If you want to know what to know what an “extreme weather day” is…look to today.

Today/tomorrow’s mid-latitude cyclone on the Great Plains and Midwest will be a powerful one and one which will provide something for everyone. Blizzards, wind, severe storms, flash flooding, fire…pick your poison, Nature will provide.

In places like Minneapolis and much of Nebraska, this storm threatens to be a historic late-season April heavy snow or blizzard event. In the southern Midwest and South, it threatens heavy rain, flooding and a tornado outbreak. On the southern Plains, strong winds and arid conditions, could further yesterday’s extreme fire behavior. Stay safe out there folks!

A reminder, I will be interviewed on the internet-based program Environmental Coffeehouse at 9 pm EDT/6 pm PDT tonight! A livestream will be available on their public FB page (so you should be able to see it regardless of whether you have a FB page or not). I will discuss abrupt climate change and increasing extreme weather events and how current events (ocean heatwaves, changing jet stream, etc) connect to our rapidly changing climate.

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The beast of an extratropical cyclone over the Great Plains today.
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Progression of the Great Plains/Midwest Cyclone Friday-Saturday.
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Probability of at least 4 inches of snow during the 24 hr period.

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Moderate Risk of severe thunderstorms (Level 4 out of 5) over Central and Southwest Arkansas and extreme northwest Louisiana and small portion of East Texas. Multiple tornadoes possible in the region, with isolated strong tornadoes. Damaging winds and very large hail also possible across a larger region from Iowa southward.

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Moderate Risk (Level 4 out of 5) of Flash Flooding across much of central and southern Arkansas into far northern Louisiana based on possible 1 to 3 inch rainfall rates.

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Extremely Critical Fire Risk (3 out of 3) from southern and Southwest New Mexico into West and North Texas and and western Oklahoma. Conditions exist for extreme fire behavior. Threat is being enhanced by winds associated with today’s cyclone.
If you’re wondering why all this is happening…VERY amplified…or in other words…very wavy jet stream pattern bringing extremely cold air (by April standards) down from from Canada to meet with up with extreme warm air (again by April standards) up from the south. Temps in 20s and 30s to the north with a high of 101 in Western Oklahoma yesterday to the south. Right now Lincoln, NE (where I am) is hitting 80 degrees for the first time this year. Tomorrow, Lincoln will peak in the mid-30s with falling temperatures!

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Massive long wave trough moving over the High Plains from the intermountain West of the US. The trough dips as far south as extreme northern Mexico.
The front end of this trough caused the development of the surface cyclone over Nebraska, intensifying deep moisture movement from the Gulf of Mexico (which, by the way, as a moisture source region, is running well above normal to start the year) and as and providing the deep vertical wind shear (rapidly increasing wind speeds with height) need to generate sustained severe thunderstorms. A recipe for a multi-threat mid-latitude frontal system. And it will not stop anytime soon. Saturday night, the threat will spread eastward, where a significant ice storm event may be possible for portions of upstate New York. In fact, Saturday afternoon, there may be much of Pennsylvania in the 70s while much of Upstate New York may be in the 20s! Incredible temperature contrasts for such a relatively higher latitude location.

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One model depiction (North American Model) show significant temperature contrasts over relatively short distances along a warm front near the PA-NY border Saturday Afternoon. NAM is a colder solution and there are disagreements on where freezing rain line may end up, but any major freezing rain this late in the season in Upstate New York will be quite unusual.

—Meteorologist Nick Humphrey

 

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Stay safe out there today! Severe storms likely and in progress.

Nebraska is in the ice box still…but big storms, including tornadoes and significant straight line wind damage possible in parts of Indiana and Kentucky today.

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Warm, moist air, and lots of vertical wind shear. Good set up for some nasty severe weather.

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Prominent severe weather threat is between the polar and subtropical jets (northerly and southerly branches, respectively). In between, lots of mass is being removed allowing for storms to explode from below, intensify rapidly and maintain themselves in the highly sheared environment (winds rapidly increasingly with height).

