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58 posts from September 2016


When the Twirling Low Dances Out of Here

A large upper level low dropped into Kentuckiana yesterday and it has been sitting, churning and twirling over our area today.

9-30 the low

I have been mesmerized by the radar and the satellites the past few days. I could watch them all day. To see this water vapor satellite image below in motion click this link. 


As the spins, right on top of us, it continues to douse our region with periodic rain. But it is on and off. On and off. Spinning around us.  In the past day, (since 12 am) metro Louisville has seen roughly .30'' to .60'' of rain. That is about the same amount we saw on Wednesday, but more rain than we saw yesterday (Thursday). This low will help reverse the drought conditions of last week. Catch up on that topic here. 

9-30 rainfall today

Notice in the image below, not the entire region has seen as much rainfall as metro. Some areas have missed out completely and other parts have only seen a tenth of an inch. 

9-30 other rates

Those of us that have missed out on the bulk of the rain, still have the chance to see more! And those of us that are sick of the rain, won't have to deal with it for much longer! 

Let's track out this low! Tonight there will still be a few spotty showers and the low is to the SW of metro. 

9-30 at 10 pm

Scattered showers will continue tomorrow, but the low is starting to slowly shift north out of our region. 

9-30 at  11 am

By the late afternoon and evening, the low has finally cleared our area. However, the showers are not over quite yet! They will continue sporadically through the rest of your Saturday plans. They will be hit or miss though. So just have the umbrella with you and dress warm! Temps will still only be in the upper 60s. 

9-30 at  5 pm

By Sunday, the low has danced out of here, but we can't rule out a few more isolated showers. 

9-30 at sun 130 pm

So when do we FINALLY dry up?? Find out by tuning into WDRB News tonight with Marc and tomorrow morning with yours truly! I'll be on air bright and early from 6-9 am! Hope to see you then! You can also find me on social media with the links below: 

Katie McGraw's Facebook Page

 -Meteorologist Katie McGraw


Drought Conditions for Some

Do you have a case of brown lawn? If so - I am not surprised! The United States Drought Monitor was issued today and a portion of our area is under the "abnormally dry" category after a very dry September. 

9-29 ab dry

However, you may be wondering how this is possible after the recent rain and gloomy days. While the drought monitor was issued today, the period ended on Tuesday of this week. That was before the rain yesterday and today. On Tuesday, we had only seen 1.08'' of rain for the month. That was 1.64'' below the average for September.

However, thanks to a large upper level low, that has been churning over our region for the past two days, we have seen the return of some wet weather. It will continue to impact us for tomorrow as well.

9-29 surf map

Yesterday, we saw .63'' of rain in downtown. Some other locations have not seen as much rain and others have stayed completely dry. I picked some estimate locations on the graphic below for the past 24 hours. We have seen another .13'' of rain so far today downtown. There is more rain in the forecast for this evening, tomorrow and Saturday as well. 

But the question is-- will there be enough rain to revert the abnormally dry conditions? 

9-29 whole area est.

There will be more scattered showers, on and off, for the next two days and will be coming to an end on Sunday. By that morning, we expect to see roughly an inch of rain across the area. Although this isn't a TON of rain, it is long duration rain and creates sub soil moisture because it is actually permeating the soil and is not just running off into the gutter. If you touch the ground it will feel wet and this is good for drought! 

9-29 gfs rain

9-29 euro rain

9-29 nam rain

However, the 6-10 day outlooks from the Climate Prediction Center were issued yesterday as well. They show there is high probability for below normal precipitation to occur in our region over the next week. Once the cut off low finally gets out of here by the end of the weekend. 

9-29 cpc precp

But there is one more thing to consider and that is newly formed Hurricane Matthew in the Atlantic. We will have to continue to monitor Matthew and how it could impact our extended forecast as it moves north along the east coast. It could really alter that CPC outlook. 

Be sure to tune into WDRB News this evening with Marc and Rick to hear their analysis of the conditions and when we will see some warmer air! 

I'll see you tomorrow on WDRB News at 11:30 and 12! Until then you can find me on social media with the links below. Have a good day! 

