Flood in Montana, May 6, 2023

Area Forecast Discussion
National Weather Service Great Falls MT
335 AM MDT Sat May 6 2023

.SYNOPSIS...

Cool and wet weather will continue across the area over the next
few days as a train of weather systems moves into the Northwestern
United States. Expect highs to be in the 50s and 60s through most
of next week with near daily chances for rain and thunderstorms.

&&

.DISCUSSION...

Rain continues this morning across portions of North Central
Montana as a band of moderate rainfall continues to stubbornly
persist over the area. While this band has not really moved much
through the overnight hours, there is finally some hint at a
northward push in the band from Chouteau County east. Given the
resistance to northward movement this band has had all night, I
opted to side more with some of the more recent
mesoscale/short term models with the placement of the heavier
rainfall, which shifted the bulls-eye of heavy precipitation a bit
southward. This band will eventually shift northward a bit through
the day today, but daytime heating will cause some destabilization
today, resulting in yet another round of showers and thunderstorms
across the area. While these showers and storms will generally not
put down quite as much rainfall as what fell in the ongoing band,
a few of the storms could produce briefly heavy rainfall.

Unsettled weather will linger on Sunday as southwesterly flow
aloft, along with upper level disturbances, continue to produce
rainfall across the area. While Sunday's round will generally
focus on Southwestern Montana, a few showers and thunderstorms
will find their way into North Central MT. Like with Saturday,
some of the storms will produce some locally heavy rainfall, and
those that do may cause some ponding of water on roads or low
lying areas.

Not much will change as we start the work week, as Southwesterly
flow aloft, along with additional upper level disturbances,
continue to produce scattered to widespread rain shower and
thunderstorm activity across the area. The strongest of these
systems will push through on Wednesday, bringing another round of
widespread moderate to heavy rainfall with it. Beyond Wednesday,
current weather models attempt to get this last system, an upper
level low, out of the area rather quickly, but history tells us
that upper level lows don't exactly like to move quickly as we
head into the summer months, so there is less confidence in the
forecast as we head into later next week. Ludwig

&&

.AVIATION...
1155 PM MDT Fri May 5 2023 (06/06Z TAF Period)

Areas of showers (with an isolated embedded thunderstorm) will
continue to push through portions of North Central Montana tonight,
mainly for KGTF, though KLWT and KHLN will see some occasional
rainfall through sunrise. As we progress through the day on
Saturday, expect another round of widespread showers and isolated
thunderstorms across the area. Ludwig

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

&&

.HYDROLOGY...

Numerous rivers, creeks, and streams across Southwestern and
North Central Montana are near or at bankfull. Localized flooding
due to snow melt combined with heavy rain is now being being
reported at Belt Creek near Monarch. A Flood Advisory has been
issued for this area. While widespread impacts from flooding are
generally not expected for other areas, those with interests along
local waterways, especially in Lewis and Clark and Cascade
Counties, should be prepared to act should water levels rise
further than currently anticipated.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  56  40  61  42 /  60  40  50  30
CTB  53  40  58  37 /  90  70  50  20
HLN  60  41  63  42 /  80  50  60  40
BZN  60  36  58  36 /  60  70  70  40
WYS  48  25  48  25 /  60  40  80  50
DLN  57  35  55  36 /  70  70  70  40
HVR  58  43  62  42 / 100  60  60  40
LWT  58  38  58  39 /  80  70  70  50

&&

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

http://www.weather.gov/greatfalls