WPAC: KUJIRA - Post-Tropical

[Hayabusa]

97W.INVEST

97W INVEST 200924 1800 20.0N 160.0E WPAC 15 0

[Hayabusa]

[mrbagyo]

97W INVEST 200925 1200 19.0N 157.1E WPAC 15 1010

idk if 97W is still alive or the area of deep convection near 17.5N, 162E just looks more promising
it's either JTWC reposition or they tag a new invest

[euro6208]

AN AREA OF CONVECTION (INVEST 97W) HAS PERSISTED NEAR
18.8N 158.2E, APPROXIMATELY 848 NM EAST-NORTHEAST OF GUAM. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY DEPICTS A VERY BROAD, ASYMMETRIC LOW
LEVEL CIRCULATION (LLC) WITH A LARGE AREA OF FLARING DEEP CONVECTION
TO THE SOUTH. THIS IS REFLECTED IN A 252028Z SSMIS 91GHZ MICROWAVE
IMAGE, REVEALING A DISTINCT LACK OF CONVECTION OVER THE LLC AND
FRAGMENTED DEEP CONVECTION RELEGATED TO THE SOUTHERN PERIPHERY. A
252252Z METOP-B ASCAT PASS SHOWS A CONFUSED, WEAK WIND FIELD WITH NO
DISTINCT CIRCULATION AND A LARGE SWATH OF 15 TO 20 KNOT WINDS
EXTENDING TO THE NORTH-EAST. 97W IS CURRENTLY EXPERIENCING A
FAVORABLE ENVIRONMENT WITH EXCELLENT EQUATORWARD OUTFLOW, LOW (5 TO
10 KNOT) VERTICAL WIND SHEAR, AND WARM (30 TO 31 CELSIUS) SEA
SURFACE TEMPERATURES. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 97W
WILL TRACK GENERALLY NORTHWARD WHILE INTENSIFYING. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1010 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS LOW.

[Hayabusa]

WWJP27 RJTD 260000
WARNING AND SUMMARY 260000.
WARNING VALID 270000.
WARNING IS UPDATED EVERY 6 HOURS.
LOW PRESSURE AREA 1010 HPA NEAR 18N 157E ALMOST STATIONARY.

[euro6208]

Quite a difference in the models. EURO peaks this at 995 mb while GFS peaks it at 956 mb!

[Hayabusa]

Quite a difference in the models. EURO peaks this at 995 mb while GFS peaks it at 956 mb!

If you mean the graphic, the 995 mb is the control run (low resolution), look at HRES run (high resolution/operational) it's 989 mb but still a difference from the GFS

[NotoSans]

JMA expects this to become a tropical storm within 24 hours.

[euro6208]

Up to Medium

THE AREA OF CONVECTION (INVEST 97W) PREVIOUSLY LOCATED
NEAR 18.8N 158.2E IS NOW LOCATED NEAR 18.9N 160.2E, APPROXIMATELY
365 NM WEST OF WAKE ISLAND. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A CONSOLIDATING LOW LEVEL CIRCULATION (LLC) WITH FLARING
CONVECTION IN THE SOUTHWESTERN SEMICIRCLE. A 260248Z 88.2GHZ ATMS
IMAGE REVEALS FORMATIVE BANDING WRAPPING INTO THE LLC. UPPER LEVEL
ANALYSIS REVEALS A MARGINALLY FAVORABLE ENVIRONMENT WITH A POINT
SOURCE OVER THE SYSTEM CENTER ENHANCING UPPER LEVEL DIFFLUENCE
OFFSET BY AN UPPER LEVEL LOW HINDERING CONVECTION OVER THE
NORTHWESTERN SEMICIRCLE. INVEST 97W IS EXPERIENCING LOW (<15KTS)
VERTICAL WIND SHEAR AND WARM (30-31C) SEA SURFACE TEMPERATURES.
GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 97W WILL TRACK GENERALLY
NORTH-NORTHWESTWARD WHILE CONTINUING TO INTENSIFY. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS UPGRADED TO MEDIUM.

