2018 09 17 Hurricane

Atlantic Hurricane Season Forecast 2023

August is in its last week, and four named storms have formed just in the past week.  Of the four, we are predicting Franklin to develop into the second hurricane of the season over the next 3-5 days.  That makes a total of nine name storms so far this season, with two of them (including Franklin) becoming hurricanes. Nine named storms by late August is certainly an above normal number.

The Atlantic Hurricane Season Risk Map above shows risk areas for impact and the predicted number of storms.

El Niño is Here to Stay

There is no question that El Niño has developed in the Tropical Pacific.  Cooler water that had been flowing southward along the coast of California has stopped.  An El Niño typically results in more hurricane activity in the East and Central Pacific and less activity in the Atlantic side.  This is due to a combination of sinking air in the Caribbean Sea and increased wind shear across the Tropical Atlantic. Of the two named storms that formed east of the Caribbean this August, both were highly-sheared, which is evidence that El Niño is having the expected impact on the deep tropics.  Though the water is very warm, the increased wind shear from El Niño is keeping them from becoming strong.

Atlantic Water Temperatures – Record Warmth

Water temperatures across the Atlantic Basin remain very much above normal.  However, warm water alone cannot cause hurricanes to develop if the atmosphere is not favorable.  Since the middle of July, the Atlantic has been dominated by a very dry Saharan Air Layer (SAL) and above-normal wind shear.  Tropical waves have been moving off the west coast of Africa in August, but they are running into strong westerly wind shear. This is why none has developed into a hurricane.  While the shear isn’t strong enough to keep the waves from becoming tropical storms, it is strong enough to keep the storms on the weaker side. 

Late August Forecast - Reducing the Predicted Numbers

The season storm total remains at 9 named storms, including likely 2 hurricanes for the rest of August.  The number of named storms is definitely above normal, but only two hurricanes may be a little below normal through August.  Long-range forecasts from the European model are for activity the rest of the season to be close to normal.  While we think that the total number of named storms through the season will be above normal. The total number of hurricanes and major hurricanes may be close to normal (7 hurricanes / 3 major hurricanes).  We think that the season will end with a total of 17 named storms, including 7 hurricanes and 3 major hurricanes.  Those totals would be just a little above normal. 

Concerning the areas most likely to be impacted, we still think that the northeast Caribbean through the Bahamas to south Florida is in a slightly higher risk zone, as are the Carolinas.  Given the strength of the ridge that has dominated Texas and Louisiana all summer, producing the record warm and dry conditions, we debated whether the area from the middle Texas coast through Louisiana might be at a little lower of a hurricane risk than normal, but decided to indicate a normal risk there.  There are signs that the ridge may be weakening by the end of August.  In addition, we have raised the risk level across northern Mexico to near normal, mostly due to the stronger ridge that has dominated the northwest Gulf this summer.  If the ridge does not weaken, then storms entering the Gulf could track westward into Mexico.

Download Atlantic Hurricane Season Outlook PDF >

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