6/5/08 FCST: TX/OK/KS/NE/MN/IA/MO

[Mike Smith]

A 990mb low in the Panhandle area the first week of June?

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_slp_156m.gif

With 110+ kt. 250mb winds? www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/12/images/gfs_250_156m.gif

If this verifies, a major outbreak is possible.

 

[Derek Weston]

GFS has been waffling around in position, but I've noticed this storm for a while now. Currently has the Eastern half of Kansas as tornado fest.

 

[Michael O'Keeffe]

Looking at the GFS I agree this could be a significant severe weather event for E Kansas, finally! After last weeks tornado outbreaks and last night's wedgefest I'm not sure things could get any better, but if this model run verifies it could rival some of the bigger Plains setups this year and close to home! We all should keep a CLOSE eye on things.

 

[Derek Weston]

ECMWF has also been showing something big...

 

[Brian Stertz]

Thursday does have strong/violent tornado (High Risk) potential written all over it...especially for NE/EC Kansas, NW/WC Missouri, extreme EC/SE Nebraska, into much of Iowa. This potentially historic type outbreak will be manifested by an unseasonably very strong 850/500mb crossover across the areas mentioned above...strong early June instability...with a strong warm front across the I-80 corridor in Iowa (hint). If things continue to look as good as advertised, I will be taking off for sure Thursday from work. Long tracked tornadoes are certainly possible Thursday.

From a pattern recognition stand point....this would be along the lines of the June 7, 1984 outbreak that slammed much of Iowa...and the night-time Barneveld WI F5.

 

[Brian Stertz]

The 00z GFS looks very ominous for much of Iowa into S.Minnesota. The deep layer shear will be well in excess of 60 kts. with very strong instability at LL. The nose of a very powerful UL jet is also aimed at Iowa. Right now, it would appear that the most significant and dangerous tornado threat will be across N/C Iowa into S.Minnesota...possibly up into the Twin Cities area. This looks potentially like one of those historic type synoptic tornado outbreaks. The scary aspect of this Thursday event is that the LL jet during daylight hours is forecasted to be in the 45-55 kts. range. Couple this with 50-70 kts. at 500mb and Td's in the upper 60's and low 70's & this is the recipe for significant tornado outbreak. Stay tuned...

 

[Mikey Gribble]

There have been notable changes in run to run and model to model, but one thing that has stayed the same is the exceptionally strong kinematics, so I am getting on board with that. The exact location of surface features is a crap shoot ATTM. My biggest concern at this point is having quality moisture in place. Something is wrong with both RAP and COD today, so I will have to wait for tomorow to look into this farther (COD is off 6 hours and RAP has 850 winds veering on Thursday while the GFS on COD has them backed, I have no idea what is going on). As long as we can get at least upper 60 dewpoints in place (and strong CAPE), with the exceptional wind shear this could be a very nasty outbreak. We are more than likely going to be dealing with quick storm motions again too, which sucks bad, but I'll take it.

 

[Mike Smith]

The 12Z Sunday European and GFS make Thursday look dangerous. Both are showing lows with central pressures well below 1000mb (one showing a 989mb -- in June!) in Kansas at 12Z Thursday and 00Z Friday.

250mb winds are still depicted at more than 100 knots across Kansas.

I am not at all worried about moisture given that it is the first week of June, the fact the ground across the eastern half of Kansas is completely saturated, and that more than four inches of rain have fallen the last two weeks across the northern third of Oklahoma.

While it is far too soon to try to get down to details, I believe the period from Wednesday afternoon through Friday is going to be extremely active with a major outbreak likely Thursday.

 

[Brian Stertz]

Agreed Mike...the 12z Euro was catching on to a slightly slower and a bit further south trend with the upper system...and this was seen on the latter periods on the ETA. This would support a more active tornado outbreak for Nebraska, Iowa, and possibly sections of N/C Kansas...and later into W. Missouri. This looks like a classic dual threat of intense tornadic supercells on the warm front and dryline. If the 850mb flow veers as much as hinted, this could bring the most dangerous tornado threat to much of Iowa....still am thinking this may end up similar to the nasty tornado outbreak on 6/7/84. The forecasted 00z sfc low position will be very close to where it was that evening...a 990mb low near Sioux City IA. This is the pattern recognition that I was able to find this closely resembling.

