AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 631 AM EDT TUE APR 19 2011 .SYNOPSIS... HIGH PRESSURE REMAINS ANCHORED OFF THE SOUTHEAST COAST THROUGH WEDNESDAY. LOW PRESSURE TRACKS NORTHEAST FROM THE MID MISSISSIPPI VALLEY TONIGHT...AND INTO THE ST LAWRENCE VALLEY ON WEDNESDAY. THIS WILL PUSH A COLD FRONT THROUGH THE MID ATLANTIC STATES WEDNESDAY NIGHT. HIGH PRESSURE RETURNS ON THURSDAY...AND BECOMES CENTERED OFF THE NEW ENGLAND COAST ON FRIDAY. A WARM FRONT WILL LIFT NORTH THROUGH THE REGION LATE FRIDAY INTO SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... STATUS ON POST-STORM SURVEYS... PRELIMINARY REPORTS FROM SATURDAYS TORNADOES HAVE BEEN COMPLETED FOR BERTIE AND GATES (NEW) COUNTY NC...CURRITUCK (NEW) COUNTY NC...AND ALSO FOR DINWIDDIE COUNTY AND ISLE OF WIGHT COUNTY IN VA. A COMPLETE REPORT FOR GLOUCESTER / MIDDLESEX & MATHEWS COUNTY, VA TUESDAY MORNING...AND LUNENBURG / MECKLENBURG COUNTY, VA LATER ON TUESDAY. PLEASE SEE THE LATEST PUBLIC INFORMATION STATEMENT (WBCPNSAKQ)... LOCAL STORM REPORTS (WBCLSRAKQ)... AS WELL AS AVAILABLE ON THE TOP OUR WEBSITE (WWW.WEATHER.GOV/WAKEFIELD) UNDER "NEWS OF THE DAY" FOR MORE INFORMATION. STORM SURVEYS MAY NOT BE FINALIZED TILL LATER ON THIS WEEK...BUT TO BE COMPLETED AS SOON AS POSSIBLE. NEAR TERM FORECAST DISCUSSION... EARLY MORNING WX ANALYSIS SHOWING SFC HIGH PRESSURE STILL ANCHORED WELL OFF THE SE COAST...WITH QUASI-STATIONARY/WARM FRNTL BNDRY ALIGNED NEARLY WEST TO EAST FROM SRN OHIO EASTWARD TO NEAR THE MASON DIXON LINE. AREA OF CONVECTION IS ONGOING ALONG THE BNDRY IN SRN IND AND OHIO. MAIN FCST CHALLENGE TODAY CONCERNS THE EVOLUTION OF THE BNDRY. MID/UPR LVL FLOW TURNING SLIGHTLY MORE TO THE WSW WOULD SUGGEST THE FRONT ACTUALLY LIFTS A BIT TO THE NORTH LATER TODAY. HAVE THEREFORE KEPT FCST DRY FOR ALL AREAS LATER TODAY AND TONIGHT...ALTHOUGH THERE WILL BE A FAIR AMT OF MID/HIGH LVL CLOUDINESS AROUND ESPECIALLY ACRS NRN TIER OF CWA. ELSEWHERE SKIES AVG PT SUNNY WITH LOW LVL THICKNESSES AND H85 TMPS YIELDING HIGHS A FEW DEGREES WARMER THAN YSDY...80-85 W OF BAY...70S ERN SHORE. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... AS THE FRONT APPROACHES TONIGHT...DECENT LOW LVL SOUTHERLY FLOW/MIXING...LOOKS TO MAKE FOR A VERY WARM NIGHT...WENT ON HIGH SIDE OF GDNC WITH LOWS MAINLY IN THE LWR 60S...UPR 50S ERN SHORE. SNDGS STILL SHOW SOME SHALLOW LOW LVL MSTR...CLIMO SUGGESTS LMTD POTENTIAL FOR FOG DESPITE INCRSG DEW PTS...COULD SEE SOME PATCHY LOW LVL STRATUS SO