Another Hurricane Abruptly Turns Into Monster. And Will Nor'easter Result

Satellite image of what was Category 5 Hurricane Willa off
the western Mexican coast on Monday. 

Following a dangerous and increasing trend in recent years, Hurricane Willa blew up into a monster off the west coast of Mexico between Sunday and Monday.

It's going to come ashore today in southwestern Mexico, and I imagine we're going to hear a lot of news about destruction in that neck of the woods in the next few days. It'll come ashore north of Puerto Vallarta.

Willa went from a humdrum tropical storm to a Category 5 monster in just two days. That's incredibly rapid intensification.  Waters off the Mexican coast are running one to two degrees warmer than normal, and that certainly helped with the intensification.

That type of explosive development seems to be a trend in tropical systems.

Willa might be an indication that rapidly intensifying hurricanes will likely become more common with global warming. There won't necessarily be more hurricanes than there used to be, but a greater proportion of them will intensify really quickly.

There's more research on this trend. A 2016 paper from MIT examined this.

Reports the Category 6 weather and climate blog:

"MIT hurricane scientist Kerry Emanuel explained that not only will global warming make the strongest hurricanes stronger, it will also increase how fast they intensify."

That's especially dangerous when the intensification comes just as the hurricane is getting ready to make landfall. We saw that with Hurricane Harvey in Texas last year and Hurricane Michael earlier this month in the Florida Panhandle.

Emanuel's argument makes sense. If the overall atmospheric conditions are favorable for a hurricane, warmer water will more efficiently feed the hurricane, making it intensify more quickly. Warmer ocean water is widely expected to be around as climate change continues to take hold.

When a hurricane intensifies greatly just before coming ashore, these monsters would catch people in the storm zone off guard. They might be expected a so-so storm and instead getting something more powerful. That happened with Michael this month on the Florida Panhandle.

According to the Category 6 weather and climate blog:

"The analysis found that the odds of a hurricane intensifying by 70 mph or greater in the 24 hours just before landfall were about once every 100 years in the climate of the late 20th century. But in the climate of the year 2100, these odds increased to once every five to ten years."

That might sound like a whole lot. But as we saw with Hurricane Michael, this type of intensification is beyond catastrophic.

In the case of Willa, the explosive intensification occured when the storm was a fair distance offshore. It looks like it peaked yesterday with top winds of 160 mph. As is typical with hurricanes, Willa has rearranged the thunderstorms around the eye of the storm. This tends to weaken the top winds, but spreads strong, dangerous winds over a wider area, and can make the storm surge worse.

Willa was down to 130 mph this morning, and wind speed will probably drop a little more before landfall. But it will still be a serious, life-threatening hurricane.

The remnants of Willa will cross through Mexico and into southern Texas, spreading more unwelcome rain in an area of the Lone Star State that has had far too much rain and flooding lately.

The ghost of Willa will then run eastward across the Gulf Coast and become an ingredient to the formation of what looks like the season's first nor'easter.  It will make a run up the East Coast over the weekend.

It's too soon to determine what exactly that nor'easter will do, but it could have implications here in Vermont later Saturday and especiallly Sunday.   We have a good chance of a cold rain, maybe some wind, and maybe some snow in the higher elevations. We don't yet how far to the east the storm will go, so we don't know how heavy the precipitation might be.

We'll know more by about Thursday.

This nor'easter will come just about on the anniversary of last October's nor'easter, which brought one of the worst and destructive windstorms on record to parts of Vermont. We're quite sure whatever this weekend's nor'easter does, it won't be as bad as last year's.