About Jeff Masters
Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 3:31 PM GMT en Noviembre 05, 2009
Hurricane Ida intensified at one of the fastest rates on record, and plowed ashore this morning in central Nicaragua as a Category 1 hurricane with 75 mph winds. It took just 24 hours from when the first advisory was issued for Tropical Depression Eleven until Ida reached hurricane strength. Since reliable satellite measurements began in 1970, Hurricane Humberto holds the record for fastest intensification from first advisory issued to hurricane strength--18 hours. (Actually, Humberto did the feat in 14 1/4 hours, but this was rounded off to 18 hours in the final data base, which stores points every six hours). There have been six storms that accomplished the feat in 24 hours--Hurricane Florence of 2000, Hurricane Erin of 1995, Hurricane Bonnie of 1992, Hurricane Earl of 1986, Hurricane Kate of 1985, and Hurricane Kendra of 1978. Ida now joins that short list of rapidly intensifying storms.
Ida will dump very heavy rains of 10 - 15 inches over northern Nicaragua and northeastern Honduras over the next two days, which will likely make it the deadliest storm of the 2009 hurricane season. However, Ida is a relatively small storm, and has not tapped the Pacific Ocean as a source of moisture. I think the NHC forecast of 15 - 20 inches of rain is overdone. The greatest rainfall disasters in Honduras history--caused by Hurricane Fifi of 1974 and Hurricane Mitch of 1998--were caused because these were large storms that were able to pull in moisture from both the Atlantic and Pacific. Ida will not approach these disasters in magnitude.
Figure 1. Microwave "weather radar in space" image of Ida at landfall this morning, at 6:17 am EST. Image credit Navy Research Lab, Monterey.
The forecast for Ida
Ida will likely spend a full two days over Nicaragua and Honduras, and there is a chance that Ida will dissipate. The HWRF and ECMWF don't show much surviving of Ida after crossing into the Western Caribbean. However, the other models like Ida's chances of surviving, and it is the case that the storm's core will be tracking over relatively low elevation land (Figure 2), increasing the chances that Ida can survive the crossing intact. If Ida survives the crossing and emerges into the Western Caribbean on Saturday, moderate wind shear of 15 - 20 knots and warm waters await it, and some modest strengthening is likely. A trough of low pressure in the Gulf of Mexico this weekend should be able to propel Ida northwards into the Gulf of Mexico. The long-term fate of Ida if it reaches the Gulf of Mexico is hard to guess at this point, though the odds are against Ida hitting the U.S. as a hurricane, due to high wind shear.
Figure 2. Projected track from the 10am EST NHC advisory from Thursday, 11/05/09, overlaid on a topographical map of Central America. Image credit: Wikipedia.
Looking at the past to predict the future
Perhaps the best way to estimate the chances of Ida surviving the crossing of Nicaragua and Honduras is to look at past storms that have followed similar tracks, to see if they dissipated or not. History favors Ida surviving the crossing. The two best analogue storms occurred in 1906 and 1908. Hurricane Eight of October 10, 1906, hit Nicaragua as a Category 3 hurricane, spent two days over land, weakening to a tropical storm, then emerged into the Western Caribbean and re-intensified into a Category 3 hurricane that hit Cuba and South Florida. On the other hand, Hurricane Nine of October 18, 1908, which hit Nicaragua as a Category 2 hurricane, dissipated after spending 1.5 days over land. Three other weaker systems have followed paths similar to Ida's, and all survived the crossing and re-intensified once over the Western Caribbean. Tropical Storm Gert of 1993 hit as a 40 mph tropical storm, spent two days over land, and survived to re-intensify to a tropical storm before hitting the Yucatan Peninsula. Hurricane Alma of June 1996 hit Nicaragua as a tropical depression, spent two days over land, and survived. Alma later intensified into a major Category 3 hurricane in the Gulf of Mexico. Tropical Storm Six of 1940 hit Nicaragua as a 45 mph tropical storm, spent 1.5 days over land, and survived the crossing. So, of the five storms to follow a path similar to Ida's projected path, four survived to re-intensify over the Western Caribbean.
I'll have an update Friday morning.
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.
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