270
FXUS61 KOKX 302250
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
550 PM EST Sat Nov 30 2024
.SYNOPSIS...
The region will remain between broad low pressure over southeast
Canada and high pressure building into the Mississippi and
Tennessee Valleys into early next week. High pressure weakens
Wednesday as a clipper low passes to the north through Thursday
night, bringing a cold front across the region Thursday. High
pressure builds in thereafter.
&&
.NEAR TERM /THROUGH SUNDAY/...
-- Changed Discussion --
KOKX 88D showing a few weak bands of flurries/sprinkles working
through central and eastern LI and southeast CT this evening.
Several MPING reports have noted flurries, including in
Riverhead and SE of Stony Brook, NY, as well. Have updated PoPs
and WX to account for these bands as they move southeast. With
dewpoint depressions of 10-15 degrees, not expecting much more
than an isolated flurry or perhaps brief light snow shower
across the twin forks of LI over the next couple of hours.
A sheared out 500 mb vortmax will pivot across the area this
evening. CAMs have continued to signal some very light
convective precipitation near the Forks of Long Island this
evening. Stratocu is beginning to develop with the vortmax
approaching and steepening lapse rates and anticipate a few of
these will organize just enough for some flurries across the
Forks. The subcloud layer is dry and dew points in the teens
will limit intensity if any flurries reach the ground. This
activity will push offshore 6-8pm.
Skies should become mostly clear tonight behind the passage of
the vort max. The broad upper trough will remain over the
eastern CONUS and is likely to amplify a bit tonight. Another
area of energy begins to rotate around the base of the trough
late tonight into Sunday morning. Model time heights are not as
saturated as they were in the guidance 24 hours ago. However,
there is enough moisture to increase mid and high level clouds
especially across the southern half of the area Sunday morning.
The shortwave energy passes east in the afternoon allowing skies
to become mostly sunny in the afternoon.
Lows tonight will range from the upper teens inland to the lower
and middle 20s elsewhere. Highs will likely end up a few
degrees cooler on Sunday with readings reaching the middle and
upper 30s for most spots except the coast should be able to
reach 40 degrees.-- End Changed Discussion --
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
Little change to the pattern is expected Sunday night through
Monday night. Low pressure will still be located over
southeastern Canada and high pressure will remain centered to
our southwest. The broad upper trough also will remain over the
eastern US. The pressure gradient should be weaker, especially
on Monday. Otherwise, it will remain mostly clear with just a
few to scattered stratocu at times, especially Monday afternoon.
Temperatures will continue several degrees below normal. Highs on
Monday will be in the upper 30s to low 40s. Lows both Sunday and
Monday night will fall into the upper teens and low 20s inland and
middle to upper 20s elsewhere.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Key Points
*Temperatures will run below normal through the long term period,
with highs likely not making it out of the mid 30s on Friday and
Saturday.
*A clipper low will bring light rain and snow and gusty winds to the
area Thursday through Friday.
The upper level trough over the area Tuesday morning will start to
flatten and a more zonal flow is expected by the afternoon. High
pressure over the Mississippi and Tennessee Valleys will continue to
be in control through early Wednesday.
Potent shortwave energy diving down from far northern Canada will
aid in deepening a clipper low as it passes over the Great Lakes and
to our north. This low will drag a cold front through the area
sometime on Thursday. The system is lacking any significant moisture
and only light QPF is seen across the guidance. This would likely
fall as snow across the interior and rain or a rain/snow mix along
the coast. The more impactful weather with this system will likely
be the cold air filtering in behind it and the gusty winds. By
Thursday night the low will likely be near Nova Scotia at around 980-
990mb. At the same time, high pressure starts to build into the Ohio
Valley strengthening to about 1030-1035mb. This will place the area
in a strong pressure gradient and lead to sustained winds around 20
to 25mph. Model soundings also show deep mixing in strong cold
advection which could lead to at least 30 to 35mp gusts. For now
blended in some NBM 90th and raw model data for winds and wind
gusts. Unless there are major shifts in guidance, would expect the
wind forecast to trend upward as we head into next week. The cold
front moves through sometime Thursday, but there looks to be a
secondary push of cold air Thursday night into Friday morning as the
upper level trough axis pushes through. This secondary push is
characterized by 850 temps between -12 and -15C Thursday night
through Saturday. The NBM deterministic max temps for Friday and
Saturday were closer to the 90th percentile values and was warmer
than raw model temps. Given the anomalous cold airmass, went
closer to NBM 50th, NBM75th and raw model temps for highs. There
is relatively high confidence that max temps don`t make it out
of the mid 30s on Friday. Spread between the NBM 25th and 75th
percentiles on Friday is only 3 to 4 degrees. Combine these cold
temperatures with the winds and wind chill values on Friday
will be down in the teens and 20s on Friday. Wind chill values
Friday night will be down in the single digits to low teens.
Current forecast has cold temps again Saturday, but model spread
increases a bit in placement of surface features. The latest
GFS has another low approaching from the northwest. This would
turn our winds southerly in the morning and lead to warmer
conditions. High pressure dominates on Saturday in the latest
Canadian and ECMWF. The GEFS also aligns more with the ECMWF and
Canadian deterministic.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
VFR. Mid and high level ceilings are possible late tonight into
the first half of Sunday.
Winds will be WSW at 10-15kt with occasional G20-25kt through
this evening. Any remaining gusts should start to taper off by
00Z. Winds remain westerly tonight around 10kt along the coast
with occasional gusts 15-20kt, slightly lower winds elsewhere.
Gusts are likely to redevelop on Sunday, especially at the NYC
and LI terminals before diminishing near 00Z.
...NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty...
Gusts may be more occasional than frequent into early this
evening.
End time of gusts this evening may vary +/- 1 or 2 hours.
However, occasional gusts up to 20kt are possible overnight.
OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY...
Sunday Afternoon: VFR. W winds G20KT.
Monday and Tuesday: VFR. NW winds G15-20kt Tuesday afternoon.
Wednesday: VFR during the day. Chance of sub-VFR in snow and/or
rain showers at night. SW winds G15-20kt.
Thursday: Mainly VFR. Slight chance of a rain and/or snow
shower. W winds G25-30kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
No changes were made to the SCA on the ocean through Sunday.
Winds will remain around 25 kt and seas near 5 ft tonight into
Sunday. Winds should begin to weaken Sunday afternoon with seas
subsiding below 5 ft. Conditions should then remain below SCA
levels Sunday night through Monday night.
Sub-SCA conditions expected Tuesday through much of Wednesday. Winds
and waves pick up Wednesday night ahead of a cold frontal passage
and potentially reach gale force by Thursday morning. The cold front
likely passes through Thursday afternoon and gale force winds could
continue through much of Friday out of the northwest. Ocean seas
during this time could peak around 10 feet. Conditions fall to SCA
level Friday night and then below SCA by Saturday.
&&
.HYDROLOGY...
There are no hydrologic concerns through the first half of next
weekend.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EST Sunday for ANZ350-353-355.
&&
$$
SYNOPSIS...DS/JT
NEAR TERM...DBR/DS
SHORT TERM...DS
LONG TERM...JT
AVIATION...DBR/DW
MARINE...DS/JT
HYDROLOGY...DS/JT