Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 191132 AFDOKX Area Forecast Discussion National Weather Service New York NY 732 AM EDT Sun Aug 19 2018 .SYNOPSIS... A cold front south of Long Island will continue to slowly sink into the Mid Atlantic region today as a wave of low pressure travels along it. A high pressure ridge will extend southwest from New England Monday into Tuesday while weak low pressure passes to the south. A cold front will move across on Wednesday, followed by high pressure to close the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Frontal boundary has pushed into southern NJ early this morning and will continue into the Mid Atlantic region this morning as a weak wave of low pres tracks along it. Meanwhile, an upper trough will track through the Northeast. Coverage of showers is slightly more than expected this morning, so have increased pops a bit. Hi res guidance remains split on whether this becomes more widespread later today and thus remains the most uncertain part of the forecast. While it makes sense that southern portions of the forecast area have a greater potential, think the widespread nature is overdone. A rumble of thunder cannot be ruled out this morning, but by aftn there really is minimal instability (including elevated instability) for tstm activity. Thus, it has not been included in the forecast. If there was any convection, heavy rain and potential flooding would be a concern with PW`s around 1.75 inches and a weak steering flow, but am not really seeing a potential for this. Moderate showers are possible, but do not anticipate flooding with these. Otherwise, a cloudy and much cooler day under a NE flow. Highs are forecast to be in the lower to mid 70s, but they may need to be knocked down 1-2 degrees. There is a moderate risk for the development of rip currents at the ocean beaches today. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... The upper trough will be slow to depart the northeast tonight and Monday due to downstream ridging. Thus have maintained low pops tonight through Mon morning. By Mon aftn, the trough should be far enough east with enough subsidence from a ridge of high pres extending through New England to keep conds dry. Waves of low pres will continue to pass to the south through Mon night, but are expected to be far enough south to not impact the local area. A frontal system will then approach the area on Tuesday with increasing chances for rain returning during the aftn. There is a moderate risk of rip current development on Monday. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... With the approach/passage of a more significant upper trough and associated cold front Tue night into Wed, will see likely PoP late Tue night and possibly into Wed morning. See Hydrology section for further details, as there could be some urban and flash flood potential, impacting the Wed AM rush if current model timing holds. With mid level confluence behind this departing trough on Thu and then ridging aloft Fri into Sat, sfc high pressure should then follow, with a noticeably drier air mass moving in on Thu with dewpoints in the 50s and remaining into Saturday. Except for Tue night/Wed when temps may be a few deg above avg, expect temps right near seasonal averages. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... A frontal boundary will remain south of the terminals. NE flow will continue across the area through the TAF period. MVFR cigs, generally between 1-2kft expected through much of the TAF period. There may be some slight improvement this afternoon, but still expecting CIGs to remain MVFR. KSWF has the best chance for conditions to improve to VFR this afternoon. There may be a few spots that fall to IFR cigs tonight. There may also be some gusts into the upper teens to near 20kt on the NE flow, mainly for the NYC terminals and points east. Tricky forecast with respect to precipitation. Some light rain and drizzle remain across some of the terminals this morning, and will carry a TEMPO til 16z. Otherwise, showers will be possible at just about any time today, but confidence on timing and placement of any precipitation too low to keep in the TAFs. .OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY... .Mon-Tue...Improvement to VFR on Monday, remaining VFR through Tuesday. .Tue Night-Wed...Chance of shower/tstm with MVFR conditions. .Thu...VFR. && .MARINE... Have added W LI Sound to the SCA today with NE gusts of 25 and 30 kt being reported. Otherwise, a tight gradient will result in SCA conditions on the ocean waters, E LI sound, and Peconic and Gardiners bays today and continue into Monday. Marginal SCA wind gusts are likely for the remainder of near shore waters. Then, sub-SCA conditions are expected for all the forecast waters early into the middle of next week. Ocean seas could reach SCA criteria again Wednesday night into Thursday. Ocean seas out east may build to SCA levels of at least 5 ft on Wed ahead of an approaching cold front. These elevated seas may linger into Wed night. && .HYDROLOGY... Minor nuisance flooding is possible with any prolonged moderate showers today. Otherwise, no hydrologic impacts are expected through Tue. Tuesday Night into Wednesday...Showers/tstms with heavy rain may be possible with a passing frontal system. With low areal FFG especially over NE NJ, PW increasing to well over 2 inches, and deep layer SW flow indicative of potential training of cells, there is some urban and flash flood potential in this time frame from NYC north/west. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 2 AM EDT Monday for ANZ330-340. Small Craft Advisory until 6 PM EDT this evening for ANZ335. Small Craft Advisory until 2 PM EDT Monday for ANZ350-353-355. && $$

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