Heat Advisory 5, NWS Glasgow, MT

Area Forecast Discussion
National Weather Service Glasgow MT
335 PM MDT Fri Jul 2 2021

.DISCUSSION...
The record-threatening heat will continue for one more day before
temperatures begin to trend downward, beginning on Sunday. There
should be a slight chance of showers/storms in portions of the CWA
beginning on Sunday night and continuing through Tuesday as well
as noticeably cooler temperatures. By midweek, temperatures begin
to trend back up with 100s possible again.

Continuing Heat (tonight through Sunday)...
The ridge that's been dominating the West's weather continues to
shift to the east. Northeast Montana is still in the ridge's
influence Saturday night. At the surface, a "cold" front--which
is more like a dryline with lower dew points on the "cold" side of
the front along with a shift in wind direction--passes through the
area on Saturday. Winds will be more northwesterly on Saturday and
be gustier than they were today, which will enhance the fire
weather danger (see the "Fire Weather" section below). There
should be an increase in cloud cover on Sunday afternoon as a
chance of showers/storms begins to move in from the south.

Cooler and Unsettled (Sunday night through Tuesday night)...
Disturbances begin to move through the region Sunday night and
Monday as the ridge tries to re-establish itself near the West
Coast. This will be our best shot at seeing precipitation in the
foreseeable future, but wetting rains aren't expected except for
the few spots that do get rain. Temperatures will be noticeably
cooler, especially in the northeast corner of the CWA on Tuesday,
which is also where the best rain chances are on Monday.

Heat Returns (Wednesday and beyond)...
Upper level ridging re-establishes over the West mid to late week,
with operational models developing an impressively strong upper
high over the Desert Southwest late week. Northeast Montana will
be at the top of the ridge, so our temperatures will begin to take
off once again.

97

&&

.AVIATION...
FLIGHT CATEGORY: VFR.

LLWS: Potential for some LLWS at KGDV after midnight tonight from
the SW around 35 kts about 2kft AGL.

WINDS: SE 10-20 kts with higher gusts through the evening, then
becoming light and variable overnight. Winds become more W-NW
10-20 kts on Saturday and Saturday evening.

DISCUSSION: Pleasant flying weather will continue through the TAF
forecast period. Upper level ridging will begin to shift slightly
over the weekend, with the axis of the ridge extending from the
Dakotas to the Southern Plains. With the heat and instability in
place this afternoon and evening, there's a slim chance for a
stray shower or thunderstorm, which the main issues being gusty
variable winds and lightning.

97

&&

.FIRE WEATHER...
Relative humidity values should begin to recover this evening, so
the Red Flag Warning will be allowed to expire at 9 pm for the
whole CWA. Fuels, however, remain dry.

On Saturday, a dry frontal boundary will move through the region
bringing a shift in wind direction and a drop in dew points (and
relative humidity values as a result). This combination will lead
to a continuation to the elevated fire danger into Saturday. The
meteorological setup actually looks greater for hitting red flag
criteria than today with the lower humidity values and higher
winds. Went ahead and extended (issued) a Red Flag Warning for
Fire Weather Zones 122, 136, and 137 as a result. In Zone 122, the
main risk will be in Wibaux and Prairie Counties, the southern
half of Dawson County, and the southern third of McCone County.

There isn't really a widespread wetting rainfall in the CWA in
the forecast period, and late next week could also see at least
elevated fire weather conditions.

97

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 9 PM MDT Saturday for Central and
Southeast Phillips...Central and Southern Valley...Daniels...
Dawson...Eastern Roosevelt...Garfield...McCone...Northern
Phillips...Northern Valley...Petroleum...Prairie...Richland...
Sheridan...Southwest Phillips...Western Roosevelt...Wibaux.

Red Flag Warning until 9 PM MDT this evening for MTZ122-134>137.

Red Flag Warning from 10 AM to 9 PM MDT Saturday for
MTZ122-136-137.

&&

weather.gov/glasgow