WPAC: 26W - Tropical Depression

[euro6208]

Southwest of Iwo Jima...

[supercane]

JMA now has this as a non-warning TD, joining 93W:
TROPICAL DEPRESSION 1008 HPA AT 17N 164E WNW SLOWLY.

[supercane]

ABPW10 PGTW 200600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
/SOUTH PACIFIC OCEANS/200600Z-210600ZOCT2015//
<snip>
(2) AN AREA OF CONVECTION HAS PERSISTED NEAR 17.6N 163.1E,
APPROXIMATELY 220 NM WEST-SOUTHWEST OF WAKE ISLAND. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY DEPICTS A FULLY EXPOSED LLCC WITH
ISOLATED DEEP CONVECTION FLARING OVER THE SOUTHWEST QUADRANT. A
192256Z METOP-B 89GHZ IMAGE INDICATES BROAD, SHALLOW BANDING
WRAPPING INTO AN ELONGATED LLCC WITH WEAK BANDING OVER THE SOUTHWEST
QUADRANT. A 191931Z WINDSAT IMAGE INDICATES A DEFINED CIRCULATION
WITH 15-20 KNOT WINDS OVER THE NORTHERN SEMI-CIRCLE AND WEAKER WINDS
ELSEWHERE. THE UPPER LEVEL ENVIRONMENT REMAINS MARGINAL WITH
MODERATE VERTICAL WIND SHEAR AND BROAD DIFFLUENCE. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 12 TO 18 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS LOW.
<rest omitted>

[euro6208]

JTWC quite busy...

[euro6208]

TXPQ28 KNES 200413
TCSWNP

A. TROPICAL DISTURBANCE (94W)

B. 20/0232Z

C. 17.6N

D. 162.8E

E. THREE/MTSAT

F. T1.0/1.0/D1.0/24HRS

G. IR/EIR/VIS

H. REMARKS...94W CONTINUES TO UNDERGO NORTHERLY SHEAR WITH A FULLY
EXPOSED LLCC. CENTER HAS CIRCULARLY DEFINED CLOUD LINES AND IS LESS THAN
75 NM FROM A SMALL AREA OF CONVECTIVE OVERCAST FOR A DT=1.5. MET=1.0
AND PT=1.0. FT IS BASED ON MET.

I. ADDL POSITIONS

NIL


...RUMINSKI

[supercane]

ABPW10 PGTW 201630
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
/SOUTH PACIFIC OCEANS REISSUED/201630Z-210600ZOCT2015//
<snip>
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 18.0N
162.6E, IS NOW LOCATED NEAR 18.8N 161.8E, APPROXIMATELY 280 NM WEST
OF WAKE ISLAND. ANIMATED ENHANCED IR SHOWS GOOD FLARING CONVECTION
ON THE SOUTHWESTERN SIDE OF A FULLY EXPOSED LLCC. A 201051Z ASCAT
IMAGE SHOWS A CLEAR LLCC WITH SOLID 15 KNOTS AROUND THE CIRCULATION
WITH SOME 20 KNOT WINDS IN THE DEEPEST CONVECTION TO THE SOUTHWEST.
UPPER LEVEL ANALYSIS INDICATED GOOD DIVERGENCE WITH EQUATORWARD
OUTFLOW AND LOW VWS. WHILE GLOBAL MODELS STILL STRUGGLE TO DEVELOP
THE SYSTEM, IT HAS BECOME SOMEWHAT BETTER ORGANIZED OVER THE PAST 12
HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB.
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.

JMA at 12Z:
TROPICAL DEPRESSION 1008 HPA AT 19N 162E NNW 10 KT.

[euro6208]

TXPQ28 KNES 201506
TCSWNP

A. TROPICAL DISTURBANCE (94W)

B. 20/1432Z

C. 19.2N

D. 161.8E

E. FIVE/MTSAT

F. T1.5/1.5/D1.0/24HRS

G. IR/EIR/SWIR

H. REMARKS...SYSTEM IS CHARACTERIZED BY CIRCULARLY DEFINED CLOUD LINES
AND A LLCC THAT IS LESS THAN 1.25 DEGREES FROM A COLD OVERCAST WIDER
THAN 1.5 DEGREES. THIS YIELDS A DT OF 2.0. MET AND PT ARE 1.5. FT IS
BASED ON MET.

