Wednesday, April 29, 2009

Zonal, with hidden treasures.

A zonal flow pattern will likely be in swing for the next 1-2 weeks over the central US. While a west coast troughing pattern tends to be preferred, zonal is sure a lot better than ridging. It will not be the most active start to May, but there will be chase opportunities scattered around the central part of the country. Looking at the long term models seems to be pointless anymore, but just this morning the GFS throws a tornado outbreak over Illinois and Missouri at 156 hours out, for next Tuesday. This isn't likely to pan out as it appears now, but does show that there are signs of these little shortwaves embedded in the broader zonal flow. These will be the hope to watch for over the next 2 weeks before we see another shift towards a larger troughing pattern.

The overall pattern might not look particularly favorable at brief glance, but I'd look for several good chasing ops through the first week of May, primarily over the southern plains of Texas and Oklahoma. Early to mid-May I'd look for a noticeable ramp up of severe weather events with a more progressive pattern and a northeastward shift in threat area from the current southern plains location to an area between Interstates 70 and 80 from Kansas and Nebraska into Iowa and Illinois. The middle part of May could be especially active in this region.


Unknown said...

I'm confused. Are you talking about the Linn county tornado being 21 miles?

Andrew Pritchard said...

Yeah... from DVN:

" It was determined that the damage was caused most likely by a single tornado moved along a nearly continuous path 22 miles long through northern Linn County and southern Delaware County. The damage path extended from roughly 2 miles west of Alburnett, or 10 miles north of Cedar Rapids, to about 5 miles west of Hopington, or 10 miles southeast of Manchester. Damage was rated as EF1* along most of the damage path."