Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 141427 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 927 AM EST SUN DEC 14 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD OVERHEAD THROUGH TONIGHT BEFORE SLOWLY MOVING TO OUR EAST MONDAY THROUGH MONDAY NIGHT. A COLD FRONT WILL PASS THROUGH THE AREA LATER TUESDAY INTO TUESDAY NIGHT AND HIGH PRESSURE WILL RETURN FOR THE WEDNESDAY THROUGH FRIDAY. LOW PRESSURE MAY IMPACT THE AREA NEXT WEEKEND. && .NEAR TERM /THROUGH TONIGHT/...
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SURFACE HIGH PRESSURE STRETCHES ACROSS WEST VIRGINIA...EASTERN KY/TN AND FURTHER SOUTH THIS MORNING. THIS HIGH WILL REMAIN JUST TO OUR WEST TODAY BEFORE BUILDING OVERHEAD TONIGHT. A NORTHWEST FLOW WILL CONTINUE AHEAD OF THIS SYSTEM. MOISTURE ROTATING AROUND THE PERIPHERY OF THE HIGH WILL SPILL INTO THE REGION TODAY. MOST AREAS WILL BE DRY...BUT A BROKEN STRATOCU DECK IS EXPECTED ACROSS THE NORTHEASTERN HALF OF THE CWA. ACROSS CENTRAL VIRGINIA...THERE WILL BE MORE SUNSHINE DUE TO THE DOWNSLOPING FLOW. MID-MORNING TEMPS HAVE JUMPED INTO THE UPPER 40S OVER PORTIONS OF THE FORECAST AREA. 12Z RAOB SHOWS VERY STRONG INVERSION DEVELOPING AT 900MB...WITH MIXING ALREADY TO THIS LEVEL. THIS...ALONG WITH AFOREMENTIONED CLOUD COVER...SHOULD KEEP TEMPS FROM RISING TOO MUCH MORE ACROSS MD...METRO WASHINGTON AND THE MOUNTAINS. SLIGHT ADJUSTMENTS MADE TO MAX TEMP...BUT OVERALL FORECAST STILL RANGES FROM THE MID TO UPPER 30S IN THE ALLEGHENY HIGHLANDS...TO NEAR 50 IN WASHINGTON AND BALTIMORE...TO THE MIDDLE 50S IN CENTRAL VIRGINIA. WINDS NEAR THE TOP OF THE MIXED LAYER AROUND 30-35KTS IN THE 12Z SOUNDING. THESE WINDS WILL MIX DOWN THROUGH THIS AFTERNOON...CAUSING BREEZY CONDITIONS. GUSTS AROUND 25 TO 30 MPH AT THE SURFACE ARE EXPECTED. WINDS WILL QUICKLY DIMINISH AROUND SUNSET TONIGHT DUE TO THE LOSS OF MIXING. HIGH PRESSURE WILL BUILD OVERHEAD...BRINGING DRY CONDITIONS ACROSS MOST AREAS BUT THERE WILL BE SOME MOISTURE TRAPPED UNDERNEATH THE SUBSIDENCE INVERSION. THIS MAY RESULT IN A BKN/OVC STRATOCU DECK...ESPECIALLY ACROSS THE NORTHEASTERN HALF OF THE CWA. FOR LOCATIONS ALONG AND WEST OF THE ALLEGHENY FRONT...THE INCREASED MOISTURE MOVING IN FROM THE NORTH AND WEST WILL CONTINUE TO FLOW OVER THE MOUNTAINS...RESULTING IN LOW CLOUDS/FOG ALONG WITH LIGHT FREEZING RAIN/FREEZING DRIZZLE THIS MORNING. THE FREEZING RAIN ADVISORY CONTINUES FOR THESE AREAS. WEBCAMS IN MOUNT SAVAGE MARYLAND SHOWS THE LOW CLOUDS/FOG ALONG WITH DRIZZLE/LIGHT RAIN. TEMPERATURES FOR THESE LOCATIONS AS WELL AS OTHER LOCATIONS ALONG AND WEST OF THE ALLEGHENY FRONT REMAIN AT OR BELOW FREEZING SO SLIPPERY CONDITIONS ARE EXPECTED. TEMPERATURES WILL WARM UP ABOVE FREEZING LATE THIS MORNING AND AFTERNOON...CAUSING ANY FROZEN PRECIPITATION TO CHANGE TO DRIZZLE/LIGHT RAIN. DRIZZLE AND FOG WILL CONTINUE TONIGHT...BUT TEMPS SHOULD BE JUST ABOVE FREEZING ACROSS MOST LOCATIONS.
