Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KOKX 161732 AFDOKX Area Forecast Discussion National Weather Service New York NY 1232 PM EST Thu Nov 16 2017 .SYNOPSIS... A weak wave of low pressure moves through the area today, followed by a cold front tonight. High pressure briefly builds through late week before another strong low pressure system impacts the area this weekend. High pressure once again builds to the south for early week, followed by a cold front by mid week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Latest update accounted for breaks in the sky cover across Northern New Jersey into Nassau County. Any showers over the Twin Forks of Long Island and New London County in Connecticut will be moving out within the next hour or so. Drier air will be advecting in this afternoon ahead of a cold front. Have adjusted temperatures up a degree or two with this update to account for clearing, however temperatures are not expected to rise much this afternoon. It is possible that a brief shower or two will accompany the frontal passage this afternoon as low-level instability increases. Both the HRRR and the NAM Nest show the possibility of showers developing across the Lower Hudson Valley and northern NJ in the 20-21Z timeframe. Mainly SW winds expected through early this afternoon before veering to the W late this afternoon as the cold front moves through. Gusts 20-25 kt this afternoon, increasing a few knots into tonight as the winds shift more northwesterly. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Despite clearing skies and the advection of a cooler continental polar air mass, winds will remain strong through much of the night which will likely hinder temperatures from falling too far below normal. Should winds subside sooner than forecast, particularly across the lower Hudson Valley, seasonably cool temperatures may be possible overnight. The pressure gradient will remain tight through much of the day as the low departs into eastern Canada and high pressure builds to the west. Temperatures will be close to normal to a few degrees below, with dry conditions and mostly sunny skies as dry air advects southeastward. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... A progressive upper flow will continue into next week. That being the case, there will be multiple interactions with short waves between the polar branches for brief amplification. The first being with jet energy interaction between the southern and northern branches Saturday night into Sunday across the Great Lakes region. This results in the formation of a negatively tilted upper trough/closed low lifting across eastern Canada Sunday into Monday. At the surface, a strong cold front works through the region Sunday morning. Preference continues to be toward the slightly slower ECMWF and GGEM, with the GFS having trended in that direction over the last couple of day. Both pre- and post- frontal winds could gusts up to 40 mph Saturday afternoon through Sunday. While there will be decent warm advection ahead of the system Saturday, dry low-levels will likely limit coverage of any precipitation. Best lift and heaviest rainfall likely comes overnight Saturday along and ahead of the cold front with the potential for up to half an inch. There is some weak elevated instability, so an isolated rumble of thunder is possible. Higher rainfall amounts are possible should the system close off sooner. Deepening low pressure tracking across eastern Canada Sunday into Monday and high pressure building to the southwest will result in a prolonged period of gusty west winds. Another fast moving frontal system approaches on Tuesday and passes through on Wednesday. Latest ECMWF is more amplified and somewhat slower than the GFS. GGEM is even slower. Model consensus was followed at this juncture in time. Temperatures will fluctuate through the period with multiple frontal boundaries in the fast flow. It will be above normal Saturday into Saturday night, then trending down Sunday into Monday behind the departing storm over eastern Canada. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... A cold front crosses the terminals today with an area of low pressure intensifying as it tracks up the New England Coast. High pressure builds to the west tonight into Friday. VFR forecast through the TAF period. A few scattered showers are possible this afternoon as the cold front moves across. Mention of the showers is currently not in the TAF, but they should quickly move through 18-19z across the Lower Hudson Valley, and 19-21z across NYC, Long Island, and southern Connecticut. Winds will continue veering to the W and then WNW this afternoon and evening. Gusts 20-25 KT are expected this afternoon increasing to 25-30 KT this evening and tonight. Occasional peak gusts to 35 kt are possible this evening. WNW winds continue on Friday with gusts continuing. 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: Wind direction likely to stay left of 310 magnetic through this evening. Timing of stronger gusts may be off by a few hours. A brief shower is possible 19-21z. KLGA TAF Comments: Wind direction likely to stay left of 310 magnetic through this evening. Timing of stronger gusts may be off by a few hours. A brief shower is possible 19-21z. KEWR TAF Comments: Wind direction likely to stay left of 310 magnetic through this evening. Timing of stronger gusts may be off by a few hours. A brief shower is possible 19-21z. KTEB TAF Comments: Timing of stronger gusts may be off by a few hours. A brief shower is possible 19-21z. KHPN TAF Comments: Timing of stronger gusts may be off by a few hours. A brief shower is possible 19-21z. KISP TAF Comments: Timing of stronger gusts may be off by a few hours. A brief shower is possible 20-22z. .OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... .Friday Afternoon...VFR. NW winds G25KT. .Saturday...MVFR or lower conditions possible by the afternoon and becoming likely towards evening. Showers at night S-SW winds G25-35KT. .Sunday...Conditions improve to VFR with showers ending. NW winds G25-30KT. .Monday-Tuesday...VFR. NW winds 20-25KT. && .MARINE... Winds will rapidly strengthen behind a frontal system today, allowing seas to build into Friday as the pressure gradient remains tight. These winds will strengthen to gales by tonight and continue into much of Friday before subsiding from west to east as high pressure builds into the area. A brief quiet period expected Fri night into Sat morning, then S-SW winds should quickly ramp up on the ocean waters Sat afternoon and on the remaining waters Sat night. Winds on the ocean waters may gust close to gale force Sat night ahead of an approaching cold front. Gales are likely on all waters on Sunday after the cold frontal passage, followed by an extended period of SCA conditions Mon into Mon night. && .HYDROLOGY... A quarter to three quarters of an inch of rain is expected across eastern Long Island and southeast Connecticut this morning, with lesser amounts further west. There is the potential for around half an inch of rainfall Saturday night along and ahead on approaching cold front. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ330- 335-338-340-345. Gale Warning from 6 PM this evening to 6 AM EST Friday for ANZ330-335-338-340-345. Small Craft Advisory until 6 PM EST this evening for ANZ350- 353-355. Gale Warning from 6 PM this evening to noon EST Friday for ANZ353-355. Gale Warning from 6 PM this evening to 6 PM EST Friday for ANZ350. && $$ SYNOPSIS...CB/MD NEAR TERM...CB/MD SHORT TERM...MD LONG TERM...DW AVIATION...BC/DS MARINE...MD/DW HYDROLOGY...CB/MD/DW

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.