WeatherTiger

Very cool long water vapor loop of #Humberto and #Imelda between September 28th and October 1st from College of DuPage, btw.

Whirlwind Tour: Hurricane Watch Weekly Column for October 1st Wrapping up Humbertimelda mania and looking at historical October hurricane risks.

Wrapping up Humbertimelda mania, looking at what the home stretch of hurricane season is historically packing, and checking how the forecast for the next few weeks lines up with climatology.

All that plus spooky, scary skeletons in this week’s WeatherTiger hurricane column:

WeatherTiger's Potential Tropical Cyclone Nine Forecast for September 27th PTC 9 is expected to approach the Carolinas in around 3 days, with an uncertain forecast thereafter.

Potential Tropical Cyclone 9 will strengthen to a tropical storm and move north-northwest through the Bahamas this weekend.

Our latest on an uncertain forecast for potential coastal rain and wind impacts for Florida north to the Carolinas:

TS #Humberto and #Invest94L continue to be features to watch closely. The bigger threat, Invest #94L, should follow a steering channel east of #Florida this weekend. #Carolinas have a higher chance of a direct landfall early next week.

Thursday update here: weathertiger.substack.com/p/dont-call-...

Folie à Deux: Hurricane Watch Weekly Column for September 24th Making sense of the chance that two tropical systems interact east of Florida early next week, and what that means for possible U.S. weather impacts.

One year after Helene/Milton Hurricane Hell Fortnight '24, milder double trouble is here as #Invest93L & #Invest94L may track close enough to interact this week. Odds tilt away from major U.S. impacts, but worth watching from #Florida to the Carolinas.

The latest on a possible Hurricane Heck Week:

Never Ending Math Equation: Hurricane Watch Weekly Column for September 17th TS Gabrielle forms but is no threat, as we look at how AI is making an impact on hurricane forecasts.

For the 1st time in 84 years, correction, 3 weeks, there is a storm in the Atlantic: Gabrielle, a strung-out mess that poses no risk other than to Bermuda.

With a quiet Atlantic continuing, I'm taking a deep dive into AI weather/hurricane prediction this week. Am I about to be replaced by Skynet?

Stolen Thunder: Hurricane Watch Weekly Column for September 10th Hurricane season has fallen. Can it get up? We develop a new model to address that question.

Thanks for reading and here's hoping that the luck of the 1st half of hurricane season can last through the 2nd half. After a record 10 major hurricanes in 9 yrs we need a break on the Gulf Coast.

Check out my full analysis of late-season landfall risks here:

So, the war between favorable ocean & hostile atmospheric conditions may persist in the final third of hurricane season and U.S. landfall risks.

WeatherTiger's model of post-9/20 Gulf/W. Carib tropical activity is a bit above normal but not nearly as busy as 2020/24 late seasons.

The 2nd key predictor of post-9/20 Gulf/W. Carib activity is September ridging over the SE United States. More Sept. ridging is correlated with more hurricane activity.

Sept. 2025 has been the exact opposite of this pattern so far: persistent deep troughing over the eastern U.S.

Only Gulf & W. Caribbean (west of 75W) activity post-9/20 translates to more late season U.S. landfalls.

SSTs are 1 key predictor of late season Gulf/Carib storms. More activity is linked to warm Caribbean/C. Atlantic, colder Pacific/Nina conditions. Sept. 2025 resembles that.

Conditions in the east Atlantic may become more conducive for waves to develop in the next week.

But that may not translate to U.S. landfall risks. After 9/20, more hurricane activity east of the Lesser Antilles is actually linked to slightly fewer late-season U.S. landfalls.

In short, nearly the entire Atlantic Basin has seen less convection (tstorms) than normal over the last month because of persistent sinking air aloft and mid-level dry air incursions.

Convection is the building block of tropical cyclones, so no convection, no hurricanes. 2/7

If you follow the Tropical Atlantic, you might be confused like our friend Vincent Vega here by the lack of any named storms since August 28th, a timeframe that is the climatological peak of #hurricane season.

So what's going on, and will it continue? Thread: (1/7)

Stolen Thunder: Hurricane Watch Weekly Column for September 10th Hurricane season has fallen. Can it get up? We develop a new model to address that question.

If like Travolta here, you're confused by the quiet peak week of hurricane season, we’ve got you covered. Today’s column breaks down the reasons for this lull and rolls out fresh predictions from our model of late-season U.S. landfall risks.

Bottom line, stay light on your feet like Johnny.

[Annual post]

Convection crippled by the dry air that keeps on blowin'
Subsidence imposin'
And we

Keep bleeding, keep, keep bleeding ACE
And we keep bleeding, keep, keep bleeding ACE
Keep bleeding, keep, keep bleeding ACE

Shear cuts waves open

With Invest 91L succumbing to dry air and subsidence and no longer a threat to develop, here's a look at this morning's NHC Tropical Weather Outlook:

Halftime Show: Hurricane Watch Weekly Column for September 3rd Monitoring a potential hurricane threat to the Antilles as we gear up for what will likely be a busy second half of hurricane season.

