Climate Effects of a Different Geography in the U.S. (snowy, hot)

[Patricius Maximus]

With my knowledge of climate as well as how geography affects climate, as well as my knowledge of the climates of the United States, I have thought of a hypothetical scenario where the geography of the States east of the Rockies would be vastly different, and I have wondered what sort of effects it would have on climate. I'm sure that some of the regulars here may have some insight beyond what I've thought of.

Given my climate preferences, which are much more amenable to something like Anchorage, Alaska or Kiruna, Sweden than anywhere in the U.S. east of the Rockies and south of Lake Huron, I know that higher altitude would make the climates of the East colder, which would be better for me . There's also the matter of the warm and humid air masses that come from the Gulf of Mexico; to me, a hater of warmth and humidity, they're a menace, and I'd like to dispose of that sort of airmass.

To that end, I've constructed a hypothetical rough map of the U.S. where the present Appalachians are raised to an altitude similar to the Rockies today. I've also graded the Appalachians into a new and very tall mountain range that straddles the entire Gulf Coast region. I've also raised the remainder of the south to an altitude similar to the highlands of the Southeast, and created several minor ranges and a new great lake.



So, let's say God, a member of the Q Continuum, or some other (near)-omnipotent entity made this new geography come into being, while at the same time there being no damage from the topograhic alterations. What would the effect be on cities in the United States and Canada?

[dxnerd86]

Raising the height of the Appalachians would block cold and snowy airmasses from the NW US/Canada! I'd say the BosWash region would then become another PNW with mostly rain and little snow. The Mississippi Range would block heat in summer so it would be a very mild climate along the east coast.

Does the Gulf Stream still exist? This is responsible for elevated humidity levels in summer- so if it is still there, you'd still get warm and humid summers despite the Mississippi Range. In this case BosWash would be similar to southern New South Wales in summer but cooler in winter.

The Mid West on the other hand with its elevated plateau would be interesting, a lot colder that's for sure, though you'd get local effects with all those secondary mountain ranges. The little mountain range downwind of the great lake would be a snow lovers' dream!

As for the Florida Range, the effects would be similar to the Great Dividing Range near Cairns here in Australia. Mount Bellenden Ker receives 327 inches/8312 mm per year!

Mount Bellenden Ker - Wikipedia, the free encyclopedia

[Superluminal]

Interesting scenario...

My initial thoughts:

Given the Rockies height of the "new" Appalachians and given that high mountain ranges attract low pressure systems in summer (think Himalayas) - and bearing in mind that there are also high plateaus behind these new ranges:

- A tropical climate, with a strong monsoonal regime ("tropical savanna" or tropical wet and dry) will prevail over the now narrow Gulf coast as well as the southeast, and perhaps as far north as Washington DC. (extremely wet summers and extremely arid "winters")
- NYC and Philadelphia will now likely have the climate of present-day north Florida/southern Georgia or perhaps Hong Kong or Rio de Janeiro, again with a rainfall distribution that is strongly monsoonal
- most of the New England coastline will become firmly subtropical, with the possible exception of Maine
- Meanwhile north and west of those coastal mountains, the plateaus will likely have a steppe or dry tundra climate as they will now be heavily reliant on polar low pressure systems for any precipitation - this is assuming the present day Rockies still exist as they are - blocking a westerly flow

In this scenario, I think it will be unlikely that the interior will be very snowy - a cold desert climate is more likely.

[Patricius Maximus]

Originally Posted by dxnerd86

Does the Gulf Stream still exist? This is responsible for elevated humidity levels in summer- so if it is still there, you'd still get warm and humid summers despite the Mississippi Range. In this case BosWash would be similar to southern New South Wales in summer but cooler in winter.

Yes, the Gulf Stream still exists in the scenario I created. I figured the summers would still be humid on the coastline. I was trying to figure what sort of an effect it would have on the interior, like Tennessee, Illionois, Arkansas, etc. Wouldn't the humidity from the oceans be blocked? I imagine it would and that would lead to less humidity in summertime. I also imagine temperatures would be cooler due to the higher elevation.

The Mid West on the other hand with its elevated plateau would be interesting, a lot colder that's for sure, though you'd get local effects with all those secondary mountain ranges. The little mountain range downwind of the great lake would be a snow lovers' dream!

I figured. I put that mountain range in there just for that purpose . Since most of the warmth in winter there originates from the Gulf region, and any other warmth that could be generated in Arkansas or Mississippi wouldn't be there due to the elevation I figured it would make it much colder - cold airmasses wouldn't be blocked, so the new average would be closer to a current cold snap in those regions.

As for the Florida Range, the effects would be similar to the Great Dividing Range near Cairns here in Australia. Mount Bellenden Ker receives 327 inches/8312 mm per year!

