931
FXUS65 KGGW 160806
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
206 AM MDT Mon Sep 16 2024

.DISCUSSION...

KEY MESSAGES:

1) Warm temperatures will continue through Tuesday.

2) A few isolated thunderstorms possible today.

3) Slight Risk Category for Severe Thunderstorms Tuesday
afternoon.

4) Western zones could see a significant rain event Tuesday night
through Thursday morning. Lower amounts for eastern zones.


WEATHER PATTERN OVERVIEW:

Large Pacific Trough continues to slowly move inland over the
Great Basin. An upper level ridge ahead of it will keep
temperatures unseasonably warm for the next couple days. A weak
disturbance riding up the ridge today could produce a couple
isolated thunderstorms, with little rain expected and some gusty
winds possible near the storms.

As the trough moves toward the region on Tuesday, moisture drawn
in combined with the heating will generate some substantial CAPE
for mid September with values in the NBM 25-75% range reaching
1300 to 2700 J/kg. Mixing with 25 to 40kt shear with an advancing
cold front as the lifting mechanism this could lead to some severe
storms with Storm Prediction Center already highlighting the area
under a "Slight" risk 48 hours out.

With a stacked upper level and surface Low over central Montana, a
steady rain will follow the thunderstorms over central Montana,
but a dry slot behind the cold front could keep rainfall amounts
lower east of a line from Glasgow to Jordan. Storm totals west of
that line show probabilities of 50% or higher of QPF exceeding 1".
Meanwhile far eastern zones show only a 25% chance of exceeding
a half inch with central zones closer to a 50-60% chance of
exceedance.

Much cooler temperatures closer to seasonal average settle across
the region behind the front starting on Wednesday. The upper level
Low departs to the northeast on Thursday taking the rain with it,
with temperatures remaining cooler but close to what they should
be this time of year to finish out the week.

FORECAST CONFIDENCE & DEVIATIONS:

High confidence exists on warm and dry weather today and Tuesday
as well as the upcoming cooldown starting Wednesday.

Medium confidence on severe weather Tuesday, rainfall amounts in
western zones.

Medium to low confidence on how far west or east the dry slot ends
up setting up on Wednesday as well as rainfall amounts in eastern
zones.

Low confidence exists on thunderstorms today.

-Bernhart


&&

.AVIATION...
Last Updated: 0230Z

Category: VFR

Discussion: Dry weather expected this morning, a few isolated
thunderstorms may develop near KGGW and KOLF this afternoon.

Winds: E-SE 10-15kts

-Bernhart


&&

.GGW WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

weather.gov/glasgow