WPAC: SHANSHAN - Post-Tropical

[euro6208]

While EURO and GFS shows more robust strengthening...958mb (Tokyo), 911mb (OTS), the HWRF continues to dip.

[euro6208]

000
WTPQ31 PGUM 031009
TCPPQ1

BULLETIN
TROPICAL STORM SHANSHAN (17W) Advisory Number 3
National Weather Service Tiyan GU WP172018
800 PM ChST Fri Aug 3 2018

...TROPICAL STORM SHANSHAN DRIFTING WEST-NORTHWEST...

CHANGES WITH THIS ADVISORY
--------------------------
None.

WATCHES AND WARNINGS
--------------------
A Tropical Storm Warning remains in effect for Agrihan, Pagan and
Alamagan in the Northern CNMI. Tropical storm conditions, including
damaging winds of 39 mph or more, are expected by Saturday morning.

SUMMARY OF 700 PM CHST...0900 UTC...INFORMATION
------------------------------------------------
Location...18.3N 150.2E

About 295 miles east of Agrihan
About 290 miles east of Pagan
About 285 miles east of Alamagan
About 325 miles east-northeast of Anatahan
About 370 miles northeast of Saipan
About 495 miles northeast of Guam

Maximum sustained winds...40 mph
Present movement...WNW...300 degrees at 2 mph

DISCUSSION AND OUTLOOK
----------------------
At 700 PM CHST...0900 UTC...the center of Tropical Storm Shanshan was
located near Latitude 18.3 Degrees North and Longitude 150.2 Degrees
East, drifting west-northwest at 2 mph. A turn to the northwest with
an increase in forward speed is expected overnight, and this motion
will continue through the weekend with a gradual turn to the north
Sunday night and Monday. On this track, Shanshan passes about 215
miles northeast of Agrihan Island early Saturday afternoon.

Maximum sustained winds are 40 mph. Tropical Storm Shanshan is
forecast to intensify steadily, and may become a typhoon by Saturday
evening.

The distribution of tropical storm force winds is quite asymmetric,
extending out to 155 miles southwest of the center, up to 140 miles
to the southeast, but only 70 miles northeast of the center. Out to
the northwest, no tropical storm force winds are yet found.

NEXT ADVISORY
-------------
An intermediate advisory will be issued by the National Weather
Service at 1100 PM this evening, followed by the next scheduled
advisory at 200 AM Saturday morning.

$$

Middlebrooke


000
WTPQ81 PGUM 031041
HLSPQ1

URGENT - IMMEDIATE BROADCAST REQUESTED
TROPICAL STORM SHANSHAN (17W) LOCAL STATEMENT
NATIONAL WEATHER SERVICE TIYAN GU
841 PM CHST FRI AUG 3 2018

...TROPICAL STORM SHANSHAN DRIFTING WEST-NORTHWEST...

.NEW INFORMATION...
NONE.

.AREAS AFFECTED...
THIS LOCAL STATEMENT PROVIDES INFORMATION AND RECOMMENDED ACTIONS FOR
PEOPLE ON AGRIHAN...PAGAN AND ALAMAGAN IN THE COMMONWEALTH OF THE
NORTHERN MARIANAS.

.WATCHES/WARNINGS...
A TROPICAL STORM WARNING REMAINS IN EFFECT FOR PAGAN...AGRIHAN AND
ALAMAGAN IN THE NORTHERN CNMI. TROPICAL STORM CONDITIONS...INCLUDING
DAMAGING WINDS OF 39 MPH OR MORE...ARE EXPECTED SATURDAY MORNING.

.STORM INFORMATION...
AT 700 PM CHST...0900 UTC...THE CENTER OF TROPICAL STORM SHANSHAN WAS
LOCATED NEAR LATITUDE 18.3 DEGREES NORTH AND LONGITUDE 150.2 DEGREES
EAST. THIS IS 295 MILES EAST OF AGRIHAN...290 MILES EAST OF PAGAN...
AND 285 MILES EAST OF ALAMAGAN. SHANSHAN IS DRIFTING WEST-NORTHWEST
AT 2 MPH.

