Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 230943 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 443 AM EST SUN NOV 23 2014 .SYNOPSIS... A WARM FRONT WILL GRADUALLY SPREAD RAIN INTO THE REGION FROM THE SOUTH INTO EARLY THIS AFTERNOON. THE RAIN MAY BE HEAVY AT TIMES THIS EVENING AND EARLY TONIGHT...AND WINDS WILL BECOME QUITE GUSTY ACROSS THE MOUNTAIN EMPIRE REGION AND OTHER HIGH ELEVATIONS WEST OF THE BLUE RIDGE. UNSEASONABLY WARM CONDITIONS ARE EXPECTED MONDAY IN THE WAKE OF THIS SYSTEM...BEFORE A COLD FRONT MOVES THROUGH TUESDAY...RETURNING TEMPERATURES TO BELOW NORMAL FOR THE REST OF THE WEEK. THERE IS THE POTENTIAL FOR A COASTAL STORM TO IMPACT PARTS OF THE MID ATLANTIC FOR MID WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 330 AM EST SUNDAY... EVERYTHING SEEMS TO BE UNFOLDING AS ADVERTISED AS PCPN TO OUR SOUTH IS ADVANCING TOWARD THE REGION AHEAD OF A WARM FRONT ATTACHED TO A DEVELOPING LOW IN THE MISSISSIPPI VALLEY. DRY AIR WILL HINDER PROGRESS OF PCPN AS IT ENTERS THE REGION...BUT EXPECT IT WILL PASS THE VA/NC LINE DURING THE MORNING AND OVERSPREAD THE REMAINDER OF THE AREA THIS AFTERNOON. PCPN WILL BE BIASED WITH HEAVIEST AMOUNTS EXPECTED ACROSS THE PIEDMONT AND LESSER AMOUNTS AS YOU GO FURTHER WEST OF THE BLUE RIDGE. THE BIGGEST CONCERN THROUGH THE NEAR TERM IS THE DEVELOPING LOW LEVEL SELY JET WHICH IS EXPECTED TO PEAK AOA 70KTS JUST TO OUR WEST ROUGHLY FROM 5PM TO 1AM. THE COUNTIES OF TAZEWELL AND SMYTH IN VA AND MERCER IS WV ARE KNOWN TO BE SUSCEPTIBLE TO STRONG WINDS TRANSLATING TO LOWER ELEVATIONS IN THIS TYPE OF SITUATION SO WILL RAISE A WIND ADVSY FOR THESE LOCATIONS IN ANTICIPATION OF GUSTS AROUND 50MPH. HOWEVER...EXPECTING WINDS NOT TOO FAR BELOW CRITERIA FOR OTHER AREAS OF THE WESTERN SLOPES SO ADVISORY MAY NEED TO BE EXPANDED IF THE SITUATION UNFOLDS WITH SLIGHTLY STRONGER WINDS. ONCE THE WARM FRONT SURGES THROUGH EARLY TONIGHT A PRONOUNCED DRY SLOT WILL WORK IN FROM THE WEST AND SHOULD RAPIDLY TAPER PRECIPITATION AFTER MIDNIGHT. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 430 AM EST SUNDAY... BROAD UPPER LEVEL 500H TROUGH WILL ENCOMPASS MUCH OF THE CENTRAL CONUS MONDAY AND TUESDAY WITH COOLER AIR REMAINING WEST OF THE MOUNTAINS MONDAY...THEN ADVECTING EAST OF THE MOUNTAINS TUESDAY AS THE UPPER TROUGH PUSHES A DRY COLD FRONT OVER AND EAST OF THE MOUNTAINS DURING THE PERIOD. BAROCLINIC ZONE WILL THEN SET-UP ALONG THE EAST COAST AND WILL BECOME THE FOCUS FOR AREA OF LOW PRESSURE TO DEVELOP ALONG THE GULF STREAM TUESDAY NIGHT AND MOVE NORTHEAST NEAR THE MID ATLANTIC COAST WEDNESDAY. IN THE WAKE OF SUNDAY NIGHTS WARM FRONTAL RAIN...FORECAST AREA WILL BE IN THE DRY SLOT...WARM SECTOR SOUTHERLY WINDS PROVIDING A BREEZY BUT MILD DAY MONDAY. 1000-500MB THICKNESS VALUES OF 565-570DM AND 850H TEMPS OF +10 DEG C SUPPORT SURFACE TEMPERATURES WELL INTO THE 60S MONDAY...POSSIBLY TESTING THE LOWER 70S ACROSS SOUTHSIDE VA AND THE PIEDMONT. UNTIL SURFACE FRONT CROSSES THE MOUNTAINS LATE IN THE DAY...FORECAST AREA SHOULD REMAIN IN THE WARM SECTOR/DRY SLOT WITH MORE SUN THAN CLOUDS. MONDAY NIGHT INTO TUESDAY...THICKNESSES DROP BEHIND PASSING COLD FRONT. ASIDE FOR SOME MOUNTAIN SHOWERS...LITTLE IN THE WAY OF MOISTURE ASSOCIATED WITH THE FRONT SO BIGGEST CHANGE WILL BE A SHIFT IN WIND DIRECTION FROM SOUTH TO WEST...850 TEMPS TAKING ABOUT A 10 DEGREE TUMBLE. TEMPERATURES TUESDAY WILL RETURN TO NOVEMBER NORMALS WITH HIGHS IN THE MU40S MTNS TO LM50S SOUTHSIDE VA AND NC PIEDMONT. WEAK AREA OF HIGH PRESSURE OVER THE AREA TUESDAY AND TUESDAY NIGHT WILL ENSURE MAINLY DRY CONDITIONS...ALTHOUGH MID/UPPER LEVEL CLOUDS WILL BE ON THE INCREASE. MODELS ARE IN AGREEMENT THAT AN AREA OF LOW PRESSURE WILL DEVELOP JUST OFF THE SOUTH CAROLINA COAST TUESDAY NIGHT VCNTY OF THE BAROCLINIC ZONE. TRACK/STRENGTH OF THIS FEATURE WILL DEPEND ON OVERALL RESPONSE TO DYNAMIC FORCING FROM SHORT WAVE ENERGY ARRIVING VIA THE UPPER LEVEL TROF...MODELS TRENDING STRONGER AND MORE AMPLIFIED WITH THIS FEATURE WITH TIME. AT THE VERY LEAST CLOUDS WILL OVERSPREAD THE ENTIRE FORECAST BY TUESDAY NIGHT. QUESTIONS IS WHETHER THE MOISTURE WILL BECOME DEEP ENOUGH THIS FAR WEST FROM THE COAST FOR PRECIPITATION. ATTM IT APPEAR GREATER THAN 50 PERCENT PROBABILITY FOR RAIN TO DEVELOP ALONG AND EAST OF HIGHWAY 29 LATE TUESDAY NIGHT. IF PRECIPITATION EXTENDS ALL THE WAY TO THE BLUE RIDGE...TEMPERATURES MAY BE COLD ENOUGH ON THE WESTERN EDGE OF THIS SYSTEM TO HAVE SNOW OR A RAIN SNOW MIX. UNTIL A BETTER FIX ON STORM TRACK CAN BE ESTABLISHED...QPF WILL REMAIN IN QUESTION. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 130 PM EST SATURDAY... TWO DISTINCT SYSTEMS HAVE THE POTENTIAL FOR BRING SOME PRECIPITATION TO PARTS OF THE AREA DURING THIS SEGMENT OF THE FORECAST. THE FIRST ITEM OF INTEREST IS A LOW PRESSURE WAVE MOVING NORTHWARD ALONG A BAROCLINIC ZONE THAT WILL BE POSITIONED ALONG THE COAST DURING THE WEDNESDAY AND WEDNESDAY NIGHT TIME PERIOD. THE VARIOUS MODELS ARE STILL INCONSISTENT WITH EACH OTHER...AND WITH THEIR OWN PREVIOUS MODEL RUNS REGARDING THE TIMING...TRACK AND ASSOCIATED PRECIPITATION WITH THIS FEATURE. YESTERDAY...THE ECWMF WAS THE ONLY OPERATIONAL MODEL RUN THAT HINTED AT PRECIPITATION SKIRTING THE EASTERN EXTENT OF THE FORECAST AREA. TODAY...ITS SOLUTIONS IS MORE ROBUST ON THIS SCENARIO WITH PRECIPITATION NOW THE WHOLE WAY WEST TO EASTERN KENTUCKY. TODAY...THE GFS SOLUTION IS ONLY SLIGHTLY MORE ROBUST AS COMPARED TO THE ECWMF FROM YESTERDAY...BUT STILL...HAS ALL BUT OUR SOUTHEAST WEST VIRGINIA COUNTIES WITH AT LEAST 0.01 PRECIP. THE CANADIAN SOLUTION KEEPS THE SYSTEM FARTHER OFF THE COAST WITH NOT A DROP OF PRECIPITATION REACHING THE FORECAST AREA. OUR FORECAST FROM YESTERDAY REFLECTED A MODEL BLEND CONSENSUS THAT WAS MORE IN LINE WITH THE WETTER ECWMF SOLUTION. GIVEN BOTH THE GFS AND ECWMF ARE WETTER FOR THE REGION...AND THE MODEL BLEND CONSENSUS IS ALSO WETTER ACROSS THE REGION...HAVE FOLLOWED SUIT IN THE FORECAST. PRECIPITATION CHANCES FOR WEDNESDAY HAVE BEEN INCREASED TO REFLECT 50 PERCENT IN THE EAST...WITH 20 TO 25 PERCENT IN THE WEST. SURFACE AND LOW LEVEL THERMAL PROFILES SUGGEST MAINLY A SNOW OR RAIN/SNOW FORECAST ACROSS THE MOUNTAINS ON TUESDAY...WITH PRIMARILY RAIN ACROSS THE PIEDMONT. WEDNESDAY NIGHT...COLDER AIR ARRIVING ON THE BACKSIDE OF THE DEPARTING SYSTEM