Location Is Everything

March 23, 2006

If you were looking for a warm day today, you had to be in the right spots.  Specifically, we had lots of very warm air overhead, but it only "mixed down" in a few areas.  At 1,800′ on top of our transmission tower in the West Hills, the temperature sat at 62 degrees this afternoon.  That usually would equate to 68-70 down in the city.  East winds out of the Gorge brought those windy spots up into the 60-62 degree range.  But the real warm areas were the towns where a light easterly wind off the Cascades prevailed.  Battleground, Hockinson, Sandy, Estacada, Brightwood.  As you can see in the map below, 65-68 was common in those areas.  IF a southerly wind had developed on schedule (see yesterday’s blog), and we had just 2 hours of hazy sunshine instead of solid cloud cover, I think most of us would have seen 70 degrees today around the metro area.  Notice the calm wind spots (Hillsboro, McMinnville, Aurora) stayed below 60.Snapshot_5

Tonight’s cold front is VERY slowly moving inland, evidenced by the cooler Coastal temps, but there’s another wave moving north along it which will prolong/renew the rainband later tonight and into the morning hours.  One more wave comes through Friday night.

A cool & showery weekend then in store since we will be in the chilly post-frontal airmass.  A brief break Monday, then back to more wet stuff next week.  GFS keeps trying for a drier-warmer pattern, but notice it keeps getting put off a day?  Kind of like arctic air in wintertime eh?

By the way, folks from McMinnville can relax.  For a couple years we’ve been getting nasty emails from some of you since our radar maps have displayed it as Mcminnville.  Apparently capitalizing the 2nd "M" is a civic pride issue.  On the map to the right we minimize the "C" to keep everyone happy as well.  Either way it’s fixed now with a software upgrade…so now there’s no need to throw objects at your TV in anger (some said they actually did that!).

First Mistake of Spring

March 22, 2006

What was I thinking???

Last night I made what is probably the 2nd worst mistake a meteorologist can make here in the Northwest in springtime.  I jumped a little too quickly on long range models showing a nice warmup early next week, making quite a big deal out of mid 60’s or even close to 70 Monday-Tuesday.  So everyone’s hopes were up…

Of course the next few runs of the ECMWF & GFS decided to bring a shortwave trough through by late Monday and keep it cool/showery Tuesday-Wednesday instead.   So a big (and annoying) change to the 7 Day forecast followed this evening.

By the way, the worst mistake I could make in springtime is only slightly different.  Make the same promise for a weekend, and do it for several days before "revoking" the sunny forecast.

That said, ECMWF & GFS in the big picture have that wave early next week as just a temporary rut on the road to warmer weather and ridging developing over the Western USA.  So I COULD have made a big deal out of possible much warmer/dry weather later next week, but who wants to run headfirst into a brick wall twice?

Short term forecast is interesting as satellite imagery seems to confirm the forecast for tomorrow.  Nice wave moving north along the stalled frontal system that is just offshore.  That will keep it out there through tomorrow afternoon, then the whole mess pushes in by evening.  Considering we made it to 58 with solid cloud cover today, a 6 degree rise should be easy to achieve tomorrow.  IF by some chance we get partly cloudy or mostly sunny for more than 2 hours, we could easily jump to 68.  But I’m getting older and more conservative (in forecasting at least), so 64 still looks like a good high for PDX. 

Regardless of the amount of sunshine, it should really feel like spring around here tomorrow.   Plus I just bought some more bulbs for the garden today (you can never grow too many plants right?) so I’m in a "Springy" mood.  Time for some warmth!..Mark

On With Spring

March 21, 2006

Not much change in our visible weather overhead today or tomorrow.  A front moves inland, but really stalls right over us Wednesday.  Then as a deepening trough offshore develops, the wavy front (with it’s rain) is pulled back offshore for most of the day Thursday.   This is a classic spring setup that can bring us unexpectedly warm weather for just one day.  So my plan is to "expect it" instead of being surprised.  Always a good idea eh?

Then the whole trough moves inland Friday-Saturday, so it’s back to the usual cool showers and sunbreaks.

What I really notice on the maps as I look through the next 7-10 days is…well, April!  Obviously we are in the last 10 days of March now and it doesn’t take a brain surgeon to figure out April is just around the corner.  But forecast models show a general change to a slower-moving regime and much weak storms that is more typical of April.  What does that mean to you?  Not as much wind, warmer days (on average), and not all that much rain.  Instead of a front dropping .50" of rain, we get maybe just .20" or so.  Expect more regular 60 degree temperatures to arrive the beginning of next week.  I wouldn’t be surprised to see our first 70 degree temp before spring break is finished too.

