High Wind in Montana, April 4 to 6, 2022

Area Forecast Discussion
National Weather Service Glasgow MT
1243 PM MDT Mon Apr 4 2022

.DISCUSSION...

AFTERNOON UPDATE:
Continued the previous blend of NPoP CAM models for PoP on
through Tuesday night which appears to be delivering a much higher
level of detail for rain positioning around the developing low as
it swings through Tuesday Night, and then let NBM take over at
Wednesday morning.

Winds were the interesting conundrum. There is a nearly 20 kts
difference between the current NBM and the NBMEXP for Wind Gusts
through Tuesday. Ended up blending the two which seemed to reach
a consensus very similar to SPC's HREF CAMs output. Looking at
various models 850 mb winds brings a streak of between 50 to 70
kts through the area. There is also about a two county wide
range of positional placement of the jetstreak and the lapse
rates under almost all areas are high enough to drag it to the
surface very easily. Have elected to add on northern Phillips,
Valley, McCone, and Dawson county as they exist with the realm of
high standard deviation of gusts and could easily break high wind
if the jet moves over eastward from the best guessed placement at
850 mb.

When it comes to Fire Weather, have decided to go ahead with the
watch, CAMs model placement of PoPs is dead on target from this
mornings update, however virga is the main outcome under the
convection which means the surface will not see significant
moisture prior to the highs winds and this keeps the chance for
fire runs high for now with the dry fuels. Will let the evening
shift have one last look at it before pulling the trigger for Red
Flag. GAH

930AM UPDATE:
Sky coverage appears to be be running about 3 hours faster than
NBM currently has. However, CAM models have this covered and ended
up using the NPoP blend of available CAMs to fill out the hourly
PoPs through 6AM tomorrow morning. This brings rain showers across
the area about 3 hours earlier than predicted, but appears to be
matching correctly when looking at current developing radar echos
to the west. Will keep an eye on the Lewistown and Havre obs'
precip to confirm suspicions. Currently, CAPE does not look to get
above 100 J/kg and have held off on thunder language with shower
passage, though convective elements are finally getting close to a
slight chance for lightning at this point in the season.

Looking further ahead will keep and eye on the next tier of
counties/zone east of the High Wind Watch, as there is quite the
spread on exactly how far east high winds will extend. A nearly
county wide standard deviation of 8 to 10 kts exists along the far
eastern border in both the NBM and NBM EXP leading to this
uncertainty.

Will also be further evaluating the chance for a Fire Weather
Watch in the southwest as fuels are dry enough to combust and
cause runs when combined with the high wind. The question will be
how much rain falls in that area prior to the high winds kicking
in. Currently, it is modeled as very little in the QPF fields
which points to a higher probability this afternoon of issuance.
GAH

MORNING DISCUSSION:
Flat upper ridge over the region today with strong jet beginning
to push into the Pacific Northwest. This jet will push a warm
front across eastern Montana this afternoon while low pressure
develops over southern Alberta. Warm temperatures and low humidity
will lead to elevated fire concerns for today, with some gusty
winds and light showers expected in the afternoon.

The Pacific jet and low begin to dive south across Montana
tonight, with the stacked low clipping the northeast corner of the
state by Tuesday afternoon. Strong west to northwest winds will
develop to the southwest of the track of the low, and models have
been very consistent with this for a few days, so have updated the
High Wind Watch to a Warning.

Fire weather concerns will remain elevated into Tuesday given the
high wind potential and dry fuels across the region. Cooler
temperatures, rising humidity and the chance of precipitation by
Tuesday afternoon will be mitigating factors for fire dangers.
Cooler temperatures are expected midweek as the low pressure
system moves across the region. As the upper ridge builds
back late in the week, temperatures will warm. Next weekend or
early next week could see another chance for precipitation with
another low pressure system moving through the region.

&&

.AVIATION...
LAST UPDATED: 1830Z

FLIGHT CAT: VFR - MVFR

DISCUSSION: Clouds will increase from the west through the
day, and a few rain showers are possible this afternoon and
evening as a warm front lifts across the region. Rain showers are
expected again late Tuesday with MVFR ceilings possible just
ahead of the rain Tuesday morning around 12 to 18Z.

WIND: Southwest and increasing to 15 to 20 gust 25 kts this
afternoon. Veering to the west overnight. Increasing to 20 to 30
gust 40 kts late Tuesday morning and further veering to the
northwest Tuesday afternoon through the evening hours.

GAH

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 6 AM Tuesday to 4 AM MDT Wednesday for
Central and Southeast Phillips...Central and Southern Valley...
Dawson...Garfield...McCone...Northern Phillips...Petroleum...
Prairie.

Fire Weather Watch from Tuesday morning through Tuesday evening
for MTZ135>137.

High Wind Warning from 9 PM this evening to 4 AM MDT Wednesday
for Southwest Phillips.

Lake Wind Advisory until 6 AM MDT Tuesday For Fort Peck Lake for
Central and Southern Valley...Garfield.

&&

weather.gov/glasgow