Monday, March 7, 2016

Monitoring Flooding & Severe Weather Potential for Later in the Week

The First Alert Storm Team is continuing to monitor the potential for flooding rains and severe weather later in the week. A slow-moving, potent storm system already producing flooding rains and severe weather in parts of California is the one that could be problematic for us in the coming days.

Here's what we know: parts of the Southern Plains and northern Gulf Coast are all but certain to receive excessive rainfall in the coming days. The devil lies in the details. It's difficult, if not almost impossible to pinpoint which areas will be hardest hit but we're gradually getting a better idea of where the greatest threats may lie.

Locally, we can expect scattered showers and a few t-storms to arrive by Tuesday afternoon, but neither flooding rains nor severe weather is anticipated in this initial round of wet weather. Those threats should remain to our west on Tuesday.

Our latest model runs have even started to indicate a somewhat slower arrival of the most active showers and t-storms, perhaps holding off until late Wednesday or even Thursday. It's during this timeframe though that severe weather appears to be possible along with our first real threat of locally heavy rains. The Storm Prediction Center does have areas from near Baton Rouge westward under a 'Slight Risk' of severe weather during this time, with a lower 'Marginal Risk' east of Baton Rouge.

The biggest threat to the greatest number of people during the remainder of the week will be heavy, potentially flooding rainfall. In a modestly encouraging trend, our last couple of rounds of computer model guidance have trimmed back forecast rain numbers. However, we still think widespread totals of 3" to 6" will be common in the WAFB viewing area through Saturday, with the potential for much higher amounts in localized areas. As it stands right now, a greater threat appears to be for areas near the Louisiana/Texas line extending northward to the ArkLaTex.

While the greatest threat does appear to be to our west, the weather pattern expected later in the week will favor the development of 'training' bands of t-storms -- clusters of storms moving over the same areas like train cars moving along a track. Anyone unfortunate enough to caught underneath one of these bands could easily pick up rains in excess of the 3" to 6" we're currently forecasting on average across the area.

With the expected heavy rains, we'll also have to monitor rising river levels later in the week. Additionally, persistent southerly winds mean that coastal flooding could be an issue in spots. Those southerly winds would also result in water backing up in the lower reaches of the Amite and Tickfaw river basins, slowing the ability of rain water to drain into Lake Maurepas.

Tuesday, March 1, 2016

Commentary: Is a gap in south Louisiana radar coverage putting lives at risk?

The final numbers are in -- 12 tornadoes touched down on what was a terrible Tuesday, February 23rd for south Louisiana. Included in that count were some monster twisters like the EF-3 from northern Assumption Parish that went on to devastate the Sugar Hill RV Park in Convent as an EF-2, leaving 2 dead and as many as 75 injured. Let's not forget the EF-2 that injured 17 in LaPlace or the EF-2 that plowed through Livingston with one woman hanging on to her bathroom door for dear life as the entire top of her home was sheared off.

Leveled home near Willow Street in Livingston. (Source: WAFB)

It appears to be the worst tornado outbreak on record for south Louisiana in records that date back to 1950.

Map of the 12 confirmed tornadoes in south Louisiana on Feb. 23, 2016.

And it could have been worse, much worse, if not for the heroic efforts of forecasters at the National Weather Service New Orleans/Baton Rouge office in Slidell issuing rapid-fire warnings for the tornado-producing storms on Tuesday.

But I noticed something on that day that most of you probably didn't. There were a few tornadoes that got very little warning and at least one that got none at all. That particular storm actually fell under the warning responsibility of the National Weather Service Lake Charles office.

But let me be clear: the lack of warning is by no fault of forecasters with the National Weather Service.

The issue, I believe, stems mostly from poor, if not unacceptable radar coverage for parts of south Louisiana.

The Problem: Poor Radar Coverage

The map below shows National Weather Service NEXRAD (Next-generation Radar) Doppler radar coverage at 4,000 feet and below (green), and 6,000 feet and below (yellow). Earth's curvature and the fact that radar is tilted a minimum of 0.5° above horizontal while scanning mean that the radar beam gradually gets higher and higher the farther it gets away from the radar site. What stands out is that because of the curvature and tilt issues, areas from Baton Rouge to Lafayette southward to the coast and northward toward Natchez, Mississippi have no radar coverage in the key atmospheric levels needed for tornado detection. The nearest NEXRAD radars to Baton Rouge are 80 miles to the east in Slidell and 120 miles to the west in Lake Charles.

Radar coverage at ≤4,000 feet (green) and at ≤6,000 feet (yellow). (Source: NOAA/NCEI)

A wider view of the same map shows that Baton Rouge appears to be the second largest city anywhere in the southern U.S. without reliable NEXRAD radar coverage, with only Charlotte, NC having a larger population of people with such poor coverage. Later in this article, you'll see how meteorologists and leaders in Charlotte have taken action to address that problem.

