June 4, 2025 Tropical Update Wednesday

Non-tropical low to develop off Carolinas Friday

We are now in the 2025 Atlantic Hurricane Season [Day 4]. My expectation for this year is 14 named storms, 7 hurricanes, and 3 majors.

Also, thank you to [new] subscribers continuing into this Hurricane Season. My goal is to keep you informed about ongoing extreme weather events inside and outside of the tropics, but also a week (hopefully) heads up on what’s coming. I’ll be using a variety of weather modeling output, some of it may be unfamiliar, but it’s state-of-the-art and industry leading standard.

Wednesday’s Tropical Weather Headlines

1. Atlantic tropical update: A 10% chance of tropical storm development expected in next 2-3 days —> A frontal boundary with a non-tropical low will form off the Southeast / Carolinas coast and could [briefly] acquire tropical characteristics.

2. Gulf and Caribbean — otherwise no activity expected through 7-days.

3. Eastern Pacific tropical update: NHC increased to 80% chance of next system in 7-days — Barbara, with another system into next week.

4. A new Saharan Dust / Air Layer has blasted off the African coast.

5. Climatology: the lack of a hurricane strength system in the Northern Hemisphere through June 4th — today — means a record for inactivity, at least since 1973. The Western Pacific usually sees several typhoons by now in early June, but nothing brewing for a while. Also, Alvin in the Eastern Pacific failed to reach hurricane strength.

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ECMWF 00Z | Integrated Vapor Transport | Next 10-days

The ECMWF HRES (control) IVT model simulation for the next 10-days does not show anything spinning w/ a likely tropical designation across the Atlantic — unless/except the little swirl off the Southeast coast qualifies.

Development of “Barbara” in the Eastern Pacific now up to 80% and seems likely by later this weekend. However, the models — outside of GFS — indicate a mid-range tropical storm (50-knots) as the outcome (like Alvin).

Another system south of Mexico could then develop in 8-10 days with some ECMWF ensembles show it crossing into the southern Gulf of Mexico (America).

The feature off the Southeast U.S. coast is related to the tail end of a decaying/stationary cold front. A circulation will spin-up over the very warm waters of the Gulf Stream and MAY burst convection long enough to get a 6-12 hour tropical depression or tropical storm (Andrea).

—> Many June storms last less than a day, but count just the same!

We use the ECMWF for medium-range prediction because the GFS can’t be trusted due to false-alarm bias, and unrealistic intensification.

Tropical Atlantic | Precipitation and MSLP Next 10-days