WPAC: Ex 17W - Tropical Depression

[ManilaTC]

A minor TD per JMA WARNING AND SUMMARY 120000.

TROPICAL DEPRESSION 1008 HPA AT 08N 143E ALMOST STATIONARY.

[stormstrike]

THE AREA OF CONVECTION (INVEST 95W) PREVIOUSLY LOCATED NEAR
6.6N 141.3E IS NOW LOCATED NEAR 6.4N 141.6E, APPROXIMATELY 418 NM EAST
OF PALAU. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS AN EXPOSED
AND BROAD LOW-LEVEL CIRCULATION CENTER (LLCC) WITH INTERMITTENT
CONVECTION IN THE WESTERN PERIPHERY. FORMATIVE SHALLOW BANDING IS
OBSERVED WRAPPING INTO THE LLCC IN A 120440Z HIMAWARI-9 VISIBLE 1KM
IMAGE. ANALYSIS INDICATES THAT 95W IS IN A FAVORABLE ENVIRONMENT FOR
DEVELOPMENT WITH EASTERLY DIFFLUENT OUTFLOW ALOFT, LOW VERTICAL WIND
SHEAR (5-10 KTS), AND WARM SEA SURFACE TEMPERATURES (30-31 C). GLOBAL
NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THAT 95W WILL CONTINUE
TO TRACK WESTWARD AS IT CONTINUES TO DEVELOP OVER THE NEXT 24 HOURS.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 22 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 HIGH. SEE REF A (WTPN21 PGTW 120600)
FOR FURTHER DETAILS.

[Hayabusa]

00Z, eps intensity have died down considerably because of 96W

[Hayabusa]

TD a
Issued at 2023/11/12 13:05 UTC
Analysis at 11/12 12 UTC
Grade TD
Scale -
Intensity -
Center position N7°25′ (7.4°)
E140°25′ (140.4°)
Direction and speed of movement NW Slow
Central pressure 1006 hPa
Maximum sustained wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)
Forecast for 11/13 12 UTC
Grade TS
Intensity -
Center position of probability circle N6°50′ (6.8°)
E139°55′ (139.9°)
Direction and speed of movement Almost stationary
Central pressure 1000 hPa
Maximum sustained wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 130 km (70 NM)
Forecast for 11/14 12 UTC
Grade TS
Intensity -
Center position of probability circle N7°00′ (7.0°)
E138°50′ (138.8°)
Direction and speed of movement W Slow
Central pressure 1000 hPa
Maximum sustained wind speed near center 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
Radius of probability circle 200 km (110 NM)
Forecast for 11/15 12 UTC
Grade TS
Intensity -
Center position of probability circle N7°20′ (7.3°)
E137°35′ (137.6°)
Direction and speed of movement W Slow
Central pressure 998 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 260 km (140 NM)
Forecast for 11/16 12 UTC
Grade TS
Intensity -
Center position of probability circle N8°20′ (8.3°)
E135°05′ (135.1°)
Direction and speed of movement WNW 15 km/h (7 kt)
Central pressure 998 hPa
Maximum sustained wind speed near center 20 m/s (40 kt)
Maximum wind gust speed 30 m/s (60 kt)
Radius of probability circle 330 km (180 NM)
Forecast for 11/17 12 UTC
Grade TS
Intensity -
Center position of probability circle N10°35′ (10.6°)
E131°20′ (131.3°)
Direction and speed of movement WNW 20 km/h (11 kt)
Central pressure 994 hPa
Maximum sustained wind speed near center 23 m/s (45 kt)
Maximum wind gust speed 35 m/s (65 kt)
Radius of probability circle 440 km (240 NM)

