Sebastian Harkema

Northern lights visible in Huntsville, AL!

A spectacular "cold wake" is evident along former-hurricane Erin's track. This is a normal feature caused by strong winds upwelling/mixing cooler water from below. Erin was not only very intense but also very large, which also helps with the upwelling. The water temperatures will gradually recover.

Welp, I just taught my first class ever! I'm excited to teach undergraduate and graduate students about natural hazards and their societal impacts.Thank goodness, it was syllabus day because I finished the class 40 minutes early. Here's to a good semester.

The NWS is soliciting comments through January 26, 2026, on the potential utility of Bluesky in the NWS mission. Bluesky is a social media platform that can provide a way for the NWS to share posts providing additional information that is complementary to official NWS products and outreach information. For a limited time, NWS will be engaging in a prototype activity to examine the potential utility of this social media platform to support operations. This prototype effort will utilize a national NWS Bluesky account, with posts being publicly visible via the following NWS Bluesky account page: https://bsky.app/profile/nws.noaa.gov . Additional information on the prototype use of Bluesky can be found at the following link: https://nsdesk.servicenowservices.com/api/g_noa/nwspc/res2/d664da9797aa62 148881bb7de053af4f The prototype period will last approximately through January 26, 2026. Based on the findings, NWS will determine whether to continue to pursue use of Bluesky at field offices. If NWS decides to pursue use of Bluesky and offer this service on a more consistent basis, another Public Information Notice announcing an experimental implementation date will be sent. Bluesky content and response to real-time comments will be provided on a time-available basis. Users should not rely on this service as the primary means of receiving NWS information about hazardous weather conditions. Users should tune to NOAA Weather Radio All Hazards (NWR) or local/national media sources for the latest critical information. NWS alerts and warnings are also available on the official NWS website:

The NWS is doing a test run of using Bluesky.

www.weather.gov/media/notifi...

I'm pretty sure I just saw a plane get struck my lighting taking off from Huntsville International Airport.

Three fights in the first 9 seconds of the game! #USAvsCAN

Three inches of snow so far in Huntsville, AL #alwx

Map of thundersnow from 5 January 2025. A total of 2496 GLM flashes were classified as thundersnow.

While many people were watching the snow accumulating, the Geostationary Lightning Mapper was busy observing #thundesnow. This is just a friendly reminder that #thundersnow is much more common than you think. 🧪

Geographic map of thundersnow from 05 December 2024.

Now that's a lot of #thundersnow from 5 December 2024. I've had family/friends in Michigan reach out to me and say they thought they saw/heard it 🧪

This is grate 🤣

So if the Department of Education is scrapped with the next admin, does that mean student loans are also scrapped? I'm asking for 40+ million friends...

Yes, feel free to save the 1st graphic as I personally produced it. I just ask that I'm credited for it.

Geographic map of the Great Lakes showing days since the last satellite observation regarding sea surface temperature.

The NASA SPoRT sea surface temperature plot looks spotty owing to the multi-day blending methodology. This product blends 7 days worth of satellite data to reduce gaps caused my persistent cloud cover which is extremely common in the Great Lakes during the winter.

Geographic map of thundersnow that occurred on 29 November 2024

Geographic map of sea surface temperatures of the Great Lakes on 29 November 2024.

The Great Lakes and Northeast regions have been experiencing a plethora of #thundersnow flashes and lake-effect snow. This is caused by cold arctic air moving over the relatively warm waters of the Great Lakes, as shown by the NASA SPoRT SST product. 🧪

Thanks for the validation data point! @wxkaitlynj.bsky.social

Geographic map of thundersnow detected om 20 November 2024.

No thundersnow was observed yesterday. However, all the snowfall images on here have brought me a lot of joy!

Geographic map of a single thundersnow flash in Wyoming on 16 November 2024.

Yesterday, a single thundersnow flash occurred in Wyoming. That's still one more than I've observed... #WYwx

Thank you! Currently, my algorithm runs internally. But I'm pushing these summary plots to a public facing server. I'll DM you the link if you're interested. Otherwise, I plan to continue posting the summary plots here everyday.

Geographic map of thundersnow detected on 15 November 2024.

Looks like California and Nevada observed the most thundersnow yesterday. #CAwx #NVwx

Post a picture you took (no description) to bring some zen to the timeline.

Welcome to Bluesky! #LGRW

Geogeqphic map of thundersnow observed on 14 Nov 2024.

Yesterday, GLM detected 30 thundersnow flashes in Northern California in a relatively small area. #CAwx 🧪

Geographic map of thundersnow that occurred on 13 November 2024.

Daily thundersnow summary for 13 November 2024. It looks like Colorado was the winner. 🧪

Apollo 12 is one of the reasons we have the lightning detection capabilities we do.

After the rocket was struck and "Flight, try SCE to AUX", a lot of research was focused on forecasting and detecting lightning.

Now we detect more than 2 billion lightning events around the world each year. 🧪

Map of thundersnow flashes observed from GLM-East within continental United States on 12 Nov 2024.

Thundersnow flashes that GLM-East observed on 12 November 2024. These flashes were classified by an algorithm that I developed as part of my masters thesis (6 years ago). Going forward, I'll be posting daily summary maps similar to this.

It's 6:45a, and my polling place has a line halfway around the building already. I've never seen anything like this before in Huntsville, AL! #YourVoteMatters

My thoughts on the Lions/Packers game so far: What if this rain was snow instead?

Some things can beat it, but updated code working flawlessly the first time is pretty high up on my feels good list.

Finally made the switch #wxtwitter! Lightning, thundersnow, and winter weather are my research passions. Yet, I'm warming up to sea surface temperatures and oceanography.