Friday, May 22, 2015

Scattered Rains Return This Weekend

By Jay Grymes & Steve Caparotta

May 15th WAFB First Alert Quickcast:

- increasing rain chances through the next 3 days

Friday … finally.  Seems like it was an extra-long work week .. .like someone snuck an extra work day into the week.  But maybe that is because we were waiting on the upcoming Memorial Day weekend: a 3-day break for many and the unofficial kick-off of summer!

But take a moment to remember the purpose of Memorial Day: a day of remembrance for those who have died in service of the United States.  The National Moment of Remembrance, established by Congress, asks Americans, wherever they are at 3 p.m., local time, on Memorial Day, to pause in an act of national unity for a duration of one minute.

No complaining about today’s weather .. and our forecast from last night, with a 30% to 40% chance of rain, proved to be a big bust.  So what happened?  The cool front we showed you last night moved farther south and out over the northern Gulf waters, allowing a more significant “dry out” for today.  Although a couple of spotty showers popped up during the afternoon, the lower humidity (and lower temperatures) made for a nice Friday afternoon, even with the cirrus cloud deck.

So now the question is, “When will the front start its northward retreat?”

We expect it starts moving back in our direction later tonight, but its return will be slow enough that we get another fairly pleasant morning start for Saturday.  It’s won’t be as cool for the Red Stick tomorrow morning as it was this morning - - how about a low of 63° at BR’s Metro Airport and lows in the 50°s near and north of the LA/MS state line - - but we’ll still see some mid to upper 60°s for Saturday’s lows.

Into the afternoon, the warm front will have lifted north of the Capital City, allowing a return of Gulf humidity. That will mean a better chance of rain across the area, but we still think that the majority of neighborhoods will stay dry.  Set rain chances for Saturday afternoon at about 30% or so. 

After that, however, rain chances continue to climb for Sunday and Memorial Day Monday.  We’ll be hopeful for just a 30% to 40% rain chance for Sunday afternoon, but our outlook has “rain likely” for Monday. Expect morning lows in the low 70°s for both Sunday and Monday.  Plan for highs in the upper 80°s for Sunday, with temperatures falling in the afternoon where the rains do fall.  For Monday, with rain chances at 60% to 70%, the cloudy, wet pattern will keep highs in the low 80°s for many of us.  In addition, while it won’t rain all day in your backyard on Monday, rains are likely to be falling somewhere in the viewing area for the better part of the day.

We’ve got “rain likely” for the Tuesday forecast too, with scattered to likely rains for Wednesday.  Heading into Thursday and Friday, we expect to ease back on the rain chances at 30% to 40% or so for both days.

So take advantage of a “drier” pattern for Saturday and Sunday, have a “Plan B” ready for Monday afternoon … and enjoy the weekend. 

Thursday, May 21, 2015

A Little Less Rain on Friday

By Jay Grymes & Steve Caparotta

May 21st WAFB First Alert Quickcast:

- sct’d rains return for Friday, a little quieter on Saturday
- back to scattered showers & storms for Sunday & Memorial Day

A cool front continues to slide southward across the Bayou State this afternoon.  Low-level Gulf moisture, moderately cool air aloft and the approaching cool front are all working together to fire afternoon showers and t-storms.  The first Severe T-Storm Warning of the afternoon was posted just after 2:00pm for Amite and Pike counties -- since then there have been a couple of additional Warnings up near the LA/MS state line and a Flash Flood Warning for parts of Livingston Parish in the mid afternoon. 

To these warnings you can add-in a few strong storms across the WAFB viewing area through the afternoon that produced brief downpours, frequent lightning and probably some pockets of small hail.  Scattered rains are likely to continue into the late afternoon before slowly waning into the evening hours.

We will keep isolated rains in the overnight forecast, trailing off to mainly coastal activity by the early morning.  Scattered showers and storms are expected to return for Friday afternoon.

The cool front mentioned above will ease its way into the coastal waters overnight, then start a slow drift back to the north on Friday.  That set-up should allow for slightly lower dew points (less humid air) to settle over the region tonight, with Friday morning temperatures slipping into the mid to upper 60°s for folks along and north of the I-10/12 corridor.  But with the front slowly retreating northward - - a warm front - - tomorrow and into Saturday, the lower humidity will be short-lived.  Expect a morning start in the upper 60°s for Saturday’s sunrise, then it’s back to morning lows at 70° or more for Sunday and Monday as the Gulf air returns.

