discussion on 2024-03-06

000
FXUS61 KOKX 061642
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1142 AM EST Wed Mar 6 2024

.SYNOPSIS...
A frontal system and associated low pressure moves through later
today and tonight. The low will linger just east of the area through
Thursday night. High pressure will briefly nudge down from the north
on Friday. Another storm system will impact the region late Saturday
into Sunday. High pressure slowly builds back early next week.

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --Minor changes were made to temperatures in this update to
account for cooler temps, mainly on Long Island. The POPs are
still timed out well, with precip beginning in parts of the
area, shortly. The latest 12Z guidance shows an eastward shift
in some of the heaviest precip with rates of 1"/hr looking less
likely but still possible this evening and tonight for far
eastern areas. More details to come with the full update. For
now, all else remains on track.

A closed mid level low swings up from the south for the
afternoon and into this evening. The next slug of higher PWATs
/ moisture pushing up from the south for the afternoon and
evening. Rain should break out mostly from the S and SW, to the
N and NE through the afternoon, with far No. CT zones seeing the
rain very late in the day. Looking at the latest HREF PMM rain
amounts and rates look rather impressive where the moisture /
heavy rain axis can set up. Other than the ECMWF, the other
global guidance by and large has the higher IVT and PWATs values
perhaps being just a bit further to the east compared to the
higher majority of the higher resolution HREF members. The ECMWF
and NAEFS Situational Awareness Tables (ESATs) have 3 to 4
standardized anomalies with respect to the moisture plume moving
into the area. This is based on the climatology for the time of
year, and March is not typically a favored time of year for
impactful heavy rain. However the higher resolution guidance
cannot be dismissed, thus continuing with the Flood Watch for
the area. There still remains questions with the degree of
instability, however there should be enough warm rain processes
to drive rain rates of up to a half inch to one inch per hour in
the heaviest rain. The best chance of this occurring will be
towards 22z through about 06 to 08z across far E and NE
sections. The guidance does not appear to have the rain train
for long over the same areas, and it does move out quickly with
most of the guidance. Current consensus thinking with respect to
the various NWP points to a slug of 4 to 6 hours of moderate to
heavy rain. The relatively bigger concern is for eastern and
northeastern portions of the CWA from Central LI, N and NE into
Central and Eastern CT. The duration of heavy rainfall could be
a couple of hours longer, perhaps closer to 6 hours and would
result in locally higher amounts of 3 to 4 inches. Otherwise,
most rainfall totals will fall in the 1 to 3 inch range.
Antecedent conditions remain rather saturated from previous
rainfall, with antecedent conditions only worsening / getting
more saturated going forward in time with each subsequent rain
event. Thus WPC continues with the marginal to slight risk
across our area today and tonight, with the slight risk portion
expanded slightly to the west over the past couple of excessive
rainfall product iterations. With respect to the best thermal
forcing driven by the LLJ of around 40 kts at 850 mb, it appears
to be further east over the less flood prone areas. However the
western edge of the heavy rain axis will be right around the
NYC metro and portions of NE NJ and the eastern portion of the
Lower Hudson Valley. The HREF PMM appears more bullish on this
potential, but may be a bit overdone with respect to the heavy
rainfall duration across the area by a couple of hours.
Temperatures will run well above normal today with mainly 50s
region wide despite the clouds and the onshore flow.

The lower level jet and better mid level forcing gets further east
and north later tonight and into early Thursday morning. Look for
the rain to taper by the late evening, probably just before midnight
further west, but to the far east and northeast closer to 8-9z.
Temperatures will average around 10 degrees above normal, perhaps up
to 15 degrees in some locations tonight.-- End Changed Discussion --

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
On Thursday look for a purely stratiform rain with the winds having
more of a northerly component as low pressure attempts to redevelop
just to the south and southeast. Rainfall on Thursday will be on the
lighter side, and there is the chance that rain may completely shut
off for western areas late in the day. Have gone with consensus PoPs
on Thursday into Thursday night with the relatively higher PoPs
further east, especially earlier on. Temperatures will continue to
average above normal despite a good deal of clouds with mainly lower
and middle 50s for daytime maxes. For Thursday night the clouds
break up late in the evening, with clearing from west to east later
at night with a drier north breeze. Cooler air does arrive with
temperatures still a few degrees above average, but noticeably cooler
late at night.

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Confidence continues to increase in unsettled weather returning for
the upcoming weekend. The weather pattern looks quieter for the
first half of next week.

*Key Points*

*Low pressure slowly departs to the east Friday with dry conditions
through Saturday morning.

*The next storm system approaches Saturday, impacting the area late
in the day through Sunday.

*Another period of moderate to locally heavy rainfall is possible
with the weekend system, but specific impacts are unknown at this
time and may be related to where the heaviest rain falls with the
Wednesday/Wednesday night system.

*Dry weather returns the first half of next week.

