Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
1042 PM EDT Friday Mar 14 2014
a cold front approaches tonight and moves through the area
Saturday...followed by high pressure through Sunday. A complex
storm system developing over the Southern Plains this weekend
will track to the southeast coast Sunday night with secondary
development off the middle Atlantic coast. Both systems will move
east out to sea early next week as Canadian high pressure builds in
from the north. Another storm system affects the region during the
middle of next week.
Near term /until 6 am Saturday morning/...
forecast on track with just some minor adjustments to temperatures
and dew points to reflect latest observations.
Otherwise...clouds lower and thicken...and with a SW
flow...temperatures should be fairly steady through the night. An
approaching shortwave and cold front will provide lift for a
chance of precipitation after midnight. Temperatures aloft look to
be warm enough for precipitation type of rain. There is a chance
that it will be cool enough aloft over the far northwest zones for sleet
too...but will go with the probability that it will be rain.
Short term /6 am Saturday morning through Sunday/...
chance of showers ends during Saturday morning as the cold front and
shortwave pass through. A moderate west downslope flow will help
scour out clouds...so looking at a mostly sunny late morning and
afternoon for most spots. The exception would be over the northwest zones
where a cyclonic flow aloft and some moisture transport from the
lakes would lead to more cloud cover. Compressional heating from
this downslope flow will also help boost high temperatures to above
normals. Afternoon 850mb temperatures are forecast to be near -4c...so went
slightly above a NAM/mav MOS blend for highs.
Cold air advection becomes more noticeable Saturday night with high
pressure building in from the northwest. Winds will probably be strong
enough to prevent late night decoupling...resulting in lows near
With high pressure still nosing in from the northwest...Sunday starts out
as a mostly sunny day. Clouds will then increase as moisture in
association with a developing low pressure system in the lower
Mississippi/Tennessee Valley area streams in. Subsidence from high
pressure will help limit the mixing to around 900mb...where
afternoon temperatures are modeled to be near -10c. Went a couple of
degrees below mav/NAM MOS blend for highs...which will be below
Long term /Sunday night through Friday/...
focus is on the complex scenario leading to a potential snowstorm
Sun night/Monday that may impact the local area.
The 00z/14 deterministic runs continued to show a northern trend in
the track which continues to support the idea from suny sb
sensitivity analysis...however todays 12z model suite has
interestingly shifted south. This inconsistency stems from the
interaction between the shortwave trough that just moved onshore in
the Pacific northwest and the southern stream trough/cutoff low over the SW US.
Degree of phasing of these two features...and ejection of shortwave
energy from this trough and the eventual progression of the trough
itself...will determine eventual impacts to the area. Also need to
keep an eye on the strength of the Canadian high building in to the
north as it could become the main player and the March 3rd storm or
better the non-storm is still in recent memory. The high during that
event was about 10 mb stronger than it is currently forecast to be
for this one.
While the 00z/14 gefs..naefs and ec ens means are in good
agreement...the 00z/14 sensitivity analysis is still indicating a
large degree of spread in mslp to the north of each of the mean
tracks...implying that the track would be further north. The sensitivity
signal first appears on land at 00z/15 and appears to be associated
with the shortwave in the Pacific northwest. Will be able to gain some better
insight after tonight's 00z and even more after tomorrows 12z runs
now that this shortwave can be sampled much better by upper air
observations. A comparison of the amplitude of the 500 mb flow over the
eastern Pacific Ocean and Pacific northwest can be made as well and determination
if these northern track solutions are plausible or not. The cold Canadian
high pressure building in to the north will provide the cold air needed for
a snow event...but this too could become questionable across
portions of the area if the spread in the ens means comes to
Am not jumping on the suppressed solutions yet since there are still
many questions to be answered...so the potential for several inches
of snow remains possible. Not quite sure if we would be able to
reach warning criteria (6 inches) in a overrunning pattern...but the
higher quantitative precipitation forecast values are just south of the area and it is still cold
enough for snow.
High pressure ridge shifts to our east during Tuesday night.
Resulting onshore flow pushes some low level moisture our way. Too
difficult to tell this far out in time whether there will be
enough low level lift to squeeze out any light precipitation from
this...so will go with a dry forecast. Better chances of
precipitation begin on Wednesday as a low pressure system moves
through the Great Lakes region. Deeper moisture here and probably
some positive vorticity advection warrant slight chance/chance
probability of precipitation. Timing of best chances of precipitation in still question
with models in disagreement. They all seem to agree however that
the parent low passes to our north. Thinking is that the best
chances are during Wednesday and Wednesday night...but will continue
with a chance into Thursday due to this uncertainty. Looks like
mixed precipitation with anything that falls Wednesday
morning...then precipitation in the form of rain would be likely
Rest of the long term probably dry with high pressure influence.
High temperatures Wednesday through Friday fairly close to normal.
Aviation /03z Saturday through Wednesday/...
a cold front approaches from the northwest overnight...then crosses
the area Saturday.
Mainly VFR through the taf period. Possible exceptions are at
kgon and kswf which could experience MVFR conditions in -shra
Saturday morning ahead of front...otherwise expect ceilings around
5000 feet with -shra ahead of front.
S-south-southwest diminish to around 10kt or less late this evening...with low level wind shear
the main issue into the overnight hours...with winds at 2000 feet at
Winds veer to the west by middle morning and become gusty again...with
gusts 20-30kt - highest southern terminals. Winds become west-northwest by
late evening at 10-15kt and should cease to be gusty around the
Outlook for 00z Sunday through Wednesday...
Saturday night...VFR. Northwest wind g20-25kt possible.
Sunday...VFR. Northwest wind g15-20kt possible.
Sunday night-Monday evening...snow likely...especially New York metropolitan
and Long Island...IFR. NE wind g25+ knots possible Sunday night-
Late Monday night-Tuesday...VFR. NE wind g20-25kt possible.
Wednesday...MVFR or lower possible in -ra.
winds and seas on the non-ocean waters have struggled to gust to
25 knots this evening...so have cancelled the Small Craft Advisory
there. Have continued to keep the mention of occasional gusts to
25 knots possible. On the ocean...both winds and seas will be at
advisory levels through Saturday.
A cold front crosses the waters Saturday morning...and Small Craft Advisory
conditions continue through the day on the ocean waters.
Elsewhere...gusts will be at marginal levels...and another Small Craft Advisory
could be needed for a portion of the day.
Winds and seas subside Saturday night and Sunday...with sub-Small Craft Advisory
conditions on all water possible by late Saturday night.
High uncertainty with the potential storm slated to impact the
area Sun night/Monday which will ultimately affect the severity of
the marine forecast and associated headlines. Small Craft Advisory possibly
accompanies this system...developing Sun night with the potential
for gale force winds on the ocean waters Monday. Seas will likely
linger on the ocean waters after winds subside but timing of all
of this also needs to be worked out over the next few days.
Next chance of Small Craft Advisory conditions thereafter will be on the ocean
waters Wednesday night as an onshore brings in a building southeast
swell...pushing seas up to 5 feet.
scattered light precipitation of less than a tenth of an inch is
expected late tonight into Saturday morning.
Significant precipitation in the form of snow is possible from Sunday
night through Monday night...with the higher amounts expected across
NYC metropolitan and Long Island. It is still too early to specify exact
the National oceanic and atmospheric administration weather radio transmitter that serves the New York City
metropolitan area remains out of service due to radio frequency
interference with the U.S Coast Guard transmitter.
For more information see the following public information
statement (all lower case):
Marine...Small Craft Advisory until 6 PM EDT Saturday for anz350-353-