.SITUATION OVERVIEW...
TROPICAL STORM SHANSHAN IS INTENSIFYING AND COULD BECOME A TYPHOON
BY SATURDAY EVENING. SHANSHAN IS MOVING WEST-NORTHWEST...BUT IS
EXPECTED TO TURN NORTHWEST WITH AN INCREASE IN FORWARD SPEED
OVERNIGHT. THIS WILL TAKE SHANSHAN TO WITHIN 215 MILES NORTHEAST OF
AGRIHAN EARLY SATURDAY AFTERNOON. TROPICAL STORM FORCE WINDS ARE
EXPECTED AT AGRIHAN AND PAGAN SATURDAY MORNING...AND AROUND NOON ON
ALAMAGAN.

.NEXT UPDATE...
THE NEXT LOCAL STATEMENT WILL BE ISSUED AT 300 AM SATURDAY MORNING...
OR SOONER IF CONDITIONS WARRANT.

...AGRIHAN...PAGAN AND ALAMAGAN...

.PRECAUTIONARY/PREPAREDNESS ACTIONS...
PEOPLE ON AGRIHAN...PAGAN AND ALAMAGAN SHOULD PREPARE FOR DAMAGING
WINDS AND HEAVY RAIN. SMALL BOATS SHOULD BE SECURED. AVOID INTER-
ISLAND TRAVEL BY BOAT THROUGH MONDAY NIGHT.

...WIND INFORMATION...
NORTHWEST WINDS OF 15 TO 25 MPH WILL SLOWLY SHIFT TO WEST-SOUTHWEST
OVERNIGHT AND INCREASE TO 30 TO 40 MPH WITH GUSTS TO 45 MPH AROUND
700 AM SATURDAY. THESE WINDS WILL SHIFT TO SOUTHWEST AND CONTINUE
THROUGH SATURDAY NIGHT INTO SUNDAY MORNING BEFORE SUBSIDING SUNDAY
AFTERNOON.

...STORM SURGE AND SURF INFORMATION...
SURF WILL BUILD TO BETWEEN 11 AND 13 FEET TONIGHT ALONG NORTH AND
WEST FACING SHORES...THEN BUILD TO BETWEEN 13 TO 15 FEET SATURDAY
ALONG WEST AND SOUTH FACING REEFS. INUNDATION OF 1 TO 2 FEET IS
POSSIBLE ALONG WINDWARD COASTAL AREAS.

...OTHER STORM EFFECTS...
LOCALLY HEAVY DOWNPOURS COULD PRODUCE 4 TO 6 INCHES OF RAIN ON ALL
THREE ISLANDS OVER THE NEXT COUPLE OF DAYS.

$$

MIDDLEBROOKE

[euro6208]

17W SHANSHAN 180803 1200 18.5N 150.1E WPAC 45 989

Looks like JTWC went with 45 knots based on a consensus 3.0.

TPPN11 PGTW 031222

A. TROPICAL STORM 17W (SHANSHAN)

B. 03/1200Z

C. 18.52N

D. 150.02E

E. FIVE/HMWRI8

F. T3.0/3.0/D2.0/24HRS STT: D0.5/03HRS

G. IR/EIR

H. REMARKS: 38A/PBO SBC/ANMTN. CNVCTN WRAPS .60 ON LOG10 SPIRAL
YIELDING A DT OF 3.0. MET AND PT AGREE. DBO DT.

I. ADDITIONAL POSITIONS:
03/0737Z 18.32N 150.42E SSMS
03/1040Z 18.12N 150.18E MMHS


LOWE

[euro6208]

[euro6208]

Taken from another website.

Tropical Storm #Shanshan (#17W) is quickly becoming better organized as it creeps northwestward east of the Northern Mariana Islands. The system has a solid central dense overcast feature with very strong convection and excellent outflow in all quadrants. A recent ASCAT pass only captured the eastern half of the system, but indicated that it has a very large area of tropical storm force winds. A well-established feeder band extends into the ITCZ/monsoon trough to the southwest. Unfortunately most of the high-resolution microwave imagers missed the center on their recent passes so there's no way to evaluate the inner structure of the cyclone at the moment.

