Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 250634 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 234 AM EDT MON MAY 25 2015 .SYNOPSIS... HIGH PRESSURE BOTH SURFACE AND ALOFT WILL REMAIN OVER THE EASTERN UNITED STATES THROUGH MONDAY. THIS WILL ENSURE DRY WEATHER FOR THE REMAINDER OF THE HOLIDAY WEEKEND WITH TEMPERATURE AND HUMIDITY TRENDING HIGHER. MOISTURE WILL RETURN TO THE AREA BY MONDAY AND TUESDAY...WITH SHOWERS AND THUNDERSTORMS DEVELOPING TUESDAY...BECOMING MORE WIDESPREAD ACROSS THE REGION WEDNESDAY THROUGH THURSDAY. && .NEAR TERM /THROUGH TODAY/...
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AS OF 230 PM EDT SUNDAY... SOUTHERLY WINDS ON WESTERN PERIPHERY OF DEPARTING HIGH WILL HELP ADVECT A SHALLOW LEVEL OF LOW LEVEL MOISTURE INTO THE FAR SOUTHWEST PORTION OF THE FORECAST AREA...AND THIS MAY BRING A BLANKET OF STRATUS CLOUDS IN THIS REGION EARLY MONDAY MORNING. 850MB WINDS AT 15-20KTS TONIGHT WILL LIKELY HELP CREATE ANOTHER LARGE RIDGE/VALLEY SPLIT IN TEMPS. SIMILAR TO SATURDAY MORNING...WENT A FEW DEGREES ABOVE GUIDANCE FOR LOWS AT BLF AND OTHER HIGHER ELEVATION SITES...WITH LOWS BELOW GUIDANCE IN THE VALLEYS SUCH AS BURKES GARDEN. HUMIDITY BEGINS TO RETURN MONDAY AS THE EASTERN EDGE OF PWAT PLUME MOVES INTO FAR SW VA AND NW NC ON MONDAY. AS THE UPPER RIDGE AXIS MOVES EAST...AND WE COME UNDER THE INFLUENCE OF A DEEP SOUTH/SOUTHWESTERLY FLOW...WEAK DISTURBANCES WELL IN ADVANCE OF NEGATIVELY TILTED UPPER LEVEL TROUGH IN THE CENTRAL U.S. BEGINS TO ENCROACH OUR FAR SOUTHWEST AREA. THIS...COMBINED WITH SOME MODEST INSTABILITY...MAY GENERATE WIDELY SCATTERED SHOWERS/STORMS MONDAY AFTERNOON AND KEPT SMALL POPS IN THIS AREA. TEMPS SHOULD AGAIN BE A COUPLE OF DEGREES WARMER MONDAY...SO LEANED TOWARD THE WARMER GUIDANCE FOR HIGHS.
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&& .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... AS OF 230 PM EDT SUNDAY... UPPER LEVEL RIDGING WILL GRADUALLY SHIFT FARTHER EAST MONDAY NIGHT ALLOWING PWATS TO QUICKLY INCREASE FROM THE SW AS MOISTURE TRANSPORT ON DEEPENING SOUTHERLY FLOW TAKES SHAPE. THIS MAY ALLOW SHOWERS/ISOLATED STORMS TO LINGER WELL WEST OF THE BLUE RIDGE INTO EARLY TUESDAY AS MODELS SHOW A LOBE OF DEEPER MOISTURE REMAINING ALONG THE WESTERN SLOPES. REMAINING RIDGING ALOFT FINALLY DEPARTS BY TUESDAY NIGHT IN RESPONSE TO LOWERING HEIGHTS PER 5H TROFFINESS SWINGING BY TO THE NW. HOWEVER THE PERSISTENT MOISTURE AXIS TO THE WEST MAY STILL BE SLOW TO PUSH EAST GIVEN NEGATIVE TILT TO THE UPPER TROUGH AND PARALLEL SOUTHERLY FLOW ALONG THE BACK OF THE DEPARTING RIDGE. THIS MAY TEND TO HOLD THE BEST CONVECTION TO THE FAR WESTERN MOUNTAINS TUESDAY WITH COVERAGE SLOWLY SHIFTING EAST TUESDAY NIGHT AS A WEAK MID LEVEL WAVE RIDES UP FROM THE SW. THUS WILL EDGE CHANCE POPS ONLY EAST TO THE FOOTHILLS