WPAC: ATSANI - Post-Tropical

[euro6208]

WTPN22 PGTW 131930
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/131721ZAUG2015//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
170 NM EITHER SIDE OF A LINE FROM 13.1N 163.8E TO 18.0N 160.6E
WITHIN THE NEXT 06 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 15 TO 20 KNOTS. METSAT
IMAGERY AT 131900Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 14.0N 163.0E. THE SYSTEM IS MOVING NORTHWESTWARD AT 14
KNOTS.
2. REMARKS:
THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 13.2N 164.2E, IS
NOW LOCATED NEAR 14.0N 163.0E, APPROXIMATELY 365 NM SOUTH-SOUTHWEST
OF WAKE ISLAND. RECENT ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
DEPICTS FORMATIVE BANDS OVER THE NORTHERN AND SOUTHERN SEMI-CIRCLE
WRAPPING INTO A LLCC THAT IS BECOMING MORE DEFINED. UPPER-LEVEL
ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW VWS AND GOOD DUAL
OUTFLOW. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB.
DUE TO IMPROVED ORGANIZATION, THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO
HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
141930Z.
4. SEE REF A FOR DETAILS ON A TROPICAL CYCLONE FORMATION ALERT
LOCATED NEAR 11.8N 151.8E.//
NNNN

[cycloneye]

WTPN32 PGTW 140900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL DEPRESSION 17W (SEVENTEEN) WARNING NR 001
02 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
140600Z --- NEAR 15.1N 163.0E
MOVEMENT PAST SIX HOURS - 350 DEGREES AT 05 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
WIND RADII VALID OVER OPEN WATER ONLY
REPEAT POSIT: 15.1N 163.0E
---
FORECASTS:
12 HRS, VALID AT:
141800Z --- 15.5N 162.9E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 24 HR POSIT: 340 DEG/ 02 KTS
---
24 HRS, VALID AT:
150600Z --- 15.8N 162.8E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
035 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
035 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 315 DEG/ 02 KTS
---
36 HRS, VALID AT:
151800Z --- 16.1N 162.5E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
065 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
070 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 310 DEG/ 02 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
160600Z --- 16.4N 162.1E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
035 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 095 NM NORTHEAST QUADRANT
090 NM SOUTHEAST QUADRANT
085 NM SOUTHWEST QUADRANT
095 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 300 DEG/ 05 KTS
---
72 HRS, VALID AT:
170600Z --- 17.4N 160.4E
MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT
035 NM SOUTHEAST QUADRANT
035 NM SOUTHWEST QUADRANT
035 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT
060 NM SOUTHEAST QUADRANT
060 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 130 NM NORTHEAST QUADRANT
120 NM SOUTHEAST QUADRANT
120 NM SOUTHWEST QUADRANT
130 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 310 DEG/ 08 KTS
---
LONG RANGE OUTLOOK:
---
96 HRS, VALID AT:
180600Z --- 19.5N 157.7E
MAX SUSTAINED WINDS - 120 KT, GUSTS 145 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 120 HR POSIT: 315 DEG/ 09 KTS
---
120 HRS, VALID AT:
190600Z --- 22.1N 155.0E
MAX SUSTAINED WINDS - 125 KT, GUSTS 150 KT
WIND RADII VALID OVER OPEN WATER ONLY
---
REMARKS:
140900Z POSITION NEAR 15.2N 163.0E.
TROPICAL DEPRESSION 17W (SEVENTEEN), LOCATED APPROXIMATELY 326 NM
SOUTHWEST OF WAKE ISLAND, HAS TRACKED NORTHWARD AT 05 KNOTS OVER
THE PAST SIX HOURS.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 140600Z IS 10 FEET. NEXT
WARNINGS AT 141500Z, 142100Z, 150300Z AND 150900Z.
REFER TO TROPICAL DEPRESSION 16W (SIXTEEN) WARNINGS (WTPN31 PGTW)
FOR SIX-HOURLY UPDATES.
//
NNNN

[euro6208]

