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 190758 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 358 AM EDT TUE AUG 19 2014 .SYNOPSIS... LOW PRESSURE WILL MOVE AWAY FROM THE AREA TODAY...BUT A BOUNDARY WILL REMAIN STATIONARY OVER THE REGION. THE BOUNDARY WILL REMAIN OVERHEAD THROUGH THURSDAY BEFORE SLOWLY DROPPING SOUTH AS A COLD FRONT FRIDAY INTO THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... LOW PRESSURE IS LOCATED NEAR THE DELMARVA PENINSULA EARLY THIS MORNING AND A WEAK BOUNDARY EXTENDS FROM WESTERN MARYLAND THROUGH CENTRAL VIRGINIA. THERE IS A DEWPOINT GRADIENT ALONG THE BOUNDARY...BUT IT IS HARD TO SEE AT THIS TIME DUE TO THE NOCTURNAL INVERSION. PATCHY FOG IS EXPECTED MAINLY FOR LOCATIONS SOUTH AND WEST OF THE BOUNDARY ACROSS CENTRAL VIRGINIA INTO EASTERN WEST VIRGINIA. LOW PRESSURE WILL MOVE AWAY FROM THE REGION TODAY AND THE BOUNDARY WILL REMAIN NEARLY STATIONARY ACROSS WESTERN MARYLAND INTO CENTRAL VIRGINIA. SOME DRIER AIR WILL WORK ITS WAY IN FROM THE NORTH AND EAST ACROSS THE METROPOLITAN AREAS...LIKELY KEEPING THE DAY DRY WITH A SCT/BKN CU DECK DEVELOPING. HOWEVER...MOISTURE IS A BIT DEEPER SOUTH AND WEST OF THE BOUNDARY SO A FEW SHOWERS AND THUNDERSTORMS MAY POP UP ACROSS THE POTOMAC HIGHLANDS INTO CENTRAL VIRGINIA. EVEN ACROSS THESE AREAS...CONVECTION WILL BE SCATTERED DUE TO THE LACK OF A STRONG LIFTING MECHANISM. ANY CONVECTION WILL DISSIPATE ACROSS MOST LOCATIONS THIS EVENING. THERE MAY BE A FEW SHOWERS THAT HANG AROUND OVERNIGHT ACROSS THE POTOMAC HIGHLANDS...BUT EVEN ACROSS THESE AREAS MOST OF THE TIME WILL BE DRY. PATCHY LOW CLOUDS AND FOG ARE EXPECTED...ESPECIALLY ACROSS THE POTOMAC HIGHLANDS INTO CENTRAL VIRGINIA WHERE THERE WILL BE A LITTLE MORE MOISTURE. MIN TEMPS WILL RANGE FROM THE UPPER 50S AND LOWER 60S IN THE POTOMAC HIGHLANDS TO NEAR 70 IN DOWNTOWN WASHINGTON AND BALTIMORE. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... A STATIONARY BOUNDARY WILL REMAIN OVER THE REGION WEDNESDAY THROUGH WEDNESDAY NIGHT...BUT THERE WILL BE LITTLE TEMPERATURE OR DEWPOINT GRADIENT ALONG IT. AN UPPER-LEVEL LOW WILL DROP SOUTH THROUGH THE GREAT LAKES AND A SHORTWAVE OUT AHEAD OF IT WILL LIKELY PASS THROUGH THE AREA WEDNESDAY AFTERNOON INTO WEDNESDAY EVENING. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP WEDNESDAY AFTERNOON...ESPECIALLY NEAR AND WEST OF THE BLUE RIDGE MOUNTAINS. THE CONVECTION MAY TRACK FURTHER EAST INTO THE WASHINGTON AND BALTIMORE METROPOLITAN AREAS WEDNESDAY EVENING AS THE SHORTWAVE MOVES THROUGH. WEDNESDAY NIGHT WILL TURN OUT WARM AND HUMID ACROSS MOST LOCATIONS. CONVECTION SHOULD DISSIPATE ACROSS MOST AREAS OVERNIGHT DUE TO THE LOSS OF DAYTIME HEATING. AREAS OF LOW CLOUDS AND FOG ARE EXPECTED OVERNIGHT. && .LONG TERM /THURSDAY THROUGH MONDAY/... THE UPPER-LEVEL LOW OVER THE GREAT LAKES WILL SWING