Pacific Northwest Weather

[snow_wizzard]

The weekly average temperature in Covington this week was 38.9 degrees. A rather cold spring, I would think!

That is too cold to support plant growth...sorry guys.

[R-Dub]

We have some crunchy frozen grass up here this morning, have a feeling the roads will be the same from the over night rain, and now close to freezing.........Well off to work.

2/13/05 LK Goodwin WA
6:16:11 AM CURRENT
Cloudy
Temperature (ºF) 33.8
Humidity (%) 100.0
Wind (mph) SW 3.7
Daily Rain (") 0.02
Pressure ("Hg) 29.98
Dew Point: 33.8 ºF

[TT-SEA]

Help me guys. Please.

Show me where there is cold air is forecasted to be on the same side of the continent as Seattle on the ECMWF maps. This model has been by FAR the best model this winter. You need to address what the ECMWF shows because if you do not have support here for an arctic blast... it will not happen!! Show me where the cold air is.

This is Tuesday afternoon...



And Thursday afternoon...




And finally next Saturday...




Where???

[vbhoutex]

TT, I don't want to be thorn, especially since you probably know as much or more about forecasting than I do. But I beleive back in this thread somewhere it was stated that you need to be looking at surface obs too, especially when dealing with your area. I understand what you are saying looking at the 850mb temps, but if it is a shallow air mass then they may be a little misleading. Granted, what I have been reading and seeing puts the main blast of Arctic air well to your East, but is there a chance that some of it could "sneak" in from the NE. Again, I am not at all versed how different the weather is in your area when it comes to how the air moves. Here in TX it is very straightforward how it all works at this time of year as far as where it all comes from. Just my 0.02 worth.

[andycottle]

Good morning all. Viewing this morning 06 and 12z GFS....15th through about the 17th still remaining mostly sunny, dry and somewhat cool. Saturday may also end up being dry and partly cloudy, though 'might' see a stray sprinkle late Saturday afternoon into evening hours. Looks like the main rain maker doesn`t come in around till 18z Sunday. So in the shorter term and after this bout with showers, we can look foward to some sunny days ahead, with the exception of maybe a little morning fog here and there. -- Andy

[TT-SEA]

Yes... outflow can make a difference. Particularly at night... with clear skies which it looks like we will have.

But this scenario is totaly wrong for an arctic outbreak or lowland snow. Sure it can get cool at night with good outflow... but the sun is pretty strong now and that means we can get up to 50+ degrees even after a frosty morning. That means spring even if the average temperature is 40 degrees.

My idea of winter cold is highs in the 30's and lows in the teens and 20's... then we get some moisture and we have a lowland snow event. Its too late in the season for outflow under mild 850mb temps and sunshine to make for winter cold.

[R-Dub]

Had a layer of hail/ice on the greens at work, still there in a few areas. Thanks to the good old convergance zone early this morning.
Our low was 31 degrees

2/13/05 LK Goodwin WA
9:41:39 AM CURRENT
Partly Cloudy
Temperature (ºF) 36.0
Humidity (%) 99.1
Wind (mph) S 0.0
Daily Rain (") 0.24
Pressure ("Hg) 30.12
Dew Point: 35.8 ºF

[R-Dub]

Sounds like much uncertaintly in the extended, a little change in the pattern could mean big differences in the weather.....................

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SEATTLE WA 909 AM PST SUN FEB 13 2005

