WPAC: CHAN-HOM - Post-Tropical

[euro6208]

Pressure on Guam is 1000mb with partly cloudy skies and no wind...

[cycloneye]

WDPN31 PGTW 032100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHAN-HOM) WARNING
NR 14//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 09W (CHAN-HOM), LOCATED APPROXIMATELY 259 NM
EAST-SOUTHEAST OF ANDERSEN AFB, GUAM HAS TRACKED NORTH-NORTHWESTWARD
AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY SHOWS CENTRAL CONVECTION HAS BEGUN TO
REDEVELOP OVER THE PREVIOUSLY EXPOSED LOW LEVEL CIRCULATION CENTER
(LLCC). A 031828Z SSMIS 91GHZ MICROWAVE IMAGE SHOWS A BROAD LLCC
WITH LIMITED CONVECTION. A 031145Z SCATTEROMETER PASS SHOWED THE
WELL-DEFINED LLCC WITH STRONGER WINDS LOCATED ALONG THE SOUTHERN
PERIPHERY. THE CURRENT POSITION IS BASED ON THE LLCC IN THE EIR LOOP
AND EXTRAPOLATED FROM THE SCATTEROMETER PASS WITH GOOD CONFIDENCE.
THE INITIAL INTENSITY IS BASED ON THE SCATTEROMETER PASS AND AN
ASSESSMENT OF CURRENT INTENSITY ESTIMATES FROM ALL AGENCIES. THE
SYSTEM IS SLOWLY DRIFTING NORTHWARD DUE TO A SOUTHWESTERLY SURGE TO
THE SOUTHEAST IN THE LOW TO MID LEVELS. THE TUTT CELL THAT HAS BEEN
IMPACTING THE CONVECTION OVER THE SYSTEM IS STILL LOCATED TO THE
NORTHEAST OF THE SYSTEM, CAUSING HIGH VERTICAL WIND SHEAR (VWS) AND
SUBSIDENCE ALOFT.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 09W WILL CONTINUE TO DRIFT NORTH TO NORTHWESTWARD OVER THE
NEXT 12 HOURS WHILE THE TUTT SLOWLY RETREATS TO THE NORTHEAST WHICH
IS PREVENTING THE SUB-TROPICAL RIDGE (STR) FROM BUILDING IN NORTH OF
THE SYSTEM AND ASSUMING STEERING. DURING THIS TIME EXPECT SLOW
DEVELOPMENT AS VWS SLOWLY REDUCES. BEYOND TAU 12, AS THE TUTT
FURTHER RETREATS AND THE STR BUILDS, TS 09W WILL BEGIN TO ACCELERATE
TO THE NORTHWEST. THE SYSTEM WILL FURTHER INTENSIFY AS OUTFLOW
IMPROVES, VWS REDUCES, AND SEA SURFACE TEMPERATURES (SSTS) REMAIN
FAVORABLE.
C. IN THE EXTENDED TAUS, TS CHAN-HOM WILL CONTINUE TO TRACK
NORTHWESTWARD AND FURTHER INTENSIFY AS VWS AND OUTFLOW REMAIN
FAVORABLE. TOWARDS THE END OF THE FORECAST PERIOD, SSTS AND OCEAN
HEAT CONTENT REDUCE BEGINNING A SLIGHT WEAKENING TREND. DYNAMIC
MODEL GUIDANCE IS IN GOOD AGREEMENT ON THE OVERALL TRACK; HOWEVER,
DUE TO THE MODELS HANDLING OF THE TUTT INTERACTION, THERE REMAINS
LOW CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN

[Yellow Evan]

Would an increase in intensity from 35 to 40 knt require more than just an area of TS winds.

If not, why is that a requirement if you're only gonna enforce it with 35 knt systems?

It needs a well-defined low-level circulation center with organized convection. Wind alone won't cut it.

That's the case for all tropical cyclones. Why leave a system with an area of 35 knt (per A/RapidScat) winds a TD if it already is a TC?

