WPAC: SONCA - Tropical Depression

[euro6208]

WDPN32 PGTW 222100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 08W (EIGHT)
WARNING NR 08/
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 08W (EIGHT), LOCATED APPROXIMATELY 74 NM
EAST-SOUTHEAST OF HAINAN, CHINA, HAS TRACKED WESTWARD AT 05 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS A COMPACT SYSTEM WITH WEAK BUT FLARING CONVECTION
THAT IS OFFSET WESTWARD FROM THE LOW LEVEL CIRCULATION (LLC). A
221821Z 89GHZ GPM PASS SHOWS A PARTIALLY EXPOSED LLC ON THE EASTERN
EDGE OF ISOLATED DEEP CONVECTION. UPPER-LEVEL ANALYSIS INDICATES A
MARGINALLY-FAVORABLE ENVIRONMENT WITH LOW TO MODERATE VERTICAL WIND
SHEAR (15-20 KNOTS) OFFSET BY GOOD EQUATORWARD OUTFLOW AND WEAK
POLEWARD OUTFLOW. THE CURRENT INTENSITY IS ASSESSED AT 30 KNOTS
BASED ON DVORAK ESTIMATES OF T2.0 (30 KNOTS) FROM ALL AGENCIES. TD
08W IS TRACKING SLOWLY WESTWARD UNDER THE STEERING INFLUENCE OF THE
LOW-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TD 08W IS FORECAST TO CONTINUE TRACKING GENERALLY WEST-
NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR, MAKING
LANDFALL OVER HAINAN AFTER TAU 24. THE SYSTEM WILL MAINTAIN
INTENSITY THROUGH TAU 24, THEN WEAKEN AS IT TRACKS OVER HAINAN
ISLAND. DYNAMIC GUIDANCE IS IN POOR AGREEMENT, THEREFORE, THERE IS
LOW CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

Finally upgraded to a TS.

WDPN32 PGTW 230300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 08W (EIGHT) WARNING
NR 09/
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 08W (EIGHT), LOCATED APPROXIMATELY 212 NM EAST-
NORTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 03 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
AND A 221821Z GPM 89 GHZ IMAGE DEPICT A PARTIALLY EXPOSED LOW-LEVEL
CIRCULATION CENTER WITH FLARING DEEP CONVECTION, AND COOLING CLOUD-
TOPS, DISPLACED WEST OF THE SYSTEM. THE IMAGERY SUPPORTS THE INITIAL
POSITION WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 35 KNOTS IS
SUPPORTED BY DVORAK CURRENT INTENSITY ESTIMATES OF T2.5 (35 KNOTS)
FROM PGTW AND KNES. UPPER-LEVEL ANALYSIS INDICATES A MARGINALLY-
FAVORABLE ENVIRONENT WITH WEAK OUTFLOW AND LIGHT-MODERATE (15-20
KNOTS) VERTICAL WIND SHEAR. TS 08W IS TRACKING SLOWLY WESTWARD UNDER
THE STEERING INFLUENCE OF A LOW-LEVEL STR POSITIONED TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TD 08W IS FORECAST TO CONTINUE TRACKING GENERALLY WEST-
NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR, MAKING
LANDFALL OVER HAINAN AFTER TAU 36. THE SYSTEM WILL MAINTAIN
INTENSITY THROUGH TAU 24, THEN WEAKEN AS IT TRACKS OVER HAINAN
ISLAND. DYNAMIC MODEL GUIDANCE IS IN POOR AGREEMENT ON THE TRACK OF
08W WITH THE GFS/NAVGEM FURTHEST NORTH AND THE ECMWF/UKMET FURTHEST
SOUTH. THEREFORE, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST
TRACK.//
NNNN

[euro6208]

TPPN12 PGTW 230317

A. TROPICAL STORM 08W (SE OF HAINAN)

B. 23/0250Z

C. 17.52N

D. 111.42E

E. THREE/HMWRI8

F. T2.5/2.5/D0.5/24HRS STT: S0.0/03HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 19A/PBO XPSD LLCC/ANMTN. CNVCTN WRAPS .40 ON LOG10
SPIRAL YIELDING A DT OF 3.0. MET/PT ARE 2.5. DBO DT.

