000
WTNT42 KNHC 162040
TCDAT2
HURRICANE JULIA DISCUSSION NUMBER  19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL122010
500 PM AST THU SEP 16 2010
 
VERTICAL SHEAR APPEARS TO HAVE ABATED FOR THE MOMENT...WITH A 1533
UTC AMSR-E MICROWAVE PASS SHOWING THAT THE LOW- AND MID-LEVEL
CENTERS ARE JUST ABOUT VERTICALLY STACKED.  HOWEVER...CONVECTIVE
TOPS HAVE WARMED...AND SATELLITE CURRENT INTENSITY ESTIMATES ARE
NOW 77 KT FROM TAFB...65 KT FROM SAB...AND 65 KT AND 80 KT FROM TWO
VERSIONS OF THE UW-CIMSS ADT.  THE INITIAL INTENSITY IS THEREFORE
LOWERED TO 75 KT FOR THIS ADVISORY.
 
JULIA HAS AN INITIAL MOTION OF 295/22 KT.  THERE HAS BEEN A
SIGNIFICANT WESTWARD SHIFT IN NEARLY ALL THE TRACK GUIDANCE ON THIS
CYCLE...POSSIBLY DUE TO A STRONGER-THAN-EXPECTED MID-LEVEL HIGH TO
THE NORTH AND NORTHEAST OF THE HURRICANE.  CONSEQUENTLY...THE NEW
OFFICIAL FORECAST HAS BEEN SHIFTED WESTWARD ABOUT HALFWAY BETWEEN
OFCI AND THE MODEL CONSENSUS TVCN.  SEVERAL MODELS...ESPECIALLY THE
UKMET AND ECMWF...ARE EVEN FARTHER WEST THAN THIS TRACK SO IT IS
POSSIBLE THAT ADDITIONAL SHIFTS COULD BE REQUIRED IN THE NEXT FEW
ADVISORY PACKAGES.  GLOBAL MODEL FIELDS INDICATE THAT AFTER JULIA
MOVES NORTHWARD AROUND THE RIDGE...IT SHOULD TURN TOWARD THE
NORTHEAST AND DISSIPATE IN THE STRONG SOUTHWESTERLY FLOW TO THE 
EAST OF IGOR IN ABOUT 120 HOURS.
 
WITH THE WESTWARD SHIFT IN THE FORECAST TRACK...JULIA APPEARS TO
HAVE A BETTER CHANCE TO MAINTAIN SOME OF ITS INTENSITY OVER THE
NEXT COUPLE OF DAYS.  THE HURRICANE WILL BE BATTLING THE STRONG
UPPER-LEVEL OUTFLOW OF IGOR DURING THE NEXT 36 HOURS OR SO...BUT
AFTER THAT THE GLOBAL MODELS SUGGEST THAT JULIA COULD SNEAK
UNDERNEATH THE UPPER-LEVEL ANTICYCLONE PARTIALLY GENERATED BY IGOR.
THE SHEAR COULD RELAX JUST ENOUGH DURING THAT TIME AND CAUSE MORE
MODEST WEAKENING...SO THE NEW INTENSITY FORECAST IS A LITTLE BIT
HIGHER THAN THE PREVIOUS ONE FROM 36-72 HOURS.  INCIDENTALLY... THE
NEW FORECAST IS STILL LOWER THAN INDICATED BY THE LGEM...THE
DYNAMICAL MODELS...AND THE INTENSITY CONSENSUS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/2100Z 23.1N  41.1W    75 KT
 12HR VT     17/0600Z 24.2N  43.9W    65 KT
 24HR VT     17/1800Z 26.0N  47.1W    65 KT
 36HR VT     18/0600Z 27.9N  49.6W    60 KT
 48HR VT     18/1800Z 30.1N  51.0W    55 KT
 72HR VT     19/1800Z 34.0N  50.5W    45 KT
 96HR VT     20/1800Z 37.0N  47.0W    35 KT
120HR VT     21/1800Z...DISSIPATED
 
$$
FORECASTER BERG