A major winter storm is forecast for the central portions of the United States on Monday, bringing more than a foot of snow locally. The worst conditions will develop from northern Kansas through Iowa. A wintry mix with freezing rain potential is possible to the south of the narrow deep snowpack. Further south, severe thunderstorms are possible across Oklahoma and Texas.
While parts of the Midwest are already experiencing some winter weather this weekend, a much more intense winter storm is coming up on Monday through Tuesday for parts of the Plains and the Midwest.
A progressive weather pattern is now developing over the United States with a large upper wave over the West Coast. The wave is bringing a much colder air mass far south into the western portions of the country, with quite a significant rain event for the region, including parts of California and the desert Southwest.
Off the West Coast trough, a wave ejects towards the east across the Rockies and crosses the central United States. It will lead to a dangerous winter storm on Monday through Tuesday, developing across the Great Plains and Midwest with very heavy snowfall and also some ice accumulation along the wintry front.
The National Weather Service (NWS) has numerous winter storm warnings and advisories ahead of the developing system, strengthening on Monday. The system will continue east towards the Ohio Valley and the Mid-Atlantic Coast on Tuesday.
There is also severe weather potential with an enhanced threat of large hail and damaging winds across parts of the southern Plains. A Slight Risk of severe thunderstorms over parts of the Southern Plains on Sunday into Monday morning. Showers and thunderstorms will advance into parts of the Ohio/Tennessee Valleys on Monday.
Along the frontal line, rain/freezing rain areas will develop across the Central Plains, Middle Mississippi Valley through Sunday evening. There will be freezing rain along its track, as well as locally quite a deep snowpack to the north, across northern Kansas, southeast Nebraska, and southern Iowa.
By Monday evening, rain moves into parts of the Southeast and southern Mid-Atlantic.
The more significant weather change has started a few weeks ago, which is coming into effect this late January. Let’s see what happened actually.
POLAR VORTEX COLLAPSE BROUGHT A PATTERN CHANGE
Through the final days of 2020, there was a world record for the highest surface pressure ever observed, set in Mongolia. It was caused by very cold air with below -50 °F sitting over Russian Siberia.
The Siberian frigid cold air mass then spread towards the Pacific, ramping up the jet stream and lead to another record-setting setup for the North Pacific and Alaska. An extremely deep extratropical low occurred which pushed the minimum central pressure to new record levels for the region, 921 mbar!
You might be asking now, but why is this important here?
These large mesoscale systems were so anomalous, that their dynamics sent the atmospheric waves up into the upper parts of our atmosphere – the stratosphere.
The result was a disruption of the Polar Vortex aloft and a major Sudden Stratospheric Warming (SSW) event occurred. The Polar Vortex then collapsed.
The warming was so intense that the cold was then displaced and pushed to the south, away from the polar regions. After the Polar Vortex collapse in early January, the weather patterns across the Northern Hemisphere are becoming very dynamic and progressive over the past few weeks. As it often happens, a strong blocking ridge develops over the polar/arctic region with a strong high-pressure system built over Greenland.
Across the west parts of the North American continent, a deep wave can be seen on the chart above, spreading a significant cold outbreak into the western portions of the United States, starting this weekend. It will extend through the remainder of this month. The attached chart hints at an extreme cold to develop across western Canada and northern/northwestern United States first, then spread towards the West Coast.
With the general pattern sending the upper wave and cold air mass that far south, it also cuts off a potent wave towards the central United States tonight. This wave is now becoming the main focus for the weather in the coming days, as a major winter storm will develop across the central parts of the country towards the Midwest on Monday through Tuesday this coming week.
The system could even challenge the existing snow records from the past 30 years over the area, as weather models are hinting at some potential for near 15 inches (40 cm) of total snowfall by Tuesday morning across Nebraska. Omaha for example has the all-time record set at 18.5 inches (1965), while lately, 14.1 inches was recorded in January 2005. Some other cities might get close to these records as well.
Millions will be in the zone of wintry mix precipitation coming up over the next 48 hours and can expect travel disruptions and also power outages caused by severe weather hazards. Freezing rain and ice potential could also occur.
The freezing rain forms when a layer of warm air aloft is placed above a layer of below-freezing (subfreezing) air at the surface. Snowflakes that falling towards the ground, melt as they fall through this warm layer.
If the snowflakes are completely melted, then it is falling as rain towards the ground which is much colder. This liquid droplet then freezes on contact with exposed surfaces.
