Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 200254
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
854 PM MDT Thu Apr 19 2018

.UPDATE...
Updated forecast is out. No major changes. Just updated the
forecast to freshen pops. Took out pops north of Great Falls and
kept isolated showers along the border in Southwest MT.
Temperatures look on track.

&&

.SYNOPSIS...

Slightly warmer temperatures and lingering clouds will be found
across the region today. Mainly dry conditions are also
expected...although a few isolated to scattered rain or snow
showers are possible across the southwest. Clearing skies and
normal low temperatures are then expected for tonight. Friday will
then see mainly dry and warm temperatures...with some areas seeing
the return of 60 degree temperatures. A cold front then looks to
bring gusty winds and isolated to scattered showers on Saturday.

&&

.AVIATION...
Updated 2345Z.
VFR conditions with mostly clear skies will prevail over the region
through the period. Just some passing clouds this evening, but no
impacts are expected at this time. Brusda

&&

.Hydrology...
The areal flood advisory for Fergus county was cancelled this
evening as no additional reports of flooding were received and
satellite analysis shows little or no remaining lowland snow-pack
there. Areal flood warnings continue for Toole, Liberty, Hill and
Blaine counties where areas of snowpack linger and will continue
to contribute to runoff and flooding of lowland areas though the
next several days. Areal flood advisories continue for Glacier and
Pondera counties, where some roads are still being impacted by
lowland flooding but remaining lowland snowpack is minimal.
Numerous point flood warnings continue for the Milk River and its
tributaries across Hill and Blaine counties where additional
snowmelt and input from upstream tributaries will maintain
flooding through the next several days. With lessening snowpack
and dry conditions this weekend slow improvement is expected
across the Hi- line areas. A storm system early next week could
bring precipitation to southwest Montana. Hoenisch

$$

.PREV DISCUSSION...
/ISSUED 545 PM MDT Thu Apr 19 2018/
Tonight through Saturday...An upper level low continues to move
southward across the Great Basin this afternoon. Wrap around
moisture from this system could bring isolated/scattered showers and
possibly a thunderstorm to far southwest Montana this afternoon and
evening. Additionally, weak instability aloft could cause a brief
shower in central Montana this evening, although chances for this
are fairly low. Shortwave ridging aloft then builds over the region
for dry and warm conditions Friday and Friday night. It is possible
that some locations in the Great Falls forecast area could see their
first 60 degree day of this belated spring. By Saturday morning,
models indicate that a sharp upper level shortwave will approach the
forecast area. A surface low pressure system associated with this
system will develop in southern/central Alberta allowing downslope
pressure gradients to increase along the Rocky Mountain Front.
Surface winds along the front range and over the adjacent plains
will increase and, combined with passage of a surface cold front,
become strong and gusty. High wind criteria winds appear likely
along the Rocky Mountain Front and across eastern Glacier County.
Have gone ahead and issued a High Wind Watch for this region from
Saturday morning through Saturday evening. Remainder of north-
central Montana will also see windy and gusty conditions on Saturday
but it appears (for now) that they should remain below high wind
criteria. Along with the passage of the cold front, there could be
scattered showers over the western mountains and possibly an
isolated shower over the plains. mpj

Saturday Night through Thursday...The shortwave trough and Pacific
cold front will move east of the area Saturday night, which should
decrease the winds and move out any lingering showers. Weak high
pressure will then keep the area dry with near normal temperatures
for Sunday. Another shortwave with more of a Canadian cold front
will move southeast through the area Sunday night into Monday,
causing winds to shift more northerly and focus a good chance of
rain and snow over southwest Montana and southern portions of
central Montana. High pressure will move back into the area
temporarily Monday night into Tuesday, for drying conditions with
above normal temperatures. Forecast models then begin to diverge
with their solutions for the middle of next week. The GFS model
deepens a low pressure trough over Montana, the Canadian model
moves the trough into the Great Basin, and the ECMWF puts it off
the California coast, which keeps the forecast area under a high
pressure ridge. The GFS solution would bring the best chance for
precipitation, while the Canadian/ECMWF solutions remain generally
dry. Will therefore keep only a slight chance of showers in the
forecast until some consensus can be reached. Have also kept
temperatures close to or slightly above normal for Wednesday into
Thursday. Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  32  64  38  62 /   0   0   0  10
CTB  29  60  36  54 /   0   0   0  10
HLN  34  63  37  64 /   0   0   0  10
BZN  30  59  31  66 /   0   0   0  10
WEY  23  49  22  53 /  10   0   0   0
DLN  29  56  31  62 /   0   0   0   0
HVR  31  55  35  59 /   0   0   0  10
LWT  32  60  35  67 /   0   0   0  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Watch from Saturday morning through Saturday evening
Eastern Glacier...Northern Rocky Mountain Front...Southern Rocky
Mountain Front.

Flood highlights continue for portions of North Central MT.

&&

$$

http://www.weather.gov/greatfalls


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