Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 242046 AFDOKX Area Forecast Discussion National Weather Service New York NY 346 PM EST Fri Nov 24 2017 .SYNOPSIS...
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High pressure off the mid Atlantic coast weakens tonight into Saturday. A cold front approaches Saturday and moves through Saturday evening. High pressure builds in Sunday through Tuesday. Another cold front will move across on Wednesday. High pressure builds briefly Wednesday night then lifts north of the area as the next storm system approaches on Friday.
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&& .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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Upper zonal flow gradually becomes southwesterly tonight as a ridge moves into the western Atlantic and a northern stream trough digs into the upper midwest. Meanwhile a southern stream shortwave will be pickup by the trough and moved into the western Atlantic. This will spin up a weak surface low that moves to off the North Carolina coast by 12Z Saturday. The atmosphere will remain dry, and surface wind will be light with good radiational cooling tonight. This will lead to a wide range of overnight lows. There will be weak warm advection from around 950 to 850 MB, but with little moisture or lift, clouds are not expected.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
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Late in the day Saturday a cold front will be approaching as the associated low moves into eastern Canada. The northern stream trough moves to the east coast by Saturday night with weak lift. There may be a few showers bu late in the day into the far western zones. Lift will increase Saturday night as a rather strong vort max rotates into the based of the upper trough and then, with progressive flow, quickly moves into the western Atlantic. Again moisture will be limited. So will keep probabilities in the slight chance to chance categories. Cold air will be lagging behind before the precipitation ends so expect all liquid, light, precipitation. And with the quick flow precipitation will end before 11Z Sunday.
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&& .LONG TERM /SUNDAY THROUGH FRIDAY/...
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High pressure will build in from Sunday through Tuesday with a warming trend into Tuesday, near seasonal normals. A frontal system is then expected to move across the area on Tuesday night. Moisture associated with the frontal passage is expected to dissipate as it approaches the area. Kept the local area precipitation free during this period. Temperatures on Wednesday will continue to be above normal with high in the low to mid 50s. High pressure builds briefly on Wednesday night and into Thursday before moving north of the area. Another storm system is forecast to move across the area on Friday. Temperatures on Thursday and Friday will be near normal for this time of year.
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&& .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
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High pressure will gradually give way to an approaching cold front over the Great Lakes, which passes through region Saturday evening. S-SW winds generally 10kt or less, occasional gusts to the mid teens possible for south coastal terminals tonight into Saturday. 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: Winds may vary 20 degrees around 180 early this evening. KLGA TAF Comments: Winds may vary 20 degrees around 180 early this evening. KEWR TAF Comments: Winds may vary 20 degrees around 180 early this evening. KTEB TAF Comments: Winds may vary 20 degrees around 180 early this evening. KHPN TAF Comments: No unscheduled amendments expected. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY... .Saturday Afternoon/Night...Low chance of -SHRA and MVFR with frontal passage in the evening. SW gusts 15 to 20 kt. Windshift from SW to NW in the evening. NW Gusts 20-30KT late night, with an isolated rain/snow shower possible. .Sunday...VFR. NW winds G20-30kt. .Sunday Night-Monday...VFR. W winds G15-25kt. .Tuesday...VFR. SW winds G15-25kt. .Tuesday Night-Wednesday...VFR.
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&& .MARINE...
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As high pressure south of the ocean forecast waters weakens tonight and one low moves off the southeast coast as another moves through southern Canada, the pressure gradient force will increase through tonight. This will allow for southwest wind to increase. However, winds and gusts are expected to remain below small craft levels tonight through Saturday. Capped the ocean waves at 4 feet as NWPS was running around 1 foot too high compared to current conditions. And with southwest flow tends to be too high, so again capped waves at 4 feet into Saturday night. There is a chance that late Saturday night waves do build to 5 feet briefly in northwest gusts winds behind a cold front. Expected ocean gusts to be marginally around small craft levels in the cold advection behind the front late Saturday night. So, will begin an advisory at 06Z Sunday. SCA conditions forecast on Sunday as a northwest flow increases across all ocean waters to 25 to 30 kt. SCA conditions could continue on the ocean into Sunday night and maybe into Monday morning, then fall below SCA conditions later on Monday and into Tuesday. Seas might rise to SCA conditions again Tuesday night and into Wednesday ahead of the next frontal system.
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&& .HYDROLOGY... No hydrologic impacts expected. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from 1 AM to 6 PM EST Sunday for ANZ350- 353-355.
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&& $$ SYNOPSIS...Fig/19 NEAR TERM...19 SHORT TERM...19 LONG TERM...Fig AVIATION...DW MARINE...Fig/19 HYDROLOGY...Fig/19

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