Discussion on 2023-04-03

000
FXUS61 KOKX 031444
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1044 AM EDT Mon Apr 3 2023

.SYNOPSIS...
-- Changed Discussion --High pressure shifts into the Western Atlantic today, while a
frontal boundary meanders just north of the area. The front may
sink south through the region Tuesday night, before returning
north as a warm front later Wednesday. The attendant cold front
moves through the region Thursday. High pressure then dominates
Friday into the weekend.-- End Changed Discussion --

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --Southerly flow is beginning to pick up as of 14z now that
surface high pressure has shifted out into the Atlantic.
Abundant sunshine prevails this afternoon, with some high clouds
developing late today and this evening from a disturbance
passing well to the south through the Carolinas. Only minor
adjustments made in the near term to account for trends with
observations, otherwise, forecast remains on track and previous
discussion follows.

Increasing clouds and more southerly flow is expected today as
the synoptic return more southerly to southwesterly flow
develops. There will likely be sea breeze enhancements along the
coast, especially with the Ambrose Jet this afternoon.
Therefore, expecting gusty winds this afternoon along the
coastline.

Model 850mb temperatures will be on an increasing trend this
afternoon and this more southerly synoptic flow will allow for
this warmer air to advect across the region. Model 850mb
temperatures indicate a range of near 3 to 6 degrees C going
into early this evening. With forecast soundings showing
adiabatic vertical mixing up to near 900 to 850mb away from the
coast, and more shallow, only up to near 950mb along the coast,
this will further convey a spatial temperature gradient that
will also show the marine influence of the more southerly
surface flow.

NBM50th percentile used for the max temperature forecast,
raised one degree across Northeast NJ, Lower Hudson Valley, and
Southwest CT where temperatures could trend higher with
subsequent forecast. Then blended this new forecast with the
previous forecast. Want to exhibit a more vast range between the
eastern and western sections of the forecast region to show
that maritime influence on the temperature gradient.-- End Changed Discussion --

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
-- Changed Discussion --For tonight, with a cold front approaching from the north and
west, clouds will continue to increase. Southerly flow will
remain steady along the coast and will be less farther inland.
Winds will weaken across the Lower Hudson Valley and Southern CT
earlier in the night. Warmer than normal temperatures are
expected for the forecast lows. Used a combination of NBM the
percentile (75 percent) and consensus of raw model temperature
(25 percent) for the low temperature forecast as it exhibits a
less vast range of temperatures across the region.

Late tonight as the cold front nears the northernmost portions
of the forecast region, there could be a few rain showers as
suggested by some of the mesoscale models and their reflectivity
fields. The parent low attached to the front will be filling in
and weakening so the front will weaken and slow down. The
pressure gradient will be weakening as well and even the
coastline southerly flow will lessen overnight into early
Tuesday morning.

On Tuesday, the front that is close to the northern parts of
the region weakens and eventually dissipates. The surface flow
remains southeasterly with more southerly flow along the coast.
However, the wind speeds will remain light and under 10 kts.

For Tuesday, the 850mb temperature increase to near 7 to 9
degrees C by early evening, which will be a few degrees warmer
than the previous day. Temperatures at the surface likewise are
expected to trend several degrees warmer than the previous day.
However, with limited vertical mixing and clouds lingering
around, did not go as high as NBM for the max temperatures.
Instead, blended NBM with consensus of MOS and then blended that
with previous forecast.

Flow becomes more easterly Tuesday night as high pressure
builds into Southeast Canada and into Northern New England as
well as Nova Scotia. Models are indicating the weak frontal
boundary to become a stationary front associated with the next
low pressure wave moving near the Great Lakes. Moisture
convergence increases along and near the front in the low
levels. Would expect widespread stratus to develop and chances
for rain to increase. This will keep low temperatures warmer
and less spatial spread across the area with a blend of raw
consensus and NBM the percentile for forecast lows.

On Wednesday, the front remains nearly stationary but easterly
flow increases in the area. The abundance of clouds and the rain
in the area will keep cooler temperatures compared to the
previous day. The front Wednesday becomes a warm front and moves
north of the area Wednesday into Wednesday night. The flow
becomes more southerly and further increases Wednesday night.
Rain chances continue Wednesday night.

Highs forecast Wednesday and lows forecast for Wednesday night
both utilized a blend of NBM and consensus of raw data.-- End Changed Discussion --

.LONG TERM /THURSDAY THROUGH SUNDAY/...
No significant changes made to the long term Thursday through the
upcoming weekend.

The pattern on Thursday will feature a strong ridge departing the
eastern seaboard with deep upper level low/trough tracking across
southeastern Canada. A surface cold front will likely be situated
just NW of the region Thursday morning. The modeling is in
relatively good agreement on the cold front moving across the area
in the afternoon and early evening. Large scale support is limited
with the upper low/trough well north of the area. Convergence along
the front appears to be the main focus for shower development
especially in the afternoon/early evening. The region will be in the
warm sector, but as is usually the case, there are uncertainties
regarding the amount of instability. The current consensus of the
guidance supports the addition of a slight chance of thunder from
around the NYC metro into NE NJ and the Lower Hudson Valley. While
surface winds look to be SSW-SW, the flow off the colder ocean
should limit instability further east. Shear is not as strong as the
last event this past Saturday, but 40 to 55 kt of middle level flow
could help with storm organization. Will have to monitor trends with
instability over the next few days to see if a more organized line
of convection is possible. Otherwise, highs on Thursday should reach
the lower to potentially middle 70s along and west of the Hudson
River. Further east, highs will be held down from maritime influence
with readings in the upper 50s to middle 60s.

The cold front moves offshore Thursday night with high pressure
building in from the midwest through Friday. The high should
dominate the surface pattern for the upcoming weekend with dry
conditions as well. Temperatures Friday through the weekend will be
closer to seasonable levels for this time of year.

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --High pressure shifts offshore through this evening. Low pressure
passes well north of the area, sending a cold front towards the
region tonight.

VFR through much of the TAF period. MVFR ceilings are possible early
Tuesday morning well NW of NYC metro terminals. The chance for MVFR
ceilings is lower closer to the coast.

Winds S-SE this morning, increasing to around 12-17kt with
gusts 20-25 kt in the afternoon. Winds will then decrease 00-02z
Tuesday and settle below 10 kt overnight. Winds should become
light and variable early Tuesday morning.

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

Onset time of gusts may be off by 1-2 hours.

Sea breeze enhancement is likely at KJFK late afternoon, with
potential for sustained winds and gusts a few kt higher.

...OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...

Tuesday-Tuesday Night: MVFR possible early morning, otherwise VFR.
IFR develops Tuesday night with a chance of light rain or drizzle.

Wednesday-Wednesday Night: IFR likely with a chance of showers.

Thursday: MVFR possible. Showers likely in the afternoon/evening.
Slight chance of a thunderstorm NYC terminals on NW in the
afternoon/evening. SW gusts 15-25 kt Thursday, becoming W-NW at
night.

Friday: VFR. W-NW G20-25kt.

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

.MARINE...
-- Changed Discussion --High pressure shifts offshore today as a frontal boundary
meanders just north of the waters through Tuesday.

SCA conds expected for all waters this afternoon into early
evening, lingering for ocean tonight. Gusts 25-30 kt can be
expected everywhere during this time, with seas building to
around 5 ft on the ocean. Sub-SCA conditions then Tuesday
through Wednesday, with SCA conditions developing again
Wednesday night. The ocean and wind gust forecast SCA levels for
ocean, just wind gust forecast SCA level for non- ocean waters.

Modest S-SW flow ahead of a cold front Thursday will bring the
continuation of SCA conditions on the ocean and potentially the LI
Bays and Eastern Sound. Winds should fall below SCA levels Thursday
night behind the cold front passage, but elevated seas may linger
into the first half of the night. NW winds then pick up on Friday
with high pressure building in from the midwest.
Winds may reach marginal SCA levels.-- End Changed Discussion --

.HYDROLOGY...
No hydrologic concerns are expected through next weekend.

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 2 PM this afternoon to 9 PM EDT this
evening for ANZ331-332-335-338-340-345.
Small Craft Advisory until 6 AM EDT Tuesday for ANZ350-353-355.-- End Changed Discussion --

$$
SYNOPSIS...JM/DR/DS
NEAR TERM...JM/DR
SHORT TERM...JM
LONG TERM...DS
AVIATION...MET
MARINE...JM/DS
HYDROLOGY...DS