7/7 - 10:30pm - Massive Heat Wave Ends with Storms

Today capped off the longest, hottest stretch of weather in Louisville that most people can remember. Today's 106° high at Louisville International Airport was the hottest it's been since July 14th, 1936 when it got to 107°. That temperature is Louisville's all-time record high and if we didn't have as many clouds as we did this afternoon in the city we would have met or broken it. This ends nine days of 100°+ weather, which is the third-longest stretch of triple digits ever recorded according to NWS Louisville.

Storms that will develop tomorrow will be ushering in cooler temperatures, which is welcome news! The bad part is that some of these storms may be severe due to the incredible amount of energy they'll have at their disposal from all the heat. Temperatures in the mid 90's tomorrow with sunshine and high humidity will power an awful lot of instability, or the tendency for air parcels to rise and create thunderstorms. A cold front sinking down from the north that will be stalling out once it passes just to our south will be the focus for storm chances starting tomorrow in the early afternoon in Louisville and lasting through Monday morning.

The main threats from these storms will be wind and hail, but there could also be a threat for some rotating storms too. While winds don't look favorable for any sort of big tornado problems tomorrow, a couple of these rotating storms may get just enough juice to put down a brief spin-up. EHI values in the adjacent image take into account both instability and helicity, which is a product of wind shear. The elevated values you see are powered mostly by instability and just a little bit of helicity, so again, winds aren't that favorable here. The Louisville area is no stranger to summertime tornadoes as you may remember a series of four of them that touched down in late June of last year.

Given the chances for some severe wind and hail tomorrow, the Storm Prediction Center has issued a 15% Slight Risk area for Kentucky. A better chance for severe weather (30%) exists closer to the East Coast where upper-level winds will be stronger as a trough digs down a bit into that area.

6/26 - 10:40am MDT - Another Day, Another State

Yesterday near the Black Hills of South Dakota we saw a few storms develop but they never got organized enough to be good for chasing. One storm in particular had some promise but it just couldn't get strong enough to leave the elevation of the Black Hills where its updraft was rooted. Today we're going north from the Black Hills and moving into North Dakota where there should be a threat for severe storms this afternoon. In particular, areas near and just west of Williston, North Dakota into extreme Eastern Montana appear to be under the greatest threat since a few isolated storms could produce hail, wind, and maybe even an isolated tornado. The Storm Prediction Center only has a general thunderstorm risk for this area but there's a 2% tornado risk included. You'll see the Slight Risk up there in Montana as well in the map to the right, but that area is very remote and the surface winds likely won't cooperate as well for storms like they will in North Dakota.

Winds aloft are forecast to be stronger in our target area today than they were yesterday in South Dakota since the upper-level disturbance over the northwestern part of the country will be moving east a little. When you couple these stronger southwesterly winds aloft with southeasterly winds at the surface that can create some shear for rotating storms. It's worth noting that the best surface winds could be in Canada just north of North Dakota and Montana since an area of low pressure will be spinning winds around from the east there. Since we can't go to Canada, that's obviously out. Dew points in North Dakota are downright soupy this morning and will likely continue to be that way through the afternoon. Having 70 degree dew points right on the Canadian border is something you don't see too often.

With all the warm air and moisture in place, instability will be plentiful for storms. I talked about the threat of isolated tornadoes today on the SPC's outlook and that may very well verify if the instability and shear come together. A great way to combine those two factors is to look at the Energy Helicity Index, which starts getting higher in an isolated spot in Western North Dakota according to the RAP Model. We'll see if it's enough to get some good storms going this afternoon and evening!

Keep up with our chase today by following me on Twitter and Facebook!

6/24 - 10:35am MDT - The Chase Begins!

This morning we're heading toward Cheyenne, Wyoming from Denver as we continue to look at weather data coming in. Today's setup still looks marginal by most accounts, but there are a few small features that could cause a few isolated storms to go severe. For one, surface winds out of the east in Wyoming, Northeast Colorado, and Nebraska will generate upslope flow, which is the lift mechanism we need to get storms going.

