WPAC: MALAKAS (1012/13W) - Ex Typhoon
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- StormingB81
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From the latest ITOP weather summary:
Current Conditions/Review of Yesterday's Forecast:
Steering Mechanism:
Loop of 500 hPa steering
ECMWF strike probability: Image 11
Loop of Uppers
DAY 1 (Tomorrow) Update:
ITOP22: Increasing organization evident on satellite loop. High
certainty now of a single low level center with maximum winds of
35 knots (1 min. mean) - 13W. Favourable outflow pattern
suggests intensification ongoing for next 48 to 732 hours as it
slows and then heads north and then northeast - rolling around
the western flank of the dominant 500 mb high, ahead of a
mid-latitude trough to its west. Becomes extra-tropical around
25/00Z.
ITOP Center guidance chart:
report.forecast.201009202248.graphic.gif
JTWC guidance:
ops.JTWC_track.201009201800.13_track.gif
TROPICAL CYCLONE BRIEF
Storm ID: ITOP022 Name: ITOP022
Issued at: 2247 UTC 20/09/2010
Data at: 1800 UTC 20 September 2010
TECHNICAL REMARKS
** Working track only - for information **
2 x ECMWF and1 x UK Track and 1 x GFS. Variability in speed of
recurvature in models but all consistent in their handling of
track.
Latitude: 16.9N
Longitude: 144.2E
Location Accuracy: within 90 nm (165 km)
Movement Towards: west (260 deg)
Speed of Movement: 17 knots (31 km/h)
Bearing 1: From Guam
At +0: 210 nm (390 km) north
At +12: 255 nm (470 km) north northwest
At +24: 270 nm (500 km) north northwest
At +36: 310 nm (580 km) north northwest
At +48: 390 nm (730 km) north northwest
At +60: 480 nm (890 km) north northwest
At +72: 570 nm (1060 km) north northwest
FORECAST DATA *** Mean wind is 10 minute mean wind ***
Date/Time : Location : Acc : Mean: Max : Pres :
(UTC) : degrees : nm : kts : kts : hPa : 3
+0 : 20/1800 : 16.9N 144.2E : 090 : 030 : 045 : 1000 :
+6 : 21/0000 : 17.4N 143.6E : 105 : 035 : 050 : :
+12 : 21/0600 : 17.5N 143.5E : 120 : 040 : 055 : :
+18 : 21/1200 : 17.6N 143.4E : 135 : 040 : 055 : :
+24 : 21/1800 : 17.7N 143.1E : 150 : 045 : 065 : :
+36 : 22/0600 : 18.2N 142.5E : 180 : 055 : 075 : :
+48 : 22/1800 : 19.3N 141.7E : 210 : 060 : 085 : :
+60 : 23/0600 : 20.7N 141.4E : 260 : 070 : 100 : :
+72 : 23/1800 : 22.4N 141.3E : 310 : 075 : 105 : :
+84 : 24/0600 : 25.0N 142.3E : 310 : 080 : 110 : :
+96 : 24/1800 : 28.7N 144.7E : 310 : 080 : 110 : :
+108 : 25/0600 : 33.4N 149.3E : 310 : 075 : 105 : :
+120 : 25/1800 : : : : : :
+132 : 26/0600 : : : : : :
+144 : 26/1800 : : : : : :
*** 10 minute mean wind - increase by about 10% to get to 1
minute mean wind***
Current Conditions/Review of Yesterday's Forecast:
Steering Mechanism:
Loop of 500 hPa steering
ECMWF strike probability: Image 11
Loop of Uppers
DAY 1 (Tomorrow) Update:
ITOP22: Increasing organization evident on satellite loop. High
certainty now of a single low level center with maximum winds of
35 knots (1 min. mean) - 13W. Favourable outflow pattern
suggests intensification ongoing for next 48 to 732 hours as it
slows and then heads north and then northeast - rolling around
the western flank of the dominant 500 mb high, ahead of a
mid-latitude trough to its west. Becomes extra-tropical around
25/00Z.
