â??There is always a St. Pattyâ??s Day storm.â?? This matter- of-fact statement will often be heard when the subject of U.P. weather comes up; it is one of our more enduring weather myths. Evidence shows this supposed phenomenon is just that; a myth. In over 50 years, starting from 1949, there has been only one St. Patrickâ??s Day with a bona fide snowstorm; that was in 1965 (Images 1 & 2 above). If you adopt the liberal view that a St. Pattyâ??s day storm can be either early or late, and include the entire month of March, the statistics are still much less than impressive.
First, we must define the term â??snowstorm.â?? For our purposes, it will be characterized as a heavy fall of snow over a relatively short period of time, i.e. a 24 hour period. All data comes from National Weather Service (NWS) records in the Marquette area beginning in 1949. A â??heavy fall of snowâ?? will be delineated in this way: nine inches or more in a 24-hour period in the city of Marquette at lake level, and 12 inches or more at the Negaunee Township site in the higher elevation west of town where snowfalls are usually heavier (The NWS moved their offices and hence, their observation point, from the city â??up the hillâ?? to Negaunee Township in 1979.).
For the entire month of March, only 11 heavy snowstorms occurred in the 30 years from 1949 to 1978; a paltry figure of 37%. From 1979 on, the percentage rose to just over 50, higher, but still hardly worthy of the description â??always.â??
A Post-St. Pattyâ??s Day storm is looming. Low pressure will develop over the central Plains tonight and drift eastward to near Kansas City. It will then hook to the northeast probably staying just south of Upper Michigan Tuesday night into Wednesday. Right now, it appears that the western third of Upper Michigan has the best chance of receiving heavy snow accumulations so the NWS has issued a Winter Storm Watch for Tuesday night into Wednesday there. Farther east, some heavy snow is possible, especially over central sections Tuesday night into Wednesday. The eastern and far southern U.P. may get enough warm air aloft to lead to a mixture of snow, sleet, freezing rain and rain.