Area Forecast Discussion
Issued by NWS Sterling, VA

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272
FXUS61 KLWX 100959
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
459 AM EST WED FEB 10 2016

.SYNOPSIS...
LOW PRESSURE IMPACTS THE AREA TODAY BEFORE PUSHING OFF TO THE
NORTHEAST. HIGH PRESSURE BUILDS IN THE WAKE THROUGH FRIDAY WITH A
STRONG COLD FRONT CROSSING THE REGION TO START THE WEEKEND. ARCTIC
HIGH PRESSURE BUILDS IN FOR THE WEEKEND. LOW PRESSURE MAY IMPACT
THE MID-ATLANTIC MONDAY INTO TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
SFC TROUGH EXTENDING ALONG THE I-95 CORRIDOR EARLY THIS MORNING
WHILE SHORTWAVE ENERGY PIVOTS ALONG THE UPPER LVL TROUGH. THE
COMBINATION HAVE TRIGGERED LIGHT SNOW SHOWERS...CURRENTLY BEING
NOTED ALMOST EVERYWHERE EAST OF THE BLUE RIDGE. QPF IS LIGHT WITH
THESE...GENERALLY LOOKING AT A TENTH...MAYBE TWO TO THREE TENTHS
OF AN INCH IN ISOLATED SPOTS (NORTH OF BALTIMORE). LOOKING
WEST...CONTINUING UPSLOPE SNOW SHOWERS WITH WNW FLOW AND
ENHANCEMENT FROM ENERGY IN THE AFOREMENTIONED UPPER LVL TROUGH.
HIGHER SNOW AMTS OUT ON THE ALLEGHENY FRONT...WITH ADDITIONAL 2-4
INCHES PSBL THRU THURS. THE WINTER WEATHER ADVISORY REMAINS IN
EFFECT...THOUGH WILL BE EXTENDED THRU THURS TO ACCOUNT FOR THE
CONTINUING SNOW.

FOR TODAY...THE SNOW WILL TAPER OFF THIS MORNING SHORTLY AFTR
DAYBREAK AS THE SFC TROUGH SINKS SOUTH AND THE SHORTWAVE MOVES
OFFSHORE. THE UPPER LVL TROUGH WILL SLOWLY LIFT NORTH...ACTING AS
THE FORCING MECHANISM FOR ANY SNOW DEVELOPMENT TODAY INTO TONIGHT.
OUTSIDE OF THE ALLEGHENY FRONT...EXPECTING GENERALLY DRY THRU MID
DAY. FLURRIES BECOME PSBL MAINLY NORTHERN HALF OF THE CWA THIS AFTN
AS THE NEXT SHORTWAVE ENERGY TRAVERSE THE REGION. AS AS SFC TROUGH
BUILDS NORTH TONIGHT...THIS COMBINED WITH THE ENERGY ALOFT COULD
TRIGGER ISO SNOW SHOWERS MAINLY EAST OF THE I-95 CORRIDOR. SNOW
TOTALS WILL BE LIGHT...AT MOST ANOTHER TENTH TO TWO-TENTHS OF AN
INCH.

THE NEXT CONCERN WILL BE TONIGHT WITH THE COLDER TEMPS FINALLY MVG
IN ON THE FIRST OF A FEW CAA SURGES. LOWS DROPPING INTO SINGLE
DIGITS TO LOW 20S. WITH THE SURGE OF COLDER AIR...EXPECTING GUSTS
INTO THE 20S AND ISOLATED SPOTS ON THE RIDGES INTO THE 30S. THESE
TWO FACTORS COMBINED WILL PRODUCE BELOW ZERO WIND CHILLS PORTIONS OF
THE POTOMAC HIGHLANDS. THUS HAVE ISSUED A WIND CHILL ADVISORY FOR
THE WESTERN TIER OF COUNTIES AND THE BLUE RIDGE ZONES TO ACCOUNT FOR
WIND CHILLS LESS THAN -10 DEGREES. EVERYWHERE ELSE WILL SEE SINGLE
DIGIT WIND CHILLS.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
THE UPPER LVL TROUGH CONTINUES TO LIFT NORTH THURSDAY...FINALLY
WEAKENING/MOVING OUT OF THE REGION BY FRIDAY MORNING. UPSLOPE SNOW
SHOWERS CONTINUE DURING THE DAY...FINALLY EXPECTING TO TAPER OFF
THURS NIGHT AS A DRIER AIRMASS SETTLES INTO THE REGION. WINDS ALSO
BEGIN TO SHIFT TO THE SOUTH. HAVE SLIGHT CHC POPS RIGHT ALONG THE
MASON-DIXON DURING THE DAY TO ACCOUNT FOR ANY SNOW
SHOWERS/STREAMERS...WITH THE REMAINDER OF THE CWA REMAINING DRY.
TEMPS SHOULD WARM ENOUGH TO ALLOW FOR THE WIND CHILL ADVISORY TO
NOT NEED TO BE EXTENDED THROUGH THE DAY. WHILE TEMPS THURS NIGHT
WILL BE COLDER THAN TONIGHT...AS HIGH PRESSURE BUILDS INTO THE
REGION...EXPECTING LIGHTER WINDS AND THUS NOT AS LOW WIND CHILLS.
ISOLATED SPOTS MAY REACH CRITERIA LVL...BUT ATTM NOT ANTICIPATING
NEEDING AN ADVISORY.

