903
FXUS65 KBOU 121738
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1138 AM MDT Tue May 12 2026

.KEY MESSAGES...

- Summerlike warmth and drier weather this week, with highs in the
  80s for the lower elevations.

- Warmest temperatures of the week (mid to upper 80s for the
  plains) on Wednesday and Thursday.

- A few afternoon showers and an isolated thunderstorm possible
  from Tuesday through Friday, mainly across the Front Range
  mountains and foothills.

- Elevated fire weather conditions possible for portions of the
  mountain valleys and areas off the Cheyenne Ridge on Thursday.

&&

.DISCUSSION /Through Monday/...
Issued at 223 AM MDT Tue May 12 2026

Current surface observations shows the cold front entering
northern Colorado, and will continue passing through the forecast
area before sunrise. This will lead to slightly `cooler`
temperatures across the region for Tuesday. Forecasted highs will
be in the high 70s. Behind the front, mid-level moisture will be
advected into the region, and with upslope flow a few isolated
showers are possible for the foothills in the afternoon (20-30%
chance). Hi- res guidance shows DCAPE values reaching up to
1500-1600 J/kg, so strong outflow winds associated with any high-
based thunderstorm are possible.

Temperatures will warm back up to the high 80s on Wednesday as the
axis of the mid-level thermal ridge shifts east over Colorado.
Recent ensemble guidance continues to trend warmer with high
temperatures, with GEFS and ECMWF ensembles showing 89F/90F as the
max temperature at KDEN. This is further supported with NBM and
other hi-res guidance indicating the airport reaching 90F. If we
do get our first 90F degree day of the year, it will tie the
current daily temperature record set in 1915. With the passage of
a weak shortwave in the afternoon and lingering moisture with
increasing instability, looks like there are better chances for
scattered convection for the Front Range and adjacent plains into
the early evening.

Above normal temperatures are forecasted to last through the
weekend, although temperatures will be slightly cooler than
Wednesday (but still in the low-to-mid 80s) as the thermal ridge
continues shifting east. Guidance is now in better agreement keeping
the forecast area mostly dry (aside from a few isolated showers for
the Front Range and adjacent plains) as upper level disturbances
trek just north of Colorado. With zonal flow aloft towards the end
of the week, cross-barrier winds could gust up to 40-50 mph at times
in the higher elevations, and 30-40 mph off the Cheyenne Ridge. With
low relative humidity values between 10-15%, elevated to critical
fire weather conditions are possible on Thursday.

A pattern shift is looking likely by the beginning of next week as
models try to resolve an upper level disturbance passing through the
region, bringing measurable precipitation for the forecast area.
There is some uncertainty with the evolution of the shortwave,
however NBM has 20-40% PoPs for Monday, which seems reasonable at
this time.

&&

.AVIATION /18Z TAFS through 18Z Wednesday/...
Issued at 1128 AM MDT Tue May 12 2026

VFR conditions will prevail for all terminals through the TAF
period. Easterly flow persists this afternoon and is set to
continue through mid-evening. Scattered cumulus with bases near
120 will develop 21-22Z today, but a largely capped environment
with limited instability should prevent any outflow concerns for
the most part, although KAPA will be closer to any high-based
activity favoring the Palmer Divide.

This evening, winds are likely to turn to the SE for KDEN/KAPA as
a robust convergence zones sets up, with speeds 14-17 kts possible
through most of the overnight hours. Some uncertainty as to when
this boundary will wash out/push east, with a short window of more
typical S/SW drainage flow possible before lighter and more
variably winds fill in for the morning period.

There`s marginally better instability Wednesday along with
little/no capping, so introduced a PROB30 for KDEN for potential
outflow gusts beginning near 21Z.

&&

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

&&

$$

DISCUSSION...MAI
AVIATION...BRQ