GLM Observations

As storms were initiating I turned on GLM and NLDN to watch GLM show cloud to cloud in advance of cloud to ground.

Sure enough, the first 3 bolts from GLM appeared at 2131z.  It was not until 2138 that a negative stroke appeared on NLDN.

This confirms that cloud to cloud occurred about 7 minutes before the first cloud to ground.

Davis Nolan
WKRN Meteorologist

Observation of Gridded NUCAPS data with Tropical Storm Cindy...

I thought it would be interesting to see how well NUCAPS data would be available with Tropical Storm Cindy in the northern GOM considering drier air aloft is wrapping into eastern parts of the system, and is generating perhaps increased instability in partially cleared areas.  The first image is a simple 0.64 um GOES-16 image from around the time the NUCAPS data were available, at about 19Z.

The next image below shows 925 mb Theta-e observations around the system, where available.

Notice that in the areas with more absence of clouds in the astern flank of the system and wrapping into SE-S Louisiana...there is a distinct gradient of theta-e according to the data.  Also, in NE Texas, where there was some partial clearing, this gradient was also noted in the low-lvl theta-e field.  However, also notice the relative higher values of theta-e in SE Texas, near and just west of Houston. Not only did this show up in the 925 mb theta-e field, but also in the 850 mb layer...

This area of relatively higher theta-e that developed over the land surface would then wrap into the circulation and help to induce deeper convection during the afternoon.  This loop of 0.64/10.34 um imagery shows this development of deeper convection on the W-NW side of the circulation subsequently.  Although, it should be pointed out that there could have been a number of additional factors that helped to contribute to the subsequent increase in deep convection.

Kris W

Satellite Linked to Radar Observations

In the example below, we can see the link between satellite imagery and radar observations.

• As the cloud top cools, radar reflectivity intensifies in the storms
• As the cloud top warms, radar reflectivity weakens in the storms

This shows the benefits of higher spatiotemporal satellite data--especially in areas of poor radar coverage--to monitor the intensity of storms.

-Lost Met

NUCAPS for 0C and -20C levels

CAPE has been readily evaluated using NUCAPS, but another use of these soundings is to quickly find the 0C and -20C levels. Many other tools use model data which can have their own errors, but the NUCAPS is actual observation and can bring more confidence when analyzing storms in the vertical.

As storms are beginning to develop across the FGF CWA, I wanted to have the 0C and -20C levels on hand. I quickly went to the latest NUCAPS pass and pulled a sounding within the region. Forecasters do not need to wait for a modified experimental sounding to come in for this data.

I found this information very valuable during warning operations. I had the heights of these two levels on hand when I was doing storm interrogation. I used these heights when assessing heights of 50 and 60 dBZ, which helped in my warning issuance. 

-Ironman

GID: Environmental Analysis (NUCAPS (non-experimental) and GOES-16 Derived CAPE)

NUCAPS and GOES-16 Derived Stability Comparison.

• Notable CAPE gradient across GID with CAPE values below 300-400 j/kg across the far western CWA. 
• 19z NUCAPs soundings revealed MLCAPE higher and around 1700 j/kg along the far western gradient when modified to sfc obs. Using the modified NUCAPS sounding was beneficial in that it looked like mid-level cap would be able to be overcome with continued daytime heating which would allow for deep convective activity.
• 1st cells developing in this area but haven't shown deep growth as of yet. As of 0030z the cells have been slow moving and are just starting to approach the CAPE gradient. Cell have been noticeably been starting to trend stronger and 2 severe thunderstorm warnings have been issued in western CWA.

-Tahoe. 

Montioring for Convective Development Across FGF

I displayed the 2 windows side by side in AWIPS. Surface data was not included, but the sandwich on the left with Radar and baseline derived CAPE together was a good way to monitor for convective development. Two distinct fine lines were on radar, one to the west with the cold front and one to the east with the warm front. Surface obs confirmed these boundaries. Behind the warm front and ahead of the cold front, there is a tongue of increasing instability and signs of convective growth on the GOES-16 imagery.  This setup may prove useful to monitor trends before an event or even as situational awareness.

- Ironman

Convection Approaching Higher Instability

By overlaying visible satellite with derived CAPE, it's obvious that the convection is approaching higher instability across central and eastern Nebraska:

There, we would expect thunderstorms to intensify as they shift east into higher instability.

-Lost Met

GOES-16 TPW Comparsion

GOES-16 TPW has done a good job capturing the general trends of preciptable water.  Here is a comparison of GOES-16 TPW and SPC Mesoanalysis:

Both should very moist values in association with tropical storm Cindy (>=2.2") and then a dry corridor across central Texas into southern Oklahoma.

-Lost Met

Usefullness of Simple Water Vapor RGB

Once an explanation of how the colors worked on the simple water vapor RGB, I found it useful as a quick situational awareness tool that can save some time or panel space in AWIPS, instead of using all 3 water vapor channels at one time.  I also like how it includes the clean IR channel so you can see all the way down closer to the surface and see where convective clouds may be growing/developing.

I also recommend having sampling on to see the contribution values.

Tropical Storm Tornado Warning

Second Tornado Warning: New Orleans CWA.

• Second tornado warnings issued for a mini super cell. Gate to gate velocity was about 60kt on average. 
• ProbSevere outlined a large area but did seem to latch on to good environmental parameters such as helicity, shear, and instability. 
• The quick moving and evolving nature of mini-super cells may put ProbTor at a disadvantage if processing using MRMS data is lagging behind due to processing. We've noticed the ProbTor increase, but mostly after the cell is already dissipating. Thinking this could be a data lag. 

--Forecaster: Tahoe