Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Caribou ME
1251 PM EST Sat Nov 22 2014
strong high pressure will build south of the area this afternoon
and move east on Sunday. Meanwhile...an weak upper level disturbance
will move across far northern Maine through this evening. Strong
low pressure from the Great Lakes will approach later Sunday and
then move northwest of the region on Monday.
Near term /through tonight/...
1230 PM update...periods of light snow continue across The Crown
of Maine in response to the upper disturbance moving across
Quebec. At the surface is a weak warm front west/some low level
convergence per the 16z analysis. The best convergence was across
far northwest and north Maine. Kept likely pops(60%) right across the
northern border for the remainder of the afternoon and then
dropped the probability of precipitation back as one heads south. Hrly temperatures were
adjusted more across the central and downeast to bring them up a
few degrees from the previous package.
For tonight...the high moves far enough east that we'll start to
see some warm air advection around the backside. As such, lows
will be during the evening, with temperatures holding steady or
rising overnight. Don't expect much warm advection precipitation outside
of some showers over the higher elevations of the northwest.
Generally expect this to fall as snow but with warmer air moving
over colder air at the surface, can't rule out some pockets of
freezing rain late tonight. Snow accumulation will be light, with
little to no ice accretion. For our coastal area...another weak
disturbance will move over the Gulf of Maine, bringing the slight
chance of rain showers to the region. A bit of snow may mix in
away from the immediate coast, but don't anticipate any
Short term /Sunday through Tuesday/...
whats left of moisture from an initial shortwave moving east into the
Maritimes will be exiting southeast ME Erly Sun morning. This will likely
leave low cldnss across especially northern portions of the forecast area through the
remainder of sun...with moderating daytm temperatures. After a period of prtl
clearing sun evening...clouds will increase by late Sun night...with another
band of light precipitation by Erly Monday morning. For now...with slowly rising
temperatures expeceted late Sun night...precipitation type is expeceted to be very light
rn...but we cannot completely rule out patchy light freezing rain in a few
colder northern valley lctns...but to Erly at this time to commit to this precipitation
type...especially given only chance probability of precipitation.
Aftwrds...a warm occlusion rn band crosses west-southwest to east-northeast across the
forecast area late Monday morning through the afternoon. Forecast rn amounts of a quarter inch+
suggests going with categorical probability of precipitation for most of the region with
the passage of this band. Temperatures and winds will steadily climb
during the day...with temperatures likely reaching a maximum after dark across
much of the region behind the occlusion...where both 925 mb temperatures
and mixing of winds aloft result in better mixing and steeper low level
Overnight temperatures will continue very mild into the overnight with any left over
shower activity exiting east of the forecast area during the evening. A msly dry cold
front will then cross the region late Monday night...resulting in
falling surface temperatures across the region by daybreak Tuesday. Subsequently
hi temperatures Tuesday is uncertain...especially across the northwest half of the forecast area if
enough cold air arrives by daybreak to block the normal diurnal
rise of temperatures.
Long term /Tuesday night through Friday/...
whats left of a shortwave from central can will bring more low SC cldnss
to northern portions for the forecast area Tuesday night with flurries and possible snow
showers...with most of the low level cold advcn passing north of the forecast area. Low
temperatures will be colder than Monday night...but likely still above normal
for this date.
After a break into Wednesday afternoon...cldnss will move S to north ahead of low
pressure moving NE from the southeast states. There is still some uncertainty
regarding how close to the new eng coast this low will track Wednesday
night and Erly Thursday morning. We did note that the stronger and further
west tracking 00z dtmnstc run of the European model (ecmwf) matched a few of the ens
member solutions from ystdy's 12 GFS ens run...but was not well
supported by the 00z GFS and 00z GFS ensm and most comprising
members. For now...we did raise probability of precipitation a little across all...xcpt
the far northwest portion of the forecast area Wednesday night into Erly Thursday...with chance probability of precipitation over
the central ME Highlands and the far NE and likely probability of precipitation over downeast
and east central portions of the forecast area. Temperatures should be cold enough for all snow
by late evening for inland areas...with rn chgng to snow late Wednesday night
over downeast coastal and southeast portions of the forecast area. Given the wide range
of tracks and intensities withe this system...we will hold off
mentioning this system in the severe weather potential statement at this time.
Whatever the outcome of the low intensity and track Wednesday night...any
snow should end by middle morning Thursday across the southeast half of the forecast area...with
perhaps breaks in the cldnss by Thursday afternoon. Another shortwave could bring
more cldnss and snow showers to the region Thursday night into Friday morning.
Temperatures should return to at to below normal by the late week.
Aviation /18z Saturday through Thursday/...
near term: mainly VFR conditions expected through the period. The
exception will be kfve and perhaps kcar, where MVFR in light snow
will be possible, mainly this afternoon.
Short to long term: MVFR clgs expeceted across northern taf sites sun into
sun evening...while downeast sites hold VFR. All sites then lower to
IFR clgs and rn late Sun night into Monday morning...continuing through the afternoon
then improving to VFR all sites Monday night...continuing through Wednesday.
near term: a Gale Warning has been issued for the outer waters for
this afternoon through tonight. A 35-45 knots low level jet will cross
the Gulf of Maine during this period, and given the relatively warm
waters, expect gusts around 35 kts to occur. For Penobscot Bay,
gusts will only be around 30 kt, so a small craft is in effect for
Short to long term: we expect Small Craft Advisory winds and seas sun...with waves
continuing to build Sun night through Monday as winds increase to near gale
force gusts by Monday afternoon. Aftwrds...both winds and seas will only
slowly subside Monday night through Tuesday. After a break Tuesday night into Wednesday
morning...uncertainty of winds and waves at this time for Wednesday Wednesday afternoon into
Thursday morning depending on the track and intensity of a coastal low
moving NE from the southeast states.
Marine...Small Craft Advisory until 4 am EST Sunday for anz052.
Gale Warning until 4 am EST Sunday for anz050-051.