We still expect Saturday to be the “driest” of the next four days, with Saturday afternoon rain chances running around 20% to 30%.  As we head into Sunday and Monday, increased instability will mean better rain chances, especially for the afternoons.  Saturday’s lower rain chances also suggest that it will have the warmest afternoon readings over the coming days.  After many communities top out in the low to mid 80°s for Friday, we’re calling for upper 80°s for most WAFB neighborhoods for Saturday.  Plan for mid 80°s on Sunday and Memorial Day (Monday) as we dodge scattered afternoon rains on Sunday and scattered-to-likely rains on Monday.

We’re sticking with scattered to numerous showers and storms for the better part of next week too, with morning lows in the low 70°s for the Capital City and afternoon highs in the mid 80°s through mid-week.  We could see a modest drop in rain chances for the second half of the coming work week, and that will likely be accompanied by a return to upper 80°s for afternoon highs.

Bottom line: it’s about as close to a summer-like pattern that we can be for May.  We recommend that you keep the umbrella within reach for most of the next seven days.

Wednesday, May 20, 2015

Scattered, Mainly Afternoon Storms Persist

By Jay Grymes & Steve Caparotta

May 20th WAFB First Alert Quickcast:

- scattered rains return for Thursday & Friday
- a little “drier” for Saturday?

Once again a round of energetic storms cut through portions of the WAFB viewing area today, delivering some active lightning, brief heavy downpours, and possibly a little hail for portions of Pointe Coupee, West Baton Rouge, East Baton Rouge and the Felicianas during the early afternoon. Those storms continued moving east into Livingston, St. Helena and Tangipahoa parishes while slowly dissipating.  A second cluster of storms over central Acadiana fizzled out during the mid-afternoon as they approached the Atchafalaya Basin.

As of 3:30pm, there had been no warnings issued anywhere in or near the WAFB area, and Doppler activity across the southern parishes continued to wane.  While it is not likely to be entirely dry through the late afternoon and evening, it does look like it will be reasonably quiet -- at least weatherwise -- through the evening commute.

Our forecast for the next couple of days calls for a return of mainly-afternoon showers and t-storms for the next two days: set rain chances at about 50% for Thursday and then 40% for Friday. 

A weak cool front will sag southward through the southern parishes over the next couple of days.  The latest projections for the NWS Weather Prediction Center show the front draped along the coast by Thursday evening and then slipping into the northern Gulf waters by Friday morning.  After that the front is likely to meander near and along the coast before effectively dissipating on Saturday.

That should give us some slight relief from the recent summer-like humidity and allow lows to drop into the 60°s for the Red Stick on Friday and Saturday mornings.  More importantly for many of us, the set-up should deliver a relatively dry Saturday: we’re going with just a 20% rain chance for the day.

By Sunday, however, the warm-and-moist Gulf air mass will have fully recovered ... and that means back to scattered afternoon showers and t-storms for both Sunday and Memorial Day Monday.

Our outlook through the next seven days keeps us out of the 90°s, with highs still hanging in the mid to upper 80°s each day -- about normal for afternoon highs for this time of year.  In fact, some of the wetter days in the upcoming run may be a tad cooler-than-normal, depending on the timing and arrival of afternoon rains.  As for lows, most will be a couple of degrees above normal -- often at 70° or more for the Capital City area -- at least partly due to Gulf humidity maintaining dew points near 70°.

Monday, May 18, 2015

Scattered T-Storms Return on Tuesday

By Jay Grymes & Steve Caparotta

May 18th First Alert Quickcast:
- scattered showers & storms return for Tuesday
- unsettled pattern holds through the work week

While today wasn’t the busiest weather day that we’ve dealt with in the past few weeks, it was far from quiet for many WAFB neighborhoods. Scattered showers and storms -- with some of those storms on the strong side -- have been the local weather story for much of the day. 

A lightning-laden thunderstorm -- likely producing some small hail -- tracked from west-to-east across Iberville, southern Pointe Coupee and WBR parishes around noon time. Not long after, locally-heavy downpours over portions of Iberville, Ascension and Livingston parishes prompted the NWS to issue a Flash Flood Warning for those areas.

However, what most of us experienced today is relatively minor compared to the flooding rains across the northern half of the state! Radar estimates are showing widespread 3” to 5” totals up there with pockets exceeding 8” to 10” of rain in just the past 24 hours. Sadly, one fatality has resulted from the intense rains in the northern parishes.

Our area rains will wind down later this evening, and we will carry spotty showers in the forecast through the overnight and early morning hours. Plan for a muggy start to Tuesday, with sunrise temperatures around 70° for the Capital City. In addition to the spotty wake-up showers, be ready for some patchy fog for Tuesday’s morning commute. 

