WPAC: TRAMI - Post-Tropical

[Hayabusa]

Large ensemble spread anywhere from Japan to PH


TCFA 9Z


WTPN21 PGTW 200900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
180 NM EITHER SIDE OF A LINE FROM 12.8N 146.5E TO 16.0N 136.9E
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 15 TO 20 KNOTS. METSAT
IMAGERY AT 200800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 12.9N 146.1E. THE SYSTEM IS MOVING WESTWARD AT 07 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 92W) PREVIOUSLY LOCATED
NEAR 11.6N 144.7E, IS NOW LOCATED NEAR 12.9N 146.1E, APPROXIMATELY
90 NM EAST-SOUTHEAST OF ANDERSEN AFB, GUAM. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY AND A 200518Z SSMI 85GHZ MICROWAVE PASS SHOW A
CONSOLIDATING LOW LEVEL CIRCULATION (LLC) WITH PERSISTENT DEEP
CONVECTION. THIS LLC IS EMBEDDED WITHIN A BROAD MONSOON DEPRESSION
WITH STRONGER WINDS LOCATED OVER THE EASTERN SEMICIRCLE. THE RADAR
LOOP FROM ANDERSEN AFB, GUAM SHOWS IMPROVED CONVECTIVE BANDING
WRAPPING INTO A WELL DEFINED MIDLEVEL (NEAR 7000 FT) CIRCULATION
CENTER. SURFACE OBSERVATIONS FROM ANDERSEN AFB (PGUA) INDICATE
EASTERLY WINDS AT 10 KNOTS WHILE SHIP OBSERVATIONS IN THE VICINITY
INDICATE SOUTHEASTERLY WINDS AT 21 KNOTS. THE DISTURBANCE IS
CURRENTLY LOCATED IN AN AREA OF EXCELLENT POLEWARD UPPER LEVEL
OUTFLOW, LOW VERTICAL WIND SHEAR (5-10 KNOTS), AND WARM SEA SURFACE
TEMPERATURES (28-30 CELSIUS). GLOBAL MODELS ARE IN AGREEMENT THAT
THE SYSTEM WILL CONTINUE TRACKING TO THE WEST-NORTHWEST OVER THE
NEXT SEVERAL DAYS WITH INTENSIFICATION TO WARNING STATUS LIKELY
AFTER IT PASSES TO THE WEST OF GUAM, HOWEVER, DUE TO THE MONSOON
DEPRESSION CHARACTERISTICS THERE IS CONSIDERABLE UNCERTAINTY IN THE
INITIAL POSITION OF THE SYSTEM. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1003 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
210900Z.//
NNNN

[Hayabusa]

Euro 00Z op run now makes it stronger


GFS 00Z ensemble

[1900hurricane]

I'd be interested in seeing some ASCAT data on the system since it appears the possible developing center and the convection might not be quite lining up on microwave imagery.

[euro6208]

[euro6208]

Flash Flood Watch issued for Guam and the Marianas.

FLOOD WATCH
NATIONAL WEATHER SERVICE TIYAN GU
716 PM ChST Thu Sep 20 2018

...HEAVY RAINS THROUGH THIS WEEKEND WILL CREATE A RISK OF
FLOODING...

.A DEVELOPING CIRCULATION PASSING NEAR GUAM WILL CREATE NUMEROUS
TO FREQUENT SHOWERS OVER THE MARIANAS THROUGH THIS WEEKEND. THE
SOIL IS ALREADY SATURATED DUE TO HEAVY RAINS FROM TYPHOON
MANGKHUT LAST WEEK, SO MOST OF THE RAINS THIS WEEKEND WILL BE
RUNOFF AND ADD TO FLOODING PROBLEMS.

GUZ001>004-201730-
/O.CON.PGUM.FF.A.0005.000000T0000Z-180922T2000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
GUAM-ROTA-TINIAN-SAIPAN-
716 PM ChST Thu Sep 20 2018

...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH LATE SATURDAY NIGHT...

THE FLASH FLOOD WATCH CONTINUES FOR

* GUAM, ROTA, TINIAN AND SAIPAN IN THE MARIANA ISLANDS.

* THROUGH LATE SATURDAY NIGHT

* NUMEROUS TO FREQUENT SHOWERS WILL BE MOSTLY RUNOFF. RAIN
AMOUNTS OF 4 TO 8 INCHES ARE EXPECTED WITH LOCALLY HIGHER
AMOUNTS POSSIBLE.

* POOR DRAINAGE AREAS COULD SEE CLOSED ROADS AND EVEN WATER IN
SOME HOUSES. AVOID MOUNTAINOUS AREAS WHERE FLOODING COULD BE
EVEN FLASHIER.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$

STANKO

[euro6208]

TPPN10 PGTW 201228

A. TROPICAL DISTURBANCE 92W (SE OF GUAM)

B. 20/1200Z

C. 12.70N

D. 145.71E

E. FIVE/HMWRI8

F. T1.5/1.5/D0.5/24HRS STT: S0.0/03HRS

G. IR/EIR

H. REMARKS: 70/PBO ANMTN. CNVCTN WRAPS .35 ON LOG10 SPIRAL
YIELDING A DT OF 1.5. MET AND PT AGREE. DBO DT.

I. ADDITIONAL POSITIONS: NONE


RICHARDSON

[euro6208]

GFS again bottoms this out sub 900... right through the Southern Ryukyu Islands...



HWRF

[euro6208]

Center on radar.

Wind gust on Saipan ...35 knots...

[Hayabusa]

12Z JMA
TROPICAL DEPRESSION 1004 HPA AT 12N 144E WEST 10 KT.

