August 2017 PNW Discussion Thread

[Deweydog]

76-77 at PDX tomorrow. Mild start, sunny afternoon.

74.

[Jesse]

74.

77.

[Jesse]

Had a band of light sprinkles earlier.

[wx_statman]

77.

 

I prefer the T.W.A.T. approach. Time Will Always Tell!

[Jesse]

I prefer the T.W.A.T. approach. Time Will Always Tell!

I think that may be the ace up Flatiron's sleeve. Like a magician, though, a world class forecaster never shares his secrets.

[Front Ranger]

I think that may be the ace up Flatiron's sleeve. Like a magician, though, a world class forecaster never shares his secrets.

 

That's correct.

 

And sometimes even world class forecasters have moments like this...

 

[Deweydog]

77.

The world watches and waits...

[TT-SEA]

The world watches and waits...

 

FWIW... GFS MOS shows 78 at PDX tomorrow.  Jesse might be wrong on the cool side.  

[Front Ranger]

FWIW... GFS MOS shows 78 at PDX tomorrow.  Jesse might be wrong on the cool side.  

 

   

[Kayla]

The world watches and waits...

 

Nah, everyone already did that on Monday.

[Deweydog]

9-3-17 is the new 9-2-88!

[wx_statman]

I think that may be the ace up Flatiron's sleeve. Like a magician, though, a world class forecaster never shares his secrets.

 

Forecasters or fishermen!

[Jesse]

Forecasters or fishermen!

Weatherbell subscription and dynamite. Cat's out of the bag!

[BLI snowman]

22c 850mb temp drop from hour 336 to hour 372. That would be fun.

[Jesse]

22c 850mb temp drop from hour 336 to hour 372. That would be fun.

 

To cold.

[BLI snowman]

To cold.

 

September will be coolish with a fair bit of rain. Then a bone dry and hot October (all time monthly record of 93 on the 7th).

[TT-SEA]

Rained overnight... still drizzling now.    Wish the SEA radar was functioning.   You would think they would use the 3 months of dry weather to get the regional radars in perfect working order so they don't keep failing during the 9 months of rain.  

[Front Ranger]

No rain at SEA. The ongoing stretch from 6/18 forward will go down as the longest streak under .05" (probably under .10") in SEA history.

[Jesse]

FWIW... GFS MOS shows 78 at PDX tomorrow. Jesse might be wrong on the cool side.

Already full sunshine up in the Salmon Creek area. 77 may indeed end up too cool.

[stuffradio]

Still mostly cloudy here. Cloudy day!

[TT-SEA]

Harvey is evil... that thing moves into SE Texas at a decent pace and then just completely stalls and spins over the same area for at least 5 days.  

The lack of a western trough to pull it up and out to the north seems to the problem.    It just runs into a western ridge wall.  

 

Total rain through Wednesday... and its still going at that time.

 

[Phil]

[Phil]

Record breaking SSTs noted on the northern/off-equator portion of the WPAC warm pool, right as the MJO arrives.

 

Given the cool tropical EPAC, the west is probably gonna roast, at least through the first half of September.

[ShawniganLake]

Record breaking SSTs noted on the northern/off-equator portion of the WPAC warm pool, right as the MJO arrives.

 

Given the cool tropical EPAC, the west is probably gonna roast, at least through the first half of September.

12z GFS agrees. September heatwave

[Front Ranger]

Record breaking SSTs noted on the northern/off-equator portion of the WPAC warm pool, right as the MJO arrives.

 

Given the cool tropical EPAC, the west is probably gonna roast, at least through the first half of September.

 

There was a pretty good signal for ridging in NW Canada from my main analogs going into summer. The result was western Canada being very warm, but much of the West ending up near normal. It will be interesting to see if that develops, as it would still line up with the tropical forcings.

 

 

June: Average to a little above average month for PNW. Composite analogs suggest ridging for the month is centered just offshore, meaning generally dry conditions for the PNW and cooler/wetter weather than normal inland in the West. Near normal to slightly warm in the East. Best chance of well above normal weather in the SE.

 

July: Primary ridging remains just offshore but at times right over West Coast. Warmer than normal conditions likely right along the coast, considerably cooler inland West and northern plains. Warmer than normal weather likely along the East Coast.

 

August: Warmer than normal throughout most of the West, much cooler for the eastern half of the nation. Sprawling, but fairly weak ridging over much of the West for the month, with troughing in the NE likely.

 

September: Decent signal for ridging up into NW Canada. Near normal temps for much of the West, with warmer temps in the SE, near normal in NE.

