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TROPICAL STORM OTTO DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL162016
400 AM EST TUE NOV 22 2016

Deep convection has continued to burst near the low-level center of
Otto tonight.  A pair of ASCAT passes between 02Z and 03Z showed
peak winds of around 45 kt, which support maintaining the intensity
at 50 kt for this advisory.  This intensity estimate is also
represents a blend of the 06Z subjective Dvorak estimates of 45 kt
and the latest UW-CIMSS ADT estimate of 53 kt.  An Air Force Reserve
Hurricane Hunter aircraft is scheduled to investigate Otto later
this morning.

Otto's outflow pattern remains restricted south and southeast of the
center, consistent with about 20 kt of shear analyzed over the
cyclone by the SHIPS model analysis and UW-CIMSS.  This shear is
forecast to persist for the next 24 h or so and then abate somewhat
by 36 hours.  Given this, some gradual strengthening is expected
while Otto moves over waters of around 29C, and the NHC forecast
shows Otto becoming a hurricane in 24 to 36 h.  The official
forecast through 48 h is a little above the intensity consensus and
close to the latest FSU Superensemble and the NOAA HFIP consensus
aid HCCA.  After that time, land interaction should result in
weakening and much of the guidance continues to suggest that Otto
will weaken to a remnant low after it emerges into the eastern
Pacific, and this is still reflected in the official forecast.  It
is worth noting, however, that the ECMWF maintains Otto as a
stronger cyclone over the Pacific through day 5.

After drifting south-southeastward overnight, Otto is estimated to
be stationary.  Little net motion is expected today while the
tropical cyclone is caught in a region of weak steering currents. By
24 hours, a mid-level ridge will begin to build north of Otto, which
should impart a west-northwestward motion and then a westward turn
at a slightly faster forward speed by 48 h as the ridge amplifies.
This synoptic pattern should steer Otto toward the coast of Central
America in 48 to 72 hours.  After that time, a further westward
acceleration is expected as the mid-level ridge builds westward.
The new NHC track forecast is faster than the previous one at 48
hours and beyond and has been adjusted southward at days 3-5.  The
new official forecast lies between HCCA and the FSU Superensemble
through 48 hours and is close to a blend of the GFS and ECMWF after
that time.

FORECAST POSITIONS AND MAX WINDS

INIT  22/0900Z 10.7N  79.0W   50 KT  60 MPH
 12H  22/1800Z 10.7N  79.1W   55 KT  65 MPH
 24H  23/0600Z 10.9N  79.8W   60 KT  70 MPH
 36H  23/1800Z 11.2N  80.8W   65 KT  75 MPH
 48H  24/0600Z 11.2N  82.0W   70 KT  80 MPH
 72H  25/0600Z 11.0N  85.2W   50 KT  60 MPH...INLAND
 96H  26/0600Z 10.5N  89.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  27/0600Z 10.0N  93.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Brennan

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