Update on Severity of Sat. Outbreak

Several blog readers have written in wanting an update on the severity of Saturday's severe weather outbreak, after my blog entry yesterday. If you believe the NAM's CAPE forecast, Saturday's will be much worse than today's. Check out these graphics (from our Pro site).

NAM MODEL: MAX CAPE TODAY

NAM MODEL: MAX CAPE SATURDAY

Even looking at other severe weather indices from the NAM, several indicate things will be worse Saturday, and none better. Here's the roundup of severe weather indices, looking at NAM maps this morning (12Z run). The first number is the maximum contoured number from today's forecast, the second is from Saturday's forecast. The number in parentheses is the number that you want to see for extreme severe weather (taken from the lists on my handy-dandy severe weather index page).

CAPE: 2000 / 3500 (>3500)
Lifted Index: -6 / Wide Area of -8 (<-6)
K Index: 30/30 (>40)
Thompson: 40/40 (>40)
Total Totals: Tiny Area of 60 / Decent Area of 60 (>56)
Cross Totals: 25/25 (>26)
Vertical Totals: 32 / Wide Area of 32 (>30)
SWEAT Index: 450/450 (>800)
Storm-Relative Helicity: Tiny Area of 600 / Decent Area of 600 (>450)
Energy Helicity: 3.5/4.0 (>4.0)

So you can see that no index says Saturday's event will be less severe, and the difference in CAPE and Lifted Index ("classic" indicators of severe weather) is significant.

The GFS is similar on a lower scale, calling today's event a 500 CAPE while Saturday's will be 1500.

But of course, severe weather is hard to predict and any minor change in the atmosphere between now and then could mean the difference between a super-outbreak and some showers.