Map released June 11, 2020 | Data valid June 9, 2020
This week’s drought summary: A strong upper-level ridge developed over the Southwest at the beginning of June, and expanded east to the Southern Great Plains. Seven-day temperatures (June 2 to 8) averaged more than 10 degrees above normal across much of the southern to Central Great Plains until a strong cold front arrived on June 9.
From June 6 to 8, a vigorous upper-level trough progressed east and resulted in varying amounts of rainfall and much cooler temperatures from the Pacific Northwest to the Northern Rockies and Northern Great Plains. Around the periphery of the upper-level ridge, mesoscale convective systems with severe thunderstorms and locally heavy rain (more than two inches) occurred from the Upper and Middle Mississippi Valley southeast to the mid-Atlantic. After spending multiple days stationary over southern Mexico, Tropical Storm Cristobal tracked north across the Gulf of Mexico and made landfall in southeast Louisiana on June 7. The heaviest rainfall occurred to the east of its landfall. Seven-day precipitation amounts (ending 12Z June 9) exceeded five inches, with locally higher amounts, from the Mississippi Gulf Coast east to the Florida Panhandle. A weak surface low remained located across the Gulf of Alaska at the beginning of June. The most widespread rainfall (more than one inch) occurred across southeast coastal Alaska, while scattered convection raised wildfire concerns over the interior of Alaska. Rainfall was suppressed across Hawaii this past week, while heavy rainfall occurred well west of Puerto Rico during the first week of June.
South: Drought continues to rapidly develop and intensify across the Southern Great Plains. During a relatively wet time of year, precipitation has averaged less than 50% across much of western Oklahoma and the Texas Panhandle. This lack of rainfall coupled with periods of much above normal temperatures and strong winds have dried out topsoils quickly. According to the USDA’s National Agricultural Statistics Service, topsoil moisture being rated as short or very short across Oklahoma increased from 23 to 53% during the past week. Conversely, 1 to 2-category improvements were made along the Gulf Coast. Total rainfall amounts, associated with Tropical Storm Cristobal, included eight inches at Pascagoula, Mississippi. Moderate long-term drought remains designated for the Mississippi Gulf Coast due to precipitation deficits dating back to 90 and 180 days.
Looking Ahead: On June 11, a cold front is forecast to cross the eastern U.S. Surface high pressure, behind this front, is likely to result in mostly dry weather from the Appalachians west to the Rockies. Along with the dry weather, a return of above normal temperatures is likely across the central and southern Great Plains. From June 11-15, the heaviest precipitation (locally more than one inch) is forecast across the eastern Carolinas and Florida Peninsula. Following the heavy to excessive rainfall during early June, an extended period of dry weather is likely along the Gulf Coast. Seasonal dryness is forecast across the Southwest and California, while occasional light precipitation occurs across the Pacific Northwest.
The CPC 6-10 day outlook (June 16-20) indicates increased chances of above normal temperatures extending from the Great Plains northeast to the Great Lakes and New England with below normal temperature most likely across the northern Rockies. A large area with increased chances of below normal precipitation covers most of the Great Plains, Mississippi Valley, Corn Belt, and Gulf Coast States. A slight tilt toward above normal precipitation is limited to the mid-Atlantic, South Florida, and parts of the Pacific Northwest and northern Rockies. Above normal temperatures are favored throughout Alaska along with slightly elevated probabilities of above normal precipitation.