041
FXUS65 KPUB 220452
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
1052 PM MDT Fri Jun 21 2024

.KEY MESSAGES...

- Drier and warmer pattern expected through Tuesday with
  isolated mainly mountain thunderstorms and temperatures
  reaching 100-105 again across the southeast plains next week.

- Another uptick in thunderstorms possible mid to late week.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 239 PM MDT Fri Jun 21 2024

Anomalously high moisture over the region (PWATs 200-250%+ of
normal) ahead of a shortwave trough will provide plenty of fuel for
strong to severe thunderstorms across the mountains and valleys
through this evening with heavy rainfall and flash flooding the
primary concerns.  Soils are most saturated over the Eastern San
Juans were a little over an inch of rain fell yesterday afternoon
through last night. A Flash Flood Watch remains in effect for this
area until midnight. Cloud cover has hampered heating across this
area today as well as across portions of the central mountains which
has limited instability.  But as cloud breaks and surface heating
occurs, odds for severe thunderstorms will increase as the afternoon
and evening continue.  High res models develop a couple rounds of
convection, one which is moving through the mountains now, and
another which is associated with the stronger forcing with the upper
trough axis this evening through tonight.  This latter wave may be
the one to bring the heavier rainfall to the eastern San Juan
mountains.  Mean QPF from HREF suggests another inch of rain could
fall across the eastern San Juan mountains with up to 0.5 inches
elsewhere across the remainder of the mountains and valleys.  90th
percentile QPF shows up to 1.75 inches of rain across the Southwest
mountains and west slopes of the southern Sangre De Cristo range
which would be the higher side of possibilities.  Stronger shear and
CAPE today will lead to one or two strong to severe storms across
the mountains as well.  Storms have been and will continue to be
relatively quick moving (around 25-30 mph) but storm intensities
and antecedent soil moisture could result in flash flooding for the
more susceptible areas elsewhere across the mountains such as burn
scars, and the Chalk Cliffs.  Rock slides will be possible across
the steeper terrain as well.  So far rises on the gaged smaller
creeks in the eastern San Juans have remained within banks and below
action stage with additional room for rainfall.  So far it still
appears that storm intensity and rainfall rates may be the primary
driver for flash flooding for these areas.

As storms move off the mountains into the adjacent plains late this
afternoon and evening, storms will become more higher based as dew
points have been mixing out into the 40s east of the mountains.
Downdraft CAPE of 1000-1300 J/kg will lead to more of a high wind
risk (gusts to around 60 mph) from the stronger cells along the I-25
corridor, however some small hail (up to an inch) could fall along
the lower eastern slopes of the southeast mountains.

Activity should diminish after midnight as the trough axis shifts
eastward and drier air works in from the north.  Clouds and showers
will be latest to clear across the southern mountains.

Saturday will be drier and warmer, but there will still be
sufficient moisture for afternoon and evening showers and
thunderstorms.  These will be higher based and less conducive for
producing heavy rainfall and flash flooding.  However there may
still be sufficient lingering low level moisture to yield CAPE up to
1000 J/kg and deep layer shears are progged to be around 30-40kts.
So we may still have a strong storm or two over the mountains and
valleys depending on how quickly this low level moisture mixes out.
East of the mountains, thunderstorm chances fall off quickly and
these will be high based with gusty winds and lightning the primary
risks.  Thunderstorms will diminish quickly with loss of heating
Saturday evening.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 239 PM MDT Fri Jun 21 2024

The heat continues to build for Sunday through Tuesday as the upper
ridge builds northward back over southern CO. H7 temperatures +18 to
+21 C will result in max temps back in the mid 90s to 105 degree
range over the southeast plains with 80s for the valleys and 60s and
70s for the higher mountains/mountain communities.  Monday and
Tuesday could see more Head Advisories for portions of the I-25
corridor and southeast plains depending on these details, and this
risk will be monitored closely.  Fortunately, winds look relatively
light which should mitigate any critical fire weather potential even
though relative humidity values will be quite low in the afternoons.
There will still be enough mid/high level moisture present for
isolated high based thunderstorms each day, mainly across the
mountains. Gusty winds and lightning with little to no rainfall
would be the primary risks.

Upper high picks up some subtropical moisture Wednesday into the
latter part of next week which will bring increasing moisture and
better chances for thunderstorms to the region especially Thursday
into Friday as moisture quality increases.  This will take the edge
off temperatures some, but temperatures will still remain hot with
highs 5-10 degrees above normal.  Models advertise another upper
trough for next weekend which shunt the moisture plume to the east
and south once again so any uptick in thunderstorms late week
appears temporary. -KT

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 1047 PM MDT Fri Jun 21 2024

At KALS, still a risk of a vcsh until around 08z, then precip
and clouds slowly fade away into Sat morning. VCTS returns after
20z as storms move off the higher terrain, though coverage
should be less than the past few days.

At KPUB and KCOS, VFR the next 24 hrs. Will keep any mention of
convection out of both forecasts at this point, though there is
a minor chance of some weakening mountain storms drifting toward
both sites after 23z Sat. Winds will settle out to typical
drainage through Sat morning, then swing around to usual diurnal
upslope from midday Sat into Sat evening.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SHORT TERM...KT
LONG TERM...KT
AVIATION...PETERSEN