Katie McGraw's Facebook Page

 -Meteorologist Katie McGraw

When Does The Climate Record Say You Can Expect The Season's First Snow?

So … it’s about that time of year, and for some of you, it’s already happened. Winter’s first snow. For those who are still waiting, here’s a handy historical map that ballparks the first day of snow for an average year. It’s based on the "normals" dataset constructed here at the National Centers for Environmental Information—the same dataset from which the familiar “Today’s normal high is ____” bit of your weathercast is drawn.

Before we dive into interpretation, a few caveats: this map isn’t the average date of the first observed snowfall. Technically, it’s the date by which there’s a 50% chance at least 0.1” of snow will have accumulated. It’s based on historical patterns from 1981-2010, with some “smoothing” to account for statistical noise in the data.


Colored dots indicate the date by which there’s a 50% chance at least 0.1” of snow will have accumulated, based on each location’s snowfall history from 1981-2010. Image Courtesy: NOAA 

By taking a closer look at the map, you can see Indiana favors October 1 - 31 while Kentucky leans more toward November 1 - 30.  Image Courtesy: NOAA 


A quick look at the map reveals the obvious: the main factors that govern the average day of your first snow are the same main factors that govern your other major climate characteristics: latitude and altitude. In general, the farther north you are, and the farther up you are, the earlier the threat of first snow. In fact, the highest elevation stations along the spines of the Rockies have a year-round threat of snow. On the other end of the spectrum, the Deep South, Gulf Coast, Desert Southwest and Hawaii have many stations that get snow so infrequently, there’s no date listed (empty circles). In these places, there just aren’t enough events to make robust statistics.

There are also a few interesting, but more subtle, regional features. Across the Plains and Midwest, instead of a straight-up east-west pattern, there’s a slight northeastward tilt, where earlier dates plunge farther southward in the plains, relative to the more Midwestern states. It’s especially noticeable along a line stretching roughly from the Texas panhandle to Chicago. This has a little bit to do with elevation, but more to do with the fact that the coldest air associated with many winter storms—including early winter storms—often barrel down the high plains, corralled by the Rockies to the west.

You may also notice subtle plumes of earlier dates peeking south from the Great Lakes. If you grew up near their southern shores, you know the drill: the first very cold, northerly winds of autumn can pick up a lot of moisture from the still-relatively-warm lakes. This often results in a rather rude, and rather early, annual introduction to winter precipitation. It’s already happened this year in parts of Michigan and upstate New York.

As you might expect, the first date of snowfall isn’t a constant thing. It varies naturally, like many other climate variables. That’s why we call them “variables,” right?

For example, take a look at Dodge City, Kansas. The dots on this graphic show the first date with one-tenth* of an inch or more snow for each cold season from 1950/51 (top) through 2014/15 (bottom).


The dots span from mid-September at the earliest to early January at the latest. That’s a three-and-a-half-month spread! Don't forget, this is solely based on climate data and is by no means a FORECAST. Hang in there snow lovers!



Weather Blog: Spin Cycle Keeps Churning

From Jude Redfield...

    Our morning radar as of 9:43am essentially shows what we are expecting the next few days. These showers will obviously dance around and be in different spots, but at any given point through Saturday these showers will be possible from time to time.


 Brief, chilly downpours are likely along with some small hail in the more intense showers.  SOMETHING TO NOTE...Underneath these cold core upper level low pressure centers comes the chance for cold air funnels in this kind of atmospheric set up.  Yesterday a few were reported around Indianapolis. For the next 48 hours the pattern would support the outside chance at seeing a couple cold air funnels across portions of Kentuckiana.  These typically cause NO problems. Such strong swirl aloft is noted and it doesn't take much for a tiny funnel to form way up in the clouds.


    Plenty of dry time will occur during this pattern as well. If everything goes according to plan THURSDAY NIGHT FOOTBALL GAMES will be dry. Now how often does everything go according to plan? LOL  Tonight's game time rain chance is about 30% -40%.


    Friday's rain chance is slightly higher than today. I'm going with a 60% chance on Friday before dropping it back to 40% on Saturday. If you are headed to the St. James Court Art Show on Saturday dress for temps in the 60s most of the day.


