April 2017 Observations and Model Discussion for the Pacific Northwest

[Front Ranger]

May of 1993 was quite warm and pleasant here... particularly after the first third of the month.

 

Numerous days in the 70s and 80s... peak of 87 on 2 different days.    

 

Given that its rained almost daily for all of February, March, and now April... it does not seem like a year that would turn nice for a week in late April and then be rainy and cold all of May and June.

 

1993 featured the driest February ever here and it was decent through a good part of March before a very wet April.

 

All of the years with extremely wet Feb-Apr periods improved dramatically in May and June.  Years like 1950, 1961, 1972, and 2014 which were among the wettest in history in late winter and early spring.  2017 is going to be the top dog in that list.  

 

I highly doubt this summer will turn out like 1993.

[Phil]

I left out 1972 because it's a decent early spring analog, but erupts with dateline convection in late Spring/early summer and goes super-niño from there. Also, I've mentioned several times that I expect a warm-up to start in late-April, lasting 2-3 weeks.

 

Now, let's looks at the boreal spring convective states in the years of 1993, 1991, 1983, and 1980. Very solid match. Looks like an even cooler IO this year, relatively speaking.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/B4C846AD-65FD-4763-900C-D4A89342E6A3_zpsg8lrkeru.png

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/C677601D-58DB-4537-854C-D5DCDA57A67E_zpso24yt2qt.png

[Phil]

You always exclude 1972 in these maps.

 

And I am looking forward to a nice stretch of 70s and 80s for most of May like 1993!

 

We cannot just always follow combinations of the worst analogs. Missing the best part of the cold and wet years and only matching the worst parts.

Do you have a method for checking your biases? I'm just curious because every year when I compile your analogs I get the same exact result. This the JJA mean for your aforementioned analogs of 1950, 1961, 1972, and 2014.

 

Looks like something I would wishcast.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/F7BE108B-F8F0-45AE-B012-3AC7F2F31946_zpskx7z2oxu.png

[TT-SEA]

Do you have a method for checking your biases? I'm just curious because every year when I compile your analogs I get the same exact result. This the JJA mean for your aforementioned analogs of 1950, 1961, 1972, and 2014.

 

Looks like something I would wishcast.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/F7BE108B-F8F0-45AE-B012-3AC7F2F31946_zpskx7z2oxu.png

Second year in a row we have been discussing 1983 and 1993.  

 

Last summer was way nicer than both years.

 

Last year we had a blooming Nina... this year its the opposite. Same analogs it seems.

 

The years I listed were extremely wet Feb-Apr periods like this year. That is all. Staying wet and cool seems unlikely.

[Front Ranger]

Another super dreary day in Seattle.

 

[SilverFallsAndrew]

Nice evening after a chilly 50/37 today. 0.24" of rain.

[TT-SEA]

Another super dreary day in Seattle.

 

Screenshot_1.png

 

It was a pretty nasty day from SEA southward and over the I-90 corridor.   Frequent downpours and hail.  

 

We are all aware of how the rain shadow works over Seattle in set ups like this one.  

[SilverFallsAndrew]

It was nice in Salem.

[Front Ranger]

It was a pretty nasty day from SEA southward and over the I-90 corridor.   Frequent downpours and hail.  

 

We are all aware of how the rain shadow works over Seattle in set ups like this one.  

 

A whopping trace of precip at SEA today.

[TT-SEA]

A whopping trace of precip at SEA today.

 

 

Yep... SEA was just north of the line of fire from Hoquiam to Snoqulamie Pass.  

 

OLM is good representation of the areas outside the rain shadow.

 

http://w1.weather.gov/data/obhistory/KOLM.html

 

In the 40s in the middle of the afternoon with rain.

 

It was downright nasty here at times this afternoon.   Worst day of the week by far.  If Jim was posting... he would gladly confirm the nastiness.

[Front Ranger]

Yep... SEA was just north of the line of fire from Hoquiam to Snoqulamie Pass.  

 

OLM is good representation of the areas outside the rain shadow.

 

http://w1.weather.gov/data/obhistory/KOLM.html

 

In the 40s in the middle of the afternoon with rain.

 

It was downright nasty here at times this afternoon.   Worst day of the week by far.  If Jim was posting... he would gladly confirm the nastiness.

 

Interesting you bring up OLM...a lot more sun there this month compared to March so far.

 

In March, OLM had 21 days with less than 30% possible sunshine. This month, they've only had 6 such days so far. 

[Phil]

Second year in a row we have been discussing 1983 and 1993.

 

Last summer was way nicer than both years.

 

Last year we had a blooming Nina... this year its the opposite. Same analogs it seems.

