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FXUS61 KOKX 010915
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
515 AM EDT Thu May 1 2025

.SYNOPSIS...
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High pressure remains in control today as the center shifts off the New England coast. A warm front approaches tonight and lifts through the region into Friday morning. A cold front then slowly approaches Saturday into Saturday night, with a wave of low pressure developing along it. This frontal system may linger near the area through early next week, as a cutoff upper low develops to the southwest.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Upper ridge axis shifts overhead today as surface high pressure drifts off Cape Cod. Dry conditions expected thru the day. Winds veer SE into the afternoon as the high moves offshore, and the resultant onshore flow limits temperatures along the coast with SSTs still in the low 50s. Highs here top out in the upper 50s to mid 60s, with lower 70s expected away from the marine influence in the LoHud Valley and NE NJ. As the high shifts further east tonight, low pressure tracks into the Great Lakes with the associated warm front approaching the local region. This introduces increased cloud cover, along with the chance for showers late tonight into Friday morning. Can`t rule out a spotty thunderstorm with this activity either, but coverage overall appears limited, and some locales may not see precipitation. The front lifts through toward daybreak, and could see areas of fog break out in its wake into Friday morning as the shower activity exits.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
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A more active pattern looks to develop in this period, with an increasing likelihood of unsettled conditions persisting thru at least early next week. Behind the warm fropa early Fri AM, a much warmer air mass advects in on deep SW flow. Any fog around in the morning burns off and S/SW flow and deep mixing allow temps west of the Hudson to rise into the 80s, or a good 15 degrees above climo for early May, while coastal areas remain in the 60s to around 70. As the East Coast ridging shifts farther offshore, several northern stream shortwaves dig a trough from the Canadian Plains into the Mississippi River Valley Friday into Saturday. The pre-frontal trough approaches western portions of the area Friday aft/eve, bringing the potential for scattered showers and thunderstorms, mainly for NYC and points N&W in a weakly forced, but marginally unstable/modest shear environment. A more stable airmass along the coast will likely have any convection dissipating as it overspreads the coast and encounters this environment. Conversely, could be dealing with stratus/fog development for southern and eastern coastal areas late Friday into Sat with moist onshore flow over cold waters (lower 50 SSTs). CSU MLP still indicates a marginal severe threat, which seems conditionally possible. Perhaps a better chance for organization of scattered shower and thunderstorm activity ahead of the approaching cold front Saturday afternoon and evening for NYC and points NW once again with approach of northern shortwave in a marginally unstable and strong deep layer shear environment. Although airmass is similar on Friday to Saturday, potential for more in the way of convective debris on Saturday limiting full insolation. Better agreement amongst global guidance relative to this time yesterday, with most ensemble members now signaling a cutoff low closes off to the SW of the region this weekend thru early next week as an omega blocking pattern develops across the Eastern US into Western Atlantic. The result being the aforementioned cold front stalling to the west of the region and strong Canadian maritime high to the NE leading to a persistent Atlantic subtropical moisture flow into next week.
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&& .LONG TERM /SUNDAY THROUGH WEDNESDAY/...
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The combo of a cutoff upper low developing over the Ohio Valley and an amplifying upper high over the western Atlantic will be the main drivers of sensible wx for the area. A feed of subtropical Atlantic moisture into the area between these two systems will keep us unsettled through the period and offer the likelihood of some periods of heavier showers, whose exact timing and rainfall amts are still uncertain. Latest guidance suggests best time frames for heavier rainfall may be Sunday night into Mon morning and more so Tue into Tue night. Latest ECMWF ensemble is focusing in more on Tue, showing higher probabilities of 1-2 inches in 24 hours in that time frame, and 90th percentile QPF of over 3 inches.
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&& .AVIATION /09Z THURSDAY THROUGH MONDAY/...
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High pressure passing to the north will move off the coast this afternoon. A warm front will approach tonight. VFR for most of the period, with generally light N-NE winds becoming E this morning and then SE around 10 kt this afternoon. With the approach of the warm front, some MVFR cigs should move into the NYC metro area and across Long Island after midnight. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... No unscheduled AMD expected. .OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY... Late tonight: IFR cond likely/LIFR possible with the approach of the warm front. Scattered/numerous showers and an isolated tstm possible. Friday: MVFR or lower cond to start should improve to VFR by late morning after warm fropa, then showers/tstms possible in the afternoon and at night. S winds G15-20 kt in the afternoon. Saturday: MVFR or lower cond possible with chance of showers/tstms. thunderstorms. S winds G15-20kt. Sunday: MVFR or lower cond possible with chance of showers/tstms. Monday: MVFR or lower cond possible with chance of showers. E-NE winds G15-20kt. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90 0
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&& .MARINE...
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Winds and seas remain low through tonight with high pressure near the region. Marginal S/SW SCA gusts possible on the ocean Fri aft/eve and then once again Sat aft/eve with approach of cold front. More confidence in ocean seas building to 5 ft during this time, lingering into Sunday based on persistent S/SW flow. Residual 5-ft ocean seas Sunday morning should subside by afternoon. Increasing E flow on Mon may bring minimal SCA cond to the ocean waters, with E winds gusting to 20-25 kt and seas building to 5 ft.
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&& .FIRE WEATHER...
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Light southeasterly flow 5 to 10 mph develops by late morning or early afternoon today. RH values drop to 25 to 35 percent by late morning, increasing above 40 percent along the coast by the afternoon with strengthening onshore flow. A wetting rain is possible overnight into Friday.
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&& .HYDROLOGY...
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There is potential for heavy rain of over 2 inches next week, but timing/duration of any heavier periods of rain and exact amounts remain uncertain.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...BG/DR NEAR TERM...DR SHORT TERM...DR LONG TERM...BG AVIATION...BG MARINE...BG/DR FIRE WEATHER...DR HYDROLOGY...BG/DR