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300 meters resolution SF Bay Area Forecast

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Re: 300 meters resolution SF Bay Area Forecast

#51

Post by hadlock »

Waterluvian wrote: post #12

A few thoughts from a geographer (be prepared to shoot me): - Basically every comment is wowed by this, but nobody questions what the accuracy is. I, too, can Krig interpolated surfaces to any resolution. - off-nadir view doesn't seem to offer much - We've been dealing with janky tile loading for like 20 years now. I really hope we'll get a much smoother approach for viewing these tiles as they load. The dissolve tra…

Few thoughts as a sailor in the SF Bay area.

- Accuracy seems at least somewhat correct.That wedge shape you see in the late afternoon sailors call "the wind engine". Local sailing magazine Lattitude 38 has a special PDF that talks about doing a sailing trip around the bay accounting for this local wind phenomenon.

Correct stuff:

- The SF waterfront, out to the edge of the piers is mostly calm which is correct

- Berkely, Oakland, Emeryville getting blasted late afternoon is correct

- Back side of treasure island, immediately to the east is much lower than the west side, particularly near clipper cove

- Vast majority of alameda estuary is dead calm, that's correct for this time of year

- There's a big blast of wind between Daly City and OAK international where there's a gap in the mountains

Weird stuff:

- Most noticable, is the wind is still strong up to and south of the bay bridge. The bay bridge has been described by many as "a wall" when it comes to the wind. There's a drop off but it's not in line with the bay bridge. At all. at least 45 degrees off from true wind speed.

- There's a very windy patch between golden gate coast guard station and belvedere, it's usually really patchy wind here but I guess if the wind direction is just right it'll blow there

- Pointe Bonita (lighthouse on the west side of gg bridge about 2 miles, north coast) they are modeling the gap in the rocks there and you can see it funnel through which is neat

It's a cool visualization though, gives you a great idea of where the wind is, and more importantly where it won't be. There are a bunch of races that start in the bay and head south towards Santa Cruz and Monterey so it's nice to better visualize where the wind just dies off on the coast as it skips over the mountains.

Anyone who wants to see what the wind is like in the bay I recommend reaching out to YRA.org they can put you in touch with a boat who needs crew most likely. There are races 4-5 days a week through november all around the bay. It is modeling a distinct drop off of wind speed on the south side of the bay

Re: 300 meters resolution SF Bay Area Forecast

#52

Post by lbrindze »

mturmon wrote: post #35
lbrindze wrote: post #31

Earlier quoted context omitted.

Given this is in the SF bay there a number of high quality observations that you can use to validate the forecast skill (unlike India and Africa). I have not bothered doing this here since… well that’s too much like my day job. I’m always excited to see new forecast products, generally. If I were to guess (as an above comment did) it looks like they are applying some dynamic downscaling on top of either a custom WRF…

The website claims to be using DL which may mean less of a model-centric approach? The expertise of the people at the top of the organization, on this problem, seems a little thin, TBH. And, no stated validation results at all? Without such details, this is just marketing. It would be interesting to see how this behaves for longer prediction times and across a range of difficult forcing conditions off the ocean in th…

I agree, this generally left me feeling skeptical. I know of Luca Delle Monache on the advisory team, through colleagues who have researched under him at Scripps and they spoke highly of him. But yes, there is a lot left to the imagination here.

With regards to the sfbay specifically I used to work with a fairly high resolution wind model for the bay (this was a more traditional dynamic based simulation) and it worked pretty well overall, but every time a storm blew through it would crash. This ultimately had to do with the relatively steep terrain in the bay specifically (and the physics configurations we were using in the actual model).

Even if they are using DL they still need initial and boundary conditions. As I said there are a ton of weather stations around so I could imagine a DL type approach that looked at terrain elevation, and recent + historical observations to initialize a forecast, but I still imagine that boundary conditions would have to be provided by nesting this in a larger model somehow. Then again, I'm not a DL expert at all so there are probably some newer stuff in this field that I'm just out of date on.

Its really expensive to run your own dynamic forecast model, at a refresh rate acceptable for an actual forecast, at this resolution. That's why I suspected its taking existing weather models and downscaling them with DL techniques, but I can't really know just by looking.

