May 2019 Weather Discussion PNW

[Omegaraptor]

Does anyone know why May and June have the best chance at storm/convective activity in Portland?

 

Could just be anecdotal, but those two months seem to have a higher chance at storms than any other time of year.

 

Also, does it have anything to do with the May/June precipitation spike in parts of Eastern OR/WA?

[Phil]

Solid rain event last night for the Portland area. 0.60” at PDX with a little more falling here. Great to see, just a shame it will be turning bone dry for the foreseeable future now.

What’s the monthly total now?

[Omegaraptor]

What’s the monthly total now?

 

0.91", including the 0.41" that fell after midnight today.

[Phil]

You sound so sure of yourself. It will be interesting to see how your 'wet June' narrative plays out...

When did I say wet June? I actually said I think there will be a few ULLs early, followed by a dry stretch in the middle, then another cool/wet pattern late.

 

However, I’ve had a slow bias by ~ 1 week with this pattern progression, so maybe the first 10 days of June are dry with the next pocket of wave activity arriving during the middle of the month?

[Jesse]

What’s the monthly total now?

Little over an inch here. Little under at PDX. Still about 60% of average with nothing on the horizon now.

[Deweydog]

Euro!!!

[Phil]

there has to be a front of sorts as there is now a batch of storms near Dc

Yeah I wasn’t expecting strobe lightning and crashing thunder at 1AM with weak forcing this early in the summer. In July or August it’d be more typical..MLCAPE was weak sauce.

 

Probably remnant outflow/diff heating boundaries from earlier convection colliding with weak forcing along the WF boundary.

[Jesse]

Euro!!!

I will be traveling to the continent where all the magic happens later today. Hope to get its autograph!

[Phil]

Little over an inch here. Little under at PDX. Still about 60% of average with nothing on the horizon now.

Perhaps you’ll squeeze another 0.25” out of this pattern before the month is out. Some of the higher resolution models have convective precipitation wandering out of the higher terrain during the first half of the week.

[Front Ranger]

Rain did not make this far north... dry with high clouds here this morning.

 

SEA is +5.6 for May with .36 of rain so far... and the chances for more meaningful precip this month dwindling.

 

Last May ended up +5.0 with .12 of rain.

 

Not much of a difference really.   Even though the large scale pattern has been quite different.

 

Warm and dry.

[TT-SEA]

Sun is shining here now. Might be some convection later.

 

Tomorrow looks cool and wet out here... might not get to 60.

[Phil]

Looks like there will be on and off against convection on the east side for the foreseeable future. Good news.

 

That’s actually not bad at all.

 

And despite the ridgy interlude starting next weekend, there is already promise for another cool, wet pattern next month as renewed IO forcing and the removal of AAM via Eurasia (during the monsoonal inception, of all times) is the ideal conduit to anticyclonic wave dispersion over the NPAC (-PNA) and a western trough response.

 

So, at least this time, it doesn’t look like a sustained warm/dry pattern (irrespective of the current modeling).

[Phil]

The period of concern is what happens after that. Historically, you would expect WPAC convection to blow up following the EHEM forcing given the low-freq Pacific Walker/Hadley mode, with sustained diabatic forcing on the wavetrain.

 

So after that -PNA episode next month (whenever that is) there will definitely be heatwave potential that will persist until forcing propagates into the WHEM again, and large scale subsidence propagates over the warm pool engine once again.

[Jesse]

The period of concern is what happens after that. Historically, you would expect WPAC convection to blow up following the EHEM forcing given the low-freq Pacific Walker/Hadley mode, with sustained diabatic forcing on the wavetrain.

 

So after that -PNA episode next month (whenever that is) there will definitely be heatwave potential that will persist until forcing propagates into the WHEM again, and large scale subsidence propagates over the warm pool engine once again.

Lol.

[Phil]

Lol.

FWIW, I’m talking 5-6+ weeks out. But also keep in mind I’m using history/climo as a guide to help extrapolate the tropical forcing component and monsoonal evolution, so if this year is unique in some unforeseen way (like 2017) my method could be wrong.

 

Timing up in the air..maybe early July? I don’t know yet since, again, it depends on the exact evolution into the warm season circulation over the Eurasia/Indo-Pacific domain.

[Phil]

And it’s not a background state..it would last 2 weeks or less. But it looks like a solid intraseasonal pulse across the (dreaded) WPAC based on historically-similar evolutions of convective forcing and extratropical RWB cycles.

 

There was a similar event back in August of 2016 that brought 2 weeks of heat, but once that WPAC exhaust was cut off, so was the ridging. And this one (if it even happens) would be earlier in the season w/ less lackadaisical streamflow.

[TT-SEA]

And it’s not a background state..it would last 2 weeks or less. But it looks like a solid intraseasonal pulse across the (dreaded) WPAC based on historically-similar evolutions of convective forcing and extratropical RWB cycles.

 

There was a similar event back in August of 2016 that brought 2 weeks of heat, but once that WPAC exhaust was cut off, so was the ridging. And this one (if it even happens) would be earlier in the season w/ less lackadaisical streamflow.

Stop qualifying it!

 

Let me get through this torrential rain period first.

