discussion on 2023-05-11

000
FXUS61 KOKX 111947
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
347 PM EDT Thu May 11 2023

.SYNOPSIS...
-- Changed Discussion --High pressure builds to our south this evening moving offshore
tonight as a shortwave trough passes to our northeast. Weak low
pressure tracks through northern New England Friday into Friday
Night with a weak trailing front approaching and then
dissipating over the area. A stronger cold front approaches from
the north Friday night into Saturday with a weak wave of low
pressure approaching the local region from the west, as well. High
pressure builds in late Saturday through Sunday and weakens
Monday as a cold front approaches from the north. The front
moves through Tuesday into Tuesday night. High pressure returns
for Wednesday and Thursday.-- End Changed Discussion --

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --Surface high pressure remains to our south and west this afternoon
and evening as a mid-level shortwave trough located to our northeast
tracks close-by. This will provide enough lift for an increase in
cloud cover this evening, particularly for eastern Long Island and
SE Connecticut. Nearly all CAMS bring isolated to scattered showers
to eastern Massachusetts, but none make it to our area as the
shortwave is just too far away to bring any moisture. Cloud cover
may remain higher for eastern areas along the periphery of the
shortwave before its exit.

We`ll remain dry tonight as surface high pressure
maintains its influence and even builds slightly as the shortwave
exits to our east. This could lead to a clearing of any clouds in
the area. After looking at mid-level moisture, most deterministic
models bring higher 700 RH values on Friday morning from deeper
trough to our north which could lead to clouds building back in the
area early on Friday. This was shown in the forecast by taking a
blend between the deterministic NBM and the 90th percentile, as
cloud cover appeared a bit on the low side with only the
deterministic.

With cloud cover increasing again tomorrow morning, raditional
cooling will be limited, so this has been reflected in the grids by
mostly using NBM for temperatures, which seemed to fall in line
with my thinking quite nicely. I did blend some consensus MOS
for low temperatures, but even MOS guidance was not picking up
on radiational cooling. Overall temperatures will be warmer tonight
with more warm air advection occuring from light westerlies. Only
this afternoon and evenining differ on forecasted hourly temperatures.
Here I used a blend between the HRRR and NBM to better account for
the sea breeze circulation.-- End Changed Discussion --

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
-- Changed Discussion --A weak northern stream shortwave sinks southeast towards the region
late tonight and slides southeast Fri morning into early afternoon.
Weak shortwave ridging builds in Fri eve, before a strong northern
stream low pivots into northern New England and shearing
southern stream shortwave approaches Friday Night.

At the surface, a weak surface wave approaches northern New England
tonight, and slowly slides through Friday into Fri Night. Its
trailing weak cold front/trough approaches the area from the NW Fri
Am, and then stalls/dissipates overhead across the interior.

Continued WAA in WSW flow will have 850 hpa temps a couple of
degrees warmer than today, with continued deep mixing and ample
sunshine allowing for temps to rise well into the 80s away from the
south coasts. Gusty WSW flow will give way to afternoon seabreeze
development once again, capping temps in the upper 70s/lower 80s
(cooler along immediate south shorefront). Temps should stay below
records on Fri (upper 80s/lower 90s), but may get within a couple
degrees at LGA.

With shortwave aloft, and moisture pooling ahead of dissipating front,
CAMs/soundings indicate potential for an isolated shra/low topped
tstm developing off higher terrain in the afternoon. Localized
strong wind gusts with any convection would be primary threat with
dry mid-level and inverted V soundings.

Any convection dissipates early Fri eve in wake of shortwave, with
unseasonably mild conditions under continued waa sw flow and
increasing high/mid deck. Low temps generally in the 60s.-- End Changed Discussion --

.LONG TERM /SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --A cold front pushes south of the region during Saturday as a wave of
low pressure moves out of the Ohio Valley to the Delmarva. A slight
southward trend continues with the low and inland portions of the
forecast area will be on the northern periphery of the precipitation
shield, as there is little moisture of frontal lift along the cold
front. Any precipitation that occurs will be light, especially
inland as the lower levels will be rather dry across the area.
Removed the mention of thunder with little to no instability or
CAPE. With the slower movement of the front temperatures should be
well above normal, reaching into the upper 70s and lower 80s. Raised
temperatures, leaning toward the MOS guidance, as winds will
initially be more westerly.

High pressure builds in from the northwest Saturday night into the
beginning of next week. An upper low over eastern Canada sheers out
monday into Tuesday as surface high pressure weakens.
Meanwhile, low pressure moving out of the northern plains and into
the mid Atlantic Monday is suppressed farther to the south, and will
keep the area dry. Another cold front moves out of Canada Tuesday
and through the area Tuesday night. Once again there will be little
moisture or lift with the front, and at this time will have just
slight chance probabilities per the NBM. A cooler airmass moving
from central Canada will return temperatures to seasonal normal
levels for Wednesday and Thursday, after temperatures being above
Saturday through Tuesday.-- End Changed Discussion --

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --VFR as a broad area of high pressure remains over the area through
Friday. A surface trough lingers near the terminals into this
evening and then again on Friday afternoon.

W flow around 10-13 kt with gusts 17-20 kt possible this afternoon.
SSW-SW sea breezes are occurring at KJFK, KISP, KBDR, and KGON. Wind
speeds will weaken this evening with the flow W-SW around 5 kt at
NYC terminals overnight. Outlying terminals will go light and
variable.

Winds increase Friday morning, becoming 10-15 kt with gust up to 20
kt possible in the afternoon. Late morning-afternoon SW-S sea
breezes likely at coastal terminals.

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

A few gusts around 20 kt possible at KJFK through 00z.

Some variability in wind direction between 230-290 this afternoon at
KLGA and KEWR due to surface trough in the vicinity.

Low chance sea breeze makes it across KLGA early this evening.

...OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...

Friday Afternoon-Night...VFR.

Saturday...Chance of showers with MVFR possible.

Sunday-Tuesday...VFR.

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

.MARINE...
-- Changed Discussion --Sub SCA conditions continue through Friday night under a weak
pressure gradient. A brief period of marginal SCA gusts possible
nearshore Friday afternoon into early evening with enhanced sea
breeze development.

Winds and seas remain below SCA levels Saturday through Monday.
With an increasing southwest flow ahead of an approaching cold front
Monday night into Tuesday wind gusts will increase to near SCA
levels on the ocean waters and seas will build to near 5 feet,
especially on the waters east of Moriches Inlet.-- End Changed Discussion --

.HYDROLOGY...
No hydrologic impacts are expected through Wednesday of next
week.

.CLIMATE...
-- Changed Discussion --Record Maximum High Temperatures for Friday, May 12th
-----------------------------------------------------
Newark NJ..........92 (1959)
Bridgeport CT......88 (1991)
Central Park NY....93 (1881)
LaGuardia NY.......88 (1991,1948)
Kennedy NY.........89 (1991)
Islip NY...........87 (1991)

Record Maximum Low Temperatures for Saturday, May 13th
-----------------------------------------------------
Central Park........69 (1956)
LaGuardia...........67 (1956)
Kennedy.............64 (1991)
Islip...............60 (1991,1985,1975)
Newark..............68 (1985,1956)
Bridgeport..........59 (1985)-- End Changed Discussion --

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

$$
SYNOPSIS...BR/MET/NV
NEAR TERM...BR
SHORT TERM...NV
LONG TERM...MET
AVIATION...DS
MARINE...BR/MET/NV
HYDROLOGY...BR/MET/NV
CLIMATE...