WPAC: CHANTHU - Post-Tropical

[stormwise]

Just like wxman57 said its sheared.

[euro6208]

WDPN31 PGTW 140300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHANTHU)
WARNING NR 04//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 09W (CHANTHU), LOCATED APPROXIMATELY 256 NM
SOUTH-SOUTHEAST OF IWO TO, HAS TRACKED NORTHEASTWARD AT 12 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
DEPICTS AN EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH A LARGE
AREA OF DEEP CONVECTION SHEARED OVER THE NORTHEAST QUADRANT OF THE
LLCC DUE TO STRONGLY DIFFLUENT SOUTHWESTERLY FLOW. A 132126Z SSMIS
91GHZ IMAGE REVEALS A BROAD LLCC POSITIONED ON THE SOUTHWEST EDGE OF
THE AFOREMENTIONED AREA OF DEEP CONVECTION, WHICH IS GENERALLY
ALIGNED TO THE NORTHEAST. BASED ON THE MSI, THERE IS GOOD CONFIDENCE
IN THE CURRENT POSITION. THE CURRENT INTENSITY IS ASSESSED AT 35
KNOTS BASED ON THE LOWER RANGE OF DVORAK ESTIMATES RANGING FROM T2.5
(35 KNOTS) TO T3.0 (45 KNOTS). UPPER-LEVEL ANALYSIS INDICATES A
MARGINALLY-FAVORABLE ENVIRONMENT WITH MODERATE TO STRONG
SOUTHWESTERLY VERTICAL WIND SHEAR (VWS) OFFSET BY STRONG DIFFLUENCE.
ANIMATED WATER VAPOR IMAGERY SHOWS GOOD POLEWARD AND EQUATORWARD
OUTFLOW, ENHANCED BY AN UPPER TROUGH TO THE WEST AND THE UPPER LOW
POSITIONED OVER TS 08W. TS 09W IS TRACKING ALONG THE WESTERN
PERIPHERY OF THE NEAR EQUATORIAL RIDGE (NER) TO THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 09W WILL CONTINUE TO TRACK NORTH-NORTHEASTWARD UNDER THE
STEERING INFLUENCE OF THE NER THROUGH TAU 24 THEN WILL TRACK
NORTHWARD TO NORTH-NORTHWESTWARD AS IT TRANSITIONS TO THE STEERING
INFLUENCE OF THE POLEWARD-ORIENTED SUBTROPICAL RIDGE (STR). WITH THE
EXCEPTION OF UKMET, NAVGEM AND JENS, THE DYNAMIC GUIDANCE IS IN
BETTER ALIGNMENT WITH THE POLEWARD TRACK OVER NORTHERN JAPAN. THE
DYNAMIC MODELS CONTINUE TO STRUGGLE WITH A FAIRLY COMPLEX
STEERING ENVIRONMENT AND REMAIN IN POOR AGREEMENT WITH TWO DISTINCT
CLUSTERS OF MODELS. THE FIRST CLUSTER (NAVGEM, UKMET, JENS AND JGSM)
INDICATE A SIGNIFICANTLY SLOWER, CYCLONIC TRACK WITH MODEL FIELDS
SHOWING ERRONEOUS DIRECT CYCLONE INTERACTION EXPECTED TO OCCUR AFTER
TAU 72. THE SECOND CLUSTER (COAMPS-TC, ECMWF, GFDN, HWRF, GFS AND
GFS ENSEMBLE) INDICATE A FASTER POLEWARD TRACK TOWARD NORTHERN
JAPAN. IN GENERAL, THE MODELS ARE CONSISTENT IN DEPICTING A DEEP
SHORTWAVE TROUGH DIGGING OVER CENTRAL JAPAN AFTER TAU 72 WITH A
POLEWARD-ORIENTED STR. AS MENTIONED BEFORE, THE MAJOR DIFFERENCE IS
IN HOW THE FIRST CLUSTER OF MODELS APPEAR TO ERRONEOUSLY INTERACT
WITH DEVELOPING POTENTIAL / DEVELOPING TROPICAL SYSTEMS. AT THIS
TIME, THE JTWC TRACK FORECAST FAVORS THE FASTER, POLEWARD TRACK AS
SUPPORTED BY THE GENERAL SYNOPTIC SCENARIO AND THE SECOND CLUSTER OF
DYNAMIC MODELS. CURRENT INTENSITY GUIDANCE INDICATES A SLOW
INTENSIFICATION TREND UP TO 60 KNOTS. BEYOND TAU 36, THE
INTENSIFICATION IS BEING HINDERED BY SLIGHTLY COOLER SEA SURFACE
TEMPERATURES AND OCEAN HEAT CONTENT IN THE WAKE OF TS 08W.
C. TS 09W IS FORECAST TO CONTINUE A POLEWARD TRACK THROUGHOUT THE
REMAINDER OF THE FORECAST PERIOD AS IT TRACKS ALONG THE WESTERN
PERIPHERY OF THE STR, AHEAD OF THE MIDLATITUDE SHORTWAVE TROUGH. TS
09W SHOULD WEAKEN AS IT APPROACHES JAPAN DUE TO INCREASING VWS AND
INTERACTION WITH LAND. ADDITIONALLY, THE SYSTEM WILL BEGIN EXTRA-
TROPICAL TRANSITION (ETT) BY TAU 96 AND WILL COMPLETE ETT BY TAU
120. DUE TO THE BIFURCATION IN THE MODEL GUIDANCE, THERE IS LOW
OVERALL CONFIDENCE IN THE JTWC TRACK FORECAST.//
NNNN

