WPAC: MALAKAS - Post-Tropical

[1900hurricane]

Current radar from Guam. I wonder how much the radar and local obs played in the upgrade.

[euro6208]

Next name on the list...Rai.

[euro6208]

Receiving very heavy rains this morning and winds gusting up to 40 mph....Time for work...

[euro6208]

WDPN33 PGTW 112100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 18W (EIGHTEEN)
WARNING NR 01//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 18W (EIGHTEEN), LOCATED APPROXIMATELY 31
NM SOUTH OF HAGATNA, GUAM, HAS TRACKED WEST-NORTHWESTWARD AT 15
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY AND RADAR IMAGERY INDICATE A CONSOLIDATING LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH IMPROVED CONVECTIVE STRUCTURE. A
111723Z SSMI 85GHZ IMAGE REVEALS MULTIPLE CONVECTIVE BANDS WRAPPING
INTO AN ELONGATED, WELL-DEFINED CENTER. THE MOST RECENT SURFACE
OBSERVATIONS FROM PGUM SHOW SUSTAINED SURFACE WINDS OF 25 TO 30
KNOTS WITH GUSTS UP TO 35 TO 40 KNOTS. THE CURRENT INTENSITY IS
ASSESSED AT 30 KNOTS BASED ON THE IMPROVED CONVECTIVE STRUCTURE AND
SURFACE WIND REPORTS FROM GUAM; THE DVORAK INTENSITY ESTIMATES OF
T1.5 (25 KNOTS) ARE SLIGHTLY LOWER THAN THE CURRENT INTENSITY
ESTIMATE. UPPER-LEVEL ANALYSIS DEPICTS A VERY FAVORABLE ENVIRONMENT
WITH AN ENHANCED POLEWARD OUTFLOW CHANNEL ASSOCIATED WITH A BROAD
TUTT CELL TO THE NNE AND LOW VERTICAL WIND SHEAR. TD 18W IS TRACKING
ALONG THE SOUTHERN PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE
(STR) ENTRENCHED TO THE NORTH.
3. FORECAST REASONING.
A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE FOR 18W AND
SETS THE FORECAST PHILOSOPHY.
B. TD 18W IS FORECAST TO TRACK WEST-NORTHWESTWARD TO
NORTHWESTWARD THROUGH TAU 72. THE STR IS FORECAST TO ERODE WITH THE
SLOW APPROACH OF A MAJOR SHORTWAVE TROUGH (CURRENTLY OVER EASTERN
CHINA AND IMPACTING THE FORECAST TRACK OF TY 16W). THIS FORECAST
SCENARIO IS CONSISTENT WITH THAT OF TY 16W AS BOTH SYSTEMS WILL BE
AFFECTED BY THE MAJOR SHORTWAVE TROUGH AS IT PROGRESSES EASTWARD.
DYNAMIC GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72 WITH A 100-NM
SPREAD IN SOLUTIONS AT TAU 72. TD 18W IS FORECAST TO INTENSIFY
RAPIDLY OVER THE NEXT TWO TO THREE DAYS DUE TO THE ROBUST POLEWARD
OUTFLOW ASSOCIATED WITH THE AFOREMENTIONED TUTT CELL, WHICH IS
EXPECTED TO TRACK WESTWARD WITH THE SYSTEM. CONSEQUENTLY, PEAK
INTENSITY SHOULD BE NEAR 115 KNOTS (OR HIGHER) BY TAU 72.
C. AFTER TAU 72, TD 18W IS FORECAST TO TRACK POLEWARD TOWARD
OKINAWA ALONG THE WESTERN PERIPHERY OF THE POLEWARD-ORIENTED STR.
DYNAMIC GUIDANCE DIVERGES WITH A SPREAD OF 300-NM IN SOLUTIONS AT
TAU 120. DYNAMIC GUIDANCE INDICATES INCREASING UNCERTAINTY WITH
MODEL SOLUTIONS JUST EAST OF ISHIGAKI-JIMA TO JUST EAST OF OKINAWA;
THESE SOLUTIONS ARE ALL VIABLE CONSIDERING THE COMPLEX TIMING OF THE
MAJOR SHORTWAVE TROUGH OVER EASTERN CHINA AND THE EAST CHINA SEA. TD
18W SHOULD WEAKEN GRADUALLY AS IT INTERACTS WITH THE TROUGH.
OVERALL, THERE IS LOW CONFIDENCE (LARGE MODEL SPREAD) IN THE JTWC
FORECAST, PARTICULARLY AFTER TAU 72.//
NNNN

