059
FXUS65 KGGW 120925
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
325 AM MDT Sun May 12 2024

.DISCUSSION...

KEY MESSAGES:

- Canadian wildfire smoke is causing reductions in visibility and
  air quality this morning, likely to mostly mix out in the
  afternoon.

- Warmer than normal temperatures continue, particularly on
  Monday.

- There will be frequent chances for showers and thunderstorms
  beginning Monday afternoon and continuing for the next several
  days.

WEATHER PATTERN OVERVIEW:

A shortwave trough with a weak cold front is bringing slightly
cooler temperatures today along with a few rain showers and
wildfire smoke out of Canada. Temperatures rebound on Monday
ahead of a stronger shortwave trough, with a cold front that will
move through the forecast area Monday afternoon and night. Models
and ensembles are pointing towards enough instability for a few
thunderstorms with this system. The NBM generally has a 20-30
percent probability of a thunderstorm Monday afternoon and night
at this point and less than a 40 percent chance of a tenth of an
inch of rainfall 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:

The main deviation was to use HRRR smoke concentrations with
slight adjustment when comparing to current observations to add
in mention of smoke and visibility as low as 3 miles today. High
confidence exists on above average temperatures through Monday.
The current NBM highs continue to be at the lower end of the NBM
possibilities (5-25%), so raised highs about a few degrees so that
most locations are closer to the NBM 25% that matched up well
yesterday. 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

&&

.AVIATION...

LAST UPDATED: 0900Z

FLIGHT CONDITIONS: MVFR - VFR

DISCUSSION: Smoke is reducing visibility into the MVFR category
this morning, particularly for KGGW and KOLF. Based on forecast smoke
concentrations, there is medium confidence for gradual
improvement by the afternoon. Otherwise, look for isolated rain
showers this morning, scattered mid level clouds and winds around
10 knots or less.

&&

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

$$

weather.gov/glasgow