Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 281857 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 257 PM EDT SUN JUN 28 2015 .SYNOPSIS...
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LOW PRESSURE WILL MOVE NORTHEAST FROM NEW YORK STATE TONIGHT. HIGH PRESSURE BRIEFLY BUILDS OVER THE AREA ON MONDAY. A WEAK COLD FRONT WILL CROSS THE AREA TUESDAY NIGHT...WITH A REINFORCING BOUNDARY DROPPING TOWARD THE AREA LATE WEDNESDAY BEFORE STALLING.
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&& .NEAR TERM /THROUGH MONDAY/...
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AS OF 18Z...WATER VAPOR IMAGERY DEPICTS UPR LOW CENTER NORTH OF LAKE ONTARIO. THE ASSOCIATED SFC LOW IS NEAR BUFFALO NY PER SFC WIND. A SHIELD OF STRATUS IN THE COMMA HEAD OF THE OCCLUDED LOW IS OVER THE ENTIRE NORTHERN MID-ATLANTIC...WITH WAVE BREAKS OVER THE AREA DUE TO WLY DOWNSLOPING FLOW FROM THE APPALACHIANS. THE THICKER CLOUD COVER HAS LIMITED BOTH TEMPERATURES AND WIND GUSTS TODAY AND WILL CONTINUE TO THROUGH SUNSET PER SATELLITE AND SFC OBSERVATION TRENDS. WLY WINDS WILL CONTINUE TO GUST AROUND 20 MPH. TONIGHT...THE LOW LIFTS NORTH AND THE SFC RIDGE OVER IN WILL SHIFT EAST ACROSS THE AREA. THIS WILL CLEAR CLOUDS THROUGH THE EVENING HOURS. MIXING IS EXPECTED TO CONTINUE FOR MOST PLACES...BUT PUT SOME PATCHY FOG IN THE GRIDS FOR SHELTERED VALLEYS WERE CALM AND CLEAR (AND STILL SOMEWHAT MOIST) CONDITIONS WILL MAKE FOR VALLEY FOG. MIN TEMPS MID TO UPR 50S INLAND...MID 60S NEARSHORE. MONDAY...HIGH PRESSURE BUILDS OVERHEAD IN THE MORNING...SHIFTING EAST IN THE AFTERNOON. ABUNDANT MORNING SUNSHINE WITH HIGH CLOUDS AHEAD OF THE NEXT SYSTEM ARRIVING IN THE AFTERNOON. SWLY FLOW 5- 10MPH WITH MAX TEMPS GENERALLY LOW 80S. MID 80S LIKELY DC AND SOUTH.
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&& .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
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BY MON NGT...SFC LOPRES SHUD BE INVOF THE LWR GRTLKS...W/IN BASE OF H5 TROF AXIS. RETURN FLOW WL BE SPREADING UP THE ERN SEABOARD...W/ A WMFNT IN THE AREA. ITS UNCLR HOW MUCH LIFT/FORCING WL BE PRESENT ALONG THE BNDRY...BUT GFS HAS BEEN A LITTLE MORE IMPRESSIVE WRT QPF OUTPUT. AM STILL NOT CONVINCED THERE WL BE PCPN AT NGT...BUT IF THERE WERE...IT WOULD BE MORE PLAUSIBLE IN THE PTMC HIGHLANDS AND PERHAPS ALONG THE MD/PA BRDR AS THESE AREAS HV LWR HGTS. HV ADDED CHC/SCHC SHRA TO NRN TIER OF MD...INCL METRO BALT. AREA WL BE IN WARM SECTOR ON TUE. SFC CDFNT AND MID-LVL PVA WL BE HEADING EWD...PRIMARILY AFFECTING CWFA DURING THE AFTN-EVE HRS. ITS STILL TBD HOW MUCH INSTBY WL BE PRESENT /SHUD HV SOME INSOLATION/... BUT PROFILES DEFINITELY SUGGEST THAT SHEAR WL BE AVBL. AS SUCH...WL KEEP HI CHC/LOW LKLY POPS IN GRIDS...CENTERED ON SUNSET /PK DIURNAL HTG/ IN RESPONSE TO FORCED ASCENT FM CDFROPA.
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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LONGWAVE TROUGHING OVER THE EASTERN US AND A SFC FRONT WILL BE IMPACTING THE REGION THE SECOND HALF OF THE WEEK. THE FRONT APPROACHES WED EVE AND STALLS OVER THE REGION THROUGH FRI... BUT EXACT LOCATION IS STILL UNCERTAIN. LOW PRESSURE AND ASSOCIATED COLD FRONT COULD IMPACT THE REGION FOR THE WEEKEND. UNSETTLE WEATHER IS MORE LIKELY THROUGH THIS PERIOD WITH CHANCES OF SHOWERS AND TSMTS. MAX TEMPS WILL BE IN THE MID TO UPR 80S AND LOW TEMPS IN THE 60S TO LOW 70S.
