A few showers are ongoing across West Tennnessee right now, but this is quite a bit less than what was expected today. Dry air rotating around a area of high pressure has moved into the region because this high has nudged a bit further westward than originally forecast. This means that a majority of the shower activity has stayed west of the Mississippi River, but a couple thundershowers could still pop up before sunset. These should mostly dissipate before the overnight hours.
Heat and humidity are on their way back as a large ridge of high pressure moves eastward over the next few days. This should surpress storm chances a little bit, but not entirely because temperatures aloft will still be a little cool. This heat at the surface and the slightly cool air aloft should create the typical "summertime pop-up storm" environment that we're used to seeing in the afternoons this time of year. Temperatures underneath this ridge of high pressure should be in the lower to middle 90's in West Tenneessee and middle 90's until Wednesday in Kentuckiana. A front dropping south on Thursday will trigger higher rain chances in both Kentuckiana and West Tenneessee and there could be some slightly cooler temperatures behind the front for Kentuckiana. Things look to remain hot all week long in West Tennessee!
I'm in Jackson, TN right now getting ready for the 10 O'Clock news on WBBJ this evening before going back to Louisville tomorrow. Check out my Hokey Weather Fact from last night's show on the left and be sure to tune in to WBBJ tonight at 10 for a new one!
Showing posts with label heat wave. Show all posts
Showing posts with label heat wave. Show all posts
Sunday, July 15, 2012
Saturday, July 7, 2012
7/7 - 10:30pm - Massive Heat Wave Ends with Storms

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.

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.
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Thursday, July 5, 2012
7/5 - 11:30pm - Louisville Urban Heat Island This Week
It goes without saying that it's been incredibly hot this week in Louisville. This is all thanks to an expansive ridge of high pressure over the center of the country. High temperatures have been record-breaking every day this week except Tuesday when the high at the airport was below 100. This stretch of triple digit temperatures dates back to June 28th and there appear to be at least two more days of 100-plus weather ahead. The urban heat island effect, which causes temperatures in concrete and asphalt-filled urban areas to be higher than more vegetated suburban and rural areas, has been pretty apparent with the extreme heat. Temperature readings at Louisville International Airport have been consistently higher than other observation sites within the city and this is easy to see when comparing the high and low temperatures for each day this week with surrounding stations. Below you'll find the high and low temperatures for each day of the week so far at Louisville International Airport (KSDF), a personal weather station in Shively (West Louisville), Bowman Field, and a personal weather station in Fisherville (East Louisville):
Thursday July 5th
Louisville Airport 104/78 | Shively 100/72 | Bowman 102/78 | Fisherville 98/72
Wednesday July 4th
Louisville Airport 102/76 | Shively 101/76 | Bowman 99/76 | Fisherville 97/69
Tuesday July 3rd
Louisville Airport 97/73 | Shively 97/73 | Bowman 96/72 | Fisherville 93/67
Monday July 2nd
Louisville Airport 100/73 | Shively 99/73 | Bowman 99/71 | Fisherville 96/67
Sunday July 1st
Louisville Airport 103/74 | Shively 102/75 | Bowman 101/72 | Fisherville 99/70
I've sorted the data above from most urban (the airport) to least urban (Fisherville), so it's not hard to put together that temperatures generally decrease as you get further away from the dense center of Louisville. The Fisherville observation station is located in a valley in the eastern portion of the county, so the low temperatures each morning are a bit cooler than they would be otherwise due to cool air settling into the valley at night. High temperatures at this station shouldn't be affected by the valley and this checks out because I've been keeping an eye on the observations in Shelbyville, which is down the street from Fisherville, so to say. This warmth due to the urban heat island near the airport is significant because this is where the official temperatures for the city are taken. If it's 100 degrees at the airport, the rest of the city is probably seeing temperatures a degree or two cooler.
This difference in temperature between the airport and the rest of the city was the focus of some research I published in April for a class at Mississippi State University. I used quite a bit of historical data to figure out how much the urban heat island "distorts" the temperatures at the airport. Go check out my research by clicking this link to a blog post I penned earlier this year.
Thursday July 5th
Louisville Airport 104/78 | Shively 100/72 | Bowman 102/78 | Fisherville 98/72
Wednesday July 4th
Louisville Airport 102/76 | Shively 101/76 | Bowman 99/76 | Fisherville 97/69
Tuesday July 3rd
Louisville Airport 97/73 | Shively 97/73 | Bowman 96/72 | Fisherville 93/67
Monday July 2nd
Louisville Airport 100/73 | Shively 99/73 | Bowman 99/71 | Fisherville 96/67
Sunday July 1st
Louisville Airport 103/74 | Shively 102/75 | Bowman 101/72 | Fisherville 99/70
I've sorted the data above from most urban (the airport) to least urban (Fisherville), so it's not hard to put together that temperatures generally decrease as you get further away from the dense center of Louisville. The Fisherville observation station is located in a valley in the eastern portion of the county, so the low temperatures each morning are a bit cooler than they would be otherwise due to cool air settling into the valley at night. High temperatures at this station shouldn't be affected by the valley and this checks out because I've been keeping an eye on the observations in Shelbyville, which is down the street from Fisherville, so to say. This warmth due to the urban heat island near the airport is significant because this is where the official temperatures for the city are taken. If it's 100 degrees at the airport, the rest of the city is probably seeing temperatures a degree or two cooler.
This difference in temperature between the airport and the rest of the city was the focus of some research I published in April for a class at Mississippi State University. I used quite a bit of historical data to figure out how much the urban heat island "distorts" the temperatures at the airport. Go check out my research by clicking this link to a blog post I penned earlier this year.
Thursday, August 4, 2011
8/4 - 11:30am - Finally, a Break in Sight!
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Ridge breaking at 500mb on Wed. |

