Loaded the one minute SPoRT Flash Extent Density product and used the editable Moving Trace tool. The moving trace circle had to be expanded for each frame; forecasters won’t like this because it doesn’t have a “apply to all” feature for this. It is also not intuitively obvious to forecasters that have been using other tools such as the warngen pathcast tool and distance/speed tool in AWIPS. The trace tool makes a graph showing “Flash Extent Density”, which showed trends in lightning for the selected storm.

1914 UTC Flash Extent Density. This product could be useful for NWS event support to describe specific lightning threats to outdoor activities. It could also be useful to identify strengthening updrafts that could produce large hail. One storm that showed a quick spike in Flash Extent Density above 50 Lma at 1912 UTC went on to drop 1 inch hail at 1926 UTC, for a 14 minute lead time. See Becca’s blog entry on this storm.

There were several bad one-minute data samples caused by loss of input data into the Oklahoma LMA. Two of them are illustrated below.

One minute Flash Extent Density showing the sharp drop that was apparently the result of a temporary loss of input data into the Oklahoma LMA. This occurred again at 1948 UTC see the trace graph below.

Warning operations began with a series of small mesocyclones, the first of which had a small hook echo. Tornado warnings were issued for three storms. A 0.5 slice of the OUN R/SRM was primarily used for storm interrogation and the 30 minute Oklahoma Surface and Mid-Level Rotation Tracks were used to see the right-turning trend for meso paths.

Top image showing OUN reflectivity of the first tornado-warned storm. Bottom image is OUN SRM showing another tornado-warned storm’s meso circulation.

The trends shown on the rotational track products helped in narrowing the tornado warning polygons and thus minimizing the false alarm area for the tornado warnings. The surface rotation track was also used for evaluating whether a tornado warning would be needed for southern Jefferson County as a tornadic supercell moved parallel to the Red River. It also was a great way to show the cyclic nature of this meso.

MRMS Sfc Rotation track showing the redevelopment of the mesocyclone further east. The loop of this product helped save a false alarm tornado warning for Jefferson County.  The rotations along the line of storms were also shown, but the entire line was plotted in sequence, which avoids a noisier picture of the track. See image below.

Another interesting thing noted with the rotational track algorithm was the inclusion of a rotation signature with range folded/improperly dealiased velocity data.

These images are from around 0050 UTC 16 May, showing an area of range folding and bad velocity data that was plotted as an area of rotation by the SRT.

– Ostuno

Rapidly developing convection showed a rapid increase in flash extent rates in the low teens to the mid 30s with a few pixels spiking in the 40s. This activity rapidly morphed into a bow echo that raced across south central Oklahoma. The SRM velocity gradient along the front end of the bow was very tight…and the rotation tracks product showed an interesting progression of bow-like rotation signatures from north to south. There were gaps between each line (seen in the graphic below) unlike a single storm track which is fairly continuous.

At the north end of the bow…the values of the rotation tracks were strongest which is to be expected in the region of the northern bookend vortex. The flash extent rate was relatively weak with the bow…along with weak sfc velocities estimated to be around 20 kts from mesonet observations. So although the reflectivity structure looked as if it could be an intense bow echo with moderate midlevel convergence…and rotation tracks were depicting embedded circulations within the line…no reports of severe wind or damage were reported or observed.

The highest values for sfc rotation tracks around 23s-1 were in the vicinity of the bow where smaller cells were merging with the main line near the northern bookend vortex. The best velocity couplet depicted on SRM went between Byng and Francis around 2349Z and was just southeast of the highest values for the sfc rotation tracks.

The LAPS_OUN_1km surface instantaneous updraft helicity from the 22 UTC run captured the tornadic supercell near 00 UTC between Mineral Wells and Fort Worth, Texas.  The 0015 UTC instantaneous updraft helicity from the 22 UTC run is depicted above.  The kfws 0.5 reflectivity at 0015 UTC is depicted below.  The instantaneous updraft helicity is maxed out very close to the location of the supercell. The 21 UTC LAPS_OUN run indicated some potential for tornadic supercells across northwest Texas 23-24 UTC, which was about 50 to 100 miles too far northwest than what actually occurred. Michael Scotten

LAPS_OUN 1 km did a fine job capturing a bow echo over southern Oklahoma and isolated supercells northwest of the Dallas/Ft. Worth metroplex with 1-3 hr of lead time.

The top image is the 2 hr forecast for 00 UTC 16 May 13 from the 22 UTC run 15 May 13. The bottom image is 0.5 reflectivity from kfws at 2353 UTC.

As mentioned a bit earlier in a post, the NearCast product showed enhanced chances for convection all the way to the Lubbock area. Especially the theta-e difference product placed the tongue of mid-level unstable air just where high based thunderstorms finally evolved. Surface dewpoints in the mid 30s and temperatures in the low 90s point to elevated and high based thunderstorms with a distinct downburst/ heatburst? risk. The product helped a lot to focus on the anticipated area of initiation. GOES-R LAP products also did a great job in developing the elevated thunderstorm activity both in space and time.  HelgeUpper left: vertical theta-e diff., upper right: Sustained convection index, lower left: CAPE and VIS in the lower right.

Isolated thunderstorms have developed in the Vertical Theta-E Difference Low-Mid maximum, east of the dryline, across the north half of Texas, just west of I-35 around 23 UT.C This product may be a better indicator of moist convection east of the dryline then the dryline itself.

I was monitoring storms in Clay/Montague counties and potential CI further to the S/SW. Broad field of Cu was seen further south but it was hard to distinguish which of those Cu fields would finally grow into a thunderstorm.

Upper left: Cld top cooling product, upper right: CTC accumulated, lower left convective initiation and lower right: reflectivity

Please have a look at Palo Pinto county, where the CTC product had a 80-90% signal strength of showing initiation potential (the lower orange dot). At the same time in the reflectivity fields only a few weak signals were seen.

About 30 min later, the CTC instantaneous product showed a modest signal of -15K/15 min over the NE part of that county with reflectivity appraoching 40 dBz at the same time and place.Finally at 2230 Z reflectivity revealed a small core with 60 dBz. The first lightning strike occurred at 2237Z. Those products gave the forecaster a good indication which area would finally see the highest probabilities for thunderstorm development and there was abundant lead time left before that storm finally took off. Helge

The GOES CI product detected a 60% yellow area at 2045 UTC.  By 2115 UTC, a thunderstorm had developed in this yellow area.  This storm strengthened and prompted the issuance of a Severe Thunderstorm Warning by 2205 UTC. Baseball hail was reported by this storm at 2212 UTC, and a tornado was observed around 2242 UTC.  The CI product gave about 20-30 minute lead time for storm development, 75-90 minute for severe weather, and nearly 120 minutes of lead time for the weak tornado.

Michael Scotten.

Got a tall and strong storm in Montague County in the northwest corner of the FWD CWA.  It built up very quickly, and we almost were too slow with the warning.  Below is a four panel of various MRMS fields:  upper left=mid level rotation tracks, upper right=height of 60 dBZ echo above -20C level, lower left=MESH, lower right=hydrometeor class with HSDA.  Note the orange MESH pixels, showing 2.5″+ hail, as well as the area of large/giant hail on the HSDA product.  The warning went out at 2205Z, and we got the first reports of golfball/baseball sized hail at 2208Z.  Just in time!

CL

The 18Z LAPS 4-hour forecast of sfc layer maximum reflectivity showed the development of a large, supercellular storm near the Gray /  Montague border.

Here is the actual reflectivity image from 2204Z.

Golfball- to baseball-sized hail has been reported with this storm.

Picca