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073
FXUS65 KPUB 290113
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
713 PM MDT Tue May 28 2024

.KEY MESSAGES...

- Strong to severe storms possible this afternoon and evening
  southeast plains with greatest risk across Kiowa, Bent,
  Prowers and Baca Counties.

- Severe thunderstorm risk expands across all of the southeast
  plains on Wednesday.

- Showers and thunderstorms will develop during the afternoon,
  with severe storms possible over the plains, on Thursday.

- Afternoon thunderstorms will be possible on Friday, but less
  of a chance of becoming severe.

- It will be drier this weekend going into early next week with
  a lesser chance of afternoon thunderstorms.

&&

.UPDATE...
-- Changed Discussion --
Issued at 707 PM MDT Tue May 28 2024

Updated to cancel the Severe Thunderstorm Watch early for our
Eastern Plains zones. A few weak thunderstorms, capable of
producing small hail and gusty winds will remain possible
through 9 PM, the convection from earlier this evening has
worked to stabilize the atmosphere. Therefore, the risk of
severe weather has diminished.  Mozley
-- End Changed Discussion --

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 222 PM MDT Tue May 28 2024

Southeast winds have been advecting 40-50+ dew points westward into
southeast CO this afternoon with ML CAPEs off Meso Analysis up to
2000 J/kg across the far eastern plains of Kiowa, Prowers, Bent and
Baca counties. Meanwhile, convective temperatures have been breached
across the Palmer and Raton Mesa regions.  Lower dew points out west
point to more of a wind and small hail risk for the I-25 corridor
and adjacent eastern plains this afternoon.  However as storms move
eastward and develop along surface boundaries, healthy CAPE and
sufficient shear in the 30-40 kt range, will result in a few strong
to severe storms which may congeal into one more more convective
clusters across southern portions of the plains, with less certainty
farther north with cells across Kiowa county later this evening. SVR
Watch #346 will remain in effect until 9 PM.  Thunderstorms diminish
across the eastern plains this evening but will likely send an
outflow boundary westward into the I-25 corridor towards morning.
This will set the stage for better thunderstorm chances on
Wednesday.

Upper ridge axis shifts eastward on Wednesday as the western U.S.
upper trough moves into the Great Basin and northern U.S. Rockies by
afternoon.  Storms will re-fire across the mountains around noon, and
spread eastward across the plains during the afternoon.  Mean HREF
CAPE increases to around 1000 J/kg along the I-25 corridor with
1500+ across the far eastern plains.  NAM12 still rides on the
higher side of the spectrum with SBCape up to 2500 J/kg.  With a
little better flow aloft, deep layer shears will range from 30-40
kts, sufficient for a few strong to severe thunderstorms with large
hail and damaging winds possible.  Thunderstorms may persist into
the evening hours if a convective cluster can organize over the
eastern counties as low level jet strengthens during the evening.
Activity should be pushing south and east of the area during the
overnight hours.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 222 PM MDT Tue May 28 2024

Thursday...

A major shortwave trough located to the north of the region will be
propagating towards the east. This will allow for there to be a
southwesterly flow in the mid levels and a sufficient amount of
upper level diffluence to provide lift and help to initiate
thunderstorm development during the afternoon over the region. This
will also interact with an associated frontal boundary with the
trough, which will enhance thunderstorm activity over the plains by
later in the afternoon and through the evening. It will be rather
conditionally unstable over the plains as southeasterly winds ahead
of the boundary during the morning allows for more low-level
moisture and relatively higher dewpoints to make its way further
west and back up against the I-25 corridor. As a result, MUCAPE will
continue to increase, with values approaching 3000 J/kg showing up
in some over the models over portions of the far southeastern plains
and just over 2000 J/kg stretching back into the lower Arkansas
River Valley and up to the I-25 corridor in Pueblo County. There
will also very favorable lapse rates for updraft intensities,
generally between 7 to 8 C/km over the plains. The one component
that will be lacking is going to be effective bulk shear, which will
be around 30 to 35 kts over most of the plains, and only some better
values of 50 kts or greater confined to a more isolated area near
the Raton Mesa. Still, the potential will be there for storms to
become severe, especially over the far southeastern plains where
some of the better CAPE will be. Low-level shear/CAPE is not
going to be very impressive, and therefore the threat of
landspouts will be very low, but cannot be ruled out.

Lastest CAMs display most of the initial thunderstorm development to
be over El Paso County and western Las Animas County, and then moves
eastward and intensifies. There is also going to be the possible
formation of an MCS which develops over the Palmer Divide area and
then drops down to the southeast and affects Kiowa and Prowers
counties by later in the evening. If this occurs, it may produce
severe outflow winds along a gust front ahead of it. The other main
impact from these storms will be the threat of very large hail,
given the amount of MUCAPE, which may be up to an inch or more for
locations along the I-25 corridor and possibly greater than 2 inches
over the eastern plains. These storms will continue to progress
eastward, with a greater chance of becoming severe as they get
closer to the CO/KS border. There could still be some storms
continuing within our CWA up to a few hours after midnight and then
should be completely to our east just before sunrise on Friday.

Friday through Monday...

As the major shortwave continues to move off to the east and further
downstream, it will allow for overall more stable conditions to
return to the plains. However, the westerly flow with some recycled
moisture and orographic lifting will spark off convection during the
afternoon, mainly over the eastern mountains and along the I-25
corridor and then will move off to the east as the evening
progresses. Given the relatively more stable environment, with
weaker shear, storms will likely not become severe but may still be
on the stronger side with possibly hail up nickel size and gusty
outflow winds up to 50 mph. A weak ridge will continue to build in
over the region during the weekend and this will help to suppress
afternoon convection somewhat, although there will be recycled
moisture and westerly flow remaining in place with storms being more
isolated in nature (mainly over the mountains and far eastern
plains) and overall warmer and overall drier for most locations.
Sunday will be the hottest day as the ridge axis moves over and an
approaching trough creates downsloping winds, with highs maxing out
in the mid 90s over much of the plains. There could also be some
fire weather concerns for the lower elevations in vicinity of the
southern Sangres. It will be slightly cooler but still relatively
dry on Monday after passage of the trough, although there will still
be. some afternoon thunderstorms possible, mainly over the mountains.
-Stewey

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 529 PM MDT Tue May 28 2024

KALS...VFR conditions through the next 24 hours. A few wind
gusts near 20 kts will be possible this evening, dissipating
overnight into Wednesday. There could be a couple of showers
across the San Luis Valley, but should not impact the terminal.

KCOS and KPUB...a few showers/thunderstorms will remain possible
this evening with brief impacts to CIGS and VIS if they move
across the terminals. Southeasterly flow will lead to low CIGS
overnight at both terminals, clearing out by morning. Another
round of showers and thunderstorms will be possible Wednesday
afternoon.  Mozley

&&

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

&&

$$

UPDATE...MOZLEY
SHORT TERM...KT
LONG TERM...STEWARD
AVIATION...MOZLEY