Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 311622 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1222 PM EDT TUE MAR 31 2015 .SYNOPSIS... A DEEP LOW PRESSURE SYSTEM WILL PASS SOUTHEAST INTO THE MID ATLANTIC THIS AFTERNOON DRAGGING A MAINLY DRY FRONT ACROSS BY THIS EVENING. ANOTHER COLD FRONT WILL MOVE INTO THE REGION AND STALL THURSDAY THROUGH FRIDAY...BRINGING AN EXTENDED PERIOD OF SHOWERS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1150 AM EDT TUESDAY... VERY DRY AIRMASS IN PLACE WITH GUSTY WINDS SET TO WARM THINGS UP QUITE NICELY TODAY. AT ISSUE WILL BE FIRE WX CONCERNS. SEE FIRE WX DISCUSSION BELOW. MODIFIED TEMPS UP BASED ON LATEST TEMP TRENDS AND LACK OF CLOUDS UNTIL LATE. OVERALL...THREAT FOR SHOWERS WILL BE LIMITED AND MAINLY CONFINED TO THE WRN SLOPES OF THE ALLEGHANYS INTO WV. MAY SEE SOME SPRINKLES ACROSS THE NRN CWA THIS EVENING AND SOME ALSO OVER THE NW NC MTNS. NO OTHER MAJOR CHANGES OVERALL TO THE REST OF THE FORECAST. PREVIOUS VALID DISCUSSION... THE LOW PRESSURE SYSTEM WILL CONTINUE TO PASS ACROSS THE DELMARVA DURING THE EVENING...AND WILL DRAG A COLD FRONT ACROSS OUR AREA. HIGH PRESSURE WILL THEN BUILD IN FROM THE WEST...SETTLING ACROSS THE CENTRAL APPALACHIANS TOWARD DAWN ON THURSDAY. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... AS OF 415 AM EST TUESDAY... UPPER FLOW WILL BECOMING INCREASINGLY PROGRESSIVE THROUGH THE TIME FRAME AS THE NORTHEAST U.S./EASTERN CANADA UPPER TROUGH FINALLY LIFTS OUT. WED SHOULD BE A PLEASANT DAY AND THE BEST DAY OF THE SHORT TERM PERIOD AS WEAK HIGH PRESSURE DRIFTS ACROSS THE REGION UNDER A SHORT WAVE RIDGE. 850MB TEMPS DROP 4-5C FROM READINGS ON TUE BUT REMAINING MOSTLY IN THE 5C RANGE WHICH WITH AMPLE SUNSHINE SHOULD STILL SUPPORT NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES. WINDS WILL BE MUCH LIGHTER THAN ON TUESDAY. THE REMAINDER OF THE SHORT TERM PERIOD BECOMES MESSY AND COMPLICATED AS THE NORTHERN AND SOUTHERN STREAMS REMAIN OUT OF PHASE. DESPITE THE COMPLICATIONS...THE MEDIUM AND LONG RANGE MODELS REMAIN IN GENERAL AGREEMENT ON THE PATTERN SUPPORTING A FRONTAL SYSTEM DRIFTING INTO THE NORTHERN PART OF THE REGION...MAINLY NORTH OF I-64...LATE THURSDAY ASSOCIATED WITH A NORTHERN STREAM SHORT WAVE. THE FRONT WILL BECOME QUASI-STATIONARY ALONG OR JUST NORTH OF I-64 AWAITING THE NEXT UPSTREAM SHORT WAVE TO KICK THE FRONT FURTHER SOUTH. WITH THE ANTECEDENT HIGH PRESSURE DRIFTING OFF THE SOUTHEAST U.S. COAST EARLY IN THE PERIOD...INCREASINGLY MOIST GULF FLOW WILL OVERSPREAD THE REGION. THIS WILL SUPPORT WAVES OF PRECIPITATION ALONG THE BOUNDARY...MAINLY NORTH OF THE REGION THU...DRIFTING SOUTHWARD THROUGH THE REGION PRIMARILY FRI/FRI NIGHT...FINALLY SHIFTING SOUTH-EAST OF THE AREA EARLY SAT AS UPPER FLOW AMPLIFIES SLIGHTLY AND HIGH PRESSURE BUILDS EASTWARD FROM THE CENTRAL/SOUTHERN PLAINS. SUPERBLEND POPS WERE WAY OVERDONE FOR THU. THIS