There have been a few people asking if I am nervous for the ceremony. I'm not really nervous (at least not yet) for the vows. Rather, I am more nervous about the weather cooperating as we are having an outdoor ceremony. As always, best to have a "Plan B" which we do. That involves cramming about 130 guests into an outdoor tent and doing the ceremony/reception all in one place. Luckily, climatology says that the likelihood of a "rainout" is very slim. The average temperature in Portland on September 3rd is 79 degrees. Our wedding will be in Oregon City which typically runs a degree or two warmer than Portland. The last 5 years have seen an average of about 82 degrees with nothing but sunshine.
It appears our hottest stretch of weather this year just wrapped up. It's going to be tough to see more triple digits the later into summer we get. We've entered a stretch of below-average temperatures with a lot more cloud cover now as we begin the second half of August. I'm wondering how long it will last and will it impact the wedding. Portland hasn't seen any measurable precipitation in 31 days but that's not even half of our longest stretch, which was 66 days set in 1967. The GFS model run is finally showing the first glimpse of what we might expect for September 3rd.
Here is the 18z (11 A.M.) snapshot on the 3rd. This is the 500mb chart, giving us an idea where systems are and might be headed. The wind barbs show a strong "on-shore" flow, air will be coming off the ocean, thus giving us a cooler air mass.A westerly flow in late summer typically means that we start off cloudy as the marine air surges inland. This is all behind a system that comes onshore a day or two before the wedding that may produce some rain. Models that predict cloud cover do not go out this far, so using the map above I would say that we are looking at a somewhat cloudy start to the 3rd. Does that mean it will rain?
Above is the graphical precipitation output from the GFS model for the 3rd. It leaves us high and dry around 12 noon on Monday. Numerical numbers also back the maps.
|192||Wed 08/29 06Z||61 °||58 °||58 °||NNW 4||SW 4||0.00||0.00||564||578||13 °||-12 °||1016||0 %|
|204||Wed 08/29 18Z||59 °||56 °||57 °||SSW 11||SSW 16||0.00||0.00||555||566||8 °||-16 °||1013||3 %|
|216||Thu 08/30 06Z||60 °||57 °||56 °||SSW 13||SW 20||0.01||0.00||552||564||6 °||-19 °||1014||10 %|
|228||Thu 08/30 18Z||58 °||57 °||42 °||W 7||W 11||0.06||0.04||551||566||5 °||-17 °||1018||44 %|
|240||Fri 08/31 06Z||58 °||57 °||33 °||NW 7||NW 9||0.01||0.01||553||571||5 °||-15 °||1022||15 %|
|252||Fri 08/31 18Z||59 °||57 °||34 °||N 7||N 11||0.01||0.00||555||576||7 °||-13 °||1024||69 %|
|264||Sat 09/01 06Z||59 °||56 °||47 °||N 18||NNE 9||0.00||0.00||559||579||9 °||-13 °||1023||15 %|
|276||Sat 09/01 18Z||58 °||55 °||54 °||N 18||NNE 11||0.00||0.00||560||578||11 °||-13 °||1021||2 %|
|288||Sun 09/02 06Z||60 °||56 °||57 °||NNW 20||N 7||0.00||0.00||561||577||12 °||-13 °||1019||0 %|
|300||Sun 09/02 18Z||59 °||55 °||56 °||N 16||NW 11||0.00||0.00||558||575||9 °||-14 °||1021||12 %|
|312||Mon 09/03 06Z||59 °||55 °||54 °||N 16||NNW 11||0.00||0.00||557||575||8 °||-15 °||1021||12 %|
|324||Mon 09/03 18Z||57 °||55 °||45 °||N 11||N 11||0.00||0.00||557||575||8 °||-13 °||1022||25 %|
|336||Tue 09/04 06Z||59 °||55 °||39 °||N 20||N 11||0.00||0.00||559||576||10 °||-13 °||1019||26 %|
|348||Tue 09/04 18Z||58 °||55 °||39 °||N 18||N 11||0.00||0.00||558||574||9 °||-14 °||1019||2 %|
|360||Wed 09/05 06Z||59 °||55 °||51 °||NNW 20||N 9||0.00||0.00||558||574||10 °||-14 °||1019||2 %|
|372||Wed 09/05 18Z||58 °||55 °||55 °||NNW 16||NNW 11||0.00||0.00||556||574||9 °||-15 °||1021||5 %|
|384||Thu 09/06 06Z||59 °||55 °||56 °||N 16||N 11||0.00||0.00||559||576||10 °||-14 °||1020||8 %|
These charts give us a good idea of what ALL model runs are doing with temperatures. Each model runs several different parameters and these charts compile all the 850mb temperature outputs and compares them against average (green line). The red line is the average of ALL those runs, and the blue line is the operational (published) model run.
The first model is the ECMWF (European model). The red arrow indicates the 3rd. Not surprised to see such a wide variety of temperatures this many days out. However, the average of all the models looks to be pretty close to climatological average. One model goes as high as 22 degrees C, which would translate to 85-90 degrees F at the surface! The Euro also goes as low as 4 degrees C which would mean
Let's look at the GFS, my personal favorite model. September 3rd is indicated by the black arrow this time. GFS is thinking that things will be a bit cooler, indicated by all model averages (red line). Still plenty of variation and even more time to go for things to change. But this chart kind of supports what we saw on the numerical output with cooler than average temperatures on the 3rd.