Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 280803 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 303 AM EST FRI NOV 28 2014 .SYNOPSIS... COLD HIGH PRESSURE WILL BUILD ACROSS THE REGION TODAY REACHING THE COAST OVERNIGHT INTO EARLY SATURDAY. AS THE HIGH SLIPS OFF TO OUR SOUTHEAST DURING THE WEEKEND...TEMPERATURES WILL MODERATE SATURDAY AFTERNOON INTO SUNDAY. A SLOW MOVING COLD FRONT WILL MOVE THROUGH THE REGION LATE MONDAY INTO MONDAY NIGHT...BRINGING A CHANCE OF SHOWERS....FOLLOWED BY SOMEWHAT COLDER WEATHER BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 215 AM EST FRIDAY... BANDED SNOW SHOWERS CONTINUE OVER MUCH OF THE WESTERN UPSLOPE REGION EARLY THIS MORNING SUPPORTED BY EARLIER LOW LEVEL INSTABILITY AND STRONG NW FLOW WITHIN THE INVERSION LAYER PER EVENING RNK SOUNDING. AS THE UPPER TROUGH FINALLY LIFTS OUT THIS MORNING SHOULD SEE THE 85H COLD ADVECTION AND NW TRAJECTORY MAX OUT AROUND 12Z FOLLOWED BY A WEAKER WESTERLY COMPONENT UNDER WARMING ALOFT LATER THIS AFTERNOON. THIS IN COMBO WITH GRADUAL DRYING FROM ALOFT SHOULD FINALLY BRING SNOW SHOWERS TO AN END BUT LIKELY NOT UNTIL EARLY AFTERNOON OVER THE FAR NW WHERE GUIDANCE SHOWS THE LAST FAINT AXIS OF LOW LEVEL MOISTURE HANGING ON. MAY SEE ANOTHER INCH OR TWO ESPCLY IN BANDS FROM AROUND BLF TO WESTERN GREENBRIER CTY BUT AT THIS POINT WILL STICK WITH A SPS RATHER THAN HOIST A SHORT ADVISORY GIVEN MORE ISOLATED NATURE TO COVERAGE WITH TIME TOWARD DAWN. NW FLOW ALSO REMAINS STRONG ENOUGH TO PUSH FLURRIES OUT TO THE EASTERN SLOPES OF THE BLUE RIDGE AS WELL SO INCLUDED MENTION ALONG WITH MORE CLOUDS EARLY ON. HIGH PRESSURE TO BUILD IN FROM THE WEST THIS AFTERNOON WHICH SHOULD BRING MORE CLEARING TO THE MOUNTAINS WITH MAINLY SUNNY SKIES EAST OUTSIDE OF SOME LATE DAY CI/AC. NW WINDS WILL DIMINISH THIS AFTERNOON AS THE PRESSURE GRADIENT WEAKENS WHILE ARCTIC AIR AND MORE CLOUDS EARLY SUPPORTS LOWERING HIGHS TO ONLY AROUND 30 SE WVA AND LOW/MID 30S BLUE RIDGE. APPEARS ONLY THE FAR SOUTH/EAST WILL TOP INTO THE LOW/MID 40S GIVEN MORE INSOLATION AND WEAK DOWNSLOPE. SURFACE RIDGE AXIS SLIDES EAST ACROSS THE CWA THIS EVENING REACHING COASTAL SECTIONS OVERNIGHT. THIS WILL BRING RETURN FLOW BACK TO THE REGION WITH STEADY 85H WARMING UNDER A WEAK WAVE PASSING WELL TO THE NORTH BY MORNING. HOWEVER APPEARS LITTLE MIXING OF WARMER AIR ALOFT TO THE SURFACE WILL BE REALIZED EXCEPT UP ON THE RIDGES SO ANOTHER COLD NIGHT IN STORE. INFILTRATION OF PASSING MID/HIGH CLOUDS UNDER THE DISTURBANCE TO THE NORTH...LIKELY TO OCCUR AS MOISTURE ALOFT SPILLS EAST/SE WITHIN THE WNW FLOW ALOFT SO OVERALL CLEAR SW...TO MAINLY PC ELSW WITH MORE CLOUDINESS OVER THE NORTH. THIS MAY TEND TO HOLD TEMPS UP SOME BUT STILL APPEARS LOWS MOSTLY 20S EXCEPT PERHAPS STEADY OR RISING INTO THE 30S RIDGETOPS LATE. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... AS OF 210 AM EST FRIDAY... FROM SATURDAY THROUGH SUNDAY NIGHT...THE REGION WILL BE DOMINATED BY ZONAL FLOW ALOFT...AND SOUTHWEST FLOW...WARM AIR ADVECTION CLOSER TO THE SURFACE. THE RESULT WILL BE A PERIOD OF MODERATING TEMPERATURES AND NO PRECIPITATION FOR THE VAST MAJORITY OF THE REGION. THE ONE AREA WE WILL NEED TO WATCH FOR SOME ISOLATED SHOWERS WILL BE THE PORTION OF SOUTHEAST WEST VIRGINIA AND SOUTHWEST VIRGINIA ALONG AND NORTH OF INTERSTATE 64 WEST OF COVINGTON. THIS REGION WILL BE IN CLOSE ENOUGH PROXIMITY TO A DEVELOPING WARM FRONT ACROSS THE LOWER OHIO VALLEY THAT SOME LIGHT PRECIPITATION MAY SKIRT THIS PART OF THE FORECAST AREA. AS WE HEAD INTO MONDAY...AND EVEN MORE SO MONDAY NIGHT...A SHORTWAVE TROUGH WILL DIP SOUTHEAST TROUGH THE GREAT LAKES REGION...AND THEN INTO NEW ENGLAND. THE RESULT WILL BE INCREASE CHANCES OF PRECIPITATION AS THE FRONT APPROACHES FOR TWO REASONS. FIRST WILL BE THE SHOWERY PRECIPITATION CONCURRENT TO THE FRONT. THE SECOND REASON WILL BE A BACKING OF THE LOW LEVEL FLOW IN ADVANCE OF THE FRONT TO A SOUTHEAST ORIENTATION ACROSS THE PIEDMONT. THIS WILL PROMPT UPSLOPE STRATOFORM PATCHES OR AREAS OF RAIN ALONG AND EAST OF THE CREST OF THE BLUE RIDGE ON MONDAY NIGHT. TEMPERATURES ALONG AND BEHIND THE FRONT MAY BE COLD ENOUGH FOR SOME OF THE PRECIPITATION TO CHANGE TO OR MIX WITH SNOW OVER THE HIGHER TERRAIN ACROSS THE NORTHERN AND WESTERN PARTS OF THE AREA. && .LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 256 PM EST THURSDAY... APPROACHING COLD FRONT FINALLY PUSHES THROUGH ON MONDAY. BEST CHANCE FOR PRECIP WILL BE WEST OF THE BLUE RIDGE WITH SHOWER ACTIVITY EXPECTED TO DIMINISH IN DOWNSLOPE EAST OF THE RIDGE. HIGH PRESSURE WILL THEN AGGRESSIVELY WEDGE DOWN THE EASTERN SEABOARD ON TUESDAY...BRINGING A NOTICEABLE COOLDOWN TO OUR TEMPS. CHANCE POPS STILL WARRANTED THROUGH MIDWEEK DUE TO POSSIBLE UPSLOPE IN E/SELY FLOW. NEXT APPROACHING LOW IS A FAIRLY SHALLOW AMPLITUDE WAVE AND THIS WILL ALLOW THE SURFACE HIGH TO DRIFT TO OUR EAST AND LINGER A BIT...WITH RETURN FLOW WARMING US BACK TO NORMAL LEVELS FOR MID TO LATE WEEK. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... AS OF 1145 PM EST THURSDAY... UPPER TROUGH AXIS SHIFTING EAST OF THE REGION...BUT EMBEDDED UPSTREAM SHORT WAVES HELPING TO ALLOW NEXT SURGE OF ARCTIC AIR TO SPREAD INTO THE REGION. THE COMBINED EFFECTS OF UPSLOPE...CAA...AND THE SHORT WAVES TRIGGERING PERSISTENT BANDS OF -SHSN MAINLY WEST OF THE ALLEGHANY FRONT WITH A FEW -SHSN SPILLING OVER TO THE WEST SIDE OF THE BLUE RIDGE. WITH STRONG CAA THROUGH THE NIGHT AND YET ANOTHER WEAK EMBEDDED UPSTREAM SHORT WAVE...WOULD EXPECT THIS TO CONTINUE OVERNIGHT. JUST SCT-BKN CLOUDS AT TIMES FOR AREAS EAST OF THE BLUE RIDGE. CIGS SHOULD REMAIN MOSTLY MVFR WEST OF THE BLUE RIDGE THROUGH MID-MORNING FRI...AND AT WORST LOW END VFR CIGS EAST OF THE BLUE RIDGE...INCLUDING ROA/LYH/DAN. -SHSN WEST OF THE BLUE RIDGE WILL BRIEFLY REDUCE VISIBILITY AT TIMES TO IFR CATEGORY...MAINLY LWB AND BLF. BCB MAY SEE BRIEF PERIODS OF MVFR VSBYS IS ANY OF THE HEAVIER SNOW SHOWERS PENETRATE THAT FAR EAST. THE THREAT FOR REDUCED VISIBILITY WILL DECREASE AFT 10Z AS THE MAIN SHORT WAVE PASSES EAST OF THE REGION. ELSEWHERE...VSBYS MOSTLY VFR OVERNIGHT AND FRI. LOW CLOUDS WILL BE SLOW TO CLEAR WEST OF THE BLUE RIDGE...POTENTIALLY HANGING IN TOUGH WITH MVFR CIGS AT BLF/LWB THROUGH 18/19Z...BUT BECOMING SCT TO SKC EAST OF THE BLUE RIDGE BY 15Z FRI. ANOTHER UPPER DISTURBANCE WILL TRACK ACROSS THE NORTHERN PARTS OF THE CWA DURING THE AFTERNOON AND RESULT IN BKN-OVC CIGS MOSTLY AOA100 AND NO PCPN. WINDS NW-W THROUGH THE TAF VALID PERIOD AND REMAINING FAIRLY BRISK OVERNIGHT AND THROUGH THE FIRST HALF OF THE DAY FRIDAY WITH SUSTAINED SPEEDS OF 8-10KTS...WITH LOW END GUSTS TO 18KTS REMAINING POSSIBLE OVERNIGHT ROA/BCB/BLF. MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF VALID PERIOD. EXTENDED DISCUSSION... ARCTIC HIGH PRESSURE WILL SPREAD INTO THE REGION FRI...RETURNING ALL SITES TO VFR CONDITIONS BY AFTERNOON. SOME MID/HIGH CLOUDS WILL PASS ACROSS THE REGION WITH AN UPPER DISTURBANCE PASSING BY TO THE NORTH FRI EVENING. VFR CONDITIONS ARE EXPECTED SAT-SUN WITH A WARMING TREND. THE NEXT COLD FRONT WILL REACH THE REGION MON-TUE WITH A CHANCE OF -SHRA AND MVFR CIGS/VSBYS ALONG THE FRONT FOLLOWED BY COOLER TEMPERATURES AND POTENTIAL EASTERLY FLOW...THUS ASSOCIATED MVFR CIGS. && .EQUIPMENT... AS OF 1030 AM EST WEDNESDAY... VISIBILITY SENSOR AT KLYH...LYNCHBURG AIRPORT...WAS MALFUNCTIONING AGAIN. PARTS HAVE BEEN ORDER BUT THE REPAIR MAY NOT BE UNTIL MONDAY. THE VISIBILITY AT KLYH WILL BE AUGMENTED BY STAFF WHEN THE CONTROL TOWER IS OPEN...OTHERWISE THE VISIBILITY WILL BE MISSING. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/MBS NEAR TERM...JH SHORT TERM...DS LONG TERM...MBS AVIATION...PC/RAB EQUIPMENT...AMS

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