Shanshan is located in a very favorable environment, with very light wind shear and SSTs of 30-31 degrees C and very deep heat content. Therefore there is no reason to believe it won't intensify at a very quick pace, and both JMA and JTWC forecast Shanshan to become a typhoon within the next 36 hours as it moves northward through a weakness in the subtropical ridge. At about 48-60 hours, steadily cooling SSTs and slightly increased shear should result in the intensity leveling off or weakening.

After that, well...things get a little weird. One of the biggest complicating factors in forecasting tropical storms in the Western Pacific has been the large upper-level low located northeast of the Philippines, and this feature is what steered Typhoon Jongdari on its strange east-to-west track across Japan. The models finally have this feature moving back west and dissipating over the next few days as the subtropical ridge strengthens. The big question is how quickly that will happen - if it moves away only slowly, as the ECMWF model forecasts, it will pull Shanshan northwest and closer to Japan. If it moves away more quickly, as forecast by the GFS, Shanshan will likely continue on a more northerly track and eventually get caught up in the westerlies east of Japan. There is a high amount of uncertainty in the forecast, and interests in Japan should closely monitor the progress of Shanshan.

[euro6208]

[1900hurricane]

I'd be interested in seeing a microwave pass right about now. Shanshan is still dealing with some light to moderate shear from the north, but very deep convection has developed over the apparent circulation center.

[1900hurricane]

Low and mid level centers still don't look aligned.

[euro6208]

WDPN31 PGTW 032100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (SHANSHAN)
WARNING NR 05//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 17W (SHANSHAN), LOCATED APPROXIMATELY 212 NM EAST
OF AGRIHAN, HAS TRACKED NORTHWESTWARD AT 10 KNOTS OVER THE PAST SIX
HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY REVEALS DEEP
CONVECTION NEAR THE LOW LEVEL CIRCULATION CENTER (LLCC). THE
INITIAL POSITION IS PLACED WITH GOOD CONFIDENCE BASED ON A 031819Z
SSMI/S 91 GHZ MICROWAVE IMAGE SHOWING BANDING FEATURES WRAPPING IN
FROM THE NORTH AND SOUTH, AND DEEP CONVECTION TO THE SOUTHWEST OF
THE LLCC. THE CURRENT INTENSITY IS ASSESSED AT 50 KNOTS BASED ON
DVORAK CURRENT INTENSITY ESTIMATES OF T3.0-T3.5 (45-55 KNOTS) FROM
RJTD, PGTW AND KNES ALONG WITH A 031537Z SATCON ESTIMATE OF 55
KNOTS. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH
LOW (10-15 KNOT) VERTICAL WIND SHEAR, EXCELLENT EQUATORWARD
OUTFLOW, AND GOOD POLEWARD OUTFLOW. TS 17W IS TRACKING ALONG THE
SOUTHWEST PERIPHERY OF A NORTH-SOUTH ORIENTED SUBTROPICAL RIDGE
(STR) TO THE NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 17W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD THROUGH
TAU 72 AS IT TRACKS ALONG THE WESTERN PERIPHERY OF THE STR. THE
SYSTEM IS EXPECTED TO INTENSIFY STEADILY AND PEAK AT 90 KNOTS BY
TAU 72. THE INTENSITY FORECAST IS CONSISTENT WITH THE INTENSITY
GUIDANCE CONSENSUS. NUMERICAL MODEL TRACK GUIDANCE IS IN POOR
AGREEMENT WITH A 400NM SPREAD IN SOLUTIONS AT TAU 72. THE FORECAST
TRACK CLOSELY FOLLOWS THE MULTI-MODEL CONSENSUS WITH LOW CONFIDENCE
FOR THIS PORTION OF THE FORECAST.
C. AFTER TAU 72, TS 17W IS FORECAST TO CONTINUE TRACKING NORTH-
NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF THE STR. FOR THIS
PORTION OF THE FORECAST, THE GUIDANCE SPLITS INTO TWO DISTINCT
SCENARIOS AT THIS POINT. SEVERAL MEMBERS (UKMET, COAMPS, HWRF, AND
GALWEM) PREDICT TS 17W WILL RE-CURVE, TURNING TO THE NORTHEAST AND
ACCELERATING BY TAU 120. OTHER MEMBERS (GFS, NAVGEM, JGSM, AND
ECMWF) SHOW THE TRACK CONTINUING TO THE NORTHWEST TOWARD JAPAN. OF
NOTE, THIS GROUP IS FURTHER SPLIT WITH THE ECMWF AND JGSM PLACING
THE CYCLONE CENTER SOUTH OF KYOTO BY TAU 120 WHILE GFS AND NAVGEM
PLACE THE CYCLONE CENTER NEAR TOKYO BY TAU 120. THIS BIFURCATION
HAS BECOME MORE PRONOUNCED THIS FORECAST CYCLE. ANALYSIS OF NAVGEM
AND GFS FIELDS INDICATES PERSISTENT HIGH ZONAL FLOW THROUGHOUT THE
FORECAST WHILE UKMET DEVELOPS A SHORTWAVE TROUGH SUFFICIENT TO
INDUCE RECURVATURE. THE OFFICIAL JTWC FORECAST TRACK FAVORS THE
GFS/NAVGEM SOLUTION WHILE CLOSELY FOLLOWING THE PREVIOUS JTWC
FORECAST TRACK WITH LOW CONFIDENCE DUE TO HIGH UNCERTAINTY IN THE
GUIDANCE. AFTER TAU 72, TS 17W IS EXPECTED TO WEAKEN GRADUALLY DUE
TO REDUCED POLEWARD OUTFLOW. OVERALL, THERE IS LOW CONFIDENCE IN
THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

