Buckle up buttercup…
Models have again trended upward in QPF with this system and
accordingly snowfall amounts have nudged up another tick. Thermal
profiles support snow ratios generally in the 12-13:1 range
through the overnight hours with this system, with decreasing
snowflake quality expected in the afternoon as temperatures warm
and ascent through the colder reaches of the thermal profile
diminishes. The going forecast snowfall totals has 2-3" generally
west of I-55 and the Chicago metro with 1-2" expected north of a
Paxton to Valparaiso line, and up to an inch for areas south.
There continues to be a "streaky" fgen signal in the guidance
coincident with modest EPV reductions indicative of at least some
potential for slantwise parcel accelerations. Taken together, this
suggests brief periods of higher snowfall rates (0.5" per hour)
are possible but will be rather ephemeral for any one location.
Thus suspect there could be narrow ribbons of locally higher
amounts than advertised depending on where these set up.
Given model trends, wouldn`t be surprised if another uptick in
snowfall amounts becomes warranted, but confidence wasn`t high
enough to do so with this update. Additionally, if a more robust
fgen band is able to set up, there could be a localized minimum in
amounts on the northern edge. Nevertheless, be prepared for
slippery travel conditions overnight tonight through Saturday
morning.
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