Archive Cases Ending…Prob Warn Training to Begin

Our teams are filling out PAR and CASA evaluations following their archived events.

Kevin/Eric discussed how to best display CASA data. They would like to be able to easily choose one radar and tilt up to higher elevation. They like the utility of CASA at low levels for wind/tornado threat without much thought to hail threat.

Yesterday…they were hanging on every 1-minute update with PAR, looking intently for changes in storm character. They did not experience the same type of anticipation with CASA today. This could be related to the case selection. Some positives they point out are the fine spatial resolution and near ground sampling.

With both PAR and CASA, Kevin sees need for substantial training to avoid dramatic increase in false alarm rate. These small scale signatures and short-lived shear couplets or RFDs have always been out there. Now that we can see them, it doesn’t necessarily mean we should be warning for each of them.

Brad/Eric are discussing when additional information becomes too much. “Rarely would a meteorologist decline more information, but in some cases it just becomes more on the floor (or tossed aside).”

All forecasters are moving to a seminar room for training on Probabilistic Warnings from 2045-2130 UTC.

Patrick Burke (EWP Weekly Coordinator, 27-30 May)

Storms in western Oklahoma have either weakened or moved southward to very long range from central Oklahoma radars. Today’s severe potential is largely driven by the diurnal cycle, and there is little hope of additional activity; the MCS outflow from this morning simply proved too deep and widespread across central Oklahoma. The event did provide Eric and Kevin a chance to become familiar with PAR data, and they will continue that theme by working an archived event this evening.

Meanwhile, Brad and Mark are viewing archived CASA data to increase their comfort level with the look and feel of that data. Between 2330 UTC and 0130 UTC they plan to run through another event in real-time playback to evaluate the utility of CASA data in making warning decisions.

Patrick Burke (EWP Weekly Coordinator, 27-30 May)

PAR Temporal Resolution Discussion…

Eric & Kevin are working the Altus storm… and their first look at PAR and 88D side by side has sparked discussion of the differences in resolution and sampling techniques. Kevin would like to see enhanced azimuthal resolution (lower beam width) for PAR in the future. Kevin remarks that the 1-minute update has made it easier to pick up on new cell development along the storm’s rear outflow flank. The forecasters earlier observed a supercell split on the Elk City storm…and felt the rapid updates were beneficial to seeing this.

Eric has another interesting perspective. He thinks the 1-minute resolution might be “annoying” early in an event when you don’t yet have a particular severe weather threat or focus. It may be overwhelming to process so much data. Maybe we should apply the forecast funnel to this… and be able to choose when to switch from 5 or 10 minute resolution down to the 1-minute resolution as needed.

Patrick Burke (EWP Weekly Coordinator, 27-30 May)

PAR operations underway…

Kevin and Eric will begin Phased-Array operations centered on the Altus, OK, supercell. Mark and Brad will practice interrogating WSR-88D data using WDSSII while being on standby for either CASA operations or a CASA archive case later this evening.

Patrick Burke (EWP Weekly Coordinator, 27-30 May)

Western OK…IOP begins 5 PM

Forecasters completed PAR and CASA Training, and are now learning WDSSII using live data of a supercell near Altus, OK. There is a second severe storm near Elk City. Both storms are moving very slowly…seemingly balanced by southeasterly low level inflow and southwesterly mid level steering flow. They may also tend to propagate into the instability axis…which is unfortunately just west of the CASA network. With some luck, however, we could see storms reach the western parts of CASA later this evening. PAR operations will begin at 5 pm.

Patrick Burke (EWP Weekly Coordinator, 27-30 May)

Training Continues…3pm

The SPC has placed southwest Oklahoma, including most of the CASA domain, under a Severe Thunderstorm Watch until 03 UTC. The outflow boundary has zipped up with a pre-frontal trough from Shattuck to Mangum, OK. Scattered CBs have formed off and on in this zone…but none have quite taken hold, as convergence and lift remain quite shallow. Other thunderstorms have begun to sustain themselves farther south along the trough axis into Texas. Opportunity for more robust convective initiation should increase up into Oklahoma with additional heating/destabilization. Water vapor imagery also hints at the influence of a short wave ridge exiting western Oklahoma…with a more diffluent upper flow pattern approaching from eastern New Mexico/West Texas.

The forecaster/evaluators have switched places so that both sets of two will receive training on both the PAR and CASA experiments. The Oklahoma IOP will either begin at 4pm (WDSS training on the fly) or 5 pm (WDSS traning at 4pm).

Patrick Burke (EWP Weekly Coordinator, 27-30 May)

Calling a wrap on operations w/ ongoing storm in Dewey/Custer Co. so forecasters can do the PAR survey. SHAVE has some 3 inch hail reports from this cell.

SAD Observation: Some lady just won a bunch of money on Deal Or No Deal!

Travis Smith (EWP Weekly Coordinator, 19-23 May)

Call to chasers Greg Stumpf and Jim LaDue confirms that storm is outflow-dominant, still a very HP-looking supercell.

Travis Smith (EWP Weekly Coordinator, 19-23 May)

Forecasters are issuing PAR-based warnings using the Prob Warning tool. The way to interpret the data is that they are encircling the storms of interest with the polygon tool and selecting either “Severe Thunderstorm” or “tornado” warning.

Dealiasing is an issue, but not just on the PAR.

Storm is moving into higher dew point air.

Travis Smith (EWP Weekly Coordinator, 19-23 May)

Low HWT staffing today, so Live Blogging is slow…

PAR IOP is up, with all forecasters participating. SteveH is also doing Prob Warn.

Gate-to-gate right now has good continuity that cannot be seen in the KTLX velocity data.

Travis Smith (EWP Weekly Coordinator, 19-23 May)