Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 271608 AFDOKX Area Forecast Discussion National Weather Service New York NY 1208 PM EDT WED JUL 27 2016 .SYNOPSIS... Weak high pressure will remain through tonight, then weaken on Thursday. A weak cold front will approach Thursday night, and remain nearby into the weekend as a few waves of low pressure pass nearby. High pressure will return early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Made some minor adjustments to temps and dewpoints to reflect current observations. Otherwise, expect sunny skies into the early afternoon, then high clouds mainly this afternoon as a mid level shortwave approaches in zonal flow aloft. High temps should be a shade hotter this afternoon than those of yesterday inland, still mostly lower 90s, while coastal sea breezes cap temps in the upper 80s along the south shore of Long Island and SE CT. Heat indices should be close to ambient temps for the most part via lower dewpoints in the lower 60s, but afternoon sea breezes bringing in more humid marine air with dewpoints in the upper 60s could boost heat indices right along the coast to just above ambient temps. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... Expect mostly clear skies tonight as the aforementioned shortwave passes by. GFS tries to produce some light precip in association with this wave, but this does not look realistic as the air mass in place should still be fairly dry and stable. Low temps will be close to or slightly warmer than those expected for early this morning, in the 70s invof NYC and across western Long Island, and in the 60s elsewhere. Thu looks like another hot and increasingly humid day, with high temps in the lower 90s for NYC metro and inland sections, and upper 80s near south facing shores. Dewpoints increasing to the upper 60s to near 70 from NYC metro east should push heat index values into the mid/upper 90s in those areas, with lower 90s elsewhere. Zonal flow aloft turns a little more SW through the day on Thu, and the combo of an approaching mid level shortwave and convergence invof a weak inland thermal trough and along sea breeze boundaries should spark at least isold convection. The 00Z SBU NAM/GFS WRF and the NCAR ensemble are all signaling more focused development along the sea breeze in NYC metro and across Long Island where greater instability will also reside, as increasing dewpoints push MLCAPE to 1000-1500 J/kg across Long Island and 500-1000 J/kg most elsewhere, so have scattered PoP for those areas in the afternoon. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... A low pressure system will move from the Mid-Atlantic northeastward Thursday night into Friday night, resulting in showers and thunderstorms across the area. There is the potential for locally heavy rainfall with precipitable water values in excess of 2 inches. As the wave of low pressure departs, there may be a break in the precipitation Saturday, but isolated to widely scattered showers cannot be ruled out. More unsettled conditions are possible Saturday night into Sunday, as another potential short wave moves through. Will continue mention of chance pops due to model differences at this time. High pressure builds in from Canada early next week. Temperatures look to be near seasonable levels Friday into early next week. && .AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
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High pressure builds offshore through tonight. VFR through the period. Light and variable winds back to the W/WSW across the inland terminals early this afternoon with the seabreeze propagating slowly north across the coastal terminals. Latest analysis has the seabreeze just north of KISP and KJFK. Have moved up the timing at KLGA and KEWR by 1-2 hours based on latest position and movement. Greatest uncertainty is with the extent of the seabreeze influence at KTEB and KEWR as winds try to back to the SSE. Winds diminish to light S/SW flow tonight. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ KJFK TAF Comments: No unscheduled amendments expected. KLGA TAF Comments: NE winds likely through 17z. High probability in southerly seabreeze this afternoon, with most likely timing of onset between 18z and 19z. KEWR TAF Comments: Moderate probability of SE seabreeze this afternoon, with most likely timing of onset between 19z and 21z. Seabreeze may waver near the airport for a few hours this afternoon, before passing through. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Moderate probability of SSE seabreeze this afternoon...with most likely timing of onset between 20z and 22z. Sea breeze may waver near the airport for a few hours this afternoon, before passing through. KHPN TAF Comments: Moderate to high probability of seabreeze by late afternoon. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY... .Thursday...VFR. Isolated showers and thunderstorms possible Thursday afternoon, mainly NW of the NYC terminals. .Thursday Night into Friday Night...MVFR or lower possible in showers and thunderstorms. Patchy fog. .Saturday into Sunday...Iso-Sct diurnal shra/tsra possible.
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&& .MARINE... Sub-SCA conditions will prevail through the weekend. High pressure builds, then gives way to waves of low pressure late this week and weekend. && .HYDROLOGY... There is potential for significant rainfall from late Thursday night into Friday night. Locally heavy rainfall is possible, which could cause flooding. It is still too early for specifics. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...FIG/Goodman NEAR TERM...Goodman/PW SHORT TERM...Goodman LONG TERM...FIG AVIATION...NV/DW MARINE...FIG/Goodman/PW HYDROLOGY...FIG/Goodman is the U.S. government's official web portal to all federal, state and local government web resources and services.