Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 212152

Area Forecast Discussion
National Weather Service Pueblo CO
352 PM MDT Fri Jul 21 2017

.SHORT TERM...(This evening through Saturday)
Issued at 352 PM MDT Fri Jul 21 2017

...Thunderstorm chances increase next 24 hours...

Monsoon plume continues to stream up across the Four Corners region
and across the northern portions of CO today.  Appears to be an MCV
embedded within the plume across western CO.  This feature will lift
slowly north northeastward through tonight.  Storms fired early
(around 16Z) across the western mountains and will continue to
increase in coverage and expand eastward through the afternoon
across the mountains and northern portions of the CWA.  Models
continue to hit the Central mountains of Chaffee and Lake counties
as well as the Pikes peak region the hardest this afternoon with the
most widespread thunderstorm activity.  Locally heavy rainfall
capable of producing flash flooding will be possible over these
areas, particularly where the ground is susceptible such as burn
scars, urban areas, and the Chalk Cliffs west of Buena Vista.  So
those areas will need the closest monitoring.  Meanwhile diffuse
frontal boundary will set up along the Palmer Divide this afternoon
where CAPE values of around 1000 J/kg will be possible.  Soundings
display more of an inverted V profile across most of southeast CO so
think gusty wind potential will be highest across northern portions
of the plains today as outflow boundaries reinforce surging front.
In fact MSLP gradient still looks pretty strong late this afternoon
and evening across Pueblo and El Paso counties behind the front.
Gusts on the order of 40 to 50 mph would not be out of the question
given the scenario.  Have played up winds a bit more from inherited
grids, but overall forecast looks on track.

Will keep scattered showers and isolated thunderstorms going through
the night across the mountains where embedded disturbances within
the monsoon plume should keep things active. Although threat for
flash flooding will decrease significantly after midnight, burn
scars will need to be monitored closely, particularly Hayden and

Should be an early start to an active day on Saturday as remnant MCV
will continue to slowly drift eastward across the area.
Thunderstorms will fire over the mountains during the morning...then
spread off into the adjacent plains during the afternoon.  GFS and
NAM still focus the most widespread thunderstorm developing mainly
south of highway 50.  However with upslope flow, suspect surface dew
points will stay in the 50s to near 60 across the plains and
soundings do not look overly capped.  Will place at least scattered
showers and thunderstorms across all of the plains tomorrow with
likely pops across the southern I-25 corridor/Raton Ridge region.
Southeast mountains will be particularly vulnerable tomorrow to
heavy rainfall and flash flooding.  Later shifts may need to
consider a flash flood watch for these areas. It almost goes without
saying burn scars will be particularly vulnerable.  -KT

.LONG TERM...(Saturday night through Friday)
Issued at 352 PM MDT Fri Jul 21 2017

Not many adjustments required from previous meteorological
reasoning as active meteorological conditions at times are
anticipated over many sections of the CWFA, primarily from
Saturday evening into Sunday night and then again from later
Wednesday into Friday.

Main meteorological concerns continue to include but are not
limited to temperatures, enhanced precipitation potential/locally
heavy rain and localized flash flooding potential. In addition,
the highest potential for intense thunderstorms at times exists
from this weekend and then again from Wednesday into next Friday.

Latest longer term PV analysis, computer simulations and forecast
model soundings still indicate that projected precipitable water
values over many portions of the Interstate 25 corridor should run
around 1 inch or slightly higher at times this weekend and then
again by later next weekend.

Once again, the combination of subtle upper disturbances, adequate
atmospheric moisture, surface boundaries and the daily orographic
heating cycle will be capable of producing enhanced precipitation
chances(including flash flooding potential at times) this weekend
and then again by later next week.

Recent projections still indicate that localized capes and
LI`s nearing/exceeding 1000 J/KG and -5C respectively at times
this weekend and then again from Wednesday into next Friday will
allow for some intense thunderstorm development. Once again,
basically continued low-grade mean-layer wind shears will help to
limit the intensity of these storms. WFO Pueblo will monitor
closely and issue hydro/severe products if/as needed.

Regarding temperatures, longer term maximum temperatures are
expected to run within a category or so of late July
climatological averages, while projected minimum temperatures
during the longer term should remain above late July
climatological averages over the majority of the forecast
district. Finally, generally low-grade gradient are projected to
continue over the forecast district from Saturday night into next


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 352 PM MDT Fri Jul 21 2017

While conditions will remain mostly VFR at the TAF sites, Scattered
to numerous showers and thunderstorms over the mountains will result
in considerable Mtn top obscurations at times with MVFR to IFR
conditions at times across the higher terrain.  KALS and KCOS will
see the greatest chance for a thunderstorm through this evening and
will carry a tempo group in the KCOS TAF site.  A little less
certainty exists for KALS so VCTS will suffice for now.  The main
threat with thunderstorms today at the terminals will be gusty
outflow winds up to 40-45 kts.  Locally heavy rainfall will also be
a threat should a stronger cell impact the terminals.  KPUB will see
less of a threat, however thunderstorm outflows will reinforce winds
behind a cold front bringing a gusty wind shift into the KPUB area
around 01Z.  Gusts to 40-45 kts will be possible with VCTS possible
along and behind the boundary as it moves through. Thunderstorms
should end around 06z for the TAF sites, though VCSH within the
active monsoon plume may continue into the overnight hours for





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