Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 150304 AFDOKX Area Forecast Discussion National Weather Service New York NY 1104 PM EDT Sat Oct 14 2017 .SYNOPSIS... Weak high pressure builds into the region tonight and remains overnight, then drifts east during Sunday. A cold front approaches on Sunday and passes through the area late Sunday night. High pressure will build over the region for the rest of the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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A dense fog advisory has been issued through 6 am for portions of southern Connecticut and the twin forks of Long Island. If locally dense conditions continue to develop farther westward, the advisory may need to be expanded to western Suffolk County. Weak low level warm advection will be setting up after 03Z. So, temperatures and dew points are expected to remain nearly steady from current levels. However, temperatures may begin to rise, especially along the coast, late tonight. Vis in the fog was lowered in the grids to a half a mile across ern CT and LI. A broad upper ridge over the Southeast and Mid Atlantic states begins to give way to an approaching upper trough over the Midwest. This will result in a strengthening, deep-layered SW flow aloft and unseasonably warm and humid conditions for the remainder of the weekend. At the surface, the wave of low pressure that brought rain to eastern portions of the tri-state area on Saturday will pass well east of New England. In its wake, weak high pressure will build across the area tonight. The combination of moist low- levels and light winds will result in low clouds and areas of fog forming during the overnight hours. There is some uncertainty on how dense the fog gets and this may depend on how much clearing the area sees into early this evening. A dense fog advisory may be needed later tonight. Additionally, with the strengthening low-level southerly above the surface, drizzle will be possible as well.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... After some morning fog/drizzle, skies clear out with mostly sunny skies by afternoon. Sunday will be well above normal with temperatures generally in the mid to upper 70s. Gusty S-SW winds may get up to 30 mph in the afternoon. An upper trough and cold front will impact the area Sunday night with increasing clouds and a chance of showers. The best chance may actually be across eastern areas due to the availability of deeper moisture. Instability though is weak, so no thunderstorms are forecast. Rainfall amounts also look to be light with a lack of deep forcing. The cold front passes east of the area by daybreak Monday with strong cold advection and gusty NW winds. && .LONG TERM /MONDAY THROUGH SATURDAY/... A sprawling area of high pres will build from the w on Mon, then set up over the area thru Sat. A residual shwr is possible Mon mrng, otherwise it will be a breezy day with mixing likely abv h85. This will allow for temps to peak in the 60s. For Mon ngt, it appears the winds will stay up, especially along the coasts, limiting temp drops. A blend of guidance was used. If winds decouple, fcst temps will need to be lowered and there could be some patchy frost in the normally colder outlying spots. The high builds in for the rest of the week keeping the area dry and mostly clear. A blend of the guidance was used for temps, with readings quickly shooting abv average from midweek on. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... A weak surface pressure gradient will be across the region through late tonight as high pressure over the northern Atlantic moves well off shore and low pressure moves into the Great Lakes. The low moves into southeastern Canada Sunday as a cold front approaches. Forecast timing of lowering ceilings and visibilities through the overnight difficult. Initially, conditions will be variable from MVFR to VFR for ceilings with local areas IFR at times. Conditions are expected to lower with widespread IFR developing in fog, stratus, and areas of drizzle, late in the evening and overnight, especially across the coastal areas. Areas of LIFR and likely with even VLIFR in visibilities at times. Conditions improve slowly after sunrise Sunday, eventually becoming VFR, with the exception of KGON where VFR is not expected until mid afternoon. Winds will be light and variable to calm, with a light southerly flow developing along the south coast of Long Island late tonight. S to SW winds increase Sunday to 10 to 15 KT with gusts developing early in the afternoon, gusting 18-25 KT. .OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY... .Sunday Night...VFR early, then a chance of showers after 03Z with MVFR conditions. SW winds G20-25KT early in the evening. Winds shift to NW after 08Z and gust 20-25KT. .Monday...Chc early AM showers and MVFR/IFR, becoming VFR. NW winds G20-25KT. .Tuesday-Thursday...VFR. && .MARINE... Fog has developed and become dense across the eastern forecast waters. Issued a dense fog advisory through the overnight. Marginal SCA seas will continue on the ocean waters tonight due to a SE swell. SCA winds and seas expected to build on the ocean in a strengthening SW flow ahead of an approaching cold front Sunday aft/eve, and then likely with the NW flow in its wake late Sun Night into Mon morning. SCA gusts are likely on all waters, pre and post frontal. Winds and seas will remain at sca lvls Mon, then subside Mon ngt. Winds and seas will then remain blw sca lvls for the rest of the week. && .HYDROLOGY... No hydrologic issues expected through the end of next week. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Dense Fog Advisory until 6 AM EDT Sunday for CTZ006>008- 010>012. NY...Dense Fog Advisory until 6 AM EDT Sunday for NYZ079-081. NJ...None. MARINE...Small Craft Advisory from noon Sunday to 6 AM EDT Monday for ANZ330-335-338-340-345. Dense Fog Advisory until 6 AM EDT Sunday for ANZ330-340-345- 350-353. Small Craft Advisory until 6 PM EDT Monday for ANZ350-353-355.
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&& $$ SYNOPSIS...JMC/DW NEAR TERM...JMC/MD/DW SHORT TERM...DW LONG TERM...JMC AVIATION... MARINE...JMC/DW HYDROLOGY...JMC/DW is the U.S. government's official web portal to all federal, state and local government web resources and services.