Tag Archives: Nicaragua

Invest 90L Meandering Over Southwest Caribbean Sea

An area of low pressure designated as Invest 90L has meandered over the southwestern Caribbean Sea during the past several days.  At 7:00 p.m. EST on Thursday the center of Invest 90L was located at latitude 12.3°N and longitude 81.3°W which put it about 170 miles (275 km) east of Bluefields, Nicaragua.  Invest 90L was moving toward the west at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 25 m.p.h. (40 km/h) and there were wind gusts to 35 m.p.h. (55 km/h).  The minimum surface pressure was 1006 mb.

Invest 90L consists of a broad area of low pressure over the southwestern Caribbean Sea.  There is a definite area of counterclockwise rotation, but the is no well defined core at the center of the low.  There is a swirl of low clouds and showers at the center of Invest 90L, but there are no thunderstorms near the center.  Thunderstorms form and dissipate in bands around the periphery of the circulation.

The environment around the southwestern Caribbean Sea is not as favorable for the development of a tropical cyclone as it was earlier this week.  Invest 90L is moving over water where the Sea Surface Temperature is near 29°C.  However, northerly winds blowing across the Gulf of Mexico have transported drier air over the northwestern Caribbean Sea.  The drier air has not reached Invest 90L, but the drier air is just to the northwest of the low pressure system.  An upper level trough over the Gulf of Mexico is producing southwesterly winds which are blowing over the top of Invest 90L.  Those winds are generating moderate vertical wind shear which is inhibiting the organization of the low pressure system.  Even with the inhibiting factors the National Hurricane Center is indicating that the probability of the formation of a tropical cyclone during the next five days is 70%.

The fact that there is only a low level circulation means that Invest 90L is being steering by winds closer to the surface.  The winds in the lower levels have been pushing the low pressure system very slowly toward the west.  Guidance from numerical models suggests that Invest 90L could meander over the southwestern Caribbean Sea for several more days.

Possible Tropical Development Over the Southwest Caribbean Sea

A weak trough of low pressure over the Southwestern Caribbean Sea has the potential to develop into a tropical cyclone during the next few days.  The National Hurricane Center is stating that there is a 70% probability of the formation of a tropical cyclone during the next five days.  A broad trough of low pressure stretches from near Panama to east of Nicaragua.  There is not a well defined center of low pressure within the broader trough.  There were more thunderstorms earlier today, but many of them weakened on Monday evening.  A few more thunderstorms developed north of Panama during the past several hours.

The environment over the southwestern Caribbean Sea is favorable for intensification.  The Sea Surface Temperature of water in that part of the Caribbean Sea is around 29°C.  There is an upper level ridge over the area.  The winds are weaker in the center of the ridge and there is little vertical wind shear in that part of the atmosphere.  The ridge providing a source of upper level divergence which is allowing the surface pressure to decrease slowly.

Several numerical models are suggesting that a tropical cyclone could develop during the next few days.  The models do differ on exactly when and where the tropical cyclone could form.  The probability of development will be higher if the area of lower pressure remains over the water.  However, if the trough of low pressure drifts closer to the coast of Nicaragua, then the interaction of the circulation with land could inhibit the formation of a tropical cyclone.  Even if a tropical cyclone does not form, the trough could produce locally heavy rain over parts of Panama, Nicaragua and Honduras.