Tropical Storm SERGIO

ZCZC MIATCDEP1 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM SERGIO DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP212006
100 PM PST TUE NOV 14 2006
 
THE SATELLITE APPEARANCE OF SERGIO CONTINUES TO IMPROVE WITH A
DISTINCT CURVED BANDING FEATURE WRAPPING AROUND THE WESTERN
SEMICIRCLE OF THE STORM.  DVORAK INTENSITY ESTIMATES FROM BOTH TAFB
AND SAB WERE 45 KT AT 1800 UTC.  SINCE THEN...THE BANDING FEATURE
AND OVERALL STRUCTURE OF THE STORM HAVE BECOME BETTER DEFINED AND
IT APPEARS THAT AN EYE IS TRYING TO FORM.  THE INITIAL INTENSITY IS
SET AT 50 KT FOR THIS ADVISORY.
 
SERGIO HAS MOVED LITTLE TODAY...AND RECENTLY HAS BEEN DRIFTING
SLIGHTLY SOUTHWARD.  LITTLE MOTION IS ANTICIPATED DURING THE NEXT
COUPLE OF DAYS AS MOST OF THE DYNAMICAL MODEL GUIDANCE PREDICTS THE
CURRENTLY WEAK STEERING PATTERN TO PERSIST.  AFTER THAT...THE TRACK
GUIDANCE DIVERGES.  ONE SCENARIO...FAVORED BY THE UKMET AND
NOGAPS...MAINTAINS A WEAK STEERING PATTERN AND MEANDERS SERGIO OFF
THE WEST COAST OF CENTRAL MEXICO.  A SECOND SCENARIO...OFFERED BY
THE GFDL...ECMWF...AND FSSE...TAKES THE CYCLONE NORTHWARD IN
RESPONSE TO A MID- TO UPPER-LEVEL LOW FORECAST TO MOVE SOUTHWARD
WEST OF THE BAJA COAST.  THE OFFICIAL FORECAST FOLLOWS THE SECOND
OPTION AND IS JUST EAST OF AND SLOWER THAN THE PREVIOUS PACKAGE.
 
THE TROPICAL CYCLONE IS IN A FAVORABLE ENVIRONMENT FOR ADDITIONAL
STRENGTHENING...POSSIBLY RAPID...WITH LIGHT UPPER-LEVEL WINDS AND A
WARM DEEP OCEAN.  THE GFDL IS THE MOST ROBUST OF THE INTENSITY
GUIDANCE AND MAKES SERGIO A MAJOR HURRICANE IN THREE DAYS. ON THE
OTHER HAND...THE SHIPS INTENSITY GUIDANCE IS MORE CONSERVATIVE...
TAKING THE CYCLONE ONLY TO 70 KT IN 2 DAYS DUE TO AN INCREASE IN
SHEAR.  THE OFFICIAL FORECAST IS A BLEND OF THE TWO EXTREMES...AND
IS ADJUSTED UPWARD FROM THE PREVIOUS GUIDANCE.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/2100Z 12.8N 104.5W    50 KT
 12HR VT     15/0600Z 13.0N 104.7W    60 KT
 24HR VT     15/1800Z 13.1N 104.8W    70 KT
 36HR VT     16/0600Z 13.3N 104.9W    80 KT
 48HR VT     16/1800Z 14.0N 105.0W    80 KT
 72HR VT     17/1800Z 15.5N 105.0W    80 KT
 96HR VT     18/1800Z 16.5N 105.5W    75 KT
120HR VT     19/1800Z 18.0N 106.5W    70 KT
 
$$
FORECASTER MAINELLI
 
NNNN