[wxman57]

That's the case for all tropical cyclones. Why leave a system with an area of 35 knt (per A/RapidScat) winds a TD if it already is a TC?

You misunderstand me, I'm saying that if it a former TS now lacks a well-defined LLC and organized convection then it wouldn't qualify for classification as a tropical cyclone (TD or TS).

It's still hard to locate a well-defined LLC on IR imagery, but we just got a couple of visible shots. I can tell that it definitely is not where the JTWC put it at 21Z (11.5N/148.7E). It may be reforming to the north near 12.8N/148E near that burst of convection, but I can also see a weak LLC well to the west associated with the squalls that were sheared away from Chan-hom last night. That may be a MLC, though.

ASCAT descending pass is heading toward Chan-hom's area now. May hit it within the next hour.

Here's a visible satellite. Nothing near JTWC's estimated position. Of course, their estimate was made before the first visible satellite, so you can't fault them on their estimate.

[Alyono]

not sure this is really Chan-Hom. An argument can be made that Chan-Hom dissipated and a new TC formed from that disturbance that was east of Chan-Hom yesterday

[xtyphooncyclonex]

Restrengthening and organizing back... Maybe a STS/TY later tonight or dawn

[TropicalAnalystwx13]

Not sure where talk of two separate entities are coming from. The western convective mass southwest of Guam is the mass the low-level circulation separated and moved northeast from last night. Now, convection is developing with the center east of Guam as the environment becomes increasingly favorable. Is it stretched southwest-to-northeast between the two separate areas of convection? Yes. Are there two different discernible centers? I don't think so.

[euro6208]

000
WTPQ81 PGUM 040719
HLSPQ1

URGENT - IMMEDIATE BROADCAST REQUESTED
TROPICAL CYCLONE LOCAL STATEMENT
NATIONAL WEATHER SERVICE TIYAN GU
515 PM CHST SAT JUL 4 2015

...TROPICAL STORM CHAN-HOM SLOWLY MOVING NORTH-NORTHWEST...

.NEW INFORMATION...
A TYPHOON WARNING IS IN EFFECT FOR TINIAN AND SAIPAN.
A TROPICAL STORM WARNING IS IN EFFECT FOR ROTA.

.AREAS AFFECTED...
THIS LOCAL STATEMENT PROVIDES INFORMATION AND RECOMMENDED ACTIONS
FOR PEOPLE IN THE MARIANA ISLANDS AND SURROUNDING WATERS.

.WATCHES/WARNINGS...
A TYPHOON WARNING IS NOW IN EFFECT FOR SAIPAN AND TINIAN AND THEIR
COASTAL WATERS. TYPHOON CONDITIONS...INCLUDING WINDS OF 74 MPH OR
MORE...ARE EXPECTED WITHIN 24 HOURS.

A TROPICAL STORM WARNING IS NOW IN EFFECT FOR ROTA AND THEIR COASTAL
WATERS. TROPICAL STORM CONDITIONS...INCLUDING WINDS OF 39 TO 73
MPH...ARE EXPECTED WITHIN 24 HOURS.

A TYPHOON WATCH REMAINS IN EFFECT FOR GUAM AND ROTA AND ADJACENT
COASTAL WATERS. TYPHOON CONDITIONS...INCLUDING WINDS OF 74 MPH OR
MORE...ARE POSSIBLE WITHIN 48 HOURS.

A FLASH FLOOD WATCH IS IN EFFECT FOR GUAM...ROTA...TINIAN AND SAIPAN.

.STORM INFORMATION...
AT 100 PM CHST...0300 UTC...THE CENTER OF TROPICAL STORM CHAN-HOM
WAS LOCATED NEAR LATITUDE 12.7 DEGREES NORTH AND LONGITUDE 148.2
DEGREES EAST. THIS IS ABOUT 240 MILES EAST-SOUTHEAST OF GUAM...
225 MILES EAST-SOUTHEAST OF ROTA...AND 235 MILES SOUTHEAST OF SAIPAN
AND TINIAN. MAXIMUM SUSTAINED WINDS REMAIN AT 50 MPH. CHAN-HOM IS
MOVING NORTH-NORTHWEST AT 10 MPH.

