Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 190405
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1005 PM MDT THU AUG 18 2016

.UPDATE...

Vigorous upper level trough continues to dig south from Alberta
into N-central MT this evening. Back edge of widespread
precipitation across N-central MT is now working S of Hwy-2 as
drying behind the shortwave is already seen crossing the
US/Canadian border. A few thunderstorms continue to track east
along the I90 corridor in the more unstable environment ahead of
the shortwave trough axis. By midnight, expect the back edge of
precipitation shield to have reached Great Falls with
precipitation ending between Helena and Bozeman from 3am to 6am.
Isolated convection over SW MT may produce some marginal wind
gusts and small hail through midnight with intensity diminishing
thereafter. Gusty N winds will gradually diminish over northern
portions of the forecast area after midnight as high pressure
settles over the region but may continue through the overnight
period for areas S of I90. Hoenisch

&&

.AVIATION...
UPDATED 2335Z

Upper level trough digging south from AB into MT will spread
increasing moisture across the region tonight in NW flow aloft.
Widespread rain will spread S across N-central MT this evening and
central/SW MT late this evening through tonight. A few isolated
thunderstorms are also possible near the KHLN and KBZN terminals
early this evening before the more widespread precip arrives later.
Period of MVFR/IFR conditions likely at most terminals as the
precipitation spreads south across the area tonight with
precipitation ending from N-S late tonight, though lower ceilings
may continue into Friday morning before clearing Friday afternoon.
Hoenisch

&&

.PREV DISCUSSION...
/ISSUED 535 PM MDT THU AUG 18 2016/

Tonight through Saturday...Axis of an upper trof extending from
northern Manitoba through southwest Montana will swing across the
area overnight. Widespread lift over the area, and plenty of low
level moisture, will result in scattered showers and thunderstorms
this evening, continuing into early Friday morning. Southwest
Montana remains under the greatest threat for severe
thunderstorms. That area exhibits pockets of CAPE at 1000 J/kg
but shear is not too impressive. Across central Montana, areas of
heavy rain will be possible overnight. Snow levels will drop to
near 7000 feet overnight with light snow a possibility over the
higher peaks of Glacier National Park and over King`s Hill.
Precipitation begins to end from northwest to southeast late
Friday morning with clearing skies. 500 mb heights rise on
Saturday, ushering in a period of dry and tranquil weather.
Temperatures will remain below seasonal averages Friday but a
warming trend will commence on Saturday.

Saturday night through Thursday...A fairly quiet period of
weather is expected to begin over the weekend and continue through
the first half of next week. Expect mostly dry conditions with
warm temperatures from Saturday through Tuesday. By
Wednesday...both the GFS/EC hint at a cold front moving southward
into the region...but for now not much precipitation is associated
with the cold front. Thus low pops continue over North Central MT
but confidence is low right now in terms of pops. Temperatures
will be near normal for both Wed and Thu. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  45  68  45  81 / 100  20   0   0
CTB  41  69  46  80 /  90  10   0   0
HLN  49  69  47  82 / 100  20  10   0
BZN  48  68  40  80 /  90  40  10  10
WEY  46  63  31  71 /  30  20  10  10
DLN  48  69  42  80 /  30  20  10   0
HVR  47  70  47  81 /  90  10   0   0
LWT  45  65  45  76 /  90  60   0  10

&&

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

$$

weather.gov/greatfalls



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