While much of the weather world on 23 February 2026 has turned its eyes to the east coast of the United States due to the presence of a strong bomb cyclone and an associated blizzard in the most densely-populated region of the country, the effects of this event are being felt much further out. One of the more unexpected impacts is the presence of lake effect snow in the northern part of central Indiana, nearly a hundred miles from the shore of Lake Michigan.

The impact of the Great Lakes on snowfall totals is well-known. Generally westerly flow across the Great Lakes causes higher snow totals on the eastern edges of those lakes to have notably higher annual snowfall totals. This is because the (relatively) warm and moist lakes inject sensible and latent heat into air that passes over the lakes. Those air masses then increased surface friction and terrain once they reach the shore, factors which cause low-level convergence and orographic lift which combine to help increase the low-level snowfall formation process. A map is available here from our friends at NOAA’s Great Lakes Environmental Research Laboratory; note how the downstream side of each of the Great Lakes hosts a local maximum in annual snowfall.

But what happens when the wind pattern isn’t the standard west-to-east flow that we see throughout much of the year?

The 700 hPa map from 1200 UTC on the 23rd gives an easily accessible overview of the synoptic state of the atmosphere on this day. The obvious weather maker is the cyclone off of the east coast of the continental United States, with a broad ridge across the western US. Over the Great Lakes, flow is almost due northerly.

The northerly flow across the Great Lakes is forcing lake effect snows in places that don’t always receive them. In particular, the fetch across Lake Michigan runs nearly the entire north-south extent of the lake. This puts a substantial plume of lake effect snow into northern and north-central Indiana. We’ll start our analysis with a true color view from the GOES-19 ABI as shown by SSEC’s Real Earth. The telltale signs of lake effect snow are present as narrow parallel bands of cloudiness forming over the lake, extending over the shore and penetrating into the land. But instead of the east-southeast orientation that is typical for Lake Michigan, the bands are almost straight north-south.

The Day Microphysics RGB can provide some insight to the makeup of the clouds producing these snows. The central band of cloudiness extending southward from Lake Michigan shows a lavender center where the clouds are geometrically thicker and a yellowish-green edge where they are thinner. Both of thse colors are associated with liquid clouds in this RGB, with the pinker colors representing clouds with larger water droplets. This is consistent with lake effect snow, as these clouds are much more shallow and closer to the surface than synoptically-forced clouds and thus are likely to be too warm to be purely ice clouds.

The Cloud Phase RGB similarly depicts a salmon-colored band where the clouds are liquid and have larger water particles, both of which are consistent with lake effect snowfall.

The Day Cloud Phase Distinction RGB also provides a unique perspective on the evolution of this event. Here, snow covered grown shows up s a bright green color. The wide swath of snow from last week’s event is clearly visible stretching from eastern Nebraska into north-central Wisconsin, for example. However, you can also see the surface snow cover in Indiana between the individual clouds of the lake-induced convection. The green and orange clouds assoicated with the thick ice clouds of the east coast cyclone are also visible on the far eastern edge of the image.

Finally, here is the 0.64 micron (red) visible satellite product with the Warsaw, Indiana NWS NEXRAD radar overlaid on top ot if, along with the surface weather conditions. The finer horizontal resolution of the 0.64 micron imagery really shows how small individual convective elements in a lake effect event can be. Persistent northerly winds ensures a constant flow of moisture and snow into the central part of Indiana. Based on this view, there’s clear lake effect influence as far south as Kokomo, meaning that town is hardly a tropical getaway today.

However, lake effect events are notoriously shallow. It is likely that the lake effect snow is propagating even further to the south, but after it reaches a certain distance away from the radar, the angled radar beam is overshooting the top of the snow rendering it invisible to that radar. If you also include the radar from the more southerly Indianapolis office, you can see individual lake effect precipitation echos penetrating as far south as the northern suburbs of Indianapolis, over 120 miles away from the Lake Michigan shore.

Lake effect events in northern Indiana aren’t altogether rare. South Bend, Indiana, and Joliet, Illinois are two cities at similar latitudes and similar distances away from Lake Michigan. However, South Bend’s position downstream of the lake contributes to its much higher snowfall of nearly 65 inches a year compared to Joliet’s annual snowfall of only 16 inches. However, the inland penetration of today’s event is certainly unusual, thanks to a stronger than normal flow over Lake Michigan that is almost perfectly oriented to maximize the influence that this lake can have on the regional weather.

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1-minute Mesoscale Domain Sector GOES-19 (GOES-East) Nighttime Microphysics RGB + daytime True Color RGB images from the CSPP GeoSphere site (above) showed the formation of a long power plant plume (nighttime shades of red) embedded within a supercooled water droplet cloud layer (nighttime shades of yellow) that grew in length and width as it moved southeastward across southern Wisconsin on 21 February 2026. The power plant plume had the effect of eroding the supercooled water droplet cloud layer — via glaciation, initiated by the power plant emission of particles that acted as efficient ice nuclei — which then caused snow to fall from the cloud (leaving holes and thin cloud segments that were very apparent in True Color RGB images).

