Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 140933 CCA AFDOKX Area Forecast Discussion...CORRECTED National Weather Service New York NY 433 AM EST Wed Feb 14 2018 .SYNOPSIS... A weak low passes farther out into the Atlantic southeast of the region today. A warm front moves across tonight into Thursday following by an approaching cold front. This cold front will move across the area on Friday. High pressure then builds in through Saturday, with a developing coastal storm possibly impacting the area Saturday night into Sunday morning. High pressure returns behind this system for Sunday night. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Weak wave of low pressure passes southeast of Long Island farther into the Atlantic today. Zonal flow aloft with exiting jet streak today. Colder cloud top temperatures with batch of precipitation moving into the region. Expecting this precipitation to be light and will be a wintry mix and just plain light rain and light sleet for much of the coast. A low level warm nose above freezing moves in between 10-12Z, enough for potential freezing drizzle or light freezing rain. This is possible for interior parts of the region, namely those locations that are still at or below freezing. Special weather statement addresses the above concern as well as potential black ice formation. By 13Z, expecting all precipitation to be tapering off with drying and a decrease in clouds. This will be with the exiting jet streak. In the mid levels, there will be nearly steady height tendency. At the surface, high pressure will briefly build in. Looking at a larger perspective, the area will be on the northwest side of a large broad area of high pressure based in the Atlantic. This will give the area SW-WSW flow and an approaching low pressure system going into the Great Lakes will be increasing the pressure gradient. The SW-WSW flow will become gusty and this will promote greater vertical mixing and low level warm air advection. Took the warmer MAVs for temperatures today, which are forecast to be almost 10 degrees above normal with some more sunshine expected by this afternoon.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... There will be another wave of low pressure for tonight and this will be the one from the Great Lakes. It will have an associated warm front that will be moving across going into early Thursday. The region will be getting into the left front quad region of an upper level jet. There will be a high likelihood of rain tonight into Thursday morning. Airmass behind the warm front will be warmer. Model 850mb temperatures will be trending a few degrees warmer compared to the previous day. Same SW flow will be expected during the day at a less magnitude, but vertical daytime mixing will result in surface temperatures warmer than the previous day with highs approaching 60 and getting into the low to mid 60s for some areas, which will be around 20 degrees above normal. Clouds will be on the increase though as a cold front approaches the region. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... The upper pattern across North America at the start of the long term period will consist of a strong vortex just north of Hudson Bay and strong upper level high pressure over the Gulf of Mexico resulting in quasi-zonal flow between these features east of the Rockies. This general pattern will hold into early next week although there will be a gradual amplification of the longwave pattern as the Canadian vortex and SE ridge shift eastward. This will raise heights along the east coast during the first half of next week and deepen western US trough. A progressive pattern will result from this quasi-zonal flow with perturbations moving through it from time to time. The first will come Thu Night/Fri as shortwave trough and associated cold front approach and move through the area. Thermal profiles support a liquid event for the entire area with less than 1/2" of total rainfall. Dry weather is then expected as high pressure builds across the area Fri night into Sat. Solutions begin to diverge thereafter, although there is a signal amongst most of the deterministic guidance as well as several members of the GEFS and ECENS of a developing coastal storm due to northern and southern stream phasing energy. The GFS keeps is not phasing the 2 streams together, and thus is resulting in a track well south of the area. However, given the signal from the EC, CMC and members of the GEFS/ECENS, feel it`s prudent to include chc pops at the current time. These phasing systems are always tough and the probability of greater than .5" of liquid equivalent QPF is less than 30% in both the GEFS and ECENS so will keep the mention for a potential heavy snow event out of the HWO for now, although it is certainly a possibility. Any impacts from this system move out quickly Sun morning with another area of high pres building in into Mon. Another frontal system will approach late Mon, keeping unsettled weather in play into the middle of next week. && .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... A prolonged period of SW flow can be expected until a cold front passes through on Friday. Patchy light rain and/or freezing rain/drizzle possible through 12Z. Any freezing precipitation will be confined to the Lower Hudson Valley terminals. Largely going with a VFR forecast through this evening as a warm front approaches from the southwest. An occasional MVFR ceiling is not out of the question at 1500 to 2500 ft. MVFR/IFR conditions will then develop after 06Z Thursday with onset of rain. SW winds will gradually increase today to around 10 kt with possible gusts this afternoon of 15 to 20 kt. Winds will diminish to 5 kt or less tonight. ...NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: KJFK TAF Comments: Occasional MVFR ceiling possible through around 18Z. Gusts up to 20 kt possible. The afternoon KJFK haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KLGA TAF Comments: Occasional MVFR ceiling possible through around 18Z. Gusts up to 20 kt possible. The afternoon KLGA haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KEWR TAF Comments: Occasional MVFR ceiling possible through around 18Z. Gusts up to 20 kt possible. The afternoon KEWR haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KTEB TAF Comments: Occasional MVFR ceiling possible through around 18Z. Gusts up to 20 kt possible. KHPN TAF Comments: Occasional MVFR ceiling possible through around 18Z. Gusts up to 20 kt possible. KISP TAF Comments: Occasional MVFR ceiling possible through around 20Z. Gusts up to 20 kt possible. .OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY... .Thursday...IFR/MVFR with rain ending early. Chance VFR in the afternoon. .Thursday Night into Friday...Rain likely with MVFR or lower possible. NW winds G25KT Friday afternoon/evening. .Saturday...VFR. .Saturday Night...MVFR or lower with a chance of snow. .Sunday...Improving to VFR. && .MARINE... A prolonged period of SW flow will prevail through Friday morning before a cold front passes through by early afternoon. Seas on the ocean will be gradually build during this time and will likely exceed 5 ft late Thursday night and continue to build into the day on Friday. NW gusts 25-30kt are likely across all waters Friday afternoon into Friday night behind the cold front. High pressure then follows for Saturday with diminishing winds and seas. There is some uncertainty Saturday night into Sunday as to how close to the waters deepening low pressure gets while passing to the south. For the time, took a middle road approach here and kept winds below SCA criteria with seas building to around 5 ft on Sunday. && .HYDROLOGY... No hydrologic threats are anticipated through the weekend. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...JM NEAR TERM...JM SHORT TERM...JM LONG TERM...24 AVIATION...DW MARINE...DW HYDROLOGY...JM EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.