THROUGH OUR AREA LATER THURSDAY INTO THURSDAY NIGHT...BRINGING A CHANCE FOR MORE SHOWERS AND THUNDERSTORMS. H5 PATTERN IS ENERGETIC THROUGH THE PERIOD AS THE MID ATLANTIC IS CAUGHT BETWEEN A RETROGRADING UPPER LOW EAST OF THE CANADIAN MARITIMES AND LARGE ANTI-CYCLONE OVER THE LOWER MISSISSIPPI VALLEY. THE H5 CLOSED HIGH PRESSURE WINS OUT THROUGH THE PERIOD WITH HEIGHT RISES FOR OUR AREA...BUT WITH A SERIES OF VORT MAXES MOVING SOUTHEAST FROM THE GREAT LAKES. THE SFC REFLECTION IS AN INVERTED ANTICYCLONIC RIDGE EMANATING FROM THE SFC HIGH OVER THE CANADIAN MARITIMES. && .AVIATION /07Z TUESDAY THROUGH SATURDAY/... LOW CLOUDS AND PATCHY FOG WILL BRING MVFR/IFR CONDITIONS AT KCHO. LOW CLOUDS MAY ALSO MOVE INTO THE REST OF THE TERMINALS EARLY THIS MORNING...BUT CIGS SHOULD HOLD AT MVFR LEVELS. CONDITIONS WILL IMPROVE LATER THIS MORNING AND VFR CONDITIONS ARE EXPECTED ACROSS MOST AREAS THIS AFTERNOON. ANY SHOWER OR THUNDERSTORM WILL BE CONFINED TO KCHO THIS AFTERNOON AND EVENING. MORE LOW CLOUDS AND FOG IS POSSIBLE TONIGHT...AGAIN MAINLY ACROSS KCHO AND KMRB WHERE THERE WILL BE MORE MOISTURE. THERE IS A BETTER CHANCE FOR THUNDERSTORMS ACROSS THE TERMINALS LATER WEDNESDAY AND WEDNESDAY EVENING. LOW CLOUDS AND FOG MAY BE MORE WIDESPREAD OVERNIGHT WEDNESDAY INTO THURSDAY. MORE SHOWERS AND THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON AND EVENING. PERIODS OF MVFR/IFR CIGS ARE EXPECTED FROM LOW CLOUDS ASSOCIATED MARINE AIR. && .MARINE... A WAVE OF LOW PRESSURE WILL MOVE OFF TO THE EAST TODAY. AN EASTERLY FLOW WILL CONTINUE DURING THIS TIME...BUT WIND SPEEDS SHOULD REMAIN BELOW SCA CRITERIA. A STATIONARY BOUNDARY WILL REMAIN NEAR THE WATERS FOR WEDNESDAY AND THURSDAY. EAST TO SOUTHEAST WINDS ARE EXPECTED DURING THIS TIME...BUT WIND SPEEDS SHOULD REMAIN BELOW SCA CRITERIA. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE...MAINLY DURING THE AFTERNOON AND EVENING HOURS FOR WEDNESDAY AND THURSDAY. A BACKDOOR COLD FRONT WILL PASS THROUGH THE WATERS FRIDAY AND A NORTHEASTERLY FLOW IS EXPECTED DURING THE WEEKEND. NO MARINE HEADLINES ARE EXPECTED DURING THIS TIME. && .TIDES/COASTAL FLOODING... AN ONSHORE FLOW WILL CONTINUE THROUGH TONIGHT...BUT IT WILL REMAIN WEAK. TIDAL ANOMALIES AROUND ONE-HALF FOOT ABOVE NORMAL WILL LIKELY PERSIST THROUGH TONIGHT. MINOR TIDAL FLOODING IS NOT EXPECTED WITH THE LOWER OF THE TWO HIGH TIDES THIS AFTERNOON. WATER LEVELS WILL BE CLOSE TO MINOR FLOODING THRESHOLDS DURING THE HIGH TIDE CYCLE LATE TONIGHT...BUT CURRENT THINKING IS THAT WATER LEVELS WILL REMAIN BELOW MINOR FLOODING THRESHOLDS SINCE THE ONSHORE FLOW IS WEAK. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BJL NEAR TERM...BJL SHORT TERM...BJL LONG TERM...BJL/JEL AVIATION...BJL/JEL MARINE...BJL/JEL TIDES/COASTAL FLOODING...BJL

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