04/19/2017

Asteroid Passing Close to Earth Today!

A large asteroid (one the size of six football fields) is flying past the Earth today . . . at a safe distance of 1.1 million miles. That is about 4.6 times the distance from the Earth to the moon. Although it will not come close to colliding, it is considered a close encounter to Earth for an asteroid this size.

Video Credit: Nasa Jet Propulsion Lab

Radar images of asteroid 2014 JO25 were obtained in the early morning hours on Tuesday, with NASA's 70-meter (230-foot) antenna at the Goldstone Deep Space Communications Complex in California. The images reveal a peanut-shaped asteroid that rotates about once every five hours. The images have resolutions as fine as 25 feet (7.5 meters) per pixel.

Asteroid 2014 JO25 was discovered in May 2014 by astronomers at the Catalina Sky Survey near Tucson, Arizona -- a project of NASA's Near-Earth Objects Observations Program in collaboration with the University of Arizona.

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This composite of 30 images of asteroid 2014 JO25 was generated with radar data collected using NASA's Goldstone Solar System Radar in California's Mojave Desert

How and When to See it?

The asteroid will approach Earth from the direction of the sun and will become visible in the night sky after April 19. It is predicted to brighten to about magnitude 11, when it could be visible in small optical telescopes for one or two nights before it fades as the distance from Earth rapidly increases. This encounter is the closest an asteroid has come to Earth for at least the last 400 years and will be its closest approach for at least the next 500 years.

Is it a Rarity?

Small asteroids pass within this distance of Earth several times each week, but this upcoming close approach is the closest by any known asteroid of this size, or larger, since asteroid Toutatis, a 3.1-mile asteroid, which approached within about four lunar distances in September 2004. The next known encounter of an asteroid of comparable size will occur in 2027 when the half-mile-wide asteroid 1999 AN10 will fly by at one lunar distance, about 236,000 miles.

To learn more about this close pass of asteroid 2014 JO25 click here.

And for more information about asteroids and near Earth object can be found here.

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04/18/2017

The Four Types of Thunderstorms... and the Dangers they Pose!

On average, Kentuckiana recieves approximately 45 inches of precipitation per year and while some of that falls as sleet or snow, most of it comes in the form of rain.  

Of the rain that falls, most of it occurs during thunderstorms during the spring and summer months.

There are several types of thunderstorms, but each of them starts out the same.  As cumulus clouds! 

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These cumulus clouds grow as moisture laden parcels of air rise, expand and cool causing water vapor to condense into cloud droplets/ice crystals and then eventually into precipitation.  These areas of rising air are called "updrafts" and essentially are what feed the storm.  

Once precipitation begins to fall, it carries a doward momentum of air with it known as the "downdraft".  The harder the rain/hail, the stronger the downdraft.  The downdraft is what you feel when a storm blows in "rain cooled air".  

However, this downdraft mechanism is also what essentially kills the storm.  You see, in the case of the typical "summertime thunderstorm" the updraft that creates the thunderstorm eventually gets overtaken by the downdraft and it runs out of fuel.  

Ordinary

This is the basic life cycle of the thunderstorm and a typical storm will form and then fall apart within an hours time.  

Single Cell Thundertorm

When a thunderstorm updraft goes up and then straight back down, as illustrated in the diagram above, it is known as a SINGLE CELL thunderstorm..  Also known as "pop up" or "popcorn" storms, these are very common during the heating of the day during the late spring or summer months.

Towering-thunderstorm

The single cell thunderstorm can bring brief heavy rain, small hail, gusty winds and dangerous lightning.  They also have the ability to bring quick relief from intense summertime heat!

Multi Cell Thunderstorm

Often times, single cell storms will combine and interact with other single cell storms to form a MULTI CELL thunderstorm.   

Thunder storm types

Multi cell storms are also very common during the spring and summer months.  In addition to bringing the risk of gusty winds, small hail and lots of lightning, these storms are capable of dropping a tremendous amount of rain over a short period of time especially when they "train" or line up moving continuously over the same areas.  This can lead to flash flooding.

Fountain Square Apts in Highview  Photo credit Scott Utterback

Squall Line Thunderstorm

Another common, and often times dangerous, type of a thunderstorm is the SQUALL LINE. 

