Tropical Storm Nicole Prompts Hurricane Watch for Bermuda

While water rescues continued in parts of North Carolina and recovery efforts accelerated after the passage of Hurricane Matthew, Tropical Storm Nicole prompted the issuance of a Hurricane Watch for Bermuda.  At 5:00 p.m. EDT on Monday the center of Tropical Storm Nicole was located at latitude 26.3°N and longitude 65.4°W which put it about 415 miles (670 km) south of Bermuda.  Nicole was moving toward the north at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 992 mb.

After becoming a hurricane last Thursday Nicole weakened back to a tropical storm during the weekend.  A combination of intermittent vertical wind shear and drier air caused the structure of Tropical Storm Nicole to deteriorate.  The eye disappeared and the thunderstorms in the rainbands weakened.  There appears to be a remnant of the eyewall, but it only consists of lower clouds and showers.  Several rainbands exist around the circulation, although they are not as strong as they were a few days ago.  Thunderstorms southeast of the center of circulation seem to have increased on Monday afternoon.  The new thunderstorms are generating some upper level divergence but it is not currently well developed.

Tropical Storm Nicole is an environment that is marginal for intensification.  An upper level trough north of Nicole is generating some vertical wind shear.  In addition cooler, drier air has moved close to the western part of the circulation of Tropical Storm Nicole.  On the other hand, Tropical Storm Nicole is moving over water where the Sea Surface Temperature is near 29°C.  So, there is plenty of energy in the upper ocean.  The vertical wind shear and drier air could prevent Tropical Storm Nicole from intensifying much on Tuesday.  The upper level trough will move off to the east and the vertical wind shear could decrease during the middle of the week.  If the shear diminishes and not much drier air gets pulled into the circulation, then Tropical Storm Nicole has a chance to intensify into a hurricane.

A high pressure system blocked the northward movement of Tropical Storm Nicole and the high even pushed Nicole toward the south at times during the weekend.  The high appears to be moving farther to the east, which is allowing Tropical Storm Nicole to move slowly toward the north.  As the high pressure system shifts to the east, it will start to steer Tropical Storm Nicole more toward the northwest.  When Nicole reaches the western end of the high, it will turn toward the northeast.  The westerly winds in the middle latitudes will accelerate Nicole toward the northeast later this week.  On its anticipated track the center of Tropical Storm Nicole could pass near Bermuda on Thursday.