AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1022 AM EDT FRI JUL 8 2011 .SYNOPSIS... A COLD FRONT WILL PUSH FROM THE LOWER GREAT LAKES INTO THE MID ALTANTIC THIS AFTERNOON AND EVENING...AND OFF THE DELMARVA COAST EARLY SATURDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTH SATURDAY AND REMAIN IN PLACE THROUGH THE WEEKEND. A SECOND FRONT WILL PUSH SOUTH ACROSS THE MID ATLANTIC LATE MONDAY INTO TUESDAY...WITH HIGH PRESSURE RETURNING FOR THE SECOND HALF OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... CDFNT STRETCHES FM NEAR PAH-CLE ATTM. RGNL RDR COMPOSITE DEPICTS A SWATH OF SHRA/TSRA AHD OF THE FNT...IN THE AREA OF GOOD SWLY MSTR CNVGNC/ADVECTION. THERE WAS A 2ND AREA OF TSRA NOTED...PARKED JUST SE OF CWFA...MOST LKLY TRIGGERED BY SPD CNVGNC. THAT AREA SLIDING TO THE E...AND SHUD BE OUT OF THE PICTURE BY 15Z. CDFNT/TROF AXIS APPEARS TO BE ADVCG A BIT QUICKER THAN PROGGED ERLR. BUT...ORIENTATION OF SFC FNT SHUD BECOME QUITE PARALLEL TO H8-5 HGTS...SO DO XPCT FNT TO STALL /OR AT LEAST SLOW DOWN/ ACRS SRN CWFA TAFTN-EVE. 12Z IAD SNDG UNSTBL RIGHT OFF THE BAT...W/ OVER 2000 J/KG SBCAPE. MODIFIED IT BAS PRTLY OFF THE PBZ SNDG...AS THE RELATIVELY DRY MID LVLS SHUD BE MSTNG. DCA TEMP 80F ATTM...SO LAMP PROG OF 85F VERY REASONABLE EVEN W/ LTL OPPORTUNITY FOR INSOLATION. THAT PLACES COLUMN AT THE TRIGGER TEMP. SHEAR A BIT BETTER THAN YDA...AND SHUD BE IMPVG. SO...TSRA SHUD DVLP AHD OF MAIN BATCH. THESE WUD BE CAPABLE OF STRONG GUSTY WINDS. EVENTUALLY THOSE STORMS WL BE OVERCOME BY THE ACTIVITY AHD OF THE S/WV /WHICH HAS FVRBL UPR JET SUPPORT AS WELL/. THUS...THREAT AT THAT PT SHUD TRANSITION FM GUSTY WND TO HVY RAIN. OBVSD PWAT FM SNDG 1/57. MODIFIED YIELDS 1.75. NAM/GFS BOTH PAINT A PATH OF PWAT AOA 2 INCHES...MAINLY ALONG/E OF I-95. NOT QUITE AS HIGH AS GDNC YDA...BUT STILL RESPECTABLE AND MORE THAN ENUF FOR TRAINING ECHOES TO YIELD FLASH FLOODING. FNT WL SLOWLY BE SHOVED SEWD OVNGT. SHUD HV LINGERING ACTIVITY... SPCLY ACRS SRN MD. HWVR...MOST OF THE PCPN WL TAKE PLACE BEFORE MIDNGT. && .SHORT TERM /SATURDAY THROUGH MONDAY/... LINGERING SHOWERS ASSOCIATED WITH A SLOW MOVING FRONTAL BOUNDARY POSSIBLE ACROSS THE SOUTHERN PORTION OF THE CWFA EARLY SATURDAY MORNING. PRECIP SHOULD TAPER OFF BY THE AFTERNOON AS THE FRONT CONTINUES SOUTHWARD AND HIGH PRESSURE BUILDS IN FROM THE NORTH. HIGH PRESSURE WILL REMAIN THE DOMINANT WEATHER FEATURE THROUGH THE WEEKEND...BUT WILL MOVE OFFSHORE ON MONDAY. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... A SECOND FRONT IS EXPECTED TO IMPACT THE CWFA BY LATE MONDAY/EARLY TUESDAY BRINGING ANOTHER CHANCE OF SHOWERS/TSRA. HIGH PRESSURE BUILDS IN FROM THE NORTH FOR THE LATTER HALF OF THE WEEK. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... A VEIL OF HIGH CLDS ACRS TERMINALS. HV SEEN LCL/BRIEF FORAYS BLO 1K FT /SUCH AS MRB ATTM/...BUT THEY HVNT LASTED LONG ENUF TO MNTN IN TAFS. A LARGE AREA OF SHRA/TSTMS IN UPR OHVLY WL SPREAD EWD TAFTN-TNGT. XPCT ADDTL TSRA TO DVLP AHD OF THIS ACTIVITY BY ELY-MID AFTN. TSTMS CARRY A GUSTY WIND AND HVY RAIN THREAT. VSBY RESTRICTIONS AOB IFR PSBL...BUT TIMING THAT PROBLEMATIC AT THIS POINT. ATTM AM ONLY CARRYING MVFR DURING WINDOW OF GREATEST OPPORTUNITY. PLAN ON REFINING THAT...PRBLY BY NXT CYCLE. CONDITIONS WILL IMPROVE GRADUALLY DURING THE PREDAWN HRS SAT...AS A FRONT SLIDES DOWN FROM THE NW AND SWEEPS THIS ACTIVITY OFF THE COAST. SUB VFR CONDITIONS POSSIBLE AT KCHO EARLY SATURDAY MORNING. HOWEVER...ANY LINGERING SHOWERS FROM THE SLOW MOVING FRONT SHOULD BEGIN TO PUSH SOUTHWARD BY THE AFTERNOON. NO CIG/VSBY RESTRICTIONS EXPECTED FOR THE REMAINDER OF THE WEEKEND. A SECOND FRONT COULD BRING SUB VFR CONDITIONS BACK TO THE REGION LATE MONDAY INTO TUESDAY. && .MARINE... S/SWLY FLOW 10-15 KT ATTM. DONT ENVISION MUCH OF A CHG TO THAT THRU THE AFTN. SHOWERS AND SOME TSTM ACTIVITY WILL DEVELOP AS THE DAY PROGRESSES AND AFFECT THE WATERS WELL INTO THE OVERNIGHT HRS. SMW/S WL BE PSBL UNDER/AHD OF THE STRONGEST STORMS. THE STATIONARY BOUNDARY WILL GRADUALLY DRIFT SEWD AS A CDFNT LT TNGT...AND OFF THE COAST INTO THE PREDAWN HRS SAT. HIGH PRESSURE BUILDS IN BEHIND A FRONT ON SATURDAY. HIGH PRESSURE REMAINS OVERHEAD THROUGH EARLY MONDAY. AS SECOND FRONT MAY IMPACT THE WATERS BY LATE MONDAY/EARLY TUESDAY. NO HEADLINES ANTICIPATED AT THIS TIME. && .HYDROLOGY... NO CHANGES TO THE FLASH FLOOD WATCH AT THIS TIME...AND POTENTIAL FOR HEAVY RAINS CONTINUES AS TROPICAL MOISTURE FROM THE GULF OF MEXICO INTERACTS WITH A SLOW MOVING FRONTAL BOUNDARY. MODELS PROG THE PWATS THIS EVENING AROUND 2 INCHES...WHICH IS ARND 2SD ABOVE NORMAL. IN ADDITION...QUASI-STATIONARY/SLOW MOVING FRONT WILL PROVIDE A FOCUS FOR TRAINING STORMS. BOUNDARY LAYER FLOW ALSO REMAINS LIGHT AOB 15KT. ATMOS REMAINS UNSTABLE WITH DEWPOINTS IN THE LOWER 70S. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR DCZ001. MD...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR MDZ004>007-009>011- 013-014-016>018. VA...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR VAZ025>027-029>031- 036>040-042-050>057-501>504. WV...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR WVZ505-506. MARINE...NONE. && $$ SYNOPSIS...HTS