Hail and Damaging Winds in Montana, July 1 to 6, 2023

Area Forecast Discussion
National Weather Service Great Falls MT
1140AM MDT Sat Jul 1 2023

.SYNOPSIS...

Breezy and gusty west winds are expected today over the plains
and valleys of Central and North Central Montana, with the
strongest winds expected along the Rocky Mountain Front. High
temperatures will peak in the 80s to mid-90s across the Northern
Rockies, with widely scattered to numerous showers and
thunderstorms possible this afternoon and early evening south of
the Montana Hwy 200 corridor. A cold front will drop south across
the Northern Rockies on Sunday, cooling some location by 5 to 15
degrees.

&&

.UPDATE...

Inherited forecast is performing nicely; therefore, no updates are
made, at this time.
- Fogleman

&&

.DISCUSSION...

Today through Sunday...Fast, zonal flow aloft over the Northern
Rockies through tonight will help to maintain above to well above
normal temperatures, breezy and gusty west winds, and low relative
humidity values across the Northern Rockies. While high wind
criteria wind speeds and gusts are not currently expected through
this evening, NBM probabilistic data does supports a 70% or greater
chance of seeing wind gusts in excess 41kts across portions of the
East Glacier Park Region, Southern Rocky Mountain Front, Northern
and Southern High Plains, and Eastern Glacier/Western Toole/Central
Pondera Counties. High temperatures will climb an additional 2-5
degrees (from Friday) across Southwest through North Central Montana
thanks to these breezy and gusty west winds, with most locations
peaking in the 80s to mid-90s. Hottest temperatures today are
expected over the plains of Central and North Central Montana east
of the I-15 corridor. While widely scattered to numerous showers and
thunderstorms are possible this afternoon and early evening south of
the Montana Hwy 200 corridor, areas north of this corridor will
remain dry through tonight. A cold front will then begin to advance
south and across the Northern Rockies during the day on Sunday,
switching surface winds to the north and cooling some locations
across Central and North Central by 5 to 15 degrees.

Monday through Tuesday (Independence Day)...cluster analysis on
Monday supports and amplified longwave ridge over the Eastern
Pacific points north to over the Northwest Territories in Canada,
with a positively tilted longwave trough orientated from over
Central Canada points southwest into portions of the Pacific
Northwest and Northern Rockies. By Tuesday, the longwave ridge over
the Eastern Pacific slides slightly eastward to near the western
seaboards of the CONUS, with northwest flow remaining in place over
the Northern Rockies as the positively tilted longwave trough begins
to lift northeast to near Hudson Bay. An embedded shortwave dropping
southeast within the downstream side of the ridge axis from Monday
night and through the day on Tuesday will move over the Northern
Rockies as the main longwave trough axis slides east of the region,
providing support for widespread precipitation across the Northern
Rockies over the timeframe, especially to Central Montana. Numerous
reinforcing cold fronts on Monday and Tuesday will usher in
progressively cooler/below normal temperatures, with high
temperatures on Tuesday being well below normal and in the upper 50s
to near 70 degrees across Southwest trough North Central Montana.
Snow levels late Monday night and into the day on Tuesday could fall
to as low as 8000 feet across Central Montana, which could lead to
some minor snow accumulations across the higher peaks.

Wednesday through next Saturday...high temperatures slowly begin to
moderate closer to normal as the upper level ridge over the Eastern
Pacific attempts to build east to over the Northern Rockies,
remaining just to the west over the Pacific Northwest and placing
the Northern Rockies beneath unsettled northwest flow aloft. This
unsettled northwest flow aloft pattern will provide for daily
chances for isolated to scattered showers and storms across
Southwest through North Central Montana, with the best coverage of
showers and storms being over the higher terrain. - Moldan

&&

.AVIATION...
1140 AM MDT Sat Jul 01 2023 (01/18Z TAF Period)

Increasing winds aloft will result in gusty surface winds across the
area today, especially at KBZN, KGTF, KHLN, KCTB, and KHVR. While
winds will result in some areas of mountain wave turbulence, expect
VFR conditions to prevail. Main concern this afternoon will be some
TSRA activity across SW MT. While most of this should be isolated
pop up SHRA/TSRA, a more organized complex of storms is on track to
reach KHLN around 1820z, and will bring a period of gusty winds and
rain to the terminal. Ludwig

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  91  57  84  48 /  10   0   0   0
CTB  89  55  78  43 /   0   0  10  10
HLN  90  55  89  52 /  20   0   0   0
BZN  85  50  87  49 /  40  30  10  10
WYS  75  40  77  39 /  60  70  20  20
DLN  82  48  85  46 /  40  20  10  10
HVR  96  59  81  48 /   0   0  10  30
LWT  84  54  81  47 /  10  10  20  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

http://www.weather.gov/greatfalls

Special Weather Statement
National Weather Service Great Falls MT
900 AM MDT Sat Jul 1 2023