Talk of development in the tropics has come to a fever pitch lately as Tropical Storm Emily seems to be taking a path that will pass very close to the southeast coast of Florida. The forecast path has been flip flopping around a little bit over the last couple of days, but at least right now it appears that Florida will not see a landfall from this storm. Emily has sustained winds at 50 mph, which is still a ways from the 74 mph needed to be declared a hurricane. The National Hurricane Center's forecast includes Emily reaching hurricane status by Monday well off the coast of South Carolina.
Saturday, July 23, 2011
7/23 - 1:15pm - Heat Continues, No End in Sight
The entrenched heat we've had over the eastern half of the nation has been making headlines for quite some time now and it appears that it will continue for a while more. The strong ridge of hot, stagnant air is staying firmly in place and most forecast models are keeping it over the same area for at least the next week or two. A big portion of the Plains, Midwest, and East Coast is covered in heat advisories and warnings, which you'll see shaded in orange and purple on left.
Around Louisville, temperatures are going to stay in the 90's for the foreseeable future. For some perspective, we're hotter right now than Jackson, MS, Birmingham, AL, Memphis, TN, Jackson, TN, and Nashville, TN. Cloud cover, surface winds bringing in cooler air, and easterly flow aloft is keeping these locations cooler than Louisville even though they're all to the south. This really highlights the Midwest and Plains as being the primary target for the heatwave since we have been and will continue to be feeding off of the entrenched hot air from those regions.
A few pop-up showers and storms are possible today in Louisville, but a bigger chance for storms comes tomorrow as a "cool" front approaches the area that will cross through on Monday. I think tomorrow afternoon and evening will be the best time period for storms, most likely lasting into the early part of Monday. Behind this "cool" front temperatures won't really drop much, but dew points will take a tumble.
Check out the dew point output from the GFS for early Wednesday on the left. Those dew points are a good 15 degrees lower than the average this week and that translates to markedly lower humidity. That won't last long though... higher dew points with the same old hot temperatures will be back before the weekend. Until then, remember that an Excessive Heat Warning continues for the Louisville area until Sunday night. Stay safe!
Around Louisville, temperatures are going to stay in the 90's for the foreseeable future. For some perspective, we're hotter right now than Jackson, MS, Birmingham, AL, Memphis, TN, Jackson, TN, and Nashville, TN. Cloud cover, surface winds bringing in cooler air, and easterly flow aloft is keeping these locations cooler than Louisville even though they're all to the south. This really highlights the Midwest and Plains as being the primary target for the heatwave since we have been and will continue to be feeding off of the entrenched hot air from those regions.
A few pop-up showers and storms are possible today in Louisville, but a bigger chance for storms comes tomorrow as a "cool" front approaches the area that will cross through on Monday. I think tomorrow afternoon and evening will be the best time period for storms, most likely lasting into the early part of Monday. Behind this "cool" front temperatures won't really drop much, but dew points will take a tumble.

