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000
FXUS65 KGGW 220839
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
239 AM MDT Mon Apr 22 2024

.DISCUSSION...

KEY MESSAGES:

1) Strong west to northwest winds in all areas with critical fire
weather south of US Highway 2 today.

2) Showers and isolated thunderstorms are expected north this
afternoon and evening.

3) Otherwise, a broad ridge pattern builds into the area this
week resulting in mostly dry and seasonable conditions.

WEATHER PATTERN OVERVIEW: Stacked upper/surface low will move
across southern Saskatchewan today bringing strong west to NW
winds over the forecast area. There will also be some rain showers
spinning around this low, some of which will move across the
northern zones of the forecast area this afternoon and evening.
The atmosphere is expected to be unstable enough this afternoon
and evening for isolated thunderstorms to mix in with those
showers. While NBM has forecast reaching wind gust around 50 mph
today in some areas, the probability of wind gusts exceeding 55
mph is less than 30 percent in most areas and as high as 50
percent in parts of Phillips and Valley Counties. At this point,
the probability of reaching High Wind Warning criteria is low
enough that we will hold off on issuing any High Wind Warning and
maintain a Lake Wind Advisory over Fort Peck Lake. The most likely
scenario for any spot getting a 60+ mph wind gust today would be
in a rain shower or thunderstorm. South of US highway 2, RH less
than 25 percent will create critical fire weather conditions today
and a Red Flag Warning remains in effect.

The low moves to the east tonight and high pressure moves in
diminishing the winds. Upper ridge moves in and by Wednesday,
temperatures will be warmer than normal. A shortwave trough brings
a cold front through the area on Thursday with slightly cooler
temperatures on Friday. An upper trough is expected over the
weekend but models and ensembles differ on the weather associated
with this system at this time.

CONFIDENCE AND POTENTIAL DEVIATIONS FROM BASE FORECAST:

Confidence is high for strong winds in all areas today. Confidence
for wind speeds to reach High Wind Warning Criteria (gusts 58+
mph) is low and too low to issue a Warning. Confidence for
critical fire weather conditions today is high south of the
Missouri River and over the Little Rocky Mountains and diminishes
significantly north of US Highway 2 where much higher RH is
expected. With SPC having the northern zone of the forecast in a
general thunderstorm outlook for today, add the possibility of
thunderstorms that the base forecast did not have.

High confidence in the mid week ridge and cold front on Thursday.
Low confidence of precipitation chances over the weekend.



&&

.AVIATION...

LAST UPDATED: 0820Z

FLIGHT CAT RANGE: VFR - MVFR

DISCUSSION: Stacked low will be over Saskatchewan today which will
bring strong west to NW winds over the area. Skies will start
mostly clear this morning. Mid level and low VFR clouds will move
in from the north during the day today. There will be isolated to
scattered rain showers with a thunderstorm possible this
afternoon and evening. MVFR clouds will begin to enter the area
this evening from the northeast and will start to impact KOLF and
KSDY around 03Z-06Z and could reach KGDV overnight.

LLWS: There is a (20%-30%) chance for Low Level Wind Shear this
morning across the terminals until winds aloft start mixing down
after sunrise.

SFC WIND: West at 10 to 20 kts early increasing to WNW 25 to 35
knots with gusts to 45 knots by late morning. NW winds will
diminish to 5 to 15 knots this evening.

&&

.FIRE WEATHER...
The latest forecast guidance suggests wetting rain probabilities
are low (under 20%) and mainly north of the Missouri River.
Northwest winds of 25 to 35 mph will be widespread across the
entire area today, along with gusts to 50 mph. Over the past two
weeks, Dawson, Prairie and Wibaux counties have received around 30
percent of normal precipitation. Based on this, there is high (90
percent) confidence locations south of a line from the Little
Rockies to Wibaux will have critical conditions for fire weather
today. This is in response to forecast winds reaching and/or
exceeding RH values this afternoon. A Red Flag Warning remains in
effect for Zones 122, 135, 136, and 137 on today from 10 AM to 9
PM. On Tuesday, low RH 20-30% is expected but winds will be light
and variable.


&&

.GGW WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory until 6 AM MDT Tuesday for Central and
Southeast Phillips-Central and Southern Valley-Garfield-McCone-
Petroleum.

Red Flag Warning from 10 AM this morning to 9 PM MDT this
evening for Dawson/McCone/Prairie/Richland/Wibaux Counties-
Southern Petroleum and Southern Garfield Counties-The Little
Rockies-The Lower Missouri River Breaks including the Charles M
Russell National Wildlife Refuge.

&&

$$

weather.gov/glasgow