February 2014 in the PNW

[Dadio]

This is how the WRF is modeling the snowstorm late this weekend and into Monday. No way to know if it will happen, although I am pretty confident that cyclogenesis will occur off the BC coast with the amount of cold air coming off the interior.

 

See http://theweatherforums.com/index.php?/topic/125-brown-and-younkin-1970-850-mb-lows-and-heavy-snow/.

 

http://oi60.tinypic.com/e1eqab.jpg

Thanks for the wonderful map.

[HighlandExperience]

Nam looks good at 84 hr. Looks like it is about to drop a bomb on us.

 

Looks good for W. Washington. This might be real this time...

 

http://mag.ncep.noaa.gov/data/nam/18/nam_namer_084_precip_ptot.gif

[brody]

Nam looks good at 84 hr. Looks like it is about to drop a bomb on us.

Sure does but is it the bomb or Da Bomb?

[Karl Bonner]

Sure does but is it the bomb or Da Bomb?

A very sick, phat and dope bomb let's hope! 

[χιόνι (chióni)]

I'm having flashbacks of 1996. 

[luvssnow_spokane]

I'm having flashbacks of 1996. 

I am starting to have a panic attack... The good kind...

 

I just logged in here and read the last 4 pages... one word -- "OMG!"

[Thunderhill]

Then the 18z crapped on everyone's snow parade.

[brody]

Then the 18z crapped on everyone's snow parade.

and it has that reputation for a reason 

[brody]

I am starting to have a panic attack... The good kind...

 

I just logged in here and read the last 4 pages... one word -- "OMG!"

I think you meant SNOMG

[Thunderhill]

and it has that reputation for a reason 

Agreed but sometimes it has a knack for picking up on new trends...seen it before...it's such a drastic difference in the low placement...it's a bit more believable vs the Dec 2008 redux that the 12z showed.

[Phil]

Toss the 18z GFS. I don't buy the idea that we'll see the CKW go through metamorphosis and become an MJO wave.

 

But I've been wrong many times before.

[Thunderhill]

Agreed but sometimes it has a knack for picking up on new trends...seen it before...it's such a drastic difference in the low placement...it's a bit more believable vs the Dec 2008 redux that the 12z showed.

Sorry, should clarify, the low placement being just perfect and triple point just south of PDX...not an all out Dec 2008 redux

[FroYoBro]

I love how the WRF shows my location getting completely screwed lol.

LOLOLOL

[Phil]

Once again the Euro ensemble mean is colder than the operational.

The maps I have show 850's @ SEA bottoming out near -9C.

[seattleweatherguy]

Looks good for W. Washington. This might be real this time...

 

http://mag.ncep.noaa.gov/data/nam/18/nam_namer_084_precip_ptot.gif

do not know if i can agree with this map. it would be good for the entire west coast. even  cali gets pounded.

[Timmy Supercell]

65 degrees right now in Klamath Falls. Just 1 degree away from matching a record high (66 in 1992).

 

I'm loving this Spring!! Err.. I mean late Winter...

[HighlandExperience]

Seattle NWS discussion today is rather bland and boring.

 

.LONG TERM...THE GFS IS MORE AGGRESSIVE THAN THE EURO IN BRINGING
COLD AIR SOUTH THROUGH WASHINGTON BUT NEITHER MODEL SHOWS A FULL
FLEDGED ARCTIC OUTBREAK. MOST OF THE COLD AIR SLIPS SOUTHEAST INTO
EASTERN WASHINGTON AND POINTS EAST. THERE ARE ALSO DRIBS AND DRABS
OF PRECIPITATION THROUGH THE EXTENDED AND A MODEL BLEND SHOWS LOW
CHANCE POPS. HAVE USED THESE LOW CHANCE POPS THROUGH THE EXTENDED
AND COOLED THINGS OFF A BIT. THIS HAS INTRODUCED A CHANCE OF RAIN OR
SNOW TO THE HIGHER BITS OF THE LOWLANDS THROUGH ABOUT MONDAY. SOME
WARMING OCCURS TUESDAY.

