Area Forecast Discussion
Issued by NWS Upton, NY

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388 FXUS61 KOKX 300856 AFDOKX Area Forecast Discussion National Weather Service New York NY 456 AM EDT Fri Sep 30 2016 .SYNOPSIS... High pressure over southern Quebec will maintain a moist northeast flow off the Atlantic Ocean into the weekend as low pressure spins over the Ohio Valley. The unsettled weather may continue into early next week before high pressure begins to exert its influence from the north for mid week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Unsettled weather will continue through this evening as a cut off low meanders over the Mid-West while at the same time, a frontal boundary slowly moves north toward the area. Models continue to differ significantly with rainfall amounts. Given that much of what is on the radar as of 0830Z remains either west or east of the area, decided to lower QPF amounts quite a bit from previous forecast package. Only expecting about half an inch or slightly more through this afternoon for Long Island and the New York City metro area with lesser amounts for the Lower Hudson Valley and inland Southern Connecticut. It will be breezy today as a tight pressure gradient between the high pressure to our north over Southern Quebec and the low over the Mid-West continues. Winds could gust to 35-40 mph, mainly along the coast. With the blocking pattern in place, persistence will be the forecast. Continued cloudy today. Highs will be a few degrees lower than yesterday, with portions of the Lower Hudson Valley and inland Southern Connecticut not even reaching 60. Generally, upper 50s to lower 60s for high temperatures for the entire area.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
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Chances for rain continue into the short term with the cut off low remaining to the west and the frontal boundary to our south. Again, models differ on exact placement of the heaviest rain. Expecting anywhere from 3/4 to 1 1/3 inches of rain, with the heavies falling across Eastern Long Island, from Friday morning through the day Saturday. Winds diminish Friday night as the high pressure retreats farther north into Canada. Temperatures will be a bit warmer on Saturday, but still a bit below normal for this time of year, generally lower to middle 60s.
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&& .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
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No significant changes made to the long term period as a stagnant and unsettled weather pattern continues for the weekend and into early next week as a stacked cutoff low remains over the Ohio Valley as a ridge over the Western Atlantic remains in place. Models continue to show the upper ridge gradually weakening and shifting south enough early next week to allow the upper low to finally start moving northeast early next week. At the surface, stacked low pressure sits over the Ohio Valley, with a stationary front running northeast from the Mid Atlantic and southeast of Long Island through the weekend. A series of weak waves running along this front will produce periods of rain this weekend. Then as the stacked low finally begins to lift northeast early next week, expect the the main moisture/lift axis to also weaken and lift NE. Lingering scattered showers could continue through early next week via cold pool instability interacting with the maritime air mass. Thereafter, potential for deep layered ridging developing for mid week as the region lies under ridging of an omega blocked pattern. The dry ridged pattern may continue into late week, but will have to monitor the evolution of Hurricane Matthew. Please refer to the National Hurricane Center forecasts for further information. Temperatures will be at or slightly below normal on Sunday, then return to near seasonable for early next week.
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&& .AVIATION /09Z FRIDAY THROUGH TUESDAY/...
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Terminal area will be in between high pressure to the northeast and low pressure to the southwest today. MVFR this morning, bcmg IFR this aftn. Tempo IFR vsbys in rain possible this morning. NE-E winds gusting to 25-35 KT at city/coastal terminals and 20-25 KT at inland terminals. ...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: Gusts before 12z might be only occasional. Timing of IFR may be off by a couple of hours. KLGA TAF Comments: Timing of IFR may be off by a couple of hours. KEWR TAF Comments: Gusts before 12z might be only occasional. Timing of IFR may be off by a couple of hours. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Gusts before 12z-13z might be only occasional. Timing of IFR may be off by a couple of hours. KHPN TAF Comments: Gusts before 12z-13z might be only occasional. Timing of IFR may be off by a couple of hours. KISP TAF Comments: Gusts before 12z might be only occasional. Timing of IFR may be off by a couple of hours. .Outlook for 06Z Saturday through Tuesday... .Friday night-Saturday...IFR/MVFR in rain. NE gusts around 20 KT Friday night. .Saturday Night-Sunday Night...MVFR or lower possible with showers. .Monday-Tuesday...VFR with isolated to scattered showers possible.
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&& .MARINE...
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Gale winds are expected to continue today as the tight pressure gradient with the high over Southern Canada and low over the Mid- West continues. The Gale Warnings were extended into early tonight, but the winds should gradually diminish tonight as the high retreats farther north into Canada. Winds should come down below Gale Warning criteria after 8 pm tonight, with SCA winds expected through the remainder of the night. Seas on the ocean will range from 8-13 ft, while 5-7 ft are expected on the Sound. SCA criteria should continue into mid Saturday morning for the ocean waters, while everywhere else, winds will come down below 25 kt around sun rise. Waves over the Sound will also come down below 5 ft by around sun rise on Saturday. Waves will diminish on the ocean waters as well, but they will remain at or above 5 ft through the day Saturday. Conditions fall below SCA levels Sat night into early Sunday as easterly flow weakens and seas subside. These sub-SCA conditions will remain likely for early next week under a weak pressure gradient. Seas on the ocean waters start to increase mid week with small craft conditions returning.
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&& .HYDROLOGY...
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There is a high degree of uncertainty on the amount of rainfall through Saturday. 1-1 1/2 inches of QPF possible through Saturday night. The prolonged nature of the rain event should preclude any hydrologic issues. No significant rainfall for early to mid next week.
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&& .TIDES/COASTAL FLOODING...
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With slight strengthening of ENE gales this morning`s high tide cycle, would expect surge to at least match or even slightly exceed that of last night`s. With a slightly higher astronomical high tide, this should result in widespread minor coastal flooding for the above mentioned areas. Along western Long Island sound and the eastern bays of Long Island, wind fields will be slightly weaker the next 12 hours, and may be falling off by high tide times Fri late morning, but can`t rule out localized minor coastal flooding or wave splashover in the most vulnerable northeast and east facing spots during high tide. Although wind fields weaken for Fri evening high tide, widespread minor flooding continues to be a concern for the south shore of Long Island and thus a Coastal Flood Advisory was issued for this time frame for Southern Nassau County. Additionally, a persistent easterly sweep of 6 to 10 ft surf through Friday will likely result in minor to moderate beach erosion issues at the the ocean beachfront.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...Coastal Flood Advisory until 11 AM EDT this morning for NYZ074- 075-080-178-179. Coastal Flood Advisory from 6 PM to 10 PM EDT this evening for NYZ179. NJ...Coastal Flood Advisory until 11 AM EDT this morning for NJZ006- 106-108. MARINE...Small Craft Advisory until 8 AM EDT Saturday for ANZ338. Gale Warning until 8 PM EDT this evening for ANZ330-335-340- 345-350-353-355.
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&& $$ SYNOPSIS...BC/JP NEAR TERM...JP SHORT TERM...JP LONG TERM...BC AVIATION...JC MARINE...BC/JP HYDROLOGY...BC/JP TIDES/COASTAL FLOODING...

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