Winter Weather in Virginia, January 11 to 12, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
334 PM EST SUN JAN 11 2015

.SYNOPSIS...
ARCTIC HIGH PRESSURE WILL SHIFT OFF THE EAST COAST TONIGHT. A WEAK COLD
FRONT WILL CROSS THE AREA ON MONDAY. HIGH PRESSURE WILL BUILD NORTH
THROUGH MIDWEEK BEFORE LOW PRESSURE MOVES OFF THE CAROLINA COAST
THURSDAY NIGHT. HIGH PRESSURE THEN PREVAILS INTO NEXT WEEKEND.

&&

.NEAR TERM /THROUGH MONDAY/...
CLOUDS CONTINUE TO INCREASE THIS AFTERNOON AND EVENING AHEAD OF
APPROACHING SOUTHERN STREAM STORM SYSTEM. TEMPERATURES ABOVE
FREEZING IN MOST LOCATIONS AND MAY BE SLOW TO FALL EARLY THIS
EVENING.

THE PRIMARY CONCERN OF THE SHORT TERM FORECAST IS THE POTENTIAL FOR
A LIGHT ICING EVENT ACROSS MOST IF NOT THE ENTIRE AREA LATE TONIGHT
AND EARLY MONDAY MORNING. THE ONE CRITICAL ELEMENT OF THE FORECAST
WILL BE THE SFC TEMPERATURES. NOT MUCH CHANGE IN THE THERMAL PROFILE
ALOFT...AS A WARM NOSE GREATER THAN 3C WILL BE IN PLACE ACROSS MOST
OF THE AREA BY THE TIME PRECIP STARTS. SOME SLEET MAY MIX IN AT THE
ONSET ACROSS THE NORTHERN THIRD OF THE AREA BUT THIS SHOULD BE SHORT
LIVED. ADMITTEDLY IT IS DISCONCERTING TO SEE THE SPREAD IN SFC TEMPS
AND THE MODELS TRYING TO HANG ON TO ABOVE FREEZING AIR. THIS IS NOT
TOTALLY UNEXPECTED SINCE THE SFC HIGH OFF THE COAST WILL NOT SUPPORT
A CLASSIC CAD AND THERE WILL NOT BE COLD AIR REPLENISHMENT FROM THE
NORTHEAST. WE WILL HAVE TO RELY ON AN IN-SITU CAD EVENT/WET BULB
PROCESSES TO TAKE PLACE...AND THIS DOES SUPPORT TEMPS FALLING BELOW
FREEZING ACROSS MOST OF THE AREA FOR AT LEAST SEVERAL HOURS
OVERNIGHT. THE FIRST PLACES TO RISE ABOVE FREEZING (ASSUMING THEY
FALL BELOW) WILL BE THE HIGHER ELEVATIONS (THE WARM NOSE WILL WORK
DOWN TO THEM FIRST) AND THE COASTAL PLAIN (THE SOUTHERLY FLOW WILL
PREVENT TEMPERATURES FROM STAYING COLD). IN ADDITION TO A COLDER
START FROM THIS AFTERNOON...THE PRECIP-INDUCED COOLING WILL HAVE A
HARDER TIME SCOURING OUT OF NORTHERN MD...THE EASTERN WV
PANHANDLE...AND PERHAPS FAR NORTHERN VA. IN THIS AREA WE HAVE THE
HIGHEST CONFIDENCE OF ACCUMULATING ICE.

PRECIP START TIME IS SHOWING SOME VARIATION IN THE MODELS...WITH
RECENT HRRR AND RAP RUNS WELL AFTER MIDNIGHT. DIDN/T MAKE MUCH
CHANGE TO THE GOING FORECAST POPS AS THE MAJORITY OF THE MODELS
STILL WARRANT POPS INCREASING JUST PRIOR TO MIDNIGHT. HOWEVER
WIDESPREAD PRECIP MAY NOT START UNTIL AFTER 09Z.

