Drought coverage expanded to include more than a half of the contiguous U.S. during the 2021-2022 winter. This drought expansion is typical for a La Niña winter.
The highest forecast confidence exists across the West where persistence is likely due to below average snowpack for many areas and an increasingly dry climatology. Despite heavy precipitation forecast across the central Rockies, central to southern Great Plains, and lower Mississippi Valley during mid to late March, the likelihood of above normal temperatures and below normal precipitation during April-May-June supports persistence.
The monthly and seasonal outlooks favor development for parts of Arizona along with the central to southern Great Plains. Drought is expected to persist across the northern Great Plains and western Corn Belt, despite an increasingly wet climatology later in the spring. Most of these areas had a lack of snowfall this past winter.
Also, above normal temperatures and below normal precipitation are favored for Nebraska and South Dakota during April-May-June.
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Prospects for improving drought conditions increase to the east across the upper Mississippi Valley where snowfall was heavier this past winter. Long-term drought is most likely to persist for northern New England, while short-term drought is favored to end across the Mid-Atlantic and Southeast by the end of June.
Later in the spring and heading into the summer, any prolonged periods of above normal temperatures and below normal precipitation will be closely monitored for rapid drought onset across the central and eastern U.S.
Drought improvement or removal are favored across Hawaii. However, if this doesn’t occur during April, improving conditions are less likely later this spring. Persistence is forecast for the small drought areas in southern Puerto Rico, while Alaska is likely to remain drought-free through the end of June.
Forecast confidence for the Western Region is high except for eastern Montana, where confidence is low.
- Broad-scale persistence is the likely outcome throughout the West based on below average snowpack for many areas and an increasingly dry climatology during the next 3.5 months.
- Also, the water-year-to-date (Oct 1, 2021 to Mar 15, 2022) precipitation is running below average for nearly all areas west of the Continental Divide except for parts of the Pacific Northwest.
- The AMJ outlook, favoring above normal temperatures and below normal precipitation, supports development for parts of Arizona. Although the April outlook depicts slightly elevated probabilities for above normal precipitation across Oregon and Washington, precipitation is not expected to be enough next month to result in wide scale improvements given the below normal snowpack throughout most river basins.
- Any improvement for the Southwest is unlikely until later in the summer with the onset of the monsoon.
- Based on the lack of snow cover across central and eastern Montana heading into the early spring and the absence of a strong wet signal at any time scale, persistence is forecast for Montana.
- Forecast confidence is low though, considering that precipitation typically increases throughout the northern High Plains during May and June.
Forecast confidence is low for the High Plains Region.
- Since early February, drought expanded or intensified across the central Great Plains while the eastern half of North Dakota became drought-free.
- Despite an increasingly wet climatology during AMJ, the seasonal outlook calls for enhanced probabilities of below normal precipitation and above normal temperatures which supports broad-scale persistence across ongoing drought areas of the northern to central Great Plains.
- Development is expected across eastern Kansas, but it may be delayed due to heavy rainfall forecast during mid to late March.
- Improvements are expected for parts of Colorado and south-central Wyoming during late March based on near average snow water equivalent values and predicted 7-day precipitation amounts of more than 1 inch, liquid equivalent.
- However, the monthly and seasonal outlooks favor below normal precipitation and above normal temperatures. These 30 to 90-day outlooks imply that any drought improvements are most likely to be brief followed by worsening conditions later this spring.
- Also, above normal temperatures during the spring could result in rapid snow melt which is typically less favorable for soil moisture recharge and drought improvement.
- For these reasons, drought persistence is the most likely outcome by the end of June across Colorado and Wyoming.
Forecast confidence for the Southern Region is moderate for the southern Great Plains but low for the lower Mississippi Valley.
- Drought expanded and intensified across the southern Great Plains and lower Mississippi Valley this past winter, driven by La Niña. Soil moisture is below the 10th percentile for much of southern Arkansas, Louisiana, western Oklahoma, and Texas.
