WPAC: OMAIS - Post Tropical

[1900hurricane]

Looks to me it took in some dry air produced from subsidence beneath the subtropical ridge to the west. And it was just starting to look respectable too...

[Alyono]

just wondering what is up with JT on this one. They say the max winds are 45 kts. The ASCAT shows a LARGE area of 50 kt winds, meaning peak winds are closer to 60 kts.

All Dvorak yet again? Dvorak will ALWAYS underestimate these types of storms

[euro6208]

WDPN31 PGTW 070300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (OMAIS) WARNING NR
11//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 07W (OMAIS), LOCATED APPROXIMATELY 540 NM
SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHWARD AT 12 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS
A BROAD AND ILL DEFINED FULLY EXPOSED LOW LEVEL CIRCULATION CENTER
(LLCC), WITH DEEP CONVECTION REMAINING ONLY ALONG THE EASTERN SEMI-
CIRCLE. THE CURRENT POSITION IS BASED ON THE PGTW FIX AND MSI WITH
GOOD CONFIDENCE. THE CURRENT INTENSITY IS ASSESSED AT 45 KNOTS BASED
ON THE PRONOUNCED WEAKENING TREND, WITH A PGTW DVORAK CURRENT
INTENSITY ESTIMATE OF 45 KNOTS. ENVIRONMENTAL CONDITIONS ARE FAIR,
WITH GOOD RADIAL OUTFLOW AND LOW (5-10 KNOTS) VERTICAL WIND SHEAR
(VWS) BEING OFFSET BY THE EFFECTS OF DRY AIR ENTRAINMENT AND
DECREASING SEA SURFACE TEMPERATURES (SSTS). TS 07W IS TRACKING
POLEWARD ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED SUB-TROPICAL
RIDGE (STR) POSITIONED TO THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 07W WILL CONTINUE TO TRACK GENERALLY NORTHWESTWARD TO
NORTHWARD ALONG THE WESTERN PERIPHERY OF THE STEERING STR OVER THE
NEXT 36 HOURS. AFTER TAU 36, IT WILL ROUND THE STR AND TURN TO THE
NORTHEAST. BASED ON THE COMPETING ENVIRONMENTAL INFLUENCES, OMAIS
SHOULD HOLD A FAIRLY STEADY INTENSITY OVER THE NEXT 36-48 HOURS,
PRIOR TO AN INCREASE IN VWS ASSOCIATED WITH AN APPROACHING MID-
LATITUDE TROUGH. TS 07W WILL BEGIN EXTRATROPICAL TRANSITION (ETT) BY
TAU 48 AS THE NORTHERN PERIPHERY OF THIS LARGE SYSTEM BEGINS TO
INTERACT WITH THE TROUGH, AND THE LLCC MOVES OVER 25 DEGREE CELSIUS
WATERS. AS THE SYSTEM ACCELERATES NORTHEASTWARD, IT WILL QUICKLY
COMPLETE ETT AND BECOME FULLY EMBEDDED WITHIN THE MID-LATITUDE
BAROCLINIC FLOW BY TAU 72. DYNAMICAL MODELS ARE IN GOOD AGREEMENT,
GIVING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK.//
NNNN

[Alyono]

as I said YOU DO NOT USE DVORAK FOR THIS TYPE OF SYSTEM

LOOK AT THE DATA!

JMA did. They have 10 min winds of 60 kts. Even higher than the 1 min winds of 60 kts that I have

[Kingarabian]

JTWC is located in Hawaii right? That fact, should explain everything.

[NotoSans]

THE INITIAL INTENSITY REMAINS AT 45 KNOTS BASED ON A PREVIOUS ASCAT PASS WITH A LARGE REGION OF 40 TO 45 KNOT WINDS ALONG THE WESTERN SEMI-CIRCLE.

But there are 50-kt wind barbs

[Alyono]

The following is not a bash. it is a professional observation

The one who wrote that discussion does not understand tropical cyclone dynamics. How can the winds west of the center in a northward moving cyclone not be weaker than the winds east of the center, especially with the convection being confined to the east semi-circle? If the winds are 45 kt in the left quadrant, they would likely be 65 kt in the right quad

[euro6208]

