July 2019 Weather Discussion for the PNW

[Jesse]

Unfortunately the 06z scaled back on next week’s rainfall. Hope to see subsequent runs being it back.

[TT-SEA]

Sky is getting brighter now... hopefully that ULL can at least provide some decent mixing today.

[TT-SEA]

Unfortunately the 06z scaled back on next week’s rainfall. Hope to see subsequent runs being it back.

 

12Z run looks like the 06Z run so far... through Thursday.

[Anti Marine Layer]

1983 was a super strong El Nino, so I'm guessing the sea surface temperatures were probably more like Hawaii than Southern California and that accounted for the well above average lows and highs that year.

[Phil]

12z GFS keeps that Greenland block cranking.

 

As long as that thing is present, the 4CH should remain suppressed, given the structure of the EPAC ITCZ/HC, irrespective of run-to-run variability.

[TT-SEA]

PDX at one point last night was reporting smoke from all the fireworks.

 

 

Just noticed that SEA went to down to visibility of 4 miles with haze in the 10 p.m. - midnight period last night as well.    No doubt from fireworks.

[Phil]

In addition to the marine layer... there is a thick layer of haze and the smell of fireworks here probably due to very little mixing which is trapping it all in the valley. Pretty gross morning out there.

That happened here last night too (thanks to the 75/75, 100% humidity airmass). Particulate concentration surpassed 500ugm^3 and there was aerosol induced condensation smothering the landscape.

 

The fireworks at the mall were almost completely blocked out by the smog at one point.

 

[MossMan]

Anybody want a hot dog?

Is it too late?

[TigerWoodsLibido]

Cloudy and 61F in the s valley this morning.

[Front Ranger]

12z GFS keeps that Greenland block cranking.

 

As long as that thing is present, the 4CH should remain suppressed, given the structure of the EPAC ITCZ/HC, irrespective of run-to-run variability.

 

Models have been consistently moving forward with the timing of the 4CH emerging soon. EPS for day 6. 

 

 

Certainly a bit later than usual. Although it really didn't get cranking in several recent years until July.

[Jesse]

Models have been consistently moving forward with the timing of the 4CH emerging soon. EPS for day 6. 

 

ecmwf-ens_z500a_namer_7.png

 

Certainly a bit later than usual. Although it really didn't get cranking in several recent years until July.

 

It is suppressed to the south and east compared to recent years, though. I think that's what he meant. I don't think there has ever been a year where it's never formed.

[Phil]

Models have been consistently moving forward with the timing of the 4CH emerging soon. EPS for day 6.

 

ecmwf-ens_z500a_namer_7.png

 

Certainly a bit later than usual. Although it really didn't get cranking in several recent years until July.

Eh, looks more like a temporary response to the CCKW passage, right? The background state doesn’t look conducive to a strong 4CH at all, in my opinion. And even when it flares up with the shorter term cycles in forcing, it has been more suppressed.

 

Of course it will briefly/intermittently strengthen even in years when it’s generally weaker than average. But that’s a given for almost anything as it relates to weather.

[Phil]

It is suppressed to the south and east compared to recent years, though. I think that's what he meant. I don't think there has ever been a year where it's never formed.

Yeah, I never implied it wouldn’t exist or flare up episodically. It always does.

 

But this year, due to factors discussed earlier, it’s generally weaker, and/or suppressed equatorward, depending on the structure of the convection and AAM budget/transports.

[Phil]

This could change in August, as nonlinear forcing conduits open up via the acceleration of tropical activity across the WHEM, but it also might have the opposite effect depending on timing/freq of waves & the wavenumber at the time.

 

I don’t have the answer. August/September are always the most vulnerable to this behavior as the seasonal cycle itself is somewhat belated nowadays, but it doesn’t necessarily have to continue.

[Farmboy]

Unfortunately the 06z scaled back on next week’s rainfall. Hope to see subsequent runs being it back.

Because nothing screams mid July like a rainy week...

[Jesse]

This could change in August, as nonlinear forcing conduits open up via the acceleration of tropical activity across the WHEM, but it also might have the opposite effect depending on timing/freq of waves & the wavenumber at the time.

Blowtorch August? It’s been awhile.

[Jesse]

Some nice ensembles.

 

[Deweydog]

Haha...

 

https://www.kgw.com/mobile/article/news/nation-world/alaskas-largest-city-has-hit-90-degrees-for-the-first-time-ever/283-90fa53f2-89a8-48d7-ae2d-378f325365d0

 

The global warming freaks are gonna when they see this one!

[TT-SEA]

12Z ECMWF scaled back the precip for Wednesday even more than the 00Z run.   

 

It shows very little even in WA that day... and much warmer than the 00Z run as well.    Probably mid to upper 70s in the Seattle area and low 80s from Portland southward.   And then slightly warmer on Thursday.

[Phil]

Blowtorch August? It’s been awhile.

I’m not sure I’d go that far.

 

Again, for whatever it’s worth, the correlation between the early season northern annular mode and mid/late summer wavetrain suggests a *relatively* cool August (similar to July, perhaps) but the trends in WPAC warm pool/ITCZ seasonality over recent decades would suggest the opposite. The WPAC is hard to ignore given it’s the most prolific heat engine on the planet, through which many emergent system states are born.

