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439
FXUS61 KOKX 131814
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
214 PM EDT Thu Jun 13 2024

.SYNOPSIS...
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High pressure moves farther out into the Atlantic through
tonight. A cold front approaches Friday and moves across Friday
night. High pressure returns for the weekend before sliding
offshore early next week.
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&&

.NEAR TERM /UNTIL 8 AM FRIDAY MORNING/...
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Forecast remains on track. Temperatures and dewpoints still
have good agreement last few hours comparing forecast with
observed values. Some cumulus development has occurred with
scattered to broken cirrus moving across the region.

Still have some sea breeze enhancement expected for the
afternoon into early this evening. Gusty southerly flow can be
expected along the coast but will be partially limited as warmer
air moves in aloft.

High pressure will further weaken tonight and move farther out
east into the Atlantic. After the decrease of the cumulus and
overall mostly clear conditions to start tonight, expecting an
increase in clouds from west to east overnight.

With some low to mid level Q vector convergence noted more so
by the GFS with this not indicated as much with the NAM, have a
slight to low end chance of showers late overnight into early
Friday morning for parts of the southern coastlines covering the
area from coastal CT through coastal NE NJ, NYC and Long Island.
In the mid levels, the models do convey weak positive vorticity
advection on the backside of the mid level ridge traversing the
local region between 2AM and 8AM Friday.

With the southerly flow continuing along the coast and
increasing clouds late, went with more mild low temperatures.
Lows used a combination of NBM and consensus of all guidance,
with values mainly in the mid 60s to near 70.
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&&

.SHORT TERM /8 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
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Even warmer with a subtle climb in humidity as a S to SW flow
increases overall as a cold front approaches from the west.
Expect lots of sunshine through the early afternoon, with clouds
increasing from west to east with the approach of a cold front.
Temperatures are expected to reach the upper 80s to 90 for the
NE NJ metro, with mainly 80s elsewhere, and middle and upper 70s
across far eastern coastal sections. Convection ahead of the
cold front is expected to initiate towards 18 to 20z for the
northwestern portions of the CWA, with the activity moving ESE
through the late afternoon and evening. SPC has placed the area
in a marginal to slight risk of severe thunderstorms, with the
slight risk roughly for the western half of the CWA. The main
threat with any storms at this time appears to be gusty to
damaging wind gusts in any stronger storms. Storm mode appears
to be multi-cell clusters with perhaps the storms becoming more
of a broken organized line as it gets closer to the metro during
the evening. MLCAPE values are expected to exceed 1000 J/kg for
far western areas, with bulk shear values in the 35 kt vicinity
as this has the chance to be the first widespread thunderstorm
activity of the season for a good portion of the CWA. A general
weakening trend in any storms is expected as the storms
encounter more of a marine environment as they move across the
eastern third of the CWA.

The showers and storms should slide to the east by midnight for far
eastern sections. A Drier NW flow moves in quickly in the wake of
the FROPA, with noticeably lower humidity into Sat AM with clearing
skies.
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&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Surface high pressure builds in from the NW behind the exiting cold
front on Saturday, centering itself over the area on Sunday as an
upper-level ridge begins to build into the area. This ridge remains
over the Northeast on Monday before amplifying Tuesday into
Wednesday, remaining highly amplified into Thursday.

HEAT! That pretty much sums up the concerns for the long-term
forecast. Our first heat wave of the season could be a possibility
with multiple days expected to reach the mid-90s with upper-90s
possible. The hottest days are expected to be Tuesday through
Thursday. Heat index values are projected to be between 95 and 100
at their peak due to higher dewpoints being advected in from onshore
flow. This onshore flow, however, could lead to subtle relief for
Long Island and parts of coastal Connecticut where winds blowing in
from cooler ocean waters may allow their temperatures to be slightly
cooler than the rest of the CWA. Heat Advisories may need to be
issued as the event nears, if the forecast does not change too much.

850mb warm air advection starts aloft on Monday, but doesn`t really
become anomalously strong until Tuesday. Its important to note that
there is uncertainty with regards to the maximum temperatures. All
global model guidance agrees on a highly-amplified ridge over the
northeast with warm air advection aloft, but they still differ in
magnitude. Expect the forecasted temperatures to change somewhat
until the model guidance comes into better agreement. For now, went
with a blend of NBM deterministic and NBM 50th percentile. Even the
NBM 25th percentile was warmer than the deterministic NBM, so by
blending the two together, it has increased forecasted temperatures
next week.

A few weak shortwaves embedded within the longwave ridge on Sunday
and Monday will help forestall strong heat until Tuesday. The
shortwaves will increase cloud coverage somewhat and prevent the
ridge from amplifying until Tuesday. This will leave temperatures
near normal for the weekend and only slightly above average on
Monday.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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VFR through most of the TAF period.

A cold front approaches from the NW late Friday bringing
unsettled weather late Friday into early Saturday morning. Best
chance of TSRA 18-22z Friday KSWF and 20-00z Sat across city
terminals. Heavy rain and gusty winds possible in any TSTM
Friday.

S-SW Winds 10-15kt with gusts to 25kt at the coast continue
into early evening. Tonight, gusts diminish but winds are
expected to remain around 10 kt overnight into Friday morning.
Stronger winds possible in vicinity of stronger TSTMs Friday
afternoon and evening.

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

No unscheduled amendments likely through 18z Friday.

OUTLOOK FOR 18Z FRIDAY THROUGH MONDAY...

18z Friday: MVFR or lower possible in showers/tstms late
afternoon or evening.

Saturday through Monday: VFR.

Tuesday: VFR expected. CHC of MVFR in afternoon SHRA/TSTM mainly
NW of city terminals

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

.MARINE...
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More southerly flow this afternoon with gusts expected to 20-25
kt. The gusts will be occasional as warmer air moving in aloft
will limit mixing. So, do not have SCA for any of the forecast
waters as the 25 kt gusts are just expected to be occasional.
Seas on the ocean expected to remain below SCA thresholds and
well below SCA thresholds for non-ocean waters. Wind subside
tonight with wind gusts on Friday to near 20 kt. Winds subside
again Friday night with wind direction eventually becoming more
NW.

Sub small craft conditions then prevail through early next
week.
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&&

.HYDROLOGY...
Showers and thunderstorms are expected to bring a round of brief,
but locally heavy rain late Friday and Friday evening. Rainfall
amounts are expected to average from around a half inch to one inch.
Instantaneous rainfall rates will be rather high, but the storms are
expected to progress along. Therefore impacts will most likely be
limited to minor urban and poor drainage flooding due to the quick
movement of this system, with flash flooding appearing unlikely at
this time.

&&

.TIDES/COASTAL FLOODING...
There remains a moderate rip current risk this afternoon for the
ocean beaches, and a high risk for most ocean beaches Friday.
Eastern Suffolk beaches are expected to have a moderate rip current
risk on Friday.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$

SYNOPSIS...JE/BR
NEAR TERM...JM
SHORT TERM...JE
LONG TERM...BR
AVIATION...IRD
MARINE...JM/BR
HYDROLOGY...JE/BR
TIDES/COASTAL FLOODING...