[euro6208]

000
WTPQ33 PGUM 112112
TCPPQ3

BULLETIN
TROPICAL DEPRESSION 18W ADVISORY NUMBER 1
NATIONAL WEATHER SERVICE TIYAN GU WP182016
800 AM CHST MON SEP 12 2016

...TROPICAL DEPRESSION 18W FORMS SOUTHWEST OF GUAM...

CHANGES WITH THIS ADVISORY
--------------------------
NONE.

WATCHES AND WARNINGS
--------------------
NONE.

SUMMARY OF 700 AM CHST...2100 UTC...INFORMATION
-----------------------------------------------
LOCATION...12.9N 144.1E

ABOUT 60 MILES SOUTHWEST OF GUAM
ABOUT 110 MILES SOUTHWEST OF ROTA
ABOUT 175 MILES SOUTHWEST OF TINIAN
ABOUT 190 MILES NORTHWEST OF SAIPAN
ABOUT 470 MILES EAST-NORTHEAST OF YAP

MAXIMUM SUSTAINED WINDS...35 MPH
PRESENT MOVEMENT...WEST-NORTHWEST...290 DEGREES AT 17 MPH

DISCUSSION AND OUTLOOK
----------------------
AT 700 AM CHST...2100 UTC...THE CENTER OF TD 18W WAS LOCATED
NEAR LATITUDE 12.9 DEGREES NORTH AND LONGITUDE 144.1 DEGREES EAST.
18W IS HEADING WEST-NORTHWEST AT 17 MPH. THIS GENERAL MOTION IS
EXPECTED TO CONTINUE THE NEXT FEW DAYS.

MAXIMUM SUSTAINED WINDS ARE 35 MPH. 18W IS EXPECTED TO INTENSIFY
OVER THE NEXT FEW DAYS AND COULD BECOME A TROPICAL STORM LATER
TODAY.

NEXT ADVISORY
-------------
THE NEXT SCHEDULED ADVISORY WILL BE ISSUED BY THE NATIONAL WEATHER
SERVICE AT 200 PM THIS AFTERNOON.

$$

KLEESCHULTE

[wxmann_91]

The first forecast for 18W looks eerily similar to what the first forecast looked for Meranti.

[Alyono]

how is this a TD when they do not call the OBVIOUS TD in the South China Sea?

[euro6208]

