Friday, March 29, 2013

Increasing Clouds, Rain Chances This Weekend

By Jay Grymes & Steve Caparotta

Our Easter weekend forecast may not be exactly what you have been hoping for.

After a morning start in the low 50°s, Saturday’s forecast calls for a sun/cloud mix to mostly cloudy skies with isolated afternoon t-showers.  Highs climb into the upper 70°s for most WAFB communities.  Yes, you might have to dodge a raindrop or two, but most stay dry through the day -- so keep those Saturday outdoor plans in place.


Our Easter Sunday forecast looks like it may be wetter than what we’ve been thinking for the past few days.  We’re still calling for a mainly-dry start to the day, but we’ve added fog to the morning forecast.  Rain moves in for the afternoon and evening.  The latest model runs are sending some mixed signals about Sunday’s weather: while we don’t anticipate a severe weather event, our in-house RPM model is suggesting that some WAFB neighborhoods could see upwards of one-inch or more of rain!  That’s NOT what the Easter Bunny ordered!

Sunday’s rains will be powered by several features: a slow-moving cold front to our north will help maintain a steady in-flow of moist Gulf air, while daytime heating and a “weakness” aloft will combine to enhance afternoon instability.

The weather remains wet into Monday, with a follow-up cold front to our north getting a good push from a southbound Canadian air mass.  As the front slides southward into the lower Mississippi Valley, it will get a boost from an upper-level system currently located over the eastern Pacific -- that should make for a noticeably cooler and fairly soggy Tuesday.

Unfortunately, it looks like the cold front slows its southward advance on Tuesday into Wednesday, lingering over and along the northern Gulf and helping to keep our weather unsettled through mid-week.  In fact, the last couple of runs from the GFS model holds the wet weather in here through Thursday before finally clearing out on Friday.  Highs for Tuesday, Wednesday and Thursday will likely top-out in the 60°s, making for cool and damp early April weather.

Our extended outlook has afternoon temps rebounding into the 70°s on Friday under sunshine, with the longer-range outlook suggesting a decent pair of days for next weekend.

Tuesday, March 26, 2013

Another 'Freeze' on the Way!
- Tuesday, March 26th
Metro Airport just missed tying the record for Tuesday’s low, dipping to 33°. But Weather Watchers and WAFB viewers across most of the Florida Parishes and all of SW Mississippi reported a morning freeze. At McComb, the freeze lasted about 4 hours ... at Hammond Airport, the freeze was just over an hour long.
We’ll see another round of brief freezes for Wednesday morning. In fact, we’re thinking temps for Wednesday’s sunrise may be a degree or two (or three?) lower than those for Tuesday morning. Durations won’t be all that much longer than what you experienced on Tuesday morning, but it should mean an “official” freeze for Metro Airport this go-around.
High pressure will settle right overhead this evening and overnight: that means tonight’s winds should be much lighter than those recorded through much of late Monday night and early Tuesday morning. We believe that it was the wind last night that slowed the Monday evening temperature fall and kept Metro AP just above freezing throughout. In fact, with Metro AP temps still in the upper 40°s at 11:00pm Monday night, I was surprised that the airport actually got down to 33°. But the winds subsided between 3:00-4:00am, allowing the temp to drop from 41° at 3:00am to 33° at 7:00am.
By Wednesday afternoon, that same surface high pressure will be moving to the east, allowing the start of some east to southeast flow and bringing Gulf air back into the viewing area. As you well know, that will start a slow warming trend, with highs climbing into the low to mid 60°s for Wednesday afternoon and highs back into the “March-like” 70°s for Thursday, Friday and into the weekend.
Our forecast stays dry through Friday, but we bring a slight chance of rain into the Saturday forecast. Highs on Saturday should reach the upper 70°s.

Easter Sunday is looking a little dicey. We think that all should remain dry for area sunrise services although there is likely to be a decent cloud deck and/or some areas of fog in the morning. And for the young’uns, we’re thinking that most of the morning egg-hunts should be okay. But guidance is indicated scattered showers and a few t-storms by the afternoon. For now, we’re posting rain chances for Sunday between 30% to 40% -- not an all-day washout and as of now there are no early indications of a severe weather threat. With a little luck, you could get through the day, including that backyard crawfish boil, without any rain.
The extended outlook for Monday and Tuesday remains “unsettled,” with a cold front currently projected to move north-to-south through the lower Mississippi Valley on Tuesday.

Monday, March 25, 2013

How rare is this?
A freeze this late in March? What’s going on here? Assuming that we do hit a 'freeze' in metro BR over the next morning or two, just how rare is that? The "average date" of the last spring freeze for Baton Rouge has long-since passed – that was more than one month ago, on February 24th!
March freezes certainly can’t be called rare, but by the time we get this late in the month, that’s a different issue. We found only five Baton Rouge freezes after March 25th ... and that’s going all the way back to 1892! That’s just five freezes this late in the season in more than 130 years, or about one every 25 years -- maybe not “rare” but certainly “not to be expected!”
Of those five late season freezes, two occurred in April. The latest freeze ever for the ‘Red Stick’ was on April 13th in 1940. The second April freeze occurred on April 4, 1987 -- as a matter of fact, that April 1987 freeze is the last time we’ve seen a BR freeze after March 25th -- that’s going back 26 seasons! And what about the other three post-March 25th freezes?
March 29, 1899 ... and an extra-rare back-to-back pair of freezes on March 26 and 27, 1955! How about that for irony? Our current forecast calls for only the second time ever to have back-to-back freezes this late in the season (Tuesday & Wednesday mornings) -- and they happen to fall on the exact same dates as the only other time on the record books ... 68 years ago to the day!