.SITUATION OVERVIEW...
TROPICAL STORM CHAN-HOM IS EXPECTED TO TURN NORTHWEST TONIGHT AND
BECOME A TYPHOON BEFORE IT PASSES NEAR SAIPAN SUNDAY AFTERNOON OR
EVENING.

.PRECAUTIONARY/PREPAREDNESS ACTIONS...
PRECAUTIONARY/PREPAREDNESS ACTIONS...

PUT YOUR DISASTER PREPAREDNESS PLAN INTO ACTION. MAKE SURE YOU
HAVE ENOUGH FOOD AND WATER FOR A FEW DAYS...AS WELL AS FUEL FOR
VEHICLES AND GENERATORS. PREPARE YOUR PROPERTY FOR TROPICAL STORM
OR TYPHOON CONDITIONS...POSSIBLE SUNDAY OR SUNDAY NIGHT. THE
CURRENT FORECAST BRINGS THE CENTER OF CHAN-HOM NEAR SAIPAN SUNDAY
AFTERNOON OR EVENING...BUT UNCERTAINTY REMAINS IN THE FORECAST
TRACK AND INTENSITY. THUS...EVEN THOUGH SAIPAN...TINIAN AND ROTA
ARE THE ONLY LOCATIONS UNDER A WARNING...RESIDENTS OF GUAM SHOULD
STILL PAY CLOSE ATTENTION TO THE LATEST FORECASTS AND ADVISORIES
AND CONTINUE PREPARATIONS. THERE IS STILL TIME FOR UNFORESEEN
CHANGES THAT COULD PUT GUAM AT GREATER RISK.

FOR MARINERS...SAFELY SECURE YOUR CRAFT AND MAKE PLANS TO LEAVE
IT FOR ADEQUATE LAND BASED SHELTER. SMALL CRAFT SHOULD RETURN TO
PORT.

CLOSELY MONITOR NOAA WEATHER RADIO OR OTHER LOCAL NEWS OUTLETS
FOR OFFICIAL STORM INFORMATION. BECAUSE SMALL ADJUSTMENTS IN
FORECAST TRACK ARE EXPECTED...LISTEN FOR UPDATED FORECAST
INFORMATION.

&&

.NEXT UPDATE...
THE NEXT LOCAL STATEMENT WILL BE ISSUED BY THE NATIONAL WEATHER
SERVICE IN TIYAN AROUND 9 PM CHST...OR SOONER IF CONDITIONS
WARRANT.

GUZ001-PMZ151-041445-
/O.CON.PGUM.TY.A.0003.000000T0000Z-000000T0000Z/
GUAM-GUAM COASTAL WATERS-
515 PM CHST SAT JUL 4 2015

...TYPHOON WATCH REMAINS IN EFFECT...

...PRECAUTIONARY/PREPAREDNESS ACTIONS...
PRECAUTIONARY/PREPAREDNESS ACTIONS...

CONTINUE PREPARATIONS FOR THE POSSIBILITY OF TROPICAL STORM
CONDITIONS IF CHAN-HOM'S TRACK CHANGES. LISTEN FOR UPDATED FORECASTS
AND STATEMENTS AND POSSIBLE WARNINGS.

&&

...WINDS AND SEAS...
TROPICAL STORM FORCE WINDS ARE POSSIBLE SUNDAY AFTERNOON OR EVENING.
WINDS WILL SUBSIDE LATE SUNDAY NIGHT AND MONDAY.

SEAS OF 10 TO 12 FEET ARE EXPECTED THROUGH MONDAY.

...STORM SURGE AND STORM TIDE...
HAZARDOUS SURF OF 10 TO 12 FEET TONIGHT MAY BUILD TO 11 TO 14 FEET
SUNDAY AFTERNOON.

