133
FXUS65 KBOU 170954
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
344 AM MDT Wed Jul 17 2024

.KEY MESSAGES...

- Scattered showers and thunderstorms today, with a slight
  uptick in storm intensity and some severe threat.

- Temperatures a few degrees below normal for a change today.

- More typical summer weather through next weekend with scattered
  afternoon showers and storms most days. Temperatures slightly
  above normal Thursday and Friday, then a few degrees below
  normal for the weekend into early next week.

&&

.SHORT TERM /Through Thursday/...
Issued at 353 AM MDT Wed Jul 17 2024

Satellite shows somewhat drier air aloft has moved over the area,
while at the same time the low/mid levels had moistened a bit from
24 hours ago. At the surface, a weak surge was noted pushing
across northeast Colorado in these early morning hours, and is
attempting to support the development of an isolated
shower/storm. The surge/front will also act to enhance the low
level easterly upslope flow and keep moisture advection in place
today.

With plenty of morning sunshine, we expect the airmass to
destabilize sufficiently to bring a round of scattered to numerous
showers and storms this afternoon and early evening. It could be a
fairly early start as well, with convective temperatures (per
forecast soundings) being reached late this morning over the
higher terrain and by noon or shortly thereafter on the adjacent
plains/I-25 Corridor. The models have kept the highest instability
east of the I-25 Corridor, and that`s where CAMs are a bit more
promising regarding strength of storms and a low severe threat.
That said, if the push this morning ends up being a little
stronger then a small threat of a stronger/low end severe storm
would be possible closer to I-25. In any case, the bulk shear
profiles are also marginal, and it appears MLCAPE will be limited
to about 1000-1500 J/kg in the main instability axis - most likely
over the plains.

Overall, we`ll show the highest PoPs in the mountains early to
mid afternoon, shifting to the I-25 Corridor by mid afternoon, and
then the eastern plains late this afternoon and early evening. A
weak disturbance as seen in the QG fields should support a bump in
shower/storm coverage, as well as serving to push a somewhat
organized area of convection east of the I-25 Corridor before 5-6
pm.

Then clearing can be expected tonight with low temperatures near
normal. Highs today will be a few degrees below normal, with mid
and a few upper 80s on the plains, and upper 60s and 70s in the
mountains, foothills, and high valleys.

&&

.LONG TERM /Thursday night through Tuesday/...
Issued at 353 AM MDT Wed Jul 17 2024

On Thursday, the 500 MB high will be centered just west of the Four
Corners with a north-northwesterly flow aloft over the CWA. Models
are showing some drying at lower and mid levels which should result
in a decrease in coverage and intensity of shower and thunderstorm
activity. Most of the storms should be underwhelming with only light
to moderate rain and gusty winds. However, there is the potential
for one or two stronger storms with locally heavy rainfall and
small hail across the plains, mainly east of the Front Range
Urban Corridor during the afternoon and evening hours.

On Friday, we may see a better chance for precipitation across the
forecast area due to a slight increase in moisture combined with a
passing shortwave. Locally rainfall will be possible east of the
divide with the potential for a couple of severe storms with hail,
strong gusty winds and heavy rain possible across the Northeastern
Plains.

Over the weekend into early next week, the upper high amplifies as
it shifts westward over the Intermountain West. This pattern will
place Colorado under the influence of a northerly flow aloft with
upper level shortwaves moving south across the Central Plains
States. This setup should allow a couple of cold fronts to move
across the Northeastern Plains, resulting in cooler and unsettled
weather across the area. At this time, PW`s and instability behind
the surges appear to be somewhat lackluster. Therefore, most of the
precipitation may be showery in nature with limited precipitation
amounts. In this type of pattern, the greatest forcing and moisture
convergence is usually focused from the Continental Divide
eastward across the Southern Foothills and Palmer Divide.
Consequently, some stronger storms with locally heavy rainfall and
small hail will be possible, mainly in these areas.

&&

.AVIATION /06Z TAFS through 06Z Thursday/...
Issued at 1156 PM MDT Tue Jul 16 2024

Main concern will be thunderstorms on Wednesday afternoon and
early evening. Guidance suggests another pretty early start to
convection (around 20Z), and at least scattered coverage. That`s
enough to have TEMPO VRB winds gusting to 35-40 kts and -TSRA in
the forecast...starting at KBJC and KAPA by/shortly before 20Z,
and 21Z at KDEN. Most storms should be out of the area again
before 00Z, with only a small chance thereafter. Outside of the
storms, fairly normal diurnal wind patterns and VFR conditions
will prevail.

&&

.HYDROLOGY...
Issued at 353 AM MDT Wed Jul 17 2024

Model soundings show slightly lower LCLs today resulting in a
slightly deeper warm cloud depth of 2000-2500 ft. Precipitable
water values increase to 1-1.20" for the plains and 0.45 - 0.65"
for the high country. As a result, stronger storms will be capable
of locally heavy rain. Overall, the threat of flooding remains
relatively low as storms should be outflow driven and moving about
20 mph. There will be a limited threat of flash flooding for the
2020 burn scars given the uptick in moisture, as the locally
stronger storms in the high country will be capable of producing a
quick one half to three quarters inch of rain in 30 minutes.
Isolated stronger storms on the plains could produce 1 to 1.5
inches of rain, but most areas will see much less.

&&

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

&&

$$

SHORT TERM...Barjenbruch
LONG TERM...JK
AVIATION...Barjenbruch
HYDROLOGY...Barjenbruch