WPAC: ATSANI - Post-Tropical

[Hayabusa]

FYI this is now a 40 kt TS, last time I checked it was since 18Z.

TS 2020 (Atsani)
Issued at 22:05 UTC, 31 October 2020

<Analysis at 21 UTC, 31 October>
Scale -
Intensity -
Center position N15°10' (15.2°)
E135°20' (135.3°)
Direction and speed of movement WNW 30 km/h (15 kt)
Central pressure 998 hPa
Maximum wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
≥ 30 kt wind area ALL 280 km (150 NM)

<Forecast for 09 UTC, 1 November>
Intensity -
Center position of probability circle N17°05' (17.1°)
E133°00' (133.0°)
Direction and speed of movement NW 30 km/h (15 kt)
Central pressure 994 hPa
Maximum wind speed near center 23 m/s (45 kt)
Maximum wind gust speed 35 m/s (65 kt)
Radius of probability circle 85 km (45 NM)

<Forecast for 21 UTC, 1 November>
Intensity -
Center position of probability circle N18°40' (18.7°)
E130°35' (130.6°)
Direction and speed of movement NW 25 km/h (14 kt)
Central pressure 992 hPa
Maximum wind speed near center 25 m/s (50 kt)
Maximum wind gust speed 35 m/s (70 kt)
Radius of probability circle 120 km (65 NM)

<Forecast for 18 UTC, 2 November>
Intensity -
Center position of probability circle N19°50' (19.8°)
E129°05' (129.1°)
Direction and speed of movement NW 10 km/h (6 kt)
Central pressure 980 hPa
Maximum wind speed near center 30 m/s (60 kt)
Maximum wind gust speed 45 m/s (85 kt)
Radius of probability circle 165 km (90 NM)
Storm warning area ALL 240 km (130 NM)

<Forecast for 18 UTC, 3 November>
Intensity -
Center position of probability circle N19°10' (19.2°)
E129°10' (129.2°)
Direction and speed of movement Almost stationary
Central pressure 980 hPa
Maximum wind speed near center 30 m/s (60 kt)
Maximum wind gust speed 45 m/s (85 kt)
Radius of probability circle 260 km (140 NM)
Storm warning area ALL 330 km (180 NM)

<Forecast for 18 UTC, 4 November>
Intensity -
Center position of probability circle N17°35' (17.6°)
E126°50' (126.8°)
Direction and speed of movement WSW 15 km/h (7 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 480 km (260 NM)
Storm warning area ALL 560 km (300 NM)

<Forecast for 18 UTC, 5 November>
Intensity -
Center position of probability circle N17°40' (17.7°)
E121°05' (121.1°)
Direction and speed of movement W 25 km/h (14 kt)
Central pressure 985 hPa
Maximum wind speed near center 30 m/s (55 kt)
Maximum wind gust speed 40 m/s (80 kt)
Radius of probability circle 650 km (360 NM)
Storm warning area ALL 700 km (390 NM)

[ElectricStorm]

Now that Goni is going to start moving out/weakening, Atsani is next in line for a potential strong Philippine threat, this time for Luzon

[euro6208]

