WPAC: Mun - Tropical Storm

[euro6208]

Ok...

It says based on surface observation, anything to provide?

This is an ongoing problem since JMA started to name TC's and becoming a RSMC since 2000...vs the 41 years that JTWC had since 1959...38 years of them during the recon era.

Really went downhill...Such a shame.

[wxman57]

I can't find any 35 kt winds, nor can I find any organized convection. Typical monsoonal flow is 25-30 kts all summer. Looks like a weak monsoon low, not a TS.

[wxman57]

WTPQ30 RJTD 021200
RSMC TROPICAL CYCLONE PROGNOSTIC REASONING
REASONING NO. 6 FOR TS 1904 Mun (1904)

1.General comments
A TD previously located at 18.8N 112.4E has been upgraded to TS (MUN). TS MUN is located at 18.9N, 111.5E. Information on the current position is based on animated msi and surface observations. Positional accuracy is fair. The system is in a favorable environment for development under the influence of high SSTs and high TCHP This has caused the system to develop over the last six hours. Information on current intensity is based on surface observations. ...snip

Just because SSTs and oceanic heat potential are high doesn't mean that the environment is favorable. There is strong NE-ENE wind shear across the region. Not sure what an "animated msi" is, and I don't see any obs of TS winds.

[StruThiO]

Just because SSTs and oceanic heat potential are high doesn't mean that the environment is favorable. There is strong NE-ENE wind shear across the region. Not sure what an "animated msi" is, and I don't see any obs of TS winds.

Not sure what it could be other than animated multi-spectral imagery

[wxman57]

Just because SSTs and oceanic heat potential are high doesn't mean that the environment is favorable. There is strong NE-ENE wind shear across the region. Not sure what an "animated msi" is, and I don't see any obs of TS winds.

Not sure what it could be other than animated multi-spectral imagery

That's what I was thinking as a possibility (animated msi).

[Grifforzer]

Hong Kong Observatory not following JMA while the other Asian RSMC are using the 35 knots intensity.

AT 021500 UTC, THE TROPICAL DEPRESSION MUN (1904) WITH CENTRAL PRESSURE 996 HECTOPASCALS WAS CENTRED WITHIN 60 NAUTICAL MILES OF ONE EIGHT POINT NINE DEGREES NORTH (18.9 N) ONE ONE ZERO POINT EIGHT DEGREES EAST (110.8 E) AND IS FORECAST TO MOVE WEST OR WEST-NORTHWEST AT ABOUT 8 KNOTS FOR THE NEXT 24 HOURS.

MAXIMUM WINDS NEAR THE CENTRE ARE ESTIMATED TO BE 25 KNOTS.

RADIUS OF OVER 2 METRE WAVES 150 NAUTICAL MILES.

FORECAST POSITION AND INTENSITY AT 031500 UTC
TWO ZERO POINT ONE DEGREES NORTH (20.1 N) ONE ZERO SEVEN POINT EIGHT DEGREES EAST (107.8 E)
MAXIMUM WINDS 35 KNOTS.

FORECAST POSITION AND INTENSITY AT 041500 UTC
DISSIPATED OVER LAND.

[wxman57]

Hong Kong Observatory not following JMA while the other Asian RSMC are using the 35 knots intensity.

AT 021500 UTC, THE TROPICAL DEPRESSION MUN (1904) WITH CENTRAL PRESSURE 996 HECTOPASCALS WAS CENTRED WITHIN 60 NAUTICAL MILES OF ONE EIGHT POINT NINE DEGREES NORTH (18.9 N) ONE ONE ZERO POINT EIGHT DEGREES EAST (110.8 E) AND IS FORECAST TO MOVE WEST OR WEST-NORTHWEST AT ABOUT 8 KNOTS FOR THE NEXT 24 HOURS.

MAXIMUM WINDS NEAR THE CENTRE ARE ESTIMATED TO BE 25 KNOTS.

RADIUS OF OVER 2 METRE WAVES 150 NAUTICAL MILES.

