June 2011: another month of exceptional extremes for the U.S.

June 2011 was another month of remarkable extremes over the U.S. Overall, it was the 26th warmest and 19th driest June for the lower 48 states, according to the National Climatic Data Center. Extreme heat gripped much of the South, with Texas experiencing its hottest June on record, and 13 other states recording top-ten hottest Junes. Accompanying the heat was intense drought--New Mexico had its driest June on record, and four other states had top-ten driest Junes. While the southern Plains' 1950s drought of record is unsurpassed in terms of duration, the current drought in parts of Texas is more intense than the 1950s drought when measured by the Palmer Hydrological Drought Index. The heat and drought contributed to the worst fire year in U.S. history, with 4.8 million acres burned by the end of the month, more than double the average from the previous ten years.

While the South baked and burned, California experienced its wettest June on record, and heavier than normal precipitation and prolonged snowmelt during the spring caused June flooding in Idaho, Montana, North Dakota, Utah, and Washington. For the 3-month period April-May-June, the NOAA Climate Extremes Index indicated that it was the most extreme such period on record in the U.S. for precipitation, as measured by the percent area of the U.S. experiencing top 10% wettest or driest conditions. Heavy 1-day precipitation events were also at an all-time high during April-May-June 2011. Data for the Climate Extremes Index goes back to 1910.


Figure 1. Exceptional heat gripped most of the South during June 2011, with Texas experiencing its hottest June in 117 years of record keeping, and 13 other states recording a top-ten hottest June. Image credit: NOAA/NCDC.


Figure 2. Exceptionally dry conditions accompanied the intense heat in the South during June 2011, with New Mexico experiencing its driest June in 117 years of record keeping, and four other states recording a top-ten driest June. Image credit: NOAA/NCDC.

Tornado activity died down in June
According to data from the Storm Prediction Center, there were 177 preliminary tornado reports during June, which is below the national average for the month. On June 1st, a strong tornado tracked 39 miles across Massachusetts, marking the second longest tornado track on record for the state.

The Atlantic is quiet
A tropical wave near 10°N, 55°W, about 500 miles east of the southern Lesser Antilles Islands, is moving west at 15 - 20 mph, and will bring heavy rain to the southern Lesser Antilles and the northeast coast of South America on Tuesday and Wednesday. Wind shear over the wave is low, 5 - 10 knots, but the wave is too close to the Equator to leverage Earth's spin in time for development. NHC is giving the wave a 10% chance of developing into a tropical depression by Wednesday.

The NOGAPS models is predicting that a strong tropical disturbance could develop in the Gulf of Mexico's Bay of Campeche by Sunday, similar to how Tropical Storm Arlene developed at the end of June. The latest runs of the other reliable models do not predict any tropical cyclone development of note over the next seven days, though the GFS model was showing development of a system off the coast of Africa this week, in its run from Sunday night.

Jeff Masters