Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 131011
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
411 AM MDT Sun Aug 13 2017

.SHORT TERM...(Today and tonight)
Issued at 411 AM MDT Sun Aug 13 2017

...Severe thunderstorm likely on the far eastern plains later
today...

Currently...

Weak shortwave moving across the far eastern plains early this
morning. A cluster of thunderstorms was still ongoing at 3 am across
Baca county. Otherwise, it was dry across the region. Temps were in
the 60s across the far eastern plains, 50s across the lower Pike
Peak region and valleys and 30s and 40s in the mountains. The
coldest temps were across the central mountains where readings at
mtn top were near freezing. Dwpts on the plains were in the 60s
across the far se plains and 50s across the rest of the plains. A
weak sfc trough existed from Burlington to Las Animas to Kim.

on the large scale, a short wave was noted over the ID/NV/UT region.

Today...

Lots of CAPE will be in place over the eastern plains today,
especially the far eastern plains. Guidance ranged from 2500 to 3500
J/KG. These are some rather impressive numbers for the plains of
Colorado. Deep shear is in place as a 70 knt jet will be located
over the southern tier of the state this afternoon, and this will
allow for bulk shear values to range in the 35-45knt range across
most of the plains. A short wave will be moving through the area
during prime heating. The main missing ingredient for well organized
rotating storms today is that the lower level winds are forecast to
be weak, so the potential for significant low level mesocyclone
development is rather low. This is indicated in the latest SPC
tornado probabilities as values in the risk area are less than 2%.
Additionally, helicity track products from the hi reso guidance are
not to gung-ho on showing well defined tracks with storms.
Nonetheless, lots of CAPE will likely lead to some big hail reports
across the far eastern plains today, and SPC has the far eastern
plains "hatched" for hail.

Although classic ingredients are not being indicated in the guidance
for significant low level mesocyclones, I do have a couple of
concerns. The first is the potential for non-supercell tornado
development may be higher than normal as there will be a well
defined boundary over the far eastern plains associated with the sfc
trough. Past severe weather events have shown the potential exist
for getting several non supercell tornadoes developing along these
sfc boundaries. Secondly, "big CAPE days" can allow for storms to
locally enhance the near storm environment, which could allow for
the lower level winds to be stronger than what guidance indicates.

As for timing, latest guidance is showing the best forcing coming
out during prime heating (mid afternoon to early evening), so things
are going to be ripe for severe convection later today.

Tonight...

Convection will likely be primarily over the far eastern plains by
this evening with little or no storms over the mtns/I-25 corridor
region. Storms should clear the entire region by midnight (or
earlier).


.LONG TERM...(Monday through Saturday)
Issued at 411 AM MDT Sun Aug 13 2017

.Monday...Trough builds into the Great Basin with southwest flow
aloft ahead of the trough. GFS and EC hint at a weak disturbance
moving into the region helping to fire diurnal convection over
the mountains. Further east, weak lee trough will develop with
the deeper moisture being in the far eastern Colorado counties
and into Kansas. Models show over around 1500 J/kg near the
Kansas border, but bufkit soundings suggest atmosphere will be
capped. Still will be some convection over the plains, but with
weak shear and cap do not anticipate any strong to severe
convection at this time. Warming trend continues with highs around
90 on the plains.

.Tuesday...The trough over the Great Basin moves over eastern
Colorado sometime in the afternoon or evening. With the lee trough
near the Kansas border, there is the potential for some stronger
to severe storms over the eastern plains. SPC day 3 outlook has a
marginal risk covering much of the eastern plains from roughly La
Junta and to the east. Main factor for stronger storms will be
where the lee trough sets up. The the west of the lee trough,
drier lower levels will preclude much severe weather. Further
west, location and timing of the trough will determine when
convection develops. Drier mid level air will advect into the
region some the southwest which would limit diurnal convection
over the mountains.

.Wednesday through Saturday...Another trough moves over the region
from the west on Wednesday with drier mid level air continuing to
move into the region. The drier air will reduce convective
coverage over the mountains. Further east, the model hint that
some low level upslope will develop behind the trough which
departed the region Tuesday night. Currently looks as if the
atmosphere on the plains will not be very unstable as low level
moisture is slow to return behind the front. Starting Thursday,
northwest flow develops over the region. Will have to watch for
increasing lower level moisture on the plains with upslope flow
developing and for disturbances helping aid in the development of
convection. Tough to get too specific in timing of events and
followed the superblend closely. Much cooler air will stay to the
north and east of the region with temperatures generally near
normal. --PGW--

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 411 AM MDT Sun Aug 13 2017

Showers and storms will be possible over the KCOS region by as early
as 20 UTC and lasting until about 24 UTC. KPUB may also see some
storms during this time period but the probability will be less.
Isolated storms will be possible in the San Luis valley (KALS) this
afternoon and early evening. Otherwise expect VFR conditions at all
3 taf sites.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...HODANISH
LONG TERM...PGW
AVIATION...HODANISH



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