High Wind Watch 13, NWS Great Falls, MT

Area Forecast Discussion
National Weather Service Great Falls MT
1157 PM MDT Sat Apr 8 2023

...Aviation Section Update...

.SYNOPSIS...

A quiet weather day continues through the afternoon and evening
today. Gusty winds across North-Central Montana through the rest of
this weekend. Near to above normal temperatures for Sunday through
Tuesday, with a cooler and unsettled weather pattern for midweek
into next weekend.

&&

.Update...

Evening update has been published, with primary change being to
raise overnight temperatures in downsloping areas over the plains
of Central and North Central Montana where breezy south to west
winds will help to keep the boundary layer decoupled and well
mixed. This well mixed boundary layer will lead to overnight
temperatures remaining above to well above freezing tonight, which
will allow for the continued melting of snow where a snowpack
remains. In addition to the adjustments made in temperatures, we
have issued several flood products this evening to account for
latest observations and expected impacts over the next several
mild days and nights. The Flood Watch was expanded to include the
Gallatin Valley from Sunday afternoon through Wednesday afternoon
as forecasted snowpack temperatures are expected to rise above
freezing across the valley by tomorrow afternoon, which is
expected to result in rapid snowmelt and the potential for
flooding. A Flood Advisory was also issued for portions of
Blaine, Hill, and Chouteau Counties to account for minor flooding
of low-lying areas and along creeks and streams, with local law
enforcement and Montana Department of Transportation noting
several roads having water over them. Finally, a Flood Warning
was issued for Clear Creek in west central Blaine County as stream
gages indicated that the creek was rapidly approaching Major
Flood stage. Flooding on Clear Creek was verified from spotter and
law enforcement reports, with portions of US Hwy 2 being impacted
by the flood waters.

&&

.AVIATION...
1157 PM MDT Sat Apr 8 2023 (09/06Z TAF Period)

Note: The National Weather Service Weather Forecast Office Manages
the following TAFs: KCTB, KHVR, KGTF, KLWT, KHLN, KBZN and KEKS

VFR conditions prevail for the duration of this forecast period at
all airfields. Wind/wind gusts pose the greatest impacts to aviation
operations. Southwesterly winds are forecast for our north central
and central Montana airfields, while generally southerly winds are
forecast for the southwest. Periods of gusty winds are forecast with
the strongest wind gusts included in the KCTB TAF, where winds are
forecast to gust to 34KT. As is typical with southerly winds across
the southwest portion of the state, wind gusts to 28KT are forecast
at KEKS. Wind speeds, of course, increase through mountain
valleys/passes.
- Fogleman

Refer to weather.gov/zlc for more detailed regional aviation weather
and hazard information.

&&

.HYDROLOGY...

Significant warming of temperatures through early next week will
result in the melting of the snowpack, which may increase the risk
of flooding for low lying and poor drainage areas, and along
creeks and stream emanating from the mountains. Although
temperatures are trending warmer this weekend into next week,
subsurface soil temperatures will still be below freezing, which
could exacerbate flooding in low lying areas where the soil is
saturated and or frozen. -AM/Moldan

&&

.PREV DISCUSSION...
/ISSUED 435 PM MDT Sat Apr 8 2023/

Upper level troughing weakened today and upper level ridging
continues to build in across the CWA this afternoon bringing
quiet weather conditions at the surface. Gusty winds along the
Rocky Mountain Front and adjacent Plains region continues this
afternoon, diminishing slightly overnight before picking back up
tomorrow afternoon and evening. A High Wind Watch for the
Northern Rocky Mountain Front has been issued for tomorrow
evening into late Sunday night as latest NBM 4.1 Probabilistic
Data suggests wind gusts over 75 mph have a moderate (between 50
and 75 percent) chance of developing during this time. Surface
high pressure brings mostly clear skies this weekend and near to
above normal temperatures beginning Sunday through Tuesday. Latest
NBM 4.1 Probabilistic Data shows afternoon high temperatures for
Monday range between the high 60s and mid 70s. With these warming
temperatures over the weekend into Monday and overnight low
temperatures are expected to be above freezing, snowmelt will
occur and hydrologic outlooks continue across the CWA with a
Flood Watch for Hill and Blaine County that also includes the Bear
Paw Mountains.

