FXUS65 KBOU 240545

AFDBOU



Area Forecast Discussion

National Weather Service Denver/Boulder CO

1145 PM MDT Thu Oct 23 2025



.KEY MESSAGES... 



- Mountain snow showers become more numerous this afternoon and

  evening, and isolated rumbles of thunder also possible. Slick

  travel over high mountain passes, mainly in the mountains around

  Summit County tonight including I-70.

 

- Scattered light rain showers tonight on the plains, mainly south

  of I-70.



- Potential for an impactful system late Sunday into Monday of 

  next week. Most likely impacts will be strong winds and mountain

  snowfall.



&&



.DISCUSSION /Through Thursday/...

Issued at 241 PM MDT Thu Oct 23 2025



An upper level low will track from the Four Corners east across

the southern Colorado border through Friday. This will bring

several rounds of showers to the southern half of the state as it

moves through, but northern Colorado will be on the edge of the

area with lift and instability. Our main feature will be the

shower band now over central and south central Colorado as it

lifts north and rotates around the low. This should bring a decent

round of showers to areas from Winter Park and Summit county

southward in the late afternoon and evening, then the focus of

this should shift north and westward, bringing some light showers

with some accumulation to areas further north. Lighter showers

will likely persist in the central mountains and over the ridges

after this feature is done, but there shouldn't be much more

accumulation. It's still warm and there's not much temperature

advection, so most of the accumulation should be above 10,000

feet.



For the plains, the east end of that shower band should rotate

through Denver between 7 and 10 PM. There could be some rain

reaching the ground, but probably not more than a few hundredths.

Further east a deeper dry layer and less cooling aloft will mark

the east edge of the showers.



On Friday, the showers on the back edge of the system should be 

dragging across the plains south of I-70, while lingering mountain

showers diminish. There may still be some minor instability to 

keep some very light showers going over the mountains into the 

afternoon, but the accumulation should be done. While the showers 

will likely stay to the south, Denver will probably be under the 

cloud shield of this system all day, and between that and about 10

degrees of cooling, it will feel like a fall day. There will 

likely be some clearing along the northern border in the 

afternoon.



Saturday should be one of the nicer days of the week, with

temperatures in the upper 60s and light winds as we sit in between

storm systems.



A broad trough is expected to push eastward Sunday into next week,

with west-northwesterly flow aloft quickly strengthening over the

region. At least one fairly good push of moisture is expected to

reach the mountains by late Sunday afternoon, leading to

orographic snow showers most of Sunday night into Monday. The

ECMWF ensemble is a little wetter across our northern mountains

than the GEFS, but both would suggest light to moderate snowfall

totals, mainly over the Park Range. Across the plains, the

continued WNWerly flow will limit precipitation potential and most

ensemble members have zero QPF. 



The bigger impacts across the lower elevations will be

increasingly gusty winds as the mid-level flow strengthens.

Guidance isn't particularly sold on where the strongest 700mb

winds are (not a surprise for a Day 5-6 forecast) but there's good

confidence in a brief period of cool/breezy conditions early next

week.



Guidance favors a return towards a warmer/drier pattern by the

middle of the week, with broad support from most ensemble members

across the 12z suite.



&&



.AVIATION /06Z TAFS through 06Z Saturday/...

Issued at 1134 PM MDT Thu Oct 23 2025VFR conditions expected throughout the TAF period. A weak boundary

has moved through the terminals shifting winds to the northwest.

The northwest winds should continue for the majority of the night

but the direction may shift towards west or southwest towards

sunrise. A light northerly or northeasterly wind will develop and

persist throughout the day tomorrow. 



Some high resolution models indicate very light rain showers over

the terminals during the day on Friday. These will not be enough

to impact operations. 



&&



.BOU WATCHES/WARNINGS/ADVISORIES...

None.



&&



$$



DISCUSSION...Gimmestad/Hiris

AVIATION...Danielson