Wednesday, June 26, 2013

Hot, Mainly Dry Again on Thursday

What more can you say about our weather then, “Boy, it’s hot!”

While the heat does have many of us talking, truth is that temperatures are running near or only slightly above-normal for most. For instance, today’s low of 72° at Metro Airport is actually a degree below the ‘normal’, while afternoon highs in most spots have been near or just a degree or two above the ‘normal’ of 92°. Feel better about the heat now? I didn’t think so.

And if you’re not a fan of hot weather, then you probably won’t like the forecast for the next few days. Highs could reach the mid 90°s in some WAFB neighborhoods as a ridge of high pressure continues to influence our weather.

As we discussed yesterday, that ridge is expected to begin a westward shift by Friday, which should open the door for a few more showers and t-storms headed into the weekend. We’ll post rain chances around 30% on Friday and 30% - 40% for Saturday. The prevailing flow over the weekend will be from the northwest, which can sometimes be supportive of a few stronger storms. We’ll keep an eye on that, particularly for Saturday.

In a change from our forecast yesterday, it now looks like some drier air will sneak into the area for the second half of the weekend, limiting our rain chances on Sunday. Additionally, highs should be closer to 90° (instead of the mid 90°s) from Sunday into early next week.

Speaking of next week, our extended guidance points toward a cool front approaching from the north and potentially stalling nearby. Assuming that occurs, rain chances should be a bit higher for the early to mid portion of next week.

Closing out today with some information for “Lightning Safety Awareness Week”, here’s a look at just how frequent lightning is in our part of the world. Vaisala – a private company that maintains one of the largest (if not the largest) lightning detection networks in the U.S. – has calculated lightning strike densities (or strikes per square mile) for each state dating back to 1997. Florida leads the way at 24 strikes per square mile, followed by Louisiana at nearly 20 strikes per square mile. The top 5 are rounded out by Mississippi (18 strikes/sq. mile), Alabama (16 strikes/sq. mile), and Arkansas (15 strikes/sq. mile). So, the bottom line here is that our state (particularly south Louisiana) is one of the true lightning ‘hot spots’ in the country and we need to take the associated dangers seriously! 

Tuesday, June 25, 2013

Hot, Relatively Dry Next Couple of Days

As anticipated, a building ridge of high pressure helped limit shower and t-storm activity around the area today. We’ve still seen a few t-storms through the afternoon, with most of the action for areas east of metro Baton Rouge. Look for any lingering rains to end shortly after sunset.

Overall, the pattern will change little for the next couple of days. We’ll keep rain chances less than 20%, with highs topping out in the low to mid 90°s. In fact, with added sunshine and less rainfall, the scales will likely tilt a little more in the direction of the mid 90°s through the end of the week.

Headed into the weekend, it looks like the upper-level ridge of high pressure helping to keep us relatively dry for now will begin to break down and retreat westward. As it does so, rain chances will gradually increase. We’ll go with 30% on Friday, 30% - 40% on Saturday and 40% - 50% by Sunday. 

A cool front will also approach the area by late in the weekend into early next week, helping to enhance our rain chances. Scattered to occasionally numerous showers and t-storms appear possible for Monday and Tuesday of next week.

As we continue through “Lightning Safety Awareness Week”, here are some statistics that hammer home the lightning threat locally:
  • Baton Rouge averages 70-75 days a year with thunderstorms. Or, in other words, about 1 out of every 5 days produces a t-storm 
  • Louisiana ranks 5th nationally in the number of lightning fatalities since 1952 with 142. Recent fatalities include one here in Baton Rouge in 2010, 2 in Ponchatoula in 2012, and 1 in Lake Charles in May of this year 
  • It is estimated that the odds of being struck by lightning in your lifetime are around 1 in 10,000. Some estimates place the odds even higher than that. Consider those numbers versus your odds of winning the lottery. 

And finally, we should have a good opportunity to view the International Space Station (ISS) passing overhead tonight. The ISS should appear in the northwest sky around 9:12 PM, pass just about directly overhead and exit in the southeast sky around 9:15 PM. Good luck if you attempt to see it!

Monday, June 24, 2013

A Bit Drier Rest of This Week

A surge of Gulf moisture and a little added instability in the atmosphere helped rains get cranking around the area a bit earlier than normal today. As a result, much of the activity had shifted north of the WAFB viewing area by mid-afternoon, although there were some pockets of heavy rainfall still located in SW Mississippi.

After near-normal rain coverage over the last couple of days, the trend will be toward somewhat drier weather through the remainder of the week. An upper-level ridge of high pressure will remain centered well to our west, but its eastern flank will expand in our direction, helping to limit rain coverage and produce slightly hotter temperatures. We’ll set daily rain chances at 20% or less through the week, with highs ranging from the low to mid 90°s.

