WPAC: Tropical Depression 12W

[Hayabusa]

98W INVEST 210731 1800 15.8N 154.8E WPAC 15 1008

[Hayabusa]

Expect at least one more invest to be tagged...

[Hayabusa]

ABPW10 PGTW 010230
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
/SOUTH PACIFIC OCEANS REISSUED/010230Z-010600ZAUG2021//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
A. TROPICAL CYCLONE SUMMARY: NONE.
B. TROPICAL DISTURBANCE SUMMARY:
(3) AN AREA OF CONVECTION (INVEST 98W) HAS PERSISTED NEAR
17.8N 153.1E, APPROXIMATELY 551 NM EAST-NORTHEAST OF GUAM. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY AND A 312036Z SSMIS 91GHZ MICROWAVE
PASS SHOW A BROAD AREA OF CONVECTION BEGINNING TO CONSOLIDATE AROUND
A LOW LEVEL CIRCULATION (LLC) WITH STRONG SURFACE CONVERGENCE BEING
INTRODUCED FROM CONSISTENT SOUTHWESTERLY FLOW. A PARTIAL 312300Z
ASCAT-B PASS REVEALS AN ELONGATED LLC WITH 15-20 KNOT WINDS IN THE
EASTERN SEMICIRCLE WITH ISOLATED AREAS OF 25 KNOT WINDS, LIKELY
ASSOCIATED WITH THUNDERSTORM ACTIVITY, AND LOWER WINDS IN THE
WESTERN SEMICIRCLE. RECENT WATER VAPOR ANALYSIS INDICATES INVEST 98W
IS LOCATED DIRECTLY SOUTH OF A TUTT CELL WHICH IS HINDERING
DEVELOPMENT AT THIS TIME. HOWEVER, THE TUTT CELL IS FORECAST TO
SHIFT WEST OVER THE NEXT 24 HOURS, THUS INCREASING UPPER LEVEL
OUTFLOW AND POTENTIALLY DEEPENING INVEST 98W. INVEST 98W IS IN A
MARGINAL ENVIRONMENT WITH ROBUST EQUATORWARD OUTFLOW ALOFT AND WARM
(29-30 C) SEA SURFACE TEMPERATURES, OFFSET BY MODERATE (15-20 KTS)
VERTICAL WIND SHEAR AND UPPER LEVEL CONVERGENCE ASSOCIATED WITH THE
AFOREMENTIONED TUTT CELL. GLOBAL MODELS AGREE INVEST 98W WILL
CONSOLIDATE AS IT TRACKS NORTHWARD OVER THE NEXT 24-36 HOURS.
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 MEDIUM.

[Subtrop]

WTPN22 PGTW 011430
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 98W)//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/010521Z AUG 21//
AMPN/REF IS TROPICAL CYCLONE FORMATION ALERT (WTPN21 PGTW 010530)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
150 NM EITHER SIDE OF A LINE FROM 19.7N 154.3E TO 25.4N 152.6E
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 18 TO 23 KNOTS. METSAT
IMAGERY AT 011200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 20.0N 154.2E. THE SYSTEM IS MOVING NORTHWARD AT 12 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 98W) PREVIOUSLY LOCATED
NEAR 17.5N 153.0E IS NOW LOCATED NEAR 20.0N 154.2E, APPROXIMATELY
766 NM EAST-SOUTHEAST OF IWO-TO. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY DEPICTS A BROAD AREA OF FLARING CONVECTION
OBSCURING AN ILL-DEFINED LOW LEVEL CIRCULATION (LLC). A 010749Z
SSMIS 91GHZ MICROWAVE IMAGE REVEALS DEEP CONVECTION CONCENTRATED IN
THE SOUTHERN PERIPHERY. RECENT WATER VAPOR ANALYSIS INDICATES INVEST
98W IS LOCATED DIRECTLY SOUTH OF A TUTT CELL WHICH IS HINDERING
DEVELOPMENT AT THIS TIME. HOWEVER, THE TUTT CELL IS FORECAST TO
SHIFT WEST, THUS INCREASING UPPER LEVEL OUTFLOW AND POTENTIALLY
DEEPENING INVEST 98W. INVEST 98W IS IN A MARGINAL ENVIRONMENT WITH
ROBUST EQUATORWARD OUTFLOW ALOFT AND WARM (29-30 C) SEA SURFACE
TEMPERATURES, OFFSET BY MODERATE TO HIGH (15-25 KTS) VERTICAL WIND
SHEAR AND UPPER LEVEL CONVERGENCE ASSOCIATED WITH THE AFOREMENTIONED
TUTT CELL. GLOBAL MODELS AGREE INVEST 98W WILL UNDERGO MARGINAL
CONSOLIDATION AS IT TRACKS NORTH-NORTHEASTWARD OVER THE NEXT 24-36
HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 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
021430Z.
4. SEE REF A FOR DETAILS ON A TROPICAL CYCLONE FORMATION ALERT
LOCATED NEAR 26.8N 143.4E.//
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[Hayabusa]

