The Historical Impacts of Super Typhoon Bavi
Jared Young - Senior Meteorologist/Marketing Assistant

Earlier this month, Super Typhoon Bavi developed quickly into a historical cyclone over the W’rn Pacific Ocean. The system created widespread destruction across Guam and the Northern Mariana Islands as it passed directly over Rota on the 06^th with sustained winds reaching approximately 156 knots (180 mph). This system marks the strongest ever to make landfall over Rota. Bavi then barreled directly towards Taiwan, the N’rn Philippines and S’rn Japan through the rest of the week, remaining a formidable system until continuing inland over E’rn China between the 11^th and 12^th.

Figure 1: Infrared satellite imagery of Super Typhoon Bavi prior to near landfall over Rota. Image courtesy of GEO-KOMPSAT satellite (CSU/CIRA & KMA/NMSC). 

Bavi initially was alerted as a new invest on June 25^th just to the east of the Marshall Islands. Warm sea surface temperatures (SSTs) approximately 2 degrees Celsius higher than normal, in addition to low vertical wind shear, allowed for a favorable environment for cyclogenesis through the next several days as the system made W’ward progress towards Guam and the Northern Mariana Islands. These warm SSTs and low vertical wind shear both correlate with the current El Niño trends across the Pacific Ocean.

Figure 2: Estimated Tropical Cyclone intensity of Bavi between July 01 and July 10. Chart is courtesy of Cooperative Institute for Meteorological Satellite Studies

On July 01^st, the storm intensified into a tropical depression, with the system then strengthening more notably thereafter. As shown in Figure 2 above, Bavi was able to undergo rapid intensification from a strong tropical storm into a Category 5 super typhoon in a little over 24 hours between the 02^nd and 03^rd. Eyewall replacement cycles which occurred as the system approached Rota through the morning of the 06^th are responsible for the slight fluctuations in the strength of Bavi as shown in Figure 2. A strengthening in the eyewall occurred just prior to the system’s arrival to Rota early on the 06^th, causing winds to ramp up even stronger as the system moved across the Northern Mariana Islands. Bavi also brought heavy rainfall and enhanced storm surge to Guam as it passed to the north, resulting in catastrophic flooding to the island.

Bavi then remained as a Super Typhoon while lifting WNW’ward through the later hours of the 06^th into the 07^th, prior to finally weakening during final approach to the N’rn Phillipines, Taiwan and S’rn Japan through July 10^th and 11th. While the system weakened, Bavi also expanded, generating widespread flooding and high winds across these regions before making landfall in E’rn China later on the 11^th and weakening more notably thereafter.

In order to keep our captains informed of any possible tropical development in the West Pacific (as well as other regions of the world), WRI offers complimentary tropical summaries and alerts to clients who utilize our customized forecasts and/or SeaWeather platform. These alerts can give plenty of advance notice to ensure that you and your vessel remain out of harms way from tropical cyclones around the globe. Contact our office to learn more about how you can stay up to date on any current tropical development in your region of the world.

Transiting the Alaskan Fjords
Maxwell Gallo, Senior Meteorologist

With how far north Alaska resides and the active weather pattern the region commonly experiences, a "typical summer" is not often seen in Alaska as would be in many places across the Contiguous US. Whereas some would think weather in the region improves by May & June, in Alaska it is not until July that the weather trends consistently more favorable, especially in regards to temperature. Winters in Alaska experience far less daylight, if any at all, which further amplifies how cold it becomes as well as delays the warming of temperatures through the spring months.

The day-to-day weather across the Alaskan Fjords and N'rn Gulf of Alaska typically experiences far less volatility during July & August compared to other months out of the year. An active gale track at other times in the year becomes near non-existent during July, and remains scarce at the most through August. Also seen with time is a S'rn migration of high pressure ridging in the Gulf of Alaska, which recedes S'ward through the summer.

While there are plenty of positives to be found with weather across the region in July & August, there is however an increased risk of fog and reduced visibilities, especially for inside routing within the fjords. The warmer moist air that the region benefits from this time of year interacts with cooler Sea Surface Temperatures (SSTs) from both the naturally colder waters of the region and the summertime glacial melt between the fjords. This generates periods of localized Advection Fog, which persists for longer than normal if trapped within valleys featuring reduced winds and less circulating air. Aside from reduced visibilities in the region, the next most-common weather alert tends to be Small Craft Advisories out in the open waters of the Northern Gulf of Alaska.

Even with the region experiencing its usual summer lull, reduced visibilities and locally enhanced conditions for smaller craft are still very important to monitor for. WRI's Heavy Weather Alerts, issued straight from the NWS/NOAA, are a great tool to monitor for any Fog or Small Craft Advisories. These can be acquired if you are presently receiving our customized forecasting services (and the 2 weeks afterwards), or by purchasing a subscription to Seaweather.net, our supplementary onboard forecast software. SeaWeather is a great tool to use around the world in any region, and a Premium Plus subscription has all the features you may require!