Driest Start to May in 15 Years

Driest Start to May in 15 Years
 
May 2007 has started out mild and very dry in Central Indiana. The precipitation total during the first 21 days of May 2007 at the Indianapolis International Airport has been a mere 1.07 inches. This is well below the normal value of 2.94 inches for the first 21 days of May. The average temperature for these first 21 days of May has been 65.5 degrees,  more than 4 degrees above normal.
 
So what is the reason behind this dry and mild start? The jet stream, which would typically be over the nation’s mid-section during May, has been displaced farther north. A ridge of high pressure has been present for most of the month across the Midwest, which has shifted the track of low pressure systems (and their rainfall) well north. When cold fronts have approached the area, the high pressure has held them at bay, and the sinking air associated with a high pressure system also acts to dry the air out. The end result is an extended period of sunny and dry weather.
 
This May marks the driest start to any May in the Indianapolis Area since May of 1992 when the first 21 days brought only 0.88 inches of precipitation. That month finished out with just 1.56 inches of rain, making it the 16th driest May on record.
 
The dryness is not limited to Indianapolis only. As the table below shows, May has been very dry in most of Central Indiana. Precipitation deficits so far during the month of May are between 2 and 3 inches for most sites.
 
According to the latest Indiana Weekly agricultural report, farmers in many areas are concerned about the recent lack of rain.  The next chance rain is from late Wednesday through the Memorial Day Weekend.
 
Site
May 1-21, 2007 Precipitation Total
May 1-21 Normal Precipitation Total
May 2007 Difference from Normal
Indianapolis Int’l Airport
1.07
2.94
-1.87
Lafayette
0.69
2.90
-2.21
Bloomington
1.02
3.53
-2.51
Terre Haute
0.82
3.06
-2.24
Muncie
0.70
2.77
-2.07
Shelbyville
0.55
3.07
-2.52
Indianapolis
Eagle Creek
0.77
2.94
-2.17
 
All data above is from ASOS sites. Normals refer to the period 1971-2000.
Daily CF6 Preliminary Climatological Data is available for all the sites above at:
http://www.weather.gov/climate/index.php?wfo=ind
 
Data Prepared by Logan Johnson, Climate Services Focal Point
Assistance provided by National Weather Service Indianapolis Forecast Staff
w-ind.webmaster@noaa.gov
 


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