Sunil Nagaraj

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Sunil Nagaraj

Sunil Nagaraj

@sunil_nagaraj

Founder of @weathersightio, a website to discover, create and share reliable weather statistics and charts. Software Engineer based in Silicon Valley.

Mountain View, CA Katılım Mayıs 2009
363 Takip Edilen233 Takipçiler
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
One of our more ambitious goals is to build a publicly available 'hazards database' bottom-up. We have improved our capability to detect extreme weather by reducing false positives and expanding coverage. We want to annotate them with actual events and keep it updated. Most of all we want the dataset to be usable and easily accessible. There is still a lot of work ahead. If you have ideas or feedback, DM or leave them in the comments.🙏 #hazards #weatheranalytics
weathersight@weathersightio

The worst of the South Asian Monsoon is usually over by September*. Here is a look at extreme rain days on an absolute scale - those with more than 200mm(left) and 100m (right) in 24 hrs. Recently, Cox's Bazaar in Bangladesh recorded over 600mm in 48hrs leading to widespread flooding. Can you identify the other locations on the map that led to widespread floods? 👇

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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
“globally. We estimate that the land surface temperature increases by 2°C on average after the start of operations of an AI data centre, inducing local microclimate zones, which we call the data heat island effect. We assess the impact on the communities, quantifying that more than 340 million people could be affected by this temperature increase” - the paper.. This sort of mistake/ poor numeracy is sadly rampant.
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
You can see different views of the same data Fig 1. Observed Value of KPHX . Fig 2. Delhi winter as seen with percentiles. tinyurl.com/dailycompphx
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
To get a sense of how abnormal of this SW heat wave, can we compare them to others? Here is an attempt to look at the normalized heatwaves of 2024 in San Jose, CA, Phuket and Vientiane. If you have others you want to compare or look either percentiles or actual values, check the comments below. 🧵 #heatwave
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weathersight@weathersightio

Alaska and much of the US SW 2026. While the cold was quite not record-breaking (and definitely not as widespread) it has been as persistent in Fairbanks (Fig 1) as the record breaking heat, as in Phoenix (Fig 2). One way of understanding the persistence and severity is to plot their daily normalized deviation from mean. #uswx #swheat

