WPAC: CHOI-WAN - Severe Tropical Storm

[Extratropical94]

99W INVEST 150927 0000 9.5N 175.0E WPAC 15 NA

A new invest has formed near the dateline.

[euro6208]

.EASTERN MICRONESIA...
ASCAT ANALYSIS SHOWS A MONSOON TROUGH EXTENDS ALONG 8N-10N TO THE
NORTH OF POHNPEI...KOSRAE AND MAJURO THROUGH A TROPICAL DISTURBANCE
CENTERED NORTHEAST OF MAJURO AT ABOUT 9N175E. SCATTERED SHOWERS AND
A FEW THUNDERSTORMS ARE OVERSPREADING THE MARSHALL ISLANDS THIS
AFTERNOON. MOST MODELS INDICATE THE DISTURBANCE WILL MOVE NORTHWEST
AND FURTHER DEVELOP DURING THE NEXT FEW DAYS. IT WILL BE SLOW
MOVING AND LIKELY TRIGGER ISOLATED THUNDERSTORMS AT KOSRAE BY
TUESDAY THROUGH FRIDAY AND POHNPEI MAINLY ON TUESDAY. MAJURO
WEATHER SHOULD START IMPROVING BY THURSDAY.

[euro6208]

Looking at the latest but old EURO run, it is likely that this is the area that develops into a big monsoon circulation that spawns twins.

[euro6208]

Majority of the models making this a big typhoon.

JMA



NAVGEM



CMC



EURO...Starting to see hints of another developing system near the dateline...

[euro6208]

18Z GFS with a pair of typhoons developing and one of them crosses over the CPAC and again goes back to the WPAC.

[euro6208]

NAVGEM develops this into Mujigae in 78 hours and peaks it at 927 mb in 180 hours. Looks like the far islands of the CNMI will feel the brunt of this monster.

CMC like always develop this into a monster, peaks it at 947 mb but further south than NAVGEM taking it straight to the northern islands of the CNMI.

EURO has Mujigae as a TS in just 120 hours, TY in 168 hours, and peaks it at 961 mb long range with no threat to land. Thankfully.

[euro6208]

Looking very interesting...

[euro6208]

EURO develops this into a very large powerful monster.

It has a typhoon in just 120 hours, 48 hours earlier than the past run.

Bottoms it out at 893 mb!

[1900hurricane]

Waters in the vicinity of this invest are some of the warmest and deepest the Pacific has to offer. Provided the right atmospheric conditions, a very high intensity storm can develop and be sustained here.

[euro6208]

Upgraded to LOW

AN AREA OF CONVECTION HAS PERSISTED NEAR 13.5N 171.0E,
APPROXIMATELY 425 NM SOUTHEAST OF WAKE ISLAND. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY DEPICTS AN ELONGATED LOW LEVEL
CIRCULATION CENTER (LLCC) EMBEDDED WITHIN THE MONSOON TROUGH WITH
WELL-DEFINED MID-LEVEL CYCLONIC TURNING. A 282233Z ASCAT PASS
FURTHER ILLUSTRATED THE ILL-DEFINED NATURE OF THE LLCC; HOWEVER, THE
AREA IS BEING ENHANCED BY A 15 TO 20 KNOT WESTERLY SURGE NEAR 8
DEGREES LATITUDE. THERE IS A FAVORABLE UPPER LEVEL ENVIRONMENT WITH
THE DISTURBANCE UNDER AN UPPER-LEVEL ANTI-CYCLONE PROVIDING VIGOROUS
OUTFLOW AND LOW VERTICAL WIND SHEAR. GLOBAL MODELS SHOW FURTHER
DEVELOPMENT OF THIS DISTURBANCE IN THE NEXT FEW DAYS. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR
THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS LOW.

[1900hurricane]

JTWC has now given this a medium.