I. ADDL POSITIONS

NIL


...VELASCO

[1900hurricane]

Tropical Cyclone Formation Alert now up.

[supercane]

WTPN21 PGTW 202230
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 18.4N 162.2E TO 27.0N 156.4E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 18 TO 23 KNOTS. METSAT
IMAGERY AT 201800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 19.0N 161.4E. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 04
KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 18.0N
162.6E IS NOW LOCATED NEAR 19.3N 162.6E, APPROXIMATELY 300 NM WEST
OF WAKE ISLAND. RECENT ANIMATED INFRARED SATELLITE IMAGERY INDICATES
THE LOW LEVEL CIRCULATION CENTER (LLCC) IS LOCATED NORTHEAST OF THE
BULK OF CONVECTION. UPPER LEVEL ANALYSIS REVEALS THAT THE SYSTEM IS
IN AN AREA OF LOW TO MODERATE VERTICAL WIND SHEAR WITH GOOD
EQUATORWARD OUTFLOW. WHILE THERE IS LIMITED GLOBAL MODEL DEVELOPMENT
OF THIS SYSTEM, THE INCREASE IN PERSISTENT CONVECTION OVER THE PAST
36 HOURS LEADS TO MODERATE CONFIDENCE THAT THIS SYSTEM WILL DEVELOP.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. DUE TO
INCREASED CONSOLIDATION OF THE LLCC, THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
212230Z.//
NNNN

JMA 00Z:
TROPICAL DEPRESSION 1008 HPA AT 20N 159E WNW 10 KT.

Dvorak classifications from SAB last 24hr:
DATE/TIME LAT LON CLASSIFICATION STORM
21/0232 UTC 20.0N 158.9E T1.0/2.0 94W
20/2101 UTC 19.7N 160.1E T2.0/2.0 94W
20/1432 UTC 19.2N 161.8E T1.5/1.5 94W
20/0832 UTC 18.4N 162.4E T1.5/1.5 94W
20/0232 UTC 17.6N 162.8E T1.0/1.0 94W

JTWC at T1.0/1.0

[supercane]

WTPQ20 RJTD 211200
RSMC TROPICAL CYCLONE ADVISORY
NAME TD
ANALYSIS
PSTN 211200UTC 21.6N 157.7E FAIR
MOVE NW SLOWLY
PRES 1006HPA
MXWD 030KT
GUST 045KT
FORECAST
24HF 221200UTC 27.5N 158.8E 120NM 70%
MOVE NNE 22KT
PRES 998HPA
MXWD 035KT
GUST 050KT =

[1900hurricane]

Probably time to classify.

[euro6208]

TPPN13 PGTW 211826

A. TROPICAL DISTURBANCE 94W (W OF WAKE ISLAND)

B. 21/1730Z

C. 22.83N

D. 156.39E

E. SIX/HMWRI8

F. T1.5/1.5/D0.5/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 47A/PBO PTLY XPSD LLCC/ANMTN. CNVCTN WRAP OF .30 ON
LOG10 SPIRAL YIELDS A DT OF 1.5. PT AGREES. MET YIELDS A 1.0.
DBO DT.

I. ADDITIONAL POSITIONS: NONE


UEHARA

[euro6208]

THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 19.3N
160.6E IS NOW LOCATED NEAR 20.5N 158.4E, APPROXIMATELY 470 NM WEST
OF WAKE ISLAND. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A
BROAD, EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH DEEP
CONVECTION SHEARED OVER THE SOUTHWEST QUADRANT OF THE LLCC. A
210403Z SSMI IMAGE REVEALS SHALLOW BANDING WRAPPING INTO A BROAD
LLCC WITH ISOLATED DEEP CONVECTION. A 202232Z ASCAT IMAGE SHOWED 15
TO 20 KNOT WINDS ASSOCIATED WITH AN ELONGATED CIRCULATION. UPPER-
LEVEL ANALYSIS SHOWS A MARGINAL ENVIRONMENT WITH MODERATE (15 TO 20
KNOTS) NORTHERLY VERTICAL WIND SHEAR OFFSET BY EQUATORWARD OUTFLOW.
THE DYNAMIC MODELS CONTINUE TO INDICATE WEAK DEVELOPMENT AS THE
SYSTEM TRACKS POLEWARD. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1006 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS
HIGH.

