Saturday, August 31, 2013

Rain Not An Issue for Labor Day Weekend

Rain won't be much of an issue for your Labor Day weekend.  Many will get the extra day off on Monday so lets talk about the forecast.  Saturday will be a completely dry day.  Heat and humidity will be on the rise though.  Highs this afternoon should top out in the low to mid 90°s.  Factor in the slowly rising humidity and heat index values will make it feel more like the upper 90°s.

High pressure will shift and weaken on Sunday.  That will allow for a very slight mention of rain.  A spot or two of wet weather may appear on Titan 9 Doppler Radar.  Don't cancel any outdoor plans if you have them.  Rain coverage is only expected to be around 10% of the entire WAFB viewing area.  Highs will once again climb into the low to mid 90°s.  Feels like temperatures may reach 100°.

Labor Day itself will see another slight increase in rain chances.  Iso'd showers and storms will pop up Monday afternoon.  Once again don't cancel any outdoor plans as rain coverage will be about 20%.  Highs will be in the low to mid 90°s with feels like temperatures reaching the low triple digits.

If you are worried about the wet stuff we have some great tools for you to use.  Download our free Titan 9 Weather App in your app store on your smart phone.  Also head to our website and view our interactive radar.  You can get a street view perspective.  Link: Interactive Radar

Friday, August 30, 2013

A Bit Hotter, More Humid This Weekend

We enjoyed another relatively pleasant start in the upper 60°s in many WAFB neighborhoods this morning, but it was likely our last morning in the 60°s for a while. Both temperatures and humidity will be on the way up as we head into the holiday weekend.

Saturday starts out with temps in the lower 70°s for most and afternoon highs will climb into the lower 90°s under partly cloudy skies. We can’t completely rule out a stray shower, but the vast majority of you should remain dry.

A ridge of high pressure that has kept us rain-free for several days will shift just far enough to the west to allow a few showers and t-storms to return our forecast by Sunday. However, don’t worry too much about rain if you have outdoor plans for the extended weekend. We’re only going with a 20% chance of showers and t-storms on both Sunday and Monday (Labor Day).

The extended outlook points toward somewhat better rain chances by the mid portion of next week as a cool front attempts to approach from the north. At this point, it looks like the front won’t actually move through the area, meaning warm and humid conditions will likely continue into the end of next week.

In the tropics, we continue to track a pair of systems this afternoon, but neither is of much concern to us at this point. A tropical wave about 600 miles east of the Lesser Antilles (eastern Caribbean) remains disorganized and isn’t likely to do much over the next couple of days. Farther to the east, a strong tropical wave is emerging from the west coast of Africa and shows some potential for development. However, even if it does manage to organize, it will likely remain over the open Atlantic.

Given that we currently don’t have a named tropical system, that makes it likely we’ll make it through the month of August without seeing the season’s first hurricane in the Atlantic. Historically, the average formation date for the first hurricane is August 10. Since 1960, there have only been 5 seasons that saw the first hurricane after August: 1967, 1984, 1988, 2001, and 2002. So does the lack of hurricanes so far mean the remainder of the season will stay quiet? Probably not. The 5 other seasons that got off to a relatively slow start went on to produce an average of 6 hurricanes. Louisiana was impacted by 2 hurricanes in those years – Florence in 1988 and Lili in 2002. The 1988 season also produced Gilbert, one of the most intense hurricanes ever observed in the Atlantic. Bottom line – don’t let the slow start to this hurricane season lull you to sleep!

Thursday, August 29, 2013

Hot, More Humid by the Weekend

By Jay Grymes & Steve Caparotta

** Remembering 2005’s Katrina ... and it was one year ago today that Isaac produced most of ‘his’ southeast Louisiana impacts.
Katrina made landfall at 6:10am along Plaquemines Parish near Buras with peak winds estimated at 125 mph.  But in the end, it wasn’t Katrina’s winds that produced so much destruction along the Gulf Coast but the extensive storm surge and failed engineering defenses.  In the end, Katrina resulted in an estimated 1200 fatalities and losses in excess of $100 billion according to the National Hurricane Center. **

Closer to home ... today was a better August day than we had expected, with a comfortable morning low in the mid to upper 60°s and an afternoon high around 90°.  And maybe more importantly, dew points stayed lower than expected, ranging in the mid to upper 60°s through the day.
We will see a modest rise in dew points, but not until we are well into the day on Friday.  So plan on another comfortable morning for Friday: sunrise temps in the upper 60°s for metro Baton Rouge under mainly clear skies.  We do think that Friday will be a bit warmer than today, with temps climbing into the low to mid 90°s and a slight increase in humidity levels by the afternoon -- but still not oppressive.
The Labor Day weekend looks pretty good, although we still think that at least some neighborhoods could be flirting with afternoon highs in the mid 90°s for Saturday and again on Sunday.  Saturday stays mainly dry, but the humidity will have returned to more August-like levels.  By Sunday, the warmth and low-level moisture should produce some afternoon t-showers, with isolated afternoon rains also expected for Labor Day Monday.

