WPAC: HAISHEN - Post-Tropical

[euro6208]

00Z EURO

[euro6208]

2 runs in the row of showing peak of 920's.

[Hayabusa]

907 mb minimum


High res Euro run is 920 mb

[aspen]

These are some of the most aggressive model runs I’ve ever seen. The GFS is continuously in the 920s, the Euro is down to 926 mbar, and the NAVGEM gets all the way down to 903 mbar.

Funny how the models are so aggressive with the least active basins this year, and don’t show anything in the Atlantic until it has already formed.

[Hayabusa]

11W ELEVEN 200831 1200 22.9N 145.8E WPAC 25 1006

[aspen]

If Maysak has struggled to undergo RI and build an eyewall despite such a favorable environment and aggressive model support, then should we believe the even more aggressive model runs for 11W?

[doomhaMwx]

I think they upgraded a little bit early. Latest ASCAT pass shows a sharp trough rather than a TC.

[Hayabusa]

WDPN32 PGTW 311500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 11W (ELEVEN) WARNING
NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 11W (ELEVEN), LOCATED APPROXIMATELY 272 NM
EAST-SOUTHEAST OF IWO TO, JAPAN, HAS TRACKED SOUTHWESTWARD AT 12 KNOTS
(KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS CONVECTIVE BANDING WRAPPING UNDER FLARING DEEP
CONVECTION OVERHEAD THE LOW LEVEL CIRCULATION CENTER (LLCC). A 311107Z
ASCAT-A IMAGE DEPICTS A SLIGHTLY ELONGATED CIRCULATION WITH A SWATH OF
25-30 KT WINDS DISPLACED WITHIN THE DEEP CONVECTION TO THE SOUTHEAST
OF THE LLCC AND WEAKER (15-20 KT) WINDS ELSEWHERE. BASED ON THE
AFOREMENTIONED ASCAT IMAGE ALONG WITH DVORAK CURRENT INTENSITY
ESTIMATES OF T1.0-2.0 (25-30 KTS) BY PGTW, RJTD, AND KNES, THE INITIAL
INTENSITY IS SET AT 25 KTS WITH GOOD CONFIDENCE. ENVIRONMENTAL
ANALYSIS REVEALS THAT TD 11W IS SUPPORTED BY ROBUST EQUATORWARD UPPER
LEVEL OUTFLOW AND WARM (30-31 CELSIUS) SEA SURFACE TEMPERATURES (SST)
THAT ARE BEING OFFSET BY MODERATE (20-25 KT) VERTICAL WIND SHEAR
(VWS). OF NOTE, TD 11W IS CURRENTLY TRACKING SOUTHWESTWARD UNDER THE
COMBINED STEERING INFLUENCE OF A SUBTROPICAL RIDGE (STR) TO THE WEST
AND AN EXTENSION OF THE STR TO THE NORTHEAST.
3. FORECAST REASONING.
A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE FOR THIS SYSTEM
AND SETS THE FORECAST PHILOSOPHY.
B. IN THE NEAR-TERM, TD 11W WILL TRACK WEST-SOUTHWESTWARD UNDER THE
COMBINED STEERING INFLUENCE OF THE STR TO THE WEST AND THE STR
EXTENSION. DURING THIS TIME, THE SYSTEM WILL EXPERIENCE FAVORABLE SST
AND CONTINUED DIVERGENCE ALOFT, BUT INTENSIFICATION WILL BE LIMITED
DUE TO HIGH VWS VALUES. CONSEQUENTLY, TD 11W IS EXPECTED TO GRADUALLY
INTENSIFY TO 40 KTS BY TAU 24. AS A MIDLATITUDE SHORTWAVE TROUGH
APPROACHES FROM THE WEST, THE STR TO THE WEST WILL BEGIN TO ERODE
WHILE THE STR TO THE NORTHEAST WILL BUILD, BECOMING THE PRIMARY
STEERING MECHANISM. UNDER ITS INFLUENCE, THE SYSTEM WILL SLOWLY TURN
WESTWARD THEN NORTHWESTWARD THROUGH TAU 72 AS IT TRACKS ALONG THE
PERIPHERY. VWS VALUES DECREASE AFTER TAU 24 ALLOWING TD 11W TO
STEADILY INTENSIFY ALONG THE FORECAST TRACK. NUMERICAL MODEL GUIDANCE
IS IN FAIR AGREEMENT WITH THE GFS AND UKMET ENSEMBLE SOLUTIONS AS
OUTLIERS TO THE SOUTH AND THE JGSM SOLUTION TO THE NORTH. THE JTWC
FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL CONSENSUS WITH FAIR
CONFIDENCE. ADDITIONALLY, THE ECMWF ENSEMBLE IS IN GOOD AGREEMENT WITH
SPREAD SLOWLY INCREASING IN THE LATER TAUS.
C. IN THE EXTENDED PERIOD, THE SYSTEM WILL CONTINUE TO TRACK
NORTHWARD ALONG THE PERIPHERY OF A STR TO THE EAST. THE SYSTEM WILL
STEADILY INTENSIFY TO 85 KTS BY TAU 120 DUE TO CONTINUED FAVORABLE
ENVIRONMENTAL CONDITIONS OF LOW VWS, WARM SST, AND CONDUCIVE OCEAN
HEAT CONTENT VALUES. HOWEVER, NUMERICAL MODEL GUIDANCE DIVERGES
THROUGHOUT THE FORECAST PERIOD, INCREASING TO A CROSS TRACK SPREAD OF
228 NM BY TAU 120. THEREFORE, DUE TO THE UNCERTAINTY (LARGE SPREAD) IN
THE MODEL SOLUTIONS, THERE IS OVERALL FAIR CONFIDENCE IN THE JTWC
FORECAST TRACK WHICH IS PLACED ALONG THE MULTI-MODEL CONSENUS.//
NNNN

[Hayabusa]

Epic monster run.

