Area Forecast Discussion
Issued by NWS Upton, NY

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037 FXUS61 KOKX 081718 AFDOKX Area Forecast Discussion National Weather Service New York NY 1218 PM EST Thu Dec 8 2016 .SYNOPSIS... A series of cold fronts cross the area Thursday through Friday. High pressure builds through Saturday. Low pressure and associated front impacts the area later Sunday and Monday. High pressure returns Tuesday. Another front approaches Wednesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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17Z Update - Forecast remains on track with little change to database. Still expecting Jet`s associated thick mid/high clouds to dissipate/move out late this afternoon as a shortwave passes. The shortwave moves through dry, however it provides a shot of cold air advection that increases winds out of the northwest by late afternoon. Temperatures expect to fall slowly through the mid to late afternoon north and west of NYC. Used a MAV/MET/ECS blend for temperatures, which looked fairly reasonable.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
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Another shortwave moves across the region Thursday night into Friday, providing yet another shot of cold air. In addition, there should be enough moistening of the low and mid levels early Friday morning to warrant a slight chance of snow showers. The best chances of any precipitation will remain north and west of NYC, however by mid to late morning, snow showers will be possible across the entire CWA. little to no accumulations are expected with these snow showers. Low temperatures Thursday night will fall into 20s and lower 30s. A gusty northwest flow 20-30 mph will allow wind chills to reach the teens and lower 20s around sunrise Friday morning. High temperatures on Friday will only reach the middle and upper 30s, but will feel like 20s, as the gusty northwest flow continues.
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&& .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Uncertainty due to differences in details this time frame in a progressive flow through the weekend, then a more amplified pattern mid week next week. Chilly air settles in from Canada through much of this time period, and timing of individual systems remains a challenge. Generally expect dry weather Friday night and Saturday as initial shortwave departs, and surface high pressure builds to the south. Next impulse and surface boundary approaches from the west Sunday with potential for WAA precip (likely snow) developing later Sunday and Sunday night. On Monday, track and strength of low pressure is unclear, but frontal boundary looks to remain south of the area. Will maintain likely PoP for this timeframe since models agree on precip, if not overall pattern details. P-type will be tricky late Sunday night and Monday, with some mix or changeover likely as warmer air advects northward. This upper shortwave races east by Tuesday, along with low pressure and front, although 00Z ECMWF shows lingering Norlun type trough nearby or just east of the area early Tuesday between inland weakening low and offshore low. More vigorous upper trough begins to take shape, tracking across the upper mid west and pivoting across the Great Lakes region by mid week. Latest GFS and ECMWF runs differ on depth of this trough, and sfc features. This leads to overall lower confidence in forecast day 7. Temperatures should remain at or just below normal through much of this period. Brief warmups could occur in WAA ahead of each shortwave/low pressure in return flow. && .AVIATION /17Z THURSDAY THROUGH MONDAY/...
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A cold front passes this afternoon. High pressure then builds through Friday. VFR through the TAF period. W-WNW winds continue through tonight. Gusty winds will continue to develop this afternoon, before relaxing somewhat overnight. Gusts could become more occasional overnight, especially at outlying terminals. Winds and gusts will increase after sunrise tomorrow with gusts 25 to 30 kt late morning into the afternoon. 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: Gusts may begin 1-2 hours later than forecast. Wind direction will stay left of 310 magnetic through this evening. KLGA TAF Comments: Gusts may begin 1-2 hours later than forecast. Wind direction will stay left of 310 magnetic through this evening. KEWR TAF Comments: Gusts may begin 1-2 hours later than forecast. Wind direction will stay left of 310 magnetic through this evening. KTEB TAF Comments: Gusts may begin 1-2 hours later than forecast. KHPN TAF Comments: Gusts may begin 1-2 hours later than forecast. KISP TAF Comments: Gusts may begin 1-2 hours later than forecast. .OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... .Friday afternoon...Flurries or snow showers possible NW of the city. NW gusts 20-30 kt. .Saturday...VFR. .Sunday...Mainly VFR with a chance of light snow late. .Sunday night and Monday...MVFR or IFR in snow Sunday night changing to mixed precipitation near the coast on Monday. .Tuesday...Mainly VFR.
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&& .MARINE... Sub-SCA conditions are expected on the area waters this morning. This afternoon...the pressure gradient tightens and remains tight over all the waters through Friday. As a result expect gusts to 25-30 kt over the area waters. The gusts should start a few hours earlier on the ocean waters than the non-ocean waters, however for simplicity, have started the SCA everywhere at 18Z today. Gusts to 35 kt are possible on the ocean tonight and possibly Friday, however will hold off on any gale warning, thinking that these gusts would be more occasional than frequent. Gusty W-NW flow Friday night will diminish as the center of high pressure builds. Sub SCA conditions are anticipated through the weekend as the high settles to the south and a frontal boundary approaches from the west. Low pressure and the associated front approach and impact the waters Monday. SCA conditions are possible Monday, particularly across the ocean waters. Wave/sea forecasts are based on latest NWPS, with WaveWatch followed toward the end of the forecast. Seas subside as the winds diminish Friday night and through the weekend. && .HYDROLOGY... A widespread 1/2 inch or more of liquid equivalent precipitation is possible from Sunday night through Monday. && .EQUIPMENT...
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The New York City NOAA Weather Radio (NWR) transmitter, KWO35, is off the air. Time for a return to service is unknown. Central Park (NYC) observations (METAR) are currently unavailable. Technicians are troubleshooting.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 AM EST Saturday for ANZ330-335- 338-340-345-350-353-355. && $$ SYNOPSIS...BC/PW NEAR TERM... SHORT TERM...BC LONG TERM...PW AVIATION...CB/JMC/DS MARINE...BC/Goodman/PW HYDROLOGY...BC/PW EQUIPMENT...

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