573
FXUS65 KBOU 271027
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
427 AM MDT Mon May 27 2024

.KEY MESSAGES...

- Mostly dry and mild Memorial Day with light winds. Only an
  isolated late day shower or weak storm over the mountains south
  of I-70.

- Warm through the coming week. There will be limited late day
  thunderstorm activity on Tuesday with better coverage Wednesday
  through Friday. A few severe storms are possible on the plains
  with the highest threat on Wednesday and Thursday.

&&

.SHORT TERM /Through tonight/...
Issued at 407 AM MDT Mon May 27 2024

As a ridge continues to build over the western CONUS, today`s
holiday forecast for northern Colorado looks to be sunshine filled
with light winds and above normal temperatures. There is a slight
chance for some isolated, high-based convection to develop over the
mountains in the afternoon/evening time frame, mainly for areas
south of I-70 where the HREF puts SBCAPE values in the 250 - 500J/kg
range. With dry lower levels, chances for measurable
precipitation are minimal. Forecast daytime temps are high 70s for
the plains with a few locations topping 80, and 60s and 70s for
the mountains and foothills. With clear skies expected overnight,
temperatures are expected to cool off quickly after sunset
resulting in overnight lows dropping a few degrees below normal.
Overall, it will be a beautiful day for a Memorial Day
celebration!

&&

.LONG TERM /Tuesday through Sunday/...
Issued at 407 AM MDT Mon May 27 2024

We`ll settle into a fairly normal early summer weather pattern
this week with convective coverage and the threat of any severe
storms determined by subtle and hard to predict details.

Temperatures will warm Tuesday and Wednesday with light southwest
flow aloft and southeast low level winds over the plains. Moisture
will increase, but it will struggle to get warm enough for
convection on the plains Tuesday. We`ll eventually get some
storms, but they may be focused on the terrain especially in the
afternoon. There could be enough CAPE on the eastern part of the
plains to support strong updrafts, but with questionable heating
and not much shear yet, the severe threat still looks pretty low.

Wednesday will have stronger low level winds and should be warm
enough for a crop of diurnally driven storms. Models have
vacillated on the details of the low level flow, but it still
seems likely that there will be a dryline east of the cities that
could be the focus for a greater severe threat. Mid level winds
are still pretty weak though which will likely limit the threat.
Thursday had looked like a bigger severe threat with stronger
winds aloft and a better chance of advecting moisture westward
ahead of the incoming front. But the timing of the front may be
too fast, or maybe just slow enough for a more substantial Palmer
Divide/east central Colorado severe threat. Both of these days
will see the storm threat mainly along and east of the Front
Range, with less moisture further west but still enough heating
for isolated storms. Guidance temps for these days are similar to
the current forecast and look good.

There`s been a trend in the models since yesterday for a
weaker/more north trough about Friday. We still get a Thursday
afternoon/evening cold front, but in most runs the temperature
drop is limited to 5 to 10 degrees. These "weaker" solutions
could actually be more favorable for thunderstorm coverage and
intensity as there really won`t be much change, still some low
level moisture, enough instability, and maybe sufficient shear for
some threat of severe storms. By Saturday, there`s likely to be
some drying aloft, though how much that reduces the surface
moisture/instability isn`t clear. The severe threat should be
lower, but there could still be a good crop of diurnal storms.
Sunday will have additional drying with some warming and a bit
less shear. However, these changes might be slight, and a return
of southerly winds on the plains could help hang on to some
instability.

&&

.AVIATION /06Z TAFS through 06Z Tuesday/...
Issued at 1143 PM MDT Sun May 26 2024

VFR conditions through the TAF period. Winds are taking slightly
longer to make the turn to southwest than expected, but they are
are still expected to remain a WSW component through the overnight
hours.

Tomorrow will bring northeasterly winds by 14Z - 15Z, and
transition to a more easterly component as peak heating persists
and the diurnal upslope kicks in between 18Z - 0Z. There is a low
probability (10%) that a storm may move south of APA in the
evening.

&&

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

&&

$$

SHORT TERM...Bonner
LONG TERM...Gimmestad
AVIATION...Bonner