Ansonia, Connecticut 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

251
FXUS61 KOKX 130147
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
947 PM EDT Sat Sep 12 2026

.WHAT HAS CHANGED...
No significant changes at this time.

&&

.KEY MESSAGES...
1) Widespread showers and a few thunderstorms ahead of an
approaching a warm front will move in late tonight into the
morning hours. Rainfall will be heavy at times with the potential
for isolated to scattered flash floods. A Flood Watch remains
in effect for portions of the area late tonight into early
afternoon.

2) Dry and near seasonable temperatures through mid next week.

&&

.DISCUSSION...
.KEY MESSAGE 1...
Early tomorrow morning into midday, we`re expecting a period of
showers with the potential of heavy downpours, a few
thunderstorms, and isolated to scattered flash flooding,
potentially into early Sunday afternoon out east.

A Flood Watch has been issued for NE NJ, NYC metro, and S
Westchester 4 am through 12 pm Sunday. A Flood Watch has also been
issued for Long Island, New London, Middlesex, New Haven and
southern Fairfield 6 am through 2 pm Sunday.

A southern stream shortwave passing over the area late tonight into
midday Sunday will tap into a tropical airmass (can see this plume
of moisture on GOES-EAST Water Vapor over the southeast) with PWATs
increasing to 2-2.5" by early Sunday morning. For reference, 2.03"
PWATs is the max moving average this time of year. A warm front will
also approach the area and potentially set up somewhere over the
coast/Long Island on Sunday morning. A weak wave of low pressure may
also track along the warm front, as indicated by many 12Z CAMs.
These ingredients will lead to showers with heavy downpours and a
few thunderstorms early Sunday morning into midday Sunday.

Much of tonight will be dry, but by daybreak, showers will begin to
overspread the area from west to east, mainly after 4 am. The latest
high-resolution modeling is showing the potential for enhancement of
the showers along the warm front Sunday morning. This is still a bit
difficult to resolve given the sensitivity of the exact location of
the warm front by Sunday morning, but it appears to lie over LOng
Island and S CT Sunday morning. It is promising that both the 12Z
HREF members and 12Z REFS members have been consistent from
their earlier 00Z cycles. This increases our forecast
confidence. The only real change is slightly slower onset
timing. There may also be some added lift aloft from a passing
jet streak over northern New England. Model soundings show a
deep warm cloud layer (14-15 kft) that can support efficient
warm rain processes. Model soundings also indicate slow 10-15 kt
Corfidi Upshear vectors, indicating good backbuilding potential
of showers/thunderstorms.

Given the slightly later onset timing from the previous forecast,
instability may be high enough to support more thunderstorms Sunday
morning. The best chances for these will be across Long Island and
coastal Connecticut where 12Z CAMs show MLCAPE getting around 500-
1,000 J/kg due to the warm front advancing north of these areas. Sfc-
500mb Bulk Shear values 35-45 kts and updraft helicity values 100-
150 m2/s2 in some CAMs is adequate. Lapse rates aren`t there, but
with a warm frontal boundary lingering nearby with model soundings
showing some speed and directional shear, an isolated tornado or
waterspouts along coastal areas can not be ruled out. However, low-
level flow is quite weak, so it is not a major concern.

The 12Z HREF has a probability of 3"/3hr rates across Long Island
and coastal CT at 30%. This same area has a 40-50% probability from
the 12Z REFS. WPC`s Urban Rain Rate Dashboard (URRD) brings the
highest 3"/3hr probs to these areas at 60-70%, and also includes NYC
in the highest probabilities. WPC`s URRD also has 30-40% probs for
3"/hr, which could be quite significant if it transpires. Based on
the timing of the probs, the greatest risk window for flash flooding
will be 6am (west) to 1pm (east).

The deep moisture and lift push east of the area around midday
Sunday. The heaviest rain should push east of the NYC metro shortly
after 10am, but could linger a few hours afternoon 12pm close
to farther east across Long Island and southern Connecticut.

Average rainfall amounts from NYC to SE CT range from 2 to 3.5
inches. Areas north and west of these spots closer to 1 to 2 inches
of rainfall. NYC, Long Island, coastal Connecticut could see
isolated higher totals of 5 to 7 inches.

A trailing cold front will move through Sunday evening with a
chance for isolated to scattered showers. These are not expected
to bring additional flooding and will mainly be brief, should
they occur.

.KEY MESSAGE 2...
Canadian high pressure builds in for early next week. Temperatures
start the week slightly below normal, but should trend towards
normal by Wednesday. Humidity levels will also remain low Monday and
Tuesday before starting to trend up mid week. A cold front may press
down on the area late in the week, but overall limited chances for
precip till late week.

&&

.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
An warm front approaching from the southwest tonight will bring
widespread showers and a few thunderstorms into the area toward
daybreak Sunday. The rain will exit from west to during the
late morning into the early afternoon hours.

Ceilings will lower to IFR, possibly low LIFR, from about 09z to
12Z. Rain will overspread the area from SW to NE, about 1-3
hours prior to the lowest conditions. Improvement expected for
NYC terminals and Lower Hudson Valley terminals from 15Z to
18Z, but will be several hours slower for the eastern terminals.
VFR expected to develop in the afternoon for all but KGON
(which may be closer to early evening (22Z).

The wind forecast has quite a bit of uncertainty after 12Z as
a warm front and frontal wave move across the area. Before then
though, SE winds less than 10 kt will back to the E/SE
overnight. Winds could vary anywhere from W/SW to E/NE across
the area behind the frontal wave and warm front Sunday, with
most locations becoming W/SW by late afternoon. Winds forecast
for this time is low confidence.

 ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments likely late tonight into the morning for timing of
heavy showers/thunderstorms and corresponding flight categories.

Low chance of southerly wind shear up to 2kft in the morning.

Wind forecast late morning into the afternoon is low confidence,
but generally less than 10 kt. Winds may be highly variable at
times. Even a chance of afternoon seabreeze development.

.OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY...

Sunday Night: VFR.

Monday: VFR. Northerly wind gusts 15-20 kt day into early evening.

Tuesday through Thursday: VFR.

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

&&

.MARINE...
Relatively weak pressure gradient will lead to conditions below SCA
levels through the middle of next week.

Rip Currents... A moderate risk of rip current development is
expected for both Sunday and Monday.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch from 6 AM EDT Sunday through Sunday morning for
     CTZ006.
     Flood Watch from 6 AM EDT Sunday through Sunday afternoon for
     CTZ007>012.
NY...Flood Watch from 6 AM EDT Sunday through Sunday afternoon for
     NYZ078>081-177-179.
     Flood Watch from 4 AM EDT Sunday through Sunday morning for
     NYZ071>075-176-178.
NJ...Flood Watch from 4 AM EDT Sunday through Sunday morning for
     NJZ002-004-006-103>108.
MARINE...None.

$$

DISCUSSION...BR
AVIATION...DW
MARINE...BR