WPAC: SANVU - Post-Tropical

[senorpepr]

JMA calling it a tropical storm:

WTPQ20 RJTD 280600
RSMC TROPICAL CYCLONE ADVISORY
NAME TS 1715 SANVU (1715) UPGRADED FROM TD
ANALYSIS
PSTN 280600UTC 19.7N 146.9E FAIR
MOVE NNW SLOWLY
PRES 994HPA
MXWD 035KT
GUST 050KT
30KT 180NM
FORECAST
24HF 290600UTC 22.9N 146.9E 60NM 70%
MOVE N 08KT
PRES 980HPA
MXWD 050KT
GUST 070KT
48HF 300600UTC 25.9N 145.7E 95NM 70%
MOVE NNW 08KT
PRES 975HPA
MXWD 055KT
GUST 080KT
72HF 310600UTC 28.2N 144.8E 130NM 70%
MOVE NNW 06KT
PRES 970HPA
MXWD 060KT
GUST 085KT =

WTJP21 RJTD 280600
WARNING 280600.
WARNING VALID 290600.
WARNING IS UPDATED EVERY 6 HOURS.
STORM WARNING.
TROPICAL STORM 1715 SANVU (1715) UPGRADED FROM TROPICAL DEPRESSION
994 HPA
AT 19.7N 146.9E MARIANAS MOVING NORTHNORTHWEST SLOWLY.
POSITION FAIR.
MAX WINDS 35 KNOTS NEAR CENTER.
RADIUS OF OVER 30 KNOT WINDS 180 MILES.
FORECAST POSITION FOR 290600UTC AT 22.9N 146.9E WITH 60 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.
980 HPA, MAX WINDS 50 KNOTS NEAR CENTER.
EXTENDED OUTLOOK.
FORECAST POSITION FOR 300600UTC AT 25.9N 145.7E WITH 95 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.
975 HPA, MAX WINDS 55 KNOTS NEAR CENTER.
FORECAST POSITION FOR 310600UTC AT 28.2N 144.8E WITH 130 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.
970 HPA, MAX WINDS 60 KNOTS NEAR CENTER.

JAPAN METEOROLOGICAL AGENCY.=

[euro6208]

WTPN21 PGTW 280600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/270552Z AUG 17//
AMPN/REF IS TROPICAL CYCLONE FORMATION ALERT (WTPN21 PGTW 270600)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
200 NM EITHER SIDE OF A LINE FROM 19.7N 145.5E TO 25.6N 146.0E
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 25 TO 30 KNOTS. METSAT IMAGERY AT
280530Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 20.0N
145.5E. THE SYSTEM IS MOVING NORTHWARD AT 03 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED
NEAR 18.9N 145.6E IS NOW LOCATED NEAR 20.0N 145.5E, APPROXIMATELY
370NM SOUTHEAST OF IWO TO. THIS SYSTEM IS CLASSIFIED AS A MONSOON
DEPRESSION AND CURRENTLY LACKS A DEFINED CENTER. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY DEPICTS A SLOWLY-CONSOLIDATING
MONSOON DEPRESSION WITH DEEP CONVECTIVE BANDING ALONG THE SOUTH AND
SOUTHEAST QUADRANTS ASSOCIATED WITH CONVERGENT, STRENGTHENING
SOUTHWESTERLY FLOW. DESPITE PERSISTENT DEEP CONVECTION, A 280007Z
AMSU 89GHZ IMAGE INDICATES FRAGMENTED, WEAK CONVECTIVE BANDING AND
AN ILL-DEFINED LOW-LEVEL CIRCULATION CENTER. A 280010Z PARTIAL ASCAT
IMAGE SHOWS 25 TO 30 KNOT WINDS OVER THE SOUTHEAST PERIPHERY AND
NORTHERN PERIPHERY BUT WEAKER WINDS ELSEWHERE (GENERALLY 20 KNOTS OR
LOWER). SURFACE OBSERVATIONS FROM GUAM AND SAIPAN, WITHIN THE
SOUTHWESTERLY MONSOONAL FLOW, INDICATE SUSTAINED WINDS OF 15 TO 20
KNOTS WITH GUSTS RANGING FROM 25 TO 30 KNOTS. UPPER-LEVEL ANALYSIS
INDICATES THE MONSOON DEPRESSION IS LOCATED IN A FAVORABLE
ENVIRONMENT WITH LOW VERTICAL WIND SHEAR, GOOD POLEWARD AND
EQUATORWARD OUTFLOW, AND WARM SST (29-30C). DYNAMIC MODELS ARE IN
AGREEMENT THAT THE SYSTEM WILL CONTINUE TO DEEPEN WITH PERIPHERAL
WINDS INCREASING TO GALE FORCE LEVELS AS THE SYSTEM TRACKS SLOWLY
NORTHWARD OVER THE NEXT TWO DAYS. BASED ON RECENT ASCAT DATA AND
SURFACE OBSERVATIONS, MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED
AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE
NEAR 1000 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS HIGH. THIS
SUPERSEDES REF A.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
290600Z.//
NNNN