We’re going with scattered mainly-afternoon rains for Tuesday and Wednesday, with a return to isolated rains for Thursday.
In the tropics, no threats at all for Gulf interests but there are a couple of areas to watch -- a wave located roughly 1000 miles east of the Lesser Antilles and a vigorous tropical wave making its wave off the west coast of Africa.  The wave over the open Atlantic appears headed into a less favorable environment in the coming days and shows no imminent development potential.  As for the wave coming off of Africa, it may move into a somewhat favorable environment over the weekend.

Tuesday, August 27, 2013

Gradually Heating Up This Week

By Jay Grymes & Steve Caparotta

As promised, we got off to a pleasant start this morning – by August standards, at least – with lows ranging from the mid to upper 60°s around much of the area. But in somewhat of a surprise, we got an added bonus this afternoon as many WAFB neighborhoods failed to reach the 90° mark. That, combined with below-normal humidity, made for a pretty decent day given the time of year.

Radar has been rain-free around the viewing area today and that trend will likely continue for the better part of the workweek. An upper-level ridge of high pressure centered over the Plains and Midwest is building south, helping to put a ‘lid’ on the atmosphere and our rain chances locally. That building ridge will also translate into increasing heat through the remainder of the week, with highs potentially reaching the mid 90°s by Thursday and Friday. Humidity levels will also be on the rise late this week, meaning we’ll have the full summer ‘feel’ back by the weekend.

Speaking of the weekend, it will be an extended one for many, with Labor Day around the corner on Monday. High pressure should lessen its grip enough to allow for isolated showers and t-storms on Saturday and Sunday, but we’ll keep rain chances at 20% or less. The early outlook for Labor Day points toward scattered showers and t-storms (rain chances 30% to 40%) and highs in the lower 90°s.

We’re monitoring a couple of features in the tropics this afternoon, but nothing of immediate concern to us. A well-defined upper low is producing showers and t-storms near south Florida. Upper lows by nature are non-tropical in origin, so we’re not terribly concerned with development. The transition to a tropical system can happen on occasion, but for now, it’s just a feature to keep an eye on in the coming days.

The greatest potential for tropical development in the next few days is with an area of disturbed weather in the central Atlantic. This system appears to be a bit better organized this afternoon and has some potential to become a tropical depression or storm late this week into the weekend. It’s still way out there though, so we’ve got plenty of time to monitor its progress.

Monday, August 26, 2013

Hotter, Drier Week Ahead

By Jay Grymes & Steve Caparotta

** 21 year ago today (26 August 1992), Hurricane Andrew made ‘his’ second U.S. landfall along the coast of St. Mary Parish at approximately 3:30am. Wind speeds for the Louisiana landfall are estimated to have peaked at 115 mph (Category 3), but fortunately Andrew weakened quickly after landfall, with peak winds dropping to tropical-storm strength by mid-day. More importantly, media coverage of the devastation experienced across Florida two days prior to Andrew’s arrival in Louisiana was enough to send a message to Gulf Coast residents that this hurricane meant “business” -- prompting what was the largest coastal evacuation in history at that time. **

Speaking of tropical weather, Fernand (pronounced “fair-NAHN”) made landfall along the Mexican Gulf Coast at 11:45 PM last night, and was officially downgraded to a depression with the 10:00 AM NHC Advisory this morning. Remnants of the storm will continue to move inland and interaction with the region’s mountainous terrain will continue to disrupt the storm. Still, heavy rains and valley flooding will be a serious threat to local communities there.

For us, the northern Gulf easterly wave that skirted the Louisiana coast over the weekend continues to move a bit more slowly than many of us expected. As a result, we continue to see some isolated to scattered showers developing along the wave’s “backside” east-to-west flow. But the disturbance will continue to track westward into Texas, taking the isolated rains with it while drier air filters-in from the north and northeast.

Elsewhere in the tropics, a ‘wave’ far out in the open Atlantic may show some development in the coming days, but for now there is nothing showing imminent signs of organization anywhere in the basin.

Closer to home, today’s cloud-cover and passing showers -- including a handful of t-storms -- helped to slow the afternoon warm-up, keeping highs in the 80°s for many WAFB neighborhoods.

A broad upper-level ridge is settling over the central U.S. while surface high pressure builds into our viewing area from the east and northeast. The combination of these two features will mean mainly-dry days ahead with plenty of sunshine. In addition, dew point temps will drop into the 60°s for the next couple of days, making for comfortable mornings and “tolerable” afternoons. But be aware that the added sunshine and “dry” air (lowered dew points) in the coming days will allow afternoon temps to climb above-normal. In fact, many WAFB communities could see highs in the mid-90°s during the latter half of the work week.

So how long does the dry weather last? For now, we think just about everyone is rain-free through Friday. We’re getting some mixed signals for the weekend, so for now we’ll go with “mainly dry” for Saturday and Sunday too -- setting weekend rain chances at 20% or less for both days. 