 

It has been pretty crazy. We had some high clouds late yesterday and there might be some drizzle tomorrow. Then we get a very brief 8-day break of sunshine of warmth per the ECMWF. But it probably wont last more than a week after the end of run and then back to endless rain again some time after day 15.

[Front Ranger]

The period of concern is what happens after that. Historically, you would expect WPAC convection to blow up following the EHEM forcing given the low-freq Pacific Walker/Hadley mode, with sustained diabatic forcing on the wavetrain.

 

So after that -PNA episode next month (whenever that is) there will definitely be heatwave potential that will persist until forcing propagates into the WHEM again, and large scale subsidence propagates over the warm pool engine once again.

Previously you were saying late summer would be the only real heatwave potential...

[Phil]

Stop qualifying it!

 

Let me get through this torrential rain period first.

 

It has been pretty crazy. We had some high clouds late yesterday there might be some drizzle tomorrow. Then we get a very brief 8-day break of sunshine of warmth per the ECMWF. But it probably wont last more than a week after the end of run and then back to endless rain again some time after day 15.

I’ll consider this fair game, as long as you don’t complain about rain or dreary patterns this summer.

 

If you do, I’m gonna go ham on your arse.

[TT-SEA]

I’ll consider this fair game, as long as you don’t complain about rain or dreary patterns this summer.

 

If you do, I’m gonna go ham on your arse.

 

 

Yeah... that would be fair.   And I might if it goes too far the other way.   I would like a balance. 

 

This past week has been just about perfect.   Its been quite sunny and pleasant overall and this weekend has been beautiful... yet we have also had about 1.5 inches of rain here in that time.   

[Phil]

Previously you were saying late summer would be the only real heatwave potential...

I changed my mind..very minor details in the grand scheme of things since we’re looking at a 10 day period, but seasonal transitions are tough to nail in advance and I think this is something that could happen now.

 

In this case, I’m merely adjusting for the timing of intraseasonal variability as it becomes clearer..even minor timing shifts of MJO periodicity/etc can have very important short term implications for certain regions.

[Phil]

Taken in Eugene yesterday.

 

https://mobile.twitter.com/kmtr/status/1129955565000581120

[Farmboy]

When did I say wet June? I actually said I think there will be a few ULLs early, followed by a dry stretch in the middle, then another cool/wet pattern late.

However, I’ve had a slow bias by ~ 1 week with this pattern progression, so maybe the first 10 days of June are dry with the next pocket of wave activity arriving during the middle of the month?

You've really been making it sound like summery weather will be nearly non-existent, you even said it will be the complete opposite of last summer, which I can only assume must mean more rain...

[Jesse]

You've really been making it sound like summery weather will be nearly non-existent, you even said it will be the complete opposite of last summer, which I can only assume must mean more rain...

If this is anything less than one of the hottest summers on record I’m pretty much gonna cry the next four months.

[Requiem]

You've really been making it sound like summery weather will be nearly non-existent, you even said it will be the complete opposite of last summer, which I can only assume must mean more rain...

 

The more rain, the better!

[Phil]

You've really been making it sound like summery weather will be nearly non-existent, you even said it will be the complete opposite of last summer, which I can only assume must mean more rain...

This is a combination of subjectively-derived gobbledygook and flat out misinformation.

[Guest CulverJosh]

Pretty ridiculous that Bend has no radar coverage. Looks like it is pouring only Redmond north but it is indeed pouring here. Unacceptable.

[SilverFallsAndrew]

Some winter weather advisories in Southern Oregon. 

[Jesse]

Looks like some rain moving toward PDX, which is more pertinent to me than ever right now.

[Anti Marine Layer]

This is a combination of subjectively-derived gobbledygook and flat out misinformation.

 

Is this cold May being caused by sudden stratospheric warming again?

[Timmy Supercell]

Just had a hailstorm, but no thunder though.

 

A few pieces looked 1/2" inch sized!

[Phil]

The 00z GFS brought back the ULL. Hopefully it stays put this time.

[Phil]

Is this cold May being caused by sudden stratospheric warming again?

The vigorous MJO/CCKW which was enhanced by the dynamic final warning last month (which is similar to a SSW).

 

Had a dynamic final warming in 2016 as well.

[TT-SEA]

The 00z GFS brought back the ULL. Hopefully it stays put this time.

Models are all over the place.

 

EPS has been the only consistent one.

[Phil]

Models are all over the place.

Monsoonal inception ftw. That and AAM loss.

 

Going to be a solid 2 weeks of model struggles.

[TT-SEA]

Monsoonal inception ftw. That and AAM loss.

 

Going to be a solid 2 weeks of model struggles.

Big picture has been consistent... just lots of model challenges over the PNW for next weekend.

[Phil]

Big picture has been consistent... just lots of model challenges over the PNW for next weekend.

Well, the “big picture” involves more than just North America. There hasn’t been much consistency over Eurasia, and that will inevitably reflect here as well.

[SilverFallsAndrew]

Quite a bit of rain in Eastern Oregon again today. Great to see. 

[Phil]

One of the scariest looking cyclones you’ll ever see this late in the season on Tuesday over the Plains. Going to be a nasty, nasty, nasty severe weather outbreak.

[Phil]

Wtf