[Hayabusa]

WWJP27 RJTD 260600
WARNING AND SUMMARY 260600.
WARNING VALID 270600.
WARNING IS UPDATED EVERY 6 HOURS.
GALE WARNING.
TROPICAL DEPRESSION 1006 HPA
AT 18.0N 160.0E SEA AROUND OF MINAMITORISIMA MOVING NW SLOWLY.
POSITION FAIR.
MAX WINDS 30 KNOTS NEAR CENTER.
EXPECTED MAX WINDS 35 KNOTS NEAR CENTER WITHIN NEXT 24 HOURS.
FORECAST POSITION FOR 270600UTC AT 21.7N 157.5E WITH 80 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.
EXTENDED OUTLOOK.
FORECAST POSITION FOR 280600UTC AT 26.3N 153.2E WITH 130 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.
FORECAST POSITION FOR 290600UTC AT 32.2N 152.5E WITH 200 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.
FORECAST POSITION FOR 300600UTC AT 40.5N 157.8E WITH 280 MILES RADIUS
OF 70 PERCENT PROBABILITY CIRCLE.

[Hayabusa]

TD
Issued at 07:05 UTC, 26 September 2020

<Analysis at 06 UTC, 26 September>
Scale -
Intensity -
TD
Center position N18°00' (18.0°)
E160°00' (160.0°)
Direction and speed of movement NW Slow
Central pressure 1006 hPa
Maximum wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)

<Forecast for 06 UTC, 27 September>
Intensity -
Center position of probability circle N21°40' (21.7°)
E157°30' (157.5°)
Direction and speed of movement NNW 20 km/h (11 kt)
Central pressure 998 hPa
Maximum wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 150 km (80 NM)

<Forecast for 06 UTC, 28 September>
Intensity -
Center position of probability circle N26°20' (26.3°)
E153°10' (153.2°)
Direction and speed of movement NW 30 km/h (15 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 240 km (130 NM)
Storm warning area ALL 300 km (160 NM)

<Forecast for 06 UTC, 29 September>
Intensity -
Center position of probability circle N32°10' (32.2°)
E152°30' (152.5°)
Direction and speed of movement N 30 km/h (15 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 370 km (200 NM)
Storm warning area ALL 450 km (245 NM)

<Forecast for 06 UTC, 30 September>
Intensity -
LOW
Center position of probability circle N40°30' (40.5°)
E157°50' (157.8°)
Direction and speed of movement NNE 45 km/h (23 kt)
Central pressure 986 hPa
Maximum sustained wind speed 25 m/s (50 kt)
Maximum wind gust speed 35 m/s (70 kt)
Radius of probability circle 520 km (280 NM)

[Hayabusa]

WTPN21 PGTW 260900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 97W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
210 NM EITHER SIDE OF A LINE FROM 18.3N 159.7E TO 25.1N 155.8E
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 260600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 19.2N 159.7E. THE SYSTEM IS MOVING NORTHWARD AT 08 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 97W) PREVIOUSLY LOCATED
NEAR 18.9N 160.2E IS NOW LOCATED NEAR 19.2N 159.7E, APPROXIMATELY
391 NM WEST OF WAKE ISLAND. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A BROAD LOW LEVEL CIRCULATION (LLC) WITH PERSISTENT
CONVECTION IN THE SOUTHERN AND EASTERN SEMICIRCLES. A 260742Z SSMIS
91GHZ IMAGE REVEALS FORMATIVE BANDING IN THE SOUTHERN QUADRANT
WRAPPING INTO THE EASTERN QUADRANT OF THE LLC. UPPER LEVEL ANALYSIS
REVEALS A MARGINALLY FAVORABLE ENVIRONMENT WITH A POINT SOURCE OVER
THE SYSTEM CENTER ENHANCING UPPER LEVEL DIFFLUENCE OFFSET BY AN
UPPER LEVEL LOW HINDERING CONVECTION OVER THE NORTHWESTERN
SEMICIRCLE. INVEST 97W IS EXPERIENCING LOW (<15KTS) VERTICAL WIND
SHEAR AND WARM (30-31C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE
IN GOOD AGREEMENT THAT 97W WILL TRACK GENERALLY NORTH-NORTHWESTWARD
WHILE CONTINUING TO SLOWLY CONSOLIDATE; HOWEVER, THE UPPER LEVEL LOW
MAY HINDER CONVECTIVE DEVELOPMENT OVER THE WESTERN SEMICIRCLE.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 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
270900Z.//
NNNN

[euro6208]

Hoping for more rain!

[euro6208]

06Z GFS peak 948 mb.

[mrbagyo]

97W INVEST 200926 1200 19.2N 160.2E WPAC 20 1006

[Hayabusa]

950 mb peak forecast that's still a TD, well that's a first but then this is just the new TD warning with TS expectations. I expect this current minimum pressure (or max wind) forecast for a TC that's still a TD to be easily beaten in the future.

