Heavy rain, flooding threaten US Southwest and Central Plains
The WPC maintains a risk of excessive rainfall and flash flooding this Thursday from New Mexico toward the plains, while a coastal low is developing in the Atlantic and threatens the eastern United States this weekend with strong winds, high waves, and storm surges. In the Northwest, a Pacific system will bring widespread rain and snow to the higher elevations of the Cascades.
Rain in Brooklyn, NY - Reference Image
The Weather Prediction Center (WPC) has issued a warning for excessive rainfall and a risk of flash flooding from the Southwest to the Central Plains, with a coastal storm forming that could bring strong winds and a storm surge to the East Coast over the weekend.
Flood risk in the Southwest and the Plains
An upper-level trough remains over the southwestern U.S., and a plume of tropical moisture is moving toward the central plains. This will lead to scattered showers and thunderstorms on Thursday, although the rain will be less widespread than in previous days. Atmospheric instability and short-wave disturbances will continue to generate thunderstorms with high precipitation rates.
The WPC maintains:
- A slight risk of excessive rainfall in New Mexico and parts of the southern and central plains, where the ground is already saturated.
- Marginal risk across much of the Four Corners region extending to the central plains, with locally intense rain.
On Friday, the band of moisture and instability will shift toward the Midwest, increasing rainfall rates and the risk of flash flooding from the Southwest and the Plains into the Midwest.
Scattered showers and thunderstorms are expected across the northern Plains and the Upper Midwest through early Saturday morning, as moisture continues to move eastward.
Coastal storm threatens the East Coast
An inverted trough will continue to bring scattered showers and isolated thunderstorms this Thursday in the Ohio/Tennessee Valley, the Mid-Atlantic, and coastal areas.
By the end of the week, a strong coastal low will intensify over the western Atlantic. This will generate a strong marine flow from the mid-Atlantic to New England over the weekend.
Rain will begin in coastal areas on Friday and become heavier and more persistent from Friday through Saturday. Rainfall totals may be locally high, especially in southern New England and eastern Massachusetts.
Also expected:
- Gusts exceeding 45 mph.
- Moderate to severe coastal flooding.
- High waves, rip currents, and beach erosion.
The WPC recommends checking its updated key messages on its website.
Rain and possible Snow in the Pacific Northwest
A strong shortwave trough from the Pacific will deepen as it moves into the Pacific Northwest late Thursday.
The combination of sufficient moisture and frontal forcing will trigger a period of widespread rain in Washington and Oregon, gradually extending northward into the Rockies on Friday.
With the arrival of colder air, snow accumulations could occur at higher elevations in the northern Rockies and the Cascades.
Context and recent background
Quantitative precipitation forecasts estimate accumulations of 3–4 inches (76–102 mm) across large areas of New Mexico, with localized maximums of up to 5 inches (127 mm) and extreme scenarios of 6–8 inches (152–203 mm) in some areas.
The current situation represents a continuation and eastward shift of that same multi-day rain event.
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