TropicalAnalystwx13's WunderBlog

Invest 93E likely to become Boris; Atlantic development possible

By: TropicalAnalystwx13, 5:06 AM GMT on May 31, 2014

The 2014 Pacific hurricane season began on May 15, and already we've witnessed a historic tropical cyclone. Hurricane Amanda--which formed on May 22--was able to become the second-earliest major hurricane (a storm that ranks as a Category 3 or higher on the Saffir-Simpson hurricane wind scale) on record (behind 2012's Hurricane Bud), the earliest Category 4 hurricane on record (beating 2001's Hurricane Adolph), the strongest May tropical cyclone on record in the East Pacific (beating 2001's Hurricane Adolph), and the 3rd fastest-intensifying hurricane on record in the East Pacific (57 millibar drop, 80 mph increase in winds in 24 hours). In addition, the storm accrued 18.5775 units of Accumulated Cyclone Energy, making it the single highest ACE-producing cyclone during the month of May in the East Pacific and pushing the monthly ACE value for May to its highest point on record. For perspective, this is roughly 619% of the climatological average (3 units), 51% of the total ACE accumulated by the 2013 Atlantic hurricane season, and roughly 14% of the average seasonal ACE value in the East the first month of the season. Though Amanda never made landfall, the outer peripheries of the storm were able to deliver heavy rainfall to the coastal sections of southwestern Mexico. At least 3 people have been killed by the storm.

Figure 1. A visible satellite image of Hurricane Amanda, taken at 1445z. At this time, maximum sustained winds were estimated at 155 mph. Credit: NASA

Invest 93E Likely To Become Boris
With Amanda but a remnant area of low pressure now, the focus shifts to a new area of disturbed weather located south of the Gulf of Tehuantepec. This disturbance -- just declared Invest 93E by the National Hurricane Center -- remains disorganized at the present time, with a large area of shower and thunderstorm activity and a broad center of circulation. Over the coming days, 93E is expected to increase in organization and is likely to become Tropical Storm Boris. A look at 250mb maps reveals that the system is located in a region of light to moderate wind shear, with anticyclonic flow aloft. This favorable environment is expected to remain in place as the storm drifts slowly northward. In addition, it is embedded within a region of high precipitable water, suggesting that dry air will not be much of an issue. At this time, the National Hurricane Center gives 93E a Medium chance, 30%, of becoming a tropical cyclone over the next 48 hours, and a High chance, 70%, of becoming a tropical cyclone over the next 120 hours. I think these chances are higher, near 50% and 90%, respectively. If this system were to form, it would likely move northward towards a weakness across the Gulf of Mexico. As far as ultimate intensity, the broad size of the system may limit the chances for rapid intensification, but model consensus suggests a strong tropical storm or Category 1 hurricane is possible at peak. Regardless of development, torrential rains are likely for much of Central America, and totals in isolated locations could exceed a foot and a half; flash flooding and numerous mudslides appear likely. Remember, it doesn't take a powerful hurricane for there to be a significant number of deaths, injuries, and widespread damage.

Figure 2. Infrared satellite imagery of Invest 93E. Credit: NOAA

Atlantic Development Possible
The 2014 Atlantic hurricane season begins on Sunday -- June 1 -- and already the potential for the first tropical cyclone of the year exists, centered in the southern Gulf of Mexico as we head into next week. The setup is complicated, with a cutoff low currently positioned over the southern United States likely to fill in and leave behind an inverted trough stretching from the central Gulf of Mexico into the eastern Pacific, in a region with preexisting cyclonic rotation. Off the bat, there are concerns with how favorable conditions will be: if 93E develops into a tropical cyclone, its resultant outflow would likely increase upper-level winds across the region. The GFS suggests that once the East Pacific cyclone moves ashore and its energy is absorbed into a developing area of low pressure in the southern Gulf wind shear will lower some, but it is likely to remain unfavorable for significant development. In the latest run, the model takes a weak tropical storm towards the coastline of Florida. The ECMWF model seems more reasonable, with a weak, sheared area of low pressure never really consolidating into anything worth noting. It is important to keep in mind that, regardless of development, heavy rainfall is expected to spread into the Southeast, where flooding will be possible. At this point, I assess the chances of development in the Atlantic next week near 20%.

Figure 3. Total accumulated precipitation through the next 192 hours (May 31-June 8) via the 0z GFS.

I should have a new blog tomorrow--but don't hold that to me,


Tropical Cyclones of 2014 Tropical Weather

Updated: 9:04 PM GMT on May 31, 2014


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Small town USA guy. Politics nerd. Soccer fan. Interested in eyewalls, deformation zones, and hook echos.

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