Wednesday, December 29, 2010

Convergence Zone Snow


As shown below, the convergence zone snow is continuing and strengthening in southern Snohomish County....some of the roads have gotten problematic.


You can watch this event unfold (and know what is going to happen to you during the next hour) by viewing the radar animation:

http://radar.weather.gov/radar.php?rid=ATX

http://www.atmos.washington.edu/weather/radar.shtml

Latest NWS Spotter Reports"

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
747 AM PST WED DEC 29 2010

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..

0600 AM SNOW 3 NE MILL CREEK 47.89N 122.16W
12/29/2010 M1.0 INCH SNOHOMISH WA NWS EMPLOYEE

SNOWING. VISIBILITY BETWEEN A HALF AND THREE-QUARTERS OF
A MILE. SNOW ACCUMULATING ON THE ROADS. ELEVATION ABOUT
500 FEET.

0700 AM SNOW 5 NNW EATONVILLE 46.94N 122.31W
12/29/2010 M2.5 INCH PIERCE WA TRAINED SPOTTER

SNOW HAD STOPPED. ELEVATION 740 FEET.

0729 AM SNOW EVERETT 47.96N 122.20W
12/29/2010 E2.5 INCH SNOHOMISH WA PUBLIC

SILVER LAKE AREA

0730 AM HEAVY SNOW NW DUVALL 47.73N 121.97W
12/29/2010 M2.0 INCH KING WA TRAINED SPOTTER

TWO INCHES IN 30 MINUTES. STILL SNOWING HEAVILY.


WSDOT is on top of this--here are some of their latest reports:

7:43 a.m., Wednesday, Dec. 29

Good morning,

Driver alerts:

  • I-5 at 164th Street SW: Several disabled vehicles are blocking the northbound I-5 exit to 164th Street.
  • I-405 near Alderwood: Multiple spinouts are blocking the two right lanes of southbound I-405.
  • I-405 near Canyon Park: A disabled vehicle is blocking the northbound carpool lane just north of the interchange with SR 527.
Seattle is pretty much untouched by this at this point....

15 comments:

Upupaepops said...

I see Sound Transit did not pull articulateds.

I work in Canyon Park so I guess I will go in this afternoon instead of this morning , as planned.

Todays convergence zone doppler looks exactly like the previos days forcast map. Excellent work!

I am learning so much here.

snapdragon said...

It just finished snowing in Hazel Dell (SW WA). Very wet, barely sticking. Pavement is wet- not white.

Indy Falconheads said...

Just started snowing in Shoreline. Big wet flakes too!

Ferdi said...

Heavy graupel showers this morning, 8:45 AM, over Sinclair Island with brisk north winds. Temp. 34 degrees. From observations I've concluded that in a northwesterly flow the San Juan Islands experience a convergence zone created by Vancouver Island. Often in summer the wind will be northwest on Sinclair Island and southwest on Guemes Island a few miles to the south. Orcas Island seems caught in the middle.

Patrick said...

Snow has been falling in Wedgwood, 45th Ave. NE & NE 75th St. No accumulation yet, but it is starting to stick to plants.

Christopher said...

Started snowing at sea level in the San Juans at about 10:00. Still going strong at 10:20. Sticking to grass and porch decks (can't see road from where I am but is sticking to driveway.) Not much accumulation yet, maybe 1/4", but the grandkids (3 y.o.) are hoping to get a chance to use their new sliders they got for Christmas.

Alex said...

Novelty Hill Road is closed from Avondale to 243rd.

Fildrigar said...

No snow sticking at sea level in downtown Edmonds. The wind, however, is SCREAMING in, pounding the waves up over the seawall.

kosmo said...

Wednesday, 7:30pm: Thundersnow and hail going on now in Federal Way. Lightning and thunder for the last 30 mins. Roads covered quickly. Did not hear thundersnow and lightning forecast. Models?

Bill Clugston said...

About 7:45 PM in Auburn and we had thunder and lightening along with snow pellets. Cliff, what causes the snow pellets? They never seem to last very long.

Christopher said...

Will somebody please figure out how to get Mother Nature to listen to and obey the forecasts?

Western Washington Zone Forecast for our area says "light wind" tonight.

GFS Initialized Pacific Northwest WRF Weather Forecasts from the US atmos site, 12 km surface (10m) wind speed loop shows 10 mph here except for one frame where we are on the edge of 15 mph.

NWS Point Forecast for our exact location, Tabular Forecast, shows wind 14 mph at 9:00 diminishing to 9 mph after midnight.

And NOAA Graphical Forecasts for Seattle, Wa wind loop shows nothing over 15 mph all night.

But Mother Nature is throwing us steady wind in the mid to high 20s with a 30 here and there, and with gusts in the thirties and an occasional 40.

Somebody please tell Mother Nature that this is NOT supposed be happening, and get her back on the same page as the forecasts.

Steven said...

This evening between 6 and 9 pm sometime we received some precipitation in Parkland (south of Tacoma) I'd never seen before. It looked like styrofoam beads -- much fluffier and lighter than normal hail, but much larger, spherical and heavier than any snow I've seen. Is there a name for this type of stuff?

Teri, Nancy & Sue said...

Driving north on I-5 from Tacoma and past Federal Way at about 7:30 this evening, very unusual lightning and extremely fast dump of something between snow pellets and hail. Covered the road surface within minutes! I thought lightning and thunder were usually associated with warm weather??

Targhee said...

Not to be picky, but as an engineer and scientist, terms matter. The "thundersnow and hail" we had in Tacoma from 744-747 pm Wednesday is called graupel. Hail hurts (I used to live in DC, and have been in Denver during hailstorms). Graupel is like styrofoam beads falling from the sky.

windlover said...

Here's a great article by Scott Sisteks blog from Komo explaining what the "strange hail" is....



http://www.komonews.com/weather/blogs