Area Forecast Discussion
Issued by NWS Pueblo, CO

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831
FXUS65 KPUB 212137
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
337 PM MDT Thu Sep 21 2017

.SHORT TERM...(This evening through Friday)
Issued at 301 PM MDT Thu Sep 21 2017

Currently...

Another hot and breezy day today. Temps were well into the 90s
across a parts of the plains as Lamar was 96F at 2 pm this
afternoon. Most other areas were in the mid 80s to lower 90s. Skies
were clear and it was breezy, with south to southwest winds in the
20 to 30 mph range. Humidities were in the 5 to 15% range across the
plains.

Higher elevations things were more reasonable with readings in the
70s in the valleys and 50s and 60s in the mtns. Skies were also
clear and it was breezy to windy.

Impressive gravity wave were clearly seen in the GOES 16 water vapor
channels.

Tonight...

temps tonight will likely be a bit warmer than last few nights as
winds across the plains should keep up, and expect 50s most areas
with a few low 60s possible across the far eastern plains. mtns and
valleys will be cool with  readings  in the 30s and 40s. Skies should
remain clear.

tomorrow...

Expect max temps to be 2-3F cooler across the plains tomorrow as
compared to today. A few more higher clouds should also be noted.
Higher RH values are likely due to a combination of slightly cooler
air and increasing RH values, especially over the far eastern plains.
Along the i-25 corridor we may reach near critical fire weather
conditions at RH values will reach down to near 15%. It will once
again be breezy to windy all areas.

As for precip, we will likely see showers and some storms over the
San Juan mtns. As for the plains, I cannot rule out an isolated
thunderstorms over the far southeast plains, but if it happens, it
will be late and likely over Baca county. Storms, if they develop,
have the potential to become strong. Over the remainder of the area
it should be dry tomorrow.

.LONG TERM...(Friday night through Thursday)
Issued at 301 PM MDT Thu Sep 21 2017

Models in good agreement for the first half of the extended period
with model differences and run to run inconsistencies into the
middle of next week. The potential for severe weather exists this
weekend, and cooler, wet weather into early next week.

Friday night through Sunday...a strong upper level storm system
over the intermountain west will slowly track east into Colorado
by Sunday. This will set the stage for the potential for severe
weather across Southern Colorado through the weekend.

Expect showers and thunderstorms to be ongoing along the
Continental Divide Friday evening and continue through the
overnight hours. Snow levels look to remain high over the
mountains, with an inch or two possible above 11000 feet. Models
have been in good agreement with a dryline developing by Friday
afternoon and isolated strong, to possibly severe storms
developing near the Kansas border during the late afternoon or
evening hours. This activity will slowly shift east into Kansas
during the overnight hours. It should be noted that models are
less excited about the severe weather threat, or develop
thunderstorms too far east. CAPE values are only modest and shear
will be increasing through the overnight hours. Large hail and
damaging winds would be the threats out east.

A more dynamic setup is expected on Saturday across eastern
Colorado in regards to the potential for severe weather. The upper
low over Utah will continue to slowly track east. An upper
disturbance over the Desert Southwest is forecast to eject
northeast across Colorado by Saturday evening. Continued showers
and thunderstorms are expected over the Mountains, and should
expand in coverage throughout the day. Over the Plains, a dryline
is forecast to develop by early afternoon. CAPE values will be
running a bit higher, and shear is expected to be quite strong
with the upper disturbance ejecting across the area. Severe
weather is expected, main east of a La Junta, to Branson line.
Large hail, lightning, and even perhaps a tornado will be possible
across the far Eastern Plains. In addition, very heavy rainfall
will be possible, and flash flooding will be a threat over the
Plains. Expect stronger storms to lift northeast into Kansas
through the overnight hours, with more scattered, weaker activity
spreading east across the region through Sunday morning. Snow
levels will look to lower to around 9000 feet Saturday night with
a few inches possible, especially along the Continental Divide.

Sunday also has the potential to see severe weather across the
Plains. Much will depend on a cold front. Current model
projections develop a surface low across the Plains, with a cold
front dropping south along the I-25 corridor. This will set up a
boundary over the eastern Plains, roughly from Kiowa County,
southwest toward Trinidad. Areas ahead of this boundary will see
the greatest potential for strong to severe storms. If the
surface low moves more quickly eastward, the front will push
southward and limit the severe weather potential. As of now,
there is much uncertainty in where the finer details will develop.
The front will push south Sunday night with light precipitation
filling in behind, as the upper begins to lift across Colorado.
Snow levels will continue to fall, withe some guidance suggesting
to around 7500 feet. Temperatures will fall throughout the weekend
with 70s on Saturday, falling into the 60s to 70s on Sunday.

Monday through Tuesday...the upper system is forecast to split and
sag across Colorado early in the week. This will keep easterly low
level upslope and cool temperatures across the region early next
week. Snow levels will remain lower, generally above 8000 feet.
Temperatures will struggle to get out of the 50s to mid 60s. How
much precipitation the Plains receive will depend on moisture and
upslope flow.

Wednesday and Thursday...models differ on the split, with the GFS
having a stronger system developing over the Desert Southwest
sending disturbances north across Colorado with continued showers
and thunderstorms. The ECMWF is a bit slower and not quite as
strong with this system and keeps southern Colorado on the drier
side. Cooler temperatures will likely prevail with 60s and 70s
across the lower elevations.  Mozley

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 301 PM MDT Thu Sep 21 2017

VFR conditions are anticipated during the next 24 hours at all 3 taf
sites; KPUB, KALS and KCOS.

Gusty southwest winds will occur at all 3 taf sites the rest of this
afternoon and early evening. Winds will decrease later this evening
but will pick up from the south-southwest again tomorrow
afternoon.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 7 PM MDT this evening for COZ226>237.

&&

$$

SHORT TERM...HODANISH
LONG TERM...MOZLEY
AVIATION...HODANISH



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