343
FXUS65 KPUB 211002 CCA
AFDPUB

Area Forecast Discussion...CORRECTED
National Weather Service Pueblo CO
402 AM MDT Tue May 21 2024

.KEY MESSAGES...

- Scattered showers and thunderstorms will develop later today,
  mainly north of Highway 50. A stronger storm or two is
  possible.

- High elevation snow will allow for a few more additional
  inches, mainly over the Sawatch Range and northern Sangre de
  Cristo Mountains.

- Gusty winds due to frontal boundary later in the afternoon
  through early evening over the plains. Cooler highs today.

- Enhanced fire danger on Thursday.

- Slightly better chance for showers and thunderstorms across
  the central mts, Pikes Peak region and the Palmer Divide
  Friday through Sunday.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 337 AM MDT Tue May 21 2024

Today...

Currently, there are some areas of post-frontal morning low clouds
and fog over El Paso County, especially over the Palmer Divide, in
vicinity of monument. This will continue to dissipate as the lower
levels mix out this morning.

An U/L low pressure system positioned over the northwestern region
will continue to slowly propagate eastward, which will allow for an
associated wave embedded within the trough to move over by later in
the afternoon. This feature, along with orographic lifting, will
kick off some storms by later in the day, initially over the higher
terrain, and then this will move off the mountains into the plains
by later in the afternoon and through the early evening hours due to
strong westerly mid-level flow. There will also a frontal boundary
moving through later this afternoon through early evening across the
plains, which will help to advect in some cooler temperatures and
bump up humidities. The boundary and upsloping behind it also may
help to also trigger some more convection. The timing of this looks
to be around 4 to 5 PM over El Paso County, and then makes its way
over the lower Arkansas River Valley by around 6 PM. This passage
may also occur sooner if it is accelerated by convective outflows.

The latest HREF paintballs put a majority of the convection
occurring north of Highway 50, given that this is where there is
better moisture content and slightly more unstable. Characteristics
for instability are highly effective for some attributes, and
lacking for others. There is going to be a lot of effective bulk
shear, as well as steep lapse rates, although MUCAPE is relatively
weak, with the best values over El Paso County being around 700
J/kg. Due to this, confidence is low of something becoming severe.
However, given the amount of bulk shear at over 80 kts across the
Ramparts, a storm becoming severe cannot be ruled out. Main threat
if this does occur will be hail of possibly an inch or greater, and
gusty outflow winds up to 60 mph. If storms just remain on the
stronger side, hail up to nickel size will be possible, as well as
gusty outflow winds to 50 mph. DCAPE values initially around the
time of convection initiation are also around 1000 J/kg over
portions of the I-25 corridor north of Highway 50. Therefore, some
of these heavier showers and thunderstorms could create outflows and
enhance the already gusty surface winds out of the west across the
plains, and may result in winds occasionally approaching severe
criteria as a result. There will also be some high elevation snow,
which may provide a couple of additional inches, especially over the
Sawatch Range and northern Sangre de Cristo Mountains.

Winds will generally be strong and gusty across all of the CWA,
although RH values will be modified by the recent frontal passage to
keep most of the areas below 7500 ft in vicinity of the Sangres and
Wets and within the Wet Mountain Valley (where fuels are still
critical) above the threshold and therefore no consideration to go
with a Red Flag Warning at this time. That being said, there may
still be some areas which occasionally experience critical fire
weather conditions, so it is best to still avoid outdoor activities
which could cause a spark if you reside within these areas. A cooler
airmass is in place, although with downsloping winds will keep
things more mild for the plains. Still, it will be around 10 to 15
degrees cooler from where max temps were yesterday.

Tonight...

Winds will decouple and begin to weaken by later this evening as the
shortwave continues to move away from the region. Skies will also
continue to clear. This will allow for some sufficient radiational
cooling to take place, with temperatures dropping off into the upper
30s to mid 40s across the plains. For high country, it will
generally get down into the 20s to low 30s, although there could
also be some locations across the highest elevations and within the
high mountain valleys that make it into the upper teens.   -Stewey

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 337 AM MDT Tue May 21 2024

Wednesday...Upper system passes to the east overnight Tue into Wed,
with lighter westerly flow aloft then settling in for the state.
Residual moisture will help spark isolated showers and thunderstorms
by mid-afternoon along the eastern mts and I-25 Corridor, which will
then push off across the eastern plains through the evening. High
temps are forecast to warm to seasonal normals or just below, with
60s to around 70F for the high valleys, and upper 60s to upper 70s
for the plains.

Thursday...Another upper low strengthens over ID Thu morning, then
quickly crosses MT and WY through the day. This will tighten the
pressure gradient across CO and increase southwest flow aloft across
the Four Corners. The increased downslope west to southwest wind
will help boost temps to above seasonal normals, with highs in the
upper 60s to mid 70s for the high valleys, and upper 70s to upper
80s for the plains. While there will be some isolated shower
activity across the central mts, the rest of the area will stay dry
with widespread humidity levels dropping into the 10 to 15 percent
range. The lower elevations of the Sangres and the Wets will likely
need a fire weather highlight if this trend continues.

Friday through Monday...A cold front passage Thu evening will cool
high temps on Fri a bit, then a quick-moving upper shortwave will
cross the Desert Southwest Sat, followed quickly while another low
system to the north for Sun. This will keep the best chances for
precipitation across the central mts, the Pikes Peak region and the
Palmer Divide. The remainder of the area will likely just see
isolated convection at best during the afternoon and evening each
day. Long range models disagree on what the low system to the north
does on Sun leading into Mon, but there is plenty of time for that
to get sorted out. Plan on temps each day to hover around seasonal
normals, with Fri being the coolest and then a degree or two warming
each day Sat through Mon. Moore

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 337 AM MDT Tue May 21 2024

VFR conditions are expected to prevail for KALS and KPUB, and mostly
for KCOS, throughout the forecast period. Winds will be synoptically
influenced by an approaching system, which will cause winds to
become rather gusty out of the SW tomorrow at all terminals, with
gusts as high as 35kts at KALS, 32kts at KCOS and 40kts at KPUB.
There will be FROPA at 08Z and KPUB, but may come a little sooner
depending on acceleration of the front. This will cause winds to
shift to a NNW-NNE`ly direction at KPUB. Then will return to a S-
SW`ly direction again tomorrow at KCOS and W`ly direction at KPUB,
then there will be FROPA occurring again at KCOS around 23Z and KPUB
around 00Z, which will cause winds to shift back to a N-NNE`ly
direction. Winds will be strong and gusty tomorrow afternoon out of
the SW at KALS, then come around to the NNW by evening. There could
also be some -SHRA moving on station and possibly VCTS tomorrow
afternoon at KCOS, with lesser confidence of occurrence at KPUB. If
SHRA/TSRA does develop, it could temporarily reduce CIGs and VIS to
MVFR/IFR criteria. It could also result in periodic windshifts and
increased wind speeds. Winds will weaken through the late evening
and on, becoming more diurnally influenced towards the end of the
forecast period. -Stewey

&&

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

&&

$$

SHORT TERM...STEWARD
LONG TERM...MOORE
AVIATION...STEWARD