Last Night’s Storm; An Analysis

January 18, 2012

A strange thing happened today…my coworkers kept saying “good job!”, or “you guys really nailed that storm!”.

Hmmm, now I’ve mentioned in the past that I feel I get a bit to emotionally wrapped up into these events, and this time I felt like in the end I really missed it.  So why the disparity between how I felt I did and what others thought?

1. In my mind, and alluded to in this blog yesterday, I really thought we’d only get very brief light accumulations for the bulk of the metro area.  Of course I had 1-3″ in the forecast during the 6pm show yesterday (so did Steph).  So technically the actual forecast (that 50,000 tv viewers and online viewers at that time saw) was far more than I really thought we would get.  A large part of the metro area DID get a total in that range.  I updated the totals up above.  At least all of the west metro, south, and much of inner east/southeast metro.  And it did not snow south of Wilsonville which was a perfect forecast for all of you in Salem/Woodburn etc…

2. This is the main point:   I, and probably many of you, focused on “how much snow was coming”.  That’s what weather geeks do.  And if it was a snowstorm that was coming for the day (to play in) most other people do as well.  Apparently most of our viewers, and just about everyone I work with seemed to focus on “snow overnight, then a quick warmup with no major issues for the morning commute“.  That’s exactly what happened, most areas transitioned to rain quickly after 1-2am, and the heavy rain melted enough of the snow to avoid a mess.  I didn’t realize that many of my co-workers were thinking we might be totally wrong and it would be 30 degrees and heavy snow at 8am. 

So what went right?  The Winners:

  1. Timing in general, it happened a little faster than I expected, rain to snow, then back to rain.  But models did very well.
  2. Mesoscale models clearly showed a changeover to snow as a distinct possibility, they are getting better and better!
  3. Heaviest totals to the north and west of the metro area.  Lots of 12-15″ totals above Scappoose, Vernonia, Amboy etc…
  4. No snow south of southern metro area.  1/2″ at Sherwood is the farthest south I saw.  None in Wilsonville/Canby.
  5. Quick warmup with south wind today.  I remember seeing a comment on here a day or two ago thinking that 50 was way too warm of a forecast for today.  It hit at least 53 at PDX.
  6. Positioning of the surface low…great job most models!  Came inland between Astoria and Hoquiam.  The NAM was a little far south, and several days out the GFS/ECMWF/GEM were better than the much farther south NAM.
  7. Heavy snow (10″+) in the right places as mentioned before, plus the 12-18″ in the Hood River Valley was a nice verification to see.
  8. This blog…no drama or major issues as we’ve often see in the past.

What went wrong?

  1. More snow than expected eastern metro and Clark County.  3-5″ east of I-205 was more than expected.  I didn’t expect the 3-5″ totals in east Vancouver, Camas, and Hazel Dell areas.  As mentioned earlier though, maybe much of the public didn’t care since it was late at night and melting quickly by daybreak.
  2. Me saying “my gut feeling is we get very little snow” on the evening broadcast.  Should have just kept my mouth closed and the forecast would have basically been okay.

So I’d rank it a 30% bust, but 70% fine forecast.  Feel free to disagree in the comments, you know I’m not easily offended.

By the way, has anyone noticed the very cold arctic air creeping farther south than any model shows into north central and northeast Oregon this evening???  More on that and how it affects the Gorge forecast on a post later this evening.

Chief Meteorologist Mark Nelsen


Wednesday Morning Storm Update

January 18, 2012

It’s the day after the storm, or for some of you the storm is still ongoing…

If you’re just checking in for a forecast, it’s straightforward for the metro area: Showers and windy the rest of today, south wind gusts should stay below 40 mph.  A balmy high between 45 and 50 degrees.

 Here are some highlights of the storm so far:

– Heavier snowfall than expected of course here in the metro area.  Looks like widespread 1-5″ totals.

– It DID change to rain around 1-3 am, so at least that part of the forecast turned out okay.

-It DID snow heaviest out against the Coast Range…I just got one report of 11″ on the west side of Forest Grove.

-The low pressure center is just north of Astoria right now, moving onshore.  Models did really well with that, especially the WRF-GFS.  NAM was slightly too far south in the end.

-South wind is picking up across the metro area right now and it’ll be quite windy through the afternoon, pushing temps up around 50 degrees.

