648 
 WTPZ41 KNHC 220832
 TCDEP1
 TROPICAL STORM EMILIA DISCUSSION NUMBER   4
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP062006
 200 AM PDT SAT JUL 22 2006
 
 INFRARED SATELLITE IMAGERY SHOWS THAT A LARGE BURST OF CONVECTION
 HAS DEVELOPED NEAR OR JUST WEST OF THE LOW-LEVEL CENTER...WITH
 CLOUD TOPS NEAR -85C.  WHILE A SSM/I OVERPASS AT 0232Z SHOWS THAT
 THE CYCLONE IS STILL SHEARED...SATELLITE INTENSITY ESTIMATES ARE
 NOW 45 KT FROM TAFB AND SAB...AND 30 KT FROM AFWA.  BASED ON
 THIS...TROPICAL DEPRESSION SIX-E IS UPGRADED TO TROPICAL STORM
 EMILIA WITH 35-KT WINDS.
 
 THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 330/6.  LARGE-SCALE MODEL
 ANALYSES AND WATER VAPOR IMAGERY INDICATE THAT EMILIA IS ON THE
 SOUTHEAST SIDE OF A MID/UPPER-LEVEL RIDGE CENTERED OVER
 NORTHWESTERN MEXICO.  DUE TO THIS...MOST OF THE TRACK GUIDANCE
 CALLS FOR A GENERALLY NORTHWESTWARD OR WEST-NORTHWESTWARD MOTION
 THROUGH THE FORECAST PERIOD.  ONE EXCEPTION TO THIS IS THE
 GFS...WHICH TURNS EMILIA MORE WESTWARD AND IS THE LEFT OUTLIER OF
 THE TRACK FORECAST MODELS.  THE NEW FORECAST TRACK FOLLOWS THE
 CONSENSUS OF THE OTHER GUIDANCE...CALLING FOR A GENERALLY
 NORTHWESTWARD MOTION FOR THE NEXT 5 DAYS AND IS AN UPDATE OF THE
 PREVIOUS TRACK.  HOWEVER...GIVEN THE STRENGTH OF THE RIDGE THE GFS
 SOLUTION CANNOT BE RULED OUT.
  
 ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN SHOW THAT EMILIA
 IS UNDER 20-25 KT OF EASTERLY VERTICAL WIND SHEAR.  THIS SHOULD AT
 LEAST SLOW INTENSIFICATION IN THE SHORT-TERM.  THE LARGE-SCALE
 MODELS FORECAST THE SHEAR TO GRADUALLY DECREASE DURING THE NEXT 3
 DAYS...WHICH IF CORRECT SHOULD ALLOW GRADUAL STRENGTHENING.  THE
 GFDL MODEL CALLS FOR EMILIA TO PEAK AT 50 KT IN 48 HR...WHILE THE
 SHIPS MODEL CALLS FOR IT TO BECOME A HURRICANE IN ABOUT 72 HR.  THE
 INTENSITY FORECAST CALLS FOR SLOW INTENSIFICATION TO JUST UNDER
 HURRICANE STRENGTH BY 72 HR...FOLLOWED BY WEAKENING OVER COOLER SEA
 SURFACE TEMPERATURES BY 120 HR.  THE NEW INTENSITY FORECAST IS A
 LITTLE STRONGER THAN THE PREVIOUS PACKAGE.
 
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      22/0900Z 13.8N 104.0W    35 KT
  12HR VT     22/1800Z 14.6N 104.9W    40 KT
  24HR VT     23/0600Z 15.8N 106.4W    45 KT
  36HR VT     23/1800Z 16.8N 108.0W    50 KT
  48HR VT     24/0600Z 17.7N 109.4W    55 KT
  72HR VT     25/0600Z 19.5N 112.0W    60 KT
  96HR VT     26/0600Z 21.0N 114.5W    60 KT
 120HR VT     27/0600Z 23.0N 117.0W    50 KT
  
 $$