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Hurricane Norman Forecast Discussion


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095 
WTPZ41 KNHC 040235
TCDEP1

Hurricane Norman Discussion Number  28
NWS National Hurricane Center Miami FL       EP162018
800 PM PDT Mon Sep 03 2018

Norman continues to slowly weaken.  Satellite images indicate that
the banding features are not as well organized as they were earlier
today, and the cloud tops have warmed some during the past few
hours.  The Dvorak classifications have decreased, and a blend of
the latest estimates supports lowering the initial intensity to 80
kt.

Norman continues to move quickly westward at 18 kt steered by a
strong subtropical ridge to its north-northeast.  This general
heading, but with a significant decrease in forward speed, is
expected during the next day or two while Norman nears the edge of
the ridge.  Thereafter, a turn to the northwest and then
north-northwest is expected while Norman moves around the ridge and
toward a large deep-layer trough over the northern Pacific.  There
remains a fair amount of spread on where and when Norman makes the
turn, but the guidance did not change much overall this cycle.
Therefore, only small changes were made to the previous advisory,
and this forecast lies close to the middle of the guidance envelope.

Norman could weaken a little more overnight and on Tuesday, but the
guidance shows the intensity flattening out in the 24- to 48-hour
time period.  After that time, however, a sharp increase in shear,
cooler waters, and a drier air mass should cause more significant
weakening.  The NHC intensity forecast is largely an update of the
previous one and in line with the IVCN and HCCA consensus models.

Now that Norman has crossed into the central Pacific basin, future
advisories on this system will be issued by the Central Pacific
Hurricane Center.  These forecasts can be found on the web at
http://www.prh.noaa.gov/cphc.

FORECAST POSITIONS AND MAX WINDS

INIT  04/0300Z 19.8N 140.2W   80 KT  90 MPH
 12H  04/1200Z 20.0N 142.5W   75 KT  85 MPH
 24H  05/0000Z 20.1N 144.9W   70 KT  80 MPH
 36H  05/1200Z 20.2N 147.0W   70 KT  80 MPH
 48H  06/0000Z 20.6N 148.7W   70 KT  80 MPH
 72H  07/0000Z 22.5N 151.1W   65 KT  75 MPH
 96H  08/0000Z 25.3N 153.3W   50 KT  60 MPH
120H  09/0000Z 28.1N 155.2W   35 KT  40 MPH

$$
Forecaster Cangialosi