Tuesday, May 29, 2012

More Heat & Humidity!

We continue to reach the 90°s for highs, and a second morning with lows in the 70°s for many WAFB neighborhoods is a good reflection of the low-level humidity that has set-up across the viewing area. Yes, hot and humid indeed.

We’re not expecting any significant changes for Wednesday either. Look for sunrise temps in the 70°s for the Capital City with afternoon highs climbing into the low 90°s -- the 11th straight day in the 90°s. We do add a couple of afternoon t-showers to the Wednesday forecast, but we’re going with rain chances at a modest 20%, so most of us stay just hot and dry.

Rain chances go up ever so slightly for Thursday, with better rain chances on Friday. We think we may end our run of 90° days on Thursday or Friday as well. A late-spring cool front will slip into the Bayou State late Thursday in to Friday, prompting us to post a 30% rain chance for Friday. In other words, some of us get rain, but unfortunately many of us will stay essentially rain-free through the coming days. And to be honest, even for those that do get rain over the next three days probably won’t get what they would like: right now the NWS Hydrometeorological Prediction Center has most of the WAFB region getting less than one-half-inch of rain between now and the weekend.

Yep -- with our two-week run of dry and warmer-than-normal weather, we seem to be easing back towards near-drought conditions.

There is one piece of good news: Friday’s cool front will give us a reasonably good Saturday for outdoor weather. The “drier” air mass behind Friday’s front will mean morning lows on Saturday dipping well into the 60°s and a less-humid afternoon, although it will be warm given the expected clear skies and sunshine. But the spell of low-humidity will be very brief -- in fact, we think it’s gone by Sunday!

Better rain chances are currently posted for the extended outlook on Monday and Tuesday.

And in the tropics, T.D. Beryl continues to display a reasonably good satellite presentation and symmetry, with “productive” rainbands. NWS Doppler radar estimates show that Beryl may have dumped more than 10” of rain over a section of northern Florida and as much as 6” to 8” over parts of extreme SE Georgia, but thus far, the rains do not appear to be generating widespread flooding. Beryl is moving to the northeast and is expected to continue along this track across eastern Georgia than along the Carolina coasts and emerge in the Atlantic, where ‘she’ could regain tropical-storm strength before reaching the cooler Atlantic waters and losing ‘her’ tropical characteristics.

Thursday, May 24, 2012

By Jay Grymes & Steve Caparotta

There are three weather stories to discuss as we head towards the extended Memorial Day weekend.

The first is the local forecast for summer-like heat. The upper-level ridge of high pressure that has kept northern Mexico and much of Texas hot and mainly-dry for the last couple of days continues to expand and shift towards the lower Mississippi Valley. As you recall, upper-air ridging typically puts a clamp on cloud development -- not only means little or no afternoon showers activity but also allowing more sunshine to add to the daytime heating. Plus, ridging aloft further adds to the warmth because it generates sinking air, and sinking air must warm as it descends.

The bottom line: it’s going to be HOT! So, for how long? We expect ridging to dominate the Bayou State weather through Monday, at least. This is good news for many, as it means dry days for the long weekend and the “unofficial” start of summer. For a few others, however, “hot and dry” means time to start thinking about watering the gardens and landscaping.

Don’t be surprised to see some mid 90°s around the region and posted by our WAFB Weather Watchers between Saturday and Monday! But you’ll notice we keep the low 90°s in play through the entire 7-day outlook. We’ll add in slight mainly-afternoon rain chances towards the latter part of next week, but nothing to warrant a heat-breaking trend anytime soon!

The other two weather stories deal with the tropics.

The NOAA hurricane specialists have issued their 2012 Hurricane Outlook today, calling for 9-15 ‘named storms,’ with 4-8 of those becoming hurricanes and from 1-3 of those hurricanes becoming ‘major’ storms. In general, their forecast leans towards something near the long-term norm for the Atlantic Basin ... not surprising and not too different from the general forecasts we’ve shown for several other hurricane prognosticator teams. Note that this forecast calls for activity far below what we saw in 201 and 2011, when both seasons tallied 19 ‘named storms.’

Our interest has returned to the tropical satellite loops this afternoon. Although it is still far too early to call for certain development, the elongated area of low pressure that was in the western Caribbean on Tuesday and Wednesday has moved north and appears to be centered somewhere near the eastern Florida Keys as of this afternoon. With pressures falling and some evidence of broad circulation, the National Hurricane Center has upped the chance for development to about 4-in-10 over the next two days. The most likely region for the low to develop would be over the warm Gulf Stream waters somewhere east of Florida and north or northwest of the Bahamas.

Under typical circumstances for May, a tropical system off the Florida Atlantic Coast would be no big deal for interests along the central Gulf Coast. But there is one ‘hook’ this go around: the upper-level ridge that is going to heat us up over the coming days is expected to continue to shift eastward over the long weekend. If it gets positioned to the north of this western Atlantic low, it could cause the system to stall and begin a westward track. Indeed, that is what the NWS extended surface outlook is suggesting, with the low moving into the northeastern Gulf and possibly into the Florida Panhandle by Monday or Tuesday.

There are a stack of “ifs” tied to this extended tropical outlook, but this Florida low certainly bears watching in the coming days, especially if you are headed to Florida for the long weekend!

If you're staying around BR, maybe you're headed to the Bayou Country Superfest!  Great music .. but HOT!  Be prepared for the sunshine and prolonged heat!

Wednesday, May 23, 2012

More & More Heat!

By Jay Grymes & Steve Caparotta

We’ll keep an eye on the AQI through the afternoon and evening, as DEQ has issued an Ozone Alert for Wednesday -- the second consecutive Ozone Action Day for metro Baton Rouge.  The preliminary data suggest that the metro area missed reaching Code “Orange” on Tuesday … and with luck, the same will be true for Wednesday afternoon.
While storms were fairly isolated today, there were a couple of reports of severe weather. Seven to eight homes received minor damage in Arabi (St. Bernard Parish) from storms this afternoon, including one home having its carport destroyed. Also, a funnel cloud was spotted over the south end of Lake Pontchartrain near Metairie.

But there is no missing the heat!  As hot as it feels, let’s understand that our recent run of 90° days  is not way out of the norm for this time of year!  History shows us that daily norms for mid to late May are in the upper 80°s, so running a couple of degrees above that is certainly not all that far from the norm.  However, the persistence of warmer-than-normal weather -- which has been the rule for 2012 thus far -- is certainly noteworthy.  In addition, recent long-range outlooks are calling for better-than-average chances for continued warmer-than-normal weather in the coming weeks.  Bottom line: here’s hoping that the A/C has been serviced and is working well because you’re certainly going to need it!
Over the coming days, we can’t completely rule out the chance of a stray afternoon shower or two, but the weather headline through the rest of the work week and into the coming Memorial Day weekend should read: “Staying mainly hot and dry!” ... or maybe, more simply: “More of the same!”
Not only do we stay in the 90°s for afternoon highs, but the morning lows will slowly creep up to around 70° by the weekend, a reflection of a continued increase in low-level humidity. 
So it’s hot and mostly dry through Sunday, but we’ll bring a slight chance of rain into the Monday through Wednesday outlook, with roughly a 20% chance of afternoon t-showers each of those three days.  Yet, even with the afternoon rains, we’ll still call for highs in the 90°s all three days.

Tuesday, May 22, 2012

More Heat!

By Jay Grymes & Steve Caparotta

DEQ issued an “Ozone Action Day” for today, but it looks like ozone levels on Tuesday may peak-out below the “Code Orange” criterion.  Unfortunately, the forecast for Wednesday is also a Code “Orange” forecast, prompting another “Ozone Action Day.”  Let’s hope that this does not become a persistent pattern for the summer of 2012!  Elevated concentrations of low-level ozone are potentially problematic (“unhealthy”) for sensitive individuals: mainly the very young, the elderly, and those already afflicted with respiratory problems.  If you or a family member or friend fall within one of these categories, we encourage sufferers to limit their time outdoors, especially during the middle and late afternoon on Wednesday.

In the tropics, Alberto succumbed to the stresses of wind shear and dry air and was formally downgraded from a tropical depression to a post-tropical low during Tuesday morning, with what’s left of Alberto soon to be absorbed by a mid-latitude system. 
As a side note, the NOAA/National Hurricane Center will be issuing their official tropical outlook for the 2012 season on Thursday.  A consensus “average” of more than a half-dozen pre-season forecasts currently available from various university-based and consulting meteorological groups calls for something on the order of 10-12 ‘named’ storms this season.  That’s below the ‘average for 1995-2010, and well below the 19 ‘named storms’ recorded in both 2010 and 2011.
As for our local weather, you’ve surely noted the heat this week.  And yes, more of the same is on the way.  At the same time, the humidity will slowly creep upwards, as reflected by morning lows climbing into the low 70°s over the Memorial Day weekend! 
Isolated showers and t-storms began popping up on Titan9 Doppler this afternoon thanks to the daytime heating and the moist-and-unstable air near the surface.  As of 4:00PM, it doesn’t look like the storms will get as energized as some of those we saw on Monday afternoon and evening, but we can’t rule out the possibility of one or two storms getting quite strong.  With the upper-level flow still mainly north-to-south, this is the set-up that can produce some storms with frequent lightning and hail.
All should settle-down soon after sunset, with a relatively quiet night on tap and lows dipping into the mid to upper 60°s by Wednesday’s sunrise.  We’ll allow for a very slight chance of a shower or two on Wednesday afternoon, but the day looks to be mainly dry and downright hot with highs in the low 90°s for many WAFB neighborhoods.
Hot, humid and mainly dry -- that’s the forecast for Thursday through Sunday, with morning lows in the upper 60°s to near 70° and highs in the low 90°s.  Into the extended outlook, we’ll bring a 20% rain chance into Monday’s (Memorial Day’s) forecast with a 20% to 30% chance for Tuesday.

