02 September 2014

Dolly forms in Bay of Campeche, landfall tonight

Over the past week, an easterly wave has been making its way across the Caribbean.  As it neared the Yucatan peninsula on Sunday, it began to get better organized.  Shortly after it crossed the peninsula and entered the Bay of Campeche, it was upgraded to Tropical Depression 5.  Then, at 5am EDT on Tuesday, it was upgraded to Tropical Storm Dolly.

Today, as of 8am EDT, Dolly is centered 145 miles east-southeast of La Pesca, Mexico and is moving west-northwest at 13mph.  At this rate, landfall will occur late Tuesday evening (local time).  Maximum sustained winds are 50mph and additional intensification is possible up until it makes landfall. The greatest threat from this storm will be the heavy rain and resulting mudslides and flash floods.

Dolly is the fourth named storm of the season, and ushers in the climatologically most active couple of weeks of the Atlantic hurricane season.  In the figure below, a timeline of the average tropical storm and hurricane counts are shown, and today's date is highlighted by a green line.  This season, the overall activity as measured by ACE (Accumulated Cyclone Energy) is just 54% of average as of today.

Dolly's origin and track is interesting because past storms in this "lineage" have been similar.  Prior to Dolly, Diana was the female name in this list (it was retired in 1990).  But, going back to 1990, Diana 1990, Dolly 1996, and Dolly 2008 all crossed the Yucatan peninsula and strengthened as they moved west... also note that all three of them were hurricanes at landfall.

Elsewhere across the basin, global models have been bullish on developing an easterly wave that's still over Africa, but is expected to enter the Atlantic on Thursday.  This wave had its origins over eastern Africa back on August 28th.  The next name on the list is Edouard.

Today is a very significant day in hurricane history.  On the evening of September 2, 1935, the infamous Labor Day Hurricane made landfall on Florida's Upper Keys (near Islamorada) as a Category 5 hurricane... and it remains the most intense U.S. landfall on record.  Maximum sustained winds were 185mph (stronger than Andrew and Camille); it generated a 18-foot storm surge that totally inundated the low-lying islands, and the incredible winds leveled everything in its path.  It was responsible for over 400 deaths.

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