908
FXUS65 KBOU 280919
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
319 AM MDT Tue May 28 2024

.KEY MESSAGES...

- Scattered late afternoon/evening storms today, mainly over the
  Front Range and Palmer Divide.

- Higher afternoon thunderstorm potential on Wednesday, when a few
  severe storms will be possible, mainly for the rural plains.

- Slightly cooler Thursday behind a cold front, with isolated to
  scattered afternoon showers/storms each day through at least
  Saturday.

- Drier/warmer conditions favored as we near early next week, but
  details become more murky Sunday onwards.

&&

.SHORT TERM /Through tonight/...
Issued at 319 AM MDT Tue May 28 2024

Southeasterly low level flow is developing over the plains, with a
broad swirl northeast of Denver producing north winds into the
city. That feature will probably wash out or drop southward as the
day progresses, with winds becoming more easterly in Denver. This
will bring increased low level moisture. Slight warming aloft
means it will still take most of the day to reach the convective
temperature of around 80 at lower elevations. We`ll eventually
have scattered storms mainly over the east slopes of the Front
Range in the afternoon, moving east of the mountains into the
early evening. The storms are most likely to survive over the
higher terrain south of Denver, though an isolated storm or two
over the northeast plains is possible given the increased
moisture. There`s not a lot of shear and CAPEs in the areas we
expect storms will likely be 400-800 J/kg, so gusty winds might be
the main feature of the storms. With light winds aloft, some
clouds will likely linger much of the night and there may also be
some stratus/fog developing in eastern border areas towards
morning.

&&

.LONG TERM /Wednesday through Monday/...
Issued at 319 AM MDT Tue May 28 2024

The ridge axis nudges east on Wednesday as a trough deepens over
the Northern Rockies, and also allows for development of some lee
troughing east of the Front Range. Low-level southeasterly flow
will increase ahead of the approaching front, bringing with it
some modest moisture advection as well as slightly warmer
temperatures, which should climb into the 80`s for most of the
lower elevations. Lapse rates will steepen with the arrival of
colder air aloft, with mixed-layer CAPE in the range of
1,000-1,500 J/Kg looking reasonable for a good portion of our
rural plains. These ingredients should lead to scattered
convection initially developing in the high country near
midday/early afternoon, then pushing eastward into the plains
through the rest of the afternoon and evening. Drier air near the
surface along the urban corridor will likely limit the coverage
and intensity of any afternoon convection, with storms gathering
strength as they move east where both moisture and instability
will be most favorable east of a weak dryline. Potential exists
for some to become severe, especially across the eastern plains,
with wind and hail the primary threat, particularly as they become
better organized.

A cold front will drop south into northeastern Colorado Thursday,
pushing through most of our CWA in the morning, ushering in
modestly cooler temperatures and also tapering the convective
potential somewhat in the afternoon. If it`s a little slower than
anticipated it could provide a boost to afternoon thunderstorm
potential mainly for southern portions of our forecast area in and
around the Palmer Divide. Severe threat should not be as high as
Wednesday`s, however.

By Friday, upper-level flow becomes increasingly zonal as
troughing remains confined well to our north into Canada, and this
remains the case through at least Saturday. Thus, isolated to
scattered afternoon showers and thunderstorms, albeit generally
not of high intensity, appear reasonable for both days. The high
country should see the greater coverage, with precipitation
chances lowering slightly area-wide on Saturday under more
subsident flow and drier near-surface conditions, which will also
result in some modest warming and lower elevations highs
rebounding into the 80`s.

Solutions start to diverge more considerably come Sunday and
Monday with regard to the upper-level pattern. The EC ensemble
suite is on the dry side, keeping predominantly zonal and
subsident flow in place, while GFS ensembles still provide more
opportunity for a shortwave trough and front to sustain at least a
slight chance of some afternoon showers and storms. Overall the
trend seems to be towards the drier solutions however, so our
forecast leans in that direction, along with above-normal
temperatures for the period.

&&

.AVIATION /06Z TAFS through 06Z Wednesday/...
Issued at 1250 AM MDT Tue May 28 2024

VFR through Tuesday. Light winds are expected, except for possible
thunderstorm outflows up to 25 knots after 21z. This is more
likely (40% chance) for KAPA and KBJC with a 20% chance for KDEN.

&&

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

&&

$$

SHORT TERM...Gimmestad
LONG TERM...Rodriguez
AVIATION...Gimmestad