6/20/06 NOW: MN / IA / WI / NE / CO / KS

Sitting in Ames IA. Trying to stick along the warm front at the moment New MD for the Northern Iowa and southern MN area. Watch may be issued if convection can organize. So Just watching trends. The CU out to the west doesnt look like much of a Cu field kinda thined out and moved away from Soiux City. Convection initiating along the IA and MN border. Not to far from it but being patient.

Good Luck to any one out
 
Wow! That cap is still insanely strong. It seems the strong heating required to break it did not occur. And I thought that cap would go easily this afternoon, boy was I wrong. This looks to be an entirely nocturnal MCS event, perhaps elevated. This sucks too, because LCL's are in the 800-1200m range. Mesoanalysis does show a hole in the CINH over west central IA. The cap looks to be killing those showers in southern MN though. But those showers may be all that's needed to weaken the cap further. It sure is getting late however. Happy hunting!
 
I keep going over the meso analysis page and it seems all the parameters are in place for something aweful to happen around nw IA, sw MN right now, also CINH has dramatically dissapated over nw IA. What am I missing that could explain why nothing is happening there?

EDIT: Sorry, I started writing this post while David was posting his reply, in case you're wondering. But I'm a little confused, how could CINH be gone with a strong cap in place, could someone help me out here?
 
I keep going over the meso analysis page and it seems all the parameters are in place for something aweful to happen around nw IA, sw MN right now, also CINH has dramatically dissapated over nw IA. What am I missing that could explain why nothing is happening there?

EDIT: Sorry, I started writing this post while David was posting his reply, in case you're wondering. But I'm a little confused, how could CINH be gone with a strong cap in place, could someone help me out here?
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Sean,

David was referring to the area of weakened CINH (per SPC mesoanalysis) across western IA (as you mentioned yourself). There is still an inversion layer (weakened in some spots) across much of the warm sector, nonetheless, mesoanalysis has shown a weakening trend in CINH the past couple of hours; mainly across western IA (and sw/sc MN) due to surface diabatic heating. However, CINH has yet to erode enough to allow for parcels to reach their LFCs (as indicated by those weak thunderstorms in southern MN earlier which were ripped apart and got their inflow 'chocked' off by the capping, since air was too negatively buoyant to be brought to its LFC).
 
If CINH is gone, there is no cap. The 0z OAX sounding shows that the cap is pretty weak, and likely nearly nonexistant in areas where the dewpoints are >70F (in other words, in western IA). The wind profile looks very favorable for supercells, and the degree of low-level shear (adjust the 800-700mb winds up 5-15kts given stronger LLJ to the east of OAX) and moderate LCL heights (in IA, where Tds are >70F again) still suggest a threat of a strong tornado or two for any supercell in the threat area the next few hours. I think the 59kts 0-6km shear on the OAX is greater than the 0z RUC mesonalysis too. Regardless, I'm a little surprised we're not at least seeing a decent cu field based on that 0z OAX sounding. Again, the thermo profile looks nice in western IA if you adjust the 0z OAX sounding for low-70 dewpoints. The kinematic profile looks very favorable for supercells and tornadic supercells, though the threat is entirely conditional (and meeting the condition -- initiation -- is looking less likely with time).
 
The LI values in western IA are very low, right where that weakened CINH is. SBCAPE is also at 4000 J/kg. Double digit supercell composites are rampant. What is preventing development there? Is it lack of forcing, decrease in heating due to the onset of nighttime, or something else? I do see high clouds on the satellite imagery. The 1 km EHI's are as high as 4! If something goes, it could be big one.
 
RUC model initializations are showing minor ridging at 700 and 500 mb levels. Isn't it possible that such a weak ridging pattern at upper levels, though discrete, could lead to subsidence through the lower layers as well? It would surely answer the dissipation of the Cu field.

Just a thought.
 
Hearing some slow rumbly thunder here in NW IL beneath the weak elevated convection.

Visible satellite in the waning light of day still shows absolutely no cumulus in the western half of IA. Like mentioned above I'm very surprised, especially with the amount of LL moisture and the leftover boundaries from earlier today.
 
RUC model initializations are showing minor ridging at 700 and 500 mb levels. Isn't it possible that such a weak ridging pattern at upper levels, though discrete, could lead to subsidence through the lower layers as well? It would surely answer the dissipation of the Cu field.

Just a thought.
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The 21z RUC run showed a compact vort max located in southern IA, moving into IL. DNVA would be occurring on the back side of this departing vort max, which means that western IA would be seeing large-scale subsidence in its wake. This vort max is a seperate feature from the strong vort max that came through IA earlier this morning and helped induce the widespread convection earlier.
 
TAMDAR soundings showing a significant inversion around 875-825mb across southern MN / western WI (nothing out of Iowa lately.)
 
Yes very much in agreement Benjamin and Jeff..there was a large degree of subsidence behind that morning wave with 700mb temps rising and very little 500mb cooling. The 12 degree 700mb temps on the SPC Mesoanalysis indicate that the nasty subsidence has shifted eastward almost to the Mississippi River. Some slight mid-level cooling was sagging into N.Nebraska and SE South Dakota. Today is one of those "what if" setups that seems to have plagued this chase season. I certainly would have expected some monster supercells just basing off my earlier peeks at the boundaries, EHI, supercell composites, and Craven indices.
 
Wow, I am just continually confused about what is going on. Assuming the cap broke/weakened dramatically within the last 2 hours, why would convection, or precip not occur? GFS/NAM has been breaking out precip in this area for days (2), and now this? I am sitting at a rest stop near Ames, IA with Kurt Hulst, Fabian Guerra, and Skip Talbot....and we see a wierd belt of altocumulus, that is in wake with a 500 mb impulse...but nothing in signs of convection...and twilight, is nearing...
 
Quite a few warnings/spotter reports out of NE CO today. Hope there's some folks out there
now who can post some reports: the tornado-warned cell near Yuma has some pretty impressive
low-angle velocity signatures!
 
Stan Rose Wrote:
Quite a few warnings/spotter reports out of NE CO today. Hope there's some folks out there
now who can post some reports: the tornado-warned cell near Yuma has some pretty impressive
low-angle velocity signatures![/b]

Looks like the event was much farther west today. I was suprised that IA didnt not see a single severe storm today. I was waiting for a good show over IA today and look what happend. :angry: Still a chance tonight something could pop up but it appears that anything in the way of severe storms is low. SPC still has a 30% chance of hail and a 5% chance of tornadoes for Iowa.

Many Tornado reports farther west today and in a 2% chance area by the SPC. (Now a 5% chance) TOR warned storm in western kansas right now. There is reports of a tornado with this storm. Blakeman and Atwood are in the path of this tornado.

IN ADDITION TO THE TORNADO...THIS STORM IS CAPABLE OF PRODUCING
BASEBALL SIZE HAIL AND DESTRUCTIVE STRAIGHT LINE WINDS.

-MatthewCarman.
 
a storm west of seldon kansas is moving east at 50 mph and is capable of producing TENNIS BALL SIZED HAIL and 60+ winds. Yikes! Hail that large can do lots of damage. The storm appears to be a supercell. Storms are on the increase and the whole thing is moving east from Kansas/Nebraska Towards The Iowa/Missouri area. New SVR thunderstorm watch issused for parts of Nebraska and Iowa. Still a chance we could see a tornado or 2 tonight so lets not call this event a bust yet. Especialy when storms out west our capable of producing destructive winds 70+ mph and destructive tennisball sized hail and conditions are still very favorable for SVR storms. Atmosphere is still very or extremely unstable so looks like a nighttime event now. Anybody still chasing? -MatthewCarman.
 
I think you read the LSR wrong - 60mph winds were estimated by a spotter with dime-sized hail. No tennis balls have been reported, and AE reporting a max estimated hail size of about 1.5"
 
I think you read the LSR wrong - 60mph winds were estimated by a spotter with dime-sized hail. No tennis balls have been reported, and AE reporting a max estimated hail size of about 1.5"
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NOAA said the storm west of seldon was capable or producing tennisball size hail. "DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING TENNIS BALL SIZE HAIL"

Sorry for the mistake I forgot to put the word capable in. New TOR warning in Kansas looks like the tornado threat is not over yet.
Decatur county in Kansas is now TOR warned.
 
Gotcha. It looked like things flared up a bit (AE even up to 3.5" briefly) but have now diminished, but it's also getting far from the radar. Only hail report was 1" so no tennis balls.

I think the TOR was more of a CYA, rotation didn't really look that strong but again it's far from the radar. It was canceled early - what do you see to keep the tornado threat significant overnight?
 
Still a chance we could see a tornado or 2 tonight so lets not call this event a bust yet. [/b]

The heating today barely removed the cap...just briefly perhaps. With the sun having set long ago now and still very warm 700mb temps I'd say we are safe from tornadoes tonight.....hell the rest of 2006 at this rate.
 
Ironically, now WI is coming to life, after midnight. Clark County has a fairly nice storm that has been hovering just below 100% POH and VIL around 35 with VILD between 3.5 and 4.0. Could be better but it looks alright. Stuff over Lake Michigan really flared up. And if you look now on the KARX loops you can see a lot of light echoes popping over SW/WC WI. Maybe I will be surprised. Now I have something to watch while I wait for the SWODY1. :D
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Same thing going on down along the Illinois/Iowa border. Little cells have been trying to develop for the last few hours in that area but are still struggling just as things did all afternoon. Airmass is still primed and shear is still ample over central Illinois should anything decide it finally wants to go up.
 
Just got back from a clear sky Iowa bust and to top it off a 120 mile ride in a tow truck after Jordan's fuel pump went out from what I can tell. The 2006 funnnnnnnnn continues :p
 
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