WDPN31 PGTW 140900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 17W WARNING NR
01//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 17W (SEVENTEEN), LOCATED APPROXIMATELY
326 NM SOUTHWEST OF WAKE ISLAND, HAS TRACKED NORTHWARD AT 05 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS PERSISTENT DEEP CONVECTION WITH FORMATIVE BANDS OVER
THE NORTHERN AND SOUTHERN SEMI-CIRCLE OF A DEVELOPING LOW-LEVEL
CIRCULATION CENTER. A 140336Z SSMI MICROWAVE IMAGE REVEALS BROKEN,
BUT TIGHTLY-CURVED CONVECTIVE BANDING WRAPPING INTO THE CENTER. THE
CURRENT POSITION IS BASED ON THE MSI, AFOREMENTIONED MICROWAVE IMAGE
AND SATELLITE FIXES FROM PGTW AND RJTD WITH GOOD CONFIDENCE. THE
INITIAL INTENSITY OF 25 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF
DVORAK INTENSITY ESTIMATES FROM ALL REPORTING AGENCIES. UPPER-LEVEL
ANALYSIS INDICATES TD 17W IS LOCATED IN AN AREA OF MODERATE (15 TO
20 KNOT) VERTICAL WIND SHEAR (VWS) BEING OFFSET BY THE GOOD RADIAL
OUTFLOW AS EVIDENT ON THE WATER VAPOR IMAGERY. TD 17W IS TRACKING
UNDER THE INFLUENCE OF A WEAK STEERING ENVIRONMENT BETWEEN A
SUBTROPICAL RIDGE (STR) TO THE NORTH AND A NEAR-EQUATORIAL RIDGE
(NER) TO THE SOUTH.
3. FORECAST REASONING.
A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST
PHILOSOPHY.
B. SLOW AND/OR POSSIBLY QUASI-STATIONARY MOVEMENT IS EXPECTED
OVER THE NEXT 48 HOURS AS THE SYSTEM REMAINS IN A WEAK STEERING
ENVIRONMENT. BY TAU 48, THE STR IS FORECAST TO BUILD AND ASSUME THE
STEERING PATTERN DRIVING TD 17W NORTHWESTWARD. CONCURRENTLY,
MARGINALLY FAVORABLE CONDITIONS WILL PERSIST IN THE NEAR TERM,
ALLOWING SLOW INTENSIFICATION. AFTER TAU 48, IN ADDITION TO
FAVORABLE ENVIRONMENTAL CONDITIONS, IMPROVED UPPER-LEVEL OUTFLOW AND
DECREASING VWS WILL ALLOW THE SYSTEM TO UNDERGO RAPID
INTENSIFICATION (RI) THROUGH TAU 72.
C. THE SYSTEM WILL MAINTAIN A NORTHWESTWARD TRAJECTORY. FAVORABLE
CONDITIONS WILL PERSIST LEADING TO FURTHER RI. LIMITED MODEL
GUIDANCE INDICATES A SIGNIFICANT DIFFERENCE IN THE TRACK AND TRACK
SPEEDS IN THE SHORT TERM AND A LARGE SPREAD IN THE EXTENDED TAUS.
FOR THIS REASON, THE JTWC TRACK FORECAST CONFIDENCE LEVEL IS LOW.//
NNNN

[euro6208]

000
WTPQ32 PGUM 140926
TCPPQ2

BULLETIN
TROPICAL DEPRESSION 17W ADVISORY NUMBER 1
NATIONAL WEATHER SERVICE TIYAN GU WP172015
800 PM CHST FRI AUG 14 2015

...TROPICAL DEPRESSION 17W FORMED SOUTHWEST OF WAKE ISLAND...

CHANGES WITH THIS ADVISORY
--------------------------
NONE.

WATCHES AND WARNINGS
--------------------
NONE.

SUMMARY OF 700 PM CHST...0900 UTC...INFORMATION
-----------------------------------------------
LOCATION...15.2N 163.0E

ABOUT 265 MILES NORTH OF ENEWETAK
ABOUT 370 MILES SOUTHWEST OF WAKE ISLAND
ABOUT 1150 MILES EAST OF SAIPAN
ABOUT 1225 MILES EAST OF GUAM
ABOUT 1145 MILES EAST OF ALAMAGAN

MAXIMUM SUSTAINED WINDS...30 MPH
PRESENT MOVEMENT...NORTH...350 DEGREES AT 6 MPH.

DISCUSSION AND OUTLOOK
----------------------
AT 700 PM CHST...0900 UTC...THE CENTER OF TROPICAL DEPRESSION 17W
WAS LOCATED NEAR LATITUDE 15.2 NORTH AND LONGITUDE 163.0 EAST...
DRIFTING NORTH AT 6 MPH. THIS GENERAL MOTION IS EXPECTED THROUGH
SATURDAY...BEFORE TURNING NORTHWEST SUNDAY.

