249
FXUS65 KPUB 200947
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
347 AM MDT Mon May 20 2024

.KEY MESSAGES...

- Critical fire weather conditions this afternoon for the lower
  elevations of the Sangres and the Wets.

- A few strong to severe storms could develop over the far
  eastern plains later this afternoon.

- Snow showers will be increasing across the higher terrain,
  especially for the central and southwest mountains.

- Isolated to scattered showers expected for the higher terrain
  and Palmer Divide through the week, with mostly dry conditions
  elsewhere.

- Enhanced fire danger on Thursday.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 339 AM MDT Mon May 20 2024

Today...

An approaching low pressure system will allow for strong and gusty
southwesterly winds to take over for most of the region by later
this morning. This will allow for a drier air mass to move in and
cause relative humidities to tank. Due to this, there will be
critical fire weather conditions for the elevations of 7500 ft and
less in vicinity of the Sangres and within the Wet Mountain Valley,
where fuels are still critical by later this afternoon and through
early evening. Currently there are some low clouds and fog over the
far eastern plains which will dissipate after sunrise but also leave
the PBL quite saturated. There is going to be a dryline boundary
establishing itself out over the far eastern plains the very juicy
and unstable air in the lower levels remains locked in the
southeasterly flow. With this, dewpoints reaching to near 60F right
along the CO/KS border as a low-level moisture tongue extends back
to the west ahead of the associated surface low as it positions
itself over northeastern Colorado and then undergoes lee-side
cyclogenesis. There will be a fair amount of convective inhibition
(capping) in place over the far eastern plains, however, if the
convective temperature is achieved and the capping is broken, there
could be some type-a (loaded gun) storms that could develop quickly
and possibly become severe. If these severe storms do occur, they
could be capable of producing very large hail of 2 inches or
greater, as well as strong and gusty outflow winds of 60 mph. Some
of the compelling factors that give credence to storms becoming
severe are effective bulk shear winds of greater than 70 kts, as
well as steep lapse rates in excess of 9C/km, and MUCAPE of more
than 3000 J/kg for all locations just east of the dryline.

When analyzing the latest CAMs, a consensus of them puts the
position of the dryline somewhere right around La Junta and extends
down to the southeast around Springfield. If storms do initiate
along the boundary, this will likely be the location where these
storms go. The HRRR, with its overly dry and mixing bias, keeps all
of the far eastern plains dry, whereas the NAMNest does put a few
cells developing over Bent to Kiowa County around 4 PM and then
racing off to the northeast. Sigtor values approaching 1 are
reflected with the HRRR and GFS just to the east of the Kansas
border, and given the amount of low-level instability and 0-1km SRH
values approaching 100 m^2s^-2 over these three counties right at
the time of in, a brief landspout or weak tornado cannot be ruled
out. HREF paintballs also put the highest concentration of cells
capable of becoming severe right on the northeast corner of the CWA,
mainly Bent, Prowers, and eastern Kiowa counties. This will be the
area to watch later today. If CIN remains and the cap is strong
enough to prevent convection, most of the plains should remain dry,
with the only exception being a possible storm ot two developing
over the Palmer Divide area. There could also be some showers and
high elevation snow showers increasing across the higher terrain,
mainly for the central and southwest mountains.

Given the downsloping winds, it will get very warm today across the
lower elevations and especially the plains, where there could be
locations within the lower Arkansas River Valley topping out in the
low to mid 90s. Elsewhere across the higher terrain, it will be
relatively cooler, which highs generally in the 40s to 50s, and 60s
for the higher mountain valleys.

Tonight...

Any storms that develop will continue to move off towards the
northeast and eventually out of the CWA into Kansas by later this
evening. There will still be some mountain snow showers continuing
as the U/L low associated with the major shortwave trough propagates
overhead. A cold frontal boundary on the backside of the low as it
moves into southwestern Nebraska will move down from the north
across the plains. This will result in strong and gusty winds out of
the northwest to northeast to advect in cooler temperatures and also
help to recover RH values. With higher dewpoints after passage of
the front and some mid level clouds still in place, temperatures
will be more modified and therefore only dropping into the low to
mid 50s for most of the plains, with only 40s for the higher
locations where it will be slightly drier and better radiational
cooling. For high country, it will drop down into the 20s for most
areas, and 30s for the San Luis Valley. It will continue to clear as
the low moves further east towards sunrise tomorrow morning.
-Stewey

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 339 AM MDT Mon May 20 2024

Pattern has set up where the core of a majority of the transient
systems will pass by to the north. This track will favor the
northern half of the state with pcpn, which should spill over to the
central mts and along the Palmer Divide, but the remainder of the
area will essentially see increased wind, above normal temperatures
and primarily dry conditions.

Tuesday...First upper trough crosses the Rocky Mt region on Tue,
with the core of the low passing across WY. This is expected to be
the furthest south of any of the systems through the extended,
bringing the best chance of pcpn to much of the forecast area.
Showers and thunderstorms will be likely through the afternoon and
early evening across the central mts, Pikes Peak region and Palmer
Divide, and isolated to scattered pcpn chances for the remainder of
the area. In addition, the central mts are forecast to receive 3 to
5 inches of new snow across the higher peaks through the evening,
while SPC has painted pretty much the entire area under general
thunder. Plan on temps near seasonal normals, with 60s for the high
valleys, upper 60s to upper 70s for the plains, and near 80F for the
southeast corner.

Wednesday...The 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 afternoon and
evening showers and thunderstorms mainly over the eastern mts and
plains, with a slightly better shot for convection over the Pikes
Peak region. Temps will climb into the 60s to around 70F for the
high valleys, and 70s to near 80F for the plains.

Thursday...Another upper low crosses MT and WY on Thu, tightening
the pressure gradient across CO and increasing southwest flow across
the Four Corners. While each day through the extended has the
expectation of spotty critical fire weather conditions across the
area, Thu has the best chance for more widespread enhanced fire
danger. Since much of the fuels in the area are still in green up,
the only area for concern will be the lower elevations of the
Sangres and the Wets. Look for high temps around 70F for the high
valleys, and upper 70s to upper 80s for the plains.

Friday through Sunday...A cold front passage Thu evening will help
knock the high temps on Fri down 5 to 10 degrees from the previous
day, which will still be right around normal for this time of year.
Expect isolated afternoon and early evening convection each time,
mainly tied to the higher terrain and Pikes Peak region. Maximum
temps are forecast to be around 70F each day for the high valleys.
Across the plains, temps will warm into the 70s to near 80F on Fri,
then mid 70s to mid 80s over the weekend. Moore

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 339 AM MDT Mon May 20 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 30kts at KPUB.
There will be FROPA at KCOS around 04Z and KPUB around 05Z, 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 both
terminals. Winds will continue to weaken towards the end of the
forecast period. There is low confidence (less than 20%) for SHRA
and TSRA to be in and around the vicinity of all stations later in
the afternoon and evening today, although because confidence is low
it has been left out of the TAFs at this time. 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 for all terminals. -Stewey

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon today to 8 PM MDT this evening for
COZ225.

&&

$$

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