[Hayabusa]

low intensity forecast

WDPN31 PGTW 121500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 17W (SEVENTEEN)
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 7.2N 140.0E
INITIAL INTENSITY: 25 KTS
GEOGRAPHIC REFERENCE: 178 NM SOUTHEAST OF YAP
MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
SIGNIFICANT WAVE HEIGHT: 11 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY AS WELL AS
ANIMATED PROXY VISIBLE (PROXYVIS) IMAGERY SHOWS FLARING CONVECTION
FIRING ALONG A LINE OF CONVERGENCE TO THE NORTH OF A VERY SMALL LOW
LEVEL CIRCULATION CENTER (LLCC), FORMING A SMALL CENTRAL DENSE
OVERCAST (CDO) TYPE FEATURE. CIRRUS DEBRIS FROM THE CONVECTIVE
ACTIVITY IS OBSCURING THE LLCC, BUT SPIRAL BAND ANALYSIS OF THE
OUTER BANDS IN THE CLEAR AIR TO THE EAST LENT LOW TO MODERATE
CONFIDENCE TO THE INITIAL POSITION. A 120901Z SSMIS 91GHZ MICROWAVE
IMAGE PRESENTED A RATHER DISORGANIZED CIRCULATION, WITH CLEAR
TURNING IN THE MID-LEVEL CONVECTION, BUT ONLY WEAK TURNING EVIDENT
IN THE LOWER LEVELS, WITH A SIGNIFICANT VORTEX TILT WESTWARD WITH
HEIGHT DUE MODERATE EASTERLY SHEAR. THE LLCC IS ASSESSED TO BE
SOMEWHAT ELONGATED ALONG AN EAST-WEST AXIS WITH A PARTIAL 121202Z
ASCAT-B PASS SUGGESTING THE EASTERN EDGE OF THE CIRCULATION COULD
BE AS FAR EAST AS 143E, THOUGH TD 17W IS LOCATED IN THE WESTERN
SIDE OF THE LARGER, ELONGATED ROTATION. THE INITIAL INTENSITY IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AVERAGE OF THE AGENCY
FIXES RANGING BETWEEN T1.0 TO T2.0 AND THE OVERALL STRUCTURAL
IMPROVEMENT. THE SYSTEM SITS IN A SOMEWHAT MARGINAL ENVIRONMENT,
WITH MODERATE EASTERLY DIFFLUENT OUTFLOW ALOFT, LOW DEEP-LAYER
SHEAR BUT MODERATE TO HIGH SHEAR IN THE UPPER-LEVELS AND A FAIR
AMOUNT OF DRY AIR IN THE MID-LEVELS.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: SLOWLY WESTWARD ALONG THE SOUTHERN SIDE
OF A DEEP-LAYER SUBTROPICAL RIDGE TO THE NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T1.5 - 25 KTS
RJTD: T1.0 - 25 KTS
KNES: T2.0 - 30 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
VWS: 10-15 KTS
SST: 30-31 CELSIUS
OUTFLOW: MODERATE WESTWARD
OTHER FACTORS: HIGH UPPER-LEVEL SHEAR, DRY MID-LEVEL AIR.

ANALYSIS CONFIDENCE:
INITIAL POSITION: LOW
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TD 17W (SEVENTEEN) IS EXPECTED TO SLOWLY DRIFT
WESTWARD UNDER THE INFLUENCE OF A GENERALLY WEAK STEERING PATTERN.
PASSAGE OF A LOW- TO MID-LEVEL TROUGH TO THE NORTH HAS RESULTED IN
DEVELOPMENT OF A BREAK IN THE RIDGE DUE NORTH OF THE SYSTEM,
WEAKENING THE STEERING GRADIENT SUCH THAT THE SYSTEM WILL VERY
SLOWLY MOVE TOWARDS THE WEST FOR THE FIRST 48 HOURS OF THE
FORECAST. AFTER TAU 48 THE RIDGE BUILDS IN TO THE NORTH,
STRENGTHENS THE STEERING GRADIENT, AND IN RESPONSE TD 17W
ACCELERATES TO THE WEST-NORTHWEST. AFTER TAU 72 THE SYSTEM WILL
TURN MORE TOWARDS THE NORTHWEST TOWARDS ANOTHER BREAK THAT DEVELOPS
IN THE SUBTROPICAL RIDGE TO THE NORTH. DUE TO THE RATHER
DISORGANIZED LOW-LEVEL VORTEX STRUCTURE, THE CONTINUED PRESENCE OF
DRY MID-LEVEL AIR AND MODERATE EASTERLY SHEAR, THE SYSTEM WILL
STRUGGLE TO DEVELOP THROUGH THE FIRST 72 HOURS, WITH ONLY SLIGHT
INTENSIFICATION EXPECTED AFTER TAU 24 AS THE SHEAR IS EXPECTED TO
WEAKEN A NOTCH OR TWO. AFTER TAU 48, TD 17W IS FORECAST TO REACH
TROPICAL STORM STRENGTH AS IT MOVES INTO A MORE FAVORABLE
ENVIRONMENT OF SLIGHTLY LOWER SHEAR AND ENHANCED MID-LEVEL
MOISTURE, BUT IT WILL CONTINUE TO STRUGGLE AGAINST MODERATE
EASTERLY SHEAR THROUGHOUT THE FORECAST PERIOD.

