Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 111900 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 300 PM EDT FRI JUL 11 2014 .SYNOPSIS... HIGH PRESSURE CENTERED OVER NEW YORK STATE WILL SHIFT OFFSHORE TONIGHT AND SET UP A RETURN FLOW INTO NEXT WEEK. A COLD FRONT WILL CROSS THE AREA EARLY NEXT WEEK. AN UPPER LEVEL LOW WILL THEN PERSIST OVER THE EASTERN STATES INTO LATE NEXT WEEK. && .NEAR TERM /THROUGH SATURDAY/... AS OF 18Z...1025 MB SFC HIGH CENTERED OVER ITHACA NY WITH LIGHT NLY OR ELY FLOW OVER THE AREA. MORE STABLE MARINE AREA AS WELL AS AN EARLIER LAYER OF LOW OVER THE SHENANDOAH VALLEY HAS LIMITED TEMPERATURES AND INSTABILITY TODAY. THAT SAID...A ROBUST CU FIELD HAS BROKEN OUT...THOUGH NO ORGANIZED DEVELOPMENT IS APPARENT IN VISIBLE SATELLITE IMAGERY. WITH 1000 J/KG ESTIMATED FROM A MODIFIED 12Z KIAD RAOB AND VERY LOW SHEAR...ANY THUNDERSTORM ACTIVITY LOOKS TO BE ISOLATED LATE THIS AFTERNOON WITH ANYTHING THAT DEVELOPS PERSISTING INTO THE EVENING. TONIGHT...RETURN FLOW AS HIGH PRESSURE MOVES OFFSHORE. THE INCREASING MOISTURE WILL COUNTER THE CLEAR SKIES A LITTLE...BUT STILL ALLOW MIN TEMPS IN THE MID 60S INLAND...LOW 70S URBAN/NEAR SHORE. ANY ONGOING THUNDERSTORMS SHOULD END AROUND MIDNIGHT WITH NO REAL LLJ TO PROVIDE MOISTURE AND ENERGY. FOG LIKELY DEVELOPS AGAIN LATE TONIGHT IN PRONE VALLEYS AND PLAINS. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... THIS WEEKEND...WARMING TREND WITH CHANCES FOR AFTERNOON CONVECTION (MAINLY BLUE RIDGE AND WEST). OTHERWISE...TYPICAL SUMMERTIME WEATHER WITH MAX TEMPS IN THE UPR 80S SATURDAY...LOW 90S SUNDAY. MIN TEMPS INCREASE A FEW DEGREES EACH NIGHT. && .LONG TERM /MONDAY THROUGH FRIDAY/... MONDAY AFTERNOON AND TUESDAY LOOK TO BE QUITE UNSETTLED. AN ANOMALOUSLY STRONG UPPER LEVEL TROUGH...FOR THIS TIME OF YEAR...WILL WORK ITS WAY ACROSS THE GREAT LAKES REGION THROUGH THE BEGINNING OF NEXT WORKWEEK. CURRENTLY LOOKING LIKE WE WILL HAVE ALL OF THE INGREDIENTS IN PLACE FOR SEVERE WEATHER TUESDAY. THE MID-ATLANTIC WILL BE LOCATED UNDER THE RIGHT ENTRANCE REGION OF AN UPPER LEVEL JET MAX MONDAY NIGHT AND TUESDAY...WHICH WILL LEAD TO ENHANCED DESTABILIZATION. A COLD FRONT WILL BE APPROACHING FROM THE WEST...WHICH WILL SERVE AS A STRONG FORCING MECHANISM FOR ORGANIZED CONVECTION...THOUGH CONVECTIVE INITIATION VIA OTHER MEANS...SUCH AS TERRAIN CIRCULATIONS...REMNANT OUTFLOW BOUNDARIES...AND SEA BREEZES...IS POSSIBLE AS WELL. 0-6 KM SHEAR VALUES NEAR 50 KTS SHOULD ENSURE CONVECTION REMAINS ORGANIZED AS WELL. THE COMBINATION OF THESE INGREDIENTS HAS LED SPC HAS PUT MUCH OF OUR AREA IN THE DAY 4 SEVERE WEATHER OUTLOOK. POPS WILL BE CONFINED TO THE EASTERN PORTION OF THE AREA WEDNESDAY AS HIGH PRESSURE WILL BEGIN RIDGING INTO THE AREA. THIS HIGH WILL REMAIN CENTERED OVER THE GREAT LAKES THROUGH THE MIDDLE OF THE WORKWEEK. THIS WILL BRING A SEASONABLY COOL CONTINENTAL AIR MASS OVER THE AREA WEDNESDAY AND THURSDAY...WITH HIGHS NEAR 80 AND DRY CONDITIONS ACROSS THE AREA. BERMUDA HIGH PRESSURE WILL REGAIN CONTROL AS THE HIGH OVER THE GREAT LAKES WEAKENS TOWARD THE END OF THE WORKWEEK. THIS WILL BEGIN TO USHER SLIGHTLY WARMER AND MORE HUMID AIR INTO THE REGION...AND RETURN THE CHANCE OF THUNDERSTORMS FRIDAY AFTERNOON. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... VFR CONDS THROUGH THIS EVENING ASIDE FROM ISO TSRA. FOG LIKELY DEVELOPS AGAIN TONIGHT IN PRONE AREAS...IFR POSSIBLE AT KMRB AND KCHO (PROBABLY JUST GROUND FOG AT KIAD). VFR PREVAILS THIS WEEKEND WITH CHANCES FOR AFTERNOON THUNDERSTORMS WEST OF THE BLUE RIDGE. && .MARINE... VARIABLE 5-10KT FLOW WITH A BAY BREEZE INTO THIS EVENING. 10 KT RETURN FLOW BEGINS TONIGHT AS HIGH PRESSURE OVER THE UPR MID-ATLANTIC SHIFTS OFFSHORE TONIGHT. SLY FLOW CHANNELS LATE SATURDAY AFTERNOON/THROUGH SATURDAY NIGHT WITH GUSTS IN THE 20 KT RANGE. SCA UP FROM 4PM SATURDAY TO 6AM SUNDAY...AND MAY NEED TO BE EXTENDED INTO SUNDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 PM SATURDAY TO 6 AM EDT SUNDAY FOR ANZ531-539>541. SMALL CRAFT ADVISORY FROM 4 PM SATURDAY TO 6 AM EDT SUNDAY FOR ANZ532>534-537-543. && $$ SYNOPSIS...BAJ NEAR TERM...BAJ SHORT TERM...BAJ LONG TERM...CEB AVIATION...BAJ/CEB MARINE...BAJ/CEB

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