404
FXUS65 KTFX 081143
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
543 AM MDT Wed May 8 2024

...AVIATION SECTION UPDATED...

.SYNOPSIS...

Rain and snow will decrease somewhat today over North Central
Montana, but warming air from the northeast may help some
scattered showers and thunderstorms to develop east of Interstate
15. Precipitation will continue off and on over and near the
Central Montana mountains and into Southwest Montana. Winds will
continue to be gusty into the overnight period as well. Overall,
high pressure aloft will help decrease precipitation tonight into
Thursday, bringing a warming and drying period for Friday through
the weekend.

&&

.DISCUSSION...

Key Points:

- Main adjustment was to add Rocky Mountain Front plains and
  Meagher County valleys to Winter Weather Advisory

- Precipitation will continue through today then decrease
  overnight into Thursday

- High pressure aloft will bring a warmer and drier period
  starting this Friday

Today through Thursday... Widespread rain and snow is starting to
decrease somewhat from the northeast early this morning. However,
evaporative / dynamic cooling from the heavier precipitation has
caused snow levels to fall to the surface on the plains adjacent
to the Rocky Mountain Front, on the north facing slopes of the
Central Montana mountains, and into the valleys of Meagher County.
Additional accumulating snow of mostly 2 to 5 inches with the
persistent gusty northerly winds will continue difficult driving
conditions across these areas this morning, so have expanded the
Winter Weather Advisory to include all of these areas. The
northerly winds are showing signs of decreasing, but gusts mostly
in the 40 to 50 mph range continue across the area, so will leave
the High Wind Warning in effect until 6 am today. Otherwise,
warmer low- to mid- level air is being advected into the area in a
northeast flow aloft between the low pressure trough exiting the
area to the southeast and a building high pressure ridge to the
northwest. This has resulted in a rising of the snow level over
Blaine, Hill, Chouteau, and northern Fergus Counties. This warming
should help weakly destabilize the airmass there this afternoon,
bringing the threat for some weak thunderstorms. However, the
moisture will continue to move over the area, keeping the threat
for additional measurable snowfall in the mountains, so will allow
the Winter Warnings and Advisories continue there into this
evening. Overall, precipitation and wind should decrease from the
northwest overnight into Thursday as the high pressure ridge
continues building into Montana. This should also help warm
temperatures back closer to normal on Thursday.

Friday through next Wednesday... Ensemble guidance in good
agreement with having the Pacific high pressure ridge remaining
the dominant weather feature for this period. Temperatures are
forecast to warm back above normal on Friday and up to 15 degrees
above normal for the weekend. Much of the period should remain
mostly dry, but a disturbance riding over the ridge may bring a
few showers and thunderstorms on Sunday. A shortwave trough is
then forecast to gradually break down the ridge Tuesday into
Wednesday, helping to cool temperatures a bit and bring an
increasing chance for showers and thunderstorms. -Coulston

&&

.AVIATION...
543 AM MDT Wednesday May 8 2024 (08/06Z TAF Period)

Steady rain and snow over North-central and portions of Southwest MT
will gradually diminish and more scattered in nature in a northeast
to southwest fashion, but MVFR/IFR/LIFR conditions will continue
through at least 09/06Z. Lower elevations will see snow through
around 08/15Z and then will switch back to rain. Strong gusty north
to northwesterly winds over the plains will slowly diminish through
the day. Expect widespread mountain obscuration for much of the
period as well as turbulence and instances of low level wind shear
through at least 08/18Z. - RCG

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

&&

.HYDROLOGY...

The recent heavy rainfall running out of the Bears Paw Mountains
has caused minor low-land flooding across Blaine, Hill, Chouteau,
and Fergus Counties, so a Flood Advisory remains in effect through
Thursday morning.

This rainfall will also cause area rivers and creeks to rise,
including Beaver Creek, Clear Creek, Peoples Creek, and Lodge
Creek. In fact, the forecast for Clear Creek has already risen
above Moderate Flood Stage as of 3 am; therefore, a Flood Warning
has been issued for that point until further notice. -Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  44  38  57  35 / 100  80  30   0
CTB  43  33  60  33 / 100  20  10   0
HLN  45  40  58  37 / 100  70  20   0
BZN  44  33  55  31 / 100  80  40  10
WYS  45  30  53  25 /  80  40  20   0
DLN  47  36  57  34 /  90  50  10   0
HVR  57  41  65  38 /  80  50  20   0
LWT  41  34  50  32 / 100  90  60  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 6 AM MDT early this morning for Cascade
County below 5000ft-Eastern Glacier, Western Toole, and Central
Pondera-Eastern Pondera and Eastern Teton-Eastern Toole and
Liberty-Fergus County below 4500ft-Hill County-Judith Basin
County and Judith Gap-Snowy and Judith Mountains-Western and
Central Chouteau County.

Winter Storm Warning until midnight MDT tonight for Big Belt,
Bridger and Castle Mountains-East Glacier Park Region-Gallatin
and Madison County Mountains and Centennial Mountains-Snowy and
Judith Mountains-Southern Rocky Mountain Front.

Winter Weather Advisory until noon MDT today for Cascade County
below 5000ft-Eastern Glacier, Western Toole, and Central Pondera-
Eastern Pondera and Eastern Teton-Fergus County below 4500ft-
Gates of the Mountains-Judith Basin County and Judith Gap-
Meagher County Valleys-Northern High Plains-Southern High Plains.

Winter Weather Advisory until 6 AM MDT early this morning for
Bears Paw Mountains and Southern Blaine-Eastern Toole and
Liberty.

Blizzard Warning until midnight MDT tonight for Little Belt and
Highwood Mountains.

Winter Weather Advisory until midnight MDT tonight for Elkhorn
and Boulder Mountains-Upper Blackfoot and MacDonald Pass.

Flood highlights in effect for portions of North Central MT.

&&

$$

http://www.weather.gov/greatfalls