Tuesday is going to be an active weather day across our CWA as an
upper level trough is expected to develop off the Pacific Coast
and move into our region. A strong surface cold front has high
potential to develop. Ahead of this front will be strong gusty
winds, between 45 and 65 mph, mainly for north-south orientated
valleys across Southwest Montana and along the Rocky Mountain
Front. As the front moves through, temperatures have moderate
chances of falling 15 to 30 degrees from the low 60s to 30s.
Precipitation will begin as all rain along the Rocky Mountain
Front and move east across our CWA Tuesday. Then change over to a
mix of rain and snow for valleys and all snow for mountainous
terrain. Snow will continue in the mountains until Wednesday and
chances of precipitation for Wednesday through Friday are
currently moderate (between 50 and 75 percent). After Friday, we
should see another quiet weather pattern begin and a return to
near normal temperatures for next weekend. Webb

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  39  63  46  76 /   0   0   0   0
CTB  41  56  41  66 /   0   0   0   0
HLN  33  64  41  72 /   0   0   0   0
BZN  26  57  32  67 /  10   0   0   0
WYS  16  49  21  59 /  20   0   0   0
DLN  30  54  34  60 /   0   0   0   0
HVR  33  56  41  63 /   0   0   0   0
LWT  34  61  44  70 /   0   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

Flood Warning for Clear Creek until further notice.

Flood Advisory until 6 PM MDT Sunday for portions of Blaine, Hill,
and Chouteau Counties.

Flood Watch through Wednesday morning for Bears Paw Mountains
and Southern Blaine-Eastern Toole and Liberty-Hill County-
Northern Blaine County-Western and Central Chouteau County.

High Wind Watch from Sunday evening through late Sunday night
for East Glacier Park Region.

Flood Watch from Sunday afternoon through Wednesday morning for
Gallatin Valley.

&&

http://www.weather.gov/greatfalls

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
847 PM MDT SAT APR 8 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0818 PM     FLOOD            26 N GILDFORD           48.94N 110.22W
04/08/2023                   HILL               MT   DEPT OF HIGHWAYS

            MONTANA DEPARTMENT OF TRANSPORTATION REPORTS
            WATER COVERING THE ROADWAY ON HIGHWAY 232
            NEAR THE INTERNATIONAL BORDER.

&&

AM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
856 PM MDT SAT APR 8 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0547 PM     FLOOD            9 SW CHINOOK            48.50N 109.36W
04/08/2023                   BLAINE             MT   TRAINED SPOTTER

            SPOTTER INVESTIGATED ALONG CLEAR CREEK ROAD
            AND FOUND FLOODING ALONG CLEAR CREEK.
            SPOTTER ALSO NOTED THAT HIS 3 ACRE FEET
            RESERVOIR FILLED IN 5 HOURS.

&&

AM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
858 PM MDT SAT APR 8 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0600 PM     FLOOD            8 W CHINOOK             48.59N 109.40W
04/08/2023                   BLAINE             MT   LAW ENFORCEMENT

            LAW ENFORCEMENT REPORTED WATER OVER US
            HIGHWAY 2.

&&

AM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
1042 PM MDT SAT APR 8 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0856 PM     FLOOD            2 NNE HARLEM            48.56N 108.77W
04/08/2023                   BLAINE             MT   DEPT OF HIGHWAYS

            MONTANA DEPARTMENT OF TRANSPORTATION 511
            SITE REPORTS S-241 AT MP 1.8, SURFACE WATER
            HAZARD IN ALL LANES.

&&

JAF