[supercane]

WTPQ20 RJTD 211800
RSMC TROPICAL CYCLONE ADVISORY
NAME TD
ANALYSIS
PSTN 211800UTC 22.6N 156.5E FAIR
MOVE NW 08KT
PRES 1004HPA
MXWD 030KT
GUST 045KT
FORECAST
24HF 221800UTC 29.0N 158.5E 120NM 70%
MOVE NNE 22KT
PRES 996HPA
MXWD 035KT
GUST 050KT =

[1900hurricane]

Now listed as 26W on the NRL page.

[cycloneye]

TD
Issued at 01:00 UTC, 22 October 2015


<Analyses at 22/00 UTC>
Scale -
Intensity -
TD
Center position N23°10'(23.2°)
E155°10'(155.2°)
Direction and speed of movement WNW 25km/h(13kt)
Central pressure 1004hPa
Maximum wind speed near the center 15m/s(30kt)
Maximum wind gust speed 23m/s(45kt)

<Forecast for 22/12 UTC>
Intensity -
TD
Center position of probability circle N26°25'(26.4°)
E156°10'(156.2°)
Direction and speed of movement NNE 30km/h(17kt)
Central pressure 1000hPa
Maximum wind speed near the center 15m/s(30kt)
Maximum wind gust speed 23m/s(45kt)
Radius of probability circle 90km(50NM)

<Forecast for 23/00 UTC>
Intensity -
Center position of probability circle N29°40'(29.7°)
E160°35'(160.6°)
Direction and speed of movement NE 45km/h(25kt)
Central pressure 996hPa
Maximum wind speed near the center 18m/s(35kt)
Maximum wind gust speed 25m/s(50kt)
Radius of probability circle 220km(120NM)

[1900hurricane]

There's a swirl escaping to the north, but it looks like a cast-away vort based on the latest GPM pass. Looks like JTWC initialized in the correct location, back near the NE edge of the convection.

[supercane]

WTPQ20 RJTD 220000
RSMC TROPICAL CYCLONE ADVISORY
NAME TD
ANALYSIS
PSTN 220000UTC 23.2N 155.2E FAIR
MOVE WNW 13KT
PRES 1004HPA
MXWD 030KT
GUST 045KT
FORECAST
24HF 230000UTC 29.7N 160.6E 120NM 70%
MOVE NE 25KT
PRES 996HPA
MXWD 035KT
GUST 050KT =

WTPQ30 RJTD 220000

RSMC TROPICAL CYCLONE PROGNOSTIC REASONING
REASONING NO. 1 FOR TD LOCATED AT 23.2N 155.2E
1.GENERAL COMMENTS
POSITION FORECAST IS MAINLY BASED ON NWP AND PERSISTENCY.
2.SYNOPTIC SITUATION
NOTHING PARTICULAR TO EXPLAIN.
3.MOTION FORECAST
POSITION ACCURACY AT 220000 UTC IS FAIR.
TD WILL ACCELERATE FOR THE NEXT 24 HOURS.
TD WILL RECURVE WITHIN 12 HOURS FROM 220000 UTC.
TD WILL MOVE NORTH-NORTHEAST FOR THE NEXT 12 HOURS THEN MOVE GRADUALLY TO NORTHEAST.
4.INTENSITY FORECAST
TD WILL BE GRADED UP TO TS WITHIN 24 HOURS.
TD WILL DEVELOP BECAUSE CYCLONE WILL STAY IN HIGH SST AREA.
FI-NUMBER WILL BE 2.5 AFTER 24 HOURS.
TD WILL BE TRANSFORMED TO EXTRATROPICAL CYCLONE WITHIN 48 HOURS.=