ITOP Center guidance chart:
report.forecast.201009202248.graphic.gif
JTWC guidance:
ops.JTWC_track.201009201800.13_track.gif
TROPICAL CYCLONE BRIEF
Storm ID: ITOP022 Name: ITOP022
Issued at: 2247 UTC 20/09/2010
Data at: 1800 UTC 20 September 2010
TECHNICAL REMARKS
** Working track only - for information **
2 x ECMWF and1 x UK Track and 1 x GFS. Variability in speed of
recurvature in models but all consistent in their handling of
track.
Latitude: 16.9N
Longitude: 144.2E
Location Accuracy: within 90 nm (165 km)
Movement Towards: west (260 deg)
Speed of Movement: 17 knots (31 km/h)
Bearing 1: From Guam
At +0: 210 nm (390 km) north
At +12: 255 nm (470 km) north northwest
At +24: 270 nm (500 km) north northwest
At +36: 310 nm (580 km) north northwest
At +48: 390 nm (730 km) north northwest
At +60: 480 nm (890 km) north northwest
At +72: 570 nm (1060 km) north northwest
FORECAST DATA *** Mean wind is 10 minute mean wind ***
Date/Time : Location : Acc : Mean: Max : Pres :
(UTC) : degrees : nm : kts : kts : hPa : 3
+0 : 20/1800 : 16.9N 144.2E : 090 : 030 : 045 : 1000 :
+6 : 21/0000 : 17.4N 143.6E : 105 : 035 : 050 : :
+12 : 21/0600 : 17.5N 143.5E : 120 : 040 : 055 : :
+18 : 21/1200 : 17.6N 143.4E : 135 : 040 : 055 : :
+24 : 21/1800 : 17.7N 143.1E : 150 : 045 : 065 : :
+36 : 22/0600 : 18.2N 142.5E : 180 : 055 : 075 : :
+48 : 22/1800 : 19.3N 141.7E : 210 : 060 : 085 : :
+60 : 23/0600 : 20.7N 141.4E : 260 : 070 : 100 : :
+72 : 23/1800 : 22.4N 141.3E : 310 : 075 : 105 : :
+84 : 24/0600 : 25.0N 142.3E : 310 : 080 : 110 : :
+96 : 24/1800 : 28.7N 144.7E : 310 : 080 : 110 : :
+108 : 25/0600 : 33.4N 149.3E : 310 : 075 : 105 : :
+120 : 25/1800 : : : : : :
+132 : 26/0600 : : : : : :
+144 : 26/1800 : : : : : :
*** 10 minute mean wind - increase by about 10% to get to 1
minute mean wind***
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WTPN32 PGTW 210300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL STORM 13W (THIRTEEN) WARNING NR 004 RELOCATED
01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
210000Z --- NEAR 18.4N 145.3E
MOVEMENT PAST SIX HOURS - 240 DEGREES AT 04 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
REPEAT POSIT: 18.4N 145.3E
---
FORECASTS:
12 HRS, VALID AT:
211200Z --- 18.4N 144.3E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
055 NM SOUTHEAST QUADRANT
055 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 290 DEG/ 06 KTS
---
24 HRS, VALID AT:
220000Z --- 18.8N 143.2E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
065 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 305 DEG/ 06 KTS
---
36 HRS, VALID AT:
221200Z --- 19.5N 142.1E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT
080 NM SOUTHEAST QUADRANT
080 NM SOUTHWEST QUADRANT
080 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 325 DEG/ 06 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
230000Z --- 20.5N 141.3E
MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT
025 NM SOUTHEAST QUADRANT
025 NM SOUTHWEST QUADRANT
025 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT
090 NM SOUTHEAST QUADRANT
090 NM SOUTHWEST QUADRANT
095 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 000 DEG/ 11 KTS
---
72 HRS, VALID AT:
240000Z --- 24.8N 141.4E
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
025 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 065 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
055 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 130 NM NORTHEAST QUADRANT
115 NM SOUTHEAST QUADRANT
095 NM SOUTHWEST QUADRANT
100 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 030 DEG/ 21 KTS
---
LONG RANGE OUTLOOK:
NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM
ON DAY 4 AND 350 NM ON DAY 5... AND FOR INTENSITY
NEAR 20 KT EACH DAY.
