Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 150906 AFDOKX Area Forecast Discussion National Weather Service New York NY 406 AM EST Thu Feb 15 2018 .SYNOPSIS...
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A warm front lifts to the north this morning, stalls to the north, then pushes back south as a cold front late tonight and Friday morning. A second cold front races to our south Friday afternoon. High pressure briefly builds across the area Friday night and Saturday before giving way to coastal storm that passes to the southeast Saturday night into Sunday morning. High pressure then returns Sunday into early Monday. A warm front moves through late Monday followed by a slowly approaching cold front through midweek.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Light rain should come to an end by 10Z as supporting 500 hPa shortwave exits to the east as northern stream shortwave ridging builds in this morning, then exits to the ENE this afternoon. Subsidence associated with this shortwave ridge should keep things dry during the daylight hours. However, abundant low level moisture trapped under an inversion around 950 hPa and a second one around 825 hPa should keep the area under a overcast to maybe mostly cloudy sky. Given only expecting minimal sunshine today, leaned towards cooler guidance for highs. Highs should generally be in the lower to mid 50s as a result, except upper 50s to maybe 60 across Urban NE NJ and NYC. Record highs may be approached today, especially if a bit more sunshine occurs than expected. See the climate section of the AFD for details.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
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A series of 700-500 hPa shortwaves cross the area tonight and Friday triggering periods of light to moderate rainfall. Mainly from mid evening into early Friday afternoon. Lows tonight should be around 5 degrees above normal and highs on Friday around 15 degrees above normal.
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&& .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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A progressive flow across the Lower 48, largely dominated by the southern branch of the polar jet, will undergo amplification by early next week. A upper trough digs south across the intermountain west, while a high amplitude ridge builds off the southeast coast. The latter of which may bring record warmth to the area next week. First though, a fast moving winter storm will follow on the heels of a fleeting shot of cold air Friday night into Saturday. The GFS is the southernmost operational member in taking low pressure to the south and east of the area Saturday night into Sunday morning. It is also weaker than the ECMWF and NAM. This is likely due to its poor handling of cold air damming east of the Appalachians as high pressure quickly races to the east on Saturday. Granted, the location of the high is not ideal for damming, nor for a moderate to heavy snow event. However, the fast development of the low along the Mid Atlantic coast Saturday afternoon, which quickly passes to the southeast, may only result in a short period of weak onshore flow. A SE flow along the coast is typically a snow to rain event, but in this case a rain/snow mix at the onset may go to all snow fairly quickly as winds shift quickly to the NE. In addition, a deep- layered W-SW flow does not look to erode the cold air aloft, with the main question thus being the boundary layer temperature. With about quarter to half inch of liquid across the area, there is the potential for advisory level snows (2 to 4 inches). Should the ECMWF`s wetter solution come to fruition, possibly a low end warning event (around 6 inches). The best chance for this to occur would be along or just inland from the coast due to the higher QPF forecast, provided the event can be mainly in the form of snow. Temperatures are forecast to be in the 20s inland and in the lower 30s along the coast. Thereafter, a significant warmup ensues through the middle of next with a deep-layered SW flow to develop as high pressure strengthens off the eastern seaboard. Highs Tuesday and Wednesday may get to around 60 across parts of NYC and the interior, but it will be considerably cooler along the coast due an onshore flow.
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&& .AVIATION /08Z THURSDAY THROUGH MONDAY/...
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TAFs updated as ceilings are taking longer than forecast to fall to IFR. Many terminals still at VFR or MVFR. Only exception is BDR which has become LIFR. Cigs are expected to fall through 12Z, however a bit unsure whether or not we reach MVFR vs IFR at many of the terminals. Cigs should improve a little this afternoon. There is a chance that a terminals across NYC and points west become VFR for a few hours. East of NYC, conditions are expected to remain MVFR/IFR. Additional rainfall tonight should also allow conditions to fall to IFR just about everywhere tonight. Otherwise, A prolonged period of SW flow can be expected until a cold front passes through on Friday. Winds will be light thru 12z, then winds increase again during the day. ...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: Amendments likely today for changing flight categories. The afternoon KJFK haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KLGA TAF Comments: Amendments likely today for changing flight categories. The afternoon KLGA haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KEWR TAF Comments: Amendments likely today for changing flight categories. The afternoon KEWR haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KTEB TAF Comments: Amendments likely today for changing flight categories. KHPN TAF Comments: Amendments likely today for changing flight categories. KISP TAF Comments: Amendments likely today for changing flight categories. .OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY... .Tonight into Friday...Rain likely with MVFR or lower. NW winds G25KT Friday afternoon/evening. .Saturday...VFR. .Saturday Night...MVFR or lower with a chance of snow. .Sunday...Improving to VFR. .Monday...Initially VFR conditions lowering to MVFR or lower late with rain.
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&& .MARINE...
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Expect seas to remain just below 5 ft today in response to a persistent SE-S swell. So with winds mainly 10 kt or less, sub-Small Craft Advisory (SCA) conditions are likely on the coastal ocean waters and expected on the non-ocean waters. Will have to monitor seas towards the outer edge of the coastal ocean waters to see if they end up creeping up over the 5 ft SCA threshold today. As the pressure gradient tightens tonight, winds increase to up to 15 kt and help to build seas on the coastal ocean waters to SCA levels. SCA level seas should persist into at least Friday evening, with SCA wind gust over the coastal ocean waters most likely Friday afternoon/evening. On the non-ocean waters, there is a chance for gusts to SCA levels from Friday afternoon into Friday night, but confidence in this is not as high as for SCA conditions over the coastal ocean waters. As a result, have issued a Small Craft Advisory only for the coastal ocean waters from midnight tonight through midnight Friday night. If confidence increases, there is a potential for an SCA to be issued for all or part of the non-ocean zones for Friday/Friday night as well. NW gusts 25-30kt are likely to continue through the first half of Friday night behind the cold front. Winds and seas are then expected to remain below SCA levels Saturday through Monday. There is the potential for marginal SCA conditions Saturday night into Sunday morning as low pressure passes to the south and east.
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&& .HYDROLOGY...
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Around 1/3 to 1/2 inch of rain is expected from tonight into Friday afternoon. No hydrologic impact is expected. It should be mainly dry Friday night and Saturday. Liquid equivalent precipitation Saturday night into early Sunday is expected to range from 1/4 northwest to around 1/2 inch through coastal Connecticut and across Long Island. However, no hydrologic impacts are anticipated this weekend into early next week.
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&& .CLIMATE...
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Record high for Today (2/15) Location.......Record High/Year....Forecast High Newark..................76/1949.........60...... Bridgeport..............60/1954.........51...... Central Park............73/1949.........59...... LaGuardia...............74/1949.........58...... J F Kennedy.............62/1949.........55...... Islip...................57/1984.........55......
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&& .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...
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CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from midnight tonight to midnight EST Friday night for ANZ350-353-355.
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&& $$ SYNOPSIS...Maloit/DW NEAR TERM...Maloit SHORT TERM...Maloit LONG TERM...DW AVIATION...BC/JMC MARINE...Maloit/DW HYDROLOGY...Maloit/DW EQUIPMENT...

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