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&& .SHORT TERM /MONDAY/... HIGH PRESSURE BOTH AT THE SURFACE AND ALOFT WILL BUILD OVERHEAD MONDAY BEFORE SLOWLY SHIFTING TO THE EAST MONDAY AFTERNOON. DRY AND MILD CONDITIONS ARE EXPECTED ALONG WITH SUNSHINE. MAX TEMPS WILL RANGE FROM THE MID TO UPPER 40S ACROSS NORTHERN MARYLAND TO THE LOWER AND MIDDLE 50S IN DOWNTOWN WASHINGTON/BALTIMORE AS WELL AS CENTRAL VIRGINIA. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... ELONGATED HIGH PRESSURE ALONG THE EASTERN US PUSHES EAST MONDAY NIGHT AHEAD OF APPROACHING LOW PRESSURE SYSTEM PASSING THROUGH THE GREAT LAKES. RIDGE AXIS CROSSES THE REGION LATE MONDAY AS UPPER LVL TROUGH DIPS SOUTH AND PIVOTS EAST. BEGAN MONDAY NIGHT WITH DRY WX...THEN INTRODUCED POPS FOR THE SECOND HALF OF THE NIGHT WITH OVERRIDING PCPN AS A WARM FRONT LIFTS NORTH. BUFKIT SOUNDINGS INDICATING FAIRLY DRY AIR ALOFT...SO COULD AT FIRST SEE A BRIEF PERIOD OF DZ THEN TRANSITIONING TO SCT RAIN SHOWERS WITH A PASSING SHORTWAVE BY 12Z TUES. COLD FRONT SWINGS THROUGH LATE IN THE AREA...WITH INCREASING COVERAGE OF SHOWERS OUT AHEAD OF THE FRONT. 00Z MODEL GUIDANCE GENERALLY AGREEING ON THE COLD FRONT PUSHING OFFSHORE BY 06Z WED. PCPN WILL TAPER OFF OVER EASTERN AREAS...BUT EXPECTING UPSLOPE SNOW SHOWERS AS A WESTERLY FLOW SETS UP IN THE WAKE OF THE FRONT. THIS SET UP WILL CONTINUE THROUGH WED AS SFC HIGH PRESSURE BUILDS EAST AND A NEARLY ZONAL FLOW SETS UP ALOFT. CLOSED LOW ALOFT PERSISTS OVER THE GREAT LAKES...BUT THE MAIN ENERGY LOOKS TO REMAIN NORTH...WITH BUILDING SUBSIDENCE ALONG THE ZONAL FLOW...RESULTING IN DRY WX FOR AREAS OUTSIDE OF THE ALLEGHENY FRONT THRU THURSDAY. WAA AHEAD OF THE COLD FRONT WILL KEEP TEMPS MAINLY ABV FREEZING AND SUCH NOT EXPECTING MUCH IN THE FORM OF WINTRY PCPN TILL THE PCPN IN THE WAKE. GENERALLY USED A GFS/ECMWF BLEND AS BOTH ACCOUNTED FOR THE POTENTIAL FOR SLOWER WARMING TUES OVER NE AREAS AS THE HIGH RETREATS OUT OF THE AREA AND WARMER AIR INJECTION FROM THE WAA OVER SOUTHERN AREAS. LOOKING TO THE END OF THE WEEK...STILL HAVE DIVERGING SOLUTIONS ON THE HANDLING OF A DEVELOPING LOW OVER TEXAS AND ITS PROGRESSION INTO THE WEEKEND. 