Royce Sheibal
EF3
No April Fool's here, there might be some storms to chase on Wednesday.
SPC has dropped a SLIGHT across much of the Missouri Valley for Wednesday afternoon. Local office discussion has a mention for 2-3k cape and deep layer shear, supporting a forecast for severe weather. This leaves me with two major questions. 1: Will there be enough moisture return? 2: Will storm motions (forecast to be ENE), be far enough away from the squall / LCS to maintain rotation?
I don't think shear will be a huge issue. NAM was very bullish last night, with 1k EHI's in the 3-5 range in E Neb, but has pulled back quite a bit on the 06z and now the 12z. GFS has been a bit less eager to forecast shear, but there is still enough given the cape now forecast. As for moisture, based on the speed of the 850's I think that a 60 dewpoint is possible ahead of the main line, and 60 is a good cutoff in Nebraska for TORs (possibly even lower due to the LCL's that are forecast to be <1000m.)
Storm motion is going to be the tricky one here. Cell speed will likely be slower than the LCS, and ENE motion is barely off of the expected SW/NE orientation of the front. Inflow and shear may be compromised by the proximity or cannibalized by the line. There is enough 3k helicity to support supercells, possibly weak tornadoes, but cells will likely only maintain rotation if they can form ahead of the main line in W IA, far SE Neb, or Ncentral KS.
Your Best Chance of a Tornado Wednesday: Tail - End Charley in Scentral NEB / Ncentral KS. (Hebron, NE)
Although dynamics may be a little better to the north and east, it will be a mess up there, in particular if there is AM precipitation leftovers. Don't forget low LCL's means rain-wrapped HP's if cells do hold together. I'm not super confident that we'll even get a TOR at all Wednesday, but for many of you this will be the first or second chase of the year, so why not? Sadly I'm working.
SPC has dropped a SLIGHT across much of the Missouri Valley for Wednesday afternoon. Local office discussion has a mention for 2-3k cape and deep layer shear, supporting a forecast for severe weather. This leaves me with two major questions. 1: Will there be enough moisture return? 2: Will storm motions (forecast to be ENE), be far enough away from the squall / LCS to maintain rotation?
I don't think shear will be a huge issue. NAM was very bullish last night, with 1k EHI's in the 3-5 range in E Neb, but has pulled back quite a bit on the 06z and now the 12z. GFS has been a bit less eager to forecast shear, but there is still enough given the cape now forecast. As for moisture, based on the speed of the 850's I think that a 60 dewpoint is possible ahead of the main line, and 60 is a good cutoff in Nebraska for TORs (possibly even lower due to the LCL's that are forecast to be <1000m.)
Storm motion is going to be the tricky one here. Cell speed will likely be slower than the LCS, and ENE motion is barely off of the expected SW/NE orientation of the front. Inflow and shear may be compromised by the proximity or cannibalized by the line. There is enough 3k helicity to support supercells, possibly weak tornadoes, but cells will likely only maintain rotation if they can form ahead of the main line in W IA, far SE Neb, or Ncentral KS.
Your Best Chance of a Tornado Wednesday: Tail - End Charley in Scentral NEB / Ncentral KS. (Hebron, NE)
Although dynamics may be a little better to the north and east, it will be a mess up there, in particular if there is AM precipitation leftovers. Don't forget low LCL's means rain-wrapped HP's if cells do hold together. I'm not super confident that we'll even get a TOR at all Wednesday, but for many of you this will be the first or second chase of the year, so why not? Sadly I'm working.