Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 221817 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 217 PM EDT SAT AUG 22 2015 .SYNOPSIS... HIGH PRESSURE WILL DOMINATE THE AREA THROUGH THE WEEKEND. A COLD FRONT WILL APPROACH THE AREA FROM THE WEST ON MONDAY AND CROSS THE REGION MONDAY NIGHT. HIGH PRESSURE WILL THEN MOVE IN FROM THE WEST AND PERSIST THROUGH THE REMAINDER OF NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY NIGHT/... BROAD HIGH PRESSURE CENTERED OVER THE EASTERN GREAT LAKES WILL NARROW TONIGHT AS IT BECOMES SANDWICHED BETWEEN DEEPENING LOW PRESSURE OFFSHORE AND ANOTHER LOW PRESSURE SYSTEM APPROACHING FROM THE WEST. SHORTWAVE APPROACHING FROM THE SOUTHWEST WILL BRING INCREASED CLOUD COVER TO THE SW CORNER OF THE CWA...WHICH MAY AIDE IN MINIMIZING FOG DEVELOPMENT. ELSEWHERE...LIGHT/VRB FLOW AND CLEARER SKIES COULD LEAD TO PATCHY VALLEY FOG DEVELOPMENT. LOWS STILL SLIGHTLY BELOW NORMAL. ANY EARLY MORNING FOG WILL DISSIPATE WITH DAYBREAK. HIGH PRESSURE WILL RETREAT TO THE NORTH DURING THE DAY AS MULTIPLE LOWS APPROACH THE REGION. 12Z RUN OF HI- RES NMM AND ARM ALONG WITH THE NAM STILL HINTING AT AFTN CONVECTION DEVELOPMENT OVER THE WESTERN EDGE OF THE CWA WITH WEAK SFC CONVERGENCE AND MOISTURE ADVECTION FROM WINDS BCMG MORE SLY. PREVIOUSLY MENTIONED SHORTWAVE WILL ALSO PROVIDE FORCING ALOFT...SO WILL HAVE SLIGHT CHC POPS IN FOR THE AFTN/EARLY EVENING. ANY CONVECTION WILL TAPER OFF SUN EVENING. THE REMAINDER OF THE NIGHT EXPECTED TO BE DRY AHEAD OF THE APPROACHING COLD FRONT...WITH ANY PCPN REACHING THE WESTERN AREAS HOLDING OFF TILL AFTR 12Z MON. TEMPS RETURNING TO NEAR NORMAL FOR HIGHS SUN/LOWS SUN NIGHT. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... COLD FRONT WILL APPROACH FROM THE WEST ON MONDAY BEFORE CROSSING THE REGION MONDAY NIGHT. UNLIKE THE LAST FRONT...THIS SYSTEM WILL NOT BE ABLE TO TAP A LOT OF MOISTURE WITH PW`S STAYING BELOW 2 INCHES...AND EVEN BELOW 1.5 INCHES ON THE GFS. 0-6KM SHEAR ALSO STAYS FAIRLY WEAK WITH VALUES IN THE 20-25 KNOT RANGE. A LARGE DRY LAYER IS ALSO PROGGED TO BE PRESENT ALOFT. BOTTOM LINE...NOT EXPECTING A LOT OF STORMS TO FORM WITH THE FRONT...IN FACT IT WILL LIKELY BE A STRUGGLE TO GET ANY...THOUGH A FEW WILL PROBABLY GET GOING DURING THE AFTERNOON AND HEAD EAST DURING THE EVENING MONDAY BEFORE DISSIPATING OR MOVING OUT OF THE CWA. HIGHS MONDAY WILL BE IN THE UPPER 80S...FOLLOWED BY LOWS IN THE 50S AND 60S MONDAY NIGHT AND HIGHS DROPPING JUST A FEW DEGREES ON TUESDAY. HOWEVER...DEW POINTS WILL BE IN THE MID 60S IN MANY AREAS MONDAY BUT DROP DOWN TO THE LOW TO MID 50S ON TUESDAY AS HIGH PRESSURE BUILDS IN BEHIND THE FRONT...SO THE LACK OF HUMIDITY WILL BE THE MAIN FACTOR MAKING IT FEEL PLEASANT ON TUESDAY. OTHERWISE...EXPECT A FAIR AMOUNT OF SUN TUESDAY. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... HIGH PRESS DOMINATES DURING THIS PERIOD. THIS DRY AIR MASS WILL ALLOW FOR HIGH TEMPS TO BE IN THE 80S...AND LOWS IN THE 50S TO 60S. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... VFR CONDITIONS THROUGH THE TAF PERIOD. ANY PCPN SUN AFTN EXPECTED TO REMAIN WEST OF THE TAF SITES. WINDS INCREASING A BIT FROM THE SOUTH-SOUTHWEST ON MONDAY AHEAD OF NEXT COLD FRONT...THEN SHIFTING TO NORTHWEST OR NORTH BY TUESDAY...WITH SPEEDS IN THE 10-15 KNOT RANGE OVERALL. SUB-VFR CONDITIONS POSSIBLE LATER MONDAY AND MONDAY EVENING WITH A FEW SHOWERS AND THUNDERSTORMS...BUT COVERAGE DOES NOT LOOK HIGH. VFR CONDITIONS EXPECTED TUE THROUGH THE MIDDLE OF THE WEEK. && .MARINE... SUB-SCA CONDITIONS THROUGH SUN NIGHT. N FLOW AROUND 10 KTS BCMG SLY SUN AFTN 5-10 KTS. SOUTHERLY CHANNELING MAY GET GOING AHEAD OF THE APPROACHING COLD FRONT MONDAY...SO SMALL CRAFT CONDITIONS ARE POSSIBLE ON THE BAY. A FEW SHOWERS AND THUNDERSTORMS MAY ALSO OCCUR IN THE AFTERNOON AND EVENING. HIGH PRESSURE BUILDING IN TUESDAY WILL CLEAR OUT THE SHOWERS AND STORMS BUT THE PRESSURE GRADIENT MAY STILL BE TIGHT ENOUGH BEHIND THE FRONT TO BRING SOME MORE LOW-END SCA CONDITIONS. SUB-SCA CONDITIONS THEN EXPECTED TUE NIGHT INTO WED. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...RCM NEAR TERM...SEARS SHORT TERM...RCM LONG TERM...IMR AVIATION...SEARS/IMR/RCM MARINE...SEARS/IMR/RCM

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