Tropical Storm PHANFONE Advisory Sun Dec 22

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 30W (PHANFONE) WARNING NR
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 30W (PHANFONE), LOCATED APPROXIMATELY 96 NM SOUTH
OF YAP, HAS TRACKED NORTHWESTWARD AT 14 KNOTS (KTS) OVER THE PAST SIX
HOURS. THERE IS FAIR CONFIDENCE IN THE INITIAL POSITION BASED OFF
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) WHICH SHOWS SUSTAINED
DEEP CONVECTION TO THE NORTHWEST OF A PARTIALLY EXPOSED LOW LEVEL
CIRCULATION (LLC). THE 35 KT INITIAL INTENSITY IS BASED ON AN AVERAGE OF
PGTW/RJTD DVORAK ESTIMATES OF T2.0-T2.5 (30-35 KTS) AND A 220406Z CIMSS
SATCON ESTIMATE OF 40 KTS. THE ENVIRONMENT IS VERY FAVORABLE WITH LOW
(10-15 KT) VERTICAL WIND SHEAR, GOOD POLEWARD AND EQUATORWARD OUTFLOW
CHANNELS, AND WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURE. TS 30W IS
TRACKING ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC
REASONING MESSAGE.
   B. TS 30W WILL FOLLOW A WEST-NORTHWESTWARD TO NORTHWESTWARD TRACK FOR
THE DURATION OF THE FORECAST. THE FAVORABLE ENVIRONMENT WILL SUPPORT
STEADY, POSSIBLY RAPID, INTENSIFICATION PRIOR TO LANDFALL IN THE CENTRAL
PHILIPPINES SHORTLY AFTER TAU 48. LAND INTERACTION WILL INHIBIT FURTHER
INTENSIFICATION THROUGH TAU 72. WITH THE EXCEPTION OF NAVGEM, WHICH IS A
SLIGHT NORTHERN OUTLIER, NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT,
LENDING TO GOOD CONFIDENCE THROUGH TAU 72.
   C. AFTER TAU 72, TS 30W WILL EMERGE OVER THE SOUTH CHINA SEA AND
CONTINUE TO TRACK WEST-NORTHWESTWARD. ONCE OVER WATER, SLIGHT
INTENSIFICATION IS EXPECTED UNTIL HIGH VWS AND INTERACTION WITH
RELATIVELY COOL, DRY AIR CAUSES WEAKENING BY TAU 120. WITH THE EXCEPTION
OF NAVGEM, NUMERICAL MODEL GUIDANCE REMAINS IN FAIR AGREEMENT IN THE
EXTENDED PERIOD. THE JTWC TRACK FORECAST IS HEDGED JUST SOUTH OF
CONSENSUS TO OFFSET THE INFLUENCE OF NAVGEM, WITH FAIR CONFIDENCE.//
NNNN
NNNN