UWCTC Captures Developing Severe Convection in SE Kansas

CTC captured developing convection that eventually turned severe in the ICT WFO.  The initial and only UWCTC cooling rate was diagnosed to be strong at approximately ~-22K/15 min (see Figure 1) during the 2332 UTC scan. 

Figure 1.  UWCTC over visible imagery valid at 2332 UTC.  The cooling rate was ~22K/15 min.

The base scan radar imagery out of ICT at 2329 UTC had a precipitation core on radar with approximately 50 dBZ radar reflectivity (Figure 2).  No severe warning was issued at that time (The warning shown on the screen near the echo was issued at a later time).

Figure 2.  Radar imagery from ICT WFO.  Storm of interest is NE of radar site.

A severe warning was issued by the ICT WFO at 0016 UTC for this storm with the threat of quarter size hail and strong winds (Figure 3).  No hail reports were received as of this blog entry for verification of this severe warning.

Figure 3.  SVR from ICT concerning storm of interest.

Figure 4 shows radar imagery valid at 0032 UTC for the same storm.  Notice the stronger reflectivity in the core of the storm.  The strong UWCTC rate had a lead time of ~45 minutes over the severe warning that was issued.  Again, no hail reports were received so far.

Figure 4.  ICT base reflectivity valid at 0032 UTC.

Flash Extent Density Jump

One cluster of storms over southwest Oklahoma produced the most impressive FED signal of the day. While we’ve had a warning out for this storm for some time, no reports have been received, and MESH has kept values generally at or below one inch.

**Update**

One rapidly intensifying cell has shown a lightning jump with up to ~50 flashes/min and is likely producing severe hail per MESH.

PGLM Total Lightning Data Aids in Warning Issuance

A rapid ramp up in total lightning data led to increased lead time for a Severe Thunderstorm Warning this afternoon. The Flash Extent Density product increased to 19 flashes per minute prior to warning issuance.

Flash Extent Density product showing an increase to 19 flashes per minute prior to warning issuance.

Flash Extent Density further increased following the warning as severe hail was reported.

Flash Extent Density product increased to 32 flashes per minute as severe hail was reported.

Frank/Guseman

High and Mid Cloud Contamination Limiting Use of GOES-R CI and CTC Products

Early high and mid cloud contamination from an approaching upper-level jet limited use of both the UAH CI and UW CTC products across northwestern Oklahoma this afternoon. Storms initiated around 3 pm with the first Severe Thunderstorm Warning issued around 345 pm. The UAH CI product never showed any signs of CI due to this cloud contamination, but the UW CTC product did briefly show some signs of severe storm development as it provided an approximate 20 minute lead time on the first warning issuance. Previous shifts had found longer lead times utilizing the CTC product, but the extent of upper and middle cloud contamination was not as pronounced during those cases.

4 panel imagery showing nothing from the CI product. The CTC product did briefly pick up on cooling rates near 15 C/15 min at 2025Z.

Same as above at 2032Z, with CTC showing cloud top cooling rates greater than 20 C/15 min.

CTC product continued increasing to greater than 25 C/15 min with storm motion toward the northeast at 2040Z.

Both the UAH CI and UW CTC products show nothing as mid and high clouds continue streaming in with mature storms at 2045Z.

Frank/Guseman

Large CTC Values Providing Excellent Lead Time for Severe Hail

Developing supercells over the TX panhandle became severe appox 30 to 45 min after a significant CTC signal. This signal is shown below in the upper left corner of the 4 panel. 30 to 45 min. after the minimum CTC value of -33, MESH indicated 1 inch or larger hail. This is displayed in the second image below. Of note is how well the CTC algorithm is performing despite a modest cirrus shield.

Austin

EWP2013 8 May 2100 UTC Mesoscale Discussion

We are actively monitoring convection across western OK and the TX panhandle. At 4 pm our area of operations will be the OUN CWA.

 MRMS QC Composite Refl, MRMS mid-level rotation tracks, MRMS dbz at -20 C, HCA/HSDA

High 50s/low 60s dew points are continuing to pool across western OK as observed on the OK mesonet.

2035Z Mesonet

The OUNWRF appears to be capturing the current dewpoints correctly over Oklahoma, especially in the area where convection is developing. However, the temps ahead of the convection appear to be too high on the OUNWRF. It is possible that this is contributing to the over-development of convection on the OUNWRF (as seen spatially on the simulated reflectivity products).

LAPS analysis from the 1 km OUN domain continues to do a decent job with the placement of the composite reflectivity across western OK. Interestingly enought the 21z LAPS shows a clean swath of 2200 to 2600 J/Kg SBCAPE spreading northward across western north Texas, with another pocket of 2000 to 2500 J/Kg SBCAPE near the OK/KS border, which would be nearer the sfc low which continues to churn E/NE across the TX panhandle.

SFC layer-max base Refl, 1km SBCAPE, 1km sfc Lifted Index, SBCIN

Early convection this afternoon developed in a sct to bkn area of cumulus, with scattered cirrus/stratus spread across Panhandles through western OK. This has resulted in little to no response from the both the GOES-CI and CTC products due to the contamination from the cirrus and stratus. The screen capture below shows the area of intense convection developing over Oklahoma, with little to no apparent signals in the CI/CTC products. This was also the case for several time steps before this image was saved.

CI, CTC, and IR

Nearcast products from CIMSS/GOES have also struggled with the presence of clouds before convective initiation. This is evident from loss of data across western OK and the TX panhandle.

PW Diff, Te Diff low-mid, Convection Index (K^2mm), 780-500mb CAPE

Kurtz/Hatzos

CTC Signal Lead Time over First Operational Warning and Hail Report

Thick cirrus was preventing CTC from tackling any of the early convection over Oklahoma; however, where the cirrus shield has dissipated/cleared, we're getting some good CTC values.  An example of this is over extreme northwestern NM into the panhandle of OK.  The first CTC signal for the storm of interest was at 1825 UTC with a weak value of ~-8 to -10 K/15 min (Figure 1).

Figure 1.  UWCTC over extreme northeastern NM with a value of ~-8 to -10 K/15 min.

The very next scan at 1832 (Figure 2) exhibited a moderate CTC rate of -15K/15 min with the growing storm.

Figure 2.  UWCTC over extreme northeastern NM with a value of ~-15K/15 min.

The first severe warning for this storm was issued at 2003 UTC.  Lending a 38 minute lead time over the operational warning being issued.  Below is the radar imagery from KAMA valid at 2044 UTC.

Figure 3.  KAMA radar imagery valid at 2044 UTC when the second warning was issued.

The first hail report received at AMA was at 2037 UTC with 0.88 inch hail being reported by law enforcement (a little over an hour lead time for CTC).  The LSR text is shown below in Figure 4.

Figure 4.  LSR report from AMA WFO for hail in panhandle of OK.

PGLM Flash Extent Density Unusually Low for Severe Supercells

Below is a 4 panel image of Flash Extent Density, Composite Reflectivity, and MESH. With two supercells indicating large hail via MESH, one would expect larger values of FED, which have only maxed out around 5 flashes/min. However, this may have something to do with distance from the LMA centroids. We will continue to monitor. In any case, the PGLM products are very useful for aviation and public safety interests for points downstream.

**Update 2107 UTC**
Monitoring the storm following Flash Extent Density Trace Tool, it appears many of the storms have entered a period of decreasing lightning activity. This is also apparent in the plan view of FED. This would suggest a downward trend in storm severity, but will monitor to see if this comes to fruition.

Austin/Hampshire

Diagnosing Storm Growth Using Flash Extent Density

With convective initiation underway, we assess the intensification of thunderstorm updrafts using PGLM Flash Extent Density to determine electrical activity within the storm. The cell below has shown several weak lighting pulses over the last 15 minutes and is showing signs of becoming severe. Reflectivity is on the rise and the lightning activity appears to be foretelling of possible storm severity quite well.

Two panel of Flash Extent Density (left) and composite reflectivity (right)

Pseudo-GLM use from May 7th

Yesterday we had the opportunity to view the PGLM data southeast of Lubbock, Texas courtesy of the West Texas Lightning Mapping Array.  The results were interesting.  At past Experimental Warning Programs, we have seen flash extent densities of over 80 flashes for the Oklahoma LMA which updates every minute.  However, yesterday, the PGLM maxed out at 41 flashes for the storms that developed.  This was less than we had expected, based on previous years with one minute data.  The environment was interesting as these were elevated thunderstorms.

Although lower than viewed in the past, this maximum did precede the full development of the storms, although storm reports are hard to come by as this is a low population region.  Overall, this was a good dry run for today (May 8th) as we will be active in the western portions of the Oklahoma LMA today and will have the chance to fully try out the PGLM observations and the lightning tracking tool.

The PGLM observations at 2312 UTC showing a maximum flash extent density of 35 flashes (blue grid box).

The corresponding radar reflectivities from the Lubbock radar at 2321 UTC.  Note that the PGLM was greatest with the core of the main storm.