[Phil]

There was a pretty good signal for ridging in NW Canada from my main analogs going into summer. The result was western Canada being very warm, but much of the West ending up near normal. It will be interesting to see if that develops, as it would still line up with the tropical forcings.

Could be, but why did you change your forecast to cool/wet for September? I found that intriguing because I couldn't find any cool Septembers in years featuring late-blooming WPAC warmth, particularly during -QBOs.

[Kayla]

Landfalls at category 4 intensity, then just sits there and dumps like 4ft of rain.

 

What model shows 48" of rain?? I can't find any location or model showing more than 27" of rainfall over the next 10 days.

[Phil]

We started the warm season with raging EPAC warmth and an anemic IPWP (which favors cool/zonal flow across NW North America) so I based my cool June/July forecast (and warm August/September forecast) on the idea that it would take until the middle of the summer to transition away from the warm EPAC and build heat in the WPAC, while transitioning into a relatively modest -ENSO.

 

That transition ended up completing itself June, much faster than I'd thought, so we tightened the WC/flipped the ET wavetrain very quickly.

[Front Ranger]

Could be, but why did you change your forecast to cool/wet for September? I found that intriguing because I couldn't find any cool Septembers in years featuring late-blooming WPAC warmth, particularly during -QBOs.

 

I didn't. The only change I made was reducing the odds of a warm September in the West. My original forecast was for near normal in the West, because the only real signal I saw either way was for ridging in NW Canada. After the first half of summer pattern became clear, it began to look less likely that Sep would end up warm.

 

As I reiterated before, I've been going near normal to a little below for the PNW in Sep. +.5 to -1 for anomalies for most stations.

[Front Ranger]

Even if Sep ends up really warm in the PNW, it would still support my overall outlook for the summer. It's a seasonal forecast, so that's more important to me than any one month.   Now I just need the middle of the country to remain coolish and the SE to heat up in September.

 

[Phil]

I didn't. The only change I made was reducing the odds of a warm September in the West. My original forecast was for near normal in the West, because the only real signal I saw either way was for ridging in NW Canada. After the first half of summer pattern became clear, it began to look less likely that Sep would end up warm.

 

As I reiterated before, I've been going near normal to a little below for the PNW in Sep. +.5 to -1 for anomalies for most stations.

I'm not going to harp on this, since the month hasn't actually started yet, but you've reiterated your cool September forecast several times over the last 8 weeks or so. I have at least five screenshots confirming this.

 

Whatever happens, I hope you're academically honest about it.

[Kayla]

The GFS keeps the ridge going after this weekend and even strengthens it over the next 10 days. Would definitely seal PDX's all-time high for the month.

[Front Ranger]

I'm not going to harp on this, since the month hasn't actually started yet, but you've reiterated your cool September forecast several times over the last 8 weeks or so. I have at least five screenshots confirming this.

 

Whatever happens, I hope you're academically honest about it.

This is like the third time I've reiterated the .5 to -1 anomaly forecast, since you keep bringing it up. And you can read what I wrote about September in the predictions thread - it's all there.

[Phil]

Yeah, 1967 is interesting. It's -QBO/-ENSO, two years removed from a super niño, and featured a relatively weak sun. Hard to find a better match on paper.

 

It's also plastered everywhere on the CPC analog ensemble.

[Jesse]

Record breaking SSTs noted on the northern/off-equator portion of the WPAC warm pool, right as the MJO arrives.

 

Given the cool tropical EPAC, the west is probably gonna roast, at least through the first half of September.

Hopefully we can get a break after the first half of September. We will be looking at basically six weeks of mostly unbroken heat at that point.

[Front Ranger]

Hopefully we can get a break after the first half of September. We will be looking at basically six weeks of mostly unbroken heat at that point.

 

There was a break the middle of this month, albeit nothing impressive.

 

[TT-SEA]

Still cloudy and fall-like here this morning.  

[Jesse]

There was a break the middle of this month, albeit nothing impressive.

 

 

That's why I said mostly. Unnecessary flatironing here.

[TT-SEA]

Yeah, 1967 is interesting. It's -QBO/-ENSO, two years removed from a super niño, and featured a relatively weak sun. Hard to find a better match on paper.

 

It's also plastered everywhere on the CPC analog ensemble.

 

November 1967 had 17 dry days here in this area... that is outstanding for November.  

[Front Ranger]

Yeah, 1967 is interesting. It's -QBO/-ENSO, two years removed from a super niño, and featured a relatively weak sun. Hard to find a better match on paper.

 

It's also plastered everywhere on the CPC analog ensemble.

 

The dry stretch came to a screeching halt in 1967 with a big storm on 9/2. And October was VERY wet, with over 10" of rain for OLM.