Area Forecast Discussion
Issued by NWS Upton, NY

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022 FXUS61 KOKX 221628 AFDOKX Area Forecast Discussion National Weather Service New York NY 1128 AM EST Thu Feb 22 2018 .SYNOPSIS... High pressure builds in from the north today, however a weak low pressure trough will be passing to the south at the same time. High pressure then weakens on Friday as it moves offshore and another weak area of low pressure shifts through near us. A cold front moves through Friday night as high pressure builds to the north. A warm front approaches Sunday, and a cold front passes late Sunday. High pressure builds early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Main update was to delay the sleet another hour or two. Also have removed a lot of the freezing rain from the forecast. While the threat has diminished, can not rule brief period of some freezing rain. Latest observations and hi- res forecast models hinting that the primary p-type will be rain or sleet, with some snow possible as the precipitation ends. Otherwise, high pressure center shifts through southern Quebec today with ridging into the tri-state area today. At the same time, a weak trough of low pressure will be shifting east along a stalled boundary to our south. Additionally, 850-700 mb shortwave energy will provide some lift, and with RH values in this layer remaining high on a SW flow, it`ll be a cloudy day with some light to moderate PCPN. Higher overall PoPs will be this afternoon, coinciding with the deepest moisture and lift. PCPN types across the area will be tricky across a good portion of the area. NAM/RAP/HRRR/RGEM continue to be on the warmer side regarding temperatures in a warm-nose aloft at 800-700 mb while the global models are colder. The strength of this warm nose in combination of lower-level sub-freezing temperatures, including some freezing surface temps this afternoon, will have implications on PCPN types. Prefer warmer temps aloft with the SW flow, and will lean towards NAM in this regard, but it might be too warm aloft. High pressure to the north and NNE surface winds will help low-level cold air drainage/damming across CT and the Lower Hudson valley. Will therefore lean towards NAM for lower-level temps and use its 2-meter temps for the surface at it tends to perform better with thermal profiles in this type of setup, especially within 24 hours. No winter weather headlines will be issued at this time. Thermal profiles support sleet primarily north of NYC. Sleet accumulations expected to be limited to under an inch. Will address the low probability of freezing rain and sleet potential with an SPS across the northern zones. Rain is otherwise expected elsewhere, but even a chance of sleet exists as far south as the city, Long Island and NE NJ by late. Expect temperatures to fall into the 30s everywhere by early afternoon. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Models from 24 hours ago have trended drier along with stronger ridging into the region tonight. PCPN ends early this evening with dry weather most of the night. Another wave of low pressure passes nearby. PCPN then spreads east to west Friday morning, with all areas seeing PCPN during the afternoon. Thermal profiles support rain for the most part, however western Orange County can pick up a couple hours of freezing rain. Right now do not have the confidence and coverage to go with an advisory, and will let subsequent shifts assess trends and issue any as needed. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Aloft, fast westerly flow, with embedded weak shortwaves ride over the top of the southern ridge initially. Downstream trough out west tracks across the mid section of the country Saturday moving southwest to northeast across the Great Lakes region. Ahead of this, heights rise along the eastern seaboard. Trough passes early next week with ridging Tuesday and Wednesday ahead of next trough out west. At the surface, models agree in a cold front sagging just south Friday night into Saturday as high pressure builds to the north. This will result in a brief period of dry weather later Friday night into Saturday. Then the front begins to move back to the north as a warm front Saturday night into Sunday. It appears that a triple point low tracks across the area, with occluded front to the north extending from the parent low that tracks to the north of the Great Lakes region. The cold front passes Sunday night. High pressure then builds Monday through Wednesday, with perhaps a weak trough passing late Tuesday. Any lingering rain Friday evening ends briefly, then next round of rain moves back in late Saturday from southwest to northeast. The bulk of the rain occurs Saturday night through Sunday morning. Rain tapers off later Sunday behind the triple point low and front. Warm enough for plain rain everywhere. Dry weather is expected thereafter. Temperatures remain above normal, but not as warm as the past couple of days. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... A weak wave of low pressure tracks south of the terminals today along a stalled cold front. VFR conditions lower to MVFR around midday, with some uncertainty as to how quickly ceilings will lower, which may be later than forecast. MVFR ceilings this afternoon into tonight with a chance of IFR mainly east and north of the NYC metro terminals. Light rain is expected to transition to rain and sleet this afternoon from the north and west to the south, with more uncertainty as to how much sleet will mix with the rain toward the coast, the NYC metro terminals, before the precipitation ends early this evening. The chances of freezing rain has diminished. NE wind 10 to 15 kt with occasional gusts up to 20 kt along the coast. ...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: There is a slight chance of ice pellets/sleet late this afternoon. Gusts will be more intermittent this morning,and likely end this afternoon. Timing of lowering flight categories to MVFR may be several hours later. KLGA TAF Comments: There is a slight chance of ice pellets/sleet late this afternoon. There may be occasional gusts up to 20 kt mainly this morning, with gusts ending this afternoon. Timing of lowering flight categories to MVFR may be several hours later. KEWR TAF Comments: There is a slight chance of ice pellets/sleet late this afternoon. There may be occasional gusts up to 20 kt mainly this morning, with gusts ending this afternoon. Timing of lowering flight categories to MVFR may be several hours later. KTEB TAF Comments: There is a slight chance of ice pellets/sleet mid afternoon to late afternoon. Timing of lowering flight categories to MVFR may be several hours later. KHPN TAF Comments: There is a slight chance of ice pellets/sleet this afternoon, with some light snow possible late this afternoon into early this evening before the precipitation ends. The chance of freezing rain has diminished and there may be a brief period later this afternoon. Timing of lowering flight categories to MVFR may be several hours later, late this afternoon. KISP TAF Comments: There is a slight chance of ice pellets/sleet late this afternoon into early this evening. Timing of lowering flight categories to MVFR may be several hours later this afternoon. .OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY... .Fri...MVFR/IFR in rain with a wintry mix at SWF. .Sat...CHC MVFR and rain. .Sun...MVFR/IFR in rain. S winds G20 KT. .Mon...VFR. && .MARINE... SCA is in effect for the ocean waters this afternoon and tonight as easterly winds gust around 25 kt while building seas up to 5-6 feet. May need to extend it into a part of Friday morning. Rest of the water should remain below advisory criteria through Friday. A cold front passes across the waters Friday night, then moves back as a warm front Sat night into Sunday. High pressure builds briefly to the north during this time, but departs well to the east by Sunday. Low pressure passes Sunday, with a cold front moving through Sunday evening. High pressure builds behind on Monday. Tranquil winds and seas are forecast Friday night and Saturday. Easterly winds increase Saturday night ahead of the warm front and low pressure center. A period of SCA winds and rough ocean seas are possible during this time. The winds shift around to the west behind the front Sunday night and Monday. Rough ocean seas will gradually subside. && .HYDROLOGY... Liquid equivalent precipitation amounts today are expected to range from a quarter to half inch, with the same amounts expected for Friday as well. Hydrologic impacts are not expected. No hydrologic impacts are expected either this weekend, with rainfall amounts generally ranging from a half an inch to an inch. && .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...Small Craft Advisory until 6 AM EST Friday for ANZ350-353-355. && $$ SYNOPSIS...JC/PW NEAR TERM...BC/JC SHORT TERM...JC LONG TERM...PW AVIATION...19 MARINE...BC/JC/PW HYDROLOGY...JC/PW EQUIPMENT...

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