Koppu Kills 12, Dumps 30+ Inches of Rain on Philippines; Olaf Hits Category 3

Tropical Storm Koppu has weakened below typhoon strength, but is still bringing dangerous torrential rains to much of the Philippines' Luzon Island as the storm drifts north-northeastwards at 4 mph along the west coast of the island. Koppu, which is known as "Lando" in the Philippines, hit the east-coast province of Aurora around 1:00 am Sunday local time at peak strength, with sustained winds of 150 mph and a central pressure of 920 mb. Fortunately, that part of Luzon is fairly sparsely populated; the death toll from the typhoon stood at a relatively low twelve people on Monday morning. However, damage was reported to nearly 100% of the houses and infrastructure in the city of Casiguran (population 27,000), near where the storm made landfall, and some towns are still cut off from communications. At least 9 million residents of Luzon--close to 10 percent of the population of the Philippines--were without power at the height of the storm on Sunday afternoon local time (midnight Saturday night EDT), according to data from the Philippines National Disaster Risk and Reduction Management Council.


Figure 1. MODIS image of Typhoon Koppu, centered along the west coast of Luzon Island in the Philippines, as seen from NASA's Terra satellite on Monday, October 19, 2015 at 03:05 UTC. At the time, Koppu was a Category 1 storm with 80 mph winds. Image credit: NASA.


Figure 2. A resident carries his rescued piglet near flood-inundated houses at a village in Santa Rosa town, Nueva Ecija province, north of Manila on October 19, 2015, a day after Typhoon Koppu hit Aurora province. Image credit: TED ALJIBE/AFP/Getty Images.

Torrential rains to grip Luzon for several days
Extreme rainfall and flooding remain the main threat from Koppu. Steering currents have collapsed, and the typhoon will move very slowly to the northeast at less than 5 mph over northern Luzon for the next 2 - 4 days. Although Koppu will continue to deteriorate as its center remains over or near land, its broad, strong circulation will keep pulling deep moisture into the island, where upslope flow against higher terrain will squeeze out mammoth amounts of rain. Even a tropical depression can produce enormous rains if it’s moving slowly, especially when positioned near high terrain, and Koppu should maintain at least tropical storm strength the next two days. At a minimum, we can expect widespread storm totals of one to two feet of rain across much of northern Luzon. Multi-day rainfall totals of over two feet will result in widespread flooding and mudslides, and major agricultural damage can be expected as well. It appears the heaviest rains will stay north of the Philippines' most heavily populated region--the capital of Manila--but Koppu could still end up as one of the top-five most costly natural disasters in Philippine history.

Torrential rains in excess of 20" have already hit the city of Baguio, a regional center with about 300,000 residents that’s popular among visitors for its relatively cool climate. Located at an elevation of roughly 5000 feet, but less than 20 miles from Luzon’s west coast, Baguio is highly vulnerable to moist westerly winds being forced upslope. A typhoon in July 1911 dumped more than 2,200 millimeters (87 inches) of rain on the city in less than four days. In September 2015, Typhoon Goni brought more than 700 millimeters (28 inches) of rain to Baguio, even without making a direct hit on the Philippines, as noted by weather.com. Baguio received 6.34" of rain from Koppu in the 24 hours ending at 00 UTC October 19, 2015, then another 15.94" in the twelve hours ending at 12 UTC (8 am EDT) Monday. Another 11.14" fell in the six hours ending at 18 UTC, for a 42-hour rainfall total of 33.42" (849 mm.) Monday morning rainfall forecasts from the HWRF model were projecting another 1 - 2 feet of rain over western Luzon Island from Koppu.

For reference, below are the global and hemisphere records for heaviest rainfall observed in various time periods, as certified by the World Meteorological Organization and archived by Arizona State University.

24 hours: 1.825m (71.8"), January 7-8, 1966, Foc-Foc, La Réunion
48 hours: 2.493m (98.15"), June 15-16, 1995, Cherrapunji, India
72 hours: 3.930m (154.72"), February 24-26, 2007, Cratère Commerson, La Réunion
96 hours: 4.936m (194.33"), February 24-27, 2007, Cratère Commerson, La Réunion


Figure 3. MODIS image of Typhoon Champi as seen from NASA's Terra satellite on Monday, October 19, 2015 at 01:25 UTC. At the time, Champi was a Category 4 storm with 135 mph winds. Image credit: NASA.

