Groundhog Day Superstorm??

Less than a week after a major ice storm devastated a large swath of the central United States with ice, snow and flooding rains, another even more powerful storm appears to be on the way. In fact, computer models suggest this new storm could rival some of the more famous “superstorms” of recent decades. The Groundhog Day Superstorm has the potential to produce 20+ inches of snow over the Appalachians, severe weather across the Gulf Coast, and flooding rains along the East Coast; however, the most notable impact may be the wind of 50+ mph that could batter parts of the Great Lakes region and southeast Canada. But what can Kentucky expect from this storm?

Let’s start at the outset by remembering that any storm four days out will undergo a number of subtle changes from the models and that a change in storm track of 100 miles can have HUGE repercussions as to the snow output for KY. Sunday, the day before the storm, will be beautiful across Kentucky with an offshore high providing a warm, SW flow that should lift temperatures into the 50s across south-central KY. In fact, a novice meteorologist may not even be able to identify the seeds of the impending storm. As with all “superstorms”, energy from the polar and sub-tropical jet streams must merge. On Sunday morning, the northern energy can be seen by the jet streak and vorticity over the northern Rockies while the southern energy can be seen by the jet streak over Mexico and the 1012 mb surface low over the panhandle of TX. No vorticity is seen with the southern system although the kink in the 5640 line is a giveaway. So far, there isn’t even any precipitation associated with this system.

By Sunday evening, the southern stream system has picked up some moisture from the Gulf while the northern system is producing light snows over the Rockies. Light rain showers should break out over KY Sunday night as an arctic front brings colder air into the region. By Monday morning, moderate to heavy snow should blanket much of KY. At this point, the storm, which is located along the Gulf Coast, has not yet phased. However, KY is located in the favorable left-front region of the sub-tropical jet streak which combined with the arctic boundary and influx of Gulf moisture from the storm will be enough to produce accumulating snow over KY. By late Monday, the jet streams have phased and the storm has made the northward turn, which will shut off the snow in western KY just as the storm begins to intensify. By late Tuesday, this storm will have deepend to 980 mb, which is a deepening of 28 mb in 24 hrs, which exceeds the threshold for “explosive cyclogenesis”. Some of the model runs deepen the central pressure of the storm to around 960 mb, which is equivalent to the central pressure of the March 1993 Storm of the Century (and is also equivalent to a Category 3 hurricane!!).

Most of the big weather media has jumped on this storm already. AccuWeather has a nice picture on it. The GFS ensembles also have a good consensus for both the KY snowstorm part of this system as well as the explosive cyclogenesis. The ECMWF also is on board (see hr 144).

So what does this mean for KY? The 18Z GFS snowfall map has a wide area of 6-8″ accumulations across the state although this is the highest I have seen and is likely overdone. The 12z GFS snowfall map shows 2-4″. The OZ GFS has a storm track well to the east of other models which would mean only around an inch or two of snow.

Bottom Line: There is a POTENTIAL for a significant accumulating snowfall for most of KY from Sunday night through Monday. The eastern third of the state could get buried if the storm tracks along the Appalachians, but the best that central KY can hope for is probably around 4″ or so. Regardless, it is important to keep in mind that the “historic” nature of this storm will not occur until well after the storm leaves KY.

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