These winds will also create some shear because they will be interacting with southwesterly winds at 500 mb (18,000 feet). The issue with this is that the faster winds at this level will be further north toward Rapid City, South Dakota instead of where the more favorable surface winds will be just to the south. In any case, the wind direction at 500 mb will be good enough to usher in the wind shear and maybe some drying of the air at that level to increase instability.

When you put the expected helicity (caused by wind shear) and the instability together for today, you get the Energy Helicity Index (EHI). According to the 14z RAP model, the EHI may try to ramp up a little bit in Northeast Colorado and it even breaks out a little bit of precipitation just west of there too. Surface heating is going to be massive since temperatures will be in the 90's and 100's in some places, so we're hoping this also helps overcome some of the warm temperatures aloft (the cap) so that isolated storms can develop. We're grasping for small features today since there isn't any one thing jumping out to get our attention, but so far it looks like a storm or two could fire on the elevation near Cheyenne. We'll also be watching an area closer to Rapid City, SD to see how things develop up that way.

Follow my continuous chase updates on my Twitter and Facebook accounts today!

6/23 - 11:30pm MDT - Who's Ready to Go North?

Our tour guests have been through orientation and now we're ready to set off for our northward journey tomorrow from Denver to the region where Wyoming, Nebraska, and South Dakota meet. This area will be on the northwestern side of the large ridge in the middle of the country and on the eastern side of the trough coming onshore from the Pacific. This means there will be southwesterly winds aloft, at 500 mb or 18,000 feet, to hopefully bring in some drier air so that instability will increase when it contrasts with the warm, moist air at the surface that will be rising into it. While weak in speed, the winds up there will also increase wind shear because they will be at odds with the easterly and southeasterly winds at the surface. This will increase helicity a little bit, which is a corkscrew-like rotation in the atmosphere that is good for fueling rotating thunderstorms.

Moisture shouldn't be too big of a deal since dewpoints will be in the 60's, but we'll be eying the potential for issues with the the cap, which is a warm layer of air above the surface that inhibits thunderstorm development. All the warm air in place over the central part of the country breeds strong capping since the warm air is in place at the mid levels, but the models are suggesting that this cap may be overcome tomorrow afternoon and lead to some isolated storms. At this point there is nothing that suggests any storm that forms will be anything past marginally severe, but the helicity that the NAM model is picking up on above is certainly worth keeping an eye on.

The Storm Prediction Center has a general thunderstorm risk out for our target area tomorrow with no chance for severe weather. Since storms will be pretty isolated and in a fairly unpopulated area, it may not be worth it for them to issue any sort of severe risk with a setup this marginal. We'll see how things have developed overnight when we set out in the morning though. A secondary low may try to form in western South Dakota tomorrow according to the NAM and that may influence our decision on where to go if it forms since the best winds will be just to the north of the low center. Hopefully we'll see some storms!

Follow me on Twitter and Facebook for the latest tomorrow!

5/25 - 11:50am CDT - A Grand Finale

Ever since earlier this week we've had our eye on today's setup in Central Kansas. The moisture return, a low developing over Southwest Kansas, and upper-level wind support all kept us coming back to look at the models to see how it was shaping up. For a while it looked like the cap, or a layer of instability-inhibiting warm air aloft, was going to surpress storm formation but now we're seeing a situation where there will be just enough break in the cap to allow for a few isolated supercell storms to form. To get surface heating today to break that cap we need to clear out the clouds across Kansas first. A push of dry air at around 10,000 feet is currently moving from Southwest Kansas to the northeast and is eating these clouds for breakfast as you see in the satellite image to the right. We expect this to keep moving throughout the day and hopefully it will clear out the clouds in time to get some serious surface heating going.

The big story here today is the moisture return. For the first time this week we are seeing a situation where dew points will surge into the mid to upper 60's. Yes! This much-needed moisture will be the fuel for storms this afternoon and should give us a much better show than the moisture-deprived low-precipitation storms we've been seeing lately. While we don't have this moisture in the area quite yet, it's streaming in like crazy right now. Strong easterly and southeasterly winds are blowing this moisture into Kansas from Missouri and Oklahoma and will continue doing so throughout the day. Having mostly easterly winds in Kansas right now is a very good thing because this is creating just about optimal low-level shear for rotating supercell storms.