[euro6208]

Remains MEDIUM

THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 15.3N
168.4E, IS NOW LOCATED NEAR 14.6N 168.4E, APPROXIMATELY 290 NM SOUTH-
SOUTHEAST OF WAKE ISLAND. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS AN EXPANSIVE LOW-LEVEL CIRCULATION CENTER (LLCC) WITH CURVED
DEEP CONVECTIVE BANDING PERSISTING OVER THE WESTERN AND EASTERN
PERIPHERIES OF THE LLCC. A 300101Z AMSR-2 89 GHZ MICROWAVE IMAGE
SHOWED MOSTLY DISORGANIZED CONVECTION ASSOCIATED WITH AN ELONGATED
LLCC. THERE IS A FAVORABLE UPPER-LEVEL ENVIRONMENT WITH NEAR RADIAL
OUTFLOW AND LOW VERTICAL WIND SHEAR. GLOBAL MODELS SHOW FURTHER
DEVELOPMENT OF THIS DISTURBANCE IN THE NEXT TWO DAYS. 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 REMAINS MEDIUM.

[euro6208]

Remains MEDIUM...

THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 14.6N
168.4E, IS NOW LOCATED NEAR 16.1N 166.7E, APPROXIMATELY 190 NM SOUTH
OF WAKE ISLAND. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A VERY
EXPANSIVE SYSTEM WITH A BROAD LOW-LEVEL CIRCULATION WITH FRAGMENTED,
ALBEIT FORMATIVE, CONVECTIVE BANDING PERSISTING OVER THE WESTERN AND
EASTERN PERIPHERIES. UPPER LEVEL ANALYSIS INDICATES A FAVORABLE
UPPER-LEVEL ENVIRONMENT WITH NEAR RADIAL OUTFLOW AND LOW VERTICAL
WIND SHEAR. ADDITIONALLY, SEA SURFACE TEMPERATURE AT 29 CELSIUS, IS
HIGHLY CONDUCIVE FOR DEVELOPMENT. GLOBAL MODELS SHOW FURTHER
DEVELOPMENT OF THIS SYSTEM OVER THE NEXT TWO DAYS. 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 REMAINS MEDIUM.

[euro6208]

JMA still very impressive bottoms this to 967 mb as it recurves...

NAVGEM also recurves bottoms at 957 mb.

EURO also recurves and peaks it at 953 mb as it lands over Tokyo.

[euro6208]

It's large massive circulation has somewhat slowed it's development and will continue to do so that's why all models are trending weaker.

[Extratropical94]

TD, expected TS by JMA.

TROPICAL DEPRESSION 1004 HPA
AT 18.1N 167.4E WAKE MOVING WEST SLOWLY.
POSITION POOR.
MAX WINDS 30 KNOTS.
EXPECTED MAX WINDS 35 KNOTS FOR NEXT 24 HOURS.

TD
Issued at 13:30 UTC, 1 October 2015
<Analyses at 01/12 UTC>
Scale -
Intensity -
TD
Center position N18°05'(18.1°)
E167°25'(167.4°)
Direction and speed of movement W Slowly
Central pressure 1004hPa
Maximum sustained wind speed 15m/s(30kt)
Maximum wind gust speed 23m/s(45kt)
<Forecast for 02/12 UTC>
Intensity -
Center position of probability circle N18°10'(18.2°)
E165°50'(165.8°)
Direction and speed of movement W Slowly
Central pressure 996hPa
Maximum sustained wind speed 18m/s(35kt)
Maximum wind gust speed 25m/s(50kt)
Radius of probability circle 220km(120NM)

[euro6208]

Remains MEDIUM

THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 16.1N
166.7E, IS NOW LOCATED NEAR 19.1N 166.8E, APPROXIMATELY 12 NM
SOUTHEAST OF WAKE ISLAND. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
SHOWS A VERY EXPANSIVE SYSTEM WITH A BROAD LOW-LEVEL CIRCULATION
WITH FORMATIVE CONVECTIVE BANDS SLOWLY CONSOLIDATING TOWARDS A
CENTROID. THE CENTROID IS SURROUNDED BY AT LEAST TWO WEAK ORBITING
VORTICES. UPPER LEVEL ANALYSIS INDICATES A FAVORABLE UPPER-LEVEL
ENVIRONMENT WITH NEAR RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR.
ADDITIONALLY, SEA SURFACE TEMPERATURE AT 29 CELSIUS, IS HIGHLY
CONDUCIVE FOR DEVELOPMENT. GLOBAL MODELS SHOW FURTHER CONSOLIDATION
AND DEVELOPMENT OF THIS SYSTEM OVER THE NEXT TWO DAYS. 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 MEDIUM.