– Check out those coastal gusts!  109-110 mph at spots on the central coast, lots of 80+ reports.

– Mountain snow:  Mt. Hood Meadows has received 37″ since 5am yesterday…must be close to it’s all time record.  I think that’s somewhere in the 30s for a 24 hour total.

Another surface low moves in to our south tomorrow morning.  This pulls fresh cold air into the eastern Gorge.  If so, you folks in the central/eastern Gorge could have another foot on the way.  It might be a significant ice storm at the western end towards tomorrow morning too as the east wind gets going (not in metro area).

What did go wrong?  I should have trusted those mesoscale models better.  They clearly showed a snow profile.

I had the worst drive ever on the way home last night.  Extremely heavy snowfall from Beaverton down Hwy. 26 onto 405…real slow.  Then the Marquam Bridge was just closed as I approached.  On SB 405 that forces you onto SB 5.  Did you know there’s no exit for about 2 miles until you get way up to the Terwilliger exit?  So I drove down the hill from there onto OR 43, across a still and snowy Sellwood Bridge, through an empty Sellwood, then through Milwaukie (it actually snow there last night), a very slow drive all the way to I205 & 224 entrance ramp.  Meanwhile, here and there were vehicles stuck in the deep slush/snow.  Up I205 to 84.  Slow drive in blinding snow to Corbett exit.  Halfway up Corbett hill a guy is sitting in the middle with flashers on.  I ask if he needs help “no, I’m just from Portland and checking out my 4 wheel drive in the woods”.  Hmmm, okay, move on.  I get within a mile of home in the middle of nowhere, dodging trees hanging way down over the road.  Come around a corner and Bam!…a large tree fallen across the road.  I back up, park, start walking.  All you can hear is occasional cracking from limbs and trees falling.  Just as I start, a Reliance Connects phone company crew drives down looking for a way to get to their equipment.  They have a chainsaw!  So at 1:30am, in a suit and boots, I’m helping remove a tree off the road, which is somewhere 8″ or so down.  What  a weird experience .  I got home and to bed around 2:30am.

Chief Meteorologist Mark Nelsen 


Snow Total Tuesday Night

January 18, 2012

 Keep discussing weather on previous posts.

1. Fresh snow received between 5pm & this morning

2. Total (for those of you in the hills that have a lot more)

3. Location

4.  Elevation if you are up close to 1,000′ or higher.

And don’t forget, the first time you post a comment, or use a different IP address, your comment is held for moderation.  After that you can post anytime.  It may be a couple hours until I get to your comment.  This keeps the “spam issues” away.

This is what we have so far. Sometimes two or more of you reported from the same location; I had to choose one of those, don’t hate on me if I didn’t use yours!

NW OF METRO AREA:
8″ Castle Rock
5″ Longview
12″ Columbia City
12″ Vernonia
10″ Scappoose

CLARK COUNTY
3″ Woodland
5″ Battle Ground
12″ Amboy
16″ Yacolt
6″ Hockinson
4″ Hazel Dell
2″ Vancouver
3″ E. Vancouver
4.5″ Camas

WEST SIDE METRO AREA
8-11″ Forest Grove
3″ Cornelius
2″ Hillsboro
2″ Beaverton
4″ Cooper Mtn
0.5″ Sherwood
1.5″ SW Portland
4″ West Hills

CENTRAL AND EAST METRO AREA:
2.2″ Official Portland Total at NWS
5″ St. Johns
2.5″ N Portland
2.5″ SE Portland
3.5″ E Portland
2.5″ Clackamas
4″ Happy Valley
4″ Sellwood
2″ Milwaukie
2″ Oregon City
5″ Gresham
4″ Fairview
4″ Troutdale
7″ Corbett
12″ Sandy

None in or south of Wilsonville/Canby areas.


Quick 9:30pm Update

January 17, 2012

Very little time (that little TV thing gets in the way of a good blogging experience).

Lots of snow falling in a few places I didn’t expect so much, and it’s not falling where I did.  That’s okay I haven’t freaked out…yet.

Wayne Garcia just came in to let me know something along the lines of  “you know it’s okay to change course instead of going down with the ship…”  Thats the quality encouragment I get from my coworkers.

Lots of snow falling and sticking in Clark County and most of the metro area north of Oregon City to Wilsonville, but not much…yet (slightly warmer) over in Washington County.