Speaking of wind shear, this will create quite a bit of helicity, or a corkscrew-like rotation of air in the atmosphere. When you combine helicity with instability in an equation you get the Energy Helicity Index (EHI). As I've said before I think that indicies and parameters can be distracting since human analysis is always better than a formula, but EHI seems to be fairly reliable since it is so basic and relies on two very basic ingredients. This afternoon's EHI values in Kansas will be the highest we've seen out here this season according to the Rapid Refresh model. That's some great news for storm chasers because higher EHI values typically correlate with enhanced tornado potential.

The Storm Prediction Center has a Slight Risk for severe storms today from Iowa to the Texas Panhandle and within that a 5% tornado risk in Kansas. This is quite the change from the previously non-severe "general thunderstorm" outlooks that they had been issuing for today because of the concern that strong capping may inhibit storm development. Today is our last chase day out here for Tour 3 and my last day out here until I come back for a week in June. If we could see some good storms today that'd be a great end to the first part of my trip! Tonight once we're finished chasing we'll be traveling back to Oklahoma City where I'll fly back to Louisville from tomorrow morning.

Follow up-to-the-minute reports on our chase on my Twitter and Facebook accounts!

5/22 - 9:45am MDT - Nebraska Here We Come!

Today's storm setup is tricky because we're dealing with, again, a situation where the moisture is not returning to the region as well as we need it to. The good news though is that the trough that is slowly making it's way eastward will finally be in play today, so upper-level wind support will be there for storms. Let's start with the moisture though. The higher dew points will be in the Dakotas today no doubt, but this is at the surface. With such a short time between being dry and having moisture moving into that region, this moist layer is likely very shallow and confined near the surface even though the short-range models this morning show it a little deeper than before (models have not been handling moisture well at all lately). This means that storms up that way would likely be low-precipitation supercells, maybe to the point where some of them are only putting down virga and not ground-falling rain. The better surface wind support near the low will also be in the Dakotas, but you won't get many, if any, tornadoes if the storms can't get any "meat" on them from the lack of moisture. Dew points in Northern Nebraska may be lower at surface, but we may have an overall deeper layer of moisture there.

The upper-level winds as I said before will be more favorable today than yesterday. The trough moving in will provide fast southwesterly winds in the Dakotas extending down to Northern Nebraska. This should bring in some drier air aloft and enhance wind shear for this afternoon's storms. Today we'll stay on the southern end of these winds aloft so that maybe we can get some deeper moisture coupled with the winds. Hopefully some supercell storms can form in this environment.

Because the models are having difficulties resolving moisture issues, today's CAPE (instability) forecast looks rather low in Nebraska with higher values north. This is something we'll be watching throughout the afternoon to see where it actually sets up. The potential lack of moisture and the best shear being removed from deep layer moisture will likely limit tornado potential today, but maybe we can see some high-based photogenic storms!

The Storm Prediction Center has a Slight Risk for severe storms today in the Dakotas extending toward Northern Nebraska. There's only a 2% tornado risk with this and I think this is a good call given the moisture issues here. If dew points were to be higher over a deeper layer in North Dakota I think you could have a pretty decent tornado risk from supercells given the forecast wind environment. In any case, our more southerly target today will put us in great position for tomorrow's chase, which will likely be in Nebraska.

Follow me on Twitter and Facebook for updates today!

5/14 - 12:45pm CDT - Pressing Further Southwest in Texas

Today we're continuing on southwestward in Texas where fast westerly and northwesterly winds aloft and moist, easterly winds at the surface will combine to create a potential for severe weather. These winds should create enough shear for supercells among some scattered storms and more specifically there is a chance for a couple tornadoes down this way. There are a few clouds on the visible satellite view right now from ongoing storms in the region, but areas closer to the Mexican border near Marfa and Fort Davis are pretty much cloud free. There is a field of cumulus clouds we're driving toward south of Marfa that may serve as a focus for development, so we'll see how that pans out. In any case we have lots of direct sunlight and instability already building for storms later this afternoon.

The Storm Prediction Center has issued a Slight Risk for severe weather today across extreme southwest Texas where we're at and they've even included a 5% tornado risk area. This is the best setup we've had so far this week, so we remain hopeful that we'll see some great stuff today! There aren't many roads around the area so this will be a challenging chase day even though the ingredients appear to be coming together pretty well.




