Area Forecast Discussion
Issued by NWS Upton, NY

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338 FXUS61 KOKX 091643 AFDOKX Area Forecast Discussion National Weather Service New York NY 1143 AM EST Fri Dec 9 2016 .SYNOPSIS... A series of cold fronts will move across through Saturday. High pressure will briefly build in Saturday night. Then an active winter pattern will set up for next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Updated forecast mainly for hourly and high temperatures. High temps were adjusted upward to account for downslope warming. Highs generally around 40 with wind chills around 30 this afternoon. Brisk NW flow will continue today, gusting to 30-35 mph with the highest speeds in/near NYC.. Satellite and radar show lake effect clouds and snow showers moving across upstate/central NY and northern/central PA in advance of a reinforcing cold front that should move into the area late this afternoon. Think main thrust of this activity will be north and east of NYC where isolated to scattered flurries/snow showers are expected. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Front should clear the area by evening, with precip chances diminishing tonight and skies clearing. It should however remain brisk, with temps dropping to the upper teens inland/Long Island Pine Barrens and into the 20s elsewhere. As another upper level disturbance and weak front approach and bring mostly cloudy skies, do not expect much recovery in the way of high temps, with lower 30s expected well inland and mid/upper 30s closer to the coast. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... An active period of winter weather looks to be setting up for next week. While there is considerable data spread lending uncertainty to the exact details, what is fairly certain is that an arctic airmass and Pacific jet will combine to provide the dynamics, thermal gradient and moisture needed for periods of potentially hazardous weather. The models do agree on fair weather at this time for Tuesday. Otherwise... Sunday and Monday: Low pressure ejects from the Rockies onto the Plains and tracks quickly eastward across the country. The warm front associated with the system will begin to approach the area from the west by Sunday night. Ahead of the surface front, overrunning precipitation should produce at least some light snow across the area Sunday afternoon and evening. The exact track of the low and associated warm front will then be critical to when and if the precipitation changes over to rain, sleet or even freezing rain Sunday night into Monday. Right now the models suggest the warm front gets to roughly the vicinity of the Mass Pike. However, this is too far out to have any confidence on this fine of detail, so a broad rain or snow approach was used in the forecast. Significant snowfall is most likely across the northern and western interior, even if there is indeed a changeover in those area. As a result, the Hazardous Weather Outlook will include Orange county in a 6 inch snowfall risk. The precipitation may change back to a snow, again depending on track which means the dry slot in this case, at the end of the event. The biggest hazard Monday night however may be the development of black ice. Wednesday: Both the GFS and ECMWF have cyclogenesis somewhere over the Atlantic. The ECMWF has the low about 325 miles southeast of Montauk at 00Z Thursday. The GFS is only 125 miles south of Manhattan at the same time. The models have been consistent the last few days with some kind of development, so it seems there will be a system to at least watch for the middle of next week. The probability for precipitation was capped at 30 percent. Thursday: Arctic air will infiltrate the Tri-State Region. This is very far out, so timing changes (including the potential Wednesday low) cannot be completely ruled out. However, the models have been consistent that Thursday is the day for the frigid airmass to flow in. The atmosphere will not be able to hold much moisture, so with temperatures in the stratus deck progged to run in the -15C to -25C range, flurries or periods of light snow are expected. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... VFR conditions as high pressure builds in from the west through the TAF period. Only exception would be brief MVFR conditions for any snow flurries or isolated snow showers, particularly N/W of city terminals today. Gusty WNW winds into this evening with gusts in the 25-30 kt range, lasting longest for the city terminals. Winds will decrease late tonight, more so outside NYC Metro. NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/www.weather.gov/zny/n90 KJFK TAF Comments: Winds will average around 310 magnetic through this evening, but 20 to 30 degree variability is possible at times. Max wind gusts through 22Z and could peak out between 30-35 kt. KLGA TAF Comments: Winds will average around 310 magnetic through this evening, but 20 to 30 degree variability is possible at times. Max wind gusts through 22Z and could peak out between 30-35 kt. KEWR TAF Comments: Winds will average around 310 magnetic through this evening, but 20 to 30 degree variability is possible at times. Max wind gusts through 22Z and could peak out between 30-35 kt. The afternoon KEWR haze potential forecast is GREEN...which implies slant range visibility 7SM or greater outside of cloud. KTEB TAF Comments: Winds will average around 310 magnetic through this evening, but 20 to 30 degree variability is possible at times. Max wind gusts through 22Z and could peak out around 30 kt at times. KHPN TAF Comments: Max wind gusts expected through 22z and could peak out between 30-35 kt. KISP TAF Comments: Max wind gusts expected through 22Z and could peak out between 30-35 kt. .OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY... .Saturday...Mainly VFR. Again only exception would be brief MVFR for any isolated snow showers or snow flurries. .Saturday night...VFR. .Sunday...MVFR/IFR possible with a chance of light rain/snow. .Sunday night and Monday...MVFR/IFR in snow Sunday night, mixed precipitation near the coast, becoming plain rain along coast Monday. .Monday night...Lingering snow/rain. MVFR/IFR possible. .Tuesday...Mainly VFR. && .MARINE... Opted to issue gale warning for today for the ocean waters, where winds have already been gusting up to 35 kt especially west of Fire Island Inlet, and should continue to do so at least into the morning if not all day. Otherwise, SCA continues on the remaining waters, with winds gusting up to 30 kt, and seas on the eastern Sound reaching 5 ft in downwind locations off the north shore of eastern Long Island. Winds and seas should then gradually subside below SCA criteria, first this evening on the Harbor/western Sound/south shore bays, then overnight on the eastern Sound/bays, and finally on the ocean Sat morning. There is a low chance for SCA conditions to develop Sunday night. Seas on the ocean will build however on Monday as low pressure passes through. Conditions improve on Tuesday with high pressure building in. Low pressure may develop over the Atlantic during the middle of the week, which could bring at least SCA conditions. && .HYDROLOGY... Up to an inch of rain and/or liquid equivalent is possible Sunday through Monday. && .EQUIPMENT... New York City NOAA Weather Radio NWR transmitter KWO-35 is experiencing intermittent outages. Central Park (NYC) observations (METAR) are still unavailable due to an area power outage. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until midnight EST tonight for ANZ335-338- 345. Small Craft Advisory until 6 AM EST Saturday for ANZ330-340. Gale Warning until 6 PM EST this evening for ANZ350-353-355. && $$ SYNOPSIS...JMC/Goodman NEAR TERM...JC/Goodman SHORT TERM...Goodman LONG TERM...JMC AVIATION...JM/DS MARINE...JMC/Goodman HYDROLOGY...JMC/Goodman EQUIPMENT...

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