Does the El Nino-Southern Oscillation affect spring storms?

The El Nino-Southern Oscillation (ENSO) alters the climate all over the world. The 1997-1998 El Nino was one of the strongest on record. Consequently, 1998 is one of the warmest years on record globally. ENSO is known to impact the United States winter weather, but what does it do during the spring?

New research suggests that ENSO affects severe storms during the spring time. In general, the authors found that an ENSO warm phase (El Nino) acts to suppress the frequency of tornadoes and hail in the southern central US, while an ENSO cool phase (La Nina) increases the frequency of tornadoes and hail. 

Figure 1. El Nino influence is on the left and La Nina is on the right. Orange colors indicate less frequent, while purple colors indicate more frequent. Source: http://www.climate.gov/news-features/featured-images/el-ni%C3%B1o-and-la-ni%C3%B1a-affect-spring-tornadoes-and-hailstorms

When the sea surface temperatures over the Equatorial Pacific are above or below normal conditions, the general circulation temporarily changes. This anomaly causes the Jet Stream, over the US, to change. El Nino weakens the surface winds that cause warm, moist air to advect northwards. La Nina increases the winds. It's interesting to note that the 2010/2011 winter season was influence by a La Nina. Also, the spring 2011 severe weather seasons was one of the worst on record.

Unfortunately, the understanding of ENSO's infleunce on spring climate is less certain. Considering the severe weather season peaks in the spring for the United States, more research should be conducted to better understand ENSO's influence. 

Cheers, 

Source: http://www.climate.gov/news-features/featured-images/el-ni%C3%B1o-and-la-ni%C3%B1a-affect-spring-tornadoes-and-hailstorms

May Summary

If May gives any indication of how the summer will be, it will be a hot and dry one.

Just kidding. It does not.

So, this past May in Raleigh was a hot and dry month. The average temperature was 72.48F (3.85F above the norm), which was the 9th warmest May on record! The average maximum temperature was 83.56F (3.41F above normal) and the average minimum temperature was 61.41F (4.3F above normal).

Figure 1. The blue line is the observed daily max temps and the orange is the "normal" daily max temps

Figure 2. The blue line is the observed daily min temps and the orange is the "normal" daily min temps

Although is was a warm May, Raleigh only reached the 90F temp twice. Raleigh reached the upper 80s quite frequently, which caused the abnormal heat. 

As for the precipitation, Raleigh only received 3.04" of rain. Luckily, Tropical Storms Ana brought us precipitation. However, that's not the case for western N.C. Just one county to our west (and most of NC for that matter) is under a slight drought. Click this link for more information. 

Figure 3. The yellow color indicates areas of abnormally dry conditions. 

Like I stated in the previous post, El Nino is expected to play a role in our climate this year, so it will be interesting to see how it unfolds. 

Cheers,