- As of March 16, the Weather Prediction Center’s 7-day precipitation forecast depicts 1 to 3 inches of rainfall across eastern parts of Oklahoma and Texas along with the lower Mississippi Valley. This heavy rainfall during the next week complicates the seasonal drought outlook and lowers forecast confidence, as improvement is anticipated by late March.
- However, ensemble means suggest that this is likely to be a transient wet period with anomalous 500-hPa ridging and drier than normal conditions favored to return by the end of March.
- The drought persistence and development forecast for the southern Great Plains and lower Mississippi Valley are consistent with the monthly and seasonal outlooks, calling for enhanced probabilities of above normal temperatures and below normal precipitation.
- Also, water demand and evapotranspiration rates will be increasing as temperatures warm during AMJ, making any widespread drought improvement unlikely.
Forecast confidence is moderate for the Midwest Region.
- The eastern Corn Belt and Ohio River Valley remain drought-free with soil moisture above the 70th percentile and 90-day precipitation averaging 125 to 200 percent of normal. These wet conditions are consistent with La Niña during the winter.
- Farther to the northwest across northern Illinois, Iowa, and southern Wisconsin, drought indicators vary. Drought persistence is favored for western and northern Iowa where a wet signal is weaker at all time scales. Also, the seasonal outlook depicts enhanced probabilities of above normal temperatures for Iowa.
- Based on 7-day precipitation forecasts and a stronger wet signal at the monthly and seasonal time scales, improvement or removal is favored for southeast Iowa, northern Illinois, and much of southern Wisconsin.
- Heavier snowfall amounts this winter across northern Wisconsin and northeastern Minnesota increase the chances for soil moisture recharge as the snowfall melts in the coming weeks.
- In addition, the climatology becomes increasingly wet across the upper Mississippi Valley during AMJ. Therefore, improvement or removal is forecast for northern Wisconsin and northeastern Minnesota.
Forecast confidence is low for the Southeast Region.
- Short-term drought developed across parts of Florida and the Coastal Plain of the Southeast during late February into the beginning of March, but recent heavy rainfall resulted in improvements for parts of Florida.
- Periods of beneficial rainfall are forecast to continue during the next week to ten days across much of the Southeast.
- The climatology becomes increasingly wet during June across Florida and near coastal areas of Georgia and the Carolinas as sea breeze convection develops. These factors support removal either in the short-term or by the end of June, but conditions are expected to be quite variable during the next 3.5 months.
- Any prolonged periods of heat and dryness along with increasing water demand could lead to rapidly developing drought.
Forecast confidence is moderate for the Northeast Region.
- Persistence is favored for the long-term drought area across western Maine and northern New Hampshire, based on the lack of a wet signal at the seasonal time scale and late spring/early summer is an unfavorable time of year for soil moisture recharge.
- Since drought indicators are somewhat marginal across southeastern Pennsylvania and southern New Jersey and mid to late March is forecast to be relatively wet, removal is most likely for those ongoing drought areas.
Forecast confidence is high for Alaska.
- Based on above normal snow water equivalent values throughout the rivers basins of Alaska and an increasingly wet climatology by June, Alaska is likely to remain drought-free.
Forecast confidence is low for Hawaii.
- Following a period of dryness during February through the beginning of March, short-term moderate to severe drought was expanded throughout the Hawaiian Islands.
- There is excellent agreement among the inputs to the North American Mult-Model Ensemble for above normal precipitation during April. Therefore, removal is favored across the Hawaiian Islands.
- If drought does not end by early May, chances for that to occur are likely to decrease as the climatology becomes drier later in May and June.
- Forecast confidence is low due to recent dryness which is atypical of La Niña.
Forecast confidence is low for Puerto Rico.
- Persistence is most likely for the small moderate drought areas across southern Puerto Rico, due to the lack of a wet signal during the remainder of March and the North American Multi-Model Ensemble favoring below normal precipitation at the seasonal time scale. Since May is one of the wetter months of the year, development is not forecast at this time.
