Buttermilk gets churned

An eastward moving supercell narrowly misses the town of Buttermilk, KS. ProbSVR was consistently above 90%. The previously tornado-warned storm lost a low-level circulation and ProbTOR dropped to <10%.

The 1-min visible satellite imagery of the storm around sunset revealed persistent overshooting tops and an above anvil cirrus plume with this storm. The above anvil cirrus plume is an indicator of a particularly strong updraft and potentially severe storm. A flanking line is revealed on the southwest portion of the storm as it advances through Buttermilk

 - SCoulomb and Bucky

GLM flash area product

GLM flash area product shows a nice correlation between the overshoot in VIS and a small (~110 km2) flash size. Flash size increased in the anvil downshear from the updraft and reached values ~420 km2. The highest total energy values were downshear from the overshoot. FED values (no shown)

were 1-2 in the same region.

Possible Tornadic Circulation in southern Dodge City, KS WFO

Early Tuesday evening, 0-1 km storm relative helicity had increased over the Central and Southern Plains.  The DDC crew noticed a rapid jump in ProbSevere All Hazards probability of tornado between 2328 and 2336 UTC--going from 10% to 70% in the 8 minute time period (Figure 1) in Comanche county, Kansas.  The forecast crew said the rapid increase alerted them to a rapidly intensifying low-level circulation and prompted an experimental tornado warning at 2339 UTC.

Figure 1.  KDDC 0.5 degree storm relative velocity and ProbSevere All Hazards probability of tornado contours 2328 - 2336 UTC 01 May 2018.

-J. Sieglaff

1-min VIS/IR During Warning Ops

During convective warning operations, I prefer to have a 2-panel VIS and IR display for monitoring storm top convective trends. Persistent features such as overshooting tops and above anvil cirrus plumes indicate particularly strong updrafts and long-lived storms. This was the case with many of our storms today, including that shown below.

- Bucky

another bad ProbSVR DDC

Another ProbSVR contour appeared where no echoes existed in the base reflectivity for KDDC. MRMS Composite reflectivity showed  an apparent old volume scan still being used.

GLM Trends

Here is a 4-Panel lightning loop near the Nebraska/Kansas border.  The loop is 30 minutes long.
Upper Left: 1-minute GLM Flash Extend Density
Upper Right: 1-minute GLM Average Flash Area
Lower Right: 1-minute GLM Total Energy
Lower Left: 0.5 Reflectivity with 1-minute Cloud to Ground ENTLN lightning Plot overlayed.

Upper Left: Notice the one area with a higher Flash Extend Density.  It's indicative of a stronger, consistent updraft.  There is more mixing of the charges going on, which is helping to generate more lightning activity.
Upper Right: Notice the area where the higher updraft should be.  It has a general lower flash area.  This is because there there are more flashes happening at a lower threshold due to the mixing of the charges.  However, there is the occasional jump in area (a brighter color).  This is because charge increases over time in the anvil.  Then, when lightning happens in the anvil, it has more charge.
Lower Right: Notice the energy is higher where there is more lightning activity, generally near the updraft.  It's like viewing the overall wattage of the storm using a high-speed camera.
Lower Left: 0.5 Reflectivity with 1-minute Cloud to Ground ENTLN lightning Plot overlayed.  Keep in mind, the GLM data has a parallax error.

-Kevin

Second Warning in DDC Utilizing ProbSevere

For the second storm, probabilities increased to 84% with MESH only at 0.41". Similar to the first storm, probabilities were high despite the lower MESH given a favorable environment and lightning. Given my experience with the first storm (low MESH but high ProbSevere probabilities), the increasing probabilities in this situation led me to issue a severe thunderstorm warning, again slightly earlier than I may have based on the all tilts depiction. This storm went on to produce severe hail.

- Bucky

A few quick ProbSevere All Hazards Comments from a Forecaster

With such a busy afternoon of severe weather over the WFOs of interest, I was able to ask a forecaster if he had any comments on performance of ProbSevere All Hazards so far today.  He said, "it is performing very well and I am very happy to see ProbSevere All Hazards performing well with left moving supercells after storm splits, as often algorithms struggle with these types of storms".  He also added, "I was going to severe warning on this right moving supercell, and noticed ProbSevere All Hazards probability of tornado was up to 40%, while I wasn't confident enough to go tornado warning, I added the tornado possible tag to my severe warning".

-J. Sieglaff

First Thoughts in CYS (Cheyenne, WY)

There are too many submenus to open GLM. A more streamlined menu suggestion is to have GLM a dedicated submenu after 'GOES East and GOES S', instead of under 'Derived Products'

NUCAPS plan view parameters are inconsistent both spatially and temporally. For instance, 19Z pass omitted just about all of the CONUS.
NUCAPS modified and unmodified DB soundings are identical.

AllSkyLAP CAPE product appears to be underestimating instability across the domain area of sern WY/nwrn CO

ProbSevere with First Storm in DDC

ProbSevere was utilized in DDC as an overlay on base radar reflectivity.  The progression of probabilities is displayed in the animation and individual images below. From 2008 to 2010 UTC, ProbHail jumped from 39% to 58%, based on a slight increase in MESH from 0.40" to 0.51". and flash rates increasing from 6 to 16. From 2010 to 2012, ProbHail increased to 95% and MESH to 0.73" and flash rate to 34. This is valuable to note: Despite MESH still well below 1", ProbSevere is at 95%, indicating high likelihood of severe (hail in this case). A key driver being favorable lightning in a favorable shear environment. The rapid trend up in probs combined with high probs helped to provide confidence in the warning decision. This despite the fact that MESH was still well under 1", and the reflectivity core was still on it's way up, but not quite to where I would want it for my typical warning decision. This storm quickly produced melting 1" hail, and later 1.5" hail.

- Bucky