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Area Forecast Discussion
Issued by NWS Upton, NY
Issued by NWS Upton, NY
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075 FXUS61 KOKX 162157 AFDOKX Area Forecast Discussion National Weather Service New York NY 557 PM EDT Fri Aug 16 2024 .SYNOPSIS... Weak high pressure remains off the east coast through Saturday afternoon as a weak low moves slowly through the Great Lakes. The high weakens Saturday night as the low continues to slowly approach. A warm front slowly lifts north across the region Sunday into Sunday night. A cold front then follows Monday, with a secondary frontal passage into Tuesday. High pressure then builds through the end of the week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Forecast on track this evening. An upper ridge remains from New England into the Mid Atlantic into late tonight with the ridge axis moving to the east toward sunrise Saturday. Meanwhile surface high pressure remains along the coast as low pressure tracks slowly eastward. With the ridge moving east a few light showers may develop across the western sections of the region by morning as some weak upper energy moves into the ridge. With many of the CAMs indicating the possibility have included a slight chance. Lingering smoke aloft should begin to shift eastward overnight as the upper trough begins approaching. With light winds and high humidity into tonight patchy fog will once again be possible across southeastern Connecticut and eastern Long Island. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... The upper ridge moves a little farther into the western North Atlantic Saturday and remains nearly stationary into Saturday night with heights falling across the area with the approach of a shortwave moving into the Great Lakes and upper Midwest regions. With pieces of energy rotating through the eastern trough from time to time scattered showers will remain possible, especially across much of the area by Saturday evening. Have included low chance and slight chances into Saturday night. During Saturday night CAPE will be increasing to around 500 J/kg with some instability and have mentioned a slight chance of thunder across western areas. Any smoke aloft early Saturday will be shifting to the east and into the Atlantic as the upper ridge moves east. && .LONG TERM /SUNDAY THROUGH FRIDAY/... The main period of concern in the long term continues to be Sunday and Monday with potential of locally heavy rainfall. *Key Points* *A warm front slowly moves north and east Sunday into Sunday night followed by a cold front Monday into Monday night. *Locally heavy rainfall in showers and potential thunderstorms is possible Sunday afternoon into Sunday night, mainly from NYC metro on west. *Another round of showers and potential thunderstorms Monday afternoon and evening could bring another round of locally heavy rainfall. *A secondary front may pass Tuesday into Tuesday night followed by high pressure and a cooler/drier air mass mid to late week. An approaching upper level trough, with a frontal system on the leading edge, shifts into the Northeast early next week. The associated warm front lifts through Sunday into Sunday night. The cold front follows Monday into Monday with potential of a weak wave potentially forming along the boundary as it moves through the region. The first round of concern with locally heavy rainfall comes Sunday afternoon into Sunday evening with the warm front. Guidance has been trending slower over the last few days with highest probabilities of organized convection occurring west of the NYC metro in the afternoon and evening. This is likely due to lingering subsidence further east from high pressure off the New England coast. The warm front then shifts north and east could present with a heavy rainfall threat further east overnight, but limited instability and forward speed of the system may preclude the duration of heavy rainfall. This will be refined in future forecasts as the CAMs fully run through Sunday night in the next 24 hours. PWATs look to approach 2 inches late Sunday west of the NYC metro, before slowly shifting eastward Sunday night. WPC has largely maintained a slight risk for excessive rainfall across NE NJ and the Lower Hudson Valley with a marginal into the NYC metro, western Long Island and southwest Connecticut. There is a mainly localized flash flooding risk north and west of the NYC metro. Mainly minor nuisance flooding is possible further east. Another round of showers and possible thunderstorms are likely Monday into Monday night. This will mainly be associated with the cold front, but if a wave of low pressure is nearby, the rainfall could be enhanced somewhere across the region. This is highly uncertain, but there will remain a threat for locally heavy rainfall, minor nuisance flooding, and an isolated flash flooding occurrence. Severe weather parameters continue to look marginal, so not anticipating anything more than an isolated severe thunderstorm occurrence through Sunday night. Monday is a bit more uncertain and may depend on if there is additional heating and destabilization. The timing of the frontal system moving offshore is still somewhat uncertain as the ECMWF/EPS and to some level the CMC are slower to move the system offshore on Tuesday. There may be a secondary frontal passage with the upper trough hanging back, with potential of another low pressure and at least scattered showers lingering on Tuesday. Notably the latest GFS/GEFS and ICON are much faster with the system with high pressure building in and the front offshore on Tuesday. Have maintained a chance PoP Tuesday which is consistent with the latest National Blend. Model guidance is good agreement for troughing aloft to linger over the eastern seaboard Wednesday before the axis of the trough pushing offshore into the end of the week as heights start rising. High pressure will build in Wednesday into the end of the week. Muggy conditions Sunday into Monday should transition to a much less humid air mass mid to late week. Temperatures will mainly be in the 70s to around 80 during the day with 50s and low 60s at night, below normal for mid August. && .AVIATION /22Z FRIDAY THROUGH WEDNESDAY/... Weak high pressure remains in control through tonight with a warm front approaching on Saturday. Showers increase from west to east in the afternoon and early evening with chances of tstms increasing after 20-22z. VFR forecast. Light southerly winds remain through Saturday with speeds remaining at or under 10 kt. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Timing of onset of precip may be off by an hour or two. OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY... Saturday Night: MVFR or lower conditions possible in showers/tstms. 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. Wednesday: VFR. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE... The SCA has been extended into Sunday night on the ocean with potential that it will need to be extended into Monday. Rough seas and long period swells will continue from distant Ernesto Sunday into Monday. Please refer to NHC for official forecasts regarding Hurricane Ernesto. Swells and seas should diminish Tuesday into Wednesday with seas below 5 ft sometime on Tuesday. Otherwise, below SCA conditions are expected Sunday through the middle of the week. && .HYDROLOGY... A tenth to around one-quarter inch of rainfall is possible Saturday night across the Lower Hudson Valley, into Northeastern New Jersey, and New York City., with little to no rainfall east and north. Locally heavy rainfall is possible Sunday afternoon into Sunday night, especially west of the NYC metro and Hudson River. Locally heavy rainfall remains possible across much of the area Monday into Monday night. Rainfall amounts range from around a half inch east to 1-2 inches from NYC metro on NW Sunday through Monday. Locally higher amounts are possible. Some flash flooding is possible across the more flood prone areas of NE NJ and adjacent areas of the Lower Hudson Valley, where a slight risk for excessive rainfall exists. Elsewhere, a marginal risk is in place with right now isolated flash flooding and mainly minor nuisance flooding are possible. No additional hydrological concerns follow Tuesday through late next week. && .TIDES/COASTAL FLOODING... A high rip current risk is in place through Sunday. This is due to SE to S long period swells from Hurricane Ernesto. The high risk will likely need to be extended into Monday. Please refer to NHC for official forecasts regarding Hurricane Ernesto. Ocean seas are forecast to be highest Sunday into Monday, with heights up potentially 7-8 feet. There is potential for high surf along the ocean beaches during this timeframe as well as beach erosion. Minor coastal flooding is possible for the back bays of Long Island and across the CT coast of Western Sound 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 Sunday evening for NYZ075-080- 081-178-179. NJ...None. MARINE...Small Craft Advisory from 10 PM this evening to 6 AM EDT Monday for ANZ350-353-355. && $$ SYNOPSIS...DS/MET NEAR TERM...DS/MET SHORT TERM...MET LONG TERM...DS AVIATION...20 MARINE...DS/MET HYDROLOGY...DS/MET TIDES/COASTAL FLOODING...