It's been a quiet, hopeful first half of #hurricane season, but there are possible signs of trouble brewing for the second half.

This week’s column discusses a tropical wave in the eastern Atlantic likely to become the next tropical storm, as well as updated U.S. seasonal landfall probabilities.

ACE/Off: Hurricane Watch Weekly Column for August 27th An oddly quiet week in the Tropics is a chance to look back at Katrina and ahead to September hurricane history.

It's always a happy Labor Day weekend without a hurricane. Even high rain chances for Florida, beats the historical alternative.

An oddly quiet week in the Tropics is a chance to look back at Katrina and ahead to September. Cherish the reprieve, because climatology tells us it won’t last forever.

Atlantic Tropical development is unlikely in the last week of August.

That's a little unusual: over the last 75 years, at least one tropical storm has formed ~60% of the time. At least one hurricane developed in ~40% of seasons.

Nice easy week. Cherish it while it lasts.

The scope of 2-2.5' surge today with #Erin is very impressive, spanning all the way from North Carolina to New Jersey despite a track 300+ miles offshore.

This evening's high tide will be the highest water for the mid-Atlantic, and moderate flood stage is possible in some locations. Be safe!

Spiraling: Hurricane Watch Weekly Column for August 20th Hurricane Erin goes full 🌀 as it sends potent waves and some surge to the U.S. East Coast, while thankfully remaining offshore.

Reels and ‘Toks to the contrary, Hurricane Erin did not snap the U.S. East Coast’s 21-year streak without a Cat 3+ landfall. And good thing, because it's a monster.

Latest on Erin’s wave, surge, rip current, and wind impacts, plus why it's the last threat for a while in this week’s tropical column.

With Category 4 #HurricaneErin ripping ~20 ACE units so far (and 15-20 ACE to go), the 2025 #HurricaneSeason has rapidly vaulted out of the climatological basement— moving up from <30th percentile to date last week to nearly 80th percentile today.

More percentile gains from #Erin to come.

Peak Hype: Hurricane Watch Weekly Column for August 13th Erin will become 2025's first Atlantic hurricane as peak season kicks off, but despite the chatter it poses little threat to the continental U.S.

Historically, storms forming east of the Lesser Antilles have a ~20% chance to make landfall in the U.S.

TS Erin is not likely to beat those odds, despite what you may have seen from drama mongers with names like Gulf Coast Hurricane/Monster Jam ALERT HQ this week.

Here's the scientific real deal:

Despite chatter, odds are stacked against Tropical Storm Erin having U.S. impacts- just around 5% of historical storms near Erin's location later struck the U.S. coast.

Worth watching as #Erin will likely become the first major hurricane of 2025, but certainly no cause for alarm stateside.

Erin on the Side of Caution: The Hurricane Watch for August 11th Tropical Storm Erin has developed and is expected to strengthen, but is not likely to threaten the U.S. coastline.

Tropical Storm Erin has developed, and the NHC is projecting it to reach hurricane strength by late Wednesday and become the first major hurricane of the year on Saturday.

Indications are that Erin will be a strong hurricane that passes north of the Lesser Antilles and east of the continental U.S.

August and Everything After: Hurricane Watch Weekly Column for July 30th A quiet Atlantic offers a chance to look ahead to August hurricane history, when U.S. hurricane risks historically accelerate.

Thankfully, August 2025 will begin with minimal tropical activity in the first third of the month.

That frees me up this week for another entry in my guided tour of hurricane season, this time looking at August: when the heat index and prospect of serious tropical threats are gonna make you sweat.

Of course, 94% of historical ACE has occurred after this date, and the correlation between June/July ACE and August-November ACE is minimal, so that doesn't necessarily mean anything. Personally, I would be thrilled if the hurricane season remained sluggish throughout 2025, as would most in Florida.

Named storms aren't a great way of assessing seasonal activity. Accumulated Cyclone Energy, accounting for both intensity and longevity of storms, is better.

Currently, 2025 is a 28th percentile season to date in terms of ACE, which I would call somewhat below average or even "a slow start."

WeatherTiger's Hurricane Season Outlook for July 2025: Part 1 Different methods suggest divergent possible outcomes for the season ahead.

Hurricane Season 2025 is off to a slow start, but there’s a lot of season left to go— nearly 95% in ACE terms.

In today's updated Seasonal Outlook (part 1), WeatherTiger’s real-time algorithm is making sense of conflicting data, projecting a most likely outcome of around 135 ACE units. More here: