Marine Weather and Tide Forecast for Groton, CT

KEY MESSAGES
1) Summer-like warmth builds this weekend into Wednesday.
Potential for isolated tstm activity Mon and Tue aft/eve west of the Hudson R, with scattered activity with cold frontal approach Wed aft/eve.

2) Cold water safety concerns for this weekend with good boating weather, and water temps still in the lower 50s.

DISCUSSION

KEY MESSAGE 1
Upper low slide east this evening with any diurnal shower activity across southern CT and E LI coming to an end and skies gradually clearing. Heights rise tonight with flat upper flow this weekend, and surface high pressure sliding off the SE US coast, allowing for a warmer airmass to begin advecting into the region from the west.

With 850 hpa temps rising to around 10C on Saturday, strengthening S/SW flow and deep mixing away from the southern and eastern coasts, air temps will rise well into 70s for much of the region. Lower 80s for NE NJ and adjacent NYC metro. Upper 60s to lower 70s along south coastal communities, with flow off low 50s degrees waters.

A shortwave sliding through northern New England and Canadian Maritimes Sat Night into Sunday, will have a weak cold front moving through the areas Saturday Night. Potential for a few showers with this feature into Sunday morning with weak forcing and elevated instability as well as moisture pooling.

High temps likely reach into the 80s across most of the area on Sunday, with W/WNW flow and deep mixing to 850hpa temps rising to around 14c teens to start the day, before giving way to afternoon south coast seabreezes. This should allow for highs 10-15F degrees above seasonable. Highs likely get into the upper 80s across metro NE NJ, with lower 80s to 85 quite possible for all but the immediate shoreline if offshore flow materializes as expected. That would put BDR and ISP close to record highs Sunday, which is 85 set back in 1974.

Upper ridging builds in early next week, anchored by Bermuda high pressure, bringing in the warmest airmass of the season by Tue/Wed. One caveat, is that as a northern stream shortwave digs thru the Canadian Maritimes Sunday Night/Monday it will bring a backdoor cold front thru the region Sunday Night. This will result in an onshore low-level flow on Monday. So despite 850 HPA temps rising solidly into the mid teens aloft, a maritime influence will limit mixing and keep south and eastern coastal areas in the upper 60s to lower 70s. Latest NBM guidance may be a tad too warm for coastal areas on Monday, although a weak flow in the morning could allow for rapid heating during the morning hours. Areas west of the Hudson River, with reduced maritime influence and deeper mixed layer likely getting into the lower 80s-85 (10-15 degrees above seasonable). Potential for late day isolated tsra activity west of the Hudson, and then Monday Night areawide, with warm frontal approach/passage and weak vorticity rounding the ridge in a marginally unstable (elevated)/weak shear environment.

The region will be solidly warm sectored Tue/Wed, with 850 hpa temps continuing to rise into the upper teens. With S/SW flow and deep mixing this will likely result in the warmest temps of the season so far, particularly away from south and east coasts. Highs 15 to 25 degrees above normal likely for Tuesday and Wednesday across NYC/NJ metro and interior, and at least 10 to 15 above for coastal areas.
At this time, forecast highs fall short of record highs (mid to upper 90s). NBM 5.0 guidance has been lowered a tad, based on synoptic set- up and concerns bias algorithms are over- correcting as we quickly transition into anomalously warm airmass. Nonetheless, widespread highs in the lower to mid 90s across NYC/NJ metro and areas to the N&W look likely. With Tds currently forecast in the lower 60s, heat indices would be near the air temps, keeping heat advisory potential low and sparse across NE NJ and possibly Lower Hudson Valley and portions of NYC. Elsewhere, temps well into the 80s likely for much of the rest of the area, with upper 70s/lower 80s for immediate southern and eastern coastal communities.

Potential for late Tuesday isolated tstm activity, mainly N&W of NYC, with approach of pre-frontal/thermal trough and weak vorticity lobes rounding the ridge. Low and sparse severe potential in a weak shear/marginally unstable airmass. Global model guidance for midweek continues to show a break down of the upper-level ridge in response to a closed upper-low traversing Canada. Better chance for scattered thunderstorms and isolated severe potential Wed aft/eve with falling heights, approaching pre-frontal trough/cold front, and likely better deep layer shear. This better potential indicated by CSU-MLP as well.


KEY MESSAGE 2
There are cold water safety concerns this weekend as water temperatures remain in the lower 50s. The cold water temperatures can quickly cause hypothermia and physical incapacitation to anyone suddenly immersed in the water. Anyone going out on small boats, canoes or kayaks should plan accordingly and use extreme caution to avoid this threat.

AVIATION /19Z FRIDAY THROUGH WEDNESDAY/
An upper level low departs to the NE while high pressure builds in from the west.

VFR conditions are expected through the TAF period. Some brief MVFR cigs are still possible for KGON as showers associated with departing upper low move through , but with the upper low departing, chances are decreasing.

Winds will be from the northwest today, 10-15 kt with some gusts to 20 kt or so. Sea breeze is trying to make its way through KBDR, but may push back south later this afternoon as the NW flow strengthens a bit, so have TEMPO group for S winds there through 20Z. Otherwise, peak gusts of 25 to 30 kt are possible, especially for KEWR. Gusts may be occasional at times.
Winds this evening diminish and become light and variable overnight. Winds Saturday morning will become south or southwesterly at 5 to 10 kt, increasing to 10 to 15 kt by mid morning with gusts 20 to 25 kt.

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

Gusts may be occasional today. A few gusts may be slightly higher than forecast.

OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY

Saturday: VFR. S-SW wind gusts 15-20 kt with gusts 20 to 25 kt in the afternoon and early evening.

Sunday: VFR. SW winds 5-10kt.

Monday: VFR. SE winds 5-10kt.

Tuesday: VFR. S-SW wind gusts 15-20 kt afternoon and early evening.

Wednesday: VFR becoming MVFR or lower in any showers and isolated thunderstorms in the afternoon. S to SW winds 10 to 15 kt, becoming WSW by late afternoon. Gusts 15 to 20 kt.

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

MARINE
SE swell from low pressure heading up into the Canadian Maritime will continue SCA seas across the ocean waters into the first half of tonight. The respite will be short-lived, as high pressure quickly builds across the waters late tonight into Saturday morning, then to the east.

A strengthening southerly flow is likely to bring a return to SCA conditions on the ocean late Saturday afternoon/early evening. as well as 25 kt gusts in Lower NY Harbor and south shore bays of W LI. Winds will gradually subside the second half of Saturday night into Sunday. However, ocean seas could linger around 5 ft on the ocean waters for much of Sunday with residual S swell.

There are cold water safety concerns this weekend as water temperatures remain in the lower 50s. The cold water temperatures can quickly cause hypothermia and physical incapacitation to anyone suddenly immersed in the water. Anyone going out on small boats, canoes or kayaks should plan accordingly and use extreme caution to avoid this threat.

Sub-SCA conditions are anticipated Sunday night through Monday night as flow temporarily weakens under high pressure. SCA conditions likely redevelop on the ocean water Tue into Tue night with strengthening SW flow, potentially for all waters by Wednesday.

OKX WATCHES/WARNINGS/ADVISORIES
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 2 PM to 11 PM EDT Saturday for ANZ338-345.
Small Craft Advisory until 6 AM EDT Saturday for ANZ350-353- 355.
Small Craft Advisory from 2 PM Saturday to 8 PM EDT Sunday for ANZ350-353-355.