ICE ACCUMULATIONS SHOULD BE LIGHT GIVEN THE TEMPERATURES NEAR
FREEZING BUT AS NOTED ABOVE...THE HIGHEST AMOUNTS ARE EXPECTED
CLOSER TO THE MD/PA BORDER. HAVE CAPPED THESE AROUND 0.1 INCH...BUT
A FEW HIGHER REPORTS ARE POSSIBLE. OTHER AREAS WILL PROBABLY BE
LESS...BUT TEMPS/PRECIP RATES WILL HAVE TO BE MONITORED. ANOTHER
ISSUE TO CONSIDER IS THE AMBIENT COLD GROUND AFTER THE RECENT COLD
SPELL. COULD SEE ACCRETION OCCUR EVEN WITH AIR TEMPS SLIGHTLY ABOVE
FREEZING. TYPICALLY SHADED SPOTS AND BRIDGES WOULD BE A GREATER
CONCERN FOR THE GROUND ACCUMULATIONS. IMPORTANTLY...FZRA WILL LIKELY
BE AFFECTING MUCH OF THE AREA DURING THE MORNING COMMUTE. THEREFORE
HAVE ISSUED A FREEZING RAIN ADVISORY FOR THE ENTIRE AREA. IT WILL
RUN THROUGH 9 AM FOR MOST OF THE AREA EXCEPT THE COLDER LOCATIONS
MENTIONED ABOVE WHERE IT WILL BE IN EFFECT UNTIL 1 PM. THESE TIMES
MAY BE A LITTLE LENGTHY FOR SOME LOCATIONS...BUT WANTED TO
INCORPORATE UNCERTAINTY AND UNEVEN DISTRIBUTION OF THE TEMPERATURE
CURVE.

THE PRECIP WILL BE ALL RAIN DURING THE AFTERNOON AND BEGIN TO TAPER
OFF FROM WEST TO EAST. A STRONGER LLJ WILL MEAN PLENTY OF FORCING
AND MOISTURE FOR A GENERALLY STEADY RAIN...IN ADDITION TO HELPING
ELIMINATE ANY INVERSION AND THE TEMPERATURES RISE. MID 40S WILL BE
POSSIBLE IN THE SOUTHERN PART OF THE AREA...WITH THE NORTH STUCK IN
THE MID 30S.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
ANOTHER SURGE OF ARCTIC AIR WILL POUR INTO THE MIDDLE ATLANTIC
REGION MONDAY NIGHT. TEMPERATURES WILL DROP INTO THE TEENS IN MOST
AREAS WITH LOWER 20S IN THE BALTIMORE AND WASHINGTON DC METRO.
COLD HIGH PRESSURE WILL BUILD IN FOR TUESDAY AND TEMPERATURES WILL
NOT RISE ALL THAT MUCH DESPITE SUNSHINE. HIGH TEMPERATURES WILL ONLY
REACH THE MIDDLE TO UPPER 20S IN MOST LOCATIONS...PERHAPS LOW 30S
OVER SOUTHERN PORTIONS OF THE AREA. DRIER AIR WILL ALSO FILSTER IN
WITH THE HIGH PRESSURE RIDGE. HAVE REMOVED POPS FOR ALL AREAS
DURING THE DAY. ANOTHER COLD NIGHT EXPECTED TUESDAY NIGHT WITH
LOWS IN THE TEENS.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE LONG TERM WILL BEGIN WITH THE MID-ATLANTIC IN A WEAK CAD
SITUATION DUE TO ELONGATED TROUGHING TO OUR NORTH...STRETCHING FROM
THE GREAT LAKES TO NEW ENGLAND...AND A BROAD AREA OF TROUGHING
LOCATED ALONG AND OFF THE SOUTHEAST COAST TO OUR SOUTH. WHILE MOST
OF THE PRECIPITATION ASSOCIATED WITH THE TROUGHING SHOULD STAY TO
OUR SOUTH THROUGH MIDWEEK...A WEAK SHORTWAVE CROSSING THE AREA DURING THE
DAYTIME WEDNESDAY WILL PROVIDE THE BEST CHANCE FOR PRECIP TO REACH
THE CWA. THUS CHANCE POPS MAINLY CONFINED TO THE SOUTHEASTERN SECTOR
OF THE CWA WEDNESDAY THROUGH THURSDAY. COLD AIR IN PLACE AT THE
SURFACE AND LACK OF STRONG WARM NOSE IN THE MID-LEVELS SHOULD ENSURE
THAT ANY PRECIP THAT DOES FALL WILL BE IN THE FORM OF SNOW...WITH
THE EXCEPTION OF THE FAR SOUTHERN PORTION OF THE CWA WHERE TEMPS
SHOULD BE WARM ENOUGH DURING THE DAYTIME THURSDAY TO PRODUCE PLAIN
RAIN. POPS CURRENTLY TOO LOW TO EXPECT ANY ACCUMULATION.