For Baton Rouge, even if we do get to freezing, it won't last very long on either morning. And we should keep in mind that it takes more than an hour or two of temps at/below 32° to have any serious impact, especially if the winds are light/near-calm. This is especially true given that we did get into the upper 50°s under sunny skies today (warming the soils) and will be there again tomorrow.

So don’t worry about the pipes.

For metro BR most of you can expect no more than a couple of hours near freezing … however, durations will be longer to BR’s north and east, and viewers near and north of the LA/MS state line can expect lows in the upper 20°s by Tuesday’s sunrise.

For most backyards, moving the extra-tender plants under an extended overhang or under the carport will be sufficient to protect them. A light sheet over low plants can be used if you are really concerned about buds freezing. Healthy, well-developed trees with branches well above the ground should be okay.

By Wednesday afternoon, the winds will come around from the east and southeast, and we will begin a slow-but-steady warming trend, taking us back into the 70°s before the end of the work week. Our forecast remains dry through Friday, with modest rain chances over the Easter weekend. We’ll have more on that later this week.

Friday, March 22, 2013

Sct'd T-Storms, Some Possibly Strong on Saturday

By Jay Grymes & Steve Caparotta

We’ve seen a few light, passing showers today but nothing significant and no t-storms.  No complaints about that, either.  Our forecast for tonight through early Sunday morning may sound a little confusing, so hang in there while we try to explain. 
We’re going with a 50-50 rain chance for the viewing area for Saturday, with most of those rains arriving after noon.  Sure, a few might see a passing shower or two in the morning hours but most of the action comes during the latter half of the day.
We’ll start Saturday off with a rather muggy and almost-warm air mass in place -- look for sunrise temps in the low to mid 60°s for most WAFB communities.  We’ll be positioned in the “warm sector” (located on the south side of a warm front and ahead of an approaching cold front) through the day on Saturday with warm-and-moist Gulf air taking afternoon highs up to around 80°!
Scattered showers and t-storms will develop across the warm sector, accounting for our expected Saturday rains.  But again, at 50-50 chances, not everyone gets wet.  And even for those that do get rain, most will see rain totals under one-half-inch with many coming in at well under one-quarter-inch.  There could be one or two larger rainfall bull’s eyes under some passing t-storms but this is not going to be a local heavy-rain event.  All in all, Saturday’s weather doesn’t sound very impressive, yet ... but there is a catch.

Upper-level winds and an unstable atmosphere will provide conditions that could allow one or two of the better-developed thunderstorms during the day to achieve “severe” status: large hail, damaging winds, even tornadic development.  We are not expecting a widespread severe-weather outbreak, but don’t be surprised if the NWS issues a warning or two -- maybe even a few warnings -- through the latter half of the day.
As we head into late Saturday and early Sunday, a low-pressure center tracking west-to-east along and near the Red River Valley will cross Arkansas, dragging a cold front through the Bayou State.  That front clears the clouds and delivers a shot of cooler and much less-humid air to our region.  Look for lots of sunshine and highs only around 70° for Sunday afternoon.

The Canadian air mass behind Sunday’s cold front will really take charge as we head into the work week.  In fact, it gets almost cold next week: we’re posting morning lows in the upper 30°s for Monday, Tuesday and Wednesday across metro Baton Rouge with highs only in the 60°s.

At least our current 7-day outlook stays dry through the work week.
Speaking of dry, have you noticed how dry the weather has been over the past several weeks?  After the “wettest” winter on record for Baton Rouge, we’ve definitely hit a dry spell -- a welcomed dry spell at that!  Today is only the fourth day during March with measurable rainfall for most WAFB neighborhoods, and many of our regional rain-reporting sites are posting less than 2” of rain for the month thus far.

Thursday, March 21, 2013

Where did I leave that umbrella?
Clouds moved into the area sooner than we expected, with mostly cloudy skies during the morning keeping lows in the mid 40°s for metro Baton Rouge. But it stayed dry today and will so through the evening.
The winds have come around and are now flowing off the Gulf -- that means increasing low-level humidity through the afternoon, evening and overnight. As a result, Friday morning lows will be as much as 10° warmer than this morning’s lows . . . and we’ll throw in a few morning showers to boot. As Friday wears on, rain chances will increase, climbing to around 40% for the afternoon.
A warm front will lift north out of the Gulf on Friday, putting the WAFB viewing area in the “warm sector” for much of the day. The front will essentially stall to our north for the latter half of Friday and remain there through much of Saturday. Low pressure will develop along the stalled boundary by Saturday afternoon and move east, pulling a cold front through the viewing area late Saturday into the pre-dawn hours Sunday. The weekend cold front sweep out into the Gulf during the day on Sunday, with a cooler and dry Canadian air mass settling over the lower Mississippi Valley.
This weekend frontal scenario means even a better chance of rain on Saturday compared to Friday. In fact, there now appears to be some potential for strong to severe storms starting Saturday afternoon and extending into the overnight hours. The NWS Storm Prediction Center has included most of the central Gulf Coast -- including all of the WAFB viewing area -- under a “SLIGHT RISK” for severe weather during this time frame.
The latest outlook for Saturday’s cold front suggests a significant boost in the storminess potential, with the forecast for instability ahead of the advancing front now looking sufficient for isolated storms capable of producing large hail, damaging winds and even a tornado or two. We’ll be watching this situation closely over the next two days to see if the guidance maintains this limited, but noteworthy, weather threat.

