Issued by NWS Sterling, VA
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-- Discussion containing changed information from previous version are highlighted. --000 FXUS61 KLWX 210213 AAA AFDLWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 913 PM EST FRI NOV 20 2009 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH SATURDAY. HIGH PRESSURE WILL RETREAT TO THE NORTH SUNDAY AND LOW PRESSURE WILL MOVE UP THE EASTERN SEABOARD SUNDAY NIGHT THROUGH MONDAY NIGHT...BRINGING ANOTHER ROUND OF RAIN. HIGH PRESSURE WILL RETURN TUESDAY...BUT A COLD FRONT WILL PASS THROUGH DURING THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 7 AM SATURDAY MORNING/...-- Changed Discussion --A RESIDUAL UPPER WAVE REMAINS BACK TO THE NW...SLIDING DOWN THRU THE UPPER MIDWEST TONIGHT W/ LITTLE-NO PRECIP BUT A LARGE MASS OF LOW CLOUDS STREAMING FROM THE SHORES OF LAKE ERIE DOWN INTO THE CNTRL APLCNS. THIS WILL BE ABOUT THE ONLY WX ACTIVITY FOR THE REGION INTO THE EARLY PART OF THE WEEKEND. PORTIONS OF THIS CLOUD BANK WILL BREAK-UP AND SLIDE DOWN ACROSS THE NRN SHENANDOAH VLY AND POTOMAC HIGHLANDS THRU THE OVERNIGHT HRS. WINDS DECREASING AND AFTER A LONG PERIOD OF NWLY WINDS THIS AFTN...CONDITIONS ARE RELATIVELY DRY...SO WIDESPREAD FOG DEVELOPMENT NOT EXPECTED /OUTSIDE OF SHELTERED VLYS AND OTHER TYPICAL FOG-PRONE AREAS TOWARD THE PRE-DAWN HRS/. THE RELATIVELY DRY CONDITIONS WILL ALSO ALLOW TEMPS TO SLIDE DOWN INTO M/U30S /L40S IN THE METRO AREAS AND CLOSER TO THE BAY/.-- End Changed Discussion --&& .SHORT TERM /7 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... SURFACE HIGH WILL REMAIN OVER THE REGION SATURDAY BRINGING DRY AND SEASONABLE CONDITIONS. MAX TEMPS WILL BE IN THE MID TO UPPER 50S ACROSS MOST LOCATIONS. MOSTLY/PARTLY SUNNY SKIES ARE EXPECTED WITH A SCATTERED CU DECK DUE TO DIURNAL HEATING AND SOME HIGH CLOUDS DUE TO A SOUTHWEST FLOW ALOFT. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... LRG HIPRES HANGING OUT ACRS THE NE/GRTLKS RGN SAT NGT-SUN. DIFF THIS CYCLE IS THE COMBO OF SFC HIGH AND H5 RDGG...MAKING IT HARDER TO DISLODGE. THRFR..GDNC THIS CYCLE SLOER THAN PRVS CYCLES. GFS SEEMS TO BE QUICKER...BUT IT ALSO SEEMS TO BE AFFECTED BY GRIDSCALE FEEDBACK...OWING TO S/WV PHASING. GGEM/NAM IN CONCERT...SUGGESTING PCPN WL BE CENTERED ON SUN NGT-MON. A WK LOW WL THEN EMERGE OFF MID ATLC CST MON NGT. WL MAKE APPRO CHGS TO GRIDS. ONE THING OF NOTE IS THAT THERE/S NO COLD AIR ARND. AFTR MAKING APPRO MOS TEMP ADJUSTMENTS /NEGLECTING THE COOLER MAXT OF WET GFS AND SIDING WARMER SUN NGT AS CLDS ADVECT NWD/...MAXT WL BE NEAR NRML BUT MIN-T WARMER THAN NRML. SHUD GET A RESPITE TUE BEFORE ANTHR STORM AFFECTS CWFA IN THE WED-THU TIMEFRAME. WL NEED TO MONITOR DUE TO TRAVEL IMPACTS. ATTM... THE WARM TREND CONTS AS A CUTOFF H5 LOW DVLPS W OF THE MISSISSIPPI. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...-- Changed Discussion --HIGH PRESSURE WILL BRING VFR CONDITIONS THROUGH SATURDAY. A SCATTERED STRATUS DECK /3-4 KFT/ WILL CONTINUE TO DRIFT IN FROM THE NW /BUT ONLY IN SMALLER PORTIONS FROM ITS LARGER MASS - BACK ACROSS OH/WRN PA. THIS AREA OF CLOUDS WILL CONTINUE TO MOVE INTO THE AREA TOWARD SATURDAY MORNING AND INTO THE AFTERNOON...DRIFTING THRU AND DISSIPATING BY LATER IN THE EVNG. WIND SPEEDS WILL REMAIN BELOW 10 KNOTS THRU THIS TIME. VFR THRU SUN. FLGT RESTRICTION DUE TO LOPRES SUN NGT-MON NGT.-- End Changed Discussion --&& .MARINE...-- Changed Discussion --NLY WINDS WILL CONTINUE TO MOVE OVER THE WATERS OVERNIGHT...AND HIGH PRESSURE BEGINS TO MOVE IN FROM THE WEST...THOUGH WINDS WILL BE LIGHT W/ A MINIMAL PRES GRADIENT...SO NO WX CONCERNS INTO THE WEEKEND. NO FLAGS XPCTD THRU THE WKND. LOPRES AFFECTING WATERS MON. WNDS MAY PICK UP IN ADVC OF LOW...W/ A ENELY FETCH.-- End Changed Discussion --&& .LWX WATCHES/WARNINGS/ADVISORIES...-- Changed Discussion --DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE.-- End Changed Discussion --&& $$ UPDATE...GMS PREV DISCUSSION...BJL/HTS
