Keystone

000
FXUS65 KBOU 301739
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1139 AM MDT Fri Oct 30 2026

.KEY MESSAGES...

- Mild and mostly dry to end the week.

- Unsettled weather returns late this weekend and early next week.
  Mountain snow is likely (>70% chance) above 8500ft during this
  time. High uncertainty remains for the foothills and plains. 

&&

.DISCUSSION /Through Thursday/...
Issued at 1026 PM MDT Thu Oct 29 2026

For late tonight thru Fri morning main concern is how widespread 
dense fog may become along portions of the I-25 Corridor from 
Denver north to the Wyoming border and points eastward. HRRR has 
been consistent in showing fog developing over ern Larimer and 
Weld county by midnight and then spreading it southward into nrn 
portions of the Denver area by 3 am or 4 am. This fog would then 
linger thru the mid morning hours on Fri before lifting. In 
addition, soundings show some potential for drizzle as well.

Meanwhile, for the rest of Fri, the flow aloft will be SW with 
only isold showers possible in the mtns and far nern plains in the
aftn. As for highs, readings will be in the lower to mid 60's 
across the plains, however, lingering low clouds could keep temps 
in the 50's over the far nern plains.

For Sat, little change is expected as SW flow aloft remains over the 
area. There still appears to be a weak disturbance embedded in 
the flow which may bring a chc of showers to portions of the 
higher terrain with an isold shower threat across the plains. 
Temperatures will remain in the upper 50's to mid 60's over nern 
CO.

Looking ahead to Sun and Sun night, there continues to be some 
uncertainty as to how an upper level trough along the West Coast 
evolves.  The ECMWF and GFS now have a disorganized elongated upper 
level trough moving into the nrn Rockies and Great Basin by Sun 
night.  Ahead of this feature, there will be quite a bit of 
subtropical moisture affecting the higher terrain, especially by Sun 
night.  As a result, should see an increasing chc of showers over 
the higher terrain with snow levels dropping below 10000 ft late Sun 
night.  Across the plains, it looks dry and windy thru Sun aftn as 
sfc low pres intensifies from ern WY into ern CO.  By Sun night, 
latest data shows varying precip chances across the plains. 
For now, have kept in a chc of showers as a band of mid level QG 
ascent moves across overnight.

On Mon, the ECMWF and GFS have two main areas of energy associated 
with the elongated upper level trough.  One piece stays over the nrn 
Rockies while a 2nd piece of energy moves across srn CO/nrn NM.  If 
this occurs best chc of decent precip would stay mainly to the north 
and south of the area.  Meanwhile, both models shows a stg cold 
front moving across the plains with gusty north winds behind it. 
  
For Mon night into Tue, the ECMWF and GFS keep the two pieces of 
energy separated as the one piece over the nrn Rockies moves SSE 
across Colorado while the other piece of energy moves from nern NM 
into central Oklahoma. In addition, the GFS intensifies the upper
level low as it moves into Oklahoma by late Mon night. The ECMWF 
has very little additional precip Mon night into Tue as much drier
air spreads across the area. Meanwhile, the GFS has a band of 
precip over the ern plains Mon night but also decreases the chc of
precip over the area on Tue. Winds will remain gusty over the 
plains Mon night into early Tue as well.
  
By Wed an upper level ridge will build over the area ahead of 
another possible system moving across on Thu. For now, Wed looks 
dry and warmer ahead of the next system.

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1126 AM MDT Fri Oct 30 2026

Fog has moved out of the TAF sites, leaving VFR conditions through
this evening. Winds will be light from the east/northeast this
afternoon, becoming light and variable this evening, and turning
towards drainage overnight. Models have another circulation
forming to the north and east of DEN, turning winds northerly or
variable at the TAF sites around 12Z. Fog is forecast to develop 
again in the early morning, approaching BJC and DEN around 10Z or 
11Z, potentially moving over the airports between 12Z and 16Z. We 
have a tempo for LIFR conditions during that time window at DEN
and BJC. Fog will start to clear between 16Z and 18Z. Once again,
fog is expected to stay just to the north of APA.

&&

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

&&

$$

DISCUSSION...RPK
AVIATION...AP