11 a.m. or just after - I notice a considerable number of lighting strikes on the lightning tracker to the southwest of Santa Fe. And outside, the sky is very dark in the SW, with distant rumbles of thunder audible and even a flash of lightning along the southwest horizon under the dark clouds. The anvil of the storm is extended overhead from the storm to the SW, with an appearance not totally different from a summer thunderstorm. Storms are moving almost due S to N, with perhaps a small northeastward component.
Here is a radar image from 11:10 a.m. MST, showing the thunderstorm southwest of Santa Fe:
11:30 a.m. - I am thinking that if I can get to high enough an elevation for the p-type to be snow, I can get thundersnow. The temperature in Santa Fe is in the low 40s, but colder is air likely to be pulled down with precipitation, so in the areas getting precipitation, it is likely colder, in the 30s. The Santa Fe elevation of 7000 is borderline for rain or snow with this system, so I want to intercept the storms at a higher elevation. However, with the storms moving almost due north, it looks like they will pass west of the mountains. So after some indecision, I decide to intercept in the higher terrain (but not mountainous) north of Santa Fe along route 599.
Here is a radar image from 11:36 a.m. as the storms are lined north and south along the western fringes of the Santa Fe area, with the strongest cell in this line near the intersection of I-25 and route 599, moving just slightly east of due north.
11:45 a.m. - I am just north of route 599 east of Caja del Rio and west of Camino La Tierra - I had to go farther west than I anticipated to reach the mainly northward-moving storms; hoping p-type will be mainly snow or graupel/snow pellets to get thundersnow video. From 11:45 to 12:05, I get video as two cells in the narrow N-S line of convection move through. Main p-type is graupel/snow pellets with some ordinary snow also at times, and a little rain mainly at the start. With the precipitation, the temperature quickly fell to around 37 or 38 and stayed there throughout the time of my observations. There is lots of lighting and thunder, and I am lucky enough to get two bolts on video. Some of the lightning, either overhead or with nearby strikes, is less than 1/4 mile away. The heaviest precipitation passes to my west, so I didn't get real heavy snow or graupel with lightning and thunder, but it did afford me a better view of the bolts which I probably would have missed had I been in the core. Here are a couple video stills of the bolts I saw, with light graupel/snow pellets falling at the time:
Here is a radar loop from the time I was on the storm (11:45 a.m.-12:05 p.m.):
You can see in the radar loop that as the storm crosses route 599, there are two distinct cells in the line, something that was very evident to me as I observed the storms and which I discuss in the video linked below. Also, a very clear-cut updraft base was visible south of the southern cell of the two, with even a shelf-cloud feature along the leading edge near the edge of the precipitation core. Here is a picture of that feature:
The radar loop linked above also illustrates how thundersnow events in the mountainous regions of New Mexico and Colorado tend to be different from ones that occur in the Midwest and East. As you can see in the loop, the winter thunderstorm activity is intense and localized, like summer thunderstorms, as the storms track northward through the western part of the Santa Fe metro area. This is typical of winter thunderstorms in this region, which often occur ahead of Pacific cold fronts, east or southeast of the surface low pressure center. This contrasts with most thundersnow events in the Midwest and Northeast (except for ones associated with lake effect snow, which is yet another variant). In the Midwest and Northeast, thundersnow occurs most often in areas of heavy snow embedded within broad precipitation shields in the cold sector east, northeast, and north of the surface low pressure. They tend to be parts of widespread areas of snow and often are associated with very heavy snow accumulations. In contrast, Colorado and New Mexico thundersnow events tend to be more isolated, often fast-moving, and surrounded by clear sky. Hence, the snow, thunder, and sunshine at the end of the video in the second storm over the city. Because of this, it is very possible in New Mexico and Colorado to get thundersnow events that don't produce big accumulations (except in the mountains) due to the more isolated nature of the storms and their often-fast movement. Accumulations from these thunderstorms were relatively minor, less than an inch in all cases, in the immediate Santa Fe area, although larger accumulations did occur at higher elevations in the mountains, particularly the Jemez mountains during these storms. In the mountains, convective elements often persist for a considerable time where air is forced upward by the mountains. Winter thunderstorms in New Mexico and Colorado also ususally have graupel or snow pellets as the predominant precipitation type, though ordinary snow is usually also present in some part of the storm. Graupel forms when ordinary snowflakes accumulate rime, which happens as the updraft lifts the snowflake through supercooled moisture. These pellets, unlike sleet, are soft and easily crushed between your finger and your thumb. But they do bounce and make some noise upon landing. In an intense squall in the mountains, they can accumulate 1-3 inches per hour, though they usually do eventually turn over to ordinary snowflakes.
One other point of interest on the radar loop - note that another storm farther west appears to briefly take on supercell characteristics. This is the storm that is shown just west of the Santo Domingo Pueblo on the second radar still image above. In the loop, as it moves NNE toward Los Alamos, you can see that it forms what resembles a hook echo on its southern end and a "flying eagle" signature in its anvil region. Both of these radar signatures suggest that it may have briefly taken on supercell characteristics. Indeed farther east in New Mexico, in air considerably warmer than in the Santa Fe area, there was even one tornado warning near Clovis, NM, although no severe weather was reported.
These thunderstorms that I observed on December 27 were part of a multi-day event, marked by snow showers, thunderstorms, and short-lived bursts of snow in the valleys, but much more persistent heavy snow in the mountains. 3-day storm totals with this weather system ranged from around an inch in much of the immediate Santa Fe metro area to as much as 2 feet at Ski Santa Fe, 15 miles to the northeast but at much higher elevation.
12:10 p.m. - The heaviest core has now passed by and is to my north, so I head back toward Santa Fe. Parts of the 599 frontage road are covered with graupel and slush, as a new core intensifies just to my northeast. But it is moving away quickly, so I decide to head back to Santa Fe.
12:40-12:55 p.m. - Back in Santa Fe, I notice that another strong cell is moving north over the city. By the time I can grab my phone and go outside to get video, a bright, close flash of lightning has already happened; I manage to get started recording in time to catch the thunder as a mix of rain and snow falls. The precipitation then changes to graupel, and from there for about 10 minutes, back and forth between graupel and ordinary snow with several more rumbles of thunder. At the end, the sun is out with a little snow coming down and still getting rumbles of thunder, as noted above in the discussion of how thundersnow storms in this part of the country differ from those in other parts.
Here is a radar image showing this storm as it moved over the city:
Here is video showing both the storms I observed. The first part shows the line of storms I observed from around 11:45 to 12:10 northwest of Santa Fe a little north of route 599. The second part of the video shows the storms that moved over the city around 12:45:
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