WPAC: NANGKA - Post-Tropical

[Hayabusa]

93W.INVEST

[Hayabusa]

[mrbagyo]

93W INVEST 201011 0000 17.1N 120.0E WPAC 15 1010

[Ed_2001]

Latest GFS deepens it to a minimal typhoon, landfall on Hainan Island in 3 days

[Hayabusa]

ABPW10 PGTW 110600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
/SOUTH PACIFIC OCEANS/110600Z-120600ZOCT2020//
B. TROPICAL DISTURBANCE SUMMARY:
(1) AN AREA OF CONVECTION (INVEST 93W) HAS PERSISTED NEAR
16.9N 119.2E, APPROXIMATELY 166 NM NORTH-NORTHWEST OF MANILLA,
PHILIPPINES. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND AN
110202Z METOP-B 89GHZ MICROWAVE IMAGE REVEAL SHALLOW FRAGMENTED
FORMATIVE BANDING WRAPPING INTO A LOW LEVEL CIRCULATION WITH LIMITED
DEEP CONVECTION. AN 110204Z ASCAT-B PASS REVEALS MAINLY 10-15KT
WINDS WITH SOME 20KT WINDS DISPLACED TO THE NORTH. INVEST 93W IS IN
A FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH LOW (<15KTS) VERTICAL
WIND SHEAR, MODERATE UPPER LEVEL DIFFLUENCE, AND WARM (29-30C) SEA
SURFACE TEMPERATURES. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT
INVEST 93W WILL CONTINUE TO CONSOLIDATE AND TRACK WEST-NORTHWESTWARD
ACROSS THE SOUTH CHINA SEA. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1002 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS MEDIUM.

[euro6208]

WTPN21 PGTW 110930
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 93W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
135 NM EITHER SIDE OF A LINE FROM 17.0N 119.4E TO 18.0N 114.9E
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 15 TO 20 KNOTS. METSAT
IMAGERY AT 110600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 17.0N 118.9E. THE SYSTEM IS MOVING WESTWARD AT 08 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 93W) PREVIOUSLY LOCATED
NEAR 16.9N 119.2E IS NOW LOCATED NEAR 17.0N 118.9E, APPROXIMATELY
183 NM NORTHWEST OF MANILA, PHILIPPINES. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY AND AN 110547Z AMSR2 89GHZ MICROWAVE IMAGE REVEAL
SHALLOW FRAGMENTED FORMATIVE BANDING WRAPPING INTO A LOW LEVEL
CIRCULATION WITH LIMITED DEEP CONVECTION. AN 110204Z ASCAT-B PASS
REVEALS MAINLY 10-15KT WINDS WITH SOME 20KT WINDS DISPLACED TO THE
NORTH. INVEST 93W IS IN A FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH
LOW (<15KTS) VERTICAL WIND SHEAR, MODERATE UPPER LEVEL DIFFLUENCE,
AND WARM (29-30C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE IN
STRONG AGREEMENT THAT INVEST 93W WILL QUICKLY CONSOLIDATE AND TRACK
WEST-NORTHWESTWARD ACROSS THE SOUTH CHINA SEA. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1001 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
120930Z.//
NNNN

[Hayabusa]

TD
Issued at 10:20 UTC, 11 October 2020

<Analysis at 09 UTC, 11 October>
Scale -
Intensity -
TD
Center position N16°55' (16.9°)
E119°10' (119.2°)
Direction and speed of movement W 10 km/h (6 kt)
Central pressure 1002 hPa
Maximum sustained wind speed 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)

[euro6208]

EURO has a weak TS making landfall over Hainan Island.

[euro6208]

In contrast, GFS brings a 981 mb typhoon onshore.

[Hayabusa]

Euro 6Z has now named this as 18W, so probably JTWC upgraded it.

