WPAC: LEEPI - Post-Tropical

[NotoSans]

Can anyone just change the title because it is now tropical storm LEEPI.

[cycloneye]

Can anyone just change the title because it is now tropical storm LEEPI.

Made the change.

[mrbagyo]

Leepi is now sporting a microwave eye.

[mrbagyo]

CURRENT ESTIMATE
Date (mmddhhmm): 08120840
SATCON: MSLP = 973 hPa MSW = 75 knots
SATCON Member Consensus: 72.0 knots
Pressure -> Wind Using SATCON MSLP: 82 knots
Distance to Outer Closed Isobar Used is 125 nm
Eye Size Correction Used is 1.8 knots Source: MW

Member Estimates

ADT: 972 hPa 77 knots Scene: CDO Date: AUG120910
CIMSS AMSU: 975 hPa 63 knots Bias Corr: 0 (MW) Date: 08120606
ATMS: 985.9 hPa 56.6 knots Date: 08120339
SSMIS: 980.0 hPa 71.0 knots Date: 08120840
CIRA ATMS: hPa knots Date:

[euro6208]

Again forecast to become a typhoon.

WDPN31 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (LEEPI) WARNING NR
06//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 19W (LEEPI), LOCATED APPROXIMATELY 126 NM
SOUTH-SOUTHEAST OF IWO TO, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT
13 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY DEPICTS A MIDGET SYSTEM WITH A COMPACT CORE OF
DEEP CONVECTION AND A DEEP CONVECTIVE BAND OVER THE EASTERN
SEMICIRCLE. A 120402Z AMSR2 89GHZ IMAGE SHOWS A 90NM DIAMETER
EYEWALL SURROUNDING A SMALL MICROWAVE EYE FEATURE. WHILE THE SYSTEM
CONTINUES TO STRUGGLE TO FORM AN EYE, EIR AND MICROWAVE IMAGERY
INDICATE A CONSOLIDATED LOW-LEVEL CIRCULATION CENTER, THEREFORE, THE
INITIAL INTENSITY REMAINS ASSESSED AT 60 KNOTS. THIS ESTIMATE IS
HEDGED ABOVE DVORAK INTENSITY ESTIMATES OF T3.5 (55 KNOTS) FROM KNES
AND PGTW BASED ON OBJECTIVE DVORAK ESTIMATES AS HIGH AS 4.4 (ROUGHLY
75 KNOTS) AND A UW-CIMSS SATCON ESTIMATE OF 68 KNOTS. ENVIRONMENTAL
CONDITIONS REMAIN FAVORABLE WITH ENHANCED POLEWARD OUTFLOW INTO A
TUTT CELL TO THE NORTHEAST, HOWEVER, THIS OUTFLOW CHANNEL APPEARS TO
BE GRADUALLY WEAKENING DUE TO INCREASING CONVERGENT FLOW OVER THE
NORTHERN PERIPHERY OF THE SYSTEM AS EVIDENT IN ANIMATED WATER VAPOR
IMAGERY. TS 19W IS TRACKING NORTH-NORTHWESTWARD ALONG THE WESTERN
PERIPHERY OF A SUBTROPICAL RIDGE (STR) POSITIONED EAST AND NORTHEAST
OF THE SYSTEM.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TS 19W IS FORECAST TO TRACK NORTHWESTWARD ALONG THE WESTERN
PERIPHERY OF THE STR POSITIONED TO THE EAST THROUGH TAU 24 THEN WEST-
NORTHWESTWARD THROUGH TAU 72 AS IT TRANSITIONS TO THE STEERING
INFLUENCE OF THE STR OVER WESTERN JAPAN. TS 19W IS EXPECTED TO
INTENSIFY TO A PEAK INTENSITY OF 65 KNOTS BY TAU 12 WITH SOME
UNCERTAINTY IN THE EXACT PEAK DUE TO THE COMPACT NATURE OF THE
SYSTEM. AS THE SYSTEM TRACKS FURTHER NORTHWEST, VERTICAL WIND SHEAR
IS FORECAST TO INCREASE TO MODERATE TO STRONG LEVELS, WHICH WILL
SERVE TO WEAKEN THE SYSTEM. ADDITIONALLY, TS 19W WILL BECOME
EMBEDDED WITHIN THE NORTHERN PERIPHERY OF A BROAD SYSTEM FORECAST TO
DEVELOP EAST OF TAIWAN AFTER TAU 48. CONSEQUENTLY, TS 19W SHOULD
DISSIPATE BY TAU 72 DUE TO THE OVERALL MARGINAL CONDITIONS.
NUMERICAL MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH TAU 72,
THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

TPPN13 PGTW 120908

A. TROPICAL STORM 19W (LEEPI)

B. 12/0850Z

C. 23.11N

D. 141.90E

E. THREE/HMWRI8

F. T3.5/3.5/D1.0/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 13A/PBO TIGHTLY CURVED BNDG/ANMTN. CNVCTN WRAPS .80
ON LOG10 SPIRAL YIELDING A DT OF 3.5. MET AND PT AGREE. DBO DT.

