Tropical Storm CEMPAKA Advisory Fri Jul 23

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 10W (CEMPAKA)
WARNING NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 22.6N 108.3E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 165 NM NORTHEAST OF HANOI, VIETNAM
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 06 KTS
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A BROAD,
EXPOSED LOW-LEVEL CIRCULATION (LLC) WITH LIMITED DEEP CONVECTION
CONFINED TO THE SOUTHERN SEMICIRCLE OVER WATER. A 220613Z AMSR2
89GHZ MICROWAVE IMAGE AND RADAR IMAGERY INDICATES WEAK CONVECTIVE
STRUCTURE AND A BROAD, WEAKLY-DEFINED LLC. THE INITIAL POSITION IS
PLACED WITH LOW CONFIDENCE BASED ON MSI. THE INITIAL INTENSITY OF
25 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A SLP
OBSERVATION OF 998MB FROM NANNING WUXU INTERNATIONAL AIRPORT
(ZGNN), WHICH CORRESPONDS TO A TD STRENGTH SYSTEM. IN ADDITION TO
LAND INTERACTION, UPPER-LEVEL ANALYSIS INDICATES MARGINAL
CONDITIONS WITH WEAK EQUATORWARD OUTFLOW.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT BETWEEN
A WEAK SUBTROPICAL RIDGE TO THE NORTH AND EXTENSIVE WESTERLIES TO
THE SOUTH.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: NO CURRENT ESTIMATE
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 5-10 KTS
   SST: OVER LAND
   OUTFLOW: WEAK EQUATORWARD
   OTHER FACTORS: INTERACTION WITH LAND
ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TD 10W CONTINUES TO STRUGGLE OVERLAND WITH
WEAK OVERALL STRUCTURE AND IS EXPECTED TO TURN SOUTHWARD AND
REEMERGE OVER THE GULF OF TONKIN BY TAU 24. AFTER TAU 24, TD 10W
WILL TRACK EASTWARD UNDER THE STEERING INFLUENCE OF THE LOW-LEVEL
WESTERLIES TO THE SOUTH. MINIMAL REINTENSIFICATION TO 30 KNOTS IS
ANTICIPATED AFTER TAU 24 UNTIL THE SYSTEM TRACKS OVER HAINAN
ISLAND, WHICH WILL LEAD TO DISSIPATION BY TAU 72 OR EARLIER.
ENVIRONMENTAL CONDITIONS WILL REMAIN MARGINAL THROUGH TAU 72 WITH
MODERATE TO STRONG VERTICAL WIND SHEAR AND WEAK OUTFLOW. THERE IS A
DISTINCT POSSIBILITY THE SYSTEM MAY DISSIPATE EARLIER IN THE
FORECAST PERIOD.
MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE SUPPORTS THE JTWC
FORECAST TRACK WITH LOW CONFIDENCE BUT GENERALLY SUPPORTS THE TRACK
PHILOSOPHY. INTENSITY GUIDANCE IS IN POOR AGREEMENT, THEREFORE,
THERE IS LOW CONFIDENCE IN THE JTWC INTENSITY FORECAST.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   INTENSITY 0 - 72 HR: LOW//
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