WPAC: 96W - Post Tropical

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WDPN32 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 06W (SIX) WARNING NR
011//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 06W (SIX), LOCATED APPROXIMATELY 473 NM EAST
OF KADENA AB, OKINAWA, HAS TRACKED WEST-SOUTHWESTWARD AT 10 KNOTS (KTS)
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
REVEALS POCKETS OF CONVECTION OBSCURING A WELL-DEFINED LOW LEVEL
CIRCULATION CENTER (LLCC), LENDING GOOD CONFIDENCE TO THE INITIAL
POSITION. A 120102Z ASCAT-B IMAGE DEPICTS A SWATH OF 25-29 KT WIND BARBS
TO THE NORTH OF THE LLCC WITH WEAKER WINDS TO THE EAST AND SOUTH.
THEREFORE, THE INITIAL INTENSITY OF 25 KTS IS BASED ON THE
AFOREMENTIONED ASCAT AND DVORAK CURRENT INTENSITY ESTIMATES OF T1.5 (25
KTS) BY PGTW/RJTD WITH GOOD CONFIDENCE. PERSISTENT EASTERLY VERTICAL
WIND SHEAR (VWS) AND DRY AIR ENTRAINMENT SEEN IN TOTAL PRECIPITABLE
WATER IMAGERY OFFSET THE WARM (NEAR 30 CELSIUS) SEA SURFACE TEMPERATURES
AND EQUATORWARD OUTFLOW, PLACING TD 06W IN A MARGINALLY FAVORABLE
ENVIRONMENT. ADDITIONALLY, LOW 700-500MB RELATIVE HUMIDITY VALUES OF 40-
45% ARE CAUSING THE SYSTEM TO STRUGGLE. TD 06W IS TRACKING WEST-
SOUTHWESTWARD UNDER THE STEERING INFLUENCE OF A LOW LEVEL SUBTROPICAL
RIDGE (STR) ORIENTED WSW-ENE.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC
REASONING MESSAGE.
B. DUE TO THE WSW-ENE ORIENTATION OF THE LOW-LEVEL STR, TD 06W IS
EXPECTED TO TRACK WEST-SOUTHWESTWARD THROUGH TAU 12 THEN TURN WESTWARD
AS IT APPROACHES THE RYUKYU ISLANDS. BY TAU 36, THE SYSTEM WILL SHIFT TO
A WEST-NORTHWESTWARD TRACK FOR THE REMAINDER OF THE FORECAST PERIOD.
OVERALL, TD 06W IS FORECAST TO TRANSIT THROUGH A MARGINALLY FAVORABLE
ENVIRONMENT OF LOW TO MODERATE EAST-NORTHEASTERLY VWS. COMBINED WITH
CONTINUED DRY AIR ENTRAINMENT AND LOW RELATIVE HUMIDITY VALUES, TD 06W
SHOULD REMAIN SHALLOW AND RELATIVELY WEAK WITH DISSIPATION EXPECTED BY
TAU 72, IF NOT SOONER. NUMERICAL MODELS REMAIN IN FAIR AGREEMENT WITH
CROSS-TRACK SPREAD INCREASING IN THE LATER TAUS AS THE SYSTEM
DISSIPATES. THE GFS ENSEMBLE REMAINS THE OUTLIER TO THE SOUTH AND IS
OFFSET BY THE NORTHERLY OUTLIER, NAVGEM. THUS, THE JTWC FORECAST TRACK
IS PLACED ALONG THE MULTI-MODEL CONSENSUS WITH MODERATE CONFIDENCE.//
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WDPN32 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 06W (SIX) WARNING
NR 012//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 06W (SIX), LOCATED APPROXIMATELY 411 NM
EAST OF KADENA AB, OKINAWA, HAS TRACKED WEST-SOUTHWESTWARD AT 11
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS EXPOSED LOW-LEVEL CLOUD LINES WRAPPING INTO A BROAD,
RAGGED CENTER. A 120646Z SSMIS 91GHZ MICROWAVE IMAGE SHOWS ISOLATED
CONVECTIVE BURSTS OVER THE WEST AND SOUTHWEST QUADRANTS BUT OVERALL
WEAK CONVECTIVE STRUCTURE. RECENT ASCAT IMAGERY AND THE SSMIS WIND
PRODUCT INDICATE A HIGHLY ASYMMETRIC WIND FIELD WITH A PATCH OF 20-
25 KNOT WINDS OVER THE NORTHWEST QUADRANT AND A BROADENING CENTER
REFLECTING A GRADUAL WEAKENING TREND. HOWEVER, THE INITIAL INTENSITY
IS HELD AT 25 KNOTS BASED ON THE ASCAT DATA AND DVORAK CURRENT
INTENSITY ESTIMATES OF 1.0-1.5 (25 KNOTS). THE SYSTEM REMAINS
EMBEDDED WITHIN AN EXPANSIVE REGION OF ENHANCED EASTERLIES BETWEEN
THE UPPER-LEVEL RIDGE AND A TUTT CELL TO THE SOUTHEAST WITH LOW TO
MODERATE (15 TO 20 KNOTS) VERTICAL WIND SHEAR, DRY AIR ENTRAINMENT
AND WEAK DIFFLUENCE. TD 06W IS TRACKING WEST-SOUTHWESTWARD UNDER THE
STEERING INFLUENCE OF A LOW-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED
TO THE NORTH AND NORTHWEST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. DUE TO THE WSW-ENE ORIENTATION OF THE LOW-LEVEL STR, TD 06W IS
FORECAST TO CONTINUE TRACKING WEST-SOUTHWESTWARD THROUGH TAU 24. AS
IT APPROACHES THE RYUKYU ISLANDS, THE SYSTEM SHOULD TURN WESTWARD TO
WEST-NORTHWESTWARD AS IT TRACKS ALONG THE SOUTHWEST PERIPHERY OF THE
STR. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN MARGINAL WITH
LOW TO MODERATE VWS AND DRY AIR ENTRAINMENT (700-500MB RH VALUES OF
50-55%), THEREFORE, THE SYSTEM SHOULD REMAIN SHALLOW AND WEAK WITH
SOME POTENTIAL FOR DISSIPATION DURING THE FORECAST PERIOD. NUMERICAL
MODEL GUIDANCE SUPPORTS THE JTWC FORECAST TRACK AND REMAINS IN FAIR
AGREEMENT WITH MINOR VARIATIONS IN TRACK ORIENTATION THROUGH TAU 48.
MODEL SPREAD AT TAU 36 TO 48 RANGES FROM 50 TO 110NM, THEREFORE, THE
JTWC FORECAST TRACK IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS
WITH MODERATE CONFIDENCE.//
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A struggling TD in August. I wonder when was the last time we saw something like this recently?

