209
FXUS65 KBOU 180224
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
824 PM MDT Wed Sep 17 2025

.KEY MESSAGES...

- Fewer and less intense showers and storms through this evening,
  decreasing overnight.

- Drier weather Thursday onward, with warmer temperatures
  beginning Friday.

&&

.UPDATE...
Issued at 801 PM MDT Wed Sep 17 2025

The forecast remains largely on track this evening, with only
minor adjustments made to the PoPs. Have trimmed them slightly
across parts of the plains, particularly south of the Cheyenne
Ridge, where persistent northerly winds are expected to limit
precipitation potential.

Despite the upper-level low remaining over the region, we are
already observing increasing atmospheric stability, which should
further suppress convective development overnight.

&&

.DISCUSSION /Through Wednesday/...
Issued at 259 PM MDT Wed Sep 17 2025

The upper low over southeast Wyoming will be drifting southeast
overnight. There`s a pocket of cooler air aloft and a bit of QG
lift that will come along with it. We had been favoring the
southern part of our area for better instability and higher PoPs
overnight, but the situation is more complicated than that. The
surface will likely wind up warmer in the south, and showers that
form over the relatively warm Front Range and central mountains
will drift that way. But the cooling aloft will be better in the
north along with the moisture and lift. So we`re bumping up PoPs a
bit in the north and dropping them a bit in the south. CAPEs are
lower today, around 400-600 J/kg so enough for some thunder but we
shouldn`t have anything strong. Weak lift persists much of the
night, so we may just see a gradual fade in the shower activity.

Thursday morning drier and warmer air aloft will be moving over,
but there will still be some cool moist air at low levels. There
will likely still be some stratus over the plains that will take
a while to break up. It`s not clear if Denver will still have
cloud cover or if it will be drifting east by morning, but we`ll
likely have plenty of sun in the city much of the day. There may
still be enough moisture for some weak mountain convection in the
afternoon, but the drying will be continuing.

The models are trending less amplified with the upstream ridge
over the weekend, bring a vigorous shortwave that may have a
closed low embedded in it down into the plains early next week.
While there`s an upward trend in the dynamic strength of this
system and it may be near to us, it`s in a relatively dry and
stable environment. The NBM hasn`t really responded to this trend
yet, keeping PoPs low with only a little cooling in the
Monday/Tuesday time frame. We`ll have to keep an eye on the
possible need for a greater impact, but given the surroundings it
still probably won`t be much. It still looks like there will be a
high amplitude ridge west of us by the middle of next week, so
we`ll likely continue to have dry weather and seasonal
temperatures.

&&

.AVIATION /00Z TAFS through 00Z Friday/...
Issued at 533 PM MDT Wed Sep 17 2025

Currently, some weaker thunderstorms are present to the west and
south of the Denver area TAF sites. Some light rain showers are
also present across the TAF sites. The main concerns for this TAF
period will be for CIGs to drop to MVFR conditions, and the
potential for a brief weak thunderstorm to make its way across the
TAF sites (KAPA has the best chance). However, it`s still looking
like showers are the most likely scenario as instability is still
lacking across the area, and storms continue to weaken as they
move off the higher terrain. Showers should diminish by late
tonight, with lower CIGs remaining through the early morning.
There is potential for CIGs to linger slightly longer than what is
in the TAF as some of the more moisture aggressive models show
the low-level moisture taking a little longer to push eastward,
but the drier solutions have them scattering out between 9-11Z.

Tomorrow is expected to be a typical diurnal wind pattern day,
with light and VRB winds in the morning, giving way to NE, to E
winds for the afternoon. VFR conditions are expected to remain in
place once the morning CIGs scatter out, with no precipitation
expected.

&&

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

&&

$$

UPDATE...Bonner
DISCUSSION...Gimmestad
AVIATION...Bonner

NWS BOU Office Area Forecast Discussion