Tropical Storm EMILIA

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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
 
$$
FORECASTER BEVEN
 
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