726 
 WTNT42 KNHC 261506
 TCDAT2
 HURRICANE KATRINA DISCUSSION NUMBER  12
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 11 AM EDT FRI AUG 26 2005
  
 RECENT DATA FROM AN AIR FORCE RECON AIRCRAFT INDICATES KATRINA'S
 CENTRAL PRESSURE IS MUCH LOWER...NOW AT 971 MB. MAXIMUM 700 MB
 FLIGHT-LEVEL WINDS ARE 81 KT IN THE NORTHWEST QUADRANT...WHICH
 SUPPORTS AT LEAST 70 KT SURFACE WINDS. HOWEVER...THE AIRCRAFT HAS
 NOT SAMPLED THE WINDS IN THE EASTERN SEMICIRCLE WHERE NOAA/KEY WEST
 DOPPLER RADAR VELOCITY DATA INDICATES WINDS AS HIGH AS 91 KT AT
 AROUND 3000 FT...WHICH WOULD SUPPORT A SURFACE WIND ESTIMATE OF
 ABOUT 75 KT. THE INITIAL INTENSITY OF 70 KT MAY TURN OUT TO BE A
 LITTLE LOW.
  
 THE INITIAL MOTION ESTIMATE IS 265/6. RADAR DATA INDICATES KATRINA
 HAS CONTINUED TO MOVE SOUTH OF DUE WEST DURING THE PAST 6 HOURS.
 MOST OF THE NHC MODEL GUIDANCE INDICATES THE TRACK SHOULD FLATTEN
 OUT IN A MORE WESTWARD DIRECTION DURING THE NEXT 12 HOURS AS THE
 INFLUENCE OF AN INVERTED TROUGH OVER THE CARIBBEAN SEA DECREASES.
 THE MID-LEVEL SUBTROPICAL RIDGE TO THE NORTH AND NORTHWEST OF
 KATRINA IS FORECAST BY THE ALL GLOBAL AND REGIONAL MODELS TO
 GRADUALLY WEAKEN THROUGH THE FORECAST PERIOD AS A STRONG SHORTWAVE
 TROUGH OVER THE CENTRAL U.S. DIGS SOUTHEASTWARD TOWARD THE NORTHERN
 GULF OF MEXICO AND SOUTHEASTERN UNITED STATES. THE TIMING OF THE
 EROSION OF THE RIDGE AND AN INDUCED NORTHWARD MOTION OF KATRINA IS
 THE MAIN DIFFERENCE BETWEEN THE MODELS...WHICH HAS RESULTED IN A
 LARGE SPREAD AFTER 48 HOURS. THE NOGAPS AND GFDN MODELS HAVE MADE A
 LARGE JUMP TO THE WEST OVER LOUISIANA...WHEREAS THE MAJORITY OF THE
 NHC MODELS TAKE KATRINA INLAND OVER THE NORTHEAST GULF COAST. THE
 OFFICIAL FORECAST TRACK REMAINS IN THE RIGHT PORTION OF THE MODEL
 GUIDANCE ENVELOPE.
 
 STRENGTHENING TO A MAJOR HURRICANE IS EXPECTED. IN FACT...A RECENT
 DROPSONDE REPORT RECEIVED FROM THE RECONNAISSANCE AIRCRAFT
 INDICATES MAXIMUM WINDS ARE NOW UP TO 80 KT. SO...A SPECIAL
 ADVISORY WILL BE ISSUED SHORTLY TO UPDATE THE CURRENT AND FORECAST
 INTENSITIES.
  
 FORECASTER STEWART
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      26/1500Z 25.1N  82.2W    70 KT
  12HR VT     27/0000Z 25.2N  83.1W    75 KT
  24HR VT     27/1200Z 25.5N  84.3W    80 KT
  36HR VT     28/0000Z 26.2N  85.2W    85 KT
  48HR VT     28/1200Z 27.1N  85.9W    90 KT
  72HR VT     29/1200Z 29.5N  86.3W   100 KT
  96HR VT     30/1200Z 34.5N  83.5W    35 KT...INLAND
 120HR VT     31/1200Z 40.5N  77.0W    25 KT...DISSIPATING INLAND
  
  
 $$