ZCZC MIATCDEP4 ALL
TTAA00 KNHC DDHHMM

HURRICANE NORBERT DISCUSSION NUMBER  20
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP142014
200 AM PDT SUN SEP 07 2014

Deep convection has continued to decrease significantly since the
previous advisory, and only a small area of thunderstorms exists
near the center and in the southeastern quadrant now. Due to the
rapid erosion of the convection, satellite intensity estimates have
sharply decreased, and the initial intensity of 65 kt is a
conservative blend of the TAFB, SAB, and UW-CIMSS ADT estimates.

Norbert's initial motion estimate is 290/08, a little to the left
of the previous advisory motion. No significant changes were made
to the previous forecast track, and the forecast philosophy remains
basically unchanged. During the next 72 hours, Norbert is expected
to move slowly northwestward and then northward around the western
periphery of a deep-layer ridge located over the southwestern United
States. As the cyclone weakens over colder water, the low-level
circulation is expected to remain behind to the west of the high
mountain ranges across northern Baja California, while the mid- and
upper-level circulation decouples and moves northeastward into the
southwestern United States. The official track forecast is similar
to the previous advisory track, and closely follows the multi-model
consensus TVCE.

Norbert is currently located over sub-26C sea-surface temperatures,
and the cyclone will be moving over even colder water and into a
drier and more stable air mass during the next 72 hours. The result
is that rapid weakening is forecast during the next 24 hours, with
Norbert becoming a non-convective remnant low to the west of the
northern Baja California Peninsula in 36 hours or so. The NHC
intensity forecast is close the latest IVCN multi-model consensus
and follows the rapid weakening trend indicated by the SHIPS model.

Moisture from the remnants of Dolly and the Pacific ITCZ is being
advected northward by the outer circulation of Norbert across
northern Mexico and into the southwestern United States. This could
result in heavy rains and life-threatening flash flooding in these
areas during the next few days. Please see information from your
local weather office for more details.

FORECAST POSITIONS AND MAX WINDS

INIT  07/0900Z 25.7N 116.4W   65 KT  75 MPH
 12H  07/1800Z 26.4N 117.1W   50 KT  60 MPH
 24H  08/0600Z 27.4N 117.8W   40 KT  45 MPH
 36H  08/1800Z 28.3N 118.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  09/0600Z 29.0N 117.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  10/0600Z 29.7N 116.7W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  11/0600Z 29.7N 116.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  12/0600Z...DISSIPATED

$$
Forecaster Stewart

NNNN