Severe Potential April 27th 2013

A cold front will be moving south and east across the state of Texas mainly effecting the eastern part of the state.. To the north of this is a warm front. It is these two fronts that could cause severe weather to occur today in the south along the Gulf Coast region..

Ample shear is in place across the region with at least 40 knots + 

Ample CAPE is also in place with 1000-2500 depending on where you reside ..

There is also decent lift occurring across the region..

Helicity is really a non factor with todays severe weather potential ..

However, the presence of EHI indicates that there could be some super cell activity ..mainly in SW TX and into parts of Louisiana and Mississippi.. 

The main threats today will be winds and Large hail but we can not rule out an isolated tornado in the aforementioned areas above..

Low Risk Severe Potential For April 23rd

A cold front will be making its way east wards across the country today (seems like we just did this about a week ago or less) and this cold front will serve as the trigger to possibly create some severe weather potential.

We have the day pretty much over all as a low risk day which is the equivalent of a see text from SPC.

Temperatures across the region are going to be mainly in the 60s and 70s .. In other words beautiful temperatures for this time of the year and nothing to "hot" .. temperatures behind the front look to fall back into the 50s.

CAPE looks to be quite meager with 500-1000. It should be noted that across this same region shown here the ECM is not showing any CAPE whatsoever ..

Lift index across the area is about -2 to about -4 . 

There is ample wind shear coming in with this cold front as it moves across the country..And EHI would NORMALLY support supercells across KY and TN.. 

However at this time frame there is not yet any moisture into those regions..

Total precipitation across Western TN and Western KY looks to be about a half into to three quarters of an inch of rain. With this being a low risk severe day we think any severe weather that does occur would be isolated and this would be gusty winds and hail in locations that do receive anything severe. Otherwise your main threats will be rainfall . 

A heavy rain event looks like it could be on tap for the southeast over the weekend. We will have more about this as the time gets closer!

April 18th Severe Weather Potential

Keeping in mind yesterdays Storm Prediction Center Outlook for Day 1 had a moderate risk area and a 15% hatched area for tornadoes ..The storm reports look like this so far...

Not one tornado was reported for the day thus far. 

The above is our outlook for today the 18th. Once again the red zone is where we think the greatest risk of severe will be based off the NAM/SREF and ECM ..and also would be the area that would have a chance of a Tornado.

A stationary front goes from off the coast around the carolinas back towards the west across Ohio to Illinois to a low pressure on the Kansas /Missouri border to another area of low pressure around the panhandle of Tx with a cold front trailing off to the SW.. 

The stationary front will lift north as a warm front and the low pressures will move to the NE and  in doing so a cold front will be marching to the east. It is this cold front that will be responsible for another day of severe weather across parts of the USA..
The timing of this cold front looks to be around 06 Z or 2 AM EST (1 AM CDT) across western KY and TN and closer to 8 AM friday morning EST (7 AM ) for central and Eastern Areas of KY and TN..

Due to the timing of this front we think that places in Western to Central KY and TN will be dealing with more in the way of Garden Variety type thunderstorms and heavy rains then actual severe weather. There could be some isolated severe in those regions which would be in the form of gusty winds with the front and possible hail..

12 Z ECM has no CAPE across any of KY or TN and CAPE is one ingredient necessary for severe weather. However ...lets take a look at the severe weather parameters from the NAM..

CAPE is generally 500-1500 which is on the meager side. Generally when one thinks of a severe outbreak they would like to see CAPE in the 2000 + range..

Lift index will be about -4 to -5 but greater across the south around Louisiana 

Shear depending on what time of the day will be 30-50 knots and 60 + knots down across eastern TX but the greatest shear will be further to the west where 90 + will be. 

Helicity a thin stripe stretching from N to S which is in the 500 range ..

EHI +1 or higher again allocated fairly well with the higher Helicity. Now keep in mind this image is at 5 PM in the afternoon ..so those that are in central and western KY and TN are not really dealing with any precipitation at that time frame as the front does not arrive till the overnight hours and by the time the front does arrive the EHI looks like this..

Well below 1 except for locations further to the south .. 
Finally temperatures will be in the 70s and 80s..

So in summary the greatest parameters are actually to the west and south of KY and TN  so we have put the greatest risk to allocate with the greatest parameters. As the storms move towards the east with the cold front they will be going into parameters which are not really conducive for severe weather and with the timing of the front and the heaviest precipitation any storms should weaken and the main threat would be garden variety thunderstorms with heavy rains. In areas to the west they will be looking at Gusty winds along with Large Hail and the potential for tornadoes...

Severe Weather Potential April 17th 2013

Start off with the outlook itself which is posted above . We think the greatest threat for severe weather is going to be from OK then Northeast Into Missouri and East into Ark. This outlook is based on the NAM and the SREF with a blend of the ECM. 

First the culprit responsible for this severe weather event will be a low pressure developing over the OK /TX border and then moving NE from that location with a cold front extending to its south... brief diagram showing this..

As the low pressure moves NE the cold front will press south and off towards the east. As is generally the case the greatest chance of severe is to the North of the area of low pressure and we see this being no different .

There will also be a stationary front draped across the region as well which turns to a cold front once across the  east which was responsible for some of the severe weather which occurred on the 16th.
Once again we think that those located in TX will be spared the greatest severe due to two reasons. 
Reason # 1 is the timing of the cold front which is going to be between 6 Z and 12 Z or 1 AM and 7 AM CDT. 
Reason #2 is that the region is pretty well CAPPED up thru about 30 hrs... This is shown here with the CINH

Which this graph breaks down what those #s mean

CINH

0 - 50	Weak Cap
51 - 199	Moderate Cap
200+	Strong Cap

Also as the enhanced water vapor shows the greatest moisture is actually breaking out over Eastern TX and the eastern GOM..

The image below the satellite is the NAM which shows moisture from hrs 27 to 30 or 10 PM to 1 AM CDT and the moisture is North of the TX /OK border. 

So we strongly believe that the greatest severe weather will be north of that region and this is also based on the parameters as well..

First off its going to be a hot day across the region with temperatures in the 80-90 degree range with dewpoints in the 60s..

Behind the front we will be looking at temperatures cooling into the 50s 

When you have a temperature drop such as shown it generally brings about a severe weather event and this will be no different. 

The red zone is based on the EHI and where there is no CINH to hinder the severe ..

In this same general location the Helicity is quite steep as well..

There is plenty of Lift in the atmosphere ..

And ample enough shear to create the potential for Tornadic activity within the red zone on the map.

This shows as much as 100 knots of shear coming into the region. This is probably over doing it but this is about as extreme as one can get when it comes to wind shear.  CAPE which is like the fuel to add to the fire is also at 1000 or above ..

So we have all severe weather ingredients in place for severe weather to take place across the region. 
Further to the east in locations like KY and TN the risk for severe is much lower due to low parameters in place. However the stationary boundary could act as a trigger for some severe storms where the main threats would be wind and or hail with some heavy rains.

For those in KY and TN your timing looks to be overnight thursday night between 2 AM and 8 AM for the front to cross and garden variety type storms with heavy rains. 

Severe Weather April 11th 2013

We are going to stand in complete contrast to SPC with the Day 2 outlook they has issued yesterday afternoon at 17:30.

As you can see from the current radar you can almost pick out exactly where the cold front is . As all the heavy rain with some garden variety or non severe storms are along the front. 
You can also see this on the surface map as of 11 PM

For the rest of tonight ..there should be heavy rain with nothing more then isolated severe as this batch of rain and the cold front makes its way to the east. It will be crossing western portions of TN and KY between 8 AM and 2 PM in the afternoon. 

And in those areas rain will clear out between 2 PM and 8 PM. 

Nothing is to impressed tonight with severe weather for Thursday. We have the SREF significant severe which looks like this..

Notice how you are missing the dark red other then in the GOM? This is not an impressive map. 

The NAM severe parameters ..CAPE 

The greatest CAPE is over the Southeast and this is at 5 PM right around the peak of daytime heating.

There is also sufficient lift in the atmosphere... 

Helicity is greatest across the Northern Tier ..However ..EHI is only isolated locations of at or above 1..

The greatest parameter in favor of severe would be the shear and this is located over the southern sections..

As the triggers we have a semi quasi stationary front across the northern tier with an impulse or low pressure area traveling across it and across the south we have a cold front that will be making its way towards the east.
With the EHI not very impressive we are not seeing this as a tornado day..perhaps an isolated one here and there but nothing substantial. The main threats will be gusty winds with the front and hail with any of the severe storms..and of course heavy rains.
We are not going with a red zone because of the over all parameters not being impressive enough to warrant a red zone. Greatest potential lies over the Southeast region for the greatest chances of severe weather!