Friday, August 23, 2013

Good Rain Chances This Weekend

By Jay Grymes & Steve Caparotta

Radar and satellite continue to highlight the easterly wave in the northern Gulf as it continues to slowly move from east-to-west.  The National Hurricane Center still gives this disturbance very little chance of developing into a tropical cyclone (a depression or tropical storm), but it is shaping up to be a rain-maker in the coming days for the southern parishes.
Due to its slow movement -- in fact, a tad slower today than we expected -- the WAFB viewing area remained under the influence of the “front” side (west side) of the wave -- this is the drier side of the disturbance.  With easterly waves, subsidence (sinking air) dominates the area ahead of the wave axis; generally the area behind the trough (the east side, the back side) is the wetter region.
So for today, we were a bit drier around the area than we had anticipated.
By Saturday, however, the wave will have moved far enough to the west to put southeastern Louisiana and SW Mississippi on the back side of the trough, enhancing rain chances for Saturday afternoon and into Sunday.  Still, we don’t anticipate an all-day rain for either day.  What we do expect is that the wave’s influence will be greatest for the coastal parishes, with its impact lessening as we head inland over the viewing area.
For Saturday, we think “rain likely” for our southern parishes, with rain chances running around 50-50 or so for those near and along the I-10/12 corridor.  Rain chances could be slightly lower still along the LA/MS state line, running around 40% to 50%.
For Sunday, we’re thinking about a 40% rain chance along the I-10/12, with those percentages running a little lower closer to the state line and a little higher closer to the Gulf.
What do those percentages tell us?  Don’t expect a “weekend wash-out” although you will want to check the radar on both days if you’re planning to spend time outside.  Nor are we anticipating widespread “big” rain totals over the weekend.  The southern parishes will likely see some decent totals, with some coastal locations possibly getting as much as 2” to 3” of rain through the weekend.  The current NWS Weather Prediction Center (WPC) forecasts call for weekend rain totals to fall off quickly from the coast to more inland sites, with current WPC projections running under 1” for the weekend for just about all locations north of the I-10/12.
By Monday, the wave should be inland over Texas.  And elsewhere in the tropics ... nothing of concern, at least for the time being.
Into next week, the extended outlook continues to call for a building upper-level ridge over the center of the U.S. with surface high-pressure expanding over the lower Mississippi Valley.  That combination should not only lead to drier days by mid-week, but also a warm-up.  In fact, if this scenario pans-out, some WAFB neighborhoods could see a return of the mid-90°s by the middle to end of next week.
So stay dry … and here’s hoping that you get to enjoy the weekend!

Potentially Wet Next Few Days

A passing tropical wave will provide an increase in rain coverage over the next few days.  The threat for tropical development remains low.  The National Hurricane Center currently lists a 10% chance for development.  The wave will continue to move to the west bringing sct'd to numerous showers and t-storms into Southeast Louisiana. 

Today should be a touch wetter than yesterday, but we will remain somewhat on the drier side of the system.  As the wave moves west of South Louisiana, we will move under the wetter side of the system bringing higher rain coverage to the Saturday and potentially Sunday forecast.  Neither day should be a complete wash out, but if you have outdoor plans it would do you well to have an indoor option.  Thanks to the clouds and rain, high temperatures should remain in the upper 80°s to low 90°s.

High pressure will slowly begin to work into the area behind the passed wave.  Monday will continue the trend of sct'd showers and t-storms.  Most of the activity Monday will stay confined to the afternoon hours.  We finally begin to dry out as we move into the middle of the week.  High pressure will limit rain coverage, but it won't create a completely dry forecast.

Rain coverage Tuesday will be 30% with just a 20% coverage Wednesday and Thursday.  The lower rain chances and increased sunshine will help allow daytime highs to climb into the mid 90°s beginning Wednesday.  Morning lows will stay in the low to mid 70°s.

Thursday, August 22, 2013

Sct'd T-Storms into the Weekend

By Jay Grymes & Steve Caparotta

To put it simply: our thinking hasn’t changed for the coming days in terms of the forecast.  Surface high pressure to our east will help maintain a steady flow off the Gulf through the weekend.  To our west and northwest, a building upper-level ridge may become a more dominant player for our weather, especially by next week.
Don’t be looking for any relief from the heat and humidity through the coming 7 days or so.  While a “backdoor” cool front will approach our area from the northeast over the weekend, the current thinking is that the front stalls and fizzles out over Mississippi.
That means our current August weather continues -- expect more of the same.
Morning lows will run in the low to mid 70°s for metro Baton Rouge, with occasional morning showers closer to the coast.  Don’t be surprised to see some patchy sunrise fog, but not so much as to be a problem for the morning commute.  Afternoon temps will rise into the 90°s for most WAFB neighborhoods just about every day, and that daytime heating will combine with the moist-and-unstable Gulf air to fuel scattered afternoon and early evening showers and t-storms.  For many communities, much as we’ve seen over the past several days, early afternoon 90°s will drop into the 80°s -- possibly even the 70°s -- later in the day thanks to the clouds and showers.  We’re setting daily rain chances in the 30% to 40% range through the weekend and into next week.
There are some hints that we could see a modest dip in those rainfall probabilities by the middle of next week as an upper-level ridge expands over the central U.S. -- while at the same time, weak surface high pressure tries to take hold over the Gulf Coast states.  We’ll have to watch to see how all this plays out, but should that combination of features come to pass, we could see a notable warm-up by the middle to end of next week.
As for the tropics, all remains relatively quiet over the Atlantic Basin, especially give that we are in late August.
A modest tropical wave (easterly wave) located over the northeastern Gulf may add a bit to our Friday rain chances but its impact will mainly be limited to the coastal parishes.  The National Hurricane Center is currently giving the wave only a 10% chance of development in the coming days as it moves from east to west across the northern Gulf.  Farther to the south and southeast, a broad disturbance continues to move across the west-central Caribbean and appears headed for the southern Gulf in the coming days.
While there is nothing to suggest a quick spin-up of either of these features right now and there is no cause for concern at this time, both are deserve watching.  Let’s face it, (1) it is late August and (2) the Gulf and Caribbean waters are plenty warm.
Over the open tropical Atlantic, dry air and unusually-persistent stability (for this time of year) have put the clamps on eastern Atlantic wave development.  What’s more, most of the guidance suggests that this pattern will continue for the next several days, at least.  Could we get through the month of August without a hurricane?  Uncommon, but not unheard of.  A quick scan of the record books suggests that the last hurricane-free August was back in 2002; what’s more, hurricane-free Augusts have occurred a handful of times over the past 50 years.
So maybe you’re thinking, “What happened during the 2002 season?”  12 ‘named’ storms by season’s end, including 4 that visited Louisiana: Bertha, Hanna, memorable Isidore and even-memorable Lili!  In fact, the 4 Louisiana ‘hits’ in 2002 are the most for any season on record for the Bayou State!

