Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 192054 AFDOKX Area Forecast Discussion National Weather Service New York NY 354 PM EST Sun Nov 19 2017 .SYNOPSIS...
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High pressure builds southwest of the region tonight, moving to the south of the region and eventually offshore Monday into Monday night. High pressure departs to the east Tuesday, followed by a cold front Wednesday. Another high builds late week before next system impacts the area next weekend.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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The polar upper level jet will be south of the region. In the mid levels, a trough axis moves through the region bringing its associated vorticity maxima with it. This upper level disturbance will enhance lift and with the leftover moisture, could result in a few snow showers with the continued cold air advection. Snow showers are the precip type due to wet bulb cooling. With limits in low level moisture and not much QPF from numerical model guidance, left as slight chance. At the surface, high pressure will build to the southwest of the region. The parent low attached to the cold front that moved across earlier will continue to deepen as it heads into Eastern Quebec. This will keep a steep pressure gradient within the region. Concerning winds, they will remain gusty out of the west but will be lowering in magnitude as the boundary layer winds are expected to lower. The decrease of temperature at the surface especially with the periods where there are fewer clouds will allow for surface to lower in temperature more, disrupting the vertical mixing and allowing for gusts to become infrequent. Wind advisory was not extended into the evening as winds in the 3-8kft layer show remarkable decrease more towards 30-35 kt going through the evening, making for less wind to mix down. This was conveyed with both NAM and GFS Bufkit soundings. Lows were a blend of MAV/ECS as MET numbers seemed too high.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
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The region is more in between the polar and subtropical upper level jets. In the mid levels, more of a ridging trend will take shape. At the surface, high pressure moves eastward towards the Carolina coastline Monday and then off into the Atlantic Monday night. Dry conditions are expected through the period. Monday is expected to be cooler, about 5 degrees below normal with more gusty WNW flow, mitigating sensible heat transfer. For Monday night, winds are expected to lower with gusts diminishing. With mostly clear conditions, expect radiational cooling to result in a more typical vast range of lows between the urban heat island and inland rural sections.
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&& .LONG TERM /TUESDAY THROUGH SUNDAY/...
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Better model agreement today in this active and progressive pattern. Aloft, active northern stream expected as multiple shortwaves pass during this time frame. Looks like the operational GFS has now trended much closer to other global models with handling of mid week trough. Latest GFS is notably weaker with trough along the Gulf states Wednesday, and is thus not developing a wave of low pressure off the coast Thursday, like it did 24 hours ago. As such, looks like WAA on the backside of the high will provide a mild/breezy day Tuesday, likely the warmest of this time frame. Plenty of sun will give way to increasing clouds as high level moisture approaches, along with moisture advecting from the south in the lower and mid levels. Nam/wrf seems to be the most aggressive in outputting precip ahead of the cold front. Still looks like best chance for rain will be east of NYC late Tuesday into Wednesday. Dry thereafter as ridge builds. A cold front passes with little fanfare Friday, then next shortwave approaches this weekend. Colder air advects in behind a front by Sunday. Minimal pops warranted next weekend with this system. Above normal temps Tuesday in WAA regime, then temps tumble to just below normal from late Wednesday through Sunday. Looks like a cool day Thursday, with a slight rebound Friday and Saturday before falling back again Sunday. A model/mos blend followed which is in line with latest WPC numbers.
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&& .AVIATION /21Z SUNDAY THROUGH FRIDAY/...
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High pressure builds in through tonight. VFR. WNW sustained winds 20-25 KT with frequent gusts around 30 KT and occasional gusts around 35 KT through 23z. Winds then back slightly by about 10-20 degrees this evening with sustained winds around 15 KT along with gusts 20-25 KT. .OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY... .Monday...VFR. W-NW winds G20-25KT. Gusts diminish gradually at night. .Tuesday...Mainly VFR. MVFR possible late Tuesday night in showers. SW winds G20-25KT. .Wednesday...MVFR possible with showers during the day. VFR at night. NW winds G20KT in the aftn/evening. .Thursday-Friday...VFR.
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&& .MARINE...
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Steep pressure gradient remains tonight, so still expecting gales for all waters tonight. Winds will be getting closer to 35kt through the night as boundary layer flow decreases. The boundary layer flow further decreases Monday with gales becoming marginal. SCA will then be more likely across the waters on Monday especially the ocean with high seas of 5-8 feet continuing. SCA conditions still probable for the ocean Monday night while non-ocean waters will see an eventual decrease in wind gusts to below SCA late. Winds increase in SW flow Tuesday. A few locations could approach gale force or 35 kt. Winds then diminish somewhat Tuesday night ahead of a cold front. Low pressure passes southeast of the waters Wednesday as the cold front crosses the area. NW flow Wed night back to the west and diminishes further Thursday as a ridge of high pressure builds. A cold front passes Friday, with the ridge building back yet again.
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&& .HYDROLOGY... No hydrologic problems are anticipated. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...Wind Advisory until 6 PM EST this evening for CTZ005>012. NY...Wind Advisory until 6 PM EST this evening for NYZ067>075- 078>081-176>179. NJ...Wind Advisory until 6 PM EST this evening for NJZ002-004-006- 103>108. MARINE...Gale Warning until 6 AM EST Monday for ANZ330-335-338-340-345- 350-353-355. && $$ SYNOPSIS...JM/PW NEAR TERM...JM SHORT TERM...JM LONG TERM...PW AVIATION...JC MARINE...JM/PW HYDROLOGY...JM/PW

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