BROAD HIGH PRESSURE WILL BEGIN TO BUILD IN WEDNESDAY NIGHT BEFORE
ENCOMPASSING THE ENTIRE EASTERN CONUS BY FRIDAY NIGHT. UPPER LEVEL
RIDGING DURING THIS SAME TIME WILL LEAD TO PLENTY OF SUNSHINE AND
NEAR NORMAL TEMPS. WEAK SOUTHERLY FLOW WILL BEGIN TO DEVELOP AS THE
HIGH MOVES OFF THE COAST SATURDAY NIGHT AND SUNDAY WILL BRING ABOVE
NORMAL TEMPS IN LIGHT SOUTHERLY FLOW.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
CLOUDS WILL CONTINUE TO LOWER LATE THIS AFTERNOON AND EVENING AHEAD
OF AN APPROACHING LOW PRESSURE SYSTEM. PRECIP WILL BEGIN AROUND
MIDNIGHT...WITH IFR CONDITIONS GRADUALLY DEVELOPING BY DAYBREAK.
COULD BE LOWER AT TIMES. A PERIOD OF FZRA IS LIKELY AT THE
TERMINALS...BUT TEMPERATURES WILL BE VERY CLOSE TO FREEZING. IAD/MRB
HAVE THE GREATEST CHANCE AT A PROLONGED PERIOD OF ICING. THE THREAT
FOR ICING WILL DECREASE BETWEEN 12-15Z...WITH RAIN EXPECTED INTO THE
AFTERNOON AND CONTINUED IFR OR LOWER CONDITIONS. SOME IMPROVEMENT
POSSIBLE BY LATE AFTERNOON AS PRECIP TAPERS OFF. A COLD FRONT WILL
PASS THROUGH LATE IN THE DAY AND SHIFT LIGHT WINDS FROM S TO NW.

VFR CONDITIONS ARE EXPECTED TUESDAY INTO TUESDAY NIGHT. CONFIDENCE
IS LOW IN THE OCCURRENCE OF AVIATION HAZARDS THROUGH THE LONG TERM
PERIOD.

&&

.MARINE...
LIGHT SOUTHERLY WINDS WILL CONTINUE THROUGH TONIGHT AND MOST OF
MONDAY. AS A LOW PRESSURE SYSTEM APPROACHES THE WATER. PRECIPITATION
WILL MOVE IN LATE TONIGHT AND LAST THROUGH MONDAY. A PERIOD OF
FREEZING RAIN IS POSSIBLE...BUT A MAJORITY OF THE EVENT WILL BE
PLAIN RAIN ON THE WATERS. A COLD FRONT WILL MOVE THROUGH LATE IN THE
DAY AND SHIFT WINDS TO THE NW.

SMALL CRAFT CONDITIONS MAY BE POSSIBLE TUESDAY INTO TUESDAY NIGHT
ON ALL WATERS. A SMALL CRAFT ADVISORY MAY ALSO BE NECESSARY INTO
THE DAY WEDNESDAY WITH BREEZY NORTHERLY WINDS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...FREEZING RAIN ADVISORY FROM 10 PM THIS EVENING TO 9 AM EST
     MONDAY FOR DCZ001.
MD...FREEZING RAIN ADVISORY FROM 10 PM THIS EVENING TO 9 AM EST
     MONDAY FOR MDZ011-013-014-016>018-504-506-508.
     FREEZING RAIN ADVISORY FROM 10 PM THIS EVENING TO 1 PM EST
     MONDAY FOR MDZ003>006-501>503-505-507.
VA...FREEZING RAIN ADVISORY FROM 10 PM THIS EVENING TO 9 AM EST
     MONDAY FOR VAZ025>031-036>040-050>057-501>504-506>508.
     FREEZING RAIN ADVISORY FROM 10 PM THIS EVENING TO 1 PM EST
     MONDAY FOR VAZ505.
WV...FREEZING RAIN ADVISORY FROM 10 PM THIS EVENING TO 9 AM EST
     MONDAY FOR WVZ050-055-501>506.
     FREEZING RAIN ADVISORY FROM 10 PM THIS EVENING TO 1 PM EST
     MONDAY FOR WVZ051>053.
MARINE...NONE.

