7/22 Drought Monitor Update - Some Improvements In S. Plains, But California Still In Terrible Shape

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Widespread moderate to heavy showers and thunderstorms, plus unseasonably cool air, highlighted a very beneficial and welcome weather week for much of the region. Southeastward tracking thunderstorms dropped swaths of ample rain (>2 inches) on southwestern Kansas, central and southeastern Oklahoma, southwestern Arkansas, eastern Texas, and most of Louisiana. Additional heavy rains fell on southeastern Colorado, the Texas Panhandle, along the Red River Valley, and on central and southwestern Texas. 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 (multi-year) drought which has impacted hydrological interests. Taking this into consideration, 1-category improvements were made in most areas where this week’s rainfall exceeded 2 inches. A 2-category improvement (D1 to nothing) was made in extreme southeastern Texas (Jefferson County) were 8-10 inches fell. A few areas were slightly degraded as the rains missed the extreme southern Texas coast and parts of the west Texas.

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. 28-day average USGS stream flows were spotty in Texas, but most sites in Texas, Oklahoma, and Kansas were in the normal (25-75th percentile) category, including several stations in northern Texas in the above to much-above normal categories.

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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 (e.g. most of Arizona, Utah, western Colorado, southeastern California). And like the southern Plains, the balancing of short-term wetness and long-term drought tempered the potential improvements in New Mexico and southeastern Colorado. Nevertheless, where decent rains (more than an inch) fell this week and Water Year-to-date surpluses existed, a 1-category improvement was made, namely in central New Mexico (north to south) – D3 to D2, and in southeastern Colorado. D3 was slightly expanded to reflect similar conditions at various time scales in north-central New Mexico and northeastern Arizona.

In northeastern Utah, hot and dry conditions justified a general 1-category downgrade to reflect poor soil and vegetative health models. Monsoonal moisture made it north and west into the central Sierra Nevada and Lake Tahoe area, producing showers and thunderstorms that dropped 0.3-1 inches, locally to 3 inches, but these totals weren’t even close to making a dent in the long-term drought.

In California, the June 30 reservoir update (based upon 154 intrastate reservoirs) had storage at 60% of average – better than this time in 1977 where storage was at a record low of 41%. Storage totaled 17.25 million acre feet (maf), and a typical seasonal withdrawal is 8.24 maf. The last two years (2012 and 2013), withdrawal has topped 11 maf. Due to early melting of this year’s meager snowpack, withdrawal through June 30 was already at 2.1 maf (versus average withdrawal through June 30 of less than 0.6 maf).

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http://droughtmonitor.unl.edu/