Tropical Storm Danny and a look at the Northeast

Good afternoon everyone!

Well up to now its been rather quiet in the deep tropics thanks to our El Nino , but as you all know that has changed.

Tropical storm danny was named earlier today  , here are latest coordinates and data:

As of 18:00 UTC Aug 18, 2015:

Location: 10.8°N 37.0°W
Maximum Winds: 35 kt Gusts: N/A
Minimum Central Pressure: 1008 mb
Environmental Pressure: 1013 mb
Radius of Circulation: 150 NM
Radius of Maximum Wind: 40 NM
Eye Diameter: N/A

Tropical storm danny came out as a wave off of cape verde embedded in a monsoon trough, which is acting like a security blanket from the very dry air to its north due to the trade winds.

The moisture loaded environment to danny’s south is helping to keep danny protected at least for now from the dust to the north.

The latest data observations show cloud tops at around -70C which is pretty impressive , and convection wrapped around the low level center of circulation.

This storm right now is pretty healthy , the outflow is nicely defined to its north and south of circulation. The inflow has plenty of moisture being drawn in

thanks to the monsoon trough with no dry air distraction , and the upper level air pattern is a light easterly wind which these storms like. The wind shear in its current environment is actually non existent and a major factor in its predicted rapid intensification.

Why is this important? , tropical cyclones development requires relatively low values of vertical wind shear so that their warm core can remain above their surface circulation center which promotes cyclone

strengthening. Vertical wind shear tears up the mechanics of the heat engine ( warm tropical ocean and colder upper air atmosphere) causing it to break down.

Strong shear in tropical cyclones weaken as the upper circulation is blown away from the low level center. When vertical shear is weak , the storms that are part of the cyclone grow vertically and the latent heat

is released into the air directly above the storm aiding in development.

Here is the latest plot analysis from the NOAA


Some models have danny reaching hurricane status just before the lesser antilles and lee ward islands ,however, once it enters the eastern caribbean it will encounter a strong wind shear zone.

A ridge to its north is predicted to grow in time as a twin of troughs in the atlantic move out which will pin danny to the south and not let it move north. Plenty of time to watch this evolve , updates as needed will be provided.





The shower and thunderstorm producer for the northern mid atlantic and northeast for the rest of the work week and into the weekend is shown above.

A trough will move northeastward from the great lakes through ontario into western quebec which will force a cold front into the ohio river valley.

The threat for showers and thunderstorms tomorrow on through friday as the cold front pivots towards the east coast. I am keeping the severe threat limited  to the interior sections of PA , NY and new england ( although threat is weak to marginal )

as winds from the surface to the mid levels shift to a SE direction which will help to bring in a more stable atmosphere albeit moisture loaded.


The main threat from these showers and thunderstorms will be very heavy downpours ,which will lead to flash flooding in certain locations.

The threat for showers and storms continues into weekend with a continued on shore flow and frontal boundary meandering around the northern mid atlantic.




Meteorologist Steve Garry




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