693
FXUS65 KGGW 190854
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
254 AM MDT Sun May 19 2024

.DISCUSSION...

KEY MESSAGES:

- An oncoming surface cold front will move in this morning,
  bringing rain showers and thunderstorm probabilities that will
  last through the early evening.

- Unsettled pattern continues with daily rain and thunderstorm
  chances especially in afternoon and evenings for the upcoming
  week.


WEATHER PATTERN OVERVIEW:

The cold front arriving today will keep things cool through the
early week with below normal temps. A series of weak troughs and
disturbances will move their way along the International Border
from west to east into the end of the forecast cycle. This will
act to bring in various shots of rain showers with isolated
thunderstorms embedded within, especially during the afternoon and
evening hours. Main time of focus for rain showers looks to be
the Wednesday to Friday periods with total QPF tallied up during
those times between a quarter inch to an inch. There is some
disagreement in mesoscale features with the passage of these
disturbances leading to moderate (50-70%) confidence. These
patterns look like they will hold into the weekend too, though
totals for that time are not yet known.


DEVIATIONS FROM NBM BASE FORECAST:

Hourly NBM PPI01 output for PoPs based on showers is not matching
up with radar echos early this morning and hourly PoPs had to be
increased to near 15-40% from near 0% baseline NBM for many
locations out through 9AM. Ended up using NamNest and ConsSHort
NPoPs and hand modifying to get closer to echos in time and space.
There may be a weak drop off after 9AM but the whole CWA should
expand back into widespread showers and isolated thunderstorms by
2PM.

GAH


&&

.AVIATION...

LAST UPDATED: 0830Z

FLIGHT CONDITIONS: VFR - MVFR

DISCUSSION: High clouds will increase this morning as another
disturbance moves into the area. This will bring in a low to
moderate (20 to 50 percent) probability of rain showers and
perhaps an isolated thunderstorms today. Low MVFR ceilings are
possible late in the afternoon and into evening with passing rain
showers. Showers activity should end after 06Z tonight.

WINDS: Light and variable this morning. Becoming mainly north at
5 to 15 kts this afternoon. Then backing to the northwest this
evening and claming to less than 10 kts after midnight.

GAH


&&

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


&&

$$

weather.gov/glasgow