22 million at risk of flooding from Oklahoma to Pennsylvania; severe storms threaten South
The stormy weather pattern across much of the United States shows "no signs of abating over the next couple of days as we head into the weekend," the National Weather Service said Thursday.
Sodden California, which has already faced significant storms this week, including two tornadoes and a bomb cyclone, saw more snow and rain on Thursday.
A storm is also forecast to move across the southern tier of the nation later Thursday and into Friday, potentially leading to flooding and the threat of more tornadoes in some areas both days.
Rainfall of up to 5 inches is possible in some regions. Excessive runoff may cause flooding of rivers and streams, the weather service warned, and people who live in areas prone to flooding should be “prepared to take action.”
Here’s what you need to know:
Flood fears: Rain, thunderstorms to sweep from Oklahoma to Pennsylvania
A forecast of rain and thunderstorms prompted the weather service to issue a flood watch from Oklahoma to Pennsylvania on Thursday. In all, more than 22 million people live where a flood watch is in effect as of late Thursday afternoon.
In flood-prone West Virginia, Governor Jim Justice (R) on Thursday declared a "state of preparedness" for the state's 55 counties due to the heavy rain threat.
The storms will “become a significant concern” later Thursday, continuing through Friday for parts of the southern Plains, Mississippi Valley and the South, according to the weather service.
States under the flood watch include:
Severe storms, tornadoes threaten South
Storms could also turn severe in the South in the next couple of days. The weather service issued severe thunderstorm watches for portions of Arkansas, Missouri, Oklahoma and Texas through Thursday evening.
On Friday, the threat for severe weather intensifies and expands, as areas from Houston to Cincinnati should prepare for strong to severe thunderstorms, according to AccuWeather meteorologists.
The storms could include "strong tornadoes," along with damaging winds and large hail, the Storm Prediction Center said. Portions of Arkansas, Mississippi and Louisiana are in the highest risk zone on Friday.
Rainfall and flash flooding maps: Where NWS says risk is highest
Very heavy rainfall expected from Oklahoma into the Ohio River Valley over the next three days will mean the potential for flash flooding for many. Check https://t.co/VyWINDk3xP for the latest, local details – and remember:
Turn Around, Don't Drown. pic.twitter.com/zNmdaOCJgY
— National Weather Service (@NWS) March 22, 2023
'Springlike' warmth in the South and East
Elsewhere across the South and many areas of the East ahead of the big storm, very warm temperatures will be in place and many areas will see daytime highs well above average, according to the weather service. "Many areas of the Gulf Coast, Mid-South, and Southeast will see high temperatures well into the 80s through the end of the week, and thus very springlike," the weather service said.
A bomb cyclone in California
A bomb cyclone hit California in recent days, bringing heavy rain and strong winds, AccuWeather meteorologists said.
What’s a bomb cyclone? Bombogenesis, a term more commonly used by meteorologists, can happen when a cyclone “rapidly intensifies, or strengthens, over a 24-hour period,” according to the National Ocean and Atmospheric Administration.
Bombogenesis "can happen when a cold air mass collides with a warm air mass, such as air over warm ocean waters.”
The winds, rain and snow in California continued to prompt warnings and advisories in the state on Thursday.
WHAT IS A BOMB CYCLONE?A winter hurricane, explained.
A winter weather advisory is in effect in parts of northern California, which will extend into Friday. Snow accumulations of up to 10 inches is expected in western Plumas County and nearby areas.
In western Siskiyou County, in far northern California, a winter weather advisory is also in effect into Friday, and snow accumulations of up to a foot are expected at higher elevations. Winds could also gust up to 40 mph.
Winter storm warnings and winter weather advisories were also in effect in Oregon and Washington, where heavy snow was forecast.
In central California, storms were responsible for at least five deaths in the Bay Area in recent days, most from falling trees. In addition, a rare tornado hit a Los Angeles suburb on Wednesday, injuring one person and damaging several buildings.
It was the second tornado to hit the state in the past two days, the weather service in Los Angeles said.
An Amtrak commuter train with 55 passengers struck a downed tree and derailed near Port Costa, California, on Tuesday. No one was injured in the incident.
Winter storm tracker
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Contributing: Jordan Mendoza, USA TODAY; The Associated Press
This article originally appeared on USA TODAY: US weather: Millions at risk of floods; flash flooding maps from NWS