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Thursday, July 21, 2011
7/21 - 2pm - Enough Excessive Heat to Go Around

Heat Index?
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NC State Climate Office |
I've been mentioning the term heat index for weeks now, so what exactly is the heat index you ask? Most people know it as the "feels like" temperature or what it feels like because of the humidity. That's basically it in a nutshell, but there's more to it. Mathematically, the heat index is a product of an equation that uses temperature and relative humidity. Factors like perspiration and body size averages are held constant, so the heat index is an educated guess at the "temperature" that most people are feeling. Don't let the "educated guess" usage fool you though, because higher humidity and in turn heat index values lessen the amount of evaporational cooling on your skin. If your body can't cool properly through this evaporation, you can overheat quite easily. It's interesting and useful to note that heat index values are based on what it feels like in the shade. Being in the sun can increase the heat index by up to 15°. Below is a table from NWS Pueblo, CO with heat index values and associated heat disorders:
With the heat we'll have a chance for afternoon scattered storms, which will increase significantly as we get closer to the passage of a cold front on Monday. Today's storms have been and should be staying south of Louisville, so we'll see no relief from the heat today!
Monday, July 18, 2011
7/18 - 12pm - Heat, Storms on the Way this Week

![]() |
Disturbance over IN at 700mb |

Let's not forget about the heat! The National Weather Service has issued an Excessive Heat Watch along and west of I-65 from Tuesday afternoon to Friday evening due to heat index values reaching up to 110 degrees. Actual forecast highs in Louisville will be in the mid to upper 90's throughout the week, so get ready for an extended heat wave. Humidity won't be as extreme as last week, but even so we'll be seeing dew points getting into the mid 70's near the latter part of the week. Uncomfortable humidity starts with a 60 degree dew point, so you can imagine that mid 70's are pretty bad!
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Saturday, July 16, 2011
7/16 - 11am - Heat Building Back In
![]() |
Ridge over Central US on Wednesday |
![]() |
Thursday Eve. temperatures (GFS) |
GFSX MOS (MEX) KSDF GFSX MOS GUIDANCE 7/16/2011 0000 UTC FHR 24| 36 48| 60 72| 84 96|108 120|132 144|156 168| SAT 16| SUN 17| MON 18| TUE 19| WED 20| THU 21| FRI 22| X/N 89| 73 93| 75 95| 78 96| 79 98| 78 99| 78 97| TMP 85| 75 88| 77 90| 80 91| 81 92| 80 93| 80 91| DPT 69| 70 69| 72 70| 75 74| 75 72| 72 71| 71 70| CLD PC| PC PC| CL PC| PC PC| PC PC| PC PC| PC PC| WND 6| 6 7| 6 9| 9 9| 9 8| 7 8| 7 8| P12 24| 13 14| 7 9| 19 40| 27 20| 12 25| 14 19| P24 | 19| 9| 40| 40| 25| 34| Q12 0| 0 0| 0 0| 0 1| 0 0| 0 0| 0 | Q24 | 0| 0| 1| 1| 0| | T12 26| 8 32| 10 24| 37 49| 49 39| 29 28| 21 36| T24 | 30 | 40 | 50 | 71 | 49 | 44 |
Looks pretty hot doesn't it? A span of three or more 90 degree plus days is usually considered a heat wave, so I think we'll meet and exceed that definition easily. Next week will be a good time to take it easy and drink lots of fluids when working or playing outside. Here comes the heat!
Tuesday, July 12, 2011
7/12 - 10am - Another Day of Incredible Heat



