Special Weather Statement, NWS Great Falls, MT

Area Forecast Discussion
National Weather Service Great Falls MT
512 PM MDT Mon Aug 1 2022

...Aviation Section Updated...

.SYNOPSIS...

Hot, dry, and gusty condtions are expected across the Northern
Rockies today, which will raise the risk for heat related
illnesses and potential for rapidly spreading wildfires should one
start.

&&

.DISCUSSION...

Rest of Today through Tuesday...Upper level ridge of high pressure
extending into the NW US is being suppressed by an upper trough
moving into BC and will further collapse through Tuesday as the
trough progresses east across western Canada. Hot and dry
conditions persist into this evening across the area though mid
level moisture and clouds will increase in strengthening west to
southwest flow aloft. Scattered thunderstorm development should
progress through this afternoon across SW MT where greater mid
level moisture is already in place. Slight cooling aloft and an
upper level jet sags SE into western MT tonight in association
with the trough moving into BC. While only limited moisture moves
across central/north central MT tonight some high based showers
with virga is likely with a small risk of isolated thunderstorms
through this evening. Main impact from this is the potential for
gusty/erratic downdrafts though any lightning would also be a fire
weather concern with with the already critical wind and humidity.
Breezy winds with gusts 25-30 mph across much or north- central
and portions of central MT into this evening. Flow aloft continues
to increase through Tuesday as the upper trough moves further
into western Canada. Surface low pressure also develops late
tonight and moves east across the Canadian Prairies Tuesday. All
of this supports the expected windy conditions across much of the
area Tuesday with gusts of 30-40 mph likely across north- central
MT. Hoenisch

Wednesday through next Monday...upper level ridge will begin to
rebuild over the Northern Rockies on Wednesday and Thursday, but a
stronger H500 shortwave crossing over the Northern Rockies from
Thursday night through the day on Friday will once again break down
the ridge. High temperatures, while cooler than this past weekend
and today, will remain hot and in the upper 80s to 90s on Wednesday
and Thursday. These hot temperatures combined with continued breezy
and dry conditions, especially on Wednesday, will maintain elevated
fire weather concerns through at least Thursday. Temperatures will
then cool to near or below normal on Friday, remaining near to below
normal through the upcoming weekend. - Moldan

&&

.AVIATION...
512 PM MDT Mon Aug 1 2022 (02/00Z TAF period)

Isolated to scattered high-based showers and possibly a couple of
thunderstorms will move across the forecast area this evening
through the early overnight, with greatest coverage across southwest
Montana tapering off to the north. Gusty outflows will be possible
with any shower or thunderstorms that develop, even during the
overnight period. Gusty west winds develop Tuesday across the area,
with shower and thunderstorm chances more concentrated just south of
KBZN to KWYS, including KEKS. Smoke/haze from distant wildfires may
also impact slightly impact visibility at times.

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.

&&

.FIRE WEATHER...

Critical fire weather conditions expected across much of the area
this week as a belt of faster westerly flow aloft sets up across
the northern Rockies and MT. Strongest winds with gusts 30-40 mph
are expected Tuesday following the passage of Pacific cold front
late tonight. There is a small risk of isolated showers and
thunderstorms with the frontal passage tonight. Afternoon
humidity remains low (10-20%)through much of the upcoming week
with some improvement to overnight RH recoveries.

&&

.CLIMATE...

Record high temperatures are once again possible today across the
CWA, especially across Central Montana where readings are expected
to eclipse the century mark at numerous locations.

Additionally, Helena has already had 3 days in a row of 100+
temperatures and is forecast to reach 100+ today. Should Helena
reach 100 degrees today, it would tie the longest consecutive
streak of 100+ degree days in a row at 4. The record of 4 days in
a row was set from July 17 thru July 20, 2003.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  67  93  55  94 /  20   0   0   0
CTB  62  85  53  86 /  10   0   0   0
HLN  69  93  60  94 /  20   0   0   0
BZN  61  92  52  92 /  20  20  10   0
WYS  52  75  44  78 /  30  70  20  10
DLN  59  86  51  86 /  20  20  10  10
HVR  69  88  56  93 /  20   0   0   0
LWT  64  91  53  90 /  20  10   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until midnight MDT tonight Blaine...Broadwater...
Cascade...Central and Southern Lewis and Clark...Chouteau...
Eastern Glacier...Eastern Pondera...Eastern Teton...Fergus...
Gallatin...Hill...Jefferson...Judith Basin...Liberty...Meagher...
Southern Rocky Mountain Front...Toole.

Red Flag Warning until 9 PM MDT Tuesday Central and Eastern
Lewis and Clark National Forest Areas...Chouteau and Fergus
Counties...Eastern Glacier/Toole/Central/Eastern
Pondera/Liberty...Hill and Blaine Counties...Lewis and Clark
National Forest Rocky Mountain District-Rocky Mountain Front.

Red Flag Warning until midnight MDT tonight Gallatin National
Forest.

&&

http://www.weather.gov/greatfalls

Special Weather Statement
National Weather Service Great Falls MT
603 PM MDT Mon Aug 1 2022

MTZ008-015-020030-
Madison MT-Beaverhead MT-
603 PM MDT Mon Aug 1 2022

...Strong outflow winds will impact portions of Madison and
southeastern Beaverhead Counties through 630 PM MDT...

At 601 PM MDT, Doppler radar was tracking a cluster of showers and
thunderstorms from 8 miles southwest of Alder, or 14 miles west of
Virginia City, extending south to near Monida, moving east at 45 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Observed.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Virginia City, Ennis, Alder, Mcallister, Lakeview, Jeffers, Laurin,
Cameron, Raynolds Pass and Red Rock Pass.

This includes Highway 287 between mile markers 1  and 6 , and between
mile markers 1  and 65.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4454 11219 4474 11248 4538 11247 4564 11138
      4475 11138 4472 11140 4470 11149 4466 11147
      4464 11152 4458 11152 4454 11185 4456 11189
      4452 11210
TIME...MOT...LOC 0001Z 255DEG 37KT 4522 11221

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

CMC