As we approach the busy part of hurricane season

The Atlantic hurricane season has its typical peak of the season in early September - the 10th.  While "first of the season" storms in May are not unheard of, which is before the season has actually started, those tend to be weaker storms, close to the US - things that develop around cold fronts coming offshore the continental US (CONUS).  We've had a couple of those this year, and one of them (Barry) came ashore out of the Pacific environment, crossed over Mexico and ended up being implicated in feeding the moisture that ended up in the horrific Texas floods earlier in July.  

But the peak of the season is approaching, and numbers of storms tend to start going up in August, as the development area moves from close to the US over to the tropical, low-latitude Atlantic.  "Low latitude" isn't a precise description and different graphics you'll find of it will show different latitudes.  Forecasters refer to this as the Main Development Region or MDR.  

Storms that start developing close to land in the US, including much of the Gulf, get good radar as well as good satellite observation.  There has been some hoopla about some satellites becoming unavailable to weather forecasters among the people that spend their lives looking for more "everyone is going to die" stories.  One of those is on Space.com today, "Hurricane forecasters are losing 3 key satellites ahead of peak storm season - a meteorologist explains why it matters."

The story is focused on the east end of the MDR, so close Africa.  It's too far for Hurricane Hunter planes to fly, so storms in the eastern MDR have been largely examined with satellite-based radars. 

On June 25, 2025, the Trump administration issued a service change notice announcing that the Defense Meteorological Satellite Program, DMSP, and the Navy’s Fleet Numerical Meteorology and Oceanography Center would terminate data collection, processing and distribution of all DMSP data no later than June 30. The data termination was postponed until July 31 following a request from the head of NASA’s Earth Science Division. 

These DMSP satellites are the best platform for examining storms out there.  

The three satellites orbit Earth 14 times per day with special sensor microwave imager/sounder instruments, or SSMIS. These let meteorologists look inside the clouds, similar to how an MRI in a hospital looks inside a human body. With these instruments, meteorologists can pinpoint the storm’s low-pressure center and identify signs of intensification.

Precisely locating the center of a hurricane improves forecasts of the storm’s future track. This lets meteorologists produce more accurate hurricane watches, warnings and evacuations.

It turns out that the best tool for locating the center of the storm is apparently the SSMIS sensor they talk about.  They report that hurricane track predictions have improved "by up to 75%" since 1990 and while they talk about improvement in predictions of intensification, they don't give a number like that.  

The problem, though, is that this is being blamed on budget cuts, not on the fact that planned replacements haven't been built or put up in orbit, yet.  

The DMSP satellites were launched between 1999 and 2009 and were designed to last for five years. They have now been operating for more than 15 years. The United States Space Force recently concluded that the DMSP satellites would reach the end of their lives between 2023 and 2026, so the data would likely have gone dark soon. 

There are other Satellites in orbit that can conceivably get useful data over the MDR: NOAA-20, NOAA-21 and Suomi NPP all have a microwave instrument known as the advanced technology microwave sounder.  More satellites are planned to use this ATMS, which can provide data similar to the currently used SSMIS, but at a lower resolution.  We've probably all seen low and high resolution images enough to imagine a blocky-chunky looking image of a hurricane from both kinds of resolution - we just don't know "how low is low" and just how degraded it is.  That last link ("at a lower resolution") is a substack article that provides a useful image which I changed from two images stacked vertically to being two side-by-side.

I puzzle over why the guys specifying the instruments (apparently) voluntarily went from the high resolution image on the left to the one on the right. 

The major question is still why are the current satellites in the 15th year of a five year mission?  It has been known since before the first one flew that they'd need to be replaced by now, so why didn't they build replacements immediately, so they could have launched in five years if need be?  Or wait a little and launch after 10 years. Based on the image quality between the old DMSP satellites and the newer one, they either think they don't need the better resolution or they simply can't decide what they need.