512
FXUS65 KBOU 221908
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
108 PM MDT Fri May 22 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms through this evening, mainly
  south of I-70. Remaining cool.

- Warmer and drier this weekend, with only isolated showers and
  storms possible each afternoon/early evening.

- Remaining mild next week, but scattered afternoon and evening
  showers and storms expected most days.

&&

.DISCUSSION /Through Friday/...
Issued at 108 PM MDT Fri May 22 2026

Satellite imagery shows a shortwave moving through eastern Utah
and western Colorado, with weak QG lift arriving during peak
heating. This will support another round of showers and a few
thunderstorms across portions of our forecast area - strongly
favoring the Palmer Divide. That area will be under the influence
of favorable frontogenesis and a right entrance region of a weak
upper level jet well into this evening. Therefore, this batch of
showers and isolated weak storms (MLCAPE less than 300 J/kg)
should be rather persistent. Denver will likely be on the edge of
the showers, with the southern/western portions seeing more rain
while the chances of anything appreciable diminish into the
northern suburbs and points north to Fort Collins. Rain showers
will eventually push east of the I-25 Corridor by midnight and
then gradually diminish/end overnight over the adjacent plains of
the Palmer Divide.

Ridging will occur this weekend with warmer temperatures and
drier conditions. However, there is still enough moisture to
support development of a couple higher based showers and storms
over the mountains and Palmer Divide/Cheyenne Ridge area in the
afternoon. Also, enough low level convergence along the developing
lee trough Saturday could support a couple storms over the
eastern plains. Highs are expected to warm from the lower to mid
70s on the plains Saturday, into the lower to mid 80s by Sunday.

The upper level ridge is still forecast to push east of the
forecast area on Monday as upper level low moves into southern
California. This will support a gradual increase in precipitable
water, and thus convective development will likely turn up a
notch. By Tuesday, further moisture advection occurs in deeper and
stronger southerly flow, and there`s even a hint of weak negative
tilt from an ejecting shortwave. This will support increasing
storm chances, as well as the threat of a few strong/severe
storms.

From there, ensembles support a blocking ridge developing from the
upper Midwest/western Great Lakes into southern Canada. While
details vary considerably between runs at this point, it appears
we`ll still be mostly in southerly flow or have sufficient
moisture around to support scattered and daily afternoon showers
and storms through much of next week. Temperatures should average
slightly above normal.

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1231 PM MDT Fri May 22 2026

Current winds are generally light and variable, with some N-NE winds
starting to arrive at KDEN. Winds will continue to turn clockwise
this afternoon, with light easterlies by 00Z. However, strong
southerly winds will take over by around 02Z due to an outflow
originating over the Palmer Divide, near KAPA.

KAPA will see the best chance for an isolated thunderstorm early
this evening between 00-03Z, in addition to a 30% chance for showers
through 06Z. KBJC and KDEN will have a lower probability of seeing
showers over the terminals, but we opted to introduce a PROB30 for
KDEN between 02-04Z given that current observations show a moister
environment than previously depicted by high-res model guidance.
Winds late tonight will remain mostly S-SSW before a shift to more
westerly winds tomorrow morning.

High-based showers will begin to develop over the foothills around
19-21Z Saturday afternoon, bringing the potential for variable gusty
outflows and microbursts.

&&

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

&&

$$

DISCUSSION...20
AVIATION...AA

NWS BOU Office Area Forecast Discussion