292
FXUS65 KTFX 271942
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
142 PM MDT Tue May 27 2025
.KEY MESSAGES...
- Temperatures moderate through Thursday before a passing
disturbance bring a slight reprieve from the above normal
temperatures on Friday.
- Isolated to scattered showers and thunderstorms, a few of which
could become strong, are expected Thursday afternoon and
evening.
- Well above normal temperatures and dry conditions will occur on
Saturday, with a cooler and wetter pattern developing into
early next week.
&&
.DISCUSSION...
- Meteorological Overview:
Upper level ridging will quickly begin to build back in across the
Western CONUS through Thursday morning before a potent, but fast,
moving shortwave lifts northeast from the Pacific Northwest (Thursday
morning) and over the Northern Rockies (Thursday afternoon/evening).
This shortwave will briefly help to flatten the ridge for the day on
Friday, with the ridge rebuilding through the first half of the
weekend ahead of a longwave trough which then looks to dig in across
much of the Western CONUS for the second half of the weekend and
early next work week.
High temperatures look to moderate slightly for the day on Wednesday
beneath the building ridge, with temperatures warming significantly
on Thursday as a strong surge of warm air is advected in across the
Northern Rockies. Temperatures on Friday, while still being 5-10
degrees above normal, cool thanks to the brief flattening of the
upper level ridge, but then rebound 10-15 degrees for the day on
Saturday. At this time it looks like Saturday will be the warmest
day of the upcoming week as temperatures peak in the mid-80s to low
90s before beginning to cool slightly on Sunday and more
significantly (i.e. well below normal) on Monday and Tuesday as
longwave troughing begins to become established across much of the
Western CONUS.
While a few showers and thunderstorms can`t be ruled out over the
higher terrain along/near the Idaho/Wyoming borders on Wednesday
overall dry conditions are expected beneath the building ridge.
These dry conditions look to persist through the first half of the
day on Thursday before the approaching shortwave from the Pacific
Northwest and an associated Pacific front help to spark off showers
and thunderstorms, a few of which could be on the strong side,
during the afternoon/evening hours on Thursday. A return to overall
dry conditions is then expected from Friday through Saturday, with
increasing precipitation chances thereafter as an abundance of
Pacific, and potentially tropical from the Baja of California,
moisture begins to overspread the Western CONUS. - Moldan
- Forecast Confidence & Scenarios:
Showers and thunderstorms Thursday evening...
Scattered showers and thunderstorms are expected to develop along
an eastward advancing cold front Thursday evening. The primary
concern will be gusty thunderstorm winds with very warm and dry
surface conditions ahead of the front and cold air advection and a
stronger wind profile aloft behind the front. Forecast soundings
already show DCAPE levels above 1,000 J/kg and this combined with
the cold front being supported by the colder air and stronger
winds aloft theoretically increases the risk for showers and
thunderstorms transferring stronger wind gusts to the surface.
Probabilistic guidance and other anomaly indicator indices have
not latched on to this yet with merely a 50 to 60% chance for
gusts exceeding 45 mph along the Northern Rocky Mountain Front and
the adjacent high plains west of I15. Locations along the Hi-Line
will be most susceptible to the stronger gusts where shortwave
forcing and winds aloft will be greatest. This situation will
continue to be monitored. - RCG
Cool and wet conditions early next week...
Very warm and dry conditions more or less persist through Sunday
before a trough deepens over the Pacific Northwest and sends a
cold front moving through Montana sometime Sunday afternoon or
evening. A round of showers and thunderstorms can be expected
during the transition, with a few storms being on the stronger
side given the very warm conditions ahead of the front. Around 80%
of ensemble members support the Pacific Northwest trough moving
eastward into the interior west and bringing widespread
precipitation and well below average temperatures during the first
part of next week; however, the fact that this system will be
closed low with more trek predictability issues, compared to open
waves more aligned with the jet stream, has lead to a number of
positioning and timing solutions to sort out. With that being
said, NBM probabilistic guidance is already beginning to support
widespread rainfall amounts between a quarter and three quarters
of an inch over much of Central and Southwest Montana between
Monday morning and Wednesday morning with most of these areas
currently have a 40 to 70% chance for exceeding a half inch of
rainfall during this timeframe. - RCG
&&
.AVIATION...
27/18Z TAF Period
Main concern will be the small chance for a passing
shower/thunderstorm over far Southwest MT, affecting mainly the
West Yellowstone terminal late this afternoon. Most of the
precipitation exits the CWA early this evening. Otherwise VFR
conditions are expected across the rest of the CWA through the
period. Brusda
Refer to weather.gov/zlc for more detailed regional
aviation weather and hazard information.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 49 78 50 88 / 0 0 0 10
CTB 46 78 49 87 / 0 0 0 10
HLN 52 80 52 87 / 0 0 0 20
BZN 46 77 46 83 / 0 0 0 10
WYS 39 71 38 75 / 20 20 10 20
DLN 46 75 48 81 / 0 0 0 20
HVR 49 81 51 88 / 0 0 0 0
LWT 46 73 47 79 / 20 10 0 0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls
