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Monday, June 01, 2009
Wednesday, July 30, 2008
Vacation Time Again
The forecast worked out perfectly again today. Morning clouds to afternoon sunshine. You know it's a chilly airmass when a sunny afternoon only produces a high of 72 at PDX on July 30th!
A nice plume of moisture is getting organized to our west this evening. It's a combination of subtropical moisture streaming across the Pacific and a system dropping south out of Alaska that gives us a rain threat late tomorrow night and Friday morning. Once again, it won't give us much rain inland...just like Tuesday.
The trough swinging inland over the Northwest Friday-Saturday is showing signs of lingering through the rest of the weekend as well. The always-pessimistic NAM has 500mb heights down around 567 dm. That's similar to a cold June upper-level low. I've discounted that since the ECMWF and GFS are not as deep. And speaking of ignoring some models...you may notice the 7 day forecast doesn't match the big warm up forecast on the ECMWF and GFS models. They both say we'll be 90-96 Tuesday and Wednesday. Maybe as warm as 85-90 on Monday as well. When I saw that today, I immediately assumed that the familiar pattern of models backing off on warm spells would continue. Sure enough, I see the 00z is already cooler for Monday. But Tuesday and Wednesday are still forecast to be scorchers. I am breathlessly awaiting the 00z ECMWF. Well, actually I'm still breathing, but you know what I mean.
On the home front, I had a face to face encounter with Bambi in my garden last night around 12:45am. He/she was munching on the carrots looking very contented. My kids accidentally left the gate open. Hmmm, 2 apple trees appear a little stripped...the battle continues...
I'll be off the next two days in exchange for working an 8 day stretch when I return from vacation late next week. So no new posts until at least next Friday, the 8th. Mark Nelsen
Tuesday, July 29, 2008
A Big Rain Day
At least it was a rainy day by late July standards. I mentioned during the 10pm broadcast that only 4 times in the last 20 years have we had more than .10" during the last 7 days of the month. We didn't do that today, and I don't think we will Friday. However, we seem to be stuck in a troughy pattern through the extended period.
I notice the 00z GFS has no temps above +12 at 850mb through the next two weeks. It is the coldest of the ECMWF, GEM and GFS models (the main long range models I look at), so it may be forecasting a bit cool.
Not much else to talk about, so I'll leave it at that for tonight...we're just about to the dog days of summer. Mark Nelsen
Monday, July 28, 2008
Back to Work & Bambi Returns
It's a brand new week and we actually have a cold front on the way for tomorrow. What could be more exciting at the end of July? A nice outbreak of thunderstorms...but apparently we got too much of that early this summer. We'll have to settle for an afternoon cold front passage.
Not a ton of rain with the approaching front. No model shows much more than .10" in the lowest elevations west of the Cascades. Of course we should see a bit more in the mountains and foothills.
This is a one-shot deal for rain. Brief ridging later Wednesday and Thursday returns us to warmer temps and more sun. Friday and early Saturday another trough swings through. We MAY see some showers with this as well. Models are all over the place with that one, but seem to be trending stronger.
GFS now looks "troughy" through the extended period. So I lowered 7 Day forecast temps quite a bit (from 4pm). ECMWF as of 12z wasn't quite as baggy looking and had more ridging. Hmmm, looks quite similar to last summer, but not so wet. And so far we've escaped excessive cloud cover west of the Cascades.
On the home front: after unloading the camping supplies yesterday evening (trip to Clear Lake), I left the gate open BUT the trailer was mostly blocking the entrance. Apparently a deer slipped in the 2-3 feet that were left open. Clever little guys aren't they? Not too much damage done in the one evening, but I'm guessing all his/her friends were waiting at the fence this evening. Mark Nelsen
Friday, July 18, 2008
Volcano Dust and Vacation Time
Well, it appears that the ash cloud from Okmok Volcano has arrived over the Pacific Northwest. The volcano is just west of Dutch Harbor, Alaska (in the Aleutian Islands). It erupted violently last Saturday and Sunday, spewing large amounts of ash and sulfur dioxide into the upper atmosphere (around 50,000'). You can read all about it on the Alaska Volcano Observatory website. What we see overhead is a very thin veil of ash moving in from the west-southwest, but a long ways up in the atmosphere...above 30,000'. The image here is from NOAA. It shows the sulfur dioxide cloud position early Thursday afternoon. Of course that would contain some ash as well. It sure produced a colorful sunset!
As for weather, it's not exactly life threatening, but tracking the depth of the marine layer is a very annoying forecast problem. I was off by 5 degrees on the forecast high today due to a deeper-than-expected marine layer. It looks thinner the next two days on the models, especially Sunday, that's why I've gone with warmer temps.
