Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 152057 AFDOKX Area Forecast Discussion National Weather Service New York NY 357 PM EST Wed Nov 15 2017 .SYNOPSIS...
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A frontal system approaches tonight and will move across the region on Thursday. A strengthening low pressure will move up the New England coast along the front Thursday afternoon and night. A series of cold frontal passages will take place through early next week, one from late Saturday night into Sunday morning, and another from late Tuesday night into Wednesday morning, both followed by building high pressure.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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High pressure moves off the New England coast this evening ahead. Surface ridge axis will also shift offshore as moisture below inversion around 4-5 kft continues to advect in from the south. At the same time, middle and upper level moisture increases leading to skies becoming overcast through the night. Upper shortwave tracks across the Great Lakes tonight which sends a frontal system towards the region. Potent vorticity energy within the trough is progged to amplify the shortwave trough as it approaches late tonight. Showers increase in coverage towards day break Thursday as the front encounters increasing moisture and large scale synoptic lift. Lows tonight will range from the upper 30s inland to the lower and middle 40s near the coast.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
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The cold front will be moving across the NYC metro early Thursday morning. Parent low pressure across the northern Great Lakes gradually weakens as a new secondary low develops just south of Long Island Thursday morning. This is in response to the strong vorticity energy approaching the coast and increasing upper divergence. The secondary low is progged deepens as it moves near Montauk or just to the east in the afternoon and then quickly up into the Gulf of Main Thursday evening. The cold front will link up with this low and enhance the showers for eastern Long Island and southeast Connecticut. Fast movement of this system will limit rainfall amounts, but totals averaging around a half to possibly three quarters of an inch are possible across eastern Long Island and southeast Connecticut with a few tenths closer to NYC. Showers will first taper off around NYC metro by middle morning and then last out east in the early afternoon. Some convective elements are likely to occur with the enhancement from the new low, but forecast thermal profiles look stable, so have removed mention of thunder. Gusty westerly winds are expected Thursday afternoon and evening as the low lifts up into New England. The strongest gusts, 25-35 mph, are likely Thursday night as the pressure gradient strengthens between the low and building high pressure. Highs on Thursday should be able to rise into the 50s as the main push of colder air holds off until Thursday night when temperatures fall back into the 30s areawide.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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A progressive flow regime aloft will remain in place into the middle of next week, with the passage of amplifying upper troughs and associated cold fronts every 3 days or so, preceded by milder air with temps close to average, and brief shots of cold temps ushered in on gusty NW winds. This progressive pattern will prevent any really stormy weather from impacting the local area as associated surface lows develop well to the north and east. In the wake of one such trough passage on Thu, high pressure will build in daytime Fri into Fri evening on a gusty NW flow. Winds should then diminish late Fri night into Sat, with a S-SW return flow and deep layer WAA quickly developing on Sat ahead of the next trough. Some light precip could arrive NW of NYC as early as Sat morning, with temps cold enough for any precip during that time to be in the form of light snow or flurries before temps quickly warm up into the upper 40s and 50s Sat afternoon, then stay mild into Sat night before cold fropa late Sat night. Most of the associated precip with this system should fall late Sat night as a strong cold front and potent, negatively-tilted mid level shortwave trough sweep across. Winds on Sunday are then likely to reach advy criteria, with the strongest winds in NYC metro/Long Island and in the higher interior elevations, ushering another shot of cold wx from Sunday night into Mon night, with low temps in the 20s/30s and highs on Mon only 40-45. Temps should once again moderate closer to avg on Tue ahead of the next cold front, then return to below avg Wed and likely remain that way into Thanksgiving Day. This last frontal passage looks moisture- starved, with only slight chance PoP forecast Tue night.