ZONAL FLOW AND HIGH PRESSURE WILL ALLOW TEMPS TO BE SLIGHTLY WARMER
ON FRIDAY. DRY WX INITIALLY FRI MORNING...HOWEVER THE DRY WX WILL BE
SHORT LIVED AS A SFC TROUGH SETS UP OVER THE WESTERN HALF OF THE
CWA...TRIGGERING SNOW SHOWERS. THIS TROUGH WILL MOVE EAST DURING THE
DAY...FOLLOWED BY A POTENT COLD FRONT WHICH IS EXPECTED TO CLEAR THE
REGION BY 12Z. THIS FRONTAL PASSAGE WILL BRING THE CHC FOR SNOW
SHOWERS FRI INTO FRI NIGHT THOUGH WITH SUCH A DRY AIRMASS HAVING
BEEN IN PLACE...THE QUICK PROGRESSION OF THE FRONT LEAVES LITTLE
TIME FOR INCRSG MOISTURE AND THUS SNOW AMTS OUTSIDE OF THE UPSLOPE
REGION LOOK TO BE LITTLE. A COUPLE OF INCHES WILL BE PSBL WITH
UPSLOPE SNOW.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
STRONG CAA WILL AFFECT CWFA SAT-SAT NGT AS THE TROF AXIS AND
DEEPENING SFC LOW PULLS AWAY FROM AREA. H8 TEMPS PLUNGING BELOW -20C
SUGGEST THAT SFC TEMPS WL BE STRUGGLING TO RISE ABOVE THE LWR-MID
20S...AND LKLY WL BE STAYING IN THE TEENS W OF THE BLURDG. IN
ADDITION...MDL SNDGS LOOK TO BE WELL MIXED...W/ AT LEAST 25-30 KT
AVBL TO TRANSPORT DOWN. FCSTS WL BE CONSERVATIVE...BUT THIS
TEMP/WIND COMBO WL KEEP WIND CHILLS IN THE SINGLE DIGITS MOST OF THE
DAY. NIGHTFALL WL ONLY EXASCERBATE THE SITUATION. MIN-T SINGLE
DIGITS /BLO ZERO MTNS/ AND WINDCHILLS BLO ZERO AREAWIDE. WIND CHILL
ADVYS LKLY FOR THIS TIME PERIOD...AS ALREADY IN HWO.

HIPRES WL BUILD ACROSS THE AREA SUNDAY...WHICH WL AT LEAST REDUCE
THE WINDS. TEMPS STILL QUITE COLD THO...BOTH MAXT AND MIN-T SUN NGT.
WL BE THE RECIPIENT OF RETURN FLOW BY SUN NGT...WHICH WL SPREAD CLDS
BACK ACRS THE AREA. IT ALSO MEANS THAT PCPN WL BE APPROACHING.

MON-TUE LOOKS TO BE A MESSY TIME FRAME...AS SRN STREAM LOPRES TRACKS
ACRS THE CONUS...TRANSFERRING ITS ENERGY TO INDUCE CYCLOGENESIS.
GDNC SOLNS AT ODDS AS TO WHERE THE LOW WL TRACK...WHICH MAKES THE
DIFFERENCE BETWEEN A QUICK DOSE OF PCPN AND A MORE PROLONGED
EVENT...AS WELL AS PTYPE. AT THIS POINT...NEED TO CONSIDER PSBLTY
OF AN INLAND SOLN...WHICH MEANS NO PTYPE CAN BE RULED OUT.

&&

.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
GENERALLY VFR CONDITIONS FOR THE TAF PERIOD. BRIEF PERIOD OF MVFR
CIGS/VIS AT KDCA/KBWI/KMTN EARLY THIS MORNING WITH LIGHT SNOW
IMPACTING THOSE TERMINALS. VFR SHOULD RETURN BY 12Z. INCRSG W
WINDS TODAY...SUSTAINED 10-15 KTS WITH GUSTS 20-25 KTS. A BRIEF
LULL IN THE GUSTS WILL BE PSBL 22-03Z WITH INCRSG WINDS AGAIN
OVERNIGHT.

VFR CONDITIONS THURS THRU FRI NIGHT. LIGHT SNOW PSBL ON THURS...WITH
MINIMAL RESTRICTIONS. GUSTY NW WINDS...WITH SUSTAINED 15-20 KTS AND
GUSTS 25-30 KTS.

