September 2019 Weather Discussion for the PNW

[TT-SEA]

Maybe Tim could look up the verification scores, I’m pretty sure weatherbell has them. Last I saw, the euro was still ahead on large scale medium range 500mb patterns.

I don't know which model is leading the way overall. But I know for sure that for the last 3 months... the model showing the least amount of ridging in the PNW is the one that will end up more right.

[VancouverIslandSouth]

Rainy and windy here this morning, this is a day straight out of November; I can hear the rain pelting against the windows.

[TacomaWaWx]

Rainy and breezy down south as well. 0.12” so far and 54 degrees.

[Kayla]

ECMWF seasonal forecast. Decent out here but not so great for you guys. Looks like best shot is Dec/Jan but focused up in the Puget Sound lowlands.

 

November

 

December

 

January

 

February

[ShawniganLake]

I don't know which model is leading the way overall. But I know for sure that for the last 3 months... the model showing the least amount of ridging in the PNW is the one that will end up more right.

Yea I read a few of the posts regarding this conclusion yesterday. Thought maybe we could add some actual data to the discussion

[Front Ranger]

I don't know which model is leading the way overall. But I know for sure that for the last 3 months... the model showing the least amount of ridging in the PNW is the one that will end up more right.

 

Right now they're pretty similar for days 6-10. Not extremely ridgy or troughy overall.

[TT-SEA]

Cliff Mass post on the record number of warm nights this summer and the blob that is responsible...

 

https://cliffmass.blogspot.com/2019/09/why-have-our-low-temperatures-been-so.html

[Phil]

The 0z Euro was less troughy. GFS was less ridgy. Hard to say which one is "leading the way" at this point.

Easy there. It’s Sep 15th, not Nov 15th.

[Phil]

ECMWF seasonal forecast. Decent out here but not so great for you guys. Looks like best shot is Dec/Jan but focused up in the Puget Sound lowlands.

 

November

 

December

 

January

 

February

I’ve never seen those maps verify at this range. They had the same prediction for the PNW this time last year.

[Kayla]

Easy there. It’s Sep 15th, not Nov 15th.

 

...It's Sept 17th.

[Kayla]

I’ve never seen those maps verify at this range. They had the same prediction for the PNW this time last year.

 

Did they? I would be curious to see last years if you have them.

 

Obviously not a great predictor, but they can still be good to see possible large scale seasonal patterns and where the mean trough positions might set up.

[Deweydog]

...It's Sept 17th.

Thank you.

[Requiem]

ECMWF seasonal forecast. Decent out here but not so great for you guys. Looks like best shot is Dec/Jan but focused up in the Puget Sound lowlands.

 

November

 

December

 

January

 

February

 

I certainly won't be happy if the region has the same snowfall disparity as last year in terms of Puget Sound getting snow. But these maps aren't too accurate this far out anyways, so...

[Frontal Snowsquall]

Similar to flash floods in the SW and cold in N-Texas.

 

Doesn’t happen often, but when it does, it can be extreme and people aren’t acclimated.

Yeah, I was thinking not many people probably have AC out there. I know those areas can get big heatwaves too.

[Frontal Snowsquall]

Cliff Mass post on the record number of warm nights this summer and the blob that is responsible...

 

https://cliffmass.blogspot.com/2019/09/why-have-our-low-temperatures-been-so.html

Interesting take by Cliff. He makes some good points though.

[Jesse]

Nice day.

[MossMan]

Had a slight break in the action as I drove to work.

[Anti Marine Layer]

Everything is on fire up here... raging infernos all around us. This front is saving us! Whew.

 

Guess it ended a few weeks ago. Usually it takes a few decent storms in Southern California to end their fire season. A storm with 0.25" rainfall totals will not do the job.

[Frontal Snowsquall]

ECMWF seasonal forecast. Decent out here but not so great for you guys. Looks like best shot is Dec/Jan but focused up in the Puget Sound lowlands.

 

November

 

December

 

January

 

February

The December and January maps have tons of potential. Always good to see a cold and snow covered Columbia River Basin. Based on the maps alone, it's probably thinking a backdoor Arctic Blast(s). I feel we might see an ice storm or two here this winter. Won't take much of a shift for everyone west of the Cascades to get high snow anomalies.

[Deweydog]

More strong but DRY Arctic fronts...

 

Ugh.

[Phil]

...It's Sept 17th.

Haha.

 

My brain is completely fried. Not sure I’ll make it the next two months without stroking out.

[Front Ranger]

[Phil]

Did they? I would be curious to see last years if you have them.

 

Obviously not a great predictor, but they can still be good to see possible large scale seasonal patterns and where the mean trough positions might set up.

Possibly, but that assumes the model is correct. Last September, the model was forecasting a warm west/cold east winter, and the opposite verified.

