Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 222311 AFDOKX Area Forecast Discussion National Weather Service New York NY 711 PM EDT Tue Aug 22 2017 .SYNOPSIS... A cold front approaches tonight and passes through Wednesday morning. High pressure then dominates the weather pattern from Wednesday afternoon into early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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Forecast is on track with some minor changes made to reflect current conditions. Earlier this afternoon, 2 lines of convection were moving toward the area, with some of the thunderstorms becoming severe. A fair amount of weakening has occurred with these lines over the last couple of hours and much of the dynamics to support severe thunderstorms have pushed well north of the tri- state. Also, the 2 lines have become one larger area of showers and thunderstorms, with a more stratiform look to it over central Pennsylvania. Cloud top warming is also noted in the IR. With that said, there still is a chance for some of the storms that form ahead of this main area to become strong to severe, with the main threat being damaging winds in the strongest storms. A Severe Thunderstorm Watch has been issued for Passaic, Orange, and Putnam counties until midnight tonight. A pre-frontal trough and cold front move in from the west. Showers and thunderstorms are expected with both boundaries. CAPE and shear values are sufficient for strong storms with gusty winds. Some of these storms may become severe, with damaging winds being the main threat across Passaic, Orange, and Putnam counties and a Severe Thunderstorm Watch has been issued until midnight tonight for these areas. Better chances for the stronger gusts would be along the pre- frontal trough as CAPE will be greater during the evening hours. The trailing cold front will have less CAPE to work with during the overnight hours, but winds aloft may still allow for strong gusts. The steering flow should be quick enough to mitigate chances of flash flooding and training of cells is not expected to be a factor, but with high moisture content around, minor nuisance/urbanized flooding is possible. A high rip current risk remains in effect into tonight.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... The cold front will be right over the tri state area at the start of Wednesday morning and should be east of Montauk by late morning. Still cannot rule out a lingering shower or thunderstorm mainly east of the city in the morning. Much drier air then filters in behind the cold front for the afternoon with mostly sunny conditions. It will start to feel less muggy as well, and highs will be in the lower and mid 80s. Mainly clear for Wednesday night. Low temperatures across the northernmost suburbs and the Pine Barrens Region are expected to drop into the mid 50s. There is a moderate rip current risk for Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... A mainly quiet weather pattern takes shape in the long term as canadian high pressure will dominate with below normal temperatures and mainly dry conditions. Anomalous longwave trough will be swinging across the eastern states on Thursday, with a vigorous piece of energy trailing behind the main trough axis. This energy is progged to dive towards the region Thursday night into early Friday morning at the same time of some upper jet support. While ensemble members and deterministic runs are dry with this feature, there is enough lift and brief moisture return to warrant a low chance pop for showers. The shortwave energy shifts offshore Friday morning, with the main upper trough lingering just to the east through the weekend with tranquil conditions. The surface high settles over the northeast for the weekend, then centers itself off the New England coast early next week as ridging builds aloft. 850 temperature anomalies will run 3-6C below normal into the weekend. This will result in surface temperatures running several degrees below normal. Forecast highs may be warmest on Thursday, in the upper 70s and low 80s, and then run in the middle and upper 70s through Sunday. A more easterly flow sets up early next week which should help keep highs below normal. Nighttime temperatures will range from the lower 50s inland to the lower 60s near the coast. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... A cold front approaches the region late today and crosses tonight. South/Southwest winds will remain gusty into the evening push. Gusts of 20 to 25 knots expected, with occasional higher gusts possible along the coastal terminals. A line of showers/thunderstorms will track across Central NY/PA this evening. Majority of hi-res guidance, including last several runs of HRRR, is indicating weakening, with stronger looking storms passing to the N, as they approach NYC/NJ terminals between 04z and 07z. Due to this, have not included a tempo in the 21z TAF amendments as confidence is not high enough for it or a prevailing VCTS and prob30 can no longer be used. Not completely ruled out, still a 20-30% chance at the metro terminals. Confidence slightly higher to the N, thus have maintained mention at KSWF/KHPN. Gusty winds and MVFR possible in any stronger thunderstorm. This activity slowly moves through the area overnight. MVFR to IFR conds may redevelop/persist especially at KBDR/KISP/KGON until cold fropa passes. Northwest flow may be just strong enough to preclude seabreeze development Wed aftn. Otherwise...VFR. ...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: 20-30% chc tstms 04z-07z. Seabreeze possible, but more unlikely to occur Wed aftn. KLGA TAF Comments: 20-30% chc tstms 04z-07z. KEWR TAF Comments: 20-30% chc tstms 04z-07z. KTEB TAF Comments: 20-30% chc tstms 04z-07z. KHPN TAF Comments: 30-40% chc tstms 04z-07z. KISP TAF Comments: MVFR to IFR possibly redeveloping this eve and persisting until late tonight. .OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY... .Wednesday...Low prob of -shra/MVFR AM...mainly eastern terminals. Becoming VFR in AM. W-NW G15KT possible. .Wednesday night-Sunday...VFR. && .MARINE... SCA remains on all waters for tonight. Extended the SCA on the ocean waters until late morning/early afternoon Wednesday as seas at 5 ft probably linger at least into Wednesday morning. Sub-SCA conditions then for all waters by late Wednesday afternoon, lasting into the night. Tranquil conditions and sub-SCA winds and seas are forecast on the waters Thursday through the weekend as high pressure will be in control. && .HYDROLOGY... Showers and thunderstorms through tonight may cause minor nuisance/urbanized flooding. No widespread hydrologic impacts are forecast through the rest of the week. && .TIDES/COASTAL FLOODING... Tides are running high astronomically. Water levels will approach minor flood levels across mainly the south shore bays areas with tonight`s high tide, but are likely to remain just below. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...High Rip Current Risk until 9 PM EDT this evening for NYZ075- 080-081-178-179. NJ...None. MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ330-335- 338-340-345. Small Craft Advisory until 11 AM EDT Wednesday for ANZ353-355. Small Craft Advisory until 2 PM EDT Wednesday for ANZ350.
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&& $$ SYNOPSIS...JC/DS NEAR TERM...JC SHORT TERM...JC LONG TERM...DS AVIATION... MARINE...JC/DS HYDROLOGY...JC/DS TIDES/COASTAL FLOODING...

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