PIERRE, S.D. (AP) — The Latest on severe weather impacting the central U.S. (all times local):4:58 p.m.Colorado Gov. Jared Polis has activated the National Guard in case troops are needed to rescue stranded motorists as they did during last month's blizzard.Guard officials said Wednesday that 50 soldiers and 24 vehicles will be positioned in the eastern part of the state, including vehicles with tank-like tracks for negotiating deep snow.The Colorado Department of Transportation says highway closures are likely with a blizzard warning in place through Thursday morning.The March blizzard paralyzed many of the same areas that are under the current warning.Troops searched through the night and rescued 75 people and two dogs from vehicles, mostly in four counties southeast of Denver.3:47 p.m.State officials in flood-ravaged Nebraska are bracing once again for a major snowstorm that threatens to disrupt travel and endanger motorists.The state Department of Transportation closed Interstate 80 in western Nebraska Wednesday afternoon from the intersection of Interstate 76 to the Wyoming border.The Nebraska State Patrol is sending additional troopers into the state's panhandle to help with any storm-related needs.Gov. Pete Ricketts announced that he has extended five weather-related executive orders until May 15 to help communities gain fast access to the state's emergency resources.Officials say it's too early to know whether the storm will lead to additional flooding in the state, which is still recovering from last month's record disaster___1:55 p.m.A storm bringing heavy snow and strong winds to several Rockies and Plains states is making travel difficult in many areas and impossible in others.Officials have closed Interstate 29 from Brookings in east central South Dakota to the North Dakota border. They say the stretch of I-29 between Brookings and Sioux Falls is likely to be closed later in the day, and conditions on I-90 across southern South Dakota are rapidly deteriorating.Transportation officials in Colorado say highway closures also are likely in that state. Local governments, including in Denver and Cheyenne, Wyoming, and state government in the Denver area are closing offices early to give workers time to commute before conditions worsen.About half of the daily flights at Denver International Airport have been canceled.___12:17 p.m.A storm impacting Rockies and Plains states has met the scientific definition of what's commonly known as a "bomb cyclone." It's the second such blast to hit the region in less than a month.The weather phenomenon is difficult to explain in layman's terms. Essentially, air pressure drops rapidly and a storm strengthens explosively.Forecaster David Roth at the National Weather Service's Weather Prediction Center says what's more important than the scientific term is the impacts. He says this week's storm likely will be similar to the one that hit in mid-March. That one dropped heavy snow and led to massive flooding in the Midwest.Weather service meteorologist Mike Connelly in South Dakota says the latest storm could be "historic" in terms of widespread heavy snow. He expects some records to be set.___11:05 a.m.Flights, baseball and school classes are being canceled ahead of a looming spring blizzard in the Rockies.About 40 percent of Denver International Airport's daily flights have been scratched, most of them in the afternoon when rain is expected to turn into snow.The Colorado Rockies were supposed to play the Atlanta Braves at about that time but announced they are postponing the game until August.Blizzard warnings have been issued for the northern half of Colorado's heavily-populated Front Range region, including Denver, as well as the state's northeastern plains from noon through midday Thursday. Blizzard warnings also are posted for southeastern Wyoming, including Cheyenne, from Wednesday into Thursday.A few school districts canceled classes in Colorado and Wyoming but many decided to have a shortened day and cancel evening activities instead.___10:55 a.m.Strong winds associated with a weather system moving out of the Rockies and into the Plains are creating dangerous wildfire conditions in New Mexico and Texas.The National Weather Service says winds in excess of 50 mph (80.46 kph) will combine with low humidity and an unstable atmosphere to create critical fire conditions.Weather Prediction Center forecaster David Roth says wind gusts have already exceeded 60 mph (96.56 kph) in west Texas.Forecasters in New Mexico also say the winds will make travel difficult on north-south oriented roads such as Interstate 25, particularly for high-profile vehicles, and cause loose objects to become airborne.In southern New Mexico, the U.S. Army's White Sands Missile Range closed Wednesday because of high winds, with only emergency essential personnel told to report to work.___9:43 a.m.Blizzard warnings are posted from Colorado to Minnesota as a storm develops that could rival last month's bomb cyclone.The National Weather Service says up to 2 ½ feet (0.61 meters) of snow could fall in parts of eastern South Dakota and southwestern Minnesota.South Dakota Gov. Kristi Noem has closed state government offices in 52 counties. Numerous schools around the state have closed. Minnesota Gov. Tim Walz says "the National Guard stands ready" to rescue any stranded motorists.A bomb cyclone is an unusual weather phenomenon in which air pressure drops rapidly and a storm strengthens explosively. Last month's storm led to massive flooding in the Midwest that caused billions of dollars in damage.Forecasters say this week's storm will swell rivers again, but maybe not as much.