Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 300136 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 936 PM EDT FRI MAY 29 2015 .SYNOPSIS... HIGH PRESSURE OFFSHORE WILL COVER MUCH OF THE EASTERN UNITED STATES SATURDAY AND SUNDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST LATE IN THE WEEKEND...THEN SOUTH OF THE AREA BY MONDAY...RESULTING IN MORE WIDESPREAD SHOWERS AND THUNDERSTORMS INTO TUESDAY. COOLER WEATHER WITH HIGH PRESSURE WILL BUILD IN THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH SATURDAY/... AS OF 935 PM EDT FRIDAY... SHOWERS/THUNDERSTORMS RAPIDLY DISSIPATING WITH LOSS OF DAYTIME HEATING. AS OF 935 PM EDT...THE ONLY REMAINING AREA WAS OVER PORTIONS OF THE GREENBRIER VALLEY INTO THE ALLEGHANY HIGHLANDS...WHERE CONFLUENCE IN VICINITY OF DECAYING OUTFLOW BOUNDARY AND FORCED ASCENT HAS MAINTAINED SUFFICIENT UPWARD VERTICAL MOTION TO MAINTAIN STORMS A BIT LONGER THAN ELSEWHERE. A SECOND SMALL AREA APPROACHING FROM THE SOUTH TOWARD WILKESBORO, NC...WHERE BOUNDARY LAYER STILL A BIT WARMER AND NOT WORKED OVER FROM EARLIER CONVECTIVE ACTIVITY. REGARDLESS...EVEN THESE AREAS SHOULD EXPERIENCE DISSIPATION BEFORE MIDNIGHT AS LOWER LEVELS STABILIZE AND WITH NO FORCING ALOFT TO MAINTAIN UPWARD VERTICAL MOTION. PREVIOUS FORECAST FOR OVERNIGHT PERIOD STILL ON TRACK AND VERIFYING WELL. AS OF 245 PM EDT FRIDAY... UPPER RIDGE AXIS PUSHES SLIGHTLY SOUTHEAST TONIGHT AND SATURDAY BUT WILL STILL BE OVER VIRGINIA AND NORTH CAROLINA. A WEAK SURFACE FRONT EXTENDED FROM THE DELMARVA TO OHIO. DO NOT EXPECT THIS BOUNDARY TO MAKE ANY FARTHER PROGRESS SOUTH. IF THERE IS ANY LINGERING SHOWERS AND THUNDERSTORMS AFTER THE LOSS OF DAYTIME HEATING...MODELS SHOWED THE MOST LIKELY LOCATION WILL BE IN THE FAR NORTHWEST COUNTY WARNING AREA. THE SAME LOCATION HAS THE BEST CHANCE OF THUNDERSTORMS AGAIN SATURDAY AFTERNOON. PLAN PUTTING IN LITTLE TO NO CHANCE OF RAIN FROM 07/3AM THROUGH NOON/17Z SATURDAY. SIMILAR TO FRIDAY MORNING...LOCATIONS THAT HAVE RAIN THIS AFTERNOON ARE MORE LIKELY TO HAVE FOG OVERNIGHT. WILL ADD IN MORE PATCHY FOG AFTER MIDNIGHT. GUIDANCE WAS TOO WARM FOR THE LOWS FRIDAY MORNING. WILL LEAN TOWARD SOMEWHAT COOLER MET GUIDANCE FOR OVERNIGHT LOWS. EXPECT MAXIMUM TEMPERATURES FOR SATURDAY TO BE SIMILAR TO FRIDAY. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 230 PM EDT FRIDAY... HIGH PRESSURE WILL REMAIN ANCHORED OFF THE COAST OF THE CAROLINAS DURING THIS PORTION OF THE FORECAST...ALL WHILE AN UPPER LEVEL TROUGH AND SURFACE COLD FRONT PUSH EAST THROUGH THE MID-WEST. THE RESULT WILL BE INCREASING CHANCES OF MORE THAN SIMPLY DIURNALLY BASED SHOWERS AND STORMS. WE WILL GAIN INCREASED JET DYNAMICS WITH THE APPROACH OF THE TROUGH/FRONT...ESPECIALLY ACROSS WESTERN PARTS OF THE REGION. THE FRONT ITSELF WILL MOVE INTO AND ACROSS THE AREA MONDAY NIGHT. TEMPERATURES THROUGH THE PERIOD WILL TREND SLIGHTLY COOLER THANKS TO INCREASED CLOUD COVER...AND A TREND TOWARD SLIGHTLY LOWER DEW POINTS BEHIND THE FRONT MONDAY NIGHT. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 245 PM EDT FRIDAY... THE COLD FRONT WILL WASH OUT OVER OR JUST SOUTH OF THE AREA BY TUESDAY AFTERNOON. AFTER THIS POINT...THE REGION WILL START TO TRANSITION BACK A SOUTHERLY FLOW PATTERN AS A LOW/TROUGH DEVELOPS ACROSS THE LOWER MISSISSIPPI RIVER VALLEY...AND HIGH PRESSURE BECOMES CENTERED AGAIN OFF THE COAST OF THE CAROLINAS. DAYTIME HEATING ALONG WITH PIECES OF ENERGY EJECTING OFF THE LOWER MISSISSIPPI VALLEY LOW WILL HELP YIELD INCREASING CHANCE OF SHOWERS AND STORMS AGAIN BY THURSDAY INTO FRIDAY. TEMPERATURES WILL ALSO START TO TREND MILDER THURSDAY INTO FRIDAY. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... AS OF 805 PM EDT FRIDAY... BACKEDGE OF SCATTERED SHOWERS/STORMS NOW MAINLY NORTH OF HIGHWAY 460...CONTINUING TO MOVE NORTH...AND NOW SHOWING SIGNS OF WEAKENING WITH LOSS OF DAYTIME HEATING. HAVE THEREFORE REMOVED THREAT FOR ANY ADDITIONAL PRECIPITATION AT ALL TERMINAL FORECAST POINTS EXCEPT FOR KLWB...WHICH WILL LIKELY REMAIN UNDER A THREAT UNTIL AROUND 02Z/10PM. OTHERWISE...PREVIOUS FORECAST THINKING CONCERNING THE DEVELOPMENT OF MVFR OR IFR FOG LATER TONIGHT IN AREAS THAT RECEIVED RAIN EARLIER TODAY STILL SEEMS REASONABLE...AND THIS SUPPORTED BY LATEST LAMP GUIDANCE. KLWB...KLYH...AND KBCB HAVE THE GREATEST POTENTIAL FOR DEVELOPMENT OF LATE NIGHT VISIBILITY RESTRICTIONS...LESS SO AT KDAN...KBLF...AND KROA. SIMILAR TO FRIDAY MORNING...EXPECT MOST LATE NIGHT FOG TO DISSIPATE BY 13Z/9AM...TO BE QUICKLY FOLLOWED BY DEVELOPMENT OF CUMULUS WITH ONSET OF SURFACE HEATING. HOWEVER...UNLIKE FRIDAY...EXPECT SOME SUBSIDENCE NUDGING IN FROM THE SOUTHEAST SUCH THAT ANY DIURNAL REDEVELOPMENT OF SHOWERS/STORMS BY LATE MORNING/EARLY AFTERNOON EXPECTED TO BE LESS IN OVERALL COVERAGE AND MAINLY CONFINED TO SOUTHEAST WEST VIRGINIA. THEREFORE...VCTS COMMENT INSERTED INTO KBLF AND KLWB TERMINAL FORECAST POINTS AT 17Z/1PM...BUT NOT AT THE REMAINING AVIATION FORECAST POINTS. EXTENDED DISCUSSION... ON SUNDAY...A MOIST UNSTABLE AIR MASS WILL REMAIN IN PLACE ACROSS THE REGION WITH ONLY WEAK FORCING. THIS WILL RESULT IN MAINLY SLOW MOVING DIURNALLY DRIVEN DEEP CONVECTION DURING THE AFTERNOON AND EVENING HOURS FOLLOWED BY STABLE CONDITIONS AND PATCHY MVFR FOG AT NIGHT. A FRONTAL SYSTEM WILL APPROACH FROM THE NORTH SUNDAY NIGHT. THIS BOUNDARY SHOULD FINALLY SINK SOUTH INTO THE REGION BY MONDAY RESULTING IN WIDESPREAD CONVECTION...WITH ADDITIONAL ROUNDS OF SHRA/TSRA INTO AT LEAST MONDAY NIGHT BEFORE THE BOUNDARY SINKS TO THE SOUTH. THIS SHOULD MAKE FOR MORE FREQUENT PERIODS OF SUB-VFR FROM SUNDAY NIGHT INTO TUESDAY MORNING WITH LOWER CIGS/VSBY REDUCTIONS DUE TO SHOWERS/STORMS DURING THE DAY...AND IN FOG OVERNIGHT INTO THE EARLY MORNING HOURS EACH DAY. LOWER MVFR/IFR CIGS ARE LIKELY BEHIND THE FRONT ON TUESDAY AND WEDNESDAY WITH EASTERLY FLOW AND WEDGING IN PLACE RESULTING IN MVFR CEILINGS. MAY SEE ENOUGH DRYING TO BRING AN END TO THE LOWER CLOUDS AND PRECIPITATION ON THURSDAY AND FRIDAY. THESE ARE THE MOST LIKELY DAYS TO BE VFR. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS/WERT SHORT TERM...DS LONG TERM...DS AVIATION...AMS/JH/WERT

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