Wednesday, August 21, 2013

Typical Summertime T-Storms Persist

By Jay Grymes & Steve Caparotta

For the trivia buffs ... note that today’s “Normal Low” is 73°, the first 73° normal low since July 2nd.  “Climatologically,” we’ve arrived at the time of year when we begin the slow cool down into autumn.  (But don’t start cheering just yet -- it’s not likely to feel noticeably cooler for a another several weeks!)
As expected, scattered showers and t-storms developed over the WAFB viewing area this afternoon ... and you’ll want to keep the umbrella nearby for the next several days.  We still anticipate mainly-afternoon scattered showers and storms for Thursday, Friday and the weekend.  Our “normal” August weather pattern looks to be locked-in right into next week:  daytime heating will enhance afternoon instability and take advantage of abundant Gulf moisture to get things going each afternoon.
The quasi-stationary front that has been plaguing much of the Southeast U.S. with daily rains appears to be finally fizzling out, but it likely gets replaced by sea-breeze set-ups each day that will fuel daily scattered rains through the weekend and into next week.
Our forecast through the coming days calls for morning minimums in the low to mid 70°s for metro Baton Rouge.  During the afternoons, temps will reach the 90°s for most WAFB neighborhoods before the rains arrive.  As is typical for summer, we don’t anticipate any severe-weather outbreaks in the coming days but one or two storms could be on the strong side.

We’re expecting rain chances to run in the 30% to 40% range through the weekend.
Remember, this percentage represents the amount of the WAFB area expected to receive “measureable” rainfall (meaning rains of 0.01” or more) each day.  In other words, not everyone gets wet every day.  In fact, there is a chance -- albeit a slight chance -- that a couple of WAFB areas could remain essentially rain-free right through the weekend.  But over the course of the next four days (Thursday thru Sunday), simple statistics tell us that there is a very good chance -- better than an 80% chance -- that you’ll see at least some rain.
Also, remember that the rain forecast "percentage” does not tell us “how much rain?”  True, in the summer, higher rain chances are often associated with more active weather and can result in larger daily totals, but there are no guarantees.  The truth is, forecasting rain amounts during the “summer shower season” is much more difficult than trying to predict storm totals during the cooler months when most of our rain is frontal.
No better example of that then what we’ve seen the past couple of days:  many of us have had only modest amounts of rain so far this week, yet some communities experienced localized downpours of 1” to 3” in short periods of time!  Yep, say “hello!” to summer weather in the Bayou State!
In the meantime, while we dodge the afternoon rains, let’s enjoy the “quiet” time in the tropics.  Although we are watching a few tropical waves in the basin, none are currently showing any imminent threats for development.

Tuesday, August 20, 2013

Sct'd T-Storms Again on Wednesday

By Jay Grymes & Steve Caparotta

The same quasi-stationary front continues to linger over the Southeast U.S., providing a weak focus for afternoon showers and storms from the Carolinas to near Lake Pontchartrain.  What’s more, the remnants of the persistent boundary are likely to linger into Thursday or Friday, helping to fuel scattered rains and occasional t-storms through the rest of the week.
We’re going with morning lows in the low to mid 70°s, afternoon highs in the low 90°s, and scattered afternoon showers and t-storms right through the weekend and into next week.  But keep in mind that is just about “normal” for late August.
A weak easterly wave over the east-central Gulf may add to the afternoon instability just a tad for Wednesday afternoon, so we’ll post rain chances at 40% to 50% for tomorrow.   (By the way, why do we call them “easterly” waves?  Because they move in the low-latitude tropical flow -- generally from east-to-west.  The naming convention is similar to the way we label winds:  a north wind COMES from the north and GOES toward the south.)
Rain chances for the rest of the week will remain in the “scattered” category each afternoon, generally around 30% to 40%.  A few morning showers can’t be ruled out each day, but morning rains will mainly be confined to the coastal parishes.
In the extended outlook, the NWS is hinting that a “backdoor” cool front may try to slip into south Louisiana late Monday or early Tuesday,  but even if that does occur it will have little impact on our local August weather.  (Most of our cold fronts arrive from the west and northwest.  By “backdoor,” we mean a front that approaches the region from the northeast.)
Elsewhere in the tropics ... well, simply nada, at least for the time being!  We’re spying a couple of tropical waves over the Atlantic basin, but none are showing any potential for development at this time.  So let’s enjoy the “quiet” in the tropics while it lasts, since it is a sure bet that the “quiet” is temporary!

