Slower Weather Ahead

December 30, 2005

Looking at models for the weekend and all of next week…I see a slowing down of our weather pattern, and a continuation of mild temperatures.  Looks like in the big picture the Western US ridge is going to attempt a comeback over the next 7-10 days.  Not enough to shut down the precip again, but enough to keep approaching weather systems quite weak after Sunday.   So you arctic air lovers will have to wait quite awhile.  We I feel more energetic next week we can discuss that in more detail (RE: Ashley’s comment in the previous post…I got exhausted just reading it my friend)

Speaking of Sunday…the deep low pressure looks impressive but:  1.  It moves very slowly along the coast, 2.  It is weakening as it approaches,  3.  It veers well north into Vancouver.  So I don’t expect strong inland winds with this one, just another round of rain.

Enjoy the New Year…Here’s to a good windstorm (65+ mph at PDX but nobody gets hurt), a big blast of arctic air in late January that gives us a high of 18 at PDX.  And a good 10" snowfall at 22 degrees.  See, I don’t ask for too much right?


Questions Answered II

December 29, 2005

We’ll talk current weather, then get to those "accidentally-erased questions".

00z models keep the solid rain in here much of tomorrow.  I think we’ll see lots of localized small street flooding, but not enough for more than maybe 5-7 rivers approach or go over flood stage.  Plus, we get a break Saturday and lower snow level to help things out.  Wind shouldn’t get too wild UNLESS an unforecast low pressure center suddenly develops along tomorrow’s front sitting over us.  If one were to develop and move along the front into Western Washington…that would be a problem for the western valleys.

Looks like the moisture gets shunted a bit farther north next week, so we stay mild, but no real heavy rain.

Okay, let’s try again with those questions you’ve asked:

1.  (During the cold spell)  "If there is warm air higher up with cold air down here at sea level, how come there was a lot more ice in the West Hills, SW Portland, Lake Oswego Hills than down in the middle of the City?"

Very good question.  But you have to really think of the setup during ice storms (or any time cold air is flowing out of the Gorge) as two distinct airmasses.  And within any air mass the temperature goes down as you rise in elevation.  So on that Monday morning, temperatures right in downtown PD were about 34, it was 32 up in SW Portland and L.O.  And the top of the West Hills were about 30 degrees.  Lots more ice in those places.  Once you hit the inversion around 2000′, temperatures jumped to around 50 degrees.  But continue going up and it would gradually drop off 3-4 degrees for every thousand feet.

2.  "Will U2 still hold their concert (Monday, Dec. 19th)?"

Amazing that several people asked me about that.  I just stick to weather.  Forecasting Bono’s next move is too tough for me to tackle.

3.  "What about the rest of this winter…will we see any more ice or snow in Stumptown?" Submitted by Wayne Garcia

By the way, Wayne is as nice a guy in person as he seems on TV.  Too bad he didn’t offer a pair of dice at the same time.  Who could have said November 30th we’d see a mini ice storm the 3rd week of December, but temps in the 50′s the following week?  No matter what you hear, no one I know can reliably forecast more than maybe 7-10 days in the future (depending on the weather pattern).  And once again…forget those sites on the internet that claim they can give you exact conditions 7 days from now.  I blogged on that subject a few weeks back.  I WILL say that not a single model has any sort of unusually cold or arctic air patterns through the first 10 days of January.

4.  Is a TV station in town really shutting down their news department?

Most likely idle rumors started by bored TV newsfolks, but there is that rumor going around Portland TV circles.  It sure won’t be KPTV, we know that.


A Shorter Post

December 28, 2005

You’ve been cheated tonight…

I just finished a nice little question & answer blog posting tonight, in fact I was quite proud of the ground I covered.  Lots of good meteorological information…interspersed with bizarre dry humor.   Then while having a conversation in the weather center with a co-worker I apparently closed the window…WITHOUT hitting the POST button.  Ooops!  Now I’m so irritated at myself and traumatized by the whole situation that it’s amazing I was able to give any sort of valuable weather information at 10pm.  But I pulled through for the team.

I will start all over tomorrow, but for tonight we’ll just have to talk current weather.

00z runs of MM5-UW and ETA show a nice little low curving north tomorrow night outside the "zone of danger" for western valley damaging wind.  But what a hunk of moisture is headed our way…we could easily see 1.50" from Thursday night-Saturday AM.  Funny how quickly we make up our December rain deficit.  The westerly flow appears to be slightly more "splitty" next week, so we’ll see more rain, but storms shouldn’t be quite as intense.  Either way, Friday should be a wet & windy weather day.

