Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service New York New York
639 PM EST Thursday Feb 11 2016

Synopsis...
low pressure over the Canadian Maritimes continues to lift to the
northeast...while high pressure to the west builds across the Middle
Atlantic States by morning. An Arctic cold front will approach
Friday night...and pass through toward daybreak Saturday. Arctic
high pressure then builds in from the west...settling right across
the region Sunday night. The high pressure area shifts east of the
region Monday...with a developing low well west of the region that
will be approaching. The low moves across Tuesday through Tuesday
night. Another cold front moves across Wednesday with high
pressure starting to build thereafter.

&&

Near term /until 6 am Friday morning/...
the snow showers along with most of the clouds have dissipated
early this evening...with cloudiness confined to along the
coast...which will dissipate as high pressure and drier air moves
in this evening. High pressure over the Midwest builds east and
into the area by daybreak.

Very cold temperatures tonight combined with the gusty winds will
produce wind chill values in the single digits. Some readings may
even be near or below zero. Used a met/mav MOS blend for overnight
lows...ranging from single digits inland...to the lower and middle
teens at the coast. This is below normal by 10 to 15 degrees.

&&

Short term /6 am Friday morning through Friday night/...
another cold day is on tap for Friday with highs in the lower to middle
20s. Winds will be substantially lighter as high pressure passes
south of the area in the morning. An amplified upper flow with
ridging across western North America then allows the polar vortex to
drop south across Hudson Bay and into southeast Canada Friday into Friday night.
This will send an Arctic cold front over the upper Great Lakes Friday
morning into the lower lakes by Friday evening...with the cold frontal
passage toward daybreak Sat.

Middle and high level clouds will move into the area Friday after and
then lower as large scale height falls move into the area in the
evening. There looks to be enough moisture and lift for scattered snow
showers. Models also have been showing a higher probability across
eastern Li/southeast CT after midnight as a weak inverted trough sets up to
the northwest of a coastal low passing well south and east of the area. At
this time...not expecting much more than a dusting...but perhaps a
light accumulation across eastern areas is not out of the question.
Confidence is low for measurable snow at this time.

Temperatures Friday night will actually be nearly steady in the upper teens to
the lower 20s...before dropping off sharply behind the Arctic cold
front Sat morning. Readings will be in the lower teens by morning
across the interior...to the middle and upper teens at the coast.

&&

Long term /Saturday through Thursday/...
looking at the large scale with the upper level jet stream...this is
well south of the region for this weekend into Monday. The jet
splits for Monday night through Tuesday. A jet streak maximizes in
speed west of the region Tuesday...associated with a negative
tilting sharpening trough. The jet again pushes south of the region
for the middle of next week with a ridge to the west approaching for
next Thursday.

A deep middle level low at 500mb pushes south into New England Saturday
and moves east towards Nova Scotia Saturday night into Sunday. More
of a split flow at 500mb after that with weak shortwave approaching
from the west for early next week. The trend for geopotential
tendency at this level will be positive Sunday night through Monday.
A sharpening trough approaches Monday night and moves across Tuesday
into Tuesday night. A general negative trend resumes thereafter in
the height tendency with another large shortwave trough moving in
for Wednesday and Wednesday night timeframe.

Extremely cold weekend with highs staying below 20 degrees or below.
Wind chills range -15 to -30 Saturday night into early
Sunday...coldest across the interior where wind chill watch has been
issued. Overall...wind chills stay in the single digits to
below zero for much of the weekend. Some rebound in temperatures
early next week especially Tuesday with warm air advection
allowing for temperatures in the upper 40s to near 50.

Precipitation...snow showers Saturday mainly south of Long Island in
response to inverted trough. The high pressure area still well west
of the region. The high moves closer Saturday night into Sunday.
Gusty winds Saturday and Saturday night with a decrease in winds
Sunday as high center approaches. The high center moves overhead
Sunday night and offshore Monday. Another low approaches from the
west Monday night and moves across Tuesday into Tuesday night.
Initially winter precipitation will transition to all rain Tuesday which
could be potentially heavy at times.

