Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 192112

Area Forecast Discussion
National Weather Service Pueblo CO
312 PM MDT Sat May 19 2018

.SHORT TERM...(This evening through Sunday)
Issued at 247 PM MDT Sat May 19 2018

Upper low will continue to lift off to the northeast with trailing
wave firing off showers/thunderstorms across the mountains moving
across during the evening.  Best instability resides along the
southeast mountains and across the far southern plains bordering New
Mexico.  MLCape showing up to 1000 j/kg down that with shears
running around 35-40 kts.  Las Animas and Baca counties are
outlooked for marginal severe...though the slight risk area hugs the
border just to the south.  This area will be the primary area to
watch for the potential for large hail and damaging winds later this
afternoon through this evening. Across the remainder of the plains,
nice cap in place with cool stable surface airmass, particularly
across northern portions of the plains.  Dew points are actually
drying out a bit as well.  So, though latest HRRR runs continue to
spread convection eastward onto the plains, suspect it will weaken
as it hits the cooler more stable airmass to the east.  Best chance
for marginally severe hail will be across the eastern slopes of the
southeast mountains.  Could also be looking at a localized flash
flood threat for burn scars like Junkins or Hayden should a stronger
storm impact these areas.

Convection should decrease pretty quickly this evening as lower
levels stabilize.  Another round of stratus will develop across the
plains tonight, especially toward early morning for the Pikes Peak
region as low level winds shift around from the southeast.

For Sunday, another round of afternoon showers and thunderstorms can
be expected as another shortwave embedded in southwest flow aloft
moves across the area.  Still looking at around 500 to a little less
than 1000 j/kg of CAPE across the southeast mountains during the
afternoon, with deep layer shears looking a little weaker, on the
order of 25-35 kts. Main focus for thunderstorms will be across the
central mountains according to NAM and GFS. Plains will stay largely
capped, but could see a storm or two drift off into the adjacent I-
25 corridor during the late afternoon/early evening. Main concern
with thunderstorms will be small hail and the potential for locally
heavy rainfall on the more susceptible burn scars. -KT

.LONG TERM...(Sunday night through Saturday)
Issued at 247 PM MDT Sat May 19 2018

...May Showers and Thunderstorms will Continue...

The weather pattern will continue to support more typical May
weather for the next several days.  Southern Colorado will remain
under a moist and unstable pattern through Tuesday with daily rounds
of afternoon and evening showers and thunderstorms.  Models keep the
region under moist, southwest flow with embedded disturbances
helping to trigger convection.  One such disturbance will track
across the region Sunday afternoon, coincidental with peak heating,
to produce another round of showers and storms lasting into the
evening.  As typical, convection will tend to initiate over the
mountains first and then work east across the plains.  It does look
like the convection should hold together pretty well as it comes
across the I-25 corridor, so should be another round of showers and
embedded thunderstorms for most along the corridor. Right now, it
looks like convection will favor the northern half of the
corridor, including the Canon City, Pueblo and Colorado Springs
areas. Primary storm hazards will be lightning, small hail, 40 mph
winds and locally heavy rain.

Another disturbance will try to make it up into the area Monday
afternoon and evening.  it currently looks like this will favor more
southern areas as the bulk of the disturbance remains over New
Mexico.  However, with the moisture that remains, it should be
enough for another round of showers and storms.  This time
convection will favor more southern parts of the region, including
the southern mountains and southern I-25 corridor.  The primary
storm hazards will be similar to those on Sunday.

A third disturbance will track from southwest to northeast across
the area Tuesday afternoon and evening, bringing more showers and
storms.  This looks like the last disturbance before a break in the
action occurs Wednesday into Thursday.  During this time, a period
of warmer, drier westerly flow will set up across the region,
limiting precipitation chances and elevating the fire danger.  It is
unclear at this time how high the fire danger will go.  Will the
recent showers combined with more showers over the next few days
moisten and green things up enough to keep the fire danger down?
We`ll have to wait and see.

Then, after a brief dry spell, things trend wetter and more
unsettled again, possibly as early as Thursday evening over northern
parts of the forecast area but more likely Friday and Saturday over
the entire area.  If recent model trends continue, Saturday will be
the wettest day with the best precipitation chances.


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 247 PM MDT Sat May 19 2018

Isolated to scattered thunderstorms will continue over the mountains
and southern border areas of the southeast plains through this
evening with MVFR Cigs/vis.  Thunderstorms should decrease in
strength as they drift eastward into cooler more stable conditions
across the plains.  Strongest storm potential will be across the
border counties of Las Animas and Baca counties.  Most thunderstorms
will diminish by this evening with MVFR cigs redeveloping across the
I-25 corridor affecting the KCOS and KPUB terminals overnight.

Southwest winds at KALS will remain gusty through 00z before
shifting from the east during the evening. Low level moisture will
increase tonight which elevates concerns for fog development towards
morning however model soundings and guidance do not support this.
Will not include fog in the TAF for now as it looks like a very low
probability occurrence. -KT




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