Afternoon Thunderstorms

April 28, 2010

Nice thunderstorm moved through the SE part of Portland between 4:45 and 5:15pm.  Big downpour, hail, and 7 cloud to ground lightning strikes.  You can click on the picture to get a closer view.

What a headache in the long range!  More on that later…

10pm Update:  And now it’s time for the update.  Good times today with all the active convection.  That storm spit out all the lightning strikes and then promptly shut down.  The showers were just flying today…15-20 mph.  That means we quickly moved from rain to hail to sunshine.  Someone at the coffee shop told me she just loves this type of Spring weather instead of the long, gray, gloomy days…I agree. 

Tomorrow looks a bit quieter with shallower convection and a more stable atmosphere.  It seems to shut down quickly after 5pm too according to mesoscale models.  Friday should be dry with showers confined to the hills (upslope areas).

The forecast issues are Saturday and beyond.  Looks like warm advection and a weak system moving right over the top of a building ridge will be strong enough to spoil our Saturday morning…probably drippy, especially in the upslope areas.  The Corbett community is turning out for a day of service to work on the schools and school grounds (mainly outdoor work).  I’ll be participating in that and unfortunately I think it’ll be wet!  The weather should improve Saturday afternoon and all models point to much better weather on Sunday.

The big disagreement is still beyond Sunday.  The ECMWF was still going “basketballs to the wall” with a cold trough moving right down into the Pacific Northwest in the 12z run.   The 00z run comes out in an hour or so.  The 00z GFS has come slightly towards the ECMWF, showing another system brushing us Monday morning on it’s way southeast.  Not any cold air with it in that case.  We’ve decided to go with the most consistent ECMWF, thus the cool and wet forecast starting Monday.  The annoying thing is that the GFS has been almost as consistent showing general ridging over us Sunday through Wednesday.  But with the 00z chinks in the armor of the GFS (Monday showers), I feel better now about staying with the ECMWF.

Chief Meteorologist Mark Nelsen