Tropical Depression EIGHTEEN-E
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TROPICAL DEPRESSION EIGHTEEN-E DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182013
800 PM PDT FRI NOV 01 2013
THE STRUCTURE OF THE DEPRESSION HAS CHANGED LITTLE DURING THE LAST
SEVERAL HOURS. THE CYCLONE STILL HAS AN ASYMMETRIC CONVECTIVE
PATTERN WITH NEARLY ALL OF THE DEEP CLOUDINESS CONFINED TO THE
WESTERN HALF OF THE CIRCULATION. IN ADDITION...THE CENTER IS
ELONGATED WITH MULTIPLE SWIRLS EVIDENT IN THE LAST FEW VISIBLE
IMAGES OF THE DAY. THE INITIAL WIND SPEED IS MAINTAINED AT 30
KT...IN AGREEMENT WITH THE DVORAK CLASSIFICATION FROM TAFB.
THE DEPRESSION IS MOVING SLOWLY NORTH-NORTHWESTWARD. A RIDGE
CURRENTLY OVER THE GULF OF MEXICO IS EXPECTED TO EXPAND
WESTWARD...CAUSING THE SYSTEM TO TURN TOWARD THE WEST-NORTHWEST ON
SATURDAY. THAT MOTION SHOULD BE SHORT-LIVED...HOWEVER...AS A LARGE
MID- TO UPPER-LEVEL LOW CURRENTLY NEAR 25N 125W MOVES NORTHEASTWARD.
THIS CHANGE IN THE STEERING PATTERN SHOULD CAUSE THE CYCLONE TO
TURN NORTHWARD AND THEN NORTHEASTWARD LATER IN THE WEEKEND AND
EARLY NEXT WEEK. THE NHC TRACK FORECAST BRINGS THE SYSTEM TO THE
SOUTH OF THE BAJA CALIFORNIA SUR IN ABOUT 2 DAYS AND OVER WEST-
CENTRAL MEXICO IN 2 TO 3 DAYS.
EASTERLY SHEAR OF 15-20 KT IS LIKELY THE REASON FOR THE POOR
STRUCTURE OF THE DEPRESSION. THE SHEAR IS EXPECTED TO DECREASE
DURING THE NEXT COUPLE OF DAYS WHILE THE SYSTEM REMAINS OVER WATERS
OF ABOUT 28C...AND THESE ENVIRONMENTAL CONDITIONS COULD ALLOW THE
DEPRESSION TO STRENGTHEN TO A TROPICAL STORM. WEAKENING IS FORECAST
AFTER THE CYCLONE MAKES LANDFALL...AND IT WILL LIKELY DISSIPATE
OVER THE SIERRA MADRE MOUNTAINS IN 3 TO 4 DAYS. THE NHC INTENSITY
FORECAST IS SLIGHTLY LOWER THAN THE PREVIOUS ONE...AND IS CLOSE TO
THE LATEST MODEL CONSENSUS.
FORECAST POSITIONS AND MAX WINDS
INIT 02/0300Z 16.9N 108.4W 30 KT 35 MPH
12H 02/1200Z 17.2N 109.4W 30 KT 35 MPH
24H 03/0000Z 17.9N 110.3W 35 KT 40 MPH
36H 03/1200Z 19.1N 110.5W 35 KT 40 MPH
48H 04/0000Z 21.0N 109.8W 35 KT 40 MPH
72H 05/0000Z 26.1N 106.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 06/0000Z...DISSIPATED
$$
FORECASTER CANGIALOSI
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