Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 282105 AFDOKX Area Forecast Discussion National Weather Service New York NY 405 PM EST Tue Feb 28 2017 .SYNOPSIS... A warm front approaches tonight and moves north of the region Wednesday morning. Low pressure moves from the central United States and into the Great Lakes region Wednesday into New England Wednesday night with a strong cold front approaching Wednesday, and moving through Wednesday night. Strengthening low pressure in the Canadian Maritimes Thursday will be followed by an Alberta Clipper moving across the local region Friday, moving offshore Friday night. High pressure builds to the west, then moves over the region Saturday night, and off the southeastern coast Sunday. Meanwhile for Sunday and into early next week, low pressure will approach the region from southeastern Canada. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Weak ridging will remain in place tonight as a full latitude trough moves through the central United States. Meanwhile surface low pressure also moves through the plain states. An associated warm front will approach as a weak vort max moves through the ridge. The combination of weak lift with the front and vort max will produce light rain with the best chances south of Long Island. Stratus remains in place along the coast and is expected to expand this evening. In addition fog is expected to develop with visibilities lowering. At this time not expecting the visibilities to lower less than one statue mile. Mild air will remain in place and record low maxima may be set Wednesday morning. See the climate section for details. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... The warm front moves through in the morning with the area becoming warm sectored. Fog and stratus improves with the passage of the front. Weak isentropic lift will remain with increasing low level moisture. So will keep a chance of showers across the region. Although there is a possibility of a break in the rainfall. Even though the area will be warm sectored and weak warm advection continues, lowered the high temperatures with cloud cover and ongoing rain. Records are still possible at the climate stations. See the climate section for details. The large scale upper trough moves slowly east Wednesday into Wednesday night with a rather strong shortwave and vort max moving through the northern portion of the trough. Meanwhile, a deepening low moves into the Great Lakes. Instability will be increasing through the day, especially in the afternoon and early evening. Also CAPE increases to 500 to 700 J/KG. Best instability will be from southwestern Connecticut to western Long Island and portions west. Farther to the east instability with be more limited with a marine influence. A strong 500-300 MB jet of 100 to 130 KT will move east across the area Wednesday night, This will be enhancing lift across the area. There is some uncertainty regarding severe weather potential and will depend on the degree on instability. Main threat is strong gusty winds. && .LONG TERM /THURSDAY THROUGH TUESDAY/... A much colder airmass expected Thursday and Thursday night and prevailing through Saturday night. Colder than normal temperatures can be expected with cold air advection from a gusty NW flow Thursday into Thursday evening. An Alberta clipper will be moving through the area on Friday, providing a chance of light snow across the region. Despite the highs being in the upper 30s to near 40 for locations towards the coast, the falling snow aloft will cool the column down to below freezing after a short time. Moisture looks limited with this clipper, with liquid equivalent amounts mostly less than a quarter inch and with temperatures being above freezing initially, not much in accumulation is expected at this time. High pressure builds Friday night and moves off the coast to our south on Sunday. Precipitation expected on Sunday night into Monday as a boundary moves through the area. A front approaches on Tuesday providing an chance of showers across the region. Temperatures will be below normal on Saturday, then bounce back to normal levels on Sunday before climbing to above normal for the start of the week. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... Extensive stratus field beginning to develop offshore has already moved into JFK, ISP, BDR and GON. Expect the stratus to continue to expand north and westward in light south-southeasterly flow. As such, have amended all TAF sites for an earlier start to deteriorating conditions, with IFR expected as early as 22Z now. Conditions will fall to LIFR overnight. Winds will remain out of the south-southeast at generally 10 kt or less. The exception will be at LGA where a light sound breeze will keep winds from the northeast until this evening. Overnight, winds will shift to a more southerly direction. A strong SW low-level jet approaches late tonight with low-level wind shear likely at the coastal terminals with 40-50KT winds at 2000 ft. 