Ngày Quốc tế Giảm nhẹ thiên tai 2019

Bài phát biểu của Bà Akiko Fujii, Phó trưởng Ban giảm thiểu rủi ro tăng cường chống chịu thiên tai, Phó Giám đốc Quốc gia UNDP, Việt Nam, tại Cần Thơ

Theo Chỉ số Rủi ro Thiên tai Toàn cầu 2018, Việt Nam là một trong 10 nước phải chịu tác động nhiều nhất của các sự kiện thời tiết cực đoan gây tổn thất.

The Beaufort Wind Scale (extended)

The Beaufort Wind Force Scale currently in use was developed by Admiral Francis Beaufort in 1805. The initial scale was from 0 to 12 only and they described qualitatively the sea conditions without defining quantitatively the wind speed. It was extended in 1946 to include Forces 13 to 17, and they are normally used in adverse weather conditions, e.g. tropical cyclones.

Beaufort Number	Description used by HKO	General Description	Wind Speed			TC strength	Land conditions	Sea conditions	Wave Height		Image
			knots	km/h	m/s				m	ft
0	Calm (無風)	Calm	0	0-1	0-0.2	(N/A)	Calm. Smoke rises vertically.	Flat.	0	0
1	Light (輕微)	Light air	1-3	2-6	0.3-1.5		Wind motion visible in smoke.	Ripples without crests.	0.1	0.33
2		Light breeze	4-6	7-11	1.6-3.3		Wind felt on exposed skin. Leaves rustle.	Small wavelets. Crests of glassy appearance, not breaking.	0.2	0.66
3	Moderate (和緩)	Gentle breeze	7-10	12-19	3.4-5.4		Leaves and smaller twigs in constant motion.	Large wavelets. Crests begin to break; scattered whitecaps.	0.6	2
4		Moderate breeze	11-15	20-29	5.5-7.9		Dust and loose paper raised. Small branches begin to move.	Small waves.	1	3.3
5	Fresh (清勁)	Fresh breeze	16-21	30-39	8.0-10.7	LPA	Smaller trees sway.	Moderate (1.2 m) longer waves. Some foam and spray.	2	6.6
6	Strong (強風)	Strong breeze	22-27	40-50	10.8-13.8	TD	Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult.	Large waves with foam crests and some spray.	3	9.9
7		Near gale	28-33	51-62	13.9-17.1		Whole trees in motion. Effort needed to walk against the wind.	Sea heaps up and foam begins to streak.	4	13.1
8	Gale (烈風)	Gale	34-40	63-75	17.2-20.7	TS	Twigs broken from trees. Cars veer on road.	Moderately high waves with breaking crests forming spindrift. Streaks of foam.	5.5	18
9		Severe gale	41-47	76-87	20.8-24.4		Light structure damage.	High waves (2.75 m) with dense foam. Wave crests start to roll over. Considerable spray.	7	23
10	Storm (暴風)	Storm	48-55	88-103	24.5-28.4	STS	Trees uprooted. Considerable structural damage.	Very high waves. The sea surface is white and there is considerable tumbling. Visibility is reduced.	9	29.5
11		Violent storm	56-63	104-117	28.5-32.5		Widespread structural damage.	Exceptionally high waves.	11.5	37.7
12	Hurricane (颶風)	Hurricane	64-71/ 64+	118-132/ 118+	32.6-36.6/ 32.6+	TY CAT. 1	Considerable and widespread damage to structures.	Huge waves. Air filled with foam and spray. Sea completely white with driving spray. Visibility greatly reduced.	14+	46+
13	(Not used by HKO)	(Not used except Taiwan and China)	72-80	133-149	36.7-41.3		Not generally seen on land. Catastrophic damage otherwise.
14			81-89	150-166	41.4-46.1	TY CAT. 2
15			90-99	167-183	46.2-50.8
16			100-108	184-201	50.9-55.8	TY CAT. 3 & above
17			109+	202+	55.9+

Source of the images (last column): http://www.stormfax.com/beaufort.htm

BoM's tropical cyclone track forecast

This graphical product provides information about the movement and intensity of a tropical cyclone, as well as showing the areas likely to experience its effects.

This version of the video uses an example from Queensland

Which scenario for TY. Hagupit after entering East Vietnam sea?

This post will summary some of the scenarios  of TY. Hagupit track after entering East Vietnam Sea. In 114 TCs in the IBTraCS data set lies within 1.5 degrees of TY. Hagupit location, there are 18 TCs that are active between 23th November to 23th December, and 15 TCs that have similar intensity with current intensity of TY. Hagupit (55kts). Especially, there are only two tropical cyclones which are active in the same period and similar intensity with Hagupit. They are TY. Manny (1993) and TY. Axel (1994).
Let's have a look on the best tracks of Manny and Axel below

Best track of TY. Axel (December 1994)

Best track of TY. Manny (December 1993)

Both Typhoons downgraded quickly after making landfall and crossing Phillipines and entering East Vietnam sea.
As we are now at the end of the TC season, there is not many chance for a TC to intensify when moving over East Vietnam sea. Hapupit is not an exemption. It should dissipate very soon and very likely to dissipate over the water area.

Kalmaegi track's probability forecast 06Z 15Sep

Typhoon Rammasun hits the Philippines

Authorities said at least 10 people had been killed by the storm.

Strong winds knocked out power and forced thousands of people to evacuate as Typhoon Rammasun hit the central Philippines.
The typhoon, also known as Glenda, struck the main island of Luzon with gusts of up to 185km/h (115 mph).

Millions without power
Town halls had been converted into shelters and evacuees had also been taken to schools and gymnasiums.
"Trees are starting to fall down and everything is just rain and wind," eyewitness Zhey Anzures told the BBC from a Manila suburb.
"We are also just beside a construction site and the cranes are really rotating because of the strong winds."
Manila Electric Company said 2.3 million of its customers were without electricity.

The Philippines is hit by around 20 major storms a year. Typhoon Rammasun is the first to make landfall this year after the rainy season began in June.
Typhoon Haiyan, which devastated the country last year, killed more than 6,000 people and was said to be one of the worst storms on record.

Which Tropical Cyclones Are Similar to Typhoon Rammasun

Here is the two candidates:
1. Typhoon Elsie, October 1989.
Formed higher, also gained typhoon intensity (Vmax >= 64kts) when made landfall in Luzon island, Philippine but after passing longitude of 115E, Elsie has weaken and made landfall about 17-18N of Vietnam with tropical depression intensity.

Typh. Elsie is similar to typh. Rammasun but seem to get weaker after passing 115 degree East

2. Typhoon Angela, October 1995
Formed lower and further to 145 degree East, gained typhoon intensity when passing 135E and kept intensifying and begin to degrade after longitude of 113E. Angela was downgraded and completely dissipated when moving into Bac Bo gulf.

3. What's my forecast for typh. Rammasun?
- Rammasun will continue its way straight forward into Bac Bo gulf after passing Hainnan island while keep its intensity at severe tropical storm or weak typhoon. It means that Rammasun will move further north and stronger than its two cousins.
- The difference in month between Rammasun and its cousins also suggest that Rammasun will go further north.
... much more information need to be justified but impossible with those two track maps.