281
FXUS65 KBOU 111122
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
522 AM MDT Fri Jul 11 2025

.KEY MESSAGES...

- Scattered afternoon and evening thunderstorms today, producing
  locally heavy rainfall and/or flash flooding.

- Afternoon showers/thunderstorms to continue most days, albeit
  with slightly lesser coverage Sunday and Monday.

&&

.UPDATE...
Issued at 204 AM MDT Fri Jul 11 2025

Scattered thunderstorms will push off the higher terrain and into
the urban corridor and plains mid-afternoon. Model guidance
remains fairly bullish with PWAT forecasts, with upwards of 1"
across the lower elevations through tonight. Modest shear should
keep convection marginally severe at most, however ample moisture
will promote heavy rainfall under thunderstorm cores which will be
capable of localized flash flooding from the lower foothills into
the northeast plains through this evening.

&&

.DISCUSSION /Through Thursday/...
Issued at 242 PM MDT Thu Jul 10 2025

Convection is developing across the CWA this afternoon. Radar and
observations are showing outflow winds from the storms were
gusting up to 65 mph. Earlier this morning, a gust to 70 mph was
recorded at DIA at 1010Z.

Concerning the convection for the rest of this afternoon and
evening, models, including the CAMs, are all indicating scattered
coverage for much of the CWA, but only through this evening; no
later than 02Z.

There will be weak northwesterly flow aloft Friday into Saturday
with a weak upper trough developing just east of Colorado Saturday
mid day. Models continue to show decent CAPE. Progged precipitable
water values continue to be over 1.00 inch for the eastern 2/3rds
of the CWA Friday through Saturday night. The best rainfall
amounts on the QPF grids are progged for late day Friday, less
late day Saturday. Temperatures are below seasonal normals both
Friday and Saturday.

On Sunday, the upper ridge builds in from the west and the
airmass dries out a bit with temperatures getting above seasonal
normals. Pops will be pretty low and confined to the mountains and
higher foothills. The plains look to have poor instability with
low CAPE and a mid level cap in place.

For the later days, Monday through Thursday, the upper ridge is
around on Monday with temperatures to stay above normal.  There is
weak upper troughing Monday evening into Tuesday with a decent cold
front to move down across the CWA. Flat upper ridging is progged
on Wednesday and Thursday with the below normal temperatures to
continue. For pops, Monday is the driest day, with scattered
convection relegated to just the mountains. Late day convection
and precipitation are pretty decent Tuesday through Thursday, with
Wednesday having the highest pops.

&&

.AVIATION /12Z TAFS through 12Z Saturday/...
Issued at 519 AM MDT Fri Jul 11 2025

Light southerly drainage winds early this morning will become
briefly VRB after sunrise before a frontal boundary brings a
shift to NNE/NE winds near 16Z for Denver area terminals. Gusts
20-25 kts will be possible in association with this stalling front
through early afternoon.

By mid-afternoon, developing thunderstorms will begin to push east
off the higher terrain, with greatest chances of terminal impacts
between 22-02Z this afternoon/evening. A period of W/NW outflow
will be possible as any convection approaches, with increasingly
VRB and outflow-driven wind directions likely after 22Z. There`s
notable uncertainty in the duration of convection, which a chance
(~30%) of ISO-SCT -TSRA persisting into the mid to late evening.
Will cover this with a PROB30 for KBJC and KDEN. Some form of
N/NE flow is likely to follow for the overnight period, and lower
CIGS look increasingly likely, particularly after 08-10Z with
bases as low as 010-015.

As for any potential for smoke impacting slant visibility, suspect
diurnal winds will carry enough of a northerly component to limit
such impacts from any wildfires burning in western CO and UT
today.

&&

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

&&

$$

UPDATE...Rodriguez
DISCUSSION...rjk
AVIATION...Rodriguez