Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 261949 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 249 PM EST THU FEB 26 2015 .SYNOPSIS... A COLD FRONT WILL PASS THROUGH THE REGION TONIGHT AND HIGH PRESSURE WILL BUILD OVERHEAD FRIDAY THROUGH SATURDAY. THE HIGH WILL MOVE OFF THE COAST SUNDAY AND ANOTHER COLD FRONT WILL PASS THROUGH THE AREA MONDAY. LOW PRESSURE WILL LIKELY IMPACT THE AREA TUESDAY AND WEDNESDAY OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... LOW PRESSURE MOVING QUICKLY EAST OFFSHORE OF THE DELMARVA THIS AFTERNOON. SOME BREAKS IN THE CLOUDS ARE ALLOWING TEMPS TO POP ABOVE FREEZING. ATTENTION TURNS TO NORTHERN STREAM ENERGY/COLD FRONT WHICH IS NOW PUSHING THROUGH WESTERN PA WITH SOME LIGHT SNOW. FAIRLY GOOD AGREEMENT WITH SOME OF THIS SNOW MAKING IT PAST THE APPALACHIAN CREST LATE THIS AFTERNOON...SPREADING TOWARD THE I-81 CORRIDOR THIS EVENING. HAVE RAISED POPS TO LIKELY ACROSS A LARGER PORTION OF EASTERN WV/WESTERN MD...AND THESE MAY HAVE TO BE ADJUSTED UPWARD FARTHER EAST. HOWEVER...LESS CERTAINTY OF HOW FAR SNOW SHOWERS SURVIVE WITH VARIOUS DEPICTIONS IN QPF/SIM REF FIELDS...THEREFORE DECREASING POPS WITH EASTWARD EXTENT. SHOULD THE SNOW REACH THE METRO AREAS...IT WOULD BE AROUND MIDNIGHT OR SHORTLY THEREAFTER. ACCUMULATIONS WOULD LIKELY BE A HALF INCH OR LESS. AN EXCEPTION IS IN THE UPSLOPE REGIONS WHICH WILL BENEFIT FROM THE COLD MOIST AIRMASS...BUT EVEN THERE CONTRIBUTIONS FROM THE GREAT LAKES ARE LITTLE TO NONE AND WILL LIMIT AMOUNTS. THESE AMOUNTS MAY STILL BE ENOUGH TO COAT ROADS AS TEMPS COOL AFTER SUNSET. SOME SPREAD IN GUIDANCE IN REGARDS TO LOW TEMPS TONIGHT. SNOW PACK...CLOUDS (WHICH SHOULD INCREASE AGAIN WITH THE FRONT)...AND WIND (LIGHT BUT PERHAPS NOT CALM EVERYWHERE) COULD HAVE CONTRIBUTIONS. RAISED SLIGHTLY OVER PREVIOUS FORECAST BUT STILL ON THE COOLER SIDE OF THE ENVELOPE. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... CANADIAN HIGH PRESSURE WILL BUILD TOWARD THE REGION BEHIND A DEPARTING COLD FRONT FOR FRIDAY. NORTHWEST WINDS WILL USHER IN MORE BITTERLY COLD CONDITIONS. A FEW FLURRIES CANNOT BE RULED OUT...BUT THERE SHOULD BE ENOUGH DRY AIR AND SUBSIDENCE AHEAD OF THE HIGH TO PREVENT ANY SNOW ACCUMULATION. MAX TEMPS WILL RANGE FROM THE LOWER TEENS IN THE MOUNTAINS TO THE LOWER AND MIDDLE 30S IN CENTRAL VIRGINIA. THE FORECAST LEANS TOWARD THE COLDER GUIDANCE...DESPITE A DOWNSLOPING FLOW AND SOME SUNSHINE DUE THE STRONG COLD ADVECTION THAT WILL BE TAKING PLACE. HIGH PRESSURE WILL BUILD OVERHEAD FRIDAY NIGHT. MAINLY CLEAR SKIES...LIGHT WINDS AND DRY AIR WILL ALLOW FOR RADIATIONAL COOLING. THEREFORE...FRIDAY NIGHT WILL TURN OUT QUITE COLD. LEANED TOWARD THE COLDER SIDE OF GUIDANCE DUE TO THE RADIATIONAL COOLING. MIN TEMPS WILL RANGE FROM BELOW ZERO IN THE ALLEGHENY HIGHLANDS...TO THE SINGLE DIGITS ACROSS MOST OTHER LOCATIONS...TO THE TEENS IN WASHINGTON AND BALTIMORE. && .LONG TERM /SATURDAY THROUGH THURSDAY/... CANADIAN HIGH PRESSURE WILL REMAIN OVER THE REGION SATURDAY THROUGH SATURDAY NIGHT...BRINGING DRY AND COLD CONDITIONS. HIGH PRESSURE WILL MOVE OFF THE COAST SUNDAY AND A COLD FRONT WILL APPROACH FROM THE WEST. A SOUTHERLY FLOW WILL DEVELOP AHEAD OF THE COLD FRONT...ALLOWING FOR WARM AND MOIST AIR TO OVERRUN THE SURFACE COLD AIR IN PLACE. THIS MAY TRIGGER SOME PRECIPITATION...ESPECIALLY SUNDAY AFTERNOON INTO SUNDAY NIGHT. A WINTRY MIX IS POSSIBLE DURING THIS TIME...BUT CERTAINTY