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Tropical Storm Ema Discussion Number   5
NWS Central Pacific Hurricane Center Honolulu HI   CP012019
500 AM HST Sun Oct 13 2019
 
There was a brief burst of deep convection that covered most of the 
low-level circulation center (LLCC) of Ema for a few hours earlier
tonight. The LLCC is now completely exposed, but a few thunderstorms
are still developing more than 45 n mi north of the LLCC. An earlier
scatterometer pass from 0727Z confirmed that there were still 35 kt
winds in the northeast quadrant of Ema. The latest subjective Dvorak
intensity estimates from SAB and HFO indicate the intensity is near
35 kt. Therefore, we will maintain the initial intensity for this
advisory at 35 kt.
 
With the tropical cyclone remaining shallow, the primary steering
mechanism is a surface high centered far to the northeast of the
main Hawaiian Islands. The initial motion estimate for this advisory
is 300/9 kt. Most of the reliable guidance remains in close
agreement on the near-term track forecast. This guidance shows Ema
will likely start to move toward the northwest at a slightly faster
forward speed during the next 12 hours. This northwest motion is
forecast to persist through the next 24 to 36 hours. Ema remains
north of a mid- to upper-level ridge axis, which keeps strong
southwesterly vertical wind shear over the LLCC. As a result, the
latest forecast continues to show a steady spin-down of the tropical
cyclone during the next 12 to 24 hours. The intensity forecast
indicates Ema may weaken to a tropical depression during the next
12 to 24 hours. After that, it is forecast to weaken to a
post-tropical remnant low within 36 hours, followed by dissipation.
 
Note that Ema poses no direct threat to the main Hawaiian Islands.
However, since there is still uncertainty in the rate of weakening
and the eventual path of Ema, a Tropical Storm Watch remains posted
for portions of the Papahanaumokuakea Marine National Monument. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/1500Z 22.2N 166.2W   35 KT  40 MPH
 12H  14/0000Z 23.7N 167.7W   30 KT  35 MPH
 24H  14/1200Z 26.1N 168.4W   30 KT  35 MPH
 36H  15/0000Z 28.4N 168.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  15/1200Z...DISSIPATED
 
$$
Forecaster Houston
 
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