Tropical Storm PHANFONE Advisory lun, 29.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (EIGHTEEN) WARNING
NR 02//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 18W (EIGHTEEN), LOCATED APPROXIMATELY 301 NM NORTH
OF CHUUK, HAS TRACKED WESTWARD AT 11 KNOTS OVER THE PAST SIX
HOURS. ANIMATED MULTISPECTRAL IMAGERY (MSI) CONTINUES TO DEPICT
BROAD CIRCULATION ABOUT A POORLY DEFINED LOW-LEVEL CIRCULATION
CENTER (LLCC). A 28216Z SSMIS IMAGE REVEALS FORMATIVE BANDING ALONG
THE NORTHERN PERIPHERY OF THE SYSTEM AND DEEP CONVECTION TO THE
SOUTHEAST. HOWEVER THERE IS LOW CONFIDENCE IN ITS INITIAL POSITION
DUE TO THE CHAOTIC NATURE OF THE SYSTEMS STRUCTURE. THE INITIAL
INTENSITY IS ASSESSED AT 35 KNOTS BASED ON THE DVORAK CURRENT
INTENSITY ESTIMATES FROM PGTW AND KNES. THERE IS A FAVORABLE UPPER-
LEVEL ENVIRONMENT DUE TO LOW (5 TO 10 KNOTS) OF VERTICAL WIND SHEAR
(VWS) AND RADIAL OUTFLOW, WITH THE POSSIBILITY OF A POINT SOURCE TO
THE NORTHWEST. TS 18W IS TRACKING TO THE WEST ALONG THE SOUTHERN
PERIPHERY OF THE SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 18W WILL CONTINUE TO TRACK ALONG THE SOUTHWESTERN EDGE OF
THE STR THROUGH THE NEXT 72 HOURS, TAKING A MORE NORTHWESTWARD
ROUTE. LIMITED MODEL GUIDANCE IS IN OVERALL GOOD AGREEMENT WITH THE
SYSTEM TRACKING TO THE NORTHWEST OVER THE NEXT 48 HOURS.
ADDITIONALLY, EXPECT THE UPPER-LEVEL ENVIRONMENT TO IMPROVE AND HIGH
SEA SURFACE TEMPERATURES ALONG THE TRACK TO POSSIBLY PRODUCE A RAPID
INTENSIFICATION SCENARIO WITHIN THE NEXT 72 HOURS. IT SHOULD BE
NOTED THAT THE SPREAD IN THE MODELS BECOME MORE SIGNIFICANT NEAR TAU
72, WITH A DISPARITY OF ABOUT 200NM.
   C. IN THE EXTENDED FORECAST, THERE IS MODERATE DISAGREEMENT IN
MODELS WITH REGARD TO THE STRENGTH OF THE STR AND WHERE TS 18W
BEGINS TO TURN INTO THE BREAK IN THE RIDGE. HWRF CONTINUES TO BE THE
WESTERN, MORE FLAT OUTLIER WHILE COAMPS-TC DEPICTS THE EASTERN, MORE
NORTHERN SCENARIO. DUE TO THE SPREAD OF OVER 450NM IN BY TAU 120,
THE JTWC TRACK CLOSELY RESEMBLES THE MULTI-MODEL CONSENSUS WITH
OVERALL LOW CONFIDENCE IN THE FORECAST TRACK.//
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