Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
1003 am EST Sat Feb 6 2016
a ridge of high pressure will build to our south today. Low
pressure tracking across Quebec will spread a few clouds into
northern and mountain sections later today along with scattered
snow showers. A trailing cold front will drop gradually south
across the region tonight and Sunday accompanied by a few snow
showers and mountain snow squalls. Low pressure in the Atlantic
will track to the northeast well to the east of Cape Cod on
Monday. Another low will take a similar track on Tuesday and
linger over the area through Thursday.
Near term /today/...
made a few adjustments to precipitation chances today as regional
radar shows some light snow moving through upstate New York
tracking along the Canadian border. Could see a few light snow
showers make it over to northern New Hampshire or northwest Maine.
Otherwise no significant changes needed.
minor estf update to ingest 11z mesonet and to reflect satellite
and radar trends in near term grids.
at 07z...a 1031 millibar high was centered over Virginia. A 1015
millibar low was centered over the upper Great Lakes. GOES
infrared imagery showed clear skies across the forecast area at
moment. However...there was a band of middle clouds upstream across
the eastern Great Lakes in advance of the Great Lakes disturbance.
They'll slide east into the forecast area with the most widespread
cloud cover...and any snow shower activity...confined to northern
and mountain sections. The circulation between the Great Lakes
disturbance and the building high to our south will allow
temperatures to climb into the 30s.
Short term /tonight and Sunday/...
the northern stream impulse and associated surface low track to
our north tonight and early Sunday. This will help drive a
trailing cold front southward across the forecast area. Across
northern and mountain sections we'll see the most widespread
clouds and snow shower activity with the front. There may even be
a few squalls across the mountains with its passage as well as
upslope clouds and snow showers behind it. On Sunday...we struggle
to get above 30f in the mountains behind the cold front...while
we'll warm into the 40s elsewhere as we await the colder airs
arrival following the cold frontal passage.
Long term /Sunday night through Friday/...
quite a bit of uncertainty remains in the evolution and tracks of
low pressure systems early next week. The main forecast challenges
remains the eventual sensible weather Monday through Wednesday.
The main players on The Table remain a southern stream short wave
trough moving well off the middle Atlantic coast on Monday with the
other being the large upper low dropping southeastward across the
Great Lakes and Ohio Valley with a few small short waves embedded
A long look at deterministic and ensemble data overnight reveals
a consensus that favors the southern stream low being too far out
to sea on Monday and Monday night for a significant impact on our
area. All of the 50 European model (ecmwf) ensemble members are tightly clustered
around a surface low track well southeast of the 40/70 benchmark.
This supports the 00z deterministic runs of the European model (ecmwf) and GFS.
Therefore a big impact from this low is not expected.
However...our region of northern New England does get into a col
region Monday afternoon and night. This will present a broad
region of frontogenesis and weak forcing for ascent which will
likely result in a fairly broad area of light snow
developing. Light snow first develops along the coast and across
southern New Hampshire by late Monday afternoon...then spreading inland
Monday night. This may result in 1 to 3 inches of snow through
that time frame.
The Tuesday and Wednesday time frame paints a more uncertain
picture as model and ensemble spread increases. A large and deep
upper trough encompassing much of the real estate east of the
Mississippi River by Tuesday morning and it/S associated short
wave troughs will move toward the East Coast.
Most deterministic models and ensemble members agree that surface
low pressure will develop as a result...but where and how strong
is the problem. Much of the 00z European model (ecmwf) ensemble members are
scattered all over the place by Tuesday night with the best
clustering of low centers east of it/S 00z deterministic run.
However...several of the 50 ensemble members do develop strong
cyclogenesis close enough to the coast for at least a moderate-
impact snowstorm somewhat like the 00z deterministic run. This
sentiment is shared by a small number of GFS ensemble members.
Therefore as of this writing...will handle the situation with
high chance probability of precipitation Tuesday night...mainly along the coastal plain
based on the remaining wide range of possibilities. In a
nutshell...we are not out of the Woods yet as far as a possible
impactful snowstorm GOES...centered around late Tuesday and
Tuesday night. However...the most likely scenario remains
something of lower impact. Will continue to monitor trends.
Thereafter...the 00z GFS and European model (ecmwf) try to drop the polar vortex on
top of US next weekend...at least for a short time. If that
verified we would probably see the coldest weather of the season.
But we/ll see.
Aviation /15z Saturday through Wednesday/...
short term...VFR conditions. Scattered MVFR after 21z in any
mountain snow showers. Areas of MVFR after 06z in mountain snow
showers with local IFR possible in mountain snow squalls.
Long term...MVFR conditions possibly develop on Monday in light
snow...with could continue on and off through Tuesday. A coastal
storm will be possible later Tuesday and Tuesday night with
associated lower conditions in snow...but confidence is quite low
at this time.
short term...winds and seas should build later today in
strengthening southerly flow ahead of the cold front with small
craft conditions expected outside the bays...with conditions
Long term...small craft conditions are expected much of the long
term period...mainly Sunday night through Wednesday. Gales will be
possible during this time as well...mainly later Sunday night
through Monday. Low pressure will likely affect the waters once
again around Tuesday night...but strength and track is uncertain
at this time.
Marine...Small Craft Advisory until 6 am EST Sunday for anz150-152-154.
Near term update... Kimble