[stormwise]

On the 11 utc pass the storm was elongated and likely no better a TD.

[euro6208]

One of the best prognostic I've ever read.

Wasn't this the system the GFS had bottoming out sub -900mb?

If it weren't for the strong wind shear, everything was primed for it...

[stormwise]

From what i can see looking over the archives euro6208, you have been the backbone of this WPAC thread for many years and its a credit to you.
You also would know nobody takes the GFS long range with 900mb storm outputs with a grain of salt.

[euro6208]

From what i can see looking over the archives euro6208, you have been the backbone of this WPAC thread for many years and its a credit to you.
You also would know nobody takes the GFS long range with 900mb storm outputs with a grain of salt.

I know that just kinda disappointed it didn't pan out.

[euro6208]

WDPN31 PGTW 140900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHANTHU) WARNING
NR 05//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 09W (CHANTHU), LOCATED APPROXIMATELY 186 NM
SOUTHEAST OF IWO TO, HAS TRACKED NORTH-NORTHEASTWARD AT 16 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS A FAST MOVING PARTIALLY EXPOSED LOW-LEVEL CIRCULATION
CENTER (LLCC) WITH A LARGE AREA OF DEEP CONVECTION SHEARED OVER THE
NORTHEAST QUADRANT DUE TO STRONGLY DIFFLUENT SOUTHWESTERLY FLOW. A
140602Z SSMIS 91 GHZ IMAGE REVELS THE LLCC IS STILL STRUGGLING TO
BECOME ORGANIZED, WITH AN ILL-DEFINED BROAD CENTER LOCATED NEAR THE
SOUTHWESTERN EDGE OF THE DEEP CONVECTION. THE INITIAL POSITION IS
BASED ON THE PGTW FIX AND AFOREMENTED SSMIS IMAGE WITH FAIR
CONFIDENCE, AND REFLECTS A 70 NM DIFFERENCE FROM THE EXPECTED
POSITION, RESULTING IN A RELOCATION OF THE LLCC. THE CURRENT
INTENSITY IS ASSESSED AT 35 KNOTS BASED ON DVORAK ESTIMATES OF T2.5
(35 KNOTS). UPPER-LEVEL ANALYSIS INDICATES A MARGINALLY-FAVORABLE
ENVIRONMENT WITH MODERATE TO STRONG SOUTHWESTERLY VERTICAL WIND
SHEAR (VWS) OFFSET BY STRONG DIFFLUENCE. ANIMATED WATER VAPOR
IMAGERY SHOWS GOOD POLEWARD AND EQUATORWARD OUTFLOW, ENHANCED BY AN
UPPER TROUGH TO THE WEST AND THE UPPER LOW POSITIONED OVER TS 08W.
TS 09W IS TRACKING ALONG THE WESTERN PERIPHERY OF THE NEAR
EQUATORIAL RIDGE (NER) TO THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE, HOWEVER, THE INITIAL POSITION HAS BEEN
RELOCATED 70 NM AHEAD OF THE EXPECTED BEST TRACK POSITION BASED ON
MICROWAVE DATA.
B. TS 09W WILL CONTINUE TO TRACK NORTH-NORTHEASTWARD UNDER THE
