AllSkyLAP Layer CAPE, GOES Cloud Top Phase, AllSkyLAP Layer Pacel LI, Day Cloud Phase Distinction 4-panel

Here's another interesting 4-panel showing AllSkyLAP Layer CAPE (top left), GOES Cloud Top Phase (top right), AllSkyLAP Layer Parcel LI (bottom left) and Day Cloud Phase Distinction (bottom right) at 1700Z.

Much like yesterday, the Layer CAPE product showed higher CAPE areas fairly well (except where there are thicker clouds, such as in NE SD where there are thunderstorms, so the GFS is used as the background). It even picked up on some lower CAPE areas, such as the one over W ND, which SPC's Hourly Mesoscale Analysis also showed. But, also like we've seem through the experiment, the AllSkyLAP Layer CAPE values are lower than SPC's, in some locations by as much as 500-750 j/kg. The AllSkyLap Parcel LI also showed lower values (by 1 degree or so on the average) than were displayed on SPC's MULI product, but the areas compared favorably, except where there were clouds.

A comparison of the Cloud Top Phase and Day Cloud Phase Distinction products also yields some interesting results. The Cloud Top Phase product is doing a pretty good job distinguishing ice, mixed and water phases, particularly where convection is firing in northern UT, S WY and N CO. The coverage of "ice" cloud tops does seen a bit overdone where there are cirrus clouds, especially in MT, W ND/SD, and E ND/SD stretching E into MN. It also is overdone where there don't appear to be too many high clouds (northern MN). The Cloud Top Phase product also seems to be having a hard time where there are both low (water) and high (ice) cloud tops visible in the same region, such as central ND and central MT.

- Thomas Bell