Area Forecast Discussion
Issued by NWS Upton, NY
Issued by NWS Upton, NY
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072 FXUS61 KOKX 251742 AFDOKX Area Forecast Discussion National Weather Service New York NY 142 PM EDT Wed Sep 25 2024 .SYNOPSIS... High pressure across the Northeast continues to weaken and slowly giving way to a frontal system that will move across the area Thursday into Thursday night. High pressure will then gradually build in from the north through early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Rain chances have been adjusted a little based on the latest radar obs and CAMs. The forecast is otherwise on track. A longwave trough over the mid section of the country will continue to split as the northern energy heads tracks across the Great Lakes today, and the southern closed low becomes cutoff over the Tennessee Valley. The associated frontal system preceding these features will ever so slowly work east with warm advection showers gradually working into the area from SW to NE today. The better chances for rain will reside to the north and west of NYC along with the better thermal forcing. Otherwise, expect mostly cloudy skies with an easterly flow. This should keep highs mainly in the 60s, which is several degrees below normal. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... There have been some differences the last 24h, most notable is the increase in rainfall amounts across the area. With the ridge over the western Atlantic and the better lift with the incoming upper trough to the north and west, there has been uncertainty as to how far south and east the heavier rainfall would get. The trend the last 24h has been for more rainfall across the region. Warm advection showers will continue through tonight into Thursday with the best chances remaining north and west of the NYC. A warm front will pass through Thursday afternoon, followed by the cold frontal passage at night. Airmass gradually destabilizes on Thursday with dew points getting well into the 60s with highs in the 70s. Not looking at a severe weather threat, but any deeper convection will briefly enhance rainfall rates. Rainfall amounts are forecast to range from a couple of tenths along the coast, to in excess of a half inch across interior NE NJ, the Lower Hudson Valley, and interior SW CT. These amounts are likely to change some as the forecast area resides on the SE side of the heavier rainfall axis. Subtle shifts will make a difference. The other question is how much convection with the actual cold front will make it down to the coast. Latest CAMs do show a weakening trend as would be expected due to the time of day. As for temperatures, it will be above normal during this time and quite humid with highs in the 70s and lows in the 60s. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... The area remains sandwiched between a departing trough to the east and a cutoff low pressure system over the Mississippi Valley Friday night and into Saturday with a ridge building generally overhead between these two systems. At the surface, a high pressure system drops down out of Canada and moves over much of the Northeast US. This should largely result in dry conditions for much of the area over the weekend. Global model trends recently have allowed for a subtle weakening of the ridge over the area which results in perhaps some shower activity approaching the area from the southwest during the weekend, but for now kept PoPs at a minimum for the southwestern most areas as consensus at this time seems to be drier than not. The cut off low over the Southeast US will approach the area as it becomes reconnected to the large scale flow which may result in a better chance of shower activity during the beginning of next week, but most models weaken the low to the point where any showers will be light and widely scattered as the low shifts off the US coast to the south of the CWA. Another frontal system looks to approach from the west providing for another chance of showers by the middle of the week. Temperatures will be generally seasonable through the extended period. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... High pressure gradually weakens as a frontal system approaches into tonight. Mainly MVFR thru the day. IFR cigs possible by evening, becoming likely for most terminals toward and after 6Z Thu. Return to MVFR by late morning, but cigs may hang near 3 kft much of the day. Scattered -SHRA approaches from the west, with rain chances beginning to increase after 18Z, but mainly after 00Z for the NYC and eastern terminals. Western terminals (KSWF, KHPN) expected to have higher likelihood of more widespread SHRA activity. KGON may remain entirely dry. Additional showers, with potential thunderstorms, persist through the day Thursday, though timing and coverage is low confidence at this point. SE flow 10 to 15 kt with gusts up to 20 kt thru remainder of the day. Winds then gradually shift southerly overnight into Thursday morning. Similar speeds on Thursday. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Unscheduled amendments likely for changing flight categories due to timing of cigs and presence of -SHRA through TAF period. OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... Thursday PM: MVFR or lower with showers/thunderstorms at times. Friday: MVFR or lower in the AM with low stratus, becoming VFR by afternoon. Saturday-Monday: Mostly VFR. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 && .MARINE... Long period easterly swells from a slowly departing offshore low will to continue to produce advisory level seas on the ocean through tonight with waves possibly remaining near 5 feet through Thursday evening. Ocean seas likely fall below 5 feet Thursday night into Friday as swells continue to diminish and a northerly flow develops behind a cold front. Thereafter, sub- SCA conditions are expected on all waters through the beginning of next week. && .HYDROLOGY... There are no hydrologic concerns through early next week. && .TIDES/COASTAL FLOODING... The high risk of rip currents continues through Thursday due to continued long period easterly swells. Some improvement is expected on Friday as swells gradually diminish. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...High Risk for Rip Currents through Thursday evening for NYZ075-080- 081-178-179. NJ...None. MARINE...Small Craft Advisory until 6 AM EDT Thursday for ANZ350-353- 355. && $$ SYNOPSIS...DW/MW NEAR TERM...JC/DW SHORT TERM...DW LONG TERM...MW AVIATION...DR MARINE...DW/MW HYDROLOGY...DW/MW TIDES/COASTAL FLOODING...