MAXIMUM SUSTAINED WINDS ARE 30 MPH....TROPICAL DEPRESSION 17W IS
FORECASTED TO GRADUALLY INTENSIFY OVER THE NEXT FEW DAYS AND MIGHT
BECOME A TROPICAL STORM ON SATURDAY.

NEXT ADVISORY
-------------
THE NEXT SCHEDULED ADVISORY WILL BE ISSUED BY THE NATIONAL WEATHER
SERVICE AT 200 AM LATE TONIGHT.

$$

CHAN

[euro6208]

[euro6208]

Super intense intensification...925 mb in just 120 hours...



908 mb in 218 hours...Keeps it at 910 mb or lower for over 3 days...

[euro6208]

06Z GFS with a peak of 881 mb, past runs had this much stronger typhoon somewhere in the 870's range...Good thing it's recurving...

[cycloneye]

WDPN32 PGTW 141500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 17W (SEVENTEEN)
WARNING NR 02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 17W (SEVENTEEN), LOCATED APPROXIMATELY
352 NM SOUTHWEST OF WAKE ISLAND, HAS TRACKED WESTWARD AT 05 KNOTS
OVER THE PAST SIX HOURS. RECENT ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY AND A 141036Z SSMI MICROWAVE IMAGE DEPICTS BROKEN,
YET TIGHTLY-CURVED CONVECTIVE BANDING WRAPPING INTO THE LOW-LEVEL
CIRCULATION CENTER. THE CURRENT POSITION IS BASED ON THE EIR LOOP,
AFOREMENTIONED MICROWAVE IMAGE AND SATELLITE FIXES FROM PGTW AND
RJTD WITH GOOD CONFIDENCE. THE INITIAL INTENSITY OF 30 KNOTS IS
BASED ON CORRESPONDING DVORAK INTENSITY ESTIMATES OF T2.0 (30 KNOTS)
FROM ALL REPORTING AGENCIES. UPPER-LEVEL ANALYSIS INDICATES TD 17W
IS LOCATED IN AN AREA OF MODERATE (15 TO 20 KNOT) VERTICAL WIND
SHEAR (VWS) BEING OFFSET BY GOOD RADIAL OUTFLOW AS EVIDENT ON THE
WATER VAPOR IMAGERY. ADDITIONALLY, THE TUTT CELL LOCATED TO THE
NORTH OF THE SYSTEM CONTINUES DISRUPTING CONVECTIVE ORGANIZATION.
HOWEVER, WARM SEA SURFACE TEMPERATURES IN THE AREA ARE CONDUCIVE FOR
FURTHER DEVELOPMENT. TD 17W IS TRACKING UNDER THE INFLUENCE OF A
COMPETING STEERING ENVIRONMENT BETWEEN A SUBTROPICAL RIDGE (STR) TO
THE NORTH AND A NEAR-EQUATORIAL RIDGE (NER) TO THE SOUTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. SLOW MOVEMENT IS EXPECTED OVER THE NEXT 48 HOURS AS THE SYSTEM
REMAINS IN A COMPETING STEERING ENVIRONMENT. BY TAU 48, THE STR IS
FORECAST TO BUILD AND ASSUME THE STEERING PATTERN DRIVING TD 17W
NORTHWESTWARD. CONCURRENTLY, MARGINALLY FAVORABLE CONDITIONS WILL
PERSIST IN THE NEAR TERM, ALLOWING SLOW INTENSIFICATION. AFTER TAU
48, IN ADDITION TO FAVORABLE ENVIRONMENTAL CONDITIONS, IMPROVED
UPPER-LEVEL OUTFLOW AND DECREASING VWS WILL ALLOW THE SYSTEM TO
UNDERGO RAPID INTENSIFICATION (RI) THROUGH TAU 72.
C. TD 17W WILL MAINTAIN A NORTHWESTWARD TRAJECTORY THROUGH THE
REMAINDER OF THE FORECAST PERIOD. FAVORABLE CONDITIONS WILL PERSIST
LEADING TO FURTHER RI THROUGH TAU 96. AFTERWARDS, THE COMBINED
EFFECT OF INCREASING VWS AND LOWER OCEAN HEAT CONTENT WILL BEGIN TO
WEAKEN THE SYSTEM. AVAILABLE MODEL GUIDANCE HAS SLIGHTLY IMPROVED
FOR THE EXTENDED TAUS OVER THE PAST SIX HOURS, BUT CONTINUES TO SHOW
SIGNIFICANT TRACK SPEEDS DIFFERENCES IN THE SHORT TERM. DUE TO
POSITIONING UNCERTAINTY IN THE SHORT TERM, THE JTWC TRACK FORECAST
CONFIDENCE LEVEL REMAINS LOW.//
NNNN

