PNW November 2021 Wx Obs/Discussion

[GHweatherChris]

6 minutes ago, Phil said:

Lol. We’ve seen 10-12” of snow in the last 33 months. And just had three consecutive 70+ days. After a summer with 50+ days above 90°F.

You guys have done much better in recent years.

You have seen way more snow in total than that.

[snow_wizard]

I'm pretty hard pressed to remember any time we've had back to back AR events (this one and the one this weekend) in a short period of time since 1990.  This is a quite a rarity made even more impressive by the huge AR they had in CA a few weeks back also.

[snow_wizard]

3 minutes ago, SilverFallsAndrew said:

We have had nice November s followed by good winters. We’ve been torching for almost a month now, maybe it will eventually flip.

In Nina winters awful patterns in November very often lead to good winters in fact.

[Phil]

4 minutes ago, GHweatherChris said:

You have seen way more snow in total than that.

Nope. DCA has only seen 9.7” since February 2019. Here it’s more like a foot, maybe a little more.

Atrocious stretch, all things considered.

[TigerWoodsLibido]

Up to 63F. Smoking in my t shirt on the porch.

[Phil]

Tropical forcing analogs still look interesting in December, but now with a little more +EPO component by mid-December.

Not too far off from the mean state in 2007/08.

[smerfylicious]

2nd hand reports of some good lightning in downtown Seattle.

[Meatyorologist]

Surprise lightning storm here. Big bolt sniped me right overhead, what a surprise! I was out to watch the rain, didn’t expect any lightning.

[snow_wizard]

7 minutes ago, smerfylicious said:

2nd hand reports of some good lightning in downtown Seattle.

Pretty surprising.  I think I remember lightning in a case like this before and the NWS called it slantwise convection whatever that is.

[snow_wizard]

46 minutes ago, Phil said:

Tropical forcing analogs still look interesting in December, but now with a little more +EPO component by mid-December.

Not too far off from the mean state in 2007/08.

I hope you have analogs other than 2007.  I still say this one won't be as zonal as that winter.  There are important differences this year.

Looking at that map you posted it looks like the composite for 1970-71.

[smerfylicious]

32 and raining at Stevens Pass. Sad. Build up that snowpack!

[snow_wizard]

I ended up with 2.07" of rain for Thursday.  Quite impressively that is my second 2 inch day in the last two weeks.

[snow_wizard]

1 minute ago, smerfylicious said:

32 and raining at Stevens Pass. Sad. Build up that snowpack!

You can kiss most of the snow on the ground goodbye after this weekend.  This is classic behavior before a major cold wave though.

[snow_wizard]

The radar shows a lot more rain coming before it ends.

[snow_wizard]

No AR's in the fall of 2007.  That's a big difference right there.  This season is AR happy, and that normally equates to big cold later on.

Another huge difference between this and the fall of 2007 is 2007 didn't have the huge positive height anoms over much of Canada that we've seen over the past few weeks.  1970 had that.  I'm as stuck on 1970 as Phil is on 2007.

[smerfylicious]

4 minutes ago, snow_wizard said:

You can kiss most of the snow on the ground goodbye after this weekend.  This is classic behavior before a major cold wave though.

At least I'm apparently in the bullseye on the convergence zones next week. If I get a trace of snow, I'll take an unflattering picture of it.

[snow_wizard]

The trajectory of this moisture plume is much more out of the west than the last AR we had.  This is out of the 1990 playbook.  I still remember that autumn in vivid detail.  The Arctic blast that came later was incredible.

[Gradient Keeper]

20 minutes ago, Meatyorologist said:

Surprise lightning storm here. Big bolt sniped me right overhead, what a surprise! I was out to watch the rain, didn’t expect any lightning.

We can't rule out rogue isolated strikes anywhere from NW Oregon up through Western Nebraskington. To my surprise we have some MUCAPE in play. This coupled with modestly steep 700-500mb lapse rates of 6.5C/km(especially when considering a subtropical air mass), and 40-60kts 0-6km deep layer shear.

