Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 132108

Area Forecast Discussion
National Weather Service Pueblo CO
308 PM MDT Thu May 13 2021

.SHORT TERM...(This evening through Friday)
Issued at 304 PM MDT Thu May 13 2021

...A severe storm or two is possible tomorrow...


Partly cloudy skies prevailed across the mtns while it was mostly
clear across the plains. Temps at 2 pm were in the 60s to L70s
across the plains and larger valleys with mainly 40s and 50s in the
mtns. A weak trough was noted over NE CO extending into NE, and a
few -tsra were trying to build along this boundary. It was rather
moist in the low levels and dewpts continued in the 40s to around
50F over the plains. A theta-e max was noted over the eastern
sections of the Palmer Divide.

Rest of this afternoon...

Trough axis will continue to drop southeast over the Central Great
Plains and this will likely initiate some convection as it moves
southeast. Some echoes were noted over EC CO and I cannot rule out a
weak storm moving over eastern Kiowa county and have put in some low
pops over this area during the remainder of this afternoon.

Another area which we may see an isolated -tsra will be over the
southern Sangres/Raton Mesa region.

For tonight..

Expect any isolated precip which develops will will come to an end
with decreasing insolation.

Low temps tonight will fall into the M40s across the plains with 30s
and 40s in the larger valleys. 30s mainly in the mtns. I cannot rule
out some locally patchy fog as RHs will remain relatively high, but
expect any fog to be relatively isolated.


A weak boundary will drop down early tomorrow morning bringing a
brief period of northerly winds before winds switch around to an
upslope direction over the plains. This will bring increasing low
level moisture to the region. Temps aloft are relatively cool and
mid level flow is modest. A stout EML (Elevated Mixed Layer) is also
noted. This will allow sufficient instability to develop, and with
bulk shear of ~40 knots, we will likely see the potential for one or
two severe storms to develop. Best chance of storm development will
be over the Pikes Peak region by mid afternoon with the storms
dropping southeast during the rest of the afternoon. Other storms
will be possible over the eastern mtns and over the plains, but
activity should be rather isolated.

It will feel likely May tomorrow with max temps reaching into the
L80s most of the plains; 70s over the larger valleys.

.LONG TERM...(Friday night through Thursday)
Issued at 304 PM MDT Thu May 13 2021

...Heavy Rain and Strong/Severe Thunderstorms Possible Next Few

Saturday... Starting the long term period, an upper level ridge will
be the main synoptic influence over the area, with small
disturbances/vorticity maximums propagating within the flow aloft,
which will aid in synoptic level lift. At the surface, a weak lee
cyclone looks to develop over the far southeastern portions of the
CWA Saturday. This feature will aid in surface flow becoming more
easterly throughout the day. Given the easterly flow, dewpoint
values of high 40s to low 50s will advect into the region. The
surface flow will also allow for orographic forcing to become
prominent over the eastern mountains and Palmer Divide, which will
force thunderstorm initiation over those areas. Given the increased
moisture, bulk shear values of 30-40 kts, and mixed-layer CAPE of
1200+ j/kg, thunderstorms will likely become organized enough to be
severe as they propagate eastward off the mountains and into a
better environment; some supercell structures are possible given the
shear in place. The greatest concern at this time would be large
hail and gusty winds. Strong microburst also seem possible given
DCAPE values of 1000+. Over other parts of the CWA, expect the
possibility of rain showers and thunderstorms during the afternoon,
especially over the mountains, as weak westerly flow aloft aids in
orographic lift in those areas.

Sunday...The aforementioned ridge will continue its trek eastward,
but a small upper level disturbance will pass over the forecast area
which will aid in weak synoptic level ascent. At the surface,
easterly flow will continue to be present and will aid in more
moisture advection, with dewpoints again in the high 40s and low
50s. Again, orographic lift looks to be the main forcing mechanism,
which will cause thunderstorms to initiate over the eastern
mountains. With increased dewpoints, mixed-layer CAPE values of
1500+ j/kg, bulk shear around 30 kts, strong to severe storms still
look possible over the eastern plains as thunderstorms move off the
mountains and tap into the better environment. Elsewhere over the
CWA, again expect the possibility of heavy rain showers and
thunderstorms during the afternoon, as at least some modest levels
of instability spread past the eastern mountains.

Monday - Thursday... An unsettled weather pattern will continue over
the forecast area through the work week. Operational and ensemble
models are in good agreement with digging the closed low further
southeastward throughout the early parts of the week, with another
trough following immediately behind that. Given the slow moving
systems with increased synoptic lifting, easterly flow at the
surface, dewpoints still within the upper 40s+, and instability over
the CWA, periods of heavy stratiform rains and thunderstorms look
likely. The GEFS and EPS ensembles models are showing QPF values of
over 0.5 inch CWA wide, and given the continued presence of decent
moisture over the area and continued support at the surface and
aloft, this scenario doesn`t seem out of the realm of possibilities.
These rains would be beneficial to the drought stricken areas of
Colorado, but may pose a flooding risk, especially over burn scars,
if areas of training rains were to develop.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 304 PM MDT Thu May 13 2021

VFR conditions are anticipated during the next 24 hours at all 3 taf
sites, KPUB, KALS and KCOS. The only concern will be over KCOS and
KPUB were there will be a chance of a thunderstorm tomorrow
afternoon which will have the potential to cause gusty winds and
brief periods of low cigs/vis do to clouds and rain.




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