690
FXUS65 KPUB 220608
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
1208 AM MDT Sun Sep 22 2024

.KEY MESSAGES...

- Widespread showers/scattered thunderstorms across most of
  southern Colorado this evening and overnight, then
  precipitation intensity/coverage begin to fade early Sunday
  morning.

- Snow levels drop down to around 9000 feet early Sunday
  morning, though most accumulating snow (5-10 inches) will stay
  across the higher peaks at/above 10kft.

- Below average temperatures throughout the majority of the
  week, returning to normal by the end of the week.

- Dry conditions are expected throughout the week.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 352 PM MDT Sat Sep 21 2024

Currently, upper low over nern AZ at mid-afternoon, with expanding
area of showers and thunderstorms over much of the region as upward
vertical motion increases across srn CO. Strongest storms so far
today have been over the San Luis Valley, where weak instability
(CAPE around 500 J/KG) and strong wind shear/upward motion were
generating some fast moving convection. Hail threat with these
storms will be limited by weak instability, but will need to watch
for at least a low end severe wind threat across the Valley through
00z given storm motions of 50-60 mph.

For the remainder of the afternoon into the evening, shower and
thunderstorm coverage will expand across the area as low approaches,
with HRRR suggesting a rather robust band of thunderstorms crossing
the mountains 23z-03z, then impacting the I-25 corridor and eastern
plains 02z-07z. Will continue with high pops and a mention of
thunderstorms all areas, as strong forcing will overcome weak
instability and keep tsra chance going until at least midnight. Snow
levels hangs out between 9-10k feet through the evening, though
wouldn`t be surprised to see stronger convection drive it lower
toward 8k feet at least briefly, though accums should remain mainly
over the peaks. After midnight, low passes overhead with vertical
motion gradually diminishing from sw to ne as main deformation zone
shifts into nrn CO. Overnight QPF, starting at 00z, will range from
a half inch to slightly over an inch over much of the higher
terrain, while valleys and I-25 corridor see numbers around a half
inch. Plains should see a quarter to half inch overnight, perhaps a
little heavier far southeast corner if stronger convection over ern
NM/wrn TX can hold together as it comes north this evening. Overall,
made only a few minor changes to ongoing forecast, as previous set of
grids appear to have a good handle on things.

Sunday, upper low gradually shifts out of Colorado into nwrn KS by
late afternoon, though moisture and instability will linger across
the area. Still a good deal of showers early in the morning over the
eastern mountains and plains, with most activity then weakening/
ending by noon. A few showers/weak storms could re-fire over mainly
the mountains in the afternoon as mid-level lapse rates remain
rather steep, though not expecting anything particularly strong or
widespread. It will definitely feel like fall across all the
area temperature-wise, with max temps only in the 50s/60s at
lower elevations, 40s/50s mountains.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 352 PM MDT Sat Sep 21 2024

The closed low that has been impacting the short term forecast
continues its journey towards the northeast, but a lingering trough
will still be overhead at the beginning of the long term forecast
period, which will bring some light rain below 12kft and light snow
above 12kft over the eastern San Juan Mountains. The strong low
pressure system brought cold air over the region, and that will
continue during the overnight where low temperatures will be in the
30s and 40s over the mountain valleys and the plains. Currently it
doesn`t seem that any frost products will be needed, but it is
close, so we`ll need to keep monitoring.

Below average temperatures are expected throughout the majority of
the week over the plains and mountain valleys. On Monday, the high
temperatures will be in the upper 60s to low 70s over the plains and
mountain valleys. A weak shortwave will begin to pass over Colorado,
once again bringing light snow over 12kft and rain below 12kft over
the eastern San Juan Mountains. Otherwise dry conditions and light
winds everywhere else.

Tuesday through Saturday:

The rest of the period will have some influence from a tropical
system that will be impacting the southern U.S. Therefore, there is
some uncertainty, depending on the tropical system`s path. Overall,
the flow over Colorado is expected to be fairly weak with ridging
aloft developing over the western half of Colorado with northerly
winds over the eastern half. There isn`t precipitation being
resolved for the rest of the forecast period, just dry conditions
with temperatures reaching closer to seasonal by the end of the week.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1158 PM MDT Sat Sep 21 2024

Upper low across south central Colorado will pivot north and
east into northeastern Colorado through the late morning, with
mid level easterly flow slowly becoming more northerly late
the morning and into the afternoon. This will keep showers
ongoing along with MVFR and IFR cigs in place at COS, PUB and
ALS through the late morning. Cigs gradually improve into the
afternoon with COS likely the last to improve to VFR conditions
after 18Z, with developing low level east to southeast upslope
winds.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon MDT Sunday for COZ058-060-
082.

&&

$$

SHORT TERM...PETERSEN
LONG TERM...SKELLY
AVIATION...MW