17 & 19Z SNPP NUCAPS Passes

Main Points:

1. Temporal Coverage
2. Experimental Sounding adjustments
3. Visualization of Data
4. Comparing Data sources


1. Temporal Coverage
Our CWA (LOT) benefited from two overlapping passes at 17z and 19z. Looked at soundings ahead of the convection to anticipate if any additional convection is expected across our southern CWA.

*I find this product becomes much for useful when we get multiple passes in the day. Ideally, get an hourly pass in the same location would be of much greater use when trying to monitor the evolution of the convective environment. In this case, the environment was not changing much, but is knowing this is still valuable information.

           17z pass                                             19z pass

2. Experimental and Operation Sounding Comparisons:

Operational

Experimental

Took a sounding point ahead of the convection in Kankakee County (LOT). Both showed the relatively dry and low CAPE environment that was expected but think the experimental profile may show a tad too much instability by assuming a perfectly mixed layer. Seems the moisture profile should meet up with the top of the temperature mixed layer which would result in lower CAPE as a result. No way to verify this though, just my thoughts.

Inspecting both the operational and experimental profiles helped confirm analysis seen from GOES-16 derived instability fields (CAPE, LI, etc).
That is:

• We continued to see a low instability and dry low-level environment across our southern CWA. This dry low-level was the main threat as we did observe many outflows running away from convection along with an observed wind gust of 67mph.
• This dry and low instability environment resulted in the expectation that no further deep convection was anticipated as the convective line traversed south.

3. Visualization of Data 
 I found visualizing data is much easier when displayed in a similar fashion to the GOES-16 plan view of derived stability indicies. Explored the available gridded NUCAPS fields (where available) and also provided increased confidence in the environment. Also showed the expected gradient in instability from north to south. The gridded display in NUCAPS could use work, the edges can be quite jagged and coarse looking. Also, had to compare MSAS dewpoints in F while the dewpoint depression in the gridded product was in Celsisus (image below).

4. Comparing Data sources
*One very valuable tool in NUCAPS its high vertical resolution. I was able to select a pressure level of interest to see, in this case, dewpoint depressions across the southern CWA. When compared to surfaces obs & MSAS analysis the gridded 925mb NUCAPS data, I found the same pattern of large dewpoint depressions to the south. This also reinforced my concern for continued outflow winds due to dry sub-cloud layer.

Forecaster: Tahoe