|Above: MODIS satellite image of Category2 Tropical Cyclone Vayu taken on Wednesday afternoon, June 12, 2019. Image credit: NASA.|
Category 2 Tropical Cyclone Vayu is headed towards a Thursday morning (U.S. EDT) landfall in western India near the Pakistani border, and will bring destructive winds, rains, and storm surge flooding to a portion of India not used to seeing strong cyclones. As of 12Z (8 am EDT) Wednesday, the Joint Typhoon Warning Center placed the center of Vayu about 190 miles west of Mumbai, India. The storm had top winds of 105 mph and a central pressure of 978 mb, and was headed north-northwest at 8 mph. The cyclone had a sprawling circulation, with tropical-storm-force winds extending as far out as 130 - 145 miles along the east side of the storm.
Forecast for Vayu: a hit or a miss?
Vayu is to likely to intensify through Wednesday evening (U.S. EDT), with ample warm water (sea surface temperatures near 30°C or 86°F) along its path, a moist atmosphere, and moderate wind shear of 15-20 knots. The 06Z Wednesday run of the high-resolution HWRF model—among the top models for predicting hurricane intensity—brings Vayu up to minimal Category 3 strength with 115 mph winds on Wednesday afternoon, followed by gradual weakening to Category 2 strength with winds of 95 - 100 mph at landfall near 12Z Thursday.
The Indian Meteorological Department, which has primary responsibility for Vayu forecasts, predicted in its 12Z Wednesday advisory that Vayu would reach the Gujarat coast between Dwarka and Verval on Thursday near 9Z as a Category 2 storm. The IMD warned of a potential storm surge of 1.5 – 2.0 meters (4.9 to 6.5 feet) along parts of the Gujarat coast. The largest surge may occur in the narrow Gulf of Khambhat, more than 100 miles east of Vayu's forecast track (see Figure 1).
Steering currents are expected to collapse on Thursday morning, resulting in a very slow and possibly erratic motion for the storm, and it is possible that the center of the storm may never make landfall, as predicted by the JTWC in their 12Z Wednesday forecast. In either case, torrential rains of 10” or more will likely impact the coast of India, causing dangerous flash flooding. Vayu’s anticipated crawl on or near the coast should lead to weakening due to land interaction, and dry air from the South Asian content will infiltrate Vayu's circulation over time, contributing to the weakening.
Figure 1. Predicted storm surge for Vayu from IMD.
Cyclone history of far western India and southeast Pakistan
Weak tropical cyclones are not uncommon in far western India, but only a handful of Category 2 or stronger equivalents have made landfall in the last few decades. Of the two most recent high-impact landfalls in this area, the first occurred in 1998, when a Category 3 equivalent came ashore on a recurving track that moved head-on across the Gujarat coast near Porbandar on June 10. The near-perpendicular approach contributed to a storm surge of around 5 meters (16 feet).
The 1998 Gujarat cyclone took at least 1063 lives, and relief workers estimated that 10,000 to 14,000 people were missing and likely killed, according to a summary by tropical weather analyst Gary Padgett. Many of those who died were reportedly involved with coastal salt harvesting and did not know of the storm’s approach.
|Figure 2. Satellite image of the 1998 Gujarat cyclone at 1210Z on June 8, 1998. Image credit: NOAA.|
In May 1999, an even stronger cyclone, peaking at high-end Cat 3 strength, followed a very similar track displaced a bit to the northwest. The cyclone made landfall on May 20 in far southeast Pakistan about 70 miles southeast of Karachi. This put the city on the storm's weaker northwest side (winds in Karachi were only 44 mph), while the cyclone dumped heavy rains and lashed parts of extreme southern Pakistan and far western India with high winds and storm surge.
|Figure 3. Satellite image of the 1999 Pakistan cyclone at 1027Z on May 20, 1999. Image credit: NOAA.|
Only one death was reported in India from the May 1999 cyclone. In Pakistan, 400 bodies were recovered, and the national government reported that some 5800 other people were missing and presumed killed. “Although the Pakistani government had issued warnings for this storm, no large-scale evacuations were ordered,” said NOAA’s Hurricane Research Division in a 15th anniversary retrospective on this cyclone.
Bob Henson co-wrote this post.