390
FXUS65 KPUB 151030
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
430 AM MDT Sat Jun 15 2024

.KEY MESSAGES...

- There could be some patchy low clouds and fog within the San
  Luis Valley early this morning.

- Warmer today with isolated showers and thunderstorms possible
  this afternoon, developing over the mountains initially then
  moving east over portions of the plains. Showers/storms may
  produce gusty outflow winds approaching 60 mph.

- An isolated severe thunderstorm or two is possible over the
  far southeastern plains. If this occurs, it could result in
  wind gusts approaching 70 mph and hail up to quarter size.

- Hot temperatures expected Sunday and Monday with near record
  highs across the Plains.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 343 AM MDT Sat Jun 15 2024

Today...

Due to antecedent rains during the day yesterday within the San
Luis Valley, patchy near-surface low clouds and radiational fog will
be possible early this morning, especially in closer proximity to
the Rio Grande River basin.

A slow approaching major shortwave trough over the northwestern
CONUS is going to allow for an increase of mid to upper level
moisture, along with some upper level diffluence and orographic
lifting allowing for showers and thunderstorms to develop over the
higher terrain later this afternoon. These showers/storms will then
move eastward and over the plains with mid-level steering. There is
not going to be a lot of CAPE present (nearly 1000 J/kg at best),
although there will be some bulk shear of nearly 50 kts over
portions of the eastern mountains and steep lapse rates, so while I
do not have high confidence of anything becoming severe over these
mountains and over the adjacent plains/along the I-25 corridor, it
cannot be ruled out for a storm or two of becoming stronger and
possibly severe. Given the classic inverted-v profile in soundings
with high high LCLs and thus high cloud bases, as well as high DCAPE
of over 2000 J/kg for some locations of the plains, the most likely
threat will again be very strong and gusty outflow winds greater
than 50 mph, or possibly 60 mph for stronger storms. With much
higher MLCAPE values near 2000 J/kg draped across the very
southeastern corner of Baca County, and slightly better effective
bulk shear and dewpoints forecast to be in the mid 50s, I have
higher confidence of a storm or two becoming severe over this area
later in the evening. The caveat is that there are some of the high
res models are showing come CIN (convective inhibition) over the
area, which may prevent a storm from initiating. However, if it does
occur, there could be winds approaching 70 mph, as well as hail up
to quarter size in diameter.

With a strengthening upper level ridge currently present over the
region, temperatures will be warmer today, with highs topping out in
the low to mid 90s for most locations across the plains, low 80s for
the upper Arkansas River Valley and San Luis Valley, and generally
in the 50s to 70s for high country.

Tonight...

Other than a few lingering showers and storms by later in the
evening over the far eastern plains, it will become mostly clear and
dry. All showers and storms should continue to dissipate and exit
the CWA by early tomorrow morning. As skies clear, temperatures will
drop into the upper 50s to low 60s across the plains, and generally
in the 40s for high country. Depending on whether or not the San
Luis Valley gets sufficient rain, there could be low clouds and
patchy fog developing again tonight during the late night/early
morning hours if it does.   -Stewey

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 343 AM MDT Sat Jun 15 2024

There is overall good model agreement through the extended
period, with differences showing up by next Friday. Ensembles
are similar with smaller spreads through much of the week, with
spreads increasing by late week to next weekend. The main
concerns will be hot conditions Sunday into Monday across all of
southern Colorado. A cold front is expected by Tuesday
afternoon, with increased moisture and thunderstorm chances
through the end of the week.

Sunday and Monday...a longwave upper trough is forecast across
the western conus with increasing southwest flow across the
region. Downslope southwesterly flow off the mountains, and
strong high pressure to the east will help temperatures to warm
Sunday and Monday across all of southern Colorado. Highs on the
Plains will reach the upper 90s to lower 100s. Pueblo will be
within a degree or two of records (102 Sun/103 Mon), while
Colorado Springs will be shy on Sunday by a few degrees, and
close on Monday (COS records 100 on Sun/97 Mon). A few spotty
critical fire weather conditions may be possible on Sunday
across the region with large dewpoint spreads. Winds and fuel
conditions will be the limiting factors. As southwesterly flow
increases on Monday, more widespread fire weather conditions
will be present, with fuels being the limiting factor. Models
are mostly dry during this period. The exception may be areas
near the Kansas border over Prowers and Baca County, where an
isolated thunderstorm may be possible Sunday afternoon. If a
storm or two can develop, they will quickly shift eastward into
Kansas. Wind looks to be the primary risk given the high DCAPE
values and dry air in the lower levels. Overall confidence in
storm development in our area is on the lower side at this time.

Tuesday...an upper trough is forecast to pass out of the
Northern Rockies and into the Northern Plains, sending a cold
front south across eastern Colorado. Current model guidance has
the front passing by mid afternoon. This timing would allow for
the Plains to warm up in the 90s. Breezy southwesterly flow
ahead of the cold front would also allow for a period of near
critical fire weather conditions into Tuesday afternoon. Flow
behind the front will shift northeasterly by mid to late
afternoon, with cooler air filling in behind the boundary. If
the front arrives a bit sooner, temperatures will likely be a
few degrees cooler and less widespread fire weather conditions.
Moisture will also increased behind the front with a few showers
and thunderstorms possible over the Palmer Divide, spreading
southeast across the Plains Tuesday evening.

Wednesday into Saturday...the upper pattern appears to remain
persistent with broad troughing across the west and a strong
upper high to the east. Southerly flow Wednesday and Thursday
will keep moisture in place across the Plains. Daily afternoon
and evening showers and thunderstorms will be possible,
initiating over the Eastern Mountains and spreading eastward
across the Plains. Temperatures will be cool on Wednesday, with
highs mainly in the 80s across the lower elevations.
Temperatures will warm back through the 90s on Thursday. By
Friday, the upper high to the east looks to begin building
westward into the Desert Southwest turning flow westerly zonal
across Colorado. While moisture will still be present, shower
and thunderstorm chances look to decrease both Friday into
Saturday. There are model difference by this time period, mostly
dealing with how quickly the upper ridge builds into the Desert
Southwest and how quickly we dry out. Temperatures, however,
look to remain warm.  Mozley

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 343 AM MDT Sat Jun 15 2024

VFR conditions are expected to prevail for all TAF sites (KALS,
KCOS, and KPUB) throughout the forecast period. Due to recent rains
and surface-based saturation as a result at KALS, there could be
some low CIGs and radiational BR/FG this morning until sunrise, or
shortly after, which could reduce VIS to IFR and possible LIFR
criteria. Winds will be primarily influenced by diurnal effects at
all terminals. There could be VCSH/-SHRA and lower confidence of
possible VCTS/-TSRA at all stations this afternoon, mainly between
22-01Z at KALS and 00-03Z at KCOS and KPUB. If SHRA/TSRA does occur,
it could result in gusty outflow winds primarily out of the NNW at
KALS and KPUB, and SSW at KCOS and/or periodic windshifts from
variable directions and increased wind speeds for all terminals.
Depending on whether or not KALS receives rainfall again later
today, there could be low CIGS and patchy BR/FG developing again by
late tonight, towards the end of the forecast period. -Stewey

&&

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

&&

$$

SHORT TERM...STEWARD
LONG TERM...MOZLEY
AVIATION...STEWARD