WDPN33 PGTW 161500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (FRANCISCO) 
WARNING NR 03//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 26W (FRANCISCO), LOCATED APPROXIMATELY 167 NM
SOUTHWEST OF ANDERSEN AFB, GUAM, HAS TRACKED SOUTHWESTWARD AT 15
KNOTS OVER THE PAST SIX HOURS. RECENT ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH A RAGGED
CENTRAL DEEP CONVECTION THAT HAS SLIGHTLY DEEPENED. FORMATIVE BANDING
FROM THE SOUTHERN PERIPHERY HAS SPIRALED TIGHTER INTO A BROAD LOW
LEVEL CIRCULATION CENTER. THE INITIAL POSITION IS BASED ON A
LONG-RANGE BASE REFLECTIVITY RADAR LOOP FROM NWS GUAM AND
EXTRAPOLATED FROM A 161026Z SSMI/S MICROWAVE PASS WITH FAIR
CONFIDENCE. THE INITIAL INTENSITY OF 35 KNOTS IS SUPPORTED BY
AUTOMATED DVORAK DATA AND IS SLIGHTLY HIGHER THAN CONGRUENT
SUBJECTIVE DVORAK ESTIMATES FROM RJTD AND PGTW OF 30 KNOTS TO REFLECT
THE DEVELOPING TREND. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS 20
DEGREES SOUTHEAST OF THE SUBTROPICAL RIDGE (STR) AXIS IN AN AREA OF
LIGHT (05 TO 10 KNOT) VERTICAL WIND SHEAR (VWS). ADDITIONALLY, A
STRONG EQUATORWARD OUTFLOW IS EVIDENT ON ANIMATED WATER VAPOR
IMAGERY. THE CYCLONE IS TRACKING ALONG THE OUTER PERIPHERY OF A
MID-LAYER REFLECTION OF THE STR.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS
PROGNOSTIC REASONING MESSAGE. 
   B. IN THE NEAR TERM, TS 26W IS EXPECTED TO CONTINUE ALONG ITS
CURRENT TRACK. AFTER TAU 12, THE STR, WHICH IS CURRENTLY BUILDING,
WILL RECEDE EASTWARD CAUSING THE SYSTEM TO TURN NORTHWARD. AFTER TAU
48, THE STR WILL CONTINUE TO BUILD AND STEER TS 26W TO A MORE
NORTHWESTWARD TRAJECTORY. DURING THIS PHASE, THE CYCLONE WILL
APPROACH THE MID-LATITUDE WESTERLIES AND TAP INTO A POLEWARD OUTFLOW
CHANNEL. THIS NEW DIVERGENT MECHANISM, IN ADDITION TO THE CONTINUED
FAVORABLE DYNAMICS DISCUSSED IN PARAGRAPH 2, WILL ENHANCE FURTHER
RAPID INTENSIFICATION. THE SYSTEM WILL REACH 105 KNOTS BY TAU 72.
   C. TS FRANCISCO WILL CONTINUE TO INTENSIFY EVEN AFTER TAU 72,
MOSTLY DUE TO THE DUAL OUTFLOW CHANNELS, PEAKING AT 115 KNOTS BY TAU
96. AFTERWARDS, THE SYSTEM WILL SLOWLY WEAKEN DUE TO INCREASING VWS
AND COOLING SEA SURFACE TEMPERATURES. THE NUMERIC MODEL GUIDANCE IS
IN FAIR AGREEMENT; HOWEVER, GIVEN THE DEVELOPMENTAL STAGE OF THE
SYSTEM AND THE ANTICIPATED CHANGES IN THE STEERING FLOW, THE JTWC
TRACK FORECAST IS LAID CLOSE TO THE MULTI-MODEL CONSENSUS WITH LOW
CONFIDENCE.  //
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