Area Forecast Discussion
Issued by NWS Blacksburg, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KRNK 020037
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
737 PM EST SUN FEB 1 2015

.SYNOPSIS...
LOW PRESSURE CENTERED NEAR SPRINGFIELD ILLINOIS THIS EVENING WILL
MOVE EAST BE CENTERED NEAR PITTSBURGH BY DAYBREAK MONDAY BEFORE
MOVING OFF THE NEW ENGLAND COAST MONDAY AFTERNOON. A STRONG COLD
FRONT WILL TRAIL SOUTH FROM THE LOW...SWEEPING ACROSS THE OHIO AND
TENNESSEE VALLEYS TONIGHT...CROSSING THE APPALACHIANS MOUNTAINS
MONDAY MORNING. WIDESPREAD PRECIPITATION WILL ACCOMPANY THIS STORM
SYSTEM WITH SNOW NORTH OF INTERSTATE 70 AND RAIN TO THE SOUTH.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 730 PM EST SUNDAY...

CURRENTLY OBSERVING LIGHT RAIN ACROSS MUCH OF THE REGION THIS
EVENING...WITH SNOW FALLING ALONG THE HIGHER ELEVATIONS ALONG THE
INTERSTATE 64 CORRIDOR. FURTHER SOUTH...THERE ARE A FEW BRIGHT
SPOTS ON RADAR REFLECTIVITY...WHICH IS LIKELY INDICATING SLEET
MIXING WITH THE RAIN IN A FEW SPOTS. AT ANY RATE...PRECIPITATION
HAS ENTERED THE AREA MORE QUICKLY THAN EARLIER FORECAST...AND HAVE
THEREFORE INCREASED PRECIPITATION CHANCES FOR THE EVENING
AREAWIDE. THIS FIRST WAVE WILL PASS ACROSS OUR AREA...FOLLOWED BY
A BRIEF LULL...WITH MORE PRECIPITATION ENTERING BY LATE EVENING.
STILL LOOKING FOR PRECIPITATION AMOUNTS OVERNIGHT RANGING FROM A
HALF /0.50/ TO THREE-QUARTERS /0.75/ OF AN INCH. SNOWFALL
ACCUMULATIONS ACROSS HIGHEST PORTIONS OF WESTERN GREENBRIER COUNTY
AND PERHAPS BATH COUNTY COULD REACH CLOSE TO AN INCH.

AN AREA OF LOW PRESSURE OVER ILLINOIS WILL DEEPEN AS IT TRACKS
EAST-NORTHEAST OVERNIGHT...ENTERING WESTERN PENNSYLVANIA MONDAY
MORNING WITH THE ASSOCIATED COLD FRONT JUST ENTERING THE WESTERN
APPALACHIANS AROUND SUNRISE. BY EARLY AFTERNOON...THE COLD FRONT
IS ACROSS THE COASTAL PIEDMONT...WITH THE SURFACE LOW OFF THE NEW
JERSEY SHORE. COLD AIR WILL BEGIN TO ENTER THE AREA IN THE MORNING
WITH HIGHER ELEVATIONS TRANSITIONING TO SNOW EARLY. BY THE TIME
THE COLDER AIR ARRIVES IN NORTHWEST FLOW...BULK OF THE MOISTURE IS
OUT OF THE AREA. WESTERN SLOPES COULD SEE 2-3 INCHES ACROSS
WESTERN GREENBRIER TO UP TO 2 INCHES ALONG WESTERN GRAYSON TO
WESTERN WATAUGA. HIGH PRESSURE MOVES OVER THE OHIO VALLEY QUICKLY
AND UPSLOPE SNOW SHOWERS MAY NOT LAST TO LONG INTO THE EVENING.

QUICK PRESSURE RISES BEHIND THE FRONT WILL BRING WINDY AND GUSTY
CONDITIONS TO THE AREA MONDAY INTO MONDAY EVENING. MODELS HAVE
BACKED OFF ON THE STRENGTH OF THE LOW LEVEL JET...THEREFORE WILL
ONLY CARRY AN ADVISORY FOR COUNTIES ALONG AND WEST OF THE BLUE RIDGE
TO INCLUDE THE SOUTHWESTERN VIRGINIA FOOTHILLS FOR GUST OF 40 TO 50
MPH. ALONG WITH THE STRONG NORTHWEST WINDS...TEMPERATURES WILL BE
FALLING...ESPECIALLY ACROSS THE MOUNTAINS THROUGH THE DAY MONDAY.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 315 PM EST SUNDAY...

