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Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.Fire and Ice on the Plains: Intense Snow, Raging Blazes
A tightly wrapped storm system produced a wild array of weather-related impacts over the Great Plains and Midwest on Wednesday, including paralyzing snowfall, severe thunderstorms, and a massive prairie fire. The most widespread problems occurred with late-season snowfall that stretched along a frontal zone from the Colorado Rockies northeast more than 1,000 miles to Michigan. Dubbed Winter Storm Selene by the Weather Channel, the heavy snow and high winds knocked out power to thousands of residents. Snow totals of a foot or more were reported in Iowa, Minnesota, South Dakota, Wisconsin, and Wyoming, according to TWC, with 31.6” falling near the mountain town of Pinecliff, CO.
Figure 1. A lone pedestrian trudges along the westbound lanes of Speer Boulevard in downtown Denver as a spring storm packing high winds and wet, heavy snow blankets the city early Wednesday, March 23, 2016. Image credit: AP Photo/David Zalubowski.
Figure 2. An unidentified exotic creature took shape on the railing of my deck at the height of the snowstorm on Wednesday, March 23, 2016. Image credit: Bob Henson.
Snowstruck: A first-hand report
One of the hardest-hit areas was my own neck of the woods, the Denver-Boulder area. As late as Monday night, most computer forecast models had been distinctly lukewarm about the chance of major snow in the populous Front Range corridor, adjoining the Rockies. The classic scenario for big snow here is for an upper-level storm to move slowly from the Four Corners region across southern Colorado, forcing strong, deep upslope flow against the Front Range mountains. Models were on target in projecting that Wednesday’s storm would crank up just east of the Front Range, a setup that often produces blizzard conditions east of the Denver area. As it happened, the storm intensified just close enough to the Front Range to push blizzard conditions into much of the urban corridor, along with extremely heavy snowfall rates that peaked as high as 4”/hour. High-resolution short-range models fell into agreement on this trend Tuesday evening, just a few hours before the storm hit full force.
Roads and yards were still wet at my place in Louisville (just east of Boulder) when the snow began around 2 AM Wednesday. By 9 AM, there was almost a foot of snow on the ground. By the time the storm was wrapping up, around 1 PM, I measured a phenomenal 21” accumulation—all of it having fallen in just 10 hours! Similar readings between 20” and 25” were observed in a swath from just east of Boulder across the north and east Denver suburbs, as well as in many of the often-hard-hit foothills locations to our west. Interstates were closed throughout the region for hours, as was Denver International Airport.
El Niño gives big snow a boost in northeast Colorado
The odds of a big winter storm go up considerably in the Boulder area during El Niño events. An informal study by Boulder cooperative observer Matt Kelsch (University Corporation for Atmospheric Research) found that, since 1950, nearly half of the Boulder snowstorms measuring at least 15” occurred during El Niño. Less than 20% happened during La Niña.
Figure 3. A old train trestle bridge burns near Lake City, KS, on Wednesday, March 23, 2016. The bridge was set afire by a large grass fire burning in Barber County, KS. Lake City is about 15 miles northwest of Medicine Lodge, where at least two homes were destroyed by fire. Image credit: Travis Morisse/The Hutchinson News via AP.
Figure 4. The hourly Air Quality Index briefly reached the “unhealthy for sensitive groups” level (orange) across part of south-central Kansas at 8:00 pm CDT Wednesday, March 23, 2016, as particulate matter from a massive grass fire blew into the area. Image credit: AirNow.gov, data courtesy of Kansas Department of Health and Environment.
