Rare January Depression in Central Pacific; Atlantic Subtropical Storm Next Week?

After a record-smashing hurricane season in 2015, the Central Pacific is off to a record-early start with Tropical Depression One-C, which formed on Thursday morning in the waters about 1,500 miles southwest of Honolulu, Hawaii. According to NHC hurricane specialist Eric Blake, TD 1-C's genesis date of January 7 breaks by six days the record for earliest formation of a tropical cyclone in the Central Pacific set by Tropical Storm Winona on January 13, 1989. TD 1-C was able to form because of an unusual wind pattern near the equator associated with El Niño--a burst of westerly winds near the equator, when combined with a more typical east-to-west flow of trade winds farther to the north helped create an area of counter-clockwise spin. A sprawling region of showers and thunderstorms associated with TD 1-C at roughly 4°N and 171°W is located squarely atop some of the warmest waters associated with the powerful El Niño event now under way--29.5°C (85°F). Weak steering currents make it difficult to judge TD-1C's future path, although a slow motion northwestwards appears likely over the next couple of days.

The GFS and ECMWF models support the idea of TD 1-C attaining tropical storm strength between now and Saturday, January 9. If so, it will be named Tropical Storm Pali. Only two tropical storms have been recorded in January across the Central and Northeast Pacific (the region north of the equator and east of the International Date Line) since reliable records began in 1949. The first one was 1989’s Winona, which attained tropical storm strength on January 13 and peaked with sustained winds of 55 knots. In 1992, Ekeka was christened as a tropical storm on January 28 well west of Hawaii before becoming a rare February hurricane, with Category 3 winds reaching 115 mph.


Figure 1. Latest satellite image of Invest TD 1-C.

A spin that crossed the equator
Remarkably, TD 1-C appears to have roots on the other side of the equator! Last week, a short-lived tropical depression (TD 9-C) originated as the northern member of a pair of twin cyclones. Such sets of twins usually straddle the equatorial Pacific, with the northern member rotating counterclockwise and the southern member clockwise. In between, these circulations produce a zone of low-level westerly winds that can act to reinforce or intensify El Niño conditions across the equatorial Pacific. Last week’s twin cyclones were displaced so far south that the northern member (eventually to become TD 9-C) was located just south of the equator, close to the International Date Line, with a powerful westerly wind burst in between the cyclones. On the south side of this wind burst, Severe Tropical Cyclone Ula has been threading its way around several Southwest Pacific islands since becoming a depression on December 29 and strengthening to a Category 3 cyclone by January 1. The Joint Typhoon Warning Center projects that Ula will continue its winding path well south of Fiji over the next few days, remaining at weak to middling tropical-storm strength

An animated visible satellite loop created by Dan Lindsey (CIRA/Colorado State University), using data from the Himiwari-8 satellite, clearly shows the counterclockwise rotation as the northern cyclone approached the equator on December 28. Drifting northward, it gained enough strength to be christened TD 9-C late on December 30. Located at 2.8°N, it was the lowest-latitude system on record to become a tropical cyclone in the Western Hemisphere, according to Michael Lowry (The Weather Channel). TD 9-C’s circulation dissipated late on January 1, but the large field of moisture associated with it remained, providing fertile ground for the development of TD 1-C this week.


Figure 2. Left: Streamers reveal the twin circulations along and south of the equator near the International Date Line on December 27, 2015, with a large area of strong westerly winds in between. Right: Infrared satellite imagery shows the large field of moisture associated with the northern circulation, which went on to become Tropical Depression 9. Image credit: (left) courtesy Mark Lander, University of Guam.

Tropical cyclones developing near the equator are very rare, since the Coriolis force (a function of Earth’s spin) does not force areas of low pressure to rotate in either direction at 0° latitude. But tropical cyclones near the equator are not unprecedented. In 2004, the center of low pressure that eventually became Severe Cyclonic Storm Agni in the Northwest Pacific briefly moved south of the equator. Agni became a depression at 1.5°N, tying with Tropical Storm Vamei (2001) as having the most equatorward development of any tropical cyclone on record. The recent strong westerly wind burst between the Pacific’s twin cyclones no doubt helped give TD 9-C some of the spin that it would have otherwise been unable to gain due to its equatorial location.

