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Hurricane Miriam Forecast Discussion


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673 
WTPZ45 KNHC 292148 CCA
TCDEP5

Hurricane Miriam Discussion Number  15...Corrected
NWS National Hurricane Center Miami FL       EP152018
200 PM PDT Wed Aug 29 2018

Corrected WMO header in fourth paragraph

The satellite presentation of Miriam has significantly improved over
the past 12 hours or so.  Several microwave images received since
the release of the previous advisory revealed a significant
increase in organization with convection wrapping nearly
completely around the center.  Recent visible satellite images have
shown hints of an eye, but the surrounding convective tops have
warmed somewhat.  Subjective and objective Dvorak intensity
estimates all support hurricane strength, and the initial intensity
is increased to 65 kt for this advisory.

Satellite fixes show that Miriam has slowed down and is moving
westward or 270/8 kt. The hurricane is near the western edge of
the subtropical ridge and is forecast to turn west-northwestward
very soon.  A large mid- to upper-level trough located northeast of
the Hawaiian Islands should cause Miriam to turn northwestward, then
northward over the next couple of days, and the dynamical models
are in good agreement through 72 hours.  After that time, model
differences remain as the ECMWF continues to take a deeper cyclone
much faster northward than the remainder of the guidance.  The NHC
forecast continues to lean toward the solution of a weaker cyclone
turning northwestward or west-northwestward near the end of the
forecast period.  The updated NHC forecast is once again south of
the model consensus at days 4 and 5 and is in best agreement with
the GFS ensemble mean.

Miriam has about another 12-24 h over warm water and within a light
to moderate wind shear environment in which to strengthen.  After
that time, a significant increase in southwesterly shear is
anticipated and Miriam is forecast to weaken fairly quickly
between 36 and 72 hours.  Miriam should reach SSTs below 26C by
96 h and should degenerate into a remnant low by that time.

Miriam will move into the Central Pacific Basin shortly and this is
last NHC advisory on this system.  Future information on Miriam can
be found in advisories issued by the Central Pacific Hurricane
Center beginning at 5 PM HST (0300 UTC), under AWIPS header
HFOTCPCP3, WMO header WTPA33 PHFO, and on the web at
http://www.prh.noaa.gov/cphc

FORECAST POSITIONS AND MAX WINDS

INIT  29/2100Z 14.0N 139.7W   65 KT  75 MPH
 12H  30/0600Z 14.4N 140.7W   70 KT  80 MPH
 24H  30/1800Z 15.3N 141.3W   75 KT  85 MPH
 36H  31/0600Z 16.7N 141.5W   70 KT  80 MPH
 48H  31/1800Z 18.4N 141.5W   60 KT  70 MPH
 72H  01/1800Z 21.5N 142.7W   40 KT  45 MPH
 96H  02/1800Z 24.7N 145.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  03/1800Z 27.0N 149.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Brown