STEERING INFLUENCE OF THE NER THROUGH TAU 12 THEN WILL TRACK
NORTHWARD TO NORTH-NORTHWESTWARD AS IT TRANSITIONS TO THE STEERING
INFLUENCE OF THE POLEWARD-ORIENTED SUBTROPICAL RIDGE (STR). THE
DYNAMIC MODELS CONTINUE TO STRUGGLE WITH A FAIRLY COMPLEX STEERING
ENVIRONMENT, RESULTING IN A SIGNIFICANT BI-FURCATION, HOWEVER,
AGREEMENT HAS BEEN IMPROVING IN THE LATEST MODEL RUNS. THE FIRST
MODEL GROUPING (NAVGEM, UKMET, JENS AND JGSM) INDICATE A
SIGNIFICANTLY SLOWER, CYCLONIC TRACK WITH MODEL FIELDS SHOWING
ERRONEOUS DIRECT CYCLONE INTERACTION EXPECTED TO OCCUR AFTER TAU 72.
THE SECOND CLUSTER (COAMPS-TC, ECMWF, GFDN, HWRF, GFS AND GFS
ENSEMBLE) INDICATE A FASTER POLEWARD TRACK TOWARD NORTHERN JAPAN. IN
GENERAL, THE MODELS ARE CONSISTENT IN DEPICTING A DEEP SHORTWAVE
TROUGH DIGGING OVER CENTRAL JAPAN AFTER TAU 72 WITH A POLEWARD-
ORIENTED STR. AS MENTIONED BEFORE, THE MAJOR DIFFERENCE IS THE
RESULT OF ERRONEOUS BINARY INTERACTION IN THE FIRST CLUSTER. AT THIS
TIME, THE JTWC TRACK FORECAST FAVORS THE FASTER, POLEWARD TRACK AS
SUPPORTED BY THE GENERAL SYNOPTIC SCENARIO AND THE SECOND CLUSTER OF
DYNAMIC MODELS. CURRENT INTENSITY GUIDANCE INDICATES A SLOW
INTENSIFICATION TREND UP TO 55 KNOTS.
C. TS 09W IS FORECAST TO CONTINUE A POLEWARD TRACK THROUGHOUT THE
REMAINDER OF THE FORECAST PERIOD AS IT TRACKS ALONG THE WESTERN
PERIPHERY OF THE STR, AHEAD OF THE MIDLATITUDE SHORTWAVE TROUGH. TS
09W SHOULD WEAKEN AS IT APPROACHES JAPAN DUE TO INCREASING VWS AND
INTERACTION WITH LAND. ADDITIONALLY, THE SYSTEM WILL BEGIN EXTRA-
TROPICAL TRANSITION (ETT) BY TAU 96 AND WILL COMPLETE ETT BY TAU
120. DUE TO THE BIFURCATION IN THE MODEL GUIDANCE, THERE IS LOW
OVERALL CONFIDENCE IN THE JTWC TRACK FORECAST.//
NNNN

[wxman57]

Just got a good ASCAT (11Z). Can't see any 50kt barbs, but it looks like Chanthu is at least 40-45 kts. Could be some 50kt winds NE of the center.

[NotoSans]

JMA up to 45 kt at 12Z while JTWC is at 40 kt.

[doraboy]

Predicted by TCFS(TC Formation Simulator) V1.07
Initial time:2016/08/14 12UTC

PS:The forecast is based on my own "model" (a small C++ program I wrote)
http://i.imgur.com/iojcfkj.jpg
http://i.imgur.com/MisFBqd.jpg

[wxman57]

Predicted by TCFS(TC Formation Simulator) V1.07
Initial time:2016/08/14 12UTC

PS:The forecast is based on my own "model" (a small C++ program I wrote)
http://i.imgur.com/iojcfkj.jpg
http://i.imgur.com/MisFBqd.jpg

This appears to be in the wrong thread. Has nothing to do with Chanthu.

