Nationwide
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A broad area of surface high pressure resulted in little to no precipitation throughout the contiguous U.S. from February 8 to 14. During this 7-day period, the most significant precipitation (more than 0.5 inch, liquid equivalent) was limited to the Cascades, Upper Mississippi Valley, northern New England, and the Florida Peninsula.
Following a wet December with beneficial snowfall, a persistent mid-level high-pressure area anchored near the West Coast led to drier-than-normal conditions across the western U.S. since early January. During the second week of February, above-normal temperatures prevailed throughout the West and much of the Great Plains.
The West
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An expansion of extreme (D3) drought was made to parts of south-central Montana, based on Standardized Precipitation Index (SPI) and Evaporative Demand Drought Index (EDDI) at various time scales and soil moisture indicators.
Although only light precipitation (less than 0.25-inch liquid equivalent) was observed in northeast Montana, a small area was improved from D3 to D2 due to a reassessment of indicators such as SPI values. Continued improvement of long-term SPI supported a slight reduction of D4 in northwest Montana.
Severe (D2) drought was increased slightly in coverage across southwest Utah due to low streamflows (below the 10th percentile) and 30-day SPI. 12-month Standardized Precipitation Evapotranspiration Index (SPEI) along with worsening soil moisture indicators and 28-day average streamflows supported a 1-category degradation across parts of Oregon and adjacent areas of northwest California.
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The lack of precipitation since early January resulted in 28-day average streamflows falling below the 10th percentile throughout much of western Oregon. Following the persistent dryness since early January and above-average temperatures from early to mid-February, California’s statewide snowpack decreased to 73 percent of normal on Feb 14.
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If the dry pattern persists through the remainder of February, degradations in the current drought levels may be necessary for the remainder of California.
The High Plains
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Moderate drought (D1) was degraded to severe drought (D2) across central Kansas and merged with ongoing D2 in southwest Kansas, based on 120-day SPI and soil moisture indicators. Since a 1-category degradation was made the previous week across northern Kansas and eastern Nebraska, these areas remained status quo this week given the time of year when worsening conditions are slower to be realized in terms of impacts.
Farther to the north, recent dryness with a lack of snow cover and above-average temperatures resulted in an increase of abnormal dryness (D0) and moderate drought (D1) across northern Nebraska and South Dakota. The updated depiction across the northern to central Great Plains follows closely the 30 to 90-day SPI and soil moisture indicators. Also, the SPI dating back 24 months was also weighed. Drought impacts for South Dakota include many days of high fire danger which is unusual during the winter, low stock ponds, and adverse conditions for recreational snowmobiling.
Farther to the north across northern and eastern North Dakota, SPIs at various time scales supported a 1-category improvement. Recent snowfall (6 to 12 inches) and 6-month SPIs prompted a 1-category improvement to the Denver/Boulder metro areas, while 1-category degradations were made to parts of western and southern Colorado, based on longer-term SPIs and current snowpack.
The South
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Based on 90-day SPI values and soil moisture indicators, a 1-category degradation was made to parts of Arkansas and adjacent northwest Mississippi. Impacts related to these worsening drought conditions include dry ponds and continued high fire danger.
An expansion of extreme drought (D3) was made across north-central Oklahoma, based on 90-day SPI and worsening soil moisture indicators. Persistent dryness along with periods of above-normal temperatures and enhanced winds this winter prompted an expansion of severe to extreme drought (D2 to D3 ) across the middle Rio Grande Valley. Despite a dry week, a reassessment of SPI values at various time scales and soil moisture indicators supported a 1-category improvement from moderate drought (D1) to abnormal dryness (D0) across the southern Edwards Plateau.
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According to the USDA’s National Agricultural Statistics Service, 77 percent of the topsoil moisture was rated as poor to very poor across Texas as of February 13. Nearly two-thirds of oats, winter wheat, rangeland and pastures were rated in poor to very poor condition.
Fire potential outlook
Drier than normal conditions are expected for the southern half of the West, southern and central Plains, and portions of the Southeast, with near to above normal temperatures likely as well across these areas.
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Guidance also indicates this could be a potentially busy severe weather season east of the Plains, which usually portends to periods of critical fire weather conditions on the Plains behind the severe weather.
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Above normal significant fire potential is forecast for much of the central and southern Plains through March while persisting on the High Plains and eastern slopes of the Front Range through April into May. Above normal potential is forecast in portions of south Texas and the Hill Country during February, spreading across far southwest Texas, much of New Mexico, and southern Arizona by May. The westward retreat of above-normal significant fire potential in Oklahoma, Kansas, and Texas follows the expected green-up procession. — UNL Drought Monitor and National Interagency Fire Center
