WPAC: KROSA - Post-Tropical

[euro6208]

WDPN33 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KROSA) WARNING NR
027//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 11W (KROSA), LOCATED APPROXIMATELY 212 NM WEST
OF IWO TO, JAPAN, HAS TRACKED NORTHWESTWARD AT 06 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A VERY
EXPANSIVE SYSTEM SPANNING OVER 600NM WITH DEEP BUT WIDELY FRAGMENTED
CONVECTIVE BANDS SPIRALING AROUND A LARGE, RAGGED AND FULLY EXPOSED
LOW-LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH FAIR
CONFIDENCE BASED ON THE CENTER OF THE LLC. THE INITIAL INTENSITY OF
55KTS IS AVERAGED FROM AGENCY DVORAK ESTIMATES RANGING FROM
T3.5/45KTS TO T4.0/65 KTS AND REFLECTS THE SUSTAINED CONVECTIVE
SIGNATURE. UPPER LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH
A LOW DIRECTLY OVER THE LLC THAT IS CAUSING SUBSIDENCE. HOWEVER,
AROUND THE LOW IS A BROAD ANTICYCLONIC OUTFLOW THAT IS PROVIDING
VENTILATION TO THE OUTER CONVECTIVE BANDS. ALONG-TRACK SST AT 30C
REMAINS CONDUCIVE. THE CYCLONE IS TRACKING ALONG THE SOUTHERN
PERIPHERY OF A BUILDING SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. OVER THE NEXT 48 HOURS, TS 11W WILL CONTINUE ON ITS CURRENT
TRACK UNDER THE STR. AFTERWARD, IT WILL TURN POLEWARD AND CREST THE
STR AXIS, MAKING LANDFALL OVER EASTERN KYUSHU AROUND SHORTLY BEFORE
TAU 72. THE MARGINAL CONDITIONS WILL SUSTAIN THE CURRENT INTENSITY AT
BEST UP TO TAU 24. AFTERWARD, INCREASING POLEWARD OUTFLOW AHEAD OF A
MID-LATITUDE TROUGH WILL PROMOTE INTENSIFICATION TO A PEAK OF 65
KNOTS BY TAU 48. NUMERICAL MODELS ARE IN GOOD AGREEMENT, LENDING HIGH
CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST.
C. AFTER TAU 72, LAND INTERACTION, INCREASING VWS, AND COOLER SSTS
IN THE SEA OF JAPAN (SOJ) WILL COMBINE TO GRADUALLY WEAKEN THE SYSTEM
DOWN TO 50KTS AS IT EXITS INTO THE SOJ THEN DOWN TO 30KTS BY TAU 120
AS IT LANDS OVER THE SAKHALIN ISLAND. CONCURRENTLY, BY TAU 96, TS
KROSA WILL BEGIN EXTRA-TROPICAL TRANSITION AS IT ENTERS THE
BAROCLINIC ZONE, BECOMING A COLD CORE LOW BY TAU 120. NUMERICAL
MODELS SPREAD OUT TO OVER 600 NM BY TAU 120 WITH NAVGEM AND JGSM AS
NOTABLE RIGHT OUTLIERS. THERE IS OVERALL MODERATE CONFIDENCE IN THE
JTWC FORECAST TRACK THAT IS LAID JUST TO THE LEFT OF CONSENSUS TO
OFFSET THE UNLIKELY NAVGEM/JGSM SOLUTION THAT DRIVES THE VORTEX INTO
THE STR.//
NNNN

[euro6208]

Interesting.

TXPQ27 KNES 112116
TCSWNP

A. 11W (KROSA)

B. 11/2030Z

C. 24.6N

D. 138.3E

E. THREE/HIMAWARI-8

F. SUBTROPICAL

G. IR/EIR/SWIR

H. REMARKS...THIS ESTIMATE WAS DERIVED USING 4 KM IR DATA. THE
DESIGNATION OF SUBTROPICAL IN THE CASE OF KROSA MERELY MEANS THAT THE
DVORAK TECHNIQUE CANNOT ADEQUATELY ASSESS THE ACTUAL INTENSITY. SINCE
09/1430Z THE CENTER OF CIRCULATION HAS BEEN DEVOID OF ACTIVE DEEP
CONVECTION BY GREATER OR LESSER DEGREES. AS A RESULT DVORAK CURRENT
INTENSITY NUMBERS HAVE STEADILY FALLEN TO THE POINT WHERE THEY ASSESS
KROSA AS A MINIMAL TROPICAL STORM. OFFICIAL ESTIMATES OF WIND SPEED AND
PRESSURE FROM RSMC TOKYO AND JTWC ARE HIGHER AND LOWER, RESPECTIVELY,
THAN SAB DVORAK ESTIMATES. OBJECTIVE TECHNIQUES, WITH THE NOTABLE
EXCEPTION OF THE ADT, ALSO SUGGEST THAT THE SYSTEM IS MORE INTENSE THAN
DVORAK ESTIMATES ALLOW. THEREFORE THIS WILL BE THE FINAL BULLETIN UNTIL
SUCH TIME AS SATELLITE ANALYSIS SUGGESTS THAT THE DVORAK TECHNIQUE CAN
BETTER ASSESS THE ACTUAL INTENSITY OF THIS SYSTEM.