Our forecast is generally wet for Tuesday afternoon, although rains won’t be as widespread as occurred today: we’re posting rain chances at 50% across the viewing area for tomorrow. Maybe more importantly, we don’t anticipate anything like the downpours observed across northern Louisiana. Most that do get rain tomorrow will likely see totals come in at well under one-half-inch. Expect highs to climb into the upper 80°s Tuesday afternoon before the rains arrive.

We’re easing back on the rain chances for Wednesday to 30%, with scattered showers and t-storms in the forecast for both Thursday and Friday. And again, although isolated larger totals will be possible, most WAFB neighborhoods can expect less than one-inch of rain right through Friday and Saturday.

But expect no relief from the humidity: the “muggies” stay with us as Gulf air will remain in place all week, providing a moist-and-unstable atmosphere to fuel daily rains. Morning lows will trend around 70° to the low 70°s for the Red Stick right through the weekend, while afternoon highs will run in the upper 80°s for most, if not all, days.

An upper-level trough will remain positioned over the western states throughout the week while the central Gulf coast see-saws between weak upper-air ridging and the effects of upper-level southwestern flow around the base and eastern flank of that western trough. When the weak ridging dominates, rain chances will drop off a bit; by contrast, the upper-level southwesterly flow will provide a boost to rain chances when it dominates.

All in all, the WAFB region can expect isolated to scattered mainly-afternoon rains right through the upcoming weekend. With that kind of pattern we recommend that you keep the umbrella nearby although don’t expect to see rain in your neighborhood every day.

Friday, May 15, 2015

Staying Unsettled Through the Weekend

By Jay Grymes & Steve Caparotta

May 15th WAFB First Alert Quickcast:

- scattered to numerous showers and t-storms through the weekend

Today’s first wave of showers and storms moved inland off the Gulf around 10:00am, reaching the Baton Rouge metro area right around the lunch hour.  That band of rains continued to march to the north at about 25-30 mph, reaching the LA/MS state line around 1:45pm.  Doppler radar detected some small hail in a few of the t-storms within the first wave, but none of those storms were deemed ‘severe.’

At the same time, a second, broken band of rains began developing over the coastal parishes and it too headed north.  Both of these bands of rain and storms had a Gulf “sea-breeze” look to them, fueled by a very moist and unstable air mass over the region.

Rains will taper off later this evening, but unlike the past two days, we will keep isolated rains in the overnight forecast.  In fact, for Saturday’s sunrise we’re anticipating spotty showers - - most likely to develop closer to the coast.  The flow off the Gulf continues tonight and through the day on Saturday: our muggy air mass keeps Saturday morning lows in the 70°s for the Capital area, with mostly cloudy skies and pockets of fog for the morning start.

Rains will slowly increase into mid-day and the afternoon on Saturday: we’re calling for a 50% to 60% rain chance through the day.  Much like today, we don’t expect a severe weather outbreak, but one or two storms could be on the strong side, capable of small hail, frequent lightning and locally-heavy downpours.  Most folks should get through the day with one-half inch of rain or less, although a one-inch bull’s eye here and there are certainly possible.

A disturbance over South Texas appears to be slowly headed in our direction and that could enhance Saturday’s rain chances along the Central Gulf Coast.  A look at the models through the next several days shows a  series of upper-level troughs rolling into the U.S. from the Pacific, with upper-level disturbances sliding around the “bottom” of those troughs and riding the upper-level flow into our region. 

Translation: more of the same likely for Sunday and right into next week.  Keep the umbrella within reach!

None of these days are likely to become “all day” rains, but at this point we’re going with rain chances at 50% or better through mid-week, and carrying scattered mainly-afternoon rains in the forecast for the end of the work week too.  The muggy air mass means morning lows at or above 70° for metro Baton Rouge just about all week, with afternoon highs ranging from the mid to upper 80°s for most days, depending on the onset timing of the afternoon rains.

Here’s hoping that you can get some outdoor time this weekend!

Thursday, May 14, 2015

Good Rain Chances into the Weekend

By Jay Grymes & Steve Caparotta

May 14th WAFB First Alert Quickcast:

- rain likely for Friday  
- scattered showers and storms for the weekend

For the second straight day, a large portion of the WAFB viewing area remained dry.  However, there were a few afternoon thunderstorms in our viewing area and while none of them achieved ‘severe’ thresholds they were quite active in terms of lightning. And while the storms were fairly isolated, there was a decent concentration of activity right around the city of Baton Rouge.

Whatever action that does pop-up will subside through the evening and we’ll go dry through the night.  Plan for a partly to mostly cloudy start to Friday, staying dry for the morning commute, but once again with patchy wake-up fog.  It will be a muggy start as well, with sunrise temperatures in the low 70°s for many WAFB communities.

Our recent run of drier weather ends today -- the modest mid-level ridging that has been in place moves east with a mid/upper southwesterly flow taking charge.  The shift in upper-air flow means a series of disturbances to the region beginning with the first tomorrow.  That is why we’ve got rain likely for Friday afternoon and scattered-to-likely rains for Saturday and Sunday too.

With the clouds and rains, some parishes may not even reach the mid 80°s for highs on Friday.  We don’t anticipate a round of severe storms on Friday afternoon, but we could see one or two stronger thunderstorms develop, and a warning or two can’t be entirely ruled out.  It won’t be an all-afternoon rain for everyone, but we do suspect that somebody will be dealing with showers and storms in some part of the viewing area for just about the entire afternoon and into the early evening.

We’ll quiet things down for Friday night into Saturday morning and then do it all over again for Saturday afternoon.  Saturday’s rain coverage may be a tad less widespread than Friday’s, but not much less in terms of areal coverage.  Saturday’s highs will top out in the mid 80°s for most of us.

Unfortunately, Sunday is looking fair wet too: we’re going with 50-50 rain chances for Sunday afternoon with highs in the mid to upper 80°s. 

And the weather outlook stays with scattered showers and storms right through most or all of next week.  A series of upper-air troughs will move from the western U.S. into the Plains, with each driving disturbances through the Gulf region.  At the same time, a steady flow of Gulf moisture into the lower Mississippi will provide the fuel for afternoon rains.

Our suggestion:  keep the umbrella nearby all week long.

Wednesday, May 13, 2015

Fairly Dry Again on Thursday

By Jay Grymes & Steve Caparotta

May 13th WAFB First Alert Quickcast:

- only a few showers today, much the same for Thursday
- higher rain chances for Friday and the weekend

After back-to-back afternoons (Monday & Tuesday) with weather warnings posted for parts of the WAFB area, today’s quieter pattern was welcomed by most.

We started the day under the clouds, and even the afternoon was marked by more clouds than sun.  We didn’t go through the day entirely rain-free, but weak upper-level ridging placed a “cap” on the atmosphere, inhibiting the ability for afternoon clouds to develop vertically.  (It’s the upward growth that allows our morning cumulus clouds to become afternoon thunderstorms.)

What showers that did develop today were located mainly to the west of metro Baton Rouge.  Just about all of today’s showers should be gone by sunset.  Later tonight, like last night, we’ll stay under mostly-cloudy to cloudy skies with Thursday morning lows dipping to the upper 60°s to around 70° for the Baton Rouge metro area. 

Thursday morning’s commute will be a dry one, with a pocket or two of mainly-light fog.  Headed into the afternoon, temperatures will climb into the mid to upper 80°s around the area under a mostly cloudy sky. Today's atmospheric "cap" will be slightly weaker tomorrow, so we'll post rain chances at 20% to maybe 30% for Thursday afternoon -- the majority of WAFB neighborhoods will remain dry once again. Plan for afternoon highs in the mid to upper 80°s.

By Friday, the “cap” should be gone and daytime heating will work with our humid Gulf air to get afternoon showers and storms going again.  In addition, our guidance is showing a fairly healthy disturbance tracking from the west across the lower Mississippi Valley on Friday, adding a big boost to the already unstable air mass.  Right now, it’s not looking like an all-day rain, but showers and t-storms are likely for Friday afternoon.  With the clouds and rains, highs on Friday may only make it into the low to mid 80°s for most of us.

The outlook for the weekend may not be quite as wet as our thinking for Friday, but unsettled weather remains the forecast for both Saturday and Sunday.  Expect scattered afternoon showers and storms for both days with Capital area morning lows in the low 70°s and afternoon highs in the mid 80°s, with a few neighborhoods sneaking up into the upper 80°s.

Headed into next week, we don’t see much in the way of significant changes to the afternoon weather pattern.  Although the NWS Weather Prediction Center (WPC) is currently showing a cool front approaching South Louisiana on Tuesday, the WPC has the front stalling over the southern parishes on Wednesday -- a situation not too different from what we’ve seen the past 24 hours or so. 

That means more of the same: scattered mainly-afternoon showers and t-storms for Monday through Wednesday, with some potential for stronger storms next week as the front draws near.