Tropical Depression Chebi - spinning down in South China Sea
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Tropical Depression Chebi - spinning down in South China Sea
WWJP25 RJTD 080600
WARNING AND SUMMARY 080600.
WARNING VALID 090600.
WARNING IS UPDATED EVERY 6 HOURS.
SUMMARY.
TROPICAL DEPRESSION 1008 HPA AT 16N 136E WNW SLOWLY.
HIGH 1024 HPA AT 31N 137E EAST 30 KT.
HIGH 1024 HPA AT 35N 149E EAST 25 KT.
HIGH 1032 HPA AT 41N 175E SE 15 KT.
JAPAN METEOROLOGICAL AGENCY.=
The JTWC has also issued a TCFA on this system, dubbed 90W. If FNMOC was right (for a while it showed the same sat pics for 90W and 90C), this is a continuation of the system 90C (which was overshadowed, really, by 91C).
WARNING AND SUMMARY 080600.
WARNING VALID 090600.
WARNING IS UPDATED EVERY 6 HOURS.
SUMMARY.
TROPICAL DEPRESSION 1008 HPA AT 16N 136E WNW SLOWLY.
HIGH 1024 HPA AT 31N 137E EAST 30 KT.
HIGH 1024 HPA AT 35N 149E EAST 25 KT.
HIGH 1032 HPA AT 41N 175E SE 15 KT.
JAPAN METEOROLOGICAL AGENCY.=
The JTWC has also issued a TCFA on this system, dubbed 90W. If FNMOC was right (for a while it showed the same sat pics for 90W and 90C), this is a continuation of the system 90C (which was overshadowed, really, by 91C).
Last edited by Chacor on Mon Nov 13, 2006 2:57 am, edited 8 times in total.
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- WesternPacificWeather.com
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Aslkahuna wrote:A latitude of 16N is a bit north for a storm out at 136E to hit the Philippines since the recurvature latitude is usually around 18-19 in November. Usually storms that hit the Philippines in November originate further south than 16N.
Steve

JTWC doesn't seem to think so, heading directly west!
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WDPN31 PGTW 090300
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W WARNING NR 01//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 090000Z TO 120000Z NOV 2006.
A. TROPICAL DEPRESSION (TD) 23W, LOCATED APPROXIMATELY 675 NM
EAST
OF MANILA, PHILIPPINES, HAS TRACKED WEST AT 09 KNOTS OVER THE PAST
SIX
HOURS. A CLOSED CIRCULATION WAS NOT EVIDENT ON A 082102Z QUIKSCAT
PASS, BUT RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY INDICATES
WESTERLY WINDS ON THE SOUTHERN PERIPHERY OF 23W, WRAPPING INTO A LOW-
LEVEL CIRCULATION CENTER (LLCC).
B. TD 23W IS TRACKING WESTWARD, SOUTH OF THE SUBTROPICAL RIDGE
(STR). UPPER LEVEL ANALYSIS REVEALS A STRONG POLEWARD OUTFLOW CHANNEL
INDUCED BETWEEN AN ANTICYCLONE ANCHORED NORTH OF THE MARIANAS AND A
STRONG MIDLATITUDE JET STREAM SOUTH OF JAPAN. THE DISTURBANCE CUR-
RENTLY LACKS SIGNIFICANT EQUATORWARD OUTFLOW DUE TO ITS LOCATION ON
THE SOUTHWEST PERIPHERY OF THE ANTICYCLONE. THE INTENSITY OF 23W WILL
PLAY A SIGNIFICANT ROLE IN ITS FORECAST TRACK PAST TAU 48. A DEEP
MID-
LATITUDE TROUGH WILL CREATE A BREAK IN THE SUBTROPICAL RIDGE NORTH
OF
LUZON AROUND TAU 60, BUT THE SYSTEM IS NOT FORECAST TO HAVE
SUFFICIENT
VERTICAL DEPTH TO INTERACT WITH THE MIDLATITUDE ENVIRONMENT. WBAR IS
THE LONE AID DEPICTING A RECURVATURE SCENARIO THROUGH THIS BREAK IN
THE STR. THE REMAINING AVAILABLE AIDS INDICATE A WEAKER STORM
STEERED
AT LOWER LEVELS. THIS FORECAST IS BASED ON A CONSENSUS OF THE AVAIL-
ABLE DYNAMIC AIDS, WITH LESS EMPHASIS ON WBAR. DUE TO THE UNCERTAINTY
IN THE INTENSITY FORECAST BEYOND TAU 48, CONFIDENCE IN THE FORECAST
TRACK IS LOW AT THIS TIME.
