318
FXUS65 KGGW 211010
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
410 AM MDT Fri Jun 21 2024

.DISCUSSION...

KEY MESSAGES:
- Shower and thunderstorm chances increase today, with stronger
  storms and more widespread wetting rain expected.

- A few isolated severe cells late this afternoon and evening are
  possible, with large hail the primary threats.

- Warmer and drier weather expected for next week.

WEATHER PATTERN OVERVIEW:

An active jet/zonal flow will remain across the northern
States/Canadian border region for the next week. A shortwave
pushing through the northern Rockies today will help trigger
thunderstorm development this afternoon. With southeast low level
flow will aid in developing favorable conditions for supercells
with deep-layer shear, strong buoyancy, and relatively low cloud
bases. High pressure over the northern plains will keep an
instability axis over central Montana with storms propagating
southeast through the early evening. This will put the best threat
for severe weather over the southwest zones (southern Phillips,
western Garfield and Petroleum counties) for the late afternoon
and evening.

As the shortwave moves east, the storms will also lift east, but
conditions will be not quite as favorable for severe storms. Rain
totals through Saturday morning vary from a tenth to a half inch
over the CWA, with locally higher amounts where storms train.
Afterward, a ridging pattern will favor seasonably warm and drier
conditions from Sunday into the middle of next week.

FORECAST CONFIDENCE and DEVIATIONS:
There is high confidence (60-80%) in general thunder with minimal
chances (10%) for severe weather at a particular point Friday
afternoon and evening. Confidence is medium to high for the
general conditions remaining slightly warmer and drier than normal
through much of next week.



&&

.AVIATION...
VFR - MVFR.

Low clouds will linger over the Yellowstone Valley, with MVFR
conditions at KGDV, possibly spreading to the other TAF sites
through the morning hours. Ceilings will lift as thunderstorms
develop over the region this afternoon and evening, although brief
MVFR conditions are possible with some of the stronger storms.


&&

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

$$

weather.gov/glasgow