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Storm in a tea cup: The weather thread

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  • Gangster Octopus
    replied
    I must admit that when I saw SB's post about an upcoming hurricane, I thought that I'd never heard of such a thing in California. Obviously there's nowt similar coming east across the Pacific.

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  • San Bernardhinault
    replied
    That is a very good point. The areas at the bottom of the San Diego River have a lot of homeless people who are very vulnerable to something like this.

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  • Incandenza
    replied
    All I can think about is homeless people living in places that could potentially become death traps with just a little bit of flooding. I haven't seen the City of Los Angeles make any announcements about trying to get people off of the streets and into shelters ahead of the storm, I doubt there's anything being done in the IE. I hope I'm wrong, but I can easily imagine people dying because of this.

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  • San Bernardhinault
    replied
    We're relatively well adapted to wind, and somewhere like Palm Springs particularly is. 60mph winds are windy but not at all unknown.

    It's the rain that's completely alien. Particularly in summer. But those numbers for the Coachella Valley are something else (I also saw a 4 inch rain forecast for Badwater Basin, but nobody lives there). I know that the washes are pretty wide in Palm Springs, but you have to think there's going to be some horrible flooding all the way down the communities in the valley. Nobody is really set up for it.

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  • ursus arctos
    replied
    First ever officia Tropical Storm Watch for Southern California declared by the National Hurrican Cebter

    https://twitter.com/weather_west/status/1692567308315599004?s=12&t=xvOireV8JOIS_CpbTtDBow]

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  • San Bernardhinault
    replied
    Hilary is now a category 4 storm. It's going to weaken a lot in the next 48 hours, of course. But the current NHC forecast has it still just as a tropical storm when it crosses the border. If my reading is correct, we've only had one tropical storm hit California since 1900. This is a massive outlier. It still looks like the worst of the impact will be in the deserts and mountains and not quite so much here closer to the coast.

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  • San Bernardhinault
    replied
    And there's a possibility of some interesting consequences. If the rainfall forecasts are right, something like 5 inches will fall on the Salton Sea and all up the Coachella Valley. 2.5 inches might fall in Death Valley. Because these are endorheic basins, the water will collect rather than run out. With this amount of water, the Salton Sea might even become marginally higher and less saline, and Badwater might flood properly.

    I'm guessing at this now, but it's different to normal here because this is a storm coming out of the due south. Most of our weather comes out of the west or southwest off the Pacific, and therefore the mountains act as a barrier. Which is why Palm Springs and Death Valley are so dry. But the topography is mostly lined up South/North in the basin and range, so the storm might pass along the valleys rather than lose all its water at the mountains.

    Anyway, I think it's unlikely to be very life threatening, just annoying for cyclists and golfers. But it's potentially fascinating.

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  • San Bernardhinault
    replied
    We might have a hurricane coming our way at the end of the weekend. More likely a post-tropical depression, but there are some models that have Hurricane Hilary still being Cat 1 as it crosses the border/makes landfall. It depends very much how far east it goes. If it tracks over Baja enough it will lose wind strength, but if it scoots up the coast it might still be hurricaney when it gets here.

    There has, I think I read, been a single hurricane making landfall in California ever. Usually a mixture of Baja and the cold currents from the north are enough to turn these things into tropical or post tropical depressions by the time they arrive, but Hilary is going to be up at Cat 3 or 4 in 36 hours and that might just be enough to maintain the storm through.

    Current track has the eye (or whatever they call it by the time it's post tropical) about 20 miles east of us, just where the mountains start getting big. Forecast is for maybe 2 inches of rain here (almost unheard of in Summer) and over 6 in some spots in the mountains.

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  • Moonlight Shadow
    replied
    Originally posted by San Bernardhinault View Post
    I'm not sure I fully accept that panic.

    First up, we're in an anomalous El Nino year.

    Second, medium term weather forecasting has always seemed a bit like a fool's errand and we never had a great track record at it.

    Third, we don't have a particularly long record of satellite data and therefore large area coverage and knowledge from which to make statistical extrapolations. It's not clear how much of the "old normal" we ever actually knew.

    Not disagreeing that the climate is clearly changing. I just think the author is putting too much credit in the previous ability and knowledge.
    El Nino is not fully on the way, the base state of the atmosphere has been La Nina until recently and there is nothing anomalous about El Nino, its effects upstream and downstream are well understood. It is not some unpredictable wildcard at all.

    Medium and long range forecasting is a game of probabilities based on multitude of drivers for numerical models and the human input is based on study of past weather, records go back a long way and a kind of pattern matching with previous years when the drivers were aligned with the current. Those analogues are becoming obsolete.

    Tamara is not the only one who has voiced that concern, i have noticed a number of experienced and indeed pro forecasters saying the same, there are changes that go beyond normal parameters, the heat anomalies at the ocean surface are wildcards for which we have no capacity to incorporate in our extrapolations. There is a phenomenal amount of weather data analysis and increasingly sophisticated models, ECM is now running a secondary model with an AI core for example and it will be interesting to see his performances over the next few years.

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  • Sporting
    replied
    Originally posted by Balderdasha View Post
    The UK's weather has always been a bit unpredictable like this, with the possibility of multiple seasons in one day, which is why we're famous for talking about it so much
    I get what you say, but I find that people here talk about the weather more than one might think.

