Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 302029

Area Forecast Discussion
National Weather Service Pueblo CO
229 PM MDT MON MAY 30 2016

.SHORT TERM...(This evening through Tuesday)
Issued at 227 PM MDT Mon May 30 2016

...Increased potential for thunderstorms for the SE Mts/Adjacent
Plains Tuesday...

Forecast area will be under weak forcing today ahead of trough axis
out west connecting northern stream upper low moving through through
northern U.S. Rockies and the desert southwest upper low.  Showers
and thunderstorms have fired off over the mountains...and are
progged by models to continue eastward across the plains through the
late afternoon/early evening.  Surface low centered just north of
KLHX has kept winds more southerly to southwesterly across the
southern I-25 corridor and southern plains, and HRRR seems more
inclined to mix out low level moisture today vs yesterday. However,
where southeasterly winds maintain...could still see some lower 50
dew points...and CAPE values near 2000 J/kg through the early
afternoon until mixing drops these off during the evening.  Weak mid
level winds today suggest deep layer shear may be on the weak side
for organized supercell thunderstorms...but certainly a strong to
marginally severe thunderstorm or two will be possible across the
southeast plains to the east of KLHX.  Main threat will be gusty
winds to around 60 mph...but some hail up to 1 inch in diameter will
also be possible with any initial intense updrafts.  Activity will
shift eastward into KS overnight.

Northern stream upper Low will move eastward into the Dakotas
tonight sending a cold front through southeast Colorado.  Initially
wind shift looks more thunderstorm outflow dominated this
evening...but a secondary surge is expected after 09z with the main
front.  This will push cooler air into SE CO for Tuesday with winds
shifting around from an easterly upslope direction during the
afternoon. Question for Tuesday will be how much low level moisture
will be retained behind the front and how much instability will be
present. One of two scenarios could play out.  If dew points drop
off into the lower 40s this will significantly cut back on CAPE
across the plains, but would likely maintain a narrow ribbon of up
to 1000 J/kg of CAPE over the southeast mountains.  However if
surface dew points can maintain in the upper 40s and 50s...then this
may be enough to keep 1000-1500+ J/kg of CAPE across much of the
southeast plains.   Still looks like main threat will be for
widespread showers and thunderstorms for the southeast mountains
initially during the afternoon with the plains being capped.  . Best
chance for a few strong storms or two will be over the mountains,
particularly south of highway 50. This area is most likely to remain
under low level theta-e axis with southern border counties also
having some potential for some strong to marginally severe
thunderstorm development in the afternoon. Will have to watch the
burn scars in the SE mountains tomorrow afternoon as heavy rainfall
from thunderstorms could produce some localized flash flooding for
these more flood prone areas. For now think the risk is too
localized to warrant flash flood watches at this point, but this
will be re-assessed as the time frame gets resolved by higher res
models. Snow levels will remain rather high through the day
tomorrow, most likely above 11.5kft with higher peaks picking up a
quick couple inches of snow during the afternoon. -KT

.LONG TERM...(Tuesday night through Monday)
Issued at 227 PM MDT Mon May 30 2016

...Heavy Rain Possible Tue Night...

Main concern in the extended comes early...Tue night...then things
gradually settle down as a high amplitude ridge begins to build over
the Rockies.

Tue night...we get a good shot of upslope over the Ern CO Plains, as
a 1020 ridge builds Over the High Plains on the backside of a
shortwave system moving through the Dakotas and southern Canada.
Concurrently...a weak low pressure system will track through
southern AZ and NM. This will create a favorable upslope regime for
our eastern mountains and I-25 corridor. NCEP models are in good
agreement with between 0.5 and 1.0 inch of QPF over this region Tue
night into Wed morning. Intensity level will be waning, so flash
flood threat looks limited. However, still the possibility of some
heavier cells impacting urban zones and burn scars, so will have to
keep an eye on trend through the night into Wed morning. Heaviest
amounts will be over Pikes Peak area and Wet mountains. Have
boosted POPs to categorical for these zones, and spread POPs a bit
farther to the east. Most of the I-25 corridor should see wetting
rains. Far eastern Plains a bit more in question, but at least a
chance of some rain for the areas farther east. For the mountains,
snow levels may get down to 10000 feet or so, but heaviest snow
accums will be above 11000 feet. Currently have about 4-8 inches of
snow for the summit of Pikes Peak, and 3-6 for the Wets and Sangres.
Considered an advisory for these high elevation zones, but given the
high snow levels and relatively brief window of opportunity for
higher QPF, will hold off. Travelers to the high country should be
prepared for winter conditions through early Wed.

Should see a bit of a respite late Wed morning into early afternoon,
before another round of showers and a few storms hits Wed afternoon
and eve, with persistent but weakening upslope through Wed night.
This round does not look as heavy or widespread as the earlier one,
however. After Wed, the upper ridge begins to build strongly over
the Central Rockies, and temps will be on the increase over our
area. Could see temps approach 90 degrees for the plains by the
latter part of the week. Some moisture trapped under the ridge will
keep a daily threat of showers and storms going each afternoon and
eve, but primarily over the higher terrain and surrounding areas.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 227 PM MDT Mon May 30 2016

Isolated to scattered showers and thunderstorms will continue to
spread eastward across the plains this evening.  Main threat with
thunderstorms will be gusty erratic winds to around 40-50kts.  CIGS
will remain VFR...though could briefly drop into the MVFR category
under the stronger storms.  This is most likely to occur to the east
of KLHX through the evening.  Thunderstorms should diminish for most
areas by 03z.  Winds will shift around from the north, and increase
to 15-25 kts early Tuesday morning as a front moves through.  This
will bring in MVFR to local IFR CIGS for the Palmer Divide region
which could spread into the KCOS area early Monday morning. For now
think that northerly downslope winds off the Palmer should keep
stratus to the north of the taf site. There will be a better chance
for -SHRA/-TSRA at KCOS and KPUB tomorrow afternoon and evening with
CIGS dropping into the IFR category Tuesday evening. KALS should
feel little affect from this front on Tuesday with isolated -TSRA
possible during the afternoon. -KT


.PUB Watches/Warnings/Advisories...


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