Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Glasgow Montana
204 PM MST Thursday Nov 26 2015
Short term...for northeast Montana...tonight through Saturday...
period will be fairly quiet with temperatures rebounding closer to
Upper trough will be overtaken somewhat tonight by a strong upper
ridge over western Canada but not robustly as the trough closes off
over the Great Basin.
Without a strong system in the area and light winds expected, am
expecting local effects to have more control and thus models may
continue to perform fair at best. Case in point, what happened
last night with temperatures (models were too warm - by more than
10 degrees in some places).
Continued the idea that modeled temperatures are too warm and thus
kept them on the cool side of things. Mixing doesn/T look too good
either with 850 mb-surface lapse rates near zero Friday and Saturday.
A more interesting system looks to approach the area from the south
late Saturday. Tfj
Long term...Saturday night through Thursday...
Forecast challenges continue to revolve around the detached and
closed-off low pressure system well south of our region...which
still may play a part in influencing the weather for northeast
Montana late this weekend into early next week.
Models are still showing a fair amount of disagreement and
inconsistency to allow for little confidence in much of the
associated precipitation to reach far enough north into
northeastern Montana. As the upper low spins over the Great
Basin...numerous waves of energy and/or short-waves will pinwheel
around...which for US will approach from the south and southeast.
Unfortunately...by this time...the models slightly out of phase
with each other means significantly different results in the
sensible weather at the surface. A fair model consensus would
suggest good chances for our southeast zones late Sunday night through
Tuesday morning...but one outlier keeps US dry. Would like to see
this outlier look more like the remaining consensus before probability of precipitation
are increased to more than just a slight chance. For now...leaned
the forecast in that direction with that thinking which calls for
1 to 3 inches of snow for areas near and southeast of the Big
Sheep Mountains over that nearly 2-day period. Bmickelson
Previous long term discussion...the main weather feature of the
extended period will be the closed off upper low centered over the
Great Basin beginning to slowly drift northeast. Models continue
to have difficulty dealing with this large retrograde feature. But
as it moves towards north towards Montana it sends a cold front
into the area. The area will be under the influence of a large
Canadian ridge. Therefore this low will spread low clouds and
possibly light snow across the area Saturday night through Sunday
night. There remains much uncertainty since the 12z ec models
stays farther south and nemont stays dry and warmer. However the
00z ec solution changed significantly and now looks more like the
GFS. So this will still have to play out. In any case...will leave
slight chance probability of precipitation in the grids.
Models become murkier beyond the weekend. The ec again becomes
dry and warm...but not the GFS...which holds on to its cooler
ways. Later in the week an upper ridge is more likely to finally
bring in a warm front and milder temperatures. Scattered
An upper level ridge moves into the area later today to bring
mostly clear skies and light winds. The temperature difference
between the much colder air and the warmer surface of Fort Peck
Lake...not yet frozen over...may create some lake fog or some low
level lake clouds which may eventually impact kggw or kolf with
sudden IFR or worse conditions during the late night...overnight
and early morning hours. Confidence is not quite high enough to
include in a prevailing taf group at this time. Scattered/blm