&&

SYNOPSIS...KRW
NEAR TERM...ADS
SHORT TERM...KRW
LONG TERM...CEB
AVIATION...ADS/CEB/KRW
MARINE...ADS/CEB/KRW

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
342 PM EST SUN JAN 11 2015

ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-121045-
CHESAPEAKE BAY NORTH OF POOLES ISLAND MD-
CHESAPEAKE BAY FROM POOLES ISLAND TO SANDY POINT MD-
CHESAPEAKE BAY FROM SANDY POINT TO NORTH BEACH MD-
CHESAPEAKE BAY FROM NORTH BEACH TO DRUM POINT MD-
CHESAPEAKE BAY FROM DRUM POINT MD TO SMITH POINT VA-
TIDAL POTOMAC FROM KEY BRIDGE TO INDIAN HEAD MD-
TIDAL POTOMAC FROM INDIAN HEAD TO COBB ISLAND MD-
TIDAL POTOMAC FROM COBB ISLAND MD TO SMITH POINT VA-
PATAPSCO RIVER INCLUDING BALTIMORE HARBOR-
CHESTER RIVER TO QUEENSTOWN MD-EASTERN BAY-
CHOPTANK RIVER TO CAMBRIDGE MD AND THE LITTLE CHOPTANK RIVER-
PATUXENT RIVER TO BROOMES ISLAND MD-
TANGIER SOUND AND THE INLAND WATERS SURROUNDING BLOODSWORTH
ISLAND-DISTRICT OF COLUMBIA-SOUTHERN BALTIMORE-PRINCE GEORGES-
ANNE ARUNDEL-CHARLES-ST. MARYS-CALVERT-SOUTHEAST HARFORD-
PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX-
ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA-
KING GEORGE-
342 PM EST SUN JAN 11 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE MARYLAND PORTION OF THE
CHESAPEAKE BAY...TIDAL POTOMAC RIVER...AND ADJACENT COUNTIES IN
CENTRAL MARYLAND AND NORTHERN VIRGINIA AS WELL AS THE DISTRICT OF
COLUMBIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A FREEZING RAIN ADVISORY IS IN EFFECT BEGINNING LATE THIS
EVENING. LIGHT FREEZING RAIN IS EXPECTED WITH ICY CONDITIONS
POSSIBLE OVERNIGHT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

A FREEZING RAIN ADVISORY IS IN EFFECT INTO MONDAY MORNING. LIGHT
FREEZING RAIN WILL CHANGE TO PLAIN RAIN BY MID MORNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053-
055-501>506-121045-
WASHINGTON-FREDERICK MD-CARROLL-NORTHERN BALTIMORE-
EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-
NORTHWEST MONTGOMERY-CENTRAL AND SOUTHEASTERN MONTGOMERY-
NORTHWEST HOWARD-CENTRAL AND SOUTHEAST HOWARD-NORTHWEST HARFORD-
AUGUSTA-ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE-
NELSON-ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-ORANGE-CULPEPER-
NORTHERN FAUQUIER-SOUTHERN FAUQUIER-WESTERN HIGHLAND-
EASTERN HIGHLAND-WESTERN LOUDOUN-EASTERN LOUDOUN-
NORTHERN VA BLUE RIDGE-CENTRAL VA BLUE RIDGE-HAMPSHIRE-MORGAN-
BERKELEY-JEFFERSON-HARDY-WESTERN GRANT-EASTERN GRANT-
WESTERN MINERAL-EASTERN MINERAL-WESTERN PENDLETON-
EASTERN PENDLETON-
342 PM EST SUN JAN 11 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN WEST VIRGINIA...
NORTHERN AND CENTRAL VIRGINIA...AND CENTRAL AND WESTERN MARYLAND
WITH THE EXCEPTION OF GARRETT COUNTY.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A FREEZING RAIN ADVISORY IS IN EFFECT FOR THE ENTIRE AREA BEGINNING
LATE THIS EVENING. LIGHT FREEZING RAIN IS EXPECTED TO DEVELOP FROM
SOUTHWEST TO NORTHEAST WITH ICY CONDITIONS POSSIBLE OVERNIGHT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

A FREEZING RAIN ADVISORY IS IN EFFECT THROUGH MIDDAY MONDAY. LIGHT
FREEZING RAIN IS EXPECTED. THE FREEZING RAIN WILL GRADUALLY CHANGE
TO PLAIN RAIN BY EARLY AFTERNOON.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.