WDPN31 PGTW 070900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (OMAIS) WARNING NR
12//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 07W (OMAIS), LOCATED APPROXIMATELY 474 NM
SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT
12 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A BROAD AND ILL-DEFINED LOW LEVEL CIRCULATION CENTER
(LLCC) WITH MULTIPLE MESO-VORTICIES ROTATING CYCLONICALLY AROUND THE
CENTER. A 070420Z AMSU-B MICROWAVE IMAGE REVEALS THAT THE CONVECTIVE
STRUCTURE HAS CONTINUED TO DIMINISH DUE TO DRY AIR ENTRAINMENT FROM
THE WEST. THE CURRENT POSITION IS PLACED IN THE CENTER OF THE
BROAD CIRCULATION WITH LOW CONFIDENCE. THE INITIAL INTENSITY REMAINS
AT 45 KNOTS BASED ON A PREVIOUS ASCAT PASS WITH A LARGE REGION OF 40
TO 45 KNOT WINDS ALONG THE WESTERN SEMI-CIRCLE. ENVIRONMENTAL
ANALYSIS DEPICTS A MARGINAL TO POOR ENVIRONMENT DUE TO THE
AFOREMENTIONED DRY AIR AND DECREASING SEA SURFACE TEMPERATURES
(SSTS). TS 07W IS TRACKING POLEWARD ALONG THE WESTERN PERIPHERY OF A
DEEP-LAYERED SUB-TROPICAL RIDGE (STR) POSITIONED TO THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 07W WILL CONTINUE TO TRACK GENERALLY NORTHWESTWARD TO
NORTHWARD ALONG THE WESTERN PERIPHERY OF THE STEERING STR OVER THE
NEXT 36 HOURS. AFTER TAU 36, IT WILL ROUND THE STR AXIS AND TURN TO
THE NORTHEAST. TS OMAIS WILL MAINTAIN ITS CURRENT INTENSITY AS
DECENT OUTFLOW AND LOW VERTICAL WIND SHEAR HELP OFFSET THE DRY AIR
AND DECREASING SSTS. THE SYSTEM WILL INTERACT WITH AN APPROACHING
UPPER LEVEL TROUGH NEAR TAU 36, BEGINNING EXTRATROPICAL TRANSITION
(ETT). TS 07W IS EXPECTED TO COMPLETE ETT BY THE END OF THE FORECAST
PERIOD AS A STRONG COLD-CORE LOW. DYNAMIC MODEL GUIDANCE REMAINS IN
VERY TIGHT AGREEMENT, LENDING HIGH CONFIDENCE TO THE JTWC TRACK
FORECAST.//
NNNN

[euro6208]

WDPN31 PGTW 072100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (OMAIS) WARNING NR
14//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 07W (OMAIS), LOCATED APPROXIMATELY 323 NM
SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT 13
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS A RAGGED LOW LEVEL CIRCULATION CENTER (LLCC)
SURROUNDED BY A BROAD BUT ASYMMETRIC AREA OF CURVED BANDING. A
071155Z ASCAT PASS REVEALS A LARGE SWATH OF 50 KNOT WINDS REMAINS IN
THE NORTHEAST QUADRANT, AND ALSO INDICATES THE SOUTHWEST QUADRANT NO
LONGER CONTAINS 35 KNOT WINDS. A 071821Z SSMIS 37 GHZ IMAGE REFLECTS
THE ILL DEFINED NATURE OF THE LLCC, BUT GENERALLY SUPPORTS THE
INITIAL POSITION. THE INITIAL POSITION IS BASED ON THE PGTW FIX AND
AFOREMENTIONED SSMIS PASS WITH FAIR CONFIDENCE. THE INITIAL
INTENSITY HAS BEEN REVISED BACK UP TO 50 KNOTS BASED ON THE ASCAT
PASS, AND IS HIGHER THAN DVORAK ESTIMATES WHICH ARE NOT
REPRESENTATIVE FOR THIS VERY LARGE SYSTEM. THE ENVIRONMENT IS NOT
SUPPORTIVE FOR FURTHER DEVELOPMENT, WITH DRY AIR ENTRAINMENT AND
MINIMALLY SUPPORTIVE SEA SURFACE TEMPERATURES (SSTS). TS 07W IS
TRACKING POLEWARD ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED SUB-
TROPICAL RIDGE (STR) POSITIONED TO THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 07W IS EXPECTED TO ROUND THE STR AND RECURVE TO THE
NORTHEAST OVER THE NEXT 24 HOURS. PEAK WINDS WILL DECAY VERY SLOWLY
DUE TO THE LARGE SCALE OF THE CIRCULATION, COMBINED WITH CONTINUED
GOOD OUTFLOW. THE SYSTEM WILL BEGIN EXTRATROPICAL TRANSITION (ETT)
NEAR TAU 24, AS THE NORTHERN PERIPHERY BEGINS TO INTERACT WITH AN
APPROACHING UPPER LEVEL TROUGH. TS 07W WILL COMPLETE ETT BY THE END
OF THE FORECAST PERIOD AS IT EMBEDS IN THE MID-LATITUDE WESTERLY
FLOW AND ACCERLERATES TO THE NORTHEAST. DYNAMIC MODEL GUIDANCE
REMAINS IN VERY TIGHT AGREEMENT, LENDING HIGH CONFIDENCE TO THE JTWC
TRACK FORECAST.//
NNNN