TUESDAY AFTERNOON GIVEN WEAK CAPES DESPITE INCREASING MOISTURE. APPEARS BEST COVERAGE TUESDAY NIGHT WESTERN RIDGES WHERE WILL BUMP POPS TO LOW LIKELYS FAR WEST OVERNIGHT...BUT STILL ONLY LOW CHANCE BLUE RIDGE AND POINTS EAST AS THE TROUGH TO THE WEST SHARPENS. WEAK SURFACE TROUGH ASSOCIATED WITH THE WEAKNESS ALOFT SLIDES ACROSS THE REGION WEDNESDAY...STALLING ACROSS THE EAST WEDNESDAY NIGHT. FORECAST PWATS OF 1.5-2.0 INCHES ALONG WITH CAPES OF 500-1K J/KG SHOULD COMBINE WITH COOLING ALOFT/LESS CAP TO PRODUCE MORE IN THE WAY OF WIDESPREAD SHRA/TSRA ESPCLY MOUNTAINS...AND ACROSS THE EAST WEDNESDAY AFTERNOON/EVENING WITH A WEAK LEE TROUGH. THEREFORE WILL KEEP HIGHER LIKELY POPS GOING MOUNTAINS WITH AT LEAST CHANCE COVERAGE EAST LATER IN THE DAY/EVENING. WINDS ALOFT NOT VERY IMPRESSIVE WHILE STEERING QUITE WEAK AND GIVEN HIGH MOISTURE CONTENT COULD BE MORE OF A HEAVY RAIN VS SEVERE THREAT INTO WEDNESDAY NIGHT. TEMPS TO BECOME WARM/MUGGY THROUGH THE PERIOD AS DEWPOINTS RISE INTO THE 60S AND CLOUDS INCREASE ESPCLY WEST. APPEARS OVERALL HIGHS MOSTLY 75-80 WEST AND LOW/MID 80S EAST WITH LOWS 60-65. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 145 PM EDT SUNDAY... A VERY WARM AND MUGGY PERIOD MORE REMINISCENT OF SUMMER LOOKS TO PREVAIL FOR LATE WEEK INTO NEXT WEEKEND AS A MOIST SOUTH/SW FLOW PERSISTS BETWEEN HIGH PRESSURE OFFSHORE AND UPPER TROFFINESS TO THE NW. THIS PROVIDED STRONG HEATING SHOULD RESULT IN AT LEAST DIURNAL SHOWERS AND STORMS ESPCLY OVER THE MOUNTAINS WHERE AIDED BY OROGRAPHICS AND DIFFERENTIAL HEATING. HOWEVER COVERAGE MAY BE A BIT LESS...AND PERHAPS MORE IN THE EAST THURSDAY...IN THE WAKE OF AN EARLIER PASSING SURFACE TROUGH THAT WILL PRODUCE A WEAK WEST/NW TRAJECTORY THURSDAY AFTERNOON. THIS SEEN VIA A SLIGHT DROP IN MODEL PWATS BEFORE RETURN SW FLOW TAKES SHAPE FRIDAY WHEN OVERALL FOCUS WILL BE LESS...BUT WITHOUT MUCH CAP APPEARS SOME SCATTERED CONVECTION LIKELY. UPPER HEIGHTS WILL SLOWLY FLATTEN NEXT WEEKEND AS ANOTHER 5H TROUGH STARTS TO SINK SOUTH FROM THE UPPER MIDWEST WITH ITS ASSOCIATED COLD FRONT LIKELY OOZING TOWARD THE AREA BY SUNDAY. MODELS DIFFER ON HOW FAST THIS BOUNDARY PUSHES SE WITH THE EARLIER EC MORE HUNG UP TO THE NW PER WAVES ALONG THE FRONT...WHILE THE GFS MORE BACKDOOR FASHION AND FASTER. HOWEVER APPEARS THAT THE BOUNDARY WILL BE CLOSE ENOUGH TO PRODUCE MORE WIDESPREAD SHOWERS/STORMS SUNDAY AFTERNOON ESPCLY NORTHERN/WESTERN SECTIONS...WITH MORE SCATTERING SATURDAY OUTSIDE OF THE NW WHERE MORE ORGANIZED PRE-FRONTAL BANDS COULD DROP IN LATE. OTHERWISE OVERALL TREND OF EARLY FOG TO BECOMING PC DURING THE DAY WITH MORE CLOUDS BY SUNDAY...AND DIURNAL CHANCE POPS...EXCEPT SOME LIKELY POPS WEST LATER IN THE WEEKEND. EXPECT TEMPS TO SLOWLY CLIMB EACH DAY WITH HIGHS POSSIBLY TOUCHING 90 OUT EAST OVER THE WEEKEND WITH MAINLY 80S ELSEWHERE. LOWS LOOK QUITE WARM AND MUGGY..ONLY IN THE 60S AT BEST GIVEN MOISTURE AROUND. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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AS OF 230 AM EDT MONDAY... VFR EXPECTED TO CONTINUE THROUGH THE TAF VALID PERIOD...ALTHOUGH SOME SUBTLE SIGNS OF BIGGER CHANGES TO TAKE PLACE THROUGH THE WEEK...WILL BECOME EVIDENT THIS TAF VALID PERIOD. THE UPPER RIDGE CENTERED OVER THE REGION WILL CONTINUE TO DRIFT SLOWLY EAST THROUGH TODAY...MOVING TOWARD THE COAST BY TUESDAY. A BROAD DIFFLUENT UPPER TROUGH ENCOMPASSES MUCH OF THE U.S. WEST OF THE MISSISSIPPI RIVER...AND THIS WILL BE EXPANDING FARTHER EAST THROUGH THE MID PART OF THE WEEK. A SERIES OF UPPER SHORT WAVES WILL TRACK FROM THE MID-SOUTH TO THE NORTHEAST MON-WED...EACH BREAKING DOWN THE UPPER RIDGE AND FORCING IT TO SHIFT FARTHER EAST. LOW-LEVEL MOISTURE WILL BE ON THE INCREASE WITH SOUTHWEST FLOW AROUND A BERMUDA HIGH. THIS WILL RESULT IN INCREASING CU DEVELOPMENT IN THE 040-060 RANGE MON AFTERNOON WITH PERIODS OF BKN CLOUD BASES POSSIBLE DURING THE AFTERNOON...ESPECIALLY WEST OF THE BLUE RIDGE...BUT FEEL THAT THE POTENTIAL FOR SHRA/TSRA WILL REMAIN WEST OF THE CWA TODAY. WINDS TODAY WILL BECOME SSW-SW AFT 13Z MON WITH SPEEDS 7-10KTS AND LOW END GUSTS LIKELY AT BLF/ROA/BCB BY LATE MORNING THROUGH THE AFTERNOON. MEDIUM TO HIGH CONFIDENCE IN CEILINGS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN VISIBILITIES THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE WIND SPEED/DIRECTION THROUGH THE TAF VALID PERIOD. EXTENDED AVIATION DISCUSSION... SOUTH-SOUTHWEST WINDS WILL CONTINUE TO BRING INCREASING MOISTURE LEVELS INTO THE REGION...ESPECIALLY WEST OF THE BLUE RIDGE TUESDAY. MEANWHILE...THE UPPER-LEVEL WILL BECOME INCREASINGLY FAVORABLE FOR SHOWERS/THUNDERSTORMS AS DISTURBANCES EMANATE FROM A BROAD UPPER TROUGH ACROSS THE CENTRAL/WESTERN U.S. EXPECT SCATTERED SHOWERS/THUNDERSTORMS MAINLY THROUGH THE I-77 CORRIDOR TUESDAY AFTERNOON...SPREADING FARTHER EAST ACROSS MUCH OF THE CWA WEDNESDAY THROUGH THE END OF THE WEEK. WED-THU AT THIS POINT APPEAR TO BE THE MOST ACTIVE DAYS FOR THUNDERSTORMS...WITH SOME STRONG THUNDERSTORMS AND HEAVY RAIN POSSIBLE DURING THIS TIME FRAME. THE THREAT FOR SHOWERS/THUNDERSTORMS MAY WELL LINGER FOR SEVERAL SUBSEQUENT DAYS AS A WEAK FRONTAL BOUNDARY/BAROCLINIC ZONE STALL ACROSS THE REGION WITH ADDITIONAL UPSTREAM ENERGY REMAINING IN PLACE. ASIDE FROM SHOWERS/THUNDERSTORMS...CONDITIONS SHOULD GENERALLY BE VFR OR MVFR AT WORST...BUT INCREASING LIKELIHOOD OF EARLY MORNING IFR-LIFR CONDITIONS IN BR/FG AND LOW CLOUDS AS MOISTURE LEVELS INCREASE AND LATE DAY SHOWERS LEAVE WET GROUND IN PLACE.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/PM NEAR TERM...PH SHORT TERM...JH LONG TERM...JH AVIATION...PM

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