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN
FAIRLY GOOD AGREEMENT THAT THE SYSTEM WILL REMAIN NEARLY
QUASI-STATIONARY, OR DRIFT SLOWLY WESTWARD, THROUGH THE FIRST 48
HOURS, FOLLOWED BY A MORE RAPID TRACK TO THE NORTHWEST THEREAFTER.
BY TAU 72, THE GUIDANCE ENVELOPE EXPANDS TO JUST 100NM
ACROSS-TRACK, BUT AS MIGHT BE EXPECTED, ALONG-TRACK SPREAD IS MORE
SIGNIFICANT, INCREASING TO 150NM BY TAU 72 BETWEEN THE NAVGEM, AND
THE UKMET AND ECMWF ENSEMBLE MEANS RACING OUT AHEAD OF THE
REMAINDER OF THE GUIDANCE. BY TAU 120, ACROSS-TRACK SPREAD REMAINS
THE SAME WHILE ALONG-TRACK SPREAD INCREASES SHARPLY TO 420NM
BETWEEN THE NAVGEM AND UKMET ENSEMBLE AND THE GFS ENSEMBLE WHICH IS
MUCH SLOWER. THE JTWC FORECAST LIES CLOSE TO THE MULTI-MODEL
CONSENSUS THROUGHOUT THE FORECAST PERIOD WITH LOW CONFIDENCE DUE TO
VERY LARGE ALONG-TRACK SPREAD. INTENSITY GUIDANCE IS MIXED, WITH
THE BULK OF THE GUIDANCE KEEPING THE SYSTEM BELOW 35 KNOTS THROUGH
THE FORECAST PERIOD, WITH THE NOTABLE EXCEPTIONS OF THE COAMPS-TC
(NAVGEM AND GFS VERSIONS) WHICH PEAKS THE SYSTEM BY TAU 96 AT 100
KNOTS AND 70 KNOTS RESPECTIVELY, AND THE HAFS-B WHICH KEEPS THE
SYSTEM AT 25 KNOTS OR LOWER THROUGHOUT THE FORECAST PERIOD. THE
JTWC FORECAST LIES CLOSE TO THE CONSENSUS MEAN THROUGH THE FORECAST
PERIOD WITH LOW CONFIDENCE DUE TO THE EXTREME SPREAD IN THE
GUIDANCE.

FORECAST CONFIDENCE:
TRACK 0 - 72 HR: LOW
TRACK 72-120 HR: LOW
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: LOW//
NNNN

[Sciencerocks]

 https://twitter.com/VortixWx/status/1723717956968890382

[cycloneye]

 https://twitter.com/NWSGuam/status/1723892795667063073

[doomhaMwx]

No way this is a TC. It might have been one at some point when it looked much better yesterday, but obviously not now.

[Hayabusa]

TC warning cancelled, I'd rather not be this named instead of becoming a struggling Jelawat, would be a waste of name.

TD a
Issued at 2023/11/13 13:15 UTC
Analysis at 11/13 12 UTC
Grade TD
Scale -
Intensity -
Center position N7°00′ (7.0°)
E140°00′ (140.0°)
Direction and speed of movement W Slow
Central pressure 1008 hPa

[cycloneye]

