Best Chance For Snow Yet!

January 25, 2008

Sure looks good for snow coming up the next few days, even down to the lowest elevations.  First, let’s talk about tomorrow though.
A nice clear night, at least through the next few hours, gives the entire region another freeze.  Then clouds move in around daybreak.  Models continue to produce moisture out of the cloud cover sometime during the 7-10am period.  We all know the cold air at the surface sure isn’t going to suddenly be swept out by a south wind, so most likely whatever falls before noon will be some sort of frozen precipitation.  As of the 4pm Salem sounding, we would see snow.  But I have no reason to doubt the strong warming shown overnight between 1,000-4,000′ on models.  So snow looks unlikely.  Far more likely is a spotty/messy mix of freezing rain or sleet (ice pellets).  I’ll talk more about that wintry mix around 10:45pm tonight.  I expect the combination of low level southerly flow, cloud cover, very light precip, and a nearly dead east wind by 10am to push temps into the 34-38 degree range through the early afternoon.

Then a strong cold front sweeps in from the northwest in the evening Saturday.  This will be the leading edge of arctic air that has poured out of SE Alaska out over the Pacific.    Our RPM model, and to a lesser extent the MM5-GFS, show the cold front enhancing and stalling over NW Oregon late Saturday night and Sunday morning.  I notice wind on both models is calm at the same time the steady precipitation is falling.  That’s why I went with a trace to 1" even in the city at that time.  There appears to be a break behind the front Sunday morning through early afternoon before the really cold showers surge inland in the evening.  (A brief break…I can’t believe I just saw a forecast for snow on another station right now with temps in the 40’s overhead!).  Okay, moving on…so then the coldest atmosphere moves over us later Sunday night and Monday morning.  Plenty of moisture too.  This is one of those situations where a heavy line of showers could dump 2-3" in one hour on one side of town, but nothing 10 miles away…That’s why I think forecasting a specific snow level (like 200 or 300′) is total crap in a pattern like this…just being honest!  Location and precipitation intensity will be far more important.

Next bit of excitement will be Monday night and Tuesday.  Depending on where the surface low tracks with that system, we either get rain with a 2,000′ snow level or a snowstorm down here in the city.  Too early to tell.  Enjoy the weekend.  I’ll be in Sunday evening and post again then…Mark Nelsen

Tornado Map

January 11, 2008

Vuotornadodamage10jan2008fin_8Well, after numerous tries (about 15 minutes), I finally figured out how to get this thing into my blog.  This "thing" is a great map created by two guys…Wolf Read and Steve Pierce.  They started with Google maps and laid on the track of yesterday’s tornado.  Then Steve, with plenty of time apparently, has put in colored dots for the different levels of damage seen along the track.  That’s a lot of work and I really want to thank them for that.  So sit down this weekend, get your favorite beverage, and take a much closer look.  Get the large image here: Download VUO_Tornado_Track.jpg

I’ve mentioned this before, but you could drink MANY beverages while checking out Wolf Read’s Storm King Website .  This is pretty much the Wikipedia of Northwest USA Windstorms.  An incredible amount of work & research has gone into that site.  Steve Pierce has been watching (and forecasting in spare time) Northwest weather for at least 20 years.  He REGULARLY sends emails out to local media and meteorologists about significant weather events that may be on the horizon.  I used to worry that he could be a stalker or a bit "off", but now that I’ve met him a few times over the last few years, I think he’s a great guy that inhales & exhales pretty much only weather.  Plus, he doesn’t jam up my email inbox as much anymore.

Let’s talk weather briefly.  It’s pretty slow this weekend.  A weak system moves onshore tonight, giving us rain later.  Post-frontal showers continue through midday Saturday, then ridging takes over through Sunday night.  I notice we don’t get much (or any) offshore flow Sunday.  That screams FOG! after all the weeks of rainfall and clearing skies Saturday evening.  So even though it’ll be dry Sunday, I don’t think we’ll get that much sunshine.

A bit more interesting Monday as a very strong cold front sweeps in from the northwest.  We go from about  43 degrees early Monday at 4,000′ to about 22 degrees Monday night at the same elevation.  A quick wind switch to northwest brings in much colder air Monday evening.  The 00z NAM is quite a bit colder than the 00z GFS or MM5 models.  It would imply some snow in the hills before we suddenly dry out after dark.  Something to keep a close eye on at least.  Definitely worthy of a hidden snowflake in the 7 Day forecast.  Tuesday-Saturday’s forecast (Days 4-8) is quite simple.  Ridging overhead, but not a whole lot of offshore flow.  So seasonably cool, but no blast of cold air from Canada, and no strong easterlies through the Gorge.  IF the upper level ridge were to set up closer to the Coastline, we’d get strong high pressure at the surface to our east and gusty Gorge wind. IF the upper level ridge were farther offshore, then much colder northerly flow would set up over us.  Neither is in the cards right now.

Beyond Day 8 (MLK Weekend), models are ALL over the place.  ECMWF implies cold air just to our north that never gets here, mainly dumping out over the ocean.  GFS changes with each run.  Any guesses?  I’m looking forward to a break in the weather next week.  Time to catch up on emails and other "office tasks".   Mark Nelsen

What a Day!

