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 , 1:42 PM GMT on October 11, 2011
Rain bands from powerful Category 3 Hurricane Jova are already deluging the southwest coast of Mexico as the storm heads towards landfall late this afternoon between Manzanillo and Puerto Vallarta. Recent satellite loops show the hurricane has weakened since yesterday afternoon, with the eye no longer visible and the cloud pattern no longer as symmetric. Moderate wind shear of 15 - 20 knots due to strong upper-level winds out of the southeast managed to inject some dry air into the core of Jova that disrupted the storm's eyewall, and it is unlikely the hurricane will be able to intensify beyond its current 115 mph strength before landfall. It is more likely that Jova will weaken as it approaches land, due to the storm's small size, which makes is vulnerable to disruption when the outer portion of the circulation hits the mountains along the Mexican coast. If Jova maintains its Category 3 strength until landfall, it will rank as one of the ten most intense Pacific hurricanes to hit Mexico since record keeping began in 1949, according to a comprehensive list of Eastern Pacific hurricane landfalls at Wikipedia. However, I expect Jova's interaction with the high mountains of Mexico will knock it down to a Category 2 storm with 100 - 105 mph winds by landfall. Hurricane-force winds extend outwards only 15 miles from the center of Jova, so a relatively small stretch of moderately to lightly-populated stretch of coast will see Jova's high winds and dangerous storm surge. A much larger swath of Mexico will see very heavy rains of 6 - 12 inches, and these rains are the primary threat from the hurricane.
The shape of the coast near Puerto Vallarta makes it difficult for a high storm surge to affect that city. Jova is passing far enough to the east of Puerto Vallarta that the winds in the Bay should be capable of elevating a surge to a height of just 1 - 2 feet above normal water levels, with perhaps a slight chance of a surge as high as 3 feet affecting the city. However, there will be high battering waves on top of the storm surge, and these waves may cause damage to ocean front property. I was in Puerto Vallarta during Hurricane Paine of 1986, and while we didn't see much of a storm surge, the coast experienced 10-foot waves that tore apart the sea wall protecting the swimming pool of the hotel I was staying at. The highest storm tide from Jova should occur near 9:55am CDT Wednesday morning, which is the time of high tide. Jova will be at its closest to Puerto Vallarta then, and is likely to be a strong tropical storm with 60 mph winds.
Figure 1. True-color MODIS image of Jova taken at 1:40 pm EDT October 10, 2011. At the time, Jova was a Category 3 hurricane with 125 mph winds. Image credit: NASA.
Figure 2. Rainfall forecast for Hurricane Jova from this morning's 2 am EDT run of the GFDL model. Image credit: Morris Bender, NOAA/GFDL.
Links to follow Jova
Wunderblogger Mike Theiss is in Barra de Navidad, just north-west of Manzanillo, and will be giving us live blogs and photos from the landfall of Jova, as his power and Internet connections permit.
>Puerto Vallarta webcam
Tropical Depression Irwin also headed for Mexico
Once Jova has made landfall, Tropical Depression Irwin, farther to the west, may also be a concern. The computer forecast models show that late this week, Irwin will approach the same stretch of Mexican coast Jova is affecting. However, Irwin is a weak storm that is may not survive, due to high wind shear, and may end up not bringing significant rains to Mexico.
Quiet in the Atlantic
There are currently no threat areas in the Atlantic, now that Invest 93L has moved ashore over the Southeast U.S. Invest 93L did have tropical storm force winds, and will be re-analyzed in the off-season by NHC to see if it did indeed have enough organization to qualify as an unnamed subtropical storm.
The ECMWF and NOGAPS models continue to predict that a strong tropical disturbance capable of becoming a tropical depression could form in the Western Caribbean early next week. Some of the spin and moisture for this storm could potentially come from an area of disturbed weather in the Eastern Pacific, (Invest 99E), that is currently just offshore of the Mexico/Guatemala border. Invest 99E is expected to move inland over Central America over the next few days, bringing very heavy rains capable of causing flash flooding and mudslides to Southeast Mexico, Guatemala, and El Salvador.
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