Area Forecast Discussion
Issued by NWS Upton, NY

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454 FXUS61 KOKX 241134 AFDOKX Area Forecast Discussion National Weather Service New York NY 634 AM EST Sat Feb 24 2018 .SYNOPSIS... Weak low pressure tracks across the region late today into this evening. A warm front moves towards the region tonight, with a frontal system affecting the region Sunday. High pressure builds from the Midwest Sunday night and remains in control through the middle of next week. A low pressure system may approach for the end of the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Near zonal upper flow today, with northern stream shortwave tracking from Ontario into Quebec, and southern stream energy rotating around southern ridging. At the surface weak high pressure over the region this morning, will give way to approach of low pressure/s from the Tennessee/Ohio Valley along a stalled warm front. This will spell a shot of rain from SW to NE this afternoon into evening. Forcing with this system is not too strong, so expecting overall a a light rain event. Temps will run above seasonable with mild airmass in place, Generally upper 40s to lower 50s. If several hours of sunshine are experienced this morning, temps could rise into the lower to mid 50s. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... Phasing Sub-tropical and Pac Jet Energy will lift towards the Great Lakes and NE US tonight into Sunday, with a strong mid- level shortwave tracking through the Great Lakes tonight into Sunday Morning. At the surface, strengthening low pressure will take a similar track, eventually stacking under closing upper energy across northern Ontario by late Sunday. It trailing cold front will approach on Sunday with warm front lifting towards the region late tonight into Sunday, and signal for triple point low tracking over NYC/LI or just south Sunday aft/early Sun evening. Expect increasing likelihood for rain from w to e late tonight as WCB and divergent upper flow transport and lift a +3-4 std pwat airmass into the region. This rain will be moderate to heavy late tonight into Sunday as moisture/lift is focused to the north of the warm front and in vicinity of the triple pt low late tonight through Sunday. 1 to 1 1/2 inches of rainfall likely areawide, with locally higher amounts from orographic enhancement. Cold air damming and evaporational cooling early Sunday morning will likely have temps falling into the mid 30s across interior valleys, perhaps localized lower 30s. At this point threat for any freezing rain looks to be low, brief and localized. Otherwise, temps will likely be hard pressed to rise into the lower 40s across the interior, particularly valleys, on Sunday, while coastal areas should be able to rise into the mid to upper 40s. S LI could flirt with 50 degrees if warm front can lift north. Shortwave energy pivots NE Sunday evening with the triple pt low and cold front pushing east, and rainfall tapering off. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... The CONUS pattern of troughing in the west and ridging east of the Rockies looks to continue into next week. The upper pattern then appears to transition mid to late week next week as a closed low pres system moves onshore in California early, continues into the Plains mid week, and then possibly to the east coast by late week. Uncertainty abounds in the evolution of this upper energy as the week progresses. In terms of sensible weather, dry weather returns Sun night as low pres departs and high pres builds from the Midwest. The high will remain in control through the middle of next week, resulting in a continuation of above normal temperatures. Rain chances will begin to increase Thu as a WAA pattern ensues, although due to the aforementioned uncertainty in the upper pattern, precip could very well hold off until Thu night. Predictability is low on p- type this far out, but lack of cold air supply would favor liquid vs frozen at this point. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... High pressure will build to the north today as a front stalls to the south. The front will lift back toward the area as a warm front late today into tonight as the high pulls away. Still seeing IFR conds at KJFK/KEWR/KGON and MVFR elsewhere. Drier air should start moving into the area, early this morning, with conds improving to VFR at about the same time sfc winds shift from WSW to WNW. Light rain with ocnl MVFR cigs may be possible late this afternoon, but more widespread MVFR conds appear more likely after 00Z. .OUTLOOK FOR 06Z SUNDAY THROUGH WEDNESDAY... .Late tonight and Sunday...Rain with IFR conds. E-SE winds 10-15kt with G20-25kt. .Sunday night...Chance of rain with MVFR conds mainly KISP/KGON, otherwise VFR. .Monday through Wednesday...VFR. && .MARINE... Sub-SCA conditions are expected through this evening with weak high pressure moving across the region. Easterly winds will increase late tonight into Sunday morning, with widespread SCA conditions expected. Potential for a period of marginal gale gusts during this time on the ocean, with seas building to 6 to 10 ft. Winds subside Sun Night with high pressure building in, but SCA ocean seas will likely take till Monday to subside. Sub SCA conds thereafter with high pressure building from the west. && .HYDROLOGY... Rainfall late today through Sunday is expected to produce around 1 to 1 1/2 inches of rain, much of it on Sunday. There could be some locally higher amounts, especially in any areas of orographic lift. With saturated grounds, minor poor drainage flooding is possible on Sunday. && .TIDES/COASTAL FLOODING... Easterly SCA winds will likely result in 1 to 1 1/2 ft surge and 3 to 4 ft waves into Western LI Sound, which may result in some localized minor flood/wave splashover in vulnerable areas with Sunday morning high tide. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from 1 AM to 6 PM EST Sunday for ANZ330- 335-338-340-345. Gale Watch from late tonight through Sunday afternoon for ANZ350-353. Small Craft Advisory from 1 AM Sunday to 7 AM EST Monday for ANZ355. && $$ SYNOPSIS...NV NEAR TERM...NV SHORT TERM...NV LONG TERM...24 AVIATION...Goodman MARINE...NV HYDROLOGY...NV TIDES/COASTAL FLOODING...NV EQUIPMENT...

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