Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
405 PM EST Sat Feb 08 2020

Valid 00Z Sun Feb 09 2020 - 00Z Wed Feb 12 2020


Days 1-3...

...Northern Plains to the Northeast...
A dynamic, fast-moving shortwave is expected to eject east from
the northwestern U.S. into the northern Great Plains Saturday
night, and from the northern Plains into the Upper Great Lakes on
Sunday.  WPC PWPF continues to reflect a strong signal for
moderate to heavy snows, developing from eastern South Dakota to
southern Wisconsin Saturday night and Sunday.  Low-to-mid level
frontogenesis along with favorable upper jet forcing, are expected
to help support moderate to heavy snowfall bands developing north
of the associated low track.  The 12Z HREF shows this potential -
with several members indicating hourly precipitation rates of
0.10-inch or more developing over eastern South Dakota, moving
east across southern Wisconsin near the Iowa border overnight,
before shifting into Wisconsin during the day on Sunday.  The WPC
PWPF reflects a small northerly shift and an overall trend shown
toward heavier amounts that was shown by many of the daytime model
runs.  For the 24-hr period ending 00Z Monday, the latest WPC PWPF
indicates that amounts of 6-inches or more are likely for portions
of eastern South Dakota, southern Minnesota, far northern Iowa and
much of central and southern Wisconsin.

Models show a less dynamic system moving east of the Great Lakes
Sunday night, with generally light amounts spreading east in the
warm air advection pattern preceding the low.  WPC PWPF indicates
little potential for widespread heavy amounts across the Northeast
on Day 2 (ending 00 Tuesday).  Highest probabilities for amounts
of 6-inches or more center across the Tug Hill Region and western
foothills of the Adirondacks, where easterly flow behind the
departing system may support lake-enhanced snow showers --
bolstering snowfall totals.

...Southwest/Central and Southern Rockies...
Potential for heavy snow is expected to increase from the central
into the southern Rockies and across portions of the Southwest as
an upper low closes off over Southern California Sunday night
before moving east across the Southwest Monday and Tuesday as it
interacts with a northern stream trough digging through the Great
Basin into the Southwest.  Significant snows are possible along
the Mogollon Rim into the White Mountains of eastern Arizona and
along the central to southern Colorado and northern New Mexico
ranges.

For Days 1-3, the probability of significant icing (0.25-inch or
greater) is less than 10 percent.

Pereira