TPPN11 PGTW 032146

A. TROPICAL STORM 17W (SHANSHAN)

B. 03/2100Z

C. 19.62N

D. 149.37E

E. THREE/HMWRI8

F. T3.5/3.5/D1.5/24HRS STT: D0.5/03HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 28A/PBO LRG CDO/ANMTN. IRREG CDO >90NM W/ 0.5 ADDED
FOR SMALL BANDING FEATURE YIELDS DT OF 3.5. MET YIELDS 3.0 WITH
PT ADJUSTMENT TO 3.5. DBO DT.

I. ADDITIONAL POSITIONS: NONE


RICHARDSON


TXPQ29 KNES 032118
TCSWNP

A. 17W (SHANSHAN)

B. 03/2030Z

C. 19.5N

D. 149.3E

E. THREE/HIMAWARI-8

F. T3.5/3.5/D1.5/24HRS

G. IR/EIR/SWIR/SSMIS

H. REMARKS...THIS INTENSITY ESTIMATE WAS DERIVED USING 4 KM IR DATA. 9/10
BANDING RESULTS IN A DT OF 3.5. MET AND PT ARE 3.5. FT IS BASED ON DT.

I. ADDL POSITIONS

03/2011Z 19.5N 149.3E SSMIS


...ZHU

[1900hurricane]

JMA has Shanshan as a severe tropical storm now.

[1900hurricane]

A partial ASCAT pass shows that Shanshan's low and mid level centers now appear to be much better lined up. The pass also revealed a 50 kt wind vector, so the system may be approaching typhoon intensity, although structure still isn't anything to write home about.

[Alyono]

this has the markings of a massive Japanese typhoon

[Twisted-core]

https://imgur.com/hqdaR8X


Looking v/good atm when it wraps thoroughly should go on to become the next super typhoon for the season.

[doomhaMwx]

JMA landfall near Tokyo, while JTWC farther east.

[euro6208]