I. ADDL POSITIONS

NIL


...TURK

[euro6208]

[euro6208]

The size of this thing is super incredible. Wow.

[Hayabusa]

It's been a while "Very Large"

STS 1910 (Krosa)
Issued at 09:45 UTC, 12 August 2019

<Analysis at 09 UTC, 12 August>
Scale Very large
Intensity -
Center position N25°25' (25.4°)
E137°30' (137.5°)
Direction and speed of movement NW 15 km/h (7 kt)
Central pressure 965 hPa
Maximum sustained wind speed 30 m/s (60 kt)
Maximum wind gust speed 45 m/s (85 kt)
≥ 50 kt wind area ALL 330 km (180 NM)
≥ 30 kt wind area S 1100 km (600 NM)
N 560 km (300 NM)

[1900hurricane]

 https://twitter.com/WXappraiser/status/1160940509960888320

[euro6208]

WDPN33 PGTW 130900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KROSA) WARNING NR
031//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 11W (KROSA), LOCATED APPROXIMATELY 422 NM
SOUTH-SOUTHEAST OF IWAKUNI, JAPAN, HAS TRACKED WEST-NORTHWESTWARD
AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) SHOWS A BROAD SYSTEM WITH FRAGMENTED CONVECTIVE BANDS
SPIRALING IN FROM THE SOUTHWEST INTO A LARGE, RAGGED AND FULLY EXPOSED
LOW-LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS BASED WITH FAIR
CONFIDENCE ON THE ROUGH CENTROID OF ROTATION IN THE MSI IMAGERY,
ALTHOUGH MULTIPLE SMALL MESOVORTICES ARE ALSO VISIBLE IN THE LLC. THE
INITIAL INTENSITY OF 45 KNOTS AGREES WITH THE PGTW DVORAK CURRENT
INTENSITY ESTIMATE OF T3.0 (45 KTS) AND IS SLIGHTLY BELOW A 130326Z
SATCON ESTIMATE OF 48 KTS. UPPER LEVEL ANALYSIS INDICATES A
MARGINAL ENVIRONMENT WITH AN UPPER LEVEL LOW DIRECTLY OVER THE LLC
WHICH IS INHIBITING CENTRAL CONVECTION. THE RADIUS OF MAXIMUM WINDS,
LIKE THE CONVECTION, IS DISPLACED FAR FROM THE CENTER. SEA SURFACE
TEMPERATURES (SST) REMAIN CONDUCIVE (29-30 DEGREES CELSIUS). THE
CYCLONE IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF AN EXTENSION
OF THE SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. OVER THE NEXT 36 HOURS, TS 11W WILL CONTINUE ON ITS CURRENT
TRACK UNDER THE INFLUENCE OF THE PREVIOUSLY MENTIONED STR. NEAR TAU
36, A MIDLATITUDE TROUGH WILL APPROACH FROM THE WEST, ERODING THE STR
AND ALLOWING TS 11W TO RECURVE POLEWARD AROUND THE STR AXIS, SKIRTING
WESTERN SHIKOKU NEAR TAU 36. THE MARGINAL CONDITIONS WILL SUSTAIN THE
CURRENT INTENSITY UP TO TAU 12. AFTERWARD, INCREASING POLEWARD OUTFLOW
AHEAD OF THE AFOREMENTIONED TROUGH WILL ENABLE A SLIGHT
INTENSIFICATION TO A PEAK OF 50 KNOTS BY TAU 24. LAND INTERACTION,
INCREASING VERTICAL WIND SHEAR (VWS), AND COOLER SST (24-26 DEGREES
CELSIUS) IN THE SEA OF JAPAN (SOJ) WILL COMBINE TO GRADUALLY WEAKEN
THE SYSTEM DOWN TO 40 KNOTS BY TAU 72 AS IT EXITS INTO THE SOJ.
NUMERICAL MODELS ARE IN GOOD CROSS-TRACK AGREEMENT, WITH THE EXCEPTION
OF NAVGEM, WHICH IS EXPECTING AN EARLIER RECURVE AND TRACKS MUCH
FURTHER EAST THAN THE OTHER MODELS. ADDITIONALLY, ECMWF AND UKMET
PREDICT FASTER ALONG-TRACK SPEEDS THAN DO GFS AND THE GFS ENSEMBLE.
THE JTWC FORECAST TRACK IS HEDGED SLIGHTLY AHEAD AND TO THE WEST OF
THE MULTI-MODEL CONSENSUS, TOWARDS THE ECMWF SOLUTION, WITH HIGH
CONFIDENCE.
C. AFTER TAU 72, COOLER SSTS IN THE SOJ WILL COMBINE WITH
INCREASING VWS TO RAPIDLY WEAKEN THE SYSTEM TO 35 KNOTS BY TAU 96 AS
IT ACCELERATES INTO THE NORTHERN SOJ WEST OF HOKKAIDO. TS 11W WILL
ALSO BEGIN EXTRA-TROPICAL TRANSITION AS IT INTERACTS WITH THE
AFOREMENTIONED TROUGH. WITH THE EXCEPTION OF NAVGEM, THE CROSS-TRACK
MODEL SPREAD BECOMES 250 NM BY TAU 96. THERE IS OVERALL MODERATE
CONFIDENCE IN THE JTWC FORECAST TRACK FOR THIS PORTION OF THE FORECAST
THAT IS LAID JUST TO THE LEFT OF CONSENSUS, TOWARDS THE ECMWF
SOLUTION, AND HEDGED AWAY FROM THE NAVGEM SOLUTION THAT DRIVES TS 11W
INTO THE RIDGING.//
NNNN

