WPAC: SONGDA - Tropical Depression (1102/04W)

[HURAKAN]

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[RobWESTPACWX]

1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
A. TROPICAL STORM (TS) 04W (FOUR), LOCATED APPROXIMATELY 180 NM
EAST-SOUTHEAST OF YAP, HAS TRACKED WEST-NORTHWESTWARD AT 06 KNOTS
OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS
THE SYSTEM HAS QUICKLY CONSOLIDATED AS FORMATIVE BANDS WRAPPED
TIGHTER INTO THE LOW LEVEL CIRCULATION CENTER. THE INITIAL POSITION
IS BASED ON THE ABOVE ANIMATION AND EXTRAPOLATED FROM A 200758Z
WINDSAT SCATTEROMETRY PASS WITH POOR CONFIDENCE. THE INITIAL
INTENSITY IS BASED ON A DVORAK ESTIMATE OF 35 KNOTS FROM PGTW. UPPER
LEVEL ANALYSIS INDICATES THE SYSTEM IS JUST TO THE SOUTH OF A RIDGE
AXIS IN AN AREA OF LOW TO MODERATE VERTICAL WIND SHEAR (VWS) AND
GOOD POLEWARD OUTFLOW. THIS IS ALSO EVIDENT ON ANIMATED WATER VAPOR
IMAGERY. TS 04W IS CURRENTLY TRACKING ALONG THE SOUTHWEST PERIPHERY
OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR) EAST OF JAPAN.
3. FORECAST REASONING
A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST
PHILOSOPHY.
B. TS 04W IS EXPECTED TO CONTINUE ALONG THIS TRACK FOR THE ENTIRE
FORECAST PERIOD. AS THE SYSTEM MOVES FURTHER POLEWARD, ENHANCED
OUTFLOW AND LOWER VWS UNDER THE RIDGE AXIS WILL FAVOR GRADUAL
INTENSIFICATION, FUELED BY WARM SEA SURFACE TEMPERATURES IN THE
PHILIPPINE SEA. AFTER TAU 48, THE STEERING STR WILL MOVE FURTHER
NORTHEAST CAUSING THE SYSTEM TO TRACK ON A MORE NORTHWESTWARD
TRAJECTORY.
C. TS 04W WILL REACH TYPHOON INTENSITY BY TAU 72. A SECONDARY STR
ANCHORED OVER SOUTHERN JAPAN WILL ASSUME STEERING AND CAUSE THE
SYSTEM TO TRACK MORE WESTWARD. GIVEN THE FAVORABLE CONDITIONS, 04W
WILL CONTINUE TO INTENSIFY, REACHING 90 KNOTS BY END OF FORECAST
PERIOD. THE LIMITED NUMERICAL GUIDANCE IS IN FAIR AGREEMENT WITH
THIS TRACK FORECAST.//
NNNN

[StormingB81]

JMA is about to upgrade they have started to issue warnings:

TD
Issued at 21:45 UTC, 20 May 2011
<Analyses at 20/21 UTC>
Scale -
Intensity -
TD
Center position N8°35'(8.6°)
E139°10'(139.2°)
Direction and speed of movement W Slowly
Central pressure 1002hPa
Maximum wind speed near the center 15m/s(30kt)
Maximum wind gust speed 23m/s(45kt)

<Forecast for 21/21 UTC>
Intensity -
Center position of probability circle N10°10'(10.2°)
E137°25'(137.4°)
Direction and speed of movement NW 10km/h(6kt)
Central pressure 998hPa
Maximum wind speed near the center 18m/s(35kt)
Maximum wind gust speed 25m/s(50kt)
Radius of probability circle 220km(120NM)

[wxman57]

Center remains exposed NW of the convection.

[cycloneye]

Center remains exposed NW of the convection.

Yes,is clearly seen.

[ManilaTC]

4 Models are on a dead split (2-2) on their 20/12 runs
CMC and UKMET - Track 04W WNWward into Catanduanes and Central Luzon
GFS and NGP - Slightly Poleward bias toward Northern Luzon

ECMWF has no 20/12 run.

[oaba09]

Wow, the models are having a hard time forecasting the path of this system...
Should be interesting in the next couple of days...

[phwxenthusiast]

it's probably just the initialization... the storm developed faster than what most models predicted so i'm thinking it's throwing them off a bit, but that's just my opinion

[dexterlabio]

It seems to be a tropical depression struggling from wind shear. Well I do expect that to happen because the shear condition around the area isn't too friendly for some quick consolidation. Though it appears that the shear tendency on the area is starting to decrease, so we could see improvement in the coming hours.

In terms of the track, I have to mention Rob here because I watched one of his videos before and he showed a steering layer chart...that it would be helpful at least to determine the storm's projected movement than following every model runs. I agree on that. I wish I know where to find one.

