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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
Re: Chanchu in cool waters [Re: Unregistered User]
      #65240 - Tue May 16 2006 07:18 AM Attachment (386 downloads)

Yes it is interesting that it is so large...attached a more recent microwave that clearly shows the ERC in progress. Notice the lack of strong convection north of 18N (cooler water). This is hidden pretty well under the CDO.

The timing of this ERC, with such a large outer band of convection, will definitely help to weaken the storm. This structure is interesting considering the transition to ET will start to occur just before landfall (the latest JTWC prog is below). The RMW could be quite large. However the JTWC forecast appears to show the wind radii contracting, so the thought must be that the ERC will start towards completion. But since the strong convection is south of 18N over the next 24 hours significant weakening is likely to occur and it is unclear if this will be able to happen. If it can, this may help the TC maintain more intensity than it would otherwise.

It appears that Hong Kong will start to get some stormy weather from the outer band of convection along the outflow channel before too long, and depending on the track, may remain under that band of convection for some time.

There is very good agreement with both track and intensity models, with all intensity models forecasting weakening to around 90-100 kts in 24 hours.

JTWC warning #31 drops the winds down to 110 kts and weakening at the same rate as in the previous warning.

As the storm approaches tomorrow it can be observed on Hong Kong radar:

http://www.hko.gov.hk/wxinfo/radars/radar.htm

Excepts from the most recent JTWC prog (a lot of good info in this one):

B. TY 02W IS TRACKING POLEWARD ALONG THE WESTERN PERIPHERY OF A MID-LEVEL STEERING RIDGE CENTERED EAST OF TAIWAN. UPSTREAM MID-LATITUDE TROUGHING IS FORECAST TO AMPLIFY SLIGHTLY AS A SERIES OF SMALLER PERTURBATIONS TRACK OVER THE NORTHERN BAY OF BENGAL AND NORTHERN INDOCHINA. ADDITIONALLY, A WESTWARD EXTENSION OF THE STEERING RIDGE SHOULD REMAIN IN PLACE TO THE NORTHEAST OF TY 02W THROUGH TAU 24. THE RESULTING FLOW WILL INDUCE A NORTHWARD TRACK INITIALLY, FOLLOWED BY A SHIFT TOWARD THE NORTH-NORTHEAST AFTER TAU 24 AS THE TROUGH MOVES EASTWARD AND RIDGING EAST OF TY 02W WEAKENS. THE STORM WILL BECOME EMBEDDED WITHIN THE MIDLATITUDE WESTERLIES BY TAU 36 AND BEGIN extratropical TRANSITION (XT) WHILE APPROACHING THE COAST OF SOUTHERN CHINA. THE SYSTEM IS EXPECTED TO MAKE LANDFALL EAST OF HONG KONG AROUND TAU 36 AND COMPLETE XT BY TAU 72. WITH THE EXCEPTION OF AN EASTERN (COAMPS) AND WESTERN (TCLAPS) OUTLIER, THE REMAINING DYNAMIC AIDS CONSISTING OF NOGAPS, GFDN, AFWA MM5, NCEP GFS, JGSM, JTYM, EGGR, AND WBAR ARE IN GOOD AGREEMENT WITH THIS SCENARIO.

C. ALTHOUGH TY 02W REMAINS OVER FAVORABLE SEA SURFACE TEMPERATURES AND MAINTAINS GOOD ANTICYCLONIC OUTFLOW, THE SYSTEM IS EXPECTED TO WEAKEN AS MORE STABLE LOW LEVEL AIR IS FUNNELED THROUGH THE TAIWAN STRAIT AND INTO THE NORTHERN SOUTH CHINA SEA. THE STORM WILL WEAKEN RAPIDLY AFTER TAU 24 AS IT TRAVERSES LOWER SEA SURFACE TEMPERATURES, INTERACTS WITH LAND, AND UNDERGOES XT.

D. CURRENT WIND RADII ARE BASED ON A 152234Z QUIKSCAT PASS. FORECAST WIND RADII ARE BASED UPON CLIMATOLOGY FOR AN AVERGE- TO LARGE-SIZED SYSTEM, WITH SOME MODIFICATION FOR XT AT TAU 36.


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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
Re: Chanchu in cool waters [Re: Margie]
      #65241 - Tue May 16 2006 10:05 AM Attachment (377 downloads)

The outer eyewall has consolidated and is contracting rapidly (SSMIS pass attached). There is virtually no convection left besides the two concentric eyewalls...rather unusual.

The small eyewall is still intact and what is further has finally cleared out on IR.

--------------------
Katrina's Surge: http://www.wunderground.com/hurricane/Katrinas_surge_contents.asp


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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
Re: Chanchu in cool waters [Re: Margie]
      #65242 - Tue May 16 2006 10:17 AM Attachment (418 downloads)

Quikscat ascending pass from within the past half hour attached. If I am reading this correctly, there are still winds of 110 kts in the center (I counted several), and 100 kt winds in the outer eyewall.

--------------------
Katrina's Surge: http://www.wunderground.com/hurricane/Katrinas_surge_contents.asp


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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
Re: Chanchu in cool waters [Re: Margie]
      #65243 - Tue May 16 2006 10:18 AM Attachment (383 downloads)

Ditto the descending pass -- very impressive; the winds are uniformly making it down to the surface.

