Warmest So Far Wednesday: 90 Likely in Portland

May 13, 2014

11pm Tuesday…

Okay, I’ll admit it.  A little warmer than I’d like (for May) late this afternoon/evening.  We hit the mid 80s in most of the metro area today, buoyed by the offshore wind flow.  Even most of the coastline was between 75-80 degrees.

MarkWarm_PortlandRecords

We didn’t hit the record, which is 92 degrees.  But tomorrow’s 88 degree record is definitely at risk.  I am forecasting a high of 91 tomorrow; in reality I wouldn’t be surprised if it was as low as 88 or as high as 93.  It should be in that range with cloudless skies, offshore flow, and an 850mb temp between 18-19 degrees celsius over Salem.  That means in the open atmosphere, the temperature around 5,000′ should be around 66-67 degrees.  We’ll see how that plays out tomorrow.  Today it was +15.6 degrees over Salem around 5pm.  The soundings are taken twice a day by balloon…old style!

So assuming we hit 90 tomorrow, how rare is that in May?  Well we haven’t done it for the past 5 Mays, although we have hit 88-89 at times:

MarkHeatwaveStudio_90DegreeTemps_May

The last time was during a heat wave in 2008.

Temperatures will cool dramatically Friday through Monday.  In fact you can see the below average temperatures up at 5,000′ (850mb) on the ensemble chart from the 12z ECMWF.  You may also notice one other thing; temperatures go back above average after next Monday.  It appears mild weather is going to stick around through most of the 2nd half of the month.

tseries_850t_000-360_Portland

The new 00z GFS chart is similar, showing the 2nd half of May looking more like mid June:

tseries_850t_000-384_Portland

So I’m planting my tomatoes and squash…looks like a good chance they can get settled in with the mild weather and handle a (hopefully) brief cool spell in June.  Around 2010-2011 I couldn’t do that until around the 4th of July!

Chief Meteorologist Mark Nelsen