Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 012018 AFDOKX Area Forecast Discussion National Weather Service New York NY 318 PM EST Thu Dec 1 2016 .SYNOPSIS...
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Low pressure moves into the Canadian Maritimes tonight into Friday. High pressure will build in over the weekend, then break down as a series of frontal systems impact the area next week.
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&& .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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Closed upper level low and trough remain located to the north tonight. Surface low pressure along the Canadian Maritimes slowly drifts northeastward, maintaining it`s strength around 990 hpa. Persistent westerly flow due to a fairly tight pressure gradient continues, although gusts should become less frequent as boundary layer cools with the loss of daytime heating. Instability clouds should break and scatter as the evening progresses, leaving partly cloudy to mostly clear skies. Cold air advection ends, and temperatures should fall into the 30s, except bottom out around 40 in NYC.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
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Upper low drifts east, with shortwave and associated pva pivoting southeastward across across New England Friday night. At the surface, coastal low drifts east off the eastern Canadian coast as inland low weakens further. A trough begins to track east, well up in New England Friday night. Our area remains well mixed in persistent westerly flow as the pressure gradient between this slow moving low to the northeast and high pressure well to the west remains fairly tight. Daytime gusts will occur once again, likely becoming less frequent at night. Temperatures remains near normal, with daytime highs ranging from the middle 40s to around 50, and lows in the 30s. Partly to mostly sunny skies Friday will give way to a few more strato-cu clouds at night, associated with upper trough.
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&& .LONG TERM /SATURDAY THROUGH THURSDAY/...
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The models were in fairly good agreement for this weekend, then there is a considerably high amount of spread in the data for the remainder of the forecast period. A 1030 high over the plains drifts towards the forecast area over the weekend. This keeps a breezy northwest flow locked in. With regard to precipitation, the area should be surrounded by lake effect to the north and west, and ocean effect to the south and east. As a result, the forecast has been kept dry. The Superblend was used for temperatures. The pattern for next week is not conducive to a solely blended approach, as this would lead to precipitation chances every day and smooth out the temperatures extremes. To complicate matters, the 12Z ECMWF was not available for the forecast. The 12Z GFS was therefore closely followed, but not blindly, as the general pattern was supported by the 00Z ECMWF and 06Z GFS. The first system is low pressure tracking northeastward from the southeastern United States. The timing on this is Tuesday and Tuesday night. There remain questions as to whether the low actually reaches the area or stays to the south, or if the low tracks to the east and warm slots the area. The probability of precipitation was therefore limited to 40 percent. An arctic front and possible associated low then come through by the end of the week. Again, the 12Z GFS was used which has a timing of Wednesday night into Thursday. Both systems will bring some chance for wintry precipitation, with the arctic front perhaps presenting a flash freeze threat.
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&& .AVIATION /20Z THURSDAY THROUGH TUESDAY/... Westerly flow behind a departing area of low pressure will continue into the day on Friday. VFR through the TAF period. Strato-cu resulting in broken ceilings at around 4500 ft this afternoon will dissipate this evening. Main impact through the period will be gusty west winds. While the prevailing wind direction is expected to remain to the left of 310 magnetic, gusts will range from 20-25 kt, with occasional gusts in the 25-30 kt range at the city terminals. Winds and gusts will diminish after 00Z at outlying terminals, but will linger through the evening push at the NYC/NJ metro airports. Gusts then return mid-late morning on Friday at around 20 kt. 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: A few gusts to around 30 kt are possible this afternoon in westerly flow. KLGA TAF Comments: A few gusts to around 30 kt are possible this afternoon in westerly flow. KEWR TAF Comments: A few gusts to around 30 kt are possible this afternoon in westerly flow. KTEB TAF Comments: A few gusts to 25-30 kt are possible this afternoon in westerly flow. KHPN TAF Comments: A few gusts to 25-30 kt are possible this afternoon in westerly flow. KISP TAF Comments: A few gusts to 25-30 kt are possible this afternoon in westerly flow. .OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... .Friday...VFR. West gusts 20-25 KT. .Saturday...VFR. NW gusts around 20 KT. .Sunday...VFR. .Monday-Tuesday...VFR...possibly lower at times depending on the track of low pressure to the south. && .MARINE...
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The waters remain between deep low pressure near the Canadian Maritimes and high pressure well to the west through Friday. Gusty westerly winds continue tonight, with SCA remaining in effect for all waters. These westerly winds continue Friday, although they are expected to diminish just below SCA thresholds, or 25 kts, for the non ocean waters. As such, will not extend the SCA beyond 6 am at this time, but will for the ocean waters as seas remain elevated to around 5 ft. However, any slight decrease in winds looks to be short lived as winds begin to turn somewhat to the west/nw and increase just a bit late Friday and Friday night. As such, a new SCA for the non ocean waters may be needed. Winds and seas will subside gradually over the weekend. Small craft criteria is possible, especially Saturday on the ocean. For next week, a series of frontal systems will produce hazardous conditions at times.
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&& .HYDROLOGY...
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After a dry weekend, periods of precipitation will be possible next week as a series of frontal systems impact the area.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 AM EST Friday for ANZ330-335-338- 340-345. Small Craft Advisory until 6 AM EST Saturday for ANZ350-353- 355.
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&& $$ SYNOPSIS...JMC/PW NEAR TERM...PW SHORT TERM...PW LONG TERM...JMC AVIATION...FEB MARINE...JMC/PW HYDROLOGY...JMC

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