Tropical Depression MIRIAM

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TROPICAL DEPRESSION MIRIAM DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP142006
200 AM PDT MON SEP 18 2006
 
MIRIAM HAS BEEN VOID OF DEEP CONVECTION SINCE ABOUT 0100 UTC. A 0154
UTC QUIKSCAT PASS SHOWED ONLY A SINGLE 35 KT VECTOR SOUTHEAST OF
THE CENTER...AND IT IS ASSUMED THAT THE WINDS HAVE SINCE DECREASED
DUE TO THE LACK OF CONVECTION. THEREFORE...MIRIAM IS BEING
DOWNGRADED TO A TROPICAL DEPRESSION. AS THE CYCLONE MOVES OVER
PROGRESSIVELY COOLER WATER AND INTO A MORE STABLE ENVIRONMENT...THE
PROSPECTS FOR THE REDEVELOPMENT OF CONVECTION WILL DIMINISH...AND
THE CYCLONE SHOULD BECOME A REMNANT LOW LATER TODAY. MIRIAM HAS A
LARGE LOW-LEVEL CIRCULATION THAT COULD PERSIST FOR SEVERAL DAYS
PRIOR TO DISSIPATION.
 
SHORTWAVE INFRARED IMAGERY AND MICROWAVE DATA SUGGEST THAT THE
CENTER OF MIRIAM HAS BEEN MOVING JUST TO THE EAST OF DUE NORTH...
AROUND 010/05...TO THE RIGHT OF THE PREVIOUS TRACK.  THE TRACK IS
SHIFTED TO THE RIGHT OF THE PREVIOUS FORECAST...AND THE HEADING AND
SPEED FOLLOW THE TREND OF THE SHALLOW BAM MODEL.  THIS TRACK IS TO
THE RIGHT OF MOST OF THE GLOBAL MODEL GUIDANCE...WHICH INITIALIZED
MIRIAM AS A DEEPER SYSTEM.  THE REMNANT CIRCULATION OF MIRIAM WILL
BE STEERED TOWARD THE NORTH-NORTHWEST AND EVENTUALLY ACCELERATE
TOWARD THE NORTH AND NORTHEAST AS IT MOVES AROUND THE WESTERN
PERIPHERY OF THE LOWER-TROPOSPHERIC RIDGE CENTERED OVER MEXICO
DURING THE NEXT FEW DAYS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/0900Z 19.9N 113.7W    30 KT
 12HR VT     18/1800Z 20.9N 114.1W    30 KT...REMNANT LOW
 24HR VT     19/0600Z 22.2N 114.9W    25 KT...REMNANT LOW
 36HR VT     19/1800Z 24.4N 116.0W    25 KT...REMNANT LOW
 48HR VT     20/0600Z 26.7N 116.4W    25 KT...REMNANT LOW
 72HR VT     21/0600Z 30.5N 114.5W    20 KT...REMNANT LOW
 96HR VT     22/0600Z...DISSIPATED
 
$$
FORECASTER BRENNAN/FRANKLIN
 
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