WDXS31 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (FREDDY) WARNING NR 045//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.5S 39.6E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 38 NM WEST-SOUTHWEST OF EUROPA ISLAND
   MOVEMENT PAST 6 HOURS: EASTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
AVAILABLE METEOROLOGICAL DATA SUPPORTS THE REGENERATION OF TC 11S, THEREFORE, JTWC HAS RESUMED WARNINGS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 041122Z GMI 89 GHZ IMAGE DEPICT A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) UNDER THE NORTHWEST PORTION OF AN AREA OF FLARING CONVECTION. THE COMPARISON BETWEEN THE 040800Z AND 041000Z SURFACE OBSERVATIONS FROM EUROPA ISLAND SHOWED A 4MB DROP FROM 1000MB TO 996MB RESPECTIVELY, WITH MAX REPORTED WINDS OF 33 KNOTS AT 041000Z. ENVIRONMENTAL ANALYSIS REVEALS TC 11S IS DEALING WITH A GOOD AMOUNT OF DRY AIR ENTRAINMENT IN THE WESTERN PERIPHERY, BUT THAT IS NOT EXPECTED TO LAST. TC FREDDY IS IN A FAVORABLE ENVIRONMENT FOR FURTHER TROPICAL DEVELOPMENT. THESE CONDITIONS ARE CHARACTERIZED BY ROBUST EASTWARD OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), AN INTENSE 850 MB VORTICITY SIGNATURE, AND VERY WARM (28-29 C) SEA SURFACE TEMPERATURES (SST). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE ABOVE MENTIONED MSI, MICROWAVE IMAGERY, AND MULTI-AGENCY FIXES. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE SET SLIGHTLY HIGHER THAN THE MULTI-AGENCY DVORAK ESTIMATES.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: THE NEAR EQUATORIAL RIDGE TO THE NORTH-NORTHEAST AND THE SUBTROPICAL RIDGE TO THE SOUTH-SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   FMEE: T2.5 - 35 KTS	

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG EASTWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.


FORECAST DISCUSSION: TC FREDDY HAS REGENERATED OVER THE SOUTHERN MOZAMBIQUE CHANNEL AFTER SPENDING THE PAST COUPLE OF DAYS STRUGGLING BETWEEN THE NEAR EQUATORIAL RIDGE TO THE NORTH-NORTHEAST AND THE SUBTROPICAL RIDGE TO THE SOUTH-SOUTHEAST. AFTER SPENDING SEVERAL HOURS IN A QUASI-STATIONARY POSTURE, TC FREDDY IS EXPECTED TO BE STEERED BY THE NER TO THE NORTH-NORTHEAST AND HEAD EAST-SOUTHEASTWARD THROUGH TAU 36. AS THIS OCCURS, TC 11S WILL GRADUALLY INCREASE IN INTENSITY TO 65 KTS. AFTERWARDS, TC FREDDY WILL MAKE A DRAMATIC TURN NORTHWESTWARD AS ANOTHER STR FROM THE SOUTHWEST BUILDS INTO THE AREA. WHILE HEADING NORTHWESTWARD, TC FREDDY WILL CONTINUE TO INCREASE IN INTENSITY TO 85 KNOTS BY TAU 96, THEN DROP TO 70 KNOTS BY TAU 120.

MODEL DISCUSSION: THE JTWC TRACK CONSENSUS MEMBERS ARE IN AGREEMENT SHOWING A CONTINUOUS EAST-SOUTHEASTWARD TRAJECTORY FOLLOWED BY A DRAMATIC TURN TO THE NORTHWEST AFTER TAU 36. HOWEVER, THERE IS A NOTABLE SPREAD FOR THE INDIVIDUAL CONSENSUS MEMBERS. BY TAU 12, THERE IS A 37 NM SPREAD WHICH GROWS TO A 98 NM SPREAD AT TAU 36. MOREOVER, THE TRACKS SPREAD EVEN FURTHER APART BY TAU 120 TO 172 NM. DUE TO THIS, THE JTWC TRACK IS SET WITH MEDIUM CONFIDENCE OUT TO TAU 72, AND THEN LOW CONFIDENCE OUT TO TAU 120. THE JTWC INTENSITY CONSENSUS MEMBERS ALL AGREE ON AN INTENSIFYING SCENARIO THROUGH TAU 96, THEN A DECREASE AFTERWARDS, BUT ARE SPREAD BY ABOUT 15-20 KNOTS OUT TO TAU 48, AND THEN QUITE SPORADIC AFTERWARDS. THE HIGH RESOLUTION COAMPS-TC AND DECAY SHIPS ARE ON THE LOWER END, WHEREAS GFS AND HWRF ARE ON THE HIGHER END. THE JTWC INTENSITY FORECAST IS SET WITH MEDIUM CONFIDENCE OUT TO TAU 72, AND THEN LOW CONFIDENCE OUT TO TAU 120, FAVORING THE GFS AND HWRF SOLUTIONS.

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