The weather pattern stays GENERALLY the same the next 7-10 days. A big ridge centered over the Rockies and weak troughs occasionally trying to get close to the West Coast, or at least tracking by to the north through Southern Canada. Of course this pattern gives us a marine push from time to time, keeping temps in check. No hot weather in sight, no rain, and probably no thunder even east of the Cascades. Basically real pleasant summer weather...that's good because I'll be on vacation all next week. I'll only post if the weather is interesting. Otherwise I'll be back on the 28th...Mark Nelsen
Thursday, July 17, 2008
A Slow Thursday Evening
Well, we have a moderate onshore flow, no heat wave in sight, and no rain showing up on the maps either. Add to that no good chance for thunderstorms in the near future and you get a very slow weather evening. Even the fire situation has improved with only 4 major fires ongoing in Oregon and Washington.
This morning's low cloud cover inland was limited to mainly east of I-5 north of and Oregon City to Sandy line. It should be a different story Friday morning, I see Longview had clouded in by 10pm and temps are running a few degrees cooler this evening too. I still don't think it'll be a marine layer up to 3,000' which can take most of the day to evaporate. So I'm planning on a noon breakout at the latest here in the metro area. The westside may still have limited cloud cover.
Saturday through Monday: Rising heights in the upper atmosphere should keep the marine layer lower and closer to the Coast. Temps should make it into the 80s as a result.
Tuesday and beyond: A bit lower heights and troughiness offshore spell another period of morning clouds/afternoon sun. It doesn't look like last summer where a sharp trough lingers near the West Coast...for now. Mark Nelsen
Tuesday, July 15, 2008
A Late Baseball Night
Apparently it's going to be a very late night tonight on FOX12. The 15th inning of the All Star Game is just beginning at 10:20pm. We are committed to 90 minutes of news following the game...do the math and one realizes that we'll probably be on the air until well after midnight (at least). SO...plenty of time to post on the blog don't you think?
Today was a big surprise with little to no onshore push yesterday evening. Temperatures were cooler in the Willamette Valley, but we ended up rising two degrees here at PDX. That means we've now had 5 days at/above 90 in the first half of July. That meets our 90 degree quota for the month. It's possible we have some 90 degree weather coming up at the beginning of next week, so it's looking like it won't go down as a cool summer for sure. As for whether we remember Summer 2008 as a hot one? Only the next 4-6 weeks will tell.
Finally, a significant onshore push is in progress tonight. Last night there was no cooling/gusty west wind at Corvallis or McMinnville. We have that tonight. At 10pm it was running 14 degrees cooler at CVO than last night at this time. Kelso is significantly cooler as well. Even so, I'm thinking my 77 degree forecast high for PDX may be a bit low. I'm thinking 80 is far more likely. Okay, we'll play it this way...if the game goes to a 16th inning, then I'll raise tomorrow's forecast high to 80. If not, then we leave it at 77. Pretty scientific eh? Mark Nelsen
A minor maintenance note. Some folks have complained that their posts don't show up after posting. Remember that you HAVE to hit "refresh" to have the comment show up (most of the time).
Friday, July 11, 2008
A Perfect July Weekend
For the first time since Monday morning, the temperature at Brookings this evening has dropped below 70 degrees! Take a look at the numbers on the image. This would be amazing in Portland, let alone right beside a cold Pacific Ocean. It's interesting that when we look back at big heatwaves in Oregon, this week wouldn't even show up as one. Except in Brookings it'll be remembered as the hottest week ever!
For this upcoming weekend, it appears to be perfect weather for outdoor activities near water. Temps near or above 90 both days, sunshine from sunrise to sunset, and low humidity.
Not much else to say except we'll be a bit more "troughy" by the middle of next week. Models have been all over the place for location, depth, and timing of a trough nearby. A general trend I THINK I'm seeing is the tendency for models to continue backing off on intensity. So over the last few days the 850mb temp forecast for much of next week keeps rising. Remember that two nights ago I had some high temps quite close to 70 degrees. Now I don't see it getting much below 80 degrees for highs. No sign of rain either...Mark Nelsen
Thursday, July 10, 2008
Wednesday, July 09, 2008
90 Degree Day
It was a very warm...okay hot...day today. Looks like PDX was the coolest spot in the Willamette Valley. Salem was 94 and Eugene 96.
Hard to believe, but Brookings once again went past century mark, jumping to 102 degrees late this afternoon. It was 85 there this morning. Now Steve Pierce JUST sent me an email (one of only 400-600 since January), pointing out the AG station just south of Brookings was 64 at 9:15pm with a light southwest wind, then the north breeze picked up...15 minutes later it was 88 degrees. Now that's a thin marine layer! Thanks Steve.
We have a well-advertised marine push in progress right now. It's triggered by an upper level trough passing by to the north. Now this one is a "northwesterly" marine push, which often doesn't give us much low cloud cover. Notice that dewpoints have dropped somewhat dramatically in spots. I see the dewpoint here at the station has dropped well down into the 40s. This should give us a cooler night tonight and tomorrow night. Even with the cooler airmass Thursday, sunshine plus dry air should push temps back up near 80 degrees.
As I mentioned last night, upper level ridging bounces back Friday-Sunday. 500mb heights get up close to 590 dm later Saturday, which should push temps back into the lower 90s again.
Long-range maps still look a bit "troughy" starting Monday, but each model is a bit different. Of course more marine influence is likely.
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