Pacific Northwest Weather

[TT-SEA]

Overall... a BEAUTIFUL day out there. Sunny with excellent visibility and pleasant temperatures despite being cooler than normal.

Had to drive over the I-90 bridge on Lake Washington... awesome views of all the mountain ranges and the lake glistening in the sun. Seattle is shining today!!

You guys should read the thread titled "January 16 - January 31, 2005 Pattern Discussion" just posted. Very interesting. That guy knows his stuff.

[TT-SEA]

From the expert on global patterns (donsutherland1)... a shift to a stongly negative PNA is unlikely.

Given the fact that the PNA was extremely negative (off the charts) last week and we got basically nothing... I am not hopeful for a return to winter.

My educated guess (also given a weak El Nino) is that the rest of the winter will be relatively mild and wet. Hopefully this translates into lots of mountain snow though!!

[TT-SEA]

A great discussion this afternoon out of Spokane (it has no bearing on what happens in Seattle... but still interesting).

Did you know that with an arctic air dome over a region... the mountains are "masked" and there is NO difference between the valley floor and the top of the mountains in terms of snowfall received?? Fascinating.

Here is an excerpt from their discussion...

THIS NEGATIVELY TILTED PIECE OF ENERGY IS EXPECTED TO
PUSH A SIGNIFICANT WARM FRONT NORTHWARD THROUGH THE INLAND NW
BEGINNING SATURDAY EVENING OVER THE SOUTHERN ZONES AND SPREADING
NORTHWARD OVERNIGHT. PRECIPITABLE WATER PROGS ARE QUITE IMPRESSIVE
AND GENERALLY MATCH WELL TO THE CURRENT AMSU VALUES. THIS IMPLIES
THAT THE VALUES WILL REACH OR EXCEED .50 INCHES OVER THE INLAND NW
BY 12Z SATURDAY. THIS BY ITSELF IS NOT TERRIBLY IMPRESSIVE...BUT
WHAT IS IMPRESSIVE IS THE MODELS KEEP THE ATMOSPHERE BELOW 850 MBS
WELL ENTRENCHED IN THE ARCTIC CHILL. THIS OBVIOUSLY EQUATES TO
WONDERFUL ISENTROPIC ASCENT AS ANY BIT OF OVERRUNNING AND MOISTURE
ADVECTION WILL RIDE RIGHT OVER THE TOP OF THE ARCTIC DOME. IN THESE
SITUATIONS...IT IS NOT UNCOMMON TO RECEIVE JUST AS MUCH SNOW OVER
THE VALLEYS AS THAT WHICH FALLS OVER THE MOUNTAINS...SINCE THE COLD
AIR DOME ESSENTIALLY MASKS THE MOUNTAINS IF DEEP ENOUGH. THIS WILL
LIKELY BE ONE OF THOSE SITUATIONS. WITH THE FRONT WEAKENING AS IT
MOVES NORTHWARD...WE EXPECT IT TO LOSE SOME OF ITS NORTHWARD
MOMENTUM AND CONSEQUENTLY...IT MAY END UP SITTING OVER SOME PORTION
OF THE CWA FOR A PROLONGED PERIOD. SO WHILE QPF VALUES WILL NOT BE
TERRIBLY HIGH OVER ANY GIVEN AREA...THE CHANCE OF A STALLED FRONT
COULD RAISE THEM SIGNIFICANTLY OVER ANY GIVEN AREA. NONETHELESS...
EVEN THE QUARTER INCH QPFS WE EXPECT OVER MOST OF THE CWA THROUGH
THIS PERIOD WILL EQUATE TO AT LEAST 20 TO 1 SNOW RATIOS...WHICH
SUPPORT HEAVY SNOW WARNING CRITERIA FOR THE VALLEYS.

[W13]

35 F with a Dew Point of 15 F, as of 3:23 PM

[W13]

If we get below about 20 F tonight, which I think we will at least in my area, then if clouds start rolling in fairly early tommorow we are in pretty good shape for most of Saturday Night, possibly even into the early morning hours of Sunday.

It will be interesting if NWS decides to issue either a Winter Storm Watch, or just a Winter Weather Advisory.

[R-Dub]

That is very interesting TT! I didn't know that.