KEEPING SOME CLOUD CVR AROUND ALL AREAS THROUGH SUNRISE. WED...MORE SIGNIFICANT S/W MOVES E FROM THE NRN PLAINS...ACRS THE GRT LAKES AND INTO ERN CANADA WED/WED NGT. MID/UPR LVL TROUGHING REALLY FLATTENS OUT SOUTH OF ABOUT 40-N LAT...SUGGESTING THAT MOST OF THE UPR SUPPORT FOR PRECIP WILL REMAIN WELL OFF TO OUR N. ALL MODELS DO SHOW A WEAKER/SHEARED OUT VORT MAX OUT TRACKING OUT AHEAD OF AND TO THE SOUTH OF THE MAIN TROUGH...PUSHING E OF THE APPALACHIANS BY 18Z. THIS FEATURE MAY SET OFF SOME WIDELY SCTD STORMS WED AFTN OVER OUR AREA. LOW LVL SW FLOW (DIRECTIONS 220-250) WOULD SUPPORT DEW PTS MIXING OUT INTO THE MID-UPR 50S DURING THE PEAK HEATING OF THE DAY. FOR THIS REASON...FAVOR THE LOWER SFC- BASED CAPES SHOWN BY THE NAM...CLOSER TO 1000 J/KG RATHER THAN THE 2000+ J/KG PER THE GFS (WHICH IS BASED OFF 65 F DEW PTS AT 18-00Z). EXPECT COVERAGE OF STORMS TO BE LMTD DUE TO THE DRIER LOW LVLS...AND WILL CONTINUE TO CAP POPS AT 20%-30% MOST AREAS WED AFTN...AND 30% MOST AREAS WED EVENG/NGT. LATEST SPC DAY 2 OUTLOOK HAS UPGRADED TO SLGT RISK...BUT FEEL THAT STORMS WILL BE WIDELY SCTD/POPS TOO LMTD FOR ANYTHING MORE THAN ISO SVR E OF THE MTNS IN AKQ CWA. SNDGS SHOW AN INVERTED-V PROFILE AND WILL HIGHLIGHT STRONG/GUSTY WINDS W/ CHC TSTMS IN HWO SHEAR IS UNIDIRECTIONAL/SW SO MAIN THREAT IS STRAIGHT LINE WINDS. THU...GOING WITH THE BNDRY MOVG S INTO CAROLINAS WITH HIGH BLDG IN FROM THE N. GFS KEEPS MSTR ACROSS SRN MOST CNTYS THRU MOST OF THE DAY BUT HAVE ELECTED TO ONLY HAVE SLGHT CHC POPS ACROSS NC CNTYS DRNG AM HRS. DRYER AIR FILTERS IN FROM THE N WITH A DECREASE IN CLDNS (PT TO M SUNNY) ACROSS NERN CNTYS. COOLER WITH HIGHS IN THE M60S N TO L70S S. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... THE LONG TERM PERIOD BEGINS THURSDAY NIGHT WITH HIGH PRESSURE ACROSS THE NORTHEAST AND A COLD FRONT DRAPED ACROSS THE CAROLINAS. UPPER RIDGING BEGINS TO EXPAND FRIDAY ACROSS THE SOUTHEAST AHEAD OF A TROUGH DIGGING OVER THE CENTRAL PLAINS PUSHING THE COLD FRONT BACK TO THE NORTH AS A WARM FRONT. MEANWHILE...SURFACE HIGH PRESSURE DRIFTS OFF THE COAST OF NEW ENGLAND MAINTAINING LOW-LEVEL EAST TO NORTHEAST FLOW ACROSS THE FORECAST AREA. THE WARM FRONT LIFTS THROUGH THE LOCAL AREA FRIDAY NIGHT. CHANCE POPS WERE MAINTAINED FOR THE FRIDAY/FRIDAY NIGHT PERIOD RATHER THAN INCREASING AS THE BEST SHORTWAVE ENERGY MOVES NORTH OF THE LOCAL AREA. MAXIMA FRIDAY ARE FORECAST TO BE IN THE UPPER 50S/LOW 60S FOR THE EASTERN SHORE...TO MID 60S SRN COUNTIES...BUT