April 2020 Weather discussion for the PNW

[Frontal Snowsquall]

Looking at Michael Ventrice’s hurricane season forecast, it looks like he’s also seeing low frequency tropical convective forcing increasingly centered over the Indian Ocean with time (mentions the descending easterly shear favoring a reduction in off-equator convection, which is generally true as well). Also, dateline/WPAC subsidence would typically correspond to uplift in the IO without the +IOD focusing uplift in the W-IO (can be a high wavenumber regime with a weak low pass) so that makes sense.

 

This would, based on history (even very recent history) suggest offshore Aleutian/GOA Ridging (-PNA) would be favored to dominate the warm, along with drier than average conditions, especially over the SW US and inland. But PWAT anomalies would be lower than average with such a pattern.

 

Looks like he's calling for an above average hurricane season. 9 hurricanes with 4 of them major.

[Jesse]

I guess I did.

 

The departures from normal in terms of precipitation are certainly much larger down there when reanalyzing boundary state analogs, and I’m very concerned about CA and the SW US this summer. More so than I’ve been in awhile. But even in the PNW, precipitable water anomalies and overall precipitation w/ respect to climo seems to decline as summer wears on, especially inland, even with a “cool” signal clearly present. Certainly, there’s nothing close to the level of moisture that was showing up in the analogs last year at this time.

 

It’s less “dry” in June on the West Side for some reason, but the signal flips around in July except up in BC and at the immediate coast, then it’s all dry in August, but it’s still a significantly cooler signal vs the one in WPAC forcing/+PMM years. There aren’t many IO/EHEM dominated summers, I suppose, so maybe it’s not a familiar pattern to memory? I’ll post all of this when I’m finished.

 

July and August are already pretty dry on average just by themselves. It's our driest time of year. So a dry July and August doesn't necessarily mean a very huge departure out this way. We don't have a summertime precip max like you guys do back east. Usually all it takes is one or two rainfall episodes to get us up to average for those months out here.

 

If we are able to get some decent rain in the next two months we will be better set up for our normally dry summer. What really screwed us over during terrible fire years like 2015/17/18 was having our normally showery mid to late spring period completely skipped over before embarking on a scorching and bone dry summer. If you are correct about the cooler part for this summer, that will help too, since cooler weather generally decreases evaporation in fuels and soils.

[Deweydog]

Breezy!

[TigerWoodsLibido]

61F and beautiful out there. Grateful to have nice weather so as to do some yard work.

[Omegaraptor]

East winds starting at PDX. RH is dropping like a rock.

[Frontal Snowsquall]

East winds starting at PDX. RH is dropping like a rock.

Dew point down to 30.

[TigerWoodsLibido]

Up to 63F DP 43F but surface winds are still coming out of the north down the valley, around the Coburg Hills and into Springfield from the west.

[Front Ranger]

61F and beautiful out there. Grateful to have nice weather so as to do some yard work.

I'm actually getting a little frustrated with the cold/snow here, as I've been trying to get a garden and landscaping projects going.

[TigerWoodsLibido]

I'm actually getting a little frustrated with the cold/snow here, as I've been trying to get a garden and landscaping projects going.

 

I'll trade you our sun for a bit of rain and in return we get a top-tier Arctic blast and a nice regional snow event in 20-21.  Sadly, mother nature likely won't deliver a 2-25-19 (in Dec-Jan) anytime in the foreseeable future.

[Jesse]

I'll trade you our sun for a bit of rain and in return we get a top-tier Arctic blast and a nice regional snow event in 20-21.  Sadly, mother nature likely won't deliver a 2-25-19 (in Dec-Jan) anytime in the foreseeable future.

Yup. At least 7 and a half months away.

[Jesse]

Fairly windy here with a temp of 67 and DP down into the mid-20s. Interesting to have another shot of relatively cool continental air. Could be more cold lows tonight in places where the wind dies.

[Phil]

July and August are already pretty dry on average just by themselves. It's our driest time of year. So a dry July and August doesn't necessarily mean a very huge departure out this way. We don't have a summertime precip max like you guys do back east. Usually all it takes is one or two rainfall episodes to get us up to average for those months out here.

 

If we are able to get some decent rain in the next two months we will be better set up for our normally dry summer. What really screwed us over during terrible fire years like 2015/17/18 was having our normally showery mid to late spring period completely skipped over before embarking on a scorching and bone dry summer. If you are correct about the cooler part for this summer, that will help too, since cooler weather generally decreases evaporation in fuels and soils.

Good information, thanks.

[TigerWoodsLibido]

70F but the DP is now down into the mid-30s here. East winds now blowing down the McKenzie Valley. 