[euro6208]

.Marianas Synopsis...
The tropical disturbance is north of Agrihan near 20N146E this
evening. Fresh to strong monsoonal southwest winds can be seen from
Guam northward to Saipan, strong southwest winds over the northern
CNMI. Widespread deep convection continues to flare up over the
northern CNMI. Sporadic convection is present near Saipan and Tinian,
while only isolated showers are over Guam and Rota.

&&

.Discussion...
Converging moist southwesterly flow along with the diurnal cycle
will maintain showery conditions and thunderstorms near Saipan and
Tinian, and also spread them southward over Rota and Guam later
tonight. As the tropical disturbance drifts farther northward away
from the northern CNMI Tuesday and Tuesday night, it will allow a
surface ridge just southeast of Guam to shift northward. Drier air
associated with this ridge should gradually bring improvement to Guam
by Tuesday afternoon and then spread northward to Saipan by Tuesday
evening. Residual converging southwest winds might still spark a few
showers and thunderstorms on Wednesday but fair weather should return
to the Marianas by Wednesday afternoon. Both GFS and ECMWF models are
forming a secondary circulation along the monsoon tail feeding toward
the tropical disturbance, somewhere near Minami Tori Shima after
midweek. This can re-establish the convergent wind flow across our
forecast area. Decided not to include this scenario into the mid-
term forecast as there are still uncertainty.

&&

[1900hurricane]

Sanvu could have some real potential if it was 10º further south.

[euro6208]

