019
FXUS65 KPUB 202038
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
238 PM MDT Sat Jul 20 2024

.KEY MESSAGES...

- Much cooler Sunday with widespread showers and thunderstorms,
  especially over and near the higher terrain.

- Below normal temperatures continue with isolated to scattered thunderstorms
  each day, but overall trend is towards drier and warmer
  conditions towards mid to late next week.

- Another uptick in monsoon moisture possible over the mountains
  Friday and Saturday as we come under better direct
  southwesterly fetch aloft

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 226 PM MDT Sat Jul 20 2024

Current water vapor imagery and upper air analysis indicates broad
upper level ridging building across the Great Basin, with the
centroid of the system across north central Arizona at this time.
This is allowing for modest north to northwest flow aloft across
the Rockies, with GOES Blended Precipitable Water Imagery indicating
PWATS of 0.70 t0 1.15 inches (100 to 125 percent of normal) across
region at this time. Water vapor imagery is also indicating several
embedded waves sliding down the backside of the ridge across the
Intermountain West and Northern Rockies at this time.

Current forecast remains on track through the afternoon, with modest
northerly flow persisting across the Rockies, as the upper high
continues to build north and west across the Great Basin. Current
SPC meso-analysis indicates SB CAPES of 500-1000 J/kg over and near
the higher terrain, with 1000-1500 J/kg across the far southeast
Plains. Northerly surface winds across the plains at this time, will
become more east to northeast through the late afternoon, leading to
an expected slight increase in effective shears to between 25-35kts
across the I-25 Corridor and southeast Plains through the evening.
This, along with and embedded wave translating across northern
Colorado at this time, will keep scattered to numerous showers and
storms across the region through the evening with the best coverage
over and near the higher terrain. Ample moisture in place, will
allow for locally heavy rainfall and the potential for localized
flash flooding, especially for area burn scars and other flood prone
areas. Further east, with the slightly enhanced shears, there will
remain the potential for one or two stronger to severe storms,
capable of producing gusts to near 60 mph and hail around 1 inch in
diameter.

For the overnight and through the day tomorrow, the forecast becomes
more muddled, as the embedded waves bring bouts of uvv across the
region, leading to the potential for rounds of showers and storms to
continue through the late night and early morning hours. CAMs have
been inconsistent on timing and placement of these rounds of
convection, though have started to settle in on a second round
of storms moving across the Pikes Peak region around midnight, which
looks to push south and east across the southeast mountains and
plains as low level moisture and easterly upslope increases behind
another front pushing south overnight.

Cool upslope flow persists across the plains tomorrow, which looks
to limit instability on Sunday. However, NAM data does indicate
skinny cape profiles, with enough shear for strong to severe storm
potential along and west of the I-25 Corridor, if storms can fire.
Current thinking is the NAM is overdone on available moisture,
instability and its cold temperatures with MET MOS going with a high
of 66F in Pueblo on Sunday! Current forecast continues to follow the
blended forecast of scattered to numerous showers and storms, with
the best coverage over and near the higher terrain. Main threats
from storms looks to be locally heavy rainfall and gusty outflow
winds, with localized flash flooding remaining possible for the area
burn scars and other flood susceptible areas. Tomorrow continues to
be one of the coolest days of next week, with highs some 5 to 15
degrees below late July levels in the 70s to lower 80s across the
Plains, and in the 50s, 60s and 70s across the higher terrain.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 226 PM MDT Sat Jul 20 2024

Precipitable waters come down on Monday, particularly over the
mountains where values drop to around 0.5 inches during the
afternoon.  Even the southeast plains see values drop to around 0.7
to 1.0 inches by late afternoon.  We still maintain weak easterly
upslope flow at the surface and northerly flow aloft, but there
will be less forcing and even subsidence across the southeast
plains behind the departing upper trough from the night before.
Overall this should limit convective coverage some on Monday,
keeping most activity confined to in and near the mountains.
With surface dew points dropping back into the 40s to lower 50s
(highest across the far eastern plains), this limits sbCAPE to
under 700 J/kg and deep layer shears to around 20 kts. So storm
strengths should come down too with the main risk being locally
heavy rainfall over the mountains which could cause flash
flooding on burn scars or areas with susceptible/saturated soil
conditions. Otherwise, thunderstorm activity will diminish
during the late evening and overnight hours with cooler
overnight lows for some of our mountain valleys where dew points
in the 30s and clearing skies will allow for better radiational
cooling.

Northerly flow around the western U.S. upper ridge will keep
below normal temperatures through Wednesday though readings are
warming each day as pockets of drier air wrap around the upper
high and limits convection each day. There will still be
sufficient moisture for isolated to scattered thunderstorms each
day, with the greatest coverage over the mountains. But with
dew points dropping back into the 30s and 40s in the afternoons,
this will keep CAPE limited and thunderstorms more high based
with gusty winds and brief locally heavy rainfall the primary
risks.

Temperatures warm in earnest for Thursday and Friday across the
plains as the upper ridge axis shifts eastward and a lee trough
develops across the plains. This will bring a return of above
normal temperatures for both days with readings returning into
the mid to upper 90s across the plains.

Southwest flow may bring another brief influx of monsoon
moisture into the mountain areas Friday and Saturday with
another uptick in thunderstorm coverage, while southeast plains
remain on the drier and warmer side of the spectrum. -KT

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1149 AM MDT Sat Jul 20 2024

VFR conditions likely to persist over the next 24 hours
at COS, PUB and ALS. Moisture remains in place, with showers
and a few storms already developing over the higher terrain.
Showers and storms to move south to southeast through the
afternoon and evening, with good chances that all 3 terminals
seeing affects of storms through the early evening, with gusty
outflow winds and brief heavy rainfall associated with these
storms. Models continue to suggest an embedded short wave across
the Intermountain West at this time, will continue to translate
southeast across the Central Rockies through early tomorrow
morning. This will keep the potential for showers and storms
across the area through the overnight hours, with storms
possibly developing unusually early (14Z-16Z) at the terminals
Sunday morning.

&&

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

&&

$$

SHORT TERM...MW
LONG TERM...KT
AVIATION...MW