I know this situation is different in many ways, but I remember the Dec 96 storm, that saturday in the afternoon before the warm overrunning storm moved in, it had warmed up to about 35 or 36 degrees, things started to drip and turn a little slushy. Then about 3 in the afternoon the NE wind picked up in advance of the storm (tracking very similar to the one coming for the weekend) and the temp went down to 23 degrees in 1hr. by that evening we were down to 17 degrees with the blizzard conditions. If I remember right the temps were very similar to what they are now in E washington. Would it be possible for the same thing to happen? I remember the turn over to rain was about 9 AM, after we had 2 feet of snow on the ground. I know we will get no where near that, but couldn't a similar situation happen where we could at least get 4-6" before the turn over?

[TT-SEA]

Does anyone have a surface map of the December 26, 1996 storm?

[R-Dub]

It would auctually be the 28-29th if I remember right. The 26th was the start of the snow, then 3 days later was the overrunning event.

[TT-SEA]

Actually... what was the date of the big storm in 1996?? I think it might have been 12/27.

[R-Dub]

I was just looking at the news coverage of that event, and the Sat picture showed a similar track, the difference is that one in 96 looked stronger. Maybe with it being that strong, it was able to really pull the cold air from E washington and north in advance of it. I would be nice to see a map of it though.

[TT-SEA]

Yeah... the historical data shows record snowfall amounts at sites around Puget Sound on 12/28/96.

[R-Dub]

The first system came through on the 26th, then we had convergance zones, and heavy showers on the 27th, then the 28th it was partly cloudy, but that night of the 28th is when the big overriding event happened. I am pretty sure anyway.

[R-Dub]

We had a lot of snow up north on the 26th I think around 13" places seattle south kept going between snow and freezing rain that day, so they had less with the first storm. Then it was all snow for everyone after that. I ended up with 26" at my house.

[Brian_from_bellingham]

That storm in late 1996 was a pineapple express kind of storm, but it started as snow because of the cold air in place. Though we may get a pineapple express next week, this storm is not quite that juicy, at least from what I have read. Still, places in Eastern Washington may get slammed. Lucky them. It is also interesting that in Whatcom County that December snow for us started on Dec. 21st up here.

[R-Dub]

Yeah I remember you guys up there being socked in long before we were. We would get an inch or two then melt, then another inch. We flirted with it for a good week or two.

I know we had the cold air in place, but like I said, we warmed to 36 degrees that afternoon, then in 1hr we had dropped to the low 20's. Something really drew the cold air back over a few hrs before that system came in.

[R-Dub]

Think I'll pull out my archives of that storm, I wrote down conditions at my house for that storm, now I just need to figure out where it is Would be interesting to see just how cold we got during those days in 1996.

[W13]

NWS still hasn't updated their Forecast Discussion ...


Current temp is down to 34 F with a Dew Point of 15 F, as of 3:51 PM

[Brian_from_bellingham]

On that morning on the 28th or 29th, we had 3 feet in the city of Bellingham, more then that elsewhere. I remember the snow being up to my waist. I know the snow drifts up north were tremendous, people had to abandon their cars and be rescued by the Search and Rescue team. The Weather Channel did a story about that in Storm Stories, but they focused on what happened north of the border in Canada, but it was the same thing up there. That was a classic case of the tug of war between cold air just to the north and warm moist air, and subtle differences in location made all the difference between rain and snow. We were not that far away from having it just be rain. In fact, just after the snow on the 21st, the original forecast called for a warmup before Christmas, but that turned out to be wrong, fortunately.

[W13]

The Zone Forecast has been updated, still no discussion out yet, though.

[AnthonyC]

The December 26-30, 1996 storm was amazing. I wish I knew the exact setup for that event. I know there was arctic air bottled up in British Columbia and a powerful surface low formed off the south Washington coast and then tracked inland over Portland. We probably received 10-14 inches on December 26. I also remember it wasn't brutally cold with that event...very marginal, maybe 29-33 F. The night of the 29th was amazing...it started snowing around midnight and continued until 6-7am, beforing switching to freezing rain and then rain. By the morning of the 30th...WHICH WAS MY B-DAY!!!...we had between 20-26 inches of snow on the ground...AND THEN CAME THE AWFUL FLOODING...

Anthony

Currently 29 F, dewpoint 19 F.