2012 Atlantic Hurricane Season General Discussions

[srainhoutx]

It’s getting to be that time of year when we begin to look ahead toward Hurricane season. I have a hunch this year will offer more Gulf activity and perhaps a bit earlier in the season as well. With La Nina transitioning slowly to a neutral regime, the lack of significant Artic shots and warmer Gulf waters along with a lack of drought feedback as we saw last year may provide a better chance of an active season locally. We will see.

[wxman57]

I'm thinking significantly less active than 2010 or 2011. Maybe 10-11 named storms vs. 19 each of the last 2 years. I do think that there may be a very good chance of an El Nino this summer.



In addition, the AMO (Atlantic Multidecadal Oscillation) may well be close to normal this year, meaning SSTs near normal. SSTs were WELL above normal for the past 2 years:



And take a look at the projected SSTs in the Tropical Pacific on the image above. That's an El Nino.

Finally, for the past 2 seasons, the Euro had been predicting well below normal pressures across the Atlantic - which resulted in increased TC development. This year, the pattern is reversed. The Euro is forecasting higher than normal pressures across the Atlantic and lower pressures across the East Pacific. That would translate into more rising air in the Pacific and sinking air in the Atlantic (less storms).



So, primary long-range parameters are all pointing toward less activity in 2012 vs. 2011 (or 2010). That doesn't mean the Gulf will be as quiet as in the past season. Remember, it only takes ONE storm to make for a very bad season.

Some "quiet" years of the past:

1957 - Audrey
1965 - Betsy
1983 - Alicia
1992 - Andrew

[srainhoutx]

lol...

[wxman57]

The new CFSv2 model which is replacing the older version 1 is much more strongly forecasting an El Nino by mid summer. It's actually in very good agreement with the GFS.



From the paper on the CFS page:
http://journals.ametsoc.org/doi/pdf/10. ... BAMS3001.1

Since the CFS version 1 implementation in 2004(Saha et al. 2006), CPC and many other users have utilized the 4-times-daily seasonal integrations for their monthly and seasonal forecast products. However, the system has many internal inconsistencies. For instance, the R2 atmospheric initial states are made with technology from the 1990s, while the atmospheric model component of CFS is from a decade
later. Thus, the initial states and forecast model are inconsistent, which is a situation that leads to loss of skill during the early part of the integrations.

One of the major goals of executing the new CFSR was to create initial states for the atmosphere, ocean, land, and sea ice that are both state of the art and as consistent as possible with the next version of the CFS version 2.

So the CFSv2 is much more state-of-the-art as far as how it’s initialized.

[wxman57]

I was studying Nino 3.4 SST anomalies to compare analog seasons for 2012. Wanted to expand the view to the year before then compare the analog seasons side-by-side. Came up with the following graphics.

First, a comparison of Phil Klotzbach's analogs 1957 and 1965. Not much of a comparison between 1956, 1964 and 2008 leading up to the analog seasons:


But when I compared 2008-2009 to 2011-2012, using the latest CFSv2 2012 predictions, I got a graphic that is almost identical to the 2008-2009 pattern for this season:


Now, Nino 3.4 anomalies are only part of the analog, but the coming season's SST pattern in the Pacific is quite close to that of 2009. We know the Euro is forecasting quite high pressures across the Atlantic this season, stemming from a persistent +NAO - meaning a stronger Bermuda high, stronger easterly trades, more upwelling resulting in cooler SSTs in the MDR. Not sure of the mean sea level pressure anomalies in 2009 (and '57, '65) compared to what is predicted for this year.

Note that 2001 is no longer an analog season. Phil had put that one in because of the possibility 2012 would be a "neutral" year. But it's looking more likely an El Nino will develop. That takes out an analog with 15 named storms, meaning the analog seasons now have 8, 6 and 9 named storms. I still think there's a very good chance 2012 will have fewer than 10 named storms, possibly with only 3-4 hurricanes and 1-2 majors.

[Katdaddy]

From this morning's Jeff Master's post at the WeatherUnderground tropical page.

First named storm in the Atlantic possible next week

Both the GFS and ECMWF models are predicting that an extratropical "cut-off" low will separate from the jet stream early next week several hundred miles east of Bermuda, and linger for several days over subtropical waters with temperatures in the 22 - 24°C range. These ocean temperatures may be warm enough to allow the storm to organize into a named subtropical storm. However, climatology argues against such an occurrence; there has been only one named April storm in the Atlantic since 1851. If a subtropical storm does form next week, it would probably not affect any land areas.

