969
FXUS65 KTFX 201003
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
403 AM MDT Thu Jun 20 2024

.SYNOPSIS...

There`s a chance for some isolated showers/thunderstorms this
afternoon. Better chances for precipitation across Central and
North Central MT arrive Friday. There`s a potential for a few
strong to severe storms Friday afternoon. Drier and warmer
conditions arrive for the weekend and beginning of next week,
with well above average temperatures.


&&

.DISCUSSION...

Today...With clear skies and calm winds, there may be some patchy
fog development this morning for portions of Central/North
Central MT where locations received rain yesterday evening. 500mb
height rises along with southwest flow aloft will continue to
bring warmer temperatures to the region. Lower elevations will
reach into the 70s this afternoon. Another small shortwave moving
through this afternoon will also produce some isolated
showers/storms across Central/North Central MT. Precipitation
looks to be light overall, with most places seeing 0.10" or less
of moisture (could see locally higher amounts if a heavier
shower/storm sets up).

Friday...Better forcing for precipitation arrives on Friday as a
compact shortwave trough moves through the region. Model guidance
shows some higher instability (1,000-1,500 J/kg of CAPE with
localized areas up to 2,000 J/kg of CAPE) and better shear(~40kts
of bulk shear) setting up to have the potential of a few strong
to severe storms during the afternoon (best chances along
Central/North Central MT). The primary threats will be hail and
strong wind gusts. The Storm Prediction Center has a "General
Thunderstorm" risk for Friday, however I can not rule out the
potential for an isolated supercell. We will continue to monitor
these chances for some stronger to severe storms with future
shifts. Best chances for precipitation looks to set up in
Central/North Central MT. Showers/storms can produce localized
areas of heavy rainfall, with model guidance targeting the Bear`s
Paw region for highest amounts of rain accumulations. There`s a
40-60% of Chouteau, Fergus, Hill, and Blaine counties receiving a
half inch or more of precipitation. For higher end amounts, the
75th percentile NBM has the Bear`s Paw region receiving up to
1-1.25" of precipitation if they get a heavier shower/storm.

Saturday and Beyond...Dry conditions return Saturday as upper
level ridging returns. Temperatures will go well above normal,
with lower elevations possibly reaching the 90s for the first
time this year on Sunday afternoon. Ensemble clusters indicate the
ridging to last for the first half of next week which will lead
to drier and warmer conditions. Ensemble clusters diverge by
Wednesday with the strength of amplitude of the ridge. This
suggests either the drier and warmer weather sticks around, or
cooler and wetter weather returns. -Wilson

&&

.AVIATION...
20/06Z TAF Period

Isolated showers across the eastern and northern plains of North
Central Montana will continue to dissipate through the early morning
hours on Thursday. Main impact from these showers would be
reductions in CIGS to low-VFR. Otherwise, the primary concern
through the TAF period will be the potential for patchy fog
development, particularly near the KGTF terminal. Hi-Res Ensemble
Forecast guidance gives the KGTF terminal a 10-20% chance for
reduced VIS from fog between 08-14z Thursday, but given the low
probabilities only a tempo group has been used at this time. VFR
conditions will otherwise prevail throughout the 2006/2106 TAF
period, with isolated to scattered showers and storms developing
after 18z over the plains of Central and North Central Montana. -
Moldan

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  75  50  75  49 /  10  10  60  20
CTB  72  45  72  44 /  20  10  70  20
HLN  79  53  83  52 /  10  10  40  10
BZN  75  47  80  49 /   0   0  30  10
WYS  71  40  74  41 /   0   0  20  10
DLN  73  45  81  47 /   0   0  10   0
HVR  76  51  75  50 /  10  20  90  50
LWT  72  47  72  48 /  30  20  80  40

&&

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

$$

http://www.weather.gov/greatfalls