[euro6208]

WDPN31 PGTW 142100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHANTHU) WARNING
NR 07//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 09W (CHANTHU), LOCATED APPROXIMATELY 181 NM
SOUTHEAST OF CHICHI JIMA, HAS TRACKED AT 11 KNOTS OVER THE PAST
SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A
PARTIALLY-EXPOSED, LOW-LEVEL CIRCULATION CENTER (LLCC) POSITIONED ON
THE SOUTHERN EDGE OF A LARGE AREA OF DEEP CONVECTION DUE TO
PERSISTENT SOUTHERLY VERTICAL WIND SHEAR (VWS). A 141832Z SSMIS 37
GHZ IMAGE SUPPORTS THE CURRENT POSITION WITH GOOD CONFIDENCE AND
SHOWS TIGHTLY-CURVED SHALLOW BANDING WRAPPING INTO A DEFINED CENTER.
THE 91GHZ IMAGE SHOWS CURVED DEEP CONVECTIVE BANDING OVER THE
NORTHERN SEMI-CIRCLE OF THE LLCC. BASED ON THE IMPROVED BANDING
STRUCTURE, THE CURRENT INTENSITY IS ASSESSED AT 45 KNOTS BASED ON
DVORAK INTENSITY ESTIMATES OF 45 KNOTS FROM ALL AGENCIES. UPPER-
LEVEL ANALYSIS INDICATES TS 09W REMAINS IN A MARGINALLY-FAVORABLE
ENVIRONMENT WITH HIGH (30 KNOTS) SOUTHERLY VWS OFFSET BY STRONG
DIFFLUENCE. SEA SURFACE TEMPERATURES (SSTS) ARE FALLING TO 27
DEGREES CELSIUS IN THE WAKE OF PRIOR TROPICAL CYCLONE ACTIVITY IN
THE AREA. TS 09W IS TRACKING ALONG THE WESTERN PERIPHERY OF THE NEAR
EQUATORIAL RIDGE (NER) TO THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE. 34-KNOT WIND RADII HAVE BEEN ADJUSTED
BASED ON A RECENT ASCAT IMAGE.
B. TS 09W WILL CONTINUE TO TRACK NORTHWARD UNDER THE STEERING
INFLUENCE OF THE NER THROUGH TAU 12 BEFORE TURNING NORTH-
NORTHWESTWARD AS IT TRANSITIONS TO THE STEERING INFLUENCE OF THE
POLEWARD-ORIENTED SUBTROPICAL RIDGE (STR). DYNAMICAL MODEL GUIDANCE
REMAINS IN GOOD AGREEMENT WITH ALL CONSENSUS MEMBERS SUPPORTING THE
POLEWARD TRACK SOLUTION WHICH TAKES CHANTHU UP THE EAST COAST OF
HONSHU WITHIN THE WELL DEFINED MERIDIONAL STEERING FLOW. DUE TO
FORECAST STRENGTHENING OF THE STR AND IMPROVED CONFIDENCE IN THE
MULTI-MODEL CONSENSUS SOLUTION, THE TAU 72 POSITION HAS BEEN
ADJUSTED FASTER THAN THE PREVIOUS WARNING. THE PEAK INTENSITY HAS
BEEN ADJUSTED SLIGHTLY TO 55 KNOTS, HOWEVER, TS 09W IS NOT EXPECTED
TO INTENSIFY FURTHER DUE TO THE PERSISTENTLY STRONG VWS AND
DEPRESSED SSTS. NEAR TAU 48, ADDITIONAL VWS IS EXPECTED IN RESPONSE
TO A SHORTWAVE TROUGH MOVING IN FROM THE WEST, LEADING TO A
WEAKENING TREND. EXTRATROPICAL TRANSITION (ETT) IS EXPECTED TO BEGIN
BY TAU 48. TS 09W WILL COMPLETE ETT BY TAU 96. DESPITE MUCH IMPROVED
MODEL AGREEMENT, THERE REMAINS SIGNIFICANT DIFFERENCES IN THE SPEED
OF MOTION AFTER TAU 36, RESULTING IN LOW CONFIDENCE IN THE JTWC
FORECAST TRACK.//
NNNN

[stormwise]

