102 at PDX Saturday…Hottest Day in 3 Years!

August 4, 2012


We had a perfect setup to maximize heating over the Western Valleys today.  A very warm air mass above, cloudless skies, and moderate/strong offshore flow.  Just enough east wind to make it to PDX and VUO this afternoon, but not so much that it held the temp down.  Note the difference from Portland to Troutdale.  Gusty east wind at Troutdale all day and the high only made it to 97.

We not only broke the daily record of 100 degrees, but today was the first 100 degree day in Portland since late July 2009.  Remember the heat wave with back to back 106 degree days?  Kind of hard to forget.

If you hate really hot weather, there is good news.  We lose the offshore flow overnight and tomorrow morning, but the atmosphere overhead will remain just about as warm tomorrow afternoon.  Take away the offshore flow and low-mid 90s are the general target for a high temperature here west of the Cascades.  The coastline will be much cooler with a southerly surge of cool air moving north overnight.  Cooler still on Monday with slightly more onshore flow and a slightly cooler atmosphere.

Of more interest is the chance for thunderstorms tomorrow night or Monday morning.  All models show a weak upper-level disturbance swinging north right over us sometime after midnight.  But not all models generate thunderstorms.  Our RPM (at least the 12z & 18z so far) shows just cloud cover but no storms/showers.  The WRF-GFS has been hinting at some action closer to daybreak Monday.  The pattern looks good to me with plenty of moisture higher up in the atmosphere and the favored SE flow plus a hot air mass.

I don’t see any dramatic cooling (below 85 degree highs) until Wednesday when an upper-level trough swings by, bringing us a major push of Pacific air.   The long-range picture seems to be for the 4-Corners High to remain near its normal summertime position near…the 4 corners region in the desert southwest.  This means average or above average temperatures are likely through at least the first two weeks of August.

Chief Meteorologist Mark Nelsen