Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 261930 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 230 PM EST WED NOV 26 2014 .SYNOPSIS...
-- Changed Discussion --
A LOW PRESSURE SYSTEM WILL MOVE AWAY FROM THE AREA TONIGHT. AN UPPER- LEVEL DISTURBANCE WILL PASS THROUGH THE AREA THURSDAY AND HIGH PRESSURE WILL BUILD OVERHEAD FRIDAY. THE HIGH WILL MOVE OFF THE COAST DURING THE WEEKEND.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH THURSDAY/...
-- Changed Discussion --
LOW PRESSURE CONTINUES TO INTENSIFY AS IT MOVES NORTHEAST OFF THE DELMARVA COAST THIS AFTERNOON. A POTENT SHORTWAVE IN THE SOUTHWEST FLOW ALOFT IS MOVING THROUGH THE AREA DURING THIS TIME. THE HEAVIEST PRECIPITATION HAS TAPERED OFF SINCE THE STRONG FORCING FROM THIS SYSTEM HAS PUSHED OFF TO OUR EAST. HOWEVER...BANDS OF MODERATE PRECIPITATION ARE STILL EXPECTED UNTIL LATE AFTERNOON WHEN THE POTENT SHORTWAVE FINALLY MOVES AWAY FROM THE AREA. THE RAIN/SNOW LINE IS NEAR THE I-95 CORRIDOR...BUT THE BULK OF THE ACCUMULATING SNOW HAS BEEN CONFINED TO LOCATIONS NEAR THE MASON-DIXON LINE AND ALSO FOR AREAS NEAR AND WEST OF THE BLUE RIDGE MOUNTAINS. ACROSS THESE AREAS...ADDITIONAL SNOWFALL ACCUMULATIONS AROUND AN INCH OR TWO ARE POSSIBLE. THE WINTER HEADLINES REMAIN IN EFFECT. FARTHER SOUTH AND EAST ACROSS THE NORTHWESTERN SUBURBS OF WASHINGTON AND BALTIMORE...ANY ADDITIONAL SNOW ACCUMULATION WILL BE LESS THAN AN INCH AND CONFINED MAINLY TO GRASSY SURFACES WITH SURFACE TEMPS JUST ABOVE FREEZING. FOR LOCATIONS NEAR AND EAST OF I-95...RAIN MAY MIX WITH SNOW BEFORE ENDING LATE THIS AFTERNOON BUT LITTLE OR NO SNOW ACCUMULATION IS EXPECTED. DRIER AIR WILL MOVE INTO THE AREA FROM THE NORTHWEST TONIGHT AS THE LOW RAPIDLY MOVES OFF TO OUR NORTH AND EAST. TEMPERATURES WILL DROP BELOW FREEZING ACROSS MANY AREAS...CAUSING THE THREAT FOR ANY WET OR SLUSHY ROADS TO FREEZE. ANOTHER UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE REGION LATE TONIGHT THROUGH THURSDAY MORNING. THIS MAY TRIGGER SOME RAIN AND SNOW SHOWERS...ESPECIALLY ACROSS THE ALLEGHENY HIGHLANDS INTO CENTRAL VIRGINIA AND SOUTHERN MARYLAND. TEMPS WILL BE COLD ENOUGH FOR SNOW SHOWERS...BUT THE BEST CHANCE FOR SNOW ACCUMULATION WILL BE FOR LOCATIONS ALONG AND WEST OF THE ALLEGHENY FRONT. EVEN ACROSS THESE AREAS ADDITIONAL SNOWFALL ACCUMULATIONS WILL BE LIGHT. THE UPPER-LEVEL DISTURBANCE WILL MOVE AWAY FROM THE AREA THURSDAY AFTERNOON AND HIGH PRESSURE WILL BUILD TOWARD THE REGION FROM THE OHIO VALLEY. A STRAY RAIN OR SNOW SHOWER CANNOT BE RULED OUT WITH AN UPPER-LEVEL TROUGH OVERHEAD...BUT MOST AREAS WILL BE DRY AND CHILLY WITH SOME SUNSHINE. MAX TEMPS WILL RANGE FROM THE 20S AND LOWER 30S IN THE MOUNTAINS TO THE LOWER AND MIDDLE 40S IN CENTRAL VIRGINIA.
-- End Changed Discussion --
&& .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
-- Changed Discussion --
SFC HIGH PRES CONTINUES TO BUILD EAST OVER THE AREA THROUGH FRIDAY. NWLY FLOW WILL CONTINUE TO CAUSE UPSLOPE SNOW WEST OF THE ALLEGHENY FRONT INTO LATE THURSDAY NIGHT BEFORE TAPERING OFF AS THE SATURATED LAYER DECREASES. SHOULD JUST BE WAVE CLOUDS EAST OF THERE SINCE THE UPR TROUGH AXIS MOVES EAST OF THE AREA THURSDAY EVENING. NWLY FLOW GUSTS PERIODICALLY TO 20 TO 25 MPH THURSDAY NIGHT IN COLD AIR ADVECTION...THEN MIXES DOWN AGAIN ACROSS THE AREA FRIDAY. GRADIENT SLACKENS THROUGH FRIDAY AFTERNOON. FRIDAY NIGHT...SFC HIGH CENTER CROSSES THE AREA WITH CLEAR AND CALM AND MIN TEMPS BACK BELOW FREEZING. PLACES WITH A REMAINING SNOWPACK OF MORE THAN A FEW INCHES (HIGHER ELEVATIONS) WILL SEE A MARKED DROP IN TEMPERATURES...POSSIBLY INTO THE TEENS. LOW 30S ALONG THE SHORE LINE.
-- End Changed Discussion --
&& .LONG TERM /SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
HIGH PRESSURE WILL MOVE OFFSHORE THIS WEEKEND SETTING UP A SOUTHERLY RETURN FLOW. TEMPERATURES WILL RETURN TO NEAR NORMAL UNDER THIS REGIME. A FRONT WILL BUMP INTO THIS HIGH LATE IN THE WEEKEND THEN STALL NEAR THE AREA NEXT WEEK. IT LOOKS WARM ENOUGH FOR RAIN SHOWERS ALONG THIS FRONT MONDAY. HIGH PRESSURE WILL MOVE BY TO THE NORTH BEHIND THE FRONT...BUT DEPENDING ON HOW FAR SOUTH THE FRONT GETS IT MAY NOT GET MUCH COOLER. MODELS DISAGREE ON THIS PLACEMENT SO TEMPERATURE FORECAST IS UNCERTAIN DURING THE MIDDLE OF NEXT WEEK.
-- End Changed Discussion --
&& .AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
IFR CONDITIONS ALONG WITH SNOW AND RAIN WILL GIVE WAY TO MVFR AND VFR CONDITIONS THIS EVENING AS THE PRECIPITATION ENDS. PATCHY BR IS POSSIBLE LATE TONIGHT INTO EARLY THURSDAY. AN UPPER-LEVEL DISTURBANCE MAY BRING A RAIN OR SNOW SHOWER LATE TONIGHT THROUGH THURSDAY...BUT MOST AREAS WILL BE DRY. VFR CONDITIONS WITH NORTHWEST WINDS ARE EXPECTED FOR MOST OF THURSDAY. NWLY FLOW GUSTS 20 TO 25 KT THURSDAY NIGHT AND FRIDAY AS HIGH PRES BUILDS (VFR CONDS). HIGH OVERHEAD FRIDAY NIGHT WITH CONTINUED VFR. MAINLY VFR THROUGH THE WEEKEND W/ WIND BECOMING S AROUND 10 KT.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
LOW PRESSURE WILL INTENSIFY BUT RAPIDLY MOVE OFF TO OUR NORTHEAST TONIGHT. GUSTY NORTHWEST WINDS WILL DIMINISH TONIGHT. A GALE WARNING IS IN EFFECT FOR THE REST OF THIS AFTERNOON FOR THE MARYLAND CHESAPEAKE BAY FROM NORTH BEACH TO SMITH POINT AND THE LOWER TIDAL POTOMAC RIVER FROM COBB ISLAND TO SMITH POINT. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE REST OF THE WATERS. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR PORTIONS OF THE WATERS THROUGH THIS EVENING. NORTHWEST WINDS ARE EXPECTED THURSDAY...BUT SPEEDS SHOULD REMAIN BELOW SCA CRITERIA. SURGE OF NWLY FLOW THURSDAY EVENING WITH 20 TO 25 KT GUSTS OVER MOST OF THE WATERS (SCA FOR ALL BUT UPPER TIDAL POTOMAC...PATAPSCO AND PATUXENT)...THEN ACROSS THE WATERS FRIDAY. WINDS WILL QUICKLY DIMINISH WITH SUNSET AS GRADIENT SLACKENS. HIGH PRESSURE OVERHEAD FRIDAY NIGHT WITH SLY FLOW BEGINNING SATURDAY MORNING. SOUTHERLY FLOW TO SMALL CRAFT ADVISORY LEVELS POSSIBLE AHEAD OF A FRONT OVER THE WEEKEND INTO EARLY NEXT WEEK.
-- End Changed Discussion --
&& .CLIMATE...
-- Changed Discussion --
RECORDS FOR EARLIEST MEASURABLE SNOW ALREADY PASSED A FEW WEEKS AGO...BUT BELOW IS A LIST OF DAILY MAXIMUM SNOWFALL RECORDS SPECIFIC TO THE DATE OF NOVEMBER 26TH. THE SNOWFALL REPORTED AT DULLES SO FAR TODAY HAS BEEN 1.3 INCHES AND THIS BREAKS THE OLD RECORD BELOW OF 1.1 INCHES SET IN 1978. DCA/BWI RECORDS ARE SAFE. DCA 2.2" (1898) BWI 4.5" (1898) IAD 1.1" (1978)
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...NONE. MD...WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR MDZ003>006-501-502. WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR MDZ007- 009>011. VA...WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR VAZ025>031-036>040-042-501-503-504. WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR VAZ050>053-502. WV...WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR WVZ050>053-055-501>506. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR ANZ530>532- 536-538>540-542. SMALL CRAFT ADVISORY FROM 7 PM THURSDAY TO 6 PM EST FRIDAY FOR ANZ530>534-536-537-539>541-543. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EST TONIGHT FOR ANZ533-534-537-541-543. GALE WARNING UNTIL 6 PM EST THIS EVENING FOR ANZ533-534-537- 541-543. SMALL CRAFT ADVISORY FROM 8 AM TO 6 PM EST FRIDAY FOR ANZ535- 538-542. SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ535.
-- End Changed Discussion --
&& $$ SYNOPSIS...BJL NEAR TERM...BJL SHORT TERM...BAJ LONG TERM...DFH AVIATION...BAJ/BJL/DFH MARINE...BAJ/BJL/DFH CLIMATE...DFH/BJL

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.