Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 311643 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1243 PM EDT THU JUL 31 2014 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OFF THE NORTHEAST COAST THROUGH FRIDAY WHILE WEAK DISTURBANCE MOVES THROUGH THE REGION. A FRONTAL BOUNDARY WILL BACK IN FROM THE OCEAN THIS WEEKEND AND IMPACT THE AREA THROUGH THE BEGINNING OF THE WEEK. HIGH PRESSURE THEN BUILDS INTO THE REGION. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... SFC HIGH PRES REMAINS OVER THE MID-ATLANTIC...AND WEAK SHORTWAVE IN THE MIDDLE LEVELS OF THE ATMOSPHERE CONTINUES TO WORK ITS WAY NORTH OF THE REGION. ML MUCAPE VALUES ARE AVERAGING 500-750 J/KG ACROSS MOST OF THE REGION...AND ARE TOPPING 1000 J/KG ACROSS NORTHERN PORTIONS OF THE LOWER HUDSON VALLEY. THERE IS ALSO 30-40 KT OF 0-6 KM BULK SHEAR ACROSS THE REGION. HOWEVER...THERE IS LITTLE LIFT IN THE ATMOSPHERE AS MOST OF THE ENERGY REMAINS NORTH OF THE REGION. WILL GO AHEAD AND DROP BACK POPS BY ABOUT 10-15 PERCENT...DROPPING POPS FROM CHANCE TO SLIGHT CHANCE FOR MOST OF THE WESTERN HALF OF THE CWA AND WILL DROP POPS FOR FAR SE CT AND EASTERN SUFFOLK COUNTY. MAX TEMPS TODAY TOPPING OFF IN THE UPPER 70S TO LOW 80S WITH THE WARMEST TEMPS ACROSS NYC AND NE NJ. THERE REMAINS A MODERATE RISK FOR RIP CURRENTS THIS AFTERNOON WITH AFTERNOON SEABREEZE DEVELOPMENT AND 3 FT S/SE SWELLS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... ANY SHOWER ACTIVITY WILL TAPER OFF IN THE EVENING. TEMPS NEAR SEASONABLE AS MOISTURE LEVELS GRADUALLY INCREASE WITH LIGHT ONSHORE FLOW...GENERALLY IN THE 60S. PATCHY FOG POSSIBLE ACROSS OUTLYING AREAS AS A RESULT. DEEP TROUGHING ACROSS EASTERN 1/2 OF THE US...DEEPENS SOUTHERLY FLOW UP THE EAST COAST. INCREASING MOISTURE/INSTABILITY ALONG WITH SOUTHERN STREAM SHORTWAVE ENERGY RIDING UP THE COAST AND WEAK RIGHT REAR JET LIFT WILL PRESENT A BETTER CHANCE FOR DIURNAL SHRA/TSRA ACTIVITY FOR NYC METRO AND PARTICULARLY POINTS N&W FRI AFT/EVE. OVERALL SHEAR LOOKS WEAK...SO WOULD EXPECT CONVECTION TO BE MORE PULSE IN NATURE...BUT CANT RULE OUT A FEW STRONG STORMS. 15 KT SSE STEERING FLOW WILL LEND TO AN URBAN/POOR DRAINAGE FLOOD POTENTIAL. TEMPS NEAR SEASONABLE IN MODERATING AIRMASS...LOWER 80S TO 85. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... DEEP UPPER TROUGH REMAINS TO THE EAST OF THE AREA FRIDAY NIGHT ALONG WITH A STRONG WESTERN ATLANTIC HIGH PRESSURE AREA. AS THE HIGH RETROGRADES WEST...IT WILL PUSH A FRONT TO THE WEST WITH IT. WITH THE BLOCKING PATTERN IN PLACE DUE TO THE UPPER LOW TO THE WEST...THE FRONT WILL SIT NEAR AND/OR OVER THE AREA THROUGH THE WEEKEND. A CONTINUOUS SOUTH-SOUTHWEST FLOW WILL ALSO HELP BRING SUFFICIENT MOISTURE INTO THE AREA. THE RIGHT ENTRANCE REGION OF AN UPPER JET ALSO SITS OVER THE REGION THROUGH THE WEEKEND. A COMBINATION OF THESE WILL KEEP UNSETTLED AND SHOWERY CONDITIONS OVER THE AREA. SOME OF THE SHOWERS/THUNDERSTORMS COULD PRODUCE MODERATE TO HEAVY RAINFALL. 