[Brian_in_Leavenworth]

Seattle NWS discussion today is rather bland and boring.

 

.LONG TERM...THE GFS IS MORE AGGRESSIVE THAN THE EURO IN BRINGING

COLD AIR SOUTH THROUGH WASHINGTON BUT NEITHER MODEL SHOWS A FULL

FLEDGED ARCTIC OUTBREAK. MOST OF THE COLD AIR SLIPS SOUTHEAST INTO

EASTERN WASHINGTON AND POINTS EAST. THERE ARE ALSO DRIBS AND DRABS

OF PRECIPITATION THROUGH THE EXTENDED AND A MODEL BLEND SHOWS LOW

CHANCE POPS. HAVE USED THESE LOW CHANCE POPS THROUGH THE EXTENDED

AND COOLED THINGS OFF A BIT. THIS HAS INTRODUCED A CHANCE OF RAIN OR

SNOW TO THE HIGHER BITS OF THE LOWLANDS THROUGH ABOUT MONDAY. SOME

WARMING OCCURS TUESDAY.

The Spokane one is very detailed, I like the different scenarios they put out there, and the confidence level.   I know most of you don't live in the area covered by the Spokane NWS, but it is still a good read (and a long one too):

 

 

"The weather will trend very active starting Thursday night and continue into Friday. The Polar Low sprawled across a majority of Canada will dig into what's left of the ridge and swing into the Inland NW. This will usher an arctic front into the region, supply a means of strong lift, and bring the potential for a very windy period. There are still considerable differences amongst the models regarding the trajectory of the midlevel wave and we generally preferred a SREF/GFS solution with signs that the ECMWF is trending this direction. Unlike most arctic fronts that typically pass through with generally dry, windy conditions a moist air mass will be in place. Lift along the front coupled with modest Q-vector convergence should lead to increasing precipitation chances for much of Thursday night and Friday. Precipitation type should transition from rain to snow for most locations and the potential for a few inches of snow will be there...but carry low confidence and will depend if the upper- level wave stalls or continues to press south which would shut off precipitation quickly...or as snow levels fall back to valley floors. Hopefully, models match up a bit better tomorrow and we can achieve more confidence with potential snowfall amounts. The forecast is leaning toward a snowier solution but spread at locations like Spokane range from o.2 to 5.0" per SREF plume diagrams.

 

A bigger concern will be the potential for strong, damaging northeast winds. GFS forecast pressure gradients between Kalispell and Portland to tighten between 25-30mb Friday night. The Purcell Trench, West Plains, and Columbia Basin will get the brunt of the winds which could increase between 15-30 mph with gusts in excess of 40 mph. Ridgetops across the ID Panhandle could be facing gusts in excess of 50 mph. /sb

 

Saturday through Tuesday...A wintry weather pattern is expected in the extended period with arctic air returning to the Inland Northwest. A high amplitude upper ridge along 140W is expected to allow an arctic air mass over north Central Canada to plunge southwest into the Inland Northwest. This arctic air mass should result in mainly dry weather although uncertainty exists as described below.

*Temperatures: Well below average Confidence: Above average

 

The GFS and ECMWF are in good agreement that 850mb temperatures Saturday and Sunday will plummet into the -15 to -23C range with the coldest values over the Idaho Panhandle. Confidence in precise values however is low due to uncertainty with cloud cover. Temperatures should begin to gradually moderate Monday and Tuesday.

 

*Wind: Breezy to windy conditions for much of the Inland NW Saturday creating very cold wind chill values

 

Confidence: Above average

 

GFS and ECMWF show at 1040-1048mb arctic air over southern Alberta and a 1000mb surface trough along the Oregon coast. This will create a strong pressure gradient along with strong cold air advection. The Purcell Trench will likely see sustained winds 20-30 mph with higher gusts which includes Sandpoint and Coeur D'Alene. This combined with the cold temperatures will create wind chill values as low at -10 to -20F. Elsewhere breezy winds across the Spokane area and Columbia Basin will result in very cold conditions as well.