[Ed_2001]

18W EIGHTEEN 201011 1800 17.4N 118.2E WPAC 25 1000

[Ed_2001]

60 knots

[ElectricStorm]

Pretty good chance this will become a Cat 1 before landfall

[euro6208]

WDPN33 PGTW 112100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 18W (EIGHTEEN)
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 18W (EIGHTEEN), LOCATED APPROXIMATELY 237
NM NORTHWEST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD
AT 07 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY REVEALS CONVECTIVE BANDING WRAPPING INTO A
LOW LEVEL CIRCULATION CENTER (LLCC) OBSCURED BY FLARING CONVECTION
OVERHEAD. AN 111759Z AMSR2 89 GHZ MICROWAVE IMAGE DEPICTS FRAGMENTED
CONVECTIVE BANDING NORTH OF A CONSOLIDATING LLCC, LENDING GOOD
CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY IS SET AT
25 KTS BASED ON MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF
T1.0-1.5 (25 KTS) BY PGTW, KNES, AND RJTD AND RECENT ASCAT DATA. TD
18W IS TRACKING THROUGH A FAVORABLE ENVIRONMENT CONSISTING OF GOOD
EQUATORWARD OUTFLOW, LOW (<10 KT) VERTICAL WIND SHEAR (VWS), AND HIGH
(29-30 CELSIUS) SEA SURFACE TEMPERATURES (SST). UNDER THE INFLUENCE
OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH, TD 18W IS
TRACKING GENERALLY WESTWARD ALONG ITS SOUTHERN PERIPHERY.
3. FORECAST REASONING.
A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE AND SETS THE
FORECAST PHILOSOPHY.
B. THE AFOREMENTIONED STR WILL ACT AS THE STEERING MECHANISM
THROUGHOUT THE ENTIRE FORECAST PERIOD. THROUGH TAU 48, TD 18W IS
FORECAST TO TRACK GENERALLY WESTWARD AS IT STEADILY STRENGTHENS TO A
PEAK INTENSITY OF 60 KTS BY TAU 36 DUE TO CONTINUED FAVORABLE
ENVIRONMENTAL CONDITIONS. AFTERWARDS, THE SYSTEM WILL SHIFT TO A
WEST-NORTHWESTWARD TRACK THROUGH TAU 72, MAINTAINING INTENSITY
THROUGH TAU 48 AND THEN GRADUALLY WEAKENING AS IT TRACKS OVER HAINAN
AND INTO THE GULF OF TONKIN. THROUGH TAU 72, NUMERICAL MODEL GUIDANCE
IS IN GOOD AGREEMENT WITH THE EXCEPTION OF NAVGEM WHICH PRESENTS A
SOUTHERLY OUTLIER. THERE IS ONLY 50 NM OF TRACK SPREAD AMONG THE
MAJORITY OF THE MODELS AT TAU 48, LENDING GOOD CONFIDENCE TO THE JTWC
NEAR-TERM FORECAST TRACK.
C. IN THE EXTENDED RANGE, TD 18W WILL TRACK GENERALLY WESTWARD
ALONG THE PERIPHERY OF THE AFOREMENTIONED STR AS IT MAKES LANDFALL IN
NORTHERN VIETNAM AFTER TAU 72. BY TAU 72, NUMERICAL MODEL SPREAD
INCREASES TO 100 NM, PLACING SOME UNCERTAINTY IN THE EXACT LOCATION
WHERE TD 18W WILL MAKE LANDFALL; CURRENT GUIDANCE DEPICTS LANDFALL
SOUTH OF HANOI, VIETNAM. AFTERWARDS, THE SYSTEM WILL STEADILY WEAKEN
DUE TO INTERACTION WITH THE RUGGED TERRAIN AND DISSIPATION OVER LAND
IS ANTICIPATED BY TAU 96. THE JTWC FORECAST TRACK LIES NEAR THE
MULTI-MODEL CONSENSUS; HOWEVER, DUE TO THE INCREASING MODEL SPREAD IN
THE EXTENDED RANGE, THERE IS OVERALL FAIR CONFIDENCE IN THE JTWC
FORECAST TRACK.//
NNNN

[Hayabusa]

TS 2016 (Nangka)
Issued at 07:00 UTC, 12 October 2020

<Analysis at 06 UTC, 12 October>
Scale -
Intensity -
Center position N17°35' (17.6°)
E115°40' (115.7°)
Direction and speed of movement W 20 km/h (10 kt)
Central pressure 998 hPa
Maximum sustained wind speed 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
≥ 30 kt wind area N 390 km (210 NM)
S 220 km (120 NM)

[Hayabusa]

