Hot Weekend Ahead; But Not Really A Heat Wave

June 4, 2015

5pm Thursday…

All signs point to our warmest weather (okay, hottest weather) of the season so far this weekend.  Just a couple of days ago models were a bit warmer, forecasting highs well into the 90s or even closer to 100 (the GFS)  in the Portland metro area.  But now they’ve settled on a more reasonable period of briefly hot temperatures Saturday and Sunday right around 90, plus or minus a couple of degrees.

I lowered our forecast high temps a bit today, and then noticed the NWS did as well…for two reasons:

1. This isn’t the heat wave pattern with easterly/offshore flow.  We never totally lose the west wind in the Gorge and there is no thermal low pressure area west of the Cascades.  As a result we continue weak onshore flow through the weekend and early next week.

2. 850mb temps peak out at +18 to +20 degrees over Salem.  Previous cases in this pattern have high temps right around 90.

IF this exact same atmosphere was overhead and we had good easterly flow, temperatures would soar into the 95-99 degree range.  But that’s not going to happen.

To consider it a real heat wave in our area I would expect 3 days 90 or above generally.  And no records will fall at PDX.  The record highs are 98, 93, 94 for Saturday, Sunday, Monday.

So enjoy the hot weather if you are one of those people.  River levels are lower than normal and they are running warmer than last year as well.  The Columbia River is already up to 64 degrees, pretty warm for the first week of June!

MarkRiverLevels_ColumbiaOnly

Looking ahead through next week and beyond, we have definitely entered a stable summer-like pattern for awhile.  Both the GFS and ECMWF have NO precipitation for the next 10 days…Continue watering!

ecmwf_precip_10days

gfs_precip_10days

By the way, May continued the trend of warm months in the Pacific Northwest.  Only 1 month out of the past 12 has been below average…that was November

TempDeviation_WSI_May

Chief Meteorologist Mark Nelsen