A tornado watch is now in effect for portions of Oklahoma and Texas until 8pm Central time this evening.  Looks as if the main threats from these storms will be wind and hail, but an isolated tornado will be possible as low level shear increases this afternoon into the evening hours.  We will continue to monitor the threats and will update you if any of our teams end up hitting the field in this region.

Here is the modeled reflectivity for around 9am tomorrow morning.  You can see a pretty intense shield of precipitation across TN/N MS and N AL.  This area will most likely be in the form of snow as an upper level low pressure area moves across the region.  Very cold temperatures aloft will likely allow this precip to stay in the form of snow through most of the day light hours underneath the low. 

Here is the accumulated snowfall through 9am tomorrow.  The HRRR (High Resolution Rapid Refresh) model is showing some 2-3” totals along the AR/TN/MS border area with more snow still falling at a moderate pace.  You can see the model is showing accumulations sneaking into the picture across North Mississippi and Northwest Alabama during the same time frame.  The snow should just be entering NW sections of Alabama by this time.  We will monitor the trends and progression of this.

We will likely be deploying in the early AM hours for North Alabama to stream somewhere near Monte Sano during the snow event.  This event could drop some couple of inches on the higher elevations across Tennessee and maybe North Alabama.  This will be a situation you will want to pay attention to.  Click the Brett Adair and Eric Parker tab on LiveStormsNOW.com for live video during the event tomorrow.

This is the latest output from the SPC RUC model.  0-1km EHI values are in the 4-6 range across much of Arkansas, North Mississippi and Alabama this evening.  Effective shear values of 500 m*2/s*2 also suggest very strong turning of the winds in the lower levels and could set off a few tornadoes later this evening into tonight.  At the surface….a meso-low of 1004mb may be forming in SW Arkansas by looking at the mass fields.  I would keep the weather radio on in West Alabama tonight just in case some storms do break out ahead of the front and get active.  Don’t be surprised to see some severe storms tomorrow as well with the front hanging around.  Wind/Hail are the main threats, but a tornado could happen too. 

We will watch the situation and post up more information if needed.  We may even chase locally if something breaks early in the morning hours tomorrow.

We will have a full radar summary and video log of our tornado outbreak on last Friday, April 15th online very soon!  Stay tuned.

Brett

LI values in the –3 to –7 range (higher values to the SW) will support a threat of damaging winds with the increased forcing moving in from the west.  Low level shear values will also support updrafts that will keep the line charged across the state, but directional shear will be nearly non-existant.  We will have to watch for kinks in the line for minor spin ups, but the possibility is near zero.

This NAM reflectivity product does just what we think and suggests a line of showers and storms will move through the Birmingham metro during the late afternoon and push through the area during the evening.  Damaging winds up to 65 mph, small hail, and a VERY slim chance at a brief tornado touchdown are possible.  Main threats will be from the wind, lightning, and heavy rainfall.

We have posted up a slight risk of chasing if something does happen to pop and get significant…..especially ahead of the line but we don’t expect much.  Stay tuned for later updates if the situation deserves a closer look.

Some of the latest data is indicating the potential for some supercells capable of producing tornadoes….in particular the 18z GFS and the 12z WRF.  Here is a shot of the reflectivity for 20z tomorrow from the 12z WRF.

This model indicates some isolated development just west of Tupelo which moves towards the NE quickly as the line to the west intensifies.  We think this is a likely scenario where a few rogue cells are able to fire ahead of the line before the winds veer too much and surface convergence is killed before the line plows full.  We expect some pretty significant winds as well with the line which could cause sporadic major damage.  The line won’t be something to take lightly. 

The GFS shows extreme divergence fields over portions of MS/AL by the afternoon and temperatures jumping into the 80°s.  Instability values will be moderate to strong and this will help create a volatile environment.  

LIVE STREAMING VIDEO: CLICK HERE!

The live video will be available via the link above at StormScapeLIVE.com.  We will be streaming beginning around 7am as we move toward the target zone.  As of now, we have one tourist along for the ride tomorrow and have one slot open.  If interested….contact us on our facebook page HERE!

Continue to monitor our twitter feed on the side of the page and our fan page updates when on the road tomorrow.  We will pop in and out of our chat room on the right side of our video stream to chat with you guys as time permits.  See you tomorrow.

The Storm Prediction Center has outlined much of the deep south on Monday and Tuesday for the potential for a significant severe weather threat including hail, high winds, and the potential for some strong tornadoes.  This looks to be the greatest severe threat of the year as we move onward into spring with April marching right in and on cue.  There have been some timing differences, but currently the greatest threat and time for severe weather looks to come between 6pm Monday and 6am on Tuesday.  This has the potential to be a dangerous event.  We will continue to monitor and update later on as conditions warrant. 

This is the latest Day 2 outlook from the SPC in terms of the highest threat of severe weather on Monday.  There is a slight risk in tact for the northern 2/3rd’s of Alabama as well as northeast Mississippi and north Georgia.  The parameters are there for some isolated super cell convection along with the threat of tornadoes.  The tornadic threat will be prevalent with any cells that can form ahead of the line as well as cells embedded within the line.  Shear will weaken with time, but moisture is already outdoing the forecast and can overcome the shear values at times.  We will be updating with our chase target mapping for Monday morning when we plan to deploy as well as updating with our own risk graphics.  However, the SPC does mention the potential for higher probabilities and maybe significant probabilities in later outlooks as the features become more clear. 

