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561
FXUS65 KTFX 162059
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
259 PM MDT Sun Jun 16 2024

.SYNOPSIS...

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Cooler than normal temperatures prevail, while the next weather
producer enters the region. Mountain snow and widespread low
elevation rain are forecast, through the early part of the coming
week. Low elevation high temperatures reach back into the 70s by
Thursday.
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&&

.DISCUSSION...

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Today and Tomorrow...Cool low elevation temperatures are forecast.
Areas of light rain are forecast north of the Hi-Line through this
afternoon. This evening, the next weather producer enters the
region, beginning with precipitation falling across southwest
Montana. The forecast is for low elevation rainfall, with
accumulating snow forecast at elevations, generally, above 6000
feet.
- Fogleman

Tomorrow, continued...Precipitation will become more widespread
and heavier Monday morning with the upper level low moving passing
through the region. There may be a few embedded thunderstorms
with precipitation on Monday/Tuesday afternoon due to a little
amount of instability present. Precipitation lingers into Tuesday
along another wave of passing through the region. Snow
probabilities in the mountains are between 30-50% for exceeding 8"
of snow. Considering the bulk of the snow being above pass level
and probabilities for accumulations to reach winter warning
criteria (9 inches) remain on the lower side, I have opted to
transition the Winter Storm Watches for mountain zones into Winter
Weather Advisories. Another change I`ve made to the winter
highlights is to move up the timing to 6pm Sunday to 6pm Tuesday
to account for the earlier start and end times for precipitation.
Greatest QPF amounts look to set up across Central MT, where they
hav.DISCUSSION... e around a 50% of exceeding 1". Most other lower
elevations across the CWA have at least a 50% of exceeding 0.25".
In terms of possible higher end QPF amounts, the 75th NBM
percentile ranges between 1.25-1.5" across Central MT and
0.35-0.75" across most other lower elevations.

With the upper level low bringing down colder air, cold overnight
temperatures are forecasted for Monday and Tuesday morning.
Tuesday morning wind chills in the mountains can drop down to the
teens and 20s. Those in the backcountry should prepare for
cold/raw conditions.

Wednesday and looking beyond...The main upper level low will move
off to the east, and a zonal/southwest flow aloft pattern will
settle in behind for the remainder of the week. There looks to be
enough moisture around and small disturbances that passes through to
keep low chances of precipitation daily. With the southwest flow
aloft bringing in warmer air, temperatures will gradually warm up
through the weekend. By Saturday, lower elevations have a 60-80% of
high temperatures reaching 80 degrees or higher. -Wilson
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&&

.AVIATION...
16/18Z TAF Period

VFR conditions are expected to prevail through midnight or so across
North Central and Southwestern Montana, with some gusty winds from
KHLN north. Expect clouds to gradually thicken today, with MVFR cigs
beginning to become possible around/after midnight with rain and
mountain snow developing. After midnight, expect periods of MVFR to
IFR conditions as low cigs and rainfall spread across North Central
and Southwestern Montana, along with mountain obscuration. Ludwig

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

&&

.PRELIMINARY POINT TEMPS/POPS...
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GTF  42  49  40  57 /  40  90  80  80
CTB  37  53  37  55 /  20  80  60  70
HLN  44  54  42  63 /  60 100  80  80
BZN  41  56  37  59 /  30  90  90  70
WYS  38  52  30  52 /  20  70  70  60
DLN  39  52  34  56 /  30  90  70  50
HVR  42  57  42  61 /  10  90  70  60
LWT  38  52  35  55 /  30  90  90  80
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&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 6 PM this evening to 6 PM MDT
Tuesday for Big Belt, Bridger and Castle Mountains-East Glacier
Park Region-Elkhorn and Boulder Mountains-Gallatin and Madison
County Mountains and Centennial Mountains-Little Belt and
Highwood Mountains-Northwest Beaverhead County-Southern Rocky
Mountain Front.

&&

$$

http://www.weather.gov/greatfalls