South wind is gone, but no east wind yet.  That was expected.

At 1,800′ it’s 32 degrees!  Folks, it doesn’t get any more more “marginal” than this!  In a well-mixed atmosphere it would be about 40 or so down here in the lowlands, but the heavier precipitation rates are allowing the snowflakes to survive much lower.

I mentioned I’m not freaking out for two reasons:  The WRF-GFS speeded up the timing of slightly warmer air moving in overhead, to right after 1am (but no south wind at that time at the surface).  Just enough to possibly change flakes back to mainly rain or a mix.  The other reason is that our RPM continues to show very gradual warming (up above, not at the surface again) through the night too.  Hmmm, combine that with the surprisingly mild tower temps and we could still escape without more than just trace to a few inches.

OR, I’m going down with the ship and there will be 10 inches of snow on the ground in Portland by 4am.

Chief Meteorologist Mark Nelsen


Tuesday Morning Snow Update

January 17, 2012

An exciting morning with lots of heavy snow in the hills, and snow in the very lowest elevations.  It’s really adding up in the hills; I have 6″ on the ground here at 1,000′, and I see reports up around 10″ in other hills higher up.  The heavy showers ALMOST overcame the strong southwest wind, which advects in warmer air off the Pacific, what an epic battle!    Here’s the forecast for those of you just tuning in for the basics:

Snow and mixed snow/rain showers continue through the day, although they die down quite a bit this afternoon.
The sticking snow level rises slightly again like it did yesterday afternoon, so roads in the hills that have some light snow should only get better as the day goes on. 

Evening commute should be fine for metro area highways and most roads too.

TODAY:  Rain/snow showers in the lowest elevations.  Still, light dusting possible briefly anywhere before noon.  Another 2-4″ near/above 1,000′…it’s getting pretty deep up in the hills.  Be aware that’s a forecast of nothing at sea level to 2-4″ at 1,000′.  You don’t just suddenly get 2-4″ at that higher elevation and nothing 200′ below, amounts will vary between those elevations AND, MORE IMPORTANT, depend on precipitation intensity.  So yes, 500′ could still get somewhere between zero and 4″ possibly. 

THIS EVENING (Through at least 10pm):  Rain/snow showers, turning to steady rain/snow later…most sticking snow at/above 1,000′ through our 10pm show.  Light accumulations during this time on the hills, this will be the calmest period.

OVERNIGHT THROUGH 7:00 AM:  Winter Storm Watch is still up, and NWS will probably upgrade to a Winter Storm Warning mid-afternoon to be safe.  I still think we’ll escape a big snow event here in Portland, but it’s going to be VERY CLOSESo I’ll forecast 1-3″ of heavy wet snow possible anywhere from Wilsonville north through Clark County (all of the metro area) between Midnight and 5am.   No snow for Wilsonville south to Salem.  Once again, gut feeling is we get little or nothing here, but it’s safest to forecast (Dec 29, 2009) a few inches in the dark of night.

This still looks much better in far Western Washington County (Forest Grove, Banks, maybe Hillsboro too), Columbia County (Vernonia, Sacappoose, St. Helens), and Longview north through SW Washington.  The Gorge is just going to get hammered!  Possibly 4-8″ west of Hillsboro and Scappoose/St. Helens and Longview.  Vernonia has a lot of snow on the ground now, and could see another 8-12″!  Just out of our viewing area, north of Longview, 8-12″ is likely, a historic storm up there.  In the Gorge from Cascade Locks to The Dalles, I could see a total of 18-24″ by Wednesday afternoon.

AFTER 7:00 AM TOMORROW:  The plan is for a quick warmup to rain.  High around 45.  NWS has a High Wind Watch up for the Central/Southern Willamette Valley.  This MIGHT be tomorrow’s big story, but not all of our models have such strong wind.  The Gorge stays snowy tomorrow.

Now, on to the technical stuff:

A very challenging forecast continues.  I’m pretty happy the overnight forecast worked out well with slightly warmer temps keeping most of the sticking snow above the lowest elevations.  Lots more showers through mid-afternoon, then models indicate a brief break before steadier precipitation heads in this evening.  Satellite loop clearly shows the approaching system heading towards us.  This one will be far juicier with 1.00-1.50″ precipitation between this evening and midday Wednesday!  The areas that see most or all of that fall as snow are just going to get hammered.  That includes Cascades, central/eastern Gorge, and the North Coast Range plus foothills (as mentioned in the forecast above).

