000 FXUS61 KLWX 130149 AAA AFDLWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 949 PM EDT MON MAY 12 2008 .SYNOPSIS... A DEEP LOW PRESSURE SYSTEM WILL MOVE INTO THE WESTERN ATLANTIC TONIGHT. HIGH PRESSURE WILL BUILD IN FOR TUESDAY AND WEDNESDAY. A WEAK COLD FRONT WILL CROSS THE WATERS THURSDAY. WEAK AREAS OF LOW PRESSURE WILL KEEP PRECIPITATION IN THE AREA THROUGH THE END OF THE WEEK...WITH A STRONGER UPPER LEVEL LOW PRESSURE AREA AFFECTING THE REGION DURING THE WEEKEND. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... SHOWERS STILL NOTED ON RADAR IMAGERY ROTATING SWD ON BACKSIDE OF UPPER LOW. LATEST SHORT-TERM GUIDANCE INDICATES THAT THESE WILL PERSIST UNTIL ABOUT 06Z WITH RAPID CLEARING INDICATED THEREAFTER. HELD TO A 20 PERCENT A LITTLE LONGER THAN PREVIOUSLY INDICATED. LOOKS LIKE ENOUGH PRES GRADIENT TO PREVENT WIDESPREAD FOG BUT CAN'T RULED OUT SOME LOCALIZED FOG WHERE WIND DECOUPLES ESPECIALLY IN VALLEYS. TOO LIGHT AND LOCALIZED TO MENTION IN ZFP/GRIDS. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... TUE THRU WED WL BE A TRANQUIL PD...AS ELONGATED RDG OF HIPRES PASSES OVR AREA. THE SFC RDG WL BE OHD TUE NGT...AND THE UPA REFLECTION PASSES WED. PGRAD RELAXES SIGNIFICANTLY ON TUE...SO WHILE THERE WL BE A NWLY BRZ...IT SHUDNT BE MUCH OVR 12 KT. LTL IF ANY WND TUE NGT...THEN THE RTN SLY FLOW COMMENCES WED. ALONG W/ THE RTN FLOW COMES A MARKED INCR IN CLDS FM ISENT LIFT. THAT LIFT WL YIELD ANTHR ROUND OF RA. ATTM...WL CONFINE START TIME TO WED NGT W OF I-95. THIS SYTM DOESNT HV THE SAME ORGANIZATION OF THE PRVS TWO...NOR WL IT HV ACCESS TO THE SAME TYPE OF MSTR SUPPLY. ASSOC CDFNT CROSSES THU. BUT DUE TO ITS STRENGTH...POPS WONT BE ANY HIER THAN CHC. EVEN PRIOR TO WAA...TEMPS JUMP UP SIGNIFICANTLY TMRW VS TDA. INSOLATION THE PRIMARY CONTRIBUTOR. THE 2NDRY CONTRIBUTOR WL BE WAA...COMING FM THE N! STAYED SLGTLY ON THE COOL SIDE ON THE MEAN FOR TEMPS. MAXT TUE NEAR 70. THEN SLY FLOW WED /H8 TEMPS UP FM 3-5C TUE TO 8-11C/ SHUD YIELD MID 70S. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... TO THE BEST OF CURRENT TIMING...THU NIGHT AND FRI THE NEXT WAVE OF SFC LOW PRES WILL MOVE UP FROM SW TO NE ACROSS THE REGION. THE UPPER TROF WILL FOLLOW FRI NIGHT AND SAT MORNING. THE NW FLOW AFTER THE UPPER TROF PASSAGE WILL MOVE A COLD FRONT THROUGH THE AREA SAT NIGHT. THAT WILL BE FOLLOWED BY A CLIPPER LOW ON EARLY MONDAY. THE END RESULT OF ALL IS THAT WE WILL BE IN AN ACTIVE WEATHER PATTERN THU NIGHT THRU EARLY NEXT WEEK. THE RAINIEST PERIOD WILL LIKELY BE THU NIGHT INTO FRI WITH THE SFC LOW. THE REST OF THE EXTENDED WILL BE MORE DRY THAN RAIN. HOWEVER WITH ALL OF THE MINOR SYSTEMS THAT ARE FORECAST TO COME THROUGH THERE WILL BE CHANCES OF RAIN THROUGH THE EXTENDED FORECAST. INDIVIDUAL TIMING OF EACH SYSTEM WILL LIKELY VARY BY A FRACTION OF A DAY. HIGH TEMPERATURES WILL BE A LITTLE BELOW NORMAL AND ARE FORECAST TO BE WITHIN A FEW DEGREES OF 70 FRI THRU MON IN THE LOWLANDS. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... MAINLY VFR XCPT FOR POSSIBLE BRIEF VIS RESTRICTIONS AT IAD/MRB. && .MARINE... LTST MAROBS SUGGEST A SOLID GLW AT TPLM2...AND SCA ELSW. LTST LWX-WRF-ARW4 SUGGESTS NLY CHANNELING DWN BAY SANDY PT S. IT MOST CLOSELY RESEMBLES ONGOING SITUATION...AND WL STICK CLOSE TO IT FOR TNGTS FCST. THAT SUGGESTS THAT GLW WL CONT FOR MAIN CHANNEL OF THE BAY THRU MIDNGT...AND WL SUBSIDE BELOW GLW THRAFTR. ELSW...MAIN THREAT OVR...AND HV LWD HEADLINES FM GLW TO SCA. DECENT MIXING WL CONT INTO TUE AFTN...SUFFICIENT TO WARRANT SCA. THRAFTR...NW FLOW SUBSIDES...AND BACKS SLY BY WED. NO OTR HEADLINES XPCTD ATTM. && .HYDROLOGY... UP TO 7 INCHES RECORDED IN NRN CALVERT COUNTY WITH WIDESPREAD 4-5 INCHES ACROSS THE WASH METRO AREA. A NEW PNS WITH RAINFALL TOTALS WAS ISSUED AROUND 830PM. MDT FLOODING EXPECTED ON THE MONOCACY RIVER AND MINOR FLOODING EXPECTED AT POINT ROCKS AND LITTLE FALLS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EDT TUESDAY FOR ANZ530-531- 535>537. SMALL CRAFT ADVISORY UNTIL 2 PM EDT TUESDAY FOR ANZ532>534. GALE WARNING UNTIL MIDNIGHT EDT TONIGHT FOR ANZ532>534. && $$ UPDATE...ROSA PRODUCTS...HTS/ROGOWSKI