Saturday, October 1, 2016

A Weakening BLOB

Nothing seems to intrigue folks more than the BLOB, the area of warm water over the northeast Pacific.  Since this blog provides cutting-edge science to its readers, I am going to provide a first:  a BLOB forecast.

First, I have major news:  the BLOB has already begun to weaken, as illustrated by maps of sea surface temperature (SST) anomaly (difference from normal) on Sept 16th and 29th.


But this is just the start.   The BLOB is associated with persistent high pressure over the eastern Pacific, since high pressure produces weaker winds and less stirring of cold water to the surface.   And high pressure also does other favorable things with the ocean currents.

The BLOB revved up over the summer because of persistent high pressure, something illustrated in the following map, which shows the upper level (500 hPa) height anomaly (difference from normal) for the past 90 days. You see the orange color (highest heights than normal) over the NE Pacific?  That is what did the job.


But recently that has changed.   Here is the same type of map for the last 7 days...lower than normal heights/pressure has moved in (blue colors).  Bad for BLOB.

Turning to the forecast, lets look at ensemble forecasts (actually the average of many forecasts) for the same field (differences from climatology aloft) at a few times in the future (48 h, 120h, 336 h).  Lots of blue and purple, which denotes troughing (low pressure)--just the opposite of what strengthens the BLOB.



Finally, the National Weather Service runs a coupled atmosphere/ocean model called CFS and here are its forecasts of sea surface temperature anomalies for the next four weeks.  The sea surface is cooling and BLOB is dying.




I know this analysis will bring sadness to BLOB lovers, but I have to be honest.  The BLOB is going to weaken over the next few weeks, something that should bring joy to Northwest snow lovers.








16 comments:

Michael Snyder said...

Population has increased and traffic is worse than 2008. With all the new people living here is it just me or does anyone else cringe when you think of what would happen to the Seattle Metro in a Severe Winter storm?

I've been here my whole life and I assume it will be like watching an all too real reality show if we get a Winter like 1989, 1990, 1996, 2008, etc...

But still how I wish for snow!

Rory said...

Blob can't disappear fast enough!

windlover said...

Yeeesssssss!!!!!

Buddy said...

Scott Sistek stated the warmest of the water is only 25m deep. Let's all row out there and stir it up.

Eric Blair said...

Awesome news, thank you again for not buying into the hype when the dreaded "blob" was allegedly coming back to cause more nightmarish weather for the NW during this Summer. You stated that while it had re - emerged somewhat, it was not like the prior summers of 2015 and 2014. Once again, this site is an oasis of sanity and objectivity.

Steve Rosenow said...

I have to say I'm a bit saddened to read this.

Astronomers on the west side of the state have sure taken a heck of a beating in the last few years. It'd sure be nice to have a summer and winter where we don't have to fight the marine layer invading every night and in the winter, it'd be nice to have some clear skies for once (which is what this so-called BLOB brings us).

Last winter, I barely opened up my observatory. I'd like to be able to use my observatory in Shelton for a change.

Bruce Nourish said...

Michael -- I'd just take the light rail. Problem solved.

mmjustus said...

Yay! We want a *proper* winter this year.

tracksdc89 said...

Would this mean a wetter or a dryer sustained pattern? I know it's neither fashionable nor trendy to hope for the former, although I hope (at least) not to be alone in preferring glowingly green surroundings as opposed to the current eyesore-esque dead-brown state our grass has been since late April. It's high time to finally get our green back.

Pete said...

I say good riddance! The blob and high pressure are the enemies of powder lovers!

Weatherfreak said...

Great news Cliff! Will be fun to watch this thing DIE a silent death. Would love to see a return to a cold PDO and some La Nina winters. It's been awhile...

Unknown said...

Agreeing with the above. Ready for proper winters, for a change. That said, looking at the CPC maps, it's looking warm through the end of the year, followed by "equal chances" warmer/colder or wetter/dryer, and then things warm up again through next fall. Hoping they're wrong (granted, they're talking about averages), and we get a snowy winter for a change.

Bryan Black said...

Now we just need to have an enormous trough of modified arctic air hit us from the east in a mountain wave event at the same time as an atmospheric river slams into us from the west. Several feet of snow in that one as long as the cold air keeps pulling from the east and you stay in the cold sector of the low.

Craig said...

Well, you have made this prediction before ( https://cliffmass.blogspot.com/2014/10/halloween-tragedy-blob-is-meeting.html ) without it coming to pass so we will see if you do better this time.

Cliff Mass said...

craig... the blog DID weaken then. Later it restrengthened....that is what happens as ridging comes and goes....cliff

Rob said...

Die Blob Die... we want a stellar ski season! and it is kinda fun seeing Seattle trying to cope with snow on the ground...