First JTWC advisory:
WTPN51 PGTW 220300
WARNING ATCG MIL 26W NWP 151022004231
2015102200 26W TWENTYSIX 001 03 310 13 SATL 020
T000 235N 1553E 025
T012 266N 1559E 030
T024 304N 1610E 030
T036 331N 1680E 030
T048 345N 1764E 030
AMP
024HR BECOMING EXTRATROPICAL
036HR BECOMING EXTRATROPICAL
048HR EXTRATROPICAL
SUBJ: TROPICAL DEPRESSION 26W (TWENTYSIX) WARNING NR 001
<rest omitted>

[1900hurricane]

Both RSCAT (attached below) and ASCAT actually show a circulation open to the west, with the open trough axis extending back towards what is left of 93W. With this now at light, 26W technically shouldn't be classified as a tropical depression. It had me fooled, and apparently the agencies too.



It should also be noted that the scatterometer passes showed the circulation was closed 12-15 hours ago.

[euro6208]

WDPN31 PGTW 220900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 26W (TWENTYSIX)
WARNING NR 02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 26W (TWENTYSIX), LOCATED APPROXIMATELY
747 NM WEST-NORTHWEST OF WAKE ISLAND, HAS TRACKED NORTH-
NORTHWESTWARD AT 19 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY EXPOSED
LOW LEVEL CIRCULATION CENTER (LLCC) WITH FLARING CONVECTION TO THE
SOUTHEAST OF CENTER. A 220349Z SSMI 85GHZ MICROWAVE IMAGE SHOWS
DEFINED SHALLOW BANDING WRAPPING INTO THE LLCC WITH LIMITED AND
DISORGANIZED DEEP CONVECTION. THE INITIAL POSITION IS BASED ON THE
LLCC IN THE ABOVE IMAGERY WITH LIMITED CONFIDENCE. THE CURRENT
INTENSITY HAS BEEN HELD AT 25 KNOTS USING THE CURRENT INTENSITY
ESTIMATES FROM PGTW AND RJTD. TD 25W IS LOCATED IN A MARGINAL
ENVIRONMENT WITH 10 TO 20 KNOT VERTICAL WIND SHEAR BEING PARTIALLY
OFFSET BY DUAL CHANNEL OUTFLOW. HOWEVER, WATER VAPOR IMAGERY SHOWS
SUBSIDENCE ALONG THE NORTHWESTERN QUADRANT OF THE LLCC, PREVENTING
CONVECTIVE DEVELOPMENT OVER THE LLCC. THE CYCLONE IS TRACKING ALONG
THE SOUTHERN PERIPHERY OF A LOW- TO MID-LAYERED SUB-TROPICAL RIDGE
(STR) TO THE EAST-NORTHEAST.
3. FORECAST REASONING.
A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TD 26W IS EXPECTED TO TRACK NORTHEASTWARD AS IT ROUNDS THE STR
AXIS. OVER THE NEXT 12 HOURS, THE SYSTEM WILL BEGIN TO EMBED IN THE
MID-LATITUDE WESTERLY FLOW; BEGINNING EXTRA-TROPICAL TRANSITION
(ETT). INCREASED POLEWARD OUTFLOW WILL ALLOW THE SYSTEM TO SLIGHTLY
INTENSIFY AS IT TRACKS POLEWARD. TD 26W WILL COMPLETE ETT BY THE END
OF THE FORECAST PERIOD OR POSSIBLE SOONER, BECOMING A WEAK COLD CORE
LOW. IT IS ALSO POSSIBLE THAT THE SYSTEM DISSIPATES PRIOR TO ETT DUE
TO HIGH VWS. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGHOUT
THE FORECAST PERIOD; HOWEVER, GIVEN THE BROAD AND WEAK LOW LEVEL
STRUCTURE AND THE UNCERTAINTY IN THE FORECAST INTENSITY, THERE IS AN
OVERALL LOW CONFIDENCE IN THE JTWC FORECAST.//
NNNN