Radar coverage at ≤4,000 feet (green) and at ≤6,000 feet (yellow). (Source: NOAA/NCEI)

If we look at areas with radar coverage at 6,000 - 10,000 feet (blue in map below), metro Baton Rouge finally gets into the mix, but there are still portions of south Louisiana left out. Much of St. Mary Parish remains without good radar coverage even at this level, including areas around Franklin and Baldwin. And as it turns out, that's one of the areas where a tornado was missed on Tuesday. No warning was ever issued, but an EF-1 touched down in that area according to the National Weather Service Lake Charles. Two businesses and 28 homes were damaged, along with 20 telephone poles being snapped.

And, oh by the way, it was this same severe thunderstorm that went on to produce an EF-3 tornado near Paincourtville and EF-2 damage and casualties in Convent. I don't think it was coincidence that the St. Mary Parish tornado came and went without a warning.

Same as above with coverage of ≤10,000 feet added in blue. The location of a confirmed EF-1 tornado in St. Mary Parish is shown, clearly in an area with poor radar coverage. (Source: NOAA/NCEI & Steve Caparotta)

Secondary Problem: Little Reliable Backup

In another illustration of our radar coverage vulnerability in south Louisiana, a lightning strike took down the National Weather Service Doppler radar in Slidell just before 5 p.m. on Tuesday as severe weather was ongoing. The map below shows that there were 2 active Tornado Warnings in southeast Louisiana at that time in addition to ongoing Tornado Watches. The radar wasn't restored to service until late the next day, meaning the National Weather Service in Slidell had to rely primarily on the radar in Mobile, Alabama to issue warnings for southeast Louisiana and south Mississippi.

There is also a Terminal Doppler Weather Radar (TDWR) located in St. Charles Parish that can supplement coverage as needed, but it's much lower power than the NWS NEXRAD radars and has a much shorter range. It does NOT provide reliable coverage of Baton Rouge or much of the area in south Louisiana's radar gap. The TDWR located in St. Charles Parish was installed primarily to aid in wind shear and heavy rain detection for Louis Armstrong International Airport in Kenner.

Radar from 4:50 p.m. on Tuesday, Feb. 23, 2016 with current watches and warnings overlaid. (Credit: Iowa Environmental Mesonet)

Now imagine this nightmare scenario. That same lightning strike happens 2 hours sooner and meteorologists are left 'flying blind' (or close to it) as the powerful EF-3 tornado strikes Assumption Parish and continues as an EF-2 into St. James killing 2 and injuring dozens more. Several people in those areas have credited the warnings for saving their lives. Had the radar in Slidell gone down just a little earlier, those warnings may not have been issued and the casualty numbers could have been much higher.

The Solution?

Chances are if you've made it this far into the article, you now understand and agree that south Louisiana needs better radar coverage. So why don't we have it? As is the case with so many things in life, much of it boils down to dollars and cents.

The installation cost for a new Doppler radar runs into the millions of dollars and some estimates indicate annual maintenance and upkeep can run into the hundreds of thousands of dollars.

Additionally, you need a team of qualified personnel both to operate and maintain a radar at any given location. That's why our nation's Doppler radars are most often collocated with National Weather Service offices.

In the wake of an undetected tornado near Charlotte, NC in 2012, a bill was introduced in Congress that would require a radar within 55 miles of cities with a population of at least 700,000. If passed, that solves Charlotte's problem, but certainly not ours in south Louisiana.

I do think our Louisiana congressional delegation should lobby for a new NEXRAD installation near or around Baton Rouge, but if that doesn't occur or fails to gain traction, there are other possible solutions.

The University of Louisiana at Monroe (ULM) recently completed installation of a Doppler radar that was funded by a $3 million grant through the Louisiana Governor's Office of Homeland Security and Emergency Preparedness (GOHSEP). That radar is set to go online any day now.

New Doppler Radar at ULM. (Creidt: ULM)
ULM's radar is a great step forward and one that I believe was needed in northeast Louisiana. It also gives an added boost to ULM's Atmospheric Sciences program which has produced a number of very talented and successful meteorologists through the years.

But what a shame that an area centered around our state's capital has some of the poorest radar coverage in our state and is also among the poorest in the U.S. What a shame that an area that houses so much of the state's industry and its 'chemical corridor' -- an area that one could argue is very vulnerable to severe weather -- has very little reliable coverage.

The map below shows the number of lightning flashes per square mile from 2005-2014. If lightning is assumed to be a rough proxy for 'active' or potentially severe weather, it becomes clear that one would be hard pressed to find an area anywhere in the U.S. more in need of better radar coverage or where there would be better bang for the buck on a new installation.

