Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Glasgow Montana
1159 am MDT sun Jul 5 2015
Short term...for northeast Montana...today through Tuesday...
Quick update to issue lake Wind Advisory for northwest winds of 15
to 25 miles per hour which were observed on the lake. Scattered
busy visual satellite imagery and lightning detection network
show the thunderstorm activity near the cold front has moved out
of northeast Montana this morning. However upstream...rain showers
continue. So went ahead and changed weather type to coverage. Also
revealed is the strong low pressure center in northern Manitoba
that is driving this system...which will maintain a northern
surface breeze to keep temperatures in the cooler than normal
range. Slightly adjusted temperatures based on biasadj. Finally
off to the west the upper flow has entrained additional smoke from
wild fires in British Columbia and Washington state. With visibilities ranging
from 3sm to 7sm this morning...went ahead and added smoke to the
weather grids for today. Scattered
upper trough pushing into northern Montana this morning with showers
and thunderstorms ahead of it across eastern Montana. Showers
expected to continue today as the trough rotates through the region
before gradually tapering off from the northwest this evening.
The upper trough will also bring cooler air into the region with
maximum temperatures about 20 degrees cooler. Cold air advection
could also aid in mixing winds for breezy conditions mainly this
morning...but not expected to exceed lake wind criteria.
Dry but continued cool conditions anticipated for Monday as high
pressure slides across Montana. As the high moves into the
northern plains on Tuesday...a weak front drops out of Canada. A
few thunderstorms are possible in the vicinity of this front
during the afternoon. Ebert
Long term...Tuesday night through Sunday...
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.
Smoke: smoke from Canadian wildfires will continue to cause off
and on reductions in visibility to 3-5 sm at times.
Showers: scattered to widespread showers will continue into the
evening hours. Visibility may be reduced in -ra in stronger showers...but
ceilings will remain VFR. Dry conditions and partial clearing are
expected late tonight into Monday.
Area winds: north-northwest at 5 to 20 kts Gilchrist
lake Wind Advisory until 9 PM MDT this evening for Fort Peck
Lake for central and southeast Phillips...central and southern