Tropical Depression FOURTEEN-E

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TROPICAL DEPRESSION FOURTEEN-E DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP142008
200 AM PDT WED OCT 01 2008
 
SATELLITE IMAGERY AND QUIKSCAT DATA INDICATE THAT THE LOW PRESSURE
AREA SOUTH-SOUTHWEST OF BAJA CALIFORNIA HAS DEVELOPED A
WELL-DEFINED SURFACE CIRCULATION AND SUFFICIENT ORGANIZED
CONVECTION TO BE DESIGNATED A TROPICAL DEPRESSION.  THE QUIKSCAT
DATA SHOWED RELIABLE-LOOKING WINDS OF 25-30 KT SOUTHEAST OF THE
CENTER...WITH RAIN-CONTAMINATED WINDS OF UP TO 45 KT SOUTHWEST OF
THE CENTER.  SATELLITE INTENSITY ESTIMATES ARE 45 KT FROM TAFB AND
30 KT FROM SAB.  BASED ON THE QUIKSCAT DATA...THE INITIAL INTENSITY
IS SET AT 30 KT.  THE DEPRESSION IS CURRENTLY EXPERIENCING ABOUT
20 KT OF EASTERLY VERTICAL WIND SHEAR...AND AS A RESULT THE CENTER
IS NEAR THE EASTERN EDGE OF THE MAIN CONVECTION.

THE INITIAL MOTION IS 295/8.  THE DEPRESSION IS ON THE SOUTHWEST
SIDE OF A MID/UPPER-LEVEL RIDGE OVER NORTHWESTERN MEXICO...WHICH
SHOULD STEER THE SYSTEM GENERALLY WEST-NORTHWESTWARD FOR THE NEXT
48 HR OR SO.  AFTER THAT...THE LARGE-SCALE MODELS FORECAST A LARGE
DEEP-LAYER TROUGH TO MOVE INTO THE WESTERN UNITED STATES...WITH A
BREAK DEVELOPING IN THE RIDGE.  WHILE THE MODELS AGREE ON THE
PATTERN...THEY DIVERGE ON THE TRACK OF THE TROPICAL CYCLONE.  THE
GFS...HWRF...AND GFDL KEEP ENOUGH RIDGE BETWEEN THE CYCLONE AND THE
TROUGH FOR THE CYCLONE TO MOVE WESTWARD.  ON THE OTHER HAND...THE
LBAR...NOGAPS...UKMET...AND ECMWF CREATE A BIG ENOUGH BREAK TO TURN
THE TROPICAL CYCLONE SLOWLY NORTHWARD.  IT IS UNCLEAR AT THIS TIME
WHICH OF THESE TWO OPTIONS IS MOST LIKELY TO HAPPEN.  THUS...THE
FORECAST TRACK AFTER 48 HR CALLS FOR A SLOW WESTWARD MOTION AS A
COMPROMISE BETWEEN THE TWO EXTREMES.

THE LARGE-SCALE MODELS FORECAST THE CURRENT SHEAR TO DIMINISH DURING
THE NEXT 48 HR...WHICH SHOULD ALLOW SOME STRENGTHENING.  THE MAIN
LIMITING FACTOR IS THAT THE CYCLONE WILL MOVE OVER DECREASING SEA
SURFACE TEMPERATURES DURING THE FORECAST PERIOD...REACHING THE
26C ISOTHERM BY DAY 5.  NONE OF THE INTENSITY GUIDANCE FORECASTS
STRENGTHENING BEYOND ABOUT 50 KT...WHICH IS A LITTLE PUZZLING SINCE
THE SHEAR IS LIKELY TO DECREASE WHILE THE CYCLONE IS STILL OVER
WARM WATER.  THE INTENSITY FORECAST GENERALLY FOLLOWS THE SHIPS
MODEL THROUGH 48 HR...THEN CALLS FOR A WEAKER SYSTEM THAN SHIPS DUE
TO THE COOLING SSTS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      01/0900Z 16.3N 115.7W    30 KT
 12HR VT     01/1800Z 17.0N 116.8W    35 KT
 24HR VT     02/0600Z 17.7N 118.3W    40 KT
 36HR VT     02/1800Z 18.1N 119.7W    45 KT
 48HR VT     03/0600Z 18.1N 121.0W    45 KT
 72HR VT     04/0600Z 18.0N 123.0W    45 KT
 96HR VT     05/0600Z 18.0N 124.5W    40 KT
120HR VT     06/0600Z 18.0N 126.5W    35 KT
 
$$
FORECASTER BEVEN
 
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