WDPN32 PGTW 010300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W (ATSANI)
WARNING NR 011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION 23W (ATSANI), LOCATED
APPROXIMATELY 779 NM EAST OF MANILA, PHILIPPINES, HAS
TRACKED WEST-NORTHWESTWARD AT 19 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
REVEALS THAT THE CENTRAL CONVECTION HAS STRENGTHENED OVER
THE PAST 6 HOURS, HOWEVER THE OVERALL CONVECTIVE STRUCTURE
HAS FAILED TO FURTHER ORGANIZE. THE INITIAL POSITION IS
PLACED WITH LOW CONFIDENCE BASED ON LOW LEVEL FEATURES IN THE
MSI LOOP. THE INITIAL INTENSITY OF 30 KTS IS PLACED WITH FAIR
CONFIDENCE BASED ON MULTI-AGENCY DVORAK CURRENT INTENSITY
ESTIMATES OF T2.0 (PGTW, 30 KTS) AND T2.5 (RJTD, 35 KTS). THE
ENVIRONMENT IS OVERALL UNFAVORABLE WITH MODERATE (20-25 KTS)
VERTICAL WIND SHEAR (VWS) AND WEAK OUTFLOW ALOFT OFFSET ONLY
SLIGHTLY BY WARM (39-30 CELSIUS) SEA SURFACE TEMPERATURES
(SST). THE CYCLONE IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY
OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TD 23W WILL CONTINUE ON ITS CURRENT TRACK IN THE
PHILIPPINE SEA UNDER THE AFOREMENTIONED STR. AFTER TAU 24, A
SHORTWAVE MIDLATITUDE TROUGH APPROACHING FROM THE NORTHWEST WILL
ERODE AND SPLIT THE STR AND PULL THE CYCLONE POLEWARD INTO THE
COL ZONE BETWEEN THE RIDGES. THE ENVIRONMENT IS FORECAST TO
IMPROVE SLIGHTLY AS VWS WEAKENS IN THE COL ZONE AND POLEWARD
OUTFLOW IMPROVES. THE SYSTEM IS FORECAST TO STEADILY INTENSIFY
DURING THIS TIME TO 60 KTS BY TAU 72, HOWEVER, THERE REMAINS THE
POSSIBILITY OF RAPID INTENSIFICATION DURING THIS TIME, DEPENDING
ON THE TIMING AND MAGNITUDE OF THE INTERACTION BETWEEN THE UPPER
LEVEL TROUGH AND THE STEERING RIDGE. NUMERICAL MODEL TRACK
GUIDANCE IS IN FAIR AGREEMENT UP TO TAU 24. AFTERWARD, NAVGEM
DIVERGES TO THE RIGHT OF THE MODEL ENVELOPE. ALONG TRACK SPREAD
IN SOLUTIONS ALSO DIVERGE AFTER THIS TIME DUE TO UNCERTAINTY IN
THE TROUGH-RIDGE INTERACTION. THIS SPREAD IN ALONG TRACK
SOLUTIONS LENDS ONLY FAIR CONFIDENCE IN THIS INITIAL PORTION OF
THE JTWC FORECAST TRACK, WHICH IS PLACED SLIGHTLY LEFT OF THE
MULTI-MODEL CONSENSUS TO OFFSET THE UNLIKELY NAVGEM SOLUTION
THAT DRIVES THE SYSTEM CENTER INTO THE STR.
C. IN THE EXTENDED FORECAST, THE SECONDARY STR BEHIND THE
SHORTWAVE TROUGH WILL ASSUME STEERING AND SLOWLY DRIVE TD 23W WEST-
SOUTHWESTWARD THEN WESTWARD. ENVIRONMENTAL CONDITIONS ARE FORECAST
TO IMPROVE EVEN MORE WITH DECREASED VWS (10-15KTS) AND THE ADDITION
OF AN EQUATORWARD OUTFLOW CHANNEL. THESE CONDITIONS, COUPLED WITH
CONTINUED WARM SST, WILL ALLOW FOR FURTHER INTENSIFICATION TO 80KTS
BY TAU 120, BY WHICH TIME IT WILL HAVE MADE LANDFALL OVER LUZON.
NUMERICAL MODELS SIGNIFICANTLY DIVERGE TO 490 NM BY TAU 120 WITH
VARYING TRACK SPEEDS, LENDING POOR CONFIDENCE IN THE EXTENDED
PORTION OF THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

00z GFS stronger. 982 mb peak and landfalls in northern Luzon.

[1900hurricane]

After a really lackluster 12Z cycle, the 18Z EPS has picked back up a little with Atsani.

[euro6208]

[Hayabusa]

Now where will this one go and how strong it would be.

[euro6208]

Forecast to do a 360 loop.

