May 2019 Weather Discussion PNW

[TT-SEA]

I was checking back on model performance... because I remember being in doubt about this weekend a week ago.

 

Here was the actual 500mb pattern this morning:

 

 

 

Here is what the ECMWF showed on the 12Z run one week ago today for this morning... not bad.

 

 

 

Here is what the GFS showed for today on the 00Z run last Friday for this morning... not so good for the West Coast.

 

[Omegaraptor]

I did last year. And in both 2014 and 2015. And I think this one will end up on the warm side too, but for a different reason (more 1997-like..warm SW flow ahead of a growing GOA vortex type regime).

 

 

Isn't 2002 also a possible analog? It was similar to 1997 but with a little more in terms of heat wave action I think. Still mostly consistent 70s and 80s throughout the summer.

 

1997 was a bit on the warm side especially in August and September and a cool June and start to July. 2002 was extremely close to the 1981-2010 historical average (but it had a cooler than normal May unlike this year).

[Phil]

The 12z EPS really expedites the jet extension during the D11-15 range.

 

This might be rushed, but y’all are gonna be praying for some sunshine once the floodgates open later this month..some very anomalous stuff in the pipeline at some point, looking at the AAM cycle, under what is already a regime of narrow z-cells/polar blocking.

 

[Phil]

Firehose D13-14.

 

[Phil]

The severe weather during the second half of the month is gonna be off the charts, too. I’ll wager at least one EF4 somewhere before the month is over.

[Phil]

Isn't 2002 also a possible analog? It was similar to 1997 but with a little more in terms of heat wave action I think. Still mostly consistent 70s and 80s throughout the summer.

 

1997 was a bit on the warm side especially in August and September and a cool June and start to July. 2002 was extremely close to the 1981-2010 historical average (but it had a cooler than normal May unlike this year).

Yes, definitely another possible analog. Though as you mentioned the inteaseasonal cycle was out of sync compared to this year.

 

And May will certainly start warm this year, but unlike last year it will flip zonal, then cool before the month closes. Last year it took until the start of June for the pattern to transition, while this year it will probably happen ~ 10 days sooner.

[SilverFallsAndrew]

At least I got to bask in an inch of rain today.

[SilverFallsAndrew]

Definite improvement with the 18z ensembles.

[Phil]

1997 was a pretty cool summer for the US. Not really warm in the PNW, either.

 

cd97.122.160.235.122.21.11.13.prcp.png

It was warm at all of the airports west of the cascades, which is what people here care about.

 

And I didn’t say anything about the rest of the US.

[SilverFallsAndrew]

1997 certainly did not stick out as a warm summer. I think there was a major trough that July that brought decent snows above 5-6,000 in the Cascades.

[Omegaraptor]

The 12z EPS really expedites the jet extension during the D11-15 range.

This might be rushed, but y’all are gonna be praying for some sunshine once the floodgates open later this month..some very anomalous stuff in the pipeline at some point, looking at the AAM cycle, under what is already a regime of narrow z-cells/polar blocking.

May 2013?

 

I mean, the odds that this verifies aren’t too high given how far out it is, but it would be great to see one last big rain event before dry season truly kicks in.

[ShawniganLake]

If the GFS verified we would see a 27 day+ dry streak. Summers are sure a lot longer than they used to be.

[TT-SEA]

If the GFS verified we would see a 27 day+ dry streak. Summers are sure a lot longer than they used to be.

Streaky nature of this year is getting annoying now. How about a couple days with rain mixed in each week? The offset to this will probably be 20 days of rain in a row here and that really does suck in the warm season. One extreme or the other.

[Phil]

[Phil]

The EPS is high and dry through D10.

 

 

But by D15 the firehose is well underway. Plenty more in the pipeline as well, taken verbatim.

 

[TT-SEA]

The EPS is high and dry through D10.

 

 

But by D15 the firehose is well underway. Plenty more in the pipeline as well, taken verbatim.

