Typhoon Songda’s Leftovers: Stormy PacNW Ahead!

11am Monday…

In the fall it is not unusual for tropical cyclones (referred to as typhoons) in the western Pacific to get caught up in the jet stream as they die.  Then the leftovers end up somewhere along the west coast of the USA.  They don’t survive the move over cold water, but their remains can help new storms develop much farther east.  They more or less transfer heat & moisture from the tropics into the mid-latitudes…where we live.  That’s going to happen later this week and it’s part of the reason Thursday through early next week is looking like the stormiest mid-October period we’ve seen in almost a decade.  I recall a strong storm in mid-October 2007, but none since that time.  October typically has quite benign weather until the last week when rainy weather kicks in. This year that rainy season has started early!

The Next 3 Days

They look great!  We have leftover areas of fog & low clouds today, but sunshine will gradually break out.  Tuesday looks incredible with bright sunshine and cloudless skies under a dry easterly wind.  This should be a great photo-op day with the blue, sun, & changing fall leaves.

Thursday through Early Next Week

A mid-winter strength Pacific jet stream sets up over the entire north Pacific ocean.  Check out one model forecast of wind speeds up at jet-cruising altitude:

jetstream_sat

jetstream_wide

That would be quite a tailwind flying from Japan to Portland if one followed the jet!

Note that as the strong jet arrives on the West Coast, it makes a slight curve to the left.   It’s a long story, but there is lots of lifting high up in the atmosphere in that spot (called the “left-exit region”) in the jet.  Powerful surface low pressure systems can spin-up in that spot and Thursday through Sunday it is quite close to our coastline.  This is the pattern than CAN produce big windstorms for us.

The gold standard of models, the ECMWF on last night’s run showed 3 deep lows that come relatively close to the West Coast.  Thursday night, Saturday morning/midday, & Monday.  All three will produce a round of wind and rain for our region.  This isn’t really an atmospheric river setup, but a series of separate storms that are all warm and very wet.  Regardless, it’s going to be mid-winter type wet.  Take a look at the ECMWF rain forecast for Salem:

ecmwf_ensemble_rain_sle

The bottom shows accumulation of rain from the operational model in blue…somewhere between 5-6″ by Monday afternoon!  The group of 51 ensembles averaged together are just under 5″.  The colored lines above each represent one of the 51 ensemble members.  Excellent agreement with very wet weather…a soaker!  Note it tapers off dramatically after Monday/Tuesday next week.  I mentioned in the 12 Day Trend last night at 10pm that the weather turns more reasonable after about 6 days of this crazy stuff.

The morning GFS shows the soaking as well, but for now not as extreme.

gfs_7day_precip

Looks like around 3″ in most of the valley.  You can ignore the bullseye over Portland, the model is pushing the south Cascades rain in Washington out over the lowlands.  That doesn’t happen.  Even with this “lighter” 3″ of rain, that’s more than we typically get in an entire October!

As for wind, lots more uncertainty on where the strongest wind is headed  as Typhoon Songda as it dies east of Japan and follows the jet stream.  If you are thinking this is similar to the Columbus Day Storm…it is somewhat, although the track was farther south in 1962.

gefs_wp23_2016101006

Songda’s remains turn into a deep low pressure center that ends up somewhere between Vancouver Island and Haida Gwaii according to both the GFS and GEM models this morning.  The overnight ECMWF was farther south with a 968mb low into central Vancouver Island.

ecmwf_satmidday

That’s a big windstorm for the coastline but too far north and west for a windstorm in the valleys.  It’s interesting to note that 6 out of 51 ensemble members have some sort of devastatingly deep low pressure center much closer to us for a big windstorm inland.  Yes, I counted…but that also means 45 out of 51 did not.  There was even one member that had a 945mb low center hitting Vancouver Island.

So we’ll keep a close on it all week as we get closer to see exactly where the deep low pressure systems are going to spin-up.  Otherwise enjoy these 3 dry days because we have a huge soaking ahead!

Chief Meteorologist Mark Nelsen

28 Responses to Typhoon Songda’s Leftovers: Stormy PacNW Ahead!

  1. W7ENK says:

    High Wind Watch upgraded just now:

    HIGH WIND WARNING
    NATIONAL WEATHER SERVICE PORTLAND OR
    936 AM PDT WED OCT 12 2016

    https://inws.ncep.noaa.gov/a/a.php?i=6675061

  2. 18z NWS/NCEP Pacific Surface Analysis
    Typhoon Songda has now explosively intensified into a Super Typhoon. This was not forecast and in fact the JMA yesterday only had this reaching Cat 3 before weakening to eventually a Tropical Storm as it is fully ingested by the westerly jet. Pretty amazing it just continues to strengthen even though it is under a strongly sheared environment. I have never seen a fully intact super typhoon being pulled into our westerly jet before. Remnants of or degradation down to a Tropical Storm perhaps, but never a super typhoon and as we speak Songda is accelerating northeastward. I would think this suggest more energy, more latent heat, more explosive cyclogenesis potential…. but where does it make landfall? That is the $32 dollar question

  3. High Desert Mat says:

    Jesse, you’re not onthe forums anymore. Where are you? Mark and I are curious.

    Oh welcome back Atmospheric Wrath.

  4. W7ENK says:

    Cold night last night. it was down to 44° when I went to bed, so I brought my pepper plants inside, set them in the kitchen. It fogged up a bit overnight, which bumped the temperature up to 51° this morning. Today is shaping up to be a glorious, blue sky sunshine-y day! 70 degrees, maybe? That’s probably too much to ask for, but I’ll take the sunshine any day.

    Windstorm in the works, eh? That should be fun, especially after a couple good soaking rains…

  5. 36.8F at present here. That’s my lowest temperature since March. But it’s under clear skies. Looking at the forecast for the next few days, I won’t see it that low again for a while.(well, excluding possibly tomorrow morning).

  6. runrain says:

    NWS says poss gusts to 55 on Saturday. Way too early for much confidence but great to have the possibility!

  7. Paul D says:

    So now the 7-day forecast shows dry on Thursday – really?!?

  8. Hey, been awhile
    No big deal, but tonight’s 00z ECMWF at day 5(HR 120) places an insanely deep and dangerous 957mb low into Tatoosh Island. Very big difference compared to previous runs as the remnants of what is currently Cat 3 Typhoon Songda develops much further south around 40 N and nears that critical 130 W, 40 N. More model craziness on the way as they resolve the abnormal amount of tropical moisture and energy.

  9. Are fall typhoon leftovers the main reason why PNW rainy season begins abruptly, peaks early, and then gradually tapers out over several months in the spring?

  10. I’ve seen some of my heaviest rainfalls of the year around mid-October. Back in October 2003 on the 16-17th, I saw my heaviest 2 day rain amount ever with 6.83 inches. I don’t expect anything quite that much this time, but about half of it might be possible.

  11. JJ78259 says:

    Runrain is getting his wish!!

    • runrain says:

      Yippee!! Now, if we can just get Rob to pop back in when the storms start forming. He has such great analysis. I’m ready for one of those bomb-o-genesis storms!!

  12. Nathan Place says:

    What are the chances any of this wind makes it tho Portland?

  13. yspofor@comcast.net says:

    Mark, what about potential Winter snow????

    • I don’t know how many times this has been answered since September. At this point in the season even attempting to forecast potential winter snow, is anybody’s guess. Which is probably why Mark hasn’t made an “official” snow post yet.

    • Josh "The Snowman" from Gladstone, OR says:

      Mark only hints within 7 days and gives it a percentage inside of 3-4 days , from what I have seen from that chicken :).

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