Monday, May 21, 2012

Few Showers, Staying Warm

By Jay Grymes & Steve Caparotta

Hot enough for you? Today's high temperature of 92° in Baton Rouge matches our hottest day so far this year. We also hit a high of 92° on May 6.

A weak front will sag into the viewing area this evening and then linger as a stationary front into Wednesday before retreating northward and dissipating.  While the lower and middle levels of the atmosphere are sufficiently unstable to fuel a few t-storms this afternoon and evening, this front will not provide enough lift to get widespread rains going.

After Tuesday, high pressure will once again take charge of our regional weather, and that means hot and mainly-dry days ahead.  In fact, while a stray shower here or there is possible through the work week, most neighborhoods will remain rain-free into the Memorial Day weekend.

We’ll have one fairly comfortable morning on Wednesday, but after that the humidity will add to the daytime heat and make it feel like summer!  We’re expecting morning lows in the upper 60°s to low 70°s from Thursday through Monday, with most neighborhoods reaching 90° or more on Wednesday and right through the “long” three-day weekend ahead!

In the expected, we’re bringing a slight chance of rain -- at 20% -- into Monday afternoon’s outlook.  So the “unofficial” start to the summer will be hot and mostly dry, just like the days leading into it!

In the tropics, an “early” ALBERTO continues to hold onto minimal tropical-storm strength: as of 4PM on Monday, ALBERTO continues to display maximum sustained winds near 40 mph.  ALBERTO is moving away from the U.S. Atlantic Coast and is expected to begin moving to the northeast within the next day.  In addition, the environment around ALBERTO continues to become more hostile for the tropical system.  Dry air is wrapping into the compact storm, mid- and upper-level shear are expected to increase over the system, and the forecast track will take ALBERTO over cooler waters in the coming days.  The way things look right now, ALBERTO probably loses his ‘tropical’ characteristics by mid-week.

Friday, May 18, 2012

Hot, Mainly Dry Weekend

By Jay Grymes & Steve Caparotta

Fair and warm for this evening’s “Live After Five” ... temps will stay in the 80°s throughout the 3-hour street party but the humidity remains comfortably low, so it won’t feel bad at all!  Why not get out and enjoy the music downtown, make a run to your favorite restaurant, or just lounge about in the backyard.

Our weekend is shaping up to be very warm and remain dry.  We’re calling for sunrise temps in the mid 60°s for metro BR for both Saturday and Sunday, with highs for both afternoons getting up around the 90° mark -- we won’t be surprised to see a few Weather Watchers report highs in the low 90°s.  So enjoy the weekend, but be careful in the heat -- and don’t forget the sunscreen!
A mid/upper-level ridge remains in control of our regional weather, and that should continue through the weekend.  Remember, high pressure aloft limits the ability for clouds to develop vertically -- and vertical development is a requirement for rain.  By limiting the clouds, ridging also can enhance hours and percentage of sunshine, helping to warm things up.  In addition, high pressure in the middle and upper layers of the atmosphere encourages subsidence: sinking air from above.  And while it may not be completely intuitive at first, sinking air warms very quickly and that can add to the afternoon’s warmth.
The upper ridge may weaken and shift east by Monday into Tuesday, allowing a slight chance of rain for Tuesday into early Wednesday, but the ridge re-asserts itself by late Wednesday into Thursday.  As a result, it looks like we’ll stay warmer than normal not only for the weekend, but for most or all of the coming seven days!

Thursday, May 17, 2012

Summer-like into the Weekend

By Jay Grymes & Steve Caparotta

Thursday was quite the warm day with ample sunshine, but the humidity wasn’t bad at as dewpoints stayed in the 50°s and 60°s.  All in all, it was a rather nice day!  And we expect much the same for Friday, although it may be a degree or two warmer and just a tad more humid by the afternoon. If you plan on heading downtown for Live After Five, it should be dry, but be ready for a warm start!