I. ADDITIONAL POSITIONS: NONE


VEERKAMP

[euro6208]

60 knots seems like a good estimate.

[euro6208]

SSD at 4.0

TXPQ21 KNES 120946
TCSWNP

A. 19W (LEEPI)

B. 12/0830Z

C. 23.2N

D. 142.0E

E. ONE/HIMAWARI-8

F. T4.0/4.0/D1.5/24HRS

G. IR/EIR/AMSR2/AMSU

H. REMARKS...THIS INTENSITY ESTIMATE WAS DERIVED USING 4 KM IR
DATA. 0840Z SSMIS SHOWS AN EYE FEATURE. OW EYE SURROUNDED BY DG AND
EMBEDDED IN OW YIELDS A DT OF 4.0. NO EYE ADJUSTMENT. MET IS 3.5 AND PT
IS 4.0. FT IS BASED ON DT.

I. ADDL POSITIONS

12/0402Z 22.4N 142.3E AMSR2
12/0607Z 22.8N 142.1E AMSU


...RAMIREZ

[euro6208]

That was quick...

[euro6208]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 9.0
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 12 AUG 2018 Time : 111000 UTC
Lat : 23:38:47 N Lon : 141:09:30 E


CI# /Pressure/ Vmax
4.5 / 971.5mb/ 77.0kt


Final T# Adj T# Raw T#
4.2 3.9 3.0

Center Temp : -62.6C Cloud Region Temp : -43.4C

Scene Type : IRREGULAR CDO

Subtropical Adjustment : OFF

Extratropical Adjustment : OFF

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : WEST PACIFIC
Dvorak CI > MSLP Conversion Used : CKZ Method

Tno/CI Rules : Constraint Limits : 0.5T/hour
Weakening Flag : ON
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 71km
- Environmental MSLP : 1007mb

Satellite Name : HIM-8
Satellite Viewing Angle : 27.6 degrees

****************************************************

[euro6208]

Common sense.

19W LEEPI 180812 1200 23.7N 141.8E WPAC 65 974

7th TY of the season...

[euro6208]

19W LEEPI 180812 1200 23.6N 141.7E WPAC 65 983

CP down more...

[euro6208]

WDPN31 PGTW 122100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (LEEPI) WARNING NR 08//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 19W (LEEPI), LOCATED APPROXIMATELY 37 NM
WEST-SOUTHWEST OF IWO TO, JAPAN, HAS TRACKED NORTHWESTWARD AT 11
KNOTS OVER THE PAST SIX HOURS. ANIMATED EIR SATELLITE IMAGERY DEPICTS
A MIDGET SYSTEM (APPROXIMATELY 60 NM ACROSS) WITH A VERY COMPACT
EYEWALL. THE 121800Z 140/25G39 KNOTS WIND OBSERVATION FROM IWO-TO, 35
NM TO THE NORTHEAST, HIGHLIGHTS HOW DIMINUTIVE THIS SYSTEM IS. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A
CLOUD-FILLED PINHOLE EYE IN THE EIR LOOP WITH HIGH CONFIDENCE. THE
INITIAL INTENSITY OF 65 KNOTS IS BASED ON A DVORAK ESTIMATE OF T4.0
FROM PGTW. UPPER LEVEL CONDITIONS REMAIN CONDITIONALLY FAVORABLE WITH
LOW VWS AND ENHANCED POLEWARD OUTFLOW INTO A TUTT CELL TO THE
NORTHEAST. HOWEVER, THIS OUTFLOW CHANNEL APPEARS TO BE GRADUALLY
WEAKENING DUE TO INCREASING CONVERGENT FLOW OVER THE NORTHERN
PERIPHERY OF THE SYSTEM AS EVIDENT IN ANIMATED WATER VAPOR IMAGERY.
TY 19W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) POSITIONED EAST AND NORTHEAST OF THE SYSTEM.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TY LEEPI IS FORECAST TO TRACK NORTHWESTWARD ALONG THE WESTERN
PERIPHERY OF THE STR POSITIONED TO THE EAST THROUGH TAU 36 THEN WEST-
NORTHWESTWARD THROUGH TAU 72 AS IT TRANSITIONS TO THE STEERING
INFLUENCE OF THE STR OVER WESTERN JAPAN. TY 19W IS EXPECTED TO
MAINTAIN INTENSITY OF 65 KNOTS THROUGH TAU 12 WITH SOME UNCERTAINTY
IN THE EXACT PEAK DUE TO THE COMPACT NATURE OF THE SYSTEM. AS THE
SYSTEM TRACKS FURTHER NORTHWEST, VWS WILL INCREASE TO MODERATE TO
STRONG LEVELS (20-30 KNOTS), GRADUALLY WEAKENING THE SYSTEM. TY 19W
WILL CONCURRENTLY BECOME EMBEDDED WITHIN THE NORTHERN PERIPHERY OF A
BROAD LOW PRESSURE AREA EAST OF TAIWAN AFTER TAU 48. CONSEQUENTLY, TY
19W SHOULD DISSIPATE BY TAU 72. WITH THE EXCEPTION OF NAVGEM AND
COAMPS-TC, WHICH RECURVE THE SYSTEM ERRONEOUSLY INTO THE STR,
NUMERICAL MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH TAU 72,
THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

