These stats should be kept in mind when the invariably waiting-in-the-wing 'season cancel' posts start to pop up if we don't have the E storm in a week or a train of Cape Verde storms to monitor by the end of July.
"From 1966-2010, there have been 46 named storms that have formed in July. So, on average, you'll see a named storm form in July every year or so.
Of those, 20 were hurricanes, so expect a July hurricane every 2-3 years. Major hurricanes (Category three or stronger on the Saffir-Simpson Hurricane Wind Scale), are even more rare in July.
Since 1950, there have been only five major July hurricanes. That said, three of those major July hurricanes have occurred in the last six seasons.
Average percent of named storms in Atlantic Basin by month
Some recent seasons have bucked the "July quiet" conceptual model.
In July 2010, Hurricane Alex made landfall as the calendar turned to July in northern Mexico, wringing out torrential, flooding rain in the Rio Grande Valley and Monterrey, Mexico.
Two years earlier, Category-two Hurricane Dolly made landfall in South Texas in July 2008. There was also a rare July major hurricane, Bertha, in the central Atlantic that year.
The record-shattering 2005 hurricane season was very active in July.
Following landfall of Hurricane Cindy in southeast Louisiana, Hurricane Dennis was, at the time, the strongest July Atlantic Basin hurricane on record, before landfalling in the Florida Panhandle.
TWC Hurricane Expert, Dr. Rick Knabb (On Twitter | On Facebook) has vivid memories of that unusual July. "While I was at the National Hurricane Center, we looked at Category 4 Dennis in the Caribbean - and the overall pattern across the tropical Atlantic - and thought 'this is insane - it looks like September, not July!'"
Then, the only Category 5 July hurricane of record in the Atlantic Basin, Hurricane Emily, churned through the Caribbean, then tracked into the western Gulf of Mexico. In all, 5 named storms formed in July 2005.
That said...there were three straight Julys (1999-2001) during which not a single named storm formed.
Formation areas/storm tracks
Compared to June, named storms spread out into more real estate in July.
The Gulf of Mexico remains relatively active in July, though the western Caribbean Sea steps down a bit. Of course, storms that do form in the Gulf have "no way out", meaning they must make landfall somewhere along the U.S. or Mexican Gulf Coast.
TWC Hurricane Specialist, Bryan Norcross (Become a fan on Facebook) says two factors limit the number of July Atlantic tropical cyclones.
"Cold fronts, one of the 'seeds' of a tropical cyclone, are much less likely to reach the tropics in July vs. June. At the same time, water temperatures have not yet reached their peak."
Development can also occur from north of Puerto Rico to the Bahamas to Bermuda. The typical track would take most of these tropical cyclones away from the East Coast of the U.S., but remember, that's just an "average". At times, these storms can linger off the East Coast, churning up high surf leading to beach erosion and rip currents.
An area that "emerges", if you will, in July is near the Windward Islands, as tropical waves originating in Africa may begin to develop, in earnest.
"The tropical waves coming off of western Africa every 2-4 days are a little better defined than in June, says TWC Hurricane Expert, Dr. Rick Knabb. "That's one reason why we start to look farther east for development in July."
That said, the primary season for long-track tropical cyclones from the eastern Atlantic, known as "Cape Verde" storms, is in August and September."
July: Typical origins and tracks
link to article: http://www.weather.com/outlook/weather- ... 2011-06-30
