Monthly Archives: October 2017

Low Pressure Develops Over Southwest Caribbean Sea

An area of low pressure developed over the southwestern Caribbean Sea on Tuesday afternoon and the system was designated Invest 90L.  At 5:00 p.m. EDT on Tuesday the center of Invest 90L was located at latitude 12.0°N and longitude 80.7°W which put it about 200 miles (320 km) east of Bluefields, Nicaragua.  It was moving toward the west-northwest at 5 m.p.h. (8 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1008 mb.

The circulation of Invest 90L was still organizing on Tuesday afternoon.  The area of low pressure appeared to have a distinct center of circulation.  Several bands of showers and thunderstorms were forming south and east of the center of circulation.  There were fewer showers and thunderstorms northwest of the center.  There was some upper level divergence that was pumping mass away to the south and west of the center.

Invest 90L will be moving through an environment favorable for intensification.  The Sea Surface Temperature in the southwest Caribbean Sea is near 30°C and the warm water is fairly deep.  The energy content of the water in that area is high.  An upper level ridge centered over the western Gulf of Mexico is producing northeasterly which are blowing toward the northwestern side of Invest 90L.  Those winds are producing some vertical wind shear, but the shear is not likely to be strong enough to prevent the formation of a tropical cyclone.  Invest 90L is likely to become a tropical depression or storm during the next 24 to 48 hours.  If the center remains east of Nicaragua, rapid intensification could occur after the circulation consolidates around the low level center.

Invest 90L is moving slowly toward the west-northwest as it moves near the southern side of a mid-level ridge.  That ridge could steer Invest 90L close to the coast of Nicaragua during the next several days.  The mid-level ridge is forecast to move east to near the Bahamas during the next 24 to 48 hours.  After that time, southerly winds are forecast to steer Invest 90L toward the north.  On its anticipated track the center of Invest 90L could move very close to Nicaragua during the next day or two.  It could bring locally heavy rain to Nicaragua and Honduras.  Invest 90L could move into the Gulf of Mexico in a few days.  The intensity of Invest 90L when it reaches the Gulf will depend on how much it interacts with Nicaragua and the Yucatan peninsula.  If the center stays over water, then it could be a hurricane when it reaches the Gulf of Mexico.  If the center spends more time over land, then the system will be weaker when it reaches the Gulf.  Some models are forecasting that a hurricane could make landfall on the northern Gulf Coast during the weekend.