By the weekend, the ridge will retreat back to the west, potentially opening the door for somewhat better rain chances to return. At this point, we’ll still only set weekend rain chances around 30%, but it’s possible they could go a little higher. In addition, the position of the ridge to our west will result in a northerly flow over the WAFB viewing area. While that doesn’t favor widespread rains, if storms do develop, they tend to be stronger and more ‘electrified’ (produce more lightning) under a northerly flow. That’s another trend we’ll monitor into the weekend.

Speaking of lightning, NOAA has declared this week, “National Lightning Safety Awareness Week”. In conjunction with that, figures released from a new study indicate that since 2006, 64% of lightning fatalities in the U.S. occurred while people were participating in leisure activities. Fishing leads with the way with 26 deaths, followed by camping (15 deaths), boating (14 deaths), soccer (12 deaths), and golf (8 deaths). The stats may be somewhat surprising given that many often see golf as one of the most dangerous outdoor activities when lightning is around. Indeed, it is certainly dangerous, but the fact that fishing, camping, and boating are at the top should grab our attention since all three are popular in this part of the world. NOAA has tried to make the threat of lightning simple to understand by urging, “When thunder roars, go indoors”!

And finally…the tropics remain quiet today and will likely remain that way for much of this week. 

Friday, June 21, 2013

Staying Hot, Humid on Saturday

By Jay Grymes & Steve Caparotta

The meandering, quasi-stationary front over the Gulf States has definitely shown some staying power over the past couple of days, but it’s looking like the boundary is just about ready to fizzle out.  Without support from mid/upper-level disturbances, it simply didn’t have sufficient form to enhance lift today and generate more widespread rain.  Without these mechanisms, today’s showers were dependent upon solar heating, sea-breezes, and outflow boundaries and had to struggle against weak upper-level capping.  As a result, Friday -- the first official day of the 2013 summer -- ended up ‘hot and mainly dry’ for most WAFB neighborhoods.

We’ll keep isolated rains in the Saturday forecast as well, then increase those rains to the “scattered” category for Sunday with mainly-afternoon showers and t-storms.  And for next week?  It looks like a rather normal -- and repetitive – summertime forecast for the work week: morning lows in the low 70s and afternoon highs in the low 90s for most communities with ‘hit-or-miss’ afternoon t-showers just about every day.

With dew points generally in the low to mid 70°s, the low-level air remains on the most-side through the week, and that should mean afternoon hourly Heat Index numbers running from the mid 90°s into the triple digits through the coming seven days, at least.

Beyond that, there really isn’t much to say about our forecast.  There are no depressions or storms in the tropics to talk about; in fact, none of the current tropical waves in the Atlantic Basin appear to offer much threat of organization, at least in the short term.

So what about this “supermoon” that some are talking about for this weekend (June 22 and 23)?

The Moon’s orbit around the Earth is elliptical, which means that there are times when the moon is a bit closer to the Earth (perigee) and times when the moon is farther from the Earth (apogee) over the course of the 27.5 days that it takes for the Moon to complete one trip around the ‘Blue Marble.’  Modern era astronomers label the moon a “supermoon” when (1) it is in perigee and (2) also is a “full” moon.  In fact, this weekend’s “supermoon” is labeled by some as an “extreme supermoon” because the moon will be closer to the Earth during this weekend’s perigee than it will be during any other perigee this year!

So how big will the moon appear?  Well, not as big as some of the social media chatter may suggest.  The moon will only appear roughly 10% to 12% larger than normal -- only regular moon watchers will really notice the difference.  But the good news is that we should have good back-to-back viewing nights for watching the “Rose Supermoon” (June full moons are called “rose” or “flower” moons by some).

So we’ll close out today’s discussion with a reminder to take care of yourself, your family and the pets in the weekend heat!

Thursday, June 20, 2013

A Little Drier Friday & Saturday

By Jay Grymes & Steve Caparotta

Some morning rains and clouds through much of the day slowed the normal mid-day warm-up, but it looks like many WAFB neighborhoods still made the 90°s for their afternoon highs.  It’s been an interesting afternoon with no severe t-storms, but Titan9 Doppler has been showing some very strong and lightning-charged thunderstorm pockets through the afternoon. 
We expect the rains to ease off and be essentially all-but-gone by or before sunset, with mostly fair skies on the way through the overnight.  Wake-up temps for the Red Stick on Friday morning will be in the low 70°s with Friday highs reaching the low 90°s for most of us.
A weak, quasi-stationary front continues to linger from east-to-west across the central Gulf Coast states and we expect that front to still be meandering over the region into Friday. 

