Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 191153
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
553 AM MDT Thu Apr 19 2018

...UPDATED AVIATION...

.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.

&&

.DISCUSSION...

Today through Saturday...Overall a quiet and warming pattern is
expected to end the work week...with a mainly dry cold front
possible on Saturday. A large upper low will pass to our south
today...bringing some increased cloud cover...and perhaps some
low impact scattered rain or snow showers across far southwestern
portions. Near normal temperatures in the 40s and 50s are also
expected today. This low will push eastward tonight into
Friday...leaving us in between systems. The result will be
continued warming temperatures...clearing skies...and mainly dry
conditions. Some areas could see the return of 60 degree
temperatures on Friday...which for some are approaching record
latest time of the year for the first 60 degree day. Saturday`s
weather will then be driven by a sharp...but mainly dry...cold
front that will pass across the state from west to east. Shower
activity from this front will be limited to the western
mountains...and perhaps an isolated shower across the plains.
Strong winds from this front are possible...especially across the
plains and the Rocky Mountain Front. Models showing 700 mb wind
over 50 Knots. With a sharp front like this...it would be easier
to mix down these winds to the surface. Will have to be monitored
for a High Wind Watch...especially for the Rocky Mountain Front
Zones and adjacent high plains zones. This down sloping wind will
bring further warming conditions for Saturday...with perhaps some
70s possible across the east. Warm temperatures will once again
bring hydro concerns for melting snow. See the Hydro Discussion
for more details. Melting snow could also help saturate the air at
night...perhaps bringing some patchy fog...especially Friday
morning. Saturday may also present some fire weather concerns for
those doing some spring ag burning as RH will be moderately
low...and strong winds will accompany the front. Although critical
fire weather conditions are not expected...those burning may want
to delay any operations on Saturday to a less windy day.

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 showers more so over central and southwest Montana.
Light measurable snow is possible in the central and southwest
mountains as temperatures fall just below normal. 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

&&

.AVIATION...
Updated 1200Z.

VFR conditions will prevail through today as a weak disturbance
passes to the south of Montana. Generally dry conditions...partly
cloudy skies...and eastern winds are expected for
today...although some scattered shower activity is possible across
far southwestern Montana. Mainly dry conditions and light winds
are expected for tonight. Some areas could see patchy fog develop
late tonight into early Friday morning. Confidence remains
low...and have placed in VCFG for sites with the best chances.
Otherwise VFR conditions should prevail for tonight. Anglin

&&

.HYDROLOGY...
Updated 840 PM Wednesday (4/18).

Flooding continues to affect northern and northeast portions of
north-central MT this evening with flood warnings for several
points along the Milk River and its tributaries in Hill and
Blaine counties as well as countywide for smaller creeks. Areal
flooding from creeks and snow-melt is also impacting areas further
west across Liberty, Toole and Pondera counties. Satellite
imagery this afternoon still shows a significant though dwindling
snowpack in portions of these counties with additional run-off
likely to continue to produce hydrological issues through the next
several days as temperatures gradually warm. New point flood
watches will be issued this evening for Lodge Creek in northeast
Hill county and The Missouri River at Landusky (near the Fred
Robinson Bridge) where river stage measurements are increasing and
may reach flood stage in the next 24 hrs. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  57  32  64  39 /  10  10   0   0
CTB  53  29  61  36 /  10  10   0   0
HLN  58  33  63  38 /  10  10   0   0
BZN  56  29  60  33 /  10  10   0   0
WEY  47  22  50  22 /  20  20   0   0
DLN  54  28  57  32 /  20  20   0   0
HVR  56  29  56  35 /  10  10   0   0
LWT  56  31  60  36 /  10  10   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

Flood Warning in effect until further notice
for Big Sandy Creek near Havre.

Flood Warning in effect until further notice
for Milk River near Havre.

Flood Warning in effect until further notice
for Battle Creek near Chinook.

Flood Warning in effect until further notice
for Milk River near Harlem.

Areal Flood Warning in effect until 815 PM MDT Sunday
for Hill...Blaine Counties.

Areal Flood Warning in effect until 445 PM MDT Monday for
Liberty...Toole Counties.

Areal Flood Advisory in effect until 345 PM MDT Friday
for Glacier County.

Areal Flood Advisory in effect until 815 AM MDT Thursday
for Teton County.

Areal Flood Advisory in effect until 715 AM MDT Friday for Fergus
County.

Areal Flood Advisory in effect until Noon MDT Friday
for Eastern Pondera County.

&&

$$

http://www.weather.gov/greatfalls



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