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&& .AVIATION /19Z SUNDAY THROUGH FRIDAY/...
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VFR THROUGH TAF PERIOD. STRATOCU DECK AROUND 6 KFT PERSISTS INTO THE EVENING BEFORE CLEARING AS LOW PRESSURE OVER NY STATE MOVES FARTHER NE. WLY FLOW GUSTING UP TO 20 KT THIS AFTERNOON WEAKENS TO AROUND 10 KT THIS EVENING. PATCHY FOG IN SHELTERED VALLEYS ONLY OVERNIGHT WITH MIXING ELSEWHERE UNDER CLEARING SKIES. VFR CONTINUES MONDAY AS HIGH PRESSURE BUILDS OVERHEAD. SWLY FLOW LESS THAN 10 KT. SCT TO PERHAPS NMRS TSRA AFFECTING TERMINALS ON TUE. PREFERRED TIME MID-LT DAY. MVFR-IFR RESTRUCTIONS PSBL.
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&& .MARINE...
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SCA FOR ALL WATERS UNTIL 8PM FOR WLY FLOW GUSTING AROUND 20 KT. GUSTS WOULD HAVE AROUND 25 KT IF IT WERE SUNNIER. SCA FOR MOST WATERS THROUGH MIDNIGHT...THEN FLOW WEAKENS OVERNIGHT AS LOW OVER NY STATE MOVES FARTHER NORTH. HIGH PRESSURE BUILDS MONDAY WITH SWLY FLOW 5-10 KT. SLY WINDS PICK UP MON NGT AS WMFNT MAKES ITS WAY ACRS THE WATERS. HWVR...BEST GRADIENT WINDS WL COME ON TUE AHD OF CFP. SCA PSBL AT THAT TIME. VFR CONDITIONS EXPECTED MOST OF THE TIME. SUB-VFR DUE TO PSBL SHOWERS AND TSTMS WED AND THURS.
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&& .HYDROLOGY...
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THE MONOCACY RIVER IS NEARING A CREST IN THE FREDERICK AREA. THE TWO GAUGES THERE...FDKM2 AND FRMM2 ARE BOTH IN MINOR FLOOD STAGE. THESE ARE COVERED BY THE FORECAST POINT AT FDKM2 AND WILL REMAIN IN A FLOOD WARNING UNTIL BOTH ARE BELOW FLOOD THRESHOLD. THE RIVER LEVEL ON THE WESTERN BRANCH AT UPPER MARLBORO DROPPED BELOW FLOOD STAGE JUST BEFORE 2PM EDT. THEREFORE...THE FLOOD WARNING HAS BEEN CANCELLED.
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&& .CLIMATE...
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RECORD DAILY MAXIMUMS WERE SET YESTERDAY AT DCA AND BWI AIRPORTS WITH 2.75 AND 3.11 INCHES OF RAIN RESPECTIVELY. THESE BROKE THE PREVIOUS RECORDS OF 2.59 INCHES AT DCA SET IN 1881 AND 2.04 INCHES AT BWI SET IN 1883. 1.47 INCHES OF RAIN AT DULLES TIED THE RECORD FROM 2006 JUNE 2015 IS NOW THE SECOND WETTEST JUNE ON RECORD AT DCA WITH 11.93 INCHES OF RAIN. THE WETTEST JUNE ON RECORD WAS 2006 WHEN 14.02 INCHES FELL. BWI TOTALS FOR JUNE ARE NOW UP TO 13.09 INCHES MAKING IT THE WETTEST JUNE ON RECORD BREAKING THE PREVIOUS RECORD OF 9.95 INCHES SET IN 1972. SHOWERS AND THUNDERSTORMS ARE LIKELY IN THE AREA TUESDAY AFTERNOON AND EVENING...POSSIBLY ADDING TO THESE MONTHLY TOTALS.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT MONDAY FOR ANZ530>534- 537>543. SMALL CRAFT ADVISORY UNTIL 9 PM EDT THIS EVENING FOR ANZ535- 536. && $$ SYNOPSIS...BAJ/HTS NEAR TERM...BAJ SHORT TERM...HTS LONG TERM...IMR AVIATION...BAJ/HTS/IMR MARINE...BAJ/HTS/IMR HYDROLOGY...BAJ CLIMATE...BAJ

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