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WDPN32 PGTW 122100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 06W (SIX) WARNING
NR 014//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 06W (SIX), LOCATED APPROXIMATELY 299 NM
EAST-SOUTHEAST OF KADENA AB, OKINAWA, JAPAN HAS TRACKED WEST-
SOUTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY DEPICTS DEEP CONVECTION BUILDING OVER THE
LOW-LEVEL CIRCULATION (LLC), OBSCURING THE EXACT LOCATION OF THE
LLC. THERE ARE NO RECENT MICROWAVE IMAGES AVAILABLE TO ASSIST IN
DETERMINING THE EXACT LOCATION OF THE LLC, LEADING TO LOW CONFIDENCE
IN THE INITIAL POSITION. THE INITIAL INTENSITY IS HELD AT 25 KNOTS
BASED ON A PGTW DVORAK CURRENT INTENSITY ESTIMATE OF 1.5 (25 KNOTS).
THE SYSTEM REMAINS EMBEDDED WITHIN AN EXPANSIVE REGION OF ENHANCED
EASTERLIES BETWEEN THE UPPER-LEVEL RIDGE AND A TUTT CELL TO THE
SOUTHEAST WITH LOW TO MODERATE (15 TO 20 KNOTS) VERTICAL WIND SHEAR,
DRY AIR ENTRAINMENT AND WEAK DIFFLUENCE ALOFT. TD 06W IS TRACKING
WEST-SOUTHWESTWARD UNDER THE STEERING INFLUENCE OF A LOW-LEVEL
SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH AND NORTHWEST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TD 06W IS FORECAST TO TRACK WESTWARD WITH A SLIGHT SOUTHERLY
COMPONENT THROUGH TAU 12. AS IT APPROACHES THE RYUKYU ISLANDS, THE
SYSTEM SHOULD TURN WESTWARD AS IT TRACKS ALONG THE SOUTHWEST
PERIPHERY OF THE STR. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO
REMAIN MARGINAL WITH LOW VWS AND DRY AIR ENTRAINMENT (700-500MB RH
VALUES OF 50-55%). THEREFORE, THE SYSTEM SHOULD REMAIN SHALLOW AND
WEAK, LIKELY DISSIPATING BY TAU 36 WITH SOME POTENTIAL FOR
DISSIPATION EARLIER IN THE FORECAST PERIOD. NUMERICAL MODEL GUIDANCE
IS IN TIGHT AGREEMENT THROUGH TAU 12 AND MOST MODELS ARE IN
AGREEMENT THROUGH TAU 36, WITH GFS BEING THE OUTLIER TURNING THE
SYSTEM SOUTHWESTWARD AFTER TAU 12. THEREFORE, THE JTWC FORECAST
TRACK IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH
CONFIDENCE.//
NNNN

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Final Warning


WTPN32 PGTW 130300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL DEPRESSION 06W (SIX) WARNING NR 015//
RMKS/
1. TROPICAL DEPRESSION 06W (SIX) WARNING NR 015
01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
130000Z --- NEAR 24.5N 131.5E
MOVEMENT PAST SIX HOURS - 260 DEGREES AT 14 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 015 KT, GUSTS 025 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
REPEAT POSIT: 24.5N 131.5E
---
FORECASTS:
12 HRS, VALID AT:
131200Z --- 24.3N 129.0E
MAX SUSTAINED WINDS - 015 KT, GUSTS 025 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER
---
REMARKS:
130300Z POSITION NEAR 24.4N 130.9E.
13AUG20. TROPICAL DEPRESSION 06W (SIX), LOCATED APPROXIMATELY 234
NM EAST-SOUTHEAST OF KADENA AB, OKINAWA, JAPAN HAS TRACKED
WESTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
MULTISPECTRAL IMAGERY REVEALS A RAPIDLY DECAYING SYSTEM WITH
SPARSE CONVECTION AND NO LOW LEVEL CIRCULATION CENTER (LLCC).
FURTHERMORE, A 130042Z ASCAT B IMAGE CONFIRMS THE LLCC HAS
DEVOLVED INTO AN OPEN WAVE. INTENSITY IS BASED ON THE 130042Z
ASCAT B IMAGE, WHICH SHOWS A MAXIMUM OF 15 KNOTS. THIS REMNANT
WAVE WILL CONTINUE TO TRACK WESTWARD OVER THE NEXT 12 HOURS.
THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON
WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED FOR
SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 130000Z
IS 12 FEET.
//
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