Monday, August 19, 2013

Back to "Typical" August Weather

-- Jay Grymes / WAFB Storm Team 
For most of us, it was a fairly nice weekend .. although I did get a good shower in the middle of grass-cutting on Saturday afternoon! Add to that the fact that the disturbance in the Gulf simply fizzled away and you could hardly complain about the past couple of days. Even with the clouds, today was a fairly nice day by August standards with dew points in the low 70°s.
The weak quasi-stationary front that was meandering along the Louisiana coast last week and through the past weekend still lingers, although most of the “energy” associated with the boundary is located far to our east. It will provide a little lift for local showers on Tuesday and for each of the next few days, as the NWS Weather Prediction Center has the front remaining on their forecast maps into Friday. In fact, while the stalled front won’t be a real problem for us, parts of the Southeast U.S. could be dealing with serious flood threats by mid-week.
For us? Let’s call it a 30% rain chance for Tuesday and set rain chances at about 30% to 40% for the rest of the work week across metro Baton Rouge. Highs each day will run in the 90° to 92° for the Red Stick with morning lows generally in the low 70°s. All in all, just about “normal” for mid to late August.
Unlike the past several days, the 7-day outlook shows no signs of another cool front headed our way. So “near normal” is a good bet through the weekend as well.
We’ve already mentioned the demise of the Gulf disturbance (92L) and the weekend also saw an end to Erin, an open Atlantic storm that moved north and lost ‘her’ tropical character on Sunday. Elsewhere in the Atlantic Basin, there’s just not much to talk about. Although there are a couple of tropical waves evident in the satellite imagery, the National Hurricane Center currently has no areas in the basin under “watch.”
So let’s enjoy the quiet while we have it ... the climatological peak of the hurricane season -- roughly around September 10 -- is not that far down on the calendar!

Friday, August 16, 2013

Weekend Weather Hinges on Gulf Disturbance

By Jay Grymes & Steve Caparotta

Not a bad day today and we think Saturday shapes up to be much the same.  Admittedly, most of us missed out on the upper 60°s we forecasted for this morning’s start -- the air just didn’t get quite as cool and dry overnight as we had expected.  Still, most saw wake-up temps near 70° with Friday afternoon highs around 90°. 
A weak, meandering front continues to linger along the Louisiana coast.  It provided just enough lift to fire off a few showers and a couple of t-storms this afternoon and we can expect the same for Saturday.

Saturday will start off with fair to partly cloudy skies and sunrise temps in the upper 60°s to around 70° for metro Baton Rouge.  And like Friday afternoon, Saturday afternoon will be mainly dry with “comfortable” dew points running in the 60°s under partly cloudy skies and highs topping out around 90°.  No complaints for mid-August weather here along the Gulf Coast.
For now, we are going with scattered, mainly-afternoon showers and a few t-storms for Sunday, with scattered rains for Monday and Tuesday.  However, we admit to limited confidence in the Sunday-through-Tuesday forecast as the outlook for those days is largely dependent upon developments over the western Gulf.
Okay, so what about the low in the Gulf?
With some of the mid-day model updates available, the “smart money” goes for landfall along the TX coast in three days or so possibly as a low-end tropical storm (T.S. Fernand).  However, we still don’t have anything even close to a consolidated system as yet.   While there is a low-level spin evident to the west of the Yucatan, any significant convection is currently 100-150 miles or more to the ENE of that surface spin.  A look at the satellite loops confirms that the low-level spin is west of the Yucatan while the convection is north of the peninsula.

The convection (t-storm activity) to the ENE of the surface low is associated with an upper-level low -- arguably a potential nemesis for a tropical system in its pre-depression stage, especially when positioned to the east or NE of the low-level spin.  Now, if the convection can link up with the low-level spin without destroying it, then maybe something starts to organize over the weekend.  But we don’t see the convection merging up with the spin very quickly … nor do we expect the low-level spin to move much in the next day or two.
So, a ton of uncertainty remains.  One possibility, although not high on the list of real options, is that we get a surface center re-location, or more likely, a new low-level spin develops closer to the present convection envelope.   Another possibility: the upper-low disrupts the surface spin and 92L heads to the history books.
Could Louisiana still see a tropical storm landfall out of all of this?  For now, we’re saying that chances are well below 1-in-5 that 92L becomes Fernand and heads our way.  The latest run of our in-house 'Precisioncast' (RPM) does bring some part of the system toward the Louisiana coast on Sunday. IF that were to happen, Sunday would be quite a bit wetter than currently indicated in our forecast, but we don't expect winds or surge to be much of an issue.

Elsewhere in the tropics, the National Hurricane Center is still tracking Erin, now downgraded to a tropical depression (TD).  The official forecast keeps Erin at TD strength through the coming days but it is looking less likely that Erin will be a threat to the U.S., the Bahamas or the Caribbean.  Even if Erin maintains ‘her’ tropical characteristics through the coming week, the extended-range outlooks suggest that ‘she’ will start hooking to the north and remain over open water.

