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000
WTPZ41 KNHC 230846
TCDEP1

HURRICANE KARINA DISCUSSION NUMBER  42
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP112014
200 AM PDT SAT AUG 23 2014

Karina continues to show signs of an intermittent eye in shortwave
and longwave IR imagery.  Dvorak estimates from TAFB, SAB, and
UW-CIMSS are unchanged since the last advisory, and several recent
AMSU passes have indicated an intensity of 70 to 75 kt.  Based on
these data, the initial intensity is held at 70 kt.  No significant
change to the intensity forecast was made.  Karina continues to
march steadily toward cooler SSTs and a subsequently more stable
thermodynamic environment.  After 36 hours, the cyclone should
encounter an increasingly dry mid-level environment and higher
shear, resulting in an increased rate of weakening.  Most of the
dynamical models forecast that the low- and mid-level centers will
become decoupled within 96 hours, but that the low-level center
will persist for a day or two after that.

The hurricane is moving toward the northwest at about 7 kt. There
remains a high degree of confidence for the first 48 hours of the
track forecast. A general east-northeastward track is still
expected while Karina interacts with the circulation of Lowell.
After Lowell passes to the north, there is a considerable amount of
uncertainty regarding the track of Karina and its remnants.  Not
only is the model spread very large, but the run-to-run consistency
has been remarkably poor. For instance, the 00Z and 18Z GFS 120-h
forecast positions differ by over 700 nm.  The members of TVCE
currently support three very distinct scenarios.  The GFS shows
Karina wrapping around to the north side of Lowell and moving
rapidly westward. The HWRF and GFDL models show a slower westward
motion, caused by a mid-level ridge that is forecast to build to the
east of Lowell. Finally, the ECMWF and UKMET forecast that Karina
will be advected southward by the circulation of Marie. The official
forecast has been shifted slightly northward, in part due to the
extreme shift of the GFS, but remains closest to the middle ground
solution of the HWRF and GFDL.  If the models begin to converge on a
single solution, it may necessitate a larger change to the forecast.


FORECAST POSITIONS AND MAX WINDS

INIT  23/0900Z 16.7N 134.4W   70 KT  80 MPH
 12H  23/1800Z 17.4N 133.6W   65 KT  75 MPH
 24H  24/0600Z 18.0N 132.2W   60 KT  70 MPH
 36H  24/1800Z 18.6N 130.6W   55 KT  65 MPH
 48H  25/0600Z 19.2N 129.3W   45 KT  50 MPH
 72H  26/0600Z 20.6N 129.2W   35 KT  40 MPH
 96H  27/0600Z 21.5N 131.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  28/0600Z 22.0N 133.0W   20 KT  25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Zelinsky/Brown



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