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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
@DonSuth89069583 I built something to visualize streaks. e.g. PHX vs Vientiane (Apr 2024) . I will post more later, but getting a percentile, z-score view might let us compare across geographies/timelines?
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Don Sutherland
Don Sutherland@DonSuth89069583·
#Junction, #TX has reached 90F (32.2C) for the third time this month. That breaks the November record of 2 days from 2017. Two of those days occurred during the second half of November this year. #txwx
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
@WeatherProf You are likely to be correct - more extremes are included as you add more history. Let me include those. Can you make this tool available somewhere? (It's cool and useful)
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Jeff Berardelli
Jeff Berardelli@WeatherProf·
You are probably right. My calculator is conservative it seems. Using Gaussian and SFO is based on a shorter record than many other stations. It says return period is 450 years. But I’d welcome your input on the calculation. There was an 85 earlier in the record so 89 may simply be not high enough for a higher sigma ?
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
@down2earthindia - The visuals below might have helped the article make the point of warming winters. Unfortunately, I don't have adequate data for Bikaner and Churu to make the statistical case (only ERA5 grid with bias). Can you petition IMD to make historical data freely available?
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Down To Earth
Down To Earth@down2earthindia·
Death of winter: Rajasthan’s cold season is fading — and farmers are paying the price Fewer western disturbances, almost no winter rain, and rising temperatures are shrinking the season. Crops are withering, yields falling by up to 30%, and livestock are falling ill as climate patterns shift. downtoearth.org.in/climate-change…
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Anthony Farnell
Anthony Farnell@AnthonyFarnell·
The only place on the planet with sustained below seasonal temperatures this week, is right here in Canada.
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
Much of the Bay Area (and most of the West US) endured a 5 day period of extraordinary heat in early spring, not seen since Apr 1989. Salinas, CA typically sees heat-waves in Sep-Oct, but Mar 16-20 2026 was among the top 50 heatwaves in the last 80 yrs - easily its earliest #salinas #springheat
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
@DonSuth89069583 @votewarren Do you have similar stats for other high/low desert locations? Like Palm Springs, Las Vegas, Tucson, ABQ etc? (with similar POR of course)
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Don Sutherland
Don Sutherland@DonSuth89069583·
@votewarren Almost 25% of #Phoenix’s daily record highs have been set since 2020. If ties are included, that figure exceeds one-third of days. Records go back to August 1895. That’s about 5X above an equal distribution of records. It’s highly disproportionate.
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
@wxjerdman Truly remarkable. Averages ~+5F more than any previous heatwave during Nov-Mar. And is now worse than the 5-day 1989 early April heatwave.
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Jonathan Erdman
Jonathan Erdman@wxjerdman·
Redwood City, CA has reached the 90s for five straight days since Monday. Prior to Monday, they had never recorded a single 90˚+ high in March dating to 1930. #heatwave
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
Not how I remember it. Hep A was more prevalent (anecdotal) and contractable. BTS was unpredictable and crowded. Teens now use Metro which is way better. Weather - see 1998, 1990 (hot,muggy)/1997,1998 (heavy rain). Power cuts/load-shedding was frequent. Is that still at thing?
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
Interesting you frame it that way [1/p] vs saying in a 100 yr period there's a 2.18% chance. 1-(1-p)^100 . Also how has the distrib itself shifted over 30 yr periods? (My data shows: 3.27σ ('61-'90)[2500yr] to 3.2σ('91-'20)[~2000yr]. How did the viewers respond to 'return period'?
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Jeff Berardelli
Jeff Berardelli@WeatherProf·
105° in #Phoenix today has a return interval of ~4,000 + years in March based on the historical record. It’s plotted against the highest March temp in each year back to 1896. The gray dot right under it is yesterday, otherwise the 105° would look even more errant. Obviously though this type of rogue heat is much more likely now-a-days due to climate change. #heatwave
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
@down2earthindia Is this because of a changing climate? Or is our collective memory imperfect? I looked at some data for 'first week of spring with rain' - not much of a trend. Also '9.4mm' - wettest in 3 yrs is not much of an argument for the position you take. WD's occur through March.
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Down To Earth
Down To Earth@down2earthindia·
Photo of the Day: Delhi wakes up to rainy morning on Spring Equinox 2026 In today’s time of changing climate, the distinction between seasons is largely starting to blur Photos by Vikas Choudhary downtoearth.org.in/climate-change…
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
@WeatherProf Yes, waiting for the > +21°C - I had noticed one around the Black Sea (Samsun, Turkey last year. So SD,NE etc are locations with the highest Tmax σ (~7.5-8°C) for the month of March. (left: world Tmax σ, right: zoomed in to central US) #spring
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Jeff Berardelli
Jeff Berardelli@WeatherProf·
Tomorrow will be… checks notes… 42°F above normal near Omaha Nebraska! (High of 90°+)
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Sunil Nagaraj
Sunil Nagaraj@sunil_nagaraj·
@TheGlobalWarmer Why all the hyperbole. It's quite remarkable as is. Apr-Oct have all seen temps > 90F for SF Downtown. So *not* hot enough to beat summer records.
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The Global Warmer🔥🌏 🔥
The Global Warmer🔥🌏 🔥@TheGlobalWarmer·
San Francisco just hit 90°F… in MARCH. This didn’t just break records — it obliterated them:
• +3°F above the all-time March record
• +12°F above the daily record
• Earliest 90°F by >2.5 weeks This is the kind of heat that would set records in SUMMER, not early spring. Completely absurd. 🌉🔥 #CAwx #ClimateCrisis #GlobalWarming
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Don Sutherland
Don Sutherland@DonSuth89069583·
Parts of the West again fried in monthly record heat today. Some locations surpassed April marks.  A U.S. national March record of 112F (44.4C) was set at four locations.  Select monthly records during the epic March 17-20 #heatwave follow.
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@DonSuth89069583 @WeatherProf @down2earthindia @AnthonyFarnell @votewarren @elonmusk @BarackObama @taylorswift13