AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 240 PM EDT FRI JUL 8 2011 .SYNOPSIS... A FRONTAL BOUNDARY WILL REMAIN OVER THE AREA TODAY AS WEAK DISTURBANCES RIDE ALONG IT. THE FRONT WILL DRIFT SOUTH OF THE AREA FRIDAY NIGHT...AND REMAIN JUST SOUTH OF THE AREA THROUGH SATURDAY. HIGH PRESSURE WILL THEN BUILD IN FROM THE GREAT LAKES FOR THE WEEKEND...AND THEN SLIDE EAST ON MONDAY. A COLD FRONT WILL MOVE ACROSS ON TUESDAY...FOLLOWED BY CANADIAN HIGH PRESSURE FOR THE REST OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 200 PM UPDATE...SEVERE THUNDERSTORM WATCH IN EFFECT FOR ENTIRE REGION THROUGH 9 PM. MARGINAL TO MODERATE INSTABILITY...COMBINED WITH 35-40KT DEEP LAYER SHEAR AND APPROACHING SHORTWAVE ENERGY HAS SET THE ENVIRONMENT. HEAVY RAINFALL AND DAMAGING WINDS WILL BE MAIN THREAT WITH ANY SEVERE STORMS...WITH LARGE HAIL POSSIBLE IN ROTATING STORMS. 100 PM UPDATE...STATIONARY FRONT OVER THE FORECAST AREA IS SLOWLY SAGGING TO THE SOUTH. AIRMASS REMAINS FAVORABLE FOR SHOWER/TSTM DEVELOPMENT THIS AFTERNOON...WITH PW NEAR 2 INCHES...MAX SB CAPE LIKELY APPROACHING 2000 J/KG...ARRIVAL OF A MID LEVEL VORT MAX AND UPPER DIVERGENCE IN THE RIGHT REAR QUAD OF A JET STREAK PASSING TO THE NORTH. AN AXIS OF 35-40 KT BULK SHEAR HAS SET UP OVER THE REGION EARLY THIS AFTERNOON BASED ON SPC MESOANALYSIS. SPC HAS UPGRADED THE REGION TO A SLIGHT RISK OF SEVERE THUNDERSTORMS. PRIMARY THREAT WOULD BE DAMAGING WINDS...ALTHOUGH LARGE HAIL IS ALSO POSSIBLE. WITH LACK OF A DECENT SOUTHERLY LOW LEVEL JET OVERRIDING THE FRONT DO NOT THINK HEAVY RAIN THREAT WILL BE WIDESPREAD ENOUGH TO WARRANT A FLASH FLOOD WATCH...HOWEVER ANY STRONGER STORMS TODAY COULD DUMP A QUICK 1-2 INCHES OF RAIN. TEMPERATURE FORECAST REMAINS ON TRACK WITH HIGHS RANGING FROM THE UPPER 70S OVER NORTHERN INTERIOR SECTIONS TO THE MID 80S OVER THE NYC METRO. A FEW SPOTS OVER NE NJ MAY REACH THE UPPER 80S. THERE IS A MODERATE RIP CURRENT RISK AT THE OCEAN BEACHES TODAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... THE FRONT WILL DROP S THROUGH THE AREA TONIGHT AS A WEAK LOW RIDES ALONG IT AND QUICKLY MOVES INTO THE OFFSHORE WATERS S OF LONG ISLAND BY SATURDAY MORNING. CHANCE/LIKELY POP THIS EVENING WILL GRADUALLY TAPER OFF OVERNIGHT. LOWS IN THE 60S TO LOWER 70S EXPECTED. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... CANADIAN HIGH PRESSURE BUILDS OVER THE REGION ON SUNDAY WITH SW WARM ADVECTION AND HUMIDITY RETURNING ON MONDAY. DEWPOINTS OF AROUND 60 ON SUNDAY RISE TO UPPER 60S ON MONDAY AS MARITIME TROPICAL AIR RETURNS ONCE AGAIN. KEPT IT DRY ON MONDAY...AS INSTABILITY IS LIMITED AND SUBSIDENCE ALOFT SHOULD SUPPRESS ANY DIURNALLY DRIVEN CONVECTION. MAIN WEATHER EVENT FOR THE LONG TERM PERIOD IS A COLD FRONT THAT ORIGINATES WITH SHORTWAVE CURRENTLY OVER BRITISH COLUMBIA. EXAMINATION OF THE 12Z AND 18Z GEFS WITH AGREEMENT FROM THE 12Z ECMWF AND LATEST GEM ALL SUPPORT COLD FRONTAL PASSAGE TUESDAY. HAVE FOCUSED PCPN CHANCES FOR THE DIURNALLY FAVORED AFTERNOON PERIOD. EARLY ESTIMATES OF CAPE FOR TUESDAY AFTERNOON ARE MODERATE AT AROUND 2000 J/KG WITH WEAK TO MODERATE SHEAR OF 30-35 KT IN THE 0-6 KM LAYER. SO HAVE SOME POTENTIAL FOR SEVERE DEPENDING ON THE TIMING OF THE FRONT. NOTE...THIS DIFFERS FROM PREVIOUS FORECASTS...THOUGH WITH SUPPORT FROM THE GLOBAL ENSEMBLES AND DETERMINISTIC RUNS...CONFIDENCE IS HIGH ENOUGH TO DEVIATE FROM CONTINUITY AT THIS TIME. HIGH PRESSURE AND LOW HUMIDITY RETURN FOR WEDNESDAY THROUGH THE END OF THE WEEK. TEMPS ARE FCST BASED ON LATEST MOS AND WARM TO SLIGHTLY ABOVE NORMAL ON MONDAY. MONDAY AND TUESDAY SHOULD SEE LOWER 90S FOR NE JERSEY...AND APPROACHING 90 IN NYC. THE HIGH DEW POINT TEMPERATURES RESULTS IN HEAT INDEX VALUES IN THE LOWER AND MID 90S FOR THESE AREAS. COMFORTABLE MID SUMMER WEATHER RETURNS ON WEDNESDAY WITH LOWER 80S FOR MAXES AND DEW POINT TEMPS IN THE MID 50S. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... A WEAK FRONT WASHES OUT OVER THE REGION THIS AFTERNOON...WITH WAVES OF LOW PRESSURE MOVING SOUTH OF THE REGION TONIGHT. GENERALLY VFR CONDS EXPECTED THROUGH THIS AFTERNOON ACROSS WESTERN TERMINALS...EXCEPT IN SHRA/TSRA. PATCHY IFR/MVFR CIGS ACROSS COASTAL TERMINALS WITH BANDS OF MARINE STRATUS/FOG PARTIALLY EVIDENT. STRATUS/FOG MAY BECOME MORE WIDESPREAD ACROSS EASTERN TERMINALS THAN DEPICTED THIS EVENING IF CONVECTION DOES NOT MATERIALIZE. CONVECTIVE COVERAGE INCREASING JUST WEST OF THE TERMINALS...AND EXPECT IT TO BE FAIRLY WIDESPREAD BY 20-22Z ACROSS WESTERN TERMINALS...MOVING INTO EASTERN TERMINALS THIS EVENING. EXPECT WIDESPREAD CONVECTION TO COME TO AN END TONIGHT FROM NW TO SE. WILL BE AMENDING TAFS TO GIVE MORE PRECISE TIMING ON CONVECTION. WITH ANY STRONGER STORM LOCALIZED MVFR-IFR CONDITIONS ARE POSSIBLE IN HEAVY RAINS. DAMAGING WINDS AND LARGE HAIL POSSIBLE AS WELL. ALL TERMINALS ARE UNDER A SVR TSTSM WATCH TIL 9PM. CCFP CONFIDENCE/COVERAGE LOOKS GOOD. WIND GENERALLY FROM A LIGHT ESE THIS AFTERNOON INTO EVENING AHEAD OF WAVE...BECOMING LIGHT N LATE TONIGHT. MVFR STRATUS/FOG LIKELY ACROSS EASTERN TERMINALS AND POSSIBLY ACROSS WESTERN TERMINALS IN LIGHT WINDS AND ABUNDANT LOW-LEVEL MOISTURE LATE TONIGHT. CONDS IMPROVING TO VFR SATURDAY MORNING...IN NW FLOW. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: AMENDMENTS LIKELY TO REFLECT THUNDERSTORMS. KLGA FCSTER COMMENTS: AMENDMENTS LIKELY TO REFLECT THUNDERSTORMS. KEWR FCSTER COMMENTS: AMENDMENTS LIKELY TO REFLECT THUNDERSTORMS. KTEB FCSTER COMMENTS: AMENDMENTS LIKELY TO REFLECT THUNDERSTORMS. KHPN FCSTER COMMENTS: AMENDMENTS LIKELY TO REFLECT THUNDERSTORMS. KISP FCSTER COMMENTS: AMENDMENTS LIKELY TO REFLECT THUNDERSTORMS. OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY... SATURDAY MORNING...BECOMING VFR. SATURDAY AFTERNOON-MONDAY...VFR. MONDAY NIGHT-TUESDAY...CHANCE OF MVFR OR LOWER LATE MONDAY NIGHT/TUESDAY MORNING WITH LOW STRATUS/FOG...THEN SUB-VFR POSSIBLE WITH SHRA/TSRA LATER IN THE DAY AHEAD OF A COLD FRONT. WEDNESDAY...VFR. && .MARINE... GENERALLY QUIET WITH RESPECT TO WINDS/WAVES...BUT CONVECTION COULD PRODUCE LOCALLY GUSTY WINDS AND REDUCED VSBY THIS AFTERNOON INTO THIS EVENING. S SWELL GENERATED BY HIGH PRESSURE OFF THE S COAST WILL SPREAD NORTHWARD TODAY INTO SAT...AND WAVEWATCH INDICATES 5 FT OCEAN SEAS POSSIBLE SAT AFTERNOON. AT THIS TIME EXPECT CURRENT 7 FT SEAS OFF THE NC COAST TO DECAY TO JUST UNDER 5 FT BEFORE THEY REACH OUR COASTAL WATERS. INCREASING S FLOW AHEAD OF A COLD FRONT MAY AGAIN BUILD OCEAN SEAS TO NEAR 5 FT ON TUE. && .HYDROLOGY... HEAVY RAINFALL OF 1-2 INCHES IS POSSIBLE TODAY INTO THIS EVENING WITH ANY STRONGER CONVECTION...WHICH WOULD CAUSE LOCALIZED URBAN/POOR DRAINAGE FLOODING. SMALL STREAM FLOODING MAY ALSO BE POSSIBLE IN NORTHEAST NJ IF RAINFALL OF THIS MAGNITUDE FALLS IN AN HOUR OR LESS. THE OVERALL THREAT DOES NOT LOOK TO BE WIDESPREAD ENOUGH TO WARRANT A FLASH FLOOD WATCH. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...GOODMAN/JST