There is a lot of speed shear, but not as much change in direction with height, which favors lines of storms. So the threat for damaging winds is quite significant, hence the “moderate risk” (4 out of 5 on the overall scale by the Storm Prediction Center) for a 45% chance of damaging wind reports within 25 miles of a point within the given region, and a 10% or higher chance of winds over 74 mph (hurricane-force). However, a significant tornado risk also exists for storms which do isolated themselves earlier this afternoon. So remain vigilant if you are in these areas and tell anyone you know to remain ready to take cover this afternoon and evening!

My part of Nebraska?

Unseasonably cold. Just straight up…cold. Starting off spring as if it were February with temperatures 25-30 degrees F below normal for highs and 15-20 degrees below normal for lows. Will have some recovery later this week, but near normal conditions (+-5 degrees F) don’t appear consistently likely until early next week. Thursday may give us a one day break with mid-50s (normal is around 60 F). So far our warmest day this year was March 3rd (73 F). The Great Plains have been part of the very wild weather pattern impacting much of the mid to upper mid-latitudes this year thanks to a highly oscillating jet stream with periods of very cold and very warm conditions relative to local norms. Much of Europe has gone through the same with very cold Arctic air mass spells, while the parts of the East Coast had record heat in February, followed by multiple cold and heavy snow periods from damaging nor’easters. All while the Arctic roasted in heat waves in this winter (relative to their norms) has significant heat and moisture moved northward, hitting sea ice hard. Here in my locality, we’ve had the roller-coaster ride of going from a a high of 4 to a high of 56 in ten days (January), a high of 22 to a high of 65 in seven days (February; and actually the high was 58 two days before that high of 22…ha!) to our mid-May days in early March (low-70s). Now after the last 5 days of March in the more seasonable 50s to low-60s, we’re spending the first three days of April barely above freezing. Winter was wild and Spring is starting off confusing weather even by spring standards. At least it’s not record breaking cold, it is unusually cold regardless though. Looking forward to the actual warmth of spring again.

High Amplitude Jet Stream Pattern To Lead to Extremely Abnormal Temps for Central/Eastern US; “Blow Torch” Heat to Arctic.

The US will be a land of extremes as a high amplitude jet stream…the story of this winter continues to impact the US as very abnormally cold temperatures impact the Central US and (later) the Great Lakes region, with very abnormal heat spreading northward into the Eastern third of the country mid-week. Sunday, much of the Great Plains were experiencing temperatures 20-25 degrees F above normal (~10-12 degrees C). As the week progresses, the jet stream amplitude over North America will intensify and bring highs of 30 degrees F (15+ C) or greater above normal mid-week to the Ohio and Tennessee Valleys into the mid-Atlantic and New England states. This means mid-Spring highs on the East Coast and a resumption of well below freezing temps over the Central and Northern Plains.

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In addition to the abnormal temperatures, another major story will be potentially heavy rainfall across a wide swath of the Midwest and Deep South ahead of the accompanying cold front which will push eastward mid-week. Abundant moisture from the Gulf of Mexico will aid in the generation of rainfall, some of which will help short term drought conditions, but could also produce flash flooding.

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Moderate risk of flash flooding over portion of Texas, Oklahoma, much of Arkansas and southern Missouri Tuesday.
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Tuesday evening forecast surface map showing widespread moderate to heavy rainfall likely from Texas to Michigan.

The Arctic Ocean has been experiencing an extraordinarily warm winter with consistent high heat to the region (relative to regional norms). As a result, sea ice has been suffering severely as the combination of high amplitude high pressure ridging and ocean cyclones push heat, wave action and wind into the sea ice sheet, along with very abnormal sea surface temperature right up against the sea ice (9-18 degrees F/5-10 degrees C above normal). Sea ice extent is currently running at the lowest on record in the history of human civilization, rapid melting already in progress in the northern Bering Sea, and 2017 annual sea ice volume was the lowest on record. The current max extent this season occurred on February 6th. The current earliest maximum peak extent is February 25th in 2015. The current record year for record minimum peak extent is 2017…2018 is currently beating that record and has the 2nd lowest year-to-date volume as well.