 

[Kenny Drake]

For once my work schedule and a significant severe weather day appear to be working hand-in-hand (I have Thursday off). European models and the NAM have been fairly consistent in a very strong dynamic setup for Thursday which, depending on the yet-to-be-seen details, could stretch from S. MN to S.C. KS. Moisture will not be a problem this time of year. Oklahoma is sitting in the low 70 dewpoints consistently. With such a strongly forced setup there will be no problem advecting this rich gulf moisture northward by Thursday morning. I believe overnight convection (Wednesday into Thursday) will play a significant role in narrowing down the chase target but if I lived anywhere from the Twin Cities southwest to Wichita and eastward towards St. Louis, Chicago, Milwaukee, etc I would be keeping an eye on this system. Due to the strong dynamic forcing, shear will likely be approaching insane levels. Initiation will obviously not be an issue. At this point I'm waiting until Thursday morning to see how bad overnight convection screws things up as we are probably not going to need the added 0-1km SRH from OFB's. I'm thinking mid 60 dwpts to the MN/IA border, 70 degree dwpts in Des Moines and south to northern Missouri. South of there the boundary layer may mix out somewhat (sorry it's June.)

Just for kicks, the Davenport IA sounding looks primed for tornadic supercells, albeit moving very fast. These storms may be moving off to the NE-ENE approaching 60 mph. Right-movers may get somewhat of an ESE component which would increase the SRH even further (increasing shear at all levels given progged wind fields.)

 

[John Hudson]

GFS is breaking out a lot of precip ahead of this system. I am hoping this doesn't result from widespread convection initiating before shear becomes optimal.

Speaking of shear, it looks to take on the most impressive proportions in S MN and just about all IA. I'm still interested in what the hodo for Sioux Falls and areas east might look like, but Earls only goes out to 72 hours.


John

 

[Brandon Sullivan]

I'm still interested in what the hodo for Sioux Falls and areas east might look like, but Earls only goes out to 72 hours.

You can also go to this site http://weather3.admin.niu.edu/machine/

and get soundings out to 84 for WRF and 240 for GFS.

To add to the FCST..

A very nice setup indeed. With a low like that in June it will be worth remembering.. I like the SW IA area right now..

 

[Mikey Gribble]

Well you guys don't have to worry about moisture, but I'm going to. I am well aware of the fact that we'll have upper 60's to low 70's over the warm sector, but both the NAM and GFS have been consistent in showing a wide moisture gradient along the dryline, so storms would have to move quite a ways out over the warm sector to realize the better moisture. Add a strong cap to the scenario (storms firing later in the day) and I have some concerns about storms making it into the better moisture/lower LCL environment before dark. Here is LCL heights from the GFS and it shows ML LCL's over 1800m until you get well out over the warm sector. http://beta.wxcaster.com/models/gfs/central/CENTRAL_GFS_MLLCL_GPH_84HR.gif
The models have been consistently overdoing the cap this year and with quick storm motions I think we will get the storms well off the dryline with daylight to spare, but as of now this is still one of my primary concerns. I do think Thursday will be a good tornado day, so by no means do I think this is a show stopper, but it is still reason for concern IMO and may inhibit the tornado potential.

 

[Rich Thompson]

You should have some moisture concerns. Substantial mixing has been occurring the past couple of days inland from the Gulf Coast. This will likely improve in the next two days, but we'll still have some lingering effects.

It's June and it's getting pretty warm in the warm sector. With post-dryline temps well over 100 F, and pre-dryline temps in the lower 90s, it would be nice to have low-mid 70 Tds. We might scrape up low 70s right along the warm front. I don't think LCL heights will be so high as to kill the tornado threat, but this is one reason (along with the cap) why you don't see as many June warm sector outbreaks (compared to May).

Rich T.

 

[Joe Acord]

GFS 84 ...

12Z data indicates that sfc low is expected slightly south of I40 across western OK at 00z Thursday night. SFC winds are showing se-ly 20 in the OKC metro area during that time. 850 winds from the sw at 50-60 knots. 550MB winds from the west at 80-85 knots. 2500 j/kg CAPE. 65-70 deg DP's.

Anyways, according to the basic data above, I am guessing that Central OK may get the undercard to the main event that everyone is thinking is going to happenng in nw-ern MO and SW-ern Iowa. I am pretty skeptical that things are going to play out that far north.

I want to thank Glenn Rasmussen for catching my typo...