS EXPECTED TO REMAIN. HAVE MADE SOME MINOR ADJUSTMENTS TO FORECAST HIGH TEMPERATURES FOR THIS AFTERNOON. MOST OF THESE ADJUSTMENTS HAVE BEEN AN INCREASE IN VALUE BY A DEGREE OR TWO CENTRAL AND EAST...WITH VALUES ABOUT THE SAME OR A DEGREE OR TWO COOLER IN THE WEST. NO OTHER SIGNIFICANT CHANGES AT THIS TIME. AS OF 950 AM EDT SUNDAY... HAVE MADE NO MAJOR CHANGES TO THE ONGOING FORECAST. THE SAME GENERAL TREND IS STILL EXPECTED. CLOUD COVER AND ANY LINGERING LIGHT RAIN SHOWERS IN THE MOUNTAINS WILL GRADUALLY DISSIPATE TODAY AS THE LOW LEVEL FLOW WEAKENS...AND BACKS MORE WESTERLY. ALSO ARRIVAL OF DRIER AIR IN THE LOW LEVELS WILL ONLY HELP FACILITATE THIS TREND. HAVE TWEAKED HOURLY TEMPERATURE...DEW POINT AND CLOUD COVER TO ADJUST FOR CURRENT CONDITIONS AND EXPECTED TRENDS THROUGH THE EARLY AFTERNOON. AS OF 400 AM EDT SUNDAY... AN UPPER TROUGH AXIS WILL CLEAR OUR AREA THIS MORNING...WITH HIGH PRESSURE BUILDING IN ITS WAKE FROM THE NORTHWEST. CLOUDS WILL DECREASE TODAY FROM EAST TO WEST AS HIGH PRESSURE BEGINS TO SETTLE ACROSS THE AREA. SHAPED HIGH TEMPERATURES THIS AFTERNOON CLOSE TO THE ADJMAVBC WITH READINGS FROM AROUND 50 DEGREES IN THE NORTHWEST MOUNTAINS TO THE MID 60S ACROSS THE PIEDMONT WITH PLENTY OF SUNSHINE. POSTED FREEZE WARNINGS FOR EASTERN GREENBRIER COUNTY WHERE TEMPERATURES ARE EXPECTED TO FALL BELOW FREEZING MARK. FROST ADVISORIES HAD BEEN POSTED FOR PORTIONS OF THE NEW RIVER VALLEY AND SOUTHERN SHENANDOAH VALLEYS FOR MIDNIGHT TO 9 AM MONDAY MORNING. SENSITIVE OUTDOOR PLANTS MAY BE KILLED IF LEFT UNCOVERED. TONIGHT INTO MONDAY...THE CENTER OF THE SURFACE HIGH SHIFTS TO OUR EAST ALL WHILE SOUTHWEST FLOW INCREASES AT 850 MB AND HIGHER. WE ARE EXPECTING ONE OF THE COLDEST NIGHTS OF THE SEASON FOR MOST AREAS...THE COMBINATION OF WINDS AND HIGH CLOUDS MAY MITIGATE THE EXTENT OF THE COOL DOWN. LOOKS LIKE THE RIDGE TOPS STAY MILDER THAN THE VALLEYS THANKS TO CONTINUED MIXING OF WINDS AT THE HIGHER ELEVATIONS...AND THE ELEVATIONS THEMSELVES COULD BE HIGHER THAN THE TOP OF THE NOCTURNAL INVERSION. EXPANDED THE AREAL COVERAGE OF PATCHY FROST EASTWARD...ACROSS THE PIEDMONT WHERE LOCATIONS ARE CLOSEST TO THE CENTER OF THE DEPARTING SURFACE HIGH...AND WINDS ALOFT WILL BE WEAKER. FORECAST LOWS TONIGHT WILL RANGE FROM THE UPPER 20S IN THE DEEPER MOUNTAIN VALLEYS TO NEARLY 40 DEGREES AT THE RIDGE TOPS. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... AS OF 420 AM EDT SUNDAY... THE NEXT UPSTREAM TROUGH/ALBERTA CLIPPER WILL BE RAPIDLY APPROACHING THE REGION FROM THE NORTHWEST MON. COLD SFC HIGH PRESSURE WILL ALREADY BE CENTERED WELL EAST OF THE REGION AT 12Z MON ALONG THE NC COAST. SOUTHWEST SFC WINDS WILL ALREADY BE IN PLACE MON MORNING...QUICKLY ALLEVIATING ANY FURTHER CONCERNS WITH FREEZING TEMPERATURES OR FROST. ALTHOUGH THE SYSTEM WILL BE STARVED FOR MOISTURE AND MAINTAINS A TRACK N-NE OF THE REGION THROUGH THE SHORT TERM...INITIAL STRONG DYNAMICS SHOULD...AS WITH THE SYSTEM YESTERDAY...SUPPORT SCT SHOWERS INTO THE WESTERN HALF OF THE REGION...MAINLY WEST OF THE BLUE RIDGE AS EARLY AS MON AFTERNOON...CONTINUING INTO THE EVENING. AS WITH YESTERDAYS SYSTEM...THE BEST CHANCE FOR -SHRA WILL BE ACROSS THE NW-W PART OF THE CWA...MAINLY WEST OF THE ALLEGHANY FRONT...WITH LIKELY LITTLE MORE THAN -SHRA OR SPRINKLES TO THE EAST...ESPECIALLY EAST OF THE BLUE RIDGE. FOR THE REMAINDER OF THE SHORT TERM...THE FORECAST WILL BE DOMINATED BY YET ANOTHER DEEP UPPER CLOSED LOW. MODELS HAVE COME INTO CONSENSUS THAT THE UPPER LOW WILL REMAIN N-NE OF THE REGION THROUGH THE PERIOD...MEANDERING ABOUT THE NORTHERN MID-ATLANTIC THROUGH THE LATER HALF OF THE WEEK. THIS KEEPS THE BEST MOISTURE AND DYNAMICS WELL N-NE OF THE CWA. THERE ARE SUBTLE LOBES OF PVA SLATED TO ROTATE AROUND THE UPPER LOW THAT WILL ENHANCE -SHRA AT TIMES...AGAIN MAINLY ACROSS THE FAR NORTHERN PARTS OF THE CWA...AND ESPECIALLY ACROSS THE ALLEGHANYS FROM GREENBRIER DOWN TOWARD MERCER AND TAZEWELL. WITH THE REGION ON THE COLDER WEST SIDE OF THE SYSTEM...MODELS HAVE TRENDED DOWNWARD WITH 850MB TEMPS...SHOWING SOME POTENTIAL FOR POCKETS NEAR 0C ACROSS THE ALLEGHANYS...BUT MOSTLY AFTER THE BETTER MOISTURE HAS SHIFTED EAST OF THE REGION. THE LACK OF DYNAMIC COOLING AND MARGINAL 850MB TEMPS WILL ALLOW ME TO NOT MENTION ANY THREAT OF WINTER PCPN AT THIS TIME. ON THE OTHER HAND...TEMPERATURES ARE TOO COOL AND THE AIR MASS ENTIRELY TOO STABLE THROUGH THE PERIOD TO MENTION ANY THUNDER. MODEL RUN QPF IS MINISCULE THROUGH THE PERIOD...GENERALLY ON A FEW HUNDREDTHS OF AN INCH EAST OF THE BLUE RIDGE...AND MOSTLY 1/10 TO 1/4 INCH WEST OF THE BLUE RIDGE. AGAIN...MODELS CONTINUE TO TREND DOWNWARD WITH QPF AS WELL AS THE SYSTEM REMAINS MOSTLY NE OF THE REGION. THE WORK WEEK WILL CERTAINLY BE ON THE COOL SIDE WITH SLIGHTLY BELOW NORMAL TEMPERATURES EXPECTED THROUGH MUCH OF THE WEEK...THANKS TO THE PERSISTENT CYCLONIC FLOW...COOL 850MB TEMPS...NW SFC FLOW...AND COLD CORE ALOFT INDUCED STRATOCUMULUS. USED A MODEL BLEND FOR MAX/MIN TEMPS. CLOUD COVER...SHOWERS...AND TURBULENT MIXING WILL PREVENT FREEZING TEMPERATURES THROUGH THE PERIOD. && .LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 445 AM EDT SUNDAY... BENIGN WEATHER EXPECTED THROUGH THE PERIOD. THE CLOSED NEAR BAROTROPIC UPPER LOW ACROSS THE NORTHERN MID-ATLANTIC REGION WILL LIFT OUT OF THE AREA BY FRIDAY...WITH A BROAD UPPER RIDGE STRETCHING FROM THE SW DESERT STATES INTO THE MIDWEST/MID-ATLANTIC REGION BY THE WEEKEND. AN ANOMALOUS UPPER LOW IS PROGGED TO DEVELOP ALONG THE CENTRAL GULF COAST...BUT APPEARS TO BE ASSOCIATED WITH LITTLE SENSIBLE WEATHER AND AT ANY RATE REMAINS BLOCKED FROM REACHING AREAS NORTH OF THE IMMEDIATE GULF COAST THANKS TO THE WEST-EAST ORIENTED RIDGE ACROSS THE MID-LATITUDES. THUS...MOST OF THE PERIOD SHOULD BE DOMINATED BY WEAK HIGH PRESSURE AND A DRY WESTERLY FLOW. HAVE REMOVED ALL MENTION OF -SHRA AFT THU. TEMPERATURES WILL SLOWLY MODERATE THROUGH THE PERIOD AND MAY ACTUALLY BE SLIGHTLY ABOVE NORMAL BY THE END BY FRI/SAT. OVERALL...VERY PLEASANT WEATHER EXPECTED THROUGH THE PERIOD. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 730 AM EDT SUNDAY... EAST OF THE BLUE RIDGE...VFR CONDITIONS EXPECTED THROUGH THE TAF VALID PERIOD. WEST OF THE BLUE RIDGE...AND ESPECIALLY WEST OF THE ALLEGHANY FRONT...MVFR CIGS WILL LINGER THROUGH MID TO LATE MORNING...BEFORE CONDITIONS THERE ALSO IMPROVE TO VFR. STRONG SHORT WAVE HAS SHIFTED EAST...BUT UPSLOPE NW FLOW CONTINUES ACROSS THE ALLEGHANYS. CIGS ACROSS EASTERN WV...INCLUDING LWB/BLF GENERALLY IN THE 010-025 RANGE. BLF HAS BRIEFLY DROPPED TO 009...BUT THIS SHOULD BE SHORT LIVED WITH A LITTLE DAYTIME HEATING. EAST OF THE BLUE RIDGE...MAY SEE A FEW SC THROUGH 15Z...THEN SKC THROUGH THE REMAINDER OF THE TAF VALID PERIOD. WEST OF THE BLUE RIDGE...EXPECT CLOUDS TO SCT OUT IN THE 15Z-17Z TIME FRAME...WITH BLF/LWB LIKELY BEING THE LONGEST TO HOLD ONTO MVFR CIGS. WINDS NOT AS STRONG AS SAT...BUT GENERALLY WNW 8-12KTS GUSTING TO 17-22KTS THROUGH MID-AFTERNOON...THEN DIMINISHING QUICKLY TO NEAR CALM BY 23Z. WINDS WILL QUICKLY BACK TO THE SW EARLY MON. HIGH CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD. HIGH CONFIDENCE IN VSBYS THROUGH THE TAF VALID PERIOD. HIGH CONFIDENCE IN WIND DIR/SPD THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION DISCUSSION... ANOTHER UPPER LOW WILL SETTLE INTO THE REGION FROM THE NORTH LATE MONDAY AND LINGER THROUGH MID-WEEK WITH SCT -SHRA AND MOSTLY MVFR CEILINGS AND BRIEF PERIODS OF MVFR VISIBILITIES IN -SHRA. LOWER CIGS AND VSBYS WILL MAINLY IMPACT LWB/BLF/BCB THROUGH THE PERIOD. IMPROVING CONDITIONS ARE EXPECTED TOWARD THE VERY END OF THE WEEK WITH MOST VFR CONDITIONS AFTER THU. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR VAZ010>014-018>020-023-024. NC...NONE. WV...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR WVZ043-044-508. FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR WVZ507. && $$ SYNOPSIS...KK NEAR TERM...DS/KK SHORT TERM...RAB LONG TERM...DS/RAB AVIATION...KK/RAB

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