By Maggon Osmond

Why is it so HOT! El Nino or La Nina, who is to blame? Mark Eubank tells us there is a "monster high pressure" area centered around Las Vegas. This high pressure doesn't allow clouds to penetrate. The clouds are pushed around or above the high-pressure area. Thus no rain storms for Utah.

We usually blame either El Nino or La Nina for almost every extreme weather pattern; so which is it? Which is to blame for the baking weather we are receiving? The answer is La Nina. El Ninos are wetter than normal and La Ninas are usually hot and dry. La Nina summers in Utah are usually hotter than normal with an above normal number of 100-degree days. La Nina winters in Utah are usually drier than normal with lower than normal snow pack.

What is it that causes this extreme weather pattern?

The El Nino weather pattern is caused by abnormally warm water in the equatorial Pacific. It changes the wind flow and thus the storm distribution for many parts of the world.

El Nino seems to affect places like Utah in concert with what is happening in the mid-latitudes. For example, if there is an El Nino and a persistent upper-level high pressure over the Western U.S., Utah has very dry conditions. However, if there is an El Nino and a persistent upper-level low pressure, then Utah has very wet weather. So for Utah is seems that a certain type of upper-level pressure must accompany an El Nino in order to produce extreme results.

The very strong El Ninos seem to be accompanied by a western U.S. low pressure and thus bring very wet weather to the state. The two strongest El Ninos ever measured have been in 1982 and 1997. Both were very wet for Utah.

After about 12 to 18 months, the warmer water fades and colder water takes its place. The extra cold water in the Pacific leads to a weather pattern called La Nina. The La Ninas usually come very quickly after the El Nino. Several computer models indicated that La Nina could be completely in place by the end of this year.

The theory is that strong La Ninas follow strong El Ninos although that is a great simplification of what goes on. The La Nina pattern usually brings heat and drought to the mid-west part of the United States. The last strong La Nina was in 1988 when there were great crop losses and even deaths due to the heat.

In order to keep the two extreme weather patterns strait, just remember, El Ninos are wetter than normal and La Ninas are usually hot and dry.

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