Snowmageddon ’09 Wrap Up

February 26, 2009

It has been a really long day for me…I left the house around 8am and was in Keizer by 9:30 for the first of two school visits.  Then I've done all the shows tonight.  Is anyone crying for me yet?  I didn't think so, but I'm just a bit tired so a brief post tonight.

I'm pretty happy with the way the forecast turned out.  Models were right on with light amounts of moisture overnight.  We had .14" at PDX from 10pm last night to 4pm today.  But Salem got .48" at the airport; about 1/2 of that falling as sticking snow.  The higher elevations on the south side of the city and west hills had accumulations in the 2-4" range, so you see what some extra precipitation COULD have done up here.  Except for Forest Grove, which got around 2" in the lowest spots, it looks like all other low elevations in the Metro area had zero to 1".

One thing I didn't anticipate was the end of the showers and sudden clearing that moved in around daybreak.  It was early enough that temps dropped to near/below freezing out in the Tualatin Valley and northern Clark County, freezing the water on the roads.  I thought it was stay cloudier until midday.

Not much to talk about on the maps tonight…just milder southerly flow developing over the weekend in the upper atmosphere.  Easterly wind returns through the Gorge both Saturday and Sunday, but it shouldn't be too chilly this time with no inversion setting up eastside.  Models seem to want to mix us out nicely on Sunday for warmer temps…in the 55-60 degree range.

That's all for now, I have the day off tomorrow so the next post won't be until Monday…Mark Nelsen


Snowmageddon ’09 Wrap Up

February 26, 2009

It has been a really long day for me…I left the house around 8am and was in Keizer by 9:30 for the first of two school visits.  Then I've done all the shows tonight.  Is anyone crying for me yet?  I didn't think so, but I'm just a bit tired so a brief post tonight.

I'm pretty happy with the way the forecast turned out.  Models were right on with light amounts of moisture overnight.  We had .14" at PDX from 10pm last night to 4pm today.  But Salem got .48" at the airport; about 1/2 of that falling as sticking snow.  The higher elevations on the south side of the city and west hills had accumulations in the 2-4" range, so you see what some extra precipitation COULD have done up here.  Except for Forest Grove, which got around 2" in the lowest spots, it looks like all other low elevations in the Metro area had zero to 1".

One thing I didn't anticipate was the end of the showers and sudden clearing that moved in around daybreak.  It was early enough that temps dropped to near/below freezing out in the Tualatin Valley and northern Clark County, freezing the water on the roads.  I thought it was stay cloudier until midday.

Not much to talk about on the maps tonight…just milder southerly flow developing over the weekend in the upper atmosphere.  Easterly wind returns through the Gorge both Saturday and Sunday, but it shouldn't be too chilly this time with no inversion setting up eastside.  Models seem to want to mix us out nicely on Sunday for warmer temps…in the 55-60 degree range.

That's all for now, I have the day off tomorrow so the next post won't be until Monday…Mark Nelsen


Snow Totals

February 26, 2009

Not exactly a big snowstorm in the lowlands, but a few of you got more than 1/2".  If you did get that much, put the info here.

1.  Snow Depth

2.  Location (elevation if you know it too).

NO OTHER COMMENTS ON THIS POSTING PLEASE!


Snow Totals

February 26, 2009

Not exactly a big snowstorm in the lowlands, but a few of you got more than 1/2".  If you did get that much, put the info here.

1.  Snow Depth

2.  Location (elevation if you know it too).

NO OTHER COMMENTS ON THIS POSTING PLEASE!


Looking For Snow

February 25, 2009

Snapshot Here's something to think about in relation to tomorrow's possible snow.  This is the output from our RPM model from 12z today.  It's the precipitation output from 4am-1pm tomorrow.  Can you say orographic???  I'll post sometime this evening…Mark Nelsen

 

9:30pm Update:  Looks like things are working out pretty well this evening.  Cold air is moving in nicely with temps down into the 30s everywhere north and west of Portland.  Our 1900' tower temp is down to 31 degrees, which means over downtown Portland the snow level must be around 1200' or lower in the heavier showers.  As you go north and west the snow level is much lower, around 500 feet or even a bit lower based on reports from Longview, Vernonia, Battle Ground and Yamhill.  Keep those comments coming down below!  In situations like this I do try to read the comments to see who's getting a mix or all snow.  You can't get that off of official observations.  Too bad we can't pull out the Jim Bosley phone board and talk to you anymore…that would be so…1980s.  How many of you remember that?

00z Models have come in even drier for tomorrow.  Our RPM has a total of .07" precip from 4am-4pm tomorrow.  I have a gut feeling based in the IR imagery and models that after this inital surge of moisture the next few hours, we'll just see very light snow showers through midday tomorrow here in the valleys, and partly to mostly sunny skies by sunset (42 degree high due to that).  Weak showers and a Coast Range to our west in westerly flow have been bad news in the past couple of winters.  We have a cold enough atmosphere to get a good snowfall here in Portland, but I just think the moisture is lacking.  I HAVE noticed the nice surge of cold dry modified arctic air down into northwest Washington as far south as about a Hoquiam to Seattle line.  It would be nice if it would move down over us, but the surface low sliding down the Coast moves inland towards Olympia tonight and then dissolves into a trough that stays to our north tomorrow.  So we never lose our onshore flow the next 24 hours. 

