Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 270354 AFDOKX Area Forecast Discussion National Weather Service New York NY 1154 PM EDT Sat May 26 2018 .SYNOPSIS... A back door cold front approaches from the north and east, and moves across the region tonight into early Sunday. The front becomes nearly stationary south of Long Island through Memorial Day as high pressure builds to the north. High pressure will build into the region through midweek, then low pressure may impact the region for the end of the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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Stability is increasing with only slgt chcs now fcst into the overnight hours. Still expecting a break for several hours until the next round of precipitation moves in with the interaction of the back door cold front moving in from the north to northeast and a pair of shortwaves approaching from the SW and W. Precipitation will overspread the area generally between 08z and 12z from SW to NE. Instability will be minimal to none with precipitation mainly stratiform, especially behind the front. However, signals for a bout of heavy rain from central NJ northeastward into NYC and NJ metro. Flash Flood Watch posted.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... The back door cold front will become stationary south of Long Island early Sunday morning, 12Z to 15Z, and additional shortwave energy will move through the northeast through Sunday night into early Monday. Again with little CAPE, and instability, precipitation will be mainly stratiform. There may still be some heavier more convective elements just behind the cold front Sunday morning with the potentially for heavier rainfall as these convective elements will be slow moving. There is a high risk of rip current development at the ocean beached on Sunday. && .LONG TERM /MONDAY THROUGH SATURDAY/... A broad area of high pres will build over the region thru Wed. There will be a backdoor cfp on Tue. The timing is slightly faster than yesterday`s model suite, thereby suppressing the instability and chcs for shwrs to the s. The GFS is slower than the ECMWF and NAM, which is why pcpn is initiated closer to the cwa. The fcst remains dry. The dry wx then holds thru Wed, then increasing thetae could allow for some isold-sct shwrs and tstms on Thu. The modeling is not too aggressive attm wrt qpf, as the organized dpva is progged to remain w of the region closer to the main sys. Pops remain limited to slgt chc as a result. The main low, which is the remnants of Alberto, is progged to traverse the area Fri and Sat. This would present a better chc for organized rainfall, which could be locally hvy. The 12z data focuses the low on nrn New England, but this is likely to change over time, as is did from the prev 12z runs. Pw around 2 inches is suggested invof the low which seems reasonable based on the subtropical origins. The nbm was used for all but Tue high temps where the warmer Superblend was used. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... A cold front will stall to the south of Long Island overnight and Sunday as a few troughs of low pressure move along it. Light sct showers starting to approach from the SW may reach some of the western terminals before the main show late tonight into Sun morning, but no restrictions are expected. VFR to start with IFR developing generally between 09z and 14z. Cold front over CT and will drop to the south through 07z with a light E-NE flow developing. The front stalls south of LI through Sun with rain overspreading the area generally between 08z and 12z. IFR to LIFR conds are expected to prevail through 00z. Widespread steady rainfall may end between 18z and 21z at NYC terminals with sct showers through the remainder of the period. E-NE winds also continue through the day although speeds will increase to 10-15kt with gusts 15-20kt beginning around 12z. .OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY... .Sunday night...IFR/LIFR with rain coverage diminishing. .Monday...MVFR cigs in the morning along with slight chance of light rain, then VFR. .Tuesday-Wednesday...VFR. .Thursday...Mainly VFR. && .MARINE... With a weak pressure gradient across the waters today and tonight, winds and seas have remained below SCA levels, and are expected to remain below through tonight. An increasing NE to E flow behind a back door cold front, with high pressure building to the north will result in both winds and seas increasing to SCA levels Sunday morning and continuing into Sunday night, mainly on the ocean waters, Gusts across eastern Long Island Sound, and the bays of Long Island may be near SCA levels Sunday. However expect gusts to be more occasional, and will not issue a SCA for those forecast waters at this time. Across the ocean waters have cancelled the SCA that were in effect today and tonight, and posted a new SCA for the ocean waters Sunday and Sunday night. Winds are expected to remain blw sca lvls Mon-Thu. 5 ft seas are possible Mon on the ocean, otherwise they will stay blw sca lvls thru Thu. && .HYDROLOGY... Average basin rainfall amounts through Sunday are expected to be between 1/3 and 1/2 inch, highest along the coast. Locally heavy rainfall is possible late tonight into Sunday which could result in minor urban and poor drainage flooding. There is a low chance of flash flooding, which could result if there is any training of heavy rainfall along the frontal boundary. No significant hydrologic impacts are anticipated Sun night through Thu. There is a low potential for locally heavy rain Fri-Sat. && .TIDES/COASTAL FLOODING... Water levels may be near minor flood thresholds along the south shore back bays of Nassau County and in western Long Island Sound with the Sunday late afternoon and evening high tide cycle. Forcing for increased water levels will be increasing E-NE flow as a front stalls to the south and strong high pressure sets up E of New England, along with increasing astronomical high tides with the full moon on Tue the 29th. && .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...Flash Flood Watch until 11 AM EDT Sunday for NYZ072>075- 176>179. High Rip Current Risk from 6 AM EDT Sunday through Sunday evening for NYZ075-080-081-178-179. NJ...Flash Flood Watch until 11 AM EDT Sunday for NJZ004-006- 103>108. MARINE...Small Craft Advisory from 6 AM Sunday to 6 AM EDT Monday for ANZ350-353-355.
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&& $$ SYNOPSIS...12/19 NEAR TERM...12/19/PW SHORT TERM...19 LONG TERM...12 AVIATION... MARINE...12/19 HYDROLOGY...12/19 TIDES/COASTAL FLOODING... EQUIPMENT...

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