 

 

I am not saying you are wrong about the upcoming pattern for the second half of May... I get the same sense that it will be really wet.

 

But that map above for day 15 is not really a "firehose" for us. The top map is the strange one... showing the PNW being the only place with no precipitation in May.

 

Also... are these maps available on WB?

[TT-SEA]

00Z EPS also shows cold air locked in for the Midwest.

 

Normal high in Minneapolis is 66 today and will be in the low 70s soon.    The EPS shows that today will be the warmest day in the next 15 days there with a high of 68.   It shows the next 2 weeks mostly in the 50s with a couple days in the 40s mixed in.     MSP is already at -8 for May after the first 3 days.  

[Phil]

I am not saying you are wrong about the upcoming pattern for the second half of May... I get the same sense that it will be really wet.

 

But that map above for day 15 is not really a "firehose" for us. The top map is the strange one... showing the PNW being the only place with no precipitation in May.

 

Also... are these maps available on WB?

Well there is ensemble spread so of course it’s not going to look like a “firehose” this far out given latitudinal distribution of the jet axis. And the thermal gradient/wave amplitude are weaker at this time of year so precipitation totals will be reduced vs winter under a similar pattern.

 

And yeah, they’re available. Go to EPS section and select N-Hemi-Mean then Surface-Precipitation. Let me know if you needs links.

[TT-SEA]

Well there is ensemble spread so of course it’s not going to look like a “firehose” this far out given latitudinal distribution of the jet axis. And the thermal gradient/wave amplitude are weaker at this time of year so precipitation totals will be reduced vs winter under a similar pattern.

 

And yeah, they’re available. Go to EPS section and select N-Hemi-Mean then Surface-Precipitation. Let me know if you needs links.

 

 

And sometimes the 500mb pattern can be misleading in terms of precip in the PNW.

 

The 06Z GFS clearly shows the jet extension as well in the 12-16 day period.    But even this is not a firehose pattern for the PNW.

 

 

[TT-SEA]

Here is total precip for the next 384 hours for the PNW... not much for the lowlands despite showing a big pattern change in the long run.

 

Still almost nothing for Seattle and Portland...

 

[TT-SEA]

Even so... I would bet the last 2 weeks of May and the first week or two of June will average wetter than normal across the region.  

[ShawniganLake]

And sometimes the 500mb pattern can be misleading in terms of precip in the PNW.

 

The 06Z GFS clearly shows the jet extension as well in the 12-16 day period. But even this is not a firehose pattern for the PNW.

 

 

I guess we’ll see what a firehose can deliver this time of year. I usually think of slow moving ULL as being more likely to deliver heavy rain this late in the season

[Phil]

Hopefully this means I’m on my game, haha. Severe weather call looking good right now (and this is probably just an appetizer for the big kahuna outbreak coming up during the last 10 days of the month).

 

Sort of OT, but flashing warning lights are going off for a big time severe weather outbreak somewhere in the US during the 5/5 - 5/15 period, based on the state of the subseasonal AAM cycle and seasonal MJO phase shift with the upcoming WHEM cycle being the final trigger.

 

Been several years since the configuration has lined up this way. Possibly not since 2013 or even 2011/2012?

[Phil]

Here is total precip for the next 384 hours for the PNW... not much for the lowlands despite showing a big pattern change in the long run.

 

Still almost nothing for Seattle and Portland...

 

Much less than the EPS there, which has the jet focused farther north initially (though it will drift north with time as AAM propagates poleward). Then it will retract with a more classic offshore high/western trough temporarily taking hold in early June.

 

Then the transition to western ridging/-EPO occurs again, probably sometime in mid or late June as another intraseasonal pulse crosses the WPAC. The subsequent GOA trough/jet extension in July will be less intense than the current one, with reduced cold troughing and more zonal flow, etc, as the pattern slowly trends warmer as the El Niño re-establishes and a low pass signal develops over the east-central Pacific. By August a typical east based niño pattern (GOA trough with mild SW flow) should be well established with warmer than average conditions over the PNW..but no big heat since the Hadley Cell is actually narrow for once..so the 4-Corners High is favored to be weak/equatorward.