12Z ECMWF IS A WETTER SOLUTION WITH THE FRONT SETTING UP ACROSS THE AREA WHILE THE GFS/NAM KEEPS IT TO THE SOUTH WHICH KEEPS THE AREA DRY THROUGH SUNDAY MORNING. WITH SO MUCH UNCERTAINTY REMAINING...DID NOT MAKE ANY MAJOR CHANGES TO THE POP GRIDS AND LEFT CHANCE FOR MUCH OF THE AREA SATURDAY AND SUNDAY. TEMPERATURES THROUGH THE WEEKEND WILL BE NEAR NORMAL...MAYBE SLIGHTLY BELOW NORMAL FOR HIGHS. WITH INCREASING DEW POINTS DUE TO THE MULTIPLE NIGHTS OF SOUTHERLY WIND...HAVE ADDED PATCHY FOG FOR SUNDAY AND MONDAY NIGHTS. A SURFACE LOW THEN DEVELOPS OVER THE SE IN RESPONSE TO THE DEEP UPPER TROUGH. THIS QUICKLY TRACKS NE OVER THE LOCAL AREA ON MONDAY. ECMWF FLATTENS THE UPPER LEVELS QUICKER ON MONDAY WHILE THE GFS LEAVES THE SURFACE LOW LINGERING ACROSS THE NORTHEAST WITH A WET SUNDAY AND MONDAY. AGAIN...WILL MAKE NO MAJOR CHANGES TO THE POP FORECAST. DRY WEATHER THEN EXPECTED TUES AND WED. TEMPS WILL BEGIN TO WARM MON-WED AS HEIGHTS RISE A FEW DEGREES WITH MORE BREAKS IN THE SUN THAN THE WEEKEND. LOWS WILL REMAIN NEAR NORMAL. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... HIGH PRESSURE WILL REMAIN OFFSHORE INTO FRIDAY MORNING. MOST LIKELY VFR THROUGH THE TAF PERIOD. ISOLD-SCT SHRA WITH POSSIBLY SOME EMBEDDED THUNDER ARE POSSIBLE THIS AFTERNOON...MAINLY TO THE N/W OF NYC. PROBABILITY OF OCCURRENCE AT ANY GIVEN TERMINAL IS TOO LOW TO REFLECT IN THE TAFS AT THIS TIME...EXCEPT FOR KSWF WHERE SHRA HAVE BEEN RETAINED IN A TEMPO GROUP. SHRA/TSTMS...IF ANY...DECREASE IN INTENSITY AND COVERAGE AFT 22Z. SW WINDS VEER TO THE S AND INCREASE INTO THE AFTERNOON WITH A SEABREEZE COMPONENT. SPEEDS LIGHTEN AGAIN TONIGHT AS THE SEABREEZE INFLUENCE WEAKENS. 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: TIMING OF START/END OF GUSTY WINDS COULD BE OFF +/- 1-2 HOURS. KLGA FCSTER COMMENTS: TIMING OF START/END OF GUSTY WINDS COULD BE OFF +/- 1-2 HOURS. KEWR FCSTER COMMENTS: TIMING OF START/END OF GUSTY WINDS COULD BE OFF +/- 1-2 HOURS. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: TIMING OF START/END OF GUSTY WINDS COULD BE OFF +/- 1-2 HOURS. KHPN FCSTER COMMENTS: TIMING IN CHANGES IN WIND DIRECTION/SPEED COULD BE OFF +/- 1-2 HOURS. KISP FCSTER COMMENTS: TIMING IN CHANGES IN WIND DIRECTION/SPEED COULD BE OFF +/- 1-2 HOURS. .OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY... .FRIDAY-FRIDAY NIGHT...MAINLY VFR. ISOLD SHRA/TSTMS POSSIBLE IN THE AFTERNOON/EVENING. .SATURDAY-SUNDAY NIGHT...AREAS OF MVFR OR LOWER POSSIBLE. .MONDAY...BECOMING VFR. && .MARINE... WITH HIGH PRES OVER THE WATERS...CAN EXPECT SUB-SMALL CRAFT ADVISORY CONDITIONS THROUGH FRIDAY. WINDS AND SEAS WILL CONTINUE TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FRIDAY NIGHT-MONDAY. && .HYDROLOGY... NO SIGNIFICANT RAINFALL IS EXPECTED THROUGH TONIGHT. LOCALLY HEAVY DOWNPOURS IN SCATTERED TSTMS ON FRIDAY WILL PRESENT MAINLY A URBAN/POOR DRAINAGE FLOOD THREAT DUE TO AROUND 15 KT MOVEMENT...WITH A LOW AND LOCALIZED FLASH FLOOD THREAT WITH ANY TRAINING OF CELLS. AN INCREASINGLY MOIST AIR MASS WILL BE CONDUCIVE TO THE DEVELOPMENT OF HEAVY SHOWERS THIS WEEKEND. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...NV NEAR TERM...MPS/NV SHORT TERM...NV LONG TERM...LN AVIATION...JMC/MALOIT MARINE...LN/NV HYDROLOGY...LN/NV

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