Code: Select all

0814/12Z MODELS: CHANTHU
(2016-08-14 23:00:19 UTC)
==========================
                 ECMWF - IFS
TIME        (HR)     0     6    12    18    24    30    36    42    48    60    72    84    96   108   120   132   144   156   168
LATITUDE   (DEG)  24.1  25.6  26.5  28.1  28.7  29.9  31.0  32.7  33.9  37.2  42.3  49.8  56.2  60.4  64.1  66.6  66.2  66.0  67.9
LONGITUDE  (DEG) 144.2 144.3 144.7 144.5 143.6 143.5 143.4 142.7 142.1 142.2 144.2 146.3 148.8 152.3 160.5 171.7 178.0 185.4 192.0
MAX WIND    (KT)    35    35    37    41    38    35    38    38    43    40    45    38    38    38    19    16    19    27    31
                 NCEP - GFS:
TIME        (HR)     0     6    12    18    24    30    36    42    48    60    72    84    96   108   120   132   144
LATITUDE   (DEG)  24.5  25.6  26.8  27.8  28.2  29.2  29.9  30.7  31.7  34.7  38.4  45.1  50.7  57.1  60.0  60.3  59.4
LONGITUDE  (DEG) 144.7 144.6 144.5 144.2 143.7 143.1 142.4 141.6 140.8 140.5 141.8 142.9 144.3 147.0 147.5 148.0 150.4
MAX WIND    (KT)    44    40    40    42    42    38    40    36    39    49    60    56    46    44    35    21    12
                 UKMO - UM:
TIME        (HR)     0     6    12    18    24    30    36    42    48    60    72    84    96   108   120   132   144   156   168
LATITUDE   (DEG)  23.9  25.4  26.6  27.5  28.1  29.0  29.9  30.7  31.8  34.5  38.8  44.3  48.7  54.0  57.4  59.1  61.3  61.8  60.0
LONGITUDE  (DEG) 144.4 144.7 144.3 143.9 143.2 142.4 141.5 140.6 139.8 139.7 140.9 141.5 143.0 145.2 147.6 152.6 161.8 173.6 183.8
MAX WIND    (KT)    35    43    41    44    44    40    39    42    45    55    51    41    47    38    35    34    31    21    31
                 CMC - GEM:
TIME        (HR)     0     6    12    18    24    30    36    42    48    60    72    84    96   108   120   132   144   156   168
LATITUDE   (DEG)  24.2  25.0  26.2  26.8  28.0  28.8  29.4  30.0  30.4  32.4  33.2  33.9  32.9  31.0  29.2  28.2  27.5  27.3  27.0
LONGITUDE  (DEG) 144.4 144.4 144.3 144.1 144.0 143.2 142.5 141.7 141.1 139.9 139.3 138.7 137.3 136.0 134.9 133.6 131.9 129.3 126.3
MAX WIND    (KT)    37    38    40    37    37    39    36    32    32    39    43    31    40    27    25    27    26    25    28
                 FNMOC - NAVGEM:
TIME        (HR)     0     6    12    18    24    30    36    42    48    60    72    84    96
LATITUDE   (DEG)  24.0  25.7  27.2  28.5  29.6  30.8  32.1  33.5  35.1  39.1  44.8  51.4  58.3
LONGITUDE  (DEG) 144.5 144.8 144.6 144.5 144.1 143.4 142.8 142.1 141.8 142.6 144.7 147.9 150.1
MAX WIND    (KT)    40    36    36    35    37    36    36    38    39    44    43    36    27
                 ESRL - FIM8:
TIME        (HR)     0     6    12    18    24    30    36    42    48    60    72    84    96   108   120   132   144
LATITUDE   (DEG)  24.5  25.5  26.7  27.6  28.3  29.1  29.7  30.6  31.4  33.4  35.7  39.1  42.4  47.3  53.2  58.9  61.0
LONGITUDE  (DEG) 144.7 144.5 144.4 144.0 143.3 142.5 141.8 140.9 140.0 139.3 140.1 141.5 142.3 144.6 148.8 153.7 157.5
MAX WIND    (KT)    46    40    41    41    43    40    38    39    41    45    50    44    35    35    30    28    35
                 ESRL - FIM9:
TIME        (HR)     0     6    12    18    24    30    36    42    48    60    72    84    96   108   120   132
LATITUDE   (DEG)  24.5  25.6  26.8  27.7  28.4  29.3  30.0  30.9  31.8  34.2  37.9  43.6  48.6  55.1  59.8  64.5
LONGITUDE  (DEG) 144.8 144.6 144.4 144.1 143.4 142.7 142.0 141.3 140.5 140.0 141.2 142.6 144.3 147.7 150.4 158.0
MAX WIND    (KT)    47    41    42    43    44    42    42    42    44    53    59    44    48    50    41    24