TPPN13 PGTW 122138

A. TYPHOON 19W (LEEPI)

B. 12/2100Z

C. 25.10N

D. 140.23E

E. FIVE/HMWRI8

F. T4.0/4.0/D1.0/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 46A/PBO EMBD CNTR/ANMTN. LLCC EMBEDDED IN MG YIELDS
A DT OF 4.0. MET AND PT AGREE. DBO DT.

I. ADDITIONAL POSITIONS: NONE


LOWE

[euro6208]

TXPQ21 KNES 122107
TCSWNP

A. 19W (LEEPI)

B. 12/2030Z

C. 25.3N

D. 140.5E

E. THREE/HIMAWARI-8

F. T3.5/4.0/S0.0/24HRS

G. IR/EIR/SWIR/AMSR2

H. REMARKS...THIS INTENSITY ESTIMATE WAS DERIVED USING 4 KM IR
DATA. SYSTEM CHARACTERIZED BY LLCC EMBEDDED IN DG FOR A DT=4.0 MET=3.5
PT=3.5 FT IS BASED ON MET DUE TO LOW CONFIDENCE IN CENTER FIX LOCATION.

I. ADDL POSITIONS

12/1612Z 24.1N 141.3E AMSR2


...FISHER

[euro6208]

[euro6208]

Once again upgraded to a typhoon.

WDPN31 PGTW 130900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (LEEPI) WARNING NR
10//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON 19W (LEEPI), LOCATED APPROXIMATELY 609 NM SOUTHEAST OF
SASEBO, JAPAN, HAS TRACKED NORTHWESTWARD AT 12 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
CONTINUES TO DEPICT A MIDGET SYSTEM, APPROXIMATELY 90-100NM
DIAMETER, WITH A PERSISTENT CENTRAL DENSE OVERCAST FEATURE. A
130521Z SSMI 85GHZ IMAGE INDICATES A MICROWAVE EYE FEATURE WITH SOME
DEGRADATION TO THE EYEWALL STRUCTURE, SPECIFICALLY BREAKS IN THE
EAST AND WEST QUADRANTS. OVERALL, THERE IS GOOD CONFIDENCE IN THE
INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 65 KNOTS
BASED ON DVORAK INTENSITY ESTIMATES OF T4.0 FROM KNES AND PGTW.
ADDITIONALLY, A 130003Z ASCAT IMAGE SHOWS A 60-KNOT WIND BARB OVER
THE NORTHEAST QUADRANT. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE
ENVIRONMENT WITH LOW VERTICAL WIND SHEAR AND GOOD POLEWARD OUTFLOW,
ENHANCED BY THE TUTT CELL TO THE EAST AND A DEVELOPING UPPER LOW
SOUTH OF TOKYO. TY 19W IS TRACKING NORTHWESTWARD UNDER THE STEERING
INFLUENCE OF THE SUBTROPICAL RIDGE (STR) TO THE EAST AND
NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TY 19W IS FORECAST TO TRACK NORTHWESTWARD THROUGH TAU 24 THEN
WEST-NORTHWESTWARD TO WESTWARD THROUGH TAU 72 AS IT TRANSITIONS TO
THE STEERING INFLUENCE OF THE STR POSITIONED OVER WESTERN JAPAN. TY
19W IS EXPECTED TO WEAKEN STEADILY THROUGH THE FORECAST PERIOD DUE
TO INCREASING NORTHERLY TO NORTHEASTERLY FLOW AND MODERATE LEVELS OF
VERTICAL WIND SHEAR. ADDITIONALLY, TY 19W WILL BECOME EMBEDDED
WITHIN THE NORTHERN PERIPHERY OF A BROAD SYSTEM FORECAST TO
DEVELOP EAST OF TAIWAN AFTER TAU 24. CONSEQUENTLY, TY 19W SHOULD
DISSIPATE BY TAU 72 DUE TO THE OVERALL MARGINAL CONDITIONS. WITH THE
EXCEPTION OF HWRF, WHICH ERRONEOUSLY RECURVES THE SYSTEM THROUGH THE
STR, NUMERICAL MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH TAU
72, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

