Tropical Storm SAOLA Advisory сб, 28.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 27W (SAOLA) WARNING NR
33//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 27W (SAOLA), LOCATED APPROXIMATELY 151 NM SOUTH
OF KADENA, AB, OKINAWA, JAPAN, HAS TRACKED NORTHWARD AT 08 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY SHOWS THE SYSTEM HAS MOSTLY MAINTAINED DEEP CONVECTIVE BANDS
FEEDING INTO A BROAD AND RAGGED LOW LEVEL CIRCULATION. ADDITIONALLY,
THE EIR LOOP INDICATES NORTHERLY LOW LEVEL DRY AIR ENTRAINMENT ALONG
THE WESTERN SEMI-CIRCLE. THE INITIAL POSITION IS BASED ON A WARM
NOTCH FEATURE IN THE EIR LOOP THAT LINES UP WITH A WELL-DEFINED
CIRCULATION FEATURE IN THE 271304Z ASCAT BULLSEYE PASS. THE ASCAT
IMAGE WAS ALSO USED TO ADJUST THE TAU 00 34-KNOT WIND RADIUS. THE
INITIAL INTENSITY OF 55 KNOTS IS BASED ON THE PGTW DVORAK ESTIMATE OF
T3.5 AND REFLECTS THE SUSTAINED CONVECTIVE SIGNATURE OF TS 27W.
UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF LOW TO
MODERATE (10-15 KNOT) VERTICAL WIND SHEAR (VWS) AND STRONG POLEWARD
AND EQUATORWARD OUTFLOW. HOWEVER, THERE IS STRONG SUBSIDENCE ALONG
THE WESTERN SEMI-CIRCLE CAUSED BY THE LEADING EDGE OF A MID-LATITUDE
TROUGH DIGGING IN FROM CHINA. SSTS REMAIN RELATIVELY WARM NEAR 28
CELSIUS. THE CYCLONE IS TRACKING ALONG THE WESTERN BOUNDARY OF A
DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS SAOLA WILL CONTINUE TRACKING NORTHWARD AS IT ROUNDS THE
WESTERN EDGE OF THE STR OVER THE NEXT 24 HOURS, PASSING DIRECTLY OVER
OKINAWA. AFTERWARD, IT WILL RECURVE AND ACCELERATE NORTHEASTWARD AS
IT GETS EMBEDDED IN THE MID-LATITUDE WESTERLIES AND SKIRTS THE
SOUTHERN COAST OF MAINLAND JAPAN. THE INITIAL EXPOSURE INTO THE
STRONG WESTERLIES WILL ENHANCE POLEWARD OUTFLOW AND INTENSIFY 27W TO
A PEAK OF 65 KNOTS BETWEEN TAU 12-24. AFTER TAU 24, THE STRONG WINDS
WILL TRANSLATE TO STRONG VWS; ADDITIONALLY, COOL DRY AIR ADVECTION
AND COOLING SSTS, CONCURRENT WITH EXTRA-TROPICAL TRANSITION (ETT) BY
TAU 36, WILL STEADILY ERODE THE SYSTEM. BY TAU 48, THE SYSTEM WILL
BECOME A STORM-FORCE COLD CORE LOW WITH A RAPIDLY EXPANDING WIND
FIELD. BY TAU 72, SAOLA, WILL BE DEEPLY ABSORBED IN THE BAROCLINIC
ZONE SOUTH OF KAMCHATKA. THE DYNAMIC MODEL GUIDANCE IS IN OVERALL
GOOD AGREEMENT WITH THE FORECAST TRACK. HOWEVER, AS TYPICAL WITH
RECURVE SCENARIOS, THERE IS SIGNIFICANT DIFFERENCES IN THE LATERAL
SPEED AMONG THE TRACK MEMBERS. THE TRACK SPEEDS DIFFER EVEN GREATER
AT THE ETT PHASE. IN VIEW OF THIS, THERE IS FAIR CONFIDENCE IN THE
JTWC TRACK FORECAST UP TO TAU 36, THEN LOW CONFIDENCE AFTERWARD.//
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