- Search for Search
Tropical Depression SERGIO

ZCZC MIATCDEP1 ALL
TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION SERGIO DISCUSSION NUMBER  26
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP212006
700 PM PST SUN NOV 19 2006

DEEP CONVECTION COMES AND GOES IN SPORADIC DISORGANIZED BURSTS...BUT
RECENTLY THESE BURSTS HAVE BEEN OCCURRING MAINLY WELL TO THE EAST
OF THE CENTER.  THERE IS STILL A WELL-DEFINED...MOSTLY EXPOSED...
SWIRL OF LOW CLOUDS ASSOCIATED WITH SERGIO.  GIVEN THAT DEEP
CONVECTION HAS NOT PERSISTED NEAR THE CENTER OVER THE PAST SEVERAL
HOURS IT IS ASSUMED THE CYCLONE HAS SPUN DOWN TO BELOW TROPICAL
STORM INTENSITY.   THE SYSTEM IS LIKELY TO REMAIN IN AN ENVIRONMENT
OF STRONG WEST-SOUTHWESTERLY SHEAR OVER THE NEXT DAY OR TWO. 
OUTPUT FROM THE OPERATIONAL SHIPS MODEL SHOWS 30-35 KT OF 850-200
MB VERTICAL SHEAR AFFECTING SERGIO OVER THE NEXT 24 HOURS OR SO. 
THIS IS PROBABLY AN OVERESTIMATE OF THE SHEAR THAT WILL DIRECTLY
IMPACT THE SYSTEM...SINCE IT IS AN AVERAGE OVER A LARGE AREA THAT
INCLUDES EVEN STRONGER UPPER-LEVEL WINDS TO THE NORTH OF SERGIO.   
HOWEVER EVEN THE EXPERIMENTAL SHIPS OUTPUT...WHICH IS BASED ON THE
SHEAR AVERAGED OVER A SMALLER AREA OVER THE TROPICAL
CYCLONE...SHOWS MORE THAN 25 KT OF SHEAR DURING THE NEXT 36 HOURS. 
THIS ATMOSPHERIC ENVIRONMENT SHOULD RESULT IN CONTINUED
WEAKENING...AND SERGIO COULD DISSIPATE SOONER THAN ANTICIPATED BY
THE OFFICIAL FORECAST.

THE SYSTEM HAS BEEN MOVING SLOWLY WEST-SOUTHWESTWARD IN RESPONSE TO
THE FLOW SOUTH OF A WEAK LOW- TO MID-LEVEL HIGH PRESSURE AREA. 
THIS HIGH IS FORECAST TO SHIFT EASTWARD AND THE WEAKENING TROPICAL
CYCLONE OR ITS REMNANT IS PREDICTED TO TURN TO THE WEST AND
WEST-NORTHWEST OVER THE NEXT COUPLE OF DAYS.  THIS IS SIMILAR TO
THE PREVIOUS OFFICIAL TRACK FORECAST....BUT NOT AS FAST AS
INDICATED BY THE MEDIUM TO SHALLOW BAM GUIDANCE.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/0300Z 15.0N 106.4W    30 KT
 12HR VT     20/1200Z 14.9N 106.8W    30 KT
 24HR VT     21/0000Z 15.0N 107.7W    25 KT
 36HR VT     21/1200Z 15.3N 108.8W    25 KT...DISSIPATING
 48HR VT     22/0000Z 15.6N 110.0W    20 KT...REMNANT LOW
 72HR VT     23/0000Z...DISSIPATED
 
$$
FORECASTER PASCH
 
NNNN