 

*Precipitation: Most likely a drier pattern should develop Saturday or Saturday night.

 

Confidence: Below average

 

Models are having a difficult time with the precise pattern with the arctic air intrusion. Several GFS Ensemble members carve a trough more aggressive over southwest British Columbia with increased frontogenesis over the weekend resulting in areas of snow over the Inland Northwest. The UKMET extension and the 18z NAM out through Friday night is more in support of this scenario. The operational GFS shows this scenario for Saturday before the very cold/dry arctic air mass takes over with drier conditions Saturday night through Monday. The GEM shows similarities to the GFS although is fairly dry. The ECMWF maintains a deep northerly flow with the Inland Northwest free of precip Saturday through Monday night. Given that most of the operational models show a drier pattern forecast favors this. However With the GFS Ensemble POPs at 40-60% each 12 hour period precipitation chances have been trended upward to 20-30% just in case some of the more unsettled solutions pan out. JW"

[Weather101]

Seattle NWS discussion today is rather bland and boring.

 

.LONG TERM...THE GFS IS MORE AGGRESSIVE THAN THE EURO IN BRINGING

COLD AIR SOUTH THROUGH WASHINGTON BUT NEITHER MODEL SHOWS A FULL

FLEDGED ARCTIC OUTBREAK. MOST OF THE COLD AIR SLIPS SOUTHEAST INTO

EASTERN WASHINGTON AND POINTS EAST. THERE ARE ALSO DRIBS AND DRABS

OF PRECIPITATION THROUGH THE EXTENDED AND A MODEL BLEND SHOWS LOW

CHANCE POPS. HAVE USED THESE LOW CHANCE POPS THROUGH THE EXTENDED

AND COOLED THINGS OFF A BIT. THIS HAS INTRODUCED A CHANCE OF RAIN OR

SNOW TO THE HIGHER BITS OF THE LOWLANDS THROUGH ABOUT MONDAY. SOME

WARMING OCCURS TUESDAY.

They always do that this far away there start jumping on the band wagon by Thursday if the models still show it.

[epiceast]

Looks good for W. Washington. This might be real this time...

 

http://mag.ncep.noaa.gov/data/nam/18/nam_namer_084_precip_ptot.gif

Remember it's just the NAM... This models is even lousier than the GFS.

[AnthonyC]

The 18Z NAM is just about to be awesome at the end of the run...

 

I'm noticing the upper-level pattern is getting better and better with each model run, which is good for us.  Definitely an omega block in Alaska, and a lot of the model runs are starting to show more of a consolidated offshore ridge.  The pattern starts retrograding tomorrow...how far west and south that goes remains to be scene...

[Canadian guy]

Cold

http://www.wetterzentrale.de/pics/MT8_Vancouver_Kanada_ens.png

[SilverFallsAndrew]

http://www.wetterzentrale.de/pics/MT8_Portland_Oregon_USA_ens.png

[AnthonyC]

Cold

 

WOW!!

 

Like I've mentioned before, the 1st week of March is notorious for arctic cold/lowland snow.  It's too bad the first week of January isn't the same...at least anymore.

[AnthonyC]

Can someone post the SEA one please?

[SilverFallsAndrew]

http://www.wetterzentrale.de/pics/MT8_Seattle_USA_ens.png

[Jesse]

Wow, 18z ensembles are crazy.

[Skagit Weather]

It would be absolutely amazing to get another arctic outbreak this winter, especially if it spread snow throughout the I-5 corridor. My 2" is now gone so I guess I will be starting with a blank slate if it does snow again. Sunny with a high of 46F today after a low of 31.5F.

[Jesse]

It's been mostly cloudy, windy and chilly out here today. High of only 40 after a low of 35. The clouds have lifted a bit this afternoon, exposing a fresh coating of rime ice on the trees in the surrounding mountains.

[bainbridgekid]

I just realized something about the ensemble charts that makes the really cold ensemble means even more impressive.