[Chacor]

WTPQ20 RJTD 210000
RSMC TROPICAL CYCLONE ADVISORY
NAME TD
ANALYSIS
PSTN 210000UTC 08.7N 138.6E FAIR
MOVE W SLOWLY
PRES 1004HPA
MXWD 030KT
GUST 045KT
FORECAST
24HF 220000UTC 09.9N 136.8E 120NM 70%
MOVE WNW SLOWLY
PRES 998HPA
MXWD 035KT
GUST 050KT =

[cycloneye]

Some convection trying to wrap around the center,but shear is still a bit strong.

[phwxenthusiast]

It seems to be a tropical depression struggling from wind shear. Well I do expect that to happen because the shear condition around the area isn't too friendly for some quick consolidation. Though it appears that the shear tendency on the area is starting to decrease, so we could see improvement in the coming hours.

In terms of the track, I have to mention Rob here because I watched one of his videos before and he showed a steering layer chart...that it would be helpful at least to determine the storm's projected movement than following every model runs. I agree on that. I wish I know where to find one.

here: http://tropic.ssec.wisc.edu/real-time/d ... zoom=&time

use different layers depending on the strength of the storm

[oaba09]

It seems to be a tropical depression struggling from wind shear. Well I do expect that to happen because the shear condition around the area isn't too friendly for some quick consolidation. Though it appears that the shear tendency on the area is starting to decrease, so we could see improvement in the coming hours.

In terms of the track, I have to mention Rob here because I watched one of his videos before and he showed a steering layer chart...that it would be helpful at least to determine the storm's projected movement than following every model runs. I agree on that. I wish I know where to find one.

Yup, moderate wind shear is definitely affecting the system right now...JTWC is expecting more favorable conditions for the system to further develop in the coming days(they are expecting for the windspeed to reach 75 knots in 72 hours)...

[Macrocane]

If the Euro it's right it will be fighting the shear for another day or two, after that it may explode into a ver intense typhoon, nothing is sure yet, but that's seems very possible.

[cycloneye]

JTWC goes down to TD 04W

WTPN31 PGTW 210300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL DEPRESSION 04W (FOUR) WARNING NR 004
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 8.9N 138.5E
MOVEMENT PAST SIX HOURS - 270 DEGREES AT 05 KTS
POSITION ACCURATE TO WITHIN 040 NM
POSITION BASED ON CENTER LOCATED BY A COMBINATION OF
SATELLITE AND SYNOPTIC DATA
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
REPEAT POSIT: 8.9N 138.5E
---
FORECASTS:
12 HRS, VALID AT:
211200Z --- 9.1N 137.0E
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 24 HR POSIT: 285 DEG/ 08 KTS
---
24 HRS, VALID AT:
220000Z --- 9.5N 135.5E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 290 DEG/ 05 KTS
---
36 HRS, VALID AT:
221200Z --- 9.9N 134.5E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
055 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 290 DEG/ 07 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
230000Z --- 10.4N 133.1E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
055 NM SOUTHEAST QUADRANT
055 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 295 DEG/ 07 KTS
---
72 HRS, VALID AT:
240000Z --- 11.5N 130.7E
MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT
020 NM SOUTHEAST QUADRANT
020 NM SOUTHWEST QUADRANT
020 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 305 DEG/ 07 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 --- 13.0N 128.3E
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 120 HR POSIT: 310 DEG/ 08 KTS
---
120 HRS, VALID AT:
260000Z --- 15.0N 125.8E
MAX SUSTAINED WINDS - 105 KT, GUSTS 130 KT
WIND RADII VALID OVER OPEN WATER ONLY
---
REMARKS:
210300Z POSITION NEAR 9.0N 138.1E.
TROPICAL DEPRESSION (TD) 04W (FOUR), LOCATED APPROXIMATELY
45 NM SOUTHEAST OF YAP, HAS TRACKED WESTWARD AT 05 KNOTS OVER
THE PAST SIX HOURS. THE SYSTEM WAS DOWNGRADED TO A TD BASED ON
DVORAK ESTIMATES OF 25 TO 30 KNOTS AND OBSERVATIONAL DATA.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 210000Z IS 12 FEET.
NEXT WARNINGS AT 210900Z, 211500Z, 212100Z AND 220300Z.//
NNNN

[oaba09]

[euro6208]

Some models forecast this to rapidly intensify to Super Typhoon strength and possibly category 5! One model has this peaking at 160 knots!

[Chacor]

Please see ftp://texmex.mit.edu/pub/emanuel/Powerpoint/CHIPS.pdf — CHIPS ensembles are not models. They "are constructed by varying the initial intensity, initial rate of intensification, and shear".

