WDPN33 PGTW 290900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (HAIKUI) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.0N 137.2E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 416 NM SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: WESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND MICROWAVE
IMAGERY OVER THE PAST SIX HOURS STRONGLY SUGGESTED THAT TROPICAL
STORM (TS) 10W (HAIKUI) WAS UNDERGOING A PERIOD OF SYMMETRIZATION
AND INTENSIFICATION. HOWEVER, IMAGERY RECEIVED SUBSEQUENT TO THE
ANALYSIS TIME STRONGLY SUGGESTS THAT THE SYSTEM HAS IN FACT BECOME
SIGNIFICANTLY SHEARED. RECENT ANIMATED VISIBLE IMAGERY SHOWS DEEP
CONVECTION FIRING NEAR THE ASSESSED INITIAL POSITION, BUT IT
REMAINS RELATIVELY DISORGANIZED AT THE PRESENT TIME. A 200433Z
AMSR2 89GHZ MICROWAVE IMAGE SHOWED A CLEAR MICROWAVE EYE AND THE
COLOR ENHANCED 37GHZ IMAGE SHOWED WHAT APPEARED TO BE A VERTICALLY
STACKED EYE FEATURE SURROUNDING BY POCKETS OF DEEP CONVECTION. A
290739Z SSMIS SERIES TELLS A MUCH DIFFERENT TALE HOWEVER, WITH A
FALSE 36GHZ MICROWAVE EYE UNDER A POCKET OF STRONG CONVECTION,
WHILE THE 91GHZ IMAGE SHOWS WELL-DEFINED LOW-LEVEL BANDS DISPLACED
TO THE EAST OF THE DEEP CONVECTIVE CORE. CIMSS AUTOMATED SHEAR
ANALYSIS SHOWS NEAR 20 KNOTS OF EASTERLY SHEAR, AND THE
HIGH-RESOLUTION GFS VORTEX AVERAGED SKEW-T SUPPORTS THIS ASSESSMENT
AS DOES ANALYSIS OF ANIMATED WATER VAPOR IMAGERY. THUS, THE INITIAL
POSITION, WHILE ORIGINALLY ASSESSED WITH HIGH CONFIDENCE, IS NOW
ASSESSED WITH MEDIUM OR EVEN LOW CONFIDENCE AND MAY IN FACT BE MUCH
FURTHER TO THE EAST. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE AND WAS HEDGED HIGHER THAN THE BULK OF THE SUBJECTIVE
AND OBJECTIVE INTENSITY ESTIMATES BASED ON THE EYE FEATURE IN THE
AMSR2 IMAGERY. THE OVERALL ENVIRONMENT IS WEAKLY FAVORABLE, WITH
WARM SSTS AND GOOD EQUATORWARD OUTFLOW BEING TEMPERED BY THE
MODERATE TO STRONG EASTERLY SHEAR AS WELL THE PRESENCE OF A WEDGE
OF DRY AIR TO THE NORTH.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE NORTH. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T2.5 - 35 KTS
   CIMSS SATCON: 47 KTS AT 290423Z
   CIMSS ADT: 45 KTS AT 290530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 20-25 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: DRY AIR TO THE NORTH. 

