106 
FXUS65 KBOU 031800
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1200 PM MDT Fri Oct 3 2025

.KEY MESSAGES... 
 
- Well above average and near record warm temperatures today.

- Becoming windy most locations Saturday with elevated fire
  weather conditions. 

- Showers and a few storms enter the picture Saturday and Saturday
  night, with potential for a few strong to severe storms over 
  the northeastern plains. A new dusting of snow likely (70% 
  chance) for the mountains. 

- Cooler for the end of the weekend into early next week... but
  warmer temperatures likely to return by mid/late week.

&&

.DISCUSSION /Through Thursday/...
Issued at 222 PM MDT Thu Oct 2 2025

Another mild and dry day is expected across the forecast area today 
under upper-level ridging. Satellite imagery shows mostly clear 
skies stretching from the Desert Southwest all the way to western
Minnesota. Upstream, a shortwave trough is seen entering the 
Western CONUS, with an upper-level closed low visible, spinning 
just off the coast of the Pacific Northwest. The combination of 
subsidence, solar heating, and 700 mb temperatures ranging between
9C to 15C across the forecast area, we are expecting afternoon 
high temperatures to be about 10-15F above normal today, with 
widespread 80s expected across the lower elevations, 70s for the 
foothills and mountain valleys. Overnight lows will be similar to
last night's. 

Despite still showing some small discrepancies, ensembles largely
agree that the upper-level trough will move eastward across the 
Great Basin on Friday. Ahead of its arrival, we are expecting 
another dry day with above normal afternoon high temperatures 
across the forecast area. 700 mb temps will warm a few degrees 
under increasing southwesterly flow aloft, warming afternoon high 
temps a few degrees over today's. This will bring us near record 
high temps across the plains (KDEN hit 88F on this day in 2005). 
We should see mostly clear skies continue through early afternoon 
when moisture will start to increase from west to east. The 
increasing southwesterly flow aloft mixed with lee troughing east 
of the Rockies will result in breezy conditions in our mountain 
valleys and across portions of the plains, where 35-45 mph gusts 
will be possible through the afternoon. Can't rule out some 
scattered afternoon showers or weak storms developing in the 
afternoon, mainly for the northern mountains. Could even see some 
light snow over the highest elevations overnight. 

Saturday will be an active day as the trough passes across
Colorado. QG forcings reach their max in the afternoon as a near
70 kt 500mb jet moves over the Rockies. Showers and a few storms 
will move across the higher elevations first before making their 
way onto the lower elevations as the day progresses. At the 
surface, southerly winds will increase, with gusts between 35-45 
mph possible across the eastern plains and mountain valleys. Bulk 
shear values approaching 50 kts will be possible across portions 
of the northern plains where afternoon temps are forecast to be in
the mid 80s. We can't rule out the threat for a few severe storms
developing in the late afternoon/early evening, mainly for the 
northern plains, where a cold front is expected to move into 
northern Colorado, and the SPC has put us in a Marginal Risk. 

Much cooler temps and lighter winds are expected on Sunday behind
the cold front. Afternoon highs will struggle to make it into the
70s across the plains. We will see southwesterly flow aloft 
diminish as the jet moves across the Northern Plains with the
exiting trough. There will be enough residual moisture in place
for some afternoon showers to develop, with temperatures cool
enough to drop snow levels to near 10,000 ft for the northern
mountains, where we may see an inch or two accumulate at our
highest elevations overnight. 

Ensembles still show some discrepancies with regards to our next
trough expected to drop into the Great Basin, but it's looking
like cooler temperatures will stick around through the beginning
of next week, with precipitation chances each afternoon before a
warming and drying trend returns by midweek. 

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1159 AM MDT Fri Oct 3 2025

Main concern will be the winds. Southwest winds prevail over the
southern metro area to start this period, with KDEN being right on
the edge of the shear zone that is expected to become more
defined this afternoon. This boundary will be characterized by 
south/southwest winds to the south, and easterly winds north of 
it. There is a 30-40% chance the boundary could move onto the KDEN
field, but most likely a more easterly wind would develop and 
persist through 01Z. KBJC will be north of it, while KAPA should 
main reside to the south of the aforementioned boundary. After 
01Z, it appears normal S/SW winds will develop and persist through
14Z.

By 15-16Z, south/southwest winds will start to increase as
gradients tighten, with further increase expected through the day
with stronger mixing. Gusts to 28-34 kts will be possible by 20Z,
and any passing showers/virga could result in isolated stronger
gusts to ~40 kts considering the mean flow. It should also be 
noted there's a 20-30% chance that the backdoor cold front sneaks 
into KDEN and KBJC at some point Saturday.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Bonner
AVIATION...Barjenbruch