Marine Weather and Tide Forecast for Old Greenwich, CT

KEY MESSAGES
1. Unseasonably warm with temperatures 10-20 degrees above normal Monday.

2. Forecast remains on track for a significant warmup next week, peaking during the Wednesday into Thursday time frame.

DISCUSSION

KEY MESSAGE 1
High pressure moving off the northeast coast into Monday will allow for a return flow to set up into Monday, as upper ridging moves into the northeast and mid Atlantic coast. Some weak energy rotating over the top of the ridge this evening into late tonight may produce a few showers, mainly across southeastern Connecticut. Also, a warm front will be approaching to the west through tonight as the surface high moves offshore.
This front quickly moves north of the area early Monday morning with the onset of daytime heating. Warm advection and heating during Monday will boost temperatures to well above normal with inland temperatures in the mid 70s to around 80 degrees, nearly 20 degrees above normal. The southerly flow will keep temperatures cooler, but still above normal by around 10 degrees. If the flow becomes more southwest to west/southwest coastal areas could see highs a few degrees warmer than currently forecast.


KEY MESSAGE 2
There is medium to high confidence of record warmth across the area on Wednesday with unseasonably warm temperatures into next weekend. A broad upper ridge centered over the Southeast into the eastern Gulf of America and a confluent flow to the north will produce a warm, deep-layeed WSW flow. High temperatures Wednesday and Thursday will average 20 to almost 30 degrees above normal. Thursday is likely to fall short of record highs as they are quite high due to the heat wave of 2002. Several climate sites from April 16-18, 2002, reached 90 or higher for 3 consecutive days. Don't see that happening at this time. Also to note, there is very little spread in the box and whisker plots from Tuesday to Thursday, only a few degrees between the 25th and 75th percentiles. Thus, largely stayed with the NBM during this time with a minor bump up Wednesday and Thursday.
Additionally, there is the potential for several days of record high minimum temperatures.

Where this forecast could go wrong is with the proximity of a frontal boundary to the north during mid week. 12Z GFS looks like it generates enough convection to the north sending the boundary back into the area Thursday. THe GEFS and AI-GFS are similar. The ECMWF and Canadian keep it north and very warm.
Have to see where this goes in subsequent runs.

A cold front will pass through on Friday with a gradual cool down through the weekend. However, there is some uncertainty as to how quickly the boundary lifts back to the north ahead of another frontal system moving into the area next Sunday. There is about 5 to 10 degrees of spread temperatures in the NBM between the 25th and 75th percentiles.

As for rain chances, there is a chance of late day convection coming around the upper ridge Tuesday through Thursday and with a cold front next Sunday.

AVIATION /00Z MONDAY THROUGH FRIDAY/
High pressure continues to slide offshore this evening. A warm front lifts north of the terminals early Monday morning. Low pressure passes to the north on Monday.

VFR for much of the night. Some MVFR and possibly IFR conditions will be possible early Monday morning as the warm front passes over the region. Some locations east of NYC could see the MVFR or lower cigs, specifically KGON, linger into the afternoon.
Will keep the TAFs dry for now, but can not rule out a chance for a light shower in the afternoon. The best chances will be north of the NYC terminals.

SE-S winds generally remain below 10kt tonight. Winds become SW 10-15KT G20-25KT early, then WSW 15-20KT G25-30KT late. Winds are expected to diminish after 00z Tuesday.

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

Uncertainty with just how much if any MVFR or even IFR cigs develop over the terminals.

OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY

Tuesday through Friday: VFR. SLight chances of afternoon and evening showers and thunderstorms each day, low-end chance inland Wed night, with MVFR possible.

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

MARINE
Winds and seas remain below advisory levels on all the forecast waters late Sunday afternoon into early Monday morning.
However, with a strengthening southern flow ocean seas may build to 5 feet across the outer waters by early Monday morning.
With southerly gusts near 25 kt across the Long Island south shore bays during Monday have added that zone to the advisory.
Wind gusts across the eastern Long Island Sound zone may at times be near 25 kt, however, with low confidence in reaching, and being more occasional, have not included in an advisory.
Otherwise with gusts and seas at SCA levels on the ocean waters Monday night into Tuesday, have extended the advisory, mainly for the eastern ocean zone, into Tuesday morning as the flow becomes more SW and slowly diminishes as seas slowly subside.
For the Wednesday through Friday timeframe, a mainly southerly flow looks weak enough for sub-SCA conditions with seas on the ocean 3 to 4 ft. A weak cold front passes through on Friday.

CLIMATE
Daily record high temperatures that could be reached:

Wed April 15: KEWR: 88/1960 KBDR: 81/1960 KNYC: 87/1941 KLGA: 86/1941 KJFK: 80/2006 KISP: 78/2024

OKX WATCHES/WARNINGS/ADVISORIES
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 8 AM to 6 PM EDT Monday for ANZ345.
Small Craft Advisory from 8 AM Monday to 11 AM EDT Tuesday for ANZ350.
Small Craft Advisory from 8 AM Monday to 6 AM EDT Tuesday for ANZ353.
Small Craft Advisory from 8 AM Monday to 2 AM EDT Tuesday for ANZ355.