Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 211641 AFDOKX Area Forecast Discussion National Weather Service New York NY 1241 PM EDT Sat Oct 21 2017 .SYNOPSIS... Mild weather continues through the weekend. A cold front brings rain to the region on Tuesday that may linger into Wednesday as temperatures cool. High pressure builds back in by late in the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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The forecast is mostly on track. Minor adjustments to hourly temperatures and dewpoints were made to capture the latest trends. Sunshine will be filtered through some cirrus from time to time. Warm and dry conditions as high temperatures average mostly in the mid to upper 70s, and a few 80 degree readings possible in the city and urbanized areas of NE NJ. This is about 15 degrees above average, but short of record values. Islip still has a chance to tie or break the record of 76 set last year. An oncoming sea breeze may stop that from happening however.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... Cirrus starts to increase on Sunday and we`re partly to mostly cloudy on Monday as warm advection increases aloft. Max temps lower slightly due to the cloud cover, but still well above seasonable. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Well, it sure appears that it will actually rain! Analysis of the 00Z GEFS suggests cold FROPA consensus timing is focused on Tuesday Evening in the local area as a rather potent cyclone occludes over the Great Lakes. Note that the ECMWF deterministic run suggest a slightly slower and prolonged passage. The GFS BUFR wind data has impressed me with the narrow cold frontal rain band. Standardized anomalies and the ensemble situational awareness table indicate +3 Standard Deviation in the 925 hPa southerly winds in the GEFS with the deterministic GFS run getting up to +5 or more. Thus, the threat for at least wind advisory (Gust 40+ KT) criteria is increasing - especially for Long Island and Southern CT. Did remove the thunder from the forecast as there`s no cape and all indices do not support it. Beyond Tuesday night, uncertainty is high as for how much, if any rain we get Wednesday. the majority of the GEFS members keep the rain offshore. The local forecast is trending this direction. Temperatures average above normal through the period with Thursday being closest to normal. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... VFR expected through the TAF period as high pressure builds overhead today, then moves east tonight. Light northerly winds become S/SW less than 10 kt in the afternoon. There is a low chance of MVFR to IFR stratus and/or fog late tonight at KSWF/KHPN/KGON. .OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY... .Sunday...VFR. .Sunday night-Monday...MVFR/IFR possible in stratus and fog. .Tuesday...MVFR possible in showers. S wind G20-30 KT at coast. LLWS possible. .Wednesday...VFR. A chance of showers with areas of MVFR, especially early. && .MARINE... Sub-advsy conds will prevail on the waters into at least Mon night. The pressure gradient will begin to tighten late Mon night between high pressure to the east and strengthening low pressure to the west. SCA conds are expected to develop on Tue, with gale force winds possible late Tue and Tue night as there is the potential for a 50-60kt LLJ at 950mb. There is uncertainty with the strength and track of the low, so wind forecast does not reflect this potential yet, but have increased the gusts from previous forecast. Will also mention the gale potential in the HWO. Winds begin to subside Tue night, although the GFS is faster than the EC, so may be bringing them down a bit too quick. Seas will likely remain above SCA levels on the ocean waters through Wed night. && .HYDROLOGY... No hydrologic problems are expected the next 7 days. Rain with cold frontal passage late Tuesday should average near 1". && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...Tongue NEAR TERM...JC/Tongue SHORT TERM...Tongue LONG TERM...Tongue AVIATION...24/NV MARINE...24 HYDROLOGY...Tongue

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