Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 250532 AFDOKX Area Forecast Discussion National Weather Service New York NY 132 AM EDT Tue Oct 25 2016 .SYNOPSIS... High pressure slowly builds in from southern Canada through Wednesday. The high moves east on Wednesday giving way to a frontal system Thursday into early Friday. Another frontal system impacts the area this weekend, followed by high pressure Monday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... A 700-500 hPa shortwave will pass by overnight. At the minimum will help to keep boundary layer well mixed and winds up. Could also see some clouds over Far NW zones before low level downslope takes over farther east. Temperatures continue to fall of not as fast as forecast in urban and rural zones. As a result, have tweaked lows up a few degrees in most places - consistent with latest trends in guidance and observations. Based on expectation of winds staying up and lows not quite as cool/cold - plus dewpoints falling off faster than expected, have removed patchy frost from the forecast overnight. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... Upper trough over northern New England and the Canadian Maritimes will slowly translate east Tuesday into Tuesday night. Cold advection will continue with 850 temperatures dropping to -4 to -6C. A similar subsidence inversion to Monday will likely be present per BUFKIT soundings around 800 hPa. There appears to be enough moisture during the day trapped beneath this inversion to help develop some stratocumulus. Sky conditions start the day partly cloudy, with the potential to go mostly cloudy at times in the afternoon. Gusty NW winds are once again forecast from the strong pressure gradient between the low to the northeast and building high to the west. Mixing up to near 800 hPa should allow for gusts 25 to 30 mph in the afternoon, strongest near the coast. High temperatures will end up well below normal for this time of year in the upper 40s and low 50s. Cold advection continues Tuesday night, but ideal radiational cooling conditions are not anticipated as winds will remain up. However, the coldest airmass of the season will be in place and temperatures should be able to fall to near 30 degrees across the interior, and middle and upper 30s most elsewhere. Have therefore issued a freeze watch across all of interior southern CT, the Lower Hudson Valley excluding Orange county where the growing season has ended, and interior NE NJ. Elsewhere, do not think a widespread frost will occur due to the winds and overall dry airmass in place. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Trough finally departs, allowing weak ridge to briefly build Wednesday. Next shortwave tracks across the Great Lakes Region Wednesday night, and slows as it closes off Thursday and Thursday night over the northeast. The pattern remains progressive as yet another shortwave follows this weekend. Some differences in the global models are noted with regard to timing, and speed of these systems as they move west to east. At the surface, high pressure builds overhead, then moves east late Wednesday/Wednesday night. A warm front approaches Wednesday night from the west as low pressure tracks across the Great Lakes and across PA/western NY. The low and associated frontal boundary slows as it moves over the area Thursday, passing to the east Thursday night into Friday. High pressure builds to the south as another low moves across the Great Lakes Region Saturday, passing to the north early Sunday. Some questions arise on Monday with upper levels, and thus surface features at that time. Could be unsettled. As for sensible weather, WAA showers move in late Wednesday night and through the day Thursday. Enough cold air ahead of the WAA, and time of day being early morning could result in some snow showers briefly NW zones. Some accumulations are possible across higher elevations before a change to plain rain occurs. Once this area of showers moves east Thursday night, generally dry weather is expected ahead of next best chance Saturday ahead of the upstream shortwave. After a chilly start to the period Wednesday, temperatures will be near normal in this progressive pattern, with no large swings in temperatures expected. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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VFR as high pressure builds over the region. NW flow with occasional gusts to 20kt possible from 11-14z. Gusts becoming more frequent after 14z. Direction should prevail north of 310 magnetic for the city terminals, but could prevail at or south of 310 magnetic at KEWR. .OUTLOOK FOR 06Z WEDNESDAY THROUGH SATURDAY... .TUE NIGHT...VFR with diminishing NW winds. .WED...VFR. NW-NNW G20KT possible near the coast. .THU...MVFR conditions likely in rain. IFR conditions possible at night. SE winds 10-20KT. .FRI...VFR. W-NW winds G25-30KT. .SAT...VFR. Chance of rain. SW winds G15-20KT.
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&& .MARINE... Made minor changes this update to reflect the latest trends in observations and guidance. The forecast appears on track. Strong pressure gradient over the waters will continue through Tuesday with SCA conditions. Winds may briefly weaken on near shore waters tonight before increasing again during the day on Tuesday. The SCA remains in effect through Tuesday evening and may need to be extended into Tuesday night on the ocean waters as winds are likely to remain around 25 kt. Gusty NW winds will diminish Wednesday as high pressure builds. Winds shift around to the east, then SE Wednesday night as Thursday as the high departs, and a warm front and low pressure system approaches. As the low passes by Friday, winds shift back around to the west/nw and increase behind the departing low. These winds back yet again to the west/SW ahead of next low pressure system Saturday. Ocean seas subside and remain well below 5 FT Wednesday, Wednesday night and into Thursday. Seas build once again ahead of and behind the low pressure system that impacts the waters later Thursday, and these rough seas continue Friday night, then subside Saturday. && .HYDROLOGY... Dry weather is forecast through Wednesday. Low pressure impacts the area Thursday and Thursday night. Forecast QPF is expected to produce anywhere from 1/2 to 3/4 of an inch of rainfall. Local amounts over an inch are possible. No hydrologic impacts expected at this time. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...Freeze Watch from late tonight through Wednesday morning for CTZ005>008. NY...Freeze Watch from late tonight through Wednesday morning for NYZ068>070. NJ...Freeze Watch from late tonight through Wednesday morning for NJZ002-004-103-105-107. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ330- 335-338-340-345-350-353-355.
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&& $$ SYNOPSIS...DS/PW NEAR TERM...Maloit SHORT TERM...DS LONG TERM...PW AVIATION...JC MARINE...Maloit/DS/PW HYDROLOGY...DS/PW is the U.S. government's official web portal to all federal, state and local government web resources and services.