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Spring 2025 Banter


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1 hour ago, Wannabehippie said:

Spring has sprung. Weather pattern seems to be in full spring mode now. Interior sections of the tri-state area might see some really warm conditions on Saturday. Everyone ready for spring weather?

No

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15 hours ago, jm1220 said:

Skynet's drunk. Hide the vodka.

In all seriousness though most models are cold, enough for another couple/few freezes for most away from the city.

I doubt this verifies but we have seen snow in April.  I have no clue why people are shocked.

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Artificial Intelligence (AI) has garnered significant attention this winter and early spring in forecasting. Multiple AI initiatives are ongoing. In some cases, such as forecast 500 mb patterns, AI has shown improvement over the best-of-class operational ECMWF model.

One area that has not garnered as much attention is longer-range forecasting. Can AI make advances that push the frontiers of long-range forecasting? Chaos and non-linearity become more important as one expands the forecasting timeframe.

To take a closer look, I constructed some AI models to forecast the coming April. The AI-generated standard error and coefficient of determination hint at a large improvement over linear forecasting techniques. I say "hint," because I remain cautious about a hindcasting problem where things look good against past data only to break down in an actual forecasting situation. Consider, for example, the initial promise and more limited impact of using the Siberian Snow Advance Index (SAI) for winter forecasting.

I will share the results here for New York City (Central Park).

April 2025 AI Forecast:
Monthly mean temperature: 53.7°
Monthly maximum temperature: 84°
Monthly minimum temperature: 35°
Monthly precipitation: 4.32"

Those are equivalent to ensemble means. Some additional information:

Monthly mean temperature:
Below 52°: 17% trees or members
Below 53°: 41% of members
54° or above: 51% of members
55° or above: 28% of members
56° or above: 4% of members

image.png.196c3ecf446ec336dadbbf122b50cab7.png

This indicates that although somewhat more members show an above normal temperature, the smaller number of cool members are sufficiently cool to skew the overall average.

Monthly precipitation:
Below 3": 25%
4" or above: 61%
5" or above: 21%

Monthly Snowfall:
No measurable snowfall: 86% of members
Trace of snow: 13% of members
Measurable snow: 1% of members

I also inquired about how many members showed an April freeze. 29% had a monthly minimum temperature of 32° or below.

1991-2020 Baselines:

Monthly Mean: 53.7°
Monthly Maximum: 83°
Monthly Minimum: 33°
Monthly Precipitation: 4.09"
Monthly Snowfall: 0.4"

Comparison: CFSv2 Forecasts:

image.png.e38f55d24bf3a7645ae59379ba35b4e5.png

image.png.d43521f158a964c8ccbc3166b4f1c27c.png

Miscellaneous:

The AI model suggested that both Phoenix (above normal on the CFSv2) and Boston (normal on the CFSv2) would be above normal with April mean temperatures of 74.1° and 49.4° respectively. The AI model also suggested that Phoenix would have an April monthly maximum of 100° (range of scenarios: 97°-105° with 47% of members at 100° or above). In terms of rainfall, the mean forecast for Phoenix was 0.22" (normal). 33% of members showed no measurable rainfall; 67% had measurable rainfall; 28% had 0.25" or more; 13% had 0.50" or more; and, 8% had 1.00" or more.

My expectation:

I am agnostic about the AI forecasts. Aside from my own thinking that an April freeze is unlikely and that NYC has very likely seen its last measurable snowfall, I have no strong views about the possible outcomes. I note that this time around, the AI forecasts seem to be broadly in line with the CFSv2 ideas. 

Outcome:

The outcome will be verified at the end of the month.

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A reminder to enter April forecasts in contest ... 

Don, I wonder if contest consensus is a hidden form of AI? As you know, contest consensus in past years has generally beaten random (30-year avg) by an average of 0.5 to 1.0 F and as long as I have been tracking, also beats persistence (previous month anomaly) by an even larger amount. Not saying we have the 10-15 most skilled forecasters on site in contest, but even those we do have almost all beat normal. Our most skilled long-term (yourself, wxallannj, RodneyS) average 1.0 to 1.5 F errors per month ... less skilled regulars average 1.5 to 2.0. Will AI get even that good?  

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1 hour ago, Roger Smith said:

A reminder to enter April forecasts in contest ... 

Don, I wonder if contest consensus is a hidden form of AI? As you know, contest consensus in past years has generally beaten random (30-year avg) by an average of 0.5 to 1.0 F and as long as I have been tracking, also beats persistence (previous month anomaly) by an even larger amount. Not saying we have the 10-15 most skilled forecasters on site in contest, but even those we do have almost all beat normal. Our most skilled long-term (yourself, wxallannj, RodneyS) average 1.0 to 1.5 F errors per month ... less skilled regulars average 1.5 to 2.0. Will AI get even that good?  

Consensus often does better than most forecasters on a consistent basis. It will be interesting to compare the consensus with the AI forecast for Boston, New York City, and Phoenix once the picks are in. The AI forecast anomalies were: Boston: +0.8, New York City: 0.0, and Phoenix: +0.9. 

In probabilistic terms, AI was broadly in line with today's CPC idea of "equal chances" for Boston and New York City and "above normal" for Phoenix. In terms of rainfall, "equal chances" applied to NYC and Phoenix, but CPC had below normal precipitation for Phoenix.

image.png.1eab30c0eba9aa338c756b163547547d.png

Given the wet anomalies shown for Arkansas, I generated the AI forecast for Little Rock's April precipitation (6.96" vs. 5.59" normal value):

image.png.6a34de5c3d2d459de99d9215be644d56.png

Let's see how AI does finishes. Unfortunately, I didn't run the numbers for all of the cities, as I wasn't thinking of the contest at the time. I did look at a range of variable for New York City, as well as some variables for additional cities. Precipitation is tough to forecast. Maybe next month, I'll ask it for numbers for all of the contest cities to see how AI performs.

I personally think AI likely has a long way to go when it comes to consistently skillful long-range forecasts e.g., monthly numbers. Maybe the AI-generated numbers will prove consistently good. We'll see.

 

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Man combing through some of these old threads makes me happy I went into hibernation after the new year.  Cant believe how much things have changed in 10 years around here, seems like constant bickering and personal attacks.

I think some people need to enjoy this spring and summer weather coming and lighten up a bit, just sayin.

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