506
FXUS61 KOKX 052022
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
422 PM EDT Mon May 5 2025

.SYNOPSIS...
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A weak frontal boundary will remain in close proximity to the area through Tuesday with high pressure tracking across the Canadian Maritimes. At the same time, a broad area of low pressure over the Ohio Valley will track slowly east. Between the two, bands of rain will work in off the ocean. The front gradually lifts back the north on Tuesday, while low pressure approaches from the west. Weak low pressure will then slide northeast through the area on Wednesday. A cold front will approach from the northwest on Thursday and stall nearby Thursday night as low pressure develops along it over the Mid Atlantic region. Coastal low pressure will track over or just southeast of the region Friday into early Saturday, before heading up the New England coast. Another cold front will approach from the northwest on Sunday.
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&& .NEAR TERM /THROUGH TUESDAY/...
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System thus far has underperformed the last 24h and guidance and the CAMs continue to struggle with the rain bands rotating in off the ocean. Latest consenus has shifted the axis of heaviest rain a bit farther east, emphasizing eastern LI and much of southern CT as the likely recipients. An easterly LLJ of 40kt will lift across the area this evening, enhancing orographic lift with to 3 inches of rainfall still possible across the inland areas of CT, minus slightly lower amounts in the CT River Valley. The Lower Hudson Valley, NYC, and NE NJ can expect an additional quarter to one-inch, possibly up to 1.5 inches across some of the higher elevations north and west. Latest CAMs take the current area of rain and lift it north through early this evening. There will likely be a break in the action before another band moves in from the south. The focus is mainly from NYC and east. Instability remains marginal and will gradually increase overnight into Tuesday as the precipitation takes on a more convective look. SPC HREF PMM hourly and three-hourly amounts remain below FFG through tonight with storm total amounts as high as 3 to 5 inches across the higher elevations in CT. Based on performance thus far and uncertainty with the band placement, these amounts are likely to be localized. As for the latest NBM, probability for more than an inch of rainfall is 60 to 80 percent. WPC maintains a slight risk of excessive rainfall across the area through the overnight, so can`t completely rule out isolated flash flooding. Once again though, emphasis on location would be across interior CT. Easterly winds will veer around to the SE tonight with mild conditions. Lows will be in the mid and upper 50s. Then onshore flow and high dew point air will also result in fog, some of which could be locally dense. On Tuesday, a bit more instability is expected, especially west of the NYC metro in the afternoon with the potential for some partial clearing. However, there still looks to be enough of a marine influence to keep it more elevated and unlikely to reach severe limits. With the upper low approaching, impulses will move in from the south with additional bands/pockets of rain, but looking less organized than what is expected tonight. Localized amounts up to an inch will be possibly with potential training of cells in a deep-layered southerly flow. Minor nuisance flooding will continue to be possible. Highs Wednesday will be warmer in the mid 60s to around 70. This closer to normal.
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&& .SHORT TERM /TUESDAY NIGHT/...
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Widely scattered to scattered showers can be expected Tuesday night with emphasis to the west of NYC early in the evening where the airmass will be most unstable. The upper low will near the area by daybreak Wednesday. Expect some additional fog with a southerly flow and high dew point air in place. Lows will be in the 50s, which is about 5 to 10 degrees above normal.
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&& .LONG TERM /WEDNESDAY THROUGH MONDAY/...