After the front clears the coast on Sunday, we should be set-up for an extended run of dry, but much cooler weather through next week.

Wednesday, March 20, 2013

Rains Return on Friday

By Jay Grymes & Steve Caparotta

Welcome to the first official day of spring!
We started off with clouds and pockets of light rain, keeping the morning cool and damp.  But as the cloud line moved from west-to-east across the viewing area, mid-day temperatures responded quickly, jumping as much as 10° in less than two hours for many locations.  The afternoon was a gem ... a great first day of the new season!

Clear skies, low humidity and light northerly winds will mean a considerable cool-down overnight, with a chilly start for Thursday -- we expect morning lows around 40° for the Red Stick, with 30°s for many WAFB neighborhoods to the north and east of Baton Rouge!  Thursday starts off mainly clear, with clouds slowly returning through the day.  You may also feel a slow but steady return of low-level moisture as southeasterly winds set in by Thursday afternoon.  The day’s warm-up will be slow, however, with highs only getting to around 70°.
Our forecast calls for highs in the mid-to-upper 70°s for Friday and the weekend, but the warmer weather will be accompanied by some rain on Friday and Saturday.  However, we still do not anticipate any active or severe storms with those rains, and the latest NWS Weather Prediction Center forecasts indicate that rain totals over the two days will likely remain under one-half-inch for just about everyone.

Still, we continue to struggle a bit with just what to make of the Friday-through-Saturday weather set-up.  By Friday morning, we expect to see spotty to isolated rains in the area.  Rain chances will increase somewhat during the day Friday, with scattered showers and a few t-storms possible during the latter part of the day.  Scattered showers and a few t-storms continue for Saturday, with rain chances a tad higher at about 50-50 for your backyard.

The Friday/Saturday wet weather will be courtesy of another mid/upper-level disturbance coupled with a frontal boundary that is expected to stall along the Gulf Coast region on Saturday.  By early Sunday, a Canadian dome of cool-and-dry air will push the stalled front out to the Gulf, allowing skies to clear and leaving us with a nice Sunday afternoon.
As the Canadian high-pressure ridge takes charge, we’ll enjoy a run of dry-weather days while getting a prolonged dose of cooler air -- highs from Monday through Wednesday will top-out in the 60°s, well below mid-to-late March normals.

Tuesday, March 19, 2013

Scattered Showers Wednesday AM

By Jay Grymes & Steve Caparotta

Today  -- Tuesday, March 19 -- is officially the last full day of winter.  For you trivia buffs, tomorrow is the Spring (Vernal) Equinox, with spring beginning at 6:02 AM (CDT).  The Equinox: 12 hours of daylight and 12 hours of dark, right?  Well, not exactly.  If you want to read the nuts and bolts, we go into a little detail at the bottom of today’s write-up.
As for our weather, it was a very pleasant day today and we’ll have no complaints about this evening.  But clouds will be on the increase overnight as a mid/upper-level disturbance to our west moves towards us through the night and over the lower Mississippi Valley during the first part of Wednesday.  Our most reliable models are sending mixed signals about the rain chances with this system, so we’ve “split the difference” and are calling for isolated-to-scattered areas of light rain during Wednesday morning, so be ready for patches of wet streets for the morning commute.

Skies should be clearing from west-to-east by mid-day, leaving us with a nice Wednesday afternoon.  Temps will be near 50° for metro BR at sunrise, with highs only climbing to about 70° or so for the afternoon, several degrees cooler than Tuesday’s high.  Canadian high pressure will maintain a north-to-NNE wind through the day and also keep humidity on the low side.
That Canadian surface ridge slides to the east on Thursday.  At the same time, a warm front will slide northward through the Bayou State, linked to a low-pressure center over the Southern Plains. 
From here into the weekend, the weather picture is still a little fuzzy.  Let’s try this . . . the Plains low moves east across the lower Mississippi Valley on Friday, dragging a cool front with it.  That front then stalls across southern Louisiana from the latter half of Friday into Saturday, keeping our local weather unsettled for both days. 
For the time being, we’re calling for mainly light to moderate scattered showers on both days, with t-storms possible, especially closer to the coast.  At this stage, we see no serious threat for severe weather and rain totals over the two days are expected to remain below 1” for most, if not all, locations in the WAFB area.
A surface low riding along that stalled frontal boundary from west-to-east reaches the mouth of the Mississippi by early Sunday while a second surface ridge of continental high pressure builds-in from the north and northwest of the coastal front.  Those two features will work together to push the front out into the Gulf.  That should leave us with a decent latter half of the day for Sunday, followed by noticeably cooler but dry days for Monday and Tuesday.

