From a blizzard and a severe storm outbreak across the nation's heartland to a tropical storm in the Gulf and unusual warmth in the East, extreme weather for October struck the U.S. late last week and into the weekend.
AccuWeather Expert Senior Meteorologist Brett Anderson attributes the wild weather to the jet stream pattern. The jet stream is a channel of high winds in the atmosphere, around the altitude where planes fly.
"The jet stream pattern across North America was highly amplified, which means the jet stream more resembled a roller coaster," Anderson said. "A highly amplified pattern can lead to stronger, slow-moving storms, while other regions in the U.S. can see persistently warm and dry weather for days on end."
More drastic weather changes are in store for much of the country this week.
Blizzard Cuts Travel From Wyoming to South Dakota
An all-out blizzard raged across portions of Wyoming and South Dakota on Friday into the weekend as a storm strengthened to the lee of the Rockies.
Winds gusting to 40-60 mph whipped heavy snow around, reducing the visibility to a quarter of a mile and near zero at times. The heavy snow forced portions of I-25 and I-90 to close, while the weight of the heavy, wet snow downed trees and powers lines and cut power to some communities.
The blizzard unleashed a total of four feet of snow near Deadwood, located in the Black Hills of South Dakota. Rapid City, S.D., was buried by 23.1 inches of snow. According to the Rapid City National Weather Service (NWS) office, that is more snow than the city has ever recorded during the entire month of October.
"It is not all that unusual to have significant snow in the Rockies and Black Hills this time of year, but it is rare to have snowfall measured in feet in early October," Anderson said.
This week, temperatures are soaring into the upper 50s and lower 60s across the same communities that were digging out from snow over the weekend. The snow will be melting, leaving a much different landscape compared to this past Saturday.
Destructive Tornadoes Strike the Midwest
One the warmer side of the storm, a severe storm and tornado outbreak unfolded. Tornadoes touched down across portions of Nebraska and Iowa late Friday.
"The strong storm that moved out of the Rockies allowed cold air from the West to clash with unusually warm and humid air from the East," Anderson said. "The combination of this and strong jet stream created a classic setup for damaging thunderstorms and tornadoes."
A violent, EF-4 tornado ransacked Wayne, Neb., on Friday evening, injuring 15 people according to the Associated Press, destroying houses, flipping vehicles, flattening hangers and tumbling private aircraft at the Wayne Municipal Airport.
All roads into Wayne are closed. DO NOT come into Wayne— City of Wayne (@CityofWayne) October 4, 2013
Much calmer weather will be in place this week as high pressure dominates. A southwesterly breeze will usher in warmer air. Highs will reach the lower to mid-70s for Omaha, Minneapolis and Chicago this week.
Tropical Storm Karen Enhances Rain
Tropical Storm Karen formed in the southern Gulf of Mexico on Thursday morning, Oct. 3, 2013. It churned northward across the Gulf into the weekend. It was downgraded to a tropical depression as it stayed out over the open waters of the northern Gulf on Saturday, Oct. 5, 2013 and then it became a tropical rainstorm on Sunday.
While it will not make landfall as a named storm, it will enhance rainfall along the central Gulf Coast to northern Florida early this week, threatening localized flooding.
Part of the remnants of Karen will emerge over the western Atlantic. Through the middle of the week, a soaking rain will dampen portions of the Southeast and mid-Atlantic coast. Locally, more than three inches of rain will deluge eastern portions of the Carolinas. Thick cloud cover and rain will keep temperatures down from the above-normal warmth to start the month. Gusty, onshore winds will make it feel even cooler.
Unusual Warmth Grips the East
So far in October, highs have been as much as 10-20 degrees above normal for portions of the Southeast and mid-Atlantic, including Raleigh, Washington, D.C., and Philadelphia.
The same cold front that triggered the tornadoes in the Midwest is bringing a round of downpours with locally damaging winds to the East early this week. The storms will cut back at the above-normal warmth, allowing temperatures to return closer to normal for this time of the year, which are in the upper 60s and the lower 70s.
Santa Ana Winds Spread Wildfires
Strong Santa Ana winds blasted Los Angeles, Ventura and Santa Barbara counties Friday through the weekend with a few gusts as high as 90 mph. The winds were strong enough to uproot trees across parts of Southern California.
Due to the strong winds and severe drought conditions gripping the region, the Los Angeles NWS office declared that there was the highest fire threat in five years.
A fire ignited at Camp Pendleton in San Diego County, west of Fallbrook, Calif., on Saturday, Oct. 5, 2013. The fire forced evacuations of the base hospital and housing over the weekend, but these evacuations have since been lifted. According to Camp Pendleton on Facebook, the fire has consumed 2,500 acres as of Monday afternoon.
A storm will take aim at the Southwest during the middle of this week, bringing rain to Southern California. While the rain will be beneficial for the drought-stricken area, the rain will cause oil residue to surface on roadways, leading to slippery and treacherous travel, especially at intersections and when traveling at highway speeds.
The rain may also result in flooding, especially in recent burn scar areas.