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Monday, July 11, 2011
7/11 - 6:45pm - It's So Hot You Can (sorta) Fry an Egg!
It's 96° outside in Louisville with a heat index of 114°, making this the hottest day of the year so far. This got me thinking: Is it hot enough to fry an egg outside? I grabbed an infrared thermometer (measures temperature without having to make contact with the surface) and did some tests to see how hot various surfaces around my house were. The wooden deck was 149.3°, the tan concrete of our patio was 130.6°, and our driveway was 129.5°. While all very hot surfaces with direct sunlight, the deck was a clear winner.
Now to the egg frying part. I didn't want to fry an egg on the surface of the wooden deck because it may stain it. So, I put a metal cookie sheet right on top of the deck surface. This not only protects the deck, but easily heats up in the direct sunlight. After a few minutes in the sun, the temperature of the cookie sheet with non-stick spray applied about equaled the temperature of the deck surface.
Since the refrigerator at my house was void of eggs, I poured out the one-egg equivalent of egg beaters, the made-from-eggs substitute that you find at the grocery store, into a measuring cup. This may have thrown my results a bit, but hey, this is supposed to be fun right? Once the cup of egg beaters warmed to the ambient air temperature (around 96°), I poured it out on to the cookie sheet.
The results were interesting. I spread the liquid eggs around on the pan to resemble a flat pancake or crepe to increase surface area for heating. After a few minutes the edges of this "pancake" turned crispy and the middle became a thicker liquid with solid "chunks" (yeah, don't read this if you're getting ready to eat dinner) embedded in it. The surface of the deck was cooling down just before five o'clock, so this marked the end of the experiment. Had the temperature outside been a little hotter, and hence the deck a little warmer, it could have cooked more thoroughly. The temperature of a safely cooked egg is about 160°. Check out the video below to see the end result:
Today felt so hot because the dew point was near or at 80° for a good portion of the afternoon. That's a rare occurrence and signals the presence of an intense amount of moisture in the air. Humid is an adjective that doesn't even describe how it felt. Tomorrow should be almost as hot with the high topping out near 93 and heat indices near 110. This has prompted the National Weather Service to issue another Heat Advisory from 1pm to 8pm tomorrow. A "cold" front accompanied by a little southward dip in the jet stream (a trough) will increase scattered thunderstorm chances tomorrow afternoon in Louisville. The Storm Prediction Center places us under a Slight Risk for severe weather, mainly due to the threat for some hail and strong winds. The chance for storms could continue into Wednesday morning as the front passes through, but the lack of surface heating should suppress most of the development. We should dry out for the rest of the week with highs near 90. Stay cool out there!
Now to the egg frying part. I didn't want to fry an egg on the surface of the wooden deck because it may stain it. So, I put a metal cookie sheet right on top of the deck surface. This not only protects the deck, but easily heats up in the direct sunlight. After a few minutes in the sun, the temperature of the cookie sheet with non-stick spray applied about equaled the temperature of the deck surface.
Since the refrigerator at my house was void of eggs, I poured out the one-egg equivalent of egg beaters, the made-from-eggs substitute that you find at the grocery store, into a measuring cup. This may have thrown my results a bit, but hey, this is supposed to be fun right? Once the cup of egg beaters warmed to the ambient air temperature (around 96°), I poured it out on to the cookie sheet.
The results were interesting. I spread the liquid eggs around on the pan to resemble a flat pancake or crepe to increase surface area for heating. After a few minutes the edges of this "pancake" turned crispy and the middle became a thicker liquid with solid "chunks" (yeah, don't read this if you're getting ready to eat dinner) embedded in it. The surface of the deck was cooling down just before five o'clock, so this marked the end of the experiment. Had the temperature outside been a little hotter, and hence the deck a little warmer, it could have cooked more thoroughly. The temperature of a safely cooked egg is about 160°. Check out the video below to see the end result:

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Sunday, July 10, 2011
7/10 - 3:30pm - Heat Advisories and Warnings
The hottest days of summer are yet to come, with today and tomorrow being just the start. A ridge of high pressure has locked itself into the eastern half of the nation, and many are feeling its hot and humid effects. It's 91° at Louisville International Airport, 88° in the southeastern suburbs of Louisville, 91° in Bowling Green, KY, and 95° in Jackson, TN as of 3pm EDT/2pm CDT. Doesn't take me to tell you that those are some hot readings! Areas near the Louisville area have been placed under a Heat Advisory until 8pm tomorrow while areas to the west of Owensboro have been placed under a more strongly-worded Excessive Heat Warning. Highs in Louisville could reach near 96° tomorrow with heat indices ("feels like" temperatures) up to 110.
Most of West Tennessee is under an Excessive Heat Warning until tomorrow at 10pm. Jackson could get up to 100 tomorrow with Memphis easily passing into the triple digits. Heat indices near or above 110 are expected, so limit your time outside if possible and drink lots of water.
As a trough and associated "cool" front dip down from the north, we should see chances for storms enter the forecast by Tuesday, which will help to break the heat a bit. While more scattered in Tennessee, Kentucky will likely see a good helping of storms during Tuesday afternoon and evening, some of which may be strong. The Storm Prediction Center has placed portions of Kentucky (including the Louisville area) under a Slight Risk for severe storms. I don't think there will be much, if any, of a tornado and hail threat from these, but gusty winds could present some issues across the region.

As a trough and associated "cool" front dip down from the north, we should see chances for storms enter the forecast by Tuesday, which will help to break the heat a bit. While more scattered in Tennessee, Kentucky will likely see a good helping of storms during Tuesday afternoon and evening, some of which may be strong. The Storm Prediction Center has placed portions of Kentucky (including the Louisville area) under a Slight Risk for severe storms. I don't think there will be much, if any, of a tornado and hail threat from these, but gusty winds could present some issues across the region.
Monday, August 16, 2010
8/16 - 1:30pm - Hello From Mississippi State!
I'm all moved in and ready for another semester at Mississippi State University! While temperatures here this week are comparable to Louisville, the humidity is considerably higher and makes it challenging to do anything outside. For a comparison, the dew point in Louisville right now is 61 degrees while at MSU it's 72 degrees. The proximity of Mississippi to the Gulf of Mexico causes the higher humidity and those scattered afternoon tropical air-fueled thunderstorms that can put a lid on the heat for some areas.
Speaking of things tropical, the remnants of Tropical Depression Five off the coast of Louisiana may strengthen again (60% chance according to the National Hurricane Center) as it nears land and become a tropical depression once again. Regardless of whether this low strengthens again or not, it will bring quite a bit of rain into Mississippi by Wednesday and Thursday as it moves inland and curves eastward. This may put a slight damper on the heat around East Central Mississippi (lower 90's instead of upper), but temperatures will rise back into the upper 90's by the weekend with that daily chance of afternoon storms.
Speaking of things tropical, the remnants of Tropical Depression Five off the coast of Louisiana may strengthen again (60% chance according to the National Hurricane Center) as it nears land and become a tropical depression once again. Regardless of whether this low strengthens again or not, it will bring quite a bit of rain into Mississippi by Wednesday and Thursday as it moves inland and curves eastward. This may put a slight damper on the heat around East Central Mississippi (lower 90's instead of upper), but temperatures will rise back into the upper 90's by the weekend with that daily chance of afternoon storms.
Wednesday, August 11, 2010
8/11 - 11:45pm - One Hot Summer...

It's that time of year again. Like many college students, I'm heading off to school for the semester and that means not only a change of scenery for me, but a change of content on this blog for you readers out there. I'll be leaving Louisville for Mississippi State University on Sunday and I'm very excited to be getting back into the swing of things. This summer has felt extremely long for me and there's a good reason for that... Mississippi State has a three and a half month summer break, which is over a month more than the summer breaks I've had back home in Louisville. That extra month allowed me to witness eight tornadoes in the Plains this year while storm chasing. Needless to say, Mississippi State is a storm chaser-friendly university with that kind of semester schedule. As far as the content change on the blog goes, you'll be seeing Mississippi State-centric weather updates with a wealth of other weather news from around the nation. Hurricane season is still in full swing and I'll be covering that as well. As the semester gets underway I may throw a few surprises in the mix as well, so be sure to check back for new blog posts!
Sunday, July 25, 2010
7/25 - 12pm - More Heat and Scattered Storms

We may think the heat is bad here in Kentuckiana, but there's nothing like a warm July afternoon in Death Valley, California. Look at the forecast for that area today from the National Weather Service:
Today: Mostly sunny and hot, with a high near 121. Calm wind becoming south between 4 and 7 mph.
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Thursday, July 22, 2010
7/22 - 10pm - Could We Get Another Shot at 100 Degrees?
100 degrees might not be that far off as high pressure has settled into the eastern half of the country. As it draws up warm, moist air from the south over the next couple days, temperatures and heat index values will skyrocket. The National Weather Service in Louisville has issued a Heat Advisory from noon to 7pm for both tomorrow and Saturday in lieu of the heat and humidity. Temperatures both tomorrow and Saturday could get very close to 100 degrees and even hit it in areas influenced by the urban heat island effect (like downtown Louisville and the larger suburbs). As dew points get into the lower to mid 70's, heat index values will surge past 100 or even 105 over the next couple days. In other words, be careful and stay hydrated if you have to go outside anytime soon!
Relief will come in the form of a front on Sunday, which should bring us a chance for thunderstorms until Monday morning. Temperatures will stay in the lower 90's after that with a small daily chance of rain through the remainder of the workweek.
Tropical Storm Bonnie (formerly Tropical Depression Three) has formed off the coast of Florida and is expected to hit the South Florida Coast before heading out to the Gulf of Mexico. It should remain a tropical storm until it makes landfall somewhere near Louisiana according to both the
National Hurricane Center and the spaghetti chart (a compilation of various computer model forecast tracks - see right image). We'll have to keep a close eye on any intensification of this storm, especially when it exits the Florida Peninsula and heads into the Gulf.
Relief will come in the form of a front on Sunday, which should bring us a chance for thunderstorms until Monday morning. Temperatures will stay in the lower 90's after that with a small daily chance of rain through the remainder of the workweek.
Tropical Storm Bonnie (formerly Tropical Depression Three) has formed off the coast of Florida and is expected to hit the South Florida Coast before heading out to the Gulf of Mexico. It should remain a tropical storm until it makes landfall somewhere near Louisiana according to both the

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Thursday, July 15, 2010
7/16 - 12am - More Heat and Rain on the Way!

A cold front sitting just north of the Ohio River is firing off some strong storms just to our west and we'll likely see some rain from those tonight as they push south. This front will stall out in Southern Kentucky and generate more rain chances for us on Friday and Saturday before things taper off on Sunday. Another front will bring daily rain chances on Monday and Tuesday, but high pressure will regain control for the rest of the week and dry things out. Temperatures will remain consistently in the low to mid 90's throughout the next week.
Oil has finally stopped leaking from BP's Deepwater Horizon rig accident site after a new containment cap was placed on it this afternoon. This marks a possible end to the 85 days of leakage that has caused mass devastation along the Gulf Coast and called into question the regulatory practices in place for the industry. There's still no guarantee that the cap will hold and it will be a "wait and see" game for many in Gulf Coast region. To read an article on the leak stoppage, click here.
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