August 2017 PNW Discussion Thread

[Phil]

I wonder what 50"+ of rain in 5 days would do to downtown Seattle and the surrounding communities. As far as I know, such a scenario hasn't actually been modeled yet.

[Front Ranger]

I think that's a fair assessment, however, much of that water drains into reservoirs and rivers that are already at/near capacity after 40"+ of rainfall.

 

There are also at least two watershed tributaries to the S/SW of the city, draining N/NE-ward. So I'm not optimistic, but I would love to be proven wrong here. Especially with the center of convergence poised to move north again later tonight or tomorrow, I don't like the look of this situation over the next 24hrs.

 

Latest GFS certainly isn't good.

 

Hopefully, for those who've seen the worst so far, the storm will continue to drift further east and start to move a bit faster.

[VancouverIslandSouth]

Another warm day up here, 87F but so far not so much as a hint of smoke, much nicer than the heat wave earlier this month. Doesn't look like areas further south have been so lucky.

[Front Ranger]

I wonder what 50"+ of rain in 5 days would do to downtown Seattle and the surrounding communities. As far as I know, such a scenario hasn't actually been modeled yet.

 

It would almost certainly lead to massive mudslides due to all the hills. Probably a much bigger problem than flooding.

 

Of course, you need a tropical system to get such totals.

[TT-SEA]

Another warm day up here, 87F but so far not so much as a hint of smoke, much nicer than the heat wave earlier this month. Doesn't look like areas further south have been so lucky.

 

Today was pretty gross here... very hazy.

[VancouverIslandSouth]

I wonder what 50"+ of rain in 5 days would do to downtown Seattle and the surrounding communities. As far as I know, such a scenario hasn't actually been modeled yet.

 

Pretty crazy that we're talking about rainfall in measurements usually reserved for massive snowstorms. It's virtually impossible to get those sort of totals in this part of the world, we can get prolonged rain events but not with the severe convection needed to for those rapid totals. I've never seen more than 5~6" of rain in a single day here.

[VancouverIslandSouth]

Today was pretty gross here... very hazy.

 

Pretty different from the last go around, I think we took the brunt of the smoke in this area while it was more dispersed further south. That time around it was funneling out of the Fraser Valley. So far this time around those northern smoke sources seem to have fizzled and the largest fires are in the south. I'm sure the smoke will eventually filter up from the south but it won't stick around long.

[stuffradio]

I wonder what 50"+ of rain in 5 days would do to downtown Seattle and the surrounding communities. As far as I know, such a scenario hasn't actually been modeled yet.

Even in my dreariest times of the year, the most I would get is 8-12" of rain in about 1-2 weeks, so having 50" in 5 days would be mind blowing, For me personally, if I was at home, I'd be cut off from being able to go to town due to the valleys that are by me in the roads. I think at the most, the basement or first floor might get flooded, but it wouldn't raise higher than that because the terrain slopes too much close by me, and it goes to a creek maybe 50' down the slope or something. So yes, I would still have so much standing water while it's raining, but it wouldn't be enough for me to get sent to the roof of my house due to life threatening waters, unless the house fell over.

[ShawniganLake]

Pretty different from the last go around, I think we took the brunt of the smoke in this area while it was more dispersed further south. That time around it was funneling out of the Fraser Valley. So far this time around those northern smoke sources seem to have fizzled and the largest fires are in the south. I'm sure the smoke will eventually filter up from the south but it won't stick around long.

I would bet the Chilcotin fires to our north come back to life tomorrow.

[stuffradio]

The new ECMWF weeklies ensembles shows negative 850mb temps and troughing in the west coast for first week of October.

[ShawniganLake]

The new ECMWF weeklies ensembles shows negative 850mb temps and troughing in the west coast for first week of October.

We are due.

[stuffradio]

We are due.

Well it doesn't truly show it until October 5, but still. That's still the first week.

[Phil]

Check out the differences in the boreal winter circulation between the fastest recent global cooling period (1950-1970) versus the fastest recent global warming period (1980-2000).

 

Almosr mirror opposites with respect to PNA/NAM.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/3D22DA73-7EEB-425A-A3A5-28AEECD38469_zpsu4uvihmq.png

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/622E06E8-C178-4C1E-8D70-FB92D81F3176_zpspkbkyaao.png

[Phil]

Nov-Mar 1950-1980, vs Nov-Mar 1980-2010.

 

No coincidence here either. Perfect opposites.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/C7AEB961-2600-40F5-A057-8E7EEEAD133D_zpshberbecd.png

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/E6B4DA8B-5064-46C1-BC22-3F9C04413F31_zpshykvvhqm.png

[TT-SEA]

Very smoky here... despite onshore flow returning now.   Hopefully that will clear out the smoke later today.   The ECMWF shows a decent SW breeze this afternoon across the Seattle area.

[VancouverIslandSouth]

Very smoky here... despite onshore flow returning now.   Hopefully that will clear out the smoke later today.   The ECMWF shows a decent SW breeze this afternoon across the Seattle area.

 

Still clear here, but there is clearly some haze to the south and east this morning. The smoke has been creeping north over the past few days. It's worse for Seattle because there's that large fire to the east and the low level winds often reverse overnight in these heat waves.

 

http://i.imgur.com/I742m7B.png

[TT-SEA]

Still clear here, but there is clearly some haze to the south and east this morning. The smoke has been creeping north over the past few days. It's worse for Seattle because there's that large fire to the east and the low level winds often reverse overnight in these heat waves.

 

http://i.imgur.com/I742m7B.png

 

 

Actually... the smoke over Seattle and Portland has been moving up from southwest Oregon and NW California.   

 

The fires to the east of the Cascade crest have been sending smoke to the NE the last couple days and clearly can be seeing moving to the NE this morning.  That smoke is moving away from us.   

[Phil]

Two stations in Harris County, TX, have recorded over 50" of rainfall from Harvey, with another 8-12"+ possible over the next 24hrs. Good chance someone sees 60"+ by the time it's all said and done.

[Phil]

Some of the preliminary cold season analogs I'm looking at include 1956/57, 1967/68, 1981/82, 1989/90, 1995/96, 2000/01, 2003/04, 2005/06, and 2007/08.

 

This is the SSTA signal I get, for S/O/N and D/J/F.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/60DDB002-2948-4EEF-8A1C-348E6608491E_zpsaztgthqe.png

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/8D242962-84B7-4A56-B008-6BF1D2122112_zpsqf4xlvsq.png

[Phil]

Geopotential height anomalies, by month, depict the coldest weather (relative to average) in October and January, and the warmest weather (relative to average) in September, November and December.

 

September:

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/C6B84B23-1B97-4403-B7BC-D594BD592CEF_zpstsvzlisw.png

 

October:

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/36958577-201D-4C6A-8219-2208138E0A30_zpsd8ynwtqr.png

 

November:

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/8EE3EFC5-6ED5-4BAD-84A8-A3F27466D96B_zpsjefkwzd3.png

 

December:

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/79CC4FD0-B968-4E3E-9EF8-68BBDEB2ED48_zpsx5sy0yyl.png

 

January:

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/A83FB4B8-8FE5-43B3-8C4A-12717D46E0B2_zps4zo0ixmu.png

 

February:

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/6616CCF0-267B-43A2-A348-06F0B545E618_zps3dg0sbbw.png

 

March:

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/9C99B27C-56BD-4693-A488-A7010D64B6F7_zpspwpfzqbh.png

[Front Ranger]

Two stations in Harris County, TX, have recorded over 50" of rainfall from Harvey, with another 8-12"+ possible over the next 24hrs. Good chance someone sees 60"+ by the time it's all said and done.

 

Record amount for a U.S. tropical storm.

[Phil]

The problem is, I'm not sure I believe my own analogs. This would be an insane amount of pattern variance and would typically require a powerful MJO/sub-seasonal instabilities, and there's no scientifically "plausible" method to forecast subseasonal pattern variability 6+ months out, save risky statistical techniques utilizing ENSO/QBO.

 

So, either I'm getting a bunch of noise here, or there is an underlying tendency (during these years) towards a large midwinter wavebreaking event (likely major SSW during late December or early January), that cools the tropical tropopause/decreases aggregate static stability in the tropics, hence igniting the MJO and reshuffling the pattern for J/F/M. If so, then October is fluky here, shaped by wavetrain instabilities as the Asian monsoons undergo their seasonal collapse.

[Front Ranger]

The problem is, I'm not sure I believe my own analogs. This would be an insane amount of pattern variance and would typically require a powerful MJO/sub-seasonal instabilities, and there's no scientifically "plausible" method to forecast subseasonal pattern variability 6+ months out, save risky statistical techniques utilizing ENSO/QBO.