Jeff Masters

[wxman57]

May need to include 1951 as an analog season, though it may not match in terms of Atlantic SSTs or the predicted strength of the Bermuda High.

[wxman57]

TSR is actually the highest predicted numbers at 13/6/3. I don't like one of their 2 predictors - SSTs. SSTs don't correlate very well with the number of named storms in a season.

I've been doing a bit of research today with respect to ENSO and Mean Sea Level Pressure Anomaly (MSLPA) 1950-2012. The MSLPA predicted by the Euro compared with past similar seasons of MSLPA would suggest <10 named storms, 3-4 hurricanes and 0-1 majors. Quite interesting.

See:
http://home.comcast.net/~cgh57/mslpa/mslpa.html

I grabbed the MSLPA image for each year 1950-2011 and added on the Euro prediction for 2012. Going through the maps, I looked for seasons with high pressure in the Atlantic, particularly in the Gulf/Caribbean and also low pressure in the East Pac. Years similar to the 2012 prediction are:

1968, 1972, 1983, 1986, 1990, 1991, 1992, 1993 and 1997

Of those, 1972 and 1997 matched the predicted pressure anomaly in the Atlantic and Pacific the best.

1968 – 8/4/0 -> 1 US hurricane landfall north of Tampa (Gladys)
1972 – 7/3/0 -> 1 US hurricane landfall east of Panama City, FL (Agnes)
1983 – 4/3/1 -> 1 US hurricane landfall Galveston (Alicia)
1986 – 6/4/0 -> 2 US hurricane landfalls, Port Arthur (Bonnie) and NC (Charley)
*1990 – 14/8/1 -> No US landfall (questionable - not the best comparison, pressure-wise)
1991 – 8/4/2 -> No US landfall
1992 – 7/4/1 -> 1 US landfall South FL and Louisiana (Andrew)
1993 – 8/3/1 -> No US landfall
1997 – 8/3/1 -> 1 US landfall in Alabama (Danny)

Average = 7.8/4/0.8

Remove 1990 and = 7/3.5/0.7


As for any relationship between El Nino, La Nina and Neutral seasons with respect to any increased probability of a US landfalling hurricane:

El Nino
21.3% of all hurricanes hit the U.S.
11.2% of all named storms hit the U.S. as hurricanes

La Nina
21.2% of all hurricanes hit the U.S.
12.1% of all named storms hit the U.S. as hurricanes

Neutral
25.8% of all hurricanes hit the U.S.
14.9% of all named storms hit the U.S. as hurricanes

La Nina + Neutral
23.6% of all hurricanes hit the U.S.
13.5% of all named storms hit the U.S. as hurricanes

I don’t see anything there to say that the U.S. is more or less likely to be hit just because of an El Nino being present. In fact, there’s no difference at all between El Nino and La Nina. Neutral seasons had more impacts per/storms. Just looking through all the seasons, it seems like ENSO status the previous year and previous winter may have had a significant impact on the upcoming season. I.E., the strong El Ninos before 1983 and 1992 (which both counted as La Nina hurricane seasons).

The Euro is predicting quite high pressures in the Atlantic this hurricane season and low pressures in the East Pac. How did the Euro do for last year? It predicted very low pressure in the Atlantic and high pressure in the East Pac, which verified nicely. The current ENSO analogs for 2012 don’t have a MSLPA similar to what is predicted.

[texoz]

SSTs appear to be making up a lot of ground over the last couple of weeks. Would not be surprised to see forecasts raised for the season when updates are published.

[wxman57]

SSTs appear to be making up a lot of ground over the last couple of weeks. Would not be surprised to see forecasts raised for the season when updates are published.

I've done quite a bit of research regarding Atlantic SSTs and numbers of named storms and found little, if any, correlation. In fact, warm AMO seasons actually had slightly less named storms than cool AMO seasons, though not statistically significant. I did find that warm AMO seasons had about twice the number (4) of major hurricanes than cool AMO seasons. Of course, that's not looking at the mean sea level pressure anomaly for those warm seasons with higher numbers of majors. It could be that the real correlation is with MSLPA as far as majors.

Oh, and I just looked at those best-correlating seasons in terms of MSLPA to check SST anomalies and found that every one of them had cooler SSTs. I think that the reason for the cooler SSTs was the higher-than-normal pressures and resulting stronger easterly trades (more cool water upwelling in the MDR), just as the Euro is forecasting for the Atlantic this year.