 

The years I listed were extremely wet Feb-Apr periods like this year. That is all. Staying wet and cool seems unlikely.

Well, there are some similarities to last year (particularly in the extratropics), but the progression of the low frequency wave train will be opposite. Last year started out warm/+PNA and trended progressively colder/-PNA (relative to average). This year will start out cool with the extended NPAC jet, and trend progressively warmer/drier late in the summer as the Niño builds westward towards the dateline.

 

I also don't expect the pattern to emulate 2016. Last summer featured a dominant GOA ridge, while this summer will feature a GOA trough. However, the entire climatological wavetrain will be shifted east of post-1998 Niño climo this year with the much colder IO and lackluster dateline convection to open the summer. So that trough will be lurking just offshore for awhile, at least until the dateline regime flips..probably in mid/late July or August.

[TT-SEA]

Well, there are some similarities to last year (particularly in the extratropics), but the progression of the low frequency wave train will be opposite. Last year started out warm/+PNA and trended progressively colder/-PNA. This year will start out cool with the extended NPAC jet, and trend progressively warmer/drier late in the summer as the Niño builds westward towards the dateline.

 

I also don't expect the pattern to emulate 2016. Last summer featured a dominant GOA ridge, while this summer will feature a GOA trough. However, the entire climatological wavetrain will be shifted east of post-1998 Niño climo this year with the much colder IO and lackluster dateline convection to open the summer. So that trough will be lurking just offshore for awhile, at least until the dateline regime flips..probably in mid/late July or August.

 

Good information... thanks for the explanation.

[TT-SEA]

Interesting you bring up OLM...a lot more sun there this month compared to March so far.

 

In March, OLM had 21 days with less than 30% possible sunshine. This month, they've only had 6 such days so far. 

 

I only brought up OLM regarding the weather today because I was watching the radar and whatever was over OLM was over my house about 90 minutes later and even more nasty.  

[TT-SEA]

Watching the lovely festivities from Pyongyang on CNN... going to be 77 degrees there today (tomorrow to us).

 

They have an interesting climate.  Cold and snowy all winter and then flips to really warm starting later in April or early May.  Very much like Minneapolis or Chicago.

[Front Ranger]

My top late spring/summer analogs at this point are 1960, 1982, 1984, and 1996.

[TT-SEA]

My top late spring/summer analogs at this point are 1960, 1982, 1984, and 1996.

 

Just looking at May... it rained on only 2 days in May of 1982 but rained almost every day of May in 1984.  

 

Which is it?   Those are polar opposites for this area.  

[TT-SEA]

My top late spring/summer analogs at this point are 1960, 1982, 1984, and 1996.

 

Wondering how you came up with this odd mix?

 

1960, 1984, and 1996 all stayed on the cool side of neutral for the rest of the year... while 1982 exploded into one of the strongest Ninos ever.

[dairyd]

Well, there are some similarities to last year (particularly in the extratropics), but the progression of the low frequency wave train will be opposite. Last year started out warm/+PNA and trended progressively colder/-PNA (relative to average). This year will start out cool with the extended NPAC jet, and trend progressively warmer/drier late in the summer as the Niño builds westward towards the dateline.

 

I also don't expect the pattern to emulate 2016. Last summer featured a dominant GOA ridge, while this summer will feature a GOA trough. However, the entire climatological wavetrain will be shifted east of post-1998 Niño climo this year with the much colder IO and lackluster dateline convection to open the summer. So that trough will be lurking just offshore for awhile, at least until the dateline regime flips..probably in mid/late July or August.

 

Seems to be a warm sst moving north to 30N around the dateline, interrupting the pacific jet flow for the next 2 weeks. Perhaps telling of a longer term pattern shift?

 

[Phil]

My top late spring/summer analogs at this point are 1960, 1982, 1984, and 1996.

Hmm, I don't have any of those in my list.

 

For ENSO/tropics (and QBO when applicable), I like 1934, 1943, 1980, 1983, 1991, 1993, and perhaps 2002.

[Phil]

Seems to be a warm sst moving north to 30N around the dateline, interrupting the pacific jet flow for the next 2 weeks. Perhaps telling of a longer term pattern shift?

 

sst.daily.anom4.14.17.gif

200z_07a.rnl.gif

200z_30a.rnl.gif

The coming jet retraction is due to the backcycle in the East Asian mountain torque exchange, removing angular momentum from the atmosphere upstream. It's temporary, and the jet will extend again, albeit in mid/late spring style.

 

Those SSTs are merely residual remnants of two bihemispheric oceanic rossby waves following the disintegration of the 2015/16 niño. They're not responsible for the jet retraction.

