Earlier today, JMA (along with PAGASA and JTWC) upgraded the tropical depression in the Philippine Sea into the 15th tropical storm of the 2014 WPAC Season: Tropical Storm Kalmaegi. (Listen to pronunciation here) It also gained the Philippine name Luis.
As of 0900 UTC, the center of Tropical Storm Kalmaegi was located approximately 710 km east of Virac, Philippines or 1060 km east of Metro Manila. Kalmaegi is moving west at 22 km/h with sustained winds near the center at 65 km/h gusting up to 95 km/h. The central pressure has dropped to 998 hPa.
The main reason behind the upgrade was better satellite presentation, confirmed by Dvorak analyses. Both JTWC and NESDIS noted convection wrapping 60-70% around the center of circulation, which yields a T3.0.
The short-term forecast still has some work to do. The frontal boundary southeast of Japan has re-established the Baiu boundary–a stationary front that separates the tropical airmass from the mid-latitude airmass. Because this feature is stationary, it’s influence of the track of Kalmaegi will be limited, but will couple with general low pressure across the South China Sea to influence Kalmaegi west-northwestward toward Luzon. A majority of the models were pin-pointing a landfall in Isabela province Sunday or Monday (the basis of JMA’s and PAGASA’s forecast), but a southward shift has been noticed today with some models going as far south as Metro Manila. As a result, JTWC has shifted their track southward toward Aurora province. Either way, those throughout Luzon should continue to monitor the progress of this storm. Additionally, as Kalmaegi approaches, it will enhance the Southwest Monsoon. As a result, increased showers and thunderstorms are expected this weekend and early next week for the Visayas and Mindanao.
The intensity forecast, like most intensity forecasts, is hard to nail down. GFS and the GFDN are throttled back, intensifying Kalmaegi to around 120 km/h prior to landfall. On the other hand, HWRF is the most bullish, ramping the storm up to 215 km/h prior to landfall. JTWC has been pretty consistently saying at or about 155 km/h. Interestingly, JMA has continued to be conservative, only strengthening Kalmaegi to a 100 km/h severe tropical storm. Plenty of challenges remain, so we’ll continue to monitor.
Shifting gears toward impacts, right now the big story will really be rainfall. Flash flooding and possible landslides in Luzon will be possible as rain totals climb up to 200-300 mm Sunday and Monday, with lower amount across the Visayas and Mindanao thanks to the Southwest Monsoon. The severe winds will be confined near landfall (whether that’s Isabela, Aurora, or elsewhere). Storm surge will be a factor for those in low-lying areas along the immediate coastlines. As a result to the forecast threat, PAGASA has issued Public Storm Warning Signal #1 for Catanduanes, identifying the region of possible 30-60 km/h winds in at least 36 hours.
Keep posted as we continue to monitor the progress of this storm.