I. ADDITIONAL POSITIONS: NONE


ZOUFALY

[NotoSans]

Up to CI 2.5 from the JMA which means it is very possible for them to (finally) pull the trigger.

[NotoSans]

Upgraded to TS Sonca

WTPQ22 RJTD 230600
RSMC TROPICAL CYCLONE ADVISORY
NAME TS 1708 SONCA (1708) UPGRADED FROM TD
ANALYSIS
PSTN 230600UTC 17.6N 111.1E FAIR
MOVE ALMOST STATIONARY
PRES 1000HPA
MXWD 035KT
GUST 050KT
30KT 30NM
FORECAST
24HF 240600UTC 17.7N 110.3E 50NM 70%
MOVE ALMOST STATIONARY
PRES 1000HPA
MXWD 035KT
GUST 050KT
48HF 250600UTC 18.6N 107.7E 95NM 70%
MOVE WNW 07KT
PRES 1000HPA
MXWD 035KT
GUST 050KT
72HF 260600UTC 18.9N 103.7E 130NM 70% TROPICAL DEPRESSION =

[euro6208]

WDPN32 PGTW 230900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (SONCA)
WARNING NR 10//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 08W (SONCA), LOCATED APPROXIMATELY 197 NM EAST-
NORTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 03 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A COMPACT AND SYMMETRIC SYSTEM WITH FLARING CENTRAL
CONVECTION BEING DISPLACED SLIGHTLY TO THE WEST FROM THE LOW LEVEL
CIRCULATION CENTER(LLCC). THE INITIAL POSITION IS PLACED WITH GOOD
CONFIDENCE BASED ON RECENT SATELLITE FIXES AND A 220238Z METOP-B
ASCAT IMAGE. THE INITIAL INTENSITY IS ASSESSED AT 35 KNOTS BASED ON
MULTI-AGENCY CURRENT INTENSITY DVORAK ESTIMATES OF T2.5 (35 KNOTS).
THE AFOREMENTIONED ASCAT IMAGE SHOWS AN AREA OF 30 KNOT WINDS
ENCIRCLING THE LLCC WINDS BUT NOT EXTENDING MORE THAN 35 NM FROM THE
CENTER. ENVIRONMENTAL CONDITIONS ARE CURRENTLY MARGINAL AS EASTERLY
WIND SHEAR IS SLOWLY INCREASING UNDER VERY WARM (29 CELSIUS) SEA
SURFACE TEMPERATURES. THE DOMINANT STEERING RIDGE TO THE NORTH,
WHICH HAS PREVIOUSLY GUIDED TS 08W WESTWARD, HAS ERODED DUE TO THE
REMNANTS OF TS 10W PASSING TO THE NORTH. AS A RESULT TS 08W HAS
SLOWED DOWN CONSIDERABLY, TAKING A NEAR STATIONARY TRACK OVER THE
LAST 12 HOURS.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. THE NORTHERN STEERING RIDGE WILL BEGIN TO BUILD EXTENDING EAST
OF TS 08W, RESULTING IN A SLIGHT TURN NORTHWESTWARD OVER THE NEXT 12
HOURS. THE LLCC IS EXPECTED TO REMAIN CONSOLIDATED AS UNDER MARGINAL
MODERATE WIND SHEAR MAINTAINING A 35 KNOT INTENSITY BEFORE MAKING
LANDFALL OVER HAINAN. LAND INTERACTION WILL RAPIDLY DISRUPT THE LOW
LEVEL WINDS LEADING TO RAPID DISSIPATION BY TAU 48. THE REMNANTS OF
TS 08W IS EXPECTED TO CONTINUE TRACKING WESTWARD OVER THE GULF OF
TONKIN BUT REGENERATION IS UNLIKELY DUE TO UNFAVORABLE WIND SHEAR IN
THE REGION. DYNAMIC MODEL GUIDANCE SHOWS SIGNIFICANT SPREAD IN
POSSIBLE TRACKS DUE TO THE UNCERTAINTY OF THE BUILDING STEERING
RIDGE, LENDING LOW CONFIDENCE TO THE FORECAST TRACK.
NNNN

[doomhaMwx]

Up to 40kts by JTWC @ 00z...
Still possible that the system will first make landfall over the southern part of Hainan within the next 24hrs before crossing Vietnam's coast by tomorrow(Tuesday) evening or early Wednesday local date/time...

