Thursday, January 21, 2016

Atmospheric River Update

It has been very wet over the region during the past day.   Here is the 24 hr precipitation ending at 10 AM.  The southern side of the Olympics  and the coastal mountiains have gotten 3-4 inches, with1.5-2 inches over portions of the north Cascades.   And what a rainshadow!  Only .04 inches over northern Whidbey Island.  Puget Sound country has been drenched by 1-2 inches.


The aircraft soundings over Sea Tac Airport shows that profound warming and strong southerly/southwesterly winds moving in aloft (time increases to the left, height is in pressure, 850 is about 5000 ft)

Right now strong easterly flow is maintaining cool air in the passes, where it is still snowing (hard).   This is wet dense snow.  The latest model runs suggest that the warm air air wins out and the precipitation will turn to rain in the passes during the afternoon.  With heavy snow on the mountains, with a good chance of rain on top of it, the avalanche threat is serious.  The passes are  now closed and the NW Avalanche Center is showing high avalanche danger in the mountains.


6 comments:

Mark said...

24-hour rain at my house on south Vashon is 1.28 inches. 31.04 inches since October 1, 2015. 4.40 inches so far in January. For now, the AR has lifted a little northwest of my house.

A quick review of the 1997/98 super El Nino shows northern California receiving persistent heavy rain. Tornados across Florida, record rains in the southeast and a severe ice storm in the northeast. Southern California was doubting El Nino would deliver the promised rain. Rains did come to S. Cal in Feb and March. In the PNW, Precip was a little below normal and temps a little above normal. Temps were much above normal across the northern plains.

This El Nino is similar but with twists bringing more rain to the PNW. Again, lots of rain in northern Cal but not as extreme as 97/98. Tornados and flooding from Texas to Illinois and a forecast blizzard in the Washington D.C area. My home stomping fields in Minnesota enjoyed a record warm December. The snow cover didn't stick until about Christmas. But Arctic air came in January with consecutive sub-zero days, lows around -18F and wind chills down to -40F. Good for ice skating and fishing. It has been cold in Minnesota but 10 to 15 degrees F above record low levels.

I looked at past snowfall/depth at Donner Summit, central Sierras. I was a little surprised to see that the snow depth during the 97/98 El Nino year was about average. The winter of 2011 brought near record snow depth to the central Sierra mountains followed by the record drought. The super El Nino of 1983 did bring much above normal mountain snows to central California but not a record amount.
http://www.thestormking.com/Weather/Sierra_Snowfall/sierra_snowfall.html

According to NOAA, the global temperature anomaly for December 2015 was a record +1.11C (2.0F). Still within the safe zone of < 1.5C. This compares to the December 1997 global temp anomaly of 0.62C. Our planet (for December) has warmed about 0.5C in 18 years. If the trend continues then around 2023 (next super El Nino) a monthly global temp anomaly will exceed the 1.5C Safe Zone. Interesting times ahead.

I'm still bucking up downed trees from the wind/rain storms of last Nov. and Dec.



Flying Bear said...

Amazing differences between South Whidbey and North Whidbey Island. Here in Langley, WA our weather station has reported 1.5 inches today.

David B. said...

As of 10:30 pm tonight, I've had 2.61" in the past 24 hours here on Bainbridge Island (Winslow area). Looks like the storm total will exceed 3" here.

Mia Vermillion said...

I'm in Skyline neighborhood on Fidalgo island. My experience had been Cliff's rainshadow. I was walking my dogs to dry skies yesterday and experienced a tinsy bit of rain yesterday.

Travis said...

1.97" here in Bothell.

John Marshall said...

Here on Bell Hill in Sequim we've only had 0.52 inches in the last three days. It was actually sunny for quite a while this morning. Felt nice to bask in the sun while walking the dogs, watching distant rainbows to the west. This has been a truly excellent January so far, at least here.

These storms moving SW to NE are usually heavily shadowed, resulting in sprinkles for most part.

But at least the surface soil is moist again, and the Dungeness River and the area's irrigation ditches are very full. The river being this wide is helping recharge the near-surface aquifer, thanks to the far heavier rain up in the Olympics.