148
FXUS65 KGGW 132010
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
210 PM MDT Mon May 13 2024

.DISCUSSION...

KEY MESSAGES:

- There will be frequent chances for showers and thunderstorms
  beginning this afternoon (including the risk for gusty winds
  from outflows of storms late this afternoon/evening) and
  continuing for the next several days.

- Warmer than normal temperatures linger, before a cold frontal
  passage later today leads to more seasonal conditions this week.

WEATHER PATTERN OVERVIEW:

+++ AFTERNOON UPDATE: Storms have begun breaking this morning`s
cap across the higher terrain near the Little Rockies/Bear Paws in
Montana and near the Cypress Hills along the Alberta/Saskatchewan
border. This convection has developed up to 2 hours earlier than
the 12Z NAM Nest guidance. Timing of outflow boundaries still
generally remains the same as discussed below. +++

Wildfire smoke has dispersed more across the region overnight,
with some haze and moderate air quality remaining. A cold front
will move through the forecast area this afternoon and night.
Models and ensembles are pointing toward just enough instability
and shear ingredients suggestive for a few strong thunderstorms
with this system. Some (20-40%) of the 00Z HREF members show gusty
winds in excess of 40 mph being produced by the convective storms
through about midnight/early Tuesday morning. However, except for
near the Canadian border there is less than a 30% chance of a
tenth of an inch of rainfall through tonight due to the more
localized nature of convection. The pattern favors near normal
temperatures Tuesday and beyond, though ensemble models differ on
the extent of troughing and moisture available for continued
shower/thunderstorm chances.

CONFIDENCE AND POTENTIAL DEVIATIONS FROM BASE FORECAST:
High confidence exists on the general temperature trend this week.
Adjustments were made to the wind and wind gust grids through
early Tuesday morning to account for local, convective wind
enhancement. There is low confidence on the timing of showers and
thunderstorms Tuesday and beyond, as well as the total amount of
rain for any particular location.

-Zanker/Enriquez



&&

.AVIATION...

LAST UPDATED: 2000Z

FLIGHT CONDITIONS: VFR (MVFR/IFR in isolated thunderstorm)

DISCUSSION: Thinner smoke remains across the region, but
visibilites remain above 10 SM. Otherwise, towering cumulus
continue to build across north central Montana, moving into the
region late this afternoon/evening. Scattered thunderstorms will
reduce the flight category briefly, but recover afterward. After a
brief period of no precipitation Tuesday morning, another period
of afternoon showers and thunderstorms are expected across
northeast Montana.

WINDS: Briefly gusty and erratic wind potential exists with
showers/thunderstorms and their associated outflow boundaries.
Otherwise, winds remain light and variable tonight. Tuesday, winds
are more northwesterly through 15-20 kts.

-Enriquez


&&

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

$$

weather.gov/glasgow