Dr. Jeff Masters' WunderBlog

Posted by: Dr. Jeff Masters, 7:49 PM GMT on June 19, 2013

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Data from the Air Force Hurricane Hunters this afternoon indicates that Tropical Storm Barry has formed in the extreme southern Gulf of Mexico. The aircraft measured winds at their flight level of 1000 feet as high as 47 mph, which implies winds of at least 40 mph at the surface, using the usual 10% reduction rule for winds measured at 1000 feet. Barry has a small but growing area of heavy thunderstorms, as seen on satellite loops. The thunderstorms are steadily showing more organization this afternoon, and low-level spiral bands have begun to appear. Wind shear was a moderate 15 knots on Wednesday afternoon, but is expected to fall to the light range, 5 - 10 knots, during the 12 hours before landfall. Barry is taking a very similar track Tropical Storm Marco of 2008. That storm spun up quickly in the Bay of Campeche and developed sustained winds of 65 mph before making landfall in Veracruz State of Mexico. Small storms like Barry and Marco (which was the smallest tropical storm ever recorded in the Atlantic) can experience very rapid fluctuations in intensity. The Bay of Campeche is a region where the topography aids the spin-up of tropical cyclones, and I expect Barry will have time to attain sustained winds of 65 mph before making landfall late Thursday morning or early Thursday afternoon near Veracruz, Mexico. However, since the storm is so small, these winds would affect only a very small portion of the coast. Heavy rain will be the main threat from Barry, regardless of whether or not it makes landfall as a weak or strong tropical storm. A ridge of high pressure over the Gulf of Mexico should keep any of Barry's rains from reaching the U.S. Elsewhere in the tropical Atlantic, none of the reliable computer models is showing tropical cyclone development in the next seven days.

Figure 1. MODIS satellite image of Tropical Storm Barry at 12:40 pm EDT June 19, 2013. Image credit: NASA.

Barry's place in history
Barry is the second named storm of June 2013, and its formation date of June 19 is a full six weeks earlier than the usual August 1 date of formation of the season's second storm. Only two hurricane seasons since 1851 have had as many as three tropical storms form in June: 1936 and 1968. The formation of two Gulf of Mexico storms so early in the year does not necessarily suggest that we will have an active hurricane season. June storms forming in the Caribbean and Tropical Atlantic are typically a harbinger of an active hurricane season, though.

The formation of Tropical Storm Andrea and now Tropical Storm Barry in June continues a pattern of an unusually large number of early-season Atlantic named storms we've seen in recent years. Climatologically, June is the second quietest month of the Atlantic hurricane season, behind November. During the period 1870 - 2012, we averaged one named storm every two years in June, and 0.7 named storms per year during May and June. In the nineteen years since the current active hurricane period began in 1995, there have been sixteen June named storms (if we include 2013's Tropical Storm Andrea and Tropical Storm Barry.) June activity has nearly doubled since 1995, and May activity has more than doubled (there were seventeen May storms in the 75-year period 1870 - 1994, compared to six in the nineteen-year period 1995 - 2013.) Some of this difference can be attributed to observation gaps, due to the lack of satellite data before 1966. However, even during the satellite era, we have seen an increase in both early season (May - June) and late season (November - December) Atlantic tropical storms. Dr. Jim Kossin of the University of Wisconsin looked at the reasons for this in a 2008 paper titled, "Is the North Atlantic hurricane season getting longer?" He concluded that there is a "apparent tendency toward more common early- and late-season storms that correlates with warming Sea Surface Temperature but the uncertainty in these relationships is high." He found that hurricane season for both the period 1950-2007 and 1980-2007 got longer by 5 - 10 days per decade (see my blog post on the paper.)

Portlight receives $25K grant to help victims of Oklahoma tornadoes
The disaster relief charity founded by members of the wunderground community, Portlight.org, announced this week that they had received a $25,000 grant from Americares.org to replace wheelchairs, scooters, ramps and other equipment lost or damaged in the May and June 2013 storms in Oklahoma. About 200 Oklahomans with mobility issues are expected to benefit over the next 45 days. The program is an extension of a partnership that began earlier this year to install ramps for New Jersey residents affected by Superstorm Sandy. It was also announced earlier this month that Portlight and the American Red Cross have signed a Letter of Agreement to work together in disaster response, in order to improve shelter accessibility and share resources and information.Visit Portlight's wunderground blog to learn more or to donate to this worthy cause.

Figure 2. Portlight volunteers hard at work in Moore, Oklahoma, after the devastating May 20, 2013 tornado.

Jeff Masters

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Baked Alaska: 98° Reading Ties All-Time State Heat Record

Posted by: Dr. Jeff Masters, 5:21 PM GMT on June 19, 2013

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Alaska is a land of extremes, but the weather of the past month has been truly exceptional. An intense ridge of high pressure, part of an extreme jet stream pattern that has become "stuck" in place for many days, is creating the state's hottest heat wave in 44 years this week. Numerous cities in Alaska have recorded their all-time hottest temperatures on record, and according to wunderground's weather historian, Christopher C. Burt, the unofficial 98° measured at B...

85 degree heat

Categories:Heat

Updated: 5:24 PM GMT on June 19, 2013

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TD 2 Slowly Organizing, Headed Towards Veracruz, Mexico

Posted by: Dr. Jeff Masters, 1:50 PM GMT on June 19, 2013

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Tropical Depression Two is slowly spinning west-northwest across the extreme southern Gulf of Mexico--the Bay of Campeche--at 9 mph. The storm has a small area of heavy thunderstorms, as seen on Mexican radar and satellite loops. The thunderstorms are slowly showing more organization this morning, but the storm has little low-level spiral banding, poor upper-level outflow, and is fighting dry air on its west side. However, the Bay of Campeche is a region where the t...

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Tornado Hits Denver International Airport

Posted by: Dr. Jeff Masters, 12:35 AM GMT on June 19, 2013

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Tornadoes are difficult to observe, since they rarely move over instruments that can directly measure their winds. A rare exception occurred on Tuesday, when an EF-1 tornado obligingly ran directly over the weather station at Denver International Airport, which recorded a wind gust of 97 mph. Remarkably, the weather station was not destroyed, and continued to transmit data after the tornado had passed. There was no major damage reported at the airport.

Categories:Tornado

Updated: 12:36 AM GMT on June 19, 2013

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TD 2 Crossing the Yucatan, Bringing Heavy Rains

Posted by: Dr. Jeff Masters, 1:44 PM GMT on June 18, 2013

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Tropical Depression Two is slowly spinning west-northwest across Belize after making landfall late Monday afternoon in southern Belize. The storm is bringing heavy rain to Belize, Northern Guatemala, and Mexico's Yucatan Peninsula, as seen on Belize radar and satellite loops. The center of TD 2 will remain over land all day Tuesday, but TD 2's west-northwest track may be able to bring the storm over the Gulf of Mexico's southern Bay of Campeche on Wednesday--if the ...

Categories:Hurricane

Updated: 3:03 PM GMT on June 18, 2013

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