Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 251037 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 637 AM EDT WED MAR 25 2015 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO DRIFT OFF THE ATLANTIC COAST TODAY. A COLD FRONT WILL PASS THROUGH THE AREA LATE THURSDAY INTO FRIDAY. CANADIAN HIGH PRESSURE WILL RETURN FOR FRIDAY INTO THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... HEADLINE UPDATE...THE FREEZING RAIN ADVISORY HAS BEEN EXPANDED NORTH AND EAST AND NOW INCLUDES THE BALTIMORE AND WASHINGTON METRO AREAS. RADAR TRENDS SHOW A CONTINUED TRAJECTORY OF BLOSSOMING PRECIP ALONG/AHEAD OF AN APPROACHING WARM FRONTAL BOUNDARY. TEMPS STILL BELOW FREEZING... BY A FEW DEGREES IN SOME OF THE NEW ADVISORY AREA. PREV DISC... HIGH PRESSURE IS WEDGED ACROSS THE MID-ATLANTIC WHILE CLEAR SKIES HAVE LED TO TEMPS DROPPING INTO THE 20S ACROSS MUCH OF THE AREA. WARM AIR ADVECTION ALOFT HAS LED TO OVERRUNNING AND A BAND OF LIGHT PRECIPITATION EXTENDS FROM S MI TO CENTRAL VA THIS MORNING. PRECIPITATION HAS BLOSSOMED ACROSS WV OVERNIGHT AND WILL CONTINUE TO LIFT NORTHEAST INTO THE ALLEGHENY HIGHLANDS THIS MORNING. LIGHT FREEZING RAIN IS EXPECTED ACROSS PORTIONS OF THE BLUE RIDGE MTNS...SHENANDOAH VALLEY AND POTOMAC HIGHLANDS. LIGHT FREEZING RAIN WILL LEAD TO TRACE TO A FEW HUNDREDTHS OF AN INCH OF ACCUMULATION THIS MORNING. THE HRRR AND WRFARW HAVE BEEN PERSISTENT ALL NIGHT BRINGING PRECIPITATION INTO THE REGION. QUESTION EXISTS HOW FAR EAST THE PRECIPITATION WILL TRAVEL BEFORE TEMPS RISE ABOVE FREEZING THIS MORNING. WILL BE MONITORING SFC TEMPS AND RADAR AND EXTENSION MAY BE NEEDED FURTHER NORTH AND EAST. HIGH PRESSURE WILL STAY WEDGED ACROSS THE REGION THROUGH THE AFTERNOON. SOUTHERLY FLOW WILL ALLOW TEMPS TO RISE INTO THE 40S BUT AREAS ACROSS THE HIGHLANDS WILL LIKELY REACH THE UPPER 50S TODAY AS A WARM FRONT MOVES THROUGH. THE WEDGE WILL KEEP EAST OF THE BLUE RIDGE IN LOW CLOUDS THROUGH THE DAY. LIGHT RAIN IS POSSIBLE ACROSS THE REGION TODAY AS WARM AIR ADVECTION CONTINUES. HIGH PRESSURE WILL MOVE OFF THE COAST WEDNESDAY NIGHT AND LIGHT SOUTHERLY FLOW IS EXPECTED. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... A BULK OF THE DAY THU LOOKS RELATIVELY WARM/DRY...ALBEIT W/ A LARGE WAA REGION OVERHEAD DURING THAT TIME. VERY LIGHT AND POORLY ORGANIZED SHOWERS CAN CERTAINLY DEVELOP ANYWHERE IN SUCH A REGION BUT MUCH OF THE ACTIVITY FOR THU MAY ACTUALLY OCCUR EARLY AND AGAIN LATE IN THE DAY. TO START THE DAY...ROUNDING THE OUTER REACHES OF AN OFFSHORE HIGH...SCATTERED SHOWERS WILL SLIDE ACROSS PORTIONS OF THE AREA FROM SW-TO-NE COINCIDENT W/ A LOW LEVEL JET MAX. AS THIS FEATURE GETS BUMPED OFF THE COAST...SOME SINKING AIR...DEPARTING CLOUDS AND WARMING TEMPS SHOULD BE MORE COMMON HEADING INTO THE LATE MRNG/AFTN HRS. MEANWHILE...TWO SEPARATE PIECES OF AN INTENSIFYING AND SYSTEM TO OUR WEST WILL APPROACH FROM THE LOWER OHIO/TENN RVR VLY. THIS FIRST FEATURE WILL BE A LOW PRES SYSTEM SLIDING OVER THE OHIO VLY AND EVENTUALLY OFF TO OUR NORTH...STAYING NORTH AND ALLOWING WARM AIR TO CONTINUE BUILDING INTO THE REGION DURING THE AFTN/EVE. A DEEPENING UPPER WAVE WELL WEST OF THIS ACTIVITY WILL DIVE DOWN FROM THE NRN MS VLY AND STRENGTHEN THE PRECIP ACROSS AREAS JUST AFFECTED BY THE FIRST FEATURE. THIS PIECE OF ENERGY WILL THEN MAKE ITS WAY ACROSS THE APLCNS LATER THAT EVE...NOT EXPECTED TO MOVE ACROSS OUR REGION UNTIL FRI. THE POTENTIAL CONVECTIVE ACTIVITY OUT AHEAD OF THIS DIGGING TROUGH LOOKS TO BE LATE THU NIGHT INTO THE EARLY MRNG HRS FRI. RESIDUAL INSTABILITY MAY BE MARGINAL AT THAT POINT...THOUGH LOW LEVEL STEERING FLOW AND NOCTURNAL JET ACTIVITY MAY