Wow! Grand Rapids in taking this seriously...
-- Increased chances for impactful mid-week winter storm --
Confidence is growing that there will be a winter storm either
directly impacting or in the vicinity of Lower Michigan. In fact,
ensemble guidance has begun to converge on a solution that, should
it occur, would be reminiscent of our recent December 22, 2022
blizzard. This would mean widespread snow accumulations well over 6
inches, followed by lake effect snow along with very strong
northwest winds that could produce blizzard-like conditions
Wednesday morning. However, precipitation type is far from certain;
a significant rain component remains possible and this could
significantly curtail snow accumulations.
While what`s described above is far from certain at this point, I
still feel it is worth mentioning now as a possibility for the
following reasons:
1) It is not too early to be thinking about contingency plans for
possible travel and power disruptions next week.
2) There has been a signal for a major pattern shift starting nearly
a week ago. This has consistently featured a deep, strongly phased
western U.S. trough resulting in surface cyclogenesis in the lee of
southern Rockies. These have a strong climatological propensity to
track northeast towards the Ohio Valley, often while deepening.
3) Past storms in recent memory exhibiting this pattern showed
remarkable predictability and consistency in model guidance leading
right up to the event. This presumably has much to do with inherent
predictability associated with deep longwave troughs such as the one
we`re dealing with now.
4) Ensemble solutions, particularly the ECWMF Ensemble (ECE),
indicate potential for explosive cyclogenesis as the surface low
tracks toward the Ohio Valley. The ECE mean MSLP has dropped to 980
mb, which would imply that several ensemble member solutions feature
minimum pressures significantly less than that. Not surprisingly, we
are now seeing Shift of Tails (SoT) values in the ECE approaching 2
or greater over parts of Lower Michigan. This means that there are
several ensemble member solutions behaving as extreme outliers
relative to ECE model climatology. This also emphasizes strong
positional sensitivity to the forecast when dealing with what could
be a very deep surface low setting up somewhere.
While it`s easy to focus on what snow occurs (which undoubtedly
could be especially jarring given the winter that we`ve had so far),
we are just as concerned about the wind threat that may manifest on
the back side of the exiting, deepening low. The official forecast
will continue to smear wind speeds downward due to averaging of
model solutions, but it should be noted that we could in fact
experience very significant northwest winds and gusts that may
impact much of Lower Michigan sometime in the middle of the coming
week.