Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 090932 AFDOKX Area Forecast Discussion National Weather Service New York NY 432 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/... Brisk NW flow will continue today, gusting to 30-40 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 well 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 scattered flurries or snow showers are expected. High temps should be in the 30s, with wind chills in the 20s. && .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 /09Z FRIDAY THROUGH TUESDAY/... VFR through the TAF period. High pressure builds through Friday. NW winds continue through tonight. Gusty winds will continue tonight and may relax somewhat overnight. Gusts could become more occasional overnight, mainly in the outlying terminals, while there may not be any gusts for other outlying terminals (specifically KISP, KSWF and KGON). Winds and gusts will increase after sunrise Friday with gusts 25 to 30 kt late morning into the afternoon. .OUTLOOK FOR 06Z SATURDAY THROUGH TUESDAY... .Friday afternoon...Flurries or snow showers possible mainly NW of NYC metro. NW winds G20-30KT. .Saturday...VFR. .Sunday...Mainly VFR. Chance of light snow late. .Sunday night and Monday...MVFR or IFR in snow Sunday night, changing to mixed precipitation near the coast on Monday. .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...Goodman SHORT TERM...Goodman LONG TERM...JMC AVIATION...JM MARINE...JMC/Goodman HYDROLOGY...JMC/Goodman EQUIPMENT...Goodman/JM is the U.S. government's official web portal to all federal, state and local government web resources and services.