    Sunshine gradually overcomes the clouds Sunday into Monday. High temps in the low 80s come back by next Tuesday and Wednesday. -Jude Redfield-


Astronomical Vs Meteorological Fall

You may have noticed that meteorologists and climatologists define seasons differently from “regular” or astronomical spring, summer, fall, and winter. So, why do meteorological and astronomical seasons begin and end at different times? In short, it’s because the astronomical seasons are based on the position of Earth in relation to the sun, whereas the meteorological seasons are based on the annual temperature cycle.

People have used observable periodic natural phenomena to mark time for thousands of years. The natural rotation of Earth around the sun forms the basis for the astronomical calendar, in which we define seasons with two solstices and two equinoxes. Earth’s tilt and the sun’s alignment over the equator determine both the solstices and equinoxes.

The equinoxes mark the times when the sun passes directly above the equator. In the Northern Hemisphere, the summer solstice falls on or around June 21, the winter solstice on or around December 22, the vernal or spring equinox on or around March 21, and the autumnal equinox on or around September 22. These seasons are reversed but begin on the same dates in the Southern Hemisphere.


Because Earth actually travels around the sun in 365.24 days, an extra day is needed every fourth year, creating what we know as Leap Year. This also causes the exact date of the solstices and equinoxes to vary. Additionally, the elliptical shape of Earth’s orbit around the sun causes the lengths of the astronomical seasons to vary between 89 and 93 days. These variations in season length and season start would make it very difficult to consistently compare climatological statistics for a particular season from one year to the next. Thus, the meteorological seasons were born.

Meteorologists and climatologists break the seasons down into groupings of three months based on the annual temperature cycle as well as our calendar. We generally think of winter as the coldest time of the year and summer as the warmest time of the year, with spring and fall being the transition seasons, and that is what the meteorological seasons are based on. Meteorological spring includes March, April, and May; meteorological summer includes June, July, and August; meteorological fall includes September, October, and November; and meteorological winter includes December, January, and February.

Meteorological observing and forecasting led to the creation of these seasons, and they are more closely tied to our monthly civil calendar than the astronomical seasons are. The length of the meteorological seasons is also more consistent, ranging from 90 days for winter of a non-leap year to 92 days for spring and summer. By following the civil calendar and having less variation in season length and season start, it becomes much easier to calculate seasonal statistics from the monthly statistics, both of which are very useful for agriculture, commerce, and a variety of other purposes.

Information Courtesy NOAA

WDRB Meteorologist Jeremy Kappell

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Large Upper System to bring Cold, Wet and Stormy Conditions!

We've been tracking a the development of a very large, and slow moving upper level storm system currently swirling over the Great Lakes. 


Unfortunately, this storm is heading in our direction and will bring an abrupt end to the beautiful conditions we've been enjoying today.  

Let's time it out with AdvanceTrak...

AT starts us off dry and cool in the morning with 50's out the door.


Sunshine gives way to increasing clouds by late morning with the chance for showers developing into Southern Indiana.


AT warms us quickly into the lower 70's for metro as showers approach out of Southern Indiana by early afternoon.


If we get enough heating, then thunderstorms will be possible into the afternoon hours.


AT shows a line of storms exploding over our Kentucky counties during the afternoon with small hail and gusty winds possible.


Activity exits our southeastern counties during the evening hours while diminishing.


Unfortunately, this could be the first of several rounds of rain this week.

The reason for the sudden increase in rain chances has to do with the evolution of the upper storm system which will become "cut-off" from the main flow.  


The low looks to dive south and then stall out over the Lower Ohio Valley bringing clouds, very cool temps and wet conditions.


The latest data suggests it will be parked right over our area on Friday bringing the possibility of heavy rain.


Finally, it looks like this low begins to pull back away from us by late Saturday and into the second half of the weekend with improving conditions expected.


What do I think?

It's time to find that parka!  I think rain is likely each of the next three days with heavy rain possible on Wednesday and again Friday.  In addition, the clouds and cold air associated with this storm will create for some very chilly conditions as highs might struggle to even escape the 50's on Thursday!  BRRR!!  A far cry from the 90's over the weekend!!

Eventually, the low will lift with gradually warmer conditions expected as we head into next week.  

