Nationwide
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This U.S. Drought Monitor week saw some modest improvements in drought conditions across portions of the Southwest, southern Great Plains, South, lower Midwest, and parts of the Northeast.
Drought-related conditions deteriorated in southern California, the southern Great Basin, Texas, Minnesota, and parts of New England. In California, storm activity during the weekend delivered beneficial rain and snow to central and northern California; however, the southern part of the state remained dry. Since January 1, areas of California—including portions of the eastern Sierra and Sacramento Valley—have received less than 25 percent of average precipitation. The impact of both short- and long-term dryness in parts of California has been affecting the cattle ranching industry with numerous drought impact reports describing severe effects on pasture and rangeland conditions as well as reports of ranchers having to sell livestock. Fortunately, another round of storms is expected to impact Northern California this week, bringing valley rains and mountain snows to the region.
In the southern Great Basin, record dryness during the past 6-month period led to an expansion of areas of Exceptional Drought (D4) in the eastern Sierra Nevada and southern Nevada. In the Southwest, both Arizona and New Mexico received light rains across parts of the lower deserts as well as some mountain snowfall in northern Arizona and northern New Mexico, providing a much-needed boost to soil moisture levels.
Elsewhere, above-normal precipitation during the past 30-to-60-day period and snowfall this week in northern portions of the Texas Panhandle and Oklahoma Panhandle led to the removal of areas of drought. Further to the south in the Hill Country and South Texas Plains, drought intensified in response to persistent warm and dry conditions and mounting precipitation deficits ranging from 2-to-8+ inches during the past 90-day period. Conversely, areas along the coastal plains of northeastern Texas received 1-to-2+ inch accumulations during the past week leading to widespread improvements on the map.
In the Midwest, wetter-than-normal conditions during the past 30-to-60-day period led to minor improvements on the map in central Illinois and northern Indiana. Likewise, portions of western New York saw improvement on the map in response to recent storm activity.
The West
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During the past week, areas of the West received much-needed rain and snow over the weekend, with mountain snow observed in the Cascades, Sierra Nevada, ranges of central/eastern Nevada, the Uinta Mountains, and across areas of the Rockies from Montana to New Mexico.
Snowfall accumulations ranged from 6-to-24+ inches in the higher elevations. In the California mountains, the current statewide soil water equivalent (SWE) for the date (Dec. 14) is 47 percent of normal—up 11 percent since last week. The current regional breakdown is as follows: Northern Sierra/Trinity–46 percent, Central Sierra–53 percent, and Southern Sierra–29 percent.
On the map, Severe Drought (D2) areas and Extreme Drought (D3) expanded in southern California, where precipitation during the past 90-day period has generally been less than 25% of normal. These areas largely have missed recent storm events that have impacted central and northern portions of the state. In southern Nevada, areas of Exceptional Drought (D4) expanded in Clark County where McCarran International Airport (through Dec. 1) logged its driest 6-month period (June 1 to November 30) on record with only a trace of precipitation observed for the period.
In Arizona, Extreme Drought (D3) areas expanded in southwestern Arizona where Parker, Arizona, along the lower Colorado River, has observed no precipitation since June 1—making it the driest 6-month (June 1 to November 30) on record. Elsewhere in the state, some minor improvements were made in central Arizona and northeastern Arizona on the Navajo Nation. During the past week, precipitation brought some minor improvements in soil moisture.
In northern New Mexico, some minor improvements were made on the Sangre de Cristo Range map near Taos, where soil moisture levels improved and snowfall during the past week bumped a few snow telemetry (SNOTEL) stations (Gallegos Peak, Tolby) above normal levels for the date. In southeastern Idaho, areas of Moderate Drought (D1) were reduced in response to several SNOTEL sites (Prairie, Camas Creek Divide) reporting above-normal SWE.
The High Plains
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On this week’s map, areas of the region—including southwestern Kansas and northeastern Wyoming—saw modest improvements, including a reduction in areas of Severe Drought (D2) in Wyoming and areas of Moderate Drought (D1) in southwestern Kansas where recent snowfalls have helped to improve local conditions.
The week’s average temperatures were near to slightly above normal across most of the region with eastern portions of the region observing the most significant positive temperature anomalies ranging from 3-to-12 deg F above normal. According to the NOAA National Operational Hydrologic Remote Sensing Center, the Upper Midwest Region was only 16.4 percent covered in snow (a reduction from 30.3 percent last month) with an average depth of 0.2 inches and a maximum depth of 30.5 inches.
The South
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On this week’s map, drought areas intensified and expanded in the Hill Country and South Texas Plains, where warm and dry conditions continued this week. In these areas, 90-day precipitation deficits ranged from 2-to-8 inches, and current soil moisture levels were below average according to the NASA Short-term Prediction Research and Transition Center (SPoRT) soil moisture monitoring products.
According to Water Data for Texas (Dec. 16), monitored water supply reservoirs are currently 79.9 percent full—with reservoirs in the eastern half of the state ~80–90 percent full while reservoirs in the western half of the state were generally less than 40 percent full. In the far northern portions of the Texas Panhandle and Oklahoma Panhandle, conditions improved on the map in response to short-term precipitation, including snowfall observed during the past week with accumulations ranging from 1-to-8+, according to NOAA NOHRSC.
In eastern portions of Texas, northwestern Louisiana, and southeastern Oklahoma, precipitation during the past week (1-to-3 inches) led to improvements in areas of Moderate Drought (D1). Average temperatures for the week were below normal (1-to-4 F) in the northern Texas Panhandle, Oklahoma Panhandle, and central Oklahoma. At the same time, other areas in the region were 2-to-10+ F above normal.
White Christmas
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According to John Baranick, meteorologist of DTN, a storm is expected to cross the middle of the country next week, just before Christmas. However, the arctic vortex’s absence has resulted in an active southern jet stream resulting in Pacific air masses moving from the Pacific Northwest to the Southern Plains and through the Mid-Atlantic over the last few weeks. Baranick notes the models do not indicate any “significant intrusions” of any arctic air through the end of the year despite lower than average temperatures this past week.
Some areas will likely get some snow, but the exact location is hard to pinpoint with the seven-day time frame. With the lack of a polar vortex, above-normal temperatures usually precede and follow systems moving into the country. Usually, the northern half of the country by the Canadian border sees a white Christmas, but the grass is still green or uncovered in some spots. —UNL Drought Monitor
