Tropical Storm KALMAEGI Advisory 11.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (FIFTEEN)
WARNING NR 02//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 15W (FIFTEEN), LOCATED APPROXIMATELY 96 NM
EAST-NORTHEAST OF YAP, HAS TRACKED WESTWARD AT 16 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL IMAGERY (MSI) DEPICTS A
SLIGHTLY LESS CONSOLIDATED LOW-LEVEL CIRCULATION CENTER (LLCC) THAN
6 HOURS AGO, WITH BROAD CONVECTION VISIBLE ALONG THE WESTERN AND
SOUTHERN PERIPHERY. A 102111Z SSMIS IMAGE DEPICTS CONVECTIVE
ACTIVITY ALONG THE EXTREME WESTERN EDGE OF THE SYSTEM. INITIAL
POSITION IS BASED ON THE MSI LOOP WITH LOW CONFIDENCE AS THE MAIN
AREAS OF CONVECTION HAVE BEEN SHEARED TO THE WEST OF THE APPARENT
LLCC. UPPER LEVEL ANALYSIS INDICATES EQUATORWARD OUTFLOW AND
MODERATE (15 TO 20 KTS) NORTHEASTERLY VERTICAL WIND SHEAR (VWS).
INTENSITY IS MAINTAINED AT 25 KNOTS BASED ON CURRENT DVORAK
INTENSITY ESTIMATES FROM ALL AGENCIES. TD 15W IS CURRENTLY TRACKING
WESTWARD UNDER THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTHEAST OF THE SYSTEM.
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE
FORECAST PHILOSOPHY.
   B. THE STR TO THE NORTHEAST CONTINUES TO INFLUENCE THE WEST TO
WEST-NORTHWEST TRACK OF TD 15W THROUGH TAU 48. WHILE MODELS ARE IN
AGREEMENT THAT THE STR BREAKS DOWN, THERE IS SIGNIFICANT
DISAGREEMENT IN THE DEGREE OF THE WEAKNESS IN THE RIDGE. NAVGEM
DEPICTS THE STR BREAKING DOWN FASTER AND THE SYSTEM TURNING TO THE
NORTH INTO A SMALL BREAK IN THE RIDGE BEYOND TAU 48 AND THEN
CONTINUING TO THE NORTHWEST. GFS AND ECMWF SOLUTIONS HAVE TD 15W
SLOWING SLIGHTLY BY TAU 48 AND 72 DUE TO THE SMALL BREAK IN THE
RIDGE AND THE WEAKENING STEERING ENVIRONMENT, BEFORE CONTINUING
WESTWARD UNDER THE RE-BUILDING STR. THE INTENSITY OF THE SYSTEM IS
EXPECTED TO INCREASE AT A STEADY RATE THROUGH TAU 72, WITH GOOD
MODEL AGREEMENT, DUE TO HIGH SEA SURFACE TEMPERATURES AND A
FAVORABLE UPPER-LEVEL ENVIRONMENT.
   C. BEYOND TAU 72, MODELS CONTINUE TO DIVERGE, WITH THE GFS AND
ECMWF SOLUTIONS TAKING THE SYSTEM THROUGH NORTH CENTRAL LUZON AND
THE NAVGEM MODEL FAVORING A TRACK TOWARDS SOUTHERN TAIWAN. AS SUCH,
THE FORECAST TRACK IN THE LATER TAUS ALIGNS CLOSELY WITH THE
CONSENSUS OF MODEL GUIDANCE, TRACKING INTO NORTHERN LUZON AFTER BY
TAU 96. LAND INTERACTION DURING THIS TIMEFRAME WILL IMPEDE FURTHER
INTENSIFICATION DESPITE FORECASTED GOOD EQUATOR OUTFLOW AND AVERAGE
VWS. THE OVERALL CONFIDENCE IN JTWC TRACK IS LOW DUE TO DISPARITIES
DEPICTED IN THE DIFFERENT MODELS’ STEERING ENVIRONMENTS AFTER TAU
48.//
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