April 2017 Observations and Model Discussion for the Pacific Northwest

[Phil]

Enjoy it because if Phil's hunch is correct this might be one of only a handful of 80s this year. In 1954 we only saw 10 days of 80+, 27 in 1955 and 1964, 28 in 1948 and 30 in 1953. The 1950s were rough in Portland if you liked warm summers.

 

More recently in 2010 we only managed 37 days. The POR average is 52 days of 80+ a year while the 1981-2010 normal is 56 days.

 

The high was 88 days in 2015...amazing summer that year. The 67 days in 2013, 77 in 2014, 88 in 2015 and 71 in 2016 are unrivaled in terms of consecutive summers with >10% more 80s than normal.

I think there's a decent chance August and September run warmer unless the IPWP/IO fail to leave this pseudo Niña state.

 

This is a challenging year. Weak/unstable ENSO, QBO cycling, and a weakening sun under an IO/Indo regime that's only been seen during the early 80s and early 90s, following those powerful solar maximums.

[Front Ranger]

Was it really in jeopardy, though? Or, was the clown range GFS just wrong?

Not sure what you mean. It's been cool.

 

[Phil]

Also, last summer was an easier forecast given ENSO, though even then, mother nature threw some huge curveballs, most notably the unprecedented QBO hiccup, which was arguably the main reason the Niña failed to intensify. Easterlies resurged below 40mb under the new downwelling westerly wave, which destructively interfered thermo-kinetically with the Walker Cell.

 

This year, the potential for error is even higher, but at least the QBO appears to have sobered-up finally.

[Phil]

Not sure what you mean. It's been cool.

 

7dTDeptWRCC-NW.png

What? I said the warm-up would begin in late April, and last through early May (at least).

 

I never give exact start/end dates, because it's almost impossible to be that precise from several weeks out. You're always going to be somewhat off with timing when it comes to intraseasonal forcing over the background state, especially during seasonal transitions.

[SilverFallsAndrew]

Eugene hit 71 yesterday

[Front Ranger]

What? I said the warm-up would begin in late April, and last through early May (at least).

 

I never give exact start/end dates, because it's almost impossible to be that precise from several weeks out. You're always going to be somewhat off with timing when it comes to intraseasonal forcing over the background state, especially during seasonal transitions.

I specifically said May would be MUCH nicer than April a few weeks ago. Even though it's a little early, I'm gonna go ahead and congratulate myself on a great call.

[Phil]

I specifically said May would be MUCH nicer than April a couple weeks ago. Even though it's a little early, I'm gonna go ahead and congratulate myself on a great call.

That's called seasonal climatology. When April is anomalously cool/wet, May is almost always "nicer".

[Front Ranger]

That's called seasonal climatology. When April is anomalously cool/wet, May is almost always "nicer".

 

To a degree, you are right. And I did factor that in.

 

There have definitely been some wet April/May combos in the PNW, though. 

 

Some notable ones: 

1948 (led to a cool, wet summer)

1960 (average summer)

1969 (coolish summer)

1984 (cool summer)

1988 (average summer)

1993 (cool/wet summer)

2005 (average summer)

2009 (warm summer)

2010 (cool summer)

2011 (cool summer)

2014 (warm summer)

 

Overall, a lot of cool summers, only a couple warm ones.

 

Compared to years where May turned notably drier/warmer:

1958 (warm, dry summer)

1959 (average summer)

1963 (cool summer)

1965 (average summer)

1970 (warm, dry summer)

1972 (warm summer)

1978 (warm summer)

1980 (cool summer)

1991 (average summer)

1992 (warm summer)

1997 (average summer)

2002 (warm summer)

2013 (warm summer)

 

Way higher percentage of warm summers.

[jcmcgaffey]

Tim is missing out on another lovely day in Seattle.

 

Screenshot_1.png

You must wait all day until an opening in the clouds pop up to post that. It's been mostly cloudy and rainy most of the day today so far around the space needle. I can attest to that.

[TT-SEA]

You must wait all day until an opening in the clouds pop up to post that. It's been mostly cloudy and rainy most of the day today so far around the space needle. I can attest to that.

 

He does.   

[SilverFallsAndrew]

Beautiful evening. Weekend saved!

