SOUTH PACIFIC: TC 30P(MAILA). WARNING 7 ISSUED BY JTWC @06/1500 UTC
TC WARNING GRAPHICS
PROGNOSTIC REASONING
WDPS31 PGTW 061500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 30P (MAILA) WARNING NR
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 9.7S 155.5E
INITIAL INTENSITY: 95 KTS
GEOGRAPHIC REFERENCE: 712 NM NORTHEAST OF CAIRNS, AUSTRALIA
MOVEMENT PAST 6 HOURS: EASTWARD AT 02 KTS
SIGNIFICANT WAVE HEIGHT: 32 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COMPACT, SYMMETRICAL SYSTEM MEANDERING SLOWLY ABOUT THE NORTHERN
SOLOMON SEA. CONVECTIVE HOT TOWER ACTIVITY HAS DECREASED OVER THE
PAST SIX HOURS, AND THE DEEPEST CONVECTION REMAINS FIRMLY
ENTRENCHED ALONG THE WESTERN THROUGH NORTHERN QUADRANTS OF THE
CIRCULATION. PERSISTENT EASTERLY WIND SHEAR, WITH INDICATIONS OF
HIGHER MID-LEVEL SHEAR, IS KEEPING THE CONVECTION FROM FULLY
WRAPPING UPSHEAR ON THE EASTERN SIDE OF THE CIRCULATION, OR FROM
PERSISTING THERE IF IT DOES MANAGE TO WRAP. WHILE THE EYE IN THE
EIR IS FLEETING AND TRANSIENT, IN THE LOWER LEVELS IT IS VERY
WELL-FORMED AS DEPICTED IN A 060800Z RCM-3 SAR PASS AS WELL AS A
061301Z GMI COLOR-ENHANCED 37GHZ MICROWAVE IMAGE. THE MICROWAVE
IMAGE REVEALS A SOLID WESTERN EYEWALL WITH A MUCH WEAKER EASTERN
EYEWALL. THE SAR DATA REVEALED A VERY SYMMETRICAL EYE OF ABOUT 18NM
IN DIAMETER, WITH A MEAN VMAX OF 92 KNOTS. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE BASED ON AN EXTRAPOLATION BETWEEN THE
GMI MICROWAVE EYE AND THE SAR EYE FEATURE. THE INITIAL INTENSITY IS
ASSESSED WITH HIGH CONFIDENCE BASED ON A BLEND OF THE SUBJECTIVE
AND OBJECTIVE INTENSITY ESTIMATES NOTED BELOW, SUPPORTED BY THE SAR
VMAX DATA. ENVIRONMENTAL CONDITIONS REMAIN OVERALL FAVORABLE,
HOWEVER THE MID-LEVEL SHEAR IS IN THE NEGATIVE COLUMN AND THE
LATEST SST AND OHC ANALYSES INDICATE COOLER WATERS ARE BEGINNING TO
REACH THE SURFACE, A LARGE INHIBITING FACTOR.
INITIAL WIND RADII BASIS: SCATTEROMETER AND SAR DATA.
CURRENT STEERING MECHANISM: COMPETING STEERING PATTERN, WITH STRONG
WEST-NORTHWEST GRADIENT FLOW JUST SOUTH OF EQUATOR AND A DEEP LAYER
SUBTROPICAL RIDGE (STR) OVER NORTHERN AUSTRALIA. THE WESTERLY
GRADIENT FLOW IS CURRENTLY ASSESSED AS SLIGHTLY PREDOMINATE.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T5.5 - 102 KTS
KNES: T6.0 - 115 KTS
ABRF: T5.5 - 102 KTS
CIMSS ADT: 65 KTS AT 061150Z
CIMSS AIDT: 75 KTS AT 061150Z
CIMSS D-MINT: 90 KTS AT 060734Z
CIMSS D-PRINT: 89 KTS AT 061230Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 10-15 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE WESTWARD
OTHER FACTORS: UPWELLING OF COOL OCEANIC WATERS.
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: HIGH
INITIAL WIND RADII: HIGH
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 30P (MAILA) CONTINUES TO
MEANDER SLOWLY EASTWARD, ENSCONCED IN A COMPETING STEERING PATTERN.
FOR THE MOMENT, THE WESTERLY GRADIENT FLOW ALONG THE EQUATOR
APPEARS TO HAVE THE SLIGHT UPPER-HAND AND IS INFLUENCING TC 30P
EASTWARD. OVER THE NEXT 24 TO 36 HOURS, THE GRADIENT IS EXPECTED TO
WEAKEN, ALLOWING TC 30P TO PERFORM A SLOW LOOP NORTH TO THE
NORTH-NORTHWEST. BY TAU 48, RIDGING WILL BUILD IN FROM THE EAST
AFTER PASSAGE OF TC 31P TO THE SOUTH, WHILE SIMULTANEOUSLY THE STR
OVER AUSTRALIA MOVES EASTWARD WHILE BUILDING INTO THE CORAL SEA.