---
96 HRS, VALID AT:
250000Z --- 32.1N 146.0E
MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
WIND RADII VALID OVER OPEN WATER ONLY
BECOMING EXTRATROPICAL
VECTOR TO 120 HR POSIT: 030 DEG/ 31 KTS
---
120 HRS, VALID AT:
260000Z --- 42.4N 154.9E
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
EXTRATROPICAL
---
REMARKS:
210300Z POSITION NEAR 18.4N 145.0E.
TROPICAL STORM (TS) 13W (THIRTEEN), LOCATED APPROXIMATELY 190 NM
NORTH OF SAIPAN, HAS TRACKED WEST-SOUTHWESTWARD AT 04 KNOTS OVER THE
PAST SIX HOURS. JUSTIFICATION FOR RELOCATION: POSITION RELOCATED
SOUTHWARD BASED ON NEWLY AVAILABLE MULTISPECTRAL AND MICROWAVE
SATELLITE IMAGERY. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 210000Z IS 12
FEET. NEXT WARNINGS AT 210900Z, 211500Z, 212100Z AND 220300Z.//
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL STORM 13W (THIRTEEN) WARNING NR 004 RELOCATED
01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
210000Z --- NEAR 18.4N 145.3E
MOVEMENT PAST SIX HOURS - 240 DEGREES AT 04 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
REPEAT POSIT: 18.4N 145.3E
---
FORECASTS:
12 HRS, VALID AT:
211200Z --- 18.4N 144.3E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
055 NM SOUTHEAST QUADRANT
055 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 290 DEG/ 06 KTS
---
24 HRS, VALID AT:
220000Z --- 18.8N 143.2E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
065 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 305 DEG/ 06 KTS
---
36 HRS, VALID AT:
221200Z --- 19.5N 142.1E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 085 NM NORTHEAST QUADRANT
080 NM SOUTHEAST QUADRANT
080 NM SOUTHWEST QUADRANT
080 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 325 DEG/ 06 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
230000Z --- 20.5N 141.3E
MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT
025 NM SOUTHEAST QUADRANT
025 NM SOUTHWEST QUADRANT
025 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT
090 NM SOUTHEAST QUADRANT
090 NM SOUTHWEST QUADRANT
095 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 000 DEG/ 11 KTS
---
72 HRS, VALID AT:
240000Z --- 24.8N 141.4E
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
025 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 065 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
055 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 130 NM NORTHEAST QUADRANT
115 NM SOUTHEAST QUADRANT
095 NM SOUTHWEST QUADRANT
100 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 030 DEG/ 21 KTS
---
LONG RANGE OUTLOOK:
NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM
ON DAY 4 AND 350 NM ON DAY 5... AND FOR INTENSITY
NEAR 20 KT EACH DAY.
---
96 HRS, VALID AT:
250000Z --- 32.1N 146.0E
MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
WIND RADII VALID OVER OPEN WATER ONLY
BECOMING EXTRATROPICAL
VECTOR TO 120 HR POSIT: 030 DEG/ 31 KTS
---
120 HRS, VALID AT:
260000Z --- 42.4N 154.9E
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
EXTRATROPICAL
---
REMARKS:
210300Z POSITION NEAR 18.4N 145.0E.