WDPN31 PGTW 282100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (SANVU) WARNING NR 02//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 17W (SANVU), 400 NM SOUTHEAST OF IWO TO,
JAPAN, HAS TRACKED NORTHEASTWARD AT 06 KNOTS OVER THE PAST SIX HOURS.
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A SLOWLY
CONSOLIDATING SYSTEM WITH THE MAIN FEEDER BANDS TRAILING THE LOW
LEVEL CIRCULATION (LLC) SOUTHWESTWARD, AND PARTIALLY EXPOSING THE
LLC. THE SYSTEM REMAINS EXPANSIVE, COVERING MORE THAN 20 DEGREES OF
LATITUDE, WITH MONSOON DEPRESSION CHARACTERISTICS. THE INITIAL
POSITION IS BASED ON THE EIR LOOP AND ON A LOW REFLECTIVITY
CIRCULATION FEATURE IN THE 281826Z 89 GHZ GPM MICROWAVE PASS WITH
FAIR CONFIDENCE. THE INITIAL INTENSITY OF 35 KNOTS IS BASED ON AN
OVERALL ASSESSMENT OF AGENCY AND OBJECTIVE DVORAK ESTIMATES AND
REFLECTS THE IMPROVED STATE OF THE SYSTEM. UPPER LEVEL ANALYSIS
INDICATES TS 17W IS IN AN AREA OF MODERATE (15-20 KNOT) VERTICAL WIND
SHEAR (VWS) THAT IS MOSTLY OFFSET BY STRONG POLEWARD AND EQUATORWARD
OUTFLOW. ADDITIONALLY, ALONG-TRACK SEA SURFACE TEMPERATURES (SST) ARE
HIGHLY CONDUCIVE AT 30-31 CELSIUS. THE CYCLONE IS CURRENTLY TRACKING
ALONG THE NORTHWEST PERIPHERY OF THE NEAR EQUATORIAL RIDGE TO THE
SOUTHEAST.
3. FORECAST REASONING.
A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 17W IS FORECAST TO ACCELERATE NORTHWARD THEN NORTHWESTWARD
AS THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST ASSUMES STEERING AND
BUILDS. AFTER TAU 48, IT WILL BEGIN TO ROUND THE WESTERN EDGE OF THE
STR AND TRACK MORE POLEWARD. THE FAVORABLE ENVIRONMENTAL CONDITIONS
WILL PERSIST AND PROMOTE STEADY INTENSIFICATION, PEAKING AT 80 KNOTS
BY TAU 72. THE AVAILABLE NUMERIC GUIDANCE IS IN GOOD AGREEMENT WITH
JGSM AND JENS ON THE LEFT SIDE OF A NARROWLY-SPREAD MODEL ENVELOPE.
THE JTWC TRACK IS LAID JUST TO THE RIGHT OF CONW TO OFFSET THE
UNLIKELY JGSM/JENS TRACK SOLUTION. THERE IS FAIR CONFIDENCE IN THIS
PORTION OF THE JTWC TRACK FORECAST.
C. IN THE EXTENDED PERIOD, TS SANVU IS FORECAST TO ACCELERATE
NORTHEASTWARD ON THE POLEWARD SIDE OF THE STR AND GET EMBEDDED IN THE
MID-LATITUDE TROUGH. SSTS WILL REMAIN WARM, HOWEVER, INCREASING VWS
WILL BE THE PRIMARY FACTOR IN THE GRADUAL WEAKENING OF THE SYSTEM.
CONCURRENTLY, THE SYSTEM WILL BEGIN EXTRA-TROPICAL TRANSITION AS IT
TRACKS DEEPER INTO THE BAROCLINIC ZONE. BY TAU 120, TS 17W WILL BE
REDUCED TO A 50-KNOT SYSTEM WITH AN EXPANDING WIND FIELD AND COOLING
CORE AS IT ASSUMES EXTRA-TROPICAL CHARACTERISTICS. THE NUMERIC
GUIDANCE BECOMES MORE SPREAD, LENDING LOW CONFIDENCE IN THIS PORTION
OF THE JTWC TRACK FORECAST.//
NNNN

[euro6208]

It's gigantic...

[euro6208]

Since it's moving north and away from the area, no warnings and watches are in place for Guam and the Northern Marianas.

000
WTPQ31 PGUM 282108
TCPPQ1

BULLETIN
TROPICAL STORM SANVU (17W) ADVISORY NUMBER 2
NATIONAL WEATHER SERVICE TIYAN GU WP172017
800 AM ChST Tue Aug 29 2017

...Sanvu now a tropical storm...

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

WATCHES AND WARNINGS
--------------------
None.

SUMMARY OF 700 AM CHST...2100 UTC...INFORMATION
-----------------------------------------------
Location...21.1N 147.1E

About 185 miles north-northeast of Agrihan
About 425 miles north of Saipan
About 550 miles north-northeast of Guam

Maximum sustained winds...40 mph
Present movement...northeast...050 degrees at 7 mph

DISCUSSION AND OUTLOOK
----------------------
At 700 AM CHST...2100 UTC...the center of Tropical Storm Sanvu was
located near Latitude 21.1 North and Longitude 147.1 East. Sanvu is
moving northeastward at 7 mph and is expected to turn more to the
north then northwest today and tonight before gradually turning back
to the north Wednesday. Sanvu will slightly increase in forward
speed today and tonight.

Maximum sustained winds have increased to 40 mph. Tropical Storm
Sanvu will slowly continue to intensify the next couple of days.

Tropical storm force winds extend outward up to 235 miles from the
center of the storm.

NEXT ADVISORY
-------------
The next scheduled advisory will be issued by the National Weather
Service at 200 PM this afternoon.

$$

W. Aydlett

[euro6208]

000
WWMY80 PGUM 282346
SPSMY

Special Weather Statement
National Weather Service Tiyan GU
915 AM ChST Tue Aug 29 2017

.Overview...Sanvu is now a Tropical Storm about 185 miles north-
northeast of Agrihan and 225 miles north-northeast of Pagan in
the northern CNMI at 21N147E and moving slowly away northward.


