Category: HWT

Single-Radar AzShear Product Showing Clearer Signal Compared with Merged Product

Posted in AzShear, HWT on by Thea.

The single-radar 0.5 degree AzShear (left pane) shows a coherent area of high values associated with the velocity couplet (bottom right pane). Compare this with the merged product (upper right pane). The merged product shows a few different maxima in AzShear which is probably associated with the multiple radars and beam heights that are used to make the product. The single radar product also tracks the velocity couplet better in real time and is not subject to the lag in the merged product due to the multi-radar processing.

Ron Dayne

Lightning Jump in GLM FED, but not Earth Networks data

Posted in GLM, HWT, Lightning Jump Algorithm on by Justin.

Storms continue just after 7pm near the Oklahoma/Texas border. A currently severe-warned storm saw a substantial and rapid increase in lightning activity observed by the GLM Flash Extent Density product. However, the ground based lightning network did not follow the same trend and remained fairly steady. The ground based data is more reasonable considering the storm did not experience any sort of significant strengthening during this time period. Earlier discussions with lightning detection experts suggested the low GLM FED count may be due to the location of lightning within the storm updraft region, which could impact how well GLM can sense it. That is difficult for the typical operational meteorologist to consider in real-time since it goes well beyond current training, and leads to decreased forecast confidence in the lightning data.

Dave Grohl

Mesocyclone Detection Algorithms Performance on Marginal Supercell(s)

Posted in AzShear, HWT, NMDA on by Justin.

A cluster to 2 merged supercells traversed across northern Oklahoma this evening. The loop below shows the performance of all three mesocyclone detection algorithms.

The legacy MDA performed the most poorly of all 3 detecting several inaccurate mesocyclones with inconsistent tracking. The DMD performed remarkably well in both tracking and intensity on the main meso  The NMDA experienced occasional dropouts where data was unavailable, but also performed pretty well on this storm. It particularly detected intensity well through the lifecycle of the meso.  The AzShear product also tracked the main mesocyclone very well. The DMDA performed best of all three for this storm  but the NMDA also showed promise. -Atlanta Braves

ProbTor/ProbSevere Impressive Performance

Posted in HWT, ProbSevere on by Justin.

There were 2 adjacent supercells heading into the Tulsa CWA and ProbSevere kept them as  separate objects (correctly) despite their proximity. This is a great sign. Additionally, the ProbTor product effectively differentiated between a tight couplet (north, 70% ProbTor) and a weaker couplet (south, 34% ProbTor).

This case shows the ability of ProbSevere to differentiate storms with distinct features despite close proximity. It also shows that ProbTor is doing what we think it should based on velocity features. -Atlanta Braves

TDS CPTI Evaluation

Posted in AzShear, CPTI, HWT on by Justin.

A tornado produced a TDS in the SW part of the Tulsa WFO CWA at 21:44Z. Maximum TDS height was ~6kft.

The CPTI adequately represented an increase chance of a strong tornado (18-20%, top left).

It appears this CPTI did not have the same issues with effective STP like yesterday’s St. Louis tornado did. I like this product a lot! -Atlanta Braves

GLM struggling with intensifying supercell

Posted in GLM, HWT on by Justin.

The first CI of the day occurred just after 19Z. The radar appearance of the storm remains healthy and the ground-based lightning networks are as strong as they’ve been, but the GLM strength has (erroneously) dropped off dramatically.

-Atlanta Braves

All-Sky LAP PW Showing Rapid Low-Level Moistening

Posted in AllSky, HWT on by Michael.

A comparison of the All-Sky LAP derived PWATs with 12z RAOBs shows that the LAP product is depicting PWAT quite well.

The PW retrievals were done mostly in clear skies (blue colors):

A four-panel plot of total PW and PW at different layers from 12-18Z shows rapid low-level moistening over OK and AR (upper right and bottom left panels).

The moisture return, in combination with diurnal heating, is resulting in a rapid increase in CAPE as suggested by the all-sky LAP product:

Ron Dayne