Colorado State University forecasters released their mid-season hurricane season forecast.
Although the new data let the number of storms mentioned decrease modestly compared to the demands of the CSU at the beginning of the year, the forecasts continue to forecast a significantly above-average season in 2021.
It’s important to emphasize that seasonal prospects are interesting, but they’re just prospects. No prognosis will or can ever be 100 percent airtight. Also, let’s not forget that it only takes a single storm to hit, or even get close, a season to be considered “bad” in a particular location.
Read long-term projections like this one with caution and be prepared no matter what they ask.
With the CSU report published on Thursday, the forecasters point out that the water temperatures in tropical regions are currently warmer than usual for this time of the year. They also highlight the generally weak wind shear that was present across much of the Caribbean and tropical Atlantic.
These are two important factors in the formation of tropical storms and hurricanes, as tropical systems require warm water to form and systems can become stronger as they move through parts of the world with low wind shear.
Perhaps the most important point to consider for the rest of the hurricane season is the status of ENSO, which is short for El NiÃ±o-Southern Oscillation. The ENSO range depends on the water temperatures in the Pacific Ocean near the equator off the west coast of South America.
When these water temperatures are warmer than normal, the Pacific is in the state of El NiÃ±o. When these temperatures are cooler than normal, the Pacific is in the state of La NiÃ±a. If the temperatures are neither significantly warmer nor cooler than normal, the phase is considered neutral.
It has been shown that the ENSO phase affects the frequency of tropical systems that can form in both the Pacific and the Atlantic. Periods of El NiÃ±o conditions are common with frequent tropical systems in the Pacific Ocean and fewer storms in the Atlantic due to an increase in wind shear (see figure below).
Ergo, when El NiÃ±o happens, we see less hurricanes in our vicinity. On the other hand, periods of neutral or La NiÃ±a conditions often keep the Pacific calm and allow air to rise above the Atlantic.
This, along with a decrease in wind shear, means that the strongest hurricane seasons we see in Florida are usually in a neutral ENSO time or in a La NiÃ±a time.
The following image, created by the National Oceanic and Atmospheric Administration, shows the general extent of the impact ENSO has on the tropical Pacific and Atlantic.
In the CSU report, forecasters note the current neutral period the Pacific is in and also confirm the possibility that La NiÃ±a conditions will develop again later this year when the hurricane season naturally picks up.
Let’s take a look at how this particular seasonal outlook has been going month by month so far this year. Looking ahead, an â€œaverageâ€ hurricane season will include the development of 14 named storms, seven of which will achieve hurricane status and of these 3 will become major hurricanes.
The term severe hurricane refers to any system that scores at least Category 3 on the Saffir-Simpson wind intensity scale. It is important to mention here that the term is used lens, Not subjective.
A hurricane that never hits land or disturbs anyone at all is a major hurricane as long as it becomes at least Category 3. A storm that hits land and does a lot of damage can subjectively be a major hurricane to the people it hits, but for objective records it would only be recorded as such if at some point in its lifespan it would have Category 3 status achieved.
In July, the CSU’s outlook was for 20 named storms, with nine hurricanes and four major hurricanes. With the release of this week’s report, those numbers have been modestly scaled back with 18 storms and eight hurricanes expected.
The number of major hurricanes forecast has not changed.
You can read the full seasonal forecast report from the CSU at the beginning of August here.
Are you prepared for hurricane season? Our free NBC2 First Alert Hurricane Guide can get you started. Check it out here.