Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 231542 AFDOKX Area Forecast Discussion National Weather Service New York NY 1042 AM EST Tue Jan 23 2018 .SYNOPSIS...
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A warm front lifts north of much of the area by late this morning. A cold front then crosses the area this afternoon and early evening, followed by a trough of low pressure. High pressure builds through the mid to late week period. A cold front may impact the area later this weekend or early next week.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Axis of heaviest rain aligning itself with nose of low-level jet right along the NJ coast. This activity will work northeast across Long Island and Connecticut through early this afternoon with heavy rain showers and possibly isolated thunderstorms. Rainfall rates may approach half inch an hour with localized higher amounts. This may require the issuance of Flood Advisory for minor nuisance, poor drainage flooding. Warm front has pushed through coastal Connecticut and southern portions of the Lower Hudson Valley, as far north as White Plains. Its questionable how far north it gets across sections of the Lower Hudson Valley before the cold frontal passage early this afternoon. This may play havoc with temperatures across some of the valley locations where cooler air is trapped, though above freezing. Vigorous trough approaches, and it appears showers move quickly from west to east this morning, and pass to the east this afternoon, clearing eastern locations by late in the day. Will maintain thunder mention as some elevated instability has been noted in models and observed already. Gusty winds are possible in any heavier showers/thunderstorms. LLJ along the coast would result in a few strong gusts, but these strong gusts are not likely. Usual dilemma of breaking the strong inversion. Plenty of moisture has been tapped, seen on water vapor imagery, extending back to the Gulf of Mexico, and even the Pacific. Some showers will be heavy into this afternoon, but mainly east of NYC, NE NJ, and the Lower Hudson Valley. Rainfall amounts across eastern Long Island and SE CT may exceed an inch. Temperatures rise in southerly flow, once the warm front jumps northward. Widespread 50s are expected for highs, with a few 60 degree readings possible in NE NJ.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... Upper trough passes across New England tonight as the cold front over eastern New England continues to move well to the east. Sfc trough passes late tonight or early Wednesday, and next upper level shortwave approaches, passing later Wednesday or Wednesday night. Other than a few clouds, do not expect any precipitation as much drier air sweeps eastward. This is due to deepening low pressure over the Canadian Maritimes, and subsequent gusty W/NW flow due to a tight pressure gradient. CAA during this time frame will result in cooler temperatures, if not quite a return to seasonal normals. For nighttime lows, temps range from the upper 20s to the middle 30s as atmosphere remains mixed. On Wednesday, temperatures should reach the upper 30s to lower 40s per mos blend. Temperatures should be a little colder Wednesday night as high pressure approaches. Lows in the teens and 20s are expected at this time under partly cloudy skies. If radiational cooling does not take place due to persistent winds, then temps may not fall quite as low as forecast. && .LONG TERM /THURSDAY THROUGH MONDAY/... Ridge builds, and dry conditions continue through at least Saturday. Initial cold will moderate as the ridge builds and high pressure passes offshore. Model timing differences arise Sat night through Monday, with GFS a weak and progressive outlier with downstream trough. Best chance for showers looks to be late Sunday, Sunday night and possibly into Monday, but confidence in details remains rather low at this time. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/...
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Warm front has now pushed north of all terminals with the exception of KSWF. A strong cold front will move east across the area this afternoon into early evening. IFR conditions will continue at most terminals through the late morning hours and into the early afternoon in SHRA. Rain could be moderate to heavy at times, especially across the Long Island and Connecticut terminals, and an isolated thunderstorm can`t be ruled out. A period of improvement to MVFR is possible late this morning ahead of the cold front as initial SHRA move off to the east, primarily for the city terminals. Rain then ends from w to e with conds improving to MVFR then VFR late this afternoon into evening push for NYC/NJ metro terminals, possibly lingering into evening push for eastern terminals. Southerly flow will continue to increase, with gusts to 25-30 kt. The highest gusts are expected east of the city terminals, with 30 kt or higher gusts possible for KISP/KGON. Isolated higher gusts possible. LLWS/Compression continue into this afternoon with SSW winds of 50-60 kt as low as 1500ft. Cold frontal passage with wind shift to west will to occur late afternoon/early eve with gusts 25 to 30 kt possible. 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: IFR expected through mid afternoon. Low prob of sparse thunder through 20z. LLWS through 20z. Occasional S G30 kt possible until 20z. For evening push, VFR likely with W G25-30 kt possibly developing. The afternoon KJFK haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KLGA TAF Comments: IFR ceilings expected through mid afternoon. Low prob of sparse thunder through 20z. LLWS through 20z. Occasional S G30 kt possible until 20z. For evening push, VFR likely with W G25-30 kt possibly developing. The afternoon KLGA haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KEWR TAF Comments: Occasional IFR conditions through mid afternoon, otherwise MVFR. Low prob of sparse thunder through 20z. LLWS through 20z. Occasional S G25-30 kt possible until 20z. For evening push, VFR likely with W G25-30 kt possibly developing. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Occasional IFR conditions through mid afternoon, otherwise MVFR. Low prob of sparse thunder through 20z. LLWS through 20z. VFR likely for evening push. KHPN TAF Comments: IFR/LIFR expected through mid afternoon. Low prob of sparse thunder through 20z. LLWS through 20z. Occasional S G25-30 kt possible until 20z. Improvement to VFR likely during evening push. KISP TAF Comments: IFR expected through afternoon. Low prob of sparse thunder through 21z. LLWS through 21z. Occasional S G30-35 kt possible until 21z. Improvement to VFR likely during evening push. .OUTLOOK FOR 12Z WEDNESDAY THROUGH SATURDAY... .Wednesday...VFR. WNW G20-25KT. .Thursday-Friday...VFR. .Saturday...Showers possible with S-SW G20KT.
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&& .MARINE...
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Southerly flow will rapidly strengthen across the area waters this morning with SCA winds expected across all waters. A strong LLJ working across the water late this morning through afternoon will bring potential for occasional gale gusts for all waters, with gale conditions expected for central and eastern oceans waters where gusts to 35 kt are possible. Seas will rapidly build in response to the strengthened flow this morning, peaking at 8 to 12 late today. Winds may briefly drop off as the front moves through late today into early this evening, before strengthening again following its passage. SCA gusts in the 25 to 30 kt range are expected tonight into Wednesday on all waters. Winds should gradually fall below SCA late Wednesday into Wednesday night, with ocean seas following suit. Winds and seas will then creep up towards sca levels again on Thursday as low pressure deepens over the Atlantic. Winds and seas should be below SCA levels on Friday, then sw flow increases over the weekend ahead of a frontal system.
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&& .HYDROLOGY...
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Total rainfall through this afternoon is expected to range from around 1/2 to 1 1/2 inches, highest across eastern Long Island and southeast Connecticut. Localized ponding of water in poor drainage areas is expected, but no significant hydrologic issues are anticipated at this time. Best chance for any flooding would be confined to urban areas. Dry thereafter until later this weekend.
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&& .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 PM EST Wednesday for ANZ330-335- 338-340-345-355. Gale Warning until 6 AM EST Wednesday for ANZ350-353.
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&& $$ SYNOPSIS...PW/DW NEAR TERM...DW/PW SHORT TERM...PW LONG TERM...PW AVIATION...FEB/NV MARINE...NV HYDROLOGY...PW/DW EQUIPMENT...//

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