Fierce fire spreads from Oklahoma to Kansas
To the south of the big snow, warm, bone-dry air and powerful southwest winds gusting above 60 mph kicked off a number of grass fires, including one gargantuan fire that crossed the Oklahoma-Kansas border. In less than 48 hours, this fire tore across a swath estimated by the Oklahoma Forestry Service as spanning an immense 400,000 acres (625 square miles). The fire sent a pall of smoke over much of southern Kansas, including the Wichita area (see Figure 4). At least two homes were destroyed in Medicine Lodge, KS, and the town of 2000 residents was under a voluntary evacuation. With the fire still out of control late Wednesday, Kansas governor Sam Brownback declared a state of disaster. Hundreds of firefighters were reportedly working on Thursday morning along a 30- to 40-mile-long fire line. The fire’s cause is under investigation. NOAA’s Storm Prediction Center (SPC) had warned of extreme fire risk from southeast New Mexico to eastern Kansas on Wednesday. A WU station at Medicine Lodge reported wind gusts of 51 mph on Wednesday afternoon as the relative humidity dipped below 10%.
Figure 5. VIIRS view of the state of Kansas (outlined) at 1946Z (2:46 pm CDT) on Wednesday, March 23, 2016. Thick cloudiness in northwest Kansas is associated with heavy snow, while the streaks of smoke at center are being produced by major grass fires near the KS/OK border. Image credit: USDA Forest Service/Remote Sensing Applications Center.
Figure 6. A MODIS view of the western two-thirds of Kansas at 1948Z (2:48 pm CDT) on Wednesday, March 23, 2016. False color is used to highlight areas of cold cloud tops (top left) and wildfire (bottom center). Image credit: USDA Forest Service/Remote Sensing Applications Center.
Severe weather possible across South on Thursday
A line of severe thunderstorms erupted Wednesday evening ahead of a dry line, with some of the most intense storms extending roughly from Tulsa, OK, to Dallas-Fort Worth, TX. No tornadoes were reported, and there were only a few reports of thunderstorm-related high wind, but large hail up to golf-ball size was widespread. (Update: Storm surveys on Thursday confirmed three tornadoes from Wednesday, one each in Arkansas, Texas, and Missouri.) Another round of severe storms is possible on Thursday from central Kentucky and Tennessee into parts of Mississippi, Alabama, and Georgia, where NOAA/SPC outlined a slight risk of severe weather in its initial Day 1 outlook for Thursday. Wind damage is a particular concern with any squall lines or line segments that emerge. Instability could be somewhat higher across the mid-South late this weekend as another upper-level storm approaches the region. SPC’s long-range convective outlook is calling for a potential risk of severe weather on Sunday, centered on western Kentucky and Tennessee.
We’ll be back with our next post on Friday.
Bob Henson
Figure 1. A lone pedestrian trudges along the westbound lanes of Speer Boulevard in downtown Denver as a spring storm packing high winds and wet, heavy snow blankets the city early Wednesday, March 23, 2016. Image credit: AP Photo/David Zalubowski.
Figure 2. An unidentified exotic creature took shape on the railing of my deck at the height of the snowstorm on Wednesday, March 23, 2016. Image credit: Bob Henson.
Snowstruck: A first-hand report
One of the hardest-hit areas was my own neck of the woods, the Denver-Boulder area. As late as Monday night, most computer forecast models had been distinctly lukewarm about the chance of major snow in the populous Front Range corridor, adjoining the Rockies. The classic scenario for big snow here is for an upper-level storm to move slowly from the Four Corners region across southern Colorado, forcing strong, deep upslope flow against the Front Range mountains. Models were on target in projecting that Wednesday’s storm would crank up just east of the Front Range, a setup that often produces blizzard conditions east of the Denver area. As it happened, the storm intensified just close enough to the Front Range to push blizzard conditions into much of the urban corridor, along with extremely heavy snowfall rates that peaked as high as 4”/hour. High-resolution short-range models fell into agreement on this trend Tuesday evening, just a few hours before the storm hit full force.
Roads and yards were still wet at my place in Louisville (just east of Boulder) when the snow began around 2 AM Wednesday. By 9 AM, there was almost a foot of snow on the ground. By the time the storm was wrapping up, around 1 PM, I measured a phenomenal 21” accumulation—all of it having fallen in just 10 hours! Similar readings between 20” and 25” were observed in a swath from just east of Boulder across the north and east Denver suburbs, as well as in many of the often-hard-hit foothills locations to our west. Interstates were closed throughout the region for hours, as was Denver International Airport.
