Friday Night Severe Potential?

Ok..in looking at the models from the GFS 06Z, I am seeing a couple things of interest.

First, from the upper levels, we are near the rear right quad of a jet streak, this should help with some lift.

Second, we some 500mb vorticity passing just to the north of the metro in the afternoon into evening on Friday.

Third, we have a sagging cold front, albeit weak, trailing from the NE CONUS back down through the central Plains.

This is supported by fronto being shown on the 850 mb level. There is a 850 low progged to be right on top of the surface low in central KS as part of the tail of the trailing cold front.

This should bring the LLJ just through our area ahead of the frontal zone.

The SREF advertises a bit more 500mb strength a bit further to the south through the central region of KS through the metro. This would provide adequate lift via PVA.

Below is the graphic of the CravenBrooks severe composite. Brings this area into direct focus with large values.


Looking at the Supercell Composite, it brings this potential through earlier in the day, lending me to think more of a hail/wind threat from these storms based on timing.

In looking at the Sig_Tor parameter, it also follows the Supercell Composite, but does leave a bit more potential for the metro in this composite.


Based on the soundings, it appears we have the following potential…

Date: 3 day valid 0Z SAT 31 MAY 08Station: KMCI

Precipitable water: 1.37 inches
Sfc-500 mean rel hum: 42.19 %
Est. max temperature: 32.57 C = 90.63 F
Cap Strength: 1.17 C
CAPE (B+): 2556.73 J/kg
Max Up Vert Vel: 71.51 m/s
Conv Inhibition (B-): 30.96 J/kg
Storm rel helicity (0-3000m) 127.8 m^2/s^2

Dewpoints are progged to be in the mid to upper 60s. So, based on the sounding info, I would deduce that we would have a hot and humid day, with a weakly capped environment with good instability.

The problem for tornadic development would be the SRH being 127. While it is a fair value, I would want to see it a bit higher. Sheer is adequate, but largely unidirectional.

Here is what the NWS has to say in their discussion… “A GOOD AMOUNT OF INSTABILITY AND SUFFICIENTSHEAR COULD ALLOW FOR SEVERE STORM POTENTIAL IN THE FORM OF LARGEHAIL AND DAMAGING WINDS FRIDAY AFTERNOON AND EVENING.”

I am thinking that as cells do form south of the boundary earlier in the day, these have a better chance of being supercells. Not excluding that from this area, as the day goes on into the evening, chances greatly reduce from tornadic threat to more of a linear storm structure with hail and wind being the main threat.

Lets watch so more runs, but this is my take on this upcoming event.