 

Perhaps it was on track until the SSW. Same with the previous winter. But intraseasonal variability is an aspect of every winter..so there’s always going to be something.

[Front Ranger]

12z GFS is pretty dry and ridge-like days 6-10.

 

#autofail

[Kayla]

Possibly, but that assumes the model is correct. Last September, the model was forecasting a warm west/cold east winter, and the opposite verified.

 

Perhaps it was on track until the SSW. Same with the previous winter. But intraseasonal variability is an aspect of every winter..so there’s always going to be something.

 

The above maps are snowfall anomalies though, not temps. The ECMWF seasonal is predicting a lot of NPAC blocking leading to below average temps in the NW while being rather dry which is not surprising given the blocking it's predicting.

 

At this point, I feel like it's a decent forecast for the NW. Below average temps with below average precip. Of course in the PNW lowlands it only takes a couple storms to turn a cold, dry winter into a great, snowy one. 

[Deweydog]

I can definitely see this being one of those winters where snow pack could be practically non-existent in the metro area going into spring.

 

Warm ups and cool downs...

[Phil]

[ShawniganLake]

Snowfall anomaly maps seem particularly useless for the PNW lowlands. 1 hard hitting overrunning event could get a lot of places to average on the season in 1 6-12 hour event. It could be followed by a quick warm up and 12 hours later the snow would be all gone.

[Phil]

The above maps are snowfall anomalies though, not temps. The ECMWF seasonal is predicting a lot of NPAC blocking leading to below average temps in the NW while being rather dry which is not surprising given the blocking it's predicting.

 

At this point, I feel like it's a decent forecast for the NW. Below average temps with below average precip. Of course in the PNW it only takes a couple storms to turn a cold, dry winter into a great, snowy one.

Well I’m saying the forecast last winter was warm/dry. The problem is the resolution of those maps is low/smoothed over by this vendor, and it’s an large ensemble.

 

A cold/dry winter could easily feature above normal snowfall in the lowlands but a crappy snowpack in the mountains, and the latter is what the ensemble would be picking up on because it would be the stronger/more consistent signal throughout the ensemble mean, which is then smoothed over by this vendor (rather inappropriately in some places, I might add).

[TacomaWaWx]

Little break in the activity currently. 0.17” so far since 6:30am, 55 outside. Up to 1.56” for the month which is officially the wettest September since 2014, when we had 2.41”.

[ShawniganLake]

0.37” here this morning

[Kayla]

Well I’m saying the forecast last winter was warm/dry. The problem is the resolution of those maps is low/smoothed over by this vendor, and it’s an large ensemble.

 

A cold/dry winter could easily feature above normal snowfall in the lowlands but a crappy snowpack in the mountains, and the latter is what the ensemble would be picking up on because it would be the stronger/more consistent signal throughout the ensemble mean, which is then smoothed over by this vendor (rather inappropriately in some places, I might add).

 

Then it did a pretty good job overall IMO. That SSW event was the only thing that "saved" the PNW lowlands with its late Feb heroics. 

 

I agree with you on the rest of this and the smoothing factor. 

[Omegaraptor]

PDX record highest average low in September is 56.7°F set in 2013.

 

So far, this month is at 60.4°F.

[jcmcgaffey]

Well I’m saying the forecast last winter was warm/dry. The problem is the resolution of those maps is low/smoothed over by this vendor, and it’s an large ensemble.

 

A cold/dry winter could easily feature above normal snowfall in the lowlands but a crappy snowpack in the mountains, and the latter is what the ensemble would be picking up on because it would be the stronger/more consistent signal throughout the ensemble mean, which is then smoothed over by this vendor (rather inappropriately in some places, I might add).

. Our winter was overall warm and dry outside of February but pretty close to normal. I think the long range maps were fairly accurate.

[Jesse]

Snowfall anomaly maps seem particularly useless for the PNW lowlands. 1 hard hitting overrunning event could get a lot of places to average on the season in 1 6-12 hour event. It could be followed by a quick warm up and 12 hours later the snow would be all gone.

Yeah, was thinking the same thing.

[Phil]

Uh, yeah...that’s a lot of subsidence over the Indo-Pacific. It’s an intraseasonal state (or the amplification of a background state by such) but this might be enough to put the kibosh on any -ENSO attempt in the long run, even with future propagation. Should see westerlies cranking over much of the tropical Pacific for the next 2 weeks at least, following the first WWB last week/weekend.

 

[Deweydog]

Looks like a stained glass window at some church.

 

Jesus likes snow. Has to be a good sign!

[SilverFallsAndrew]

PDX record highest average low in September is 56.7°F set in 2013.

 

So far, this month is at 60.4°F.

 

Well it led to good things later on. 

[SilverFallsAndrew]

This front/rainfall has been extremely underwhelming today. Just around 0.10" most places in NW Oregon. 

[Jesse]

Today’s front seems a lot less organized than Sunday’s, so far.