FORECAST DISCUSSION: IN THE NEAR-TERM, TD 17W IS LIKELY TO CONTINUE
TO WEAKEN BELOW WARNING CRITERIA AS IT REMAINS QUASI-STATIONARY AND
DRIFTING IN A LOOPING MANNER. NO SIGNIFICANT CHANGE IS EXPECTED IN
THE STRENGTH OF THE EASTERLY SHEAR, AND WHILE SPORADIC CONVECTION
IS LIKELY TO FLARE ALONG LOCALIZED CONVERGENT FLOW LINES, IT IS
UNLIKELY TO BE ABLE TO CONSOLIDATE INTO A COHERENT CORE. BUT WHILE
THE SYSTEM IS FORECAST TO WEAKEN BELOW WARNING CRITERIA, IT IS ALSO
EXPECTED TO REGENERATE LIKE A PHOENIX AFTER TAU 36. BY TAU 36 THE
STEERING GRADIENT IS EXPECTED TO STRENGTHEN, AND TD 17W WILL KICK
OUT TO THE WEST, ACCELERATING PAST PALAU BY TAU 60 BEFORE SLOWING
AND TURNING MORE POLEWARD BY THE END OF THE FORECAST PERIOD. MODEL
FIELDS SUGGESTS A WEAKENING OF THE DEEP-LAYER SHEAR AFTER TAU 36,
WHICH SHOULD ALLOW THEY SYSTEM TO MAKE ANOTHER RUN AT
INTENSIFICATION, ALBEIT SLOWLY AND WEAKLY. BY TAU 36 THE SYSTEM IS
FORECAST TO REGAIN 25 KNOTS, THEN SLOWLY INCREASE TO 35 KNOTS BY
THE END OF THE FORECAST PERIOD, AS IT APPROACHES THE EASTERN
PORTION OF THE PHILIPPINES. HOWEVER, IF CONVECTION FAILS TO DEVELOP
OR THE SYSTEM REMAINS STALLED NEAR ITS CURRENT POSITION, THEN THE
SYSTEM WILL FAIL TO REINTENSIFY AND DISSIPATE WITHIN THE NEXT 36
HOURS.

MODEL DISCUSSION: IN LIGHT OF THE RECENT RELOCATION AND SIGNIFICANT
CHANGE IN THE OVERALL STRUCTURE OF THE STORM, THE FORECAST CAN BE
SUMMED UP AS ONE OF EXTREMELY LOW CONFIDENCE, IN BOTH TRACK AND
INTENSITY. TRACK GUIDANCE IS SCATTERED ACROSS A VERY WIDE SWATH IN
BOTH THE ALONG- AND CROSS-TRACK DIMENSIONS, PRIMARILY IN RESPONSE
TO THE MAJOR SHIFTS IN THE INITIAL POSITION. OF NOTE, THE BULK OF
THE TRACKERS SHOW ONLY A SMALL AMOUNT ADDITIONAL SOUTHWARD MOTION
BEFORE TURNING BACK TO THE WEST. ALL MODELS ARE CONSISTENT WITH A
WEST-NORTHWEST TRACK EXCEPT FOR THE GFS WHICH PERSISTS IN TRACKING
THE SYSTEM DUE WEST AND INTO THE SOUTH CHINA SEA. INTENSITY
GUIDANCE IS FOR THE MOST PART IN GOOD AGREEMENT THAT THE SYSTEM
WILL EITHER WEAKEN SLIGHTLY OR REMAIN STAGNANT FOR THE NEXT 36
HOURS. THEN THE MESOSCALE MODELS SHOW SLOW INTENSIFICATION THROUGH
TAU 96, INCREASING MORE SHARPLY BY THE END OF THE FORECAST.
MEANWHILE THE SHIPS (BOTH VERSIONS) GUIDANCE HOLDS THE SYSTEM
STEADY TO TAU 36, THEN WEAKENS IT TO 20 KNOTS THEN SHARPLY
INCREASES IT AFTER TAU 96 TO 45 KNOTS. COAMPS-TC REMAINS A TRUE
BELIEVER, RAPIDLY INTENSIFYING THE SYSTEM TO 75 KNOTS BY TAU 120,
WHICH GIVEN THE CURRENT STATE OF THINGS, SEEMS HIGHLY UNLIKELY. THE
JTWC FORECAST IS A BLEND OF THE GUIDANCE, GENERALLY BELOW THE
CONSENSUS MEAN, WITH VERY LOW CONFIDENCE.

[zzzh]

It really shows how hostile the WPAC is.

[cycloneye]

 https://twitter.com/NWSGuam/status/1724234008668860499