So why not the more widespread rains like we saw on Wednesday?  Mainly because we’ve not had the broad mid/upper-level disturbances passing overhead to help fuel storm development like we had on Wednesday.  The front alone is simply not providing enough lift to get as more widespread rain event underway.
By the way ... summer “officially” begins just four minutes past midnight tonight (12:04 AM CDT, June 21).  The Northern Hemisphere’s summer solstice occurs when Earth's axis is the most tilted toward the Sun -- with the North Pole “leaning” towards the Sun.  Because of this orientation, the length of time with sunlight is also at its maximum for all locations north of the equator, with Baton Rouge receiving more than 14 hours of “direct” sunlight (assuming clear skies).  Starting on Saturday, the daylight period will begin to shorten, although the rate of change is less than one minute per day.

Heading into the weekend, we’re posting fairly typical numbers for late June: morning lows in the low 70°s, afternoon highs in the low 90°s and rain chances running around 30% for Saturday and 30% to 40% for Sunday.  And the summer season weather monotony looks like it will extend into next week with more of the same: low 70°s, low 90°s and isolated to scattered mainly-afternoon t-showers just about every day.

As of 4PM, the National Hurricane Center has downgraded Barry to tropical depression (TD) status.  Barry made landfall along the Mexico Coast earlier today -- around 8AM -- with maximum sustained winds of 45 mph.  Having now been over land for roughly 8 hours (as of 4PM), the loss of warm-water energy and interaction with the higher elevations to the storm’s west are taking a toll on the system and Barry will likely degrade below TD status later this evening or tonight.  But Barry is still proving to be a formidable rainmaker for some sections of coastal Mexico.

Wednesday, June 19, 2013

Rain, the Tropics & a Waterspout!
A busy day in the WAFB Storm Center today!
Radar suggests that most of the WAFB viewing area received rain today. In fact, for some locations to the west of Baton Rouge, Wednesday was a very wet day. Titan9 Doppler radar shows as much as 2” of rain and more fell over parts of WBR, southern Pointe Coupee, eastern St. Martin, eastern St. Landry and sections of Iberville parishes, with a bull’s eye of 3” to nearly 4” centered over northern Iberville Parish.
And for most WAFB neighborhoods, that rain was welcomed. Not only has it has been a bit drier-than-normal for many communities over recent weeks, but we’ve been on a 9-day run with highs at 90° or above for the Red Stick, so the break in the heat -- thanks to the rains and clouds -- was a bonus! With a high of just 82° for Wednesday afternoon at Metro AP, that makes today’s afternoon readings the “coolest” for Baton Rouge since May 22nd -- that’s better than 4 weeks!
But don’t get used to it -- we expect the 90°s to be back for Thursday, Friday and right through the weekend!
A stalled front and eastward-moving upper-level disturbance produced today’s rain, but we don’t anticipate a repeat performance any time soon. The disturbance will continue to move away from the viewing area this evening and the quasi-stationary front draped over the coastal states looks like it will slowly lose its definition over the next couple of days and eventually dissipate.
So let’s go with a 20% to 30% rain chance for Thursday with only isolated, mainly-afternoon showers expected for Friday. As we head into the weekend, we’ll return to a fairly typical June weather pattern for Saturday and Sunday: low 70°s near sunrise, low 90°s for the afternoons, and afternoon to early-evening rain chances in the 30% to 40% range for both days.
And did you see some of the still shots and video of the waterspout that hit Grand Isle on wednesday afternoon?  here's a sample:
And yes, Tropical Depression #2 has been upgraded and is now Tropical Storm Barry. Data this afternoon from an Air Force “Hurricane Hunter” showed that the pressure had fallen and peak winds had increased enough to confirm the upgrade. But Barry’s time over water is short, with a landfall expected along the Mexican Coast on Thursday morning.