[Jesse]

70F but the DP is now down into the mid-30s here. East winds now blowing down the McKenzie Valley.

Cross Cascade gradients!!

[Frontal Snowsquall]

[TacomaWaWx]

Up to 66 degrees here at 2:30pm...we will see if we can hit 70. 66 is the warmest temp of 2020 so far.

[TT-SEA]

71 here.

[Timmy Supercell]

This April may be even drier than last year. March, same thing, and I came off of a 5th driest February. 

[TT-SEA]

Landscape is transforming to summer...

 

[Frontal Snowsquall]

Landscape is transforming to summer...

 

Summer paradise!

[Phil]

Landscape is transforming to summer...

 

Needs some snow.

[Jesse]

Needs some snow.

Winter paradise!

[Phil]

Warmth seems fairly consolidated in the tropics across the Pacific and Indian Oceans for once, without insane OHC/SST anomalies centered in the off-equator subtropics. With -QBO/downwelling easterly shear aiding this process, the resemblance to the mid/late 1940’s may continue (that was the back when that prolonged +PMM/+PDO phase was turning the corner).

 

[TacomaWaWx]

67/42 today.

[Blizzard777]

70/37 currently 64*
Used the blower today on the back patio and really whipped up a nice pollen storm! 

[TacomaWaWx]

Today is day 17 on our dry streak...glad that the models have gone to wetter solutions for the final 3rd of the month. Looking forward to getting some rainfall again.

[Jesse]

Today is day 17 on our dry streak...glad that the models have gone to wetter solutions for the final 3rd of the month. Looking forward to getting some rainfall again.

 

Me too. Hopefully we get a nice couple week stretch of wet weather at times.

[Frontal Snowsquall]

70/37 currently 64*

Used the blower today on the back patio and really whipped up a nice pollen storm!

70/39 out here today. Going to be a beautiful sunset!

[Jesse]

69/38 here today, with some strong east winds at times in the afternoon.

 

DP is 24 here. If the wind dies down tonight it will drop well into the 30s again by morning.

[Jesse]

Glad to see the 00z GFS trend a little juicier with the Wednesday system next week.

[TigerWoodsLibido]

We sure need the pattern change here in the south valley. 9” below normal rainfall since Jan 1.

[Jesse]

Massive ensemble improvements.

 

[TT-SEA]

Massive ensemble improvements.

 

 

The GEFS ensemble mean maps look warmer and drier than the operational run.   

 

Here is the 16-day precip anomaly...

 

[Phil]

Not sure if this is a statistical fluke or not, but out of the top nine strongest-PV winters, zero of the *subsequent* winters were 1st year niñas, and only *one* was a niña at all (this being 2011, which was basically a continuation of the 2010/11 niña regime). The rest were all either neutral or niño, but the majority were neutral. Fascinating stuff given we’re heading away from +ENSO pretty quickly right now.

 

This past winter was #1 or #2 depending on what metric you’re using for PV strength..way up there. So it’ll be interesting to see if this streak gets broken. I don’t see a physical reason for it, but there may be one.

 

Worth pointing out, I guess.

[TigerWoodsLibido]

Not sure if this is a statistical fluke or not, but out of the top nine strongest-PV winters, zero of the *subsequent* winters were 1st year niñas, and only *one* was a niña at all (this being 2011, which was basically a continuation of the 2010/11 niña regime). The rest were all either neutral or niño, but the majority were neutral. Fascinating stuff given we’re heading away from +ENSO pretty quickly right now.

 

This past winter was #1 or #2 depending on what metric you’re using for PV strength..way up there. So it’ll be interesting to see if this streak gets broken. I don’t see a physical reason for it, but there may be one.

 

Worth pointing out, I guess.

 

11-12 was dudsville down this way but had its moments up north.

[ShawniganLake]

71 here.

Topped out at 71 here too. First 70 degree day.

[TacomaWaWx]

Euro and gfs look pretty sparse with precipitation on Saturday...especially north of Olympia. Might have to wait until Wednesday to break the dry streak. At least the end is in sight.

[TacomaWaWx]

Only hit 42 this morning...haven’t been in the 30s since Monday.

[Frontal Snowsquall]

The GEFS ensemble mean maps look warmer and drier than the operational run.

 

Here is the 16-day precip anomaly...

 

Getting a little better but still dry overall here in the PNW.

[TT-SEA]

Euro and gfs look pretty sparse with precipitation on Saturday...especially north of Olympia. Might have to wait until Wednesday to break the dry streak. At least the end is in sight.

 

 

We will probably get some rain on Wednesday... but the models are now showing that system moving through more quickly and splitting with the main focus heading into Oregon.

 

Regardless of the timing of individual systems... the pattern definitely looks wetter overall starting in the middle of next week.