FXUS65 KPUB 230530

Area Forecast Discussion
National Weather Service Pueblo CO
1130 PM MDT Thu Oct 22 2020

Issued at 701 PM MDT Thu Oct 22 2020

Updated to end the Red Flag Warning that was in effect today.


.SHORT TERM...(This evening through Friday)
Issued at 701 PM MDT Thu Oct 22 2020

Main Forecast Concerns/Challenges:

1) Gusty northerly winds and blowing dust this evening

2) Patchy fog, possibly dense, near the Palmer Divide tonight and
Friday morning

3) Potential for light snow and/or freezing drizzle mainly around
the Palmer Divide late tonight into Friday morning

In the near term, cold front continues to steadily move across the
eastern plains with stronger northerly winds ushering in colder
conditions along with higher RH values. While winds remain gusty,
gusting up to around 40 kt, higher dewpoint air and RH values are
helping to improve the critical fire weather conditions which were
in place across the area for much of the day. Was able to expire and
cancel part of the Red Flag Warning earlier today, but locations
west of the I-25 corridor are still meeting criteria and have left
these areas in the Warning. The current end time by early this
evening still looks to be on track though.

The low stratus and fog discussed earlier today has remained in
place, not advancing much beyond the Palmer Divide and Kiowa county.
However, do think as we go into this evening, should see this begin
to steadily spill south with cloudy skies under lower stratus likely
for much of the plains by this evening into Friday morning. The fog
from this morning has also improved, though do have some concerns it
will redevelop later tonight as ceilings lower. Guidance not really
showing this trend though given the moist conditions already in
place and additional low level ascent and moistening expected
tonight, think its still a possibility and have maintained mention
in the grids for areas around the Palmer Divide. Low stratus and fog
Friday morning should slowly improve through the day, though veering
low level flow to a southerly direction will likely reinforce this
cloud cover.

As additional moisture arrives later tonight, moist upslope flow is
appearing to support some light precip development. Most guidance
hinting at this possibility, especially for areas around the Palmer
Divide. The moisture will likely be shallow and lack crystals,
however, additional CAA tonight will cool the column. Forecast
soundings showing some moisture in the 8-10c range later tonight and
while that is on the very low end for crystal potential, crystals
and the potential for snow will remain possible given the persistent
ascent. Don`t think it will be enough for all snow, and have
concerns for periods of either light snow or freezing drizzle. With
much colder temps tonight, surface temps will likely fall below
freezing and support some slick conditions for the Friday morning
commute. Have included this in the forecast and will increase
messaging for the potential hazardous conditions for the Friday
morning commute.

.LONG TERM...(Friday night through Thursday)
Issued at 701 PM MDT Thu Oct 22 2020

...Increasing Fire Danger on Saturday...
...Much Colder with Snow Sunday and Monday...

Friday night-Saturday...Moderate to strong west to southwest flow
aloft continues across the region through the day Saturday as the
next strong system digs across the Intermountain West. This will
keep a cool shallow airmass across the southeast plains through the
evening, with lee troughing expected to develop and deepen across
the plains through the early morning hours on Saturday. This will
allow for the stronger winds aloft to mix down and erode the cool
airmass in place through out the day. The breezy conditions will
bring increased fire danger across the area Saturday, with the
greatest concern for critical fire weather conditions expected across
the mid Arkansas River Valley, the San Luis Valley, the lee slopes
of the southeast Mts and the southern I-25 Corridor, where a Fire
Weather Watch has been issued for Saturday afternoon and early
evening. Temperatures Saturday to warm back to above seasonal levels
in the mid 60s to upper 70s across the plains, with mainly 50s and
60s across the higher terrain.

Saturday night-Monday night...Latest models continue to indicate a
drastic change in the weather through this period, as the
Intermountain West system digs across the Rockies through early
next week. The latest GFS runs have trended towards a slower and
further south and west solution of the EC, however, the latest EC
runs are indicating a further south and west splitting trough
solution, as part of the system moves across the area Sunday
through early Monday, with secondary energy digging across the
Great Basin and closes off an upper low across the Desert SW
Monday night. Despite these differences in solutions, all
solutions point to a strong arctic front moving across eastern
Colorado late Saturday night, with a much colder airmass moving
across the plains through the day Sunday. This cold airmass will
continues to push south and west across all of Colorado Sunday
night and Monday. This cold airmass, combined with moisture and
lift associated with the upper trough, will bring a period of snow
to all of south central and southeast Colorado Sunday afternoon
through Monday, with the best snow accumulations expected across
the higher terrain, especially the eastern San Juan and Sangre de
Cristo Mts, where 1 to locally 2 feet of snow may be possible
through early Tuesday morning. Snow amounts still will depend on
how the system tracks across the region, though could see 6 to 12
inches across the rest of the higher terrain, with 3 to 6 inches
possible across the high mountain valleys and portions of the
I-25 Corridor, with up to a few inches possible across the plains.
Temperatures are expected to well below seasonal levels, with
highs Sunday in the 20s and 30s across the plains likely reached
early in the morning and highs on Monday likely only in the 20s
and 30s, warmest across the high mountain valleys. Lows could be
in the single digits and teens, with any precipitation expected to
bring icy conditions on area roadways for the Monday morning commute.

Tuesday-Thursday...Drier weather and a slow warming trend remain in


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1130 PM MDT Thu Oct 22 2020

At KALS, VFR conditions are expected for the next 24 hours. Winds
are anticipated to be generally light through the forecast period
with the exception of some gusty west winds for a few hours in the
afternoon beginning around 19z.

At KCOS, MVFR conditions are anticipated to persist through about
midday Friday before ceilings begin to improve. IFR conditions have
been reported at nearby stations, so there is potential for such
conditions at KCOS into the morning. The best timeframe for IFR
conditions appears to be from about 10z through about 16z. Periods
of drizzle are also possible through the early morning hours, but
vis restrictions are not anticipated at this time.

At KPUB, MVFR ceilings are expected to persist into the morning
before improving in the afternoon. IFR ceilings cannot be completely
ruled out, but ceilings should remain in the MVFR category. Periods
of drizzle are also possible through the overnight hours, which
could reduce visibilities at times.


Fire Weather Watch from Saturday afternoon through Saturday
evening for COZ222-224-225-229-230.




NWS PUB Office Area Forecast Discussion