Tuesday, June 18, 2013

Looks 'Wetter' for Wednesday

They’ve had some heavy rains, strong storms and even some localized flooding in the northern parishes today, but for many of us in the WAFB viewing area, it has remained dry. True, we did have some passing showers and a few t-storms in our viewing area this afternoon, especially up along the LA/MS state line, but most of those were quick-moving and short-lived, producing little in terms of accumulations.
Even with today’s relatively quiet weather so far, we’ll keep a slight chance of rain in the evening and overnight forecast. We’ll also carry isolated showers in the forecast for the morning drive, then take Wednesday afternoon rain chances up to about 50-50.
The upper-level ridge that has been a dominating feature in our recent weather is finally breaking down. A cool front is sagging southward today and will stall over the northern half of our viewing area later tonight and early tomorrow. At the same time a series of mid/upper-level disturbances will continue to move west-to-east across the coastal states. Add in daytime heating and Gulf humidity and you can see why rain chances will be noticeably higher for Wednesday.
Somewhat surprisingly, however, the wetter pattern doesn’t hold on for long. We’ll drop rain chances for Thursday down to the 30% to 40% range, and drop it another 10% for Friday as a ridge attempts to become re-established over the eastern U.S. before the end of the work week. Heading into the weekend, we’ll keep isolated to scattered mainly-afternoon t-showers in the forecasts for both Saturday and Sunday.
Temps throughout the rest of the work week and into the weekend will run very near the norm for this time of year: low to mid 70°s for morning lows and low 90°s for afternoon highs.
Tropical Depression #2 (TD#2) continues to move over across Central America -- the latest position estimate puts the poorly-defined center over Mexico and not too far from the coastline to the Bay of Campeche. The current best-guess forecast track takes TD#2 over the southern Bay of Campeche by tomorrow and possibly remaining over the water until late Wednesday or early Thursday. Still, there is little opportunity for the depression to undergo much development before landfalling again on Thursday. Still, TD#2 may prove to be a proficient rainmaker for parts of Mexico, but the system offers no threat to U.S. interests.

Monday, June 17, 2013

Better Chances for Rain This Week

Titan9 Doppler was showing a few showers on Monday afternoon with a couple of t-storms in the WAFB viewing region, but all was mainly quiet across the immediate BR metro area as of 3PM. We’ll keep isolated showers in the WAFB area forecast for the rest of the afternoon and early evening, then ending soon after sunset. 
No doubt about it, summer heat has really kicked in this month! Today marks the 8th straight day with highs at 90° or above at Metro Airport (BTR) and for some of you that run of heat has been essentially rain-free. In addition, we’ve got returning to the 90°s just about all week long.
For the trivia buffs ... BTR averages about 19-20 days every June with highs of 90° or more. Today marks the 11th day at 90° or more for this June. Based on BTR records since 1930:
. . . the most June days at or above 90°: all 30 days during June 2006 and June 1960
. . . the fewest June days at or above 90°: only 4 days during June 1983 and June 1961

As we’ve seen the past couple of days, rain chances will remain on the low side -- say around 20% to 30% -- for Tuesday. Fortunately, the upper-level “heat ridge” that dominated our weather over the weekend is weakening and retreating a bit to the west -- that should allow for better rain chances by Wednesday into Thursday. Set rain chances for Wednesday and Thursday in the 40% to 50% range -- and for many, the gardens and lawns could use a little rain.

It looks like upper-level ridging will return as early as Friday, and the will mean a drop in forecasted rain percentages for Friday through the upcoming weekend. But for the time being, we aren’t yet anticipating a return of the mid 90°s for the coming weekend.

For the College World Series, the Tigers take on the UNC Tarheels in an elimination match-up on Tuesday at 2:00PM. The weather cooperates at T.D. Ameritrade Stadium for Tuesday afternoon: mostly sunny to partly cloudy, game temps in the low 80°s with winds light and ranging from the ENE to the ESE.

In the tropics, the National Hurricane Center “upgraded” the vigorous tropical wave located over the Gulf of Honduras (NW Caribbean) to Tropical Depression #2 (TD #2). TD #2 is moving inland across Belize, headed towards northern Guatemala and the Yucatan. Given that it is moving over land, development is not an issue in the short term. However, the forecast guidance does take the system into the southern Bay of Campeche by Tuesday or Wednesday. At that point, conditions appear somewhat favorable for development -- and the National Hurricane Center currently shows the system briefly achieving tropical storm strength before its final landfall in Mexico. If TD #2 were to become a tropical storm, it would be named Barry.

A couple of other disorganized tropical waves are evident over the open tropical Atlantic, but none show imminent signs of organization.

Thursday, June 13, 2013

Temps Remaining Above-Normal This Weekend

By Jay Grymes & Steve Caparotta

Warmer-than-normal weather will persist for at least another three or four days -- afternoon temps in the 90°s coupled with an abundance of Gulf humidity will continue to push daily maximum Heat Index readings above 100° for many WAFB neighborhoods right through the weekend. 

Our forecast for Friday and the weekend remains virtually unchanged.  Mid/upper-level ridging will be the primary controller for our weather for Friday and Saturday, with the ridge starting to flatten (weaken) late Saturday into Sunday.  For most of us, hot-and-humid with little in the hopes of a cooling shower will be the rule for the next few days.

Although the guts of the upper ridge remains in place, it still looks like that “cool” front we’ve been advertising this week will indeed slide south during the latter half of the day Friday into early Saturday as a “backdoor” cool front.  Don’t expect much of a change though -- the front will add a few percentage points to rain chances on Friday and produce a very modest drop in dew points and the morning low for Saturday, but that’s about it.  Expect highs in the mid 90°s for both days.

