11/12/05 NOW Central Plains

Sitting in St. Joseph MO, with Darin Brunin, gonna take a quick glance at the MCD. Seeing turkeys to our west, southwest. If anyone can nowcast, please pm me. Looks like initiation is nearing and embedded tornadic sups are likely.
 
A new cell is now just showed up on radar right over the MO river it will be raceing through Mills county towards E Pottawatamie county in Iowa
Red Box now issued
 
Continued low-level mixing -- with an agitated zone of cu noted in vis imagery ahead of dryline currently mixing east -- indicates CINH is dramatically weakening. Increasing boundary layer moistening/heating and very steep mid-level lapse rates is supporting sbCAPEs A0A 1000J/KG across eastern NE south into eastern KS -- with increasing convergance along developing dryline. Any activity that ingests boundary layer parcels will have the potential to quickly become violent with very large hail... Given strong low-level instability and 0-6km vertical shear in excess of 50-70kts. Low-level shear will also support tornadoes... With 100-200m2/s2 0-1km SRH currently widespread across the region.

I still see the best potential to the south of I-80 in southwestern IA -- primarily near Nebraska City.
 
Dont forget though that we are probably talking mini supercells today... so very large hail is probably not going to happen but severe hail is definitely likely.

I dont think I could necessarily call the instability strong, but for mini supercells I suppose it is decent. This is definitely a situation where the normal severe weather / tornado rules dont apply.

Our cold-core low has since been reabsorbed into the flow according to the 500mb analysis on SPC mesoanalysis page, however the trough remains cold-core so it will be interesting to see if this follows the theory of Jon Davies.
 
The severe warned cell over Shelby County, IA has a quoted speed of 60 mph to the north in the warning text. :shock: Best of luck to anyone out there trying to chase that.

Skip
 
The warning just issued for Cass County has a quoted speed of 75 mph! Wow! Its more of a one shot opprotunity at a storm intercept rather than a storm chase at this point.
 
Dont forget though that we are probably talking mini supercells today... so very large hail is probably not going to happen but severe hail is definitely likely.

I dont think I could necessarily call the instability strong, but for mini supercells I suppose it is decent. This is definitely a situation where the normal severe weather / tornado rules dont apply.

Our cold-core low has since been reabsorbed into the flow according to the 500mb analysis on SPC mesoanalysis page, however the trough remains cold-core so it will be interesting to see if this follows the theory of Jon Davies.

I don't think I'd compare this to the type of environment that Davies talks about in terms of cold-core tornadoes. This activity will still be warm sector activity, more like a classic severe weather situation. The "cold core" setups that Davies has written of is more from cool-sector activity located under a cold-core upper-low, more like what we saw a few times this spring in Kansas and nearby areas.

As others have noted, low-level shear is strong, though not a whole lot of curvature in the hodograph owing to SSW surface flow across most the warm sector ahead of the dryline. Surface flow is a little more backed to the SE across nw IA and into southern MN, but the upper-level flow is more backed up there as well. The deep-layer shear vector is more parallel to the dryline than it is normal to it, with the relatively backed upper-level flow promoting downstream seeding, particularly where the upperlevel flow is SSW across the north end of the target area.

Since I'm in Norman, I'd head up to the northeastern OK / se KS area if I were chasing, where upperlevel flow is more westerly or southwesterly. In addition, decent insolation has been occurring there over the past several hours, allowing surface temperatures to rise and CAPE to increase. However, surface winds have veered to the SSW, which is lowering SRH in the area. Strong wind fields above the surface is still yielding 40-50kt deeplayer shear and moderate SRH, and the upper-level jet streak is located such that the ne OK and se KS area is located in the right-entrance region, yielding upper-level divergence, which, along with DPVA aloft and surface heating, is weakening the cap. Nice cu field extending from near Kansas City to Ponca City to Ardmore.

Storm motions should be pretty fast today owing to strong flow at all levels. Good luck to anyone out!
 
I don't think I'd compare this to the type of environment that Davies talks about in terms of cold-core tornadoes. This activity will still be warm sector activity, more like a classic severe weather situation. The "cold core" setups that Davies has written of is more from cool-sector activity located under a cold-core upper-low, more like what we saw a few times this spring in Kansas and nearby areas.
Stuff going on north of the low would not really be warm sector storms. I was talking about the situation in general and probably should have been more clear. I was thinking that it would be interesting to see if no storms formed in the warm sector but tornadoes formed N and NE of the low as Jon Davies talks about.
 
Sitting in STJ with Dick and Darren ... nice clearing around CU field here that has hardened up nicely, but towers continue to topple for now. Hoping things will be changing in that regard soon. Cells have attempted to fire both north and south of STJ, but we will need a good, strong updraft to push through. Hoping to see something like what is happening in Shelby Co. down here, but these really are booking today, so who knows - will be tough to keep up.
 
Stuff going on north of the low would not really be warm sector storms. I was talking about the situation in general and probably should have been more clear. I was thinking that it would be interesting to see if no storms formed in the warm sector but tornadoes formed N and NE of the low as Jon Davies talks about.

I'd say the warm sector goes all the way into southern Minnesota. Sure, the "warm sector" up there isn't too warm, but I'd put the main warm front from Souix Falls to the Twin Cities, with maybe another warm front from souix City to Davenport (across central Iowa), as can be seen in the change in dewpoints and winds.

