Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 260107 AAA AFDLWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 907 PM EDT MON MAY 25 2015 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OFFSHORE THIS WEEK. A SOUTHERLY FLOW WILL BRING WARM HUMID CONDITIONS TO THE MID ATLANTIC THROUGH FRIDAY. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE EACH AFTERNOON AND EVENING BEGINNING TUESDAY AND LASTING THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH TUESDAY/...
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AN UPPER LEVEL RIDGE WILL MOVE FURTHER OFF THE EAST COAST TONIGHT. MID-HIGH LEVEL CLOUDS WILL MOVE INTO THE HIGHLANDS LATE TONIGHT FROM THE ACTIVITY IN THE TN VALLEY. AS UPPER RIDGE MOVES FURTHER OFF THE COAST EXPECT ASSOCIATED SUBSIDENCE INVERSION TO WEAKEN FURTHER AND ALLOW SCT SHOWERS AND T-STORMS TO DEVELOP IN THE AFTERNOON. MODELS SUGGEST SOME CONVECTION WEST OF THE APPALACHIANS WILL MOVE INTO OUR AREA UNDER A SOUTHWEST STEERING FLOW. NEW CONVECTION COULD ALSO DEVELOP EAST OF THE BLUE RIDGE MTNS. GFS PLOT OF 850 MB EQUIVALENT POTENTIAL TEMPERATURE SHOWS A MAXIMUM FROM MONTGOMERY COUNTY SOUTHWARD THROUGH DULLES TO KCHO SUGGESTING ANOTHER POSSIBLE AREA OF CONVECTIVE INITIATION.
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&& .SHORT TERM /TUESDAY NIGHT/...
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THE MID-ATLANTIC WILL BE UNDER SW FLOW ALOFT WITH THE RIDGE IN THE ATLANTIC AND MULTIPLE DISTURBANCES ARE EXPECTED TO RIDE NEAR OR OVER THE HIGHLANDS TUESDAY AFTERNOON. THE STORM MOTION WILL BE CLOSE TO 180 SO THERE WONT BE MUCH EASTWARD PROGRESSION. AREAS EAST OF THE BLUE RIDGE SHOULD STAY DRY INTO TUESDAY AFTERNOON. FLOW VEERS TO 220 BY LATE AFTERNOON AND SCT SHOWERS AND THUNDERSTORMS MAY MOVE INTO THE WESTERN SUBURBS OF DC AND BALTIMORE BY SUNSET. SHEAR AND INSTABILITY WILL BE MARGINAL DUE TO THE RIDGE STILL INFLUENCING THE AREA AND CLOUD COVER. ANY THUNDERSTORMS SHOULD STAY SUB-SVR.
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&& .LONG TERM /WEDNESDAY THROUGH MONDAY/... EARLY SUMMER WARMTH AND MOISTURE WL BE THE MAIN WX WORDS FOR THE 2ND HALF OF THE WK. HIGH PRES OFF THE CST AND FNTL BNDRY E OF THE MS RVR WL KEEP THE E CST IN WARM HUMID AIR. MDLS ARE PUTTING OUT SOME LKLY POPS. IT IS HARD TO WANT TO RAISE SUMMER CNVTCN POPS TO THAT LVL SVRL DAYS IN ADVANCE - FOR THE TIME BEING WL KEEP POPS IN CHC RANGE. CLDS WL BE ON THE INCRS TUE AND RMN THRU THU. THIS WL KEEP INSOLATION DOWN...BUT MOISTURE/SRLY FLOW WL ALSO BE KEEPING NIGHTTIME WARMTH IN. HIGHS WL BE IN THE MU80S...LOWS IN THE MU60S XCPT L70S IN THE CITIES. A COLD FRONT WILL STALL ACROSS THE EASTERN HALF OF THE REGION THURSDAY NIGHT AND FRIDAY...ALLOWING FOR ADDITIONAL SHOWERS AND THUNDERSTORMS TO DEVELOP. LOW TEMPERATURES THURSDAY