WWJP25 RJTD 020000
WARNING AND SUMMARY 020000.
WARNING VALID 030000.
WARNING IS UPDATED EVERY 6 HOURS.
WARNING.
TROPICAL DEPRESSION 1006 HPA
AT 21.4N 154.9E SEA AROUND OF MINAMITORISIMA MOVING NORTH 10 KNOTS.
POSITION FAIR.
MAX WINDS 30 KNOTS.

[Hayabusa]

Nothing much

[Sciencerocks]

[Sciencerocks]

[Hayabusa]

JTWC started issuing warnings again

WDPN34 PGTW 042100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 12W (TWELVE)
WARNING NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
INITIAL POSITION: 29.4N 140.4E
INITIAL INTENSITY: 25 KTS
GEOGRAPHIC REFERENCE: 356 NM SOUTH OF YOKOSUKA, JAPAN
MOVEMENT PAST 6 HOURS: WESTWARD AT 15 KTS
SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS SHALLOW
CONVECTION ALONG THE SOUTHERN PERIPHERY OF THE SYSTEM WRAPPING INTO
A LOW LEVEL CIRCULATION CENTER THAT IS OBSCURED BY DEEP CONVECTION.
THE SYSTEM STRUCTURE, WHILE DISORGANIZED AND WEAK, HAS IMPROVED
SIGNIFICANTLY AS IS EVIDENCED BY THE CONVECTION AND OUTFLOW BANDS
TO THE NORTH AS WELL AS THE LOW LEVEL CLOUD LINES THAT ARE EVIDENT
IN A 041924Z SSMIS 91 GHZ IMAGE. THE ANIMATED MSI LOOP AND
MICROWAVE IMAGERY LEND OVERALL MEDIUM CONFIDENCE IN THE INITIAL
POSITION. THE INITIAL INTENSITY OF 25 KTS IS PLACED WITH MEDIUM
CONFIDENCE BASED ON A PGTW DVORAK CURRENT INTENSITY ESTIMATE OF
T1.5 (25 KTS).

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

CURRENT STEERING MECHANISM: TRACKING ALONG THE SOUTHERN PERIPHERY
OF NARROW RIDGING POSITIONED OVER EASTERN CHINA AND JAPAN.

AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T1.5 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
VWS: 5-10 KTS
SST: 28-30 CELSIUS
OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TD 12W WILL CONTINUE TO TRACK GENERALLY
WESTWARD TO WEST-SOUTHWESTWARD THROUGH TAU 12 ALONG THE STEERING
RIDGE. THEREAFTER IT WILL BEGIN A NORTHWESTWARD TRACK UNDER THE
STEERING INFLUENCE OF THE RIDGE. GRADUAL INTENSIFICATION WILL
OCCUR THROUGH TAU 24 TO A PEAK OF 35 KTS DUE TO CONTINUED WARM SST
AND LOW VWS. THEREAFTER, TD 12W WILL BE WITHIN 350-400 NM OF TD
14W. THIS CLOSE PROXIMITY WILL LEAD TO DIRECT CYCLONE INTERACTION
AND A POSSIBLE CURVE IN TRACK TO A MORE WEST-NORTHWESTWARD TRACK.
FURTHERMORE, OUTFLOW FROM A STRONGER TD 14W WILL BRING HIGHER VWS
OVER THE SYSTEM AND LEAD TO GRADUAL WEAKENING AND DISSIPATION OVER
WATER BY TAU 48.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIR AGREEMENT ON THE
WESTWARD TO NORTHWESTWARD TRACK FOR THE ENTIRE TRACK FORECAST.
THERE IS DISAGREEMENT ON THE TIMING OF INTENSIFICATION, HOWEVER
MODELS GENERALLY AGREE ON A PEAK OF 35 KTS AS OF THE 18Z RUNS.
OVERALL MODEL SOLUTIONS LENDS MEDIUM AGREEMENT IN THE JTWC TRACK
AND INTENSITY FORECASTS.

FORECAST CONFIDENCE:
TRACK 0 - 72 HR: MEDIUM
INTENSITY 0 - 72 HR: MEDIUM//
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