918
FXUS65 KBOU 150530
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1130 PM MDT Mon Sep 14 2026

.KEY MESSAGES...

- Isolated showers and storms continue overnight.

- 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 /06Z TAFS through 06Z Wednesday/...
Issued at 1130 PM MDT Mon Sep 14 2026

An initial surge of north-northeast winds is currently pushing
southwest across the Denver area TAF sites. Another stronger
frontal surge is still advertised to arrive 08Z-09Z with gusty
north winds to 20-25 kts. Latest models support just enough low
level moisture for areas of stratus developing by daybreak, with
ceilings potentially in the 1500-2200 ft AGL range. While it may
not be widespread, we do have enough confidence for prevailing
MVFR at KDEN ~13Z to 17Z, and a 40% chance it develops by 11Z-12Z.
A little less certainty at KBJC and KAPA so we`ll maintain the
TEMPO there. Dissipation is expected 17Z-18Z, but that also
depends on extent of mid level cloud deck aloft. Otherwise,
easterly flow could keep the stratus deck persisting a couple
hours longer than that. For Tuesday afternoon and evening, VFR
conditions will persist with increasing E-SE winds with gusts to
20-25 kts at KDEN and KAPA. We`ll have a chance of light showers,
but given stability in the low levels we don`t see more than a 20%
chance of winds becoming VRB with those.

Winds will turn S-SW-W 06Z Wednesday and beyond. The threat of any
stratus redevelopment looks quite small (10% chance).

&&

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

&&

$$

DISCUSSION...AA
AVIATION...20

NWS BOU Office Area Forecast Discussion