Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 231900 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 300 PM EDT MON MAR 23 2015 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH THIS EVENING. AN UPPER LEVEL DISTURBANCE WILL PASS THROUGH THE AREA LATE TONIGHT AND HIGH PRESSURE WILL RETURN FOR TUESDAY. THE HIGH WILL MOVE OFF THE COAST WEDNESDAY AND A COLD FRONT IS EXPECTED TO PASS THROUGH LATE THURSDAY INTO THURSDAY NIGHT. CANADIAN HIGH PRESSURE WILL RETURN FOR FRIDAY INTO THE WEEKEND. && .NEAR TERM /THROUGH TUESDAY/... SURFACE HIGH PRESSURE REMAINS OVER NEW ENGLAND AND THE RIDGE AXIS EXTENDS SOUTH INTO THE MID-ATLANTIC. AN UPPER-LEVEL DISTURBANCE IS APPROACHING THE AREA FROM THE OHIO VALLEY LATE THIS AFTERNOON. HIGH AND MID-LEVEL CLOUDS WILL INCREASE AHEAD OF THIS SYSTEM LATE THIS AFTERNOON. WILL CONTINUE TO LEAN TOWARD THE WARMER GUIDANCE WITH THE FORECAST FOR MAX TEMPS...BUT TEMPS WILL REMAIN SEVERAL DEGREES BELOW CLIMO. THE UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE REGION LATE TONIGHT. THIS SYSTEM WILL WEAKEN AS IT IS MOVING THROUGH OUR AREA...BUT IT WILL BACK THE LOW-LEVEL FLOW TO THE SOUTHWEST WHICH WILL CAUSE OVERRUNNING. CLOUDS WILL CONTINUE TO INCREASE THIS EVENING AND THERE IS A CHANCE FOR SNOW SHOWERS TO AFFECT THE AREA LATE THIS EVENING AND OVERNIGHT. ACCUMULATING SNOW IS EXPECTED FOR LOCATIONS ALONG AND WEST OF THE ALLEGHENY FRONT WHERE AN UPSLOPE COMPONENT TO THE LOW-LEVEL FLOW WILL ENHANCE THE THREAT FOR SNOW SHOWERS. HOWEVER...SNOW WILL LIKELY COAT THE GROUND FOR SOME AREAS EAST OF THE MOUNTAINS. THE BEST CHANCE FOR A COATING OF SNOW IS ACROSS THE EASTERN PANHANDLE OF WEST VIRGINIA...NORTHERN SHENANDOAH VALLEY AND NORTHERN MARYLAND...INCLUDING THE BALTIMORE METROPOLITAN AREA. ACROSS THESE AREAS...THE LIFT ASSICATED WITH THE UPPER-LEVEL DISTURBANCE HAS THE BEST CHANCE TO COMBINE WITH OVERRUNNING AND GUIDANCE SEEMS TO BE IN GOOD AGREEMENT FOR A PERIOD OF LIGHT SNOW AFTER MIDNIGHT TONIGHT INTO TUESDAY MORNING. LIGHT SNOW OR FLURRIES MAY SPREAD INTO PORTIONS OF THE WASHINGTON METROPOLITAN AREA TUESDAY MORNING...WITH A COATING OF SNOW POSSIBLE. ALTHOUGH THE PRECIPITATION AMOUNTS WILL BE LIGHT...THE TIMING COMBINED WITH THE FACT THAT TEMPERATURES WILL BE BELOW FREEZING SUGGESTS THAT THE MORNING RUSH HOUR MAY BE IMPACTED TUESDAY. FOR OTHER LOCATIONS...MOST AREAS WILL REMAIN DRY BUT A FEW FLURRIES CANNOT BE RULED OUT LATE TONIGHT INTO TUESDAY. THE UPPER-LEVEL DISTURBANCE WILL MOVE AWAY FROM THE AREA LATER TUESDAY MORNING INTO TUESDAY AFTERNOON. MOST AREAS WILL END UP DRY BEHIND THIS SYSTEM...BUT A STRATOCU DECK MAY HANG AROUND FOR SEVERAL HOURS BEFORE DRIER AIR WORKS ITS WAY INTO THE AREA LATE IN THE DAY. MAX TEMPS WILL REMAIN WELL BELOW CLIMO...RANGING FROM THE 30S IN THE MOUNTAINS TO THE MID AND UPPER 40S IN CENTRAL VIRGINIA. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... THE NEXT WEAK UPPER DISTURBANCE WILL CROSS THE REGION LATE TUESDAY NIGHT INTO WEDNESDAY MORNING. HIGH PRESSURE WILL BE TO THE NORTH AND PROVIDE JUST ENOUGH COLD AIR TO INTRODUCE THE POTENTIAL FOR SOME LIGHT IP OR ZR FOR THE FAR N AND W SUBURBS. ELSEWHERE...IT APPEARS TEMPS WILL BE WARM ENOUGH FOR RAIN. HIGH PRESSURE WILL EXIT OFF THE MIDDLE ATLANTIC COAST BY WEDNESDAY AFTERNOON AND WINDS WILL TURN SOUTHERLY. WARMER TEMPERATURES AND HIGHER MOISTURE WILL STREAM NORTH INTO THE FORECAST AREA DURING THE AFTERNOON