Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 222332
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
530 PM MDT Thu Jun 22 2017

...UPDATED AVIATION SECTION...

.SYNOPSIS...

A upper-level disturbance will lead to an increase in cloud cover
and spotty showers across northern and central Montana the rest of
this evening and into the day on Friday. However, clearing skies
over southwest Montana could cause temperatures to fall to near or
slightly below freezing tonight, so delicate plants there should be
covered or otherwise protected. There will then be a drying and
warming trend beginning this weekend and lasting through the early
part of next week. The next chance of showers and thunderstorms will
come with an approaching system from the west by late Monday and
into Tuesday.

&&

.DISCUSSION...
Tonight through Saturday...Cold front with light showers/sprinkles
continues to move southward through the region. With temperatures
falling into the falls and a brisk north wind...it does fell
chilly. Overnight lows will fall into the 30s in Southwest
MT...thus sensitive plants might need to be covered. Any snow
should be confined to ridge tops...mainly above 8000 feet.
Otherwise...a few showers continue into Friday along with
comfortable temperatures. The northwesterly flow aloft continues
over the region on Saturday...resulting in a few isolated showers.
Afternoon temperatures will be a touch warmer than Friday. Brusda

Saturday through Wednesday...Area remains under a NW flow aloft
Saturday as the large scale upper level trough progresses east across
the N-central CONUS. Though models are pretty limited in terms of
precip/coverage on Saturday, opted for at least slight chance pops
Saturday as embedded shortwave and upper jet energy combined with
somewhat unstable and cyclonic NW flow aloft should support some
afternoon shower and isolated thunderstorm development. Heights rise
Sunday and Monday as an upper level ridge briefly amplifies and
shifts east across the Northern Rockies and MT ahead of the next
trough from the NE Pacific approaching the West Coast. Afternoon
temperatures still slightly below seasonal averages Saturday warm to
above average by Monday and Tuesday of next week. Still a fair
amount of variability among models with the progression of the
Pacific trough inland by the middle of next week. However in any
case the upper ridge looks to weaken or be replaced by a weak trough
with an influx at at least limited moisture and shortwave energy
from the west/southwest for an increase in cloud-cover and potential
for afternoon shower/thunderstorm development. Hoenisch

&&

.AVIATION...
Updated 2330Z.

VFR conditions will mostly continue at least through the day on
Friday. A disturbance combined with weak instability will continue
the broken mid level cloudiness across the forecast area through
03Z. The best chance for showers during this time will be near the
Central Montana mountains (including the KHLN and KLWT terminals,
where brief MVFR ceilings are possible). Clouds and showers will
decrease as the airmass stabilizes after 03Z, but clouds will likely
increase again after 18Z as the airmass becomes weakly unstable
again. Gusty northerly winds will also decrease through the evening
as surface high pressure builds into the area from the north.
Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  41  68  44  70 /  10  10  10  10
CTB  40  66  43  68 /  10  20  20  20
HLN  43  72  47  74 /   0   0   0  10
BZN  37  71  42  72 /   0   0   0  10
WEY  31  67  35  69 /   0   0   0   0
DLN  38  72  43  72 /   0   0   0   0
HVR  41  71  44  74 /  10   0  10  10
LWT  39  65  40  67 /  10   0  10  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

weather.gov/greatfalls


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