744
FXUS65 KTFX 132058
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
258 PM MDT Mon May 13 2024

.SYNOPSIS...

Rain showers and thunderstorms rest of today into tonight. More
widespread rain showers tomorrow morning and afternoon and cooler
temperatures. Return to normal temperatures for Wednesday with daily
chances of showers. Unsettled weather conditions and cooler weekend
in store.

&&

.DISCUSSION...

Key Points for the Short Term:

- Rain showers and thunderstorms continue tonight into tomorrow
  as a cold front moves through tonight bringing cooler and wetter
  conditions.

- Breezy conditions and above normal temperatures today.

Rest of today through tomorrow night... As of 2 PM, latest radar
continues to show thunderstorms and rain showers developing along
the Hi-Line to Canadian Border, Rocky Mountain Front, and adjacent
Hi-Plains region. Satellite imagery continues to support showers and
thunderstorms across Southwest Montana, especially along the MT/ID
border. While some locations may not be seeing a shower or
thunderstorm, it`s important to be weather ready when heading
outdoors through tomorrow. Latest National Blend of Models 4.2
probabilistic data suggests that between now and 7 PM continues to
be the best likelihood (>20%) of general thunderstorm activity to
continue for along the Hi-Line and Canadian Border as well as
across the MT/ID Border and West Yellowstone area. Primary
concerns continue to be with any developed thunderstorms today are
lightning, a brief downpour, gusty winds, and small/pea sized
hail. After 7 PM, thunderstorm activity is supported to diminish
as we lose necessary ingredients to help initiate convection
(thunderstorms). There can still be a few light rain showers
across Southwest Montana this evening as latest high resolution
model guidance supports the probability of precipitation through
the early evening hours.

Cooler temperatures are in store tomorrow as the cold front moves
across our area, bringing scattered rain showers tomorrow morning
from northwest to southeast from North Central to Southwest
Montana. Rain on snow with already melting snowpack can cause
localized minor flooding in areas of poor drainage for tomorrow
for the Highwood and Little Belt Mountains. Rain showers diminish
for Tuesday evening across the area and high pressure is favored
to move back in for Tuesday night into Wednesday. Webb

Extended (Wednesday through next Monday)... Expect seasonable
weather through the second half of the work week as upper level
ridging over the eastern Pacific keeps our upper level flow westerly
to northwesterly with a few weak disturbances moving through the
area. For the most part, these disturbances will mostly just result
in some periods of gusty winds Thursday and Friday as a few rounds
of cooler air work their way into the area, but areas along and
north of US 2 could see a few periods of light rainfall Thursday and
Friday as these disturbances move through. Looking towards the
weekend, there seems to be some consensus that a slightly more
notable trough will work its way into the Northern Rockies, which
could help spur some more widespread rain and mountain snow to at
least parts of the area for the weekend. Ensembles diverge for the
start of the new work week, though the overall pattern appears to
remain unsettled as we head into next week. Ludwig

&&

.AVIATION...
13/18Z TAF Period

Concerns this TAF period include increasing westerly to
northwesterly winds this afternoon primarily across the plains,
widely scattered showers and thunderstorms this afternoon into the
overnight across most areas, and low VFR to MVFR ceilings across the
plains tomorrow morning associated with additional showers. Overall,
the scattered nature of showers and thunderstorms this afternoon as
well as limited confidence with respect to timing of any
thunderstorms at terminals has led to the exclusion of thunder
mentions in TAFs at this time. Trends will be monitored this
afternoon, with thunder mentions being introduced as confidence in
the situation grows. Any showers or thunderstorms will carry a gusty
outflow threat. -AM

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  47  61  43  71 /  50  90  30  10
CTB  46  61  41  70 /  60  70  10  10
HLN  51  66  46  74 /  20  80  30  10
BZN  43  64  42  69 /  60  70  40  10
WYS  36  58  34  62 /  70  70  30  10
DLN  43  64  41  69 /  30  40  20   0
HVR  47  65  43  72 /  40  40  10  20
LWT  44  58  41  65 /  40  70  30  30

&&

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

$$

http://www.weather.gov/greatfalls