So, about that equinox: why do the sunrise/sunset tables show a few minutes more daylight on the Equinox than exactly 12 hours?  Which means “nighttime” is less than 12 hours.
The presumption that Equinox means exactly “12 and 12” is based on astronomical geometry (the relationship between the Earth and Sun) … and it would be essentially correct if there were no atmosphere.  First off, this “12 and 12” rule ignores the indirect sunlight we get before sunrise and after sunset -- the period officially referred to as “twilight.”  And twilight is a result of sunlight “scattered” by the atmosphere even when the solar disk is below the horizon.  (The moon, for example, with no atmosphere, has no twilight periods.)
In fact, there are three types of twilight -- Civil Twilight, Nautical Twilight and Astronomical Twilight -- each effectively defined by the amount of indirect lighting available.  (We’ll leave you to dig up the details of these three definitions.)
But even if we exclude “twilight,” the daylight period during the equinox (Remember, there are two each year: Spring/Vernal and Fall/Autumnal) is longer than 12 hours.  There are two basic reasons.
First, since the Sun is a “disk” and not a simply a point in the sky, the official “12 and 12” would occur when the solar disk was evenly split through the middle while “sitting” on each horizon -- in the morning and the evening.  But the official definition of sunrise/sunset is the time when the upper-edge of the solar disk is just touching the horizon -- when the upper edge of the solar disk just touches the horizon in the morning as it “rises” and when it just slips to even with the flat horizon as it “sets” in the evening.  The time it takes for the Sun to “move” from the disk’s mid-point to the upper edge (relative to the horizon) adds a couple of minutes to the official “daylight” period at the start and the end of the day.
Second, the Earth’s atmosphere refracts (bends) the Sun’s direct-beam light (the light from the solar disk).  Because of the refraction, we actually see the top edge of the solar disk before that edge has actually risen above the horizon from a purely geometric perspective.  So sunrise “appears” before it would actually occur if there were no atmosphere.  Likewise in the evening, atmospheric refraction keeps the solar disk above the horizon a little longer, delaying the time when the solar disk actually disappears from view.

For Baton Rouge, the combination of these two factors extends the daylight period (excluding twilight) about 8 minutes or so -- not exactly something to get all that worked up about, eh?  The added daylight time (still measured in a handful of minutes) gets a little a shorter as you get closer to the equator and a little longer as you move towards the poles.

Monday, March 18, 2013

Tricky Forecast Later This Week

By Jay Grymes & Steve Caparotta

Admittedly, this is shaping up as one of the tougher 7-day forecasts we’ve had to prepare in quite a while.  The guidance models are not in great agreement in terms of timing or intensity of wet weather during the coming week, especially towards week’s end and into the weekend.

We’ve got a cool front working from west-to-east this afternoon, but it doesn’t look like it will generate much, if any, rain for the WAFB viewing area.  We’re expecting the front to slide by late this evening, with the winds swinging around by or before midnight.  We’re anticipating a really nice day weatherwise for Tuesday, with mostly sunny skies accompanied by a noticeable drop in humidity compared to today.  We’ll start Tuesday off with clearing skies and sunrise temps in the 50°s and climb into the upper 70°s -- a day with a true spring feel.

For Wednesday, it looks like the clouds return and even bring a slight rain chance (about 20% or so) during the morning and mid-day hours as a weak disturbance rides west-to-east across the region.  It will be cooler too, with a morning start near 50° and afternoon highs only reaching the low 70°s.

Thursday currently shapes up with a sun/cloud mix through the day and a high only getting to around 70°.  For now we’ll go with a “dry” Thursday, but that may change with the potential for a few showers late in the day.

A stalled front draped across the Gulf coastal states will serve as the impetus for rains on Friday while a disturbance to the west gets better developed before arriving over the lower Mississippi Valley by Saturday.  This pair of features has us posting rain chances at roughly 50% for both Friday and Saturday, with a lingering 20% rain chance for Sunday morning.  Once all of that clears out we’ll really cool down – we’re calling for highs on Sunday and Monday in the 60°s and a forecast low for early Monday down into the 40°s.

So, with spring “officially” arriving at mid-week, we’ve had some questions about the threat for a late season freeze.  The climate statistics look like this:

For Baton Rouge, there is still about a 1-in-10 chance (10%) for another freeze this season.  The latest freeze in any year for the Red Stick was April 13, 1940 … when the temp briefly dipped to 31°.  Since 1930, Baton Rouge has recorded just two April freezes, the other occurring on April 4, 1987 (32°).

By comparison, there is still roughly a 1-in-3 chance for another freeze in McComb, where there have been a handful of April freezes over the last 60+ years (back to 1948).  In fact, there were 4 April freezes at McComb in 1987 and 3 in April of 1971.

And as our third example, Donaldsonville has only one April freeze in its time series back to 1930 -- the same April freeze that is on the record books for Baton Rouge: April 13, 1940.  Given its distance south of Baton Rouge, it comes as no surprise that Donaldsonville’s freeze chances over the next couple of weeks are less than 1-in-10.

Friday, March 15, 2013

Breezy & Warm This Weekend!

