Tropical Storm SAOLA Advisory Sa, 24.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 27W (TWENTYSEVEN)
WARNING NR 17//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 27W (TWENTYSEVEN), LOCATED APPROXIMATELY 234 NM
SOUTH OF ANDERSEN AFB, GUAM, HAS TRACKED WESTWARD AT 11 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
SHOWS THE SYSTEM CONTINUED TO STRUGGLE AS THE BROAD AREA OF DEEP BUT
DISORGANIZED CONVECTION FED LOOSELY INTO AN ILL-DEFINED AND OBSCURED
LOW LEVEL CIRCULATION. THE INITIAL POSITION IS EXTRAPOLATED FROM LOW
REFLECTIVITY PERIPHERAL CIRCULATION OUTLINES IN THE 231652Z SSMI 37
GHZ PASS WITH LOW CONFIDENCE. THE INITIAL INTENSITY HAS BEEN REDUCED
TO 35 KNOTS BUT STILL HELD HIGHER THAN AGENCY DVORAK ESTIMATES;
HOWEVER, IT IS SUPPORTED BY SATCON DVORAK ESTIMATES RANGING FROM
T2.5-T2.6. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF
MODERATE (15-20 KNOT) VERTICAL WIND SHEAR (VWS) THAT IS PARTLY OFFSET
BY EQUATORWARD OUTFLOW AND A STORM MOTION THAT IS IN-PHASE WITH THE
UPPER AND LOW LEVEL WIND FLOW. HOWEVER, A TUTT CELL TO THE NORTHEAST,
JUST EAST OF GUAM, IS CAUSING SUBSIDENCE AND INHIBITING POLEWARD
OUTFLOW. SSTS IN THE REGION ARE VERY WARM AT 30 CELSIUS. THE CYCLONE
IS TRACKING ALONG THE SOUTHWESTERN EXTENSION OF A BUILDING
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THE PEAK INTENSIFICATION PHASE HAS BEEN ADJUSTED TOWARD THE
TERMINATION OF THE FORECAST, OTHERWISE, THERE IS NO CHANGE IN THE
FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. AT THE ONSET, TS 27W WILL DEVELOP AT A VERY SLOW RATE AS THE
LOW LEVEL CIRCULATION STRUGGLES TO CONSOLIDATE AND THE TUTT CELL
STIFLES POLEWARD OUTFLOW. TS 27W WILL GRADUALLY TRACK NORTHWESTWARD
IN THE WARM PHILIPPINE SEA AS THE STR CONTINUES TO BUILD AND STEER
THE SYSTEM. AS IT MOVES AWAY FROM THE TUTT CELL AND AS IT EVENTUALLY
CONSOLIDATES, TS 27W WILL INTENSIFY AT A NEAR CLIMATOLOGICAL RATE AND
REACH TYPHOON INTENSITY OF 65 KNOTS BY TAU 48. AFTER TAU 48, HOWEVER,
AS THE SYSTEM ENCOUNTERS STRONG VWS AHEAD OF AN APPROACHING
MID-LATITUDE TROUGH, THE INTENSITY WILL BE SUSTAINED AT BEST, MAYBE
EVEN REDUCED. NUMERIC MODEL GUIDANCE IS IN GOOD AGREEMENT DURING THIS
PORTION OF THE JTWC TRACK FORECAST, LENDING HIGH CONFIDENCE UP TO TAU
72.
   C. IN THE EXTENDED PERIOD, TS 27W WILL ROUND THE WESTERN EDGE OF
THE STR AND TURN MORE NORTHWARD THEN ACCELERATE NORTHEASTWARD, ON THE
FRONT EDGE OF THE AFOREMENTIONED MID-LATITUDE TROUGH. BY TAU 120 THE
CYCLONE WILL BE NEAR 30N, SOUTH OF HONSHU, JAPAN. INCREASED OUTFLOW
ASSOCIATED WITH THE MID-LATITUDE TROUGH AND IN PHASE-STORM MOTION
WILL PROMOTE A SECONDARY INTENSIFICATION PHASE, REACHING 90 KNOTS BY
END OF FORECAST. MODEL GUIDANCE SHOWS A LARGER SEPARATION IN THE
LATER TAUS WITH THE JAPANESE MODELS ON THE EXTREME RIGHT OF THE MODEL
ENVELOPE SHOWING AN UNREALISTIC TURN INTO THE STEERING RIDGE. THE
JTWC FORECAST TRACK IS HEDGED JUST LEFT OF THE MULTI-MODEL CONSENSUS
WITH LOW CONFIDENCE.//
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