June 2025

June 24, 2025

Sad sack of clouds becomes Atlantic's first named storm of 2025

A center of low pressure over the north-central Atlantic Ocean earned the distinction of becoming the basin's first named tropical system of the year on Tuesday.

After several days of playing "will it, won't it," the system displayed enough thunderstorm activity near the center of the storm to qualify as Tropical Storm Andrea.

The National Hurricane Center wrote in their forecast discussion: "Even though deep convection is now decreasing, due to the persistent convection overnight and pulsing convection over the past 36 hours, the system has met the criteria of being classified as a tropical storm, albeit a marginal one, making Tropical Storm Andrea the first Atlantic storm of the year."

That's meteorologist-ese for "it's a sad sack of clouds." Andrea will remain out to sea and should fall apart by Wednesday morning.

Climatologically speaking, the Atlantic's first named storm usually forms around June 20th, so we're only a few days behind on that front. The heart of the season remains a long way off—activity usually ramps up in August before reaching its peak during the second week of September.

Seasonal outlooks published by both NOAA and Colorado State University call for an above-average season across the Atlantic in the weeks and months ahead. These forecasts are based on warmer-than-usual ocean waters, an uptick in monsoon activity over western Africa, and a lack of El Niño conditions in the Pacific Ocean.

Make sure you're prepared for hurricane season well before a storm forms—whether you're on the coast or hundreds of miles inland.

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June 17, 2025

Upcoming heat wave isn't "just summer." Heat is a prolific killer.

Dennis Mersereau 6/17/2025 04:32:00 PM extreme heat heat wave Leave a Reply

The first major heat wave of the season is on the way for a large swath of the eastern United States, with a prolonged stretch of daytime high temperatures in the 90s with heat indices in the 100s likely.

Every time we get a big heat wave, social media lights up with that classic line: "It's called summer."

Always typed with the sneering smugness of a seventh grader, that three-word phrase is a catch-all to wave away any concern about an upcoming spell of dangerously hot temperatures.

Extreme heat is deadly

Heat is deadly. It's always been deadly. Lots and lots of people died "back in the day" during heat waves. Lots and lots of people still die during heat waves. You just don't hear as much about it because their deaths weren't caused by dramatic winds or rushing waters.

Extreme heat caused nearly half of all weather-related fatalities between 2014 and 2024—often surpassing the tolls exacted by tornado outbreaks, major hurricane landfalls, and devastating flash flood events.

Why extreme heat kills

Heat waves exact large human cost because of humidity, hot nights, and longevity.

Humidity: Sweat cools off our bodies through evaporative cooling—water absorbs heat when it evaporates from liquid to gas. This process pulls heat from our skin to cool our body temperature on a hot day. Excess moisture in the air interferes with this process by preventing sweat from evaporating efficiently, even when you have fans running. The heat index accounts for the combined stress that heat and humidity place on your body.

Hot nights: People who live without air conditioning rely on cooler nighttime temperatures to provide their bodies relief from a hot day. Hot days and elevated nighttime temperatures—alongside smothering humidity—robs these folks of the ability to cool off at night.

Longevity: The compounding effects of stifling hot days and steamy nights takes a significant toll on vulnerable people. Those without access to air conditioning, folks working outdoors, and chronically ill individuals are highly susceptible to heat-related illnesses such as heat exhaustion and heat stroke.

Upcoming heat wave

Image: Tropical Tidbits

A classic summertime heat event will build east of the Rockies heading into this weekend.

We'll see a large and strong upper-level ridge develop and move toward the Ohio Valley on Saturday, lingering over the eastern half of the country well into next week.

Air sinks beneath ridges, warming up and drying out as it descends toward the ground. Very strong and stubborn ridges of high pressure like this can trigger a feedback cycle that compounds the effects of heat and humidity for days on end. Meteorologists sometimes like to call this a "heat dome."

As a result, extreme heat is likely to build over a vast swath of the country beginning this weekend. The above graphic shows the National Weather Service's experimental "HeatRisk" product, which conveys the potential danger of predicted heat. Communities in the "major impacts" and "extreme impacts" zones could see conditions that may threaten the health of even physically fit individuals.

Widespread heat alerts are likely.

