Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Glasgow Montana
725 PM MDT sun Jul 5 2015
Short term...for northeast Montana...tonight through Tuesday...
changes to the forecast were first focused around increasing probability of precipitation.
Radar trends across the region are still holding strong with
scattered showers across the southern sections of the County Warning Area. Models
are pointing towards the remainder of this activity moving into
the Yellowstone activity during the early morning hours before
exiting entirely by the late morning. Second focus was on winds
which are quickly dying off this evening. Updating the grids with
the latest mesoscale data clearly pointed towards eliminating the
lake Wind Advisory as everything calms down. The final item of
focus was on visible satellite which is still showing haze across
the region from the smoke of Saskatchewan. Local ASOS observation have
the haze down to around 5 to 8 sm. Haze was put in through noon
Fires with continuous smoke billowing out of them are also
still evident over northern Saskatchewan on visible satellite...
this will force a rethinking of these grids overnight and may
extend haze throughout the short term with the overnight package.
Previous short term discussion...
cool conditions will continue tonight and Monday as the base of a
trough extension from the Hudson Bay low passes through
northeast Montana. Thickness heights drop to around 555dm while
700mb temperatures fall slightly below 0c. So with cold air advection...lows
tonight will range from the middle 40s to the middle 50s. Also the last
of most the associated rain will pass through the area tonight...
mainly south of the Missouri River. Monday morning might see a few
isolated showers...but conditions become dry by afternoon.
The broad upper trough over most of Canada will maintain
northwesterly to zonal flow over Montana. High pressure over the
far west will begin to weaken to influence of the trough for
northeast Montana. So expect temperatures to begin to creep back
to near normal on Tuesday. However Tuesday afternoon the Canadian
low sends another cold front south into nemont. This front reaches
the international border by 00z Wednesday. Therefore a few storms could
be initiated late afternoon.
Long term...Tuesday night through Sunday...
going forecast was in decent shape as described below. No changes
were made for the afternoon package. Gilchrist
Previous long term discussion...
synoptic set up... a large broad trough extends from the Great
Lakes over to the high plain of Wyoming and Montana. A large hot
high pressure ridge run up from the Desert Southwest through the
Pacific northwest and into British Columbia. Off the coast of
California sets a closed low.
Tuesday night through Friday... these periods will be dry with
only isolated activity in the afternoon/evening hours if any at
all. Conditions should slowly warm through this grouping as the
ridge to the west thickens and fills into Montana by Thursday.
The apex of the ridge should arrive by Friday. Confidence is
is near normal during this time frame.
Friday night through Sunday night... apex of the ridge will
topple over with a shortwave and may destabilize the atmosphere for
showers and thunderstorms again. Conditions may cool slightly and
a possible shortwave or two could arrive at later during these
periods. Confidence is slightly below average due to model
uncertainty behind the ridge axis in the destabilized area. Gah
flight category: mainly VFR...but some MVFR mixed in at times due to
smoke from Canadian fires.
Showers: scattered showers may briefly affect kgdv this evening.
Otherwise...dry conditions and partial clearing are expected late
tonight into Monday.
Winds: light north-northwest at 5 to 10 kts. Tfj/Gilchrist