Monday, November 7, 2011

Now: storms

Well, it appears I was a touch too far south with my forecast. But here's a screen capture of the RADAR as the storms happen right now. Wow.

Sunday, November 6, 2011

November severe weather setup

Down south storms can happen almost any month out of the year.

Including November.

Tomorrow looks to be a really good setup for severe weather in north-central Texas. So let's go through the checklist in our ingredients-based forecast.

Surface dews look to be over 60 in the region and even over 65. Easily plentiful for this time of year. And to boot, it's not a wishcast of the model--the dews over 60 are already in place. 850 moisture looks good, too.

MLCAPE is progged to be in excess of 1500 J/kg. Lots. No CIN.

The model indicates good convergence along the fronts, but in the warm sector not much is shown. This could be a limiting factor. However, we can infer strong synoptic-scale lift from the cooling and strong winds at 500 mb.

Tons, both at low levels and at high. Winds at 850 mb should be in the 30 to 40 knot range, and at 500 mb, around 50 to 60 knots. Veering looks to be pretty good, so the deep shear values will easily support supercells and low-level shear will support low-level rotation.

So what do I think will happen?

Notice the time in all the maps above: 18Z. Included in that is the cap strength, which is nil by 18Z. That's noon, CST. However, with subtle warming going on at 700 mb, storms may be slightly capped. On the other hand, strong winds and cooling at 500 mb indicate likely strong lift. Therefore, I expect there to be storms ongoing late in the morning and, as long as the warm sector remains at least partly sunny, they should intensify through the afternoon. Looking at the forecast soundings below, the low-level jet is forecast to intensify through the afternoon, lengthening hodographs and increasing low-level shear. So the ongoing storms will become more and more likely to rotate at low levels. Provided one storm can stay discrete, tornadoes look to be likely, along with big hail and strong winds.

My target area is between Seymour, TX and Wichita Falls, TX. Prime time will be about 3 PM. Sunset is about 5:30 PM this time of year, so the viewing time will be much shorter than at other times of year. Storm motion won't even be too crazy--20 to 25 knots.

If I were out in that part of the world, I would definitely try to catch a November tornado.


Storm motion:

18Z prog sounding:

21Z prog sounding and hodograph: