049
FXUS65 KTFX 271229
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
628 AM MDT Thu Jun 27 2024

...Aviation Section Update...

.SYNOPSIS...

Strong thunderstorms are forecast for today. Some of these storms
may become severe, producing strong erratic gusty winds, large hail,
frequent lightning and heavy downpours. Temperatures cool through
the end of the traditional work week, with a few general
thunderstorms developing on Friday.

&&

.DISCUSSION...

Note: The forecast area for The National Weather Service Great
Falls Weather Forecast Office includes north central, central and
southwest Montana.

Today...An upper level trof rolls across The Treasure State,
today, with the attendant cold front impacting our region.
Considering the timing of cold frontal passage, thunderstorms
develop early and continue through the day. Some of these storms
may become severe. The Storm Prediction Center (SPC) includes,
Meagher, Judith Basin and Fergus Counties in an area of Slight Risk
for Severe Weather. For this area, there is a 15% to 29% risk for
severe wind of >= 58 mph, 15% to 29% risk for large hail of >= 1"
and 2% to 4% risk for tornado. Some other portions of our region are
included in a Marginal Risk for Severe Weather. Across these areas,
there is 5% to 14% chance for severe wind and a 5% to 14% chance for
large hail. These probabilities are considered within a 25 mile
radius at any given point in the risk area. All of today`s
thunderstorms have the potential to produce frequent lightning and
heavy downpours. The severe weather threat is forecast to move out
of our area by late afternoon. Cooler temperatures, follow.

Tomorrow...Low elevation high temperatures range about 10 degrees
Fahrenheit below normal. Rainfall impacts north central and
central Montana, allowing for some needed moisture. Strong gusty
winds are forecast, especially along The Northern Rocky Mountain
Front. Considering cold and wet conditions, hypothermia becomes an
concern to those working or recreating outdoors.

Saturday through next Thursday...An upper level ridge dominates
the first part of the weekend favoring warming conditions and a
dry day. Low elevation highs return to near normal values. With
the approach of the next upper level trof, the weather becomes more
active, again, with daily showers and thunderstorms forecast
from Sunday through next Thursday.
- Fogleman

&&

.AVIATION...
27/12Z TAF Period

Note: The NWS Great Falls Weather Forecast Office manages the
following TAFs: KCTB, KHVR, KGTF, KLWT, KHLN, KBZN, KEKS and KWYS.

KWYS begins this TAF period in LIFR conditons due to low visibility
in fog and low ceiling. These conditions are forecast to improve
after 27/14Z; otherwise, generally, VFR conditions are forecast.
MVFR conditions are included during periods of showers and
thunderstorms. Mountain-obscuring conditions are forecast with
widespread showers and thunderstorms associated with a cold frontal
passage between 12Z and 00Z. Most of these thunderstorms will be
capable of producing erratic gusts to 40KT, lightning, small hail,
and heavy downpours. Additionally, stronger thunderstorms are
forecast to occur along and east of a line from KHVR to KHLN to
KBZN, where gusts could exceed 45KT, at times, with large hail and
frequent lightning. In the wake of the cold front, showers and
storms will decrease, as breezy and gusty westerly winds become more
widespread.

Overall, the passing shortwave responsible for this thunderstorm
activity will keep a moderate westerly flow aloft over the area,
which will cause some mountain wave turbulence. Also, a low level
core of stronger southerly winds ahead of the shortwave will cause
low-level wind shear in far Southwest Montana (KEKS, KWYS) between
11Z and 16Z before the winds translate more down to the surface.
-Coulston/Fogleman

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  71  49  62  43 /  90  10  70  10
CTB  67  46  61  42 /  70  50  90   0
HLN  75  50  70  46 /  80  10  30   0
BZN  77  42  69  41 /  70  10  10   0
WYS  70  34  63  34 /  50  10  10   0
DLN  73  40  69  40 /  60   0   0   0
HVR  73  49  64  43 /  90  20  80  10
LWT  73  44  59  38 /  90  10  50  20

&&

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

$$

http://www.weather.gov/greatfalls