After weakening to a tropical storm earlier on Wednesday Hurricane Otto intensified as it approached the border between Nicaragua and Costa Rica.  At 10:00 p.m. EST on Wednesday the center of Hurricane Otto was located at latitude 11.2°N and longitude 82.2°W which put it about 120 miles east-southeast of Bluefields, Nicaragua.  Otto was moving toward the west at 9 m.p.h. (15 km/h).  The maximum sustained wind speed was 85 m.p.h. (140 km/h) and there were wind gusts to 100 m.p.h. (160 km/h).  The minimum surface pressure was 981 mb.

A Hurricane Warning is in effect for the portion of the coast from Limon, Costa Rica to Bluefields, Nicaragua.  Hurricane Watches have been issued for the portions of the coast from Bluefields to Sandy Bay Sirpi, Nicaragua and from the Panama/Costa Rica border to Limon, Costa Rica.  Tropical Storm Warnings are in effect for the  portions of the coast from Bluefields to Sandy Bay Sirpi, Nicaragua, from Puntarenas, Costa Rica to Puerto Sandino, Nicaragua and for San Andres Island.

Hurricane Otto had meandered over the same water long enough to mix cooler water to the surface.  The cooler water reduced the energy transfer to the atmosphere and the inner core of Otto weakened.  The eye disappeared and Otto weakened below hurricane intensity.  When Otto began to move west, the core of the circulation moved away from the cooler water.  Thunderstorms developed rapidly near the center of circulation and the inner core began to redevelop.  A reconnaissance plane found that the wind speed had increased above hurricane intensity again.

Hurricane Otto has a very small circulation.  Winds to hurricane force only extend out about 12 miles (19 km) from the center of circulation.  Winds to tropical storm force extend out about 70 miles (110 km) from the center.  The Hurricane Intensity Index (HII) is 12.7.  The Hurricane Size Index (HSI) is 4.7 and the Hurricane Wind Intensity Size Index (HWISI) is 17.4.  These indices indicated that Hurricane Otto is capable of causing localized minor wind damage.

The small circulation of Hurricane Otto is more symmetrical.   There are indications that a circular eye and eyewall could be reforming at the center of the hurricane.  Several bands of thunderstorms are rotating around the core of Otto.  Thunderstorms at the core were generating upper level divergence which pumped out mass and allowed the surface pressure to decrease on Wednesday evening.

Hurricane Otto will be moving through an environment that is favorable for intensification until it makes landfall.  Otto will be moving over water where the Sea Surface Temperature is near 29°C.  An upper level ridge east of the hurricane is producing southeasterly winds which are flowing near the top of the circulation.  However, those winds are weaker than they were yesterday and the vertical wind shear is less.  Hurricane Otto could strengthen further during the next few hours.

A ridge to the north of Otto is steering the hurricane toward the west and that general motion is expected to continue for another day or two.  On its anticipated track Hurricane Otto will make a landfall on the coast between the Nicaragua/Costa Rica border and Monkey Point, Nicaragua.  Winds blowing toward the coast will produce a storm surge along the southern coast of Nicaragua.  Otto could drop heavy rain over Nicaragua and Costa Rica.  Outer bands may also produce locally heavy rain over parts of Honduras and El Salvador.  The rain may be heavy enough to cause flooding and mudslides.