[Gradient Keeper]

7 minutes ago, snow_wizard said:

The trajectory of this moisture plume is much more out of the west than the last AR we had.  This is out of the 1990 playbook.  I still remember that autumn in vivid detail.  The Arctic blast that came later was incredible.

Yeah I agree this Fall is unfolding very well in our favor and if you factor in the number of mega deep lows and ARs something memorable is in the offing for us.

[Gradient Keeper]

Mesoscale Precipitation Discussion

 

Mesoscale Precipitation Discussion 1126
NWS Weather Prediction Center College Park MD
426 AM EST Fri Nov 12 2021

Areas affected...Northwest OR...Western WA
Concerning...Heavy rainfall
Valid 120925Z - 121800Z

SUMMARY...Atmospheric river conditions will continue to produce
heavy rainfall through the mid-morning hours for much of western
Washington and northwest Oregon.  An additional 1 to 3 inches of
rainfall for orographically favored locations will lead to
additional instances of enhanced run-off concerns and possible
flooding.

DISCUSSION...Recent GOES-17 satellite imagery continues to portray
a corridor of enhanced moisture that is associated with an
atmospheric river oriented from WSW to ENE, originating from near
30 degrees north over the central Pacific.  Regional Doppler
radars indicate a substantial area of moderate to heavy showers
moving across western Washington and northwest Oregon,
particularly across the coastal ranges and the western slopes of
the Cascades.  It is these areas where the flow will be orthogonal
to the terrain and the greatest rainfall totals realized.

A strong west-southwest low-level jet on the order of 50 mph, in
combination of IVT values of 600-800 kg/m/s and PWs approaching
1.5 inches within the moisture plume, will sustain widespread
moderate to heavy rainfall through sunrise, followed by a gradual
abatement in intensity going through the middle to late morning
hours.  The latest CAM guidance is suggesting the potential for up
to 3 inches of additional rainfall through 18Z, particularly with
the HRRR and WRF. 

Given the saturated soils with 2-4 inches of rainfall over the
past 24 hours, there will be growing concerns for runoff problems
and localized flooding.  Some of the area burn scars will be more
sensitive to these heavier rains and should be closely monitored.

[Cloud]

11 minutes ago, DJ Droppin said:

Mesoscale Precipitation Discussion

 

Mesoscale Precipitation Discussion 1126
NWS Weather Prediction Center College Park MD
426 AM EST Fri Nov 12 2021

Areas affected...Northwest OR...Western WA
Concerning...Heavy rainfall
Valid 120925Z - 121800Z

SUMMARY...Atmospheric river conditions will continue to produce
heavy rainfall through the mid-morning hours for much of western
Washington and northwest Oregon.  An additional 1 to 3 inches of
rainfall for orographically favored locations will lead to
additional instances of enhanced run-off concerns and possible
flooding.

DISCUSSION...Recent GOES-17 satellite imagery continues to portray
a corridor of enhanced moisture that is associated with an
atmospheric river oriented from WSW to ENE, originating from near
30 degrees north over the central Pacific.  Regional Doppler
radars indicate a substantial area of moderate to heavy showers
moving across western Washington and northwest Oregon,
particularly across the coastal ranges and the western slopes of
the Cascades.  It is these areas where the flow will be orthogonal
to the terrain and the greatest rainfall totals realized.

A strong west-southwest low-level jet on the order of 50 mph, in
combination of IVT values of 600-800 kg/m/s and PWs approaching
1.5 inches within the moisture plume, will sustain widespread
moderate to heavy rainfall through sunrise, followed by a gradual
abatement in intensity going through the middle to late morning
hours.  The latest CAM guidance is suggesting the potential for up
to 3 inches of additional rainfall through 18Z, particularly with
the HRRR and WRF. 