WDPN33 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 18W (EIGHTEEN)
WARNING NR 02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 18W (EIGHTEEN), LOCATED APPROXIMATELY 82
NM WEST OF NAVSTA GUAM, HAS TRACKED WEST-NORTHWESTWARD AT 15 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
INDICATES A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
RAPIDLY IMPROVING CONVECTIVE STRUCTURE. A 112108Z NOAA-18 89GHZ IMAGE
SHOWS DEEP CONVECTIVE BANDING OVER THE SOUTHERN SEMI-CIRCLE WRAPPING
INTO THE LLCC WITH FRAGMENTED BANDING ELSEWHERE. THE CURRENT
INTENSITY IS ASSESSED AT 30 KNOTS BASED ON A PGTW DVORAK ESTIMATE OF
T2.0, CONSISTENT WITH THE IMPROVED CONVECTIVE STRUCTURE. UPPER-LEVEL
ANALYSIS DEPICTS A VERY FAVORABLE ENVIRONMENT WITH NEAR-RADIAL
OUTFLOW, AND AN ENHANCED POLEWARD OUTFLOW CHANNEL ASSOCIATED WITH A
BROAD TUTT CELL TO THE NNE. TD 18W IS TRACKING ALONG THE SOUTHERN
PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) ENTRENCHED TO
THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TD 18W IS FORECAST TO TRACK WEST-NORTHWESTWARD TO
NORTHWESTWARD THROUGH TAU 72. THE STR IS FORECAST TO ERODE WITH THE
SLOW APPROACH OF A MAJOR SHORTWAVE TROUGH (CURRENTLY OVER EASTERN
CHINA AND IMPACTING THE FORECAST TRACK OF TY 16W). THIS FORECAST
SCENARIO IS CONSISTENT WITH THAT OF TY 16W AS BOTH SYSTEMS WILL BE
AFFECTED BY THE MAJOR SHORTWAVE TROUGH AS IT PROGRESSES EASTWARD.
DYNAMIC GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72 WITH A 100-NM
SPREAD IN SOLUTIONS AT TAU 72. TD 18W IS FORECAST TO INTENSIFY
RAPIDLY OVER THE NEXT TWO TO THREE DAYS DUE TO THE ROBUST POLEWARD
OUTFLOW ASSOCIATED WITH THE AFOREMENTIONED TUTT CELL, WHICH IS
EXPECTED TO TRACK WESTWARD WITH THE SYSTEM. CONSEQUENTLY, PEAK
INTENSITY SHOULD BE NEAR 115 KNOTS (OR HIGHER) BY TAU 72.
C. AFTER TAU 72, TD 18W IS FORECAST TO TRACK POLEWARD TOWARD
OKINAWA ALONG THE WESTERN PERIPHERY OF THE POLEWARD-ORIENTED STR.
DYNAMIC GUIDANCE DIVERGES WITH A SPREAD OF 450-NM IN SOLUTIONS AT
TAU 120. DYNAMIC GUIDANCE INDICATES INCREASING UNCERTAINTY WITH
MODEL SOLUTIONS JUST WEST OF ISHIGAKI-JIMA TO JUST EAST OF OKINAWA;
THESE SOLUTIONS ARE ALL VIABLE CONSIDERING THE COMPLEX TIMING OF THE
MAJOR SHORTWAVE TROUGH OVER EASTERN CHINA AND THE EAST CHINA SEA. TD
18W SHOULD WEAKEN GRADUALLY AS IT INTERACTS WITH THE TROUGH.
OVERALL, THERE IS LOW CONFIDENCE (LARGE MODEL SPREAD) IN THE JTWC
FORECAST, PARTICULARLY AFTER TAU 72.//
NNNN

[euro6208]

18W EIGHTEEN 160912 0600 13.1N 141.7E WPAC 40 1003

[euro6208]

TPPN10 PGTW 120624

A. TROPICAL DEPRESSION 18W (EIGHTEEN)

B. 12/0540Z

C. 12.99N

D. 141.66E

E. FIVE/HMWRI8

F. T3.0/3.0 STT: D1.0/03HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 40A/PBO SBC/ANMTN. CNVCTN WRAP OF .70 ON LOG10 SPIRAL
YIELDS A DT OF 3.0. MET AND PT UNAVAILABLE. DBO DT.

I. ADDITIONAL POSITIONS: NONE

DREW

[euro6208]

