Tropical trio: Ingrid forms, Gabrielle and Humberto weaken

September 13, 2013

On the fifth anniversary of Hurricane Ike’s landfall on Texas, Tropical Storm Ingrid forms in the Gulf of Mexico.  Further east, Gabrielle and Humberto were both recently downgraded.

Ingrid Drenching Mexico

Enhanced infrared satellite image of Ingrid in the Bay of Campeche. The strongest thunderstorms and heavy rain show up in the blues, greens, reds, and yellows. (CIRA/RAMMB)
Enhanced infrared satellite image of Ingrid in the Bay of Campeche. The strongest thunderstorms and heavy rain show up in the blues, greens, reds and yellows. (CIRA/RAMMB)

Tropical Depression 10 formed yesterday afternoon in the Bay of Campeche, and as I wrote in yesterday’s update, a combination of satellite measurements, aircraft reconnaissance data, and radar imagery has helped to continuously pin down the intensity and position.

At 11 a.m. EDT today, TD #10 was upgraded to Tropical Storm Ingrid, the ninth named storm of the season.  The center is located just 60 miles off the Mexican coastline near Veracruz, but is forecast to stall before turning to the north.  You can track the center via the Alvarado radar.  Landfall is expected early Monday near Tampico, according to the latest National Hurricane Center forecast shown below.

Ingrid's forecast track, along with tropical storm warnings (blue) and tropical storm watches (yellow). (NOAA)
Ingrid’s forecast track, along with tropical storm warnings (blue) and tropical storm watches (yellow). (NOAA)

The biggest danger from Ingrid will be the rain and resulting flash floods and mudslides.  10-15″ of rain is forecast over much of eastern Mexico in the coming days, with up to two FEET in local areas.

Humberto Weakens… For Now

As expected, Humberto has tracked north into higher shear and drier air, and was downgraded to a tropical storm at 11 a.m. EDT today.  The strongest thunderstorms associated with it are displaced well to the east now, and in the image below, another large plume of dry dusty air can be seen streaming off of the African continent.


Visible satellite image of Tropical Storm Humberto… the African coast is on the far right, the Cape Verde islands are in the bottom center. (NRLMRY)

By early next week, environmental conditions are expected to become more favorable for development, and many models show a re-intensification back to a borderline hurricane. Humberto will remain very far away from land though. The plot below shows several parameters from a variety of models. On the left is intensity and track, then on the right is wind shear, sea surface temperature, and mid-level humidity.  You can see that conditions are approaching the most hostile (high wind shear, cool sea surface temperatures, low humidity), but should recover in 3-4 days allowing the storm to strengthen again.


So, we will likely be watching Humberto for at least another week in the central Atlantic.

Gabrielle’s Last Breath

The first advisory written for Gabrielle (it was Tropical Depression 7 then) was nine days ago, then it dissipated for a few days before coming back to life.  Today it has once again weakened to a depression for the last time.  The vertical wind shear is up to about 35 mph, the ocean temperature under the storm is decreasing, and it’s beginning to take on characteristics of an extratropical cyclone as it merges with a frontal system.  It, or its remnants, is still expected to hit Nova Scotia later tonight and bring heavy rain and gusty winds.


Visible satellite image of Tropical Depression Gabrielle at 10 a.m. EDT. (NASA)

With this little bit of surge in activity, the ACE (Accumulated Cyclone Energy) is gaining some ground on climatology.  Prior to this flurry of storms, we were at 18% of normal for the date, but now it’s at 31% of normal for this date.

* Brian McNoldy is a senior researcher at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science.

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Dan Stillman · September 13, 2013