Storm TALK! Monday Edition

2:07 AM UPDATE
Warning cancelled.  No reports of severe weather were noted.

1:43 AM UPDATE

THIS DANGEROUS STORM WAS LOCATED 14 MILES NORTH OF WASHINGTON...OR 25 MILES NORTHEAST OF VINCENNES...MOVING EAST AT 30 MPH.

1:29 AM UPDATE

TORNADO WARNING FOR...
  NORTHERN DAVIESS COUNTY IN SOUTHWEST INDIANA...
  SOUTHEASTERN GREENE COUNTY IN SOUTHWEST INDIANA...
  NORTHEASTERN KNOX COUNTY IN SOUTHWEST INDIANA...
  NORTHWESTERN LAWRENCE COUNTY IN SOUTH CENTRAL INDIANA...
  NORTHERN MARTIN COUNTY IN SOUTHWEST INDIANA...

* UNTIL 215 AM EDT

* AT 120 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS
  STORM WAS LOCATED 11 MILES NORTHWEST OF WASHINGTON...OR 16 MILES
  NORTHEAST OF VINCENNES...AND MOVING EAST AT 30 MPH.

 

10:39 PM UPDATE
Couple quick notes.

SPC has added a SLIGHT RISK for the next few hours as we deal with the warm front lifting northward.  This threat looks isolated with the main concentration likely north of I 64 into IN.  We will watch it.

 

New NAM is in.  It has focused the strong shear a tad east over Kentuckiana.  This does line up with a few other models that are coming in.  Timing looks to be around Midnight -3am right now for tuesday night/wed am.   SPC will issue an outlook update at 2am.

 

 

6:29 PM UPDATE
Tracking a few storms across southern IL. If they hold together, they would arrive after 8pm.  Hail is possible with some of these.     

4:45pm UPDATE
SPC has added a SLIGHT RISK for the start of the MCS late tonight to our west.  Still some question on how strong they would be here locally but the risk is there for a few warnings.  We'll watch it.

 

 

 

Full Post:

Time to break it all down.

Lots to cover for what appears to be a very busy week for Kentuckiana.

TONIGHT

Overview:  A front to our north in an east/west fashion will act as "train tracks" for another MCS to form tonight. This MCS or "cluster of storms" will race along that front across southern Indiana into Ohio.  We will be on the southern edge of this MCS, but the storm risk is there for a few strong storms with high winds/hail with only an isolated tornado threat. We are not outlooked by SPC for this event, but it would not surprise me to see a few warnings being issued with a few of these storms.  Just something to monitor tonight as it develops.

Here is how the NAM sees the MCS:  around 6am

 

And the GFS (more activity a bit further south):  near 6am

 

Keep in mind, only the DAY 1 SPC outlook breaks down the threats of tornadoes/hail/winds. And here they are for tonight's event:

Tornado                                                                Hail                                                   High Winds

                                                       


Taking a Goode Guess:  This not be a widespread event, but there risk is there for some strong to severe storms.  Keep your NOAA radios plugged in for tonight as most of this activity will be late tonight and early tomorrow morning.  We may see isolated activity this evening...esp in Indiana...but nothing strong expected at this time.

TUESDAY NIGHT/WEDNESDAY MORNING

Overview: strong area of low pressure over western MO will pump in moist/warm air into the region. Supercell storms are expected to fire near the St Louis area once the CAP breaks in the afternoon/evening hours.  Tornadoes look likely in this region that includes MO/IL/AR.  These storms will then congeal and form a squall line that will push across KY/IN/TN during the overnight hours into early Wednesday.

SPC has us right now in a MODERATE RISK for this event.

 

Probabilities are at 45% with the blue hatched area meaning a 10% chance of significant severe weather within 25 miles of any point.

 

There is a chance portions of MO/IL/IN could be upgraded to a HIGH RISK in later updates.

Here is their headline about this event:

   ...A SIGNIFICANT SEVERE WEATHER EVENT IS EXPECTED FROM EASTERN
   OKLAHOMA INTO THE OH VALLEY TUESDAY - INCLUDING THE THREAT FOR
   TORNADOES AND DAMAGING WIND/HAIL...

Here is the NAM map for the start of the evening tomorrow evening: 8pm

 

And as the line of storms pass through Kentuckiana: overnight

 

Here is the GFS for the start of the evening tomorrow evening: 8pm (notice it is a bit slower)

 

And as the line of storms pass through Kentuckiana: during overnight (notice it keeps them mostly supercellular)

 

Instability Factors:

NAM
Lifted Index:  near -8 during the day...drops from -2 to -4 during overnight
CAPES: near 2500 during the day... 500 to 1000 during overnight

GFS
Lifted Index: -6 to -8 during the day...drops to -4 during overnight.
CAPES: 2000-2500 during ... 500 to 1000 during overnight

You can see both show plenty of instability for this event...even at overnight. 

But that is only one factor to look at.  What makes this system impressive is the wind fields.  Just like the last historic event over the weekend, the winds changing direction from the surface to a few thousand feet up.  That is what creates a "twisting" motion.   In this case, the signs are there winds will be S/SE at the surface and W/SW aloft.  That is large directional change...aka shear.  When the winds match SW and surface and SW aloft...that usually hints more at a straight-line wind event locally.

So let's look at the winds:

Surface:  Look at the arrows. Due south.

 

Aloft:  Southwest aloft...and very fast!

