Saturday, February 25, 2023

anything is possible..

but weather models can crank out some curious results at times.

We're on the cusp of another 3" snowfall beginning in six hours.. and again the NWS is shading things toward the warmer, less-drastic end of things. Last week when the forecast expected 1-2" NE Portland got over ten inches - that's not in the cards overnight (don't ask about Sunday night!), but odd things are happening. The Winter Storm watch has been dropped here, now maybe 1-2 inches will land at 750 feet. But how's that done?

According to the output at left, for 4-6 hours just after midnight (with temps 31° and dewpoint around 30°) the snow turns to .36" of rain. Not sleet or fz-rain, just rain. That 0.36" would be about three inches of snow if it magically remained frozen - like it shows at 11PM and 6AM. Curious, captain.

If this isn't breaking a law of thermodynamics, it's at least bent or twisted a bit.

Then comes Sunday night, where a low center could stay due west or make land further south. Last week it stalled completely just south of Astoria and spun up moisture that pounded Portland/Vancouver while leaving us the 3" that remains today. While speaking in ominous tones the model output is 1½". 

And the next few days we're in and out of the snow zone, with white mornings and damp sunsets. That'll teach people not to live in our elevation band - though I've never seen a forecast look like that for multiple days around here.

Time will definitely tell.. whatever the models say.

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