WDPN31 PGTW 040300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (SHANSHAN) WARNING
NR 06//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 17W (SHANSHAN), LOCATED APPROXIMATELY 213 NM EAST-
NORTHEAST OF AGRIHAN, HAS TRACKED NORTH-NORTHWESTWARD AT 08 KNOTS
OVER THE PAST SIX HOURS. THE INITIAL POSITION IS PLACED WITH GOOD
CONFIDENCE BASED ON ANIMATED MULTISPECTRAL (MSI) SATELLITE IMAGERY
WHICH REVEALS DEEP CONVECTION WRAPPING AROUND THE LOW LEVEL
CIRCULATION CENTER (LLCC), PRIMARILY FROM THE SOUTH. THE MSI IMAGERY
ALSO REVEALS SOME DRIER AIR ENTRAINING INTO THE CIRCULATION FROM THE
WEST. THE INTENSITY IS ASSESSED AT 55 KNOTS BASED ON DVORAK CURRENT
INTENSITY ESTIMATES OF T3.5 (55 KNOTS) FROM RJTD, PGTW AND KNES.
ALSO, A PARTIAL 032311Z METOP-B ASCAT PASS SHOWS A LARGE AREA OF 35
KT WINDS TO THE SOUTH AND AN AREA OF 45 KNOT WINDS TO THE EAST OF
THE LLCC. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH
LOW (5-10 KNOT) VERTICAL WIND SHEAR, EXCELLENT EQUATORWARD OUTFLOW,
AND GOOD POLEWARD OUTFLOW. TS 17W IS TRACKING ALONG THE SOUTHWEST
PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 17W IS FORECAST TO CONTINUE A NORTH-NORTHWESTWARD TRACK
ALONG THE WESTERN PERIPHERY OF THE STR THROUGH TAU 72. ENVIRONMENTAL
CONDITIONS ARE EXPECTED TO REMAIN FAVORABLE AND, FOLLOWING THE
CONSENSUS OF THE INTENSITY GUIDANCE, THE SYSTEM IS FORECASTED TO
INTENSIFY TO 90 KNOTS BY TAU 48. NUMERICAL MODEL TRACK GUIDANCE
REMAINS IN POOR AGREEMENT WITH OVER 400NM OF SPREAD AT TAU 72. FOR
THIS PORTION OF THE FORECAST, THE OFFICIAL TRACK CLOSELY FOLLOWS THE
MULTI-MODEL CONSENSUS WITH LOW CONFIDENCE.
C. AFTER TAU 72, TS 17W IS FORECAST TO CONTINUE A NORTH-
NORTHWESTWARD TRACK ALONG THE WESTERN PERIPHERY OF THE STR. DURING
THIS PERIOD, THE GUIDANCE SPLITS INTO TWO DISTINCT SCENARIOS.
SEVERAL MEMBERS (UKMET, COAMPS, HWRF, NAVGEM, AND GALWEM) PREDICT TS
17W WILL RE-CURVE NORTHEASTWARD AND ACCELERATE BY TAU 120. OTHER
MEMBERS (GFS, JGSM, AND ECMWF) SHOW THE TRACK CONTINUING TO THE
NORTHWEST TOWARD JAPAN. OF NOTE, NAVGEM HAS JOINED THE MEMBERS THAT
SHOW THE RECURVE TRACK. THE NAVGEM SOLUTION CHANGED BECAUSE OF A
SHORTWAVE TROUGH THAT WEAKENS THE STR SUFFICIENTLY TO ALLOW THE
CYCLONE TO MOVE POLEWARD OF THE RIDGE AXIS AND INTO THE MIDLATITUDE
WESTERLIES. THROUGHOUT THIS PORTION OF THE FORECAST, TS 17W IS
EXPECTED TO EXPERIENCE REDUCED POLEWARD OUTFLOW AND WEAKEN
GRADUALLY. THE OFFICIAL JTWC FORECAST TRACK CLOSELY FOLLOWS THE
PREVIOUS JTWC FORECAST TRACK, ON THE SOUTHWESTERN SIDE OF THE
MEMBERS THAT RECURVE THE SYSTEM, WITH LOW CONFIDENCE.//
NNNN

[euro6208]

[xtyphooncyclonex]

TY 1813 (Shanshan)
Issued at 06:50 UTC, 4 August 2018

<Analysis at 06 UTC, 4 August>
Scale -
Intensity Strong
Center position N20°55' (20.9°)
E148°40' (148.7°)
Direction and speed of movement NNW 20 km/h (10 kt)
Central pressure 975 hPa
Maximum wind speed near center 35 m/s (65 kt)
Maximum wind gust speed 50 m/s (95 kt)
≥ 50 kt wind area ALL 90 km (50 NM)
≥ 30 kt wind area S 560 km (300 NM)
N 280 km (150 NM)

<Forecast for 18 UTC, 4 August>
Intensity Strong
Center position of probability circle N22°25' (22.4°)
E147°30' (147.5°)
Direction and speed of movement NW 15 km/h (9 kt)
Central pressure 975 hPa
Maximum wind speed near center 35 m/s (65 kt)
Maximum wind gust speed 50 m/s (95 kt)
Radius of probability circle 60 km (30 NM)
Storm warning area ALL 150 km (80 NM)