[euro6208]

WDPN32 PGTW 240900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (SONCA) WARNING
NR 14//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 08W (SONCA), LOCATED APPROXIMATELY 161 NM EAST-
NORTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 05 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS PULSATING CENTRAL CONVECTION BEING DISPLACED SLIGHTLY TO THE
WEST OF THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL
POSITION IS BASED ON RECENT SATELLITE FIXES WITH FAIR CONFIDENCE DUE
TO CONVECTIVE CLOUD TOPS OBSCURING THE LLCC. THE INITIAL INTENSITY
IS ASSESSED AT 40 KNOTS BASED ON MULTI-AGENCY DVORAK ESTIMATES
RANGING FROM T2.0 TO T3.0 (30 TO 45 KNOTS). ENVIRONMENTAL CONDITIONS
ARE CURRENTLY MARGINAL AS EASTERLY WIND SHEAR HAS RELAXED SOME OVER
THE LAST SIX HOURS AND WARM (29 CELSIUS) SEA SURFACE TEMPERATURES
PERSIST. CURRENTLY TS 08W IS TRACKING WESTWARD ALONG THE SOUTHERN
PERIPHERY OF A BUILDING DEEP-LAYER RIDGE TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. THE NORTHERN STEERING RIDGE WILL CONTINUE TO BUILD, STEERING
TS 08W WESTWARD FOR THE REMAINDER OF THE FORECAST. WIND SHEAR IS
EXPECTED TO REMAIN MARGINAL TO UNFAVORABLE, HOWEVER, THE STORM
MOTION WILL BE IN PHASE WITH THE SHEAR VECTOR. THIS COUPLED WITH
WARM SSTS IN THE REGION WILL FUEL FURTHER INTENSIFICATION, REACHING
A PEAK INTENSITY OF 50 KNOTS BY TAU 24. LANDFALL OVER VIETNAM IS
EXPECTED SOMETIME AROUND TAU 30, AND TS 08W WILL RAPIDLY DISSIPATE
OVER THE MOUNTAINOUS TERRAIN. FULL DISSIPATION IS EXPECTED BY TAU
48. DYNAMIC MODEL GUIDANCE HAS COME INTO MUCH BETTER AGREEMENT OVER
THE LAST COUPLE MODEL RUNS AS THE BUILDING STEERING RIDGE STARTS TO
EXERT INFLUENCE OVER THE SYSTEM. OVERALL THERE IS HIGH CONFIDENCE IN
THE FORECAST TRACK.//
NNNN

[euro6208]

WDPN32 PGTW 242100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (SONCA) WARNING
NR 16//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 08W (SONCA), LOCATED APPROXIMATELY 96 NM EAST-
NORTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 08 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
SHOWS PERSISTENT CENTRAL CONVECTION BEING DISPLACED SLIGHTLY TO
THE WEST OF THE LOW LEVEL CIRCULATION CENTER. THE INITIAL POSITION
IS BASED ON THE 241811Z GPM MICROWAVE LOW REFLECTIVITY CIRCULATION
FEATURE. THE INITIAL INTENSITY OF 45 KNOTS IS BASED ON AN OVERALL
ASSESSMENT OF OBJECTIVE AND MULTI-AGENCY DVORAK ESTIMATES.
ENVIRONMENTAL CONDITIONS ARE CURRENTLY MARGINAL AS MODERATE
(15-20 KNOT) EASTERLY VERTICAL WIND SHEAR (VWS) HAS PERSISTED,
ALBEIT OVER WARM (29C) SEA SURFACE TEMPERATURES. CURRENTLY, TS
08W IS TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF A
BUILDING DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. THE STR WILL CONTINUE TO STEER TS SONCA WESTWARD FOR THE
REMAINDER OF ITS LIFESPAN. VWS IS EXPECTED TO BE MARGINAL TO
UNFAVORABLE. THIS, COUPLED WITH IMPENDING LAND INTERACTION WITH
VIETNAM, WILL GRADUALLY THEN RAPIDLY ERODE THE SYSTEM.
LANDFALL IS EXPECTED NEAR TAU 18 AND FULL DISSIPATION
BY TAU 36 OVER MOUNTAINOUS TERRAIN. DYNAMIC MODEL
GUIDANCE REMAINS IN GOOD AGREEMENT, LENDING
HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//

[dexterlabio]

This storm is not talked about much but I'm starting to worry for the people in Vietnam. Though it isn't a typhoon it's bringing in more moisture thanks to the southwest monsoon, and Sonca has been quasi-stationary for quite some time.