Typhoon Champi headed towards Iwo Jima
The Pacific’s relentless tropical season of 2015 continues to amaze. On Sunday, Super Typhoon Champi became the Northern Hemisphere's record-setting twentieth Category 4 or stronger tropical cyclone of 2015 (previous record: eighteen in 2004, according to wunderblogger Dr. Phil Klotzbach.) Only one of those twenty Category 4 and 5 storms--Hurricane Joaquin--came from the Atlantic. Champi is the season’s eighth super typhoon, with winds of at least 150 mph--impressive, but still short of the Northwest Pacific record of eleven super typhoons set in 1965 and matched in 1997.

The only land areas likely to be affected by Champi are Japan’s sparsely populated Volcano Islands, including Iwo Jima (Iwo To). Champi has weakened to a Categery 3 storm, and is forecast by the Joint Typhoon Warning Center (JTWC) to continue to steadily weaken this week, passing very near Iwo Jima as a Category 2 storm near 00 UTC Thursday.


Figure 4. Latest satellite image of Hurricane Olaf.

Eastern Pacific's Hurricane Olaf sets a new record
Hurricane Olaf intensified into a major Category 3 hurricane on Monday at 11 am EDT in the waters about 1350 miles east-southeast of Hawaii, becoming the tenth hurricane and eighth major hurricane of this very busy Eastern Pacific hurricane season. Olaf became a major hurricane unusually far to the south--at 9.9°N latitude, making it the most southerly major hurricane ever observed in the Eastern Pacific since reliable records began in 1971. This year now ties with 2014 and 1992 for the most number of major Eastern Pacific major hurricanes (east of 140°W) in a season--eight. An average Eastern Pacific hurricane season sees 15 named storms, 8 hurricanes, and 3 intense hurricanes, and we have already had 15 named storms, 10 hurricanes, and 8 intense hurricanes so far in 2015. This is the second consecutive year with unusually heavy activity in the Eastern Pacific--in 2014, the basin had 20 named storms, 13 hurricanes, and 8 intense hurricanes, making it the busiest season since 1992, which set records for total number of named storms (24), hurricanes (14), and intense hurricanes (8). It has also been a hyperactive year for hurricanes in the Central Pacific, between 140°W and 180°W. So far in 2015, eight named storms have formed in the Central Pacific, setting a new record for tropical cyclone activity in that basin. According to wunderblogger Dr. Phil Klotzbach, prior to 2015, the previous record for named storms in the North Central Pacific for an entire season was four, set in 1982. This year's record activity in both the Eastern Pacific and Central Pacific has been due to unusually low wind shear and record-warm ocean temperatures caused by the strong El Niño event underway.

Olaf is likely to turn to the north by this weekend well east of Hawaii, but the long-term fate of the storm remains unclear; Hawaii may need to be concerned with Olaf next week.

Invest 97E to bring heavy rains to Mexico's Pacific coast
The Pacific coast of Mexico needs to be concerned with Invest 97E, and area of heavy thunderstorms extending from near the coast of Guatemala westwards along the south coast of Mexico. 97E will track northwestwards to west-northwestwards parallel to Mexico’s Pacific coast for the next several days, far enough offshore to allow for strengthening. In their 8 am EDT Monday Tropical Weather Outlook, the National Hurricane Center gave 97E 2-day and 5-day odds of development of 50% and 80%, respectively.

Low odds of development in the Gulf of Mexico
An area of showers and thunderstorms extending from the northwestern Caribbean Sea through Mexico's Yucatan Peninsula at 8 am EDT Monday was associated with a weak area of low pressure. This low will move slowly west-northwest at about 5 mph, and may emerge over the southern Gulf of Mexico's Bay of Campeche by Wednesday. The disturbance's proximity to land, and presence of 30 knots of wind shear, make development unlikely. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave the disturbance 2-day and 5-day odds of development of 0% and 10%, respectively. Moisture from the disturbance is likely to spread northwards Wednesday through Friday across the Southern Plains and interact with an upper level low pressure system, bringing heavy rains. Eastern New Mexico, the Texas Panhandle, and the Oklahoma Panhandle could see widespread flooding Wednesday and Thursday, and the flood threat increases late Friday through Sunday for eastern Texas.

Wunderblogger Steve Gregory has an update on El Niño in his Monday afternoon post, Strong Warm-Up on the Way as El Niño Flow Pattern Becomes Firmly Entrenched.

Jeff Masters and Bob Henson


Video 1. Video compilation from James Reynolds of wind damage and flooding associated with Typhoon Koppu, posted on Sunday, October 18, 2015. Image credit: Earth Uncut TV.