[somethingfunny]

Reintensification or not this will be a very wet storm for Japan.

[Hayabusa]

Hmm double red circles?

STS 1910 (Krosa)
Issued at 17:45 UTC, 14 August 2019

<Analysis at 17 UTC, 14 August>
Scale Large
Intensity -
Center position N31°35' (31.6°)
E132°30' (132.5°)
Direction and speed of movement N 15 km/h (9 kt)
Central pressure 965 hPa
Maximum sustained wind speed 30 m/s (55 kt)
Maximum wind gust speed 40 m/s (80 kt)
≥ 50 kt wind area E 330 km (180 NM)
W 170 km (90 NM)
≥ 30 kt wind area E 600 km (325 NM)
W 500 km (270 NM)

[euro6208]

WDPN33 PGTW 150900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KROSA) WARNING NR
039//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 11W (KROSA), LOCATED APPROXIMATELY 35 NM
SOUTHEAST OF IWAKUNI, JAPAN, HAS TRACKED NORTHWARD AT 15 KNOTS KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
SHOWS THE SYSTEM RAPIDLY ERODING AFTER IT MADE LANDFALL OVER WESTERN
SHIKOKU AND CROSSING RUGGED TERRAIN INTO WESTERN HONSHU. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A COMPOSITE
REFLECTIVITY RADAR LOOP FROM JMA. THE INITIAL INTENSITY IS BASED ON
AN OVERALL ASSESSMENT OF AGENCY DVORAK ESTIMATES AND NUMEROUS SURFACE
OBSERVATIONS. DESPITE INCREASING VERTICAL WIND SHEAR AND LAND
INTERACTION, UPPER LEVEL OUTFLOW REMAINS ROBUST, PROVIDING
VENTILATION TO THE DECAYING CONVECTION. TS 11W IS TRACKING ALONG THE
WESTERN EDGE OF A SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 11W HAS CRESTED THE STR AXIS AND WILL NOW TRACK MORE
NORTH-NORTHEASTWARD, EXITING INTO THE SEA OF JAPAN (SOJ) JUST AFTER
TAU 06, BEFORE ACCELERATING NORTHEASTWARD TOWARD HOKKAIDO. THE
ADDITION OF COOLER SST IN THE SOJ WILL ACCELERATE THE CONVECTIVE
DEGRADATION. CONCURRENTLY, BY TAU 12, THE SYSTEM WILL BEGIN
EXTRA-TROPICAL TRANSITION, BECOMING A GALE-FORCE COLD CORE LOW WITH
AN EXPANSIVE WIND FIELD BY TAU 24. DYNAMIC MODEL GUIDANCE IS IN TIGHT
AGREEMENT, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN