Hurricane Oho's Future Remnants Could Bring Gusty Winds, Heavy Rain to Pacific Northwest, British Columbia, Alaska
Hurricane Oho is racing north-northeast through the central Pacific and its future as a post-tropical remnant into British Columbia and southeast Alaska is arguably its most interesting aspect.
Despite this, Oho will eventually lose its tropical characteristics by later Thursday, owing to increased wind shear and cooler water as it moves north-northeast.
Current Information/Satellite
Now let's dive into the details Oho may have an influence in the higher latitudes.
Oho To Bring Strong Winds, Heavy Rain?
Oho is forecast to move north-northeast the next couple of days, transitioning into a non-tropical area of low pressure sometime Thursday at roughly the same latitude as Northern California.
Oho Projected Path
Oho is forecast to be a non-tropical area of low pressure at the end of this projected path graphic.
The remnant of Oho will then get pulled north-northeastward by a large upper-level trough in the Gulf of Alaska. This will help pull a deep plume of moisture associated with Oho into western Canada, southeast Alaska and possibly parts of the Pacific Northwest.
The majority of the computer model guidance actually strengthens the post-tropical "ghost" of Oho as it nears the western British Columbia/southeast Alaska coasts Friday. That could bring some high winds to those areas, somewhat analagous to a strong early or late-winter Pacific storm.
The National Weather Service (NWS) out of Juneau, Alaska mentioned in a Wednesday evening discussion that the system could bring a period of hurricane-force (74 mph or greater) winds to the east of its track
That has prompted high wind watches to be issued for portions of southeastern Alaska, as wind gusts over 60 mph are certainly possible.
Forecast Waves and Winds
A look at forecast wave heights and wind speeds across the region.
Weather Pattern
This graphic shows the upper-level weather pattern that will pull Oho's remnants towards the Northwest and western Canada.
The computer models also agree that the majority of the moisture associated with Oho will go into western British Columbia, Canada, as well as southeastern Alaska.
Widespread three-inch-plus rain totals can be expected in these areas, not only from Oho's remnant, but from the overall stormy pattern described earlier over the Gulf of Alaska and northeast Pacific Ocean.
While the buildup of mountain snowpack is crucial this and every season for water supply in the West, parts of the drought-stricken Pacific Northwest should relish in some soaking rain from this system Friday into the weekend.
Model Rainfall Forecast Through Saturday Night
Locally heavier amounts may occur. Not all of the rainfall shown on this map will be from Oho's post-tropical remnant.
For now, it appears this rejuvenated post-tropical Oho will track far enough west and north to avoid bringing any significant wind to the Pacific Northwest.
A couple of frontal systems may follow behind Oho's remnants this weekend into early next week, keeping the unsettled weather conditions in place across the Northwest and western Canada.
Where No Hurricane Has Gone Before?
On its current path, Oho is taking a peculiar track to the northeast. Although tropical systems do, on occasion, move to the northeast in the central Pacific, since 1949, no late season (October or later) system has formed south of Hawaii and moved to the northeast.
Rare Hurricane Track
A graphic showing the northernmost hurricanes in the central and eastern Pacific, dating back to 1949.
Furthermore, no hurricanes have ventured into the region off Northwest Coast of the U.S., extending west several hundred miles. Although prior to the period of record, a weakening hurricane did strike southern California as a strong tropical storm in 1939.
Ocean temperatures cool rapidly with northward extent in the Pacific, the main mitigating factor when it comes to tropical systems maintaining intensity in the region. However, given the persistent El Nino pattern, such water temperatures have been running anomalously warm this tropical season.
It's fairly uncommon to see a storm in the central Pacific basin take this type of path, making it an interesting case from a meteorological perspective. On average the central Pacific basin sees far fewer named storms (4-5) in a given season compared to the northwest Pacific (26), lessening the opportunities for this to occur with central Pacific systems.
At times, the Alaska, western Canada and the Pacific Northwest can see impacts from the remnants of western Pacific typhoons that recurve into the north Pacific while transitioning into a non-tropical low-pressure system. An extreme example of that happening is the Columbus Day storm of 1962, which contained the remnants of Typhoon Freda.
Eric Blake from the National Hurricane Center also noticed something peculiar about Oho's track.
In most hurricane seasons, you may see a named storm move westward across 140 degrees West longitude, after which the Central Pacific Hurricane Center takes over issuance of advisories on the system from the National Hurricane Center in Miami.
With Oho, the reverse may happen if it is still a tropical cyclone by the time it crosses 140 degrees West longitude. It would become an eastern Pacific tropical cyclone, with advisories -- albeit perhaps only 1 or 2 as a tropical cyclone -- issued by the NHC in Miami.
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