By Jay Grymes & Steve Caparotta

Just loving this current run of great weather days -- and the weekend looks like it will follow suit.  It will be a little warmer for Saturday and Sunday, and by Sunday afternoon you might get a hint of Gulf humidity in the air.  But all in all, this is going to be a great weekend weather-wise ... and a great last “official” weekend of the 2012-13 winter.
Ridging aloft -- and a southerly flow at the surface will make for the warmer weekend.  Sunrise temps on Saturday will be around 50°, with St. Patty Parade temps (parade times will be roughly 10am - 1pm) climbing from the mid 60°s to the mid 70°s, with Saturday’s high approaching 80° by the late afternoon.  There will be plenty of sunshine through the day, so if you are headed to the parade -- or simply planning on spending a lot of time outdoors -- you should give some serious consideration to a little sunscreen.

Sunday will be a degree or two warmer, but still lots of daytime sun.
We are still including a frontal passage in the forecast for late Monday into the pre-dawn hours of Tuesday.  While temps behind the Monday/Tuesday front will drop by as much as 5° to 10°, most of us will see little if any rain as the front swings through.  We’re posting rain chances at 20% for the time being, but that looks a little generous at this point.

Behind the Monday/Tuesday front, afternoon temps will top out in the low to mid 70°s for Tuesday through Thursday.  In the extended outlook, we see a better chance of rain arriving late on Wednesday and extending through Thursday.  Preliminary guidance suggests that most of us can expect between 0.5” to 1.0” with that system, with isolated rains possibly extending into early Friday.
Have a great weekend!

Thursday, March 14, 2013

Breezy & Warmer on Friday

By Jay Grymes & Steve Caparotta

And the run of good weather seems to get just a little bit better! More sunshine today and maybe just a little warmer -- and a forecast that says continued great weather right through the weekend. In fact, about the only thing you’ll need for Saturday’s St. Patty’s Parade might be a little sunscreen!

High pressure has settled over the central Gulf Coast today and will slowly ease to the east over the next two days. As it moves east, our winds will come around to the south and southwest, adding to the warming trend over the next few days. In fact, many WAFB communities will be flirting with the 80°s over the weekend and into early next week.

It’s been a “cool and dry” March so far. 11 of the 14 days this month -- including today -- have been cooler-than-normal, including the three morning freezes on March 2nd, 3rd and 7th. But we’re shaping up for a string of days that will be quite warm. As for the recent run of dry days, one might say that we were due for it given the record wet winter (Dec-Jan-Feb).

The national weather picture over the coming days still includes a southbound Canadian front, but that front is still expected to stall to our north during the weekend, becoming stationary along an Oklahoma-Arkansas-Tennessee line. However, a deepening surface low will develop over the Southern Plains along that stationary boundary during the latter part of the weekend. The low will track to the ENE and arrive over the mid-Atlantic states late Monday or Tuesday, and as that lows moves east, it will bring a trailing cold front through the lower Mississippi Valley. The timing still remains a little uncertain, but the latest round of guidance has moved the front’s arrival up a bit -- we now expect it to move through the WAFB viewing area during the latter half of Monday.

Monday’s front still does not look all that potent -- were going with only a 20% to 30% rain chance as it moves by, with most WAFB neighborhoods getting under one-quarter-inch of rain. The air behind Monday’s front will be cooler, but certainly not cold.

In the extended outlook, rain chances return for Thursday.

Wednesday, March 13, 2013

Beautiful Weather Continues!

By Jay Grymes & Steve Caparotta

** Did you see the International Space Station early this morning? **

** Look to the west about 40 minutes after sunset over the next few evenings to catch a glimpse of Comet Pan-STARRS!  Look below the moon this evening -- binoculars are suggested for the best view. **

Comet PANSTARRS and a waxing crescent moon over Baton Rouge Tuesday evening, courtesy of Alice Wack Stout. 

Enjoying this run of beautiful weather?  Who isn’t? And it keeps on coming!
Clear skies and subsiding winds, coupled with a second surge of cool and very dry Canadian air today will set the ‘Red Stick’ area up for another morning in the upper 30°s on Thursday – expect low to mid 30°s for many areas north and east of Baton Rouge by Thursday’s sunrise, with a handful of SW Mississippi communities possibly getting a light, brief freeze to start the day.  But blue skies and sunshine will allow temps to rebound quickly, and we expect to see the upper 60°s on Thursday afternoon for the metro area.
After that, here come warmer days, with highs in the 70°s for Friday and Saturday, and a few WAFB neighborhoods possibly getting up around 80° or more by Sunday and Monday.
A surface dome of high pressure has settled over the lower and middle Mississippi Valley today.  That dome will ease to the east and southeast over the next couple of days, setting us up with inflow from the Gulf by the latter half of the day Thursday and then continuing right through the coming weekend. 
The extended outlook still has a Canadian front stalling well to our north on Sunday, keeping the pressure gradient aligned to maintain a southerly flow.  A cool front out of the Southern Plains will then head towards the Gulf Coast on Monday, passing through the WAFB area late Monday into the pre-dawn hours of Tuesday.  At this point, we’re not expecting the Monday/Tuesday front to be much of a rainmaker - - those that do get rain will likely see less than one-half inch.
So here we are, headed into what should be a nice mid-March weekend - - with nearly perfect weather for Saturday’s St. Patrick’s Parade and celebration. 