Our forecast keeps the days mainly dry for both Saturday and Sunday, but a return flow pattern (air coming in from the Gulf) will mean rising humidity levels.  With the added humidity and highs around the 90° mark for both Saturday and Sunday afternoon, both days will feel almost ‘summer-like.’   Expect the Heat Index -- even in the shade -- to reach the mid 90°s for some neighborhoods over the weekend.  And there will be plenty of sunshine to boot, adding to the ‘feels like’ temperature and highlighting the need for sunscreen!

We’ve talked about it through much of the week: ridging in the middle layers of the atmosphere has taken charge of the weather for the Gulf Coast and the southeastern U.S. and will remain in force through the weekend and into Monday.  The broad ridge will reduce cloud development over the next few days, all but squash any rain chances, and even add to the daytime heating as a result of subsidence (sinking air, which quickly warms as it descends towards the ground).

Our current forecast calls for dry weather through Monday, with only a slight chance of rain for Tuesday into Wednesday.  At the same time, the 7-day forecast keeps daytime highs in the upper 80°s to around 90° each day -- warmer than normal through most or all of next week.

So enjoy the weekend, but please take care in the mid-day heat and be cautious about the sun exposure!

And speaking of the sun, parts of 8 U.S. states will get to witness an "annular" solar eclipse on Sunday.

The "ring of fire" name is derived from the fact that at its peak, 94% of the sun will be covered by the moon, resulting in what looks like a "ring of fire" for those able to see the eclipse at its best. The graphic below from NASA shows the areas that will be able to see the "annular" eclipse.

Courtesy: NASA

Unfortunately, the eclipse will begin so close to sunset here in south Louisiana that most of us are unlikely to see much. With a clear unobstructed view to the west, you may briefly catch a partial eclipse before the sun disappears below the horizon.

Wednesday, May 16, 2012

Drying Out, Warming Up

By Jay Grymes & Steve Caparotta

We received a little good news from our friends at DEQ, as today’s metro Baton Rouge air quality appears to be topping out in the “Moderate” range (Code “Yellow”).  Yesterday, DEQ issued an “Ozone Action Day” for today -- maybe today’s combined efforts of everyone in the region to limit the release of ozone-producing compounds worked and helped to minimize the development of ground-level ozone!  In addition, earlier today DEQ was preparing for another “Ozone Action” declaration for Thursday, but as of this afternoon, that has also changed, with Thursday’s AQI forecast now calling for “Moderate” air quality for the region.
Isolated to scattered showers and t-storms did develop over portions of the WAFB viewing area on Wednesday, although Titan9 Doppler returns are clearly showing that most of WAFB neighborhoods were still dry as of 4PM.  The biggest action has been occurring closer to the coast, over and near Terrebonne Parish -- persistent thunderstorms have dumped upwards of as much as 2” to 3” of rain just west of Houma as of 4PM.
Doppler radar estimated rainfall for Wednesday. Upwards of 3 inches of rain was estimated near Houma.
Any additional rains that do develop over our region later today will fizzle out during the evening hours.
After today, the outlook remains mainly-dry through the weekend and into early next week.  Mid/upper-level ridging will take charge of the weather across the Gulf Coast and Southeast U.S., putting clamps on rain chances and aiding daytime heating through Sunday.  Along with the “dry” weather, the return of warmer-than-normal afternoon temperatures will be accompanied by a full-dose of Gulf humidity by week’s end. 
You may have already noticed a “warmer” feel to the air today . . . and our forecast calls for it to get warmer in the coming days, with afternoon highs in the upper 80°s to near 90°.  Factor in dewpoints in the mid to upper 60°s by the weekend and we’re talking Heat Index (‘feels like’) values in the mid 90°s for Saturday and Sunday.  “Mom, is the pool ready?”
We’ll re-introduce slight rain chances early next week -- maybe.
And speaking of rain chances, we wanted to take a moment to clear up the terminology association with rain chances. The National Weather Service actually has a long-ago established list of terms/phrases corresponding to specific rain chances. Unfortunately, even some weathercasters and meteorologists in the media seem to be a bit inconsistent about following this list even though it has long been widely accepted in the meteorology community.

One other important thing to note is that the chance of rain has no relation to the intensity or duration of rainfall. In other words, you can have a day with a low chance of rain, but a slow-moving storm could produce heavy rainfall for a prolonged period of time. 

Tuesday, May 15, 2012

A Few Showers Wednesday

By Jay Grymes & Steve Caparotta

DEQ has issued the first “Ozone Action Day” for the year, with Wednesday afternoon ozone levels around the Baton Rouge metro area potentially becoming problematic (“unhealthy”) for sensitive individuals: mainly the very young, the elderly, and those already afflicted with respiratory problems.  If you or a family member or friend fall within one of these categories, we encourage sufferers to limit their time spent outdoors, especially during the middle and late afternoon on Wednesday.

