August 12th Severe Weather Outlook

Stationary front continues to reside across the southeast with a low pressure area over GA. This stationary front runs back west and then runs North to another area of low pressure over the Rockies.

Low pressure and its associated trough are going to start to move East Southeast while another low pressure moving across Canada starts to drop a cold front towards the south..

It will be these fronts that will be the focus for severe weather to occur in the SE and the low pressure with associated trough dropping to the ESE  in the plains states to the south central region.

With shear on the order of 40 Knots plus ..the main primary threat should be straight line winds in excess of 60-70 MPH..

Stay tuned for more information should it become necessary!

What about 93 L?

Folks this is an interesting image. Perhaps you are wondering why this image is so interesting? It is interesting because you see not only 93 L but you also see 92 L and you can see in this image just how close together the two waves actually are.

This makes a forecasting challenge. What happens is you have two tropical waves so close together that they actually fight for supremacy. Sometimes this can cause one to cancel out cause the greatest vorticity is being used by the other etc. So lets see what is going on with 93 L and if you read 92 L ..you basically know since they are in the same location that basically the environment will be the same.

As you can see by the image above 92 L has the greatest vorticity around it as 93 L above represented by the “red I”  is outside of that greatest vorticity area.

Some divergence is occurring with 93 L but the greatest area is still south while it is lacking convergence which the greatest area is off to the west or NW .

Unlike 92 L ..93 L is contending with shear in the range of 20-30 knots. And just like 92 L ..93 L is also surrounded by dry air..

So, the reality of the situation is that 93 L basically has the same problems that have to be overcome by the system in order to develop and it remains to be seen because of the close proximity of the two tropical waves if they do not compete for the available potential to tap into and cancel one or the other out.

Guidance is the same as posted on the previous post and that is the ECM does nothing in the next 48 hrs where as the GFS develops this into a Tropical Cyclone.

Again because the ECM is higher resolution and a more superior model we will lean towards the side of slow development and put the chances at this developing in the next 48 hrs at 10%..

Stay tuned as we will continue to monitor the situation !

Latest look at 92 L in the Tropics

First off we start with the National Hurricane Center and at the realms of the latest update is none other then Stewart. As you can tell by how 93 L increased from 10% to 40 % in the latest updates.

So what we are going to do is we are going to look at 92 L first and we are going to see if we can agree with the 40% chance of development over the next 48 hrs.

We start this tropical tour by looking at a water vapor image of 92 L .

One thing that stands out on that image is the dry air to the west of the system but we can take a closer look into the dry air…

Problem #1

Well this clearly shows that 92 L is ingesting dry air. You want a system to develop this is not something you want to see..

Problem #2

This shows that while the tropical wave is in a good area of vorticity it shows that it is rather stretched out and very broad. Remember a broader, elongated system will take longer to spin up then a more organized compact tropical wave.

Now what you are looking at here is the convergence and divergence. As you can see 92 L has neither convergence or divergence working in its favor at the present time. So this is yet another problem that this system as its developing needs to overcome.

Shear is about 10-20 knots but that’s really not a concern with an anticyclone overhead in the upper levels.

So as you can see from above the environment is not very conducive for development.

You can also see with the latest ECM that over the next 48 hrs it does not really develop the system..

On the other hand the latest GFS does develop 92 L ( along with 93 L).. Being the ECM is a far superior model in the 48 hr and under time frame we are going to have to side with the ECM and put the chances of this developing within the next 48 hrs at no greater then 10%.

As you can tell by this image :

This wave should continue to track off to the west underneath the strong ridge of high pressure…

Next up 93 L and also another look at why either one of these waves could be slower to develop then anticipated by most.

August 11th Severe Weather Potential

Stationary front draped across the Southeast with a low pressure area over Georgia. This stationary front drapes back to the west with another low pressure area over Texas.

Meanwhile another low pressure area and associated front will be ejecting out of the Pacific Northwest and moving towards the east.

It is this frontal system and trough ejecting out of the Pacific Northwest along with the stationary front draped across the southeast that will serve as a trigger or a focus mechanism for the severe weather to occur.

