Category: SPG2026

April 27th Severe Storms – A Satellite Analysis

Posted in OCTANE Speed Sandwich, SPG2026, Synthetic GXI on by Kevin Thiel.

A large-scale, multi-state severe weather event is unfolding across the Midwest and Ohio River Valley, extending down into the Mid-South region. With a broad warm sector and CIN dwindling, the first focus was to watch for any discrete cells out ahead of the front that would pose an all-hazards risk. To get an idea of where the best moisture is and where any gradients between dry/moist air exist, I utilized the 4-panel that shows modeled GeoXO data vs GOES-19 imagery. This imagery did a great job highlighting the areas of best moisture and showed a clear distinction in dry vs moist air.

Figure 1: 4-panel layout comparing GeoXO Synthetic data (top) vs GOES-19 obs (bottom)

For monitoring potential discrete CI in WFO PAH’s area today, we utilized the CONUS OCTANE Cloud Top Cooling product with LightningCast ABI+MRMS overlaid. As we watched the cap continue to erode through the afternoon, I noticed “popcorn” like cumulus developing that exhibited rapid vertical motion as detected by the OCTANE satellite imagery. Most of the activity that started to develop, though, quickly fizzled out due to the cold front being so far behind. Still, this was an interesting observation and a utility I find very useful for DSS operations. Outside of our area of interest, we got to watch how rapidly discrete cells developed south of Kansas City, and learned that there is a correlation being studied between how cool a cloud top gets and how instability exists in the environment.

Figure 2: Left Image: 18:32Z, Right Image: 19:22Z

We also learned today that we can analyze low-level winds with the OCTANE Speed/Direction sandwich. For the WFO PAH area, we observed more directional shear with low-level turning of winds. In this instance, I turned off the Speed layer and only had the Direction layer selected. This highlighted the area where low-level shear was greatest.

-simoom

Tags: None

Overview: Week 1, Day 1

Posted in Daily Summaries, Lightning Stoplight, LightningCast, SPG2026, Synthetic GXI, SZA Imagery on by Kevin Thiel.

9AM

Welcome to the testbed! Day 1 is usually when forecasters are just getting their feet wet with the products, but today they may get thrown into the deep end. The 13Z SPC Outlook features a Moderate Risk and large Enhanced-Slight Risk through the Mississippi Valley, driven by a 15% CIG2 threat. Forecasters will mostly be getting familiar with products and using AWIPS in cloud instances, but hopefully they will have plenty of good storms to observe today! Unfortunately we’re having issues getting the Lighting Stoplight tool into AWIPS, and it was only available online today.


1PM
We localized to Paducah, KY (PAH) and St. Louis, MO (LSX) with the expectation that semi-discrete thunderstorms would develop during our operations period. Unfortunately thunderstorms took too long to develop for PAH, but there was plenty of thunderstorms to the west across Missouri and north towards Illinois and Indiana.

We observed low level dry air from the Synthetic GXI data from a front and dry line that passed through western Oklahoma. It was interesting to compare the synthetic data from WVT and low(est) level water vapor at 5.15 µm against the observations from GOES-R in the split window difference and visible imagery at 0.64 µm. Some questions for the forecasters included how easy it was to identify features and boundaries in this clear-cut and more strongly forced scenario.

4PM

Later in the day our group also had a discussion about extremely large flashes as detected by GLM and the ground networks, and how (or if) they could be interpreted by products such as LightingCast or the Lighting Stoplight tool. Could LightningCast add lower probability contours? Would those contours add to noise and too many false alarms? How sensitive should users be to the appearance of probabilities?

6PM

To end the day, I saved off some animations of the SZA products. I tried adjust the Day Cloud Phase Distinction RGB recipe when including the Channel 2 and 5 SZA bands, so we will see how forecasters react to that product.
Kevin
Tags: None