WPAC: LUPIT - Post-Tropical

[1900hurricane]

A very sloppy Western Pacific has yielded a new invest. A breakdown/reshuffling in the mid-latitude NPac blocking regime has allowed a prominent Mei-yu setup to kick out, leaving an old front/string of low level vorticity stretched out SW to NE across the subtropical WPac. At the SW end of this low level trough, around 24*N, 148*E, invest 94W has been tagged where vorticity appears to be slowly consolidating.







The overall setup remains very convoluted, and I am very unsure if 94W is going to find any space to develop. The invest lies sandwiched in a break in subtropical ridging with the TUTT to the SW and a mid-latitude trough beginning to cut off to the north. The invest is currently sitting in a zone of low shear, but is not far removed from belts of significant shear from both the TUTT and mid-latitude trough. Regardless of development, 94W should begin to feel the weakness induced by the trough beginning to cut off to the north and enter the flow around it, moving off to the NE and then N into the mid-latitudes in a few days.

[1900hurricane]

Not going to lie, I'm having a tougher than usual time wrapping my head around this setup.

[euro6208]

Interesting discussion about this subtropical. Remains me of the Atlantic.

AN AREA OF CONVECTION HAS PERSISTED NEAR 24.5N 149.0E,
APPROXIMATELY 420 NM EAST OF IWO TO. RECENT ANIMATED MULTISPECTRAL
SATELLITE IMAGERY SHOWS SCATTERED DEEP CONVECTION DEVELOPING OVER AN
ELONGATED LOW LEVEL CIRCULATION CENTER EVIDENT IN A 212330Z ASCAT
PASS. THIS DISTURBANCE LIES IN AN AREA OF MODERATE VERTICAL WIND
SHEAR AND MULTIDIRECTIONAL OUTFLOW ALOFT. ENVIRONMENTAL ANALYSIS
INDICATES THAT THE CIRCULATION HAS DEVELOPED AT THE TAIL END OF A
MID-LATITUDE TROUGH, AND IT IS CURRENTLY ASSESSED AS SUBTROPICAL.
SEA SURFACE TEMPERATURES AND UPPER-LEVEL CONDITIONS ARE SUFFICIENT
TO SUPPORT TRANSITION INTO A TROPICAL CYCLONE OVER THE NEXT FEW
DAYS, BUT THE CIRCULATION IS EXPECTED TO TRACK INTO THE MID-LATITUDE
FLOW PATTERN DURING THE SAME PERIOD. TRANSITION INTO A TROPICAL
STRUCTURE IS NOT EXPECTED TO OCCUR WITHIN THE NEXT 24 HOURS.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. BECAUSE
THE DISTURBANCE WILL LIKELY REMAIN SUBTROPICAL FOR THE NEXT DAY, THE
POTENTIAL FOR DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN
THE NEXT 24 HOURS IS LOW.

[1900hurricane]

Meh, I don't think it's organized enough yet to really differentiate between tropical or subtropical. For one, the circulation is still elongated along the vorticity axis if formed along. It does appear to be gaining some sovereignty though.

[1900hurricane]

JMA has classified 94W as a Tropical Depression on their surface analysis.

[euro6208]

TXPQ21 KNES 222128
TCSWNP

A. TROPICAL DISTURBANCE (94W)

B. 22/2030Z

C. 24.8N

D. 152.3E

E. FIVE/HIMAWARI-8

F. T1.0/1.0/D1.0/24HRS

G. IR/EIR/VIS

H. REMARKS...MOST RECENT MICROWAVE DATA AND ANIMATED VISIBLE IMAGERY ARE
AMBIGUOUS AS TO THE EXISTENCE OF A CLOSED LOW LEVEL CIRCULATION. THEREFORE
POSITION IS BASED ON MID LEVEL CENTER. BANDING OF 4/10 RESULTS IN A
DT=2.5. MET=1.0 PT=1.0 FT IS BASED ON CONSTRAINTS LIMITING INITIAL
CLASSIFICATION TO T1.0/1.0.

I. ADDL POSITIONS

NIL


...FISHER

[euro6208]

TXPQ21 KNES 230318
TCSWNP

A. TROPICAL DISTURBANCE (94W)

B. 23/0230Z

C. 25.6N

D. 152.9E

E. THREE/HIMAWARI-8

F. T2.0/2.0/D1.0/24HRS

G. IR/EIR/VIS

H. REMARKS...CENTER FIX LOCATION BASED ON MID-LEVEL. CURVED BANDING OF
0.4 YIELDS A DT OF 2.5. MET=1.0 AND PT=1.5. FT IS BASED ON CONSTRAINTS
LIMITING THE MAXIMUM INCREAST IN FT BY 1.0 OVER 6 HOURS.

