Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 201413 AAA AFDLWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1013 AM EDT WED MAY 20 2015 .SYNOPSIS...
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HIGH PRESSURE WILL BE IN PLACE OVER THE REGION TODAY. A LOW PRESSURE PASSING JUST TO THE SOUTH WILL PROVIDE A BIT OF RAIN TO THE AREA ON THURSDAY. ANOTHER COLD FRONT WILL MOVE IN FROM THE NORTHWEST ON FRIDAY BUT LITTLE IF ANY PRECIPITATION WILL OCCUR. HIGH PRESSURE WILL DOMINATE DURING THE WEEKEND.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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HIGH PRESSURE IS STRETCHED FROM THE NRN PLAINS TO THE UPPER MIDWEST AT PRESENT. LOW PRESSURE CENTERED OVER OKLAHOMA AND NORTHERN TEXAS WILL MOVE EAST TO THE SRN APPALACHIANS TONIGHT. A DECENT PRESSURE GRADIENT THIS MORNING WILL KEEP THE WINDS UP A BIT...BUT THE GRADIENT RELAXES THIS AFTERNOON AND WINDS SHOULD SLACKEN OFF BEFORE SUNSET. THE COOLER AND DRIER CANADIAN AIR MASS ADVECTING IN WILL KEEP TEMPS GENERALLY ABOUT 15 DEGREES COOLER THAN YESTERDAY`S READINGS...WITH A SIMILAR DROP IN DEW POINTS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... LOW PRESSURE WILL SLIDE ALMOST DUE EAST FROM OKLAHOMA...REACHING THE SOUTHERN APPALACHIANS TONIGHT AND MOVING OFF THE COAST OF NORTH CAROLINA LATER THURSDAY. TO THE NORTH OF THE LOW...WARM ADVECTION/ISENTROPIC LIFT AND FGEN SHOULD CAUSE A BAND OF LIGHT RAIN TO MOVE ACROSS THE CWA LATE TONIGHT AND THURSDAY. MODELS HAVE WAVERED ON THIS BUT MOST OF THE CURRENT GUIDANCE...GFS/EC/NAM/GGEM/RGEM/SREF...BRING AT LEAST SMALL AMOUNTS OF MEASURABLE PRECIPITATION AS FAR NORTH AS WASHINGTON DC...SO BUMPED POPS UP TO LOW END LIKELY FOR THURSDAY MORNING THAT FAR NORTH WITH CHANCE POPS IN SURROUNDING PERIODS. THIS WON`T BE A WASHOUT...BUT WITH THE COOLER AND DRIER AIR MASS ALREADY IN PLACE AHEAD OF THE SYSTEM AND A NORTHEAST WIND EXPECTED TO DEVELOP AS THE LOW MOVES BY...THURSDAY WILL BE A RATHER COOL AND UNPLEASANT DAY FOR THE LATTER PORTION OF MAY. TOOK HIGHS DOWN SEVERAL DEGREES GIVEN INCREASED CONFIDENCE IN A CLOUDY AND SHOWERY SOLUTION. LOW PRESSURE DEVELOPING OFF THE CAROLINA COAST WILL MOVE AWAY FROM THE REGION THURSDAY NIGHT. ANY REMAINING SHOWERS WILL LIKELY COME TO AN END FROM WEST TO EAST DURING THE OVERNIGHT HOURS. A COLD FRONT AND UPPER TROUGH WILL CROSS THE REGION ON FRIDAY. MOISTURE WILL BE SCARCE WITH THE FRONTAL PASSAGE. SOME OF THE MODEL GUIDANCE DOES SHOW SOME LIGHT QPF BUT WILL KEEP A DRY FORECAST ATTM. FRIDAY WILL BE COOL AND NOTICEABLY DRIER WITH HIGHS ONLY IN THE UPPER 60S TO THE MIDDLE 70S. OVERNIGHT LOWS FRIDAY NIGHT WILL DIP BACK INTO THE 40S TO LOWER 50S. && .LONG TERM /SATURDAY THROUGH TUESDAY/... HIGH PRESSURE WILL BUILD INTO THE MIDDLE ATLANTIC FROM THE WEST ON SATURDAY YIELDING VERY PLEASANT WEATHER CONDITIONS WITH AFTERNOON HIGH TEMPERATURES IN THE 70S IN MOST LOCATIONS. THE HIGH WILL MOVE OFFSHORE BY SUNDAY WHICH WILL ALLOW FOR A WARM SOUTHERLY FLOW TO DEVELOP ACROSS THE MIDDLE ATLANTIC REGION. TEMPERATURES WILL LIKELY MODERATE INTO THE UPPER 70S TO MIDDLE 80S. MONDAY AND TUESDAY...BERMUDA HIGH AND UPPER RIDGE ARE PROGGED TO SETTLE OVER THE REGION WITH HOT AND HUMID CONDITIONS POSSIBLE. AFTERNOON HIGH TEMPERATURES COULD APPROACH THE 90S...ESPECIALLY ON TUESDAY. AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE GIVEN THE DAYTIME INSTABILITY EACH DAY. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
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VFR CONDITIONS EXPECTED THROUGH 21/06Z. RAIN WILL START MOVING IN LATE TONITE WITH POSSIBLE MVFR CIGS. GUSTS UP TO 27 KT EARLY DROPPING OFF IN THE AFTERNOON. MVFR TO VFR THURSDAY NIGHT AS LOW PRESSURE PULLS AWAY TO THE NORTH AND EAST. SHOWERS WILL END OVERNIGHT. VFR EXPECTED FRIDAY THROUGH MUCH OF THE WEEKEND. AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE MONDAY AND TUESDAY AFTERNOON AND EVENING DUE TO HEAT AND HUMIDITY.
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&& .MARINE...
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NORTHWEST WINDS WILL GUST UP TO 25 KNOTS TODAY SO CONTINUED SCA AS ADVERTISED. PRESSURE GRADIENT RELAXES BY TONIGHT AND WINDS WILL SUBSIDE. SYSTEM PASSING TO THE SOUTH ON THURSDAY WILL BRING LIGHT RAIN...BUT WINDS DON`T LOOK VERY STRONG RIGHT NOW SO HAVE NOT HEADLINED ANY ADDITIONAL SCA POTENTIAL. WINDS WILL REMAIN BELOW SCA THURSDAY NIGHT BUT COULD APPROACH CRITERIA IN GUSTS WITH THE FRONTAL PASSAGE EARLY FRIDAY...ESPECIALLY OVER THE BAY AND AGAIN EARLY SATURDAY. WINDS ARE EXPECTED TO MOSTLY REMAIN BELOW SCA THROUGH EARLY NEXT WEEK ALTHOUGH SOME SHOWER AND THUNDERSTORM ACTIVITY MAY BE POSSIBLE DURING EACH AFTERNOON AND EVENING ON MONDAY AND TUESDAY.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR ANZ530>543. && $$ SYNOPSIS...RCM/LFR NEAR TERM...LFR SHORT TERM...RCM/KRW LONG TERM...KRW AVIATION...RCM/KRW MARINE...RCM/KRW

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