Kevin M. blogging abouy Bryan and Crag’s PROBWARN experience. Quick synopsis – we are focused on the LBB area. Currently there is little/no TOR threat, so we’re warning on hail.

A few quick questions have already arisen: (since we are currently issuing low-prob warnings)

[Why] would we bother with low prob warnings in a higher end situation?

How best to approach a line of pulse severe? [Do we encompass the line and then issue individual smaller ellipsoids within the line? Decided against – too much work to keep track of all of those indivisual warnings.]

Apprehension to issue many small warnings instead or within the larger one. Mainly a workload issue. Also, these are low-prob warnings.

How do we split a warning into 2 warnings/ Keep and existing one and make a new one? Delete the existing and creat two new ones?

Quick little couplette appears SE of LBB. Do we consider an environmental change and start considering issuing a low-prob TOR threat with these storms?

0030z – issuing a ‘high’ prob warning anticipating a storm merger NNW of KLBB.

Workload becoming an issue – having trouble issuing new warnings and keeping track of exiting warnings in a timely manner. (May be due to storm situation, or software.)

After about 2 hours of running the PROBWARN, Bryan was getting pretty fatigued. Craig switches to PROBWARN issuer at 0046z.

Trying to issue simultaneous hail and wind warnings for the same storm is difficult. (Embedding one polygon within another gets somewhat problematic either w.r.t. drawing verticies, or simply having to redraw the warning twice which takes time).

GUI issue: I have seen multiple instances of people trying to draw polygons (non-ellipsoid) and they end up drawing a straight line.

~0110z, looking at storm to SE of KLBB. Good low-level convergence. TOR prob, non-zero – considering issuing a ‘pre-TOR warning’

Calling it a night for me. been an intersting and perhaps most involved PROBWARN exercise this spring. Should be a fun debrief tomorrow.

Kevin Manross (Gridded Warning Cognizant Scientist)

Bill and Kristen didn’t pay attention to an old threat area and eventually a new storm coincidentially occupied it. They thought that new storm was the original one for which they attached the threat area. Watch out for the wagon wheel effect. This problem happened WSW of the radar.

Jim LaDue (EWP Weekly Coordinator, 5-9 May)

Craig and Brian has a bunch of overlapping polygons. They think it looks completely confusing. Craig is removing the threat areas that are in the middle of the NW and SE most areas as the storms weaken over an expanding cold pool. The storms are enhancing on the cold pool perimeter on the NW and SE sides.There still is one multicell on the ENE side of the cold pool for which Craig is retaining one original threat area. Is it better to just add a new one? Maybe but overall, the grid is the final output.

Jim LaDue (EWP Weekly Coordinator, 5-9 May)

Craig is now drafting a new hail threat area for a new ENE-WSW multicell segment that appears to have formed on an OFB southeast of LBB. There’s strong low-level convergence. Initial Hail prob=87%. Craig’s also adding an initial wind threat of 80% and kept steady.

Jim LaDue (EWP Weekly Coordinator, 5-9 May)

Brian and Craig are worried about a merger of two small multicell complexes northwest of LBB. They’re expecting brief intensification. Brian combined two swaths with initial 90 then continued 90 for an hour.

Brian’s experiencing cognitive fatigue. Craig is taking over.

Jim LaDue (EWP Weekly Coordinator, 5-9 May)

Bill issued a high prob hail threat for the cell in southeast NM (Lea co). But the storm is splitting and Bill accounted by including a wider than normal initial swath. But he’ll add a new threat area for the left mover and retain the original swath for the right mover. Environmental parameters favor the right mover to intensify.

Jim LaDue (EWP Weekly Coordinator, 5-9 May)

Craig and Brian are having difficulties handling hail threat areas for a cluster of separate multicells that are sharing cold pool but not reflectivity areas. They could massively increase workload and issue a threat area for each storm or they could include the whole area in a perimeter. Their compromise is two threat areas southeast of LBB, the northwestern one includes a loose SW-NE orientation of a subcluster of multicells, and then another to the east more oriented east-west.

One cell in the middle of the eastern cluster had a short-lived TVS which Craig thought could’ve formed a brief tornado. But the signature disappeared before he could react. Does he issue a tor threat based on the possibility of another one? They don’t have a good conceptual model to issue a threat area for now.

Jim LaDue (EWP Weekly Coordinator, 5-9 May)

I asked Bill what he thought about the left split coming off the Ward county storm. He responded by putting out a very low probability hail swath beginning at 10% and raised it to 25% in 15 min. It’s sub-legacy warning.

Jim LaDue (EWP Weekly Coordinator, 5-9 May)

Bill and Kristen minored out the probabilities on the Upton County storm and added a new hail swath for Ward county storm to 80 %. Golfball hail was reported in the latter storm.

Jim LaDue (EWP Weekly Coordinator, 5-9 May)

Brian and Craig have large threat areas identified including the southern one that encompasses 4 different small multicells. Bill, Dave and Kristen have much smaller, higher probability swaths for their two storms. Does this reflect the workload management issue? In order to match threat area sizes, Brian and Craig would have to manage up to 5 threat areas.

Jim LaDue (EWP Weekly Coordinator, 5-9 May)