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 , 2:02 PM GMT on May 29, 2013
Hurricane warnings are flying for the Pacific coast of Mexico, where Tropical Storm Barbara is rapidly intensifying as it makes landfall. Barbara should be ashore by 2 pm EDT (11 am PDT), and is expected to intensify to a Category 1 hurricane with 75 mph winds before landfall. Barbara formed on Tuesday night (May 28), an unusually early date for the formation of the Eastern Pacific's second storm of the year. The record earliest second storm of the year occurred just last year, on May 21 (Tropical Storm Bud.) The previous record was set in 1984, when the second named storm (Boris) formed on May 29. Reliable records of Eastern Pacific hurricanes go back to 1949. Barbara wasted no time getting organized, and is gathering strength in impressive fashion as it nears landfall in Mexico's Bay of Tehuantepec area. The storm's main threat is very heavy rains of up to a foot, which will be capable of causing dangerous flash floods and mudslides over the next 2 - 3 days. However, wind damage and the expected 3 - 5 foot storm surge are also a concern, since the area of the coast it is hitting, though not heavily populated, has very little hurricane experience. According to NOAA's Historical Hurricane Tracks website, only one Eastern Pacific hurricane has ever hit the Bay of Tehuantepec--Category 1 Hurricane Rick of 1997. Radar out of Puerto Angel, Mexico shows that Barbara has built a partial eyewall, and the storm has already spread heavy rains ashore along portions of the Mexican coast. Satellite loops show that Barbara is a relatively small storm, with a modest area of heavy thunderstorms.
Figure 1. Radar image of Barbara from Puerto Angel, Mexico, taken at 9:30 am EDT (6:30 am PDT) May 29, 2013. Image credit: CONAGUA.
May tropical storm landfalls are rare in the Eastern Pacific
Only eight named storms that formed in May have hit land in the Eastern Pacific since accurate hurricane records began in 1949--an average of one storm every eight years, according to NOAA's Historical Hurricane Tracks website. Just one of these May storms made landfall as a hurricane--Category 1 Hurricane Agatha of 1971, which hit Mexico west of Acapulco. But one of the deadliest and most destructive Eastern Pacific tropical cyclones of all-time was a May storm that never reached hurricane strength--Tropical Storm Agatha of May 29, 2010, which had top winds of only 45 mph at landfall. Agatha dissipated just one day after making landfall, but its remnants lingered over Central America for six days, dumping torrential rains that triggered deadly flash floods and landslides; Mazatenango, Guatemala, reported 22.27 inches of rain from May 25 - 30, 2010. At least 190 people died, mostly in Guatemala, making Agatha the 7th deadliest Eastern Pacific tropical cyclone in history. Agatha's $1.2 billion in damage made it the 6th most expensive Eastern Pacific tropical cyclone on record. Fortunately, Barbara is hitting a region of the coast that is relatively sparsely populated compared to where Agatha hit, and Barbara is not likely to cause anywhere close to the devastation that Agatha wrought.
Figure 2. Journey to the center of the Earth: a massive sinkhole 66 feet (20 m) across and 100 ft (30 m) deep opened up on May 29, 2010 in Guatemala City after heavy rains from Tropical Storm Agatha. The sinkhole collapsed suddenly, taking a three-story house that was used as factory, claiming fifteen lives. The sinkhole formed because Guatemala City is built upon volcanic pumice deposits, which are unconsolidated and of low density, allowing easy erosion. According to Sam Bonis, a geologist at Dartmouth College, because of lax city zoning regulations and building codes, leaking pipes went unfixed long enough to create the conditions necessary for this hole to form (it technically wasn't a sinkhole, since sinkholes form in limestone rock.) How do you patch something like this?
Tropical cyclone development unlikely in the Atlantic during the coming seven days
Barbara is expected to push northwards and cross into the Gulf of Mexico by Friday, but the storm is small enough and moving slowly enough that Barbara will likely dissipate before reaching the Gulf. If the storm were able to maintain at least tropical depression status and cross into the Gulf, it would keep the name Barbara. If Barbara were to dissipate before reaching the Gulf, then regenerate into a tropical storm in the Gulf, it would be named Andrea. However, conditions do not favor redevelopment of Barbara's remnants into an Atlantic tropical depression, since wind shear is expected to be quite high over the Gulf late this week. None of the reliable computer models is calling for tropical cyclone development in the Atlantic during the next seven days.
AP will be doing a hurricane twitter chat on Thursday at 1 p.m. EDT: #APStormChat
The National Hurricane Center is doing a hurricane chat on Thursday at 2 pm EDT: #HurriChat
Figure 3. Large tornado on the ground near Corning, Kansas, at 4:32 CDT May 28, 2013. Image credit: Ron Heinen, via twitter.
Figure 4. Radar reflectivity image of the tornado that hit Corning, Kansas at 4:32 pm CDT May 28, 2013.
Figure 5. Severe weather outlook for Wednesday, May 29, calls for a "Moderate Risk" of severe weather over much of Oklahoma and Kansas, plus portions of the Texas Panhandle. You can follow today's severe weather outbreak from our Severe Weather page.
Multi-day severe weather outbreak in the Midwest continues today
It was an active day for tornadoes in the Midwest on Tuesday, with NOAA's Storm Prediction Center (SPC) logging eighteen preliminary tornado reports, with twisters touching down in Nebraska, Kansas, Texas, Michigan, and Pennsylvania. No injuries were reported from these tornadoes, but damage was reported near Corning, Kansas, and Fenton, Michigan. The latest forecasts from NOAA's Storm Prediction Center call for a "Moderate Risk" of severe weather today (Wednesday), with the possibility of a significant tornado outbreak over much of Oklahoma and Kansas, plus portions of the Texas Panhandle.
Wunderblogger Lee Grenci has a post, The Moore Tornado, describing how the rapid intensification of the May 20, 2013 Moore, Oklahoma tornado occurred.
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