TROPICAL STORM (TS) 13W (THIRTEEN), LOCATED APPROXIMATELY 190 NM
NORTH OF SAIPAN, HAS TRACKED WEST-SOUTHWESTWARD AT 04 KNOTS OVER THE
PAST SIX HOURS. JUSTIFICATION FOR RELOCATION: POSITION RELOCATED
SOUTHWARD BASED ON NEWLY AVAILABLE MULTISPECTRAL AND MICROWAVE
SATELLITE IMAGERY. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 210000Z IS 12
FEET. NEXT WARNINGS AT 210900Z, 211500Z, 212100Z AND 220300Z.//
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WDPN32 PGTW 200300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W (THIRTEEN) WARNING
NR 04//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
A. TROPICAL STORM (TS) 13W (THIRTEEN), LOCATED APPROXIMATELY 190
NM NORTH OF SAIPAN, HAS TRACKED WEST-SOUTHWESTWARD AT 04 KNOTS OVER
THE PAST SIX HOURS. THE CYCLONE HAS BEEN RELOCATED SLIGHTLY TO THE
SOUTH BASED ON ANALYSIS OF RECENT MICROWAVE DATA AND MULTISPECTRAL
SATELLITE IMAGERY, INCLUDING A 202332Z PGTW SATELLITE FIX. THE
CURRENT INTENSITY OF 35 KNOTS IS CONSISTENT WITH A DVORAK T-NUMBER
VALUE OF 2.5 FROM PGTW. TROPICAL STORM 13W IS TRACKING SLOWLY WEST-
SOUTHWESTWARD UNDER THE INFLUENCE OF A WEAK LOW TO MIDDLE LEVEL
SUBTROPICAL STEERING RIDGE TO THE NORTH. DEEP CONVECTION IS
PERSISTING ALONG A CONVERGENT BAND ON THE SOUTHERN PERIPHERY OF THE
LOW LEVEL CIRCULATION CENTER (LLCC). AN ANTICYCLONE ALOFT IS
EXPANDING AS A TROPICAL UPPER TROPOSPHERIC TROUGH TO THE NORTH
REORIENTS, ALLOWING OUTFLOW TO IMPROVE AND REDUCING VERTICAL WIND
SHEAR OVER THE CYCLONE.
3. FORECAST REASONING
A. SINCE THE FIRST PROGNOSTIC REASONING MESSAGE WAS ISSUED, THE
TAU 0 TO TAU 48 FORECAST TRACK HAS BEEN SHIFTED SLIGHTLY EQUATORWARD
GIVEN CURRENT TRENDS IN STORM MOTION, AND THE TAU 120 FORECAST HAS
BEEN SHIFTED WESTWARD TO REFLECT THE ANTICIPATED EVOLUTION OF A MORE
MERIDIONALLY-ORIENTED STEERING PATTERN. THE PEAK FORECAST INTENSITY
HAS ALSO BEEN INCREASED TO ACCOUNT FOR FAVORABLE ALONG-TRACK UPPER-
LEVEL SUPPORT.
B. GENERALLY WESTWARD MOTION IS EXPECTED TO CONTINUE THROUGH TAU
48 AS THE CURRENT STEERING REGIME PERSISTS. THEREAFTER, AN
APPROACHING MID-LATITUDE TROUGH WILL WEAKEN THE RIDGE TO THE NORTH,
ALLOWING THE CYCLONE TO MAKE A POLEWARD TURN. THE CYCLONE IS
EXPECTED TO INTENSIFY SLOWLY THROUGH TAU 36 AS THE UPPER LEVEL
PATTERN REORIENTS AND VERTICAL WIND SHEAR CONTINUES TO RELAX. AS THE
SYSTEM ROUNDS THE STEERING RIDGE AXIS BETWEEN TAU 36 AND TAU 72,
VERY FAVORABLE UPPER LEVEL OUTFLOW AND LOW VERTICAL WIND SHEAR WILL
ENABLE MORE RAPID DEVELOPMENT. THE NUMERICAL MODEL TRACK GUIDANCE IS
IN GOOD AGREEMENT THROUGH TAU 72 WITH THE EXCEPTION OF THE GFS,
WHICH DEPICTS AND SUDDEN AND UNREALISTIC WEAKENING OF THE CURRENT
STEERING RIDGE AND A RESULTING POLEWARD TRACK. THE CURRENT FORECAST
LIES CLOSE TO THE MODEL CONSENSUS DURING THIS PERIOD.
C. BETWEEN TAU 72 AND TAU 120, TS 13W WILL ACCELERATE POLEWARD
AND UNDERGO EXTRATROPICAL TRANSITION IN THE GRADIENT BETWEEN THE MID-
LATITUDE TROUGH TO THE WEST AND A SUBTROPICAL RIDGE TO THE EAST.
