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July Hottest Month on Record but is El Nino Around Corner?

10 August 2012, at 9:41am

US - The average temperature for the contiguous US during July was 77.6°F, 3.3°F above the 20th century average, marking the hottest July and the hottest month on record for the US. Drought has expanded to cover nearly 63 per cent of the lower 48 states and wildfires have consumed two million acres.

The previous warmest July for the nation was July 1936 when the average US temperature was 77.4°F. The warm July temperatures contributed to a record-warm first seven months of the year and the warmest 12-month period the nation has experienced since recordkeeping began in 1895.

Drought Hits Hard

Precipitation totals were mixed during July, with the contiguous US as a whole being drier than average. The nationally averaged precipitation total of 2.57 inches was 0.19 inch below average. Near-record dry conditions were present for the middle of the nation, with the drought footprint expanding to cover nearly 63 per cent of the Lower 48, according the US Drought Monitor.

Highgher-than-average temperatures engulfed much of the contiguous US during July, with the largest temperature departures from the 20th century average occurring across most of the Plains, the Midwest, and along the Eastern Seaboard. Virginia had its warmest July on record, with a statewide temperature 4.0°F above average. In total, 32 states had July temperatures among its ten warmest, with seven states having their second warmest July on record.

Drier-than-average conditions continued across the Central Plains and Midwest during July. Nebraska, Iowa, Illinois, and Missouri had July precipitation totals ranking among their ten driest. Maine had its fifth driest July on record.

The May-July months were the second warmest and 12th driest such three-months for the Lower 48, contributing to rapid expansion of drought. The central regions of the country were hardest hit by the drought, where ten states had three-month precipitation totals among their ten driest, including Nebraska, Kansas, and Arkansas which were record dry.

The area of the country in the worst drought categories (extreme to exceptional drought) doubled from 10 per cent last month to 22 per cent this month. The extreme dryness and excessive heat devastated crops and livestock from the Great Plains to Midwest.

Wet Conditions on West

Despite dry conditions across much of the US, California recorded its fifth wettest July on record and Nevada had its eighth wettest. Wetter-than-average conditions were also observed through the rest of the Southwest, along the western Gulf Coast, and through the Ohio Valley where West Virginia had its tenth wettest July.

According to the July 31, 2012, US Drought Monitor (USDM), 62.9 per cent of the contiguous US was experiencing moderate to exceptional drought at the end of July. This is an increase of about 6.9 per cent compared to the end of June. The maximum value of 63.9 per cent reached on July 24 is a record in the 13-year history of the USDM.

Is El Nino on the Way?

Dr Klaus Wolter from the National Oceanic and Atmospheric Administration (NOAA) believes that El Nino will soon be here.

He is analysing six weather and atmospheric pressure numbers that come from the Equatorial Waters in the Pacific Ocean. The six are the sea-level air pressure, components of the surface winds, sea surface temperatures, surface air temperatures and the cloudiness.

But prospects for precipitation are the key to crop production success in the Cornbelt in 2013, and with soil moisture rated short to very short in most of the region, precipitation will be needed.

The Climate Prediction Center indicates there are better chances for precipitation in the near future. The precipitation prediction maps are showing dryness in the Cornbelt into the early planting season, but more normal rain fall during the growing season. Winter temperature maps indicate Cornbelt temperatures above normal, which would tend to allow soil temperatures that would allow any precipitation to soak in.