GUZ001>004-290815-
Guam-Rota-Tinian-Saipan-
915 AM ChST Tue Aug 29 2017

Southwesterly monsoon flow feeding toward Tropical Storm Sanvu
will continue to bring periods of showers and thunderstorms
through the day particularly over Tinian and Saipan. Winds of 15
to 25 mph are expected through early Wednesday morning. Frequent
gusts to 35 mph and combined seas of 8 to 10 feet will continue
near Saipan and Tinian today.

Mariners operating small craft should remain in port as conditions
will be hazardous for small craft at least through early Wednesday
morning. Mariners operating small vessels should be prepared for
choppy seas and strong winds. Beach goers and swimmers should stay
close to shore and immediately move indoors if lightning is
present.

$$

GUZ005-290815-
Alamagan-Pagan-Agrihan-
915 AM ChST Tue Aug 29 2017

Converging monsoon winds south of Tropical Storm Sanvu will cause
heavy showers and some thunderstorms through Wednesday. Winds of
25 to 35 mph with gusts to 45 mph near showers will persist
through Wednesday morning.

If you are planning any outdoor activities through Wednesday, be
alert for hazardous weather and aware of current conditions and be
prepared to move indoors. Mariners operating small vessels should be
prepared for strong winds and seas of 9 to 11 feet. Small craft
should remain in port as these conditions will be hazardous for their
operation.

$$

Stay tuned to the latest statements and advisories from the
National Weather Service and local emergency management offices.
Products issued by the National Weather Service are posted on the
WFO Guam web page at www.prh.noaa.gov/guam.

$$

Simpson/Guard

[euro6208]

[1900hurricane]

Reminds me somewhat of Omais '16 in terms of scale. Interesting to see guidance trying to max it out near 30ºN.

[euro6208]

40 knots.

WDPN31 PGTW 290300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (SANVU) WARNING NR
03//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 17W (SANVU), 402 NM EAST-SOUTHEAST OF IWO TO,
JAPAN, HAS TRACKED NORTHEASTWARD AT 11 KNOTS OVER THE PAST SIX HOURS.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A CONSOLIDATING
SYSTEM WITH THE MAIN FEEDER BANDS WRAPPING FROM THE SOUTHWEST INTO A
PARTIALLY EXPOSED LLC. THE SYSTEM REMAINS EXPANSIVE, COVERING
MORE THAN 20 DEGREES OF LATITUDE WHICH IS TYPICAL OF A MONSOON
DEPRESSION. THE INITIAL POSITION IS BASED ON THE MSI LOOP AND ON A
LOW REFLECTIVITY CIRCULATION FEATURE IN THE 282346ZZ AMSU-B MICROWAVE
PASS WITH FAIR CONFIDENCE. THE INITIAL INTENSITY OF 40 KNOTS IS BASED
ON AN OVERALL ASSESSMENT OF AGENCY AND OBJECTIVE DVORAK ESTIMATES AND
REFLECTS THE IMPROVED STATE OF THE SYSTEM. UPPER LEVEL ANALYSIS
INDICATES TS 17W IS IN AN AREA OF MODERATE (15-20 KNOT) VERTICAL WIND
SHEAR (VWS) THAT IS MOSTLY OFFSET BY STRONG POLEWARD AND EQUATORWARD
OUTFLOW. ADDITIONALLY, ALONG-TRACK SEA SURFACE TEMPERATURES (SST) ARE
HIGHLY CONDUCIVE AT 30-31 CELSIUS. THE CYCLONE IS CURRENTLY TRACKING
ALONG THE NORTHWEST PERIPHERY OF THE NEAR EQUATORIAL RIDGE TO THE
SOUTHEAST.
3. FORECAST REASONING.
A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 17W IS FORECAST TO MORE NORTHWARD THEN NORTHWESTWARD
AS THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST ASSUMES STEERING AND
BUILDS. AFTER TAU 48, IT WILL ROUND THE WESTERN EDGE OF THE STR AND
TRACK MORE NORTHEASTWARD. THE FAVORABLE ENVIRONMENTAL CONDITIONS
WILL PERSIST AND PROMOTE STEADY INTENSIFICATION, PEAKING AT 80 KNOTS
BY TAU 72.
C. IN THE EXTENDED PERIOD, TS SANVU IS FORECAST TO ACCELERATE
NORTHEASTWARD ON THE POLEWARD SIDE OF THE STR AND GET EMBEDDED IN THE
MID-LATITUDE TROUGH. SSTS WILL REMAIN WARM, HOWEVER, INCREASING VWS
WILL BE THE PRIMARY FACTOR IN THE GRADUAL WEAKENING OF THE SYSTEM.
CONCURRENTLY, THE SYSTEM WILL BEGIN EXTRA-TROPICAL TRANSITION AS IT
TRACKS DEEPER INTO THE BAROCLINIC ZONE. BY TAU 120, TS 17W WILL BE
REDUCED TO A 50-KNOT SYSTEM WITH AN EXPANDING WIND FIELD AND A
COOLING CORE AS IT ASSUMES EXTRA-TROPICAL CHARACTERISTICS. THE
AVAILABLE NUMERIC GUIDANCE IS IN GOOD AGREEMENT WITH JGSM AND JENS ON
THE LEFT SIDE OF A NARROWLY-SPREAD MODEL ENVELOPE. THE JTWC TRACK IS
LAID JUST TO THE RIGHT OF AND SLIGHTLY FASTER THAN CONW TO OFFSET THE
UNLIKELY JGSM/JENS TRACK SOLUTION. THERE IS FAIR CONFIDENCE IN THE
JTWC TRACK FORECAST.//
NNNN