I. ADDL POSITIONS

NIL


...VELASCO

[euro6208]

THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 24.5N
149.0E, IS NOW LOCATED NEAR 25.6N 152.5E, APPROXIMATELY 610 NM EAST
OF IWO TO, JAPAN. RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY
AND ALL AVAILABLE MICROWAVE IMAGERY SHOW SCATTERED DEEP CONVECTION
AND CONVECTIVE BANDING DEVELOPING OVER THE SOUTHEASTERN AND SOUTHERN
PERIPHERY OF AN ELONGATED LOW LEVEL CIRCULATION CENTER (LLCC)
EVIDENT IN A 230003Z METOP-B ASCAT PASS. HIGHEST WIND SPEEDS ARE
ALONG THE SOUTHEAST QUADRANT IS 25 TO 30 KNOTS. THIS DISTURBANCE
LIES IN AN AREA OF MODERATE (10 TO 20 KNOTS) VERTICAL WIND SHEAR AND
MULTI-DIRECTIONAL OUTFLOW ALOFT. RECENT AMSU TEMPERATURE ANOMALY
PRODUCTS INDICATE A WARMING TREND IN THE MID-LEVEL STRUCTURE.
ENVIRONMENTAL ANALYSIS INDICATES THAT THE CIRCULATION HAS DEVELOPED
AT THE TAIL END OF A MID-LATITUDE TROUGH AND IS CURRENTLY ASSESSED
AS SUBTROPICAL IN NATURE. SEA SURFACE TEMPERATURES AND UPPER-LEVEL
CONDITIONS ARE SUFFICIENT TO SUPPORT TRANSITION INTO A TROPICAL
CYCLONE OVER THE NEXT FEW DAYS, BUT THE CIRCULATION IS EXPECTED TO
TRACK INTO THE MID-LATITUDE FLOW DURING THE SAME PERIOD. TRANSITION
INTO A TROPICAL STRUCTURE IS NOT EXPECTED TO OCCUR WITHIN THE NEXT
24 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB.
BASED ON RECENT CONDITIONS AND ASSESSED DATA, THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS UPGRADED TO MEDIUM.

[cycloneye]

JTWC upgrades to Tropical Storm 04W.

[NotoSans]

Upgraded to TS Lupit.

TS 1602 (Lupit)
Issued at 19:05 UTC, 23 July 2016

<Analysis at 18 UTC, 23 July>
Scale -
Intensity -
Center position N28°30' (28.5°)
E156°50' (156.8°)
Direction and speed of movement NE 30 km/h (15 kt)
Central pressure 1000 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 190 km (100 NM)
NW 90 km (50 NM)

<Forecast for 06 UTC, 24 July>
Intensity -
Center position of probability circle N32°30' (32.5°)
E158°20' (158.3°)
Direction and speed of movement NNE 40 km/h (21 kt)
Central pressure 1000 hPa
Maximum wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 70 km (40 NM)

<Forecast for 18 UTC, 24 July>
Intensity -
Center position of probability circle N37°20' (37.3°)
E158°50' (158.8°)
Direction and speed of movement N 45 km/h (24 kt)
Central pressure 1000 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 18 UTC, 25 July>
Intensity -
LOW
Center position of probability circle N45°00' (45.0°)
E154°25' (154.4°)
Direction and speed of movement NNW 40 km/h (21 kt)
Central pressure 1004 hPa
Maximum sustained wind speed 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 200 km (110 NM)

[euro6208]

JTWC upgrades to Tropical Storm 04W.

Straight to a TS but looks to be very short lived.

[euro6208]

WDPN31 PGTW 232100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W (FOUR) WARNING NR
02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 04W (FOUR), LOCATED APPROXIMATELY 309 NM
NORTH-NORTHEAST OF MINAMI TORI SHIMA, HAS TRACKED NORTHEASTWARD AT
17 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY DEPICTS THE RAGGED CENTRAL DEEP CONVECTION OF A
HYBRID (TROPICAL/SUB-TROPICAL) CYCLONE, WITH INCREASING FRONTAL
CHARACTERISTICS. A CIRA AMSU CROSS SECTION STILL INDICATES THE
PRESENCE OF A WEAK UPPER LEVEL WARM CORE. UPPER LEVEL ANALYSIS
INDICATES TS 04W IS WEDGED IN A NARROW ZONE BETWEEN TWO UPPER LEVEL
LOWS, AND NORTH OF THE SUBTROPICAL RIDGE AXIS. VERTICAL WIND SHEAR
(VWS) IN THIS ZONE INCREASES SHARPLY TO THE NORTH, AND IS CURRENTLY
30 KNOTS OVER THE SYSTEM. A 231816Z SSMIS 37 GHZ IMAGE DEPICTS THE
COMPACT AREA OF DEEP CONVECTION AND THE NOTED FRONTAL FEATURE. THE
INITIAL POSITION WAS BASED ON THE EIR ANIMATION AND GENERALLY
SUPPORTED BY THE AFOREMENTIONED SSMIS PASS. THE INITIAL INTENSITY IS
ASSESSED AT 35 KNOTS, BASED ON THE PGTW DVORAK ESTIMATE OF 30 KNOTS,
AND TAKING INTO ACCOUNT AN EARLIER ASCAT PASS WITH 35 KNOT WINDS. TS
04W IS CURRENTLY TRACKING NORTH-NORTHEASTWARD ALONG THE PERIPHERY OF
A SUBTROPICAL RIDGE POSITIONED TO THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. 04W IS EXPECTED TO TURN NORTHWARD AND THEN NORTHWESTWARD AS
THE STEERING RIDGE BUILDS AND RE-ORIENTS, PREVENTING A RECURVATURE.
THE CYCLONE IS CURRENTLY BECOMING EXTRATROPICAL, AND SHOULD COMPLETE
EXTRATROPICAL TRANSITION OVER THE NEXT 24 HOURS. DYNAMIC MODEL
GUIDANCE IS IN VERY TIGHT AGREEMENT THROUGH THE FORECAST PERIOD
GIVING HIGH CONFIDENCE TO THE FORECAST TRACK.//
NNNN

