000
FXUS61 KOKX 131650
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1250 PM EDT Thu Jul 13 2023
.SYNOPSIS...
A cold front and associated pre-frontal trough approach from the
north and west through this evening. The front then settles over
the area tonight and remains nearby into Friday night.
Unsettled weather is expected much of the time from Saturday
through Thursday as a series of frontal boundaries move across
the area.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
The forecast is generally on track through this evening.
Main concern continues to be with potential of convection late
this afternoon/early this evening for the interior. Starting to
convection forming ahead of the pre-frontal trough/cold front
across western Upstate NY early this afternoon. This activity is
handled well by the CAMs and is expected to approach late in the
day and this evening. Trends have indicated that this may occur
a bit later than previously thought. However, the HRRR has
hinted at some isolated convection developing this afternoon,
possibly from sea breeze convergence. Large scale support is
limited however and the main trigger is the surface front and
pre-frontal trough.
The atmosphere is unstable, but there is also a good amount of
middle level dry air to overcome. There is about 25-30 kt of
shear, so if the line does make it into the area this evening, a
strong to severe storm is possible across the Lower Hudson
Valley. If a pulse storm can initiate a bit further east this
afternoon, there could be a strong gust as well. There is a
substantial amount of CAPE between -10C and -30C, so hail cannot
be ruled out. Locally heavy rainfall is possible in any
shower/storm. The threat is limited around the Hudson River
corridor on east this afternoon due to a bit more CIN and the
aforementioned dry air aloft. Based on latest trends and
collaboration with neighboring offices, no flood watch was
issued across the interior or southern CT. The flow is strong
enough that if the line does make it into our area, it will move
through quickly enough to prevent any significant
rainfall/flooding.
Highs today range from the upper 80s to lower 90s with heat
indices in the lower 90s with some mid-upper 90s in the usual
warmer spots. Yesterday`s heat indices peaked in the low 90s, so
the two consecutive days of 95 to 99 degree heat indices will
not be met for an advisory.-- End Changed Discussion --
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
-- Changed Discussion --
The cold front will begin to enter into the region tonight. The
latest 12z guidance indicates the boundary may stall across the
interior overnight with the line of convection weakening. The
12z NAMNest does have the line making through the entire region,
but this is an outlier at this time based on the general
consensus. Earlier guidance that indicated a wave developing on
the front has backed off with just a low chance for some
isolated-scattered convection overnight into early Friday
morning.
Layer precipitable water increases to near 2 inches late tonight
through Friday night. This will be an indication of the airmass
becoming very humid to allow for any thunderstorm to produce
torrential downpours.
The showers and thunderstorms continue at times Friday through
Saturday. There will likely be lulls in the activity so it will
not rain the entire time. Heavy rain will become primary threat
without too much change in CAPE. With nearly parallel flow from
lower to upper levels, there will be training of showers and
thunderstorms where showers and thunderstorms develop and move
across the same area. This will increase the flood threat. Still
not nearly high enough confidence to go with any flood watch
however.
The CAMs have much variety in their reflectivity forecasts so
the forecast confidence on the timing of showers and
thunderstorms and where the heavy rain will occur is low.-- End Changed Discussion --
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Stuck fairly close to the NBM through the long term period
overnight, with unsettled conditions continuing through much of the
time frame.
Saturday night and Sunday, yet another upper level shortwave and
surface trough/low pressure approach the region and move across the
area. Once again, with a rather humid airmass in place, PWATS values
over 2.25 inches, heavy rainfall will be possible. WPC continues to
keep a large portion of the CWA in the day 4 ERO outlook (Slight
Risk).
Additional rounds of rainfall continue into the middle of next week,
and with antecedent moisture at least a nuisance flood risk will
remain.
Conditions remain warm and humid through much of next week, with
highs in the 80s and lower 90s.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
A weak frontal boundary will remain north of the terminals
today. A cold front then approaches tonight into Friday.
Generally VFR and dry for most terminals through 00z. Forecast
becomes a bit tricky with placement of any showers and
thunderstorms. Latest CAMS keep most of the shower and
thunderstorm activity north of the NYC terminals, however there
are still a few models showing some thunder at the NYC terminals
after 00z. With so much uncertainty will only carry a PROB30 at
KSWF where the highest confidence of thunder occurring is
expected. The timing of the PROB30 may have to be adjusted by an
hour or two. Otherwise, will leave the NYC terminals dry for
now, based on low confidence on timing and placement for any
storms.
Light and variable winds this morning become SW-S 12-16 kt, on
average, with gusts 18-25kt by midday with additional sea
breeze enhancements developing by afternoon. Winds become light
once again tonight.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
AMD possible for start time of gusts this afternoon.
Low confidence of any shower activity in and around the NYC
metro terminals tonight into Friday morning.
OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
Friday: Showers/thunderstorms likely with MVFR, IFR possible at
times in the afternoon.
Friday night: Chance of evening showers/thunderstorms, then MVFR or
lower conditions possible.
Saturday: MVFR or lower possible in the morning, otherwise VFR with
a chance of showers/thunderstorms in the afternoon and evening.
Sunday and Monday: Chance of showers/thunderstorms with MVFR or
lower.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Sub-SCA conditions expected through Saturday night. Brief 25 kt
gusts on ocean western Long Island late this afternoon are
forecast, but only occasional.
Sunday into the first part of next week, conditions are expected to
remain below SCA levels.
&&
.HYDROLOGY...
-- Changed Discussion --
Locally heavy rain is possible from any shower or thunderstorm
through Friday night. The Weather Prediction Center has placed
the forecast area in a marginal risk for flash flooding into
tonight and a slight risk for flash flooding Friday into Friday
night. Smaller streams and fast responding rivers may flood,
along with urban and poor drainage areas.
Additional rounds of moderate to heavy rain will be possible
Saturday and Sunday, and the threat of flash flooding and
nuisance and minor flooding of poor drainage areas remains.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
There is a moderate risk of rip current development at all the
ocean beaches today through Friday.
Southerly winds with southerly swells of 2-3 ft will be in place
across the ocean beaches during this time period.
If winds trend higher than forecast however, a high risk of rip
current development would occur at the ocean beaches.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...BC/JM
NEAR TERM...DS
SHORT TERM...JM/DS
LONG TERM...BC
AVIATION...BC/DW
MARINE...BC/JM
HYDROLOGY...BC/JM
TIDES/COASTAL FLOODING...