Sunday/Monday/Tuessday Severe Weather Outbreak

[TheRef]

So as many of you on here who pay any sort of attention to the weather and such have noticed, this weekend is setting up to be a very productive one as far as severe weather is concerned. For us in Mississippi, we have three days of risk that we will have to worry about. The Storm Prediction Center (SPC) in Norman, OK has released their daily convective outlooks. I'm going to go ahead and post the convective outlooks for Sunday and Monday.
http://www.spc.noaa.gov/products/outlook/day2otlk_0600.gif
^^Sunday^^

http://www.spc.noaa.gov/products/outlook/day3otlk_0730.gif
^^Monday^^

So as you can see, Mississippi is near the action or right in the middle of the action for those two days. The reason why I didn't show Tuesday's risk area is because it is the Day 4 outlook which only shows you the area that they think things will happen. Now I'm going to try and give you a realistic outlook on this weather. Most of the time you will get a meteorologist who will only look at the positives and not the negatives *cough* *cough* Reed Timmer *cough* *cough*. Sorry....had something in my throat. Anyway...let's start off this discussion. This one will DEFINITELY be a lot more in-depth than my usual forecasts since we're talking about a fairly significant events. I'm going to be using a couple of products that I haven't previously used in my discussions but that are relevant for a severe weather situation. I'm going to be using http://weather.cod.edu/forecast/ for my model data. So let's hop right in, shall we?

Sunday April 27, 2014

So as you saw above, the main risk area that SPC is thinking for severe weather is mainly the whole state of Arkansas and dipping down into Northern LA. Now reading the discussion, they are talking about mainly using the NAM for their analysis. That means in SPC's mind the NAM is handling this system the best. I tend to agree with this assessment. With that in mind, the NAM is showing an upper-level trough that is negatively tilted moving towards the Ark-La-Tex. Along with this trough brings a ton of mechanical forcing by way of a jet streak that is moving towards the area. Add in the amount of sunlight that the area will receive before a high amount of cloud cover enters into the area and you have the makings for a fairly significant amount of supercell storms firing up along the middle part of Arkansas. Add in dewpoints in the upper 60's and approaching 70 in some locations and you have plenty of moisture to keep the LCLs fairly low. Low LCL heights are statistically relevant to having an increased tornado possibility when other factors are added in. Around 18Z on Sunday, MLCAPE values are approaching (and sometimes exceeding) 3000 J/kg K. That's a fairly significant amount of MLCAPE for this time of year. 0-3km Helicity values are well over 500 J/kg. Helicity is the amount of rotation on the surface in the horizontal. If you have high helicity values and a lot of CAPE then you can make those tubes of spinning air go vertical and stretch out. When it goes vertical and stretches out the spin increases due to the conservation of angular momentum. Supercell composite values are over 10 which is fairly significant. Significant tornado composite >6.0 which is pointing everything towards us having some strong tornadoes associated with this system on Sunday across Southern AR and Northern LA. Also, surface winds are coming from the SE which is the direction you would most like for tornado genesis because you're going to have that warm, humid air moving into the inflow area of the tornado which will keep it going. 850 mb winds are coming in from the SW which provides a good dry layer. So in my opinion, keep your eye on Southern AR and Northern LA for this event on Sunday.

Monday April 28, 2014

Now we're onto the main event for us. I most likely will try to chase on this day if the setup remains as it is right now. Now it's not looking like it's going to sustain itself as long as the Sunday system. You still have some significant forcing for the beginning of the period. Surface winds from the S/SSW are not what you'd like to see for a tornado event. Dewpoints will peak around the mid 60s which is on the low end of what you'd like to see for low cloud bases. 850 winds coming from the SW and maybe pushing WSW which should provide a dry cap for the energy to have to break. 500 mb winds look to be coming directly from the West which is good to keep the storms moving Westerly. There's a strong ML CAPE gradient that peaks around the Southern part of Mississippi. But I think your main area of instability will be further North towards the 82 corridor. I think your main tornado area is going to be in the Delta, which is what you'd like to see if you're chasing. But I'm not ruling out tornadoes as far South as a line that intersects Hattiesburg and Natchez. Any further South and you're moving out of the main forcing feature in the upper-levels. 0-3 km helicity values aren't as impressive as the day before, only peaking between 400 and 450 J/kg. But like I said earlier, the further you get into the day the more this is going to turn into a linear event and go more towards Straight-line wind damage. So your main tornado threat is the MS Delta and as the day goes on, the tornado threat will decrease and turn more into a straight-line wind threat. But the whole state is going to get some rain with this system, most likely.