[Front Ranger]

Wondering how you came up with this odd mix?

 

1960, 1984, and 1996 all stayed on the cool side of neutral for the rest of the year... while 1982 exploded into one of the strongest Ninos ever.

I don't kiss and tell.

[Phil]

Just looking at May... it rained on only 2 days in May of 1982 but rained almost every day of May in 1984.

 

Which is it? Those are polar opposites for this area.

Yeah, some of these are perfect opposites globally. No offense to Flatiron, but this is actually kinda funny.

 

1996:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/0D3A2D0B-A480-4BCD-ACA7-5886E50416A8_zpsvcenyxle.png

 

1960:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/DBDC44AD-BE57-478E-AC6F-B6BF9B9C6081_zpseuats8ax.png

 

1982:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/D4AF9323-4B3E-42F7-86C7-675BCE9B1E3F_zpsuec2kecw.png

 

1984:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/0AC6B0F6-CB77-4413-930A-03CF7C5AFBB3_zpsumak4dgh.png

 

Both 1996 and 1984 are coherent east-based Niña with strong IPWP convection, while 1960 is pure WPAC and 1982 is Niño to high heaven.

[dairyd]

The coming jet retraction is due to the backcycle in the East Asian mountain torque exchange, removing angular momentum from the atmosphere upstream. It's temporary, and the jet will extend again, albeit in mid/late spring style.

 

Those SSTs are merely residual remnants of two bihemispheric oceanic rossby waves following the disintegration of the 2015/16 niño. They're not responsible for the jet retraction.

Except there seems to be surface highs forming in the area which ride the jet E then reinforcing an upstart western ridge.   It is a much different pattern than 2 weeks ago, particularly correlated with the SST. 

[TT-SEA]

Hmm, I don't have any of those in my list.

 

For ENSO/tropics (and QBO when applicable), I like 1934, 1943, 1980, 1983, 1991, 1993, and perhaps 2002.

 

For reference (including my reference later) here is a summary locally:

 

1934 - fairly hot in April and May and then a pleasant summer with no extreme heat and not much rain.

 

1943 - warm and pleasant April... crappy May... and then an absolutely perfect summer consistently in the upper 70s and low 80s and warm well into October.

 

1980 - warm and dry April... crappy May... then a summer like 1934.  

 

1983 - warm and dry April and May... crappy June and early July... pleasant for the rest of the summer with no extreme heat.

 

1991 - warm and dry April... crappy May and June... warm and dry through October.

 

1993 - wet April... warm May... crappy June and July... pleasant and dry through October with no extreme heat.

 

2002 - typical April and May... really nice from June - October but very little extreme heat.

 

 

Common theme locally in these years for the most part is a warm and dry April which does not seem to be happening this year.

[Phil]

Except there seems to be surface highs forming in the area which ride the jet E then reinforcing an upstart western ridge. It is a much different pattern than 2 weeks ago, particularly correlated with the SST.

Warm SSTs in the tropics/subtropics generally will reduce near surface pressures, if that's what you're referring to. A warmer surface boundary layer will promote convection, all else being equal.

 

Also, there's a semipermanent subtropical NPAC high that sits under the descending branch of the Hadley Cell year round, so I'm not quite sure what you're referring to here.

[Phil]

The idea that warm extratropical SSTAs force ridges is a farce.

 

Rather, it's the powerful, large scale interaction between the tropical convection and extratropical wavetrain(s) that forces the ridges, which then affects the higher latitude SSTAs. The strongest, most coherent systematic coupling between the atmosphere and oceans occurs in the tropics. There's very little of this, relatively speaking, outside the tropical domain.

[Phil]

1934 - fairly hot in April and May and then a pleasant summer with no extreme heat and not much rain.

 

1943 - warm and pleasant April... crappy May... and then an absolutely perfect summer consistently in the upper 70s and low 80s and warm well into October.

 

1980 - warm and dry April... crappy May... then a summer like 1934.

 

1983 - warm and dry April and May... crappy June and early July... pleasant for the rest of the summer with no extreme heat.

 

1991 - warm and dry April... crappy May and June... warm and dry through October.

 

1993 - wet April... warm May... crappy June and July... pleasant and dry through October with no extreme heat.

 

2002 - typical April and May... really nice from June - October but very little extreme heat.

 

 

Common theme locally in these years for the most part is a warm and dry April which does not seem to be happening this year.

 

Only 1934 and 1983 had dry Aprils, while 1943, 1980, 1991, 1993, and 2002 all featured wetter than average Aprils. The mean is also wetter than average.

