Area Forecast Discussion
Issued by NWS Upton, NY

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599 FXUS61 KOKX 300604 AFDOKX Area Forecast Discussion National Weather Service New York NY 204 AM EDT Mon Jun 30 2025 .SYNOPSIS... A cold front slowly drifts south of the area and brief weak high pressure builds in behind it. The aforementioned boundary then lifts north as a warm front late Monday into Monday night, followed by a cold frontal passage Tuesday night. Weak high pressure will be in control mid week. A cold front approaches and moves through late Thursday into Thursday night, followed by high pressure returning Friday into next weekend. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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Raised low temperatures slightly for parts of Eastern Long Island and added in patchy fog there as well as SE Connecticut coast. Otherwise, forecast on track. Min temperatures forecast still in a range from the lower 60s to the lower 70s. A cold front south of the area continues to slowly drift south tonight as brief weak high pressure builds in from the north. Aloft, the flow remains mainly zonal tonight. Mostly clear skies expected for tonight. Combined with light winds expecting decent radiational cooling conditions so went with MOS consensus for low temperatures for most locations. This may also allow for some patchy radiation fog in the early morning hours. Added in patchy fog for coastal portions of the area across Eastern Long Island and SE Connecticut where temperature and dewpoint depressions were lower and thereby low level saturation will be easier to obtain
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&& .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/... Heights rise at least the first half of Monday with shortwave upper level ridging ahead of a digging trough over the Mid-West. Weak high pressure over the area dissipates and a warm front approaches from the south. This warm front is expected to push north of the area sometime late Monday into Monday night. We will be warm sectored Monday until a pre-frontal trough and cold front swing through late Tuesday into Tuesday night. Much of Monday remains dry with partly cloudy skies. Late in the day as the warm front approaches, isentropic and mid-level shortwave lift could bring some showers to the area. Chances for this linger into Tuesday morning. Plenty of elevated instability is still seen in forecast soundings and kept thunder chances in during this time. Depending on what time the warm front pushes north, much of Tuesday morning/early afternoon should actually be dry. There is some uncertainty also in how much we can break out, but given we`ll be in the warm sector and some hints from forecast soundings there will likely a be brief period Tuesday morning with mostly sunny skies. Forecast soundings also show decent mixing on Tuesday (with the NAM even mixing up to 850mb). This gave enough confidence to lower NBM Tds that usually have a higher bias anyway. Thinking with the mixing we likely top out with Tds in the lower 70s. High temperature forecast remained the same, but given lower Tds now have lower heat index values and we likely fall short of the 1 day Heat Advisory criteria of 100. However, this will need to be monitored as Tds can still trend back up. Heights start to fall more rapidly aloft as we get into the late Tuesday period. This combined with lift from an approaching pre- frontal trough/cold front will spark showers and thunderstorms likely somewhere just west of the area. Thunderstorms should have no problem developing given plenty of CAPE. Using MLCAPE given the deeper mixed layer shows a model consensus of about 2000 J/kg, which can definitely end up being higher. This combined with decent shear (0-6km bulk shear 30-35 kt) will likely allow some storms to organize and become severe. At this time damaging wind gusts would be the primary hazard, but the CAPE profile is deep and wide enough to support large hail as well. These showers and thunderstorms will likely produce heavy downpours given an environment with 2-2.25 inches of pwat. Early look at longer range CAMs do show potential for 1+ per hour rainfall rates. However, storm motion is expected to be fast and at this time minor urban and poor drainage flooding seems more likely than flash flooding, but an instance of flash flooding can not be completely ruled out. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... * Seasonably warm and humid through Thursday * Less humid towards the 4th of July A cold front is forecast to be situated just offshore beginning Wednesday morning. There may be some lingering showers across Long Island early Wednesday morning, but for the most part, the forecast area will be dry. High pressure builds in behind it and will be in control Wednesday through Thursday morning with dry conditions. Humidity levels drop somewhat for Wednesday and Thursday as dew points slowly fall into the low to middle 60s. A cold front approaches Thursday and at this time NWP is indicating some dynamics and frontal forcing with this boundary, enough for the chance for thunderstorms for portions of the forecast area, with highest chances across the Lower Hudson Valley. May have to bump up POPs with next forecast package as ECMWF, GFS, and Canadian deterministic models show more in the way of precipitation associated with this cold front late Thursday as compared to previous forecast runs. If this trend continues, showers and thunderstorms will be more likely. Lower humidity levels expected later in the week, towards the 4th of July holiday and into the first part of the weekend with dew points falling into the 50s and lower 60s by Saturday. Would not be surprised to see even lower dew points as models typically have a hard time handling humidity levels, especially in the long term. Conditions are expected to remain mainly dry Friday into next weekend with high pressure in control. Humidity levels climb Saturday night as a warm front lifts north of the area. Slight chance for showers and thunderstorms Sunday with the approach of another cold front to the west. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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High pressure weakens today with a warm front approaching from the south tonight. VFR through the daytime. MVFR possible this evening, but more likely occurring after around midnight tonight with showers. IFR east of the city terminals late tonight. Thunder possible anytime starting this evening, however probability is too low to include in TAFs. Light NE to variable winds through most of the morning push, becoming SE this afternoon 5-10kt, then more southerly late in the day. S to SW winds 10kt or less tonight. NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Amendments possible to refine timing of showers and MVFR. Iso shra/tstm possible as early as 20-21z. .OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY... Monday night: MVFR/IFR. Showers and a slight chance of tstms. Tuesday: MVFR/IFR through mid-morning with a shower/tstm possible. VFR thereafter with a chance of MVFR or lower in afternoon and evening showers and possible thunderstorms. Wednesday: VFR. Thursday: A slight chance of an afternoon/evening shower or thunderstorm with brief MVFR or lower possible. Friday: VFR. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/www.weather.gov/zny/n90
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&& .MARINE... Some patchy fog added for waters surrounding Eastern Long Island towards early Monday morning. Sub SCA conditions expected up until Tuesday afternoon when a S/SW strengthens. This is will likely only impact the ocean waters, with 5 foot seas and 25 kt gusts, but there is potential for the gust forecast elsewhere to trend upward. Gusts likely die down Tuesday night, but 5 ft seas linger into Wednesday morning. The eastern ocean zone may start of Wednesday with 5 ft seas, but will be diminishing through the day. Sub-SCA conditions are expected from Wednesday night through Sunday with a leak of any strong pressure gradients over the region. && .HYDROLOGY... No hydrologic impacts are anticipated through Monday. A half inch to inch of rain is currently forecast for Tuesday into Tuesday night on average. Locally higher amounts are possible, and there is at least a low chance for flash flooding to occur. Minor poor drainage flooding would be more likely. No hydrologic concerns thereafter. && .TIDES/COASTAL FLOODING... There is a moderate risk of rip current development across the ocean beaches Monday and a high risk of rip currents on Tuesday. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ AVIATION...JC