The vLAPS 1 hr Simulated Reflectivity image is the top image from a run at 23 UTC, valid at 0015 UTC (75 min later), did a fairly good job representing actual base reflectivity from KCLE at 0016 UTC in the image below.  The simulated reflectivity seemed to perform best in western Pennsylvania and West Virginia.  The reflectivity may have been overdone in western Ohio.

Michael Scotten

After diagnosing the CI tool once it switches to the coarser resolution using IR, I just don’t think it’s usable.  It’s way too noisy and very inconsistent, almost unusable in my opinion.  I love this tool during the day, but I honestly just don’t think it’s worth the data crunching to run at night.

– Deitsch

The GOES-R Overshooting Top Detection (OTD) product continues to underestimate the number of overshooting tops.   In the top image at 2315 UTC, there are several cold cloud tops around -60C with several severe storms in Ohio, western Pennsylvania, and West Virginia.  The OTD product only detected one overshooting top over Ohio at this time.

The OTD product seems to be underestimating the number of overshooting tops today on May 14.

Michael Scotten

The ProbSevere model was useful in spotting a convective cell that popped up in the Pittsburgh area late in the afternoon. The rapid scan GOES imagery, overlaid with ProbSevere, shows a few cells worth keeping an eye on. The northernmost shapefile in pink was in an area that I otherwise would have ignored, because I didn’t see any visual cues in the visible imagery that indicated convection in the immediate area of the pink outline.

At the time when I was looking at this cell, I also had the Theta-e differential overlaid, to see if that was pointing out any unique features. I dialed down the opacity of the color table so it wouldn’t interfere too strongly with the high-res sat data. For the picture below, I pushed the opacity back up to clearly show the colors. As you  can see, there is a relative maximum over the ProbSevere shapefile of about -9.0K, but without the ProbSevere shapefile, this area wouldn’t have caught my attention, since there are other areas with that same intensity, and the values weren’t too impressive, either. That said, the -9K blob on the right was in an area with developing Cu, whereas the blob on the left didn’t have Cu development yet. So I guess in retrospect, I could have taken notice to the area with relatively high Theta-e difference in conjunction with the developing clouds. I do feel like the ProbSevere gave a jump on any visual confirmation I might have made on changing cloud structure, because like I said before, the clouds did not look that impressive to me.

The vertical PW difference wasn’t showing any impressive values, either, but something that’s worth noting is the gradient that formed right in the warned area. As we know, gradients are conducive to volatility, and the storm’s path actually tracked right along this gradient, moving due north. The image below is valid at 22:00Z. A warning was issued in the circled area at 22:27Z.This cell had been warned earlier in the afternoon, and redeveloped. The ProbSevere model might prove to be very useful for tracking storm cells, not just before they become severe. It could also be useful after a storm loses its severe characteristics by tracking its redevelopment potential.This could be very useful for a forecaster to help them sift through the clutter, especially in events with lots of pop-up cells and in linear MCS events.

The following three images follow a cell northward across north-central WV using the ProbSevere Model overlaid on KPIT 0.5 degree radar reflectivity. The first image below is from 2224z where the sampling box shows the ProbSevere model with a 6% probability of a severe storm. The Multi-Radar Multi-Sensor MESH size was 0.17 inch within an environment of 2135 J/kg MUCAPE and 21.2kts EBShear. There was strong vertical cloud growth rate and a moderate glaciation rate calculated from satellite imagery.

14 minutes later at 22:38z the ProbSevere Model severe probs jumped to 95% with the only change in the predictors being an increase in MRMS MESH to 1.74inch.

9 minutes later at 2247z a three-body scatter signature (between the annotated arrows) shows up on the KPIT radar to the south of the storm core. At 2254z golf ball sized hail was reported in Salem, WV.

Shawn Smith

The GOES-R Convection Initiation product handled developing convection in West Virginia with 15-45 minutes of lead time on May 14.  The top image displayed visible imagery with CI values along a few bands of enhanced cumulus with values 51-84% highlighted in the green, yellow, and orange areas at 2015 UTC in the middle part of West Virginia.  The second image with RLX reflectivity depicted very little to no convection at 2015 UTC.  The last image depicted RLX reflectivity at 21 UTC with isolated to scattered storm development where CI values were 51-84% about 45 minutes earlier.

This product continues to perform very well.  CI values greater than 50% have been shown to indicate developing convection with high confidence.

Michael Scotten

The CIMSS NearCast forecast 900-700mb precipitable water values are shown below at 22 UTC (top image) and 01 UTC (bottom image).  It appears that 900-700mb precipitable water values will decrease across Ohio from 13-16 mm at 22 UTC to 7-12 mm at 01 UTC due to drier air moving in from the south.  This leads to the following question, will storms dissipate?  We will see…Michael Scotten

The image above is a screen capture of radar and lightning data centered over the OHX (Nashville) CWA at 21:54z. Today we evaluated the Lightning Jump Detection Algorithm since the OHX CWA was within coverage of the Northern AL Psudo-Geostationary Lighting Mapper.

In the four panel above focus on the top two panes where the top left has 0.5 reflectivity from OHX radar overlaid with the Lightning Jump Detection Algorithm (Grey) and 5 minute NLDN Cloud-to-ground lightning data (+ and – in red). The grey of color of the Lightning Jump Detection Algorithm only indicates 0-1 sigma or 0-1 standard deviations of the previous 10-minute change in flash rate. Significant jumps (increases in sigma) in lightning activity are correlated with severe weather. The top right pane shows OHX Enhanced Echo Tops. The convection observed in the top right pane was a low-topped QLCS as indicated by Enhanced Echo Tops of only 20-25kft. During the evaluation period of 20-22z no significant lightning jumps were detected due to the low-topped nature of the QLCS. Had the storm updrafts and tops been taller (upwards of 40-50kft) then lightning activity including jumps may have had a better chance of occurring.

Shawn Smith

Here is a look at the vLAPS forecast at 20Z, valid at 2215Z.  The forecast is a 2 hour and 15 minute forecast.

Here is the observed reflectivity data overlaid on top of the model forecast.  The model is doing pretty well!  It has pretty good placement of the storm cluster, and it hints at supercellular storm modes, which is what is currently being observed.  Helicity was not available at this time.

Storm development was occurring on the western edge of the CIMSS NearCast 780mb equivalent potential temperature gradient across Ohio on May 14.  The NearCast products have been shown to benefit short term forecasters by indicating changes in moisture in an area where storm development is expected.

Michael Scotten