Challenging Forecast

snapshotThe short term forecast is simple this evening.  Cold front plunges through tomorrow morning, then cold showers drop in behind.  This airmass is quite a bit more stable than previous post-frontal airmasses;  it’ll be tough to get heavy showers or thunderstorms.

Not much to talk about Saturday either, just cold with some brief sunshine, lots of higher clouds later.

Sunday through Tuesday is the real challenge.  Models (especially the GFS) have become more splitty and slower with the upper-trough to our west over the last 2 days.   Sunday we are on the southern edge of sloppy warm-frontal rain.  Light stuff and maybe some drizzle too.  Boring!  Monday the bulk of the rainfall may lift to the north.  Then Tuesday afternoon a secondary system develops well to the southwest and actually gives California a good dose of rain by Wednesday AM.  I see the 00z GFS now has NO rainfall over PDX from midday Sunday until Tuesday night!  That’s quite a change from 48 hours ago when it looked like a very wet period with even a possible windstorm setup Tuesday.

The split should “heal” a bit later next week.

Okay, I’m off for one day Friday.  So does that mean a surprise snowfall to relatively low elevations?  Could be.  Seems like each time Drew Jackson fills in for me we get some sort of weather event.

Chief Meteorologist Mark Nelsen

282 Responses to Challenging Forecast

  1. One thing is for sure, it looks like we are going to have several “threats” of strong winds thru Thursday…..

    47.8F….continuing light ESE winds

  2. ….but will it clear out Tuesday night to watch the Leonids??????…..

  3. Rob "Wrath" S.E. Portland says:

    Well I just watched Drew Jackson’s forecast.

    He says 15-20 G 40 likely with G 50 possible. I have to with respect say that this is a safe forecast. It is a bit conservative when you look at the WRF-GFS model, wind-cast model, and 0z cross section clearly show stronger winds. In my honest opinion I wonder if Drew may not taking in account the very strong winds just off the surface from 950-850mb and also isn’t factoring in the moderate-strong mixing to occur.

  4. Christiana--Forest Grove says:

    Drew’s forecast

    KPTV Forecast ** Watching the Wind **

    The National Weather Service has issued a High Wind Warning for the Oregon Coast through Tuesday morning. There is still a fair amount of uncertainty surrounding the details of a developing storm, but all indications are that winds at the beach could gust higher than 70 miles per hour. The highest winds are likely later Monday into Monday night, but it will be windy all day Monday into Tuesday morning.

    In the Portland area and throughout the Willamette Valley, it will also become windy later Monday, but the peak gusts will not be nearly as high as in coastal areas. Sustained winds inland are likely to be in the 15-25 mph range, with gusts to 40 mph possible later Monday evening. Off and on rain is also likely from Monday afternoon through Tuesday morning, with snow returning to the Cascades beginning Tuesday.

  5. Rob "Wrath" S.E. Portland says:

    00z WRF-GFS 4km view is nearly complete. Better detail and stronger winds.
    25-30kt sustained as early as 7-9 AM tomorrow

    Run the loop
    Larger area of 35kt sustained shown. Looks like fun.

  6. reposting the weather chat link in case folks didn’t see Larry’s first post. . . Friendly Chat

  7. Tyler says:

    Forecast winds reduced in Bellingham from 75 mph to 60 mph…but windy now, 47 mph

  8. Rob "Wrath" S.E. Portland says:

    Time for southerly gradient updates?
    I think so.

    Surface gradients
    As of 10 PM|Current|Hourly Change
    PDX-EUG: -2.0mb | 0.5mb Increase
    PDX-MFR: -5.2mb | 0.5mb Increase
    OLM-EUG: -5.7mb | 0.5mb Increase
    OLM-PDX: -3.7mb | No Change
    BLI-PDX: -9.0mb | 0.1mb Increase

  9. boydo3 says:

    BTW, I’m working in the central coast range tomorrow. Will report back if there is any fun stuff!

