Wednesday could be a historic weather day in Iowa as a windstorm is expected to bring powerful gusts and thunderstorms to the state in the afternoon andevening.
When will severe weather hit Iowa?
South to southwest winds from 30 to 40 mph will enter Iowa. Gusts of 60 to 70 mph are possible Wednesday evening, according to the National Weather Service.
As a low pressure system moves across the Central Plains to the Great Lakes temperatures will be 25 to 40 degrees above average.
Live updates:Iowa preparing for high winds, thunderstorms, possible tornadoes
Severe thunderstorms are expected to hit Iowa Wednesday evening.
Rod Donavon, a lead meteorologist at the National Weather Service in Des Moines, said on Twitter that Wednesday could be a "historic day in Iowa Weather."
All but one Iowa county under high wind warning
High wind warnings were issued from eastern Arizona and New Mexico to Michigan as a powerful windstorm moves northeast across a large swath of the U.S.
Every Iowa county except for Lee County in southeast Iowa was under a high wind warning Wednesday. Lee County was in a high wind watch, along with parts of Illinois and Missouri.
- In southwest Iowa, the high wind warning was in effect from noon to 9 p.m. Wednesday.
- Central Iowa areas including Des Moines were under a high wind warning from noon Wednesday to midnight Thursday.
- Eastern Iowa areas, including Davenport, wereunder a high wind warning from 3 p.m. Wednesday to 6 a.m. Thursday.
- Red flag warnings werealso in effect in southwest Iowa and southeast Nebraska because of dangers posed by fires which may start.
When are highwinds expected?
Winds are expected to gradually increase throughout the day.At 11 a.m. in Des Moines sustained winds could be 20 mph and gusts couldbe 28 mph, according to the NWS. By 5 p.m. sustained winds may be 30 mph withgusts up to57 mph. Peak winds are expected hit at 8 p.m.with sustained winds of 35 mphand gusts of 70 mph.
Power outages expected, travel could be difficult
Damaging winds may blow down trees and power lines, according to the NWS. Power outages are expected. Warmtemperatures and low humidity can "contribute to extreme fire behavior," the NWS office in Omahasaid in a warning.
Travel may be difficult, especially for high profile vehicles like semitrailers and school buses.
"People should avoid being outside in forested areas and around trees and branches," a high wind warning from the NWS said."If possible, remain in the lower levels of your home during the windstorm, and avoid windows. Use caution if you must drive."
Which schools are closing early?
Many school districts in the Des Moines area announced plans to close early because of the storm.
More:These central Iowa schools plan early dismissals due to high wind warning on Wednesday
There could be thunderstorms, tornadoesin December?
Yep.
Thunderstorms are expected to move rapidly across central Iowa from 4 p.m. to 8 p.m.Wednesday. Damaging winds may enhancestrong non-thunderstorm winds, according to the NWS.
"The primary severe weather threats will be damaging winds and a few tornadoes," the NWS said in a forecast."With non-thunderstorm winds already gusting from 60 to 70 mph, winds in thunderstorms could reach 80 mph or more."
The greatest chances for severe weather are in northern Iowa and southern Minnesota areas including Mason City, Fort Dodge, Carroll and Ames, which all have moderate risks of severe thunderstorms, according to the NWS.Atlantic, Des Moines and Spencer all have enhanced risks of severe weather.
Council Bluffs, Sioux City and Iowa City all have slight risks of severe weather. Lyon County in extreme northwest Iowa, Burlington and Davenport all have marginal risks for severe weather.
How do the 2020 derecho wind speeds compare with Wednesday's forecastwinds?
While the wind gusts could be damaging, they aren't expected to reach the level of the derecho that swept through Iowa in August 2020.
Gusts from a derecho can top 100 mph, and last year's derecho in Iowa did just that. There were reports of gusts over 100 mph in last year's storm, including a gust of 130 mph near Cedar Rapids. Wind gusts around Des Moines were reported between 70 and 80 mph, according to the weather service.
The weather service classifies storms that have sustained winds of at least 58 mph and leave a path of damage at least 250 miles long qualify as derechos.
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Philip Joens covers breaking news for The Des Moines Register. He can be reached at 515-443-3347at pjoens@registermedia.com or on Twitter @Philip_Joens.
