381
FXUS65 KPUB 091727
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
1127 AM MDT Sun Jun 9 2024

.KEY MESSAGES...

- Showers and thunderstorms are expected today, some strong to severe,
  over the mountains and adjacent plains.

- Strong thunderstorms possible Monday with the primary risk
  evolving towards slow moving heavy rain producing
  thunderstorms capable of localized flash flooding.

&&

.UPDATE...
Issued at 917 AM MDT Sun Jun 9 2024

Based off latest guidance, it appears that there will be a
better chance of precip pushing onto the I-25 corridor region
late this afternoon and early evening, and have adjusted to
forecast accordingly.

Strong storms still appear possible along and in the southern
mountains this afternoon. Past history has shown a weak tornado
or two is not out of the question, especially in the Wet Mtn
valley area - (moisture [and corresponding CAPE] are likely to
be uncharacteristically high over this region, NW flow is
is in place aloft and enhanced [channeled] SE sfc flow is
likely [favorable shear] and the EML [favorable lapse rates]
will be in place). /Hodanish

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 341 AM MDT Sun Jun 9 2024

An upper-level ridge will begin to build in today, with weakening
flow aloft that will give us an overall less active pattern than
yesterday. However, lingering moisture and instability, along with
easterly upslope at the surface, will give us another day of showers
and thunderstorms across parts of our area. Thanks to the upsloping
surface winds, most of the active weather will be tied to the
southeast mountains and the I-25 corridor. Models noticeably differ
on the amount and extent of afternoon-evening convection today,
likely due to differences in stability and mixing at the low levels.
The HRRR, which tends to be more aggressive in boundary layer
mixing, ingests more unstable air into the mountains/plains
interface and produces widespread showers and storms across southern
I-25 and Pueblo County. Meanwhile, other models such as the NAM Nest
show much more isolated convective showers, mostly tied to the
mountains with very little hitting the lower terrain. Though a good
chunk of the model output from this evening shows modest severe
parameters (700-1200 J/kg CAPE and 20-30 knots of shear) this
afternoon, stability will still be the main factor in how much QPF
the plains see. Looking through some of the ensemble members, the
majority of guidance today is keeping most of the precip over the
mountains until after sunset, after which some showers will move
east and onto I-25. Main impact concerns today will be heavy
rainfall and flash flooding, especially over more vulnerable areas,
along with gusty outflow winds and some hail.

Thanks to the cloud cover and lingering moisture, high temperatures
today will be much cooler than the previous several days, with 70s-
80s across most of the area. Later tonight, precipitation will
dissipate across the plains while still lingering in the mountains
as we move into the work week.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 341 AM MDT Sun Jun 9 2024

Remnants of the Pacific trough across the Desert Southwest will
propagate through the upper ridge across southern CO on Monday.
Showers and isolated thunderstorms will be ongoing across southern
areas in the morning.  Dew points are likely to maintain in the 50s
across the I-25 corridor and southeast plains with 40s across the
mountain valleys in the afternoon.  With afternoon
heating/increasing instability, thunderstorms will blossom again
across the mountains with a better chance of a few spilling out into
the adjacent plains during the evening before weakening as they push
eastward.  HREF mean CAPE still shows up to 1500 J/kg across the
southeast mountains and adjacent plains though deep layer shears
will be weak given light flow aloft within the remnant upper
circulation cutting through the ridge.  A strong storm or two will
be possible which could briefly support hail up to 1 inch in
diameter and wind gusts near 60 mph, but risks will transition more
towards heavy rainfall given deep layer shears 20 kts or less.  So
as organized severe thunderstorm risk decreases, risk for flash
flooding on burn scars and urban areas will increase.

Tuesday is the beginning of the drying and warming trend as the
upper trough shifts eastward and ridging returns across the
southwest U.S.  Sufficient remnant moisture lingers for scattered
afternoon thunderstorms but these will be more high based with gusty
outflow winds and brief rainfall the primary risks.

Pops continue to decrease for Wednesday and Thursday as the upper
ridge builds over the southern Rockies.  Temperatures are likely to
hit 100 across portions of the plains one or both days with 70s and
80s for the valley and mountain communities.  This will ramp up snow
melt again across the high country.

Another Pacific trough approaches the 4 corners region on Friday
spreading increasing moisture and increasing thunderstorm chances
across the mountains and plains as southerly low level flow advects
higher dew points northward into the plains. Another active day
for thunderstorms can be expected though details on storm
strengths are still to be determined. Conceptually gusty
downburst winds will be possible over the mountains/valleys and
adjacent plains where DCAPE is likely to be greatest, with
stronger storms near the KS border if southerly return flow can
bring sufficient low level moisture/CAPE northward in time.
These details will have to be resolved as we get closer to the
event, but for now Pops will increase into the scattered to
likely range for most of the area on Friday. It will dry out and
heat up again next weekend. -KT

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1122 AM MDT Sun Jun 9 2024

Main concern today will be late afternoon and evening
convection. showers and thunderstorms, with associated gusty
outflow winds, will likely impact KCOS and especially KPUB late
this afternoon and early evening. Brief periods of heavy rain
will be possible and this may bring MVFR/possibly IFR conditions
for a short period of time to KCOS and KPUB. Gusty outflow winds
will be possible, lasting an hour or so. Otherwise VFR
conditions anticipated.

For KALS, cant rule out a passing shower/-tsra later this
afternoon and early evening. Otherwise, VFR.

&&

.HYDROLOGY...
Issued at 341 AM MDT Sun Jun 9 2024

Rapid snow melt continues, leading to elevated flows along the
Arkansas River from Leadville to Avondale through at least
Monday, along with smaller creeks and streams close to the
mountains. While water levels are generally expected to stay
within their banks, fast flows can still be dangerous. Heavy
rainfall today and tomorrow could increase flash flood potential
for the southeast mountains and eastern plains, especially for
waters with already elevated flows.

&&

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

&&

$$

UPDATE...HODANISH
SHORT TERM...GARBEROGLIO
LONG TERM...KT
AVIATION...HODANISH
HYDROLOGY...GARBEROGLIO