Thursday, August 15, 2013

Nice Days Ahead...Keeping An Eye on the Gulf

By Jay Grymes & Steve Caparotta

Not a bad day at all for the middle of August!  And Friday may be just a little bit better, with a little more sunshine and an additional drop (albeit slight) in the afternoon humidity.  Too much of this nice weather could spoil us for the summer ... but not to worry, as traditional summer weather will return soon enough.

Uncertainty in our local forecast for the coming days centers on the disturbed tropical weather currently over the Yucatan Peninsula.  The poorly defined tropical wave -- still tagged as ‘92L’ -- has yet to show signs of organization today and has no clear-cut center of low pressure.  In addition, the time it spends over land today and tonight will do little to help us figure out just what it is going to do or when it will finally move back over water.

Add flip-flopping models to the confusion and you can see how we have little forecast confidence in terms of direction or intensity.  In fact, some of the guidance suggests that 92L will barely survive the time over land and will all but break-up before making it back over water.

If 92L survives the overland trip, “where” it emerges from the Yucatan may be just about as important as “when.”  Movement to the northwest today would bring it out into the “open” southern Gulf; a continued westerly path would mean hitting the Bay of Campeche.  A path into the Bay would strongly support a more western track down the road, at least in the shorter term.

However, if 92L heads along a more northwesterly or northerly track today and tonight and enters the open Gulf, then the threat for a central Gulf Coast arrival over the weekend becomes a real possibility.

Hence our local weekend forecast dilemma. 

In either case, Saturday should be another fairly comfortable mid-August day for most of us.  By Sunday, we’ll start returning to something a little more typical for August in the Pelican State.  But if 92L decides to head to the Gulf Coast, it could arrive over the weekend, prompting a series of forecasting adjustments.

Stay with us over the coming days as we try and get a handle on this confounding tropical mess!

Wednesday, August 14, 2013

Watching the Tropics...

By Jay Grymes & Steve Caparotta

A cool front continues to sag slowly southward through the Bayou State.  The storms earlier in the day were the product of a pre-frontal line that has since moved out over the Gulf waters.

Those mid-day showers and storms took much of the storm energy out of the atmosphere over metro Baton Rouge.  While we are likely done with any strong storms for the day, scattered showers and a few t-storms can be expected through the late afternoon and evening as the front continues is southward drift.

The rains should taper off through the evening and overnight as drier air filters in from the north behind the cool front.  Most WAFB neighborhoods -- especially those along and north of the I-10/12 corridor -- can expect fair skies for Thursday’s wake-up.  In fact, WAFB’s northern viewers are likely to wake to temps in the 60°s!  We could still see a few showers along the coast, where the weak front will be positioned, but even there, rains are likely to be isolated and light in nature.

The front is likely to stall near the coast and meander a bit from Thursday afternoon into Saturday morning.  For most of us, that means a run of mainly fair skies, little rain, and less-humid conditions.  While baton Rouge afternoon highs will still get up around 90° to 92° for Thursday, Friday and Saturday, the lower dew points will mean less-oppressive afternoon heat and morning starts in the upper 60°s to around 70° for many -- not bad at all for mid-August!

But the drier air doesn’t last long.  By Sunday, the quasi-stationary front will have fizzled out, allowing for Gulf humidity to creep back into south Louisiana.

However, the bigger developing story is the outlook for the tropical disturbance in the western Caribbean -- currently labeled as ‘92L.’  The mass of clouds and convection in the western Caribbean has displayed slow consolidation through the day but a clear low-level center has yet to emerge.  The latest model consensus brings the ‘proposed’ center over the Yucatan tomorrow, with it moving into the Gulf of Mexico by Friday.

After that, all bets are off.  Until we have a defined center and sense of the system’s intensity, there will remain a number of possible scenarios that could play out.  Currently, some of the model runs take a developing system to the northwest into Mexico or Texas.  At the same time, a number of other models, including the American GFS, bring the system into the central Gulf Coast states over the weekend.

As if that isn’t confusing enough, the intensity forecasts are even more divided.  While the consensus keeps the system below hurricane strength (at least for now), there is no clear sense of just how well developed the system might become.  Most of the early forecast runs show peak intensities varying across the range of tropical-storm-force winds.  But remember, the forecast skill for intensity is only slightly better than “no skill at all” -- in other words, we are completely unclear as to what this system will do over the next three days.

The bottom line: this is one to keep tabs on.  No need to get overly concerned just yet, but be aware that this could become of threat for the Bayou State.  And if that does occur, it is most likely to arrive over the weekend.  Stay tuned!

Tuesday, August 13, 2013

Rains Continue into Wednesday

By Jay Grymes & Steve Caparotta

It was a wet day for most WAFB neighborhoods today and it is looking like an even wetter day for Wednesday.
In fact, a line of storms along the LA/MS state line this afternoon has prompted at least two Severe T-Storm Warnings.
That line of storms will continue to move to the south and southeast this evening at about 10-15 mph, but we think that it will lose some of its energy as we head deeper into the evening hours.  We don’t expect to be dealing with a ‘severe’ threat tonight, but plan on scattered showers and even a few rumbles of thunder overnight and into the morning commute on Wednesday.  We’re calling for an early morning low of around 75° for the Red Stick on Wednesday.
As we mentioned, rain coverage should be even more widespread for Wednesday -- we’re calling for a 60% to 70% rain chance through the day ... and that might be on the conservative side of things.  Some WAFB neighborhoods could get up to around 90° for a high on Wednesday but many will stay in the 80°s thanks to the clouds and rain.  A few neighborhoods could see some brief, heavy downpours through the day, too.