...INLAND FLOODING...
A FLASH FLOOD WATCH IS IN EFFECT. RAINFALL OF 6 INCHES OR MORE IS
POSSIBLE THROUGH SUNDAY NIGHT.

$$

GUZ002-PMZ152-041445-
/O.NEW.PGUM.TR.W.0004.150704T0631Z-000000T0000Z/
/O.CON.PGUM.TY.A.0003.000000T0000Z-000000T0000Z/
ROTA-ROTA COASTAL WATERS-
515 PM CHST SAT JUL 4 2015

...A TROPICAL STORM WARNING IS IN EFFECT...
...A TYPHOON WATCH REMAINS IN EFFECT...

...PRECAUTIONARY/PREPAREDNESS ACTIONS...
PRECAUTIONARY/PREPAREDNESS ACTIONS...

CONTINUE PREPARATIONS FOR TROPICAL STORM CONDITIONS...EXPECTED BY SUNDAY
AFTERNOON. FOLLOW INSTRUCTIONS ISSUED BY YOUR LOCAL EMERGENCY MANAGEMENT
OFFICIALS. LISTEN FOR UPDATED FORECASTS...STATEMENTS OR WARNINGS.

&&

...WINDS AND SEAS...
TROPICAL STORM FORCE WINDS ARE EXPECTED ON SUNDAY...AND TYPHOON FORCE
WINDS ARE POSSIBLE LATE SUNDAY IF CHAN-HOM SHIFTS ITS TRACK SOUTHWARD.
WINDS WILL SUBSIDE LATE SUNDAY NIGHT AND MONDAY.

SEAS OF 10 TO 12 FEET WILL BUILD AS CHAN-HOM NEARS AND COULD REACH UP
TO 15 FEET SUNDAY AFTERNOON AND EVENING AS CHAN-HOM PASSES.

...STORM SURGE AND STORM TIDE...
HAZARDOUS SURF OF 10 TO 12 FEET TODAY MAY BUILD TO DANGEROUS
LEVELS OF 17 TO 22 FEET SUNDAY EVENING ESPECIALLY ACROSS TINIAN
AND SAIPAN. DANGEROUS SURF WILL SUBSIDE BY MONDAY MORNING.

COASTAL INUNDATION OF 1 TO 2 FEET IS EXPECTED ALONG EAST FACING
SHORES AS CHAN-HOM APPROACHES.

...INLAND FLOODING...
A FLASH FLOOD WATCH IS IN EFFECT. RAINFALL OF 6 INCHES OR MORE IS
POSSIBLE THROUGH SUNDAY NIGHT.

$$

GUZ003-004-PMZ153-154-041445-
/O.NEW.PGUM.TY.W.0003.000000T0000Z-000000T0000Z/
TINIAN-SAIPAN-TINIAN COASTAL WATERS-SAIPAN COASTAL WATERS-
515 PM CHST SAT JUL 4 2015

...TYPHOON WARNING IS IN EFFECT...

...PRECAUTIONARY/PREPAREDNESS ACTIONS...
PRECAUTIONARY/PREPAREDNESS ACTIONS...

COMPLETE PREPARATIONS FOR TYPHOON CONDITIONS...EXPECTED BY SUNDAY
AFTERNOON. FOLLOW INSTRUCTIONS ISSUED BY YOUR LOCAL EMERGENCY MANAGEMENT
OFFICIALS. LISTEN FOR UPDATED FORECASTS...STATEMENTS OR WARNINGS.

&&

...WINDS AND SEAS...
TROPICAL STORM FORCE WINDS ARE EXPECTED ON SUNDAY...AND TYPHOON FORCE
WINDS ARE LIKELY LATE SUNDAY AS CHAN-HOM PASSES NEAR SAIPAN. WINDS WILL
SUBSIDE LATE SUNDAY NIGHT AND MONDAY.

SEAS OF 10 TO 12 FEET WILL BUILD AS CHAN-HOM NEARS AND COULD REACH UP
TO 20 FEET SUNDAY AFTERNOON NEAR THE CENTER.