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: Confidence increasing for conditions to deteriorate faster than previously forecast. Refer to latest amendments. KLGA TAF Comments: Confidence increasing for conditions to deteriorate faster than previously forecast. Refer to latest amendments. KEWR TAF Comments: Timing of IFR conditions may be off +/- 2 hrs. KTEB TAF Comments: Timing of IFR conditions may be off +/- 2 hrs. KHPN TAF Comments: Confidence increasing for conditions to deteriorate faster than previously forecast. Refer to latest amendments. KISP TAF Comments: Confidence increasing for conditions to deteriorate faster than previously forecast. Refer to latest amendments. .OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY... .Wednesday afternoon-Wednesday night...Showers and a chance of thunderstorms. MVFR or lower possible. SW winds G20-30KT, higher in thunderstorms. Winds become westerly late Wednesday night. .Thursday...VFR. W-NW winds G25-35KT. .Friday...MVFR/IFR possible with a chance of light snow. NW winds G20-25KT. .Saturday...VFR. NW G20-25KT. .Sunday...VFR. Chance of rain. SW winds G20KT. && .MARINE... High pressure was to the east of the forecast waters, off the northeast coast, with deepening low pressure moving through the central United States. A rather weak pressure gradient force was across the waters with a light southerly flow. Winds and seas are expected to remain below small craft levels through tonight across the forecast waters. As a warm front moves through the waters, and deepening low pressure moves into the Great Lakes region, a south to southwest flow will increase during Wednesday. With the persistent southerly flow ocean seas will build to small craft levels early Wednesday. Then wind gusts are expected to increase and be around minimal small craft levels across all the forecast waters later in the day. With warmer air coming up over the cooler waters mixing will be limited and gusts may not reach small craft levels. A warm front will be nearing the waters tonight, and then move through Wednesday morning. Fog is expected to develop with visibilities lowering through tonight. There is a possibility of visibilities lowering to around 1 nautical mile. With the approach of a cold front during Wednesday, and moving through late Wednesday night, thunderstorms will become likely by the afternoon. Some of these storms may produce very strong wind gusts into the evening hours. With the deepening low passing to the north Wednesday night strong winds may still be around small craft levels through the night. Gales possible across the area waters on Thursday as gusty westerly winds of 30 to 40 knots develop as a result of cold air advection behind a frontal system. Seas are forecast to increase to 8 to 11 feet on Thursday. A gale watch is in effect Thursday through Thursday evening. Winds will decrease Thursday night initially to SCA levels for the ocean and then below that by overnight Thursday night. Non-ocean waters will have sub SCA winds Thursday night. Another round of gales possible for the ocean Friday through Saturday with SCA winds for non-ocean waters. Winds then subside below SCA levels Saturday night and into Sunday. && .HYDROLOGY... Rainfall from tonight through Wednesday night is expected to total around 3/4 of inch, with locally higher amounts possible. While the possibility is low, stronger convection could cause isolated minor flooding of poor drainage/urban areas. No hydrologic impacts expected Thursday through the beginning of the week. Melting of the snow pack in Vermont and Massachusetts has caused significant rises along the Connecticut River. && .CLIMATE... Record highs for Wednesday March 1 Location.......Record High/Year Set.....Forecast High Newark..................75/1972...............71 Bridgeport..............59/1972...............63 Central Park............73/1972...............67 LaGuardia...............68/1972...............71 J F Kennedy.............58/2004*..............64 Islip...................60/2004...............65 * = and in previous years Record high minimum temperatures for Wednesday March 1 Location....Record High Min/Year Set.....Lowest Temperature during 24 hour day Newark..................43/1976...............51 Bridgeport..............41/1976...............46 Central Park............45/2004...............54 LaGuardia...............44/2004...............53 J F Kennedy.............42/1974*..............49 Islip...................39/2016...............47 * = and in previous years && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Gale Watch from Thursday morning through Thursday afternoon for ANZ338-345-350-353-355. Small Craft Advisory from 6 AM Wednesday to 6 AM EST Thursday for ANZ330-335-338-340-345-350-353-355. && $$ AVIATION...MD

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