Area forecast discussion
National Weather Service Glasgow Montana
300 PM MDT Tuesday Jun 18 2013
Short term...for northeast Montana...tonight through Thursday...
storms are beginning to fire up along the central Montana
Mountains this afternoon. These storms will push to the north and
northeast and could move into northeast Montana this evening and
overnight. Thus kept mention of isolated showers in for the
afternoon and evening. Brisk southeast winds will continue
overnight in response to a developing surface low over central
Montana. With southeast winds continuing into Wednesday
evening...the lake Wind Advisory looks on track through midnight
Wednesday night. A nocturnal storm or two can not be ruled out
thanks to weak qg forcing and midlevel instability over the north
and west.
Wednesday gusty low level southeast flow will continue to advect
in Gulf moisture out of the Great Plains...adding to the already
excellent surface based instability of 3000 j/kg Wednesday
afternoon. With that said...shear looks a bit marginal over the
eastern 2/3rds of northeast Montana...and may well help limit the
threat for severe storms.
Still thinking storms will fire Wednesday afternoon over the central
Montana Mountains...drifting northeastward into the area through
the afternoon and evening hours. A convective complex will likely
develop...impacting the north with heavy rainfall through the
overnight hours Wednesday night/Thursday morning. Gusty southeast
winds will switch to the west behind the associated surface front
late Wednesday night.
By midday Thursday the complex will have exited the area...but
with the upper trough overhead and lingering low level moisture
can not rule out an isolated shower or thunderstorm. Temperatures
will be cooler...in the middle 70s to low 80s. Gilchrist
Long term...Thursday night through Tuesday...
only minor tweaks were made to the extended forecast. The long
range forecast remains on track with an upper closed low across
the Pacific northwest and northeast Montana under southwest flow
aloft beginning on Thursday night. Pulses of shortwave energy
propagating around this upper low will lead to possible showers
and thunderstorms each day through the weekend. Both the 12z
European model (ecmwf) and GFS solutions carry a couple of particularly vigorous
shortwaves through the area during the weekend. There should be
plenty of available moisture with low level southeasterly flow in
place and so raised probability of precipitation from the Friday night through Sunday time
period...and then tapered down precipitation chances from west to
east as the upper level energy pulls out of the forecast region by
Sunday night.
Monday and beyond...kept slight chance probability of precipitation in the grids for
now...but model guidance indicates that southwest flow aloft
across the County Warning Area should transition into more of a ridging pattern
sometime during the middle portion of the week. This should
promote large scale subsidence and a drying pattern.
Additionally...this may allow for a moderation in temperatures and
so trended temperatures warmer toward the middle of the week. Maliawco
Previous long term discussion...
synoptic set up... long term begins with a dome of heat over the
Desert Southwest and a ridge spurring off across Colorado... the
Central Plains and upper Mississippi Valley. A large trough has
embedded itself into the Pacific northwest. Northeast Montana is
wedged between these two airmasses in southwest flow aloft. A weak
ridge also runs from southern Saskatchewan through northern
Alberta and into norther Alaska.
Thursday night through Saturday night... the core of the closed low
to the west is expected to drift onto the High Plains and will
cool temperatures down for awhile allowing for a chance of showers
and thunderstorms each afternoon and evening.
Sunday Onward... models are having problems decided what to to do
with this low once its over the High Plains. Consistency from run
to run and model to model seems fairly poor... decreasing confidence.
Currently models point toward the closed low kicking off toward
Ontario and a new ridge establishing itself right behind over
western Montana on Monday. This ridge should become a greater
influence with warming temperatures and decreasing chances for
thunder through middle week.
&&
Aviation...
an isolated shower or thunderstorm remains possible through
tonight but VFR conditions will continue to prevail at the
terminals. More widespread showers and thunderstorms are expected
to develop Wednesday and Wednesday evening. This may result in
reduced ceilings and visibilities. MVFR is therefore possible in
some of the heavier thunderstorms. Winds are anticipated to be from the
southeast through Wednesday from 10 to 20 kts with gusts as high
as 30 kts. Maliawco
&&
Glasgow watches/warnings/advisories...
lake Wind Advisory until midnight MDT Wednesday night for Fort
Peck Lake for central and southeast Phillips...central and
southern valley...Garfield...McCone...Petroleum.
&&
$$
Weather.Gov/Glasgow