C. TD 22W EXPERIENCED INCREASED CONVECTION AROUND THE LLCC OVER
THE
PAST SIX HOURS, WITH THE STRONG POLEWARD OUTFLOW CHANNEL ENHANCING
INTENSIFICATION. THE CYCLONE IS CURRENTLY FORECAST TO MOVE TOWARD A
COOLER AIR MASS OFF THE COAST OF THE ASIAN CONTINENT. ADDITIONALLY,
THE LACK OF AN EQUATORWARD OUTFLOW CHANNEL IS CURRENTLY INHIBITING
RAPID DEVELOPMENT. IT SHOULD BE NOTED HOWEVER, THAT THE AIDS DEPICT A
MIGRATION OF THE 200 MB ANTICYCLONE WESTWARD, AND BEYOND TAU 48,
EQUATORWARD OUTFLOW COULD BE ENHANCED ON ITS SOUTHEASTERN PERIPHERY.
D. FORECAST WIND RADII CRITERIA ARE BASED ON CLIMATOLOGY FOR AN
AVERAGE SIZED SYSTEM.
FORECAST TEAM: BRAVO//
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W WARNING NR 01//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 090000Z TO 120000Z NOV 2006.
A. TROPICAL DEPRESSION (TD) 23W, LOCATED APPROXIMATELY 675 NM
EAST
OF MANILA, PHILIPPINES, HAS TRACKED WEST AT 09 KNOTS OVER THE PAST
SIX
HOURS. A CLOSED CIRCULATION WAS NOT EVIDENT ON A 082102Z QUIKSCAT
PASS, BUT RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY INDICATES
WESTERLY WINDS ON THE SOUTHERN PERIPHERY OF 23W, WRAPPING INTO A LOW-
LEVEL CIRCULATION CENTER (LLCC).
B. TD 23W IS TRACKING WESTWARD, SOUTH OF THE SUBTROPICAL RIDGE
(STR). UPPER LEVEL ANALYSIS REVEALS A STRONG POLEWARD OUTFLOW CHANNEL
INDUCED BETWEEN AN ANTICYCLONE ANCHORED NORTH OF THE MARIANAS AND A
STRONG MIDLATITUDE JET STREAM SOUTH OF JAPAN. THE DISTURBANCE CUR-
RENTLY LACKS SIGNIFICANT EQUATORWARD OUTFLOW DUE TO ITS LOCATION ON
THE SOUTHWEST PERIPHERY OF THE ANTICYCLONE. THE INTENSITY OF 23W WILL
PLAY A SIGNIFICANT ROLE IN ITS FORECAST TRACK PAST TAU 48. A DEEP
MID-
LATITUDE TROUGH WILL CREATE A BREAK IN THE SUBTROPICAL RIDGE NORTH
OF
LUZON AROUND TAU 60, BUT THE SYSTEM IS NOT FORECAST TO HAVE
SUFFICIENT
VERTICAL DEPTH TO INTERACT WITH THE MIDLATITUDE ENVIRONMENT. WBAR IS
THE LONE AID DEPICTING A RECURVATURE SCENARIO THROUGH THIS BREAK IN
THE STR. THE REMAINING AVAILABLE AIDS INDICATE A WEAKER STORM
STEERED
AT LOWER LEVELS. THIS FORECAST IS BASED ON A CONSENSUS OF THE AVAIL-
ABLE DYNAMIC AIDS, WITH LESS EMPHASIS ON WBAR. DUE TO THE UNCERTAINTY
IN THE INTENSITY FORECAST BEYOND TAU 48, CONFIDENCE IN THE FORECAST
TRACK IS LOW AT THIS TIME.
