Weekend storm and beyond…

It is starting to become clear that the worst severe weather potential will be south and west of KY this weekend. For Saturday, the highest risk appears to be MO, LA, MS while on Sunday the highest risk will shift to MS, AL and TN. Is anyone going chasing this weekend?

KY should still have very heavy rain from thunderstorms Saturday night as the squall line passes through the state, but the nocturnal storm passage will decrease the instability associated with the storms such that the risk of severe thunderstorms and tornadoes will be fairly low. A big story for the weekend will be the river flooding potential across areas of IL, IN and OH that received over a foot of snow from last week’s blizzard. The expected rain from this weekend’s storm along with the rapid snowmelt and the frozen ground will cause widespread flooding. Ice jams will form in areas where rivers remain iced over. Heavy snow is expected to fall on the northern fringe of this storm, with over 12″ expected across parts of IA, WI, and MI.

Looking ahead, the first part of next week will be cool and dry but another very strong cut-off low is expected to emerge from the four corners late next week. This new storm appears very similar in many ways to the Plains storms of this weekend and should produce severe weather in the southern Plains. In fact, this weekend’s low will act as the 50-50 low that will block the mid-level flow and allow the new storm to slow down and eventually occlude.

Beyond that storm, the models have a poor handle on the first week of March. The operational GFS has consistently tried to bring arctic air into the northern plains and eventually the eastern U.S., but this is not supported by the ensembles. The teleconnections offer a little support to the operational GFS, as the EPO is trending negative by 3/10 and the PNA is becoming positive. The combination of negative EPO and positive PNA would point towards a colder than average March if a blocking pattern can become sustained.

The Bottom Line:

Saturday-Sunday: Showers and thunderstorms likely Saturday night with shows likely early Sunday

Monday-Wednesday: Cool and dry (Highs upper 40s)

Thursday-Friday: Showers and thunderstorms (possible severe weather)

First week of March: Trending colder with some potential for very cold February-like blocking pattern to emerge by the middle of the month. Lots of uncertainty.

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