Drought of varying intensity continues to affect much of the West and Great Plains. Given the low snowpack and increasingly dry climatology, forecast confidence of persistence is highest for California. Persistence across the Great Basin, central to southern Rockies, and Southwest is consistent with the updated April outlook favoring below-normal precipitation.
This favored dryness along with elevated probabilities for above-normal temperatures supports development across Arizona by the end of April. Broad-scale persistence is the most likely outcome for the Great Plains with the entrenched drought conditions and higher water demand later in the month. However, forecast confidence is low for this region due to an increasingly wet climatology.
Following a wet winter, slow improvement of long-term drought occurred across the upper Mississippi Valley during March. Additional drought improvement or removal are expected by the end of April with the updated monthly outlook favoring above-normal precipitation.
The one exception is southern Wisconsin and northern Illinois where larger long-term precipitation deficits exist. Excessive wetness continues to affect the eastern Corn Belt.
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Drought improvement or removal are forecast for parts of the lower Mississippi Valley and Georgia due to recent heavy rainfall and the likelihood of additional rainfall during the first week of April.
Conversely, drought persistence and development are favored for southern Florida where any widespread improvement is unlikely until June. Elsewhere, April rainfall is not expected to be enough for drought removal across the Southeast, Mid-Atlantic, or western Maine.
Persistence is forecast for much of the Hawaiian Islands given the dry initial conditions. However, a wetter pattern during early to mid-April is expected to provide drought relief to Oahu. Persistence is forecast for the small drought areas in southern Puerto Rico, while Alaska is likely to remain drought-free through the end of April.
Forecast confidence for the Western Region is high except for Arizona where confidence is moderate due to uncertainty on the timing of development.
- Persistence is likely for the West based on below average snowpack for many areas and an increasingly dry climatology during April. Also, the water-year-to-date (WYTD), from Oct 1, 2021 to Mar 31, 2022, precipitation is running below average for nearly all areas west of the Continental Divide.
- WYTD precipitation averaged less than 50 percent of normal for southeast Oregon, southern Nevada, and southern California. Much above normal temperatures during late March resulted in an early and rapid melting of nearly a third of the snowpack across the Sierra Nevada Mountains.
- The April outlook favors above normal temperatures and below normal precipitation for California, the Great Basin, and Southwest.
- Although recent precipitation may delay development across the abnormally dry (D0) areas of Arizona, the strong signal for warmth during April favors development by the end of the month.
- Precipitation may begin to increase across the High Plains of Montana by mid-April as ensemble means depict an amplifying 500-hPa trough over the northwestern CONUS. However, given that soil moisture is below the 10th or even 5th percentile, any precipitation during April is unlikely to result in widespread improving drought conditions by the end of the month.
Forecast confidence is low for the High Plains Region.
- During March, above-normal precipitation resulted in improving drought conditions across the Colorado Rockies and adjacent High Plains.
- North-central Colorado is expected to remain drought-free through the end of April due to additional precipitation during early April.
- Elsewhere, across Colorado and Wyoming, persistence is the most likely outcome with the April outlook favoring below-normal precipitation for these two states.
- The northern and central Great Plains experienced either steady or worsening drought conditions during March.
- Forecast confidence for these areas remains low as precipitation typically begins to increase later in April.
- The updated April outlooks slightly favor below-normal precipitation for most of Kansas and Nebraska with equal chances of below, near, or above normal precipitation forecast for the Dakotas. The ensemble means continue to depict an amplifying 500-hPa trough upstream by mid-April which could provide beneficial rainfall and pockets of drought amelioration for the northern to central Great Plains.
- However, broad-scale persistence is the most likely outcome by the end of April.
Forecast confidence is moderate for the Southern Region.
- During the latter half of March, much of northern Louisiana and west-central Mississippi received more than 3 inches (locally 5 inches) of rainfall.
- Based on this recent wetness and heavy rainfall at the end of March, improvement or removal of drought is forecast for parts of the lower Mississippi Valley.
- Persistence or development is favored for much of the southern Great Plains, Rio Grande Valley, and New Mexico since the updated April outlook calls for enhanced probabilities of above normal temperatures and below normal precipitation.
- However, parts of eastern Texas are expected to remain drought-free through the end of April due to above-normal precipitation during the past 30 to 60 days.
- Due to the antecedent dryness, enhanced winds associated with surface low development across the High Plains may result in blowing dust.
Forecast confidence is high for the Midwest Region.
- Excessive wetness continues to affect the eastern Corn Belt where soil moisture remains above the 70th percentile. Recent wetness along with snow melt prompted drought improvement across the upper Mississippi Valley since early March.
- Precipitation tools at all time scales through April favor a continuation of a wet pattern for the Midwest.
- During the first week of April, the 7-day WPC forecast depicts 0.5 to 1.5 inches of precipitation. By mid-April, an amplifying 500-hPa trough is forecast to develop upstream which would result in a stormy pattern with periods of enhanced precipitation.
- Removal or improvement is forecast for most of the lingering drought areas of the Midwest. However, a small area of persistence is expected for southern Wisconsin and northern Illinois where long-term precipitation deficits are the largest.
- Forecast confidence is high that the eastern Corn Belt remains drought-free through the end of April.
Forecast confidence is moderate for the Southeast Region.
- Short-term drought developed across parts of Florida and the Coastal Plain of the Southeast during late February into March. Although beneficial rainfall occurred at the end of March and is likely to continue through the first week of April, ensemble means remain consistent that a 500-hPa pattern change occurs during the second week of April.
- This pattern change, featuring a building 500-hPa ridge over the Southeast, would favor a return of drier and warmer conditions by mid-month.
- Despite the wet start to the month, drought removal is limited to areas of Georgia that are receiving the heaviest rainfall at the end of March and are also most likely to have more than 1 inch of rainfall on April 5 and 6.
- April is a relatively dry time of year for the areas currently designated with short-term drought and persistence is favored for the remainder of the Southeast. Another factor supporting persistence is the increasing water demand as temperatures warm later in the month.
- During early April, the heaviest rainfall is forecast to remain generally north of the southern Florida Peninsula where persistence and development are favored.
Forecast confidence is moderate for the Northeast Region.
- Persistence is favored for the long-term drought area across western Maine since precipitation amounts during April are not expected to offset the large 180-day precipitation deficits.
- 28-day streamflows and soil moisture are below the 30th percentile across much of the Mid-Atlantic which would typically set the stage for additional development.
- However, due to near to above normal precipitation and the lack of above-normal temperatures early in the month, widespread development is unlikely at this time.
Forecast confidence is high for Alaska.
- Based on above normal snow water equivalent values throughout the river basins of Alaska and an increasingly wet climatology, Alaska is likely to remain drought-free.
Forecast confidence is low for Hawaii.
- During late March, enhanced trade winds resulted in an increase in rainfall across Hawaii. This helped to ease drought conditions on windward sides of the Hawaiian Islands, but leeward areas largely missed out on the recent rainfall.
- The GFS and ECMWF ensemble means are depicting a 500-hPa trough amplifying into the subtropics of the central Pacific during early to mid-April.
- Based on this evolving pattern and initial conditions, improvement or removal are most likely on Oahu. For the remainder of the Hawaiian Islands, persistence is favored given the unusually dry conditions following a La Niña winter and the wet season is coming to an end.
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 next couple of weeks and these are designated as long-term drought.