October 20, 2021

The Bomb Cyclone Offshore

 The next 24 hours are going to be meteorologically exciting as a powerful storm grows rapidly offshore.

And before I say more, let me make clear that the inland areas of the Northwest will NOT get a major blow from this.   Along the coast and particularly along the coast of Vancouver Island, this will be a significant event.

But this storm is remarkable for several reasons and thus is worthy of description.  And is predicted to be a bomb cyclone, in which the central pressure lowers by more than hPa in 24 h. 

The latest NOAA/GFS forecast for sea level pressure at 5 AM tomorrow morning, shows a deep low off our coast, with a central pressure of 956 hPa.   A very, very deep storm for our latitudes, and lower than some category 1 and 2 hurricanes.  If this storm had been shifted a few hundred miles eastward, the damage would have been terrible.   But it will not do this:   model solutions have converged, with little chance of an inland path.


The wind forecast for 5 PM tomorrow shows gusts reaching 50-60 knots off our coast, and even stronger near the low center.

And the Seattle Windwatch wind gust forecast for 11 AM tomorrow predicts 60-80 mph just off the coast, and 30-50 mph gusts along the Washington coast and over the western Strait of Juan de Fuca.  Not a good day to head out to sea.

The most extreme coastal winds will be along the northern coast of Vancouver Island, where 60-70 mph gusts (orange colors) are predicted around 11 AM.  This is the result of a strong pressure difference coupled with the high terrain near the coast.


If this storm pans out, it will be a remarkable success for numerical weather prediction, considering the difficulty of predicting the rapid intensification of a tropical system moving northward into the midlatitudes.  

Imagine.  

Predicting the path of a storm over thousands of miles, as it switches its energy sources (from warm water and tropical moisture to horizontal temperature differences) and structure (symmetric tropic storm with fronts to a highly asymmetric storm with fronts), while predicting radical changes it is strength....and doing it all correctly.... is an extraordinary feat.

A feat of prediction we could not have done two decades ago.

And to be a little controversial for a second, some of this extraordinary technology might be of value to other communities, such as those that do epidemiological prediction.  

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The Second Edition of My Northwest Weather Book is Now Available!

My new book is greatly improved and expanded over the first edition, with new chapters on the meteorology of Northwest wildfires and the weather of British Columbia.  A completely revamped chapter on the effects of global warming on our region.  And it has been brought up to date with recent weather events and the imagery is improved greatly.
 

Where can you get it?

Local bookstores, such as the University of Washington bookstore.  The UW Bookstore has just received several dozen copies.

Or secure a copy from the publisher:  UW Press.

Or Third Place Books in Lake Forest Park or Seattle.

And yes, there are online sellers like Amazon and Barnes and Noble.


October 19, 2021

Saving California

 California has experienced a very dry year, with the precipitation since January 1st well below normal in most of the state, with particularly dry conditions in the northern portion where several of the big reservoirs are located. Some areas are down as much as 15-20 inches!



And not surprisingly the reservoirs are generally quite low right now,  with a number down to roughly 35-40% of normal (see below).   Not good.

Making the situation more worrisome, a La Nina is a near certainty for this winter, which generally produces drier than normal conditions over central and southern CA.

But sometimes the atmosphere does not follow persistence or the expected playbook, and at least for the next week, the northern part of the Golden State is going to be hit hard with rain.  It may be called the Sodden State.

To give you some insight into this situation, below is the latest ensemble forecast from the highly skillful European Center modeling system fortotal precipitation over the western U.S. for the next 15 days.

Wow.  Not only is BC and Washington wet, but northern CA gets as much as 12-14 inches.  That would make a huge difference, helping to refill the reservoirs.


And the UW WRF model prediction of total precipitation for the next week is also wet with huge amounts over the Sierra Nevada and northern CA.


Not satisfied?  The 46 day precipitation anomaly forecast (the difference from normal) through December 3 shows a MUCH wetter than normal autumn over northern CA.


Now if they only would stop wasting water in agriculture (like 1 gallon used PER ALMOND), the water situation might stabilize down there.

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And I know you are curious about our big storm offshore.  It is still coming to our offshore waters on Thursday.  Here is the latest forecast from the European Center for Thursday morning.  Around a 955 hPa low.  Impressive

_____________________________________________

The Second Edition of My Northwest Weather Book is Now Available!

My new book is greatly improved and expanded over the first edition, with new chapters on the meteorology of Northwest wildfires and the weather of British Columbia.  A completely revamped chapter on the effects of global warming on our region.  And it has been brought up to date with recent weather events and the imagery is improved greatly.
 

Where can you get it?

Local bookstores, such as the University of Washington bookstore.  The UW Bookstore has just received several dozen copies.

Or secure a copy from the publisher:  UW Press.

Or Third Place Books in Lake Forest Park or Seattle.

And yes, there are online sellers like Amazon and Barnes and Noble.





The Bomb Cyclone Offshore

 The next 24 hours are going to be meteorologically exciting as a powerful storm grows rapidly offshore. And before I say more, let me make ...