Reviewing May 2011

Thanks to a very warm finish, May 2011 goes down as the 6th warmest May since 1872 as monthly temperatures averaged out to 67.4 degrees, 3.9 degrees above average.   Believe it or not, May 2011 was warmer than May 2010 (67.3 degrees).     Spring 2011 also ended up as the 6th warmest -- 56.1 degrees for the average temperature between March and May, which was not as warm as last Spring (warmest since 1872 at 58 degrees).    May 2011 was buoyed by a very warm finish -- the average temperature the last eight days of May was 11.3 degrees above where we should be.

May 31st's high of 94 degrees equaled the hottest May high temperature in fifteen years -- the last time the city reached 94 in the month of May was May 20th, 1996.   The last time May had a higher high temperature than 94 was in 1991 (97).

Rainfall as we get into summer can be very localized -- and some spots can be rewarded with too much rain while others get much less.  This May showed that to be the case -- Philadelphia's monthly total of 1.91" was half of what constitutes average rainfall for the month locally.   Allentown picked up 4.37" of rain for the month, just 0.10" below average while Reading picked up 5.36" and was nearly an inch of rain above where they should be.   Philly ended up in a bit of a rainfall donut hole compared to most everyone else in the past month.

Reviewing First Half of May 2011

Through Monday, May 2011 has been a seasonable month overall.   Temperatures have averaged 1.4 degrees above normal, much of that brought to us by a warm spike on May 3rd when temperatures reached 83 degrees in our warmest reading this month so far.   Temperatures outside of May 3rd have generally been within a couple of degrees of average from day to day, thanks largely to a blocking pattern that has kept us in a state of constancy for days on end (last week and so far this).   In fact, outside of five days this month (including today) high temperatures have been in the 70's each day (12 of 17, pretty decent consistency).

Rainfall through yesterday had only totaled 0.86" in Philadelphia, a little more than an inch below average.  With our current pattern in place, we should be able to get out of the rainfall hole rather quickly over the coming days.