If you have any questions or concerns, feel free to comment below or reach me on twitter.

[Martianlander]

Thanks ref. Appreciate the update.

[TheRef]

My buddy, Aaron Castleberry, and I are going to do a Google Hangout to discuss this. Y'all can come on in and watch. We will go live at 7:00 PM CDT.

https://plus.google.com/events/carf33mmfjhvrc7anon1rr95tuo

http://youtu.be/EhxHhbSA1SU

[PassInterference]

Thanks, Ref. Keep us updated.

[starkvegasdawg]

Ref, where are you chasing Monday? I know tomorrow I am basing my chase tomorrow in El Dorado and then seeing what happens as things stand now. For Monday I was just going to wait and see what they are saying then. Really expect SPC to issue a high risk area for tomorrow. Do you care to venture a guess on timing regarding storm initiation tomorrow?

[Dawgfan77]

What time do you expect the rain to hit the Rez area

[DownwardDawg]

My buddy, Aaron Castleberry, and I are going to do a Google Hangout to discuss this. Y'all can come on in and watch. We will go live at 7:00 PM CDT.

https://plus.google.com/events/carf33mmfjhvrc7anon1rr95tuo

http://youtu.be/EhxHhbSA1SU

Ia Aaron wearing a True Maroon shirt?

[slickdawg]

Well, the cap is going to make sure we don't get a drop in Dallas.

[TheRef]

Ia Aaron wearing a True Maroon shirt?

I believe so.

[Bothrops]

So as many of you on here who pay any sort of attention to the weather and such have noticed, this weekend is setting up to be a very productive one as far as severe weather is concerned. For us in Mississippi, we have three days of risk that we will have to worry about. The Storm Prediction Center (SPC) in Norman, OK has released their daily convective outlooks. I'm going to go ahead and post the convective outlooks for Sunday and Monday.
http://www.spc.noaa.gov/products/outlook/day2otlk_0600.gif
^^Sunday^^

http://www.spc.noaa.gov/products/outlook/day3otlk_0730.gif
^^Monday^^

So as you can see, Mississippi is near the action or right in the middle of the action for those two days. The reason why I didn't show Tuesday's risk area is because it is the Day 4 outlook which only shows you the area that they think things will happen. Now I'm going to try and give you a realistic outlook on this weather. Most of the time you will get a meteorologist who will only look at the positives and not the negatives *cough* *cough* Reed Timmer *cough* *cough*. Sorry....had something in my throat. Anyway...let's start off this discussion. This one will DEFINITELY be a lot more in-depth than my usual forecasts since we're talking about a fairly significant events. I'm going to be using a couple of products that I haven't previously used in my discussions but that are relevant for a severe weather situation. I'm going to be using http://weather.cod.edu/forecast/ for my model data. So let's hop right in, shall we?

Sunday April 27, 2014

So as you saw above, the main risk area that SPC is thinking for severe weather is mainly the whole state of Arkansas and dipping down into Northern LA. Now reading the discussion, they are talking about mainly using the NAM for their analysis. That means in SPC's mind the NAM is handling this system the best. I tend to agree with this assessment. With that in mind, the NAM is showing an upper-level trough that is negatively tilted moving towards the Ark-La-Tex. Along with this trough brings a ton of mechanical forcing by way of a jet streak that is moving towards the area. Add in the amount of sunlight that the area will receive before a high amount of cloud cover enters into the area and you have the makings for a fairly significant amount of supercell storms firing up along the middle part of Arkansas. Add in dewpoints in the upper 60's and approaching 70 in some locations and you have plenty of moisture to keep the LCLs fairly low. Low LCL heights are statistically relevant to having an increased tornado possibility when other factors are added in. Around 18Z on Sunday, MLCAPE values are approaching (and sometimes exceeding) 3000 J/kg K. That's a fairly significant amount of MLCAPE for this time of year. 0-3km Helicity values are well over 500 J/kg. Helicity is the amount of rotation on the surface in the horizontal. If you have high helicity values and a lot of CAPE then you can make those tubes of spinning air go vertical and stretch out. When it goes vertical and stretches out the spin increases due to the conservation of angular momentum. Supercell composite values are over 10 which is fairly significant. Significant tornado composite >6.0 which is pointing everything towards us having some strong tornadoes associated with this system on Sunday across Southern AR and Northern LA. Also, surface winds are coming from the SE which is the direction you would most like for tornado genesis because you're going to have that warm, humid air moving into the inflow area of the tornado which will keep it going. 850 mb winds are coming in from the SW which provides a good dry layer. So in my opinion, keep your eye on Southern AR and Northern LA for this event on Sunday.