I'm not saying it's weird but at 3Z JMA issued an emergency warning but what prompted it? It's not like 18W became a TS at 3Z and it's now ~830Z at the time of this post and 18W only got named at 6Z

WWJP28 RJTD 120300
EMERGENCY WARNING 120300.
WARNING VALID 130300.
STORM WARNING.
TROPICAL DEPRESSION 1000 HPA
AT 17.6N 116.6E SOUTH CHINA SEA MOVING WEST 08 KNOTS.
POSITION FAIR.
MAX WINDS 30 KNOTS.
EXPECTED MAX WINDS 50 KNOTS NEAR CENTER WITHIN NEXT 24 HOURS.
FORECAST POSITION FOR 121500UTC AT 18.1N 114.2E WITH 45 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.
FORECAST POSITION FOR 130300UTC AT 18.6N 111.9E WITH 60 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.

JAPAN METEOROLOGICAL AGENCY.=

[euro6208]

WDPN33 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (NANGKA)
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 18W (NANGKA), LOCATED APPROXIMATELY 277 NM
SOUTH-SOUTHEAST OF HONG KONG, HAS TRACKED WESTWARD AT 13 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS
A CONSOLIDATING SYSTEM WITH IMPROVED CONVECTIVE BANDING WRAPPING
INTO THE LOW-LEVEL CIRCULATION CENTER (LLCC). A 120826Z SSMIS 91GHZ
COLOR COMPOSITE IMAGE INDICATES FRAGMENTED CONVECTIVE BANDING
WRAPPING INTO THE LLCC. THE INITIAL INTENSITY IS ASSESSED AT 35
KNOTS, HEDGED ABOVE THE PGTW/RJTD DVORAK INTENSITY ESTIMATES OF T2.0
(30 KNOTS), BASED ON A 120519Z SATCON ESTIMATE OF 38 KNOTS AND A
120600Z ADT ESTIMATE OF 2.3/2.5 (35 KNOTS). UPPER-LEVEL ANALYSIS
REVEALS A FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND SHEAR, GOOD
EQUATORWARD OUTFLOW AND EXPANDING POLEWARD OUTFLOW. ADDITIONALLY,
SST (29-30C) VALUES ARE CONDUCIVE FOR FURTHER DEVELOPMENT. TS 18W IS
TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL
RIDGE (STR) POSITIONED TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. THE AFOREMENTIONED STR WILL ACT AS THE STEERING MECHANISM
THROUGHOUT THE ENTIRE FORECAST PERIOD. TS 18W IS FORECAST TO TRACK
GENERALLY WESTWARD THROUGH THE TAU 72 AS IT INTENSIFIES TO A PEAK
INTENSITY OF 60 KTS BY TAU 24. BY TAU 36, THE SYSTEM WILL WEAKEN AS
IT TRACKS GRADUALLY OVER HAINAN ISLAND AND INTO THE GULF OF TONKIN.
TS 18W WILL MAKE LANDFALL OVER NORTHEAST VIETNAM NEAR TAU 60 AND
WILL WEAKEN AS IT TRACKS INLAND. NUMERICAL MODEL GUIDANCE REMAINS IN
TIGHT AGREEMENT THROUGH TAU 72.
C. IN THE EXTENDED RANGE, TS 18W WILL TRACK FURTHER INLAND OVER
MOUNTAINOUS TERRAIN AND WILL DISSIPATE BY TAU 96. THE JTWC FORECAST
TRACK LIES NEAR THE MULTI-MODEL CONSENSUS WITH OVERALL HIGH
CONFIDENCE.//
NNNN

[euro6208]

