Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 220804 AFDOKX Area Forecast Discussion National Weather Service New York NY 404 AM EDT Sat Sep 22 2018 .SYNOPSIS... A cold front passes through early this morning before stalling south of Long Island into tonight. High pressure gradually builds in from the Great Lakes through the remainder of the weekend. A frontal system will then impact the area Tuesday into Wednesday, ending with a cold frontal passage Wednesday night. High pressure returns for the end of the week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Weakening line of showers ahead of a cold front becoming widely scattered with only a few light returns remaining on radar. Showers will continue to dissipate as they run into more stable air but have kept chance PoPs over the next few hours. The cold front will continue to push off the coast this morning and settle south of the region. A noticeably cooler and drier northerly flow will set up as high pressure approaches from the Great Lakes. Clouds will be quick to clear this morning but there could be some mid-high level clouds across the area this afternoon as mid-level shortwave energy passes through. It will start to feel like Fall today as dewpoints fall into the upper 40s to lower 50s with highs ranging in the low to mid 70s. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/... The high will continue pushing westward, and the region will be under a more easterly flow. The stalled front will linger off the Delmarva with the GFS indicating the front pushing back north with some rain late Saturday night into early Sunday morning. Other models continue to indicate the front remaining well to the south, so have kept a dry forecast through Saturday night. Overnight min temperatures will be near seasonable in the upper 40s for the northern areas and in the 50s around NYC metro and across Long Island as cloud cover will mitigate radiational cooling. High pressure remains in control on Sunday with temperatures a few degrees cooler than Saturday with an easterly wind and a partly sunny sky. There is a moderate risk for the development of rip currents at the ocean beaches Saturday morning, with a low risk in the afternoon and on Sunday as winds diminish and seas subside. && .LONG TERM /MONDAY THROUGH FRIDAY/... A confluent flow across eastern Canada and the northeast will allow for strong high pressure to pass to the north through Monday. There is some concern with a frontal wave associated with a shearing mid-level shortwave trough, but will maintain a dry forecast on Sunday with some morning clouds mainly near the coast. Any light rain should stay south of Long Island. The GFS which does produce some measurable rain across the NYC metro and Long Island appears to be overdone based on the depth of dry air and the northern placement of the upper jet in comparison to the model consensus. The weather then takes a downhill swing for the midweek as an upper trough out west races eastward with a frontal system impacting the area Tuesday into Wednesday. First of which will be with overrunning rain Monday night into Tuesday night and then with scattered convection on Wednesday. The cold front follows Wednesday night. Additional timing issues have now risen with the GFS trending against the model suite by stalling the front Wednesday night into Friday, with multiple waves of low pressure riding along the front. In this scenario, the kicker will be with a late week cold frontal passage. All the global models support the late week kicker, the differences though arise with the lead shortwave trough lifting out to the NE Wednesday night into Thursday. The magnitude of this feature and its wavelength separation with the next upper trough/surface frontal system, will determine whether the first boundary makes it through. Even the GGEM which sends the first front east of the area Wednesday night, is close enough for a coastal low to impact the area Thursday night into Friday. Thus, there remains quite a bit of uncertainly for the Thursday into Friday timeframe and have maintained a low chance for rain at this time. Seasonable temperatures will start the week, but it then gets warm and humid Wednesday in the warm sector. The end of the week is a bit tricky depending on the placement of the aforementioned frontal boundary. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... A cold front will pass through late tonight, followed by building high pressure. MVFR cigs to start, plus a few showers with cold fropa, will give way to VFR conds. S-SW winds before cold fropa may shift W and gust over 20 kt with cold fropa at some terminals, most likely KHPN/KTEB/KLGA. WNW winds with gusts either side of 20 kt expected throughout this morning, veering NNW and diminishing slightly this afternoon, then becoming N-NE less than 10 late late this afternoon into tonight. .OUTLOOK FOR 06Z SUNDAY THROUGH WEDNESDAY... .Late Saturday night-Sunday...VFR. .Monday...VFR. .Tuesday and Wednesday...Showers with MVFR or lower flight cat possible. SE winds G25KT on Tue. && .MARINE... Minimal SCA conds continue on the far ern Sound and on the ocean waters, with gusts up to 25 kt and ocean seas as high as 5 ft. Left end time of SCA alone on those waters (10Z ern Sound and 18Z ocean), but have a feeling winds after cold fropa will remain below criteria, and will be able to cancel earlier than that. E winds strengthen Mon into Mon night and continue into Tue ahead of an approaching warm front. SCA conditions are likely to develop during this time, with on outside chance of gale force gusts on the ocean waters. High seas are likely to linger into Wed, with a S flow as the warm front passes to the N and a cold front approaches later that day. && .HYDROLOGY... No hydrologic impacts expected through the weekend. A frontal system could bring locally heavy showers/tstms Tue into Wed, first via warm fropa on Tue, then again via trailing cold fropa on Wed. Anticipate only localized nuisance impacts at this early point. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ350- 353-355. Small Craft Advisory until 6 AM EDT early this morning for ANZ330. && $$ SYNOPSIS...CB NEAR TERM...CB SHORT TERM...CB LONG TERM...DW AVIATION...Goodman MARINE...Goodman HYDROLOGY...CB/DW EQUIPMENT... is the U.S. government's official web portal to all federal, state and local government web resources and services.