Hurricane LINDA
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TROPICAL DEPRESSION LINDA DISCUSSION NUMBER 13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT WED SEP 17 2003
THE LATEST QUICKSCAT PASS FOR LINDA SHOWS A BEAUTIFUL SURFACE
CIRCULATION WITH NO RAIN CONTAMINATED VALUES. THE REASON FOR THIS
IS THAT THERE IS NO DEEP CONVECTION LEFT AND THE SATELLITE SENSOR
CAN SEE THE SURFACE EVERYWHERE. THERE ARE NUMEROUS 30 KT WINDS SO
THE INTENSITY IS LOWERED TO 30 KTS IN THIS ADVISORY AND LINDA IS
DOWNGRADED TO A TROPICAL DEPRESSION.
INFRARED SATELLITE IMAGERY SHOWS COOL AND DRY AIR BEING ENTRAINED
INTO THE SYSTEM AND IS PROBABLY THE MAIN REASON FOR THE DEMISE OF
LINDA...EVEN THOUGH IT IS OVER GREATER THAN 27 DEG C WATER TEMPS.
CALCULATED VERTICAL WIND SHEAR FROM THE SHIPS MODEL IS NOT
PARTICULARLY LARGE AND WATER VAPOR IMAGERY SUPPORTS THIS.
THE INITIAL MOTION ESTIMATE IS STATIONARY. THIS HAS BEEN HINTED AT
BY THE GLOBAL MODELS WHICH WERE SLOWING THE SYSTEM DOWN. THE
DEPRESSION IS CURRENTLY LOCATED ON THE SOUTHEAST SIDE OF A LARGE
HIGH PRESSURE SYSTEM LOCATED IN THE PACIFIC OCEAN TO THE WEST OF
CALIFORNIA. THE MODELS ARE IN GOOD AGREEMENT THAT WHATEVER REMAINS
OF LINDA WILL EVENTUALLY MOVE OFF TOWARD THE SOUTHWEST AND LATER
TURN TOWARD THE WEST-SOUTHWEST UNDER THE INFLUENCE OF THIS HIGH.
THE OFFICIAL FORECAST TRACK IS ESSENTIALLY AN UPDATE OF THE
PREVIOUS OFFICIAL TRACK.
THE SHIPS MODEL CONTINUES TO WEAKEN THE SYSTEM TO A 20 KT DEPRESSION
BUT BRINGS IT BACK TO A TROPICAL STORM BY DAY 5. THE REASONS SHIPS
DOES THIS IS THAT THE TRACK WOULD KEEP THE SYSTEM OVER GREATER THAN
27 DEG C SSTS AND THE VERTICAL SHEAR GETS SMALLER WITH TIME.
HOWEVER...IF THE SYSTEM CONTINUES TO ENTRAIN THE DRY COOL AIR TO
THE NORTH IT WILL NOT MAKE IT BACK. THE INTENSITY FORECAST KEEPS
LINDA AS A 25 KT DEPRESSION OUT TO DAY 5...BUT IF NO DEEP
CONVECTION RETURNS SOON IT WILL BECOME A REMNANT LOW.
FORECASTER JARVINEN
FORECAST POSITIONS AND MAX WINDS
INITIAL 17/0900Z 20.6N 116.5W 30 KT
12HR VT 17/1800Z 20.2N 117.0W 25 KT
24HR VT 18/0600Z 19.7N 117.7W 25 KT
36HR VT 18/1800Z 19.0N 118.7W 25 KT
48HR VT 19/0600Z 18.7N 119.9W 25 KT
72HR VT 20/0600Z 18.4N 121.7W 25 KT
96HR VT 21/0600Z 18.3N 123.0W 25 KT
120HR VT 22/0600Z 18.2N 124.5W 25 KT
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