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The sea ice is showing some signs of refreezing after its early February peak. However, more extreme heat is to come as more storms from both the Bering Sea and the North Atlantic advance heat and moisture into the Arctic Ocean this week. One storm will move over far Eastern Siberia and into the Chukchi Sea on Tuesday. Wednesday, another, stronger storm will approach Greenland, moving over the Canadian Archipelago Thursday, slowly shifting toward the Beaufort Sea Friday.

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Note the last two sea level pressure images for 2/23 and 2/24. Not only the strength of the cyclone (in blue) but the tightly packed lines of equal pressure (isobars) between the low pressure system and the strong high pressure system over the Barents Sea, north of Scandinavia. These tightly packed isobars represent a very strong pressure gradient which will result in very strong southerly wind gusts (near hurricane-force) and intense wave action striking the sea ice sheet of the Arctic Ocean mid to late week. This in combination with the very warm, moist air moving into the region will make for a “blow torch” of heat from the Atlantic, eroding the cold conditions of the Arctic, stunting the freeze season further. This will likely lead to further ceasing or recession of sea ice as well.

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GFS forecast high temperature for Thursday, showing above freezing temperatures penetrating into the deep Arctic. This may continue into Friday. Today through Tuesday will feature near or above freezing temperatures moving out of the Bering Sea into the southern Chukchi Sea as well.

I’ve been tracking the Arctic all season and there has been a shocking level of persistent warmth in the region with 2-3 degrees C above normal temps (for the region) being quite common many more extreme day higher than that. The Arctic Ocean basin may experience, as a region, anomalous temperatures of an incredible 6-8 degrees C above normal Tuesday-Saturday. This is relative to the 1981-2010 average. However, as climate change is abruptly warming the Arctic region, leading to rapid sea ice loss compared to the past, relative to the late 19th and mid 18th centuries (in the early era of human generated climate change), the anomalies are likely 0.7 or 1  degree C higher than that, respectively.

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GFS Anomalous temperature forecasts for the Arctic region valid 00 UTC Feb 23rd. Extreme heat by regional standards over the Arctic for much of the week.

The implications for the collapse of sea ice are quite serious. The sea ice sheet regulates the jet stream by making the Arctic region permanently cold across a wide area. As long it it remains permanent with only modest seasonal melt, it can behave much like a continental ice sheet would behave on the atmosphere (like in Antarctica). The jet stream exists because the Arctic atmosphere is cold throughout the vertical column. The strong temperature gradient with the mid-latitudes is what makes it exist. But with abrupt warming of the Arctic caused by the collapsing ice sheet (which feeds back on accelerating such a collapse), this weakens the jet stream and has been causing it to become wavier with increasingly more extreme and frequent high amplitude patterns (which feedback and melt the Arctic more). Such research has been conducted by scientists such as Dr. Jennifer Francis of Rutgers University and others, showing the jet stream slowing and becoming higher in amplitude since the 1960s. Such abrupt warming also leads events such as “sudden stratospheric warming” and “splitting” of the polar vortex, supporting Arctic blasts to the south and abundant heat transport to the Arctic.

If the ice sheet collapses completely (no more in summer, low to little meaningful extent in the polar night), you get even more abrupt warming of the sea surface from below and above through collapse of the ocean thermocline (persistently cold water “cap” atop somewhat warmer water) and air temperature inversion (warmer air atop cold surface air) as well as from the much reduced albedo (white, reflective surface). The warming atmospheric column with height further reduces the temperature gradient with the mid-latitudes, weakening the jet further and causing more extreme “wave action”, greater blocking patterns as you get these big waves and little eastward progression of systems and the polar jet actually retreats farther north. This can dramatically shift precipitation patterns northward could cause much hotter, drier conditions in the mid-latitudes. It’s been a major concern for a long time in in climate change science, but a process thought to be of concern in the “high emissions” scenarios of the mid to late 21st century as increasing aridity across the mid-latitudes would destroy forests and not allow crops to be grown where they are currently grown because of increasing extreme heat (or storms). So this would have impacts not only in the Arctic, but also in the mid-latitudes. Unfortunately, a recent phrase has been increasing use the past few years. “Faster than expected”. Some prominent researchers openly admit an ice-free Arctic may be possible before 2020. See also HERE.

