810 
FXUS65 KBOU 300539
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1139 PM MDT Tue Sep 29 2026

.KEY MESSAGES...

- Rain chances increase overnight into Wednesday afternoon, with 
  the highest rain chances to the south of the urban corridor. 
  Rain will generally be light, but a few localized areas could 
  see brief periods of heavier rainfall. Highest rain amounts are 
  forecast to remain south of our forecast area.
 
- Flood Watch in effect for southern Lincoln and far southeastern
  Elbert counties through Thursday morning. 

- Rain chances decrease late Thursday, leading to warmer and drier
  conditions for the weekend and early next week.

&&

.DISCUSSION /Through Tuesday/...
Issued at 1139 PM MDT Tue Sep 29 2026

Looking at satellite late this evening, the upper level low is 
currently moving out of southern California and into Arizona with
widely scattered showers and storms ahead of the trough to our
south. The showers and storms will gradually move north/northeast
as the surface low tracks northeast. Light showers are starting 
to approach southern Lincoln County as of late this evening. Rain 
chances will increase for the Palmer Divide area late overnight 
through early Wednesday morning and the urban corridor by the 
late morning to early afternoon. Models have continued to trend
lower for rain amounts in our area, due to a more southern track 
of the upper low and eastward track of the surface low. With the 
surface low being a bit more east, it's much harder to get the  
higher moisture to wrap around into our area. We will have enough 
moisture for some lighter rain activity and we are still expecting
rain on Wednesday for many areas south of I-76, but forecast 
amounts have decreased and the risk for flooding has decreased. 

The best chance for higher rain amounts in our area will be in our 
southern most counties (Lincoln and potentially the Palmer Divide), 
but the highest rain amounts for this system are expected to 
remain to the southeast of our forecast area. We've left the 
Flood Watch for the southeastern Elbert and southern Lincoln 
County zone, but there's still uncertainty on if the heavier
rainfall will even make it that far north. Short of some unlikely 
mesoscale feature setting up, like an MCV, we're looking at much 
lower rain totals for our area than previously forecast. Overall 
for our forecast area, expect more of a steady light rain event 
for areas south of I-76 tomorrow, with a slight chance for one or 
two areas to see higher amounts approaching one to two inches.

This system is forecast to move off to the east late Thursday, with 
upper level ridging building in behind it. The ridging should 
hold through the weekend, bringing warmer and drier conditions. 
Highs are forecast to be above normal Friday through Monday, with 
highs approaching the low to mid 80s for portions of the plains by
Monday. Our next chance for rain could accompany an upper level 
shortwave late Monday into Tuesday, but rain chances remain low 
(<30%) for now. 

&&

.AVIATION /00Z TAFS through 00Z Thursday/...
Issued at 1139 PM MDT Tue Sep 29 2026

There is still a good amount of uncertainty regarding ceiling
heights and rainfall placement for the upcoming system on
Wednesday. It appears DEN and BJC will be on the edge of the lower
clouds (2,500–5,000 ft) and rain. Best chance for the lower clouds
at DEN and BJC will be 14-22Z. After 00Z, drier air moves in, but
model cross sections still hold onto a sct-bkn layer around
6000-8000 feet. At APA, rain and lower clouds are expected to move
in between 13Z and 14Z and linger through most of the afternoon.
Improving conditions are expected by 00Z Thursday as well.  As far
as winds go, light southerly winds will transition to the north by
12Z and remain north to northeast through Wednesday.&&

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Thursday morning for COZ047.

&&

$$

DISCUSSION...AP
AVIATION...Meier