Area Forecast Discussion
Issued by NWS Blacksburg, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
629 FXUS61 KRNK 162312 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 712 PM EDT SAT MAY 16 2015 .SYNOPSIS...
-- Changed Discussion --
HIGH PRESSURE OFFSHORE WILL MAINTAIN A MOIST SOUTHERLY FLOW OF AIR ACROSS THE REGION THROUGH MONDAY. A COLD FRONT WILL SLOWLY APPROACH FROM THE WEST LATE MONDAY...MOVING THROUGH THE REGION TUESDAY. COOLER...DRIER AIR WILL FILTER INTO THE REGION BY THE MID PART OF NEXT WEEK BEHIND THE FRONT.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH SUNDAY/... AS OF 303 PM EDT SATURDAY... SUBTROPICAL RIDGE CONTINUES FROM THE SOUTHEAST STATES INTO THE MID- ATLANTIC REGION THIS AFTERNOON INTO SUNDAY. A SOUTHERLY FLOW OF WARM AND HUMID AIR COMBINING WITH INSTABILITY AND WEAK SHORTWAVES THIS THIS AFTERNOON GENERATING SCATTERED SHOWERS AND THUNDERSTORMS. CAPES THIS AFTERNOON VARY FROM 500 TO 1K J/KG...AND LIS AROUND MINUS 1 TO MINUS 3...WITH INCREASED PWAT ABOUT AN INCH. INTERESTING TO NOTE OFF THE 18Z SPC MESOANALYSIS OF A 800 DOWNDRAFT CAPE LOCATED TO OUR NORTHEAST. AS INDICATED BY SWODY1...THE BETTER DYNAMIC AND CHANCE FOR STRONGER TO SEVERE ARE LOCATED TO OUR NORTH AND WEST. ONE CONCERN FOR THIS AFTERNOON INTO TONIGHT WILL BE THE POTENTIAL FOR LOCALLY HEAVY RAINS WITH WEAK STEERING CURRENTS LEADING TO SLOW MOVING THUNDERSTORMS...ESPECIALLY ACROSS ACROSS THE MOUNTAINS. EXPECT MOST OF THE CONVECTION TO DIMINISH THIS EVENING WITH THE LOSS OF SOLAR HEATING. CAN NOT COMPLETELY DRIER IT OUT...BECAUSE THERE IS ANOTHER UPPER DISTURBANCE ROTATING ACROSS THE REGION OVERNIGHT INTO SUNDAY MORNING. WITH LOW LEVEL MOISTURE AND LIGHT WINDS ANTICIPATE THAT AREAS OF FOG WILL FORM OVERNIGHT ESPECIALLY IN LOCATION THAT RECEIVE RAINFALL ON SATURDAY. LOW TEMPERATURE OVERNIGHT WILL BE MILD WITH READINGS FROM THE UPPER 50S IN THE MOUNTAINS TO THE MID 60S IN THE PIEDMONT. UPPER RIDGE WILL HOLD FAST THROUGH SUNDAY BUT GRADUALLY START TO FLATTEN OUT AND SHIFT EAST AS SURFACE HIGH PRESSURE CENTERED OFF THE MID ATLANTIC COAST SURFACE SINKS FURTHER TO THE SOUTH. THE DAY TWO CONVECTION KEEPS US IN GENERAL THUNDERSTORMS SUNDAY WITH BEST DYNAMICS REMAINING TO OUR WEST. THE OROGRAPHIC FORCING WILL SERVE AS THE PRIMARY MECHANISM FOR DIURNAL CONVECTION...ALONG WITH OUTFLOW BOUNDARY INTERACTIONS AND POSSIBLY SOME WEAK UPPER SHORT WAVE ENERGY. HIGH TEMPERATURES ON SUNDAY WILL RANGE FROM THE LOWER 70S IN THE MOUNTAINS TO THE UPPER 80S IN THE PIEDMONT. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... AS OF 300 PM EDT SATURDAY... MODELS CONTINUE TO BE IN GOOD AGREEMENT DURING SHORT TERM PERIOD IN MAINTAINING A SOUTHEASTERN UPPER RIDGE AMPLIFYING INTO THE BLACKSBURG FORECAST AREA THROUGH MONDAY NIGHT BEFORE BEING GRADUALLY FLATTENED BY A SHORT WAVE TROF EXPECTED TO MOVE EAST THROUGH THE GREAT LAKES ON TUESDAY. WITH THE UPPER RIDGE HOLDING UNTIL TUESDAY...SLOWLY INCREASING HEAT AND HUMIDITY ON LIGHT SOUTHWESTERLY FLOW ALONG THE PERIPHERY OF THE UPPER RIDGE WILL CONTINUE TO SUPPORT DEVELOPMENT OF MAINLY DIURNALLY- DRIVEN SHOWERS AND THUNDERSTORMS...MOST NOTABLY IN THE MOUNTAINS WHERE THETA-E VALUES WILL BE THE HIGHEST...AND WHERE LOCALIZED FORCED ASCENT AND DIFFERENTIAL HEATING DUE TO OROGRAPHIC INFLUENCES WILL BE MAXIMIZED TO PUNCH THROUGH WEAK MID-LEVEL CAPPING INVERSION. FORECAST SOUNDINGS CONTINUE TO MAINTAIN RELATIVELY WARM TEMPERATURES IN THE MID LEVELS OF THE ATMOSPHERE ALONG WITH WEAK SHEAR INTO TUESDAY...SUCH THAT SEVERE WEATHER THREAT EVEN UP THROUGH FRONTAL PASSAGE ON TUESDAY APPEARS TO BE EXTREMELY LIMITED. CORFIDI VECTORS YIELD A SLOW...BUT SUFFICIENTLY PROGRESSIVE MOTION SUCH THAT UNLESS TRAINING ALONG AN OUTFLOW BOUNDARY AND/OR ANCHORING ON A OROGRAPHIC POINT OCCURS...FLASH FLOODING THREAT SHOULD ALSO REMAIN MINIMAL DESPITE PRECIPITABLE WATER VALUES GRADUALLY CLIMBING UP TO AND MAXING OUT IN THE 1.6 - 1.8 INCH RANGE SUNDAY INTO MONDAY. PASSAGE OF SHORT WAVE TROF AND ATTENDANT COOL FRONT LATER TUESDAY SHOULD SHOULD BRING AN END TO THREAT FOR SCATTERED SHOWERS/STORMS BY/DURING TUESDAY EVENING AS COOL ADVECTION IN WEST...AND DOWNSLOPING EAST OF THE BLUE RIDGE TAKES OVER...SETTING THE STAGE FOR DRIER AND SLIGHTLY COOLER WEATHER LATER TUESDAY NIGHT INTO THE FIRST PART OF THE LONGER TERM PERIOD. TEMPERATURES THROUGH THE PERIOD WILL CONTINUE TO BE LARGELY GOVERNED BY EXTENT OF CLOUD COVER AND INFLUENCE OF CONVECTIVE OUTFLOW BOUNDARIES...BUT NOT EXPECTED TO BE THAT FAR OFF CLIMATOLOGICAL NORMALS AREA-WIDE. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 300 PM EDT SATURDAY... SURFACE HIGH PRESSURE BUILDING IN FROM THE NORTHWEST SHOULD MAINTAIN DRY AND SLIGHTLY COOLER WEATHER FOR THE BLACKSBURG FORECAST AREA WEDNESDAY INTO AT LEAST THURSDAY MORNING. APPROACH OF YET ANOTHER SERIES OF NORTHERN STREAM IMPULSES EXPECTED TO SUFFICIENTLY BUCKLE/BACK UPPER FLOW AGAIN IN THURSDAY/FRIDAY TIMEFRAME TO SUPPORT THE DEVELOPMENT OF WIDELY SCATTERED SHOWERS OR ISOLATED THUNDERSHOWERS...MAINLY ACROSS THE SOUTHWESTERN VA INTO THE MOUNTAINS OF NW NC WHERE RETURN FLOW AND THETA-E WILL BE A BIT HIGHER. OTHERWISE...ANOTHER RETURN TO DRIER WEATHER LOOKS TO BE IN THE OFFING BY NEXT SATURDAY AS PASSAGE OF NORTHERN STREAM WAVES SUFFICIENTLY DEEPENS/REESTABLISHES UPPER TROF OVER NEW ENGLAND...SUPPORTING SURFACE HIGH PRESSURE THAT WILL SLIDE SOUTHEAST INTO NEW ENGLAND AND WEDGE SOUTHWESTWARD INTO THE MID ATLANTIC STATES. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