Number of lightning flashes per square mile, 2005-2014. (Credit: Vaisala)

The way I see it, there's a real opportunity for our local and state leaders to lobby hard for an installation near or at LSU. The state's flagship university is home to a long-standing, well-respected Geography Department that houses a number of faculty with weather and climate backgrounds. I am currently a graduate student in that department pursuing my Ph.D., having already completed my master's degree at LSU in 2008.

LSU is also home to both the Louisiana State Office of Climatology and the Southern Regional Climate Center, an agency that collects and disseminates weather and climate information for multiple states in the South.

I believe a joint effort by the Dept. of Geography, the climate centers housed at LSU, LSU President F. King Alexander, the National Weather Service, and our congressional delegation could go a long way in trying to secure a badly-needed radar for Baton Rouge and surrounding areas. Not only could it be a life-saving device, but also an invaluable recruiting and research tool for multiple programs at LSU.

I know money is tight, but let's get moving on this. Lives could depend on it.

Monday, February 15, 2016

Strong to Severe Storms Possible Today

A Tornado Watch has been posted for much of the WAFB viewing area through 6 p.m. this evening.

An approaching cold front will produce numerous showers and t-storms today, with the main action expected to arrive in metro Baton Rouge near or shortly after lunchtime. You can see that computer model guidance is in good agreement with this scenario, showing the main line moving into Baton Rouge roughly around 1 p.m.

The primary threats from any strong storms will be large hail and damaging winds, but an isolated tornado can't be ruled out.

Storms should end from west-to-east by late afternoon into early evening as the cold front moves eastward.

Stay with the WAFB First Alert Storm Team on air and online for updates as needed through the day. If you witness any severe weather, relay your reports to us by sending pictures and/or video to or through our Facebook and Twitter accounts.

Wednesday, January 27, 2016

Blizzard of 2016 -- could it ever happen here?

The Blizzard of 2016. Snowmageddon. Snowzilla. Jonas. That thing that made the U.S. House of Representatives cancel all votes for an entire week. Call it what you want, but the winter storm that raked parts of the mid-Atlantic and Northeast this past weekend was a beast.

Widespread snow totals of 1 to 3 feet were recorded, with the largest daily snowfall on record measured in New York City's Central Park (26.6"). Record and near-record snows were also measured in other major cities, including Baltimore, Washington D.C., and Philadelphia.

Snowy scene from Central Park in New York City posted by Instagram user @ozgurdonmaz

So could a winter storm of that magnitude ever occur here along the Gulf Coast?

No way, right?

You might be surprised.

On the 14th and 15th of February 1895, Mother Nature produced a snowstorm in the Deep South that seems inconceivable to those of us who have spent our entire lives along the Gulf Coast. One to two feet of snow fell in many spots around south Louisiana, including a still standing record of 12.5" here in Baton Rouge. And in the "Frog Capital of the World", Rayne, LA, a city used to dealing with frog-strangling rains instead was buried under 24", or 2 feet of snow. Coming in a close second was Lake Charles with a total of 22".

Selected snow totals from February 14-15, 1895 was published in Monthly Weather Review.

What makes the 1895 event even more impressive is that the next biggest snowstorm in Baton Rouge produced 6" of snow in 1914, or a half-foot less than that record value. Further examination of the biggest snow events for Baton Rouge shows that we've recorded no more than 3.5" in a single storm since World War I.

How do we know about the 1895 snowstorm along the Gulf Coast? Information is limited, but a brief account of the impacts in Louisiana can be found in the American Meteorological Society's publication Monthly Weather Review:

My favorite line from that summary is this:

     "Within a week after this extreme cold the ground was covered with a mantle of snow to a depth from a few inches at the Mississippi jetties to as much as two feet in southwest Louisiana."

In other words, the snow extended all the way down to the mouth of the Mississippi River. And "mantle of snow" is a phrase I'll have to tuck away in my back pocket for future snowstorms.

I've been able to dig up just a couple of pictures from the historic event, one out of New Orleans and the other from Lake Charles.

Canal Street in New Orleans during the February 1895 snowstorm.

Lake Charles family in the snow from February 1895. Courtesy: McNeese State University.

The few accounts of the storm that do exist point toward low pressure moving eastward through the Gulf of Mexico as the likely culprit behind the record snows. That fits what we most often see when there is a threat of ice and/or snow along the Gulf Coast.

The "Daily Weather Maps" produced by the then U.S. Weather Bureau show a low headed toward the Florida Peninsula by February 15, but the maps likely underestimate the intensity of the low due to the sparsity of weather observations.

Daily Weather Map from the U.S. Weather Bureau for Feb. 14, 1895.

Daily Weather Map from the U.S. Weather Bureau for Feb. 15, 1895.
So could this ever happen again? Sure. 

Is it likely? Not very. 

