2009 Hurricane Season Quick Look
Preliminary Forecast:
2009 Season: 10-12 named storms
10 year average: 15.9 named storms
30 year average: 11.9 named storms
61 year average: 10.9 named storms
This is just a very preliminary first look at the coming hurricane season. I will release my official forecast with more details in late April when I issue my summer forecast. Right now 2 major things may be coming together to produce a season with reduced activity when compared to the last 10 seasons, at least from a numbers perspective.
1. Atlantic Ocean temperatures in the region where storms most often form have recently cooled to the lowest levels since 1994.
2. Computer models are predicting our weak La Nina will weaken to neutral status and perhaps trend towards a weak El Nino by late in the summer and early Fall during the heart of the hurricane season.
Although I have only attached the water temperature graphic from March 9th, if you were to look back at early March graphics over the past 10 years, you would see that this is the coolest we have seen the prime Atlantic breeding ground area at this time of the year since 1994. The colder than normal water temperatures do not always hold, but in checking 10 years with similar water profiles at this time of year (1986, 1994, 1957, 1974, 1976, 1989, 1975, 1972, 1985, and 1950) 7 of the 10 years saw the cooler than normal conditions in that region last into the prime hurricane season (August-October). This should definitely be noted.
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We are currently still in a weak La Nina state, which is apparent in the cooler than normal waters (blue colors) along the equator in the Pacific on the graphic. But, some computer models are showing a weak El Nino developing by late summer and early fall. If this does occur, wind shear will likely increase in the Atlantic and reduce the number of storms. It is unclear if these computer models are correct and we will have to wait and see if we begin to trend that way later this spring and into the early summer.
Now things can change around in a short time and often do. I will say that I do think the Atlantic is going to be in a cooler state than we have seen over the last several years when a very warm Atlantic helped produce hyper-activity. But it is very possible the waters will warm back to near normal or even slightly above normal levels by hurricane season. It is also very possible that La Nina or neutral conditions will hang on in the Pacific longer as well and if an El Nino were to develop it could come to late to affect the hurricane season. It is just impossible to predict these things with high accuracy at this time. BUT, this is the first time since 2002, that I have seen these two factors starting to trend this way at the same time in the early spring which leads me to have lowered expectations. Keep in mind this has absolutely no bearing on landfall ideas yet, that will be worked out when I get a better idea of what the weather pattern will be this summer.
Comments
Last summer featured an 'Atlantic El Nino' which positive torques were added to Global AAM from there. Unfortunately when the lid came off of major storm development there was Ike :>(
I wonder if North Atlantic temps will continue their slow slide cooler or if we will see a mature AMO situation where the tropics are anomalously cool and storms which do survive strengthen much farther north than climatology?
Plan B could be a benign Central Atlantic Ridge displaced far enough north that Atlantic systems ride an eastern seaboard trough out to sea....
Thanks for sharing your work!
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