093  
WTNT41 KNHC 250254  
TCDAT1  
 
TROPICAL STORM OTTO DISCUSSION NUMBER 17  
NWS NATIONAL HURRICANE CENTER MIAMI FL AL162016  
900 PM CST THU NOV 24 2016  
 
RADAR DATA FROM LAS NUBES, NICARAGUA, INDICATE THAT THE CORE OF OTTO  
HAS REMAINED WELL ORGANIZED SINCE LANDFALL, WITH AN EYE STILL  
DISCERNIBLE. ON THE OTHER HAND, THE CONVECTIVE CLOUDS ASSOCIATED  
WITH THE CYCLONE HAVE WARMED CONSIDERABLY SINCE LANDFALL. THERE  
HAVE BEEN NO SURFACE OBSERVATIONS FROM THE CORE, SO THE INITIAL  
INTENSITY IS REDUCED TO A SOMEWHAT UNCERTAIN 60 KT BASED ON THE  
DECAY IN THE SATELLITE APPEARANCE.  
 
THE INITIAL MOTION ESTIMATE IS 265/11. OTTO IS LOCATED OVER  
NORTHWESTERN COSTA RICA AND SHOULD EMERGE INTO THE PACIFIC DURING  
THE NEXT FEW HOURS. EASTERLY STEERING FLOW ON THE SOUTH SIDE OF A  
DEEP-LAYER RIDGE LOCATED OVER THE NORTHWESTERN CARIBBEAN SEA AND  
SOUTHERN MEXICO IS EXPECTED TO KEEP OTTO MOVING IN A WESTWARD TO  
WEST-SOUTHWESTWARD DIRECTION FOR THE NEXT 72 HOURS OR SO. AFTER  
THAT TIME, THE CYCLONE OR ITS REMNANTS ARE EXPECTED TO REACH THE  
END OF THE RIDGE AND TURN NORTHWESTWARD. THE NEW FORECAST TRACK IS  
SIMILAR TO THE PREVIOUS TRACK THROUGH 72 HOURS, THEN IS SHIFTED A  
LITTLE TO THE LEFT OF THE TRACK BASED ON A SHIFT IN THE CONSENSUS  
MODELS.  
 
DURING THE FIRST 36 HOURS OVER THE PACIFIC, OTTO IS LIKELY TO BE  
OVER WARM SEA SURFACE TEMPERATURES IN AN ENVIRONMENT OF MODERATE TO  
STRONG EASTERLY VERTICAL WIND SHEAR. THE INTENSITY FORECAST DURING  
THIS TIME WILL SHOW A SLOW WEAKENING IN AGREEMENT WITH THE PREVIOUS  
FORECAST DUE TO THE UNCERTAINTIES IN THE STRENGTH OF THE SHEAR.  
HOWEVER, GIVEN THE LEVEL OF ORGANIZATION IT WOULD NOT BE SURPRISING  
IF SOME INTENSIFICATION OCCURRED. AROUND 48 HOURS, THE CYCLONE IS  
LIKELY TO ENCOUNTER COOLER SEA SURFACE TEMPERATURES WHICH SHOULD  
CAUSE A FASTER WEAKENING. FROM 72-120 HOURS, OTTO IS EXPECTED TO  
MOVE OVER WARMER WATER WITH DECREASING SHEAR AT THE SAME TIME IT  
ENCOUNTERS A MUCH DRIER AIR MASS. THE INTENSITY FORECAST USES THE  
PREMISE THAT THE DRY AIR WILL CAUSE THE SYSTEM TO DECAY AND THUS  
CALLS FOR OTTO TO BE A REMNANT LOW BY 120 HOURS. IT SHOULD BE  
NOTED, THOUGH, THE THE INTENSITY FORECAST AFTER 48 HOURS REMAINS  
NEAR THE LOWER EDGE OF THE GUIDANCE.  
 
THE PRIMARY THREAT FROM OTTO WILL CONTINUE TO BE TORRENTIAL  
RAINFALL, WHICH WILL RESULT IN DANGEROUS FLOODING AND MUDSLIDES.  
 
SINCE OTTO HAS MAINTAINED ITSELF AS A TROPICAL CYCLONE ALL THE WAY  
ACROSS THE LAND MASS OF CENTRAL AMERICA, BASED ON NATIONAL WEATHER  
SERVICE AND WORLD METEOROLOGICAL ORGANIZATION PROTOCOLS, IT WILL  
RETAIN THE NAME OTTO WHEN IT MOVES OVER THE EASTERN PACIFIC IN A FEW  
HOURS. PRODUCT HEADERS WILL CHANGE TO EASTERN PACIFIC HEADERS  
BEGINNING WITH THE NEXT COMPLETE ADVISORY AT 0900 UTC. THE  
INTERMEDIATE ADVISORY AT 0600 UTC WILL BE ISSUED UNDER AN ATLANTIC  
HEADER. THE ATCF IDENTIFIER WILL CHANGE FROM AL162016 TO EP222016  
AT 0900 UTC.  
 
FORECAST POSITIONS AND MAX WINDS  
 
INIT 25/0300Z 10.9N 85.6W 60 KT 70 MPH...INLAND  
12H 25/1200Z 10.5N 87.4W 55 KT 65 MPH...OVER THE PACIFIC  
24H 26/0000Z 10.0N 90.0W 55 KT 65 MPH  
36H 26/1200Z 9.6N 93.0W 50 KT 60 MPH  
48H 27/0000Z 9.4N 96.0W 45 KT 50 MPH  
72H 28/0000Z 9.5N 102.0W 45 KT 50 MPH  
96H 29/0000Z 11.0N 105.0W 40 KT 45 MPH  
120H 30/0000Z 13.0N 106.0W 30 KT 35 MPH...POST-TROP/REMNT LOW  
 

 
FORECASTER BEVEN  
 
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