Super Typhoon Guchol (Butchoy) Update #12

Guchol (Bagyong Butchoy) rapidly intensified overnight and is now a Super Typhoon with maximum sustained winds of 240kph and gusts of up to 295kph. It was last located approximately 650km east northeast of Casiguran, Aurora. STY Guchol is currently moving north northwestward at 25kph.

IR Image from NRLMRY

The latest satellite image continues to show a well-defined eye surrounded by a ring of strong convective activity. Poleward outflow is also improving while equatorward outflow continues to be excellent. However, we have noticed some warming in the cloud tops and disruptions particularly on the northwestern side. A recent microwave image also hints at concentric bands surrounding the core which could suggest that an eyewall replacement cycle (EWRC) is getting started.

EWRCs are sometimes unpredictable and their effects on cyclones vary as well. A cycle will definitely disrupt Guchol's intensification trend and depending on how fast it finishes, the storm might not even be able to recover. Nevertheless, we still think Guchol will maintain its strong intensity throughout the cycle (although it could weaken to Category 3 along the way). Forecasts remain the same for Okinawa and the rest of the Japanese Islands. Worst conditions are still forecast to occur from Monday afternoon to Tuesday morning.

We'll have another update later this afternoon.
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Issued (22 UTC) 6am PhT 061812