<Forecast for 06 UTC, 5 August>
Intensity Strong
Center position of probability circle N24°05' (24.1°)
E146°35' (146.6°)
Direction and speed of movement NNW 15 km/h (9 kt)
Central pressure 970 hPa
Maximum wind speed near center 35 m/s (70 kt)
Maximum wind gust speed 50 m/s (100 kt)
Radius of probability circle 90 km (50 NM)
Storm warning area ALL 190 km (100 NM)

<Forecast for 06 UTC, 6 August>
Intensity Strong
Center position of probability circle N27°30' (27.5°)
E144°40' (144.7°)
Direction and speed of movement NNW 20 km/h (10 kt)
Central pressure 955 hPa
Maximum wind speed near center 40 m/s (80 kt)
Maximum wind gust speed 60 m/s (115 kt)
Radius of probability circle 180 km (95 NM)
Storm warning area ALL 310 km (170 NM)

<Forecast for 06 UTC, 7 August>
Intensity Strong
Center position of probability circle N30°35' (30.6°)
E142°40' (142.7°)
Direction and speed of movement NNW 15 km/h (9 kt)
Central pressure 965 hPa
Maximum wind speed near center 40 m/s (75 kt)
Maximum wind gust speed 55 m/s (105 kt)
Radius of probability circle 240 km (130 NM)
Storm warning area ALL 370 km (200 NM)

[cycloneye]

WDPN31 PGTW 040900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 17W (SHANSHAN) WARNING
NR 07//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON 17W (SHANSHAN), LOCATED APPROXIMATELY 212 NM NORTHEAST OF
AGRIHAN, HAS TRACKED NORTH-NORTHWESTWARD AT 08 KNOTS OVER THE
PAST SIX HOURS. THE INITIAL POSITION IS PLACED WITH GOOD CONFIDENCE
BASED ON ANIMATED MULTISPECTRAL (MSI) SATELLITE IMAGERY AND A
MICROWAVE EYE FEATURE IN A 040533Z SSMIS 91GHZ MICROWAVE IMAGE. THE
INTENSITY IS ASSESSED AT 65 KNOTS BASED ON DVORAK CURRENT INTENSITY
ESTIMATES OF T4.0 (65 KNOTS) FROM RJTD AND PGTW, AND IS SLIGHTLY
UNDER THE 040556Z SATCON ESTIMATE OF 70 KTS. AN EYE IS
INTERMITTENTLY VISIBLE IN ENHANCED INFRARED SATELLITE IMAGERY, AND
DEEP CONVECTIVE RAINBANDS ARE WRAPPING IN PRIMARILY FROM THE SOUTH.
UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH LOW (5-10
KNOT) VERTICAL WIND SHEAR, EXCELLENT EQUATORWARD OUTFLOW, AND
MARGINAL POLEWARD OUTFLOW. TY 17W IS TRACKING ALONG THE SOUTHWEST
PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TY 17W IS FORECAST TO CONTINUE A NORTH-NORTHWESTWARD TRACK
ALONG THE WESTERN PERIPHERY OF THE STR THROUGH TAU 72. ENVIRONMENTAL
CONDITIONS ARE EXPECTED TO REMAIN FAVORABLE AND POLEWARD OUTFLOW IS
EXPECTED TO INCREASE IN THE NEAR-TERM, ALLOWING THE SYSTEM TO REACH
A PEAK INTENSITY OF 95 KTS BY TAU 48. NUMERICAL MODEL TRACK GUIDANCE
REMAINS IN POOR AGREEMENT WITH OVER 250NM OF SPREAD AT TAU 72. FOR
THIS PORTION OF THE FORECAST, THE OFFICIAL TRACK CLOSELY FOLLOWS THE
MULTI-MODEL CONSENSUS WITH LOW CONFIDENCE.
C. AFTER TAU 72, TY 17W IS FORECAST TO CONTINUE A NORTH-
NORTHWESTWARD TRACK ALONG THE WESTERN PERIPHERY OF THE STR. ALL
MODELS PORTRAY A SHORTWAVE TROUGH MOVING THROUGH THE AREA AROUND TAU
72. THE MODELS DIFFER IN THE DEGREE TO WHICH THE SHORTWAVE TROUGH
WEAKENS THE STR AND ALLOWS 17W TO MOVE POLEWARD OF THE RIDGE AXIS
AND BE CAPTURED BY THE MIDLATITUDE WESTERLIES. DURING THIS PERIOD,
THE GUIDANCE SPLITS INTO TWO DISTINCT SCENARIOS. SEVERAL MEMBERS
(UKMET, COAMPS, HWRF, NAVGEM, AND GALWEM) PREDICT TY 17W WILL
RECURVE NORTHEASTWARD AND ACCELERATE BY TAU 120. OTHER MEMBERS (GFS,
JGSM, ECMWF, AND HWRF) SHOW THE TRACK CONTINUING TO THE NORTHWEST
TOWARD JAPAN, THEN RECURVING, POTENTIALLY AFTER HAVING MADE
LANDFALL. HWRF HAS SHIFTED FROM THE RECURVING SOLUTION TO THE MORE
NORTHWESTWARD SOLUTION MOVING OVERLAND ONTO JAPAN DURING THE MOST
RECENT MODEL RUN, ALTHOUGH JGSM HAS MOVED CLOSER TO CONSENSUS DURING
THE MOST RECENT MODEL RUN. THE LATEST ECMWF MODEL RUN IS THE MOST
SIGNIFICANT WESTERN OUTLIER, AND STICKS CLOSE TO THE PREVIOUS MODEL
RUN TRACK, DEPICTING A MORE WEST-NORTHWESTWARD JOG THROUGH TAU 120.
THROUGHOUT THIS PORTION OF THE FORECAST, TY 17W IS EXPECTED TO
EXPERIENCE REDUCED POLEWARD OUTFLOW AND MOVE INTO AN AREA OF COOLER
SSTS (26 DEGREES C OR COOLER) AND WEAKEN GRADUALLY. THE JTWC
INTENSITY FORECAST IS HEDGED ABOVE THE INTENSITY CONSENSUS, AS LATE-
TERM INTENSITY WILL BE SIGNIFICANTLY IMPACTED BY PROXIMITY TO LAND
OR LANDFALL, DEPENDING ON THE MODEL TRACK. THE OFFICIAL JTWC
FORECAST TRACK IS HEDGED TO THE SOUTHWESTERN SIDE OF THE MEMBERS
THAT RECURVE THE SYSTEM, WITH LOW CONFIDENCE.//
NNNN