[euro6208]

45 knots...

WDPN31 PGTW 290900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (SANVU) WARNING NR
04//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 17W (SANVU), LOCATED APPROXIMATELY 260 NM NORTH-
NORTHEAST OF AGRIHAN, HAS TRACKED NORTHWARD AT 11 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
SHOWS AN ELONGATED SYSTEM WITH A LARGE MAIN FEEDER BAND WRAPPING
INTO A CONSOLIDATING LLCC FROM THE SOUTHWEST. THE FEEDER BAND MAKES
THE SYSTEM LARGE, SPANNING OVER 20 DEGREES OF LATITUDE. THE INITIAL
POSITION IS PLACED WITH LOW CONFIDENCE BASED ON THE ANIMATED
MULTISPECTRAL LOOP AND A 290534Z SSMIS 91 GHZ MICROWAVE IMAGE
SHOWING A BROAD CIRCULATION. THE INITIAL INTENSITY ESTIMATE OF 45
KNOTS IS BASED ON MULTI AGENCY DVORAK INTENSITY ESTIMATES OF T3.0
(45 KNOTS) FROM PGTW AND RJTD. ENVIRONMENTAL ANALYSIS REVEALS TS 17W
IS IN AN AREA OF HIGH (20-25 KNOT) VERTICAL WIND SHEAR (VWS) THAT IS
BEING OFFSET BY STRONG POLEWARD AND EQUATORWARD OUTFLOW CHANNELS AND
WARM (30 CELSIUS) SEA SURFACE TEMPERATURES (SST) ALONG THE SYSTEM
TRACK. TS SANVU IS CURRENTLY TRACKING TO THE NORTH AS THE PRIMARY
STEERING FEATURE SHIFTS FROM THE NEAR EQUATORIAL RIDGE TO THE SUB
TROPICAL RIDGE (STR) LOCATED TO THE NORTHEAST OF THE SYSTEM.
3. FORECAST REASONING.
A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 17W IS FORECAST TO TRACK NORTHWEST AS THE SUBTROPICAL RIDGE
LOCATED TO THE NORTHEAST TAKES OVER AS THE PRIMARY STEERING FEATURE.
THE SYSTEM WILL TRACK TO THE NORTHWEST AS IT ROUNDS THE SOUTHWESTERN
EXTENT OF THE STR THROUGH TAU 24. BY TAU 36 TS SANVU WILL ROUND THE
WESTERN EXTENT OF THE STR AND RECURVE BACK TO THE NORTHEAST.
FAVORABLE ENVIRONMENTAL CONDITIONS WILL ALLOW FOR CONTINUED
DEVELOPMENT, REACHING A PEAK INTENSITY OF 80 KNOTS BY TAU 72.
DYNAMIC MODEL GUIDANCE IS IN STRONG AGREEMENT THROUGH THE FIRST 24
HOURS LENDING HIGH CONFIDENCE IN THE FIRST 24 HOURS OF THE TRACK
FORECAST. AS THE SYSTEM BEGINS TO RECURVE THE TRACKS DIVERGE WITH
SOME MODELS TURNING THE SYSTEM SOONER THAN OTHERS. DESPITE THE
DIVERGENCE IN MODEL GUIDANCE THERE IS HIGH CONFIDENCE IN THIS
PORTION OF THE JTWC TRACK FORECAST.
C. AFTER TAU 72, TS SANVU WILL TRACK NORTHEASTWARD ON THE
POLEWARD SIDE OF THE STR AND GRADUALLY ACCELERATE. THE SYSTEM WILL
BECOME EMBEDDED IN THE MID-LATITUDE TROUGH AND BEGIN EXTRA-TROPICAL
TRANSITION (ETT). THE ENVIRONMENT WILL BECOME UNFAVORABLE WITH
HIGHER VERTICAL WIND SHEER CAUSING THE STORM TO GRADUALLY WEAKEN AS
IT BEGINS ETT. BY TAU 120, TS 17W WILL WEAKEN TO A 50-KNOT SYSTEM
THAT HAS EXTRA-TROPICAL CHARACTERISTICS. DYNAMIC MODEL GUIDANCE IS
IN GOOD AGREEMENT THAT THE SYSTEM WILL TRACK TO THE NORTHEAST,
HOWEVER, DUE TO VARIATIONS IN THE RECURVE TIMING, THERE IS A LARGE
SPREAD IN THE TRACK LOCATION FROM TAU 72 TO TAU 120. NAVGEM AND
COAMPS-TC HAVE TS 17W TRACKING ON THE EASTERN SIDE OF THE MODEL
SPREAD WITH JGSM AND JENS ON THE WESTERN EXTENT OF THE SPREAD. DUE
TO THE LARGE DIFFERENCE IN MODEL SOLUTIONS, THERE IS LOW CONFIDENCE
IN THIS PORTION OF THE JTWC TRACK FORECAST. //
NNNN

