3rd 80 Degree Day Today: Chilly Midweek Ahead

May 7, 2012

We just barely squeaked out an 80 degree temp at PDX today, although most of the metro area was in the upper 70s.  A beautiful summer-like day that started chilly and ended warm.

Speaking of chilly, you can see a narrow cold front approaching from the west…it’ll be into Northwest Oregon by this time tomorrow evening and then into Idaho by Wednesday.  I see 3 main effects:

1. Much cooler temps, first a switch to onshore flow tomorrow west of the Cascades, then the much cooler atmosphere arrives all areas Wednesday for about a 20 degree drop in high temps.

2. More cloud cover, but little or no rain.  The brunt of a cold upper level trough is heading to our north, leaving us with the very weak southern portion.  If we get sprinkles, it’ll probably be Wednesday afternoon as the trough passes overhead.

3. Huge wind far eastern Gorge and eastern half of Oregon and Washington.  Tremendous westerly pressure gradient on Wednesday with the cold air advecting eastward.  If you’re a windsurfer, it looks like a raging day from The Dalles east to Boardman.  If you’re driving EAST on I-84, you should save a bit on gas.  If you will be driving WEST from Pendleton to Portland in a Hummer with a fully loaded roof rack plus 30 ft. camping trailer behind?  I weep for you and your gas bill…

Looking farther ahead, models are amazingly consistent on upper-level ridging returning for a very warm Mother’s Day Weekend…check out the 12z GFS ensemble 850mb chart:

Note the cold drop to around -4 at midweek then a rise to around +16 by Sunday!  Then a drop to -5 again by the following Tuesday.  I also see that -5 is at the extreme lower end.  The ensemble mean for the next 7-10 days is above average.  We are busting out of the two year in a row “May Cold Curse” in 2012.  Here’s a graphic I put together showing 70 degree days the past few years in May (the whole month) along with our forecast for the next 7 days. 

A week from now we should already be ahead of last May.  Plus, the past two Mays we’ve seen no 80 degree temps.  We may have 4 under our belt before the 15th this year.  Quite a change…as a result, the Nelsen pool is going up tomorrow.  Two years ago I didn’t put it up until late June.

Chief Meteorologist Mark Nelsen