[1900hurricane]

The above is for 16W, not 17W.

[cycloneye]

:uarrow: The above is for 16W, not 17W.

Fixed it.Thanks for letting me know.

[cycloneye]

JMA upgrades to TS ATSANI.

TS 1516 (ATSANI)
Issued at 19:00 UTC, 14 August 2015


<Analyses at 14/18 UTC>
Scale -
Intensity -
Center position N15°10'(15.2°)
E161°25'(161.4°)
Direction and speed of movement W 15km/h(8kt)
Central pressure 1000hPa
Maximum wind speed near the center 18m/s(35kt)
Maximum wind gust speed 25m/s(50kt)
Area of 30kt winds or more ALL150km(80NM)

<Forecast for 15/18 UTC>
Intensity -
Center position of probability circle N15°30'(15.5°)
E160°50'(160.8°)
Direction and speed of movement Almost stationary
Central pressure 996hPa
Maximum wind speed near the center 20m/s(40kt)
Maximum wind gust speed 30m/s(60kt)
Radius of probability circle 130km(70NM)

<Forecast for 16/18 UTC>
Intensity -
Center position of probability circle N15°55'(15.9°)
E160°10'(160.2°)
Direction and speed of movement Almost stationary
Central pressure 985hPa
Maximum wind speed near the center 25m/s(50kt)
Maximum wind gust speed 35m/s(70kt)
Radius of probability circle 200km(110NM)

<Forecast for 17/18 UTC>
Intensity Strong
Center position of probability circle N16°30'(16.5°)
E159°30'(159.5°)
Direction and speed of movement Almost stationary
Central pressure 965hPa
Maximum wind speed near the center 35m/s(70kt)
Maximum wind gust speed 50m/s(100kt)
Radius of probability circle 300km(160NM)
Storm warning area ALL430km(230NM)

[1900hurricane]

Looks like both were upgraded at the same time. I'm guessing JMA gives the one that has been classified by them as a depression the longest the first name on the list.

[euro6208]

EURO peaks this at 896 mb...

Twin Cat 5's...

[euro6208]

Only 945 mb peak from GFS...

[euro6208]

16th TS of the season!

17W ATSANI 150814 1800 15.1N 161.9E WPAC 35 996

[euro6208]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 14 AUG 2015 Time : 200000 UTC
Lat : 15:08:37 N Lon : 161:59:25 E


CI# /Pressure/ Vmax
2.6 /1003.3mb/ 37.0kt


Final T# Adj T# Raw T#
2.6 2.1 2.1

Center Temp : -40.9C Cloud Region Temp : -52.2C

Scene Type : CURVED BAND with 0.38 ARC in LT GRAY
Maximum CURVED BAND with 0.68 ARC in LT GRAY
at Lat: 15:56:23 N Lon: 160:59:24 E

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : WEST PACIFIC
Dvorak CI > MSLP Conversion Used : CKZ Method

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : N/A
- Environmental MSLP : 1009mb

Satellite Name : MTSAT2
Satellite Viewing Angle : 26.4 degrees

[Siker]

Only 945 mb peak from GFS...

Worth noting that is not the full resolution slp forecast. Here is the actual modeled peak:

[Yellow Evan]

Looks around 40 knts. While the banding the storm has is definitely nice, Atsani doesn't have much convection and isn't too organized. Still, the waters are warm and the shear is low, so I expect significant intensification, even though there are no signs of an inner core yet.

[cycloneye]

17W ATSANI 150815 0000 14.9N 162.1E WPAC 35 996

[dexterlabio]

The latest ECMWF run shows a strengthening midlatitude trough so perhaps that will introduce a weakness to the north thus pulling Atsani and Goni away to the NE...of course still a very close call for Japan...