Tropics To Make An Active Return in 2007?

by Jim Hudgins

 

 

After a much slower than expected 2006 Atlantic tropical storm season, ingredients appear to be aligning for a return to above normal activity again for the 2007 season. The 2006 season, which appeared ready to follow closely to the record setting 2005 season, never really got on track after an early season June system (Alberto), and ended much sooner than expected with the passage of Isaac off Newfoundland in early October. The total number of classified cyclones for 2006 was 10, with 9 named systems (Fig 1), and 1 unnamed brief tropical storm that was re-classified after the season ended. Of these 10 systems, 5 were hurricanes including a couple major storms (Category 3 or higher), with the remaining 5 being tropical storms. Although most of these never affected the U.S. mainland, the number of storms actually ended up close to climatological normal levels of 10 named storms, with 6 being hurricanes and 2 intense hurricanes.

 

 

Fig.1. Storm tracks from 2006 across the Atlantic basin.

Fig.1. Storm tracks from 2006 across the Atlantic basin.

 

Only the remnants of a couple of these systems affected the local area and both were short lived while causing only isolated flooding problems. The low pressure system that once was Tropical Storm Alberto brought a couple inches of rain to parts of the Piedmont in mid June followed by Tropical Depression Ernesto which crossed the Tidewater on September 1st. This system which was briefly a weak hurricane in the Gulf of Mexico dumped up to 4 inches of rain in spots along and east of the Blue Ridge in Virginia, and indirectly caused two day rainfall totals of over 5 inches in the mountains of Northwest North Carolina.

 

The updated 2007 forecast (via Colorado State University) made in early April calls for a much more active tropical weather season with a prognosis of 17 named storms including 9 hurricanes. The climatological normal (based on the period between 1950 and 2000) is around 10 named storms of which 6 become hurricanes. Of the 9 hurricanes forecast for this season, 5 are expected to develop into intense storms (Category 3-4-5) (Fig. 2). This is also above the 50 year normal of 2 major hurricanes in an Atlantic season. This projected increase in the number of tropical storms is largely due to the dissipation of El Nino conditions in the Pacific, as well as above normal sea surface temperatures across the North Atlantic. In addition, the forecast probability for at least one major hurricane to make landfall on the entire U.S. coastline is 74 percent, with the average being around 52 percent.

 

 

 

 

Category

Wind speed

Storm surge

Effects

 

mph
(km/h)

ft
(m)

Damage

(Structures)

5

≥156
(≥250)

>18 (>5.5)

Catastrophic

4

131–155
(210–249)

13–18
(4.0–5.5)

Extensive

3

111–130
(178–209)

9–12
(2.7–3.7)

Significant

2

96–110
(154–177)

6–8
(1.8–2.4)

Some

1

74–95
(119–153)

4–5
(1.2–1.5)

Minimal

Tropical
storm

39–73
(63–117)

0–3
(0–0.9)

Little

Tropical
depression

0–38
(0–62)

0
(0)

None

Figure 2. Storm categories including winds, surge, and damage.

 

 

Storm names for the upcoming 2007 season are as follows:

Andrea

Humberto

Olga

Barry

Ingrid

Pablo

Chantal

Jerry

Rebekah

Dean

Karen

Sebastien

Erin

Lorenzo

Tanya

Felix

Melissa

Van

Gabrielle

Noel

Wendy