We’ll go with a 20% rain chance on Friday, with only spotty showers for Saturday. 

As we mentioned, the outlook calls for a weakening of the ridge by Sunday.  Now we are not talking about a major change, but a less robust “cap” on the atmosphere which should allow for a few afternoon showers.  So let’s be generous and say isolated showers -- uh, maybe -- for Sunday afternoon. 

The forecast for next week stays on the “drier” side, with rain chances generally around 20% through the week.  But we also expect those daytime highs to back down into the low 90°s rather than the mid 90°s through the work week - - not a big change, but worth noting nonetheless.  And after a run of mid 90°s, low 90°s may not seem so bad?

As for the tropics, there are a couple of waves -- one to the east of the Lesser Antilles and another in the SW Caribbean -- but neither is showing any real threat for development at this point.

Heat & Humidity Combine for Added Discomfort!

-- Jay Grymes / WAFB Storm Team
Afternoon temps in the 90°s coupled with an abundance of Gulf humidity will continue to push the Heat Index readings up to near or even above 100° for most WAFB neighborhoods just about every day this week.
As you know, the Heat Index represents the perceived ‘feels like’ temperature for humans and is often referred to as the “apparent temperature.” The Heat Index (HI) is a subjective measure that makes a number of assumptions about the state of an individual, including type of clothing, the amount physical activity, even the person’s size and weight. The HI, therefore, is a reference number, a guideline, designed to approximate what one would “feel” given a combination of temperature and humidity under light winds and shaded conditions. And remember, the “apparent temperature” can increase by as much as 10° to 15°F under direct mid-day sunshine.
The human body has a built-in “cooling system” -- perspiration! Yet we fight perspiration constantly throughout the South Louisiana summer. It may not seem to make sense, but sweating is actually designed to cool the body. How? Heat is removed from the body by the evaporation of sweat -- it’s the same as the effect when you dab your skin with rubbing alcohol. The alcohol quickly evaporates, pulling heat out of your skin through the evaporation process and leaving you with a cooling sensation.
So why doesn’t the sweating process work better? Because of the normally high water-vapor content in our south Louisiana summer air -- our high humidity.
The more humid the air around us, the less efficient the perspiration/evaporation process. And when the air is very humid, the opportunity for our sweat to evaporate can go to near zero -- and then say hello to that sweat-soaked shirt!
The dew point temperature is one of our better indicators of the humidity level of the air. (You may recall that when the air temperature and the dew point temperature are equal, the relative humidity is at 100%.) The higher the dew point, the more water-vapor being held by the air. For Baton Rouge, summer season outdoor dew points are routinely in the low to mid 70°s and can climb into the upper 70°s to near 80° when conditions are right. By comparison, air-conditioned locations often will try and maintain an indoor dew point temperature below 60°. (To get a sense of what this means in terms of humidity, to go from a dew point temperature of 60° to a dew point of 75° requires that the amount of water vapor in the air must nearly double!)
For Baton Rouge, a somewhat typical summer afternoon will see outdoor air temperatures climb into the low to mid 90°s with dew point temperatures in the low to mid 70°s – no doubt about it, that combination is unpleasant to say the least! For example, a combination of an air temperature of 95° with a dew point of 75° yields a Heat Index of 107° -- considered “Dangerous” when one is exposed to that kind of heat for prolonged periods without relief. Of course, on individual days it can get even hotter and more humid for the Red Stick. What’s more, there are a number of days during just about every summer when the Heat Index stays in the triple digits for several hours. In fact, we sometimes see these extreme heat days come back-to-back-to-back.

The bottom line: heat can be a killer. In fact, some estimates suggest that, on average, 300 or more Americans die each year as a direct or indirect result of extreme heat.

Tuesday, June 11, 2013

More Heat, Less Rain Ahead

The upper-level ridge over the west-central U.S. continues to slowly ease its way to the east, increasing the strength of the “cap” over Louisiana. Remember, by a “cap or “lid,” we are referring to high pressure in the mid- to upper-levels of the atmosphere. This cap not only suppresses cloud development (and therefore inhibits rainfall), but also promotes sinking air. Sinking air must warm as it descends, so the sinking process actually adds heat to the lower-levels of the atmosphere.
We’ll stay warmer-than-normal and mainly dry through the rest of the week. Red Stick residents should plan on muggy mornings with patchy fog and sunrise temps in the low to mid 70°s while afternoon highs under mostly-sunny to partly-cloudy skies reach the mid 90°s.
These won’t be record afternoon temps but still take care in the heat, especially when under the direct sunshine. Remember, the mid-day sunshine can add as much as 10° or more to the “feel” of the air ... and that’s before we consider the Heat index impact of our traditional summertime humidity.
Now, okay ... a handful of you will still see a passing afternoon shower just about every afternoon this week. Even as the upper-level ridge sets-up right over top of us towards mid-week, there are still going to be a couple of pop-up places where the rising air punches high enough through the upper-level cap and produce a localized shower. The Gulf air mass at the surface is obviously very warm and very moist, and warm-and-moist air is, by definition, unstable and quick to rise.
Think of it like this: with the abundance of low-level unstable air, some fraction of it is going to find a “weakness” in the overhead cap. Almost like the fork holes your mom puts in her pie crust to let some of the steam out while it bakes. So yes, we could see a couple of blips on the Titan9 radar just about every afternoon this week, but they will be few and far between for the next few days.
We’re watching the potential for a “backdoor” cool front to slip southward and try to make it to the Gulf Coast on Friday. Signals are a bit mixed at this point, but given the time of year, the odds of the front pushing into and through the WAFB viewing area are on the low side. Still, the front could get close enough to put a crack in the atmospheric cap, and the closer the front gets the better the potential rain chances on Friday afternoon.
For now, I’m thinking that the front won’t make it this far south and only gets close enough to increase rain chances to about 20% for Friday afternoon. Not much of a big deal, really, and that would still be rain chances lower than normal for this time of year. Of course, we’ll keep an eye on the forecast developments with this scenario over the coming days.
Another day passes and we remain quiet in the tropics.

Monday, June 10, 2013

Getting Drier -- and hotter -- this week!

Jay Grymes / WAFB Storm Team

Titan9 Doppler was showing a few showers on Monday afternoon with a couple of stronger t-storms to the south and east of Baton Rouge, with most of the action loosely linked to the afternoon “sea breeze.” We expect all of that action to die-down as we head into the evening and go to mainly fair skies overnight.
Tuesday will begin with a few clouds and sunrise temps in the low 70°s for metro BR. We’ll go to partly cloudy skies for the afternoon, with rain chances on Tuesday at less than 20%. 
It looks like the main weather story for Tuesday and the rest of the work week will be about the heat. Our forecast is calling for highs in the low to mid 90°s across metro Baton Rouge for Tuesday, with highs on most days this week up around the mid 90°s. Factor in the humidity and we’re talking about peak afternoon Heat Index numbers climbing into the triple-digits just about every day this week.
At the same time, we’re calling for a run of “mainly dry” days, with rain chances for most WAFB neighborhoods running at under 20% each day right into the weekend.
Why the “hot-and-dry” spell? As you know, in the summertime, the two go hand-in-hand. Reduced cloud cover means less chance for rain and more direct solar heating. 
Our forecast for the next couple of days calls for upper-level ridging (high pressure in the mid to upper levels of the atmosphere) to take charge and persist right into the weekend. Ridging suppresses cloud development and actually causes the upper-levels to sink towards the surface -- literally pushing downward from above. This downward motion effectively puts a cap on the lower levels of the atmosphere, minimizing the ability to hot, humid air to rise (and to develop into clouds).
The cap isn’t always perfect, so some rising still can occur, allowing for occasional, spotty showers. But the upper-level ridging and resulting cap means little or no chance for rains like we saw over the weekend -- at least not for the next several days, and probably not through the weekend.
So get ready for some serious summer season heat all week long.
So far so good in the tropics -- all remains “quiet” there.

Thursday, June 6, 2013

Storms Remain Possible Overnight

By Jay Grymes & Steve Caparotta

Although most of the Baton Rouge metro area stayed dry today, we’ve seen some very active weather all around us.  A outflow boundary (a mini 'cool front' produced by earlier storms to our north) is moving through the WAFB region this afternoon and evening, and upper-level divergence (increasing winds aloft) has aided the lift and taken advantage of the warm, moist and unstable surface air, fueling the storms that have developed.
We’ve seen a handful of Severe T-Storm Warnings posted this afternoon for areas to the east, southeast and south of metro BR, with the storms generally moving to the southeast at 15-20 mph.
In addition, we’re getting some signals from short-term meteorological models, including our in-house “PrecisionCast” RPM, that we could see some additional showers and storms extending into the evening and overnight.  We’ll keep rain chances at about 30% through the night and early morning, with lows in the 70°s.  Don’t be surprised to be awakened tonight by rumbles of thunder!
We’re also maintaining that 30% rain chance through Friday afternoon -- not great news for the LSU Tigers and Oklahoma Sooners and the fans of the NCAA Super Regional, but it could be worse.  We’re not worried about an all-day rain, so they should be able to get the 6:00 PM game in even if they have to deal with a delay.

