Weather Chat Thread

Is El Nino On The Horizon?
( source: Weatherzone )

Some computer models suggest that El Niño could return next year, bringing an abrupt shift in one of our planet’s major climate drivers following three consecutive years of La Niña.

The graph below shows the most recent computer-based El Niño-Southern Oscillation (ENSO) outlook from the U.S. Climate Prediction Center (CPC) and Columbia University’s International Research Institute for Climate and Society (IRI).

The bars on the graph above represent the probability of La Niña (blue), El Niño (red) and neutral conditions (grey) occurring in the tropical Pacific Ocean during each of the next nine overlapping three-month periods.

The graph shows that La Niña has a 90 percent likelihood of remaining in place over the next three months. Neutral conditions then become more likely than La Niña from late in the Southern Hemisphere’s summer through until the middle of 2023.

Further into the future, this outlook suggests that El Niño becomes the most likely state for the Pacific Ocean late in the Southern Hemisphere’s winter in 2023. This is the first time in around three years that the monthly CPC/IRI outlook has favoured El Niño as the most likely category in the Pacific Ocean.

It is important to point out that the U.S. CPC and IRI use slightly more relaxed threshold than Australia’s Bureau of Meteorology for identifying La Niña and El Niño.

Also worth highlighting is that this outlook becomes less reliable the further it looks into the future, so predictions for the middle of next year should be treated with some caution. More reliable ENSO outlooks will become available early to mid-next year.

First 30-degree Sydney day in 279 days?
( source: Weatherzone )


It has been a long time coming, but this Sunday, Sydney could see its first day of 30°C or higher since February 21, as northwesterly winds drag inland heat over the harbour city.

If the predicted top of 30°C is reached, that would be a streak of 279 days between 30-degree days.

While a streak of that length is not unprecedented, it’s the longest period without a 30-degree day since 1992/93, when Sydney went 337 days without touching 30°C between Feb 23, 1992 and Jan 14, 1993.

A year without extreme heat

Sydney has had very little in the way of serious heat by Australian standards in 2022 to date, especially along the coastal fringe (the city's official weather stats are taken from Observatory Hill), at the southern end of the Sydney Harbour Bridge).

To date in 2022, there have been just seven days of 30°C or higher, with a hottest day of 31.9°C on February 1. The annual average is 15.5 days.

That's right, Sydney hasn't yet even touched 32°C in 2022 – a year in which London's Heathrow Airport topped 40°C (in July) for the first time on record.

Sydney has also thus far seen no 30-degree days outside January and February. As you can see on the chart below (which you can find here), at least one 30-degree day can be expected in each of March, November, and December.


The lack of hot days is of course related to all the rain Sydney has had this year.

Wet, cloudy days tend to make for cooler max temps, and the city currently sits on 2442.4 mm of rain for the year, which is a record, and is more than double the annual average of 1213.4 mm.

A surprising stat

With all that rain, and with so few days over 30°C, you'd expect Sydney's running average maximum for 2022 to be tracking well below average. But that's not the case.

Indeed, Sydney's average maximum for 2022 to date is 22.4°C, compared to the long-term average of 21.4°C through to the end of November.

The fact that Sydney is a full degree above the long-term average maximum in 2022 to date is a likely signal of the warming climate.

Sydney's average max temp is, however, running slightly cooler than the most recent 30-year mean (Jan to Nov 1992-2021) of 22.6°C.

We hope you enjoy the warmish weather due on Sunday, and indeed the dryish spell the city is currently undergoing. To date, November has been the second-driest month (after June) of a relentlessly soggy year.

Besides Maatsuyker Islands in Tassie, which area in Australia has very high windspeeds? Can you name a few?

greysrigging ?

Looks like two weeks later it still hasnt hit 30C.






The last 30C in Sydney was Febuary 21st.

I've found that most Davis Instruments PWS'es (my VP2 included) exhibit a moist bias in the mid-range RH values. This post explains why I have come to the decision to use an equation to correct RH/dewpoints for that.

I've conducted various tests over the weeks comparing my VP2 to a Kestrel 5500, and I have found that the VP2 consistently reads higher RH values in the mid-ranges, in the order of 4-5% in the 30-70% RH range. Keep in mind that there is a humidity offset of -2% on the VP2's part. While this error may not seem like much in many circumstances and doesn't change monthly mean RH/dewpoints much; in humid heat for example, this can throw off heat index values by several °F.

A couple of examples of tests I've done comparing to my VP2—granted a fairly small sample size, but I've compared quite a few times with similar results.

