Experimental model predicts the effect of the 2017 eclipse on weather

On a typical clear August day in the Great Plains, maximum downward shortwave radiation from the sun occurs about noon.

But if the sun is blocked partially for a few hours and completely for a few minutes, how will this affect temperature near the surface? Or to low-level winds? What impact will this drop in radiation have on existing weather, such as thunderstorms in progress?

Current operational weather forecasting models are not equipped to represent the eclipse and its effect on the weather.

Researchers at the NOAA Global Systems Division (GSD) and the Cooperative Institute for Research in Environmental Sciences (CIRES) have adapted an eclipse algorithm to use with their experimental version of the 3-km High-Resolution Rapid Refresh (HRRR) model. The algorithm, developed by a University of Barcelona team and shared by NCAR with the Weather Research and Forecasting community model, computes the degree of obscuration of the solar disk at each model grid point.

Based on this calculation, the model modifies the incoming solar radiation, which impacts the heating of the earth and, subsequently, the weather.

Image 1

Researchers at GSD and CIRES implemented and tested this algorithm within the HRRR model. They used meteorological conditions from 4 August 2017 but paired those with the anticipated astronomical information from 21 August when the eclipse will occur.

The researchers found that the eclipse will primarily affect temperatures: the model predicts a reduction in near-surface temperatures—from 1-4 C cooler in the penumbra region (widespread area over the U.S. that experiences a partial eclipse) to 3-7 C (5-12 degrees F) cooler along the path of the full eclipse maximizing near 1800-1900 UTC (2-3pm Eastern Time Zone).

The model also predicts that incoming solar radiation will be reduced by up to 900 W/m2 during the eclipse (see figure below), but the exact local effect will depend on the local cloud conditions next Monday. NOAA/GSD’s experimental version of the HRRR model (HRRRx) has now been modified to account for the eclipse in its real-time forecasts.

Learn more about the results from GSD's experiments of the likley effect of the eclipse on August 21.

Image 2

You can test the HRRRx experimental forecasts, now available and before and during the actual eclipse itself—including the effects of the eclipse starting Saturday night looking ahead 48 hours! Just click here.

Selected weather fields available, include downward solar radiation and cloud fields and 2-meter temperature, for HRRRx (with eclipse effect), HRRR-NCEP (without eclipse effects and some other differences) and HRRRx - HRRR-NCEP difference fields. NOAA’s National Weather Service runs the HRRR-NCEP model for operational usage.

The eclipse and state-of-the-art weather models like the HRRR offer a rare opportunity to compare conditions of the atmosphere with and without the eclipse, and see how it interrupts processes in the atmospheric boundary layer from coast-to-coast.

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-Katie McGraw 



  • NOAA/ESRL/GSD/CIRES Joe Olson, Michael Toy, and Jaymes Kenyon
  • NCAR/MMM - Wei Wang, Jimy Dudhia, Dave Gill Alex Montornes, U. of Barcelona

Eclipse Info You Need To Know

From Jude Redfield...

    In Louisville the amount of sun covered up by the moon will be near 96% around 2:27pm Monday. During this time the temp may drop a few degrees.


    The eclipse begins around 1pm and will wrap up around 3:50pm. In Louisville we'll get a little more than 2 minutes worth of near darkness starting around 2:27pm.


    All experts agree the only thing that will assure you of no harm while viewing the eclipse are the NASA approved safety glasses. Make sure you research the type of glasses you have before viewing the eclipse.

    Please check out the map below to find out the amount of sun covered up during peak viewing in your area.

WHite brick

    Finally the forecast for Monday! I do expect a scattering of typical, summer (fair weather) clouds. Nothing I see at this points leads me to believe overcast skies will take hold. Unless a last minute curveball is thrown we are in for a serious treat. The heat will be a factor as temps make the low 90s so have the bottled water handy. Make sure to check in with Katie and Jeremy this weekend for the most up to date cloud forecast. -Jude Redfield-




Timing Today's Storms

The Storm Prediction Center has posted a "slight risk" for severe weather for our northern most counties for today. The rest of the region is under a "marginal risk". 

A marginal risk of severe weather is an area of severe storms of either limited organization and longevity, or very low coverage and marginal intensity.

The potential threats will be heavy rain, gusty damaging winds and brief small hail.  

The better chance for severe weather is to our NW. 

Image 1

Showers and storms are moving through right now through southern Indiana and are pushing NE at around 40-45 mph. So far, they have only been strong. This is really looking like the main event. A few showers and storms may linger a bit into this evening and then eventually taper off tonight. 
Image 3

These are all associated with a cold front, as the cold front pushes through, high pressure will briefly take over on Friday and we will bring back the sun! 

