000 FXUS61 KLWX 240907 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 407 AM EST TUE NOV 24 2009 .SYNOPSIS... LOW PRESSURE OFF THE NORTH CAROLINA COAST WILL TRACK EAST OF CAPE COD THIS AFTERNOON. HIGH PRESSURE WILL BUILD IN BEHIND THIS SYSTEM TODAY INTO WEDNESDAY. A STORM SYSTEM AND ITS ASSOCIATED COLD FRONT WILL PASS THROUGH THURSDAY...AND AN UPPER-LEVEL LOW BEHIND THIS FRONT WILL BRING UNSETTLED CONDITIONS LATE IN THE WEEK. HIGH PRESSURE WILL MOVE INTO THE AREA FOR THE WEEKEND. && .NEAR TERM /TODAY/... LOW PRES HAS BEEN SLOW TO DEPART THE NC CST...KEEPING MID ATLC LOCKED IN NE FLOW AND PDS OF RA/DZ. THE LOW RMNS PROGGED TO MOVE NE TDA...WHICH WL BRING AN END TO THE STEADIER RA BUT THERE IS NO MECHANISM TO SWEEP THE RMNG LO LVL MOISTURE OUT...SO CWA WL CONT TO XPRNC CONSIDERABLE LO CLDS ALONG W/ PDS OF DZ. VERY LTL MVMNT OF TEMPS - YDA HIGHS WERE IN U40S-L50S...AND THAT`S WHAT SHOULD HAPPEN AGN TDA. && .SHORT TERM /TONIGHT/... TNGT YOU COULD THINK OF IT AS THE MID ATLC WL BE UNDER WK HIGH PRES OR THAT IT WL BE IN BTWN SYSTEMS. EITHER WAY LO LVL MOISTURE WL RMN OVR THE CWA BRINGING XTNSV CLD CVR...AND PSBLY PLENTY OF FOG TNGT. MDLS ARE PREDICTING VSBYS BLO 1NM TNGT...I`M ALWAYS SKEPTICAL OF REALLY TANKING THE VSBY 24 HRS IN ADVANCE UNLESS WE`RE GOING TO XPRNC TOP NOTCH RAD CONDS..AND I DON`T THINK THIS WL NOT BE ONE OF THOSE NGTS. HOWEVER I`LL STILL MENTION FOG/DZ IN THE GRIDDS OVRNGT AND IF LATER SHIFTS THINK DIFFERENTLY THEY CAN TAKE VSBYS BLO 1SM FOR TNGT. AGN LTL MVMNT OF TEMPS - RANGE WL BE FM L40S IN THE HIGHLANDS TO A50 ON THE BAY. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... LEAD SHORTWAVE ENERGY EMBEDDED IN C CONUS H5 TROUGH WILL LIFT NWD THRU THE GREAT LAKES WED. ISENTROPIC LIFT AIDED BY SLY LLVL FLOW AND DPVA AHEAD OF SHORTWAVE TROUGH SHOULD PROVIDE ENOUGH FORCING FOR LGT SHOWERS DURING THE DAY WED. NEXT UPPER SHORTWAVE ENERGY WILL BE QUICK TO FOLLOW...DIGGING AROUND BACKSIDE OF SYNOPTIC-SCALE UPPER TROUGH WED/WED NGT. HEIGHT FALLS AHEAD OF THE UPPER TROUGH WILL LEAD TO COASTAL CYCLOGENESIS JUST OFF THE SE COAST LATE WED. SFC LOW WILL TRACK NEWD BUT SHOULD TRACK TOO FAR OFF THE COAST TO HAVE A DIRECT IMPACT TO OUR CWFA. HOWEVER... AMPLIFYING UPPER LOW AND STRENGTHENING THERMAL GRADIENT WILL PROVIDE FORCING FOR ASCENT AND PRECIP SHOULD INCREASE IN COVERAGE THU/THU NGT. 00Z SUITE OF MODELS SLIGHTLY SLOWER THAN PREV RUNS WITH THIS SYSTEM...AND THEREFORE MAJORITY OF THE SHOWER ACTIVITY MIGHT HOLD