NIGHT AND HIGH TEMPERATURES FRIDAY COULD STILL BE 7 TO 10 DEGREES ABOVE AVERAGE. THE COLD FRONT IS EXPECTED TO BRIEFLY RETURN NORTHWARD AS A WARM FRONT FRIDAY NIGHT BEFORE A SECOND COLD FRONT...MODERATELY-STRONG... APPROACHES THE REGION SATURDAY. SHOWERS AND THUNDERSTORMS WILL CONTINUE TO BE A THREAT FRIDAY NIGHT AND SATURDAY ALONG THE COLD FRONT. LOW TEMPERATURES FRIDAY NIGHT AND HIGH TEMPERATURES SATURDAY COULD BE 10 DEGREES ABOVE NORMAL...REACHING THE UPPER 60S AND NEAR 90...RESPECTIVELY. THE COLD FRONT SHOULD SLOWLY PUSH THROUGH THE REGION SATURDAY NIGHT INTO SUNDAY. THE EUROPEAN MODEL IS SLOWER THAN THE GFS IN DOING THIS. NONETHELESS...THE CHANCE FOR SHOWERS AND THUNDERSTORMS WILL LINGER THROUGHOUT THE PERIOD. LOWS SATURDAY NIGHT AND HIGHS SUNDAY WILL STILL BE ABOVE AVERAGE. A WEDGE OF HIGH PRESSURE WILL BUILD SOUTHWARD ALONG THE EAST COAST...HELPING TO COOL CONDITIONS DOWN A LITTLE. HOWEVER... OVERRUNNING MOISTURE FROM THE SOUTH AND PASSING MID-LEVEL DISTURBANCES TO THE NORTH COULD BRING ANOTHER THREAT FOR RAIN SHOWERS. THUNDERSTORMS SHOULD BE LIMITED. TEMPERATURES MAY BE A FEW DEGREES ABOVE NORMAL EACH PERIOD. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/...
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VFR CONDITIONS EXPECTED TODAY AND TONIGHT. -SHRA/VCTS POSSIBLE TUESDAY AFTERNOON MAINLY AT KIAD AND KCHO. VFR MAJORITY OF THE TIME TUE NGT-THU. RW/TRW WL BE PSBL... ESPECIALLY IN THE AFTN/ERLY EVE. SRLY WINDS WL GUST INTO THE L20S DURG THE AFTN. MVFR OR IFR CONDITIONS POSSIBLE AT ALL TERMINALS THURSDAY NIGHT AND FRIDAY WITH SHOWERS AND THUNDERSTORMS. WINDS GENERALLY SOUTHWEST 5 TO 10 KNOTS WITH A FEW HIGHER GUSTS.
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&& .MARINE...
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S WINDS WILL PERSIST ACROSS THE WATERS TONIGHT THROUGH THURSDAY. MIXING DURING THE AFTERNOON WILL LEAD TO SCA CONDITIONS ACROSS LOWER POTOMAC AND CHES BAY SOUTH OF POOLES ISLAND. WINDS SHOULD SUBSIDE TONIGHT ACROSS THE UPPER TIDAL POTOMAC AND CHESAPEAKE BAY NORTH OF POOLES ISLAND. THIS TREND WILL CONTINUE TUESDAY AND TUESDAY NIGHT. SRLY FLOW WL CONT OVR THE WATERS TUE NGT-THU. SCA IN EFFECT TUE NGT FOR THE LWR PTMC/MAIN PTN OF THE BAY. THIS WL LKLY NEED TO BE XTND INTO WED. RW/TRW WL BE PSBL AS WELL. NO MARINE HAZARDS EXPECTED THURSDAY NIGHT THROUGH FRIDAY.
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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 MIDNIGHT EDT TUESDAY NIGHT FOR ANZ531-538-539. SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR ANZ532>534- 537-540>543.
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&& $$ SYNOPSIS...LFR NEAR TERM...LFR SHORT TERM...HAS LONG TERM...WOODY! AVIATION...LFR MARINE...LFR

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