WPAC: 01W - Post-Tropical

[cycloneye]

12Z JMA update:

LOW PRESSURE AREA 1006 HPA NEAR 06N 144E WEST SLOWLY.

[TyphoonNara]

TPPN10 PGTW 180506
A. TROPICAL DEPRESSION 01W (SW OF KWAJALEIN)
B. 18/0430Z
C. 6.56N
D. 138.36E
E. THREE/HMWRI8
F. N/A
G. IR/EIR/VIS/MSI
H. REMARKS: 19A/PBO XPSD LLCC/ANMTN.
I. ADDITIONAL POSITIONS: NONE
MARTIN

[TyphoonNara]

T1.0

TPPN10 PGTW 180900

A. TROPICAL DEPRESSION 01W (E OF PALAU)

B. 18/0830Z

C. 6.56N

D. 138.31E

E. THREE/HMWRI8

F. T1.0/1.0

G. IR/EIR

H. REMARKS: 17A/PBO XPSD LLCC/ANMTN. CNVCTN WRAPS .20 ON LOG10
SPIRAL YIELDING A DT OF 1.0. MET/PT AGREE. DBO DT.

I. ADDITIONAL POSITIONS: NONE


MARTIN

[TyphoonNara]

After many days, JTWC issued a TCFA again

1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 6.2N 139.8E TO 8.1N 128.0E
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 20 TO 25 KNOTS. METSAT
IMAGERY AT 180630Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 6.5N 138.3E. THE SYSTEM IS MOVING WESTWARD AT 06 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 01W) PREVIOUSLY LOCATED
NEAR 6.6N 138.3E, IS NOW LOCATED NEAR 6.5N 138.3E, APPROXIMATELY 229
NM EAST OF PALAU. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS
LOW LEVEL CLOUD LINES WRAPPING TIGHTLY INTO A WELL DEFINED LOW LEVEL
CIRCULATON CENTER (LLCC) WITH FLARING CONVECTION IN THE WESTERN
QUADRANT. A 180206Z GMI 89GHZ MICROWAVE IMAGE SHOWS SHALLOW BANDING
WRAPPING INTO A RAGGED LLCC. A 180033Z ASCAT PASS SHOWS NUMEROUS 15-
20 KNOT WINDS WITH ISOLATED 20-25 KNOT WINDS ON THE PERIPHERY. THE
UPPER LEVEL ENVIRONMENT IS MARGINALLY FAVORABLE WITH LOW TO MODERATE
(15-20KT) VWS AND STRONG DIVERGENCE. SEA SURFACE TEMPERATURES REMAIN
FAVORABLE (28-30C). GLOBAL MODELS ARE IN AGREEMENT WITH A CONTINUED
WESTWARD TRACK AND GRADUAL DEVELOPMENT PRIOR TO LANDFALL OVER
MINDANAO. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1003 MB.
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS HIGH.

[TyphoonNara]

TCFA Graphics

[TyphoonNara]

[euro6208]

000
WWPQ80 PGUM 180729
SPSPQ

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TIYAN GU
529 PM ChST Fri Jan 18 2019

PMZ161-171-190100-
KOROR PALAU-YAP-
529 PM ChST Fri Jan 18 2019

...TROPICAL CYCLONE FORMATION ALERT ISSUED ON DISTURBANCE NEAR YAP...

THE CIRCULATION SOUTH OF YAP IS NOW THE SUBJECT OF A TROPICAL CYCLONE
FORMATION ALERT BY THE JOINT TYPHOON WARNING CENTER. IT CONTINUES TO
DRIFT WESTWARD WITH MAXIMUM WINDS OF 25 KT. IT IS CURRENTLY NEAR
6.5N138E...OR ABOUT 210 MILES SOUTH OF YAP AND 275 MILES EAST-
SOUTHEAST OF KOROR.

HEAVY SHOWERS...ISOLATED THUNDERSTORMS AND GUSTY WINDS ARE FOUND TO
THE WEST AND NORTH OF THE CENTER...INCLUDING OVER MUCH OF PALAU AND
YAP. SLOW DEVELOPMENT IS EXPECTED THE NEXT COUPLE OF DAYS AS IT
PASSES NEAR AND WEST OF KOROR SATURDAY.