...STORM SURGE AND STORM TIDE...
HAZARDOUS SURF OF 10 TO 12 FEET WILL BUILD TO DANGEROUS LEVELS OF 15 TO
20 FEET SUNDAY AFTERNOON AND EVENING. DANGEROUS SURF WILL SUBSIDE BY
MONDAY MORNING.

COASTAL INUNDATION OF 2 TO 3 FEET IS EXPECTED ALONG EAST FACING SHORES
AS CHAN-HOM APPROACHES.

...INLAND FLOODING...
A FLASH FLOOD WATCH IS IN EFFECT. RAINFALL OF 6 INCHES OR MORE IS
POSSIBLE THROUGH SUNDAY NIGHT.

$$

[euro6208]

000
WTPQ31 PGUM 040954
TCPPQ1

BULLETIN
TROPICAL STORM CHAN-HOM (09W) ADVISORY NUMBER 16
NATIONAL WEATHER SERVICE TIYAN GU WP092015
800 PM CHST SAT JUL 4 2015

...TROPICAL STORM CHAN-HOM HEADING TOWARD THE MARIANAS...

CHANGES WITH THIS ADVISORY
--------------------------
NO CHANGES.

WATCHES AND WARNINGS
--------------------
A TYPHOON WARNING REMAINS IN EFFECT FOR SAIPAN AND TINIAN AND THEIR
COASTAL WATERS. TYPHOON CONDITIONS...INCLUDING WINDS OF 74 MPH OR
MORE...ARE EXPECTED WITHIN 24 HOURS.

A TROPICAL STORM WARNING REMAINS IN EFFECT FOR ROTA AND THEIR
COASTAL WATERS. TROPICAL STORM CONDITIONS...INCLUDING WINDS OF 39
TO 73 MPH...ARE EXPECTED WITHIN 24 HOURS.

A TYPHOON WATCH REMAINS IN EFFECT FOR GUAM AND ROTA AND ADJACENT
COASTAL WATERS.

SUMMARY OF 700 PM CHST...0900 UTC...INFORMATION
-----------------------------------------------
LOCATION...13.5N 147.2E

ABOUT 140 MILES EAST-SOUTHEAST OF ROTA
ABOUT 150 MILES SOUTHEAST OF SAIPAN AND TINIAN
ABOUT 165 MILES EAST OF GUAM

MAXIMUM SUSTAINED WINDS...50 MPH
PRESENT MOVEMENT...NORTHWEST...310 DEGREES AT 13 MPH

DISCUSSION AND OUTLOOK
----------------------
AT 700 PM CHST...0900 UTC...THE CENTER OF TROPICAL STORM CHAN-HOM
WAS LOCATED BY SATELLITE AND THE GUAM RADAR NEAR LATITUDE 13.5
DEGREES NORTH AND LONGITUDE 147.2 DEGREES EAST. LATEST RADAR IMAGERY
INDICATES THAT THE CENTER MAY HAVE SLOWED SLIGHTLY AS IT PASSES EAST
OF GUAM. HOWEVER...CHAN-HOM IS EXPECTED TO RESUME MOVING NORTHWEST
LATER TONIGHT. CHAN-HOM IS EXPECTED TO CONTINUE IN THIS DIRECTION
ALTHOUGH SOME ERRATIC MOTION IS STILL POSSIBLE OVER THE NEXT 12 TO
24 HOURS.

MAXIMUM SUSTAINED WINDS REMAIN AT 50 MPH. TROPICAL STORM FORCE WINDS
EXTEND OUTWARD UP TO 100 MILES FROM THE CENTER...PRIMARILY IN THE
STRONG CONVECTION OUT AWAY FROM THE CENTER. CHAN-HOM IS EXPECTED
TO INTENSIFY SLOWLY THE NEXT COUPLE OF DAYS. CHAN-HOM COULD BECOME A
TYPHOON AGAIN SUNDAY NIGHT OR MONDAY MORNING WEST OF THE MARIANAS.

