Tropical Storm SAOLA Advisory Sun Oct 22

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 27W (TWENTYSEVEN)
WARNING NR 07//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 27W (TWENTYSEVEN), LOCATED APPROXIMATELY 253
NM EAST-SOUTHEAST OF ANDERSEN AFB, HAS TRACKED WEST-SOUTHWESTWARD AT
07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A WELL-DEFINED FULLY EXPOSED LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH VERY LIMITED CENTRAL CONVECTION OVER
THE LAST SIX HOURS. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE EXPOSED LLCC EVIDENT IN SATELLITE IMAGERY.
THE INITIAL INTENSITY IS ASSESSED AT 30 KNOTS BASED LARGELY ON
PERSISTENCE FROM PREVIOUS DVORAK ESTIMATES OF T2.0 (30KTS), A
202313Z OSCAT IMAGE SHOWING A SOLID REGION OF 30 KNOT WIND BARBS ON
THE SOUTHWESTERN PERIPHERY, AND A 210548Z SATCON ESTIMATE OF 33
KNOTS. UPPER-LEVEL ANALYSIS SHOWS A TUTT CELL TO THE NORTH, WHICH
PREVIOUSLY PROVIDED AN OUTFLOW MECHANISM, HAS DETERIORATED UNDER THE
INFLUENCE OF A BUILDING RIDGE TO THE NORTHEAST. INCREASING EASTERLY
FLOW FROM THE RIDGE HAS ALSO LED TO A RAPIDLY DETERIORATING SHEAR
ENVIRONMENT. SSTS IN THE REGION ARE VERY WARM IN EXCESS OF 30
CELSIUS, BUT THE DETERIORATING UPPER-LEVELS HAVE THUS FAR HINDERED
THE POSSIBILITY OF FURTHER DEVELOPMENT. TD 27W IS TRACKING SLOWLY
WEST-SOUTHWESTWARD WITHIN A COMPETING STEERING ENVIRONMENT.
3. FORECAST REASONING.
   A. NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TD 27W IS POSITIONED WITHIN A COMPETING STEERING ENVIRONMENT
WITH MID-TO-LOW LEVEL RIDGES POSITIONED TO BOTH THE SOUTHWEST AND
NORTHEAST. THE SYNOPTIC SETUP WILL RESULT IN A SLOW AND UNCERTAIN
TRACK MOTION OVER THE NEXT 48 HOURS. THE WESTERN RIDGE IS FORECAST
TO BUILD BECOMING SLIGHTLY MORE DOMINANT AND RESULTING IN A TRACK
SOUTH TO SOUTHWEST OVER THE NEXT 36 HOURS. BEYOND TAU 36, THE
WESTERN RIDGE IS EXPECTED TO WEAKEN RETREATING TO THE SOUTHWEST
WHILE THE EASTERN RIDGE STRENGTHENS, ACCELERATING TD 27W ON A
NORTHWESTWARD TRACK. INTENSE EASTERLY FLOW ALOFT WILL PERSIST WHILE
TRAPPED BETWEEN THE TWO RIDGES MITIGATING THE LIKELIHOOD OF FURTHER
DEVELOPMENT.
   C. IN THE EXTENDED PERIOD, THE EASTERN STEERING RIDGE IS FORECAST
TO WEAKEN AND AROUND TAU 72 UPPER-LEVEL CONDITIONS WILL BECOME
INCREASINGLY FAVORABLE. SHOULD THE LLCC SURVIVE THE HOSTILE SHEAR
ENVIRONMENT, THE IMPROVING CONDITIONS ALOFT COUPLED WITH SSTS
REMAINING FAVORABLY WARM, TD 27W IS FORECAST TO BEGIN GRADUALLY
INTENSIFYING. AROUND TAU 96 THE STEERING RIDGE WILL WEAKEN
SUFFICIENTLY TO BEGIN SLOWING DOWN TD 27W, WITH THE POSSIBILITY OF
ENTERING A WEAK STEERING ENVIRONMENT AND SUBSTANTIAL UNCERTAINTY IN
THE TRACK BEYOND TAU 120. DYNAMIC MODEL GUIDANCE SHOWS GENERAL
AGREEMENT ON THE STEERING PHILOSOPHY, HOWEVER, THERE IS SUBSTANTIAL
UNCERTAINTY IN EXACT POSITION AND TIMING OF THE TURN THE NORTHWEST.
DUE TO THE LARGE DEGREE OF UNCERTAINTY IN THE OVER THE NEXT 48 HOURS
WHILE IN A COMPETING STEERING ENVIRONMENT, THERE IS LOW CONFIDENCE
IN THE JTWC FORECAST.//
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