High Wind in Montana, May 24, 2021

Area Forecast Discussion
National Weather Service Great Falls MT
828 AM MDT Mon May 24 2021

.UPDATE...
Minor adjustments made this morning to the location and amount of
precipitation currently tracking through the area today, as well
as morning temperatures and RH values. Otherwise the forecast
remains on track with another few days of precipitation tracking
through the area and a slightly warmer and drier end of the week.

&&

.SYNOPSIS...
Gusty winds will increase across the region today with locations
along the Rocky Mountain Front seeing gusts as high as 55 mph.
Areas of rain and snow in the morning will change over to
scattered showers this afternoon with isolated thunderstorms
possible over southwestern Montana. Warmer temperatures are
expected through the week, but another round of widespread
precipitation possible on Wednesday.

&&

.AVIATION...
550 AM MDT Mon May 24 2021 (24/12Z TAF period)

Upper level low along the Montana-Canadian border will move eastward
today with areas of rain and mountain snow diminishing through the
morning. Strong westerly flow aloft combines with a tightening
surface pressure gradient for strong and gusty west winds along the
Rocky Mountain Front and over the adjacent plains of central
Montana. The strong winds will persist into this evening with a few
locations possibly seeing borderline severe wind gusts. Areas of low
level wind shear can also be expected. VFR conditions prevail
through the forecast period with local IFR/MVFR conditions possible
in isolated/scattered showers and thunderstorms. mpj

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

&&

.HYDROLOGY...
Locally heavy showers and thunderstorms expected this afternoon
and evening could cause short lived minor flooding of low lying
areas and some urban areas. Warming temperatures through the week
will allow mountain snow to begin melting out, leading to rises on
area streams and rivers. Additionally, afternoon and evening
showers and thunderstorms can be expected most days, possibly
causing localized small stream and urban flooding. Another round
of more widespread precipitation is expected for Wednesday.

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.PREV DISCUSSION...
/ISSUED 550 AM MDT Mon May 24 2021/

Upper level closed low over Montana will continue moving to the
northeast today with downslope pressure gradients along the Rocky
Mountain Front and over the adjacent plains becoming increasingly
strong through the day. Have significantly increased forecast
winds for today through this evening and can not rule out the
chance that some locations could see gusts become borderline
severe. Otherwise, periods of rain and mountain snow will continue
to affect portions of central and north central Montana this
morning. Current winter weather advisories for these regions are
scheduled to expire at noon which appears to be appropriate at
this time. Short wave ridging builds over the state tonight and
Tuesday as the upper level low ejects to the east through southern
Canada and another system moves into the Pacific Northwest coast.
Warmer temperatures can be expected through mid-week with
isolated to scattered showers and thunderstorms possible during
the afternoon and evening hours Monday and Tuesday. The
aforementioned Pacific Northwest system moves slowly inland and
finally reaches central Montana on Wednesday. There is good model
agreement that another widespread rain and high mountain snow
event will develop late Tuesday night through Wednesday. With
warming temperatures and increasing snow levels, am anticipating
that snowfall will be limited to well above pass level. As such,
am not expecting the need for any winter weather highlights, but
will continue to monitor the situation.

Continued progressive flow aloft moves the Wednesday system
eastward with diminishing showers expected during the evening.
Mostly dry conditions are then expected late Wednesday night
through early Friday morning as another upper level ridge moves
overhead. The next upper level low will move eastward through
southern Canada Friday and Friday night for a return to somewhat
unsettled conditions. However, the low's position north of the
border will produce light to moderate downslope winds which
should limit precipitation at lower elevations to
isolated/scattered shower/thunderstorm activity while the
mountains see another round of wetting precipitation.

Diagnostic model solutions diverge for the weekend and early next
week, but ensembles and the National Blend of Models indicate
generally quiet west-northwest flow aloft through this period.
Isolated to possibly scattered afternoon and evening showers and
continued near-seasonal temperatures should be expected during
this period. mpj

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.PRELIMINARY POINT TEMPS/POPS...
GTF  57  43  60  42 /  60  40  50  50
CTB  53  41  55  39 /  80  60  50  40
HLN  60  43  65  44 /  30  20  40  80
BZN  61  36  65  41 /  30  20  50  90
WYS  51  28  57  33 /  70  30  80  90
DLN  56  34  60  39 /  10  10  60  80
HVR  59  46  60  41 /  70  60  40  20
LWT  59  42  60  40 /  40  30  40  60

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.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon MDT today above 5500 feet for
Northern Rocky Mountain Front...Southern Rocky Mountain Front.

Winter Weather Advisory until noon MDT today above 5500 feet for
Cascade...Judith Basin...Meagher.

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http://www.weather.gov/greatfalls