Follow me on Twitter and Facebook for the latest today!

5/7 - 10am CDT - On Our Way to South Texas

The same cold front that we targeted yesterday in Kansas and Oklahoma is on the move southward and so are we. We're on our way to South Texas this morning to meet up with where the front, the dry line (boundary between moist air to the east and dry air to the west), surface heating, easterly winds, and moisture all meet up. Storms should fire along the front and/or dry line this afternoon as instability builds. You'll see in the image to the right that there's a sliver of high dew points that will develop in Southwest Texas this afternoon that will be our focus as the cold front moves south.

Due to the threat of severe storms this afternoon, the Storm Prediction Center has issued a Slight Risk area for portions of South Texas with a 2% tornado risk (pictured left). Some of these storms will have large hail and damaging winds. The tornado risk, like yesterday, looks fairly low due to weak winds aloft, but the directional wind shear will help out as well as high instability. There may just be enough ingredients to spawn one or two tornadoes today down there, so we'll cross our fingers and keep driving!

As usual, I'll be posting up-to-the-minute storm chasing updates on my Twitter and Facebook accounts today.

3/31 - 3pm - Severe Risk in West Tennessee

Storms are already popping up in Tennessee as a weak disturbance aloft is allowing the warm, moist air that we have at the surface to rise. A Severe Thunderstorm Watch is in effect for a good deal of West Tennessee until 9pm CDT tonight and the main risks from these storms should they become severe will be large hail and wind. With temperatures aloft being so cold the storms should be able to produce hail easily today. Might want to think about putting your car in a garage or carport if you have one.

Instability is already building across the region as you'll see on the right image. Storms have not really broken out across West Tennessee yet because a weak warm layer aloft known as the "cap" is prohibiting air from rising. Once we get a degree or so warmer that cap should erode and storms will form. This will not be a tornado day because wind shear is very, very weak.

Check out my forecast from this morning on WBBJ below:



Be sure and catch me on 7 Eyewitness News again this evening at 6 and 10 o'clock!

5/30 - 12am CDT - Upslope Storms Part Deux Fell Flat

Our second attempt in chasing upslope storms within a week fell flat today. Like last time, the cap stayed on too tight and a layer of clouds and fog overspread our target area just as we thought storms would initiate. While we waited this afternoon just east of Cheyenne, WY, we ran into Mike Bettes and the Weather Channel's Great Tornado Hunt crew.

The very fog that moved into our target area only grew thicker as we moved into Nebraska to try and limit our driving time needed for tomorrow. At it's thickest point, the fog dropped visibility to around 300 feet as we headed east on I-80. We literally could not see the signs on the side of the road until they were just to the right of the edge of our hood.

Tomorrow could be a pretty big day in the Dakotas and Northern Nebraska. The Storm Prediction Center has issued a Moderate Risk (45%) for portions of the area and expects a few significant tornadoes tomorrow afternoon before the storms merge into a linear line. I'll have an update tomorrow morning when we get on the road, which will be early so that we can get to our target on time.

5/25 - 11:30am CDT - Heading to Eastern Colorado / HIGH Risk East

After a very active day of chasing, we're heading to Eastern Colorado to prepare for tomorrow's risk of upslope storms in that area. Yesterday we drove 362 miles across Oklahoma while chasing and you can see a couple pictures and some video that I shot in the post below.


A HIGH Risk of severe weather has been issued by the SPC for West Tennesee, Western Kentucky, Southeast Missouri, Southern Illinois, Southwest Indiana, and Northwest Arkansas. Just a quick look at some data this morning reveals high dew points and winds backing to the south across the region. The satellite picture is also clear for most of Kentucky and Tennessee, so instability is building quite a bit already this morning. Cities like Jackson and Memphis in Tennessee, Paducah, Owensboro, and Louisville in Kentucky, Jonesboro, Arkansas, St. Louis, Missouri, and Evansville, Indiana need to be on high alert for a possible tornado threat this evening.

5/18 - 9:30am CDT - We're Back to Chasing!