[euro6208]

Even the conservative JMA peaks Sanvu at 949mb. NAVGEM at 956mb. EURO at 961mb, and GFS at 934 mb down from the 00Z low of 918mb.

[euro6208]

WDPN31 PGTW 292100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (SANVU) WARNING NR
06//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 17W (SANVU), LOCATED APPROXIMATELY 197 NM EAST-
SOUTHEAST OF CHICHI JIMA, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD
AT 24 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY SHOWS THE STRONGEST CONVECTION TO THE NORTHEAST OF
THE LOW LEVEL CIRCULATION CENTER (LLCC). THIS LARGE FEEDER BAND IS
BEGINNING TO WRAP INTO THE LLCC. THE INITIAL POSITION IS BASED WITH
FAIR CONFIDENCE ON A NOTCH FEATURE IN THE 291800Z IRBD IMAGE WHICH
LINES UP VERY WELL WITH A LOW REFLECTIVITY CIRCULATION FEATURE IN THE
291633Z MICROWAVE PASS. THE INITIAL INTENSITY OF 50 KNOTS IS BASED ON
DVORAK INTENSITY ESTIMATES RANGING OF T3.0 AND T3.5 FROM PGTW AND
RJTD, RESPECTIVELY. ALSO, THE 291145Z ASCAT IMAGERY SUGGESTS A LARGER
WIND RADII TO THE SOUTHWEST OF THE LLCC. ENVIRONMENTAL ANALYSIS
SHOWS THAT TS 17W IS IN AN AREA OF LOW TO MODERATE (10-15 KNOT)
VERTICAL WIND SHEAR (VWS). SEA SURFACE TEMPERATURES (SST) AT 30
CELSIUS ARE CONDUCIVE FOR FURTHER DEVELOPMENT. TS 17W IS TRACKING
ALONG THE WESTERN EDGE OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO
THE NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 17W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD ALONG THE
SOUTHWESTERN EXTENT OF THE STR AS THE STR BUILDS. AFTER TAU 24, TS
17W WILL BEGIN TO SLOW AND TRACK NORTHEASTWARD AS IT ROUNDS THE
WESTERN EDGE OF THE STR. AT THIS TIME THE CYCLONE WILL BE IN A
FAVORABLE ENVIRONMENT AND EXPECT THE INTENSITY TO CONTINUE TO
INCREASE AND AT TAU 72 WILL PEAK AT 80 KNOTS. MODEL GUIDANCE REMAINS
IN GOOD AGREEMENT WITH A NORTHWESTWARD AND THEN NORTHEASTWARD TRACK
WITH JENS AND JGSM ON THE LEFT MARGIN OF THE MODEL ENVELOPE. THE JTWC
TRACK FORECAST IS LAID JUST TO THE RIGHT OF CONW TO OFFSET THESE
OUTLIERS.
C. AFTER TAU 72, TS SANVU WILL SIGNIFICANTLY ACCELERATE
NORTHEASTWARD AS IT GETS EMBEDDED IN THE PREVAILING WESTERLIES. AFTER
TAU 96, IT WILL BEGIN EXTRA TROPICAL TRANSITION (ETT) AND WILL
GRADUALLY ERODE MAINLY DUE TO INCREASING VWS. BY TAU 120, TS 17W WILL
COMPLETE ETT AND BECOME A STRONG GALE-FORCE COLD CORE LOW. MODEL
GUIDANCE CONTINUES TO BE IN GOOD AGREEMENT WITH AN ACCELERATING
NORTHEASTWARD TRAJECTORY. THE JTWC TRACK FORECAST IS LAID WITH HIGH
CONFIDENCE SLIGHTLY ON THE RIGHT AND FASTER THAN CONW.//
NNNN

