584
FXUS65 KBOU 010526
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1126 PM MDT Sun May 31 2026

.KEY MESSAGES...

- A chance for strong and severe thunderstorms returns for Monday
  and Tuesday afternoons, with locally heavy rain possible.

- Trending warmer and drier by the end of the week.

&&

.UPDATE...
Issued at 804 PM MDT Sun May 31 2026

Quick little update for isolated showers that have developed
in/near the Front Range. There was just enough late day heating
and instability per ACARS soundings and mid level moisture per
satellite for isolated light rain showers. Those may very well
continue into the evening, with the chance spreading onto the
northeast plains overnight into Monday morning. An isolated storm
or two will also be possible over the northeast plains with slight
mid level instability. The severe weather threat on Monday will
hinge on how far south/strong the morning frontal push is, and
how much the airmass can recover for the afternoon. At this time,
appears the Palmer Divide and adjacent plains into east Central
Colorado would be the most prone.

&&

.DISCUSSION /Through Sunday/...
Issued at 247 PM MDT Sun May 31 2026

It is a sunny afternoon for most of Colorado today, with near-
seasonable temperatures ranging from the low 60s over the mountains
to the low 80s at low elevations. Satellite imagery shows increasing
cloud cover over the high terrain, but most areas should remain dry
with only a small chance (15%) for a light shower over the highest
mountain peaks and western slopes.

The latest SPC convective outlook for tomorrow has placed a slight
(2/5 level) risk over the NE Colorado plains extending west into
Weld County and DIA, and a marginal (1/5 level) risk over the
foothills. East to southeast flow at the low levels will advect
dewpoints in the 40s-50s into the east Colorado plains and Denver
metro area by the early afternoon hours. High-res ensemble guidance
suggests precipitable water (PW) values in the 90th percentile of
climatology will be in place Monday afternoon through Tuesday
evening, with values over the easternmost counties of our CWA
exceeding 1.0 in. PW values at times. A decent amount of shear (40-
50 kt bulk shear), curved hodographs, 0-3km SRH ~100 m^2/s^2, and
upslope enhancement will provide an environment that will be
conducive to a few strong supercells that will be able to produce
large hail and strong winds. From a thermodynamic perspective,
CAPE will extend vertically into the hail growth zone, and steep
mid- level lapse rates >7.0 C/km will also be present. There is
also a small (30% chance) probability that showers and
thunderstorms could linger into the late evening or early morning
hours of Tuesday, aided by strong low-level moisture advection.

The convective environment for Tuesday afternoon will be very
similar to Monday`s setup. The primary difference in Tuesday`s setup
will be weaker shear, which will limit the potential for a more
discrete storm mode. Monday evening`s convection will also pose
additional challenges for convective initiation on Tuesday given the
increased chance for low stratus or fog in the morning, and a more
capped environment to begin with. However, high-res model guidance
suggests CAPE values exceeding 1500-2000 J/kg and 700-500mb lapse
rates greater than 8.5 C/km, which would support another afternoon
of severe hail potential if any CIN is overcome.

Looking ahead, daily chances for afternoon showers and weak
thunderstorms will persist through next Sunday. Upper level flow
remains weak and there is no strong signal for synoptic forcing.
Long-range ensembles suggest ridging setting up over the central
U.S. Plains by Tuesday afternoon, and a return to zonal flow to
start the weekend. Temperatures will generally trend above normal,
with 90-degree afternoon highs becoming increasingly likely for
Saturday and Sunday over the Denver area.

&&

.AVIATION /06Z TAFS through 06Z Tuesday/...
Issued at 1119 PM MDT Sun May 31 2026

Latest data suggest a few sprinkles or virga will be possible
overnight with ceilings staying around 10000 ft thru 10z. For
now, don`t expect any microburst activity.  Winds will be light
and variable but become easterly around 12z as a weak cool front
moves across. By early Mon aftn, sfc winds will be mainly ESE with
a chc of tstms between 20z and 00z. At this time, activity looks
to be fairly sct so have maintained a prob30. There is a 10
percent chance of a stronger tstm affecting DIA as well. Ceilings
in the aftn will be around 10000 ft but may briefly drop to 6000
ft if a tstm moves across.  In addition, gusty outflow winds may
produce brieg gusts up to 40 mhp.

After 00Z tstm chances will decrease but can`t rule out a slight
chc of -shra. Winds will become more SE by early Mon evening.

&&

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

&&

$$

UPDATE...20
DISCUSSION...AA
AVIATION...RPK

NWS BOU Office Area Forecast Discussion