A squall line is a large line of intense thunderstorm activity that can stretch across hundreds of miles of real estate.  These storms are common here in Kentuckiana especially during the spring and summer months and although they are capable of producing very heavy rain, lightning, hail and even quick spin up tornadoes, their biggest threat usually comes in the form of wind!

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Squall lines often produce winds in excess of 60 mph and have been known to produce wind gusts to over 100 mph!  They can be more damaging than even strong tornadoes because of their size that the amount of area they can affect.

When they become particularly strong, they are called a "derecho" which means widespread wind storm in Spanish. 

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The squall line can be easily identified on radar as well as the cloud structure.  The above image features a rather large and ominous looking "shelf cloud" which forms just ahead of the squall line.  

The shelf cloud forms in the presence of high speed downdraft winds that race out ahead of the heavy precipitation.  

The Supercell Thunderstorm

The other main type of thunderstorm is the supercell.  Fortunately, the supercell is also the least common because it is potentially the most severe of all thunderstorms.  

Tornadic_supercell

The supercell is characterized by having a rotating updraft.  This rotating updraft allows the storm to live much longer than normal single cell or mutli-cell thunderstorms and it also allows it to become more organized.  

On radar, the supercell often looks like a kidney bean and sometimes can display a "hook echo" pattern which can be an indicator that a tornado could be occuring.

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Like the Henryville EF-4 from March 2012, almost all violent or strong tornadoes form from supercell thunderstorms.

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In addition to tornadoes, they are also capable of producing extremely large hail, destructive winds, extreme lightning and flash flooding.  

WDRB Meteorologist Jeremy Kappell

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SEVERE RISK? Rain & Storms Thursday, Then Again Saturday...

Aside from a few hit or miss storms today and tomorrow, our next solid rain chance moves in late Thursday. Now that we are well into spring storm season, it's always a good idea to inspect the data to see whether or not anything could be severe. The map below tells us how much instability and wind energy the storms have to work with as they roll through. According to the GFS, there's about 1,000 units of CAPE (Convective Available Potential Energy) in our area with 15-25 mph winds Thursday evening. We would refer to this as a high CAPE, low shear environment. Storms would briefly pulse up, then collapse. As they fall apart, you can get some gusty winds so we can't rule out a warning or two. The best chance for a stronger storm would end up in our northwest counties of Indiana. The rest of us just have to deal with downpours and lightning.

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Let's move on to Saturday afternoon. At this point, rain still appears to be a good bet, but we are still a few days out so the timing could change a little. Luckily, severe weather doesn't pose a threat. According to the GFS, there's virtually no CAPE in Louisville. This would make a soggy situation for Thunder Over Louisville with cool highs in the 50's. Down in southern Kentucky as you get closer to the Tennessee border, you can see about 200 units of CAPE with 50 - 60 mph winds. There may be a few strong storms down there in the high shear, low CAPE environment. Join Marc and I on WDRB tonight for more specific timing of rain chances during the air show and fireworks.  

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-Rick DeLuca

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04/17/2017

THUNDER FORECAST: Rain Likely. Heavy Storms Possible!

While still several days away, confidence is growing on a wet forecast for Saturday.  Of course this is not good news for Thunder Over Louisville and the kick off to the 2017 Kentucky Derby Festival.  

The Storm in Question

Gfs jet

The storm is currently located over the North Pacific revolving over top of some high speed jet stream winds that are just now beginning to come onshore the West Coast.

By Friday the core of these upper level winds are expected to eject out of the Rockies and into the Southern Plains helping to develop a surface low over West Texas.  From there, the low is forecasted to deepen as it travels towards northeast and eventually into Kentuckiana by late Saturday and Saturday night.  

Let's time it out with the current run of the Euro...

The 12z run of the Euro shows an area of low pressure approaching out of Northern Arkansas with a large shield of rain extending into the Lower Ohio Valley Saturday morning.

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Widespread rain continues locally with thunderstorms developing near the low across the Middle Mississippi River Valley early Saturday afternoon.

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The low deepens arriving near Evansville by early evening with very heavy rain/storms approaching our area.

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The low travels right over our area Saturday night as widespread rain and storms continue.

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By morning on Sunday the bulk of the rain shifts east into Appalachia with wrap around showers locally.

