By:
Bob Henson
, 8:34PM,GMT on November 5,2015
Figure 1. VIIRS image of Megh in its formative stages over the Arabian Sea on November 4, 2015. Image credit: NOAA.
Figure 2. Enhanced infrared image of Cyclone Megh, with icons showing forecast track for the next two days. Image credit: NOAA/NESDIS.
Megh is moving just south of due west around the base of an broad upper-level high that should put the cyclone on a steady west-southwest track for the next several days. Vertical wind shear is low (10 knots or less), and sea-surface temperatures are at record levels across the North Arabian Sea, although Megh could encounter some cooler patches of water upwelled by the passage of Chapala. The 15Z forecast from JTWC brings Megh close to hurricane strength as it passes just south of Socotra, the remote Yemeni island slammed by Chapala’s south side. JTWC’s forecast track then nicks the north end of Somalia and brings Megh into the Yemen coast as a minimal tropical storm, while the IMD forecast track keeps Megh a bit further north. The 12Z HWRF model paints a true deja-vu scenario, with Megh passing just north of Socotra as a Category 3 storm, then making landfall on the central Yemen coast as a strong tropical storm. Given the unusually favorable conditions, I would not be surprised to see Megh reach at least Category 1 or 2 strength, assuming it does not pass directly over Chapala's track.
Cyclone Chapala left at least 8 fatalities and more than 200 injuries and destroyed dozens of structures in Yemen, including Socotra. About 3000 families were displaced, according to a recent AFP report. Humanitarian aid, including food and medical supplies, has been flowing from Oman, the United Arab Emirates, and the World Health Organization to Yemen, where the ongoing civil war has complicated relief efforts.
Aside from Chapala, only two other tropical cyclones are known to have made landfall in Yemen in the last 125 years: a destructive tropical depression in 2008, which caused an estimated 200 deaths, and a tropical storm-strength cyclone in 1960. The impact of the 2008 cyclone was magnified by heavy rains that had fallen just days earlier from the remnants of another tropical cyclone. Likewise, if Megh did make landfall on a track like Chapala’s, the potential for flooding this time could be even worse. NASA satellite analyses indicate that Chapala’s rains were considerably less than models had predicted on the Yemen mainland, but still on the order of 8-16”, with perhaps as much as 24” on Socatra.
Figure 3. Evacuees walk with their belongings in the area around Sinujiif, Somalia, on November 14, 2013, after a ferocious storm and days of heavy floods associated with a tropical depression that led to more than 100 deaths in the country’s northeastern Puntland region. Image credit: Mohamed Abdiwahab/AFP/Getty Images.
Somalia has had more experience with tropical cyclones than Yemen in recent years. The deadliest was a tropical cyclone (making landfall at tropical storm strength, according to JTWC) that moved onto the east-central Somali coast on November 22, 2013. The cyclone triggered rains that took at least 162 lives, many of them children and elderly residents who died of exposure. This storm (TD ARB01) struck just days after Typhoon Haiyan, so it gained relatively little media attention. As Jeff Masters noted at the time, several other tropical cyclones have hit Somalia in modern records: Murjan (October 2012), Agni (December 2004), ARB01 (November 1994), ARB04 (December 1992), Tropical Cyclone 4B (December 1984), and TS 1 (May 1984).
All of the above were late-season storms except for 1984’s TS 1, which made landfall on the north coast of Somalia after becoming the only North Indian cyclone on record to cross the entire Gulf of Aden.
Figure 4. Tracks of all tropical cyclones that have made landfall in Somalia since the Joint Typhoon Warning Center began keeping records of storm intensity for this region in 1972. See text at left for more on each storm. Image credit: Phil Klotzbach, Colorado State University.
Caribbean disturbance to send moisture into Gulf of Mexico
For the next five-day period, the National Hurricane Center puts 20% odds on development of a tropical wave now generating extensive showers and thunderstorms over the northwest Caribbean and southern Gulf of Mexico. Moderate wind shear (10-20 knots) and interaction with the Yucatan Peninsula will limit any development for the next day or two. Another brief window will open as the system moves into the Bay of Campeche, where weaker wind shear prevails.
Extreme warmth for early November in Michigan, Florida
Much of the eastern two-thirds of the United States was bathed in unusual autumn mildness at midday Thursday, with temperatures in the 70s and 80s from Texas to Michigan and east to New Hampshire. All-time highs for November were notched on Wednesday at several far-flung locations, including Flint, MI (80°F) and Tampa, FL (92°F). The low since midnight at Traverse City, MI, was a summerlike 62°F; if that reading holds till midnight Thursday night, it’ll be the lakeside city’s warmest November minimum on record. Most of Florida has seen a solid week of record- or near-record heat. In Tallahassee, the first four days of November were a full 4°F warmer than any other four-day November stretch in the city's weather history. My vote for the most impressive spot is Key West, where the last time the temperature dipped below 80°F was nearly a week ago--on Friday, October 30. Each night since Halloween has set a record-warm minimum for the date of either 80°F or 81°F. The 81°F readings on Sunday and Monday are the warmest November daily minima ever observed in Key West, where recordkeeping began in 1872. We can expect more daily and monthly records to tumble over the next couple of days before the mild weather over most of the eastern U.S. is pushed offshore by a seasonably strong cold front, accompanied in many areas by strong thunderstorms. A tornado watch was in effect Thursday afternoon over eastern Oklahoma and north Texas, and flash flooding is again a threat late Thursday into Friday from northeast into southern TX.
The associated upper-level storm has brought welcome snowfall across much of the mountainous West, including the recently snow-starved Sierra Nevada. Even Flagstaff, AZ, got in on the act, with almost a foot of snow piling up there. Strong westerly flow at upper levels will bring another powerful storm into the West early next week, with more heavy rains possible later next week in the beleaguered south-central states.
Figure 5. General view of a flooded area in the city of Villahermosa in Mexico’s Tabasco state on November 1, 2007. More than 1 million people were affected by the flooding across Tabasco and Chiapas. Image credit: Gilberto Villasana/AFP/Getty Images.
Looking back at the great November 2007 flood in southern Mexico
Norman Avila, a software engineer based in Guatemala City and a longtime Weather Underground member, is wrapping up a three-week stint at WU headquarters in San Francisco as part of a fellowship sponsored by the International Center for Journalists. The ICFJ brings journalists, technologists and digital entrepreneurs from Latin America to the United States to train and embed in U.S. digital organizations. While on site, Norman has been meeting with various WU staff, gaining insights that he hopes to apply to his own Spanish-language website, ClimaYa.com, which is focused on natural disasters in Central America. Norman has also found time to produce his first blog post for WU, which analyzes the catastrophic flood that struck Mexico's Tabasco state in the fall of 2007. As much as 80% of Tabasco was estimated to be under water at the height of the flood, which affected more than a million people. Thanks for contributing to WU, Norman!
Bob Henson
No comments:
Post a Comment