Image 3

You can see temperatures are cooler out to our west following the front. We are currently (just after 2 pm) sitting in the low 90s, but it feels like 99 degrees, just shy of triple digits downtown. Tomorrow, it will be slightly cooler, with highs in the mid to upper 80s. 

Image 5

But what you will notice more, is a drop in the humidity. Dew points today are STICKY! In the mid 70s. Tomorrow they will drop by about 10 degrees and this will make it feel more comfortable. 

Image 3


The HRRR is initializing quite well and looks almost identical to our radar. The first line will push through but we could still see a few showers and storms this evening as well. 

Scroll through the images of Advancetrak to get an idea of coverage and timing for the rest of today. 
AT 5

Notice we could still see a few linger storms following this first line into this evening. 

AT 5
AT 5

And coverage will become less and less with time. 

AT 5

Everything will taper off by the overnight. 
AT 5

If and when storms go severe, we will be the first to let you know! This is especially true on social media. Be sure to like our Facebook pages or follow us on Twitter. The links to my pages are below.

Are there anymore storm chances for the weekend?  What about the eclipse day? Get a glimpse of the eclipse forecast tonight on WDRB News with Marc and Rick!

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-Katie McGraw 




Watch Could be Issued

The Storm Prediction Center is monitoring the conditions for our area for severe weather for today. The best chance for severe weather is in our northern counties, in southern Indiana. The main threats are going to be gusty, damaging winds, hail, frequent lightning, locally heavy rain. Isolated tornadoes are possible as well. Read what SPC has to say about the threat below and be sure to stay weather aware.

 Image 1

Concerning...Severe potential...Watch possible

Valid 171604Z - 171800Z

Probability of Watch Issuance...60 percent

SUMMARY...Line of storms across eastern IN will gradually strengthen
as it continues eastward in OH. Damaging wind gusts and perhaps a
tornado or two are possible within the strongest storms. Trends will
be monitored for watch issuance.

DISCUSSION...Recent regional radar imagery has shown a gradual
increase in storm intensity within the line of thunderstorm
stretching across eastern IN. Moisture advection ahead of the line
is supporting downstream airmass destabilization and mesoanalysis
now estimates MLCAPE over 1000 J/kg for much of the region. General
expectation is for the ongoing line to gradually intensify as it
interacts with the very moist and unstable airmass downstream.
Strengthening mid-level flow will also contribute to stronger shear
and a more supportive environment for better updraft organization.

Predominately linear mode and the very moist airmass will support a
primary severe threat of damaging wind gusts associated with wet
microbursts. Additionally, the strengthening mid-level flow will
contribute to a modest increase in storm-relative helicity. This
increased helicity and low LCLs support the potential for a few

Stay tuned for the latest information.  Marc, Rick and I will be here and keeping you informed for the rest of today. Be sure to watch the news this evening with Marc and Rick on WDRB for the latest information. If and when storms go severe, we will be updating all of our social media pages, and cut into programming if necessary. The links to my social media pages are below. 

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-Katie McGraw 






ECLIPSE 101: Four Types of Eclipses...

Eclipses, whether solar or lunar, occur because of the periodic alignments of the sun, Earth, and moon. These three bodies, orbit in space in very predictable paths (yes, the sun orbits too. It orbits the galaxy once every 200 million years!). Ever since the days of Kepler and Newton, we have been able to predict the motion of planetary bodies with great precision.

There are Four Types of Eclipses

Depending on your location and on the specific geometry of the sun-Earth-moon system, you may experience one of four types of solar eclipses; total, partial, annular and hybrid.

A TOTAL ECLIPSE happens when the moon completely covers the sun. Here, the observer is standing under the umbral shadow of the moon. In a total solar eclipse, the sun’s outer atmosphere can be seen.


This image shows the Aug. 1, 2008, solar eclipse at the point of totality, when the moon completely blocks out the body of the sun, revealing the normally hidden, halo-like corona. Image Credit: The Exploratorium

The brighter stars and the planets come out. Animals change their behavior. Birds and squirrels nest. Cows return to the barn. Crickets chirp. There is a noticeable drop in both light level and air temperature. It is an eerie feeling. Totality can last for no more than about seven and a half minutes but is usually less than three minutes long.

A PARTIAL ECLIPSE occurs when the moon passes in front of the sun, off center and only a portion of the sun’s disk is obscured. Here, the observer is standing in the penumbral shadow of the moon.


