We are almost at the halfway point of the year, midway between last New Year’s Day and next New Year’s Eve. That makes it the ideal time for a snapshot of how this year’s basic climate numbers — temperature and precipitation — stack up against the long-term averages. If you look city by city, there’s a lot of variation but overall for the region we do have some comparisons. Thanks to the cold weather in late winter/early spring, temperatures for the year are still running a good bit below average. And while the snow was around a fair amount, the year started off drier than average. Recent rains though have put us a little above average through the first half of the year.
As for the rest of the nation, there’s a stark east-west divide in temperatures. Many cities out West had higher than normal temperatures, and some — Las Vegas, Phoenix, Sacramento, San Francisco and Tucson — had the warmest such period on record. While San Juan, PR, also set a record high for this stretch, most cities in the eastern part of the nation (north of Florida) were relatively cool. Baltimore; Fayetteville, Ark.; Memphis; Minneapolis; Mobile, Ala.; Rockford, Ill. and State College, Pa. all experienced among of the coolest first six months on record.
New research has shown that unusual waviness in the jet stream appears to be largely responsible for this hot/cold divide. Some scientists go further, arguing that the waviness is a consequence of climate change, although the question is far from settled.
There was also a notable difference in precipitation, largely between east and west as well. Only Minneapolis set an all-time precipitation record, but Albany, Ga.; Mobile, Ala.; Great Falls, Mont.; Duluth, Minn.; Baltimore; and Philadelphia had much more rain and snow than normal. However, the drought that has persisted particularly in California and generally in the West shows up starkly in the numbers out of Los Angeles, Sacramento and San Francisco. Precipitation in those cities has consistently been far below average. And it’s been even lower in Albuquerque, Dallas-Fort Worth; Phoenix; Tucson and El Paso, as well as southern Florida (Ft. Myers, for example, has seen near-record-low precipitation).