New computer models and satellite data were recently used to examine climate changes over the United States during the past century. The study was performed by NASA scientists at the Goddard Space Flight Center.
The study indicated that major climate changes at least partially resulted from cooler than normal sea-surface temperatures in the Pacific Ocean regions combined with warmer than usual sea-surface readings in the tropical Atlantic and Caribbean waters.
According to NASA, this sea-surface temperature “diversity” helped create drought and extreme heat conditions across areas east of the Rockies to the Atlantic coastline, especially over the nation’s midsection. The upper-level jet stream patterns across North America would often change. Strong high pressure locked over the nation’s midsection for many months would keep out the normal moisture flow from the Gulf of Mexico.
This drought and heat pattern in the eastern two-thirds of the U.S. occurred about every 75 years. In addition to 2012, midwestern droughts occurred previously in the 1780s, the late 1850s and early 1860s and the early to mid-1930s – the Dust Bowl days. During those years, many cities ran out of potable water supplies and crops died in the parched fields.
During each of these major droughts, the Pacific Northwest, western Canada and Alaska tended to be in a cycle that was wetter, cooler and often snowier than normal. This has once again been true: Alaska had its snowiest winter overall in at least 200 years in 2011-’12.
Much of Asia and central and southern Europe also saw an unusually snowy and cold this past winter. The canals froze in parts of Venice, Italy. Schools in Rome were closed for the first time due to heavy snowfalls. Earlier this month, Secretary of State Hillary Clinton saw rare snows in South Africa, the first measurable snowfall in Cape Town since at least 1968.
We’re finally seeing a break from the heat and dryness. On Tuesday morning, thunderstorms were rumbling across our region, with moisture reported in Eastern Washington and North Idaho. Before Tuesday, the last time measurable rain fell at the airport was on July 20.
Despite the recent weather change, it still looks like warmer and drier than normal weather well into October.
There may be brief showers or a thunderstorm, but mostly fair skies should be the rule for at least the next 60 days. There should be a few more 90-degree-plus afternoons between now and the middle of September.