Tropical Storm SARIKA Advisory czw., 13.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 24W (TWENTY-FOUR)
WARNING NR 03//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 24W (TWENTY-FOUR), LOCATED APPROXIMATELY 520
NM EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-
NORTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL (MSI) SATELLITE IMAGERY SHOWS DISORGANIZED CONVECTIVE
BANDING SLOWLY CONSOLIDATING AROUND AN OBSCURED AND ILL-DEFINED LOW
LEVEL CIRCULATION CENTER (LLCC). DESPITE THE STILL SOMEWHAT
DISORGANIZED CONVECTIVE SIGNATURE, A 122232Z SSMIS 91 GHZ MICROWAVE
IMAGERY PASS INDICATES THE POSSIBLE MULTIPLE LLCCS FROM THE
PREVIOUS DISCUSSION ARE CONSOLIDATING INTO A SINGLE, MORE SYMMETRIC
LLCC UNDER THE DENSE OVERCAST. THE INITIAL POSITION IS BASED ON THE
CENTROID OF THE BROAD BANDING FEATURES IN THE AFOREMENTIONED MSI AND
MICROWAVE IMAGES WITH FAIR CONFIDENCE. THE INITIAL INTENSITY REMAINS
AT 30 KNOTS BASED ON THE PGTW DVORAK ESTIMATE OF T2.0 (30 KNOTS).
THE SYSTEM RESIDES IN A FAVORABLE ENVIRONMENT, WITH LOW VERTICAL
WIND SHEAR, DUAL OUTFLOW CHANNELS, AND VERY WARM SEA SURFACE
TEMPERATURES WITH HIGH OCEAN HEAT CONTENT (OHC). A TROPICAL UPPER
TROPOSPHERIC TROUGH (TUTT) CELL CURRENTLY LOCATED TO THE NORTHWEST
IS SLIGHTLY ENHANCING POLEWARD OUTFLOW AT THIS TIME, BUT WILL MOVE
OUT OF THE AREA OVER THE NEXT 12 HOURS. THE CYCLONE IS TRACKING
ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR)
TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TD 24W IS EXPECTED TO TRACK SLOWLY WEST-NORTHWESTWARD ALONG
THE SOUTHERN PERIPHERY OF THE STR THROUGHOUT THE FORECAST PERIOD. AS
THE INITIAL POSITION HAS BECOME MORE SOLID, THE TRACK UNCERTAINTY IN
THE PREVIOUS FORECAST HAS DECREASED. THROUGH TAU 24, INTENSIFICATION
SHOULD OCCUR AT NEAR CLIMATOLOGICAL RATE AS THE LLCC CONTINUES TO
ORGANIZE AND THE AFOREMENTIONED TUTT CELL MOVES OUT OF THE AREA.
BETWEEN TAUS 24 AND 48, TD 24W IS FORECAST TO SLOW ITS FORWARD
MOTION IN RESPONSE TO DEVELOPMENT OF A WEAKNESS IN THE STR FAR TO
THE NORTH OVER TAIWAN, IN CONJUNCTION WITH DEVELOPMENT OF A NEAR-
EQUATORIAL RIDGE (NER) TO THE SOUTH RESULTING IN A WEAK STEERING
ENVIRONMENT. THE STR REESTABLISHES TO THE NORTH AFTER TAU 48 AND TD
24W WILL ACCELERATE TOWARDS LUZON. BY TAU 48, ANOTHER TUTT
DEVELOPING TO THE NORTHEAST OF TD 24W WILL MOVE WESTWARD INTO A
FAVORABLE POSITION TO PROVIDE INCREASED OUTFLOW, WHICH COMBINED WITH
THE VERY FAVORABLE CONDITIONS NOTED, WILL PROVIDE AN ELEVATED
POTENTIAL FOR RAPID INTENSIFICATION AFTER TAU 48. FORECAST
INTENSITIES PRIOR TO LANDFALL HAVE BEEN ADJUSTED UPWARDS SLIGHTLY TO
A PEAK OF 100 KNOTS AT TAU 72 AS A RESULT. HOWEVER, THE ACTUAL PEAK
MAY OCCUR AFTER TAU 72, PRIOR TO LANDFALL.
   C. IN THE EXTENDED TAUS, TD 24W WILL MOVE ACROSS LUZON AND WEAKEN
SLIGHTLY DUE TO LAND INTERACTION, BEFORE EXITING INTO THE SOUTH
CHINA SEA (SCS). RE-INTENSIFICATION IS EXPECTED IN THE SCS AS
GENERALLY FAVORABLE CONDITIONS WILL CONTINUE. NUMERICAL MODEL
GUIDANCE BECOMES INCREASINGLY DIVERGENT AFTER TAU 72, WITH SOME
MODELS INDICATING A DEVELOPING WEAKNESS IN THE STR CAUSING A MORE
NORTHERLY TRACK, WHILE THE MAJORITY OF THE GUIDANCE MAINTAINS THE
STR. THE FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL CONSENSUS.
DUE TO THE VARIABILITY IN THE INITIAL POSITIONING AND THE INCREASING
MODEL SPREAD AFTER TAU 72, THERE IS LOW CONFIDENCE IN THE JTWC TRACK
FORECAST.//
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