Michael Fischer

Unfortunately the sky was indeed the limit. Catastrophic #Melissa is on track to be the strongest hurricane to make landfall in the Atlantic in 90 years. Just absolutely gutted for the souls in Jamaica.

#Melissa is intensifying very rapidly this evening. TDR structure is nearly perfect for a TC of this intensity. Incredibly symmetric, strong eyewall, and a deep, aligned circulation. The sky is the limit. Very scary situation.

And here we go again with Hurricane #Melissa. RI ongoing and expected to continue.

Ground-based radar imagery from Jamaica shows the core has continued to become better defined over the last six hours. A potentially catastrophic situation unfolding for Jamaica. #Melissa

#Melissa is about to undergo rapid intensification (RI). And I anticipate it will be quite explosive. A classic cyan ring on 37 GHz imagery from this GMI overpass at 1447 UTC.

Two tropical cyclones churning in the western Atlantic. Here in FL, it’s business as usual. The power of modern meteorology.

This is one of the best satellite signatures I have ever seen in the SW Atlantic (non-Gulf/Caribbean). #Humberto is up there with storms like Andrew, Dorian, and Irma in my eyes.

Ugh, I just realized a typo in my original post. This should read 45 kt intensification in the previous 12 h and 55 kt in the previous 18 h. Nevertheless, extreme RI is still ongoing.

Update: Hurricane #Humberto has intensified 55 kt in the last 12 h… extreme RI ongoing. Anomalous upshear convection is again a tell for subsequent RI. Thankfully the storm is well away from land for now.

One hypothesis is that because you usually have some degree of downshear convection in all TCs, anomalous upshear convection results in a greater projection of diabatic heating onto the azimuthal mean. This can aid evacuation of mass out of the boundary layer and intensify the primary circulation.

Anomalous upshear convection is often associated with rapid intensification in hurricanes. Here is a schematic from my dissertation and a recent snapshot of Hurricane Humberto, which is experiencing westerly shear. Although Humberto is fairly compact, its structure suggests RI is ongoing.

Hurricane #Erin looks poised to intensify, and likely rapidly.

With anomalously weak trade winds, the eastern Main Development Region of the Atlantic has rapidly warmed over the last two weeks. Models suggest this flow pattern should largely continue, favoring additional warming.

As of 6am CST 18 June #Erick is now a #hurricane & is likely starting rapid intensification, #RI, as a central dense overcast, #CDO, forms over the center.

Hurricane warnings in effect for coastal #Mexico from Acapulco to Puerto Angel & Erick forecast to be near major hurricane at landfall.

Stand Up for NOAA Research – The Time to Act is Now The AMS is a global community committed to advancing weather, water, and climate science and service.

The 2026 budget passback plan calls for eliminating NOAA Research, the scientific backbone that keeps weather forecasts, alerts, and warnings accurate and effective. This would have disastrous consequences.

Read the AMS statement, in partnership w/ @nwas.org: bit.ly/4cz2RtC

Cyclone Errol is an extremely powerful storm. IR brightness temps in the eye are quite warm for a core that small. Reminds me of Milton in the Atlantic last year. And for my northern hemisphere friends, I have rotated the IR pattern to be consistent with a positive Coriolis value in the 2nd image.

68,845,865.

That's how many individuals in the United States speak a language other than English at home.

Everyone deserves a chance to stay safe during disasters, and I will never stop advocating for that. Thinking of all the communities that are going to be affected by this change.

Thank you to UAH for the opportunity and hospitality during my visit. I had a great time talking about hurricanes and machine learning with the folks there. And a special thanks to @tcblers.bsky.social for the invitation and a great time in Huntsville!

2025 "Cone of Uncertainty" Update & Refresher Updates and summaries on tropical Atlantic activity... including easterly waves, tropical storms, subtropical storms, and hurricanes.

Here's my annual blog post about the NOAA National Hurricane Center's updated "cone of uncertainty". Hopefully there are some tidbits in there that are new to you! Atlantic hurricane season begins June 1 and ends November 30.
bmcnoldy.blogspot.com/2025/03/2025...

Probationary employees across @NOAA and the @NWS are being terminated today, including those in mission-essential roles.

My own wife is among them, essential to the Pacific Tsunami Warning Center's 24/7 critical mission of seismic monitoring and tsunami prediction to protect the public.

Uh oh. Zelia is explosively intensifying at this point. The enclosed pink ring in 36 GHz imagery is typically a signal only seen in extremely intense TCs or those about to be extremely intense.

Off the northwest coast of Australia, Cyclone Zelia appears to be intensifying quite quickly. Some of the hurricane guidance brings the system up to the equivalent of category-5 intensity before landfall. Hopefully that’s overly aggressive.

Just feel like I’m stuck in a nightmare that I’m not waking up from. What was egregious yesterday is tame today. When will it stop?

To summarize: RI tends to occur in vortices that are anomalously tall and narrow and in TCs with anomalously deep convection in the TC inner core. We hypothesize this helps evacuate mass out of the boundary layer, leading to the inward advection of angular momentum surfaces.

Based on those purple boxes above, we compute a metric of "vortex favorability" for RI. When plotted versus a metric of environmental favorability (smaller values of the "ventilation proxy" here), you can see RI occurs preferentially in certain vortex structures and environments.

It turns out that the anomalous TC structure (relative to TC intensity) is closely related to the rate of intensity change. For example, here are composites of the observed and anomalous azimuthally-averaged tangential wind and vorticity for each intensity change group.

One problem: TC vortex and convective characteristics are closely related to TC intensity.

Our approach: Normalize these characteristics and explore the anomalous aspects. For example, here are standardized anomalies of azimuthally-averaged tangential wind for two cases.

Here, we use TC-RADAR, which is a collection of over 1,100 airborne Doppler radar analyses of TCs sampled by NOAA aircraft over the last three decades to answer this question. We compare rapidly intensifying (RI), slowly intensifying (SI), and non-intensifying (NI) TCs.

Are rapidly intensifying tropical cyclones associated with unique vortex and convective characteristics? Abstract The largest tropical cyclone (TC) intensity forecast errors are typically associated with episodes of rapid intensification (RI). Here, we explore whether TCs that undergo RI are associated w...

"Are rapidly intensifying tropical cyclones associated with unique vortex and convective characteristics?" Well, you can find out more here: doi.org/10.1175/MWR-...

I'll summarize in the thread below.