555
FXUS65 KBOU 071147
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
547 AM MDT Sun Jul 7 2024

.KEY MESSAGES...

- Cooler temperatures and scattered storms are possible today.
  Some of these storms may produce large hail and gusty winds.

- Lower thunderstorm chances and warmer this week, with near
  record heat by Friday.

&&

.SHORT TERM /Through tonight/...
Issued at 313 AM MDT Sun Jul 7 2024

Stratus clouds have developed across portions of the plains this
morning after a cold front moved trough last night. These clouds
are indicative of the decent moisture that is across the eastern
plains. This moisture is helping to produce 1,000 j/kg of most
unstable CAPE. There is a very slight shortwave trough that is
about to move across our CWA and this trough may produce enough
forcing for a few showers and storms to form this morning mainly
in Washington, Lincoln, and Phillips Counties. How far west the
stratus makes it and when the stratus mixes out are two question
marks in the forecast. The most likely scenario appears to be that
the stratus will push towards the Denver metro around sunrise and
will mix out a couple hours later. This will keep high
temperatures in the 70s across the plains today.

The forecast for this afternoon will be a very tricky one. There
will be northeast winds across the plains with decent moisture as
well as a shortwave trough aloft that will provide QG ascent. The
combination of these factors will likely lead to scattered
coverage of showers and storms mainly over the higher terrain and
I-25 corridor. The challenging part of the forecast will be
predicting the intensity of these storms. Some CAMs forecast most
unstable CAPE values to reach above 1,000 j/kg across the I-25
corridor and eastern plains this afternoon. This, along with ample
deep layer shear around 50 knots, would suggest strong to severe
storms will be possible. The HRRR has had a few runs in a row
where it predicts supercells to form and progress southeastward
across the plains. If this solution were to play out, there may be
a few storms with large hail around 1` in diameter. However, some
other CAMs like the NAM Nest have much less instability with CAPE
values less than 500 j/kg. Those solutions show almost no storms
at all across the plains. In the end, it will come down to the
strength of an inversion that forecast soundings show to be around
600 mb. If the inversion is weaker and more instability builds,
severe hailstorms would indeed be possible. On the other hand, if
the inversion is strong and there is weak instability, there would
be no threat of severe storms today. A solution in the middle
seems like the best bet right now with one or two storms near
severe limits due to hail while most other storms struggle to
intensify on the plains. Forecasts later this morning may have a
better grasp on the severe potential as they will have the benefit
of ACARS soundings and a better understanding of the amount of
stratus clouds.

Across the higher terrain, there will likely be storms along the
Continental Divide and foothills. PoPs are around 60 percent there
this afternoon. While storms will be moving somewhat quickly,
there will be a limited threat of flash flooding on the Cameron
Peak burn area due to training storms.

Tonight, showers and storms will end as the shortwave trough
moves past the area. Low temperatures will be on the cool side as
there could be a few readings in the 40s across the plains.

&&

.LONG TERM /Monday through Saturday/...
Issued at 313 AM MDT Sun Jul 7 2024

On Monday, drier subsident air with a little warming aloft will
move in from the northwest. There may still be some lingering
clouds and light showers exiting our area in the morning, but the
afternoon is looking pretty stable. We`ll keep a chance of some
weak diurnal convection over the Front Range, but that may even
be too much. Tuesday may be similar, as warming offsets further
drying allowing for a little weak convection. There`s also what
looks like a very weak shortwave that could assist a few storms,
all in a pretty marginal environment. In addition, winds aloft
will be pretty light and northerly by then so there won`t be much
motion off the foothills.

From Thursday on, the upper ridge over the west drifts eastward
and we should be nearly dry and hot. There`s little spread in the
guidance temperatures which are all near 100 for Friday through
Sunday, near the records for those dates. It may be completely
dry, though the southeast low level winds and perhaps some mid
level moisture from repeated weak convection in the ridge center
may produce some minimal showers. We trimmed back NBM PoPs a bit
outside of the mountains since steering winds will still be
light.

&&

.AVIATION /12Z TAFS through 12Z Monday/...
Issued at 535 AM MDT Sun Jul 7 2024

Satellite imagery shows stratus developing over the terminals this
morning. DEN is now reporting BKN021 and ceilings should stay
around 2-3 kft until 16-7Z. The stratus will then dissipate and
there will be partly cloudy skies until the mid afternoon. Model
guidance continued to increased the potential for storms this
afternoon so a TEMPO for -TSRA and wind gusts up to 35 knots was
included. There is still some uncertainty whether it will be
unstable enough to generate thunderstorms so it is possible
thunderstorms miss the terminals altogether. Later this evening,
skies will clear and light drainage winds will develop. VFR
conditions are forecast all day tomorrow.

&&

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

&&

$$

SHORT TERM...Danielson
LONG TERM...Gimmestad
AVIATION...Danielson