DURING EXTRATROPICAL TRANSITION, THE CYCLONE WILL REMAIN QUITE
INTENSE, AS STRONG UPPER LEVEL DIFFLUENCE AND A SHARP TEMPERATURE
GRADIENT ASSOCIATED WITH THE APPROACHING TROUGH PROVIDE A STRONG
BAROCLINIC DEVELOPMENT MECHANISM. BETWEEN TAU 72 AND TAU 120, THE
NUMERICAL MODEL SOLUTIONS DIVERGE SLIGHTLY, WITH THE ECMWF SHOWING A
MORE MERIDIONALLY-ORIENTED TROUGH-RIDGE PATTERN AND RESULTANT TRACK
THAN THE GFS, NOGAPS, AND UKMET MODELS. THIS FORECAST LIES SLIGHTLY
WEST OF THE FORECAST TRACK CONSENSUS IN THE LATER TAUS TO ACCOUNT
FOR THIS POSSIBILITY AND MAY NEED TO BE ADJUSTED FURTHER WESTWARD IF
THE SYNOPTIC PATTERN SHIFTS TOWARD THE ECMWF DEPICTION.//
NNNN
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W (THIRTEEN) WARNING
NR 04//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
A. TROPICAL STORM (TS) 13W (THIRTEEN), LOCATED APPROXIMATELY 190
NM NORTH OF SAIPAN, HAS TRACKED WEST-SOUTHWESTWARD AT 04 KNOTS OVER
THE PAST SIX HOURS. THE CYCLONE HAS BEEN RELOCATED SLIGHTLY TO THE
SOUTH BASED ON ANALYSIS OF RECENT MICROWAVE DATA AND MULTISPECTRAL
SATELLITE IMAGERY, INCLUDING A 202332Z PGTW SATELLITE FIX. THE
CURRENT INTENSITY OF 35 KNOTS IS CONSISTENT WITH A DVORAK T-NUMBER
VALUE OF 2.5 FROM PGTW. TROPICAL STORM 13W IS TRACKING SLOWLY WEST-
SOUTHWESTWARD UNDER THE INFLUENCE OF A WEAK LOW TO MIDDLE LEVEL
SUBTROPICAL STEERING RIDGE TO THE NORTH. DEEP CONVECTION IS
PERSISTING ALONG A CONVERGENT BAND ON THE SOUTHERN PERIPHERY OF THE
LOW LEVEL CIRCULATION CENTER (LLCC). AN ANTICYCLONE ALOFT IS
EXPANDING AS A TROPICAL UPPER TROPOSPHERIC TROUGH TO THE NORTH
REORIENTS, ALLOWING OUTFLOW TO IMPROVE AND REDUCING VERTICAL WIND
SHEAR OVER THE CYCLONE.
3. FORECAST REASONING
A. SINCE THE FIRST PROGNOSTIC REASONING MESSAGE WAS ISSUED, THE
TAU 0 TO TAU 48 FORECAST TRACK HAS BEEN SHIFTED SLIGHTLY EQUATORWARD
GIVEN CURRENT TRENDS IN STORM MOTION, AND THE TAU 120 FORECAST HAS
BEEN SHIFTED WESTWARD TO REFLECT THE ANTICIPATED EVOLUTION OF A MORE
MERIDIONALLY-ORIENTED STEERING PATTERN. THE PEAK FORECAST INTENSITY
HAS ALSO BEEN INCREASED TO ACCOUNT FOR FAVORABLE ALONG-TRACK UPPER-
LEVEL SUPPORT.