After the low...cold air advection resumes but no extreme cold is
expected. The temperatures will trend to close to normal. There will
be another chance for snow showers Wednesday into Wednesday evening
as another cold front moves across. Drier trend to weather late
Wednesday night into next Thursday with high pressure returning from
the west.

&&

Aviation /00z Friday through Tuesday/...
weak high pressure remains over the region into tonight.

VFR. Moderate to high confidence westerly winds diminish
tonight...and become SW on Friday.

New York metropolitan enhanced aviation weather support...

Detailed information...including hourly taf wind component forecasts can
be found at: http:/www.Erh.NOAA.Gov/zny/n90 (lower case)

Kjfk fcster comments: 30kt gusts possible through 02z or so.
Directions primarily left of 310 magnetic this evening.

Klga fcster comments: 30kt gusts possible through 02z or so.
Directions primarily left of 310 magnetic this evening.

Kewr fcster comments: 30kt gusts possible through 02z or so.
Directions primarily left of 310 magnetic this evening. Occasional gusts up
to 20 knots possible Friday afternoon.

Kteb fcster comments: gusts may diminish 1-2 hours earlier than
forecast.

Khpn fcster comments: gusts may diminish 1-2 hours earlier than
forecast.

Kisp fcster comments: gusts may diminish 1-2 hours earlier than
forecast.

Outlook for 00z Friday through Tuesday...
Friday...VFR.
Saturday...mostly VFR. Chance sub-VFR possible in brief -shsn. Northwest
gusts around 35kt.
Sunday...VFR.
Monday...VFR daytime...chance sub-VFR with snow and rain/snow mix at
night.
Tuesday...sub-VFR and rain. Chance mixed precipitation early. Southeast-S gusts to
30kt possible. Chance low level wind shear.

&&

Marine...
just some minor tweaks to increase gusts on the ocean a couple of
knots and seas on the ocean a half to one foot. Otherwise the
forecast is on track.

Gales continue through the night on all waters but may need to be
dropped during the early morning hours Friday as high pressure
approaches from the west. Sub-Small Craft Advisory conditions are forecast Friday into
Friday night as SW winds develop ahead of an approaching Arctic cold
front. Frontal passage is forecast around daybreak Sat with northwest
gales developing soon thereafter.

Rough conditions for all waters this weekend. Gales likely
Saturday and Saturday night. Gales prevail into early Sunday before
decreasing to 20-30 knots during the day. Freezing spray expected as
well this weekend for most of the waters. Weak pressure gradient
Sunday night through Monday night will lead to below Small Craft Advisory conditions.
Conditions trend back up though ahead of low pressure next Tuesday
with Small Craft Advisory becoming probable once again.

&&

Hydrology...
liquid equivalent of less than a tenth of an inch is forecast Friday
night in the form of snow showers.

Low pressure moving up the coast has potential to produce liquid
equivalent quantitative precipitation forecast at least 1 to 2 inches. Part of this will fall as
snow initially...but then runoff via melting snow and heavy rain
Tuesday into Tuesday night could cause at least Urban and Small Stream
flooding problems. It is too early to say if main Stem rivers
would be affected.

&&

Climate...
with the extremely cold air mass forecast Saturday into
Sunday...record minimums and record low maximums may be reached.
Here are the records and forecasts...

Station......record/fcst minimum...record low maximum/forecast high
for 2/14 for 2/14

NYC...........2 (1916) / 3.............17 (1979) / 16
LGA...........1 (1979) / 5.............15 (1979) / 16
JFK...........4 (1979) / 4.............17 (1979) / 17
isp...........7 (2015) / 0.............26 (1987) / 14
ewr...........0 (1979) / 2.............15 (1979) / 16
bdr...........3 (2015*) / 0.............18 (1979) / 15

*in 1979 as well

&&

Okx watches/warnings/advisories...
CT...wind chill watch from Saturday evening through Sunday morning
for ctz005>012.
New York...wind chill watch from Saturday evening through Sunday morning
for nyz067>070.
New Jersey...wind chill watch from Saturday evening through Sunday morning
for njz002-103.
Marine...Gale Warning until 6 am EST Friday for anz330-335-338-340-345-
350-353-355.

&&

$$

National Weather Service Glossary of Abbreviations