We finally have pretty much perfect agreement in the models for the overnight/Wednesday morning system.  A surface low will track to right around Astoria by 10am, then fall apart later in the day over Washington.  Perfect setup for a historic snowstorm just to the east and north of the center.  That means SW Washington REALLY gets nailed, as well as the North Coast Range of Oregon and Willapa Hills.  With this setup, as the low approaches the coast tonight, we lose our south wind during the evening hours, and then over the metro area it goes calm through part of the night, then a light SE or E wind picks up towards daybreak.  Two things to point out:  one is that it’s not a cold east wind coming through the Gorge and it won’t be very strong, so we don’t have one of those setups with a gusty gorge wind and temps dropping all night.  In fact it’ll be a “mild” west wind through the Gorge until midnight.  What’s really going on is during this period? The flow of warmer air moving in with the southwest wind stops, allowing the near/below freezing temps to extend in a column from the 1,000′ freezing level all the way down to the surface.  This is most likely during the very heavy precipitation midnight and beyond.  Assuming the low positioning is correct, this ends by 7am as strong southerly wind punches through overhead, raising the snow level way above 2,000′ (eventually 4,000′ or more by midday).  Here’s the sounding off the WRF-GFS at the coldest forecast point for both Portland and Salem (around 4am):  Isothermal (near 32 degrees) profile at Portland, but well above freezing at Salem in the lowest 1,500′.  Click for a better view, or your eyes are going to hurt. 

 IF our models are incorrect and the low decides to come into Tillamook or even slightly farther south, we get a ton of snow here like we currently expect for Longview to Olympia, but I see no reason to go for that solution.  If the low is any farther north, that just shortens the period in which we could get snowfall in our neck of the woods.  So, with all that info I like what our RPM model and WRF-GFS show for snowfall.  First, from 4pm today through 4pm Wednesday:

Notice we are right on the line here, the Gorge and SW Washington get dumped on.  Here’s another issue, the GFS and WRF-GFS keep marginally cold air in place over the Columbia River Gorge through tomorrow night and Thursday as another system moves through, note the 4pm tomorrow through 4pm Thursday snow forecast:

The MM5-NAM doesn’t do that since it has a much stronger low center tomorrow running into eastern Washington, wiping out the cold air eastside.

Speaking of that MM5-NAM, it’s the one model that has a huge southerly pressure gradient through the Willamette Valley as the low tracks by to the north.    Note the map:

If this actually occurs, there will be a damaging windstorm in the valley tomorrow, possibly as far north as Portland.  This shows 11-12 millibars just from Longview down to Salem with perfect east-west orientation of the isobars.  Other models are not as intense and we have the 00z runs to see what happens.  Interesting  to note that there is a High Wind Watch out for the central/southern Willamette Valley tomorrow; that alone would cause us to go into BREAKING WEATHER mode, but this little pesky snow thing is drawing the newsies attention elsewhere.

Unless some surprise occurs, I probably won’t post again until 9pm or so.  It’s going to be a long day in the newsroom!

Chief Meteorologist Mark Nelsen


Quick Evening Update

January 16, 2012

An extremely busy evening both on TV and off means my email Inbox is jammed…I’ll get to those later this week.

As mentioned this morning, models have come into good agreement and it’s even better on the new 00z runs.  More on tomorrow night’s big system in a minute.

This evening everything is going according to plan, a deepening surface low to the north is giving us a gusty southerly wind.  Temps are near their daytime highs as a result.  We just hit 36 at the station in northern Beaverton, the high for the day.  Our KPTV Tower temps have been rising since early afternoon and mesoscale models show the low level atmosphere maybe warming another 2 degrees by daybreak.  That mostly eliminates the chance for sticking snow at the lowest elevations.  One hitch is much heavier precipitation forecast to arrive between 7am and 10am.  This will be similar to this afternoon; heavy wet flakes will stick lower than they will tonight.  That’s why I said Trace-1″ at the lowest elevations by morning and 1-3″ up around 1,000′ and above.  The southerly wind may die down right around that time as well.

The rest of tomorrow looks similar to today temp & precip-wise.  With a light south wind we rise up to around 40 degrees, or at least the upper 30s. 

