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April 2017 Observations and Model Discussion for the Pacific Northwest


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This is most likely not going to be a repeat of 2016... but very curious how Spring is going to start in the PNW. No matter what our overall year looks like; April can go from both ends of the spectrum (April 2015 vs. 2016 was really a world of difference in some areas, including mine).

 

Some hints of cool downs or continued wet weather on models but as long as my winter is wrapping up I don't think I mind much of what's coming!

Ashland, KY Weather

'23-'24 Winter

Snowfall - 5.50"
First freeze: 11/1 (32)
Minimum: 2 on 1/17

Measurable snows: 4
Max 1 day snow: 3" (1/19)

Thunders: 11
1/27, 1/28, 2/10, 2/22, 2/27, 2/28, 3/5, 3/6, 3/14, 3/15
3/26, 

-------------------------------------------------------
[Klamath Falls, OR 2010 to 2021]
https://imgur.com/SuGTijl

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First reply will be by a person not from the Pacific Northwest.

 

Last year was strange. Pacific Northwest had April heat waves while Southern California stayed cool.

 

Half of the month of April 2016 convection occurred in southern Oregon, and I average 0.7 t'storm days in April. lol It was a special case....

Ashland, KY Weather

'23-'24 Winter

Snowfall - 5.50"
First freeze: 11/1 (32)
Minimum: 2 on 1/17

Measurable snows: 4
Max 1 day snow: 3" (1/19)

Thunders: 11
1/27, 1/28, 2/10, 2/22, 2/27, 2/28, 3/5, 3/6, 3/14, 3/15
3/26, 

-------------------------------------------------------
[Klamath Falls, OR 2010 to 2021]
https://imgur.com/SuGTijl

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Kind of a crummy first day of April here.

Snowfall                                  Precip

2022-23: 95.0"                      2022-23: 17.39"

2021-22: 52.6"                    2021-22: 91.46" 

2020-21: 12.0"                    2020-21: 71.59"

2019-20: 23.5"                   2019-20: 58.54"

2018-19: 63.5"                   2018-19: 66.33"

2017-18: 30.3"                   2017-18: 59.83"

2016-17: 49.2"                   2016-17: 97.58"

2015-16: 11.75"                 2015-16: 68.67"

2014-15: 3.5"
2013-14: 11.75"                  2013-14: 62.30
2012-13: 16.75"                 2012-13: 78.45  

2011-12: 98.5"                   2011-12: 92.67"

It's always sunny at Winters Hill! 
Fighting the good fight against weather evil.

 

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A pretty much dry day here. Mostly cloudy with only 0.03" of rain early this morning.

Mercer Island, 350 ft

2021-2022: 11.6", 02/21

2020-2021: 15.6"

2019-2020: ~10"

2018-2019 winter snowfall total: 29.5"

2017-2018: 9.0", 2016-2017: 14.0"

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High of 66 today, was clear earlier then slowly became partly cloudy.

 

I'd say decent start for April. The avg high is 53 this time of year.

Ashland, KY Weather

'23-'24 Winter

Snowfall - 5.50"
First freeze: 11/1 (32)
Minimum: 2 on 1/17

Measurable snows: 4
Max 1 day snow: 3" (1/19)

Thunders: 11
1/27, 1/28, 2/10, 2/22, 2/27, 2/28, 3/5, 3/6, 3/14, 3/15
3/26, 

-------------------------------------------------------
[Klamath Falls, OR 2010 to 2021]
https://imgur.com/SuGTijl

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Here's an interesting tidbit: With an average temperature of 34F, March was the coldest month of the winter in Boston, easily beating out December, January, and February. That has never happened in recorded history.

 

Also, the coldest recorded NH temperature occurred just a few weeks ago, well after climo, alongside the coldest 850mb temperature ever recorded in March anywhere on the planet.

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#first60watch

 

.CLIMATE...The last time Missoula, Montana had a high temperature

of 60 degrees or more was on October 9th, 2016, or 174 days ago
as of April 1st. This ties the longest period of time between last
and first 60 degree days in the 124 year climate history of
Missoula. We are likely to break this record today since it is
very unlikely Missoula will reach 60 degrees today. This also
moves us into a tie for 12th latest first 60 degree day in climate
history for Missoula, the latest of which occurred on April 19th,
1945. We should see our first 60 degree day this week, likely on
either Wednesday or Thursday if the forecast holds. This would
firmly place 2017 within the top 10 latest first 60 degree days on
record. 