C. TD 22W EXPERIENCED INCREASED CONVECTION AROUND THE LLCC OVER
THE
PAST SIX HOURS, WITH THE STRONG POLEWARD OUTFLOW CHANNEL ENHANCING
INTENSIFICATION. THE CYCLONE IS CURRENTLY FORECAST TO MOVE TOWARD A
COOLER AIR MASS OFF THE COAST OF THE ASIAN CONTINENT. ADDITIONALLY,
THE LACK OF AN EQUATORWARD OUTFLOW CHANNEL IS CURRENTLY INHIBITING
RAPID DEVELOPMENT. IT SHOULD BE NOTED HOWEVER, THAT THE AIDS DEPICT A
MIGRATION OF THE 200 MB ANTICYCLONE WESTWARD, AND BEYOND TAU 48,
EQUATORWARD OUTFLOW COULD BE ENHANCED ON ITS SOUTHEASTERN PERIPHERY.
D. FORECAST WIND RADII CRITERIA ARE BASED ON CLIMATOLOGY FOR AN
AVERAGE SIZED SYSTEM.
FORECAST TEAM: BRAVO//
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- senorpepr
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Personally, I think JTWC's assessment is too westward. After studying a few models myself, I tend to think PAGASA's forecast is probably closer to correct, although it wouldn't surprise me if that was too west/south.
Steve's comments are something to take note of. He probably has more experience with Filipino tropical cyclones than all of the forecasters at JTWC combined. (Although there may be a rouge civilian or two there that might have some knowledge)
Steve's comments are something to take note of. He probably has more experience with Filipino tropical cyclones than all of the forecasters at JTWC combined. (Although there may be a rouge civilian or two there that might have some knowledge)
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senorpepr wrote:Personally, I think JTWC's assessment is too westward. After studying a few models myself, I tend to think PAGASA's forecast is probably closer to correct, although it wouldn't surprise me if that was too west/south.
PAGASA's current forecast, by the way...

Their original track had it more northward, hitting southern Taiwan.
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- Aslkahuna
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It's all going to depend upon the intensity. If the storm remains below typhoon intensity, then it will be steered by a lower level flow. If it becomes a typhoon then the internal forces will add a northward component to the track and it will become steered by deeper layer flow and could cross the magic 18-19N Latitude above which recurvature becomes more likely. If it bombs into a Super, ti will take off NW and then mostly north before it reaches Luzon. If it does remain a TS then the main effect will be rain and then it will head for the death trap of the SCS.
Steve
Steve
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- P.K.
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0620 has formed.
WTPQ20 RJTD 091200
RSMC TROPICAL CYCLONE ADVISORY
NAME TS 0620 CHEBI (0620) UPGRADED FROM TD
ANALYSIS
PSTN 091200UTC 15.9N 130.1E FAIR
MOVE W 11KT
PRES 1000HPA
MXWD 035KT
30KT 100NM
FORECAST
24HF 101200UTC 15.5N 124.7E 80NM 70%
MOVE W 13KT
PRES 998HPA
MXWD 035KT
48HF 111200UTC 15.1N 120.5E 150NM 70%
MOVE W 10KT
PRES 996HPA
MXWD 040KT
72HF 121200UTC 14.6N 116.9E 220NM 70%
MOVE W 08KT
PRES 996HPA
MXWD 040KT =
WTPQ20 RJTD 091200
RSMC TROPICAL CYCLONE ADVISORY
NAME TS 0620 CHEBI (0620) UPGRADED FROM TD
ANALYSIS
PSTN 091200UTC 15.9N 130.1E FAIR
MOVE W 11KT
PRES 1000HPA
MXWD 035KT
30KT 100NM
FORECAST
24HF 101200UTC 15.5N 124.7E 80NM 70%
MOVE W 13KT
PRES 998HPA
MXWD 035KT
48HF 111200UTC 15.1N 120.5E 150NM 70%
MOVE W 10KT
PRES 996HPA
MXWD 040KT
72HF 121200UTC 14.6N 116.9E 220NM 70%
MOVE W 08KT
PRES 996HPA
MXWD 040KT =
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- P.K.