FORECAST POSITION AND INTENSITY AT 031500 UTC
TWO ZERO POINT ONE DEGREES NORTH (20.1 N) ONE ZERO SEVEN POINT EIGHT DEGREES EAST (107.8 E)
MAXIMUM WINDS 35 KNOTS.

FORECAST POSITION AND INTENSITY AT 041500 UTC
DISSIPATED OVER LAND.

Good discussion. Mun represents more of a decrease in the normally strong SW Monsoon across the South China Sea. Looking at satellite, I'd never identify any tropical feature in the region.

[wxman57]

Why is Cat 4 Barbara getting all the attention on this forum. What about the great-looking TS Mun in the South China Sea? Oh, wait, never mind...

[NotoSans]

The following is a flowchart of JMA's operational TC analysis. Unlike NHC which would consider whether there is organised deep convection, JMA only considers whether there is a definite cyclonic circulation (but not necessarily a well-defined one) and winds >34KT. It is likely that JMA has a very lenient definition for TC, but this definition really varies across basins.

[Hayabusa]

Beautiful storm

[euro6208]

TCFA cancelled. JTWC classifies this as a monsoon depression and they dont use that term.

WTPN21 PGTW 022030
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 96W) CANCELLATION//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/012051ZJUL19//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.//
RMKS/
1. REMARKS: THIS CANCELS REF A (WTPN21 PGTW 012100). THE AREA OF
CONVECTION (INVEST 96W) PREVIOUSLY LOCATED NEAR 17.8N 113.3E, IS NOW
LOCATED NEAR 19.0N 111.3E, APPROXIMATELY 95 NM SOUTHEAST OF HAIKOU,
CHINA. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A 021556Z
GMI 89GHZ MICROWAVE IMAGE, SHOWS A BROAD LOW LEVEL CIRCULATION (LLC)
WITH SHEARED DEEP CONVECTION CONCENTRATED ALONG THE SOUTHWEST
PERIPHERY OF THE CIRCULATION. A 021259Z METOP-A ASCAT PASS CONFIRMS
AN ELONGATED LLC WITH 25-30 KNOT ENVIRONMENTAL WINDS
TO THE SOUTHEAST. BASED ON THE STRUCTURE OF THE CIRCULATION, JTWC IS
ASSESSING THE CIRCULATION AS A MONSOON DEPRESSION. 96W IS CURRENTLY
IN A MARGINAL ENVIRONMENT WITH FAIR EQUATORWARD OUTFLOW AND WARM (28-
29 CELSIUS) SEA SURFACE TEMPERATURE BEING OFFSET BY STRONG (30-35
KNOT) VERTICAL WIND SHEAR. GLOBAL MODELS DEPICT 96W CONTINUING TO
TRACK GENERALLY NORTHWEST ACROSS HAINAN WITH A SMALL CHANCE FOR THE
CIRCULATION TO DEVELOP INTO A TROPICAL CYCLONE BEFORE MAKING
LANDFALL NEAR THE VIETNAM-CHINA BORDER. MAXIMUM SUSTAINED SURFACE
WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1021 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS DOWNGRADED
TO MEDIUM.//
NNNN

[NotoSans]

Convective burst after MUN enters the Gulf of Tonkin - a typical case I'd say.

[euro6208]