500MB HEIGHTS RISE ON MONDAY NIGHT. ZONAL PATTERN ON TUESDAY WITH A
NORTHERN STREAM SHORT WAVE CROSSING THE OHIO VALLEY AND MID ATLANTIC
STATES. THE -5 TO -15 850 MB AIR THAT WAS OVER THE NORTHERN PLAINS
REACHES THE FORECAST AREA ON MONDAY NIGHT. 850MB TEMPERATURES
MODERATE TUESDAY AND TUESDAY NIGHT AND BY WEDNESDAY AREA AROUND
ZERO.

STARTING OFF MONDAY NIGHT WITH STRONG PRESSURE RISES. BUFKIT
FORECAST DOES NOT HAVE WIND GUSTS DROPPING BELOW 20 MPH UNTIL AFTER
MIDNIGHT ON MONDAY NIGHT. DEEP MOISTURE WILL BE WELL TO THE EAST ON
MONDAY NIGHT WITH REMAINING MOISTURE CONFINED TO BELOW 800MB.
UPSLOPE SNOW SHOWERS WILL BE ENDING DURING THE EVENING BUT THE
CLOUD COVER MAY LINGER THROUGH TUESDAY MORNING.

SURFACE HIGH PRESSURE MOVES IN TO THE FORECAST AREA ON TUESDAY THEN
OFFSHORE TUESDAY NIGHT. NOT MUCH SURFACE REFLECTION WITH THE SHORT
WAVE COMING THROUGH ON TUESDAY. ARCTIC COLD FRONT PASSES THROUGH
REGION ON WEDNESDAY NIGHT. LOW CLOUDS FILL IN BEHIND THE FRONT ON
WEDNESDAY NIGHT WITH AN INCREASING CHANCE OF UPSLOPE SNOW SHOWERS BY
THURSDAY MORNING WITH THE LOW LEVEL JET BECOMING STRONGER OUT OF THE
NORTHWEST.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 300 PM EST SUNDAY...

LATEST WEATHER FORECAST MODELS ARE IN SLIGHTLY BETTER AGREEMENT
CONCERNING DEVELOPMENT OF A COASTAL LOW ON THURSDAY...AND HOW IT
WILL AFFECT OUR WEATHER. EXPECT TO START THE DAY WITH A COLD FRONT
MAKING ITS WAY ACROSS THE PIEDMONT...WITH LIGHT UPSLOPE SNOW SHOWER
ACTIVITY ALONG THE WESTERN RIDGES...AND PERHAPS A FEW SNOW SHOWERS
ACROSS THE PIEDMONT IN THE VICINITY OF THE FRONT. PROGRESSING INTO
THE AFTERNOON...THE LOW WILL DRIFT NORTH...THOUGH FARTHER OFF THE
COAST THAN FORECAST MODELS WERE PREVIOUSLY CALLING FOR. WITH THE LOW
TRACKING FURTHER AWAY FROM OUR AREA...DO NOT SEE MOISTURE BEING
PUSHED AS FAR INLAND...AND THEREFORE EXPECT THE HIGHER PRECIPITATION
AMOUNTS TO BE CONFINED MORE TO THE COAST. MODELS AGREE THAT
ATMOSPHERIC TEMPERATURES ARE COLD ENOUGH THAT ANY PRECIPITATION WILL
REMAIN EXCLUSIVELY SNOW AS NORTHERLY WINDS DRAW SUB FREEZING AIR
FROM THE GREAT LAKES REGION.

RIGHT NOW...HAVE ONLY MODERATE CONFIDENCE IN THIS FORECAST. THE
WEATHER FORECAST MODELS HAVE HAD NOT ONLY SIGNIFICANT DIFFERENCES
WITH ONE ANOTHER CONCERNING THE TRACK AND THE IMPACTS OF THE
LOW...THEY HAVE ALSO BEEN FLIP FLOPPING FROM THEIR PREVIOUS RUNS AS
TO HOW THE LOW WILL BEHAVE. SO WILL STILL NOT HAZARD A GUESS AS TO
HOW MUCH SNOW WE CAN EXPECT...EXCEPT TO SAY THAT THE WORST CASE
SCENARIO PUTS ACCUMULATIONS AROUND THE LOW END OF ADVISORY CRITERIA.

WITH THE DEPARTURE OF THE LOW OUT TO SEA THURSDAY EVENING...HIGH
PRESSURE ACROSS THE SOUTHERN GREAT LAKES WILL BECOME OUR DOMINANT
WEATHER FEATURE. THE HIGH WILL SHIFT ACROSS OUR AREA ON THURSDAY
NIGHT AND FRIDAY...RESULTING IN TEMPERATURES IN THE TEENS AND SINGLE
DIGITS TO START THE DAY. THE HIGH WILL THEN SETTLE ALONG THE
ATLANTIC COAST FRIDAY NIGHT INTO SATURDAY...ALLOWING SOUTHWESTERLY
WINDS TO TAKE OVER FOR OUR AREA. THIS WILL RESULT IN A GRADUAL
WARMUP FOR THE WEEKEND...AHEAD OF OUR NEXT COLD FRONT APPROACHING
FROM THE NORTH.

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
AS OF 645 PM EST SUNDAY...

POOR AVIATION CONDITIONS EXPECTED THROUGH THE TAF VALID
PERIOD...EXCEPT IMPROVING EAST OF THE BLUE RIDGE AFT 18Z MON.

SOUTHERN STREAM SYSTEM WILL TRACK ACROSS THE REGION TONIGHT/EARLY
MONDAY. THE SFC LOW WILL TRACK GENERALLY ALONG THE OH RIVER TOWARD
PIT...THEN TOWARD THE NORTHERN MID-ATLANTIC REGION MON. DEEP LOW
PRESSURE WILL DEVELOP OFF THE NORTHERN MID-ATLANTIC COAST MON
AFTERNOON. THIS WILL KEEP THE CWA SOLIDLY IN THE WARM SECTOR UNTIL
THE ASSOCIATED COLD FRONT ARRIVES EARLY MON IN THE WEST...REACHING
THE PIEDMONT MID-MORNING MON. EXPECT WIDESPREAD -RA ALL TAF
SITES THROUGH 08Z...WITH THE HEAVIEST MOVING THROUGH THE REGION IN
THE 04Z-08Z TIME FRAME FROM WEST TO EAST. WHILE THERE IS INITIALLY
A HEALTHY T/TD SPREAD...THE LOWER ATMOSPHERE WILL QUICKLY SATURATE
AS RAIN DEVELOPS. THIS WILL ALLOW CIGS AND VSBYS TO DROP FAIRLY
QUICKLY INTO THE MVFR CATEGORY. AT TIMES DURING THE HEAVIER
RAIN...WE WILL SEE IFR CIGS...WHICH COULD THEN PERSIST UNTIL THE
COLD FRONT ARRIVES EARLY TO MID-MORNING MON. AFTER THE COLD FRONT
PASSES...RAIN WILL MIX WITH AND CHANGE TO SNOW WEST OF THE BLUE
RIDGE...BUT END EAST OF THE BLUE RIDGE. INTENSE COLD ADVECTION AND
IMPROVING UPSLOPE WILL RESULT IN OCCASIONAL MODERATE -SHSN FOR A
PERIOD IN FAVORED UPSLOPE AREAS. CIGS WILL IMPROVE TO VFR BY EARLY
AFTERNOON EAST OF THE BLUE RIDGE...BUT WEST OF THE BLUE RIDGE...
AND ESPECIALLY ACROSS THE UPSLOPE AREAS OF THE ALLEGHANYS IFR-MVFR
CIGS AND MVFR VSBYS WILL PERSIST IN -SHSN UNTIL MID OR LATE
AFTERNOON. OTHERWISE...AS WITH THE PAST SEVERAL SYSTEMS...WIND
WILL BE A BIG CONCERN WITH THIS SYSTEM AS WELL. IN ADVANCE OF THE
FRONT...EXPECT SSE-SSW WINDS AT SPEEDS OF 7-10KTS WITH LOW END
GUSTS AT BLF/BCB/ROA. BEHIND THE FRONT...WINDS WILL BECOME W-WNW
15-25KTS WITH GUSTS 30-35KTS AND PERSIST INTO THE LATE AFTERNOON
BEFORE DIMINISHING AROUND SUNSET MONDAY.

MEDIUM CONFIDENCE IN CIGS AND VSBYS THROUGH THE TAF VALID PERIOD.
MEDIUM TO HIGH CONFIDENCE IN WIND DIR/SPD THROUGH THE TAF VALID
PERIOD.

EXTENDED DISCUSSION... MONDAY NIGHT...SKIES CLEAR AND WINDS
DIMINISH...RETURN TO VFR.

TUESDAY AND WEDNESDAY...HIGH PRESSURE PASSES OVERHEAD WITH VFR.

THURSDAY...LOW PRESSURE MOVING ACROSS THE SOUTHEAST U.S. MAY
BRING SUB-VFR CONDITIONS AND PRECIPITATION...POSSIBLY SNOW TO THE
REGION. SINCE THIS STORM IS TAKING A GULF COAST TRACK...WINTRY
PRECIPITATION MAY IMPACT SOUTHERN TERMINAL ROUTES INCLUDING
CHARLOTTE AND ATLANTA.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WIND ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT EST MONDAY
     NIGHT FOR VAZ009>020-022>024-032>035.
NC...WIND ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT EST MONDAY
     NIGHT FOR NCZ001-002-018.
WV...NONE.

&&

$$
SYNOPSIS...RCS
NEAR TERM...NF/RCS
SHORT TERM...AMS
LONG TERM...NF
AVIATION...RAB/RCS



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.