Hottest Day Tomorrow

September 6, 2011

Here’s a nice image from the TERRA satellite, taken about 2pm today.  You can see a large amount of smoke from the fire down near Santiam Pass.  Not quite as much smoke, but still yucky from the ground, from 3 other fires burning to the NW and NE of Mt. Jefferson and north of Mt. Hood.  Tomorrow all that smoke heads west over the western valleys of Oregon.  Combine that with what should be a far more active fire day and we should see a very smoky afternoon from Longview down to Eugene, including here in Portland.  It’ll be very interesting if tomorrow’s conditions produce a big run and/or large plume over any of the fires.  We haven’t seen that since Saturday.

Not much change to my thinking for the next 24 hours.  Easterly wind is just beginning over the Cascades.  I see temps have risen and humidity has dropped the past few hours at the 3 temporary weather sensors put in place around the Dollar Lake Fire.  The sensors are labelled IRAWS.  No wind yet at Crown Point, but with pressure gradient starting to turn easterly it’ll arrive soon.

Tomorrow’s east wind doesn’t look strong here in the metro area or in the Gorge for that matter, but the 4/3km WRF-GFS shows it making it into the east side only.  This could be one of the “perfect” situations where we get the maximum effect of the downslope warming wind, but not enough wind to limit heating at PDX like we saw last Saturday.  So I raised our forecast from 94 to 96.  I like to be within 3 degrees, so I think it’s very unlikely we’ll go above 99 or stay below 93.  A little window into my forecasting thinking.

Once again, it’s nice that this time of year temps drop very quickly in the evening.  McMinnville was 47 this morning, but 95 this afternoon!  That’s a 48 degree temperature rise.  And as of 10pm in the MAC it’s already dropped 25 degrees since the afternoon high.

Chief Meteorologist Mark Nelsen