Moisture/Dry Line Retreat

Dryline/airmass retreat in western KS/OK/TX. Benjamin

 Channel Difference

Pre-Storm Analysis Across FGF Area

During pre-storm analysis over the FGF CWA, I looked at baseline derived products from GOES-16 in a 4 panel as shown below, which included the moisture difference product. 

There is a tongue of slightly higher CAPE values, approximately 500 J/KG, entering the western portion of the CWA. This coincides with a tongue of higher TPW, around 1.2 inches and better LI values (-3 to -5). The better moisture can also be seen in the moisture difference panel on the better right.

I also looked at a 4-panel water vapor procedure, which included the upper, mid, low, and simple water vapor RGB. This was mainly to get a feel for the larger scale moisture and flow pattern. Once some instruction on the RGB was given, I found it useful in assessing where the moisture contributions were coming from.

A look at radar data from both KMVX and KMBX reveals a fine line or surface boundary approaching the FGF CWA from the west. This line is the leading edge of the drier air, which means the focus for convection is generally going to be along and east of this boundary. The CAPE and TPW gradients were generally along and east of this line as well above in the derived products.

I also looked at a modified MetOps sounding in the western part of the CWA. The modified sounding had CAPE values around 700 J/kg.  Before modifying the sounding, there was little to no CAPE. These values were generally consistent with the baseline derived, although slightly higher.

-Ironman

4-Panel Baseline Derived Products

A useful 4-panel for mesoscale analysis using Baseline Derived Products is to have TPW, CAPE, and LI with the Moisture Difference product. This gave me a quick look at the changing environment with increasing moisture and instability. The moisture difference product adds value due to its higher resolution. Once the product was explained in more details, it makes sense why areas with thicker cloud appear darker. This could be confusing at first glance since drier areas are darker.

-Ironman