{ "number": 165, "headline": "December 26, 2023 Tuesday update", "standfirst": "A.I. modeling updates", "desk": "revision", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2023-12-26", "published": "2023-12-26T21:28:15.174000Z", "updated": null, "access": "free", "body_html": "

Winter storm continues to spin over the central Plains heading into Missouri on Wednesday. Looking at the NWS accumualation forecast and I\u2019m wondering if the snowfall shown in this HRRR 18z model simulation is legit on eastern Iowa.

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NWS Snowfall Accumulation forecast through the next 2-3 days. Light amounts generally.

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News:

This newsletter will rebrand as part of roll out of [WT] https://weathertrader.com in the coming weeks. Right now, the main hurdle is assembling all of the products that I have developed into a working interface. Monthly/yearly access will remain the same so I guess everyone will get access to professional products for $5/month. With ECMWF data becoming largely free in 2024, the market will quickly adjust downward in terms of cost for information. However, that means plenty of opportunity to provide value with unfettered access to ECMWF\u2019s real-time catalogue.

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I realize that these newsletter updates are huge, and may be filling up your inbox. I am tinkering with Substack\u2019s unofficial API to see if I can offload the images to cache or hot link to my own server at WT.

A.I. modeling update

During the Christmas weekend, I experimented with various A.I. global weather models to judge their capability of providing valuable and actionable forecast information that a professional user might need for commodities, energy or transportation.

First, let\u2019s jump in the time machine and go back to 1950. Obviously the Earth\u2019s climate was significantly cooler by about 1\u00b0C so no surprise to see the geopotential heights much lower in the tropics compared to the modern 1991-2020 climatology.

Pangu-Weather can easily recreate the weather from 7-decades ago, even back to 1940 from the ERA5 reanalysis or any other time period for which you have the requisite initial conditions (gridded data). This period in November 1950 is outside of the training data from the ERA5 used by Pangu-weather (1979-2020).

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What about Hurricane Sandy from October 2012. Absolutely. Pangu-Weather has no trouble dialing up the correct forecast track and timing of landfall 6-days in advance. Holy cow!

I do not know for certain if the success of this forecast is because it is within the training data [Pangu can see the answer key] or if it is legitimately capable of \u201cnailing Sandy\u201d like the Euro did in 2012 intensifying the so-called \u201cmodel wars\u201d between GFS and the ECMWF model.

This can be run with real-time data, so certainly out of the training sample. I am very impressed with Pangu Weather and GraphCast skill for large-scale features out to 10-days.

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Second, let\u2019s look at FourCastNetv2 from NVIDIA but extend out to 30-days. FourCastNetv2 can run very fast on a non-GPU system using 8-16 threads and finish this 30-day inference in 20-minutes.

At first glance, this forecast at Day 30 looks like any other conventional weather model output especially with details of the air masses. This is more akin to looking at one ensemble of the ECMWF EPS or GEFSv12 rather than the ensemble mean.

The various A.I. modeling systems produce fine vs. smooth output depending upon how they attempt to minimize RMSE error going through the forecast process.

Note, the climatology is maintained into January 20, 2024. I don\u2019t think this has much of a bias. Again, I am astounded.

FourCastNet v2 is completely open-source so the model and training weights can be used for commercial purposes. That is currently not the case for Google\u2019s GraphCast or Pangu-Weather. Not sure about FuXi.

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Wednesday Low Temperatures | December 27, 2023

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Lower 48 average low temperature is 31\u00b0F with only 71.5 Million population at/below freezing. However, there is 58% of the real estate of the Lower 48 below freezing, so a good example of why you should always population or energy weight for impacts.

Wednesday High Temperatures

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60s sneaking up into Delaware tomorrow. Cooler air behind the winter storm will slowly edge eastward across the Mississippi. What a pathetic excuse for an Arctic blast. Only 2 Million Americans in Lower 48 at/below freezing.

Temperature Outlook Next 2 Weeks

Greenland is cold but the Northern Hemisphere continents are very, very warm compared to normal. Wow those are huge anomalies. BUT, even with all that red on the maps, it averages out to 1.38\u00b0F above normal which is the lightest yellow on the color table if it were colored by only one value \u2014 the global average anomaly.

Week 1: December 26, 2023 - January 2, 2024 [EPS Mean 12z]

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Week 2: January 2, 2024 - January 9, 2024 [EPS Mean 12z]

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7-Day Precipitation Outlook

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The Rockies will be very dry over the next 7-days. Good to see continued precipitation extending into California. Again, this is still not snow in the Mid-Atlantic.

Snowfall Forecast Next 15-days

Probability of 3-inches or more falling from the ECMWF EPS 12z forecast across the Lower 48 in the next 15-days.

There is non-zero but not much better chances for snowfall across the Southern USA. Again, we can\u2019t really sound any alarm since this not actionable unless the values really increase to 50% or so.

We\u2019ll keep watching for hints of winter storm activity but the overall upper-level pattern is not conducive for intense winter storms aside from the cut-off low thing spinning and dying in the Plains. The jet stream is just not in any sort of mood to invigorate a \u201cbomb cyclone\u201d or Nor\u2019easter \u2014 and even if it did, there\u2019s no cold air.

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Median snowfall amounts from ensembles through 10-days is not going to satisfy very many folks looking to make a snowman or enjoy winter sports. Why? El Nino!

2024 Global Tropics

All quiet in the tropics. Ghost town across the Southern Hemisphere!

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Winter storm continues to spin over the central Plains heading into Missouri on Wednesday. Looking at the NWS accumualation forecast and I\u2019m wondering if the snowfall shown in this HRRR 18z model simulation is legit on eastern Iowa.

NWS Snowfall Accumulation forecast through the next 2-3 days. Light amounts generally.

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