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Area Forecast Discussion
Issued by NWS Upton, NY
Issued by NWS Upton, NY
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994 FXUS61 KOKX 161127 AFDOKX Area Forecast Discussion National Weather Service New York NY 727 AM EDT Fri Aug 16 2024 .SYNOPSIS... Weak high pressure remains in place through tonight. A weakening low pressure system then slowly approaches from the Great Lakes this weekend. A warm front then lifts through early Monday as the center of the low redevelops near or over the region. The associated cold front passes through later Monday, with a secondary frontal passage into Tuesday. High pressure then builds in behind the system for mid to late next week. && .NEAR TERM /THROUGH TONIGHT/... The forecast was updated to account for some low stratus heading into SE CT for a few hours this morning before dissipating. The forecast is otherwise mostly on track. Surface high pressure will be accompanied by ridging aloft. The combination of the two will keep us dry today, and with still enough of a ridge aloft tonight, we should be able to get through the night without any showers. Can`t rule out a slight reduction in surface visibility this afternoon mainly NW of the city as per the HRRR smoke forecast, but not enough confidence to include in the forecast. Just expect a hazy appearance of the sky outside of cloud cover. NBM looked good for temperatures through tonight, and dewpoints will be a little higher than what they were yesterday, so it should feel a little more muggy. Patchy fog possible tonight, primarily over CT and eastern LI. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... Low pressure slowly tracks east and weakens across the Great Lakes this weekend. A leading warm front approaches, but is progged to remain west of the forecast area through at least Sunday afternoon. With the slow eastward progression of the system, shower chances will also slowly advance east across the area during Saturday. Likely PoPs don`t begin until late Saturday night, and are probably limited to west of around the Hudson River during Sunday. Eastern portions of LI and CT may end up dry for the entire period. Thunder possible starting Saturday afternoon, but isolated in nature until perhaps Sunday afternoon when chances over the western zones increase. PWATs increase, and chances of at least minor flooding begin to increase Sunday afternoon, mainly over NE NJ and adjacent areas of the Lower Hudson Valley. This will be when more efficient rains could occur as the convective threat increases, and lift is enhanced by both an increasing low level jet and the left-exit region of an upper jet streak in the vicinity. See the hydrology section below for more details. NBM was used for temperatures through the period. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... An approaching upper level trough, with a frontal system on the leading edge, shifts into the Northeast early next week. A warm front lifts through Sunday night into early Monday, with guidance indicating the development of a secondary low which passes near or over the region Monday morning. The attendant cold front tracks through later in the day, with perhaps a secondary front Monday night or early Tuesday. Two primary periods of precipitation from this system look to develop Sunday night into early Monday with the warm front, then additional activity along and ahead of the cold front later Monday. Parameters appear rather tame in terms of severe weather from this system, relatively low instability and shear, though increased moisture with the SW flow will allow locally heavy downpours that could lead to nuisance flooding at times. A subsequent NW flow develops behind it Tuesday, ushering in a much drier air mass. Surface high pressure begins to build in from the Midwest into midweek and should allow relatively dry and tranquil conditions, though the lingering trough aloft could support additional cloud cover in cyclonic flow. Temperatures look to average near, if not slightly below, normals for mid to late August, with highs generally into the upper 70s to around 80, and lows falling back into the 50s and 60s. The national blend was largely followed for this update, with only subtle adjustment. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... Weak high pressure generally remains in control through the TAF period. VFR forecast. Winds light and variable this morning as high pressure moves overhead. The flow goes southerly this afternoon as the high shifts offshore. Speeds remain at or under 10 kt. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Timing of onset of southerly winds may be off by an hour or two. OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY... Saturday: Showers possible with chance of tstms in the afternoon and early evening, particularly for NYC and areas north and west. MVFR or lower conditions possible. Sunday and Monday: MVFR or lower in SHRA/TSRA. Tuesday: Mainly VFR. MVFR or lower possible in any SHRA/TSRA in the afternoon....mainly eastern terminals Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE... Sub-advisory conditions on all waters today. Seas then begin to increase tonight and into the weekend with energy from distant Hurricane Ernesto reaching the coast. Waves will largely be 5-7 feet Friday night through the weekend. Small Craft Advisories are in effect for all the ocean zones beginning tonight and lasting through Sunday. SCA conditions likely persist on the ocean waters through Monday night with elevated swells up to 8 ft. These should lower by late Tuesday, with sub SCA conditions then expected on all waters thereafter. && .HYDROLOGY... Rainfall from Saturday night through Monday is expected to range from around a half inch to an inch for a good portion of the area, however amounts could ramp up towards 2 inches NW of the city in a relatively short distance. Given some uncertainty as to where this tight gradient sets up, confidence isn`t very high regarding the flash flooding potential. Considering that the higher amounts would more likely occur over areas typically more prone to flash flooding (portions of NE NJ and adjacent areas of the Lower Hudson Valley), a marginal to slight risk of flash flooding exists. Best guess right now is that any impacts would not start until Sunday afternoon at the earliest, and would more likely happen any time from Sunday night through Monday night. Can`t rule out flash flooding elsewhere, but any flooding impacts would be more in the minor category. No hydrological concerns follow thereafter through late next week. && .TIDES/COASTAL FLOODING... There will be a high rip current risk today, mainly in the afternoon into early evening. This high risk then continues through Saturday and likely lasts through the entire weekend. This is due to SE to S long period swells from Hurricane Ernesto. Please refer to NHC for official forecasts regarding Hurricane Ernesto. Ocean seas are forecast to be highest Sunday into Monday, with heights up to 8 feet. There is potential for high surf along the ocean beaches during this timeframe as well as beach erosion. In addition, the high risk of rip currents will likely extend through early next week. Minor coastal flooding is possible early next week during high tide cycles Sunday through Tuesday as swells build and astronomical tides increase due to the full moon on Monday. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...High Risk for Rip Currents through Saturday evening for NYZ075-080- 081-178-179. NJ...None. MARINE...Small Craft Advisory from 10 PM this evening to 6 PM EDT Sunday for ANZ350-353-355. && $$ SYNOPSIS...JC/DR NEAR TERM...JC SHORT TERM...JC LONG TERM...DR AVIATION...DR MARINE...JC/DR HYDROLOGY...JC/DR TIDES/COASTAL FLOODING...