Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 230227 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 927 PM EST SUN FEB 22 2015 .SYNOPSIS... HIGH PRESSURE WILL BUILD INTO THE REGION OVERNIGHT. THE HIGH WILL MOVE OFFSHORE ON TUESDAY. A COLD FRONT IS EXPECTED TO PASS THROUGH TUESDAY NIGHT INTO WEDNESDAY. HIGH PRESSURE WILL RETURN FOR THE LATTER PORTION OF THE WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 02Z OBS SHOWING MUCH OF REGION AOA FREEZING...WITH COLDEST TEMPS ALONG AND E OF I-95. SHEN VALLEY STILL IN UPPER 30S AND DCA STILL AT 41F AT 02Z. 00Z KIAD SOUNDING SHOWS STRONG INVERSION OFF THE SFC ALONG WITH WIDE DWPNT DEPRESSIONS BEFORE ANOTHER INVERSION AT H85. MANY OF THE HI-RES MODELS DURING THE LATE AFT/EARLY EVNG HAVE BEEN EMPHATIC IN BRINGING IN OVC CIGS AROUND 5KFT A FEW HOURS INTO THE MODEL RUNS...BUT THE ONLY OBS SITE HAVING THAT LEVEL OF CLOUDS IS KCHO. WSR-88D AT 02Z SHOWING ALTO DECK MOVING INTO THE REGION IN SW PORTION OF CWA. WITH THE MID AND HIGH CLOUDS MOVING INTO THE REGION...NOT EXPECTING MUCH RADIATIONAL COOLING OVERNIGHT. TEMPS HAVE RUNNING SLIGHTLY ABOVE GUIDANCE AT 02Z...SO HAVE RAISED TEMPS A FEW DEGREES. COLD AIR WILL FILTER INTO THE REGION GRADUALLY OVERNIGHT THROUGH 09Z...THEN THE WINDS WILL PICK UP WITH STRONGER LLVL CAA. WINDS SHOULD BE GUSTING 20-30 MPH BY DAWN AS COLD AIR FILTERS IN BREAKING THE INVERSION LATE TONIGHT. BIG QUESTION OVERNIGHT WILL BE HOW WIDESPREAD THE FOG FORMATION WITHIN CWA WHERE SFC DEWPOINT DEPRESSIONS HAV BECOME VERY LOW OR ZERO. CURRENTLY THIS IS LIMITED TO AREAS ALONG AND E OF I-95 NEAR THE BAY...FOR EXAMPLE FREEZING FOG IN ANNAPOLIS AT 02Z PER MD SHA. BELIEVE THAT THE BEST FOG WILL BE IN AND AROUND KCHO AND ALONG THE WESTERN SHORE OF THE BAY. HAVE ISSUED SPS FOR BLACK ICE WHICH WOULD INCORPORATE FREEZING FOG HAZARDS. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... CLEARING TRENDS FOR MONDAY...WITH A COLD AND BRISK DAY EXPECTED MONDAY. TEMPS ONLY CLIMBING A FEW DEGREES INTO THE UPPER TEENS TO UPPER 20S...ALONG WITH A GUSTY NW WIND THROUGH THE DAYLIGHT HOURS. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... THE BIG STORY IN THE 1ST PART OF THE XTND WL BE RETURN OF THE COLD AIR. THIS MRNG THE UPPER MIDWEST XPRNCD LOWS OF -15 TO -29. THAT AIR WL BE MOVG INTO THE MID ATLC..ALTHO A MODIFIED VERSION. W/ HIGH PRES AND SNOW CVR LOWS WL BE SUB ZERO IN THE HIGHLANDS... SINGLE DIGITS OUTSIDE OF THE MAJOR CITIES...L TEENS IN BALT/DC. TUE SHOULD SEE QUITE A BIT OF SUNSHINE...BUT AIR TEMPS WL STRUGGLE TO REACH FRZG. TEMPS AGN XPCTD TO DROP TO WELL BLO FRZG TUE NGT. AS ROADS WL WARM TO ABV FRZG DURG TUE IT IS LKLY THAT SOME MELTING DURG DAY/REFRZG TUE NGT WL OCCUR. ANOTHER CD FNT IS XPCTD TO PUSH THRU THE RGN WED. AT THIS TIME IT APPEARS TO BE A DRY FNTL PASSAGE. THURSDAY THROUGH SUNDAY/... ARCTIC HIGH PRESSURE BUILDS INTO THE AREA OVERNIGHT WEDNESDAY..WITH COLD AND DRY WEATHER OVER THE CWA. 00Z ECMWF/GEFS HAVE SIMILAR TRACK FOR NEXT LOW PRESSURE SYSTEM DEVELOPING IN THE GULF ON THURSDAY...WILL NOT INCLUDE ANY POPS AT THIS TIME AS IMPACTS APPEAR TO STAY TO OUR SOUTH THRU THURSDAY. MODELS BEGIN TO DIVERGE SIGNIFICANTLY BEYOND THURSDAY...WITH SOME MODELS MOVING PIECES OF ENERGY TO OUR SOUTH FRIDAY AND AGAIN ON SATURDAY...BRINGING PRECIPITATION TO PARTS OF THE CWA. OTHERS KEEP OUR ENTIRE AREA COMPLETELY DRY. FOR NOW WILL KEEP PREVIOUS FORECAST OF SLIGHT CHANCE POPS GOING LATE FRIDAY NIGHT THROUGH SUNDAY. REGARDLESS...AIR TEMPERATURES WILL BE WELL BELOW NORMAL THROUGH AT LEAST SATURDAY EVENING. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... BEST CHANCE WILL BE AT CHO. WINDS WILL HELP MIX OUT ANY LOW LEVEL MOISTURE BY MONDAY MORNING. VFR CONDITIONS EXPECTED MONDAY WITH W WINDS 10-15KTS GUSTS AOB 30KTS. VFR CONDS XPCTD MON NGT-WED. && .MARINE... DELAYED THE ONSET OF THE SCA FROM 06Z TO 09Z UNDER STRONG INVERSION CONDITIONS. A PRESSURE SURGE WILL CAUSE WEST WINDS TO INCREASE ACROSS THE WATERS AFTER MIDNIGHT TONIGHT AND CONTINUE THROUGH THE DAY MONDAY. W WINDS 10-1 5KT GUSTS AOB 30 KTS POSSIBLE. SCA CONDS XPCTD TO CONT FOR THE 1ST HALF OF MON NGT AS WIND CONT TO GUST TO 20 KT. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...WIND CHILL ADVISORY FROM 6 AM MONDAY TO 9 AM EST TUESDAY FOR MDZ501. VA...NONE. WV...WIND CHILL ADVISORY FROM 6 AM MONDAY TO 9 AM EST TUESDAY FOR WVZ501-503. MARINE...SMALL CRAFT ADVISORY FROM 4 AM MONDAY TO 1 AM EST TUESDAY FOR ANZ530>543. && $$ NEAR-TERM UPDATE...LEE

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