Severe Weather July 18 2013

For the past several days we have had a Bermuda High Pressure in control and the result has been a very hot and humid air mass across the vast majority of the country. Temperatures have been in the 90s and real feel temperatures have been even higher. With an air mass in place like this to get severe weather you need  a cold front with a temperature difference behind that cold front and when you have these two air masses colliding one with another it brings about the chance of severe weather.. We have a cold front that will be dropping south and east from the Canadian Border and this front will serve as the necessary trigger for severe weather to occur. We expect today that all modes of severe will be possible ...

As we noted the temperatures are hot across the vast majority of the region with temperatures in the 80s and the 90s and the real feel temperatures in some locales will be between 100-105 degrees.

Factor in dew points in the 60s and 70s and once again you have the recipe for some very hot weather.
Moving on to the severe parameters that will be in place....

Convective Available Potential Energy or CAPE is essentially fuel that gets thrown on the fire. This will range from 1000 to as much as 4000

Lift in the atmosphere or the Lift Index will be from about negative 2 to negative 8..

Wind Shear with this system coming down across the lakes is essentially from 35 knots to 60 knots. 

Energy Helicity Index is relatively high across Northern Minnesota and across Northern Wisconsin and Upper Michigan . In tandem with this the HELICITY is also on the higher side...

So these areas mentioned above are the regions that we think have the potential for Tornadoe's. Elsewhere we think the main threats will be heavy rain, damaging winds and the potential for Hail...

So this is the zone we have highlighted...

Keep in mind that over the next couple days that this front will be moving south and east and this means that the severe potential will also move south and east .

For those that are in the areas that are extremely hot ... we want to stress that you should drink plenty of liquids and if at all possible stay indoors and in the Air Conditioning. If you must venture outdoors take Water with you and wear light colored and loose fitting clothing...

Invest 96 L ..The Remnants of Chantal

There is some confusion out in the world of weather on the internet with Invest 96 L. Invest 96 L is simply the remnants of Chantal ..so if it were to regenerate into a tropical storm it would acquire the name of Chantel.
National Hurricane Center has this at a 30% chance of re developing..

Some graphical images of the remnants of Chantal ..

Right now we do not view conditions as all that favorable for redevelopment...

Wind shear which is a deterrent to tropical cyclones strengthening is at about 20 knots..

You can also see this looking at the wind shear tendency image and see that there is shear all around this system..

Some things are in favor however of possible development and that would be the convergence and divergence that is presently over the system..

And another factor in favor is that the vorticity is not elongated ..

However you can see that the vorticities are not vertically aligned or stacked at the 850 level ,700 level or 500 level..

These centers would have to become vertically aligned or stacked if we want to see redevelopment out of this system. We think with the shear being at about 20 knots that any development of this system will be slow to occur...

The tracks as of 00z for this system become kind of interesting:

They take the system up along the east coast of Florida (majority) and then inland and this would be because of interaction with the upper level low in the southeast.
Intensity forecasts , all but one model take this back to tropical storm strength...

This would be between 24 and 48 hours out in time. However...like we mentioned above we would like to see the wind shear ease up some in order for redevelopment to take place. 

The steering currents that are in place indeed would support a movement almost due NNW as it moves around the Western Atlantic Ridge.

So we do not think that Chantal is a factor that we should just ignore as we do think that she could regenerate back into a Tropical Depression or a Tropical storm but we just think that it may take a little longer until the wind shear lets up a  little bit. Those in Florida should be keeping an eye on this system. Irregardless of development or not she should provide some heavy rain across Florida...

We will continue to monitor the situation and see where we are with this by this time later tonight. 

Severe Weather Potential July 10th 2013

A cold front is going to be making its way to the south and east and moving thru and into a very warm and humid air mass. It will be this front that will be the focal point for severe weather potential and in the Southwest a trough will be moving towards the east and this will serve as a potential for severe weather in that region as well.

Dew points are going to be in the 60s and 70s making it feel very warm and humid across the region highlighted for severe weather..

Air temperatures are going to be in the 80s and 90s and so when you factor in the high dew points you can pretty much bank on it being very warm , hot and humid.

Convective Available Potential energy is going to be running anywhere between 1000 and about 4000. So we do have some fuel in place ...

There will be plenty of lift in the atmosphere from 0 which is very meager to about negative 9 which is ample enough for severe weather ..

Shear is going to be highest across the northern most extent of the severe zone where it will be 30 knots plus...elsewhere the shear will be very marginal. 