[euro6208]

[euro6208]

That monsoon tail is quite astonishing.

[Macrocane]

Wow that monsoon trough

[euro6208]

WDPN31 PGTW 300300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (SANVU) WARNING NR
07//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 17W (SANVU), LOCATED APPROXIMATELY 129 NM EAST OF
CHICHI JIMA, JAPAN, HAS TRACKED NORTHWESTWARD AT 17 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS
THE LARGE CONVECTIVE BANDING HAS WRAPPED TIGHTER INTO A BROAD,
WELL-DEFINED, ALBEIT PARTLY EXPOSED LOW LEVEL CIRCULATION (LLC). THE
FEEDER BAND REMAINS EXTENSIVE AND TRAILS THE LLC BY OVER 900NM. THE
INITIAL POSITION IS BASED WITH FAIR CONFIDENCE ON THE MSI LOOP. THE
INITIAL INTENSITY OF 55 KNOTS IS BASED ON CONGRUENT DVORAK ESTIMATES
OF T3.5 FROM PGTW AND RJTD. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM
IS IN AN AREA OF LOW TO MODERATE (10-15 KNOT) VERTICAL WIND SHEAR
(VWS) AND EXCELLENT DUAL OUTFLOW. ADDITIONALLY, SEA SURFACE
TEMPERATURES (SST) AT 30 CELSIUS ARE CONDUCIVE FOR FURTHER
DEVELOPMENT. TS 17W IS TRACKING ALONG THE SOUTHWESTERN EDGE OF THE
DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 17W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD ALONG THE
SOUTHWESTERN EXTENT OF THE STR AS THE STR BUILDS. AFTER TAU 12, IT
WILL BEGIN TO SLOW AND TRACK NORTH THEN NORTHEASTWARD AS IT ROUNDS THE
WESTERN EDGE OF THE STR. THE CYCLONE WILL REMAIN IN A FAVORABLE
ENVIRONMENT WITH INCREASED POLEWARD OUTFLOW INTENSIFYING THE SYSTEM
TO A PEAK OF 80 KNOTS BY TAU 72. MODEL GUIDANCE REMAINS IN FAIRLY
TIGHT AGREEMENT WITH JENS AND JGSM ON THE LEFT MARGIN OF THE MODEL
ENVELOPE. THE JTWC TRACK FORECAST IS LAID JUST TO THE RIGHT OF CONW
TO OFFSET THESE OUTLIERS.
C. AFTER TAU 72, TS SANVU WILL SIGNIFICANTLY ACCELERATE
NORTHEASTWARD AS IT GETS EMBEDDED IN THE PREVAILING WESTERLIES.
CONCURRENTLY, IT WILL BEGIN EXTRA TROPICAL TRANSITION (ETT) AND WILL
GRADUALLY ERODE MAINLY DUE TO INCREASING VWS. BY TAU 96, TS 17W WILL
COMPLETE ETT AND BECOME A STRONG GALE-FORCE COLD CORE LOW. MODEL
GUIDANCE CONTINUES TO BE IN GOOD AGREEMENT. THIS PORTION OF THE JTWC
TRACK FORECAST IS LAID WITH HIGH CONFIDENCE SLIGHTLY TO THE RIGHT AND
FASTER THAN CONW.//
NNNN

[euro6208]

That is quite a low pressure recorded typical in monsoon systems.

