FOUS11 KWBC 072022
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
322 PM EST Thu Nov 7 2024

Valid 00Z Fri Nov 08 2024 - 00Z Mon Nov 11 2024


...Central/Southern Rockies and Adjacent High Plains...=20
Days 1-2...

...Heavy snow and major impacts continue for the Southern=20
Rockies and Interstate 25 corridor through Friday...

Deep low pressure drifting south over eastern AZ this afternoon
will pivot east over southern NM tonight before swinging northeast
up the eastern NM/TX Panhandle border Friday then shifts up the
central Great Plains Friday night/Saturday. Pacific and Gulf of
Mexico sourced moisture will continue to wrap in ahead of this low
center and a developing surface trough extending from the southern
Plains into central CO. Jet dynamics above frontogenesis along with
topographical lift will allow renewed heavy precip over the Sangre
de Cristos and adjacent High Plains by early Friday.=20
This lift is through the DGZ which should allow large dendrites and
rapid accumulation. Indeed the 12Z HREF mean 1-hr snowfall product
features 1-2"/hr snow rates centered on the Raton Mesa 12Z to 22Z=20
Friday. Day 1 PWPF for additional >12" is around 90% along the=20
Raton Mesa to near the western OK Panhandle border. Please see
updated Key Messages linked below.

Snow shifts north over the eastern slopes and High Plains of CO on
Friday, while a pivoting dry slow shuts off precipitation over NM.
The strengthening theta-e advection will result in an impressive=20
mid-level TROWAL pivoting NW into CO, which along with elevated
instability, especially on the periphery of the dry slot, and=20
upslope flow will driving heavy snow rates over central/eastern=20
CO, especially where the DGZ deepens. The setup also supports a=20
pivoting band of heavy snow around and perhaps north of the Palmer
Divide south of Denver Friday evening. Day 1.5 PWPF for >8"
are 50-80% over the Palmer Divide, but caution is advised with the
decrease in values in the valley between the Palmer Divide and
Raton Mesa where banding could easily overcome marginal thermal
conditions and produce heavy snow in areas of central/eastern CO=20
regardless of elevation.=20

As the low occludes and shifts over Neb Friday night/Saturday, the
moisture moisture fetch is shunted east and thermals farther east
do not support snow, so the heavy snow threat generally ends in CO.=20


The probability of significant ice across the CONUS is less than=20
10 percent.


Jackson



...Winter Storm Key Messages are in effect...

Southern Rockies and adjacent High Plains:
https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late=
stKeyMessage_1.png__;!!DZ3fjg!7XDq_NvZyxvJRdYbO0XSOEUih6c7hySGUslchv-cGXbAD=
G_ZrGNdmS98kIQX-6hBPZI9vAXf7tXDPjpWb9xPzhhbIzc$=20


$$

=3D =3D =3D
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