Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 191800 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 100 PM EST FRI DEC 19 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD OVERHEAD THIS AFTERNOON...THEN PERSIST THROUGH SUNDAY. LOW PRESSURE WILL TRACK UP THE MID-ATLANTIC COAST MONDAY THROUGH MONDAY NIGHT. A STRONG COLD FRONT WILL PASS THROUGH THE AREA WEDNESDAY. && .NEAR TERM /THROUGH SATURDAY/... SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD TOWARD THE REGION FROM THE OHIO VALLEY THIS AFTERNOON. A NORTHWEST FLOW AHEAD OF THE HIGH WILL CAUSE SEASONABLY CHILLY CONDITIONS DURING THIS TIME. THERE WILL BE JUST ENOUGH MOISTURE UNDERNEATH THE SUBSIDENCE INVERSION FOR A BKN STRATOCU DECK ACROSS THE NORTHERN AND CENTRAL PORTIONS OF THE CWA. FURTHER SOUTH ACROSS CENTRAL VIRGINIA...PLENTY OF SUNSHINE IS EXPECTED DUE TO THE DOWNSLOPING NORTHWEST FLOW. HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT. THE STRATO CU DECK SHOULD BREAK ACROSS MOST AREAS THIS EVENING...BUT HIGH AND MID- LEVEL CLOUDS WILL INCREASE FROM SOUTHWEST TO NORTHEAST LATER TONIGHT AS AN UPPER-LEVEL DISTURBANCE APPROACHES FROM THE TENNESSEE VALLEY. MIN TEMPS WILL RANGE FROM THE LOWER 20S IN THE MOUNTAINS TO THE LOWER AND MIDDLE 30S IN DOWNTOWN WASHINGTON AND BALTIMORE. THE UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE REGION SATURDAY. THIS WILL CAUSE SURFACE LOW PRESSURE TO DEVELOP OFF THE SOUTH CAROLINA COAST...BUT IT WILL BE TOO FAR TO OUR SOUTH FOR ANY PRECIPITATION. HOWEVER...MOSTLY CLOUDY SKIES ARE EXPECTED AS HIGH AND MID-LEVEL CLOUDS PASS THROUGH WITH THE UPPER-LEVEL DISTURBANCE. SEASONABLY CHILLY CONDITIONS WILL CONTINUE BUT WINDS WILL BE LIGHT. MAX TEMPS WILL RANGE FROM THE UPPER 20S AND LOWER 30S IN THE ALLEGHENY HIGHLANDS TO THE LOWER AND MIDDLE 40S IN CENTRAL VIRGINIA. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... LARGE SURFACE HIGH PRESSURE WILL EXTEND FROM SOUTHEASTERN CANADA THROUGH THE MIDDLE ATLANTIC AND INTO THE SOUTHEASTERN CONUS SATURDAY NIGHT. A WEAK UPPER TROUGH WILL MOVE THROUGH THE AREA...RESULTING IN A MID-LEVEL CLOUD DECK OVER THE AREA. GIVEN THE CLOUD COVER...FAVORED THE WARMER MET GUIDANCE FOR LOW TEMPS. IT WILL BE A COLD NIGHT...WITH LOWS IN THE 20S OVER NEARLY ALL OF THE FORECAST AREA. DOWNTOWN AREAS OF BALTIMORE AND WASHINGTON MAY STAY AT OR JUST ABOVE FREEZING OVERNIGHT. THE HIGH WILL BE DIRECTLY OVERHEAD SUNDAY...WITH MOSTLY SUNNY SKIES AND LIGHT WINDS. SOME DISCREPANCY AMONG MODELS AS TO WHETHER THE RIDGE AXIS WILL MAKE IT TO THE DELMARVA BY THE AFTERNOON...WHICH WOULD RESULT IN LIGHT RETURN FLOW ACROSS THE SOUTHERN AND WESTERN COUNTIES OF THE