WDPN32 PGTW 010900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W (ATSANI)
WARNING NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION 23W (ATSANI), LOCATED APPROXIMATELY 689
NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD
AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY (MSI) SHOWS A WEAK SYSTEM THAT HAS MAINTAINED
AN OVERALL POORLY-ORGANIZED CONVECTIVE STRUCTURE. THE INITIAL
POSITION IS PLACED WITH LOW CONFIDENCE BASED ON LOW-CLOUD TRACING
INTO AN OBSCURED LOW LEVEL CIRCULATION IN THE MSI LOOP. THE INITIAL
INTENSITY OF 30 KTS IS BASED ON THE DVORAK ESTIMATE OF T2.0/30KTS
FROM PGTW. THE ENVIRONMENT IS OVERALL UNFAVORABLE WITH MODERATE
(20-25KT) VERTICAL WIND SHEAR (VWS) AND WEAK OUTFLOW ALOFT OFFSET
BY WARM (29-30C) SEA SURFACE TEMPERATURES (SST). THE CYCLONE IS
TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TD 23W WILL CONTINUE ON ITS CURRENT TRACK IN THE PHILIPPINE
SEA UNDER THE AFOREMENTIONED STR. AFTER TAU 24, A SHORTWAVE
MIDLATITUDE TROUGH APPROACHING FROM THE NORTHWEST WILL ERODE AND
SPLIT THE STR AND PULL THE CYCLONE POLEWARD INTO A QUASI-STATIONARY
(QS) STATE IN THE COL ZONE BETWEEN THE TWO RIDGES. THE ENVIRONMENT
IS FORECAST TO IMPROVE SLIGHTLY AS VWS WEAKENS AND POLEWARD OUTFLOW
IMPROVES, FUELING A STEADY INTENSIFICATION TO 60KTS BY TAU 72.
NUMERICAL MODELS ARE IN GOOD AGREEMENT UP TO TAU 24 WITH NAVGEM
THE SOLE OUTLIER TO THE RIGHT. AFTERWARD, THE MODELS DIVERGE
SIGNIFICANTLY WITH VARYING SOLUTIONS IN THE DURATION OF QS STATE
IN THE COL, LENDING LOW CONFIDENCE IN THIS PORTION OF THE JTWC
FORECAST TRACK.
C. IN THE EXTENDED TAUS, THE SECONDARY STR BEHIND THE SHORTWAVE
TROUGH WILL ASSUME STEERING AND SLOWLY DRIVE TD 23W WESTWARD.
ENVIRONMENTAL CONDITIONS ARE FORECAST TO IMPROVE EVEN MORE WITH
DECREASED VWS (10-15KTS) AND THE ADDITION OF AN EQUATORWARD OUTFLOW
CHANNEL. THESE CONDITIONS, COUPLED WITH CONTINUED WARM SST, WILL
ALLOW FOR FURTHER INTENSIFICATION TO 85KTS AS IT CROSSES THE LUZON
STRAIT. NUMERICAL MODELS SIGNIFICANTLY DIVERGE TO 400 NM BY TAU 120
WITH VARYING TRACK SPEEDS, LENDING POOR CONFIDENCE IN THE EXTENDED
PORTION OF THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

Strongest run so far.

[euro6208]

[euro6208]

CI# /Pressure/ Vmax
3.3 / 994.4mb/ 51.0kt


Final T# Adj T# Raw T#
3.0 2.6 2.4

[euro6208]

If this was in the recon equipped Atlantic, it would be alot stronger.

[ElectricStorm]

Still no upgrade
23W ATSANI 201101 1200 16.9N 131.5E WPAC 30 1004

[1900hurricane]

Might be on the road to re-consolidation. At the very least, you can tell it is a distinct feature separate from Goni's outflow again.

[euro6208]

 https://twitter.com/ptccfeed/status/1322812173949698048




 https://twitter.com/ptccfeed/status/1322890413535944704

[euro6208]

GLOBAL MODEL DATA TIME 00UTC 01.11.2020



TROPICAL DEPRESSION ATSANI ANALYSED POSITION : 16.3N 134.4E



VERIFYING TIME POSITION STRENGTH TENDENCY

-------------- -------- -------- --------

00UTC 01.11.2020 16.3N 134.4E WEAK

12UTC 01.11.2020 17.2N 131.3E WEAK LITTLE CHANGE

00UTC 02.11.2020 18.4N 129.4E WEAK LITTLE CHANGE

12UTC 02.11.2020 19.5N 129.1E WEAK LITTLE CHANGE

00UTC 03.11.2020 19.9N 129.6E MODERATE LITTLE CHANGE

12UTC 03.11.2020 20.0N 130.0E MODERATE INTENSIFYING SLIGHTLY

00UTC 04.11.2020 19.8N 129.6E MODERATE INTENSIFYING SLIGHTLY

12UTC 04.11.2020 19.2N 128.2E STRONG INTENSIFYING RAPIDLY

00UTC 05.11.2020 19.0N 125.7E INTENSE INTENSIFYING RAPIDLY

12UTC 05.11.2020 19.2N 122.8E INTENSE INTENSIFYING SLIGHTLY

00UTC 06.11.2020 20.0N 119.6E STRONG WEAKENING SLIGHTLY

12UTC 06.11.2020 20.4N 116.9E STRONG WEAKENING RAPIDLY

00UTC 07.11.2020 20.5N 114.4E MODERATE WEAKENING SLIGHTLY

[euro6208]

[mrbagyo]

still a mess

[euro6208]

Looks like JTWC has been underestimating this for quite some time. Lack of recon...

[mrbagyo]

Looks like it's finally getting its act together now