Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 170017 AFDOKX Area Forecast Discussion National Weather Service New York NY 717 PM EST Tue Jan 16 2018 .SYNOPSIS... Low pressure develops along the Mid Atlantic coast tonight and then passes near or just east of Long Island on Wednesday before moving up the coast into the Canadian Maritimes Wednesday night. High pressure will then build to the south through Friday and move into the western Atlantic this weekend. A cold front then passes through Monday night into Tuesday morning. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Light snow continues across NW portions of Orange County. Radar returns are very light and accumulations have been slow through the day with a report in Greenville just under an inch. The steadier precipitation develops after midnight across the region. The forecast largely remains on track. The latest 18z models as well as the latest HRRR and HRRRx support the ongoing forecast for tonight into Wednesday morning so no major changes have been made. The biggest challenge continues to lie with the northward extent of the warmer air and how far the rain/snow line works. Right now, it appears that it should remain all snow just north of HPN and DXR, and about 10 to 20 miles to the north and west of the I-95 corridor in New Jersey. A prolonged period of SE winds in the low levels ahead of the developing low off the Mid Atlantic coat tonight will gradually increase temperatures in the boundary layer. This warming appears to be sufficient enough for primarily a rain event along the immediate coast. At the same time, interior sections of the Lower Hudson Valley and southwest Connecticut will be the recipients of a moderate snowfall event with amounts around warning criteria. No changes made to the winter weather headlines from the previous update. An amplifying upper trough moving across the Ohio valley tonight will allow for the forcing to shift to the Mid Atlantic coast tonight, with low pressure developing and tracking northeast to near or just southeast of Long Island in the morning. The transition of energy is slow enough that an inverted trough to the NW of the low track, extending back into the Hudson Valley of New York, will allow for an influx of warmer air ahead of the low. Temperatures will remain nearly steady overnight and even slowly rise. Lows will range from the upper 20s in the interior to the mid 30s along the coast. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Low pressure near Long Island in the morning lifts northeast during the day and up into the Canadian Maritimes by Wednesday night. Precipitation shuts down across most of the area by late morning/early afternoon and perhaps ends as period of snow at the coast. Even if the changeover to snow occurs a bit faster than indicated in the city/at the coast, limited duration of precipitation on the backside of the low will limit any accumulation. Highs will top out in the mid to upper 30s with NW winds developing on the backside of the storm. Gust up to 20 mph develop late in the day and possibly linger into first half of the night. Cold air will follow for Wednesday night with lows in the teens inland and around 20 at the coast. This is slightly below normal. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Surface high pressure will build to our south on Thursday and Friday. Meanwhile, an upper trough shifts through with some shortwave energy Thursday night into Friday. Moisture looks insufficient for any PCPN, so dry weather is expected. Highs a few degrees below normal for Thursday, returning to near normal on Friday. Ridging aloft will then keep the weekend dry with warming temperatures. Low pressure enters the Great Lakes Region Sunday night, eventually tracking through Quebec on Tuesday. Some warm advection PCPN may reach some of the northern zones Sunday night into Monday morning, which could be in the form of a wintry mix. A cold front otherwise approaches with increasing chances of rain during the afternoon and night. Some timing differences still exist among the global models with the cold front passage, so have capped PoPs at chance through Tuesday morning. Rain chances otherwise diminish Tuesday afternoon with dry weather likely returning Tuesday night. Temperatures Sunday through Tuesday will remain above normal. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... A developing coastal low with move north towards the region overnight, tracking just southeast of Long Island on Wednesday, and then into the Canadian Maritimes by Wednesday evening. Conditions expected to gradually lower to MVFR this evening, then lower to IFR late tonight as precipitation develops across region. Expect all snow at KSWF, which may be moderate at times between 06z and 12z. Rain expected to develop for NYC/NJ terminals after midnight, likely mixing with snow towards daybreak, and then briefly changing to all snow Wed morning. KHPN/KBDR may see a mix of rain/snow overnight, before changing to all snow towards daybreak. All rain expected to for KISP/KGON. Precip taper off from W to E Wed morning into early afternoon, with conditions improving to VFR. E/NE winds less than 10 kt overnight, becoming N/NNW towards daybreak. Winds become WNW with gusts 20 to 25 kt Wed afternoon continuing into eve push, likely averaging just right of 310 magnetic. NY Metro Enhanced Aviation Weather Support... Detailed information...including hourly TAF wind component fcsts can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: IFR conds expected with -RA/-SN mix or -SN for morning push. Snow totals less than 1 inch possible through Wednesday morning. Winds likely backing from NNE to NW during the morning push. VFR with NW gusts 20-25 kt for evening push. KLGA TAF Comments: IFR conds expected with -RA/-SN mix or -SN for morning push. Snow totals less than 1 inch possible through Wednesday morning. Winds likely backing from NNE to NW during the morning push. VFR with NW gusts 20-25 kt for evening push. KEWR TAF Comments: IFR conds expected with -SN for morning push. Snow totals of 1-2 inches possible through Wednesday morning. Winds likely backing from N to NW during the morning push. VFR with NW gusts 20-25 kt for evening push. KTEB TAF Comments: IFR conds expected with -SN for morning push. Snow totals of 1-3 inches possible through Wednesday morning. Winds likely backing from N to NW during the morning push. VFR with NW gusts to 20 kt for evening push. KHPN TAF Comments: LIFR conds expected with -SN for morning push. Snow totals of 2-4 inches possible through Wednesday morning. Winds likely backing from N to NW during the morning push. VFR with NW gusts to 20 kt for evening push. KISP TAF Comments: IFR conds with -RA expected for morning push. Winds likely backing from NE to N during the morning push. VFR with NW gusts to 20 kt for evening push. .OUTLOOK FOR 00Z THURSDAY THROUGH SUNDAY... .Wednesday night-Thursday...VFR. WNW winds G20-25KT for Wed Eve push and on Thursday. .Thursday night-Friday...VFR. W-SW winds G20KT possible. .Saturday-Sunday...VFR. && .MARINE... SCA in effect for the ocean waters as seas remain 4-5 ft. Ocean seas increase a bit more tonight. Flow returns to a NW direction and begins to gust late on Wednesday. SCA conditions continue on the ocean for Thursday through Friday morning, then sub-advisory conditions are expected for a brief period Friday afternoon and night. Winds and seas then pick up with marginal advisory conditions on the ocean during Saturday and Saturday night. A weaker pressure gradient then returns relatively tranquil conditions for Sunday. && .HYDROLOGY... No significant hydrologic impacts are expected. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...Winter Weather Advisory from midnight tonight to 1 PM EST Wednesday for CTZ005>008. NY...Winter Weather Advisory until noon EST Wednesday for NYZ069- 070. Winter Storm Warning until noon EST Wednesday for NYZ067-068. NJ...Winter Weather Advisory until noon EST Wednesday for NJZ002- 004-103>105-107. MARINE...Small Craft Advisory from midnight tonight to 6 AM EST Thursday for ANZ355. Small Craft Advisory until 6 AM EST Thursday for ANZ350-353. && $$ SYNOPSIS...JC/DW NEAR TERM...DW/DS SHORT TERM...DW/DS LONG TERM...JC AVIATION...NV MARINE...JC/DW HYDROLOGY...JC/DW EQUIPMENT...

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