Tropical Depression EIGHTEEN-E

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TROPICAL DEPRESSION EIGHTEEN-E DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP182006
200 PM PDT FRI OCT 27 2006
 
CONVENTIONAL SATELLITE IMAGERY DEPICTS A FULLY EXPOSED CIRCULATION
CENTER DISPLACED ABOUT 115 N MI SOUTHEAST OF THE RATHER LIMITED
DEEP CONVECTION.  ALTHOUGH IT IS NOT CLEAR CUT AT THIS POINT...
SOUTHEASTERLY SHEAR AS WELL AS SOME STABLE AIR INTRUSION SEEM TO BE
HAMPERING FURTHER DEVELOPMENT. AN AMBIGUITY ANALYSIS OF THIS
MORNING'S 1250Z QUIKSCAT OVERPASS INDICATED NOTHING STRONGER THAN
25 KT WIND VECTORS NEAR THE EXPOSED CENTER.  THE INITIAL INTENSITY
REMAINS AT 25 KT BASED OFF OF THE QUIKSCAT PASS AND THE DVORAK
SATELLITE CLASSIFICATIONS.

SHIPS CONTINUES TO CALL FOR SLOW STRENGTHENING...WHILE THE GFDL AND
THE GLOBAL MODELS INDICATE DISSIPATION IN 48 HOURS OR LESS. 
CONSEQUENTLY...THE INTENSITY FORECAST CALLS FOR A QUICKER DEMISE
THAN THE PREVIOUS ADVISORY...FORECASTING THE CYCLONE TO FESTER AS A
WEAK DEPRESSION FOR THE NEXT 24 HR...FOLLOWED BY WEAKENING TO A
REMNANT LOW AND DISSIPATION IN 2 DAYS.

INITIAL MOTION IS ESTIMATED AT 240/6...WITHIN THE SHALLOW
EAST-NORTHEASTERLY FLOW OF A LOW- TO MID- LEVEL RIDGE EXTENDING
FROM THE SOUTHWESTERN U.S. THROUGH THE BAJA PENINSULA.  GLOBAL
MODELS ALL SUGGEST A GENERALLY WEST-SOUTHWESTWARD MOTION THROUGH
THE FORECAST PERIOD.  HOWEVER...IF THE TROPICAL CYCLONE SURVIVES
BEYOND THE 48 HOUR PERIOD...THE MODELS DO INDICATE A DEVELOPING
BREAK IN THE RIDGE OVER THE SOUTHERN TIP OF BAJA/NORTHWEST MEXICO
WHICH WOULD CAUSE THE SYSTEM TO TURN TO THE WEST-NORTHWEST.  THE
OFFICIAL FORECAST AGREES WITH THE PREVIOUS PACKAGE AND FOLLOWS A
DYNAMICAL MODEL CONSENSUS AND THE GFS SHALLOW BAM.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/2100Z 15.6N 105.8W    25 KT
 12HR VT     28/0600Z 15.1N 106.6W    25 KT
 24HR VT     28/1800Z 14.8N 108.1W    25 KT...DISSIPATING
 36HR VT     29/0600Z 14.8N 109.6W    25 KT...REMNANT LOW
 48HR VT     29/1800Z...DISSIPATED
 
$$
FORECASTER ROBERTS/BEVEN
 
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