[StormingB81]

WTPN31 PGTW 210900
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL DEPRESSION 04W (FOUR) WARNING NR 005
01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
210600Z --- NEAR 8.9N 138.2E
MOVEMENT PAST SIX HOURS - 285 DEGREES AT 04 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
REPEAT POSIT: 8.9N 138.2E
---
FORECASTS:
12 HRS, VALID AT:
211800Z --- 9.3N 137.2E
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 24 HR POSIT: 290 DEG/ 07 KTS
---
24 HRS, VALID AT:
220600Z --- 9.8N 135.9E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 290 DEG/ 07 KTS
---
36 HRS, VALID AT:
221800Z --- 10.3N 134.5E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
050 NM SOUTHWEST QUADRANT
055 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 290 DEG/ 07 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
230600Z --- 10.8N 133.2E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 060 NM NORTHEAST QUADRANT
055 NM SOUTHEAST QUADRANT
055 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 295 DEG/ 05 KTS
---
72 HRS, VALID AT:
240600Z --- 11.7N 131.2E
MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT
020 NM SOUTHEAST QUADRANT
020 NM SOUTHWEST QUADRANT
020 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
045 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 305 DEG/ 06 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:
250600Z --- 12.9N 129.3E
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 120 HR POSIT: 315 DEG/ 07 KTS
---
120 HRS, VALID AT:
260600Z --- 15.0N 127.1E
MAX SUSTAINED WINDS - 105 KT, GUSTS 130 KT
WIND RADII VALID OVER OPEN WATER ONLY
---
REMARKS:
210900Z POSITION NEAR 9.0N 137.9E.
TROPICAL DEPRESSION (TD) 04W (FOUR), LOCATED APPROXIMATELY 35 NM
SOUTH OF YAP, HAS TRACKED WEST-NORTHWESTWARD AT 04 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A
210403Z AMSRE MICROWAVE PASS DEPICT TIGHTLY CURVED LOW LEVEL BANDING
WITH A SMALL BURST OF DEEP CONVECTION BUILDING OVER THE CENTER. A
MAJORITY OF THE DEEPEST CONVECTION CONTINUES TO BE DISPLACED TO THE
SOUTH DUE TO LIGHT TO MODERATE NORTHERLY VERTICAL WIND SHEAR (VWS).
THE CURRENT POSITION IS EXTRAPOLATED FROM ANIMATED MSI AND THE
AFOREMENTIONED MICROWAVE IMAGE WITH FAIR CONFIDENCE. THE CURRENT
INTENSITY IS BASED ON DVORAK ESTIMATES FROM KNES AND PGTW RANGING
FROM 25 TO 30 KNOTS AND SURFACE OBSERVATIONS FROM YAP (JUST 35 NM
NORTH OF THE SYSTEM) INDICATING 10 KT SUSTAINED EASTERLY WINDS AND A
1001 MSLP (EQUIVALENT TO 28 KNOT WINDS ON THE KNAFF-ZEHR SCALE).
UPPER LEVEL ANALYSIS INDICATES THAT THE SYSTEM IS TRACKING TOWARD A
MORE FAVORABLE ENVIRONMENT WITH DECREASING VWS. ANIMATED WATER
VAPOR IMAGERY SHOWS GOOD EQUATORWARD OUTFLOW, WHILE POLEWARD
OUTFLOW CONTINUES TO BE HINDERED BY NORTHERLY VWS. TD 04W IS
CURRENTLY TRACKING UNDER THE INFLUENCE OF A LOW- TO MID-LEVEL
SUBTROPICAL STEERING RIDGE (STR) JUST TO THE NORTH OF THE SYSTEM AND
IS EXPECTED TO TRACK GENERALLY WEST-NORTHWESTWARD AND STEADILY
INTENSIFY THROUGH TAU 72. AFTER TAU 72, THE SYSTEM IS EXPECTED TO
SLOWLY BEGIN TO TURN POLEWARD AS AN APPROACHING MID-LATITUDE
SHORTWAVE TROUGH WEAKENS THE CURRENTLY EAST-WEST ORIENTATED STR.
IMPROVED OUTFLOW AHEAD OF THE UPPER LEVEL TROUGH AS WELL AS
FAVORABLE SEA SURFACE TEMPERATURES ALONG THE FORECAST TRACK WILL
ALLOW THE SYSTEM TO INTENSIFY AT A FASTER RATE IN THE LATER TAUS.
NUMERICAL MODEL GUIDANCE REMAINS IN FAIR AGREEMENT, WITH JGSM AND
GFS STILL ON THE NORTHERN EDGE OF THE AIDS PACKAGE, AND INDICATING A
MORE POLEWARD TRACK. THIS FORECAST FAVORS NOGAPS, GFDN, EGRR, AND
ECMWF, IS POSITIONED CLOSE TO MODEL CONSENSUS, AND IS CONSISTENT
WITH THE PREVIOUS FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
210600Z IS 12 FEET. NEXT WARNINGS AT 211500Z, 212100Z, 220300Z AND
220900Z.//
NNNN

[HURAKAN]

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