023
FXUS65 KBOU 152329
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
529 PM MDT Thu Aug 15 2024

.KEY MESSAGES...

- Isolated to scattered showers and a couple storms tonight

- Hotter and drier Friday and Saturday

- Precipitation chances increase beginning Sunday, with some
  moderation in temperatures, though still warm.

- There will be a limited or greater threat of flash flooding over
  the burn areas Sunday through the middle of next week.

&&

.SHORT TERM /Through Friday/...
Issued at 250 PM MDT Thu Aug 15 2024

Satellite shows a fair amount of cumulus growing over the
mountains and higher terrain, with a notable pocket of slight
cooling and subsequent delay of hitting the convective
temperature behind the patch of clouds that moved across this
morning into early afternoon. Those clouds have pretty much burned
off, so we`re back to typical diurnal buildups. However, moisture
levels are decreased from the last several days and instability
is quite weak with only a couple hundred J/kg. Therefore, showers
and any storms will be relatively weak, but a few pockets of gusty
outflow winds possible given DCAPE of 1000-1400 J/kg.

We have some weak upper level support in the form of QG and mid
level frontogenesis to keep a few showers and storms going
through midnight, and even into the late night/early Friday
morning hours over the northeast corner.

On Friday, after any morning convection leaves the northeast
corner, we`ll be hotter, drier, and more stable. There will be a
band of higher low level moisture/MLCAPE on the northeast plains
just east of a pseudo-dryline/mixed environment, so just a 20%
chance we could pop off a storm along that boundary and then
eventually tap into the deeper moisture and instability to the
east. The SPC Marginal Risk seems a bit much, but still something
to watch for an isolated strong/severe storm threat.

Temperatures will heat up further tomorrow, with highs pushing
into the lower to mid 90s across the plains, except the far
northeast plains.

&&

.LONG TERM /Friday night through Thursday/...
Issued at 250 PM MDT Thu Aug 15 2024

Saturday will be the warmest and driest day of the long term
period. A 500 mb ridge with heights around 598 dm will be centered
over norther New Mexico. Subsident flow from this ridge will
limit cloud cover and add to compressional warming. Highs will
increase to the mid to upper 90s across the plains. The forecast
for Denver still calls for a high of 97 which is a degree short of
the daily record high. Ensemble data supports a temperature
around 97 and the thinking is that the GFS MOS forecast high of 99
for KDEN is too warm. There will be high lapse rates which may
allow for a few light showers to form in the afternoon. More wind
than rain would be expected from these showers.

The upper level ridge will drift eastward on Sunday and southeast
to east winds will develop at the surface across the plains. This
upslope low level flow will be aided by a high pressure system
that will be located over Nebraska. This will push moisture
farther westward up against the foothills. Moderate instability
will develop across much of our forecast area and storms will form
over the higher terrain in the afternoon thanks to the orographic
flow. As the storms drift eastward, they will encounter an
environment that will be more capped. As a result, storms will
struggle to persist across the plains although some areas will see
gusty winds and brief heavy rainfall. The primary threat will be
the chance of flash flooding over the recent burn areas.

The upper level ridge will barely move Monday through next
Thursday. Persistent weather conditions will be over Colorado as a
result. Each day will have highs that are a few degrees above
normal with highs in the low to mid 90s across the plains. Healthy
moisture will be in place and this will help to generate daily
showers and thunderstorms. Storms will be slow moving and may
produce brief heavy rainfall. The burn areas will see a daily
threat of flash flooding and it is too early to tell which days
might have an elevated threat compared to a limited threat. For
the most part, storms will be short-lived on the plains but gusty
winds, small hail, and brief heavy rain will be possible from any
storm.

&&

.AVIATION /00Z TAFS through 00Z Saturday/...
Issued at 528 PM MDT Thu Aug 15 2024

High based showers, and possible weak thunderstorms are expected
to prevail through at least 06Z. Main issue with this will be
gusty outflow winds producing wind shifts at the airports. Skies
clear overnight with mostly clear skies expected for Friday. As
far as winds go, southeast winds are expected to continue through
much of the evening. There`s been a general consensus among the
models that outflow from convection to the north of Denver brings
a northerly wind shift late this evening or overnight.

&&

.HYDROLOGY...
Issued at 250 PM MDT Thu Aug 15 2024

Isolated to scattered showers and storms will continue tonight,
but intensity will be limited by lack of instability and less
moisture content in the atmosphere. Thus, threat of even burn scar
issues is very low tonight.

A dry pattern will prevail Friday and Saturday, with nothing more
than a possibility of isolated, weak showers in the high country
leading to a negligible threat of flooding for the burn scars.

The flash flood threat returns Sunday as we receive a considerable
influx of monsoonal moisture. The primary concern will be a
limited or higher threat of flash flooding on the recent burn
areas. This is because storms will be slow moving and the chance
for storms to develop over the foothills is rather high.
The pattern doesn`t appear supportive of successive days of
efficient rain producers, so the threat for flooding as lower
elevations is low.

&&

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

&&

$$

SHORT TERM...Barjenbruch
LONG TERM...Danielson
AVIATION...Meier
HYDROLOGY...Barjenbruch/Danielson