Saturday, January 21, 2012

Weather History: Last Subzero Low In Philadelphia


Thursday marked the 18th anniversary of Philadelphia's last subzero low temperature and what was the coldest day in Philadelphia in 60 years.  January, 19th, 1994 featured a morning low in Philadelphia of -5 degrees, which was not only a record for the date but also one of the coldest lows the city has had in January, bested only by -7 on two occasions in the early 1980's during some notorious arctic cold snaps that gripped the Eastern US.   The 1994 arctic outbreak isn't remembered as much around these parts compared to "Cold Sunday" in the early 80's or some of the late 70's arctic shots.  January 1994 is remembered locally for its ice storms but this arctic cold shot carried a lot of pop as a myriad of winter storms in early January laid the groundwork and snow cover over the Midwest for a massive ooze of arctic chill that lead to a parade of record lows being broken across the eastern half of the country.

Lows on January 19th in the Delaware Valley included -8 in Trenton, -13 in Reading, -11 in Allentown, and -5 in Wilmington.  "Highs" for the day generally only inched above zero in a number of spots...reaching just 3 in Trenton, 6 in Philadelphia, and 1 (yeah, that's it) in Allentown and Reading.   Wind chills stayed below zero throughout the day with breezes that were in the ten mile per hour range in the afternoon adding just enough bit to make it feel several degrees colder.

When you blend together the low and high for an average temperature, the "average" of 0.5 degrees for January 19th, 1994 in Philadelphia is the fourth lowest daily temperature average on record...in other words, it was the fourth coldest day since 1874.  Only December 30th, 1880 (high of 5, low of -5), February 10th, 1899 (high of 5, low of -6), and February 11th, 1934 (high of 10, low of -11) were able to out-cold January 19th, 1994.   To put the shot of cold in perspective, since the 1994 cold outbreak there have been only three days in Philadelphia where the average temperature (high and low) was at ten or below for the day, none since January 2004.  That current streak is not the longest...it had been nine years between such days prior to the January 1994 cold wave, with the last uber cold day in January 1985 forcing President Reagan's second inaugural ceremony indoors in Washington.

The 1994 wave was one of the rare cold outbreaks in the country's history that even forced schools to shut down in Minnesota by order of the state's governor...temperatures in Minneapolis reached -26 with wind chills below -45 on January 18th...and "highs" in Minneapolis on the 18th only reached -17.