Tuesday, March 12, 2013

20 Year Anniversary of '93 Superstorm

Today and tomorrow mark the 20th anniversary of the Superstorm of '93, the biggest March snowfall in Philadelphia's history and the last time Philly picked up ten inches of snow from a single March snowfall.  The storm, a powerhouse of low pressure energy that had the equivalent strength of a borderline Category 2/Category 3 hurricane according to the Saffir-Simpson scale at its peak, developed during the 11th in Texas and in the Western Gulf of Mexico before plowing east and northeast, rapidly intensifying into the powerhouse of low pressure that brought snow to Florida and killed over 300 between the US and Cuba.

In about 24 hours, low pressure went from a reasonably strong center of low pressure in the western Gulf to a powerhouse low over Georgia that resulted in blizzard conditions near Atlanta and a foot of snow in Birmingham, Alabama.  The southern flank of the storm was memorable for its derecho that plowed through Florida and Cuba, bringing wind gusts to nearly 100 mph in Florida as it shoved through the state in a five hour timeframe.  That part of the storm wasn't the part most around here remember but most of the death and a large chunk of the property damage with the Superstorm came as a result of the severe weather associated with it.  Severe weather was also common along the Georgia, South Carolina, and North Carolina coastlines to the east of the low track.  If you have time, a lengthy post-storm assessment from the NWS includes some pictures of the damage.

North and west of the low, however, the storm's calling card was the snow.  Over a foot of snow fell in a swath from Alabama northeast through Maine, with blizzard conditions for many in between.  This is the part of the storm that most of us remember.  For Philadelphia, while snow mixed with sleet at times, it was still a rather prolific snowmaker over the span of 12-18 hours, bringing a foot of snow to the city and more to the north and west.  Over 20" was common through the Appalachians and Poconos.  Sleet and some rain cut down on those totals at the Shore and across coastal sections of New Jersey and Delaware, however, the winds were still quite prolific throughout the region and made for a miserable go of it for the entire region.

Winds gusted to 66 mph in Philadelphia, 55 mph in Atlantic City and Millville, and 54 mph in Wilmington during the storm's peak on the afternoon of the 13th, with sustained winds in Philadelphia over 50 mph around midday on the 13th the storm.  Yikes!  The aftermath of the storm was the brief but intense March cold shot -- the low temperature on March 15th was just 11 degrees, a record low for the date and the high of 30 on the 15th was also a record for a coldest high temperature for that date.

More: Superstorm 15th Year Anniversary (Phillyweather.net)