Looking back, it’s been an interesting winter with generally mild temps and record and near-record rains.  After three very wet months, most of us have been noticeably drier over the past couple of weeks.  Yes, a few WAFB communities had rains of 2” or more earlier in the week, but that late Sunday/early Monday rain has been the only wet weather spell since Feb 25th. 

Yet the drier weather has also been accompanied by a shift to cooler-than-normal days.  The last three days of February, and 10 of the 13 days during March -- including today -- have been cooler-than-normal based on climatology.  In addition, after just 6 freezes through February and a seasonal low of 28° (on Dec 30th) for Baton Rouge’s Metro Airport, that same site has recorded three additional freezes during the first half of March 2013 including the winter’s only “hard” freeze, a 26° low on the morning of March 3rd (with temps at or below freezing for roughly 8 hours).

Although we expect another morning start in the 30°s tomorrow, that may well be the end of the 30°s for the winter season.  The extended outlook for the rest of March indicates that temps are likely to stay near-normal to above-normal.  Sure, we could still have a couple of chilly days (by March standards), but it appears as though we are finally done with the “freezes.”  However, the past couple of weeks serve as a reminder that winter does not officially end until the latter half of March.  2013’s spring equinox arrives at 6:02am on March 20th, a little more than an hour before sunrise.

Tuesday, March 12, 2013

More Sunshine -- Dry through the Weekend!
     --  12 March 3013 
After a chilly -- but not cold -- start to the day, we enjoyed another pretty afternoon across the WAFB viewing area although afternoon highs were generally 5° or more below the daily norm. Our forecast keeps the skies mainly clear through the next few days, with a notable warm-up coming by Friday and continuing into the weekend.
As we mentioned yesterday, we’ll get another “soft” surge of Canadian air during the next day or so, keeping temps below mid-March norms through Thursday. In fact, we expect another morning start in the upper 30°s for the ‘Red Stick’ on Thursday -- a reminder that we are still officially in winter!
A surface dome of high pressure will sit over the Mississippi Valley through Wednesday, then begin a slow drift to the east and southeast, settling over the Southeastern U.S. by Friday. We’ll see the winds swing around from northerly on Wednesday to something more southeasterly by Friday, adding to the warm-up as we head into the weekend.
We’ll be much warmer by Saturday -- morning lows at or above 50° and afternoon highs in the mid to upper 70°s -- with a little more moisture in the air thanks to the flow off the Gulf, allowing for a return of some fair-weather clouds.
A Canadian front will be working its way from north to south on Friday and Saturday. Yesterday we talked about this front sliding southward through the viewing area late Sunday into Monday, delivering a modest rain chance as it moved through. But today’s guidance indicates that the front will stall to our north, taking rain completely out of the weekend outlook. The latest NWS Weather Prediction Center forecast calls for a cool front to develop over the Plains on Monday and slip southeastward into the lower Mississippi Valley late Monday into early Tuesday. This boundary looks like it will be a relatively weak front, generating only limited amounts of rain as it slides by. We’ll keep tabs on it through the coming days.
Have you noticed the shift in local rain patterns recently? After a very wet December-through-February, the rains late Sunday/early Monday were the first in nearly two weeks, and it looks like we will stay dry through the next 5 or more days.
As an FYI -- the signals remain a bit mixed for the rest of March in terms of rainfall expectations, leaning slightly towards “normal to wet” for the last two weeks of the month. Don’t be storing the umbrella in the closet just yet!

Monday, March 11, 2013

Nice Week Ahead!

By Jay Grymes & Steve Caparotta

The rains and clouds moved out during the morning, but not before dumping as much as 1” to 2” and more for parts of the viewing area.  But the afternoon turned into a real beauty, although it remained noticeably cooler than the weekend temps. 

Yes, we say goodbye to the 70°s for a few days, but we’re also going to enjoy a sunny work week.

The clear skies and very dry Canadian air mass will mean a chilly start to your Tuesday, with sun-up temps slipping into the upper 30°s for metro Baton Rouge and down to the low to mid 30°s along and north of the LA/MS state line.  But sunshine on Tuesday should take afternoon temps back into the mid to upper 60°s, a little warmer than today.

A second, reinforcing surge of Canadian air on Wednesday will help keep temps on the “cool” side through the middle of the week -- even for early March.  Surface high pressure will settle over the middle and lower Mississippi Valley during the next couple of days, keeping us cool and dry, with hardly a cloud in the sky through Thursday.

As the surface high slowly slides east on Friday and Saturday, we’ll start to see a modest warm-up:  highs in the low 70°s by Friday and into the mid to upper 70°s for the weekend.  Skies should remain mainly sunny for Friday and Saturday, but by Saturday we’ll start to see steady SE to south winds bringing in a little Gulf moisture along with those warmer weekend temps.

A front to our north will slide towards the Bayou State through the weekend, enhancing those SE to south winds.  We expect partly cloudy skies for Sunday as the front gets closer, with a slight chance of rain late on Sunday.  But for the time being, our extended outlook into Sunday says the front will be late enough in the day to leave Sunday afternoon dry.

The front is expected to roll through the WAFB viewing area early Monday, bringing a 20% to 30% rain chance before clearing out later that day.  At this point, not only does Monday’s front show little potential for active weather, but it’s not even shaping up to be much of a rain-maker.

