Area Forecast Discussion
Issued by NWS Sterling, VA

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720
FXUS61 KLWX 060217
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
917 PM EST FRI FEB 5 2016

.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVERHEAD THROUGH SATURDAY.
COASTAL LOW PRESSURE WILL PASS BY WELL TO THE SOUTH AND EAST
SUNDAY. ANOTHER LOW PRESSURE SYSTEM MAY IMPACT THE AREA MONDAY
INTO TUESDAY. THE LOW WILL MOVE AWAY FROM THE AREA DURING THE
MIDDLE PORTION OF NEXT WEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
HIGH PRESSURE IS BUILDING INTO THE MID-ATLANTIC FROM THE OHIO
VALLEY TONIGHT. WINDS HAVE RAPIDLY DIMINISHED THIS
EVENING...ALREADY BECOMING CALM IN MANY LOCATIONS. THIS HAS
ALLOWED TEMPERATURES TO QUICKLY TUMBLE...ALREADY NEARING FORECAST
LOWS IN SOME OF THE TYPICAL COLD SPOTS. MID-EVENING UPDATE WILL
DROP LOW TEMPERATURES BY AT LEAST A DEGREE OR TWO IN MOST
LOCATIONS OUTSIDE OF THE URBAN CENTERS. THE ONLY OTHER ISSUE FOR
THE NIGHT IS INCREASING CIRRUS ASSOCIATED WITH THE SOUTHERN STREAM
JET.

HIGH PRESSURE WILL REMAIN OVERHEAD SATURDAY. WINDS WILL BECOME LIGHT
AND SOUTHERLY WITH TEMPS REACHING THE MID 40S UNDER PARTLY TO MOSTLY
SUNNY CONDITIONS.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
AN UPPER LEVEL TROUGH WILL DIG INTO THE SE US SATURDAY NIGHT AND
SUNDAY. COASTAL LOW PRESSURE IS EXPECTED TO DEVELOP OFF THE
CAROLINA COAST BY SUNDAY MORNING. ACROSS THE MID-ATLANTIC... HIGH
PRESSURE PERSISTS OVERHEAD. CLOUDS WILL INCREASE SATURDAY NIGHT.
MOST OF THE MODEL GUIDANCE HAS THE UPPER LEVEL TROUGH PUSHING THE
COASTAL LOW OUT TO SEA AND THE MID-ATLANTIC WILL LIKELY NOT BE
IMPACTED SUNDAY. CONFIDENCE IS MEDIUM THAT PRECIPITATION WILL STAY
SOUTH OF THE REGION SUNDAY.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
A LARGE AREA OF LOW PRESSURE IN THE UPPER LEVELS SHOULD SPAWN A LOW
PRESSURE SYSTEM AT THE SURFACE IN THE MID-ATLANTIC REGION OR
CAROLINAS LATE MONDAY INTO MONDAY NIGHT. THIS NEWLY FORMED LOW COULD
HAVE A MORE DIRECT IMPACT TO OUR REGION...BRINGING LIGHT TO MODERATE
SNOW MONDAY NIGHT WITH COLDER AIR TO SUPPORT THE NEW LOW. A FEW
INCHES OF SNOW CANNOT BE RULED OUT.

ONE SIMILARITY WITH THE EUROPEAN MODEL AND THE GFS MODEL WITH THIS
NEW LOW IS BOTH CLOSE OFF THE NEW LOW NEAR THE MID-ATLANTIC COAST
TUESDAY BEFORE PIVOTING IT NORTHWARD TOWARD NEW ENGLAND TUESDAY
NIGHT.

THE DIFFERENCE IN THE POSITION OF THIS CLOSED LOW WILL DETERMINE
WHETHER THE MID-ATLANTIC REGION GETS HIT WITH MODERATE SNOW
ACCUMULATIONS OR A MIX OF RAIN AND SNOW SHOWERS WILL LITTLE SNOW
ACCUMULATION. AT THIS TIME...THE EUROPEAN MODEL CLOSES THE LOW
NEAR THE MOUTH OF THE CHESAPEAKE BAY. THE GFS MODEL CLOSES THE
LOW NEAR THE MOUTH OF THE DELAWARE BAY...FARTHER NORTH. WE
HAVE A CHANCE OF RAIN OR SNOW IN OUR REGION TUESDAY THEN A CHANCE OF
SNOW SHOWERS TUESDAY NIGHT.