50 knots

WDPN31 PGTW 132100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (LEEPI) WARNING NR
12//
RMKS//
TROPICAL STORM (TS) 19W (LEEPI), LOCATED APPROXIMATELY 443 NM
SOUTHEAST OF IWAKUNI, JAPAN, HAS TRACKED NORTHWESTWARD AT 11 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS AN INCREASINGLY DISORGANIZED AND WEAKENING SYSTEM
WITH DEEP CONVECTION SHOWING SIGNS OF BECOMING ELONGATED AND
SHEARED. A 131638Z ATMS 89 GHZ MICROWAVE IMAGE CONFIRMS THE OVERALL
ASSESSMENT, WITH MINIMAL DEEP CONVECTION STRETCHED OUT FROM THE
CENTER TOWARDS THE SOUTHEAST, AND SHALLOW BANDING INTO THE LLCC IN
ALL BUT THE NORTHEASTERN SEMICIRCLE. THE INITIAL POSITION IS PLACED
WITH LOW CONFIDENCE BASED IN LARGE PART ON THE AFOREMENTIONED
MICROWAVE IMAGERY DUE TO THE LACK OF ANY VISIBLE LLCC IN THE
INFRARED IMAGERY. THE INITIAL INTENSITY IS ASSESSED AT A GENEROUS 50
KNOTS, HEDGED SLIGHTLY LOWER THAN DVORAK CURRENT INTENSITY ESTIMATES
OF T3.5 (55 KNOTS) FROM KNES AND PGTW, CONSISTENT WITH A SATCON
ESTIMATE OF 52 KNOTS AND AUTOMATED DVORAK ESTIMATES OF 43 KNOTS.
ENVIRONMENTAL ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT
WITH LOW VWS AND MODERATE EASTWARD OUTFLOW INTO A VERY NARROW
CHANNEL EXTENDING INTO A STRONG TUTT CELL TO THE EAST. HOWEVER,
UPPER LEVEL NORTHEASTERLY FLOW IS BEGINNING TO IMPINGE ON THE
SYSTEMS WESTERN AND NORTHERN PERIPHERY, CONTRIBUTING TO THE OVERALL
WEAKENING TREND. TS 19W CONTINUES TRACKING NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE SUBTROPICAL RIDGE (STR) TO THE EAST AND
NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS PROGNOSTIC REASONING BULLETIN.
B. TS 19W IS FORECAST TO TRACK NORTHWESTWARD THROUGH TAU 12 THEN
WEST-NORTHWESTWARD TO WESTWARD THROUGH TAU 48 UNDER THE STEERING
INFLUENCE OF THE STR POSITIONED OVER JAPAN, MAKING LANDFALL ALONG
THE EXTREME SOUTHERN TIP OF KYUSHU NEAR TAU 36. AFTER THIS POINT
AND THROUGH THE END OF THE FORECAST, TS 19W IS FORECAST TO TURN
SHARPLY WEST AND THEN SOUTH, AS IT COMES UNDER THE INFLUENCE OF,
AND EVENTUALLY BECOMES ABSORBED INTO, INVEST AREA 98W. TS LEEPI IS
EXPECTED TO STEADILY WEAKEN THROUGH THE FORECAST PERIOD DUE TO
INCREASING NORTHEASTERLY CONVERGENT FLOW AND INCREASING VWS,
DISSIPATING BY TAU 72 AS IT BECOMES ABSORBED INTO THE NORTHEASTERLY
PERIPHERY OF INVEST 98W. NUMERICAL MODEL GUIDANCE REMAINS IN GOOD
AGREEMENT THROUGH TAU 24 BUT THEREAFTER PRESENTS A BIFURCATION
SCENARIO. THE GFS, COTC AND JGSM MODELS SUPPORT THE CURRENT
FORECAST, DEPICTING A TURN TOWARDS THE SOUTH, THOUGH VARYING IN THE
SHARPNESS OF THE TURN, THE EGRR, ECMWF AND HWRF DEPICT AN ALTERNATE
SCENARIO, PULLING TS 19W NORTHEASTWARD AHEAD OF AN APPROACHING DEEP
MID-LATITUDE TROUGH. SEVERAL OTHER TRACKERS LOSE THE VORTEX BY TAU
48, INDICATING DISSIPATION BEFORE INTERACTION WITH 98W AND THE TURN
SOUTH. THE OFFICIAL TRACK LIES SOUTH OF THE MULTI-MODEL CONSENSUS
THROUGH TAU 48, THEN COMES MORE IN LINE WITH THE GFS SOLUTION
TRACKING THE SYSTEM TOWARDS THE SOUTH. DUE TO THE HIGH UNCERTAINTY
IN THE INTENSITY FORECAST BEYOND TAU 48, AND THE ATTENDANT
UNCERTAINTY IN THE TRACK, THERE LOW CONFIDENCE IN THE JTWC FORECAST
TRACK.//
NNNN

