Scientific Forecaster Discussion
fxus65 kggw 230056
Area forecast discussion
National Weather Service Glasgow Montana
656 PM MDT Fri Jun 22 2018
have updated pops to reflect ongoing activity across the region.
The showers and storms out there this evening will continue to
diminish through early tonight with not much more than some
isolated showers overnight. By early tomorrow morning additional
showers and storms are expected to develop, with another round of
scattered storms likely for at least the eastern half of the County Warning Area.
Previous discussion: synoptic setup: hot high pressure has built
up over the Desert Southwest. A ridge extends out from this
airmass over western Montana and into Alberta. The weak spot over
Montana is where trough basins have been ejecting through the
ridge for the last half week. The first shortwave is over eastern
Montana and exiting to the west this morning. Another large trough
over the Gulf of Alaska extends down off the coast of British
Columbia with its base stepping onshore over the Pacific
Today through this evening: as the center of the shortwave moves
across the region scattered showers and thunderstorms will
continue in response to the general lift. In the afternoon there
is a small chance for severe but most of the forecast soundings
do not point towards enough organized shear to generate anything
of major significance.
Saturday through sunday: base of the trough over the pcnw will
break off and move across the weak point as well. However the bulk
of the showers are expected to steer south with the strongest
lift and may just lead to cooler days with light isolated to
scattered showers and very few thunderstorms. Meanwhile the ridge
will rebound over the pcnw and again rebuild into Alberta.
Sunday night into monday: ridge will progress across the area
warming up and drying out conditions for about a day making it
feel like full fledged Summer with highs in the upper 80s.
Monday night through wednesday: the large trough off the coast of
British Columbia will progress through the pcnw and bump the
large ridge out of the area. This clash of airmasses should lead
to jet streaks with thunder. Due to the large differences across
the gradient from one airmass to the other enough potential energy
will be present to generate severe weather and Pacific moisture
should add to this potential at times.
Wednesday night onward:models begin having a hard time staying in
sync. But due to the large hot airmass anchored to the south most
agree that a zonal to southwest flow pattern of some sort will
continue with scattered showers and thunderstorms possible each
flight cat: VFR-MVFR
Discussion: VFR will prevail generally through tomorrow. A few
MVFR ceilings or reductions in visibility are possible with any strong
thunderstorms that do occur early this evening or Saturday
afternoon. Expect periodic chances for showers and thunderstorms
through much of the weekend.
Wind: winds will continue to slowly turn to the northwest this
afternoon and evening, and should remain around 7-12 kts.
However, if any thunderstorms impact the vicinity of any of the
sites, expect winds to be gusty and erratic.