599
FXUS65 KGGW 040903
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
303 AM MDT Sat May 4 2024

.DISCUSSION...
KEY MESSAGES:

- Night-time temperatures will drop below freezing in many areas
  tonight.

- Unusually warm conditions are expected on Sunday, but the
  southeast winds will be quite strong, with gusts into the 40s in
  many places.

- Another round of rain is expected starting Sunday night through
  at least Thursday. Ranges are looking on track to be around a
  inch and a half to 2 inches for many locations with moderate
  confidence(50-70%).

WEATHER PATTERN OVERVIEW:
Storm system that brought the brisk cool conditions today will
pull into eastern Canada from western Ontario and allow winds to
go light and variable while skies will clear. This will allow
temperatures to fall into the 20s for most places.

Sunshine will return Saturday and will be a pleasant day with
light winds. However, winds will increase from the southeast as
strong low pressure moves in from the Pacific NW. Look for
increasing and thickening clouds Saturday Night with rain showers
moving in Sunday Night.

A steadier rain will move into parts of the area Monday but a dry
slot may limit heavy rain potential next week. Models are still
not specific on timing and amounts yet.

(from previous discussion)
There is a small chance (5-20%) that some of these thunderstorms
could become severe, but with overnight convection being the main
periods of interest there will be no insolation and severe weather
will likely not occur. Will need to monitor SKEW- Ts in these
periods as they get within CAM model ranges for further scrutiny.

Tuesday through Thursday night: Closed low will migrate
northeastward and start to cut off from the warm air. However,
this just means that most of the convective elements will become
mainly stratiform. Main problem here onward is that positioning of
the low is in question with a range for its center position from
South Dakota all the way up to southern Saskatchewan. The low
looks to generate a trowal in most models which will bring a heavy
amount of rain to areas directly under or behind it. The majority
of the ensembles place this over eastern Montana which could
easily generate 1 to 2 inches to the area it hits. This feature
has remained consistent over the last 48 hours raising confidence
to moderate(50-70%).

Friday onward: A new ridge looks to move into the area which will
raise temps and dry conditions out. TFJ

&&

.AVIATION...

LAST UPDATED: 0830Z

FLIGHT CAT RANGE: VFR

DISCUSSION: Clouds will diminish this morning with a deck hanging
on just northeast of KOLF-KSDY. This afternoon will feature
mainly clear skies with increasing high to mid clouds tonight.

LLWS: Some low level wind shear will be possible (10-30% chance)
across northeast Montana from 07-12Z, but it currently does not
look to affect any of the four main terminals directly.

WIND: Light and variable through the morning. Becoming southerly
at 5 to 10 kts this afternoon. Then veering SE to E and increasing
to 5 to 15 kts this evening through tonight.

GAH



&&

.GGW WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory from midnight tonight to noon MDT Monday for
Central and Southeast Phillips-Central and Southern Valley-
Garfield-McCone-Petroleum.

&&

$$

weather.gov/glasgow