The short version
- Bangkok officials declared a disaster zone after low-pressure systems caused waist-high flooding, though rainfall has recently ceased as the system moved northwest.
- Hurricane Nolo passed south of Hawaii’s Big Island with category 2 strength, delivering over 530mm of rain that raised concerns about mudslides before moving westward.
- Hurricane Polo is forecast to strike Baja California as a category 2 storm, bringing dangerous storm surges and intense rainfall expected to cause life-threatening flooding.
Authorities in Bangkok declared the Thai capital a disaster zone late last week following severe inundation that left streets submerged in water reaching waist height. The crisis was driven by an active low-pressure cell situated over central Thailand, which generated continuous heavy rainfall and thunderstorms across the metropolitan area and surrounding regions. This declaration marks a significant escalation in the local response to the weather event, reflecting the severity of the infrastructure challenges faced by residents and municipal services during the peak of the flooding.
The meteorological conditions leading to this outcome began early Thursday when a weak low-pressure area traveled northwestward up the Gulf of Thailand. By Friday morning, this system had settled over central Thailand and remained largely stationary for two days. This stagnation allowed unrelenting downpours to persist over Bangkok and nearby areas without relief. The lack of movement in the weather system meant that rain fell continuously on the same saturated ground, exacerbating drainage issues and leading to the widespread accumulation of floodwater observed throughout the city.
Rainfall totals recorded during this period were substantial, highlighting the intensity of the event. A weather station located near Prachin Buri, situated just northeast of the capital, logged 213.5 millimeters of precipitation within a single 24-hour window between Friday and Saturday evening. To provide context for this volume, London receives an average of only 585 millimeters of rain across an entire year. Such concentrated rainfall in a short timeframe overwhelmed local drainage capacities, contributing directly to the depth and spread of the flooding that prompted the disaster zone designation.
Fortunately, the immediate threat to Bangkok has diminished as the center of the low-pressure cell shifted northwestward on Sunday. This movement brought an end to the torrential rainfall that had plagued the capital for several days. While the water levels remain a concern for cleanup and recovery efforts, the cessation of heavy rain allows officials to focus on assessing damage and restoring normalcy to the affected areas. The shift in weather patterns suggests a temporary reprieve from the acute flooding crisis that defined the latter part of the week.
Meanwhile, in the central Pacific, residents of Hawaii’s Big Island faced significant threats from Hurricane Nolo over the weekend. The system initially approached the archipelago early last week, bringing heavy rainfall starting around Tuesday evening. By the early hours of Saturday, Nolo had intensified into a category 2 hurricane, with sustained wind speeds ranging from 85 to 90 knots, equivalent to 98 to 104 miles per hour. At its closest point, the storm was situated approximately 145 miles, or 233 kilometers, south of the Big Island.
Although strong winds were a primary concern, the vast quantity of rainfall associated with Nolo raised serious fears regarding flooding and mudslides on the island. Weather stations in the northeast portion of the island recorded over 530 millimeters of rain since impacts began late on Tuesday, September 22. This volume of precipitation poses a severe risk to stability in volcanic terrain, where saturated soils can easily give way. The combination of wind and water created a complex hazard environment for emergency responders and residents alike.
Nolo has since propagated westward, moving away from Hawaii. Forecasts indicate that the storm is expected to peak in intensity on Monday, September 28, with predictions suggesting it could achieve category 4 status. As it moves further into the Pacific, the immediate danger to the Hawaiian islands recedes, but the storm remains a powerful force in the region. Meteorologists are closely monitoring its trajectory and strength as it continues to evolve in the open ocean.
Farther east in the Pacific Ocean, Hurricane Polo presents another significant weather event. The storm is forecast to make landfall on the Baja California peninsula late on Monday, September 28. Although Polo was previously a category 5 hurricane, it is expected to downgrade to category 2 by the time it reaches land, with sustained winds of 96 to 110 miles per hour. A hurricane warning has been issued for coastal regions due to the risk of storm surge, particularly where winds are blowing onshore.
In addition to wind and surge risks, Polo will bring intense downpours as it traverses the peninsula. Rainfall totals are expected to range from 100 to 200 millimeters, with local amounts potentially reaching up to 250 millimeters. The bulk of this precipitation is anticipated to fall within a 12-hour period, creating conditions conducive to life-threatening flooding and mudslides. After crossing Baja California, the storm is expected to continue weakening as it propagates northeastward across the Sonora region in Mexico.
Sources behind this briefing
Go to the original reporting
- The Guardian US↗Thai downpours shift north-westwards after Bangkok declared a disaster zone