It only takes heat index values or air temperatures up around 100°F to trigger heat advisories across much of the northern United States. Remember, the impacts of heat are relative. Folks in the south are more acclimated to muggy heat than folks up north, so lower temperatures can have a higher impact in, say, Toledo than Mobile.

Get ready for a long and dangerously hot stretch of weather heading into next week. Heat is no joke—and don't let the naysayers convince you otherwise.

June 9, 2025

Huge hail, ripping winds—PDS severe weather watches are relatively rare

Dennis Mersereau 6/09/2025 04:43:00 PM particularly dangerous situation Leave a Reply

Sunday was quite the day on the southern Plains as forecasters tracked a severe weather outbreak capable of producing giant hailstones and destructive wind gusts.

The Storm Prediction Center (SPC) issued two relatively rare particularly dangerous situation (PDS) severe thunderstorm watches for a large swath of the region through Sunday evening.

How rare was this setup?

Extreme instability fueled an unusually robust risk for severe thunderstorms across northern Texas and southern Oklahoma on Sunday. As we see with so many severe weather outbreaks, it was a one-two punch: first supercells with a threat for tornadoes and huge hail, then a squall line capable of producing widespread damaging winds.

Given the setup, the SPC pulled no punches in their severe thunderstorm watches. Forecasters advised that the strongest storms could produce hail up to 5 inches in diameter—larger than a DVD—as well as wind gusts in excess of 100 mph.

Large hail and damaging winds were common throughout the northern half of Texas as storms progressed through the afternoon and past sunset. While many communities made it through the day unscathed, not everyone was so lucky.

A nasty supercell southeast of Amarillo, Texas, produced softball size hail near Claude and a 90 mph wind gust near Lakeview. A little farther down the road, a weather station near the town of Goree measured a 100 mph wind gust.

The SPC adds the phrase "particularly dangerous situation" to severe thunderstorm or tornado watches during setups that could pack unusual intensity across the region.

A PDS tornado watch is issued when forecasters are confident in an outbreak of strong, long-lived tornadoes. A PDS severe thunderstorm watch is reserved for the potential for widespread destructive hail or winds—much as we saw on Sunday.

Including the two issued this weekend, we've only seen 168 PDS watches since the Iowa Environmental Mesonet began keeping track in 2006. This equates to about 5 per year. 142 (85%) of those were tornado watches, while the remaining 26 (15%) were severe thunderstorm watches.

June 3, 2025

Low chance of Atlantic's first named storm this week

Dennis Mersereau 6/03/2025 04:23:00 PM atlantic tropics Leave a Reply

Welcome back to that time of year—a tiresome six-month marathon of watching centers of low pressure and disturbances for signs of tropical development.

We've got our first candidate on the board just after the official kickoff of this year's Atlantic hurricane season.

Low Odds of Development This Week

Forecasters with the National Hurricane Center are monitoring a developing low-pressure system off the coast of the southeastern states for potential development. The area had a 10 percent chance of development on Tuesday afternoon—not a great opportunity, but not impossible either.

Regardless of development, plenty of gloomy and showery weather is on tap for coastal communities heading into this weekend. The National Weather Service is calling for several inches of additional rainfall from southern Florida through eastern North Carolina.

Potentially Busy Season Ahead

Conditions appear favorable for a potentially active Atlantic hurricane season this year. Both NOAA and Colorado State University expect an above-average Atlantic hurricane season, exceeding the normal count of 14 named storms, 7 hurricanes, and 3 major hurricanes.

If these forecasts come to pass, this would be our tenth (!!!) above-average season in a row—a relentless slog that's seen ten scale-topping Category 5 hurricanes, plus a barrage of flood disasters too numerous to remember offhand.

This year's list of storm names begins with Andrea and continues through Wendy, skipping the letters Q, U, X, Y, and Z for lack of replacements should one warrant retirement. This list of names was last used in 2019, and it features a new addition in Dexter after the retirement of Dorian.

In the unlikely—but not unprecedented—event we run through all 21 storm names, the 22nd named storm of the year would be drawn from a list of supplemental names developed by the World Meteorological Organization after the historic 2020 hurricane season tore into the Greek alphabet.