Yesterday we noted a broad mid-level storm system over west Texas and suggested that it would track southeast and miss the Bayou State.  Today, that system did two unexpected things:  it grew in size and took a little turn onto a more easterly path.  Although the system remains relatively weak today, it does look like it will get close enough to the WAFB viewing area over the course of the next 24 hours or so to sling a few showers our way.
We’ve already seen some showers in western Louisiana this afternoon, and we think that the outer reaches of the complex could deliver a light shower or two to the WAFB region this evening and overnight.
Since we still believe the system’s main energy will move out to the Gulf rather than pass over Louisiana, we don’t anticipate this to be much of a rainmaker.  But the system’s circulation, boosted by Wednesday’s daytime heating and moisture off the Gulf, may be just enough to fuel a few mid-afternoon showers in the area.  We’re going with a 20% to possibly a 30% rain chance for  Wednesday.
Titan9 PrecisionCast projection for 4 p.m. Wednesday showing isolated showers and t-storms around the area.
But as the system moves over the Gulf and out of the picture, mid/upper-level ridging will take charge of the central Gulf Coast’s weather through the remainder of the work week and right through the weekend.  Given that set-up, we expect a mainly-dry and very warm run of days from Thursday through the weekend and into next week.  At the same time, we say goodbye to the relatively “dry” air (dewpoints in 50°s and 60°s) that we’ve enjoyed over the last few days -- we’ll start to feel rising humidity levels on Wednesday with a slow-but-steady increase in low-level moisture right into the weekend.
Highs return to the upper 80°s for Thursday through Sunday, with some locations possibly reaching the 90°s.  Add in the rising humidity, and we’ll get a taste of summer-like heat by the weekend, if not before!

Monday, May 14, 2012

Warming Back Up This Week

By Jay Grymes & Steve Caparotta

We’ve had the pleasure of a couple of nice spring days!  In fact, after a string of days in the 90°s earlier in the month, we’ve had a little run of days with highs coming in below-average!  But how long will it last?

Sorry -- not long.  Tuesday looks like it will be the last day with highs at or below normal, with the upper 80°s returning by mid-week.  As a matter of fact, don’t be surprised to see a couple of locations reaching 90° or above by the weekend.

Since the wet weather exited the region on Saturday, somewhat cooler and drier air has taken up residence along the Gulf Coast -- that turned out to be great news for Mother’s Day!  Unfortunately, the mild temperatures of the last couple of days will give way to mainly-dry but warmer weather as weak upper-level ridging takes control over most of the southern U.S. by mid-week.

Tuesday opens with sunrise temps near 60° for metro Baton Rouge, and like we saw on Monday morning, there may be some patches of fog for the morning commuters.  But generally, we don’t expect any widespread fog issues for the morning drive.  Tuesday afternoon will be partly cloudy and a little warmer than Monday.

And the truth is that we can’t completely rule out a stray shower or two on Tuesday or Wednesday – but we’re posting rain chances for both days at well under 1-in-5 (less than a 20% chance).  Disturbances over western and central Texas continue to track east-southeast across the Lone Star State this afternoon and that will continue into the evening.  One or two of these might hold together and expand just enough as they reach the western Gulf to generate a sprinkle during the next two afternoons in our viewing area. 

The way things look now, by Thursday we’ll take any chance of rain out of the picture for the end of the work week and right through the weekend.  But the warm-up at week’s end will be accompanied by a return of inflow from the Gulf, meaning “heat and humidity.”  Yes, by the weekend, we’ll be back to a summer-like feel to the air.

Friday, May 11, 2012

Flash Flood Watch Continues

By Jay Grymes & Steve Caparotta

Looks like we get a break for the rain this evening:  good news for LSU and Southern baseball as well as a number of high-school graduation exercises!!
Today’s rains finally took the form of a broad wave that moved through the BR metro area mainly during the 11am-3pm window.  Behind that east-bound wave, an area of moderately stable air will mean a reprieve from the rain for most of us through the evening and into the night.
But we anticipate a return of another round of showers and storms for Saturday -- we’re going with a 70% to 80% rain chance for the day, with some locally heavy rain possible through the day.
And Mother’s Day?  Looking much better than it did 24 to 48 hours ago - - our latest guidance now suggests that the main storm energy will exit to the east by late Saturday into early Sunday.  That doesn't mean a totally “dry” Sunday, but we think that the latter half of the day should be mostly dry and more cooperative for the outdoor BBQs or family dinners out!