HIGHS COULD BE COOLER...ESPECIALLY INLAND DEPENDING ON CLOUD COVER AND PRECIPITATION. AN UPPER RIDGE THEN REMAINS ANCHORED OFF THE SOUTHEAST COAST THROUGH THE WEEKEND INTO EARLY NEXT WEEK. MODEL DIFFERENCES ARISE IN HOW FAR NORTH THE FRONTAL BOUNDARY EVENTUALLY SETTLES. THE GFS SUGGESTS UNSETTLED WEATHER...ESPECIALLY NORTH...WHILE THE ECMWF AND CMC SUGGEST PRIMARILY DRY CONDITIONS. AT THIS POINT CHANCE POPS WILL BE FORECAST NORTH...WITH SLIGHT CHANCE SOUTH. SOUTHERLY FLOW WILL GENERALLY PREVAIL THROUGH EARLY NEXT WEEK...ALTHOUGH A BACKDOOR FRONT COULD BRIEFLY DROP INTO THE EASTERN SHORE LATER SUNDAY INTO EARLY MONDAY. HENCE HIGH TEMPERATURES SHOULD REACH AT LEAST THE UPPER 70S/LOW 80S INLAND...WITH COOLER READING FOR THE EASTERN SHORE. && .AVIATION /10Z TUESDAY THROUGH SATURDAY/... VFR CONDS WILL PERSIST TODAY THROUGH WED WITH A BREEZY/GUSTY SW WIND DURING THE AFTERNOON HOURS. CHANCE FOR LWR CIGS/VSBYS WITH SHWRS/TSTMS LATE WED/ERLY THURS. && .MARINE... WILL RAISE SCA FLAGS FOR THE BAY (WINDS TO 20 KT) AND NRN COASTAL WATERS (MAINLY FOR 5 FT SEAS) STARTING AT NOON AS SLY FLOW INCREASES. S-SW FLOW WILL PERSIST OVER THE MARINE AREA THROUGH WEDNESDAY. THE WIND OVER THE BAY...AND SEAS OVER THE NRN COASTAL WATERS WILL LIKELY RETURN TO MARGINAL SCA CONDITIONS BY THIS AFTERNOON...AFTER A LULL THE REST OF THIS MORNING. A COLD FRONT APPROACHES FROM THE WEST DURING THE DAY WEDNESDAY AND THEN CROSSES THE REGION WEDNESDAY NIGHT INTO THURSDAY MORNING. HIGH PRESSURE MOVES ACROSS THE NORTHEAST THURSDAY AND TO THE NEW ENGLAND COAST FRIDAY BRINGING A PERIOD OF ONSHORE FLOW. && .HYDROLOGY... SENT UPDATED FLS STATEMENTS...RIVER HAS CRESTED AND IS NOW SLOWLY FALLING (NOW MINOR FLOODING RATHER THAN MODERATE AT WESTHAM). THE FLOOD WRNG CONTS ON JAMES RIVER AT RICHMOND WESTHAM AND THE CITY LOCKS...WILL LIKELY FALL BELOW FLOOD STAGE BY THIS EVENG. SEE WBCFLSAKQ FOR MORE INFORMATION. && .CLIMATE... WHILE RECORD HIGHS ARE NOT EXPECTED WED THERE IS AT LEAST AN OUTSIDE CHANCE FOR REACHING 90 DEGREES ON WED (APR 20TH). FOR REFERENCE...THE RECORD HIGHS ARE LISTED BELOW FOLLOWED BY CLIMATOLOGY FOR THE 1ST DATE WITH 90 DEGREE TEMPERATURES: RECORD HIGHS FOR WED 4/20: RIC...95 IN 1985 ORF...91 IN 1941 SBY...92 IN 1985 ECG...93 IN 1985 90-DEGREE CLIMATOLOGY: AVG 1ST DATE EARLIEST LATEST RICHMOND......MAY 11TH......MAR 17TH (1945)....JULY 2ND (1972) NORFOLK.......MAY 19TH......MAR 23RD (1907)....JULY 2ND (1972) && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...LKB