Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 221755
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1155 AM MDT SUN MAY 22 2016

UPDATED AVIATION SECTION

.DISCUSSION...
For the update, dropped wind gusts a bit along the Rocky Mtn Front
as cloud cover may help to limit mixing some this afternoon. Still
looks like a breezy afternoon for much of the area, though.
Dropped afternoon highs a bit along the Front as well as clouds
this morning will likely hang tough there through this afternoon,
keeping it a bit cooler than originally thought. For this
afternoon/evening, still expect isolated to scattered
showers/storms. Shear/instability isn`t nearly as impressive as
recent days, but with an inverted-V sounding environment and
steep lapse rates, gusty outflow winds will be possible with any
shower/storm, especially east of a Dillon to Great Falls to Havre
line. Martin

&&

.AVIATION...
UPDATED 1755Z.
Southwest flow aloft will continue to bring moisture and mid to high
clouds across the area. Southwesterly surface winds have increased
and will remain gusty beyond 00z. Scattered to isolated showers
and/or thunderstorms will develop after 20z and end by 04z. VFR
conditions prevail with MVFR conditions possible in the vicinity
of showers and/or thunderstorms along with gusty erratic winds.

&&

.HYDROLOGY...
Periods of showers and isolated thunderstorms will continue to
affect the region over the next few days. A Flood Warning
continues for Clear Creek where the level this morning was still
just above flood stage. It is expected to drop below flood stage
by this evening. Meanwhile, other locations near small creeks
could see minor low land flooding or agricultural field flooding.
However, with breaks in the precipitation, major rivers/creeks are
not expected to rise above flood stage at this time.
Brusda/Martin

&&

.PREV DISCUSSION...
/ISSUED /
TODAY THROUGH TUESDAY...Much of the region will be in transition
today, with breezy and sunny skies this morning, giving way to
windy and showers redeveloping this afternoon. Some fog has
developed over the Plains of North Central MT early this morning,
but much of the fog should burn off by mid morning as
southwesterly winds develop. A slow moving upper level low will
reside over southern Canada over the next few days. As a
result...strong west winds will develop over North Central MT by
mid day. I kept forecasted wind gusts just below warning criteria
along the I-15 corridor from Great Falls to Cut Bank, but the
potential exists that the Cut Bank area may need a wind highlight
later today. Scattered showers should redevelop this afternoon,
mainly over Southwest MT and for areas east of I-15. Over the
Rocky Mountain Front...heavy snow is possible in the mountains as
a moist westerly flow causes upslope west of the divide, and some
of the precipitation will spread just a few miles east of the
divide. Afternoon temperatures today will be a bit warmer than
they have been because of the west winds and some morning
sunshine. For tonight through Tuesday...scattered showers and
below normal temperatures are expected during this period. The
downslope winds will be much lighter...thus the scattered showers
will become a bit more widespread. With sky cover becoming mostly
cloudy, temperatures will generally be below normal Mon/Tue.
Brusda

TUESDAY NIGHT THROUGH SUNDAY...Forecast models continue to show an
unsettled period during this time, with the greatest potential for
showers and thunderstorms occurring during the peak instability of
the afternoon and early evening hours. A broad upper level trough
with two distinct low pressure areas will set up over the western
and central United States through Friday. One low pressure area will
move east across the southwestern U.S. during this period, while the
second one dives south along the Pacific Northwest coast. A
disturbance over Montana and southern portions of Alberta and
Saskatchewan will keep a chance of showers and thunderstorms over
the forecast area through Wednesday night, with the best chances
over western and southwest Montana. As this disturbance moves east
out of the area with the first low pressure center beginning on
Thursday, the second low will continue to move south over the
Pacific Coast states and a high pressure ridge will build over the
Great Plains. As a result, the flow aloft will become more
southerly, which will bring unstable and steadily warming air with
increased (potentially monsoonal) moisture to Montana. This will
continue the good chance of showers and mainly afternoon/evening
thunderstorms over the forecast area. Temperatures will remain near
normal for most of the period, but warming temperatures into the
Memorial Day weekend could cause highs to reach the lower to mid 70s
in some areas by Sunday. However, with this warming, there will be
an increased threat of strong thunderstorms over the weekend. Will
continue to monitor this situation. Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  62  43  52  40 /  10  20  40  30
CTB  53  40  49  37 /  20  40  60  40
HLN  62  43  54  42 /  30  20  40  20
BZN  60  38  57  38 /  20  30  40  30
WEY  46  31  48  33 /  40  40  40  30
DLN  56  36  56  37 /  40  20  40  20
HVR  63  44  56  42 /  20  40  50  30
LWT  60  41  56  39 /  20  20  30  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon MDT Monday for MTZ009-048.

Flood Warning for Clear Creek in Blaine County through Sunday
night.

&&

$$

weather.gov/greatfalls



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