September 2017 PNW Discussion Thread

[Kayla]

Anyone else worried about wildland firefighters and possible hypothermia coming up?

Actually yes thanks for mentioning!!

 

NWS out here is actually worried enough to voice the same concerns in their discussions.

[Front Ranger]

Joe Bastardi made a video post today, and he mentioned a pattern flip at the end of the month with abnormally low snow levels in the NW part of the US.

 

Did he talk much about his massive Irma bust? That guy is a clown.

[ShawniganLake]

Actually yes thanks for mentioning!!

 

NWS out here is actually worried enough to voice the same concerns in their discussions.

They cancelled some of the night shifts in central BC, too cold. The firefighters reported having to break ice to get things started first thing in the morning.

[Jesse]

They cancelled some of the night shifts in central BC, too cold. The firefighters reported having to break ice to get things started first thing in the morning.

I'm sure they are all praying for hot and dry weather to return.

 

That....or they are glad to see the signs of fall because it means the fire season will be over soon.

[Jesse]

Did he talk much about his massive Irma bust? That guy is a clown.

Lay off of Phil, man.

[wx_statman]

22.6c with 590 heights over SLE this afternoon. No wonder we hit 90+. 

[Front Ranger]

Lay off of Phil, man.

Phil is Bastardi?

[Jesse]

Phil is Bastard.

[stuffradio]

6Z GFS is really wet, 3+" of rain within a couple days next week.

[TT-SEA]

Meaning rainfall for everyone early next week...

 

[Front Ranger]

12z Euro is quite the cool run. No Indian Summer this year.

[TT-SEA]

12z Euro is quite the cool run. No Indian Summer this year.

Technically... Indian Summer is defined as a warm period after the first killing frost.   And I don't think the ECMWF run goes out 2 months through mid-November.   

 

Indian summer is a period of unseasonably warm, dry weather that sometimes occurs in autumn in the Northern Hemisphere. The US National Weather Servicedefines this as weather conditions that are sunny and clear with above normal temperatures, occurring late-September to mid-November.^[1] It is usually described as occurring after a killing frost.^[1]

[ShawniganLake]

Meaning rainfall for everyone early next week...

 

Victoria rain shadow. "vancouverislandsouth" will not be pleased.

[TT-SEA]

Victoria rain shadow. "vancouverislandsouth" will not be pleased.

He should move to Sitka.

[Front Ranger]

Technically... Indian Summer is defined as a warm period after the first killing frost.   And I don't think the ECMWF run goes out 2 months through mid-November.   

 

Indian summer is a period of unseasonably warm, dry weather that sometimes occurs in autumn in the Northern Hemisphere. The US National Weather Servicedefines this as weather conditions that are sunny and clear with above normal temperatures, occurring late-September to mid-November.^[1] It is usually described as occurring after a killing frost.^[1]

 

Growing up in the PNW, it meant summer weather in late September/early October. Killing frosts don't usually occur until mid October in most areas, anyway.

[Front Ranger]

GFS ensembles also suggest below normal temps for the PNW for the next couple weeks.

[TT-SEA]

Growing up in the PNW, it meant summer weather in late September/early October. Killing frosts don't usually occur until mid October in most areas, anyway.

 

So... a deep trough for 3-4 days in the middle of September means that it will be cold and rainy from now until November?  

[Phil]

Lay off of Phil, man.

I REFUSE TO BE A STATISTIC.

[Phil]

So... a deep trough for 3-4 days in the middle of September means that it will be cold and rainy from now until November?

No, but the termination of the off-equator WPAC forcing does imply a colder, troughier period lasting several weeks. It won't be nearly enough to erase the warm September anomaly, but it's the beginning of the transition into the winter circulation.

 

I don't see any signs of a warm/ridgy pattern returning until the second week of October, at earliest, unless I'm too slow again.

[Front Ranger]

So... a deep trough for 3-4 days in the middle of September means that it will be cold and rainy from now until November?  

 

No. There's just no sign of warmth for the foreseeable future.

 

And FWIW, most years that were warm/dry in the late September/early October period were +ENSO. There are exceptions, of course, but years transitioning to -ENSO tend to end "summer" earlier. 

[epiceast]

Technically... Indian Summer is defined as a warm period after the first killing frost.   And I don't think the ECMWF run goes out 2 months through mid-November.   

 

Indian summer is a period of unseasonably warm, dry weather that sometimes occurs in autumn in the Northern Hemisphere. The US National Weather Servicedefines this as weather conditions that are sunny and clear with above normal temperatures, occurring late-September to mid-November.^[1] It is usually described as occurring after a killing frost.^[1]

I think we might qualify for an Indian Summer after this Saturday or Sunday night.

[TT-SEA]

No, but the termination of the off-equator WPAC forcing does imply a colder, troughier period lasting several weeks. It won't be nearly enough to erase the warm September anomaly, but it's the beginning of the transition into the winter circulation.

 

I don't see any signs of a warm/ridgy pattern returning until the second week of October, at earliest, unless I'm too slow again.

 

You are always too slow.

 

And early to mid October would be a great time to have the PNW definition of Indian Summer.  

[epiceast]

You are always too slow.

 

And early to mid October would be a great time to have the PNW definition of Indian Summer.  

