Central Indiana May 2010 Climate Summary

Central Indiana
May 2010 Climate Summary
24th Warmest on record at Indianapolis
52nd Wettest on record at Indianapolis
It was a warm start to the month as high temperatures were in the 70s to lower 80s through the first week. The passage of a strong cold front on the 7th however ushered in a much drier and cooler airmass from the northwest, with highs from the 8th through the 10th falling back mainly into the 50s. The coldest nights of the month also took place during this three day stretch, as clear skies and light winds associated with the high pressure produced an ideal setup for temperatures to fall into the lower and middle 30s. 
Temperatures briefly returned into the 70s and 80s through the 14th, before a sluggish upper level low arrived on the 15th and took the next five days to move out of the Ohio Valley. The upper level system brought an abundance of clouds and periods of light rain showers, which held daytime temperatures down in the upper 50s and lower 60s.
The arrival of a broad upper level high pressure ridge on the 22nd signaled a pattern change for central Indiana, as southerly winds brought warm humid air into the region for the rest of the month. High temperatures remained above 80 degrees from the 23rd through the end of the month, with several locations reaching 90 degrees for the first time in 2010. Lows also were warm through this period, generally remaining above 60 degrees.
May 2010 Avg Temp
May 2010 Difference from normal
Lowest Temperature
89 on 26, 27 and 30
37 on 9
91 on 30
34 on 9
91 on 30
33 on 10
Terre Haute
89 on 24
36 on 9
89 on 23 and 27
35 on 9
91 on 27
35 on 10
Indy – Eagle Crk.
89 on 26 and 30
38 on 10
At Indianapolis, there were 9 days with below normal average temperatures, 22 days with above normal average temperatures.
                                              May 2010 was the 24th warmest in the Indianapolis area since 1871.
Monthly rainfall during May in central and southern Indiana varied from 4 inches to over 9 inches.   The wettest areas received nearly 200% of the normal rainfall for May, while the driest around 75%. 
The rainfall pattern of May was more typical of April. At Indianapolis, measureable rain fell on 19 days during the month.   May began on the wet side with 1 to 5 inches of rain falling south of Interstate 70 in the first two days. The heaviest rain during this period fell along and south of the Ohio River. 
A prolonged wet pattern began on the 10 and continued through the 21st.   Much of central and southern Indiana received 2 to 5 inches of rain during this time. The airport recorded rainfall on 12 consecutive days…the second longest of record.
A convective weather pattern dominated the last part of May. Rainfall was more widespread and varied greatly within short distances. Localized heavy rains of 1 to more than 2 inches would occur in a 1 to 3 hour period. Rainfall during the last 8 days of May varied from a few hundredths of an inch to more than 3 inches.
The highest flood levels in two months occurred along the Wabash River following localized heavy rains in eastern Illinois and western Indiana on the 21st.    Warmer weather and widespread rainfall after the 21st allowed flooding to end by Memorial Day. 
Wet weather during May limited agricultural field activities. The May 23 Indiana Crop Bulletin reported planting of soybeans had fallen behind the 5-year average pace… limited amount of corn and soybean acreage damaged by standing water or flood waters and some very weedy fields.
May 2010 Precipitation
May 2010 Difference from Normal
Wettest Day
Longest Dry Stretch
0.71” on 2
4 days 22-25
1.00” on 11
9 days 22-30
1.04” on 12
5 days 22-26
Terre Haute
1.30” on 21
4 days 22-25
1.04” on 1
4 days 22-25
0.97” on 17
5 days 22-26
Indy – Eagle Crk.
0.54” on 20
4 days 22-25
                                                               May 2010 was the 52nd wettest in the Indianapolis area since 1871.
Severe Weather

A series of fronts impacted the region during the first week of the month, producing scattered strong thunderstorms. Scattered thunderstorms produced isolated wind damage across southwest and south central Indiana on the 12th. The most significant severe weather event of the month occurred on the afternoon of the 21st as a frontal boundary crossed the region. A supercell moving across Knox and Martin counties produced up to 2.5 inch hail in diameter. Scattered wind damage also occurred across southwest and west central Indiana. Isolated wind damage, hail and localized flooding occurred on the 27th and 31st as thunderstorms developed along weak frontal boundaries. 
For information on severe weather in other areas during April, visit the Storm Prediction Center “Severe Weather Event Summaries” website at http://www.spc.noaa.gov/climo/online/
At the Indianapolis International Airport, the peak wind gust this month was 47 mph from the west on May 8. Fog or haze was observed on 17 days, with dense fog occurring only on the 13th. Thunderstorms were observed on 11 days during the month.
June 2010 Outlook
The official outlook for June 2010 from the Climate Prediction Center indicates an equal chance of above, near, or below normal temperatures across central Indiana. At Indianapolis, the average temperature for the month is 71.7 degrees. The outlook also calls for a greater chance of above normal precipitation. The average precipitation for June at Indianapolis is 4.13”.
Data prepared by the Indianapolis Forecast Office.

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