THESE PATTERN CHANGES WILL KICK THE SYSTEM WESTWARD. THROUGH TAU
72, THE STR TO THE SOUTH CONTINUES TO STRENGTHEN AND MOVE EASTWARD,
PUSHING TC 30P ONTO A WEST-SOUTHWEST TRAJECTORY THROUGH THE
REMAINDER OF THE FORECAST PERIOD. THE SYSTEM IS EXPECTED TO CLIP
THE SOUTHEASTERN TIP OF PAPUA NEW GUINEA, PASSING OVER THE EASTERN
APPROACHES TO THE MILNE BAY PRIOR TO TAU 96. THE SYSTEM THEN MOVES
INTO THE NORTHERN CORAL SEA BY TAU 120. REGARDING INTENSITY, A PEAK
INTENSITY OF 100-105 KNOTS IS FORECAST BY TAU 12, BEFORE
SIGNIFICANTLY COOLER WATERS UPWELL TO THE SURFACE AND CUT OFF THE
ENERGY SOURCE FOR THE SYSTEM. A FAIRLY RAPID WEAKENING PHASE BEGINS
IMMEDIATELY AFTER TAU 12, REDUCING THE SYSTEM TO 75 KNOTS OR
POTENTIALLY LOWER BY TAU 48. BY TAU 48, TC 30P WILL BE FAR ENOUGH
AWAY FROM THE UPWELLED COLD POOL TO REINTENSIFY. THE FORECAST CALLS
FOR A SECOND PEAK OF 90 KNOTS, BUT HOW STRONG THE SYSTEM GETS
DURING THIS REINTENSIFICATION PHASE DEPENDS ON HOW WEAK IT GETS
DURING THE WEAKENING PHASE. AS THE SYSTEM APPROACHES MILNE BAY,
DISRUPTION OF THE LOW-LEVEL INFLOW THROUGH TERRAIN INTERACTIONS
WILL SEVERELY DISRUPT THE CORE AND WEAKEN THE SYSTEM AS IT CROSSES
THE PENINSULA. THROUGH THE FINAL HOURS OF THE FORECAST, TC 30P IS
LIKELY TO ATTEMPT ANOTHER ROUND OF INTENSIFICATION BUT DRY AIR
ENTRAINMENT, REDUCED OUTFLOW ALOFT AND MODERATE SHEAR WILL INHIBIT
SIGNIFICANT REINTENSIFICATION.
MODEL DISCUSSION: TRACK GUIDANCE CONTINUES TO IMPROVE IN TERMS OF
OVERALL AGREEMENT WITH THE TRACK SCENARIO. THROUGH TAU 48, THE
CONSENSUS PACKAGE, WITH THE EXCEPTION OF THE AI MODELS AND THE
NAVGEM, AGREE ON A EASTWARD TRACK WHICH TURNS SLOWLY BUT SHARPLY IN
A COUNTER-CLOCKWISE LOOP. WITH THE EXCEPTIONS NOTED ABOVE, THE
REMAINDER OF THE GUIDANCE IS VERY TIGHTLY PACKED, LENDING MEDIUM TO
HIGH CONFIDENCE THROUGH THIS POINT IN THE FORECAST. BY TAU 72, THE
PREVIOUSLY MENTIONED OUTLIERS BEGIN TO MAKE AN ATTEMPT TO REJOIN
THE PACK BUT ARE STILL OUTLIERS TO THE NORTH. THE REMAINDER OF THE
PACKAGE IS STILL TIGHTLY CONSTRAINED IN A 60NM WIDE ENVELOPE THAT
PRESENTING A SOUTHWESTWARD TRAJECTORY. ALONG-TRACK SPREAD BEGINS TO
INCREASE BY TAU 72, WITH THE ECWMF BEING THE FASTEST MODEL AND THE
NAVGEM THE SLOWEST. BY TAU 120, CROSS-TRACK SPREAD INCREASES TO
ABOUT 200NM, BETWEEN THE FNV3 ON THE NORTH SIDE AND NAVGEM ON THE
SOUTH SIDE OF THE ENVELOPE. MORE SIGNIFICANT IS THE INCREASING
ALONG-TRACK SPREAD, WHICH INCREASES TO MORE THAN 300NM BY TAU 120
WITH ECMWF CONTINUING TO OUTPACE ALL THE OTHER MODELS. THE AI
MODELS (AICN AND EC-AIFS IN PARTICULAR) ARE SIGNIFICANT OUTLIERS IN
THE EXTENDED FORECAST, TRACKING THE SYSTEM FURTHER EQUATORWARD
THROUGH THE END OF THE FORECAST. THE JTWC FORECAST IS PLACED NEAR,
AND SLIGHTLY FASTER, THAN THE CONSENSUS MEAN FROM TAU 72 TO 120,
WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS SPLIT INTO TWO CAMPS,
THE COUPLED AND THE UNCOUPLED MODELS. IN THIS FORECAST, THE COUPLED
MODELS HAVE THE UPPER-HAND, AND INDICATE A FLAT INTENSITY THROUGH
TAU 12, THEN RAPID WEAKENING, BOTTOMING OUT BETWEEN 70-75 KNOTS BY
TAU 36 BEFORE RAPIDLY RECOVERING AND REINTENSIFYING TO A PEAK
BETWEEN 85-95 KNOTS BY TAU 72. THEREAFTER THE TWO CAMPS REJOIN AND
AGREE ON A SLOW WEAKENING TREND THROUGH TAU 120. THE JTWC FORECAST
IS PLACED NEAR THE HAFS-A GUIDANCE, ESPECIALLY AFTER TAU 24.
