JTWC Issues Tropical Cyclone Formation Alert for System Forming Over Marianas


Guam – The Joint Typhoon Warning Center [JTWC] has issued a Tropical Cyclone Formation Alert for the system that is forming over the Marianas and will be affecting our weather in the coming days.

 READ the Formation Alert on the JTWC website HERE

 Joint Typhoon Warning Center Pearl Harbor Hawaii – Tropical Cyclone Formation Alert

1. Formation of a significant tropical cyclone is possible within 140 nm either side of a line from 14.9N 149.2E to 15.4n 144 within the next 12 to 24 hours. 

Available data does not justify issuance of numbered tropical cyclone warnings at this time. Winds in the area are estimated to be 15 to 20 knots. Metsat imagery at 090600Z indicates that a circulation center is located near 15.1N 148.5E. The system is moving westward at 06 knots.

2. Remarks: The area of convection previously located near 14.8N and 149.5E, is now located near 15.0N 149.1E, approximately 275 nm east-northeast of Andersen AFB, Guam. Animated multispectral satellite  imagery indicates a slowly consolidating system with multiple low-level circulation centers (llcc) and broad, albeit broken, convective banding located along the southern semi-circle. a 090724Z SSMIS microwave image depicts a disorganized system with broken convection wrapping along the southern semi-circle. upper level analysis indicates a generally favorable environment with low to moderate vertical wind shear (10 to 20 kts) and diffluent easterly outflow. 

Dynamic model guidance indicates continued development as the system tracks west-northwestward towards the Northern Marianas Islands. Maximum sustained surface winds are estimated at 15 to 20 knots. Minimum sea level pressure is estimated to be near 1004 mb. The potential for the development of a significant tropical cyclone within the next 24 hours is high.

3. This alert will be reissued, upgraded to warning or cancelled by 101000Z.