WTPZ42 KNHC 260238 RRA

TCDEP2



TROPICAL STORM OTTO DISCUSSION NUMBER  21

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP222016

900 PM CST FRI NOV 25 2016



OTTO IS SHOWING THE EFFECTS OF 20-25 KT OF EASTERLY VERTICAL WIND

SHEAR, AS THE CENTER IS LOCATED NEAR THE EASTERN EDGE OF THE MAIN

CONVECTIVE AREA.  SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB

REMAIN 55 KT, AND THERE IS A RECENT ESTIMATE OF 47 KT FROM THE

CIMSS SATELLITE CONSENSUS TECHNIQUE.  BASED ON THESE DATA, THE

INITIAL INTENSITY REMAINS 50 KT.



THERE ARE A LOT OF NEGATIVE ENVIRONMENTAL FACTORS IN THE INTENSITY

FORECAST.  IN THE FIRST 12-24 HOURS, THESE INCLUDE MODERATE TO

STRONG SHEAR AND ABUNDANT DRY AIR SEEN IN WATER VAPOR IMAGERY NEAR

OTTO.  AT 24-36 HOURS, THE CYCLONE IS LIKELY TO MOVE ACROSS AN AREA

OF COOLER SEA SURFACE TEMPERATURES.  FINALLY, FROM 72-120 HOURS OTTO

OR ITS REMNANTS SHOULD ENCOUNTER MORE DRY AIR AND UPPER-LEVEL

CONVERGENT FLOW.  GIVEN THESE FACTORS, IT IS NOT A SURPRISE THAT THE

GLOBAL MODELS FORECAST OTTO TO MEET A QUICK DEMISE.  ON THE OTHER

HAND, THE SHIPS AND LGEM MODELS FORECAST A SLOWER DECAY AND SUGGEST

OTTO COULD STILL BE A TROPICAL CYCLONE AT 120 HOURS.  THE NEW

INTENSITY FORECAST WILL LEAN A LITTLE MORE TOWARD THE GLOBAL MODELS

AND SHOW LOWER INTENSITIES THAN THE PREVIOUS FORECAST, WITH THE

CYCLONE FORECAST TO WEAKEN TO A DEPRESSION AT 96 HOURS AND TO A

REMNANT LOW AT 120 HOURS.  HOWEVER, IF THE GLOBAL MODELS ARE RIGHT

BOTH OF THESE EVENTS COULD OCCUR EARLIER.



THE INITIAL MOTION IS 255/14.  THE CYCLONE CONTINUES TO BE SOUTH OF

A STRONG DEEP-LAYER RIDGE OVER MEXICO, AND THIS STEERING PATTERN

WILL FORCE OTTO TO MOVE ON A GENERAL WEST-SOUTHWESTWARD TO WESTWARD=