Area Forecast Discussion
Issued by NWS Upton, NY

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545 FXUS61 KOKX 111324 AFDOKX Area Forecast Discussion National Weather Service New York NY 924 AM EDT Sat May 11 2024 .SYNOPSIS... High pressure builds in from New England today, then another frontal system tracks through Saturday night into Sunday. High pressure briefly returns Sunday night. High pressure then moves offshore early next week followed by a low pressure area moving across midweek. Weak high pressure returns thereafter towards the end of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Forecast updated to reduce cloud cover this morning as much of the area is clear. The only areas with some clouds leftover are out near MTP and low clouds across western Orange County. These low clouds will diminish through 11 am, but the clouds may linger near or just east of MTP with offshore low pressure. Otherwise, a weak high ridges down from New England today with a mid level ridge overhead. These features are all within a larger mean upper level trough over eastern North America. The sunshine today will be brief as another trough digs southeastward from the Great Lakes. Clouds will begin increasing from west to east this afternoon and evening. Cooler air will remain in the region today with highs only expected to reach low-60s. Some near the NYC metro may reach the mid-60s while other the immediate coast of Long Island and Connecticut may only reach the upper-50s. These temperatures are about 5-10 degrees cooler than average.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... With troughing increasing from the west with an approaching frontal system in the Great Lakes, cloud cover is expected to increase Saturday evening into Saturday night. PWATs of 1"+ will also be advected in from the west with positive vorticity advection and warm air advection aloft both occurring, aiding in the formation of clouds and eventual rain. The trough will guide a weakening frontal system into our area overnight Saturday with an occluded front. Rainfall will start in the west overnight and spread eastward toward daybreak and into the morning. Given the weakening nature of the system, most of the rainfall will likely occur over far western sections of the area with much lighter precip expected for the rest of the CWA due to weaker forcing. Some may only pick up a trace or even remain dry (in eastern areas), while those in far western sections of our CWA could see around a quarter inch. No thunderstorms are expected due to a stable environment. Temperatures will be cooler on Sunday from the influence of the trough, cloud cover and rain. Highs are expected to be in the mid- 50s, around 10-15 degrees below seasonal norms. Expecting slow improvement Sunday afternoon and evening as high pressure returns once again with weak ridging aloft increasing from the west. Given the weak high taking over and the weak departing low, the pressure gradient will be weak, meaning mostly light winds Sunday night. And with the high pressure clearing clouds, could expect some weak radiational cooling. Lows are forecast to be in the mid/upper-40s with the LI Pine Barrens and interior areas in the low- 40s. && .LONG TERM /MONDAY THROUGH FRIDAY/...
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In the mid levels, ridging early next week will be followed by a trough moving in for midweek. Model differences with timing and evolution of trough with ECMWF showing a cutoff low. ECMWF keeps a slower movement of the cutoff low while the GFS and Canadian models depict a faster more progressive trough shifting more east of the area towards the end of next week. At the surface, high pressure based in the Atlantic will allow for more southerly flow to develop early next week. Low level warm air advection is forecast with a warming trend to daytime temperatures from Monday to Tuesday. More easterly component of flow develops for midweek as low pressure approaches from the west. Like the mid levels, differences become more apparent in model solutions regarding the speed, location and strength of the low. ECMWF lingers the low nearby for Thursday and Thursday night while the GFS and Canadian models show the low moving farther east of the region. Weak high pressure follows for Thursday into Friday. Next substantial rain event depicted in the general Tuesday to Wednesday night timeframe. Tuesday night and Wednesday could present some embedded thunderstorms, with a slight chance with elevated instability and colder air aloft moving in. Temperatures mainly near to above normal during the long term.
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&& .AVIATION /13Z SATURDAY THROUGH WEDNESDAY/...
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Weak high pressure initially will give way to an approaching weak frontal system tonight into early Sunday. Mainly VFR conditions are expected through the TAF period. N to NE winds will be near 5 kts initially this morning. Winds then become more east this morning with more southeast winds developing this afternoon into tonight. Wind speeds will be generally near 5-10 kts. NYC terminals a few kts higher with max wind speeds closer to 12-13 kt at times this afternoon. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Timing of wind shift from NE to SE this afternoon may be off by a few hours. OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY... Sunday: Chance of MVFR or lower in showers. Monday: Mainly VFR. Isolated showers possible mainly north of NYC terminals. Tuesday: MVFR or lower in showers. T-storms possible at night. S-SW wind gusts 15-20 kt. Wednesday: MVFR or lower in showers and t-storms. SE to NE wind gusts 15-20 kt. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90
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&& .MARINE... Winds and seas should remain below SCA levels this weekend. Mainly below SCA conditions forecast Monday through Tuesday with more probable SCA conditions for midweek. && .HYDROLOGY... No significant hydrologic problems anticipated. && .TIDES/COASTAL FLOODING...
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Many locations are expected to fall short of minor coastal flood benchmarks for high tide cycles tonight. However, the South Shore Bays of Nassau County NY could have some locations that touch or slightly exceed their minor coastal flood benchmarks. A coastal flood statement has been issued for Southern Nassau County between 9PM EDT this evening and 1AM Sunday EDT overnight. No additional coastal flooding is anticipated Sunday into next week as astronomical tide levels continue to subside.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JM/BR NEAR TERM...BR/DS SHORT TERM...BR LONG TERM...JM AVIATION...JM MARINE...JM/BR HYDROLOGY...JM/BR TIDES/COASTAL FLOODING...