Sleet or ice pellets are a form of precipitation consisting of small, translucent balls of ice. Ice pellets are smaller than hailstones and are different from graupel. Ice pellets often bounce when they hit the ground or other solid objects (e.g. jackets, windshields, and dried leaves). They generally do not freeze into a solid mass unless mixed with freezing rain.
WINTRY MIX DEVELOPS OVER THE CENTRAL PLAINS
As the new wave emerges across the southern Rockies through tonight (Sunday night), the lee surface low forms over the Plains. The result will be a strong warm advection northwards. Setting a stage for a potentially significant winter storm across the central Plains and the Midwest tomorrow, on Monday.
Thanks to the deepening surface low, cold advection spreads behind the front as upper High is established over southern Canada. Meaning the surface flow is meridional, northerly into the United States from the north. This creates a high contrast in temperatures across the country.
With the deepening low, precipitation begins to increase through Sunday night. Snowfall begins from eastern Colorado into western and northern Kansas, to the north of the warm frontal boundary extending from the Panhandsles to northern Missouri on Monday early morning.
With still below-freezing temperatures near the surface and much warmer air mass coming north aloft, conditions could support freezing rain potential across central Kansas towards northern Missouri.
Although the potential for freezing rain is rather limited, it may lead to dangerous travel conditions due to black ice on the roads. As the system heads further northeast through late Monday morning, precipitation should become heavy snowfall, mixing from the west.
Forecast message from the Dodge City, Kansas NWS Office
Accumulating snowfall appearing more and more likely for southwest and north-central Kansas Sunday night through Monday. Although exact accumulations still remain unclear, the best chance of 2 to 4 inches of snowfall will be north and northeast of Dodge City. There is a chance for a wintry mix south of Dodge City and around the Pratt and Medicine Lodge areas Sunday night which will result in lower snowfall totals but it could also produce some minor ice accumulations.
Snow totals of 2 to 4 inches are possible with minor ice accumulations not out of the question southeast of Dodge City Sunday night. Currently appears that the highest snowfall totals will be north and east of Dodge City developing early Sunday night with the steadier and heavier snowfall being possible from midnight to noon Monday. Activity will taper off Monday afternoon.
Further south along the cold front, warm air mass becomes unstable across Texas and parts of Oklahoma. Settings an environment conducive for thunderstorms to develop, including severe storms. See further down for details on this matter.
WINTER STORM INTENSIFIES ON MONDAY
Through late morning Monday, the surface low peaks its intensity so the precipitation increase further. This will start very heavy snowfall across central Kansas, thanks to the advection of colder air mass in the system’s wake while moist air is still pumping north with the low over Oklahoma.
Freezing rain potential will spread across northeast Kansas, northern Missouri into central Illinois and Indiana. To the north of this frontal line, heavy snowfall will begin.
Further south, heavy rain and thunders move east into Missouri and Arkansas, with some potential for severe weather threat remaining along the front extending down towards eastern Texas. The advection of very warm air mass will continue across Lower into the central Mississippi Valley, with also high dewpoints that will lead to heavy rain along the front.
The advection of colder air mass from the Northern Plains will spread south across Nebraska into western Kansas and Colorado. Being the most intense over Minnesota and North Dakota, with Highs in the 5-10 °F range.
Forecast message from the Hastings, Nebraska NWS Office
Winter Storm Warning is in effect from midnight tonight to 3 AM Tuesday as heavy snowfall is expected for portions of north-central Kansas and east-central and south-central Nebraska. Possibly preceded by a brief period of freezing drizzle. Total accumulations of generally 6 to 11 inches, with the highest amounts, focused south and east of the Nebraska Tri-Cities. Ice accumulations of a light glaze.
Northerly winds during the majority of falling snow will average 10 to 20 mph with gusts up to around 30 mph, so at least some minor drifting is likely.
Any light icing from freezing drizzle should mainly occur before sunrise Monday, as precipitation first gets underway. The majority of heaviest snowfall intensity will then occur during the daytime hours Monday before decreasing in intensity Monday evening into the overnight hours.
Below is the forecast message from the Topeka, Kansas NWS Office which areas will see worsening conditions from late Monday morning onwards.
A rather potent winter storm is still on track to move into the area late Sunday and last through most of the day on Monday. Precipitation is expected to increase across the area Monday morning, beginning as light freezing rain or sleet, and then transitioning to snow.