[euro6208]

Back up to 60 knots.

WDPN31 PGTW 140300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (LEEPI) WARNING NR
13//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 19W (LEEPI), LOCATED APPROXIMATELY 363 NM
SOUTHEAST OF IWAKUNI, JAPAN, HAS TRACKED NORTHWESTWARD AT 14 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTI-SPECTRAL SATELLITE IMAGERY
DEPICTS A COMPACT SYSTEM WITH TIGHTLY CURVED BANDING WRAPPING INTO A
DEFINED LOW LEVEL CIRCULATION CENTER. A 132316Z GPM 37 GHZ MICROWAVE
IMAGE REVEALS A WELL-DEFINED LOW LEVEL MICROWAVE EYE, HOWEVER, THE
VORTEX IS MUCH MORE POORLY DEFINED IN THE 89 GHZ CHANNEL. THE INITIAL
POSITION IS BASED ON THE GMI MICROWAVE EYE WITH GOOD CONFIDENCE. THE
INITIAL INTENSITY IS ASSESSED AT 60 KNOTS, BASED ON THE PGTW DVORAK
ESTIMATE OF T4.0 (65 KNOTS) AND ROUNDED DOWN SLIGHTLY GIVEN AUTOMATED
FIXES, SCATTEROMETRY DATA, AND THE DEEP LEVEL VORTEX STRUCTURE WHICH
DON'T SUPPORT TYPHOON INTENSITY. ENVIRONMENTAL ANALYSIS INDICATES A
MARGINALLY FAVORABLE ENVIRONMENT WITH LOW VWS AND MODERATE EASTWARD
OUTFLOW INTO A VERY NARROW CHANNEL EXTENDING INTO A STRONG TUTT CELL
TO THE EAST. TS 19W CONTINUES TRACKING NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE SUBTROPICAL RIDGE (STR) TO THE EAST AND
NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS PROGNOSTIC REASONING BULLETIN, HOWEVER, THE TRACK HAS BEEN
SHIFTED NORTHWARD BASED ON THE LATEST AVAILABLE ANALYSIS OF TRACK
MOTION.
B. TS 19W IS FORECAST TO CONTINUE TRACKING GENERALLY NORTHWESTWARD
THROUGH TAU 36 WHEN A PASSING MID-LATITUDE TROUGH DISRUPTS THE
STEERING FLOW AND BRINGS HIGH VALUES OF VERTICAL WIND SHEAR (VWS).
THE POSITIVE TILT OF THE TROUGH AXIS SUGGESTS THAT RE-CURVATURE IS
UNLIKELY. INSTEAD, THE LLCC IS EXPECTED TO SLOW SIGNIFICANTLY AND
WEAKEN DUE TO THE VWS AND LOWER SST VALUES. THE WEAKENED SYSTEM WILL
THEN DEFLECT TO THE SOUTHWEST UNDER THE LOW LEVEL STEERING FLOW AND
DISSIPATE OVER WATER. IT IS POSSIBLE THAT THE REMNANT CIRCULATION MAY
INTERACT WITH INVEST 98W TO THE SOUTH. THE AVAILABLE ENSEMBLE
GUIDANCE IS BI-FURCATED BETWEEN THE RE-CURVE AND SOUTHWESTERLY TRACK
SCENARIOS. DUE TO THE HIGH UNCERTAINTY BEYOND THE TAU 36 BI-FURCATION
POINT, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN

[mrbagyo]