WunderBlog Archive » Category 6™

Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.

TD 2-E a heavy rain threat to Mexico; 150th anniversary of only U.S. May hurricane

By: Dr. Jeff Masters, 4:06 PM GMT on May 28, 2013

Tropical depression Two-E has formed in the Eastern Pacific, centered about 200 miles west-southwest of the Mexico/Guatemala border. The storm will bring very heavy rains capable of causing dangerous flash floods and mudslides to Mexico's Bay of Tehuantepec area over the next 2 - 3 days. Radar out of Puerto Angel, Mexico shows that heavy rains have already pushed ashore along portions of the Mexican coast, and satellite loops show an impressive but moderately disorganized area of heavy thunderstorms associated with TD Two-E, with some spiral bands on the storm's south side. With wind shear a low 5 -10 knots and ocean temperatures a very warm 30°C, conditions are ripe for further development, and I expect TD Two-E will be a tropical storm when it makes landfall on Wednesday along the Mexican coast in the Bay of Tehuantepec. The storm is close enough to the coast that it is unlikely a hurricane can form before landfall.

Figure 1. Latest satellite image of TD Two-E.

Development unlikely in the Atlantic this week
If TD Two-E continues to push northwards late this week and cross into the Gulf of Mexico, conditions do not favor development of the disturbance into an Atlantic tropical depression, as 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. The Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, is currently located in the Eastern Pacific, but is weak and difficult to discern. According to NOAA's May 27 MJO discussion, there is an increased probability of tropical cyclone formation over both the Eastern Pacific and Caribbean this week, and over the Caribbean next week. The GFS model has been trying to spin up a tropical depression in the Western Caribbean or Gulf of Mexico next week in a number of its runs over the past few days, but these runs have been very inconsistent on the timing and location of such a development. Tropical cyclone genesis forecasts more than four days out are highly unreliable, and we should just view the GFS model's predictions of a tropical depression next week as a sign that we have an above-average chance of an Atlantic tropical cyclone forming then. The European (ECMWF) model has been much less enthusiastic about a tropical depression forming in the Atlantic next week.

Figure 2. Track of the May 28, 1863 hurricane--the only hurricane on record to hit the U.S. in May. Image credit: Mike Chenoweth and the Bulletin of the American Meteorological Society.

150th anniversary of the only U.S. hurricane to make landfall in May
May 28 is the 150th anniversary of the only U.S. hurricane to make landfall in May--the May 28, 1863 hurricane that struck northwest Florida, killing at least 72 people. The hurricane hit nearly two weeks earlier than the next earliest U.S. landfalling hurricane, Hurricane Alma of June 9, 1966. (Tropical Storm Beryl of May 28, 2012 came close to being a May hurricane, bringing 70 mph winds to the coast near Jacksonville Beach, Florida.) According to a new paper by hurricane historians Mike Chenoweth and C. J. Mock, accepted for publication in the Bulletin of the American Meteorological Society, "Among the most unusual and unexpected hurricanes in United States history is the only hurricane to make landfall in the month of May. This recently re-discovered storm that struck northwest Florida on 28 May 1863 created a natural disaster in the area that became lost to history because it was embedded in a much larger and important manmade event, in this case the U.S. Civil War. We document the arrival of this storm both historically and meteorologically and anachronistically name it Hurricane “Amanda” in honor of the Union ship driven ashore by the hurricane. The hurricane revealed deficiencies and strengths in combat readiness by both sides. Meteorologically, the storm nearly achieved major hurricane status at landfall and its absence from modern data bases of tropical cyclone activity is a useful reminder to users of important gaps in our knowledge of tropical cyclones even in the best-sampled storm basins."

Figure 3. Severe weather outlook for Tuesday, May 28, calls for a "Slight Risk" of severe weather over portions of the Midwest. 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 Monday, with NOAA's Storm Prediction Center (SPC) logging fourteen preliminary tornado reports, mostly in Nebraska and Kansas. No damage or injuries were reported from these tornadoes, as they stayed over unpopulated rural areas. One tornado in North Central Nebraska was intercepted by the Tornado Intercept Vehicle 2 (TIV2), which reported EF-3 to EF-4 winds before the tornado ripped off their weather instruments (Video 1.) The latest forecasts from NOAA's Storm Prediction Center call for an active severe weather period all week in the Midwest, with a "Slight Risk" of severe weather Tuesday and Thursday, and a "Moderate Risk" on Wednesday.

Video 1. Stormchasers Brandon Ivey and Sean Casey drove the Tornado Intercept Vehicle 2 (TIV2) into a violent EF-3 or EF-4 wedge tornado northeast of Smith Center, Kansas on Monday, May 27, 2013. They estimated that wind speeds were 150 - 175 mph before the tornado ripped the instruments off the top of the TIV2. This video captures the intensity of the storm as it moves over the TIV2. Since the storm occurred near sunset and the thick clouds blocked out much of the sun, it's tough to see much except thick debris. To license this footage, contact ‪http://www.StormChasingVideo.com‬.

Wunderblogger Lee Grenci has a new post this morning, The Moore Tornado, describing how the rapid intensification of the May 20, 2013 Moore, Oklahoma tornado occurred.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.