We’re posting 20% to 30% rain chances for Saturday and Sunday -- again, not ideal for the Super Regional schedule.  But it is summer in south Louisiana, and if you live here you know that this is just what summer is supposed to be like.
Monday looks like the day with the best rain chances over the upcoming 7 days, with a somewhat drier outlook for the remainder of next week.  Of course, drier often means warmer, and that’s just what we expect for Tuesday through Thursday next week:  lows in the low to mid 70°s, highs in the low 90°s and a humid air mass that makes the afternoons feel like the mid to upper 90°s.

As for T.S. Andrea ... she intensified more than expected last night and earlier today.  The 4PM NHC Advisory shows a tropical storm with peak sustained winds of 65 mph -- rather impressive for the first storm of the season and for a storm that looked poorly-organized and sheared just a day ago.  As expected, Andrea headed into Florida, making landfall along Florida’s “Big Bend” at 4:40 PM.  Andrea is expected to accelerate tonight and tomorrow, reaching the Carolinas by Friday afternoon and becoming ‘post-tropical’ by late Friday or early Saturday.  Andrea has produced some pockets of heavy rain and some wind damage in the Sunshine State and preliminary reports indicate ‘she’ has spawned a dozen tornadoes over the Florida peninsula.

Wednesday, June 5, 2013

Andrea Forms in the Gulf

By Jay Grymes & Steve Caparotta

Titan9 Doppler has been picking up a few showers and isolated t-storms through the afternoon.  Those pockets of rain have been moving generally from ESE-to-WNW around the larger-scale circulation associated with the broad low in the east-central Gulf.  We expect most of those afternoon and evening showers to fizzle-out shortly after sunset, although we won’t rule out a spotty shower or two during the overnight and into Thursday morning.

Our thinking for Thursday and Friday has changed a bit since yesterday.  We’ll keep a 30% rain chance in the forecast for Thursday afternoon but rather than increasing the rain chances into Friday afternoon, we’re going to bring them down a bit.  If you remember, yesterday we were talking about a 40% to 50% chance of afternoon showers and storms for Friday.  Now we’re thinking something on the order of a 20% rain chance for Friday morning, then continuing into the afternoon at about 20%, if not a tad lower.  That’s great news for the NCAA Super Regional at Alex Box ... and generally good news for anyone hoping for a dry Friday evening!

Why the change?  The cool front headed our way from the Southern Plains is now expected to lose a good bit of its definition before it arrives, which means we’ll lose some of the “lift” that a frontal boundary would have provided to kick-off showers and storms.  Remember earlier this week how we questioned whether that front would actually make it all the way through the viewing area and deliver a brief dose of less-humid air?  We should still get a slight drop in dewpoints for late Friday into Saturday, but not a big cool down.

However, the slightly-drier air that arrives on Friday will mean a drop in rain chances for the latter half of Friday and extending into the weekend.  Therefore, in addition to the reduced rain chances for Friday, we’re posting afternoon rain chances at 20% for Saturday and Sunday.  That should be even more good news: not just for the Super Regional but also for anyone hoping to enjoy some weekend outdoor time.

And of course, we’re watching that low in the Gulf.  A Hurricane Hunter left Biloxi around lunchtime today and found strong enough winds, along with a circulation center that was defined well enough to upgrade the area of disturbed weather to Tropical Storm Andrea, the first named storm of the Atlantic hurricane season. Andrea will continue to battle wind shear and some dry air on its western side, so little intensification is expected before it makes landfall potentially in the 'Big Bend' area of Florida by late Thursday. It will have little direct impact on our weather and even those headed to the beaches should be fine by Friday, although the surf will probably be a bit on the rough side.

Don’t forget, you can customize your own tracking of this system with WAFB’s Hurricane Tracker, available at -- we think you’ll like this on-line tool!

And of course, with that “something” in the Gulf, now is a great time to consider: is your 2013 ‘Hurricane Plan’ good-to-go?  Need some ideas?  A refresher?  For guidance and ideas to get yourself, your family and your property prepared, check out:
-’s Hurricane Center

Tuesday, June 4, 2013

Staying Hot, Isolated T-Storms

By Jay Grymes & Steve Caparotta

As of 4PM, we’re watching spotty showers on Titan9 Doppler over the Baton Rouge metro area, with some larger showers and a few lightning strikes well off to the east.  That all should end around sunset as we go to mainly fair skies tonight.  But the “muggies” will stay with us right into Wednesday morning with sunrise temps in the low 70°s.

We’ll keep rain chances at 20% for Wednesday afternoon, then up them to 30% for Thursday. 

A weak and diffuse quasi-stationary front has lingered over southeast Louisiana today, helping kick-up a few stronger storms around metro New Orleans, Lake Pontchartrain, and over parts of the Pearl River basin.  That front will lift northward as a warm front over the next 24-36 hours -- at the same time, a cool front currently over the Southern Plains will slowly continue to head our way.  That front should be draped across Louisiana by early Friday, adding to the local instability and lift and pushing rain chances up into the 50-50 range for Friday afternoon.  Unfortunately, however, indications are that this cool front will wash-out over the weekend, which means no relief from the heat or humidity in our viewing area.

