Wind, Rain, and Snow

March 19, 2013

11pm Tuesday…

A bit late posting tonight, but everything is progressing pretty much like expected. East wind has been gusty in the Gorge, peak gusts 50-60 mph earlier. South wind just now starting to appear at the Coast and it’ll ramp up quickly the next few hours. South wind arrives in the Valley by daybreak too.

Nice and wet out there and mostly steady rain should continue until daybreak. Then it’s on to the shower/sunbreak/hail spring routine.

I’ve been analyzing all the maps/models with regard to low snow levels…I’ve got a few thoughts:

All models are very chilly Thursday morning through Saturday with snow levels (especially overnight hours) regularly down to 1,500′ or lower. Each afternoon it’ll be up around 2,000′ or even a little higher…it’s Spring and sunbreaks do wonders. But for several reasons I don’t think we’ll get snow much lower than 1,000-1,500.

1. NW Oregon is really on the southern edge of significant moisture during this period, for example it’s mainly dry from Florence over to Eugene. Not totally dry, but the deeper moisture is farther north closer to the upper-level disturbances passing by.

2. Without the good moisture, I don’t expect real heavy showers to drag the snow level down much below 1,000′. Our RPM has NO precipitation over Portland from Thursday evening through Friday evening. The 4km WRF-GFS is similar.

3. There may be sticking snow lower than 1,000′ in the Coast Range and maybe some spots on the west slopes of the Cascades.

Any of us could see snow mixed in with the showers Thursday and Friday…it’s going to be a chilly couple of days!

For skiers, as I mentioned not a ton of moisture, so a nice snowstorm, but not a huge one. Maybe 12-18″ the next 3 days up there: Here’s our evening RPM model snow forecast:

RPM_72_SNOW_00z

Keep in mind the forecast snow for Hood River and The Dalles is just due to contouring issues on the map…it won’t snow in those locations.

Milder, and drier weather returns next week for Oregon’s Spring Break. Definitely not DRY, but DRIER.   Here is the 00z GFS ensemble chart showing upper-level temperatures returning to average next week:

tseries_850t_000-384_Portland

Chief Meteorologist Mark Nelsen