615
FXUS65 KBOU 010000
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
600 PM MDT Sat May 31 2025

.KEY MESSAGES.

- Scattered afternoon showers and thunderstorms continue through
  Sunday (mainly over the higher terrain).

- Warmer weather makes a return through the weekend, with highs
  back into the low 80s for most of the plains.

- Wetter pattern returns early next week (Mon-Wed), along with a
  return to below normal temperatures. Snowmelt plus rainfall will
  lead to high flows on mountain streams.

&&

.DISCUSSION /Through Saturday/...
Issued at 251 PM MDT Sat May 31 2025

Weak convection has begun over the mountains and should increase
through the late afternoon. There`s still potential for a few
cells to move southeast off the mountains, though the environment
at lower elevations is less favorable than yesterday. The current
forecast seems to have a decent handle on this, though we did
increase the cloud cover overnight for lingering mid level clouds.
Sunday`s environment isn`t much different, although a Denver
cyclone boundary could help get a bit more storm activity going
south of Denver in the mid to late afternoon. Temperatures will be
4 to 8 degrees warmer. Denver will likely be near 90, but probably
just short of that mark.

The model handling of the Monday/Tuesday system is not that bad,
though the resultant QPF still varies. One model trend is to move
the synoptic scale lift steadily eastward and bring an end to the
significant precipitation earlier on Thursday. Some model runs had
slowed the departure over the plains resulting in larger rain
amounts. Now the consensus is that the rain in the mountains will
mostly be Monday afternoon and Monday night, and on the plains 4
to 6 hours later. This reduces the forecast rain amounts a bit.
Most models are still in the 0.5 to 1.5 inch range for the
mountains, and 0.75 to 2 inches for the plains. The NBM is in the
middle of these ranges overall and seems adequate. There are some
runs with lighter amounts, and a few outliers that have twice
that. It seems unrealistic to have that much over a large area,
but there is potential for embedded thunderstorms or a mesoscale
focus that lasts a few hours. The most likely chance for intense
rain would be with convection Monday afternoon and evening. See
below for hydro impacts.

There`s pretty good agreement on keeping a cool moist environment
with another shortwave late Wednesday. Amounts should be much
lighter overall, but PoPs will still be high and there could be
some localized heavy showers. There`s a drying and warming trend
after that, with Thursday as the transition day. NBM guidance is
on the warm edge of the envelope, but this is probably OK, with
temperatures back around 80 in Denver Friday and Saturday. With
drying aloft but probably less and the surface, this looks like a
fairly typical June pattern and there could be some threat of all
kinds of severe weather and burn area flooding by the end of the
week, though there`s nothing that looks like a particular threat.
Just a fairly normal early June pattern.

&&

.AVIATION /00Z TAFS through 00Z Monday/...
Issued at 541 PM MDT Sat May 31 2025

VFR conditions expected through the TAF period. Light winds will
turn drainage by 05/06Z and then turn more W/NW mid-morning.
Chances for thunderstorms increase by 21Z (more 22Z/23Z for DIA
and APA) with the possibility of strong VRB outflows gusting up
to 35 kts at times. There is a chance that storms could stay north
and south of DIA tomorrow, but even then gusty outflows remain
possible. Storms will move out of the area around 01Z/02Z and
winds should return to drainage.

&&

.HYDROLOGY...
Issued at 251 PM MDT Sat May 31 2025

Forecast temperatures, snowmelt, and rainfall will be enough to
cause rises on streams in the mountains, and minor flooding could
result late Monday and Tuesday in areas that get heavier
rainfall. In areas east of the mountains and burn areas, the
threat is lower, but there could be enough rainfall to cause
localized minor flooding.

Larger rivers should be able to handle the most likely rain and
snowmelt, though they will be running high. There is a small
chance of rain that is heavier than expected on a scale of a
county or two, that could produce flooding on one of the larger
rivers. At this time, this appears to be a low probability (10
percent or less).

&&

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

&&

$$

DISCUSSION...Gimmestad
AVIATION...Ideker
HYDROLOGY...Gimmestad