SCATTERED TO NUMEROUS SHOWERS...ISOLATED THUNDERSTORMS AND GUSTY
NORTH TO EAST WINDS OF 20 TO 30 KT WILL PERSIST OVER YAP AND KOROR
TONIGHT. NORTHWEST TO WEST WINDS ARE EXPECTED AT SOME OF THE
SOUTHERN ISLANDS OF PALAU. HAZARDOUS MARINE CONDITIONS AND SURF WILL
PERSIST THE NEXT COUPLE OF DAYS.

RESIDENTS OF THE REPUBLIC OF PALAU AND YAP STATE SHOULD MONITOR
WEATHER CONDITIONS AND HEED THE INSTRUCTIONS FROM LOCAL EMERGENCY
MANAGEMENT AND WEATHER SERVICE OFFICES. MORE INFORMATION ON THE TCFA
CAN BE FOUND UNDER BULLETINS ISSUED BY THE JTWC UNDER WMO HEADER
WTPN21 PGTW. THE LATEST WEATHER FORECASTS ARE AVAILABLE ON THE WFO
GUAM WEBSITE AT WWW.WEATHER.GOV/GUM/

$$

AYDLETT

[TyphoonNara]

JMA upgraded the system into a tropical depression

TROPICAL DEPRESSION 1004 HPA AT 07N 132E WNW 10 KT.

[TyphoonNara]

JTWC downgraded the system to Medium, albeit JMA's upgrade

THE AREA OF CONVECTION (RMNTS 01W) PREVIOUSLY LOCATED NEAR
6.5N 138.3E, IS NOW LOCATED NEAR 6.6N 132.1E, APPROXIMATELY 390 NM
EAST OF DAVAO CITY, PHILIPPINES. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY AND A 190011Z PARTIAL ASCAT PASS DEPICT A PARTIALLY EXPOSED,
ELONGATED LOW LEVEL CIRCULATION WITH CONVECTION DISPLACED TO THE
WEST. VERTICAL WIND SHEAR IS CURRENTLY MODERATE (10-20KTS) AND
INCREASES AHEAD OF THE SYSTEM. GLOBAL MODELS PREDICT THAT THE SYSTEM
WILL LIKELY NOT CONSOLIDATE INTO A TROPICAL DEPRESSION, INSTEAD
REMAINING A LOOSE LOW LEVEL CIRCULATION DRIVEN BY NORTHEASTERLY
GRADIENT FLOW. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15
TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1007
MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL
CYCLONE WITHIN THE NEXT 24 HOURS IS DOWNGRADED TO MEDIUM.

[euro6208]

TPPN10 PGTW 190859

A. REMNANTS OF TROPICAL DEPRESSION 01W (W OF PALAU)

B. 19/0830Z

C. XX.XX

D. XXX.XX

E. N/A/HMWRI8

F. N/A

G. IR/EIR/VIS/MSI

H. REMARKS: POSITION OF LOW LEVEL CIRCULATION CENTER COULD NOT
BE FOUND.

I. ADDITIONAL POSITIONS: NONE


MILAM

[euro6208]

GLOBAL MODELS PREDICT THAT THE SYSTEM
WILL LIKELY NOT CONSOLIDATE INTO A TROPICAL DEPRESSION, INSTEAD
REMAINING A LOOSE LOW LEVEL CIRCULATION DRIVEN BY NORTHEASTERLY
GRADIENT FLOW.

[TyphoonNara]

PAGASA named the system "Amang"

Tropical Depression"Amang"
Tropical Cyclone: WARNING
Issued at 11:00 pm, 19 January 2019
(Valid for broadcast until the next bulletin to be issued at 2:00 am tomorrow.)

