Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 221441 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1041 AM EDT MON SEP 22 2014 .SYNOPSIS... CONTINENTAL HIGH PRESSURE WILL BUILD OVER THE AREA INTO TONIGHT AND PERSIST OVER NEW ENGLAND THROUGH MIDWEEK. A CUT OFF UPPER LEVEL LOW PRESSURE SYSTEM WILL SETTLE NEAR THE SOUTHERN ATLANTIC COAST INTO MID- WEEK...POSSIBLY DRIFTING UP THE COAST AND INTO OUR AREA WEDNESDAY NIGHT INTO FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 14Z...NWLY GUSTS HAVE RESUMED WITH PEAK WINDS AROUND 30 MPH. THESE WILL SLOWLY EASE THROUGH THE AFTERNOON WITH GUSTS ENDING BY SUNSET. UPSLOPE FLOW WILL CONTINUE TO BRING SPRINKLES TO THE ALLEGHENIES WITH DOWNSLOPING FLOW SCATTERING OUT THE THE CEILING EAST OF THERE. COLD AIR ADVECTION WILL LIMIT FURTHER WARMING TODAY TO ONLY A FEW DEGREES MORE...LOW TO MID 70S MAX TEMPS EXPECTED. HIGH PRESSURE CROSSES PITTSBURGH TONIGHT. CALM AND CLEAR CONDITIONS IN THE ALLEGHENIES SHOULD ALLOW TEMPERATURES TO DROP INTO THE 30S IN VALLEYS WEST OF THE SHENANDOAH VALLEY. WILL DECIDE IF A FROST ADVISORY IS NEEDED FOR THE 130PM UPDATE. MIN TEMPS CHILLY ELSEWHERE...LOW TO MID 40S SHENANDOAH VALLEY AND MD/VA PIEDMONT...UPR 40S INLAND COASTAL PLAINS...AND LOW TO MID 50S URBAN/NEAR SHORE. MID 50S AT DCA WOULD MAKE FOR THE COOLEST NIGHT SINCE MAY 19 WHEN IT HIT 49F. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... TUESDAY...CONDITIONS WILL BE EVEN MORE PLEASANT AS WINDS DROP OFF WHILE HIGH PRESSURE SETTLES IN. CLEAR SKIES AND TEMPS BARELY ABOVE 70F W/ A LIGHT NLY BREEZE...WHILE THE JET STREAM RETREATS BRIEFLY TO THE NORTH AND A CUT-OFF UPPER LOW HANGS OUT OFF THE CAROLINA COAST. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... HIGH PRESSURE WILL BE CENTERED OVER NORTHERN NEW ENGLAND AND WILL KEEP THE MIDDLE ATLANTIC IN A WEDGE OF COOLER AIR WITH ONSHORE FLOW WEDNESDAY INTO THURSDAY. AS THE HIGH WEAKENS AND BECOMES MORE ELONGATED...THERE IS SOME POTENTIAL FOR AN UPPER LEVEL CUTOFF LOW/TROUGH TO SWING OFF THE SOUTHEAST U.S COAST AND AID IN THE DEVELOPMENT OF A WEAK SURFACE LOW OFF THE CAROLINAS THURSDAY INTO FRIDAY. THERE IS MUCH UNCERTAINTY BETWEEN THE GFS WHICH KEEPS THE HIGH A BIT STRONGER AND SUPPRESSES MOISTURE TO THE SOUTH AND THE ECMWF WHICH IS WEAKER WITH THE HIGH AND FURTHER NORTH WITH THE MOISTURE. THE NORTHWARD EXTENT OF THE RAINFALL WILL BE DEPENDENT ON HOW STRONG THE HIGH IS AND ITS PLACEMENT. ATTM...CONTINUED TO SIDE TOWARD THE GFS AND KEPT CHANCE POPS RELEGATED TO THE SOUTHERN PORTION OF THE LWX CWFA. CLOUD COVER AND ONSHORE WIND COMPONENT WILL KEEP HIGHS GENERALLY IN THE 70S WITH LOWS IN THE 40S AND 50S. HIGH PRESSURE IS PROGGED TO RESTRENGTHEN FRIDAY THROUGH SUNDAY WITH PLEASANT CONDITIONS EXPECTED ACROSS THE REGION. TEMPERATURES NEXT WEEKEND MAY CLIMB BACK INTO THE UPPER 70S TO NEAR 80 DEGREES FOR THE FIRST WEEKEND OF FALL. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... NW WINDS OF 15-25KT THROUGH MIDDAY...EASING THROUGH THE AFTERNOON. MOUNTAIN WAVE CLOUDS LESSEN THROUGH THE AFTERNOON TOO. GUSTS WILL QUICKLY DROP OFF AFTER SUNSET TONIGHT. VFR CONDS AND LIGHT NLY FLOW TONIGHT THROUGH TUE. MAINLY VFR CONDITIONS EXPECTED WEDNESDAY INTO THURSDAY. THERE IS SOME POTENTIAL FOR LOWER CEILINGS AND SOME LIGHT RAIN OR SHOWERS THURSDAY INTO FRIDAY ESPECIALLY FROM KBWI TO KDCA TO KCHO AND POINTS SOUTH. VFR CONDITIONS ARE EXPECTED OVER THE WEEKEND. && .MARINE... NWLY FLOW GUSTING 20 TO 25 KT THROUGH MIDDAY...EASING THROUGH THE AFTERNOON. SCA FOR ALL WATERS UNTIL 6PM. LIGHT NLY FLOW TONIGHT THROUGH TUESDAY WITH HIGH PRESSURE CENTERED TO THE NORTH. A PERSISTENT ONSHORE FLOW WILL DEVELOP LATER WEDNESDAY AND PERSIST INTO THURSDAY OR FRIDAY. SMALL CRAFT CONDITIONS MAY BE POSSIBLE FOR A PORTION OF THE WATERS DURING THIS TIME FRAME. WINDS WILL REMAIN BELOW SCA LEVELS AS HIGH PRESSURE BUILDS OVER THE MIDDLE ATLANTIC NEXT WEEKEND. && .TIDES/COASTAL FLOODING... A PERSISTENT ONSHORE FLOW IS EXPECTED TO DEVELOP WEDNESDAY. THIS WILL LEAD TO HIGHER THAN NORMAL WATER LEVELS PARTICULARLY OVER THE WESTERN SHORE OF THE CHESAPEAKE BAY. MINOR TIDAL INUNDATION IS POSSIBLE DURING HIGH TIDE STARTING WEDNESDAY NIGHT. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ530>543. && $$ SYNOPSIS...BAJ/GMS NEAR TERM...BAJ/GMS SHORT TERM...GMS LONG TERM...KRW AVIATION...BAJ/GMS/KRW MARINE...BAJ/GMS/KRW TIDES/COASTAL FLOODING...LWX

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