Questions about 4/22/10 outflow boundary placement

[Rob H]

I know a lot of people made the conscious decision to play the ofb/dryline intersection in the higher CAPE environment on 4/22/10. I'm looking back at that event and I still can't pick out the ofb that would make me say "Amarillo is the play". There was an MCS moving through the panhandle to the SE on 4/21, and on the morning of 4/22 there was an MCS moving through the panhandle to the NE.

18z surface conditions:

18z visible satellite:

1. I can see a wind shift somewhere in the sfc condition gap in the E panhandle, but what on vis sat would tip you off?

2. What are the important features to note on the vis sat image? Which are from the 4/21 convection, and which are from the 4/22 morning convection? Which ofbs were more important this day?

 

[JF Massicotte]

First guess on the surface chart about any OFB. Here CES and CDS both show 65/61 with stations just to the west showing 69/63. This is some hint that there probably is at least a differential heating boundary there. Even more important is the strong convergence in central panhandle. No matter where the OFBs are, this convergence screams the area near and South of AMA as initiation zone.

Now on the sat, there seems to be a subtle boundary oriented NNW/SSE in central panhandle, looking at vis loop on SPC Events page it became more evident half an hour later when cloud cover decreased. Looping the image can help a lot to find a boundary that almost stays stationnary and seems to offer resistance the the general flow..

 

[Bob Hartig]

I see what appear to be possibly two boundaries crisscrossing each other there in the panhandle. Whatever the case, it's hard to ignore the bubbling Cu's. Looking at the surface obs, what strikes me about Amarillo is the apparent speed convergence in that area, or just to the north. It's a likely place for localized forcing.

 

[Paul Knightley]

Do you have any lowest scan base radar reflectivity imagery for this event? You can sometimes see boundaries nicely marked on such imagery.

 

[Rob H]

Here's an L2 scan from 19Z:

I'm assuming the ofbs that helped the tornadic storms are the faint lines crossing just east of AMA? Is that two ofbs, or something else?

 

[Dan Robinson]

Looping the sat and radar images usually reveals the boundaries more clearly. Sometimes you can pick them out on the single image, but looping usually is their giveaway.

 

[Rob H]

Looping the sat and radar images usually reveals the boundaries more clearly. Sometimes you can pick them out on the single image, but looping usually is their giveaway.

Thanks, Dan. Satellite loops didn't do much good on this day, but the L2 reflectivity loop really showed the N/S boundary that the cells eventually went up on.