Update 11:00 PM EDT: Igor still intensifying, now at 130 knots (Cat 4) and now forecast to become a Category 5 within the next 12-hours. See NHC bulletin at the end of this post.
Hurricane Igor has rapidly intensified into a Category 4 storm over the open Central Atlantic. Winds are expected to remain above 115 knots for the next several days which will allow for considerable Accumulated Cyclone Energy production. The North Atlantic basin as a whole will almost assuredly be above the climatological average in terms of ACE for 2010. I keep track of the global tallies on my Florida State University page. Note that the Pacific basin has been historically inactive due to the onset of the strong La Nina. The Northern Hemisphere ACE as a whole is on pace to be the lowest since 1977, and be even lower that the wimpy total of 2007.
The NCEP GFS and ECMWF forecast models both indicate that Igor will be a fish storm (of course fingers crossed for Bermuda escaping the storm):
Figure. ECMWF maximum wind speed for the next 10-days. Note that this model is capable of generating more reasonable wind speeds for tropical cyclones (actual Category 4 and 5 winds) due to the incredible grid point resolution of the forecast model (T1279 = ~16 km globally).
Homework assignment: The name Ivan was used 3-times prior to being retired in 2004. Here is the list maintained at the NHC of named retired and the year the storm occurred. The rules for retirement are defined by the WMO, but a landfall does not necessarily mean that a given storm name will not be used again 6-years later.
Trivia questions to determine: instead, over the past 60-years, regardless of name, say that we retire all names of “hurricanes 64 kts+” that make landfall anywhere, which letter would be the most retired? What’s the next letter that is due to be retired?
HURRICANE IGOR ADVISORY NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 PM AST SUN SEP 12 2010
…IGOR STILL INTENSIFYING…
SUMMARY OF 1100 PM AST…0300 UTC…INFORMATION
ABOUT 1005 MI…1620 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS…150 MPH…240 KM/HR
PRESENT MOVEMENT…W OR 270 DEGREES AT 13 MPH…20 KM/HR
MINIMUM CENTRAL PRESSURE…935 MB…27.61 INCHES
WATCHES AND WARNINGS
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.
DISCUSSION AND 48-HOUR OUTLOOK
AT 1100 PM AST…0300 UTC…THE EYE OF HURRICANE IGOR WAS LOCATED
NEAR LATITUDE 17.6 NORTH…LONGITUDE 47.8 WEST. IGOR IS MOVING
TOWARD THE WEST NEAR 13 MPH…20 KM/HR. A TURN TOWARD THE
WEST-NORTHWEST WITH SOME DECREASE IN FORWARD SPEED IS EXPECTED TO BEGIN LATE MONDAY AND TUESDAY.
MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 150 MPH…240
KM/HR…WITH HIGHER GUSTS. IGOR IS A CATEGORY FOUR HURRICANE ON
THE SAFFIR-SIMPSON HURRICANE WIND SCALE. SOME FLUCTUATION IN
INTENSITY IS LIKELY DURING THE NEXT 48 HOURS…AND IGOR COULD
BECOME A CATEGORY FIVE HURRICANE ON MONDAY.
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