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Rapid Intensification Of Helene Expected Until Landfall

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London, GB
7:24 pm, Feb 13, 2025
weather icon 38°C | °F
L: 37° H: 40°
overcast clouds
Humidity 72 %
Pressure 1024 hPa
Wind 9 mph ENE
Wind Gust Wind Gust: 0 mph
Precipitation Precipitation: 0 inch
Dew Point Dew Point: 0°
Clouds Clouds: 100%
Rain Chance Rain Chance: 0%
Snow Snow: 0
Visibility Visibility: 6 mi
Air Quality Air Quality:
Sunrise Sunrise: 7:18 am
Sunset Sunset: 5:11 pm

Hurricane Helene is steadily intensifying this morning.  An eye is starting to form as pressure falls and winds begin to increase.  Intense convection is on the east side of the storm but starting to wrap around the low-level center.  The upper-level structure has matured and protecting Helene from any shear or dry air.  Helene will increase in forward speed through today and is expected to become a Category 3 major hurricane.

Helene will fall under the influence of a developing upper-level low-pressure system in the Mississippi River Valley and an upper-level ridge over the Southeastern United States, forcing Helene to quickly move to the north-northeast towards the Florida Panhandle by tomorrow night.  Between the upper-level low-pressure system and the upper-level ridge, the atmosphere will support an enhanced divergence at 250 MB, enhancing the rising motion of the warm-core low-pressure system.  This environment, combined with very warm waters in the eastern Gulf of Mexico, no wind shear, and very little dry air will increase the potential for rapid intensification of Helene into a major hurricane.  Aside from an eyewall replacement cycle or some mid-level dry air that is currently not seen in the guidance, there isn’t much to stop Helene from becoming a major hurricane with significant impacts on the Florida Panhandle.  In addition to the intensification, the speed of the storm will enhance sustained winds on the eastern side of the storm, possibly adding 10 to 20 mph winds on top of the observed sustained winds in the eyewall.

The interaction of the upper-level low-pressure system will create another unique dynamic to this storm threat for the rest of the Southeastern United States from the Gulf Coast to the Tennessee River Valley.  When an upper-level low-pressure system (cold core) interacts and absorbs a hurricane, the surface low-pressure system rapidly transitions into an extratropical storm with the rain shield expanding and the wind field expanding while core winds subside.  So, instead of 115 mph wind, the storm features 50 mph sustained wind but over a 40 mile radius rather than a 10 mile radius.  Any way you slice it, this storm will have significant and lasting impacts on the Southeast.

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