Note, a DCZ is not the DCVZ!

Here’s a velocity cross section from the Four-dminesional Stormcell Investigator (FSI) of the supercell near Byers, CO perpendicular to the convergence boundary.  This is a classic Les Lemon Deep Convergence Zone, transitioning to a storm summit divergence.

Greg Stumpf, EWP2012 Operations Coordinator

With limited areas favoring severe convection, we’ve moved to TFX to the lee of the Montana Rockies. Despite somewhat limited radar coverage, 3D-Var has performed very well with the supercells ongoing across the CWA. The right-most panels in the image above depict Max updraft and accumulated max updraft. The greatest magnitudes are co-located with a tornadic supercell in Judith Basin county. 3D-Var analyses appear to work relatively well even with sparse radar coverage.

The image below (Figure 1) illustrates the potential for convective initiation, using the UAH-CI tool. The high altitude jet routes overlaid with the CI and latest satellite data show the potential impacts to aviation. I expect that the CI tool will be very useful in operations – especially at the CWSUs.

TMU is always asking about timing and location of convective development. Things become problematic when routes need to be changed at the last second as a result of developing thunderstorms. If we have more tools to provide a larger lead time, TMU personnel can plan farther in advance – which leads to saving money and time…and stress!

Agitated cumulus on visible satellite noted over Childress County.  UAH CI values currently at 53, but have been steadily increasing the last few volume scans. Outflow boundary from western Oklahoma storms continues to push southwestward.  Watching to see if storms will develop if the boundary helps initiate convection. 21Z OUN WRF now showing a second line of convection developing along the southwest boundary. Stay tuned.

Latest run of the OUN WRF….

The MRMS algorithms have done well in depicting large hail and moderate storm rotation with supercells over the marine area. The first 4-panel image above depicts a cross-section through a supercell northeast of Jacksonville. A pronounced BWER is evident and correlates well with the MESH/rotation tracks panels in the bottom image.

The above image illustrates the use of 3d-Var as a potential enhancement in warning lead time. In assessing the Maximum updraft intensity in the upper right panel, we noticed a rapid increase in the magnitude of the storm updraft. MESH at this time was generally sub-severe…but an uptick in MESH is expected as analyses show increasing upward motion on the northern edge of the line segment. As an experiment, we opted to issue a severe warning based mostly in this increase in updraft speed. In retrospect, updrafts of similar magnitude have already produced hail to the size of quarters and larger, so we’re crossing our fingers.

One thing I’ve begun to wonder is will there be a loss of SA when a forecaster sees an area of “potential development”. The image below (Figure 1) illustrates the UAH-CI in the upper-left panel, while the upper-right panel shows the UW-CTC. My concern is that someone might see a CI area in the 60-70% confidence range and lose their sense of SA as they wait for further development…and the CTC algorithm to hopefully pick up on the developing storm.The UW-CTC product is designed to only pick up on the stronger development…which could easily lead to missing weaker convection. Not only that, but if any bit of the anvil goes near another developing cell…the algorithms will not pick up the newly developing thunderstorms…could end up to missing a warning.