 

Month-to-month variability is also highly dependent on intraseasonal behaviors. You can't get overly specific with analogs.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/DAEBC469-F48A-41F1-A7C4-025309DC6DA8_zpsbh3rff2k.png

[BLI snowman]

My top late spring/summer analogs at this point are 1960, 1982, 1984, and 1996.

I like 1954, 1967, 1976, 1981, 1998, 2011, and 2015 at this point.

[Phil]

I like 1954, 1967, 1976, 1981, 1998, 2011, and 2015 at this point.

[TT-SEA]

 

Only 1934 and 1983 had dry Aprils, while 1943, 1980, 1991, 1993, and 2002 all featured wetter than average Aprils. The mean is also wetter than average.

 

Month-to-month variability is also highly dependent on intraseasonal behaviors. You can't get overly specific with analogs.

 

 

 

Very true.

 

I was actually looking at the number of warm and dry days in April which would not show up well there.    Very subjective I suppose... but how I determine a nice warm season month.   April could have 5 very wet days and 25 dry days in the 60s and 70s but still could end up above normal for precipitation and most people would call it a beautiful month.  

 

That is a very different pattern than this month when it has rained some almost every day and most people consider it a crappy month even if its not a very wet month in terms of departure from average.

[TT-SEA]

I like 1954, 1967, 1976, 1981, 1998, 2011, and 2015 at this point.

 

1954 and 2015 were basically identical.  

[Phil]

Very true.

 

I was actually looking at the number of warm and dry days in April which would not show up well there. Very subjective I suppose... but how I determine a nice warm season month. April could have 5 very wet days and 25 dry days in the 60s and 70s but could end up above normal for precipitation. That is a very different pattern then this month when it has rained some almost every day.

Also, my 1934 analog is admittedly risky. It like it because it featured a raging +SIOD/cool IO, but the off-equator circulation was much different than today's. The climate system as a whole was behaving differently back then, with the transition from a neoglacial type circulation into a global warming circulation, composed of a rapidly expanding Hadley Circulation and strengthening Walker Circulation. This pumped truckloads of heat and mass poleward. This is the regime that we're just now exiting today, so it could pose problems for the older analogs in the early/mid 20th century.

 

I'm going all-in with the cool IO and reduced zonal Pacific SST gradient this year. At least into July. Afterwards, I'm not sure what happens yet.

[TT-SEA]

Also, my 1934 analog is admittedly risky. It like it because it featured a raging +SIOD/cool IO, but the off-equator circulation was much different than today's. The climate system as a whole was behaving differently back then.

 

I'm going all-in with the cool IO and reduced zonal Pacific SST gradient this year. At least into July. Afterwards, I'm not sure what happens yet.

 

I tried to explain my subjective reasoning a little better after you quoted me.  

 

I really can't determine how good or bad a warm season month was based just on temperature and precipitation anomalies.  August of 2015 was very wet here statisically... and yet was hot and sunny for most of the month.    September 2015 was colder than normal and was a gorgeous month with lots of sunny, dry days.

 

My criteria for rating a warm season month is almost entirely based on the number of mostly sunny and dry days.   

[Phil]

I tried to explain my subjective reasoning a little better after you quoted me.

 

I really can't determine how good or bad a warm season month was based just on temperature and precipitation anomalies. August of 2015 was very wet here statisically... and yet was hot and sunny for most of the month. September 2015 was colder than normal and was a gorgeous month with lots of sunny, dry days.

 

My criteria for rating a warm season month is almost entirely based on the number of mostly sunny and dry days.

Well, in that case my forecasts won't help you much. I'm forecasting solely on the large scale, from an upper level standpoint, so unless you can derive something from that, I can't help because I don't understand your surface climate very well.

[TT-SEA]

Well, in that case my forecasts won't help you much. I'm forecasting solely on the large scale, from an upper level standpoint, so unless you can derive something from that, I can't help because I don't understand your surface climate very well.

 

 

Yeah... I know.  I try to glean what I can from the patterns you predict.  

[stuffradio]

I picked up .54" of rain today, but the afternoon was very nice.

[Phil]

Greenland has added an impressive amount of ice so far this year, more than two standard deviations from climo. If we can avoid a big -NAO summer, there could be a notable surplus for the year.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/29562C48-A7C9-443E-B963-A3A604AFF85F_zpsemyb48dl.png

[Dave]

Some impressive mammatus clouds occurred in Springfield today.  I couldn't observe them from my location, unfortunately (not my pic).

 

[Front Ranger]

I like 1954, 1967, 1976, 1981, 1998, 2011, and 2015 at this point.

Agreed!!!