Drought Monitor: Wet Fall Brings Broad Improvements to Southwest

More than 1 inch of additional precipitation from Oct. 27 to Nov. 2 triggered a broad one-category improvement across the Southwest and Great Basin, ending short-term drought in the region even as long-term drought designations persist.

The latest U.S. Drought Monitor, jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the U.S. Department of Agriculture and the National Oceanic and Atmospheric Administration, shows the wet fall continuing to reshape the national drought map. A positive shift in long-term metrics since September supported the Southwest improvements.

What changed in the South?

The remnants of Hurricane Vance, which formed in the East Pacific, brought drought-easing rainfall to western and central Texas. One-category improvements covered roughly the areas that received more than 1 to 1.5 inches, with the standardized precipitation index at various time scales also weighed.

New Mexico required a broad one-category improvement after an unusually wet fall. Additional improvements may follow in subsequent weeks to align designations with long-term metrics. The short-term drought has ended for New Mexico.

Near or more than 1 inch of precipitation supported improvements across the western third of Oklahoma. Because that rain fell on Nov. 2, forecasters say a greater coverage of Oklahoma could improve next week once a full assessment of the latest metrics is complete.

Severe, extreme and exceptional drought coverage across Arkansas, Louisiana, Mississippi and Tennessee remains generally consistent with the standardized precipitation evapotranspiration index at various time scales and soil moisture indicators.

Drought coverage continued its late-summer and fall decline across Florida. In contrast, drought expanded and intensified across parts of the Lower to Middle Mississippi Valley, Ohio Valley, Mid-Atlantic and New England.

How did the Midwest fare?

Widespread D2 to D3 drought continues across southern Missouri. Sixty- to 90-day SPEI values and soil moisture indicators supported an expansion of those categories across the southern third of the state.

Increasing 30- to 60-day precipitation deficits, declining soil moisture and the NDMC short-term blend drove a one-category degradation across Illinois and Missouri. Conversely, unusually heavy precipitation for this time of year — widespread amounts of 1.5 inches or more — brought a broad one-category improvement to much of Minnesota. Short-term drought has ended for nearly all of Minnesota.

High Plains and West see gains

Widespread precipitation of 0.5 to 2 inches, locally more, produced one-category improvements across the western third of Colorado and parts of the Northern to Central Great Plains. Recent precipitation and what analysts call a "convergence of evidence" supported discontinuing D3, extreme drought, across most of the Nebraska Panhandle.

In the West, a low-pressure system at an unusually low latitude for this time of year delivered anomalously wet conditions to the Desert Southwest over the Halloween weekend. Short-term drought has ended for the Southwest and Great Basin. Despite multiple short-term metrics running on the wet side, long-term drought of varying intensity persists across parts of these areas.

Precipitation of 0.5 to 1 inch, locally more, during the past week led to small improvements for parts of Montana.

What should farmers watch next?

A much drier multi-day period from Nov. 5 to 9, more typical of fall, is forecast for a majority of the lower 48 states. A cold front will trigger wet weather along the East Coast, with the heaviest amounts — more than 1 inch — from the coastal Mid-Atlantic north to southeastern New England. Heavy precipitation may also strike the Lower Rio Grande Valley along the tail end of the front. The coastal Pacific Northwest is the only other area expected to receive significant precipitation.

By mid-November, an atmospheric river has an increasing chance of affecting the West Coast. The National Weather Service's 6- to 10-day outlook, valid Nov. 10-14, shows a greater than 60 percent chance of above-normal precipitation for much of California and the Pacific Northwest.

Above-normal precipitation is also favored across the Great Basin and Southwest. Below-normal precipitation is more likely across the northern to central Great Plains and Midwest. The enhanced Pacific flow strongly favors above-normal temperatures for nearly all the contiguous U.S. — a pattern typical of a strong El Nino during fall.

Brad Pugh of CPC/NOAA authored the outlook. Growers in Oklahoma and New Mexico should watch subsequent Drought Monitor releases, as further one-category improvements remain possible once late-October and early-November rainfall is fully absorbed into the long-term metrics.