Wow What A Wind! (may 10th)

[jaiyenjohn]

What the hel_l just blew through chiang mai? All of a sudden a 100mph wind and rain storm just plowed through the city. There are trees down everywhere!

[donna]

youre ok though, jaiyenjohn? no damage?

[davidgtr]

No rain or wind at my house in Santitham.

Must have been one of those violent local storms, you usually get at this time of the year.

The worst city storm that I can remember was "a few years ago" ago when the Bier Stube lost their roof (it ended up in the moat I think) & all the power lines were down on Maneenoparat Rd, the North outside of the moat.

[jaiyenjohn]

Nothing really bad. Half of our jackfruit tree split apart and can now be found on our neighbor's roof, but we were lucky.

Curious if that was local, I'd love to know how something like that happens. The only thing I can compare it to was the one Oklahoma tornado I was in.

Wierd.

[Ulysses G.]

No rain or wind at my house in Santitham.

Must have been one of those violent local storms, you usually get at this time of the year.

The worst city storm that I can remember was "a few years ago" ago when the Bier Stube lost their roof (it ended up in the moat I think) & all the power lines were down on Maneenoparat Rd, the North outside of the moat.

The worst storm that I can remember was in about 1991. I was in the Bier Stube and it sure seemed like the roof was going to fly off, but I don't remember it actually happening.

Are you sure about this? How could I have been here the whole time and missed that?

[Ulysses G.]

By the way, didn't notice any 'big wind" in the Thapae Gate area today.

[jaiyenjohn]

By the way, didn't notice any 'big wind" in the Thapae Gate area today.

I'm actually in the Hang Dong area, I just assumed something that big was city-wide. But if it was localized, as suggested color me impressed... and curious about the meteorological conditions required.

One of my associates experienced it at work near here, and when he got back home to Saraphi it turns out it didn't even so much as sprinkle there at all.

Just curious...

[Tywais]

I'm actually in the Hang Dong area, I just assumed something that big was city-wide. But if it was localized, as suggested color me impressed... and curious about the meteorological conditions required.

Looks to be localized. I just got caught up in it as I was driving home from the university to my house on the canal road. Live close to Hang Dong when it let loose with a driving rain and my car started pulling sideways from the wind. It was about half way from CMU on the canal road when it started. Came down so hard that the water had no time to drain off the road and a couple of close encounters with hydroplaning happened.

[earlofwindermere]

Nothing on the Mae Jo side of town.

[whimsy]

I live near Hillside 4 condo. We had something like you describe about 4pm on TUESDAY. Suddenly huge gusts of wind followed by torrential rain for about 20 mins. As usual when we get big winds, the power went off for a few minutes too.

[davidgtr]

No rain or wind at my house in Santitham.

Must have been one of those violent local storms, you usually get at this time of the year.

The worst city storm that I can remember was "a few years ago" ago when the Bier Stube lost their roof (it ended up in the moat I think) & all the power lines were down on Maneenoparat Rd, the North outside of the moat.

The worst storm that I can remember was in about 1991. I was in the Bier Stube and it sure seemed like the roof was going to fly off, but I don't remember it actually happening.

Are you sure about this? How could I have been here the whole time and missed that?

Spoke to Thip at the Bier Stube this morning & she says it was 8th May, 20 years ago that they lost the entire roof into the moat. This was the first year of the Bier Stube's operations & so maybe a bit before your time, but not quite mine. Now you know. It also means that summer storms have been around for awhile, they are most definitely not new.

[Ajarn]

I'd imagine living on the leeward side of the mountains might have something to do with it.

[lopburi3]

We don't have any mountains here in Bangkok (unless you count the buildings downtown) but we have had several very violent storms this year with horizontal rain and higher winds than I ever remember.

[Ajarn]

We don't have any mountains here in Bangkok (unless you count the buildings downtown) but we have had several very violent storms this year with horizontal rain and higher winds than I ever remember.

Hey, I didn't say it had everything to do with it

[Ulysses G.]

No rain or wind at my house in Santitham.

Must have been one of those violent local storms, you usually get at this time of the year.

The worst city storm that I can remember was "a few years ago" ago when the Bier Stube lost their roof (it ended up in the moat I think) & all the power lines were down on Maneenoparat Rd, the North outside of the moat.

The worst storm that I can remember was in about 1991. I was in the Bier Stube and it sure seemed like the roof was going to fly off, but I don't remember it actually happening.

Are you sure about this? How could I have been here the whole time and missed that?

Spoke to Thip at the Bier Stube this morning & she says it was 8th May, 20 years ago that they lost the entire roof into the moat. This was the first year of the Bier Stube's operations & so maybe a bit before your time, but not quite mine. Now you know. It also means that summer storms have been around for awhile, they are most definitely not new.

It was the "a few years ago" quote that threw me off. 20 years ago would go down as "a long time ago" in my way of thinking.

[davidgtr]

No rain or wind at my house in Santitham.

Must have been one of those violent local storms, you usually get at this time of the year.

The worst city storm that I can remember was "a few years ago" ago when the Bier Stube lost their roof (it ended up in the moat I think) & all the power lines were down on Maneenoparat Rd, the North outside of the moat.

The worst storm that I can remember was in about 1991. I was in the Bier Stube and it sure seemed like the roof was going to fly off, but I don't remember it actually happening.

Are you sure about this? How could I have been here the whole time and missed that?

Spoke to Thip at the Bier Stube this morning & she says it was 8th May, 20 years ago that they lost the entire roof into the moat. This was the first year of the Bier Stube's operations & so maybe a bit before your time, but not quite mine. Now you know. It also means that summer storms have been around for awhile, they are most definitely not new.

