Area Forecast Discussion
Issued by NWS Upton, NY

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256 FXUS61 KOKX 250001 AFDOKX Area Forecast Discussion National Weather Service New York NY 801 PM EDT Sat Mar 24 2018 .SYNOPSIS... An upper level disturbance moves through the region tonight into Sunday. High pressure builds down from southeastern Canada Sunday night through Monday night, and remains over the area through Tuesday. A slow moving cold front then approaches from the west through Thursday night and crosses the area on Friday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Forecast is on track with only minor changes made to reflect current trends. An upper level low will rotate down from Western Quebec late today and over the region tonight, while joining with a lingering shortwave trough east of new England. At the surface, a cold front associated with the Quebec upper low will moves through the region this evening. SCT-BKN instability cu expected to continue across LI/CT into this evening associated with the eastern New england trough, with isolated sprinkles drift S across E CT and E LI into early eve. Increasing cloud cover expected across the entire region tonight as the upper low sinks se. Scattered snow showers expected across E CT and E LI late tonight into Sunday morning, with shortwave forcing interacting with deeper Canadian maritime moisture in low-mid level NE flow. A dusting of snow possible across E LI/SE CT, with locally an inch of snow possible across the hills of central and eastern CT. To the west across NYC metro, NE NJ, and Lower Hud moisture will be more limited, limiting coverage of snow shower to isolated. With cloud cover and mixed low-level temps will likely run in the upper 20s interior, to lower to mid 30s city/coast. near to slightly below seasonable. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Axis of upper low slides southeast of the region Sunday morning, with weaker backside shortwave passing through the region Sunday evening. This entire low then should slowly slide east Sunday night. Morning snow showers should taper off by midday. Otherwise, Sct to Bkn instability cu likely remain through the day under troughing and cold pool instability, highest coverage LI/CT. Potential for isolated snow showers or flurries across E CT/E LI in the afternoon ahead of next shortwave, with just a few flurries/sprinkles possible elsewhere. Gusty NE winds, caa, and cloud cover will make for an unseasonably chilly Sunday. Highs will likely struggle into the upper 30s and lower 40s, a good 10 degrees below seasonable levels. Drying conds Sunday night in wake of shortwave and with rising heights. Temps will continue to run well below seasonable though, with potential for temps to drop well down into the lower 20s across outlying areas with decoupling. && .LONG TERM /MONDAY THROUGH SATURDAY/... Omega block pattern set up over the CONUS during the beginning of the long term period, with a trough and cut off low over the open waters off the East Coast and a trough over the Rockies, with deep layered ridging over the Eastern Great Lakes Region slowly building into the Eastern US. This will provide dry weather through at least Tuesday night with surface high pressure over southeastern Canada building south into the Northeast. Our region will be between this coastal storm well off shore that is forecast to meander and weaken over the open ocean waters through the middle of the week as a surface cold front slowly approaches from the west. A piece of this high gets pushed south of the area and a warm front lifts well north Wednesday night. As the cold front approaches it will also weaken, with very little moisture to work with. So, just a slight chance to chance of precipitation is possible from mid to late week. Temperature forecast later in the week may be difficult as there are some differences in how the models handle the warm front. 12Z GFS is very progressive in lifting the front north, while the 12Z ECMWF keeps it south of the area or in the vicinity through the end of the week. If the GFS is right, then warmer temperatures are in store for the end of the week, possibly breaking 60 in the New York City metro area on Thursday and Friday, while cooler temperatures would prevail in the ECMWF solution. Outside of that, temperatures will be cooler than normal to start off the week, then warm to slightly above normal for the middle of the week. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... A cold front will pass through from the north tonight into Sunday. VFR initially but clouds increase and lower overnight into early Sunday with MVFR ceilings expected. Some snow showers are also forecast which will bring MVFR to possibly IFR visibilities for brief periods of time in a general timeframe of 11Z-16Z Sunday. IFR will be more probable if there is a light snow accumulation of a few tenths of an inch. This time window could vary 1-2 hours from forecast. The chances for these snow showers are higher outside the city terminals. N-NNE flow tonight 5-10 kt will become gusty for coastal terminals Sunday. Flow will become NE 10-15 kt with gusts in the 20-25 kt range for these coastal terminals Sunday. Gusts are still possible farther inland but may not be as frequent. .OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY... .Sunday Night...Mainly VFR. NE winds G20KT. .Monday...VFR. NE winds G15-20KT. .Tuesday...VFR. .Wednesday...Mainly VFR, chance MVFR in -SHRA, mainly at night. .Thursday...Mainly VFR, chance MVFR in -SHRA late at night. && .MARINE... Sub SCA conditions continue through this evening, then strengthening N/NE flow tonight in wake of a cold front. SCA conds expected to develop on the ocean waters and possibly eastern nearshore waters Sunday morning, continuing into Mon. In response, ocean seas will build to SCA levels on the ocean Sunday, and likely continuing at these levels through midweek as NE swells affect the waters in response to a large, strong and stubborn Atlantic low. Waves will range from 5 to 9 ft through Tuesday, with waves slowly diminishing Tuesday night into Wednesday night as the flow weakens. Waves fall below 5 ft by Wednesday morning and remain below SCA criteria through the end of the week. Wind gusts of 25 to 30 kt possible on the ocean waters Monday through the first half of Monday night as the flow slowly weakens. Winds remain below SCA criteria through the end of the week with weak pressure gradient. && .HYDROLOGY... Rapid snow melt will continue into the weekend as high temps climb into the 40s. Although gradual rises are expected on areas stream and rivers, no hydrologic problems are anticipated through Thursday. && .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 6 AM Sunday to 11 AM EDT Monday for ANZ330-340-345-350-353-355. && $$ SYNOPSIS...JP/NV NEAR TERM...JP/NV SHORT TERM...NV LONG TERM...JP AVIATION...JC MARINE...JP/NV HYDROLOGY...JP/NV EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.