Broad low pressure will be situated off the east coast Thursday,
with the associated upper level trough over the northeast.
There is a good agreement among the modeling that the trough axis
will be slow to depart to the east. While the deepest moisture
should be offshore, there will likely be some lingering lighter rain
in the morning, which becomes scattered in the afternoon. Some of
the latest guidance is hinting at a mostly dry Thursday afternoon
with some lingering low clouds and a few sprinkles. Any impactful
rain with the mid week system is likely to occur through Wednesday
night and no additional significant rain is currently expected
Thursday.

A brief period of dry weather takes place Friday as a ridge returns
aloft and high pressure takes control at the surface. Expect a
mostly sunny day Friday. The ridge axis shifts east Friday night
into Saturday morning ahead of the next storm system. Developing low
pressure across the Plains on Friday shifts towards the Great Lakes
Friday night through Saturday. The low then tracks towards southeast
Canada Saturday night with redevelopment taking place over New
England Sunday morning. The low continues to deepen as it occludes
near Maine later Sunday into Sunday night.

The parent low passing well to our NW and retreating high pressure
support this event being a rain event. The latest model consensus
brings in the steadiest rain Saturday evening through Sunday
morning. Moderate to locally heavy rain could occur with this system
with another 1-2 inches of rain possible. These details are still of
lower confidence given that the event is several days away. It is
also important to note that where the heaviest rain occurs with
today / tonight`s system may result in hydrologic impacts with the
weekend system. The system departs Sunday with the associated upper
low passing through Sunday into into early Monday. There could be
some lingering precip Sunday night with the upper low with a low
potential of a rain/snow mix well inland.

High pressure builds in Monday into Tuesday and will be in control
into the middle of next week. Temperatures will be above normal
Friday in the upper 40s and lower 50s. Near normal highs in the
middle to upper 40s are expected Saturday with highs to slightly
above normal readings Sunday. Temperatures Monday may be below
normal in the lower to middle 40s before a warming trend Tuesday
into Wednesday.

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --Low pressure approaches from the south today, passing over the
area terminals this evening and overnight.

IFR or lower with little improvement today. Terminals likely
decline to LIFR or lower this afternoon as rain moves into the
area after 18Z.

Period of moderate to locally heavy rainfall this evening into the
first half of tonight. Likely a 3-5 hour window of this,
generally between 22z-03z for the NYC terminals, but could
linger several hours thereafter. After 06z, rain will start to
taper off from west to east. Some slow improvement is expected
toward 12z Thursday, with MVFR cigs possible. Return to VFR late
Thu AM or early afternoon.

Light and variable winds this morning take on more of a E to NE
direction as the low approaches from the south. As the low passes
over the area, winds become more northerly tonight. Winds remain
around or less than 10kt through much of the TAF period.

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

Amendments likely for changing flight categories.

OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...

Thursday: MVFR or lower earlier, improving to VFR by afternoon.
Winds N to NE G20- 25kt.

Friday: VFR.

Saturday: MVFR with a chance of rain early, then rain likely late
day and at night.

Sunday: MVFR with rain in the morning. Possibly VFR in the afternoon
with a chance of rain.

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

.MARINE...
Small craft conditions will prevail on the ocean waters with mainly
4 to 6 ft seas today. Seas will climb higher tonight into Thursday.
Small craft gusts will become increasingly likely into Thursday
morning on the non-ocean waters, and could linger into Thursday
night, especially further east. SCA conditions continue on the ocean
Friday. Winds should largely fall below SCA levels Friday except
well east of Moriches Inlet. Seas will remain elevated. A brief
period of sub-SCA conditions are expected Friday night before the
next storm system this weekend. SCA conditions should return late
Saturday and especially Saturday night and Sunday.

.HYDROLOGY...
WPC maintains a slight to marginal risk of excessive rainfall today
and tonight. A flood watch remains in effect. Widespread minor
flooding is expected, with some river flooding as well as more
significant flash flooding possible.

An additional 1 to 2 inches of rain could fall with the storm system
this weekend. Impacts with this event are still somewhat uncertain
as it will depend on where the heaviest rain falls with the
Wednesday/Wednesday night system.

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --CT...Flood Watch through late tonight for CTZ005>012.
NY...Flood Watch through late tonight for NYZ068>075-078>081-
176>179.
NJ...Flood Watch through late tonight for NJZ002-004-006-103>108.
MARINE...Dense Fog Advisory until 1 PM EST this afternoon for ANZ331-
332-335-338-340-345-350-353-355.
Small Craft Advisory from 10 AM Thursday to midnight EST
Thursday night for ANZ331-335-338-340-345.
Small Craft Advisory from 10 AM Thursday to 6 AM EST Friday
for ANZ332.
Small Craft Advisory until 6 AM EST Friday for ANZ350-353-355.-- End Changed Discussion --

SYNOPSIS...JE/DS
NEAR TERM...JE/BR
SHORT TERM...JE
LONG TERM...DS
AVIATION...DR
MARINE...JE/DS
HYDROLOGY...JE/DS