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: WITH THE MOST RECENT ANALYSIS SUGGESTING A
LOW-CONFIDENCE INITIAL POSITION AND INTENSITY, AND A NEW SET OF
MODEL GUIDANCE COMING IN WHICH SHOWS A MASSIVE DIVERGENCE IN THE
MODEL TRACKERS, THE UP-FRONT ASSESSMENT OF THE FORECAST IS VERY LOW
CONFIDENCE WITH A VERY HIGH DEGREE OF UNCERTAINTY. THE SYSTEM IS
FORECAST TO CONTINUE TRACKING NORTHWESTWARD ALONG THE SOUTHWEST
SIDE OF THE STR TO THE NORTH. THROUGH TAU 48, THE BULK OF THE
GUIDANCE SUPPORTS THIS FORECAST BUT EVEN AS EARLY AS THIS, THE GFS,
HAFS-A AND COAMPS-TC (GFS) AND THE GEFS ENSEMBLE AND THE ECMWF AND
ECENS ENSEMBLE, BEGIN TO JUMP SHIP FROM THE REST OF THE PACK,
ALBEIT ON OPPOSITE SIDES OF THE SHIP. IN THE GFS GLOBAL MODEL, THE
EVOLUTION OF THE RIDGE PATTERN IS SO DIFFERENT FROM THE ECMWF
DEPICTION AS WELL AS FROM THE MOST RECENT PREVIOUS RUN, AS TO DEFY
UNDERSTANDING. IN THE GFS, THE STR TO THE NORTH RIDGES SHARPLY
SOUTHWESTWARD, AND EVENTUALLY DEVELOPS INTO A NEW STR CENTERED NEAR
SHANGHAI BY AROUND TAU 96. THE RESULT OF THIS PROCESS IS THAT THE
GFS STOPS THE SYSTEM MOVING POLEWARD AFTER TAU 48, TURNS THE SYSTEM
WEST AND THEN SOUTH AND BY TAU 120 SHOWS THE SYSTEM PARKED NEAR 20N
126E. MEANWHILE THE ECMWF SHOWS A RIDGE CURRENTLY CENTERED EAST OF
SHANGHAI BUT DISSIPATES THIS RIDGE WITHIN THE NEXT 48 HOURS,
REPLACED BY A MUCH LESS EXPANSIVE STR TO THE NORTHEAST. THIS ALLOWS
TS 09W TO TRACK NORTHWEST THROUGH TAU 72, THEN TURN NORTHWARD AFTER
TAU 72 AS IT ROUNDS THE RIDGE AXIS AND RIDES UP A TROUGH MOVING IN
FROM THE WEST, SUCH THAT THE TAU 120 POSITION OF ECMWF IS JUST WEST
OF KUNSAN, SOUTH KOREA. WITH THIS RUN BEING THE FIRST TO SHOW SUCH
LARGE BIFURCATION IN THE MODEL DATA, THERE IS NO MAJOR SHIFT IN
THE JTWC FORECAST TRACK, WHICH REMAINS NESTLED CLOSELY TO THE
CONSENSUS MEAN. IN TERMS OF INTENSITY, THE SYSTEM IS FORECAST TO
REMAIN UNDER THE INFLUENCE OF THE MODERATE EASTERLY SHEAR FOR THE
NEXT 24 TO 48 HOURS, WHICH WILL INHIBIT AND SLOW THE PACE OF
INTENSIFICATION. A RESPITE FROM THE SHEAR IS EXPECTED BY AROUND TAU
48, WHICH SHOULD ALLOW THE SYSTEM TO INTENSIFY MORE QUICKLY, TO A
PEAK OF 90 KNOTS BY TAU 72. AFTER ENTERING THE EAST CHINA SEA THE
COMBINATION OF DECREASED SSTS AND DRY AIR ENTRAINMENT WILL LEAD TO
A STEADY WEAKENING THROUGH THE REMAINDER OF THE FORECAST. 

MODEL DISCUSSION: AS DISCUSSED ABOVE, THERE ARE SIGNIFICANT
DIFFERENCES BETWEEN THE GFS AND ECMWF AND THEIR ENSEMBLES, LEADING
TO A BIFURCATION SCENARIO, WITH A 925NM SPREAD BETWEEN THE
DETERMINISTIC TRACKERS AT TAU 120. THE INTERESTINGLY, THE GFS
ENSEMBLE MEAN TRACKER REMAINS CONSISTENT WITH THE CONSENSUS MEAN,
WHICH MAY PROVIDE A HINT THAT THE 0000Z DETERMINISTIC RUN IS AN
ANOMALY. IN LIGHT OF THE LARGE SPREAD, THERE IS EXTREMELY LOW
CONFIDENCE IN THE JTWC FORECAST TRACK. INTENSITY GUIDANCE IS
SIMILARLY SPREAD ACROSS A WIDE RANGE BETWEEN 55 KNOTS TO 125 KNOTS.
SEVERAL RAPID INTENSIFICATION (RI) AIDS HAVE BEEN TRIGGERED BUT THE
HAFS-A AND COAMPS-TC GUIDANCE DO NOT SUPPORT RI EXPLICITLY, AT
LEAST NOT IN THE NEAR-TERM. THE COAMPS-TC ENSEMBLE PROBABILISTIC
INTENSITY GUIDANCE SHOWS A HIGH PROBABILITY OF RI IN THE LATER TAUS
AROUND TAU 84, BUT THE TRACK AT THAT TIME IS CLOSE TO THE GFS
TRACKER DISCUSSED ABOVE, AND THUS IS DISCOUNTED AS PART OF THIS
FORECAST. THE JTWC FORECAST LIES CLOSE BUT JUST BELOW THE CONSENSUS
MEAN, WITH LOW CONFIDENCE. 

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