Nightmare Forecasting

A casual viewer may have noticed the 7 Day forecasts on local TV web sites (and on the air of course) are all over the place the last 3 days.  Combine that with changing numbers just on our 7 Day forecast and a person could easily conclude that we are just throwing darts at a wall.  They wouldn’t be too far off tonight. 

The forecast is a real pain the next 7 days.  The problem?  An upper level trough, a disturbance in the upper-atmosphere, moves down from Canada to just off Oregon by Wednesday.  Then it backs off a bit, links up with another trough moving across the Pacific, and swings some moisture our way at times through early next week.  The issue is that each model and even runs within models themselves each disagree on where the low is at any one time.  If it’s closer to us we get cooler/showery weather.  If it backs off just a bit, much warmer air surges north ahead of it and we can get quite warm.  24 hours ago models were indicating we could hit 80 degrees next weekend as the low moved well off the coastline.  That’s now gone…we’ll see if it reappears.  As forecasters we can’t just follow each model run in patterns like this.  If we did, our 7 Day forecast would have gone from a high of 80-82 next Sunday to 60 just 24 hours later (a good example!).  So we have to make an educated guess (yes, I said that) based on experience and trends in models.  And we also have to avoid what many of you here are familiar with:  Model Riding.  That’s when your forecast and thoughts change with each model run.  Since many models now come out 4 times a day (all arrive at least twice a day), this can give you whiplash from the amount of weather information flying around.

To make it worse…if it was October-February our viewers wouldn’t necessarily care much…really, a 40 degree rainy day or a cloudy 50 degree day?  Most of us stay inside anyway.  But from later March through the summer the public (me too!) has much higher expectations and wants to get outside.  So any forecast of several days of sunshine and warm temperatures is followed closely.  The viewer REALLY wants that to happen…and extreme disappointment is the result if/when we have to put showers/cool weather back into the forecast.  That would include nasty emails and sometimes rough voicemails too.  So some Springs we get through this with just nice fronts and then ridges of high pressure that give us some sunny weather.  Others are dominated by these annoying lows. 

Chief Meteorologist Mark Nelsen

129 Responses to Nightmare Forecasting

  1. Aloha 185 says:

    In the sink

  2. Timmy_Supercell (Hillsboro) says:

    Things are starting to look broken up. Not saying there is no chance for lightning in PDX, but storms are not at all that strong anymore. Medford radar is also no longer impressive.

  3. Jethro (Molalla) says:

    Getting pretty dark out this way… I’ll move the garbage can to the curb to increase our chances of something ‘severe’ developing. 😉

  4. Timmy_Supercell (Hillsboro) says:

    Where is everybody?

  5. Jesse-Orchards says:

    Looks like things are starting to pop over the Cascades in SSE flow aloft. Some cells have already developed as far north as Clackamas County.

  6. Timmy_Supercell (Hillsboro) says:

    Alright, things are really starting to cook…

    Here is this one impressive looking thunderstorm SW of Diamond Lake with a 59.5 dBZ peak:

  7. Timmy_Supercell (Hillsboro) says:

    Somethings trying to brew in the Valley.

  8. pedro771-tigard says:

    There are some storms in the area of SW Oregon now.I doubt any go over Ashland though.

  9. Tyler in Hazel Dell says:

    It was rather frosty this morning, and now there are showers/storm developing over the Cascades. Sure would be nice to see frost and thunder all in the same day!

    http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?rtx_n0r+/2h/

  10. Timmy_Supercell (Hillsboro) says:

    Good looking thunderstorm developing SE of Eagle Point. http://i39.tinypic.com/wu54j6.jpg

  11. Mr Data says:

    2/3 pieces of the Triforce.

  12. Mr Data says:

    Do you think we will upgrade to the Triforce of Wisdom today with our T-storm threat instead of just boring old Courage?

    I think I’ll have another listen to Fox 12 WeatherBlog radio by Mark Neslon and his Assistant Timmy Supercell:

  13. Timmy_Supercell (Hillsboro) says:

    Something sure is developing in southern OR.

  14. PaulO says:

    Coming back over the Fremont Br. from lunch I see lots of mini cumulus build-ups beginning to the south-southeast and looking at the radar it appears development is beginning in southern Oregon. Warming rapidly outside also. I think we have a fair chance of some thunder later and a darn good chance of some showers by evening.

    • Timmy_Supercell (Hillsboro) says:

      Where is this located?

    • PaulO says:

      Portland. Check out Medford radar and you can see lots of small devlopment beginning. All streaming west of north too. Some even as far north as east of Eugene. No lightning yet that I noticed but it is early. Satelite shows the low shifting north also. PDX has went up 4 degree/hr since 8am and was 57 at 1pm. Much of the city is near 60 or above already. For a not so perfect storm set-up I like the way it is coming together so far is all.

    • Timmy_Supercell (Hillsboro) says:

      I like it too Paul. Before I looked at Medford radar I wasn’t so sure about this. But the way the radar shows all of those individual cells developing rapidly, looks good to me.

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

    Convective temp is 60-61F. As of yet no instability has developed north of Mt. Jefferson. MUCAPE 100J/kg south of there.

    Monitor all Upper Air and Thermodynamic Fields (plus much, much more) with the new SPC Mesoscale Analysis page.
    http://w1.spc.woc.noaa.gov/exper/mesoanalysis/new/viewsector.php?sector=11

  16. Battle Ground Brian says:

    Low 31.5

    Currently 62 @ 1pm.. Some spots in clark county will approach a 40 degree diurnal change by the end of today.

  17. Timmy_Supercell (Hillsboro) says:

    SPC convective outlooks actually doesn’t even mention us now:

    http://www.spc.noaa.gov/products/outlook/day1otlk.html

    • Rob "Wrath" S.E. Portland says:

      It didn’t earlier either, Timmy, but as I pointed out they did shift things northward.

    • Rob "Wrath" S.E. Portland says:

      58.1 … Should make the 62-66F range even with filtered sunshine.

    • Timmy_Supercell (Hillsboro) says:

      Its good we are warming up. Hillsboro is I guess still colder than most people at this time of year.

    • Timmy_Supercell (Hillsboro) says:

      Nevermind, Hillsboro just updated 30 seconds ago…. 57.9F

      😉

  18. Timmy_Supercell (Hillsboro) says:

    Looks clear to my west, but south/east locations need to clear for things to pan out

  19. Timmy_Supercell (Hillsboro) says:

    (plays distorted thunder sound on the Fox 12 Weatherblog Radio)

  20. Timmy_Supercell (Hillsboro) says:

    I feel as if dynamics for thunderstorms are incomplete. Sort of like 1/3 pieces of the Triforce.

  21. k5mitch says:

    60.1 here in NE PDX

  22. Mr Data says:

    53F stilll: *Pulls out the T-storm cancelled card*

    • Timmy_Supercell (Hillsboro) says:

      All because of these high clouds, if they hang around the next hour or so we may not have enough heating…

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