Pacific Northwest Weather

[Guest]

And I wouldn't be the calling someone else a back tracker... you were the one that made the Sea Tac prediction and then when you were wrong you said, OH but its a hard place to predict, I got the general temperature range correct. Great... You sure didn't say it was hard to predict there when you were getting your predicted highs back in february right.

[Guest]

And about me being a little 1 or 2 degrees off on the weather yesturday supporting over 70* weather... It don't take much of Urban heating to top the temps out at 71 or 72 when a temperature reading in the forest just down the road can be 4 or 5 degrees lower... Take all the black top and housing and buildings out of bellevue and put down a layer of Cedars, they don't break 70... Sure i may be going out on a limb, but i learned from the best TT... sound familiar?

[andycottle]

Latest GFS this morning still showing showers for us on Sunday afternoon as a 1008MB low comes up from Southern Oregon. As the low makes it`s way toward us, it`ll bring mild temps and a very unstable air mass as 850MB winds are from the SW with temps around +9C. 500MB winds are in a SE direction for Sunday afternoon/evening. Also, lifted indices look to be about a -1 or -2 per ETA and AVN. Per MM5 model, CAPE values are in the 200 J/KG range. MOS for sunday is showing a high of 57....but with such strong SW flow, think temps will be much warmer and in the mid 60`s to near 70.

-- Andy

[snow_wizzard]

Finally! Some of my predicitons are coming to pass. I emphasized the low clouds for today and we sure have them. The NWS has also added thunderstorms to the weekend forecast now. The latest model runs are showing some really low lifted index values even tomorrow, so we may be in business!

[snow_wizzard]

Andy...By Sunday we are fairly showery and 850mb temps are at 3 or 4C. That should equal highs in the mid to upper 50s.

[TT-SEA]

Snow_Wizzard... what are you looking at????

The latest 18Z run of the NAM has very high 850mb temperatures all weekend and sunshine for most of Saturday and Sunday.

AND... southeast flow pulling up warm air from the Desert Southwest.

This could be a VERY warm weekend!!

Low clouds breaking up now and temperatures should climb nicely this afternoon. Even warmer tomorrow.

I think this warm spell is progressing VERY nicely!!

[TT-SEA]

We have to make a bet on the weather for Sunday!!

I see some sunshine... offshore flow... and 850mb temperatures near 15C!!!!!!

That could EASILY make my prediction of the last 10 days come true. There will be a few spots touching 80 degrees.

Mid 50's?????

You trust the GFS too much in this pattern.

[donsutherland1]

TT-SEA,

Specifically, since 1950 there have been 29 years where the block was sufficiently strong so as to bring the NAO to -1.500 or below during the April 20-May 5 period. If one goes by a -2.000 or below NAO, the sample falls to 18 seasons.

Finally, with the seasonal transition, it is not uncommon for some fairly "unusual-looking" patterns to occur in April-May, just as it is not unusual for hurricanes/tropical storms to take some pretty interesting tracks e.g., loops, etc., during October-November with the fall seasonal transition.

[snow_wizzard]

TT...I am looking at this.

http://itg1.meteor.wisc.edu/wxp_images/ ... 50_h84.gif

4C on Sunday. Not very warm!

How about this?

http://itg1.meteor.wisc.edu/wxp_images/ ... 0_h108.gif

2C on Monday! You are wrong. It will never get as warm as you are saying on those two days.

[R-Dub]

Reminded me of a Summer day today, low clouds in the morning that burned off around 10:00AM to full sun.
Now currently at 2:40PM its Sunny with a temp of 62 degrees.

This morning walking out to my car to go to work at 5:15AM the air just had that summer feel and smell to it, hard to explain, but its the first time this year that I have felt that. I think we may be running irrigation at the course real soon if this weather keeps up!

[snow_wizzard]

Even the ECMWF is showing 850mb temps of 5 for Sunday and Monday. The NAM is sometimes out to lunch on unusual patterns.

R-Dub...rain is coming this weekend.

At 2:30 we are sitting at 58 degrees. Nothing special!

[TT-SEA]

Here is Saturday afternoon...




Now... Sunday gets even warmer. But this website only goes out through 60 hours and I wanted to show you in full color unlike the NCEP website.

This is from the 12Z run of the NAM... the 18Z run is warmer.

[snow_wizzard]

I am betting that model is wrong. You don't know for sure it's right. It is the outlyer. I do not doubt that Saturday will be pretty warm. Sunday is another matter. The GFS shows that as a cool and wet day. The ecmwf is pretty cool too.

[TT-SEA]

When predicting rain with offshore flow... remember the GFS does not even know the Cascades exist!!