Now that wasn’t so bad was it?  Now on to….POST


Storm #4 Arrives

December 27, 2005

I’m surprised by the strength of the south winds arriving at Coos Bay this evening.  North Bend is gusting near 60…pretty rare for that spot.  They should spread quickly up the coast in the next few hours.  The actual low pressure center is far enough offshore that damaging winds (50+ mph gusts) are very unlikely inland.

A brief break the next couple of days and then another 2-3 waves move through Friday-Sunday.  We’ll watch each of these carefully for any signs of strong development or a track close enough to the coastline to bring high winds into the interior.

For you arctic air freaks (I mean that in an endearing way), still no sign in ANY long range model of cold air moving into the Northwest.  Looks like early January will see normal or slightly above normal temps.  Sorry kiddies…Mark


Update: Wednesday Storm?

December 26, 2005

9pm:  00z MM5-UW model runs just in are quite a bit stronger for the Wednesday system.  Rapid deepening and moving in the preferred damaging windstorm track (well inside 130W) and a movement towards the tip of NW Washington definitely needs to be watched pretty closely.  If the GFS version is right I’d expect gusts to 80+ mph on far north coast and gusts to 50 mph north of PDX (Kelso to Olympia).  A slightly closer track would bring strong winds into the interior of Western Oregon.  We’ll see…


Looking for Windstorms

December 26, 2005

6:00pm  Very active weather pattern continues through the beginning of the New Year.  Last few model runs seem to hone in on 4 more organized frontal systems from tonight-Saturday.  As of this evening, I don’t see any one producing wind gusts stronger than 40 mph in the Western Valleys.  BUT, this is the pattern that can produce surprises.

Hard to believe, but if this blog doesn’t satiate your weather geek needs, try this site:

http://oregonstate.edu/~readw/

Wolf Read has compiled an excellent of history of Northwest Windstorms over the years, including maps.  Track maps show where our most dangerous winter storms have originated and what track they take.  You could spend hours perusing all the storms with your favorite beverage in hand (I have!).

What I noticed most today was the continuing warmth.  The steady stream of moist/mild air from the southwest keeps the 50s coming.  Not the decade of course, but the temps.  A week ago we were struggling to get much above 32 here in Portland, and now 50-55 seems very nice. 

We ARE almost to what I call the "Portland Winter Halfway Point".  Our chance for low elevation snow is really only from mid-November to late February.  That means once we reach the first week of January (next week), we are halfway through our "danger period" for arctic air or significant snow.  We’ve had it easy so far this year…only 1" of snow officially last week.  I don’t see a single weather map that shows a return to anything close to snow or cold here in the next 7-10 days.


Christmas Morning Surprise (Wind)

December 25, 2005

I should have paid closer attention…2 of gifts from my wife last night included:  a storm survival kit for the house and a nightlight/emergency flashlight combo for power outages.  Hmm….funny that I wake up at 4am to electricity buzzing off/on/halfway on etc…also flashes in the sky and then it was pretty obvious.  A very warm wind blowing from the southwest means some sort of surprise windstorm.

The low pressure center that travelled just offshore last night ended up stronger than expected, and when the cold front moved through early this morning, strong winds above mixed down to here on the ground.  I’ve scanned all sorts of observations, including Forest Service sensors in the mountains and ODOT sensors.  I can’t find a single gust above 50 mph anywhere below 4,000′ here in Northwest Oregon.  Hard to believe that peak southwest wind gusts from 45-50 mph dropped dozens of trees and put 30,000 PGE customers out of power for Christmas Morning.  That’s the largest outage since the ice storm 2 years ago!  Just about all damage was confined to an area east of I-205/99E and west of the Cascades, and between I-84 on the north and Marion County on the south.  Clackamas and E. Multnomah County seemed to get the brunt of the outages.

Pressure gradients (actually observed, not forecast by models) seemed to barely even support winds that strong.  And even more interesting is that 50-60 mph easterly winds in some spots such as Gresham last week downed fewer trees than 40-50 mph southerly winds today.  I suppose it could be related to the fact that it’s been 6 years since PDX has seen a southerly wind gust over 50 mph.  Our trees have had it easy lately.  Maybe many of those would have gone down over the last few winters.   

The weather pattern stays very active through the first few days of 2006, so we’ll be watching closely for any strong areas of low pressure approaching the coastline.  There should be 5 good "waves" or chunks of energy moving through between Sunday evening (now) and Saturday Evening (New Year’s Eve).

By the way…the high of 63 degrees is the warmest Christmas Day since the 1980.  If you were here then, you may remember lots of flooding.  That’s the event where part of Mt. Hood washed down and washed out a good chunk of Highway 35 and several bridges in Hood River county.


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