934
FXUS65 KPUB 181711
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
1111 AM MDT Wed Sep 18 2024

.KEY MESSAGES...

- Dry weather next 24 hours with a Frost Advisory for the San
  Luis Valley tonight

- Warm, mainly dry and breezy conditions into the end of the
  work week with spotty critical fire weather conditions across
  the plains.

- A cooler and wetter weekend ahead, with the potential for
  strong storms across the plains Saturday and good chances
  (50-70%) of rain and mountain snow.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 406 AM MDT Wed Sep 18 2024

Dry southwest flow will remain over the region today keeping quiet
weather across the southern over the next 24 hours.  High
temperatures today will top out around to a little above climo.
Winds will be much lighter than yesterday but still breezy over the
higher elevations and far southeast plains on the east side of the
lee side low.  Overall, not much impact expected.

Efficient radiational cooling under clear dry conditions will allow
temperatures to drop to around freezing across the San Luis Valley
with probabilities of a frost looking higher. Will issue a Frost
Advisory for the San Luis Valley floor for late tonight through
early Thursday AM.  Otherwise, temperatures will be crisp and cool
with lows in the 40s to low 50s which is near climo for mid
September. -KT

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 406 AM MDT Wed Sep 18 2024

Thursday-Friday...Latest models are in good agreement on slowly
increasing southwest flow aloft across the Rockies through the end
of the work week, as a seasonably strong upper low digs across the
West Coast and into the southern Great Basin by 00Z Saturday. Warm
and dry air in place across the region through the day Thursday
leads to very spotty critical fire weather conditions across portions
the of plains, with highs expected to remain above seasonal levels
in the 80s to lower 90s across the plains, and mainly in the 60s
and 70s across the higher terrain. Seasonal overnight lows expected
into Friday morning, with some patchy frost possible across the
high mountain valleys. Increasing southwest flow induces a lee
trough across the plains on Friday, with breezy south to southwest
winds again leading to some spotty critical fire weather conditions,
especially across the I-25 Corridor. Further east, increasing low
level moisture across the plains will lead to the potential for a
few afternoon and evening showers and thunderstorms, with some
modest CAPE being progged across the far southeast plains. Friday
also looks to be the last day for above normal temperatures for a
while, with highs in the mid 80s to mid 90s expected across the
plains, and mainly in the 60s and 70s across the higher terrain.

Saturday-Sunday...While there remains differences in timing and strength
of the southern Great Basin system moving across the Rockies through
the weekend, models do agree on a much cooler and wetter weekend ahead
across south central and southeast Colorado. The latest GFS and ECMWF
operational and ensemble solutions indicate the southern Great Basin
upper low lifting out across the Four Corners region into south central
Colorado through the day Saturday, which then continues to track north
and east into northeastern Colorado Sunday morning before lifting out
into the Northern High Plains Sunday night. The Canadian suite is a tad
further south and weaker with the low opening up to a broad upper
trough moving across the region Saturday night into early Sunday morning.

With that said, all model solutions do indicate the potential for strong
to possibly severe storms across the far southeast plains Saturday, as
southerly flow along a prefrontal trough advecting low level moisture
across the plains. NBM is indicating mean CAPE across the plains of 500-
1000 j/kg, with increasing uvv and shear ahead of the system supporting
the potential for supercell development. The stronger GFS and EC closed
low solutions indicate the best chances of precipitation along and north
of the Highway 50 Corridor, with widespread precipitation developing
across south central Colorado late Saturday morning, which spreads north
and east across the eastern mtns and northern portions of the I-25 Corridor
Saturday afternoon and evening, before precipitation lifts north and east
into northeastern Colorado Saturday night and Sunday. This solution also
supports wrap around precipitation across the Pikes Peak and Palmer Dvd
region through the day Sunday. The weaker and slightly further south
Canadian solution would support the best precipitation across the
the eastern mountains and into the southern I-25 Corridor, with sfc-h7
northeast winds of 25-35kts late Saturday afternoon and night. The
latest NBM solution is closer in line with the GFS/EC solution and has
QPF of 1/2 to 1 inch north of Highway 50, with a 1/4 to 1/2 inch of
precipitation south of Highway 50. With snow levels lowering to between
10-11K ft Saturday night, there could be several inches of accumulating
snow across the higher peaks, especially across the Central mtns into the
Pikes Peak region by Sunday morning. While the amount of precipitation
across the region remains in flux and will depend on the eventual track and
strength of the passing system, temperatures will definitely cool to well
below seasonal levels through the weekend, with coolest day expected to be
Sunday, with highs in the 60s to lower 70s across the lower elevations and
mainly in the 40s and 50s across the higher terrain, save for 30s at the
peaks.

Monday-Wednesday...A generally cool and unsettled northwest flow pattern
remains in the offing for early next week. This will keep chances of
precipitation, especially over and near the higher terrain, along with
temperatures at to slightly below seasonal levels into the middle of
the work week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1111 AM MDT Wed Sep 18 2024

VFR conditions are expected at KALS, KCOS, and KPUB through 24
hours. Winds will generally be diurnally driven, though gusty south-
southwest winds between 20-25 knots are expected at all 3 TAF sites
this afternoon.

&&

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

&&

$$

SHORT TERM...KT
LONG TERM...MW
AVIATION...GARBEROGLIO