National observances for Memorial Day on May 25 face potential disruption across the eastern half of the United States due to forecasts of widespread showers and thunderstorms. The National Weather Service issued a forecast on May 24, indicating that much of the Central and Southeastern United States is at risk of severe weather on the national holiday.
Low pressure systems, combined with abundant moisture along a slow-moving front, are expected to generate wet and active weather. Multiple rounds of showers and thunderstorms are forecast for May 25, impacting regions from the Lower Mississippi Valley, Mid-South, and Southeast, extending through the Ohio Valley, Mid-Atlantic, and Northeast.
Threat to National Observances
More than 10 million people across the nation could face a level two out of five risk of severe thunderstorms. This risk zone includes parts of New Mexico, Texas, Florida, Georgia, Nebraska, South Dakota, and Minnesota. The heaviest swath of rainfall, carrying the potential for flash flooding, is specifically forecast to stretch from southeastern Louisiana into Tennessee and the Carolinas, threatening public safety and traditional gatherings.
Conversely, a high-pressure area is expected to maintain mostly dry and warmer-than-normal conditions across much of the Western United States. The hottest temperatures are anticipated in the desert valleys of California, Nevada, and Arizona, where highs could climb into the 100s early in the week. The Pacific Northwest, however, could see some precipitation as Memorial Day progresses, with showers possible and snow potentially falling in the highest elevations of the Cascades.
Worsening Environmental Conditions
The U.S. Drought Monitor, in its May 21 release, revealed a significant deterioration in environmental conditions, with the area of the country experiencing severe or greater drought having doubled over the last three months. This figure rose sharply from 22% to 44%, according to Alan Gerard, a retired federal meteorologist who publishes the Balanced Weather blog on Substack. Gerard noted that the Drought Severity and Coverage Index has reached 206, marking its highest point since 2012 and surpassing a summer-to-autumn drought recorded in 2023.
The forecast thunderstorms present a mixed blessing for parts of the South. While the region is in dire need of rain after months of drought, the rapid fall of lightning or excessive precipitation could create additional problems, including sparking fires or causing flash flooding. Flash flooding was already reported on May 24 in southeast Texas, specifically within the Houston and Galveston weather service region.
Public Safety Warnings Issued
On May 24, nearly 17 million people, spanning from Texas to West Virginia, were placed under a flood watch, highlighting the widespread nature of the impending risks. The weather service office in New Orleans reported via an X post on May 24 that Gulfport, Mississippi, had received 7.19 inches of rain over three days. Houma, Louisiana, saw 4.09 inches, and New Orleans reported slightly more than 3 inches during the same period.
Gerard also detailed on Substack that an upper-air pattern, referred to as an omega block, appears to be forming. This pattern involves a high-pressure area over parts of the Central United States and an active area to the south, which will draw on very moist air to produce rounds of thunderstorms characterized by "torrential downpours." In Maine, the weather service office in Gray issued a warning regarding dangerous, unseasonably cold waters that could mislead swimmers about the frigid temperatures. Water temperatures are only in the mid-50s across Sebago Lake and Lake Winnipesaukee, and similarly low in other lakes and rivers in the region. The weather service cautioned that falling off a boat when water temperatures are below 60 degrees can quickly lead to hypothermia. "Anyone on small boats, canoes, or kayaks should plan accordingly ... and use extreme caution," the weather service advised, underscoring the direct threat to citizens engaging in traditional holiday activities.