THE AREA OF CONVECTION (INVEST 96W) PREVIOUSLY LOCATED
NEAR 19.0N 111.3E, IS NOW LOCATED NEAR 19.4N 109.1E, APPROXIMATELY
204 NM EAST-SOUTHEAST OF HANOI, VIETNAM. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY SHOWS A BROAD, FULLY EXPOSED LOW LEVEL CIRCULATION
(LLC) WITH HIGHLY SHEARED DEEP CONVECTION TO THE SOUTHWEST. A
030245Z ASCAT PASS SHOWS THE ELONGATED LLC WITH 30-35KT WINDS FROM
THE SOUTHWEST ALONG THE SOUTHEASTERN PERIPHERY AND 15-20KT WINDS
ELSEWHERE IN THE CIRCULATION. 96W IS IN A MARGINAL ENVIRONMENT WITH
STRONG NORTHEASTERLY VERTICAL WIND SHEAR (35-40KTS), MODERATE UPPER
LEVEL OUTFLOW AND FAVORABLE SEA SURFACE TEMPERATURES (29-30C).
GLOBAL MODELS DEPICT 96W CONTINUING TO TRACK WESTWARD WITHOUT
INTENSIFYING BEFORE MAKING LANDFALL IN VIETNAM. JTWC IS STILL
ASSESSING THIS DISTURBANCE AS A MONSOON DEPRESSION. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 995 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS REMAINS MEDIUM.

[1900hurricane]

[1900hurricane]

JTWC did end up giving Mun the 05W designation.

Code: Select all

WTPN31 PGTW 032100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL STORM 05W (MUN) WARNING NR 001//
RMKS/
1. TROPICAL STORM 05W (MUN) WARNING NR 001   
   UPGRADED FROM TROPICAL DEPRESSION 05W
   01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   031800Z --- NEAR 20.2N 107.1E
     MOVEMENT PAST SIX HOURS - 305 DEGREES AT 09 KTS
     POSITION ACCURATE TO WITHIN 045 NM
     POSITION BASED ON CENTER LOCATED BY A COMBINATION OF
     SATELLITE AND SYNOPTIC DATA
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 075 NM NORTHEAST QUADRANT
                            090 NM SOUTHEAST QUADRANT
                            090 NM SOUTHWEST QUADRANT
                            060 NM NORTHWEST QUADRANT
   REPEAT POSIT: 20.2N 107.1E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   040600Z --- 21.0N 106.0E
   MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
   VECTOR TO 24 HR POSIT: 325 DEG/ 06 KTS
    ---
   24 HRS, VALID AT:
   041800Z --- 21.9N 105.3E
   MAX SUSTAINED WINDS - 015 KT, GUSTS 025 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
    ---
REMARKS:
032100Z POSITION NEAR 20.4N 106.8E.
TROPICAL STORM 05W (MUN), LOCATED APPROXIMATELY 83 NM SOUTHEAST
OF HANOI, VIETNAM, HAS TRACKED NORTHWESTWARD AT 09 KNOTS OVER THE
PAST SIX HOURS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 031800Z IS 13
FEET. NEXT WARNINGS AT 040300Z, 040900Z AND 041500Z.//
NNNN

WDPN31 PGTW 032100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (MUN)
WARNING NR 01//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 05W (MUN), LOCATED APPROXIMATELY 83 NM
SOUTHEAST OF HANOI, VIETNAM, HAS TRACKED NORTHWESTWARD AT 09 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS A BROAD LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
LIMITED DEEP CONVECTION SHEARED TO THE SOUTHWEST DUE TO STRONG (25
TO 40 KNOTS) NORTHEASTERLY WIND SHEAR. HOWEVER, RECENT MICROWAVE
IMAGERY (SPECIFICALLY, THE 031812Z AMSR2 36GHZ AND 031104Z WINDSAT
37GHZ IMAGES) AND SURFACE OBSERVATIONS FROM BACH LONG VI (48839)
PROVIDE EVIDENCE THAT THE SYSTEM CONSOLIDATED INTO A TROPICAL
CYCLONE AS IT TRACKED AWAY FROM HAINAN ISLAND WITH IMPROVED LOW-
LEVEL BANDING AND STRUCTURE ALONG THE SOUTHERN AND EASTERN
SEMICIRCLES. ALTHOUGH THE SYSTEM REMAINS BROAD, RECENT ASCAT DATA
AND SURFACE OBSERVATIONS INDICATE 30-35 KNOT WINDS OVER THE SOUTHERN
AND EASTERN SEMICIRCLES WITH A RADIUS OF MAXIMUM WINDS OF 35-50NM,
WHICH IS TYPICAL OF A TROPICAL CYCLONE. OVERALL, THERE IS FAIR
CONFIDENCE IN THE INITIAL POSITION BASED ON THE 031812Z AMSR2 IMAGE
AND MULTIPLE SURFACE OBSERVATIONS.
3. FORECAST REASONING.
A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE AND SETS THE
FORECAST PHILOSOPHY.
B. TS 05W IS TRACKING NORTHWESTWARD ALONG THE SOUTHWEST PERIPHERY
OF THE LOW-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST
AND IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD THROUGH THE
FORECAST PERIOD. NUMERICAL MODEL GUIDANCE DIVERGES AS THE SYSTEM
TRACKS INLAND, THEREFORE, THERE IS MODERATE CONFIDENCE IN THE JTWC
FORECAST TRACK. TS MUN IS EXPECTED TO MAKE LANDFALL WITHIN THE NEXT
SIX HOURS WITH RAPID WEAKENING DUE TO INCREASING FRICTIONAL EFFECTS
AND PERSISTENT STRONG VERTICAL WIND SHEAR. THE SYSTEM SHOULD
DISSIPATE OVER NORTHERN VIETNAM BY TAU 24.//
NNNN