FORECAST CONFIDENCE:
TRACK 00-72 HR: MEDIUM
TRACK 72-120 HR: MEDIUM
INTENSITY 00-72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
NNNN
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 30P (MAILA) WARNING NR
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 9.7S 155.5E
INITIAL INTENSITY: 95 KTS
GEOGRAPHIC REFERENCE: 712 NM NORTHEAST OF CAIRNS, AUSTRALIA
MOVEMENT PAST 6 HOURS: EASTWARD AT 02 KTS
SIGNIFICANT WAVE HEIGHT: 32 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COMPACT, SYMMETRICAL SYSTEM MEANDERING SLOWLY ABOUT THE NORTHERN
SOLOMON SEA. CONVECTIVE HOT TOWER ACTIVITY HAS DECREASED OVER THE
PAST SIX HOURS, AND THE DEEPEST CONVECTION REMAINS FIRMLY
ENTRENCHED ALONG THE WESTERN THROUGH NORTHERN QUADRANTS OF THE
CIRCULATION. PERSISTENT EASTERLY WIND SHEAR, WITH INDICATIONS OF
HIGHER MID-LEVEL SHEAR, IS KEEPING THE CONVECTION FROM FULLY
WRAPPING UPSHEAR ON THE EASTERN SIDE OF THE CIRCULATION, OR FROM
PERSISTING THERE IF IT DOES MANAGE TO WRAP. WHILE THE EYE IN THE
EIR IS FLEETING AND TRANSIENT, IN THE LOWER LEVELS IT IS VERY
WELL-FORMED AS DEPICTED IN A 060800Z RCM-3 SAR PASS AS WELL AS A
061301Z GMI COLOR-ENHANCED 37GHZ MICROWAVE IMAGE. THE MICROWAVE
IMAGE REVEALS A SOLID WESTERN EYEWALL WITH A MUCH WEAKER EASTERN
EYEWALL. THE SAR DATA REVEALED A VERY SYMMETRICAL EYE OF ABOUT 18NM
IN DIAMETER, WITH A MEAN VMAX OF 92 KNOTS. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE BASED ON AN EXTRAPOLATION BETWEEN THE
GMI MICROWAVE EYE AND THE SAR EYE FEATURE. THE INITIAL INTENSITY IS
ASSESSED WITH HIGH CONFIDENCE BASED ON A BLEND OF THE SUBJECTIVE
AND OBJECTIVE INTENSITY ESTIMATES NOTED BELOW, SUPPORTED BY THE SAR
VMAX DATA. ENVIRONMENTAL CONDITIONS REMAIN OVERALL FAVORABLE,
HOWEVER THE MID-LEVEL SHEAR IS IN THE NEGATIVE COLUMN AND THE
LATEST SST AND OHC ANALYSES INDICATE COOLER WATERS ARE BEGINNING TO
REACH THE SURFACE, A LARGE INHIBITING FACTOR.
INITIAL WIND RADII BASIS: SCATTEROMETER AND SAR DATA.
CURRENT STEERING MECHANISM: COMPETING STEERING PATTERN, WITH STRONG
WEST-NORTHWEST GRADIENT FLOW JUST SOUTH OF EQUATOR AND A DEEP LAYER
SUBTROPICAL RIDGE (STR) OVER NORTHERN AUSTRALIA. THE WESTERLY
GRADIENT FLOW IS CURRENTLY ASSESSED AS SLIGHTLY PREDOMINATE.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T5.5 - 102 KTS
KNES: T6.0 - 115 KTS
ABRF: T5.5 - 102 KTS
CIMSS ADT: 65 KTS AT 061150Z
CIMSS AIDT: 75 KTS AT 061150Z
CIMSS D-MINT: 90 KTS AT 060734Z
CIMSS D-PRINT: 89 KTS AT 061230Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 10-15 KTS
SST: 29-30 CELSIUS
OUTFLOW: MODERATE WESTWARD
OTHER FACTORS: UPWELLING OF COOL OCEANIC WATERS.
