Severe to extreme drought
expanded across much of the West and into the northern High Plains
during July (U.S. Drought Monitor for July 3 vs.
July
31). Scattered showers
and thunderstorms brought limited short-term relief to some
parts of the drought-ravaged Southeast, while dry conditions
expanded moderate to severe drought into parts of the Great Lakes
and mid-Atlantic regions. By the end of the month, moderate to
severe drought generally stretched in an inverted "U"
shape from the Southeast through the northern Plains to the
Southwest.
In the southeastern anchor of the inverted "U", extreme to
exceptional drought was concentrated across much of Alabama,
Georgia, and Tennessee. The dryness has been especially acute for
the
last six to eight months. Statewide, Tennessee had the driest
January-July in the 113-year record, with Alabama second driest and
Georgia fourth driest. Most of the Southeast states ranked in the
top ten driest for year-to-date
precipitation.
Excessive heat and drought, combined with low humidities and steady
winds, resulted in widespread wildfires this month across
much of the West, especially the
northern Rockies. The largest wildfire in state history flared
up in Utah. Idaho had the second driest March-July and
January-July, while Montana ranked ninth driest for June-July. It
was the hottest
July on record for Idaho, Montana, and Wyoming, and second
hottest for Nevada. About two-thirds of the western U.S.
(Rockies westward) fell in the
moderate to extreme drought category, and about half fell in
the
severe to extreme category (as defined by the
Palmer Drought Index) by the end of this month.
For July, four states ranked in the top ten
driest category, with the most severe dry anomalies
concentrated in the northern Plains. South Dakota had the fourth
driest July and Minnesota the seventh driest July on record. The
remnants of Hurricane
Cosme brought heavy
rain to eastern parts of the Big Island, but Hawaii had
below-normal rainfall across most of the islands this month,
continuing a dry trend which has been going on for the
last 12 months or longer. The rainfall pattern over Alaska
and Puerto
Rico was mixed during July. |
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The prolonged drought
prompted several states to take remedial action. In early July,
Gov. Bredesen requested a federal designation of natural disaster
for agriculture for all 95 counties in Tennessee to help farmers
who have suffered crop and livestock losses as a result of extreme
drought conditions. All 67 counties in Alabama were designated by
the USDA in July as natural disaster areas due to drought. Near the
end of the month, Gov. O'Malley asked the USDA for a Secretarial
Disaster Designation for those Maryland counties impacted by dry
weather and excessive heat in June and July.
Hundreds of daily
maximum temperature records fell across the West during the
month. The record and near-record heat in the northern Rockies and
northern High Plains magnified evaporation, which exacerbated the
drought conditions. Pocatello, Idaho reported the warmest July on
record, as did Missoula, Kalispell, and Butte in Montana. Other
temperature records: Missoula recorded a new all-time record high
of 107 °F and had 11 days with highs of 100 °F or greater
during July, shattering its 1936 annual record of 6 days. Bozeman,
Montana set a new all-time record high temperature several times
during July, exceeding the 1941-2006 record of 103 °F six
times. Miles City, in eastern Montana, reported 110 °F on July
23, which tied its second-hottest day on record behind 113 °F
on July 18, 2003.
The drought and heat wave
ravaged pastures and rangeland from the Southeast to the Great
Lakes, and across much of the West.
Two-thirds or more of the pasture and rangeland was rated poor
or very poor in Maryland, Michigan, Minnesota, Nevada, and
Virginia, with up to 97 percent in California. Soils (both
observed and modeled)
dried out, rivers and streams (both observed
and modeled)
shrank, and vegetation
was stressed. |