April 8 – 10, 2013 Severe Weather Review:
If you were like me, you would have asked yourself where all the severe weather was in the Southern Plains on April 8th and 9th. Though there were some pretty significant storms that developed along and behind the cold front, few to zero surface based storms formed either of these two days. Why? In short, a very stout elevated mixed layer (EML) was in place over KS, OK and northern TX. This was the primary reason why storms had so much trouble getting going. Perhaps another blog for later. I suppose you can say my forecast was a busted forecast, for the most part, though there were some pretty severe storms in TX, OK and KS that produced some significant hail. If anything, those days were a very important lesson learned, for me.
April 10th and 11th proved to be pretty good severe weather days east of the Plains, for the Mississippi Valley and South. Together, these two days ended up producing 25 tornado reports, more than 100 hail reports and more than 300 wind reports. The environment was obviously better conductive for surface-based severe storms.
April 14-16, 2013 Severe Weather Outlook:
Given what happened in the previous severe weather event, I’m going to lean toward persistence, at least this time around. It proves that numerical weather models should NOT always be fully trusted.
Having said that, on Sunday, April 14th there will be a conditional severe weather event for northern OK and southern KS. There should be enough upward ascent to break whatever cap inversion that is in place by late afternoon. The main severe threats will be wind and hail. Storms should fire along a cold/stationary front. Usually, storms that fire along a cold front get undercut by the front and therefore the tornado risk is usually low. However, if there happens to be isolated, discrete cells that form, conditions will be favoring rotating updrafts.
Monday, April 15th looks to be a very interesting day. The numerical models disagree with the outcome of the day. Pretty much every model has a capping inversion in place over much of the Southern Plains, at least until sunset. GFS has been consistent on forming storms from northern TX/southern OK, into northwest AR/southwest MO and southern IL. NAM has a very strong cap in place over these areas by sunset on Monday, and shows nothing forming by evening. I’m leaning toward the NAM on this one, BUT if the cap does happen to break, storms will be in a rich environment for supercells to form, perhaps even a tornado or two, since these storms will be a head or along a stationary front that will stall over central OK. I will be interested to see what happens.
(EDITED) On Tuesday, April 16th, the cold/stationary front will still be stalled central OK. At first I believed the front would be through by early afternoon, but looking at recent runs of forecast models, it seems the front will still be stalled or moving slowly through central and northeast OK. Given this information, it looks as if storms that form a head of the front will be surface based. There will still be a cap over the area, initially. NAM is still silent with precipitation through Tuesday evening. Therefore, it believes the cap will hold strong. Latest CMC run is the same as NAM. If this is the case, convection will likely be behind and along the front. Perhaps a better chance of storms will be near the Red River or in western-north TX. This is where both the GFS and NAM show the cap to be the weakest. This is also the area where the dryline will be set up, another feature rendering aid for dynamical lift. Again, when it comes to mesoscale systems, numerical models are not something to depend on. Though, I think this will be the area to monitor the most on Tuesday afternoon and evening.
Forecasts can change fast, but as of late Saturday (13th) evening, this is my best guess as to what will happen in the next few days.