THE LOW PRESSURE AREA (LPA) EAST OF HINATUAN, SURIGAO DEL SUR HAS DEVELOPED INTO A TROPICAL DEPRESSION AND WAS NAMED "AMANG".
Possible raising of Tropical Cyclone Warning Signal #1 (TCWS #1) over Eastern Bohol and Southern Leyte in the next Severe Weather Bulletin. Possible disruption of maritime travel is expected over these areas.
TD "AMANG" is expected to landfall over Surigao del Norte mainland-Siargao Islands between tomorrow afternoon and evening (20 January).
Moderate to heavy rains will prevail over Caraga, Davao Oriental, Compostela Valley, Camiguin, and Misamis Oriental beginning today (19 January). Meanwhile, tomorrow (20 January), moderate to heavy rains may prevail over Caraga, Northern Mindanao, Eastern Visayas, Central Visayas, Bicol Region, Southern Quezon, Marinduque and Romblon. On Monday (21 January), moderate to heavy rains may be experienced over Visayas, Bicol Region, Southern Quezon, Marinduque, and Romblon. Residents in these areas, especially those living in areas at high to very high risk of flooding and landslides are advised to take precautionary measures.
Fisherfolks and those with small seacrafts are advised not to venture out over the seaboards of areas under TCWS #1, the northern seaboard of Northern Luzon, eastern seaboards of Northern, Central and Southern Luzon, and eastern seaboards of Visayas and Mindanao due to the approaching Tropical Depression and the surge of Northeast Monsoon.

[euro6208]

[euro6208]

THE AREA OF CONVECTION (RMNTS 01W) PREVIOUSLY LOCATED NEAR
6.6N 132.1E, IS NOW LOCATED NEAR 8.3N 128.3E, APPROXIMATELY 175 NM
EAST-NORTHEAST OF DAVAO CITY, PHILIPPINES. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY AND A 190156Z 89GHZ GMI MICROWAVE IMAGE DEPICT
FLARING, DISORGANIZED CONVECTION WITH SOME MIDLEVEL TURNING ABOVE AN
OBSCURED, ELONGATED LOW LEVEL CIRCULATION. THE UPPER LEVEL
ENVIRONMENT IS OVERALL FAVORABLE, WITH NEARLY DUAL CHANNEL OUTFLOW
SLIGHTLY OFFSET BY SOME SOUTHEASTERLY INFLOW. VERTICAL WIND SHEAR IS
CURRENTLY LOW (10-15KTS) BUT QUICKLY BECOMES UNFAVORABLE AHEAD OF
THE SYSTEM. SEA SURFACE TEMPERATURES REMAIN FAVORABLE (26-28C) IN
THIS PORTION OF THE PHILIPPINE SEA. GLOBAL MODELS AGREE ON A
SCENARIO WITH RMNTS 01W LIKELY DISSIPATING BETWEEN TAU 24-48 AFTER
INTERACTING WITH THE PHILIPPINE ISLANDS AND COLD NORTHEASTERLY FLOW.
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]

THE AREA OF CONVECTION (RMNTS 01W) PREVIOUSLY LOCATED NEAR
8.3N 128.3E, IS NOW LOCATED NEAR 11.9N 125.4E, APPROXIMATELY 305 NM
EAST-SOUTHEAST OF MANILA, PHILIPPINES. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY AND A 210110Z PARTIAL ASCAT PASS DEPICT AN
ELONGATED, PARTIALLY EXPOSED LOW LEVEL CIRCULATION (LLC) WITH SOME
WEAKENING DEEP CONVECTION SHEARED NORTHWEST OF THE LLC. THE
AFOREMENTIONED ASCAT PASS ALSO SHOWS A SWATH OF 15-20 KNOT WINDS
FLOWING IN FROM THE NORTHEAST. VERTICAL WIND SHEAR IS LOW (10-15KTS)
OVER THE LLC BUT INCREASES SHARPLY TO THE NORTH AND WEST. UPPER
LEVEL OUTFLOW IS VERY STRONG AS 01W HAS MOVED DIRECTLY BELOW THE
AXIS OF AN UPPER LEVEL RIDGE, FORMING A WELL DEFINED POLEWARD
OUTFLOW CHANNEL. SEA SURFACE TEMPERATURES REMAIN FAVORABLE (26-28C)
ALONG THE EDGE OF THE PHILIPPINE ISLANDS. GLOBAL MODELS ARE STILL
PREDICTING DISSIPATION OVER THE NEXT 24-48HRS AS 01W INTERACTS WITH
THE PHILIPPINE ISLANDS AND COLDER NORTHEASTERLY SURFACE FLOW,
DESPITE AN UNANTICIPATED TURN NORTH OVER THE PREVIOUS 24 HOURS.
CONVECTION IS BEING SUSTAINED BY THE PREVIOUSLY MENTIONED
NORTHEASTERLY GRADIENT FLOW AND STRONG POLEWARD OUTFLOW. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE POTENTIAL FOR
THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS REMAINS MEDIUM.