[1900hurricane]

 https://twitter.com/1900hurricane/status/1042786347638042626

[euro6208]

[1900hurricane]

Looks like the center could end up passing pretty close to Rota, probably just a little to the south.

[Hayabusa]

JMA now issuing gale warning



TD
Issued at 19:20 UTC, 20 September 2018

<Analysis at 18 UTC, 20 September>
Scale -
Intensity -
TD
Center position N13°40' (13.7°)
E145°00' (145.0°)
Direction and speed of movement W 15 km/h (9 kt)
Central pressure 1002 hPa
Maximum wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)

<Forecast for 06 UTC, 21 September>
Intensity -
TD
Center position of probability circle N14°00' (14.0°)
E141°55' (141.9°)
Direction and speed of movement W 30 km/h (15 kt)
Central pressure 1002 hPa
Maximum wind speed near center 15 m/s (30 kt)
Maximum wind gust speed 23 m/s (45 kt)
Radius of probability circle 110 km (60 NM)

<Forecast for 18 UTC, 21 September>
Intensity -
Center position of probability circle N14°30' (14.5°)
E139°00' (139.0°)
Direction and speed of movement W 25 km/h (14 kt)
Central pressure 1000 hPa
Maximum 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)

[Hayabusa]

92W INVEST 180920 1800 13.8N 145.1E WPAC 25 1003
JTWC too, it's now 28W from the navy site

[1900hurricane]

The next name on the list is Trami.

[Hayabusa]

1st warning pretty aggressive

[1900hurricane]

EPS members are beginning to tighten up some at least through day 5 before splitting off into two camps. Plenty of intense members.

[euro6208]

Peaks 130 knots.

WDPN31 PGTW 202100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 28W (TWENTYEIGHT)
WARNING NR 01//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 28W (TWENTYEIGHT), LOCATED APPROXIMATELY
13 NM EAST-NORTHEAST OF ANDERSEN AFB, HAS TRACKED NORTHWESTWARD AT
08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY DEPICTS FLARING DEEP CONVECTION NEAR THE LOW LEVEL
CIRCULATION CENTER (LLCC) AND BANDING FEATURES STARTING TO DEVELOP,
ESPECIALLY TO THE SOUTHEAST OF THE LLCC. THE INITIAL POSITION IS
PLACED WITH GOOD CONFIDENCE BASED ON RADAR IMAGERY FROM GUAM AND IS
SUPPORTED BY OBSERVATIONS FROM THE SURROUNDING ISLANDS. THE INITIAL
INTENSITY IS BASED ON THE PGTW AND KNES DVORAK CURRENT INTENSITY
ESTIMATES OF T1.5 (25 KNOTS). ENVIRONMENTAL CONDITIONS FOR TD 28W
ARE GENERALLY FAVORABLE WITH GOOD EQUATORWARD AND POLEWARD OUTFLOW,
LOW TO MODERATE VERTICAL WIND SHEAR, AND WARM SSTS (28-29 CELSIUS).
TD 28W IS CURRENTLY TRACKING ALONG A SOUTHERN EXTENSION OF AN
OTHERWISE EAST-WEST ORIENTED SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST
PHILOSOPHY.
B. BY TAU 24, TD 28W IS FORECAST TO GRADUALLY TURN ONTO A
WESTWARD TRACK AS THE EAST-WEST ORIENTATION OF THE STR BECOMES THE
DOMINANT INFLUENCE ON THE TRACK. THE STR TO THE NORTH WILL MAINTAIN
A GENERALLY WESTWARD TRACK THROUGH TAU 72. DURING THIS PERIOD, THE
ENVIRONMENT REMAINS FAVORABLE AND TD 28W IS EXPECTED TO RAPIDLY
INTENSIFY TO 115 KTS BY TAU 72. THE INTENSITY FORECAST CLOSELY
FOLLOWS THE INTENSITY CONSENSUS, HOWEVER SPREAD IS QUITE LARGE AMONG
THE MEMBERS WITH CTCI (130 KTS) AND COTI (75 KTS) REPRESENTING THE
EXTREMES AT TAU 72. MODEL TRACK GUIDANCE HAS ABOUT 170 NM OF SPREAD
BY TAU 72, THEREFORE CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST
IS FAIR.
C. AFTER TAU 72, AN APPROACHING MID-LATITUDE TROUGH IS EXPECTED
TO CREATE A WEAKNESS IN THE STR AND ALLOW TD 28W TO BEGIN ROTATING
POLEWARD AROUND THE RIDGE AXIS. THE INTENSITY IS EXPECTED TO
CONTINUE TO GRADUALLY INCREASE AS CONDITIONS REMAIN FAVORABLE.
HOWEVER, BY TAU 120 THE JTWC FORECAST INTENSITY IS PLACED ABOVE THE
INTENSITY GUIDANCE BASED ON THE EXPECTATION THAT THE MID-LATITUDE
TROUGH WILL BE JUST WEST OF THE TROPICAL CYCLONE AND AID POLEWARD
OUTFLOW. HOWEVER, IF THE TROUGH PASSES TO THE EAST SOONER, THE
CYCLONE WILL BEGIN TO WEAKEN. DURING THIS PERIOD, MODEL TRACK
GUIDANCE BECOMES MORE UNCERTAIN DUE TO DIFFERENCES IN THE TIMING AND
DEGREE OF RE-CURVATURE AROUND THE STR AXIS. FOR THIS REASON, THERE
IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

A Tropical Storm Watch is now in effect for Rota, Tinian and Saipan.

[euro6208]