[Trainwreck]

I like to go on vacation and post about the weather at home as much as possible.

[Deweydog]

Eugene hit 71 yesterday

Mmmmmmm...

 

Sweaty hippies.

[Phil]

To a degree, you are right. And I did factor that in.

 

There have definitely been some wet April/May combos in the PNW, though.

 

Some notable ones:

1948 (led to a cool, wet summer)

1960 (average summer)

1969 (coolish summer)

1984 (cool summer)

1988 (average summer)

1993 (cool/wet summer)

2005 (average summer)

2009 (warm summer)

2010 (cool summer)

2011 (cool summer)

2014 (warm summer)

 

Overall, a lot of cool summers, only a couple warm ones.

 

Compared to years where May turned notably drier/warmer:

1958 (warm, dry summer)

1959 (average summer)

1963 (cool summer)

1965 (average summer)

1970 (warm, dry summer)

1972 (warm summer)

1978 (warm summer)

1980 (cool summer)

1991 (average summer)

1992 (warm summer)

1997 (average summer)

2002 (warm summer)

2013 (warm summer)

 

Way higher percentage of warm summers.

I certainly hope you're not using these rainfall statistics to make a summer forecast. Otherwise you're going to run into all kinds of problems.

[Front Ranger]

You must wait all day until an opening in the clouds pop up to post that. It's been mostly cloudy and rainy most of the day today so far around the space needle. I can attest to that.

 

 I don't monitor it all day. Just happened to check then and that's how it looked.

 

BFI reported zero rain today until the past hour.

[Front Ranger]

I certainly hope you're not using these rainfall statistics to make a summer forecast. Otherwise you're going to run into all kinds of problems.

 

Nah, just sharing info. Drier Mays are statistically more likely to lead to warmer summers, especially following wet Aprils.

[SilverFallsAndrew]

I've used rainfall to make predictions for upcoming months in a general sense and it often works out.

[Phil]

Nah, just sharing info. Drier Mays are statistically more likely to lead to warmer summers, especially following wet Aprils.

Sometimes, your data will provide subtle hints to the answer(s) you're looking for. So, when I looked through your seperate lists of years, I found a few signals.

 

Starting with your first list (1948, 1960, 1969, 1984, 1988, 1993, 2005, 2010, 2011, 2014). While these years are all over the place in terms of ENSO/tropics and QBO, I ignored that fact and aggregated them all for SSTAs on a relatively homogenous baseline, and came up with this look:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/86580808-00AA-4A33-A758-5BED69F3BC7E_zps2ae4arlx.png

 

While the wild differences in the tropics cancel out, the NPAC SSTA signature is a decent match to 2017.

 

Then, I did the same for your second list (1958, 1959, 1963, 1965, 1970, 1972, 1978, 1980, 1991, 1992, 1997, 2002, 2013), and obtained this result..

 

Look carefully at the Indian Ocean:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/EB04DF1D-08FE-476D-8321-7F128D3FC7FC_zpsc9aofgcf.png

 

Now, look carefully at the Indian Ocean today:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/4EBE28F8-7AAF-42F1-A3A0-BBAA7EEF30FD_zpseihlknyk.png

 

What you're seeing is a opposing signal in the subtropical Indian Ocean dipole, and an inverted Indo-China/WPAC SSTA gradient, which would naturally pull the convection towards the dateline and shift the Aleutian cyclone southwestward, leading to ridging across NW North America. That's the opposite of this year's tropical forcing state.

[Phil]

Now, having said all that, much of the variability in the lists of years you provided can be explained by ENSO. There are some big time +ENSO years in your second list, several of them being super-niños.

 

So, strong/super niño regimes like 1958, 1965, 1972, 1992, 1997, and 2009 obviously are not analogous to 2017. And that's not even including the strong niña transitions you included.

[Phil]

One last note of caution..the upcoming warm stretch is occurring due to an upstream AAM removal/jet retraction, which is coupled to the ongoing MJO wave. So, it's an intraseasonal excursion that will cycle back and eventually re-couple and/or yield to the EHEM background state. This will probably occur sometime between May 15th and May 25th, though you can never be "precise" with this kind of stuff..