[euro6208]

TPPN11 PGTW 040924

A. TYPHOON 17W (SHANSHAN)

B. 04/0900Z

C. 21.34N

D. 148.51E

E. THREE/HMWRI8

F. T4.0/4.0/D1.5/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 13A/PBO TIGHTLY CURVED BNDG/ANMTN. LLCC EMBEDDED IN
OW YIELDS A 3.5 +0.5 FOR BANDING FEATURE YIELDS A DT OF 4.0. PT
AGREES WITH DT WHILE MET YIELDS A 3.5. DBO DT.

I. ADDITIONAL POSITIONS:
04/0339Z 20.80N 148.87E ATMS
04/0421Z 20.97N 148.77E SSMI
04/0533Z 20.78N 148.82E SSMS
04/0558Z 20.87N 148.78E MMHS


LEMBKE

TXPQ28 KNES 040908
TCSWNP

A. 17W (SHANSHAN)

B. 04/0830Z

C. 21.4N

D. 148.5E

E. ONE/HIMAWARI-8

F. T4.5/4.5/D1.5/24HRS

G. IR/EIR/VIS

H. REMARKS...THIS INTENSITY ESTIMATE WAS DERIVED USING 4 KM IR DATA. MG
EYE IS EMBEDDED IN DG FOR AN ENO OF 4.5 AND SURROUNDED BY B FOR AN EADJ
OF 0 RESULTING IN A DT OF 4.5. PT AGREES WHILE MET IS 4.0 BASED ON 24
HOUR DEVELOPMENT TREND. FT IS BASED ON DT.

I. ADDL POSITIONS

NIL


...TURK