ANALYSIS CONFIDENCE:
INITIAL POSITION: HIGH
INITIAL INTENSITY: HIGH
INITIAL WIND RADII: HIGH
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 30P (MAILA) CONTINUES TO
MEANDER SLOWLY EASTWARD, ENSCONCED IN A COMPETING STEERING PATTERN.
FOR THE MOMENT, THE WESTERLY GRADIENT FLOW ALONG THE EQUATOR
APPEARS TO HAVE THE SLIGHT UPPER-HAND AND IS INFLUENCING TC 30P
EASTWARD. OVER THE NEXT 24 TO 36 HOURS, THE GRADIENT IS EXPECTED TO
WEAKEN, ALLOWING TC 30P TO PERFORM A SLOW LOOP NORTH TO THE
NORTH-NORTHWEST. BY TAU 48, RIDGING WILL BUILD IN FROM THE EAST
AFTER PASSAGE OF TC 31P TO THE SOUTH, WHILE SIMULTANEOUSLY THE STR
OVER AUSTRALIA MOVES EASTWARD WHILE BUILDING INTO THE CORAL SEA.
THESE PATTERN CHANGES WILL KICK THE SYSTEM WESTWARD. THROUGH TAU
72, THE STR TO THE SOUTH CONTINUES TO STRENGTHEN AND MOVE EASTWARD,
PUSHING TC 30P ONTO A WEST-SOUTHWEST TRAJECTORY THROUGH THE
REMAINDER OF THE FORECAST PERIOD. THE SYSTEM IS EXPECTED TO CLIP
THE SOUTHEASTERN TIP OF PAPUA NEW GUINEA, PASSING OVER THE EASTERN
APPROACHES TO THE MILNE BAY PRIOR TO TAU 96. THE SYSTEM THEN MOVES
INTO THE NORTHERN CORAL SEA BY TAU 120. REGARDING INTENSITY, A PEAK
INTENSITY OF 100-105 KNOTS IS FORECAST BY TAU 12, BEFORE
SIGNIFICANTLY COOLER WATERS UPWELL TO THE SURFACE AND CUT OFF THE
ENERGY SOURCE FOR THE SYSTEM. A FAIRLY RAPID WEAKENING PHASE BEGINS
IMMEDIATELY AFTER TAU 12, REDUCING THE SYSTEM TO 75 KNOTS OR
POTENTIALLY LOWER BY TAU 48. BY TAU 48, TC 30P WILL BE FAR ENOUGH
AWAY FROM THE UPWELLED COLD POOL TO REINTENSIFY. THE FORECAST CALLS
FOR A SECOND PEAK OF 90 KNOTS, BUT HOW STRONG THE SYSTEM GETS
DURING THIS REINTENSIFICATION PHASE DEPENDS ON HOW WEAK IT GETS
DURING THE WEAKENING PHASE. AS THE SYSTEM APPROACHES MILNE BAY,
DISRUPTION OF THE LOW-LEVEL INFLOW THROUGH TERRAIN INTERACTIONS
WILL SEVERELY DISRUPT THE CORE AND WEAKEN THE SYSTEM AS IT CROSSES
THE PENINSULA. THROUGH THE FINAL HOURS OF THE FORECAST, TC 30P IS
LIKELY TO ATTEMPT ANOTHER ROUND OF INTENSIFICATION BUT DRY AIR
ENTRAINMENT, REDUCED OUTFLOW ALOFT AND MODERATE SHEAR WILL INHIBIT
SIGNIFICANT REINTENSIFICATION.
MODEL DISCUSSION: TRACK GUIDANCE CONTINUES TO IMPROVE IN TERMS OF
OVERALL AGREEMENT WITH THE TRACK SCENARIO. THROUGH TAU 48, THE
CONSENSUS PACKAGE, WITH THE EXCEPTION OF THE AI MODELS AND THE
NAVGEM, AGREE ON A EASTWARD TRACK WHICH TURNS SLOWLY BUT SHARPLY IN
A COUNTER-CLOCKWISE LOOP. WITH THE EXCEPTIONS NOTED ABOVE, THE
REMAINDER OF THE GUIDANCE IS VERY TIGHTLY PACKED, LENDING MEDIUM TO
HIGH CONFIDENCE THROUGH THIS POINT IN THE FORECAST. BY TAU 72, THE
PREVIOUSLY MENTIONED OUTLIERS BEGIN TO MAKE AN ATTEMPT TO REJOIN
THE PACK BUT ARE STILL OUTLIERS TO THE NORTH. THE REMAINDER OF THE
PACKAGE IS STILL TIGHTLY CONSTRAINED IN A 60NM WIDE ENVELOPE THAT
PRESENTING A SOUTHWESTWARD TRAJECTORY. ALONG-TRACK SPREAD BEGINS TO
INCREASE BY TAU 72, WITH THE ECWMF BEING THE FASTEST MODEL AND THE
NAVGEM THE SLOWEST. BY TAU 120, CROSS-TRACK SPREAD INCREASES TO
ABOUT 200NM, BETWEEN THE FNV3 ON THE NORTH SIDE AND NAVGEM ON THE
SOUTH SIDE OF THE ENVELOPE. MORE SIGNIFICANT IS THE INCREASING
ALONG-TRACK SPREAD, WHICH INCREASES TO MORE THAN 300NM BY TAU 120
WITH ECMWF CONTINUING TO OUTPACE ALL THE OTHER MODELS. THE AI
MODELS (AICN AND EC-AIFS IN PARTICULAR) ARE SIGNIFICANT OUTLIERS IN
