Above Normal Spring Temperatures in U.S. Continue Long-Term Upward Trend; Record Warmth in Northeast

The National Oceanic and Atmospheric Administration (NOAA)released today (8 June 2010) temperature and precipitation data for May and Spring in the U.S.  Nationwide, above-normal spring temperatures continued a long-term upward trend.  It was the warmest spring on record for eight northeastern states; and one of the top ten warmest springs for another ten states.  See the figures below.

For many states in the northeastern quadrant of the U.S., the warmth has dominated more than just this Spring.  According to NOAA:

The profound warmth in the Northeast has dominated throughout 2010 to date. Maine, New Hampshire and Vermont each had their warmest January-May on record. Massachusetts and Rhode Island had their second warmest such period. Other significantly warm states for 2010 so far were New York (3rd warmest), Connecticut and Michigan (each 4th warmest), Wisconsin (5th warmest), and New Jersey (8th warmest).

Where high temperatures have combined with low precipitation -- from Minnesota to New York and south into Maryland, drought conditions have developed.  The drought in that area is most severe in northwestern Minnesota, Northern Wisconsin and the upper peninsula of Michigan.  According to the U.S. Drought Monitor on 3 June 2010:

"Since October 1 through the end of May, Houghton, Michigan, is 11.63 inches of precipitation below normal, with only 0.74 inches in the first three months of this year.  Impacts associated with water supply and power generation are starting to become common.  Some power generators are coming close to having to shut down due to lack of flows.  Several lakes are 1 to 2 feet lower already than last year, with docks exposed to the lake bottom, with no water under them.  Since 2002, areas of Wisconsin are 30 to 35 inches below normal, which is more than a season’s worth of precipitation. "

For Alaska (which is not included in the above data) it was both warm and dry this spring, especially in May.  It was the 7th driest May on record and the 11th warmest on record.  As is the figure below illustrates, May temperatures are increasing in Alaska over the long-term as greenhouse gases accumulate in the atmosphere.

Not surprisingly, drought conditions have developed in interior Alaska -- setting the stage for an early start to the wildfire season.  See our posting, Early and Severe Wildfire Situation Develops in Alaska as Fuel Conditions Reach "Historical Maximum Levels" in Some Areas (30 May 2010).

Eagle Trail Fire, Alaska, 30 May 2010. Credit: Clinton Northway.

Here are a few other highlights from NOAA for May:

• "During May cooler-than-normal temperatures in the western U.S. were counterbalanced by warmer-than-normal temperatures in the east, creating a national temperature near the long-term average."

• "Regionally, a persistent pattern with a high-pressure ridge (associated with warmer conditions) in the east and a western trough (cooler conditions) was especially evident. The Northeast and Southeast Climate regions each had their tenth warmest May on record, while the Northwest and West had their fifth and tenth coolest May, respectively."

• "May precipitation was variable across the contiguous U.S. with the national value averaging slightly above normal. The state of Washington had its third wettest May on record and extreme precipitation events in Tennessee and Kentucky contributed to their sixth and seventh wettest such period, respectively. It was the tenth wettest May in North Dakota."

• "A storm system that stagnated over the Lower Mississippi Valley on May 1st–2nd killed 29 people and flooded thousands of homes and businesses. The storms spawned dozens of tornadoes and brought record amounts of rain to numerous locations in Mississippi, Tennessee, and Arkansas. Preliminary reports indicated that more than 200 daily, monthly, and all-time precipitation records were broken across the three states. More details can be found within NCDC's Global Hazards page."

Online Resources:

National Overview: May 2010.  From NOAA.

U.S. Drought Monitor

Northern Hemisphere Snow Cover Drops to Record Low for Month of May .  WWF Climate Change blog, 7 June 2010.