Tropical Storm MIRIAM

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TROPICAL STORM MIRIAM DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP142006
200 PM PDT SAT SEP 16 2006
 
SATELLITE IMAGERY DURING THE DAY INDICATES THAT TROPICAL DEPRESSION
14E HAS A PARTLY EXPOSED LOW-LEVEL CENTER JUST TO THE NORTHEAST OF
THE MAIN CONVECTION.  WHILE THE CONVECTION IS CURRENTLY
WEAKENING...SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB WERE
AGAIN 35 KT AT 18Z.  ON THIS BASIS...THE CYCLONE IS UPGRADED TO
TROPICAL STORM MIRIAM WITH 35 KT WINDS.  THE MEXICAN NAVY AUTOMATED
STATION ON CLARION ISLAND...OUTSIDE OF THE MAIN CONVECTION...HAS
BEEN REPORTING SUSTAINED WINDS NEAR 25 KT WITH GUSTS OF 30-35 KT
DURING THE DAY WITH PRESSURES OF 1005-1006 MB.

THE INITIAL MOTION IS A HIGLY UNCERTAIN 040/3.  THE DEPRESSION
SHOULD MOVE NORTHEASTWARD FOR THE NEXT 24-36 HR AS IT IS CAUGHT IN
SOUTHWESTERLY FLOW FEEDING INTO HURRICANE LANE.  AFTER THAT...LANE
SHOULD BE DISSIPATING OVER MEXICO...AND ENOUGH RIDGING SHOULD
DEVELOP NORTH AND NORTHEAST OF THE CYCLONE TO TURN IT TO A
NORTHWESTERLY TRACK.  THE LATEST TRACK GUIDANCE SHOWS AN INCREASED
CHANCE THAT AFTER 96 HR THE SYSTEM COULD TURN NORTHWARD IN RESPONSE
TO A MID/UPPER-LEVEL SHORTWAVE TROUGH EXTENDING SOUTHWESTWARD FROM
SOUTHERN CALIFORNIA...SO A NORTHWARD TURN IS NOW INDICATED AT THAT
TIME.

A COMBINATION OF NORTHEASTERLY VERTICAL WIND SHEAR...STABLE
INFLOW...AND GRADUALLY COOLING SEA SURFACE TEMPERATURES ALONG THE
FORECAST TRACK WILL LIKELY KEEP MIRIAM FROM STRENGTHENING VERY
MUCH.  THE INTENSITY FORECAST NOW CALLS FOR A LITTLE STRENGTHENING
NEAR 48 HR WHEN THE SHEAR IS FORECAST TO DECREASE SOMEWHAT.  AFTER
THAT...THE SYSTEM SHOULD WEAKEN OVER COOLER WATERS AND BECOME A
REMNANT LOW BY 120 HR.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/2100Z 18.2N 114.3W    35 KT
 12HR VT     17/0600Z 18.7N 113.7W    35 KT
 24HR VT     17/1800Z 19.7N 113.0W    35 KT
 36HR VT     18/0600Z 20.9N 112.5W    35 KT
 48HR VT     18/1800Z 22.1N 112.9W    40 KT
 72HR VT     19/1800Z 23.5N 114.5W    35 KT
 96HR VT     20/1800Z 25.5N 115.5W    25 KT...DISSIPATING
120HR VT     21/1800Z 27.5N 115.5W    20 KT...REMNANT LOW
 
$$
FORECASTER BEVEN
 
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