206 
 WTPZ41 KNHC 222034
 TCDEP1
 TROPICAL STORM HILDA DISCUSSION NUMBER   2
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP112009
 200 PM PDT SAT AUG 22 2009
  
 VISIBLE SATELLITE PICTURES INDICATE THAT THE CENTER OF THE HILDA
 LIES NEAR THE NORTHEASTERN EDGE OF A MASS OF DEEP CONVECTION.
 HOWEVER...THE CONVECTION HAS BEEN DECREASING IN STRENGTH AND
 COVERAGE OVER THE LAST FEW HOURS AS THE DIURNAL MINIMUM APPROACHES.
 EARLIER...A 1534 UTC QUIKSCAT PASS SHOWED A COUPLE OF BELIEVABLE
 30-35 KT WINDS IMMEDIATELY TO THE NORTHEAST OF THE CIRCULATION
 CENTER...SUGGESTING THAT THE SYSTEM WAS NEAR TROPICAL STORM
 STRENGTH AT THAT TIME. DVORAK T-NUMBERS FROM TAFB AND SAB WERE 2.5
 AT 1800 UTC...AND SERVE AS THE BASIS FOR THE INITIAL
 INTENSITY...WHICH IS SET AT 35 KT.
 
 THE INITIAL MOTION IS ESTIMATED TO BE 275/09. THE LARGE-SCALE MODELS
 SHOW THAT THE CYCLONE LIES TO THE SOUTH OF THE EASTERN EDGE OF A
 SUBTROPICAL RIDGE OVER THE CENTRAL NORTH PACIFIC...WHICH SHOULD
 STEER HILDA ON A GENERAL WESTERLY COURSE FOR THE NEXT FEW DAYS.
 AROUND 72 HOURS...A DEEP MID- TO UPPER-LEVEL TROUGH IS FORECAST TO
 DIG SOUTHWARD ALONG 135W...WHICH SHOULD TEMPORARILY WEAKEN
 SUBTROPICAL RIDGING NORTH OF HILDA. AS A RESULT...THE FORWARD SPEED
 OF THE CYCLONE SHOULD BEGIN TO SLOW IN A WEAKER DEEP-LAYER EASTERLY
 FLOW. THE OFFICIAL FORECAST IS SLIGHTLY SOUTH OF THE PREVIOUS
 ADVISORY TO ACCOUNT FOR THE MORE WESTERLY INITIAL MOTION.
 
 HILDA REMAINS IN AN ENVIRONMENT CHARACTERIZED BY MODERATE
 NORTHEASTERLY SHEAR...AND LITTLE CHANGE IN THE SHEAR IS EXPECTED
 THROUGH AT LEAST 72 HOURS. EVEN THOUGH WATERS REMAIN SUFFICIENTLY
 WARM ALONG THE FORECAST TRACK...IT APPEARS THAT THE SHEAR SHOULD BE
 ENOUGH TO PRECLUDE ANY SIGNIFICANT INTENSIFICATION. TOWARD THE END
 OF THE PERIOD...SOME OF THE GUIDANCE SUGGESTS THAT THE SHEAR COULD
 DECREASE...WHICH COULD ALLOW FOR SOME STRENGTHENING. THE OFFICIAL
 FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY...AND IS CLOSE TO THE
 MODEL INTENSITY CONSENSUS.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      22/2100Z 13.6N 137.7W    35 KT
  12HR VT     23/0600Z 13.8N 139.0W    35 KT
  24HR VT     23/1800Z 14.1N 140.7W    35 KT
  36HR VT     24/0600Z 14.5N 142.3W    35 KT
  48HR VT     24/1800Z 14.9N 144.0W    40 KT
  72HR VT     25/1800Z 15.0N 147.5W    40 KT
  96HR VT     26/1800Z 15.0N 150.5W    45 KT
 120HR VT     27/1800Z 15.0N 153.0W    55 KT
  
 $$
 FORECASTER KIMBERLAIN/BRENNAN