WDPN33 PGTW 140900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (NANMADOL) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.9N 140.6E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 120 NM SOUTH-SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: AN 
IMPROVING SYSTEM WITH DEFINED FEEDER BANDS WRAPPING INTO AN ASSESSED 
LOW LEVEL CIRCULATION CENTER (LLCC). IN ADDITION, THERE ARE PLUMES OF 
CONVECTIVE ACTIVITY NEAR THE CENTER AND IN THE OUTER BANDS TO THE WEST 
AND SOUTH OF THE LLCC. FURTHER ANALYSIS REVEALS THAT TS 16W IS 
BEGINNING TO SLOW DOWN IN TRACK SPEED AS IT WILL EVENTUALLY MAKE THE 
TURN NORTHWESTWARD. UNFORTUNATELY THERE HAS BEEN LIMITED USABLE 
MICROWAVE DATA DURING THIS WARNING CYCLE FOR TS NANMADOL. A PARTIAL 
140327Z AMSR2 36 GHZ PASS SHOWS THE ASSESSED LLCC AND INCREASE IN 
CONVECTIVE ACTIVITY IN THE AFOREMENTIONED REGIONS OF THE SYSTEM. THE 
ENVIRONMENT IS MARGINALLY FAVORABLE FOR FURTHER DEVELOPMENT WITH LOW 
(05-10 KTS) VERTICAL WIND SHEAR (VWS), AND WARM (29-30) SEA SURFACE 
TEMPERATURES (SSTS), OFFSET BY VERY WEAK RADIAL OUTFLOW ALOFT. THE 
SYSTEM CONTINUES TO DRIFT NORTHEASTWARD UNDER A WEAK STEERING 
ENVIRONMENT.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WEAK STEERING DUE TO COMPETING
MECHANISMS


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 46 KTS AT 140416Z
   CIMSS ADT: 35 KTS AT 140540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG EQUATORWARD
   OTHER FACTORS: DEEP TROPICAL MOISTURE INFLOW

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: FORECAST DISCUSSION: THE SUBTROPICAL RIDGE (STR) 
SITTING TO THE NORTH IS EXPECTED TO BECOME THE DOMINANT STEERING 
MECHANISM OVER THE COURSE OF THE NEXT 6 TO 12 HOURS. AS A RESULT, TS 
NANMADOL WILL MAKE THE TURN WEST-NORTHWESTWARD AND INTENSIFY AS IT 
RIDES THE SOUTHWEST PORTION OF THE STR. ON OR ABOUT TAU 12, TD 16W 
WILL INCREASE IN INTENSITY TO 55 KTS AND CONTINUE ON THIS TRAJECTORY 
AND INCREASE TO 65 KTS BY TAU 24. BY TAU 36, THE SYSTEM WILL BEGIN TO 
TAKE A MORE NORTHWESTWARD HEADING AS THE STR WILL WEAKEN DUE TO AN 
APPROACHING MAJOR SHORT WAVE TROUGH FROM THE WEST. AT THIS TIME, THE 
INTENSITY WILL INCREASE TO 85 KTS. THE PEAK INTENSITY OF 100 KTS WILL 
BE REACHED AT TAU 72 AS TS 16W ROUNDS THE RIDGE AXIS AND HEADS NORTH-
NORTHWESTWARD. BY TAU 96, TS NANMADOL WILL BEGIN TO DECREASE IN 
INTENSITY TO 95 KTS AS IT WILL BEGIN TO FEEL THE AFFECTS OF LAND 
INTERACTION WITH KYUSHU TO THE NORTH. BY TAU 120, THERE WILL BE 
ANOTHER DECREASE IN INTENSITY TO 75 KTS DUE TO THE SYSTEM BEING OVER 
LAND IN NORTHWEST KYUSHU.

MODEL DISCUSSION: MODEL DISCUSSION: THE TRACK MODEL CONSENSUS
MEMBERS ARE BACK IN A TIGHTER AGREEMENT THAN THE PREVIOUS MODEL
RUNS. THERE IS A 45NM SPREAD AT TAU 24. THIS IS TAKING NAVGEM INTO
ACCOUNT WHICH IS THE OUTLIER WITH A MORE NORTHWESTERLY TRACK THAN
THE OTHER CONSENSUS MEMBERS. BY TAU 72 THE SPREAD INCREASES TO
140NM, AND CONTINUES TO SPREAD TO 290NM THE LATER TAUS. THE JTWC
FORECAST TRACK IS SET WITH MEDIUM CONFIDENCE TO TAU 72, DUE TO THE 
TURN TO THE WEST-NORTHWEST THAT HAS YET TO HAPPEN. THEN THE FORECAST 
TRACK SET WITH LOW CONFIDENCE OUT TO TAU 120 DUE TO THE SPORADIC 
BEHAVIOR IN THE MODELS IN THE LATER PORTION OF THE FORECAST PERIOD. 
THE INTENSITY GUIDANCE CONTINUES TO SHOW A GRADUAL INCREASE AS THE 
ENVIRONMENT WILL IMPROVE AS TS 16W BEGINS ITS WEST-NORTHWESTWARD 
TRACK. HOWEVER, AS PREVIOUSLY FORECAST, THIS WILL BE A RELATIVELY SLOW 
PROCESS. WITH THAT, THE JTWC FORECAST INTENSITY WAS PLACED SLIGHTLY 
LOWER THAN CONSENSUS THROUGH TAU 72, AND THEN MORE ALIGNED WITH 
CONSENSUS AFTER TAU 72. DUE TO THE UNCERTAINTY OF THE TIMING OF THE 
IMPROVING ENVIRONMENT, THERE IS LOW CONFIDENCE IN THE FORECAST 
INTENSITY PAST TAU 72.

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