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If the Euro is correct, then it rains all day Saturday and Saturday night potentially falling heavily at times with lightning and thunder.  This would mean that both the air show and the firework display would be negatively impacted.  In fact, it's possible that parts, if not all, of the air show could be cancelled due to low cloud "ceilings".  

What do I think?  

Unfortunately, I think the Euro might have the right idea.  This is a pretty classic set up for us this time of the year with a deepening Southern Plains low traveling northeast along an existing frontal boundary.  This would give it the ability to pull up abundant moisture over top of a strong "baroclinic zone" or tight temperature gradient presumably located over our area.  The latest run of the GFS supports this solution with the potential for heavy rain and storms especially late in the day.  

Is severe weather possible? 

The short answer to that is yes, it's possible.  However, a more likely scenario keeps surface temps too cool, likely in the 60's, for much of a severe threat in Louisville.  However, this doesn't reduce the potential for very heavy rainfall and thunderstorms.  

So how much rain?  

Data from both the Euro and GFS suggest that we could see widespread 1 to 2 inch rainfall amounts Saturday.

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Moral of the story... while I wouldn't cancel your Thunder Plans at this range, I would start preparing for what could turn out to be a very wet Saturday.  

Marc and Rick have your update on WDRB News this evening.

WDRB Meteorologist Jeremy Kappell

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LYRID METEOR SHOWER 2017...

The annual Lyrid meteor shower has started! It’s active each year from about April 16 to 25, peaking early Saturday morning April 22nd. 

Overview:

This year's second major meteor shower – the Lyrids – will radiate through the Summer Triangle*. Patient observers will be rewarded with the sight of 18 meteors per hour before dawn from a dark sky location. Since the moon will be nearly to its new moon phase, extra light won't be an issue. The actual new moon is on April 26.

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When:

Peak Viewing: April 22 during the predawn hours 

Where:

Summer Triangle in the eastern sky

*The Summer Triangle is made of the three bright stars Deneb in Cygnus (the Swan), Altair in Aquila (the Eagle), and Vega in Lyra (the Lyre, or harp). Find Vega and Lyra high in the eastern sky a few hours after midnight this month.

Unfortunately, the clouds won't cooperate with us. Clouds may be thin enough in our eastern counties that you might be able to catch a handful of meteors, but skies do look mostly cloudy for now. We will keep you posted as we get closer to the weekend.

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Watch "What's Up for April 2017" below for more...

Video Credit: NASA Jet Propulsion Laboratory

 

-Rick DeLuca

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Thankful For Easter Gully Washers

From Jude Redfield...

    I completely understand that yesterday's rain made for a mess at times during our Easter fun. Without that rain our Monday pollen count wouldn't be able to benefit however. Those downpours were sweet relief to allergy sufferers. Enjoy today, because lower rain chances and smaller rain coverage the next couple of days has our pollen count surging to the high range.

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04/16/2017

The Storm Prediction Center Monitoring Severe Risk

The Storm Prediction Center has issued a Mesoscale Discussion on the potential for strong storms in our area late this afternoon/evening.  Here is there discussion...

Mcd0505

SUMMARY...Isolated strong to damaging winds and perhaps marginally severe hail may occur with thunderstorms across this region through the afternoon. Watch issuance is unlikely owing to an overall marginal severe weather threat.

DISCUSSION...Scattered to numerous thunderstorms are ongoing across this region as of 1855Z along a pre-frontal trough extending from northeast to southwest across the OH Valley, and with renewed development in southeastern MO/northeastern AR along part of a MCS that formed overnight across the southern/central Plains. The airmass across the Mesoscale Discussion area is weakly unstable per 18Z RAP Mesoanalysis (MLCAPE generally 500-1250 J/kg), and is forecast to remain so through the remainder of the afternoon owing to modest 700-500 mb lapse rates (around 6.0-6.5 C/km). Still, steepening low-level lapse rates with diurnal heating and generally 25-30 kt mid-level flow may promote some strong to damaging winds with the more robust updrafts. This localized damaging wind threat may be somewhat greater in association with the eastward moving cluster of thunderstorms approaching southern IL/western KY. In addition to the isolated wind threat, there may be a marginal hail threat with any thunderstorm that can remain mostly discrete along the pre-frontal trough, as weak effective bulk shear is forecast to remain somewhat supportive of updraft organization. Overall, the lack of both stronger instability and shear will likely limit the magnitude of the severe threat, and watch issuance is unlikely.

So what do I think?

Cutting through all the weather jargon, I agree that the threat for damaging winds or hail is low.  However, like we've already seen today, the National Weather Service might issue a warning or two with some of the strongest storms.   

In addition, I believe the bigger threat will come in the form of excessive rainfall for parts of the area and flash flooding will be possible as we see multiple rounds of heavy storms developing as we head into this evening.  

Here's a look at the latest run of the HRRR, hi-res computer model...

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I'll be sure to keep you posted through my social pages as the storms arrive.  Stay tuned and have a safe Easter everybody!  

WDRB Meteorologist Jeremy Kappell

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"Nowcasting" of Today's Storms and Discussing Potential Severe threat

Severe Risk:

The Storm Prediction Center has issued a "Marginal Risk" for severe weather for tomorrow. This is the second lowest of six categories and is defined as an area of severe storms of limited organization and longevity, or very low coverage and intensity. Scattered thunderstorms are expected to develop this afternoon and evening. Not much has changed with this graphic since yesterday. It is slightly smaller, but still includes most of our area. The main threats have not changed. It will be isolated, damaging gusty winds, small to marginally severe hail and heavy rain. 

Image 1

Set up:

There is a weak and slow moving cold front positioned out to our west and it will be moving toward our region over the next few hours. However, a northern portion of convection ahead of the main line and has moved into southern Indiana ahead of schedule and did not fall apart as many of the models suggested. Sigh.

HOWEVER. this could also lower our severe threat for this afternoon, because there is very limited recovery time between rounds one and two. 

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(*And in the hour in took for me save images, analyze current conditions and write this blog, more showers started to pop up across the area as well! Again, ahead of schedule. HRRR showed this, but developing later in the day. See below.) 

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This image of Towercam was saved at 9:39 am and we were seeing breaks in the clouds and some sunshine. 

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Basic gist I am getting at here: 

More clouds/rain = more stable atmosphere = less chance for severe weather 

More sun = more UNstable atmosphere = better chance for severe weather 

Ingredients:

As of this morning, models are showing CAPE or Convective Available Potential Energy, a measurement of instability, around 1500 J/kg during the afternoon. Which is certainly enough for strong to severe storms to develop...

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HOWEVER, The current CAPE values are less than impressive, probably due to the current showers around the region. Checking SPC's Mesoanalysis Page, the current Mean level CAPE (CAPE calculated using a parcel consisting of Mean Layer values of temperature and moisture from the lowest 100 mb above ground level) is only around 100 J/kg. Which is very low. It will need to increase a lot over the next few hours in order to develop severe weather. 

Image 8

All along, our wind energy has been lacking. Below is an image of the mid level winds showing around about 25 kts. Sufficient for strong to severe storms, but not impressive.  The lack of wind energy will keep this from being a widespread severe weather event, but we cannot rule out a rogue severe storm or two with this wind shear.  

Image 8

Timing: 

As I mentioned above, we are already seeing showers and storms, which the computer models did not handle well at all. Even as I write this, the HRRR is not picking up the changes, but has been trying initializing better over the last hour. Compare and contrast this first image of AT to the first radar image. It is failing to bring the showers into our northern counties at the right time, so we have to take that into account with the images moving forward. 

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2:30 on AT looks more like 11:30 on the radar, but the main idea is that we will continue to see more development of showers and storms throughout the afternoon and evening ahead of the front. 

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The front will push through this evening with the line of showers and storms moving through. Coverage will be more widespread during the late afternoon and evening. 

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And precipitation will quiet down briefly after the front passes through. 

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We are not expecting a ton of rain. Roughly a quarter of an inch to a half an inch. However, with some of these cells that have heavy rain embedded within, they could drop a lot more, up to an inch locally. 

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So what do I think?? 

Instability needs to do a lot of work in order to develop any severe weather, but the threat is not off the table for today. Because it is a holiday and people are out and about, I do not want to diminish the potential. We could still see a few warnings across the area, but it is looking less likely because of the showers developing earlier and we didn't have enough recovery time between rounds 1 and 2. With that said, we could see stronger to severe storms in the areas that stay dry longer. I am keeping a close eye on the conditions and will update this blog as needed! 

We do not dry up on Monday. There are still showers and storms in the forecast.  In fact, there is a very unsettled weather pattern for next week, with above average temperatures. Be sure to join Jeremy this evening on WDRB News to hear about that! If and when storm become severe, we will be keeping you informed in a variety of ways. One of those is on social media. The links to my pages are below! 

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-Katie McGraw 

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04/15/2017

A Stormy Easter Expected. Strong Storms and Excessive Rain Possible!

The combination of a slow moving cold front, heating and abundant low level moisture will result in multiple rounds of heavy rain and storms for Easter Sunday.

Satrad

Some storms could be strong and in some cases the rainfall could be excessive.

Let's time it out with AdvanceTrak...

AT shows a batch of showers developing during the predawn hours on Sunday.

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This activity could linger to around sunrise. 

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A break in the activity is possible during the mid to late morning hours.

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We'll be tracking the development of a line storms into the early afternoon hours.

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This line of potentially strong storms pushes south into our southern counties by late afternoon.

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Following another possible break in activity, another round of heavy storms develops during the evening.

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The rain could linger well into Sunday night.  

What do I think?

While a few strong storms will be possible, wide spread severe weather is not anticipated.  However, any of the storms that get going during the afternoon/evening will be capable of some gusty winds, frequent lightning and very heavy rainfall.  Locally, the rain could be excessive.

So how much rain?  

Rainfall projection

Locally, better than two inches will be possible for some where storms are able to "train" over the same areas.  If this occurs, then flash flooding could become a concern.  

Stay tuned. Have a safe and blessed Easter everyone!

WDRB Meteorologist Jeremy Kappell

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Easter Storms: Severe Threat Posted, Timing and Threats

Severe Risk:

The Storm Prediction Center has issued a "Marginal Risk" for severe weather for tomorrow. This is the second lowest of six categories and is defined as an area of severe storms of limited organization and longevity, or very low coverage and intensity. Scattered thunderstorms are expected to develop on Sunday during the afternoon and evening. The main threats will be isolated, damaging gusty winds, small to marginally severe hail and heavy rain. There is also some uncertainty regarding the strength of the storms, particularly west, because of the chance for showers early in the day and residuals clouds during the afternoon. 

Image 1

Set up:

There is a weak cold front out to our west and it will be moving toward our region over the next day. We are currently in the warm sector and I'm sure you have noticed! Today we will be warm and breezy, tomorrow the rain chances spike to about a 70% chance. However, let's be clear, it does not mean there will be a wash out. There will still be some dry time and not everyone is guaranteed to see rain or severe weather. 

Image 2

Ingredients:

As of this morning, models are showing CAPE or Convective Available Potential Energy, a measurement of instability, around 1000-1500 during the afternoon J/kg. Which is certainly enough for strong to severe storms to develop, especially because the timing of the storms seems to coincide with peak heating of the afternoon and an unstable atmosphere. 

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However, our wind energy is lacking. Below is an image of the mid level winds showing around 20 kts only and it is unidirectional as you move up the atmosphere.  The lack of wind energy will keep this from being a widespread severe weather event, but we cannot rule out a rogue severe storm or two.    

Image 8

Timing: 

Clouds will increase this evening and overnight and there is a chance to see a few showers during the morning. There is likely to be a lull in the activity which would give a chance for the atmosphere to destabilize and help the development of strong to severe storms later in the day. 

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Showers and storms will redevelop during the afternoon and evening. This is going to be our best chance for strong to severe storms. With the Advancetrak graphics, I wouldn't take them as gospel but rather a gauge as a way to plan your holiday. And remember there will be times will dry weather as well! 

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But we want you to plan accordingly for storms on Easter and know that they will be around on and off throughout the day. Notice there is still a chance during the later part of the day and into the evening as well, but the severe threat will start to diminish with time. We are not expecting a ton of rain. Roughly a quarter of an inch. However, with some of these cells that have some heavy rain embedded within, they could drop a lot more, up to an inch. 

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The front will stall and meander around the area on Monday and keep showers and storms in the forecast. 

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In fact, there is a very unsettled weather pattern for next week, with above average temperatures. Be sure to join Jeremy this evening on WDRB News to hear about that and the latest on the severe weather threat for tomorrow. I will also have more information bright and early tomorrow morning. If and when storm become severe, we will be keeping you informed in a variety of ways. One of those is on social media. The links to my pages are below! 

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-Katie McGraw 

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