There will be a very tight gradient between the highest snowfall amounts across far northern Missouri and very little snow, more toward the Highway 36 corridor and areas south.
Winter storm warning is in effect from 3 am to 6 pm Monday as heavy snowfall, possibly mixed with freezing drizzle is expected across portions of north-central and northeast Kansas. Total snow accumulations of 6 to 9 inches and ice accumulations of a light glaze.
A freezing drizzle may occur very early Monday morning before transitioning to all snow before sunrise. The heaviest snowfall is expected to occur during the daytime hours on Monday, tapering off Monday evening.
Travel could be very difficult and treacherous. The hazardous conditions could impact the morning and evening commutes. If you must travel, keep an extra flashlight, food, and water in your vehicle in case of an emergency. Some slick roads are possible, especially on elevated surfaces and untreated roads.
SNOW CONTINUES INTO MIDWEST THROUGH MONDAY EVE
With time, the increasing precipitation also spread into the southern parts of the Midwest United States. Very heavy snowfall with significant accumulations is likely from northern portions of Kansas, southern Nebraska into southern Iowa and western Illinois. Near 10-12 inches of snow is quite possible to accumulate in this narrow zone as conditions will be favorable for high snowfall rates for a long time while the winter storm slowly drifts east.
Freezing rain potential will remain further east towards the Ohio Valley on Monday evening into the night. Most likely from central Illinois into central Indiana and central Ohio.
Further south, the cold front will continue advancing east across the Lower Mississippi Valley and towards the Southeast United States through Monday night. Some potential for severe weather will remain across Mississippi, Alabama, and Tennessee.
Below is a Forecast message from the Omaha, Nebraska NWS Office regarding the potential in the area of both Nebraska and Iowa through Monday evening hours:
A powerful winter storm system with high impacts will bring snow accumulations of 4-12 inches along and south of interstate I-80 on Monday. Wind gusts up to 25 mph will help reduce visibility as roads become slick and difficult to travel. Expect heaviest snowfall rates between noon and 6 pm, impacting the evening commute.
Winter Storm Warning is in effect from 3 AM Monday until 3 AM Tuesday. Accumulations 6 to 12 inches are expected within the Winter Storm Warning and inches of snow are expected north of the Winter Storm Warning area.
Southeast Nebraska and southwest Iowa should see the highest snowfall amounts. This snow is expected to be of the wet and heavy variety and will require increased effort to remove.
Forecast message from the Dew Moines, Iowa NWS Office
Major Winter Storm will impact Iowa Monday and Monday night. Very heavy snowfall is expected mainly south of Interstate 80. Moderate intensity to the north but a sharp gradient is likely. Blowing and drifting snow is likely as well. Travel Monday afternoon and evening will likely be extremely difficult.
Winter Storm Warning issued for Monday and Monday Night central and south. Winter Storm Watch has been issued in Highway 30 and Highway 20 corridor areas. A sharp gradient is likely somewhere between Interstate 80 and Highway 20. Snowfall amounts in this area are less certain.
Significant travel impacts Monday and Monday night over portions of central and southern Iowa. Travel may become nearly impossible at times Monday afternoon and even as peak snow rates and peak northeast winds gusting to over 30 mph at times. Low visibilities and drifting of snow will make unplowed roads very difficult to navigate.
Travel will be difficult on unplowed roads in the heavy snowfall areas, even not taking into account low visibilities. The Monday evening commute will be greatly impacted. Travel may need to be postponed or rescheduled.
Forecast message from the Chicago, Illinois NWS Office
The potential for significant snow accumulations continues to increase. Questions still remain, however, regarding the placement of a swath of higher totals, as well as how far north any mixing with freezing rain/sleet and freezing drizzle develops Monday afternoon and evening. A sharp cutoff in snow totals on both the north and south sides appears likely.
Increasing confidence in a swath of significant 6+ inches snowfall across parts of northern Illinois Monday afternoon through Tuesday morning. Gusty northeast winds and wetter type snow may cause sporadic power outages. Potential for icing mainly south of I-80. Amounts are still somewhat uncertain. Lakeshore flooding will be possible.
Winter storm warning is in effect for portions of north-central and northeast Illinois from 1 PM Monday to 12 PM Tuesday as heavy snowfall is forecast, especially through Monday evening. Total accumulations of 5 to 8 inches with isolated higher amounts are possible. Northeast winds gusting as high as 35 mph resulting in periods of very low visibility.