Yeah, I really wish we had an Indian Summer all of late august-early October, after a nice deep trough and a killing frost(as well as a fire killing rain) in early/mid august.

[WeatherArchive]

Warm today around 90F in the shade.    In the sun it's 99F. Humidity is 30%   The sky is yucked over. 

 

I have a regular mercury thermometer protected in the shade and an (exposed) junko weather station in the sun during the afternoon since there is no other spot. 

[WeatherArchive]

Yeah, I really wish we had an Indian Summer all of late august-early October(after a nice deep trough and a killing first in early/mid august).

Isn't Indian summer's only a synoptic situation east of the Rockies?   Usually you get your first hard freeze that kills crops then warmth returns sometimes for lengthy periods of times.

[Front Ranger]

Top 10 driest Sep/Oct combos for PDX: 1952, 1965, 1974, 1976, 1987, 1988, 1991, 1993, 2002, 2006.

 

Heavily skewed towards +ENSO (8/10).

[Phil]

Atlantic ACE is already the 7th highest on record. This image from @recretos on twitter correlates A/S/O Atlantic ACE to the following winter circulation (DJF):

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/3DB4A717-6EA5-4A11-9C54-7CC52BFE4C82_zpshccj2eck.jpg

 

While some of this is ENSO-related, the NAO signal speaks to a longer term relationship between the winter NAM and Atlantic tropical activity/AMO. This image is also attributed to @recretos:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/99A5CF88-E8F5-4836-A341-6D767B70393F_zpsrc89op1e.jpg

 

Note how higher Atlantic ACE tends to correlate to stronger polar blocking in the long run. Probably related to the MDR/IO SSTA/wind stress response to the wavetrain under a -NAM background. Short term it's less certain but worth noting.

[Phil]

The upward trend in the NAM (AO/NAO) since the 1970s does speak to something greater, however the Atlantic ACE does provide some level of subdecadal (and even seasonal) predictability, in this case.

[TT-SEA]

Top 10 driest Sep/Oct combos for PDX: 1952, 1965, 1974, 1976, 1987, 1988, 1991, 1993, 2002, 2006.

 

Heavily skewed towards +ENSO (8/10).

 

My local history guide (everyone's favorite) says there two likely paths from here... a complete descent into cold and rainy for fall (like off a cliff in 2012) or a period of variability with alternating periods of rainy and cool mixed with periods of dry and pleasant  Note that pleasant does not always mean warm as temperatures start becoming dependent on inversions pretty soon. Staying warm and dry is not really an option from what I have seen.

 

I really like seeing the deep trough showing up for next week.   It will bring some needed rain and end the fire season and its early enough to possibly avoid the cliff scenario in October.   

 

No science here.   Just what I have seen locally with a weak Nina following a long, dry summer.    

[Phil]

For analog fans, the only years w/ more Atlantic ACE (through today) are 1893, 1933, 1950, 1995, and 2004, and 2005.

[Phil]

This is also the first year I can remember where a good portion of the far northern Canadian Arctic remained snow covered through the summer.

 

Snowcover remains well above normal just about everywhere across the high latitudes.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/6CD905A2-C5CA-4643-9099-6668BB5D9B8F_zpszl6b5kla.png

[TT-SEA]

For analog fans, the only years w/ more Atlantic ACE (through today) are 1893, 1933, 1950, 1995, and 2004, and 2005.

 

 

I have heard great things about December of 1933.   

[wx_statman]

I have heard great things about December of 1933.   

 

WA state record for precip in a single month. Would be great!

[TT-SEA]

WA state record for precip in a single month. Would be great!

 

Records are made to broken.  

[Front Ranger]

My local history guide (everyone's favorite) says there two likely paths from here... a complete descent into cold and rainy for fall (like off a cliff in 2012) or a period of variability with alternating periods of rainy and cool mixed with periods of dry and pleasant  Note that pleasant does not always mean warm as temperatures start becoming dependent on inversions pretty soon. Staying warm and dry is not really an option from what I have seen.

 

I really like seeing the deep trough showing up for next week.   It will bring some needed rain and end the fire season and its early enough to possibly avoid the cliff scenario in October.   

 

No science here.   Just what I have seen locally with a weak Nina following a long, dry summer.    

 

I'd lean towards that. It does fit climo better than 2012 or last year for that matter.  

 

But definitely agree that the ridgy and warm patterns that have dominated since mid May are probably done for awhile.

[Jesse]

At least 86 at PDX. Another overachiever.

[wx_statman]

At least 86 at PDX. Another overachiever.

 

Not really though. It was 21.2c over SLE this morning...and highs were 91 at both SLE and EUG. I don't know why mets thought today would only be in the low 80's.

[Geos]

Nice day today. Made it to 74. Few clouds out there today (more over the Olympics), but quite a bit of sun as well.

[Jesse]

Not really though. It was 21.2c over SLE this morning...and highs were 91 at both SLE and EUG. I don't know why mets thought today would only be in the low 80's.

There's more that factors into the daily high than morning 850s, of course. I think many were anticipating cool NW flow to cap things off more quickly, earlier in the afternoon.

[wx_statman]

There's more that factors into the daily high than morning 850s, of course. I think many were anticipating cool NW flow to cap things off more quickly, earlier in the afternoon.

 

I dunno, today seemed destined for at least the mid 80's. Especially after the 63 degree low.