So enjoy the weather through the coming days!

Friday, March 8, 2013

Showers & T-Storms Late in the Weekend

By Jay Grymes & Steve Caparotta

** Don’t forget to ‘Spring Ahead’ on Sunday morning ... Daylight Saving Time officially returns at 2:00am this Sunday, and we move the clocks forward one hour.  That’s a good time to change the batteries in your smoke detectors and your NOAA Weather Radios. **

After a mainly sunny first half of the day, some high clouds have moved into the viewing area.  But it will still be a nice evening -- comfortably cool with temps in the 50°s.
Saturday looks like a pretty good day with highs in the 70°s -- but not exactly “picture perfect.”  Expect mostly cloudy skies for the better part of the day, and it will be breezy.  Sunday starts out dry under mostly cloudy skies, but expect scattered showers and a few t-storms by late Sunday afternoon into Sunday evening.  Rain chances increase into Sunday night and early Monday before clearing out later in the day.

Over the past couple of days we’ve been showing you the large upper-level trough and the storm system spinning over the eastern Pacific just off the California coast.  That system is now moving across the Desert Southwest and will be in the Southern Plains tomorrow.  The system’s surface low will continue to moving east-northeast, pulling a cold front through Texas.
The way things look right now, that cold front could be over the ArkLaTex by Sunday morning -- that’s a few hours sooner than what we’ve been thinking over the past two days -- which means the first of the pre-frontal rains will likely get here sooner on Sunday than we first thought.
We’re going with a 40% to 50% rain chance by the late afternoon and early evening on Sunday for most of the viewing area, especially WAFB communities north and west of the Capital City.  Those rain chances will rise for everyone into late Sunday night and early Monday morning as the cold front marches from west-to-east across the WAFB region.
The good news is that we still anticipate only 0.5” to 1.0” of rain for most of our neighborhoods, with isolated pockets possibly getting upwards of 1.5” or more.  More importantly, the “severe threat” with this front seems rather low.  Yes, there will be thunderstorms, and a few of them may become strong to severe, but currently this frontal passage does not look like it has the potential to generate a widespread severe weather outbreak.  (Of course, the WAFB Storm Team will be watching that for you throughout the weekend.)

The front is expected to continue to steadily move east and skies should beginning clearing by mid-day Monday, if not sooner.  We’ll get another dose of cooler air behind the front, but not anything “winter-like” -- highs on Monday and Tuesday will only reach the low to mid 60°s.  But the forecast through the upcoming work week looks like a dry one, with daytime highs back into the 70°s by mid-week.
Have a great weekend!

Thursday, March 7, 2013

Warming Trend into the Weekend

By Jay Grymes & Steve Caparotta

We expected another cold morning, but Metro Airport briefly slipped to 32°, a few degrees colder than expected.  Temps rebounded nicely through the morning and mid-day, but a deck of high clouds moved over the area during the afternoon, slowing the afternoon warm-up.  Satellite trends suggest that those clouds should exit to the east later this evening and overnight, allowing for mainly fair skies after midnight and into the morning on Friday.

Currently there is a large surface ridge of high pressure extending from the Great Lakes to the Gulf.  That elongated high will ease its way east over the next couple of days, allowing our winds to swing around to the east and southeast through the day on Friday.
Plan on a chilly start for Friday, with sunrise temps near 40° for much of the metro area.  Clouds will slowly increase through the day, with partly cloudy skies for the afternoon becoming mostly cloudy later in the day.  Friday will be warmer too, starting a 3-day run with highs in the 70°s.  Saturday will be the better “outdoor” day for the weekend, under a sun/cloud mix.
A storm system off the California coast today will starts its march eastward over the coming days.  It should be spinning over the U.S. “Four Corners” region tomorrow and head into the Southern Plains by early Saturday.  As we mentioned yesterday, the core of the storm will remain to our north with its attendant cold front extended southward.  That front is expected to be draped over eastern Texas by Sunday morning and is scheduled to sweep into southeast Louisiana by Monday morning.

The first of the pre-frontal rains will begin to show-up on Titan9 Doppler radar by Sunday afternoon, with rain chances rising through the remainder of Sunday as the front draws near.  For now, we’re posting a 30% rain chance for late Sunday afternoon, with those chances rising to 70% to 80% by late Sunday into early Monday morning.
The extended outlook from the NWS Weather Prediction Center (WPC) still indicates 0.5” to 1.0” of rain for the WAFB viewing area.  We do expect thunderstorms with the front’s approach and passage, but we still aren’t seeing this as a widespread severe weather event.
The front should move through fairly quickly, with clearing during the latter half of Monday.  The outlook for the rest of the work week looks “dry.”

We continue our review of severe weather threats during “Severe Weather Awareness Week.”  Lightning may well be the most under-rated weather threat of them all, and the threat is especially high for the Bayou State:
-- there have been roughly two dozen LA lightning deaths over the past 20 years, including a couple of fatalities in recent years right in the Baton Rouge area;
-- metro Baton Rouge averages 70-75 thunderstorm days per year, and while the threat is greatest in summer, thunderstorms occur year-round throughout the Gulf Coast region; and
-- at a frequency of nearly 20 cloud-to-ground flashes per square mile each year (based on analysis by the National Lightning Detection Network), Louisiana ranks #2 behind Florida in terms of lightning strikes . . . and southeast Louisiana is the most dangerous region within the state. (For our SW Mississippi viewers, Mississippi ranks #3).