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&& .AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
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A warm front approaches the region tonight and Thursday morning, quickly followed by a cold frontal passage. MVFR ceilings will develop across the region this evening. However, there`s a low chance some IFR conditions develop after 00Z around city terminals as depicted in the NARRE guidance. Showers work into the area after midnight with a period of IFR likely Thursday morning. VFR returns by mid day. SE winds below 10 kt this evening. On Thursday, winds become W and increase to near 15 kt with some gusts to 25-30 kt likely by midday after the frontal passage. 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: Timing of MVFR conditions may vary by 1-2 hours. Low chance of IFR conditions after 00z. Timing of Winds gusts on Thursday may vary by 1-3 hours. KLGA TAF Comments: Timing of MVFR conditions may vary by 1-2 hours. Timing of Winds gusts on Thursday may vary by 1-3 hours. KEWR TAF Comments: Timing of MVFR conditions may vary by 1-2 hours. Low chance of IFR conditions after 00z. Timing of Winds gusts on Thursday may vary by 1-3 hours. KTEB TAF Comments: Timing of MVFR conditions may vary by 1-2 hours. Timing of Winds gusts on Thursday may vary by 1-3 hours. KHPN TAF Comments: Timing of MVFR conditions may vary by 1-2 hours. Timing of Winds gusts on Thursday may vary by 1-3 hours. KISP TAF Comments: Timing of MVFR conditions may vary by 1-2 hours. Timing of Winds gusts on Thursday may vary by 1-3 hours. .OUTLOOK FOR 21Z THURSDAY THROUGH MONDAY... .18z Thursday...MVFR or lower in showers, mainly in the morning. W- NW winds G20-30KT possible in the afternoon. .Thursday night-Friday...VFR. NW winds G25-30KT, strongest Thursday night. .Saturday...Sub VFR conditions possible by the afternoon and becoming likely towards evening. S-SW winds G25-35KT. .Sunday...Conditions improve to VFR. NW winds G25-30KT. .Monday...VFR. NW winds 20-25KT.
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&& .MARINE...
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A frontal system will approach the waters tonight and move across Thursday morning. At the same time, low pressure will develop over the eastern ocean waters in the morning and then move into New England by Thursday evening. Winds and seas on the ocean will gradually increase to SCA levels Thursday morning into the afternoon. As the low moves up into the Gulf of Maine Thursday evening, gales are expected on all waters. Have adjusted the start time of the SCA to 15z on the ocean and 18z on the non-ocean zones. The gale watch has been converted to a gale warning on all waters for Thursday night. The winds on the non-ocean zones will likely fall to SCA levels on Friday, but gales should continue on the ocean west of Moriches inlet through the morning, and east of Moriches inlet into the afternoon. Gales should continue on the ocean into daytime Friday, and could also be possible on the easternmost Sound and bays of Long Island in the morning, while SCA conds prevail otherwise. 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.
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&& .HYDROLOGY...
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One half to three quarters of an inch of rain is expected across eastern Long Island and southeast Connecticut late tonight through Thursday afternoon, with lesser amounts further west. Otherwise, no significant hydrologic impacts are anticipated through next week.
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&& .TIDES/COASTAL FLOODING...
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A coastal flood statement has been issued for the south shore back bays of Queens and Nassau county for Thursday morning high tide. This is due to a strengthening SE flow tonight will lead to water levels just touching minor coastal flooding benchmarks. Elsewhere, water levels are likely to fall short. There is a small chance the statement will need to be upgraded to an advisory if trends in tide levels are higher than currently expected. Winds shifting to the W and NW Thursday afternoon and evening will significantly lower water levels through the end of the week.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from 1 PM to 6 PM EST Thursday for ANZ330- 335-338-340-345. Gale Warning from 6 PM Thursday to 6 AM EST Friday for ANZ330- 335-338-340-345. Small Craft Advisory from 10 AM to 6 PM EST Thursday for ANZ350-353-355. Gale Warning from 6 PM Thursday to noon EST Friday for ANZ353- 355. Gale Warning from 6 PM Thursday to 6 PM EST Friday for ANZ350.
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&& $$ SYNOPSIS...Goodman/DS NEAR TERM...DS SHORT TERM...DS LONG TERM...Goodman AVIATION...IRD MARINE...Goodman/DS HYDROLOGY...Goodman/DS TIDES/COASTAL FLOODING...

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