Winter predicted as mild, dry

Iowa's upcoming winter should be milder than normal, according to the annual forecast by the National Oceanic and Atmospheric Administration.

A moderate El Nino, the periodic warming of central and eastern Pacific tropical waters, will shift the jet stream to the south, according to Mike Halpert, deputy director of the NOAA's Climate Prediction Center, which released its annual December-through-February outlook on Thursday.

Some precipitation that normally falls on the Upper Midwest will shift to the south, and there will be fewer outbreaks of arctic air in Iowa and other Midwest states, Halpert said.

In terms of precipitation, however, the NOAA model shows no tendency for Iowa to receive either more or less than normal.

Halpert said the NOAA's winter predictions, begun in the mid 1990s, have established an accuracy record of about 50 percent, with better results in El Nino years.

Iowa State Climatologist Harry Hillaker said the first two weeks of October have been cooler and wetter than normal - a pattern that is consistent with past El Nino influences.

The average statewide temperature for the first 14 days of this month has been 44.9 degrees, 11 degrees below normal and well below the previous record of 48.3 degrees for the same period in 1917, Hillaker said.

Given the El Nino influence, however, Hillaker noted that the cold October is “probably not” a portent of a colder-than-normal winter.

“El Nino typically brings us unusually cold weather in October and November followed by temperatures above normal from December through march,” he said.

The statewide average rainfall for the first two weeks of October, he said, has been 2.3 inches - nearly as much as the 2.52 inches the state normally receives for the entire month of October.