Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 240206 AFDOKX Area Forecast Discussion National Weather Service New York NY 1006 PM EDT Sun Oct 23 2016 .SYNOPSIS... Fast moving low pressure and an associated cold front will move through overnight. High pressure will build across from Monday into Wednesday night. A frontal system will approach from the west on Thursday and move across Thursday night into early Friday, followed by weak high pressure later Friday into Saturday. A series of weak frontal systems will then approach Saturday night into Sunday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Winds continue to diminish late this evening as the pressure gradient relaxes with the approach of weak low pressure from the lower Great Lakes. Upstream radar shows bands of showers and even a few tstms extending across Lake Erie into western PA in association with the low. This activity moves quickly ESE, impacting mainly the lower Hudson valley after midnight and then southern CT/eastern Long Island after midnight, with likely PoP there, and chance PoP for NYC metro. Convective indices showing total totals and Showalter indices near 50 and 0 respectively, also MUCAPE increasing to near 500 J/kg over eastern Long Island and the coastal waters late tonight, indicate some potential for thunder. In fact SPC has placed the area under a marginal threat for thunderstorms for the overnight period. Temperatures have cooled, but may hold steady or even rise a degree or two as the night progresses due to clouds and SW winds ahead of the low. These trends will be tough to pin point. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... The front and low should be off shore by 12Z. Cold advection sets up and continues through Monday, and gusty northwest winds develop. Low level winds will not be as high as Saturday and Sunday and peak gusts will be in the 25 to 30 KT range. A deep northwest flow will continue across the region Monday night as the upper trough remains over eastern Canada. Inland winds will decouple Monday night and with clear skies temperatures are expected to fall into the mid and upper 30s. There still will be enough of a wind and drying will occur, so do not expect a widespread frost. && .LONG TERM /TUESDAY THROUGH SUNDAY/... An upper trough will remain over the Northeastern states and eastern Canada through Wednesday. A gusty NW flow will prevail, and with cyclonic low level flow expect more in the way of clouds on Tue, especially across the interior where downslope effects will not dry out the column as much. As the high builds across on Wed, it should be quite cool, with high temps only from the mid 40s to lower 50s. Strong radiational cooling under the high Wed night could lead to a hard freeze across much of the interior especially NW of NYC, with lows ranging from the mid 20s to lower 30s, and falling even to the mid 30s in NYC. A passing frontal system will bring the next chance of rain from Thursday afternoon into early Friday morning, with the bulk of the rain falling Thursday night. Bumped PoP up to likely for Thu night as a result. If the system moves through as quickly as latest guidance suggest, Friday could be dry throughout, but held onto a morning chance for eastern Long Island and SE CT. Forecast certainty diminishes after Friday, with big timing differences noted with a series of frontal systems moving through. Have only a broad-brush slight chance PoP from Sat night into Sunday, and this could change as the more likely time periods for rain come into focus in later forecast cycles. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... A fast moving cold front moves through overnight into early morning. Mainly VFR overnight, with a low chance for brief MVFR ceilings in showers after midnight, until 6 am. Best chance for showers will remain across interior airports, and southern CT airports. Cannot rule out thunder, but should be isolated and is not included in the forecast. VFR Monday with scattered to perhaps broken stratocu. Winds will back to the SW overnight, generally around 5-10 kt. After the cold front passage early Monday, winds will shift to the NW and increase with gusts 20-25 kt by late morning. Expect sustained winds of 15 to 20 kt with gusts in the 20 to 30 kt range during the afternoon. .Outlook for 00Z Tuesday through Friday... .Monday night...VFR with NW winds. Occasional gusts possible. .Tuesday...VFR. NW winds G25-30 kt, diminishing Tuesday night. .Wednesday...VFR. NW-NNW G20 kt possible near the coast. .Thursday-Friday...MVFR or lower possible late Thursday into early Friday in rain. && .MARINE... For the non ocean waters, winds should remain below 25 Kts overnight as the pressure gradient relaxes ahead of low pressure. For the ocean waters, winds should diminish somewhat, but will remains gusty, and seas remain 5 ft or higher. SCA conditions should redevelop on all waters from Monday into Tue evening as a strong/gusty NW flow develops behind the cold front. As such, a new SCA has been posted through Monday night for now. These conditions should continue on the ocean and the eastern Sound late Tue night, and possibly into Wed morning. SW flow increasing to 15-20 kt Thu night ahead of a frontal system could push ocean seas up to 5 ft Thu night. Post-frontal WNW flow could gust up to 25 kt on the ocean on Fri as well. && .HYDROLOGY... QPF from 1/10 to 1/4 inch likely overnight, with the higher amounts inland and across eastern Long Island. Most likely QPF with a passing frontal system Thu afternoon into early Fri morning ranges from 1/2 to 3/4 inch. Local amounts over an inch are possible. No hydrologic impacts expected attm. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from 6 AM Monday to 6 AM EDT Tuesday for ANZ330-335-338-340-345. Small Craft Advisory until 6 AM EDT Tuesday for ANZ350-353-355. && $$ SYNOPSIS...Goodman/MET NEAR TERM...Goodman/MET/PW SHORT TERM...MET LONG TERM...Goodman AVIATION...PW MARINE...Goodman/MET/PW HYDROLOGY...Goodman/MET/PW is the U.S. government's official web portal to all federal, state and local government web resources and services.