Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 242308

Area Forecast Discussion
National Weather Service Great Falls MT
508 PM MDT Sun Jun 24 2018

...Updated Aviation Discussion...

A weak upper level disturbance will exit the region late this
afternoon with any lingering isolated showers and thunderstorms
ending. An upper level ridge of high pressure will then build
over the region for one day on Monday, resulting in a very warm
day. A Pacific cool front will move through the region on Monday
night, producing scattered thunderstorms and bringing with it
cooler temperatures for Tuesday. Some thunderstorms across north
central Montana Monday evening could be severe.



Tonight through Monday night...Upper level ridge is building into
the region from the west. However enough lingering low level
moisture and instability remains for a few isolated showers and
weak thunderstorms through the rest of this afternoon before
clearing occurs this evening. Much warmer and drier conditions
develop Monday as the ridge axis shifts east across MT with flow
aloft increasing from the SW. This will push afternoon
temperatures well into the 80s for most lower elevation locations
with breezy southwest winds developing in the afternooon as well.
By Monday evening the ridge axis will have shifted into eastern MT
with the the next upper trough moving into WA/BC with a fairly
vigorous surface cold front crossing the Northern Rockies. Models
have speed up this system enough for the front to cross the
continental divide Monday evening. This is a bit more favorable
for thunderstorm development and increases the potential for a few
severe thunderstorms with the frontal passage Monday evening
across north-central MT. At this point wind shear and instability
look to favor both the potential for isolated storms with
damaging wind and possibly large hail with fast enough storm
motion to limit any heavy precipitation to just a short duration.

Tuesday through Sunday....It turns cooler on Tuesday and mostly
dry behind the front. Expect a brisk westerly flow aloft over the
region for Wed/Thu, allowing for seasonable temperatures and
mostly dry conditions. The next upper level trof moves into the
region for Fri thru Sun, bringing with it a good chance for
widespread showers/thunderstorms along with cooler temperatures.
Afternoon highs next weekend could be near 10 degrees below
normal. Brusda


Updated 2308Z.

A few showers/weak thunderstorms may linger through 01-03z from KHVR
and KLWT east. Otherwise, high pressure building in from the west
and NW will bring clearing skies to all areas this evening through
tonight. VFR conditions with increasing SW winds are expected on
Monday, with a few thunderstorms possibly developing early Monday
evening (after 00z). CC


Scattered showers/thunderstorms will affect the region today and
again Monday night. Brief heavy rain is possible with the stronger
storms, especially on Monday evening. Another storm system will
affect the region Friday into Saturday. Widespread rainfall is
expected with this system, with rainfall amounts of 0.30 inches at
lower elevations to around an inch is possible in the mountains.

Specific County/River situations...

Fergus County...A Flood Warning remains effect for the Missouri
River at the James Kipp Campground. The river level has crested
but it will take another day before the river falls below flood

Flood Advisory for Toole/Pondera counties...This advisory
continues until further notice for areas around Shelby. Water is
slow to drain in this region, but conditions should improve by
this evening. Brusda


GTF  53  87  53  75 /  10   0  50   0
CTB  50  83  47  69 /   0   0  10   0
HLN  49  87  54  75 /   0  10  30   0
BZN  46  85  52  76 /  10   0  20  10
WEY  39  73  44  72 /  10   0   0   0
DLN  46  83  50  75 /   0   0  20  10
HVR  57  88  55  76 /  10   0  60   0
LWT  51  84  52  70 /  20   0  50  20



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