TD
Issued at 16:05 UTC, 26 September 2020

<Analysis at 15 UTC, 26 September>
Scale -
Intensity -
TD
Center position N19°05' (19.1°)
E159°50' (159.8°)
Direction and speed of movement NW 10 km/h (6 kt)
Central pressure 1004 hPa
Maximum wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)

<Forecast for 15 UTC, 27 September>
Intensity -
Center position of probability circle N23°40' (23.7°)
E156°05' (156.1°)
Direction and speed of movement NW 25 km/h (14 kt)
Central pressure 990 hPa
Maximum wind speed near center 23 m/s (45 kt)
Maximum wind gust speed 35 m/s (65 kt)
Radius of probability circle 150 km (80 NM)

<Forecast for 12 UTC, 28 September>
Intensity -
Center position of probability circle N27°20' (27.3°)
E152°40' (152.7°)
Direction and speed of movement NW 25 km/h (14 kt)
Central pressure 975 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 E 280 km (150 NM)
W 220 km (120 NM)

<Forecast for 12 UTC, 29 September>
Intensity -
Center position of probability circle N33°50' (33.8°)
E153°20' (153.3°)
Direction and speed of movement N 30 km/h (16 kt)
Central pressure 950 hPa
Maximum wind speed near center 40 m/s (80 kt)
Maximum wind gust speed 60 m/s (115 kt)
Radius of probability circle 260 km (140 NM)
Storm warning area E 460 km (250 NM)
W 360 km (195 NM)

<Forecast for 12 UTC, 30 September>
Intensity -
LOW
Center position of probability circle N41°50' (41.8°)
E161°50' (161.8°)
Direction and speed of movement NE 50 km/h (26 kt)
Central pressure 986 hPa
Maximum sustained wind speed 25 m/s (50 kt)
Maximum wind gust speed 35 m/s (70 kt)
Radius of probability circle 370 km (200 NM)

[Hayabusa]

WDPN31 PGTW 262100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (FIFTEEN)
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 15W (FIFTEEN), LOCATED APPROXIMATELY 409
NM WEST OF WAKE ISLAND, HAS TRACKED NORTHWESTWARD AT 11 KNOTS (KTS)
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS A CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC)
WITH PERSISTENT CONVECTION IN THE SOUTHERN AND EASTERN SEMICIRCLES.
OVER THE PAST SIX HOURS, CONVECTION HAS BEGUN TO BUILD OVERHEAD THE
LLCC. A 261757Z SSMIS 91 GHZ MICROWAVE IMAGE REVEALS CONVECTIVE
BANDING WRAPPING INTO THE LLCC FROM THE SOUTH AND THE EAST, LENDING
GOOD CONFIDENCE TO THE INITIAL POSITION. FURTHERMORE, THIS MICROWAVE
IMAGE REVEALS A LACK OF DEEP CONVECTION OVER THE NORTHWESTERN
QUADRANT WHICH IS BEING INHIBITED BY AN UPPER LEVEL LOW POSITIONED
TO THE NORTHWEST. DESPITE THE EFFECTS OF THE UPPER LEVEL LOW, TD 15W
IS IN AN OVERALL MARGINALLY FAVORABLE ENVIRONMENT AS A POINT SOURCE
DIRECTLY OVERHEAD IS ENHANCING UPPER LEVEL DIFFLUENCE. THE INITIAL
INTENSITY IS ASSESSED AT 25 KTS BASED ON MULTI-AGENCY DVORAK CURRENT
INTENSITY ESTIMATES OF T1.5 (25 KTS) BY PGTW, RJTD, AND KNES ALONG
WITH A SWATH OF 25-29 KT WINDS WITHIN THE EASTERN QUADRANT OF THE
SYSTEM OBSERVED IN A 261054Z METOP-C ASCAT IMAGE. TD 15W IS
EXPERIENCING LOW TO MODERATE (15-20 KTS) VERTICAL WIND SHEAR (VWS)
AND WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURES (SST). TD 15W IS
TRACKING NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF A
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE FOR THIS
SYSTEM AND SETS THE FORECAST PHILOSOPHY.
B. TD 15W IS FORECAST TO TRACK NORTH-NORTHWESTWARD THROUGH TAU 36
AS IT STEADILY INTENSIFIES. THE SYSTEM WILL BEGIN TO TURN TO A
GENERALLY NORTHWARD TRACK THROUGH TAU 48 AND THEN RECURVE NORTH-
NORTHEASTWARD THROUGH TAU 72 AS THE SYSTEM ROUNDS THE STR AXIS. THIS
RECURVE IS ENHANCED BY A DEEP MIDLATITUDE TROUGH APPROACHING FROM
THE EAST. THROUGH THE RECURVE, TD 15W SHOULD STEADILY INTENSIFY TO
75 KTS BY TAU 72 DUE TO CONTINUED LOW VWS AND WARM SST. HOWEVER, THE
SYSTEM'S PEAK INTENSITY MAY BE SLIGHTLY HIGHER AND OCCUR PRIOR TO
TAU 72, AROUND TAU 60. INTERACTION WITH THE MIDLATITUDE TROUGH AND
THE BAROCLINIC ZONE WILL CAUSE TD 15W TO BEGIN EXTRATROPICAL
TRANSITION (ETT) BY TAU 72. NUMERICAL MODEL GUIDANCE SHOWS TIGHT
AGREEMENT IN THE NEAR TERM, WITH THE MAXIMUM (123 NM) CROSS-TRACK
SPREAD OCCURRING AT TAU 36 AND THEN DECREASING THROUGH TAU 72.
OVERALL, THERE IS HIGH CONFIDENCE IN THE NEAR TERM JTWC TRACK
FORECAST DUE TO LOW ALONG-TRACK SPREAD AND GOOD AGREEMENT IN THE
TIMING OF THE RECURVE BETWEEN MODEL SOLUTIONS.
C. AFTER TAU 72, INCREASING VERTICAL WIND SHEAR AND COOLING (<26
CELSIUS) SST WILL CAUSE THE SYSTEM TO STEADILY WEAKEN THROUGH THE
REMAINDER OF THE FORECAST PERIOD. TD 15W WILL TURN TO AN EAST-
NORTHEASTWARD TRACK AFTER TAU 72, TRACKING ALONG THE PERIPHERY OF
THE AFOREMENTIONED STR. BY TAU 96, THE SYSTEM WILL WEAKEN TO 45 KTS
AND COMPLETE ETT, GAINING FRONTAL CHARACTERISTICS AS IT BECOMES
EMBEDDED IN THE JET FLOW. NUMERICAL MODEL GUIDANCE IS IN GOOD
AGREEMENT THROUGH THE EXTENDED FORECAST WITH A 100 NM SPREAD AT TAU
72. ADDITIONALLY, THE ECMWF ENSEMBLE SOLUTIONS ARE IN EXCELLENT
AGREEMENT, PLACING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN

[Hayabusa]

13th named storm

TS 2013 (Kujira)
Issued at 01:25 UTC, 27 September 2020

<Analysis at 00 UTC, 27 September>
Scale -
Intensity -
Center position N20°30' (20.5°)
E159°20' (159.3°)
Direction and speed of movement NW 10 km/h (6 kt)
Central pressure 1002 hPa
Maximum wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
≥ 30 kt wind area SE 460 km (250 NM)
NW 185 km (100 NM)

<Forecast for 00 UTC, 28 September>
Intensity -
Center position of probability circle N25°05' (25.1°)
E155°00' (155.0°)
Direction and speed of movement NW 25 km/h (13 kt)
Central pressure 992 hPa
Maximum wind speed near center 23 m/s (45 kt)
Maximum wind gust speed 35 m/s (65 kt)
Radius of probability circle 95 km (50 NM)

<Forecast for 00 UTC, 29 September>
Intensity -
Center position of probability circle N31°10' (31.2°)
E153°50' (153.8°)
Direction and speed of movement N 30 km/h (15 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 E 310 km (170 NM)
W 240 km (130 NM)

<Forecast for 00 UTC, 30 September>
Intensity -
Center position of probability circle N39°00' (39.0°)
E158°10' (158.2°)
Direction and speed of movement NNE 40 km/h (21 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 260 km (140 NM)
Storm warning area E 410 km (220 NM)
W 330 km (180 NM)

<Forecast for 00 UTC, 1 October>
Intensity -
LOW
Center position of probability circle N41°55' (41.9°)
E171°30' (171.5°)
Direction and speed of movement ENE 50 km/h (26 kt)
Central pressure 998 hPa
Maximum sustained wind speed 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 370 km (200 NM)

[euro6208]

