Cold Spring Night

March 20, 2007

SnapshotA quick drop in dewpoints this afternoon along with temperatures holding steady heralded the arrival of a much cooler airmass into the Northwest.  A nice little line of showers brought hail to them Portland metro area in the early afternoon too.  I noticed the temp even at the top of our transmission tower (1800′) didn’t dip much below 40 degrees, so any snow mixed in was short-lived.  But a cool and breezy day in general.
Very weak ridging develops over us the next 3 days, cutting off most of the rainfall.  But we’ll be right on the edge, with wet days in Seattle and guaranteed dry in Eugene.  Great…tough forecasting coming up again.  Spring IS the toughest forecast season west of the Cascades in my opinion.
One trend I see in the 00z GFS and 00z GEM is cold troughing for next week.  Just in time for Oregon’s spring break it appears that we’ll see a cold & showery weather pattern…Mark

Rain Returns

March 19, 2007

SnapshotI hadn’t really paid too close attention to the rainfall this month until tonight.  Wow, we were having a relatively dry March so far…until this evening.  Looks like PDX picked up over .50".  I was fortunate to spend 4-5 days at home working in the yard during the mild dry days lately too, so that took care of the last of the winter blues for me.  Of course that’s good since officially the astronomical spring begins tomorrow evening.  A chilly airmass moves inland tomorrow, dropping snow down to 2000′ by evening in the foothills.  Normally, during late March, this pattern would produce heavy downpours, hail, and possible thunderstorms.  But all model info says the airmass will not be very unstable tomorrow.  Lifted Indexes are too high and CAPE values aren’t very impressive either.  I dried out the forecast for Wednesday-Friday due to weak ridging developing with warmer temps by Friday.  Unfortunately the 00z GFS has the Thursday system clipping us, so hopefully that will correct itself in future runs…Mark

Comments Open

March 15, 2007

The blog is being monitored again, so go ahead and start discussing weather…Mark

Wet Weekend & Vacation Time

March 9, 2007

Snapshot_34Well, winter must finally be over because it’s time to take a week off.  I pushed it off a bit later this year after last year’s snowfall in early March while I was on vacation.  Won’t make that mistake again, especially after the snowstorm in January.  In fact the weather looks somewhat non-eventful the next week or so.  Just a very wet Pineapple Express aimed at Washington this weekend with Oregon on the southern fringes before the cold front finally sags south over us Sunday night and early Monday.  Tough call on forecast temps Sunday.  If the rain completely stops here through early Sunday afternoon, we could easily hit 65 degrees or so.  I’m confident that Olympia will be rainy all day and 55 degrees Sunday, and Eugene may hit 65-70 with partly sunny skies and a breezy south wind, but we’ll be right in the middle here.  After that some sort of ridging arrives midweek.  The GFS has been flatter than the ECMWF with that ridging.  If the ECMWF is correct, we may go above 70 degrees by Thursday, if the GFS is correct, maybe not above 65 before next weekend.
Since there will be no one here to watch the blog comments and the weather is somewhat slow, I’m turning off comments until at least next Wednesday, when I’ll have access to a computer again.  So everyone take a break and do something else for a few days.  Or, notice that you can go back and read 15 months worth of posts if you’re really bored…over to the right…Mark

Mid-March Weather Slowdown

March 8, 2007

Wow…only 9 comments in 24 hours!  Hard to believe that a cold spell or near-miss snowfall can bring in 800 posts in one day.  Must be slow weather and sure enough…it is!  Wavy looking front offshore looks pretty weak.  I sure didn’t expect the radar to be dry at 11pm.  00z models are insistent on pushing rainfall inland before daybreak so let’s plan on a wet morning drive.  Another system arrives midday Saturday and develops into a steady stream of rainfall aimed at Washington late Saturday through early Monday.  At some point the band of rain lifts north…possibly during the daytime Sunday. If so, our temps in the metro area would easily jump into the 60’s with a very warm airmass overhead.  Then the whole thing drops down through Oregon Monday and early Tuesday.
Long range models are now in a bit more agreement on some sort of warm ridging beginning Sunday.  Amplitude of the ridge will determine whether we get a sharp thermal trough and warm east winds (70 degrees or higher?) or just flat surface gradients for temps in the 60’s.  But that’s 7 days away, so LOTS could change before then…Mark

March Weather

March 7, 2007

Spring is a season of changing weather, from warm to cold and back again.  And that’s how the long range maps look.  After a warm ridge Sunday-Tuesday, now we have a much cooler atmosphere overhead …the Passes are well frozen this evening.  Warmer southwesterly flow returns Friday-Monday with freezing levels climbing up to 9,000′.  Then a cold trough drops through the middle of next week.  Now the 00z GFS has jumped onto the Canadian bandwagon of strong ridging following that as we head into the St. Patrick’s Day weekend.  Maybe our first 70 degree weather?  We’ll see, but enjoy the changes.  For the next 7 days it still means quite a bit of rain…Mark

Slow Weather, but Warm Night

March 6, 2007

Snapshot_33A very nice 2nd taste of Spring today.  Highs between 65 and 70 degrees were common across the northwest part of Oregon and southwest part of Washington.  The 65 at the Portland Airport occurred despite a continuing easterly wind.  As you see to the left, 2 years ago a regime of easterly flow brought us temperatures in the low-mid 70’s this time of year.  I clearly remember the steady easterly wind for several days.  This is the time of hte year where an easterly wind changes to a warmer wind instead of producing cooler temps.  The warm upper-level ridge is slipping off to the east this evening, allowing a weak front to move onshore.  Models are very slow bringing rain inland tonight;  most likely it won’t arrive until closer to daybreak.  I also notice a trend in the 3-4 day forecast is for no huge amounts of rainfall, just lots of onshore flow bringing cloud cover and light rain at times.
Off/on rainy weather will continue for at least the next 7 days.  Some models are hinting at ridging returning the middle of next week, but thats a long way off!  Mark