Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 291015

Area Forecast Discussion
National Weather Service Pueblo CO
415 AM MDT Mon May 29 2017

.SHORT TERM...(Today and tonight)
Issued at 357 AM MDT Mon May 29 2017

Weak cold front dropping south through the plains early this
morning, as latest in a series of short waves rotates southwestward
around the Great Lakes upper trough. Surface high pressure will
gradually build south through the plains today behind the front,
with surface winds becoming weak easterly along and east of the
mountains by afternoon. Combination of weak upslope/modest
instability and subtle upward motion from approaching upper wave
will lead to an upturn in convective chances today/tonight, although
low level moisture return is rather un-impressive, as surface
dewpoints only climb back into the 30s and 40s over the plains,
leading to CAPES in the 400-800 J/KG range by late afternoon. Can`t
rule out a stronger storm or two as convection pushes away from the
mountains, but severe threat looks rather low given weak instability
and marginal shear. Activity then pushes southeastward across the
plains during the evening, ending in most locations by around
midnight. Max temps today look fairly similar to Sunday, with highs
in the 70s on the plains and 50s/60s mountains and interior valleys.

.LONG TERM...(Tuesday through Sunday)
Issued at 357 AM MDT Mon May 29 2017

Low confidence forecast through the extended period with high
uncertainty in the pattern evolution. For the most part we will be
in an active pattern, and showers and thunderstorms will be highly
dependent on disturbances drifting across Colorado.

Tuesday through Thursday...have the highest confidence during this
period with active weather across the region. An upper ridge will
slowly move across the Rockies while an upper trough drifts from
off the northern Baja coast, and across the Desert Southwest.
Abundant moisture along with southeasterly upslope flow is
forecast to remain across Colorado and showers and thunderstorms
are expected each afternoon and evening. Initial development is
forecast over the mountains, with thunderstorms shifting east
across the Plains during the evening hours, and dissipating as
they track east across the far Eastern Plains. Threats from
thunderstorms include small hail, gusty outflow winds and locally
heavy rainfall. If stronger storms move over area burn scars,
there could be increased threats of flash flooding. At this time,
weak shear and modest instability should prevent any storms from
becoming severe.

Friday through Monday...the upper pattern becomes much more
difficult through the later half of the extended forecast. The
upper ridge is forecast to shift east, while several shortwave
troughs will move across the west. Exactly when these
disturbances will impact Colorado and how strong they will be key
in where precipitation chances will be greatest. For now, it looks
like there will be decent chances for showers and thunderstorms
Friday through Sunday, with potentially lesser chances early next
week. There are big differences between the ECMWF and GFS, and
ensemble spreads are quite large, this leading to the uncertainty
in the forecast. Just know that there will likely be periods of
showers and thunderstorms, with limited severe threat at this
time, and along with elevated chances for flash flooding on area
burn scars should heavier cells move over them. Mozley


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 357 AM MDT Mon May 29 2017

VFR at all taf sites today and tonight. Mountain convection will
develop 18z-21z, then drift onto the plains/I-25 corridor 21z-02z.
Will include VCTS at KPUB and KCOS late this afternoon into the
evening, with brief period of MVFR cigs/vis under a few of the
stronger storms. Lower chance of a tsra at KALS and will leave any
thunderstorm mention out of the taf at this point.




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