[euro6208]

WTPN31 PGTW 040300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL DEPRESSION 05W (MUN) WARNING NR 002
DOWNGRADED FROM TROPICAL STORM 05W
01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
040000Z --- NEAR 20.7N 106.1E
MOVEMENT PAST SIX HOURS - 300 DEGREES AT 11 KTS
POSITION ACCURATE TO WITHIN 030 NM
POSITION BASED ON CENTER LOCATED BY A COMBINATION OF
SATELLITE AND SYNOPTIC DATA
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
REPEAT POSIT: 20.7N 106.1E
---
FORECASTS:
12 HRS, VALID AT:
041200Z --- 21.4N 105.2E
MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 24 HR POSIT: 335 DEG/ 05 KTS
---
24 HRS, VALID AT:
050000Z --- 22.3N 104.7E
MAX SUSTAINED WINDS - 015 KT, GUSTS 025 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
040300Z POSITION NEAR 20.9N 105.9E.
TROPICAL DEPRESSION (TD) 05W (MUN), LOCATED APPROXIMATELY 21 NM
SOUTH-SOUTHEAST OF HANOI, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD AT
11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A FULLY-EXPOSED, DEFINED LOW-LEVEL CIRCULATION WITH
DEEP CONVECTION SHEARED TO THE SOUTHWEST DUE TO STRONG (25 TO 40
KNOTS) NORTHEASTERLY WIND SHEAR. OVERALL, THERE IS GOOD CONFIDENCE
IN THE INITIAL POSITION OVER LAND, WHICH IS ALSO SUPPORTED BY
SURFACE OBSERVATIONS FROM NAM DINH (48823) AND HA DONG (48825). THE
INITIAL INTENSITY IS ASSESSED AT 30 KNOTS BASED ON STRUCTURE, HEDGED
ABOVE THE RJTD DVORAK INTENSITY ESTIMATE OF T1.5 (25 KNOTS). TD 05W
IS TRACKING WEST-NORTHWESTWARD ALONG THE SOUTHWEST PERIPHERY OF THE
LOW-LEVEL SUBTROPICAL RIDGE POSITIONED TO THE NORTHEAST AND IS
FORECAST TO CONTINUE TRACKING WEST-NORTHWESTWARD TO NORTHWESTWARD
THROUGH THE FORECAST PERIOD. NUMERICAL MODEL GUIDANCE DIVERGES AS
THE SYSTEM TRACKS INLAND, THEREFORE, THERE IS MODERATE CONFIDENCE IN
THE JTWC FORECAST TRACK. TD 05W IS EXPECTED TO DISSIPATE OVER
NORTHERN VIETNAM BY TAU 12. 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 040000Z IS 13 FEET.//
NNNN