Given the saturated soils with 2-4 inches of rainfall over the
past 24 hours, there will be growing concerns for runoff problems
and localized flooding.  Some of the area burn scars will be more
sensitive to these heavier rains and should be closely monitored.

Did someone drew a thumb up?! How dare them! We're getting flooded here man! 

[Tyler Mode]

Yesterday I recorded 2.37" of rain at my station which sets an ALL TIME daily record! It's only the 4th time I've recorded over 2" of rain in one day.

[FroYoBro]

Looks like Portland is the target for this next band of rain. Will probably be some urban flooding tomorrow morning. 

[Gradient Keeper]

6z GFS Day 4 (Past 4 runs) Trough digging a bit better. If this trend continues it could be a bit chilly.

[Cloud]

56/45 with 1.26" of rain day for yesterday at SEA. Fell slightly short of daily record of 1.48" from 1973. 

Now well over 4" for the month. 

[TigerWoodsLibido]

Still 60F out there. Warm fall so far. Maybe we can finish above normal in precip for the month because the elusive colder and wetter than normal month appears to be perpetually disallowed by Mother Nature.

[Gradient Keeper]

Great 6z run! Wet, A lot of Mt. Snow, chilly air masses, and mega cold building from central BC/AB northward!

[Cloud]

It's also been astonishingly wet since the new water year start (Oct. 1). 

Now over 10" of rain at 10.13" as of yesterday, 4.01" above normal.  Yup.... over 10" of rain since Oct 1. 

Normal period is 1991 to 2020. 

More to come it seems. 

[Cloud]

5 minutes ago, DJ Droppin said:

Great 6z run! Wet, A lot of Mt. Snow, chilly air masses, and mega cold building from central BC/AB northward!

Randy @MossManis getting in on the action! 6" for Mt. Vernon!

[Cloud]

This is back to back 6z runs that shows some cool/cold in the 7-10 range. Keep it moving forward. 

[Gradient Keeper]

516 thickness contour down into southern BC! C'MON!!!!

[Cloud]

2 minutes ago, DJ Droppin said:

516 thickness contour down into southern BC! C'MON!!!!

If anything, take it as a warning shot going forward.

[Gradient Keeper]

2:50 AM Radar Update

It appears the AR is focused at PDX metro tonight as rain continues to develop and quickly increase in intensity. Very heavy rain is streaming into the area.

[Gradient Keeper]

Just now, Cloud said:

If anything, take it as a warning shot going forward.

Check out the progression of arctic air into BC/AB. Day 4-8. 850s -33c. It makes me think, "what IF?" and if we had a less progressive pattern we would be scoring big time! It's a matter of time!

 

[Gradient Keeper]

I have to get some rest. Onto fun 12z runs!

12z GFS in 4 hours 39 minutes

12z ECMWF in 6 hours 49 minutes

[Cloud]

4 minutes ago, DJ Droppin said:

Check out the progression of arctic air into BC/AB. Day 4-8. 850s -33c. It makes me think, "what IF?" and if we had a less progressive pattern we would be scoring big time! It's a matter of time!

 

There's ALWAYS something. But it's only a matter of time before the Pacific shuts down and hopefully we'll get the goodies. BELIEVE. 

[TigerWoodsLibido]

Down to 59F. Having seizures now so I'm gonna hit the hay. Hopefully the morning GFS can show something meaningful.

[Meatyorologist]

18 minutes ago, TigerWoodsLibido said:

Down to 59F. Having seizures now so I'm gonna hit the hay. Hopefully the morning GFS can show something meaningful.

Hoping for a good 12z run! Take care of yourself man 

[Gradient Keeper]

If we were into late November or December I would look for jet suppression and a cold wave as it often occurs after this extremely wet pattern with ARs ends, but I don't know this early in the Fall. By the way for PDX metro insanely wet out there this morning. Moderate to heavy rain continues with a breezy to at times gusty south wind thrown in the mix.

 

5:24 AM Radar Update

[Gradient Keeper]