Source: droughtmonitor.unl.edu
Map released Aug. 27, 2020 | Data valid Aug. 25, 2020
This week’s drought summary: This U.S. Drought Monitor week saw continued intensification of drought across parts of the western U.S. including Northern California, the Great Basin, Southwest, and parts of the Intermountain West where hot and dry conditions continued and large wildfires burned in California and Colorado. In Northern California, the National Interagency Coordinator Center is reporting 34 uncontained large fires with approximately 1,276,751 cumulative acres burned (all active fires) and more than 11,000 personnel deployed to the region.
Further east, drought-related conditions continued to deteriorate in areas of West Texas where significant rainfall deficits (four to eight inches) have been mounting during the past 90 days as well as extreme heat and drying winds that have stressed crops and degraded rangeland conditions. In the Trans Pecos region of West Texas, the August 2019 to July 2020 period was the warmest on record—according to the National Oceanographic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI).
Along the Gulf Coast of Louisiana, Tropical Storm Marco made landfall this week, but fortunately weakened before making landfall causing no significant damage. A much more powerful storm, Hurricane Laura (Category 4), is expected, however, to make a Gulf Coast landfall along the border of Louisiana and Texas on Thursday (Aug. 27)—where a life-threatening storm surge, hurricane-force winds, and widespread flash flooding are expected.
In the Midwest, above-normal temperatures and dryness in Iowa during the past 90-day period (three to seven inch rainfall deficits) led to expansion of areas of drought statewide. In the Northeast, areas of drought intensified in portions of the region including New Hampshire where streamflow levels were well-below-normal level (<10th percentile) and reports of some agricultural impacts emerged.
South: On Monday, Tropical Storm Marco made landfall near the mouth of the Mississippi River after weakening significantly thus sparing the residents of the Gulf Coast of Louisiana any significant impacts while a strengthening Hurricane Laura is expected to make landfall as a dangerous hurricane early Thursday morning.
On this week’s map, drought intensified (due to continued hot temperatures and mounting precipitation deficits) across Texas with western Texas as a focal point of deterioration. According to NOAA NCEI, the Trans Pecos Climate Division (Texas, Division 5) observed its warmest July on record as well as its warmest August-July period on record.
Elsewhere in the region, drought intensified on the map in southwestern Oklahoma where 4-to-6 inch rainfall deficits, since June 1, exist and rangelands reportedly are in poor condition. For the week, average temperatures continued to be above normal (2 to 8 degrees) across Far West Texas while areas to the east were below normal (2 to 8 degrees).
In terms of precipitation, moderate accumulations (2 to 5 inches) were observed in portions of eastern Louisiana and southern Mississippi while some light precipitation (generally <1 inch) was observed along the Texas Gulf Coast and central Texas.
Looking ahead: The NWS WPC 7-Day Quantitative Precipitation Forecast (QPF) calls for very heavy rainfall accumulations in association with Hurricane Laura making landfall along the Gulf coast of Louisiana and Texas. Along the coast, rainfall accumulations are expected to range from three to 15 inches while areas inland in the Lower Mississippi River Basin are expected to see moderate-to-heavy accumulations (two to ten inches).
In the Midwest, moderate rainfall accumulations (two to five inches) are expected across parts of the region including Missouri, Iowa, Minnesota, Wisconsin, and Michigan as well as in parts of the Northeast.
Out West, generally dry conditions are forecasted with the exception of some light precipitation (generally less than one inch accumulations) in isolated areas of Arizona, New Mexico, and Colorado.
Further northward, isolated mountain showers and thunderstorms are expected in the Northern Rockies of Wyoming and Montana with light accumulations (generally less than one inch).
The CPC 6 to 10-day Outlook calls for a moderate-to-high probability of above-normal temperatures in the Far West, Southwest, South, Southeast, and Mid-Atlantic states, while a high probability of below-normal temperatures are expected across the remainder of the West, Plains states, and the Midwest. In terms of precipitation, there is a moderate-to-high probability of above-normal precipitation across most of the eastern half of the U.S., Northern Rockies, and Alaska. Drier-than-normal conditions are forecast for the Pacific Northwest, Four Corners states, and the Gulf Coast region of Texas and Mississippi.