Tropical Storm ONE Advisory vie, 24-07

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 01C (HALOLA) WARNING NR 58//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 01C (HALOLA), LOCATED APPROXIMATELY 195 NM EAST-
SOUTHEAST OF KADENA AB, HAS TRACKED WESTWARD AT 07 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY
CONTINUES TO SHOW A WEAKENING CONVECTIVE SIGNATURE WITH SIGNIFICANT
DRY AIR DISSIPATING CONVECTION ALONG THE NORTHERN PERIPHERY OF THE
CYCLONE'S CORE. TY 01C MAINTAINS GOOD SPIRAL BANDING ALONG THE
SOUTHERN AND EASTERN QUADRANTS WRAPPING INTO THE CENTER. WATER VAPOR
IMAGERY DEPICTS DRY AIR ALONG THE NORTHERN AND EASTERN PERIPHERIES
WITH A STRONG EQUATORWARD OUTFLOW CHANNEL. A 240959Z SSMIS 91GHZ
SHOWS A WELL-DEFINED LOW LEVEL CIRCULATION CENTER WITH NO
SIGNIFICANT CONVECTION WITHIN THE NORTHERN CORE AND DRY AIR
COMPLETELY SURROUNDING THE CIRCULATION. THE STRONGEST CONVECTION
EXTENDS 60NM TO THE SOUTH-SOUTHEAST OF THE CENTER. A 241211Z
SCATTEROMETER BULLSEYE SHOWS AN EAST TO WEST ELONGATED LLCC WITH THE
DEEPEST WIND FIELD ALONG THE NORTHEASTERN PERIPHERY. THE UPPER LEVEL
ENVIRONMENT CONTINUES TO DETERIORATE DUE TO DRY AIR ENTRAINMENT AND
MODERATE VERTICAL WIND SHEAR (VWS). THE INITIAL POSITION IS BASED ON
THE ASCAT PASS AND IS SUPPORTED BY SATELLITE FIXES FROM PGTW AND
RJTD AS WELL AS RADAR FIXES FROM RJTD. THE INITIAL INTENSITY HAS
BEEN LOWERED TO 70 KNOTS DUE TO DECREASING DVORAK INTENSITY
ESTIMATES AND SUPPORTS THE WEAKENING SIGNATURE SEEN IN ALL IMAGERY.
TY 01C CONTINUES TO TRACK ALONG THE SOUTHERN PERIPHERY OF THE DEEP-
LAYERED SUB-TROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE. THE WIND RADII HAVE BEEN ADJUSTED
BASED ON THE AFOREMENTIONED ASCAT PASS.
   B. TY HALOLA WILL CONTINUE TRACKING WESTWARD TO WEST-
NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR OVER THE NEXT
12 HOURS. BEYOND TAU 12, TY HALOLA WILL REACH THE WESTERN EXTENT OF
THE STEERING STR AND BEGIN TO ROUND THE SOUTHWESTERN PERIPHERY.
AFTERWARDS, TY 01C WILL TURN NORTHEASTWARD AND START TO ACCELERATE
ALONG THE NORTHWESTERN PERIPHERY OF THE STR. DYNAMIC MODEL GUIDANCE
HAS COME INTO BETTER AGREEMENT AS THE TYPHOON'S CENTER PASSES
THROUGH THE RYUKYU ISLANDS WITH A 60NM SPREAD. THE JTWC TRACK IS
POSITIONED AT THE WESTERN EDGE OF THE GUIDANCE DUE TO THE FORECASTED
CONTINUED WEAKENING. TY 01C WILL FURTHER WEAKEN THROUGH TAU 48 DUE
TO THE MARGINAL ENVIRONMENTAL CONDITIONS. BEYOND TAU 48, TY HALOLA
WILL ACCELERATE NORTHEASTWARD WITHIN THE MIDLATITUDE WESTERLY FLOW.
TY 01C WILL RAPIDLY WEAKEN DUE TO STRONG VWS, COLD SSTS (23C TO 22C)
AND CONTINUED LAND INTERACTION. TY 01C IS FORECAST TO FULLY
DISSIPATE BY THE END OF THE FORECAST PERIOD. THERE IS NO BAROCLINIC
SUPPORT FOR EXTRA-TROPICAL TRANSITION AT THIS TIME. THERE IS STILL
SOME UNCERTAINTY AS TY HALOLA ROUNDS THE STR; HOWEVER, MODEL
GUIDANCE IS NOW WITHIN 80NM AT TAU 48 AND BETTER AGREEMENT BEYOND.
ALTHOUGH THERE IS HIGHER CONFIDENCE WITH THE IMPROVED MODEL
GROUPING, THERE REMAINS LOW OVERALL CONFIDENCE IN THE TIMING OF THE
RE-CURVE AND, THEREFORE, IN THE OVERALL TRACK FORECAST.//
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