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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Tuesday, October 27, 2015

Weekend Soaking in Perspective...and Another Round Ahead?

By Steve Caparotta

Were you among the plethora of south Louisiana residents begging for some rainfall through the first few weeks of October? I was certainly in that crowd, growing tired of running my sprinkler to keep my lawn and garden from wilting in the dry and warm weather. But as they say, be careful what you wish for.

In a remarkable turn of events, we went from 'extreme drought' in some locations to dealing with flooding in the course of just a couple of days. In fact, the most recent Drought Monitor that was released last Thursday, October 20th, had more than 50% of Louisiana classified as being in an 'extreme drought', with over 13% of North Louisiana under the worst classification of 'exceptional drought'. It's fair to say the map below will see significant changes when a new update is released this Thursday.

As it turns out, a stretch of 24 days without measurable rain in Baton Rouge and much of the surrounding area and an overall dry stretch since the beginning of September turned out to be a blessing this past weekend. While we certainly dealt with some localized flooding in urban areas and continue to monitor rising rivers, it could have been much worse had there been any rain of consequence in the prior days and weeks.

How big of a rain event did we see this past weekend? For most of the area, it was the most significant multi-day rain since Tropical Storm Allison produced flooding in 2001. Sunday's rainfall ranks as the 5th largest single-day total in Baton Rouge in records that date back to 1892!

And the 2-day rain total for Saturday and Sunday in Baton Rouge ranks as the 6th largest 2-day event since 1892.

It's also remarkable to consider that through October 23rd, Baton Rouge Metro had only recorded a trace of rainfall. Three days later, 2015 stood as the third wettest October on record!

One other way to measure a rain event is by using a tool that climatologists call 'recurrence intervals'. Without getting into the dirty (and boring to many) details, recurrence intervals are a statistical measure of how frequently a given location can expect certain rain amounts over a given duration. Using a NOAA tool available online, we find that the 2-day rain total of just under 11 inches in Baton Rouge is a roughly 1-in-25-year event. In other words, people in Baton Rouge can expect to see rains like this past weekend roughly once every 25 years when averaged over a LONG period of time. Another way of looking at it is that there's a 4% chance in any given year of seeing a 2-day rain like this past weekend.

Recurrence intervals for rainfall in Baton Rouge. Source:
While most of our neighborhoods are beginning to dry out, rivers are still rising and we'll see additional problems through the week for those who live along or near rivers. And the bad news? It looks like we've got more rain on the way for the weekend.

The rains will be somewhat of a double-whammy, not only arriving over the weekend, but potentially turning into a real issue for Trick-or-Treaters and Halloween parties. There's still some uncertainty in the timing of the rains over the weekend, but it looks like the wet weather will begin to arrive by Saturday afternoon and continue into Sunday.

The map below shows that NOAA's Weather Prediction Center is already forecasting an additional 2" to 4" of rain for much of our area over the weekend.

One more thing to note that we've already mentioned at times in our weathercasts. One of the strongest El Niño events on record is ongoing in the Pacific. History tells us that during El Niño events, fall and winter tend to see above-normal rainfall along the Gulf Coast. With that in mind, it's quite possible that these rain events will only become more frequent in the coming months. The currently 3-month outlook for Nov-Jan from NOAA's Climate Prediction Center is in line with that thinking, calling for above-normal chances for above-normal precipitation in our region.

Stay dry, everyone, and count on the WAFB First Alert Storm Team on air, online and on your mobile device for the latest on any storm systems headed our way.

Friday, July 3, 2015

Scattered Storms Return for the Holiday Weekend

By Jay Grymes & Steve Caparotta

July 3rd WAFB First Alert Quickcast:

- back to scattered afternoon t-storms for the independence Day weekend
- drier and a little warmer for next week

Happy 4th to you and yours!

We doubt that anyone is complaining about our back-to-back dry days, thanks to high pressure at the mid and upper levels putting the clamps on afternoon thundershower development.

Unfortunately, the “lid” comes off the atmosphere over the weekend and we return to scattered afternoon showers and t-storms for both Saturday and Sunday. In fact, we’re leaning towards “rain likely” for Saturday (rain chances at 50% to 60% for Saturday afternoon), and there is a potential for a few strong to severe storms in the WAFB area over the two-day span.

The upper-level high (a mid/upper-air ridge, the “lid” on the pot) that put the brakes on afternoon rains yesterday and today will give ground over the weekend. That will let our moist and unstable Gulf air do its thing: build mid-day and afternoon showers and storms without an inhibitor to slow their vertical growth. Neither day will result in all-day rains for your backyard, but we expect a pretty active radar depiction for both afternoons as individual t-storms build, move and subside through the day. If you’ve got outdoor plans on either day, make sure that you have an indoor or under-cover option ready to go.

After muggy morning starts in the low to mid 70°s for both Saturday and Sunday around metro Baton Rouge, look for temperatures to climb into the upper 80°s to around 90° before the clouds and rains knock the temperatures back through the afternoon.

As for the Saturday evening “Fireworks on the Levee,” we expect the rains to have dissipated by showtime, but we could still have isolated rains in the area as late as 7:00 or even 8:00pm. We’re thinking that temperatures for the 9:00pm showtime will be in the upper 70°s to low 80°s on the levee.

Into next week, the ridge returns, taking rain chances back down into the ”isolated” category for just about every day next week -- yep, too bad the ridge had to retreat during the weekend. With the drier pattern in the forecast for next week, plan for muggy morning sunrises in the low to mid 70°s for most WAFB communities, with highs in the low 90°s just about every day.

Thursday, July 2, 2015

Mainly Dry Again for Friday

By Jay Grymes & Steve Caparotta

July 2nd WAFB First Alert Quickcast:
- hot, breezy and mostly dry for Friday
- scattered showers & t-storms expected for both weekend days

Okay, our “mainly dry” forecast for today took a big hit in a number of neighborhoods before 7:00am thanks to a band of mainly-light showers draped over the viewing area. Those showers fizzled out by or before mid-morning and the gray cloud deck had largely thinned before lunchtime. With the thinning clouds, mid-day and afternoon sunshine took temperatures into the 90°s for the afternoon.

Even as late as 3:00pm this afternoon, Doppler was “all clear” across the WAFB viewing area. A rogue, spotty shower or two might pop-up during the late afternoon or early evening, but we expect that just about everyone stays dry into the evening and overnight too.

Our Friday forecast calls for another mainly-dry day like today … with the big exception being no morning showers like some of us experienced this morning. After a muggy Friday morning start in the low to mid 70°s for many WAFB communities, we’ll climb once again into the low 90°s for Friday afternoon, with spotty showers, at best. Add in the afternoon humidity and that low 90° reading will ‘feel like’ 100° or more at the peak of the afternoon heat. Then it’s a warm and dry Friday evening and mostly fair skies into the night.

Out mostly-dry Thursday and Friday are courtesy of a western U.S. upper-air ridge building just a bit farther east. That ridge has pushed drier and slightly warmer air into the middle levels over the Bayou State -- and that serves as a rain-cloud inhibitor.

Unfortunately, the dry spell doesn’t hold through the weekend. The ridge softens and retreats westward allowing our locally-unstable air a better chance to build vertically during the afternoons: bigger afternoon cumulus clouds usually means more rain-clouds and better rain coverage. We’re still not too concerned about any kind of severe weather threat for either Saturday or Sunday, but we’ll go with rain chances at 40% to 50% or so for both days. Of course, with those elevated rain chances, we can’t rule out one or two strong storms on either afternoon.

So be ready to dodge the rains during both afternoons. We don’t anticipate all-day rains in either case and not everyone gets wet each day … but have a plan to get out of the weather should storms roll through your neighborhood. The good news is that we expect Saturday’s mainly-afternoon rains to be out of the way for Saturday evening’s fireworks and festivities.

Headed into next week, upper-level ridging builds back over the area, knocking rain chances back to around 20% to 30% for just about every afternoon. (Too bad that isn’t the cast for the weekend, eh?)