REMAINS LOW. THE COLD FRONT WILL PASS THROUGH LATE SUNDAY NIGHT INTO MONDAY. HIGH PRESSURE WILL BUILD IN BEHIND THIS SYSTEM FOR LATER MONDAY AND MONDAY NIGHT...BRINGING DRY AND CHILLY CONDITIONS. LOW PRESSURE WILL LIKELY IMPACT THE AREA TUESDAY INTO WEDNESDAY. DETAILS REMAIN UNCERTAIN AT THIS TIME...BUT GIVEN THE SYNOPTIC SETUP IT APPEARS THAT WARMER AIR WILL BE DRAWN INTO THIS SYSTEM. THE STRONG SUBTROPICAL RIDGE OVER THE SOUTHEAST CONUS WILL LIKELY CAUSE THE TRACK OF THE LOW TO BE TO OUR WEST. THEREFORE...THE MAIN PTYPE WILL BE RAIN OR A WINTRY MIX CHANGING TO RAIN DEPENDING ON HOW MUCH COLD AIR REMAINS ON THE FRONT SIDE OF THE STORM. THE COLD FRONT WITH THE LOW SHOULD PASS THROUGH WEDNESDAY NIGHT AND HIGH PRESSURE WILL RETURN FOR THE LATTER PORTION OF NEXT WEEK. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... BREAKS IN CLOUD COVER ALLOWING A RETURN TO VFR CONDITIONS THIS AFTERNOON AS LOW PRESSURE MOVES OFFSHORE. CLOUDS WILL INCREASE AGAIN THIS EVENING AHEAD OF A COLD FRONT. CIG HEIGHTS A LITTLE UNCERTAIN BUT MVFR SEEMS REASONABLE. LIGHT SHSN WILL BE POSSIBLE AT ALL THE TERMINALS THIS EVENING INTO TONIGHT...ALTHOUGH MRB HAS THE HIGHEST CHANCE. UNCERTAIN HOW WELL THEY SURVIVE TO THE EAST. HAVE A PERIOD OF MVFR TIMED INTO THE TAFS...ALTHOUGH CANNOT RULE OUT BRIEF IFR. CIGS MAY LINGER THROUGH MUCH OF FRIDAY WITH ABUNDANT LOW LEVEL MOISTURE...BUT THINK THEY WILL EVENTUALLY LIFT INTO VFR RANGE. THERE IS A CHANCE OF FLURRIES FRIDAY AFTERNOON. NW WINDS WILL RANGE FROM 10-20 KT DURING THE DAYLIGHT HOURS. HIGH PRESSURE WILL BUILD OVER THE TERMINALS FRIDAY THROUGH SATURDAY NIGHT...BRINGING VFR CONDITIONS. NORTHWEST WINDS WILL GUST AROUND 15 TO 20 KNOTS FRIDAY. A FEW FLURRIES CANNOT BE RULED OUT FRIDAY...BUT MOST OF THE TIME WILL BE DRY. A COLD FRONT WILL APPROACH THE TERMINALS SUNDAY INTO SUNDAY NIGHT. A PERIOD OF RAIN OR WINTRY PRECIPITATION IS POSSIBLE DURING THIS TIME. HIGH PRESSURE WILL RETURN FOR MONDAY...BUT LOW PRESSURE WILL LIKELY IMPACT THE TERMINALS DURING THE MIDDLE PORTION OF NEXT WEEK. && .MARINE... OCCASIONAL GUSTS TO SCA LEVELS WILL CONTINUE THIS AFTERNOON AS LOW PRESSURE MOVES OFFSHORE. WINDS WILL DIMINISH THIS EVENING. THERE IS A CHANCE OF SNOW SHOWERS AS A COLD FRONT MOVES THROUGH LATE TONIGHT AND SHIFTS WINDS TO THE NW. HIGH PRESSURE WILL BUILD TOWARD THE WATERS FRIDAY BEHIND A DEPARTING COLD FRONT. NORTHWEST WINDS ARE EXPECTED AND A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE WATERS DURING THIS TIME. THE SMALL CRAFT ADVISORY CONTINUES FRIDAY NIGHT FOR THE MARYLAND CHESAPEAKE BAY AND LOWER TIDAL POTOMAC RIVER. HIGH PRESSURE WILL BUILD OVER THE WATERS SATURDAY INTO SATURDAY NIGHT BEFORE MOVING OFF THE COAST SUNDAY. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR PORTIONS OF THE WATERS SUNDAY NIGHT AS A COLD FRONT SWINGS THROUGH. HIGH PRESSURE WILL RETURN FOR MONDAY...BUT LOW PRESSURE WILL LIKELY IMPACT THE WATERS DURING THE MIDDLE PORTION OF NEXT WEEK. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR ANZ530>534-537>543. SMALL CRAFT ADVISORY FROM 9 AM FRIDAY TO 6 AM EST SATURDAY FOR ANZ530>534-537-539>541-543. SMALL CRAFT ADVISORY FROM 9 AM TO 6 PM EST FRIDAY FOR ANZ535- 536-538-542. SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR ANZ535- 536. && $$ SYNOPSIS...BJL/HTS NEAR TERM...ADS SHORT TERM...BJL LONG TERM...BJL AVIATION...BJL/ADS MARINE...BJL/ADS

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