ECMWF/NCEP - GFS/ UKMO - UM/CMC - GEM/FNMOC - NAVGEM/ESRL - FIM8/FIM9


JTWC Best tracks.... 09W CHANTHU 160815 0000 26.4N 144.7E WPAC 45 989



UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 15 AUG 2016 Time : 023000 UTC
Lat : 27:00:53 N Lon : 144:49:07 E


CI# /Pressure/ Vmax
3.4 / 979.4mb/ 53.0kt


Final T# Adj T# Raw T#
2.5 2.5 2.5

Center Temp : +1.6C Cloud Region Temp : -21.8C

Doing better on ADT, with warming.

[euro6208]

WDPN31 PGTW 150300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHANTHU) WARNING
NR 08//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 09W (CHANTHU), LOCATED APPROXIMATELY 586 NM
SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHWARD AT 14 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
AND A 150026Z METOP-B 89GHZ IMAGE DEPICT AN EXPOSED BUT TIGHTLY-
WRAPPED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH DEEP CONVECTION
LIMITED TO THE NORTHWEST QUADRANT OF THE LLCC. DESPITE THE RECENT
DECREASE IN CORE CONVECTION DUE TO DIURNAL TRENDS AND PERSISTENT
MODERATE TO STRONG SOUTHERLY VERTICAL WIND SHEAR (VWS), A 150028Z
ASCAT IMAGE SHOWS NUMEROUS 40 TO 45 KNOT WINDS OVER THE NORTHEAST
AND SOUTHWEST QUADRANTS. THEREFORE, THE CURRENT INTENSITY REMAINS
ASSESSED AT 45 KNOTS, WHICH IS CONSISTENT WITH BOTH THE STRUCTURE
AND DVORAK INTENSITY ESTIMATES OF T3.0 (45 KNOTS). ADDITONALLY, TS
09W HAS MAINTAINED A NEAR-SYMMETRIC DEEP MOISTURE ENVELOPE, WHICH
SHOULD ALLOW FOR RE-INTENSIFICATION DURING DIURNAL MAXIMUM IN 12 TO
18 HOURS. ANIMATED WATER VAPOR IMAGERY INDICATES IMPROVING POLEWARD
OUTFLOW INTO THE UPPER LOW SOUTHEAST OF HOKKAIDO, JAPAN (THIS LOW IS
POSITIONED OVER TS 08W, WHICH IS NOW EXTRA-TROPICAL). UPPER-
LEVEL ANALYSIS INDICATES TS 09W REMAINS IN AN IMPROVING, FAVORABLE
ENVIRONMENT WITH LOW TO MODERATE (15 TO 30 KNOTS) VWS AND GOOD
OVERALL OUTFLOW. SEA SURFACE TEMPERATURES (SSTS) RANGE FROM 28C TO
29C BUT DECREASE TO LESS THAN 26C NORTH OF 35N LATITUDE. TS 09W IS
TRACKING ALONG THE WESTERN PERIPHERY OF THE POLEWARD-ORIENTED
SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 09W WILL CONTINUE TO TRACK NORTHWARD UNDER THE STEERING
INFLUENCE OF THE STEERING INFLUENCE OF THE AFOREMENTIONED STR.
DYNAMICAL MODEL GUIDANCE REMAINS IN GOOD AGREEMENT WITH ALL
CONSENSUS MEMBERS SUPPORTING THE POLEWARD TRACK SOLUTION WHICH TAKES
CHANTHU UP THE EAST COAST OF HONSHU WITHIN THE WELL DEFINED
MERIDIONAL STEERING FLOW. AS MENTIONED PREVIOUSLY, TS 09W IS
FORECAST TO INTENSIFY SLIGHTLY TO A PEAK OF 55 KNOTS BY TAU 24 DUE
TO FAVORABLE CONDITIONS AND DIURNAL MAXIMUM. ADDITIONALLY, 09W'S
NORTHWARD ACCELERATION WILL LIKELY OFFSET THE SOUTHERLY VWS
SUFFICIENTLY TO ALLOW FOR RE-DEVELOPMENT OF THE CORE CONVECTION.
AFTER TAU 24, TS 09W WILL WEAKEN GRADUALLY AS IT ENCOUNTERS
INCREASING VWS ASSOCIATED WITH A DEEP MIDLATITUDE SHORTWAVE TROUGH
AND BEGINS TO INTERACT WITH THE BAROCLINIC ZONE, COMMENCING EXTRA-
TROPICAL TRANSITION (ETT). TS 09W WILL COMPLETE ETT BY TAU 72.
OVERALL, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST SINCE THE
DYNAMIC MODELS ARE IN TIGHT AGREEMENT.//
NNNN