.DISCUSSION...TWO SHORT WAVE UPPER TROUGHS TO OUR NORTHWEST WILL ENHANCE SHOWERS OVER THE AREA OVER THE NEXT 24 HOURS OR SO. THE FIRST IS ABOUT 100 NM OFFSHORE EARLY THIS MORNING AS SEEN ON SATELLITE IMAGERY AND HAS A BATCH OF COLD AIR ALOFT...PRODUCING OPEN CELL SHOWERS WITH TOPS NEAR 20000 FEET AND CLOUD TOP TEMPS AT OR BELOW -40C. 500 MB TEMPERATURES IN THIS AREA OF INSTABILITY COULD BE INFERRED AT -35C...CLOSE TO NAM 12KM MODEL PREDICTION FOR KSEA THIS AFTERNOON. EXPECT THE CONVERGENCE ZONE AND SHOWER ACTIVITY TO ENHANCE AS THIS FEATURE PASSES THIS AFTERNOON AND CAPES REACH 250-500 J/KG WITH CONVECTIVE TEMPERATURES IN THE MID 40S. COULD SEE A CLAP OF THUNDER IN THE CONVERGENCE ZONE. THE NEXT WEAKER SHORT WAVE TROUGH IS NW OF THE CHARLOTTES AND APPEARS TO BE TIMED TO COME THROUGH THE AREA AFTER MIDNIGHT TONIGHT. THIS WILL KEEP SOME SHOWERS ESPECIALLY IN THE CASCADES AND CONVERGENCE ZONE GOING THROUGH MON MORNING. IN THIS MIXED AIR MASS WITH ONSHORE FLOW AND 850 MB TEMPERATURES NEAR -6C WILL SEE SNOW LEVELS BETWEEN 1000 AND 1500 FEET FOR THE MOST PART. GRAUPEL...SMALL HAIL...OR WET SNOW MAY OCCASIONALLY MIX IN AT THE SURFACE IN HEAVIER SHOWERS. SNOWFALL ACCUMULATIONS IN THE CASCADES SHOULD STAY BELOW ADVISORY CRITERIA UNLESS THE AXIS OF THE CONVERGENCE ZONE STAYS FOCUSES ON ONE OF THE PASSES FOR A LONG TIME...NOT EXPECTED AT THIS POINT. A REX BLOCK CENTERED BETWEEN 130W-135W DEVELOPS LATER MON AND CONTINUES THROUGH POSSIBLY NEXT WEEK. THROUGH THE EARLY PART OF THE PERIOD TUE-THU OFFSHORE FLOW AND DRY BUT COOL WEATHER IS EXPECTED. LARGE DIURNAL TEMPERATURE RANGES ARE EXPECTED WITH SUFFICIENT OFFSHORE FLOW AND A DRY ENOUGH AIR MASS TO INHIBIT FOG FORMATION. OVER NORTH AMERICA THE MODELS APPEAR TO BE PERFORMING WELL. UNFORTUNATELY NW WA WILL BE IN THE MOST DIFFICULT AREA WHERE NORTHERN STREAM ENERGY DROPPING S ON THE EAST SIDE OF THE BLOCK AND SRN STREAM ENERGY ROTATING AROUND THE UPPER LOW OFF NRN CA MEET. SMALL DEVIATIONS IN THE EVOLUTION OF THE REX BLOCK WILL HAVE LARGE FORECAST IMPLICATIONS OVER WA AND THE MODELS ARE SHOWING RATHER LARGE CONTINUITY AND CONSISTENCY PROBLEMS IN THIS AREA. IN ADDITION...THE 00Z GFS IS AN OUTLIER AS COMPARED TO OTHER ENSEMBLE MEMBERS IN SHOWING RATHER DEEP TROUGHING ALONG THE WESTERN US LATER THIS WEEKEND AS A RESULT OF A DEEPENING AND DIGGING NRN STREAM SYSTEM. MOST ENSEMBLE MEMBERS AS WELL AS THE CANADIAN MODEL GUIDANCE IS MUCH WEAKER WITH THE NRN STREAM SYSTEM AND KEEPS US IN NO MANS LAND BETWEEN SYSTEMS. THE ECMWF SEEMS TO SHOW MORE MID/HI LVL MOISTURE ASSOCIATED WITH DEBRIS FROM THE SRN STREAM SYSTEM. CONFIDENCE BEYOND THU IS VERY LOW. FORECAST CHANGES...WILL UPDATE THE SEATTLE...FOOTHILLS...AND CASCADES ZONES THIS MORNING TO INCLUDE A CHANCE OF A THUNDERSTORM AND TO INCLUDE POSSIBLE SMALL HAIL OR WET SNOW IN HEAVIER SHOWERS. OTHER THAN THAT THE SHORT TERM LOOKS GOOD.