  10. Rob "Wrath" S.E. Portland says:

    Latest cross-section model

    50kt sustained just a few hundred feet off the surface

    The 4km view is running now which could be more/less impressive. I’ll post it when it is out.

  11. Jethro (Molalla) says:

    IMO 00z models didn’t show enough perpendicular gradient stacking in the valley to warrant gusts over 40-45 mph. The coast will see much higher for sure, of course.

    Guess I’ll wait and see what Mark has to say about it, or the 12z models, whichever come first.

    • Rob "Wrath" S.E. Portland says:

      Right gradient packing isn’t overly impressive, but the winds just off the surface are. It won’t take much mixing to surface those stronger winds and mixing is possible.

    • Jethro (Molalla) says:

      Good point. I forgot about that aspect.

    • boydo3 says:

      Yup, I’m going for a breezy event in the Valley but not a big deal. The coast from Tillamook north looks really windy. But since we haven’t seen much wind for a while I’m sure the TV crews will find a downed tree or two.

  12. Snow-Zone/Monmouth-Elv200' says:

    Hopefully Mark will chime in with his thoughts on the potential wind storm either later tonight or tomorrow morning for sure. I want 50-55mph G at least.

  13. Jacob PSE-BPA says:

    Puget Sound Energy prepares for windstorm
    crews have been put on standby and gear clean and ready to go A Wind Advisory is in place for the Sound.
    For SW Washington I Expect winds around 20-30 mph Gust no more then 40 at this time
    Andy Wappler will be going over maps tonight and in the morning

    Tetra Steve is God well weather God and you might want to be nice if you want snow this year

    PSE powers up its 149-turbines at wildhorse PSE is the second-largest utility owner and operator of wind check out the site its very impressive

    • Rob "Wrath" S.E. Portland says:

      20-30 G 40…. Very conservative. That could play out, but it is looking more likely gusts will be near/over 50mph.

      I want snow! So I respect Slayer Steve.

  14. maybe wind and more
    weather geeking meets grand fun
    nice karmic combo

  15. Tyler says:

    Long Beach has quite a list…

    Updated: 6:42 PM PST on November 15, 2009
    High Wind Warning in effect from midnight tonight to 10 am PST Tuesday…
    Coastal Flood Advisory in effect from 4 am Monday to noon PST Tuesday…
    High surf advisory in effect from 4 PM Monday to 10 am PST Tuesday…

    Looks like some more awesome wave photo opportunities! However, the winds appear much more dangerous this go around, trees and power lines probably coming down out there.

    • Rob "Wrath" S.E. Portland says:

      But…. you’re still going, right? lol

    • Tyler says:

      Nope…have to work! My parents are at the beach now, and I told them the earlier the better to make it home. Who knows when downed trees may close roads.

  16. Rob "Wrath" S.E. Portland says:

    Some additional thoughts of mine….

    I think deeper cyclogenesis is possible. Given the entrance jet of 160+kts and all of that cold air to be pulled into the dry slot/jet streak wrapping into each developing wave/low it seems realistic that lows could have excellent potential to deep well below what models are currently showing.

  17. Pimp Daddy says:

    Yeh, give Pierce a break! Dares a ho lotta weatha knowledge in dat man. WORD!!!!

  18. sds says:


    What’s got into you? Have you taken your meds today? You are not usually like this. SP has some rank on this blog and serious experience and you are calling him out?? Really??

    On an other line–has anyone paid attention to western wash. hydrology report for the next 24 hrs.–serious wind and rain–from 10 to 12 inches and gusts yo 70 knots on the coast.

  19. Rob "Wrath" S.E. Portland says:

    One thing we are discussing via weather e-mail list are that the 850-925mb winds are nearly identical in strength as we saw with the windstorm of December 2006. Assuming we can warm up nicely behind the warm front and can warm into the 58-62F range I am confident this will help mix down very strong winds locally.

    • Snow-Zone/Monmouth-Elv200' says:

      Yah, locally I wouldn’t be surprised if there are 60mph+ gusts in some interior locations if all goes to plan. Didn’t Salem reportedly gust to 80mph in the 2006 storm?