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Here's an interesting tidbit: With an average temperature of 34F, March was the coldest month of the winter in Boston, easily beating out December, January, and February. That has never happened in recorded history.

 

Also, the coldest recorded NH temperature occurred just a few weeks ago, well after climo, alongside the coldest 850mb temperature ever recorded in March anywhere on the planet.

Catastrophic global cooling continues.

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Both look pretty nice, not much contrast. I guess one is a perfect bluebird summer day, and the other is a regular spring day captured during a sun break?

 

The trees were much more leafed out last year... and the grass was already close to summer form.   

 

It has been partly to mostly sunny at times for the last couple hours here.

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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12z runs say we remain coolish and unsettled after a warm and dry break on Tuesday/Wednesday.

 

ECMWF shows a solid band of rain passing through on Wednesday afternoon.   

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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Scott Sistek's blog on the ridiculous rain of late... Seattle breaks more rainfall records.   Becoming the norm this decade.

 

http://komonews.com/weather/scotts-weather-blog/guess-what-seattles-breaking-another-rainfall-record

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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ECMWF shows a solid band of rain passing through on Wednesday afternoon.

Maybe for up there. Looks like a 65-ish day with maybe some rain later on down here.

 

Although we will be in the Bellingham area Tuesday-Friday this week. Definitely looking like a wetter pattern up there.

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Maybe for up there. Looks like a 65-ish day with maybe some rain later on down here.

 

Although we will be in the Bellingham area Tuesday-Friday this week. Definitely looking like a wetter pattern up there.

 

 

ECMWF shows mostly mid to upper 50s down there on Wednesday... maybe a few spots on the east side touching 60.   Clouds thicken early and rain is moving in by mid afternoon during the peak heating time.

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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ECMWF shows mostly mid to upper 50s down there on Wednesday... maybe a few spots on the east side touching 60. Clouds thicken early and rain is moving in by mid afternoon during the peak heating time.

You would have a better idea on Euro details with the maps you have access to. It must be way out of phase with the GFS then, which has been toying with the idea of a push toward 70 on Wednesday for PDX.

 

Granted the GFS has been toning that down in recent runs, though. Probably playing catch up.

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Scott Sistek's blog on the ridiculous rain of late... Seattle breaks more rainfall records.   Becoming the norm this decade.

 

http://komonews.com/weather/scotts-weather-blog/guess-what-seattles-breaking-another-rainfall-record

Reading through this and related linked articles, I was somewhat surprised to see forecasts calling for another hot summer in the west.

 

http://komonews.com/weather/scotts-weather-blog/enjoying-the-wet-february-some-signs-pointing-to-a-wetter-spring-too

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Reading through this and related linked articles, I was somewhat surprised to see forecasts calling for another hot summer in the west.

 

http://komonews.com/weather/scotts-weather-blog/enjoying-the-wet-february-some-signs-pointing-to-a-wetter-spring-too

The pattern we have been seeing with south to southwesterly flow and troughing staying just offshore has me thinking it's possible. There will come a point in a month or so that this 500mb setup becomes a fairly warm one for us, if it persists.

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Reading through this and related linked articles, I was somewhat surprised to see forecasts calling for another hot summer in the west.

 

http://komonews.com/weather/scotts-weather-blog/enjoying-the-wet-february-some-signs-pointing-to-a-wetter-spring-too

I am not feeling it... cold springs don't normally turn into hot summers. I will believe when I see it.

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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I am not feeling it... cold springs don't normally turn into hot summers. I will believe when I see it.

This hasn't been a classic cold spring IMO. Most of the west was above average in March, including 75% of Oregon. Cool anoms were confined to northwestern Oregon and Washington.

 

Right now April isn't looking shockingly cool either. Probably a little below average the first week thanks mostly to cooler days, in what looks to be a continued SW flow driven wetter than average pattern. Places to the south and east of here in the Rockies, SW and intermountain west will continue to torch ahead of stubborn offshore troughing.

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Catastrophic global cooling continues.

Lol, well the system is preparing for it. Note the growing radiative deficit at the poles, surplus in the tropics, and the equatorward contraction of the z-cell budget/convective integral since 2012.

 

In laymans terms, the pattern to watch for in summer is a Baffin Bay/Hudson Bay vortex, +NAO, and cooling NATL. This is a circulation regime that reduces the transport of heat above 60N, cools the polar domain, and most importantly tightens the meridional thermal gradient, which is the key for the required

circulatory re-alignment.