CWA. HIGH EXPECTED TO BE IN THE MID TO UPPER 40S ACROSS MOST OF THE CWA...WITH LOW 40S POSSIBLE NEAR THE MASON DIXON LINE AND IN HIGHER ELEVATIONS. ONLY GRADUAL EWD MOVEMENT IN THE RIDGE AXIS TOWARDS THE COAST SUNDAY NIGHT. MODELS HAVE TRENDED SLOWER IN THE DEVELOPMENT OF LOW PRESSURE ALONG THE SOUTHEAST COAST. REMOVED ALL POPS FROM THE CWA SUNDAY NIGHT ACCORDINGLY. LOWS WILL BE SIMILAR TO SATURDAY NIGHT...IN THE 20S FOR MOST OF THE CWA AND A FEW SPOTS ABOVE 30 IN METRO BALTIMORE/WASHINGTON. && .LONG TERM /MONDAY THROUGH FRIDAY/... PVA MAX IN SOUTHERN FLOW WILL SUPPORT WIDESPREAD PRECIPITATION ACROSS REGION MONDAY. ALTHOUGH MOST OF PRECIPITATION LOOKS TO LIQUID IT APPEARS THAT ENOUGH COLD AIR IS IN PLACE FOR PRECIPITATION BEGIN AS A WINTRY MIX EARLY MONDAY. STRONG COLD FRONT SUPPORTED BY UPPER LEVEL CUT-OFF SOUTH OF THE GREAT LAKES WILL CROSS THE MID ATLANTIC STATES BY WEDNESDAY. RAIN WILL CHANGE OVER TO SNOW IN AREA AFFECTED BY MUCH COLDER AIR STREAMING INTO REGION BEHIND THE LOW. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... A BKN STRATOCU DECK IS EXPECTED ACROSS MOST OF THE TERMINALS THROUGH THIS AFTERNOON. CIGS SHOULD REMAIN ABOVE 3KFT. NORTHWEST WINDS WILL GUST AROUND 15 TO 20 KNOTS THROUGH THIS AFTERNOON BEFORE DIMINISHING AROUND SUNSET. HIGH PRESSURE WILL BUILD OVER THE TERMINALS TONIGHT THROUGH SATURDAY. VFR CONDITIONS WILL CONTINUE. HIGH PRESSURE WILL BE DIRECTLY OVERHEAD SATURDAY NIGHT THROUGH SUNDAY NIGHT. VFR CONDITIONS EXPECTED WITH LIGHT WINDS. LOW PRESSURE MAY BRING PRECIPITATION AND SUBVFR CONDITIONS MONDAY AND TUESDAY. A STRONG COLD MAY IMPACT THE TERMINALS WEDNESDAY. && .MARINE... NW WINDS WILL CONTINUE TODAY AS HIGH PRESSURE APPROACHES FROM THE WEST. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE WATERS DURING THIS TIME. HIGH PRESSURE WILL BUILD OVER THE TONIGHT THROUGH SATURDAY. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THIS EVENING ACROSS THE MARYLAND CHESAPEAKE BAY FROM SANDY POINT TO SMITH POINT AND THE LOWER TIDAL POTOMAC RIVER FROM COBB ISLAND TO SMITH POINT. HIGH PRESSURE WILL BE DIRECTLY OVER THE WATERS SATURDAY NIGHT THROUGH SUNDAY NIGHT. LIGHT NORTHERLY FLOW SATURDAY NIGHT AND SUNDAY...SHIFTING TO THE E-NE SUNDAY NIGHT. LOW PRESSURE MAY IMPACT THE WATERS MONDAY INTO TUESDAY BEFORE A STRONG COLD FRONT PASSES THROUGH WEDNESDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR ANZ530- 531-535-536-538-539-542. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR ANZ532>534- 537-540-541-543. && $$ SYNOPSIS...BJL NEAR TERM...BJL SHORT TERM...KS LONG TERM...CEM AVIATION...BJL/KS MARINE...BJL/KS

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