NEXT ADVISORY
-------------
AN INTERMEDIATE ADVISORY WILL BE ISSUED BY THE NATIONAL WEATHER
SERVICE AT 1100 PM THIS EVENING FOLLOWED BY THE NEXT SCHEDULED
ADVISORY AT 200 AM EARLY SUNDAY MORNING.

$$

W. AYDLETT/EDSON

[euro6208]

Convection increasing...

[euro6208]

000
WGMY60 PGUM 040545
FFAMY

URGENT - IMMEDIATE BROADCAST REQUESTED
FLOOD WATCH
NATIONAL WEATHER SERVICE TIYAN GU
345 PM CHST SAT JUL 4 2015

.HEAVY RAIN ASSOCIATED WITH TROPICAL STORM CHAN-HOM IS EXPECTED
TO PRODUCE HEAVY RAINFALL ACROSS THE MARIANA ISLANDS. THIS MAY
OVERWHELM LOCAL DRAINAGE SYSTEMS AND THE CAPACITY OF THE SOIL TO
ABSORB MOISTURE.

GUZ001>004-042045-
/O.NEW.PGUM.FF.A.0002.150704T0545Z-150706T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
GUAM-ROTA-TINIAN-SAIPAN-
345 PM CHST SAT JUL 4 2015

...FLASH FLOOD WATCH IN EFFECT THROUGH MONDAY AFTERNOON...

THE NATIONAL WEATHER SERVICE IN TIYAN HAS ISSUED A

* FLASH FLOOD WATCH FOR GUAM...ROTA...TINIAN AND SAIPAN.

* THROUGH MONDAY AFTERNOON

* TROPICAL STORM CHAN-HOM MAY BRING 6 INCHES OR MORE OF RAIN TO
THE MARIANAS TONIGHT THROUGH MONDAY.

* ROADS IN POOR DRAINAGE AREAS COULD BECOME IMPASSABLE. HOUSES
IN LOW-LYING AREAS AND CLOSE TO STREAMS AND RIVERS COULD START
TAKING ON WATER.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED. IF ANY STORM DRAINS NEAR
YOU ARE CLOGGED WITH DEBRIS...CLEAN THEM OUT TO MINIMIZE THE
IMPACTS OF ANY FLOODING. IF LIVE NEAR STREAMS AND RIVERS...PAY
CLOSE ATTENTION TO THE WATER LEVELS.

&&

$$

MIDDLEBROOKE

[euro6208]

You can see the LLC clearly on the radar with little to no rain for the islands especially Guam. Hard to believe there is even a tropical storm just east of us...



This matches with JTWC's latest 3 hour position which shows it tracking more westerly towards Guam...

[xtyphooncyclonex]

TS 1509 (CHAN-HOM)
Issued at 12:50 UTC, 4 July 2015

<Analyses at 04/12 UTC>
Scale Large
Intensity -
Center position N13°35'(13.6°)
E146°20'(146.3°)
Direction and speed of movement NW 30km/h(15kt)
Central pressure 990hPa
Maximum sustained wind speed 23m/s(45kt)
Maximum wind gust speed 35m/s(65kt)
Area of 30kt winds or more ALL500km(270NM)

<Forecast for 05/00 UTC>
Intensity -
Center position of probability circle N14°35'(14.6°)
E145°05'(145.1°)
Direction and speed of movement NW 15km/h(8kt)
Central pressure 985hPa
Maximum wind speed near the center 25m/s(50kt)
Maximum wind gust speed 35m/s(70kt)
Radius of probability circle 90km(50NM)

<Forecast for 05/12 UTC>
Intensity -
Center position of probability circle N15°35'(15.6°)
E143°50'(143.8°)
Direction and speed of movement NW 15km/h(8kt)
Central pressure 980hPa
Maximum wind speed near the center 30m/s(55kt)
Maximum wind gust speed 40m/s(80kt)
Radius of probability circle 130km(70NM)
Storm warning area ALL200km(110NM)

