The Eastern Pacific is Sizzling; Nothing Cooking in the Atlantic

The Eastern Pacific, which got off to its second slowest start on record on July 2 when Tropical Storm Agatha formed, is in the midst of an extraordinary period of July activity, thanks to favorable genesis conditions created by the presence of the Madden-Julian Oscillation (MJO.) Hurricane Blas, which reached Category 4 strength last week, but has since become post-tropical, has now been replaced by Hurricane Celia, which formed on Friday morning. Celia is expected to become a Category 2 hurricane late Monday before reaching cooler waters less than 26°C (79°F). These cooler waters that Celia will encounter beginning on Tuesday should induce a long-term weakening trend. Long-range runs from the GFS and European models on Monday morning predicted that a weak Tropical Storm Celia would pass within 500 miles of the Hawaiian Islands on Monday July 18, potentially giving the islands some high surf and heavy rains. However, it is too early to assess the odds of this happening.


Figure 1. VIIRS visible satellite image of ex-Hurricane Blas, Hurricane Celia, and Invest 97E taken on Sunday afternoon, July 10, 2016. Image credit: NASA.


Figure 2. Wind forecast for 2 am EDT Sunday, July 17, 2016, from the 8 pm EDT Sunday, July 10, 2016 forecast of the GFS model. The GFS model was predicting that there would be three simultaneous named storms in the Eastern Pacific. Image created using our wundermap with the "Model Data" layer turned on.

Darby and Estelle on the way
Tropical Storm Darby is expected to join Celia soon, as Monday morning satellite imagery showed that an area of disturbed weather located about 350 miles south-southwest of Manzanillo, Mexico (97E) was getting close to tropical depression status. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave 97E 2-day and 5-day odds of development of 80% and 90%, respectively.

Tropical Storm Estelle is also likely on the way--both the European and GFS models show an area of disturbed weather will develop several hundred miles southwest of the coast of Mexico by the end of this week, and this disturbance has the potential to intensify into a tropical storm over the weekend. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave this future disturbance 2-day and 5-day odds of development of 0% and 20%, respectively. These potential future Darby and Estelle storms are expected to follow a path similar to Agatha, Blas, and Celia--generally west to west-northwest, away from Mexico. If the Eastern Pacific manages to spit out a Tropical Storm Frank before the end of the month--which is quite possible, given the long-range forecasts of the continued presence of the MJO over the Eastern Pacific into the end of July--this would give us six named storms for the month, which would approach the July record (from 1985) of seven named storms forming in the Eastern Pacific, according to NHC hurricane scientist Eric Blake.


Figure 3. The tropical Atlantic is dominated by dry air and dust from the Saharan Air Layer (SAL), seen in orange colors in this satellite analysis from the Meteosat bird. Continued outbreaks of dust and dry air from the SAL are expected over the tropical Atlantic into next week, according to recent model runs. Image credit: University of Wisconsin/CIMSS.

Nothing cooking in the Atlantic except African dust
As is usually the case when the Eastern Pacific is active, the Atlantic is quiet. This anti-correlation in activity occurs because rising air over the tropical Eastern Pacific typically creates a compensating area of sinking air over the tropical Atlantic. This sinking air creates surface high pressure and dry weather--the antithesis of conditions needed for tropical cyclone formation. There are no tropical cyclone threat areas in the Atlantic to discuss today, and none of the reliable models for tropical cyclone formation is predicting development during the coming five days. I'd be surprised to see a serious threat area develop in the Atlantic until the Eastern Pacific's spasm of activity slows down.


Figure 4. A woman cleans mud and debris after flooding in China's Fujian Province on July 10, 2016 after Tropical Storm Nepartak's landfall. Image credit: Zhang Guojun/XInhua via AP.

Typhoon Nepartak's aftermath: 12 dead, $200 million in damage
Typhoon Nepartak sloshed ashore as a weakening tropical storm over China's Fujian Province on Saturday, July 9, bringing heavy rains of 4 - 8" in this region of China closest to Taiwan. The resulting flooding is being blamed for 9 deaths in China. Eighteen people are missing, and damage is estimated at $135 million. In Taiwan, where Nepartak powered ashore on July 7 as a Category 4 super typhoon with top sustained winds of 150 mph, three deaths are being blamed on the storm, with over $62 million in damage.

Jeff Masters