The Son of Blob is Back!

Yes, its back.

The Blob.   Or at least one of its offspring.

Remember, the BLOB is an area of anomalously warm water in the north Pacific.

If you dare to look, let me illustrate our scary situation.

Here is the sea surface temperature anomaly from normal for today.    A pool of warm water is found over the north Pacific and Gulf of Alaska, with some of it over 2C warmer than normal.  This is the signature of the "son of blob" (or "daughter of blob if you prefer")

Why such warm water?  Because there has been an amazingly persistent area of high pressure over the Gulf of Alaska.   To illustrate, let me show you a map of the average anomaly from normal conditions of the heights of the 500 hPa pressure surface (around 18, 000 feet) for the past 30 days.(see below).  Wow.

A very highly amplitude pattern.  You see the bright reds over the Gulf of Alaska?....that means high heights (equivalent to high pressure) over that area.  There is also a deep trough over the Rockies...that is why they have been getting unusually cold temperatures to the west of us. And another ridge over the eastern U.S--explains the persistent warmth there.

The sea level pressure difference from normal shows anomalously high sea level pressure over just the area where the sea surface temperatures were warm....the Gulf of Alaska.

This is no coincidence!  As shown by my colleague and BLOB meister Dr.  Nick Bond and his co-authors, persistent high pressure is associated with lighter winds.  Such light winds result in less mixing in the upper layer of the ocean, so less cooler water from below is mixed to the surface.

The result?  A warm water anomaly and the rebirth of the BLOB.  How long will BLOB Jr. last?  At least as long as we have persistent high pressure over the north Pacific.  As this point, it looks like things are evolving to a pattern with less high pressure offshore, so the BLOB should weaken.
Unless is doesn't!

from Cliff Mass Weather and Climate Blog https://ift.tt/2J0EDKZ