WDPN33 PGTW 130900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (NANGKA)
WARNING NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 18W (NANGKA), LOCATED APPROXIMATELY 264 NM
SOUTHWEST OF HONG KONG, HAS TRACKED WESTWARD AT 07 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE DEPICTS A BROAD
SYSTEM WITH WELL DEFINED BANDING SPIRALING INTO A WELL DEFINED
CENTRAL LLCC. HOWEVER THE CONVECTIVE SIGNATURE IS SOMEWHAT
FRAGMENTED, WITH NO CENTRAL DEEP CONVECTION AND ONLY FRAGMENTED
AREAS OF CONVECTION WELL DISPLACED FROM THE LLCC. THE INITIAL
POSITION IS PLACED WITH MODERATE CONFIDENCE BASED ON ANALYSIS OF
THE CONVECTIVE BANDING SEEN IN THE ANIMATED MSI, WITH SUPPORT
FROM A LOW-RESOLUTION 120552Z ATMS 165 GHZ MICROWAVE IMAGE, WHICH
INDICATED A BROAD AREA OF CURVED CONVECTIVE BANDING ON THE
SOUTHERN SIDE OF THE CENTER. THE INITIAL INTENSITY IS ASSESSED
AT 45 KNOTS WITH HIGH CONFIDENCE BASED ON A SLIGHT HEDGE UPWARD
FROM THE PGTW T2.5 DVORAK INTENSITY ESTIMATE IN LIGHT OF AN
ADVANCED DVORAK TECHNIQUE ESTIMATE OF T3.0 AND A SATELLITE
CONSENSUS ESTIMATE OF 45 KNOTS. ENVIRONMENTAL ANALYSIS INDICATES
THE SYSTEM LIES IN A GENERALLY FAVORABLE ENVIRONMENT WITH LOW
(10-15KT) VERTICAL WIND SHEAR, GOOD DIVERGENT WESTWARD OUTFLOW,
AND WARM (29-30C) SST IN THE SOUTH CHINA SEA JUST EAST OF HAINAN
ISLAND. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A
DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. IN THE NEAR-TERM, TS 18W IS FORECAST TO MAKE LANDFALL ALONG
THE EASTERN SHORE OF HAINAN ISLAND WITHIN THE NEXT HOURS AS IT
CONTINUES TRACKING GENERALLY WESTWARD ALONG THE SOUTHERN
PERIPHERY OF THE DEEP-LAYER STR TO THE NORTH. AFTER LANDFALL,
SOME SLIGHT WEAKENING IS EXPECTED AS THE LLCC INTERACTS WITH THE
RUGGED TERRAIN OF HAINAN, DISRUPTING THE PRIMARY CIRCULATION
CENTER AND CUTTING OFF THE ENERGY SUPPLY. BY ROUGHLY TAU 18
HOWEVER, THE CIRCULATION WILL REEMERGE INTO THE SOUTHERN GULF OF
TONKIN AND REINTENSIFY UNDER FAVORABLE ENVIRONMENTAL CONDITIONS
OF VERY WARM (29-30 DEG CELSIUS), LOW VWS AND DIVERGENT WESTWARD
OUTFLOW. THE SYSTEM IS FORECAST TO REACH A PEAK OF 50 KNOTS BY
TAU 36 BEFORE MAKING LANDFALL ALONG THE NORTH VIETNAMESE
COASTLINE PRIOR TO TAU 48. THERE IS A POSSIBILITY THAT THE
INTENSITY COULD REACH A SLIGHTLY HIGHER INTENSITY NEAR 55 KNOTS
JUST BEFORE LANDFALL, WHICH IS NOT CAPTURED BY THE FORECAST TAUS.
AFTER MAKING LANDFALL OVER NORTHERN VIETNAM, THE SYSTEM WILL
RAPIDLY WEAKEN OVER THE MOUNTAINOUS TERRAIN OF VIETNAM AND
DISSIPATING AS A TROPICAL CYCLONE OVER NORTHERN LAOS BY TAU 72.
NUMERICAL MODELS REMAIN IN GOOD AGREEMENT THOUGH THE ENTIRE
FORECAST PERIOD WITH ONLY MINIMAL SPREAD AFTER LANDFALL IN
VIETNAM. THE JTWC FORECAST TRACK LIES JUST SOUTH OF THE
MULTI-MODEL CONSENSUS THROUGH LANDFALL AND THEN JUST NORTH
THEREAFTER, WITH HIGH CONFIDENCE.//
NNNN

[doomhaMwx]

ZCZC
WHCI40 BABJ 131120
STS 2016 (2016) NANGKA LANDED ON QIONGHAI HAINAN PROVINCE
131120GMT (25m/s)
NNNN

[euro6208]

18W NANGKA 201013 1200 19.0N 110.5E WPAC 50 989