IN THE EXTENDED WILL MAKE NO CHANGES AT THIS TIME...BUT WILL PROBABLY WANT TO CONTINUE THE BROAD BRUSH FORECAST FOR THE EXTENDED PERIOD FROM FRI THROUGH SUN GIVEN UNCERTAINTY IN THE DETAILS OF THE EVOLUTION OF THE REX BLOCK. ALBRECHT

[snow_wizzard]

It certainly looks like the pattern that has dominated so much of this winter may be about to collapse. The last two GFS runs indicate a possible cool and moist westerly flow by the end of the week. This could spell significant snowfall in the mountains! At this point that would be as satisfying to me as an Arctic outbreak. I would certainly like to see the 0z be right, but either solutions is OK by me. The ECMWF also shows a much less blocked pattern with decently low heights by days 7. It would appear that the collapse of El Nino may pay off very soon. One also has to wonder how much longer the weather will take to really react to the negative running PNA average. The running average went negative a few years ago, and we still have yet to really get anything out of it. Past history is clear that a negative running PNA average spells lots of cold weather. There is a decent chance this late winter and spring will be of the cold and nasty variety...time will tell.

As for the next couple of days. Prepare for a very nice winter chill. 850mb temps of -7 to -8 tomorrow in combination with brisk north winds will spell a delicously crisp day! Tomoorw night will be cold in all areas with clear skies, a cold airmass, and light winds. Tuesday night will have lows in the low 20s in the wind sheltered areas, and 30s in the breezy areas. A much colder east wind than last week! I still think some areas will have snow tonight. We shall see.

[R-Dub]

Here is the latest PNA forecast..................

http://www.cpc.ncep.noaa.gov/products/p ... _ensm.html

[R-Dub]

Just looked at the state cams, and it looks like Heckelsville shed (just west of PT Angeles, and around 500FT I think) got a dusting of snow, and the skykomish airport(1,000FT I think) got a couple of inches.

Mostly Cloudy here at the moment, with the temp of 37.6 degrees. Pleasant, but cool here.

[snow_wizzard]

This is the 850mb temp map for tomorrow night. I would not call this warm...this is as cold as it's been all winter.

http://itg1.meteor.wisc.edu/wxp_images/ ... 50_h48.gif

[W13]

I'm back from my trip south to Oregon, and I was surprised that there was no snow at my cabin at nearly 2500 Feet as of yesterday afternoon. It did get some snow last night, though (apparently down to 1500 feet had measurable snow this morning).

On our drive back up to Kent this morning, we had about a 50 miles tretch that was at or below 28 F (about from Exit 71 Onalaska/Napavine, to just south of Olympia). Was nice to see frost in the fields.

For tonight, I expect that at least some areas will see some snow. I think the PSCZ may be strong enough when it fires up tonight to drift more towards the Pierce County/King County line. This would be a great scenario for me and snow_wizzard tonight.

[R-Dub]

Here is what WXRISK is saying..........

http://www.wxrisk.com/wxalert.html#A

[R-Dub]

Currently snowing again at Heckelsville shed..................

http://wsdot.wa.gov/traffic/default.aspx?cam=1143

[R-Dub]

2/13/05 LK Goodwin WA
12:21:45 AM CURRENT
Mostly Cloudy
Temperature (ºF) 40.4
Humidity (%) 86.8
Wind (mph) SSW 1.3
Daily Rain (") 0.24
Pressure ("Hg) 30.13
Dew Point: 37.8 ºF

[W13]

Currently 41 F, with a Dew Point of 32 F as of 1:43 PM.

[W13]

Currently 42 F, with a Dew Point of 32 F as of 1:54 PM.

[R-Dub]

In the last 10 minutes it has gotten very dark here! Almost black looking clouds just to my north and west. Has that erie quiet sound outside, I think we are about to get dumped on here in my area!!

Current temp 40.9 degrees

[AnthonyC]

Ahhhh, good to be back in Seattle. Just as I left, another partly sunny afternoon but cool temperatures for the middle of February. If a PSCZ develops tonight, things could get very interesting for my area...850 mb heights drop to -9C tonight.

As for the extended, models continue to diverge showing broad, weather possibilities. Almost all models develop a REX block beginning Monday afternoon, but there's still uncertainty on the strength and position of the block. As of now, 135W looks like the best place and it looks like a moderate-strength block. With this scenario, expect mostly sunny skies with seasonal temperatures...though Monday and Tuesday look chilly.

I won't even touch next weekend because not one model is in good agreement. The GFS wants to bring down the northern branch and develop a significant trough over the PNW, the Canadian model brings the northern branch down but to a lesser extent than the GFS. The European model continues the REX block but eventually hooks up with the southern branch to bring some moisture...but warm temperatures. In any event, it's still too early.

Anthony

Currently 43F with mostly cloudy skies.