Rain totals through the weekend - - including today - - still appear to be on the order of 1” to 2” for areas north of the I-10/12 corridor, with some areas getting upwards of 3” north of the interstate.  Totals will likely be greater for many locations south of the interstate corridor, with some 4”+ totals possible, especially over some of the coastal parishes.

Because of today’s developments, the NWS has cancelled the FLASH FLOOD WATCH for areas west of the Atchafalaya Basin, but the concern for heavy rains tomorrow has prompted the NWS to expand the FLASH FLOOD WATCH farther to the east.

The rest of the week looks mainly dry, with a slight chance of afternoon and evening showers at mid-week.  Note also in the extended that the week will see a slow-but-steady warm-up, with a return of the upper 80°s by week’s end.

Thursday, May 10, 2012

Rains Returning

By Jay Grymes & Steve Caparotta

No question -- Thursday was a beauty! And we all know that -- sadly -- all good things must come to an end, but does it have to be so quickly!

We’ll enjoy another nice evening and a comfortably cool night with BR metro area lows dipping to around 60°, but clouds will be on the steady return by Friday morning. The morning commute stays dry, but isolated to scattered rains will start popping up around the viewing area by the afternoon. Not everyone gets wet during the afternoon and evening, as we set rain chances in the 30% to 40% range for your backyard, but you might be dodging a shower or two if you’re out and about for Friday evening fun.

During this evening’s weathercasts, we’ll show you a large area of rain currently stretched across portions of the Lone Star State. That mess is headed our way and looks to make for a wet Saturday across the WAFB viewing area. The weekend rains will be the product of the combination of surface low pressure over south Texas moving to the western Gulf, an upper-level low adding to the storm energy, and a cool front sagging into the region from the northwest.

Given this set-up, the main question becomes: how long will this mess hang around?

Models continue to differ a bit on the west-to-east speed of this wet mess, but the complex is shaping up to be a relatively slow-mover. That means not only a “wet” Saturday but rains are expected to extend into Mother’s Day as well. We’re going with a 70% rain chance for Saturday and continuing with a 50-50 chance for Sunday. The one hope is that the system moves along quickly enough to allow for a bit of a dry-out during the latter half of Sunday.

And what about rain totals?

Given the system’s relatively slow advance and the availability of Gulf moisture throughout its west-to-east trek, we could be looking at some fairly decent rain accumulations, especially along the coast. Early projections through Sunday from the NWS Hydrometeorological Prediction Center (HPC) are suggesting widespread rains of 1” to 2” or more for the northern half of the viewing area, with totals rising above 3” and even 4” closer to the coast.

Titan9 PrecisionCast rainfall projections through Saturday evening. 
In fact, the threat of heavier rains to our west are sufficient enough that as of this afternoon the NWS has posted all of Louisiana -- from south of Alexandria and west of the Atchafalaya Basin -- under a FLASH FLOOD WATCH from Friday morning through Saturday evening!

Tuesday, May 8, 2012

Some Relief from the Heat

By Jay Grymes & Steve Caparotta

After a scattering of showers and t-storms for Tuesday afternoon and evening, the rains will subside through the overnight.  We’ll keep a slight chance of rain -- about 20% -- in the forecast from midnight until sunrise, with better rain chances returning during the day on Wednesday.
A cool front will work its way through southern Louisiana overnight and push out over the northern Gulf into the morning, but mid-level energy behind that surface front will mean keeping scattered rains in Wednesday’s forecast.  We’re currently setting Wednesday’s rain chances from late morning into the afternoon at about 40% , with cooler and less humid air prevailing by the evening hours.
Many WAFB communities could see morning lows dip into the upper 50°s for Thursday and Friday morning, thanks to the “continental” air mass that takes over late Wednesday.  Thursday should be a beauty, with highs in the low to mid 80°s.  Friday should be just fine for downtown’s Live After Five with mainly fair to partly cloudy skies.  We’ll sneak a very slight chance of rain (less than a 20% chance) into the latter half of Friday -- not really enough to worry about.
Our extended outlook includes a return of scattered showers and t-storms through the weekend.  Guidance is currently projecting a non-tropical low to emerge over the western Gulf near the Mexico/south Texas coast on Friday and begin a trek east-northeast across the Gulf, approaching the Louisiana coast by late Saturday or early Sunday.  Timing for the low’s arrival along the LA coast varies between models, but that system looks like it will make for a pair of wet days - - for now, we’ll go with 50-50 rain chances for both days.  As that Gulf low continues to track east away from Louisiana, our next cool front is projected to approach from the northwest, keeping decent rain chances in the forecast for next Monday and even Tuesday.
Given the run of wet weather we’re forecasting from Saturday into Tuesday, is there any good news?  How about temps running a tad on the “cool” side for this time of year, with morning lows in the low to mid 60°s and highs in the low to mid 80°s.  That may not be great news, but at least it will be a departure from the persistent warmer-than-normal weather we’ve been experiencing over most of 2012 thus far.

