Drought Monitor Logs Broad One-Category Gains Across Southwest

More than 1 inch of additional precipitation between Oct. 27 and Nov. 2 triggered a broad one-category improvement across the Southwest and Great Basin, according to the latest U.S. Drought Monitor, ending short-term drought in New Mexico, nearly all of Minnesota, and the Desert Southwest.

The monitor, released in early November and written by Brad Pugh of the Climate Prediction Center at NOAA, credited a persistently wet fall across the southwest quarter of the contiguous United States. Short-term drought has ended for those regions. Long-term drought of varying intensity still carries a designation across parts of the same areas, a distinction that matters for growers weighing soil moisture recharge against multi-year hydrologic deficits.

The U.S. Drought Monitor is 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.

What changed in the South?

Remnants of Hurricane Vance, which formed in the East Pacific, delivered heavy rainfall to western and central Texas. A one-category improvement covered roughly the areas receiving more than 1 to 1.5 inches, with the standardized precipitation index at various time scales factored into the analysis.

New Mexico's unusually wet fall required a broad one-category improvement statewide, and Pugh noted that additional upgrades may follow in subsequent weeks to align the map with long-term metrics. Near or more than 1 inch of precipitation supported improvements across the western third of Oklahoma.

Because that rain fell on Nov. 2, near the end of the monitoring window, a fuller assessment of the latest metrics could extend improvements to a greater share of Oklahoma in next week's map.

Severe, extreme and exceptional drought coverage across Arkansas, Louisiana, Mississippi and Tennessee remained generally consistent with the standardized precipitation evapotranspiration index at multiple time scales and soil moisture indicators — a signal that the Mid-South's dry pattern has not broken.

How did the Midwest and Plains fare?

Widespread D2 to D3 drought persists across southern Missouri, and 60- to 90-day SPEI values plus soil moisture readings supported an expansion of those categories across the southern third of the state. Rising 30- to 60-day precipitation deficits, declining soil moisture and the NDMC short-term blend drove a one-category degradation across Illinois and Missouri.

Minnesota moved the other way. Unusually heavy precipitation for early November — widespread amounts of 1.5 inches or more — produced a broad one-category improvement across much of the state, ending short-term drought nearly everywhere in Minnesota.

In the High Plains, widespread precipitation of 0.5 to 2 inches, locally higher, brought one-category improvements to 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.

Out West, a low-pressure system tracking at an unusually low latitude for the season delivered anomalously wet conditions to the Desert Southwest over the Halloween weekend. Precipitation of 0.5 to 1 inch, locally more, brought smaller improvements to parts of Montana.

Drought expanded and intensified elsewhere: parts of the Lower to Middle Mississippi Valley, the Ohio Valley, the Mid-Atlantic and New England all deteriorated, while Florida's drought coverage continued its late-summer and fall decline.

What does the forecast hold?

A drier, more typical multi-day period from Nov. 5 to 9 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 one inch — from the coastal Mid-Atlantic north to southeastern New England, and heavy precipitation possible in the Lower Rio Grande Valley at 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 increasingly threatens the West Coast. The National Weather Service's 6- to 10-day outlook, valid Nov. 10-14, shows better than a 60 percent chance of above-normal precipitation for much of California and the Pacific Northwest, with above-normal precipitation also favored across the Great Basin and Southwest. Below-normal precipitation is more likely across the northern to central Great Plains and Midwest, while enhanced Pacific flow strongly favors above-normal temperatures for nearly all of the contiguous U.S. — a pattern typical of a strong El Niño during fall.