Partial solar eclipse. Image Credit: Lou Mayo

AN ANNULAR ECLIPSE occurs when the moon passes dead center in front of the sun but, because the moon’s orbit is elliptical and so is sometimes closer and sometimes further from Earth, it appears too small to fully cover the disk of the sun.


Image of an annular solar eclipse as seen from the Japanese Hinode Satellite. Image Credit: Hinode/XRT

Here, a bright ring called the “ring of fire” appears around the dark disk of the moon. In an annular eclipse, the moon’s umbral shadow comes to focus – to a point – above the Earth’s surface.

A HYBRID ECLIPSE is a combination of total and annular eclipses. The eclipse begins as one type and ends as another.



-Rick DeLuca




NEXT 2 DAYS: Storms Are Possible & Some Could Be Strong...

August is back! The heat and humidity will fuel storms over the next two days. While many of you may be praying for rain, the storms that fire on Wednesday look very hit or miss in nature. A decaying batch of showers move in from the southwest during the morning. Then as we get into the early afternoon, storms begin to fire with downpours and lightning...


Even though we have a decent amount of CAPE(Convective Available Potential Energy), the wind energy on Wednesday doesn't really support severe weather. 


Thursday is a different story because we have more instability and wind energy. While neither one suggests a crazy outbreak of severe weather, storms could be strong to severe.  


A weakening line of storms move along and north of the river early in the day...


As the day wears on, storms boil up with the potential for gusty winds and hail...


A final round of rain arrives as a cold front sweeps in Thursday night...


Here's the bottom line...you may have to dodge a few storms around midday tomorrow, but I highly doubt they would be severe and many will miss out on the rain. On Thursday, multiple waves of scattered storms hit from time to time. If you happen to get them during the afternoon and evening, they could be strong to severe. If any warnings are issued, we will be the first to let you know. Join Marc Weinberg and I on WDRB for a full update at 10 and 11! 




-Rick DeLuca




TOTAL SOLAR ECLIPSE: Who? What? Where? When? & How?

On Monday, August 21, 2017, all of North America will be treated to an eclipse of the sun. Anyone within the path of totality can see one of nature’s most awe-inspiring sights - a total solar eclipse. This path, where the moon will completely cover the sun and the sun's tenuous atmosphere - the corona - can be seen, will stretch from Lincoln Beach, Oregon to Charleston, South Carolina. Observers outside this path will still see a partial solar eclipse where the moon covers part of the sun's disk.


Image Credit: Rick Fienberg, TravelQuest International and Wilderness Travel
Figure 1- In this series of still from 2013, the eclipse sequence runs from right to left. The center image shows totality; on either side are the 2nd contact (right) and 3rd contact (left diamond rings that mark the beginning and end of totality respectively). 

Who Can See It?

Lots of people! Everyone in the contiguous United States, in fact, everyone in North America plus parts of South America, Africa, and Europe will see at least a partial solar eclipse, while the thin path of totality will pass through portions of 14 states.  


Image Credit: NASA’s Scientific Visualization Studio
Figure 2- This map shows the globe view of  the path of totality for the August 21, 2017 total solar eclipse. 

What is It?

This celestial event is a solar eclipse in which the moon passes between the sun and Earth and blocks all or part of the sun for up to about three hours, from beginning to end, as viewed from a given location.  For this eclipse, the longest period when the moon completely blocks the sun from any given location along the path will be about two minutes and 40 seconds.  The last time the contiguous U.S. saw a total eclipse was in 1979.


Figure 3 – Diagram showing the Earth-sun-moon geometry of a total solar eclipse. Not to scale: If drawn to scale, the Moon would be 30 Earth diameters away. The sun would be 400 times that distance. Credit: NASA

Where Can You See It?

You can see a partial eclipse, where the moon covers only a part of the sun, anywhere in North America (see “Who can see it?”). To see a total eclipse, where the moon fully covers the sun for a short few minutes, you must be in the path of totality. The path of totality is a relatively thin ribbon, around 70 miles wide, that will cross the U.S. from West to East.  The first point of contact will be at Lincoln Beach, Oregon at 9:05 a.m. PDT. Totality begins there at 10:16 a.m. PDT.  Over the next hour and a half, it will cross through Oregon, Idaho, Wyoming, Montana, Nebraska, Iowa, Kansas, Missouri, Illinois, Kentucky, Tennessee, Georgia, and North and South Carolina.  The total eclipse will end near Charleston, South Carolina at 2:48 p.m. EDT.  From there the lunar shadow leaves the United States at 4:09 EDT.  Its longest duration will be near Carbondale, Illinois, where the sun will be completely covered for two minutes and 40 seconds.