THE EXTENDED FORECAST, TRACKING THE SYSTEM FURTHER EQUATORWARD
THROUGH THE END OF THE FORECAST. THE JTWC FORECAST IS PLACED NEAR,
AND SLIGHTLY FASTER, THAN THE CONSENSUS MEAN FROM TAU 72 TO 120,
WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS SPLIT INTO TWO CAMPS,
THE COUPLED AND THE UNCOUPLED MODELS. IN THIS FORECAST, THE COUPLED
MODELS HAVE THE UPPER-HAND, AND INDICATE A FLAT INTENSITY THROUGH
TAU 12, THEN RAPID WEAKENING, BOTTOMING OUT BETWEEN 70-75 KNOTS BY
TAU 36 BEFORE RAPIDLY RECOVERING AND REINTENSIFYING TO A PEAK
BETWEEN 85-95 KNOTS BY TAU 72. THEREAFTER THE TWO CAMPS REJOIN AND
AGREE ON A SLOW WEAKENING TREND THROUGH TAU 120. THE JTWC FORECAST
IS PLACED NEAR THE HAFS-A GUIDANCE, ESPECIALLY AFTER TAU 24.
FORECAST CONFIDENCE:
TRACK 00-72 HR: MEDIUM
TRACK 72-120 HR: MEDIUM
INTENSITY 00-72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
NNNN
RIPA FORECAST
Platform: RCM-1
Acquisition Date: 2026-04-06 08:00:39 UTC
Storm Name: SH302026 / MAILA
Storm ID: SH30
Storm Center Longitude: 155.493
Storm Center Latitude: -9.700
Incidence Angle (Degrees): 39.378
Quadrant 1 NE VMax (kts): 101.83
Quadrant 2 SE VMax (kts): 83.30
Quadrant 3 SW VMax (kts): 87.06
Quadrant 4 NW VMax (kts): 97.78
RMax (nmi): 17.00 - 23.00
Acquisition Date: 2026-04-06 08:00:39 UTC
Storm Name: SH302026 / MAILA
Storm ID: SH30
Storm Center Longitude: 155.493
Storm Center Latitude: -9.700
Incidence Angle (Degrees): 39.378
Quadrant 1 NE VMax (kts): 101.83
Quadrant 2 SE VMax (kts): 83.30
Quadrant 3 SW VMax (kts): 87.06
Quadrant 4 NW VMax (kts): 97.78
RMax (nmi): 17.00 - 23.00
SOUTH PACIFIC : TC 31P (VAIANU). WARNING 5 ISSUED BY JTWC @06/1500 UTC
TC WARNING GRAPHICS
PROGNOSTIC REASONING
WDPS32 PGTW 061500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 31P (VAIANU) WARNING
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 16.5S 173.8E
INITIAL INTENSITY: 95 KTS
GEOGRAPHIC REFERENCE: 280 NM WEST-NORTHWEST OF SUVA, FIJI
MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 08 KTS
SIGNIFICANT WAVE HEIGHT: 32 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COMPACT SYSTEM, WITH A SYMMETRICAL BALL OF DEEP CONVECTION ARRAYED
AROUND A NASCENT PINHOLE EYE. THE STRONGEST OF THE CONVECTION IS
ARRAYED ACROSS THE SOUTHERN SEMICIRCLE OF THE CIRCULATION,
CONSISTENT WITH THE 10-15 KNOTS OF SHEAR COMING DOWN ON THE SYSTEM
FROM THE NORTH. VORTICAL HOT TOWERS (VHTS) CAN BE SEEN DEVELOPING
ALONG THE SOUTHERN FLANK OF THE NASCENT EYE FEATURE, WHICH HAS BEEN
A PERSISTENT FEATURE FOR THE PAST SIX HOURS, BUT DUE TO THE
PERSISTENT NORTHERLY SHEAR, THEY ARE FAILING TO WRAP UPSHEAR AND
THUS THE EYE HAS BEEN UNSUCCESSFUL IN FULLY EMERGING. A 061125Z GMI
COLOR-ENHANCED 37GHZ IMAGE REVEALED A WELL-FORMED, HIGHLY
SYMMETRICAL MICROWAVE EYE, WITH STRONG CONVECTION ON THE
SOUTHEASTERN AND SOUTHERN FLANKS, WHILE ONLY WEAK CONVECTION IS
PRESENT IN THE NORTHWESTERN QUADRANT. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE USING THE MICROWAVE EYE FEATURE IN
THE GMI PASS. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE USING A BLEND OF THE AGENCY INTENSITY ESTIMATES, ALONG
WITH PERSISTENCE WITH AN EARLIER SAR PASS. ENVIRONMENTAL CONDITIONS
REMAIN FAVORABLE IN GENERAL, WITH LOW DEEP-LAYER SHEAR, WARM SSTS
AND VIGOROUS POLEWARD OUTFLOW.
