Hurricane SERGIO

ZCZC MIATCDEP1 ALL
TTAA00 KNHC DDHHMM
HURRICANE SERGIO DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP212006
700 PM PST THU NOV 16 2006
 
AFTER WEAKENING CONSIDERABLY EARLIER TODAY...SERGIO APPEARS TO BE
HOLDING ITS OWN AS DEEP CONVECTION HAS REFORMED OVER THE CENTER.
THE INITIAL INTENSITY IS HELD AT 70 KT BASED ON THIS TREND.
NONETHELESS...THE CYCLONE CONTINUES TO BATTLE STRONG WESTERLY
SHEAR...AND WATER VAPOR IMAGERY SUGGESTS THE SHEAR WILL BE EVEN
STRONGER ALONG THE PROJECTED TRACK. EVEN THE GFDL HAS FINALLY
ACKNOWLEDGED SUCH A HOSTILE ENVIRONMENT AND BACKED OFF FROM ITS
EARLIER ROBUST INTENSIFICATION. THE ONLY POTENTIAL FACTOR ARGUING
FOR STRENGTHENING WOULD BE FOR THE UPPER-LEVEL TROUGH CURRENTLY TO
THE NORTHWEST OF THE CYCLONE TO FRACTURE AND FORM A CLOSED
LOW...LEAVING A DOWNSTREAM UPPER-LEVEL RIDGE OVER SERGIO. SOME OF
THE GLOBAL MODELS SUGGEST SUCH A LARGE-SCALE ENVIRONMENT COULD
UNFOLD IN 1-2 DAYS. HOWEVER...EVEN IF THIS PATTERN MATERIALIZES...
SERGIO WOULD STILL HAVE TO OVERCOME INCREASINGLY DRY AND STABLE
AIR. THE OFFICIAL FORECAST ASSUMES THAT SERGIO WILL GRADUALLY
WEAKEN...BUT IT DOES PAY RESPECT TO THE POTENTIALLY LESS
HOSTILE UPPER-LEVEL WINDS BY SHOWING AN INTENSITY PLATEAU AT 36-48
HOURS. THE FSU SUPERENSEMBLE AND SHIPS MODELS SHOW EVEN FASTER
WEAKENING THAN INDICATED HERE. 
 
SERGIO CONTINUES ITS GRADUAL TURN TOWARD THE NORTH WITH AN INITIAL
MOTION ESTIMATE OF 360/4.  THERE HAS BEEN LITTLE CHANGE IN THE
OVERALL FORECAST TRACK PHILOSOPHY.  A MID-LEVEL RIDGE IS EXPECTED
TO BUILD SOUTHWARD OVER CENTRAL MEXICO DURING THE NEXT DAY OR SO
IMPARTING A TURN TOWARD THE NORTHWEST.  HOWEVER...THIS PATTERN WILL
ALSO PRODUCE LARGE DISCREPANCIES BETWEEN THE DEEP AND SHALLOW LAYER
STEERING FLOWS.  ACCORDINGLY...THERE REMAINS CONSIDERABLE SPREAD
AMONG THE VARIOUS TRACK MODELS.  A STRONGER AND DEEPER CYCLONE
WOULD TEND TO TRACK ALONG THE RIGHT SIDE OF THE GUIDANCE ENVELOPE
IN LINE WITH THE NOGAPS...GFDL...AND DEEP BAM MODELS.
CONVERSELY...A WEAKER AND MORE SHALLOW SYSTEM WOULD TEND TO MOVE
CLOSER TO THE LEFT SIDE OF THE GUIDANCE ENVELOPE IN LINE WITH THE
GFS...ITS ENSEMBLE MEAN...AND THE SHALLOW BAM MODELS.  IT IS HARD
TO IMAGINE SERGIO REMAINING A HURRICANE MUCH LONGER IN LIGHT OF THE
AFOREMENTIONED HOSTILE ENVIRONMENT.  ACCORDINGLY...THE OFFICIAL
FORECAST LEANS A LITTLE TO THE LEFT OF THE MODEL CONSENSUS. 
 
SERGIO IS AN EXCELLENT REMINDER THAT THE EFFECTS OF A HURRICANE CAN
EXTEND FAR FROM THE CENTER...AS RAINBANDS EXTEND WELL TO THE
NORTHEAST AND HAVE BEEN AFFECTING COASTAL PORTIONS OF SOUTHWESTERN
MEXICO TODAY. IT IS FOR THIS REASON...AND THE HIGHER THAN NORMAL
FORECAST UNCERTAINTY...THAT INTERESTS IN MEXICO SHOULD CLOSELY
MONITOR THE PROGRESS OF SERGIO.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0300Z 13.8N 102.7W    70 KT
 12HR VT     17/1200Z 14.5N 102.9W    65 KT
 24HR VT     18/0000Z 15.1N 103.4W    60 KT
 36HR VT     18/1200Z 15.8N 104.2W    55 KT
 48HR VT     19/0000Z 16.7N 105.0W    55 KT
 72HR VT     20/0000Z 18.0N 106.5W    45 KT
 96HR VT     21/0000Z 19.5N 108.5W    35 KT
120HR VT     22/0000Z 21.5N 111.0W    25 KT...REMNANT LOW
 
$$
FORECASTER RHOME
 
NNNN