Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 200421
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1020 PM MDT Fri May 19 2017

...UPDATED AVIATION SECTION...

.UPDATE...

Little needed updating this evening. A weak wave is moving across
northern portions of the state currently producing isolated
showers. Adjusted pops only slightly to account for current radar
trends...with precip chances diminishing quickly after midnight
tonight. Saturday`s wave showing up nicely on WV right now off the
WA coast...with quite the swath of moisture available. The result
will be more widespread showers for Saturday afternoon and
evening mainly along and east of a line from Havre to Lewistown to
Billings. A few thunderstorms are possible...especially across
the northern half of our CWA...however...low amounts of shear will
keep storms below severe criteria...with lightning...gusty
winds...and small hail being the main threats. Anglin

&&

.SYNOPSIS...

A weak upper level disturbance continues to move southeastward
through the region this afternoon. A few light showers and
isolated thunderstorms are possible this evening as the
disturbance moves through. A repeat of these conditions is
expected on Saturday, except the thunderstorm activity will be a
bit more widespread, especially during the afternoon and evening
hours. Looking ahead, several days of no precipitation and warm
temperatures are expected for the middle portion of next week.

&&

.AVIATION...
Updated 0420Z.

VFR conditions are expected through the next 24 hours. Scattered
mid/high clouds will persist over the area under a northwesterly
flow aloft. An isolated shower may hold together long enough to
affect KHVR until 08Z. Otherwise, a disturbance will move into the
area after 15Z, spreading scattered showers and isolated
thunderstorms across the area once again. Ceilings may lower to near
MVFR levels briefly, and wind gusts up to 30 kt will be possible.
Shower/thunderstorm activity will decrease from the north after 00Z
as the disturbance begins exiting the area.
Coulston

&&

.PREV DISCUSSION...
/ISSUED 510 PM MDT Fri May 19 2017/
Tonight through Saturday...With a weak upper level disturbance
moving southward through the region this evening, expect isolated
showers/thunderstorms early this evening. On Saturday, a repeat of
these conditions are expected, except the thunderstorm activity
looks to be a bit more widespread than today. Thus pops are a bit
higher. Precipitation amounts from the showers should generally
range from a few hundreths to around a tenth of an inch in heavier
showers. Afternoon temperatures will be seasonable on Saturday.
Brusda

Saturday Night through Friday...Unsettled northwesterly to
northerly flow aloft is expected Saturday night through Monday,
with a pronounced shortwave trough progged to drop southward over
our CWA Monday morning through afternoon. Thus, isolated showers
and thunderstorms are possible during this time. An overall
drying trend is then expected Tuesday and Wednesday as upper-
level ridging builds eastward over our region. The potential of
scattered showers and isolated afternoon/early evening
thunderstorms looks to increase Thursday and Friday as an upper-
level trough may begin to break- down the aforementioned ridge.
Low temperatures will be near or slightly above-normal during the
period. Highs will moderate from slightly below-normal Monday to
above-normal by Tuesday and especially Wednesday. Highs may then
cool to near- normal values by Friday. Jaszka/Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  41  64  41  67 /  10  40  30  10
CTB  40  64  40  67 /  30  30  20  10
HLN  43  64  43  70 /  10  40  40  10
BZN  37  61  38  64 /  10  40  40  20
WEY  26  47  30  55 /  10  40  40  20
DLN  35  56  39  63 /  10  30  30  20
HVR  41  70  42  71 /   0  30  20  10
LWT  38  61  40  64 /   0  30  20  10

&&

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

$$

weather.gov/greatfalls


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