Friday 5/29/18 Forecast

I’ve been keeping a close eye on the setup for this Friday. The trough has continuously slowed down over the past week with the GFS (originally it was showing the trough Tuesday, then slowed down to Thursday), but the timing seems to be settling in over the last couple days with Friday being the day in the plains. Now that we’ve seen a little consistency out of the GFS, I think it’s somewhat safe to start talking details. I have not been watching the euro and now that I say something about the GFS settling in it will probably shit the bed with the 00Z run (hasn’t come out yet as I type this).

A low amplitude trough will eject into the plains Friday. Although there isn’t much curvature, the midlevel jet is fairly strong with the shortwave that will move through Kansas Friday afternoon. Moisture quality is always a concern this time of year and although the GFS shows dewpoints getting into the low 60’s as far north as south central Kansas, I’m not sure I’m buying that quite yet. The Gulf is going to get hammered and dried out for the next 48 hours before trajectories turn around and start pulling moisture back in off the western Gulf around Thursday morning. That leaves 36 hours for a decent fetch of moisture. The low level is going to be fairly strong, but again I’m not sold on dewpoints reaching the low 60’s quite yet. I only looked at a couple forecast sounding since we’re still a long ways out, but the moisture in south central Kansas was pretty deep. The focus for convection will be along a cold front across central Kansas, but I’m not paying attention to that. I’m after tornadoes, so my focus is on the cold front dryline interection/triple point and the dryline south from there. The triple point looks to be fairly close to Wichita Friday afternoon with the dryline running south from there along the I35 corridor. The GFS has been very sparse with convection. It’s shown a little precipitation off the triple point, but it’s only showed occasional blips along the dryline into Oklahoma. I don’t trust any of the models on precipitation, but it would be nice to see that trend change. There is a pretty stout cap on some of the forecast soundings, so convective coverage is a concern with this one. We may not see any storms away from the cold front. My guess is we’ll get a triple point storm and maybe a dryline storm or two, but they could struggle. The few soundings I looked at had very little CAPE in the lower levels, which I’m never a fan of. I also hate veering 850’s, which also looks to be the case with this setup. If you’ve read my forecast posts much at all then you’ll already know there are few things I dislike more with a plains setup than veering 850’s. At 21Z the GFS shows decent veering in the 850-500 layer, but by 00Z there’s straight line hodographs over over south central Kansas and farther south where there is still a little veering in that same layer the cap/convective coverage looks to be an issue. The timing isn’t good with the cold front either. Earlier in the day you have more of a warm front style boundary east of the triple point with backing surface winds, but it’s starts to transition to a cold front style boundary later in the afternoon with surface winds weakening and starting to veer as the front moves south. That’s never a good thing for low level shear and tornado potential with storms tracking near the front, which includes the triple point storm. I’m keeping a close eye on it, but right now I see a lot of problems for tornado potential. Low level lapse rates aren’t good, advancing cold front, convective coverage issues along the dryline, lift north of most of the warm sector, veering 850’s, etc. I am prepping to chase and likely will, but I’m not all that excited about my prospects of seeing a tornado at this point. I’ll get a map and more detailed forecast posted in the coming days. Right now I’d target the triple point in south central Kansas. If it looks like the dryline will fire up then there may be better prospects down there with more favorable shear profiles.

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