Asteroids, and other Natural Disasters in Pittsburgh?

[WILWRadio]

The following scenario is probably the best example of how a gigantic wave could wipe out some inland areas of the country. However, I'd say it is unlikely to happen in WPA because the hills are old and small and the rivers are the only potential source of water to create a tidal wave.

World's Biggest Tsunami | 1720 feet-tall - Lituya Bay, Alaska

The following scenarios post a major threat to any coastal area of the country. However, the odds of these happening any time soon are slim.

Tidal Waves Called Threat to East Coast - The New York Times

BBC NEWS | Science/Nature | Tidal wave threat 'over-hyped'

[Hopes]

My husband saw a comet blow up in the sky last week.

[Hopes]

Originally Posted by dugdogmaster

Flooding; It happens, buy flood insurance.

Great advice on flood insurance. Buy it even if your house isn't in a flood zone. Sometimes Pittsburgh floods due to water runoff when the ground is saturated and houses in high areas can and do flood.

Originally Posted by dugdogmaster

Do not ever drive into flooded roadways, people!

It makes me crazy that people do this during the routine floods, but they're downright insane when it's a flash flood.

The most important advice is ABANDON the car and run uphill. There's no time to save a vehicle in a flash flood.

(OP: The only true flash flood that occurred here in my lifetime was in the 80s. Although flash floods are fairly rare here, there's always a risk.)

[aveojohn]

Originally Posted by Hopes

My husband saw a comet blow up in the sky last week.

Maybe a meteorite, not a comet.

[ditchdigger]

Originally Posted by Hopes

(OP: The only true flash flood that occurred here in my lifetime was in the 80s. Although flash floods are fairly rare here, there's always a risk.)

Wrong.

This comes directly from the National Weather Service Glossary.

Flash Flood A rapid and extreme flow of high water into a normally dry area, or a rapid water level rise in a stream or creek above a predetermined flood level, beginning within six hours of the causative event (e.g., intense rainfall, dam failure, ice jam). However, the actual time threshold may vary in different parts of the country. Ongoing flooding can intensify to flash flooding in cases where intense rainfall results in a rapid surge of rising flood waters.

We have lots of narrow valleys with small streams running through them. Any one of those streams is a potential location for a flash flood, and most of them have experienced flash flooding at one time or another.

Here's the sort of guidance the NWS uses in determining whether to issue a forcast that mentions flash flooding. This is for today. At times when the ground is saturated from earlier rainfalls, the values can be dramatically lower:

ZONE FLASH FLOOD GUIDANCE
NATIONAL WEATHER SERVICE
OHIO RIVER FORECAST CENTER...WILMINGTON OH
716 PM EST SUN NOV 1 2009

.B CIN 20091101 Z DH18/DC200911020016 /DUE/PPHCF/PPTCF/PPQCF/PPKCF/PPDCF
:
: AVERAGE RAINFALL IN INCHES NEEDED TO BEGIN FLOODING
: STEEP TERRAIN CAN GREATLY REDUCE APPARENT INDEX
:IDENT 1HR 3HR 6HR 12HR 24HR ZONE NAME
:======= ==== ==== ==== ==== ==== ====================
PAZ021 1.5/ 2.1/ 2.5/ 3.5/ 4.7 :ALLEGHENY CO
PAZ022 1.5/ 2.1/ 2.3/ 3.2/ 4.2 :ARMSTRONG CO
PAZ020 1.4/ 2.0/ 2.3/ 3.2/ 4.2 :BEAVER CO
PAZ014 1.4/ 1.9/ 2.1/ 2.8/ 3.7 :BUTLER CO
PAZ024 1.5/ 1.9/ 2.1/ 2.7/ 3.5 :CAMBRIA CO
PAZ015 1.4/ 2.0/ 2.3/ 3.2/ 4.2 :CLARION CO

etc...

Source: National Weather Service Text Product Display

You can see that for most locations, even an inch and a half in one hour is enough to cause concern about flash flooding. That's a lot of rain in an hour, but in a summer thunderstorm downpour, that's not a lot of rain to get in an hour, if you get my drift.

I'm not sure which flood in the 80s you're referring to, or where you were to experience it, but out in the hills, they happen often.

(And I'm not picking on you, Hopes. It's just that I think it's an important enough subject to be sure the terminology is understood by everybody reading this. To your credit, your advice about not driving through flood waters is correct. It doesn't take much to float a car...)

[Fiddlehead]

[quote=ditchdigger;11450639]

You can see that for most locations, even an inch and a half in one hour is enough to cause concern about flash flooding. That's a lot of rain in an hour, but in a summer thunderstorm downpour, that's not a lot of rain to get in an hour, if you get my drift.

quote]

Yea, I agree that rain falling on saturated ground can pile up fast. In my 45 years of existance, I have been in or near at least 3 100 year return floods. So, I treat all streams with respect, and have no desire to build my house next to them.

[hempfield mania]

There was a lot of flash flooding from that round of bad T-storms just this past June. I know, it happened right on my street and I was helping neighbors clean out their basements and garages that lived a little lower than me down the street. Our street went from dry to raging with over 18" of water flowing down it in a little over a half an hour. Damage, luckily, was minimal in the grand scheme of things but it was a flash flood by definition and you wouldn't be driving a car through it, that is for sure.

[Fiddlehead]

Originally Posted by hempfield mania

There was a lot of flash flooding from that round of bad T-storms just this past June. I know, it happened right on my street and I was helping neighbors clean out their basements and garages that lived a little lower than me down the street. Our street went from dry to raging with over 18" of water flowing down it in a little over a half an hour. Damage, luckily, was minimal in the grand scheme of things but it was a flash flood by definition and you wouldn't be driving a car through it, that is for sure.

Wow! That sounds scary. I have studied rivers much of my life, and I give them room. Not sure what you do when your street becomes a river!

As an aside, there is a Hempfield Township there? Seems like you would be invaded by hippies with a name like that. ....

[dugdogmaster]

Originally Posted by Fiddlehead

As an aside, there is a Hempfield Township there? Seems like you would be invaded by hippies with a name like that. ....

There's two of them, in fact. One right near Pittsburgh, and one further north near where I live.

I might ad, the one further north lives up to its name. I believe this might have already been discussed though in a previous post.