Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 262326 AAA AFDLWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 626 PM EST WED NOV 26 2014 .SYNOPSIS... COASTAL LOW PRESSURE 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. && .NEAR TERM /THROUGH THURSDAY/... COASTAL LOW PRESSURE CONTINUES TO PULL AWAY RAPIDLY TO THE NORTHEAST EARLY THIS EVENING. BEHIND THE LOW...SUBSIDENCE IS PUNCHING IN CAUSING A RAPID END TO THE PRECIPITATION ACROSS MUCH OF THE REGION. NE-MD WILL HOLD ONTO LIGHT SNOW...MIXED WITH RAIN IN A FEW LOCATIONS BUT ALL OF THIS WILL END WITHIN THE NEXT HALF HOUR TO HOUR. ACCUMULATING SNOWFALL HAS ENDED AND ALL WINTER WARNINGS AND ADVISORIES HAVE TERMINATED. TEMPERATURES WILL HOLD IN THE LOWER TO MIDDLE 30S FOR THE FIRST PART OF THIS EVENING BUT WILL FALL BELOW FREEZING OVER MUCH OF THE REGION LATER TONIGHT...AS SKIES CLEAR FROM WEST TO EAST. TWO CONCERNS FOR THE OVERNIGHT PERIOD...FIRST WILL BE RE-FREEZING OF WET ROADWAYS LEADING TO SLICK SPOTS. WILL CONSIDER AN SPS FOR THIS POTENTIAL. SECOND...CLEAR SKIES AND SNOWPACK WILL LIKELY LEAD TO PATCHY DENSE FOG OVERNIGHT ESPECIALLY WEST OF THE BLUE RIDGE. HAVE UPDATED THE HAZARDOUS WEATHER OUTLOOK TO ACCOUNT FOR THIS. WILL MONITOR FOG COVERAGE TO SEE IF A DENSE FOG ADVISORY IS WARRANTED. 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. 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. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... 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. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... 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. && .AVIATION /23Z WEDNESDAY THROUGH MONDAY/... CONDITIONS WILL CONTINUE TO IMPROVE AT ALL TERMINAL SITES THE REMAINDER OF THIS EVENING. POTENTIAL EXISTS FOR PATCHY DENSE FOG OVERNIGHT. 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. && .MARINE... SMALL CRAFT CONDITIONS WILL CONTINUE OVER MUCH OF THE WATERS OVER THE NEXT SEVERAL HOURS. WINDS WILL GRADUALLY DIMINISH OVERNIGHT. 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. && .CLIMATE... 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 1.6 INCHES /AS OF 3 PM/ 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) && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR ANZ530>534- 536>543. SMALL CRAFT ADVISORY FROM 7 PM THURSDAY TO 6 PM EST FRIDAY FOR ANZ530>534-536-537-539>541-543. SMALL CRAFT ADVISORY FROM 8 AM TO 6 PM EST FRIDAY FOR ANZ535- 538-542. && $$ SYNOPSIS...KRW NEAR TERM...KRW SHORT TERM...BAJ LONG TERM...DFH AVIATION...KRW/DFH MARINE...KRW/DFH CLIMATE...KRW/DFH

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