 

If the mean "bottoms out" at, say, -10, the coldest that the average ensemble member actually gets is probably a couple degrees colder than that because they do not all have the center of the coldest air at the exact same time.

 

So for airmasses where the exact timing of the coldest anomalies is more up in the air, the mean won't get as cold despite equally strong ensemble support.

 

Looks to me like one of the reasons the Vancouver chart that has been posted gets so incredibly cold (-16) is that nearly all of the members are at their coldest point at nearly the same time. The Portland one on the other hand, has much more variation with the cold peaking in a larger range and some members bringing in significant warming (must be an overrunning event) right at the same time that the other members are at their coldest (March 3rd.)

 

Of course, the ensembles are also run at a lower resolution which gives them terrain issues making them prone to bringing arctic air in too quickly which probably cancels out much of the underestimation caused by timing issues.

[snow_wizard]

WOW!!

 

Like I've mentioned before, the 1st week of March is notorious for arctic cold/lowland snow.  It's too bad the first week of January isn't the same...at least anymore.

It is funny how early March has a lot more blasts under it's belt than late February. Kind of like how late October has a lot more than early November. Makes no sense.

[snow_wizard]

I just realized something about the ensemble charts that makes the really cold ensemble means even more impressive.

 

If the mean "bottoms out" at, say, -10, the coldest that the average ensemble member actually gets is probably a couple degrees colder than that because they do not all have the center of the coldest air at the exact same time.

 

So for airmasses where the exact timing of the coldest anomalies is more up in the air, the mean won't get as cold despite equally strong ensemble support.

 

Looks to me like one of the reasons the Vancouver chart that has been posted gets so incredibly cold (-16) is that nearly all of the members are at their coldest point at nearly the same time. The Portland one on the other hand, has much more variation with the cold peaking in a larger range and some members bringing in significant warming (must be an overrunning event) right at the same time that the other members are at their coldest (March 3rd.)

 

Of course, the ensembles are also run at a lower resolution which gives them terrain issues making them prone to bringing arctic air in too quickly which probably cancels out much of the underestimation caused by timing issues.

There are members that are warm biased also. It's supposed to all balance out. One of the more surprising things today is the ECMWF ensemble is actually closer to looking like the GFS operational runs as opposed to the ECMWF operational. The GFS has had some bouts with greatness this winter. Last weekend was probably the biggest bust in months for it.

[Timmy]

Wow, 18z ensembles are crazy.

Totes cray

[Phil]

http://www.wetterzentrale.de/pics/MT8_Seattle_USA_ens.png

Remember that the OP GFS handles terrain-induced bottling better than the ensembles. Won't be a super-significant factor but given the trajectory of the airmass, it's important to factor in.

[GHweatherChris]

Remember that the OP GFS handles terrain-induced bottling better than the ensembles. Won't be a super-significant factor but given the trajectory of the airmass, it's important to factor in.

I am just glad the ensembles show at least a little precip during the coldest period.  That bodes well for us as of now.

[Phil]

I am just glad the ensembles show at least a little precip during the coldest period. That bodes well for us as of now.

I agree, the QPF is encouraging, and it should be cold enough for snow at least N of the WA/OR border above 200ft. I'm just weary of the way the GEFS handles the Cascades, and would put more trust in the GGEM/ECMWF at this stage.

[bainbridgekid]

00z NAM is a thing of beauty. Snow Friday night already for the North Interior and a buttload of arctic air moving our way on this run.

 

http://mag.ncep.noaa.gov/data/nam/20140226/00/nam_namer_084_1000_500_thick_s.gif

[SilverFallsAndrew]

Yeah the ensembles are outrageous. 

[pscz1140]

The NAM is looking tastier than a lobster and SweeTart sandwich.

 

Too bad it's the NAM.