WDPN31 PGTW 270300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (FIFTEEN)
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 15W (FIFTEEN), LOCATED APPROXIMATELY 447
NM WEST OF WAKE ISLAND, HAS TRACKED NORTHWESTWARD AT 08 KNOTS (KTS)
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS DEEP CONVECTION OVER THE SOUTHERN AND EASTERN
SEMICIRCLES WITH FORMATIVE BANDING WRAPPING INTO THE CONSOLIDATING LOW
LEVEL CIRCULATION CENTER (LLCC). A 262323Z METOP-C PARTIAL ASCAT IMAGE
REVEALS A SWATH OF 30 KT WINDS WRAPPING AROUND THE EASTERN SEMICIRCLE
OF THE SYSTEM. THE INITIAL POSITION IS PLACED WITH GOOD CONFIDENCE
BASED ON THE ASCAT IMAGE AND A 262229Z MHS 89 GHZ MICROWAVE IMAGE
WHICH SHOWS CONVECTIVE BANDING ALONG THE EASTERN SEMICIRCLE. AN UPPER
LEVEL LOW TO THE NORTHWEST CONTINUES TO HINDER THE DEVELOPMENT OF DEEP
CONVECTION OVER THE NORTHWESTERN QUADRANT AS OBSERVED IN THE MSI. THE
INITIAL INTENSITY IS SET AT 30 KTS, HEDGED SLIGHTLY HIGHER THAN MULTI-
AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T1.5 (25 KTS) AND
SUPPORTED BY A 270001Z ADVANCED DVORAK TECHNIQUE ESTIMATE OF T2.0 (30
KTS) AND THE AFOREMENTIONED ASCAT DATA. TD 15W REMAINS IN A MODERATELY
CONDUCIVE ENVIRONMENT FOR DEVELOPMENT, CHARACTERIZED BY LOW (<15 KT)
VERTICAL WIND SHEAR (VWS) AND WARM (29-30 CELSIUS) SEA SURFACE
TEMPERATURES (SST). THE EFFECTS OF THE UPPER LEVEL LOW ARE BEING
OFFSET BY THE POINT SOURCE LOCATED OVER THE SYSTEM WHICH IS ENHANCING
DIFFLUENCE ALOFT. TD 15W IS TRACKING NORTHWESTWARD UNDER THE STEERING
INFLUENCE OF A SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TD 15W IS FORECAST TO TRACK NORTH-NORTHWESTWARD THROUGH TAU 36
AS IT STEADILY INTENSIFIES DUE TO CONTINUED CONDUCIVE SST AND LOW VWS.
AROUND TAU 36, TD 15W WILL BEGIN TO ROUND THE STR AXIS WITH THE
APPROACH OF A DEEP MIDLATITUDE TROUGH, TURNING FIRST NORTHWARD THROUGH
TAU 48 AND THEN NORTH-NORTHEASTWARD THROUGH TAU 72. NUMERICAL MODEL
GUIDANCE IN IS TIGHT AGREEMENT REGARDING THE TIMING OF THE RECURVE
WITH A CROSS-TRACK SPREAD OF 100 NM AT TAU 36. AFTER TD 15W ROUNDS THE
STR AXIS, IT WILL BEGIN EXTRATROPICAL TRANSITION (ETT) AS IT INTERACTS
WITH THE BAROCLINIC ZONE AROUND TAU 60. THE SYSTEM IS FORECAST TO
INTENSIFY TO A PEAK INTENSITY OF 75 KTS BY TAU 72. HOWEVER, THE
SYSTEM’S PEAK INTENSITY MAY OCCUR EARLIER, AROUND TAU 60. DUE TO THE
LOW MODEL SPREAD, THERE IS GOOD CONFIDENCE IN THE NEAR TERM JTWC TRACK
FORECAST.
C. AFTER TAU 72, INCREASING VERTICAL WIND SHEAR AND RAPIDLY COOLING
(<26 CELSIUS) SST WILL CAUSE THE SYSTEM TO QUICKLY WEAKEN THROUGH THE
REMAINDER OF THE FORECAST PERIOD. TD 15W WILL TURN TO AN EAST-
NORTHEASTWARD TRACK ALONG THE PERIPHERY OF THE AFOREMENTIONED STR. BY
TAU 96, THE SYSTEM WILL GAIN FRONTAL CHARACTERISTICS AS IT COMPLETES
ETT AND BECOMES EMBEDDED IN THE JET FLOW. NUMERICAL MODEL GUIDANCE IS
IN EXCELLENT AGREEMENT THROUGH THE EXTENDED FORECAST WITH A 106 NM
SPREAD AT TAU 72. FURTHERMORE, THE 26/18Z ECMWF ENSEMBLE SOLUTIONS ARE
IN GOOD AGREEMENT THROUGHOUT THE FORECAST PERIOD. THUS, THERE IS
OVERALL HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

Large area of near gale force winds wrapping around the eastern semicircle.