Issued: Tuesday, June 1, 2010 440 am EDT/340 am CDT
This is an updated seasonal forecast and is being updated to increase the number of expected storms and to also try to pin down the areas that are of greatest risk this hurricane season.
Bottom line, it looks like we are in for one hell of a bad hurricane season. I cannot stress this enough!!
ENSO Conditions: The strong El Niño that was observed this past winter has all but disappeared and has been replaced by neutral conditions. It appears that La Nina conditions will develop during the summer and in fact, La Nina conditions may already be developing across the Atlantic Basin.
The current sunspot cycle is something that needs to be looked at as well. Low levels of sunspot activity (like what is occurring right now) is accompanied by a decrease in solar wind activity. There is theory out there that says low sunspot activity is correlated with cloud growth and thus help lower the sea level pressures and favor a cooler ENSO (ie. La Nina).
So, based on this it appears that we are well into neutral ENSO conditions and a La Nina appears to be developing. This La Nina is forecast to become moderate as the hurricane season progresses. La Nina conditions support low sea level pressures and low wind shear values over the Atlantic Basin. This will likely enhance tropical cyclone activity in the Atlantic Basin.
Atlantic Multidecadal Oscillation (AMO): The AMO is basically a long term pattern of variability in sea surface temperatures in the Atlantic Basin. This strongly influences tropical cyclone activity by modifiying sea surface temperatures over the Atlantic.
The AMO is currently warmer than it has been in recent history. The latest monthly AMO value was 0.478°C, which is the fourth warmest value in any month on record. More important to tropical cyclone activity, however, are sea surface temperatures in the tropical Atlantic. Readings in this area are measured by the Tropical North Atlantic (TNA) index. The TNA dataset only goes back to 1950. With that said, both March and April’s values are new records and sea surface temperatures have only increased further during May.
The reason why sea surface temperatures are so warm is because an unusually weak subtropical ridge of high pressure was in place over the tropical Atlantic. This, in turn, reduced trade winds in the tropics and helped to warm the sea surface temperatures.
As we head into the hurricane season, I expect that the easterly ocean currents over the tropical Atlantic will carry the very warm sea surface temperatures westward and cause the Caribbean and Gulf of Mexico to warm further than what has already occurred. Based on this, I expect above to well above average sea surface temperatures in the Caribbean and Gulf of Mexico by the heart of the hurricane season. These very warm sea surface temperatures across the entire tropical Atlantic will be very favorable for tropical cyclone formation since they cause lower sea level pressures and thus causes more convection and fuel for developing tropical cyclones.
Analog Years: I have tried to focus in on just a few years that are a close match to what this hurricane season may be like. They are 1964, 1969, 1995 and 2005. As for potential risk areas, I have attached links that outline each hurricane season of those 4 analog years. A few areas stand out for higher concentration of landfalls during those 4 analog seasons. These areas include eastern North Carolina and the outer banks of North Carolina, south Florida and the northwest Bahamas, the central Gulf coast (from Louisiana to the Florida Panhandle), the Leeward Islands and Virgin Islands and finally the northwest Caribbean, including the Yucatan Peninsula, western Cuba and the Cayman Islands.
This idea for potential threat areas is supported by the forecast summer pattern of a ridge of high pressure over the southeastern United States. This ridge of high pressure will prevent any tropical cyclones from turning out into the open Atlantic once they reach 65 West Longitude and potentially steer these storms right into the Gulf of Mexico.
Highest Threat Areas For 2010 Hurricane Season:
Based on the very favorable conditions out there this season, I am increasing my projected number of storms/hurricanes/major hurricanes for this year:
18 Named Storms
6 Major Hurricanes
One caveat to my forecast number of storms and hurricanes is that if the wind shear values end up being more favorable for tropical cyclone development and the dry Saharan dust layer is less pronounced than what is being forecast (which both are already forecast to be fairly low during the hurricane season), we may end up with storm numbers in the twenties and may in fact approach the levels seen in 2005.
Sea Surface Temperature Map:
Tropical Cyclone Heat Potential Map:
So, to sum it up, I am looking at a hurricane season coming up that will be extremely active. I expect La Nina conditions throughout the hurricane season. In addition, above average to much above average ocean temperatures and below average sea level pressures point to a potentially extremely active hurricane season with at least two landfalling tropical storms and at least three landfalling hurricanes on the US coastline.
This outlook should be the catalyst to really buckle down and purchase supplies for the hurricane season. A really good website to help you create a plan for the hurricane season is http://www.onestorm.com .
If you haven’t done so already, put together your hurricane survival kit as soon as possible. In addition, please take a close look at your homeowners or renters insurance and ensure that you are properly covered for damages or total loss. Also, if you don’t have flood insurance and live in a hurricane zone, I strongly urge you to consider taking on flood insurance. Your homeowners/renters insurance does not cover for floods caused by storm surge or river flooding and it takes 30 days for the flood insurance to take effect.
2010 Atlantic Tropical Cyclone Names: