Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
1250 am EST Wednesday Dec 11 2013
low pressure passes well southeast of Nova Scotia tonight as
strong high pressure builds in from the south and west. The high
moves offshore Wednesday with a weak cold front moving across
Wednesday night. High pressure returns Thursday...passing south
Friday. A coastal storm will likely impact the region this
weekend...with high pressure returning early next week.
Near term /until 6 am this morning/...
winds not quite gusting over land areas as much as offshore where
there is better mixing due to the warmer water temperatures. The highest
gusts may be right along the coast overnight with gusts up to 30
miles per hour...with gusts of 20 miles per hour or less elsewhere. Otherwise...a few
minor adjustments were made to account for initial conditions.
Strong subsidence was noted on latest water vapor imagery across
the region with clear skies. A tight pressure gradient between low
pressure east of the Canadian Maritimes and high pressure building
east across the Ohio Valley will allow for gusty west winds as
previously mentioned. This will help advect in colder air along with
wind chill values dropping off into the single digits well inland
and the teens elsewhere by morning.
Lows still on track for 15 to 25 degrees degrees f.
Short term /6 am this morning through 6 PM Thursday/...
high pressure continues to build in early...then gradient relaxes
later in the day as high pressure moves off the Carolina coast.
Another longwave trough sinks south into the Ohio Valley Wednesday
afternoon and Wednesday night. A cold front from the north and
west approaches late in the day and moves across at night. This
will be scarce in moisture but will deliver a very cold airmass
behind it. There will be a slight chance of snow showers across
portions of the region...mainly lower Hudson Valley and southeast
Long Island. Highs Wednesday were a mav/met blend. They were in
good agreement. Highs will range mainly in the lower 30s. Lows
Wednesday night will range from middle teens to middle 20s once again.
Winds stay up near the coast...mitigating radiational cooling but
will be less magnitude compared to the previous night.
Long term /Thursday night through Tuesday/...
upper trough extending across eastern Canada and the northeast
United States departs late this week as another shortwave dives out
of central Canada...passes across the Great Lakes region late this
weekend...then tracks across the northeast early next week.
Meanwhile...southern stream trough departs the SW United
States...moving across the middle section of the country...passing just
to our south Sunday. This may outrun northern stream trough...with
split flow dominating.
At the surface...cold air remains entrenched across the northeast
behind departing trough early this time frame. High pressure builds
to the west Thursday...passing to the south off the middle Atlantic
coast late Friday. Meanwhile...another cold front crosses the area
Friday night as high pressure builds well to the north early
Then attention turns toward the Gulf states as low pressure
associated with southern stream trough moves northeast. Parent low
remains well to the west Saturday and Saturday night as coastal low
develops near the Carolinas and moves off the middle Atlantic
coast...likely passing just inside of the 40/70 benchmark early
This coastal low deepens late this weekend and early next week as it
tracks across the Canadian Maritimes. High pressure builds Tuesday.
As for sensible weather...dry conditions expected Thursday through
Friday. A few flurries are possible as the atmosphere moistens
Friday night...with the passage of the front.
As for Saturday/Saturday night...models have trended colder this run.
With very cold air is in place...snow will begin sometime Saturday
morning all locations. Warm air advection will be underway...and a
gradual warmup is expected to occur. Exact details/timing still in
question...but at this time would expect snow Saturday gradually
changing to rain near the immediate coast...with predominately snow
Snow accumulations are likely...with time to fine tune details as we
get closer to the event.
Any precipitation ends Sunday...with dry conditions expected
thereafter...early next week.
As for temperatures...well below normal per NAM/GFS MOS Thursday. Will lean
toward colder wpc numbers Friday...several degrees colder than
latest mex numbers as cold air looks to remain in place.
Cold temperatures Saturday...with a late day warmup expected...mainly near
the coast. Then well below normal once again Monday and Tuesday per
Aviation /06z Wednesday through Sunday/...
high pressure will build in through Wednesday...with high confidence VFR
conditions. Forecast gusts in westerly flow could abate or become
infrequent for a time from about 09z-13z...then should be more
frequent from about 13z-19z.
Outlook for 06z Thursday through sun...
Thursday...VFR. West-northwest flow with gusts up to 20 knots.
Sat-sun...IFR in mixed wintry precipitation. Chance east-northeast gusts 30-35 knots Sat
have downgraded the gales on the ocean waters to Small Craft Advisory as gusts
aren't frequently reaching 35 knots. They come close at times...but
do not feel a gale is warranted with winds expected to slowly
decrease through the overnight. Will mention occasional gusts up
to 35 knots early in the coastal waters forecast however. Small craft wind gusts for all
other waters remains.
Boundary layer winds decrease Wednesday with the lower pressure
gradient. Gales lower to small craft conditions on ocean. Small
craft conditions will also be present on all other waters. This
become more marginal in the afternoon with gusts only reaching
around 20 knots before picking up again Wednesday night.
Ocean seas generally 4 to 7 feet through Wednesday night.
A tight pressure gradient remains across the waters Thursday into
Friday as high pressure builds to the west Thursday...and passes to
the south Friday. Gusty conditions are expected Thursday as northwest winds
eventually back to the west Thursday night and Friday. Winds are
forecast to diminish ahead of a weak cold front late Friday and
Then expect winds to increase ahead of low pressure and associated
frontal boundary Saturday. Easterly winds Saturday shift Saturday
night as the center of the low moves across the waters. Then gusty
northwest flow is expected late this weekend behind the storm.
Seas remain rough through much of the period due to the strong
winds. Followed wave watch iii output closely...but bumped up seas
slightly at the start based on expected winds.
there is the potential for significant precipitation this weekend
in association with a coastal low pressure system.
due to interference issues with the U.S. Coast Guard
emergency broadcast channel...the New York City National oceanic and atmospheric administration all hazards
weather radio station kwo35 remains out of service. The National
Weather Service is working with several U.S. Government agencies
to isolate and resolve this technical problem.
During this time...the transmitter may be returned to service
intermittently for use of the National oceanic and atmospheric administration all hazards weather radio
during potentially dangerous weather situations...for routine
weekly tests of the warning system...and to determine if the
interference issue has been resolved.
Marine...Small Craft Advisory until noon EST today for anz330-335-338-
Small Craft Advisory until 6 PM EST this evening for anz350-