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FXUS65 KTFX 232050
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
250 PM MDT Wed Aug 23 2017

.SYNOPSIS...
With an upper level ridge moving east tonight and a weak upper
level trof approaching the region, a few isolated thunderstorms
will be possible over Southwest MT. The storms will become a bit
more widespread and also affect areas further northward on
Thursday. Afternoon highs for Thursday and Friday will be slightly
cooler than they have been, with highs in the upper 70s to lower
80s. However, warmer temperatures and dry conditions return over
the weekend and into the first half of next week.

&&

.DISCUSSION...
Tonight through Friday...The upper level ridge is moving eastward,
as a an upper level disturbance moves into Southwest MT. Most of
the storms this evening will affect areas mainly south of
I-90...but an isolated storm could develop as far north as the
Helena area. On Thursday, an upper level trof will move through,
cooling temperatures a bit and allowing for a slightly better
chance for storms to develop over portions of Central and
Southwest MT. A few of the storms will linger on Friday over the
eastern portions of the region...but much of the area will be
dry...along with seasonable temperatures. Brusda

Friday night through Wednesday...Overall a warming and dry
pattern will be found through the long term, with elevated fire
weather danger to continue. Friday night through Saturday we will
find ourselves in the wake of Thursday/Friday's disturbance. This
will bring weakly unstable zonal flow with a weak jet max
overhead. The result will bring some lingering chances for
showers and thunderstorms across southern and eastern portions
during this time period. A large area of high pressure will then
build across much of the western US starting Sunday and
continuing through at least the rest of the long term period. The
result will be warming temperatures and mainly dry conditions.
Afternoon RH values will continue to be low. This combined with
normal afternoon breezes may continue at least elevated fire
weather danger through the long term. A slight shift in location
of this high pressure on Tuesday and Wednesday may bring just
enough moisture and instability for isolated thunderstorms across
western and southern portions. With pwats expected to be low,
this looks to be mainly a dry thunderstorm threat, perhaps
further enhancing fire weather danger. Temperatures will start
near normal on Saturday, then start a warming trend with the
mentioned high pressure. Highs in the 90s are possible by next
week...especially Monday through Wednesday.
Anglin

&&

.AVIATION...
Updated 1754Z.
Smoke from neighboring wildfires will continue to limit
visibility across Central Montana this afternoon and evening. HLN
and GTF terminals may see temporary reduced visibility to below
MVFR at times, but generally should maintain VFR for the majority
of today. For these areas, major impacts include obscurations to
distant mountains/ridge tops through the evening. Otherwise,
expect spotty showers and a few thunderstorms across southwestern
areas. These will slowly drift to the east, but may build slightly
northward through the evening towards EKS and BZN terminals.
However, widespread heavy rain will be unlikely with any one
stronger storm containing dangerous lightning. Gusty westerly
winds will persist across CTB and HVR through the afternoon before
diminishing by late evening with all terminals sustaining VFR
through the overnight hours. KLG

&&

.FIRE WEATHER...
Red Flag conditions continue this afternoon along the I-15
corridor from Great Falls to Cut Bank. Expect slowly improving
conditions after 9 PM, but overall humidity should only have a
poor recovery overnight. On Thursday, thunderstorms are possible
but no highlights are planned for at this time. After some
slightly cooler temperatures on Friday, it then turns mostly dry
and warm again over the weekend and through the first half of next
week. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF 59 84 51 81 / 0 20 20 0
CTB 55 81 46 77 / 0 20 10 0
HLN 58 82 54 83 / 0 30 30 10
BZN 54 80 49 81 / 20 50 40 20
WEY 45 69 35 73 / 10 40 40 20
DLN 52 79 45 80 / 20 20 30 10
HVR 58 90 53 81 / 0 20 30 0
LWT 59 86 53 79 / 10 40 40 10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening Eastern
Glacier/Toole/Central/Eastern Pondera/Liberty...Lewis and Clark
National Forest Rocky Mountain District-Rocky Mountain Front...
Central and Eastern Lewis and Clark National Forest Areas.

&&

$$

weather.gov/greatfalls
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