000
FXUS61 KOKX 131131
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
731 AM EDT Thu Jul 13 2023
.SYNOPSIS...
A warm front develops northwest of the region and moves farther
north today. An associated cold front approaches from the west as
well today and will start to enter the region tonight. Multiple
areas of low pressure develop and move along the front, slowing
it down and eventually stalling it through 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 --
Added in some patchy fog for eastern sections of the region and
made some slight adjustments with hourly temperatures.
Otherwise, no other changes made. Forecast mainly on track.
The area is in the warm sector today. A developing warm front moves
farther north of the region. An associated cold front will be well
west of the region but will make its way relatively closer to the
area this afternoon.
For the Lower Hudson Valley, where there will be more surface based
CAPE and less CIN, there will be highest chance of showers and
thunderstorms. Farther southeast, less CAPE and relatively more CIN,
lesser chances of showers and thunderstorms there.
CAMs show afternoon convection initiating and moving in across
locations mainly to the north and west of NYC. Model forecast of
bulk shear 0-6 km AGL indicates 25-30 kt so combined with the
instability, there could be some strong to severe thunderstorms
with potential for hail and strong wind gusts. The CAPE from
forecast soundings has substantial amount between -10 degree C
and -30 degree C.
The initiation of convection today will be focused along a pre-
frontal trough ahead of the advancing cold front.
A more southerly component to the wind as well as a greater wind
speed will make for relatively cooler high temperatures but
dewpoints will be a few degrees higher compared to the previous day.
The forecast highs range from the upper 80s to lower 90s with heat
indices in the lower 90s with some mid to upper 90s. Since yesterday
featured max heat indices were only in the lower 90s, there
will not be two consecutive days of 95 to 99 degree heat
indices. Forecast heat indices today are expected to remain
below 100. Thus, the forecast region is not meeting local heat
advisory criteria.-- End Changed Discussion --
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
-- Changed Discussion --
The cold front will begin to enter into the region tonight. Forecast
models indicate frontal entrance towards Lower Hudson Valley late in
the evening and then slowly moving southeast through overnight into
the more coastal sections of the region. There is a wave of low
pressure the models are also resolving to form and move along the
front. The low pressure wave will slow down the front and will help
enhance rainfall. More waves of low pressure develop along the
front move northeastward Friday into Friday night. Enhancing
lift will be a departing upper level jet streak early Friday
with its right rear quadrant near the region.
There are model differences with the timing of individual low
pressure waves, the cold front and therefore differences with the
timing of groups of showers and thunderstorms. The NAM Nest
convection depicts a line of showers and thunderstorms moving in
late evening to the north and then moving southward into the local
region for overnight whereas other CAMs keep the convective line
north of the forecast region.
With a majority of the CAMs indicating not much of any convection,
lowered the POPs for tonight with a south to north gradient to the
POPs. The northern half of the forecast region will have a higher
chance for showers and thunderstorms compared to the southern half.
Again, model bulk shear 0-6 km AGL indicates around 30 kt so
combined with the CAPE, again there could be some strong to severe
thunderstorms with potential for hail and strong wind gusts,
tonight into Friday night.
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 /11Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
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-- End Changed Discussion --
&&
.MARINE...
-- Changed Discussion --
Sub-SCA conditions in the marine forecast 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.-- End Changed Discussion --
&&
.HYDROLOGY...
-- Changed Discussion --
Multiple rounds of showers and thunderstorms are expected
through Friday night. Moderate to heavy rain will be possible
especially tonight through Friday. The Weather Prediction Center
has placed the forecast area in a marginal risk for flash
flooding today 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...
-- Changed Discussion --
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.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...BC/JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...BC
AVIATION...BC
MARINE...BC/JM
HYDROLOGY...BC/JM
TIDES/COASTAL FLOODING...