WILL ALLOW FOR MORE LIGHT SNOW...BUT WITH THE SYSTEM EXITING...MUCH LESS COVERAGE. OUT NEXT POTENTIAL WEATHER MAKER WILL BE ASSOCIATED WITH A SHORTWAVE TROUGH THAT ZIPS THROUGH THE OHIO VALLEY AND MID-ATLANTIC REGION DURING THE THURSDAY AND THURSDAY NIGHT TIME PERIOD. BOTH THE GFS AND ECWMF SOLUTIONS HAVE CHANGED COMPARED TO THEIR -24 HOUR COUNTERPARTS. PRIOR...MODEL SOLUTIONS WERE HINTING AT A MORE PROLONGED CLOSED LOW STRENGTHENING OVER THE CENTRAL APPALACHIANS WITH A MORE PROFOUND SHOT OF COLDER AIR IN ITS WAKE. THE LATEST SOLUTIONS OFFER A MORE GLANCING BLOW OF ENERGY ACROSS THE AREA...WITH THE COLDER AIR NOT HAVING AS MUCH CHANCE TO MAKE THE TURN SOUTH PRIOR TO ZONAL FLOW DEVELOPING IN THE WAKE OF THE PASSAGE OF THE SHORTWAVE TROUGH. WHILE THE FORECAST WILL STILL OFFER SOME ISOLATED TO SCATTERED RAIN/SNOW SHOWERS ACROSS PARTS OF SOUTHEAST WEST VIRGINIA AND NEIGHBORING COUNTIES OF SOUTHWEST VIRGINIA THROUGH THURSDAY NIGHT...THE TEMPERATURE FORECAST FROM THURSDAY THROUGH SATURDAY WILL BE A BIT MILDER THAN WHAT AS OFFERED IN THE PREVIOUS PACKAGE. && .AVIATION /09Z SUNDAY THROUGH THURSDAY/... AS OF 1230 AM EST SUNDAY... MODELS CONTINUE TO BE IN DECENT AGREEMENT IN HANDLING OF UPCOMING SYSTEM. STILL ANTICIPATE VFR CONDITIONS THROUGH SUNDAY MORNING BEFORE AIRMASS MOISTENS UP AHEAD OF A STORM SYSTEM MOVING ACROSS THE MID MISS VALLEY BRING A WARM FRONT ACROSS BY SUNDAY NIGHT. CIGS WILL LOWER TO MVFR BY MIDDAY/EARLY AFTERNOON AT MOST SITES WITH LIGHT RAIN FOLLOWING CLOSE BEHIND. EXPECT PERIODS OF MDT AND HEAVY RAIN FROM THE BLUE RIDGE EAST THIS EVENING INTO TONIGHT... ALONG WITH TEMPO IFR CONDITIONS. CONTINUING TO MONITOR POTENTIAL LOW LVL WIND SHEAR AS LOW LEVEL JET INCREASES TO AOA 60KTS BY LATE AFTERNOON. WILL NOT MENTION IN THIS PACKAGE BUT WILL INCLUDE WITH THE 12Z ISSUANCE IF NEEDED. LIGHT WINDS THIS EVENING WILL BECOME SOUTHWEST TO SOUTHEAST AND GUSTY SUNDAY. WINDS AT BLF MAY STAY UP A BIT TONIGHT AS THE INFLUENCE OF APPROACHING LOW PRESSURE AND WARM FRONT START TO BE FELT. EXTENDED DISCUSSION... RAIN AND WIND CONTINUE WITH MVFR TO IFR CONDITIONS SUNDAY NIGHT. A BRIEF RETURN TO VFR DURING MONDAY OUTSIDE OF THE MOUNTAINS AS A DRY SLOT DEVELOPS BETWEEN THE EXITING FRONT FROM SUNDAY AND THE NEXT UPSTREAM COLD FRONT. MONDAY INTO TUESDAY LOOK TO FEATURE QUITE A BIT OF WIND. NW FLOW INTO MAY KEEP SUB VFR CIGS INTO BLF AND POSSIBLE LWB...WITH VFR TO THE EAST. ANOTHER STORM SYSTEM IS EXPECTED TO MOVE UP THE SOUTHEAST COAST BY WEDNESDAY INTO THURSDAY WHICH MAY BRING WINTRY PRECIP TO THE AREA ALONG WITH SUB VFR AT ALL SITES. && .EQUIPMENT... AS OF 215 PM EST FRIDAY... THE VISIBILITY SENSOR AT KLYH...LYNCHBURG AIRPORT...WILL BE OUT OF SERVICE UNTIL PARTS ARRIVE TO REPLACE THE SENSOR. UNTIL THEN THE VISIBILITY WILL ONLY BE REPORTED WHEN THE CONTROL TOWER IS STAFFED. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 1 AM EST MONDAY FOR VAZ007-009. NC...NONE. WV...WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 1 AM EST MONDAY FOR WVZ042. && $$ SYNOPSIS...MBS NEAR TERM...MBS SHORT TERM...PM LONG TERM...DS AVIATION...KK/MBS/WP EQUIPMENT...RAB

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