Bonnie
Tropical Depression 2 was upgraded to Tropical Storm Bonnie at 2100 UTC on Saturday 28 May, the second named storm of the 2016 Atlantic Season (Hurricane Alex, which formed in January, was the first named storm). The water vapor animation above shows that Bonnie’s initial spin may be traced to a front associated with an occluded system which crawled through the eastern United States, exiting on about 23 May 2016. It’s not uncommon for vorticity associated with extratropical cyclone fronts to sow the seed of a tropical cyclone, especially early (or late) in the season. In this case, the cold front failed to pass Bermuda, and by 27 May, persistent thunderstorms about halfway between Bermuda and the Bahamas suggested tropical cyclogenesis was underway (GOES-13 visible image animations: 26 May | 27 May).![MIMIC Total Precipitable Water derived from Microwave imagery, 1800 UTC 28 May - 1700 UTC 30 May [click to enlarge]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/sites/5/2016/05/MIMIC_TPW_Bonnie_72hrs_ending1700UTC_30May.gif)
MIMIC Total Precipitable Water derived from Microwave imagery, 1800 UTC 28 May – 1700 UTC 30 May [click to enlarge]
![Suomi NPP VIIRS Day/Night Band (0.70 µm Visible) and Infrared (11.45 µm) Imagery at 0621 UTC on 27 May 2016 [click to enlarge]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/sites/5/2016/05/DNB_NPP_11.45_27May2016_0621toggle.gif)
Suomi NPP VIIRS Day/Night Band (0.70 µm Visible) and Infrared (11.45 µm) Imagery at 0621 UTC on 27 May 2016 [click to enlarge]
![Suomi NPP VIIRS Day/Night Band (0.70 µm Visible) and Infrared (11.45 µm) Imagery at 0742 UTC on 28 May 2016 [click to enlarge]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/sites/5/2016/05/DNB_NPP_11.45_28May2016_0742toggle.gif)
Suomi NPP VIIRS Day/Night Band (0.70 µm Visible) and Infrared (11.45 µm) Imagery at 0742 UTC on 28 May 2016 [click to enlarge]
![Suomi NPP VIIRS Day/Night Band (0.70 µm Visible) and Infrared (11.45 µm) Imagery at 0723 UTC on 29 May 2016 [click to enlarge]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/sites/5/2016/05/DNB_NPP_11.45_29May2016_0723toggle.gif)
Suomi NPP VIIRS Day/Night Band (0.70 µm Visible) and Infrared (11.45 µm) Imagery at 0723 UTC on 29 May 2016 [click to enlarge]
![GOES-13 Infrared (10.7 µm) Imagery at 2045 UTC on 28 May and at 1045 UTC 29 May 2016; the Yellow Arrow points to the low-level circulation center [click to enlarge]](https://cimss.ssec.wisc.edu/satellite-blog/wp-content/uploads/sites/5/2016/05/GOES13_IR4_28MAY2016_2045_29MAY_1045toggle.gif)
GOES-13 Infrared (10.7 µm) Imagery at 2045 UTC on 28 May and at 1045 UTC 29 May 2016; the Yellow Arrow points to the low-level circulation center [click to enlarge]
===== 01 June Update =====
The remnant circulation of Bonnie moved very slowly northeastward during the 30 May – 01 June period, as seen in GOES-13 Visible (0.63 µm) images covering each of those 3 days (above; also available as a large 95 Mbyte animated GIF). The periodic formation of deep convective clusters continued to produce heavy rainfall over parts of far eastern North and South Carolina.On the morning of 01 June, an overpass of the Metop-B ASCAT instrument sampled the flow around the low-level circulation center (LLCC) off the coast of North Carolina; several hours later, Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images provided a high-resolution view of the system at 1755 UTC (below). Cloud-top IR brightness temperatures were as cold as -78º C within the small convective cluster located just north of the LLCC.