<Forecast for 06/12 UTC>
Intensity Strong
Center position of probability circle N17°30'(17.5°)
E140°25'(140.4°)
Direction and speed of movement WNW 15km/h(9kt)
Central pressure 965hPa
Maximum wind speed near the center 35m/s(70kt)
Maximum wind gust speed 50m/s(100kt)
Radius of probability circle 200km(110NM)
Storm warning area ALL310km(170NM)

<Forecast for 07/12 UTC>
Intensity Very Strong
Center position of probability circle N19°55'(19.9°)
E136°20'(136.3°)
Direction and speed of movement WNW 20km/h(11kt)
Central pressure 950hPa
Maximum wind speed near the center 45m/s(85kt)
Maximum wind gust speed 60m/s(120kt)
Radius of probability circle 390km(210NM)
Storm warning area ALL540km(290NM)

[xtyphooncyclonex]

I'm thinking of a typhoon tomorrow. Looks like it's about to bomb out

[wxman57]

The ASCAT image below is from 2333Z yesterday. It went right over the top of Chan-hom and found two disorganized centers (more like an elongated trof), as I had posted last evening. Neither appeared to be organized enough for TC classification at that time, but the northern center was the stronger of the two. The ascending pass of the ASCAT satellite probably passed very close to Chan-hom around 12Z but that image hasn't been posted yet (http://www.knmi.nl/scatterometer/ascat_b_osi_co_prod/ascat_app.cgi). It should be posted any minute.

It's clear that the weak circulation to the southwest has dissipated, but I can't tell the status of the northern center with IR imagery. Convection is increasing east of Guam so I suspect that center will continue to organize as pressures fall in the region. There's less competition out there today. Plotted the 6Z GFS and 00Z Euro atop one another and they're dead-on in agreement with each timestep through landfall near Shanghai next Friday. But just because they're in nearly perfect agreement doesn't mean they're correct. Chan-hom could make final landfall anywhere from just north of Taiwan to southern Japan.

Note that microwave imagery suggests that the center is north of 14N.

[xtyphooncyclonex]

09W CHAN-HOM 150704 1200 13.5N 146.1E WPAC 40 993

[wxman57]

Unfortunately, ASCAT missed Chan-hom's possible center. It caught the western third of what looks like a broad circulation.

[cycloneye]

Okinawa may be in the bullseye.



