Warm Day and Cold Ahead

March 29, 2007

SnapshotA very nice day today…apparently even my "wild" forecast of 66 last night for this afternoon was too conservative.  I notice the 850mb. temp at Salem this afternoon was +10 C.  That’s 2-3 degrees warmer than models had forecast.  According to the "Mark Nelsen 850mb chart" for March, a +10 on average will produce a high near 66.  With a good easterly flow, up to 72 or 73.  So we could have been even warmer!  We did have a nice east wind through the Gorge and over the Cascades, but barely enough to make it into the city.  Looks like the east wind just touched the airport this evening, but blew at Troutdale all day.
A nice combination of southern stream energy and a cold northern stream system offshore.  It’s moving pretty quickly so I’m a bit worried that we could see completely cloudy skies with light showers before the more widespread light rain arrives in the evening tomorrow.  Tough call.
Weekend forecast continues to be a challenge.  The big picture shows a deep and cold upper-level trough developing off the NW coastline Saturday and Sunday.  If you look at the 3 day forecasts of 500mb. vorticity, you’ll notice energy drops into this trough from the Arctic Ocean and northern Alaska!  If it was winter we’d be talking possibly snow with the showers Sunday.  Since it’ll be April 1st and the showers don’t look very heavy, I doubt we will see sticking snow below 2000′.  A cold Sunday for sure…hopefully the payoff Easter Sunday (the following week) will be a warm and sunny day.  One can always hope right?  Mark