[stormwise]

Dry Air and shear is wining the battle atm.

[euro6208]

Another lackluster storm...

[Kingarabian]

Another lackluster storm...

Epac went though the same thing my friend. Despite numerous models forecasting certain storms to be stronger than what they became.

[euro6208]

WDPN31 PGTW 150900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHANTHU) WARNING
NR 09//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 09W (CHANTHU), LOCATED APPROXIMATELY 515 NM SOUTH-
SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHWARD AT 13 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL IMAGERY AND A
150028Z METOP-B ASCAT IMAGE SHOWS A BROAD SYSTEM WITH LIMITED DEEP
CONVECTIVE BANDING AND A TIGHTLY WRAPPED LOW LEVEL CIRCULATION
CENTER (LLCC). THE INITIAL POSITION IS BASED ON A 150429Z MHS 89GHZ
IMAGE WITH GOOD CONFIDENCE SHOWING THE CONVECTIVE ACTIVITY LIMITED
TO THE NORTH AND WESTERN QUADRANTS. THE INITIAL INTENSITY IS BASED
ON DVORAK ESTIMATES FROM ALL AGENCIES REPORTING A CURRENT INTENSITY
OF T3.0 (45 KNOTS) AND THE AFOREMENTIONED ASCAT IMAGE SHOWING
DEFINITIVE 45 KNOT WINDS ON THE NORTHEAST QUADRANT. SEA SURFACE
TEMPERATURES ARE WARM NEAR 29 CELSIUS. VERTICAL WIND SHEAR (VWS) IS
FAVORABLE (NEAR 15 KNOTS) AND DUAL CHANNEL OUTFLOW IS EVIDENT IN
ANIMATED SATELLITE WATER VAPOR IMAGERY. CIMSS TOTAL PRECIPITABLE
WATER (TPW) PRODUCT INDICATES THAT DRY AIR IS BEGINNING TO ENCIRCLE
THE SYSTEM. TS 09W IS CURRENTLY TRACKING NORTHWARD ALONG THE
PERIPHERY OF A MID TO LOW LEVEL SUBTROPICAL RIDGE TO THE EAST.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 09W IS EXPECTED TO CONTINUE ITS TRACK NORTHWARD UNDER THE
INFLUENCE OF THE STEERING RIDGE THROUGH TAU 36. SLIGHT
INTENSIFICATION IS EXPECTED THROUGH TAU 36 AS A MID LATITUDE TROUGH
MOVES IN OVER JAPAN ENHANCING POLEWARD OUTFLOW. BEYOND TAU 36,
INTERACTION WITH THE TROUGH WILL INCREASE VWS AND BAROCLINICITY AS
TS 09W STARTS TO UNDERGO EXTRATROPICAL TRANSITION, AND BECOMING
EXTRATROPICAL BY TAU 72. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT
WITH THE TRACK PATH, HOWEVER, THERE IS A LARGE DISAGREEMENT ON THE
SPEED OF ADVANCE AS THE SYSTEM BECOMES ENVELOPED IN THE TROUGH. THE
FORECAST TRACK IS PLACED WITH HIGH CONFIDENCE NEAR THE MULTI-MODEL
CONSENSUS.//
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[euro6208]