WDPN33 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (EIGHTEEN)
WARNING NR 03//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 18W (EIGHTEEN), LOCATED APPROXIMATELY 170 NM WEST
OF NAVSTA GUAM, HAS TRACKED WESTWARD AT 15 KNOTS OVER THE PAST SIX
HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 120549Z MHS
89GHZ MICROWAVE IMAGE SHOWS THE SYSTEM BECOMING BETTER ORGANIZED
WITH DEEP CONVECTION WRAPPING INTO THE LOW-LEVEL CIRCULATION CENTER
(LLCC) WITH IMPROVED BANDING. THE INITIAL POSITION IS PLACED WITH
FAIR CONFIDENCE. THE CURRENT INTENSITY IS ASSESSED AT 40 KNOTS,
GIVEN DVORAK ESTIMATES RANGING FROM T1.5 (RJTD) TO T3.0 (PGTW). TS
18W IS IN A REGION OF MODERATE NORTHWESTERLY VERTICAL WIND SHEAR (20
TO 25 KNOTS) ASSOCIATED WITH THE EASTERN PORTION OF THE UPPER-
TROPOSPHERIC OUTFLOW EMANATING FROM STY 16W TO THE NORTHWEST. UPPER-
LEVEL OUTFLOW IS SUBSEQUENTLY RESTRICTED IN THE NORTHWEST QUADRANT
OF 18W, BUT GOOD ELSEWHERE, WITH A ROBUST OUTFLOW CHANNEL TO THE
EAST. TS 18W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE DEEP-
LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 18W IS FORECAST TO TRACK WEST-NORTHWESTWARD THEN
NORTHWESTWARD THROUGH TAU 72. THE STR IS FORECAST TO GRADUALLY ERODE
AS A SHORTWAVE TROUGH APPROACHES FROM CHINA. DYNAMIC MODEL GUIDANCE
IS IN GOOD AGREEMENT THROUGH TAU 72, SO THERE IS FAIR CONFIDENCE IN
THIS PORTION OF THE FORECAST TRACK. ATMOSPHERIC CONDITIONS ARE
FORECAST TO IMPROVE IN THE COMING DAYS, AS STY 16W MOVES FURTHER
AWAY TO THE WEST, ALLOWING FOR AN IMPROVEMENT IN THE POLEWARD
OUTFLOW. A PERIOD OF RAPID INTENSIFICATION IS POSSIBLE FROM TAU 24
TO 48, IF THE TUTT CELL TO THE NORTH OF TS 18W BECOMES ORIENTED TO
ALLOW FOR A POLEWARD OUTFLOW CHANNEL.
C. AFTER TAU 72, TD 18W IS FORECAST TO TRACK POLEWARD TOWARD
THE VICINITY OF OKINAWA ALONG THE WESTERN PERIPHERY OF THE STR.
HOWEVER, DYNAMIC MODEL GUIDANCE DIVERGES SIGNIFICANTLY AT THESE
EXTENDED TAUS, WITH DIFFERENCES IN THE TIMING AND DEGREE OF
CURVATURE TOWARD THE NORTH AND NORTHEAST. TS 18W SHOULD REACH PEAK
INTENSITY AROUND TAU 72 TO 96, WHEN INTERACTION WITH THE SHORTWAVE
TROUGH IS FORECAST TO OCCUR. THERE IS LOW CONFIDENCE IN THE JTWC
TRACK FORECAST BEYOND TAU 72.//
NNNN

[1900hurricane]

I've seen several Mets on Twitter already refer to 18W as Rai, which is surprising considering JMA has yet to upgrade as far as I can tell.

[euro6208]

WDPN33 PGTW 121500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (EIGHTEEN)
WARNING NR 04//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 18W (EIGHTEEN), LOCATED APPROXIMATELY 234 NM NORTH
OF FAIS, HAS TRACKED WEST-NORTHWESTWARD AT 13 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 121158Z
MHS 89GHZ MICROWAVE IMAGE SHOWS FLARING CONVECTION NEAR THE LOW-
LEVEL CIRCULATION CENTER (LLCC), WITH THE DEEPEST CONVECTIVE CELL TO
THE SOUTHEAST. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE.
THE CURRENT INTENSITY REMAINS ASSESSED AT 40 KNOTS, USING A BLEND OF
DVORAK ESTIMATES RANGING FROM T1.5 (RJTD) TO T3.0 (PGTW). TS 18W
CONTINUES TO FEEL THE EFFECTS OF THE OUTFLOW OF STY 16W TO ITS
NORTHWEST AND IS SUFFERING THE EFFECTS OF MODERATE VERTICAL WIND
SHEAR (20 TO 25 KNOTS). THUS, THE UPPER-LEVEL OUTFLOW REMAINS
RESTRICTED IN THE NORTHWEST QUADRANT BUT IS GOOD ELSEWHERE. TS 18W
IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 18W IS FORECAST TO TRACK WEST-NORTHWESTWARD THEN
NORTHWESTWARD THROUGH TAU 72. THE STR IS FORECAST TO GRADUALLY ERODE
AS A SHORTWAVE TROUGH APPROACHES FROM THE WEST. DYNAMIC MODEL
GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72, SO THERE IS FAIR
CONFIDENCE IN THIS PORTION OF THE FORECAST TRACK. AS STY 16W MOVES
FURTHER AWAY FROM TS 18W, THE UPPER-LEVEL ENVIRONMENT IS FORECAST TO
IMPROVE, WITH THE VERTICAL WIND SHEAR REDUCING AND A RIDGE BUILDING
OVER THE SYSTEM, WHICH WILL ALLOW FOR STEADY INTENSIFICATION TO
OCCUR, PARTICULARLY BEYOND TAU 24.
C. AFTER TAU 72, TS 18W IS FORECAST TO TRACK POLEWARD TOWARD
THE VICINITY OF OKINAWA ALONG THE WESTERN PERIPHERY OF THE STR AND
INTO A WEAKNESS IN THE STR AXIS INDUCED BY A SHORTWAVE TROUGH.
HOWEVER, DYNAMIC MODEL GUIDANCE DIVERGES SIGNIFICANTLY AT THESE
EXTENDED TAUS, WITH DIFFERENCES IN THE TIMING AND DEGREE OF
CURVATURE TOWARD THE NORTH AND NORTHEAST. TS 18W SHOULD REACH PEAK
INTENSITY AROUND TAU 96, DURING THE POINT OF RECURVATURE. WEAKENING
IS FORECAST TO COMMENCE SHORTLY THEREAFTER DUE TO INTERACTION WITH
THE SHORTWAVE TROUGH. THERE IS LOW CONFIDENCE IN THE JTWC TRACK
FORECAST BEYOND TAU 72.//
NNNN