Wow. That much? Its height is over 5000 feet, more than I envisioned a peak in the Florida Range to be. Also the lowlands near Cairns are a lot more tropical than Florida is, so I imagine that a 2000-3000 foot peak may have some sort of rainy highland climate?

And speaking of rain I have an additional inquiry - what do you all think the climate of the southern slopes of the Mississippi Range would be like? Would it be rainy with all that heat and humidity "condensing" as the elevation increases?

Originally Posted by Superluminal

Interesting scenario...

My initial thoughts:

Given the Rockies height of the "new" Appalachians and given that high mountain ranges attract low pressure systems in summer (think Himalayas) - and bearing in mind that there are also high plateaus behind these new ranges:

- A tropical climate, with a strong monsoonal regime ("tropical savanna" or tropical wet and dry) will prevail over the now narrow Gulf coast as well as the southeast, and perhaps as far north as Washington DC. (extremely wet summers and extremely arid "winters")
- NYC and Philadelphia will now likely have the climate of present-day north Florida/southern Georgia or perhaps Hong Kong or Rio de Janeiro, again with a rainfall distribution that is strongly monsoonal
- most of the New England coastline will become firmly subtropical, with the possible exception of Maine

That's interesting, and there would likely be significant warming, at least in winter, on the coast. However I read somewhere else that the monsoon in East Asia is driven more by the size of the continent than the Himalayas. The Rockies are quite high and cold air doesn't seem to have much of a problem penetrating to the Pacific coast (albeit with a lot of warming), so maybe the East Coast would be more like another PacNW? It would still be warmer than the West Coast due to the Gulf Stream (vs. the West Coast's cold current), but maybe not tropical .

- Meanwhile north and west of those coastal mountains, the plateaus will likely have a steppe or dry tundra climate as they will now be heavily reliant on polar low pressure systems for any precipitation - this is assuming the present day Rockies still exist as they are - blocking a westerly flow

In this scenario, I think it will be unlikely that the interior will be very snowy - a cold desert climate is more likely.

I figured that most of the interior would have an arid climate, especially the flat plateau portions. However, what do you think the interior mountains would be like? Many ranges in Wyoming and as far east as the Black Hills don't seem to have much trouble squeezing out enough Pacific moisture to be fully non-arid, and they're east of most of the Rocky Mountains.

In this scenario the only moisture source left for places like Kentucky and Kansas is leftover Pacific moisture. Clipper systems that only have Pacific moisture available seem to still be able to give the flatlands some amount of moisture as it is, at least enough to have a decent amount of snow and not be bone-dry. Of course if that's the only source of moisture it would be a lot drier than what it is now.

I imagine the west slopes of the new interior mountains would squeeze out a lot of moisture from these Clippers (that would presumably still be present) via orographic lift, and these places would have similar or perhaps somewhat less snow than the ranges in Wyoming and the Black Hills do (which would still be snowy by American standards). Even the driest arctic air can be really moistened up by a great lake, and this is borne out by the driest of Clippers producing copious amounts of snow in the snowbelt areas, so long as the air is cold enough and it's windy enough. With the great lake I created the effect would be similar, and the mountains downwind of it would enhance the moisture content further.

[deneb78]

For your preferences Patricius, another feature you can add is to eliminate the Gulf Stream entirely down the East coast and make the cold Labrador extend all the way past Florida into the Caribbean similar to how the Humboldt current cools the west coast of South America all the way up to the equator. Imagine the sight of an iceberg off the coast of Miami

[nei]

Originally Posted by deneb78

For your preferences Patricius, another feature you can add is to eliminate the Gulf Stream entirely down the East coast and make the cold Labrador extend all the way past Florida into the Caribbean similar to how the Humboldt current cools the west coast of South America all the way up to the equator. Imagine the sight of an iceberg off the coast of Miami

Don't. Let's not change too much. Also might be physically impossible with the position of oceans and continents.

[CairoCanadian]

I'm thinking your inland area would still get pretty hot though maybe not humid - I'm thinking Turpan type climates.

Given your preferences I'd say make your lake enormous ( like a quadruple-Superior ) and the nudge it up westward of one of your mountain ranges. Somewhere on those slopes would be your town!

As for me I suspect your east coast would be more favorable to me than the current one. Probably still too continental in the north, but I'm thinking somewhat more like east coast Japan as one gets into the south-east.

[nei]

I'm going to go with the coast first since that's where I live (or at least on the coast of the Appalachians). The most important thing to take into account is that the largest source of moisture in the eastern half of the county is no the Atlantic Ocean, it's the Gulf of Mexico.

The coast east of the Appalachians will become much drier. However, there are still coastal Atlantic storms. Desert-like conditions are unlikely, but precipitation will still be much lower. The Atlantic is cooler than the Gulf of Mexico, so the East Coast should have somewhat less humid summers, at least north of 37°N or so.

