Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 130901
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
401 AM EST SAT FEB 13 2016

.SYNOPSIS...ARCTIC HIGH PRESSURE WILL BUILD THROUGH EARLY SUNDAY
THEN MOVE OFFSHORE SUNDAY NIGHT. LOW PRESSURE WILL MOVE ACROSS THE
AREA TUESDAY. HIGH PRESSURE RETURNS FOR MIDDLE TO LATTER PART OF
NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/... A STRONG COLD FRONT IS MOVING THROUGH
THE MID-ATLANTIC REGION THIS MORNING. SCATTERED TO NUMEROUS SNOW
SHOWERS ARE PRODUCING HEAVY SNOW AND LOW VISIBILITIES. THESE SNOW
SHOWERS WILL CONTINUE TO IMPACT PORTIONS OF THE
BALTIMORE/WASHINGTON DC METROS THROUGH SUNRISE. A QUICK INCH OF
SNOW IS EXPECTED WITHIN THE HEAVIEST SNOW SHOWERS.

POST-FRONTAL CONDITIONS EXPECTED TODAY WITH GUSTY WINDS AND COOLER
TEMPERATURES. WIND GUSTS WILL LIKELY BE THE HIGHEST THIS MORNING AS
THE PRESSURE SURGE IS THE GREATEST. A WIND ADVISORY IS IN EFFECT FOR
MUCH OF THE NRN TIER OF THE CWA WITH GUSTS UP TO 40 KTS EXPECTED
THIS MORNING. A CHILLY DAY EXPECTED WITH TEMPS ONLY REACHING THE 20S
AND SINGLE DIGITS/TEENS IN THE MTNS. WIND CHILL HEADLINES ARE IN
EFFECT FOR THE ENTIRE REGION WITH WC VALUES 10-20 BELOW ZERO ACROSS
THE WESTERN SLOPES OF THE ALLEGHENY FRONT TO ZERO TO 5 BELOW ZERO
ACROSS THE I-95 CORRIDOR.

WINDS WILL SLOWLY TAPER OFF INTO THE EVENING HOWEVER TEMPERATURES
ARE EXPECTED TO DROP INTO THE SINGLE DIGITS AND LOW TEENS...BELOW
ZERO ACROSS THE HIGHER ELEVATIONS. WIND CHILL VALUES WILL DROP AS
WELL REACHING VERY COLD CONDITIONS EARLY SUNDAY MORNING.

&&

.SHORT TERM /SUNDAY/...HIGH PRESSURE MOVES OVERHEAD BY SUNDAY AFTERNOON
AND WINDS WILL RELAX. TEMPS WILL BE AT OR SLIGHTLY WARMER THAN
TODAY.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...ARCTIC HIGH OFF THE EAST COAST
SUN NIGHT WILL BE RETREATING QUICKLY AS MOISTURE SPREADS QUICKLY
FROM THE SOUTHWEST. SNOW BEGINS LATE SUN NIGHT AND CONTINUES THROUGH
MON MORNING DUE TO OVERRUNNING BUT WARMER AIR ALOFT MOVES IN QUICKLY
MON AFTERNOON WITH SNOW TRANSITIONING TO FZRA/PL AND RAIN. GUIDANCE
IS CONSIDERABLY WARMER BOTH ALOFT AND AT THE SURFACE AND QUICKER TO
BRING PRECIP THAN 24 HRS AGO AS MOST GFS AND ECMWF ENSEMBLE MEMBERS
NOW SHOW SFC LOW PRES TRACKING WEST OF THE APPALACHIANS. POTENTIAL
FOR SIX INCHES OF SNOW WILL BE CONFINED ONLY TO THE POTOMAC
HIGHLANDS WITH 1-3 INCHES OF SNOW ELSEWHERE EXCEPT LESS IN FAR
SOUTHERN MD. A BAND OF FZRA WITH ICE ACCUMULATIONS OF BETWEEN ONE
AND TWO TENTHS OF AN INCH CAN ALSO BE EXPECTED FROM THE POTOMAC
HIGHLANDS TO THE ROUTE 15 CORRIDOR. PRECIP SHOULD HAVE
TRANSITIONED TO ALL RAIN BY 12Z TUE IN MOST AREAS EXCEPT PERHAPS
HIGHER ELEVS. THIS TRANSITION IS ALSO FASTER THAN 24 HRS AGO.
FLOODING IS NOW A MUCH BIGGER CONCERN AS SNOWMELT AND HEAVY RAINS
ALL BECOME RUNOFF DUE TO FROZEN AND SNOW COVERED GROUND. WPC NOW
HAS MOST OF THE AREA HIGHLIGHTED FOR EXCESSIVE RAINS DAY 3 VALID
12Z MON - 12Z TUE. ADDITIONAL FLOODING PROBLEMS ARE LIKELY TO
OCCUR AS ICE IS BEGINNING TO AFFECT MOST RIVERS. MOST OF THE
PRECIP CLEARS THE AREA BY TUE NIGHT BUT UPSLOPE PRECIP MAY
CONTINUE THROUGH THURSDAY. DRY WX FOR THE END OF THE WEEK AS HIGH
PRES BUILDS.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...