It was the "a few years ago" quote that threw me off. 20 years ago would go down as "a long time ago" in my way of thinking.

Yeah well, it's only a few years ago for us old farts, you're still a bit young & "have not been here the whole time" (& neither have I.) Actually I thought it must have been 10-12 years, not 20!

[Ulysses G.]

GTR=Golden Triangle Rider.

Sorry, didn't notice that before. Yes, for you 20 years is only short-time.

Great maps by the way!

[davidgtr]

GTR=Golden Triangle Rider.

Sorry, didn't notice that before. Yes, for you 20 years is only short-time.

Great maps by the way!

Ah yes GTR, you're on the ball at last G.

To be honest, 20+ yrs is a bit more than 1 of your short times, but I cant complaining.

Been thru a few delicate storms myself in that time too, some more than local. (Could also give you a few massage tips....but won't)

Thanks for the map compliments, just wish I could get the other 3 finished that I am working on. Should be 1 or 2 newbies by the end of the year & enough to carry me thru the next tempest if I'm lucky. Cheers. You've got a better bookshop than the ex used to have!

[p1p]

Let's move from Old Farts and return to to winds!

About five years ago we had a short blow at home. Sounded a bit like a large plane taking off and resulted in some nasty damage to our roof and four trees down in our garden.

Our next-door neighbour's beautiful, barely finished teak house was reduced to the foundations and a long trail of broken planks and matchtick-sized pieces of wood spread over a 300+ metre path. (We had to take his housekeeper to hospital as he suffered a broken arm in the wind.)

The blow also picked up a large stand of big bamboo with a 3 metre circumfrence and dropped it 50 metres away on the opposite side of an (untouched) building! It was carried, roots, soil and all leaving a hole where the root-ball used to be.

[jaiyenjohn]

Exactly! This is what I was commenting on in my first post, it was just an amazing amount of wind blowing by with no warning. It was like being in a tornado, but with no funnel cloud, etc.

The same thing happened again here yesterday, but only about 1/4 the intensity. Still the power went off, etc.

Does anyone know what this localized phenomena is called? Where I can get more information? I just find the whole concept fascinating.

[jaiyenjohn]

Well, I did some research and think the phenomena is called a downslope wind storm: here's the info:

http://amsglossary.allenpress.com/glossary...lope-windstorm2

downslope windstorm—A very strong, usually gusty, and occasionally violent wind that blows down the lee slope of a mountain range, often reaching its peak strength near the foot of the mountains and weakening rapidly farther away from the mountains.

Gust speeds in such winds may exceed 50 m s−1 and occasionally strong vortices capable of doing F1 to F2 damage (see Fujita scale) may occur in association with these winds. Such windstorms are most likely to the lee of elongated quasi-two-dimensional mountain ranges and can be distinguished from gap winds, which are confined to within or downstream of notable gaps or breaks in a mountain barrier and are generally weaker and less gusty. Downslope windstorms of great severity require an upstream mountain range having a crest at least roughly 1 km in height above terrain to its lee, and with a steep leeside slope. Meteorological conditions favoring downslope windstorms are strong synoptic-scale flow across the mountain barrier at the level of its crest, with the cross-range component of the flow either decreasing with height or not increasing too rapidly with height above the crest. Also favorable is high static stability at the level of the mountain crest in the flow approaching the mountain range, decreasing with height above. A mean-state critical level in the middle troposphere, where the flow component across the mountain drops to zero and reverses sign, is often very favorable for downslope windstorms. Downslope windstorms can be considered a gravity wave phenomenon in the sense that vertically propagating gravity waves launched by the passage of stable air over high-amplitude terrain become very steep or break, creating an internal region above the mountain that is characterized by turbulence and a lapse rate approaching the dry adiabatic. Such a region restricts the vertical propagation of energy, allowing the flow near the surface of the mountain to accelerate downslope. Downslope windstorms can also be considered hydraulic jump phenomena in which flow becomes supercritical above and to the lee of a mountain barrier. Downslope windstorms are often known by local names in areas where they occur throughout the world (e.g., the bora along the northeastern shore of the Adriatic Sea and the Taku wind along the Gastineau Channel in southeast Alaska).

Here's the fujita scale (these winds get to f1-f2)

Fujita scale—(Also known as the F-scale.) Relates tornado intensity indirectly to structural and/or vegetative damage.

The estimated wind speed is calculated using the following formula: V = 6.30 (F+2)1.5 m s−1. A six-point scale has been developed that corresponds to the following wind-speed estimates:

# F0 (light damage): 18–32 m s−1

# F1 (moderate damage): 33–49 m s−1

# F2 (considerable damage): 50–69 m s−1

# F3 (severe damage): 70–92 m s−1

# F4 (devastating damage): 93–116 m s−1

# F5 (incredible damage):117–142 m s−1.

Although extremely dependent on the design of a structure and the tree type, the following visual characteristics of the damage have been assigned to the F-scale.

# F0 - Some damage to chimneys; branches broken; shallow-rooted trees knocked over.

# F1 - Surface of roofs peeled off; mobile homes pushed off foundations or overturned; moving autos pushed off road.

# F2 - Roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted.

# F3 - Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off ground and thrown.

# F4 - Well-constructed houses leveled; structures with weak foundations blown off; large missiles generated.

# F5 - Strong frame houses lifted off foundations and carried considerable distances; automobile- sized missiles flying through the air for distances in excess of 100 m; trees debarked.