AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 200 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 IS EXPECTED TO GRADUALLY SINK SOUTH OF THE TERMINALS THIS AFTERNOON...AND THEN HOLD S OF LONG ISLAND. WAVES OF LOW PRESSURE WILL MOVE NE ALONG THE FRONT THROUGH TONIGHT. COMPLEX FORECAST TODAY. GENERALLY VFR CONDS EXPECTED THROUGH THIS AFTERNOON ACROSS WESTERN TERMINALS...EXCEPT IN SHRA/TSRA. ACROSS COASTAL TERMINALS...ALTHOUGH CONDS ARE IMPROVING...AN AREA OF MARINE STRATUS/FOG IS WORKING ITS WAY TOWARDS S COASTAL LI. EXPECTING IFR CIGS TO DEVELOP OVER THE NEXT HOUR OR SO AT KJFK AND THEN LIKELY WORKING INTO KISP BY EARLY AFTERNOON. QUESTION IS HOLD LONG THIS WILL PERSIST AND HOW FAR NORTH IT ADVECTS...PARTICULARLY IF FRONT SAGS SOUTH. WILL CONTINUE TO MONITOR. AS FAR AS CONVECTION FOR TODAY GOES...ISOLD CONVECTION THROUGH EARLY AFTERNOON. THEN INCREASING COVERAGE EXPECTED ACROSS WESTERN TERMINALS AFTER 17-19Z AS SHORTWAVE APPROACHES THE REGION. EXPECT WIDESPREAD CONVECTION TO COME TO AN END TONIGHT FROM NW TO SE. CCFP OF HIGH CONFIDENCE BUT SPARSE COVERAGE LOOKS GOOD AFTER 19Z. AT THIS POINT STILL TOO MUCH UNCERTAINTY TO PINPOINT WHEN TSRA WILL BE AT ANY GIVEN TERMINAL SO JUST REFLECT POTENTIAL W/CB GROUP. WITH ANY STRONGER STORM LOCALIZED MVFR-IFR CONDITIONS ARE POSSIBLE ALONG WITH GUSTY WINDS. FOR NOW IT APPEARS THAT THE BEST CHANCE FOR THE STRONGEST CONVECTION AT THE CITY TERMINALS WOULD BE FROM AROUND 22-05Z. WITH WEAK FRONTAL BOUNDARY MOVING TO S...AND WEAK WAVES OF LOW PRESSURE MOVING ALONG IT...WIND DIRECTION WILL BE HIGHLY VARIABLE TODAY FROM NE TO SW...BUT SPEEDS SHOULD GENERALLY BE AT OR BELOW 6 KT. EXCEPTION IS KLGA/KJFK/KISP/KBDR THIS AFTERNOON WHICH COULD SEE SPEEDS JUST ABOVE 6 KT...USED A ESE-SE DIRECTION AT THOSE TERMINALS...BUT COULD BE ANYTHING FROM E TO S. WINDS BECOME LIGHT AND VARIABLE THIS EVENING AT ALL TERMINALS. 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 POSSIBLE TO REFLECT THUNDERSTORMS...AS WELL AS TIMING FOR IFR STRATUS ADVECTING ONSHORE. KLGA FCSTER COMMENTS: AMENDMENTS POSSIBLE TO REFLECT THUNDERSTORMS. KEWR FCSTER COMMENTS: AMENDMENTS POSSIBLE TO REFLECT THUNDERSTORMS. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: AMENDMENTS POSSIBLE TO REFLECT THUNDERSTORMS. LOW CHANCE FOR SUB-VFR CEILINGS WITH SHRA/ISOLD TSRA THIS MORNING. KHPN FCSTER COMMENTS: AMENDMENTS POSSIBLE TO REFLECT THUNDERSTORMS. KISP FCSTER COMMENTS: AMENDMENTS POSSIBLE TO REFLECT THUNDERSTORMS...AS WELL AS TIMING FOR IFR STRATUS ADVECTING ONSHORE. OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY... 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. && .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