JTWC warning #32 has increased the sustained windspeed at landfall from 80kts to 85kts, and moved the landfall point east, it appears about 50nm. Current winds at 105 kts (I must have read the quikscat wrong). The text notes: "A 161035Z AMSU/B IMAGE REVEALS A SMALL, COMPACT EYE SURROUNDED BY A WEAKENING OUTER EYEWALL."

And the prog notes:

ANIMATED SATELLITE IMAGERY REVEALS A SIGNIFICANT DECREASE IN CONVECTION IN THE NORTHERN QUARDRANTS OF TY 02W OVER THE PAST 12 HOURS. DESPITE FAVORABLE SEA SURFACE TEMPERATURES, STABLE AIR FUNNELED THROUGH THE TAIWAN STRAIT HAS ALREADY STARTED TO WEAKEN TY 02W.


--------------------
Katrina's Surge: http://www.wunderground.com/hurricane/Katrinas_surge_contents.asp


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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
Re: Chanchu in cool waters [Re: Margie]
      #65246 - Tue May 16 2006 05:30 PM Attachment (406 downloads)

Convection has continued to deteriorate. Two microwave passes (attached) show the concentric eyewalls, but the inner eyewall continues to be very well defined, and has cleared out, and this appears to be a steady state, rather than a typical ERC, with very slow overall weakening. JTWC warning #33 maintains the current intensity of 105 kts, and the landfall intensity, and moves the track further east again.

A comment from the warning text is interesting in the sense that it refers to a 'band of convection' rather than an outer eyewall: "A 161825Z TRMM IMAGE REVEALS AN EROSION OF THE NORTHWEST REGION OF THE OUTERMOST BAND OF CONVECTION."

So maybe it had the look of an ERC, but was not considered an ERC, as the inner eyewall never deteriorated. Maybe the moat was simply what was left between the center of convection and the previous spiral bands, that just happened to pull into a second convective ring?

--------------------
Katrina's Surge: http://www.wunderground.com/hurricane/Katrinas_surge_contents.asp


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malt-teaser
Unregistered




Chanchu update [Re: Margie]
      #65252 - Wed May 17 2006 01:18 PM

Officially: Chanchu has left HK without much incident except a couple of sign board damaged outside a gew shops. No one was injured.
Unofficially: Office workers were disappointed their working day was not called off, because the typhoon was not strong enough for the government to issue a level 3 (signal number 8) warning (on a four level scale - 1, 3 8 and 10). Alas!


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malt-teaser
Unregistered




Re: Chanchu update [Re: malt-teaser]
      #65253 - Wed May 17 2006 01:21 PM

For HK's tropical cyclone/storm wanring system: http://www.hko.gov.hk/informtc/tcsignal.htm

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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
Re: Chanchu update [Re: malt-teaser]
      #65259 - Thu May 18 2006 11:22 PM

Quote:

Officially: Chanchu has left HK without much incident except a couple of sign board damaged outside a gew shops. No one was injured.
Unofficially: Office workers were disappointed their working day was not called off, because the typhoon was not strong enough for the government to issue a level 3 (signal number 8) warning (on a four level scale - 1, 3 8 and 10). Alas!




Update on Chanchu:

Typhoon Chanchu kills 21 in China

By Christopher Bodeen in Shanghai (China) | Friday, 19 May , 2006, 08:29

A powerful typhoon pummelled southern China on Thursday, killing at least 21 people and leaving 27 Vietnamese fishermen missing after their boats sank in Chinese waters.

Chanchu, which was downgraded to a tropical storm, has killed more than 60 people in Asia, including 37 last weekend in the Philippines, where it destroyed thousands of homes.

China's official Xinhua News Agency said on Friday that 13 people died from flooding and landslides in the southeastern province of Fujian. Another eight perished in neighbouring Guangdong province.

By early Friday the dramatically weakened storm has moved into the East China Sea.

The storm hit the coast of China early on Thursday, flooding scores of homes and forcing the evacuation of more than 1 million people before weakening to a severe tropical storm.

The missing Vietnamese fishermen were on three boats that sank in Chinese waters, Vietnamese officials said on Thursday. Six other boats with 67 fishermen were able to reach an island and report the sinking of the other vessels. Vietnam asked Chinese authorities to help search for the missing.

Taiwan reported the deaths of two women swept away by floods in the southern region of Pingtung on Wednesday.

In southern Japan, high waves swept away three 17-year-old male students swimming off Hateruma island in the Okinawa chain, leaving one dead and another missing, coast guard spokesman Shoji Kawabata said. The third was rescued.

China said it had moved more than 1 million people to safety in Guangdong and Fujian provinces. The storm bypassed the financial centre of Hong Kong on the Guangdong coast.

Thousands of people evacuated from fishing boats and low-lying areas were staying with relatives, in tents, or in schools and government warehouses, said Zhang, an official of the Chaozhou city government in Guangdong.

Nearly 1,00,000 ships were ordered to return to harbour, Xinhua said.

T C Lee, an official with the Hong Kong Observatory, said Chanchu was the "most intense" typhoon to strike in the South China Sea in May, an early month in the annual cyclone season.

However, the early arrival of the year's first typhoon does not necessarily portend an unusually active storm season, Lee said by telephone.

--------------------
Katrina's Surge: http://www.wunderground.com/hurricane/Katrinas_surge_contents.asp


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