High Helicity / Low CAPE Severe Wx Environments?
Posted: Thu Dec 17, 2009 11:52 am
Hi all,
Some technical research flavored questions to ponder...
While reading this morning's NWS Melbourne AFD I noted that the overnight forecast team's AFD mentions Friday Dec. 18th's set-up as exhibiting "a classic high helicity/low cape tstm environment." I've not seen this exact phrasing used before and was wondering what is meant by "classic" in this case?
Two additional questions:
1) Have there been any systematic studies of Florida severe weather environments with a specific focus on the relationship between CAPE and other factors? In my recollection, it seems that many events exhibit marginal instability and yet still produce significant severe weather (e.g. tornado outbreaks of 12/25/06 and 02/02/07).
2) While searching for information on the high helicity/low CAPE environment, I noted a website by storm chaser Jon Davies who worked with some NWS forecasters to examine such an environment. Davies makes the conclusion that forecasting low CAPE tornado environments might be enhanced by "development of CAPE/shear products that might highlight 'small CAPE/large shear' environments favorably distributed in the vertical for tornadoes (e.g., parameters combining low-level shear and CAPE below 3-5 km above ground?)." -- Has such a product been yet developed? Davies case study is from 2004.
Many thanks to any who can offer some insights or answer any of these questions!
- Jay
South Florida
Some technical research flavored questions to ponder...
While reading this morning's NWS Melbourne AFD I noted that the overnight forecast team's AFD mentions Friday Dec. 18th's set-up as exhibiting "a classic high helicity/low cape tstm environment." I've not seen this exact phrasing used before and was wondering what is meant by "classic" in this case?
Two additional questions:
1) Have there been any systematic studies of Florida severe weather environments with a specific focus on the relationship between CAPE and other factors? In my recollection, it seems that many events exhibit marginal instability and yet still produce significant severe weather (e.g. tornado outbreaks of 12/25/06 and 02/02/07).
2) While searching for information on the high helicity/low CAPE environment, I noted a website by storm chaser Jon Davies who worked with some NWS forecasters to examine such an environment. Davies makes the conclusion that forecasting low CAPE tornado environments might be enhanced by "development of CAPE/shear products that might highlight 'small CAPE/large shear' environments favorably distributed in the vertical for tornadoes (e.g., parameters combining low-level shear and CAPE below 3-5 km above ground?)." -- Has such a product been yet developed? Davies case study is from 2004.
Many thanks to any who can offer some insights or answer any of these questions!
- Jay
South Florida