The vast majority of Louisiana lightning fatalities and injuries occurred to those outdoors that failed to take action when the lightning threat developed.  And keep in mind, the greatest threat from lighting -- what catches many victims off-guard -- is that is does not have to be raining for lightning to strike. 

Here’s the simple rule: if you can see lightning or hear thunder, you are potentially in harm’s way.  And the best way to reduce the threat?  Just go indoors!

Wednesday, March 6, 2013

Another Cold Start on Thursday!

By Jay Grymes & Steve Caparotta

** Don’t forget that we ‘spring ahead’ this weekend ... Daylight Saving Time officially returns on Sunday morning at 2:00 AM **

We may be getting ready to move the clocks ahead one hour, but Nature is letting us know that it is still officially winter.  If this morning’s sunrise temps in the mid to upper 30°s didn’t send a clear reminder, then maybe tomorrow morning’s temps will: Thursday morning lows will likely be a couple of degrees lower than earlier this morning.  That means another round of freezes for WAFB viewers near and north of the LA/MS state line (although nothing nearly as cold as what they saw last Sunday morning).

Thursday afternoon, on the other hand should be a degree or two warmer than today, with another round of mainly clear skies and lots of sunshine.  Some neighborhoods north of Baton Rouge may slip back into the upper 30°s for Friday morning.  But the winds should swing around to the southeast by Friday afternoon, allowing temps to climb into the lower 70°s under fair to partly-cloudy skies.   And the warming trend continues into the weekend.

Highs for Saturday and Sunday should be in the mid 70°s, possibly even the upper 70°s by Sunday afternoon.  Saturday should be an enjoyable spring-like day under a mix of sun and clouds.  Sunday starts out mild and dry, but we’ll throw in a 20% to 30% rain chance by the afternoon and early evening.

Extended-range guidance is indicating that a storm currently evolving over the eastern Pacific will slide eastward across the Southwest U.S., reaching the Central and Southern Plains by Saturday morning.  As that storm system’s surface low tracks east-northeast across the center of the nation from Saturday into Monday, it will drag a trailing cold front through Texas and into Louisiana.

The NWS’s Weather Prediction Center (WPC) -- the recently “renamed” Hydrometeorological Prediction Center (HPC)  that we’ve referenced regularly in the past -- suggests that the cold front will be over east Texas by Sunday morning and over Louisiana’s southeastern parishes by sunrise on Monday.  Assuming that this timing is about right, that forecast would support pre-frontal showers and storms during the latter part of Sunday afternoon and early evening.  Rain chances would further increase from late Sunday evening into early Monday morning.  The WPC outlook also shows that the front will move steadily to the east, allowing for a clear-out during the latter half of Monday.

At this stage, it is a little too soon to offer concrete predictions regarding the severe-weather potential for Monday’s frontal passage.  The WPC is suggesting that Monday’s front could generate from 0.5” to maybe 1.0” of rain across our viewing area -- hinting that while we should be ready for thunderstorms, this may not be shaping up to be a widespread severe weather outbreak.   However, given the time of year and all that we’ve said this week (Severe Weather Awareness Week) about springtime severe threats, let’s keep our guard up until the picture gets clearer.

Projected rainfall from 6 PM Saturday through 7 PM Monday from NOAA's Weather Prediction Center.

While you are resetting your clocks, don’t forget to check the batteries in your NOAA Weather Radio..and your smoke detectors this weekend!

Tuesday, March 5, 2013

Cold Weather Returns Tonight!

By Jay Grymes & Steve Caparotta

** Severe Weather Awareness Week continues **

Thankfully, our weather this week will be rather benign, although get ready for a couple of very cold starts for Wednesday and Thursday!

Today’s cool front pushed on through as expected and skies cleared through the afternoon. A few neighborhoods reported light sprinkles with little if any accumulations for the area.

But behind today’s cold front comes another round of cold and dry Canadian air. That will mean a cold start for both Wednesday and Thursday, with morning lows in the mid to upper 30°s for many WAFB neighborhoods.

A steady warm-up kicks in by Friday, with highs back into the 70°s for the weekend. And our forecast stays dry into the weekend, with only a 20% chance of rain posted for the latter half of Sunday.

Our next cold front is scheduled for Monday, and for the time being it looks like that front moves through during the first half of the day. Based on what we see right now, Monday’s front will generate some rain, possibly even a few t-storms, but it is not shaping up to be a widespread severe-weather producer at this point. Of course, that could change in the coming days, so we’ll keep a watch on it for you.

Tying into Severe Weather Awareness Week, Jay researched and produced the graphics below relative to our tornado climatology in East Baton Rouge Parish.

- While tornadoes occur year-round, more than half of EBR’s past tornadoes occurred during the 4-month period of March-through-June ... and more than one-third occurred during the spring months (Mar-Apr-May).

- EBR Tornadoes have occurred during any time of day or night, with one-fourth occurring between 10pm-6am, the “sleeping hours” for most people.