INITIAL WIND RADII BASIS: SCATTEROMETER AND SAR DATA.
CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED NEAR SAMOA.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T5.0 - 90 KTS
KNES: T5.5 - 102 KTS
PHFO: T5.5 - 102 KTS
CIMSS ADT: 79 KTS AT 061200Z
CIMSS AIDT: 79 KTS AT 061200Z
CIMSS D-PRINT: 88 KTS AT 061200Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 5-10 KTS
SST: 29-30 CELSIUS
OUTFLOW: STRONG POLEWARD
OTHER FACTORS: MODERATE MID-LEVEL NORTHERLY SHEAR.
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: TROPICAL CYCLONE (TC) 31P (VAIANU) APPEARS TO
HAVE FINALLY ACHIEVED VORTEX ALIGNMENT, AND AFTER A PERIOD OF
RELATIVELY SLOW FORWARD SPEED, HAS BEGUN TO ACCELERATE
SOUTHEASTWARD. A STRAIGHT SOUTHEASTWARD TRACK, ALONG THE WESTERN
FLANK OF THE DEEP STR NEAR SAMOA, IS FORECAST FOR THE NEXT 72
HOURS. BY TAU 72, TC 31P PASSES UNDER THE AXIS OF A STRENGTHENING
SUBTROPICAL JET MAX AND BEGINS TO BE BOTH PULLED IN TOWARDS A 200MB
TROUGH, WHILE SIMULTANEOUSLY BEING PUSHED SOUTHWESTWARD ALONG THE
WESTERN SIDE OF A RAPIDLY BUILDING RIDGE TO THE EAST WHICH BUILDS
POLEWARD TO 40S. BY THE END OF THE FORECAST, TC 31P WILL BE
TRACKING SOUTHWESTWARD TOWARDS THE NORTH ISLAND OF NEW ZEALAND.
REGARDING INTENSITY, THE SYSTEM HAS ANOTHER 24 HOURS WORTH OF
FAVORABLE CONDITIONS TO INTENSIFY BEFORE WIND SHEAR INCREASES
SHARPLY. ANTICIPATING AN EYE TO DEVELOP IN THE NEAR-TERM, THE
FORECAST CALLS FOR THE SYSTEM TO INTENSIFY TO A PEAK OF 105 KNOTS
WITHIN THE NEXT 12 TO 24 HOURS, THEN BEGIN TO RAPIDLY WEAKEN UNDER
THE INFLUENCE OF HIGH NORTHWESTERLY SHEAR. THE SYSTEM CROSSES THE
26C ISOTHERM AROUND TAU 60. ONCE THE SYSTEM CROSSES THE AXIS OF THE
SUBTROPICAL JET, IT MOVES INTO THE EQUATORWARD SIDE (UNDER AN
UPPER-LEVEL TROUGH OR LOW) OF A LARGE REX BLOCK THAT DEVELOPS
BETWEEN FIJI AND NEW ZEALAND. AT THIS POINT, SSTS WILL BE IN THE
22-24C RANGE. HOWEVER, ALL GLOBAL MODELS INDICATE THE SYSTEM WILL
RETAIN ITS WARM CORE AND REMAIN RELATIVELY MOIST THROUGH A DEEP
LAYER OF THE ATMOSPHERE, THOUGH UNDER A COLD 200MB LOW, THE
FORECAST CALLS FOR EXTRATROPICAL TRANSITION (ETT) BEGINNING AT TAU
72, COMPLETING BY THE END OF THE FORECAST. HOWEVER, A MORE ACCURATE
DESCRIPTION WOULD BE TO CALL THE REMNANTS OF TC 31P A HYBRID WARM
CORE CYCLONE. UNDER FAVORABLE, LOW SHEAR CONDITIONS AND WITH A WARM
LOW- TO MID-LEVEL VORTEX UNDER A COLD LOW ALOFT, THE SYSTEM COULD
IN FACT REINTENSIFY OR AT LEAST MAINTAIN INTENSITY AS IT UNDERGOES
TRANSITION TO A HYBRID CYCLONE.