WDPN31 PGTW 152100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHANTHU) WARNING
NR 11//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 09W (CHANTHU), LOCATED APPROXIMATELY 343 NM SOUTH-
SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT
13 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS A BROAD CIRCULATION NEARLY COMPLETELY
DEVOID OF DEEP CONVECTION. ONLY A SMALL AREA OF FLARING CONVECTION
PERSISTS NEAR THE LOW-LEVEL CIRCULATION CENTER (LLCC). THE INITIAL
POSITION IS BASED ON A 151818Z SSMIS 91GHZ IMAGE WITH GOOD
CONFIDENCE. THE INITIAL INTENSITY IS BASED ON DVORAK AND
EXTRATROPICAL INTENSITY FIXES FROM RJTD AND PGTW OF T2.5. ALTHOUGH
SEA SURFACE TEMPERATURES ARE WARM AND VERTICAL WIND SHEAR REMAINS
LOW (5-10 KNOTS), RESTRICTED OUTFLOW AND DRY AIR ENTRAINMENT TO THE
WEST AND SOUTH IS SUPPRESSING THE MAINTENANCE OF DEEP CONVECTION. TS
09W IS CURRENTLY TRACKING ALONG THE WESTERN PERIPHERY OF A
SUBTROPICAL RIDGE TO THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE, EXCEPT THE INTENSITY FORECAST HAS BEEN
SLIGHTLY REDUCED GIVEN THE DOWNWARD TREND IN CONVECTIVE INTENSITY.
B. TS 09W IS EXPECTED TO CONTINUE ITS TRACK NORTH-NORTHWESTWARD
UNDER THE INFLUENCE OF THE STEERING RIDGE THROUGH TAU 24. FUTURE
INTENSIFICATION IS NO LONGER LIKELY GIVEN THE DISORGANIZED STATE OF
CONVECTION ASSOCIATED WITH THE LLCC. BEYOND TAU 24, VERTICAL WIND
SHEAR IS FORECAST TO INCREASE WHILE TS 09W MERGES WITH A MID-
LATITUDE TROUGH AND SUBSEQUENTLY COMPLETES EXTRATROPICAL TRANSITION.
DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE TRACK FORECAST.
HOWEVER, THERE IS SOME UNCERTAINTY REGARDING THE FORWARD MOTION
BEYOND TAU 24 AFTER TS 09W COMPLETES EXTRATROPICAL TRANSITION AND IS
EMBEDDED WITHIN THE MID-LATITUDE FLOW. OVERALL, THE FORECAST TRACK
IS PLACED WITH HIGH CONFIDENCE NEAR THE MULTI-MODEL CONSENSUS.//
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[euro6208]

WDPN31 PGTW 160900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHANTHU) WARNING
NR 13//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 09W (CHANTHU), LOCATED APPROXIMATELY 145 NM
SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT 19
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) DEPICTS A WELL-DEFINED AND PARTLY EXPOSED LOW LEVEL
CIRCULATION CENTER (LLCC) WITH SHALLOW CENTRAL CONVECTION DISPLACED
TO THE NORTHERN PERIPHERIES. THE INITIAL POSITION IS BASED ON THE MSI
LOOP WITH HIGH CONFIDENCE. THE INITIAL INTENSITY IS HELD SLIGHTLY
HIGHER THAN AGENCY DVORAK ESTIMATES BASED ON A RECENT ASCAT PASS.
UPPER LEVEL CONDITIONS ARE MARGINAL DUE TO DRY AIR ENTRAINMENT FROM
AN UPPER LEVEL LOW POSITIONED TO THE SOUTHWEST AND WEAK DIFFLUENCE
ALOFT;
HOWEVER, LOW VERTICAL WIND SHEAR AND SEA SURFACE TEMPERATURES ABOVE
26 CELSIUS REMAIN SOMEWHAT FAVORABLE. TS 09W IS CURRENTLY TRACKING
ALONG THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS CHANTHU IS EXPECTED TO CONTINUE ITS TRACK NORTH-NORTHWESTWARD
UNDER THE INFLUENCE OF THE STEERING RIDGE OVER THE NEXT 12 HOURS.
AFTERWARDS, THE CYCLONE WILL TRACK MORE NORTH-NORTHEASTWARD AS THE
STR WEAKENS IN RESPONSE TO AN APPROACHING MID-LATITUDE TROUGH.
CONCURRENTLY, TS 09W WILL SLIGHTLY WEAKEN AND BEGIN EXTRA-TROPICAL
TRANSITION, BECOMING A COLD-CORE LOW WITH GALE-FORCE WINDS BY TAU 36.
DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT LENDING HIGH
CONFIDENCE TO THE CURRENT JTWC TRACK FORECAST.//
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