Area Forecast Discussion
Issued by NWS Great Falls, MT

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492
FXUS65 KTFX 250500
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1100 PM MDT Tue Apr 24 2018

...Aviation Section Updated...

.UPDATE...

Current forecast is in good shape. High pressure will only allow
some high level cloudiness to pass overhead tonight. However,
forecast models are still on track to bring a mostly dry Canadian
cold front through the area during the day on Wednesday. Only made
minor adjustment to forecast grids to reflect observed
temperatures/wind/sky trends.
Coulston

&&

.SYNOPSIS...

Much warmer temperatures will continue through the upcoming
weekend with ample sunshine expected. Only feature to mention
this week will come on Wednesday, as a quick moving disturbance
and surface cold front will bring spotty showers across central
and south-central Montana by the afternoon and evening hours. The
next chance of rain and thunderstorms will arrive on Saturday,
which will be followed by a period of wet weather and cooler
temperatures into early next week.

&&

.AVIATION...
Updated 0500Z.

VFR conditions are expected through the mid morning hours on
Wednesday, as upper level ridging persists. The only noticeable
impact throughout the nighttime hours will be breezy winds along the
Rocky Mountain Front and mountains of Central Montana due to a
strengthening pressure gradient. These winds will primarily affect
the KCTB and KGTF terminals. A clipper system then drops southeast
from Southwestern Canada and across the Northern Rockies late
Wednesday morning and through the afternoon/evening hours. This
clipper system will drag a cold front across the region, shifting
and increasing southerly/southwesterly winds to the northwest/north.
While this system is not expected to bring significant amounts of
precipitation to the region, lowering ceilings and rain may bring
some terminals to MVFR conditions during the afternoon/evening hours
on Wednesday. Mountain obscuration is possible, especially across
the Central Montana Mountains where the best chance for
precipitation exists. - Moldan

&&

.HYDROLOGY...

The areal flood advisory continues for Meagher/Glacier counties
and the areal flood warning for Hill/Blaine counties continue.
Although many locations are reporting receding water, it is a
slow process and is likely to take a few more days.

The point flood warnings also continue for Lodge Creek at the
International Border/Milk River near Harlem. Both creeks continue
to fall. Lodge Creek is currently at flood stage, and it will
likely fall below flood stage overnight tonight. However, it will
take several more days before the Milk River falls below flood
stage.

Afternoon temperatures in the 70s to near 80 degrees later this week
will cause snowmelt to increase out of the mountains, which could
impact nearby creeks/streams. Scattered showers/thunderstorms are
also expected over the weekend, with the potential for a wet
spring storm early next week.

&&

.PREV DISCUSSION...
/ISSUED 535 PM MDT Tue Apr 24 2018/

We remain under the influence of a dominant area of high pressure
centered over east- central MT, which has led to clear skies and
breezy southwest winds this afternoon. A shortwave trough is
expected to push east across the northern Rockies early Wednesday
morning, along with a southward progressing cold front out of
southern Alberta. A few showers are possible in association with
the passing shortwave trough and surface front during peak diurnal
heating across central and south-central MT Wednesday afternoon,
before quickly exiting to the east early Wednesday night. The
departing shortwave trough will be replaced with a building ridge
across the northern Rockies, promoting even warmer temperatures
Thursday and Friday. Afternoon highs will likely soar well into
the mid to upper 70`s, with a few 80`s across the Plains.

The next focus will come on Saturday, as a stronger upper-level
low progresses across the PacNW and northern Rockies. The
combination of warm, unstable air in place along with supportive
upper-level dynamics will lead to the development of widespread
thunderstorms, some of which may be strong Saturday afternoon and
evening. Details will become more clear in the next few days in
regards to specific potential impacts.

The pattern remains rather active in the days following late this
weekend and into next week with several waves of showers
possible, along with cooler temperatures through the middle of
next week. KLG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  38  64  34  69 /   0  10  10   0
CTB  34  56  30  70 /   0  10   0   0
HLN  34  66  35  69 /   0  10  30   0
BZN  29  65  32  65 /   0  10  40   0
WEY  22  53  25  57 /   0   0  10   0
DLN  29  65  31  64 /   0   0  10   0
HVR  37  65  32  68 /   0  10   0   0
LWT  33  65  32  64 /   0  10  30   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

Flood highlights continue for portions of North-Central and
Southwest MT.

&&

$$

http://www.weather.gov/greatfalls



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