Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 250758 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 358 AM EDT MON APR 25 2016 .SYNOPSIS...
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HIGH PRESSURE WILL MOVE FURTHER OFFSHORE THROUGH TUESDAY. A COLD FRONT WILL CROSS THE AREA TUESDAY EVENING. WEAK HIGH PRESSURE BUILDS TUESDAY NIGHT THROUGH EARLY THURSDAY. ANOTHER COLD FRONT IS EXPECTED THURSDAY NIGHT. HIGH PRESSURE BUILDS FOR THE WEEKEND.
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&& .NEAR TERM /THROUGH TONIGHT/...
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DEVELOPING S TO SW FLOW WILL USHER IN WARMER TEMPS TODAY WITH 80S IN MANY PLACES XCPT 70S NCNTRL AND NORTHEAST MD AND THE HIGHER ELEVS. A FEW POP UP SHOWERS POSSIBLE OVER THE POTOMAC HIGHLANDS AND SRN BLUE RIDGE MTNS. ONLY TRACE AMTS EXPECTED. MILD AND INCREASINGLY HUMID TONIGHT WITH LOWS UPPER 50S TO LOW 60S. A FEW SHOWERS COULD MAKE IT TO THE NCNTRL MD COUNTIES TOWARD DAYBREAK TUE AS CDFNT MOVES ACROSS PA.
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&& .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
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WARMER ON TUE AS SW FLOW STRENGTHENS AHEAD OF A CDFNT. TEMPS EXPECTED IN THE MID 80S AND MAY APPROACH 90F IF THE WARMER ECMWF GUIDANCE VERIFIES. BEST MOISTURE WILL BE OVER THE NRN HALF OF THE FCST AREA WHERE SHOWERS AND T-STORMS APPEAR DEFINITE AS CDFNT CROSSES THE AREA. 0-6KM BULK SHEAR LOOKS STRONG AROUND 40-KT AND CAPE VALUES INCREASE TO NEAR 1000 J/KG. MARGINAL RISK FOR SEVERE PER SPC DY2 OTLK APPEARS REASONABLE GIVEN LACK OF DEEP MOISTURE (I.E. DEWPOINTS LESS THAN 60F) AND STRONG INSTABILITY. GUSTY WINDS WOULD BE THE PRIMARY THREAT GIVEN DEEPLY MIXED BDRY LAYER. CDFNT CROSSES THE AREA TUE EVENING WITH SHOWERS AND T-STORMS DIMINISHING. STRATUS CLOUDS FCST TO DEVELOP LATE TUE NIGHT ON NORTHEAST WINDS AS COOL WEDGE DEVELOPS/STRENGTHENS.
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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THE BACK DOOR FRONT WILL SETTLE OVER THE REGION WEDNESDAY AND WEDNESDAY NIGHT WITH ZONAL FLOW ALOFT. PASSING WEAK DISTURBANCES WILL KEEP SHOWERS A POSSIBILITY...ESPECIALLY SOUTHERN PARTS OF THE AREA. TEMPS MAY DEPEND ON FRONTAL POSITION AND AMOUNT OF PRECIP...BUT OVERALL EXPECT BELOW NORMAL DURING THE DAY WITH A MUTED DIURNAL TREND. SFC WAVE OF LOW PRESSURE WILL APPROACH THURSDAY AND INCREASE THE CHANCE FOR SHOWERS AREA-WIDE. WHILE A FEW RUMBLES OF THUNDER COULD OCCUR...THE WEDGE OF STABLE HIGH PRESSURE COULD HELP LIMIT INSTBY. MID/UPPER SHORTWAVE TROUGH WILL NOT PASS THROUGH UNTIL FRIDAY...MAINTAINING SMALLER CHANCES FOR SHOWERS. FRIDAY NIGHT THROUGH SATURDAY NIGHT WILL HAVE A BETTER CHANCE OF BEING DRY AS HIGH PRESSURE BUILDS FROM THE NORTH AND DEEPENING LOW OVER THE PLAINS PROMOTES DOWNSTREAM RIDGING. THE LOW WILL MOVE TOWARD THE MS VALLEY SUNDAY...WITH GOOD MODEL AGREEMENT ON OVERRUNING GULF MOISTURE BRINGING ADDITIONAL RAIN. EXPECT FAIRLY SEASONABLE TEMPS FOR THE LATTER PART OF THE WEEK AND WEEKEND.
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&& .AVIATION /07Z MONDAY THROUGH FRIDAY/...
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LIGHT S TO SW WINDS TODAY STRENGTHENING TUE WITH GUSTS 20-25 KT. SHOWERS AND T-STORMS LIKELY TUE XCPT SCT AT KCHO. CDFNT CROSSES THE AREA TUE EVENING WITH WINDS SHIFTING TO NE. STRATUS CLOUDS FCST TO DEVELOP LATE TUE NIGHT AS WEDGE DEVELOPS. MVFR (PERHAPS LOCALLY IFR) CIGS WILL BE POSSIBLE AT TIMES WEDNESDAY THROUGH FRIDAY AS A FRONT LINGERS OVER THE AREA...ALTHOUGH SPECIFICS ARE UNCERTAIN ATTM. BEST CHANCE FOR RAIN WITH SUB-VFR VSBYS WILL BE THURSDAY.
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&& .MARINE...
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BORDERLINE SCA CONDITIONS THROUGH THIS MORNING. MORE SOLID SCA CONDITIONS TONIGHT AND TUE AS PRES GRADIENT TIGHTENS. T-STORMS LIKELY TUE AFTERNOON WHICH MAY PRODUCE GALE FORCE CONVECTIVE GUSTS AND REQUIRE SPECIAL MARINE WARNINGS. NE TO E WINDS WILL PREVAIL WEDNESDAY THROUGH FRIDAY AS A FRONT LINGERS OVER THE REGION. ATTM IT APPEARS WIND SPEEDS WILL REMAIN BELOW SCA CRITERIA.
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&& .FIRE WEATHER...
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S TO SW WINDS 10 MPH OR LESS STRENGTHENING TO 15 TO 20 MPH TUE. MIN RH`S WILL BE AROUND 30 PERCENT TODAY BUT SOME GUIDANCE LIKE THE ECMWF SUGGESTS LOWER RH`S IN THE 20S. STRONGER WINDS TUE MAY REQUIRE AN SPS FOR THE SOUTHERN HALF IF MOISTURE DOESN`T RECOVER SIGNIFICANTLY.
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&& .TIDES/COASTAL FLOODING...
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WATER LEVELS CONTINUE TO RISE AT ANNAPOLIS AND MAY HIT MINOR COASTAL FLOODING THRESHOLD AT HIGH TIDE AT 8AM TODAY. WILL CONTINUE TO MONITOR CLOSELY.
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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 11 AM EDT THIS MORNING FOR ANZ531>534-537-539>543. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT TUESDAY FOR ANZ530- 531-535-536-538-539. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 PM EDT TUESDAY FOR ANZ532>534-537-540>543.
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&& $$ SYNOPSIS...LFR NEAR TERM...LFR SHORT TERM...LFR LONG TERM...ADS AVIATION...ADS/LFR MARINE...ADS/LFR FIRE WEATHER...LFR TIDES/COASTAL FLOODING...LFR

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