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FXUS65 KTFX 250553
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1153 PM MDT Sat Aug 24 2019

...UPDATED AVIATION SECTION...

.SYNOPSIS...

A few weak showers and thunderstorms may still be found across
northern and central Montana through evening. Gusty westerly
winds will begin to diminish this evening, while near normal
temperatures are also found through tonight. The weather pattern
will shift cooler with gusty northwest winds Sunday into Monday,
and a chance of showers and thunderstorms during the afternoons
and evenings over the plains.

&&

.UPDATE...

Broad cyclonic circulation aloft will remain over the Treasure
State tonight and Sunday with weak disturbances in the flow
triggering isolated to scattered showers and thunderstorms at
times. Scattered storms continue to move eastward through the
region at mid-evening but most are expected to move out of the
forecast area by midnight. Partial clearing can be expected
overnight with another round of showers and thunderstorms
developing Sunday afternoon. Going forecast has a pretty good
handle on the situation and have only made minor adjustments to
PoPs for this evening using latest short term models and
observations. Have also made some changes to lower overnight
minimum temperatures in some locations, especially the valleys of
southwest Montana. No further updates are anticipated through the
remainder of this evening. mpj

&&

.AVIATION...
Updated 1153 PM MDT Sat Aug 24 2019 (25/06Z TAF)

A disturbance in the westerly flow aloft will keep a few light
showers near KBZN and a few weak thunderstorms near KHVR until
around 09Z. Otherwise, VFR conditions are expected through the next
24 hours, except for periods of MVFR conditions associated with
showers and thunderstorms. Another disturbance will move into the
forecast area from the northwest after 12Z, bringing widespread mid
level cloudiness to much of the area by 18Z. A weak Canadian cold
front will also move slowly south over North Central Montana (KCTB
KHVR) through 12Z, which will bring a period of gusty northerly
winds there. The combination of this frontal position and the
passing disturbance will bring mountain obscuration in widespread
showers and scattered thunderstorms to much of North Central and
Central Montana (mainly north of a KGTF-KLWT line) primarily between
16Z and 02Z. Clouds and showers/storms should decrease from the west
after 00Z. Coulston

&&

.FIRE WEATHER...

Some breezy winds will be found through the evening hours today,
although RH values are expected to be above critical values. Some
isolated shower and thunderstorm activity is also possible through
this evening, with gusty winds and some lightning being the main
threats. Precipitation should diminish shortly after sunset
tonight, with fair RH expected. Sunday sees a cold front push in
from the north bringing breezy northwest winds and cooler
temperatures. Scattered showers and thunderstorms are also
possible mainly across northern and central portions. Cool temps
from this front should bring improved RH values, hence fire
weather highlights are not expected at this point. Anglin

&&

.PREV DISCUSSION...
/ISSUED 520 PM MDT Sat Aug 24 2019/

Tonight through Monday...A weak disturbance embedded in westerly
flow is expected to bring some isolated shower activity through
this evening mainly across northern and central portions. An
isolated stronger storm is possible across the east, although
instability indicators are weak. Breezy winds and near normal
temperatures will also be found for most areas for the remainder
of the evening. Any precip should diminish or exit the area
tonight. Sunday then sees a cold front come down from the north
bringing cooler temperatures and breezy northwest winds. Some more
scattered shower and thunderstorm activity is possible with this
front mainly in northern and central portions, while southwestern
portions generally only see slight chances. An isolated stronger
storm is again possible in some areas, although instability and
shear parameters just not quite aligned and confidence for this
seems low to moderate at this point. Sunday night through Monday
then sees weekly unstable northwest flow with weak moisture moving
through. The result will be lingering chances for showers and
isolated thunderstorms in the north and central with little in the
southwest. Temperatures in the wake of Sunday's front will be
below normal and generally in the 60s and 70s. Breezy northwest
winds may also continue into Monday. Anglin

Monday night through Saturday...A broad upper level trough
initially extending from central Canada south into the Northern
Plains states gradually lifts out to the NE by mid to late next
week, allowing for some ridging to expand northward from the SW US
late next week before the next Pacific trough moves toward the
coast at some point next weekend. After a cool start on Tuesday
morning with some lows perhaps dipping into the upper 30s to low
40s, surface high pressure extending from the Canadian Prairies
south across MT will keep temperatures somewhat below seasonal
averages on Tuesday before a warming trend develops later next
week. Differences among individual forecast models exist with
respect to the amplitude of the ridging over the NW US as well as
the timing of weak shortwave features that may move through the
region late next week. National Blended Model guidance keeps
temperatures close to seasonal averages going into next weekend
but potential exists for somewhat warmer conditions if more
amplified ridging develops. Potential also exists for a few
showers or thunderstorms Thursday night and Friday as a weak
shortwave traverses the region with higher terrain areas of SW MT
more likely to see some of this activity. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF 52 73 48 65 / 10 20 30 30
CTB 50 67 45 61 / 10 70 40 30
HLN 52 75 45 72 / 10 10 10 10
BZN 48 77 41 74 / 10 10 10 0
WEY 41 73 32 71 / 0 0 0 0
DLN 48 75 39 72 / 0 0 0 0
HVR 53 70 48 67 / 30 50 50 50
LWT 51 70 44 63 / 30 20 40 40

&&

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

$$

http://www.weather.gov/greatfalls
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