TYPE OF PATTERN OFTEN EXHIBITS SUCH CHARACTERISTICS AS MOISTURE STREAMS ACROSS THE REGION FROM THE SOUTHWEST...BUT FORCING REMAINS WELL NORTH-WEST OF THE REGION. THUS...REDUCED POPS CONSIDERABLY FOR THU FROM MODEL ADVERTISED POPS...WITH JUST SLIGHT CHANCE-LOW END CHANCE POPS FAR WESTERN AREAS...WITH LITTLE OR NO PRECIPITATION EXPECTED ACROSS THE PIEDMONT. LIKELY TO CATEGORICAL POPS WERE INTRODUCED FOR FRI- FRI NIGHT FROM WEST TO EAST AS THE UPPER FLOW AMPLIFIES PROVIDING BETTER SUPPORT FOR THE FRONTAL BOUNDARY TO FINALLY SHIFT SOUTHWARD THROUGH THE CWA. GIVEN THE REDUCED POPS FOR THU AND THE OVERALL LACK OF FORCING...EXPECT THUNDER THREAT TO REMAIN WEST OF THE ALLEGHANY FRONT AT THAT TIME. FOR FRIDAY...MOST MODELS ADVERTISE ENOUGH INSTABILITY TO SUPPORT THE CONTINUED MENTION OF THUNDER DURING THE AFTERNOON/EARLY EVENING. THE BEST INSTABILITY IS REALIZED EAST OF THE BLUE RIDGE FRI AFTERNOON/EARLY EVENING...BUT FALLS FAR SHORT OF ANY SEVERE CRITERIA AT THIS TIME. QPF IS ALSO MODEST...RANGING FROM 1 TO 1.5 INCHES WEST TO LESS THAN 1 INCH EAST THU-SAT. GIVEN THE RECENT DRY WEATHER...THIS RAINFALL WILL NOT CAUSE ANY ISSUES. AS NOTED ABOVE...WED SHOULD PROVIDE SEASONABLE TEMPERATURES. THU- FRI SHOULD SEE ABOVE NORMAL TEMPERATURES...ESPECIALLY EAST OF THE BLUE RIDGE WITH INCREASING SOUTHWEST SURFACE FLOW. AMPLE SUNSHINE THU EAST OF THE BLUE RIDGE COULD BOOST TEMPERATURES WELL INTO THE 70S THERE...WITH 50S AND 60S TO THE WEST. FRI MORNING SHOULD BE QUITE MILD WITH LOWS MAINLY IN THE 50S...EVEN NEAR 60 ACROSS THE PIEDMONT. MODEL GUIDANCE TEMPS THU-FRI APPEARED A LITTLE ON THE COLD SIDE AND WERE ADJUSTED UPWARD...ALSO FOR BETTER AGREEMENT WITH NEIGHBORING OFFICES. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 430 AM EDT TUESDAY... THE AFOREMENTIONED FRONTAL SYSTEM WILL FINALLY SHIFT SOUTH-EAST OF THE REGION SATURDAY MORNING ALLOWING FOR DRIER CONDITIONS FOR THE WEEKEND. GIVEN THAT THE UPPER FLOW IS ZONAL AND THE POST HIGH PRESSURE AREA IS OF PACIFIC ORIGIN...ONLY MODEST COOLING IS EXPECTED SATURDAY...RECOVERING TO NEAR OR ABOVE NORMAL TEMPERATURES QUICKLY SUN-MON. A FEW AREAS COULD BRIEFLY TOUCH THE FREEZING MARK EARLY SUNDAY...BUT OVERALL TEMPERATURES ARE EXPECTED TO REMAIN WELL ABOVE FREEZING THROUGH MOST OF THE PERIOD. GUSTY WINDS WILL LIKELY BE AN ISSUE BEHIND THE FRONT SATURDAY. MILD...DRY HIGH PRESSURE WILL DRIFT ACROSS THE REGION AND TO THE SOUTH SUN-MON ARRIVES FOR SUNDAY INTO MONDAY...MOVING OFFSHORE EARLY TUE. BEYOND THIS...IT APPEARS YET ANOTHER SERIES OF SHORT WAVES WILL BRING UNSETTLED CONDITIONS BACK TO THE AREA. TEMPERATURES ARE EXPECTED TO REMAIN ABOVE NORMAL. && .AVIATION /16Z TUESDAY THROUGH SATURDAY/... AS OF 745 AM EDT TUESDAY... ANOTHER CLIPPER LOW PRESSURE SYSTEM WILL PASS NORTH OF THE AREA THIS AFTERNOON...BRINGING ANOTHER ROUND OF STRONG WINDS WITH GUSTS AGAIN TOPPING 25-30 KTS AT TIMES. THIS TIME WIND DIRECTION