Stay with us as we prepare for our first real chase of the 2011 storm season. 

I have a feeling this time tomorrow evening I will probably be sick for not making the trip out to Arkansas, but this is our tornado target product for tomorrow.  This is where we believe the highest potential for a strong, long tracked tornado may be during the afternoon and evening hours across portions of AR/LA/W MS/W TN.  There is definitely some parameters that are coming together for this to be a pretty damaging event.  If something changes and we hit the road, we will let you know first.

Our current high resolution radar shows some lighter showers spreading into the area this hour with the bulk of the rainfall staying south of I-20 where it has remained most of the day.  It looks like some showery activity can be expected for the rest of the night across most of the area with the heaviest rainfall staying to the south.  This will begin to taper off during the day on Monday and give way to mostly cloudy skies.

The Storm Prediction Center in Norman, Oklahoma has issued there latest day 2 convective outlook for Tuesday.  The threat has expanded some to the west and they mention higher instability values potentially being present as temperatures are a big warmer on current model runs for the Mississippi area.  There is now mention of rotating storms with a highly sheared low level environment and the potential for a couple of super cell thunderstorms across LA/MS during this time.  We are going to upgrade our chase status to MODERATE for the likelihood of chasing across the Jackson metro area on Tuesday.  Continue to monitor the blog concerning this as things may change before Tuesday.

Now….we won’t talk much about it but the models are starting to pick up on something pretty big for the weekend.  This is the Canadian model that has performed pretty good in the longer range this winter….and it shows some Winter mischief across Mississippi and Alabama in the form of ice and snow on Saturday.  We will fine tune things before then, but the idea is definitely on the table.

Now….we will look at the current weather maps…

Tempeatures are running in the 40’s and 50’s across the area this evening with clear skies overhead.  We should radiate down into the 30’s with no problem before too much longer.  You will note the spike in temperatures to our west in the Dallas/San Antonio vicinity ahead of our next storm system.  This is setting things up for parts of the southern plains and Midwest to get a rather significant winter storm that is expected to stretch from Oklahoma City to the Great Lakes by Tuesday and Wednesday.

Radar shows some scattered activity breaking out across parts of Texas ahead of the surface front and associated area of low pressure.  The main shortwave is still back over parts of northern Mexico….so it will likely be later tonight before and real established convection gets going and produces anything of significance. 

The SPC has a convective slight risk in place for portions of the SE Texas area mainly for the potential for some wind and hail later in the overnight hours.  This isn’t expected to translate eastward at this point for tomorrow or Monday because we are too dry for any kind of severe weather.

This wave will effect us with some rain late tomorrow night….likely after midnight.  The totals shouldn’t be impressive as the wave will be shearing out across the area and the main precipitation will be decaying.  Totals of less than .25” are generally expected and are advertised by the NAM above.

Now….we are looking into the idea of the second wave that will bring the winter storm across the plains and Midwest possibly setting the stage for some severe weather across the Lower Mississippi Valley region by Tuesday.  The setup involves a strong trough going negatively tilted while intensifying wind fields overspread the area.  The general downfall for these kind of events in the winter is the lack of instability that is associated.  Dynamics can offset instability at times and this could be one of those cases….

These 500mb wind fields are extremely strong and are divergent across the eastern Ozarks and Mississippi Delta region.  This map is valid at 3pm on Tuesday.  The trough is taking a negative tilt as the surface low is beginning to accelerate out of E AR/W MS.  This is a prime setup for severe storms across the deep south.

These shear values of >45+ knots are indicative of very strong low level turning in the atmosphere.  These values are from about 5000ft to the surface.  This indicates extreme shearing will be present in the lower levels of thunderstorms that are able to develop and that they will likely obtain rotation if an updraft can become sustained.  These dynamics will be moving east and northeast.  From this, I do get the idea that damaging winds and potential for some tornadoes will exist across portions of Mississippi and later into West Alabama.

These are the 3km EHI values.  This is an “energy-helicity index” that indicates where the best shear and instability will be present.  Values over 1 are indicative of the potential for significant tornado development.  You can see a bulls eye of near 2 over Natchez, MS at 4pm on Tuesday.  This has been steadily on the rise for the last few model runs as somewhat higher lapse rates and instability values are coming into play.

Finally…here is the forecast sounding from the Jackson, MS area at 3pm off of the 00z NAM model. This shows a very moist column.  The temperature is steadily falling with height and does so pretty rapidly from about 650mb to 300mb.  There is a dry layer there that indicates some potential instability and faster falling temperatures with height.  We will watch for drier air around the 700-750mb level.  This will be key in the formation of deeper instability values.  More dry air at this level can mean less thick cloud cover and higher temperatures in the lower levels creating a “steeper” lapse rate….or cooling of temperature with height.

So, what are we saying?  Basically….I expect the best severe threat to be west of Alabama due to the time of day and nature of the system.  Sure there will be a threat during the overnight Tuesday into Wednesday morning for some isolated damaging winds and maybe a tornado or two, but the better threat sure seems to be over Mississippi at this point.  We are likely going to chase this system if instability parameters continue to improve across the region.  If we can keep the widespread convection at bay….there could be a few tornadoes over there.

We will post more on our plans over the next few days, but for now back to getting the laptop ready for “chase mode” as well as the truck.  Have a good weekend!