A toggle between the GOES-19 Night Fog Brightness Temperature Difference (BTD) image and Cloud Top Phase derived product at 1200 UTC (below) confirmed that the cloud layer across southern Wisconsin was composed of supercooled water droplets (lime green enhancement).

1-minute GOES-19 Night Fog BTD + daytime Visible images (below) suggested that the Columbia Energy Center in northwest Columbia County was the source of the power plant plume.

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The evening of 19 February featured a rare-for-the-midwest winter tornado outbreak. Tornadoes were reported in several locations in southern Illinois and Indiana, accompanied by numerous reports of hail and damaging winds. Much of the severe weather happened after dark as well. Multiple tornadoes were reported across the two states, with the most significant being an EF2 tornado with a nearly four mile long track in the western part of Bloomington, Indiana.

Earlier in the day, rain from morning thunderstorms moistened the region (see this blog post about those storms). Dew points rose from the low 50s to 60 degrees or more. After the morning storms dissipated, daytime heating caused temperatures to reach 70 in certain locations, providing ample energy for vertical motion. As noted in the earlier blog post from this day, this region is at the heart of one of the nation’s largest radiosonde gaps making it hard to know how the atmosphere may be destabilizing. However, NUCAPS profile retrievals can really help to fill in where conventional observations are lacking. Here is a NUCAPS satellite-based vertical profile from near Bloomington, Indiana, in the south-central part of the state. This profile was obtained from the always excellent NUCAPS Savvy site operated by NASA SPoRT. This is from the NOAA-20 polar orbiting satellite overpass around 1900 UTC, or 2:00 PM ET.

At first glance, the profile doesn’t seem to provide a whole lot to be concerned about. The mixed-layer cape is only 54 J/kg, far below values that we’d expect to be supportive of deep moist convection. The most unstable cape isn’t much better at 227 J/kg. Still, there are some interesting things here. First, the DCAPE is rather robust at 603 J/kg. Remember, one of the limitations of NUCAPS profiles is that the retrieved vertical structure is much smoother than truth: inversions and moist layers are sanded down compared to what you would see on a radiosonde. Therefore, this DCAPE value is likely high enough to support strong downdrafts and significant outflow winds. The next thing to note is the array of low-level lapse rates in the bottom right of the figure above. Those are all steeper than you might normally expect for a winter’s day in Indiana, and indicate that instability might be present despite what the CAPE values say. Finally, the NUCAPS-retrieved surface conditions can often be an underestimate of the true environment, especially for the dew point. At 2:00 PM, the Bloomington Airport (KBMG) reported a surface temperature of 66 F (19 C) and a surface dew point of 57 F (14 C). The surface temperature as seen by NUCAPS is quite good, however it really underestimated the dew point. If you assume a 14 C surface dew point in the above sounding, you would get a remarkably larger CAPE value. (The impact that making the simple change to observed surface values can have on satellite-derived measures of instability is explored in this paper by CIMSS and SSEC researchers).

It’s worth looking at those lapse rates some more. The Gridded NUCAPS product allows us to see the spatial distribution of NUCAPS-derived values. Here, for example is the 850-500 mb Gridded NUCAPS lapse rate from the NOAA-20 overpass as captured by the NASA SPoRT Viewer. Note all the light greens and yellows in central and southern Indiana. It looks like those 7+ C/km lapse rates are quite common throughout the region, implying that there’s actually some widespread instability.

The same polar orbiting satellite that gave us the NUCAPS data also provides observations of total precipitable water (TPW) from the ATMS instrument. This image was obtained from the direct broadcast antenna here at CIMSS and SSEC, and shows the relatively moist environment over the southern parts of Illinois and Indiana, with TPW values exceeding 30 mm.

The following loop shows the evolution of the environment from 1100 UTC (6:00 AM ET, 5:00 AM CT) through the tornadic period on to 200 UTC (9:00 PM ET, 8:00 PM CT). Initiation occurred along an advancing frontal boundary. One of the interesting things to see about this event is that the convective clouds are relatively shallow. Normally, you’d expect to see much colder cloud top temperatures for tornadic storms but these seemed to reach only about -50 C or so. This isn’t a case of an extremely low tropopause, as the 00 UTC sounding from Wilmington, OH (near Cincinnati) showed a tropopause temperature of -60 at a pressure of around 210 hPa. Instead, these are clouds that just didn’t grow to their maximum possible height. However, with those low level lapse rates being what they were, perhaps they didn’t need to.