I’ll have more on the situation in the Arctic this week as well as the heavy rainfall in the US. Also, keep an eye on Tropical Storm Gita approaching New Zealand to start the week!

–Meteorologist Nick Humphrey

The Story of Meteorological Fall-Winter to Date…Abnormal Heat/Increasing Dryness in the US

I thought it would interesting to look at the past 5 months (September-January) as there have been some notable trends at the seasonal level which have led to major impacts within the US. Some of this is driven by the cool phase of the El Nino Southern Oscillation (La Nina) in the tropical Pacific, while in the longer-term, they are being driven by increasingly more powerful influence of anthropogenic climate change on global temperatures and natural variability.

The most notable climate anomalies the past several months since the beginning of Meteorological Autumn (Sept 1st) have been very abnormal heat…particularly in the Western US and increasing dryness across much of the nation.

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Around two-thirds of the country is in at least abnormally dry conditions, with severe drought or worse rampant across the Desert Southwest into the Southern Plains and parts of the Deep South.

The rapid increase in drought conditions since late Autumn was initially caused by the jet stream favoring the northern tier states and southern Canada, with strong upper-atmospheric high pressure over the West contributing to the abnormal warmth. However, by January, the pattern changed with the jet stream becoming much more higher in amplitude over the US. The strong ridging remained over the Eastern Pacific and Western US, but strong dips in the jet stream have thus far brought abundant cold air masses into the center and eastern third of the country. These continental Arctic air masses have also been quite dry, making it difficult for many places to recover from drought conditions. In many cases, the situation has worsened. 

One thing to notice as far the heat is concerned for January 2018. Although there was a wide swath of the US with below normal temperatures, the 9 states out West had their Top 10 warmest January on record vs. no states with a Top 10 coldest. So even with a high amplitude jet stream opening up Arctic air to much of the US, high heat (by winter norms) still dominated the US average with the 35th warmest January on record, in the top 30% out of 124 years. In addition, Alaska witnessed very abnormal warmth. Barrow had its warmest November on record (more than 16 F above normal) while the whole state had its warmest January on record. Also in January, Ketchikan, AK measured its (and Alaska’s) highest daily January temperature on record of 67 degrees F in the Panhandle. While La Nina and other “teleconnections” (multi-month and sub-seasonal atmospheric circulation patterns) are creating conditions favorable for these abnormal conditions, anthropogenic climate change is clearly having an impact on the intensity of warm regions over cold regions and the tendency for more frequent drought conditions (and longer wildfire seasons), especially in the Western US.

It appears February will be a repeat of January, although it may end up warmer overall if long-term models work out. And with this, meteorological winter may end on very abnormally warm and exceptionally dry note.

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Precipitation Probability Outlook for Feb 15-21. Conditions are favorable for maintenance and expansion of drought conditions in the US, especially in the West.
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Temperature Probability Outlook for Feb 15-21. Very abnormal warmth expected to continue in the West and expand in Alaska and the eastern third of the country.

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–Meteorologist Nick Humphrey

2/11/18: Edited to add February 8th Drought Monitor.

Wild Ride – More Cold Intrusions into North America/Europe, Powerful Warm Storm Headed for Arctic Ocean Monday

This winter has been a fascinating one to say the least. Wild oscillations between very abnormally warm and very abnormally cold while other places are are just consistently very warm. Or perhaps just very dry. Much of this has been thanks to the current La Nina pattern in place over the Tropical Pacific. The atmospheric pattern leading to abnormally cooler waters over the eastern tropical region also lead to the promotion of strong high pressure systems over the Central North Pacific with unusually higher amplitude jet streams. This favors a polar jet aiming for the Pacific Northwest, northern tier and into the northeastern third of the country while the Southwest and Sunbelt see drier conditions.

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Conditions of at least “Abnormally Dry” cover over 67% of the Continental US. It is the most coverage in abnormally dry conditions since February 5, 2013. It is, interestingly, the 49th greatest extent of at least Abnormally Dry conditions on record out of 944 recorded weekly updates (over 18 years now). Conditions of at least D1 “Moderate Drought” coverage over 38% of the Continental US. It is the most coverage in D1 conditions since April 22, 2014.

Of note with this pattern regime has been the, at times, extreme nature of the jet stream amplitudes. They have driven very warm temperatures into the Arctic with record low sea ice across the Arctic Ocean, the warmest December on record across the state of Alaska, and record high temperatures in portions of the Southwest US in January with the aforementioned persistent drying and intensifying drought concerns. 

Meanwhile, significant Arctic intrusions have been impacting the US, particularly in January and more appear likely in February as “teleconnections”…patterns in global circulation which give clues toward a general weather regime for a region of the world…show signs of further intense extreme jet stream amplitudes with very strong upper-level high pressure systems blocking storm tracks over the north Pacific and Bering Sea, which downstream will mean a cross polar flow in the upper atmosphere of very cold air upper troughs and surface Arctic fronts and high pressure systems over northern Plains/Midwest into the Northeast US. The Deep South should escape as warmer air from the subtropics attempts to advance north and may keep the Arctic air at bay. Europe looks to also have periods of similar cold (and interior Siberia of course! Check out the incredible cold they had last month).

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Temperature Anomalies in the US (Sunday, Thursday) and in Europe (Monday). Widespread temps below freezing during the day in parts of central and Eastern US and central and eastern Europe during these cold periods. Very persistent warmth with highs in the 60-80s in the Southwest US.

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Powerful Arctic Ocean Storm Sunday-Tuesday

While the mid-latitudes get hit with Arctic cold, the Arctic is being pounded by significant amounts of mid-latitude heat. And now the computer models are pointing towards a major North Atlantic storm developing early this weekend, moving over Greenland and then into the middle of the Arctic Ocean Sunday night-Monday. This storm will be very powerful…as strong as any classic North Atlantic ocean winter storm, and will bring significant amounts of high winds, battering waves and high “heat” to the Arctic. How warm? Perhaps as warm as 50-60 degrees F above normal temperatures over much of the Arctic Ocean. This will mean highs near or just above freezing up to the North Pole!

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Temperature forecast by the Global Forecast System model for noon CST Monday showing near or above freezing temperature penetrating deep into the interior Arctic as a result of intense warm air advection.
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A significant sector of the Arctic Ocean will have air temperatures over 40 degrees F above normal (or higher) during the day Monday.

This storm is forecast to initially form southwest of the tip of Greenland and east of Quebec Friday and will beginning moving over Greenland Saturday. Sunday, the system will begin to impact the Arctic, with warm and moisture transport from the North Atlantic (all the way from the Azores!) increasing abruptly late-Sunday. By Monday morning, models indicate waves moving up the Fram Strait toward the Arctic may be as high as 30 ft in strong south-southwesterly flow. Over the sea ice sheet, the low pressure system will be intense as it emerges from Greenland…possibly sub-960 millibars with widespread wind gusts of up to hurricane-force likely over much of the interior Arctic Ocean east and south of the low on the Atlantic side.

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GFS depiction of the powerful low pressure system over the central Arctic Ocean on Monday. The European model has a similar strength low. Winds up to hurricane-force wind gusts and battering waves are likely conditions for the tenuous sea ice.
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Forecast significant wave heights for early Monday with the worst of it in the Fram Strait.

