Area Forecast Discussion
Issued by NWS Sterling, VA

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294 FXUS61 KLWX 101447 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 947 AM EST WED FEB 10 2016 .SYNOPSIS...
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LOW PRESSURE OVER NEW ENGLAND WILL PUSH OFF TO THE NORTHEAST. HIGH PRESSURE WILL BUILD INTO THE MID ATLANTIC THROUGH FRIDAY. A STRONG COLD FRONT WILL CROSS THE REGION FRIDAY NIGHT. ARCTIC HIGH PRESSURE BUILDS IN FOR THE WEEKEND. LOW PRESSURE MAY IMPACT THE AREA MONDAY AND TUESDAY.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AN UPPER LVL TROUGH WILL SLOWLY LIFT NORTH TDA...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 TRAVERSES THE REGION. TOTALS WILL BE LIGHT...AT MOST ANOTHER TENTH TO TWO-TENTHS OF AN INCH. THE NEXT CONCERN WILL BE TONIGHT WITH THE COLDER TEMPS 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. A WIND CHILL ADVISORY IS IN EFFECT 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.
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&& .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 FRIDAY MORNING. UPSLOPE SNOW SHOWERS CONTINUE DURING THE DAY...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 SO THAT THE WIND CHILL ADVISORY WL NOT NEED TO BE XTND 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 FRIDAY. DRY WX INITIALLY FRI MORNING...HOWEVER THIS WILL BE SHORT LIVED AS A SFC TROUGH SETS UP OVER THE WESTERN HALF OF THE CWA...TRIGGERING SNOW SHOWERS. THIS WILL MOVE EAST DURING THE DAY...FOLLOWED BY A POTENT COLD FRONT WHICH WILL BRING THE CHC FOR SNOW SHOWERS FRI INTO FRI NIGHT. 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 /15Z WEDNESDAY THROUGH SUNDAY/...
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VFR CONDITIONS FOR THE TAF PERIOD. 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/.
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&& .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...
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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. DON`T 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.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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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. 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.
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&& $$ UPDATE...WOODY! PRVS...APS/HTS

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