Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 220627 AFDOKX Area Forecast Discussion National Weather Service New York NY 227 AM EDT Mon May 22 2017 .SYNOPSIS... High pressure moves east of the area today. A series of low pressure systems will impact the area through the week, resulting in periods of unsettled weather. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Clouds continue to overspread the area tonight, although plenty of dry air remains at low levels per 00Z KOKX sounding and observations reflecting near 20 degree temperature/dew point depressions. Recent observations show very little if any rain currently reaching the ground, and would expect this trend to continue until towards day break. Last several runs of the HRRR have been indicating quick development of rain with approaching shortwave after 06z, so will need to monitor trends over the next few hours. Overnight lows of 45-55 degs are fcst, slightly lower than normal based on southeast winds off the cool Atlantic Ocean. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... Light precipitation will be possible around day break, gradually increasing into a brief period of moderate rain through the afternoon as a short wave moves through the area and warm/moist advection increases. Outside of the afternoon, model sounding profiles generally lean more towards a stratus/drizzle profile which should help to reduce overall rainfall amounts. Additionally, deterministic and ensemble models have trended southward with the heaviest rainfall, which may now skirt south of Long Island. Have reduced total QPF values to reflect these trends, with rainfall totals now expected to be around 1 to 1 and 1/2 over a broad period from today through tomorrow morning. Minor urban flooding of low lying poor drainage areas is possible, primarily associated with any locally heavier downpours that may occur with isolated thunderstorms. As southeast winds continue blowing off the cool Atlantic Ocean, day time temperatures will range 60-65 degrees. By evening, rainfall will gradually decrease from west to east. There may be a brief period of fog as moisture remains beneath the inversion until the cold front moves through leading to drier conditions overnight. Tuesday...As the upper lvl low digs SE across the Western Great Lakes, another short wave will rotate arnd the base of this low, causing cyclogenesis in the SE that will move NE toward the region, bringing our next chc of rain. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... The developing upper trough over the central U.S. will continue to amplify over the midwest and southern plains Tuesday night, then move slowly east through the end of the work week. This will result in unsettled weather through the period as a series of lows and upper level vorts move through, bringing multiple chances for rain to the region. Models are in somewhat better agreement in the large scale trough evolution, although differences continue in the timing and placement of individual shortwaves and the associated sensible weather. Based on the 12Z model suite, the general consensus is for a period of rain Tuesday night into Wednesday, then again on Thursday, with a chance of lingering showers in between. The trough begins to lift to the northeast late in the week as a ridge builds in for the weekend. This will allow for generally dry conditions for a period Friday into Saturday. Models then diverge on the placement of a shortwave undercutting the ridge, which could bring a chance of rain back to the region on Sunday. Daytime highs will be near normal through the majority of the period, before rising to a few degrees above normal by the weekend. Overnight lows will run around 5 degrees above normal through the weekend. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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Weak frontal system will move across the area the next 24 hours. Ceilings will gradually lower to IFR through late morning into early this afternoon where they will remain through Monday night. There is uncertainty with the timing of lowering conditions as well with the rain. Actual observations could be off by 2 to 4 hours from forecast. SE winds 5-10 kt overnight gradually increase during the day Monday, generally 8 to 13 kt. Occasional gusts up 15-18 kt possible. There is also a slight chance for thunder. Confidence on timing and placement is too low to include in the TAFs at this time. .OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY... .MONDAY NIGHT-TUESDAY...IFR early then gradually becoming VFR Tuesday morning. Possible late day rain near the coast. .WEDNESDAY...VFR. .THURSDAY...Possible IFR conditions in rain. Slight chance of thunderstorms Thursday evening. .FRIDAY...MVFR or lower possible in showers.
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&& .MARINE... Sub-advsy conds will remain across the waters through tonight as high pressure gradually slides off the New England coast. SE winds will increase to 15-20 kt as seas build to around 4 ft during the day Monday across the Atlantic Ocean coastal waters. Areas of fog are forecast to restrict VSBY to 1-3NM area wide through Monday evening. While winds will generally remain below SCA conditions, seas will begin to increase on Wednesday as a series of lows move over the area. SCA conditions are possible on the ocean waters Wednesday- Friday before seas begin to subside on Saturday. && .HYDROLOGY... Rainfall accumulations of a half inch to one and a half inches is possible from today through tomorrow morning. Minor urban flooding of low lying poor drainage areas is possible. Several opportunities exist for widespread rainfall during the mid- to late-week time period. Around one inch of additional rainfall is possible during this time period, although considerable uncertainty exists in the details of these events. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...FEB/GC NEAR TERM...FEB/MD SHORT TERM...GC/MD LONG TERM...FEB AVIATION...DW MARINE...FEB/GC HYDROLOGY...FEB/GC

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