556 
FXUS65 KTFX 271738
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1130 AM MDT Thu Jul 27 2017

Aviation Section Updated.

.UPDATE...

Expanded isolated to scattered shower/thunderstorm coverage 
across nearly the entire forecast area this morning, as moisture 
continues to trend above normal with at least widespread weak (and
in some cases moderate) instability in association with an upper 
level disturbance overhead today. Cassell


&&

.SYNOPSIS...
A weak disturbance will bring a chance of showers and
thunderstorms through this evening. Some of the stronger storms 
could produce frequent lightning and strong wind gusts. A chance 
for showers and thunderstorms will continue into Friday though 
thunderstorms will not be as widespread. High pressure rebuilds on
Saturday. Temperatures will remain above average.

&&


.AVIATION...
Updated 1730Z.

Scattered cumulus clouds having bases around FL080 and mid-level 
ceilings will increase in coverage this afternoon as an upper-level 
disturbance approaches the area. Scattered showers and thunderstorms 
are expected mainly over southwest Montana affecting KEKS and KBZN, 
possibly extending toward KLWT this evening. Isolated showers and 
thunderstorms further north into central MT are less likely, but 
cannot be ruled out. VFR conditions prevail except for local MVFR 
ceilings near thunderstorms. 

&&

.FIRE WEATHER...
Scattered showers/thunderstorms will develop this afternoon and
evening, first over higher terrain and then move into the plains
and valleys. The main threat from any storms will be gusty erratic 
winds and frequent lightning. Downslope winds will also increase 
along the Rocky Mountain Front, which could lead to elevated fire 
weather concerns this afternoon and evening. Mainly dry and hot 
conditions will return this weekend and into next week. MLS

&&

.PREV DISCUSSION...
/ISSUED 530 AM MDT Thu Jul 27 2017/

Today through Saturday...Scattered showers and thunderstorms are 
possible today as an upper-level shortwave moves into the Northern 
Rockies. Thunderstorms will be a mix of wet and dry with gusty 
erratic winds and frequent lightning the primary threats. Most of 
the thunderstorm activity will develop over higher terrain initially 
and then move into the plains and valleys. On Friday, the chance for 
thunderstorms will persist but will mainly be confined to southwest 
Montana and the island mountain ranges across central Montana. The 
upper-level ridge of high pressure will re-build on Saturday with 
dry and very warm conditions anticipated statewide. An isolated 
thunderstorm is possible in the mountains across southwest Montana, 
however the threat is low. Temperatures will remain above average 
with highs ranging from the upper 80s across southwest Montana to 
low 90s over north-central Montana. MLS

Saturday night through Thursday...Unusually-strong high pressure 
ridging aloft will reside over the CWA during this period. 
Simultaneously, weather disturbances will traverse the ridge from 
west to east, particularly on Monday and Tuesday. As a result, a few 
showers and thunderstorms are possible each day. This is especially 
the case during the afternoon/evening hours and over/near higher 
terrain. A dry environment will allow new fire starts from lightning 
strikes to remain a concern. In addition, significant evaporation of 
rain should yield strong wind gusts in/near any shower or storm. 
Near-normal lows are expected during the period, while daytime highs 
will be about 5-10 degrees above-normal and easily reach the 90's 
for most locations. 
Jaszka

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  92  62  92  59 /  30  20  20  10 
CTB  90  57  89  53 /  20  20   0  10 
HLN  89  61  92  60 /  30  20  20  10 
BZN  84  56  87  54 /  30  30  30  10 
WEY  73  46  76  42 /  40  40  30  10 
DLN  80  54  83  53 /  40  40  30  10 
HVR  95  62  94  59 /  20  20  10  10 
LWT  86  62  89  57 /  30  20  20  20 

&&

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

$$

weather.gov/greatfalls