[Ptarmigan]

I've done quite a bit of research regarding Atlantic SSTs and numbers of named storms and found little, if any, correlation. In fact, warm AMO seasons actually had slightly less named storms than cool AMO seasons, though not statistically significant. I did find that warm AMO seasons had about twice the number (4) of major hurricanes than cool AMO seasons. Of course, that's not looking at the mean sea level pressure anomaly for those warm seasons with higher numbers of majors. It could be that the real correlation is with MSLPA as far as majors.

Oh, and I just looked at those best-correlating seasons in terms of MSLPA to check SST anomalies and found that every one of them had cooler SSTs. I think that the reason for the cooler SSTs was the higher-than-normal pressures and resulting stronger easterly trades (more cool water upwelling in the MDR), just as the Euro is forecasting for the Atlantic this year.

I ran a correlation of AMO and hurricane season going back to 1870.

AMO Data
http://www.esrl.noaa.gov/psd/data/corre ... .long.data

I found a significant positive correlation between number of storms and warm AMO. The warmer the AMO, the more storms form, especially with hurricanes and major hurricanes. Also, the ACE is higher with warmer AMO.

[Ptarmigan]

TSR is actually the highest predicted numbers at 13/6/3. I don't like one of their 2 predictors - SSTs. SSTs don't correlate very well with the number of named storms in a season.

I've been doing a bit of research today with respect to ENSO and Mean Sea Level Pressure Anomaly (MSLPA) 1950-2012. The MSLPA predicted by the Euro compared with past similar seasons of MSLPA would suggest <10 named storms, 3-4 hurricanes and 0-1 majors. Quite interesting.

See:
http://home.comcast.net/~cgh57/mslpa/mslpa.html

I grabbed the MSLPA image for each year 1950-2011 and added on the Euro prediction for 2012. Going through the maps, I looked for seasons with high pressure in the Atlantic, particularly in the Gulf/Caribbean and also low pressure in the East Pac. Years similar to the 2012 prediction are:

1968, 1972, 1983, 1986, 1990, 1991, 1992, 1993 and 1997

Of those, 1972 and 1997 matched the predicted pressure anomaly in the Atlantic and Pacific the best.

1968 – 8/4/0 -> 1 US hurricane landfall north of Tampa (Gladys)
1972 – 7/3/0 -> 1 US hurricane landfall east of Panama City, FL (Agnes)
1983 – 4/3/1 -> 1 US hurricane landfall Galveston (Alicia)
1986 – 6/4/0 -> 2 US hurricane landfalls, Port Arthur (Bonnie) and NC (Charley)
*1990 – 14/8/1 -> No US landfall (questionable - not the best comparison, pressure-wise)
1991 – 8/4/2 -> No US landfall
1992 – 7/4/1 -> 1 US landfall South FL and Louisiana (Andrew)
1993 – 8/3/1 -> No US landfall
1997 – 8/3/1 -> 1 US landfall in Alabama (Danny)

Average = 7.8/4/0.8

Remove 1990 and = 7/3.5/0.7


As for any relationship between El Nino, La Nina and Neutral seasons with respect to any increased probability of a US landfalling hurricane:

El Nino
21.3% of all hurricanes hit the U.S.
11.2% of all named storms hit the U.S. as hurricanes

La Nina
21.2% of all hurricanes hit the U.S.
12.1% of all named storms hit the U.S. as hurricanes

Neutral
25.8% of all hurricanes hit the U.S.
14.9% of all named storms hit the U.S. as hurricanes

La Nina + Neutral
23.6% of all hurricanes hit the U.S.
13.5% of all named storms hit the U.S. as hurricanes

I don’t see anything there to say that the U.S. is more or less likely to be hit just because of an El Nino being present. In fact, there’s no difference at all between El Nino and La Nina. Neutral seasons had more impacts per/storms. Just looking through all the seasons, it seems like ENSO status the previous year and previous winter may have had a significant impact on the upcoming season. I.E., the strong El Ninos before 1983 and 1992 (which both counted as La Nina hurricane seasons).

The Euro is predicting quite high pressures in the Atlantic this hurricane season and low pressures in the East Pac. How did the Euro do for last year? It predicted very low pressure in the Atlantic and high pressure in the East Pac, which verified nicely. The current ENSO analogs for 2012 don’t have a MSLPA similar to what is predicted.

I looked at your link and noticed the area of lower July to September MSLP area is larger in 1969, 1995, 1998, 1999, 2000, 2008, and 2010 than in 2005. The area of higher July to September MSLP is larger in 1968, 1977, 1983, 1990, 1991, 1992, 1993, and 1994.

