Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 072106 AFDOKX Area Forecast Discussion National Weather Service New York NY 406 PM EST Wed Dec 7 2016 .SYNOPSIS... Weak high pressure builds in tonight...followed by a series of cold fronts cross the area Thursday through Saturday. High pressure follows for Saturday night into Sunday. This moves offshore and gives way to low pressure impacting the Tri-State from Sunday night into Monday night. High pressure returns Tuesday into Wednesday next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Weak northern stream ridging exits to the east this evening with SW flow aloft in its wake tonight. With no shortwaves of note embedded in the flow, it should be dry. Cloud cover should scatter out fairly quickly after midnight. For lows tonight a blend of MAV/MET/ECS guidance and NAM 2-meter temperatures was used, with values a few degrees above normal. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... A northern stream trough builds into the area Thursday and Thursday night, with multiple shortwaves passing over the area as the push around the base of the trough. The first shortwave passes mainly to the north on Thursday and the second on Thursday night. The passage of each shortwave will usher in a shot of progressively colder air. Dry low then mid levels should keep all areas dry through Thursday evening. It appears that there should be sufficient moistening of the low-mid levels by late Thursday night to warrant slight chance of snow showers over the NW 1/3 of the CWA with flurries possible elsewhere in response to the second shortwave. Helping to usher in the cold air will be gusty w-nw winds increasing to 20-30 mph Thursday night - with wind chills mainly in the teens to lower 20s just before sunrise Friday morning. Highs Thursday were based on a blend of MAV/ECS/MET guidance, NAM 2-meter temperatures and a mix down from 925-850 hPa per BUFKIT soundings. Highs should be near normal - with some falling temperatures by mid-late afternoon - especially over western zones. For lows Thursday night, a blend of MAV/MET guidance and NAM 2-meter temperatures was used, with readings around 5 degrees below normal. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Overall a colder weather pattern is shaping up across the region for the long term as conveyed by the upper level jet stream. For most of the time, this jet will be situated south of the region. In the mid levels, a fast quasi-zonal flow Friday through the weekend will become more amplified next week. A small less amplified shortwave moves across Saturday with a stronger one moving across Monday through Monday night. Forecast ends with large amplified trough or cutoff upper level low in Southeast Canada to the Northeast U.S. At the surface, a series of cold fronts move across Friday night through Saturday. High pressure builds Saturday night through early Sunday with a low pressure area then traveling towards the region Sunday night through Monday as the high slides well offshore. Uncertainty on exact position of surface low. For Monday night through mid next week, high pressure returns, building in from the west. Again, uncertainty here with position of high pressure and whether it moves closer to region or stays farther west of the area. In terms of weather, much colder air is expected Friday through Saturday night. Temperatures do not get that much warmer for next week, although Monday, with the development of return southerly flow, temperatures are expected to be well into the 40s for a majority of the region. Otherwise, looking at temperatures during the day mainly 5-10 degrees below normal. In terms of precipitation, snow showers are possible Friday and Saturday with a more widespread precip event expected Sunday afternoon through Monday evening, mainly stratiform. Uncertainty with position of parent low with large differences in terms of precip. For example, latest ECMWF, 12Z Wednesday, shows low well to the west, keeping mainly a rain event, while other models show more of a snow potential inland. All generally show more rain at the coast. Too early to tell with exact rainfall amounts. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... High pressure slowly builds through Thursday. Improvements to VFR will continue through this evening with VFR forecast through the rest of the TAF period. WNW-NW winds, 5-10 kt into this evening. Winds outside the city terminals become light and variable overnight with NW flow under 10 kt continuing at city terminals. Winds back to the W Thursday and become gusty in the afternoon. ...NY Metro Enhanced Aviation Weather Support... Detailed information, including hourly TAF wind component forecasts, can be found at: http:/ KJFK TAF Comments: Brief MVFR may still occur through 23z, but expecting VFR to prevail. Wind direction may average around 310 magnetic this evening. KLGA TAF Comments: Brief MVFR may still occur through 23z, but expecting VFR to prevail. Wind direction may average around 310magnetic this evening. KEWR TAF Comments: Brief MVFR may still occur through 23z, but expecting VFR to prevail. Wind direction may average around 310magnetic this evening. KTEB TAF Comments: Brief MVFR may still occur through 23z, but expecting VFR to prevail. KHPN TAF Comments: Improvement to VFR could be off +/- 1-2 hours from forecast. KISP TAF Comments: Improvement to VFR could be off +/- 1-2 hours from forecast. .OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... .Thursday-Thursday Night...VFR with W-NW G20-25KT. Flurries possible Thurs night. .Friday...VFR with NW gusts 25-30KT, diminishing to around 20KT at night. .Saturday...VFR. .Sunday...Mainly VFR, slight chance of -SN in MVFR inland. .Monday...MVFR or lower possible in chance rain/snow mix inland and chance of rain near coast. && .MARINE... A relaxed pressure gradient will keep winds to 10 kt or less through Thursday morning. However, a persistent ESE-SE swell will keep seas in the coastal ocean waters at SCA levels through around midnight, and possibly a tad longer. As a result, have extended the SCA for hazardous seas on the coastal ocean waters through 05Z tonight. The pressure gradient tightens sharply Thursday afternoon over the and remains fairly tight over all waters Thursday night. As a result expect gusts to 25-30kt on the coastal ocean waters Thursday afternoon and on all waters Thursday night. Active period on the waters with at least SCA conditions Friday through Saturday. Gales will be possible Friday through Friday night for all waters. Sub SCA conditions mostly Saturday night through Sunday with high pressure more in control. SCA conditions resume Sunday night and continue into early next week, mainly on the ocean. && .HYDROLOGY... It should be dry through Thursday evening, then mainly dry late Thursday night through Sunday. There is a chance of a widespread 1/2 inch or more of precipitation from Sunday night through Monday. && .EQUIPMENT... The New York City transmitter, KWO35, is off the air. Time for a return to service is unknown. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory for hazardous seas until midnight EST tonight for ANZ350-353-355. && $$ SYNOPSIS...Maloit/JM NEAR TERM...Maloit SHORT TERM...Maloit LONG TERM...JM AVIATION...DS MARINE...Maloit/JM HYDROLOGY...Maloit/JM EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.