 

So, either I'm getting a bunch of noise here, or there is an underlying tendency (during these years) towards a large midwinter wavebreaking event (likely major SSW during late December or early January), that cools the tropical tropopause/decreases aggregate static stability in the tropics, hence igniting the MJO and reshuffling the pattern for J/F/M. If so, then October is fluky here, shaped by wavetrain instabilities as the Asian monsoons undergo their seasonal collapse.

 

Fortunately, it's still August and we have time for more clues before winter. 

[Front Ranger]

Pretty remarkable that it appears this summer will have 3 top tier heat events. June, August, and now September.

 

Not positive, but I believe this might end up as the only summer where PDX has hit 100+ in three separate months.

[BLI snowman]

Pretty remarkable that it appears this summer will have 3 top tier heat events. June, August, and now September.

 

Not positive, but I believe this might end up as the only summer where PDX has hit 100+ in three separate months.

 

1988 and 1992.

[Phil]

If the PNA reaches +2.5SD's next week, as is modeled, it will join only a handful of years to it in September. These being 1951, 1967, 1976, and 2011.

[Phil]

Interesting to note that all of those years featured developing/maturing -QBOs at the time. It does sort of make sense if, though, if you consider how the -QBO may impact the IO/WPAC convection through the raising/cooling of the tropical tropopause over there.

[wx_statman]

The timing of the upcoming heat wave reminds me of September 2-5, 2003. Little talked-about event, but it's the only time on record that PDX pulled off 3 straight 94's in September. 

[Phil]

Harvey is trying to reconsolidate its low/mid level centers over the Gulf now, which might help Houston proper if it can rob that area of convective uplift as if drifts NE-ward. It's bad news for Louisiana, though.

[TT-SEA]

I think Houston is pretty much done with the rain now.  

[wx_statman]

Public Information Statement
National Weather Service Houston/Galveston TX
1037 AM CDT Tue Aug 29 2017

...The previous record for total rainfall during a tropical cyclone
has been broken...

A preliminary report from one Texas rain gauge has broken the Texas
tropical cyclone rainfall record. Southeast of Houston, Mary`s Creek
at Winding Road reported 49.20 inches in a time period ranging from
12:00 AM CDT August 25 to 9:20 AM CDT August 29. This total is
higher than the previous record of 48 inches set during tropical
cyclone Amelia in 1978 at Medina, Texas. This is a preliminary
report and could potentially increase.

[Front Ranger]

1988 and 1992.

 

Ah. First time for June, August, and September though?

[BLI snowman]

Ah. First time for June, August, and September though?

 

If we do it, sure. Big if though.

[Dave]

The smoke down here is disgusting and is irritating my eyes.  However, I just put my eclipse glasses on so they should be okay again in a few minutes.

[wx_statman]

Will be interesting to see if we can tack on any more 97+ days at PDX. This is already the 3rd straight year with record to near-record totals for 97+ days, after yesterday's 98. 

 

1) 8 days in 1988, 2015

2) 7 days in 1981, 1992, 2016

3) 6 days in 1941, 1967, 1977, 2017 (so far)

[crf450ish]

All these analogs for the fall and early winter are exciting.

[TT-SEA]

The fire just south of Snoqualmie Pass has been explosive today on the visible satellite loop.   Its even showing up on the SEA radar now.

 

Luckily that smoke is blowing to the NNE.  

[wx_statman]

I just noticed how much the smoke at MFR held things down yesterday. Only 95 degrees with visibility

 

http://www.wrh.noaa.gov/mesowest/getobext.php?wfo=pqr&sid=kmfr&num=60&raw=0&banner=off

 

This on a day when RBG hit 102 and 850's at SLE were 24.2C. If anyone has doubts about the effect of smoke on high temperatures (going back to some conversations earlier this month), this is a good example. 

[BLI snowman]

I just noticed how much the smoke at MFR held things down yesterday. Only 95 degrees with visibility

 

http://www.wrh.noaa.gov/mesowest/getobext.php?wfo=pqr&sid=kmfr&num=60&raw=0&banner=off

 

This on a day when RBG hit 102 and 850's at SLE were 24.2C. If anyone has doubts about the effect of smoke on high temperatures (going back to some conversations earlier this month), this is a good example. 

 

Definitely holding things back a bit for us today as well, it appears.

[Deweydog]

Interesting pattern evolution the models are starting to settle on. A practically seamless transition from a mid summer-type heat pattern to a more amplified fall-like setup over the course of 5-6 days.