Another Year Gone…

December 31, 2007

SnapshotSnapshot2A bunch of Portland weather geeks got together at the NWS on Saturday…here is their group picture.  Now you can put a few faces with names that regularly appear in the comments.  Sorry I couldn’t make it, I had walls to paint and trim to nail.  But what a motley crew eh?  You can click on the picture for the full resolution.

Well, we are just a few hours away from the year 2008, but I really don’t have much to be sad about.  2007 treated me well and I hope/pray for more of the same this upcoming year.
I did learn something today;  DON’T park in front of a sign that says "Don’t Park In Front of This Gate!" .  Let me explain…

I woke up to beautiful sunshine early (for me) at 7:30 or so.  With fresh snow on the ground and much more a thousand feet up, I figured it was early in the day or never for some quick X-Country skiing.  I headed up Larch Mtn. Road east of Corbett, made it to where the snow was just scraping the bottom of my Subaru, and found a spot to park off the road and out of the way.  In front of the aforementioned gate.  Not a soul in sight, blue skies, and a couple feet of snow on the ground, what could be better?  Of course no loggers are going to work on New Year’s Eve Day with all that snow on the ground right?  Nah…so I enjoyed the skiing for an hour or so, came back down and saw my car had been moved (with alarm on) about 20 feet.  There were 3-4 pickups and some irritated-looking guys standing around.  Oops…well, turns out they were real nice guys and didn’t see the need to call the towing company.  Instead they plowed out the turnaround area and we talked weather (of course).  That was pretty generous considering what an idiot I was parking on the road to their operation.  So I have to give a shout-out to Tim Baker (Baker Logging) and I think it was Daniels Logging from the Aims/Sandy area for not crumpling my car with their bulldozer.

Now, on to weather…pretty slow, for about 36 more hours.  High pressure settling into the Intermountain region means gusty east wind is now blowing through the Gorge and spreading out through the metro area.  It has pretty much eliminated the fog & low clouds.  I notice lower dewpoints are even spreading south down the valley too, so other than high clouds, we have a bright, mostly sunny day for January 1st.

The cold front offshore is weakening as it moves in Wednesday morning before daybreak.  This one is much warmer than any in the last week, so it’s all rain west of the Cascades with a snow level up around 4,000′.  Above maybe 500′ at the west end of the Gorge and from Bonneville Dam out east at river level, it’ll be freezing rain or snow, more likely snow.  Probably a quick couple inches early Wednesday morning.  The flow never goes westerly later Wednesday or Thursday for that matter, so the cool air is going to get trapped in the Gorge through that period.  So this setup is not cold enough to get freezing rain out to Troutdale, but cold enough to make a mess in the Gorge itself.  Watch out if you’re traveling through there on Wednesday.

Back to wet & windy Thursday-early next week.  I notice two things.  As of the 12z/18zruns, several deep surface lows track south to north WELL offshore, similar to the big coastal windstorm early this month.  The first two have quite a southeasterly gradient;  not much strong  wind in the valleys.  The other is starting Saturday:  Back to cold/wet onshore flow.  Snow levels will probably come down into the hills again on Saturday, Sunday, or Monday.  So our wet La Nina pattern is going to continue…enjoy the sun tomorrow.

Don’t forget, if you’re bored and have nothing to do, come on out to the Oregon Zoo at 11am tomorrow and watch the weather guys in town get their hind ends frozen in the polar bear pool!  Mark Nelsen

Snow Totals Sunday

December 30, 2007

January2004_035 If you have at least 1/2", please put your snow totals only in these comments.  We need several things:



The picture is NOT from today’s snow in the hills…it’s my car stuck in the snow/ice during the January 2004 ice storm.

Big Snow Weekend in Cascades

December 28, 2007

SnapshotIt’s looking as if this last cold storm of the 2 week string will be the biggest for the Cascades.  Not such a big deal in the lowlands with less than 1" of rain though.  The 00z NAM shows 850mb westerly wind (around 4,500′) at or above 45 mph from 4pm Saturday to 4pm Sunday.  At times it averages over 55 mph!  This is very strong for the mountains and will probably squeeze out incredible amounts of moisture.  Our RPM model seems to agree.  It says 25-30" of snow accumulation in the Cascades by 7pm Sunday!  This is the most I’ve seen it forecast for any of these storms.  Sunday and Monday are going to be big powder days!  And you get sun with the powder on Monday as high pressure settles in.  I know thicknesses and 850mb temps support snow to 1,000′ or slightly below Sunday, but it’s a heck of an onshore southwest flow all the way through the evening.  Way too much mixing to get low level snow if you ask me…but at/above 1,000′ it’s more likely, especially in the orographic areas against the Coast and Cascade range foothills.  That’s why I downplayed the chance of snow in the metro area Sunday.  Moisture probably disappears soon after sunset Sunday too.

Speaking of high pressure, it quickly builds over the Intermountain Region later Monday and is quite strong by New Year’s Morning.  Looks like 10-12 millibars are likely through the Gorge on Tuesday and Wednesday with a very chilly airmass trapped in east of the mountains.  This will be the first time we see gusts over 70 mph in the Gorge this winter.  This is probably not the pattern that gives us downslope wind off the Cascades.  So not much east wind west of I-5…strictly a Gorge/East Metro event.

Now you’ll notice I put a 38 for a high Wednesday.   Assuming a system moves in from the west as forecast, the airmass east of the Cascades should be cold enough to produce freezing rain or snow in the Gorge.  It’s a bit too early for details, but some freezing rain is likely at the west end of the Gorge and POSSIBLY the portion of the metro area near the Gorge…definitely not a snow setup with warm air above.