THE MAIN UPPER LEVEL SUPPORT BEHIND THE COASTAL LOW WILL SLOWLY
PIVOT FROM THE OHIO VALLEY...ACROSS THE REGION...AND OFFSHORE
WEDNESDAY AND WEDNESDAY NIGHT. SOME UPSLOPE SNOW SHOWERS MAY EXIST
IN THE POTOMAC HIGHLANDS WITH COLDER AIR ALOFT PUNCHING INTO THE
REGION. A LINGERING SNOW SHOWER MAY BE NEAR THE CHESAPEAKE BAY AS
WELL. ELSEWHERE...COLDER AND DRIER AIR WILL FILTER INTO THE REGION
AS HIGH PRESSURE BUILDS IN FROM THE WEST.

HIGH PRESSURE SHOULD DOMINATE THURSDAY WITH CHILLY AND DRY AIR.
THE GFS IS A LITTLE MORE PRONOUNCED WITH AN UPPER LEVEL
DISTURBANCE LATE THURSDAY AND THURSDAY NIGHT THAN THE EUROPEAN. AT
BEST...THERE COULD BE A FEW SNOW SHOWERS IN PARTS OF THE REGION. THE
CONFIDENCE IS LOW.

AS FOR FRIDAY...CONFIDENCE REMAINS LOW ON THE WEATHER SINCE THE
EUROPEAN MODEL TAKES A STORM SYSTEM ALONG THE OHIO VALLEY INTO THE
MID-ATLANTIC REGION WHILE THE GFS MODEL HAS HIGH PRESSURE BEING THE
DOMINANT FEATURE.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE BUILDS TONIGHT...VFR EXPECTED. NW WINDS HAVE
DIMINISHED AND SHOULD GENERALLY BE 6 KT OR LESS THROUGH THE NIGHT.

HIGH PRESSURE REMAINS IN PLACE SATURDAY THROUGH SUNDAY. VFR
CONDITIONS EXPECTED. LIGHT SOUTHERLY FLOW SATURDAY...BECOMING
LIGHT NORTHERLY FLOW SUNDAY AS LOW PRESSURE MOVES OFFSHORE (AND
SHOULD HAVE LITTLE IMPACT).

IFR OR LIFR CONDITIONS MONDAY NIGHT WITH PERIODS OF LIGHT TO
MODERATE SNOW. WINDS EAST BECOMING NORTHEAST AROUND 5 KNOTS.

MVFR TO BRIEFLY IFR CONDITIONS TUESDAY WITH A CHANCE OF LIGHT RAIN
OR LIGHT SNOW. WINDS BECOMING NORTHWEST 5 TO 10 KNOTS.

&&

.MARINE...
HIGH PRESSURE BUILDS TONIGHT AND WINDS WILL CONTINUE TO DIMINISH.
WILL GO AHEAD AND DROP SCA...AS WINDS ARE NOW GENERALLY BELOW 15
KT...AND BELOW 10 KT IN MANY LOCATIONS.

HIGH PRESSURE REMAINS IN PLACE SATURDAY AND SUNDAY. LIGHT NW FLOW
WILL BECOME S ON SATURDAY...THEN SWING AROUND TO THE N OR NE ON
SUNDAY. WINDS WILL LIKELY INCREASE SUNDAY NIGHT AS A COASTAL LOW
DEVELOPS SOUTH OF THE WATERS.

SMALL CRAFT CONDITIONS ARE POSSIBLE MONDAY INTO TUESDAY DEPENDING
ON THE STRENGTH OF DEVELOPING LOW PRESSURE.

&&

.HYDROLOGY...
RIVER LEVELS CONTINUE TO DROP. THE POTOMAC RIVER AT EDWARDS
FERRY IS SHOULD FALL BELOW FLOOD STAGE IN THE NEXT SEVERAL HOURS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...HAS
NEAR TERM...ADS/HAS
SHORT TERM...HAS
LONG TERM...KLW
AVIATION...ADS/HAS/KLW
MARINE...ADS/HAS/KLW
HYDROLOGY...ADS



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