WDPN31 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHAN-HOM) WARNING
NR 17//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 09W (CHAN-HOM), LOCATED APPROXIMATELY 64 NM
SOUTHEAST OF ROTA, HAS TRACKED WEST-NORTHWESTWARD AT 10 KNOTS
OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS
A BROAD LOW-LEVEL CIRCULATION CENTER (LLCC) WITH FRAGMENTED
DEEP CONVECTIVE BANDING WRAPPING LOOSELY INTO A POORLY-ORGANIZED
CENTER. THE BROAD NATURE OF THE LLCC IS EVIDENT IN A 041125Z METOP-A
IMAGE, WHICH SHOWS SHALLOW CURVED BANDING. RECENT RADAR IMAGERY
DEPICTS CURVED BANDING OVER THE WESTERN SEMI-CIRCLE OF THE LLCC AND
SUPPORTS THE CURRENT POSITION AND RECENT TRACK MOTION WITH FAIR
CONFIDENCE. THE CURRENT INTENSITY IS ASSESSED AT 40 KNOTS BASED ON
DVORAK ESTIMATES RANGING FROM T2.5 TO T3.0 (35 TO 45 KNOTS) AND
RECENT SCATTEROMETER DATA SHOWING ONLY 20 TO 25 KNOT WINDS OVER THE
WESTERN SEMI-CIRCLE OF THE LLCC. OVERALL, THE SYSTEM CONTINUES TO
STRUGGLE TO ORGANIZE DESPITE IMPROVING POLEWARD OUTFLOW ASSOCIATED
WITH THE TUTT CELL POSITIONED NEAR 27N 153E. TS 09W IS TRACKING WEST-
NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF THE DEEP-LAYERED SUB-
TROPICAL RIDGE (STR).
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE. HOWEVER, THE FORECAST TRACK HAS BEEN
SHIFTED CLOSER TO GUAM DUE TO CURRENT POSITION ADJUSTMENTS BASED ON
RADAR IMAGERY.
B. TS 09W WILL CONTINUE TO ACCELERATE ON A WEST-NORTHWESTWARD TO
NORTHWESTWARD TRAJECTORY UNDER THE STEERING INFLUENCE OF THE STR
ENTRENCHED TO THE NORTH ASSUMING IT STRENGTHENS. HOWEVER, IT IS
POSSIBLE THAT THE SYSTEM MAY TRACK MORE WESTWARD AS A WEAKER SYSTEM
UNDER THE LOW-LEVEL EASTERLY STEERING INFLUENCE. THEREFORE, THERE IS
HIGH UNCERTAINTY IN THE EXACT TRACK ACROSS THE NORTHERN MARIANA
ISLANDS. THIS IS FURTHER EXACERBATED BY THE BROAD, ILL-DEFINED
NATURE OF THE LLCC AND CHALLENGES IN LOCATING THE PRECISE CENTER.
DYNAMIC GUIDANCE IS IN FAIR AGREEMENT WITH A 75 NM SPREAD IN
SOLUTIONS AT TAU 24, WITH GFDN ON THE SOUTHERN EDGE OF THE AIDS
ENVELOPE, POSITIONED JUST SOUTH OF SAIPAN. BASED ON RECENT IMAGERY,
IT IS UNLIKELY THAT TS 09W WILL STRENGTHEN SIGNIFICANTLY AT CPA,
THEREFORE, MAXIMUM SUSTAINED WINDS ARE EXPECTED TO RANGE FROM 35 TO
40 KNOTS AS THE SYSTEM PASSES THE NORTHERN MARIANA ISLANDS. TS 09W
IS FORECAST TO SLOWLY INTENSIFY THROUGH TAU 24 DUE TO MARGINALLY
FAVORABLE CONDITIONS AND IMPROVING OUTFLOW. AFTER TRACKING ACROSS
THE NORTHERN MARIANA ISLANDS, TS 09W SHOULD INTENSIFY MORE RAPIDLY
UNDER FAVORABLE CONDITIONS TO A PEAK INTENSITY OF 110 KNOTS BY TAU
72.
C. BEYOND TAU 72, TS 09W WILL CONTINUE TO TRACK NORTHWESTWARD
UNDER THE INFLUENCE OF THE DOMINANT STEERING STR. VWS AND UPPER
LEVEL DIVERGENCE WILL REMAIN FAVORABLE THROUGH THE END OF THE
FORECAST PERIOD; HOWEVER, SEA SURFACE TEMPERATURES AND OCEAN HEAT
CONTENT WILL DECREASE CAUSING A SLOW DOWN IN INTENSIFICATION AND
THEN A WEAKENING PHASE BEYOND TAU 96. WITH THE EXCEPTION OF NAVGEM,
DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGHOUT THE FORECAST
PERIOD WITH SOME DIVERGENCE BEYOND TAU 96. NAVGEM TRACKS THE SYSTEM
ERRONEOUSLY NORTHWARD, THROUGH THE STR, TOWARD THE KOREAN PENINSULA.
OVERALL LOW CONFIDENCE REMAINS DUE TO THE AFOREMENTIONED POSITIONAL
UNCERTAINTY AND INCREASING UNCERTAINTY IN THE TRACK NEAR OKINAWA AS
THE SYSTEM APPROACHES THE SOUTHWEST PERIPHERY OF THE STR.//
NNNN

[xtyphooncyclonex]

Shifted farther west, agreeing with the EC. Going more west than forecast

[Dave C]

That's a tight little vortex east of Guam on radar heading towards Rota. Rota should start reporting in about 4 hrs hopefully!