504
FXUS65 KTFX 141429
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
829 AM MDT Tue May 14 2024

.UPDATE...

Satellite imagery shows a shortwave disturbance tracking east-
southeast into north-central and southwest MT this morning.
Beneath this disturbance is a weak cold front with showers
concentrated near the front moving east across the area this
morning. By this afternoon, the front will slow/stall across SW MT
for a higher coverage of showers and a few thunderstorms there,
though some showers will linger into the afternoon further north
as well thanks to additional cooling aloft and afternoon
instability with lingering moisture. No significant changes from
precious forecast. Hoenisch

&&

.SYNOPSIS...

Widespread light, rain showers are expected through this evening
across the Northern Rockie, along with cooler temperatures. A
return to above normal temperatures is then expected from
Wednesday through Friday, with daily chance of showers and
thunderstorms. Unsettled weather conditions persist through the
weekend, with temperatures falling below normal.

&&

.AVIATION...
14/12Z TAF Period

Scattered SHRA and a few TSRA will continue to linger across North
Central and Southwestern Montana through the day today as a cold
front pushes through the area. Expect mainly VFR conditions to
prevail, with periods of MVFR to IFR conditions in and near TS/SHRA,
along with gusty winds and small hail aloft. SH/TSRA activity will
diminish from north to south this afternoon and evening, with just a
few lingering showers across SW MT after sunset. Ludwig

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

&&

.HYDROLOGY...

A small stream Flood Advisory remains in effect for Belt Creek in
southeastern portions of Cascade County, generally from just north
of Neihart to Sluice Boxes State Park. The Monarch Fire
Department reported that fallen trees in the creek from the recent
snowstorm are causing log jams in the creek. This is resulting in
the creek coming out of its banks in locations that normally do
not flood. The flood advisory will remain in effect until the
water returns back to the creek or the impact has been reduced.
- Brusda/Moldan

&&

.PREV DISCUSSION...
/ISSUED 550 AM MDT Tue May 14 2024/

Today through tonight...An upper level disturbance moving over the
Northern Rockies will bring predominately light rainfall to most of
Southwest through North Central Montana, with the "heaviest"
precipitation falling northeast of a Bozeman, to Helena, to Lincoln
line and southwest of a Lewistown, to Great Falls, to Choteau line
where there exists a 20-50% chance for rainfall amounts to exceed
0.25". High temperatures will be below normal today in wake of
yesterday`s Pacific front and a weak re-enforcing cold front this
morning, with readings rising into the low to mid-60s. Initial
stratiform rain early this morning will become more convective in
nature by the mid- to late morning hours, with showers and
thunderstorms gradually exiting Southwest through North Central
Montana from the evening through early morning hours on Wednesday.

Wednesday through Thursday...quasi northwest to zonal flow will
preside over the Northern Rockies through the period, which will
help to support the chances for daily showers and thunderstorms,
gusty winds, and above normal temperatures. While high winds are not
expected either day; most areas on Thursday have between a 30-70%
chance of exceeding 34kts, with a 50-60% chance of exceeding 41kts
in the wind prone areas along the Rocky Mountain Front.
Additionally, collapsing showers and thunderstorms Thursday
afternoon across Southwest through North Central Montana will be
capable of producing erratic, and potentially higher, wind gusts
given invert-V soundings. High temperatures on both days will run
from the upper 60s to upper 70s, which is 10 to nearly 20 degrees
above normal.

Friday through next Tuesday...the most "impactful" portion of the
period is expected from Friday through Saturday, with most clusters
supporting a scenario in which a shortwave trough digs southeast
from over British Columbia (Friday morning) to the Northern Rockies
(Saturday morning) and eventually over the High Plains (Saturday
evening). This shortwave looks to bring predominately light
precipitation over this 48hr period (Friday morning through Saturday
night) to the Northern Rockies, with areas north of the US Hwy 12
corridor generally having between a 10-25% chance of exceeding 0.5"
or precipitation (liquid equivalent). Falling snow levels to as low
as 5500ft (North Central Montana) to 7000ft (Southwest Montana) with
this disturbance will also allow for rain to change over to a wet,
heavy snow in the mountains, with most mountain locations having
between a 10-20% chance of seeing 2" or more of snow over this same
timeframe. Strong warm air advection and downsloping winds ahead of
the disturbance on Friday will once again push temperatures above
normal across most locations, with NBM probabilistic data supporting
a 30% or great chance for wind gusts in excess of 41kts southwest of
a Judith Gap, to Great Falls, to Cut Bank line (this also includes
the valleys of Southwest and Central Montana). Temperatures will
then fall below normal from Saturday through the remainder of the
period. Ensemble clusters begin to diverge on the
passage/timing/amplitude of disturbances through the remainder of
the weekend and upcoming work week; however, and overall unsettled
pattern can be expected. - Moldan

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  61  44  72  47 /  90  30  20  30
CTB  61  41  71  47 /  80  10  20  30
HLN  67  47  75  51 /  80  40  10  10
BZN  65  42  70  43 /  80  50  10  10
WYS  56  34  63  33 / 100  60  10  10
DLN  63  42  70  43 /  70  40  10   0
HVR  65  44  73  49 /  60  30  40  50
LWT  58  40  66  46 /  80  40  40  40

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
humidity
$$

http://www.weather.gov/greatfalls