Author | Lightnews

Amelia Urquhart 🏳️‍⚧️

@ameliaurquhart.bsky.social

750 followers 180 following 490 posts

(she/her) 🏳️‍⚧️🏳️‍🌈. Storm chaser and astrophotographer. Chase Archive team member. Cat mom. Oklahoma’s transgender menace. F 💞 ²⁰²⁴⁻¹⁰⁻⁰⁸.🌪️- 18 🌌 - 6 💻: https://github.com/a-urq 📸: https://amelia-urquhart.darkroom.com

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Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 10h

I work hard enough, I can give my code files silly names.

Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 1d

Hurricane Melissa's extreme Category 5 eyewall, rapid core disintegration over Jamaica, and subsequent rapid reintensification on approach to southeastern Cuba. Landfall is ongoing 20 mi/32 km west of Santiago de Cuba.

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Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 1d

The clock has just about run out on Melissa’s restrengthening period as its eyewall approaches the Sierra Maestra mountains. Even though it’s still extremely dangerous, I’m happy to see it didn’t intensify as much as I feared it would.

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Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 1d

www.desmos.com/calculator/o...

Amelia Urquhart 🏳️‍⚧️ on X: "https://t.co/6y3EudFFTF" / X

https://t.co/6y3EudFFTF

x.com

Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 1d

(4/4) This inward motion may cause the surface low to fill in, and the cyclone would reach a new balance in the absence of other forces. However, if the pressure falls from ascent over the sfc low outpace pressure rises from sfc convergence, Melissa may restrengthen rapidly.

Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 1d

(3/4) Think of a figure skater, or a professor holding dumbbells standing on top of a spinning chair. As either one brings their arms in, they spin faster. We may observe a similar effect with Melissa.

Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 1d

(2/4) Right now, the pressure gradient force is trying to crush air inwards. Since the centrifugal force is weaker due to relatively slow winds, a net push inwards exists. This will encourage inwards motion and, through the conservation of angular momentum, strengthening of winds.

Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 1d

Melissa is quite far out of force balance after reemerging from Jamaica. The sea-level pressure gradient as measured by recon suggests a wind speed of 104 mph, but their dropsonde only measured 78 mph. This disequilibrium may encourage rapid restrengthening, see below. (1/4)

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Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 1d

bsky.app/profile/amel...

Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 1d

I recommend anybody interested in donating uses the official website launched earlier today instead of the links I posted supportjamaica.gov.jm/donateq

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Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 1d

I recommend anybody interested in donating uses the official website launched earlier today instead of the links I posted supportjamaica.gov.jm/donateq

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Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 1d

American Red Cross: redcross.org/donate/donat...

American Friends of Jamaica: theafj.app.neoncrm.com/forms/afj-di...

World Central Kitchen: donate.wck.org/give/499865/...

International Medical Corps: internationalmedicalcorps.org?form=Melissa...

redcross.org

Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 1d

Category 5 Hurricane Melissa made landfall today near Black River, Jamaica with 185 mph winds and is currently re-emerging near Falmouth. If you have the means, I strongly encourage you to consider donating to a relief effort.

Direct Relief: donate.directrelief.org/give/647931#...

(more below)

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Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 2d

Upper-level cutoff low, slightly chilly, 85 MUCAPE is my favorite weather outside of chasing

Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 9d

Comet A6 Lemmon has gotten everybody's attention lately, but did you know there's a second comet in the sky right now? On Friday night, C/2025 R2 (SWAN) was faint and has no discernible tail, but that only let its fuzzy green coma shine more clearly.

Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 10d

At the time of imaging, it was about magnitude 4.6. It has started to produce something of a dust tail, but it’s much less that C/2023 A3 (Tsuchinshan/ATLAS) last year and that’s keeping its brightness down. Through my 10x50 binoculars it looked like a faint colorless smudge.

Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 10d

Comet C/2025 A6 (Lemmon) near peak brightness on October 17!

(see replies for visual binocular view)

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Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 23d

I took this shot this morning, from 5-7 AM with the full moon bearing down on me the whole time. I wasn't able to pull the faint tail out this time. In a way, that emphasizes the vivid green coma, a gravitationally unbound cloud of glowing gas emitted from the cometary nucleus.

Amelia Urquhart 🏳️‍⚧️ @ameliaurquhart.bsky.social · 28d

Full loop of the Fujiwhara effect between hurricanes Humberto and Imelda up to the present! I plan to update this with the rest of Imelda's lifespan as it drifts out of frame in 3-7 days.