Area Forecast Discussion
Issued by NWS Blacksburg, VA

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638 FXUS61 KRNK 060953 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 453 AM EST SAT FEB 6 2016 .SYNOPSIS...
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HIGH PRESSURE WILL BE CENTERED OVER THE MID ATLANTIC REGION TODAY. A STORM SYSTEM DEVELOPING OFF THE SOUTHEAST COAST WILL MOVE NORTHEAST BUT PASS WELL TO THE SOUTH AND EAST OF THE AREA SUNDAY AND SUNDAY NIGHT. A SECOND AREA OF LOW PRESSURE WILL MOVE SOUTHEAST THROUGH THE UPPER MID WEST...CROSSING THE MOUNTAINS FROM THE NORTHWEST EARLY NEXT WEEK. THIS SECOND LOW WILL HAVE THE GREATEST IMPACT ON OUR WEATHER...BRINGING MUCH COLDER TEMPERATURES ALONG WITH SNOW SHOWERS FOR MONDAY THROUGH WEDNESDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 430 AM EST SATURDAY... SOME HIGH THIN CLOUDS OVERSPREAD THE AREA LAST NIGHT...REMAINING VERY THIN FOR MOST OF THE NIGHT AND ALLOWING TEMPERATURES TO DIP INTO THE TEENS TO LOWER 20S. AFTER A COLD START THIS MORNING EXPECTING A REBOUND BACK ABOVE FREEZING. QUESTION IS WHETHER WE WILL BE AS WARM AS MOS WHICH IS ADVERTISING HIGHS IN THE MID TO UPPER 40S. THIS WILL LIKELY DEPEND ON THE THICKNESS OF THE HIGH CLOUDS TODAY...MODELS SUGGESTING AT LEAST 50 PERCENT OPAQUE WHICH WILL LIMIT FULL INSOLATION. ATTM HAVE TRIMMED HIGHS A DEGREE OR TWO COMPARED TO MAV MOS...BUT DID NOT STRAY TOO MUCH PER POTENTIAL FOR CLOUDS TO BE THINNER THAN FORECAST. WEATHER MAP SHOWS A 1031 MB SURFACE HIGH CENTERED OVERHEAD. THE BOUNDARY LAYER IS VERY DRY WITH DEWPOINTS IN THE TEENS. THE CLOUDS ARE ASSOCIATED WITH UPPER LEVEL MOISTURE WHICH IS STREAMING AHEAD OF AN APPROACHING UPPER LEVEL TROUGH IN THE CENTRAL CONUS. SHORTWAVE ENERGY WHICH IS PASSING THROUGH THE BASE OF THE TROUGH IS BEGINNING TO CUT OFF FROM THE MAIN FLOW...THUS RESULTING IN A SWIRL OF PRECIP OVER EASTERN TX. THIS UPPER LEVEL FEATURE IS PROGGED TO DRIFT EAST ALONG THE GULF COAST TODAY AND TONIGHT. AS THE TROUGH MOVES EAST...AN AREA OF SURFACE LOW PRESSURE WILL DEVELOP JUST OFF THE COAST VCNTY OF JACKSONVILLE FLORIDA...THEN BEGIN TO DEEPEN AND TRACK NORTHEAST ALONG THE GULF STREAM. MODELS KEEP DEEPEST MOISTURE CONFINED TO THE SOUTHEAST ATLANTIC COAST...WITH POTENTIAL TO REACH AS FAR INLAND AS THE COLUMBIA SC TO RALEIGH DURHAM CORRIDOR LATE TONIGHT. FARTHER NORTHWEST OVER OUR FORECAST AREA THE THREAT FOR PRECIPITATION IS SMALL ENOUGH NOT TO INCLUDE IN THE FORECAST ATTM. IN THE EVENT THE STORM WERE TO TRACK CLOSER TO THE COAST THEN CHANGES WOULD BE NEEDED TO INTRODUCE A CHANCE OF PRECIP EARLY SUNDAY MORNING FOR AREAS JUST SOUTHEAST OF DANVILLE. FOR NOW...MODEL CONSENSUS IS TO KEEP THE PRECIP THREAT OUT OF OUR CWA...THEREFORE