Wednesday Soaking?

July 17, 2007

SnapshotNice little picture isn’t it?  It’s called a Haboob  and it’s a wall of dusty air sweeping across the Arizona Desert this afternoon.
That’s obviously not a problem for us the next 24 hours.  We’ve got a nice shortwave coming up from the south tonight, swinging around a large upper-level low offshore.  1.30" precipitable water combined with a 11,000′ freezing level sure seems to give us the possibility of significant rainfall.  I notice the rapid cooling of cloud tops to our south this evening coincides with significant radar echoes rapidly approaching from the south too.
Our model here (RPM), which is almost always too wet, shows a large chunk of Northwest Oregon receiving a solid inch of rain or more.  IF steady rain does develop as expected, with this warm of an airmass and good lifting that is not unreasonable.  As for thunderstorms…it’s going to be tough to get anything other than a flash or rumble with such solid cloud cover through the afternoon.
Thursday is definitely an "in-between" day with more sunbreaks.  Then another system offshore takes a swipe at us Friday, but this one is headed mainly for Washington.
Weekend models are in disagreement.  This is part of the big picture models are having trouble with.  Will the upper level low stay just offshore the next 7-10 days?  And how far offshore?  A slight movement farther to the west gives us 80 degree weather.  If it moves closer (like right now), we get rainy and cool weather.  Sure looks interesting, annoying to forecast for, and unusual for the latter half of July…Mark