000
WTNT42 KNHC 190233
TCDAT2
TROPICAL STORM JULIA DISCUSSION NUMBER  28
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL122010
1100 PM AST SAT SEP 18 2010
 
JULIA HAS MOVED INTO A REGION OF WEAKER VERTICAL SHEAR DURING THE
PAST 6 HOURS AND VERY COLD TOPPED CONVECTION HAS DEVELOPED NEAR AND
SOUTHEAST OF THE LOW-LEVEL CENTER AS A RESULT. SATELLITE CURRENT
INTENSITY ESTIMATES ARE T3.5/55 KT FROM TAFB...T2.5/35 KT FROM
SAB...AND ADT VALUES OF T3.4/43 KT FROM UW-CIMSS...RESPECTIVELY.
GIVEN THE NEW DEVELOPMENT OF DEEP CONVECTION NEAR THE CENTER...THE
INITIAL INTENSITY REMAINS 45 KT...WHICH IS AN AVERAGE OF THE THREE
INTENSITY ESTIMATES.

JULIA HAS TURNED TOWARD THE NORTH AND IS NOW ESTIMATED TO BE MOVING
AT 360/12. JULIA EARLIER ACCELERATED NORTHWARD AT ABOUT 20 KT
DURING THE PERIOD WHEN IT POSSESSED NO DEEP CONVECTION NEAR THE
CENTER. HOWEVER...NOW THAT CONVECTION HAS REFORMED...THE
CIRCULATION HAS LIKELY DEEPENED IN THE VERTICAL AND WILL BE SUBJECT
TO A DEEPER AND SLOWER STEERING FLOW. THE NHC MODEL GUIDANCE IS IN
GENERAL AGREEMENT ON JULIA MOVING NORTHWARD FOR THE NEXT 12 HOURS
AND THEN NORTHEASTWARD AFTER THAT AS THE CYCLONE MOVES AROUND THE
WESTERN PERIPHERY OF A LARGE SUBTROPICAL RIDGE LOCATED TO ITS EAST.
BY 48 HOURS...A SEVERELY WEAKENED AND SHALLOW JULIA AT THAT TIME IS
EXPECTED TO GRADUALLY BECOME ABSORBED INTO THE EASTERN PORTION OF
THE VERY LARGE HURRICANE IGOR CIRCULATION. THE OFFICIAL FORECAST IS
A LITTLE TO THE LEFT OF THE PREVIOUS ADVISORY TRACK...AND IS
SIMILAR TO THE CONSENSUS MODELS...TVCN AND TVCC.

WEAKER VERTICAL SHEAR CONDITIONS THAT JULIA HAS BEEN EXPERIENCING
THE PAST 6 HOURS WILL BE SHORT-LIVED SINCE THE CYCLONE WILL BE
MOVING NORTHWARD INTO A REGION OF STRONG WESTERLY SHEAR OF 30-50 KT
EMANATING FROM THE MASSIVE OUTFLOW FROM HURRICANE IGOR IN 6-12
HOURS. BY 24 HOURS...JULIA WILL ALSO BE MOVING OVER SUB-26C
SSTS...WHICH WHEN COMBINED WITH THE INCREASING WESTERLY SHEAR...
SHOULD INDUCE RAPID WEAKENING. JULIA IS EXPECTED TO BECOME A
REMNANT LOW IN 36-48 HOURS...IF NOT SOONER. THE OFFICIAL INTENSITY
FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY...AND CLOSELY FOLLOWS
THE SHIPS/LGEM MODELS...WHICH DISSIPATE JULIA BY AROUND 48 HOURS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/0300Z 32.4N  51.9W    45 KT
 12HR VT     19/1200Z 34.3N  51.7W    40 KT
 24HR VT     20/0000Z 36.1N  50.4W    30 KT
 36HR VT     20/1200Z 37.6N  48.7W    25 KT
 48HR VT     21/0000Z 39.1N  46.9W    25 KT...POST-TROP/REMNT LOW
 72HR VT     22/0000Z 43.6N  41.8W    20 KT...POST-TROP/REMNT LOW
 96HR VT     23/0000Z...DISSIPATED
 
$$
FORECASTER STEWART