AND INTO THE NIGHT. WARM AIR ADVECTION PATTERN WILL YIELD A CHANCE FOR RAIN DURING THIS TIME FRAME. TEMPERATURES WEDNESDAY NIGHT MAY NOT FALL OFF THAT MUCH WITH SOUTHERLY FLOW. MOSTLY CLOUDY AND WARM CONDITIONS ARE EXPECTED FOR THE FIRST PART OF THURSDAY. TEMPERATURES ARE EXPECTED TO RIDGE THROUGH THE 60S IN MANY LOCATIONS...EVEN A FEW 70S OVER CENTRAL VA AND SOUTHERN MD. MOISTURE AND INSTABILITY WILL BE IN PLACE AHEAD OF A COLD FRONT THAT WILL SWEEP ACROSS THE REGION THURSDAY NIGHT. SHOWERS AND A FEW THUNDERSTORMS WILL BE POSSIBLE. SOME OF THE STORMS COULD CONTAIN GUSTY WINDS. THE SEVERE THREAT APPEARS MINIMAL AT THIS TIME BUT THE SITUATION WILL NEED TO BE MONITORED. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... COLD FRONT WILL SWEEP ACROSS THE AREA THURSDAY EVENING INTO THE NIGHT. RAIN SHOWERS ARE EXPECTED AS THE FRONT APPROACHES... AND HAVE KEPT A SLGT CHANCE OF THNDRSTMS FOR THE FIRST HALF OF THE NIGHT. ALSO KEPT SLIGHT CHANCE FOR MORE PRECIP POST-FRONTAL. UPPER THROUGH SWEEPS THROUGH THE AREA FRI NIGHT INTO EARLY SAT... SO KEEPING SLIGHT CHNC OF POPS FOR THAT. HIGH PRESSURE BUILDS LATE ON SATURDAY BRINGING COOLER AND DRIER CONDITIONS BEFORE ANOTHER COLD FRONT APPROACHES SUNDAY NIGHT INTO MONDAY. BELOW NORMAL TEMPS ARE EXPECTED FOR FRI NIGHT INTO SAT NIGHT. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... VFR CONDITIONS ARE EXPECTED THROUGH THIS EVENING. AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE AREA LATE TONIGHT INTO TUESDAY MORNING. A PERIOD OF LIGHT SNOW OR FLURRIES IS POSSIBLE...ESPECIALLY ACROSS THE NORTHERN TERMINALS. SUBVFR CIGS AND VSBYS ARE EXPECTED IN ANY SNOW THAT DEVELOPS. VFR TO START TUESDAY NIGHT FOLLOWED BY SUB-VFR CIGS AND VSBYS ALONG WITH A CHANCE FOR MOSTLY RAIN WEDNESDAY MORNING INTO THE NIGHT. SOME LIGHT IP OR ZR MAY BE POSSIBLE FOR AREAS TO THE NORTH AND WEST OF KDCA AND KBWI FOR A SHORT PERIOD WEDNESDAY AM. CIGS WILL LIKELY STAY BKN-OVC MUCH OF WEDNESDAY INTO THURSDAY. A COLD FRONT WILL BRING SHOWERS AND A FEW THUNDERSTORMS THURSDAY AFTERNOON AND EVENING. SOME OF THE STORMS COULD CONTAIN GUSTY WINDS. THE UPPER-LEVEL DISTURBANCE WILL MOVE AWAY FROM THE AREA LATER TUESDAY MORNING...BUT A STRATO CU DECK MAY HANG AROUND FOR MUCH OF THE DAY WITH MVFR CIGS POSSIBLE. A COLD FRONT WILL MOVE THROUGH THURSDAY EVENING/NIGHT...WITH SHRA LIKELY AND A PSBL TSTM INTO FRI. S-SW WINDS WITH SOME PSBL GUSTS 15-20KTS TURNING NW THUR NIGHT. VFR LIKELY FRIDAY WITH NW WINDS FRI. GUSTY CONDITIONS ON SATURDAY. && .MARINE... SURFACE HIGH PRESSURE WILL EXTEND OVER THE WATERS THROUGH TUESDAY. WINDS WILL REMAIN BELOW SCA CRITERIA DURING THIS TIME. SCA CONDITIONS MAY BE POSSIBLE ON THE WATERS WEDNESDAY AND THURSDAY AHEAD OF A COLD FRONT. SOUTHERLY WINDS WILL SHIFT TO WEST LATE THURSDAY NIGHT INTO FRIDAY. EXPECT PERIODS OF RAIN...SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WEDNESDAY INTO THURSDAY. SOME OF THE STORMS COULD CONTAIN GUSTY WINDS THURSDAY AFTERNOON AND EVENING. BETTER CHANCE OF SCA THURSDAY WITH STRONGER S-SW WINDS AHEAD OF A COLD FRONT. SHOWERS AND A PSBL TSTM THURSDAY EVENING INTO THE NIGHT. WINDS SHIFT TO THE NW THUR NIGHT BEHIND THE FRONT. POSS SCA ON SAT WITH INCREASING WINDS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BJL NEAR TERM...BJL SHORT TERM...KRW LONG TERM...IR AVIATION...BJL/IR/KRW MARINE...BJL/IR/KRW

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