Thursday, July 10, 2008

Divergent forecasts

It is hard to make plans for the weekend when the two major forecasts can't agree.

As of 10 am on Thursday the temperature predictions are similar for the weekend, but the probability of precipitation has some major differences:


POP values

Saturday

EC - 60%
WN - 20%


Sunday

EC - 60%
WN - 20%


Monday

EC - 40%
WN - 10%


EC=Environment Canada
WN=The Weather Network

5 comments:

Anonymous said...

Weather Network's forecast usually corresponds [better] with EC by the afternoon. I guess EC updates the KW model earlier in the day. Check WN around 14:00 this afternoon.

Anonymous said...

Looks like I was wrong. Oh well, another day, another theory, another possibility of rain...

Anonymous said...

It would be interesting to track, which weather service has the best overall accuracy. Sometimes it seems that they look out their window and just guess.

UWMet said...

I'm a UW grad who is currently a meteorologist. If you think we have models for specific cities you're quite wrong. A forecast is done by usually looking at 3 models (GEM, NAM, GFS), analyzing them and coming to the best solution. New model runs aren't available until 11 am / pm EDT or 10 am / pm EST. TWN's forecast actually comes out around 3 pm and EC's comes out at 3:30 pm. Each company doesn't care what the other has in the forecast. EC's forecast is heavily weighted on just 1 model, the GEM. Forecasts of weather more than 48 hours out are for the most part.

As for this weekend the low POP's for TWN are due to the weather during the afternoon expected to be fair. A cold front comes through Saturday evening and into Sunday Morning which will certainly bring rain in the overnight. EC's POP's are likely based on that.

uwmet said...

I forgot to mention forecasts in the long range ( Day 3 and onward ) are only done on night shifts and significantly less attention is paid, due to time constraints.