Sun Dogs and Cold Temps

January 21, 2009

IMG_3612  A nice picture of a sun dog from Tim in Cedar Mill today.  I have a link on my weather page to the Atmospheric Optics page.  Or you can just click on that link to find our FAR more than you want to know about different visual phenomena in the atmosphere.

Okay, moving on to the weather…east wind TRYING to die down again this evening.  We've gone all the way down to a 6.5 mb. PDX-DLS gradient…I see TTD has only gusted to 33 mph the last 6 hours, and Corbett has stayed below 60 degrees.  The process continues tomorrow, so gusts should be below 40 mph even in the Gorge.

There are some echoes showing up on radar offshore this evening as a dying system moves onshore.  A sprinkle wouldn't surprise me, but we have a very dry airmass down at the surface, so freezing rain seems unlikely.  There's no chance for snow with temps in the 30s and 40s up at 4-6,000'!

For those of you out on the eastside wanting to get rid of the wind completely?  Hmmm, that's a problem.  Cooler air starts pouring back into Eastern Washington Friday, allowing the surface high east of the Cascades to "reload", which means easterly flow through the Gorge strengthens again.  That will be with us then through the middle of next week…sorry folks, no big warmup is coming for the frozen Gorge (or nearly frozen).

Some changes in our forecast this evening.  Those of you who watch the maps closely probably know what I mean.  18z and 00z GFS and now the 00z NAM have some moisture over us Sunday.  It is "spun up" by an upper level trough passing overhead at the same time a modified arctic front passes south at the surface.  Precipitation Sunday morning is accompanied by increasing easterly flow (30kts at 2,000'!) bringing in dry and cold air from the east.  Seems a bit like December 14th, when we had little or no snow in spots, but more in others.  One thing that is different is the airmass is not nearly as cold.  We are saying temps stay in the mid-upper 30s Sunday and Monday.  If current trends continue, those still need to come down by about 5 degrees for Sunday and Monday.  But that's still 3-4 days away…plenty of time to "fine-tune" the forecast.

This appears to be a one-shot deal for cold air…it's back to some sort of mild westerly flow or ridgy conditions Tuesday and beyond…Mark Nelsen