We are done with the showers soon after midday tomorrow, then it's on to a rapidly warming atmosphere late Friday through the weekend.  A deep upper-level low forms well offshore, which pumps up the mild southerly flow.  March will come in with seasonal temps in the 50s Sunday…Mark Nelsen

 


Some Snow?

February 24, 2009

Snapshot Ahh, the good times are back this evening with some good heavy rain showers in spots (right over Steve Pierce's home).  And now we have the possibility of snow to low elevations tomorrow night and Thursday.  I just had the studs taken off my
"snow car", luckily it's a 4 wheel drive that'll do fine in a few inches of snow!  For tonight…more showers.  For tomorrow…more showers.  A nice slug of moisture to our southwest keeps the showers going overnight.  It still looks like the heaviest precipitation will be from the Columbia River south. 

     Then a sharp cold front moves into Northwest Oregon tomorrow afternoon.  This is the leading edge of a very cold maritime polar airmass.  Arctic air is already beginning to spill out of British Columbia between Vancouver Island and the Queen Charlotte Islands.  So we get an upper-level low and a surface low spinning up near Northern Vancouver Island later tomorrow.  These both pass overhead Thursday.  00z models all seem to be in agreement now on the movement.  The surface low comes inland around Astoria as it fills Thursday morning.  It's a really cold airmass!  850mb temps are somewhere around -8 to -9 deg. C.  That's usually cold enough to get snow to sea level if you can get rid of a mixing wind.  We still have a light southerly flow up the Willamette Valley tomorrow evening and Thursday because the low is staying farther north, but it's not exactly a raging south wind.  Heavy precipitation intensity always helps in these situations, or is sometimes the key factor to getting snow to low elevations.  With the westerly flow, the areas west of I-5 may have lighter precip.  In general I don't see a ton of heavy showers.  The steadiest precipitation should be in that 4am-10am time period Thursday…then we dry out in the afternoon (and warm up of course). 

Put these all together and this is what I get:  I think it'll be tough to get significant snow (>1") here in the lowest elevations of Portland, but all of us should see at least a dusting in the morning Thursday.  I'd say 1-3"+ snow is a done deal at/above 1,000' anywhere in our region, and anywhere in SW Washington north of Vancouver.  The Coast is a big question mark…there's no reason we shouldn't be able to get snow to the beaches, unless the southerly breezy from Astoria south kills it for you folks.  We have 24 more hours to keep digesting information for this little event too.

Beyond Thursday, pretty quiet.  A new upper level trough develops offshore Saturday through Monday.  There are some deep surface lows that linger way out over the Pacific, but they aren't really going anywhere in a hurry, so they aren't a high wind threat for us…Mark Nelsen


Some Snow?

February 24, 2009

Snapshot Ahh, the good times are back this evening with some good heavy rain showers in spots (right over Steve Pierce's home).  And now we have the possibility of snow to low elevations tomorrow night and Thursday.  I just had the studs taken off my
"snow car", luckily it's a 4 wheel drive that'll do fine in a few inches of snow!  For tonight…more showers.  For tomorrow…more showers.  A nice slug of moisture to our southwest keeps the showers going overnight.  It still looks like the heaviest precipitation will be from the Columbia River south. 

     Then a sharp cold front moves into Northwest Oregon tomorrow afternoon.  This is the leading edge of a very cold maritime polar airmass.  Arctic air is already beginning to spill out of British Columbia between Vancouver Island and the Queen Charlotte Islands.  So we get an upper-level low and a surface low spinning up near Northern Vancouver Island later tomorrow.  These both pass overhead Thursday.  00z models all seem to be in agreement now on the movement.  The surface low comes inland around Astoria as it fills Thursday morning.  It's a really cold airmass!  850mb temps are somewhere around -8 to -9 deg. C.  That's usually cold enough to get snow to sea level if you can get rid of a mixing wind.  We still have a light southerly flow up the Willamette Valley tomorrow evening and Thursday because the low is staying farther north, but it's not exactly a raging south wind.  Heavy precipitation intensity always helps in these situations, or is sometimes the key factor to getting snow to low elevations.  With the westerly flow, the areas west of I-5 may have lighter precip.  In general I don't see a ton of heavy showers.  The steadiest precipitation should be in that 4am-10am time period Thursday…then we dry out in the afternoon (and warm up of course). 

Put these all together and this is what I get:  I think it'll be tough to get significant snow (>1") here in the lowest elevations of Portland, but all of us should see at least a dusting in the morning Thursday.  I'd say 1-3"+ snow is a done deal at/above 1,000' anywhere in our region, and anywhere in SW Washington north of Vancouver.  The Coast is a big question mark…there's no reason we shouldn't be able to get snow to the beaches, unless the southerly breezy from Astoria south kills it for you folks.  We have 24 more hours to keep digesting information for this little event too.

Beyond Thursday, pretty quiet.  A new upper level trough develops offshore Saturday through Monday.  There are some deep surface lows that linger way out over the Pacific, but they aren't really going anywhere in a hurry, so they aren't a high wind threat for us…Mark Nelsen


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