Many False Detections on CI at Night

As of around 23Z we have switched over to CI for overnight detection. The false detections appear to increase once this switch happens. There still appeared to be some utility though as it highlighted area over southeast WY that developed, but one would need to use it with caution overnight.

-JB

Simulated Satellite Demise of Storms

The long-lived supercell that moved from the DEN area into northeast CO appear to be weakening as of 2330Z and the forecast simulated satellite data did well in forecasting not only the initiation of the convection, but also in the early demise in northeast CO.

-JB

Overshoot Top to Indicate Strong Storm

I was using the Overshooting Top application and it showed one over the one storm for a couple of updates.  This led me to believe it had a strong updraft and then I looked at Prob Severe and it also trended up so I was going to issue a severe t’storm warning.  Now I want to see if this verifies.  ~ Vollmar

Simulated Satelite imagry from earlier.

WRF Simulated Satellite imagery from around initiation time. Initiation time for the simulation was running about 30 to 60 minutes delayed from reality. Not Good but Not bad if the WRF data arrived more than 1 hours early. I also want to point out that it did capture the main storm of the day and roughly the correct placement for initiation.

First hints of initiation in Reality 1915Z.




First hints of initiation in WRF Simulation 20-21Z time frame.

Grant H.

One last Midwest storm, for good measure

Just exiting our operations area, a storm on the Indiana/Ohio border evolved in the midst of many other severe storms in the region (see the featured storm below). This storm had strong normalized vertical growth and glaciation rates by 19:15 UTC. This information jumped the probability of severe from 6% to 55% at 19:20 UTC, when the MUCAPE, effective shear, and MESH remained constant. The ProbSevere value increased to 85% by 19:26 UTC, with a MESH = 0.56". The first NWS warning was issued at 19:39 UTC (13 minutes later). One inch diameter hail was recorded at 19:52 UTC.

-Cintineo/Sieglaff

Tracking tool. Just not ready for prime time.

Gave the tracking tool a second chance today.  Bad results. It appears to be a computational issue. I had loaded a 60minute Composite Reflectivity off of MRMS for it to compute. It allowed me set up the circles nicely… however when it started graphing it would only display 2 minutes of difference on the graph initially. About 3 to 5 minutes later It was displaying  4 minutes, 3-5 minutes later it was displaying 6 minutes. So 2 minute increments.

All panes were active while I was grabbing this first screen shot. However, while realizing that both panes were not in the shot; I went back to grab screen shots of the meteogram itself, and discovered that all panes had locked up. A couple minutes later All of CAVE had crashed as if the system had run out of memory.

Grant H.

Anvil Flashes in PGLM

Here are two examples (2148 UTC and 2153 UTC) in northeast CO of how PGLM can be used to detect flashes that propagate long distances into the anvil of storms.  Above is 0.5 km reflectivity, with flash extent density (FED; colored boxes) and NLDN strokes (minus signs).  The highest concentration of flashes is near the updraft core (42 flashes min per pixel), however, note how the flash extent extends well into the anvil region of the storm.  This highlights a region where lightning potential exists.  In the top panel, two NLDN flashes occur in the circled area and in the bottom panel, extensive anvil flashes are noted, but no NLDN information exists in the region where the PGLM shows flash propagation.

Chris S.

Warnings based on Prob Severe

I used the Prob Severe tool today and watched the trends for some of these storms.  It was intensifying the storm each update by 10% and once it got above 60% I warned it.  Sadly the next two updates the storm weakened and so I feel a little let down by Severe Prob.  I may not have needed to issue in the first place.

Missed Hail Event: PROBSVR and MRMS Data

1 inch hail was reported in Union County OH around 2130Z.  The PROB-SVR maxed at 47% a few minutes later and was about 30% at the time of the vent.  MEHS briefly peaked at .7 inches.  However, numerous signatures within both of these products have moved over populated areas without producing severe weather reports.  It seems to be fairly tricky today to get a bead on the severe/non severe thresholds for various experimental products within the ILN CWA.

- JRM

ProbSevere vs. LJDA

One of our primary goals today was to examine the relationship between the ProbSevere model and the lightning jump detection algorithm. A strong storm fired on the front range of the Rockies, just west of Denver. The ProbSevere model noted strong satellite growth rates in a moderately-sheared environment, with MESH only 0.17″. The probability of severe was 33% at 1920 UTC.  At this time the PGLM indicated a flash rate on the order of 6 flashes per minute.  Two minutes later, at 19:22 UTC, the ProbSevere was 46%, as MESH increased to 0.33″, and the total flash rate at 8 flashes per minute per pixel.   Over the next 4 minutes, two consecutive lightning jumps were indicated in excess of 2 sigma as the total flash rate rose from 8 to 20 flashes/min/pixel (2 sigma jump at 1922 UTC, 4 sigma jump at 1924 UTC).  ProbSevere increased to 66% at 19:24, and 77% at 19:26 (MESH = 0.71″).  This storm intensity information highlighted the rapidly developing updraft within the storm; signalling the potential for severe weather was increasing as the first storm in the area approached the Denver Metro Area.The NWS issued a severe thunderstorm warning at 19:36 UTC. The jump in ProbSevere (46% to 66% from 19:22 to 19:24 UTC) and the 2-sigma and 4-sigma jumps from the LJA (at 19:23 and 19:24 UTC, respectively) may be able to give forecasters enhanced confidence and perhaps more lead time to initial rapid development in the storm, and potential severe hazards. Animated GIFs for Flash Extent Density (top), Lightning Jump Detection Algorithm (middle), and ProbSevere (bottom) from 1920 UTC to 1930 UTC can be seen below.

Additional lightning jumps were noted at 1943 UTC (3 sigma) followed by multiple 2 sigma jumps at 2000 UTC, 2001 UTC, and 2004 UTC, and another 3 sigma jump at 2005 UTC.  These additional jumps were additional signals that the updraft in the storm was re-intensifying and continued to have the potential to produce severe weather.  Thus any warning that was issued should remain in effect. During this time period, ProbSevere remained at or above 98%. The first tornado report associated with this storm was at 2005 UTC and hail to the size of golf balls were reported in the Denver Metro.  Also hail depth of at least 5 inches was reported at Denver International.

In this case, ProbSevere and LJDA both displayed the rapid intensification of the updraft, and could be especially useful in identifying the first severe storm of the day, and the maintenance of the ProbSevere and additional lightning jumps continued to highlight the threat of severe weather as the storm continued eastward as the storm propagated eastward.  This information is a high temporal resolution (1-2 minutes) and provides additional data points that can fill gaps between radar volume times.

-JC,CS,BW