OFF UNTIL THE LATE AFTN/ERY EVNG ON THANKSGIVING. ATMOSPHERE WILL QUICKLY COOL BEHIND STRONG COLD FROPA THU NGT. THERMAL PROFILES APPEAR TO BE COLD ENOUGH TO SUPPORT PRECIP CHANGING TO SNOW ACROSS THE POTOMAC HIGHLANDS LATE THU NGT...AND POSSIBLY A RAIN/SNOW MIX AS FAR E AS THE BLUE RIDGE. CUTOFF LOW TRACKING OVER NEW ENGLAND WILL SLOW DOWN FRI AS UPPER TROUGH ACQUIRES NEGATIVE TILT. BREEZY CONDITIONS EXPECTED FRI AS STRONG CAA WILL STEEPEN LLVL LAPSE RATES AND ALLOW FOR STRONGER WINDS ALOFT TO MIX DOWN TO THE SFC. CORE OF COLD AIRMASS WILL BE OVRHD FRI NGT WITH A LGT RA/SN MIX AS FAR E AS I-95. UPSLOPE FLOW AROUND THE UPPER LOW MAY LEAD TO AN ACCUMULATING SNOW EVENT ACROSS THE WRN SLOPES OF THE ALLEGHENY FRONT AND POTOMAC HIGHLANDS THU NGT LASTING THRU SAT. TOO ERLY TO NAIL DOWN SPECIFIC SNOWFALL ACCUMULATIONS BUT THERE IS INCREASING CONFIDENCE FOR WINTER- WEATHER ADVISORY ACCUMULATIONS. HIPRES BUILDS BACK INTO THE AREA SUN...BEFORE THE NEXT STORM SYSTEM APPROACHES ERY NEXT WEEK. && .AVIATION /TODAY THROUGH SATURDAY/... ALL AIRPORTS IN THE MID ATLC STATES WL XPRNC XTNSV LOW LVL MOISTURE TDA AND TNGT. THIS WL BE MANIFESTED BY LO CIGS/POOR VSBY/PDS OF DZ. IFR/LO MVFR WL BE BE THE RULE BOTH TDA AT ALL SITES...PSBLY DROPPING TO LIFR OVRGNT. A STORM SYSTEM WILL APPROACH THE AREA WED WITH SCT SHOWERS AND MVFR CIGS. A STRONG UPPER LOW WILL QUICKLY FOLLOW THU-THU NGT...BRINGING MORE CHANCES FOR PRECIP. IN WAKE OF STRONG COLD FROPA THU NGT...SHSN MAY MIX IN WITH SHRA AT MRB THU NGT. GUSTY WINDS NW WINDS ARE EXPECTED ACROSS ALL TERMINALS FRI...LASTING INTO SAT. && .MARINE... WINDS HV DROPPED BLO SCA VALUES. LOW PRES WL BE TRACKING AWAY FM THE WATERS TDA LVG LTL PRES GRAD GRAD. NO PROBS ON WATERS TDA/TNGT OUTSIDE OF PTNL FOR POOR VSBYS IN FOG TNGT. WINDS SHOULD REMAIN BELOW SCA LVLS THRU THU. A STRONG COLD FROPA THU NGT WILL LEAD TO SCA CONDITIONS OVRNGT THU THRU SAT. DEPENDING ON HOW MUCH MIXING TAKES PLACE...GUSTS COULD APPROACH GALE WARNING CRITERIA FRI. && .TIDES/COASTAL FLOODING... WATER LVLS AT DC...ALEX...AND BALT IN THE MDNGT TIDAL CYCLE RAN CLOSE TO MINOR FLDG...BUT ALL STAYED BLO. CALLED THE ALEX EOC BUT THEY HAD NO FLDG "OF THE USUAL SUSPECTS." WINDS WL RMN FM THE NE TDA...AND ALTHO NOT STRONG THIS WON`T AID IN THE DRAINING PROCESS. HOWEVER THIS PAST TIDE CYCLE HAD THE HIGHEST LVLS OF TDA OR WED...SO AM GOING TO REFRAIN FM ISSUING A CSTL FLD ADVSRY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ PRODUCTS...WOODY!/JRK