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  • Balderdasha
    replied
    Today we've already had my daughter heading out to the shop in sunshine then getting rained on on the way home, then sunshine plus cloud for lunch outside, and now the wind is really picking up.

    Humidity this week is 90-99% overnight which is probably why I have a headache.

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  • Balderdasha
    replied
    El Nino isn't really anomalous. El Nino and La Nina occur every two to seven years on average and we used to be able to factor it into predictions.

    On a local level, I'm noticing that I have to check the weather report at least twice a day currently. I'm having to plan an indoor option and an outdoor option for each day with the kids because often I look at the weather report the night before and it claims it will be torrential rain, and then by the morning the report is showing blazing sunshine. I'm having to take suncream, sunhats AND light raincoats with us everywhere we go.

    The UK's weather has always been a bit unpredictable like this, with the possibility of multiple seasons in one day, which is why we're famous for talking about it so much (the variability, the unpredictability leads to lots of conversation opportunities), but this year seems to be even more erratic than most.


    ​​​​​

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  • San Bernardhinault
    replied
    I'm not sure I fully accept that panic.

    First up, we're in an anomalous El Nino year.

    Second, medium term weather forecasting has always seemed a bit like a fool's errand and we never had a great track record at it.

    Third, we don't have a particularly long record of satellite data and therefore large area coverage and knowledge from which to make statistical extrapolations. It's not clear how much of the "old normal" we ever actually knew.

    Not disagreeing that the climate is clearly changing. I just think the author is putting too much credit in the previous ability and knowledge.

    Leave a comment:


  • Moonlight Shadow
    replied
    There is a growing sense this year that the weather is becoming harder to predict, that past analogues are getting obsolete to predict future weather and long range signals that once provided a decent idea of weather patterns are being scrambled by forcings that we have never dealt with before (ocean heat being one).

    I quote someone from the Netweather forum below, Tamara and it might not make entirely sense to the most of you but you will get the concern in her post. As far as I am concerned, we have entered a new meteorological era, one of much greater uncertainty...

    Finally some fragile coherence has come to the expected synoptic pattern vs diagnostic wind-flow pattern with downstream ridging and Atlantic trough as far as the European sector is concerned - but there is so much extreme oceanic micro forcing around the globe (very much including the Atlantic) that is now testing medium range diagnostic analysis to the limit, let alone seasonal predictions.

    Seasonal wavelength changes and the increasing gradient differentials between the cooling at the pole and the lagged heat in the tropic with such anomalously extreme pockets of ocean heat look set to cause further chaos heading into autumn based on this additional superimposed forcing. Truly, all bets continue to be off and sitting back and trying to grapple with the global tipping point that is clearly underway is required.

    This summer has been a stark red flag for what is to come. Sensationalism this genuinely isn't.

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  • Sporting
    replied
    Originally posted by Sporting View Post
    Pretty constant temperatures here recently and forecast, too: highs around 31º, lows of 24º.
    The forecasts didn't predict today's 45º. It's been er, hot.

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  • Satchmo Distel
    replied
    We normally get our tropical rain in the late afternoon but the higher than usual morning temperatures have led to a lunchtime downpour today.

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  • Discordant Resonance
    replied
    Similarly, 24° at present in Tralee.

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  • Evariste Euler Gauss
    replied
    Song for current Cambridge weather in recent context: Etta James’ “At Last”.

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  • Nocturnal Submission
    replied
    Ah, OK. Thanks for the clarification Moonlight Shadow

    The weekend after next, then.

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  • Moonlight Shadow
    replied
    To add, when the record was broken in July last year, the 850 hpa layer above UK was 25c. The sun was higher in the sky, the air humidity was very low and ground moisture was very low.

    Different situation currently, no record about to be broken

    Leave a comment:


  • Moonlight Shadow
    replied
    The temperatures you see are upper layers, roughly at 1500m asl, not surface temperature. It is a constant temperature with no diurnal variation and is much better computed by models. It's a good way to see a warm (or cold) front progression.

    Ground temperature can be extrapolated from these but lots of variables come into play including sun strength and position in the sky, ground moisture, air humidity and a few more.

    Add between 5 and 10 degrees to give you an idea

    Leave a comment:


  • Nocturnal Submission
    replied
    Originally posted by Moonlight Shadow View Post
    The GFS model is having a moment this evening (and it's not without support when looking at other forecasting tools)...A plume of burning hot air making its way to our shores. The through west of Ireland is acting as a pump for the hot air advection.

    Maybe....

    I might be misreading the map, but it's not really going to be "burning hot," even if it's accurate. It's only going to be mid-20s at best, with the Isle of Thanet perhaps getting up into the high-20s.

    Leave a comment:


  • Moonlight Shadow
    replied
    The GFS model is having a moment this evening (and it's not without support when looking at other forecasting tools)...A plume of burning hot air making its way to our shores. The through west of Ireland is acting as a pump for the hot air advection.

    Maybe....

    Leave a comment:


  • Sporting
    replied
    Pretty constant temperatures here recently and forecast, too: highs around 31º, lows of 24º.

    Leave a comment:


  • ursus arctos
    replied
    All the same storm system, as was the one the ad hocs encountered in Budapest

    The death toll in Slovenia could have been much worse

    Leave a comment:

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