313
FXUS65 KPUB 151746
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
1146 AM MDT Sun Sep 15 2024

.KEY MESSAGES...

- Scattered thunderstorms over the region today with an
  isolated strong thunderstorm over the far eastern plains
  during the late afternoon.

- Near critical fire weather conditions across the region today,
  but no fire weather products will be issued due to not meeting
  thresholds for a Red Flag Warning.

- Pattern becomes more active with the potential for some
  strong thunderstorms for Monday and Tuesday, mostly for gusty
  winds.

- Dry and windy for Wed and Thu with the potential for critical
  fire weather conditions across portions of the SE plains.

&&

.UPDATE...
Issued at 1013 AM MDT Sun Sep 15 2024

A quick update was issued this morning to increase chances for
thunderstorms in the SE Plains slightly and increase cloud
coverage across the area today. A few radar returns are
developing on radar, however, given the drier lower levels,
this is likely all virga. Otherwise, the going forecast
highlighted in the Short Term forecast below remains in place
with no changes. /04-Woodrum/

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 342 AM MDT Sun Sep 15 2024

The flow regime aloft will be from the southwest throughout the day
today with an embedded shortwave propagating over southern Colorado
during the afternoon and evening. The shortwave will spark mountain
showers and thunderstorms and will then spark showers and
thunderstorms over the plains, specifically over La Junta and east,
during the mid-to-late afternoon. Perhaps a few gusty winds and some
light to moderate rainfall is expected over the mountains, but the
instability over the plains will be ranging from 600 to 1000 J/kg,
meaning a stronger storms possible between the hours of 2PM and 8PM.
Main impacts will be mainly nickel sized hail and 40-50 MPH wind
gusts, however under the strongest storms quarter sized hail and 60
MPH wind gusts will be possible. Weak high based thunderstorms are
expected over the rest of the region, but models sounding illustrate
a very convincing dry layer above the surface that most, if not all,
of the rain that falls out of the elevated convection will dry and
just be virga. That being said, strong wind gusts of around 30
to 40 MPH will be possible underneath these storms.

Near critical fire weather conditions are expected today across the
lower elevations. The mountain valleys are expected to have too high
of RH, but the winds will be very close to Red Flag Warning (RFW)
threshold, the I-25 corridor will have low enough RH values but the
wind speeds will not meet RFW thresholds, and the far eastern plains
will have too high of RH values but will have strong enough winds -
so overall the atmospheric variable for critical fire weather
conditions are not lining up - and even if they do line up, the time
threshold of 3 hours are not expected to be met. Therefore, no fire
weather products will be issued.

Another warm day is expected today with high temperature values in
the upper 80s to low 90s over the plains, which is around 5F higher
than normal for this time of year, and the the mid to upper 70s for
the mountain valleys which is right around normal for this time of
year. Low temperatures tonight will be in the 50s to low 60s over
the plains and the 40s over the mountain valleys.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 342 AM MDT Sun Sep 15 2024

A rather active weather pattern is shaping up as a closed low
takes shape across NV on Monday which lifts out to the north of
the area on Tuesday, only to be replaced by another western
U.S. upper low as the pattern reloads through late week. The
second system carries the potential for a more southern storm
track.

Mon and Tue...An uptick in thunderstorms can be expected as moisture
return in southerly flow advects back into the mountains with the
subtropical moisture tap.  With increasing flow aloft, wind shear
will increase to around 40-50 kts in the afternoons and low level
moisture return could yield sufficient CAPE (up to 1000 J/kg in the
moister models) for a few strong to severe thunderstorms if
sufficient instability can be realized. This looks most likely
Mon across the southwest and central mountains, but with a
couple rounds of forcing and waves of showers and thunderstorms
earlier in the day, there is some question on the amount of
instability that will be present in the afternoon. As storms
move out onto the plains, soundings exhibit more inverted V
structures with gusty outflow winds up to 60 mph possible. It
will be an earlier show with the onset of thunderstorms on
Tuesday as forcing from the upper wave maximizes earlier in the
day. There is a little better cooling aloft and hence more CAPE,
though soundings are still rather dry in the low levels. We are
outlooked for a marginal severe risk for Tuesday across most of
the plains, mainly for wind given the potential for gusty
outflows and momentum transport from strong winds aloft. It will
be getting windy through this period as well, which raises fire
weather concerns some, however it appears low level moisture
will increase sufficiently to keep relative humidities above
critical thresholds both days. Temperatures will remain above
normal across the plains with only spotty light rainfall
expected. The mountains and valleys should fair better with near
to slightly below normal temperatures and better chances for
wetting rains, especially across the eastern San Juans. In fact
NBM probabilities of over 1/2 inch of liquid over the 48 hr
period range from 40-60%...and 20-40% for amounts greater than
an inch. All other areas show significantly less precipitation
across the area.

The next upper low reloads across the western U.S. for Wednesday and
Thursday and carries the potential to have a more southern storm
track as it moves across the U.S. Rockies late week.  Wednesday and
Thursday look dry and windy and carry the potential for critical
fire weather conditions across the southeast plains though details
this far out could still change.  Current NBM suggests probabilities
of 50% or greater for critical fire weather conditions along the I-
25 corridor and adjacent plains which maximize on Thursday.
Thunderstorms return to the forecast late week into next weekend
as the system crosses the U.S. Rockies with fairly good
consensus that it will move across CO. We may be dealing with
dry line thunderstorms at some point across the far eastern
plains if the storm track holds true.

Long range models portray the potential for a stronger cold front to
penetrate CO sometime late weekend into early next week which could
bring us a taste of fall.  Confidence on the details is low at this
point, but it is September. -KT

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1139 AM MDT Sun Sep 15 2024

VFR conditions will mostly prevail across the terminals
throughout the TAF period as the lower levels remain dry. Some
high-based showers and thunderstorms will develop this
afternoon nearby the terminals, however confidence is not high
enough in coverage/restrictions to mention as a TEMPO group.
Thus, prevailing VCSH is mentioned starting at 19Z at Alamosa
and at 21Z at Pueblo and Colorado Springs. Showers and storms
will diminish by around 02Z as VFR conditions continue overnight
into early on Monday. Winds will mostly be southerly through the
period at 10-15 kts with gusts to 20-25 kts through 01Z and
then decreasing to less than 10 kts overnight.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...WOODRUM
SHORT TERM...SKELLY
LONG TERM...KT
AVIATION...WOODRUM