WDXS32 PGTW 222100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (ENALA) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.8S 73.2E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 524 NM SOUTH OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A
TIGHTLY-CURVED CORE OF DEEP CONVECTION THAT HAS BECOME BETTER
ORGANIZED IN APPEARANCE OVER THE PAST 12 HOURS. A 221542Z AMSU-B
MICROWAVE IMAGE IN FACT SHOWED A WELL-DEFINED, NEARLY CLOSED
EYEWALL ABOUT 25-30 NM IN DIAMETER. AN EARLIER 221225Z GMI
MICROWAVE PASS REVEALED THAT THE VORTEX WAS TILTED SOUTHWESTWARD
WITH HEIGHT AT THAT TIME, CONSISTENT WITH AN EXPECTED
RIGHT-OF-SHEAR TILT WITH RESPECT TO THE CURRENTLY NORTHWESTERLY
SHEAR VECTOR OF AROUND 15 KT MAGNITUDE. LIGHT NORTHERLY UPPER
TROPOSPHERIC WINDS CONTRIBUTING TO THIS SHEAR ARE RESTRICTING
UPPER-LEVEL OUTFLOW ON THE NORTHERN SIDE OF THE CYCLONE, BUT
ENHANCING OUTFLOW IN THE SOUTHERN SEMICIRCLE, AIDED BY AN UPPER
TROPOSPHERIC TROUGH TO THE SOUTHWEST OF THE STORM. THE INITIAL
INTENSITY IS SET AT 50 KT BASED ON A BLEND OF AGENCY DVORAK
ESTIMATES AND OBJECTIVE SATELLITE-DERIVED ESTIMATES RANGING FROM 35
TO 55 KT, LEANING TOWARD THE HIGH SIDE OF THAT RANGE DUE TO THE
ORGANIZED INNER CORE STRUCTURE.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: MID-LEVEL RIDGE TO THE SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   DEMS: T2.5 - 35 KTS
   FMEE: T3.0 - 45 KTS
   FIMP: T3.0 - 45 KTS
   CIMSS ADT: 53 KTS AT 221800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DEEP-LAYER DRY AIR MASS ADJACENT TO NORTHERN SIDE
OF THE CIRCULATION

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: LOW
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL CYCLONE 14S (ENALA) HAS A
WELL-ORGANIZED INNER CORE, THOUGH TILTED WITH HEIGHT DUE TO
NORTHWESTERLY VERTICAL SHEAR OF ABOUT 15 KT. THE CIRCULATION IS
COMPACT AND POTENTIALLY VULNERABLE TO ENTRAINMENT OF THE DEEP-LAYER
DRY AIR MASS ON ITS NORTHERN SIDE, ADVECTED INWARD BY THE SHEAR.
THIS SHEAR WILL ALSO INTENSIFY SUBSTANTIALLY WITHIN 12-24 HOURS,
INCREASING TO 25-30 KT IN BOTH GFS AND ECMWF MODEL FORECASTS AS AN
UPPER-LEVEL TROUGH TO THE SOUTHWEST AND A MID-LEVEL RIDGE TO THE
SOUTHEAST COMBINE TO IMPOSE NORTHWESTERLY FLOW IN THE MID TO UPPER
TROPOSPHERE OVER THE CYCLONE. HOWEVER, UPPER-LEVEL OUTFLOW WILL
REMAIN STRONG INTO THE UPPER TROUGH AS A JET STREAK INTENSIFIES TO
THE SOUTH AND SOUTHEAST OF ENALA, WHICH WILL CONTINUE TO FACILITATE
VIGOROUS CONVECTION. SEA SURFACE TEMPERATURES OF 26-27 DEGREES
CELSIUS ALONG THE FORECAST TRACK WILL ALSO SUPPORT DEEP CONVECTION.
ENALA IS THUS FORECAST TO MAINTAIN AN INTENSITY IN THE 45-55 KT
RANGE AS FAVORABLE AND UNFAVORABLE ENVIRONMENTAL FACTORS
COUNTERBALANCE EACH OTHER. THIS INTENSITY FORECAST HAS SOME ADDED
UNCERTAINTY DUE TO ENALA BEING A SMALL, TILTED CYCLONE THAT IS
LIKELY TO RETAIN BOTH OF THESE CHARACTERISTICS FOR SEVERAL DAYS.
THIS STORM STRUCTURE IS PRONE TO QUICK INTENSITY CHANGES EITHER UP
OR DOWN DUE TO ITS COMPACT INNER CORE AND ABOVE-AVERAGE SENSITIVITY
TO VERTICAL SHEAR AND DRY AIR. FOR NOW, NUMERICAL MODEL GUIDANCE IS
GENERALLY IN CONSENSUS WITH THE JTWC INTENSITY FORECAST. THE TRACK
FORECAST FOR ENALA IS STRAIGHT FORWARD AS THE MID-LEVEL RIDGE TO
THE SOUTHEAST DIRECTS THE STORM SOUTHWESTWARD OR
SOUTH-SOUTHWESTWARD OVER OPEN WATER FOR THE NEXT 72 HOURS. BEYOND
72 HOURS, UNCERTAINTY INCREASES AS THE UPPER-LEVEL TROUGH TO THE
SOUTHWEST IS FORECAST TO ERODE, LEAVING ENALA IN WEAKER DEEP-LAYER
STEERING CURRENTS. ITS MOTION DURING THE 72-120 HOUR PERIOD WILL
DEPEND ON ITS INTENSITY, WITH A WEAKER, DECOUPLED VORTEX TRACKING
MORE WESTWARD, AND A STRONGER VORTEX TRACKING MORE SOUTH OR
SOUTHEASTWARD. THE JTWC FORECAST SHOWS A SLOWING SOUTHWESTWARD
MOTION DURING 96-120 HOURS, FOLLOWING THE MULTI-MODEL CONSENSUS.

MODEL DISCUSSION: THE JTWC INTENSITY AND TRACK FORECASTS ARE CLOSE
TO THE MULTI-MODEL CONSENSUS, WHICH HAS MODERATE SPREAD IN BOTH
TRACK AND INTENSITY. THE TRACK FORECAST IS SLIGHTLY SOUTHEAST OF
THE PREVIOUS FORECAST BEYOND 72 HOURS. THE INTENSITY FORECAST IS A
NOTCH WEAKER BEYOND 48 HOURS.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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