 

So far, however, the annular mode correlation appears to be holding for the month of July, with big heat being tougher to come by. The WPAC has (and continues) to try and flip us back to that +NAO/+TNH pattern, but has been unsuccessful in doing so to this point.

[TacomaWaWx]

Overall still no real heat waves coming up for the first half of July. It’s been a nice first 5 weeks or so of the summer. Maybe even a bit of rain coming again next week though it’s hard to say how much or if it’ll pan out.

[Jesse]

I’m not sure I’d go that far.

 

Again, for whatever it’s worth, the correlation between the early season northern annular mode and mid/late summer wavetrain suggests a *relatively* cool August (similar to July, perhaps) but the trends in WPAC warm pool/ITCZ seasonality over recent decades would suggest the opposite. The WPAC is hard to ignore given it’s the most prolific heat engine on the planet, through which many emergent system states are born.

 

So far, however, the annular mode correlation appears to be holding for the month of July, with big heat being tougher to come by. The WPAC has (and continues) to try and flip us back to that +NAO/+TNH pattern, but has been unsuccessful in doing so to this point.

 

This whole post kind of just cancels itself out.

[Phil]

Because nothing screams mid July like a rainy week...

I get you’re being sarcastic, but this statement is actually 100% correct for much (if not most) of the country, where rainfall peaks during July.

[TT-SEA]

I get you’re being sarcastic, but this statement is actually 100% correct for much (if not most) of the country, where rainfall peaks during July.

 

 

He is specifically referring to PNW climo in July of course... because this is a PNW weather forum.

[Phil]

This whole post kind of just cancels itself out.

How so?

 

I’m saying I don’t know what the outcome will be in August, and there are reasons to favor both the “cool” outcomes and “warm” outcomes.

 

I tend to cling to the West-Pacific machine as the origin for emergent states, but the aforementioned wavetrain correlations have a nearly unbroken record in recent decades.

[Phil]

He is specifically referring to PNW climo in July of course... because this is a PNW weather forum.

I get that.

 

It’s just funny to me with the broad context.

[Jesse]

Pretty solid Euro run overall.

[Deweydog]

Is it too late?

Sorry. Summer’s over dude.

[Farmboy]

I get that.

 

It’s just funny to me with the broad context.

It was written in the context of a PNW July...

[Jesse]

It was written in the context of a PNW July...

Over two weeks of 90 degree weather in a month doesn’t fit within the context of a normal PNW July either, but that’s what happened last year.

[Front Ranger]

It is suppressed to the south and east compared to recent years, though. I think that's what he meant. I don't think there has ever been a year where it's never formed.

 

Of course, and I wasn't inferring that he said it would be non-existent. It just looks very normal to me at this point, albeit running a little late.

 

I also think the 4CH has absorbed an unfair amount of the blame for recent warm seasons in the PNW. A strong, early forming 4CH almost always leads to big monsoon seasons in the SW, and they've been hit and miss recently. In addition, if you look at the actual 500 mb anomalies for some of the warmest summer months the PNW has seen, it's clear they were due more to big/persistent west coast ridging that wasn't actually an extension of a strong 4CH.

 

 

 

[Front Ranger]

Eh, looks more like a temporary response to the CCKW passage, right? The background state doesn’t look conducive to a strong 4CH at all, in my opinion. And even when it flares up with the shorter term cycles in forcing, it has been more suppressed.

 

Of course it will briefly/intermittently strengthen even in years when it’s generally weaker than average. But that’s a given for almost anything as it relates to weather.

 

Maybe...we'll see how things develop over the next month. But I'm still not convinced the 4CH is as big a factor as some seem to think for summer heat in the PNW.

 

When above normal heights are displaced near the PNW, average or below normal heights tend to dominate the Great Basin/SW/southern Rockies.

[Anti Marine Layer]

Lots of overcast and rain lovers here. Some people just cannot tolerate the summer.

[Jesse]

Lots of overcast and rain lovers here. Some people just cannot tolerate the summer.

You keep posting in the wrong thread.

[Deweydog]

Maybe...we'll see how things develop over the next month. But I'm still not convinced the 4CH is as big a factor as some seem to think for summer heat in the PNW.

 

When above normal heights are displaced near the PNW, average or below normal heights tend to dominate the Great Basin/SW/southern Rockies.

Agreement from above the fray!

[TacomaWaWx]

Lots of overcast and rain lovers here. Some people just cannot tolerate the summer.

lol nothing like someone from a different region of the country trying to tell people they shouldn’t or should prefer certain weather pattern because they don’t like a certain weather pattern where they live.

[Jesse]

Agreement from above the fray!

 

A beefed up 4CH plays a role in very long episodes of heat around here, though. Especially when it merges with the EPAC ridge. Seems that has happened a lot in the recent hot summers we have seen.

[Anti Marine Layer]

You keep posting in the wrong thread.

So does Phil

[Jesse]

So does Phil

Yeah but he adds valuable information sometimes

[TT-SEA]

12Z EPS:

 

5-10 day mean...

 

 

 

10-15 day mean...