Throughout the day Friday, we’ve seen fluctuations in the satellite appears for Typhoon Phanfone. Recent trends this afternoon show a clearing eye as deep convection begins to wrap solid around the storm. The bulk of the convection is found on the south side of the eye, with a weaker eyewall along the north.
The near-term forecast challenge is the major turn that is expected this weekend. Throughout the day Friday, much of Japan saw a weak frontal boundary pass through, bringing increased cloudiness and periods of rain. This feature–while bringing cooler temperatures for Japan–is responsible for the sharp turn to the east for Typhoon Phanfone. Timing and angle of the front picking Phanfone up and pushing it eastward will be significant for the track forecast. Out of the major agencies warning on Phanfone, Japan Meteorological Agency provides the westernmost track. Philippines’ PAGASA has a significantly eastern track, followed by the United States’ JTWC.
Here are the take-aways for the near-term forecast: Minamidaitojima is under threat for tropical storm-force winds throughout much of the day on Saturday. Interests in Okinawa appear like they will avoid the worse of the storm thanks to the aforementioned front. However, be mindful for gusty winds (up to 90 km/h) and increased seas on the eastern shore.
At this point, we look at the longer-term track forecast. I cannot stress the importance to the near-term turn and its implications to any potential landfall in or around the Kanto Plain. Of note, because of the eastern track from JTWC (i.e. an earlier turn to the east), the center of Phanfone avoids land with the strongest winds remaining over water. If this track verifies, typhoon-force winds will remain off-shore with possible tropical storm-force winds affecting the Tokyo area. JMA brings the eye over Shizuoka prefecture with the other agencies ranging between Aichi and Chiba. Obviously any minor shifts in the track, especially with regards to the turn east, will result in huge changes to the landfall point and it’s impact to those living in the Kanto Plain.
As of 0900 UTC Friday, the maximum winds with Typhoon Phanfone were 175 km/h with gusts up to 250 km/h. Some additional strengthening is possible this weekend as the front begins to interact with the frontal boundary. Thereafter, rapid weakening and acceleration should occur Sunday evening into Monday as the storm nears Japan.
As for storm impacts… winds will pick up in the northern Ryukyus and Kyushu on Saturday evening. We’ll see these winds spread across coastal Honshu throughout Sunday and into the Kanto region by Monday morning. Beyond the winds, heavy rains will follow over much of southern Japan with localized flooding and possible landslides. Models suggest that rainfall totals throughout the region should range between 100-150 mm, with isolated amounts up to 250 mm through Monday evening.
We’ll continue to monitor the situation and keep you posted. Stay safe.