Tropical Storm LIONROCK Advisory 23 Αυγ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (LIONROCK) WARNING
NR 21//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 12W (LIONROCK), LOCATED APPROXIMATELY 362 NM
EAST-NORTHEAST OF KADENA AB, HAS TRACKED SOUTHWARD AT 05 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS
TS 12W CONSOLIDATING INTO A WELL DEFINED SPIRAL BANDED SYSTEM IN THE
LAST SIX HOURS. A TIGHTLY WOUND LOW LEVEL CIRCULATION CENTER IS
VISIBLE IN A 230101Z MHS 89 GHZ IMAGE GIVING HIGH CONFIDENCE TO THE
INITIAL POSITION. THE INITIAL POSITION IS ASSESSED AT 45 KNOTS AND
IS BASED ON THE IMPROVING CONVECTIVE STRUCTURE AND OBJECTIVE DVORAK
FIXES FROM ALL AGENCIES REPORTING A CURRENT INTENSITY OF T3.0 (45
KNOTS). UPPER-LEVEL OUTFLOW HAS IMPROVED SLIGHTLY IN BOTH THE
POLEWARD AND EQUATORWARD CHANNELS, AND VERTICAL WIND SHEAR REMAINS
MODERATE NEAR 15 TO 20 KNOTS. SEA SURFACE TEMPERATURES ARE WARM NEAR
30 CELSIUS, BUT AVAILABLE OCEAN HEAT CONTENT IS RATHER LOW. TS 12W
IS CURRENTLY QUASI-STATIONARY DRIFTING TO THE SOUTH IN THE ABSENCE
OF A DOMINANT STEERING MECHANISM.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY FROM THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. IN THE NEAR FORECAST TS 12W WILL REMAIN QUASI-STATIONARY AS
TWO BUILDING RIDGES COMPETE AS THE DOMINANT STEERING RIDGE. A
SUBTROPICAL RIDGE (STR) TO THE NORTHWEST WILL HAVE MORE INFLUENCE IN
THE NEXT 48 HOURS TRACKING THE SYSTEM SOUTH AND EVENTUALLY
SOUTHWEST. A NEAR-EQUATORIAL RIDGE (NER) IS POSITIONED TO THE
SOUTHEAST AND WILL COUNTER THE INFLUENCE OF THE SUBTROPICAL RIDGE.
INTENSIFICATION IS FORECAST TO BE GRADUAL AS OUTFLOW IS EXPECTED TO
IMPROVE AS THE TROUGH MOVES EAST. HOWEVER, ENHANCED OUTFLOW WILL BE
OFFSET BY THE LOW OCEAN HEAT CONTENT AS THE SYSTEM CHURNS UP
WATER UNDER ITS QUASI-STATIONARY TRACK.
   C. IN THE EXTENDED TAUS, THE NER WILL EVENTUALLY BUILD IN FROM
THE SOUTH-SOUTHEAST BECOMING THE DOMINANT STEERING RIDGE AROUND TAU
72 DRIVING THE SYSTEM ON A NORTHEAST TRACK. SIMULTANEOUSLY A
MIDLATITUDE TROUGH WILL MOVE INTO THE REGION ENHANCING OUTFLOW AND
TS 12W IS EXPECTED TO REACH TYPHOON STRENGTH BY TAU 72 REACHING A
PEAK INTENSITY OF 75 KNOTS. DYNAMIC MODEL GUIDANCE IS IN AGREEMENT
THAT THE SYSTEM WILL REMAIN QUASI-STATIONARY OVER THE NEXT FEW DAYS
AND EVENTUALLY TAKE A NORTHEASTWARD TRACK DUE TO THE ESTABLISHMENT
OF THE NER. HOWEVER, THE SOLUTIONS ARE IN SHARP DISAGREEMENT AS TO
THE EXACT POSITION AND TIMING OF THE TRACK SHIFTS. DUE TO THE
COMPLEXITY OF THE STEERING ENVIRONMENT, THERE IS LOW CONFIDENCE IN
FORECAST TRACK.//
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