B. GENERALLY WESTWARD MOTION IS EXPECTED TO CONTINUE THROUGH TAU
48 AS THE CURRENT STEERING REGIME PERSISTS. THEREAFTER, AN
APPROACHING MID-LATITUDE TROUGH WILL WEAKEN THE RIDGE TO THE NORTH,
ALLOWING THE CYCLONE TO MAKE A POLEWARD TURN. THE CYCLONE IS
EXPECTED TO INTENSIFY SLOWLY THROUGH TAU 36 AS THE UPPER LEVEL
PATTERN REORIENTS AND VERTICAL WIND SHEAR CONTINUES TO RELAX. AS THE
SYSTEM ROUNDS THE STEERING RIDGE AXIS BETWEEN TAU 36 AND TAU 72,
VERY FAVORABLE UPPER LEVEL OUTFLOW AND LOW VERTICAL WIND SHEAR WILL
ENABLE MORE RAPID DEVELOPMENT. THE NUMERICAL MODEL TRACK GUIDANCE IS
IN GOOD AGREEMENT THROUGH TAU 72 WITH THE EXCEPTION OF THE GFS,
WHICH DEPICTS AND SUDDEN AND UNREALISTIC WEAKENING OF THE CURRENT
STEERING RIDGE AND A RESULTING POLEWARD TRACK. THE CURRENT FORECAST
LIES CLOSE TO THE MODEL CONSENSUS DURING THIS PERIOD.
C. BETWEEN TAU 72 AND TAU 120, TS 13W WILL ACCELERATE POLEWARD
AND UNDERGO EXTRATROPICAL TRANSITION IN THE GRADIENT BETWEEN THE MID-
LATITUDE TROUGH TO THE WEST AND A SUBTROPICAL RIDGE TO THE EAST.
DURING EXTRATROPICAL TRANSITION, THE CYCLONE WILL REMAIN QUITE
INTENSE, AS STRONG UPPER LEVEL DIFFLUENCE AND A SHARP TEMPERATURE
GRADIENT ASSOCIATED WITH THE APPROACHING TROUGH PROVIDE A STRONG
BAROCLINIC DEVELOPMENT MECHANISM. BETWEEN TAU 72 AND TAU 120, THE
NUMERICAL MODEL SOLUTIONS DIVERGE SLIGHTLY, WITH THE ECMWF SHOWING A
MORE MERIDIONALLY-ORIENTED TROUGH-RIDGE PATTERN AND RESULTANT TRACK
THAN THE GFS, NOGAPS, AND UKMET MODELS. THIS FORECAST LIES SLIGHTLY
WEST OF THE FORECAST TRACK CONSENSUS IN THE LATER TAUS TO ACCOUNT
FOR THIS POSSIBILITY AND MAY NEED TO BE ADJUSTED FURTHER WESTWARD IF
THE SYNOPTIC PATTERN SHIFTS TOWARD THE ECMWF DEPICTION.//
NNNN
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WTPQ21 RJTD 210300
RSMC TROPICAL CYCLONE ADVISORY
NAME TD
ANALYSIS
PSTN 210300UTC 18.1N 145.1E POOR
MOVE NNW SLOWLY
PRES 1006HPA
MXWD 030KT
GUST 045KT
FORECAST
24HF 220300UTC 19.4N 142.8E 120NM 70%
MOVE WNW 06KT
PRES 998HPA
MXWD 035KT
GUST 050KT =
000
ATPQ40 PGUM 210257
SIMGUM
SATELLITE INTERPRETATION MESSAGE
NATIONAL WEATHER SERVICE TIYAN GU
100 PM CHST TUE SEP 21 2010
WESTERN NORTH PACIFIC BETWEEN EQUATOR AND 25N FROM 130E TO 180.
TROPICAL STORM 13W IS CENTERED JUST NORTHWEST OF AGRIHAN NEAR
18N146E...AND IS MOVING TO THE NORTHWEST AT 7 MPH WITH MAXIMUM
SUSTAINED WINDS OF 40 MPH. NUMEROUS SHOWERS AND SCATTERED
THUNDERSTORMS ARE FOUND AROUND THE CENTER AND ACROSS THE NORTHERN
MARIANAS BETWEEN 14N AND 20N FROM 140E TO 149E. TRADE-WIND
CONVERGENCE ALONG THE EASTERN EDGE OF 13W IS PRODUCING SCATTERED
SHOWERS AND THUNDERSTORMS BETWEEN 15N AND 24N FROM 151E TO 155E. FOR
FURTHER INFORMATION ON TROPICAL STORM 13W...REFER TO JTWC BULLETINS
UNDER WMO HEADER WTPN32 PGTW AND NATIONAL WEATHER SERVICE PUBLIC
ADVISORIES UNDER WMO HEADER WTPQ32 PGUM.
