Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 230522 AFDOKX Area Forecast Discussion National Weather Service New York NY 122 AM EDT MON MAY 23 2016 .SYNOPSIS... Weakening low pressure remains nearly stationary near Nova Scotia overnight as another low develops off the mid Atlantic coast. This low will approach the region from the south on Monday, passing to the south and east on Tuesday. High pressure will then briefly follow for Wednesday and Thursday with a cold front slipping south of the area Thursday night. The front returns north as a warm front on Friday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Clearing continues overnight with weak subsidence with mainly high clouds across the region. low pressure remains, and weakens, near Nova Scotia overnight. With light winds and clearing skies temperatures across outlying areas have fallen and lowered temperatures a couple of degrees overnight. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... There will be a chance for showers once again north and west of New York City on Monday, with the upper level low still in the vicinity. Another coastal low will develop off the Mid-Atlantic coast and track northeast through Monday night. This will allow the chance for showers to overspread the region into the afternoon and continuing into Monday night. The best chances for precipitation will be late Monday night. Operational models have been keying in on a band of moderate rainfall that may affect the region. However, there is disagreement on when and where this will occur. The NAM shows this band of up to half an inch of rain in a 6 hour period between 2 am and 8 am over Long Island and New York City. GFS shows a quarter of an inch across Eastern Long Island from 8 pm to 2 am, then pivoting into Connecticut and the Lower Hudson Valley after 2 am. The ECMWF looks like a compromise between the two, with less in the way of precipitation. High temperatures will be near normal, in the upper 60s and lower 70s. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... While there is good overall agreement amongst the global models in taking a closed upper low northeast of the area Tue night with its associated sfc low passing east of LI, difference arise later in the week with short wave energy rounding the top of the building upper ridge across the eastern half of the conus. Anomalously warm heights aloft will feature the westward expansion of the the sub-tropical ridge into the eastern third of the country. This all points toward an unseasonably warm, and increasingly humid air mass toward the end of the week. The one caveat here is the aforementioned short wave energy riding over top the ridge Thu night into Fri morning. The 12Z guidance points toward a cold frontal passage Thu night into Fri. Differences arise with how far south it gets and how quickly the boundary returns to the north. The operational GFS and its ensemble mean keep the boundary south of the area through the weekend, while the ECMWF returns it north of the area Fri night. The Global GEM never gets it south of the area. So for the time, the forecast will ease into a solution of dropping the boundary to the south but quickly returning it north on Friday. However, should the other global guidance come around to the GFS, then a cooler forecast will be in store with an easterly flow undercutting the warm air aloft. While we are looking for unseasonably warm conditions Wed-Sun, temps have been nudged down several degrees Fri into Sat. The warmest conditions still remain across the interior with highs in the lower 80s and the 70s at the coast. As for rainfall, the best chance will be Tue with a good chance of showers on the west side of the upper low. There is the potential for some embedded thunderstorms during the afternoon hours. Rainfall amounts with this activity could be up to a few tenths of an inch with isolated higher amounts in any embedded stronger convection. It becomes much more sketchy at the end of the week with ridging aloft and likely capping. The GFS suggests the potential for an MCS at the southern edge of the westerlies The night into Fri with the frontal boundary serving as a lift source. It is much too early at this time to resolve such a feature but to note the potential with the synoptic scale setup. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... Weak high pres remains over the area as low pres remains nearly stationary off the Delmarva into Tue. A lot of variability in the flow thru the taf period. Nearly calm this mrng then ne flow attempts to develop. Sea breeze flow then expected to take over by early aftn. Wind direction will become vrb tngt as the sea breeze circulation weakens. Mainly vfr...however some areas of br will likely result in pockets of mvfr or lower this mrng. Most favorable areas away from the city arpts. .OUTLOOK FOR 06Z Tuesday through Friday... .Late Monday night...mvfr or lower in -ra. .Tuesday...period of mvfr in -shra. .Wednesday-Thursday...vfr. .Thursday night...low chc of mvfr -shra. .Friday...mvfr possible in tstms. && .MARINE... Winds will remain below SCA criteria, with ocean seas running 5 to 6 feet. Seas remain at SCA levels overnight and possibly into early Monday morning. The SCA continues. For Tuesday afternoon into the evening, 5 ft seas could briefly impact the eastern ocean waters as another low passes to the east. Winds and seas will subside Tue night into Wed with high pressure building across the waters. && .HYDROLOGY... Between a quarter and a third of an inch of rain is forecast through Monday night. This should have little if any impact. An additional few tenths of an inch is possible during the day Tuesday, with locally higher amounts possible in any embedded stronger convection. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 AM EDT early this morning for ANZ350-353-355. && $$ SYNOPSIS...JP/DW NEAR TERM...JP/DW SHORT TERM...JP LONG TERM...DW AVIATION...JMC MARINE...JP/DW HYDROLOGY...JP/DW is the U.S. government's official web portal to all federal, state and local government web resources and services.