00Z GFS HAS TRACKED THE LOW FURTHER SOUTH...WITH THE CENTER OF THE LOW MOVING THROUGH THE DELMARVA REGION SATURDAY...WHILE THE ECMWF IS HOLDING ON TO THE COASTAL LOW SOLUTION. THE GFS IS MUCH MORE PROGRESSIVE WITH THE ASSOCIATED SHORTWAVE ENERGY WHILE THE ECMWF DEVELOPS FURTHER SOUTH AND IS SLOW ENOUGH FOR CLOSED LOW FORMATION BEFORE EXITING THE SOUTH. WHILE BOTH SOLUTIONS WOULD BRING WIDESPREAD PCPN TO THE AREA FOR THE WEEKEND...BIG DIFFERENCES EXIST IN TEMPERATURES DEPENDENT UPON THE PATH. AS SUCH...FOR NOW WILL MAINTAIN DRY WX ON FRIDAY...THEN INCREASING POPS FRIDAY NIGHT INTO SATURDAY. WHILE THERE COULD VERY WELL END UP BEING AN AREA THAT SEES A WINTRY MIX OF SNOW...SLEET OR FREEZING RAIN...LOW CONFIDENCE OF TIMING AND LOCATION...AND THUS WILL HOLD WITH JUST RAIN/SNOW MIX FOR THE CWA AT THIS TIME. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... MOISTURE HAS ROTATED AROUND HIGH PRESSURE TO OUR WEST. THIS WILL CAUSE A BKN STRATOCU DECK ACROSS MOST OF THE TERMINALS TODAY INTO TONIGHT. CIGS WILL BE CLOSE TO 3KFT DURING THIS TIME. THE ONE EXCEPTION WILL BE KCHO WHERE VFR CONDITIONS ARE EXPECTED WITH LESS CLOUDS. NORTHWEST WINDS WILL INCREASE LATER THIS MORNING AND AFTERNOON WTIH GUSTS AROUND 20 TO 25 KNOTS. THE WINDS WILL DIMINISH AROUND SUNSET THIS EVENING. VFR CONDITIONS ARE EXPECTED MONDAY WITH HIGH PRESSURE OVERHEAD. GENERALLY VFR CONDITIONS MONDAY NIGHT...WITH DECREASING CONDITIONS AS PCPN MOVES IN. SUB-VFR CONDITIONS LIKELY WITH ANY PCPN TUES. PCPN EXPECTED TO REMAIN RAIN SHOWERS AT THIS TIME. VFR WED WITH WNW WINDS GUSTS UP TO 20 KTS. VFR CONDITIONS LAST THROUGH THE END OF THE WEEK WITH DIMINISHING WINDS AS HIGH PRESSURE BUILDS IN. && .MARINE... HIGH PRESSURE WILL REMAIN TO THE WEST TODAY. GUSTY NORTHWEST WINDS WILL DEVELOP LATER THIS MORNING AND AFTERNOON. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE WATERS. THE SMALL CRAFT ADVISORY CONTINUES TONIGHT FOR THE MARYLAND CHESAPEAKE BAY SOUTH OF POOLES ISLAND TO SMITH POINT AND FOR THE LOWER TIDAL POTOMAC RIVER FROM COBB ISLAND TO SMITH POINT. HIGH PRESSURE WILL BUILD OVER THE WATERS MONDAY. NO MARINE HEADLINES ARE EXPECTED. SUB-SCA CONDITIONS INITIALLY MONDAY NIGHT. WINDS INCREASE BY TUESDAY MORNING AHEAD OF AN APPROACHING COLD FRONT BUT GUSTS ARE EXPECTED TO REMAIN LESS THAN 18 KTS THRU TUES NIGHT. A BRIEF LULL TUES EVENING WITH THE PASSAGE OF THE FRONT...THEN GUSTS INCREASE AGAIN INTO THE 20S AS WINDS SHIFT TO THE WEST BEHIND THE FRONT. SCA CONDITIONS THEN EXPECTED THROUGH WED AND MOST LIKELY THROUGH WED NIGHT BEFORE TAPERING OFF SLOWLY THURSDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST MONDAY FOR ANZ531>534-537- 539>541-543. SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ530- 535-536-538-542. && $$ SYNOPSIS...BJL NEAR TERM...BJL/KCS SHORT TERM...BJL LONG TERM...SEARS AVIATION...BJL/SEARS MARINE...BJL/SEARS

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