Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 200754 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 354 AM EDT WED MAY 20 2015 .SYNOPSIS...
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HIGH PRESSURE WILL BUILD IN FROM THE WEST TODAY IN THE WAKE OF YESTERDAY`S COLD FRONTAL PASSAGE. TEMPERATURES WILL BE COOLER AND HUMIDITY WILL BE LOWER. 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 SATURDAY AND SUNDAY. THE RISK OF SHOWERS AND THUNDERSTORMS WILL INCREASE ON MEMORIAL DAY.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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HIGH PRESSURE IS CENTERED OVER THE NORTHERN PLAINS AT PRESENT...WITH THE COLD FRONT THAT PASSED YESTERDAY NOW ALONG THE EAST COAST AND ANOTHER LOW PRESSURE CENTERED OVER OKLAHOMA AND NORTHERN TEXAS. 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. COMBINED WITH MOSTLY SUNNY SKIES...AND TODAY WILL BE A VERY PLEASANT ONE.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
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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.
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/...
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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.
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&& .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
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VFR CIGS AND VIS THRU AT LEAST EARLY TONIGHT AS HIGH PRESSURE BUILDS IN FROM THE WEST. NORTHWEST WINDS WILL BE A BIT GUSTY TODAY WITH THE COLD ADVECTION AND SOME GUSTS ABOVE 20 KNOTS ARE NOT OUT OF THE QUESTION. SYSTEM PASSING TO THE SOUTH MAY RESULT IN MVFR CIGS AND VIS LATE TONIGHT AND THURSDAY AS LIGHT RAIN OVERSPREADS THE REGION. 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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GUSTY NORTHWEST WINDS WILL LIKELY REACH 20-25 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 AND PERHAPS MIST...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...
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DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR ANZ530>543.
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&& $$ SYNOPSIS...RCM NEAR TERM...RCM SHORT TERM...RCM/KRW LONG TERM...KRW AVIATION...RCM/KRW MARINE...RCM/KRW

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