Tropical Storms Invade Hawaiian Waters: The Role of El Nino

Normally, tropical storms and hurricanes avoid the area of the Hawaiian Islands.  

Why?   Because the nearby Pacific is usually too cool!  

In general, surface temperatures must reach at least 80°F (26.5°C) to sustain tropical storm development.

This year, due to a very strong El Nino, temperatures south and east of Hawaii are 1-2 C above normal (see map of differences from normal for sea surface temperature)

As shown by a more detailed, close-in map, the 27C line just reaches Hawaii.    A "warm enough" bath is open.

No wonder tropical storms can approach Hawaii this year!

The effects of the warm water have been dramatic.

Consider satellite imagery from yesterday afternoon...and be prepared to be impressed!

A high-resolution satellite image shows three hurricanes/tropical storms over the eastern Pacific, with a red arrow pointing to the Big Island.  Wow.

Here is an infrared image of the storms.   Amazing.

Even more amazing is a series of forecast maps of evolution of the tropical storms.  I will show you maps of atmospheric moisture through depth.

Today at 11 AM, the swirls of moisture around three tropical storms are evident.  Stunning.

On Saturday morning, they are still there, with one storm passing south of the Hawaiian island

On Sunday morning, the western storm starts moving northeastward towards Hawaii!  Some moisture from the eastern storm extends into southern California, which is going to get some rain as a result

Now the most amazing thing.   The two eastward storms start to interact on Monday.

Then the combined system starts to move northwest on Tuesday.

The storm's crazy movement near Hawaii is reflected in the total precipitation over the next 10 days. You can see the northward jog, followed by a turn to the east.     Quite unusual!

A great time to visit Kauai if you are meteorologically inclined. 😊

The Fall Transition Has Begun

 One of the most remarkable aspects of Northwest climate is the rapid fall transition from summerlike conditions to cold and wet between September 1 and November 1.

This is illustrated by the average temperatures at Seattle (below).  

The current temperature forecasts are close to climatology, with no more 90s or 80s.

Climatological precipitation is on a very steep incline up (probability of measurable precipitation is shown below).  By November 1, we are about as wet as we get.

A wet weather system is now right off our coast and will move in tonight and tomorrow (see infrared satellite image for this evening).  Does not look like a summer pattern!

Rain totals through Thursday morning (shown below) will be significant.  Importantly,  precipitation will extend over eastern Washington, where some fires are still smoldering.

The official NOAA 6-10 day forecasts are for cooler-than-normal and wetter-than-normal conditions over the West Coast:

The timing of this cool/wet weather is perfect to facilitate an early end to the serious wildfire season.