A cool front currently to our north will continue to sag to the south in the coming days.  We expect the front to reach the coastal parishes by Thursday morning, putting much of the WAFB viewing area on the north side of the front during the day.  We’re going with scattered rains early on Thursday for metro Baton Rouge, with only isolated rains later in the day.
The frontal advance should deliver a slight cool-down with a nice dip in the humidity.  In fact, we’re calling for morning lows in the 60°s for many WAFB communities by Friday morning.  (The last time Metro Airport recorded a low in the 60°s was July 26.)
The big question becomes, “Just how far south will the front get?”  Our in-house PrecisionCast model pushes the front all the way out and over the northern Gulf, which would mean mainly-dry weather for Friday and Saturday.  Our hunch is that the model may be just a little over-aggressive – don’t be surprised to see the front stall closer to the coast.  Under that scenario, we’ll keep slight rain chances in the outlook for Friday and Saturday, but only in the “20% or less range.”

The front likely fizzles out on Sunday, allowing for a slow-but-steady return of Gulf humidity as we head into the early part of the work week.

In the tropics, we have a new “Invest” -- 92L -- in the west-central Caribbean as of this afternoon.  It’s the same area of disturbed weather we’ve been watching for the past couple of days.  92L certainly doesn’t look very organized at this stage and any development will likely be somewhat slow as it moves to the WNW.  We are awaiting some new computer model runs -- the current guidance is rather mixed on not only where 92L goes but also how well-developed it might become.  Stay tuned!

Monday, August 12, 2013

Good Rain Chances Continue This Week

By Jay Grymes & Steve Caparotta

The “wetter” pattern that began last week is expected to continue through Thursday.  In fact, afternoon showers and occasional storms may be a bit more widespread over the coming days, so keep the umbrella handy.

We’ve had a couple of reports of stronger storms with locally-heavy rains, gusty winds, and frequent lightning strikes today.  None of the storms reached “severe” criteria, but a handful were quite strong nonetheless.  Isolated strong t-storms can be expected for each of the next three days, so keep alert if the skies grow dark during the afternoons.

We’re setting rain chances at 50% for Tuesday, and at 50% to 60% for Wednesday and Thursday.  Morning lows for the Capitol City will be in the mid 70°s for the next three days, with highs hitting the low 90°s for most WAFB neighborhoods before the afternoon rains arrive.

The outlook for the end of the week currently calls for rain chances at around 30% for Friday, Saturday and Sunday.

A cool front currently extending from the Great Lakes into the Central Plains is expected to continue to slowly work its way southward over the coming days, reaching the WAFB viewing area by Thursday.  The current thinking is that the front will slowly sag into the coastal waters by Friday then linger along the coast or possibly meander over the coastal parishes into the weekend.  With the front nearby, we can’t expect rain-free days, but as long as the front is positioned to the south of most WAFB communities, many of us will get a limited amount of relief from the summer heat and humidity.

That break will likely be rather short-lived, unfortunately, as the front will be dissolving over the region by Sunday, allowing a full return of Gulf humidity.

However ... our current weekend outlook is subject to change depending on what plays out in the tropics over the coming days.

A broad area of disturbed weather currently over the central Caribbean could produce a marked change in our weekend outlook, depending on what becomes of that tropical mess.  Currently, the National Hurricane Center (NHC) appears rather unimpressed by the tropical wave, giving it only a 20% chance for development over the next five days.

We are a little surprised at this low-end estimate for development over the coming 5-day window as multiple models appear to be much more aggressive with the future of this tropical wave.  And more importantly, more than one model brings a developing system into the Gulf over the coming days.  Were that scenario to play out, we could be watching a tropical storm (or possibly a low end hurricane) taking aim at the U.S. Gulf Coast by the end of the week -- stay tuned.

Friday, August 9, 2013

Sct'd T-Storms Persist into the Weekend

By Jay Grymes & Steve Caparotta

As expected, the upper-level ridge that has been the driver in our run of dry, mid-90° days has continued to weaken and shrink, being squeezed on the south side by a west-bound tropical wave crossing the Gulf and on the north by a moderately-well developed upper-level trough.
Scattered rains extended over the viewing area today, with rains being a bit more numerous closer to the coast.  The combination of the weakened ridging, the Gulf wave and an increase in atmospheric moisture over the region prompted today’s rains ... and we’re keeping rain chances in the “scattered” category for WAFB neighborhoods through the weekend.

Of course, another advantage of the rain -- which typically means more cloud cover -- is a dip in the daytime highs.  That’s why, like today, we anticipate highs for Saturday and Sunday to top-out in the low 90°s.  Yep -- still summer-like for South Louisiana, but at least a little cooler than what we experienced through the first 8 days of August.

