Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 20:13 GMT le 01 septembre 2006
Hurricane John is hours away from a strike on the southern tip of Baja as a borderline Category 2 or 3 hurricane. The Air Force Hurricane Hunters found a central pressure of 958 mb, and top winds of 110 mph at the surface at about 10am PDT. John is expected to maintain this intensity up until landfall. John is a very small hurricane, and the exact point of landfall will make a critical difference on how much damage the storm does. A 50-mile wide section of the coast will experience hurricane force winds. Satellite animations of John's current track suggest it will move up the relatively sparsely populated east side of the Baja Peninsula, sparing the resort towns of Cabo San Lucas and San Jose del Cabo the worst of the eyewall's winds. Radar from Cabo is most impressive!
Figure 1. Visible satellite image of Hurricane John from 1:45pm EDT Friday 9/1/06. Tropical Storm Kristy is also visible. Image credit: NOAA Visualization Laboratory.
Given the small size of the hurricane, the impact on Baja is likely to severely disrupt the storm. A much weakened John should continue north along Baja, dumping copious amounts of rain along the way. John's rains may make it all the way to San Diego, but it would be a major surprise if the storm were a tropical depression by then.
NHC declares a new "invest" on African tropical wave
A tropical wave near 11N 39W, midway between Africa and the Lesser Antilles Islands, has developed a well-defined low level circulation today. There has been a moderate increase in the thunderstorm activity associated with this wave, and the NHC has just designated this wave as Invest 98L. The system is moving west at 10-15 mph, and is expected to be near the Lesser Antilles Islands Wednesday. Wind shear over the system is low, 5-10 knots, and the wave is over warm SSTs of 83-86F (28.5-30 C). Wind shear is forecast to remain low over the next few days, and the system has the potential to become a tropical depression by Sunday. The main inhibiting factor would seem to be the large area of dry air and African dust to the wave's north (have we heard that refrain before this season?) The SHIPS intensity model is very aggressive with this system, intensifying it to a hurricane by Tuesday. That's not going to happen, it takes a lot longer than that for disturbance to organize into a hurricane.
Figure 2. Preliminary model tracks for Invest 98L. These models are described at the NHC web site.
Dr. Gray's September 1 forecast
The hurricane forecast team at Colorado State University headed by Phil Klotzback and Dr. Bill Gray issued their September forecast for Atlantic hurricane activity today. They predict 5 named storms, 3 hurricanes, and 2 intense hurricanes for September, which is about normal for that month. They predict an additional 2 named storms and one hurricane in October, and one named storm in November. This would give the hurricane season of 2006 total of 13 named storms, 5 hurricanes, and 2 intense hurricanes. An average season has 11 named storms and 6 hurricanes. They credited dry air from the Sahara and more El Nino-like conditions than expected for the lower than average hurricane activity observed in August. Prices of oil, natural gas, and heating oil futures fell on commodity markets by 1-3% on the news of the forecast. The Klotzbach/Gray team originally forecast that 17 named storms would form this year.
Ernesto, now a tropical depression, has dumped up to a foot of rain on North Carolina and Virginia. I'll have a summary of some lessons learned from tracking the storm in tomorrow's blog.
Typhoon Ioke is no longer a super typhoon, having fallen below the 150 mph winds threshold for that designation. It is, however, still a Category 4 storm with 135 mph winds, and may stay a Cat 4 for three more days. However, its amazingly long run as an intense typhoon appear numbered--it's getting far enough north that a trough of low pressure should be able to grab it by Tuesday, weaken it, and pull it northwest towards Japan.
Some impressive satellite loops and 3-D images of Ioke passing Wake Island are available at the RTS Weather Station on Kwajelein Atoll.
Another wave to keep an eye on
The tropical wave near 16N 55W is surrounded by a large cloud of dry air and African dust, but has slowly been able to pump more moisture into its center each night over the past few days as thunderstorm development kicks up then dies away. The thunderstorm activity surrounding the wave has died away again this afternoon, but will probably pick up again tonight, during the normal nighttime peak in thunderstorm activity over the oceans. By Sunday, the wave may have enough moisture to develop. It should be in the Lesser Antilles Islands at that time.
I'll have an update Saturday morning.
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