Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 151631 AFDOKX Area Forecast Discussion National Weather Service New York NY 1131 AM EST Thu Feb 15 2018 .SYNOPSIS... A warm front lifts to the north through this afternoon, stalls to the north, then pushes back south as a cold front late tonight into 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 a 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. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Extended the SPS for Northern CT zones in the early portion of this afternoon with fog holding in. BUFKIT soundings show abundant low level moisture trapped under an inversion around 950 hPa and a second one around 825 hPa. This should keep the area under a overcast to mostly cloudy sky. Even the GFS and RAP forecast soundings which tend to be less generous as far as inversions go, still have good capping into the early portion of the afternoon with most modeling. GOES-16 showing thinning of the clouds entering far NW zones. As this translates east there may be some eroding with more of a haze as opposed to fog in some locations. This has already happened across NYC and surrounding locations. Continue to lean to the cooler guidance for highs today as expecting only minimal sunshine today. Highs should generally be in the lower to middle 50s as a result, except upper 50s to maybe 60 across Urban NE NJ and NYC. Therefore record highs looking less likely for today. There may be a few more breaks in cloud cover late in the day as indicated by GOES data, but with lower sun by then it may be too late to have an impact on temperatures / records.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... 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. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... 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. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... A weak trough remains over the region today. Low to moderate confidence forecast as flight categories very throughout the tri-state terminals. Primarily IFR conds for KBDR/KISP/KHPN/KGON with primarily MVFR conditions elsewhere through early afternoon. Conds then improve by one category this afternoon, but timing could be off by 1-2 hours. SW winds around 10 mph. 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: Cigs may briefly lower to 600-900 ft or even improve to VFR at times this morning. Chance that prevailing VFR does not occur at all this afternoon and instead remain MVFR. The afternoon KJFK haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KLGA TAF Comments: Slight chance of brief cigs 700-900 ft this morning. Chance that prevailing VFR does not occur at all this afternoon and instead remain MVFR. The afternoon KLGA haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KEWR TAF Comments: Cigs may briefly lower to 600-900 ft or even improve to VFR at times this morning. Chance that prevailing VFR does not occur at all this afternoon and instead remain MVFR. The afternoon KEWR haze potential forecast is YELLOW...which implies slant range visibility 4-6SM outside of cloud. KTEB TAF Comments: Cigs may briefly lower to 600-900 ft or even improve to VFR at times this morning. Chance that prevailing VFR does not occur at all this afternoon and instead remain MVFR. KHPN TAF Comments: Improvement to VFR this afternoon might not occur. KISP TAF Comments: Improvement to VFR this afternoon might not occur. .OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY... .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. && .MARINE... 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. && .HYDROLOGY... 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. && .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... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from midnight tonight to midnight EST Friday night for ANZ350-353-355. && $$ SYNOPSIS...Maloit/DW NEAR TERM...JE SHORT TERM...JE/Maloit LONG TERM...DW AVIATION...JC MARINE...Maloit/DW HYDROLOGY...Maloit/DW EQUIPMENT...

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