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Way too soon to say this will be a cold spring. 4/2.

 

And as Jesse pointed out, March wasn't really cold, more just wet.

I think a wet summer is favored. Whether it's cool/wet, or just plain wet, will depend on the longitude of the NPAC trough, which depends on the longitude of the Pacific convection and polar mode. Unless the IPWP rapidly collapses and focuses convection on the dateline, a persistently ridgy western summer will be difficult to obtain, IMO.

 

The polar mode/NAM state (which is crucial in determining the antecedent NE-Pacific streamflow) hinges on the IO/ATL convection and particularly the strength of the IO/Asian monsoon, as well as the +QBO influence on the z-cells and subtropics, which sort of ties into the IO as well.

 

If we fall into a -NAM summer regime, that increases the chances of a cooler western summer. If we fall into a +NAM summer regime, that increases the chances of a warmer western summer, but will cool the Arctic (and the entire NH above 30N), relative to the tropics, ahead of next winter, which is a recipe for an exciting long-period wave train.

 

FWIW, we haven't seen a +NAM/+NAO summer since 2013.

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The final stratospheric warming occurs this week, which will flip the polar upper level circulation into its summer state until next fall. This is a crucial period for setting up the summer circulation, as the entire system state reorganizes during this time. Monitor the tropics and mid/high latitude wave train closely over the next 4 weeks for clues to the nature of the warm season exchange between the tropics and mid/high latitudes.

 

http://www.atmos.albany.edu/student/hattard/realtime/u_65N_10hpa.png

 

http://www.atmos.albany.edu/student/hattard/realtime/u_65N_10hpa_gefs.png

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Last spring, the final warming occurred very early, during the first few weeks in March. The next four weeks featured a profound shift in the tropical convection and global circulations away from their midwinter state, which allowed for myself and others to predict a gradual move towards a cooler/-PNA regime through boreal summer and autumn.

 

Will the system offer similar clues this year? We'll have to wait and see, as sometimes the signals following the final warning are subtle and require some digging to unmask.

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I think a wet summer is favored. Whether it's cool/wet, or just plain wet, will depend on the longitude of the NPAC trough, which depends on the longitude of the Pacific convection and polar mode. Unless the IPWP rapidly collapses and focuses convection on the dateline, a persistently ridgy western summer will be difficult to obtain, IMO.

 

The polar mode/NAM state (which is crucial in determining the antecedent NE-Pacific streamflow) hinges on the IO/ATL convection and particularly the strength of the IO/Asian monsoon, as well as the +QBO influence on the z-cells and subtropics, which sort of ties into the IO as well.

 

If we fall into a -NAM summer regime, that increases the chances of a cooler western summer. If we fall into a +NAM summer regime, that increases the chances of a warmer western summer, but will cool the Arctic (and the entire NH above 30N), relative to the tropics, ahead of next winter, which is a recipe for an exciting long-period wave train.

 

FWIW, we haven't seen a +NAM/+NAO summer since 2013.

 

There's really no such thing as a wet summer around here, outside of one or two outliers. A couple of well placed convective showers can easily be the difference between a "dry" and "wet" summer at a given station. June and September can get decent precip totals but that's due more to late starting summers and early starting falls - the wettest combined July + August on record at PDX for example still had less than 5" of total precip.

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There's really no such thing as a wet summer around here, outside of one or two outliers. A couple of well placed convective showers can easily be the difference between a "dry" and "wet" summer at a given station. June and September can get decent precip totals but that's due more to late starting summers and early starting falls - the wettest combined July + August on record at PDX for example still had less than 5" of total precip.

Sorry, should have clarified. I'm referring to the larger scale moisture advection regime over the entirety of northwest North America, as determined by the upstream circulation over the Pacific.

 

I expect a largely zonal/GOA trough pattern to open the warm season, which would increase the full column moisture transport into northwest North America, and deliver more precipitation to the region as a whole. Whatever your local microclimates do is beyond my pay grade.

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He's right Phill. Down here in Oregon once you go south of Portland the summers are really dry so a *wet* summer may mean a few decent showers unless your talking 1983 kinda wet.

See my clarification above. I'm referring to the macro-scale pattern tendencies that will be in play across the entire northwest North American continental domain, not the rainfall total in your backyard.

 

Generally speaking, a stronger Pacific jet stream/GOA trough increases moisture advection and precipitation across most of northwest North America, regardless of the time of year.

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