The Friday forecast could be a bit of an issue for the Super Regional at Alex Box, but the outlook is much better for Saturday -- and Sunday if needed.  We’re calling for only isolated afternoon showers for both weekend days, but you can bet both days will be hot and humid.

The only other big weather story for us: that mess in the southern Gulf.  Currently labeled as “Invest 91L,” it’s a broad and poorly-defined low pressure area with most of the associated convection located well to the east and southeast of the presumed zone of lowest pressure.  The National Hurricane Center is currently giving the area a 40% chance of becoming a tropical depression (gets a “number”) or tropical storm (gets a “name”) over the next 48 hours.

Many of the forecast models are suggesting improved organization and strengthening in the coming days; at the same time, most of the models take the low pressure into Florida by Friday.

Monday, June 3, 2013

Staying Hot, Isolated Storms

By Jay Grymes & Steve Caparotta

Titan9 Doppler was showing spotty showers on Monday afternoon, mainly over the coast parishes.  The “cool” front that we’ve been tracking for the past couple of days just doesn’t want to exit the southeastern parishes -- instead, it has been meandering to our east and south as a quasi-stationary front and appears likely to remain in the weather mix for another day or two.
Although we did get a mainly-dry day as expected, we did not get to enjoy the relief from the humidity that we had hoped for -- and it looks like that will be the story for Tuesday as well.  With the front still lingering in the region, we’ll see a slight dip in temps overnight tonight but not as much as thought.  Look for lows on Tuesday morning in the upper 60°s for metro Baton Rouge, but many communities just south of the Red Stick may not get out of the 70°s.
We’ll keep Tuesday’s forecast relatively dry, although this weather set-up suggests that we could again see a few showers and t-storms by Tuesday afternoon.  Fair to partly cloudy skies on Tuesday will mean plenty of sunshine, and that should help push daytime highs into the low 90°s for most WAFB neighborhoods.

For Wednesday, we’ll keep rain chances at 20% or less -- so most will stay dry.  But by Wednesday afternoon, our traditional summertime humidity will be back thanks to “return flow” (winds off the Gulf).  Heat, humidity and the flow off the Gulf will combine to bring rain chances back into the “scattered” category for Thursday and Friday.
In the meantime, forecast models continue to show that the area of low pressure currently over the southern Gulf could get a bit better organized as we head into the end of the work week.   At this point, chances for tropical development into a depression or tropical storm do not appear particularly high but it certainly deserves watching.  At this stage, whatever it becomes appears headed towards Florida.

As we head into the weekend, we are getting mixed signals as to what to expect.  The NWS Weather Prediction Center has another “cool” front moving into and through the lower Mississippi Valley on Saturday, with the boundary effectively dissipating as it reaches the coast.  For the time being, however, we’ll stick with a more traditional summertime forecast for Saturday and Sunday: hot-and-humid, with scattered afternoon t-showers.

Saturday, June 1, 2013

"Cool" Front on Sunday?

As we expected, a few showers and a couple of rumbles of thunder around the WAFB viewing area today, but most of us stayed “rain dry,” although if you spent any time outdoors today then you know all about the heat and humidity. Heat Index numbers around the viewing area reached the mid 90°s, with a few neighborhoods hitting the upper 90°s!

Whatever rain is still on Titan9 by 7PM will be just about all gone soon after sunset. We’ll go to partly cloudy skies, but stay fairly muggy overnight with lows in the low 70°s for the Red Stick - - and a little higher south of metro BR.

Like we’ve seen the past several mornings, we could spot a shower or two in the early morning hours Sunday, but most of us will remain dry through the morning. However, the “cool” front we’ve been talking about all week is still on schedule to arrive tomorrow, and that will mean scattered afternoon and evening shower and t-storms. For now, we’ll stay with a forecast for a 50% coverage -- so not everyone gets the rain.
The front will be a little slower to clear the region than I had thought, so we’ll keep a slight chance of rain in the forecast for the first half of Monday, with clearing during the second half of the day.

And as we’ve mentioned, this “cool” front won’t be all that cool -- in fact, the afternoons could actually get a little warmer behind the front for Tuesday and Wednesday. But you should notice the drop in humidity by late Monday into Tuesday. The lower dewpoints should also mean morning lows slipping into the 60°s for a couple of mornings.

Sadly, the less-humid air mass won’t stay around long. The air moistens-up by late Wednesday, with scattered afternoon showers returning to the daily forecast for Thursday, Friday and Saturday.