MODEL DISCUSSION: TRACK GUIDANCE IS IN STRONG AGREEMENT THROUGH TAU
72, WITH MINIMAL (LESS THAN 75NM) CROSS-TRACK SPREAD THROUGH THIS
POINT IN THE FORECAST. ALONG-TRACK SPREAD REMAINS A PERSISTENT
ISSUE EVEN AS EARLY AS TAU 48, WITH THE FASTEST AI MODELS OPENING
UP A LEAD OVER THE EGRR AND GALWEM OF 200NM BY TAU 72. AS THE
SYSTEM TURNS SOUTHWESTWARD, CROSS-TRACK SPREAD INCREASES TO 315NM,
BETWEEN THE EGRR-GALWEM PAIR ON THE WEST EDGE AND THE AI MODEL
GROUPING ON THE EASTERN EDGE OF THE ENVELOPE, WHILE ALONG-TRACK
SPREAD DECREASES TO BASICALLY ZERO. THE JTWC FORECAST IS PLACED
NEAR THE CONSENSUS MEAN THROUGH THE ENTIRE FORECAST PERIOD, WITH
HIGH CONFIDENCE THROUGH TAU 72 AND MEDIUM CONFIDENCE THROUGH TAU
120. INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT, WITH ALL MODELS
EXCEPT THE HWRF INDICATING ABOUT 5-15 KNOTS OF INTENSIFICATION
THROUGH TAU 24 THEN SHARP WEAKENING THROUGH TAU 72. MOST OF THE
GUIDANCE DEPICTS EITHER SLOW WEAKENING OR STEADY INTENSITY FROM
TAU 84 TO 120. THE JTWC FORECAST IS PLACED NEAR THE HAFS-A GUIDANCE
WITH MEDIUM CONFIDENCE.
FORECAST CONFIDENCE:
TRACK 00-72 HR: HIGH
TRACK 72-120 HR: MEDIUM
INTENSITY 00-72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
NNNN
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 31P (VAIANU) WARNING
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 16.5S 173.8E
INITIAL INTENSITY: 95 KTS
GEOGRAPHIC REFERENCE: 280 NM WEST-NORTHWEST OF SUVA, FIJI
MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 08 KTS
SIGNIFICANT WAVE HEIGHT: 32 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COMPACT SYSTEM, WITH A SYMMETRICAL BALL OF DEEP CONVECTION ARRAYED
AROUND A NASCENT PINHOLE EYE. THE STRONGEST OF THE CONVECTION IS
ARRAYED ACROSS THE SOUTHERN SEMICIRCLE OF THE CIRCULATION,
CONSISTENT WITH THE 10-15 KNOTS OF SHEAR COMING DOWN ON THE SYSTEM
FROM THE NORTH. VORTICAL HOT TOWERS (VHTS) CAN BE SEEN DEVELOPING
ALONG THE SOUTHERN FLANK OF THE NASCENT EYE FEATURE, WHICH HAS BEEN
A PERSISTENT FEATURE FOR THE PAST SIX HOURS, BUT DUE TO THE
PERSISTENT NORTHERLY SHEAR, THEY ARE FAILING TO WRAP UPSHEAR AND
THUS THE EYE HAS BEEN UNSUCCESSFUL IN FULLY EMERGING. A 061125Z GMI
COLOR-ENHANCED 37GHZ IMAGE REVEALED A WELL-FORMED, HIGHLY
SYMMETRICAL MICROWAVE EYE, WITH STRONG CONVECTION ON THE
SOUTHEASTERN AND SOUTHERN FLANKS, WHILE ONLY WEAK CONVECTION IS
PRESENT IN THE NORTHWESTERN QUADRANT. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE USING THE MICROWAVE EYE FEATURE IN
THE GMI PASS. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE USING A BLEND OF THE AGENCY INTENSITY ESTIMATES, ALONG
WITH PERSISTENCE WITH AN EARLIER SAR PASS. ENVIRONMENTAL CONDITIONS
REMAIN FAVORABLE IN GENERAL, WITH LOW DEEP-LAYER SHEAR, WARM SSTS
AND VIGOROUS POLEWARD OUTFLOW.
INITIAL WIND RADII BASIS: SCATTEROMETER AND SAR DATA.
CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED NEAR SAMOA.
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T5.0 - 90 KTS
KNES: T5.5 - 102 KTS
PHFO: T5.5 - 102 KTS
CIMSS ADT: 79 KTS AT 061200Z
CIMSS AIDT: 79 KTS AT 061200Z
CIMSS D-PRINT: 88 KTS AT 061200Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
VWS: 5-10 KTS
SST: 29-30 CELSIUS
OUTFLOW: STRONG POLEWARD
OTHER FACTORS: MODERATE MID-LEVEL NORTHERLY SHEAR.
