Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 121511
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1011 AM EST FRI FEB 12 2016

.SYNOPSIS...
HIGH PRESSURE BUILDS IN ACROSS THE REGION TODAY. A STRONG COLD
FRONT WILL CROSS THE REGION TONIGHT WITH ARCTIC HIGH PRESSURE
BUILDING IN ITS WAKE FOR THE WEEKEND. LOW PRESSURE WILL IMPACT THE
AREA MONDAY AND TUESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A POTENT COLD FRONT WILL MOVE THROUGH THE MIDWEST INTO THE OHIO
VALLEY TODAY. HIGH AND MID-LEVEL CLOUDS WILL CONTINUE TO THICKEN
OVERHEAD AHEAD OF THE SHORTWAVE ENERGY ASSOCIATED WITH THE COLD
FRONT.

THE SHORTWAVE ENERGY WILL MOVE INTO THE AREA LATE THIS AFTERNOON
FROM THE WEST. THIS ENERGY WILL COMBINE WITH FORCING ALONG AND
AHEAD OF THE COLD FRONT FOR SNOW SHOWERS TO BREAK OUT ACROSS THE
WESTERN PORTION OF THE CWA. MAX TEMPS WILL BE WELL BELOW
CLIMO...RANGING FROM THE TEENS AND 20S IN THE MOUNTAINS TO THE
LOWER 30S IN WASHINGTON AND BALTIMORE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
CFP TNGT...BRINGING A HOST OF POTL HAZARDS. ISSUES ARE WINDS...
SNOW... AND WIND CHILL.

SNOW...PARAMETERS LOOKING FAVORABLE FOR A BRIEF PERIOD OF SNOW
COINCIDENT W/ THE FNT TNGT.  SCALE OF THREAT LKLY FINER THAN
GDNC...SO AM ABV MOS. ACCUMS WUD BE UNDER AN INCH...AND WUD BE ONT
HE ERN SHORE BEFORE MIDNGT.

IN THE MTNS...THE TRAJ FVRBL FOR UPSLP TNGT-SAT...AND THE DRY AMS
WUD LEAD TO A HIGH SNOW RATIO. THIS WL ACCUM SVRL INCHES. HWVR...AM
JUST UNDER ADVY CRITERIA...WHICH IS SOMEWHAT FITTING SINCE SNOW
GROWTH ZONE LOW...AND NOT INTERSECTING THE BEST LIFT.

WINDS...ATMOS WL BE WELL MIXED IN STRONG CAA POST-FRONT. MDL SNDGS
SUGGEST 30-SOMETHING KT GUSTS. WUDNT RULE OUT A FEW 40 KTS.
CONFIDENCE NOT QUITE THERE FOR WIND ADVYS. ADMITTEDLY ITS CLOSE FOR
THE MTNS.

TEMPS...CONTINING TEMP FCSTS ON THE LOW END OF GDNC...BOTH MIN-T
TNGT AND MAXT SAT.

WIND CHILLS...COMBINE THE PREV TWO BULLETS...AND WIND CHILLS WL
DEFINITELY BE A FACTOR. BEST CHC AT ADVY IN THE MTNS. IT FALLS ABT 5-
10 DEGF SHORT ELSW. PROJECTING ONWARD THOUGH...THE MTNS ALMOST
THREATEN WIND CHILL WARNING CRITERIA...SPCLY SAT NGT INTO SUN.
ELSW...FCST VALUES FLIRT W/ ADVY CRITERIA SAT NGT-SUN. MINDFUL THAT
WE/RE SVRL CYCLES OUT...AND NOTHING SEEMS SLAM-DUNK OTHER THAN WIND
CHILL ADVYS IN THE MTNS...WUD RATHER NOT MAKE FIRM WRNG/ADVY
DECISION YET. COGNIZANT OF THE THREAT THO...WL BE ISSUING WIND CHILL
WATCHES FOR THE MTNS...WHERE VALUES ARE THE LOWEST. OTHER COUNTIES
WL BE CARRIED IN THE HWO. HOPEFULLY...LATER SHIFTS WL BE ABLE TO
MAKE BETTER-INFORMED DECISIONS.

BY SUN...THE RDG WL BE OVERHEAD...AND THE ONLY HAZARD LEFT WL BE
COLD TEMPS.  MAY HV PCPN RETURNING LT SUN NGT AHD OF NXT SYSTEM. HV
CHCS TO COVER. MORE IN LONG TERM DSCN.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
ARCTIC HIGH PRESSURE WILL BE
RETREATING QUICKLY ON MON WITH MOISTURE ADVANCING QUICKLY NORTHWARD
AHEAD OF A SRN STREAM SYSTEM FOR A POTENTIAL BIG MESS MON-TUE WITH
HEAVY PRECIP AMOUNTS. POTENTIAL FOR 6+ INCHES OF SNOW APPEARS TO BE
MAINLY CONFINED TO THE POTOMAC HIGHLANDS WITH SIGNIFICANT ICING FROM
THERE TO THE ROUTE 15 CORRIDOR AND LIGHT WINTRY PRECIP TO MOSTLY
RAIN EAST OF THERE. THERE IS GENERAL CONSENSUS BETWEEN MODELS TO
BRING SFC TEMPS ABV FREEZING EVERYWHERE BY 18Z TUE WITH 50S POSSIBLE
OVER EASTERN AREAS AS H85 TEMPS CLIMB ABV 5C AS STRONG SRLY WINDS
DEVELOP. IN ADDITION TO WINTRY PRECIP CONCERNS...LATEST 00Z ECMWF
INDICATES HEAVY PRECIP AMOUNTS UP TO 3.5 INCHES WATER EQUIVALENT
WHICH COULD LEAD TO FLOODING ISSUES. WARMER TEMPS...RUNOFF AND
SNOWMELT COULD LEAD TO ICE JAM FLOODING PROBLEMS ESPECIALLY AFTER
THIS WEEKEND`S FRIGID AIR MASS.

BY MID WEEK...SRN STREAM SYSTEM MERGES/PHASES WITH A NRN STREAM
DISTURBANCE OVER THE NORTHEAST WITH SYSTEM INTENSIFYING RAPIDLY
LEADING TO STRONG NW FLOW AND DRYING CONDITIONS.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS WITH MID-LEVEL CLOUDS TODAY. CDFNT COMING THIS
EVNG...PERHAPS ACCOMPANIED BY A FEW SHSN. AREAL CVRG/CONFIDENCE IN
A PT FCST THE CONCERN. THUS...THESE DO NOT APPEAR IN TAFS ATTM.
WUD HV BREIF IFR IF AIRFIELD AFFECTED.

WINDS BECOME NW AND PICK UP POST-FRONT...WITH SOME GUSTS IN THE MID
30S AFTR MIDNGT TNGT THRU SAT AFTN.

HIPRES BLDS SAT NGT-SUN. WINDS GRDLY DIMINISHING. NO OTHER
RESTRICTIONS ANTICIPATED.

SIG WINTER STORM TO IMPACT THE REGION MON-TUE WITH HEAVY WINTRY
PRECIP MON-MON NIGHT ALONG AND WEST OF THE BLUE RIDGE ESPECIALLY AT
KCHO...KIAD AND KMRB BEFORE IT TURNS TO ALL RAIN TUE AFTERNOON. IFR
CONDITIONS LIKELY MON-TUE.

&&

.MARINE...
NO MARINE HEADLINES ANTICIPATED THROUGH THIS AFTERNOON. CDFNT
COMING TNGT...PRODUCING NW WINDS W/ 30-40KT GUSTS. THREAT WUD LKLY
BEGIN ARND/JUST AFTR MIDNGT. FOR SIMPLICITY...HV RAISED GLW
TNGT...AND CARRIED IT THRU SAT NGT. SCA LKLY ON SUN... WHICH CAN
BE ADDRESSED LATER.

SMALL CRAFT CONDITIONS LIKELY MUCH OF NEXT WEEK.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WIND CHILL WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
     MDZ501-502.
VA...WIND CHILL WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
     VAZ503-504.
WV...WIND CHILL WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
     WVZ501>506.
MARINE...FREEZING SPRAY ADVISORY FROM 3 AM SATURDAY TO 6 AM EST SUNDAY
     FOR ANZ530>543.
     GALE WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY FOR
     ANZ530>543.

&&

$$
SYNOPSIS...HTS
NEAR TERM...BJL/HTS
SHORT TERM...HTS
LONG TERM...LFR
AVIATION...BJL/LFR/HTS
MARINE...BJL/LFR/HTS


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