Travel could be very difficult. Hazardous conditions are likely to impact the Monday evening and Tuesday morning commutes. Some power outages are possible due to the combined effects of the expected wetter nature of the snow and strong and gusty winds. Freezing rain and freezing drizzle, or sleet, may mix in with the snow at times, mainly later Monday night for locations south of I-88.
FREEZING RAIN AND SNOW SPREAD EAST ON TUESDAY
The freezing rain potential will develop in a rather narrow zone throughout Monday. Basically very near the warn frontal zone moving east-northeast during the day. Although the ice accumulations are unlikely to be significant, travels could be disrupted. The latest model guidance suggests the highest potential is from northeast Kansas across northern Missouri, central Illinois to northern Indiana and Ohio.
To the north of this line, very heavy snowfall should result in the high accumulation with this winter storm. Potential is the highest across northern Kansas, south-southeast Nebraska and southern Iowa. These areas could receive near 8 to 12 inches of snow by Tuesday morning, potentially even more – close to 15 inches – if heavy snow bands develop and persist for a longer period of time.
Nevertheless, an increasing potential is definitely in a place that the wintry conditions will develop along with the frontal system.
THREAT FOR SEVERE WEATHER ACROSS THE SOUTHERN PLAINS
Further south of the core with ongoing winter weather mix, a strong warm advection will be underway, associated with the surface low traveling across the southern Great Plains. The surface low typically forms in the lee side of the Rockies with an upper wave/through emerging from the west. The process deepens the low.
With the pressure falls over the southern Plains, rather strong southerly winds will be advecting moist and warm air mass from the warmer Gulf of Mexico further north across the Plains and the Mississippi Valley. Leading to an unstable environment ahead of the moving frontal system.
This will push dewpoint temperatures into low to mid-60s °F far north, past the Red River and central Arkansas. Unstable air mass under the left-exit region of an upper-level jet stream will introduce another region for dangerous severe weather threat through late Sunday night into Monday morning.
According to the SPC, a few severe storms capable of producing large hail, isolated damaging wind gusts, and perhaps even a brief tornado may occur over portions of North Texas, southern and eastern Oklahoma from Sunday evening through Monday morning. An SLGT (slight) risk has been issued.
Southern Plains into the Ozark Plateau
The recent surface analysis places a frontal low near SPS, with the cold front extending northeastward to another low in northeast OK and southwestward into the Permian Basin. A shortwave trough remains well west of the region over the Lower CO River, keeping warm-air advection as the primary forcing for the ascent. A few storm clusters have developed within this regime with several deeper updrafts noted over northwest TX and central TX.
With the cold front forecast to continue gradually southeastward, any afternoon/evening storms will occur north of the front. The expectation is for overall coverage to increase this evening across OK and AR as the low-level jet increases. As mentioned in the previous outlook, a combination of modestly elevated buoyancy and strong vertical shear will result in the potential for hail through the evening.
As the shortwave trough and its attendant forcing move closer tonight, storm coverage will likely increase from west TX across OK and into northern AR. Hail will remain the primary threat with these storms. A relatively small corridor of surface-based storms may develop along and just ahead of the front from far south-central OK into north-central TX early Monday morning, continuing east just ahead of the front thereafter.
The overview graphics by the National Weather Service in Norman, Oklahoma above hint a few severe storms with hail up to the size of quarters, winds up to 60 mph and very low tornado potential is possible late Sunday into early Monday morning.
DROUGHT RELIEF FOR THE DESERT SOUTHWEST
This new winter storm, ejecting of the significant trough into the western Contiguous United States, will introduce dangerous travel conditions as severe winter weather is forecast. There are likely high snowfall accumulations across portions of the North-Central Plains and the Midwest, with locally close to 15 inches of snow by Tuesday.
To the immediate south of this broad swath of heavy snow, freezing rain potential could bring some minor ice accumulations. And a lot of rain is expected to accumulate with the system over the next 5-7 days, gradually spreading towards the East Coast of the United States this week.
The channel established from western Canada opens the flow of much colder weather than normal towards the south, actually pretty far south across the West Coast, Baja California peninsula, and the desert Southwest US. Temperatures could drop much lower than normal, even near 15 degrees below average in some areas.
And probably the most important effect of the event for the West is the relief for the severe drought conditions ongoing from California into the Southwest United States, so this rain is much appreciated there. Indeed as heavy snow over the Sierra Nevada and further east-northeast into the Rockies.
See the previous discussion: