Will the southeast coast Take a hit?

 

During yesterday's  drought condition post. I said the Madden Julian Oscillation (MJO) is going to be favorable. This could lead to more tropical activity as we move further through the second half of the season. I wanted to go into little more detail on what it is and why it's important.

Basically The MJO is a wave that moves west to east across the equatorial tropics.

The MJO has a strong impact on tropical activity in many areas across the tropical oceans. It's a big  factor in precipitation patterns, variations in sea surface temperature, low level winds, vertical wind shear, variations in atmospheric temperature and humidity levels. All major factors when it comes to tropical cyclone development.

A very basic overview Of the MJO.

There are 8 phases in the MJO.  The MJO originates in the Indian ocean then it travels east across the pacific. When the MJO gets into the far eastern pacific heading towards the Gulf of America, It Disrupts the pattern  and causes lower height leading to general lower pressures to develop. As the wave propagates eastward across the Atlantic these conditions continue to follow it. This ends up causing precipitation resulting in storms. If  there's enough energy these storms can develop a spin and we can see a tropical cyclone develop. Generally when the MJO is in phases 1,2 and sometimes into 3. It creates conditions that are favorable for tropical cyclone development in the Atlantic basin.

Humberto:

He looks very healthy on satellite. But he is still dealing with a little bit of wind shear, But that is going to continue to  lessen

Humberto underwent rapid intensification and now has maximum sustained winds Of 90 mph, with a minimum central pressure of 979MB. Because he sees 94L he is slowing down and currently is moving northwest at around 5 mph .

Image credit Tomer Burg

Humberto has been dealing with wind shear of 25-30 knot, But that is relaxing. So, Humberto will likely become a major hurricane over the weekend.  If that occurs, all three hurricanes that have formed so far this season, will also have become major Hurricanes. 

Because of I94L the western extent of Humberto's track is limited. The center of circulation between the two systems will anchor him off the coast and force him to pivot and the move north and east away from the East Coast. Right now Humberto looks to pass west of Bermuda. It is possible he could pass close enough to bring tropical storm conditions to the island.

Invest 94L:

The National Hurricane Center is giving this 2 day development odds of 90%

94L has been dealing with the mountainous terrain of Haiti and eastern Cuba. Therefore it looks rather messy at the moment.  But today it will be pulling away from all that and head towards the Bahamas. On the satellite 94L's convection is looking much better than it was yesterday

Image credit Tomer Burg

The sea surface temperatures (SST) In the northeast Caribbean and around the Bahamas are 85-86° Fahrenheit. Wind Sheer has also been a moderate 25-30 knot.

Image credit tropical tidbits.

Image credit university of Wisconsin.

Over the weekend the wind shear is going to relax and the upper level pattern will begin to become favorable for the development of I94L. Given the conditions 94L will likely become Tropical Storm Imelda over the weekend.

We have low pressure in the Tennessee valley,  along with that trough near the Southeast. We also have that high pressure out over the Atlantic. All of these create a flow that would normally allow I-94L to approach from the south and east and make a landfall on the Carolinas. Humberto Is also going to help steer I94L towards the coast. Due to it helping to pump the ridge to the east of I94L. This will act as a block keeping or at least delaying 94L from trying to slip out to sea.

Image credit Tomer Burg

The overall setup keeps I94L  away from the coast of Florida as this churns north and west. If 94L approaches the Coast, wind shear will be increasing closer to the coast But it will be out of the south and west.  The water is going to be warm and the wind shear coming from this direction could allow a storm approaching from the south and east a chance for even more intensification. So it's very possible the Southeast coast could have an approaching hurricane. Has 94L gets closer to the coast it will be dealing with dry air. This should keep it from rapidly intensifying over the warm waters of the Gulf stream. So the most likely scenario would have a strong tropical storm or a category 1 hurricane making landfall Monday into Tuesday.

Normally a setup like this with the overall steering current would be a slam dunk for this to plow into the Carolinas. But that's not the case this time. The fly in the ointment is going to be Humberto. Depending on his strength and location It's possible he could influence the circulation pattern enough to slow I-94L and turn it to the north and northeast and out to sea. 

Right now Based on the setup I see I think the odds of a landfall on the Carolinas is 75%-80% with the odds of this staying just off the Coast and going out to sea 20%-25%.

Any landfall would likely be between the Georgia/South Carolina border and the Outer Banks of North Carolina.

As I said in the earlier weather update. The Northeast and northern Middle Atlantic are going to be protected by the northern stream. Regardless of a landfall, the flow is going to limit the northern extent of 94L's track forcing it to to recurve out to sea, or forcing it to sit over the interior southeast where it would weaken and dissipate.

Regardless of this becoming a hurricane or not, This scenario is not good news for the Southeast. If I-94L makes a landfall 6-14  inches of rain is a likely bet. This will be especially tough for the mountainous terrain of the western Carolinas. The worst case scenario I94L ends up sitting and spinning for awhile. Right now rainfall amounts don't look to be bad as Irene was. So that's at least a sliver of good news.

Gabrielle brought significant wind and wave action to the Azores. She will continue to move towards Portugal. This is likely my last post dealing with Gabrielle