579
FXUS61 KOKX 122146
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
546 PM EDT Wed Jun 12 2024
.SYNOPSIS...
Weak high pressure over the area tonight will shift offshore
Thursday into Thursday night. A cold front approaches from the
west on Friday, moving through Friday night. High pressure then
builds in from the Great Lakes this weekend, before sliding
offshore early next week.
&&
.NEAR TERM /UNTIL 7 AM THURSDAY MORNING/...
-- Changed Discussion --
A quiet evening ahead with decreasing cloud cover and weak high
pressure residing nearby. Forecast remains on track and
previous discussion follow.
Sea breeze circulation will weaken this evening. Winds overall
become lighter tonight. Not much in terms of cloud coverage is
expected. This will set up more efficient radiational cooling
within the valley and rural sections. Made these locations
slightly cooler than previously forecast. Lows forecast range
from the low to mid 50s in these valleys and outlying areas to
more in the upper 50s to mid 60s range for most locations
elsewhere.
Some patchy fog particularly within valleys and some rural
locations can be expected due to radiational cooling late
tonight towards early Thursday morning.-- End Changed Discussion --
&&
.SHORT TERM /7 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
The high pressure moves out into the Atlantic Thursday. The
synoptic pattern will favor the development of the Ambrose Jet
with southerly winds for SW Long Island increasing to around 15
kt with otherwise a southerly wind near 10 kt elsewhere within
the forecast region during the afternoon. It is expected to be a
mostly sunny day with high temperatures getting well into the
80s for a majority of the region.
Winds weaken with a weakening pressure gradient Thursday night.
Again not much in the way of cloud coverage is expected. Lows
will only be within the 60s with a warmer airmass moving into
the area. Not as much low level saturation is expected so did
not mention any fog in the forecast.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
**Key Points**
* Showers and thunderstorms are expected to move through the region
Friday afternoon and evening, with some potentially strong to
severe and capable of producing damaging winds and large hail.
* Heat builds early to mid next week and heat indices could exceed
100F at times, especially north and west of NYC.
An active start to the period with lowering heights as a trough digs
south out of Canada, and a shortwave swings east into the local area
on Friday. An associated cold front will advance toward the region
with it, passing through and offshore Friday night. Ahead of the
front, showers and thunderstorms are expected to develop in a warm,
moist air mass. Surface temperatures into the 80s during the
afternoon and dew pts in the mid to upper 60s should aid the
convective development, and BUFKIT soundings indicate CAPE
increasing across the interior to over 1000 J/kg by early afternoon.
SPC has areas north and west of NYC outlined in a slight risk,
indicative of the potential for scattered severe thunderstorms.
CSU`s machine learning output is in agreement with this assessment.
Timing of this threat looks to span from afternoon into the early
evening hours, earliest across the Lower Hudson Valley, and latest
along SE CT and eastern LI as the line advances south and east.
In addition to a threat for damaging winds and large hail with these
storms, increasing moisture will bring the risk of heavy downpours
with any storms. PWATs ahead of the front climb to as high as 2
inches, and with a warm cloud layer well above 10 kft, efficient
rain processes could aid in torrential downpour development. While
total QPF averages around a half an inch across the region with this
forecast, localized amounts could exceed an inch or two in a
relatively quick period of time, so rates will be key to any flood
threat. Fortunately, the speed of the system should preclude more
widespread hydro concerns, with the most likely solution being more
typical nuisance urban and poor drainage flooding. Isolated
instances of flash flooding can not be ruled out though, but
areal extent of this appears low at this time.
The front advances offshore into early Saturday and high pressure
builds in from the NW during the weekend with dry conditions and
more comfortable dewpoints. High temperatures will be pretty close
or just above normal on Saturday and Sunday. Ridging develops across
the East late this weekend and early next week, likely bringing the
most prolonged heat spell of the year thus far. Global ensemble
means peg H85 temperatures around 20C mid next week. Coupled with
dew points well into the 60s, heat indices could approach or exceed
100F at times mid next week, especially north and west of NYC. This
could eventually necessitate the first heat headlines of the season
and the threat will need to be monitored. Generally stayed close to
the national blend with only subtle adjustments for this update.
&&
.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
High pressure in control through Thursday with a weak surface trough
lingering this evening.
VFR.
Generally light flow which may be variable into the evening. Coastal
sea breeze is moving slowly inland through this evening. Winds will
become more SW/S with its passage. Light and variable to light SW
flow overnight once again strengthening out of the SW Thursday
morning 10-15kt. Some gusts Thursday afternoon may be 20-25 kt,
especially along the coast.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of sea breeze passage may vary by a couple of hours.
OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...
Thursday afternoon: VFR. SW gusts 20-25 kt.
Friday: Mainly VFR. MVFR or lower possible in TSRA in the afternoon
and evening.
Saturday-Monday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Conditions are expected to remain below SCA thresholds on the
forecast waters through Thursday night with a relatively weak
pressure gradient in place. Latest Wavewatch guidance appeared
to be running slightly higher compared to current ocean buoy obs
so wave forecast used a blend of latest Wavewatch and the
previous forecast.
Southerly winds may occasionally gust toward 25 kt on the ocean
Friday and seas could approach 5 ft. These conditions improve by
Saturday, and sub SCA conditions are then expected on all waters
thru early next week.
&&
.HYDROLOGY...
Showers and thunderstorms Friday afternoon and early evening could
produce heavy downpours that lead to brief minor flooding. A general
half inch of rainfall is expected across the region, but localized
amounts could exceed 1 to 2 inches in areas that see longer duration
thunderstorms. Impacts will most likely be limited to minor urban
and poor drainage flooding due to the quick movement of this
system, but isolated flash flood instances can not be ruled out.
&&
.TIDES/COASTAL FLOODING...
-- Changed Discussion --
There is a moderate risk of rip currents along ocean beaches
on Thursday, becoming high on Friday with increasing southerly
flow and surf heights.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JM/DR
NEAR TERM...JM/DR
SHORT TERM...JM
LONG TERM...DR
AVIATION...MW
MARINE...JM/DR
HYDROLOGY...JM/DR
TIDES/COASTAL FLOODING...DR