Tornado Forecast

May 6th Forecast Map

Above is my updated map for Saturday and Sunday. It is looking unlikely that I’ll chase tomorrow. I found out this afternoon at work that I have a conference call first thing Monday morning that I have to get some work done for so unfortunately Mikey will be going into work tomorrow morning. Low level shear doesn’t look as good as it did a day or two ago anyway, so I’m not too upset. I think the tornado threat will be lower end tomorrow, plus Sunday is looking like it may be capable of a strong tornado threat so it’s not a huge deal sitting tomorrow out. It was going to be rough driving all the way up to NE Colorado tomorrow and then heading back south to west central Oklahoma Sunday morning and then back home to Wichita late Sunday night anyway.

For tomorrow my thoughts are the same, minus I think the tornado threat has trended down over the last 24 hours with the models. Dewpoints don’t look quite as good with maybe low 50’s wrapping in around the surface low and mid 50’s a little farther east closer to the Nebraska panhandle/far northeast Colorado. That small drop in moisture quality along with low level shear looking a little weaker lowers the tornado threat a bit. I think there’s a decent chance we’ll see a tornadic storm or two tomorrow, but I think they’ll produce weak tornadoes.

I still think there are two good targets tomorrow. The most sure thing seems to be NW/N of the surface low where a storm or two should fire first. For that target I’d probably setup just north of Denver. I think you’ll get a couple storms firing early in that area and I’d get on a more dominant cell if there isn’t just one tracking north through that area.

The other target would be a little farther east off the north side of the dryline bulge. For that area I’d setup a county or two southwest of the far NE corner of Colorado. You should get an arcing band of storms developing through there and wherever there is more of a tail end or break in the line over that eastern portion of the area is the storm I’d want to be on for that target.

Sunday is looking better with both the NAM and GFS 00Z runs IMO. As a matter of fact, I think strong tornadoes are starting to look like a real possibility, especially if we can get mid to upper 60 dewpoints ahead of the dryline in west central and northwest Oklahoma. That’s what the NAM is currently showing, with the GFS backing off that a few degrees.  I still think it’s tough to narrow down any particular area quite yet given the uncertainties around moisture return and morning convection potentially disrupting portions of the target area though so I may adjust my target tomorrow. The most intense storms should develop along a dryline that should lie roughly along a Dodge City, KS to Childress, TX line by late afternoon. The extent of storm coverage is a bit uncertain along with the exact location of the dryline. My best guess is that we’ll see several discrete supercells through that corridor. Storm motions are very much perpendicular to the dryline, so storm motions/boundary orientation are quite favorable for discrete supercells. Any place we get decent clearing during the afternoon, (which looks to be along most of the dryline in the area I outlined on the map) should develop moderate instability by afternoon. Moisture quality obviously plays a big role in how much instability we get, so again moisture return and realizing dewpoints in the mid to upper 60’s is important here. Deep layer shear will be fairly strong, so updraft/downdraft separation should not be a problem and conditions will be quite favorable for supercells if we get moderate instability.SR mid-upper level winds are fairly strong, so we should be looking at classic supercells, which is a relief after dealing with HP storms several times this year. With tonight’s 00Z runs, low level shear is quite impressive.

On tornado potential, forecast soundings/hodographs with the NAM are quite impressive, especially along and either side of that I40 corridor in west central Oklahoma, which is kind of a target area I’ve been looking at for a couple days. 0-1km SRH is AOA 200 ahead of the dryline in central Oklahoma, which is getting up into strong tornado territory. LCL, heights will also be fairly low if we can get upper 60 dewpoints. Worst case scenario LCL heights at least seem workable on Sunday.  Below is a forecast sounding from west central Oklahoma.

00_NAM_048_35.5,-99.04_severe_ml

If we can get mid to upper 60 dewpoints with the moderate instability that’s currently being forecast, I think a strong tornado threat will exist across the area I outlined on the map. I’m curious to see how SPC handles this. They are probably still a little hesitant to get too aggressive with the forecast given some of the uncertainty involved with Sunday since the outbreak media ass kicking they took two weeks ago Tuesday is still fresh in their minds lol. If they don’t go to an enhanced risk tonight, I’d expect to see it tomorrow afternoon if the 12Z runs stay on track with tonight’s runs.

I’ll update again early tomorrow afternoon so check back then if you’re interested.

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