125 
 WTNT42 KNHC 040852
 TCDAT2
  
 TROPICAL STORM KATIA DISCUSSION NUMBER  25
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122011
 500 AM AST SUN SEP 04 2011
  
 KATIA REMAINS IN A NEARLY STEADY STATE. THE CLOUD PATTERN CONTINUES
 TO CONSIST OF A RATHER INDISTINCT CENTRAL DENSE OVERCAST WHICH HAS
 BEEN PULSATING SOMEWHAT FREQUENTLY. A COUPLE OF MICROWAVE PASSES
 SHOWED THE EXISTENCE OF A MID-LEVEL EYE THAT HAS BEEN LESS DEFINED
 IN THE LOW-LEVELS. WITH ESSENTIALLY NO STRUCTURAL CHANGES TO REPORT
 AND DVORAK T-NUMBERS THE SAME AS AT 0000 UTC...THE INITIAL
 INTENSITY IS HELD AT 60 KT. CIRRUS CLOUD MOTIONS AND UW-CIMSS
 ANALYSES SUGGEST A SOUTHWESTERLY FLOW UNDERCUTTING THE OUTFLOW
 LAYER...WHICH MAY HAVE BEEN STALLING THE INTENSIFICATION PROCESS.
 GLOBAL MODELS CONTINUE TO INSIST ON A MORE CONDUCIVE UPPER AIR
 FORECAST AHEAD OF KATIA THAT WOULD FAVOR INTENSIFICATION BEGINNING
 IN A COUPLE OF DAYS. THEN AGAIN...THE FORECAST REDUCTION IN SHEAR
 BY THIS TIME HAS NOT MATERIALIZED AND IT WOULD SEEM THAT THE MODELS
 HAVE CONTINUALLY UNDERFORECAST THE AMOUNT OF SHEAR. THE OFFICIAL
 FORECAST WILL KEEP THIS IN MIND AND REPRESENT A MEASURED
 APPROACH...BLENDING THE MORE RELIABLE STATISTICAL MODELS INDICATING
 MODEST STRENGTHENING AND DYNAMICAL GUIDANCE WHICH STILL FORECASTS
 KATIA TO BECOME A MAJOR HURRICANE.
  
 LOCATING THE CENTER HAS BEEN DIFFICULT IN CONVENTIONAL SATELLITE
 IMAGERY...BUT A TIMELY AMSR-E PASS HELPED TO ESTABLISH THE INITIAL
 MOTION ESTIMATE OF 305/10.  WATER VAPOR IMAGERY SHOWS KATIA HEADING
 NORTHWESTWARD TOWARD A MID- TO UPPER-LEVEL IMPULSE LOCATED OVER THE
 WESTERN ATLANTIC.  ALTHOUGH THE LARGE-SCALE MODELS FORECAST THIS
 FEATURE TO LIFT OUT DURING THE NEXT DAY OR TWO...THEY ALSO FORECAST
 A WEAKNESS OVER THIS REGION TO REMAIN IN PLACE WHICH SHOULD CAUSE
 KATIA TO CONTINUE ON A NORTHWESTWARD COURSE AND SLOW DURING THE
 NEXT SEVERAL DAYS.  THE LONGER-TERM TRACK OF KATIA SEEMS DEPENDENT
 ON THE TROUGH ASSOCIATED WITH THE REMNANTS OF LEE AND A PROCESSION
 OF SHORTWAVE TROUGHS MOVING THROUGH THE NORTHEASTERN UNITED
 STATES...BOTH OF WHICH THE MODELS ARE HANDLING DIFFERENTLY TO
 VARYING DEGREES.  THERE HAS BEEN A SIGNIFICANT WESTWARD SHIFT IN
 THE GUIDANCE THIS CYCLE...ALONG WITH A NOTABLE INCREASE IN THE
 SPREAD.  THE OFFICIAL TRACK AT THIS LONGER RANGE IS OF SOMEWHAT
 LOWER CONFIDENCE...GIVEN THE SPREAD...AND IS ADJUSTED TO THE
 LEFT...BUT NOT AS FAR LEFT AS THE LATEST MULTI-MODEL CONSENSUS.
  
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  04/0900Z 21.4N  58.5W   60 KT  70 MPH
  12H  04/1800Z 22.3N  59.8W   65 KT  75 MPH
  24H  05/0600Z 23.5N  61.6W   70 KT  80 MPH
  36H  05/1800Z 24.7N  63.5W   75 KT  85 MPH
  48H  06/0600Z 25.8N  65.0W   80 KT  90 MPH
  72H  07/0600Z 27.7N  68.0W   85 KT 100 MPH
  96H  08/0600Z 30.0N  71.0W   90 KT 105 MPH
 120H  09/0600Z 32.5N  72.0W   85 KT 100 MPH
  
 $$
 FORECASTER KIMBERLAIN