January 10, 2008

SnapshotConsidering it was going to be a quiet post-frontal shower day…I sure spent a lot of time on TV.  We were live from 12:45pm to 5:05 pm, then of course the 90 minutes from 10-11:30 pm.  I think all my deep thoughts and creative energies have been sucked out right now, so a very brief post.
The strongest tornado in the immediate metro area since 1972 hit N. Vancouver this afternoon.  The NWS team sure did a quick job with the post-storm survey.  They say EF1 for a rating.  That means peak gusts maybe up to or a bit over 100 mph.  Not unlike the December Coastal wind event on the North Coast.  Damage is similar too.  Lots of trees blown down, broken off, and roofs ripped up.
Much calmer weather coming up over the next 7-9 days.  Models can’t quite agree on what to do late next week.  But at least until Friday the 18th, they all agree on dry, but chilly weather.  The 00z GFS still indicates arctic air surging south over the MLK weekend.  But the 12z ECMWF dumped the cold air out over the ocean instead.  We’ll have many days to talk about it, so I’ll take a closer look tomorrow…Mark Nelsen


January 10, 2008

This is late coming… but we’ve been busy.  I’m sure you can understand…

More information coming later, but for now — chat away about this historic storm.

-Drew J.

New 4pm Show

January 9, 2008

SnapshotSnapshot2We just found out, officially, that FOX-12 will begin a one hour newscast from 4pm-5pm weekdays.  This will begin on March 3rd.  So we’ll join the other stations in having an early (very early) evening newscast.  We’ll also be adding a 5pm Saturday show.  That means the First, Live, Local weather team will be on the air every evening of the week, as well as late night and morning shows too.

On to some brief weather talk.  I’m a little bit bored with our current weather pattern (rain, wind, mountain snow), so it’s nice to see a break and change in the weather regime on the way.  A ridge is going to build over the West Coast, or offshore aways, depending on which model you look at.  It begins Sunday, then a system comes over the top of the ridge Monday-early Tuesday.  It quickly rebounds and the rest of next week may be dry.  2 things to note.  The ECMWF has been much more consistent with the ridging placement, so that’s why I put a few snowflakes into Monday night’s forecast.  It’s a much sharper shortwave diving through the Northwest at that time with a colder airmass than what’s shown on the 00z GFS.  It still isn’t a real good snow setup for PDX because the moisture usually ends quickly with a fast-moving wave like the one forecast to move through.

Most likely what grabs your attention is the slight retrogression of the ridge later next week.   The ECMWF shows it a bit, and the GEM  has the same idea.  But the 00z GFS really went nuts this evening.  It has an arctic front moving through the Northwest next Friday with snow, then bitterly cold arctic air behind it for the MLK weekend.  It’s 9 days away and it IS the GFS, so I assume future model runs will change dramatically.  But fun to watch closely anyway.  The "Mark Nelsen Effect" could be showing up on the models…I have 3 different days scheduled off clustered around the MLK weekend.

Looks like Mt. Hood Skibowl has more snow at this point in the year than any in the last 8 years.  Very impressive snow piling up in the Cascades isn’t it?  And I always love the reaction I get from people when I tell them about the 39" one-day snowfall record in Oregon.  Not in the mountains, but near sea-level at Bonneville Dam.  There had already been 14" snow the day before, and more followed the next day.  On the 11th (2 days later), there was 63" of snow on the ground at Bonneville Dam!  You "old" timers probably remember the news video like I do…that telephone booth in Cascade Locks covered almost to the roof, and travelers stranded for days in the Gorge.  Fun times eh???  As I recall I was an 11 year old weather geek, sitting in the rain in Mt. Angel at the time…wishing so badly I lived in the Gorge.  Now, we just need to do it again someday!  Mark Nelsen

Up & Down Snow Level

January 8, 2008

SnapshotTonight was fun (when isn’t it in a La Nina winter?).  A secondary cold front moved inland during the commute time, bringing a batch of showers, windshift, and WARMER temps.  It finally mixed out the cool air that was trapped near the surface all day.  Then, over the last 4 hours or so, temps have been falling again as the cool air works in behind the front.  So it appears the snow levels are once again below 2,000′ this evening.  However, models and the satellite loop imply showers will die down towards sunrise.  So if you’re hoping for snow, it’s going to be tough to get it below 1,500′.

Our next system moves in tomorrow evening with a warmer start than last night’s storm.  So no snow much below 2,000′.  Milder weather Thursday-Saturday, then ridging builds in starting Sunday.  Models are all over the place for Monday and Tuesday.  ECMWF has a much sharper and colder system dropping in over the West Coast.  GFS shunts if farther east with just some rain.   We’ll see.

But BOTH models agree on strong ridging after Tuesday for nice and dry weather plus east wind…Mark Nelsen

Another Dance With Snow

January 7, 2008

SnapshotSnapshot2A bit of excitement tonight with the rain/snow mix.  Seems like we’ve done this a bunch this year;  Pacific weather system moves in over a cold atmosphere, giving us a brief "snow episode" for a few hours, then the warming southwest flow kicks in and it’s all over.  Just a tease again for the lowest elevations.
Quite a dramatic change in the next 4 hours is shown by all models.  By 4am the snow level over the Western Valleys should be around 4,000!  Strong southwest onshore flow kicks in after 2am, pushing our lowland temps into the lower 40’s by daybreak.
Another similar system Wednesday PM and Thursday will be slightly warmer.
Long range maps continue to show some sort of ridging the 2nd half of the weekend and early next week.  I doubt this will be a long-lived event since several times in December we saw maps forecast a big ridge and then it quickly went away.

There is still not sign of a big arctic blast.  For those of you hoping for a "good old fashioned" cold wave with highs in the 20’s and maybe some snow?  You’ve got about 5 weeks to go.  By the 2nd week of February it’s tough to keep high temperatures in the 20’s as the sun angle climbs.  Of course reality says there’s no reason we couldn’t have the coldest weather in 20 years coming the last week of January…who knows?  That’s what makes weather so interesting to me…Mark Nelsen