SHOULD BE MORE SW-WSW AS OPPOSED TO WNW-NW OBSERVED MONDAY. THE BULK OF THE MOISTURE ASSOCIATED WITH THIS SYSTEM WILL TRACK WELL NORTH OF THE REGION. MODELS SEEM WAY OVERDONE IN MY OPINION IN BRINGING CLOUDS AND MEASURABLE QPF AS MUCH AS 0.10 INCH ALL THE WAY DOWN TO THE NW NC MOUNTAINS. HOWEVER...A PERIOD OF LOW END VFR OR HIGH END MVFR CIGS NOT ENTIRELY OUT OF THE QUESTION WEST OF THE ALLEGHANY FRONT DURING THE MID-LATE AFTERNOON IN ASSOCIATION WITH THE FRONTAL BOUNDARY. OTHERWISE...MOSTLY A DOWNSLOPE/DRYING SITUATION AND EXPECT VFR CIGS/VSBYS THROUGHOUT MOST IF NOT ALL OF THE TAF VALID PERIOD...ESPECIALLY EAST OF THE ALLEGHANY FRONT. WEAK HIGH PRESSURE BUILDS IN OVERNIGHT TONIGHT...RESULTING IN VFR CONDITIONS. WINDS WILL DIMINISH RAPIDLY AFTER SUNSET AND BECOME NORTHWEST. HIGH CONFIDENCE IN CEILINGS...EXCEPT MEDIUM TO HIGH CONFIDENCE MID- LATE AFTERNOON EASTERN WV AREA. HIGH CONFIDENCE IN VFR VISIBILITIES THROUGHOUT THE TAF VALID PERIOD. HIGH CONFIDENCE IN WIND SPEED/DIRECTION THROUGHOUT THE TAF VALID PERIOD. EXTENDED AVIATION FORECAST... VFR CONDITIONS EXPECTED WEDNESDAY WITH WEAK HIGH PRESSURE OVER THE REGION. A SLOW MOVING COLD FRONT WILL MOVE SOUTHEAST INTO THE AREA BY LATE THURSDAY. THE FRONT WILL TAKE A GOOD TWO DAYS TO DRIFT THROUGH THE REGION BRINGING AN EXTENDED PERIOD OF SHOWERS AND EVEN A FEW THUNDERSTORMS TO THE AREA FRIDAY ALONG WITH ASSOCIATED MVFR-IFR CIGS/VSBYS AT TIMES. IMPROVING CONDITIONS APPEAR LIKELY LATER SATURDAY AS HIGH PRESSURE STARTS TO BRING DRIER AIR IN FROM THE WEST ON GUSTY NW WINDS SATURDAY AFTERNOON. && .FIRE WEATHER... AS OF NOON EDT TUESDAY... CONDITIONS ARE BECOMING RIPE FOR FIRE GROWTH GIVEN INCREASE SW FLOW AHEAD OF THE FRONT. THIS WILL SEND TEMPS WILL INTO THE 60S...WITH LOWER 70S EAST. MIN RH WILL BE IN THE 15 TO 25 PERCENT RANGE MOST LOCATIONS...AND WINDS WILL BE SUSTAINED AT 10 TO 20 MPH...HIGHER IN THE MTNS...WITH GUSTS TO 30-40 MPH. PER COORDINATION WITH USFS IN VA AND STATE FOREST OFFICIALS IN WV...ALONG WITH SURROUNDING OFFICES WE EXPANDED THE RED FLAG WARNING TO INCLUDE THE REST OF INTERSTATE 81 CORRIDOR WEST TO SE WV...AND EXTENDED IN TIME THE RED FLAG TIL 8PM BEFORE WINDS DIMINISH AND RH RISES. ENHANCED FIRE DANGER STATEMENT REMAINS FOR AREAS EAST OF THE BLUE RIDGE IN VA...AND ALL OF NC...AS ELEMENTS ARE NOT COMING TOGETHER AS GREAT FOR A RED FLAG...BUT WILL CONTINUE TO MONITOR WINDS AND RH. FIRE OFFICIAL SHOULD ALSO WATCH FOR A WIND SHIFT LATER THIS AFTERNOON...INTO EARLY EVENING AS THE FRONT MOVES ACROSS...FROM SOUTHWEST TO WEST. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR VAZ007- 009>014-017>020-022>024-034-035. NC...NONE. WV...RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR WVZ042>044- 507-508. && $$ SYNOPSIS...NF/WP NEAR TERM...NF/WP SHORT TERM...RAB LONG TERM...RAB AVIATION...NF/RAB FIRE WEATHER...NF/WP

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