MTZ301>303-307-308-011800-
East Glacier Park Region-Northern High Plains-
Eastern Glacier, Western Toole, and Central Pondera-
Southern Rocky Mountain Front-Southern High Plains-
Including the cities of East Glacier Park, Kiowa, Babb,
Saint Mary, Marias Pass, Logan Pass, Browning, Heart Butte,
Dupuyer, Cut Bank, Ethridge, Santa Rita, Rogers Pass, Bynum,
Choteau, and Pendroy
900 AM MDT Sat Jul 1 2023

...Strong Cross Winds...

Westerly winds steadily increase through the morning hours today
along the Rocky Mountain Front, becoming sustained between 20 to
30 mph with gusts as high as 45 to 55 mph from this afternoon through
early this evening. Travelers, especially on United States
Highway 89 between Choteau and the International Boundary and
United States Highway 2 between Cut Bank and Marias Pass, should
be prepared for strong cross winds. High profile vehicles or those
pulling trailers should be especially cautious and know their
vehicles limits when traveling this afternoon. Additionally, those
recreating in the higher terrain of the Bob Marshall Wilderness
and Glacier National Park should be prepared for strong and gusty
winds when navigating across ridgelines or near saddles.

Fogleman

Special Weather Statement
National Weather Service Great Falls MT
1146 AM MDT Sat Jul 1 2023

MTZ315-316-319-320-322>324-011845-
Helena Valley MT-Elkhorn and Boulder Mountains MT-
Missouri Headwaters MT-Big Belt, Bridger and Castle Mountains MT-
Upper Blackfoot and MacDonald Pass MT-Canyon Ferry Area MT-
Gates of the Mountains MT-
1146 AM MDT Sat Jul 1 2023

...Strong thunderstorms will impact portions of southeastern Lewis
and Clark, northwestern Broadwater, northwestern Meagher and northern
Jefferson Counties through 1245 PM MDT...

At 1146 AM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from 14 miles south of Lincoln to 10 miles east of
Garrison to near Warm Springs. Movement was east at 40 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Helena, Boulder, East Helena, Montana City, Basin, Wickes, York,
Rimini, Alhambra, Corbin, Spring Meadow Lake State Park, Austin,
Elkhorn State Park, Marysville, Winston, Clancy, Canyon Creek, Black
Sandy State Park and Jefferson City.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with these storms and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4633 11254 4633 11246 4641 11232 4662 11230
      4666 11233 4666 11241 4670 11242 4670 11253
      4683 11253 4688 11162 4649 11158 4604 11170
      4610 11248 4618 11251 4618 11257 4624 11260
TIME...MOT...LOC 1746Z 270DEG 34KT 4675 11264 4650 11261 4620 11269

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

MPL

Special Weather Statement
National Weather Service Great Falls MT
1204 PM MDT Sat Jul 1 2023

MTZ301>303-307-308-012115-
East Glacier Park Region-Northern High Plains-
Eastern Glacier, Western Toole, and Central Pondera-
Southern Rocky Mountain Front-Southern High Plains-
Including the cities of East Glacier Park, Kiowa, Babb,
Saint Mary, Marias Pass, Logan Pass, Browning, Heart Butte,
Dupuyer, Cut Bank, Ethridge, Santa Rita, Rogers Pass, Bynum,
Choteau, and Pendroy
1204 PM MDT Sat Jul 1 2023

...Strong Cross Winds...

Today, strong gusty westerly winds occur along the Rocky Mountain
Front. Sustained winds between 20 to 30 mph with gusts as high as
45 to 55 mph are forecast for this afternoon through early this
evening. Travelers, especially on United States Highway 89 between
Choteau and the International Boundary and United States Highway
2 between Cut Bank and Marias Pass, should be prepared for strong
cross winds. High profile vehicles or those pulling trailers
should be especially cautious and know their vehicles limits when
traveling this afternoon. Additionally, those recreating in the
higher terrain of the Bob Marshall Wilderness and Glacier National
Park should be prepared for strong and gusty winds when
navigating across ridgelines or near saddles.

Fogleman

Preliminary Local Storm Report
National Weather Service Great Falls MT
1220 PM MDT Sat Jul 1 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1215 PM     Tstm Wnd Gst     11 W Helena             46.58N 112.25W
07/01/2023  M51 MPH          Lewis and Clark    MT   Trained Spotter

&&

ML