283
FXUS65 KBOU 250548
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1148 PM MDT Wed Jul 24 2024

.KEY MESSAGES...

- Smoky skies should show slight improvement Thursday. After that,
  further improvement will depend on fire activity in the
  northwest U.S.

- Increased rainfall chances for Friday and Saturday, then dry.

- Elevated to potentially critical fire weather conditions are
  expected over the higher terrain on Sunday due to hot, dry, and
  windy conditions.

- Long period of very hot temperatures through much of next week.

&&

.UPDATE...
Issued at 657 PM MDT Wed Jul 24 2024

Updated for cloud cover making it a bit further east and a bit
more solid that what we had. We should still see pretty good
clearing by the middle of the night.

&&

.SHORT TERM /Through Thursday/...
Issued at 245 PM MDT Wed Jul 24 2024

Satellite and radar shows the convection evolving pretty much as
anticipated, with scattered showers and isolated weak storms
developing over the mountains. Those will dissipate rather quickly
with the loss of daytime heating and weak subsidence in place.
Skies will then clear thereafter, with temperatures settling back
to close/slightly above normal lows.

On Thursday, temperatures aloft warm another ~1.5C as the upper
level high over the Great Basin elongates over Colorado. At the
same time, smoke concentration is expected to wane as mid level
flow turns a bit more N/NW - advecting in a little less smoke from
Wyoming. The combination of the warm advection and lighter smoke
concentrations would support another 4F of warming, which would
equate to high temperatures reaching the upper 90s across all of
the plains. Only an isolated shower possible over the mountains,
with a drier airmass prevailing across the forecast area.

&&

.LONG TERM /Thursday night through Wednesday/...
Issued at 208 PM MDT Wed Jul 24 2024

A strong ridge that is currently over the western US will weaken and
move south towards Baja California on Friday. This is due to a
trough that will move from the Pacific Northwest towards Wyoming and
far northern Colorado. This trough will have decent moisture
associated with it and the timing of it aligns well with peak
heating. These factors will combine to create scattered to
widespread storms over the higher terrain on Friday afternoon.
These storms will propagate onto the urban corridor and plains but
will lose intensity as they move away from the mountains due to
less instability. Some of these storms could produce brief heavy
rainfall and the recent burn areas will see a limited threat for
flash flooding. Otherwise, temperatures will be 3-6 F above
normal.

On Saturday, another shortwave trough will move through our forecast
area. A wave of showers and storms will develop in the afternoon and
evening. These storms will once again produce brief heavy rainfall
but are not expected to become severe due to lack of instability and
shear. Highs will be a couple of degrees above normal.

As the shortwave moves out of the area Saturday night, there will be
subsident flow on Sunday. In addition, much drier air will move in
from the west. This will greatly decrease the chance for storms and
the vast majority of our forecast area will be dry. The concern on
Sunday will be fire weather. Wind gusts could reach 35-40 mph across
the higher terrain due to the stronger flow aloft. At the same time,
relative humidity will drop to the teens in the higher
elevations. This will lead to elevated or perhaps critical fire
weather conditions.

The story for next work week will be heat. A ridge will build
over the Intermountain West that will be anomalously strong. The
subsident flow under this ridge along with the warm temperatures
aloft will allow for very hot temperatures to develop. If there is
not much wildfire smoke that moves over Colorado during this
period, temperatures will have a chance to reach record highs. The
ECMWF Extreme Forecast Index confirms this potential as the urban
corridor has over an 80% chance of seeing max temperatures at the
warm extreme of the range from the last 20 years. Denver record
highs are 99, 101, and 100 respectively on July 29-31. The current
forecast for Denver is exactly 2 F below those records each day
but in these scenarios the models typically trend toward warmer
solutions. Otherwise, minimal shower and storm activity is
expected during this period.

&&

.AVIATION /06Z TAFS through 06Z Friday/...
Issued at 1147 PM MDT Wed Jul 24 2024

Smoke will likely linger around through Thursday, although
thinner than the previous few days. Kept the mention of FU in the
TAF through Thursday evening.

SSE winds become S/SSW around or just after 06Z at 8-15 kts. Winds
shift to SSE by the afternoon at DEN/APA and SE at BJC. Later in
the afternoon through the evening, winds increase out of the
SSE/SE with gusts up to 20-23 kts at APA/DEN.

&&

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

&&

$$

UPDATE...Gimmestad
SHORT TERM...Barjenbruch
LONG TERM...Danielson
AVIATION...Mensch