Area Forecast Discussion
Issued by NWS Upton, NY

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950 FXUS61 KOKX 271946 AFDOKX Area Forecast Discussion National Weather Service New York NY 346 PM EDT WED JUL 27 2016 .SYNOPSIS...
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Weak high pressure tonight will give way to an approaching cold front Thursday. A wave of low pressure approaches and passes nearby Friday. This low moves east of the region Friday night. Weak high pressure briefly builds into the region for Saturday. Unsettled weather returns for the end of the weekend and start of next week with the passage of another low pressure system. Drier weather is expected for Tuesday and Wednesday as high pressure returns.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Aloft, upper trough moves across the upper Great Lakes region. A surface cold front accompany this features moves well to the north. Meanwhile, another weak frontal boundary remains to our south, with a series of weak lows along it. Weak high pressure remains offshore, and a light south flow prevails across the region. Dew points increase slightly, and as temperatures fall tonight under mostly clear skies, patchy fog formation is possible as boundary layer begins to saturate. Not quite sure of extent of any fog, but it is possible as hinted at by the models. Lows tonight will range from around 60 well inland, to the middle 70s in NYC metro. Followed a mos and model blend.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
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Through this time period, upper trough axis extending south across the great lakes region/Ohio Valley and into the upper Mississippi Valley will move east, with embedded Vorts in the mid and upper level flow tracking east. Frontal boundary to the south remains Thursday, as a series of low pressure centers ride along it, the strongest of which approaches Thursday night and Friday. Better jet support Friday, and enhanced lift along with abundant moisture advecting east/northeast will allow for rain/possibly heavy Friday. Prior to that, isolated thunder per high resolution models develops along seabreeze boundary Thursday afternoon. Kept pops in slight chance range as coverage should be isolated, and this assumes ample moisture up the column materializes. One more warm to hot day is expected Thursday, with highs in the upper 80s to around 90 under partly sunny skies. With higher humidity levels, heat indices will run a degree or two above actual air temps. Temps will remain seasonably warm Thursday night, and not quite as much of a range is expected as clouds increase, and rain chances increase. With the passage of a wave of low pressure, possibly just to our south, temperatures on Friday will be cooler, upper 70s to around 80 thanks to clouds and rain. This has trended lower than previous forecast.
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&& .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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Low pressure moving across the region moves east Friday night, with just some left over showers and possibly a thunderstorm. Weak high pressure briefly returns on Saturday, with most of the forecast guidance keeping conditions dry. As a result, will keep conditions dry on Saturday. Unsettled weather returns Saturday night into Monday, as another shortwave and low pressure system moves across the region. Expect another round of showers and thunderstorms, with some storms producing locally heavy rainfall. High pressure builds back into the region early next week, providing dry conditions. Temperatures will remain seasonable Saturday through Wednesday with temperatures climbing into the 80s each day.
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&& .AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
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VFR with a weak S/SW flow through Thursday with local seabreeze enhancements. Latest radar data and surface observations show seabreeze over KLGA, but still southeast of KEWR. Deep mixing today is waging a battle between the westerly flow across the interior and the seabreeze front. It may take another 1-3 hours to pass through KTEB, KEWR, and KHPN when the airmass cools just enough to allow for a weaker westerly flow to mix down to the surface. There is a low probability of MVFR/IFR cigs late tonight at the coastal terminals. Preference at this time is to remain VFR. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: No unscheduled amendments expected. KLGA TAF Comments:High probability in southerly seabreeze developing in the next 1-2 hours. KEWR TAF Comments: Moderate probability of SE seabreeze this afternoon, with most likely timing of onset between 21z and 23z. KTEB TAF Comments: Moderate probability of SSE seabreeze this afternoon/early evening...with most likely timing of onset between 21z and 23z. KHPN TAF Comments: Moderate probability of seabreeze by late afternoon, from 21Z to 23Z. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... .Thursday Afternoon...VFR. Isolated showers and thunderstorms possible, mainly NW of the NYC terminals. .Thursday Night into Friday Night...MVFR or lower possible in showers and thunderstorms, possibly widespread. Patchy fog. .Saturday...VFR. .Saturday Night into Monday...Iso-Sct shra/tsra possible.
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&& .MARINE...
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As a weak front approaches, and weak wave of low pressure moves by Thursday night and Friday, expect sub SCA conditions to continue across the area waters. A light pressure gradient over the area waters will result in sub- sca conditions this weekend and early next week. However, any thunderstorms that develop on the waters may produce brief SCA conditions.
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&& .HYDROLOGY...
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There is potential for significant rainfall from late Thursday night into Friday night. Locally heavy rainfall is possible, which could cause flooding. Exact evolution of this potential storm remains unclear, so it remains too early for specifics.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...BC/PW NEAR TERM...PW SHORT TERM...PW LONG TERM...BC AVIATION...DW MARINE...BC/PW HYDROLOGY...BC/PW

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