Active Afternoon, Slower Weekend

March 17, 2006

Pretty busy afternoon with heavy showers popping up through the cold air above.  A few little "anvil-tops" moving through give us brief bursts of heavy rain and hail.  Only 1 lightning strike near the metro area so far this afternoon (as of 4:15pm), just west of Yacolt around 1:30pm.  As mentioned below though, we often see this sort of activity peak out around sunset or just before.  This is also the pattern where we tend to see heaviest showers east side of town.  Part of that is due to the airstream "feeling" the lifting of the Cascade foothills before it actually gets there.  So Battleground, Camas, Troutdale, Gresham, Sandy, Estacada areas often get dumped on by late afternoon in this setup.

With the loss of daytime heating, showers quickly collapse after sunset…there’s no good dynamics to keep them going after that time.   One more weak disturbance drops south through Western Washington Saturday afternoon, which will probably set off a few showers over the mountains, but most likely we are done with rain for a few days (finally!).

Looks like a new trough developing way out in the Gulf of Alaska will split with most energy curling south into California Monday.  We haven’t seen much of this pattern in the last few months.  Remember this was almost constant last winter (2004-2005), leading to very little rain here.

Another trough moves much closer to us midweek, which brings rain back into the forecast.

Even though we warm up a bit the next few days, I still don’t see anything that could get our temperature up to 65 or warmer.  Do you realize we haven’t even seen 60 yet in Portland this late winter/early Spring?  Strange.  I’m going to check out the record books and see if our first 60 degree temp has been this late in recent years.   Enjoy the weekend…Mark

Still Wet

March 15, 2006

Big upper-level trough is slowly edging towards the Pacific Northwest coastline tonight.  One wave went through this morning and a 2nd this evening.  The 3rd arrives for the morning commute.

Another cool & unstable airmass arrives by tomorrow evening.  I expect this should give us a showers/hailshowers/thunderstorms day for Friday.

Evening models are slightly warmer again for Friday and Saturday, so snow levels should remain above 1,500′.

What to do about the extended forecast?  That’s the question tonight.   Models are all over the place.  ECMWF continues to be the mildest and driest through early next week, but at least the 00z GFS has come around to drier.  So I’ve kept the forecast dry Sunday-Tuesday and thrown in rain for Wednesday.  That was based on the ECMWF.  I would say the big story long-range is a warmup to average or above-average temps.

Chilly March Continues

March 14, 2006

Pretty well-defined pattern the next 4 days.  The big picture shows a large trough of low pressure diving down into the Gulf of Alaska Wednesday.  It progresses east and is centered right over the Northwest by Friday afternoon.  One weak shortwave moves through tomorrow, the stronger one with colder air behind arrives Thursday. 

The ECMWF never lets 850mb temps get below -4 C.  But the 00z GFS & 00z ETA drop us to -8 by Friday night.  That’s cold enough to bring snow to 1000′ with regular precip, and lower IF we get heavy showers again.  We all know how dependent snow level is on precipitation intensity (remember last week?).  A forecast 500′ snow level can easily be snow on the beaches with heavy, sustained precip with no wind.  So I’ll be watching this pretty closely.  My gut feeling is it’ll be tough to get sticking snow below 1000′, but it’s definitely a possibility again.

After that, all models show a change to warmer late March weather (finally 60’s?) next week.  The main difference is that the 00z GFS & Canadian bring one last system through later Sunday or Monday, the ridging.  The ECMWF doesn’t move that system over us so the warmer/dry weather begins Sunday.  I went with that forecast as you can see from the 7 Day.  We should have a much better idea in another 2 model runs.

I’m trying to think positively, hoping that the cool March so far means we’ll get warmer than normal in April or May???  I suppose that’s better than the opposite (last year’s warm start, then 2 months of cool/wet).


He’s Back!

March 13, 2006

That would be me of course…Drew needed some time off after that exhausting week!  Sorry for the delay this evening, but vacation is slowly wearing off apparently.

Nice cold trough offshore this evening, several lightning strikes off of North Bend and Brookings, they will see some flashing down there tonight.

We are moving into the time of year (warm season) when inland lightning becomes more common than coastal or offshore lightning.  That’s because we start to get warmer (slightly) days while the atmosphere overhead is just as cold as wintertime.  That makes airmasses more unstable than just one month ago.  Of course once we get closer to May, the strong sunshine heats the lower atmosphere much better and then that instability brings the thunderstorms.

Either way Tuesday should be an active weather day assuming we get plenty of sunbreaks inbetween the showers.

Long term:  Models (00z Canadian, GFS, 12z ECMWF) are hinting at at least brief ridging the beginning of next week.  That would bring us our first 60 degree weather of the season!  A bit late, but not unheard of.  Usually by the 18th of March we have had a run of 60+ degree weather with maybe a 70 thrown in.  Not this year!