000 FXUS61 KLWX 270019 AAA AFDLWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 819 PM EDT SUN APR 26 2009 .SYNOPSIS... SUBTROPICAL HIGH PRESSURE OVER THE WESTERN ATLANTIC WILL CONTINUE TO BRING VERY WARM CONDITIONS THROUGH EARLY NEXT WEEK. THE NEXT FRONTAL SYSTEM WILL AFFECT THE AREA TUESDAY NIGHT AND WEDNESDAY...BRINGING A GOOD CHANCE FOR PRECIPITATION ALONG WITH COOLER CONDITIONS. THE FRONT WILL REMAIN IN THE MID ATLANTIC AND CAROLINAS THROUGH THE END OF THE WEEK. && .NEAR TERM /THROUGH MONDAY/... VERY TINY...ISOLD CELL MOVG ACRS NERN PORTION OF FCST AREA ATTM. SCT CNVCTV CLDS DISSIPATING ACRS SWRN ZONES. WILL TRIM POPS BACK WITH UPDATE AND LMT PCPN CHCS TO CURRENT CNVCTN. WITH SUBTROPICAL RDG XPCD TO ASSERT ITSELF MORE PROMINENTLY BGNG LATE TNGT...LITTLE IMPETUS FOR RENEWED CNVCTN TO DVLP AS BNDRY LYR STABILIZES AND SUBSIDENCE INCRS AMIDST NWD-DVLPG UPR RDG. MINOR ADJUSTMENTS TO GRIDS ALSO MADE TO REFLECT CURRENT OBS AND XPCD TRENDS. PREV DISCUSSION FOLLOWS... CURRENT ANALYSIS SHOWS A SURFACE HIGH OVER THE WESTERN ATLANTIC AND A MID-LEVEL HIGH ALONG THE MID-ATLANTIC AND SOUTHEAST COAST. A PRESSURE TROUGH REMAINS OVER THE SHENANDOAH VALLEY AND A BAY BREEZE HAS BEGUN TO PUSH INLAND FROM THE CHESAPEAKE BAY. LATEST SATELLITE IMAGERY SHOWS CU DEVELOPMENT OVER THE HIGHER TERRAIN OF THE POTOMAC HIGHLANDS AND BLUE RIDGE MOUNTAINS. WITH THE STRONG SURFACE HEATING...THERE WILL BE SOME INSTABILITY LATER THIS AFTERNOON INTO THIS EVENING. THE MID-LEVEL HIGH HAS PRODUCED A CAPPING INVERSION...BUT IT REMAINS RATHER WEAK. WITH THE TERRAIN CIRCULATION AND THE PRESSURE TROUGH/BAY BREEZE ACTING AS TRIGGERS...THIS SHOULD BE ENOUGH TO BREAK THE CAP PRODUCING ISOLATED TO SCATTERED CONVECTION. DEWPOINTS HAVE MIXED DOWN INTO THE UPPER 40S AND LOWER 50S ACROSS MOST LOCATIONS THIS AFTERNOON. THE LOWER DEWPOINTS AND THE CAPPING INVERSION SHOULD INHIBIT THE AMOUNT OF INSTABILITY THAT WILL DEVELOP TO GENERALLY UNDER 1000 J/KG OF MLCAPE. THEREFORE...MOST THUNDERSTORMS THIS AFTERNOON AND EVENING SHOULD BE SUBSEVERE. ANY CONVECTION THIS EVENING SHOULD DISSIPATE OVERNIGHT WITH THE LOSS OF DAYTIME HEATING. HIGH PRESSURE OVER THE WESTERN ATLANTIC WILL CONTINUE TO PUMP A SOUTH-SOUTHWEST FLOW INTO THE REGION ALLOWING FOR ANOTHER MILD NIGHT. MIN TEMPS WILL RANGE FROM THE LOWER 50S IN THE COOLER VALLEYS OVER THE SHENANDOAH VALLEY AND POTOMAC HIGHLANDS TO THE UPPER 60S IN DOWNTOWN WASHINGTON AND BALTIMORE. && .SHORT TERM /MONDAY NIGHT/... THE MID-LEVEL HIGH WILL BUILD NORTHWEST TOWARDS OUR CWA MONDAY PROVIDING MORE SUBSIDENCE. WITH THE SURFACE HIGH OVER THE WESTERN ATLANTIC...THIS WILL PRODUCE A SOUTHWEST FLOW OVER THE REGION. THE COMBINATION OF THE MID-LEVEL HIGH AND THE SOUTHWEST FLOW WILL ONCE AGAIN BRING ANOTHER HOT AFTERNOON TO THE REGION. THERE WILL BE PLENTY OF SUNSHINE AND NO CHANCE FOR THUNDERSTORMS DUE TO THE SUBSIDENCE. CWFA WL STILL BE UNDER SUBTRPCL RDG MON NGT. XPCT A DELAYED RESPONSE IN DSPTG DAY/S HTG...AS A LGT SLY FLOW REMAINS. HV THUS FCST ON WARM END OF MOS FOR MIN-T...UNDER CLR SKIES. && .LONG TERM /TUESDAY THROUGH SUNDAY/... RDG WL BEGIN TO BRK DWN TUE...AS STRONG CDFNT PLOWS EWD. HWVR...LCL TIMING OF FROPA...MAINLY TUE NGT AND ELY WED MRNG...NOT FVRBL IN TERMS OF REALIZING STRONG TSRA. JUST ENUF INSTBY SNEAKS INTO MTNS TUE AFTN TO COMBINE W/ TRRN CIRCULATION...PRODUCING A RANDOM TSRA. THE SWATH OF POTL PCPN THEN ADVCS ACRS CWFA TUE NGT. XPCT BETTER CVRG AS FNT WL PROVIDE AMPLE