[doomhaMwx]

Sonca passed a bit more south from Hainan than what was expected yesterday (If it passed closer to Hainan, then it would remain over water for a bit longer), thus, it should make landfall later today, in the afternoon or early evening hours (Vietnam time)...





Heavy rainfall is the main threat to Central Vietnam, Central/Southern Laos, and northern Thailand...

[euro6208]

WDPN32 PGTW 250300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (SONCA) WARNING
NR 17//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 08W (SONCA), LOCATED APPROXIMATELY 45 NM NORTH-
NORTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 11 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
SHOWS PERSISTENT CENTRAL CONVECTION BEING DISPLACED SLIGHTLY TO THE
WEST OF THE LOW LEVEL CIRCULATION CENTER. THE INITIAL POSITION IS
BASED ON A DIMPLE FEATURE IN THE MSI LOOP WITH FAIR CONFIDENCE. THE
INITIAL INTENSITY OF 45 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF
OBJECTIVE AND MULTI-AGENCY DVORAK ESTIMATES. ENVIRONMENTAL CONDITIONS
ARE CURRENTLY MARGINAL AS MODERATE (15-20 KNOT) EASTERLY VERTICAL
WIND SHEAR (VWS) HAS PERSISTED, ALBEIT OVER WARM (29C) SEA SURFACE
TEMPERATURES. CURRENTLY, TS 08W IS TRACKING WESTWARD ALONG THE
SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE
NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. THE STR WILL CONTINUE TO STEER TS SONCA WESTWARD FOR THE
REMAINDER OF ITS LIFESPAN. VWS IS EXPECTED TO BE MARGINAL TO
UNFAVORABLE. THIS, COUPLED WITH IMPENDING LAND INTERACTION WITH
VIETNAM, WILL GRADUALLY THEN RAPIDLY ERODE THE SYSTEM. LANDFALL IS
EXPECTED AFTER TAU 06 AND FULL DISSIPATION BY TAU 24 OVER MOUNTAINOUS
TERRAIN. DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT, LENDING
HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN

[doomhaMwx]

Tropical Storm Sonca came ashore just to the north of Hue city this Tuesday afternoon...
As of 06z(1pm Vietnam time), a station in Hue reported/recorded heavy rainfall with an 18hr accumulation of 115mm...


Satellite image @ 08z / 3pm Vietnam time

[euro6208]

WTPN32 PGTW 250900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL STORM 08W (SONCA) WARNING NR 018
03 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
250600Z --- NEAR 17.0N 107.2E
MOVEMENT PAST SIX HOURS - 275 DEGREES AT 12 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
RADIUS OF 034 KT WINDS - 045 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
REPEAT POSIT: 17.0N 107.2E
---
FORECASTS:
12 HRS, VALID AT:
251800Z --- 17.1N 105.2E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 24 HR POSIT: 265 DEG/ 09 KTS
---
24 HRS, VALID AT:
260600Z --- 17.0N 103.3E
MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
250900Z POSITION NEAR 17.0N 106.7E.
TROPICAL STORM 08W (SONCA), LOCATED APPROXIMATELY 87 NM NORTHWEST
OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 12 KNOTS OVER THE
PAST SIX 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 250600Z IS 12 FEET. REFER TO TYPHOON 07W (NORU) WARNINGS (WTPN31
PGTW)FOR SIX-HOURLY UPDATES. REFER TO TROPICAL STORM 09W (KULAP)
WARNINGS (WTPN33 PGTW)FOR SIX-HOURLY UPDATES.
//
NNNN

[HURAKAN]

Sonca still looks quite impressive over southeast Asia more than a day after landfall in Vietnam

[mrbagyo]

yep

[euro6208]

Impressive.

[1900hurricane]

Sonca is still keeping on!