Over the Plains and central lands, hot, dry air flow near the front will drain moisture from the ground, raising concerns of fast-moving fires Monday into Tuesday. Red flag warnings for dangerous fire weather extend from the U.S.-Mexico border in Texas to outside Chicago, affecting nearly 20 million people.
Ahead of the front, abnormally warm and humid air pushing north into the Midwest will allow thunderstorms to develop on Tuesday, a few of which could produce large hail, damaging winds and two tornadoes. The area from Chicago to Detroit and south toward St. Louis is most at risk.
Behind the front, temperatures drop. That's why winter storm warnings and winter weather warnings cover the high terrain of the Mountain West, affecting more than 5 million people. National Weather Service It is a warning A vast area from Nevada and Montana to Colorado and Wyoming is expected to see “widespread mountain snow, high winds and hazardous travel.” As temperatures drop eastward through Tuesday, snow will also spread to North Dakota and northern Minnesota, where winter weather alerts are in effect.
Most of the active weather will be around the front that extends from northern California to North Dakota. It is expected to advance to the east and south during the middle of the week before exiting the east coast.
Before then, record-defying warmth will spread north. Behind it, cold, dry air with wind chills will bump southward during a retreat in the jet stream.
Colliding air masses will spark severe thunderstorms over the Midwest along and ahead of the cold front, while swirling moisture on the back side of the storm system will produce snowfall. Dry air in the “dry slot” of the storm system — or the wedge of dry air rising from the southwest — will sweep across the Plains. This will create fire-friendly weather.
Risk of severe thunderstorms Tuesday in the Midwest
Thunderstorms, some severe, will develop along and ahead of the cold front Tuesday in the Midwest. They will have a limited fuel supply, but ample wind dynamics. As the jet stream cuts at the top, there is a dramatic change in wind speed and/or direction with height, known as shear, he will come.
A few rotating supercells will be possible, with the risk of large hailstones, damaging winds, and tornadoes.
- Level 2 out of 5 A slight risk of severe storms has been identified by the Weather Service's Storm Prediction Center. It extends from south of Milwaukee to Detroit and south toward extreme southern Illinois and eastern Missouri. chicago; Springfield, Illinois; Indianapolis; Toledo; And all of St. Louis is in the area to watch.
- There is an increased possibility that it is level 3 out of 5 An increased risk of severe weather will be shown in the later forecast, most likely from Chicago to the east. This is where the warm front rising north will add a little extra rotation, helping the storms rotate.
Snow falls due to the wind on the western mountains and northern plains
An annoying mix of snow and wind will mean travel problems throughout the Mountain West through Tuesday, spreading to the northern Plains.
Blizzard conditions continue over the Oregon and Washington Cascades, where snowfall rates of 1 to 2 inches per hour will halt travel through mountain passes. Totals of 2 feet or more are possible in the Cascades above the rain and snow line, with up to 4 feet on the highest mountain peaks.
Moderate to heavy snow will move into the Great Basin and Central Rocky Mountains, and come with winds of 50 to 65 mph in higher terrain. This will lead to blizzard conditions and nearly impossible travel. Much of the higher terrain has a 70 percent or more change in seeing accumulations of a foot or more, the weather service writes.
Freezing air will break south behind the front, with temperatures dropping into the lows and single digits, even across the northern Plains. Strong winds and several inches of snow are expected to fall in eastern North Dakota and northern Minnesota on Tuesday.
Dangerous fire weather in the plains
As hot and windy weather moves northward ahead of the front, dangerous fire weather is already in place in West Texas, southeastern New Mexico, Oklahoma and Texas. That's where the Storm Prediction Center designated the “critical” risk for wildfires through Monday. A lower, but still significant, highland wildfire risk extends into Nebraska and Iowa.
For the plains, the main drivers of fiery weather are twofold:
- Temperatures are unusually warm, ranging from 20 to 30 degrees above average. That means 80s and 90s in eastern New Mexico and Texas, with 60s and 70s for the rest of the Plains — very unusual for February. Higher temperatures cause more moisture to evaporate from the ground, sapping moisture from plants and drying out the landscape.
- Slope winds, or the pulling of air from the top of the Rockies to a lower elevation over the plains. A belt of strong westerly winds associated with the jet stream mixes high at the surface, increasing strong westerly winds across the Rockies and western plains. When air descends from higher altitudes to lower altitudes, it is compressed, heated, and dried. This brings very low humidity levels.
A massive area of low relative humidity is expected to spread over the Plains on Monday afternoon, meaning the air will hold very little moisture. With westerly winds of 30 to 40 mph, any smoldering fires could spread very quickly.
“Exercise caution if engaging in activities that could result in a fire,” the weather service advised.
Farther east across the Corn Belt, severe to severe drought conditions will exacerbate fire risks.
Continued wildfire concerns will be an issue through Tuesday as well, especially across the High Plains.
Jason Samino contributed to this report.
