139
FXUS65 KPUB 182324
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
524 PM MDT Wed Sep 18 2024

.KEY MESSAGES...

- Dry and generally quiet Today and Thursday. Frost will be
  possible in the San Luis Valley Tonight.

- Medium to high (50-60%) confidence in a storm system impacting the
  region during the weekend.

- Weekend storm system will bring increased precipitation
  chances, with chances for severe weather across the plains.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 235 PM MDT Wed Sep 18 2024

Dry southwest flow will remain in place across the area today as an
upper-low digs down over the west coast. High temperatures this
afternoon will be slightly above normal, with high-80s to low-90s
over the plains. Otherwise, things will be dry and quiet weather-
wise aside from some gusty winds.

Tonight, conditions will be quiet, but strong radiational cooling
over the San Luis Valley will drop temperatures close to freezing,
resulting in some potential frost that could damage vulnerable
vegetation. Otherwise, temps over the plains will sit in the 40s-50s
tonight.

For Thursday, this pattern largely continues. High temperatures will
be in the 80s across the plains and in the 70s over the valleys.
Surface winds will generally be diurnally-driven and a bit less
gusty than today. Skies will remain mostly clear and conditions are
expected to be dry. Though humidities will be in the teens across
the plains, winds should stay light enough to avoid any major fire
weather concerns.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 235 PM MDT Wed Sep 18 2024

Thursday Night: Thursday evening and night will bring quiet weather
to south central and southeastern Colorado. Southwest flow will
develop ahead of an approaching system to the west. While orographic
forcing will be ongoing, dry air and stable air will limit any
precipitation development, with dry conditions expected for the
region. Otherwise light winds and mostly clear skies are
anticipated. Focusing on temperatures, a mild to cool night is
expected. Light, but occasionally downsloping winds will help keep
the area around seasonal low temperatures.

Friday: For the end of the weekend, active weather starts to make a
return. Southwest flow will continue over south central and
southeastern Colorado ahead of a closed low to the west of the
region. While stronger forcing will remain to the west, synoptic and
orographic forcing will increase over the area. Along with that,
moisture will start to increase ahead of this system, particularly
over the far southeastern plains. With that all said, dry conditions
are anticipated for most still, though isolated high based
thunderstorms are expected across the far southeastern plains as
they develop off of the Raton Mesa and an amorphous dryline. Given
the high based nature of the storms, and DCAPE values around 1000
J/kg, strong outflow winds around 40-50 mph will be the primary
hazard with any more organized thunderstorms. Outside of that
though, breezy conditions with scattered afternoon clouds is
expected. As for temperatures, much of the region will remain hot.
With downsloping winds and early sun, above seasonal temperatures
are anticipated for most.

Saturday - Sunday: For the weekend, more widespread active weather
is expected for south central and southeastern Colorado. The
aforementioned closed low will pass over the region through Saturday
and exit the by the end of Sunday. Other than some timing
differences, ensemble model guidance are in relatively good
agreement about this, leading to medium to high (50-70%) confidence
in this pattern evolution. As this feature passes over the area
Saturday, precipitation chances will increase area wide, especially
along the mountains where forcing will be greatest. Then Sunday as
the low treks eastward, wrap around precipitation is anticipated to
materialize, though will generally favor areas along and north of
Highway 50. With that all said, while most precipitation will remain
rain, elevations generally around and above 10,500ft will experience
snow. Along with that, severe weather may be a concern across the
eastern plains during Saturday afternoon, where the best combination
of strong shear, moisture, and instability will reside. With that
said though, confidence is low (20-30%) at this time in severe
weather development, given uncertainty in how much moisture and
instability will be present, which will highly influence the
strength of thunderstorms that do develop across the plains. As
mentioned though, this system will be exiting the area through
Sunday, and as it does so, any showers and storms that are present
are expected to lessen in coverage throughout the day, with only
isolated mountains showers persisting through the afternoon.
Otherwise during this period, breezy conditons and cloudy skies are
expected, with clouds increasing through Saturday morning and
decreasing through Sunday afternoon. Looking at temperatures, Fall
makes a return. Saturday will hover around seasonal values for late
September, while Sunday will drop to below seasonal values thanks
to a cold front passage during Saturday.

Monday - Tuesday: For the start of next week, relatively quieter
weather returns. Northwest flow will develop over south central and
southeastern Colorado behind the exiting weekend system. While
forcing will overall lessen, minor orographics, along with modest
support from a broad shortwave, will allow for isolated to widely
scattered showers to blossom along the mountains both days. Outside
of the mountains though, drier conditions are anticipated to
prevail. Beyond all that, light winds and scattered clouds are
expected for the area. As for temperatures, Fall stays in place for
a bit. Much of the region will hover around seasonal values for late
September.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 522 PM MDT Wed Sep 18 2024

VFR conditions area anticipated during the next 24 hours at all
3 taf sites, KPUB, KALS and KCOS. Winds will diurnally driven
through the period.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 3 AM to 8 AM MDT Thursday for COZ069>071.

&&

$$

SHORT TERM...GARBEROGLIO
LONG TERM...SIMCOE
AVIATION...HODANISH