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The ICAO TC advisory has Chebi forecast to get upgraded to a STS within 12 hours.
RSMC TROPICAL CYCLONE ADVISORY
NAME TS 0620 CHEBI (0620)
ANALYSIS
PSTN 091800UTC 16.1N 128.6E FAIR
MOVE W 14KT
PRES 994HPA
MXWD 045KT
30KT 140NM NORTHEAST 100NM SOUTHWEST
FORECAST
24HF 101800UTC 15.3N 123.3E 80NM 70%
MOVE W 12KT
PRES 985HPA
MXWD 050KT
48HF 111800UTC 14.8N 119.2E 150NM 70%
MOVE W 09KT
PRES 980HPA
MXWD 055KT
72HF 121800UTC 13.8N 114.5E 220NM 70%
MOVE WSW 11KT
PRES 975HPA
MXWD 060KT =
RSMC TROPICAL CYCLONE ADVISORY
NAME TS 0620 CHEBI (0620)
ANALYSIS
PSTN 091800UTC 16.1N 128.6E FAIR
MOVE W 14KT
PRES 994HPA
MXWD 045KT
30KT 140NM NORTHEAST 100NM SOUTHWEST
FORECAST
24HF 101800UTC 15.3N 123.3E 80NM 70%
MOVE W 12KT
PRES 985HPA
MXWD 050KT
48HF 111800UTC 14.8N 119.2E 150NM 70%
MOVE W 09KT
PRES 980HPA
MXWD 055KT
72HF 121800UTC 13.8N 114.5E 220NM 70%
MOVE WSW 11KT
PRES 975HPA
MXWD 060KT =
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- WesternPacificWeather.com
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!
Interesting JMA update. It's now STS Chebi and expected to be a typhoon within 24 hours. After that they expect Checi to intensify to 70kts whilst over the southern SCS.
Issued at 00:00 UTC 10 Nov 2006RSMC TROPICAL CYCLONE ADVISORY
NAME STS 0620 CHEBI (0620) UPGRADED FROM TS
ANALYSIS
PSTN 100000UTC 16.1N 127.2E GOOD
MOVE W 13KT
PRES 985HPA
MXWD 055KT
50KT 30NM
30KT 140NM NORTH 100NM SOUTH
FORECAST
24HF 110000UTC 15.0N 121.7E 80NM 70%
MOVE WSW 13KT
PRES 970HPA
MXWD 065KT
48HF 120000UTC 14.1N 118.3E 150NM 70%
MOVE WSW 08KT
PRES 970HPA
MXWD 065KT
72HF 130000UTC 13.7N 113.9E 220NM 70%
MOVE W 10KT
PRES 965HPA
MXWD 070KT
Issued at 00:00 UTC 10 Nov 2006RSMC TROPICAL CYCLONE ADVISORY
NAME STS 0620 CHEBI (0620) UPGRADED FROM TS
ANALYSIS
PSTN 100000UTC 16.1N 127.2E GOOD
MOVE W 13KT
PRES 985HPA
MXWD 055KT
50KT 30NM
30KT 140NM NORTH 100NM SOUTH
FORECAST
24HF 110000UTC 15.0N 121.7E 80NM 70%
MOVE WSW 13KT
PRES 970HPA
MXWD 065KT
48HF 120000UTC 14.1N 118.3E 150NM 70%
MOVE WSW 08KT
PRES 970HPA
MXWD 065KT
72HF 130000UTC 13.7N 113.9E 220NM 70%
MOVE W 10KT
PRES 965HPA
MXWD 070KT
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- Aslkahuna
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Climatologically speakig this is not a usual track for this time in November but in looking at the H5 pattern over WPAC. the pattern is more typical of October than November thus the more westward track. One thing I'm wondering about is why JMA is insisting on maintaining intensity across Luzon and then increasing it in the SCS on a SW track-that would be even more unusual. Ah well, that's why forecasting TC's is so interesting.