TXPN28 KNES 210346
SIMWIR
A. 13W (NONAME)
B. 21/0232Z
C. 18.0N
D. 145.2E
E. FIVE/MTSAT
F. T2.5/2.5/D1.0/24HRS
G. IR/EIR/VIS
H. REMARKS...DT OF 2.5 BASED ON .5 VIS BANDING. MET AND PT AGREE.
FT BASED ON MET.
I. ADDL POSITIONS
NIL
...LIDDICK
=
RSMC TROPICAL CYCLONE ADVISORY
NAME TD
ANALYSIS
PSTN 210300UTC 18.1N 145.1E POOR
MOVE NNW SLOWLY
PRES 1006HPA
MXWD 030KT
GUST 045KT
FORECAST
24HF 220300UTC 19.4N 142.8E 120NM 70%
MOVE WNW 06KT
PRES 998HPA
MXWD 035KT
GUST 050KT =
000
ATPQ40 PGUM 210257
SIMGUM
SATELLITE INTERPRETATION MESSAGE
NATIONAL WEATHER SERVICE TIYAN GU
100 PM CHST TUE SEP 21 2010
WESTERN NORTH PACIFIC BETWEEN EQUATOR AND 25N FROM 130E TO 180.
TROPICAL STORM 13W IS CENTERED JUST NORTHWEST OF AGRIHAN NEAR
18N146E...AND IS MOVING TO THE NORTHWEST AT 7 MPH WITH MAXIMUM
SUSTAINED WINDS OF 40 MPH. NUMEROUS SHOWERS AND SCATTERED
THUNDERSTORMS ARE FOUND AROUND THE CENTER AND ACROSS THE NORTHERN
MARIANAS BETWEEN 14N AND 20N FROM 140E TO 149E. TRADE-WIND
CONVERGENCE ALONG THE EASTERN EDGE OF 13W IS PRODUCING SCATTERED
SHOWERS AND THUNDERSTORMS BETWEEN 15N AND 24N FROM 151E TO 155E. FOR
FURTHER INFORMATION ON TROPICAL STORM 13W...REFER TO JTWC BULLETINS
UNDER WMO HEADER WTPN32 PGTW AND NATIONAL WEATHER SERVICE PUBLIC
ADVISORIES UNDER WMO HEADER WTPQ32 PGUM.
TXPN28 KNES 210346
SIMWIR
A. 13W (NONAME)
B. 21/0232Z
C. 18.0N
D. 145.2E
E. FIVE/MTSAT
F. T2.5/2.5/D1.0/24HRS
G. IR/EIR/VIS
H. REMARKS...DT OF 2.5 BASED ON .5 VIS BANDING. MET AND PT AGREE.
FT BASED ON MET.
I. ADDL POSITIONS
NIL
...LIDDICK
=
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- StormingB81
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Impressive convection along the main circulation, seems to be a CDO if I'm not mistaken. I wouldn't be surprised if this undergoes RI.
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The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.
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Re: WPAC: Tropical Depression (JTWC: TS 13W)
I think it will not, dhoeze. The models are pretty much in agreement with this being captured by the trough as it accelerates N-NE. However, this would create a severe extratropical system as it marches towards the NE...could affect the Aleutian.
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The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.
- StormingB81
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Re: WPAC: Tropical Depression (JTWC: TS 13W)
Still think it will be picked up by that trough, but wow it really is threading the needle on it. If it does not it will be one massive change in forecast track. Any how I think it will go a little W than the current track. Probably get some precip from the outer rain bands over the tokyo area.
Below is my thought on the track. Also I got a new video at westernpacificweather.com ..
Below is my thought on the track. Also I got a new video at westernpacificweather.com ..
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This probably will be another strong system in a few days time, finally starting to get some more decent systems again in the WPAC after pretty much nothing of note...
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Personal Forecast Disclaimer:
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The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products
- StormingB81
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- StormingB81
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- WestPACMet
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I think there will be a little more time than you think, to the west high pressure is dominating, if it does loose support from the trough it will likely linger in the area for a period of time. (my thoughts)
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- StormingB81
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