 

Notice the arrows...tornado threat is there, especially just to our west.

 Taking a Goode Guess:  I think most of the afternoon/evening will be dry with a strong CAP over us.  We will look west in the evening as the supercells fire.  How quickly it becomes a squall line will determine our threats locally.  The winds aloft are strong out of the SW so the storms should push more northeast than due east.  However, any tornadic supercell will likely be a right turner and head more due east.  Highest tornado threat looks west of us in SW IN and W KY.  This may even include our western counties of our viewing area.  That zone could very well end up in the HIGH RISK if it is indeed issued tomorrow.  However, even after the squall-line forms...it will be "wiggly".  I have used this term before, LEWP, for Line Echo Wave Pattern.  This means any bend in the line of storms has the ability to produce a tornado.  So I think the tornado threat is certainly warranted even for the Louisville area.  As the line heads east, straight-line winds will become the main most of severe threats.  Large hail also is possible in the supercells...golf ball size potential.  Timing is what needs to be nailed down better.  I would say anytime after midnight to sunrise will be the main time frame to watch locally from west to east.  Since this is an overnight event, this system becomes more dangerous.  That is why we want to talk about this threat early and often.  I do think just about every county will go under a warning of some sort with this type of event...I just hope no damage takes place or anyone gets hurt.  We have been fairly lucky so far this season...let's hope we luck out again.

 

FRIDAY/SATURDAY

Overview: once again, another situation of a warm front passing through with a low pressure swinging by.  Severe storms will be possible.

GFS for Friday night:

 

Taking a Goode Guess: I don't want to get too specific on this one just yet as we have a lot to get through before we get to this storm...but since it is during a holiday weekend, I wanted to make sure you knew the threat is at least there.  We will watch it.

 

HEAVY RAIN/FLOODING

This could become yet another major headline for us this week.  Take a look at the HPC 5 Day Rainfall Outlook:

 

That would spell out 4-6" of rain for the region from all the storms this week that are forecast.  Flash Flood WATCHES will likely be issued this week at some point.  Keep an eye to the creeks/rivers nearby you if you live by one. 

If you haven't yet, check out our WAVE 3 WEATHER facebook page.  It will be a popular and busy site the next few days as we work to keep you and your family safe!

 ---------------------------------------------------

Early Post:

Items we are tracking today...

1) Hail risk...isolated severe late tonight early Tuesday morning

2) Severe Weather Outbreak late Tuesday night/early Wednesday

3) Severe storm risk late Friday into Saturday

4) Heavy rain/flooding risk from all of the above

I will look over the midday data and post shortly.  Crazy weather week ahead...but what else is new right?!

 

Comments

[Josh]

BG,

I heard from a co worker that one of the tornados this weekend was 3 miles wide. Not sure what state it was in but I know if thats true this is the biggest in the history. 3 miles wide just seems to be a little far fetch. Can you confirm or have you heard this?

Thanks,
Josh

[Brian Goode]

Nope. It was .3 BG.

[AJ]

Lord knows I love to watch a good severe thunderstorm but i dont like the fact there coming in at night which means for me having to stay up. I wish i could go chasing tommorow but I cant i know the storm chasers out in this area will be loving it especially out in illinois missouri and northern arkansas thats where the baddest of the bad storms will probably be.

[Hack]

BG - any idea why the SPC this past SVR event never went to a HIGH Risk for any of the area's involved? Even after it started to evolve they could have changed it. It stayed Moderate Risk the whole time. All of those Tornado and severe criteria reports should have required it, their language in the MD's was strong enough to warrant it dont you think?

Hack

*** Hack--- they did issue a High RISK that afternoon. Here is the link http://www.spc.noaa.gov/products/outlook/archive/2011/day1otlk_20110416_1630.html Allbeit...very late in the outbreak. BG

[Ashley]

Thanks, Brian, as always.

I strongly encourage people to buy a weather radio with an audible alert feature which sounds when a NWS warning is issued. I already had four (four!) weather radios, but not a single one of them had this feature. I bought this type of radio recently, and I feel a tremendous sense of relief. It has a battery back-up in the event the house is without power when it is activated. The audible alert sounds anytime the NWS issues a warning in the area... Including in the middle of the night.

As it was explained in a spotter's class recently by a NOAA meterologist: Most people have smoke detector alarms to protect them while they sleep. It just makes good sense to have an alarm that will alert you to tornadoes while you sleep, also. Air-raid siren warnings are truly lifesavers, but make no mistake: They are best at alerting people who are outside, not people who are in their homes sound asleep.

[Russell]

I really wish kevin would of taken this event coming up on tuesday night more seriously on the news. The way he made it sound it was just going to be a few storms that get warned, when there is a real possibility this system could do alot of damage.

** Actually, I thought Kevin played it up pretty well. He stated the danger of the overnight threat and the SPC outlooks. It is a tough balance in this biz as you don't want to scare people...but you want them to take the threat seriously. - BG

[Kristian]

Hi Brian..how bad do you think Lawrence County Indiana might get tonight and tomorrow night? also what is your email? thanks!
** Hey there... it is too early to get that specific on locations. I think we all have a threat for damaging storms tomorrow night. We will have a much better idea on specifics tomorrow so keep checking back okay? And my email is bgoode@wave3.com BG

[Troy C.]

So basically, don't count on much, if any, sleep tomorrow night. *heavy sigh* How I detest nighttime storms...