WILL CONTINUE TO ENTERTAIN A DRY FORECAST. THAT BEING SAID... THE ONLY SENSIBLE WEATHER WE WILL LIKELY SEE OVER THE NEXT 24 HOURS WILL BE CLOUD COVER WHICH WILL BE IN THE FORM OF THE UPPER LEVEL CIRRUS...THICKENING FOR A PERIOD OF TIME TODAY AND TONIGHT...AND LINGERING ACROSS OUR SOUTHEASTERN CWA SUNDAY. THIS WILL PRIMARILY IMPACT TEMPERATURE...KEEPING US UNDER GUIDANCE TODAY...AND POTENTIALLY KEEPING US ABOVE GUIDANCE TONIGHT.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
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AS OF 430 AM EST SATURDAY... UPPER LEVEL LOW CLOSES OFF OVER THE UPPER MISSISSIPPI VALLEY ON SUNDAY MORNING...DIGS SOUTHWARD INTO THE OHIO VALLEY SUNDAY AFTERNOON INTO SUNDAY NIGHT...THEN ROTATES EASTWARD MONDAY. THE SOUTHERN STREAM SYSTEM GETS KICKED TO THE EAST THEN NORTHEAST INTO MONDAY. AT THE SURFACE...THE COASTAL LOW PRESSURE OFF THE GEORGIA COAST SUNDAY MORNING WILL DEEPEN AS IT MOVES NORTHWARD SUNDAY AND NORTHEAST OFF INTO THE ATLANTIC OCEAN SUNDAY NIGHT INTO MONDAY. MEANWHILE...LOW PRESSURE MOVES EASTWARD THROUGH THE GREAT LAKES INTO MONDAY WITH A SECONDARY LOW DEVELOPING OVER THE MID ATLANTIC REGION...WHICH THEN DEEPENS OFF THE COAST ON TUESDAY. THE RICHER MORE WIDESPREAD CLOUD COVER SUNDAY WILL OCCUR IN THE EAST CLOSER TO THE COASTAL LOW CENTER LIFTING NORTHEAST ALONG THE EAST COAST. HIGH TEMPERATURES ON SUNDAY WILL RANGE FROM THE LOWER 40S IN THE MOUNTAINS TO THE LOWER 50S IN THE PIEDMONT. CLOUDS INCREASE FROM THE WEST AHEAD OF THE NORTHERN STREAM SYSTEM SUNDAY NIGHT. THE GFS IS FASTER WITH BRINGING THE DEEPER MOISTURE IN THE WEST SUNDAY NIGHT INTO MONDAY COMPARED TO NAM AND ECMWF. WITH THE DRY AIRMASS IN PLACE LEANED TOWARDS SLOWER SOLUTION...ALLOWING SOME LIGHT POPS FOR SNOW IN THE WEST LATE SUNDAY NIGHT. LOW TEMPERATURES SUNDAY NIGHT WILL VARY FROM THE LOWER 20S IN THE MOUNTAINS TO THE LOWER 30SALONG THE SOUTHERN BLUE RIDGE. MOISTURE SPREADS QUICKLY EAST ON MONDAY WITH A REGION OF GOOD UPPER DIFFLUENCE CROSSING THE MID ATLANTIC REGION. A MIXTURE OF RAIN AND SNOW IS EXPECTED ON MONDAY. HIGH TEMPERATURES MONDAY WILL RANGE FROM AROUND 30 DEGREES IN THE MOUNTAINS TO NEAR 50 DEGREES IN THE PIEDMONT. IT BECOMES COLD ENOUGH FOR ALL AREAS TO CHANGEOVER TO SNOW MONDAY NIGHT. LOW TEMPERATURES MONDAY NIGHT WILL GENERALLY BE IN THE 20S. SNOW ACCUMULATIONS FOR MONDAY AND MONDAY NIGHT WILL VARY FROM A COATING IN THE EAST TO AS MUCH AS 5 INCHES IN NORTHWEST UPSLOPE LOCATIONS IN GREENBRIER COUNTY IN WEST VIRGINIA. THIS MATCHES UP FAIRLY WELL WITH WPC DAY 3 SNOW ACCUMULATIONS ENDING 12Z TUESDAY. WILL THE THE MENTION OF THE POTENTIAL FOR SNOW TO THE HWO. THE COMBINATION OF TEMPERATURES AND WINDS WILL CREATE WIND CHILLS AS COLD AS THE SINGLE DIGITS.