As an even that spanned the transition from day to night, many of the most popular satellite RGB products for detecting convective development were losing their utility. This is because those products depend on near-infrared reflectance or emission, and once the sun sets those values go close to zero. Still, there are a pair of RGB products worth investigating. The first is the Air Mass RGB. Normally, it’s used for more dynamical applications, like identifying regions of potential vorticity or stratospheric intrusions. However, at a glance it can also inform about the distribution of different air mass types in a region. The warmer and moister air masses are green, while the colder and dryer air masses are blue. Where the colors shift rapidly over a small difference can be indicative of a front. Based on this, there appears to be a north-south boundary along the southern Mississippi River and into eastern Illinois at the start of the following animation. As this pushes eastward, convection fires along that boundary in the region of the country that we already identified as having widespread instability from the Gridded NUCAPS lapse rates. An advantage of this product is its 24/7 utility since it only depends on longwave IR bands that are not impacted by the presence or lack of solar radiation.

The Night Microphysics RGB is a go-to standard for any meteorologist working the night shift. The deeper convection is found in the regions with red or speckled yellow coloring. While perhaps not as useful as some of the daytime products in identifying the regions that are about to experience rapid vertical development, it is still well-suited for keeping abreast of where the most significant weather is taking place. Note that sunset in southern Indiana was around 6:30 PM local time (2330 UTC) and the Night Microphysics RGB depends on the 3.9 micron channel whose interpretation changes immensely between day and night. Therefore, you can only use this product at night which means only the latter part of this animation is truly useful. Still, at the end, we see numerous modestly deep cells across the middle of Indiana as well as stretching from southeastern Iowa into southeastern Illinois.

To provide some additional context to this event, here is the radar-observed reflectivity and storm relative velocity over Bloomington from the NEXRAD radar in Indianapolis. The strong gate-to-gate shear indicates a strong mesocyclone that can be associated with tornadic activity. The Indianapolis NWS office issued a rare Particularly Dangerous Situation (PDS) warning for this event, in part based on the strong rotation seen in the radar.

The CIMSS ProbSevere product was also useful for this event. The red polygons note the location of tornado warnings issued by the NWS Weather Forecast Office in Indianapolis, while the contours note the locations of ProbSevere-identified areas of potential severe weather formation. The contour within the tornado warning polygons showed that ProbSevere predicted a 75% chance of severe weather within that contour, including a 59% chance of a tornado. The Monroe County Airport just outside of Bloomington recorded a 70 mph wind gust before losing all observations due to lost power.

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While it may be winter, unseasonably warm conditions on February 19 were able to support convection across portions of the midwest and into southern Ontario. Convection began firing at multiple locations, including metropolitan St. Louis, Missouri; northeastern Indiana, and southeastern Illinois. To start with, let’s look at the 1500 UTC (9 AM CT, 10 AM ET) surface map as analyzed by NOAA’s Weather Prediction Center. Here, a weak frontal boundary stretches from Ohio southwesterly to a center of circulation in northeastern Kansas. Along and south of this boundary, conditions are quite moist for this time of year with dew points in the mid to upper 50s. There’s also evidence of a weak shortwave at 500 hPa over southern Illinois and western Kentucky that could be abetting any convection that develops (see here).

This can be a challenging part of the country for upper air observations as one of the nation’s larger radiosonde gaps is found between Lincoln, Illinois; Nashville, Tennessee; and Wilmington (suburban Cincinnati), Ohio. Still, looking at some of these soundings can tell us some things. The morning sounding from Nashville, for example, shows small amount of CAPE, which, when assisted by some weak upper-level dynamics, can cause some deeper convection to take place.

The GOES-19 mesoscale sector was active over the region, enabling a fine-scaled view of the evolution of these systems. We’ll start with the Day Cloud Phase Distinction RGB. This product is well-suited to identifying fast-developing cumulus which can quickly evolve into deep convection. The congested clouds transitioning from green to yellow are the cells to watch, as green represents glaciating clouds and yellow notes thick clouds with ice particles which are consistent with deep moist convection.

Similarly, the day convection product can help identify locations where convection is developing. Yellow spots indicate where strong updrafts are taking place, as this is where both cold cloud tops and small ice particle size (associated with young convection) are found. Here, we see that actively developing storms are taking place in northeastern Indiana, south-central Michigan, the Ontario peninsula, and the southern part of the Indiana/Illinois border.

Let’s take a closer look at the development of the cell on the Illinois/Indiana border. The following animation depicts both the day cloud phase distinction (top) and day convection (bottom) RGB products. The CIMSS LightningCast product has been overlaid on both RGB products. There is an existing area of convection on the western edge of the image, while the new cell can be seen developing in the middle of the animation. The first contours of lightning probability from LightningCast are seen at the same as the signs of convection (yellow and green in the top, yellow on the bottom) in the RGBs.

When AWIPS renders animations, the colorization can appear somewhat muted. Here’s a single frame from the above animation that better depects the colors as they are seen in AWIPS or SSEC RealEarth.

Additional convection is expected later in the day in this region as the first round moistened the environment and continued heating is expected to further destabilize the atmosphere.

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