000 FXUS61 KLWX 040147 AAA AFDLWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 947 PM EDT FRI JUL 3 2009 .SYNOPSIS... HIGH PRESSURE WILL BUILD OVER THE AREA BRIEFLY OVERNIGHT INTO SATURDAY. AN AREA OF LOW PRESSURE WILL PASS BY TO THE SOUTH SATURDAY NIGHT INTO SUNDAY BRINGING THE CHANCE FOR SHOWERS. THE COLD FRONT ASSOCIATED WITH THIS LOW WILL STALL OUT TO OUR SOUTH EARLY NEXT WEEK. HIGH PRESSURE WILL BUILD IN TOWARDS THE MIDDLE OF THE WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... A FEW REMNANT SHOWERS ALL THAT/S LEFT OF THE ACTIVITY FROM THE EXITING UPPER TROF AXIS...CURRENTLY SLIDING JUST OFF THE MID ATLC COAST. BEHIND THIS FEATURE IS BRIEF TRANSITION PERIOD W/ QUIET CONDITIONS LINGERING INTO EARLY/MIDDAY SAT. OVERNIGHT...THE SHOWERS WILL DISSIPATE COMPLETELY AND SO WILL THE ERN EDGES OF THE INCOMING MID LEVEL STRATUS. THE WRN HALF OF CWA WILL REMAIN MOSTLY CLOUDY AS THE BACKEDGE OF THE STEADY STRATUS SHIELD CONTINUES TO FILTER IN OVER THE CNTRL APLCNS FROM THE OHIO VLY. LOWS WILL AGAIN DROP INTO THE L60S EAST...U50S WEST. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/... SURFACE HIGH PRESSURE WILL BUILD OVER THE REGION SATURDAY...BUT THE NEXT DISTURBANCE WILL APPROACH THE REGION FROM THE MIDWEST DURING THE AFTERNOON. HIGH AND MID-LEVEL CLOUDS WILL INCREASE DURING THE AFTERNOON HOURS AHEAD OF THIS DISTURBANCE. MOST OF THE PRECIPITATION SHOULD HOLD OFF UNTIL SATURDAY NIGHT WHEN THE DISTURBANCE MOVES INTO THE REGION. HOWEVER...WILL CONTINUE WITH SLIGHT POPS LATER IN THE AFTERNOON DUE TO LIMITED INSTABILITY AND A WEAK PRESSURE TROUGH THAT DEVELOPS AT THE SURFACE DURING THE AFTERNOON. MAX TEMPS WILL BE CLOSE TO CLIMO...RANGING FROM THE 70S IN THE POTOMAC HIGHLANDS TO THE MID 80S IN WASHINGTON DC. A BAND OF MID LVL CNVGNC/FORCING ENTERS THE PICTURE FM W TO E SAT EVE. NAM12 GOING A LTL QUICKER/STRONGER WITH THIS FEATURE...BUT GIVEN ONGOING WK INSTBY THINK IT/S PRUDENT TO KEEP CHC POPS IN THE EVNG FCST. SINCE LIKELIHOOD OF TSRA WL IMPV THRU THE NGT...WL ALSO PROVIDE AN INCRG TREND...SPREADING SOME LKLY POPS BY MIDNGT. ATTM... HIEST POPS WL BE ACRS SRN HALF OF CWFA /DC-OKV SOUTH/...BUT ULTIMATELY IT WL DEPEND ON EXACTLY WHERE THAT BAND SETS UP. WL BE LOSING CONNECTION TO BNDRY LYR OVNGT...BUT FORCING IMPVS FURTHER. WL REPRESENT THAT IN WX GRIDS BY SHRA/SCHC TSRA. SUN APPEARS TO BE A WET DAY AS LOW TRACKS JUST S OF CWFA. ALTHO DONT THINK THAT SHRA WL BE CONTINUOUS...FVRBL LIFT WL PROVIDE POTENTIAL. AS WITH SAT NGT...THE SRN HALF OF CWFA WL BE CLOSEST TO THE FORCING...AND WL CARRY THE HIEST POPS. AS LOW TRACKS OFF DELMARVA COAST MID-LT AFTN...DRIER AIR WL INFILTRATE FM THE N/NW. IN ADDITION...INSTBY VIRTUALLY NIL AS COLUMN WL BE TOO SATD AND WNDS WL BE NLY. WL CARRY WX TYPE AS SHRA. THE LLVL MSTR/SHRA WL ALSO IMPEDE TEMP RISES. WL KEEP MAXT IN THE 70S...HIEST ACRS THE N WHERE PCPN WL BE SCARCEST. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... HIPRES RDG NOSES EWD IN WAKE OF LOW SUN NGT-MON. WL TRAIL POPS OFF DURING THE EVE...AND GO DRY SUN OVNGT-MON. AS CAA/NLY FLOW PICKS UP DURING DAY...CLDS WL SCT OUT AS MEAN LYR RH LOW...MAKING FOR A SUNNY/DRY DAY ON MON. BOTH MIN-T AND MAXT MON WL BE UNDER CLIMO...AS DEWPTS PROGGED IN THE 50S. XTNDD FCST ACRS CONUS WL FEATURE TROFS ALNG THE ATLC AND PAC CSTS AND BROAD RDGG ACRS THE CNTR OF THE CNTRY. THE RDGG WL BE BLDG EWD AS LOPRES IN CNDN MARITIMES EJECTS INTO THE NRN ATLC. H5 FLOW FAIRLY AMPLIFIED... AND AS SUCH...EVOLUTION WL BE ON THE SLOER SIDE. HOPEFULLY...THAT WL PERMIT A PD OF MORE STBL WX. WL GO W/ A BASICALLY DRY FCST TUE-FRI. TEMPS WON/T STRAY TOO FAR FM SEASONAL NORMS...ALTHO MIN-T W OF BLURDG WL BE RATHER COOL BASED ON DEWPTS WHICH STILL WL BE ON THE DRY SIDE. SUMMER HEAT AND HUMIDITY CUD BUILD BY WEEKS END...BUT WUD RATHER SEE SVRL CONSECUTIVE RUNS TRENDING THAT WAY. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS ARE EXPECTED THROUGH SATURDAY. WEST-NORTHWEST WINDS WILL DIMINISH LATE TONIGHT. A SIMILAR STORY ON SAT IN TERMS OF SFC WINDS...W/ A GRADUAL INCREASE OF WESTERLIES INTO THE MID AFTN HRS...THO LIKELY TOPPING OUT IN THE 10-15KT RANGE. ISOLATED CONVECTION CANNOT BE RULED OUT SATURDAY AFTERNOON...BUT THE BEST CHANCE FOR PRECIPITATION SHOULD HOLD OFF UNTIL SATURDAY NIGHT. SCT SHRA/TSRA WL APPROACH SAT NGT...AND SHRA WL CONT SUN. FLGT RESTRICTIONS LKLY...PRBLY MVFR ALTHO BRIEF PDS OF IFR PSBL. MAY ALSO SEE SOME OVNGT BR SUN NGT AS LLVLS WL BE MOIST FM DEPARTING RAIN. HWVR...DEWPTS LOW AND AMS MAY REMAIN MIXED. VFR CONDS XPCTD INTO MIDWEEK. && .MARINE... WINDS WILL CONTINUE TO DIMINISH TONIGHT AS THE PRESSURE GRADIENT WEAKENS. WESTERLY WINDS MAY GUST CLOSE TO SCA CRITERIA LATE SATURDAY MORNING INTO THE AFTERNOON...BUT WILL KEEP WIND GUSTS CAPPED AROUND 15 KNOTS FOR NOW DUE TO A WEAK PRESSURE GRADIENT AND A LACK OF STRONG WINDS ALOFT. SCT SHRA/TSRA WL APPROACH WATERS SAT NGT...AND SHRA WL CONT SUN. TSRA SAT NGT LKLY WL BE ELEVATED...THO LTNG WL STILL BE A RISK. WND DIR WL BE QUICK TRICKY SAT EVE...AS SLY FLOW ACRS VA AND NLY FLOW FM PTMC HIGHLANDS WL CONVERGE. THERE MAY BE SCA TYPE WNDS ONT HE MID BAY...BUT WAY TOO UNCERTAINOF THAT TO PLACE IN GRIDS ATTM. OVRALL... WNDS SHUD ATTAIN A NELY TRAJ BY ELY SUN...AND BACK NW BY SUN AFTN. PD OF PERSISTENT NWLY FLOW MON. APPEARS AS THO HIER WNDS MIX OUT PRIOR TO GOOD MOMENTUM TRANSFER. NO FLAGS ANTICIPATED TUE-WED EITHER. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ UPDATE...GMS PREV DISCUSSION...BJL/HTS