820
FXUS65 KTFX 191536
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
936 AM MDT Fri Jul 19 2024

.SYNOPSIS...
Persistent upper level ridging over the Western US will help to
maintain well above normal temperatures and overall dry conditions
across Southwest through North Central Montana through the middle
of next week.

&&

.UPDATE...
Updated forecast is out. Only real change this morning was to
update the temperatures towards current trends, then limit
thunderstorm activity to mostly the Rocky Mountain Front area this
afternoon. Otherwise, the rest of the forecast is on track.
Brusda

&&

.AVIATION...
19/12Z TAF Period

VFR conditions are expected to prevail through the TAF period with
generally light winds. Isolated showers and thunderstorms are
possible this afternoon along the Rocky Mountain Front and in far
southwestern Montana but confidence in impacts for any terminals
remains too low to mention in the TAFs.

With regards to haze, there is a less than 20% chance for visibility
reductions at KEKS and KWYS. The difficultly in whether or not to
include the mention of haze in the TAFs was there is such low
confidence in the timing of any potential impacts. For the most
part, visibility at the terminals is not expected to be impacted so
given the low confidence in timing, haze was left out of this round
of TAFs. Otherwise, density altitude concerns from hot temperatures,
as well as slant range visibility concerns due to wildfire smoke
will continue this TAF period. -thor

Equipment Note: Due to a failure of the KEKS AWOS, no amendments are
scheduled until further notice.

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

&&

.PREV DISCUSSION...
/ISSUED 545 AM MDT Fri Jul 19 2024/

Today through Saturday...upper level ridge will amplify through the
first half of the weekend, with continued well above normal
temperatures and overall dry conditions expected across Southwest
through North Central Montana. Surface winds beneath this amplifying
ridge will remain overall light; however, infrequent wind gusts
during peak mixing may approach 15 to 25 mph. While most locations
will remain dry through the timeframe, isolated to scattered showers
and thunderstorms will be possible during the afternoon and evening
hours, most notably over the higher terrain on both days and east of
a Lewistown to Havre line on Saturday. Primary threat from any
shower or thunderstorm will be gusty and erratic winds given
inverted-V soundings.

Sunday through Wednesday...ensemble clusters continue to favor
strong upper level ridging residing over much of the Western CONUS,
with longwave troughing over the Pacific Northwest and western
seaboard of Canada. This upper level ridge will help maintain well
above normal temperatures and overall dry conditions across
Southwest through North Central Montana through the period. Leading
mode of uncertainty through the timeframe will be position and/or
timing of the aforementioned trough over the Pacific Northwest and
western seaboard of Canada, which will ultimately impact when the
upper level ridge over the Northern Rockies begins to be broken down.

Thursday through next Friday...ensemble clusters favor the breakdown
of the upper level ridge over the Northern Rockies as a longwave
trough slides east from the western seaboard. Leading mode of
uncertainty through the period will be the position and/or timing
of the longwave trough, which will ultimately impact how long the
above normal temperatures last across Southwest through North
Central Montana. None-the-less, ensemble model guidance does support
a brief and slight "cool down" towards the end of the work week as
upper level heights fall, but this may only result in daytime highs
reaching the mid- to upper 80s vs the preceding 90s to near 100
degrees. Additionally, as the ridge breaks down, expect southwest
to west winds to increase. - Moldan

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  93  60  94  59 /   0  10  10   0
CTB  92  55  94  57 /   0  10  20  10
HLN  98  60  98  60 /   0   0  10   0
BZN  95  54  95  54 /   0   0  10  10
WYS  86  42  85  42 /   0  10  20  10
DLN  90  52  90  51 /   0   0  10   0
HVR  96  61  97  60 /   0  10  20  20
LWT  88  56  88  55 /   0  10  30  20

&&

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

&&

$$

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