199 
FXUS65 KBOU 142054
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
254 PM MDT Mon Sep 14 2026

.KEY MESSAGES...

- Still warm today, with isolated to scattered showers and a 
  couple storms. Mostly light precipitation amounts. 

- Unsettled pattern rest of this week, but plenty of uncertainty
  with regard to daily precipitation chances. Thursday still looks
  like the highest opportunity of measurable rain (50-70%), and a
  locally heavy rainfall threat. 

- Cooler weather arriving for Tuesday. Temperatures bounce back
  Wednesday, but then average around seasonal normals through next
  weekend. 

&&

.DISCUSSION /Through Monday/...
Issued at 251 PM MDT Mon Sep 14 2026

Light showers sprinkled across the area and abundant cloud cover 
have allowed temperatures over the Denver metro and plains to linger 
in just the low 80s. The mountains have seen a bit more sunshine as 
a shortwave continues push east However, daytime heating and 
monsoonal moisture have quickly promoted the development of showers 
and storms over the peaks and ridges with winds occasionally gusting 
to 30-40 mph. Though an isolated shower cannot be ruled out for the 
Denver metro late this afternoon, the best chance of rain at low 
elevations will be over the easternmost Colorado plains, where 
better instability and moisture are in place. 

A cold front will move in from the north late tonight, bringing a 
period of breezy northerly winds in the early morning hours. High-
res model guidance has trended drier with this cold front, limiting 
the development of a persistent stratus layer. However, patchy low 
clouds will likely still develop east of Denver and erode just after 
sunrise. We expect temperatures on Tuesday to stay below normal, 
with highs in the mid 70s at low elevations. Even with precipitable 
water (PW) values in the 90th percentile over much of the state, the 
post-frontal airmass over the plains will struggle to destabilize 
leaving the best chance for showers in the mountains.

A closed upper-level low pressure will begin to slide through the 
Pacific Northwest and Great Basin region on Wednesday, turning flow 
aloft south-southwesterly. Modest monsoonal moisture transport will 
bring PW values as high as 0.80-1.00" to the mountains with higher 
values possible for the eastern Colorado plains, where southerly 
surface winds may advect additional moisture. Therefore, Thursday 
still looks to be the best chance for meaningful rainfall amounts
over the Denver metro. The flash flooding threat appears to be 
localized in nature given the very shallow warm-cloud layer and 
marginal storm motions (LCL-EL mean winds ~18KT).

The evolution of a few shortwave troughs over the Pacific Northwest 
Friday through Sunday remains unclear. However, there will likely be 
enough moisture for daily precipitation chances, particularly over 
the high terrain. Temperatures will remain near-normal or even 
cooler than normal, with highs in the upper 70s and low 80s through 
the weekend.

&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1142 AM MDT Mon Sep 14 2026

Current observations across the TAF sites show some channels of
gusty westerly winds reside east of the Front Range this morning
with some mountain wave enhancement. Meanwhile, the prevailing 
winds are predominantly southwesterly across the TAF sites. Have
made a few changes to this TAF package to account for the more
southwesterly winds hanging on longer than previously forecast,
and added a TEMPO for the next few hours to account for the
westerly gusts occasionally making their way onto the airfields. 
There is low confidence in today's wind forecast as there is 
potential we could end up becoming light and variable, but with
the majority of guidance suggesting we see southwesterly winds
increase by 21/22Z, there is higher confidence in this scenario, 
which is portrayed in the TAF. Have kept the PROB30 for gusty 
outflows with passing showers this afternoon, with instability on 
the marginal side for TS potential have kept the SHRA over TSRA, 
but can't completely rule out a thunderstorm (10-15% chance). 

A cold front is still expected late tonight that will turn winds
to the north by ~6Z at KDEN/KBJC, followed by KAPA about an hour
later. Gusts between 20-25 kts can be expected behind the front,
and hi-res guidance is showing potential for some showers between
7-9Z, with the best chances for KBJC/KAPA, though we may see some
at KDEN too, but confidence is too low to add to the TAF there at
this time. There is also some uncertainty with stratus potential 
with the frontal passage as guidance has trended drier this 
morning, but we could see some low clouds at or around 7,000 feet 
AGL with any showers that develop between that 7-9Z time frame. 

Winds are expected to turn to the southeast by early Tuesday
afternoon, with potential for afternoon showers/thunderstorms near
the TAF sites in the afternoon, once again. 

&&

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

&&

$$

DISCUSSION...AA
AVIATION...9