[SilverFallsAndrew]

Reflecting on the past cold season, we put up some great cold numbers without a major Arctic outbreak. Nice to see, it was a poor mans 92-93, even colder some places, but with less snow west of The cascades

[BLI snowman]

Reflecting on the past cold season, we put up some great cold numbers without a major Arctic outbreak. Nice to see, it was a poor mans 92-93, even colder some places, but with less snow west of The cascades

They were pretty close both here in the Portland area and then throughout Whatcom County and Lower Mainland B.C.

 

1992-93 was snowier here but had less impressive cold and snowcover numbers.

 

I would say a lot of western WA from Kelso north to Everett even did slightly better on snow this year than 1992-93.

[GHweatherChris]

They were pretty close both here in the Portland area and then throughout Whatcom County and Lower Mainland B.C.

 

1992-93 was snowier here but had less impressive cold and snowcover numbers.

 

I would say a lot of western WA from Kelso north to Everett even did slightly better on snow this year than 1992-93.

Overall this winter wasn't really good at all, accentuated by the continuation of crap.

 

It got kinda cold, a bit snowy but not everywhere... just a blah winter.

[Jesse]

Overall this winter wasn't really good at all, accentuated by the continuation of crap.

 

It got kinda cold, a bit snowy but not everywhere... just a blah winter.

You and Andrew are both such IMBY weenies.

[stuffradio]

You and Andrew are both such IMBY weenies.

I'll concede that this winter was pretty good IMBY in terms of snow.

[VancouverIslandSouth]

Any heat will be super short lived this week; we'll probably have some clouds trapped on Wednesday with that system passing to the north. Then Thursday's heat might actually be cut-off by some developing Thunderstorms, wouldn't that be something. Hard to image we don't see clouds and showers hanging in through at least next Saturday if not Sunday. I'm liking the prospects for the start of May.

[wx_statman]

Definitely.

 

May 1, 1998 was a good one.

 

I remember that one well. Lots of lightning in the afternoon/evening. 

[BLI snowman]

I remember that one well. Lots of lightning in the afternoon/evening. 

 

I mostly remember it because it ushered in an exceedingly wet/crappy May. Hit 90 on 4/30 and 84 the next day and then we didn't touch 70+ for about a month.

[SilverFallsAndrew]

You and Andrew are both such IMBY weenies.

The last week of February/ first week of March saved this winter imby

[SilverFallsAndrew]

Hit freezing this morning. Good way to start May.

[WeatherArchive]

Hit freezing this morning. Good way to start May.

Did it hurt?  

[ShawniganLake]

For southern Vancouver island April ended as a wet month. 143% of normal for Shawnigan Lake and 156% at Victoria. Temperatures just slightly on either side of normal, within ~0.5F.

[wx_statman]

I mostly remember it because it ushered in an exceedingly wet/crappy May. Hit 90 on 4/30 and 84 the next day and then we didn't touch 70+ for about a month.

 

No kidding. 5.55" of rain that month at PDX. 

 

Jul-Sep made up for it though.

[Jesse]

Looks like PDX ended up at -1.6 for April, which is respectable.

 

I'd have to re-check the numbers, but just going off the top of my head I think that would make it their coolest April since 2011! Not that there's been a lot of competition the last five years.

[Jesse]

How April ended up regionally:

 

[VancouverIslandSouth]

For southern Vancouver island April ended as a wet month. 143% of normal for Shawnigan Lake and 156% at Victoria. Temperatures just slightly on either side of normal, within ~0.5F.

 

At the airport. I'm pretty sure Victoria proper, particularly south of McKenzie was closer to average in terms of rain and above average in terms of temperature.

[TT-SEA]

For southern Vancouver island April ended as a wet month. 143% of normal for Shawnigan Lake and 156% at Victoria. Temperatures just slightly on either side of normal, within ~0.5F.

 

Sounds very wet... even in Victoria.    Except for some tiny area I guess.  

[Jesse]

The San Juans were pretty hott last month.

[crf450ish]

Dog Lake still frozen over on HWY 12 White Pass. Can't believe it. Absolutely incredible.

[epiceast]

Dog Lake still frozen over on HWY 12 White Pass. Can't believe it. Absolutely incredible.

Even though I've been by that lake many times, have never driven by it in May. But I do know that many alpine lakes at that elevation are definitely frozen between snoq & stevens passes.