The Cold Blob is here: what does this imply for this summer?

There is "The Force" and the "Dark Side of the Force"

There is matter and anti-matter.

And yes, there is Donald Trump and Hillary Clinton

All polar opposites.

But there is another contrasting pair that all meteorologists should be familiar with:

"The Warm Blob" and the "The Cold Blob"    Also known as the Blob and the Anti-Blob

This Blob blog will tell you about the current situation and correct some misconceptions in the public domain about this misunderstood creature of the Pacific.

Many of you know about the warm Blob, a persistent area of warm water over the eastern Pacific (see image for the sea surface temperature anomaly, difference from normal, for Feb-March 2014).  This was a very strong Blob, with localized eastern Pacific waters as much as 4-7F about normal.

 One to two years ago, the warm blob was evident and the media took a LOT of notice.   Some suggested it caused our warm weather.  Some said it was the result of global warming.  The truth is that the warm blob was the tail, not the dog, and was forced by persistent high pressure over the eastern Pacific.

Many Blob lovers were dismayed with a dramatic change during the last year, with the warm Blob disappearing and shockingly, a cold Blob taking its place.  But few in the media covered this radical shift (for reasons I will let each of you imagine).

Here is a map of sea surface temperature (SST) anomalies (again difference from normal) for a few days ago.  Blue is colder than normal.  A cold Blob is off the West Coast, with temperatures reaching roughly 1.5 C (~2.5F) colder than typical.  Enough to put a chill down your back.

Why the chilly eastern Pacific?

Because instead of the high pressure anomaly that was over the eastern Pacific during 2014 and 2015, the atmosphere switched to a low pressure anomaly (a persistent trough) during the past winter.  To prove this to you, here are the 3-month 500-hPa height anomalies (difference from average) for October to December and January to March (blue indicates lower than normal heights--think of it as low pressure).  Low pressure is associated with stormier conditions that mix up the upper ocean (bring colder water to the surface).

What do the latest computer model forecasts suggest for the cold BLOB?  Here is the forecast of the large international medium range ensemble system (IMME), providing the predicted SST anomalies for June, July, August.   The cold Blob is still there, but weakens, with most of the northeast Pacific being near normal.

So what does this imply about our summer weather?

Not much.   

The effects of the surface temperature of the Pacific on our air temperatures are very modest, something I have proven with a series of simulation experiments in which I exchanged the warm Blob temperatures with normal conditions.   Only cooled the region west of the Cascade crest by a few degrees.    So having slightly cooler temperatures offshore will not stop a heat wave, but might contribute to a slightly cooler summer.

I do have some good news for Blob lovers:  there will be a modern remake of the old movie classic, including "Snakes on the Plane" star Samuel L. Jackson.   I can see it now.....perhaps he will be a meteorologist.... I have had enough of those **** Blobs in the **** Pacific Ocean.  It will be marvelous.



from Cliff Mass Weather Blog http://ift.tt/2rjc3xG