I have been fascinated by severe and tropical weather since the 2004 season. What a season that was!! Also a wave swell freak!
By: Thrawst, 5:55 PM GMT on April 07, 2013
Good afternoon! Welcome to the severe weather analysis of April 7th, 2013 in the Central Plains. This analysis will cover all aspects that will serve to focus severe weather in that particular area. Aspects that will favor, and inhibit initiation of thunderstorms will be covered.
Today's severe weather setup looks like a setup that can be seen many times in the late spring and early summer up in the high plains of the United States. A relatively small, but enhanced, area of severe weather is located in south Central Kansas, and north Central Oklahoma, where very large hail (2"+ diameter) and isolated damaging wind gusts will likely be the main threats. However, an isolated tornado or two will be possible along and near the triple point (Dryline and warm front intersect).
Kinematics today over the central United States are marginal. There is no massive trough that is evident across the Rockies as of yet, but, according to Figure 2, there is a small trough currently (as of 1pm EDT) centered over eastern Colorado and northeastern New Mexico.
(Figure 2.) - The small dips in the black isobars indicate a small trough.
This small trough, and its associated 500mb flow has allowed a 1004 millibar low to form in the panhandle of Texas.
This in turn allows a moisture front (aka, a dryline) to form on the southeast flank of this surface low, as you can see on Figure 3. As a large cap is currently in place over the area, it will take a forcing mechanism to reduce the cap enough so storms can initiate. For today's setup, the forcing mechanism would be the cold air aloft (in the 300-500 mb range), along with persistent Southeasterly winds colliding with southwesterly winds at the surface. As air cannot go around, it must rise, thus condensating, and clouds form into storms.
Thermodynamics however, look far more impressive. With temperatures expected to rise into the mid 70's across Kansas and Oklahoma today, along with dew points expected to rise into the low to mid 60's due to a persistent 20-30 knot Low Level Jet (LLJ), Convective Available Potential Energy (CAPE) values will soar into the 1500-2000 J/KG range. With such a large CAPE value with the cold temperatures aloft will create ripe conditions for very large hail formation, with any storm that does develop throughout the afternoon, and the SPC has taken into consideration these factors and acknowledged a "significant parameter" for large hail in parts of Kansas and Oklahoma.
Based on current models, it seems as if tornado potential is marginal, but non-zero.
This forecast sounding does have a loop signature (which is favorable for tornado formation), but the loop is not large. In order to have a setup which favors more tornadoes, the hodograph must have a large, looping signature, which according to this sounding, does not.
There is a low level jet present, about 20-30 knots, which is sufficient to have a tornado risk. The low level jet, according to its speed, will allow the low level shear to increase, which is where for tornado development is most important.
STILL, as there is some low level shear, and plentiful instability present in the area, any storm that forms in and near the triple point will have the potential to produce an isolated tornado and the SPC has introduced a 5% probability that you will see a tornado within 25 miles of a point.
I will do my TOR:CON values just because I'm bored:
TOR:CON - the chance you will see a tornado within 50 miles of any one location.
South central Kansas: 4/10
North central Oklahoma: 3/10
All other areas in slight risk: 2/10 or lower
Tomorrow's setup looks even more favorable as a very pronounced trough is expected to pivot into the Western United States, allowing more forcing, shear and instability than today's setup. I will write about this setup tomorrow after school!
Have a good day!