May 22, 2011

May 22: ne Oklahoma or north Texas? It's ne Oklahoma!

We are sitting in Perry OK with a Noon checkout....and are debating two targets....our original one near SPS and east (where both the NAM and the latest RUC forecast large values of CAPE) and the area of ne OK, where the RUC (but not the NAM forecasts nuclear bomb CAPE of 7000 J/kg). 

Next looking at the forecast soundings....the NAM has CIN for ne Oklahoma and very little CIN for the southern target...and the RUC has CIN holes in both locations. Looking at the forecast hodographs there would be no contest. ne Oklahoma has dramatic loops with nearly 30 knots of low level shear in both the NAM and RUC forecasts. Looking at those hodographs, I see the shear vectors nearly at right angles for 0-0.5 to 0.5 to 1.0 km!!!! There are dramatic turning of the shear vectors in the hodographs for the southern target too....but the deep layer shear is 36 knots (0-6 km) for the southern target and 46 knots for the northern target.

By the way, the hodograph was the key to understanding some of what happened in ne KS yesterday. I am trying to get myself from just assuming that surface winds need to be southeasterly....they don't, because the hodograph is the key. A sw surface wind (wiht adequate CAPE) can give a wind profile favorable for rotating storms if all the winds are shifted to the right on the hodograph. Then the low level shear becomes some found out and pointed out by action yesterday, outflow boundaries can augment the anemic low level shear profiles in some cases....clearly that's what happened in ne KS yesterday. Too bad I couldn't put my own actions behind those nice sounding words....!

Anyway, we have an hour or so before checkout, but our provisional target is very close by....Tulsa and northeast.  The last plot at right shows the position of the cold front and dryline this morning and projected for this afternoon.   

The white arrow shows the jet stream's position this projected for this afternoon, and the red arrow represents the axis of the tongue of high dew points and CAPE for this afternoon.   The green shading shows dew point contour channels starting with 60F, then 65 and 70F.  The semi-transparent cold front and dryline indicates the forecast position of the dryline and cold front this afternoon.   It's been a while since we've chased a very very high CAPE pattern that also has favorable shear.

By the way, our runs in Perry today were absolutely miserable.  :-)  The hotel is about 1.6 miles in a straight line down a multi lane street with no shoulder or sidewalk from the town of Perry.   We ran that way because there was a park there that seemed a good destination.   We forgot to factor in the howling winds which aided us on the outbound, but were in your face on the inbound portion, which was slightly uphill.  Combine that with the inboud being slightly uphill transformed what should have been a pleasant jog into a real chore.   I truncated my run at 4 mlles, but Thom managed 7 miles....and it wasn't fun.  On the other hand, it's nice to keep up the routine of working out each morning somehow.  Tomorrow, if possible, I'll find a gym.