Good news for tomorrow night and early Wednesday morning.  All models now move the surface low up to somewhere near Astoria or a little farther north.  As the steady precipitation settles in after sunset tomorrow, the sticking snow level will probably be up around 1,000′.  Then a switch to light easterly flow between 10pm and 4am could allow the column of air overhead to drop to 32 degrees all the way down.  Model soundings are still showing this, just like I showed on the previous post.  It’s a very close call, but considering there will be no influx of cold/dry air from the Gorge, I’m not excited about a big metro-wide snowstorm.  I won’t be surprised if there is only a trace or less once again across the bulk of the lowest elevations from the Columbia River south.  I feel the best place to hold onto the cold air will be up against the Coast Range and then north of the Columbia River, up into Clark County.  Forget about it Salem…too mild down there (just barely).  The WRF-GFS and our RPM do not show accumulating snow in Portland, but it’s quite close!  Check out the WRF-GFS snowfall accumulation graphic valid from tomorrow at 4am to Wednesday 4am:

Once again, best chance north and west of Portland. 

Here’s the forecast graphic I used at 10pm for that period:

A southerly wind should move into here Wednesday midday at the latest.  Depending on the depth of the surface low, we could either have just southerly breezes or a significant wind event.  We can worry about that tomorrow.


Winter Storm Watch Thoughts

January 16, 2012

This slideshow requires JavaScript.

After all these days, we finally have an agreement in the models for the critical Tuesday night through Wednesday forecast.  I’ve put in a slide show which takes the ECMWF, GEM, GFS, & NAM for 18z (10am) Wednesday on the same map projection.  Note that they all are much closer on a surface low moving up against the Oregon/Washington Coastline by Wednesday morning.  The NAM has finally turned warmer with 850mb temps in the -7 to -8 range tomorrow, although that’s still slightly colder than the GFS/ECMWF.

So what does it mean?

1. The National Weather Service has issued a Winter Storm Watch for much of Northwest Oregon and Southwest Washington for this storm.  I think that is a little much, but they do need to err on the side of caution since that’s their job.  Probably a good move since  it’s only a WATCH, not a WARNING.  That means if it becomes obvious there is only rain coming in the lowlands, they can just change it to a Winter Weather Advisory for the hills.

2.  All of these models are very marginal for snow here in Portland, especially the GFS.  That said, even the ECMWF/GFS 850mb temps around -4 to -5 with 6-10 hours of easterly flow could change us over to snow.  Note the 12z WRF-GFS sounding for 1am Wednesday morning.  That’s REALLY close to snow.  Most important, I told myself I wouldn’t make the “December 29th mistake” again.  When it’s marginal, I’m going to tell the public so instead of just taking them along with my “weather gambling forecast” they can be prepared in case I’m slightly off.

3.  Due to that, I think it will probably not stick Tuesday night and Wednesday morning for most of the metro area, but it’s going to be very close!  Luckily it should happen mainly at night too.  And this forecast is subject to change the next 24 hours if models come any farther south with the surface low.

Where could we get significant accumulation of snow?  The central/eastern Columbia River Gorge (10″+ possible).  Longview and northward in Southwest Washington (4″+), and the western parts of Washington/Columbia counties, and maybe Scappoose/St. Helens too.  A little bit of the “Forest Grove Effect”, where cooler air pools up against the east side of the Coast Range.  Those spots could see 4″+ as well.

Quick warming on all models Wednesday afternoon.  A south wind with 850mb temps above zero is 50 degrees easy.   Gusts could be over 40 mph depending on the low placement.  Interesting to note the NAM-GFS from UW is much stronger and farther south with the low than NOAA’s version of the NAM.

Oh yeah, as for the next 24 hours, I haven’t changed my thinking much:

REST OF TODAY:  Snow showers pick up later…increasing southerly wind lifts sticking snow level up around 1,000′.  Highs near 40

TONIGHT & TUESDAY A.M. COMMUTE:  Snow showers, snow level doesn’t lower much below 1,000′, so 1-2″ new on the hills closer to 1,000′ and above.  No freezing in the lower elevations.  That’s because of the mild southerly wind continuing to blow.

TUESDAY:  Mixed rain/snow showers all day, sticking snow only up around 1,000′ or even a little higher by afternoon…1-3″ on the higher hills only.

Chief Meteorologist Mark Nelsen