Late Evening Thoughts

January 10, 2011

Not any huge change in my thinking this evening, but a few minor changes:

1.  Cold air is sure here!  KPTV Tower temps at 1,900′ down below 25 degrees right now, already a good 5 degrees colder than the WRF-GFS sounding said it would be.  And very dry air!  Dewpoints in the teens across the Metro area right now.

2.  Precipitation looks to arrive AFTER the evening commute, plus it’s going to be very light through 10pm or so.  That doesn’t help with evaporational cooling, but models want to keep us right at freezing until midnight or so.  I do notice our 4km RPM is colder than our 12km.  That’s probably better

3.  No snow; I eliminated all that wording out of my forecasts around 8pm.

4.  The change from tomorrow evening to Wednesday morning’s commute will be remarkable…32 to 50 degrees in 12 hours!

Chief Meteorologist Mark Nelsen

Ice/Snow Update: 2pm

January 10, 2011

Here is a synopsis (very brief) of what I think will happen the next 36 hours.  I sent this note to the newsroom. 

Sorry about the bold formatting; a bit hard to read.

Not much happening between now and tomorrow afternoon.  Just colder and windy as the east wind starts ramping up out of the Gorge…

Here are the main points: 
1.      It’s looking less and less like a “storm” and more like a 
few hours of freezing rain tomorrow night.  
2.      Forget about snow…it appears far more likely we’ll start 
with ice pellets or freezing rain.
3.      It’s going to warm up very quickly Wednesday morning.  
Then many days of very warm rain follow. 
TONIGHT:  Mostly clear, windy, colder…25-30
TUESDAY:  Clouding up, colder…36
TUESDAY EVENING (probably AFTER commute): Areas of light freezing rain develop
could be spotty the first few hours, could mix with snow or ice pellets too.
TUESDAY OVERNIGHT:  Areas of freezing rain, this should be the “slipperiest” time.  
Temps hover around freezing.
WEDNESDAY AM:  Leftover icy spots, but IT MIGHT NOT BE A BIG ISSUE?  We’ll see.
WEDNESDAY MIDDAY-PM:  Warm, windy, rainy…high near 50!
THURSDAY-SUNDAY:  Rain at times…highs near 50 each day
Chief Meteorologist Mark Nelsen

Forecast Catastrophe Update: Monday Morning

January 10, 2011

Cold and drier east wind is pouring through the Gorge this morning, nicely shown by the “new” Vista House wind sensor…more on that at the end of the post.  Nice that at least one thing can work out forecast-wise.  The sand box is closed because there is hardly anything to argue about anymore…we’re going to have a brief wintry precipitation event tomorrow night, then it’s on to a very warm and wet pattern through the weekend.

I almost started laughing while looking at the models for the next 48 hours yesterday evening, then I think I actually did this morning as things look EVEN WORSE if you want a big winter weather event here.  Do you realize that in 4 days we’ve gone from a surface low tracking south of Portland and a possible massive snow/ice storm to now a “normal” low moving onto NORTHERN Vancouver Island for Wednesday?

I tried to look at the maps this morning as if I had no pre-conceived notion of what might occur in the next 72 hours.  If you look at it that way, you get a brief period of freezing rain or sleet tomorrow evening/night with no snow.  So when I get in to work early this afternoon I’m probably headed that direction.  With a low pressure system so far north, our region gets flooded in warm air quickly overnight tomorrow night, mainly above the surface.  Models are still holding off a surface arrival of southerly wind until at least 4am Wednesday, so anything that does fall through most of the night should be freezing rain.  It’s just too warm above for snow.  Plus, precipitation may start rather slowly, which is never that great for evaporational cooling.

Crown Point Wind Sensor

This has been a little pet project of mine since around Labor Day.  I’ve always thought there should be a wind gauge up at Vista House, and apparently there has been in the past.  But they get destroyed by the bad ice storms.  The opportunity came up to try out there since I replaced the Corbett Elementary School sensor Vantage Pro with a Vantage Pro2.  The process has been very slow.  The Oregon State Parks people have been great to work with as well.  I suggested we try something temporary to see how it goes this winter.  It has to be out of there the first week of March.  Link is below:

Here’s what I did:

-No one is going to be drilling into a historic structure to put up a wind gauge for weather geeks!  I assumed that from the beginning.  And nothing can be accessible to the public or it’ll get vandalized.

– I poured 3 bags of concrete into a box (120lbs!), with a 2″ metal mailbox post embedded.  The Vantage Pro (old model) wind cups are mounted about 6 feet up on the pole.  We dragged that block up to the “catwalk” on Vista House last Friday.  My back was sore Friday afternoon.

– It’s a wireless unit, and those of you with the VP know that the range of the older ones is quite weak.  In fact it’s barely making it over the top of the concrete wall, then down into the basement through one of those skylights in the concrete.  Luckily there is DSL in there for the security cams and friends of the Vista House.  I took an old computer of mine and loaded up WeatherLink that outputs to CWOP.  It’s set to reboot when the power goes out…happens a lot out here.

– The first 2 days the signal was so weak that it hardly worked at all, but then I notice last night it started working much better for some reason.  Something to do with the colder temps???  I have no idea.   Either way, radio signals obviously don’t like to go through concrete.

– If the sensor survives okay, then this summer the Parks people MAY spring for a new VP2, which would have no transmission issues…they can transmit much farther.

– I think it’s a good setup (for almost free).  If I put in a new system with those folks, a destroyed wind gauge only costs about $110 to replace.  So maybe every other year one will break?  We’ll find out.

Chief Meteorologist Mark Nelsen