Elsewhere in the tropics (January edition)
Unusual activity has been percolating in the Atlantic as well. On Tuesday, Brazil’s Navy Hydrographic Center identified a subtropical depression east of Rio de Janeiro. It was briefly classified as a tropical depression on Wednesday, although both designations had been removed in the center's 12Z analysis on Thursday morning. It was once thought that tropical cyclones never formed in the South Atlantic, but Category 1 Hurricane Catarina shocked Brazil--and the world of tropical meteorology--when it crashed into the coast of Brazil’s Santa Catarina province on March 27, 2004, causing more than $300 million in damage. Forecasters are now tracking down subtropical systems in the South Atlantic about once per year, on average, though tropical storms (those with fairly symmetric warm cores) are much less common. Jon Erdman and Chris Dolce have more background on this South Atlantic event in a Wednesday article at weather.com.

There is also potential for a large and powerful January cyclone to evolve over the North Atlantic subtropics between Bermuda and the Azores Islands early next week, as consistently predicted by the GFS and ECMWF models. This cyclone is now several hundred miles northeast of the Bahamas, strengthening as an non-tropical system ahead of a subtropical jet stream typical of El Niño winters. A strong upper-level ridge will develop to the north of the cyclone as it races east and then southeast. Phase-space diagrams from Florida State University show this system taking on subtropical characteristics (asymmetric warm core) this weekend and early next week. Upper-level winds will remain strong in the vicinity of this system, and ocean temperatures will be a marginal 24-25°C (75-77°F), suggesting that any potential development would be subtropical rather than tropical. If this storm were to get a name, it would be "Alex." The Atlantic’s most recent tropical cyclone during January was Tropical Storm Zeta, which served as the closing act of the blockbuster 2005 hurricane season. Zeta formed on December 30 and survived until January 7, 2006, west of the Cape Verde Islands.

Bob Henson


Figure 3. A classic comma-shaped extratropical cyclone, located northeast of the Bahamas at 1630Z (11:30 am EST) on Thursday, January 7, 2016, has some potential for subtropical development as it moves into the central Atlantic early next week. Image credit: NASA Earth Science Office and NOAA.

Portlight's Paul Timmons to serve as Red Cross Disability Integration Coordinator
The Portlight.org disaster relief charity, founded and staffed by members of the wunderground community, has received some well-earned recognition from the Red Cross, which announced on Dec. 16 that Paul Timmons of Portlight Strategies will serve as disability integration coordinator for the national provider of emergency assistance and disaster relief. Portlight Strategies, based in Charleston, S.C., is the only known national and international disaster relief agency that focuses on serving people with disabilities.

“I’m super excited that Paul has agreed to do this because I think that he’s got a tremendous amount of credibility with the disability community and I think he speaks disaster,” said Brad Kieserman, vice president of Red Cross Disaster Operations and Logistics, in an interview with newmobility.com.

Timmons will be responsible for building disability infrastructure within the Red Cross, including building relationships, improving service delivery and implementing disability specific training. “Kieserman’s embracing of our interests and his embracing of the Red Cross getting our issues right has just been a game changer,” Timmons said. “It’s allowed us to get the conversation out of the American Red Cross headquarters and out into the field where it should be.“

According to Timmons, fixing the divide between the Red Cross and the disability community will require constant community organizing. “We can’t train our way out of this,” he said. “We can’t meet our way out of this. We can’t conference call our way out of this. We have to organize our way out of this.” He encourages the disability community to stay involved in the process.

Because of serious issues such as Red Cross shelters not being accessible, there is tension between the Red Cross and the disability community admits Kieserman, but he’s optimistic the situation can be fixed. “I hope that going into the new year with Paul and Portlight now under contract with the Red Cross, and with the Red Cross committing to increased emphasis and focus on disability integration issues, we will have the opportunity to turn the corner,” he said.

You can check out Portlight's latest activities and donate to Portlight's disaster relief fund at the portlight.org website.

Jeff Masters