Special Weather Statement, NWS Great Falls, MT

Area Forecast Discussion
National Weather Service Great Falls MT
1158 PM MDT Thu Aug 31 2023

...AVIATION SECTION UPDATED...

.SYNOPSIS...

High pressure will build into the Plains of Montana today and
tomorrow, bringing a gradual weakening of the winds through the
evening hours. This high pressure system will keep us mostly quiet
through the weekend, with just a few rain showers and
thunderstorms across Southwestern Montana as temperatures
gradually warm through Saturday.

&&

.UPDATE...

The forecast is working well; therefore, no updates are made, at
this time.
- Fogleman

&&

.DISCUSSION...

Winds remain a bit breezy this afternoon as a low pressure system
gradually pulls away from the area and high pressure begins to
work its way into the area. With this high pressure system moving
in, and sinking air on the back side of the low pressure, the few
morning showers that we had this morning have dissipated, leaving
us with mostly sunny, albeit hazy, skies for the afternoon.

The aforementioned high pressure system will linger about the area
through the weekend, keeping us relatively calm wind wise across
the plains, though Southwesterly flow aloft may be able to sneak
to the surface during the afternoon across Southwestern Montana.
In addition to the gusty afternoon winds in the southwest, this
flow will also allow sufficient moisture to creep into the area to
allow for a few isolated to scattered (10-40% coverage) showers
and thunderstorms to develop, especially near the Montana/Idaho
border Friday and Saturday. Temperatures will also gradually
climb through the next few days, the valleys of the Southwest
seeing highs reach the low 80s, with the Plains reaching the low
90s on Saturday.

As we head into the day on Sunday, expect clouds to increase
across the area as an upper level trough begins to push into the
area. As this trough pushes through, we'll see some more in the
way of rain showers overspread Southwestern Montana Sunday
evening, with a few light rain showers reaching the plains by
Monday morning. Precipitation amounts between Sunday evening and
Monday should generally be around a half inch to an inch south of
I-90 with locally higher amounts in some of the higher terrain.
Further north, amounts will gradually taper off as you go further
north, with just a few hundredths expected across the plains.

Beyond Monday, the upper level flow will turn zonal/Westerly,
which will generally result in a few chances for rain showers
through midweek with generally light winds and seasonable
temperatures.
Ludwig

&&

.AVIATION...
1158 PM MDT Thu Aug 31 2023 (01/06Z TAF Period)

Note: The National Weather Service Great Falls Weather Forecast
Office manages the following TAFs: KCTB, KHVR, KGTF, KLWT, KHLN,
KBZN, KEKS and KWYS.

A broken line of light showers and a rumble of thunder or two are
moving northward though Southwest Montana tonight. Little if no
rainfall is expected, but these showers may bring variable and gusty
winds up to 20 kts to the southwest terminals through 09 or 10Z.
Otherwise, quiet conditions are expected through Friday morning with
some light haze for the far northern terminals. The aforementioned
shortwave energy will also increase southerly winds to the 10 to 30
kt range in the southwest Friday afternoon, mostly for KEKS and
KWYS. Widely scattered showers and a few thunderstorms are expected
after 20Z, mostly south of I90. - RCG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  49  83  55  90 /   0   0   0   0
CTB  45  77  51  87 /   0   0   0   0
HLN  51  88  58  90 /   0   0  10  10
BZN  47  85  55  86 /   0   0  10   0
WYS  39  73  44  70 /  20  20  30  20
DLN  45  80  50  79 /   0  10  20  10
HVR  51  88  54  94 /   0   0   0   0
LWT  49  85  56  88 /   0   0   0   0

&&

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

http://www.weather.gov/greatfalls

Special Weather Statement
National Weather Service Great Falls MT
1207 AM MDT Fri Sep 1 2023

MTZ327>330-010645-
Ruby Mountains and Southern Beaverhead Mountains MT-
Gallatin and Madison County Mountains and Centennial Mountains MT-
Northwest Beaverhead County MT-
Beaverhead and Western Madison below 6000ft MT-
1207 AM MDT Fri Sep 1 2023

...Strong wind gusts from showers and weak thunderstorms will impact
portions of southwestern Madison and Beaverhead Counties through
1245 AM MDT...

At 1204 AM MDT, Doppler radar was tracking showers and thunderstorms
along a line extending from 18 miles south of Jackson to 8 miles
west of Lima. Movement was northeast at 35 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Dillon, Lima, Monida, Dell, Grant, Bannack Pass, Melrose, Lakeview,
Bannack, Snowline, Glen, Beaverhead Rock State Park, Polaris, Clark
Canyon, Bannack State Park, and Monida Pass.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4445 11300 4477 11313 4482 11324 4479 11335
      4490 11348 4503 11344 4512 11352 4512 11354
      4568 11271 4563 11270 4568 11257 4456 11170
      4451 11182 4456 11187 4452 11211 4457 11229
      4445 11239 4450 11274 4444 11283 4436 11285
TIME...MOT...LOC 0604Z 239DEG 44KT 4512 11329 4459 11275

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

RCG