VFR CONDS XPCTD THIS WKND. NW WINDS WL BE PRIMARY OPERATIONAL
CONCERN /ON SAT/ WITH GUSTS WELL INTO THE 20S IF NOT LWR 30S /KTS/.

&&

.MARINE...
SCA IN EFFECT WITH WINDS GUSTING BETWEEN 20-25 KTS ON ALL
WATERS. THE SCA WILL REMAIN IN EFFECT FOR ALL WATERS THRU
THURSDAY...AND THEN ON THE CHESAPEAKE BAY WATERS THURS NIGHT. OCNL
LULLS IN THE WINDS WILL BE PSBL THIS AFTN. WHILE GUSTS GET CLOSER TO
30 KTS THURS MORNING...ATTM THE STRONGEST WINDS IN THE ML ARE 32
KTS. WILL CONTINUE WITH SCA FOR NOW AND LET SUBSEQUENT SHIFTS
DETERMINE IF A GALE WARNING IS NECESSARY.

DEEP MIXING IN NW FLOW SAT-SAT NGT...W/ MEAN LYR WINDS SUGGESTING
THAT GALES WL BE PSBL. HV GRIDS W/IN GLW CRITERIA...SPCLY ON THE
OPEN WATERS. MENTION IN HWO AND MARINE SYNOP.

HIPRES BLDS SUN. DECREASING SPDS WL RESULT...BUT MAY STILL HV SCA
CONDS ON A PORTION OF THE WATERS.

&&

.TIDES/COASTAL FLOODING...
WNWLY FLOW HAS OVERSPREAD THE AREA AND WILL CONTINUE FOR THE NEXT
COUPLE OF DAYS. WHILE THIS WILL AIDE IN PUSHING SOME OF THE EXCESS
WATER OUT OF THE ESTUARY...WE NEED TRUE NW TO CREATE A BLOWOUT. DONT
THINK THAT IS GOING TO HAPPEN.

WATER LEVELS REMAIN JUST OVER 2 FEET ABOVE ASTRO NORMS ON THE
BAY/LWR TIDAL POTOMAC...AND BELIEVE THIS WILL SLOWLY RECEDE THROUGH
THE DAY AHEAD. AS A RESULT...THE UPCOMING TIDE WILL BE HIGHER THAN
ASTRO PREDICTIONS...AND WILL BE TRIGGERING CAUTION STAGES. ANNE
ARUNDEL/CALVERT/ST MARYS CNTYS CURRENTLY UNDER ADVYS. DO NOT BELIEVE
ADVYS WL BE NECESSARY ELSEWHERE ALONG THE WESTERN SHORE OF THE BAY
THIS CYCLE.

HAVE UPDATED FORECASTS ON THE UPPER TIDAL POTOMAC TO FIT GOING
TRENDS...WHERE TIDAL ANOMALIES ARE RUNNING AROUND 2 1/3 FT ABV
ASTRO PREDICTIONS. THAT SUGGESTS THAT A SOLID MINOR INUNDATION
WILL OCCUR AT HIGH TIDE THIS MORNING. ADVISORIES HAVE BEEN ISSUED
FOR ALEXANDRIA AND DC.

LATEST INDICATIONS SUGGEST THAT THERE MAY ALSO BE MINOR INUNDATION
ISSUES AT ST GEORGES ISLAND ALONG WITH THE UPPER TIDAL POTOMAC ON
THE PM TIDE CYCLE. SINCE OVERALL TRENDS WILL BE FOR DECREASING
LEVELS...WILL BE TAKING IT ONE TIDE CYCLE AT A TIME TO BE ABLE TO
INCORPORATE ONGOING CONDITIONS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...COASTAL FLOOD ADVISORY UNTIL NOON EST TODAY FOR DCZ001.
MD...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EST
     THURSDAY FOR MDZ501.
     WINTER WEATHER ADVISORY UNTIL 6 PM EST THURSDAY FOR MDZ501.
     COASTAL FLOOD ADVISORY UNTIL 8 AM EST THIS MORNING FOR MDZ014-
     017-018.
VA...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EST
     THURSDAY FOR VAZ503-504-507-508.
     WINTER WEATHER ADVISORY UNTIL 6 PM EST THURSDAY FOR VAZ503.
     COASTAL FLOOD ADVISORY UNTIL NOON EST TODAY FOR VAZ054.
WV...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EST
     THURSDAY FOR WVZ501-503-505-506.
     WINTER WEATHER ADVISORY UNTIL 6 PM EST THURSDAY FOR WVZ501-503-
     505.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ530>534-
     537>543.
     SMALL CRAFT ADVISORY UNTIL 8 PM EST THURSDAY FOR ANZ535-536.

&&

$$
SYNOPSIS...HTS
NEAR TERM...SEARS
SHORT TERM...SEARS
LONG TERM...HTS
AVIATION...SEARS/HTS
MARINE...SEARS/HTS
TIDES/COASTAL FLOODING...HTS



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