Monday April 28, 2014

Now we're onto the main event for us. I most likely will try to chase on this day if the setup remains as it is right now. Now it's not looking like it's going to sustain itself as long as the Sunday system. You still have some significant forcing for the beginning of the period. Surface winds from the S/SSW are not what you'd like to see for a tornado event. Dewpoints will peak around the mid 60s which is on the low end of what you'd like to see for low cloud bases. 850 winds coming from the SW and maybe pushing WSW which should provide a dry cap for the energy to have to break. 500 mb winds look to be coming directly from the West which is good to keep the storms moving Westerly. There's a strong ML CAPE gradient that peaks around the Southern part of Mississippi. But I think your main area of instability will be further North towards the 82 corridor. I think your main tornado area is going to be in the Delta, which is what you'd like to see if you're chasing. But I'm not ruling out tornadoes as far South as a line that intersects Hattiesburg and Natchez. Any further South and you're moving out of the main forcing feature in the upper-levels. 0-3 km helicity values aren't as impressive as the day before, only peaking between 400 and 450 J/kg. But like I said earlier, the further you get into the day the more this is going to turn into a linear event and go more towards Straight-line wind damage. So your main tornado threat is the MS Delta and as the day goes on, the tornado threat will decrease and turn more into a straight-line wind threat. But the whole state is going to get some rain with this system, most likely.

If you have any questions or concerns, feel free to comment below or reach me on twitter.

Thanks Ref. I'm getting an education here.

[TheRef]

Thanks Ref. I'm getting an education here.

That's my goal, buddy. Educate the masses.

[DownwardDawg]

BTW, I enjoyed the live youtube thingamajiggie.

[TheRef]

Bump for update.

SPC has tilted the outlook area for Monday. Take a look:

http://www.spc.noaa.gov/products/outlook/day2otlk_0600.gif

So SPC has put in their discussion that there is a likely chance of several strong tornadoes and widespread damaging winds associated with this system. This is definitely a system not to mess around with. Now I'm not telling you this to send you into a panic or have you running to everyone at church and tell them that I said there's going to be EF-5 tornadoes dropping down everywhere. PLEASE do not take it as such. I'm telling you this to have you be prepared. If you have time, please go get a weather radio and make sure you and your family have a plan in place if a tornado were to happen. Make sure everyone knows where to go, what to do, etc. Maybe do a dry run on it. But just stay prepared with this and have multiple lines of communication.

[Will James]

What's the outlook look like for the 82 corridor between Winona and Tuscaloosa this afternoon

[TheRef]

What's the outlook look like for the 82 corridor between Winona and Tuscaloosa this afternoon

Just rain for about 2 more hours, maybe a severe thunderstorm or two for hail/high winds. The rest of the severe weather will come in around midnight tonight.

[PassInterference]

I don't speak Zulu. What does 281200Z mean?

[TheRef]

I don't speak Zulu. What does 281200Z mean?

April 28 at 12Z (7:00 AM)

[DownwardDawg]

Thanks because I had no freakin idea what that was either!

[TheRef]

Thanks because I had no freakin idea what that was either!

That is Zulu or Greenwich Mean Time. It makes it easier for Meteorologists to communicate times to each other and across time zones.

[Drugdog]

Dang I see why I graduated in Business. My party life at the pike house would have suffered greatly. Excellent work fellow Delta brother.

[DownwardDawg]

Ref,
How about timelines? I work away and I use info like this to help keep my wife and kids updated. They are in Lamar and Covington county. Will there be a tornado threat in the Lamar county area during school hours Monday? How about Tuesday? Is the biggest threat tomoorow night?
Thanks for all these threads. I love them. You do a good job keeping us informed. It's amazing how little I know about weather and weather patterns, yet I know about 1,000,000 x more than my wife and kids!

[TheRef]

Ref,
How about timelines? I work away and I use info like this to help keep my wife and kids updated. They are in Lamar and Covington county. Will there be a tornado threat in the Lamar county area during school hours Monday? How about Tuesday? Is the biggest threat tomoorow night?
Thanks for all these threads. I love them. You do a good job keeping us informed. It's amazing how little I know about weather and weather patterns, yet I know about 1,000,000 x more than my wife and kids!

Tuesday seems to have dropped off dramatically as far as threat is concerned for us. Monday looks to be our main risk. I'm not going to a put a timeline on this tornado risk, though. I would put the tornado threat for most of the day, buddy, for Lamar.