Figure 4 - A map of the United States showing the path of totality for the August 21, 2017 total solar eclipse. Credit: NASA

When Can You See It?

Times for partial and total phases of the eclipse vary depending on your location. This interactive eclipse map(link is external) will show you times for the partial and total eclipse anywhere in the world.

Table 1

Table 1 – Example of eclipse times for cities in the path of totality. Credit: NASA


-- Kentucky:

Leitchfield, KY - 98.8%
Munfordville, KY - 98.9%
Greensburg, KY - 98.4%
Columbia, KY - 98.7%
Lebanon, KY - 97.2%
Springfield, KY - 96.8%
Bardstown, KY - 96.8%
Hodgenville, KY - 97.8%
E-town, KY - 97.5%
Hardinsburg, KY - 98.2%
Brandenburg, KY - 97.1%
Shepherdsville, KY - 96.5%
Louisville, KY - 95.8%
Taylorsville, KY - 95.9%
Shelbyville, KY - 95.2%
Eminence, KY - 94.6%
Bedford, KY - 94.1%
Carrollton, KY - 93.6%

-- Indiana:

Tell City, IN - 98.1%
English, IN - 96.5%
Corydon, IN - 96.4%
New Albany, IN - 95.7%
Charlestown, IN - 95.0%
Madison, IN - 93.6%
Scottsburg, IN - 94.4%
Salem, IN - 95.1%
Paoli, IN - 95.8%
Jasper, IN - 96.9%
Bedford, IN - 94.8%
Seymour, IN - 93.8%
North Vernon, IN - 93.2%

How Can You See It?

You never want to look directly at the sun without appropriate protection except during totality. It could severely hurt your eyes.  However, there are ways to safely view an eclipse of the sun and WDRB has you covered. You can get the glasses at Heine Brothers' while supplies last or join us at the Kentucky State Fair Thursday - Monday in the North Wing Lobby...



Credit: NASA

Curious about the weather for Monday, August 21st? Join Marc and I on WDRB for the latest on cloud cover and rain chances for the big day!




-Rick DeLuca




Rain for Many in the Morning!

Following a terrific weekend, it's looking like those rain chances come back quickly to start the new workweek.


A mid-level disturbance will combine with moisture returning from the south to produce a good shot at some shower activity during the morning hours tomorrow. 

Let's time it out with AdvanceTrak...







AT shows rain arriving around daybreak and exiting during the early afternoon hours.  

Best chance of rain rain will be along the Ohio and points to the south.  

Rain chances

Jude has a full update first thing on WDRB in the Morning.

WDRB Meteorologist Jeremy Kappell

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ECLIPSE OUTLOOK: Targeting those Rain Chances for the Big Day!

It's early, but perhaps not too early to start talking about that forecast for the August 21st eclipse.  

While it is entirely too early to talk specifics, it's not too early to start talking about chances for rain. 


Turning to the Euro's 50-member ensemble forecast model, we can start to get a picture of what to expect for the 21st.  Today's run showing an upper "trough" located over the Great Lakes with a strong upper "ridge" over the South Central US.

Timing and tracks of these upper features will be critical in determining how the weather will pan out for us that day, but the current ensemble data suggests only about a 10 or 20% chance for rain during the 24 hour period ending at 8 pm on the 21st.  


That's pretty encouraging.  While the lower resolution, 16 member GFS ensemble is not quite as optimistic, it's only showing between a 20 and 30% for us during the same time frame.


Keep fingers crossed that this holds!  I'll have a full update on the Eclipse Forecast tomorrow evening.  

Stay tuned!

WDRB Meteorologist Jeremy Kappell

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DUST DEVIL IN FRANCE: Watch How High Beach Items Were Thrown...

Yesterday in Antibes, France, a dust devil sent beach toys, umbrellas and more flying through the air. A dust devil is a strong, well-formed, and relatively long-lived whirlwind, ranging from small (half a meter wide and a few meters tall) to large (more than 10 meters wide and more than 1000 meters tall). They are usually harmless, but can on rare occasions grow large enough to pose a threat to both people and property.

Video Credit: Love Life World Travel

They are comparable to tornadoes in that both are a weather phenomenon of a vertically oriented rotating column of air, but that's where it ends. Tornadoes are associated with a larger parent circulation, the mesocyclone on the back of a supercell thunderstorm. Dust devils form as a swirling updraft under sunny conditions during fair weather, rarely coming close to the intensity of a tornado.


-Rick DeLuca