More Thunderstorms

July 10, 2009

A "near" Severe Thunderstorm This Afternoon over Detroit Lake

A "near" Severe Thunderstorm This Afternoon over Detroit Lake

A nice little snapshot of a briefly strong storm over Detroit Lake this afternoon shows how a nice sunny day can turn dangerous over a Cascade Lake.  At this point the cell appeared to peak out around 63 dBz or so.  Looks like about 10 cloud to ground lightning strikes within 15 minutes in the area.

Then about one hour later a storm briefly pulsed up around Molalla on it’s way north, producing 4-5 strikes close to town.

There is obviously still some mid-level instability out there this evening (10:30pm).  There have been 5 strikes in the last 15 minutes between Newport and Yachats.  That would be OVER a cold marine layer.  It must look neat to see the lightning strikes come punching down through the low clouds and drizzle.

Tomorrow looks very similar to today with the upper low remaining well offshore.  I don’t see any good trigger for widespread convection…very much like today.  I notice our RPM has almost no convection at all. 

One change in the lower atmosphere is that some marine air is flooding into the southern/central part of the Willamette Valley.  Models show some of this filtering into the north valley by morning.  Will it still make it to 90 tomorrow?  The push does look very shallow, and it is coming in from the southwest…notice Kelso never had a big push this evening?  So I left the temperature the same in the forecast, but I could easily see only 87 at PDX.

Tomorrow night could be fun as the upper low makes it’s move inland to our south.  Our RPM shows showers suddenly breaking out 8-11pm and continuing overnight in the southerly flow.   I also notice the big southwest low level surge of marine air doesn’t come in until around daybreak Sunday.  So it may be a warm and humid Saturday night with some thunderstorms around.

Next week looks very typical and boring summer weather, which means a great vacation week.  I have some “home time” and some camping planned in the Cascades, no  big extravaganzas.  I’ll be back Monday the 20th.  No posts until that time unless Drew or Rob get really inspired by the sunshine.

Chief Meteorologist – Mark Nelsen