[wxman57]

One thing that you need to do when looking for trends is to add in missed storms prior to recent decades. Prior to the modern age of satellite, there were likely 2-4 missed storms per season - short-lived storms out to sea that would not have been detected by ship obs. Can't just use the best track database.

[Ptarmigan]

One thing that you need to do when looking for trends is to add in missed storms prior to recent decades. Prior to the modern age of satellite, there were likely 2-4 missed storms per season - short-lived storms out to sea that would not have been detected by ship obs. Can't just use the best track database.

I am well aware of it. I should start using data from when satellites are used to today.

[texoz]

SSTs appear to be making up a lot of ground over the last couple of weeks. Would not be surprised to see forecasts raised for the season when updates are published.

I've done quite a bit of research regarding Atlantic SSTs and numbers of named storms and found little, if any, correlation. In fact, warm AMO seasons actually had slightly less named storms than cool AMO seasons, though not statistically significant. I did find that warm AMO seasons had about twice the number (4) of major hurricanes than cool AMO seasons. Of course, that's not looking at the mean sea level pressure anomaly for those warm seasons with higher numbers of majors. It could be that the real correlation is with MSLPA as far as majors.

Oh, and I just looked at those best-correlating seasons in terms of MSLPA to check SST anomalies and found that every one of them had cooler SSTs. I think that the reason for the cooler SSTs was the higher-than-normal pressures and resulting stronger easterly trades (more cool water upwelling in the MDR), just as the Euro is forecasting for the Atlantic this year.

This is a little confusing. In the past, when the forecasts came out from the major TS research institutions they usually site warmer SST as a factor in higher numbers of predicted storms. Also, common sense would dictate that with above average SST you have more energy to tap.

[wxman57]

I see nothing to indicate increasing the numbers forecast. In fact, just the opposite. New Euro and CPC forecasts are even stronger for El Nino, plus the new Euro has even higher pressures across the Atlantic this season. Would not be suprised to see a sub-10 named storms year. HOWEVER, conditions may be most favorable for development closer in to the U.S. as opposed to wel out to sea last year and in 2010. This may increase the risk of a US landfalling hurricane, possibly a major.

[Ptarmigan]

I see nothing to indicate increasing the numbers forecast. In fact, just the opposite. New Euro and CPC forecasts are even stronger for El Nino, plus the new Euro has even higher pressures across the Atlantic this season. Would not be suprised to see a sub-10 named storms year. HOWEVER, conditions may be most favorable for development closer in to the U.S. as opposed to wel out to sea last year and in 2010. This may increase the risk of a US landfalling hurricane, possibly a major.

If we go to El Nino this year, it would be the first time since 2009. Here are years that went La Nina to El Nino since 1970.
1972
1976
1997-A weak borderline La Nina occurred in early 1997.
2006
2009

http://www.cpc.ncep.noaa.gov/products/a ... ears.shtml

They produced some of the coldest winters on record for Houston area and America.

[srainhoutx]

I see nothing to indicate increasing the numbers forecast. In fact, just the opposite. New Euro and CPC forecasts are even stronger for El Nino, plus the new Euro has even higher pressures across the Atlantic this season. Would not be suprised to see a sub-10 named storms year. HOWEVER, conditions may be most favorable for development closer in to the U.S. as opposed to wel out to sea last year and in 2010. This may increase the risk of a US landfalling hurricane, possibly a major.

I agree. The latest Eurosip forecast for June, July and August does not look all that unfavorable for some potential 'home grown' tropical troubles. It only takes 1 messy, wet Claudette (1979), Allison (2001) or even Humberto (2007) like system to make for a bad season.

[srainhoutx]

AccuWeather tropical forecast is out for 2012...

AccuWeather's 2012 Atlantic Hurricane Season forecasts 12 named tropical storms, five named hurricanes and two major hurricanes.

The 2012 hurricane forecast is near-normal for the Atlantic Basin.

Potential Impact This Year
Predicting exactly where storms will make landfall in the U.S. would be extremely difficult, but there are some indications of areas where storms may brew and coasts that may be vulnerable based on weather patterns anticipated this summer.

"Home-grown" storms in the western Atlantic and Gulf of Mexico, near the U.S. Coast, are a possibility this year.

"Fronts coming down during June and July could cause energy to break off and develop tropically," Paul Pastelok, AccuWeather.com lead long-range forecaster, said.

http://www.accuweather.com/en/features/ ... cast/64215

[srainhoutx]

There is a bit deeper convection firing in the SW Caribbean this morning with a hint of mid/upper level spin. Perhaps this will be the next area to watch for an eventual invest. We will see.