Worst Flooding Still to Come in Philippines from Koppu; Champi Now a Super Typhoon

Although it has weakened to Category 1 strength since making landfall, Typhoon Koppu continues to hold high potential for catastrophic multi-day rainfall in the large Philippines island of Luzon. Koppu edged into the east-coast province of Aurora around 1:00 am Sunday local time as a super typhoon, packing top winds estimated by the Joint Typhoon Warning Center (JTWC) at 150 mph. Fortunately, this part of Luzon is fairly sparsely populated, though two fatalities had been reported by Sunday evening local time. Tree and structural damage and power outages are widespread. At least 9 million residents of Luzon--close to 10 percent of the population of the Philippines--were without power as of Sunday afternoon local time (midnight Saturday night EDT), according to data from the Philippines National Disaster Risk and Reduction Management Council. (Thanks to Nick Wiltgen at the Weather Channel for this statistic.) At 11:00 pm local time Sunday (11:00 am EDT), Koppu was located about 140 miles north-northwest of Manila along the west coast of Luzon. Koppu is known as Lando in the Philippines, which maintains its own naming system for tropical cyclones.

Storm chaser James Reynolds (@EarthUncutTV on Twitter) encountered very high water levels on the Pampanga River north of Cabanatuan, a city of about 270,000 in central Luzon. The embedded YouTube clip at the bottom of this point includes video collected by Reynolds near Cabanatuan and during landfall from the small city of Maddela, just inland from Luzan’s east coast.


Figure 1. MODIS image of Typhoon Koppu over Luzon Island in the Philippines as seen from NASA's Terra satellite on Sunday, October 18, 2015. At the time, Koppu was a Category 2 storm with 105 mph winds. Image credit: NASA.


Figure 2. A man looks at the rising water level of the Magat River caused by continuous rains of Typhoon Koppu at Bayombong, Nueva Viscaya, Philippines, on Sunday, October 18, 2015. Koppu wrecked houses, tore down trees, and unleashed landslides and floods, forcing thousands to flee as it pummeled the northern Philippines on Sunday. Image credit: STR/AFP/Getty Images.


Torrential rains to grip Luzon for several days
The projected track of Koppu is close to a worst-case scenario for catastrophic rainfall across northern Luzon, home to more than 10 million people. Steering currents are collapsing, and the typhoon will be caught in the midst of a broad upper-level ridge, with little to move it out to sea anytime soon. Models agree that the circulation will inch northward over the next 3 to 4 days, either hugging the northwest coast of Luzon or moving along the spine of the island. 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 if the center remains just offshore. The 06Z and 12Z Sunday runs of the GFS model keeps the center of Koppu near Luzon until early Friday local time, while the ECMWF pulls Koppu away from the island by Thursday and the UKMET by Wednesday. At a minimum, we can expect widespread storm totals of one to two feet of rain across much of northern Luzon. High-resolution output from the GFS and ECMWF suggest that a few localized multi-day totals in or beyond the 40” - 50” range are conceivable. Widespread flooding and mudslides are virtually certain, and major agricultural damage can be expected as well. It appears the heaviest rains will stay north of Manila, but Koppu could still end up as one of the most costly natural disasters in Philippine history if the predicted rains materialize.


Figure 3. Weak steering flow will be surrounding Typhoon Koppu for several days, exacerbating the risk of heavy rain over the northern Philippines. Shown in this WunderMap image is the flow at 200 mb (about 40,000 feet), labeled in knots, predicted by the 12Z Sunday run of the GFS model for 18Z Tuesday (2 a.m. local time Wednesday).


Figure 4. Five-day precipitation totals (in inches) predicted by the 12Z Sunday run of the GFS model. Localized totals could be much higher than depicted in this coarse-resolution graphic. Image credit: NWS/NCEP.


Some of the heaviest rain may fall in and near 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.

For reference, below are the global 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 5. Infrared satellite image of Super Typhoon Champi, collected at 1630Z (12:30 pm EDT) Sunday, October 18, 2015. Image credit: CIMMS/SSEC/University of Wisconsin.

Another day, another super typhoon: Champi
The Pacific’s relentless tropical season of 2015 continues to amaze. On Saturday, Koppu became the 19th hurricane or typhoon north of the equator to reach Category 4 strength, a new seasonal record for the Northern Hemisphere. On Sunday, Super Typhoon Champi pushed that record to 20, as it bolted from top sustained winds of 115 mph at 0000 GMT Sunday to 150 mph at 1200 GMT Sunday. (Only one of those Category 4 and 5 storms--Hurricane Joaquin--came from the Atlantic.) Champi is the season’s ninth super typhoon--impressive, but still short of the Northwest Pacific record of 11 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). Late Sunday night, Champi was moving slowly northward in the open Northwest Pacific, more than 300 miles south-southwest of Iwo Jima. Champi is forecast by the JTWC to reach Category 5 status by Monday; it should recurve near Iwo Jima as a weakening but still powerful typhoon on Wednesday.

92L running aground in Mexico
Invest 92L should be dissipating soon as it moves onto the southern shores of the Bay of Campeche. Moisture flowing the vicinity of 92L will help fuel heavy rains across Texas later this week, and the decaying system may also feed the development of Invest 97E, just south of the Gulf of Tehuantepec. 97E will track northwest parallel to Mexico’s Pacific coast for the next several days, far enough offshore to allow for strengthening. The National Hurricane Center gives 97E a 40 percent chance of development by Tuesday and an 80 percent chance by Friday. Further west, newly designated Hurricane Olaf will churn harmlessly well out to sea, possibly reaching Category 3 strength by Tuesday before it begins to weaken later in the week.

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.