Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 221930 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 330 PM EDT WED APR 22 2015 .SYNOPSIS... A COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING ACCOMPANIED BY STRONG...GUSTY WINDS AND SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. FOR THURSDAY AND FRIDAY...A DEEP UPPER LOW IN THE NORTHEAST U.S. WILL KEEP BREEZY...CHILLY CONDITIONS ACROSS THE REGION. BY THE WEEKEND...ANOTHER UPPER-LEVEL DISTURBANCE WILL BRING THE NEXT CHANCE OF SHOWERS TO THE REGION ALONG WITH CONTINUED COOL TEMPERATURES. && .NEAR TERM /THROUGH THURSDAY/... AS OF 230 PM EDT WEDNESDAY... A COLD FRONT WILL TRACK ACROSS THE REGION THIS EVENING. WINDY CONDITIONS AHEAD OF THE FRONT WILL CONTINUE TO BRING WARM AIR INTO THE REGION. HOWEVER...THIS WARM AIR IS HAVING TROUBLE WITH MOISTURE WITH SURFACE DEW POINTS REMAINING IN THE 30S THIS AFTERNOON ACROSS THE MAJORITY OF THE AREA. AS SHOWERS ADVANCE EAST INTO THE REGION...DEW POINTS ARE COMING UP INTO THE 40S...BUT ALSO COOLING TEMPERATURES. WITH ALL THIS IN MIND...STORMS ARE LOOKING ANEMIC AND SEVERE THREAT IS LOW. AREAS SOUTH OF HWY 460...ESPECIALLY EAST OF THE BLUE RIDGE...HAS WARMED INTO THE LOWER TO MID 70S THIS AFTERNOON. EVEN THOUGH DEW POINTS ARE STILL LOW...IF THE WIND COULD RELAX...SOUTHSIDE MAY SEE SOME STRONG STORMS...POSSIBLY ISOLATED SEVERE LATE IN THE DAY. THE COLD FRONT MOVES OVER THE COASTAL PIEDMONT THIS EVENING WITH COOLER DRIER AIR TO FOLLOW. TEMPERATURES DROP INTO THE 30S ACROSS THE MOUNTAINS WITH SOME DEEPER MOUNTAINS VALLEYS INTO THE LOWER 30S. A PUBLIC INFORMATION STATEMENT WAS ISSUED THIS AFTERNOON TO START THE GROWING SEASON FOR NWS BLACKSBURG COUNTY WARNING AREA. IF FROST OR A HARD FREEZE IS EXPECTED...FROST ADVISORIES OR FREEZE WARNINGS WILL BE ISSUED. SINCE A PRESSURE GRADIENT WILL REMAIN OVER THE AREA TONIGHT...CONTINUED BREEZY AND GUSTY CONDITIONS WILL DETER FROST FROM FORMING...THEREFORE NO HEADLINES WILL BE ISSUED WITH THIS FORECAST PACKAGE. ANOTHER SHORT WAVE PASSES OVER THE AREA THURSDAY. WITH DRY CONDITIONS...THE WINDS WILL ONCE AGAIN BECOME BREEZY AND GUSTY TOMORROW BUT NOT AS STRONG AS TODAY. TEMPERATURES THURSDAY AFTERNOON WILL RUN 5F-10F COLDER THAN NORMAL. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... AS OF 300 PM EDT WEDNESDAY... IT WILL BE A COLD THURSDAY NIGHT WITH OVERNIGHT LOW TEMPERATURES RANGING FROM THE UPPER 20S IN THE NORTHWEST MOUNTAINS TO THE MID 30S IN THE PIEDMONT. NORTHWEST WINDS WILL REMAIN QUITE GUSTY ESPECIALLY ACROSS THE HIGHER TERRAIN. WILL INCLUDE THE MENTION OF PATCHY FROST ACROSS THE NORTHWEST PORTION OF FORECAST AREA WHERE TEMPERATURES ARE THE COLDEST. IF WINDS RELAX ENOUGH IN THE PIEDMONT AND TEMPERATURES DROP TO LOWER MOS VALUES...ISOLATED FROST MAY BE POSSIBLE OUT EAST. BECAUSE OF AREAL COVERAGE WILL HOLD OFF ON ANY FROST ADVISORIES AT THIS TIME AND MENTION THE POTENTIAL IN THE HWO. HIGH PRESSURE WILL TRAVEL SOUTHEAST ACROSS THE APPALACHIANS FRIDAY. WITH THE UPPER LOW SHIFTING OVER THE CANADIAN MARITIMES AND WEAK UPPER LEVEL RIDGING APPROACHING FROM THE MISSISSIPPI VALLEY...HIGH TEMPERATURES FRIDAY AFTERNOON WITH INCREASING HIGH CLOUDS WILL VARY FROM AROUND 50 DEGREES IN THE NORTHWEST TO THE MID 60S IN THE PIEDMONT. BY LATE FRIDAY NIGHT...WIND SHIFT EASTERLY...DRAWING COOLER AIR AND MOISTURE OFF THE ATLANTIC OCEAN. LOW TEMPERATURES FRIDAY NIGHT WILL GENERALLY BE IN THE MID 30S IN THE MOUNTAINS TO THE MID 40S IN THE PIEDMONT. DECREASED POPS AND SLOWED THE ARRIVAL OF THE ISOLATED TO SCATTERED SHOWERS IN THE WEST FRIDAY NIGHT...WITH A SLOWER TIMING OF LOW PRESSURE SYSTEM ADVANCING EAST ACROSS THE CENTRAL PLAINS. RAIN WILL OVERSPREAD OUR AREA BY SATURDAY AFTERNOON OR EARLY EVENING. THE TIMING OF THE RAIN IS A LITTLE FASTER ON GFS COMPARED TO ECMWF. WITH FLOW OFF THE ATLANTIC AND WIDESPREAD CLOUD COVER AND RAIN...HELD ON TO HIGH TEMPERATURES COOLER THAN MOS HOLDING IN THE 50S AREAWIDE. COOL TEMPERATURES AND STABILITY OFFERED BY THE HIGH TO OUR EAST LIMITS THE POTENTIAL FOR THUNDERSTORMS. PTYPE BECOMES SHOWERS LATE SATURDAY NIGHT AS THE LOW PRESSURE SYSTEM PASSES EAST OF THE APPALACHIANS...MOVING OFFSHORE ON SUNDAY. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 300 PM EDT WEDNESDAY... THE NORTH-ATLANTIC OSCILLATION IS PROGGED TO BE IN A NEGATIVE PHASE ...WHICH TRANSLATES TO BELOW-NORMAL HEIGHTS OVER THE EAST. A WAVY BACK DOOR COLD FRONT WILL REMAIN ACROSS THE REGION SUNDAY...BRINGING COOLER AIR INTO THE AREA FOR THE AFTERNOON INTO MONDAY. A STRONGER SURFACE WAVE OF LOW PRESSURE TRACKS ACROSS THE TENNESSEE VALLEY TO THE CAROLINA TUESDAY INTO WEDNESDAY. THIS WAVE WILL HAVE MORE MOISTURE AND DYNAMICS TO BRING SOME HEAVY RAIN AND STRONG STORMS TO THE REGION. TEMPERATURES THROUGH THE PERIOD WILL REMAIN COOLER THAN NORMAL WITH READINGS MAINLY FROM THE UPPER 50S TO THE LOWER 60S ACROSS THE MOUNTAINS TO THE MID TO UPPER 60S IN THE EAST. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... AS OF 130 PM EDT WEDNESDAY... BROAD UPPER TROUGH CENTERED OVER THE GREAT LAKES WILL CONTINUE TO DOMINATE THE WEATHER ACROSS THE EASTERN U.S. THROUGH THE PERIOD. MAIN FOCUS THIS AFTERNOON WILL BE ON A STRONG SHORT WAVE PROGGED TO TRACK THROUGH THE BASE OF THE TROUGH ACROSS OUR REGION THIS AFTERNOON. WINDS WILL BE THE MAIN ISSUE THIS AFTERNOON...WITH A STRONG GRADIENT AND LOW LEVEL JET PERSISTING INTO THIS EVENING. MANY LOCATIONS WILL SEE SW-W WINDS 15-25KTS WITH GUSTS 30-40KTS IN THE 18Z-23Z TIME FRAME...VEERING MORE TO THE WNW AFTER 00Z BEHIND THE SHORT WAVE AND DECREASING INTO THE 10-15KTS WITH GUSTS 20-25KTS OVERNIGHT ACROSS THE MOUNTAINS. CIGS EXPECTED TO REMAIN MAINLY VFR...BOTTOMING OUT MOSTLY IN THE 040-050 RANGE...EXCEPT IN UPSLOPE AREAS BLF-LWB WHERE CIGS MAY DROP INTO THE 020-030 RANGE DURING THE AFTERNOON. STRONG DYNAMICS ASSOCIATED WITH THIS SHORT WAVE MAY OVERCOME THE SFC DRYNESS AND RESULT IN ELEVATED CONVECTION THIS AFTERNOON WITH BRUNT OF THE STRONGEST CONVECTION EXITING THE AREA BY 22Z. WITH A 50-60KT WESTERLY LLJ ASSOCIATED WITH THE SHORT WAVE...ANY CONVECTION COULD BRING THESE STRONG WINDS DOWN TO THE SFC. MODEST INSTABILITY WILL ALSO BE CAPABLE OF SUPPORTING SMALL HAIL IN THE STRONGER STORMS... ESPECIALLY CONSIDERING THE VERY COLD TEMPERATURES ALOFT. LOW CONFIDENCE FOR KEEPING VCTS AT BLF/LWB/BCB/ROA/ AS PREFRONTAL SHOWERS HAVE TRACKED ACROSS THE AREA. SOUTH OF HWY 460 AND INTO THE PIEDMONT (LYH/DAN) WILL HAVE A BETTER THREAT OF VCTS WITH ABUNDANT SUNSHINE AND INCREASING MOISTURE. HOWEVER...LOW LEVEL SHEAR MAY BE TO STRONG FOR ORGANIZED THUNDERSTORM TO DEVELOP. MEDIUM TO HIGH CONFIDENCE IN CIGS AND VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF VALID PERIOD. LOW CONFIDENCE IN THUNDER POTENTIAL. EXTENDED AVIATION DISCUSSION... FRONT WILL EXIT TONIGHT WITH HIGH PRESSURE BUILDING INTO THE REGION FROM THE WEST THU-FRI. SOME GRADIENT REMAINS BETWEEN DEPARTING FRONT AND HIGH TO THE WEST THURSDAY AND POSSIBLY FRIDAY...SO GUSTY WINDS WILL REMAIN MAINLY DURING THE DAYTIME. OVERRUNNING CLOUDS WORK INTO THE AREA FRIDAY AHEAD OF A WARM FRONT. BY SATURDAY...ENOUGH MOISTURE TO ALLOW FOR SHOWERS AND MVFR WITH BEST FORCING ACROSS THE CAROLINAS. THIS WILL BE POSSIBLE INTO SUNDAY MORNING BEFORE THE SYSTEM EXITS AND SOME IMPROVEMENT IN CIGS STARTS TO OCCUR LATER SUNDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR VAZ007-009>020- 022>024-033>035. NC...WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR NCZ001-002-018. WV...NONE. && $$ SYNOPSIS...RCS NEAR TERM...RCS SHORT TERM...KK LONG TERM...KK AVIATION...RCS

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