Cooler Today, Two More Summery Days

September 12, 2013

PLOT_Highs_Metro

Quite a change today…the marine air surged inland overnight, giving us low clouds and much cooler temps.  We dropped from 95 yesterday to 82 today.

Tomorrow the marine layer should be a little thinner, so I boosted the high temp a few degrees.

Saturday and Sunday are real interesting.  Offshore flow briefly develops Saturday afternoon and night.  That should push temps up to 90 or a little above with 850mb temps jumping up to +20 or so.  That will probably be our last 90 degree day of the season.  Then on Sunday a fast-moving upper level trough swings through with MUCH cooler air.   850mb temps go from +21 Sunday morning to +6 24 hours later!  Thus we’ll be going from summer heat to fall “chill” pretty quickly.  It should be invigorating!  You can see the dramatic drop in the 12z ECMWF ensemble chart:

tseries_850t_000-360_Portland

The rest of next week will be dominated by cooler than average weather and showers at times.   By the way, here are the 4 weekly ECMWF 500mb height ensemble maps from last nights’ run:

500za_week1_bg_NA

500za_week2_bg_NA

500za_week3_bg_NA

500za_week4_bg_NA

Chief Meteorologist Mark Nelsen