WDPN32 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (GAEMI) WARNING 
NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.7N 127.7E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 588 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
TROPICAL DEPRESSION (TD) 05W (GAEMI) WITH MORE PRONOUNCED DEEP 
CONVECTION THAT IS BEGINNING TO BUILD OVER THE CENTER OF THE LOW-LEVEL
CIRCULATION CENTER (LLCC). THE LLCC IS STILL SLIGHTLY OFFSET TO THE
EAST OF THE DEEP CONVECTION BUT APPEARS TO HAVE BECOME MORE
VERTICALLY ALIGNED OVER THE PAST 6 HOURS. EASTERLY SHEAR CONTINUES
TO BE EVIDENT IN THE ANIMATED EIR, WITH MODELS SUGGESTING AROUND 20
KTS CURRENTLY. ENVIRONMENTAL ANALYSIS INDICATES THAT 05W IS IN A
MARGINALLY FAVORABLE ENVIRONMENT CHARACTERIZED BY GOOD POLEWARD
OUTFLOW ALOFT ENHANCED BY A TUTT CELL LOCATED TO THE EAST-NORTHEAST
OF THE SYSTEM, WARM (30-31 C) SEA SURFACE TEMPERATURES, SLIGHTLY
OFFSET BY THE LOW TO MODERATE (15-20 KTS) EASTERLY SHEAR. THE
INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE
PARTIALLY EXPOSED LLCC SEEN IN THE ANIMATED IMAGERY. THE INITIAL
INTENSITY OF 30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW.
ADDITIONALLY, A 201214Z ASCAT-C PARTIAL PASS REVEALS 25 KNOT WINDS
ABOUT 60 NM NORTHEAST OF THE CIRCULATION CENTER.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED SOUTH OF HONSHU.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.5 - 35 KTS
   CIMSS ADT: 34 KTS AT 201200Z
   CIMSS AIDT: 34 KTS AT 201200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TD 05W IS FORECAST TO CONTINUE TRACKING
NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF THE STR THROUGH TAU
24. AFTER TAU 24, THE SYSTEM IS FORECAST TO TAKE A MORE
NORTH-NORTHWESTWARD TRACK AS THE STR REORIENTS TO A NORTH-SOUTH
ORIENTATION IN RESPONSE TO A MID-LATITUDE TROUGH WHICH PROPAGATES
OVER THE KOREAN PENINSULA. 05W IS ANTICIPATED TO CONTINUE ALONG
THIS TRACK THROUGH TAU 96 WHEN RIDGING OVER EASTERN CHINA TAKES
OVER THE STEERING AND DRIVES THE SYSTEM BACK MORE NORTHWESTWARD.
CONCERNING THE INTENSITY FORECAST, 05W IS FORECAST TO GRADUALLY
INTENSIFY OVER THE NEXT 72 HOURS TO AROUND 75 KTS DUE TO WARM SST
AND HIGH OHC VALUES BUT WILL BE HINDERED BY HIGH VERTICAL WIND
SHEAR VALUES (20-25 KTS) DURING THE PERIOD. AFTER TAU 72, VWS
VALUES ARE EXPECTED TO DROP DRASTICALLY AND WILL ALLOW FOR MORE
ROBUST INTENSIFICATION WITH A PEAK INTENSITY FORECAST TO BE AROUND
100 KTS AT TAU 96. NEAR THE END OF THE FORECAST PERIOD, 05W IS
FORECAST TO BEGIN WEAKENING WITH COOLER SST AND LAND INTERACTION
WITH EASTERN CHINA BECOMING A FACTOR. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 72, WITH A 180 NM CROSS-TRACK SPREAD AT TAU 72, WHICH
INCREASES TO AROUND 400 NM AT TAU 120, WITH ALL GUIDANCE TRACKING
THE SYSTEM WEST OF OKINAWA. UKMET AND GALWEM MAKE UP THE
WESTERNMOST MEMBERS, TRACKING THE SYSTEM ACROSS NORTHERN TAIWAN.
THE JTWC TRACK IS PLACED TO THE EAST OF CONSENSUS TO OFFSET THE
OUTLIERS. OVERALL, THE JTWC TRACK FORECAST IS PLACED WITH HIGH
CONFIDENCE THROUGH TAU 72, AND MEDIUM CONFIDENCE THEREAFTER.
INTENSITY GUIDANCE AGREES THROUGH TAU 72 AS WELL, DEPICTING A
STEADY INTENSIFICATION PHASE TO AROUND 65-85 KTS. AFTER TAU 72,
MODELS VARY ON PEAK INTENSITIES RANGING FROM 90-120 KTS. THE JTWC
INTENSITY FORECAST IS PLACED BETWEEN THE TWO POSSIBILITIES, ALONG
WITH THE MAJORITY OF MEMBERS, AT AROUND 100 KTS. THE JTWC INTENSITY
FORECAST IS THEREFORE ASSESSED WITH MEDIUM CONFIDENCE THROUGH THE
FORECAST PERIOD.

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