Monday, May 7, 2012

Here Comes the Rain (Again)!

By Jay Grymes & Steve Caparotta

A SEVERE THUNDERSTORM WATCH remains in effect for the Mississippi counties in our viewing area until 8PM, prompted by a line of storms moving north-to-south through central Mississippi.  These storms have produced some severe t-storms, with hail and gusty winds, but the greatest threats are probably frequent lightning and locally heavy rainfall. 

That said, and with storms now north and south of the Baton Rouge metro area, keep your eyes to the skies this afternoon and evening, as we anticipate more showers and storms breaking out in the coming hours.  Truth is, this past weekend’s evening action -- both Saturday and Sunday -- surprised us in terms of regional coverage, intensity, and the fact that most of the stormy weather came late in the evening, with much of it developing well after sunset.

We could still have storms bubbling after sunset this evening, but the weather should quiet down later in the evening.  Our warm, moist air mass will mean another muggy night and early morning start, with sun-up temps running near 70°.  And the afternoon will be a full near-summerlike combination of heat, humidity and a return of scattered showers and storms.  Look for a Tuesday high in the upper 80°s, with a 30% to 40% chance of rain for your neighborhood.

A late spring cool front will slide through the state late Tuesday into Wednesday, and while the boundary should be out over the coastal waters by Wednesday afternoon, guidance is showing south Louisiana rains extending after the front has passed.

Behind the mid-week front, we’ll get a little relief from the heat.  We’re looking for morning starts in the upper 50°s to low 60°s for the rest of the week and into the weekend, and afternoon highs for metro BR will be in the low 80°s into the weekend as well. 

(And boy has it been hot!  For you weather trivia buffs, it looks like the first 7 days of May 2012 will rank as the 3rd “warmest” first week of May in more than 80 years!)

Towards the end of the week, the extended outlook suggests that a non-tropical low may develop in the western Gulf and track east-northeast towards the Louisiana coast.  With the low to our south, that will draw in slightly cooler and drier air from the north and northeast, helping maintain cooler weather through the weekend.  But those weekend highs in the low 80°s will come at a price:  our weekend forecast calls for rains on Saturday and Sunday as a result of that Gulf low.

And speaking of heat, we’ve posted a little note about the unusually-warm first four months of 2012 on the WAFB Weather website:

Friday, May 4, 2012

Staying Summer-like into the Weekend

By Jay Grymes & Steve Caparotta

A note of interest for skywatchers before we get into the weekend forecast...
Saturday night will not only provide a full moon, but something known as a "super moon". What exactly is that? A "super moon" occurs when the timing of a full moon coincides with perigee -- the time of moon's closest approach to earth in its orbit. Astronomers tell us Saturday's full moon could appear to be as much as 14% bigger and 30% brighter than any other full moon in 2012. The best time to catch what could be a neat view of the moon is likely around moonrise (7:36 p.m. in Baton Rouge) due to a known optical illusion that tricks our eyes into thinking the moon is even larger when it first appears above the horizon.
The heat has set in, and we don’t anticipate much of a change for the next several days! Today marks the second straight day with a high of 90° at Baton Rouge Metro and there could be more ahead into the weekend.
Morning starts will remain in the upper 60°s to around 70° for the Baton Rouge metro area with patchy sunrise fog each morning through Monday.  Warm and moist Gulf air will remain in place into early next week.  With afternoon highs expected to climb to near 90° through the weekend, we expect mid-afternoon Heat Index values to climb into the mid to upper 90°s -- a word of caution for weekend Golfers and those working their backyard gardens as most of us are not yet quite “acclimated” to this summer-like heat!
Weekend “outdoor activities” call for sunscreen, fluids and breaks from the warmer-than-normal weather.  But the good news is that we don’t see a need for the umbrella on Saturday or Sunday!
Well, okay ... given the heat and humidity over the coming days, we can’t completely rule out a rogue afternoon shower or two, but the vast majority of us will remain dry.  That’s good news for the continued clean-ups underway in northern and eastern Ascension Parish as well as portions of western Livingston Parish following Wednesday’s flooding rains!
Our extended forecast currently projects a cool front sliding across the Bayou State sometime between Tuesday and early Wednesday.  At this point, that front doesn’t look like a very energetic from a rainfall perspective -- and the truth is we’ll have to watch through the weekend to see if this scenario really does materialize.

That said -- and based on what we see for now -- the anticipated mid-week cool front will mean a slight drop in temperatures and humidity for the latter half of next week compared to what we are expecting for the upcoming weekend.
And don’t forget:  Saturday is Cinco de Mayo and FestforAll will be running both Saturday and Sunday in downtown Baton Rouge.  Enjoy!

