Cold fronts moved across the eastern two-thirds of the U.S., bringing cool air and showers and thunderstorms, holding off drought degradation across the middle Plains and triggering improvements in Texas and Oklahoma, the U.S. Drought Monitor said Thursday.
Lows dropped into the forties as far south as Kansas, and 7-day temperatures averaged more than 12 degrees F below normal in Oklahoma and Arkansas, reports this week's drought map author, David Miskus of the National Oceanic and Atmospheric Administration.
In contrast, to the cold fronts, a ridge of high pressure over the West kept the weather hot and mostly dry. Weekly temperatures averaged 4 to 8 degrees F above normal in the Northwest and Great Basin, with highs reaching triple-digits in many locations.
Crops and pastures in nearly all Midwestern and northern Plain states were in good condition as of July 20, according to NASS/USDA. One small exception was found in southern South Dakota where the rains have missed in both the short and medium-term, Miskus reports.
In the Southern and Central Plains, widespread moderate to heavy showers and thunderstorms, plus unseasonably cool air, highlighted a very beneficial and welcome weather week for much of the region.
Even after a dry 7-day period in much of Texas last week, 60-day precipitation is generally at or above normal in most of the state, along with Oklahoma, Kansas, New Mexico, and eastern Colorado.
The issue, however, is to balance the short-term wetness with the long-term drought which has impacted hydrological interests, says Miskus. Taking this into consideration, he said, one category improvements were made in most areas where this week's rainfall exceeded 2 inches.
The July 20 NASS/USDA state summaries mentioned that pastures were greening up across much of Texas and Oklahoma with the recent rains and lower temperatures, and most crops benefited from the moisture and lack of excessive heat.
Somewhat similar to the southern Plains, abundant moisture triggered scattered moderate to heavy showers and thunderstorms in parts of New Mexico and southeastern Colorado, but totals quickly dropped to zero in western sections.
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Also like the southern Plains, the balancing of short-term wetness and long-term drought tempered the potential improvements in New Mexico and southeastern Colorado, but some areas saw a one-category improvement.
A second consecutive week of hot and mostly dry weather greatly increased moisture demand across the Pacific Northwest, triggering several pockets of degradation, especially in northern Idaho.
In California, the June 30 reservoir update had storage at 60% of average – better than this time in 1977 where storage was at a record low of 41%. No drought changes were noted in California as more than 80% the state remains in extreme or exceptional drought.
On the other side of the country, moderate rain was enough to make a one-category improvement in southeastern Kentucky, while 2-3 inches across south-central and eastern Tennessee removed 60- and most 90-day deficits there.
Little or no rain, however, fell on northern and western sections of Kentucky and Tennessee, maintaining abnormal dryness and slightly expanding D0 into western and northern Kentucky.
With this short-term dryness, USDA/NASS reported that 48% of the state's topsoil moisture was very short to short. Fortunately, subnormal weekly temperatures tempered the effects of the dry weather, with most crops and pastures in fair to good condition.
In the Southeast, moderate to heavy showers and thunderstorms and cool air reduced many D0 areas. The exceptions to this included small D0 expansion in central Alabama and southern Georgia.
Source: U.S. Drought Monitor