WDRB Meteorologist Jeremy Kappell

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Typhoon Megi mangled Hualien, Taiwan Tuesday with sustained winds over 100 mph, massive waves and tremendous amounts of rain. Get a load of this, Megi is the fourth storm to affect Taiwan this year! Nepartak struck the island in July, followed by Meranti and Malakas in September. Megi is 310 miles in diameter and is expected to quickly pass over the island's steep central mountain range. More than 8,000 people had been evacuated, mostly from areas at risk of landslides or floods. Watch this video filmed as Megi smashed into the coast of Taiwan...

Video Courtesy: Earth Uncut TV


Image Courtesy: NASA


Atmospheric Pepto Bismol Needed...Bumpy Times Ahead

From Jude Redfield...

    A potent low pressure heads in from the Great Lakes tomorrow. This is going to touch off pop up showers and storms starting Wednesday. Brief downpours and small hail will be likely in some of the stronger storms. Tomorrow's rain chance is around 50%. Thursday and Friday's rain chances stay close to that 50% range.  Keep in mind these showers will pull down cold air during the day. When and where the rain comes down temps at times will dip into the 50s. 


    Wednesday should start quiet with partly cloudy skies. Clouds quickly spill in and then the showers and storms fire up.





    Thursday and Friday offer mostly cloudy skies most of the time with high temps only hitting the mid 60s...when it isn't raining. Remember where it rains is where the temps cool into the 50s.


The pattern the remainder of the week is unsettled and will require some atmospheric Pepto Bismol LOL  -Jude Redfield-


OCTOBER OUTLOOK: Forecasting for Fall Foliage!

While it is becoming clear that a slow moving, cut-off low pressure system in the upper levels will keep our temps below normal for much of this final week of September, that pattern looks to change into the first week of October and perhaps beyond. 


The latest run of the GFS is projecting the development of an ENORMOUS upper ridge of high pressure that looks to span the entire Eastern half of North America by midweek next week.  


This looks to bring back the unseasonable warmth to start off October.  Today's run of the CFS (a GFS based climate model) seems to be picking up on this trend and is projecting warmer than normal temps across the Eastern US and Canada during the first 10 days of the month.  Locally, the CFS has us at about 1 to 2 degrees C above normal during the period. 


Looking further out, the CFS is keeping most of North America warmer than normal through the first 25 days of the month.


The Climate Prediction Center agrees with this forecast and keeps us in a 40% for above normal temps during the month.


CPC also has us in near normal precip for the month, which typically October is one of our driest months of the year averaging only around 3 inches of rain. 


How will this impact Fall Foliage?

As long as we see near normal precip over the next few weeks and no major wind events, then I think we will be in good shape with fall colors this year.  

Although the recent dry and hot stretch has stressed our hardwoods a bit lately, we have managed to avoid drought which should work in our favor.  

24 hour temp change

Fall foliage peaks during the last two weeks of October.  Hopefully our weather cooperates.  


WDRB Meteorologist Jeremy Kappell

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On Sept. 18th, Frankie Lucena of Cabo Rojo, Puerto Rico, photographed an enormous sprite over the Caribbean Sea. Sprites are large-scale electrical discharges that occur high above thunderstorm clouds, or cumulonimbus, giving rise to a quite varied range of visual shapes flickering in the night sky. They are triggered by the discharges of positive lightning between an underlying thundercloud and the ground. Check this out...

Video Courtesy: Frankie Lucena

Three types of sprites have been categorized by Matthew 'Geoff' McHarg Ph.D. (U.AK) of the US AirForce Research Academy (and NASA). Using an image intensifier on the front of super slow motion camera McHarg and his researchers have named the sprites based on their visual appearance.

  • Jellyfish sprite - very large, up to 30 by 30 miles (48 by 48 km).
  • Carrot sprite
  • C or Column sprite. These are large scale electrical discharges above the earth that are still not totally understood.

Sprites are sometimes inaccurately called upper-atmospheric lightning. However, sprites are cold plasma phenomena that lack the hot channel temperatures of  tropospheric lightning, so they are more akin to fluorescent tube discharges than to lightning discharges.