Helena Valley, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

242
FXUS65 KTFX 271502
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
902 AM MDT Fri Jun 27 2025

.KEY MESSAGES...

- Widely scattered showers and thunderstorms again today;
  otherwise, breezy to windy conditions and near average
  temperatures are expected through the weekend.

- Very warm to hot temperatures move in early next week, with
  daily rounds of showers and thunderstorms returning by mid-
  week.

&&

.UPDATE...

Today it will be warm with isolated showers and thunderstorms
with the strongest storms in Judith Basin and Fergus Counties. For
the update high temperatures across North-central Montana were
increased. Hourly temperatures across North-central, Central, and
Southwestern Montana were adjusted to better reflect current
observations and trends. Pops and QPF across Judith Basin and
Fergus Counties were increased to better reflect the latest hi-res
model guidance. The rest of the forecast is on track. -IG

&&

.DISCUSSION...
/Issued 551 AM MDT Fri Jun 27 2025/

 - Meteorological Overview:

Passing shortwaves within a southwesterly flow aloft will
maintain widely scattered showers and thunderstorms over the
Northern Rockies for one more day, with most of today`s activity
expected south and east of a Helena to Havre line this afternoon
and evening. Localized strong wind gusts will be the primary
concern with drier sub-cloud layers, but hail and brief downpours
can also be expected with the strongest storms in Judith Basin and
Fergus counties where moisture and instability will be a bit more
robust (precipitable water 0.75 to one inch/ML CAPE near 800
J/kg). Shower and thunderstorm chances drop off heading into the
weekend thanks to a shift to a drier westerly flow aloft.

The combination of deep layer mixing and stronger winds aloft
will bring breezy to windy conditions today and Saturday while
temperatures remain near average through the weekend. Ridging
aloft then boosts temperatures up to near 90 degrees for most
lower elevation locations by early next week with moisture and
subtle perturbations undercutting the ridge and interacting with
the summer heat for a return of daily scattered showers and
thunderstorms by the middle of next week. - RCG

 - Forecast Confidence & Scenarios:

Showers and thunderstorms this afternoon and evening...

Variable cloudiness and spotty shower activity will persist through
the morning over North-central and Southwest Montana, but the most
impactful showers and storms look to occur for areas south and east
of a Helena to Havre line this afternoon and early evening.
Localized strong wind gusts will be the primary hazard with forecast
soundings showing inverted V profiles and DCAPE values in the 700 to
1,200 J/kg range. Judith Basin and Fergus counties will have a
little higher instability and moisture, so any storms that develop
here will be more productive with hail and brief downpour potential
in addition to the wind threat. All in all expect isolated instances
of wind gusts over 50 mph and hail over the aforementioned areas.

Gusty winds today and Saturday...

Westerly surface winds increase over the next couple of days, with
the strongest winds expected along the Rocky Mountain Front and the
adjacent high plains west of I15 for both today and Saturday. These
areas have around a 50 to 70% chance for gusts over 45 mph. There
will also be windy conditions in other areas as well with the higher
terrain and the south the north oriented valleys of Southwest
Montana seeing gusts up to and exceeding 40 mph at times, especially
today. Plains locations east of I15 will generally see wind gusts in
the 30 to 40 mph range on both days. The primary impacts will be for
outdoor recreation on area lakes and camp grounds. Those traveling
with higher profile vehicles such as RVs and campers may experience
travel difficulties from the gusty winds.

Building heat next week...

Most ensembles favor ridging aloft to develop over the Northern
Rockies for much of the workweek next week. Probabilities for
afternoon temperatures exceeding 90 degrees increase to the 70 to
90% range for most lower elevation location by Tuesday afternoon.
The notable exceptions are the Cut Bank and Lewistown areas with
less than 50% chance for 90 degree exceedance. Confidence erodes
some for the Wednesday through Friday period with probabilities for
90 degrees or higher falling to the 10 to 40% range in all areas.
This uncertainty is from the expectation of increased shower and
thunderstorm activity. With that being said, newer deterministic
models are starting to increase temperatures and may begin to
increase temperatures probabilities if the upward trend continues to
gain traction. At the very least expect temperatures to generally
run 5 to 10 degrees above average for much of the workweek. - RCG

&&

.AVIATION...
27/12Z TAF Period

VFR conditions are generally expected for the TAF period;
however, a passing shortwave within a southwesterly flow aloft
will bring variable cloudiness and scattered light showers/virga
over North- central and Southwest Montana this morning. Then
widely scattered showers and thunderstorms develop this afternoon
and early evening, mostly south and east of a KHLN to KHVR line.
Some storms will bring brief localized gusts over 40 kts. - RCG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  82  52  79  48 /  20  10   0   0
CTB  74  49  73  45 /  20   0  10   0
HLN  81  53  80  50 /  40  10   0   0
BZN  86  49  82  47 /  20  20   0   0
WYS  75  40  75  37 /  20  10  10   0
DLN  81  47  80  44 /  10  10   0   0
HVR  84  54  79  48 /  20  10  10   0
LWT  78  50  74  47 /  50  30   0   0

&&

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

$$
http://www.weather.gov/greatfalls