456
FXUS61 KOKX 052059
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
359 PM EST Sun Jan 5 2025
.SYNOPSIS...
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A quick moving low will pass through the Mid Atlantic region on
Monday and offshore Monday night. High pressure then slowly
builds in from the west through Friday. An area of low pressure
may pass nearby next weekend.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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The pressure gradient over the area weakens tonight, while heights
rise slightly aloft. Surface winds gradually lower through tonight,
becoming light (5 kt or less) for a period. Stratocu should slowly
decrease through the evening for much of the area as model
soundings show the lower levels drying out.
Given the loss of cloud cover and light winds, there could be a
brief period where temps drop quick this evening. However, mid
to high level cloud cover moves in the second half of the night,
so radiational cooling conditions are not ideal for the entire
night. Forecast lows are in the low to mid 20s for most. Given
the aforementioned brief period of efficient cooling, the usual
cold spots could potentially see lows in the mid to upper teens.-- End Changed Discussion --
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
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A surface low currently centered over Arkansas, and the associated
upper level low, will lift towards the Mid Atlantic tonight and move
offshore sometime late Monday morning into Monday afternoon. The low
is still progged to pass well south of the area, about 300 miles
offshore. As it passes to the south, it will deepen as the
upper level low opens up and become negatively tilted.
There were no major trends/changes with the 12z guidance. QPF
overall did come down a hair compared to the 00z guidance for
most locations, however, forecast SLRs were increased a bit from
the previous forecast, so snow amounts have generally stayed
the same or increased by a tenth of an inch.
The story remains the same. As the low passes to the south we look
to get scraped by the far northern edge of the precip shield. With
plenty of cold air in place, this will result in an all light snow
event. In fact, most places likely do not get above freezing on
Monday. All guidance is in agreement with strong 850 frontogenesis
staying well offshore and in turn any snow banding will stay well
south of the area. Light snow likely enters northeast NJ and
NYC around 10am and will be done by 3 to 4pm. There could be a
period between noon and 2pm where snow rates reach 0.2 to 0.4
inch/per for one hour based on model consensus timing of
strongest lift and hourly QPF fields.
As mentioned, totals have largely stayed the same as the previous
forecast. Extreme southwestern portions of the area (Union, Staten
Island, Brooklyn and southern Queens) look to have the best chance
at seeing an inch. On the other hand, much of the Lower Hudson
Valley and southern CT likely do not see more than a trace. Not
expecting a significant shift as we are within 18-24 hours, but
if the system does end up tracking a bit farther north than
forecast then reasonable worst case amounts for the southwestern
portion of the area are around 1.5 to 2 inches.-- End Changed Discussion --
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
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Key Points:
* Cold, windy, and predominantly dry conditions expected through the
upcoming week. Daytime wind chills generally in the teens and as
low as the single digits overnight.
* Next chance for widespread precipitation could arrive next weekend.
Globals models are in good overall agreement this period with the
mean upper trough across eastern Canada extending into the NE
quarter of the CONUS. This will keep the area dry and unseasonably
cold through much of the week. A pattern change toward the end may
end with potential impacts from a storm system tracking across the
southern states.
Blocking over Greenland with positive height anomalies will allow a
polar vortex over the Canadian Maritimes to only slowly lift out to
the NE through the week. At the same time, ridging remains in place
across the E PAC into western Canada. This will allow for a steady
stream of polar air reinforcements through Thursday. During this
time, expect temperatures about 10 degrees below normal.
Temperatures likely don`t get above freezing until Friday. NBM box
and whisker plots continue to show the deterministic highs at or
above the 75th percentile through the period, but closer to the
median (50th) for lows. Stayed with a blend of the NBM with its
median for highs to air slightly on the colder side. At the same
time, polar high pressure over the Plains and Midwest bleeds south
and east, weakening as it does so through the week. This will
maintain a tight pressure gradient into Friday, with a strong W/NW
flow. Expect gusts of 30 to 40 mph each afternoon, possibly near
advisory levels for Tuesday. This will generate wind chills
generally in the teens each day and as low as the single digits at
night.
The upper air pattern briefly looks to get interrupted as a piece of
Pac energy breaks through the ridge over western Canada. It is the
interaction of this piece of energy along with a cutoff low over the
desert SW that brings a storm system across the southern tier of
states. The 12Z globals have reverted to a more progressive, weaker
system with low pressure passing off the Carolina coast next
Saturday. This is quite different from some of the previous runs the
last 24h, which rapped up an intense coastal low just south and east
of the area. This system will bring the next chance for
precipitation to the area. It is much too early though to rely on
any one solution and it will need to be watched the next few days.-- End Changed Discussion --
&&
.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
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Weak low pres passes S of the region on Mon.
VFR thru tngt, then clouds lower Mon mrng. MVFR expected aft 12Z,
with pockets of IFR possible in steadier snow roughly 14-19Z.
Improvement to VFR by 20-22Z Mon.
Runway accums less than an inch expected.
Flow generally 280-300 true thru tngt. Decreasing winds aft 22Z,
with speeds blw 10kt all arpts by 6Z. Lgt flow blw 10kt on Mon with
winds veering slightly to 340-360 true.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments possible for timing and intensity of -SN on Mon.
OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY...
Rest of Monday: VFR by 20-22Z. Winds increase again aft 00Z Tue with
NW gusts up to 30kt.
Tuesday through Thursday: VFR and windy. Gusts aoa 35kt at times.
Friday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
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A Small Craft Advisory remains in effect on all waters until this
evening for 20 to 30 knot gusts and 5 to 7 ft seas across the ocean
zones. As winds lower, the SCA expires gradually from west to east.
Quiet conditions are then expected on Monday before winds ramp back
up again Monday night to SCA level. Given 15-25 kt winds and cold
air and water temps Monday night, there is also a chance of some
light freezing spray. This is mainly for the LI Sound and close to
the shore on the ocean waters where water temps will be coldest. If
water temps trend colder than forecast, light freezing spray could
be more widespread.
A Gale Watch has been issued for all Tuesday into Wednesday due a
strong pressure gradient and several shots of cold air moving across
the relatively warmer waters. Strong low pressure will reside across
the Canadian Maritimes during this period with high pressure
building in from the west. Gales could linger into Thursday,
especially for the ocean waters.-- End Changed Discussion --
&&
.HYDROLOGY...
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No significant hydrologic issues anticipated through next weekend.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 10 PM EST this evening for ANZ331-
332-335-338-340-345-355.
Gale Watch from Tuesday morning through Wednesday afternoon
for ANZ331-332-335-338-340-345-350-353-355.
Small Craft Advisory until 4 AM EST Monday for ANZ350.
Small Craft Advisory until 1 AM EST Monday for ANZ353.-- End Changed Discussion --
&&
$$
SYNOPSIS...JT/DW
NEAR TERM...JT
SHORT TERM...JT
LONG TERM...DW
AVIATION...JMC
MARINE...JT/DW
HYDROLOGY...JT/DW