[euro6208]

WDPN31 PGTW 080300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (OMAIS) WARNING NR
15//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 07W (OMAIS), LOCATED APPROXIMATELY 251 NM
EAST-SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD
AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY DEPICTS MULTIPLE VORTICES ORBITING A VERY ILL-
DEFINED LOW LEVEL CIRCULATION CENTER (LLCC), SURROUNDED BY A BROAD
AREA OF INCREASINGLY SHALLOW CONVECTION. TIGHTLY CURVED BANDING CAN
STILL BE OBSERVED IN A 072105Z CORIOLIS 37 GHZ PASS, ALTHOUGH THE
LLCC REMAINS ILL DEFINED EVEN IN THE MICROWAVE IMAGERY. THE INITIAL
POSITION IS BASED ON FIXES FROM PGTW AND RJTD, HOWEVER, THERE IS
POOR CONFIDENCE DUE TO THE LACK OF A CLEAR LLCC. THE INITIAL
INTENSITY HAS BEEN HELD AT 50 KNOTS BASED ON AN EARLIER ASCAT PASS,
AS DVORAK ESTIMATES ARE NOT REPRESENTATIVE FOR THIS VERY LARGE
SYSTEM. THE ENVIRONMENT IS NOT SUPPORTIVE FOR FURTHER DEVELOPMENT,
WITH DRY AIR ENTRAINMENT AND MINIMALLY SUPPORTIVE SEA SURFACE
TEMPERATURES (SSTS). TS 07W IS TRACKING POLEWARD ALONG THE WESTERN
PERIPHERY OF A DEEP-LAYERED SUB- TROPICAL RIDGE (STR) POSITIONED TO
THE EAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 07W IS EXPECTED TO ROUND THE STR AND RECURVE TO THE
NORTHEAST OVER THE NEXT 12-24 HOURS. PEAK WINDS WILL DECAY SLOWLY
DUE TO THE LARGE SCALE OF THE CIRCULATION, COMBINED WITH CONTINUED
GOOD OUTFLOW. THE SYSTEM WILL BEGIN EXTRATROPICAL TRANSITION (ETT)
AROUND TAU 24, AS THE NORTHERN PERIPHERY BEGINS TO INTERACT WITH AN
APPROACHING UPPER LEVEL TROUGH. TS 07W WILL COMPLETE ETT BY THE END
OF THE FORECAST PERIOD AS IT EMBEDS IN THE MID-LATITUDE WESTERLY
FLOW AND ACCERLERATES TO THE NORTHEAST AS A GALE FORCE LOW. DYNAMIC
MODEL GUIDANCE REMAINS IN VERY TIGHT AGREEMENT, LENDING HIGH
CONFIDENCE TO THE JTWC TRACK FORECAST.//
NNNN

[stormwise]

[euro6208]

WTPN31 PGTW 082100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL STORM 07W (OMAIS) WARNING NR 018
02 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
081800Z --- NEAR 36.8N 144.7E
MOVEMENT PAST SIX HOURS - 010 DEGREES AT 12 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
BECOMING EXTRATROPICAL
RADIUS OF 034 KT WINDS - 210 NM NORTHEAST QUADRANT
220 NM SOUTHEAST QUADRANT
075 NM SOUTHWEST QUADRANT
175 NM NORTHWEST QUADRANT
REPEAT POSIT: 36.8N 144.7E
---
FORECASTS:
12 HRS, VALID AT:
090600Z --- 39.9N 146.7E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
EXTRATROPICAL
VECTOR TO 24 HR POSIT: 035 DEG/ 22 KTS
---
24 HRS, VALID AT:
091800Z --- 43.6N 150.0E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
EXTRATROPICAL
---
REMARKS:
082100Z POSITION NEAR 37.6N 145.2E.
TROPICAL STORM 07W (OMAIS), LOCATED APPROXIMATELY 259 NM EAST-
NORTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTH AT 12 KNOTS OVER THE
PAST SIX HOURS. THE SYSTEM WILL ACCELERATE TO THE NORTH-NORTHEAST
AND CONTINUE TO LOSE ITS TROPICAL CHARACTERISTICS AS IT INTERACTS
WITH THE BAROCLINIC ZONE, WITH STRONGEST WINDS AND CONVECTION
REMAINING AROUND THE PERPHERY OF THE CIRCULATION. THIS IS THE FINAL
WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI.
THE SYSTEM WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 081800Z IS 24 FEET.
REFER TO TROPICAL STORM 08W (EIGHT) WARNINGS (WTPN32 PGTW)
FOR SIX-HOURLY UPDATES.
//
NNNN