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TROPICAL STORM CRISTINA DISCUSSION NUMBER  12
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT FRI JUL 12 2002
 
THE CENTER IS VERY DIFFICULT TO LOCATE ON IR IMAGERY...BUT TIMELY
SSMI OVERPASSES SUGGEST THAT THE CENTER OF CRISTINA IS STILL
ELONGATED AND PARTIALLY EXPOSED TO THE NORTHWEST OF WHAT HAS BEEN
COLD AND PERSISTENT CONVECTION.  THERE IS CONSIDERABLE SCATTER IN
SATELLITE INTENSITY ESTIMATES...WITH 35 KT FROM SAB...45 KT FROM
KGWC...AND 55 KT FROM TAFB.  MY INTERPRETATION OF THE SSMI IMAGERY
IS THAT CRISTINA IS STILL UNDER NORTHWESTERLY SHEAR AND HAS NOT
STRENGTHENED FURTHER...AND SO THE INITIAL INTENSITY FOR THIS
ADVISORY REMAINS 35 KT.  HOWEVER...RECENT AMSU-BASED PRESSURE 
ESTIMATES FROM UW/CIMSS ARE BEGINNING TO FALL...SO THE WINDS MAY 
SOON FOLLOW.  OVER THE NEXT DAY OR SO WHILE SSTS ARE STILL WARM THE 
NORTHWESTERLY SHEAR IS EXPECTED TO LESSEN...WHICH SHOULD GIVE 
CRISTINA A GOOD OPPORTUNITY TO BECOME A HURRICANE.

THE INITIAL MOTION IS 270/10.  WATER VAPOR IMAGERY SHOWS AN UPPER
CUTOFF LOW OVER SOUTHERN BAJA THAT HAS BEGUN TO DIG SOUTHWESTWARD.
GLOBAL MODELS ARE FORECASTING THE DEVELOPMENT OF A SHARP UPPER
TROUGH NEAR 120W OVER THE NEXT TWO DAYS.  SHOULD THIS OCCUR AND
CRISTINA STRENGTHEN AS EXPECTED...THE CURRENT WESTWARD TRACK COULD
TURN SHARPLY NORTHWARD.  THE AVN...UKMET...AND GFDL ARE IN VERY GOOD
AGREEMENT ON A SHARP TURN WITHIN 24 HOURS...ALTHOUGH THE MOST RECENT
AVN ENSEMBLE MEAN IS NOT AS SHARP WITH THE TURN.  THE OFFICIAL
FORECAST IS SHIFTED A LITTLE TO THE RIGHT OF THE PREVIOUS
ADVISORY...BUT IS STILL TO THE LEFT OF THE AFOREMENTIONED GUIDANCE.    

FORECASTER FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     12/0900Z 14.2N 114.0W    35 KTS
12HR VT     12/1800Z 14.3N 115.2W    45 KTS
24HR VT     13/0600Z 14.5N 116.3W    50 KTS
36HR VT     13/1800Z 15.2N 117.3W    60 KTS
48HR VT     14/0600Z 16.5N 118.0W    65 KTS
72HR VT     15/0600Z 19.0N 118.5W    50 KTS
 
 
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