Topic: Significant severe weather in store for Eastern states.

[Mike]

I listened with interest to Jimmy's response to a question by the host on A Current Affair re if NSW due for a significant severe storm outbreak in the near future and Jimmy confirmed that he expected something on the horizon.

Perhaps, Jimmy you could elaborate further on the observations you have seen of previous years and what you believe makes the upcoming storm season or beyond more significant in terms of weather expectations?

Mike

[Jimmy Deguara]

Mike,

My response is due to trying to give an impression I satisifed why I was there - ie re "superstorms". Of course I never gave any mension to the "superstorm" but I did suggest we will get hailstorms this season. But I guess we do get hailstorms every season. This season could be thr turn around because of generally increased moisture availability and one would think that this should increase the likelhood of thunderstorms and hailstorms given the correct conditions.

We are experiencing a fairly cold pattern as well as cold maximum temperatures overall this season. With colder air aloft, the transition into spring and summer could make things interesting - well hopefully. The law of averages certainly have not been for favouable severe storms we seemed to have many years back. I guess the last serious hailstorm in Sydney was April 1999 - over 8 years ago! We are overdue in my opinion.

Regards,

Jimmy Deguara

[Mike]

And would it be fair to say that La Nina this time around would enhance the chances of very severe weather?  Seems this year was pretty intense from the posts of the past, I didn't think it could get any better, but having said that you have mentioned before that 2007 was a bit lax in the way of regular storm activity.  I think most chasers in NSW would be glad to see el Nino go for a long while!

Mike

[Jimmy Deguara]

Well Mike comparing the intensity and frequency of severe weather is a bit tricky. Do you consider that perhaps some areas had an awesome season as compared to other areas that seemed to miss out overall. Sydney on the one hand has not had what I call a good severe storm season since the 2004 / 2005 summer and particularly in early 2005 but some activity in November 2004. Also, sometimes one or two major events can dominate almost an entire season if not thought about carefully. For instance, 1996/1997 season produced 3 distasters in one season (including the 3 tornadoes on 29th September and December 11th Singleton hailstorm) in an otherwise poor season.

David and I often refer to the mid to late 1980's as prime time for Sydney. There were some reasonably savage severe storm events including a reasonable frequency of severe weather for the region. Overall, if you chase storms, most of the time you place yourself in a position to enjoy those areas experiencing that better season or at least episode.

Talking about La Nina and El Nino, I don't think either extremes are the best for severe storms in eastern Australia although La Nina is far better than El Nina simply because of the availability of moisture. My preference is an intermediate year with near neutral conditions though I have no scientific basis to make such claims - just through observation.

I guess time will tell.

Regards,

Jimmy Deguara

[Mike]

Ironic that you mentioned neutral periods as here it was the opposite so far as whether some areas miss out.

 Some areas no doubt received severe storms more than other areas and with the change of El Nino and La Nina cyles that would certainly have an effect wideranging.  As far as chasing these bigger storms, it's really in the lap of the Gods so to speak but no doubt bigger things are on the horizon.  You've seen 'quiet times' in the US and then the year after it goes berserk.  I agree with you on all accounts.


Mike

[Jimmy Deguara]

 
Just to clarify my reasoning, La Nina is best for producing heavy rainfall events rather than the atypical severe hailstorms. I prefer intermediate years as they bring forth a mix of drier air and moist air as well as troughs positioned in NSW. La Nina tends to encourage more inland extreme western NSW and SA troughs as well as heavy rainfalls and flooding over the inland not the most ideal potent severe storm producers. El Nino tends to encourage drier air too close to the coastline, bushfire weather and drought conditions overall.

This may be general, but you will find that a similar scenario of the effects on the dryline is now being accepted to exist in the US in Tornado Alley. The dryline is more prone to advancing more rapidly during the drier years than during the moist years. This encourages a more favourable dry line setup including classic tornadic supercells. The excess heating also can impact the cap given the warmer air in New Mexico overrides the moist air near the dryline. The end result is higher based and less potent dryline storms.

Regards,

Jimmy Deguara

[Mike]

Thanks, that explains a lot especially with the differences in both cycles when considering the affects of them also in that part of the country.  The cycles certainly have an impact on weather as we have seen this year with drought and then flooding.

Mike

[Mike]

As a result of the coverage on national TV have you had feedback from the private sector or weather enthusiasts in general on what was shown?  I know there was a lot of talk about it up here with my workmates re severe weather in NSW of late and they were interested in finding out more - which is always healthy for discussions!

Mike

[Jimmy Deguara]

Hi Mike,

Despite my attempt to distance myself from the "superstorm" term, obviously the media's manipulation certainly won. I guess though it may not be such a bad thing as it may raise people's curiosity and awareness. We'll see. Certainly an effective interview in terms of public reaction.

Regards,

Jimmy Deguara