[euro6208]

WTPN21 PGTW 020830
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
235 NM EITHER SIDE OF A LINE FROM 18.0N 167.3E TO 21.4N 160.5E
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 18 TO 23 KNOTS. METSAT
IMAGERY AT 020600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 19.0N 166.9E. THE SYSTEM IS MOVING NORTH-NORTHWESTWARD AT 04
KNOTS.
2. REMARKS:
THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 19.1N 166.8E, IS
NOW LOCATED NEAR 19.0N 166.9E, APPROXIMATELY 22 NM SOUTHEAST OF WAKE
ISLAND. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A VERY
EXPANSIVE SYSTEM WITH A BROAD LOW-LEVEL CIRCULATION WITH FORMATIVE
CONVECTIVE BANDS SLOWLY CONSOLIDATING TOWARDS A CENTROID. THE
CENTROID IS VOID OF ANY DEEP CONVECTION WITHIN 50 NM ON ALL
QUADRANTS; HOWEVER IT IS SURROUNDED BY AT LEAST TWO WEAK ORBITING
VORTICES WITH EXPANSIVE AND DEEP CONVECTION ESPECIALLY TO THE
NORTHEAST. UPPER LEVEL ANALYSIS INDICATES A FAVORABLE UPPER-LEVEL
ENVIRONMENT WITH NEAR RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR.
ADDITIONALLY, SEA SURFACE TEMPERATURE AT 29 CELSIUS, IS HIGHLY
CONDUCIVE FOR DEVELOPMENT. GLOBAL MODELS SHOW FURTHER CONSOLIDATION
AND DEVELOPMENT OF THIS SYSTEM OVER THE NEXT TWO DAYS. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 998 MB. 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
030830Z.
NNNN

[Extratropical94]

Now a tropical storm.

TS 1523 (CHOI-WAN)
Issued at 10:00 UTC, 2 October 2015

<Analyses at 02/09 UTC>
Scale Large
Intensity -
Center position N18°50'(18.8°)
E166°35'(166.6°)
Direction and speed of movement NW Slowly
Central pressure 996hPa
Maximum sustained wind speed 18m/s(35kt)
Maximum wind gust speed 25m/s(50kt)
Area of 30kt winds or more ALL750km(400NM)

<Forecast for 03/09 UTC>
Intensity -
Center position of probability circle N19°00'(19.0°)
E163°25'(163.4°)
Direction and speed of movement W 15km/h(8kt)
Central pressure 990hPa
Maximum sustained wind speed 23m/s(45kt)
Maximum wind gust speed 35m/s(65kt)
Radius of probability circle 130km(70NM)

<Forecast for 04/06 UTC>
Intensity -
Center position of probability circle N20°20'(20.3°)
E158°25'(158.4°)
Direction and speed of movement WNW 25km/h(13kt)
Central pressure 985hPa
Maximum wind speed near the center 25m/s(50kt)
Maximum wind gust speed 35m/s(70kt)
Radius of probability circle 260km(140NM)

<Forecast for 05/06 UTC>
Intensity -
Center position of probability circle N21°50'(21.8°)
E153°10'(153.2°)
Direction and speed of movement WNW 25km/h(13kt)
Central pressure 975hPa
Maximum wind speed near the center 30m/s(60kt)
Maximum wind gust speed 45m/s(85kt)
Radius of probability circle 390km(210NM)
Storm warning area ALL500km(270NM)

[Extratropical94]

23W TWENTYTHREE 151002 0600 19.0N 166.9E WPAC 20 1007