910
FXUS65 KBOU 211153
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
553 AM MDT Fri Jun 21 2024

.KEY MESSAGES...

- Scattered to likely showers and thunderstorms through this
  evening with heavy rainfall the main threat. Burn scars would be
  most susceptible to flash flooding.

- Hotter and drier this weekend into early next week.

&&

.SHORT TERM /Through tonight/...
Issued at 335 AM MDT Fri Jun 21 2024

There should be one more day of showers and thunderstorms along with
seasonal temperatures.

Radars are showing some weak convection continuing over the CWA
this early morning and some over the southwestern quarter of Colorado
as well.

Models are showing an upper trough over the Great Basin this morning
to weaken and move eastward into Colorado by this evening into the
overnight hours. The flow aloft will remain southwesterly across
the forecast area today and tonight. There is a short period of
weak upward synoptic scale energy expected later this afternoon
and evening.  Models continue to show significant available
moisture today into this evening with precipitable water values in
the 0.80 to 1.50 inches range. The atmosphere looks to dry out
somewhat after 06Z overnight. There is plenty of CAPE progged for
the CWA with the highest amounts over the northern border area.
Will go with 30-60% pops for the forecast area this afternoon and
evening. There will be a few strong storms but the main threat
will be heavy rainfall with a flash flooding potential. One good
thing is the convection will be moving at 20-30 mph to the
northeast.

For high temperatures today, readings will be 1-4 C cooler than
Thursday highs with mid and upper 80s over the plains a good bet.

&&

.LONG TERM /Saturday through Thursday/...
Issued at 246 AM MDT Fri Jun 21 2024

Upper level ridge will intensify over the Central and Southern
Rockies this weekend. Highs will top out around 90F on Saturday,
and then heat up for Sunday and Monday. For the Urban Corridor and
northeast plains highs are expected to reach the mid to upper 90s
with a few 100s possible as well. Good chance for heat advisories
Sunday and/or Monday. Precipitable water values will be on the
low side for convection with three-quarters of an inch across the
plains and under a half inch over the higher terrain. The higher
terrain may have just enough moisture and instability for weak
afternoon showers and thunderstorms through Monday. For the
plains, a few weak showers/storms may move off the higher terrain
bringing more wind than rain. One exception will be Sunday
afternoon/evening over the eastern plains. Southerly winds advect
better low level moisture into Lincoln county. This combined with
lift from a possible boundary could produce a few afternoon
storms.

For Tuesday through Thursday, an upper level trough moves across
the Northern plains Tuesday. The 00Z operational runs show a cold
front from this trough moving through Tuesday morning. Expect
temperatures to take a step back with highs in the upper 80s to
lower 90s. Seems like the ensemble members are not showing this
yet. Some of the guidance that incorporates the ensemble members
still show highs in the mid to upper 90s for Tuesday, which seems
high. Moisture is still not that great from the models so will
keep PoPs on the lower side on Tuesday. Models finally show an
increase in moisture for Wednesday and Thursday, so we should see
at least scattered showers and storms.

&&

.AVIATION /12Z TAFS through 12Z Saturday/...
Issued at 552 AM MDT Fri Jun 21 2024

Weak and variable winds are still in place at DIA this morning.
Models show weak easterly winds much of today with somewhat
normal drainage wind patterns kicking in around 04Z tonight.
Models are showing fairly decent convection this afternoon and
evening so I went with two TEMPO groups of -TSRA. Ceilings could
be BKN050-060 with the storms along with variable winds gusts up
to 35KT.

&&

.HYDROLOGY...
Issued at 335 PM MDT Thu Jun 20 2024

There will be a threat of flash flooding with the convection this
afternoon and evening. Precipitable water values are quite high
and the storms should produce heavy rainfall. However, the
thunderstorms will be moving at 20-30 mph to the northeast which
will lessen the threat of flooding. The alpine burn scars should
be most susceptible to the flash flooding threat as well as areas
of training thunderstorms.

&&

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

&&

$$

SHORT TERM...RJK
LONG TERM....Meier
AVIATION...RJK
HYDROLOGY....RJK