It's been a long start to the week since there haven't been any storms to chase here in the Great Plains. That changes today. We're on our way to Oklahoma in search of tornadoes this afternoon, and I think the potential is looking pretty good considering how things have been this week. Moisture is still going to be an issue, but surface dew points should recover somewhat today. That recovery will take time, so storms may not form until later in the afternoon. Easterly winds at the surface and southwesterly flow aloft at 500mb (18,000 ft) should create ample shear for today's setup, meaning any supercells that form will stay discrete and have the associated tornado risk with them. CAPE or instability shouldn't be a problem based on the modeling for this afternoon and the cap (warm updraft-inhibiting layer of air aloft) should break sometime after 3pm. Given these factors, the Storm Prediction Center has issued a Slight Risk for severe storms this afternoon for much of Southwest Kansas and Western Oklahoma with a 5% tornado risk for the Panhandle region through Southwest Oklahoma.


Be sure to follow my updates on Facebook and Twitter for the latest on our storm chasing adventures this afternoon!

5/17 - 12:45am MDT - Back to Texas Tomorrow!

Surface dew points at 7pm CDT Wednesday from the 0z GFS

We'll be heading back to Central Texas tomorrow so that we can prepare for Wednesday's severe weather risk in that region. The latest 0z model runs (hence the late blog post) have come back with decent results, especially when it comes to the moisture return to the region that we'll need for the Wednesday through Friday's severe weather risks. The NAM and GFS models are both expecting dew points to be in the middle 60's in Central Texas on Wednesday afternoon, which is within the range needed for severe storm development. 500mb winds may not be the best, out of the west-southwest at around 30kt, but that should be enough upper-level support for this "entry-level" event for the week. With the upper wind support, surface heating, and high dew points, instability or CAPE will be in the 2000 J/kg, which again is good enough. These factors plus the presence of the dryline (boundary between moist air in the East US and dry air in the West US) should squeeze out a discrete supercell thunderstorm or two provided that the cap (inhibiting warm layer of air above the surface) doesn't stick around too late. The tornado risk isn't huge because of the higher bases these storms may have, but it's certainly not nonexistent.

We'll plan out an exact target area as we're driving later today and we'll refine it even more tomorrow morning. Thursday and Friday will have higher numbers for these variables across the board, so we can expect an enhanced storm chasing setup then. Should be an interesting mid to late week!

Don't forget to follow me on Facebook and Twitter for the latest chase updates!

5/8 - 7:30am CDT - Heading North This Morning

We'll most likely head north to either Northern Kansas or Southern Nebraska as the severe weather setup in that vicinity seems to be shaping up rather well. The SPC has issued a Slight Risk for most of Nebraska and South Dakota, with a little bit of North Kansas thrown in. A 5% tornado risk has also been issued for this area. An eastward push of the dry line and easterly surface winds up that way should fire off rotating supercells this afternoon provided that enough moisture makes its way northward as advertised on the computer models this morning. A batch of rain is currently moving through the north and east portion of Nebraska, but that should not contaminate our target area.

LCLs (cloud bases) will be very low in North Central Kansas and most of Nebraska, which is always a good thing for tornado development (click right image for LCL forecast). Upper-level winds are not terribly strong (30-35kt at 500mb), but that should be enough to get things going. Storms that form may only move at 10kt this afternoon according to the 6z NAM, and that coupled with about 40kt of bulk shear should make for a batch of slow-moving supercells. CAPE or instability values of over 3000 J/kg will also be crucial to the development of these cells today.

Should anything change dramatically in our target area plans, I'll post a brief update here from the road. Don't forget to follow me on Facebook and Twitter for all the latest reports and photos while we're chasing!

5/7 - 4pm CDT- Hello From Amarillo, TX!

I'm all settled in here at our hotel in Amarillo after a flying in from Louisville. Tonight our tour guests on tour 2 will gather for orientation at a conference room here in the hotel and then we'll go out for a nice dinner before a week of gas station burritos and fast food while chasing.

As a tradition during each tour that departs from Amarillo, the restaurant we'll be eating at is the world-famous Big Texan Steak Ranch. This place is the real deal here in the Texas Panhandle if you're looking for a taste of the stereotypical "Wild West". At the center of the two-floor establishment is an elevated table where diners can try their hand at eating a 72oz steak (with side dishes) within an hour's time. Besides being the spotlight for all the diners at the restaurant, each participant's attempt at eating this behemoth is streamed live online via a video camera mounted on the second floor. It's a fun place and it certainly starts each tour with a lighthearted ice-breaker for everyone.

