Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 4:38 PM GMT on September 03, 2007
Hurricane Felix put on an incredibly ferocious burst of intensification last night, winding up into a small but potentially catastrophic Category 5 hurricane. Felix is the second-fastest storm in the Atlantic to intensify to Category 5 strength from a tropical depression. Felix required just 51 hours to reach Category 5 strength after it started as a tropical depression. That is a truly remarkable intensification rate, considering most tropical cyclones take 3-5 days to organize into a Category 1 hurricane. The only hurricane that intensified faster was Hurricane Ethel of 1960.
Figure 1. Satellite image of Felix as it entered its rapid intensification cycle to become a Category 5 hurricane. A NOAA P-3 Hurricane Hunter aircraft was forced to abort its mission because of extreme turbulence shortly after this photo was taken.
Hurricane Hunters walloped by Felix
NOAA Hurricane Hunter aircraft N42RF experienced a truly awesome and terrifying mission into the heart of Hurricane Felix last night. Flying at 10,000 feet through Felix at 7pm EDT, N42RF dropped a sonde into the southeast eyewall. The swirling winds of the storm were so powerful that the sonde spun a full 3/4 circle around the eye before splashing into the northwest eyewall. It is VERY rare for a sonde to make nearly a complete circle around the eye like this. As the plane entered the eye of the now Category 5 hurricane, they found a 17-mile wide stadium lit up by intense lightning on all sides. The pressure at the bottom of the eye had hit 934 mb, and the temperature outside, a balmy 77 degrees at 10,000 feet. This is about 24 degrees warmer than the atmosphere normally is at that altitude, and a phenomenally warm eye for a hurricane. N42RF then punched into the northwest eyewall. Flight level winds hit 175 mph, and small hail lashed the airplane as lighting continued to flash. Then, the crew hit what Hurricane Hunters fear most--a powerful updraft followed a few seconds later by an equally powerful downdraft. The resulting extreme turbulence and wind shear likely made the aircraft impossible to control. Four G's of acceleration battered the airplane, pushing the aircraft close to its design limit of 6 G's. Although no one was injured and no obvious damage to the airplane occurred, the aircraft commander wisely aborted the mission and N42RF returned safely to St. Croix. N42RF is the same aircraft that survived a pounding of 5.6 g's in the eyewall of Hurricane Hugo in 1989. A special inspection of the aircraft is planned for today to determine if it is fit to fly further missions into Felix, and its scheduled afternoon flight into the hurricane was canceled. Hurricane Hunter missions since have fared better, and no more extreme turbulence has been reported.
Some good news for Central America
Although Hurricane Felix has intensified into a truly awesome and potentially catastrophic hurricane, the prospects of a major flooding catastrophe in Honduras and Nicaragua are much lower today than they appeared yesterday. Firstly, the dramatic intensification cycle has spun Felix into a very small, tight coil. A storm of this small size is much less likely to pull in moisture from the Pacific Ocean over the mountains of Honduras like Hurricane Fifi of 1974 did. Secondly, the strong ridge of high pressure pushing Felix westward has intensified, resulting in a greater forward speed for the hurricane. Felix is now moving at 21 mph, and will not slow much during its passage over Honduras. This will keep rainfall amounts lower than I expected. Thirdly, it now appears likely that Felix will hit the Honduras/Nicaragua border area, a very sparsely populated region known as "The Mosquito Coast". The region is mostly a large expanse of marshy wetlands. This track will result in the rapid weakening of Felix, limiting the rainfall from the storm. A passage just north of Honduras would have been far more disastrous. It will still be bad for Honduras--NHC is predicting 5-8 inches of rain, with isolated amounts up to 12 inches--but this is far short of the 20+ inches of rain that fell during catastrophic Hurricane Fifi and again in 1998 during Category 5 Hurricane Mitch. The nations of Nicaragua, El Salvador, Guatemala, Belize, and Mexico can also breather easier, as Felix's rains should not cause the kind of extreme flooding a larger storm would have caused. It now appears the Felix will stay too far south to be influenced by the trough of low pressure forecast to move across the U.S. later this week, so Texas appears safe from the storm.
Links to follow for Felix
Puerto Cabezas, Nicaragua current conditions
Puerto Lempira, Honduras current conditions
Trujillo, Honduras current conditions
La Cieba, Honduras current conditions
Roatan, Honduras current conditions (an island of the central coast badly hit by Hurricane Mitch).
Google Map of the region, with current conditions plotted (zoom out to see more than just the one station at the Honduras/Nicaragua border).
Not much has changed with the tropical wave (98L) in the mid-Atlantic, halfway between Africa and the Lesser Antilles since yesterday, so I will mostly repeat yesterday's discussion. The system has a closed circulation and a small area of heavy thunderstorm activity on the west side of the center. Wind shear of 15 knots from strong upper-level winds from the east-southeast are preventing thunderstorm activity from building on the east side of the storm. Several of the reliable models are forecasting that this shear will fall below 15 knots by Tuesday. There is some dry air to the northeast for the disturbance to contend with, but I expect 98L will be able to overcome this dry air and shear and organize into a tropical depression. Thursday is the earliest this would happen. The UKMET is the only model that develops 98L into a tropical depression.
98L is nearly stationary, and it will be at least six days before it will threaten the Lesser Antilles Islands. A strong trough of low pressure will pass north of 98L Tuesday and Wednesday, which could impart a more northwesterly motion to the storm.
Elsewhere in the tropical Atlantic
Several computer models develop a tropical depression off the South Carolina coast by Wednesday or Thursday, along an old frontal boundary. An area of disturbed weather has already formed here, and will bear watching over the next few days. You can track this using long range radar out of Jacksonville, Florida. The eventual track such a storm might take is highly uncertain--the NOGAPS foresees a threat to North Carolina, the UKMET and ECMWF has the system looping back and hitting Florida, while the GFS has the storm heading out to sea near Bermuda.
Henriette takes aim at Baja
Tropical Storm Henriette continues to churn along the Pacific coast of Mexico towards Baja, and could bring hurricane conditions to Baja on Tuesday. Despite a favorable environment, Henriette has not been able to intensify into a hurricane. Visible satellite loops show increased thunderstorm activity wrapping around the center, so the Hurricane Hunters may find a hurricane when they arrive at the storm this afternoon. The remains of Henriette could bring heavy rains to Arizona on Friday.
Links to watch for Henriette
Los Cabos radar
San Jose Del Cabo observations
My next update will be Tuesday morning.
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