A big storm system will deepen east of the Rockies and move across the Plains, bringing with it big weather impacts. On the south and east side of the system, severe weather is likely with a definite risk for tornadoes. On the north and west side, a snowstorm/blizzard that will probably have major impacts across the Northern Plains.

Monday: Late Night Threat

Most of the day on Monday will be characterized by deepening moisture profiles across the Plains as the storm system strengthens as it emerges east of the Rockies. By sunset, a favorable airmass will be in place for some severe weather, especially across Western OK into Northwest Texas.

  • Storms will likely form well after dark, perhaps as late as 2-3 a.m.
  • These storms will move east through the morning hours.
  • The severe weather threats would be some marginally severe hail early and damaging winds with the line that forms. A very low tornado risk will also exist for mesovorticies that might form within the line.

Tuesday: More Significant Threat

Tuesday is the ‘main event’ day of this storm system. The low will be rapidly deepening across the central/northern Plains with a cold front rapidly advancing across the south. Storms will likely be ongoing at the beginning of the day and will probably persist in some form all the way through the day and into the night.

  • Storm mode is going to be a big key. There will certainly be a line along the advancing cold front, but will there be isolated supercells ahead of that line?
  • If you do get isolated supercells, strong and long-track tornadoes are a very real threat.
  • There will be at least some tornado risk even along the line associated with short-lived mesovorticies.
  • A big snow event is likely across the Northern Plains on Tuesday into Tuesday night.

 

Storm mode is going to be the big key on Tuesday to be sure. If you can get some cloud breaks and heating ahead of the line, the wind shear is there for a big tornado event.

 

As of right now, the instability looks on the marginal side of things, but the thing about low CAPE events is a little bit of sun goes a long way this time of year. The difference in cape of 750 j/kg and 1500 j/kg is not that high and would be a huge difference maker. We won’t fully know this until perhaps the morning of.

 

The environment looks very robust, with ample wind shear across the entire atmospheric column. The big question I think is the degree of heating and thus, the possibility of isolated storms ahead of the line. This is a very typical question of systems this time of year. It is worth asking, but every big event in December/January has some of these questions beforehand.

 

One thing I’m curious about at the time of this writing is how the main forcing being more north and west might affect storm mode. This *could* actually mean a more cellular vs. linear mode at times. But that’s just this author’s curiosity that I’m just speculating about.