[euro6208]

Back up to 3.0 from JTWC and KNES ups to 2.5...

[1900hurricane]

I've seen several Mets on Twitter already refer to 18W as Rai, which is surprising considering JMA has yet to upgrade as far as I can tell.

Heh, 19W got Rai, leaving 18W with Malakas.

[euro6208]

The EURO peaks this at 944mb east of Shanghai and slams Western Japan.

GFS has Okinawa is it's sights. 954 mb at landfall...

[euro6208]

Aw that sucks. I wanted this to be Rai not Malakas.

[1900hurricane]

Aw that sucks. I wanted this to be Rai not Malakas.

Yep, same.

JMA sure is taking their sweet time with the 18Z advisory. It makes me think that they're about to upgrade 18W too.

*EDIT: sure enough, JMA is naming it Malakas for 18Z. Their page is acting a little glitchy at the moment, but I'll post the rundown when I can get to it.

[euro6208]

The title says Tropical Storm Meranti...so Cat 5 Meranti has a same twin but weaker?

[1900hurricane]

Here it is!

TS 1616 (Malakas)
Issued at 19:25 UTC, 12 September 2016

<Analysis at 18 UTC, 12 September>
Scale -
Intensity -
Center position N13°35' (13.6°)
E139°30' (139.5°)
Direction and speed of movement WNW 20 km/h (12 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 ALL 170 km (90 NM)

<Forecast for 06 UTC, 13 September>
Intensity -
Center position of probability circle N14°30' (14.5°)
E137°05' (137.1°)
Direction and speed of movement WNW 20 km/h (12 kt)
Central pressure 994 hPa
Maximum wind speed near center 23 m/s (45 kt)
Maximum wind gust speed 35 m/s (65 kt)
Radius of probability circle 70 km (40 NM)

<Forecast for 18 UTC, 13 September>
Intensity -
Center position of probability circle N15°35' (15.6°)
E134°40' (134.7°)
Direction and speed of movement WNW 20 km/h (12 kt)
Central pressure 990 hPa
Maximum wind speed near center 25 m/s (50 kt)
Maximum wind gust speed 35 m/s (70 kt)
Radius of probability circle 110 km (60 NM)

<Forecast for 18 UTC, 14 September>
Intensity Strong
Center position of probability circle N17°55' (17.9°)
E130°30' (130.5°)
Direction and speed of movement WNW 20 km/h (12 kt)
Central pressure 975 hPa
Maximum wind speed near center 35 m/s (65 kt)
Maximum wind gust speed 50 m/s (95 kt)
Radius of probability circle 200 km (110 NM)
Storm warning area ALL 260 km (140 NM)

<Forecast for 18 UTC, 15 September>
Intensity Strong
Center position of probability circle N21°00' (21.0°)
E126°55' (126.9°)
Direction and speed of movement NW 20 km/h (11 kt)
Central pressure 965 hPa
Maximum wind speed near center 40 m/s (75 kt)
Maximum wind gust speed 55 m/s (105 kt)
Radius of probability circle 260 km (140 NM)
Storm warning area ALL 350 km (190 NM)