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Good model agreement in persistent cutoff upper low to the SW of the area the last few days shearing NE through the region on Wed, ahead of a digging northern stream trough sliding from Ontario into Quebec. This trough will slide into the NE US for late week, with good agreement in another closed low developing at its based in the to the SW the region Thu Night/Friday and then pivoting ne through Saturday. At the surface, the stalled frontal system over the region should lift ne thru the area Wed into Wed eve, with drying conditions Wed Night into Thu AM. Cold pool aloft plus daytime heating should generate enough instability for sct to numerous shra/tstms late Wed AM into Wed eve ahead/along surface wave/frontal trough, particularly N&NW of NYC. Drying conds in wake of the departing low appears short lived, as the next cold front approaches the region Thu aft/eve. Isolated aft shra/tsra activity possible in this weakly unstable environment. Good agreement in sfc cyclogenesis over the Mid Atlantic region along the cold front on Thu Night into Friday as the digging northern stream trough phases with southern jet and closes off at its base across the Central Appalachians. Resultant strengthening coastal low pressure will bring increasing likelihood of overrunning rain Thu Night into Fri AM, with potential for a period of moderate to heavy rain Fri into Sat AM with deep layered lift and convergence of Gulf/sub-tropical moisture feed over the region as low pressure tracks over or se of the region. Improving conditions Sat aft/night in wake of low pressure and closed low. Subsequent shortwave likely crosses with cold frontal passage Sun/aft eve, with seasonable conditions to follow for early next week with Canadian high pressure building into its wake and gradually rising heights. Temps near to slightly above seasonable for Wed/Thu, falling to a few to several degrees below seasonable Fri/Sat with low pressure affecting the area, then moderating back to slightly above seasonable for Sun into early next week.
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&& .AVIATION /19Z MONDAY THROUGH SATURDAY/...
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Frontal boundary remains stalled within the region through the TAF period. Mainly IFR to LIFR forecast with low clouds, fog, and periods of rain expected through the TAF period. Some terminals could see brief VLIFR (mainly overnight and for outlying areas) or MVFR conditions at times. MVFR conditions would likely come in improvements in visibility with lighter rain or a respite from the rain (though any moderate to briefly heavy rain would be associated with lower visibility, keeping it in the IFR to LIFR range). Winds are easterly around 10 kt. Gusts, mainly for the sound terminals (KLGA, KBDR and KGON). Occasional gusts 15 to 20 kt elsewhere, diminishing this evening. Southeasterly flow expected Tuesday at around 10 kt. ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Categories will fluctuate between LIFR and MVFR through the TAF period. .OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY... Tuesday afternoon and night: Rain/showers and IFR. Possible thunderstorms. SE gusts around 10 kt, with gusts up to 15 kt. Wednesday: Chance of MVFR or lower with and a chance of showers and slight chance of thunderstorms. Thursday: MVFR possible with a chance of showers, mainly at night. Friday: MVFR possible with a chance of showers. A slight chance of thunderstorms. Saturday: Mainly VFR, except MVFR or lower possible in slight chance of showers. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90
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&& .MARINE...
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Marginal SCA conditions for seas around 5 ft will continue through the day Tuesday in an E/SE flow. This may need to be extended into Tuesday night, but confidence is low at this time. Marginal 4-5 ft ocean seas possible Wed into Wed night in mainly a residual E/SE swell, with sub SCA conditions likely on Thu under a weak pressure gradient. Next potential for SCA conditions Fri/Sat on all waters with coastal low pressure. Low prob for gales on the ocean in E/SE flow ahead of the low if stronger coastal development evolves.
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&& .HYDROLOGY...
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An additional 1 to 3 inches of rainfall is expected through Tuesday with the upper end forecast across interior CT due to an easterly LLJ this evening. Localized higher amounts are possible. WPC has the area under slight risk of excessive rainfall with isolated flash flooding possible. There is the potential for a period of moderate to heavy stratiform rain for Fri into Sat AM. NBM probability of 1" in 24 hr is at 20%, with less than 10% prob of 2" in 24 hr.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Dense Fog Advisory until 8 PM EDT this evening for ANZ350-353- 355. Small Craft Advisory until 6 PM EDT Tuesday for ANZ350-353. Small Craft Advisory until 6 PM EDT Tuesday for ANZ355.
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&& $$ SYNOPSIS...NV/DW NEAR TERM...DW SHORT TERM...DW LONG TERM...NV AVIATION...JP MARINE...NV/DW HYDROLOGY...NV/DW