CNVGNC/LIFT. BUT...STORMS SHUD BECOME ELEVATED BY MRNG AS BNDRY LYR COOLS. QUITE A SPREAD IN TERMS OF TEMPS TUE. BASED ON HGTS...NOT SEE THAT MUCH COOLING TUE VS MON...AND HV LEANED CLSR TO WARMER MAV FOR MAXT. FOR MIN-T...WENT BTWN MEAN AND THE HIER END. CAA NOT ALL THAT STRONG...AND THE MOIST ENVIRONMENT NOT CONDUCIVE FOR BIG TEMP DROPS. TYPICALLY HOT SPELLS IN SPRING BREAK WITH STRONG/SVR TSRA. HWVR... CWFA MAY STAY JUST COOL/MOIST ENUF THRUT TO PRECLUDE BIG TSRA WED. IF IT WERE TO OCCUR...AFTN WUD BE PREFERRED AS CONTRIBUTION FM DIURNAL HTG REALIZED...AND SOME OF THE MSTR W/IN COLUMN HAS A CHC TO MIX OUT. BUT BY THEN...FLOW NLY BHD FNT. WL STAY W/ A STRAY RUMBLE IN THE MRNG...AND CARRY CHC IN THE AFTN. MAXT WL BE MUCH COOLER... CLSR TO NRML. FNTL BNDRY WL BE LURKING ACRS THE MID ATLC/CAROLINAS THRU THE XTNDD PD. AFTER PARKING S OF AREA WED NGT...LOPRES MVG THRU MIDWEST/GRTLKS THU LKLY WL PULL IT BACK N AS WMFNT THU NGT-FRI. ATTENDANT CDFNT WUD THEN COME THRU FRI NGT-SAT. WL HV HIER POPS /40 PCT/ INVOF BOTH FRNTS. WL ADD TSRA IN THE AFTN-EVE ON WARM SIDE OF BNDRY...AND AGN SAT WHEN LAPSE RATES SHUD BE STEEPER. HWVR...PCPN SAT WL BE MUCH MORE CONDTL BHD CDFNT. TEMPS WL BE MUCH CLSR TO NRML...UNLIKE THE CRRNT PTTN. HIPRES PUSHING IN SAT NGT-SUN SHUD PROVIDE A MORE STBL...LESS HUMID...AND PCPN FREE PD. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... UPR RDG ASSERTS ITSELF TNGT THRU MON...WITH SKIES CLRG THIS EVE ONCE TENACIOUS CNVCTN DISSIPATES. LGT WINDS OVRNGT WILL GIVE WAY TO GUSTY SWLY WINDS BY MON AFTN. VFR TUE...THEN OCNL SHRA/TSRA MVG IN TUE NGT INVOF CDFNT...AND LURKING ARND THRU REST OF WK AS FNT WAVERS ACRS MID ATLC/CAROLINAS. VFR CONDS LKLY TO PREVAIL...BUT WL BE PDS OF MVFR-IFR. PDS AT HIGHTENED CHCS TUE NGT-WED MRNG...THU NGT-FRI MRNG...AND AGN FRI NGT-SAT MRNG. && .MARINE... WINDS SHUD RMN BLW SMALL CRAFT ADZY CRITERION TNGT. SWLY WINDS XPCD TO INCR LATE MON MRNG...WITH GUSTS AOA 20KT XPCD ACRS POTOMAC. WILL CONT SMALL CRAFT ADZY ISSUED ON PREV SHIFT WITH NO EXPANSION AS COOLER WATERS IN CHSPK BAY XPCD TO LMT GUSTINESS OWING TO GREATER STABILITY. MAY SEE SOME SLY CHANNELING MON NGT. WNDS PICK UP TUE AS P-GRAD TIGHTENS BTWN SUBTROPICAL HIGH AND PENDING CDFNT. SCA LKLY BY TUE AFTN...CONTG THRU TUE EVE. TSRA PSBL TUE NGT IN ADVC OF CDFNT... SOME OF WHICH MAY REQUIRE SMW/S. FROPA WED MRNG SHIFTS WNDS TO NLY. PCPN CHCS CONT THRU END OF WK. && .FIRE WEATHER... FUEL MOISTURE REMAINS QUITE LOW THIS AFTERNOON AND THE RELATIVE HUMIDITY HAS DROPPED TO NEAR OR BELOW 30 PERCENT ACROSS MOST LOCATIONS. HOWEVER...WINDS REMAIN LIGHT. THE DRY CONDITIONS WILL STILL POSE AN INCREASED FIRE THREAT LATE THIS AFTERNOON. THE RELATIVE HUMIDITY WILL INCREASE THIS EVENING AND LIGHT WINDS ARE EXPECTED TONIGHT. HOWEVER...WIND SPEEDS ARE EXPECTED TO INCREASE LATER MONDAY MORNING AND AFTERNOON...AVERAGING AROUND 15 MPH WITH GUSTS OVER 20 MPH. FUEL MOISTURES WILL REMAIN QUITE LOW AND THE RELATIVE HUMIDITY WILL DROP BELOW 30 PERCENT ACROSS MOST LOCATIONS. AN ENHANCED FIRE THREAT IS EXPECTED LATER MONDAY MORNING AND AFTERNOON. && .CLIMATE... RECORD HIGH TEMPERATURES FOR 04/26 THRU 04/28 FOR SELECTED CLIMATE SITES... ..04/26....04/27....04/28 BWI..92.1990..92.1994..90.1957 DCA..94.1915..95.1915..92.1957 IAD..92.1990..92.1990..88.1990 MRB..92.1990..91.1957..92.1935 && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON TO 7 PM EDT MONDAY FOR ANZ535>537. && $$ UPDATE...KRAMAR PREV DISCUSSION...LASORSA/HTS