Another surge of cold air across the western United States will collide with tropical moisture from the Gulf of Mexico, perhaps including some from the former Hurricane Otis, allowing a storm to develop over the central U.S. this weekend. AccuWeather meteorologists expect a zone of drenching rain to expand over the region, as a swath of snow and ice unfolds on the northwestern flank, bringing the first wintry precipitation of the season to some locations.
The new zone of wintry precipitation will follow an outbreak of cold air and rounds of heavy snow from the interior Northwest to the northern Rockies and northern Plains into Thursday night. As the first storm unleashing the cold and snow departs, the atmosphere will reload from Friday to Friday night.
Then, a plunge in the jet stream over the West will allow cold air to blast across the Colorado Rockies on Saturday and the High Plains of northeastern Colorado and southeastern Wyoming to southern Minnesota and northern Wisconsin from Saturday night to Sunday.
“As the pattern evolves, many areas over the Plains and Midwest will experience the coldest air of the season so far this weekend to early next week,” AccuWeather Senior Meteorologist Dave Dombek said.
As the storm evolves, snowfall will occur across a nearly 1,000-mile-long stretch of the U.S. from the central Rockies to near the Great Lakes region this weekend.
The setup will bring the Denver metro area its first widespread accumulating snow of the season. Accumulations around Denver will range from 1-3 inches to the east of the city to 3-6 inches in the foothills to the west.
The storm is likely to bring a general 6-12 inches of snow over the Colorado Front Range. Along the higher east-facing slopes of the Colorado Rockies, there is an AccuWeather Local StormMax™ of 24 inches. The Denver area averages about 5 inches of snow in October, and most of that snow tends to fall in one or two storms.
Airline delays are likely and flight cancellations are possible at Denver International Airport by Sunday.
Motorists should anticipate deteriorating travel conditions across the central Rockies to the central High Plains and perhaps part of the Upper Midwest on Saturday night and Sunday. Road conditions may vary from wet to slushy to snow-covered in this zone along portions of Interstates 25, 29, 70, 76 and 80.
Farther to the south and east, where the air will not be cold enough for snow, rain will expand from central Texas and portions of the southern Plains through the middle Mississippi and Ohio valleys this weekend.
The rain will fall on some areas that were already drenched by rain several days this week. Around 1 inch to 4.50 inches of rain had been measured from Monday through Wednesday morning in the zone from central Texas to eastern Kansas. The first storm will continue to bring beneficial moisture where widespread drought conditions exist into Thursday night.
More rain poured down on the Dallas metro area on Wednesday night. A general 4-6 inches of rain fell with locally higher amounts in 12 hours. Additional rain will fall in central Texas on Thursday.
As the weekend storm’s rain falls over some of the same areas saturated this week, runoff may significantly boost water levels along area streams and rivers. Additionally, some tropical moisture associated with former Category 5 Hurricane Otis may be pulled into part of the weekend storm over the central U.S.
Otis slammed ashore near Acapulco, Mexico, on Tuesday night with destructive winds, dangerous storm surge and flash flooding.
Even though Otis has dissipated over central Mexico, some moisture and energy may survive and reach the central U.S. this weekend in the form of a pocket of drenching rain and strong thunderstorms. AccuWeather forecasters say that the core of that heavy rain may travel from parts of southern and eastern Texas to portions of the Tennessee and lower Ohio valleys.
Any rain has the potential to induce flash and urban flooding, but the benefits of the rain in the central U.S. may far outweigh localized problems from flooding, rainy outdoor activities and slow travel. Since both the upcoming and ongoing rain have hit multiple parts of the Mississippi River watershed, some positive response in water levels is likely in the coming days and weeks.
The water level rise on the navigational portion of the Mississippi River main stem will depend on the amount of rain that falls in addition to the boost in water levels on major tributary rivers including the Arkansas, Missouri, Ohio and Mississippi river headwaters and timing thereof.
Between the zone of drenching rain and snow will be a shallow push of cold air that has the potential to produce a zone of sleet and freezing rain.
Early-season ice events are always tricky as much of the ground tends to remain too warm to allow much ice to accrue, explained AccuWeather Senior Meteorologist Dan Pydynowski.
“But the air coming in is plenty cold enough to allow ice to form at least on some elevated surfaces over portions of the southern and central Plains from late Saturday to Sunday morning,” Pydynowski said.
At this time, AccuWeather meteorologists have pinpointed an area from the Texas and Oklahoma panhandles to southeastern Colorado to western and central Kansas as most likely to face ice concerns. There is a chance that freezing rain extends all the way through northeastern Kansas and northwestern Missouri. Most likely the icy areas will be limited to elevated surfaces, such as bridges and overpasses, but there can be some exceptions.
Some of the cities that are likely to experience freezing rain include Amarillo, Texas, Gage, Oklahoma, and Dodge City, Kansas. There is a chance that some icy patches develop around Topeka, Kansas, Kirksville, Missouri, and part of the Kansas City, Missouri, metro area from Saturday night to Sunday morning.
Pockets of sleet and freezing rain will occur as far to the northeast as the Great Lakes region as the weekend progresses. Cold rain will likely fall on the major hubs of Chicago, St. Louis and Detroit.
“Temperatures will plunge into the 20s in the wake of the storm from Amarillo to Kansas City and Chicago by early next week,” Dombek said, adding, “At that level, the lowest readings of the season so far will be undercut by 10-20 degrees.”
Source : Yahoo News