Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 280008 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 808 PM EDT SAT SEP 27 2014 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH THE WEEKEND. A LOW PRESSURE SYSTEM WILL FORM OVER THE SOUTHEAST GULF COAST STATES SUNDAY NIGHT...AND MOVE TO THE NORTHEAST TOWARDS THE CAROLINAS MONDAY AND TUESDAY. HIGH PRESSURE WILL BUILD OVER MAINE AND ATLANTIC CANADA IN THE LATTER PART OF THE WEEK. && .NEAR TERM /THROUGH SUNDAY/... HIGH PRESSURE IS IN CONTROL ACROSS THE NORTHEAST AND MID-ATLANTIC THIS EVENING. LIGHT EASTERLY TO CALM WINDS WILL CONTINUE INTO THE OVERNIGHT. OTHER THAN SOME CIRRUS ACROSS THE POTOMAC HIGHLANDS...MOSTLY CLEAR SKIES WILL ALLOW TEMPERATURES TO DROP INTO THE 50S INTO SUNDAY MORNING. PATCHY FOG IS EXPECTED IN LOW LYING AREAS INCLUDING THE SHENANDOAH VALLEY...NRN PIEDMONT AND POTOMAC HIGHLANDS INTO EARLY SUNDAY MORNING. REST OF SUNDAY LOOKS LIKE ANOTHER WINNER OF A DAY IN THE WEATHER DEPARTMENT...PERHAPS A FEW MORE CLOUDS BUT STILL MOSTLY SUNNY WITH MAXIMA WITHIN A COUPLE DEGREES ON EITHER SIDE OF 80 /EXCEPT COOLER OVER THE RIDGE TOPS/. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... RIDGE SHIFTS EAST BY MONDAY. SUNDAY NIGHT WITH BE TRANSITIONAL IN THAT CLOUDS WILL BE ON THE INCREASE ACROSS THE CWA AHEAD OF A SHORTWAVE THAT MAY PRODUCE SOME RAIN MONDAY OR MONDAY NIGHT. UNCERTAINTY STILL EXISTS WITH PLACEMENT/AMOUNTS OF QPF...TRENDED MORE TOWARD ECMWF SOLUTION. && .LONG TERM /TUESDAY THROUGH SATURDAY/... LOW PRESSURE WILL DEVELOP OVER THE SOUTHEASTERN PART OF THE UNITED STATES TUESDAY AND EMERGE OFF THE CAROLINA COAST TUESDAY NIGHT INTO WEDNESDAY. THE ECMWF HAS BEEN CONSISTENTLY MORE AMPLIFIED THAN THE OPERATIONAL GFS...WITH THE LATEST RUN OF THE ECMWF (00Z RUN FROM THE 27TH) CUTTING OFF LOW PRESSURE OFF THE NEW JERSEY COAST WEDNESDAY INTO THURSDAY. THE 12Z GFS MEANWHILE HAS MULTIPLE WEAKER WAVES OF LOW PRESSURE RIDING ALONG A FRONT MUCH FURTHER SOUTH. ALTHOUGH THERE IS A FAIR AMOUNT OF SPREAD...THE GEFS MEAN LIES SOMEWHERE IN BETWEEN AND APPEARS TO OFFER THE BEST MIDDLE-OF-THE-ROAD APPROACH AT THIS POINT. THERE IS A MODERATE LEVEL OF UNCERTAINTY IN THE FORECAST WEDNESDAY AND WEDNESDAY NIGHT AS MODELS DIFFER ON HOW QUICKLY LOW PRESSURE PULLS AWAY FROM THE REGION. HIGH PRESSURE THEN BUILDS IN BRIEFLY FOR THURSDAY. UNCERTAINTY INCREASES MARKEDLY BY THE END OF THE WEEK AS AN AMPLIFYING UPPER-LEVEL TROUGH APPROACHES THE EAST COAST. THE STRENGTH OF THIS TROUGH WILL BE DETERMINED BY ANOTHER /UNRELATED/ STORM THAT IS CURRENTLY ON THE OTHER SIDE OF THE WORLD. THAT STORM WILL HAVE A RIPPLE EFFECT ON THE JET STREAM...BUT JUST HOW STRONG THE RIPPLE EFFECTING OUR REGION WILL BE AT THE END OF NEXT WEEK REMAINS TO BE SEEN. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... JUST A FEW FLAT CU OUT THERE THIS AFTERNOON...OTHERWISE VFR THROUGH THIS EVENING. POTENTIAL EXISTS FOR AFTER MIDNIGHT FOG...MAINLY CHO/MRB BUT CAN/T RULE OUT MVFR AT IAD EITHER. AFTER FOG BURNS OFF...NO PROBLEMS THE REST OF SUNDAY. SUB-VFR IN LOW CIGS/RA PSBL TUE-WED. WINDS GENERALLY E OR NE 10-20 KTS. MODERATE UNCERTAINTY DUE TO DISAGREEMENT W/ STRENGTH AND TIMING OF LOW PRES IMPACTING THE AREA DURING THIS TIME. && .MARINE... NORTHEAST WINDS CONTINUE 10 KT OR LESS THIS AFTERNOON WITH HIGH PRESSURE TO THE NORTH. RIDGE PUSHES EAST LATE SUNDAY...ALLOWING WINDS TO BECOME S/SE BUT SPEEDS EXPECT TO STAY BELOW SCA CRITERIA INTO EARLY NEXT WEEK. REDUCED VISIBILITIES AND WINDS BREACHING SMALL CRAFT ADVISORY CRITERIA ARE POSSIBLE FOR A TIME TUESDAY INTO WEDNESDAY AS LOW PRESSURE DRIFTS UP THE COAST. THE STRENGTH AND TRACK OF THIS LOW DIFFER SUBSTANTIALLY FROM MODEL TO MODEL...WITH THE ECMWF BEING THE MOST AMPLIFIED AND MOST CONSISTENT. BEST CHANCE FOR INCLEMENT WEATHER APPEARS TO BE DURING THE DAY TUESDAY...WITH SLOWLY IMPROVING CONDITIONS THROUGH MID-WEEK. && .TIDES/COASTAL FLOODING... HIGH PRESSURE OVER HEAD HAS LED TO LIGHT TO CALM WINDS ACROSS THE WATERS. THIS HAS ALLOWED ANOMALIES TO DROP TO BELOW MINOR FLOOD THRESHOLDS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BPP/DFH NEAR TERM...BPP/HAS SHORT TERM...BPP LONG TERM...DFH AVIATION...BPP/DFH MARINE...BPP/DFH TIDES/COASTAL FLOODING...

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