Mona Hemmati

@monahemmati.bsky.social

Global TC Peril Lead @GallagherRe| Adjunct Associate Research Scientist @LamontEarth @ColumbiaClimate | Studying climate with a focus on #ExtremeEvents | Views are my own.

The report also includes a great analysis from @monahemmati.bsky.social that dives into ENSO / Tropical Cyclone relationships. In short, there's a lot of nuance and sub-ENSO phase variability that has real implications on not just storm frequency, but storm directionality for landfall risk. (5/n)

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*Busy* Monday for me at #AGU25 NH12B-05 11:12-11:22 Applying the Swiss Cheese Model to Wildfire Risk Management in the Built Environment TH15B 6-7 Town Hall Hurricane Katrina 20 Year Later then RUNNING to Atmos Science section Student/Early Career mixer to talk cat modeling 7-8:30

Today marks the official close of the 2025 Atlantic #hurricane season — a season defined by striking contrasts. From an unusually quiet peak to sudden bursts of extreme intensity, 2025 reinforced a critical lesson: a low storm count doesn't mean low risk.

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Last year, I experienced Cat 1 Hurricane #Beryl making landfall in Houston. It was both terrifying and fascinating—an intense reminder of nature’s power and how small we can feel in its presence. I can’t imagine what the people of Jamaica and other countries in #Melissa’s path are going through.

#Melissa is undergoing explosive intensification — winds have surged 50 kt in 24 hours, including 35 kt in the last 12! Jamaica faces a potentially catastrophic impact as the storm nears. And it’s not just the wind — the 4-day rainfall forecast is astronomical, with 30+ inches expected.

A Nor’easter is battering the East Coast from Virginia to Connecticut, unleashing widespread flood warnings and powerful wind gusts reaching up to 60 mph—especially along the Jersey Shore. Current projections: 🟪 3 gauges — Major Flood 🟥 17 gauges — Moderate Flood 🟧 40 gauges — Minor Flood

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#Erin has formed in the southeastern Atlantic and could potentially become the first hurricane of the season. While it’s still too early to determine if it poses a threat to the U.S. East Coast, conditions are becoming increasingly favorable for further intensification.

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Moderate Risk of Excessive Rainfall Issued! Affects areas along the I-95 corridor from Washington, D.C. to New York City. Rainfall rates may reach up to 3 inches per hour Localized totals could exceed 5-8 inches. Do NOT drive through floodwaters!

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Today is the "official" start to the Atlantic hurricane season. It is impossible to know what exactly will occur, but we can look to sea surface temperatures for clues. 2025 is definitely cooler than 2024 on June 1. Parts of the basin are warmer than recent analog years in 2008 / 2017. (1/n)

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Today we at Gallagher Re have released an initial assessment that estimates the May 14-20 stretch of US thunderstorms will drive $4-7 billion in insured losses. Uninsured damage is expected to drive the overall direct economic cost higher by at least another billion. (1/2)

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Moderate Risk (Level 4 of 5) issued for far North Texas, much of Central & Eastern Oklahoma, Southeast Kansas, and the Ozarks today. This continues the string of catastrophic convective storm systems that have battered parts of the U.S. in recent days. #SevereWeather

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Ideas for reform: stronger building codes, not developing risky areas, and a federal catastrophe backstop program designed for highly climate-vulnerable areas—covering those rare tail events with excessive losses once they exceed a prescribed limit, modeled on the Terrorism Risk Insurance Act (TRIA)

Steve Bowen@stevebowen.bsky.social · last yr.

NEW PUBLICATION ALERT "The growing void in the US homeowners insurance market: who should bear the rising cost of climate change? Co-authors: @monahemmati.bsky.social & Ian Gray (1/n) www.nature.com/articles/s44...

The #SPC has updated the Day 2 Convective Outlook, raising the risk to Level 5 out of 5—the highest possible threat level. The last time a Day 2 Outlook reached this level was in 2012! Be prepared to respond to this violent system tomorrow! #SCS

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A powerful weather system is sweeping across much of the U.S., bringing a range of extreme hazards. An extremely critical wildfire threat—the highest level—extends unusually far east into Texas and Oklahoma. Meanwhile, the central U.S. faces an increased risk of tornadoes and severe thunderstorms.

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Weather-related indemnity payout data for 2024 still coming in from the USDA's federally run crop insurance program. Total now tops $9.5B with drought accounting for >$4.1B alone. Several factors explain why loss payments have increased since 1990. Yes, more anomalous weather is one of them.

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