Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 03/12/21

Area Forecast Discussion

National Weather Service Pueblo CO

 600 PM MST Thu Mar 11 2021

.UPDATE...
Issued at 553 PM MST Thu Mar 11 2021

Updated to cancel the Red Flag Warning for Las Animas County.

&&

.SHORT TERM...(This evening through Friday)
Issued at 359 PM MST Thu Mar 11 2021

...Potential for some patchy Freezing Drizzle tonight El Paso county
but expecting warm ground to minimize impacts...

Upper low across southern CA will slowly migrate southeastward into
western AZ/southern CA during the afternoon.  This puts the forecast
area under strong southwest flow aloft.  Cold front across the
plains has held in with temperatures only warming into the 50s.
Southerly winds off the Raton Ridge have dried surface dew points to
near critical thresholds around KTAD, but so far have stayed just
shy. Latest runs of the HRRR have backed off on northern extent of
the drying moving off the Raton Ridge but being within 3% of
critical humidity thresholds at KTAD...will hang on to the Red Flag
Warning along the Raton Ridge through the early evening as there is
still time for sufficient drying to take place. Areal extent may be
more limited to southern portions of Las Animas County.

Overnight...cooler air makes a push back westward with another round
of stratus developing across the southeast plains.  Some
WAA/overrunning will produce some rain showers across the eastern
plains towards morning while shallow upslope/saturation across El
Paso county could produce some areas of freezing drizzle or flurries
towards morning.  Depth of moisture in model soundings suggests ice
processes won`t be present with super cooled liquid the primary
result in and near the Palmer Divide. Fortunately with residual heat
in the ground think this will mitigate impacts quite a bit with
mainly light patchy icing on cold surface the main risk. Therefore
no highlights expected. Scattered showers will be possible along the
Continental Divide as well, but any precipitation will be light at
this point given main forcing is still well off to the west.

Friday will be a transition day across southern Colorado. Models
have delayed the onset of precipitation some but with overrunning
overtop the cold front Friday expect showers to break out across
portions of the plains during the afternoon with emphasis across the
Pikes Peak region given good south southeasterly fetch and
orographic component.  Will also see snow showers expand across the
mountains along the Continental Divide as forcing approaches from
the southwest and area comes under better upper level difluence in
the afternoon.  It will be windy once more across the mountains and
San Luis Valley.  Southeast plains will see increasing easterly flow
as it feels the affects of the approaching low to the west but gusts
will be around 20 kts in the afternoon as compared to 30 to 40 kts
out west.  Clouds will likely hang in and increase into the
afternoon across the southeast mountains as upslope flow
strengthens. -KT

.LONG TERM...(Friday night through Thursday)
Issued at 359 PM MST Thu Mar 11 2021

1) A High Impact Winter Storm starting Friday night and continuing
through the Weekend, with heavy snow, strong winds and potential
blizzard conditions across portions of south central and southeast
Colorado.

2) Uncertainty continues on exact timing and track of the system
leading to uncertainty on snow amounts.

3) Potential for a few strong thunderstorms across the southeast
plains.

A Pacific storm system spinning off the California Coast continues
to be forecast to slowly move north and east across across the
Desert Southwest through the day on Friday. While models continue to
differ on timing and track with this cut off system, the initially
slightly slower and further south solution of EC/EPS and Canadian
models, where the cut off low is moving into the Four Corners region
Saturday morning continues to the preferred solution at this time.
With this preferred solution in mind, we have expanded winter storm
watches across the rest of the higher terrain and upgraded the
winter storm watches for Pikes Peak and Teller County, as well as
northern El Paso County, to a winter storm warning at this time.

