285 
 WTPA44 PHFO 040905
 TCDCP4
 
 TROPICAL STORM GUILLERMO DISCUSSION NUMBER  22
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP092015
 1100 PM HST MON AUG 03 2015
  
 THE LATEST INFRARED SATELLITE PRESENTATION OF GUILLERMO HAS 
 IMPROVED SINCE THE LAST ADVISORY...WITH PERSISTENT DEEP CONVECTION 
 REMAINING NEAR AND TO THE NORTHEAST OF THE LOW LEVEL CIRCULATION 
 CENTER. IT REMAINS EVIDENT THAT GUILLERMO IS UNDERGOING QUITE A BIT 
 OF WESTERLY WIND SHEAR WITH THE DEEP CONVECTION TILTING THE SYSTEM 
 OFF TO THE NORTHEAST...AND THIS IS SHOWN WELL BY THE LATEST 
 UW-CIMSS VERTICAL WIND SHEAR ANALYSIS INDICATING 20 KNOTS OF SHEAR 
 FROM 265 DEGREES. DESPITE THE VERTICAL WIND SHEAR PRESENT OVER THE 
 SYSTEM...DVORAK CLASSIFICATIONS FROM PHFO...SAB...AND JTWC CONTINUE 
 TO INDICATE T NUMBERS OF 3.5 OR 55 KNOTS. THE FINAL DECISION ON THE 
 INITIAL INTENSITY WAS BASED HEAVILY ON TIMELY DATA FROM THE U.S. 
 53RD WEATHER RECONNAISSANCE AIRCRAFT WHICH IS CURRENTLY SAMPLING
 THE INNER CORE OF GUILLERMO. THE AIRCRAFT FOUND MAX FLIGHT LEVEL
 WINDS OF 72 KNOTS...33 NM NORTHEAST OF THE CENTER OF CIRCULATION.
 ADJUSTING THE FLIGHT LEVEL WINDS TO THE SURFACE YIELDS SURFACE WINDS
 OF 58 MPH. ADDITIONALLY...SFMR DATA FROM THE AIRCRAFT INDICATED
 SURFACE WINDS AS STRONG AS 68 KNOTS TO THE NORTHEAST OF THE CENTER.
 SOME OF THE SFMR WINDS MAY HAVE BEEN RAINFALL CONTAMINATED...AND AS
 A RESULT...THE INITIAL INTENSITY OF GUILLERMO UTILIZED A BLEND OF
 THE FLIGHT LEVEL AND SFMR WINDS AND WAS SET AT 60 KNOTS...JUST BELOW
 HURRICANE STRENGTH. 
 
 THE INITIAL POSITION OF THE SYSTEM WAS BASED ON CENTER FIX
 POSITIONS FROM THE RECONNAISSANCE AIRCRAFT AS WELL...WITH AN INITIAL
 MOTION TOWARD THE NORTHWEST OR 325 DEGREES AT 10 KNOTS. THE LATEST
 MODEL GUIDANCE SHOWS THE TRACK SHIFTING BACK SLIGHTLY TOWARD THE
 LEFT OR CLOSER TO THE HAWAIIAN ISLANDS...BUT THESE MODELS APPEAR TO
 BE STRUGGLING WITH THE CURRENT MOTION. THE SYSTEMS MOTION APPEARS
 TO BE DRIVEN LARGELY BY A WEAKNESS IN THE MID-UPPER LEVEL RIDGE
 WHICH EXTENDS FROM GUILLERMO OFF TO THE NORTHWEST TO A LOCATION
 NEAR 30N157W. THIS WEAKNESS IN THE RIDGE IS DRIVING THE MOTION OF 
 GUILLERMO AT THE CURRENT TIME DUE TO THE DEEP CONVECTION IN PLACE 
 NEAR AND TO THE NORTHEAST OF THE CIRCULATION CENTER. AS A 
 RESULT...THE OFFICIAL FORECAST FOLLOWS A DIRECTION ON THE NORTH
 SIDE OF THE GUIDANCE ENVELOPE THROUGH 24 HOURS WHICH ASSUMES
 MAINTENANCE OF DEEP CONVECTION AND INTERACTION WITH THE WEAKNESS IN
 THE MID-UPPER LEVEL RIDGE. BEYOND 24 HOURS AS WESTERLY WIND SHEAR
 IS FORECAST TO INCREASE SIGNIFICANTLY OVER THE SYSTEM...A SHIFT
 TOWARD THE WEST-NORTHWEST IS EXPECTED...WHICH IS VERY CLOSE TO THE
 PREVIOUS OFFICIAL FORECAST TRACK. ON THIS TRACK...THE CLOSEST
 APPROACH OF GUILLERMO REMAINS WELL TO THE NORTHEAST OF ALL THE
 HAWAIIAN ISLANDS...SO THE WATCH WAS MAINTAINED WITH THIS ADVISORY
 PACKAGE. IF THE TRACK SHIFTS BACK CLOSER TO THE ISLANDS LATER
 TONIGHT OR TUESDAY...A TROPICAL STORM WARNING MAY BE NEEDED FOR THE
 BIG ISLAND OR MAUI COUNTY...BUT THIS IS NOT ANTICIPATED AT THIS
 TIME.
 