September 25:



November 28:



To test my theory, I then compared my Kestrel 5500 to New Bern ASOS in the afternoon of December 9, around 3:15 PM as a steady northeasterly breeze was blowing. Apologies for the shitty phone pics, but you get the idea:



There have been some WXForum forumers who have done a similar thing, and also found that their VP2 exhibited the same moist bias: www.wxforum.net/index.php?topic=32439.0

Based on this trendline, see pg. 6 (this rules out the possibility of a bad hygrometer on my part), I have worked on an Excel equation for correcting RH/dewpoints (this is only meant to be used for my own PWS, applying it to your own likely wouldn't work very well unless you're absolutely sure, as there is some variation in how much moist bias between units/sensors, and it also could be somewhat dependent on the climate, i.e. the moist bias might be slightly less if such a VP2 were always in a climate with lower average RH than my own); this also addresses the issue with RH maxing out in the 96-98% range with Vantage Pro2's in particular. I'm erring towards mid-range RH values slightly lower than what my Kestrel 5500 gives. The following polynomial Excel equation worked out to be approximately:

0.0037 * RH^2 +  0.62 * RH + 5.0172
If the output RH is above 80% but below 90%, then

1.05 * RH_adjusted^1 - 4.5
is included in the equation, to smooth out the transition between subtracting 0.5% below 80% RH but not at all above 90%.

This equation is only valid for RH above 15%; in very dry air, the bias actually decreases.

If we take the September 25th example, the corrected RH value would work out to be:

81.5°F/62.2°F = 52% RH = (0.0037 * RH² + 0.62 * RH + 5.0172) - 0.5 ≈ 46.8% RH ≈ 59.2°F dewpoint — very slightly lower DP than the Kestrel 5500 

If we take the November 28th example:

66.1°F/49°F = 54% RH = (0.0037 * RH² + 0.62 * RH + 5.0172) - 0.5 ≈ 48.8% RH ≈ 46.3°F dewpoint — virtually the same as Kestrel 5500

Some additional examples:

95/77°F = 56.3% RH = (0.0037 * RH² + 0.62 * RH + 5.0172) - 0.5 ≈ 51.2% RH ≈ 74.2°F dewpoint

70/65°F = 84.2% RH = (0.0037 * RH² + 0.62 * RH + 5.0172) - (1.05 * RH_adjusted¹ - 4.5) ≈ 83.2% RH ≈ 64.7°F dewpoint

If we take an example with saturated air:

68/67°F = 96.6% RH = (0.0037 * RH² + 0.62 * RH + 5.0172) ≈ 99.4% RH ≈ 67.8°F dewpoint (RH readings around the 97% range are about the highest I've seen for my VP2, and anything the equation gives a value above 100% will be counted as 100%)

Whole-month example for September 2022 (hourly-only data for ease of loading):

Raw - jsfiddle.net/ofkajqgb/

Adjusted - jsfiddle.net/hytw15kc/

KEWN ASOS for comparison - www.weather.gov/wrh/timeseries?site=KEWN&hours=72&units=english&chart=on&headers=on&obs=tabular&hourly=true&pview=standard&history=yes&start=20220901&end=20220930

Based on all this together, all current weather posts, monthly summaries, etc. will have RH/dewpoint values adjusted for the aforementioned moist bias going forward. Raw and adjusted RH/dewpoints will be in two separate columns for the Excel spreadsheets I post in monthly summaries. Raw RH/dewpoint values for my PWS may still be found in WU, CWOP and WeatherLink. Keep in mind that plant transpiration, proximity to bodies of water and evaporation from it still can significantly affect mean dewpoints (in my case, mine is right at the Neuse River and there is far more vegetation than any airfield so mean DP's for my PWS are still higher than KEWN (generally by 1-3°F during the day) due to the aforementioned factors (thus, the difference is legitimate), as well as less radiational cooling). Until recently, I didn't realize that WeatherLink has a setting for rounding temps and other data or reporting the decimal point, thus dewpoint data will be to the decimal point for current weather posts going forward. This is by no means an ideal solution, but hopefully adjusted for that, dewpoints and RH for my PWS will be closer in line to what would be expected from ASOS/AWOS systems, or any other properly calibrated hygrometers.

TL;DR and Conclusion: Shame on Davis Instruments for not using higher quality hygrometers (than Sensirion) and calibrating them properly. That being said though, among actual, quality PWS'es that can easily be bought by the average consumer, I still believe that Davis Instruments PWS'es are pretty good for the value for money, with accurate air temps and a good radiation shield.

After 9 straight days of mild gloomy sunless garbage, sure is nice to have a cold clear sky day today.

This right here is why I dont follow the Weather Network (article posted Dec 18, 2022): www.theweathernetwork.com/ca/news/article/health-threatening-cold-filters-onto-the-prairies-50-c-is-possible


They write in their article above that Canada has not had a -50C temperature in 8 years. A "Meteorologist" goes on video saying this as well in the article. And they have a map of the 'most recent -50C temperature" in different provinces.

Canada has recorded -50C at multiple stations in January 2022 alone.

If they mean't last -50C in December, also incorrect as there was multiple -50C readings in December 2021.

Their map is also completely incorrect with the three northern territories all recording -50C over the last few years.

Within the past "8 years', -50C temperatures were recorded in Canada in 2022, 2021, 2020, 2018, 2017.

What a joke.

Our 5 Biggest Overseas Weather Stories Of 2022
( source: Weatherzone )
www.weatherzone.com.au/news/our-5-biggest-overseas-weather-stories-of-2022/994584