December 10, 2013: Forecast for Rain to Snow

It looks like another small system will being pushing through Central Virginia tomorrow morning into the early afternoon hours. The NWS has the following information:

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
QUICK UPDATE TO ACCOUNT FOR SHRAS ALONG THE FRONTAL BAND, WHICH HAVE
GENERALLY DIMINISHED...LEAVING ONLY SOME PATCHY LIGHT RAIN/DZ
ACROSS SE TIER OF COUNTIES. MEANWHILE, SOME MID/UPPER DRYING HAS
ENTERED EASTERN WV/WESTERN VA HAS ALLOWED FOR SOME AREAS OF FOG
OVER THE PIEDMONT...PRIMARILY WHERE CAD WEDGE WAS STRONGEST OVER
THE WEEKEND.

DID SLOW ONSET OF POP SLIGHTLY ACROSS OUR MD ZONES. OVERALL,
MUCH OF PREVIOUS FORECAST REMAINS UNCHANGED. LATER TONIGHT...A
VIGOROUS TROUGH (PRESENTLY DIVING SE ACROSS THE NORTHERN PLAINS)
WILL REACH THE MIDWEST. THIS WILL ALLOW -RA TO RE-DEVELOP ALONG
THE MOIST FRONTAL BAND AS IT LIFTS BACK NORTHWARD. ACCORDINGLY, WL
SHOW INCREASE IN POP LATE ACROSS MOST OF THE AREA (ASIDE FROM THE
LOWER MD EASTERN SHORE) LATER TONIGHT. TEMPERATURES SHOULD REMAIN
STEADY IN THE MID/UPPER 40S SE OVERNIGHT...WHILE LOWS SHOULD REACH
THE LOW/MID 30S NW WITH SHORT LIVED CLEARING.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
THE AFOREMENTIONED TROUGH GENERATES A POWERFUL 180KT (GEOSTROPHIC
WIND) 300MB JET...THAT RACES ENE ACROSS THE OHIO VALLEY TUESDAY
MORNING. THIS INDUCES A BAND OF STRONG FRONTOGENESIS ACROSS THE MID
ATLANTIC TUESDAY MORNING ALONG WITH ROBUST UPWARD VERTICAL MOTION.
ADDITIONALLY...THERE IS DECENT MOISTURE ADVECTION AHEAD OF THE
TROUGH. MODEL CROSS-SECTIONS (NAM/GFS) INDICATE A RATHER CLASSIC
SLOPING FRONTAL ZONE WITH STRONG FRONTOGENESIS FROM THE SURFACE TO
AROUND 600MB. IN ADDITION...MODESTLY NEGATIVE EPV VALUES AND
NEUTRAL THETA-E LAPSE RATES INDICATE A POTENTIAL FOR SYMMETRIC
INSTABILITY. ALL THIS COMBINED SUPPORTS THE POTENTIAL FOR HEAVY
BANDED PRECIPITATION ACROSS THE MID-ATLANTIC REGION.

AT THIS TIME...THE STRONGEST BAND APPEARS TO SET-UP NEAR THE FAR
NORTHERN PORTION OF THE AKQ CWA. GIVEN THE STRENGTH OF THE
SYSTEM...THERE SHOULD BE LITTLE DIFFICULTY CHANGING THE PRECIP OVER
TO SNOW (DRIVING SURFACE TEMPS DOWN TO THE WET-BULB...WHICH WL BE
~ 30-32F)...BUT THERE COULD BE A MIX WITH SLEET EARLY DUE TO
RESIDUAL MID-LEVEL WARM AIR. SNOW AMOUNTS SHOULD RANGE FROM 1-3IN
ACROSS THE FAR N (LOCALIZED AMOUNTS AROUND 4 ARE POSSIBLE)...AND
TAPERING TO AN INCH OR LESS IN VICINITY OF A LINE FROM FVX-RIC-
WAL. AN ADVISORY HAS BEEN RAISED FOR THE NORTHERN PORTION OF THE
AREA.

DRIER AIR QUICKLY COMES IN FROM THE WEST DURING THE AFTERNOON AND
THIS SHOULD BRING A QUICK END TO PRECIPITATION. HIGH PRESSURE
FINALLY BUILDS IN FROM THE NW TUESDAY NIGHT INTO THURSDAY BRINGING
DRIER BUT VERY COLD CONDITIONS. LOWS TUESDAY/WEDNESDAY NIGHT SHOULD
RANGE FROM THE UPPER TEENS TO LOW 20S NW...TO THE LOW 30S NC
COAST...WITH HIGHS WEDNESDAY/THURSDAY ONLY IN THE UPPER 30S TO LOWER
40S FOR MOST AREAS.

 

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE WAKEFIELD VA
350 PM EST MON DEC 9 2013

VAZ060-061-067>071-078-082-083-085-099-102100-
PRINCE EDWARD-CUMBERLAND-NOTTOWAY-AMELIA-POWHATAN-CHESTERFIELD-
HENRICO-LANCASTER-CHARLES CITY-NEW KENT-MIDDLESEX-ACCOMACK-
350 PM EST MON DEC 9 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL VIRGINIA...EAST
CENTRAL VIRGINIA...SOUTH CENTRAL VIRGINIA...THE EASTERN SHORE OF
VIRGINIA...THE MIDDLE PENINSULA OF VIRGINIA...THE NORTHERN NECK OF
VIRGINIA AND THE PIEDMONT OF CENTRAL VIRGINIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

NO HAZARDOUS WEATHER EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

RAIN WILL TRANSITION TO A MIX OF SNOW AND SLEET LATER TUESDAY
MORNING...BEFORE BECOMING ALL SNOW EARLY IN THE AFTERNOON. AN INCH
OR LESS OF SNOW ACCUMULATION IS EXPECTED...MAINLY ON ELEVATED AND
NON-PAVED SURFACES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

 

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