Area Forecast Discussion
Issued by NWS Upton, NY

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886 FXUS61 KOKX 212038 AFDOKX Area Forecast Discussion National Weather Service New York NY 338 PM EST Tue Feb 21 2017 .SYNOPSIS...
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High pressure drifts offshore tonight, as a weakening cold front moves towards this area. This front then dissipates as it moves into western portions of the area Wednesday, as the region comes under the influence of high pressure centered well off the Carolina coast through Thursday. A spring-like pattern for the end of this week will transition into a more seasonal pattern for the second half of the weekend into the beginning of next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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A deep layered ridge slides offshore this evening, allowing for a northern stream 700-500 hPa shortwave to track across southeastern Canada, as zonal flow sets up over the region. All models show weak warm advection at 850 hPa late tonight, so do bring in slight chance pops (chance far W Orange County) for light rain after midnight. Lows tonight were based on a blend of MAV/MET/ECS guidance and NAM 2-meter temperatures and should be around 10-15 degrees above normal.
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&& .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
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The low level warm advection should come to an end by Wednesday afternoon and a weak northern stream 700-500 hPa shortwave ridge should build over the area, confining any light rain to the morning hours. There does appear to be sufficient consensus on the occurrence of the light rain to raise pops to chance over all but the SW corner of the CWA - where only slight chance pops as the best warm advection should be north of there. As the northern stream shortwave ridging slowly works east, it appears that low-mid level drying should occur overnight, leaving a moist near surface layer underneath. Noting SW-WSW flow aloft, there is the potential for patchy drizzle/fog late Wednesday night as well as some stratus with the second night of onshore flow. Highs Wednesday were based on a blend of MAV/ECS/MET guidance, NAM 2-meter temperatures and a mix down from 975-950 hPa per BUFKIT soundings. Highs should be around 10-15 degrees above normal - with lowest departures over Long Island/S CT and largest departures over NE NJ/Lower Hudson Valley. Lows Wednesday night were based on a blend of MET/ECS/MAV guidance and NAM 2-meter temperatures and should be around 15-20 degrees above normal - and fairly close to normal highs for this time of year.
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&& .LONG TERM /THURSDAY THROUGH MONDAY/...
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Southwesterly flow into California and southerly flow from the Gulf of Mexico per water vapor both indicate a mild pattern setting up until a Pacific trough south of Alaska slowly tracks across the country. Forcing will be limited Thursday and Friday to some weak frontogenesis associated with a warm front Friday. This should be the best chance for measurable rain. Otherwise, patchy drizzle and fog, along with extensive cloud cover, are expected due to the persistent onshore flow. This will limit temperatures both days, especially across Long Island and Connecticut. There is the potential for readings to soar into the 70s west of the Hudson River on Friday if the clouds mix out due to a pure southerly flow as opposed to southeasterly. Showers will then be possible in the warm sector Friday night into Saturday. However, the marine layer may set up over most of the area and keep the region in the fog and drizzle. The Pacific trough finally arrives over the weekend, and the associated cold front will produce a round of rain across the forecast area. The ECMWF remains about 6 hours slower than the GFS, so the probability for this rain was capped at 70 percent and extended from Saturday afternoon into Saturday night. A cooler airmass will build in for Sunday, although it won`t be particularly cold with 850 millibar temperatures around -9C and deep mixing on westerly flow. There is a bit of a break down in model consensus Monday and Tuesday as the GFS continues to produce a weak system on Monday and isentropic lift ahead of a warm from on Tuesday. The ECMWF has nothing on Monday and a little with the warm front on Tuesday. Chances for precipitation were capped at 30 percent. Although the official forecast highs for Monday are generally in the 40s, this incorporates more of a model consensus coupled with climatology. If the potential system were to be forecast explicitly, highs would be in the 30s with mainly snow.
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&& .AVIATION /20Z TUESDAY THROUGH SUNDAY/...
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A weak cold front dissipates as it approaches the region late tonight into Wednesday. VFR is expected through at least 06z. Low chance of MVFR ceilings in light rain...mainly across northern terminals late tonight into early Wednesday morning. VFR likely again later Wednesday area wide. Winds S to SE generally around 10 KT. A few gusts to 15 KT possible interior NJ and NYC terminals this evening. Winds become light and variable tonight and SW 5 to 10 kt with a few isolated gusts Wednesday. 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: No unscheduled amendments expected. KLGA TAF Comments: No unscheduled amendments expected. KEWR TAF Comments: No unscheduled amendments expected. KTEB TAF Comments: No unscheduled amendments expected. KHPN TAF Comments: No unscheduled amendments expected. KISP TAF Comments: No unscheduled amendments expected. .OUTLOOK FOR 21Z WEDNESDAY THROUGH SUNDAY... .Wednesday...VFR. MVFR possible late Wednesday night in stratus and fog. .Thursday-Friday...MVFR, possibly lower, in stratus and fog. .Saturday...MVFR likely with showers. .Sunday...VFR...Gusty NW Winds.
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&& .MARINE...
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A relaxed pressure gradient over the waters around Long Island Tonight through Wednesday night will limit winds to 10 kt or less and seas on the coastal ocean waters to 2 ft or less and seas/waves on the non-ocean waters to 1 ft or less during this time frame. Winds and seas are forecast to remain below Small Craft Advisory levels from Thursday through Friday night. Small Craft Advisory criteria is likely over the weekend associated with the approach and passage of a cold front.
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&& .HYDROLOGY...
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A few hundredths of an inch of precipitation or less is possible through Friday night, with no hydrologic impact expected. Around an inch of rain is possible Saturday and Saturday night. Thereafter, widespread significant precipitation is not expected at this time.
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&& .CLIMATE...
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The following are record maximum minimum temperatures for Wednesday February 22, 2017 along with the forecast minimum temperature. Record Max Minimum Temperature Forecast Minimum Temperature ------------------------------ ---------------------------- Central Park........46 (1996) 42 LaGuardia...........45 (2012) 42 Kennedy.............44 (1981) 41 Islip...............44 (1996) 40 Newark..............46 (1996) 41 Bridgeport..........39 (2002) 38 The following are record maximum minimum temperatures for Thursday February 23, 2017 along with the forecast minimum temperature. Record Max Minimum Temperature Forecast Minimum Temperature ------------------------------ ---------------------------- Central Park........55 (1985) 47 LaGuardia...........54 (1985) 47 Kennedy.............47 (1990) 43 Islip...............46 (1990) 40 Newark..............51 (1985) 46 Bridgeport..........40 (1985) 40
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...Maloit/12 NEAR TERM...Maloit SHORT TERM...Maloit LONG TERM...12 AVIATION...IRD MARINE...Maloit/12 HYDROLOGY...Maloit/12 CLIMATE...JE

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