Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 220528

Area Forecast Discussion
National Weather Service Pueblo CO
1128 PM MDT Mon May 21 2018

.SHORT TERM...(This evening through Tuesday)
Issued at 324 PM MDT Mon May 21 2018

Shortwave embedded in southwest flow is currently ejecting across
southern CO, firing off thunderstorms much earlier in the day vs the
past couple days. There have been a couple of embedded stronger
cells capable of producing some hail up to the size of dimes along
with brief heavy rain and gusty winds, but overall, storms have had
a difficult time maintaining strength due to weak deep layer shear.
Latest HRRR runs continue to expand precipitation eastward across
the southern plains through the afternoon and evening.  Still some
residual low level moisture out that way, with MLCAPES in SPC
mesoanalysis suggesting up to 1500 j/kg will be present.  This will
be sufficient for a strong storm or two through the evening with
hail up to dime size and wind gusts to around 45 mph the main
threats. Will have to monitor burn scars for the potential for heavy
rainfall through this evening as well. Activity will shift eastward
and diminish overnight.  The best chance for rain still looks to be
south of highway 50.

The upper low over the western U.S. will start to lift northeastward
towards the Great Basin on Tuesday with the next shortwave expected
to eject across CO ahead of the system.  Another round of isolated
to scattered afternoon thunderstorms can be expected with greatest
coverage over the mountains.  Another convergent boundary will
likely set up across the southeast plains within the surface trof
axis during the late afternoon and evening serving as another
potential focus for thunderstorm development. Dew points look a
little lower across southeast CO by afternoon.  CAPE values of up to
around 1000 j/kg and shears around 20-30 kts will lead to some
localized strong storms with small hail and gusty erratic winds the
main concerns. Doesn`t appear to be sufficient shear for much of a
severe thunderstorm risk at this time. Temperatures will continue
the upward march with highs topping out in the 80s, with 60s and 70s
for the mountain/valley communities.  -KT

.LONG TERM...(Tuesday night through Monday)
Issued at 324 PM MDT Mon May 21 2018

Tuesday night-Wednesday...Increasing southwest flow aloft continue
to be progged across the region as a broad upper trough across Great
Basin lifts north and west across the Northern Rockies. Models
continue to suggest drier air within the southwest flow mixing
across the area. This along with the breezy west to southwest winds
will lead to increasing fire danger Wednesday afternoon, especially
across the San Luis Valley where could see critical fire weather
conditions. Otherwise, isolated to scattered showers and storms
across the area Tuesday afternoon to diminish Tuesday evening, with
best chances of storms on Wednesday across the far southeast
Colorado Plains, where models are indicating a dry line developing
through the afternoon. Latest SPC Day2 outlook has this area in
marginal risk of severe storms, with large hail and strong outflow
winds the main threats. Temperatures look to warm back to above
seasonal levels, with highs Wednesday in the 80s to lower 90s
expected across the lower elevations, 60s and 70s across the higher
terrain and 40 and 50s at the peaks.

Thursday-Friday...Moderating westerly flow aloft expected across the
region as short wave ridging builds across the Rockies. Pattern
continues to support warm and mainly dry weather, with temperatures
expected to remain above late spring norms, with highs remaining in
the 80s and 90s across the lower elevations, and mainly 60s and 70s
across the higher terrain. As for precipitation, can`t totally rule
out some high based convection in the afternoon and early evening
hours, though soundings support mainly virga and gusty winds.

Saturday-Monday...Latest models indicating increasing southwest flow
aloft once again, as more Eastern Pacific energy digs into the Great
Basin, though differ on timing and location of this energy lifting
out across the Rockies. Again, pattern would suggest mainly dry and
warm conditions early in the weekend, with the potential for
critical fire weather conditions across portions of the South
Central and Southeast Colorado, along with the potential for strong
to severe storms across the far Southeast Plains later in the
weekend, with a possible dryline.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1124 PM MDT Mon May 21 2018

VFR at all taf sites overnight and through the day on Tues. Will
carry a vcts mention at KALS for a few hrs in the afternoon as mtn
convection may drift across the valley, though storms may be
fairly high based and weak. At KCOS and KPUB, likely some weak
convection over the higher terrain nearby in the afternoon, but
chance of a storm moving over either terminal is rather low. All
sites will see a period of gusty/erratic outflow winds from mid
afternoon into the evening as high based storms diminsh.




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