Latest Seasonal Assessment -
Drought coverage decreased slightly during the past four weeks, but within the drought areas, there were noteworthy changes in intensity. There was fairly broad expansion of D4 (exceptional drought, the most intense designation)from a small part of interior northwest Oklahoma into most of western Oklahoma, the eastern Texas Panhandle, and part of northeastern New Mexico. In the D4 areas in Oklahoma and Texas, fire danger was described as "historic" at times around mid-April, with high temperatures up to 101F accompanied by daytime relative humidities of 5 percent or lower and wind gusts frequently over tropical storm force. A few large wildfires scorched western Oklahoma and the eastern Texas Panhandle, consuming over a half-million acres in the Sooner State. Some locations in and near the Oklahoma and Texas Panhandles have received less than 0.5 inch of precipitation in the last half-year. Elsewhere, some drought intensification and expansion was noted in southwestern Texas, broad areas across the middle of the Four Corners States into adjacent Nevada and California, southern Florida, and parts of South Carolina and Georgia. Moderate drought persisted in the southern half of the Alaskan Panhandle.
Meanwhile, drought improved or was removed across much of California and northern Nevada, where a late-season storm system brought needed precipitation. Drought also continued to loosen its grip on the northern Plains, scattered parts of the central Rockies, the central Pacific Northwest, the eastern tier of the drought area in the central and southern Great Plains, and much of the Florida Panhandle.
In the south-central Great Plains and southern High Plains, where many areas are in extreme to exceptional drought (D3 to D4), May-July is one of the wettest times of the year. This period typically brings at least 35 percent of their annual precipitation, reaching around 45 percent in western Kansas. A storm system forecast to move through this region around April 20 is expected to drop 0.75 to 2.00 inches of precipitation in and around the Oklahoma and Texas Panhandles. In some locations, this would be 2 to 3 times the amount of that fell in the prior 6 months. Drought improvement is forecast across this region based on the short-term forecast and climatology.
Drought is expected to continue easing its grip on the northern Plains, where 45 to 65 percent of the annual precipitation typically falls during this three-month period. Seasonal precipitation increases are also expected to relieve drought conditions in southern Florida. There is less confidence in the forecast for drought improvement or removal farther north in the South Atlantic States.
To the west, May-July is a drier time of year in southern Texas and from the central and southern Rockies westward to the Pacific Coast, so there will not be as much opportunity for storm systems to bring relief to these areas. Drought should persist or worsen in these areas. Persistence is also expected in Oregon where subnormal precipitation is expected on all forecast time scales, with some expansion southward into areas where the region's low snowpack should have the most significant impacts as summer progresses.
Forecaster: Rich Tinker
Next Seasonal Outlook issued: May 17, 2018 at 8:30 AM EDT
Seasonal Drought Outlook Discussion