Tropical Storm PHANFONE Advisory Thu Dec 26

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 30W (PHANFONE) WARNING NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 30W (PHANFONE), LOCATED APPROXIMATELY 584 NM EAST-
SOUTHEAST OF DA NANG, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD AT 07
KNOTS (KTS) OVER THE PAST SIX HOURS. A 10 NM, PARTIALLY CLOUD-FILLED EYE
IN ANIMATED MULTISPECTRAL SATELLITE IMAGERY PROVIDES HIGH CONFIDENCE IN
THE INITIAL POSITION. THE INITIAL INTENSITY FALLS BETWEEN DVORAK FIX
INTENSITIES OF T4.5 (77 KTS) AND T5.0 (90 KTS) FROM RJTD AND PGTW,
RESPECTIVELY. THE 34 AND 50 KT WIND RADII WERE ASSESSED USING A 260205Z
METOP-B ASCAT PASS. WITH FAIR POLEWARD OUTFLOW, LOW (5-10 KT) VERTICAL
WIND SHEAR (VWS), AND WARM (27-28 CELSIUS) SEA SURFACE TEMPERATURE, THE
ENVIRONMENT IS MARGINALLY SUPPORTIVE. NOTABLY, THERE IS MUCH DRIER AIR
JUST TO THE WEST OF THE SYSTEM, SUGGESTING THE EYE MAY BE SHORT LIVED.
TY 30W IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF A SUBTROPICAL RIDGE
(STR).
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 30W WILL CONTINUE ON A WEST-NORTHWESTWARD TRACK UNTIL TAU 72
WHEN IT DISSIPATES DUE TO DRY AIR ENTRAINMENT AND HIGH VWS. SPREAD IN
THE MODEL GUIDANCE IS QUITE LARGE, REACHING 270 NM BY TAU 72. THE JTWC
TRACK FORECAST IS HEDGED NORTH OF CONSENSUS, NEAR THE ECMWF AND JGSM
SOLUTIONS, WITH LOW CONFIDENCE.//
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