The brief break in the weather sure isn’t going to last long!  Long range models throw us right back under the "storm train" beginning Thursday.  As always each model is different, but they all have powerful areas of low pressure moving quite close or over the West Coast.  Lots more fun on the way in this La Nina winter!  Next post on Monday…Mark Nelsen

Where’s the Snow?

December 27, 2007

Snapshot2Polarbear_2Hopefully this is a fair assessment of my forecast from last night.  It’s the same graphic on the previous post with my notes on top.  My boss said "where’s the snow?" as soon as I showed up at work today.  It sure was a nice snowstorm up closer to 1,000′, but too bad things didn’t at least turn white down below.  But it’s time to move on, considering that only 2-3 degrees separated us from a little Portland snowstorm today!

Not much to talk about tonight and tomorrow…a weaker system moves into Southern Oregon tomorrow.  Then a much stronger area of low pressure tracks to our north late Saturday and early Sunday.  We should get quite a gusty south wind Saturday night and all day Sunday.  That’s why even though a 1,000′ or lower snow level is quite possible, I’m not too wound up about it.  A showery airmass with strong onshore flow means it’s going to be tough to get the snow level real low.

Lots of high pressure builds in to our east Monday-Wednesday…A big east wind event is coming.  Rob get the gradient watch dusted off!

As for the Polar Bear picture.  Next Tuesday, New Year’s Day, at 11am, several weather people in town will be taking the "polar bear plunge" into their pool up at the Oregon Zoo.  I would ASSUME that they clean out the hair and poop first, but maybe that’s asking too much.  Anyway, it’s a fundraiser for the zoo and it sounded like a fun/wacky thing to do.  Of course when you look at me don’t you think "fun & wacky"? 

I think Dave Salesky and Bruce Sussman (assuming he isn’t on his deathbed), will be joining me as well.  The pitch?  If you want to pony up a $500 donation, you can join me too, but only an additional 7 people are allowed in the pool.  So who’s first in line?  Any takers?  Go to the Polar Bear Plunge website for more details and to sign up.  Shauna suggested I have a big chunk of ice to toss around the pool like the bears do.  Of course she didn’t offer to join did she???  Mark Nelsen

Snow Totals Thursday

December 27, 2007

If you have at least 1", please put your snow totals only in these comments.  We need several things:



New Snow Totals (does not include leftover snow on ground, just today’s storm):

10-12"  Hills above Woodland (800-1000′)
6"    Hill above La Center (700′)
4"    Chehalem Mtn. (1,500′)
4"    North of Camas (1,000′)
3"    Mt. Scott (1,000′)
2.5"  Council Crest Park (900′)
2"    Prune Hill-Camas (750′)
2"    Corbett (1,050′)
2"    West Hills, Germantown/Skyline (950′)
2"    Ridgefield (300′)
1"    Happy Valley (600′)
1"    Cherryville/Marmot area (900′)   

Tough Snow Forecast

December 27, 2007

SnapshotSo here’s what I’m thinking for the big "storm" tomorrow.  The basic idea is that we are all going to see some white, like we did on Christmas Day, through the morning hours.  Assuming the precipitation falls at a significant clip, which it should, all of us should see some white on the ground as well.  That said, increasing southerly flow in the 1,000-2,000′ elevation (20-30 mph) is sure going to be fighting against the precipitation rate.  So this should be a snow event where elevation makes a tremendous difference in snow totals.  Notice I’m forecasting possibly 2-4" at the top of the West Hills, but maybe almost nothing down IN Portland "proper".  Put another way, if you want to go sledding tomorrow or build a snowman, I think you will probably need to be at least 500′ or above.
or another…I doubt we’ll have any travel issues on the main city roads/highways.  Only in the higher hills will you find slush and then totally snow covered roads as you get well above 500′.

The reason I don’t think we’ll have the 3-7" the NWS is forecasting are these:

1.  Airmass is pretty much the same (except for overnight cooling tonight) overhead that we had Christmas Day.  That was also a very marginal event, but produced a widespread dusting with only about 1 hour of steady moderate precip. 
2.  Precipitation appears to be quite light until early afternoon, not the real heavy stuff that could drag the 32 degree line down to the valley floor.  Yes, the precip. gets quite a bit heavier as the cold front approaches mid-late afternoon, but much stronger southerly wind gets going above the surface at the same time (notice 00z MM5-Cross-Section).
3.  Our RPM model here says the same thing…slightly too warm, especially after 10am. 

If we don’t get sustained and moderate precip in the morning, then we could end up with nothing in the city…hopefully that won’t be the case.

I think we all agree on this…it’s going to be a dramatic warmup with a gusty southerly wind after 4pm.  The snow level jumps up to 2,000′ and then stays above there until early Sunday.

Mark Nelsen

Heavy Snow Warning

December 26, 2007

This is just like the good old days!  NWS has a Heavy Snow Warning saying 3-6" will fall in the city.  Media will go nuts…hmm.  This should be fun…and someone, either me or the NWS, is probably going to get burned forecast-wise by tomorrow afternoon. 

Now remember I said FUN.  That’s why we all watch and/or forecast the weather.  Some healthy competition is good!  So don’t argue about it too much in the comments, just discuss below.

I’ll post my thoughts on tomorrow’s "snowstorm" this evening, AFTER the evening news shows.

Mark Nelsen