[AnthonyC]

A nice day...I was expecting better, but not bad for the end of April. Alot of morning clouds...they didn't burn off until 11:30am. And now alot of high clouds...currently 62F.

As for the rest of the forecast, I don't know who to believe. The GFS brings significant rainfall to the area this weekend...but it also has afternoon high temperatures in the 70s. I can't picture significant rainfall with temperatures that high...unless it came with thunderstorms.

At this point, it's anyone's guess.

Anthony

[TT-SEA]

O.K... this is going to be interesting.

The GFS and the NAM are farther apart with the DETAILS in the short-term than I have ever seen.

The funny thing is... they AGREE on the upper-level pattern.

I trust the NAM much more when it comes to the details. The GFS just fails miserably in complex situations because of our topography (which the model assumes is FLAT).

Now that being said... there will be some scattered showers and thunderstorms around. The MM5 shows that to be the case.

But it looks to be scattered and the temperatures stay warm. Maybe even humid!!

[TT-SEA]

We are at 65 degrees with sunshine after a low of 46 degrees.

Both of which are above normal.

[TT-SEA]

There will some scattered showers around Friday-Sunday.

But it will not amount to much and it will be warm. There is no cold air coming... particularly not with southeast wind flow at the upper levels.

[R-Dub]

Sounds like NWS is leaning towards the drier solution, hope they are right, would like a decent weekend for a change

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SEATTLE WA 330 PM PDT THU APR 21 2005

OVER THE LAST COUPLE OF DAYS THE GFS HAS BEEN INCONSISTENT AND LIKELY MUCH TOO STRONG IN HANDLING THE CANADIAN LOW...WHICH WILL AFFECT THE MODEL HANDLING OF FLOW AND QPF OVER WASHINGTON AS IT INTERACTS WITH THE LOW NEAR SW OREGON. THE MUCH WEAKER CANADIAN GEM SOLUTION LOOKS MUCH MORE REALISTIC. HAVE LEFT THE FORECAST UNCHANGED SINCE THERE WILL BE SOUTH FLOW AND A LIKELY UNSTABLE AIR MASS OVER THE AREA...POPS ARE ONLY IN THE CHANCE RANGE AND WITH THE MODEL INCONSISTENCY THERE WAS NO REAL BASIS TO FINE TUNE THE SHOWER COVERAGE. LIKEWISE THE CHANCE OF THUNDERSTORMS PROBABLY COVERS TOO MUCH OF WESTERN WASHINGTON...BUT THIS HAS BEEN LEFT ALONE AS WELL SINCE THE CHANCE OF THUNDER CAN`T BE ELIMINATED. SUNDAY UNCHANGED AS WELL. MON-THU...GFS INCONSISTENCY OVER THE WEEKEND...GENERAL OVERALL PATTERN AND WEAK FLOW OVER THE AREA ARGUE FOR MORE OF A CLIMO FORECAST FOR EARLY NEXT WEEK. WITH NO BASIS FOR TARGETING PRECIP ON ANY GIVEN DAY AND THE OVERALL PERIOD LOOKING MOSTLY DRY...HAVE DROPPED PRECIP FROM THE FORECAST. MAKES NO SENSE TO BUY INTO MODEL DETAILS THAT FAR OUT WHEN THE MODELS ARE INCONSISTENT. KAM &&

[snow_wizzard]

Well...It looks like a showdown TT! The GFS is acutally 1C colder and wetter for Sunday than the 12z. I wholeheartedly agree that the disagreement between the GFS and ETA is the worst I have ever seen. For the difference to become greater as the timeframe narrows is bizarre! The thing that you and some of our other friends on here are not taking into account is that the GFS is showing a cool southerly flow. Yes folks...under special circumstances cool air can come up from the south. If you look at just the 500mb map you would certainly think Sunday will warm. But the 850mb map (at least with the GFS) is quite cool for Sunday. If we indeed have 850mb temps of 3 or 4C and heavy showers on Sunday, it could be a cool day! I think we have both committed ourselves and may the best man win!

I am also quite excited about the NAO going negative, like Don has been talking about. If you look at the years that had strongly negative NAO in April, you will find that many of them are years that I like! It also adds support to two of the analog years I have come up with (all of my other years, except 1993, are before the NAO records begin). As for 1993, the NAO was not negative in April, but it was in May. By the way, if you look at the Palmer temperature records for the winter 1993 - 94 it was pretty darn cold overall. The same is true for Clearbrook (very near Sumas). It seems that the cold air stalled just to the north and east of Seattle that winter. Any little change in details could have delivered the goods. What I am saying is I would rather have a year like that as an analog than 1986, for example. That was one of many winters we've had that didn't have a chance!