Tomorrow's target will be a spit decision. Our target area will most likely be somewhere near Wichita Falls, Texas, which is just a few hours drive from Amarillo, or Northern Nebraska (maybe Kansas?). The SPC has a Slight Risk for severe weather posted for West Oklahoma/North Central Texas and Northern Nebraska/Southern South Dakota, but we'll see how everything sets up in the morning before deciding on a specific target area.

The NAM model has a good setup for the Texas/Oklahoma border near Wichita Falls right now with high CAPEs, serviceable wind shear, and decent low-level moisture. The LCLs (Lifted Condensation Level - height of cloud bases) are a little high for my taste at 3000 to 6000ft, which could limit tornado potential in any supercell that fires up. The other chase target in Northern Nebraska/Southern South Dakota (or Northern Kansas based on some of the newest model output) seems to have most of the characteristics of the Texas/Oklahoma one, but LCLs will be slightly lower and shear values could be higher. Those two components alone lead credence to a higher tornado threat, but there's concern that moisture from Texas won't make it up there in time for the advertised severe weather development (see right image - 850mb dew points at 0z Monday). We'll see how it looks in the morning before a final judgement is made!

Be sure to keep up with my updates on Twitter and Facebook for all the latest information while we're chasing tomorrow!

4/14 - 7pm - MS/TN/AL Tornado Outbreak Possible Tomorrow

Severe Weather Setup

A potential tornado outbreak is poised to affect Mississippi, Alabama, and Tennessee tomorrow as a rather potent low and associated trough swing through the central part of the nation. Once a warm front passes through the region tomorrow morning and moisture from the south begins to filter in, all forms of severe weather will be possible in North Mississippi, North Alabama, and West Tennessee. I want to place a particular emphasis on Northeast Mississippi and Northwest Alabama, where the greatest risk of tornadoes appears to be at this time. Large hail and damaging winds are possible across the entire region. The Storm Prediction Center has placed these areas under a 45% Moderate Risk of severe weather for tomorrow.

Keep up with my weather updates on my Twitter and Facebook page.

Timing

Timing is going to be difficult to pin down tomorrow as some computer models have slowed down the overall movement of the system. Areas near the Delta in Mississippi could see severe weather late tonight, but the remainder of the state shouldn't see any until the morning and afternoon hours. Here in Starkville it'll most likely be after 11am when we begin to see supercells pop up on the radar and the risk for severe weather could extend well into the early evening hours. West Tennessee will likely see the risk for severe weather develop after noon and extend to just after sunset. NWS Jackson's timeline on the left is a pretty good guess at when things will develop and where tomorrow.

Details

The SPC's Moderate Risk verifies quite well on the computer model forecasts. Ahead of a surface low in Missouri tomorrow, surface winds will become southeasterly in East Mississippi and West Alabama while upper-level winds (500mb) will be quite strong out of the southwest. This will cause quite a bit of directional and speed shear from the lower levels to the upper levels of the atmosphere that will aid in the creation of rotating supercell thunderstorms. These individual cells will most definitely carry a tornado risk as they develop and roll through tomorrow after the noon hour. Dew points in the mid to upper 60's will aid in the creation of these storms and send instability (CAPE) values well over 1500 J/kg in places.

The SREF model's Significant Tornado Parameter will be at a 4 for most of Mississippi tomorrow, but again the ingredients for tornado creation will most likely be at their prime in the eastern half of the state in the afternoon. West Tennessee won't be at quite the high level of risk that Northeast Mississippi/Northwest Alabama will be in tomorrow due to a lessening of moisture and instability as you head northward, but tornadoes, wind, and large hail are still in play tomorrow afternoon.

I will be driving from Starkville to Jackson, TN tomorrow afternoon in preparation for my Saturday morning show at WBBJ-TV. I am going to try and time my departure so that I can possibly intercept a supercell from its southern side as I drive northward. Storm motions of over 40 mph and the poor road network in Northeast Mississippi aren't good for storm chasing, so that's off the table unless something extraordinary happens.