PREVAILING VFR CONDITIONS EXPECTED THROUGH SUNDAY HOWEVER ISO-SCT
SNSH HAVE MOVED ACROSS THE TERMINALS EARLY THIS MORNING AND WILL
LIKELY IMPACT BWI/MTN BEFORE SUNRISE. SNOW SHOWERS HAVE A HISTORY OF
REDUCED VSBYS. ANOTHER ROUND OF ISO SNSH IS POSSIBLE THIS AFTERNOON
MAINLY ACROSS MRB/BWI/MTN HOWEVER CAN NOT RULE OUT ONE REACH
IAD/DCA. NW WINDS 20-25 KTS GUSTS UP TO 40KTS EXPECTED THIS MORNING.
WINDS WILL SLOWLY COME DOWN THIS AFTERNOON HOWEVER GUSTS 30-35KT CAN
BE EXPECTED. WINDS WILL BE SLIGHTLY LOWER AT CHO THROUGH THE DAY.

VFR CONDITIONS EXPECTED TONIGHT INTO SUNDAY. NW WINDS 10-15 G20KT
EXPECTED SUNDAY MORNING.

HEAVY PRECIP MON-TUE MORNING WITH IFR CONDITIONS EXPECTED. SNOW
LATE SUN NIGHT AND MON MORNING TRANSITIONING TO RAIN AT KDCA...KBWI
KMTN AND FZRA AT KCHO...KIAD AND KMRB. PRECIP SHOULD HAVE
TRANSITIONED TO ALL RAIN AT ALL TAF SITES BY 12Z TUE WITH PRECIP
ENDING BY TUE EVENING.

&&

.MARINE...GUSTY NORTHWEST WINDS EXPECTED TODAY BEHIND A COLD FRONT. A GALE
WARNING IS IN EFFECT FOR THE WATERS. THE GUSTY NORTHWEST WINDS WILL
CONTINUE THROUGH SATURDAY BEFORE SLOWLY DIMINISHING TONIGHT INTO
SUNDAY. THE GALE WARNING CONTINUES THROUGH SATURDAY NIGHT AND A
SMALL CRAFT ADVISORY IS IN EFFECT FOR THE WATERS SUNDAY. A FREEZING
SPRAY ADVISORY IS ALSO IN EFFECT THROUGH EARLY SUNDAY. A SMALL CRAFT
ADVISORY MAY NEEDED SUNDAY AFTERNOON.

HIGH PRESSURE WILL BUILD OVER THE WATERS LATER SUNDAY BEFORE MOVING
OFF THE EAST EARLY NEXT WEEK.

SMALL CRAFT CONDITIONS LIKELY MON NIGHT-TUE THEN WED-FRI.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR DCZ001.
     WIND CHILL ADVISORY FROM 6 PM THIS EVENING TO 9 AM EST SUNDAY
     FOR DCZ001.
MD...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR MDZ501.
     WIND CHILL WARNING UNTIL 9 AM EST SUNDAY FOR MDZ501.
     WIND CHILL ADVISORY UNTIL 9 AM EST SUNDAY FOR MDZ502.
     WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR MDZ003>006-011-
     013-014-016>018-503>508.
     WIND CHILL ADVISORY FROM 6 PM THIS EVENING TO 9 AM EST SUNDAY
     FOR MDZ003>006-011-013-014-016>018-503>508.
VA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR VAZ503.
     WIND CHILL WARNING UNTIL 9 AM EST SUNDAY FOR VAZ503.
     WIND CHILL ADVISORY UNTIL 9 AM EST SUNDAY FOR VAZ504-507-508.
     WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR VAZ028-031-
     052>054-505-506.
     WIND CHILL ADVISORY FROM 6 PM THIS EVENING TO 9 AM EST SUNDAY
     FOR VAZ025>031-036>040-050>057-501-502-505-506.
WV...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR WVZ501-
     503-505.
     WIND CHILL WARNING UNTIL 9 AM EST SUNDAY FOR WVZ501-503-505.
     WIND CHILL ADVISORY UNTIL 9 AM EST SUNDAY FOR WVZ050-055-502-
     504-506.
     WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR WVZ051>053.
     WIND CHILL ADVISORY FROM 6 PM THIS EVENING TO 9 AM EST SUNDAY
     FOR WVZ051>053.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 1 PM EST SUNDAY FOR
     ANZ530>543.
     FREEZING SPRAY ADVISORY UNTIL 1 PM EST SUNDAY FOR ANZ530>543.
     GALE WARNING UNTIL 6 AM EST SUNDAY FOR ANZ530>543.

&&

$$
SYNOPSIS...LFR
NEAR TERM...HAS
SHORT TERM...HAS
LONG TERM...LFR
AVIATION...HAS/LFR
MARINE...HAS/LFR


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