EHI will be at 1 or above across a large area which means there will be a potential for supercells to take place and there are some isolated pockets where the EHI is higher and it is these locations where we think the possibility of a tornado could exist. If you are not in those locations then we are talking about winds and hail and heavy rain with any storms being the main threats. The outlook is below..

Tropical Storm Chantal Update

The latest information on Tropical Storm Chantal is that the wind speeds are up to 50 MPH. We mentioned in the update last night that conditions were favorable for slow intensification. Conditions are still favorable for some more intensification to take place. The one thing that continues to work against Chantal however is her forward speed which is 26 MPH. 

The above are the latest rainbow IR satellite presentation. Chantal is moving off to the west northwest and should continue to do so until she begins to feel a weakness that will develop in the ridge that she is under..

On the present path that she is moving Chantal should go over and across Hispanola. The island of Hispanola has become famous for shredding apart tropical systems ..especially if they are not to strong and organized. So Hispanola could potentially cause the system to become an open wave.. However...another possibility is that the speed that the storm is moving may also be able to prevent to much damage from being done which would allow the storm to stay intact and then once again be able to re intensify. 
Guidance tonight is starting to show a west ward bend towards Florida..

The GGEM shows this actually making landfall a little bit North of Florida and shows a slow down in speed once across Hispanola.. Here is the GGEM at 132 hours out..

00z UKMET shows a similar situation but weaker...

00z GFS takes Chantal into Florida.. and is slower being that the image below is 150 hours out..

Lets take a look at current conditions around Chantal...

Shear right now is not really an issue being that it is presently in a area of about 5-10 knots but notice off to the west northwest the shear does increase. And you can see this shear increase on the shear tendency map as well

Vorticity seems a little bit more broad this morning compared to yesterday at this time frame.

The greatest convergence lays off to the southwest of the system...

However, divergence across the system is decent at the present time. 

In summary we think that this has room to intensify some before it encounters Hispanola and depending on how fast CHANTAL moves across Hispanola and how strong she is will determine whether or not she can survive the journey across the island.
Presently we think that anywhere from Florida to the Carolinas has to keep an eye on this system for landfall. Once it makes landfall it should get pushed west as the ridge pushes back to the west. So this means it should move inland across the southeast once it makes landfall..

We are not going to make an impact location tracking map yet because we are not certain that this will make it across the island intact. 
We will update this again during the evening later today!

Tropical Storm Chantal Thoughts...

The above two images are images of Chantal. Sometime while we were away from the PC this evening Invest 95 L became Tropical Storm Chantal. This makes this the third storm of the Atlantic Season. 
As you can see by the bottom image which is a water vapor image there is some dry air off to the west of the center of circulation. As long as this dry air does not get  sucked into the C.O.C. we think that conditions are there for Chantal to intensify some. We will take a look at those conditions in just a minute or two but first the latest TRMM pass shows that we have what looks to be a partial eyewall trying to develop.

This next image is the NCEP ensemble forecasts from 18 Z model runs and yes some of these models bring this as a threat to the east coast..Right now we think the most likely target zone would be for this to effect southern Florida...and it will depend on the strength of the Western Atlantic Ridge as to whether or not this can go up the Eastern Seaboard.

The center of circulation currently is under the greatest area of vorticity and the vorticity is not elongated or broad like majority of your systems are when they are developing. 

Wind shear, while important for the development of thunderstorms actually inhibits development of tropical systems and wind shear at this present time is about 10-20 knots .. this does not seem to be having to much of an impact on this system at the present time..

You can see by the shear tendency map which shows where shear is increasing and where it is decreasing that the greatest shear is north of the system and this should work out fine for the time being because the system is generally going to stay on a westward track for the next few days due to the ridging over top of the system as shown on the steering currents map below:

The above image is the convergence map which shows that the greatest convergence lies just south west of Chantal and the greatest divergence also lies just south of Chantal...

As far as the modeling is concerned tonight the GFS takes the system directly over Hispanola as shown here at 69 hrs out...and really keeps the system moving on the fast side. Faster speed of a system can also impede development ...If the GFS is correct with Chantal going over Hispanola then there is a very good chance that the system could be torn apart..

The GGEM tonight brings the system into around the Florida coast line as we mentioned earlier as to where we think the most likely target zone is with this system..

At the time of this writing the ECM is not yet out ...however this was the 12 Z ECM ensemble means ..

So in summary we expect Chantal to continue to slowly organize and intensify with conditions being ideal for intensification and we expect a general west movement the next couple days before a West Northwest track would take place...

At the present time we think Florida has to keep an eye on this system but we also feel that if you are along the east coast you should also be keeping an eye on this system...

We will have another update later on this evening likely in the overnight hours and will include storm track that we think Chantal should take...