Area Forecast Discussion
Issued by NWS Sterling, VA

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280 FXUS61 KLWX 100850 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 350 AM EST WED FEB 10 2016 .SYNOPSIS...
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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.
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&& .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/...
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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.
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&& .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 /09Z 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. AM MONITORING THE UPPER TIDAL POTOMAC AS WELL. TRENDS SUGGEST THAT ADJUSTMENTS WL BE REQUIRED TO HEC-RAS GDNC. OBS TRACKING FAIRLY CLOSE TO ETSS...WHICH SUGGESTS THAT ANOTHER ADVY WL BE REQD FOR DC/ALEXANDRIA. WL BE ADDRESSING THAT SHORTLY. 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. && .EQUIPMENT... && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. 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. 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... EQUIPMENT...

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