Thursday, May 3, 2012

By Jay Grymes & Steve Caparotta

We’re still getting a few “late” rain reports following Wednesday’s deluge.  On Wednesday evening we noted the rainfall bull’s eyes over central Tangipahoa and eastern Livingston parishes, but from what we’ve seen, the core of heaviest rains stretched across northcentral and northeastern Ascension Parish (the greater Prairieville area) and eastward into western Livingston Parish. 
Doppler Radar estimated rainfall for Wednesday. While the locations of the heaviest rains are accurately depicted, note that the radar was underestimating rain amounts, by several inches in some instances.
Widespread totals in that area ranged from more than 5” to at least one reliable report in excess of 8”, with one caller claiming a whopping 13.5” of rain!  With most of that rain falling in a three to six hour period, the storm event works out to be something on the order of roughly a “once-in-50-years” rainstorm based on 6” to 8” range of totals.  (If the 13.5” is real, that would rank as something beyond a “1-in-100-year” rain!)

If there is any good luck to be considered, it would have to be that the weather preceding Wednesday’s “mega-rain” had been relatively dry through the prior 12 days or so.  Had the days leading up to the mega-rain bee a bit more typically in terms of spring rains, Wednesday’s dousing would have led to even greater property damage!
A drier and warmer weather pattern will set-in for the coming days, as the disturbance that fueled Wednesday’s rains slowly drifts farther to the east (and north) while an upper-level ridge takes hold over the nation’s Southeast.  In fact, we could see some highs at or above 90° for Friday and into the weekend! 
While upper-air ridging will inhibit the development of afternoon showers and add to the mid-afternoon warm-up, we’ll keep the “return flow” (inflow of Gulf moisture) running continuously through the next 7 days.  While we’re not expecting any significant rain until the middle of next week (at the earliest), Gulf humidity will certainly be in place with dewpoints in the upper 60°s to low 70°s.  That will mean warm-and-muggy mornings, with patchy sunrise fog likely just about every day. 
And with highs climbing to around 90° and dewpoints near 70° over the next several days, that will translate into mid- to late-afternoon Heat Index values in the mid 90°s -- truly summer-like!

Tuesday, May 1, 2012

Good Rain Chances Wednesday

By Jay Grymes & Steve Caparotta

And the “warmer-than-normal” days just keep on coming ... in fact, the current outlook from the NWS Climate Prediction Center suggests that there is about a 75% chance that temperatures through July will continue to run “normal to warm,” so don’t be looking for any prolonged cool spells in the coming weeks.
May-June-July temperature outlook from NOAA's Climate Prediction Center. The outlook shows a 39% chance of 'above-normal' temps, 35% chance of 'near-normal' temps, and 26% chance of 'below-normal' temps during the 3-month period.
Water demand by lawns and gardens tends to be a little higher with this kind of summer-like warmth, and many of you are looking for a little rainfall to break the recent run of mainly dry days.  It looks like about half or more of you are in luck, as our Wednesday afternoon forecast calls for a 50-50 chance of rain across the WAFB viewing area.
We’ll start Wednesday off with some clouds and patchy fog.  Sunrise temps for metro Baton Rouge will run in the mid to upper 60°s, a tad on the muggy side for this time of year and continuing a run of morning starts in the 60°s over the past several mornings.  To our southeast, a broad, non-tropical disturbance over the eastern Gulf will continue to track towards the central Gulf Coast on Wednesday, and that will be the weather-maker that generates scattered showers and t-storms through the afternoon and early evening.
Titan9 PrecisionCast projection for 1 p.m. on Wednesday showing scattered showers and t-storms around the area.
That disturbance will be rotating clockwise around the surface ridge of high pressure settled along the southeast U.S. Atlantic Coast.  The disturbance will continue to move inland Wednesday night into early Thursday, and it may provide just enough lift and instability to keep a few showers in the area overnight and into Thursday morning.
So we expect patchy fog returns with possibly a shower or two for Thursday morning.  As we get into Thursday afternoon, whatever is left of the disturbance will continue to move away from our area.  While the primary rainmaker will exit the region, we’ll still have the flow off the Gulf and plenty of daytime heating to interact with that Gulf air, so we’ll keep isolated afternoon showers in the Thursday forecast.
For now, the weather pattern becomes a little redundant for Friday and through the weekend: muggy mornings with patchy fog and sunrise temps in the 60°s with isolated afternoon showers and highs in the upper 80°s to near 90°. 
Factor in the humidity and it will have a summer feel to just about each and every afternoon!  Are you ready?