Re: 300 meters resolution SF Bay Area Forecast

#53

Post by lbrindze »

lispisok wrote: post #27

If I had to guess they are running the WRF model [1][2]. The AI part is post-processing the model output. With a fair amount of reading the manual anybody can run their own WRF. WRF scales from running on a laptop to supercomputers with 1000s of cores. [1] https://www.mmm.ucar.edu/models/wrf [2] https://github.com/wrf-model/WRF

sure anyone can do it, but it takes a lot of computers to do it at a reasonable refresh rate. HRRR is 3km and available for free. no super computers required by the end user. then you can apply what ever AI/statistical downscaling you want without having to try and run a better/more reliable forecast than the NWS

Re: 300 meters resolution SF Bay Area Forecast

#54

Post by CalChris »

issa wrote: post #48
asdff wrote: post #34

This needs to be done for more cities in California, especially Los Angeles with its huge geographic area and all the diverse micro climates contained within. Sometimes the weather changes more than 15 degrees in half as many miles from the coast. It therefore doesn't make sense to e.g. check "weather in LA" when its going to be somewhat wrong most of the time depending on where in LA you happen to be, since the litt…

I feel like you could make a whole movie about the weather in LA. It would change your life. Twice.

Not weather, sun, sun, sun, sun, sun!

Re: 300 meters resolution SF Bay Area Forecast

#55

Post by anyfoo »

Growing up in Germany, before I moved to the Bay Area, I was wondering why weather apps and widgets were so prolific. Sure, knowing the forecast for next weekend was nice, but for anything closer I'd just get out of bed and look out of the window. That would pretty much tell me what weather it is, and it would usually change just slowly over a few days or so.

Then I moved to the Bay Area, and weather does not only change quickly, it may also be vastly, vastly different just a short distance away. Temperature differentials of 10°C or more within just 40 miles are interesting enough that it's a frequent topic of conversation with friends in Germany.

Everything suddenly made sense. The weather widgets. The hoodies: Easy to put on or off.

Re: 300 meters resolution SF Bay Area Forecast

#56

Post by CalChris »

duanem wrote: post #47
samvher wrote: post #18

Earlier quoted context omitted.

This seems to be a thing with weather models more generally. Somewhat relatedly, I've spent quite a bit of time evaluating weather models for use in India and Africa, and while predictions are easy to find, validation results for the predictions are very hard to find. And when you do find them, the results are pretty poor, with many models performing worse than if you would say "predict temperature on date X to be th…

I've been working with weather models for 10 years and I often get asked "How accurate is X?" or "Which model is more accurate?" Many people think "accuracy" is a single number or a single thing - it is more complex than this and depends on your needs. This chapter on Numerical Weather Predictions [0] is great, especially the section on "Forecast Quality and Verification" (p777). The eye-opener for me was "Binary/Cat…

> other models might be better in certain regions

The US Navy's COAMPS model is good for littoral regions.

Re: 300 meters resolution SF Bay Area Forecast

#57

Post by anyfoo »

anyfoo wrote: post #55

Growing up in Germany, before I moved to the Bay Area, I was wondering why weather apps and widgets were so prolific. Sure, knowing the forecast for next weekend was nice, but for anything closer I'd just get out of bed and look out of the window. That would pretty much tell me what weather it is, and it would usually change just slowly over a few days or so. Then I moved to the Bay Area, and weather does not only ch…

Another anecdote: In the South of Germany at least, long stretches of sunny days are often followed by sudden thunderstorms with equally sudden bursts of rain. That "fact" had been so deeply ingrained in me that it was subconscious. You'd have a careful feeling if it was hot for too long, suddenly you might find yourself running for the next awning to escape the torrential rain.

Sunny weather was a bit like building up a sort of pressure, that must release violently.

Took a while to let go of that feeling in California. It basically rains in winter, and does not rain in summer. Like, at all.

(Note that I moved away about a decade ago, climate may have changed in the meantime.)

Re: 300 meters resolution SF Bay Area Forecast

#58

Post by londons_explore »

Weather forecasts are so hard for a user to evaluate... Are you going to check it every day and remember how many days it was right or wrong?

Please can weather providers just publish a headline statistic of "Our rain/no rain one day ahead forecast is right 85% of the time. That is better than NOAA (80%), Met Office (72%) and weather.com (65%)."

Re: 300 meters resolution SF Bay Area Forecast

#60

Post by carabiner »

londons_explore wrote: post #58

Weather forecasts are so hard for a user to evaluate... Are you going to check it every day and remember how many days it was right or wrong? Please can weather providers just publish a headline statistic of "Our rain/no rain one day ahead forecast is right 85% of the time. That is better than NOAA (80%), Met Office (72%) and weather.com (65%)."

This is kind of the purpose of the "50% chance of rain" things. The process is called calibration and is usually done with linear regression, and it means that in historical forecasts, the actual outcome was rain 50% of the time. Surface precip is notoriously hard to predict, so this is what we've got right now.
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