For anyone using the latest beta version GRLevel3, you can go ahead and use my scripts today if you want. Go to GIS >> Manage Placefile >> Add >> {enter the script address for what you want}

For METARS: http://www.tornadocentral.com/grlevel3/met...rs.php?state=** where ** is the two-letter state code (IA, KS, MO, etc).

For OK Mesonet: http://www.tornadocentral.com/grlevel3/OKmesonet.php

For SPC convective outlooks: http://www.tornadocentral.com/grlevel3/swody1.php

For SPC probability graphics: http://www.tornadocentral.com/grlevel3/swo....php?type=***** where ***** is tornado, wind, or hail.

For SPC watches: http://www.tornadocentral.com/grlevel3/validww.php

The METAR script is still a little buggy, so don't get made at me if something doesn't display correctly (and it doesn't display <32F dewpoints or temps yet)! The OK Mesonet script doesn't do SLP either :lol:

EDIT: I don't want to step on Tyler's pay service, so I'll probably take the scripts down at the end of the chase day. :lol:
 
...and???

Interesting to see that even in VCP12 the TVS icons are WELL behind reflectivity by the next update... I wonder if they are moving too fast to have any sort of sustained tornado (if one at all) on the ground.
 
I still see the best potential to the south of I-80 in southwestern IA -- primarily near Nebraska City.

I definitely would have been taking off after those cells that fired just to the northeast of Nebraska City (and to the east of OMA) earlier -- which are currently TOR-warned to the west of DMX. Prime environment for tornadogenesis with 200-300m2/s2 0-1km SRH significant vertical shear -- with some marginal sfc-based instability...

NOTE: Please try to keep posts informal and remember that repasting NOAA products is a TOS violation...
 
Jim Bishop is currently on the tornado warned cell in Guthrie County, Iowa. But he lost cell coverage, so can't confirm a tornado at this time.

Simon
 
A couple of nice supercells west of DMX/DSM right now, moving quickly to the NE. Very high shear and decent LCLs, in combination with the current supercell mode, would suggest a tornado threat with these storms at they past just nw of Des Moines. I'm a little surprised to see the high (>65 dBz) reflectivities with these storms given the marginal instability in the area. Latest RUC analysis/SPC mesoanalysis indicates SBCAPEs in the <500 range in this area, with significant CIN for a surface-based parcel. I can't imagine these storms are elevated, so I don't have much confidence in the RUC mesoanalysis solution right now.

Rdale, aren't the algorithm-based features (meso, TVS, etc) based on the previous scan? I mean, by the time the new TVS/meso/hail alogrithms are out, there is already a new radar scan (esp in VCP 12)... With the fast forward motion, this means the TVS indicators are significantly behind the radar signature most of the time. I'm not sure about this, however.
 
"Rdale, aren't the algorithm-based features (meso, TVS, etc) based on the previous scan? "

Yes, but usually when in VCP12 the 4-min updates the icons aren't that far behind with "normal" storms, these speedsters are humming so fast there isn't even any precip where the icons are showing rotation!
 
I think there is some excellent potential for tornadoes through the next couple of hours... Nice backing southeast flow ahead of the boundary (and southeast of the surface low), with significant vertical shear in excess of 60knts across the area. Current mesoanalysis showing 500-1000 mlCAPE in the area, with strong low-level shear (200-300m2/s2 0-1km SRH). >60kt 0-6km deep-layer shear per mesoanalysis will help for strong and sustained supercells. The current TOR-warned storms to the west of Ames and DMX looks georgous... With some awesome low-level rotation on both! Too bad for work, otherwise I would have been in IA today...
 
Incredible gate-to-gate shear just north of Linden with the southern-most supercell to the west of Des Moines... Cyclonic meso has tightened up very rapidly within the past few scans. The storm to the north is also showing a nice couplet -- with reflectivties pretty high (>65) with VIL pretty up there as well (>55) indicating potential for some pretty large hail along with the tornado and wind threat.
 
Well sittin here in Ft. Smith, twidlin my thumbs, among other things....
Seems the cap is a wee bit too strong down here. Now im wondering if anything at all is going to fire. So its the ole sit and wait game.

And Nick, dont get your panties in a wad, 8) be happy.
 
I thought I'd share this bit of trivia...
The Iowa State -vs-Colorado game takes place in Ames a little later today.
Lots of tailgating going on right now. :shock: The media is trying to warn everyone about the approaching storm.

Confirmed tornado touchdown being reported close to the Dallas county / Boone county line - approaching Madrid. It hit Woodward - damage being reported. "Cars flipped, houses leveled, trees down." EMS is going door to door.
 
And Nick, dont get your panties in a wad, 8) be happy.

LOL... :lol:

Both storms continue to show strong low-level mesocyclones... With +92knt gate-to-gate shear right over Stratford, at the moment (with a likely intense hail core as well). The storm further to the south also shows a pretty tight mesocyclone just to the west of Luther. I wouldn't be surprised if these storms had tornadoes on the ground again right now...
 
I'm suprised these storms are able to maintain their intensity given the marginal instability. Very strong low-level mesocyclones evident on DMX radar, one in Hamilton and another in Boone county. Ames may dodge the tornadic part of this storm by a few miles, as the meso may move a few miles north of Ames. Man, those are nice couplets! Tornado reported recently in Stratford, in Hamilton county.
 
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