A cold Northwest airflow is possible in the winter. But coming over the mountains, its moisture should be sucked out and warmed in its descent. Cold-ish winter temperatures will still possible in Philly through Bosotn but extreme cold snaps much less likely. The Atlantic isn't all that warm in the winter.

[dunno what to put here]

Originally Posted by nei

Don't. Let's not change too much. Also might be physically impossible with the position of oceans and continents.

Well, when the Europeans settled in N America they wrote about frozen waters off the coast of North Carolina, and that was only during the 'little Ice Age'.

[Patricius Maximus]

Originally Posted by deneb78

For your preferences Patricius, another feature you can add is to eliminate the Gulf Stream entirely down the East coast and make the cold Labrador extend all the way past Florida into the Caribbean similar to how the Humboldt current cools the west coast of South America all the way up to the equator. Imagine the sight of an iceberg off the coast of Miami

I agree with Nei; let's keep the Gulf Stream for this scenario. However, perhaps we could do another scenario later on with the Gulf Stream eliminated (with the current topography or the new one), and that would be a drastic improvement for the winter fans of this board.

Originally Posted by CairoCanadian

I'm thinking your inland area would still get pretty hot though maybe not humid - I'm thinking Turpan type climates.

It may be quite continental, but keep in mind that my plateau would probably be closer to Tibet than Turpan, seeing as Turpan is below sea level in a depression . At 4000 feet in elevation the summers would be quite different, though they'd probably still be a bit toasty.

Given your preferences I'd say make your lake enormous ( like a quadruple-Superior ) and the nudge it up westward of one of your mountain ranges. Somewhere on those slopes would be your town!

That would be a good thing for snow, and perhaps I should have done that. The mountain range would really be snowy. However, I didn't want to make my scenario too blatantly biased towards my own preference, and a lake quadruple the size of Lake Superior may entail too much maritime moderation; even places downwind of it as it is are moderated, though a higher altitude would mitigate that somewhat.

As for me I suspect your east coast would be more favorable to me than the current one. Probably still too continental in the north, but I'm thinking somewhat more like east coast Japan as one gets into the south-east.

It does seem that the East Coast would become warmer. Perhaps for most people involved my new geography is an improvement .

Originally Posted by dunno what to put here

Well, when the Europeans settled in N America they wrote about frozen waters off the coast of North Carolina, and that was only during the 'little Ice Age'.

That's true, although I imagine even during the Little Ice Age that wasn't "normal conditions"; it was likely similar to the Chesapeake Bay freezing over in modern times, i.e. not normal but it does occur in some years.

It may not be physically possible (or plausable) given current continent configuration for the Labrador Current to go down to Florida; however it already does go down part of the east coast of the continent even though there usually is a warm current featured at that position if I'm not mistaken. There's also the matter of Gulf Stream shutdowns, which likely have occurred in the past. Plus according to one hypothesis during Heinrich Events, which have occurred during glacial periods, the ocean currents were reconfigured and the Gulf Stream flipped and became a cold current.

So from what I gather a cold current or at least a cessation of the warm current seems to be feasible. Of course that does not factor into this scenario.

And in Nei's assessment the winter weather the East Coast gets now would be hogged by the western Appalachians, since they would suck out the moisture and get the cold air as well coming from the arctic. Chinook winds are something I hadn't though of. The West Coast doesn't get them because of the prevailing wind flow but places east of the Rockies do, and I imagine that would hold true for our new Appalachians which would be Rockies-like.

If Chinook winds were to be commonplace on the new East Coast, then conditions, especially in winter, would be warmer and drier than the Pacific Northwest, though as Nei pointed out the East Coast would still have a good chance of being cool in winter. From what I gather the East Coast may have a climate that is generally warm(er) and dry(er), with chinook winds and prevailing mild weather being interrupted by nor'easters bringing in moist air from the Atlantic.

If that's the case, then would the eastern parts of the Appalachians have similarities to the Front Range of the Rockies? When a storm is on an analogous track to a nor'easter they can get blasted with snow as the moist air meets the upslope lift. They're at a higher elevation, and is thus cooler and wetter than the rest of the High Plains, despite being on the east slope and receiving warm dry downsloping air often. So we could have a situation where places like central Pennsylvania and the Poconos have a climate resembling Denver only with more maritime moderation .

In any case, I think I've started a somewhat interesting discussion for a change. It's certainly more stimulating than the hot/cold battles, the subtropics debate, and those "rate the climate" threads .

And I just thought of something: there were some enormous lakes during the closing stages of the last glacial period as the continental ice sheets melted. Perhaps one of these, like Lake Agassiz, could have had a very intense and wide lake-effect snowbelt.