Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
551 am EST Monday Mar 2 2015
breezy but relatively mild weather expected today as low pressure
tracks northeast across the maritime provinces. High pressure
builds in from the west tonight and shifts offshore by Tuesday
afternoon. Low pressure will swing through southern Canada
Tuesday night pushing a warm front north across the region...and
producing a period of snow and mixed rain or snow along the coast.
As the low shifts to our north...it will drag a cold front through
the region late Wednesday. High pressure will build in from the
west Thursday and will crest over the region on Friday.
Near term /until 6 PM this evening/...
550 am...made some updates to probability of precipitation...mostly to cover the weak
area of snow over eastern zones...that seems to be originating from some
low to middle level convergence...weak 850mb front...and weak surface wind
boundary. 00z NAM-dng seems to have the best handle on this as it
builds a little over the next hour or two and then shifts eastward.
Otherwise upslope snow looks to continue over the mountains this
morning...as weak 850 mb wave moving through now...and then will see
500mb follow later this morning.
Previously...for the most part...the final bit of light snow
associated with the offshore surface low will be exiting the eastern zones
by 09z. 500 mb trough axis is hanging back and will cross the northern
County Warning Area between 15 and 18z. This will bring a round of shsn to the
mountains and will be enhanced by upslope later this morning into at
least the first half of the afternoon. Actually...mesoscale models also
suggest a few shsn or flurries across the eastern zones around midday
with this feature as well....although don't really expect any
accums here. However in the upslope areas could see a few inches
in the locally favored areas. Despite all the cold this
year...upslope snow event have been quite limited as most of these
500mb systems have been deep or closed off troughs which drag all
the energy to our east and pull dry air in quickly behind the main
system...leaving very little in the way of dynamics or instability
to enhance the upslope.
On the coastal plain...this trough will keep the clouds
around...at least for M/cdy conds through the morning...before the
winds kick in and the downslope begins which should clear things
out during the afternoon. Should warm up nicely here as
well...with highs in the middle-upper 30s.
Short term /6 PM this evening through 6 PM Tuesday/...
the [pres gradient holds up through the evening hours...and the
breezy conds will continue through the first part of the evening
before they start to diminish as the high moves to our S. Colder
air will move in and should see some of the sheltered decouple
for the second half of the night...with lows in single digits below
zero in the north...and single digits to around 10 above elsewhere.
On Tuesday the high will pass just to our S in the morning and
than shift off shore by late in the day. This will keep flow
light...and with middle-high clouds moving in from the next system
highs will be limited to the 20s. Precipitation will likely hold off until
after sunset...but a little light snow could break out in SW New Hampshire for
the evening commute.
Long term /Tuesday night through Sunday/...
in short...a continuation of below normal temperatures and no
heavy precipitation events. The models are in general agreement
on the long wave pattern well into next week. The western ridge
gradually flattens and moves onshore into the western half of the
Continental U.S....while we see lingering trofiness here in the east and
below normal temperatures...punctuated by periodic brief warm ups.
We begin the period with an impulse racing eastward from the
northern plains into New England. A quick overrunning event with
light mixed precipitation Tuesday night followed by a brief warm
up on Wednesday ahead of a cold front. Scattered upslope snow
showers follow for Wednesday night and Thursday. High pressure
builds east across the area Friday. A weak disturbance will drag
trailing warm and cold fronts across the region next weekend.
Another cold front will cross the area eraly next week.
Aviation /12z Monday through Friday/...
short term...could still see some MVFR through about sunrise...and
maybe lower in fog at kcon...but all locations should improve VFR
after sunrise...with the exception of khie...which could linger at
MVFR though today...and may go lower briefly is shsn. All
terminals should expect VFR tonight and Tuesday.
Tuesday night - Wednesday...MVFR with local IFR in light mixed precipitation.
Thursday...scattered MVFR in mountain snow showers.
short term...have extended the gales through the overnight
tonight...as the pressure gradient looks to hold a little
longer...especially east of Casco Bay. But as high pressure builds in
winds will diminish quickly early Tuesday morning. As the winds pick
up this afternoon and the temperatures drops this evening...look for another
round of light fz spray tonight into early Tuesday.
Tuesday night - Wednesday...gale force winds are possible.
Thursday - Friday...small craft winds and seas are possible.
Marine...Small Craft Advisory from noon today to 3 am EST Tuesday for
Gale Warning from noon today to 3 am EST Tuesday for anz150-