551
FXUS65 KBOU 010327
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
927 PM MDT Sun Jun 30 2024

.KEY MESSAGES...

- Isolated to scattered showers and thunderstorms overnight with
  above normal low temperatures for most fo the forecast area.

- Scattered showers and thunderstorms expected Monday.

- Downward trend in showers and storms beyond Wednesday.

&&

.UPDATE...
Issued at 927 PM MDT Sun Jun 30 2024

There is still some convection going over the CWA with the strongest
storms over southwestern Lincoln County and along the northern
border in Weld County. There is a pretty decent fetch of moisture
and convection upstream to the southwest of the CWA. Several of
the models show plenty of convection to continue off and on all
night, and into Monday morning. Will go with, or keep in, isolated
to scattered pops over the forecast area all night. With plenty
of cloudiness expected, will adjust overnight lows up a tad, at
least over the plains for this update.

&&

.SHORT TERM /Through Monday/...
Issued at 315 PM MDT Sun Jun 30 2024

Radar shows showers and thunderstorms continuing to develop over the
higher terrain this afternoon. A few cells are starting to develop
over the Palmer Divide as well. We are just a degree or two off from
reaching the convective temperature in the Denver metro according to
an ACARS sounding; however, instability is marginal(< 600 J/kg
MLCAPE). MLCAPE values (SPC mesoanalysis) show higher values 500-
1000 J/kg over the plains. Dewpoints haven`t lowered too much from
mixing this afternoon which has kept surface moisture intact. This
will support the showers/storms as they move east off the higher
terrain. For the remainder of the afternoon and evening, expect a
few rounds of scattered showers and thunderstorms. With regard to
strong/severe potential, it is a marginal environment, but
sufficient to support a few strong to severe storms and localized
heavy rainfall and gusts. There`s a boundary set up along the Denver
Cyclone through Elbert/Arapahoe counties which will warrant watching
for storm initiation or weak spin ups.

Tonight, a few high-res models show potential for another batch of
shower/storms to move through late tonight. Given the lacking
agreement, this will be a low chance. Showers push back across the
high country around sunrise Monday. Monday, an upper level jet
positions to the north of the region bringing weak ascent and better
shear. However, instability is fairly marginal (< 600 J/kg CAPE).
This will support scattered showers and storms with a couple
stronger storms possible. With the plume of above normal moisture
nudging into the high country, there is a minor threat flooding
impacts on the burn areas. Enhanced flow should keep them moving;
however, training storms could cause localized impacts from brief
heavy rainfall. High temperatures will likely be in the mid 80s to
low 90s for the lower elevations.

&&

.LONG TERM /Monday night through Sunday/...
Issued at 238 PM MDT Sun Jun 30 2024

Monday night, upper level high pressure will be over the Southern
Plains States with an upper level trough over the Central and
Northern Rockies. This pattern should push the plume of subtropical
moisture to the south and east of the forecast area resulting in
mostly dry conditions east of the mountains. The exception may be
across far Southern Lincoln County where brief heavy rain may be
possible due to lingering high PWAT`s. Precipitation chances may be
higher across the high country due to a westerly orographic flow and
lift from a passing shortwave. Some of these showers and storms
could spread onto the adjacent plains, mainly north of Denver.
However, with the lack of moisture and downsloping flow, only light
rain and gusty winds are expected.

Colorado will be under the influence of a quasi-zonal flow aloft
Tuesday and Wednesday which will allow drier air to move into the
region from the west. Therefore, mostly dry conditions are expected
with possibly a few high based showers and storms with light rain
and gusty winds. On Wednesday, models are showing a return of low
level moisture on the plains with an upper level disturbance moving
across Colorado from the west. As a result, can`t rule out one or
two strong to severe storms across the plains east of Denver during
the afternoon.

On July 4th, a very dry airmass will move into Colorado from the
west in response to a potent shortwave moving across the Northern
Plains States. Consequently, dry weather and clear skies are
expected through the day. Temperatures shouldn`t be too hot with
readings only climbing into the mid and upper 80s across
Northeastern Colorado. The warm temperatures combined with low
relative humidity and gusty northwesterly winds may lead to fire
weather concerns across the the mountains, foothills and adjacent
plains during the afternoon and early evening. Cooler temperatures
(upper 70s to low 80s on the plains) along with a slightly better
chance (10% to 25%) for precipitation are expected on Friday behind
the passage of a cold front.

For next weekend, near normal temperatures along with mostly dry
conditions are expected to continue as a dry westerly flow aloft
remains over the region.

&&

.AVIATION /00Z TAFS through 00Z Tuesday/...
Issued at 655 PM MDT Sun Jun 30 2024

The weak rain showers look to be over for a couple hours at DIA.
Models and upstream satellite pictures point to more showers after
03Z.  Will leave the thunder out for now.  A decent boundary pushed
northward across DIA earlier.  Will leave the southerly winds going
the rest of the evening and overnight.  Speeds should get pretty
light by 05Z. There will be no ceiling issues.

&&

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

&&

$$

UPDATE.......RJK
SHORT TERM...Mensch
LONG TERM....JK
AVIATION.....RJK