AS OF 640 PM EDT SATURDAY... CLUSTERS OF DEEP CONVECTION REMAIN CONFINED TO THE FAR WEST...MAINLY ALONG THE KMKJ-KBLF-KLWB CORRIDOR THIS EVENING. THIS MAINLY OUTFLOW DRIVEN AND AIDED BY OROGRAPHICS/RESIDUAL INSTABILITY SO EXPECTING COVERAGE TO LINGER AN HOUR OR TWO PAST SUNSET. THIS MAY RESULT IN PERIODS OF MVFR/IFR IN TSRA/SHRA AT BOTH KBLF/KLWB EARLY THIS EVENING BEFORE COVERAGE FADES WITH COOLING AFTER DARK. ELSEWHERE MAINLY LOOKING AT VFR WITH ONLY A POP UP SHRA POSSIBLE ALONG THE KBCB-KROA-KLYH ROUTE THIS EVENING. ONCE CONVECTION FADES SHOULD SEE A FEW HOURS OF VFR AT ALL LOCATIONS BEFORE FOG/LOW CLOUDS START TO DEVELOP ESPCLY WHERE HEAVIER RAINFALL HAS OCCURRED. THIS WOULD AGAIN IMPACT KLWB/KBLF WHERE MAY SEE VSBYS QUICKLY LOWER TO MVFR/IFR AROUND MIDNIGHT AND THEN LIFR ESPCLY AT KLWB OVERNIGHT. A BIT LOWER CONFIDENCE ELSEWHERE GIVEN ONLY SPOTTY EARLIER SHRA ALONG THE BLUE RIDGE WHERE KROA COULD BRIEFLY LOWER TO MVFR IN FOG AFTER EARLIER RAINFALL. EXPECT TO SEE SOME RADIATIVE FOG AT MOST OTHER LOCATIONS BUT DELAYED THE ONSET GIVEN CURRENT DRIER CONDITIONS AND POTENTIAL FOR ONLY BRIEF MVFR/IFR. THUS WENT THE TEMPO ROUTE FOR LOWER CONDITIONS LATER TONIGHT OUT EAST INCLUDING POSSIBLE LIFR AT KBCB AROUND DAYBREAK. SUNDAY SHOULD BRING AN ALMOST IDENTICAL PATTERN TO TODAY WITH SCATTERED...MAINLY AFTERNOON/EVENING THUNDERSTORMS...MOST NUMEROUS WEST OF THE BLUE RIDGE. SINCE COVERAGE LOOKS A BIT MORE WIDESPREAD ...SUB-VFR CONDITIONS LOOK TO OCCUR EARLIER AND LIKELY MORE WIDESPREAD AT LEAST OUT TO THE BLUE RIDGE. KDAN MAY AGAIN STAY SOUTH OF ANY CONVECTION SO LEFT OUT MENTION THERE SUNDAY AFTERNOON. FOR THE REMAINDER...APPEARS ENOUGH SHRA/TSRA TO INCLUDE WITH AN AFTERNOON PREVAILING MVFR GROUP AT MOST OTHER SITES...WITH THE EXCEPTION BEING KLYH WHERE GOING WITH MORE VICINITY COVERAGE SINCE THEY WILL BE ON THE EASTERN EDGE OF THE MORE ORGANIZED TSRA LATER SUNDAY. MEDIUM TO HIGH CONFIDENCE IN CEILINGS...VISIBILITIES AND WINDS DURING THE TAF PERIOD. EXTENDED AVIATION DISCUSSION... LATE NIGHT/EARLY MORNING FOG AND ASSOCIATED IFR-LIFR VSBYS/CIGS BECOME INCREASINGLY LIKELY SUNDAY NIGHT INTO MONDAY GIVEN THE SOUPY ATMOSPHERE IN PLACE. LATE MONDAY INTO TUESDAY...A COLD FRONT MOVES THROUGH. THUNDERSTORMS SHOULD BE MOST NUMEROUS IN COVERAGE AND STRONGEST IN INTENSITY DURING THIS TIME FRAME FOR ALL AREAS...ENDING FROM THE WEST DURING TUESDAY. LONGER PERIODS OF MVFR CIGS/VSBYS APPEAR LIKELY MONDAY-TUESDAY. BEHIND THE COLD FRONT...DRIER/COOLER CONDITIONS ARE EXPECTED WED-THU WITH MOSTLY VFR CONDITIONS AS HIGH PRESSURE SLIDES IN FROM THE NW.
-- End Changed Discussion --
&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/RAB NEAR TERM...KK SHORT TERM...WERT LONG TERM...WERT AVIATION...JH/KK/RAB

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.