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: TROPICAL CYCLONE (TC) 31P (VAIANU) APPEARS TO
HAVE FINALLY ACHIEVED VORTEX ALIGNMENT, AND AFTER A PERIOD OF
RELATIVELY SLOW FORWARD SPEED, HAS BEGUN TO ACCELERATE
SOUTHEASTWARD. A STRAIGHT SOUTHEASTWARD TRACK, ALONG THE WESTERN
FLANK OF THE DEEP STR NEAR SAMOA, IS FORECAST FOR THE NEXT 72
HOURS. BY TAU 72, TC 31P PASSES UNDER THE AXIS OF A STRENGTHENING
SUBTROPICAL JET MAX AND BEGINS TO BE BOTH PULLED IN TOWARDS A 200MB
TROUGH, WHILE SIMULTANEOUSLY BEING PUSHED SOUTHWESTWARD ALONG THE
WESTERN SIDE OF A RAPIDLY BUILDING RIDGE TO THE EAST WHICH BUILDS
POLEWARD TO 40S. BY THE END OF THE FORECAST, TC 31P WILL BE
TRACKING SOUTHWESTWARD TOWARDS THE NORTH ISLAND OF NEW ZEALAND.
REGARDING INTENSITY, THE SYSTEM HAS ANOTHER 24 HOURS WORTH OF
FAVORABLE CONDITIONS TO INTENSIFY BEFORE WIND SHEAR INCREASES
SHARPLY. ANTICIPATING AN EYE TO DEVELOP IN THE NEAR-TERM, THE
FORECAST CALLS FOR THE SYSTEM TO INTENSIFY TO A PEAK OF 105 KNOTS
WITHIN THE NEXT 12 TO 24 HOURS, THEN BEGIN TO RAPIDLY WEAKEN UNDER
THE INFLUENCE OF HIGH NORTHWESTERLY SHEAR. THE SYSTEM CROSSES THE
26C ISOTHERM AROUND TAU 60. ONCE THE SYSTEM CROSSES THE AXIS OF THE
SUBTROPICAL JET, IT MOVES INTO THE EQUATORWARD SIDE (UNDER AN
UPPER-LEVEL TROUGH OR LOW) OF A LARGE REX BLOCK THAT DEVELOPS
BETWEEN FIJI AND NEW ZEALAND. AT THIS POINT, SSTS WILL BE IN THE
22-24C RANGE. HOWEVER, ALL GLOBAL MODELS INDICATE THE SYSTEM WILL
RETAIN ITS WARM CORE AND REMAIN RELATIVELY MOIST THROUGH A DEEP
LAYER OF THE ATMOSPHERE, THOUGH UNDER A COLD 200MB LOW, THE
FORECAST CALLS FOR EXTRATROPICAL TRANSITION (ETT) BEGINNING AT TAU
72, COMPLETING BY THE END OF THE FORECAST. HOWEVER, A MORE ACCURATE
DESCRIPTION WOULD BE TO CALL THE REMNANTS OF TC 31P A HYBRID WARM
CORE CYCLONE. UNDER FAVORABLE, LOW SHEAR CONDITIONS AND WITH A WARM
LOW- TO MID-LEVEL VORTEX UNDER A COLD LOW ALOFT, THE SYSTEM COULD
IN FACT REINTENSIFY OR AT LEAST MAINTAIN INTENSITY AS IT UNDERGOES
TRANSITION TO A HYBRID CYCLONE.
MODEL DISCUSSION: TRACK GUIDANCE IS IN STRONG AGREEMENT THROUGH TAU
72, WITH MINIMAL (LESS THAN 75NM) CROSS-TRACK SPREAD THROUGH THIS
POINT IN THE FORECAST. ALONG-TRACK SPREAD REMAINS A PERSISTENT
ISSUE EVEN AS EARLY AS TAU 48, WITH THE FASTEST AI MODELS OPENING
UP A LEAD OVER THE EGRR AND GALWEM OF 200NM BY TAU 72. AS THE
SYSTEM TURNS SOUTHWESTWARD, CROSS-TRACK SPREAD INCREASES TO 315NM,
BETWEEN THE EGRR-GALWEM PAIR ON THE WEST EDGE AND THE AI MODEL
GROUPING ON THE EASTERN EDGE OF THE ENVELOPE, WHILE ALONG-TRACK
SPREAD DECREASES TO BASICALLY ZERO. THE JTWC FORECAST IS PLACED
NEAR THE CONSENSUS MEAN THROUGH THE ENTIRE FORECAST PERIOD, WITH
HIGH CONFIDENCE THROUGH TAU 72 AND MEDIUM CONFIDENCE THROUGH TAU
120. INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT, WITH ALL MODELS
EXCEPT THE HWRF INDICATING ABOUT 5-15 KNOTS OF INTENSIFICATION
THROUGH TAU 24 THEN SHARP WEAKENING THROUGH TAU 72. MOST OF THE
GUIDANCE DEPICTS EITHER SLOW WEAKENING OR STEADY INTENSITY FROM
TAU 84 TO 120. THE JTWC FORECAST IS PLACED NEAR THE HAFS-A GUIDANCE
WITH MEDIUM CONFIDENCE.
FORECAST CONFIDENCE:
TRACK 00-72 HR: HIGH
TRACK 72-120 HR: MEDIUM
INTENSITY 00-72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
NNNN