Plan on morning starts for Saturday and Sunday in the mid 70°s for the BR metro area ... and as usual, a little warmer closer to the coast and a tad cooler near the state line.  Mornings will be dry for most, but those closer to the coast should expect a few AM showers.  By the afternoon for both days, our moist-and-unstable summer air mass will get a sufficient boost from daytime heating to kick-off afternoon showers and t-storms.

We aren’t anticipating all-day rains for either weekend day and no severe weather outbreaks.  In fact, not everybody in the viewing area gets “wet” this weekend -- but between the two days, most WAFB communities can expect at least some rain.  Guidance from the NWS Weather Prediction Center indicates that most WAFB viewers should plan on around 0.25” to 0.75” of rain over the weekend, with localized totals of 1.0” or more where slow-moving storms produce heavier downpours.

We can use the rain.  Most of the viewing area has been quite dry over the past couple of weeks.  In fact, Doppler radar estimates suggest that many sections of the WAFB region, especially areas east of the Amite River, are running roughly 50% to 75% of normal for rainfall for the past 30 days.  That’s not yet “drought” conditions but most of us won’t complain about a good soaking.  In fact, even with our forecast for “scattered rains” this weekend, anything less than a half-inch will only provide brief, limited relief from the hear -- at this time of year, evaporation rates typically run around a quarter-inch per day.

We’re getting some mixed signals about an approaching cool front towards the middle of next week.  Could it make it this far south and provide some real relief from the heat?  Well, it is possible, but don’t count on it.  For now, we’ll go with a forecast that stalls either over us or just to our north.  That means plan on staying warm and humid  with “scattered” rains just about every day through the upcoming work week.

Still “quiet” in the tropics ... and likely to remain so well into next week at least.  But remember, the peak of the season (roughly September 10th) is not far off -- are you ready?

In the meantime ... try to stay cool and enjoy the weekend!

Thursday, August 8, 2013

Better Rain Chances into the Weekend

By Jay Grymes & Steve Caparotta

Another HEAT ADVISORY was issued for the WAFB viewing area today as Heat Index readings reached the triple digits as early as 10AM for some neighborhoods.  That ADVISORY will be allowed to expire at 7PM this evening ... and the outlook for the next few days suggests a break from the mid 90°s for most of us.

In fact, you may even need that umbrella over the next few days as we return to a pattern of “scattered” afternoon and early evening rains for Friday and the weekend.

The upper-level ridge that has kept us so hot and mainly-dry for the last several days will finally weaken enough to allow our warm-and-moist summer air to do it’s normal “thing” -- generate those afternoon thundershowers.  We’re going with a 50% rain chance for Friday and keeping rain probabilities around 40% or so for both Saturday and Sunday.  These won’t be all-day rains, and the action probably won’t really get going until the afternoon hours, so many of us will still see afternoon readings in the low 90°s.  But the clouds and rains should mean an end to the mid 90°s, at least until sometime next week.

Daytime heating, a return to a more southerly flow and seabreeze pattern, plus a weak “easterly wave”  in the southern Gulf (tropical disturbance traveling from east-to-west) will all combine to add a little boost to those afternoon rain chances, especially for Friday.

Rain projections from the NWS Weather Prediction Center (WPC) suggest that most neighborhoods can expect from one-half inch to better than one inch of rain between now and Sunday evening, with a few pockets running upwards to near two inches (where localized downpours occur).  All in all, that’s good news for most communities, especially given the hot-and-dry weather of late.  The experts say that there is “no drought” for our viewing area -- at least not yet -- but we note that more and more folks are turning on the sprinklers and irrigators for the lawns and gardens.

In other weather news, while the tropics remain relatively quiet, the NOAA Hurricane Experts issued their early-August update for the 2013 season.  With four named storms already, they barely adjusted their forecast from late May -- tweaking it downward ever so slightly.  Their official forecast now calls for a 70% chance of 13-19 ‘named’ storms for the season (down from May’s call for 13-20), of which 6-9 will become hurricanes (down from 7-11).

Wednesday, August 7, 2013

A Break from the mid 90°s?
The HEAT ADVISORY that has been in effect since Tuesday will be allowed to expire later this evening, but don’t be expecting a quick cool down.
Under fair to partly cloudy skies, we’ll ease down to a Thursday morning low in the mid to upper 70°s for the ‘Red Stick.’ August heat returns for Thursday afternoon with highs climbing back into the mid 90°s for many of us.

But we’ll add in a 20% to maybe 30% rain chance for Thursday afternoon and early evening, providing a little “wet relief” from the heat for at least some WAFB neighborhoods. And the forecast gets “wetter” for Friday and into the weekend -- and a wetter outlook also means a dip in those afternoon highs.

The upper-level ridge that has been the driver behind our run of hot and mainly dry weather is slowly being weakened, with that weakening expected to hold through the weekend. The ridge stays just strong enough to keep us mainly-dry for Thursday -- and let highs reach the mid 90°s for many. But by Friday, the ridge’s influence wanes, allowing for our moist-and-unstable summer air to do its thing. In addition, a weak wave over the Gulf should provide a modest boost, resulting in a return to a somewhat more typical weather pattern with afternoon scattered showers and t-storms for Friday, Saturday and Sunday.
We’ll keep the higher scattered rains in the forecast for the early part of next week as well.
All quiet in the tropics -- no tropical waves are displaying any development potential through the next several days.