Is That Really an 80 Degree Day in the Forecast?

April 17, 2013

The short answer is yes, here’s the longer answer…

We’re increasingly confident that the early-middle part of next week will be quite warm for several reasons.  Here’s our 7 Day forecast as of Wednesday evening:

7 Day

Why?

Models today have suddenly come into great agreement for the 4-8 day period (Sunday through next Thursday).  The past few days they have been all over the place beyond Sunday; this is common when models are struggling with an upcoming pattern change.  But now they’ve settled on the change.

That change is strong offshore surface flow (an east wind event) from Monday through Wednesday next week, plus 850mb temps peaking out around +11 to +17 next Wednesday, depending on the model.  The 12z ECMWF was the warmest with the +17.    For comparison, in the 18 Aprils from 1992 to 2009, only 3 days saw a +17 degree or warmer temp.  All three of those days were 85-90 degrees.  But, that ECMWF temp was an outlier.  Regardless, a +15 degree temp with easterly flow and 100% sunshine will push us into the 80-85 degree range this time of year.

10pm UpdateMaybe I should have checked the blog & high temps from April 22/23rd just one year ago!  Exact same situation pushed us to 82 degrees two days in a row!  https://fox12weather.wordpress.com/2012/04/20/warm-weekend-is-here/

Continuing on…

Here are two of the usual ensemble charts I show, compare them to charts from just two days ago; far more agreement:

12z ECMWF…

tseries_850t_000-360_Portland

12z GFS…

tseries_850t_000-384_Portland

And here are the ensemble 500 mb anomaly maps for next Wednesday from the ECMWF, GFS, and GEM (Canadian model).  Notice they all show ridging right along the West Coast:

ecmwf12z

gfs12z

can12z

Almost 3 weeks ago we hit 77 two days in a row (remember Easter Weekend?), upper 70s isn’t a huge deal in late April.  Most records are in the 80s in those last 10 days of the month.  Next Wednesday’s record high is 79 at PDX.

Chief Meteorologist Mark Nelsen