Winter Storm in Montana, April 1, 2020

Area Forecast Discussion
National Weather Service Great Falls MT
545 AM MDT Wed Apr 1 2020

...Update to Aviation...

.SYNOPSIS...
Periods of snow will continue early this morning before tapering
off to scattered showers for the remainder of the day. Much
colder temperatures will prevail today and Thursday before a
gradual warm up begins on Friday. Scattered showers will continue
to affect the region through the end of the week, especially in
the mountains.

&&

.DISCUSSION...

Satellite and radar are indicating that the bulk of moisture
associated with this weather system has moved through the forecast
area. However, there is still enough moisture upstream to continue
likely to categorical PoPs for much of the CWA through noon.
Exception is the northwest plains zones, including Glacier, Toole,
Liberty, and eastern portions of Pondera and Teton Counties where
only isolated/scattered light snow can be expected this morning.
In this region I have already cancelled the Winter Weather
Advisory since very few observations are indicating any snowfall.
I have kept the remainder of the winter highlights active through
noon. Still, I would not be too surprised to see snow taper off
fast enough for the mid-morning update forecaster to end the
remainder of the highlights a bit early. Temperatures will be well
below seasonal averages for early April with overnight lows
tonight likely to fall to near or below zero in many areas. High
temperatures today and Thursday will be in the teens and 20s
north, and near 30 in the Southwest as cold high pressure sits
over the region. Luckily, we are far enough into the spring (?)
season that the cold air will not become entrenched so highs on
Friday should warm back up into the 30s. Only isolated/scattered
snow showers are expected through the remainder of the week. mpj

Friday night through next Wednesday...active pattern will persist
across much of the Western CONUS/Canada over the period, with large
scale troughing generally dominating the pattern. A few periods of
transient ridging (i.e. Saturday night through Sunday night and then
again on Wednesday) are expected, which will generally limit
precipitation to the mountains of Southwest/Central Montana and
along the Continental Divide. High temperatures will gradually
moderate to near climatological norms by Monday, but given the
overall pattern I woudln't be surprised if high temperatures remain
slightly below normal from Monday through Wednesday. A few notable
disturbance embedded within the overall large scale troughing
pattern are expected to impact the region Friday night through
Saturday (most impacts felt along the Northern Rocky Mountain Front),
and Monday morning through Tuesday (most impacts felt along the
Continental Divide and across Southwest Montana, especially south of
the I-15 corridor). - Moldan

&&

.Aviation...
Updated 545 AM MDT Wed Apr 1 2020 (01/12Z TAF Period)

Areas of light snow will continue to affect many terminals through
mid to late morning as the weather system gradually moves away from
the forecast area. IFR/MVFR conditions in low clouds and snow will
give way to MVFR/low VFR conditions as snow diminishes and ceilings
slowly lift. Most of the forecast area should anticipate low level
clouds persisting into Thursday morning. Exception is in far
Southwest Montana where clouds remain mid-level and some areas have
already become mostly clear for prevailing VFR condition. Most
mountains will remain obscured through the period. mpj

&&

.HYDROLOGY...

As of Tuesday evening, snow melt out of Canada has caused some
smaller creeks in Hill and Blaine County to approach and exceed
Action Stage. The only creek forecast to exceed flood stage is
Battle Creek near the town of Chinook, and it is only by 0.3 feet.
Am therefore not expecting significant impacts from any flooding
there, but it it is worth an Areal Flood Advisory. Two other creeks -
 Clear Creek near Chinook, Lodge Creek along the International
Boundary - are running high, but are not forecast to go over flood
stage. However, poor drainage areas may cause minor low land
flooding there. Have therefore included these two areas in the
Advisory. Battle Creek is forecast to go below flood stage Wednesday
evening.  Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  20   3  23   7 /  50  10  10  10
CTB  16   3  21   6 /  40  10  10  10
HLN  27   9  31  13 /  40  20  10  10
BZN  30  11  29  10 /  50  40  20   0
WYS  30   4  27   0 /  50  50  50  10
DLN  31  10  30  12 /  40  40  10   0
HVR  19   2  21   4 /  60  10   0  10
LWT  16  -2  19   1 /  80  30  20  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon MDT today Beaverhead...
Broadwater...Gallatin...Jefferson...Madison.

Winter Weather Advisory until noon MDT today Cascade...Meagher.

Winter Storm Warning until noon MDT today Blaine...Chouteau...
Fergus...Hill...Judith Basin.

Winter Weather Advisory until noon MDT today Central and
Southern Lewis and Clark...Northern Rocky Mountain Front...
Southern Rocky Mountain Front.

&&

http://www.weather.gov/greatfalls