Levelland, TX February 3, 2022
7” of snow in Jayton, TX – Feb 3, 2022
To kick February off this year, Winter Storm Landon or “Groundhog Storm” as aptly named by Twitter brought everything from snow, ice, freezing rain, and hail to 5 tornadoes (3 EF2). This system was quite the start to a La Niña winter, in which the southern United States typically sees warm, dry winters due to the high-pressure system in the Pacific (exacerbated in-part by ocean circulation) driving the Polar jet stream more north during this time. After a rough winter last year, Texas was hopeful that this La Niña winter would not bring the same snow/winter/ice mix. However, the polar jet had some tricks of its own.
300mb Jet Analysis Map – Storm Prediction Center Archive NOAA – Feb 3 2022
In Figure 1, we can see the polar jet had indeed decided to grace the lower latitudes and the subtropical jet with its presence, as we can see a large trough axis over west Texas with a slight negative tilt (see red dashed line). This tells us that the polar jet is bringing that cold air from the north along with strong wind speeds and shear aloft as evidenced by the wind barbs. The negative tilt suggests that the cold air is advecting over the warm air below, which leads to thermodynamic instability and vertical movement of air which produces strong thunderstorm and precipitation events. The negative tilt also indicates that the Low-Pressure System we see in Figure 2 has reached maturity.
NOAA Surface Analysis Map February 2-4, 2022
In figure 2, we can see the strong high-pressure system (HPS) in the North driving the low-pressure system (LPS) southeast, through Texas and all the way up to Maine. From February 2nd to the 3rd, when most of the snowfall and wintery mix prevailed, we see the cold front ahead of the LPS crossing through TX. At 1631 Zulu (10:31 AM CST), we can see the wind barbs increasing in wind speed as the system brings in winds from the Northwest. From the tightly packed isobars, we can also see a strong pressure gradient forming, indicating high surface winds as the LPS moves through. From the 3rd to the 4th, we can see the LPS pushed out and the HPS moves over TX, clearing up the wintery mix and bringing warmer temperatures in the coming days.
We can also observe Landon’s winter mix via satellite imagery from the GOES satellites. In Figure 3, we see the GOES water vapor imagery over TX on February 2nd from 8-9pm. The blue represents moist air whereas the yellow/orange represents dry air. We can see the advection of moist air over the dry air as well as a strong moisture gradient between the moist and dry air masses, adding to thermodynamic instability and vertical motion. The white and greenish colors represent thick, moist cloud tops which display the vertical motion of the air over TX as the LPS blanketed the lone-star state with snow and a wintery mix.
GOES Band 9 Water Vapor Imagery (6.9μm)
We can also see the more traditional satellite view of the GOES-16 GeoColor Visible image of TX on February 3rd at 12:46PM below.
GOES-16 GeoColor Visible(Daytime) – CIRA – Feb 3 1646 UTC [Full timeline link here]
This image shows Winter Storm Landon in all its glory, stretching from Texas to Maine. The white we see are the high cloud tops over the affected areas, which indicates thermodynamic instability and the storm or precipitation type can be inferred from a combination of local atmospheric dynamics and other satellite products. In other words, this picture is great at showing Landon’s extent, but we need a little bit more information to identify where the snow/ winter mix actually is.
For that, we’ll turn to another GOES product known as DayCloudPhase.
GOES-16 DayCloudPhase – CIRA – Feb 3 1651 UTC [Full timeline link here]
The DayCloudPhase is a helpful tool because it provides insight to the differences between cloud and land reflected temperatures in visible and infrared, which allows us to distinguish between snow/ice on the ground versus cold cloud tops. This image is from the same time as the GeoColor above. The green indicates snow on the ground, which we can see in North TX and the cyan color indicates low level clouds with water droplets, which can indicate precipitation (snow, ice, freezing rain, rain, sleet) depending on the lower-to-mid-level atmospheric processes occurring at the time. On February 3, we saw that most of mid to North TX experienced snow and a wintery mix and we can confirm that by looking at this image along with the dynamics at play. The orange indicates the thin, high level ice clouds. NOTE: The red in this image simply indicates that this image was almost in night mode, as it switches to infrared at night, which is not very useful to us.
We know that the snow and winter mix also occurred during the evenings, with much occurring the night of Feb 2-3. What do we use at night then if the other products are only helpful during the day? For that, we turn to the Nighttime Microphysics GOES channel.
GOES-16 Nighttime Microphysics – CIRA – Feb 3 03:01 UTC [Full timeline link here]
This channel allows us to observe various cloud types in the mid to upper troposphere during the night. The red indicates high, thick clouds and when these also have yellow coloring it indicates that these clouds are very cold, which are indicative of strong vertical development and instability (hint: compare this image to the GeoColor Visible). The light green/yellow indicates mid water clouds, indicative of some type of precipitation in the context of this winter event. From this image and with the prior knowledge of dynamics occurring at this time we can view Landon’s winter mix moving over Texas even during the night.
Finally, we can also confirm Winter Storm Landon’s effect on TX by looking at radar reflectivity.
Base Reflectivity – NOAA SPC – Feb 3 AM
In this radar image in the morning of Feb 3, we can see the snow (light blue to green) and winter mix (blue/green – especially in the streaky areas). We can see how heavy the precipitation is based on the color reflected as well. Blue/green shows light precipitation (in our case snow/winter mix), whereas yellow shows moderate, and red indicates heavy precipitation (in the case you see over Mississippi the red is heavy rain and some thunderstorms), We’ll look more closely at the radar images from Lubbock, TX to get a sense of the precipitation in North TX specifically.
Figure 8 – Lubbock TX
Base Reflectivity – DuPage Feb 2 2200-2221 UTC
Feb 3 2200-2223 UTC
Lubbock, TX Doppler Radar
From the Lubbock, TX doppler radar on Feb 2 PM (left) we can see the reflectance of snow (blue, possible green) and winter mix (blue/green) as the LPS begins to pass through. We see the same on Feb 3 PM (left), with some interesting backsliding of snow as the system is moving out. We can also identity some anomalous propagation or “noise” on these radars, with the little circle of (red/yellow) along with some of the stringy grey in the middle of the left image. This is most likely buildings of nearby cities reflecting or bouncing the radio waves back, creating an image that would look like some sort of severe storm formation, but is more likely a false echo due to its size, lack of movement between days, and in context of what we know regarding the dynamics at play. This can be cause by trapping of radio waves in ducts, due to surface inversions or inversions aloft or drastic decreases in water vapor pressure with height.
Overall, Landon brought rain, freezing rain, sleet, ice, and snow to TX, with some areas of North Texas seeing 8”! Certainly, Texas was once again not prepared for this, as many (~350,000 people) did lose power for a brief time, but Landon did not do quite as much damage as last year’s Winter Storm Uri. Considering this was supposed to be another mild La Niña winter, maybe Texas should really start to winterize in time for next winter.