Why this storm is so significant is because the Arctic sea ice is continuing to undergo collapse because of anthropogenic climate change. If the Arctic climate warms to the point that it simply cannot support sea ice in the warm season, with the Arctic Ocean warming as a result of very low albedo (reflectivity to visible light which would otherwise limit warming) compared to white ice (or latent heat of melting/freezing, instead of heat going into warming the ocean directly), this will have dramatic effects on not only regional climate but global climate (I can go into greater details in this in the comments or provide resources). Generally this was something expected much later in the future, but may occur earlier than expected, although it is difficult to predict when exactly this will occur as it would be nonlinear and abrupt. However, as mentioned, ice volume and extent for ice are running at record or near record lows across the Arctic Basin. Some of these effects on albedo and heating have already begun to be felt over the past several years on the marginal seas which are beginning to become increasingly ice free during the warm season (Chukchi Sea, Beaufort Sea, Eastern Siberian Sea), but it’s important to not have the interior Arctic Ocean lose significant ice. Particularly in the winter, but it has been struggling just to freeze this winter! For more on recent sea ice developments see these videos by Paul Beckwith (M.Sc, PhD candidate; HERE and HERE).

In the meantime, while we have year to year variability…various teleconnection patterns, anthropogenic forcing (CO2, other gasses) is the most dominant regime on our climate and so even while I must emphasize weather is not climate…I must also emphasize that climate is a statistical distribution of weather events; and so extreme weather events which are increasing in frequency and magnitude are a sign of our climate shifting to more extreme conditions and in sensitive places (particularly cold climates like the Arctic), those shifts are incredibly noticeable.

–Meteorologist Nick Humphrey

Meteorological Analysis of January 22, 2017 Great Plains/Midwest Blizzard As It Happened

Here is a meteorological analysis I did on Monday of the blizzard which raked much of the Central Plains and upper Midwest from Nebraska and Kansas to Minnesota and Wisconsin with heavy snow and high winds. It was recorded around 11:30 am CST Monday. Those who follow me on my Facebook page (also see my feed on the sidebar) were able to see it right after it was uploaded, but I’m posting it here for those interested in hearing me discuss the event as it happened. Peak snow totals up to a foot and a half resulted in parts of Nebraska, Iowa and Minnesota. Lincoln and surrounding parts of the town only saw 2-3 inches but the totals increased dramatically not far west and north. We got off easy compared to the one foot and greater totals in northeast Nebraska. Winds gusts throughout the region peaked 45-60 mph. You can hear the noise of the high wind through my door in the video.

By the way, my son Bruce makes a guest appearance as he tries to turn off my computer while recording. Haha.

Strong Winter Storm Impacting portions of Plains and Midwest Early Week

A strong winter storm is pushing across the Great Plains tonight. North of the low will experience widespread blizzard conditions and heavy snow. South of the low milder conditions with rain.

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Infrared image, but with surface frontal analysis added, valid at 6 pm CST.

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Parts of far southern Nebraska, into Iowa have a tight gradient between little to no snow vs. heavy snow with high winds. An example…my location in Lincoln, NE where the National Weather Service is calling for 3-4 inches for the day Monday and just added the county under a blizzard warning after 24 hrs ago thinking the area would only receive up to 1 inch with gusty winds and much better travel conditions.

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A difference less than 24 hrs makes. Lincoln now expects up to half a foot of snow (see below) and places expecting 7-8 inches are now expecting 12-18 inches!

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The whole system has been trending southeastward in the models and in reality and so the official forecast has been trended slightly higher and significantly so in places of central and northeastern Nebraska which may get up to a foot with isolated amounts up to 18 inches! The bigger story are winds which may gusts 35-50+ mph across much of the north-central Plains during the night and during the day Monday. This will induce the blizzard conditions, with very low visibilities.

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Conditions will improve across Nebraska and South Dakota by tomorrow evening as the storm shifts northeastward, continuing to impact northern Iowa and southern Minnesota, as well as Wisconsin and upper Michigan with locally heavy snow and gusty winds.

If you’re in an area under blizzard or winter storm warnings, stay off the roads during the worst of the conditions unless absolutely necessary as the roads will be treacherous and visibility poor, particularly outside major cities, where snow can blow around easily. If you have to travel, drive slowly and with care.