Main primary threats will be hail and winds in excess of 60 MPH. Evening time may be especially active as the lower level jet strengthens across the plains region!

Tropical Update Invest 92 L

The above is a wide view look at the Atlantic Ocean Water Vapor. To the very right of the image in the lower right hand portion of the map is Invest 92 L. Remember this is the invest that was activated that NHC was not even talking about but we were and we put the chances of developing very slim over a 48 hr period.

National Hurricane Center has now chosen to lemonize this with a 10 % chance of development over the next 48 hrs.

Real Wx Services puts the chances of this developing over the next 48 hours at 0%.

Lets look at the surrounding conditions:

Alright from this image we see an anticyclone in place with the invest which means that shear is not going to be an issue even though it is around 10 knots at the present time. This would not be detrimental to development and with the presence of the anticyclone in the upper levels slow development could be possible..HOWEVER…

Another problem that the system is facing is the fact that it is broad and elongated as can be seen by the vorticity image above. That along with the fact that it is still part of the ITCZ. It would have to break away from the ITCZ which means that this will take longer for any system to spin up.

However..that is not the only issue that this invest is facing.

with this image you can see the greatest area of divergence is north or south of the system with no divergence currently. Also the convergence is greatest to the south. But this is just another piece of why this will not develop or have a chance to with in the next 48 hrs. There is an even BIGGER problem that has to be overcome.

This system is surrounded by nothing but dry air. As long as this dry air remains heavy across the invest..it will not be able to develop. That is the biggest problem at this time for the invest to overcome!

Steering currents suggest that this wave should continue to travel towards the west.

Also another factor we have taken into consideration is that the ECM does not develop this within the next 48 hrs.

So to summarize 92 L has some problems that it is facing and needs to over come which the greatest of them is dry air and because of this we feel the chances of becoming a tropical cyclone in the next 48 hrs are 0 %.

We will continue to monitor the situation and update this in another 24 hrs.

August 9th Severe Weather Outlook

The above map is based off the latest SREF and NAM along with the GFS.

CAPE values will be 500-4000 depending on where you are in the zone above

Lift Index will be 0 to – 6 depending where you are located

Mid Level Lapse Rates will be 5.0-7.0 depending where you are located

Shear will be generally 30-50 knots from PA into and thru the south central USA ..

Stationary front just south of Md Stretching from the east to the west to an area of low pressure over  N oklahoma. Another area of low pressure is moving across the southern tier of canada with a warm front pushing east but a cold front draping south thru wisconsin .

Low pressure should develop along this stationary front and move east. Meanwhile the low in Canada will also move east bringing the cold front towards the east. It will be these features along with a trough pushing eastwards that will bring the chance of showers/thunderstorms some of which will be severe into the areas above.

Main severe threats will be winds in excess of 60 MPH and large hail!

Severe Potential August 8th

The above map is based on the latest SREF/NAM/GFS blend.

CAPE is 500-4000 depending where you live in the map above!

Lift Index is 0 to – 10 depending on where you reside.

Lapse Rates are 5.5-7.5 depending where you are located!

One thing that will be lacking is shear unless you are in the south central plains states where there will be 40 knots of shear.

We had a warm front lift thru the NE bringing in some more humid weather and with that came some heavy rains and isolated storms. Currently we have a cold front that is half way thru the state of PA in a west to east type fashion. However to the north of this is yet another front with a low pressure over the lakes and this front also goes back to the west to a low over SE colorado.

It is these fronts that will be crossing the area that will bring with it the chance of showers and thunderstorms but the timing of the front looks to be in the overnight/early morning hours so we are not anticipating much in the way of severe in the PA area. More along the lines of Garden variety storms with heavy rains are possible.

The chance of showers and thunderstorms will be ongoing as it appears multiple s/w’s will develop along this front and it will stall just south of the region. This will keep the area on the receiving end of some potential for wet and perhaps severe weather.

Any storms that do manage to go severe will be capable of hail and straight line winds in excess of 60 MPH and very heavy rain.

The greatest threat of severe should be from Ohio and points to the west and south .

Stay tuned for more information should it become necessary!