126
FXUS65 KTFX 120543
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1145 PM MDT Sat May 11 2024

Updated aviation sections

.SYNOPSIS...
The ongoing warm weekend will continue into Monday. Showers and a
few thunderstorms will develop along the Hi-Line tonight, with
additional afternoon and evening showers and thunderstorms likely
across the plains Sunday and Monday. A cooler and more unsettled
pattern will arrive for mid-week.

&&

.UPDATE...
Current forecast is on track. No forecast updates planned for
this evening. An upper level ridge is building over the Pacific
Northwest, resulting in a northwesterly flow aloft over Central
Montana. A weak upper level disturbance is sliding southeastward
in this flow aloft. A few showers/isolated thunderstorms could
slide into the Havre/Harlem areas, mostly after Midnight.
Instability is low, so the chances for any lightning are also low.
Additionally, this disturbance is not very strong, so most
locations will receive less than 0.10 inches of precipitation if
it does rain. Overnight low temperatures look on track.

Note, there will be some increased cloud cover over North Central
MT overnight as this upper level disturbance moves through. Even
though I am not expecting overcast skies, the cloud cover could
limit viewing of the Aurora at times tonight. (It will not be as
clear as last night for most areas.) Brusda

&&

.AVIATION...
12/06Z TAF Period

Mainly VFR conditions are expected over the next 24 hours with just
some MVFR conditions in and around KHVR tonight as a few rain
showers move through. Aside from these rain showers, expect clouds
to linger across the area with some wind gusts along the Rocky
Mountain Front. Ludwig

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

&&

.HYDROLOGY...
Clear Creek continues to slowly fall. The creek is expected to
fall below flood stage overnight tonight. Thus the flood warning
for this creek will likely be cancelled later tonight.

The flood watch continues for the Bears Paw Mountains. However,
no new flood impacts were reported today. If that trend continues
overnight, the flood watch could be cancelled early.

The flood watch continues for the mountain ranges of Central
Montana. No new flood impacts were reported today. This is good
news, as this means the runoff is coming off slowly or the runoff
is soaking into the ground. In either case, if this trend
continues, this flood watch could also be cancelled early. Brusda

&&

.PREV DISCUSSION...
/ISSUED 300 PM MDT Sat May 11 2024/

Through Monday... Upper level ridging, with axis over the west
coast, is slowly building eastward. With ridge axis off to the west,
flow aloft is out of the northwest. A weak wave diving southeastward
through this flow will result in showers and a couple thunderstorms
tonight, mainly across eastern portions of the Hi-Line.  This
activity moves east of the area by 7AM Sunday.

Additional instability will develop across Central and North-central
Montana Sunday, resulting in a round of isolated afternoon and
evening showers and thunderstorms. Concerns with thunderstorms that
form will be for gusty winds, given relatively deep mixing and
inverted-V soundings.

Expect more of the same on Monday, though the opportunity for
showers and perhaps a thunderstorm or two will spread further
southwest into Southwest Montana. Additionally, breezy westerly
winds look to develop over the plains as a passing wave moves
overhead. -AM

Tuesday through next Saturday... Expect periods of rainfall to
continue through the day on Tuesday as moisture continues to work
into the area from the north and west. For the most part,
precipitation will be rainfall except at the highest elevations even
as cooler air from Canada pours into the region behind a surface
cold front that will work in with the rain.

Beyond Tuesday, a ridge will develop to our southwest, but with a
northwesterly flow aloft in place, expect near to perhaps a bit
cooler than average temperatures, with opportunities for showers.
Ludwig/AM

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  48  78  49  76 /  20  20  10  20
CTB  47  78  49  73 /  20  20   0  20
HLN  50  80  51  77 /   0  10   0  20
BZN  43  76  46  73 /   0   0  10  50
WYS  35  69  37  65 /  10  10  10  60
DLN  42  76  46  73 /   0   0  10  30
HVR  48  76  49  80 /  50  10  30  30
LWT  45  70  46  71 /  20  30  20  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Flood highlights are in effect for portions of the CWA.

&&

$$

http://www.weather.gov/greatfalls