961
FXUS65 KBOU 151629
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1029 AM MDT Mon Jul 15 2024

.KEY MESSAGES...

- Still hot today, but a few degrees cooler than this weekend.

- Scattered afternoon showers and thunderstorms today with a
  couple severe storms possible over the plains.

- Higher chance of showers and thunderstorms both Tuesday and
  Wednesday, with an uptick in storm intensity and severe threat.
  Temperatures cooling to below normal levels for Wednesday.

- More typical summer weather for the latter half of this week
  with scattered afternoon showers and storms most days.

&&

.UPDATE...
Issued at 1028 AM MDT Mon Jul 15 2024

Overall, minor changes to increase the wind gusts and shift wind
direction this afternoon. Scattered showers and storms will
develop in the mountains early afternoon then should push east
spreading to the foothills and plains. ACARs soundings and METARs
display a few areas approaching 45-55 dew points which should help
with thunderstorms development. PWATs are increasing near
1.00-1.20 inches thus localized brief heavy rainfall could occur
mainly east of I-25 corridor. Model soundings of DCAPE values
between 1000-1200 J/kg could lead to gusty outflow through this
evening. Given multiple CAMs supporting a surge of moisture this
evening near the Colorado / Kansas / Nebraska border, it is
possible the severe threat could continue for counties such as
Logan, Phillips, and Sedgwick until 10 PM MDT.

&&

.SHORT TERM /Through Tonight/...
Issued at 330 AM MDT Mon Jul 15 2024

Overnight low temperatures remain in the low to mid 70s across the
urban corridor this morning, and weak showers remain over the
mountains. These showers are expected to shift eastward over the
plains resulting in a few sprinkles in the coming hours.

Today is expected to be another hot day, but high temperatures
are not expected to be in the running for breaking any records for
the first time in a few days. 500 mb heights will begin to
slightly fall and flow aloft is expected to turn to a more zonal
pattern for today. 700 mb temperatures are looking to be quite a
bit cooler than the previous few days and range from 11C-18C as
opposed to the 21C temps seen the past few days. This will
translate to surface temperatures also decreasing by a few
degrees. Across the plains, high temperatures are expected to be
in the high 90s, and the mountains are forecast to be in the mid
70s to low 80s.

Mid-level moisture is expected to slightly increase again today, and
upslope surface flow will develop this afternoon. This will increase
chances for precipitation. Marginal instability is expected over the
mountains that will be enough to support scattered showers and
thunderstorms this afternoon and evening (~600 J/kg MLCAPE). These
are expected to produce strong and gusty outflow winds, but mainly
light rainfall. Dewpoints in the 60s and modest values of MLCAPE
(~1400 J/kg) are expected across portions of the northeastern
plains. Forecast soundings in these locations also indicate a
shear profile that could allow for a few storms that develop to
become severe. The SPC has the northeastern corner of Colorado in
a slight risk for today with the main threat being severe winds
from outflow-dominant storms.

&&

.LONG TERM /Tuesday through Sunday/...
Issued at 330 AM MDT Mon Jul 15 2024

Tuesday will feature more relief from the recent heat wave, with a
reinforcing cold front arriving. This front is being pushed along
by the upper level trough settling into the Great Lakes region
this week, and actually has some relatively refreshing air behind
it. In fact, by Wednesday temperatures have a high (80-90%)
chance of being below normal across northeast Colorado as cooler
air continues to build in across the Central Plains. At the same
time, moisture levels will be increasing through a combination of
low level moisture advection and continued mid/upper level
moisture trapped under the upper level ridge that is slowly
retrograding toward the Great Basin and Desert Southwest. This
will result in higher coverage of showers and storms each day, and
greater intensity as well given the increase in low level
moisture and dewpoints east of the Rockies rising into the 50s to
lower 60s. MLCAPE rises to 1000-1800 J/kg on the plains east of
Denver Tuesday. SPC has areas roughly along/east of a Fort Morgan
to Limon line in Slight Risk for severe storms - and this looks
good.

For Wednesday, the severe threat should shift farther west toward
the I-25 Urban Corridor where the combination of best heating/low
level moisture advection occurs. Again, MLCAPE should rise into
the 1000-1800 J/kg range and sufficient deep layer shear exists
for a few severe storms. The northeast plains could be more
stable depending on any stratus development and exact amount of
low level cooling.

Overall, there`s not a whole lot of change in the weather pattern
through Thursday and Friday as we stay in north/northwest flow
aloft. An axis of low level moisture and instability would support
scattered thunderstorms, and a daily threat of a couple severe
storms in NNW flow aloft and low level easterly flow. Ensembles
show a return of near normal temperatures (near 90) for the plains
during this period but wouldn`t be surprised if we stay a couple
degrees cooler in this pattern.

There is now more certainty in the ensemble solutions for cooler
weather next weekend, with temperatures several degrees below
normal. Again, the greatest cooling will be over the plains while
mountain areas should stay closer to normal being outside the
influence of upslope flow. The low/mid level moisture profiles
will keep daily chances of showers and storms in the forecast.

&&

.AVIATION /12Z TAFS through 12Z Tuesday/...
Issued at 430 AM MDT Mon Jul 15 2024

Today`s concerns are afternoon convection resulting in gusty
outflows across all TAF sites. Current SSW drainage winds are
expected to transition to a northerly regime between the 15-18Z
time frame. Chances for showers/thunderstorms increase around
20-21Z. Gusty outflows could result in wind gusts reaching 35-45
kts. Convective outflows will likely put a delay on the typical
diurnal flow return time this evening, but SSW winds are expected
once outflows settle down. VFR conditions are expected through the
TAF period.

&&

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

&&

$$

UPDATE...AD
SHORT TERM...Bonner
LONG TERM...Barjenbruch
AVIATION...Bonner