Tropical Disturbance in the Federated States of Micronesia
The Joint Typhoon Warning Center has issued a Tropical Cyclone Formation Advisory (TCFA) for disturbed weather located southwest of Chuuk in the tropical Pacific. MIMIC Total Precipitable Water fields, above, show the development of a circulation near 150oE Longitude and 5oN Latitude between 0000 UTC 17 May and 0000 UTC 19 May. At present the system is very close to the Equator, and the low latitudes may somewhat inhibit its development in the short term. The circulation of the system is also apparent in Advanced Scatterometry (ASCAT) data from MetopB, shown below and available here. The HY-2C satellite returned scatterometry data over the circulation center, also shown below (taken from this site).
What does the future hold for this system? Dynamic Layer Mean Winds, below, (from the SSEC Tropical Weather website), suggest that in the short term the system might be moving to the northeast (consistent with the track from JTWC here).
The invest is moving over very warm waters, and is in a narrow region of modest shear, as shown in the toggle below.
Himawari9 Clean Window infrared imagery, below, from 00 – 17 UTC on 19 May, shows vigorous convective development just west of 150oE and south of 10oN (perhaps some of this intensification in the organization is part of the well-known diurnal cycle in tropical cyclone convection as discussed here, for example). Note also the northward and eastward motion to the north of the convection. There appears to be good ventilation away from the storm (strong upper-level divergence is diagnosed, per this 1500 UTC analysis from the SSEC Tropical Weather website).
The ventilating flow from the storm center is perhaps more apparent in the upper-level water vapor imagery, shown below.
You can find more information on this system at following websites: JTWC. NWS Guam (they recently had a map discussion on Facebook live); SSEC Tropical Website; Tokyo RSMC. The next name for western Pacific tropical systems is Mawar, the Malaysian word for ‘Rose’. Residents of the Guam and other Marianas Islands should pay particular attention to this storm as current forecasts have it moving through that island chain next week.