Chris's Corner - Valentines Day Week 2022

RGEM is still a big sleet fest as well

Sorry……not sorry…….it really want to call in sick tomorrow!! I hate this scenario. Gets my blood pressure rising

On the cold side of this transition zone, moderate to heavy snow can
be expected during the late morning and afternoon. High-resolution
ensemble guidance and the National Blend of Models (NBM) show very
high (>90%) probabilities of 0.5"/hr snowfall rates Thursday
afternoon in northeast Missouri and west-central Illinois. The 12Z
HREF, being more spatially resolved horizontally and vertically, has
80% probabilities of 1"/hr snowfall rates during this time.
Conceptually, these values match well with a deeper DGZ and a band
of 850-700mb frontogenesis depicted in deterministic global and
mesoscale guidance. 6" of snow is becoming increasingly likely,
supported by high probabilities of that value from the NBM, but
localized amounts within the band exceeding 10" is certainly a
possible outcome as suggested by high-resolution guidance. One
notable area of uncertainty is the continued southerly shift of
the guidance, which would have an impact on the axis of heavier
snow. Within some high- resolution ensembles (the HREF 3.0 in
particular) a bimodal distribution of where the heaviest snow can
be seen. This forecast represents a shift to the south but this
guidance suggests that there could be room to move even further
south. The 25th/75th percentile ranges on our official forecast
also depict the uncertainty of where that axis of heaviest snow
falls.

South of the snow, rain will transition to freezing rain and sleet
during the late morning/early afternoon on Thursday. While the cold
air will move south with great pace during this time, the depth of
that cold air is quite shallow. A glaze of freezing rain is
increasingly likely, but amounts could be kept in check by the
strong winds expected tomorrow. There is some increasing concern
that measurable sleet will fall along the I-70 and I-44 corridors
during the afternoon, according to model soundings showing a
slightly deeper cold layer that would allow for sleet refreezing.
This will not only add to the increasingly-treacherous conditions
on the roadways, but also may cool the roadways more rapidly than
anticipated. Luckily, temperatures for the last few days were
well into the 60s and the roads will take a few hours at the least
to cool. However, temperatures will likely be below freezing for
several hours with precipitation falling, which will lead to ice
forming on roadways (both from falling freezing rain and freezing
of rain that has already fallen). While exactly how long this
cooldown of the roads takes is uncertain, the impacts for the
evening commute will likely be notable and travel is discouraged
at this time.

As the 850mb low shunts east of the region and the entire column
cools below freezing, a transition to snow will occur. However,
limited moisture will exist within the DGZ, leaving light snow as
the p-type where any precipitation is falling within the deformation
zone of the departing low. Temperatures will plummet into the single
digits overnight as high pressure, clear skies, and weaker winds
dominate.

Strong pressure rises behind the boundary...that's a good sign. The freeze line is roughly 75-100mi behind it.

Honestly who cares weather it’s a warning or advisory. At this point they have everything covered very well.

Glen didnt mention sleet a single time. Did mention thunder freezing rain. So, uh, there's that.

As Chris said though..heavy freezing rain just basically rolls off...and the wind will be strong also. Thunder freezing rain won't do much. Thunder sleet would be cool though.

18z euro appears a tick south

Ensembles we’re just a tick south as well

There trying to sneak that heavy snow band into the NW metro 

Verbatim... has 2" sleet 2-4" snow across the immediate metro

00 HRRR

Haha, I thought Verbatim was a model I didn’t know about.

Looks like the NAM is a skosh colder, has fr rain at 9am.

Edit..shut up 920. Lol