    • Rob "Wrath" S.E. Portland says:

      Yep S.E. Salem 80mph. Gusts east of I-205 were 55-70mph.

  20. Tyler says:

    Here is the forecast for Bellingham…even the NW interior will be very windy.

    Very windy. Rain likely. Highs in the 50s. South wind 30 to 40 mph with gusts to 60 mph.

    Monday Night
    Very windy. Rain. Lows in the 40s. South wind rising to 40 to 50 mph with gusts to near 75 mph after midnight.

  21. boydo3 says:

    Speaking of hot air, I think it might be time to dig out the brew kettle and mix up a nice fall ale. Will be looking for suggestions for next weekend’s alchemy.

  22. stilllearning says:

    Wow – I am having a hard time enjoying reading (and learning) from all of you when there is major disagreements going on. It’s weather – it is not predictable. From what I was able to read from everyone is we all want a great winter, but know that anything is possible. Can we please keep this blog educational and fun? I love reading all your posts and trying to learn from them – and I loved the light-hearted atmosphere of this blog (until today). Can’t we all agree to disagree (if that is what it takes) or at least understand that winter is unpredictable and we can all hope for snow???

    • Rob "Wrath" S.E. Portland says:

      <— Is currently hoping for snow. 🙂

    • boydo3 says:

      Weather, everybody talks about it but nobody does anything about. Except the Chinese. Get out those fighter kites for the next big blow!

  23. Not sure if I like the latest GFS 00z model…Showing a “double low” inside the main circulation….Would prefer one low center….Might keep the area windy for a prolonged period of time, however…..

    47.8°…light ESE winds

  24. Rob "Wrath" S.E. Portland says:

    It’s been a long time since I saw so many lows scheduled to slam into the area. Of course with this can come an even larger problem which would be a very deep low (sub 970mb) but double barrel structure. 00z WRF-GFS wind-cast model continues to show 30-35kt sustained winds for the Willamette Valley, so the winds haven’t changed a bit. As you watch the 00z WRF-GFS you see how each low moves around and each time the gradient packing tightens…. Trust me we are not out of the woods for 50+mph gusts in PDX.

  25. stevied (North Portland) says:

    Wow. WRF-GFS this evening shows more of a wind event than the MM5-NAM. Shows 35kt winds in the valley and 50+ at the coast. If you favored the WRF-GFS over the MM5-NAM, which I usually do, there’s still a shot at 50-55mph gusts in the valley and maybe around PDX and some 70-90mph gusts at the coast. It shows a 979mb low hitting Central/southern Vancouver Island

    • Rob "Wrath" S.E. Portland says:

      Yep and if any of those lows were to dumbbell around the other it would cause the southern low to abruptly swing eastward and that could put a tight gradient packing right over our area. It’s going to be fun to watch how things ultimately transpire.

  26. Even if it’s not a full fledged wind storm, I love a good, blustery NW Fall day no matter what. Sounds like this week will be fruitful in that regard, especially with another strong front later this week (NWS mentioned the Thursday possibility for more wind in their earlier discussion, I think)…

  27. Jethro (Molalla) says:

    NCEP-GFS showing same thing, stevied…

    Even if it doesn’t bring a high wind warning, it should at least bring a little fun weather in the form of windy, rainy conditions Monday night and Tuesday morning.

  28. Timmy_Supercell (Hillsboro) says:

    Again, what was in Steve’s posts was never a theory, its clearly a cycle that already happened, and using that info to discuss the “possibilities” for this winter. He never said anything was for 1000% going to happen.

  29. stevied (North Portland) says:

    Well, the 00z MM5-NAM doesn’t seem to show anything real significant in Portland for Monday/Tuesday wind event. Shows a 984mb low and maybe 35mph gusts around Portland with 50-60mph gusts at the coast.

    00z NAM shows something new for Thursday morning… maybe another wind possibility for then.

    We’ll see. Should be a good weather-watching/monitoring week!

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