[Hayabusa]

JMA loves this storm
TD
Issued at 13:05 UTC, 21 January 2019

<Analysis at 12 UTC, 21 January>
Scale -
Intensity -
TD
Center position N12°50' (12.8°)
E126°00' (126.0°)
Direction and speed of movement N 10 km/h (6 kt)
Central pressure 1004 hPa
Maximum wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)

<Forecast for 12 UTC, 22 January>
Intensity -
Center position of probability circle N14°35' (14.6°)
E124°25' (124.4°)
Direction and speed of movement NW 10 km/h (6 kt)
Central pressure 1002 hPa
Maximum wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 200 km (110 NM)

[1900hurricane]

I'd actually give it a nod for classification now.

[TyphoonNara]

Meanwhile, JTWC keeps the system at medium

THE AREA OF CONVECTION (RMNTS 01W) PREVIOUSLY LOCATED NEAR
8.3N 128.3E, IS NOW LOCATED NEAR 11.9N 125.4E, APPROXIMATELY 305 NM
EAST-SOUTHEAST OF MANILA, PHILIPPINES. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY AND A 210110Z PARTIAL ASCAT PASS DEPICT AN
ELONGATED, PARTIALLY EXPOSED LOW LEVEL CIRCULATION (LLC) WITH SOME
WEAKENING DEEP CONVECTION SHEARED NORTHWEST OF THE LLC. THE
AFOREMENTIONED ASCAT PASS ALSO SHOWS A SWATH OF 15-20 KNOT WINDS
FLOWING IN FROM THE NORTHEAST. VERTICAL WIND SHEAR IS LOW (10-15KTS)
OVER THE LLC BUT INCREASES SHARPLY TO THE NORTH AND WEST. UPPER
LEVEL OUTFLOW IS VERY STRONG AS 01W HAS MOVED DIRECTLY BELOW THE
AXIS OF AN UPPER LEVEL RIDGE, FORMING A WELL DEFINED POLEWARD
OUTFLOW CHANNEL. SEA SURFACE TEMPERATURES REMAIN FAVORABLE (26-28C)
ALONG THE EDGE OF THE PHILIPPINE ISLANDS. GLOBAL MODELS ARE STILL
PREDICTING DISSIPATION OVER THE NEXT 24-48HRS AS 01W INTERACTS WITH
THE PHILIPPINE ISLANDS AND COLDER NORTHEASTERLY SURFACE FLOW,
DESPITE AN UNANTICIPATED TURN NORTH OVER THE PREVIOUS 24 HOURS.
CONVECTION IS BEING SUSTAINED BY THE PREVIOUSLY MENTIONED
NORTHEASTERLY GRADIENT FLOW AND STRONG POLEWARD OUTFLOW. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE POTENTIAL FOR
THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS REMAINS MEDIUM.

[TyphoonNara]

Despite being more organised than a few days before, JTWC is not upgrading the system.

For some reason JTWC is performing poorly recently.

[senorpepr]

Despite being more organised than a few days before, JTWC is not upgrading the system.

For some reason JTWC is performing poorly recently.

Why do you suggest JTWC is performing poorly recently? I felt their rationale for not upgrading is very sound. JMA tends to have a looser definition of the term tropical depression, but it's a little surprising PAGASA upgrading the system. The disturbance never had Dvorak analysis above T1.0. The JTWC checklist supported issuing the TCFA due to the proximity of land, but the system was just too weak... and has been for the past week or so... not to minimize the rain threat that the Philippines is dealing with.