Tuesday AM Update
Ignacio is here! At least its transformed, non-tropical form is now moving into British Columbia. (see image) We will only get some clouds and sprinkles.
Many of the Northwest's most intense and memorable storms had their origins as tropical storms. For example, the October 12, 1962 Columbus Day Storm began as Typhoon Frieda in the western Pacific before if evolved into a hugely powerful midlatitude storm (see map). There have been plenty of others.
So it is with some interest for meteorologists that a potent hurricane, Ignacio, approached Hawaii and then swung northward towards the Aleutians, being steered by a huge area of high pressure over the Pacific.
First, let me note that I have never seen so many tropical storms in the eastern Pacific as we've had the last few weeks. Here are satellite images for August 30th---there are three category 4 hurricanes storms and one tropical disturbance...amazing. This is a record according to the National Hurricane Center. As an aside, since I know this is going to stimulate the "new normal" crowd, I should note that the storms are probably the result of the very warm temperatures in place due to the strong El Nino that has developed.
Ignacio is east of Hawaii in these pics.
Let's follow a sequence of the satellite images. On Wednesday at 11 AM, the storm was north of Hawaii
And 11 PM on Friday, it was N-NW of Hawaii and evolving into a midlatitude storm, with a far less symmetric cloud shield. But storms, like people, don't forget where they came from, and often such transitioning storms retain some of the strong inner circulation of their tropical roots.
The upper level (500 hPa, roughly 18,000 ft) map for 11 PM on Friday shows the big high in the eastern Pacific that is steering the remnants of Ignacio. Ignacio is indicated by the closely packed circular lines north of Hawaii.
So will Ignacio circle around the high and slam into the Northwest? Will the ridge of high pressure weaken it?
Let's find out what the weather forecast models are saying! Here is the latest 12-h forecast from UW WRF for 5 AM Sunday showing 3-h precipitation and sea level pressure. Ignacio is clearly seen, with fairly deep low pressure (lots of lines) and heavy precipitation near its core. The big eastern Pacific high pressure is also quite evident.
By 8 PM Monday it is has rounded the NW part of the high and is heading for us! Still plenty of juice.
Tuesday at 2 PM, it reaches the central BC coast, but has weakened considerably.
And by 5 AM Wed. Ignacio has been impaled on the BC coastal mountains and dying through the encounter. Perhaps we will get a bit of cloudiness from it, here in Washington State. Not much more.
So it appears that Northwest weather lovers looking for storm action may be disappointed, with the remains of Ignacio moving into British Columbia. But it is all so amazing: a storm forming in the tropics off of southern Mexico takes a huge loop around Pacific, skirting Hawaii, practically reaching the Aleutians before it turns back to North America to hit western Canada.
Literally, what goes around, comes around.