WDPN31 PGTW 300900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (SANVU) WARNING NR
08//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 17W (SANVU), LOCATED APPROXIMATELY 37 NM EAST
OF CHICHI JIMA, HAS TRACKED WEST-NORTHWESTWARD AT 16 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
DEPICTS A BROAD, PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION CENTER WITH
MULTIPLE MESOVORTICES ROTATING CYCLONICALLY ABOUT A CENTROID. MSI
SHOWS DEEP CONVECTION PRIMARILY OVER THE NORTHERN SEMI-CIRCLE DUE TO
THE PRESENCE OF AN UPPER-LOW TO THE SOUTH AND CONVERGENT FLOW OVER
THE SOUTHERN SEMI-CIRCLE. A 300549Z NOAA-19 89GHZ COLOR COMPOSITE
IMAGE INDICATES TIGHTLY-CURVED SHALLOW BANDING WRAPPING INTO A
BROAD, DEFINED CENTER WITH LIMITED DEEP CONVECTION OVER THE
NORTHWEST QUADRANT. MSI AND THIS NOAA-19 IMAGE SUPPORT THE INITIAL
POSITION WITH FAIR CONFIDENCE. SURFACE OBSERVATIONS FROM CHICHI-JIMA
SHOW NORTHEASTERLY SUSTAINED 10-MINUTE AVERAGE WINDS OF 32 KNOTS
(MAXIMUM OF 36 KNOTS AT 30/0400Z) WITH MINIMUM SLP THUS FAR AT
973.9MB. THE INITIAL INTENSITY REMAINS ASSESSED AT 55 KNOTS BASED ON
DVORAK CURRENT INTENSITY ESTIMATES OF 3.5 (55 KNOTS) FROM ALL
AGENCIES AND A 30/0547Z SATCON ESTIMATE OF 52 KNOTS. TS 17W IS
TRACKING UNDER THE STEERING INFLUENCE OF AN EXTENSION OF THE
SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS PROGNOSTIC REASONING MESSAGE. HOWEVER, THE INITIAL AND
FORECAST 34-KNOT WIND RADII HAVE BEEN INCREASED SIGNIFICANTLY.
B. THE STR IS FORECAST TO WEAKEN AS A MIDLATITUDE SHORTWAVE
TROUGH DEEPENS OVER CENTRAL JAPAN BY TAU 24. THEREFORE, AFTER A
BRIEF SLOW-DOWN, TS 17W WILL TURN SHARPLY POLEWARD AND WILL
ACCELERATE NORTH-NORTHEASTWARD. THE SYSTEM IS FORECAST TO BEGIN
EXTRA-TROPICAL TRANSITION BY TAU 72 AS IT BEGINS TO INTERACT WITH
THE BAROCLINIC ZONE AND SHORTWAVE TROUGH. DYNAMIC MODEL GUIDANCE IS
IN GOOD AGREEMENT THROUGH TAU 72 WITH A SPREAD IN SOLUTIONS AT TAU
72 OF 160NM.
C. AFTER TAU 72, TS SANVU WILL SIGNIFICANTLY ACCELERATE
NORTH-NORTHEASTWARD AS IT BECOMES EMBEDDED WITHIN THE LEADING EDGE
OF THE MAJOR SHORTWAVE TROUGH AND RAPIDLY GAINS FRONTAL
CHARACTERISTICS. THE SYSTEM IS FORECAST TO COMPLETE EXTRA-TROPICAL
TRANSITION BY TAU 96 BUT IS EXPECTED TO REMAIN A STRONG COLD-CORE
LOW WITH EXPANSIVE GALE-FORCE WINDS. DYNAMIC MODEL GUIDANCE REMAINS
IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC
FORECAST TRACK.//
NNNN

[euro6208]

The models keep insisting this will strengthen very significantly.