 THE INTENSITY FORECAST FOR GUILLERMO IS A BLEND OF ICON AND HWRF 
 INTENSITY GUIDANCE ALONG WITH WEIGHT GIVEN TO THE PREVIOUS OFFICIAL 
 FORECAST. THE GLOBAL MODELS ARE SHOWING THE POTENTIAL FOR
 DECREASING VERTICAL WIND SHEAR LATER TONIGHT WITH A WINDOW OF
 OPPORTUNITY FOR STRENGTHENING POSSIBLE THROUGH WEDNESDAY 05/18Z.
 AFTER 05/18Z...VERTICAL WIND SHEAR IS FORECAST TO STRENGTHEN TO 25
 KNOTS OR GREATER OVER THE SYSTEM...AND THIS SHOULD LEAD TO STEADY 
 WEAKENING OF THE SYSTEM THEREAFTER. GIVEN THE POTENTIAL FOR 
 WEAKENING OF THE SHEAR ALONG WITH FAVORABLE SEA SURFACE
 TEMPERATURES OF AROUND 82 DEGREES FAHRENHEIT BASED ON MODIS DATA
 FROM EARLIER THIS AFTERNOON...IT IS NOT OUT OF THE QUESTION THAT
 GUILLERMO COULD BECOME A HURRICANE OVER THE NEXT 12 HOURS. THE
 OFFICIAL INTENSITY FORECAST WILL SHOW LITTLE CHANGE IN STRENGTH
 HOWEVER OVER THE NEXT 12 HOURS...THEN SHOW SLOW BUT STEADY WEAKENING
 THROUGH 120 HOURS. 
 
 ANOTHER RECONNAISSANCE AIRCRAFT MISSION INTO GUILLERMO IS SCHEDULED 
 FOR 12Z TUESDAY MORNING. THE VALUABLE DATA TRANSMITTED IN REAL-TIME 
 FROM THESE MISSIONS WILL HELP US TO BETTER DETERMINE THE
 LOCATION...INTENSITY AND SIZE OF THE TROPICAL STORM...ALONG WITH
 ANY POTENTIAL IMPACTS TO THE HAWAIIAN ISLANDS.
  
  
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  04/0900Z 18.9N 147.7W   60 KT  70 MPH
  12H  04/1800Z 19.7N 148.9W   60 KT  70 MPH
  24H  05/0600Z 20.5N 150.7W   50 KT  60 MPH
  36H  05/1800Z 21.3N 152.6W   45 KT  50 MPH
  48H  06/0600Z 22.2N 154.5W   40 KT  45 MPH
  72H  07/0600Z 24.2N 158.5W   35 KT  40 MPH
  96H  08/0600Z 26.0N 163.0W   30 KT  35 MPH
 120H  09/0600Z 27.0N 167.5W   25 KT  30 MPH
  
 $$
 FORECASTER JELSEMA/BIRCHARD