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Hurricane Marie Discussion Number   8
NWS National Hurricane Center Miami FL       EP182020
800 PM PDT Wed Sep 30 2020
 
Passive microwave satellite data and satellite intensity estimates 
indicate that Marie has undergone a brief intensity hiatus since the 
previous advisory.  Date from the 2055Z AMSR and 2306Z SSMI 
microwave passes indicated that the earlier eye feature has eroded 
some and opened up on the east side due to dry air entrainment and 
modest easterly vertical wind shear of about 10 kt. The initial 
intensity is being held at 65 kt based on subjective Dvorak 
classifications of T4.0/65 kt from both TAFB and SAB, and UW-CIMSS 
objective intensity estimates of T4.1/67 kt and 62 kt from ADT and 
SATCON, respectively.

The motion estimate is 280/14 kt.  The latest NHC model guidance 
remains in excellent agreement through about 96 h on Marie moving 
west-northwestward toward a weakness in the subtropical ridge 
located to the north of the cyclone. Thereafter, there is 
considerable divergence in the guidance with the ECMWF and UKMET 
taking Marie more westward, while the GFS, HWRF, and HMON models 
take the hurricane northward into a break in the ridge; the latter 
scenario is preferred by the various simple and corrected consensus 
models.  As a result, no significant changes were required to the 
previous forecast, and the new forecast track essentially lies down 
the model of the tightly packed consensus model envelope.

Although the eyewall has eroded somewhat, the small inner-core wind 
field still appears to be intact based on low-level cloud features 
seen in 36-37 GHz satellite imagery.  Once the narrow dry air 
intrusions mix out in about 6 hours or so, rapid intensification 
(RI) should resume and continue through 48 hours while the shear 
gradually decreases to near zero by then. By 60 hours and continuing 
through the remainder of the forecast period, cooler sea-surface 
temperatures, along with cold upwelling generated by Marie, should 
cause the hurricane to weaken, with rapid weakening likely beginning 
by 72 hours when significant southwesterly vertical wind shear kicks 
in ahead of a deep-layer trough that will be moving eastward out of 
the central Pacific. The new official intensity forecast is 
essentially identical to the previous NHC forecast, and lies along 
the extreme upper end of the intensity guidance, about midway 
between the Navy COAMPS-TC model (CTCI) and the NOAA-HCCA 
corrected-consensus model.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/0300Z 14.5N 116.5W   65 KT  75 MPH
 12H  01/1200Z 14.7N 118.6W   80 KT  90 MPH
 24H  02/0000Z 15.3N 121.3W  100 KT 115 MPH
 36H  02/1200Z 16.2N 123.6W  115 KT 130 MPH
 48H  03/0000Z 17.2N 125.6W  120 KT 140 MPH
 60H  03/1200Z 18.2N 127.5W  100 KT 115 MPH
 72H  04/0000Z 19.1N 129.1W   85 KT 100 MPH
 96H  05/0000Z 20.7N 131.8W   65 KT  75 MPH
120H  06/0000Z 22.6N 134.3W   45 KT  50 MPH
 
$$
Forecaster Stewart
 
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