Weather Differences Nov/Dec 2011

Wind - Days with Gusts >=10mph Year Oct Nov Dec Jan Feb Mar

Surface Temp – Temp at 500 ft AGL (20 mb Above Surface ~ 154 m)

Surface Temp minus 20 mb above surface Temp

What do these graphs show us? Dec 2007 and Dec 2011 had few very strong inversions Dec 2009, Dec 2010, and Jan 2010, Jan 2011 had much higher numbers of strong and very strong inversions and few no inversion days.

Oct 2011 Distinguished by lack of any cold weather.

Nov 2011 Windy and above normal Temp first half. Extremely cold with light wind second half. Average T -8.2F, (10.8F below normal) 6 th coldest Nov (109 years of record), coldest since 2006 Nov 2011 inversion strength not remarkable

Dec 2011 First 3 weeks warmest on record (tied with 1986 with T ave 13.1F first 22 days). Gusty winds most of first 3 weeks. 26 days with snow >= Trace (indicates cloud cover which causes weaker inversion) Mean T925mb-Tsfc = 4.5 C >> mean of 7.8 for all 60 Decembers on record.

Ave Dec Lapse Rate Sfc-100m AGL

Ave T 925mb – T sfc for Dec

Nov-Dec 2011 Different! Nov 2011 inversion strength not remarkable but windy first half, and very cold second half. Dec nd weakest inversion on record for Dec and much windier!