[euro6208]

WDPN31 PGTW 240300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W (LUPIT) WARNING NR
03//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 04W (LUPIT), LOCATED APPROXIMATELY 455 NM
NORTH-NORTHEAST OF MINAMI TORI SHIMA, HAS TRACKED NORTHEASTWARD AT
23 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) INDICATES THAT CENTRAL DEEP CONVECTION OF THIS HYBRID
(TROPICAL/SUB-TROPICAL) CYCLONE HAS RE-CONSOLIDATED OVER THE PAST
SIX HOURS, WHILE ASSOCIATED FRONTAL CHARACTERISTICS AND
STRATOCUMULUS CLOUDS ARE ALSO EVIDENT. THE LAST AVAILABLE CIRA AMSU
CROSS SECTION AT 231900Z STILL INDICATED THE PRESENCE OF A WEAK
UPPER LEVEL WARM CORE. A 232340Z AMSU 89 GHZ IMAGE REVEALS THE
COMPACT AREA OF DEEP CONVECTION OVER THE LOW LEVEL CIRCULATION
CENTER, AND SUPPORTS THE INITIAL POSITION. THE CORRESPONDING ASCAT
IMAGE INDICATES 40 KNOTS WINDS ALONG THE EASTERN SEMI-CIRCLE. THE
INITIAL POSITION IS BASED ON THE MSI ANIMATION AND NOTED AMSU
IMAGERY WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT
40 KNOTS, WHICH IS SLIGHTLY HIGHER THAN AGENCY ESTIMATES BASED ON
THE NOTED ASCAT DATA. UPPER LEVEL ANALYSIS INDICATES TS 04W IS
WEDGED IN A NARROW ZONE BETWEEN TWO UPPER LEVEL LOWS, AND NORTH OF
THE SUBTROPICAL RIDGE AXIS. THE GRADIENT OF VERTICAL WIND SHEAR
(VWS) IN THIS ZONE INCREASES SHARPLY TO THE NORTH, AND VWS IS
ALREADY HIGH (40 KNOTS) OVER THE SYSTEM. LUPIT IS CURRENTLY TRACKING
NORTH-NORTHEASTWARD ALONG THE PERIPHERY OF A SUBTROPICAL RIDGE
POSITIONED TO THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 04W IS EXPECTED TO TURN NORTHWARD AND THEN NORTHWESTWARD AS
THE STEERING RIDGE BUILDS TO THE EAST AND RE-ORIENTS AHEAD OF THE
CURRENT STORM MOTION, CAUSING THE WESTWARD TURN. BY TAU 24, VWS IS
EXPECTED TO BE OVER 50 KNOTS, AND SEA SURFACE TEMPERATURES WILL DROP
TO BETWEEN 24 TO 25 DEGREES CELSIUS. THE CYCLONE IS CURRENTLY
BECOMING EXTRATROPICAL, AND GIVEN THESE HIGHLY UNFAVORABLE
CONDITIONS SHOULD COMPLETE EXTRATROPICAL TRANSITION INTO A GALE
FORCE LOW OVER THE NEXT 24 HOURS. DYNAMIC MODEL GUIDANCE IS IN VERY
TIGHT AGREEMENT THROUGH THE FORECAST PERIOD GIVING HIGH CONFIDENCE
TO THE FORECAST TRACK.//
NNNN

[1900hurricane]

[1900hurricane]

JTWC is now stating that Lupit has transitioned into an extratropical system.

[supercane]

Still a TS per JMA:
WTPQ20 RJTD 241500
RSMC TROPICAL CYCLONE ADVISORY
NAME TS 1602 LUPIT (1602)
ANALYSIS
PSTN 241500UTC 36.1N 159.4E FAIR
MOVE N 21KT
PRES 1000HPA
MXWD 040KT
GUST 060KT
30KT 100NM
FORECAST
24HF 251500UTC 45.2N 154.9E 60NM 70% EXTRATROPICAL LOW =

[cycloneye]

Last warning issued by JMA.

LOW
Issued at 18:45 UTC, 24 July 2016


<Analysis at 18 UTC, 24 July>
Scale -
Intensity -
LOW
Center position N37°00' (37.0°)
E159°00' (159.0°)
Direction and speed of movement N 45 km/h (25 kt)
Central pressure 1000 hPa