[Barking 13]

Ref, do you recommend any of the weather apps? I mean for severe weather warnings like a WXR

I've got TWC, Spann, Red Cross, and NOAA

[PassInterference]

I use Wx Alert USA. The alarms from it are completely programmable. You can choose what kind of watches & warnings you want to be alerted to. You can choose what counties you want to be alerted to.

I've got mine set up to give me tornado watches & warnings and severe t-storm watched & warnings in my 3-county area. The sound for the alarm sounds just like the NWS sound you hear on the radio.

But setting it up is not very user friendly.

[hells bells]

So as many of you on here who pay any sort of attention to the weather and such have noticed, this weekend is setting up to be a very productive one as far as severe weather is concerned. For us in Mississippi, we have three days of risk that we will have to worry about. The Storm Prediction Center (SPC) in Norman, OK has released their daily convective outlooks. I'm going to go ahead and post the convective outlooks for Sunday and Monday.
http://www.spc.noaa.gov/products/outlook/day2otlk_0600.gif
^^Sunday^^

http://www.spc.noaa.gov/products/outlook/day3otlk_0730.gif
^^Monday^^

So as you can see, Mississippi is near the action or right in the middle of the action for those two days. The reason why I didn't show Tuesday's risk area is because it is the Day 4 outlook which only shows you the area that they think things will happen. Now I'm going to try and give you a realistic outlook on this weather. Most of the time you will get a meteorologist who will only look at the positives and not the negatives *cough* *cough* Reed Timmer *cough* *cough*. Sorry....had something in my throat. Anyway...let's start off this discussion. This one will DEFINITELY be a lot more in-depth than my usual forecasts since we're talking about a fairly significant events. I'm going to be using a couple of products that I haven't previously used in my discussions but that are relevant for a severe weather situation. I'm going to be using http://weather.cod.edu/forecast/ for my model data. So let's hop right in, shall we?

Sunday April 27, 2014

So as you saw above, the main risk area that SPC is thinking for severe weather is mainly the whole state of Arkansas and dipping down into Northern LA. Now reading the discussion, they are talking about mainly using the NAM for their analysis. That means in SPC's mind the NAM is handling this system the best. I tend to agree with this assessment. With that in mind, the NAM is showing an upper-level trough that is negatively tilted moving towards the Ark-La-Tex. Along with this trough brings a ton of mechanical forcing by way of a jet streak that is moving towards the area. Add in the amount of sunlight that the area will receive before a high amount of cloud cover enters into the area and you have the makings for a fairly significant amount of supercell storms firing up along the middle part of Arkansas. Add in dewpoints in the upper 60's and approaching 70 in some locations and you have plenty of moisture to keep the LCLs fairly low. Low LCL heights are statistically relevant to having an increased tornado possibility when other factors are added in. Around 18Z on Sunday, MLCAPE values are approaching (and sometimes exceeding) 3000 J/kg K. That's a fairly significant amount of MLCAPE for this time of year. 0-3km Helicity values are well over 500 J/kg. Helicity is the amount of rotation on the surface in the horizontal. If you have high helicity values and a lot of CAPE then you can make those tubes of spinning air go vertical and stretch out. When it goes vertical and stretches out the spin increases due to the conservation of angular momentum. Supercell composite values are over 10 which is fairly significant. Significant tornado composite >6.0 which is pointing everything towards us having some strong tornadoes associated with this system on Sunday across Southern AR and Northern LA. Also, surface winds are coming from the SE which is the direction you would most like for tornado genesis because you're going to have that warm, humid air moving into the inflow area of the tornado which will keep it going. 850 mb winds are coming in from the SW which provides a good dry layer. So in my opinion, keep your eye on Southern AR and Northern LA for this event on Sunday.

Monday April 28, 2014

Now we're onto the main event for us. I most likely will try to chase on this day if the setup remains as it is right now. Now it's not looking like it's going to sustain itself as long as the Sunday system. You still have some significant forcing for the beginning of the period. Surface winds from the S/SSW are not what you'd like to see for a tornado event. Dewpoints will peak around the mid 60s which is on the low end of what you'd like to see for low cloud bases. 850 winds coming from the SW and maybe pushing WSW which should provide a dry cap for the energy to have to break. 500 mb winds look to be coming directly from the West which is good to keep the storms moving Westerly. There's a strong ML CAPE gradient that peaks around the Southern part of Mississippi. But I think your main area of instability will be further North towards the 82 corridor. I think your main tornado area is going to be in the Delta, which is what you'd like to see if you're chasing. But I'm not ruling out tornadoes as far South as a line that intersects Hattiesburg and Natchez. Any further South and you're moving out of the main forcing feature in the upper-levels. 0-3 km helicity values aren't as impressive as the day before, only peaking between 400 and 450 J/kg. But like I said earlier, the further you get into the day the more this is going to turn into a linear event and go more towards Straight-line wind damage. So your main tornado threat is the MS Delta and as the day goes on, the tornado threat will decrease and turn more into a straight-line wind threat. But the whole state is going to get some rain with this system, most likely.

If you have any questions or concerns, feel free to comment below or reach me on twitter.

Simply outstanding Ref.

[TheRef]

Ref, do you recommend any of the weather apps? I mean for severe weather warnings like a WXR

I've got TWC, Spann, Red Cross, and NOAA

I use Alert FM...but that's just me.

[DownwardDawg]

Tuesday seems to have dropped off dramatically as far as threat is concerned for us. Monday looks to be our main risk. I'm not going to a put a timeline on this tornado risk, though. I would put the tornado threat for most of the day, buddy, for Lamar.

Thanks Ref!!

[civilengineerdog]

thanks!

[TheRef]

thanks!

Yupp.....

[poposay]

Yupp.....

the bad stuff will be here early tomorrow morning? Tornadoes too?

[TheRef]

the bad stuff will be here early tomorrow morning? Tornadoes too?

Not necessarily...

[DownwardDawg]

Not necessarily...

Hahaha!! Spoken like a true meteorologist! (or politician)

[TheRef]

Hahaha!! Spoken like a true meteorologist! (or politician)

The reason why is because I don't want y'all looking at your watch and saying "Oh...it's past so-and-so so we're safe...."

[poposay]

The reason why is because I don't want y'all looking at your watch and saying "Oh...it's past so-and-so so we're safe...."

I get that. Just wanted to know if I need to have the wife and kids hang here where we have a storm shelter or can they go do their morning routine stuff (gym, library etc)

[Rick Danko]

Call me crazy but based on NOAA radar it appears this line may move north of the 82 corridor. Ref, at this time is do you feel the delta is still the main line of activity or does it appear to be moving north to you?

[TheRef]

I still believe the Delta will be the main line of activity for this evening/tomorrow. Also, I'm asking if y'all will please send prayers up for those affected by this tornado in Arkansas right now. Vilonia, AR Police are reporting a mass casualty situation and are requesting as many EMTs as possible to be en route to the area...this thing started just west of LR and has trekked all the way over to the Arkansas delta....this thing is just nasty and is causing havoc. This is why we try to have y'all have a plan and multiple forms of communication in place.

[TheRef]

This is I-40 near Conway. Be warned, this is hard to watch and made my skin crawl. THIS is what people in AR are having to deal with right now and we may have to deal with tomorrow. This is no joke.

https://t.co/NPmKpLC5jE

[DawgSaint]

This is I-40 near Conway. Be warned, this is hard to watch and made my skin crawl. THIS is what people in AR are having to deal with right now and we may have to deal with tomorrow. This is no joke.

https://t.co/NPmKpLC5jE

Wow! Hard to watch that! Prayers for the safety for all in path of this system over next two days!

[DownwardDawg]

This is I-40 near Conway. Be warned, this is hard to watch and made my skin crawl. THIS is what people in AR are having to deal with right now and we may have to deal with tomorrow. This is no joke.

https://t.co/NPmKpLC5jE

Wow. Terrible.

[TheRef]

Preliminary reports of 8 dead.....many others injured....houses wiped clean off of the foundations.

[TheRef]

Today is looking like a two-wave event. Right now we have the first wave coming through the Delta and North-Central MS. In about 6 hours or so, the second wave will start coming through. This second wave will be our big tornado threat. Also, SPC is considering upgrading MS to a high-risk. Also, the latest model output seems to suggest that the Golden Triangle may be the bullseye for severe weather this afternoon/evening. If we start having night storms, our risk increases dramatically due to the fact that we can't visually watch it as well.

[TheRef]

Here is what the SPC is thinking:

Full outlook

http://www.spc.noaa.gov/products/outlook/day1otlk_1300.gif

Tornado probability

http://www.spc.noaa.gov/products/outlook/day1probotlk_1300_torn.gif

Severe Wind Probability

http://www.spc.noaa.gov/products/outlook/day1probotlk_1300_wind.gif

Severe Hail Probability

http://www.spc.noaa.gov/products/outlook/day1probotlk_1300_hail.gif

As you can tell, the main threats are tornadoes and hail, which makes sense with a lot of CAPE and forcing.

[lefty96]

I drove through the Mayflower, AR damage on the way to work this morning - what a mess - never seen anything like that.