Friday night-Saturday...This initial track across the Colorado/New
Mexico border through the day Saturday would bring a round of
moderate to heavy precipitation across south central and southeast
Colorado, favoring the areas over and near the higher terrain with
increasing and deep (Sfc-H7) east to southeast flow. Snow levels
look to remain relatively high (5500-6500) with mixed precipitation
across the I-25 corridor and rain across the far southeast plains.
Increasing southerly flow and waa aloft ahead of this system will
also lead to increasing instability across the eastern Plains which
would support the potential for thunderstorms late Friday night and
early Saturday morning, along with the potential for strong to
marginally severe storms across the far southeast Plains later
Saturday, as a developing surface low lifts out across the plains.
Snowfall amounts through the period look to range from 4 to 8 inches
across the higher terrain areas, with 1 to 4 inches possible across
the valley locales and lower elevations, though relatively warm
southerly flow aloft and daytime temperatures may limit
accumulations across the lower elevations.

Saturday night-Monday...Deformation band precipitation spreads east
Saturday night, with the vertically stacked system across the
southeast plains Sunday morning, before slowly lifting north and
east into west central Kansas Sunday night. Moderate to heavy snow
is expected to develop over and near the higher terrain Saturday
night, with strong northerly winds expected to develop on the back
of system, which will keep heavy snow and blowing in place across
the Pikes Peak region through the day Sunday before slowly
diminishing Sunday night into early Monday morning, as the system
continues to move east. There is likely going to be precipitation
wrapping around the backside of the low extending into across the
southeast Plains, though with the uncertainty of the track of the
system, there remains uncertainty on how much, what form and how far
south this precipitation will extend. Again, with a relatively warm
system and temperatures expected to be in the 40s to around 50
across the far southeast plains, most of this precipitation would be
in form of rain at this time. Snow totals through this timeframe
look to range for 6 to 12 inches across the higher terrain, greatest
across the Pikes Peak and Palmer Dvd region, where expected
conditions may warrant the upgrade of the the current winter storm
warning to a blizzard warning, as travel may become difficult to
impossible.

Although current watches and warnings are in place across south
central and southeast Colorado, there still remains uncertainty of
the track of this cutoff low pressure system which could increase or
decrease snow totals and impacts across all of south central and
southeast Colorado. Please stay tuned to the latest forecasts and
updates to this significant winter storm system.

Monday night-Thursday...Another storm system looks to move across
the region in the late Monday night through Wednesday timeframe,
however latest models indicate significant differences on its
strength and location as it moves across the Rockies. For now, NBM
keeps slight and chance pops across the area through this period,
with the best pops over and near the higher terrain.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 359 PM MST Thu Mar 11 2021

VFR conditions currently dominate all TAF sites. There is going to
be an increasing cloud deck later on this evening due to some low
level moisture advecting in for KCOS and KPUB as the winds become
more easterly. LIFR conditions will more that likely be the case for
KCOS after around 08Z due to low CIGs near the surface and low VIS
in FZFG, and there is the potential for this cloud deck to become
thick enough to cause some -FZDZ as well. KPUB will also see low
CIGs but should remain at around 010 AGL. There is also a slight
chance for -FZDZ at KPUB as well although the vertical depth of the
low level moisture does not appear to be as significant as further
to the north. The low clouds will begin break by around 15Z for KCOS
and 17Z for KPUB, respectively, although some MVFR conditions could
still be possible for a few hours after. Some -SHSN are possible
over the San Juan and Sawatch Mountains, so be advised of reduce VIS
if flying at lower levels in the vicinity of these areas.

Winds will also continue to be a little strong and gusty at KALS out
of the southwest and for KCOS and KPUB out of the south-southeast,
until later this evening, therefore some light to moderate CAT could
be possible at lower levels. winds will diminish throughout the
night and then increase again by tomorrow morning but should not be
as strong as they were today. Still there could be some light CAT
for larger aircraft and moderate CAT for smaller aircraft after
around 17Z for KALS, and 19Z for KCOS.


&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from late Friday night through late Sunday
night for COZ059-062-072>080-083-085.

Winter Storm Watch from Friday afternoon through late Sunday
night for COZ058-060-061-063-066-068.

Winter Storm Warning from 11 PM MST Friday to 6 AM MDT Monday
for COZ081-082.

Winter Storm Warning from 5 AM MST Saturday to 6 AM MDT Monday
for COZ084.

&&

$$

UPDATE...28
SHORT TERM...KT
LONG TERM...MW
AVIATION...STEWARD