Steve
Steve
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- Aslkahuna
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Deja vu-sort of. The track across Luzon reminds me of another November storm that defied climatology and pursued a due west track below 16N to Luzon turning SW directly over Clark AB on November 28,1974. Thereafter, the storm further defied climo by turning north and becoming the strongest storm on record in the northern portions of the SCS and the latest storm to hit Hong Kong which is did in early December. That was typhoon Irma. Irma, BTW, was the last of a barrage of 6 typhoons and one Tropical Storm that hit Luzon between October 11th and November 28th. November 28, 1974 was also Thanksgiving Day. The difference being that Irma was a much larger and right now more intense storm than Chebi.
Steve
Steve
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Aslkahuna wrote:Deja vu-sort of. The track across Luzon reminds me of another November storm that defied climatology and pursued a due west track below 16N to Luzon turning SW directly over Clark AB on November 28,1974. Thereafter, the storm further defied climo by turning north and becoming the strongest storm on record in the northern portions of the SCS and the latest storm to hit Hong Kong which is did in early December. That was typhoon Irma. Irma, BTW, was the last of a barrage of 6 typhoons and one Tropical Storm that hit Luzon between October 11th and November 28th. November 28, 1974 was also Thanksgiving Day. The difference being that Irma was a much larger and right now more intense storm than Chebi.
Steve
1974 was odd because no super typhoons formed. However, I have read that some suspect Typhoon Gloria may have reached super typhoon status prior to landfall on the Philippines.
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The bottom is really dropping out on Chebi. Raw ADT numbers are about 5.3 and dropping quickly (corresponding to an intensity of ~100knots). I would venture to guess that Chebi is even stronger than that by the latest satellite appearance. Could very well be a repeat of Cimaron in terms of the intensification and unfortunately for the Phillipines.
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JMA ups it from 55 kt 985 hPa to 95 kt 945 hPa - a 40 hPa drop in three hours. Absolutely amazing, and potentially deadly.
RSMC TROPICAL CYCLONE ADVISORY
NAME TY 0620 CHEBI (0620) UPGRADED FROM STS
ANALYSIS
PSTN 100600UTC 16.2N 125.6E GOOD
MOVE W 15KT
PRES 945HPA
MXWD 095KT
50KT 50NM
30KT 150NM NORTH 130NM SOUTH
FORECAST
24HF 110600UTC 15.1N 120.7E 80NM 70%
MOVE WSW 12KT
PRES 945HPA
MXWD 095KT
48HF 120600UTC 14.2N 116.7E 150NM 70%
MOVE WSW 09KT
PRES 940HPA
MXWD 095KT
72HF 130600UTC 13.9N 112.2E 220NM 70%
MOVE W 10KT
PRES 940HPA
MXWD 095KT
RSMC TROPICAL CYCLONE ADVISORY
NAME TY 0620 CHEBI (0620) UPGRADED FROM STS
ANALYSIS
PSTN 100600UTC 16.2N 125.6E GOOD
MOVE W 15KT
PRES 945HPA
MXWD 095KT
50KT 50NM
30KT 150NM NORTH 130NM SOUTH
FORECAST
24HF 110600UTC 15.1N 120.7E 80NM 70%
MOVE WSW 12KT
PRES 945HPA
MXWD 095KT
48HF 120600UTC 14.2N 116.7E 150NM 70%
MOVE WSW 09KT
PRES 940HPA
MXWD 095KT
72HF 130600UTC 13.9N 112.2E 220NM 70%
MOVE W 10KT
PRES 940HPA
MXWD 095KT
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