Very large hail in non-supercell storms?

[Menno van der Haven]

At 6 june 1998 a severe hailstorm produced hailstones with a diameter of 6-7 cm (2.4-2.8 inch) and a lot of damage, 15 miles E-SE of Rotterdam, The Netherlands.
Although I observed wallcloud-like structures and a long smooth inflow-tail of that storm during a chase, at that moment radar showed a line of storms with no clear sign of a supercell. The large hailproducer was on the southern tail-end of the line and was probably a hybrid-kind of multicell-supercell at that time.
(About one hour later the storm started right-moving and produced even larger hailstones of 8-9 cm (3.2-3.6 inch) and also spawned a brief tornado near the city of Zwolle. It clearly was a supercell by then).


When the diameter of the largest hailstones in a storm are 2 inches or larger, it is often defined as a very large hail (or significant hail)-event. In the scientific literature it is made clear that such an event is very likely to be associated with supercell storms.

My question is: Is it possible that non-supercells (mainly of the multicell or pulse-severe type) produce very large hail? Or is it, in such a case, a multicell-supercell hybrid and not a 'true' multicell ?

 

[rdale]

Not possible in pulse storms, but I wouldn't rule out 2" in non-rotating thunderstorms... However I'd think to get much larger than that would require a sup.

 

[cdcollura]

Good day,

I have seen hail over 2" in MULTICELL CLUSTER storms (non-rotating and non supercellular).

 

[Doug Lee]

The main feature of a storm that determines hail size is the updraft. It needs to be strong enough and persistent enough to keep the hail aloft long enough to grow to significant size. I could see that happening with a strong, long-lived multicell.

 

[Kiel Ortega]

Good day,

I have seen hail over 2" in MULTICELL CLUSTER storms (non-rotating and non supercellular).

I'm curious to know exact cases where this has occured. From what I have seen with my research, cluster (-ed) storms tend to have smaller hail than the supercells/more discrete storms. I've discussed this with Arthur Witt and our discussions led to seeding of the storms by other storms => many more nuclei for hail => more hail stones but of smaller size due to LWC restrictions (?). I put the question mark because who the hell knows in the end.

Anyways, I'd love to know of non-supercell/clustered storms producing sig. hail...make a really good comparison with discrete/supercell storms.

 

[Menno van der Haven]

The main feature of a storm that determines hail size is the updraft. It needs to be strong enough and persistent enough to keep the hail aloft long enough to grow to significant size. I could see that happening with a strong, long-lived multicell.

That's also what I've been thinking.
For a storm to produce very large hailstones (>= 2 inch) a strong updraft is needed to keep hailstones 'floating' for a long time to collect supercooled droplets at the surface of the hailstone (air temperatures between -10C to -30C are most favourable). However, if the residence-time of a hailstone in a multicell-updraft is relatively short, say 15 to 20 minutes, it cannot grow that large.....
....unless the hailstone falls into another updraft where it can undergo the growing process further. But I believe that scientists have left the idea of falling into fresh updrafts???

In fact, when you closely look at the updraft of a supercell storm, (besides the very important difference of rotation) it resembles a multicell storm, but with a very short pulse-interval.

 

[Oscar van der Velde]

http://weather.uwyo.edu/cgi-bin/sou...AR=2007&MONTH=05&FROM=2212&TO=2212&STNM=10393
This sounding has yielded several hail reports >2 cm scattered over southeastern Germany and even 5 cm measured stones in Brandenburg, eastern Germany Tuesday. As you can see there is almost no shear and not any special CAPE. Storms were mostly single cells but some clustered together in a zone of deep convergence. I doubt there were any supercells.
This raises the question which signals one can possibly use to forecast it, if such minimal environments can cause such events?! "Any MLCAPE above 500 J/kg and persistent convergence" may be a valid, but maybe not very satisfactory answer.

Oscar