Figure 1. Maximum and minimum temperatures and precipitation at Columbus, IN
Winter is coming to a close in about a month, and the coldest of the days should be behind us at this point. Here in Indiana, El Nino usually points to a warmer, drier kind of winter. With the past El Nino being considered one of the strongest on record, how much did the warm Pacific Ocean affect Indiana?
The temperature and precipitation graphs around the state look somewhat similar to Figures 1 (Columbus) and Figure 2 (Lowell).
High temperatures generally trended unseasonably warm right around the winter holiday, December 23 or 27, and around February 2. During both periods, record warm temperatures were set depending on location within the state. The southwestern portion of the state had a four day record shattering streak of warm temperatures, while the more impressive warmth was experienced in February at some more northern locations (Figure 2).
Figure 2. Maximum and minimum temperatures and precipitation at Lowell, IN
Going around the state, high temperatures this winter varied from 70 degrees Fahrenheit in Evansville to 64 degrees in Fort Wayne, with Lowell and Columbus falling in line at 66 and 68 degrees, respectively. Low temperatures over the winter so far have varied from 8°F in Evansville to -3°F in Lowell, generally on either side of the precipitation event on January 16. None of the low temperatures this year have been very close to record-setting. For December and January, average temperatures around the state varied from 5.4 to 6.5°F above 30 year normals, with the state average running just under 6 degrees above normal. For an El Nino year, this kind of warmth falls in line well with our expectations.
While we would expect drier than usual conditions during an El Nino year, this expectation has not been the reality. The multiple one inch or greater precipitation days have skewed our average to wetter than average across the state. Far southeastern Indiana comes in the driest, at 96% of normal precipitation for December and January and a total value of 6.46 inches. Meanwhile, West Central Indiana received 145% of normal precipitation with 7.89 inches across the two months. For the vast majority of precipitation events, location in the state was not consequential for the occurrence of precipitation but amount was highly variable by location. For instance, the rain or snowfall around the December 28 timeframe was fairly consistent in occurrence from Figure 1 to Figure 2, but the amount of total precipitation varied significantly across sites.
Heading into the growing season, our past winter has likely not affected pest or weed pressures significantly differently than in previous years. Chilling hour accrual was much less than normal in December but colder temperatures in January have helped considerably. El Nino weakening is expected, with transition back to ENSO-neutral conditions in late Spring or early Summer. Until that time, under El Nino conditions, we expect near normal temperature patterns with normal to slightly drier conditions, particularly for Southern Indiana in March and Central Indiana in May. To analyze this data for yourself, head out to agclimate4u.org and check out the Climate Patterns Viewer Decision Support Tool on their web site.