TWO storms by 6/30: statistical implications for 7/1+

[LarryWx]

I counted 13 seasons since 1851 in which there were 2+ storms by 6/30, which is about one every twelve years. The average number of 7/1+ storms for these 13 seasons was EIGHT. The average number of 7/1+ storms for all seasons back to 1851 is ~EIGHT. So, this tells me that having had two storms by 6/30 is itself pretty much a NEUTRAL indicator for the period 7/1+ alone.

Regardless, as Perry suggested, the highest # of 7/1+ storms for these 13 seasons was 19 (in 1933), followed by 13 (in 1936). However, the lowest # of 7/1+ storms was 3 (in 1902), followed by 4 (in 1986). So, the statistics suggest quite a large spread of possibilities.

[Swimdude]

We're not having 5 storms this season, or i'm going on strike in 2006.

[MWatkins]

I counted 13 seasons since 1851 in which there were 2+ storms by 6/30, which is about one every twelve years. The average number of 7/1+ storms for these 13 seasons was EIGHT. The average number of 7/1+ storms for all seasons back to 1851 is ~EIGHT. So, this tells me that having had two storms by 6/30 is itself pretty much a NEUTRAL indicator for the period 7/1+ alone.

Regardless, as Perry suggested, the highest # of 7/1+ storms for these 13 seasons was 19 (in 1933), followed by 13 (in 1936). However, the lowest # of 7/1+ storms was 3 (in 1902), followed by 4 (in 1986). So, the statistics suggest quite a large spread of possibilities.

Good point. However...I believe the years that usually feature 2 storms in June do so as a result of a front hanging around in the tropics (not unlike 1997), which generally indicate conditions that would not be favorable for systems getting out of the MDR later on.

However, this season already has featured 1 purely tropical system (Bret) and a mostly tropical system (Arlene) that have both been pulled out of the Caribbean...and not from a frontal boundary.

Regardless of climo...I believe the following overrides any argument of a quiet season or even normal season...



Look south of 30N. Hard to find a spot that isn't atleast 1C above normal.

You are right on...I think...with the argument that 2 storms in June doesn't mean much. But if you compare the origin of those 2 storms...and the SST's out there...and with no Nino...well...that probably doesn't fit into the previous set-ups.

MW

[mobilebay]

I counted 13 seasons since 1851 in which there were 2+ storms by 6/30, which is about one every twelve years. The average number of 7/1+ storms for these 13 seasons was EIGHT. The average number of 7/1+ storms for all seasons back to 1851 is ~EIGHT. So, this tells me that having had two storms by 6/30 is itself pretty much a NEUTRAL indicator for the period 7/1+ alone.

Regardless, as Perry suggested, the highest # of 7/1+ storms for these 13 seasons was 19 (in 1933), followed by 13 (in 1936). However, the lowest # of 7/1+ storms was 3 (in 1902), followed by 4 (in 1986). So, the statistics suggest quite a large spread of possibilities.

Good point. However...I believe the years that usually feature 2 storms in June do so as a result of a front hanging around in the tropics (not unlike 1997), which generally indicate conditions that would not be favorable for systems getting out of the MDR later on.

However, this season already has featured 1 purely tropical system (Bret) and a mostly tropical system (Arlene) that have both been pulled out of the Caribbean...and not from a frontal boundary.

Regardless of climo...I believe the following overrides any argument of a quiet season or even normal season...



Look south of 30N. Hard to find a spot that isn't atleast 1C above normal.

You are right on...I think...with the argument that 2 storms in June doesn't mean much. But if you compare the origin of those 2 storms...and the SST's out there...and with no Nino...well...that probably doesn't fit into the previous set-ups.

MW

It is my belief that with these early storms and the current set-up for the heart of the season, we could easily equal or surpass 1995 numbers. JMHO

[LarryWx]

Good point. However...I believe the years that usually feature 2 storms in June do so as a result of a front hanging around in the tropics (not unlike 1997), which generally indicate conditions that would not be favorable for systems getting out of the MDR later on.

However, this season already has featured 1 purely tropical system (Bret) and a mostly tropical system (Arlene) that have both been pulled out of the Caribbean...and not from a frontal boundary.

Look south of 30N. Hard to find a spot that isn't atleast 1C above normal.

You are right on...I think...with the argument that 2 storms in June doesn't mean much. But if you compare the origin of those 2 storms...and the SST's out there...and with no Nino...well...that probably doesn't fit into the previous set-ups.

MW

Thanks Mike, Nice post. I pretty much agree with you, which puts more weight than normal on the two most active of the 13, 1933 and 1936.

[Matt-hurricanewatcher]

Has there ever been a hurricane season that the 26c line reached 45 north at 70 west??? Or even 60?

[dhweather]

Each season is different - there are similar years with similar climatology
and anologs - but they are just that - similar.

For example, Dr. Grey used 2003 and 2004 as analogs for his 2005
forecast.

There's a lot of difference in those two seasons alone. Just ask Florida.

As for two named storms in June, well, it is the season, and I personally
don't believe that is an indicator of how the 2005 season will proceed.

[Derek Ortt]

one thing that cannot be predicted are the SAL outbreaks. There is no way of knowing as to whether or not the SAL will take a vacation like it did last year, or if it will be in force as it has been in the past

[MGC]

I would be reluctant to use data prior to the satellite era. Many fish storms were missed. Plus, the Atlantic is in the warm phase. I think we will see a above average number of named systems.....MGC

[rainstorm]

it was pointed out on another board there is very little relationship between above normal atlantic sst's and num of storms

[MWatkins]

it was pointed out on another board there is very little relationship between above normal atlantic sst's and num of storms

Although, as an independant variable all by itself, SST's in and of themselves may not represent a link to increased storm frequency during most years, where SST's are running slightly or even moderately above normal.

However, there is a link between SSTs and increased major hurricane frequency even in those seasons. But this season, at least so far is much much different.

This year, SST's aren't running slightly above normal in some areas. They are running above normal at record rates throughout the entire tropical development region south of 30N.

I suppose what it comes down to is who do you believe? I personally will take the thoughts of Dr Gray here, who has been studying these things over 50 years, over someone using some nickname on some other weather board.

Dr Gray is quoted in his most recent June 1 outlook:

The reader will note that we have raised our forecast considerably from what the statistics would indicate. This is due to the fact that we are in a new active era for Atlantic major hurricane activity, and Atlantic SST conditions are close to being the highest on record. We believe these unusually warm Atlantic SST conditions are high enough this year that they will trump most of our usual seasonal statistical predictors shown in Table 1.

I'm gonna stick with Dr Gray here...

MW