Previsão do tempo, weather forecast: Frost, Record-Breaking Cold Temperatures, and Strange Weather Features

Cold air with snow and record-breaking cold temperatures moved in Saturday morning, with some odd weather features thrown in. And even an early snow record in Spokane.

Snow Spokane on Saturday,

Picture courtesy of u/VeeMeeVee

Temperatures this (Sunday) morning dropped to below freezing over both eastern Washington and much of the west--the first frost of the season for much of western Washington.

Take a look at this morning's minimum temperatures (see below, click on image to expand). Lots of below freezing temps in the west, but eastern WA really impresses, with cold valley sites getting into the single digits.

If you ever want to appreciate the cold-blocking capabilities of the Rocky Mountains, examine a broader plot of last night's lows (see below). Below-zero temperatures all over western Montana. The coldest air of the continental interior is blocked by the Rockies, and eastern Washington gets the warmed over cold leftovers. Western Washington, protected by the Cascades gets the tepid remains of eastern Washington's cold meal. A better stop this metaphor before it gets me into trouble.

Records-galore for cold and snow were broken during last 48h. For example:

Spokane had 7 inches of snow on the ground Saturday morning, the snowiest October day in their long 135 year historical record.
Spokane's maximum temperature of 31° F Saturday was the earliest subfreezing maximum temperature in the 135 year historical record.
-10 F at Cut Bank MT broke a daily record which had stood for 101 years.
-13 F at Puntzi Mtn Airfield in BC appears to be an October record low temperature:
A number of locations in the region tied or beat their daily record low temperatures for the date.

The visible satellite pictures had had a number of interesting features. The snow across eastern Washington is clearly evident (blue arrow) in the imagery today and you can also view the considerable snow over the north Cascades.

Stranger perhaps is the thin tendril of clouds that extended westward from the Olympic Peninsula coast on Saturday and then swung to the south and southeast offshore (see below). This feature resulted from the easterly offshore flow, with northeasterly and southeasterly air flows (blue arrows) converging offshore and producing upward motion and that interesting cloud line.

The National Snow Analysis shows a big increase during the last week (left image is today, right image on October 18th).

And we are way ahead of last year at the same time (see below)

If you want to see an image that is a bit deceptive but a lot of fun, below is the current percentage of normal snowpack from the US Snotel network: TWO THOUSAND PERCENT OF NORMAL over NE Washington and nearly 1000% of normal over the north Cascades. Values that might cause inveterate skiers to run for their equipment! But this early in the season, such percentages mean little, as do the crazy low values we observed in late spring.