070
FXUS65 KBOU 281715
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1115 AM MDT Thu Aug 28 2025

.KEY MESSAGES...

- Scattered to numerous storms through Saturday with locally heavy
  rainfall in a few areas.

- Warmer and drier Sunday through early next week.

&&

.UPDATE...
Issued at 304 AM MDT Thu Aug 28 2025

Low stratus and fog remain fairly widespread across the far
eastern plains... though we`ve yet to see that spread into the
I-25 corridor so far. Unlike the last couple of nights, short term
guidance keeps most of the thicker stratus/dense fog east of the
metro, and this seems reasonable given the light drainage winds
that have persisted across the area in the last couple of hours.
Models do eventually have northeast winds develop during the
morning, but I suspect we`ll be off to a sunnier start compared to
the last couple days.

Meanwhile, afternoon convection is expected yet again this
afternoon, as above normal moisture remains over the region. We`ll
lose some of the upper jet support, and thus there`s better
chances for rain will be across the higher terrain. Still about a
50/50 shot of seeing measurable rain across most of the metro, but
there will still be widely scattered showers/storms by the
mid/late afternoon. Friday looks relatively similar with another
round of showers/storms across the forecast area.

We`ll start to lose some of the better moisture as we get into the
weekend, but guidance does have an 80kt upper jet streak sinking
southward across the CWA between Friday night and Saturday
evening. There may be some sort of weak frontal push in that time
period as well, though there`s quite a bit of spread across the
various 00z deterministic models.

Beyond the weekend the pattern looks quite a bit drier, but
temperatures still look like they`ll hold at near or below normal
values as we get into next week.

&&

.DISCUSSION /Through Wednesday/...
Issued at 225 PM MDT Wed Aug 27 2025

Scattered thunderstorms, some with very heavy rain, have developed
early this afternoon and trend should continue through the rest of
the afternoon. We have now warmed sufficiently to greatly weaken
or eliminate the cap, so we are primed for convection in the lower
elevations. Storms will be intense, with high precipitable water
and MLCAPE around 1000 J/kg and sufficient shear to keep updrafts
in tact, heavy rain is becoming more likely. See the Hydrology
portion of this forecast discussion for more details. Storm
coverage should also be greater considering synoptic scale lift
(at least along/north of I-70) in the left exit region of the
upper level jet. Thus, one if not two batches of showers and
thunderstorms can be expected from this afternoon into this
evening, with the storms likely organizing further as they push
E/SE across the plains this evening. A few showers may linger
overnight with brief light rain or sprinkles.

Thursday should feature similar conditions to today, although the
upper level jet shifts northward, and puts us in weak subsidence.
Thus, coverage should decrease and there may be a slightly
stronger cap to overcome. However, storm intensity should remain
with just as much MLCAPE and shear.

Models are consistent with slight drying starting Friday and
lasting into Saturday. This occurs as flow aloft transitions to
more westerly Friday and then northwesterly Saturday. While storm
coverage and intensity should gradually decrease, there is
potential for an embedded disturbance on Saturday which could
bring a brief uptick in coverage again.

Sunday is almost certainly shaping up drier (80% confidence) per
ensemble output, and thus much lower chances of precipitation.
Temperatures will then warm through Monday and Tuesday with highs
averaging around the mid 80s in lower elevations. While it`s
early, there are some models showing a taste of fall reaching the
Central and Northern Plains toward the middle of next week.

&&

.AVIATION /18Z TAFS through 18Z Friday/...
Issued at 1109 AM MDT Thu Aug 28 2025

Thunderstorm coverage this afternoon will be more widely
scattered than past few days, thus have kept in a prob30 for
tstms between 21z and 01z. Winds will gradually become light
northeast in the next few hours and then will become more erratic
in direction as outflow boundaries move across by late aftn. By
this evening winds will become SE and then more southerly by 06z.

&&

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

&&

$$

UPDATE...Hiris
DISCUSSION...Barjenbruch
AVIATION...RPK

NWS BOU Office Area Forecast Discussion