We've been through 21 Baton Rouge mayors, 29 Louisiana governors and hurricanes such as Audrey, Betsy, Camille, Andrew, Katrina, Rita and Gustav in the time since we last saw a blockbuster snowstorm in south Louisiana. 

But, hey, the Saints also won a Super Bowl during that stretch. Who ever thought that would happen?

Thursday, December 10, 2015

Strong to Severe Storms Possible on Sunday

Fog has been our primary weather concern over the last few days, but our focus is shifting to the potential for some strong to severe storms on Sunday. The storms will be driven by a potent upper-level storm system and associated cold front moving through the Deep South this weekend.

Storms will begin to develop along and in advance of the cold front in parts of Texas by late Saturday.

The Storm Prediction Center has placed eastern Texas, parts of Oklahoma, Arkansas, Missouri, and NW Louisiana under a 'slight risk' of severe weather from Saturday into the early morning hours of Sunday due to the anticipated storm development.

The Storm Prediction Center (SPC) issues a detailed severe weather outlook through 3 days, with a more general summary for days 4 through 8. The latest 'Day 4' outlook covering Sunday still shows the SPC highlighting the potential for severe weather locally. The primary threat from any strong storms would be damaging winds, but an isolated tornado can't be ruled out.

The cold front should move through the area fairly quickly on Sunday limiting the potential for flooding rains, but we're still expecting 1" to 2" of rainfall on average, with locally higher amounts.

The bottom line: make sure you've got a reliable way to keep abreast of any threatening weather that develops on Sunday. A NOAA Weather Radio is a great tool to have in your arsenal and of course we encourage you to download our free weather app at the following links:

Tuesday, November 17, 2015

Severe Weather Threat Arriving

We've warned you for close to a week about to the potential for severe weather and that threat appears to be playing out. A Tornado Watch is posted for metro Baton Rouge and SW Mississippi through 8 p.m., with a Watch for Acadiana and SW Louisiana through 4 p.m.

You may think that with the watch set to expire at 8 p.m. locally, that would mark the end of the severe weather threat. However, we're likely to either see an extension of that watch or a new watch issued later tonight. We are essentially facing the potential for two separate rounds of severe weather. The initial round will be in the form of scattered strong to severe storms well in advance of the cold front. These 'discrete' thunderstorm cells will have a somewhat better chance of becoming tornadic, although any tornadoes are still expected to be isolated.

The second, primary threat of severe weather will accompany a squall line. Typically squall lines produce more in the way of straight-line wind damage, but isolated tornadoes will remain possible. It is the squall line that will impact most of the area late tonight. Radar trends suggest that the models may be a little too slow in moving the squall line eastward, but look for the primary threat window to be roughly 8 p.m. - midnight for metro Baton Rouge.

A Flash Flood Watch also remains in effect for all of our viewing area through 10 a.m. on Wednesday. 

We don't expect rains as bad as what we experienced in late October, but widespread totals of 2" to 4" can be expected, with locally higher amounts possible.

Stay with the First Alert Storm Team throughout the remainder of today and tonight as we track the approaching storms. We'll have coverage on air, online and in our free weather app. Also, make sure you have a way to receive weather warnings before going to bed tonight. We highly recommend a NOAA Weather Radio which will sound an alarm if a warning is issued for your area.

Thursday, October 29, 2015

Halloween Gloom Compliments of Mother Nature

The threat of rain and storms has forced most communities around the area to move Trick-or-Treating to Friday night (click here for updated times). While there may not be any real legal punch behind the move, the not-no-subtle suggestion from area leaders is the right move to make.

It's simple -- Friday likely stays dry while Mother Nature may outdo ghosts and goblins with the fright factor on Halloween.

Heading into Saturday, the threatening weather has also prompted the 10/31 Consortium to move their planned parade from a 2 p.m. start to 9:30 a.m. instead. That should be good enough to avoid the worst of the weather, but showers will be possible, even during the morning hours.

Outside of impacts to Trick-or-Treating and other Halloween events, the big story for the weekend will center around rain amounts and the potential for additional flooding. Most of our computer guidance paints anywhere from 1" to 4" of rain across the area through the weekend. However, our in-house RPM model has had some runs today with bands of even higher amounts. The latest available run as of Thursday evening delivers widespread 3" to 5" totals, with locally higher amounts.

Most area rivers have already crested or are near crest tonight, but we'll need to keep an eye on the potential for additional rises over the weekend, depending on exactly how much rain we receive.

At this point, we don't expect widespread severe weather, but a few isolated strong storms will be possible, particularly Saturday afternoon and evening. The Storm Prediction Center has our area under a 'marginal' risk for severe weather.

We'll be here through the weekend to keep you updated on the expected rains and any strong storms that may develop. You can also track the rains on your smartphone or tablet using our free weather app:

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