MAKE UP FOR IT IN THE WAY OF GUSTY WINDS W/ HEAVIER LOCALIZED DOWNPOURS. WILL KEEP A PERIOD OF LIKELY POPS IN FOR THE OVERNIGHT PERIOD...W/ A SLIGHT REDUCTION IN THE DAYTIME POPS FOR THU. FRI WILL BE ANOTHER USHERING-IN OF CAA W/ DRIER AIR AND OCCASIONALLY BREEZY NW WINDS. A NOTICEABLE TEMP DROP WILL OCCUR FROM THU GOING INTO FRI W/ THE COLD FRONT PASSING THRU...AS TEMPS DROP FROM THE 70S THU AFTN TO THE 40S OVERNIGHT. MAX TEMPS BARELY REACH THE 50 DEG MARK ON FRI...W/ LOWS FRI NIGHT BACK TOWARD THE FREEZING MARK. SOME SCATTERED RAIN SHOWERS AND POSSIBLY SOME BRIEF SNOW MIXING IN W/ THE ISOLATED BATCHES ON FRI W/ THE STRONG PASSAGE OF THE UPPER VORT OVERHEAD. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... AN UPPER-LEVEL TROUGH WILL SWING THROUGH THE AREA FRIDAY NIGHT INTO SATURDAY BEFORE COLD HIGH PRESSURE BUILDS OVERHEAD SATURDAY NIGHT INTO SUNDAY. A NORTHWEST FLOW AHEAD OF THE HIGH WILL USHER IN UNUSUALLY COLD CONDITIONS FOR THIS TIME OF YEAR. THE HIGH WILL MOVE OFF THE COAST LATER SUNDAY AND MILDER CONDITIONS ARE EXPECTED IN THE AFTERNOON DUE TO A RETURN FLOW...BUT TEMPS WILL LIKELY REMAIN BELOW CLIMO. A COLD FRONT WILL PASS THROUGH THE AREA MONDAY...BRINGING A CHANCE FOR SHOWERS. MILDER CONDITIONS ARE EXPECTED WITH A SOUTHWEST FLOW AHEAD OF THE FRONT. HIGH PRESSURE WILL RETURN FOR THE MIDDLE PORTION OF NEXT WEEK. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... A WARM FRONT WILL APPROACH THE REGION TODAY AND CIGS WILL LOWER REACHING MVFR/IFR THIS EVENING. A 40KT LLJ MAY PRODUCE LLWS LATE TONIGHT AND INTO THURSDAY MORNING. MVFR/IFR CIGS ARE EXPECTED TO CONTINUE TONIGHT BEFORE MIXING OUT THURSDAY MORNING. BRIEF MVFR CIGS POSSIBLE...SOME IFR LATE WED NIGHT. SOME IMRVMNT XPCTD THU MRNG INTO THE AFTN...THEN DEGRADING AGAIN LATE IN THE DAY AND OVRNGT AHD OF A CD FNT. RA XPCTD THU AFTN/OVRNGT W/ ISOLD TSTMS PSBL. CONDS SHOULD BEGIN IMPRVG AS WINDS TURN TO THE NW FRI. VFR CONDITIONS ARE EXPECTED THROUGH THE WEEKEND. && .MARINE... S WINDS EXPECTED ON THE WATERS TODAY. HIGH PRESSURE WILL MOVE OFF THE COAST THIS AFTERNOON AND EVENING AND RETURN FLOW WILL ALLOW WINDS TO INCREASE. A SCA IS IN EFFECT FOR THE BAY NORTH OF DRUM POINT. S WINDS WILL CONTINUE TONIGHT AND GUSTS SHOULD SUBSIDE. SCA CONDS XPCTD THU AHD OF A CD FNT...W/ ISOLD TSTMS PSBL...THEN TURNING TO THE NW AFTR MDNGT THU W/ WINDS CONTINUING ABV SCA VALUES INTO FRI MRNG. HIGH PRESSURE WILL BUILD OVER THE WATERS FOR THE WEEKEND. && .TIDES/COASTAL FLOODING... SOUTHERLY WINDS WILL DEVELOP WEDNESDAY AND THE SOUTHERLY FLOW WILL INCREASE AHEAD OF A COLD FRONT THURSDAY. THE INCREASED SOUTHERLY FLOW WILL CAUSE WATER LEVELS TO ELEVATE...AND TIDAL ANOMALIES MAY BE HIGH ENOUGH FOR MINOR FLOODING NEAR TIMES OF HIGH TIDE THURSDAY INTO THURSDAY NIGHT. THE COLD FRONT WILL PASS THROUGH LATER THURSDAY EVENING AND A NORTHWEST FLOW WILL CAUSE WATER LEVELS TO DECREASE LATE THURSDAY NIGHT INTO FRIDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...FREEZING RAIN ADVISORY UNTIL NOON EDT TODAY FOR DCZ001. MD...FREEZING RAIN ADVISORY UNTIL NOON EDT TODAY FOR MDZ003>006-011- 013-014-016>018-501>508. VA...FREEZING RAIN ADVISORY UNTIL NOON EDT TODAY FOR VAZ026>031-040- 051>055-057-501-502-505>508. WV...FREEZING RAIN ADVISORY UNTIL NOON EDT TODAY FOR WVZ050>053-055- 501>506. MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 6 PM EDT THIS EVENING FOR ANZ530>533-538>541. SMALL CRAFT ADVISORY FROM 10 AM TO 6 PM EDT THURSDAY FOR ANZ530>543. && $$ SYNOPSIS... NEAR TERM...HAS SHORT TERM...GMS LONG TERM...GMS AVIATION...HAS/GMS MARINE...HAS/GMS TIDES/COASTAL FLOODING...

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