[MR.SNOWMIZER]

The Spokane one is very detailed, I like the different scenarios they put out there, and the confidence level.   I know most of you don't live in the area covered by the Spokane NWS, but it is still a good read (and a long one too):

 

 

"The weather will trend very active starting Thursday night and continue into Friday. The Polar Low sprawled across a majority of Canada will dig into what's left of the ridge and swing into the Inland NW. This will usher an arctic front into the region, supply a means of strong lift, and bring the potential for a very windy period. There are still considerable differences amongst the models regarding the trajectory of the midlevel wave and we generally preferred a SREF/GFS solution with signs that the ECMWF is trending this direction. Unlike most arctic fronts that typically pass through with generally dry, windy conditions a moist air mass will be in place. Lift along the front coupled with modest Q-vector convergence should lead to increasing precipitation chances for much of Thursday night and Friday. Precipitation type should transition from rain to snow for most locations and the potential for a few inches of snow will be there...but carry low confidence and will depend if the upper- level wave stalls or continues to press south which would shut off precipitation quickly...or as snow levels fall back to valley floors. Hopefully, models match up a bit better tomorrow and we can achieve more confidence with potential snowfall amounts. The forecast is leaning toward a snowier solution but spread at locations like Spokane range from o.2 to 5.0" per SREF plume diagrams.

 

A bigger concern will be the potential for strong, damaging northeast winds. GFS forecast pressure gradients between Kalispell and Portland to tighten between 25-30mb Friday night. The Purcell Trench, West Plains, and Columbia Basin will get the brunt of the winds which could increase between 15-30 mph with gusts in excess of 40 mph. Ridgetops across the ID Panhandle could be facing gusts in excess of 50 mph. /sb

 

Saturday through Tuesday...A wintry weather pattern is expected in the extended period with arctic air returning to the Inland Northwest. A high amplitude upper ridge along 140W is expected to allow an arctic air mass over north Central Canada to plunge southwest into the Inland Northwest. This arctic air mass should result in mainly dry weather although uncertainty exists as described below.

*Temperatures: Well below average Confidence: Above average

 

The GFS and ECMWF are in good agreement that 850mb temperatures Saturday and Sunday will plummet into the -15 to -23C range with the coldest values over the Idaho Panhandle. Confidence in precise values however is low due to uncertainty with cloud cover. Temperatures should begin to gradually moderate Monday and Tuesday.

 

*Wind: Breezy to windy conditions for much of the Inland NW Saturday creating very cold wind chill values

 

Confidence: Above average

 

GFS and ECMWF show at 1040-1048mb arctic air over southern Alberta and a 1000mb surface trough along the Oregon coast. This will create a strong pressure gradient along with strong cold air advection. The Purcell Trench will likely see sustained winds 20-30 mph with higher gusts which includes Sandpoint and Coeur D'Alene. This combined with the cold temperatures will create wind chill values as low at -10 to -20F. Elsewhere breezy winds across the Spokane area and Columbia Basin will result in very cold conditions as well.

 

*Precipitation: Most likely a drier pattern should develop Saturday or Saturday night.

 

Confidence: Below average

 

Models are having a difficult time with the precise pattern with the arctic air intrusion. Several GFS Ensemble members carve a trough more aggressive over southwest British Columbia with increased frontogenesis over the weekend resulting in areas of snow over the Inland Northwest. The UKMET extension and the 18z NAM out through Friday night is more in support of this scenario. The operational GFS shows this scenario for Saturday before the very cold/dry arctic air mass takes over with drier conditions Saturday night through Monday. The GEM shows similarities to the GFS although is fairly dry. The ECMWF maintains a deep northerly flow with the Inland Northwest free of precip Saturday through Monday night. Given that most of the operational models show a drier pattern forecast favors this. However With the GFS Ensemble POPs at 40-60% each 12 hour period precipitation chances have been trended upward to 20-30% just in case some of the more unsettled solutions pan out. JW"

This is one of the best forecast discussions I have seen. Awesome detail. Jesus, the Seattle office makes it sound like a few cold showers are possible. Not even talking much about trends or outcomes. I think they know many people read there discussions now and it is more like a forecast than a discussion. I have been reading them since I have had a computer and they never were this bland.