[TacomaWaWx]

Even so... I would bet the last 2 weeks of May and the first week or two of June will average wetter than normal across the region.

if i were a betting I would say you will be right. Since 2005 here locally we haven’t had a may/June combine for less than 1.19”of rain. (2018 was the record low for precip combined). It’d be suprising if we didn’t atleast get that. Either way we are behind on rainfall and rain in May and June will help but we will still be a little behind for the year still unless there’s a deluge.

[Phil]

Note the consequence of a narrow Pacific Hadley Cell regime: Ridging over NE-Canada/Baffin Island, an equatorward NPAC High, and what should be a much weaker 4-Corners High this season. Haven’t seen a narrow Pacific Hadley Cell in FOREVER. I’m excited to see how it affects things, assuming it persists.

 

In fact, relative to climo, the SW/4-Corners/Southern Plains area might be the wettest part of the US this summer.

[Kayla]

Hot. Pretty remarkable how similar this May is playing out compared to last year.

 

http://i65.tinypic.com/2enqpfp.png

[Front Ranger]

It was warm at all of the airports west of the cascades, which is what people here care about.

 

And I didn’t say anything about the rest of the US.

 

Warm August/September, but pretty close to average overall. Would be quite a bit cooler than recent summers.

[Front Ranger]

Hopefully this means I’m on my game, haha. Severe weather call looking good right now (and this is probably just an appetizer for the big kahuna outbreak coming up during the last 10 days of the month).

 

 

 

Note the words "seasonably favorable". 

[Front Ranger]

if i were a betting I would say you will be right. Since 2005 here locally we haven’t had a may/June combine for less than 1.19”of rain. (2018 was the record low for precip combined). It’d be suprising if we didn’t atleast get that. Either way we are behind on rainfall and rain in May and June will help but we will still be a little behind for the year still unless there’s a deluge.

 

Yeah, it would take a record wet May/June combo to erase the deficit built up from Portland north. Highly doubt most places will see 5-10" over the next couple months.

 

[TT-SEA]

Yeah, it would take a record wet May/June combo to erase the deficit built up from Portland north. Highly doubt most places will see 5-10" over the next couple months.

 

YearPDeptWRCC-NW.png

SEA is only -2.35 for the year.

[ShawniganLake]

GFS ensemble still looks warm and dry until further notice.

[Phil]

Warm August/September, but pretty close to average overall. Would be quite a bit cooler than recent summers.

Still warmer than 1981-2010 climo overall.

 

Stop flatironing.

[Phil]

Note the words "seasonably favorable".

Yes. Seasonably unfavorable would be the other end of the spectrum at-range.

 

Lots of #flatironing today.

[Omegaraptor]

We're not looking at a 2011 or 1983 repeat. We're not looking at a scorcher like 2014/5/7/8 either. What we're looking at is a mild summer, slightly above normal temps overall, with no big heat waves. Hopefully no wildfire smoke, maybe 10-12 90ºF+ days in Portland if 1997/2002 is anything to go by.

 

If that's going to be the case, I'm looking forward to it.

 

January 1998 was also a good month for snow in Portland with 8.5"... 

[MossMan]

Nice day! My dogs agree!

[TT-SEA]

Total precip for next 10 days per the 12Z ECMWF.

 

It looks like it would be a wet pattern at the 500mb level at the end of the run... but it all goes into CA.

[Omegaraptor]

but it all goes into CA.

 

Story of the last six months for rain in Portland.

[Farmboy]

Hopefully Idaho stays dry. It's amazing how warm 60 feels at 5,000 ft. !

[TigerWoodsLibido]

Same temp inside as outside.  Windows open and screen door day.