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000
FXUS65 KTFX 070020
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
520 PM MST Sat Mar 6 2021

...Aviation Section Update...

.SYNOPSIS...

Scattered rain and snow showers associated with a Pacific cold front
will diminish from west to east by midnight tonight. Some lingering
snow showers will remain possible during the overnight hours in the
southwest. Temperatures gradually cool Sunday into early next week,
with the potential for accumulating snow for some areas late Monday
into Tuesday.

&&

.DISCUSSION...

Remainder of this afternoon through Sunday Night...A Pacific cold
front is now moving through the central portions of North-central
and Southwest Montana, while its associated area of showers
crosses the Divide. This will move eastward and increase the
chance for showers of much of the region through this evening,
with locations south and east of a Helena to Havre line seeing the
best chances for measurable precipitation. There is a sliver of
100 j/kg CAPE currently sitting over Beaverhead County, though no
lightning has been observed so far. Still will continue to keep
the mention of thunder confined to that area, but keep in mind
that a lightning strike or two can`t be ruled out anywhere,
particularly in the southwest. Any snow with this system will
initially be confined to passes above 6000-6500 ft, where there
can be periods of reduced visibility, wet roads, and perhaps some
slushy accumulation. Snow levels are expected to fall to the
valley floors this evening and some lingering light snow showers
will be possible going into the overnight hours, especially in the
southwest. Temperatures are running quite mild this afternoon,
with most locations running about 10 to 20 degrees above the
seasonal average. Not expecting a big cool down behind the front,
but temperatures are forecast to be colder tonight, generally
ranging from the teens in the mountains and high valleys to the
20s and lower 30s elsewhere.

Fair weather follows Sunday into Monday morning as the region is
briefly influenced by upper level ridging. Temperatures will trend
cooler with highs in the 40s to middle 50s on Sunday falling to
the 30s and 40s Monday. RCG

Monday through Tuesday...

A large trough off the PacNW coast will become cut off from the
general circulation, with the main portion of energy diving into
southwestern states. However, a shortwave disturbance will eject
along the north side of a southwesterly jet streak across the
state of Montana Monday into Tuesday. A surface front will develop
within a favorable upper-level structure along the northwest side
of a developing surface low over southeastern Montana by Monday
evening. The result is likely to be a developing narrow corridor
of accumulating wet snow oriented southwest to northeast from
west- central to eastern north-central and northeastern Montana.
Given the dynamics and potential thermodynamics in play for a
brief period of time primarily Monday evening, expect much of the
precipitation to fall as snow even at lower elevations. This will
be in spite of temperatures likely starting off only marginally
cold in the upper 30s to lower 40s at precipitation onset. Model
ensembles seem to be in fairly high confidence in 0.10 - .25" or
higher liquid equivalent from around the greater Great Falls area
south to areas along and north of Interstate 90 in west-central
and central Montana. Snow accumulations up to a couple inches of
slushy snow will be possible, with higher amounts in the
mountains. Confidence in QPF and snow amounts fall off
significantly just to the north and south of these areas. RCG/CC

Wednesday through next Saturday...

The cooling trend levels off by the middle of next week as an
amplified northern stream disturbance and jet energy clip the
region. A fast-moving northwest-to-southeast cold front could bring
a very brief chance of snow especially along north-facing slopes
either Wednesday or Thursday. Temperatures are likely to warm at
least slightly again briefly toward the end of next week as
transitory upper ridging gives way to increasing west or
southwesterly upper flow. CC

&&

.AVIATION...
520 PM MST Sat Mar 6 2021 (07/00Z TAF period)

North-central Montana (KCTB and KHVR):

Expect VFR conditions with breezy to mildly gusty winds throughout
this aviation forecast period.

Central to Southwest Montana (KGTF, KLWT, KHLN, KBZN and KEKS):

Expect periods of MVFR conditions in rain/snow showers and mist.
Mountain obscuration and icing conditions are forecast. Additionally,
periods of gusty winds are forecast, with low level wind shear
conditions included in the KLWT and KBZN TAFs. Expect the associated
turbulence.
- Fogleman

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  29  53  27  42 /  30   0   0  20
CTB  28  48  26  41 /  20   0   0  10
HLN  30  52  29  43 /  20   0   0  30
BZN  28  52  25  46 /  80   0   0  30
WYS  15  42  14  45 /  40  10   0  30
DLN  25  48  25  45 /  30   0   0  40
HVR  30  52  30  47 /  20   0   0  10
LWT  28  50  26  43 /  60   0   0  20

&&

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

$$

http://www.weather.gov/greatfalls