Daily Debrief (for activities on 05/06)

Forecasters operated in Cheyenne and Norman. Sim Sat Imagery was not working. Norman LMA was not working.

GOES-R CI:
- It didn't do so well in the west
- would be much more useful with rapid scan rather then waiting 15 minutes
- A lot happens with storms between a 15 minute scan
- There was a 90% prob on a storm that subsequently matured
- It didn't do so well with earlier elevated convection. Later when stuff was more surface based, it did a little better

NearCast:
- Area of high instability in northern Wyoming. The storms moved right along the instability axis and continued to be strong
- Storms in Texas developed within the axis of greatest instability

Prob Severe Model:
- I like the display. It is a good concept for situational awareness. I warned on a storm totally based on its probability (60%). It later weakened and split, one of which became severe.
- It should be used as: here is the current environment, this is what is going on with this storm
- No one has done a lot with probability of severe wind, estimating wind gust, etc. So that would be something nice to see


-- Bill Line, SPC/HWT Satellite Liaison

Strong storms over north central Texas

The NOAA/CIMSS ProbSevere model indicated probabilities into the 70-80% range with storms developing along the dryline in the vicinity of Abilene and Wichita Falls, Texas.  Figure 1 shows an example of the NOAA/CIMSS ProbSevere output overlaid on KFRD 0.5 degree reflectivity at 0008 UTC 7 May 2014.

Figure 1.  NOAA/CIMSS ProbSevere output and KFDR 0.5 degree reflectivity valid at 0008 UTC 7 May 2014.

No severe reports nor warnings have been associated with these storms, so these count toward the false alarms for today.  The following question was posed to the NWS forecaster assessing the ProbSevere data over this region:  "Are you troubled by the relatively high ProbSevere values with these storms?", and he replied:

"Definitely not!  I would expect high probabilities based on my analysis of all radar tilts.  There was over 60dBZ reflectivity to near 20,000 feet and 55 dBZ to near 30,000 feet.  I wouldn't be surprised if these storms did produce severe hail, but they were in a very sparsely populated portion of Texas.  Perhaps the high freezing levels, which I estimate to be near 13,000 feet and surface temperatures near 100F may also have contributed to partial melting of hail falling from these storms.  We noticed hail spikes in the radar reflectivity imagery."

We are planning on investigating the value of including freezing level information within the NOAA/CIMSS ProbSevere model, among other NWP fields in the future.  Freezing level information may have been useful in this case.

-Sieglaff

GOES-R CI in Texas

GOES-R CI showed 60-70% probabilities east of Abiline at 2200 UTC. By 2230 UTC these cloud objects had developed into mature convection.

ProbSevere and All Tilts Usage

Just a note related to ProbSevere and All Radar Tilts usage within AWIPS-II.

A user noticed temporal and radar tilt looping behavior while ProbSevere was loaded with 'Time Match Basis' did work as expected.  As such it is important users load all radar tilts and may load ProbSevere, but do NOT do 'Time Match Basis' for ProbSevere when using all tilts.  It might be good practice to also load ProbSevere model output atop 0.5 degree reflectivity and/or MRMS reflectivity with Time Match Basis set to ProbSevere to ensure all ProbSevere updates are receieved.

-Sieglaff

60+ dBz has entered the OUN CWA just after 00Z

At 00:08Z, the northernmost storm just ahead of the dry line has just entered the OUN CWA. Prob severe was sitting at 66% with estimated hail size of just under an inch.

Scott Rudge

a cool radar image…

It’s the evil “inverted bow echo”.  Actually a storm splitting just north of CYS 23:48Z

Update 00:30Z  looking at total lightning along this storm…the following image represents total ltg. at the time of the above image.  Lightning dropped off quickly shortly after…at the same time the storm weakened as it went through a split/reorganization.  By 00:15 ltg had picked back up as the storm reorganized.  Storm as strong as it has been at 00:30 (74% on ProbSevere, 1.10″ MRMS MESH) but lightning as not picked back up to its previous high levels before the previous split…

Experimental warning KCYS

A strong thunderstorm developed near Cheyenne, Wyoming late Tuesday afternoon.  The forecasters at EWP have grown more comfortable using the NOAA/CIMSS ProbSevere output and noticed at 2330 UTC 6 May 2014 the probabilities jumped to 66%.  The ProbSevere information combined with radar appearance caused the EWP forecaster to issue an experimental severe thunderstorm warning at 2331 UTC 6 May 2014 (Figure 1).

Figure 1. NOAA/CIMSS ProbSevere model, KCYS 0.5 degree reflectivity, and EWP experimental warnings valid 2330/2331 UTC 6 May 2014.

This storm proceeded to split and weaken for a time, but then began to reorganize.  The ProbSevere output again increased to 64% at 0010 UTC 7 May 2014 (Figure 2) and 74% at 0026 UTC 7 May 2014 (Figure 3).

Figure 2. NOAA/CIMSS ProbSevere and MRMS composite reflectivity at 0010 UTC 7 May 2014.

Figure 3.  NOAA/CIMSS ProbSevere and MRMS composite reflectivity at 0026 UTC 7 May 2014.

The Cheyenne NWS office issued a severe thunderstorm warning on this storm at 0030 UTC 7 May 2014.  Should any reports be received, we will post them here.

-Sieglaff

Prob Severe Model Output

All output of Prob severe model are white text.  Change font/color based on certain thresholds. For example, MESH output changes to yellow once 1 inch hail is predicted etc.

Bruce T.

Nearcast…Texas Convection

Convective initiation has once again lined up pretty well with the instability depicted on the theta-e difference graphic in the nearcast. I have now seen this in a couple of cases. The nearcast forecast brings some instability north into Oklahoma later this evening. It will be interesting to see how this lines up with the convection at that time, as the HRRR model has shown some decent development across portions of North Central Texas and Southwestern Oklahoma.

Jared Maples

Finally, SE WY?

2200Z…KCYS showing a few showers developing.  Vis satellite shows these cells developing just out ahead of a deck of cirrus to the west.  Instability seems marginal, at best, in this area based on Nearcast analysis.  Northern cells are closer to better instability.

Meanwhile, earlier strong storms moving NE out of central WY held some strength likely at just sub-severe levels…and have weakened further.  Will monitor as these cells again are in the area of greater instability.