Marine Weather and Tide Forecast for Port Chester, NY

KEY MESSAGES
1) Expect showers, possibly a thunderstorm on Wednesday along and ahead of a warm front.

2) Hot and humid Thursday into Friday.

3) Cold front approaches Friday and passes through at night.

4) Temperatures remaining above normal this weekend into the beginning of next week.

DISCUSSION

KEY MESSAGE 1
Shortwave enregy will move over top a high amplitude upper level ridge along the eastern seaboard. In turn, this will send weak surface low pressure over the Great Lakes north and east, sending a warm front toward the area on Wednesday. The warm front will move through Wednesday evening. Warm advection showers, mainly scattered in coverage, will develop across the area Wednesday morning and spread west to east into the afternoon. Airmass will initially be stable and any thunderstorms that do occur will be late in the day toward evening as the airmass gradually destabilizes. PW values around 2 inches and efficient warm rain processes could result in some heavy downpours toward evening. However, storm motion will be from the west at 20-25 kt and training or clustering of cells seems unlikely at this time. Still, minor nuisance poor drainage flooding cannot be ruled out.

Cloud cover and southerly winds will keep temperatures mainly in the 70s for highs on Wednesday. Forecast highs are a few degrees above normal. It will also become noticeably more humid as dew points climb through the 60s.

KEY MESSAGE 2
Upper ridge reestablishes itself briefly on Thursday as the aforementioned shortwave energy and warm front move offshore.
However, a hot and humid airmass in wake of the warm frontal passage will be moderately to highly unstable. Environment will be weakly sheared, so no organized convection is expected at this time. Pulse severe will be possible in the high CAPE environment. The one limiting factor could be convective debris from upstream convection, which could keep temperatures a bit cooler. For the time, this looks to be more diurnally driven with scattered late afternoon/evening convection. One caveat here is that some of the guidance is suggesting a backdoor cold front that could serves as a focus, but this looks to be later in the day.

More importantly at this time, a heat advisory is in effect for heat indices of 95 to 100 on Thursday. This is for all but far eastern LI and portions of SE CT.

It becomes more uncertain heading into Friday as some of the guidance does bring a backdoor cold front across the area late Thursday night into Friday. Should this occur, how far west the boundary gets will be critical. An easterly flow behind the boundary would result in cooler temperatures than those that are currently forecast. Thus, the heat advisory was not extended into Friday. The best chance would be from NYC and points north and west. If the boundary does not make it, high heat and humidity would be more expansive on Friday.

KEY MESSAGE 3
A better organized convective event is possible with an approaching cold front late Friday into Friday night. SPC has a 15 percent probability for severe weather across the forecast area. Damaging wind looks to be the main threat.

KEY MESSAGE 4
A cold frontal passage will bring reduced humidity this weekend, however temps will remain above average with highs in the 80s and lower 90s. Temps might cool down a little for Mon and Tue, but the blended approach still yields highs in the 80s almost all areas.
Coolest spots at the shore but even mid to upper 70s progged at Montauk.

AVIATION /03Z WEDNESDAY THROUGH SUNDAY/
High pressure gradually shifts offshore. A warm front pushes through on Wednesday.

VFR through Wednesday morning. MVFR then possible with 2500-3000 kft cigs and isolated to scattered showers during the day Wednesday, with the best chances in the afternoon and evening.
An isolated thunderstorm will be possible as well, with the best chances after 22z.

Southerly flow continues overnight around 10kt or less. The flow becomes more SW on Wednesday and increases to 15kt. Winds subside Wednesday night to around 10kt.

...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

Amendments may be needed to fine tune the timing of thunderstorms Wednesday afternoon.

OUTLOOK FOR 00Z THURSDAY THROUGH SUNDAY

Thursday-Friday: MVFR or lower possible at times with chances of showers and thunderstorms in the afternoon and evening.

Saturday-Sunday: VFR.

Detailed information, including hourly TAF wind component forecasts, can be found at: https:/ www.weather.gov/zny/n90

MARINE
Marginal SCA conditions are possible Wednesday night in a southerly flow of 15 to 20 kt. Vertical temperature profile inverted offshore, so gusts should be limited to up to 25 kt with seas of 3 to 5 ft.

Otherwise, winds and seas are expected to remain blw SCA lvls through this weekend into the beginning of next week as high pres builds in from the west.

Rip Currents...

For Wednesday, there is a moderate rip current risk with SSW winds and waves around 3 ft.

For Thursday, there is a moderate rip current risk with SW winds and waves around 3 ft.

OKX WATCHES/WARNINGS/ADVISORIES
CT...Heat Advisory from noon to 8 PM EDT Thursday for CTZ005>007- 009-010.
NY...Heat Advisory from noon to 8 PM EDT Thursday for NYZ067>075- 078-080-176>179.
NJ...Heat Advisory from noon to 8 PM EDT Thursday for NJZ002-004- 006-103>108.
MARINE...None.