Area Forecast Discussion
Issued by NWS Great Falls, MT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KTFX 271120
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
520 AM MDT SAT AUG 27 2016

AVIATION SECTION UPDATED

.DISCUSSION...

Today through Monday...Weak upper level disturbances embedded in a
westerly flow aloft will maintain mostly cloudy skies today.
Although a few echoes may appear on radar, precipitation is not
expected at the surface due to the dry and downslope west-
southwest flow. A weather system crossing the Canadian Rockies
today will produce a period of gusty winds for North-central MT.
The combination of these winds and low relative humidity creates
elevated fire weather concerns this afternoon. A weak cold front
will advance through north-central MT tonight, returning
temperatures closer to seasonal averages on Sunday. Dry
conditions prevail through Monday with broad ridging aloft over
the northern Rockies. Temperatures in southwest MT remain above
average. PN

Monday Night through Saturday...Period begins with dry and very warm
conditions as high pressure ridge that was over us on Mon drifts
into the Dakotas on Tues. This puts our forecast area in the warm
southwest flow aloft on the west side of the ridge, pushing high
temps back into the upper 80s and low 90s on Tues aftn. Remnants of
the ridge will linger over central MT into Wed, but from midday Wed
into the weekend, our main weather-maker will be the broad Pacific
trof that will extend from the AK/BC coast all the way to southern
California.  Minor shortwaves moving through the southwest flow ahead
of the trof axis will combine with a mix of Pacific and monsoonal
moisture to generate isolated to scattered thunderstorms each aftn
from Wed-Fri.  Models still struggling to find agreement on when the
main portion of the Pacific system will come ashore and how much
moisture will accompany it.  In yesterday`s model runs, the GFS was
slower in advancing the trof inland, but is now fairly similar to
the ECMWF solution for timing, but is considerably wetter than the
ECMWF on precip coverage and amount. Latest forecast raises the
probability of precip on Saturday, with 25-35% values covering the
entire county warning area through Sat night. Temperatures will
trend steadily downward through the latter half of the week as each
succeeding shortwave passage brings increased cloud cover and
slightly cooler air down from Canada.  Highs will be back in the
mid 80s by Thurs and the low 70s by Sat.
Waranauskas

&&

.AVIATION...
UPDATED 1120Z.
West to northwest winds aloft will keep steady flow of Pacific
moisture across central/southwest MT today.  This will result in VFR
conditions with widespread BKN-OVC mid- and high-level clouds for
much of the day and into this evening.  Despite all the clouds, the
region will remain dry today, as no rainfall is forecast at/near any
TAF sites. Surface winds will be breezy (gusts 20-30 kts) from late
morning through early evening as a leeside trough forms over
southern Alberta and north central MT.  Winds will dissipate by 02-
03Z as pressure gradient from the trough weakens.
Waranauskas

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  84  56  80  52 /   0   0  10  10
CTB  79  50  72  47 /   0   0   0  10
HLN  84  56  83  54 /   0   0  10  10
BZN  85  48  85  48 /   0   0   0   0
WEY  72  39  74  41 /   0   0   0   0
DLN  81  47  83  47 /   0   0   0   0
HVR  86  55  77  52 /   0   0   0  10
LWT  82  53  80  52 /   0   0  10  10

&&

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

$$

weather.gov/greatfalls


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.