I've been real busy today with a midday school visit in SW Portland and then a 2 hour visit to a PCC Meteorology class this evening. Lots of fun talking to the adults about the pros/cons of the business. Today definitely felt like the start of the "springtime" convective season. As I came out of the first school around 1pm, a very nice CB had developed over the middle of the area with a dark base and hail/big rain drops…big stuff for March 2nd in Portland. Just a sign of things to come in April and May, hopefully.
Of course we really just care about the cold upper-level troughs forecast to drop down over us (or just to the east) later Thursday-Friday and again on Sunday. There was a dramatic difference between the 12z ECMWF and 12z GFS. GFS was cold and showery with a good chance for snow to low elevations both periods. ECMWF pushed the trough much farther east with mild springlike weather. Drew and I (we collaborate on the forecast) went for a middle of the road approach. That leaves snowflakes out of the 7 Day forecast, but chilly weather from Thursday forward through early next week. The 00z GFS seems to have confirmed that now; a slight shift eastward with the Thursday trough and slightly warmer 850mb temps. I see it barely touches -7, about the time preciptation ends. So I'm glad we made that move. Sunday is still in play, but I wouldn't be surprised if/when the GFS backs off on cold air.
I could really use a nice big ridge with a few 70 degree days, but that's probably a bit much to ask in early March, especially in a La Nina year. One thing is still certain about the 7-10 day outlook; it's going to remain drier than average in this first half of March. A ridge well offshore with troughs dropping south along the coastline is not a very wet pattern…just some light rain at times…Mark Nelsen