WDPN32 PGTW 080300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (PODUL) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.1N 145.7E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 294 NM NORTH OF SAIPAN
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM 16W (PODUL) WITH A FULLY EXPOSED, EXTREMELY WELL-DEFINED
LOW-LEVEL CIRCULATION CENTER (LLCC). THE VIGOROUS BURSTS OF DEEP 
CONVECTION OVER THE CENTER HAVE LARGELY DISSIPATED AFTER 2200Z. A 
TIMELY 080019Z METOP-C ASCAT PASS REVEALED A COMPACT WIND FIELD WITH 
AN AREA OF 40 KTS WITHIN THE NORTHEASTERN PERIPHERY. A 072255Z GMI 37 
GHZ MICROWAVE IMAGE SHOWED A SMALL DEVELOPING MICROWAVE EYE FEATURE. 
ENVIRONMENTAL ANALYSIS INDICATES THAT 16W IS IN A FAVORABLE 
ENVIRONMENT CHARACTERIZED BY MODERATE POLEWARD OUTFLOW ALOFT, LOW (10-
15 KTS) NORTHEASTERLY VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA 
SURFACE TEMPERATURES. THE NORTHEASTERLY SHEAR CONTINUES TO INHIBIT 
CENTRAL CONVECTION AND IS CAUSING A SOUTHWARD TILT OF THE VORTEX WITH 
HEIGHT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON 
THE EXPOSED LLCC IN ANIMATED MSI AND THE MENTIONED MICROWAVE IMAGES. 
THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH MEDIUM CONFIDENCE 
BASED ON THE ASCAT IMAGE AS WELL AS THE LISTED OBJECTIVE INTENSITY 
ESTIMATES. THE COMPACT NATURE OF THE SYSTEM IS LIKELY CAUSING THE 
OBJECTIVE ESTIMATES TO UNDERESTIMATE THE INTENSITY.

INITIAL WIND RADII BASIS: 080019Z METOP-C ASCAT SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED FAR TO THE NORTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 40 KTS AT 072108Z
   CIMSS ADT: 35 KTS AT 080010Z
   CIMSS AIDT: 37 KTS AT 080010Z
   CIMSS D-MINT: 33 KTS AT 072253Z
   CIMSS D-PRINT: 36 KTS AT 080010Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: VORTEX TILTED SOUTHWARD WITH HEIGHT

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 16W IS FORECAST TO CONTINUE TRACKING
NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL
RIDGE THROUGH TAU 24. AFTER TAU 24, THE SUBTROPICAL RIDGE IS
EXPECTED TO BUILD AND EXTEND ALL THE WAY TO EASTERN CHINA. THIS
WILL CAUSE THE TRAJECTORY TO BECOME MORE WESTWARD THROUGH TAU 96 AS
THE SYSTEM TRACKS ALONG THE SOUTHERN PORTION OF THE EXTENSION OF
THE RIDGE. AFTER TAU 96, 16W WILL TRACK SLIGHTLY MORE
WEST-NORTHWESTWARD AS THE LARGE DEEP-LAYER RIDGE SHIFTS AND ANCHORS
ITSELF OVER SOUTHERN HONSHU. REGARDING INTENSITY, 16W IS FORECAST
TO STEADILY INTENSIFY THROUGH TAU 48 TO AROUND 75 KTS AS THE
ENVIRONMENT REMAINS FAVORABLE. HOWEVER, IF THE VORTEX IS UNABLE TO
BECOME VERTICALLY ALIGNED WITH CENTRAL CONVECTION, A MUCH WEAKER
SYSTEM COULD OCCUR. NEAR TAU 72, SOME ENHANCED UPPER-LEVEL
EASTERLIES WILL CAUSE VERTICAL WIND SHEAR TO INCREASE TO AROUND 30
KTS AND CAUSE THE SYSTEM TO TEMPORARILY STOP INTENSIFYING. AFTER
TAU 96, THE UPPER-LEVEL EASTERLIES WILL WEAKEN, AND ALLOW FOR 16W
TO BEGIN INTENSIFYING AGAIN. OF NOTE, A FURTHER NORTHWARD TRACK WILL 
CAUSE 16W TO EXPERIENCE MUCH MORE SHEAR, AND THEREFORE, BE WEAKER. IF 
THE WESTWARD TRACK IS FURTHER SOUTH, CLOSER TO THE 20-21ST LATITUDE,
SHEAR WILL LIKELY HAVE LESS IMPACTS ON THE SYSTEM.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT WITH THE EXCEPTION OF THE UKMET DETERMINISTIC TRACKER,
WHICH TRACKS THE VORTEX MUCH FURTHER POLEWARD THAN THE REMAINDER OF
GUIDANCE. TAKING OUT THE OUTLIER, THERE IS A 130 NM CROSS-TRACK
SPREAD AT TAU 72, WHICH OPENS UP TO 170 NM AT TAU 120. THE JTWC
TRACK FORECAST IS PLACED WITH OVERALL MEDIUM CONFIDENCE, IN LINE
WITH THE BULK OF GUIDANCE. INTENSITY GUIDANCE CONTINUES TO BE IN
POOR AGREEMENT WITH GLOBAL MODELS CONTINUING TO BE CONSIDERABLY
WEAKER THAN THE MESOSCALE MODELS. THE JTWC INTENSITY FORECAST REMAINS 
CLOSER TO THE MESOSCALE MODELS, PARTICULARLY HAFS-A, WITH OVERALL LOW 
CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: LOW
   INTENSITY 72-120 HR: LOW//
NNNN