El Niño gives big snow a boost in northeast Colorado
The odds of a big winter storm go up considerably in the Boulder area during El Niño events. An informal study by Boulder cooperative observer Matt Kelsch (University Corporation for Atmospheric Research) found that, since 1950, nearly half of the Boulder snowstorms measuring at least 15” occurred during El Niño. Less than 20% happened during La Niña.
Figure 3. A old train trestle bridge burns near Lake City, KS, on Wednesday, March 23, 2016. The bridge was set afire by a large grass fire burning in Barber County, KS. Lake City is about 15 miles northwest of Medicine Lodge, where at least two homes were destroyed by fire. Image credit: Travis Morisse/The Hutchinson News via AP.
Figure 4. The hourly Air Quality Index briefly reached the “unhealthy for sensitive groups” level (orange) across part of south-central Kansas at 8:00 pm CDT Wednesday, March 23, 2016, as particulate matter from a massive grass fire blew into the area. Image credit: AirNow.gov, data courtesy of Kansas Department of Health and Environment.
Fierce fire spreads from Oklahoma to Kansas
To the south of the big snow, warm, bone-dry air and powerful southwest winds gusting above 60 mph kicked off a number of grass fires, including one gargantuan fire that crossed the Oklahoma-Kansas border. In less than 48 hours, this fire tore across a swath estimated by the Oklahoma Forestry Service as spanning an immense 400,000 acres (625 square miles). The fire sent a pall of smoke over much of southern Kansas, including the Wichita area (see Figure 4). At least two homes were destroyed in Medicine Lodge, KS, and the town of 2000 residents was under a voluntary evacuation. With the fire still out of control late Wednesday, Kansas governor Sam Brownback declared a state of disaster. Hundreds of firefighters were reportedly working on Thursday morning along a 30- to 40-mile-long fire line. The fire’s cause is under investigation. NOAA’s Storm Prediction Center (SPC) had warned of extreme fire risk from southeast New Mexico to eastern Kansas on Wednesday. A WU station at Medicine Lodge reported wind gusts of 51 mph on Wednesday afternoon as the relative humidity dipped below 10%.
Figure 5. VIIRS view of the state of Kansas (outlined) at 1946Z (2:46 pm CDT) on Wednesday, March 23, 2016. Thick cloudiness in northwest Kansas is associated with heavy snow, while the streaks of smoke at center are being produced by major grass fires near the KS/OK border. Image credit: USDA Forest Service/Remote Sensing Applications Center.
Figure 6. A MODIS view of the western two-thirds of Kansas at 1948Z (2:48 pm CDT) on Wednesday, March 23, 2016. False color is used to highlight areas of cold cloud tops (top left) and wildfire (bottom center). Image credit: USDA Forest Service/Remote Sensing Applications Center.
Severe weather possible across South on Thursday
A line of severe thunderstorms erupted Wednesday evening ahead of a dry line, with some of the most intense storms extending roughly from Tulsa, OK, to Dallas-Fort Worth, TX. No tornadoes were reported, and there were only a few reports of thunderstorm-related high wind, but large hail up to golf-ball size was widespread. (Update: Storm surveys on Thursday confirmed three tornadoes from Wednesday, one each in Arkansas, Texas, and Missouri.) Another round of severe storms is possible on Thursday from central Kentucky and Tennessee into parts of Mississippi, Alabama, and Georgia, where NOAA/SPC outlined a slight risk of severe weather in its initial Day 1 outlook for Thursday. Wind damage is a particular concern with any squall lines or line segments that emerge. Instability could be somewhat higher across the mid-South late this weekend as another upper-level storm approaches the region. SPC’s long-range convective outlook is calling for a potential risk of severe weather on Sunday, centered on western Kentucky and Tennessee.
We’ll be back with our next post on Friday.
Bob Henson
@KAKEnews smoke plume over Wichita. pic.twitter.com/OUGTtHPhgL
— Jenny Paulson (@jennithecat) March 23, 2016
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Smoke covered sun
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