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&& .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 250 PM EST FRIDAY... SIGNIFICANT LOWERING OF HEIGHTS AND TEMPERATURES BY TUESDAY...WITH EASTERN 500 MB LONG WAVE TROF BEING RE-ENFORCED BY ANOTHER SHORT WAVE ON WEDNESDAY. THE TROF AXIS MOVES EAST...HEIGHTS RISE...AND TEMPERATURES MODERATE WEDNESDAY NIGHT AND THURSDAY. EXPECTING LONG FETCH OF NORTHWEST FLOW...THAT MAY EVEN TAP MOISTURE FROM THE ONLY PARTIALLY FROZEN GREAT LAKES TUESDAY NIGHT AND WEDNESDAY. QUESTIONABLE IF THE WESTERN UPSLOPE WILL CONTINUE PAST WEDNESDAY NIGHT SINCE SURFACE TO 850 MB WINDS BECOME MORE WEST BY THAT TIME. COLD 850 MB AIR WITH THE EASTERN TROF REACHES THE FORECAST AREA ON TUESDAY NIGHT AND WEDNESDAY...POTENTIALLY BOTTOMING OUT AROUND -18 BY WEDNESDAY NIGHT. WILL HIGHLIGHT POTENTIAL LOW WIND CHILL VALUES AT HIGHER ELEVATIONS IN THE FAR WESTERN COUNTY WARNING AREA IN THE HAZARDOUS WEATHER OUTLOOK. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... AS OF 1150 PM EST FRIDAY... VFR CONDITIONS EXPECTED THROUGH THE TAF VALID PERIOD WITH A VERY DRY AIR MASS AND WEAK HIGH PRESSURE ACROSS THE REGION THROUGH THE TAF VALID PERIOD. AN UPPER LOW TRACKING THROUGH THE SOUTHERN STATES WILL SPREAD INCREASING CIRRUS THROUGH THE REGION FROM THE WEST AND SOUTHWEST THROUGH THE PERIOD. CIGS WILL REMAIN AT OR ABOVE 150 THROUGH THE TAF VALID PERIOD. NO RESTRICTIONS TO VISIBILITY ARE EXPECTED. WINDS WILL BE CHAOTIC AND LIGHT...TRENDING TOWARD MOSTLY CALM AT NIGHT AND VARIABLE 3-6KTS DURING THE DAYLIGHT HOURS. IF ANY TENDENCY IN THE DIRECTION CAN BE ASCERTAINED...IT WOULD BE TOWARD THE SW-WSW. HIGH CONFIDENCE IN VFR CIGS AND VSBYS THROUGH THE TAF VALID PERIOD. MEDIUM CONFIDENCE IN WIND DIRECTION THROUGH THE TAF VALID PERIOD. HIGH CONFIDENCE IN WIND SPEED THROUGH THE TAF VALID PERIOD. EXTENDED DISCUSSION... VFR CONDITIONS WILL CONTINUE INTO SUNDAY AS AN UPPER LOW REMAINS WELL SOUTHEAST OF THE REGION. AS WE MOVE INTO NEXT WEEK...A STRONG UPPER AREA OF LOW PRESSURE WILL SINK SOUTHWARD FROM THE GREAT LAKES BY MONDAY LEADING TO OVERALL MVFR CONDITIONS ACROSS MOST TAF SITES. AN ASSOCIATED COLD FRONT PASSES THROUGH MONDAY NIGHT FOLLOWED BY A SECONDARY ARCTIC BOUNDARY TUESDAY EVENING. THESE SHOULD COMBINE TO KEEP SUB-VFR OVER THE MOUNTAINS WITH LOWER CEILINGS CONTINUING WITH THE PRESENCE OF SNOW SHOWERS MONDAY NIGHT...CONTINUING THROUGH WEDNESDAY AS A STRONG UPSLOPE FLOW PATTERN KICKS IN. A MIX OF MVFR/VFR EXPECTED AT TIMES IN THE EAST WITH DOWNSLOPE LIMITING CLOUD COVER FOR TUESDAY INTO WEDNESDAY. SOME ALBERTA CLIPPERS WILL BE TRACKING THROUGH THE BASE OF THE UPPER TROUGH...WHICH COULD BRING SNOW SHOWERS AND LIGHT SNOW TO AREAS FURTHER EAST OF THE ALLEGHANYS AT TIMES. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PM NEAR TERM...PM SHORT TERM...KK LONG TERM...AMS AVIATION...JH/JM/RAB

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