000
FXUS65 KBOU 070527
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1127 PM MDT Tue Jun 6 2023

.UPDATE...
Issued at 800 PM MDT Tue Jun 6 2023

Showers and storms have pretty much ended with only isolated
activity near the WY border and over swrn Lincoln county. Based on
current trends these should end in the next hour or so. Otherwise
only minor adjustments for the rest of tonight.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 245 PM MDT Tue Jun 6 2023

There are scattered showers and thunderstorms over the mountains
and foothills at this time, with no convection yet over the
plains. The heaviest rainfall rates so far are up to 0.50 inch per
half hour. The high resolution models bring the convection into
the plains by 00Z. Everything is done around 06Z.

Looking at Wednesday, the upper ridge center is over the Dakotas
with weak southeasterly flow aloft for the CWA.  More of the same.
There is weak upward vertical velocity on the QG Omega fields for
Tuesday.  Moisture is a tad higher on Tuesday on the precipitable
water fields, more so over the mountains with 0.80 inch progged for
most areas. MLCAPE is up to 1500 J/kg by Tuesday afternoon over
some of the CWA. Will leave the current GFE grids pretty much
alone with 70-90% pops in the mountains and 30-70%s over the
plains and foothills. Water issues are possible. For temperatures,
Tuesday`s highs look similar to this afternoon`s readings.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 142 PM MDT Tue Jun 6 2023

Wednesday night, the closed upper low will be over southern CA/NV
with a weak disturbance possibly moving northward through CO
Wednesday evening. Higher precipitable water values should
continue through the evening, with layer PWAT values 0.60- 0.80
inch in the mountains. Weak diffluent flow aloft with forecast
sounding show a deep moist layer with southeast winds near 10 kts.
All this said, the threat of flash flooding will likely be more
in the elevated category over the East Troublesome and Cameron
Peak burn scars. WPC excessive rainfall analysis, shows a slight
risk of exceeding flash flood guidance in the mountains/foothills.
The threat of thunderstorms will be much lower across the
northeast plains as the steering winds will keep the storms
closer to the higher terrain.

Thursday and Friday, the amplified blocking ridge will remain
over the central U.S. The closed upper low will shift into the
Great Basin a bit more. This may allow the mid/upper level winds
to shift from southerly to southwesterly where it could advect
somewhat drier air back into the region. The threat of storms with
locally heavy rainfall will continue but the overall coverage
should be less, generally in the scattered category.

Over the weekend, the models show the ridge axis over the northern
plains, with a trough and its associated cold front moving across
the Midwest.  This front will push into northeast CO Saturday
afternoon or evening. Northeasterly post frontal upslope winds will
again elevate the risk of thunderstorms in the mountains and
foothills.  The higher PWAT values will continue to remain elevated
from the Front Range eastward across the plains through Sunday. The
closed upper low will continue to keep a diffluent south/southwesterly
flow over the region, with good shower/tstm coverage across the
mountains and the plains.

The cool and unsettled weather will continue into next week.  The
blocking ridge over the central U.S. will eventually break down as
the closed upper low finally moves into the Central Plains Tuesday
into Wednesday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1127 PM MDT Tue Jun 6 2023

Quiet weather conditions expected through Wednesday morning. High
clouds to thin out by sunrise. Southerly drainage winds to prevail
through about 13Z and then slowly become easterly by 16-17Z.
Another round of late day thunderstorms are expected, best chance
for storms will be 22-02Z. Brief heavy, small hail, and winds to
35 knots will be possible with the stronger storms. Even if a
storm doesn`t move overhead, outflow winds will likely produce a
wind shift or two.

&&

.HYDROLOGY...
Issued at 245 PM MDT Tue Jun 6 2023

This evening`s alpine convection will bring an elevated threat for
flooding mainly in the burned areas. On Wednesday afternoon, with
increased moisture expected will bring a significant threat of
flooding in the burned areas with widespread pops in the
forecast.

Well above normal precipitable water values will be in
place Wednesday night coupled with a light and deep southeasterly
flow aloft. These conditions could maximize the risk of flash
flooding over the East Troublesome and Cameron Peak burn areas.
The storm coverage should be lower on Thursday and Friday but a
limited threat of flash flooding will exist in the burn areas each
day.

Precipitable water values will increase during the weekend along
with upslope flow and a cold front. All of these factors will lead
to widespread coverage of showers and storms. An elevated threat for
flash flooding will likely return to the burn areas. The plains
could also see a flash flooding threat as well due to so much
moisture in the ground and expected heavy rainfall rates.

&&

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

$$

UPDATE...RPK
SHORT TERM...Koop
LONG TERM...Coop
AVIATION...Meier
HYDROLOGY...Koop/Coop