[Highteeld]

Deepest run I have seen for the GFS since the upgrade

[mrbagyo]

Oh wow if this materialize

[1900hurricane]

Here's a first (low confidence) forecast for 11W.

 https://twitter.com/1900hurricane/status/1300487920139210752



 https://twitter.com/1900hurricane/status/1300487922861383681



 https://twitter.com/1900hurricane/status/1300487924702683138

[Hayabusa]

Uh-huh

[aspen]

Uh-huh
https://i.imgur.com/ZvGnF2v.png

This going to bust even worse than Nisarga.

[Hayabusa]

Hmm almost nuclear

[Hayabusa]

JTWC up to TS

11W ELEVEN 200831 1800 22.1N 144.9E WPAC 35 1002

[Hayabusa]

[aspen]

Just like Maysak, 11W will spend its early development stages moving slowly over a region of high OHC, which should prevent upwelling from becoming an issue. It’ll hit an even higher pocket of OHC on Wednesday, around the same time it should be ready for RI.

[aspen]

18z GFS is down to 949 mbar in 72 hours. Decent chance this run gets below 910 mbar.

[euro6208]

WDPN32 PGTW 312100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (ELEVEN) WARNING
NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 11W (ELEVEN), LOCATED APPROXIMATELY 256 NM
SOUTHEAST OF IWO TO, JAPAN, HAS TRACKED SOUTHWESTWARD AT 12 KNOTS
(KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY SHOWS FLARING DEEP CENTRAL CONVECTION SHEARED
SOUTHWESTWARD OF A PARTIALLY EXPOSED LOW LEVEL CIRCULATION. THE
INITIAL POSITION IS EXTRAPOLATED FROM THE EIR LOOP AND FROM A NOTCH
FEATURE IN THE 311625Z AMSR2 MICROWAVE IMAGE WITH LOW CONFIDENCE. THE
INITIAL INTENSITY OF 35KTS IS BASED ON THE DVORAK ESTIMATE OF
T2.5/35KTS FROM PGTW AND REFLECTS THE IMPROVED EIR SIGNATURE.
ANALYSIS INDICATES TS 11W IS UNDER A MARGINAL ENVIRONMENT WITH STRONG
EQUATORWARD UPPER LEVEL OUTFLOW AND WARM (30-31 CELSIUS) SEA SURFACE
TEMPERATURES (SST) THAT ARE BEING OFFSET BY MODERATE (20-25KT)
NORTHEASTERLY VERTICAL WIND SHEAR (VWS). THE CYCLONE IS TRACKING
UNDER THE COMBINED STEERING INFLUENCE OF A SUBTROPICAL RIDGE (STR) TO
THE WEST AND AN EXTENSION OF THE STR TO THE NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE LAST PROGNOSTIC REASONING MESSAGE.
B. TS 11W WILL CONTINUE ON ITS CURRENT TRACK UP TO TAU 24 WITH
MINIMAL INTENSIFICATION TO 55KTS DUE TO THE MARGINAL ENVIRONMENT.
AFTERWARD, A MIDLATITUDE SHORTWAVE TROUGH APPROACHING FROM THE
NORTHWEST WILL BEGIN TO ERODE THE STR TO THE WEST. THE STR TO THE
NORTHEAST, ON THE OTHER HAND, WILL BUILD AND BECOME THE PRIMARY
STEERING MECHANISM AND DRIVE THE SYSTEM SLOWLY WESTWARD THEN
NORTHWESTWARD. VWS VALUES WILL DECREASE AFTER TAU 24 ALLOWING TS 11W
TO STEADILY INTENSIFY ALONG THE FORECAST TRACK TO 95KTS BY TAU 72.
NUMERICAL MODELS ARE IN FAIR AGREEMENT BUT GIVEN THE COMPLEX STEERING
AND THE FORMATIVE NATURE OF THE CYCLONE, THERE IS LOW CONFIDENCE IN
THIS PORTION OF THE JTWC TRACK FORECAST.
C. BEYOND TAU 72, TS 11W WILL CONTINUE TO TRACK NORTHWESTWARD
ALONG THE PERIPHERY OF THE DOMINANT STR TO THE EAST. THE SYSTEM WILL
STEADILY INTENSIFY TO 115 KTS BY TAU 120 DUE TO CONTINUED FAVORABLE
ENVIRONMENTAL CONDITIONS OF LOW VWS, WARM SST, AND CONDUCIVE OCEAN
HEAT CONTENT VALUES. NUMERICAL MODELS ARE IN FAIR AGREEMENT IN THE
LATER TAUS, HOWEVER, GIVEN THE INITIAL TRACK UNCERTAINTY, THERE IS
ALSO A LOW CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC TRACK
FORECAST.
NNNN